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![Tianchen Ding](/assets/img/avatar_default.png)
reweight_eevdf() only keeps V unchanged inside itself. When se !=
cfs_rq->curr, it would be dequeued from rb tree first. So that V is
changed and the result is wrong. Pass the original V to reweight_eevdf()
to fix this issue.
Fixes: eab03c23c2
("sched/eevdf: Fix vruntime adjustment on reweight")
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
[peterz: flip if() condition for clarity]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Abel Wu <wuyun.abel@bytedance.com>
Link: https://lkml.kernel.org/r/20240306022133.81008-3-dtcccc@linux.alibaba.com
13222 lines
352 KiB
C
13222 lines
352 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
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*
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* Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* Interactivity improvements by Mike Galbraith
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* (C) 2007 Mike Galbraith <efault@gmx.de>
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*
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* Various enhancements by Dmitry Adamushko.
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* (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
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*
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* Group scheduling enhancements by Srivatsa Vaddagiri
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* Copyright IBM Corporation, 2007
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* Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
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*
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* Scaled math optimizations by Thomas Gleixner
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* Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
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*
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* Adaptive scheduling granularity, math enhancements by Peter Zijlstra
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
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*/
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#include <linux/energy_model.h>
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#include <linux/mmap_lock.h>
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#include <linux/hugetlb_inline.h>
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#include <linux/jiffies.h>
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#include <linux/mm_api.h>
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#include <linux/highmem.h>
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#include <linux/spinlock_api.h>
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#include <linux/cpumask_api.h>
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#include <linux/lockdep_api.h>
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#include <linux/softirq.h>
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#include <linux/refcount_api.h>
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#include <linux/topology.h>
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#include <linux/sched/clock.h>
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#include <linux/sched/cond_resched.h>
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#include <linux/sched/cputime.h>
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#include <linux/sched/isolation.h>
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#include <linux/sched/nohz.h>
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#include <linux/cpuidle.h>
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#include <linux/interrupt.h>
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#include <linux/memory-tiers.h>
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#include <linux/mempolicy.h>
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#include <linux/mutex_api.h>
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#include <linux/profile.h>
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#include <linux/psi.h>
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#include <linux/ratelimit.h>
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#include <linux/task_work.h>
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#include <linux/rbtree_augmented.h>
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#include <asm/switch_to.h>
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#include "sched.h"
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#include "stats.h"
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#include "autogroup.h"
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/*
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* The initial- and re-scaling of tunables is configurable
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*
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* Options are:
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*
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* SCHED_TUNABLESCALING_NONE - unscaled, always *1
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* SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
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* SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
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*
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* (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
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*/
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unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG;
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/*
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* Minimal preemption granularity for CPU-bound tasks:
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*
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* (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
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*/
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unsigned int sysctl_sched_base_slice = 750000ULL;
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static unsigned int normalized_sysctl_sched_base_slice = 750000ULL;
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const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
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int sched_thermal_decay_shift;
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static int __init setup_sched_thermal_decay_shift(char *str)
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{
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int _shift = 0;
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if (kstrtoint(str, 0, &_shift))
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pr_warn("Unable to set scheduler thermal pressure decay shift parameter\n");
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sched_thermal_decay_shift = clamp(_shift, 0, 10);
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return 1;
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}
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__setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
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#ifdef CONFIG_SMP
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/*
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* For asym packing, by default the lower numbered CPU has higher priority.
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*/
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int __weak arch_asym_cpu_priority(int cpu)
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{
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return -cpu;
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}
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/*
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* The margin used when comparing utilization with CPU capacity.
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*
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* (default: ~20%)
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*/
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#define fits_capacity(cap, max) ((cap) * 1280 < (max) * 1024)
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/*
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* The margin used when comparing CPU capacities.
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* is 'cap1' noticeably greater than 'cap2'
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*
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* (default: ~5%)
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*/
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#define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
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#endif
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#ifdef CONFIG_CFS_BANDWIDTH
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/*
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* Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
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* each time a cfs_rq requests quota.
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*
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* Note: in the case that the slice exceeds the runtime remaining (either due
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* to consumption or the quota being specified to be smaller than the slice)
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* we will always only issue the remaining available time.
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*
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* (default: 5 msec, units: microseconds)
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*/
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static unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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/* Restrict the NUMA promotion throughput (MB/s) for each target node. */
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static unsigned int sysctl_numa_balancing_promote_rate_limit = 65536;
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#endif
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#ifdef CONFIG_SYSCTL
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static struct ctl_table sched_fair_sysctls[] = {
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#ifdef CONFIG_CFS_BANDWIDTH
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{
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.procname = "sched_cfs_bandwidth_slice_us",
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.data = &sysctl_sched_cfs_bandwidth_slice,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = SYSCTL_ONE,
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},
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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{
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.procname = "numa_balancing_promote_rate_limit_MBps",
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.data = &sysctl_numa_balancing_promote_rate_limit,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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},
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#endif /* CONFIG_NUMA_BALANCING */
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{}
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};
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static int __init sched_fair_sysctl_init(void)
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{
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register_sysctl_init("kernel", sched_fair_sysctls);
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return 0;
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}
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late_initcall(sched_fair_sysctl_init);
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#endif
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static inline void update_load_add(struct load_weight *lw, unsigned long inc)
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{
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lw->weight += inc;
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lw->inv_weight = 0;
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}
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static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
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{
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lw->weight -= dec;
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lw->inv_weight = 0;
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}
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static inline void update_load_set(struct load_weight *lw, unsigned long w)
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{
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lw->weight = w;
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lw->inv_weight = 0;
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}
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/*
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* Increase the granularity value when there are more CPUs,
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* because with more CPUs the 'effective latency' as visible
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* to users decreases. But the relationship is not linear,
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* so pick a second-best guess by going with the log2 of the
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* number of CPUs.
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*
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* This idea comes from the SD scheduler of Con Kolivas:
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*/
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static unsigned int get_update_sysctl_factor(void)
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{
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unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8);
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unsigned int factor;
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switch (sysctl_sched_tunable_scaling) {
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case SCHED_TUNABLESCALING_NONE:
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factor = 1;
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break;
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case SCHED_TUNABLESCALING_LINEAR:
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factor = cpus;
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break;
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case SCHED_TUNABLESCALING_LOG:
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default:
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factor = 1 + ilog2(cpus);
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break;
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}
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return factor;
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}
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static void update_sysctl(void)
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{
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unsigned int factor = get_update_sysctl_factor();
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#define SET_SYSCTL(name) \
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(sysctl_##name = (factor) * normalized_sysctl_##name)
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SET_SYSCTL(sched_base_slice);
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#undef SET_SYSCTL
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}
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void __init sched_init_granularity(void)
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{
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update_sysctl();
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}
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#define WMULT_CONST (~0U)
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#define WMULT_SHIFT 32
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static void __update_inv_weight(struct load_weight *lw)
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{
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unsigned long w;
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if (likely(lw->inv_weight))
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return;
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w = scale_load_down(lw->weight);
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if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
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lw->inv_weight = 1;
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else if (unlikely(!w))
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lw->inv_weight = WMULT_CONST;
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else
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lw->inv_weight = WMULT_CONST / w;
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}
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/*
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* delta_exec * weight / lw.weight
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* OR
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* (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT
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*
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* Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case
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* we're guaranteed shift stays positive because inv_weight is guaranteed to
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* fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22.
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*
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* Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus
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* weight/lw.weight <= 1, and therefore our shift will also be positive.
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*/
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static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw)
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{
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u64 fact = scale_load_down(weight);
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u32 fact_hi = (u32)(fact >> 32);
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int shift = WMULT_SHIFT;
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int fs;
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__update_inv_weight(lw);
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if (unlikely(fact_hi)) {
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fs = fls(fact_hi);
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shift -= fs;
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fact >>= fs;
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}
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fact = mul_u32_u32(fact, lw->inv_weight);
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fact_hi = (u32)(fact >> 32);
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if (fact_hi) {
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fs = fls(fact_hi);
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shift -= fs;
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fact >>= fs;
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}
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return mul_u64_u32_shr(delta_exec, fact, shift);
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}
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/*
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* delta /= w
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*/
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static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se)
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{
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if (unlikely(se->load.weight != NICE_0_LOAD))
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delta = __calc_delta(delta, NICE_0_LOAD, &se->load);
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return delta;
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}
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const struct sched_class fair_sched_class;
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/**************************************************************
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* CFS operations on generic schedulable entities:
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*/
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#ifdef CONFIG_FAIR_GROUP_SCHED
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/* Walk up scheduling entities hierarchy */
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#define for_each_sched_entity(se) \
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for (; se; se = se->parent)
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static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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struct rq *rq = rq_of(cfs_rq);
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int cpu = cpu_of(rq);
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if (cfs_rq->on_list)
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return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list;
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cfs_rq->on_list = 1;
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/*
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* Ensure we either appear before our parent (if already
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* enqueued) or force our parent to appear after us when it is
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* enqueued. The fact that we always enqueue bottom-up
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* reduces this to two cases and a special case for the root
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* cfs_rq. Furthermore, it also means that we will always reset
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* tmp_alone_branch either when the branch is connected
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* to a tree or when we reach the top of the tree
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*/
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if (cfs_rq->tg->parent &&
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cfs_rq->tg->parent->cfs_rq[cpu]->on_list) {
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/*
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* If parent is already on the list, we add the child
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* just before. Thanks to circular linked property of
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* the list, this means to put the child at the tail
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* of the list that starts by parent.
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*/
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list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
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&(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list));
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/*
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* The branch is now connected to its tree so we can
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* reset tmp_alone_branch to the beginning of the
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* list.
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*/
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rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
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return true;
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}
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if (!cfs_rq->tg->parent) {
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/*
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* cfs rq without parent should be put
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* at the tail of the list.
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*/
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list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
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&rq->leaf_cfs_rq_list);
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/*
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* We have reach the top of a tree so we can reset
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* tmp_alone_branch to the beginning of the list.
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*/
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rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
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return true;
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}
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/*
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* The parent has not already been added so we want to
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* make sure that it will be put after us.
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* tmp_alone_branch points to the begin of the branch
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* where we will add parent.
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*/
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list_add_rcu(&cfs_rq->leaf_cfs_rq_list, rq->tmp_alone_branch);
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/*
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* update tmp_alone_branch to points to the new begin
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* of the branch
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*/
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rq->tmp_alone_branch = &cfs_rq->leaf_cfs_rq_list;
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return false;
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}
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static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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if (cfs_rq->on_list) {
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struct rq *rq = rq_of(cfs_rq);
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/*
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* With cfs_rq being unthrottled/throttled during an enqueue,
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* it can happen the tmp_alone_branch points the a leaf that
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* we finally want to del. In this case, tmp_alone_branch moves
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* to the prev element but it will point to rq->leaf_cfs_rq_list
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* at the end of the enqueue.
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*/
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if (rq->tmp_alone_branch == &cfs_rq->leaf_cfs_rq_list)
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rq->tmp_alone_branch = cfs_rq->leaf_cfs_rq_list.prev;
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list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
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cfs_rq->on_list = 0;
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}
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}
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static inline void assert_list_leaf_cfs_rq(struct rq *rq)
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{
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SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list);
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}
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/* Iterate thr' all leaf cfs_rq's on a runqueue */
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#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \
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list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list, \
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leaf_cfs_rq_list)
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/* Do the two (enqueued) entities belong to the same group ? */
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static inline struct cfs_rq *
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is_same_group(struct sched_entity *se, struct sched_entity *pse)
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{
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if (se->cfs_rq == pse->cfs_rq)
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return se->cfs_rq;
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return NULL;
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}
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static inline struct sched_entity *parent_entity(const struct sched_entity *se)
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{
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return se->parent;
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}
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static void
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find_matching_se(struct sched_entity **se, struct sched_entity **pse)
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{
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int se_depth, pse_depth;
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/*
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* preemption test can be made between sibling entities who are in the
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* same cfs_rq i.e who have a common parent. Walk up the hierarchy of
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* both tasks until we find their ancestors who are siblings of common
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* parent.
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*/
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/* First walk up until both entities are at same depth */
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se_depth = (*se)->depth;
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pse_depth = (*pse)->depth;
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while (se_depth > pse_depth) {
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se_depth--;
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*se = parent_entity(*se);
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}
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while (pse_depth > se_depth) {
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pse_depth--;
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*pse = parent_entity(*pse);
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}
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while (!is_same_group(*se, *pse)) {
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*se = parent_entity(*se);
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*pse = parent_entity(*pse);
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}
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}
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static int tg_is_idle(struct task_group *tg)
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{
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return tg->idle > 0;
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}
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static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->idle > 0;
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}
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static int se_is_idle(struct sched_entity *se)
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{
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if (entity_is_task(se))
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return task_has_idle_policy(task_of(se));
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return cfs_rq_is_idle(group_cfs_rq(se));
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}
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#else /* !CONFIG_FAIR_GROUP_SCHED */
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#define for_each_sched_entity(se) \
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for (; se; se = NULL)
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static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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return true;
|
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}
|
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|
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static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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}
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static inline void assert_list_leaf_cfs_rq(struct rq *rq)
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{
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}
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|
|
#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \
|
|
for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos)
|
|
|
|
static inline struct sched_entity *parent_entity(struct sched_entity *se)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static inline void
|
|
find_matching_se(struct sched_entity **se, struct sched_entity **pse)
|
|
{
|
|
}
|
|
|
|
static inline int tg_is_idle(struct task_group *tg)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static int se_is_idle(struct sched_entity *se)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
static __always_inline
|
|
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec);
|
|
|
|
/**************************************************************
|
|
* Scheduling class tree data structure manipulation methods:
|
|
*/
|
|
|
|
static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
|
|
{
|
|
s64 delta = (s64)(vruntime - max_vruntime);
|
|
if (delta > 0)
|
|
max_vruntime = vruntime;
|
|
|
|
return max_vruntime;
|
|
}
|
|
|
|
static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
|
|
{
|
|
s64 delta = (s64)(vruntime - min_vruntime);
|
|
if (delta < 0)
|
|
min_vruntime = vruntime;
|
|
|
|
return min_vruntime;
|
|
}
|
|
|
|
static inline bool entity_before(const struct sched_entity *a,
|
|
const struct sched_entity *b)
|
|
{
|
|
/*
|
|
* Tiebreak on vruntime seems unnecessary since it can
|
|
* hardly happen.
|
|
*/
|
|
return (s64)(a->deadline - b->deadline) < 0;
|
|
}
|
|
|
|
static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
return (s64)(se->vruntime - cfs_rq->min_vruntime);
|
|
}
|
|
|
|
#define __node_2_se(node) \
|
|
rb_entry((node), struct sched_entity, run_node)
|
|
|
|
/*
|
|
* Compute virtual time from the per-task service numbers:
|
|
*
|
|
* Fair schedulers conserve lag:
|
|
*
|
|
* \Sum lag_i = 0
|
|
*
|
|
* Where lag_i is given by:
|
|
*
|
|
* lag_i = S - s_i = w_i * (V - v_i)
|
|
*
|
|
* Where S is the ideal service time and V is it's virtual time counterpart.
|
|
* Therefore:
|
|
*
|
|
* \Sum lag_i = 0
|
|
* \Sum w_i * (V - v_i) = 0
|
|
* \Sum w_i * V - w_i * v_i = 0
|
|
*
|
|
* From which we can solve an expression for V in v_i (which we have in
|
|
* se->vruntime):
|
|
*
|
|
* \Sum v_i * w_i \Sum v_i * w_i
|
|
* V = -------------- = --------------
|
|
* \Sum w_i W
|
|
*
|
|
* Specifically, this is the weighted average of all entity virtual runtimes.
|
|
*
|
|
* [[ NOTE: this is only equal to the ideal scheduler under the condition
|
|
* that join/leave operations happen at lag_i = 0, otherwise the
|
|
* virtual time has non-continguous motion equivalent to:
|
|
*
|
|
* V +-= lag_i / W
|
|
*
|
|
* Also see the comment in place_entity() that deals with this. ]]
|
|
*
|
|
* However, since v_i is u64, and the multiplcation could easily overflow
|
|
* transform it into a relative form that uses smaller quantities:
|
|
*
|
|
* Substitute: v_i == (v_i - v0) + v0
|
|
*
|
|
* \Sum ((v_i - v0) + v0) * w_i \Sum (v_i - v0) * w_i
|
|
* V = ---------------------------- = --------------------- + v0
|
|
* W W
|
|
*
|
|
* Which we track using:
|
|
*
|
|
* v0 := cfs_rq->min_vruntime
|
|
* \Sum (v_i - v0) * w_i := cfs_rq->avg_vruntime
|
|
* \Sum w_i := cfs_rq->avg_load
|
|
*
|
|
* Since min_vruntime is a monotonic increasing variable that closely tracks
|
|
* the per-task service, these deltas: (v_i - v), will be in the order of the
|
|
* maximal (virtual) lag induced in the system due to quantisation.
|
|
*
|
|
* Also, we use scale_load_down() to reduce the size.
|
|
*
|
|
* As measured, the max (key * weight) value was ~44 bits for a kernel build.
|
|
*/
|
|
static void
|
|
avg_vruntime_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
unsigned long weight = scale_load_down(se->load.weight);
|
|
s64 key = entity_key(cfs_rq, se);
|
|
|
|
cfs_rq->avg_vruntime += key * weight;
|
|
cfs_rq->avg_load += weight;
|
|
}
|
|
|
|
static void
|
|
avg_vruntime_sub(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
unsigned long weight = scale_load_down(se->load.weight);
|
|
s64 key = entity_key(cfs_rq, se);
|
|
|
|
cfs_rq->avg_vruntime -= key * weight;
|
|
cfs_rq->avg_load -= weight;
|
|
}
|
|
|
|
static inline
|
|
void avg_vruntime_update(struct cfs_rq *cfs_rq, s64 delta)
|
|
{
|
|
/*
|
|
* v' = v + d ==> avg_vruntime' = avg_runtime - d*avg_load
|
|
*/
|
|
cfs_rq->avg_vruntime -= cfs_rq->avg_load * delta;
|
|
}
|
|
|
|
/*
|
|
* Specifically: avg_runtime() + 0 must result in entity_eligible() := true
|
|
* For this to be so, the result of this function must have a left bias.
|
|
*/
|
|
u64 avg_vruntime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
s64 avg = cfs_rq->avg_vruntime;
|
|
long load = cfs_rq->avg_load;
|
|
|
|
if (curr && curr->on_rq) {
|
|
unsigned long weight = scale_load_down(curr->load.weight);
|
|
|
|
avg += entity_key(cfs_rq, curr) * weight;
|
|
load += weight;
|
|
}
|
|
|
|
if (load) {
|
|
/* sign flips effective floor / ceil */
|
|
if (avg < 0)
|
|
avg -= (load - 1);
|
|
avg = div_s64(avg, load);
|
|
}
|
|
|
|
return cfs_rq->min_vruntime + avg;
|
|
}
|
|
|
|
/*
|
|
* lag_i = S - s_i = w_i * (V - v_i)
|
|
*
|
|
* However, since V is approximated by the weighted average of all entities it
|
|
* is possible -- by addition/removal/reweight to the tree -- to move V around
|
|
* and end up with a larger lag than we started with.
|
|
*
|
|
* Limit this to either double the slice length with a minimum of TICK_NSEC
|
|
* since that is the timing granularity.
|
|
*
|
|
* EEVDF gives the following limit for a steady state system:
|
|
*
|
|
* -r_max < lag < max(r_max, q)
|
|
*
|
|
* XXX could add max_slice to the augmented data to track this.
|
|
*/
|
|
static void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
s64 lag, limit;
|
|
|
|
SCHED_WARN_ON(!se->on_rq);
|
|
lag = avg_vruntime(cfs_rq) - se->vruntime;
|
|
|
|
limit = calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se);
|
|
se->vlag = clamp(lag, -limit, limit);
|
|
}
|
|
|
|
/*
|
|
* Entity is eligible once it received less service than it ought to have,
|
|
* eg. lag >= 0.
|
|
*
|
|
* lag_i = S - s_i = w_i*(V - v_i)
|
|
*
|
|
* lag_i >= 0 -> V >= v_i
|
|
*
|
|
* \Sum (v_i - v)*w_i
|
|
* V = ------------------ + v
|
|
* \Sum w_i
|
|
*
|
|
* lag_i >= 0 -> \Sum (v_i - v)*w_i >= (v_i - v)*(\Sum w_i)
|
|
*
|
|
* Note: using 'avg_vruntime() > se->vruntime' is inacurate due
|
|
* to the loss in precision caused by the division.
|
|
*/
|
|
static int vruntime_eligible(struct cfs_rq *cfs_rq, u64 vruntime)
|
|
{
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
s64 avg = cfs_rq->avg_vruntime;
|
|
long load = cfs_rq->avg_load;
|
|
|
|
if (curr && curr->on_rq) {
|
|
unsigned long weight = scale_load_down(curr->load.weight);
|
|
|
|
avg += entity_key(cfs_rq, curr) * weight;
|
|
load += weight;
|
|
}
|
|
|
|
return avg >= (s64)(vruntime - cfs_rq->min_vruntime) * load;
|
|
}
|
|
|
|
int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
return vruntime_eligible(cfs_rq, se->vruntime);
|
|
}
|
|
|
|
static u64 __update_min_vruntime(struct cfs_rq *cfs_rq, u64 vruntime)
|
|
{
|
|
u64 min_vruntime = cfs_rq->min_vruntime;
|
|
/*
|
|
* open coded max_vruntime() to allow updating avg_vruntime
|
|
*/
|
|
s64 delta = (s64)(vruntime - min_vruntime);
|
|
if (delta > 0) {
|
|
avg_vruntime_update(cfs_rq, delta);
|
|
min_vruntime = vruntime;
|
|
}
|
|
return min_vruntime;
|
|
}
|
|
|
|
static void update_min_vruntime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *se = __pick_root_entity(cfs_rq);
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
u64 vruntime = cfs_rq->min_vruntime;
|
|
|
|
if (curr) {
|
|
if (curr->on_rq)
|
|
vruntime = curr->vruntime;
|
|
else
|
|
curr = NULL;
|
|
}
|
|
|
|
if (se) {
|
|
if (!curr)
|
|
vruntime = se->min_vruntime;
|
|
else
|
|
vruntime = min_vruntime(vruntime, se->min_vruntime);
|
|
}
|
|
|
|
/* ensure we never gain time by being placed backwards. */
|
|
u64_u32_store(cfs_rq->min_vruntime,
|
|
__update_min_vruntime(cfs_rq, vruntime));
|
|
}
|
|
|
|
static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
|
|
{
|
|
return entity_before(__node_2_se(a), __node_2_se(b));
|
|
}
|
|
|
|
#define vruntime_gt(field, lse, rse) ({ (s64)((lse)->field - (rse)->field) > 0; })
|
|
|
|
static inline void __min_vruntime_update(struct sched_entity *se, struct rb_node *node)
|
|
{
|
|
if (node) {
|
|
struct sched_entity *rse = __node_2_se(node);
|
|
if (vruntime_gt(min_vruntime, se, rse))
|
|
se->min_vruntime = rse->min_vruntime;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* se->min_vruntime = min(se->vruntime, {left,right}->min_vruntime)
|
|
*/
|
|
static inline bool min_vruntime_update(struct sched_entity *se, bool exit)
|
|
{
|
|
u64 old_min_vruntime = se->min_vruntime;
|
|
struct rb_node *node = &se->run_node;
|
|
|
|
se->min_vruntime = se->vruntime;
|
|
__min_vruntime_update(se, node->rb_right);
|
|
__min_vruntime_update(se, node->rb_left);
|
|
|
|
return se->min_vruntime == old_min_vruntime;
|
|
}
|
|
|
|
RB_DECLARE_CALLBACKS(static, min_vruntime_cb, struct sched_entity,
|
|
run_node, min_vruntime, min_vruntime_update);
|
|
|
|
/*
|
|
* Enqueue an entity into the rb-tree:
|
|
*/
|
|
static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
avg_vruntime_add(cfs_rq, se);
|
|
se->min_vruntime = se->vruntime;
|
|
rb_add_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline,
|
|
__entity_less, &min_vruntime_cb);
|
|
}
|
|
|
|
static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
rb_erase_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline,
|
|
&min_vruntime_cb);
|
|
avg_vruntime_sub(cfs_rq, se);
|
|
}
|
|
|
|
struct sched_entity *__pick_root_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *root = cfs_rq->tasks_timeline.rb_root.rb_node;
|
|
|
|
if (!root)
|
|
return NULL;
|
|
|
|
return __node_2_se(root);
|
|
}
|
|
|
|
struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *left = rb_first_cached(&cfs_rq->tasks_timeline);
|
|
|
|
if (!left)
|
|
return NULL;
|
|
|
|
return __node_2_se(left);
|
|
}
|
|
|
|
/*
|
|
* Earliest Eligible Virtual Deadline First
|
|
*
|
|
* In order to provide latency guarantees for different request sizes
|
|
* EEVDF selects the best runnable task from two criteria:
|
|
*
|
|
* 1) the task must be eligible (must be owed service)
|
|
*
|
|
* 2) from those tasks that meet 1), we select the one
|
|
* with the earliest virtual deadline.
|
|
*
|
|
* We can do this in O(log n) time due to an augmented RB-tree. The
|
|
* tree keeps the entries sorted on deadline, but also functions as a
|
|
* heap based on the vruntime by keeping:
|
|
*
|
|
* se->min_vruntime = min(se->vruntime, se->{left,right}->min_vruntime)
|
|
*
|
|
* Which allows tree pruning through eligibility.
|
|
*/
|
|
static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *node = cfs_rq->tasks_timeline.rb_root.rb_node;
|
|
struct sched_entity *se = __pick_first_entity(cfs_rq);
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
struct sched_entity *best = NULL;
|
|
|
|
/*
|
|
* We can safely skip eligibility check if there is only one entity
|
|
* in this cfs_rq, saving some cycles.
|
|
*/
|
|
if (cfs_rq->nr_running == 1)
|
|
return curr && curr->on_rq ? curr : se;
|
|
|
|
if (curr && (!curr->on_rq || !entity_eligible(cfs_rq, curr)))
|
|
curr = NULL;
|
|
|
|
/*
|
|
* Once selected, run a task until it either becomes non-eligible or
|
|
* until it gets a new slice. See the HACK in set_next_entity().
|
|
*/
|
|
if (sched_feat(RUN_TO_PARITY) && curr && curr->vlag == curr->deadline)
|
|
return curr;
|
|
|
|
/* Pick the leftmost entity if it's eligible */
|
|
if (se && entity_eligible(cfs_rq, se)) {
|
|
best = se;
|
|
goto found;
|
|
}
|
|
|
|
/* Heap search for the EEVD entity */
|
|
while (node) {
|
|
struct rb_node *left = node->rb_left;
|
|
|
|
/*
|
|
* Eligible entities in left subtree are always better
|
|
* choices, since they have earlier deadlines.
|
|
*/
|
|
if (left && vruntime_eligible(cfs_rq,
|
|
__node_2_se(left)->min_vruntime)) {
|
|
node = left;
|
|
continue;
|
|
}
|
|
|
|
se = __node_2_se(node);
|
|
|
|
/*
|
|
* The left subtree either is empty or has no eligible
|
|
* entity, so check the current node since it is the one
|
|
* with earliest deadline that might be eligible.
|
|
*/
|
|
if (entity_eligible(cfs_rq, se)) {
|
|
best = se;
|
|
break;
|
|
}
|
|
|
|
node = node->rb_right;
|
|
}
|
|
found:
|
|
if (!best || (curr && entity_before(curr, best)))
|
|
best = curr;
|
|
|
|
return best;
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *last = rb_last(&cfs_rq->tasks_timeline.rb_root);
|
|
|
|
if (!last)
|
|
return NULL;
|
|
|
|
return __node_2_se(last);
|
|
}
|
|
|
|
/**************************************************************
|
|
* Scheduling class statistics methods:
|
|
*/
|
|
#ifdef CONFIG_SMP
|
|
int sched_update_scaling(void)
|
|
{
|
|
unsigned int factor = get_update_sysctl_factor();
|
|
|
|
#define WRT_SYSCTL(name) \
|
|
(normalized_sysctl_##name = sysctl_##name / (factor))
|
|
WRT_SYSCTL(sched_base_slice);
|
|
#undef WRT_SYSCTL
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se);
|
|
|
|
/*
|
|
* XXX: strictly: vd_i += N*r_i/w_i such that: vd_i > ve_i
|
|
* this is probably good enough.
|
|
*/
|
|
static void update_deadline(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
if ((s64)(se->vruntime - se->deadline) < 0)
|
|
return;
|
|
|
|
/*
|
|
* For EEVDF the virtual time slope is determined by w_i (iow.
|
|
* nice) while the request time r_i is determined by
|
|
* sysctl_sched_base_slice.
|
|
*/
|
|
se->slice = sysctl_sched_base_slice;
|
|
|
|
/*
|
|
* EEVDF: vd_i = ve_i + r_i / w_i
|
|
*/
|
|
se->deadline = se->vruntime + calc_delta_fair(se->slice, se);
|
|
|
|
/*
|
|
* The task has consumed its request, reschedule.
|
|
*/
|
|
if (cfs_rq->nr_running > 1) {
|
|
resched_curr(rq_of(cfs_rq));
|
|
clear_buddies(cfs_rq, se);
|
|
}
|
|
}
|
|
|
|
#include "pelt.h"
|
|
#ifdef CONFIG_SMP
|
|
|
|
static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
|
|
static unsigned long task_h_load(struct task_struct *p);
|
|
static unsigned long capacity_of(int cpu);
|
|
|
|
/* Give new sched_entity start runnable values to heavy its load in infant time */
|
|
void init_entity_runnable_average(struct sched_entity *se)
|
|
{
|
|
struct sched_avg *sa = &se->avg;
|
|
|
|
memset(sa, 0, sizeof(*sa));
|
|
|
|
/*
|
|
* Tasks are initialized with full load to be seen as heavy tasks until
|
|
* they get a chance to stabilize to their real load level.
|
|
* Group entities are initialized with zero load to reflect the fact that
|
|
* nothing has been attached to the task group yet.
|
|
*/
|
|
if (entity_is_task(se))
|
|
sa->load_avg = scale_load_down(se->load.weight);
|
|
|
|
/* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
|
|
}
|
|
|
|
/*
|
|
* With new tasks being created, their initial util_avgs are extrapolated
|
|
* based on the cfs_rq's current util_avg:
|
|
*
|
|
* util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight
|
|
*
|
|
* However, in many cases, the above util_avg does not give a desired
|
|
* value. Moreover, the sum of the util_avgs may be divergent, such
|
|
* as when the series is a harmonic series.
|
|
*
|
|
* To solve this problem, we also cap the util_avg of successive tasks to
|
|
* only 1/2 of the left utilization budget:
|
|
*
|
|
* util_avg_cap = (cpu_scale - cfs_rq->avg.util_avg) / 2^n
|
|
*
|
|
* where n denotes the nth task and cpu_scale the CPU capacity.
|
|
*
|
|
* For example, for a CPU with 1024 of capacity, a simplest series from
|
|
* the beginning would be like:
|
|
*
|
|
* task util_avg: 512, 256, 128, 64, 32, 16, 8, ...
|
|
* cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ...
|
|
*
|
|
* Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap)
|
|
* if util_avg > util_avg_cap.
|
|
*/
|
|
void post_init_entity_util_avg(struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
struct sched_avg *sa = &se->avg;
|
|
long cpu_scale = arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq)));
|
|
long cap = (long)(cpu_scale - cfs_rq->avg.util_avg) / 2;
|
|
|
|
if (p->sched_class != &fair_sched_class) {
|
|
/*
|
|
* For !fair tasks do:
|
|
*
|
|
update_cfs_rq_load_avg(now, cfs_rq);
|
|
attach_entity_load_avg(cfs_rq, se);
|
|
switched_from_fair(rq, p);
|
|
*
|
|
* such that the next switched_to_fair() has the
|
|
* expected state.
|
|
*/
|
|
se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
|
|
return;
|
|
}
|
|
|
|
if (cap > 0) {
|
|
if (cfs_rq->avg.util_avg != 0) {
|
|
sa->util_avg = cfs_rq->avg.util_avg * se->load.weight;
|
|
sa->util_avg /= (cfs_rq->avg.load_avg + 1);
|
|
|
|
if (sa->util_avg > cap)
|
|
sa->util_avg = cap;
|
|
} else {
|
|
sa->util_avg = cap;
|
|
}
|
|
}
|
|
|
|
sa->runnable_avg = sa->util_avg;
|
|
}
|
|
|
|
#else /* !CONFIG_SMP */
|
|
void init_entity_runnable_average(struct sched_entity *se)
|
|
{
|
|
}
|
|
void post_init_entity_util_avg(struct task_struct *p)
|
|
{
|
|
}
|
|
static void update_tg_load_avg(struct cfs_rq *cfs_rq)
|
|
{
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static s64 update_curr_se(struct rq *rq, struct sched_entity *curr)
|
|
{
|
|
u64 now = rq_clock_task(rq);
|
|
s64 delta_exec;
|
|
|
|
delta_exec = now - curr->exec_start;
|
|
if (unlikely(delta_exec <= 0))
|
|
return delta_exec;
|
|
|
|
curr->exec_start = now;
|
|
curr->sum_exec_runtime += delta_exec;
|
|
|
|
if (schedstat_enabled()) {
|
|
struct sched_statistics *stats;
|
|
|
|
stats = __schedstats_from_se(curr);
|
|
__schedstat_set(stats->exec_max,
|
|
max(delta_exec, stats->exec_max));
|
|
}
|
|
|
|
return delta_exec;
|
|
}
|
|
|
|
static inline void update_curr_task(struct task_struct *p, s64 delta_exec)
|
|
{
|
|
trace_sched_stat_runtime(p, delta_exec);
|
|
account_group_exec_runtime(p, delta_exec);
|
|
cgroup_account_cputime(p, delta_exec);
|
|
if (p->dl_server)
|
|
dl_server_update(p->dl_server, delta_exec);
|
|
}
|
|
|
|
/*
|
|
* Used by other classes to account runtime.
|
|
*/
|
|
s64 update_curr_common(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
s64 delta_exec;
|
|
|
|
delta_exec = update_curr_se(rq, &curr->se);
|
|
if (likely(delta_exec > 0))
|
|
update_curr_task(curr, delta_exec);
|
|
|
|
return delta_exec;
|
|
}
|
|
|
|
/*
|
|
* Update the current task's runtime statistics.
|
|
*/
|
|
static void update_curr(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
s64 delta_exec;
|
|
|
|
if (unlikely(!curr))
|
|
return;
|
|
|
|
delta_exec = update_curr_se(rq_of(cfs_rq), curr);
|
|
if (unlikely(delta_exec <= 0))
|
|
return;
|
|
|
|
curr->vruntime += calc_delta_fair(delta_exec, curr);
|
|
update_deadline(cfs_rq, curr);
|
|
update_min_vruntime(cfs_rq);
|
|
|
|
if (entity_is_task(curr))
|
|
update_curr_task(task_of(curr), delta_exec);
|
|
|
|
account_cfs_rq_runtime(cfs_rq, delta_exec);
|
|
}
|
|
|
|
static void update_curr_fair(struct rq *rq)
|
|
{
|
|
update_curr(cfs_rq_of(&rq->curr->se));
|
|
}
|
|
|
|
static inline void
|
|
update_stats_wait_start_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
struct sched_statistics *stats;
|
|
struct task_struct *p = NULL;
|
|
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
stats = __schedstats_from_se(se);
|
|
|
|
if (entity_is_task(se))
|
|
p = task_of(se);
|
|
|
|
__update_stats_wait_start(rq_of(cfs_rq), p, stats);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_wait_end_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
struct sched_statistics *stats;
|
|
struct task_struct *p = NULL;
|
|
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
stats = __schedstats_from_se(se);
|
|
|
|
/*
|
|
* When the sched_schedstat changes from 0 to 1, some sched se
|
|
* maybe already in the runqueue, the se->statistics.wait_start
|
|
* will be 0.So it will let the delta wrong. We need to avoid this
|
|
* scenario.
|
|
*/
|
|
if (unlikely(!schedstat_val(stats->wait_start)))
|
|
return;
|
|
|
|
if (entity_is_task(se))
|
|
p = task_of(se);
|
|
|
|
__update_stats_wait_end(rq_of(cfs_rq), p, stats);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_enqueue_sleeper_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
struct sched_statistics *stats;
|
|
struct task_struct *tsk = NULL;
|
|
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
stats = __schedstats_from_se(se);
|
|
|
|
if (entity_is_task(se))
|
|
tsk = task_of(se);
|
|
|
|
__update_stats_enqueue_sleeper(rq_of(cfs_rq), tsk, stats);
|
|
}
|
|
|
|
/*
|
|
* Task is being enqueued - update stats:
|
|
*/
|
|
static inline void
|
|
update_stats_enqueue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
/*
|
|
* Are we enqueueing a waiting task? (for current tasks
|
|
* a dequeue/enqueue event is a NOP)
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
update_stats_wait_start_fair(cfs_rq, se);
|
|
|
|
if (flags & ENQUEUE_WAKEUP)
|
|
update_stats_enqueue_sleeper_fair(cfs_rq, se);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_dequeue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
/*
|
|
* Mark the end of the wait period if dequeueing a
|
|
* waiting task:
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
update_stats_wait_end_fair(cfs_rq, se);
|
|
|
|
if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) {
|
|
struct task_struct *tsk = task_of(se);
|
|
unsigned int state;
|
|
|
|
/* XXX racy against TTWU */
|
|
state = READ_ONCE(tsk->__state);
|
|
if (state & TASK_INTERRUPTIBLE)
|
|
__schedstat_set(tsk->stats.sleep_start,
|
|
rq_clock(rq_of(cfs_rq)));
|
|
if (state & TASK_UNINTERRUPTIBLE)
|
|
__schedstat_set(tsk->stats.block_start,
|
|
rq_clock(rq_of(cfs_rq)));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We are picking a new current task - update its stats:
|
|
*/
|
|
static inline void
|
|
update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* We are starting a new run period:
|
|
*/
|
|
se->exec_start = rq_clock_task(rq_of(cfs_rq));
|
|
}
|
|
|
|
/**************************************************
|
|
* Scheduling class queueing methods:
|
|
*/
|
|
|
|
static inline bool is_core_idle(int cpu)
|
|
{
|
|
#ifdef CONFIG_SCHED_SMT
|
|
int sibling;
|
|
|
|
for_each_cpu(sibling, cpu_smt_mask(cpu)) {
|
|
if (cpu == sibling)
|
|
continue;
|
|
|
|
if (!idle_cpu(sibling))
|
|
return false;
|
|
}
|
|
#endif
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
#define NUMA_IMBALANCE_MIN 2
|
|
|
|
static inline long
|
|
adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
|
|
{
|
|
/*
|
|
* Allow a NUMA imbalance if busy CPUs is less than the maximum
|
|
* threshold. Above this threshold, individual tasks may be contending
|
|
* for both memory bandwidth and any shared HT resources. This is an
|
|
* approximation as the number of running tasks may not be related to
|
|
* the number of busy CPUs due to sched_setaffinity.
|
|
*/
|
|
if (dst_running > imb_numa_nr)
|
|
return imbalance;
|
|
|
|
/*
|
|
* Allow a small imbalance based on a simple pair of communicating
|
|
* tasks that remain local when the destination is lightly loaded.
|
|
*/
|
|
if (imbalance <= NUMA_IMBALANCE_MIN)
|
|
return 0;
|
|
|
|
return imbalance;
|
|
}
|
|
#endif /* CONFIG_NUMA */
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/*
|
|
* Approximate time to scan a full NUMA task in ms. The task scan period is
|
|
* calculated based on the tasks virtual memory size and
|
|
* numa_balancing_scan_size.
|
|
*/
|
|
unsigned int sysctl_numa_balancing_scan_period_min = 1000;
|
|
unsigned int sysctl_numa_balancing_scan_period_max = 60000;
|
|
|
|
/* Portion of address space to scan in MB */
|
|
unsigned int sysctl_numa_balancing_scan_size = 256;
|
|
|
|
/* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
|
|
unsigned int sysctl_numa_balancing_scan_delay = 1000;
|
|
|
|
/* The page with hint page fault latency < threshold in ms is considered hot */
|
|
unsigned int sysctl_numa_balancing_hot_threshold = MSEC_PER_SEC;
|
|
|
|
struct numa_group {
|
|
refcount_t refcount;
|
|
|
|
spinlock_t lock; /* nr_tasks, tasks */
|
|
int nr_tasks;
|
|
pid_t gid;
|
|
int active_nodes;
|
|
|
|
struct rcu_head rcu;
|
|
unsigned long total_faults;
|
|
unsigned long max_faults_cpu;
|
|
/*
|
|
* faults[] array is split into two regions: faults_mem and faults_cpu.
|
|
*
|
|
* Faults_cpu is used to decide whether memory should move
|
|
* towards the CPU. As a consequence, these stats are weighted
|
|
* more by CPU use than by memory faults.
|
|
*/
|
|
unsigned long faults[];
|
|
};
|
|
|
|
/*
|
|
* For functions that can be called in multiple contexts that permit reading
|
|
* ->numa_group (see struct task_struct for locking rules).
|
|
*/
|
|
static struct numa_group *deref_task_numa_group(struct task_struct *p)
|
|
{
|
|
return rcu_dereference_check(p->numa_group, p == current ||
|
|
(lockdep_is_held(__rq_lockp(task_rq(p))) && !READ_ONCE(p->on_cpu)));
|
|
}
|
|
|
|
static struct numa_group *deref_curr_numa_group(struct task_struct *p)
|
|
{
|
|
return rcu_dereference_protected(p->numa_group, p == current);
|
|
}
|
|
|
|
static inline unsigned long group_faults_priv(struct numa_group *ng);
|
|
static inline unsigned long group_faults_shared(struct numa_group *ng);
|
|
|
|
static unsigned int task_nr_scan_windows(struct task_struct *p)
|
|
{
|
|
unsigned long rss = 0;
|
|
unsigned long nr_scan_pages;
|
|
|
|
/*
|
|
* Calculations based on RSS as non-present and empty pages are skipped
|
|
* by the PTE scanner and NUMA hinting faults should be trapped based
|
|
* on resident pages
|
|
*/
|
|
nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT);
|
|
rss = get_mm_rss(p->mm);
|
|
if (!rss)
|
|
rss = nr_scan_pages;
|
|
|
|
rss = round_up(rss, nr_scan_pages);
|
|
return rss / nr_scan_pages;
|
|
}
|
|
|
|
/* For sanity's sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */
|
|
#define MAX_SCAN_WINDOW 2560
|
|
|
|
static unsigned int task_scan_min(struct task_struct *p)
|
|
{
|
|
unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size);
|
|
unsigned int scan, floor;
|
|
unsigned int windows = 1;
|
|
|
|
if (scan_size < MAX_SCAN_WINDOW)
|
|
windows = MAX_SCAN_WINDOW / scan_size;
|
|
floor = 1000 / windows;
|
|
|
|
scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p);
|
|
return max_t(unsigned int, floor, scan);
|
|
}
|
|
|
|
static unsigned int task_scan_start(struct task_struct *p)
|
|
{
|
|
unsigned long smin = task_scan_min(p);
|
|
unsigned long period = smin;
|
|
struct numa_group *ng;
|
|
|
|
/* Scale the maximum scan period with the amount of shared memory. */
|
|
rcu_read_lock();
|
|
ng = rcu_dereference(p->numa_group);
|
|
if (ng) {
|
|
unsigned long shared = group_faults_shared(ng);
|
|
unsigned long private = group_faults_priv(ng);
|
|
|
|
period *= refcount_read(&ng->refcount);
|
|
period *= shared + 1;
|
|
period /= private + shared + 1;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return max(smin, period);
|
|
}
|
|
|
|
static unsigned int task_scan_max(struct task_struct *p)
|
|
{
|
|
unsigned long smin = task_scan_min(p);
|
|
unsigned long smax;
|
|
struct numa_group *ng;
|
|
|
|
/* Watch for min being lower than max due to floor calculations */
|
|
smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
|
|
|
|
/* Scale the maximum scan period with the amount of shared memory. */
|
|
ng = deref_curr_numa_group(p);
|
|
if (ng) {
|
|
unsigned long shared = group_faults_shared(ng);
|
|
unsigned long private = group_faults_priv(ng);
|
|
unsigned long period = smax;
|
|
|
|
period *= refcount_read(&ng->refcount);
|
|
period *= shared + 1;
|
|
period /= private + shared + 1;
|
|
|
|
smax = max(smax, period);
|
|
}
|
|
|
|
return max(smin, smax);
|
|
}
|
|
|
|
static void account_numa_enqueue(struct rq *rq, struct task_struct *p)
|
|
{
|
|
rq->nr_numa_running += (p->numa_preferred_nid != NUMA_NO_NODE);
|
|
rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p));
|
|
}
|
|
|
|
static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
|
|
{
|
|
rq->nr_numa_running -= (p->numa_preferred_nid != NUMA_NO_NODE);
|
|
rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p));
|
|
}
|
|
|
|
/* Shared or private faults. */
|
|
#define NR_NUMA_HINT_FAULT_TYPES 2
|
|
|
|
/* Memory and CPU locality */
|
|
#define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
|
|
|
|
/* Averaged statistics, and temporary buffers. */
|
|
#define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2)
|
|
|
|
pid_t task_numa_group_id(struct task_struct *p)
|
|
{
|
|
struct numa_group *ng;
|
|
pid_t gid = 0;
|
|
|
|
rcu_read_lock();
|
|
ng = rcu_dereference(p->numa_group);
|
|
if (ng)
|
|
gid = ng->gid;
|
|
rcu_read_unlock();
|
|
|
|
return gid;
|
|
}
|
|
|
|
/*
|
|
* The averaged statistics, shared & private, memory & CPU,
|
|
* occupy the first half of the array. The second half of the
|
|
* array is for current counters, which are averaged into the
|
|
* first set by task_numa_placement.
|
|
*/
|
|
static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv)
|
|
{
|
|
return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv;
|
|
}
|
|
|
|
static inline unsigned long task_faults(struct task_struct *p, int nid)
|
|
{
|
|
if (!p->numa_faults)
|
|
return 0;
|
|
|
|
return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] +
|
|
p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)];
|
|
}
|
|
|
|
static inline unsigned long group_faults(struct task_struct *p, int nid)
|
|
{
|
|
struct numa_group *ng = deref_task_numa_group(p);
|
|
|
|
if (!ng)
|
|
return 0;
|
|
|
|
return ng->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
|
|
ng->faults[task_faults_idx(NUMA_MEM, nid, 1)];
|
|
}
|
|
|
|
static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
|
|
{
|
|
return group->faults[task_faults_idx(NUMA_CPU, nid, 0)] +
|
|
group->faults[task_faults_idx(NUMA_CPU, nid, 1)];
|
|
}
|
|
|
|
static inline unsigned long group_faults_priv(struct numa_group *ng)
|
|
{
|
|
unsigned long faults = 0;
|
|
int node;
|
|
|
|
for_each_online_node(node) {
|
|
faults += ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
|
|
}
|
|
|
|
return faults;
|
|
}
|
|
|
|
static inline unsigned long group_faults_shared(struct numa_group *ng)
|
|
{
|
|
unsigned long faults = 0;
|
|
int node;
|
|
|
|
for_each_online_node(node) {
|
|
faults += ng->faults[task_faults_idx(NUMA_MEM, node, 0)];
|
|
}
|
|
|
|
return faults;
|
|
}
|
|
|
|
/*
|
|
* A node triggering more than 1/3 as many NUMA faults as the maximum is
|
|
* considered part of a numa group's pseudo-interleaving set. Migrations
|
|
* between these nodes are slowed down, to allow things to settle down.
|
|
*/
|
|
#define ACTIVE_NODE_FRACTION 3
|
|
|
|
static bool numa_is_active_node(int nid, struct numa_group *ng)
|
|
{
|
|
return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu;
|
|
}
|
|
|
|
/* Handle placement on systems where not all nodes are directly connected. */
|
|
static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
|
|
int lim_dist, bool task)
|
|
{
|
|
unsigned long score = 0;
|
|
int node, max_dist;
|
|
|
|
/*
|
|
* All nodes are directly connected, and the same distance
|
|
* from each other. No need for fancy placement algorithms.
|
|
*/
|
|
if (sched_numa_topology_type == NUMA_DIRECT)
|
|
return 0;
|
|
|
|
/* sched_max_numa_distance may be changed in parallel. */
|
|
max_dist = READ_ONCE(sched_max_numa_distance);
|
|
/*
|
|
* This code is called for each node, introducing N^2 complexity,
|
|
* which should be ok given the number of nodes rarely exceeds 8.
|
|
*/
|
|
for_each_online_node(node) {
|
|
unsigned long faults;
|
|
int dist = node_distance(nid, node);
|
|
|
|
/*
|
|
* The furthest away nodes in the system are not interesting
|
|
* for placement; nid was already counted.
|
|
*/
|
|
if (dist >= max_dist || node == nid)
|
|
continue;
|
|
|
|
/*
|
|
* On systems with a backplane NUMA topology, compare groups
|
|
* of nodes, and move tasks towards the group with the most
|
|
* memory accesses. When comparing two nodes at distance
|
|
* "hoplimit", only nodes closer by than "hoplimit" are part
|
|
* of each group. Skip other nodes.
|
|
*/
|
|
if (sched_numa_topology_type == NUMA_BACKPLANE && dist >= lim_dist)
|
|
continue;
|
|
|
|
/* Add up the faults from nearby nodes. */
|
|
if (task)
|
|
faults = task_faults(p, node);
|
|
else
|
|
faults = group_faults(p, node);
|
|
|
|
/*
|
|
* On systems with a glueless mesh NUMA topology, there are
|
|
* no fixed "groups of nodes". Instead, nodes that are not
|
|
* directly connected bounce traffic through intermediate
|
|
* nodes; a numa_group can occupy any set of nodes.
|
|
* The further away a node is, the less the faults count.
|
|
* This seems to result in good task placement.
|
|
*/
|
|
if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
|
|
faults *= (max_dist - dist);
|
|
faults /= (max_dist - LOCAL_DISTANCE);
|
|
}
|
|
|
|
score += faults;
|
|
}
|
|
|
|
return score;
|
|
}
|
|
|
|
/*
|
|
* These return the fraction of accesses done by a particular task, or
|
|
* task group, on a particular numa node. The group weight is given a
|
|
* larger multiplier, in order to group tasks together that are almost
|
|
* evenly spread out between numa nodes.
|
|
*/
|
|
static inline unsigned long task_weight(struct task_struct *p, int nid,
|
|
int dist)
|
|
{
|
|
unsigned long faults, total_faults;
|
|
|
|
if (!p->numa_faults)
|
|
return 0;
|
|
|
|
total_faults = p->total_numa_faults;
|
|
|
|
if (!total_faults)
|
|
return 0;
|
|
|
|
faults = task_faults(p, nid);
|
|
faults += score_nearby_nodes(p, nid, dist, true);
|
|
|
|
return 1000 * faults / total_faults;
|
|
}
|
|
|
|
static inline unsigned long group_weight(struct task_struct *p, int nid,
|
|
int dist)
|
|
{
|
|
struct numa_group *ng = deref_task_numa_group(p);
|
|
unsigned long faults, total_faults;
|
|
|
|
if (!ng)
|
|
return 0;
|
|
|
|
total_faults = ng->total_faults;
|
|
|
|
if (!total_faults)
|
|
return 0;
|
|
|
|
faults = group_faults(p, nid);
|
|
faults += score_nearby_nodes(p, nid, dist, false);
|
|
|
|
return 1000 * faults / total_faults;
|
|
}
|
|
|
|
/*
|
|
* If memory tiering mode is enabled, cpupid of slow memory page is
|
|
* used to record scan time instead of CPU and PID. When tiering mode
|
|
* is disabled at run time, the scan time (in cpupid) will be
|
|
* interpreted as CPU and PID. So CPU needs to be checked to avoid to
|
|
* access out of array bound.
|
|
*/
|
|
static inline bool cpupid_valid(int cpupid)
|
|
{
|
|
return cpupid_to_cpu(cpupid) < nr_cpu_ids;
|
|
}
|
|
|
|
/*
|
|
* For memory tiering mode, if there are enough free pages (more than
|
|
* enough watermark defined here) in fast memory node, to take full
|
|
* advantage of fast memory capacity, all recently accessed slow
|
|
* memory pages will be migrated to fast memory node without
|
|
* considering hot threshold.
|
|
*/
|
|
static bool pgdat_free_space_enough(struct pglist_data *pgdat)
|
|
{
|
|
int z;
|
|
unsigned long enough_wmark;
|
|
|
|
enough_wmark = max(1UL * 1024 * 1024 * 1024 >> PAGE_SHIFT,
|
|
pgdat->node_present_pages >> 4);
|
|
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
|
|
struct zone *zone = pgdat->node_zones + z;
|
|
|
|
if (!populated_zone(zone))
|
|
continue;
|
|
|
|
if (zone_watermark_ok(zone, 0,
|
|
wmark_pages(zone, WMARK_PROMO) + enough_wmark,
|
|
ZONE_MOVABLE, 0))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* For memory tiering mode, when page tables are scanned, the scan
|
|
* time will be recorded in struct page in addition to make page
|
|
* PROT_NONE for slow memory page. So when the page is accessed, in
|
|
* hint page fault handler, the hint page fault latency is calculated
|
|
* via,
|
|
*
|
|
* hint page fault latency = hint page fault time - scan time
|
|
*
|
|
* The smaller the hint page fault latency, the higher the possibility
|
|
* for the page to be hot.
|
|
*/
|
|
static int numa_hint_fault_latency(struct folio *folio)
|
|
{
|
|
int last_time, time;
|
|
|
|
time = jiffies_to_msecs(jiffies);
|
|
last_time = folio_xchg_access_time(folio, time);
|
|
|
|
return (time - last_time) & PAGE_ACCESS_TIME_MASK;
|
|
}
|
|
|
|
/*
|
|
* For memory tiering mode, too high promotion/demotion throughput may
|
|
* hurt application latency. So we provide a mechanism to rate limit
|
|
* the number of pages that are tried to be promoted.
|
|
*/
|
|
static bool numa_promotion_rate_limit(struct pglist_data *pgdat,
|
|
unsigned long rate_limit, int nr)
|
|
{
|
|
unsigned long nr_cand;
|
|
unsigned int now, start;
|
|
|
|
now = jiffies_to_msecs(jiffies);
|
|
mod_node_page_state(pgdat, PGPROMOTE_CANDIDATE, nr);
|
|
nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
|
|
start = pgdat->nbp_rl_start;
|
|
if (now - start > MSEC_PER_SEC &&
|
|
cmpxchg(&pgdat->nbp_rl_start, start, now) == start)
|
|
pgdat->nbp_rl_nr_cand = nr_cand;
|
|
if (nr_cand - pgdat->nbp_rl_nr_cand >= rate_limit)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
#define NUMA_MIGRATION_ADJUST_STEPS 16
|
|
|
|
static void numa_promotion_adjust_threshold(struct pglist_data *pgdat,
|
|
unsigned long rate_limit,
|
|
unsigned int ref_th)
|
|
{
|
|
unsigned int now, start, th_period, unit_th, th;
|
|
unsigned long nr_cand, ref_cand, diff_cand;
|
|
|
|
now = jiffies_to_msecs(jiffies);
|
|
th_period = sysctl_numa_balancing_scan_period_max;
|
|
start = pgdat->nbp_th_start;
|
|
if (now - start > th_period &&
|
|
cmpxchg(&pgdat->nbp_th_start, start, now) == start) {
|
|
ref_cand = rate_limit *
|
|
sysctl_numa_balancing_scan_period_max / MSEC_PER_SEC;
|
|
nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
|
|
diff_cand = nr_cand - pgdat->nbp_th_nr_cand;
|
|
unit_th = ref_th * 2 / NUMA_MIGRATION_ADJUST_STEPS;
|
|
th = pgdat->nbp_threshold ? : ref_th;
|
|
if (diff_cand > ref_cand * 11 / 10)
|
|
th = max(th - unit_th, unit_th);
|
|
else if (diff_cand < ref_cand * 9 / 10)
|
|
th = min(th + unit_th, ref_th * 2);
|
|
pgdat->nbp_th_nr_cand = nr_cand;
|
|
pgdat->nbp_threshold = th;
|
|
}
|
|
}
|
|
|
|
bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
|
|
int src_nid, int dst_cpu)
|
|
{
|
|
struct numa_group *ng = deref_curr_numa_group(p);
|
|
int dst_nid = cpu_to_node(dst_cpu);
|
|
int last_cpupid, this_cpupid;
|
|
|
|
/*
|
|
* Cannot migrate to memoryless nodes.
|
|
*/
|
|
if (!node_state(dst_nid, N_MEMORY))
|
|
return false;
|
|
|
|
/*
|
|
* The pages in slow memory node should be migrated according
|
|
* to hot/cold instead of private/shared.
|
|
*/
|
|
if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
|
|
!node_is_toptier(src_nid)) {
|
|
struct pglist_data *pgdat;
|
|
unsigned long rate_limit;
|
|
unsigned int latency, th, def_th;
|
|
|
|
pgdat = NODE_DATA(dst_nid);
|
|
if (pgdat_free_space_enough(pgdat)) {
|
|
/* workload changed, reset hot threshold */
|
|
pgdat->nbp_threshold = 0;
|
|
return true;
|
|
}
|
|
|
|
def_th = sysctl_numa_balancing_hot_threshold;
|
|
rate_limit = sysctl_numa_balancing_promote_rate_limit << \
|
|
(20 - PAGE_SHIFT);
|
|
numa_promotion_adjust_threshold(pgdat, rate_limit, def_th);
|
|
|
|
th = pgdat->nbp_threshold ? : def_th;
|
|
latency = numa_hint_fault_latency(folio);
|
|
if (latency >= th)
|
|
return false;
|
|
|
|
return !numa_promotion_rate_limit(pgdat, rate_limit,
|
|
folio_nr_pages(folio));
|
|
}
|
|
|
|
this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
|
|
last_cpupid = folio_xchg_last_cpupid(folio, this_cpupid);
|
|
|
|
if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
|
|
!node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
|
|
return false;
|
|
|
|
/*
|
|
* Allow first faults or private faults to migrate immediately early in
|
|
* the lifetime of a task. The magic number 4 is based on waiting for
|
|
* two full passes of the "multi-stage node selection" test that is
|
|
* executed below.
|
|
*/
|
|
if ((p->numa_preferred_nid == NUMA_NO_NODE || p->numa_scan_seq <= 4) &&
|
|
(cpupid_pid_unset(last_cpupid) || cpupid_match_pid(p, last_cpupid)))
|
|
return true;
|
|
|
|
/*
|
|
* Multi-stage node selection is used in conjunction with a periodic
|
|
* migration fault to build a temporal task<->page relation. By using
|
|
* a two-stage filter we remove short/unlikely relations.
|
|
*
|
|
* Using P(p) ~ n_p / n_t as per frequentist probability, we can equate
|
|
* a task's usage of a particular page (n_p) per total usage of this
|
|
* page (n_t) (in a given time-span) to a probability.
|
|
*
|
|
* Our periodic faults will sample this probability and getting the
|
|
* same result twice in a row, given these samples are fully
|
|
* independent, is then given by P(n)^2, provided our sample period
|
|
* is sufficiently short compared to the usage pattern.
|
|
*
|
|
* This quadric squishes small probabilities, making it less likely we
|
|
* act on an unlikely task<->page relation.
|
|
*/
|
|
if (!cpupid_pid_unset(last_cpupid) &&
|
|
cpupid_to_nid(last_cpupid) != dst_nid)
|
|
return false;
|
|
|
|
/* Always allow migrate on private faults */
|
|
if (cpupid_match_pid(p, last_cpupid))
|
|
return true;
|
|
|
|
/* A shared fault, but p->numa_group has not been set up yet. */
|
|
if (!ng)
|
|
return true;
|
|
|
|
/*
|
|
* Destination node is much more heavily used than the source
|
|
* node? Allow migration.
|
|
*/
|
|
if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) *
|
|
ACTIVE_NODE_FRACTION)
|
|
return true;
|
|
|
|
/*
|
|
* Distribute memory according to CPU & memory use on each node,
|
|
* with 3/4 hysteresis to avoid unnecessary memory migrations:
|
|
*
|
|
* faults_cpu(dst) 3 faults_cpu(src)
|
|
* --------------- * - > ---------------
|
|
* faults_mem(dst) 4 faults_mem(src)
|
|
*/
|
|
return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 >
|
|
group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4;
|
|
}
|
|
|
|
/*
|
|
* 'numa_type' describes the node at the moment of load balancing.
|
|
*/
|
|
enum numa_type {
|
|
/* The node has spare capacity that can be used to run more tasks. */
|
|
node_has_spare = 0,
|
|
/*
|
|
* The node is fully used and the tasks don't compete for more CPU
|
|
* cycles. Nevertheless, some tasks might wait before running.
|
|
*/
|
|
node_fully_busy,
|
|
/*
|
|
* The node is overloaded and can't provide expected CPU cycles to all
|
|
* tasks.
|
|
*/
|
|
node_overloaded
|
|
};
|
|
|
|
/* Cached statistics for all CPUs within a node */
|
|
struct numa_stats {
|
|
unsigned long load;
|
|
unsigned long runnable;
|
|
unsigned long util;
|
|
/* Total compute capacity of CPUs on a node */
|
|
unsigned long compute_capacity;
|
|
unsigned int nr_running;
|
|
unsigned int weight;
|
|
enum numa_type node_type;
|
|
int idle_cpu;
|
|
};
|
|
|
|
struct task_numa_env {
|
|
struct task_struct *p;
|
|
|
|
int src_cpu, src_nid;
|
|
int dst_cpu, dst_nid;
|
|
int imb_numa_nr;
|
|
|
|
struct numa_stats src_stats, dst_stats;
|
|
|
|
int imbalance_pct;
|
|
int dist;
|
|
|
|
struct task_struct *best_task;
|
|
long best_imp;
|
|
int best_cpu;
|
|
};
|
|
|
|
static unsigned long cpu_load(struct rq *rq);
|
|
static unsigned long cpu_runnable(struct rq *rq);
|
|
|
|
static inline enum
|
|
numa_type numa_classify(unsigned int imbalance_pct,
|
|
struct numa_stats *ns)
|
|
{
|
|
if ((ns->nr_running > ns->weight) &&
|
|
(((ns->compute_capacity * 100) < (ns->util * imbalance_pct)) ||
|
|
((ns->compute_capacity * imbalance_pct) < (ns->runnable * 100))))
|
|
return node_overloaded;
|
|
|
|
if ((ns->nr_running < ns->weight) ||
|
|
(((ns->compute_capacity * 100) > (ns->util * imbalance_pct)) &&
|
|
((ns->compute_capacity * imbalance_pct) > (ns->runnable * 100))))
|
|
return node_has_spare;
|
|
|
|
return node_fully_busy;
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
/* Forward declarations of select_idle_sibling helpers */
|
|
static inline bool test_idle_cores(int cpu);
|
|
static inline int numa_idle_core(int idle_core, int cpu)
|
|
{
|
|
if (!static_branch_likely(&sched_smt_present) ||
|
|
idle_core >= 0 || !test_idle_cores(cpu))
|
|
return idle_core;
|
|
|
|
/*
|
|
* Prefer cores instead of packing HT siblings
|
|
* and triggering future load balancing.
|
|
*/
|
|
if (is_core_idle(cpu))
|
|
idle_core = cpu;
|
|
|
|
return idle_core;
|
|
}
|
|
#else
|
|
static inline int numa_idle_core(int idle_core, int cpu)
|
|
{
|
|
return idle_core;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Gather all necessary information to make NUMA balancing placement
|
|
* decisions that are compatible with standard load balancer. This
|
|
* borrows code and logic from update_sg_lb_stats but sharing a
|
|
* common implementation is impractical.
|
|
*/
|
|
static void update_numa_stats(struct task_numa_env *env,
|
|
struct numa_stats *ns, int nid,
|
|
bool find_idle)
|
|
{
|
|
int cpu, idle_core = -1;
|
|
|
|
memset(ns, 0, sizeof(*ns));
|
|
ns->idle_cpu = -1;
|
|
|
|
rcu_read_lock();
|
|
for_each_cpu(cpu, cpumask_of_node(nid)) {
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
ns->load += cpu_load(rq);
|
|
ns->runnable += cpu_runnable(rq);
|
|
ns->util += cpu_util_cfs(cpu);
|
|
ns->nr_running += rq->cfs.h_nr_running;
|
|
ns->compute_capacity += capacity_of(cpu);
|
|
|
|
if (find_idle && idle_core < 0 && !rq->nr_running && idle_cpu(cpu)) {
|
|
if (READ_ONCE(rq->numa_migrate_on) ||
|
|
!cpumask_test_cpu(cpu, env->p->cpus_ptr))
|
|
continue;
|
|
|
|
if (ns->idle_cpu == -1)
|
|
ns->idle_cpu = cpu;
|
|
|
|
idle_core = numa_idle_core(idle_core, cpu);
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
ns->weight = cpumask_weight(cpumask_of_node(nid));
|
|
|
|
ns->node_type = numa_classify(env->imbalance_pct, ns);
|
|
|
|
if (idle_core >= 0)
|
|
ns->idle_cpu = idle_core;
|
|
}
|
|
|
|
static void task_numa_assign(struct task_numa_env *env,
|
|
struct task_struct *p, long imp)
|
|
{
|
|
struct rq *rq = cpu_rq(env->dst_cpu);
|
|
|
|
/* Check if run-queue part of active NUMA balance. */
|
|
if (env->best_cpu != env->dst_cpu && xchg(&rq->numa_migrate_on, 1)) {
|
|
int cpu;
|
|
int start = env->dst_cpu;
|
|
|
|
/* Find alternative idle CPU. */
|
|
for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start + 1) {
|
|
if (cpu == env->best_cpu || !idle_cpu(cpu) ||
|
|
!cpumask_test_cpu(cpu, env->p->cpus_ptr)) {
|
|
continue;
|
|
}
|
|
|
|
env->dst_cpu = cpu;
|
|
rq = cpu_rq(env->dst_cpu);
|
|
if (!xchg(&rq->numa_migrate_on, 1))
|
|
goto assign;
|
|
}
|
|
|
|
/* Failed to find an alternative idle CPU */
|
|
return;
|
|
}
|
|
|
|
assign:
|
|
/*
|
|
* Clear previous best_cpu/rq numa-migrate flag, since task now
|
|
* found a better CPU to move/swap.
|
|
*/
|
|
if (env->best_cpu != -1 && env->best_cpu != env->dst_cpu) {
|
|
rq = cpu_rq(env->best_cpu);
|
|
WRITE_ONCE(rq->numa_migrate_on, 0);
|
|
}
|
|
|
|
if (env->best_task)
|
|
put_task_struct(env->best_task);
|
|
if (p)
|
|
get_task_struct(p);
|
|
|
|
env->best_task = p;
|
|
env->best_imp = imp;
|
|
env->best_cpu = env->dst_cpu;
|
|
}
|
|
|
|
static bool load_too_imbalanced(long src_load, long dst_load,
|
|
struct task_numa_env *env)
|
|
{
|
|
long imb, old_imb;
|
|
long orig_src_load, orig_dst_load;
|
|
long src_capacity, dst_capacity;
|
|
|
|
/*
|
|
* The load is corrected for the CPU capacity available on each node.
|
|
*
|
|
* src_load dst_load
|
|
* ------------ vs ---------
|
|
* src_capacity dst_capacity
|
|
*/
|
|
src_capacity = env->src_stats.compute_capacity;
|
|
dst_capacity = env->dst_stats.compute_capacity;
|
|
|
|
imb = abs(dst_load * src_capacity - src_load * dst_capacity);
|
|
|
|
orig_src_load = env->src_stats.load;
|
|
orig_dst_load = env->dst_stats.load;
|
|
|
|
old_imb = abs(orig_dst_load * src_capacity - orig_src_load * dst_capacity);
|
|
|
|
/* Would this change make things worse? */
|
|
return (imb > old_imb);
|
|
}
|
|
|
|
/*
|
|
* Maximum NUMA importance can be 1998 (2*999);
|
|
* SMALLIMP @ 30 would be close to 1998/64.
|
|
* Used to deter task migration.
|
|
*/
|
|
#define SMALLIMP 30
|
|
|
|
/*
|
|
* This checks if the overall compute and NUMA accesses of the system would
|
|
* be improved if the source tasks was migrated to the target dst_cpu taking
|
|
* into account that it might be best if task running on the dst_cpu should
|
|
* be exchanged with the source task
|
|
*/
|
|
static bool task_numa_compare(struct task_numa_env *env,
|
|
long taskimp, long groupimp, bool maymove)
|
|
{
|
|
struct numa_group *cur_ng, *p_ng = deref_curr_numa_group(env->p);
|
|
struct rq *dst_rq = cpu_rq(env->dst_cpu);
|
|
long imp = p_ng ? groupimp : taskimp;
|
|
struct task_struct *cur;
|
|
long src_load, dst_load;
|
|
int dist = env->dist;
|
|
long moveimp = imp;
|
|
long load;
|
|
bool stopsearch = false;
|
|
|
|
if (READ_ONCE(dst_rq->numa_migrate_on))
|
|
return false;
|
|
|
|
rcu_read_lock();
|
|
cur = rcu_dereference(dst_rq->curr);
|
|
if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur)))
|
|
cur = NULL;
|
|
|
|
/*
|
|
* Because we have preemption enabled we can get migrated around and
|
|
* end try selecting ourselves (current == env->p) as a swap candidate.
|
|
*/
|
|
if (cur == env->p) {
|
|
stopsearch = true;
|
|
goto unlock;
|
|
}
|
|
|
|
if (!cur) {
|
|
if (maymove && moveimp >= env->best_imp)
|
|
goto assign;
|
|
else
|
|
goto unlock;
|
|
}
|
|
|
|
/* Skip this swap candidate if cannot move to the source cpu. */
|
|
if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr))
|
|
goto unlock;
|
|
|
|
/*
|
|
* Skip this swap candidate if it is not moving to its preferred
|
|
* node and the best task is.
|
|
*/
|
|
if (env->best_task &&
|
|
env->best_task->numa_preferred_nid == env->src_nid &&
|
|
cur->numa_preferred_nid != env->src_nid) {
|
|
goto unlock;
|
|
}
|
|
|
|
/*
|
|
* "imp" is the fault differential for the source task between the
|
|
* source and destination node. Calculate the total differential for
|
|
* the source task and potential destination task. The more negative
|
|
* the value is, the more remote accesses that would be expected to
|
|
* be incurred if the tasks were swapped.
|
|
*
|
|
* If dst and source tasks are in the same NUMA group, or not
|
|
* in any group then look only at task weights.
|
|
*/
|
|
cur_ng = rcu_dereference(cur->numa_group);
|
|
if (cur_ng == p_ng) {
|
|
/*
|
|
* Do not swap within a group or between tasks that have
|
|
* no group if there is spare capacity. Swapping does
|
|
* not address the load imbalance and helps one task at
|
|
* the cost of punishing another.
|
|
*/
|
|
if (env->dst_stats.node_type == node_has_spare)
|
|
goto unlock;
|
|
|
|
imp = taskimp + task_weight(cur, env->src_nid, dist) -
|
|
task_weight(cur, env->dst_nid, dist);
|
|
/*
|
|
* Add some hysteresis to prevent swapping the
|
|
* tasks within a group over tiny differences.
|
|
*/
|
|
if (cur_ng)
|
|
imp -= imp / 16;
|
|
} else {
|
|
/*
|
|
* Compare the group weights. If a task is all by itself
|
|
* (not part of a group), use the task weight instead.
|
|
*/
|
|
if (cur_ng && p_ng)
|
|
imp += group_weight(cur, env->src_nid, dist) -
|
|
group_weight(cur, env->dst_nid, dist);
|
|
else
|
|
imp += task_weight(cur, env->src_nid, dist) -
|
|
task_weight(cur, env->dst_nid, dist);
|
|
}
|
|
|
|
/* Discourage picking a task already on its preferred node */
|
|
if (cur->numa_preferred_nid == env->dst_nid)
|
|
imp -= imp / 16;
|
|
|
|
/*
|
|
* Encourage picking a task that moves to its preferred node.
|
|
* This potentially makes imp larger than it's maximum of
|
|
* 1998 (see SMALLIMP and task_weight for why) but in this
|
|
* case, it does not matter.
|
|
*/
|
|
if (cur->numa_preferred_nid == env->src_nid)
|
|
imp += imp / 8;
|
|
|
|
if (maymove && moveimp > imp && moveimp > env->best_imp) {
|
|
imp = moveimp;
|
|
cur = NULL;
|
|
goto assign;
|
|
}
|
|
|
|
/*
|
|
* Prefer swapping with a task moving to its preferred node over a
|
|
* task that is not.
|
|
*/
|
|
if (env->best_task && cur->numa_preferred_nid == env->src_nid &&
|
|
env->best_task->numa_preferred_nid != env->src_nid) {
|
|
goto assign;
|
|
}
|
|
|
|
/*
|
|
* If the NUMA importance is less than SMALLIMP,
|
|
* task migration might only result in ping pong
|
|
* of tasks and also hurt performance due to cache
|
|
* misses.
|
|
*/
|
|
if (imp < SMALLIMP || imp <= env->best_imp + SMALLIMP / 2)
|
|
goto unlock;
|
|
|
|
/*
|
|
* In the overloaded case, try and keep the load balanced.
|
|
*/
|
|
load = task_h_load(env->p) - task_h_load(cur);
|
|
if (!load)
|
|
goto assign;
|
|
|
|
dst_load = env->dst_stats.load + load;
|
|
src_load = env->src_stats.load - load;
|
|
|
|
if (load_too_imbalanced(src_load, dst_load, env))
|
|
goto unlock;
|
|
|
|
assign:
|
|
/* Evaluate an idle CPU for a task numa move. */
|
|
if (!cur) {
|
|
int cpu = env->dst_stats.idle_cpu;
|
|
|
|
/* Nothing cached so current CPU went idle since the search. */
|
|
if (cpu < 0)
|
|
cpu = env->dst_cpu;
|
|
|
|
/*
|
|
* If the CPU is no longer truly idle and the previous best CPU
|
|
* is, keep using it.
|
|
*/
|
|
if (!idle_cpu(cpu) && env->best_cpu >= 0 &&
|
|
idle_cpu(env->best_cpu)) {
|
|
cpu = env->best_cpu;
|
|
}
|
|
|
|
env->dst_cpu = cpu;
|
|
}
|
|
|
|
task_numa_assign(env, cur, imp);
|
|
|
|
/*
|
|
* If a move to idle is allowed because there is capacity or load
|
|
* balance improves then stop the search. While a better swap
|
|
* candidate may exist, a search is not free.
|
|
*/
|
|
if (maymove && !cur && env->best_cpu >= 0 && idle_cpu(env->best_cpu))
|
|
stopsearch = true;
|
|
|
|
/*
|
|
* If a swap candidate must be identified and the current best task
|
|
* moves its preferred node then stop the search.
|
|
*/
|
|
if (!maymove && env->best_task &&
|
|
env->best_task->numa_preferred_nid == env->src_nid) {
|
|
stopsearch = true;
|
|
}
|
|
unlock:
|
|
rcu_read_unlock();
|
|
|
|
return stopsearch;
|
|
}
|
|
|
|
static void task_numa_find_cpu(struct task_numa_env *env,
|
|
long taskimp, long groupimp)
|
|
{
|
|
bool maymove = false;
|
|
int cpu;
|
|
|
|
/*
|
|
* If dst node has spare capacity, then check if there is an
|
|
* imbalance that would be overruled by the load balancer.
|
|
*/
|
|
if (env->dst_stats.node_type == node_has_spare) {
|
|
unsigned int imbalance;
|
|
int src_running, dst_running;
|
|
|
|
/*
|
|
* Would movement cause an imbalance? Note that if src has
|
|
* more running tasks that the imbalance is ignored as the
|
|
* move improves the imbalance from the perspective of the
|
|
* CPU load balancer.
|
|
* */
|
|
src_running = env->src_stats.nr_running - 1;
|
|
dst_running = env->dst_stats.nr_running + 1;
|
|
imbalance = max(0, dst_running - src_running);
|
|
imbalance = adjust_numa_imbalance(imbalance, dst_running,
|
|
env->imb_numa_nr);
|
|
|
|
/* Use idle CPU if there is no imbalance */
|
|
if (!imbalance) {
|
|
maymove = true;
|
|
if (env->dst_stats.idle_cpu >= 0) {
|
|
env->dst_cpu = env->dst_stats.idle_cpu;
|
|
task_numa_assign(env, NULL, 0);
|
|
return;
|
|
}
|
|
}
|
|
} else {
|
|
long src_load, dst_load, load;
|
|
/*
|
|
* If the improvement from just moving env->p direction is better
|
|
* than swapping tasks around, check if a move is possible.
|
|
*/
|
|
load = task_h_load(env->p);
|
|
dst_load = env->dst_stats.load + load;
|
|
src_load = env->src_stats.load - load;
|
|
maymove = !load_too_imbalanced(src_load, dst_load, env);
|
|
}
|
|
|
|
for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
|
|
/* Skip this CPU if the source task cannot migrate */
|
|
if (!cpumask_test_cpu(cpu, env->p->cpus_ptr))
|
|
continue;
|
|
|
|
env->dst_cpu = cpu;
|
|
if (task_numa_compare(env, taskimp, groupimp, maymove))
|
|
break;
|
|
}
|
|
}
|
|
|
|
static int task_numa_migrate(struct task_struct *p)
|
|
{
|
|
struct task_numa_env env = {
|
|
.p = p,
|
|
|
|
.src_cpu = task_cpu(p),
|
|
.src_nid = task_node(p),
|
|
|
|
.imbalance_pct = 112,
|
|
|
|
.best_task = NULL,
|
|
.best_imp = 0,
|
|
.best_cpu = -1,
|
|
};
|
|
unsigned long taskweight, groupweight;
|
|
struct sched_domain *sd;
|
|
long taskimp, groupimp;
|
|
struct numa_group *ng;
|
|
struct rq *best_rq;
|
|
int nid, ret, dist;
|
|
|
|
/*
|
|
* Pick the lowest SD_NUMA domain, as that would have the smallest
|
|
* imbalance and would be the first to start moving tasks about.
|
|
*
|
|
* And we want to avoid any moving of tasks about, as that would create
|
|
* random movement of tasks -- counter the numa conditions we're trying
|
|
* to satisfy here.
|
|
*/
|
|
rcu_read_lock();
|
|
sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu));
|
|
if (sd) {
|
|
env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2;
|
|
env.imb_numa_nr = sd->imb_numa_nr;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* Cpusets can break the scheduler domain tree into smaller
|
|
* balance domains, some of which do not cross NUMA boundaries.
|
|
* Tasks that are "trapped" in such domains cannot be migrated
|
|
* elsewhere, so there is no point in (re)trying.
|
|
*/
|
|
if (unlikely(!sd)) {
|
|
sched_setnuma(p, task_node(p));
|
|
return -EINVAL;
|
|
}
|
|
|
|
env.dst_nid = p->numa_preferred_nid;
|
|
dist = env.dist = node_distance(env.src_nid, env.dst_nid);
|
|
taskweight = task_weight(p, env.src_nid, dist);
|
|
groupweight = group_weight(p, env.src_nid, dist);
|
|
update_numa_stats(&env, &env.src_stats, env.src_nid, false);
|
|
taskimp = task_weight(p, env.dst_nid, dist) - taskweight;
|
|
groupimp = group_weight(p, env.dst_nid, dist) - groupweight;
|
|
update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
|
|
|
|
/* Try to find a spot on the preferred nid. */
|
|
task_numa_find_cpu(&env, taskimp, groupimp);
|
|
|
|
/*
|
|
* Look at other nodes in these cases:
|
|
* - there is no space available on the preferred_nid
|
|
* - the task is part of a numa_group that is interleaved across
|
|
* multiple NUMA nodes; in order to better consolidate the group,
|
|
* we need to check other locations.
|
|
*/
|
|
ng = deref_curr_numa_group(p);
|
|
if (env.best_cpu == -1 || (ng && ng->active_nodes > 1)) {
|
|
for_each_node_state(nid, N_CPU) {
|
|
if (nid == env.src_nid || nid == p->numa_preferred_nid)
|
|
continue;
|
|
|
|
dist = node_distance(env.src_nid, env.dst_nid);
|
|
if (sched_numa_topology_type == NUMA_BACKPLANE &&
|
|
dist != env.dist) {
|
|
taskweight = task_weight(p, env.src_nid, dist);
|
|
groupweight = group_weight(p, env.src_nid, dist);
|
|
}
|
|
|
|
/* Only consider nodes where both task and groups benefit */
|
|
taskimp = task_weight(p, nid, dist) - taskweight;
|
|
groupimp = group_weight(p, nid, dist) - groupweight;
|
|
if (taskimp < 0 && groupimp < 0)
|
|
continue;
|
|
|
|
env.dist = dist;
|
|
env.dst_nid = nid;
|
|
update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
|
|
task_numa_find_cpu(&env, taskimp, groupimp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the task is part of a workload that spans multiple NUMA nodes,
|
|
* and is migrating into one of the workload's active nodes, remember
|
|
* this node as the task's preferred numa node, so the workload can
|
|
* settle down.
|
|
* A task that migrated to a second choice node will be better off
|
|
* trying for a better one later. Do not set the preferred node here.
|
|
*/
|
|
if (ng) {
|
|
if (env.best_cpu == -1)
|
|
nid = env.src_nid;
|
|
else
|
|
nid = cpu_to_node(env.best_cpu);
|
|
|
|
if (nid != p->numa_preferred_nid)
|
|
sched_setnuma(p, nid);
|
|
}
|
|
|
|
/* No better CPU than the current one was found. */
|
|
if (env.best_cpu == -1) {
|
|
trace_sched_stick_numa(p, env.src_cpu, NULL, -1);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
best_rq = cpu_rq(env.best_cpu);
|
|
if (env.best_task == NULL) {
|
|
ret = migrate_task_to(p, env.best_cpu);
|
|
WRITE_ONCE(best_rq->numa_migrate_on, 0);
|
|
if (ret != 0)
|
|
trace_sched_stick_numa(p, env.src_cpu, NULL, env.best_cpu);
|
|
return ret;
|
|
}
|
|
|
|
ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu);
|
|
WRITE_ONCE(best_rq->numa_migrate_on, 0);
|
|
|
|
if (ret != 0)
|
|
trace_sched_stick_numa(p, env.src_cpu, env.best_task, env.best_cpu);
|
|
put_task_struct(env.best_task);
|
|
return ret;
|
|
}
|
|
|
|
/* Attempt to migrate a task to a CPU on the preferred node. */
|
|
static void numa_migrate_preferred(struct task_struct *p)
|
|
{
|
|
unsigned long interval = HZ;
|
|
|
|
/* This task has no NUMA fault statistics yet */
|
|
if (unlikely(p->numa_preferred_nid == NUMA_NO_NODE || !p->numa_faults))
|
|
return;
|
|
|
|
/* Periodically retry migrating the task to the preferred node */
|
|
interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
|
|
p->numa_migrate_retry = jiffies + interval;
|
|
|
|
/* Success if task is already running on preferred CPU */
|
|
if (task_node(p) == p->numa_preferred_nid)
|
|
return;
|
|
|
|
/* Otherwise, try migrate to a CPU on the preferred node */
|
|
task_numa_migrate(p);
|
|
}
|
|
|
|
/*
|
|
* Find out how many nodes the workload is actively running on. Do this by
|
|
* tracking the nodes from which NUMA hinting faults are triggered. This can
|
|
* be different from the set of nodes where the workload's memory is currently
|
|
* located.
|
|
*/
|
|
static void numa_group_count_active_nodes(struct numa_group *numa_group)
|
|
{
|
|
unsigned long faults, max_faults = 0;
|
|
int nid, active_nodes = 0;
|
|
|
|
for_each_node_state(nid, N_CPU) {
|
|
faults = group_faults_cpu(numa_group, nid);
|
|
if (faults > max_faults)
|
|
max_faults = faults;
|
|
}
|
|
|
|
for_each_node_state(nid, N_CPU) {
|
|
faults = group_faults_cpu(numa_group, nid);
|
|
if (faults * ACTIVE_NODE_FRACTION > max_faults)
|
|
active_nodes++;
|
|
}
|
|
|
|
numa_group->max_faults_cpu = max_faults;
|
|
numa_group->active_nodes = active_nodes;
|
|
}
|
|
|
|
/*
|
|
* When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS
|
|
* increments. The more local the fault statistics are, the higher the scan
|
|
* period will be for the next scan window. If local/(local+remote) ratio is
|
|
* below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS)
|
|
* the scan period will decrease. Aim for 70% local accesses.
|
|
*/
|
|
#define NUMA_PERIOD_SLOTS 10
|
|
#define NUMA_PERIOD_THRESHOLD 7
|
|
|
|
/*
|
|
* Increase the scan period (slow down scanning) if the majority of
|
|
* our memory is already on our local node, or if the majority of
|
|
* the page accesses are shared with other processes.
|
|
* Otherwise, decrease the scan period.
|
|
*/
|
|
static void update_task_scan_period(struct task_struct *p,
|
|
unsigned long shared, unsigned long private)
|
|
{
|
|
unsigned int period_slot;
|
|
int lr_ratio, ps_ratio;
|
|
int diff;
|
|
|
|
unsigned long remote = p->numa_faults_locality[0];
|
|
unsigned long local = p->numa_faults_locality[1];
|
|
|
|
/*
|
|
* If there were no record hinting faults then either the task is
|
|
* completely idle or all activity is in areas that are not of interest
|
|
* to automatic numa balancing. Related to that, if there were failed
|
|
* migration then it implies we are migrating too quickly or the local
|
|
* node is overloaded. In either case, scan slower
|
|
*/
|
|
if (local + shared == 0 || p->numa_faults_locality[2]) {
|
|
p->numa_scan_period = min(p->numa_scan_period_max,
|
|
p->numa_scan_period << 1);
|
|
|
|
p->mm->numa_next_scan = jiffies +
|
|
msecs_to_jiffies(p->numa_scan_period);
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Prepare to scale scan period relative to the current period.
|
|
* == NUMA_PERIOD_THRESHOLD scan period stays the same
|
|
* < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster)
|
|
* >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower)
|
|
*/
|
|
period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS);
|
|
lr_ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote);
|
|
ps_ratio = (private * NUMA_PERIOD_SLOTS) / (private + shared);
|
|
|
|
if (ps_ratio >= NUMA_PERIOD_THRESHOLD) {
|
|
/*
|
|
* Most memory accesses are local. There is no need to
|
|
* do fast NUMA scanning, since memory is already local.
|
|
*/
|
|
int slot = ps_ratio - NUMA_PERIOD_THRESHOLD;
|
|
if (!slot)
|
|
slot = 1;
|
|
diff = slot * period_slot;
|
|
} else if (lr_ratio >= NUMA_PERIOD_THRESHOLD) {
|
|
/*
|
|
* Most memory accesses are shared with other tasks.
|
|
* There is no point in continuing fast NUMA scanning,
|
|
* since other tasks may just move the memory elsewhere.
|
|
*/
|
|
int slot = lr_ratio - NUMA_PERIOD_THRESHOLD;
|
|
if (!slot)
|
|
slot = 1;
|
|
diff = slot * period_slot;
|
|
} else {
|
|
/*
|
|
* Private memory faults exceed (SLOTS-THRESHOLD)/SLOTS,
|
|
* yet they are not on the local NUMA node. Speed up
|
|
* NUMA scanning to get the memory moved over.
|
|
*/
|
|
int ratio = max(lr_ratio, ps_ratio);
|
|
diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot;
|
|
}
|
|
|
|
p->numa_scan_period = clamp(p->numa_scan_period + diff,
|
|
task_scan_min(p), task_scan_max(p));
|
|
memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
|
|
}
|
|
|
|
/*
|
|
* Get the fraction of time the task has been running since the last
|
|
* NUMA placement cycle. The scheduler keeps similar statistics, but
|
|
* decays those on a 32ms period, which is orders of magnitude off
|
|
* from the dozens-of-seconds NUMA balancing period. Use the scheduler
|
|
* stats only if the task is so new there are no NUMA statistics yet.
|
|
*/
|
|
static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
|
|
{
|
|
u64 runtime, delta, now;
|
|
/* Use the start of this time slice to avoid calculations. */
|
|
now = p->se.exec_start;
|
|
runtime = p->se.sum_exec_runtime;
|
|
|
|
if (p->last_task_numa_placement) {
|
|
delta = runtime - p->last_sum_exec_runtime;
|
|
*period = now - p->last_task_numa_placement;
|
|
|
|
/* Avoid time going backwards, prevent potential divide error: */
|
|
if (unlikely((s64)*period < 0))
|
|
*period = 0;
|
|
} else {
|
|
delta = p->se.avg.load_sum;
|
|
*period = LOAD_AVG_MAX;
|
|
}
|
|
|
|
p->last_sum_exec_runtime = runtime;
|
|
p->last_task_numa_placement = now;
|
|
|
|
return delta;
|
|
}
|
|
|
|
/*
|
|
* Determine the preferred nid for a task in a numa_group. This needs to
|
|
* be done in a way that produces consistent results with group_weight,
|
|
* otherwise workloads might not converge.
|
|
*/
|
|
static int preferred_group_nid(struct task_struct *p, int nid)
|
|
{
|
|
nodemask_t nodes;
|
|
int dist;
|
|
|
|
/* Direct connections between all NUMA nodes. */
|
|
if (sched_numa_topology_type == NUMA_DIRECT)
|
|
return nid;
|
|
|
|
/*
|
|
* On a system with glueless mesh NUMA topology, group_weight
|
|
* scores nodes according to the number of NUMA hinting faults on
|
|
* both the node itself, and on nearby nodes.
|
|
*/
|
|
if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
|
|
unsigned long score, max_score = 0;
|
|
int node, max_node = nid;
|
|
|
|
dist = sched_max_numa_distance;
|
|
|
|
for_each_node_state(node, N_CPU) {
|
|
score = group_weight(p, node, dist);
|
|
if (score > max_score) {
|
|
max_score = score;
|
|
max_node = node;
|
|
}
|
|
}
|
|
return max_node;
|
|
}
|
|
|
|
/*
|
|
* Finding the preferred nid in a system with NUMA backplane
|
|
* interconnect topology is more involved. The goal is to locate
|
|
* tasks from numa_groups near each other in the system, and
|
|
* untangle workloads from different sides of the system. This requires
|
|
* searching down the hierarchy of node groups, recursively searching
|
|
* inside the highest scoring group of nodes. The nodemask tricks
|
|
* keep the complexity of the search down.
|
|
*/
|
|
nodes = node_states[N_CPU];
|
|
for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) {
|
|
unsigned long max_faults = 0;
|
|
nodemask_t max_group = NODE_MASK_NONE;
|
|
int a, b;
|
|
|
|
/* Are there nodes at this distance from each other? */
|
|
if (!find_numa_distance(dist))
|
|
continue;
|
|
|
|
for_each_node_mask(a, nodes) {
|
|
unsigned long faults = 0;
|
|
nodemask_t this_group;
|
|
nodes_clear(this_group);
|
|
|
|
/* Sum group's NUMA faults; includes a==b case. */
|
|
for_each_node_mask(b, nodes) {
|
|
if (node_distance(a, b) < dist) {
|
|
faults += group_faults(p, b);
|
|
node_set(b, this_group);
|
|
node_clear(b, nodes);
|
|
}
|
|
}
|
|
|
|
/* Remember the top group. */
|
|
if (faults > max_faults) {
|
|
max_faults = faults;
|
|
max_group = this_group;
|
|
/*
|
|
* subtle: at the smallest distance there is
|
|
* just one node left in each "group", the
|
|
* winner is the preferred nid.
|
|
*/
|
|
nid = a;
|
|
}
|
|
}
|
|
/* Next round, evaluate the nodes within max_group. */
|
|
if (!max_faults)
|
|
break;
|
|
nodes = max_group;
|
|
}
|
|
return nid;
|
|
}
|
|
|
|
static void task_numa_placement(struct task_struct *p)
|
|
{
|
|
int seq, nid, max_nid = NUMA_NO_NODE;
|
|
unsigned long max_faults = 0;
|
|
unsigned long fault_types[2] = { 0, 0 };
|
|
unsigned long total_faults;
|
|
u64 runtime, period;
|
|
spinlock_t *group_lock = NULL;
|
|
struct numa_group *ng;
|
|
|
|
/*
|
|
* The p->mm->numa_scan_seq field gets updated without
|
|
* exclusive access. Use READ_ONCE() here to ensure
|
|
* that the field is read in a single access:
|
|
*/
|
|
seq = READ_ONCE(p->mm->numa_scan_seq);
|
|
if (p->numa_scan_seq == seq)
|
|
return;
|
|
p->numa_scan_seq = seq;
|
|
p->numa_scan_period_max = task_scan_max(p);
|
|
|
|
total_faults = p->numa_faults_locality[0] +
|
|
p->numa_faults_locality[1];
|
|
runtime = numa_get_avg_runtime(p, &period);
|
|
|
|
/* If the task is part of a group prevent parallel updates to group stats */
|
|
ng = deref_curr_numa_group(p);
|
|
if (ng) {
|
|
group_lock = &ng->lock;
|
|
spin_lock_irq(group_lock);
|
|
}
|
|
|
|
/* Find the node with the highest number of faults */
|
|
for_each_online_node(nid) {
|
|
/* Keep track of the offsets in numa_faults array */
|
|
int mem_idx, membuf_idx, cpu_idx, cpubuf_idx;
|
|
unsigned long faults = 0, group_faults = 0;
|
|
int priv;
|
|
|
|
for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
|
|
long diff, f_diff, f_weight;
|
|
|
|
mem_idx = task_faults_idx(NUMA_MEM, nid, priv);
|
|
membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv);
|
|
cpu_idx = task_faults_idx(NUMA_CPU, nid, priv);
|
|
cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv);
|
|
|
|
/* Decay existing window, copy faults since last scan */
|
|
diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2;
|
|
fault_types[priv] += p->numa_faults[membuf_idx];
|
|
p->numa_faults[membuf_idx] = 0;
|
|
|
|
/*
|
|
* Normalize the faults_from, so all tasks in a group
|
|
* count according to CPU use, instead of by the raw
|
|
* number of faults. Tasks with little runtime have
|
|
* little over-all impact on throughput, and thus their
|
|
* faults are less important.
|
|
*/
|
|
f_weight = div64_u64(runtime << 16, period + 1);
|
|
f_weight = (f_weight * p->numa_faults[cpubuf_idx]) /
|
|
(total_faults + 1);
|
|
f_diff = f_weight - p->numa_faults[cpu_idx] / 2;
|
|
p->numa_faults[cpubuf_idx] = 0;
|
|
|
|
p->numa_faults[mem_idx] += diff;
|
|
p->numa_faults[cpu_idx] += f_diff;
|
|
faults += p->numa_faults[mem_idx];
|
|
p->total_numa_faults += diff;
|
|
if (ng) {
|
|
/*
|
|
* safe because we can only change our own group
|
|
*
|
|
* mem_idx represents the offset for a given
|
|
* nid and priv in a specific region because it
|
|
* is at the beginning of the numa_faults array.
|
|
*/
|
|
ng->faults[mem_idx] += diff;
|
|
ng->faults[cpu_idx] += f_diff;
|
|
ng->total_faults += diff;
|
|
group_faults += ng->faults[mem_idx];
|
|
}
|
|
}
|
|
|
|
if (!ng) {
|
|
if (faults > max_faults) {
|
|
max_faults = faults;
|
|
max_nid = nid;
|
|
}
|
|
} else if (group_faults > max_faults) {
|
|
max_faults = group_faults;
|
|
max_nid = nid;
|
|
}
|
|
}
|
|
|
|
/* Cannot migrate task to CPU-less node */
|
|
max_nid = numa_nearest_node(max_nid, N_CPU);
|
|
|
|
if (ng) {
|
|
numa_group_count_active_nodes(ng);
|
|
spin_unlock_irq(group_lock);
|
|
max_nid = preferred_group_nid(p, max_nid);
|
|
}
|
|
|
|
if (max_faults) {
|
|
/* Set the new preferred node */
|
|
if (max_nid != p->numa_preferred_nid)
|
|
sched_setnuma(p, max_nid);
|
|
}
|
|
|
|
update_task_scan_period(p, fault_types[0], fault_types[1]);
|
|
}
|
|
|
|
static inline int get_numa_group(struct numa_group *grp)
|
|
{
|
|
return refcount_inc_not_zero(&grp->refcount);
|
|
}
|
|
|
|
static inline void put_numa_group(struct numa_group *grp)
|
|
{
|
|
if (refcount_dec_and_test(&grp->refcount))
|
|
kfree_rcu(grp, rcu);
|
|
}
|
|
|
|
static void task_numa_group(struct task_struct *p, int cpupid, int flags,
|
|
int *priv)
|
|
{
|
|
struct numa_group *grp, *my_grp;
|
|
struct task_struct *tsk;
|
|
bool join = false;
|
|
int cpu = cpupid_to_cpu(cpupid);
|
|
int i;
|
|
|
|
if (unlikely(!deref_curr_numa_group(p))) {
|
|
unsigned int size = sizeof(struct numa_group) +
|
|
NR_NUMA_HINT_FAULT_STATS *
|
|
nr_node_ids * sizeof(unsigned long);
|
|
|
|
grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
|
|
if (!grp)
|
|
return;
|
|
|
|
refcount_set(&grp->refcount, 1);
|
|
grp->active_nodes = 1;
|
|
grp->max_faults_cpu = 0;
|
|
spin_lock_init(&grp->lock);
|
|
grp->gid = p->pid;
|
|
|
|
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
|
|
grp->faults[i] = p->numa_faults[i];
|
|
|
|
grp->total_faults = p->total_numa_faults;
|
|
|
|
grp->nr_tasks++;
|
|
rcu_assign_pointer(p->numa_group, grp);
|
|
}
|
|
|
|
rcu_read_lock();
|
|
tsk = READ_ONCE(cpu_rq(cpu)->curr);
|
|
|
|
if (!cpupid_match_pid(tsk, cpupid))
|
|
goto no_join;
|
|
|
|
grp = rcu_dereference(tsk->numa_group);
|
|
if (!grp)
|
|
goto no_join;
|
|
|
|
my_grp = deref_curr_numa_group(p);
|
|
if (grp == my_grp)
|
|
goto no_join;
|
|
|
|
/*
|
|
* Only join the other group if its bigger; if we're the bigger group,
|
|
* the other task will join us.
|
|
*/
|
|
if (my_grp->nr_tasks > grp->nr_tasks)
|
|
goto no_join;
|
|
|
|
/*
|
|
* Tie-break on the grp address.
|
|
*/
|
|
if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp)
|
|
goto no_join;
|
|
|
|
/* Always join threads in the same process. */
|
|
if (tsk->mm == current->mm)
|
|
join = true;
|
|
|
|
/* Simple filter to avoid false positives due to PID collisions */
|
|
if (flags & TNF_SHARED)
|
|
join = true;
|
|
|
|
/* Update priv based on whether false sharing was detected */
|
|
*priv = !join;
|
|
|
|
if (join && !get_numa_group(grp))
|
|
goto no_join;
|
|
|
|
rcu_read_unlock();
|
|
|
|
if (!join)
|
|
return;
|
|
|
|
WARN_ON_ONCE(irqs_disabled());
|
|
double_lock_irq(&my_grp->lock, &grp->lock);
|
|
|
|
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
|
|
my_grp->faults[i] -= p->numa_faults[i];
|
|
grp->faults[i] += p->numa_faults[i];
|
|
}
|
|
my_grp->total_faults -= p->total_numa_faults;
|
|
grp->total_faults += p->total_numa_faults;
|
|
|
|
my_grp->nr_tasks--;
|
|
grp->nr_tasks++;
|
|
|
|
spin_unlock(&my_grp->lock);
|
|
spin_unlock_irq(&grp->lock);
|
|
|
|
rcu_assign_pointer(p->numa_group, grp);
|
|
|
|
put_numa_group(my_grp);
|
|
return;
|
|
|
|
no_join:
|
|
rcu_read_unlock();
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Get rid of NUMA statistics associated with a task (either current or dead).
|
|
* If @final is set, the task is dead and has reached refcount zero, so we can
|
|
* safely free all relevant data structures. Otherwise, there might be
|
|
* concurrent reads from places like load balancing and procfs, and we should
|
|
* reset the data back to default state without freeing ->numa_faults.
|
|
*/
|
|
void task_numa_free(struct task_struct *p, bool final)
|
|
{
|
|
/* safe: p either is current or is being freed by current */
|
|
struct numa_group *grp = rcu_dereference_raw(p->numa_group);
|
|
unsigned long *numa_faults = p->numa_faults;
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
if (!numa_faults)
|
|
return;
|
|
|
|
if (grp) {
|
|
spin_lock_irqsave(&grp->lock, flags);
|
|
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
|
|
grp->faults[i] -= p->numa_faults[i];
|
|
grp->total_faults -= p->total_numa_faults;
|
|
|
|
grp->nr_tasks--;
|
|
spin_unlock_irqrestore(&grp->lock, flags);
|
|
RCU_INIT_POINTER(p->numa_group, NULL);
|
|
put_numa_group(grp);
|
|
}
|
|
|
|
if (final) {
|
|
p->numa_faults = NULL;
|
|
kfree(numa_faults);
|
|
} else {
|
|
p->total_numa_faults = 0;
|
|
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
|
|
numa_faults[i] = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Got a PROT_NONE fault for a page on @node.
|
|
*/
|
|
void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
|
|
{
|
|
struct task_struct *p = current;
|
|
bool migrated = flags & TNF_MIGRATED;
|
|
int cpu_node = task_node(current);
|
|
int local = !!(flags & TNF_FAULT_LOCAL);
|
|
struct numa_group *ng;
|
|
int priv;
|
|
|
|
if (!static_branch_likely(&sched_numa_balancing))
|
|
return;
|
|
|
|
/* for example, ksmd faulting in a user's mm */
|
|
if (!p->mm)
|
|
return;
|
|
|
|
/*
|
|
* NUMA faults statistics are unnecessary for the slow memory
|
|
* node for memory tiering mode.
|
|
*/
|
|
if (!node_is_toptier(mem_node) &&
|
|
(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ||
|
|
!cpupid_valid(last_cpupid)))
|
|
return;
|
|
|
|
/* Allocate buffer to track faults on a per-node basis */
|
|
if (unlikely(!p->numa_faults)) {
|
|
int size = sizeof(*p->numa_faults) *
|
|
NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;
|
|
|
|
p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
|
|
if (!p->numa_faults)
|
|
return;
|
|
|
|
p->total_numa_faults = 0;
|
|
memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
|
|
}
|
|
|
|
/*
|
|
* First accesses are treated as private, otherwise consider accesses
|
|
* to be private if the accessing pid has not changed
|
|
*/
|
|
if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) {
|
|
priv = 1;
|
|
} else {
|
|
priv = cpupid_match_pid(p, last_cpupid);
|
|
if (!priv && !(flags & TNF_NO_GROUP))
|
|
task_numa_group(p, last_cpupid, flags, &priv);
|
|
}
|
|
|
|
/*
|
|
* If a workload spans multiple NUMA nodes, a shared fault that
|
|
* occurs wholly within the set of nodes that the workload is
|
|
* actively using should be counted as local. This allows the
|
|
* scan rate to slow down when a workload has settled down.
|
|
*/
|
|
ng = deref_curr_numa_group(p);
|
|
if (!priv && !local && ng && ng->active_nodes > 1 &&
|
|
numa_is_active_node(cpu_node, ng) &&
|
|
numa_is_active_node(mem_node, ng))
|
|
local = 1;
|
|
|
|
/*
|
|
* Retry to migrate task to preferred node periodically, in case it
|
|
* previously failed, or the scheduler moved us.
|
|
*/
|
|
if (time_after(jiffies, p->numa_migrate_retry)) {
|
|
task_numa_placement(p);
|
|
numa_migrate_preferred(p);
|
|
}
|
|
|
|
if (migrated)
|
|
p->numa_pages_migrated += pages;
|
|
if (flags & TNF_MIGRATE_FAIL)
|
|
p->numa_faults_locality[2] += pages;
|
|
|
|
p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages;
|
|
p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages;
|
|
p->numa_faults_locality[local] += pages;
|
|
}
|
|
|
|
static void reset_ptenuma_scan(struct task_struct *p)
|
|
{
|
|
/*
|
|
* We only did a read acquisition of the mmap sem, so
|
|
* p->mm->numa_scan_seq is written to without exclusive access
|
|
* and the update is not guaranteed to be atomic. That's not
|
|
* much of an issue though, since this is just used for
|
|
* statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not
|
|
* expensive, to avoid any form of compiler optimizations:
|
|
*/
|
|
WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1);
|
|
p->mm->numa_scan_offset = 0;
|
|
}
|
|
|
|
static bool vma_is_accessed(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long pids;
|
|
/*
|
|
* Allow unconditional access first two times, so that all the (pages)
|
|
* of VMAs get prot_none fault introduced irrespective of accesses.
|
|
* This is also done to avoid any side effect of task scanning
|
|
* amplifying the unfairness of disjoint set of VMAs' access.
|
|
*/
|
|
if ((READ_ONCE(current->mm->numa_scan_seq) - vma->numab_state->start_scan_seq) < 2)
|
|
return true;
|
|
|
|
pids = vma->numab_state->pids_active[0] | vma->numab_state->pids_active[1];
|
|
if (test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids))
|
|
return true;
|
|
|
|
/*
|
|
* Complete a scan that has already started regardless of PID access, or
|
|
* some VMAs may never be scanned in multi-threaded applications:
|
|
*/
|
|
if (mm->numa_scan_offset > vma->vm_start) {
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_IGNORE_PID);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
#define VMA_PID_RESET_PERIOD (4 * sysctl_numa_balancing_scan_delay)
|
|
|
|
/*
|
|
* The expensive part of numa migration is done from task_work context.
|
|
* Triggered from task_tick_numa().
|
|
*/
|
|
static void task_numa_work(struct callback_head *work)
|
|
{
|
|
unsigned long migrate, next_scan, now = jiffies;
|
|
struct task_struct *p = current;
|
|
struct mm_struct *mm = p->mm;
|
|
u64 runtime = p->se.sum_exec_runtime;
|
|
struct vm_area_struct *vma;
|
|
unsigned long start, end;
|
|
unsigned long nr_pte_updates = 0;
|
|
long pages, virtpages;
|
|
struct vma_iterator vmi;
|
|
bool vma_pids_skipped;
|
|
bool vma_pids_forced = false;
|
|
|
|
SCHED_WARN_ON(p != container_of(work, struct task_struct, numa_work));
|
|
|
|
work->next = work;
|
|
/*
|
|
* Who cares about NUMA placement when they're dying.
|
|
*
|
|
* NOTE: make sure not to dereference p->mm before this check,
|
|
* exit_task_work() happens _after_ exit_mm() so we could be called
|
|
* without p->mm even though we still had it when we enqueued this
|
|
* work.
|
|
*/
|
|
if (p->flags & PF_EXITING)
|
|
return;
|
|
|
|
if (!mm->numa_next_scan) {
|
|
mm->numa_next_scan = now +
|
|
msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
|
|
}
|
|
|
|
/*
|
|
* Enforce maximal scan/migration frequency..
|
|
*/
|
|
migrate = mm->numa_next_scan;
|
|
if (time_before(now, migrate))
|
|
return;
|
|
|
|
if (p->numa_scan_period == 0) {
|
|
p->numa_scan_period_max = task_scan_max(p);
|
|
p->numa_scan_period = task_scan_start(p);
|
|
}
|
|
|
|
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
|
|
if (!try_cmpxchg(&mm->numa_next_scan, &migrate, next_scan))
|
|
return;
|
|
|
|
/*
|
|
* Delay this task enough that another task of this mm will likely win
|
|
* the next time around.
|
|
*/
|
|
p->node_stamp += 2 * TICK_NSEC;
|
|
|
|
pages = sysctl_numa_balancing_scan_size;
|
|
pages <<= 20 - PAGE_SHIFT; /* MB in pages */
|
|
virtpages = pages * 8; /* Scan up to this much virtual space */
|
|
if (!pages)
|
|
return;
|
|
|
|
|
|
if (!mmap_read_trylock(mm))
|
|
return;
|
|
|
|
/*
|
|
* VMAs are skipped if the current PID has not trapped a fault within
|
|
* the VMA recently. Allow scanning to be forced if there is no
|
|
* suitable VMA remaining.
|
|
*/
|
|
vma_pids_skipped = false;
|
|
|
|
retry_pids:
|
|
start = mm->numa_scan_offset;
|
|
vma_iter_init(&vmi, mm, start);
|
|
vma = vma_next(&vmi);
|
|
if (!vma) {
|
|
reset_ptenuma_scan(p);
|
|
start = 0;
|
|
vma_iter_set(&vmi, start);
|
|
vma = vma_next(&vmi);
|
|
}
|
|
|
|
do {
|
|
if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
|
|
is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_UNSUITABLE);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Shared library pages mapped by multiple processes are not
|
|
* migrated as it is expected they are cache replicated. Avoid
|
|
* hinting faults in read-only file-backed mappings or the vdso
|
|
* as migrating the pages will be of marginal benefit.
|
|
*/
|
|
if (!vma->vm_mm ||
|
|
(vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) {
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SHARED_RO);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Skip inaccessible VMAs to avoid any confusion between
|
|
* PROT_NONE and NUMA hinting ptes
|
|
*/
|
|
if (!vma_is_accessible(vma)) {
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_INACCESSIBLE);
|
|
continue;
|
|
}
|
|
|
|
/* Initialise new per-VMA NUMAB state. */
|
|
if (!vma->numab_state) {
|
|
vma->numab_state = kzalloc(sizeof(struct vma_numab_state),
|
|
GFP_KERNEL);
|
|
if (!vma->numab_state)
|
|
continue;
|
|
|
|
vma->numab_state->start_scan_seq = mm->numa_scan_seq;
|
|
|
|
vma->numab_state->next_scan = now +
|
|
msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
|
|
|
|
/* Reset happens after 4 times scan delay of scan start */
|
|
vma->numab_state->pids_active_reset = vma->numab_state->next_scan +
|
|
msecs_to_jiffies(VMA_PID_RESET_PERIOD);
|
|
|
|
/*
|
|
* Ensure prev_scan_seq does not match numa_scan_seq,
|
|
* to prevent VMAs being skipped prematurely on the
|
|
* first scan:
|
|
*/
|
|
vma->numab_state->prev_scan_seq = mm->numa_scan_seq - 1;
|
|
}
|
|
|
|
/*
|
|
* Scanning the VMA's of short lived tasks add more overhead. So
|
|
* delay the scan for new VMAs.
|
|
*/
|
|
if (mm->numa_scan_seq && time_before(jiffies,
|
|
vma->numab_state->next_scan)) {
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SCAN_DELAY);
|
|
continue;
|
|
}
|
|
|
|
/* RESET access PIDs regularly for old VMAs. */
|
|
if (mm->numa_scan_seq &&
|
|
time_after(jiffies, vma->numab_state->pids_active_reset)) {
|
|
vma->numab_state->pids_active_reset = vma->numab_state->pids_active_reset +
|
|
msecs_to_jiffies(VMA_PID_RESET_PERIOD);
|
|
vma->numab_state->pids_active[0] = READ_ONCE(vma->numab_state->pids_active[1]);
|
|
vma->numab_state->pids_active[1] = 0;
|
|
}
|
|
|
|
/* Do not rescan VMAs twice within the same sequence. */
|
|
if (vma->numab_state->prev_scan_seq == mm->numa_scan_seq) {
|
|
mm->numa_scan_offset = vma->vm_end;
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SEQ_COMPLETED);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Do not scan the VMA if task has not accessed it, unless no other
|
|
* VMA candidate exists.
|
|
*/
|
|
if (!vma_pids_forced && !vma_is_accessed(mm, vma)) {
|
|
vma_pids_skipped = true;
|
|
trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE);
|
|
continue;
|
|
}
|
|
|
|
do {
|
|
start = max(start, vma->vm_start);
|
|
end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
|
|
end = min(end, vma->vm_end);
|
|
nr_pte_updates = change_prot_numa(vma, start, end);
|
|
|
|
/*
|
|
* Try to scan sysctl_numa_balancing_size worth of
|
|
* hpages that have at least one present PTE that
|
|
* is not already pte-numa. If the VMA contains
|
|
* areas that are unused or already full of prot_numa
|
|
* PTEs, scan up to virtpages, to skip through those
|
|
* areas faster.
|
|
*/
|
|
if (nr_pte_updates)
|
|
pages -= (end - start) >> PAGE_SHIFT;
|
|
virtpages -= (end - start) >> PAGE_SHIFT;
|
|
|
|
start = end;
|
|
if (pages <= 0 || virtpages <= 0)
|
|
goto out;
|
|
|
|
cond_resched();
|
|
} while (end != vma->vm_end);
|
|
|
|
/* VMA scan is complete, do not scan until next sequence. */
|
|
vma->numab_state->prev_scan_seq = mm->numa_scan_seq;
|
|
|
|
/*
|
|
* Only force scan within one VMA at a time, to limit the
|
|
* cost of scanning a potentially uninteresting VMA.
|
|
*/
|
|
if (vma_pids_forced)
|
|
break;
|
|
} for_each_vma(vmi, vma);
|
|
|
|
/*
|
|
* If no VMAs are remaining and VMAs were skipped due to the PID
|
|
* not accessing the VMA previously, then force a scan to ensure
|
|
* forward progress:
|
|
*/
|
|
if (!vma && !vma_pids_forced && vma_pids_skipped) {
|
|
vma_pids_forced = true;
|
|
goto retry_pids;
|
|
}
|
|
|
|
out:
|
|
/*
|
|
* It is possible to reach the end of the VMA list but the last few
|
|
* VMAs are not guaranteed to the vma_migratable. If they are not, we
|
|
* would find the !migratable VMA on the next scan but not reset the
|
|
* scanner to the start so check it now.
|
|
*/
|
|
if (vma)
|
|
mm->numa_scan_offset = start;
|
|
else
|
|
reset_ptenuma_scan(p);
|
|
mmap_read_unlock(mm);
|
|
|
|
/*
|
|
* Make sure tasks use at least 32x as much time to run other code
|
|
* than they used here, to limit NUMA PTE scanning overhead to 3% max.
|
|
* Usually update_task_scan_period slows down scanning enough; on an
|
|
* overloaded system we need to limit overhead on a per task basis.
|
|
*/
|
|
if (unlikely(p->se.sum_exec_runtime != runtime)) {
|
|
u64 diff = p->se.sum_exec_runtime - runtime;
|
|
p->node_stamp += 32 * diff;
|
|
}
|
|
}
|
|
|
|
void init_numa_balancing(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
int mm_users = 0;
|
|
struct mm_struct *mm = p->mm;
|
|
|
|
if (mm) {
|
|
mm_users = atomic_read(&mm->mm_users);
|
|
if (mm_users == 1) {
|
|
mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
|
|
mm->numa_scan_seq = 0;
|
|
}
|
|
}
|
|
p->node_stamp = 0;
|
|
p->numa_scan_seq = mm ? mm->numa_scan_seq : 0;
|
|
p->numa_scan_period = sysctl_numa_balancing_scan_delay;
|
|
p->numa_migrate_retry = 0;
|
|
/* Protect against double add, see task_tick_numa and task_numa_work */
|
|
p->numa_work.next = &p->numa_work;
|
|
p->numa_faults = NULL;
|
|
p->numa_pages_migrated = 0;
|
|
p->total_numa_faults = 0;
|
|
RCU_INIT_POINTER(p->numa_group, NULL);
|
|
p->last_task_numa_placement = 0;
|
|
p->last_sum_exec_runtime = 0;
|
|
|
|
init_task_work(&p->numa_work, task_numa_work);
|
|
|
|
/* New address space, reset the preferred nid */
|
|
if (!(clone_flags & CLONE_VM)) {
|
|
p->numa_preferred_nid = NUMA_NO_NODE;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* New thread, keep existing numa_preferred_nid which should be copied
|
|
* already by arch_dup_task_struct but stagger when scans start.
|
|
*/
|
|
if (mm) {
|
|
unsigned int delay;
|
|
|
|
delay = min_t(unsigned int, task_scan_max(current),
|
|
current->numa_scan_period * mm_users * NSEC_PER_MSEC);
|
|
delay += 2 * TICK_NSEC;
|
|
p->node_stamp = delay;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Drive the periodic memory faults..
|
|
*/
|
|
static void task_tick_numa(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
struct callback_head *work = &curr->numa_work;
|
|
u64 period, now;
|
|
|
|
/*
|
|
* We don't care about NUMA placement if we don't have memory.
|
|
*/
|
|
if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work)
|
|
return;
|
|
|
|
/*
|
|
* Using runtime rather than walltime has the dual advantage that
|
|
* we (mostly) drive the selection from busy threads and that the
|
|
* task needs to have done some actual work before we bother with
|
|
* NUMA placement.
|
|
*/
|
|
now = curr->se.sum_exec_runtime;
|
|
period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
|
|
|
|
if (now > curr->node_stamp + period) {
|
|
if (!curr->node_stamp)
|
|
curr->numa_scan_period = task_scan_start(curr);
|
|
curr->node_stamp += period;
|
|
|
|
if (!time_before(jiffies, curr->mm->numa_next_scan))
|
|
task_work_add(curr, work, TWA_RESUME);
|
|
}
|
|
}
|
|
|
|
static void update_scan_period(struct task_struct *p, int new_cpu)
|
|
{
|
|
int src_nid = cpu_to_node(task_cpu(p));
|
|
int dst_nid = cpu_to_node(new_cpu);
|
|
|
|
if (!static_branch_likely(&sched_numa_balancing))
|
|
return;
|
|
|
|
if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING))
|
|
return;
|
|
|
|
if (src_nid == dst_nid)
|
|
return;
|
|
|
|
/*
|
|
* Allow resets if faults have been trapped before one scan
|
|
* has completed. This is most likely due to a new task that
|
|
* is pulled cross-node due to wakeups or load balancing.
|
|
*/
|
|
if (p->numa_scan_seq) {
|
|
/*
|
|
* Avoid scan adjustments if moving to the preferred
|
|
* node or if the task was not previously running on
|
|
* the preferred node.
|
|
*/
|
|
if (dst_nid == p->numa_preferred_nid ||
|
|
(p->numa_preferred_nid != NUMA_NO_NODE &&
|
|
src_nid != p->numa_preferred_nid))
|
|
return;
|
|
}
|
|
|
|
p->numa_scan_period = task_scan_start(p);
|
|
}
|
|
|
|
#else
|
|
static void task_tick_numa(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
}
|
|
|
|
static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline void update_scan_period(struct task_struct *p, int new_cpu)
|
|
{
|
|
}
|
|
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
static void
|
|
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_add(&cfs_rq->load, se->load.weight);
|
|
#ifdef CONFIG_SMP
|
|
if (entity_is_task(se)) {
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
account_numa_enqueue(rq, task_of(se));
|
|
list_add(&se->group_node, &rq->cfs_tasks);
|
|
}
|
|
#endif
|
|
cfs_rq->nr_running++;
|
|
if (se_is_idle(se))
|
|
cfs_rq->idle_nr_running++;
|
|
}
|
|
|
|
static void
|
|
account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_sub(&cfs_rq->load, se->load.weight);
|
|
#ifdef CONFIG_SMP
|
|
if (entity_is_task(se)) {
|
|
account_numa_dequeue(rq_of(cfs_rq), task_of(se));
|
|
list_del_init(&se->group_node);
|
|
}
|
|
#endif
|
|
cfs_rq->nr_running--;
|
|
if (se_is_idle(se))
|
|
cfs_rq->idle_nr_running--;
|
|
}
|
|
|
|
/*
|
|
* Signed add and clamp on underflow.
|
|
*
|
|
* Explicitly do a load-store to ensure the intermediate value never hits
|
|
* memory. This allows lockless observations without ever seeing the negative
|
|
* values.
|
|
*/
|
|
#define add_positive(_ptr, _val) do { \
|
|
typeof(_ptr) ptr = (_ptr); \
|
|
typeof(_val) val = (_val); \
|
|
typeof(*ptr) res, var = READ_ONCE(*ptr); \
|
|
\
|
|
res = var + val; \
|
|
\
|
|
if (val < 0 && res > var) \
|
|
res = 0; \
|
|
\
|
|
WRITE_ONCE(*ptr, res); \
|
|
} while (0)
|
|
|
|
/*
|
|
* Unsigned subtract and clamp on underflow.
|
|
*
|
|
* Explicitly do a load-store to ensure the intermediate value never hits
|
|
* memory. This allows lockless observations without ever seeing the negative
|
|
* values.
|
|
*/
|
|
#define sub_positive(_ptr, _val) do { \
|
|
typeof(_ptr) ptr = (_ptr); \
|
|
typeof(*ptr) val = (_val); \
|
|
typeof(*ptr) res, var = READ_ONCE(*ptr); \
|
|
res = var - val; \
|
|
if (res > var) \
|
|
res = 0; \
|
|
WRITE_ONCE(*ptr, res); \
|
|
} while (0)
|
|
|
|
/*
|
|
* Remove and clamp on negative, from a local variable.
|
|
*
|
|
* A variant of sub_positive(), which does not use explicit load-store
|
|
* and is thus optimized for local variable updates.
|
|
*/
|
|
#define lsub_positive(_ptr, _val) do { \
|
|
typeof(_ptr) ptr = (_ptr); \
|
|
*ptr -= min_t(typeof(*ptr), *ptr, _val); \
|
|
} while (0)
|
|
|
|
#ifdef CONFIG_SMP
|
|
static inline void
|
|
enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
cfs_rq->avg.load_avg += se->avg.load_avg;
|
|
cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
|
|
}
|
|
|
|
static inline void
|
|
dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
|
|
sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
|
|
cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
|
|
}
|
|
#else
|
|
static inline void
|
|
enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
|
|
static inline void
|
|
dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
|
|
#endif
|
|
|
|
static void reweight_eevdf(struct sched_entity *se, u64 avruntime,
|
|
unsigned long weight)
|
|
{
|
|
unsigned long old_weight = se->load.weight;
|
|
s64 vlag, vslice;
|
|
|
|
/*
|
|
* VRUNTIME
|
|
* ========
|
|
*
|
|
* COROLLARY #1: The virtual runtime of the entity needs to be
|
|
* adjusted if re-weight at !0-lag point.
|
|
*
|
|
* Proof: For contradiction assume this is not true, so we can
|
|
* re-weight without changing vruntime at !0-lag point.
|
|
*
|
|
* Weight VRuntime Avg-VRuntime
|
|
* before w v V
|
|
* after w' v' V'
|
|
*
|
|
* Since lag needs to be preserved through re-weight:
|
|
*
|
|
* lag = (V - v)*w = (V'- v')*w', where v = v'
|
|
* ==> V' = (V - v)*w/w' + v (1)
|
|
*
|
|
* Let W be the total weight of the entities before reweight,
|
|
* since V' is the new weighted average of entities:
|
|
*
|
|
* V' = (WV + w'v - wv) / (W + w' - w) (2)
|
|
*
|
|
* by using (1) & (2) we obtain:
|
|
*
|
|
* (WV + w'v - wv) / (W + w' - w) = (V - v)*w/w' + v
|
|
* ==> (WV-Wv+Wv+w'v-wv)/(W+w'-w) = (V - v)*w/w' + v
|
|
* ==> (WV - Wv)/(W + w' - w) + v = (V - v)*w/w' + v
|
|
* ==> (V - v)*W/(W + w' - w) = (V - v)*w/w' (3)
|
|
*
|
|
* Since we are doing at !0-lag point which means V != v, we
|
|
* can simplify (3):
|
|
*
|
|
* ==> W / (W + w' - w) = w / w'
|
|
* ==> Ww' = Ww + ww' - ww
|
|
* ==> W * (w' - w) = w * (w' - w)
|
|
* ==> W = w (re-weight indicates w' != w)
|
|
*
|
|
* So the cfs_rq contains only one entity, hence vruntime of
|
|
* the entity @v should always equal to the cfs_rq's weighted
|
|
* average vruntime @V, which means we will always re-weight
|
|
* at 0-lag point, thus breach assumption. Proof completed.
|
|
*
|
|
*
|
|
* COROLLARY #2: Re-weight does NOT affect weighted average
|
|
* vruntime of all the entities.
|
|
*
|
|
* Proof: According to corollary #1, Eq. (1) should be:
|
|
*
|
|
* (V - v)*w = (V' - v')*w'
|
|
* ==> v' = V' - (V - v)*w/w' (4)
|
|
*
|
|
* According to the weighted average formula, we have:
|
|
*
|
|
* V' = (WV - wv + w'v') / (W - w + w')
|
|
* = (WV - wv + w'(V' - (V - v)w/w')) / (W - w + w')
|
|
* = (WV - wv + w'V' - Vw + wv) / (W - w + w')
|
|
* = (WV + w'V' - Vw) / (W - w + w')
|
|
*
|
|
* ==> V'*(W - w + w') = WV + w'V' - Vw
|
|
* ==> V' * (W - w) = (W - w) * V (5)
|
|
*
|
|
* If the entity is the only one in the cfs_rq, then reweight
|
|
* always occurs at 0-lag point, so V won't change. Or else
|
|
* there are other entities, hence W != w, then Eq. (5) turns
|
|
* into V' = V. So V won't change in either case, proof done.
|
|
*
|
|
*
|
|
* So according to corollary #1 & #2, the effect of re-weight
|
|
* on vruntime should be:
|
|
*
|
|
* v' = V' - (V - v) * w / w' (4)
|
|
* = V - (V - v) * w / w'
|
|
* = V - vl * w / w'
|
|
* = V - vl'
|
|
*/
|
|
if (avruntime != se->vruntime) {
|
|
vlag = (s64)(avruntime - se->vruntime);
|
|
vlag = div_s64(vlag * old_weight, weight);
|
|
se->vruntime = avruntime - vlag;
|
|
}
|
|
|
|
/*
|
|
* DEADLINE
|
|
* ========
|
|
*
|
|
* When the weight changes, the virtual time slope changes and
|
|
* we should adjust the relative virtual deadline accordingly.
|
|
*
|
|
* d' = v' + (d - v)*w/w'
|
|
* = V' - (V - v)*w/w' + (d - v)*w/w'
|
|
* = V - (V - v)*w/w' + (d - v)*w/w'
|
|
* = V + (d - V)*w/w'
|
|
*/
|
|
vslice = (s64)(se->deadline - avruntime);
|
|
vslice = div_s64(vslice * old_weight, weight);
|
|
se->deadline = avruntime + vslice;
|
|
}
|
|
|
|
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
|
|
unsigned long weight)
|
|
{
|
|
bool curr = cfs_rq->curr == se;
|
|
u64 avruntime;
|
|
|
|
if (se->on_rq) {
|
|
/* commit outstanding execution time */
|
|
update_curr(cfs_rq);
|
|
avruntime = avg_vruntime(cfs_rq);
|
|
if (!curr)
|
|
__dequeue_entity(cfs_rq, se);
|
|
update_load_sub(&cfs_rq->load, se->load.weight);
|
|
}
|
|
dequeue_load_avg(cfs_rq, se);
|
|
|
|
if (se->on_rq) {
|
|
reweight_eevdf(se, avruntime, weight);
|
|
} else {
|
|
/*
|
|
* Because we keep se->vlag = V - v_i, while: lag_i = w_i*(V - v_i),
|
|
* we need to scale se->vlag when w_i changes.
|
|
*/
|
|
se->vlag = div_s64(se->vlag * se->load.weight, weight);
|
|
}
|
|
|
|
update_load_set(&se->load, weight);
|
|
|
|
#ifdef CONFIG_SMP
|
|
do {
|
|
u32 divider = get_pelt_divider(&se->avg);
|
|
|
|
se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
|
|
} while (0);
|
|
#endif
|
|
|
|
enqueue_load_avg(cfs_rq, se);
|
|
if (se->on_rq) {
|
|
update_load_add(&cfs_rq->load, se->load.weight);
|
|
if (!curr)
|
|
__enqueue_entity(cfs_rq, se);
|
|
|
|
/*
|
|
* The entity's vruntime has been adjusted, so let's check
|
|
* whether the rq-wide min_vruntime needs updated too. Since
|
|
* the calculations above require stable min_vruntime rather
|
|
* than up-to-date one, we do the update at the end of the
|
|
* reweight process.
|
|
*/
|
|
update_min_vruntime(cfs_rq);
|
|
}
|
|
}
|
|
|
|
void reweight_task(struct task_struct *p, int prio)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
struct load_weight *load = &se->load;
|
|
unsigned long weight = scale_load(sched_prio_to_weight[prio]);
|
|
|
|
reweight_entity(cfs_rq, se, weight);
|
|
load->inv_weight = sched_prio_to_wmult[prio];
|
|
}
|
|
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* All this does is approximate the hierarchical proportion which includes that
|
|
* global sum we all love to hate.
|
|
*
|
|
* That is, the weight of a group entity, is the proportional share of the
|
|
* group weight based on the group runqueue weights. That is:
|
|
*
|
|
* tg->weight * grq->load.weight
|
|
* ge->load.weight = ----------------------------- (1)
|
|
* \Sum grq->load.weight
|
|
*
|
|
* Now, because computing that sum is prohibitively expensive to compute (been
|
|
* there, done that) we approximate it with this average stuff. The average
|
|
* moves slower and therefore the approximation is cheaper and more stable.
|
|
*
|
|
* So instead of the above, we substitute:
|
|
*
|
|
* grq->load.weight -> grq->avg.load_avg (2)
|
|
*
|
|
* which yields the following:
|
|
*
|
|
* tg->weight * grq->avg.load_avg
|
|
* ge->load.weight = ------------------------------ (3)
|
|
* tg->load_avg
|
|
*
|
|
* Where: tg->load_avg ~= \Sum grq->avg.load_avg
|
|
*
|
|
* That is shares_avg, and it is right (given the approximation (2)).
|
|
*
|
|
* The problem with it is that because the average is slow -- it was designed
|
|
* to be exactly that of course -- this leads to transients in boundary
|
|
* conditions. In specific, the case where the group was idle and we start the
|
|
* one task. It takes time for our CPU's grq->avg.load_avg to build up,
|
|
* yielding bad latency etc..
|
|
*
|
|
* Now, in that special case (1) reduces to:
|
|
*
|
|
* tg->weight * grq->load.weight
|
|
* ge->load.weight = ----------------------------- = tg->weight (4)
|
|
* grp->load.weight
|
|
*
|
|
* That is, the sum collapses because all other CPUs are idle; the UP scenario.
|
|
*
|
|
* So what we do is modify our approximation (3) to approach (4) in the (near)
|
|
* UP case, like:
|
|
*
|
|
* ge->load.weight =
|
|
*
|
|
* tg->weight * grq->load.weight
|
|
* --------------------------------------------------- (5)
|
|
* tg->load_avg - grq->avg.load_avg + grq->load.weight
|
|
*
|
|
* But because grq->load.weight can drop to 0, resulting in a divide by zero,
|
|
* we need to use grq->avg.load_avg as its lower bound, which then gives:
|
|
*
|
|
*
|
|
* tg->weight * grq->load.weight
|
|
* ge->load.weight = ----------------------------- (6)
|
|
* tg_load_avg'
|
|
*
|
|
* Where:
|
|
*
|
|
* tg_load_avg' = tg->load_avg - grq->avg.load_avg +
|
|
* max(grq->load.weight, grq->avg.load_avg)
|
|
*
|
|
* And that is shares_weight and is icky. In the (near) UP case it approaches
|
|
* (4) while in the normal case it approaches (3). It consistently
|
|
* overestimates the ge->load.weight and therefore:
|
|
*
|
|
* \Sum ge->load.weight >= tg->weight
|
|
*
|
|
* hence icky!
|
|
*/
|
|
static long calc_group_shares(struct cfs_rq *cfs_rq)
|
|
{
|
|
long tg_weight, tg_shares, load, shares;
|
|
struct task_group *tg = cfs_rq->tg;
|
|
|
|
tg_shares = READ_ONCE(tg->shares);
|
|
|
|
load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
|
|
|
|
tg_weight = atomic_long_read(&tg->load_avg);
|
|
|
|
/* Ensure tg_weight >= load */
|
|
tg_weight -= cfs_rq->tg_load_avg_contrib;
|
|
tg_weight += load;
|
|
|
|
shares = (tg_shares * load);
|
|
if (tg_weight)
|
|
shares /= tg_weight;
|
|
|
|
/*
|
|
* MIN_SHARES has to be unscaled here to support per-CPU partitioning
|
|
* of a group with small tg->shares value. It is a floor value which is
|
|
* assigned as a minimum load.weight to the sched_entity representing
|
|
* the group on a CPU.
|
|
*
|
|
* E.g. on 64-bit for a group with tg->shares of scale_load(15)=15*1024
|
|
* on an 8-core system with 8 tasks each runnable on one CPU shares has
|
|
* to be 15*1024*1/8=1920 instead of scale_load(MIN_SHARES)=2*1024. In
|
|
* case no task is runnable on a CPU MIN_SHARES=2 should be returned
|
|
* instead of 0.
|
|
*/
|
|
return clamp_t(long, shares, MIN_SHARES, tg_shares);
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* Recomputes the group entity based on the current state of its group
|
|
* runqueue.
|
|
*/
|
|
static void update_cfs_group(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *gcfs_rq = group_cfs_rq(se);
|
|
long shares;
|
|
|
|
if (!gcfs_rq)
|
|
return;
|
|
|
|
if (throttled_hierarchy(gcfs_rq))
|
|
return;
|
|
|
|
#ifndef CONFIG_SMP
|
|
shares = READ_ONCE(gcfs_rq->tg->shares);
|
|
#else
|
|
shares = calc_group_shares(gcfs_rq);
|
|
#endif
|
|
if (unlikely(se->load.weight != shares))
|
|
reweight_entity(cfs_rq_of(se), se, shares);
|
|
}
|
|
|
|
#else /* CONFIG_FAIR_GROUP_SCHED */
|
|
static inline void update_cfs_group(struct sched_entity *se)
|
|
{
|
|
}
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
if (&rq->cfs == cfs_rq) {
|
|
/*
|
|
* There are a few boundary cases this might miss but it should
|
|
* get called often enough that that should (hopefully) not be
|
|
* a real problem.
|
|
*
|
|
* It will not get called when we go idle, because the idle
|
|
* thread is a different class (!fair), nor will the utilization
|
|
* number include things like RT tasks.
|
|
*
|
|
* As is, the util number is not freq-invariant (we'd have to
|
|
* implement arch_scale_freq_capacity() for that).
|
|
*
|
|
* See cpu_util_cfs().
|
|
*/
|
|
cpufreq_update_util(rq, flags);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static inline bool load_avg_is_decayed(struct sched_avg *sa)
|
|
{
|
|
if (sa->load_sum)
|
|
return false;
|
|
|
|
if (sa->util_sum)
|
|
return false;
|
|
|
|
if (sa->runnable_sum)
|
|
return false;
|
|
|
|
/*
|
|
* _avg must be null when _sum are null because _avg = _sum / divider
|
|
* Make sure that rounding and/or propagation of PELT values never
|
|
* break this.
|
|
*/
|
|
SCHED_WARN_ON(sa->load_avg ||
|
|
sa->util_avg ||
|
|
sa->runnable_avg);
|
|
|
|
return true;
|
|
}
|
|
|
|
static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
|
|
{
|
|
return u64_u32_load_copy(cfs_rq->avg.last_update_time,
|
|
cfs_rq->last_update_time_copy);
|
|
}
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
|
|
* immediately before a parent cfs_rq, and cfs_rqs are removed from the list
|
|
* bottom-up, we only have to test whether the cfs_rq before us on the list
|
|
* is our child.
|
|
* If cfs_rq is not on the list, test whether a child needs its to be added to
|
|
* connect a branch to the tree * (see list_add_leaf_cfs_rq() for details).
|
|
*/
|
|
static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct cfs_rq *prev_cfs_rq;
|
|
struct list_head *prev;
|
|
|
|
if (cfs_rq->on_list) {
|
|
prev = cfs_rq->leaf_cfs_rq_list.prev;
|
|
} else {
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
prev = rq->tmp_alone_branch;
|
|
}
|
|
|
|
prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
|
|
|
|
return (prev_cfs_rq->tg->parent == cfs_rq->tg);
|
|
}
|
|
|
|
static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (cfs_rq->load.weight)
|
|
return false;
|
|
|
|
if (!load_avg_is_decayed(&cfs_rq->avg))
|
|
return false;
|
|
|
|
if (child_cfs_rq_on_list(cfs_rq))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* update_tg_load_avg - update the tg's load avg
|
|
* @cfs_rq: the cfs_rq whose avg changed
|
|
*
|
|
* This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load.
|
|
* However, because tg->load_avg is a global value there are performance
|
|
* considerations.
|
|
*
|
|
* In order to avoid having to look at the other cfs_rq's, we use a
|
|
* differential update where we store the last value we propagated. This in
|
|
* turn allows skipping updates if the differential is 'small'.
|
|
*
|
|
* Updating tg's load_avg is necessary before update_cfs_share().
|
|
*/
|
|
static inline void update_tg_load_avg(struct cfs_rq *cfs_rq)
|
|
{
|
|
long delta;
|
|
u64 now;
|
|
|
|
/*
|
|
* No need to update load_avg for root_task_group as it is not used.
|
|
*/
|
|
if (cfs_rq->tg == &root_task_group)
|
|
return;
|
|
|
|
/* rq has been offline and doesn't contribute to the share anymore: */
|
|
if (!cpu_active(cpu_of(rq_of(cfs_rq))))
|
|
return;
|
|
|
|
/*
|
|
* For migration heavy workloads, access to tg->load_avg can be
|
|
* unbound. Limit the update rate to at most once per ms.
|
|
*/
|
|
now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
|
|
if (now - cfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
|
|
return;
|
|
|
|
delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
|
|
if (abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
|
|
atomic_long_add(delta, &cfs_rq->tg->load_avg);
|
|
cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
|
|
cfs_rq->last_update_tg_load_avg = now;
|
|
}
|
|
}
|
|
|
|
static inline void clear_tg_load_avg(struct cfs_rq *cfs_rq)
|
|
{
|
|
long delta;
|
|
u64 now;
|
|
|
|
/*
|
|
* No need to update load_avg for root_task_group, as it is not used.
|
|
*/
|
|
if (cfs_rq->tg == &root_task_group)
|
|
return;
|
|
|
|
now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
|
|
delta = 0 - cfs_rq->tg_load_avg_contrib;
|
|
atomic_long_add(delta, &cfs_rq->tg->load_avg);
|
|
cfs_rq->tg_load_avg_contrib = 0;
|
|
cfs_rq->last_update_tg_load_avg = now;
|
|
}
|
|
|
|
/* CPU offline callback: */
|
|
static void __maybe_unused clear_tg_offline_cfs_rqs(struct rq *rq)
|
|
{
|
|
struct task_group *tg;
|
|
|
|
lockdep_assert_rq_held(rq);
|
|
|
|
/*
|
|
* The rq clock has already been updated in
|
|
* set_rq_offline(), so we should skip updating
|
|
* the rq clock again in unthrottle_cfs_rq().
|
|
*/
|
|
rq_clock_start_loop_update(rq);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(tg, &task_groups, list) {
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
clear_tg_load_avg(cfs_rq);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
rq_clock_stop_loop_update(rq);
|
|
}
|
|
|
|
/*
|
|
* Called within set_task_rq() right before setting a task's CPU. The
|
|
* caller only guarantees p->pi_lock is held; no other assumptions,
|
|
* including the state of rq->lock, should be made.
|
|
*/
|
|
void set_task_rq_fair(struct sched_entity *se,
|
|
struct cfs_rq *prev, struct cfs_rq *next)
|
|
{
|
|
u64 p_last_update_time;
|
|
u64 n_last_update_time;
|
|
|
|
if (!sched_feat(ATTACH_AGE_LOAD))
|
|
return;
|
|
|
|
/*
|
|
* We are supposed to update the task to "current" time, then its up to
|
|
* date and ready to go to new CPU/cfs_rq. But we have difficulty in
|
|
* getting what current time is, so simply throw away the out-of-date
|
|
* time. This will result in the wakee task is less decayed, but giving
|
|
* the wakee more load sounds not bad.
|
|
*/
|
|
if (!(se->avg.last_update_time && prev))
|
|
return;
|
|
|
|
p_last_update_time = cfs_rq_last_update_time(prev);
|
|
n_last_update_time = cfs_rq_last_update_time(next);
|
|
|
|
__update_load_avg_blocked_se(p_last_update_time, se);
|
|
se->avg.last_update_time = n_last_update_time;
|
|
}
|
|
|
|
/*
|
|
* When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
|
|
* propagate its contribution. The key to this propagation is the invariant
|
|
* that for each group:
|
|
*
|
|
* ge->avg == grq->avg (1)
|
|
*
|
|
* _IFF_ we look at the pure running and runnable sums. Because they
|
|
* represent the very same entity, just at different points in the hierarchy.
|
|
*
|
|
* Per the above update_tg_cfs_util() and update_tg_cfs_runnable() are trivial
|
|
* and simply copies the running/runnable sum over (but still wrong, because
|
|
* the group entity and group rq do not have their PELT windows aligned).
|
|
*
|
|
* However, update_tg_cfs_load() is more complex. So we have:
|
|
*
|
|
* ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg (2)
|
|
*
|
|
* And since, like util, the runnable part should be directly transferable,
|
|
* the following would _appear_ to be the straight forward approach:
|
|
*
|
|
* grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg (3)
|
|
*
|
|
* And per (1) we have:
|
|
*
|
|
* ge->avg.runnable_avg == grq->avg.runnable_avg
|
|
*
|
|
* Which gives:
|
|
*
|
|
* ge->load.weight * grq->avg.load_avg
|
|
* ge->avg.load_avg = ----------------------------------- (4)
|
|
* grq->load.weight
|
|
*
|
|
* Except that is wrong!
|
|
*
|
|
* Because while for entities historical weight is not important and we
|
|
* really only care about our future and therefore can consider a pure
|
|
* runnable sum, runqueues can NOT do this.
|
|
*
|
|
* We specifically want runqueues to have a load_avg that includes
|
|
* historical weights. Those represent the blocked load, the load we expect
|
|
* to (shortly) return to us. This only works by keeping the weights as
|
|
* integral part of the sum. We therefore cannot decompose as per (3).
|
|
*
|
|
* Another reason this doesn't work is that runnable isn't a 0-sum entity.
|
|
* Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the
|
|
* rq itself is runnable anywhere between 2/3 and 1 depending on how the
|
|
* runnable section of these tasks overlap (or not). If they were to perfectly
|
|
* align the rq as a whole would be runnable 2/3 of the time. If however we
|
|
* always have at least 1 runnable task, the rq as a whole is always runnable.
|
|
*
|
|
* So we'll have to approximate.. :/
|
|
*
|
|
* Given the constraint:
|
|
*
|
|
* ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX
|
|
*
|
|
* We can construct a rule that adds runnable to a rq by assuming minimal
|
|
* overlap.
|
|
*
|
|
* On removal, we'll assume each task is equally runnable; which yields:
|
|
*
|
|
* grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight
|
|
*
|
|
* XXX: only do this for the part of runnable > running ?
|
|
*
|
|
*/
|
|
static inline void
|
|
update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
|
|
{
|
|
long delta_sum, delta_avg = gcfs_rq->avg.util_avg - se->avg.util_avg;
|
|
u32 new_sum, divider;
|
|
|
|
/* Nothing to update */
|
|
if (!delta_avg)
|
|
return;
|
|
|
|
/*
|
|
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
|
|
* See ___update_load_avg() for details.
|
|
*/
|
|
divider = get_pelt_divider(&cfs_rq->avg);
|
|
|
|
|
|
/* Set new sched_entity's utilization */
|
|
se->avg.util_avg = gcfs_rq->avg.util_avg;
|
|
new_sum = se->avg.util_avg * divider;
|
|
delta_sum = (long)new_sum - (long)se->avg.util_sum;
|
|
se->avg.util_sum = new_sum;
|
|
|
|
/* Update parent cfs_rq utilization */
|
|
add_positive(&cfs_rq->avg.util_avg, delta_avg);
|
|
add_positive(&cfs_rq->avg.util_sum, delta_sum);
|
|
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
|
|
cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
|
|
}
|
|
|
|
static inline void
|
|
update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
|
|
{
|
|
long delta_sum, delta_avg = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
|
|
u32 new_sum, divider;
|
|
|
|
/* Nothing to update */
|
|
if (!delta_avg)
|
|
return;
|
|
|
|
/*
|
|
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
|
|
* See ___update_load_avg() for details.
|
|
*/
|
|
divider = get_pelt_divider(&cfs_rq->avg);
|
|
|
|
/* Set new sched_entity's runnable */
|
|
se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
|
|
new_sum = se->avg.runnable_avg * divider;
|
|
delta_sum = (long)new_sum - (long)se->avg.runnable_sum;
|
|
se->avg.runnable_sum = new_sum;
|
|
|
|
/* Update parent cfs_rq runnable */
|
|
add_positive(&cfs_rq->avg.runnable_avg, delta_avg);
|
|
add_positive(&cfs_rq->avg.runnable_sum, delta_sum);
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
|
|
cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
|
|
}
|
|
|
|
static inline void
|
|
update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
|
|
{
|
|
long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
|
|
unsigned long load_avg;
|
|
u64 load_sum = 0;
|
|
s64 delta_sum;
|
|
u32 divider;
|
|
|
|
if (!runnable_sum)
|
|
return;
|
|
|
|
gcfs_rq->prop_runnable_sum = 0;
|
|
|
|
/*
|
|
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
|
|
* See ___update_load_avg() for details.
|
|
*/
|
|
divider = get_pelt_divider(&cfs_rq->avg);
|
|
|
|
if (runnable_sum >= 0) {
|
|
/*
|
|
* Add runnable; clip at LOAD_AVG_MAX. Reflects that until
|
|
* the CPU is saturated running == runnable.
|
|
*/
|
|
runnable_sum += se->avg.load_sum;
|
|
runnable_sum = min_t(long, runnable_sum, divider);
|
|
} else {
|
|
/*
|
|
* Estimate the new unweighted runnable_sum of the gcfs_rq by
|
|
* assuming all tasks are equally runnable.
|
|
*/
|
|
if (scale_load_down(gcfs_rq->load.weight)) {
|
|
load_sum = div_u64(gcfs_rq->avg.load_sum,
|
|
scale_load_down(gcfs_rq->load.weight));
|
|
}
|
|
|
|
/* But make sure to not inflate se's runnable */
|
|
runnable_sum = min(se->avg.load_sum, load_sum);
|
|
}
|
|
|
|
/*
|
|
* runnable_sum can't be lower than running_sum
|
|
* Rescale running sum to be in the same range as runnable sum
|
|
* running_sum is in [0 : LOAD_AVG_MAX << SCHED_CAPACITY_SHIFT]
|
|
* runnable_sum is in [0 : LOAD_AVG_MAX]
|
|
*/
|
|
running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
|
|
runnable_sum = max(runnable_sum, running_sum);
|
|
|
|
load_sum = se_weight(se) * runnable_sum;
|
|
load_avg = div_u64(load_sum, divider);
|
|
|
|
delta_avg = load_avg - se->avg.load_avg;
|
|
if (!delta_avg)
|
|
return;
|
|
|
|
delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
|
|
|
|
se->avg.load_sum = runnable_sum;
|
|
se->avg.load_avg = load_avg;
|
|
add_positive(&cfs_rq->avg.load_avg, delta_avg);
|
|
add_positive(&cfs_rq->avg.load_sum, delta_sum);
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
|
|
cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
|
|
}
|
|
|
|
static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
|
|
{
|
|
cfs_rq->propagate = 1;
|
|
cfs_rq->prop_runnable_sum += runnable_sum;
|
|
}
|
|
|
|
/* Update task and its cfs_rq load average */
|
|
static inline int propagate_entity_load_avg(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq, *gcfs_rq;
|
|
|
|
if (entity_is_task(se))
|
|
return 0;
|
|
|
|
gcfs_rq = group_cfs_rq(se);
|
|
if (!gcfs_rq->propagate)
|
|
return 0;
|
|
|
|
gcfs_rq->propagate = 0;
|
|
|
|
cfs_rq = cfs_rq_of(se);
|
|
|
|
add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
|
|
|
|
update_tg_cfs_util(cfs_rq, se, gcfs_rq);
|
|
update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
|
|
update_tg_cfs_load(cfs_rq, se, gcfs_rq);
|
|
|
|
trace_pelt_cfs_tp(cfs_rq);
|
|
trace_pelt_se_tp(se);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Check if we need to update the load and the utilization of a blocked
|
|
* group_entity:
|
|
*/
|
|
static inline bool skip_blocked_update(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *gcfs_rq = group_cfs_rq(se);
|
|
|
|
/*
|
|
* If sched_entity still have not zero load or utilization, we have to
|
|
* decay it:
|
|
*/
|
|
if (se->avg.load_avg || se->avg.util_avg)
|
|
return false;
|
|
|
|
/*
|
|
* If there is a pending propagation, we have to update the load and
|
|
* the utilization of the sched_entity:
|
|
*/
|
|
if (gcfs_rq->propagate)
|
|
return false;
|
|
|
|
/*
|
|
* Otherwise, the load and the utilization of the sched_entity is
|
|
* already zero and there is no pending propagation, so it will be a
|
|
* waste of time to try to decay it:
|
|
*/
|
|
return true;
|
|
}
|
|
|
|
#else /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
static inline void update_tg_load_avg(struct cfs_rq *cfs_rq) {}
|
|
|
|
static inline void clear_tg_offline_cfs_rqs(struct rq *rq) {}
|
|
|
|
static inline int propagate_entity_load_avg(struct sched_entity *se)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
|
|
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
static inline void migrate_se_pelt_lag(struct sched_entity *se)
|
|
{
|
|
u64 throttled = 0, now, lut;
|
|
struct cfs_rq *cfs_rq;
|
|
struct rq *rq;
|
|
bool is_idle;
|
|
|
|
if (load_avg_is_decayed(&se->avg))
|
|
return;
|
|
|
|
cfs_rq = cfs_rq_of(se);
|
|
rq = rq_of(cfs_rq);
|
|
|
|
rcu_read_lock();
|
|
is_idle = is_idle_task(rcu_dereference(rq->curr));
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* The lag estimation comes with a cost we don't want to pay all the
|
|
* time. Hence, limiting to the case where the source CPU is idle and
|
|
* we know we are at the greatest risk to have an outdated clock.
|
|
*/
|
|
if (!is_idle)
|
|
return;
|
|
|
|
/*
|
|
* Estimated "now" is: last_update_time + cfs_idle_lag + rq_idle_lag, where:
|
|
*
|
|
* last_update_time (the cfs_rq's last_update_time)
|
|
* = cfs_rq_clock_pelt()@cfs_rq_idle
|
|
* = rq_clock_pelt()@cfs_rq_idle
|
|
* - cfs->throttled_clock_pelt_time@cfs_rq_idle
|
|
*
|
|
* cfs_idle_lag (delta between rq's update and cfs_rq's update)
|
|
* = rq_clock_pelt()@rq_idle - rq_clock_pelt()@cfs_rq_idle
|
|
*
|
|
* rq_idle_lag (delta between now and rq's update)
|
|
* = sched_clock_cpu() - rq_clock()@rq_idle
|
|
*
|
|
* We can then write:
|
|
*
|
|
* now = rq_clock_pelt()@rq_idle - cfs->throttled_clock_pelt_time +
|
|
* sched_clock_cpu() - rq_clock()@rq_idle
|
|
* Where:
|
|
* rq_clock_pelt()@rq_idle is rq->clock_pelt_idle
|
|
* rq_clock()@rq_idle is rq->clock_idle
|
|
* cfs->throttled_clock_pelt_time@cfs_rq_idle
|
|
* is cfs_rq->throttled_pelt_idle
|
|
*/
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
throttled = u64_u32_load(cfs_rq->throttled_pelt_idle);
|
|
/* The clock has been stopped for throttling */
|
|
if (throttled == U64_MAX)
|
|
return;
|
|
#endif
|
|
now = u64_u32_load(rq->clock_pelt_idle);
|
|
/*
|
|
* Paired with _update_idle_rq_clock_pelt(). It ensures at the worst case
|
|
* is observed the old clock_pelt_idle value and the new clock_idle,
|
|
* which lead to an underestimation. The opposite would lead to an
|
|
* overestimation.
|
|
*/
|
|
smp_rmb();
|
|
lut = cfs_rq_last_update_time(cfs_rq);
|
|
|
|
now -= throttled;
|
|
if (now < lut)
|
|
/*
|
|
* cfs_rq->avg.last_update_time is more recent than our
|
|
* estimation, let's use it.
|
|
*/
|
|
now = lut;
|
|
else
|
|
now += sched_clock_cpu(cpu_of(rq)) - u64_u32_load(rq->clock_idle);
|
|
|
|
__update_load_avg_blocked_se(now, se);
|
|
}
|
|
#else
|
|
static void migrate_se_pelt_lag(struct sched_entity *se) {}
|
|
#endif
|
|
|
|
/**
|
|
* update_cfs_rq_load_avg - update the cfs_rq's load/util averages
|
|
* @now: current time, as per cfs_rq_clock_pelt()
|
|
* @cfs_rq: cfs_rq to update
|
|
*
|
|
* The cfs_rq avg is the direct sum of all its entities (blocked and runnable)
|
|
* avg. The immediate corollary is that all (fair) tasks must be attached.
|
|
*
|
|
* cfs_rq->avg is used for task_h_load() and update_cfs_share() for example.
|
|
*
|
|
* Return: true if the load decayed or we removed load.
|
|
*
|
|
* Since both these conditions indicate a changed cfs_rq->avg.load we should
|
|
* call update_tg_load_avg() when this function returns true.
|
|
*/
|
|
static inline int
|
|
update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
|
|
{
|
|
unsigned long removed_load = 0, removed_util = 0, removed_runnable = 0;
|
|
struct sched_avg *sa = &cfs_rq->avg;
|
|
int decayed = 0;
|
|
|
|
if (cfs_rq->removed.nr) {
|
|
unsigned long r;
|
|
u32 divider = get_pelt_divider(&cfs_rq->avg);
|
|
|
|
raw_spin_lock(&cfs_rq->removed.lock);
|
|
swap(cfs_rq->removed.util_avg, removed_util);
|
|
swap(cfs_rq->removed.load_avg, removed_load);
|
|
swap(cfs_rq->removed.runnable_avg, removed_runnable);
|
|
cfs_rq->removed.nr = 0;
|
|
raw_spin_unlock(&cfs_rq->removed.lock);
|
|
|
|
r = removed_load;
|
|
sub_positive(&sa->load_avg, r);
|
|
sub_positive(&sa->load_sum, r * divider);
|
|
/* See sa->util_sum below */
|
|
sa->load_sum = max_t(u32, sa->load_sum, sa->load_avg * PELT_MIN_DIVIDER);
|
|
|
|
r = removed_util;
|
|
sub_positive(&sa->util_avg, r);
|
|
sub_positive(&sa->util_sum, r * divider);
|
|
/*
|
|
* Because of rounding, se->util_sum might ends up being +1 more than
|
|
* cfs->util_sum. Although this is not a problem by itself, detaching
|
|
* a lot of tasks with the rounding problem between 2 updates of
|
|
* util_avg (~1ms) can make cfs->util_sum becoming null whereas
|
|
* cfs_util_avg is not.
|
|
* Check that util_sum is still above its lower bound for the new
|
|
* util_avg. Given that period_contrib might have moved since the last
|
|
* sync, we are only sure that util_sum must be above or equal to
|
|
* util_avg * minimum possible divider
|
|
*/
|
|
sa->util_sum = max_t(u32, sa->util_sum, sa->util_avg * PELT_MIN_DIVIDER);
|
|
|
|
r = removed_runnable;
|
|
sub_positive(&sa->runnable_avg, r);
|
|
sub_positive(&sa->runnable_sum, r * divider);
|
|
/* See sa->util_sum above */
|
|
sa->runnable_sum = max_t(u32, sa->runnable_sum,
|
|
sa->runnable_avg * PELT_MIN_DIVIDER);
|
|
|
|
/*
|
|
* removed_runnable is the unweighted version of removed_load so we
|
|
* can use it to estimate removed_load_sum.
|
|
*/
|
|
add_tg_cfs_propagate(cfs_rq,
|
|
-(long)(removed_runnable * divider) >> SCHED_CAPACITY_SHIFT);
|
|
|
|
decayed = 1;
|
|
}
|
|
|
|
decayed |= __update_load_avg_cfs_rq(now, cfs_rq);
|
|
u64_u32_store_copy(sa->last_update_time,
|
|
cfs_rq->last_update_time_copy,
|
|
sa->last_update_time);
|
|
return decayed;
|
|
}
|
|
|
|
/**
|
|
* attach_entity_load_avg - attach this entity to its cfs_rq load avg
|
|
* @cfs_rq: cfs_rq to attach to
|
|
* @se: sched_entity to attach
|
|
*
|
|
* Must call update_cfs_rq_load_avg() before this, since we rely on
|
|
* cfs_rq->avg.last_update_time being current.
|
|
*/
|
|
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
|
|
* See ___update_load_avg() for details.
|
|
*/
|
|
u32 divider = get_pelt_divider(&cfs_rq->avg);
|
|
|
|
/*
|
|
* When we attach the @se to the @cfs_rq, we must align the decay
|
|
* window because without that, really weird and wonderful things can
|
|
* happen.
|
|
*
|
|
* XXX illustrate
|
|
*/
|
|
se->avg.last_update_time = cfs_rq->avg.last_update_time;
|
|
se->avg.period_contrib = cfs_rq->avg.period_contrib;
|
|
|
|
/*
|
|
* Hell(o) Nasty stuff.. we need to recompute _sum based on the new
|
|
* period_contrib. This isn't strictly correct, but since we're
|
|
* entirely outside of the PELT hierarchy, nobody cares if we truncate
|
|
* _sum a little.
|
|
*/
|
|
se->avg.util_sum = se->avg.util_avg * divider;
|
|
|
|
se->avg.runnable_sum = se->avg.runnable_avg * divider;
|
|
|
|
se->avg.load_sum = se->avg.load_avg * divider;
|
|
if (se_weight(se) < se->avg.load_sum)
|
|
se->avg.load_sum = div_u64(se->avg.load_sum, se_weight(se));
|
|
else
|
|
se->avg.load_sum = 1;
|
|
|
|
enqueue_load_avg(cfs_rq, se);
|
|
cfs_rq->avg.util_avg += se->avg.util_avg;
|
|
cfs_rq->avg.util_sum += se->avg.util_sum;
|
|
cfs_rq->avg.runnable_avg += se->avg.runnable_avg;
|
|
cfs_rq->avg.runnable_sum += se->avg.runnable_sum;
|
|
|
|
add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
|
|
|
|
cfs_rq_util_change(cfs_rq, 0);
|
|
|
|
trace_pelt_cfs_tp(cfs_rq);
|
|
}
|
|
|
|
/**
|
|
* detach_entity_load_avg - detach this entity from its cfs_rq load avg
|
|
* @cfs_rq: cfs_rq to detach from
|
|
* @se: sched_entity to detach
|
|
*
|
|
* Must call update_cfs_rq_load_avg() before this, since we rely on
|
|
* cfs_rq->avg.last_update_time being current.
|
|
*/
|
|
static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
dequeue_load_avg(cfs_rq, se);
|
|
sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
|
|
sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
|
|
cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
|
|
|
|
sub_positive(&cfs_rq->avg.runnable_avg, se->avg.runnable_avg);
|
|
sub_positive(&cfs_rq->avg.runnable_sum, se->avg.runnable_sum);
|
|
/* See update_cfs_rq_load_avg() */
|
|
cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
|
|
cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
|
|
|
|
add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
|
|
|
|
cfs_rq_util_change(cfs_rq, 0);
|
|
|
|
trace_pelt_cfs_tp(cfs_rq);
|
|
}
|
|
|
|
/*
|
|
* Optional action to be done while updating the load average
|
|
*/
|
|
#define UPDATE_TG 0x1
|
|
#define SKIP_AGE_LOAD 0x2
|
|
#define DO_ATTACH 0x4
|
|
#define DO_DETACH 0x8
|
|
|
|
/* Update task and its cfs_rq load average */
|
|
static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
u64 now = cfs_rq_clock_pelt(cfs_rq);
|
|
int decayed;
|
|
|
|
/*
|
|
* Track task load average for carrying it to new CPU after migrated, and
|
|
* track group sched_entity load average for task_h_load calc in migration
|
|
*/
|
|
if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
|
|
__update_load_avg_se(now, cfs_rq, se);
|
|
|
|
decayed = update_cfs_rq_load_avg(now, cfs_rq);
|
|
decayed |= propagate_entity_load_avg(se);
|
|
|
|
if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
|
|
|
|
/*
|
|
* DO_ATTACH means we're here from enqueue_entity().
|
|
* !last_update_time means we've passed through
|
|
* migrate_task_rq_fair() indicating we migrated.
|
|
*
|
|
* IOW we're enqueueing a task on a new CPU.
|
|
*/
|
|
attach_entity_load_avg(cfs_rq, se);
|
|
update_tg_load_avg(cfs_rq);
|
|
|
|
} else if (flags & DO_DETACH) {
|
|
/*
|
|
* DO_DETACH means we're here from dequeue_entity()
|
|
* and we are migrating task out of the CPU.
|
|
*/
|
|
detach_entity_load_avg(cfs_rq, se);
|
|
update_tg_load_avg(cfs_rq);
|
|
} else if (decayed) {
|
|
cfs_rq_util_change(cfs_rq, 0);
|
|
|
|
if (flags & UPDATE_TG)
|
|
update_tg_load_avg(cfs_rq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Synchronize entity load avg of dequeued entity without locking
|
|
* the previous rq.
|
|
*/
|
|
static void sync_entity_load_avg(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
u64 last_update_time;
|
|
|
|
last_update_time = cfs_rq_last_update_time(cfs_rq);
|
|
__update_load_avg_blocked_se(last_update_time, se);
|
|
}
|
|
|
|
/*
|
|
* Task first catches up with cfs_rq, and then subtract
|
|
* itself from the cfs_rq (task must be off the queue now).
|
|
*/
|
|
static void remove_entity_load_avg(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* tasks cannot exit without having gone through wake_up_new_task() ->
|
|
* enqueue_task_fair() which will have added things to the cfs_rq,
|
|
* so we can remove unconditionally.
|
|
*/
|
|
|
|
sync_entity_load_avg(se);
|
|
|
|
raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
|
|
++cfs_rq->removed.nr;
|
|
cfs_rq->removed.util_avg += se->avg.util_avg;
|
|
cfs_rq->removed.load_avg += se->avg.load_avg;
|
|
cfs_rq->removed.runnable_avg += se->avg.runnable_avg;
|
|
raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
|
|
}
|
|
|
|
static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_rq->avg.runnable_avg;
|
|
}
|
|
|
|
static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_rq->avg.load_avg;
|
|
}
|
|
|
|
static int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
|
|
|
|
static inline unsigned long task_util(struct task_struct *p)
|
|
{
|
|
return READ_ONCE(p->se.avg.util_avg);
|
|
}
|
|
|
|
static inline unsigned long task_runnable(struct task_struct *p)
|
|
{
|
|
return READ_ONCE(p->se.avg.runnable_avg);
|
|
}
|
|
|
|
static inline unsigned long _task_util_est(struct task_struct *p)
|
|
{
|
|
return READ_ONCE(p->se.avg.util_est) & ~UTIL_AVG_UNCHANGED;
|
|
}
|
|
|
|
static inline unsigned long task_util_est(struct task_struct *p)
|
|
{
|
|
return max(task_util(p), _task_util_est(p));
|
|
}
|
|
|
|
static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
|
|
struct task_struct *p)
|
|
{
|
|
unsigned int enqueued;
|
|
|
|
if (!sched_feat(UTIL_EST))
|
|
return;
|
|
|
|
/* Update root cfs_rq's estimated utilization */
|
|
enqueued = cfs_rq->avg.util_est;
|
|
enqueued += _task_util_est(p);
|
|
WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
|
|
|
|
trace_sched_util_est_cfs_tp(cfs_rq);
|
|
}
|
|
|
|
static inline void util_est_dequeue(struct cfs_rq *cfs_rq,
|
|
struct task_struct *p)
|
|
{
|
|
unsigned int enqueued;
|
|
|
|
if (!sched_feat(UTIL_EST))
|
|
return;
|
|
|
|
/* Update root cfs_rq's estimated utilization */
|
|
enqueued = cfs_rq->avg.util_est;
|
|
enqueued -= min_t(unsigned int, enqueued, _task_util_est(p));
|
|
WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
|
|
|
|
trace_sched_util_est_cfs_tp(cfs_rq);
|
|
}
|
|
|
|
#define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
|
|
|
|
static inline void util_est_update(struct cfs_rq *cfs_rq,
|
|
struct task_struct *p,
|
|
bool task_sleep)
|
|
{
|
|
unsigned int ewma, dequeued, last_ewma_diff;
|
|
|
|
if (!sched_feat(UTIL_EST))
|
|
return;
|
|
|
|
/*
|
|
* Skip update of task's estimated utilization when the task has not
|
|
* yet completed an activation, e.g. being migrated.
|
|
*/
|
|
if (!task_sleep)
|
|
return;
|
|
|
|
/* Get current estimate of utilization */
|
|
ewma = READ_ONCE(p->se.avg.util_est);
|
|
|
|
/*
|
|
* If the PELT values haven't changed since enqueue time,
|
|
* skip the util_est update.
|
|
*/
|
|
if (ewma & UTIL_AVG_UNCHANGED)
|
|
return;
|
|
|
|
/* Get utilization at dequeue */
|
|
dequeued = task_util(p);
|
|
|
|
/*
|
|
* Reset EWMA on utilization increases, the moving average is used only
|
|
* to smooth utilization decreases.
|
|
*/
|
|
if (ewma <= dequeued) {
|
|
ewma = dequeued;
|
|
goto done;
|
|
}
|
|
|
|
/*
|
|
* Skip update of task's estimated utilization when its members are
|
|
* already ~1% close to its last activation value.
|
|
*/
|
|
last_ewma_diff = ewma - dequeued;
|
|
if (last_ewma_diff < UTIL_EST_MARGIN)
|
|
goto done;
|
|
|
|
/*
|
|
* To avoid overestimation of actual task utilization, skip updates if
|
|
* we cannot grant there is idle time in this CPU.
|
|
*/
|
|
if (dequeued > arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq))))
|
|
return;
|
|
|
|
/*
|
|
* To avoid underestimate of task utilization, skip updates of EWMA if
|
|
* we cannot grant that thread got all CPU time it wanted.
|
|
*/
|
|
if ((dequeued + UTIL_EST_MARGIN) < task_runnable(p))
|
|
goto done;
|
|
|
|
|
|
/*
|
|
* Update Task's estimated utilization
|
|
*
|
|
* When *p completes an activation we can consolidate another sample
|
|
* of the task size. This is done by using this value to update the
|
|
* Exponential Weighted Moving Average (EWMA):
|
|
*
|
|
* ewma(t) = w * task_util(p) + (1-w) * ewma(t-1)
|
|
* = w * task_util(p) + ewma(t-1) - w * ewma(t-1)
|
|
* = w * (task_util(p) - ewma(t-1)) + ewma(t-1)
|
|
* = w * ( -last_ewma_diff ) + ewma(t-1)
|
|
* = w * (-last_ewma_diff + ewma(t-1) / w)
|
|
*
|
|
* Where 'w' is the weight of new samples, which is configured to be
|
|
* 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
|
|
*/
|
|
ewma <<= UTIL_EST_WEIGHT_SHIFT;
|
|
ewma -= last_ewma_diff;
|
|
ewma >>= UTIL_EST_WEIGHT_SHIFT;
|
|
done:
|
|
ewma |= UTIL_AVG_UNCHANGED;
|
|
WRITE_ONCE(p->se.avg.util_est, ewma);
|
|
|
|
trace_sched_util_est_se_tp(&p->se);
|
|
}
|
|
|
|
static inline int util_fits_cpu(unsigned long util,
|
|
unsigned long uclamp_min,
|
|
unsigned long uclamp_max,
|
|
int cpu)
|
|
{
|
|
unsigned long capacity_orig, capacity_orig_thermal;
|
|
unsigned long capacity = capacity_of(cpu);
|
|
bool fits, uclamp_max_fits;
|
|
|
|
/*
|
|
* Check if the real util fits without any uclamp boost/cap applied.
|
|
*/
|
|
fits = fits_capacity(util, capacity);
|
|
|
|
if (!uclamp_is_used())
|
|
return fits;
|
|
|
|
/*
|
|
* We must use arch_scale_cpu_capacity() for comparing against uclamp_min and
|
|
* uclamp_max. We only care about capacity pressure (by using
|
|
* capacity_of()) for comparing against the real util.
|
|
*
|
|
* If a task is boosted to 1024 for example, we don't want a tiny
|
|
* pressure to skew the check whether it fits a CPU or not.
|
|
*
|
|
* Similarly if a task is capped to arch_scale_cpu_capacity(little_cpu), it
|
|
* should fit a little cpu even if there's some pressure.
|
|
*
|
|
* Only exception is for thermal pressure since it has a direct impact
|
|
* on available OPP of the system.
|
|
*
|
|
* We honour it for uclamp_min only as a drop in performance level
|
|
* could result in not getting the requested minimum performance level.
|
|
*
|
|
* For uclamp_max, we can tolerate a drop in performance level as the
|
|
* goal is to cap the task. So it's okay if it's getting less.
|
|
*/
|
|
capacity_orig = arch_scale_cpu_capacity(cpu);
|
|
capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu);
|
|
|
|
/*
|
|
* We want to force a task to fit a cpu as implied by uclamp_max.
|
|
* But we do have some corner cases to cater for..
|
|
*
|
|
*
|
|
* C=z
|
|
* | ___
|
|
* | C=y | |
|
|
* |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
|
|
* | C=x | | | |
|
|
* | ___ | | | |
|
|
* | | | | | | | (util somewhere in this region)
|
|
* | | | | | | |
|
|
* | | | | | | |
|
|
* +----------------------------------------
|
|
* cpu0 cpu1 cpu2
|
|
*
|
|
* In the above example if a task is capped to a specific performance
|
|
* point, y, then when:
|
|
*
|
|
* * util = 80% of x then it does not fit on cpu0 and should migrate
|
|
* to cpu1
|
|
* * util = 80% of y then it is forced to fit on cpu1 to honour
|
|
* uclamp_max request.
|
|
*
|
|
* which is what we're enforcing here. A task always fits if
|
|
* uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
|
|
* the normal upmigration rules should withhold still.
|
|
*
|
|
* Only exception is when we are on max capacity, then we need to be
|
|
* careful not to block overutilized state. This is so because:
|
|
*
|
|
* 1. There's no concept of capping at max_capacity! We can't go
|
|
* beyond this performance level anyway.
|
|
* 2. The system is being saturated when we're operating near
|
|
* max capacity, it doesn't make sense to block overutilized.
|
|
*/
|
|
uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
|
|
uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
|
|
fits = fits || uclamp_max_fits;
|
|
|
|
/*
|
|
*
|
|
* C=z
|
|
* | ___ (region a, capped, util >= uclamp_max)
|
|
* | C=y | |
|
|
* |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
|
|
* | C=x | | | |
|
|
* | ___ | | | | (region b, uclamp_min <= util <= uclamp_max)
|
|
* |_ _ _|_ _|_ _ _ _| _ | _ _ _| _ | _ _ _ _ _ uclamp_min
|
|
* | | | | | | |
|
|
* | | | | | | | (region c, boosted, util < uclamp_min)
|
|
* +----------------------------------------
|
|
* cpu0 cpu1 cpu2
|
|
*
|
|
* a) If util > uclamp_max, then we're capped, we don't care about
|
|
* actual fitness value here. We only care if uclamp_max fits
|
|
* capacity without taking margin/pressure into account.
|
|
* See comment above.
|
|
*
|
|
* b) If uclamp_min <= util <= uclamp_max, then the normal
|
|
* fits_capacity() rules apply. Except we need to ensure that we
|
|
* enforce we remain within uclamp_max, see comment above.
|
|
*
|
|
* c) If util < uclamp_min, then we are boosted. Same as (b) but we
|
|
* need to take into account the boosted value fits the CPU without
|
|
* taking margin/pressure into account.
|
|
*
|
|
* Cases (a) and (b) are handled in the 'fits' variable already. We
|
|
* just need to consider an extra check for case (c) after ensuring we
|
|
* handle the case uclamp_min > uclamp_max.
|
|
*/
|
|
uclamp_min = min(uclamp_min, uclamp_max);
|
|
if (fits && (util < uclamp_min) && (uclamp_min > capacity_orig_thermal))
|
|
return -1;
|
|
|
|
return fits;
|
|
}
|
|
|
|
static inline int task_fits_cpu(struct task_struct *p, int cpu)
|
|
{
|
|
unsigned long uclamp_min = uclamp_eff_value(p, UCLAMP_MIN);
|
|
unsigned long uclamp_max = uclamp_eff_value(p, UCLAMP_MAX);
|
|
unsigned long util = task_util_est(p);
|
|
/*
|
|
* Return true only if the cpu fully fits the task requirements, which
|
|
* include the utilization but also the performance hints.
|
|
*/
|
|
return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0);
|
|
}
|
|
|
|
static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
|
|
{
|
|
if (!sched_asym_cpucap_active())
|
|
return;
|
|
|
|
if (!p || p->nr_cpus_allowed == 1) {
|
|
rq->misfit_task_load = 0;
|
|
return;
|
|
}
|
|
|
|
if (task_fits_cpu(p, cpu_of(rq))) {
|
|
rq->misfit_task_load = 0;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Make sure that misfit_task_load will not be null even if
|
|
* task_h_load() returns 0.
|
|
*/
|
|
rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
|
|
}
|
|
|
|
#else /* CONFIG_SMP */
|
|
|
|
static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
|
|
{
|
|
return !cfs_rq->nr_running;
|
|
}
|
|
|
|
#define UPDATE_TG 0x0
|
|
#define SKIP_AGE_LOAD 0x0
|
|
#define DO_ATTACH 0x0
|
|
#define DO_DETACH 0x0
|
|
|
|
static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
|
|
{
|
|
cfs_rq_util_change(cfs_rq, 0);
|
|
}
|
|
|
|
static inline void remove_entity_load_avg(struct sched_entity *se) {}
|
|
|
|
static inline void
|
|
attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
|
|
static inline void
|
|
detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
|
|
|
|
static inline int newidle_balance(struct rq *rq, struct rq_flags *rf)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void
|
|
util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
|
|
|
|
static inline void
|
|
util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
|
|
|
|
static inline void
|
|
util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p,
|
|
bool task_sleep) {}
|
|
static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void
|
|
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
u64 vslice, vruntime = avg_vruntime(cfs_rq);
|
|
s64 lag = 0;
|
|
|
|
se->slice = sysctl_sched_base_slice;
|
|
vslice = calc_delta_fair(se->slice, se);
|
|
|
|
/*
|
|
* Due to how V is constructed as the weighted average of entities,
|
|
* adding tasks with positive lag, or removing tasks with negative lag
|
|
* will move 'time' backwards, this can screw around with the lag of
|
|
* other tasks.
|
|
*
|
|
* EEVDF: placement strategy #1 / #2
|
|
*/
|
|
if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
unsigned long load;
|
|
|
|
lag = se->vlag;
|
|
|
|
/*
|
|
* If we want to place a task and preserve lag, we have to
|
|
* consider the effect of the new entity on the weighted
|
|
* average and compensate for this, otherwise lag can quickly
|
|
* evaporate.
|
|
*
|
|
* Lag is defined as:
|
|
*
|
|
* lag_i = S - s_i = w_i * (V - v_i)
|
|
*
|
|
* To avoid the 'w_i' term all over the place, we only track
|
|
* the virtual lag:
|
|
*
|
|
* vl_i = V - v_i <=> v_i = V - vl_i
|
|
*
|
|
* And we take V to be the weighted average of all v:
|
|
*
|
|
* V = (\Sum w_j*v_j) / W
|
|
*
|
|
* Where W is: \Sum w_j
|
|
*
|
|
* Then, the weighted average after adding an entity with lag
|
|
* vl_i is given by:
|
|
*
|
|
* V' = (\Sum w_j*v_j + w_i*v_i) / (W + w_i)
|
|
* = (W*V + w_i*(V - vl_i)) / (W + w_i)
|
|
* = (W*V + w_i*V - w_i*vl_i) / (W + w_i)
|
|
* = (V*(W + w_i) - w_i*l) / (W + w_i)
|
|
* = V - w_i*vl_i / (W + w_i)
|
|
*
|
|
* And the actual lag after adding an entity with vl_i is:
|
|
*
|
|
* vl'_i = V' - v_i
|
|
* = V - w_i*vl_i / (W + w_i) - (V - vl_i)
|
|
* = vl_i - w_i*vl_i / (W + w_i)
|
|
*
|
|
* Which is strictly less than vl_i. So in order to preserve lag
|
|
* we should inflate the lag before placement such that the
|
|
* effective lag after placement comes out right.
|
|
*
|
|
* As such, invert the above relation for vl'_i to get the vl_i
|
|
* we need to use such that the lag after placement is the lag
|
|
* we computed before dequeue.
|
|
*
|
|
* vl'_i = vl_i - w_i*vl_i / (W + w_i)
|
|
* = ((W + w_i)*vl_i - w_i*vl_i) / (W + w_i)
|
|
*
|
|
* (W + w_i)*vl'_i = (W + w_i)*vl_i - w_i*vl_i
|
|
* = W*vl_i
|
|
*
|
|
* vl_i = (W + w_i)*vl'_i / W
|
|
*/
|
|
load = cfs_rq->avg_load;
|
|
if (curr && curr->on_rq)
|
|
load += scale_load_down(curr->load.weight);
|
|
|
|
lag *= load + scale_load_down(se->load.weight);
|
|
if (WARN_ON_ONCE(!load))
|
|
load = 1;
|
|
lag = div_s64(lag, load);
|
|
}
|
|
|
|
se->vruntime = vruntime - lag;
|
|
|
|
/*
|
|
* When joining the competition; the exisiting tasks will be,
|
|
* on average, halfway through their slice, as such start tasks
|
|
* off with half a slice to ease into the competition.
|
|
*/
|
|
if (sched_feat(PLACE_DEADLINE_INITIAL) && (flags & ENQUEUE_INITIAL))
|
|
vslice /= 2;
|
|
|
|
/*
|
|
* EEVDF: vd_i = ve_i + r_i/w_i
|
|
*/
|
|
se->deadline = se->vruntime + vslice;
|
|
}
|
|
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
|
|
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);
|
|
|
|
static inline bool cfs_bandwidth_used(void);
|
|
|
|
static void
|
|
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
bool curr = cfs_rq->curr == se;
|
|
|
|
/*
|
|
* If we're the current task, we must renormalise before calling
|
|
* update_curr().
|
|
*/
|
|
if (curr)
|
|
place_entity(cfs_rq, se, flags);
|
|
|
|
update_curr(cfs_rq);
|
|
|
|
/*
|
|
* When enqueuing a sched_entity, we must:
|
|
* - Update loads to have both entity and cfs_rq synced with now.
|
|
* - For group_entity, update its runnable_weight to reflect the new
|
|
* h_nr_running of its group cfs_rq.
|
|
* - For group_entity, update its weight to reflect the new share of
|
|
* its group cfs_rq
|
|
* - Add its new weight to cfs_rq->load.weight
|
|
*/
|
|
update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
|
|
se_update_runnable(se);
|
|
/*
|
|
* XXX update_load_avg() above will have attached us to the pelt sum;
|
|
* but update_cfs_group() here will re-adjust the weight and have to
|
|
* undo/redo all that. Seems wasteful.
|
|
*/
|
|
update_cfs_group(se);
|
|
|
|
/*
|
|
* XXX now that the entity has been re-weighted, and it's lag adjusted,
|
|
* we can place the entity.
|
|
*/
|
|
if (!curr)
|
|
place_entity(cfs_rq, se, flags);
|
|
|
|
account_entity_enqueue(cfs_rq, se);
|
|
|
|
/* Entity has migrated, no longer consider this task hot */
|
|
if (flags & ENQUEUE_MIGRATED)
|
|
se->exec_start = 0;
|
|
|
|
check_schedstat_required();
|
|
update_stats_enqueue_fair(cfs_rq, se, flags);
|
|
if (!curr)
|
|
__enqueue_entity(cfs_rq, se);
|
|
se->on_rq = 1;
|
|
|
|
if (cfs_rq->nr_running == 1) {
|
|
check_enqueue_throttle(cfs_rq);
|
|
if (!throttled_hierarchy(cfs_rq)) {
|
|
list_add_leaf_cfs_rq(cfs_rq);
|
|
} else {
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
if (cfs_rq_throttled(cfs_rq) && !cfs_rq->throttled_clock)
|
|
cfs_rq->throttled_clock = rq_clock(rq);
|
|
if (!cfs_rq->throttled_clock_self)
|
|
cfs_rq->throttled_clock_self = rq_clock(rq);
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
|
|
static void __clear_buddies_next(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
if (cfs_rq->next != se)
|
|
break;
|
|
|
|
cfs_rq->next = NULL;
|
|
}
|
|
}
|
|
|
|
static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
if (cfs_rq->next == se)
|
|
__clear_buddies_next(se);
|
|
}
|
|
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
|
|
|
|
static void
|
|
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
int action = UPDATE_TG;
|
|
|
|
if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
|
|
action |= DO_DETACH;
|
|
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
/*
|
|
* When dequeuing a sched_entity, we must:
|
|
* - Update loads to have both entity and cfs_rq synced with now.
|
|
* - For group_entity, update its runnable_weight to reflect the new
|
|
* h_nr_running of its group cfs_rq.
|
|
* - Subtract its previous weight from cfs_rq->load.weight.
|
|
* - For group entity, update its weight to reflect the new share
|
|
* of its group cfs_rq.
|
|
*/
|
|
update_load_avg(cfs_rq, se, action);
|
|
se_update_runnable(se);
|
|
|
|
update_stats_dequeue_fair(cfs_rq, se, flags);
|
|
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
update_entity_lag(cfs_rq, se);
|
|
if (se != cfs_rq->curr)
|
|
__dequeue_entity(cfs_rq, se);
|
|
se->on_rq = 0;
|
|
account_entity_dequeue(cfs_rq, se);
|
|
|
|
/* return excess runtime on last dequeue */
|
|
return_cfs_rq_runtime(cfs_rq);
|
|
|
|
update_cfs_group(se);
|
|
|
|
/*
|
|
* Now advance min_vruntime if @se was the entity holding it back,
|
|
* except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
|
|
* put back on, and if we advance min_vruntime, we'll be placed back
|
|
* further than we started -- ie. we'll be penalized.
|
|
*/
|
|
if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
|
|
update_min_vruntime(cfs_rq);
|
|
|
|
if (cfs_rq->nr_running == 0)
|
|
update_idle_cfs_rq_clock_pelt(cfs_rq);
|
|
}
|
|
|
|
static void
|
|
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
/* 'current' is not kept within the tree. */
|
|
if (se->on_rq) {
|
|
/*
|
|
* Any task has to be enqueued before it get to execute on
|
|
* a CPU. So account for the time it spent waiting on the
|
|
* runqueue.
|
|
*/
|
|
update_stats_wait_end_fair(cfs_rq, se);
|
|
__dequeue_entity(cfs_rq, se);
|
|
update_load_avg(cfs_rq, se, UPDATE_TG);
|
|
/*
|
|
* HACK, stash a copy of deadline at the point of pick in vlag,
|
|
* which isn't used until dequeue.
|
|
*/
|
|
se->vlag = se->deadline;
|
|
}
|
|
|
|
update_stats_curr_start(cfs_rq, se);
|
|
cfs_rq->curr = se;
|
|
|
|
/*
|
|
* Track our maximum slice length, if the CPU's load is at
|
|
* least twice that of our own weight (i.e. dont track it
|
|
* when there are only lesser-weight tasks around):
|
|
*/
|
|
if (schedstat_enabled() &&
|
|
rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
|
|
struct sched_statistics *stats;
|
|
|
|
stats = __schedstats_from_se(se);
|
|
__schedstat_set(stats->slice_max,
|
|
max((u64)stats->slice_max,
|
|
se->sum_exec_runtime - se->prev_sum_exec_runtime));
|
|
}
|
|
|
|
se->prev_sum_exec_runtime = se->sum_exec_runtime;
|
|
}
|
|
|
|
/*
|
|
* Pick the next process, keeping these things in mind, in this order:
|
|
* 1) keep things fair between processes/task groups
|
|
* 2) pick the "next" process, since someone really wants that to run
|
|
* 3) pick the "last" process, for cache locality
|
|
* 4) do not run the "skip" process, if something else is available
|
|
*/
|
|
static struct sched_entity *
|
|
pick_next_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
/*
|
|
* Enabling NEXT_BUDDY will affect latency but not fairness.
|
|
*/
|
|
if (sched_feat(NEXT_BUDDY) &&
|
|
cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next))
|
|
return cfs_rq->next;
|
|
|
|
return pick_eevdf(cfs_rq);
|
|
}
|
|
|
|
static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
|
|
|
|
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
|
|
{
|
|
/*
|
|
* If still on the runqueue then deactivate_task()
|
|
* was not called and update_curr() has to be done:
|
|
*/
|
|
if (prev->on_rq)
|
|
update_curr(cfs_rq);
|
|
|
|
/* throttle cfs_rqs exceeding runtime */
|
|
check_cfs_rq_runtime(cfs_rq);
|
|
|
|
if (prev->on_rq) {
|
|
update_stats_wait_start_fair(cfs_rq, prev);
|
|
/* Put 'current' back into the tree. */
|
|
__enqueue_entity(cfs_rq, prev);
|
|
/* in !on_rq case, update occurred at dequeue */
|
|
update_load_avg(cfs_rq, prev, 0);
|
|
}
|
|
cfs_rq->curr = NULL;
|
|
}
|
|
|
|
static void
|
|
entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
/*
|
|
* Ensure that runnable average is periodically updated.
|
|
*/
|
|
update_load_avg(cfs_rq, curr, UPDATE_TG);
|
|
update_cfs_group(curr);
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
/*
|
|
* queued ticks are scheduled to match the slice, so don't bother
|
|
* validating it and just reschedule.
|
|
*/
|
|
if (queued) {
|
|
resched_curr(rq_of(cfs_rq));
|
|
return;
|
|
}
|
|
/*
|
|
* don't let the period tick interfere with the hrtick preemption
|
|
*/
|
|
if (!sched_feat(DOUBLE_TICK) &&
|
|
hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
|
|
return;
|
|
#endif
|
|
}
|
|
|
|
|
|
/**************************************************
|
|
* CFS bandwidth control machinery
|
|
*/
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
|
|
#ifdef CONFIG_JUMP_LABEL
|
|
static struct static_key __cfs_bandwidth_used;
|
|
|
|
static inline bool cfs_bandwidth_used(void)
|
|
{
|
|
return static_key_false(&__cfs_bandwidth_used);
|
|
}
|
|
|
|
void cfs_bandwidth_usage_inc(void)
|
|
{
|
|
static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
|
|
}
|
|
|
|
void cfs_bandwidth_usage_dec(void)
|
|
{
|
|
static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
|
|
}
|
|
#else /* CONFIG_JUMP_LABEL */
|
|
static bool cfs_bandwidth_used(void)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
void cfs_bandwidth_usage_inc(void) {}
|
|
void cfs_bandwidth_usage_dec(void) {}
|
|
#endif /* CONFIG_JUMP_LABEL */
|
|
|
|
/*
|
|
* default period for cfs group bandwidth.
|
|
* default: 0.1s, units: nanoseconds
|
|
*/
|
|
static inline u64 default_cfs_period(void)
|
|
{
|
|
return 100000000ULL;
|
|
}
|
|
|
|
static inline u64 sched_cfs_bandwidth_slice(void)
|
|
{
|
|
return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
|
|
}
|
|
|
|
/*
|
|
* Replenish runtime according to assigned quota. We use sched_clock_cpu
|
|
* directly instead of rq->clock to avoid adding additional synchronization
|
|
* around rq->lock.
|
|
*
|
|
* requires cfs_b->lock
|
|
*/
|
|
void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
s64 runtime;
|
|
|
|
if (unlikely(cfs_b->quota == RUNTIME_INF))
|
|
return;
|
|
|
|
cfs_b->runtime += cfs_b->quota;
|
|
runtime = cfs_b->runtime_snap - cfs_b->runtime;
|
|
if (runtime > 0) {
|
|
cfs_b->burst_time += runtime;
|
|
cfs_b->nr_burst++;
|
|
}
|
|
|
|
cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
|
|
cfs_b->runtime_snap = cfs_b->runtime;
|
|
}
|
|
|
|
static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
|
|
{
|
|
return &tg->cfs_bandwidth;
|
|
}
|
|
|
|
/* returns 0 on failure to allocate runtime */
|
|
static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
|
|
struct cfs_rq *cfs_rq, u64 target_runtime)
|
|
{
|
|
u64 min_amount, amount = 0;
|
|
|
|
lockdep_assert_held(&cfs_b->lock);
|
|
|
|
/* note: this is a positive sum as runtime_remaining <= 0 */
|
|
min_amount = target_runtime - cfs_rq->runtime_remaining;
|
|
|
|
if (cfs_b->quota == RUNTIME_INF)
|
|
amount = min_amount;
|
|
else {
|
|
start_cfs_bandwidth(cfs_b);
|
|
|
|
if (cfs_b->runtime > 0) {
|
|
amount = min(cfs_b->runtime, min_amount);
|
|
cfs_b->runtime -= amount;
|
|
cfs_b->idle = 0;
|
|
}
|
|
}
|
|
|
|
cfs_rq->runtime_remaining += amount;
|
|
|
|
return cfs_rq->runtime_remaining > 0;
|
|
}
|
|
|
|
/* returns 0 on failure to allocate runtime */
|
|
static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
int ret;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
|
|
{
|
|
/* dock delta_exec before expiring quota (as it could span periods) */
|
|
cfs_rq->runtime_remaining -= delta_exec;
|
|
|
|
if (likely(cfs_rq->runtime_remaining > 0))
|
|
return;
|
|
|
|
if (cfs_rq->throttled)
|
|
return;
|
|
/*
|
|
* if we're unable to extend our runtime we resched so that the active
|
|
* hierarchy can be throttled
|
|
*/
|
|
if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
|
|
resched_curr(rq_of(cfs_rq));
|
|
}
|
|
|
|
static __always_inline
|
|
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
|
|
{
|
|
if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
|
|
return;
|
|
|
|
__account_cfs_rq_runtime(cfs_rq, delta_exec);
|
|
}
|
|
|
|
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_bandwidth_used() && cfs_rq->throttled;
|
|
}
|
|
|
|
/* check whether cfs_rq, or any parent, is throttled */
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_bandwidth_used() && cfs_rq->throttle_count;
|
|
}
|
|
|
|
/*
|
|
* Ensure that neither of the group entities corresponding to src_cpu or
|
|
* dest_cpu are members of a throttled hierarchy when performing group
|
|
* load-balance operations.
|
|
*/
|
|
static inline int throttled_lb_pair(struct task_group *tg,
|
|
int src_cpu, int dest_cpu)
|
|
{
|
|
struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
|
|
|
|
src_cfs_rq = tg->cfs_rq[src_cpu];
|
|
dest_cfs_rq = tg->cfs_rq[dest_cpu];
|
|
|
|
return throttled_hierarchy(src_cfs_rq) ||
|
|
throttled_hierarchy(dest_cfs_rq);
|
|
}
|
|
|
|
static int tg_unthrottle_up(struct task_group *tg, void *data)
|
|
{
|
|
struct rq *rq = data;
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
cfs_rq->throttle_count--;
|
|
if (!cfs_rq->throttle_count) {
|
|
cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
|
|
cfs_rq->throttled_clock_pelt;
|
|
|
|
/* Add cfs_rq with load or one or more already running entities to the list */
|
|
if (!cfs_rq_is_decayed(cfs_rq))
|
|
list_add_leaf_cfs_rq(cfs_rq);
|
|
|
|
if (cfs_rq->throttled_clock_self) {
|
|
u64 delta = rq_clock(rq) - cfs_rq->throttled_clock_self;
|
|
|
|
cfs_rq->throttled_clock_self = 0;
|
|
|
|
if (SCHED_WARN_ON((s64)delta < 0))
|
|
delta = 0;
|
|
|
|
cfs_rq->throttled_clock_self_time += delta;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tg_throttle_down(struct task_group *tg, void *data)
|
|
{
|
|
struct rq *rq = data;
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
/* group is entering throttled state, stop time */
|
|
if (!cfs_rq->throttle_count) {
|
|
cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
|
|
list_del_leaf_cfs_rq(cfs_rq);
|
|
|
|
SCHED_WARN_ON(cfs_rq->throttled_clock_self);
|
|
if (cfs_rq->nr_running)
|
|
cfs_rq->throttled_clock_self = rq_clock(rq);
|
|
}
|
|
cfs_rq->throttle_count++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
struct sched_entity *se;
|
|
long task_delta, idle_task_delta, dequeue = 1;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
/* This will start the period timer if necessary */
|
|
if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
|
|
/*
|
|
* We have raced with bandwidth becoming available, and if we
|
|
* actually throttled the timer might not unthrottle us for an
|
|
* entire period. We additionally needed to make sure that any
|
|
* subsequent check_cfs_rq_runtime calls agree not to throttle
|
|
* us, as we may commit to do cfs put_prev+pick_next, so we ask
|
|
* for 1ns of runtime rather than just check cfs_b.
|
|
*/
|
|
dequeue = 0;
|
|
} else {
|
|
list_add_tail_rcu(&cfs_rq->throttled_list,
|
|
&cfs_b->throttled_cfs_rq);
|
|
}
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
if (!dequeue)
|
|
return false; /* Throttle no longer required. */
|
|
|
|
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
|
|
|
|
/* freeze hierarchy runnable averages while throttled */
|
|
rcu_read_lock();
|
|
walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
|
|
rcu_read_unlock();
|
|
|
|
task_delta = cfs_rq->h_nr_running;
|
|
idle_task_delta = cfs_rq->idle_h_nr_running;
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
|
|
/* throttled entity or throttle-on-deactivate */
|
|
if (!se->on_rq)
|
|
goto done;
|
|
|
|
dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
|
|
|
|
if (cfs_rq_is_idle(group_cfs_rq(se)))
|
|
idle_task_delta = cfs_rq->h_nr_running;
|
|
|
|
qcfs_rq->h_nr_running -= task_delta;
|
|
qcfs_rq->idle_h_nr_running -= idle_task_delta;
|
|
|
|
if (qcfs_rq->load.weight) {
|
|
/* Avoid re-evaluating load for this entity: */
|
|
se = parent_entity(se);
|
|
break;
|
|
}
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
|
|
/* throttled entity or throttle-on-deactivate */
|
|
if (!se->on_rq)
|
|
goto done;
|
|
|
|
update_load_avg(qcfs_rq, se, 0);
|
|
se_update_runnable(se);
|
|
|
|
if (cfs_rq_is_idle(group_cfs_rq(se)))
|
|
idle_task_delta = cfs_rq->h_nr_running;
|
|
|
|
qcfs_rq->h_nr_running -= task_delta;
|
|
qcfs_rq->idle_h_nr_running -= idle_task_delta;
|
|
}
|
|
|
|
/* At this point se is NULL and we are at root level*/
|
|
sub_nr_running(rq, task_delta);
|
|
|
|
done:
|
|
/*
|
|
* Note: distribution will already see us throttled via the
|
|
* throttled-list. rq->lock protects completion.
|
|
*/
|
|
cfs_rq->throttled = 1;
|
|
SCHED_WARN_ON(cfs_rq->throttled_clock);
|
|
if (cfs_rq->nr_running)
|
|
cfs_rq->throttled_clock = rq_clock(rq);
|
|
return true;
|
|
}
|
|
|
|
void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
struct sched_entity *se;
|
|
long task_delta, idle_task_delta;
|
|
|
|
se = cfs_rq->tg->se[cpu_of(rq)];
|
|
|
|
cfs_rq->throttled = 0;
|
|
|
|
update_rq_clock(rq);
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (cfs_rq->throttled_clock) {
|
|
cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
|
|
cfs_rq->throttled_clock = 0;
|
|
}
|
|
list_del_rcu(&cfs_rq->throttled_list);
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
/* update hierarchical throttle state */
|
|
walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
|
|
|
|
if (!cfs_rq->load.weight) {
|
|
if (!cfs_rq->on_list)
|
|
return;
|
|
/*
|
|
* Nothing to run but something to decay (on_list)?
|
|
* Complete the branch.
|
|
*/
|
|
for_each_sched_entity(se) {
|
|
if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
|
|
break;
|
|
}
|
|
goto unthrottle_throttle;
|
|
}
|
|
|
|
task_delta = cfs_rq->h_nr_running;
|
|
idle_task_delta = cfs_rq->idle_h_nr_running;
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
|
|
|
|
if (se->on_rq)
|
|
break;
|
|
enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
|
|
|
|
if (cfs_rq_is_idle(group_cfs_rq(se)))
|
|
idle_task_delta = cfs_rq->h_nr_running;
|
|
|
|
qcfs_rq->h_nr_running += task_delta;
|
|
qcfs_rq->idle_h_nr_running += idle_task_delta;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(qcfs_rq))
|
|
goto unthrottle_throttle;
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
|
|
|
|
update_load_avg(qcfs_rq, se, UPDATE_TG);
|
|
se_update_runnable(se);
|
|
|
|
if (cfs_rq_is_idle(group_cfs_rq(se)))
|
|
idle_task_delta = cfs_rq->h_nr_running;
|
|
|
|
qcfs_rq->h_nr_running += task_delta;
|
|
qcfs_rq->idle_h_nr_running += idle_task_delta;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(qcfs_rq))
|
|
goto unthrottle_throttle;
|
|
}
|
|
|
|
/* At this point se is NULL and we are at root level*/
|
|
add_nr_running(rq, task_delta);
|
|
|
|
unthrottle_throttle:
|
|
assert_list_leaf_cfs_rq(rq);
|
|
|
|
/* Determine whether we need to wake up potentially idle CPU: */
|
|
if (rq->curr == rq->idle && rq->cfs.nr_running)
|
|
resched_curr(rq);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static void __cfsb_csd_unthrottle(void *arg)
|
|
{
|
|
struct cfs_rq *cursor, *tmp;
|
|
struct rq *rq = arg;
|
|
struct rq_flags rf;
|
|
|
|
rq_lock(rq, &rf);
|
|
|
|
/*
|
|
* Iterating over the list can trigger several call to
|
|
* update_rq_clock() in unthrottle_cfs_rq().
|
|
* Do it once and skip the potential next ones.
|
|
*/
|
|
update_rq_clock(rq);
|
|
rq_clock_start_loop_update(rq);
|
|
|
|
/*
|
|
* Since we hold rq lock we're safe from concurrent manipulation of
|
|
* the CSD list. However, this RCU critical section annotates the
|
|
* fact that we pair with sched_free_group_rcu(), so that we cannot
|
|
* race with group being freed in the window between removing it
|
|
* from the list and advancing to the next entry in the list.
|
|
*/
|
|
rcu_read_lock();
|
|
|
|
list_for_each_entry_safe(cursor, tmp, &rq->cfsb_csd_list,
|
|
throttled_csd_list) {
|
|
list_del_init(&cursor->throttled_csd_list);
|
|
|
|
if (cfs_rq_throttled(cursor))
|
|
unthrottle_cfs_rq(cursor);
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
|
|
rq_clock_stop_loop_update(rq);
|
|
rq_unlock(rq, &rf);
|
|
}
|
|
|
|
static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
bool first;
|
|
|
|
if (rq == this_rq()) {
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
return;
|
|
}
|
|
|
|
/* Already enqueued */
|
|
if (SCHED_WARN_ON(!list_empty(&cfs_rq->throttled_csd_list)))
|
|
return;
|
|
|
|
first = list_empty(&rq->cfsb_csd_list);
|
|
list_add_tail(&cfs_rq->throttled_csd_list, &rq->cfsb_csd_list);
|
|
if (first)
|
|
smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
|
|
}
|
|
#else
|
|
static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
|
|
{
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
}
|
|
#endif
|
|
|
|
static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
|
|
{
|
|
lockdep_assert_rq_held(rq_of(cfs_rq));
|
|
|
|
if (SCHED_WARN_ON(!cfs_rq_throttled(cfs_rq) ||
|
|
cfs_rq->runtime_remaining <= 0))
|
|
return;
|
|
|
|
__unthrottle_cfs_rq_async(cfs_rq);
|
|
}
|
|
|
|
static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
int this_cpu = smp_processor_id();
|
|
u64 runtime, remaining = 1;
|
|
bool throttled = false;
|
|
struct cfs_rq *cfs_rq, *tmp;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
LIST_HEAD(local_unthrottle);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
|
|
throttled_list) {
|
|
rq = rq_of(cfs_rq);
|
|
|
|
if (!remaining) {
|
|
throttled = true;
|
|
break;
|
|
}
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
if (!cfs_rq_throttled(cfs_rq))
|
|
goto next;
|
|
|
|
/* Already queued for async unthrottle */
|
|
if (!list_empty(&cfs_rq->throttled_csd_list))
|
|
goto next;
|
|
|
|
/* By the above checks, this should never be true */
|
|
SCHED_WARN_ON(cfs_rq->runtime_remaining > 0);
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
runtime = -cfs_rq->runtime_remaining + 1;
|
|
if (runtime > cfs_b->runtime)
|
|
runtime = cfs_b->runtime;
|
|
cfs_b->runtime -= runtime;
|
|
remaining = cfs_b->runtime;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
cfs_rq->runtime_remaining += runtime;
|
|
|
|
/* we check whether we're throttled above */
|
|
if (cfs_rq->runtime_remaining > 0) {
|
|
if (cpu_of(rq) != this_cpu) {
|
|
unthrottle_cfs_rq_async(cfs_rq);
|
|
} else {
|
|
/*
|
|
* We currently only expect to be unthrottling
|
|
* a single cfs_rq locally.
|
|
*/
|
|
SCHED_WARN_ON(!list_empty(&local_unthrottle));
|
|
list_add_tail(&cfs_rq->throttled_csd_list,
|
|
&local_unthrottle);
|
|
}
|
|
} else {
|
|
throttled = true;
|
|
}
|
|
|
|
next:
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
list_for_each_entry_safe(cfs_rq, tmp, &local_unthrottle,
|
|
throttled_csd_list) {
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
|
|
list_del_init(&cfs_rq->throttled_csd_list);
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
SCHED_WARN_ON(!list_empty(&local_unthrottle));
|
|
|
|
rcu_read_unlock();
|
|
|
|
return throttled;
|
|
}
|
|
|
|
/*
|
|
* Responsible for refilling a task_group's bandwidth and unthrottling its
|
|
* cfs_rqs as appropriate. If there has been no activity within the last
|
|
* period the timer is deactivated until scheduling resumes; cfs_b->idle is
|
|
* used to track this state.
|
|
*/
|
|
static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
|
|
{
|
|
int throttled;
|
|
|
|
/* no need to continue the timer with no bandwidth constraint */
|
|
if (cfs_b->quota == RUNTIME_INF)
|
|
goto out_deactivate;
|
|
|
|
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
|
|
cfs_b->nr_periods += overrun;
|
|
|
|
/* Refill extra burst quota even if cfs_b->idle */
|
|
__refill_cfs_bandwidth_runtime(cfs_b);
|
|
|
|
/*
|
|
* idle depends on !throttled (for the case of a large deficit), and if
|
|
* we're going inactive then everything else can be deferred
|
|
*/
|
|
if (cfs_b->idle && !throttled)
|
|
goto out_deactivate;
|
|
|
|
if (!throttled) {
|
|
/* mark as potentially idle for the upcoming period */
|
|
cfs_b->idle = 1;
|
|
return 0;
|
|
}
|
|
|
|
/* account preceding periods in which throttling occurred */
|
|
cfs_b->nr_throttled += overrun;
|
|
|
|
/*
|
|
* This check is repeated as we release cfs_b->lock while we unthrottle.
|
|
*/
|
|
while (throttled && cfs_b->runtime > 0) {
|
|
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
|
|
/* we can't nest cfs_b->lock while distributing bandwidth */
|
|
throttled = distribute_cfs_runtime(cfs_b);
|
|
raw_spin_lock_irqsave(&cfs_b->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* While we are ensured activity in the period following an
|
|
* unthrottle, this also covers the case in which the new bandwidth is
|
|
* insufficient to cover the existing bandwidth deficit. (Forcing the
|
|
* timer to remain active while there are any throttled entities.)
|
|
*/
|
|
cfs_b->idle = 0;
|
|
|
|
return 0;
|
|
|
|
out_deactivate:
|
|
return 1;
|
|
}
|
|
|
|
/* a cfs_rq won't donate quota below this amount */
|
|
static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
|
|
/* minimum remaining period time to redistribute slack quota */
|
|
static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
|
|
/* how long we wait to gather additional slack before distributing */
|
|
static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
|
|
|
|
/*
|
|
* Are we near the end of the current quota period?
|
|
*
|
|
* Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
|
|
* hrtimer base being cleared by hrtimer_start. In the case of
|
|
* migrate_hrtimers, base is never cleared, so we are fine.
|
|
*/
|
|
static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
|
|
{
|
|
struct hrtimer *refresh_timer = &cfs_b->period_timer;
|
|
s64 remaining;
|
|
|
|
/* if the call-back is running a quota refresh is already occurring */
|
|
if (hrtimer_callback_running(refresh_timer))
|
|
return 1;
|
|
|
|
/* is a quota refresh about to occur? */
|
|
remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
|
|
if (remaining < (s64)min_expire)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
|
|
|
|
/* if there's a quota refresh soon don't bother with slack */
|
|
if (runtime_refresh_within(cfs_b, min_left))
|
|
return;
|
|
|
|
/* don't push forwards an existing deferred unthrottle */
|
|
if (cfs_b->slack_started)
|
|
return;
|
|
cfs_b->slack_started = true;
|
|
|
|
hrtimer_start(&cfs_b->slack_timer,
|
|
ns_to_ktime(cfs_bandwidth_slack_period),
|
|
HRTIMER_MODE_REL);
|
|
}
|
|
|
|
/* we know any runtime found here is valid as update_curr() precedes return */
|
|
static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
|
|
|
|
if (slack_runtime <= 0)
|
|
return;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (cfs_b->quota != RUNTIME_INF) {
|
|
cfs_b->runtime += slack_runtime;
|
|
|
|
/* we are under rq->lock, defer unthrottling using a timer */
|
|
if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
|
|
!list_empty(&cfs_b->throttled_cfs_rq))
|
|
start_cfs_slack_bandwidth(cfs_b);
|
|
}
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
/* even if it's not valid for return we don't want to try again */
|
|
cfs_rq->runtime_remaining -= slack_runtime;
|
|
}
|
|
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
|
|
return;
|
|
|
|
__return_cfs_rq_runtime(cfs_rq);
|
|
}
|
|
|
|
/*
|
|
* This is done with a timer (instead of inline with bandwidth return) since
|
|
* it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
|
|
*/
|
|
static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
|
|
unsigned long flags;
|
|
|
|
/* confirm we're still not at a refresh boundary */
|
|
raw_spin_lock_irqsave(&cfs_b->lock, flags);
|
|
cfs_b->slack_started = false;
|
|
|
|
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
|
|
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
|
|
return;
|
|
}
|
|
|
|
if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
|
|
runtime = cfs_b->runtime;
|
|
|
|
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
|
|
|
|
if (!runtime)
|
|
return;
|
|
|
|
distribute_cfs_runtime(cfs_b);
|
|
}
|
|
|
|
/*
|
|
* When a group wakes up we want to make sure that its quota is not already
|
|
* expired/exceeded, otherwise it may be allowed to steal additional ticks of
|
|
* runtime as update_curr() throttling can not trigger until it's on-rq.
|
|
*/
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
/* an active group must be handled by the update_curr()->put() path */
|
|
if (!cfs_rq->runtime_enabled || cfs_rq->curr)
|
|
return;
|
|
|
|
/* ensure the group is not already throttled */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
return;
|
|
|
|
/* update runtime allocation */
|
|
account_cfs_rq_runtime(cfs_rq, 0);
|
|
if (cfs_rq->runtime_remaining <= 0)
|
|
throttle_cfs_rq(cfs_rq);
|
|
}
|
|
|
|
static void sync_throttle(struct task_group *tg, int cpu)
|
|
{
|
|
struct cfs_rq *pcfs_rq, *cfs_rq;
|
|
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
if (!tg->parent)
|
|
return;
|
|
|
|
cfs_rq = tg->cfs_rq[cpu];
|
|
pcfs_rq = tg->parent->cfs_rq[cpu];
|
|
|
|
cfs_rq->throttle_count = pcfs_rq->throttle_count;
|
|
cfs_rq->throttled_clock_pelt = rq_clock_pelt(cpu_rq(cpu));
|
|
}
|
|
|
|
/* conditionally throttle active cfs_rq's from put_prev_entity() */
|
|
static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return false;
|
|
|
|
if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
|
|
return false;
|
|
|
|
/*
|
|
* it's possible for a throttled entity to be forced into a running
|
|
* state (e.g. set_curr_task), in this case we're finished.
|
|
*/
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
return true;
|
|
|
|
return throttle_cfs_rq(cfs_rq);
|
|
}
|
|
|
|
static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
|
|
{
|
|
struct cfs_bandwidth *cfs_b =
|
|
container_of(timer, struct cfs_bandwidth, slack_timer);
|
|
|
|
do_sched_cfs_slack_timer(cfs_b);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
extern const u64 max_cfs_quota_period;
|
|
|
|
static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
|
|
{
|
|
struct cfs_bandwidth *cfs_b =
|
|
container_of(timer, struct cfs_bandwidth, period_timer);
|
|
unsigned long flags;
|
|
int overrun;
|
|
int idle = 0;
|
|
int count = 0;
|
|
|
|
raw_spin_lock_irqsave(&cfs_b->lock, flags);
|
|
for (;;) {
|
|
overrun = hrtimer_forward_now(timer, cfs_b->period);
|
|
if (!overrun)
|
|
break;
|
|
|
|
idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
|
|
|
|
if (++count > 3) {
|
|
u64 new, old = ktime_to_ns(cfs_b->period);
|
|
|
|
/*
|
|
* Grow period by a factor of 2 to avoid losing precision.
|
|
* Precision loss in the quota/period ratio can cause __cfs_schedulable
|
|
* to fail.
|
|
*/
|
|
new = old * 2;
|
|
if (new < max_cfs_quota_period) {
|
|
cfs_b->period = ns_to_ktime(new);
|
|
cfs_b->quota *= 2;
|
|
cfs_b->burst *= 2;
|
|
|
|
pr_warn_ratelimited(
|
|
"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",
|
|
smp_processor_id(),
|
|
div_u64(new, NSEC_PER_USEC),
|
|
div_u64(cfs_b->quota, NSEC_PER_USEC));
|
|
} else {
|
|
pr_warn_ratelimited(
|
|
"cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",
|
|
smp_processor_id(),
|
|
div_u64(old, NSEC_PER_USEC),
|
|
div_u64(cfs_b->quota, NSEC_PER_USEC));
|
|
}
|
|
|
|
/* reset count so we don't come right back in here */
|
|
count = 0;
|
|
}
|
|
}
|
|
if (idle)
|
|
cfs_b->period_active = 0;
|
|
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
|
|
|
|
return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
|
|
}
|
|
|
|
void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent)
|
|
{
|
|
raw_spin_lock_init(&cfs_b->lock);
|
|
cfs_b->runtime = 0;
|
|
cfs_b->quota = RUNTIME_INF;
|
|
cfs_b->period = ns_to_ktime(default_cfs_period());
|
|
cfs_b->burst = 0;
|
|
cfs_b->hierarchical_quota = parent ? parent->hierarchical_quota : RUNTIME_INF;
|
|
|
|
INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
|
|
hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
|
|
cfs_b->period_timer.function = sched_cfs_period_timer;
|
|
|
|
/* Add a random offset so that timers interleave */
|
|
hrtimer_set_expires(&cfs_b->period_timer,
|
|
get_random_u32_below(cfs_b->period));
|
|
hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
cfs_b->slack_timer.function = sched_cfs_slack_timer;
|
|
cfs_b->slack_started = false;
|
|
}
|
|
|
|
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
cfs_rq->runtime_enabled = 0;
|
|
INIT_LIST_HEAD(&cfs_rq->throttled_list);
|
|
INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
|
|
}
|
|
|
|
void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
lockdep_assert_held(&cfs_b->lock);
|
|
|
|
if (cfs_b->period_active)
|
|
return;
|
|
|
|
cfs_b->period_active = 1;
|
|
hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period);
|
|
hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED);
|
|
}
|
|
|
|
static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
int __maybe_unused i;
|
|
|
|
/* init_cfs_bandwidth() was not called */
|
|
if (!cfs_b->throttled_cfs_rq.next)
|
|
return;
|
|
|
|
hrtimer_cancel(&cfs_b->period_timer);
|
|
hrtimer_cancel(&cfs_b->slack_timer);
|
|
|
|
/*
|
|
* It is possible that we still have some cfs_rq's pending on a CSD
|
|
* list, though this race is very rare. In order for this to occur, we
|
|
* must have raced with the last task leaving the group while there
|
|
* exist throttled cfs_rq(s), and the period_timer must have queued the
|
|
* CSD item but the remote cpu has not yet processed it. To handle this,
|
|
* we can simply flush all pending CSD work inline here. We're
|
|
* guaranteed at this point that no additional cfs_rq of this group can
|
|
* join a CSD list.
|
|
*/
|
|
#ifdef CONFIG_SMP
|
|
for_each_possible_cpu(i) {
|
|
struct rq *rq = cpu_rq(i);
|
|
unsigned long flags;
|
|
|
|
if (list_empty(&rq->cfsb_csd_list))
|
|
continue;
|
|
|
|
local_irq_save(flags);
|
|
__cfsb_csd_unthrottle(rq);
|
|
local_irq_restore(flags);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Both these CPU hotplug callbacks race against unregister_fair_sched_group()
|
|
*
|
|
* The race is harmless, since modifying bandwidth settings of unhooked group
|
|
* bits doesn't do much.
|
|
*/
|
|
|
|
/* cpu online callback */
|
|
static void __maybe_unused update_runtime_enabled(struct rq *rq)
|
|
{
|
|
struct task_group *tg;
|
|
|
|
lockdep_assert_rq_held(rq);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(tg, &task_groups, list) {
|
|
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/* cpu offline callback */
|
|
static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
|
|
{
|
|
struct task_group *tg;
|
|
|
|
lockdep_assert_rq_held(rq);
|
|
|
|
/*
|
|
* The rq clock has already been updated in the
|
|
* set_rq_offline(), so we should skip updating
|
|
* the rq clock again in unthrottle_cfs_rq().
|
|
*/
|
|
rq_clock_start_loop_update(rq);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(tg, &task_groups, list) {
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
if (!cfs_rq->runtime_enabled)
|
|
continue;
|
|
|
|
/*
|
|
* clock_task is not advancing so we just need to make sure
|
|
* there's some valid quota amount
|
|
*/
|
|
cfs_rq->runtime_remaining = 1;
|
|
/*
|
|
* Offline rq is schedulable till CPU is completely disabled
|
|
* in take_cpu_down(), so we prevent new cfs throttling here.
|
|
*/
|
|
cfs_rq->runtime_enabled = 0;
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
rq_clock_stop_loop_update(rq);
|
|
}
|
|
|
|
bool cfs_task_bw_constrained(struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
|
|
if (!cfs_bandwidth_used())
|
|
return false;
|
|
|
|
if (cfs_rq->runtime_enabled ||
|
|
tg_cfs_bandwidth(cfs_rq->tg)->hierarchical_quota != RUNTIME_INF)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_FULL
|
|
/* called from pick_next_task_fair() */
|
|
static void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p)
|
|
{
|
|
int cpu = cpu_of(rq);
|
|
|
|
if (!sched_feat(HZ_BW) || !cfs_bandwidth_used())
|
|
return;
|
|
|
|
if (!tick_nohz_full_cpu(cpu))
|
|
return;
|
|
|
|
if (rq->nr_running != 1)
|
|
return;
|
|
|
|
/*
|
|
* We know there is only one task runnable and we've just picked it. The
|
|
* normal enqueue path will have cleared TICK_DEP_BIT_SCHED if we will
|
|
* be otherwise able to stop the tick. Just need to check if we are using
|
|
* bandwidth control.
|
|
*/
|
|
if (cfs_task_bw_constrained(p))
|
|
tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED);
|
|
}
|
|
#endif
|
|
|
|
#else /* CONFIG_CFS_BANDWIDTH */
|
|
|
|
static inline bool cfs_bandwidth_used(void)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
|
|
static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
|
|
static inline void sync_throttle(struct task_group *tg, int cpu) {}
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
|
|
|
|
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int throttled_lb_pair(struct task_group *tg,
|
|
int src_cpu, int dest_cpu)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
|
|
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
|
|
#endif
|
|
|
|
static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
|
|
{
|
|
return NULL;
|
|
}
|
|
static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
|
|
static inline void update_runtime_enabled(struct rq *rq) {}
|
|
static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
|
|
#ifdef CONFIG_CGROUP_SCHED
|
|
bool cfs_task_bw_constrained(struct task_struct *p)
|
|
{
|
|
return false;
|
|
}
|
|
#endif
|
|
#endif /* CONFIG_CFS_BANDWIDTH */
|
|
|
|
#if !defined(CONFIG_CFS_BANDWIDTH) || !defined(CONFIG_NO_HZ_FULL)
|
|
static inline void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p) {}
|
|
#endif
|
|
|
|
/**************************************************
|
|
* CFS operations on tasks:
|
|
*/
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
SCHED_WARN_ON(task_rq(p) != rq);
|
|
|
|
if (rq->cfs.h_nr_running > 1) {
|
|
u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
|
|
u64 slice = se->slice;
|
|
s64 delta = slice - ran;
|
|
|
|
if (delta < 0) {
|
|
if (task_current(rq, p))
|
|
resched_curr(rq);
|
|
return;
|
|
}
|
|
hrtick_start(rq, delta);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* called from enqueue/dequeue and updates the hrtick when the
|
|
* current task is from our class and nr_running is low enough
|
|
* to matter.
|
|
*/
|
|
static void hrtick_update(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
|
|
if (!hrtick_enabled_fair(rq) || curr->sched_class != &fair_sched_class)
|
|
return;
|
|
|
|
hrtick_start_fair(rq, curr);
|
|
}
|
|
#else /* !CONFIG_SCHED_HRTICK */
|
|
static inline void
|
|
hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline void hrtick_update(struct rq *rq)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
static inline bool cpu_overutilized(int cpu)
|
|
{
|
|
unsigned long rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
|
|
unsigned long rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
|
|
|
|
/* Return true only if the utilization doesn't fit CPU's capacity */
|
|
return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu);
|
|
}
|
|
|
|
static inline void update_overutilized_status(struct rq *rq)
|
|
{
|
|
if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) {
|
|
WRITE_ONCE(rq->rd->overutilized, SG_OVERUTILIZED);
|
|
trace_sched_overutilized_tp(rq->rd, SG_OVERUTILIZED);
|
|
}
|
|
}
|
|
#else
|
|
static inline void update_overutilized_status(struct rq *rq) { }
|
|
#endif
|
|
|
|
/* Runqueue only has SCHED_IDLE tasks enqueued */
|
|
static int sched_idle_rq(struct rq *rq)
|
|
{
|
|
return unlikely(rq->nr_running == rq->cfs.idle_h_nr_running &&
|
|
rq->nr_running);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static int sched_idle_cpu(int cpu)
|
|
{
|
|
return sched_idle_rq(cpu_rq(cpu));
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* The enqueue_task method is called before nr_running is
|
|
* increased. Here we update the fair scheduling stats and
|
|
* then put the task into the rbtree:
|
|
*/
|
|
static void
|
|
enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
int idle_h_nr_running = task_has_idle_policy(p);
|
|
int task_new = !(flags & ENQUEUE_WAKEUP);
|
|
|
|
/*
|
|
* The code below (indirectly) updates schedutil which looks at
|
|
* the cfs_rq utilization to select a frequency.
|
|
* Let's add the task's estimated utilization to the cfs_rq's
|
|
* estimated utilization, before we update schedutil.
|
|
*/
|
|
util_est_enqueue(&rq->cfs, p);
|
|
|
|
/*
|
|
* If in_iowait is set, the code below may not trigger any cpufreq
|
|
* utilization updates, so do it here explicitly with the IOWAIT flag
|
|
* passed.
|
|
*/
|
|
if (p->in_iowait)
|
|
cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
|
|
|
|
for_each_sched_entity(se) {
|
|
if (se->on_rq)
|
|
break;
|
|
cfs_rq = cfs_rq_of(se);
|
|
enqueue_entity(cfs_rq, se, flags);
|
|
|
|
cfs_rq->h_nr_running++;
|
|
cfs_rq->idle_h_nr_running += idle_h_nr_running;
|
|
|
|
if (cfs_rq_is_idle(cfs_rq))
|
|
idle_h_nr_running = 1;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
goto enqueue_throttle;
|
|
|
|
flags = ENQUEUE_WAKEUP;
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
|
|
update_load_avg(cfs_rq, se, UPDATE_TG);
|
|
se_update_runnable(se);
|
|
update_cfs_group(se);
|
|
|
|
cfs_rq->h_nr_running++;
|
|
cfs_rq->idle_h_nr_running += idle_h_nr_running;
|
|
|
|
if (cfs_rq_is_idle(cfs_rq))
|
|
idle_h_nr_running = 1;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
goto enqueue_throttle;
|
|
}
|
|
|
|
/* At this point se is NULL and we are at root level*/
|
|
add_nr_running(rq, 1);
|
|
|
|
/*
|
|
* Since new tasks are assigned an initial util_avg equal to
|
|
* half of the spare capacity of their CPU, tiny tasks have the
|
|
* ability to cross the overutilized threshold, which will
|
|
* result in the load balancer ruining all the task placement
|
|
* done by EAS. As a way to mitigate that effect, do not account
|
|
* for the first enqueue operation of new tasks during the
|
|
* overutilized flag detection.
|
|
*
|
|
* A better way of solving this problem would be to wait for
|
|
* the PELT signals of tasks to converge before taking them
|
|
* into account, but that is not straightforward to implement,
|
|
* and the following generally works well enough in practice.
|
|
*/
|
|
if (!task_new)
|
|
update_overutilized_status(rq);
|
|
|
|
enqueue_throttle:
|
|
assert_list_leaf_cfs_rq(rq);
|
|
|
|
hrtick_update(rq);
|
|
}
|
|
|
|
static void set_next_buddy(struct sched_entity *se);
|
|
|
|
/*
|
|
* The dequeue_task method is called before nr_running is
|
|
* decreased. We remove the task from the rbtree and
|
|
* update the fair scheduling stats:
|
|
*/
|
|
static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
int task_sleep = flags & DEQUEUE_SLEEP;
|
|
int idle_h_nr_running = task_has_idle_policy(p);
|
|
bool was_sched_idle = sched_idle_rq(rq);
|
|
|
|
util_est_dequeue(&rq->cfs, p);
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
dequeue_entity(cfs_rq, se, flags);
|
|
|
|
cfs_rq->h_nr_running--;
|
|
cfs_rq->idle_h_nr_running -= idle_h_nr_running;
|
|
|
|
if (cfs_rq_is_idle(cfs_rq))
|
|
idle_h_nr_running = 1;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
goto dequeue_throttle;
|
|
|
|
/* Don't dequeue parent if it has other entities besides us */
|
|
if (cfs_rq->load.weight) {
|
|
/* Avoid re-evaluating load for this entity: */
|
|
se = parent_entity(se);
|
|
/*
|
|
* Bias pick_next to pick a task from this cfs_rq, as
|
|
* p is sleeping when it is within its sched_slice.
|
|
*/
|
|
if (task_sleep && se && !throttled_hierarchy(cfs_rq))
|
|
set_next_buddy(se);
|
|
break;
|
|
}
|
|
flags |= DEQUEUE_SLEEP;
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
|
|
update_load_avg(cfs_rq, se, UPDATE_TG);
|
|
se_update_runnable(se);
|
|
update_cfs_group(se);
|
|
|
|
cfs_rq->h_nr_running--;
|
|
cfs_rq->idle_h_nr_running -= idle_h_nr_running;
|
|
|
|
if (cfs_rq_is_idle(cfs_rq))
|
|
idle_h_nr_running = 1;
|
|
|
|
/* end evaluation on encountering a throttled cfs_rq */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
goto dequeue_throttle;
|
|
|
|
}
|
|
|
|
/* At this point se is NULL and we are at root level*/
|
|
sub_nr_running(rq, 1);
|
|
|
|
/* balance early to pull high priority tasks */
|
|
if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
|
|
rq->next_balance = jiffies;
|
|
|
|
dequeue_throttle:
|
|
util_est_update(&rq->cfs, p, task_sleep);
|
|
hrtick_update(rq);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/* Working cpumask for: load_balance, load_balance_newidle. */
|
|
static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
|
|
static DEFINE_PER_CPU(cpumask_var_t, select_rq_mask);
|
|
static DEFINE_PER_CPU(cpumask_var_t, should_we_balance_tmpmask);
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
|
|
static struct {
|
|
cpumask_var_t idle_cpus_mask;
|
|
atomic_t nr_cpus;
|
|
int has_blocked; /* Idle CPUS has blocked load */
|
|
int needs_update; /* Newly idle CPUs need their next_balance collated */
|
|
unsigned long next_balance; /* in jiffy units */
|
|
unsigned long next_blocked; /* Next update of blocked load in jiffies */
|
|
} nohz ____cacheline_aligned;
|
|
|
|
#endif /* CONFIG_NO_HZ_COMMON */
|
|
|
|
static unsigned long cpu_load(struct rq *rq)
|
|
{
|
|
return cfs_rq_load_avg(&rq->cfs);
|
|
}
|
|
|
|
/*
|
|
* cpu_load_without - compute CPU load without any contributions from *p
|
|
* @cpu: the CPU which load is requested
|
|
* @p: the task which load should be discounted
|
|
*
|
|
* The load of a CPU is defined by the load of tasks currently enqueued on that
|
|
* CPU as well as tasks which are currently sleeping after an execution on that
|
|
* CPU.
|
|
*
|
|
* This method returns the load of the specified CPU by discounting the load of
|
|
* the specified task, whenever the task is currently contributing to the CPU
|
|
* load.
|
|
*/
|
|
static unsigned long cpu_load_without(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
unsigned int load;
|
|
|
|
/* Task has no contribution or is new */
|
|
if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
|
|
return cpu_load(rq);
|
|
|
|
cfs_rq = &rq->cfs;
|
|
load = READ_ONCE(cfs_rq->avg.load_avg);
|
|
|
|
/* Discount task's util from CPU's util */
|
|
lsub_positive(&load, task_h_load(p));
|
|
|
|
return load;
|
|
}
|
|
|
|
static unsigned long cpu_runnable(struct rq *rq)
|
|
{
|
|
return cfs_rq_runnable_avg(&rq->cfs);
|
|
}
|
|
|
|
static unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
unsigned int runnable;
|
|
|
|
/* Task has no contribution or is new */
|
|
if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
|
|
return cpu_runnable(rq);
|
|
|
|
cfs_rq = &rq->cfs;
|
|
runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
|
|
|
|
/* Discount task's runnable from CPU's runnable */
|
|
lsub_positive(&runnable, p->se.avg.runnable_avg);
|
|
|
|
return runnable;
|
|
}
|
|
|
|
static unsigned long capacity_of(int cpu)
|
|
{
|
|
return cpu_rq(cpu)->cpu_capacity;
|
|
}
|
|
|
|
static void record_wakee(struct task_struct *p)
|
|
{
|
|
/*
|
|
* Only decay a single time; tasks that have less then 1 wakeup per
|
|
* jiffy will not have built up many flips.
|
|
*/
|
|
if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
|
|
current->wakee_flips >>= 1;
|
|
current->wakee_flip_decay_ts = jiffies;
|
|
}
|
|
|
|
if (current->last_wakee != p) {
|
|
current->last_wakee = p;
|
|
current->wakee_flips++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Detect M:N waker/wakee relationships via a switching-frequency heuristic.
|
|
*
|
|
* A waker of many should wake a different task than the one last awakened
|
|
* at a frequency roughly N times higher than one of its wakees.
|
|
*
|
|
* In order to determine whether we should let the load spread vs consolidating
|
|
* to shared cache, we look for a minimum 'flip' frequency of llc_size in one
|
|
* partner, and a factor of lls_size higher frequency in the other.
|
|
*
|
|
* With both conditions met, we can be relatively sure that the relationship is
|
|
* non-monogamous, with partner count exceeding socket size.
|
|
*
|
|
* Waker/wakee being client/server, worker/dispatcher, interrupt source or
|
|
* whatever is irrelevant, spread criteria is apparent partner count exceeds
|
|
* socket size.
|
|
*/
|
|
static int wake_wide(struct task_struct *p)
|
|
{
|
|
unsigned int master = current->wakee_flips;
|
|
unsigned int slave = p->wakee_flips;
|
|
int factor = __this_cpu_read(sd_llc_size);
|
|
|
|
if (master < slave)
|
|
swap(master, slave);
|
|
if (slave < factor || master < slave * factor)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* The purpose of wake_affine() is to quickly determine on which CPU we can run
|
|
* soonest. For the purpose of speed we only consider the waking and previous
|
|
* CPU.
|
|
*
|
|
* wake_affine_idle() - only considers 'now', it check if the waking CPU is
|
|
* cache-affine and is (or will be) idle.
|
|
*
|
|
* wake_affine_weight() - considers the weight to reflect the average
|
|
* scheduling latency of the CPUs. This seems to work
|
|
* for the overloaded case.
|
|
*/
|
|
static int
|
|
wake_affine_idle(int this_cpu, int prev_cpu, int sync)
|
|
{
|
|
/*
|
|
* If this_cpu is idle, it implies the wakeup is from interrupt
|
|
* context. Only allow the move if cache is shared. Otherwise an
|
|
* interrupt intensive workload could force all tasks onto one
|
|
* node depending on the IO topology or IRQ affinity settings.
|
|
*
|
|
* If the prev_cpu is idle and cache affine then avoid a migration.
|
|
* There is no guarantee that the cache hot data from an interrupt
|
|
* is more important than cache hot data on the prev_cpu and from
|
|
* a cpufreq perspective, it's better to have higher utilisation
|
|
* on one CPU.
|
|
*/
|
|
if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
|
|
return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
|
|
|
|
if (sync && cpu_rq(this_cpu)->nr_running == 1)
|
|
return this_cpu;
|
|
|
|
if (available_idle_cpu(prev_cpu))
|
|
return prev_cpu;
|
|
|
|
return nr_cpumask_bits;
|
|
}
|
|
|
|
static int
|
|
wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
|
|
int this_cpu, int prev_cpu, int sync)
|
|
{
|
|
s64 this_eff_load, prev_eff_load;
|
|
unsigned long task_load;
|
|
|
|
this_eff_load = cpu_load(cpu_rq(this_cpu));
|
|
|
|
if (sync) {
|
|
unsigned long current_load = task_h_load(current);
|
|
|
|
if (current_load > this_eff_load)
|
|
return this_cpu;
|
|
|
|
this_eff_load -= current_load;
|
|
}
|
|
|
|
task_load = task_h_load(p);
|
|
|
|
this_eff_load += task_load;
|
|
if (sched_feat(WA_BIAS))
|
|
this_eff_load *= 100;
|
|
this_eff_load *= capacity_of(prev_cpu);
|
|
|
|
prev_eff_load = cpu_load(cpu_rq(prev_cpu));
|
|
prev_eff_load -= task_load;
|
|
if (sched_feat(WA_BIAS))
|
|
prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
|
|
prev_eff_load *= capacity_of(this_cpu);
|
|
|
|
/*
|
|
* If sync, adjust the weight of prev_eff_load such that if
|
|
* prev_eff == this_eff that select_idle_sibling() will consider
|
|
* stacking the wakee on top of the waker if no other CPU is
|
|
* idle.
|
|
*/
|
|
if (sync)
|
|
prev_eff_load += 1;
|
|
|
|
return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
|
|
}
|
|
|
|
static int wake_affine(struct sched_domain *sd, struct task_struct *p,
|
|
int this_cpu, int prev_cpu, int sync)
|
|
{
|
|
int target = nr_cpumask_bits;
|
|
|
|
if (sched_feat(WA_IDLE))
|
|
target = wake_affine_idle(this_cpu, prev_cpu, sync);
|
|
|
|
if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
|
|
target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
|
|
|
|
schedstat_inc(p->stats.nr_wakeups_affine_attempts);
|
|
if (target != this_cpu)
|
|
return prev_cpu;
|
|
|
|
schedstat_inc(sd->ttwu_move_affine);
|
|
schedstat_inc(p->stats.nr_wakeups_affine);
|
|
return target;
|
|
}
|
|
|
|
static struct sched_group *
|
|
find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
|
|
|
|
/*
|
|
* find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
|
|
*/
|
|
static int
|
|
find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
|
|
{
|
|
unsigned long load, min_load = ULONG_MAX;
|
|
unsigned int min_exit_latency = UINT_MAX;
|
|
u64 latest_idle_timestamp = 0;
|
|
int least_loaded_cpu = this_cpu;
|
|
int shallowest_idle_cpu = -1;
|
|
int i;
|
|
|
|
/* Check if we have any choice: */
|
|
if (group->group_weight == 1)
|
|
return cpumask_first(sched_group_span(group));
|
|
|
|
/* Traverse only the allowed CPUs */
|
|
for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
|
|
struct rq *rq = cpu_rq(i);
|
|
|
|
if (!sched_core_cookie_match(rq, p))
|
|
continue;
|
|
|
|
if (sched_idle_cpu(i))
|
|
return i;
|
|
|
|
if (available_idle_cpu(i)) {
|
|
struct cpuidle_state *idle = idle_get_state(rq);
|
|
if (idle && idle->exit_latency < min_exit_latency) {
|
|
/*
|
|
* We give priority to a CPU whose idle state
|
|
* has the smallest exit latency irrespective
|
|
* of any idle timestamp.
|
|
*/
|
|
min_exit_latency = idle->exit_latency;
|
|
latest_idle_timestamp = rq->idle_stamp;
|
|
shallowest_idle_cpu = i;
|
|
} else if ((!idle || idle->exit_latency == min_exit_latency) &&
|
|
rq->idle_stamp > latest_idle_timestamp) {
|
|
/*
|
|
* If equal or no active idle state, then
|
|
* the most recently idled CPU might have
|
|
* a warmer cache.
|
|
*/
|
|
latest_idle_timestamp = rq->idle_stamp;
|
|
shallowest_idle_cpu = i;
|
|
}
|
|
} else if (shallowest_idle_cpu == -1) {
|
|
load = cpu_load(cpu_rq(i));
|
|
if (load < min_load) {
|
|
min_load = load;
|
|
least_loaded_cpu = i;
|
|
}
|
|
}
|
|
}
|
|
|
|
return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
|
|
}
|
|
|
|
static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
|
|
int cpu, int prev_cpu, int sd_flag)
|
|
{
|
|
int new_cpu = cpu;
|
|
|
|
if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
|
|
return prev_cpu;
|
|
|
|
/*
|
|
* We need task's util for cpu_util_without, sync it up to
|
|
* prev_cpu's last_update_time.
|
|
*/
|
|
if (!(sd_flag & SD_BALANCE_FORK))
|
|
sync_entity_load_avg(&p->se);
|
|
|
|
while (sd) {
|
|
struct sched_group *group;
|
|
struct sched_domain *tmp;
|
|
int weight;
|
|
|
|
if (!(sd->flags & sd_flag)) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
group = find_idlest_group(sd, p, cpu);
|
|
if (!group) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
new_cpu = find_idlest_group_cpu(group, p, cpu);
|
|
if (new_cpu == cpu) {
|
|
/* Now try balancing at a lower domain level of 'cpu': */
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
/* Now try balancing at a lower domain level of 'new_cpu': */
|
|
cpu = new_cpu;
|
|
weight = sd->span_weight;
|
|
sd = NULL;
|
|
for_each_domain(cpu, tmp) {
|
|
if (weight <= tmp->span_weight)
|
|
break;
|
|
if (tmp->flags & sd_flag)
|
|
sd = tmp;
|
|
}
|
|
}
|
|
|
|
return new_cpu;
|
|
}
|
|
|
|
static inline int __select_idle_cpu(int cpu, struct task_struct *p)
|
|
{
|
|
if ((available_idle_cpu(cpu) || sched_idle_cpu(cpu)) &&
|
|
sched_cpu_cookie_match(cpu_rq(cpu), p))
|
|
return cpu;
|
|
|
|
return -1;
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
DEFINE_STATIC_KEY_FALSE(sched_smt_present);
|
|
EXPORT_SYMBOL_GPL(sched_smt_present);
|
|
|
|
static inline void set_idle_cores(int cpu, int val)
|
|
{
|
|
struct sched_domain_shared *sds;
|
|
|
|
sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
|
|
if (sds)
|
|
WRITE_ONCE(sds->has_idle_cores, val);
|
|
}
|
|
|
|
static inline bool test_idle_cores(int cpu)
|
|
{
|
|
struct sched_domain_shared *sds;
|
|
|
|
sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
|
|
if (sds)
|
|
return READ_ONCE(sds->has_idle_cores);
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Scans the local SMT mask to see if the entire core is idle, and records this
|
|
* information in sd_llc_shared->has_idle_cores.
|
|
*
|
|
* Since SMT siblings share all cache levels, inspecting this limited remote
|
|
* state should be fairly cheap.
|
|
*/
|
|
void __update_idle_core(struct rq *rq)
|
|
{
|
|
int core = cpu_of(rq);
|
|
int cpu;
|
|
|
|
rcu_read_lock();
|
|
if (test_idle_cores(core))
|
|
goto unlock;
|
|
|
|
for_each_cpu(cpu, cpu_smt_mask(core)) {
|
|
if (cpu == core)
|
|
continue;
|
|
|
|
if (!available_idle_cpu(cpu))
|
|
goto unlock;
|
|
}
|
|
|
|
set_idle_cores(core, 1);
|
|
unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* Scan the entire LLC domain for idle cores; this dynamically switches off if
|
|
* there are no idle cores left in the system; tracked through
|
|
* sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
|
|
*/
|
|
static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
|
|
{
|
|
bool idle = true;
|
|
int cpu;
|
|
|
|
for_each_cpu(cpu, cpu_smt_mask(core)) {
|
|
if (!available_idle_cpu(cpu)) {
|
|
idle = false;
|
|
if (*idle_cpu == -1) {
|
|
if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
|
|
*idle_cpu = cpu;
|
|
break;
|
|
}
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
|
|
*idle_cpu = cpu;
|
|
}
|
|
|
|
if (idle)
|
|
return core;
|
|
|
|
cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Scan the local SMT mask for idle CPUs.
|
|
*/
|
|
static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
|
|
if (cpu == target)
|
|
continue;
|
|
/*
|
|
* Check if the CPU is in the LLC scheduling domain of @target.
|
|
* Due to isolcpus, there is no guarantee that all the siblings are in the domain.
|
|
*/
|
|
if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
|
|
continue;
|
|
if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
|
|
return cpu;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
#else /* CONFIG_SCHED_SMT */
|
|
|
|
static inline void set_idle_cores(int cpu, int val)
|
|
{
|
|
}
|
|
|
|
static inline bool test_idle_cores(int cpu)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
|
|
{
|
|
return __select_idle_cpu(core, p);
|
|
}
|
|
|
|
static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
|
|
{
|
|
return -1;
|
|
}
|
|
|
|
#endif /* CONFIG_SCHED_SMT */
|
|
|
|
/*
|
|
* Scan the LLC domain for idle CPUs; this is dynamically regulated by
|
|
* comparing the average scan cost (tracked in sd->avg_scan_cost) against the
|
|
* average idle time for this rq (as found in rq->avg_idle).
|
|
*/
|
|
static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool has_idle_core, int target)
|
|
{
|
|
struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
|
|
int i, cpu, idle_cpu = -1, nr = INT_MAX;
|
|
struct sched_domain_shared *sd_share;
|
|
|
|
cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
|
|
|
|
if (sched_feat(SIS_UTIL)) {
|
|
sd_share = rcu_dereference(per_cpu(sd_llc_shared, target));
|
|
if (sd_share) {
|
|
/* because !--nr is the condition to stop scan */
|
|
nr = READ_ONCE(sd_share->nr_idle_scan) + 1;
|
|
/* overloaded LLC is unlikely to have idle cpu/core */
|
|
if (nr == 1)
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
if (static_branch_unlikely(&sched_cluster_active)) {
|
|
struct sched_group *sg = sd->groups;
|
|
|
|
if (sg->flags & SD_CLUSTER) {
|
|
for_each_cpu_wrap(cpu, sched_group_span(sg), target + 1) {
|
|
if (!cpumask_test_cpu(cpu, cpus))
|
|
continue;
|
|
|
|
if (has_idle_core) {
|
|
i = select_idle_core(p, cpu, cpus, &idle_cpu);
|
|
if ((unsigned int)i < nr_cpumask_bits)
|
|
return i;
|
|
} else {
|
|
if (--nr <= 0)
|
|
return -1;
|
|
idle_cpu = __select_idle_cpu(cpu, p);
|
|
if ((unsigned int)idle_cpu < nr_cpumask_bits)
|
|
return idle_cpu;
|
|
}
|
|
}
|
|
cpumask_andnot(cpus, cpus, sched_group_span(sg));
|
|
}
|
|
}
|
|
|
|
for_each_cpu_wrap(cpu, cpus, target + 1) {
|
|
if (has_idle_core) {
|
|
i = select_idle_core(p, cpu, cpus, &idle_cpu);
|
|
if ((unsigned int)i < nr_cpumask_bits)
|
|
return i;
|
|
|
|
} else {
|
|
if (--nr <= 0)
|
|
return -1;
|
|
idle_cpu = __select_idle_cpu(cpu, p);
|
|
if ((unsigned int)idle_cpu < nr_cpumask_bits)
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (has_idle_core)
|
|
set_idle_cores(target, false);
|
|
|
|
return idle_cpu;
|
|
}
|
|
|
|
/*
|
|
* Scan the asym_capacity domain for idle CPUs; pick the first idle one on which
|
|
* the task fits. If no CPU is big enough, but there are idle ones, try to
|
|
* maximize capacity.
|
|
*/
|
|
static int
|
|
select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
|
|
{
|
|
unsigned long task_util, util_min, util_max, best_cap = 0;
|
|
int fits, best_fits = 0;
|
|
int cpu, best_cpu = -1;
|
|
struct cpumask *cpus;
|
|
|
|
cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
|
|
cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
|
|
|
|
task_util = task_util_est(p);
|
|
util_min = uclamp_eff_value(p, UCLAMP_MIN);
|
|
util_max = uclamp_eff_value(p, UCLAMP_MAX);
|
|
|
|
for_each_cpu_wrap(cpu, cpus, target) {
|
|
unsigned long cpu_cap = capacity_of(cpu);
|
|
|
|
if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))
|
|
continue;
|
|
|
|
fits = util_fits_cpu(task_util, util_min, util_max, cpu);
|
|
|
|
/* This CPU fits with all requirements */
|
|
if (fits > 0)
|
|
return cpu;
|
|
/*
|
|
* Only the min performance hint (i.e. uclamp_min) doesn't fit.
|
|
* Look for the CPU with best capacity.
|
|
*/
|
|
else if (fits < 0)
|
|
cpu_cap = arch_scale_cpu_capacity(cpu) - thermal_load_avg(cpu_rq(cpu));
|
|
|
|
/*
|
|
* First, select CPU which fits better (-1 being better than 0).
|
|
* Then, select the one with best capacity at same level.
|
|
*/
|
|
if ((fits < best_fits) ||
|
|
((fits == best_fits) && (cpu_cap > best_cap))) {
|
|
best_cap = cpu_cap;
|
|
best_cpu = cpu;
|
|
best_fits = fits;
|
|
}
|
|
}
|
|
|
|
return best_cpu;
|
|
}
|
|
|
|
static inline bool asym_fits_cpu(unsigned long util,
|
|
unsigned long util_min,
|
|
unsigned long util_max,
|
|
int cpu)
|
|
{
|
|
if (sched_asym_cpucap_active())
|
|
/*
|
|
* Return true only if the cpu fully fits the task requirements
|
|
* which include the utilization and the performance hints.
|
|
*/
|
|
return (util_fits_cpu(util, util_min, util_max, cpu) > 0);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Try and locate an idle core/thread in the LLC cache domain.
|
|
*/
|
|
static int select_idle_sibling(struct task_struct *p, int prev, int target)
|
|
{
|
|
bool has_idle_core = false;
|
|
struct sched_domain *sd;
|
|
unsigned long task_util, util_min, util_max;
|
|
int i, recent_used_cpu, prev_aff = -1;
|
|
|
|
/*
|
|
* On asymmetric system, update task utilization because we will check
|
|
* that the task fits with cpu's capacity.
|
|
*/
|
|
if (sched_asym_cpucap_active()) {
|
|
sync_entity_load_avg(&p->se);
|
|
task_util = task_util_est(p);
|
|
util_min = uclamp_eff_value(p, UCLAMP_MIN);
|
|
util_max = uclamp_eff_value(p, UCLAMP_MAX);
|
|
}
|
|
|
|
/*
|
|
* per-cpu select_rq_mask usage
|
|
*/
|
|
lockdep_assert_irqs_disabled();
|
|
|
|
if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
|
|
asym_fits_cpu(task_util, util_min, util_max, target))
|
|
return target;
|
|
|
|
/*
|
|
* If the previous CPU is cache affine and idle, don't be stupid:
|
|
*/
|
|
if (prev != target && cpus_share_cache(prev, target) &&
|
|
(available_idle_cpu(prev) || sched_idle_cpu(prev)) &&
|
|
asym_fits_cpu(task_util, util_min, util_max, prev)) {
|
|
|
|
if (!static_branch_unlikely(&sched_cluster_active) ||
|
|
cpus_share_resources(prev, target))
|
|
return prev;
|
|
|
|
prev_aff = prev;
|
|
}
|
|
|
|
/*
|
|
* Allow a per-cpu kthread to stack with the wakee if the
|
|
* kworker thread and the tasks previous CPUs are the same.
|
|
* The assumption is that the wakee queued work for the
|
|
* per-cpu kthread that is now complete and the wakeup is
|
|
* essentially a sync wakeup. An obvious example of this
|
|
* pattern is IO completions.
|
|
*/
|
|
if (is_per_cpu_kthread(current) &&
|
|
in_task() &&
|
|
prev == smp_processor_id() &&
|
|
this_rq()->nr_running <= 1 &&
|
|
asym_fits_cpu(task_util, util_min, util_max, prev)) {
|
|
return prev;
|
|
}
|
|
|
|
/* Check a recently used CPU as a potential idle candidate: */
|
|
recent_used_cpu = p->recent_used_cpu;
|
|
p->recent_used_cpu = prev;
|
|
if (recent_used_cpu != prev &&
|
|
recent_used_cpu != target &&
|
|
cpus_share_cache(recent_used_cpu, target) &&
|
|
(available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
|
|
cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
|
|
asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
|
|
|
|
if (!static_branch_unlikely(&sched_cluster_active) ||
|
|
cpus_share_resources(recent_used_cpu, target))
|
|
return recent_used_cpu;
|
|
|
|
} else {
|
|
recent_used_cpu = -1;
|
|
}
|
|
|
|
/*
|
|
* For asymmetric CPU capacity systems, our domain of interest is
|
|
* sd_asym_cpucapacity rather than sd_llc.
|
|
*/
|
|
if (sched_asym_cpucap_active()) {
|
|
sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
|
|
/*
|
|
* On an asymmetric CPU capacity system where an exclusive
|
|
* cpuset defines a symmetric island (i.e. one unique
|
|
* capacity_orig value through the cpuset), the key will be set
|
|
* but the CPUs within that cpuset will not have a domain with
|
|
* SD_ASYM_CPUCAPACITY. These should follow the usual symmetric
|
|
* capacity path.
|
|
*/
|
|
if (sd) {
|
|
i = select_idle_capacity(p, sd, target);
|
|
return ((unsigned)i < nr_cpumask_bits) ? i : target;
|
|
}
|
|
}
|
|
|
|
sd = rcu_dereference(per_cpu(sd_llc, target));
|
|
if (!sd)
|
|
return target;
|
|
|
|
if (sched_smt_active()) {
|
|
has_idle_core = test_idle_cores(target);
|
|
|
|
if (!has_idle_core && cpus_share_cache(prev, target)) {
|
|
i = select_idle_smt(p, sd, prev);
|
|
if ((unsigned int)i < nr_cpumask_bits)
|
|
return i;
|
|
}
|
|
}
|
|
|
|
i = select_idle_cpu(p, sd, has_idle_core, target);
|
|
if ((unsigned)i < nr_cpumask_bits)
|
|
return i;
|
|
|
|
/*
|
|
* For cluster machines which have lower sharing cache like L2 or
|
|
* LLC Tag, we tend to find an idle CPU in the target's cluster
|
|
* first. But prev_cpu or recent_used_cpu may also be a good candidate,
|
|
* use them if possible when no idle CPU found in select_idle_cpu().
|
|
*/
|
|
if ((unsigned int)prev_aff < nr_cpumask_bits)
|
|
return prev_aff;
|
|
if ((unsigned int)recent_used_cpu < nr_cpumask_bits)
|
|
return recent_used_cpu;
|
|
|
|
return target;
|
|
}
|
|
|
|
/**
|
|
* cpu_util() - Estimates the amount of CPU capacity used by CFS tasks.
|
|
* @cpu: the CPU to get the utilization for
|
|
* @p: task for which the CPU utilization should be predicted or NULL
|
|
* @dst_cpu: CPU @p migrates to, -1 if @p moves from @cpu or @p == NULL
|
|
* @boost: 1 to enable boosting, otherwise 0
|
|
*
|
|
* The unit of the return value must be the same as the one of CPU capacity
|
|
* so that CPU utilization can be compared with CPU capacity.
|
|
*
|
|
* CPU utilization is the sum of running time of runnable tasks plus the
|
|
* recent utilization of currently non-runnable tasks on that CPU.
|
|
* It represents the amount of CPU capacity currently used by CFS tasks in
|
|
* the range [0..max CPU capacity] with max CPU capacity being the CPU
|
|
* capacity at f_max.
|
|
*
|
|
* The estimated CPU utilization is defined as the maximum between CPU
|
|
* utilization and sum of the estimated utilization of the currently
|
|
* runnable tasks on that CPU. It preserves a utilization "snapshot" of
|
|
* previously-executed tasks, which helps better deduce how busy a CPU will
|
|
* be when a long-sleeping task wakes up. The contribution to CPU utilization
|
|
* of such a task would be significantly decayed at this point of time.
|
|
*
|
|
* Boosted CPU utilization is defined as max(CPU runnable, CPU utilization).
|
|
* CPU contention for CFS tasks can be detected by CPU runnable > CPU
|
|
* utilization. Boosting is implemented in cpu_util() so that internal
|
|
* users (e.g. EAS) can use it next to external users (e.g. schedutil),
|
|
* latter via cpu_util_cfs_boost().
|
|
*
|
|
* CPU utilization can be higher than the current CPU capacity
|
|
* (f_curr/f_max * max CPU capacity) or even the max CPU capacity because
|
|
* of rounding errors as well as task migrations or wakeups of new tasks.
|
|
* CPU utilization has to be capped to fit into the [0..max CPU capacity]
|
|
* range. Otherwise a group of CPUs (CPU0 util = 121% + CPU1 util = 80%)
|
|
* could be seen as over-utilized even though CPU1 has 20% of spare CPU
|
|
* capacity. CPU utilization is allowed to overshoot current CPU capacity
|
|
* though since this is useful for predicting the CPU capacity required
|
|
* after task migrations (scheduler-driven DVFS).
|
|
*
|
|
* Return: (Boosted) (estimated) utilization for the specified CPU.
|
|
*/
|
|
static unsigned long
|
|
cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
|
|
{
|
|
struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
|
|
unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
|
|
unsigned long runnable;
|
|
|
|
if (boost) {
|
|
runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
|
|
util = max(util, runnable);
|
|
}
|
|
|
|
/*
|
|
* If @dst_cpu is -1 or @p migrates from @cpu to @dst_cpu remove its
|
|
* contribution. If @p migrates from another CPU to @cpu add its
|
|
* contribution. In all the other cases @cpu is not impacted by the
|
|
* migration so its util_avg is already correct.
|
|
*/
|
|
if (p && task_cpu(p) == cpu && dst_cpu != cpu)
|
|
lsub_positive(&util, task_util(p));
|
|
else if (p && task_cpu(p) != cpu && dst_cpu == cpu)
|
|
util += task_util(p);
|
|
|
|
if (sched_feat(UTIL_EST)) {
|
|
unsigned long util_est;
|
|
|
|
util_est = READ_ONCE(cfs_rq->avg.util_est);
|
|
|
|
/*
|
|
* During wake-up @p isn't enqueued yet and doesn't contribute
|
|
* to any cpu_rq(cpu)->cfs.avg.util_est.
|
|
* If @dst_cpu == @cpu add it to "simulate" cpu_util after @p
|
|
* has been enqueued.
|
|
*
|
|
* During exec (@dst_cpu = -1) @p is enqueued and does
|
|
* contribute to cpu_rq(cpu)->cfs.util_est.
|
|
* Remove it to "simulate" cpu_util without @p's contribution.
|
|
*
|
|
* Despite the task_on_rq_queued(@p) check there is still a
|
|
* small window for a possible race when an exec
|
|
* select_task_rq_fair() races with LB's detach_task().
|
|
*
|
|
* detach_task()
|
|
* deactivate_task()
|
|
* p->on_rq = TASK_ON_RQ_MIGRATING;
|
|
* -------------------------------- A
|
|
* dequeue_task() \
|
|
* dequeue_task_fair() + Race Time
|
|
* util_est_dequeue() /
|
|
* -------------------------------- B
|
|
*
|
|
* The additional check "current == p" is required to further
|
|
* reduce the race window.
|
|
*/
|
|
if (dst_cpu == cpu)
|
|
util_est += _task_util_est(p);
|
|
else if (p && unlikely(task_on_rq_queued(p) || current == p))
|
|
lsub_positive(&util_est, _task_util_est(p));
|
|
|
|
util = max(util, util_est);
|
|
}
|
|
|
|
return min(util, arch_scale_cpu_capacity(cpu));
|
|
}
|
|
|
|
unsigned long cpu_util_cfs(int cpu)
|
|
{
|
|
return cpu_util(cpu, NULL, -1, 0);
|
|
}
|
|
|
|
unsigned long cpu_util_cfs_boost(int cpu)
|
|
{
|
|
return cpu_util(cpu, NULL, -1, 1);
|
|
}
|
|
|
|
/*
|
|
* cpu_util_without: compute cpu utilization without any contributions from *p
|
|
* @cpu: the CPU which utilization is requested
|
|
* @p: the task which utilization should be discounted
|
|
*
|
|
* The utilization of a CPU is defined by the utilization of tasks currently
|
|
* enqueued on that CPU as well as tasks which are currently sleeping after an
|
|
* execution on that CPU.
|
|
*
|
|
* This method returns the utilization of the specified CPU by discounting the
|
|
* utilization of the specified task, whenever the task is currently
|
|
* contributing to the CPU utilization.
|
|
*/
|
|
static unsigned long cpu_util_without(int cpu, struct task_struct *p)
|
|
{
|
|
/* Task has no contribution or is new */
|
|
if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
|
|
p = NULL;
|
|
|
|
return cpu_util(cpu, p, -1, 0);
|
|
}
|
|
|
|
/*
|
|
* energy_env - Utilization landscape for energy estimation.
|
|
* @task_busy_time: Utilization contribution by the task for which we test the
|
|
* placement. Given by eenv_task_busy_time().
|
|
* @pd_busy_time: Utilization of the whole perf domain without the task
|
|
* contribution. Given by eenv_pd_busy_time().
|
|
* @cpu_cap: Maximum CPU capacity for the perf domain.
|
|
* @pd_cap: Entire perf domain capacity. (pd->nr_cpus * cpu_cap).
|
|
*/
|
|
struct energy_env {
|
|
unsigned long task_busy_time;
|
|
unsigned long pd_busy_time;
|
|
unsigned long cpu_cap;
|
|
unsigned long pd_cap;
|
|
};
|
|
|
|
/*
|
|
* Compute the task busy time for compute_energy(). This time cannot be
|
|
* injected directly into effective_cpu_util() because of the IRQ scaling.
|
|
* The latter only makes sense with the most recent CPUs where the task has
|
|
* run.
|
|
*/
|
|
static inline void eenv_task_busy_time(struct energy_env *eenv,
|
|
struct task_struct *p, int prev_cpu)
|
|
{
|
|
unsigned long busy_time, max_cap = arch_scale_cpu_capacity(prev_cpu);
|
|
unsigned long irq = cpu_util_irq(cpu_rq(prev_cpu));
|
|
|
|
if (unlikely(irq >= max_cap))
|
|
busy_time = max_cap;
|
|
else
|
|
busy_time = scale_irq_capacity(task_util_est(p), irq, max_cap);
|
|
|
|
eenv->task_busy_time = busy_time;
|
|
}
|
|
|
|
/*
|
|
* Compute the perf_domain (PD) busy time for compute_energy(). Based on the
|
|
* utilization for each @pd_cpus, it however doesn't take into account
|
|
* clamping since the ratio (utilization / cpu_capacity) is already enough to
|
|
* scale the EM reported power consumption at the (eventually clamped)
|
|
* cpu_capacity.
|
|
*
|
|
* The contribution of the task @p for which we want to estimate the
|
|
* energy cost is removed (by cpu_util()) and must be calculated
|
|
* separately (see eenv_task_busy_time). This ensures:
|
|
*
|
|
* - A stable PD utilization, no matter which CPU of that PD we want to place
|
|
* the task on.
|
|
*
|
|
* - A fair comparison between CPUs as the task contribution (task_util())
|
|
* will always be the same no matter which CPU utilization we rely on
|
|
* (util_avg or util_est).
|
|
*
|
|
* Set @eenv busy time for the PD that spans @pd_cpus. This busy time can't
|
|
* exceed @eenv->pd_cap.
|
|
*/
|
|
static inline void eenv_pd_busy_time(struct energy_env *eenv,
|
|
struct cpumask *pd_cpus,
|
|
struct task_struct *p)
|
|
{
|
|
unsigned long busy_time = 0;
|
|
int cpu;
|
|
|
|
for_each_cpu(cpu, pd_cpus) {
|
|
unsigned long util = cpu_util(cpu, p, -1, 0);
|
|
|
|
busy_time += effective_cpu_util(cpu, util, NULL, NULL);
|
|
}
|
|
|
|
eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
|
|
}
|
|
|
|
/*
|
|
* Compute the maximum utilization for compute_energy() when the task @p
|
|
* is placed on the cpu @dst_cpu.
|
|
*
|
|
* Returns the maximum utilization among @eenv->cpus. This utilization can't
|
|
* exceed @eenv->cpu_cap.
|
|
*/
|
|
static inline unsigned long
|
|
eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
|
|
struct task_struct *p, int dst_cpu)
|
|
{
|
|
unsigned long max_util = 0;
|
|
int cpu;
|
|
|
|
for_each_cpu(cpu, pd_cpus) {
|
|
struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
|
|
unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
|
|
unsigned long eff_util, min, max;
|
|
|
|
/*
|
|
* Performance domain frequency: utilization clamping
|
|
* must be considered since it affects the selection
|
|
* of the performance domain frequency.
|
|
* NOTE: in case RT tasks are running, by default the
|
|
* FREQUENCY_UTIL's utilization can be max OPP.
|
|
*/
|
|
eff_util = effective_cpu_util(cpu, util, &min, &max);
|
|
|
|
/* Task's uclamp can modify min and max value */
|
|
if (tsk && uclamp_is_used()) {
|
|
min = max(min, uclamp_eff_value(p, UCLAMP_MIN));
|
|
|
|
/*
|
|
* If there is no active max uclamp constraint,
|
|
* directly use task's one, otherwise keep max.
|
|
*/
|
|
if (uclamp_rq_is_idle(cpu_rq(cpu)))
|
|
max = uclamp_eff_value(p, UCLAMP_MAX);
|
|
else
|
|
max = max(max, uclamp_eff_value(p, UCLAMP_MAX));
|
|
}
|
|
|
|
eff_util = sugov_effective_cpu_perf(cpu, eff_util, min, max);
|
|
max_util = max(max_util, eff_util);
|
|
}
|
|
|
|
return min(max_util, eenv->cpu_cap);
|
|
}
|
|
|
|
/*
|
|
* compute_energy(): Use the Energy Model to estimate the energy that @pd would
|
|
* consume for a given utilization landscape @eenv. When @dst_cpu < 0, the task
|
|
* contribution is ignored.
|
|
*/
|
|
static inline unsigned long
|
|
compute_energy(struct energy_env *eenv, struct perf_domain *pd,
|
|
struct cpumask *pd_cpus, struct task_struct *p, int dst_cpu)
|
|
{
|
|
unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
|
|
unsigned long busy_time = eenv->pd_busy_time;
|
|
unsigned long energy;
|
|
|
|
if (dst_cpu >= 0)
|
|
busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
|
|
|
|
energy = em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
|
|
|
|
trace_sched_compute_energy_tp(p, dst_cpu, energy, max_util, busy_time);
|
|
|
|
return energy;
|
|
}
|
|
|
|
/*
|
|
* find_energy_efficient_cpu(): Find most energy-efficient target CPU for the
|
|
* waking task. find_energy_efficient_cpu() looks for the CPU with maximum
|
|
* spare capacity in each performance domain and uses it as a potential
|
|
* candidate to execute the task. Then, it uses the Energy Model to figure
|
|
* out which of the CPU candidates is the most energy-efficient.
|
|
*
|
|
* The rationale for this heuristic is as follows. In a performance domain,
|
|
* all the most energy efficient CPU candidates (according to the Energy
|
|
* Model) are those for which we'll request a low frequency. When there are
|
|
* several CPUs for which the frequency request will be the same, we don't
|
|
* have enough data to break the tie between them, because the Energy Model
|
|
* only includes active power costs. With this model, if we assume that
|
|
* frequency requests follow utilization (e.g. using schedutil), the CPU with
|
|
* the maximum spare capacity in a performance domain is guaranteed to be among
|
|
* the best candidates of the performance domain.
|
|
*
|
|
* In practice, it could be preferable from an energy standpoint to pack
|
|
* small tasks on a CPU in order to let other CPUs go in deeper idle states,
|
|
* but that could also hurt our chances to go cluster idle, and we have no
|
|
* ways to tell with the current Energy Model if this is actually a good
|
|
* idea or not. So, find_energy_efficient_cpu() basically favors
|
|
* cluster-packing, and spreading inside a cluster. That should at least be
|
|
* a good thing for latency, and this is consistent with the idea that most
|
|
* of the energy savings of EAS come from the asymmetry of the system, and
|
|
* not so much from breaking the tie between identical CPUs. That's also the
|
|
* reason why EAS is enabled in the topology code only for systems where
|
|
* SD_ASYM_CPUCAPACITY is set.
|
|
*
|
|
* NOTE: Forkees are not accepted in the energy-aware wake-up path because
|
|
* they don't have any useful utilization data yet and it's not possible to
|
|
* forecast their impact on energy consumption. Consequently, they will be
|
|
* placed by find_idlest_cpu() on the least loaded CPU, which might turn out
|
|
* to be energy-inefficient in some use-cases. The alternative would be to
|
|
* bias new tasks towards specific types of CPUs first, or to try to infer
|
|
* their util_avg from the parent task, but those heuristics could hurt
|
|
* other use-cases too. So, until someone finds a better way to solve this,
|
|
* let's keep things simple by re-using the existing slow path.
|
|
*/
|
|
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
|
|
{
|
|
struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
|
|
unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
|
|
unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0;
|
|
unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024;
|
|
struct root_domain *rd = this_rq()->rd;
|
|
int cpu, best_energy_cpu, target = -1;
|
|
int prev_fits = -1, best_fits = -1;
|
|
unsigned long best_thermal_cap = 0;
|
|
unsigned long prev_thermal_cap = 0;
|
|
struct sched_domain *sd;
|
|
struct perf_domain *pd;
|
|
struct energy_env eenv;
|
|
|
|
rcu_read_lock();
|
|
pd = rcu_dereference(rd->pd);
|
|
if (!pd || READ_ONCE(rd->overutilized))
|
|
goto unlock;
|
|
|
|
/*
|
|
* Energy-aware wake-up happens on the lowest sched_domain starting
|
|
* from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
|
|
*/
|
|
sd = rcu_dereference(*this_cpu_ptr(&sd_asym_cpucapacity));
|
|
while (sd && !cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
|
|
sd = sd->parent;
|
|
if (!sd)
|
|
goto unlock;
|
|
|
|
target = prev_cpu;
|
|
|
|
sync_entity_load_avg(&p->se);
|
|
if (!task_util_est(p) && p_util_min == 0)
|
|
goto unlock;
|
|
|
|
eenv_task_busy_time(&eenv, p, prev_cpu);
|
|
|
|
for (; pd; pd = pd->next) {
|
|
unsigned long util_min = p_util_min, util_max = p_util_max;
|
|
unsigned long cpu_cap, cpu_thermal_cap, util;
|
|
long prev_spare_cap = -1, max_spare_cap = -1;
|
|
unsigned long rq_util_min, rq_util_max;
|
|
unsigned long cur_delta, base_energy;
|
|
int max_spare_cap_cpu = -1;
|
|
int fits, max_fits = -1;
|
|
|
|
cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
|
|
|
|
if (cpumask_empty(cpus))
|
|
continue;
|
|
|
|
/* Account thermal pressure for the energy estimation */
|
|
cpu = cpumask_first(cpus);
|
|
cpu_thermal_cap = arch_scale_cpu_capacity(cpu);
|
|
cpu_thermal_cap -= arch_scale_thermal_pressure(cpu);
|
|
|
|
eenv.cpu_cap = cpu_thermal_cap;
|
|
eenv.pd_cap = 0;
|
|
|
|
for_each_cpu(cpu, cpus) {
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
eenv.pd_cap += cpu_thermal_cap;
|
|
|
|
if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
|
|
continue;
|
|
|
|
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
|
|
continue;
|
|
|
|
util = cpu_util(cpu, p, cpu, 0);
|
|
cpu_cap = capacity_of(cpu);
|
|
|
|
/*
|
|
* Skip CPUs that cannot satisfy the capacity request.
|
|
* IOW, placing the task there would make the CPU
|
|
* overutilized. Take uclamp into account to see how
|
|
* much capacity we can get out of the CPU; this is
|
|
* aligned with sched_cpu_util().
|
|
*/
|
|
if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
|
|
/*
|
|
* Open code uclamp_rq_util_with() except for
|
|
* the clamp() part. Ie: apply max aggregation
|
|
* only. util_fits_cpu() logic requires to
|
|
* operate on non clamped util but must use the
|
|
* max-aggregated uclamp_{min, max}.
|
|
*/
|
|
rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
|
|
rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
|
|
|
|
util_min = max(rq_util_min, p_util_min);
|
|
util_max = max(rq_util_max, p_util_max);
|
|
}
|
|
|
|
fits = util_fits_cpu(util, util_min, util_max, cpu);
|
|
if (!fits)
|
|
continue;
|
|
|
|
lsub_positive(&cpu_cap, util);
|
|
|
|
if (cpu == prev_cpu) {
|
|
/* Always use prev_cpu as a candidate. */
|
|
prev_spare_cap = cpu_cap;
|
|
prev_fits = fits;
|
|
} else if ((fits > max_fits) ||
|
|
((fits == max_fits) && ((long)cpu_cap > max_spare_cap))) {
|
|
/*
|
|
* Find the CPU with the maximum spare capacity
|
|
* among the remaining CPUs in the performance
|
|
* domain.
|
|
*/
|
|
max_spare_cap = cpu_cap;
|
|
max_spare_cap_cpu = cpu;
|
|
max_fits = fits;
|
|
}
|
|
}
|
|
|
|
if (max_spare_cap_cpu < 0 && prev_spare_cap < 0)
|
|
continue;
|
|
|
|
eenv_pd_busy_time(&eenv, cpus, p);
|
|
/* Compute the 'base' energy of the pd, without @p */
|
|
base_energy = compute_energy(&eenv, pd, cpus, p, -1);
|
|
|
|
/* Evaluate the energy impact of using prev_cpu. */
|
|
if (prev_spare_cap > -1) {
|
|
prev_delta = compute_energy(&eenv, pd, cpus, p,
|
|
prev_cpu);
|
|
/* CPU utilization has changed */
|
|
if (prev_delta < base_energy)
|
|
goto unlock;
|
|
prev_delta -= base_energy;
|
|
prev_thermal_cap = cpu_thermal_cap;
|
|
best_delta = min(best_delta, prev_delta);
|
|
}
|
|
|
|
/* Evaluate the energy impact of using max_spare_cap_cpu. */
|
|
if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) {
|
|
/* Current best energy cpu fits better */
|
|
if (max_fits < best_fits)
|
|
continue;
|
|
|
|
/*
|
|
* Both don't fit performance hint (i.e. uclamp_min)
|
|
* but best energy cpu has better capacity.
|
|
*/
|
|
if ((max_fits < 0) &&
|
|
(cpu_thermal_cap <= best_thermal_cap))
|
|
continue;
|
|
|
|
cur_delta = compute_energy(&eenv, pd, cpus, p,
|
|
max_spare_cap_cpu);
|
|
/* CPU utilization has changed */
|
|
if (cur_delta < base_energy)
|
|
goto unlock;
|
|
cur_delta -= base_energy;
|
|
|
|
/*
|
|
* Both fit for the task but best energy cpu has lower
|
|
* energy impact.
|
|
*/
|
|
if ((max_fits > 0) && (best_fits > 0) &&
|
|
(cur_delta >= best_delta))
|
|
continue;
|
|
|
|
best_delta = cur_delta;
|
|
best_energy_cpu = max_spare_cap_cpu;
|
|
best_fits = max_fits;
|
|
best_thermal_cap = cpu_thermal_cap;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if ((best_fits > prev_fits) ||
|
|
((best_fits > 0) && (best_delta < prev_delta)) ||
|
|
((best_fits < 0) && (best_thermal_cap > prev_thermal_cap)))
|
|
target = best_energy_cpu;
|
|
|
|
return target;
|
|
|
|
unlock:
|
|
rcu_read_unlock();
|
|
|
|
return target;
|
|
}
|
|
|
|
/*
|
|
* select_task_rq_fair: Select target runqueue for the waking task in domains
|
|
* that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
|
|
* SD_BALANCE_FORK, or SD_BALANCE_EXEC.
|
|
*
|
|
* Balances load by selecting the idlest CPU in the idlest group, or under
|
|
* certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
|
|
*
|
|
* Returns the target CPU number.
|
|
*/
|
|
static int
|
|
select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
|
|
{
|
|
int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
|
|
struct sched_domain *tmp, *sd = NULL;
|
|
int cpu = smp_processor_id();
|
|
int new_cpu = prev_cpu;
|
|
int want_affine = 0;
|
|
/* SD_flags and WF_flags share the first nibble */
|
|
int sd_flag = wake_flags & 0xF;
|
|
|
|
/*
|
|
* required for stable ->cpus_allowed
|
|
*/
|
|
lockdep_assert_held(&p->pi_lock);
|
|
if (wake_flags & WF_TTWU) {
|
|
record_wakee(p);
|
|
|
|
if ((wake_flags & WF_CURRENT_CPU) &&
|
|
cpumask_test_cpu(cpu, p->cpus_ptr))
|
|
return cpu;
|
|
|
|
if (sched_energy_enabled()) {
|
|
new_cpu = find_energy_efficient_cpu(p, prev_cpu);
|
|
if (new_cpu >= 0)
|
|
return new_cpu;
|
|
new_cpu = prev_cpu;
|
|
}
|
|
|
|
want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);
|
|
}
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, tmp) {
|
|
/*
|
|
* If both 'cpu' and 'prev_cpu' are part of this domain,
|
|
* cpu is a valid SD_WAKE_AFFINE target.
|
|
*/
|
|
if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
|
|
cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
|
|
if (cpu != prev_cpu)
|
|
new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
|
|
|
|
sd = NULL; /* Prefer wake_affine over balance flags */
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Usually only true for WF_EXEC and WF_FORK, as sched_domains
|
|
* usually do not have SD_BALANCE_WAKE set. That means wakeup
|
|
* will usually go to the fast path.
|
|
*/
|
|
if (tmp->flags & sd_flag)
|
|
sd = tmp;
|
|
else if (!want_affine)
|
|
break;
|
|
}
|
|
|
|
if (unlikely(sd)) {
|
|
/* Slow path */
|
|
new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
|
|
} else if (wake_flags & WF_TTWU) { /* XXX always ? */
|
|
/* Fast path */
|
|
new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return new_cpu;
|
|
}
|
|
|
|
/*
|
|
* Called immediately before a task is migrated to a new CPU; task_cpu(p) and
|
|
* cfs_rq_of(p) references at time of call are still valid and identify the
|
|
* previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
|
|
*/
|
|
static void migrate_task_rq_fair(struct task_struct *p, int new_cpu)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
if (!task_on_rq_migrating(p)) {
|
|
remove_entity_load_avg(se);
|
|
|
|
/*
|
|
* Here, the task's PELT values have been updated according to
|
|
* the current rq's clock. But if that clock hasn't been
|
|
* updated in a while, a substantial idle time will be missed,
|
|
* leading to an inflation after wake-up on the new rq.
|
|
*
|
|
* Estimate the missing time from the cfs_rq last_update_time
|
|
* and update sched_avg to improve the PELT continuity after
|
|
* migration.
|
|
*/
|
|
migrate_se_pelt_lag(se);
|
|
}
|
|
|
|
/* Tell new CPU we are migrated */
|
|
se->avg.last_update_time = 0;
|
|
|
|
update_scan_period(p, new_cpu);
|
|
}
|
|
|
|
static void task_dead_fair(struct task_struct *p)
|
|
{
|
|
remove_entity_load_avg(&p->se);
|
|
}
|
|
|
|
static int
|
|
balance_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
|
|
{
|
|
if (rq->nr_running)
|
|
return 1;
|
|
|
|
return newidle_balance(rq, rf) != 0;
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void set_next_buddy(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
if (SCHED_WARN_ON(!se->on_rq))
|
|
return;
|
|
if (se_is_idle(se))
|
|
return;
|
|
cfs_rq_of(se)->next = se;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int wake_flags)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct sched_entity *se = &curr->se, *pse = &p->se;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
int cse_is_idle, pse_is_idle;
|
|
|
|
if (unlikely(se == pse))
|
|
return;
|
|
|
|
/*
|
|
* This is possible from callers such as attach_tasks(), in which we
|
|
* unconditionally wakeup_preempt() after an enqueue (which may have
|
|
* lead to a throttle). This both saves work and prevents false
|
|
* next-buddy nomination below.
|
|
*/
|
|
if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
|
|
return;
|
|
|
|
if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK)) {
|
|
set_next_buddy(pse);
|
|
}
|
|
|
|
/*
|
|
* We can come here with TIF_NEED_RESCHED already set from new task
|
|
* wake up path.
|
|
*
|
|
* Note: this also catches the edge-case of curr being in a throttled
|
|
* group (e.g. via set_curr_task), since update_curr() (in the
|
|
* enqueue of curr) will have resulted in resched being set. This
|
|
* prevents us from potentially nominating it as a false LAST_BUDDY
|
|
* below.
|
|
*/
|
|
if (test_tsk_need_resched(curr))
|
|
return;
|
|
|
|
/* Idle tasks are by definition preempted by non-idle tasks. */
|
|
if (unlikely(task_has_idle_policy(curr)) &&
|
|
likely(!task_has_idle_policy(p)))
|
|
goto preempt;
|
|
|
|
/*
|
|
* Batch and idle tasks do not preempt non-idle tasks (their preemption
|
|
* is driven by the tick):
|
|
*/
|
|
if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
|
|
return;
|
|
|
|
find_matching_se(&se, &pse);
|
|
WARN_ON_ONCE(!pse);
|
|
|
|
cse_is_idle = se_is_idle(se);
|
|
pse_is_idle = se_is_idle(pse);
|
|
|
|
/*
|
|
* Preempt an idle group in favor of a non-idle group (and don't preempt
|
|
* in the inverse case).
|
|
*/
|
|
if (cse_is_idle && !pse_is_idle)
|
|
goto preempt;
|
|
if (cse_is_idle != pse_is_idle)
|
|
return;
|
|
|
|
cfs_rq = cfs_rq_of(se);
|
|
update_curr(cfs_rq);
|
|
|
|
/*
|
|
* XXX pick_eevdf(cfs_rq) != se ?
|
|
*/
|
|
if (pick_eevdf(cfs_rq) == pse)
|
|
goto preempt;
|
|
|
|
return;
|
|
|
|
preempt:
|
|
resched_curr(rq);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static struct task_struct *pick_task_fair(struct rq *rq)
|
|
{
|
|
struct sched_entity *se;
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
again:
|
|
cfs_rq = &rq->cfs;
|
|
if (!cfs_rq->nr_running)
|
|
return NULL;
|
|
|
|
do {
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
|
|
/* When we pick for a remote RQ, we'll not have done put_prev_entity() */
|
|
if (curr) {
|
|
if (curr->on_rq)
|
|
update_curr(cfs_rq);
|
|
else
|
|
curr = NULL;
|
|
|
|
if (unlikely(check_cfs_rq_runtime(cfs_rq)))
|
|
goto again;
|
|
}
|
|
|
|
se = pick_next_entity(cfs_rq);
|
|
cfs_rq = group_cfs_rq(se);
|
|
} while (cfs_rq);
|
|
|
|
return task_of(se);
|
|
}
|
|
#endif
|
|
|
|
struct task_struct *
|
|
pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
|
|
{
|
|
struct cfs_rq *cfs_rq = &rq->cfs;
|
|
struct sched_entity *se;
|
|
struct task_struct *p;
|
|
int new_tasks;
|
|
|
|
again:
|
|
if (!sched_fair_runnable(rq))
|
|
goto idle;
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
if (!prev || prev->sched_class != &fair_sched_class)
|
|
goto simple;
|
|
|
|
/*
|
|
* Because of the set_next_buddy() in dequeue_task_fair() it is rather
|
|
* likely that a next task is from the same cgroup as the current.
|
|
*
|
|
* Therefore attempt to avoid putting and setting the entire cgroup
|
|
* hierarchy, only change the part that actually changes.
|
|
*/
|
|
|
|
do {
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
|
|
/*
|
|
* Since we got here without doing put_prev_entity() we also
|
|
* have to consider cfs_rq->curr. If it is still a runnable
|
|
* entity, update_curr() will update its vruntime, otherwise
|
|
* forget we've ever seen it.
|
|
*/
|
|
if (curr) {
|
|
if (curr->on_rq)
|
|
update_curr(cfs_rq);
|
|
else
|
|
curr = NULL;
|
|
|
|
/*
|
|
* This call to check_cfs_rq_runtime() will do the
|
|
* throttle and dequeue its entity in the parent(s).
|
|
* Therefore the nr_running test will indeed
|
|
* be correct.
|
|
*/
|
|
if (unlikely(check_cfs_rq_runtime(cfs_rq))) {
|
|
cfs_rq = &rq->cfs;
|
|
|
|
if (!cfs_rq->nr_running)
|
|
goto idle;
|
|
|
|
goto simple;
|
|
}
|
|
}
|
|
|
|
se = pick_next_entity(cfs_rq);
|
|
cfs_rq = group_cfs_rq(se);
|
|
} while (cfs_rq);
|
|
|
|
p = task_of(se);
|
|
|
|
/*
|
|
* Since we haven't yet done put_prev_entity and if the selected task
|
|
* is a different task than we started out with, try and touch the
|
|
* least amount of cfs_rqs.
|
|
*/
|
|
if (prev != p) {
|
|
struct sched_entity *pse = &prev->se;
|
|
|
|
while (!(cfs_rq = is_same_group(se, pse))) {
|
|
int se_depth = se->depth;
|
|
int pse_depth = pse->depth;
|
|
|
|
if (se_depth <= pse_depth) {
|
|
put_prev_entity(cfs_rq_of(pse), pse);
|
|
pse = parent_entity(pse);
|
|
}
|
|
if (se_depth >= pse_depth) {
|
|
set_next_entity(cfs_rq_of(se), se);
|
|
se = parent_entity(se);
|
|
}
|
|
}
|
|
|
|
put_prev_entity(cfs_rq, pse);
|
|
set_next_entity(cfs_rq, se);
|
|
}
|
|
|
|
goto done;
|
|
simple:
|
|
#endif
|
|
if (prev)
|
|
put_prev_task(rq, prev);
|
|
|
|
do {
|
|
se = pick_next_entity(cfs_rq);
|
|
set_next_entity(cfs_rq, se);
|
|
cfs_rq = group_cfs_rq(se);
|
|
} while (cfs_rq);
|
|
|
|
p = task_of(se);
|
|
|
|
done: __maybe_unused;
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Move the next running task to the front of
|
|
* the list, so our cfs_tasks list becomes MRU
|
|
* one.
|
|
*/
|
|
list_move(&p->se.group_node, &rq->cfs_tasks);
|
|
#endif
|
|
|
|
if (hrtick_enabled_fair(rq))
|
|
hrtick_start_fair(rq, p);
|
|
|
|
update_misfit_status(p, rq);
|
|
sched_fair_update_stop_tick(rq, p);
|
|
|
|
return p;
|
|
|
|
idle:
|
|
if (!rf)
|
|
return NULL;
|
|
|
|
new_tasks = newidle_balance(rq, rf);
|
|
|
|
/*
|
|
* Because newidle_balance() releases (and re-acquires) rq->lock, it is
|
|
* possible for any higher priority task to appear. In that case we
|
|
* must re-start the pick_next_entity() loop.
|
|
*/
|
|
if (new_tasks < 0)
|
|
return RETRY_TASK;
|
|
|
|
if (new_tasks > 0)
|
|
goto again;
|
|
|
|
/*
|
|
* rq is about to be idle, check if we need to update the
|
|
* lost_idle_time of clock_pelt
|
|
*/
|
|
update_idle_rq_clock_pelt(rq);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct task_struct *__pick_next_task_fair(struct rq *rq)
|
|
{
|
|
return pick_next_task_fair(rq, NULL, NULL);
|
|
}
|
|
|
|
/*
|
|
* Account for a descheduled task:
|
|
*/
|
|
static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
|
|
{
|
|
struct sched_entity *se = &prev->se;
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
put_prev_entity(cfs_rq, se);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* sched_yield() is very simple
|
|
*/
|
|
static void yield_task_fair(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
struct sched_entity *se = &curr->se;
|
|
|
|
/*
|
|
* Are we the only task in the tree?
|
|
*/
|
|
if (unlikely(rq->nr_running == 1))
|
|
return;
|
|
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
update_rq_clock(rq);
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
/*
|
|
* Tell update_rq_clock() that we've just updated,
|
|
* so we don't do microscopic update in schedule()
|
|
* and double the fastpath cost.
|
|
*/
|
|
rq_clock_skip_update(rq);
|
|
|
|
se->deadline += calc_delta_fair(se->slice, se);
|
|
}
|
|
|
|
static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
/* throttled hierarchies are not runnable */
|
|
if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
|
|
return false;
|
|
|
|
/* Tell the scheduler that we'd really like pse to run next. */
|
|
set_next_buddy(se);
|
|
|
|
yield_task_fair(rq);
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/**************************************************
|
|
* Fair scheduling class load-balancing methods.
|
|
*
|
|
* BASICS
|
|
*
|
|
* The purpose of load-balancing is to achieve the same basic fairness the
|
|
* per-CPU scheduler provides, namely provide a proportional amount of compute
|
|
* time to each task. This is expressed in the following equation:
|
|
*
|
|
* W_i,n/P_i == W_j,n/P_j for all i,j (1)
|
|
*
|
|
* Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
|
|
* W_i,0 is defined as:
|
|
*
|
|
* W_i,0 = \Sum_j w_i,j (2)
|
|
*
|
|
* Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
|
|
* is derived from the nice value as per sched_prio_to_weight[].
|
|
*
|
|
* The weight average is an exponential decay average of the instantaneous
|
|
* weight:
|
|
*
|
|
* W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
|
|
*
|
|
* C_i is the compute capacity of CPU i, typically it is the
|
|
* fraction of 'recent' time available for SCHED_OTHER task execution. But it
|
|
* can also include other factors [XXX].
|
|
*
|
|
* To achieve this balance we define a measure of imbalance which follows
|
|
* directly from (1):
|
|
*
|
|
* imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4)
|
|
*
|
|
* We them move tasks around to minimize the imbalance. In the continuous
|
|
* function space it is obvious this converges, in the discrete case we get
|
|
* a few fun cases generally called infeasible weight scenarios.
|
|
*
|
|
* [XXX expand on:
|
|
* - infeasible weights;
|
|
* - local vs global optima in the discrete case. ]
|
|
*
|
|
*
|
|
* SCHED DOMAINS
|
|
*
|
|
* In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
|
|
* for all i,j solution, we create a tree of CPUs that follows the hardware
|
|
* topology where each level pairs two lower groups (or better). This results
|
|
* in O(log n) layers. Furthermore we reduce the number of CPUs going up the
|
|
* tree to only the first of the previous level and we decrease the frequency
|
|
* of load-balance at each level inv. proportional to the number of CPUs in
|
|
* the groups.
|
|
*
|
|
* This yields:
|
|
*
|
|
* log_2 n 1 n
|
|
* \Sum { --- * --- * 2^i } = O(n) (5)
|
|
* i = 0 2^i 2^i
|
|
* `- size of each group
|
|
* | | `- number of CPUs doing load-balance
|
|
* | `- freq
|
|
* `- sum over all levels
|
|
*
|
|
* Coupled with a limit on how many tasks we can migrate every balance pass,
|
|
* this makes (5) the runtime complexity of the balancer.
|
|
*
|
|
* An important property here is that each CPU is still (indirectly) connected
|
|
* to every other CPU in at most O(log n) steps:
|
|
*
|
|
* The adjacency matrix of the resulting graph is given by:
|
|
*
|
|
* log_2 n
|
|
* A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
|
|
* k = 0
|
|
*
|
|
* And you'll find that:
|
|
*
|
|
* A^(log_2 n)_i,j != 0 for all i,j (7)
|
|
*
|
|
* Showing there's indeed a path between every CPU in at most O(log n) steps.
|
|
* The task movement gives a factor of O(m), giving a convergence complexity
|
|
* of:
|
|
*
|
|
* O(nm log n), n := nr_cpus, m := nr_tasks (8)
|
|
*
|
|
*
|
|
* WORK CONSERVING
|
|
*
|
|
* In order to avoid CPUs going idle while there's still work to do, new idle
|
|
* balancing is more aggressive and has the newly idle CPU iterate up the domain
|
|
* tree itself instead of relying on other CPUs to bring it work.
|
|
*
|
|
* This adds some complexity to both (5) and (8) but it reduces the total idle
|
|
* time.
|
|
*
|
|
* [XXX more?]
|
|
*
|
|
*
|
|
* CGROUPS
|
|
*
|
|
* Cgroups make a horror show out of (2), instead of a simple sum we get:
|
|
*
|
|
* s_k,i
|
|
* W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
|
|
* S_k
|
|
*
|
|
* Where
|
|
*
|
|
* s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
|
|
*
|
|
* w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
|
|
*
|
|
* The big problem is S_k, its a global sum needed to compute a local (W_i)
|
|
* property.
|
|
*
|
|
* [XXX write more on how we solve this.. _after_ merging pjt's patches that
|
|
* rewrite all of this once again.]
|
|
*/
|
|
|
|
static unsigned long __read_mostly max_load_balance_interval = HZ/10;
|
|
|
|
enum fbq_type { regular, remote, all };
|
|
|
|
/*
|
|
* 'group_type' describes the group of CPUs at the moment of load balancing.
|
|
*
|
|
* The enum is ordered by pulling priority, with the group with lowest priority
|
|
* first so the group_type can simply be compared when selecting the busiest
|
|
* group. See update_sd_pick_busiest().
|
|
*/
|
|
enum group_type {
|
|
/* The group has spare capacity that can be used to run more tasks. */
|
|
group_has_spare = 0,
|
|
/*
|
|
* The group is fully used and the tasks don't compete for more CPU
|
|
* cycles. Nevertheless, some tasks might wait before running.
|
|
*/
|
|
group_fully_busy,
|
|
/*
|
|
* One task doesn't fit with CPU's capacity and must be migrated to a
|
|
* more powerful CPU.
|
|
*/
|
|
group_misfit_task,
|
|
/*
|
|
* Balance SMT group that's fully busy. Can benefit from migration
|
|
* a task on SMT with busy sibling to another CPU on idle core.
|
|
*/
|
|
group_smt_balance,
|
|
/*
|
|
* SD_ASYM_PACKING only: One local CPU with higher capacity is available,
|
|
* and the task should be migrated to it instead of running on the
|
|
* current CPU.
|
|
*/
|
|
group_asym_packing,
|
|
/*
|
|
* The tasks' affinity constraints previously prevented the scheduler
|
|
* from balancing the load across the system.
|
|
*/
|
|
group_imbalanced,
|
|
/*
|
|
* The CPU is overloaded and can't provide expected CPU cycles to all
|
|
* tasks.
|
|
*/
|
|
group_overloaded
|
|
};
|
|
|
|
enum migration_type {
|
|
migrate_load = 0,
|
|
migrate_util,
|
|
migrate_task,
|
|
migrate_misfit
|
|
};
|
|
|
|
#define LBF_ALL_PINNED 0x01
|
|
#define LBF_NEED_BREAK 0x02
|
|
#define LBF_DST_PINNED 0x04
|
|
#define LBF_SOME_PINNED 0x08
|
|
#define LBF_ACTIVE_LB 0x10
|
|
|
|
struct lb_env {
|
|
struct sched_domain *sd;
|
|
|
|
struct rq *src_rq;
|
|
int src_cpu;
|
|
|
|
int dst_cpu;
|
|
struct rq *dst_rq;
|
|
|
|
struct cpumask *dst_grpmask;
|
|
int new_dst_cpu;
|
|
enum cpu_idle_type idle;
|
|
long imbalance;
|
|
/* The set of CPUs under consideration for load-balancing */
|
|
struct cpumask *cpus;
|
|
|
|
unsigned int flags;
|
|
|
|
unsigned int loop;
|
|
unsigned int loop_break;
|
|
unsigned int loop_max;
|
|
|
|
enum fbq_type fbq_type;
|
|
enum migration_type migration_type;
|
|
struct list_head tasks;
|
|
};
|
|
|
|
/*
|
|
* Is this task likely cache-hot:
|
|
*/
|
|
static int task_hot(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
s64 delta;
|
|
|
|
lockdep_assert_rq_held(env->src_rq);
|
|
|
|
if (p->sched_class != &fair_sched_class)
|
|
return 0;
|
|
|
|
if (unlikely(task_has_idle_policy(p)))
|
|
return 0;
|
|
|
|
/* SMT siblings share cache */
|
|
if (env->sd->flags & SD_SHARE_CPUCAPACITY)
|
|
return 0;
|
|
|
|
/*
|
|
* Buddy candidates are cache hot:
|
|
*/
|
|
if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
|
|
(&p->se == cfs_rq_of(&p->se)->next))
|
|
return 1;
|
|
|
|
if (sysctl_sched_migration_cost == -1)
|
|
return 1;
|
|
|
|
/*
|
|
* Don't migrate task if the task's cookie does not match
|
|
* with the destination CPU's core cookie.
|
|
*/
|
|
if (!sched_core_cookie_match(cpu_rq(env->dst_cpu), p))
|
|
return 1;
|
|
|
|
if (sysctl_sched_migration_cost == 0)
|
|
return 0;
|
|
|
|
delta = rq_clock_task(env->src_rq) - p->se.exec_start;
|
|
|
|
return delta < (s64)sysctl_sched_migration_cost;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/*
|
|
* Returns 1, if task migration degrades locality
|
|
* Returns 0, if task migration improves locality i.e migration preferred.
|
|
* Returns -1, if task migration is not affected by locality.
|
|
*/
|
|
static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
struct numa_group *numa_group = rcu_dereference(p->numa_group);
|
|
unsigned long src_weight, dst_weight;
|
|
int src_nid, dst_nid, dist;
|
|
|
|
if (!static_branch_likely(&sched_numa_balancing))
|
|
return -1;
|
|
|
|
if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
|
|
return -1;
|
|
|
|
src_nid = cpu_to_node(env->src_cpu);
|
|
dst_nid = cpu_to_node(env->dst_cpu);
|
|
|
|
if (src_nid == dst_nid)
|
|
return -1;
|
|
|
|
/* Migrating away from the preferred node is always bad. */
|
|
if (src_nid == p->numa_preferred_nid) {
|
|
if (env->src_rq->nr_running > env->src_rq->nr_preferred_running)
|
|
return 1;
|
|
else
|
|
return -1;
|
|
}
|
|
|
|
/* Encourage migration to the preferred node. */
|
|
if (dst_nid == p->numa_preferred_nid)
|
|
return 0;
|
|
|
|
/* Leaving a core idle is often worse than degrading locality. */
|
|
if (env->idle == CPU_IDLE)
|
|
return -1;
|
|
|
|
dist = node_distance(src_nid, dst_nid);
|
|
if (numa_group) {
|
|
src_weight = group_weight(p, src_nid, dist);
|
|
dst_weight = group_weight(p, dst_nid, dist);
|
|
} else {
|
|
src_weight = task_weight(p, src_nid, dist);
|
|
dst_weight = task_weight(p, dst_nid, dist);
|
|
}
|
|
|
|
return dst_weight < src_weight;
|
|
}
|
|
|
|
#else
|
|
static inline int migrate_degrades_locality(struct task_struct *p,
|
|
struct lb_env *env)
|
|
{
|
|
return -1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
|
|
*/
|
|
static
|
|
int can_migrate_task(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
int tsk_cache_hot;
|
|
|
|
lockdep_assert_rq_held(env->src_rq);
|
|
|
|
/*
|
|
* We do not migrate tasks that are:
|
|
* 1) throttled_lb_pair, or
|
|
* 2) cannot be migrated to this CPU due to cpus_ptr, or
|
|
* 3) running (obviously), or
|
|
* 4) are cache-hot on their current CPU.
|
|
*/
|
|
if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
|
|
return 0;
|
|
|
|
/* Disregard pcpu kthreads; they are where they need to be. */
|
|
if (kthread_is_per_cpu(p))
|
|
return 0;
|
|
|
|
if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
|
|
int cpu;
|
|
|
|
schedstat_inc(p->stats.nr_failed_migrations_affine);
|
|
|
|
env->flags |= LBF_SOME_PINNED;
|
|
|
|
/*
|
|
* Remember if this task can be migrated to any other CPU in
|
|
* our sched_group. We may want to revisit it if we couldn't
|
|
* meet load balance goals by pulling other tasks on src_cpu.
|
|
*
|
|
* Avoid computing new_dst_cpu
|
|
* - for NEWLY_IDLE
|
|
* - if we have already computed one in current iteration
|
|
* - if it's an active balance
|
|
*/
|
|
if (env->idle == CPU_NEWLY_IDLE ||
|
|
env->flags & (LBF_DST_PINNED | LBF_ACTIVE_LB))
|
|
return 0;
|
|
|
|
/* Prevent to re-select dst_cpu via env's CPUs: */
|
|
for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
|
|
if (cpumask_test_cpu(cpu, p->cpus_ptr)) {
|
|
env->flags |= LBF_DST_PINNED;
|
|
env->new_dst_cpu = cpu;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Record that we found at least one task that could run on dst_cpu */
|
|
env->flags &= ~LBF_ALL_PINNED;
|
|
|
|
if (task_on_cpu(env->src_rq, p)) {
|
|
schedstat_inc(p->stats.nr_failed_migrations_running);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Aggressive migration if:
|
|
* 1) active balance
|
|
* 2) destination numa is preferred
|
|
* 3) task is cache cold, or
|
|
* 4) too many balance attempts have failed.
|
|
*/
|
|
if (env->flags & LBF_ACTIVE_LB)
|
|
return 1;
|
|
|
|
tsk_cache_hot = migrate_degrades_locality(p, env);
|
|
if (tsk_cache_hot == -1)
|
|
tsk_cache_hot = task_hot(p, env);
|
|
|
|
if (tsk_cache_hot <= 0 ||
|
|
env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
|
|
if (tsk_cache_hot == 1) {
|
|
schedstat_inc(env->sd->lb_hot_gained[env->idle]);
|
|
schedstat_inc(p->stats.nr_forced_migrations);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
schedstat_inc(p->stats.nr_failed_migrations_hot);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* detach_task() -- detach the task for the migration specified in env
|
|
*/
|
|
static void detach_task(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
lockdep_assert_rq_held(env->src_rq);
|
|
|
|
deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK);
|
|
set_task_cpu(p, env->dst_cpu);
|
|
}
|
|
|
|
/*
|
|
* detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
|
|
* part of active balancing operations within "domain".
|
|
*
|
|
* Returns a task if successful and NULL otherwise.
|
|
*/
|
|
static struct task_struct *detach_one_task(struct lb_env *env)
|
|
{
|
|
struct task_struct *p;
|
|
|
|
lockdep_assert_rq_held(env->src_rq);
|
|
|
|
list_for_each_entry_reverse(p,
|
|
&env->src_rq->cfs_tasks, se.group_node) {
|
|
if (!can_migrate_task(p, env))
|
|
continue;
|
|
|
|
detach_task(p, env);
|
|
|
|
/*
|
|
* Right now, this is only the second place where
|
|
* lb_gained[env->idle] is updated (other is detach_tasks)
|
|
* so we can safely collect stats here rather than
|
|
* inside detach_tasks().
|
|
*/
|
|
schedstat_inc(env->sd->lb_gained[env->idle]);
|
|
return p;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* detach_tasks() -- tries to detach up to imbalance load/util/tasks from
|
|
* busiest_rq, as part of a balancing operation within domain "sd".
|
|
*
|
|
* Returns number of detached tasks if successful and 0 otherwise.
|
|
*/
|
|
static int detach_tasks(struct lb_env *env)
|
|
{
|
|
struct list_head *tasks = &env->src_rq->cfs_tasks;
|
|
unsigned long util, load;
|
|
struct task_struct *p;
|
|
int detached = 0;
|
|
|
|
lockdep_assert_rq_held(env->src_rq);
|
|
|
|
/*
|
|
* Source run queue has been emptied by another CPU, clear
|
|
* LBF_ALL_PINNED flag as we will not test any task.
|
|
*/
|
|
if (env->src_rq->nr_running <= 1) {
|
|
env->flags &= ~LBF_ALL_PINNED;
|
|
return 0;
|
|
}
|
|
|
|
if (env->imbalance <= 0)
|
|
return 0;
|
|
|
|
while (!list_empty(tasks)) {
|
|
/*
|
|
* We don't want to steal all, otherwise we may be treated likewise,
|
|
* which could at worst lead to a livelock crash.
|
|
*/
|
|
if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1)
|
|
break;
|
|
|
|
env->loop++;
|
|
/*
|
|
* We've more or less seen every task there is, call it quits
|
|
* unless we haven't found any movable task yet.
|
|
*/
|
|
if (env->loop > env->loop_max &&
|
|
!(env->flags & LBF_ALL_PINNED))
|
|
break;
|
|
|
|
/* take a breather every nr_migrate tasks */
|
|
if (env->loop > env->loop_break) {
|
|
env->loop_break += SCHED_NR_MIGRATE_BREAK;
|
|
env->flags |= LBF_NEED_BREAK;
|
|
break;
|
|
}
|
|
|
|
p = list_last_entry(tasks, struct task_struct, se.group_node);
|
|
|
|
if (!can_migrate_task(p, env))
|
|
goto next;
|
|
|
|
switch (env->migration_type) {
|
|
case migrate_load:
|
|
/*
|
|
* Depending of the number of CPUs and tasks and the
|
|
* cgroup hierarchy, task_h_load() can return a null
|
|
* value. Make sure that env->imbalance decreases
|
|
* otherwise detach_tasks() will stop only after
|
|
* detaching up to loop_max tasks.
|
|
*/
|
|
load = max_t(unsigned long, task_h_load(p), 1);
|
|
|
|
if (sched_feat(LB_MIN) &&
|
|
load < 16 && !env->sd->nr_balance_failed)
|
|
goto next;
|
|
|
|
/*
|
|
* Make sure that we don't migrate too much load.
|
|
* Nevertheless, let relax the constraint if
|
|
* scheduler fails to find a good waiting task to
|
|
* migrate.
|
|
*/
|
|
if (shr_bound(load, env->sd->nr_balance_failed) > env->imbalance)
|
|
goto next;
|
|
|
|
env->imbalance -= load;
|
|
break;
|
|
|
|
case migrate_util:
|
|
util = task_util_est(p);
|
|
|
|
if (shr_bound(util, env->sd->nr_balance_failed) > env->imbalance)
|
|
goto next;
|
|
|
|
env->imbalance -= util;
|
|
break;
|
|
|
|
case migrate_task:
|
|
env->imbalance--;
|
|
break;
|
|
|
|
case migrate_misfit:
|
|
/* This is not a misfit task */
|
|
if (task_fits_cpu(p, env->src_cpu))
|
|
goto next;
|
|
|
|
env->imbalance = 0;
|
|
break;
|
|
}
|
|
|
|
detach_task(p, env);
|
|
list_add(&p->se.group_node, &env->tasks);
|
|
|
|
detached++;
|
|
|
|
#ifdef CONFIG_PREEMPTION
|
|
/*
|
|
* NEWIDLE balancing is a source of latency, so preemptible
|
|
* kernels will stop after the first task is detached to minimize
|
|
* the critical section.
|
|
*/
|
|
if (env->idle == CPU_NEWLY_IDLE)
|
|
break;
|
|
#endif
|
|
|
|
/*
|
|
* We only want to steal up to the prescribed amount of
|
|
* load/util/tasks.
|
|
*/
|
|
if (env->imbalance <= 0)
|
|
break;
|
|
|
|
continue;
|
|
next:
|
|
list_move(&p->se.group_node, tasks);
|
|
}
|
|
|
|
/*
|
|
* Right now, this is one of only two places we collect this stat
|
|
* so we can safely collect detach_one_task() stats here rather
|
|
* than inside detach_one_task().
|
|
*/
|
|
schedstat_add(env->sd->lb_gained[env->idle], detached);
|
|
|
|
return detached;
|
|
}
|
|
|
|
/*
|
|
* attach_task() -- attach the task detached by detach_task() to its new rq.
|
|
*/
|
|
static void attach_task(struct rq *rq, struct task_struct *p)
|
|
{
|
|
lockdep_assert_rq_held(rq);
|
|
|
|
WARN_ON_ONCE(task_rq(p) != rq);
|
|
activate_task(rq, p, ENQUEUE_NOCLOCK);
|
|
wakeup_preempt(rq, p, 0);
|
|
}
|
|
|
|
/*
|
|
* attach_one_task() -- attaches the task returned from detach_one_task() to
|
|
* its new rq.
|
|
*/
|
|
static void attach_one_task(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct rq_flags rf;
|
|
|
|
rq_lock(rq, &rf);
|
|
update_rq_clock(rq);
|
|
attach_task(rq, p);
|
|
rq_unlock(rq, &rf);
|
|
}
|
|
|
|
/*
|
|
* attach_tasks() -- attaches all tasks detached by detach_tasks() to their
|
|
* new rq.
|
|
*/
|
|
static void attach_tasks(struct lb_env *env)
|
|
{
|
|
struct list_head *tasks = &env->tasks;
|
|
struct task_struct *p;
|
|
struct rq_flags rf;
|
|
|
|
rq_lock(env->dst_rq, &rf);
|
|
update_rq_clock(env->dst_rq);
|
|
|
|
while (!list_empty(tasks)) {
|
|
p = list_first_entry(tasks, struct task_struct, se.group_node);
|
|
list_del_init(&p->se.group_node);
|
|
|
|
attach_task(env->dst_rq, p);
|
|
}
|
|
|
|
rq_unlock(env->dst_rq, &rf);
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (cfs_rq->avg.load_avg)
|
|
return true;
|
|
|
|
if (cfs_rq->avg.util_avg)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline bool others_have_blocked(struct rq *rq)
|
|
{
|
|
if (cpu_util_rt(rq))
|
|
return true;
|
|
|
|
if (cpu_util_dl(rq))
|
|
return true;
|
|
|
|
if (thermal_load_avg(rq))
|
|
return true;
|
|
|
|
if (cpu_util_irq(rq))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline void update_blocked_load_tick(struct rq *rq)
|
|
{
|
|
WRITE_ONCE(rq->last_blocked_load_update_tick, jiffies);
|
|
}
|
|
|
|
static inline void update_blocked_load_status(struct rq *rq, bool has_blocked)
|
|
{
|
|
if (!has_blocked)
|
|
rq->has_blocked_load = 0;
|
|
}
|
|
#else
|
|
static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) { return false; }
|
|
static inline bool others_have_blocked(struct rq *rq) { return false; }
|
|
static inline void update_blocked_load_tick(struct rq *rq) {}
|
|
static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {}
|
|
#endif
|
|
|
|
static bool __update_blocked_others(struct rq *rq, bool *done)
|
|
{
|
|
const struct sched_class *curr_class;
|
|
u64 now = rq_clock_pelt(rq);
|
|
unsigned long thermal_pressure;
|
|
bool decayed;
|
|
|
|
/*
|
|
* update_load_avg() can call cpufreq_update_util(). Make sure that RT,
|
|
* DL and IRQ signals have been updated before updating CFS.
|
|
*/
|
|
curr_class = rq->curr->sched_class;
|
|
|
|
thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
|
|
|
|
decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
|
|
update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
|
|
update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
|
|
update_irq_load_avg(rq, 0);
|
|
|
|
if (others_have_blocked(rq))
|
|
*done = false;
|
|
|
|
return decayed;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
|
|
static bool __update_blocked_fair(struct rq *rq, bool *done)
|
|
{
|
|
struct cfs_rq *cfs_rq, *pos;
|
|
bool decayed = false;
|
|
int cpu = cpu_of(rq);
|
|
|
|
/*
|
|
* Iterates the task_group tree in a bottom up fashion, see
|
|
* list_add_leaf_cfs_rq() for details.
|
|
*/
|
|
for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) {
|
|
struct sched_entity *se;
|
|
|
|
if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq)) {
|
|
update_tg_load_avg(cfs_rq);
|
|
|
|
if (cfs_rq->nr_running == 0)
|
|
update_idle_cfs_rq_clock_pelt(cfs_rq);
|
|
|
|
if (cfs_rq == &rq->cfs)
|
|
decayed = true;
|
|
}
|
|
|
|
/* Propagate pending load changes to the parent, if any: */
|
|
se = cfs_rq->tg->se[cpu];
|
|
if (se && !skip_blocked_update(se))
|
|
update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
|
|
|
|
/*
|
|
* There can be a lot of idle CPU cgroups. Don't let fully
|
|
* decayed cfs_rqs linger on the list.
|
|
*/
|
|
if (cfs_rq_is_decayed(cfs_rq))
|
|
list_del_leaf_cfs_rq(cfs_rq);
|
|
|
|
/* Don't need periodic decay once load/util_avg are null */
|
|
if (cfs_rq_has_blocked(cfs_rq))
|
|
*done = false;
|
|
}
|
|
|
|
return decayed;
|
|
}
|
|
|
|
/*
|
|
* Compute the hierarchical load factor for cfs_rq and all its ascendants.
|
|
* This needs to be done in a top-down fashion because the load of a child
|
|
* group is a fraction of its parents load.
|
|
*/
|
|
static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
|
|
unsigned long now = jiffies;
|
|
unsigned long load;
|
|
|
|
if (cfs_rq->last_h_load_update == now)
|
|
return;
|
|
|
|
WRITE_ONCE(cfs_rq->h_load_next, NULL);
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
WRITE_ONCE(cfs_rq->h_load_next, se);
|
|
if (cfs_rq->last_h_load_update == now)
|
|
break;
|
|
}
|
|
|
|
if (!se) {
|
|
cfs_rq->h_load = cfs_rq_load_avg(cfs_rq);
|
|
cfs_rq->last_h_load_update = now;
|
|
}
|
|
|
|
while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) {
|
|
load = cfs_rq->h_load;
|
|
load = div64_ul(load * se->avg.load_avg,
|
|
cfs_rq_load_avg(cfs_rq) + 1);
|
|
cfs_rq = group_cfs_rq(se);
|
|
cfs_rq->h_load = load;
|
|
cfs_rq->last_h_load_update = now;
|
|
}
|
|
}
|
|
|
|
static unsigned long task_h_load(struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
|
|
update_cfs_rq_h_load(cfs_rq);
|
|
return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
|
|
cfs_rq_load_avg(cfs_rq) + 1);
|
|
}
|
|
#else
|
|
static bool __update_blocked_fair(struct rq *rq, bool *done)
|
|
{
|
|
struct cfs_rq *cfs_rq = &rq->cfs;
|
|
bool decayed;
|
|
|
|
decayed = update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
|
|
if (cfs_rq_has_blocked(cfs_rq))
|
|
*done = false;
|
|
|
|
return decayed;
|
|
}
|
|
|
|
static unsigned long task_h_load(struct task_struct *p)
|
|
{
|
|
return p->se.avg.load_avg;
|
|
}
|
|
#endif
|
|
|
|
static void update_blocked_averages(int cpu)
|
|
{
|
|
bool decayed = false, done = true;
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct rq_flags rf;
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
update_blocked_load_tick(rq);
|
|
update_rq_clock(rq);
|
|
|
|
decayed |= __update_blocked_others(rq, &done);
|
|
decayed |= __update_blocked_fair(rq, &done);
|
|
|
|
update_blocked_load_status(rq, !done);
|
|
if (decayed)
|
|
cpufreq_update_util(rq, 0);
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
/********** Helpers for find_busiest_group ************************/
|
|
|
|
/*
|
|
* sg_lb_stats - stats of a sched_group required for load_balancing
|
|
*/
|
|
struct sg_lb_stats {
|
|
unsigned long avg_load; /*Avg load across the CPUs of the group */
|
|
unsigned long group_load; /* Total load over the CPUs of the group */
|
|
unsigned long group_capacity;
|
|
unsigned long group_util; /* Total utilization over the CPUs of the group */
|
|
unsigned long group_runnable; /* Total runnable time over the CPUs of the group */
|
|
unsigned int sum_nr_running; /* Nr of tasks running in the group */
|
|
unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */
|
|
unsigned int idle_cpus;
|
|
unsigned int group_weight;
|
|
enum group_type group_type;
|
|
unsigned int group_asym_packing; /* Tasks should be moved to preferred CPU */
|
|
unsigned int group_smt_balance; /* Task on busy SMT be moved */
|
|
unsigned long group_misfit_task_load; /* A CPU has a task too big for its capacity */
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
unsigned int nr_numa_running;
|
|
unsigned int nr_preferred_running;
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* sd_lb_stats - Structure to store the statistics of a sched_domain
|
|
* during load balancing.
|
|
*/
|
|
struct sd_lb_stats {
|
|
struct sched_group *busiest; /* Busiest group in this sd */
|
|
struct sched_group *local; /* Local group in this sd */
|
|
unsigned long total_load; /* Total load of all groups in sd */
|
|
unsigned long total_capacity; /* Total capacity of all groups in sd */
|
|
unsigned long avg_load; /* Average load across all groups in sd */
|
|
unsigned int prefer_sibling; /* tasks should go to sibling first */
|
|
|
|
struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */
|
|
struct sg_lb_stats local_stat; /* Statistics of the local group */
|
|
};
|
|
|
|
static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
|
|
{
|
|
/*
|
|
* Skimp on the clearing to avoid duplicate work. We can avoid clearing
|
|
* local_stat because update_sg_lb_stats() does a full clear/assignment.
|
|
* We must however set busiest_stat::group_type and
|
|
* busiest_stat::idle_cpus to the worst busiest group because
|
|
* update_sd_pick_busiest() reads these before assignment.
|
|
*/
|
|
*sds = (struct sd_lb_stats){
|
|
.busiest = NULL,
|
|
.local = NULL,
|
|
.total_load = 0UL,
|
|
.total_capacity = 0UL,
|
|
.busiest_stat = {
|
|
.idle_cpus = UINT_MAX,
|
|
.group_type = group_has_spare,
|
|
},
|
|
};
|
|
}
|
|
|
|
static unsigned long scale_rt_capacity(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long max = arch_scale_cpu_capacity(cpu);
|
|
unsigned long used, free;
|
|
unsigned long irq;
|
|
|
|
irq = cpu_util_irq(rq);
|
|
|
|
if (unlikely(irq >= max))
|
|
return 1;
|
|
|
|
/*
|
|
* avg_rt.util_avg and avg_dl.util_avg track binary signals
|
|
* (running and not running) with weights 0 and 1024 respectively.
|
|
* avg_thermal.load_avg tracks thermal pressure and the weighted
|
|
* average uses the actual delta max capacity(load).
|
|
*/
|
|
used = cpu_util_rt(rq);
|
|
used += cpu_util_dl(rq);
|
|
used += thermal_load_avg(rq);
|
|
|
|
if (unlikely(used >= max))
|
|
return 1;
|
|
|
|
free = max - used;
|
|
|
|
return scale_irq_capacity(free, irq, max);
|
|
}
|
|
|
|
static void update_cpu_capacity(struct sched_domain *sd, int cpu)
|
|
{
|
|
unsigned long capacity = scale_rt_capacity(cpu);
|
|
struct sched_group *sdg = sd->groups;
|
|
|
|
if (!capacity)
|
|
capacity = 1;
|
|
|
|
cpu_rq(cpu)->cpu_capacity = capacity;
|
|
trace_sched_cpu_capacity_tp(cpu_rq(cpu));
|
|
|
|
sdg->sgc->capacity = capacity;
|
|
sdg->sgc->min_capacity = capacity;
|
|
sdg->sgc->max_capacity = capacity;
|
|
}
|
|
|
|
void update_group_capacity(struct sched_domain *sd, int cpu)
|
|
{
|
|
struct sched_domain *child = sd->child;
|
|
struct sched_group *group, *sdg = sd->groups;
|
|
unsigned long capacity, min_capacity, max_capacity;
|
|
unsigned long interval;
|
|
|
|
interval = msecs_to_jiffies(sd->balance_interval);
|
|
interval = clamp(interval, 1UL, max_load_balance_interval);
|
|
sdg->sgc->next_update = jiffies + interval;
|
|
|
|
if (!child) {
|
|
update_cpu_capacity(sd, cpu);
|
|
return;
|
|
}
|
|
|
|
capacity = 0;
|
|
min_capacity = ULONG_MAX;
|
|
max_capacity = 0;
|
|
|
|
if (child->flags & SD_OVERLAP) {
|
|
/*
|
|
* SD_OVERLAP domains cannot assume that child groups
|
|
* span the current group.
|
|
*/
|
|
|
|
for_each_cpu(cpu, sched_group_span(sdg)) {
|
|
unsigned long cpu_cap = capacity_of(cpu);
|
|
|
|
capacity += cpu_cap;
|
|
min_capacity = min(cpu_cap, min_capacity);
|
|
max_capacity = max(cpu_cap, max_capacity);
|
|
}
|
|
} else {
|
|
/*
|
|
* !SD_OVERLAP domains can assume that child groups
|
|
* span the current group.
|
|
*/
|
|
|
|
group = child->groups;
|
|
do {
|
|
struct sched_group_capacity *sgc = group->sgc;
|
|
|
|
capacity += sgc->capacity;
|
|
min_capacity = min(sgc->min_capacity, min_capacity);
|
|
max_capacity = max(sgc->max_capacity, max_capacity);
|
|
group = group->next;
|
|
} while (group != child->groups);
|
|
}
|
|
|
|
sdg->sgc->capacity = capacity;
|
|
sdg->sgc->min_capacity = min_capacity;
|
|
sdg->sgc->max_capacity = max_capacity;
|
|
}
|
|
|
|
/*
|
|
* Check whether the capacity of the rq has been noticeably reduced by side
|
|
* activity. The imbalance_pct is used for the threshold.
|
|
* Return true is the capacity is reduced
|
|
*/
|
|
static inline int
|
|
check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
|
|
{
|
|
return ((rq->cpu_capacity * sd->imbalance_pct) <
|
|
(arch_scale_cpu_capacity(cpu_of(rq)) * 100));
|
|
}
|
|
|
|
/*
|
|
* Check whether a rq has a misfit task and if it looks like we can actually
|
|
* help that task: we can migrate the task to a CPU of higher capacity, or
|
|
* the task's current CPU is heavily pressured.
|
|
*/
|
|
static inline int check_misfit_status(struct rq *rq, struct sched_domain *sd)
|
|
{
|
|
return rq->misfit_task_load &&
|
|
(arch_scale_cpu_capacity(rq->cpu) < rq->rd->max_cpu_capacity ||
|
|
check_cpu_capacity(rq, sd));
|
|
}
|
|
|
|
/*
|
|
* Group imbalance indicates (and tries to solve) the problem where balancing
|
|
* groups is inadequate due to ->cpus_ptr constraints.
|
|
*
|
|
* Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
|
|
* cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
|
|
* Something like:
|
|
*
|
|
* { 0 1 2 3 } { 4 5 6 7 }
|
|
* * * * *
|
|
*
|
|
* If we were to balance group-wise we'd place two tasks in the first group and
|
|
* two tasks in the second group. Clearly this is undesired as it will overload
|
|
* cpu 3 and leave one of the CPUs in the second group unused.
|
|
*
|
|
* The current solution to this issue is detecting the skew in the first group
|
|
* by noticing the lower domain failed to reach balance and had difficulty
|
|
* moving tasks due to affinity constraints.
|
|
*
|
|
* When this is so detected; this group becomes a candidate for busiest; see
|
|
* update_sd_pick_busiest(). And calculate_imbalance() and
|
|
* find_busiest_group() avoid some of the usual balance conditions to allow it
|
|
* to create an effective group imbalance.
|
|
*
|
|
* This is a somewhat tricky proposition since the next run might not find the
|
|
* group imbalance and decide the groups need to be balanced again. A most
|
|
* subtle and fragile situation.
|
|
*/
|
|
|
|
static inline int sg_imbalanced(struct sched_group *group)
|
|
{
|
|
return group->sgc->imbalance;
|
|
}
|
|
|
|
/*
|
|
* group_has_capacity returns true if the group has spare capacity that could
|
|
* be used by some tasks.
|
|
* We consider that a group has spare capacity if the number of task is
|
|
* smaller than the number of CPUs or if the utilization is lower than the
|
|
* available capacity for CFS tasks.
|
|
* For the latter, we use a threshold to stabilize the state, to take into
|
|
* account the variance of the tasks' load and to return true if the available
|
|
* capacity in meaningful for the load balancer.
|
|
* As an example, an available capacity of 1% can appear but it doesn't make
|
|
* any benefit for the load balance.
|
|
*/
|
|
static inline bool
|
|
group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
|
|
{
|
|
if (sgs->sum_nr_running < sgs->group_weight)
|
|
return true;
|
|
|
|
if ((sgs->group_capacity * imbalance_pct) <
|
|
(sgs->group_runnable * 100))
|
|
return false;
|
|
|
|
if ((sgs->group_capacity * 100) >
|
|
(sgs->group_util * imbalance_pct))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* group_is_overloaded returns true if the group has more tasks than it can
|
|
* handle.
|
|
* group_is_overloaded is not equals to !group_has_capacity because a group
|
|
* with the exact right number of tasks, has no more spare capacity but is not
|
|
* overloaded so both group_has_capacity and group_is_overloaded return
|
|
* false.
|
|
*/
|
|
static inline bool
|
|
group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
|
|
{
|
|
if (sgs->sum_nr_running <= sgs->group_weight)
|
|
return false;
|
|
|
|
if ((sgs->group_capacity * 100) <
|
|
(sgs->group_util * imbalance_pct))
|
|
return true;
|
|
|
|
if ((sgs->group_capacity * imbalance_pct) <
|
|
(sgs->group_runnable * 100))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline enum
|
|
group_type group_classify(unsigned int imbalance_pct,
|
|
struct sched_group *group,
|
|
struct sg_lb_stats *sgs)
|
|
{
|
|
if (group_is_overloaded(imbalance_pct, sgs))
|
|
return group_overloaded;
|
|
|
|
if (sg_imbalanced(group))
|
|
return group_imbalanced;
|
|
|
|
if (sgs->group_asym_packing)
|
|
return group_asym_packing;
|
|
|
|
if (sgs->group_smt_balance)
|
|
return group_smt_balance;
|
|
|
|
if (sgs->group_misfit_task_load)
|
|
return group_misfit_task;
|
|
|
|
if (!group_has_capacity(imbalance_pct, sgs))
|
|
return group_fully_busy;
|
|
|
|
return group_has_spare;
|
|
}
|
|
|
|
/**
|
|
* sched_use_asym_prio - Check whether asym_packing priority must be used
|
|
* @sd: The scheduling domain of the load balancing
|
|
* @cpu: A CPU
|
|
*
|
|
* Always use CPU priority when balancing load between SMT siblings. When
|
|
* balancing load between cores, it is not sufficient that @cpu is idle. Only
|
|
* use CPU priority if the whole core is idle.
|
|
*
|
|
* Returns: True if the priority of @cpu must be followed. False otherwise.
|
|
*/
|
|
static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
|
|
{
|
|
if (!(sd->flags & SD_ASYM_PACKING))
|
|
return false;
|
|
|
|
if (!sched_smt_active())
|
|
return true;
|
|
|
|
return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
|
|
}
|
|
|
|
static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
|
|
{
|
|
/*
|
|
* First check if @dst_cpu can do asym_packing load balance. Only do it
|
|
* if it has higher priority than @src_cpu.
|
|
*/
|
|
return sched_use_asym_prio(sd, dst_cpu) &&
|
|
sched_asym_prefer(dst_cpu, src_cpu);
|
|
}
|
|
|
|
/**
|
|
* sched_group_asym - Check if the destination CPU can do asym_packing balance
|
|
* @env: The load balancing environment
|
|
* @sgs: Load-balancing statistics of the candidate busiest group
|
|
* @group: The candidate busiest group
|
|
*
|
|
* @env::dst_cpu can do asym_packing if it has higher priority than the
|
|
* preferred CPU of @group.
|
|
*
|
|
* Return: true if @env::dst_cpu can do with asym_packing load balance. False
|
|
* otherwise.
|
|
*/
|
|
static inline bool
|
|
sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
|
|
{
|
|
/*
|
|
* CPU priorities do not make sense for SMT cores with more than one
|
|
* busy sibling.
|
|
*/
|
|
if ((group->flags & SD_SHARE_CPUCAPACITY) &&
|
|
(sgs->group_weight - sgs->idle_cpus != 1))
|
|
return false;
|
|
|
|
return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
|
|
}
|
|
|
|
/* One group has more than one SMT CPU while the other group does not */
|
|
static inline bool smt_vs_nonsmt_groups(struct sched_group *sg1,
|
|
struct sched_group *sg2)
|
|
{
|
|
if (!sg1 || !sg2)
|
|
return false;
|
|
|
|
return (sg1->flags & SD_SHARE_CPUCAPACITY) !=
|
|
(sg2->flags & SD_SHARE_CPUCAPACITY);
|
|
}
|
|
|
|
static inline bool smt_balance(struct lb_env *env, struct sg_lb_stats *sgs,
|
|
struct sched_group *group)
|
|
{
|
|
if (env->idle == CPU_NOT_IDLE)
|
|
return false;
|
|
|
|
/*
|
|
* For SMT source group, it is better to move a task
|
|
* to a CPU that doesn't have multiple tasks sharing its CPU capacity.
|
|
* Note that if a group has a single SMT, SD_SHARE_CPUCAPACITY
|
|
* will not be on.
|
|
*/
|
|
if (group->flags & SD_SHARE_CPUCAPACITY &&
|
|
sgs->sum_h_nr_running > 1)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline long sibling_imbalance(struct lb_env *env,
|
|
struct sd_lb_stats *sds,
|
|
struct sg_lb_stats *busiest,
|
|
struct sg_lb_stats *local)
|
|
{
|
|
int ncores_busiest, ncores_local;
|
|
long imbalance;
|
|
|
|
if (env->idle == CPU_NOT_IDLE || !busiest->sum_nr_running)
|
|
return 0;
|
|
|
|
ncores_busiest = sds->busiest->cores;
|
|
ncores_local = sds->local->cores;
|
|
|
|
if (ncores_busiest == ncores_local) {
|
|
imbalance = busiest->sum_nr_running;
|
|
lsub_positive(&imbalance, local->sum_nr_running);
|
|
return imbalance;
|
|
}
|
|
|
|
/* Balance such that nr_running/ncores ratio are same on both groups */
|
|
imbalance = ncores_local * busiest->sum_nr_running;
|
|
lsub_positive(&imbalance, ncores_busiest * local->sum_nr_running);
|
|
/* Normalize imbalance and do rounding on normalization */
|
|
imbalance = 2 * imbalance + ncores_local + ncores_busiest;
|
|
imbalance /= ncores_local + ncores_busiest;
|
|
|
|
/* Take advantage of resource in an empty sched group */
|
|
if (imbalance <= 1 && local->sum_nr_running == 0 &&
|
|
busiest->sum_nr_running > 1)
|
|
imbalance = 2;
|
|
|
|
return imbalance;
|
|
}
|
|
|
|
static inline bool
|
|
sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
|
|
{
|
|
/*
|
|
* When there is more than 1 task, the group_overloaded case already
|
|
* takes care of cpu with reduced capacity
|
|
*/
|
|
if (rq->cfs.h_nr_running != 1)
|
|
return false;
|
|
|
|
return check_cpu_capacity(rq, sd);
|
|
}
|
|
|
|
/**
|
|
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
|
|
* @env: The load balancing environment.
|
|
* @sds: Load-balancing data with statistics of the local group.
|
|
* @group: sched_group whose statistics are to be updated.
|
|
* @sgs: variable to hold the statistics for this group.
|
|
* @sg_status: Holds flag indicating the status of the sched_group
|
|
*/
|
|
static inline void update_sg_lb_stats(struct lb_env *env,
|
|
struct sd_lb_stats *sds,
|
|
struct sched_group *group,
|
|
struct sg_lb_stats *sgs,
|
|
int *sg_status)
|
|
{
|
|
int i, nr_running, local_group;
|
|
|
|
memset(sgs, 0, sizeof(*sgs));
|
|
|
|
local_group = group == sds->local;
|
|
|
|
for_each_cpu_and(i, sched_group_span(group), env->cpus) {
|
|
struct rq *rq = cpu_rq(i);
|
|
unsigned long load = cpu_load(rq);
|
|
|
|
sgs->group_load += load;
|
|
sgs->group_util += cpu_util_cfs(i);
|
|
sgs->group_runnable += cpu_runnable(rq);
|
|
sgs->sum_h_nr_running += rq->cfs.h_nr_running;
|
|
|
|
nr_running = rq->nr_running;
|
|
sgs->sum_nr_running += nr_running;
|
|
|
|
if (nr_running > 1)
|
|
*sg_status |= SG_OVERLOAD;
|
|
|
|
if (cpu_overutilized(i))
|
|
*sg_status |= SG_OVERUTILIZED;
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
sgs->nr_numa_running += rq->nr_numa_running;
|
|
sgs->nr_preferred_running += rq->nr_preferred_running;
|
|
#endif
|
|
/*
|
|
* No need to call idle_cpu() if nr_running is not 0
|
|
*/
|
|
if (!nr_running && idle_cpu(i)) {
|
|
sgs->idle_cpus++;
|
|
/* Idle cpu can't have misfit task */
|
|
continue;
|
|
}
|
|
|
|
if (local_group)
|
|
continue;
|
|
|
|
if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
|
|
/* Check for a misfit task on the cpu */
|
|
if (sgs->group_misfit_task_load < rq->misfit_task_load) {
|
|
sgs->group_misfit_task_load = rq->misfit_task_load;
|
|
*sg_status |= SG_OVERLOAD;
|
|
}
|
|
} else if ((env->idle != CPU_NOT_IDLE) &&
|
|
sched_reduced_capacity(rq, env->sd)) {
|
|
/* Check for a task running on a CPU with reduced capacity */
|
|
if (sgs->group_misfit_task_load < load)
|
|
sgs->group_misfit_task_load = load;
|
|
}
|
|
}
|
|
|
|
sgs->group_capacity = group->sgc->capacity;
|
|
|
|
sgs->group_weight = group->group_weight;
|
|
|
|
/* Check if dst CPU is idle and preferred to this group */
|
|
if (!local_group && env->idle != CPU_NOT_IDLE && sgs->sum_h_nr_running &&
|
|
sched_group_asym(env, sgs, group))
|
|
sgs->group_asym_packing = 1;
|
|
|
|
/* Check for loaded SMT group to be balanced to dst CPU */
|
|
if (!local_group && smt_balance(env, sgs, group))
|
|
sgs->group_smt_balance = 1;
|
|
|
|
sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
|
|
|
|
/* Computing avg_load makes sense only when group is overloaded */
|
|
if (sgs->group_type == group_overloaded)
|
|
sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
|
|
sgs->group_capacity;
|
|
}
|
|
|
|
/**
|
|
* update_sd_pick_busiest - return 1 on busiest group
|
|
* @env: The load balancing environment.
|
|
* @sds: sched_domain statistics
|
|
* @sg: sched_group candidate to be checked for being the busiest
|
|
* @sgs: sched_group statistics
|
|
*
|
|
* Determine if @sg is a busier group than the previously selected
|
|
* busiest group.
|
|
*
|
|
* Return: %true if @sg is a busier group than the previously selected
|
|
* busiest group. %false otherwise.
|
|
*/
|
|
static bool update_sd_pick_busiest(struct lb_env *env,
|
|
struct sd_lb_stats *sds,
|
|
struct sched_group *sg,
|
|
struct sg_lb_stats *sgs)
|
|
{
|
|
struct sg_lb_stats *busiest = &sds->busiest_stat;
|
|
|
|
/* Make sure that there is at least one task to pull */
|
|
if (!sgs->sum_h_nr_running)
|
|
return false;
|
|
|
|
/*
|
|
* Don't try to pull misfit tasks we can't help.
|
|
* We can use max_capacity here as reduction in capacity on some
|
|
* CPUs in the group should either be possible to resolve
|
|
* internally or be covered by avg_load imbalance (eventually).
|
|
*/
|
|
if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
|
|
(sgs->group_type == group_misfit_task) &&
|
|
(!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
|
|
sds->local_stat.group_type != group_has_spare))
|
|
return false;
|
|
|
|
if (sgs->group_type > busiest->group_type)
|
|
return true;
|
|
|
|
if (sgs->group_type < busiest->group_type)
|
|
return false;
|
|
|
|
/*
|
|
* The candidate and the current busiest group are the same type of
|
|
* group. Let check which one is the busiest according to the type.
|
|
*/
|
|
|
|
switch (sgs->group_type) {
|
|
case group_overloaded:
|
|
/* Select the overloaded group with highest avg_load. */
|
|
return sgs->avg_load > busiest->avg_load;
|
|
|
|
case group_imbalanced:
|
|
/*
|
|
* Select the 1st imbalanced group as we don't have any way to
|
|
* choose one more than another.
|
|
*/
|
|
return false;
|
|
|
|
case group_asym_packing:
|
|
/* Prefer to move from lowest priority CPU's work */
|
|
return sched_asym_prefer(sds->busiest->asym_prefer_cpu, sg->asym_prefer_cpu);
|
|
|
|
case group_misfit_task:
|
|
/*
|
|
* If we have more than one misfit sg go with the biggest
|
|
* misfit.
|
|
*/
|
|
return sgs->group_misfit_task_load > busiest->group_misfit_task_load;
|
|
|
|
case group_smt_balance:
|
|
/*
|
|
* Check if we have spare CPUs on either SMT group to
|
|
* choose has spare or fully busy handling.
|
|
*/
|
|
if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0)
|
|
goto has_spare;
|
|
|
|
fallthrough;
|
|
|
|
case group_fully_busy:
|
|
/*
|
|
* Select the fully busy group with highest avg_load. In
|
|
* theory, there is no need to pull task from such kind of
|
|
* group because tasks have all compute capacity that they need
|
|
* but we can still improve the overall throughput by reducing
|
|
* contention when accessing shared HW resources.
|
|
*
|
|
* XXX for now avg_load is not computed and always 0 so we
|
|
* select the 1st one, except if @sg is composed of SMT
|
|
* siblings.
|
|
*/
|
|
|
|
if (sgs->avg_load < busiest->avg_load)
|
|
return false;
|
|
|
|
if (sgs->avg_load == busiest->avg_load) {
|
|
/*
|
|
* SMT sched groups need more help than non-SMT groups.
|
|
* If @sg happens to also be SMT, either choice is good.
|
|
*/
|
|
if (sds->busiest->flags & SD_SHARE_CPUCAPACITY)
|
|
return false;
|
|
}
|
|
|
|
break;
|
|
|
|
case group_has_spare:
|
|
/*
|
|
* Do not pick sg with SMT CPUs over sg with pure CPUs,
|
|
* as we do not want to pull task off SMT core with one task
|
|
* and make the core idle.
|
|
*/
|
|
if (smt_vs_nonsmt_groups(sds->busiest, sg)) {
|
|
if (sg->flags & SD_SHARE_CPUCAPACITY && sgs->sum_h_nr_running <= 1)
|
|
return false;
|
|
else
|
|
return true;
|
|
}
|
|
has_spare:
|
|
|
|
/*
|
|
* Select not overloaded group with lowest number of idle cpus
|
|
* and highest number of running tasks. We could also compare
|
|
* the spare capacity which is more stable but it can end up
|
|
* that the group has less spare capacity but finally more idle
|
|
* CPUs which means less opportunity to pull tasks.
|
|
*/
|
|
if (sgs->idle_cpus > busiest->idle_cpus)
|
|
return false;
|
|
else if ((sgs->idle_cpus == busiest->idle_cpus) &&
|
|
(sgs->sum_nr_running <= busiest->sum_nr_running))
|
|
return false;
|
|
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Candidate sg has no more than one task per CPU and has higher
|
|
* per-CPU capacity. Migrating tasks to less capable CPUs may harm
|
|
* throughput. Maximize throughput, power/energy consequences are not
|
|
* considered.
|
|
*/
|
|
if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
|
|
(sgs->group_type <= group_fully_busy) &&
|
|
(capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu))))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
|
|
{
|
|
if (sgs->sum_h_nr_running > sgs->nr_numa_running)
|
|
return regular;
|
|
if (sgs->sum_h_nr_running > sgs->nr_preferred_running)
|
|
return remote;
|
|
return all;
|
|
}
|
|
|
|
static inline enum fbq_type fbq_classify_rq(struct rq *rq)
|
|
{
|
|
if (rq->nr_running > rq->nr_numa_running)
|
|
return regular;
|
|
if (rq->nr_running > rq->nr_preferred_running)
|
|
return remote;
|
|
return all;
|
|
}
|
|
#else
|
|
static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
|
|
{
|
|
return all;
|
|
}
|
|
|
|
static inline enum fbq_type fbq_classify_rq(struct rq *rq)
|
|
{
|
|
return regular;
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
|
|
struct sg_lb_stats;
|
|
|
|
/*
|
|
* task_running_on_cpu - return 1 if @p is running on @cpu.
|
|
*/
|
|
|
|
static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
|
|
{
|
|
/* Task has no contribution or is new */
|
|
if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
|
|
return 0;
|
|
|
|
if (task_on_rq_queued(p))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* idle_cpu_without - would a given CPU be idle without p ?
|
|
* @cpu: the processor on which idleness is tested.
|
|
* @p: task which should be ignored.
|
|
*
|
|
* Return: 1 if the CPU would be idle. 0 otherwise.
|
|
*/
|
|
static int idle_cpu_without(int cpu, struct task_struct *p)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (rq->curr != rq->idle && rq->curr != p)
|
|
return 0;
|
|
|
|
/*
|
|
* rq->nr_running can't be used but an updated version without the
|
|
* impact of p on cpu must be used instead. The updated nr_running
|
|
* be computed and tested before calling idle_cpu_without().
|
|
*/
|
|
|
|
if (rq->ttwu_pending)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* update_sg_wakeup_stats - Update sched_group's statistics for wakeup.
|
|
* @sd: The sched_domain level to look for idlest group.
|
|
* @group: sched_group whose statistics are to be updated.
|
|
* @sgs: variable to hold the statistics for this group.
|
|
* @p: The task for which we look for the idlest group/CPU.
|
|
*/
|
|
static inline void update_sg_wakeup_stats(struct sched_domain *sd,
|
|
struct sched_group *group,
|
|
struct sg_lb_stats *sgs,
|
|
struct task_struct *p)
|
|
{
|
|
int i, nr_running;
|
|
|
|
memset(sgs, 0, sizeof(*sgs));
|
|
|
|
/* Assume that task can't fit any CPU of the group */
|
|
if (sd->flags & SD_ASYM_CPUCAPACITY)
|
|
sgs->group_misfit_task_load = 1;
|
|
|
|
for_each_cpu(i, sched_group_span(group)) {
|
|
struct rq *rq = cpu_rq(i);
|
|
unsigned int local;
|
|
|
|
sgs->group_load += cpu_load_without(rq, p);
|
|
sgs->group_util += cpu_util_without(i, p);
|
|
sgs->group_runnable += cpu_runnable_without(rq, p);
|
|
local = task_running_on_cpu(i, p);
|
|
sgs->sum_h_nr_running += rq->cfs.h_nr_running - local;
|
|
|
|
nr_running = rq->nr_running - local;
|
|
sgs->sum_nr_running += nr_running;
|
|
|
|
/*
|
|
* No need to call idle_cpu_without() if nr_running is not 0
|
|
*/
|
|
if (!nr_running && idle_cpu_without(i, p))
|
|
sgs->idle_cpus++;
|
|
|
|
/* Check if task fits in the CPU */
|
|
if (sd->flags & SD_ASYM_CPUCAPACITY &&
|
|
sgs->group_misfit_task_load &&
|
|
task_fits_cpu(p, i))
|
|
sgs->group_misfit_task_load = 0;
|
|
|
|
}
|
|
|
|
sgs->group_capacity = group->sgc->capacity;
|
|
|
|
sgs->group_weight = group->group_weight;
|
|
|
|
sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
|
|
|
|
/*
|
|
* Computing avg_load makes sense only when group is fully busy or
|
|
* overloaded
|
|
*/
|
|
if (sgs->group_type == group_fully_busy ||
|
|
sgs->group_type == group_overloaded)
|
|
sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
|
|
sgs->group_capacity;
|
|
}
|
|
|
|
static bool update_pick_idlest(struct sched_group *idlest,
|
|
struct sg_lb_stats *idlest_sgs,
|
|
struct sched_group *group,
|
|
struct sg_lb_stats *sgs)
|
|
{
|
|
if (sgs->group_type < idlest_sgs->group_type)
|
|
return true;
|
|
|
|
if (sgs->group_type > idlest_sgs->group_type)
|
|
return false;
|
|
|
|
/*
|
|
* The candidate and the current idlest group are the same type of
|
|
* group. Let check which one is the idlest according to the type.
|
|
*/
|
|
|
|
switch (sgs->group_type) {
|
|
case group_overloaded:
|
|
case group_fully_busy:
|
|
/* Select the group with lowest avg_load. */
|
|
if (idlest_sgs->avg_load <= sgs->avg_load)
|
|
return false;
|
|
break;
|
|
|
|
case group_imbalanced:
|
|
case group_asym_packing:
|
|
case group_smt_balance:
|
|
/* Those types are not used in the slow wakeup path */
|
|
return false;
|
|
|
|
case group_misfit_task:
|
|
/* Select group with the highest max capacity */
|
|
if (idlest->sgc->max_capacity >= group->sgc->max_capacity)
|
|
return false;
|
|
break;
|
|
|
|
case group_has_spare:
|
|
/* Select group with most idle CPUs */
|
|
if (idlest_sgs->idle_cpus > sgs->idle_cpus)
|
|
return false;
|
|
|
|
/* Select group with lowest group_util */
|
|
if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
|
|
idlest_sgs->group_util <= sgs->group_util)
|
|
return false;
|
|
|
|
break;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* find_idlest_group() finds and returns the least busy CPU group within the
|
|
* domain.
|
|
*
|
|
* Assumes p is allowed on at least one CPU in sd.
|
|
*/
|
|
static struct sched_group *
|
|
find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
|
|
{
|
|
struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
|
|
struct sg_lb_stats local_sgs, tmp_sgs;
|
|
struct sg_lb_stats *sgs;
|
|
unsigned long imbalance;
|
|
struct sg_lb_stats idlest_sgs = {
|
|
.avg_load = UINT_MAX,
|
|
.group_type = group_overloaded,
|
|
};
|
|
|
|
do {
|
|
int local_group;
|
|
|
|
/* Skip over this group if it has no CPUs allowed */
|
|
if (!cpumask_intersects(sched_group_span(group),
|
|
p->cpus_ptr))
|
|
continue;
|
|
|
|
/* Skip over this group if no cookie matched */
|
|
if (!sched_group_cookie_match(cpu_rq(this_cpu), p, group))
|
|
continue;
|
|
|
|
local_group = cpumask_test_cpu(this_cpu,
|
|
sched_group_span(group));
|
|
|
|
if (local_group) {
|
|
sgs = &local_sgs;
|
|
local = group;
|
|
} else {
|
|
sgs = &tmp_sgs;
|
|
}
|
|
|
|
update_sg_wakeup_stats(sd, group, sgs, p);
|
|
|
|
if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs)) {
|
|
idlest = group;
|
|
idlest_sgs = *sgs;
|
|
}
|
|
|
|
} while (group = group->next, group != sd->groups);
|
|
|
|
|
|
/* There is no idlest group to push tasks to */
|
|
if (!idlest)
|
|
return NULL;
|
|
|
|
/* The local group has been skipped because of CPU affinity */
|
|
if (!local)
|
|
return idlest;
|
|
|
|
/*
|
|
* If the local group is idler than the selected idlest group
|
|
* don't try and push the task.
|
|
*/
|
|
if (local_sgs.group_type < idlest_sgs.group_type)
|
|
return NULL;
|
|
|
|
/*
|
|
* If the local group is busier than the selected idlest group
|
|
* try and push the task.
|
|
*/
|
|
if (local_sgs.group_type > idlest_sgs.group_type)
|
|
return idlest;
|
|
|
|
switch (local_sgs.group_type) {
|
|
case group_overloaded:
|
|
case group_fully_busy:
|
|
|
|
/* Calculate allowed imbalance based on load */
|
|
imbalance = scale_load_down(NICE_0_LOAD) *
|
|
(sd->imbalance_pct-100) / 100;
|
|
|
|
/*
|
|
* When comparing groups across NUMA domains, it's possible for
|
|
* the local domain to be very lightly loaded relative to the
|
|
* remote domains but "imbalance" skews the comparison making
|
|
* remote CPUs look much more favourable. When considering
|
|
* cross-domain, add imbalance to the load on the remote node
|
|
* and consider staying local.
|
|
*/
|
|
|
|
if ((sd->flags & SD_NUMA) &&
|
|
((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
|
|
return NULL;
|
|
|
|
/*
|
|
* If the local group is less loaded than the selected
|
|
* idlest group don't try and push any tasks.
|
|
*/
|
|
if (idlest_sgs.avg_load >= (local_sgs.avg_load + imbalance))
|
|
return NULL;
|
|
|
|
if (100 * local_sgs.avg_load <= sd->imbalance_pct * idlest_sgs.avg_load)
|
|
return NULL;
|
|
break;
|
|
|
|
case group_imbalanced:
|
|
case group_asym_packing:
|
|
case group_smt_balance:
|
|
/* Those type are not used in the slow wakeup path */
|
|
return NULL;
|
|
|
|
case group_misfit_task:
|
|
/* Select group with the highest max capacity */
|
|
if (local->sgc->max_capacity >= idlest->sgc->max_capacity)
|
|
return NULL;
|
|
break;
|
|
|
|
case group_has_spare:
|
|
#ifdef CONFIG_NUMA
|
|
if (sd->flags & SD_NUMA) {
|
|
int imb_numa_nr = sd->imb_numa_nr;
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
int idlest_cpu;
|
|
/*
|
|
* If there is spare capacity at NUMA, try to select
|
|
* the preferred node
|
|
*/
|
|
if (cpu_to_node(this_cpu) == p->numa_preferred_nid)
|
|
return NULL;
|
|
|
|
idlest_cpu = cpumask_first(sched_group_span(idlest));
|
|
if (cpu_to_node(idlest_cpu) == p->numa_preferred_nid)
|
|
return idlest;
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
/*
|
|
* Otherwise, keep the task close to the wakeup source
|
|
* and improve locality if the number of running tasks
|
|
* would remain below threshold where an imbalance is
|
|
* allowed while accounting for the possibility the
|
|
* task is pinned to a subset of CPUs. If there is a
|
|
* real need of migration, periodic load balance will
|
|
* take care of it.
|
|
*/
|
|
if (p->nr_cpus_allowed != NR_CPUS) {
|
|
struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
|
|
|
|
cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
|
|
imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
|
|
}
|
|
|
|
imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);
|
|
if (!adjust_numa_imbalance(imbalance,
|
|
local_sgs.sum_nr_running + 1,
|
|
imb_numa_nr)) {
|
|
return NULL;
|
|
}
|
|
}
|
|
#endif /* CONFIG_NUMA */
|
|
|
|
/*
|
|
* Select group with highest number of idle CPUs. We could also
|
|
* compare the utilization which is more stable but it can end
|
|
* up that the group has less spare capacity but finally more
|
|
* idle CPUs which means more opportunity to run task.
|
|
*/
|
|
if (local_sgs.idle_cpus >= idlest_sgs.idle_cpus)
|
|
return NULL;
|
|
break;
|
|
}
|
|
|
|
return idlest;
|
|
}
|
|
|
|
static void update_idle_cpu_scan(struct lb_env *env,
|
|
unsigned long sum_util)
|
|
{
|
|
struct sched_domain_shared *sd_share;
|
|
int llc_weight, pct;
|
|
u64 x, y, tmp;
|
|
/*
|
|
* Update the number of CPUs to scan in LLC domain, which could
|
|
* be used as a hint in select_idle_cpu(). The update of sd_share
|
|
* could be expensive because it is within a shared cache line.
|
|
* So the write of this hint only occurs during periodic load
|
|
* balancing, rather than CPU_NEWLY_IDLE, because the latter
|
|
* can fire way more frequently than the former.
|
|
*/
|
|
if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)
|
|
return;
|
|
|
|
llc_weight = per_cpu(sd_llc_size, env->dst_cpu);
|
|
if (env->sd->span_weight != llc_weight)
|
|
return;
|
|
|
|
sd_share = rcu_dereference(per_cpu(sd_llc_shared, env->dst_cpu));
|
|
if (!sd_share)
|
|
return;
|
|
|
|
/*
|
|
* The number of CPUs to search drops as sum_util increases, when
|
|
* sum_util hits 85% or above, the scan stops.
|
|
* The reason to choose 85% as the threshold is because this is the
|
|
* imbalance_pct(117) when a LLC sched group is overloaded.
|
|
*
|
|
* let y = SCHED_CAPACITY_SCALE - p * x^2 [1]
|
|
* and y'= y / SCHED_CAPACITY_SCALE
|
|
*
|
|
* x is the ratio of sum_util compared to the CPU capacity:
|
|
* x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
|
|
* y' is the ratio of CPUs to be scanned in the LLC domain,
|
|
* and the number of CPUs to scan is calculated by:
|
|
*
|
|
* nr_scan = llc_weight * y' [2]
|
|
*
|
|
* When x hits the threshold of overloaded, AKA, when
|
|
* x = 100 / pct, y drops to 0. According to [1],
|
|
* p should be SCHED_CAPACITY_SCALE * pct^2 / 10000
|
|
*
|
|
* Scale x by SCHED_CAPACITY_SCALE:
|
|
* x' = sum_util / llc_weight; [3]
|
|
*
|
|
* and finally [1] becomes:
|
|
* y = SCHED_CAPACITY_SCALE -
|
|
* x'^2 * pct^2 / (10000 * SCHED_CAPACITY_SCALE) [4]
|
|
*
|
|
*/
|
|
/* equation [3] */
|
|
x = sum_util;
|
|
do_div(x, llc_weight);
|
|
|
|
/* equation [4] */
|
|
pct = env->sd->imbalance_pct;
|
|
tmp = x * x * pct * pct;
|
|
do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);
|
|
tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);
|
|
y = SCHED_CAPACITY_SCALE - tmp;
|
|
|
|
/* equation [2] */
|
|
y *= llc_weight;
|
|
do_div(y, SCHED_CAPACITY_SCALE);
|
|
if ((int)y != sd_share->nr_idle_scan)
|
|
WRITE_ONCE(sd_share->nr_idle_scan, (int)y);
|
|
}
|
|
|
|
/**
|
|
* update_sd_lb_stats - Update sched_domain's statistics for load balancing.
|
|
* @env: The load balancing environment.
|
|
* @sds: variable to hold the statistics for this sched_domain.
|
|
*/
|
|
|
|
static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
|
|
{
|
|
struct sched_group *sg = env->sd->groups;
|
|
struct sg_lb_stats *local = &sds->local_stat;
|
|
struct sg_lb_stats tmp_sgs;
|
|
unsigned long sum_util = 0;
|
|
int sg_status = 0;
|
|
|
|
do {
|
|
struct sg_lb_stats *sgs = &tmp_sgs;
|
|
int local_group;
|
|
|
|
local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg));
|
|
if (local_group) {
|
|
sds->local = sg;
|
|
sgs = local;
|
|
|
|
if (env->idle != CPU_NEWLY_IDLE ||
|
|
time_after_eq(jiffies, sg->sgc->next_update))
|
|
update_group_capacity(env->sd, env->dst_cpu);
|
|
}
|
|
|
|
update_sg_lb_stats(env, sds, sg, sgs, &sg_status);
|
|
|
|
if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
|
|
sds->busiest = sg;
|
|
sds->busiest_stat = *sgs;
|
|
}
|
|
|
|
/* Now, start updating sd_lb_stats */
|
|
sds->total_load += sgs->group_load;
|
|
sds->total_capacity += sgs->group_capacity;
|
|
|
|
sum_util += sgs->group_util;
|
|
sg = sg->next;
|
|
} while (sg != env->sd->groups);
|
|
|
|
/*
|
|
* Indicate that the child domain of the busiest group prefers tasks
|
|
* go to a child's sibling domains first. NB the flags of a sched group
|
|
* are those of the child domain.
|
|
*/
|
|
if (sds->busiest)
|
|
sds->prefer_sibling = !!(sds->busiest->flags & SD_PREFER_SIBLING);
|
|
|
|
|
|
if (env->sd->flags & SD_NUMA)
|
|
env->fbq_type = fbq_classify_group(&sds->busiest_stat);
|
|
|
|
if (!env->sd->parent) {
|
|
struct root_domain *rd = env->dst_rq->rd;
|
|
|
|
/* update overload indicator if we are at root domain */
|
|
WRITE_ONCE(rd->overload, sg_status & SG_OVERLOAD);
|
|
|
|
/* Update over-utilization (tipping point, U >= 0) indicator */
|
|
WRITE_ONCE(rd->overutilized, sg_status & SG_OVERUTILIZED);
|
|
trace_sched_overutilized_tp(rd, sg_status & SG_OVERUTILIZED);
|
|
} else if (sg_status & SG_OVERUTILIZED) {
|
|
struct root_domain *rd = env->dst_rq->rd;
|
|
|
|
WRITE_ONCE(rd->overutilized, SG_OVERUTILIZED);
|
|
trace_sched_overutilized_tp(rd, SG_OVERUTILIZED);
|
|
}
|
|
|
|
update_idle_cpu_scan(env, sum_util);
|
|
}
|
|
|
|
/**
|
|
* calculate_imbalance - Calculate the amount of imbalance present within the
|
|
* groups of a given sched_domain during load balance.
|
|
* @env: load balance environment
|
|
* @sds: statistics of the sched_domain whose imbalance is to be calculated.
|
|
*/
|
|
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
|
|
{
|
|
struct sg_lb_stats *local, *busiest;
|
|
|
|
local = &sds->local_stat;
|
|
busiest = &sds->busiest_stat;
|
|
|
|
if (busiest->group_type == group_misfit_task) {
|
|
if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
|
|
/* Set imbalance to allow misfit tasks to be balanced. */
|
|
env->migration_type = migrate_misfit;
|
|
env->imbalance = 1;
|
|
} else {
|
|
/*
|
|
* Set load imbalance to allow moving task from cpu
|
|
* with reduced capacity.
|
|
*/
|
|
env->migration_type = migrate_load;
|
|
env->imbalance = busiest->group_misfit_task_load;
|
|
}
|
|
return;
|
|
}
|
|
|
|
if (busiest->group_type == group_asym_packing) {
|
|
/*
|
|
* In case of asym capacity, we will try to migrate all load to
|
|
* the preferred CPU.
|
|
*/
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = busiest->sum_h_nr_running;
|
|
return;
|
|
}
|
|
|
|
if (busiest->group_type == group_smt_balance) {
|
|
/* Reduce number of tasks sharing CPU capacity */
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = 1;
|
|
return;
|
|
}
|
|
|
|
if (busiest->group_type == group_imbalanced) {
|
|
/*
|
|
* In the group_imb case we cannot rely on group-wide averages
|
|
* to ensure CPU-load equilibrium, try to move any task to fix
|
|
* the imbalance. The next load balance will take care of
|
|
* balancing back the system.
|
|
*/
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = 1;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Try to use spare capacity of local group without overloading it or
|
|
* emptying busiest.
|
|
*/
|
|
if (local->group_type == group_has_spare) {
|
|
if ((busiest->group_type > group_fully_busy) &&
|
|
!(env->sd->flags & SD_SHARE_LLC)) {
|
|
/*
|
|
* If busiest is overloaded, try to fill spare
|
|
* capacity. This might end up creating spare capacity
|
|
* in busiest or busiest still being overloaded but
|
|
* there is no simple way to directly compute the
|
|
* amount of load to migrate in order to balance the
|
|
* system.
|
|
*/
|
|
env->migration_type = migrate_util;
|
|
env->imbalance = max(local->group_capacity, local->group_util) -
|
|
local->group_util;
|
|
|
|
/*
|
|
* In some cases, the group's utilization is max or even
|
|
* higher than capacity because of migrations but the
|
|
* local CPU is (newly) idle. There is at least one
|
|
* waiting task in this overloaded busiest group. Let's
|
|
* try to pull it.
|
|
*/
|
|
if (env->idle != CPU_NOT_IDLE && env->imbalance == 0) {
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = 1;
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
if (busiest->group_weight == 1 || sds->prefer_sibling) {
|
|
/*
|
|
* When prefer sibling, evenly spread running tasks on
|
|
* groups.
|
|
*/
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = sibling_imbalance(env, sds, busiest, local);
|
|
} else {
|
|
|
|
/*
|
|
* If there is no overload, we just want to even the number of
|
|
* idle cpus.
|
|
*/
|
|
env->migration_type = migrate_task;
|
|
env->imbalance = max_t(long, 0,
|
|
(local->idle_cpus - busiest->idle_cpus));
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/* Consider allowing a small imbalance between NUMA groups */
|
|
if (env->sd->flags & SD_NUMA) {
|
|
env->imbalance = adjust_numa_imbalance(env->imbalance,
|
|
local->sum_nr_running + 1,
|
|
env->sd->imb_numa_nr);
|
|
}
|
|
#endif
|
|
|
|
/* Number of tasks to move to restore balance */
|
|
env->imbalance >>= 1;
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Local is fully busy but has to take more load to relieve the
|
|
* busiest group
|
|
*/
|
|
if (local->group_type < group_overloaded) {
|
|
/*
|
|
* Local will become overloaded so the avg_load metrics are
|
|
* finally needed.
|
|
*/
|
|
|
|
local->avg_load = (local->group_load * SCHED_CAPACITY_SCALE) /
|
|
local->group_capacity;
|
|
|
|
/*
|
|
* If the local group is more loaded than the selected
|
|
* busiest group don't try to pull any tasks.
|
|
*/
|
|
if (local->avg_load >= busiest->avg_load) {
|
|
env->imbalance = 0;
|
|
return;
|
|
}
|
|
|
|
sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
|
|
sds->total_capacity;
|
|
|
|
/*
|
|
* If the local group is more loaded than the average system
|
|
* load, don't try to pull any tasks.
|
|
*/
|
|
if (local->avg_load >= sds->avg_load) {
|
|
env->imbalance = 0;
|
|
return;
|
|
}
|
|
|
|
}
|
|
|
|
/*
|
|
* Both group are or will become overloaded and we're trying to get all
|
|
* the CPUs to the average_load, so we don't want to push ourselves
|
|
* above the average load, nor do we wish to reduce the max loaded CPU
|
|
* below the average load. At the same time, we also don't want to
|
|
* reduce the group load below the group capacity. Thus we look for
|
|
* the minimum possible imbalance.
|
|
*/
|
|
env->migration_type = migrate_load;
|
|
env->imbalance = min(
|
|
(busiest->avg_load - sds->avg_load) * busiest->group_capacity,
|
|
(sds->avg_load - local->avg_load) * local->group_capacity
|
|
) / SCHED_CAPACITY_SCALE;
|
|
}
|
|
|
|
/******* find_busiest_group() helpers end here *********************/
|
|
|
|
/*
|
|
* Decision matrix according to the local and busiest group type:
|
|
*
|
|
* busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
|
|
* has_spare nr_idle balanced N/A N/A balanced balanced
|
|
* fully_busy nr_idle nr_idle N/A N/A balanced balanced
|
|
* misfit_task force N/A N/A N/A N/A N/A
|
|
* asym_packing force force N/A N/A force force
|
|
* imbalanced force force N/A N/A force force
|
|
* overloaded force force N/A N/A force avg_load
|
|
*
|
|
* N/A : Not Applicable because already filtered while updating
|
|
* statistics.
|
|
* balanced : The system is balanced for these 2 groups.
|
|
* force : Calculate the imbalance as load migration is probably needed.
|
|
* avg_load : Only if imbalance is significant enough.
|
|
* nr_idle : dst_cpu is not busy and the number of idle CPUs is quite
|
|
* different in groups.
|
|
*/
|
|
|
|
/**
|
|
* find_busiest_group - Returns the busiest group within the sched_domain
|
|
* if there is an imbalance.
|
|
* @env: The load balancing environment.
|
|
*
|
|
* Also calculates the amount of runnable load which should be moved
|
|
* to restore balance.
|
|
*
|
|
* Return: - The busiest group if imbalance exists.
|
|
*/
|
|
static struct sched_group *find_busiest_group(struct lb_env *env)
|
|
{
|
|
struct sg_lb_stats *local, *busiest;
|
|
struct sd_lb_stats sds;
|
|
|
|
init_sd_lb_stats(&sds);
|
|
|
|
/*
|
|
* Compute the various statistics relevant for load balancing at
|
|
* this level.
|
|
*/
|
|
update_sd_lb_stats(env, &sds);
|
|
|
|
/* There is no busy sibling group to pull tasks from */
|
|
if (!sds.busiest)
|
|
goto out_balanced;
|
|
|
|
busiest = &sds.busiest_stat;
|
|
|
|
/* Misfit tasks should be dealt with regardless of the avg load */
|
|
if (busiest->group_type == group_misfit_task)
|
|
goto force_balance;
|
|
|
|
if (sched_energy_enabled()) {
|
|
struct root_domain *rd = env->dst_rq->rd;
|
|
|
|
if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized))
|
|
goto out_balanced;
|
|
}
|
|
|
|
/* ASYM feature bypasses nice load balance check */
|
|
if (busiest->group_type == group_asym_packing)
|
|
goto force_balance;
|
|
|
|
/*
|
|
* If the busiest group is imbalanced the below checks don't
|
|
* work because they assume all things are equal, which typically
|
|
* isn't true due to cpus_ptr constraints and the like.
|
|
*/
|
|
if (busiest->group_type == group_imbalanced)
|
|
goto force_balance;
|
|
|
|
local = &sds.local_stat;
|
|
/*
|
|
* If the local group is busier than the selected busiest group
|
|
* don't try and pull any tasks.
|
|
*/
|
|
if (local->group_type > busiest->group_type)
|
|
goto out_balanced;
|
|
|
|
/*
|
|
* When groups are overloaded, use the avg_load to ensure fairness
|
|
* between tasks.
|
|
*/
|
|
if (local->group_type == group_overloaded) {
|
|
/*
|
|
* If the local group is more loaded than the selected
|
|
* busiest group don't try to pull any tasks.
|
|
*/
|
|
if (local->avg_load >= busiest->avg_load)
|
|
goto out_balanced;
|
|
|
|
/* XXX broken for overlapping NUMA groups */
|
|
sds.avg_load = (sds.total_load * SCHED_CAPACITY_SCALE) /
|
|
sds.total_capacity;
|
|
|
|
/*
|
|
* Don't pull any tasks if this group is already above the
|
|
* domain average load.
|
|
*/
|
|
if (local->avg_load >= sds.avg_load)
|
|
goto out_balanced;
|
|
|
|
/*
|
|
* If the busiest group is more loaded, use imbalance_pct to be
|
|
* conservative.
|
|
*/
|
|
if (100 * busiest->avg_load <=
|
|
env->sd->imbalance_pct * local->avg_load)
|
|
goto out_balanced;
|
|
}
|
|
|
|
/*
|
|
* Try to move all excess tasks to a sibling domain of the busiest
|
|
* group's child domain.
|
|
*/
|
|
if (sds.prefer_sibling && local->group_type == group_has_spare &&
|
|
sibling_imbalance(env, &sds, busiest, local) > 1)
|
|
goto force_balance;
|
|
|
|
if (busiest->group_type != group_overloaded) {
|
|
if (env->idle == CPU_NOT_IDLE) {
|
|
/*
|
|
* If the busiest group is not overloaded (and as a
|
|
* result the local one too) but this CPU is already
|
|
* busy, let another idle CPU try to pull task.
|
|
*/
|
|
goto out_balanced;
|
|
}
|
|
|
|
if (busiest->group_type == group_smt_balance &&
|
|
smt_vs_nonsmt_groups(sds.local, sds.busiest)) {
|
|
/* Let non SMT CPU pull from SMT CPU sharing with sibling */
|
|
goto force_balance;
|
|
}
|
|
|
|
if (busiest->group_weight > 1 &&
|
|
local->idle_cpus <= (busiest->idle_cpus + 1)) {
|
|
/*
|
|
* If the busiest group is not overloaded
|
|
* and there is no imbalance between this and busiest
|
|
* group wrt idle CPUs, it is balanced. The imbalance
|
|
* becomes significant if the diff is greater than 1
|
|
* otherwise we might end up to just move the imbalance
|
|
* on another group. Of course this applies only if
|
|
* there is more than 1 CPU per group.
|
|
*/
|
|
goto out_balanced;
|
|
}
|
|
|
|
if (busiest->sum_h_nr_running == 1) {
|
|
/*
|
|
* busiest doesn't have any tasks waiting to run
|
|
*/
|
|
goto out_balanced;
|
|
}
|
|
}
|
|
|
|
force_balance:
|
|
/* Looks like there is an imbalance. Compute it */
|
|
calculate_imbalance(env, &sds);
|
|
return env->imbalance ? sds.busiest : NULL;
|
|
|
|
out_balanced:
|
|
env->imbalance = 0;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_queue - find the busiest runqueue among the CPUs in the group.
|
|
*/
|
|
static struct rq *find_busiest_queue(struct lb_env *env,
|
|
struct sched_group *group)
|
|
{
|
|
struct rq *busiest = NULL, *rq;
|
|
unsigned long busiest_util = 0, busiest_load = 0, busiest_capacity = 1;
|
|
unsigned int busiest_nr = 0;
|
|
int i;
|
|
|
|
for_each_cpu_and(i, sched_group_span(group), env->cpus) {
|
|
unsigned long capacity, load, util;
|
|
unsigned int nr_running;
|
|
enum fbq_type rt;
|
|
|
|
rq = cpu_rq(i);
|
|
rt = fbq_classify_rq(rq);
|
|
|
|
/*
|
|
* We classify groups/runqueues into three groups:
|
|
* - regular: there are !numa tasks
|
|
* - remote: there are numa tasks that run on the 'wrong' node
|
|
* - all: there is no distinction
|
|
*
|
|
* In order to avoid migrating ideally placed numa tasks,
|
|
* ignore those when there's better options.
|
|
*
|
|
* If we ignore the actual busiest queue to migrate another
|
|
* task, the next balance pass can still reduce the busiest
|
|
* queue by moving tasks around inside the node.
|
|
*
|
|
* If we cannot move enough load due to this classification
|
|
* the next pass will adjust the group classification and
|
|
* allow migration of more tasks.
|
|
*
|
|
* Both cases only affect the total convergence complexity.
|
|
*/
|
|
if (rt > env->fbq_type)
|
|
continue;
|
|
|
|
nr_running = rq->cfs.h_nr_running;
|
|
if (!nr_running)
|
|
continue;
|
|
|
|
capacity = capacity_of(i);
|
|
|
|
/*
|
|
* For ASYM_CPUCAPACITY domains, don't pick a CPU that could
|
|
* eventually lead to active_balancing high->low capacity.
|
|
* Higher per-CPU capacity is considered better than balancing
|
|
* average load.
|
|
*/
|
|
if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
|
|
!capacity_greater(capacity_of(env->dst_cpu), capacity) &&
|
|
nr_running == 1)
|
|
continue;
|
|
|
|
/*
|
|
* Make sure we only pull tasks from a CPU of lower priority
|
|
* when balancing between SMT siblings.
|
|
*
|
|
* If balancing between cores, let lower priority CPUs help
|
|
* SMT cores with more than one busy sibling.
|
|
*/
|
|
if (sched_asym(env->sd, i, env->dst_cpu) && nr_running == 1)
|
|
continue;
|
|
|
|
switch (env->migration_type) {
|
|
case migrate_load:
|
|
/*
|
|
* When comparing with load imbalance, use cpu_load()
|
|
* which is not scaled with the CPU capacity.
|
|
*/
|
|
load = cpu_load(rq);
|
|
|
|
if (nr_running == 1 && load > env->imbalance &&
|
|
!check_cpu_capacity(rq, env->sd))
|
|
break;
|
|
|
|
/*
|
|
* For the load comparisons with the other CPUs,
|
|
* consider the cpu_load() scaled with the CPU
|
|
* capacity, so that the load can be moved away
|
|
* from the CPU that is potentially running at a
|
|
* lower capacity.
|
|
*
|
|
* Thus we're looking for max(load_i / capacity_i),
|
|
* crosswise multiplication to rid ourselves of the
|
|
* division works out to:
|
|
* load_i * capacity_j > load_j * capacity_i;
|
|
* where j is our previous maximum.
|
|
*/
|
|
if (load * busiest_capacity > busiest_load * capacity) {
|
|
busiest_load = load;
|
|
busiest_capacity = capacity;
|
|
busiest = rq;
|
|
}
|
|
break;
|
|
|
|
case migrate_util:
|
|
util = cpu_util_cfs_boost(i);
|
|
|
|
/*
|
|
* Don't try to pull utilization from a CPU with one
|
|
* running task. Whatever its utilization, we will fail
|
|
* detach the task.
|
|
*/
|
|
if (nr_running <= 1)
|
|
continue;
|
|
|
|
if (busiest_util < util) {
|
|
busiest_util = util;
|
|
busiest = rq;
|
|
}
|
|
break;
|
|
|
|
case migrate_task:
|
|
if (busiest_nr < nr_running) {
|
|
busiest_nr = nr_running;
|
|
busiest = rq;
|
|
}
|
|
break;
|
|
|
|
case migrate_misfit:
|
|
/*
|
|
* For ASYM_CPUCAPACITY domains with misfit tasks we
|
|
* simply seek the "biggest" misfit task.
|
|
*/
|
|
if (rq->misfit_task_load > busiest_load) {
|
|
busiest_load = rq->misfit_task_load;
|
|
busiest = rq;
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
}
|
|
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
|
|
* so long as it is large enough.
|
|
*/
|
|
#define MAX_PINNED_INTERVAL 512
|
|
|
|
static inline bool
|
|
asym_active_balance(struct lb_env *env)
|
|
{
|
|
/*
|
|
* ASYM_PACKING needs to force migrate tasks from busy but lower
|
|
* priority CPUs in order to pack all tasks in the highest priority
|
|
* CPUs. When done between cores, do it only if the whole core if the
|
|
* whole core is idle.
|
|
*
|
|
* If @env::src_cpu is an SMT core with busy siblings, let
|
|
* the lower priority @env::dst_cpu help it. Do not follow
|
|
* CPU priority.
|
|
*/
|
|
return env->idle != CPU_NOT_IDLE && sched_use_asym_prio(env->sd, env->dst_cpu) &&
|
|
(sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
|
|
!sched_use_asym_prio(env->sd, env->src_cpu));
|
|
}
|
|
|
|
static inline bool
|
|
imbalanced_active_balance(struct lb_env *env)
|
|
{
|
|
struct sched_domain *sd = env->sd;
|
|
|
|
/*
|
|
* The imbalanced case includes the case of pinned tasks preventing a fair
|
|
* distribution of the load on the system but also the even distribution of the
|
|
* threads on a system with spare capacity
|
|
*/
|
|
if ((env->migration_type == migrate_task) &&
|
|
(sd->nr_balance_failed > sd->cache_nice_tries+2))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int need_active_balance(struct lb_env *env)
|
|
{
|
|
struct sched_domain *sd = env->sd;
|
|
|
|
if (asym_active_balance(env))
|
|
return 1;
|
|
|
|
if (imbalanced_active_balance(env))
|
|
return 1;
|
|
|
|
/*
|
|
* The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
|
|
* It's worth migrating the task if the src_cpu's capacity is reduced
|
|
* because of other sched_class or IRQs if more capacity stays
|
|
* available on dst_cpu.
|
|
*/
|
|
if ((env->idle != CPU_NOT_IDLE) &&
|
|
(env->src_rq->cfs.h_nr_running == 1)) {
|
|
if ((check_cpu_capacity(env->src_rq, sd)) &&
|
|
(capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
|
|
return 1;
|
|
}
|
|
|
|
if (env->migration_type == migrate_misfit)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int active_load_balance_cpu_stop(void *data);
|
|
|
|
static int should_we_balance(struct lb_env *env)
|
|
{
|
|
struct cpumask *swb_cpus = this_cpu_cpumask_var_ptr(should_we_balance_tmpmask);
|
|
struct sched_group *sg = env->sd->groups;
|
|
int cpu, idle_smt = -1;
|
|
|
|
/*
|
|
* Ensure the balancing environment is consistent; can happen
|
|
* when the softirq triggers 'during' hotplug.
|
|
*/
|
|
if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
|
|
return 0;
|
|
|
|
/*
|
|
* In the newly idle case, we will allow all the CPUs
|
|
* to do the newly idle load balance.
|
|
*
|
|
* However, we bail out if we already have tasks or a wakeup pending,
|
|
* to optimize wakeup latency.
|
|
*/
|
|
if (env->idle == CPU_NEWLY_IDLE) {
|
|
if (env->dst_rq->nr_running > 0 || env->dst_rq->ttwu_pending)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
cpumask_copy(swb_cpus, group_balance_mask(sg));
|
|
/* Try to find first idle CPU */
|
|
for_each_cpu_and(cpu, swb_cpus, env->cpus) {
|
|
if (!idle_cpu(cpu))
|
|
continue;
|
|
|
|
/*
|
|
* Don't balance to idle SMT in busy core right away when
|
|
* balancing cores, but remember the first idle SMT CPU for
|
|
* later consideration. Find CPU on an idle core first.
|
|
*/
|
|
if (!(env->sd->flags & SD_SHARE_CPUCAPACITY) && !is_core_idle(cpu)) {
|
|
if (idle_smt == -1)
|
|
idle_smt = cpu;
|
|
/*
|
|
* If the core is not idle, and first SMT sibling which is
|
|
* idle has been found, then its not needed to check other
|
|
* SMT siblings for idleness:
|
|
*/
|
|
#ifdef CONFIG_SCHED_SMT
|
|
cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
|
|
#endif
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Are we the first idle core in a non-SMT domain or higher,
|
|
* or the first idle CPU in a SMT domain?
|
|
*/
|
|
return cpu == env->dst_cpu;
|
|
}
|
|
|
|
/* Are we the first idle CPU with busy siblings? */
|
|
if (idle_smt != -1)
|
|
return idle_smt == env->dst_cpu;
|
|
|
|
/* Are we the first CPU of this group ? */
|
|
return group_balance_cpu(sg) == env->dst_cpu;
|
|
}
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*/
|
|
static int load_balance(int this_cpu, struct rq *this_rq,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *continue_balancing)
|
|
{
|
|
int ld_moved, cur_ld_moved, active_balance = 0;
|
|
struct sched_domain *sd_parent = sd->parent;
|
|
struct sched_group *group;
|
|
struct rq *busiest;
|
|
struct rq_flags rf;
|
|
struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
|
|
struct lb_env env = {
|
|
.sd = sd,
|
|
.dst_cpu = this_cpu,
|
|
.dst_rq = this_rq,
|
|
.dst_grpmask = group_balance_mask(sd->groups),
|
|
.idle = idle,
|
|
.loop_break = SCHED_NR_MIGRATE_BREAK,
|
|
.cpus = cpus,
|
|
.fbq_type = all,
|
|
.tasks = LIST_HEAD_INIT(env.tasks),
|
|
};
|
|
|
|
cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
|
|
|
|
schedstat_inc(sd->lb_count[idle]);
|
|
|
|
redo:
|
|
if (!should_we_balance(&env)) {
|
|
*continue_balancing = 0;
|
|
goto out_balanced;
|
|
}
|
|
|
|
group = find_busiest_group(&env);
|
|
if (!group) {
|
|
schedstat_inc(sd->lb_nobusyg[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
busiest = find_busiest_queue(&env, group);
|
|
if (!busiest) {
|
|
schedstat_inc(sd->lb_nobusyq[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
WARN_ON_ONCE(busiest == env.dst_rq);
|
|
|
|
schedstat_add(sd->lb_imbalance[idle], env.imbalance);
|
|
|
|
env.src_cpu = busiest->cpu;
|
|
env.src_rq = busiest;
|
|
|
|
ld_moved = 0;
|
|
/* Clear this flag as soon as we find a pullable task */
|
|
env.flags |= LBF_ALL_PINNED;
|
|
if (busiest->nr_running > 1) {
|
|
/*
|
|
* Attempt to move tasks. If find_busiest_group has found
|
|
* an imbalance but busiest->nr_running <= 1, the group is
|
|
* still unbalanced. ld_moved simply stays zero, so it is
|
|
* correctly treated as an imbalance.
|
|
*/
|
|
env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
|
|
|
|
more_balance:
|
|
rq_lock_irqsave(busiest, &rf);
|
|
update_rq_clock(busiest);
|
|
|
|
/*
|
|
* cur_ld_moved - load moved in current iteration
|
|
* ld_moved - cumulative load moved across iterations
|
|
*/
|
|
cur_ld_moved = detach_tasks(&env);
|
|
|
|
/*
|
|
* We've detached some tasks from busiest_rq. Every
|
|
* task is masked "TASK_ON_RQ_MIGRATING", so we can safely
|
|
* unlock busiest->lock, and we are able to be sure
|
|
* that nobody can manipulate the tasks in parallel.
|
|
* See task_rq_lock() family for the details.
|
|
*/
|
|
|
|
rq_unlock(busiest, &rf);
|
|
|
|
if (cur_ld_moved) {
|
|
attach_tasks(&env);
|
|
ld_moved += cur_ld_moved;
|
|
}
|
|
|
|
local_irq_restore(rf.flags);
|
|
|
|
if (env.flags & LBF_NEED_BREAK) {
|
|
env.flags &= ~LBF_NEED_BREAK;
|
|
/* Stop if we tried all running tasks */
|
|
if (env.loop < busiest->nr_running)
|
|
goto more_balance;
|
|
}
|
|
|
|
/*
|
|
* Revisit (affine) tasks on src_cpu that couldn't be moved to
|
|
* us and move them to an alternate dst_cpu in our sched_group
|
|
* where they can run. The upper limit on how many times we
|
|
* iterate on same src_cpu is dependent on number of CPUs in our
|
|
* sched_group.
|
|
*
|
|
* This changes load balance semantics a bit on who can move
|
|
* load to a given_cpu. In addition to the given_cpu itself
|
|
* (or a ilb_cpu acting on its behalf where given_cpu is
|
|
* nohz-idle), we now have balance_cpu in a position to move
|
|
* load to given_cpu. In rare situations, this may cause
|
|
* conflicts (balance_cpu and given_cpu/ilb_cpu deciding
|
|
* _independently_ and at _same_ time to move some load to
|
|
* given_cpu) causing excess load to be moved to given_cpu.
|
|
* This however should not happen so much in practice and
|
|
* moreover subsequent load balance cycles should correct the
|
|
* excess load moved.
|
|
*/
|
|
if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
|
|
|
|
/* Prevent to re-select dst_cpu via env's CPUs */
|
|
__cpumask_clear_cpu(env.dst_cpu, env.cpus);
|
|
|
|
env.dst_rq = cpu_rq(env.new_dst_cpu);
|
|
env.dst_cpu = env.new_dst_cpu;
|
|
env.flags &= ~LBF_DST_PINNED;
|
|
env.loop = 0;
|
|
env.loop_break = SCHED_NR_MIGRATE_BREAK;
|
|
|
|
/*
|
|
* Go back to "more_balance" rather than "redo" since we
|
|
* need to continue with same src_cpu.
|
|
*/
|
|
goto more_balance;
|
|
}
|
|
|
|
/*
|
|
* We failed to reach balance because of affinity.
|
|
*/
|
|
if (sd_parent) {
|
|
int *group_imbalance = &sd_parent->groups->sgc->imbalance;
|
|
|
|
if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
|
|
*group_imbalance = 1;
|
|
}
|
|
|
|
/* All tasks on this runqueue were pinned by CPU affinity */
|
|
if (unlikely(env.flags & LBF_ALL_PINNED)) {
|
|
__cpumask_clear_cpu(cpu_of(busiest), cpus);
|
|
/*
|
|
* Attempting to continue load balancing at the current
|
|
* sched_domain level only makes sense if there are
|
|
* active CPUs remaining as possible busiest CPUs to
|
|
* pull load from which are not contained within the
|
|
* destination group that is receiving any migrated
|
|
* load.
|
|
*/
|
|
if (!cpumask_subset(cpus, env.dst_grpmask)) {
|
|
env.loop = 0;
|
|
env.loop_break = SCHED_NR_MIGRATE_BREAK;
|
|
goto redo;
|
|
}
|
|
goto out_all_pinned;
|
|
}
|
|
}
|
|
|
|
if (!ld_moved) {
|
|
schedstat_inc(sd->lb_failed[idle]);
|
|
/*
|
|
* Increment the failure counter only on periodic balance.
|
|
* We do not want newidle balance, which can be very
|
|
* frequent, pollute the failure counter causing
|
|
* excessive cache_hot migrations and active balances.
|
|
*/
|
|
if (idle != CPU_NEWLY_IDLE)
|
|
sd->nr_balance_failed++;
|
|
|
|
if (need_active_balance(&env)) {
|
|
unsigned long flags;
|
|
|
|
raw_spin_rq_lock_irqsave(busiest, flags);
|
|
|
|
/*
|
|
* Don't kick the active_load_balance_cpu_stop,
|
|
* if the curr task on busiest CPU can't be
|
|
* moved to this_cpu:
|
|
*/
|
|
if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
|
|
raw_spin_rq_unlock_irqrestore(busiest, flags);
|
|
goto out_one_pinned;
|
|
}
|
|
|
|
/* Record that we found at least one task that could run on this_cpu */
|
|
env.flags &= ~LBF_ALL_PINNED;
|
|
|
|
/*
|
|
* ->active_balance synchronizes accesses to
|
|
* ->active_balance_work. Once set, it's cleared
|
|
* only after active load balance is finished.
|
|
*/
|
|
if (!busiest->active_balance) {
|
|
busiest->active_balance = 1;
|
|
busiest->push_cpu = this_cpu;
|
|
active_balance = 1;
|
|
}
|
|
|
|
preempt_disable();
|
|
raw_spin_rq_unlock_irqrestore(busiest, flags);
|
|
if (active_balance) {
|
|
stop_one_cpu_nowait(cpu_of(busiest),
|
|
active_load_balance_cpu_stop, busiest,
|
|
&busiest->active_balance_work);
|
|
}
|
|
preempt_enable();
|
|
}
|
|
} else {
|
|
sd->nr_balance_failed = 0;
|
|
}
|
|
|
|
if (likely(!active_balance) || need_active_balance(&env)) {
|
|
/* We were unbalanced, so reset the balancing interval */
|
|
sd->balance_interval = sd->min_interval;
|
|
}
|
|
|
|
goto out;
|
|
|
|
out_balanced:
|
|
/*
|
|
* We reach balance although we may have faced some affinity
|
|
* constraints. Clear the imbalance flag only if other tasks got
|
|
* a chance to move and fix the imbalance.
|
|
*/
|
|
if (sd_parent && !(env.flags & LBF_ALL_PINNED)) {
|
|
int *group_imbalance = &sd_parent->groups->sgc->imbalance;
|
|
|
|
if (*group_imbalance)
|
|
*group_imbalance = 0;
|
|
}
|
|
|
|
out_all_pinned:
|
|
/*
|
|
* We reach balance because all tasks are pinned at this level so
|
|
* we can't migrate them. Let the imbalance flag set so parent level
|
|
* can try to migrate them.
|
|
*/
|
|
schedstat_inc(sd->lb_balanced[idle]);
|
|
|
|
sd->nr_balance_failed = 0;
|
|
|
|
out_one_pinned:
|
|
ld_moved = 0;
|
|
|
|
/*
|
|
* newidle_balance() disregards balance intervals, so we could
|
|
* repeatedly reach this code, which would lead to balance_interval
|
|
* skyrocketing in a short amount of time. Skip the balance_interval
|
|
* increase logic to avoid that.
|
|
*/
|
|
if (env.idle == CPU_NEWLY_IDLE)
|
|
goto out;
|
|
|
|
/* tune up the balancing interval */
|
|
if ((env.flags & LBF_ALL_PINNED &&
|
|
sd->balance_interval < MAX_PINNED_INTERVAL) ||
|
|
sd->balance_interval < sd->max_interval)
|
|
sd->balance_interval *= 2;
|
|
out:
|
|
return ld_moved;
|
|
}
|
|
|
|
static inline unsigned long
|
|
get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
|
|
{
|
|
unsigned long interval = sd->balance_interval;
|
|
|
|
if (cpu_busy)
|
|
interval *= sd->busy_factor;
|
|
|
|
/* scale ms to jiffies */
|
|
interval = msecs_to_jiffies(interval);
|
|
|
|
/*
|
|
* Reduce likelihood of busy balancing at higher domains racing with
|
|
* balancing at lower domains by preventing their balancing periods
|
|
* from being multiples of each other.
|
|
*/
|
|
if (cpu_busy)
|
|
interval -= 1;
|
|
|
|
interval = clamp(interval, 1UL, max_load_balance_interval);
|
|
|
|
return interval;
|
|
}
|
|
|
|
static inline void
|
|
update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
|
|
{
|
|
unsigned long interval, next;
|
|
|
|
/* used by idle balance, so cpu_busy = 0 */
|
|
interval = get_sd_balance_interval(sd, 0);
|
|
next = sd->last_balance + interval;
|
|
|
|
if (time_after(*next_balance, next))
|
|
*next_balance = next;
|
|
}
|
|
|
|
/*
|
|
* active_load_balance_cpu_stop is run by the CPU stopper. It pushes
|
|
* running tasks off the busiest CPU onto idle CPUs. It requires at
|
|
* least 1 task to be running on each physical CPU where possible, and
|
|
* avoids physical / logical imbalances.
|
|
*/
|
|
static int active_load_balance_cpu_stop(void *data)
|
|
{
|
|
struct rq *busiest_rq = data;
|
|
int busiest_cpu = cpu_of(busiest_rq);
|
|
int target_cpu = busiest_rq->push_cpu;
|
|
struct rq *target_rq = cpu_rq(target_cpu);
|
|
struct sched_domain *sd;
|
|
struct task_struct *p = NULL;
|
|
struct rq_flags rf;
|
|
|
|
rq_lock_irq(busiest_rq, &rf);
|
|
/*
|
|
* Between queueing the stop-work and running it is a hole in which
|
|
* CPUs can become inactive. We should not move tasks from or to
|
|
* inactive CPUs.
|
|
*/
|
|
if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
|
|
goto out_unlock;
|
|
|
|
/* Make sure the requested CPU hasn't gone down in the meantime: */
|
|
if (unlikely(busiest_cpu != smp_processor_id() ||
|
|
!busiest_rq->active_balance))
|
|
goto out_unlock;
|
|
|
|
/* Is there any task to move? */
|
|
if (busiest_rq->nr_running <= 1)
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* This condition is "impossible", if it occurs
|
|
* we need to fix it. Originally reported by
|
|
* Bjorn Helgaas on a 128-CPU setup.
|
|
*/
|
|
WARN_ON_ONCE(busiest_rq == target_rq);
|
|
|
|
/* Search for an sd spanning us and the target CPU. */
|
|
rcu_read_lock();
|
|
for_each_domain(target_cpu, sd) {
|
|
if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
|
|
break;
|
|
}
|
|
|
|
if (likely(sd)) {
|
|
struct lb_env env = {
|
|
.sd = sd,
|
|
.dst_cpu = target_cpu,
|
|
.dst_rq = target_rq,
|
|
.src_cpu = busiest_rq->cpu,
|
|
.src_rq = busiest_rq,
|
|
.idle = CPU_IDLE,
|
|
.flags = LBF_ACTIVE_LB,
|
|
};
|
|
|
|
schedstat_inc(sd->alb_count);
|
|
update_rq_clock(busiest_rq);
|
|
|
|
p = detach_one_task(&env);
|
|
if (p) {
|
|
schedstat_inc(sd->alb_pushed);
|
|
/* Active balancing done, reset the failure counter. */
|
|
sd->nr_balance_failed = 0;
|
|
} else {
|
|
schedstat_inc(sd->alb_failed);
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
out_unlock:
|
|
busiest_rq->active_balance = 0;
|
|
rq_unlock(busiest_rq, &rf);
|
|
|
|
if (p)
|
|
attach_one_task(target_rq, p);
|
|
|
|
local_irq_enable();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(balancing);
|
|
|
|
/*
|
|
* Scale the max load_balance interval with the number of CPUs in the system.
|
|
* This trades load-balance latency on larger machines for less cross talk.
|
|
*/
|
|
void update_max_interval(void)
|
|
{
|
|
max_load_balance_interval = HZ*num_online_cpus()/10;
|
|
}
|
|
|
|
static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost)
|
|
{
|
|
if (cost > sd->max_newidle_lb_cost) {
|
|
/*
|
|
* Track max cost of a domain to make sure to not delay the
|
|
* next wakeup on the CPU.
|
|
*/
|
|
sd->max_newidle_lb_cost = cost;
|
|
sd->last_decay_max_lb_cost = jiffies;
|
|
} else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) {
|
|
/*
|
|
* Decay the newidle max times by ~1% per second to ensure that
|
|
* it is not outdated and the current max cost is actually
|
|
* shorter.
|
|
*/
|
|
sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
|
|
sd->last_decay_max_lb_cost = jiffies;
|
|
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* It checks each scheduling domain to see if it is due to be balanced,
|
|
* and initiates a balancing operation if so.
|
|
*
|
|
* Balancing parameters are set up in init_sched_domains.
|
|
*/
|
|
static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle)
|
|
{
|
|
int continue_balancing = 1;
|
|
int cpu = rq->cpu;
|
|
int busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
|
|
unsigned long interval;
|
|
struct sched_domain *sd;
|
|
/* Earliest time when we have to do rebalance again */
|
|
unsigned long next_balance = jiffies + 60*HZ;
|
|
int update_next_balance = 0;
|
|
int need_serialize, need_decay = 0;
|
|
u64 max_cost = 0;
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
/*
|
|
* Decay the newidle max times here because this is a regular
|
|
* visit to all the domains.
|
|
*/
|
|
need_decay = update_newidle_cost(sd, 0);
|
|
max_cost += sd->max_newidle_lb_cost;
|
|
|
|
/*
|
|
* Stop the load balance at this level. There is another
|
|
* CPU in our sched group which is doing load balancing more
|
|
* actively.
|
|
*/
|
|
if (!continue_balancing) {
|
|
if (need_decay)
|
|
continue;
|
|
break;
|
|
}
|
|
|
|
interval = get_sd_balance_interval(sd, busy);
|
|
|
|
need_serialize = sd->flags & SD_SERIALIZE;
|
|
if (need_serialize) {
|
|
if (!spin_trylock(&balancing))
|
|
goto out;
|
|
}
|
|
|
|
if (time_after_eq(jiffies, sd->last_balance + interval)) {
|
|
if (load_balance(cpu, rq, sd, idle, &continue_balancing)) {
|
|
/*
|
|
* The LBF_DST_PINNED logic could have changed
|
|
* env->dst_cpu, so we can't know our idle
|
|
* state even if we migrated tasks. Update it.
|
|
*/
|
|
idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
|
|
busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
|
|
}
|
|
sd->last_balance = jiffies;
|
|
interval = get_sd_balance_interval(sd, busy);
|
|
}
|
|
if (need_serialize)
|
|
spin_unlock(&balancing);
|
|
out:
|
|
if (time_after(next_balance, sd->last_balance + interval)) {
|
|
next_balance = sd->last_balance + interval;
|
|
update_next_balance = 1;
|
|
}
|
|
}
|
|
if (need_decay) {
|
|
/*
|
|
* Ensure the rq-wide value also decays but keep it at a
|
|
* reasonable floor to avoid funnies with rq->avg_idle.
|
|
*/
|
|
rq->max_idle_balance_cost =
|
|
max((u64)sysctl_sched_migration_cost, max_cost);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* next_balance will be updated only when there is a need.
|
|
* When the cpu is attached to null domain for ex, it will not be
|
|
* updated.
|
|
*/
|
|
if (likely(update_next_balance))
|
|
rq->next_balance = next_balance;
|
|
|
|
}
|
|
|
|
static inline int on_null_domain(struct rq *rq)
|
|
{
|
|
return unlikely(!rcu_dereference_sched(rq->sd));
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
/*
|
|
* NOHZ idle load balancing (ILB) details:
|
|
*
|
|
* - When one of the busy CPUs notices that there may be an idle rebalancing
|
|
* needed, they will kick the idle load balancer, which then does idle
|
|
* load balancing for all the idle CPUs.
|
|
*
|
|
* - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
|
|
* anywhere yet.
|
|
*/
|
|
static inline int find_new_ilb(void)
|
|
{
|
|
const struct cpumask *hk_mask;
|
|
int ilb_cpu;
|
|
|
|
hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
|
|
|
|
for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
|
|
|
|
if (ilb_cpu == smp_processor_id())
|
|
continue;
|
|
|
|
if (idle_cpu(ilb_cpu))
|
|
return ilb_cpu;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
|
|
* SMP function call (IPI).
|
|
*
|
|
* We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
|
|
*/
|
|
static void kick_ilb(unsigned int flags)
|
|
{
|
|
int ilb_cpu;
|
|
|
|
/*
|
|
* Increase nohz.next_balance only when if full ilb is triggered but
|
|
* not if we only update stats.
|
|
*/
|
|
if (flags & NOHZ_BALANCE_KICK)
|
|
nohz.next_balance = jiffies+1;
|
|
|
|
ilb_cpu = find_new_ilb();
|
|
if (ilb_cpu < 0)
|
|
return;
|
|
|
|
/*
|
|
* Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
|
|
* the first flag owns it; cleared by nohz_csd_func().
|
|
*/
|
|
flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
|
|
if (flags & NOHZ_KICK_MASK)
|
|
return;
|
|
|
|
/*
|
|
* This way we generate an IPI on the target CPU which
|
|
* is idle, and the softirq performing NOHZ idle load balancing
|
|
* will be run before returning from the IPI.
|
|
*/
|
|
smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
|
|
}
|
|
|
|
/*
|
|
* Current decision point for kicking the idle load balancer in the presence
|
|
* of idle CPUs in the system.
|
|
*/
|
|
static void nohz_balancer_kick(struct rq *rq)
|
|
{
|
|
unsigned long now = jiffies;
|
|
struct sched_domain_shared *sds;
|
|
struct sched_domain *sd;
|
|
int nr_busy, i, cpu = rq->cpu;
|
|
unsigned int flags = 0;
|
|
|
|
if (unlikely(rq->idle_balance))
|
|
return;
|
|
|
|
/*
|
|
* We may be recently in ticked or tickless idle mode. At the first
|
|
* busy tick after returning from idle, we will update the busy stats.
|
|
*/
|
|
nohz_balance_exit_idle(rq);
|
|
|
|
/*
|
|
* None are in tickless mode and hence no need for NOHZ idle load
|
|
* balancing:
|
|
*/
|
|
if (likely(!atomic_read(&nohz.nr_cpus)))
|
|
return;
|
|
|
|
if (READ_ONCE(nohz.has_blocked) &&
|
|
time_after(now, READ_ONCE(nohz.next_blocked)))
|
|
flags = NOHZ_STATS_KICK;
|
|
|
|
if (time_before(now, nohz.next_balance))
|
|
goto out;
|
|
|
|
if (rq->nr_running >= 2) {
|
|
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
|
|
goto out;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
|
|
sd = rcu_dereference(rq->sd);
|
|
if (sd) {
|
|
/*
|
|
* If there's a runnable CFS task and the current CPU has reduced
|
|
* capacity, kick the ILB to see if there's a better CPU to run on:
|
|
*/
|
|
if (rq->cfs.h_nr_running >= 1 && check_cpu_capacity(rq, sd)) {
|
|
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
|
|
goto unlock;
|
|
}
|
|
}
|
|
|
|
sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
|
|
if (sd) {
|
|
/*
|
|
* When ASYM_PACKING; see if there's a more preferred CPU
|
|
* currently idle; in which case, kick the ILB to move tasks
|
|
* around.
|
|
*
|
|
* When balancing betwen cores, all the SMT siblings of the
|
|
* preferred CPU must be idle.
|
|
*/
|
|
for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
|
|
if (sched_asym(sd, i, cpu)) {
|
|
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
|
|
goto unlock;
|
|
}
|
|
}
|
|
}
|
|
|
|
sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, cpu));
|
|
if (sd) {
|
|
/*
|
|
* When ASYM_CPUCAPACITY; see if there's a higher capacity CPU
|
|
* to run the misfit task on.
|
|
*/
|
|
if (check_misfit_status(rq, sd)) {
|
|
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
|
|
goto unlock;
|
|
}
|
|
|
|
/*
|
|
* For asymmetric systems, we do not want to nicely balance
|
|
* cache use, instead we want to embrace asymmetry and only
|
|
* ensure tasks have enough CPU capacity.
|
|
*
|
|
* Skip the LLC logic because it's not relevant in that case.
|
|
*/
|
|
goto unlock;
|
|
}
|
|
|
|
sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
|
|
if (sds) {
|
|
/*
|
|
* If there is an imbalance between LLC domains (IOW we could
|
|
* increase the overall cache utilization), we need a less-loaded LLC
|
|
* domain to pull some load from. Likewise, we may need to spread
|
|
* load within the current LLC domain (e.g. packed SMT cores but
|
|
* other CPUs are idle). We can't really know from here how busy
|
|
* the others are - so just get a NOHZ balance going if it looks
|
|
* like this LLC domain has tasks we could move.
|
|
*/
|
|
nr_busy = atomic_read(&sds->nr_busy_cpus);
|
|
if (nr_busy > 1) {
|
|
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
|
|
goto unlock;
|
|
}
|
|
}
|
|
unlock:
|
|
rcu_read_unlock();
|
|
out:
|
|
if (READ_ONCE(nohz.needs_update))
|
|
flags |= NOHZ_NEXT_KICK;
|
|
|
|
if (flags)
|
|
kick_ilb(flags);
|
|
}
|
|
|
|
static void set_cpu_sd_state_busy(int cpu)
|
|
{
|
|
struct sched_domain *sd;
|
|
|
|
rcu_read_lock();
|
|
sd = rcu_dereference(per_cpu(sd_llc, cpu));
|
|
|
|
if (!sd || !sd->nohz_idle)
|
|
goto unlock;
|
|
sd->nohz_idle = 0;
|
|
|
|
atomic_inc(&sd->shared->nr_busy_cpus);
|
|
unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
void nohz_balance_exit_idle(struct rq *rq)
|
|
{
|
|
SCHED_WARN_ON(rq != this_rq());
|
|
|
|
if (likely(!rq->nohz_tick_stopped))
|
|
return;
|
|
|
|
rq->nohz_tick_stopped = 0;
|
|
cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
|
|
atomic_dec(&nohz.nr_cpus);
|
|
|
|
set_cpu_sd_state_busy(rq->cpu);
|
|
}
|
|
|
|
static void set_cpu_sd_state_idle(int cpu)
|
|
{
|
|
struct sched_domain *sd;
|
|
|
|
rcu_read_lock();
|
|
sd = rcu_dereference(per_cpu(sd_llc, cpu));
|
|
|
|
if (!sd || sd->nohz_idle)
|
|
goto unlock;
|
|
sd->nohz_idle = 1;
|
|
|
|
atomic_dec(&sd->shared->nr_busy_cpus);
|
|
unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* This routine will record that the CPU is going idle with tick stopped.
|
|
* This info will be used in performing idle load balancing in the future.
|
|
*/
|
|
void nohz_balance_enter_idle(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
SCHED_WARN_ON(cpu != smp_processor_id());
|
|
|
|
/* If this CPU is going down, then nothing needs to be done: */
|
|
if (!cpu_active(cpu))
|
|
return;
|
|
|
|
/* Spare idle load balancing on CPUs that don't want to be disturbed: */
|
|
if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
|
|
return;
|
|
|
|
/*
|
|
* Can be set safely without rq->lock held
|
|
* If a clear happens, it will have evaluated last additions because
|
|
* rq->lock is held during the check and the clear
|
|
*/
|
|
rq->has_blocked_load = 1;
|
|
|
|
/*
|
|
* The tick is still stopped but load could have been added in the
|
|
* meantime. We set the nohz.has_blocked flag to trig a check of the
|
|
* *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
|
|
* of nohz.has_blocked can only happen after checking the new load
|
|
*/
|
|
if (rq->nohz_tick_stopped)
|
|
goto out;
|
|
|
|
/* If we're a completely isolated CPU, we don't play: */
|
|
if (on_null_domain(rq))
|
|
return;
|
|
|
|
rq->nohz_tick_stopped = 1;
|
|
|
|
cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
|
|
atomic_inc(&nohz.nr_cpus);
|
|
|
|
/*
|
|
* Ensures that if nohz_idle_balance() fails to observe our
|
|
* @idle_cpus_mask store, it must observe the @has_blocked
|
|
* and @needs_update stores.
|
|
*/
|
|
smp_mb__after_atomic();
|
|
|
|
set_cpu_sd_state_idle(cpu);
|
|
|
|
WRITE_ONCE(nohz.needs_update, 1);
|
|
out:
|
|
/*
|
|
* Each time a cpu enter idle, we assume that it has blocked load and
|
|
* enable the periodic update of the load of idle cpus
|
|
*/
|
|
WRITE_ONCE(nohz.has_blocked, 1);
|
|
}
|
|
|
|
static bool update_nohz_stats(struct rq *rq)
|
|
{
|
|
unsigned int cpu = rq->cpu;
|
|
|
|
if (!rq->has_blocked_load)
|
|
return false;
|
|
|
|
if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
|
|
return false;
|
|
|
|
if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
|
|
return true;
|
|
|
|
update_blocked_averages(cpu);
|
|
|
|
return rq->has_blocked_load;
|
|
}
|
|
|
|
/*
|
|
* Internal function that runs load balance for all idle cpus. The load balance
|
|
* can be a simple update of blocked load or a complete load balance with
|
|
* tasks movement depending of flags.
|
|
*/
|
|
static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
|
|
{
|
|
/* Earliest time when we have to do rebalance again */
|
|
unsigned long now = jiffies;
|
|
unsigned long next_balance = now + 60*HZ;
|
|
bool has_blocked_load = false;
|
|
int update_next_balance = 0;
|
|
int this_cpu = this_rq->cpu;
|
|
int balance_cpu;
|
|
struct rq *rq;
|
|
|
|
SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
|
|
|
|
/*
|
|
* We assume there will be no idle load after this update and clear
|
|
* the has_blocked flag. If a cpu enters idle in the mean time, it will
|
|
* set the has_blocked flag and trigger another update of idle load.
|
|
* Because a cpu that becomes idle, is added to idle_cpus_mask before
|
|
* setting the flag, we are sure to not clear the state and not
|
|
* check the load of an idle cpu.
|
|
*
|
|
* Same applies to idle_cpus_mask vs needs_update.
|
|
*/
|
|
if (flags & NOHZ_STATS_KICK)
|
|
WRITE_ONCE(nohz.has_blocked, 0);
|
|
if (flags & NOHZ_NEXT_KICK)
|
|
WRITE_ONCE(nohz.needs_update, 0);
|
|
|
|
/*
|
|
* Ensures that if we miss the CPU, we must see the has_blocked
|
|
* store from nohz_balance_enter_idle().
|
|
*/
|
|
smp_mb();
|
|
|
|
/*
|
|
* Start with the next CPU after this_cpu so we will end with this_cpu and let a
|
|
* chance for other idle cpu to pull load.
|
|
*/
|
|
for_each_cpu_wrap(balance_cpu, nohz.idle_cpus_mask, this_cpu+1) {
|
|
if (!idle_cpu(balance_cpu))
|
|
continue;
|
|
|
|
/*
|
|
* If this CPU gets work to do, stop the load balancing
|
|
* work being done for other CPUs. Next load
|
|
* balancing owner will pick it up.
|
|
*/
|
|
if (need_resched()) {
|
|
if (flags & NOHZ_STATS_KICK)
|
|
has_blocked_load = true;
|
|
if (flags & NOHZ_NEXT_KICK)
|
|
WRITE_ONCE(nohz.needs_update, 1);
|
|
goto abort;
|
|
}
|
|
|
|
rq = cpu_rq(balance_cpu);
|
|
|
|
if (flags & NOHZ_STATS_KICK)
|
|
has_blocked_load |= update_nohz_stats(rq);
|
|
|
|
/*
|
|
* If time for next balance is due,
|
|
* do the balance.
|
|
*/
|
|
if (time_after_eq(jiffies, rq->next_balance)) {
|
|
struct rq_flags rf;
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
update_rq_clock(rq);
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
|
|
if (flags & NOHZ_BALANCE_KICK)
|
|
rebalance_domains(rq, CPU_IDLE);
|
|
}
|
|
|
|
if (time_after(next_balance, rq->next_balance)) {
|
|
next_balance = rq->next_balance;
|
|
update_next_balance = 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* next_balance will be updated only when there is a need.
|
|
* When the CPU is attached to null domain for ex, it will not be
|
|
* updated.
|
|
*/
|
|
if (likely(update_next_balance))
|
|
nohz.next_balance = next_balance;
|
|
|
|
if (flags & NOHZ_STATS_KICK)
|
|
WRITE_ONCE(nohz.next_blocked,
|
|
now + msecs_to_jiffies(LOAD_AVG_PERIOD));
|
|
|
|
abort:
|
|
/* There is still blocked load, enable periodic update */
|
|
if (has_blocked_load)
|
|
WRITE_ONCE(nohz.has_blocked, 1);
|
|
}
|
|
|
|
/*
|
|
* In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
|
|
* rebalancing for all the cpus for whom scheduler ticks are stopped.
|
|
*/
|
|
static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
|
|
{
|
|
unsigned int flags = this_rq->nohz_idle_balance;
|
|
|
|
if (!flags)
|
|
return false;
|
|
|
|
this_rq->nohz_idle_balance = 0;
|
|
|
|
if (idle != CPU_IDLE)
|
|
return false;
|
|
|
|
_nohz_idle_balance(this_rq, flags);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Check if we need to directly run the ILB for updating blocked load before
|
|
* entering idle state. Here we run ILB directly without issuing IPIs.
|
|
*
|
|
* Note that when this function is called, the tick may not yet be stopped on
|
|
* this CPU yet. nohz.idle_cpus_mask is updated only when tick is stopped and
|
|
* cleared on the next busy tick. In other words, nohz.idle_cpus_mask updates
|
|
* don't align with CPUs enter/exit idle to avoid bottlenecks due to high idle
|
|
* entry/exit rate (usec). So it is possible that _nohz_idle_balance() is
|
|
* called from this function on (this) CPU that's not yet in the mask. That's
|
|
* OK because the goal of nohz_run_idle_balance() is to run ILB only for
|
|
* updating the blocked load of already idle CPUs without waking up one of
|
|
* those idle CPUs and outside the preempt disable / irq off phase of the local
|
|
* cpu about to enter idle, because it can take a long time.
|
|
*/
|
|
void nohz_run_idle_balance(int cpu)
|
|
{
|
|
unsigned int flags;
|
|
|
|
flags = atomic_fetch_andnot(NOHZ_NEWILB_KICK, nohz_flags(cpu));
|
|
|
|
/*
|
|
* Update the blocked load only if no SCHED_SOFTIRQ is about to happen
|
|
* (ie NOHZ_STATS_KICK set) and will do the same.
|
|
*/
|
|
if ((flags == NOHZ_NEWILB_KICK) && !need_resched())
|
|
_nohz_idle_balance(cpu_rq(cpu), NOHZ_STATS_KICK);
|
|
}
|
|
|
|
static void nohz_newidle_balance(struct rq *this_rq)
|
|
{
|
|
int this_cpu = this_rq->cpu;
|
|
|
|
/*
|
|
* This CPU doesn't want to be disturbed by scheduler
|
|
* housekeeping
|
|
*/
|
|
if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
|
|
return;
|
|
|
|
/* Will wake up very soon. No time for doing anything else*/
|
|
if (this_rq->avg_idle < sysctl_sched_migration_cost)
|
|
return;
|
|
|
|
/* Don't need to update blocked load of idle CPUs*/
|
|
if (!READ_ONCE(nohz.has_blocked) ||
|
|
time_before(jiffies, READ_ONCE(nohz.next_blocked)))
|
|
return;
|
|
|
|
/*
|
|
* Set the need to trigger ILB in order to update blocked load
|
|
* before entering idle state.
|
|
*/
|
|
atomic_or(NOHZ_NEWILB_KICK, nohz_flags(this_cpu));
|
|
}
|
|
|
|
#else /* !CONFIG_NO_HZ_COMMON */
|
|
static inline void nohz_balancer_kick(struct rq *rq) { }
|
|
|
|
static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline void nohz_newidle_balance(struct rq *this_rq) { }
|
|
#endif /* CONFIG_NO_HZ_COMMON */
|
|
|
|
/*
|
|
* newidle_balance is called by schedule() if this_cpu is about to become
|
|
* idle. Attempts to pull tasks from other CPUs.
|
|
*
|
|
* Returns:
|
|
* < 0 - we released the lock and there are !fair tasks present
|
|
* 0 - failed, no new tasks
|
|
* > 0 - success, new (fair) tasks present
|
|
*/
|
|
static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
|
|
{
|
|
unsigned long next_balance = jiffies + HZ;
|
|
int this_cpu = this_rq->cpu;
|
|
u64 t0, t1, curr_cost = 0;
|
|
struct sched_domain *sd;
|
|
int pulled_task = 0;
|
|
|
|
update_misfit_status(NULL, this_rq);
|
|
|
|
/*
|
|
* There is a task waiting to run. No need to search for one.
|
|
* Return 0; the task will be enqueued when switching to idle.
|
|
*/
|
|
if (this_rq->ttwu_pending)
|
|
return 0;
|
|
|
|
/*
|
|
* We must set idle_stamp _before_ calling idle_balance(), such that we
|
|
* measure the duration of idle_balance() as idle time.
|
|
*/
|
|
this_rq->idle_stamp = rq_clock(this_rq);
|
|
|
|
/*
|
|
* Do not pull tasks towards !active CPUs...
|
|
*/
|
|
if (!cpu_active(this_cpu))
|
|
return 0;
|
|
|
|
/*
|
|
* This is OK, because current is on_cpu, which avoids it being picked
|
|
* for load-balance and preemption/IRQs are still disabled avoiding
|
|
* further scheduler activity on it and we're being very careful to
|
|
* re-start the picking loop.
|
|
*/
|
|
rq_unpin_lock(this_rq, rf);
|
|
|
|
rcu_read_lock();
|
|
sd = rcu_dereference_check_sched_domain(this_rq->sd);
|
|
|
|
if (!READ_ONCE(this_rq->rd->overload) ||
|
|
(sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
|
|
|
|
if (sd)
|
|
update_next_balance(sd, &next_balance);
|
|
rcu_read_unlock();
|
|
|
|
goto out;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
raw_spin_rq_unlock(this_rq);
|
|
|
|
t0 = sched_clock_cpu(this_cpu);
|
|
update_blocked_averages(this_cpu);
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(this_cpu, sd) {
|
|
int continue_balancing = 1;
|
|
u64 domain_cost;
|
|
|
|
update_next_balance(sd, &next_balance);
|
|
|
|
if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost)
|
|
break;
|
|
|
|
if (sd->flags & SD_BALANCE_NEWIDLE) {
|
|
|
|
pulled_task = load_balance(this_cpu, this_rq,
|
|
sd, CPU_NEWLY_IDLE,
|
|
&continue_balancing);
|
|
|
|
t1 = sched_clock_cpu(this_cpu);
|
|
domain_cost = t1 - t0;
|
|
update_newidle_cost(sd, domain_cost);
|
|
|
|
curr_cost += domain_cost;
|
|
t0 = t1;
|
|
}
|
|
|
|
/*
|
|
* Stop searching for tasks to pull if there are
|
|
* now runnable tasks on this rq.
|
|
*/
|
|
if (pulled_task || this_rq->nr_running > 0 ||
|
|
this_rq->ttwu_pending)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
raw_spin_rq_lock(this_rq);
|
|
|
|
if (curr_cost > this_rq->max_idle_balance_cost)
|
|
this_rq->max_idle_balance_cost = curr_cost;
|
|
|
|
/*
|
|
* While browsing the domains, we released the rq lock, a task could
|
|
* have been enqueued in the meantime. Since we're not going idle,
|
|
* pretend we pulled a task.
|
|
*/
|
|
if (this_rq->cfs.h_nr_running && !pulled_task)
|
|
pulled_task = 1;
|
|
|
|
/* Is there a task of a high priority class? */
|
|
if (this_rq->nr_running != this_rq->cfs.h_nr_running)
|
|
pulled_task = -1;
|
|
|
|
out:
|
|
/* Move the next balance forward */
|
|
if (time_after(this_rq->next_balance, next_balance))
|
|
this_rq->next_balance = next_balance;
|
|
|
|
if (pulled_task)
|
|
this_rq->idle_stamp = 0;
|
|
else
|
|
nohz_newidle_balance(this_rq);
|
|
|
|
rq_repin_lock(this_rq, rf);
|
|
|
|
return pulled_task;
|
|
}
|
|
|
|
/*
|
|
* run_rebalance_domains is triggered when needed from the scheduler tick.
|
|
* Also triggered for nohz idle balancing (with nohz_balancing_kick set).
|
|
*/
|
|
static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
|
|
{
|
|
struct rq *this_rq = this_rq();
|
|
enum cpu_idle_type idle = this_rq->idle_balance ?
|
|
CPU_IDLE : CPU_NOT_IDLE;
|
|
|
|
/*
|
|
* If this CPU has a pending nohz_balance_kick, then do the
|
|
* balancing on behalf of the other idle CPUs whose ticks are
|
|
* stopped. Do nohz_idle_balance *before* rebalance_domains to
|
|
* give the idle CPUs a chance to load balance. Else we may
|
|
* load balance only within the local sched_domain hierarchy
|
|
* and abort nohz_idle_balance altogether if we pull some load.
|
|
*/
|
|
if (nohz_idle_balance(this_rq, idle))
|
|
return;
|
|
|
|
/* normal load balance */
|
|
update_blocked_averages(this_rq->cpu);
|
|
rebalance_domains(this_rq, idle);
|
|
}
|
|
|
|
/*
|
|
* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
|
|
*/
|
|
void trigger_load_balance(struct rq *rq)
|
|
{
|
|
/*
|
|
* Don't need to rebalance while attached to NULL domain or
|
|
* runqueue CPU is not active
|
|
*/
|
|
if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
|
|
return;
|
|
|
|
if (time_after_eq(jiffies, rq->next_balance))
|
|
raise_softirq(SCHED_SOFTIRQ);
|
|
|
|
nohz_balancer_kick(rq);
|
|
}
|
|
|
|
static void rq_online_fair(struct rq *rq)
|
|
{
|
|
update_sysctl();
|
|
|
|
update_runtime_enabled(rq);
|
|
}
|
|
|
|
static void rq_offline_fair(struct rq *rq)
|
|
{
|
|
update_sysctl();
|
|
|
|
/* Ensure any throttled groups are reachable by pick_next_task */
|
|
unthrottle_offline_cfs_rqs(rq);
|
|
|
|
/* Ensure that we remove rq contribution to group share: */
|
|
clear_tg_offline_cfs_rqs(rq);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
#ifdef CONFIG_SCHED_CORE
|
|
static inline bool
|
|
__entity_slice_used(struct sched_entity *se, int min_nr_tasks)
|
|
{
|
|
u64 rtime = se->sum_exec_runtime - se->prev_sum_exec_runtime;
|
|
u64 slice = se->slice;
|
|
|
|
return (rtime * min_nr_tasks > slice);
|
|
}
|
|
|
|
#define MIN_NR_TASKS_DURING_FORCEIDLE 2
|
|
static inline void task_tick_core(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
if (!sched_core_enabled(rq))
|
|
return;
|
|
|
|
/*
|
|
* If runqueue has only one task which used up its slice and
|
|
* if the sibling is forced idle, then trigger schedule to
|
|
* give forced idle task a chance.
|
|
*
|
|
* sched_slice() considers only this active rq and it gets the
|
|
* whole slice. But during force idle, we have siblings acting
|
|
* like a single runqueue and hence we need to consider runnable
|
|
* tasks on this CPU and the forced idle CPU. Ideally, we should
|
|
* go through the forced idle rq, but that would be a perf hit.
|
|
* We can assume that the forced idle CPU has at least
|
|
* MIN_NR_TASKS_DURING_FORCEIDLE - 1 tasks and use that to check
|
|
* if we need to give up the CPU.
|
|
*/
|
|
if (rq->core->core_forceidle_count && rq->cfs.nr_running == 1 &&
|
|
__entity_slice_used(&curr->se, MIN_NR_TASKS_DURING_FORCEIDLE))
|
|
resched_curr(rq);
|
|
}
|
|
|
|
/*
|
|
* se_fi_update - Update the cfs_rq->min_vruntime_fi in a CFS hierarchy if needed.
|
|
*/
|
|
static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq,
|
|
bool forceidle)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
if (forceidle) {
|
|
if (cfs_rq->forceidle_seq == fi_seq)
|
|
break;
|
|
cfs_rq->forceidle_seq = fi_seq;
|
|
}
|
|
|
|
cfs_rq->min_vruntime_fi = cfs_rq->min_vruntime;
|
|
}
|
|
}
|
|
|
|
void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
if (p->sched_class != &fair_sched_class)
|
|
return;
|
|
|
|
se_fi_update(se, rq->core->core_forceidle_seq, in_fi);
|
|
}
|
|
|
|
bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
|
|
bool in_fi)
|
|
{
|
|
struct rq *rq = task_rq(a);
|
|
const struct sched_entity *sea = &a->se;
|
|
const struct sched_entity *seb = &b->se;
|
|
struct cfs_rq *cfs_rqa;
|
|
struct cfs_rq *cfs_rqb;
|
|
s64 delta;
|
|
|
|
SCHED_WARN_ON(task_rq(b)->core != rq->core);
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* Find an se in the hierarchy for tasks a and b, such that the se's
|
|
* are immediate siblings.
|
|
*/
|
|
while (sea->cfs_rq->tg != seb->cfs_rq->tg) {
|
|
int sea_depth = sea->depth;
|
|
int seb_depth = seb->depth;
|
|
|
|
if (sea_depth >= seb_depth)
|
|
sea = parent_entity(sea);
|
|
if (sea_depth <= seb_depth)
|
|
seb = parent_entity(seb);
|
|
}
|
|
|
|
se_fi_update(sea, rq->core->core_forceidle_seq, in_fi);
|
|
se_fi_update(seb, rq->core->core_forceidle_seq, in_fi);
|
|
|
|
cfs_rqa = sea->cfs_rq;
|
|
cfs_rqb = seb->cfs_rq;
|
|
#else
|
|
cfs_rqa = &task_rq(a)->cfs;
|
|
cfs_rqb = &task_rq(b)->cfs;
|
|
#endif
|
|
|
|
/*
|
|
* Find delta after normalizing se's vruntime with its cfs_rq's
|
|
* min_vruntime_fi, which would have been updated in prior calls
|
|
* to se_fi_update().
|
|
*/
|
|
delta = (s64)(sea->vruntime - seb->vruntime) +
|
|
(s64)(cfs_rqb->min_vruntime_fi - cfs_rqa->min_vruntime_fi);
|
|
|
|
return delta > 0;
|
|
}
|
|
|
|
static int task_is_throttled_fair(struct task_struct *p, int cpu)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
cfs_rq = task_group(p)->cfs_rq[cpu];
|
|
#else
|
|
cfs_rq = &cpu_rq(cpu)->cfs;
|
|
#endif
|
|
return throttled_hierarchy(cfs_rq);
|
|
}
|
|
#else
|
|
static inline void task_tick_core(struct rq *rq, struct task_struct *curr) {}
|
|
#endif
|
|
|
|
/*
|
|
* scheduler tick hitting a task of our scheduling class.
|
|
*
|
|
* NOTE: This function can be called remotely by the tick offload that
|
|
* goes along full dynticks. Therefore no local assumption can be made
|
|
* and everything must be accessed through the @rq and @curr passed in
|
|
* parameters.
|
|
*/
|
|
static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &curr->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
entity_tick(cfs_rq, se, queued);
|
|
}
|
|
|
|
if (static_branch_unlikely(&sched_numa_balancing))
|
|
task_tick_numa(rq, curr);
|
|
|
|
update_misfit_status(curr, rq);
|
|
update_overutilized_status(task_rq(curr));
|
|
|
|
task_tick_core(rq, curr);
|
|
}
|
|
|
|
/*
|
|
* called on fork with the child task as argument from the parent's context
|
|
* - child not yet on the tasklist
|
|
* - preemption disabled
|
|
*/
|
|
static void task_fork_fair(struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se, *curr;
|
|
struct cfs_rq *cfs_rq;
|
|
struct rq *rq = this_rq();
|
|
struct rq_flags rf;
|
|
|
|
rq_lock(rq, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
cfs_rq = task_cfs_rq(current);
|
|
curr = cfs_rq->curr;
|
|
if (curr)
|
|
update_curr(cfs_rq);
|
|
place_entity(cfs_rq, se, ENQUEUE_INITIAL);
|
|
rq_unlock(rq, &rf);
|
|
}
|
|
|
|
/*
|
|
* Priority of the task has changed. Check to see if we preempt
|
|
* the current task.
|
|
*/
|
|
static void
|
|
prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
|
|
{
|
|
if (!task_on_rq_queued(p))
|
|
return;
|
|
|
|
if (rq->cfs.nr_running == 1)
|
|
return;
|
|
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (task_current(rq, p)) {
|
|
if (p->prio > oldprio)
|
|
resched_curr(rq);
|
|
} else
|
|
wakeup_preempt(rq, p, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* Propagate the changes of the sched_entity across the tg tree to make it
|
|
* visible to the root
|
|
*/
|
|
static void propagate_entity_cfs_rq(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
return;
|
|
|
|
if (!throttled_hierarchy(cfs_rq))
|
|
list_add_leaf_cfs_rq(cfs_rq);
|
|
|
|
/* Start to propagate at parent */
|
|
se = se->parent;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
|
|
update_load_avg(cfs_rq, se, UPDATE_TG);
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
|
|
if (!throttled_hierarchy(cfs_rq))
|
|
list_add_leaf_cfs_rq(cfs_rq);
|
|
}
|
|
}
|
|
#else
|
|
static void propagate_entity_cfs_rq(struct sched_entity *se) { }
|
|
#endif
|
|
|
|
static void detach_entity_cfs_rq(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* In case the task sched_avg hasn't been attached:
|
|
* - A forked task which hasn't been woken up by wake_up_new_task().
|
|
* - A task which has been woken up by try_to_wake_up() but is
|
|
* waiting for actually being woken up by sched_ttwu_pending().
|
|
*/
|
|
if (!se->avg.last_update_time)
|
|
return;
|
|
#endif
|
|
|
|
/* Catch up with the cfs_rq and remove our load when we leave */
|
|
update_load_avg(cfs_rq, se, 0);
|
|
detach_entity_load_avg(cfs_rq, se);
|
|
update_tg_load_avg(cfs_rq);
|
|
propagate_entity_cfs_rq(se);
|
|
}
|
|
|
|
static void attach_entity_cfs_rq(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
/* Synchronize entity with its cfs_rq */
|
|
update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
|
|
attach_entity_load_avg(cfs_rq, se);
|
|
update_tg_load_avg(cfs_rq);
|
|
propagate_entity_cfs_rq(se);
|
|
}
|
|
|
|
static void detach_task_cfs_rq(struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
detach_entity_cfs_rq(se);
|
|
}
|
|
|
|
static void attach_task_cfs_rq(struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
attach_entity_cfs_rq(se);
|
|
}
|
|
|
|
static void switched_from_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
detach_task_cfs_rq(p);
|
|
}
|
|
|
|
static void switched_to_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
attach_task_cfs_rq(p);
|
|
|
|
if (task_on_rq_queued(p)) {
|
|
/*
|
|
* We were most likely switched from sched_rt, so
|
|
* kick off the schedule if running, otherwise just see
|
|
* if we can still preempt the current task.
|
|
*/
|
|
if (task_current(rq, p))
|
|
resched_curr(rq);
|
|
else
|
|
wakeup_preempt(rq, p, 0);
|
|
}
|
|
}
|
|
|
|
/* Account for a task changing its policy or group.
|
|
*
|
|
* This routine is mostly called to set cfs_rq->curr field when a task
|
|
* migrates between groups/classes.
|
|
*/
|
|
static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (task_on_rq_queued(p)) {
|
|
/*
|
|
* Move the next running task to the front of the list, so our
|
|
* cfs_tasks list becomes MRU one.
|
|
*/
|
|
list_move(&se->group_node, &rq->cfs_tasks);
|
|
}
|
|
#endif
|
|
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
set_next_entity(cfs_rq, se);
|
|
/* ensure bandwidth has been allocated on our new cfs_rq */
|
|
account_cfs_rq_runtime(cfs_rq, 0);
|
|
}
|
|
}
|
|
|
|
void init_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
cfs_rq->tasks_timeline = RB_ROOT_CACHED;
|
|
u64_u32_store(cfs_rq->min_vruntime, (u64)(-(1LL << 20)));
|
|
#ifdef CONFIG_SMP
|
|
raw_spin_lock_init(&cfs_rq->removed.lock);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static void task_change_group_fair(struct task_struct *p)
|
|
{
|
|
/*
|
|
* We couldn't detach or attach a forked task which
|
|
* hasn't been woken up by wake_up_new_task().
|
|
*/
|
|
if (READ_ONCE(p->__state) == TASK_NEW)
|
|
return;
|
|
|
|
detach_task_cfs_rq(p);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/* Tell se's cfs_rq has been changed -- migrated */
|
|
p->se.avg.last_update_time = 0;
|
|
#endif
|
|
set_task_rq(p, task_cpu(p));
|
|
attach_task_cfs_rq(p);
|
|
}
|
|
|
|
void free_fair_sched_group(struct task_group *tg)
|
|
{
|
|
int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
if (tg->cfs_rq)
|
|
kfree(tg->cfs_rq[i]);
|
|
if (tg->se)
|
|
kfree(tg->se[i]);
|
|
}
|
|
|
|
kfree(tg->cfs_rq);
|
|
kfree(tg->se);
|
|
}
|
|
|
|
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
|
|
{
|
|
struct sched_entity *se;
|
|
struct cfs_rq *cfs_rq;
|
|
int i;
|
|
|
|
tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(cfs_rq), GFP_KERNEL);
|
|
if (!tg->cfs_rq)
|
|
goto err;
|
|
tg->se = kcalloc(nr_cpu_ids, sizeof(se), GFP_KERNEL);
|
|
if (!tg->se)
|
|
goto err;
|
|
|
|
tg->shares = NICE_0_LOAD;
|
|
|
|
init_cfs_bandwidth(tg_cfs_bandwidth(tg), tg_cfs_bandwidth(parent));
|
|
|
|
for_each_possible_cpu(i) {
|
|
cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
if (!cfs_rq)
|
|
goto err;
|
|
|
|
se = kzalloc_node(sizeof(struct sched_entity_stats),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
if (!se)
|
|
goto err_free_rq;
|
|
|
|
init_cfs_rq(cfs_rq);
|
|
init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
|
|
init_entity_runnable_average(se);
|
|
}
|
|
|
|
return 1;
|
|
|
|
err_free_rq:
|
|
kfree(cfs_rq);
|
|
err:
|
|
return 0;
|
|
}
|
|
|
|
void online_fair_sched_group(struct task_group *tg)
|
|
{
|
|
struct sched_entity *se;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
rq = cpu_rq(i);
|
|
se = tg->se[i];
|
|
rq_lock_irq(rq, &rf);
|
|
update_rq_clock(rq);
|
|
attach_entity_cfs_rq(se);
|
|
sync_throttle(tg, i);
|
|
rq_unlock_irq(rq, &rf);
|
|
}
|
|
}
|
|
|
|
void unregister_fair_sched_group(struct task_group *tg)
|
|
{
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
int cpu;
|
|
|
|
destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
if (tg->se[cpu])
|
|
remove_entity_load_avg(tg->se[cpu]);
|
|
|
|
/*
|
|
* Only empty task groups can be destroyed; so we can speculatively
|
|
* check on_list without danger of it being re-added.
|
|
*/
|
|
if (!tg->cfs_rq[cpu]->on_list)
|
|
continue;
|
|
|
|
rq = cpu_rq(cpu);
|
|
|
|
raw_spin_rq_lock_irqsave(rq, flags);
|
|
list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
|
|
raw_spin_rq_unlock_irqrestore(rq, flags);
|
|
}
|
|
}
|
|
|
|
void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se, int cpu,
|
|
struct sched_entity *parent)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
cfs_rq->tg = tg;
|
|
cfs_rq->rq = rq;
|
|
init_cfs_rq_runtime(cfs_rq);
|
|
|
|
tg->cfs_rq[cpu] = cfs_rq;
|
|
tg->se[cpu] = se;
|
|
|
|
/* se could be NULL for root_task_group */
|
|
if (!se)
|
|
return;
|
|
|
|
if (!parent) {
|
|
se->cfs_rq = &rq->cfs;
|
|
se->depth = 0;
|
|
} else {
|
|
se->cfs_rq = parent->my_q;
|
|
se->depth = parent->depth + 1;
|
|
}
|
|
|
|
se->my_q = cfs_rq;
|
|
/* guarantee group entities always have weight */
|
|
update_load_set(&se->load, NICE_0_LOAD);
|
|
se->parent = parent;
|
|
}
|
|
|
|
static DEFINE_MUTEX(shares_mutex);
|
|
|
|
static int __sched_group_set_shares(struct task_group *tg, unsigned long shares)
|
|
{
|
|
int i;
|
|
|
|
lockdep_assert_held(&shares_mutex);
|
|
|
|
/*
|
|
* We can't change the weight of the root cgroup.
|
|
*/
|
|
if (!tg->se[0])
|
|
return -EINVAL;
|
|
|
|
shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
|
|
|
|
if (tg->shares == shares)
|
|
return 0;
|
|
|
|
tg->shares = shares;
|
|
for_each_possible_cpu(i) {
|
|
struct rq *rq = cpu_rq(i);
|
|
struct sched_entity *se = tg->se[i];
|
|
struct rq_flags rf;
|
|
|
|
/* Propagate contribution to hierarchy */
|
|
rq_lock_irqsave(rq, &rf);
|
|
update_rq_clock(rq);
|
|
for_each_sched_entity(se) {
|
|
update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
|
|
update_cfs_group(se);
|
|
}
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int sched_group_set_shares(struct task_group *tg, unsigned long shares)
|
|
{
|
|
int ret;
|
|
|
|
mutex_lock(&shares_mutex);
|
|
if (tg_is_idle(tg))
|
|
ret = -EINVAL;
|
|
else
|
|
ret = __sched_group_set_shares(tg, shares);
|
|
mutex_unlock(&shares_mutex);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int sched_group_set_idle(struct task_group *tg, long idle)
|
|
{
|
|
int i;
|
|
|
|
if (tg == &root_task_group)
|
|
return -EINVAL;
|
|
|
|
if (idle < 0 || idle > 1)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&shares_mutex);
|
|
|
|
if (tg->idle == idle) {
|
|
mutex_unlock(&shares_mutex);
|
|
return 0;
|
|
}
|
|
|
|
tg->idle = idle;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct rq *rq = cpu_rq(i);
|
|
struct sched_entity *se = tg->se[i];
|
|
struct cfs_rq *parent_cfs_rq, *grp_cfs_rq = tg->cfs_rq[i];
|
|
bool was_idle = cfs_rq_is_idle(grp_cfs_rq);
|
|
long idle_task_delta;
|
|
struct rq_flags rf;
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
|
|
grp_cfs_rq->idle = idle;
|
|
if (WARN_ON_ONCE(was_idle == cfs_rq_is_idle(grp_cfs_rq)))
|
|
goto next_cpu;
|
|
|
|
if (se->on_rq) {
|
|
parent_cfs_rq = cfs_rq_of(se);
|
|
if (cfs_rq_is_idle(grp_cfs_rq))
|
|
parent_cfs_rq->idle_nr_running++;
|
|
else
|
|
parent_cfs_rq->idle_nr_running--;
|
|
}
|
|
|
|
idle_task_delta = grp_cfs_rq->h_nr_running -
|
|
grp_cfs_rq->idle_h_nr_running;
|
|
if (!cfs_rq_is_idle(grp_cfs_rq))
|
|
idle_task_delta *= -1;
|
|
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
if (!se->on_rq)
|
|
break;
|
|
|
|
cfs_rq->idle_h_nr_running += idle_task_delta;
|
|
|
|
/* Already accounted at parent level and above. */
|
|
if (cfs_rq_is_idle(cfs_rq))
|
|
break;
|
|
}
|
|
|
|
next_cpu:
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
/* Idle groups have minimum weight. */
|
|
if (tg_is_idle(tg))
|
|
__sched_group_set_shares(tg, scale_load(WEIGHT_IDLEPRIO));
|
|
else
|
|
__sched_group_set_shares(tg, NICE_0_LOAD);
|
|
|
|
mutex_unlock(&shares_mutex);
|
|
return 0;
|
|
}
|
|
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
|
|
static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
|
|
{
|
|
struct sched_entity *se = &task->se;
|
|
unsigned int rr_interval = 0;
|
|
|
|
/*
|
|
* Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
|
|
* idle runqueue:
|
|
*/
|
|
if (rq->cfs.load.weight)
|
|
rr_interval = NS_TO_JIFFIES(se->slice);
|
|
|
|
return rr_interval;
|
|
}
|
|
|
|
/*
|
|
* All the scheduling class methods:
|
|
*/
|
|
DEFINE_SCHED_CLASS(fair) = {
|
|
|
|
.enqueue_task = enqueue_task_fair,
|
|
.dequeue_task = dequeue_task_fair,
|
|
.yield_task = yield_task_fair,
|
|
.yield_to_task = yield_to_task_fair,
|
|
|
|
.wakeup_preempt = check_preempt_wakeup_fair,
|
|
|
|
.pick_next_task = __pick_next_task_fair,
|
|
.put_prev_task = put_prev_task_fair,
|
|
.set_next_task = set_next_task_fair,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.balance = balance_fair,
|
|
.pick_task = pick_task_fair,
|
|
.select_task_rq = select_task_rq_fair,
|
|
.migrate_task_rq = migrate_task_rq_fair,
|
|
|
|
.rq_online = rq_online_fair,
|
|
.rq_offline = rq_offline_fair,
|
|
|
|
.task_dead = task_dead_fair,
|
|
.set_cpus_allowed = set_cpus_allowed_common,
|
|
#endif
|
|
|
|
.task_tick = task_tick_fair,
|
|
.task_fork = task_fork_fair,
|
|
|
|
.prio_changed = prio_changed_fair,
|
|
.switched_from = switched_from_fair,
|
|
.switched_to = switched_to_fair,
|
|
|
|
.get_rr_interval = get_rr_interval_fair,
|
|
|
|
.update_curr = update_curr_fair,
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
.task_change_group = task_change_group_fair,
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_CORE
|
|
.task_is_throttled = task_is_throttled_fair,
|
|
#endif
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK
|
|
.uclamp_enabled = 1,
|
|
#endif
|
|
};
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
void print_cfs_stats(struct seq_file *m, int cpu)
|
|
{
|
|
struct cfs_rq *cfs_rq, *pos;
|
|
|
|
rcu_read_lock();
|
|
for_each_leaf_cfs_rq_safe(cpu_rq(cpu), cfs_rq, pos)
|
|
print_cfs_rq(m, cpu, cfs_rq);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
void show_numa_stats(struct task_struct *p, struct seq_file *m)
|
|
{
|
|
int node;
|
|
unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0;
|
|
struct numa_group *ng;
|
|
|
|
rcu_read_lock();
|
|
ng = rcu_dereference(p->numa_group);
|
|
for_each_online_node(node) {
|
|
if (p->numa_faults) {
|
|
tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)];
|
|
tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)];
|
|
}
|
|
if (ng) {
|
|
gsf = ng->faults[task_faults_idx(NUMA_MEM, node, 0)],
|
|
gpf = ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
|
|
}
|
|
print_numa_stats(m, node, tsf, tpf, gsf, gpf);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
#endif /* CONFIG_SCHED_DEBUG */
|
|
|
|
__init void init_sched_fair_class(void)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
zalloc_cpumask_var_node(&per_cpu(load_balance_mask, i), GFP_KERNEL, cpu_to_node(i));
|
|
zalloc_cpumask_var_node(&per_cpu(select_rq_mask, i), GFP_KERNEL, cpu_to_node(i));
|
|
zalloc_cpumask_var_node(&per_cpu(should_we_balance_tmpmask, i),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
INIT_CSD(&cpu_rq(i)->cfsb_csd, __cfsb_csd_unthrottle, cpu_rq(i));
|
|
INIT_LIST_HEAD(&cpu_rq(i)->cfsb_csd_list);
|
|
#endif
|
|
}
|
|
|
|
open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
nohz.next_balance = jiffies;
|
|
nohz.next_blocked = jiffies;
|
|
zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
|
|
#endif
|
|
#endif /* SMP */
|
|
|
|
}
|