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lib/percpu_counter: Convert to hotplug state machine

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Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-5-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior 2016-11-03 15:50:00 +01:00 committed by Thomas Gleixner
parent 308167fcb3
commit 5588f5afb4
2 changed files with 15 additions and 11 deletions
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1
include/linux/cpuhotplug.h
View file

@ -33,6 +33,7 @@ enum cpuhp_state {
CPUHP_FS_BUFF_DEAD,
CPUHP_PRINTK_DEAD,
CPUHP_MM_MEMCQ_DEAD,
CPUHP_PERCPU_CNT_DEAD,
CPUHP_WORKQUEUE_PREP,
CPUHP_POWER_NUMA_PREPARE,
CPUHP_HRTIMERS_PREPARE,

25
lib/percpu_counter.c
View file

@ -158,25 +158,21 @@ EXPORT_SYMBOL(percpu_counter_destroy);
int percpu_counter_batch __read_mostly = 32;
EXPORT_SYMBOL(percpu_counter_batch);
static void compute_batch_value(void)
static int compute_batch_value(unsigned int cpu)
{
int nr = num_online_cpus();
percpu_counter_batch = max(32, nr*2);
return 0;
}
static int percpu_counter_hotcpu_callback(struct notifier_block *nb,
unsigned long action, void *hcpu)
static int percpu_counter_cpu_dead(unsigned int cpu)
{
#ifdef CONFIG_HOTPLUG_CPU
unsigned int cpu;
struct percpu_counter *fbc;
compute_batch_value();
if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
return NOTIFY_OK;
compute_batch_value(cpu);
cpu = (unsigned long)hcpu;
spin_lock_irq(&percpu_counters_lock);
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
@ -190,7 +186,7 @@ static int percpu_counter_hotcpu_callback(struct notifier_block *nb,
}
spin_unlock_irq(&percpu_counters_lock);
#endif
return NOTIFY_OK;
return 0;
}
/*
@ -222,8 +218,15 @@ EXPORT_SYMBOL(__percpu_counter_compare);
static int __init percpu_counter_startup(void)
{
compute_batch_value();
hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
int ret;
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "lib/percpu_cnt:online",
compute_batch_value, NULL);
WARN_ON(ret < 0);
ret = cpuhp_setup_state_nocalls(CPUHP_PERCPU_CNT_DEAD,
"lib/percpu_cnt:dead", NULL,
percpu_counter_cpu_dead);
WARN_ON(ret < 0);
return 0;
}
module_init(percpu_counter_startup);