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sched/psi: Rename existing poll members in preparation

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Renaming in PSI implementation to make a clear distinction between
privileged and unprivileged triggers code to be implemented in the
next patch.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-3-cerasuolodomenico@gmail.com
This commit is contained in:
Domenico Cerasuolo 2023-03-30 12:54:16 +02:00 committed by Peter Zijlstra
parent 7fab21fa0d
commit 65457b74aa
2 changed files with 98 additions and 97 deletions
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32
include/linux/psi_types.h
View file

@ -175,26 +175,26 @@ struct psi_group {
u64 total[NR_PSI_AGGREGATORS][NR_PSI_STATES - 1];
unsigned long avg[NR_PSI_STATES - 1][3];
/* Monitor work control */
struct task_struct __rcu *poll_task;
struct timer_list poll_timer;
wait_queue_head_t poll_wait;
atomic_t poll_wakeup;
atomic_t poll_scheduled;
/* Monitor RT polling work control */
struct task_struct __rcu *rtpoll_task;
struct timer_list rtpoll_timer;
wait_queue_head_t rtpoll_wait;
atomic_t rtpoll_wakeup;
atomic_t rtpoll_scheduled;
/* Protects data used by the monitor */
struct mutex trigger_lock;
struct mutex rtpoll_trigger_lock;
/* Configured polling triggers */
struct list_head triggers;
u32 nr_triggers[NR_PSI_STATES - 1];
u32 poll_states;
u64 poll_min_period;
/* Configured RT polling triggers */
struct list_head rtpoll_triggers;
u32 rtpoll_nr_triggers[NR_PSI_STATES - 1];
u32 rtpoll_states;
u64 rtpoll_min_period;
/* Total stall times at the start of monitor activation */
u64 polling_total[NR_PSI_STATES - 1];
u64 polling_next_update;
u64 polling_until;
/* Total stall times at the start of RT polling monitor activation */
u64 rtpoll_total[NR_PSI_STATES - 1];
u64 rtpoll_next_update;
u64 rtpoll_until;
};
#else /* CONFIG_PSI */

163
kernel/sched/psi.c
View file

@ -189,14 +189,14 @@ static void group_init(struct psi_group *group)
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
mutex_init(&group->avgs_lock);
/* Init trigger-related members */
atomic_set(&group->poll_scheduled, 0);
mutex_init(&group->trigger_lock);
INIT_LIST_HEAD(&group->triggers);
group->poll_min_period = U32_MAX;
group->polling_next_update = ULLONG_MAX;
init_waitqueue_head(&group->poll_wait);
timer_setup(&group->poll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->poll_task, NULL);
atomic_set(&group->rtpoll_scheduled, 0);
mutex_init(&group->rtpoll_trigger_lock);
INIT_LIST_HEAD(&group->rtpoll_triggers);
group->rtpoll_min_period = U32_MAX;
group->rtpoll_next_update = ULLONG_MAX;
init_waitqueue_head(&group->rtpoll_wait);
timer_setup(&group->rtpoll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->rtpoll_task, NULL);
}
void __init psi_init(void)
@ -440,11 +440,11 @@ static u64 update_triggers(struct psi_group *group, u64 now)
* On subsequent updates, calculate growth deltas and let
* watchers know when their specified thresholds are exceeded.
*/
list_for_each_entry(t, &group->triggers, node) {
list_for_each_entry(t, &group->rtpoll_triggers, node) {
u64 growth;
bool new_stall;
new_stall = group->polling_total[t->state] != total[t->state];
new_stall = group->rtpoll_total[t->state] != total[t->state];
/* Check for stall activity or a previous threshold breach */
if (!new_stall && !t->pending_event)
@ -486,10 +486,10 @@ static u64 update_triggers(struct psi_group *group, u64 now)
}
if (update_total)
memcpy(group->polling_total, total,
sizeof(group->polling_total));
memcpy(group->rtpoll_total, total,
sizeof(group->rtpoll_total));
return now + group->poll_min_period;
return now + group->rtpoll_min_period;
}
static u64 update_averages(struct psi_group *group, u64 now)
@ -582,53 +582,53 @@ static void init_triggers(struct psi_group *group, u64 now)
{
struct psi_trigger *t;
list_for_each_entry(t, &group->triggers, node)
list_for_each_entry(t, &group->rtpoll_triggers, node)
window_reset(&t->win, now,
group->total[PSI_POLL][t->state], 0);
memcpy(group->polling_total, group->total[PSI_POLL],
sizeof(group->polling_total));
group->polling_next_update = now + group->poll_min_period;
memcpy(group->rtpoll_total, group->total[PSI_POLL],
sizeof(group->rtpoll_total));
group->rtpoll_next_update = now + group->rtpoll_min_period;
}
/* Schedule polling if it's not already scheduled or forced. */
static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay,
static void psi_schedule_rtpoll_work(struct psi_group *group, unsigned long delay,
bool force)
{
struct task_struct *task;
/*
* atomic_xchg should be called even when !force to provide a
* full memory barrier (see the comment inside psi_poll_work).
* full memory barrier (see the comment inside psi_rtpoll_work).
*/
if (atomic_xchg(&group->poll_scheduled, 1) && !force)
if (atomic_xchg(&group->rtpoll_scheduled, 1) && !force)
return;
rcu_read_lock();
task = rcu_dereference(group->poll_task);
task = rcu_dereference(group->rtpoll_task);
/*
* kworker might be NULL in case psi_trigger_destroy races with
* psi_task_change (hotpath) which can't use locks
*/
if (likely(task))
mod_timer(&group->poll_timer, jiffies + delay);
mod_timer(&group->rtpoll_timer, jiffies + delay);
else
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
rcu_read_unlock();
}
static void psi_poll_work(struct psi_group *group)
static void psi_rtpoll_work(struct psi_group *group)
{
bool force_reschedule = false;
u32 changed_states;
u64 now;
mutex_lock(&group->trigger_lock);
mutex_lock(&group->rtpoll_trigger_lock);
now = sched_clock();
if (now > group->polling_until) {
if (now > group->rtpoll_until) {
/*
* We are either about to start or might stop polling if no
* state change was recorded. Resetting poll_scheduled leaves
@ -638,7 +638,7 @@ static void psi_poll_work(struct psi_group *group)
* should be negligible and polling_next_update still keeps
* updates correctly on schedule.
*/
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
/*
* A task change can race with the poll worker that is supposed to
* report on it. To avoid missing events, ensure ordering between
@ -667,9 +667,9 @@ static void psi_poll_work(struct psi_group *group)
collect_percpu_times(group, PSI_POLL, &changed_states);
if (changed_states & group->poll_states) {
if (changed_states & group->rtpoll_states) {
/* Initialize trigger windows when entering polling mode */
if (now > group->polling_until)
if (now > group->rtpoll_until)
init_triggers(group, now);
/*
@ -677,50 +677,50 @@ static void psi_poll_work(struct psi_group *group)
* minimum tracking window as long as monitor states are
* changing.
*/
group->polling_until = now +
group->poll_min_period * UPDATES_PER_WINDOW;
group->rtpoll_until = now +
group->rtpoll_min_period * UPDATES_PER_WINDOW;
}
if (now > group->polling_until) {
group->polling_next_update = ULLONG_MAX;
if (now > group->rtpoll_until) {
group->rtpoll_next_update = ULLONG_MAX;
goto out;
}
if (now >= group->polling_next_update)
group->polling_next_update = update_triggers(group, now);
if (now >= group->rtpoll_next_update)
group->rtpoll_next_update = update_triggers(group, now);
psi_schedule_poll_work(group,
nsecs_to_jiffies(group->polling_next_update - now) + 1,
psi_schedule_rtpoll_work(group,
nsecs_to_jiffies(group->rtpoll_next_update - now) + 1,
force_reschedule);
out:
mutex_unlock(&group->trigger_lock);
mutex_unlock(&group->rtpoll_trigger_lock);
}
static int psi_poll_worker(void *data)
static int psi_rtpoll_worker(void *data)
{
struct psi_group *group = (struct psi_group *)data;
sched_set_fifo_low(current);
while (true) {
wait_event_interruptible(group->poll_wait,
atomic_cmpxchg(&group->poll_wakeup, 1, 0) ||
wait_event_interruptible(group->rtpoll_wait,
atomic_cmpxchg(&group->rtpoll_wakeup, 1, 0) ||
kthread_should_stop());
if (kthread_should_stop())
break;
psi_poll_work(group);
psi_rtpoll_work(group);
}
return 0;
}
static void poll_timer_fn(struct timer_list *t)
{
struct psi_group *group = from_timer(group, t, poll_timer);
struct psi_group *group = from_timer(group, t, rtpoll_timer);
atomic_set(&group->poll_wakeup, 1);
wake_up_interruptible(&group->poll_wait);
atomic_set(&group->rtpoll_wakeup, 1);
wake_up_interruptible(&group->rtpoll_wait);
}
static void record_times(struct psi_group_cpu *groupc, u64 now)
@ -851,8 +851,8 @@ static void psi_group_change(struct psi_group *group, int cpu,
write_seqcount_end(&groupc->seq);
if (state_mask & group->poll_states)
psi_schedule_poll_work(group, 1, false);
if (state_mask & group->rtpoll_states)
psi_schedule_rtpoll_work(group, 1, false);
if (wake_clock && !delayed_work_pending(&group->avgs_work))
schedule_delayed_work(&group->avgs_work, PSI_FREQ);
@ -1005,8 +1005,8 @@ void psi_account_irqtime(struct task_struct *task, u32 delta)
write_seqcount_end(&groupc->seq);
if (group->poll_states & (1 << PSI_IRQ_FULL))
psi_schedule_poll_work(group, 1, false);
if (group->rtpoll_states & (1 << PSI_IRQ_FULL))
psi_schedule_rtpoll_work(group, 1, false);
} while ((group = group->parent));
}
#endif
@ -1101,7 +1101,7 @@ void psi_cgroup_free(struct cgroup *cgroup)
cancel_delayed_work_sync(&cgroup->psi->avgs_work);
free_percpu(cgroup->psi->pcpu);
/* All triggers must be removed by now */
WARN_ONCE(cgroup->psi->poll_states, "psi: trigger leak\n");
WARN_ONCE(cgroup->psi->rtpoll_states, "psi: trigger leak\n");
kfree(cgroup->psi);
}
@ -1302,29 +1302,29 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
init_waitqueue_head(&t->event_wait);
t->pending_event = false;
mutex_lock(&group->trigger_lock);
mutex_lock(&group->rtpoll_trigger_lock);
if (!rcu_access_pointer(group->poll_task)) {
if (!rcu_access_pointer(group->rtpoll_task)) {
struct task_struct *task;
task = kthread_create(psi_poll_worker, group, "psimon");
task = kthread_create(psi_rtpoll_worker, group, "psimon");
if (IS_ERR(task)) {
kfree(t);
mutex_unlock(&group->trigger_lock);
mutex_unlock(&group->rtpoll_trigger_lock);
return ERR_CAST(task);
}
atomic_set(&group->poll_wakeup, 0);
atomic_set(&group->rtpoll_wakeup, 0);
wake_up_process(task);
rcu_assign_pointer(group->poll_task, task);
rcu_assign_pointer(group->rtpoll_task, task);
}
list_add(&t->node, &group->triggers);
group->poll_min_period = min(group->poll_min_period,
list_add(&t->node, &group->rtpoll_triggers);
group->rtpoll_min_period = min(group->rtpoll_min_period,
div_u64(t->win.size, UPDATES_PER_WINDOW));
group->nr_triggers[t->state]++;
group->poll_states |= (1 << t->state);
group->rtpoll_nr_triggers[t->state]++;
group->rtpoll_states |= (1 << t->state);
mutex_unlock(&group->trigger_lock);
mutex_unlock(&group->rtpoll_trigger_lock);
return t;
}
@ -1349,51 +1349,52 @@ void psi_trigger_destroy(struct psi_trigger *t)
*/
wake_up_pollfree(&t->event_wait);
mutex_lock(&group->trigger_lock);
mutex_lock(&group->rtpoll_trigger_lock);
if (!list_empty(&t->node)) {
struct psi_trigger *tmp;
u64 period = ULLONG_MAX;
list_del(&t->node);
group->nr_triggers[t->state]--;
if (!group->nr_triggers[t->state])
group->poll_states &= ~(1 << t->state);
group->rtpoll_nr_triggers[t->state]--;
if (!group->rtpoll_nr_triggers[t->state])
group->rtpoll_states &= ~(1 << t->state);
/* reset min update period for the remaining triggers */
list_for_each_entry(tmp, &group->triggers, node)
list_for_each_entry(tmp, &group->rtpoll_triggers, node)
period = min(period, div_u64(tmp->win.size,
UPDATES_PER_WINDOW));
group->poll_min_period = period;
/* Destroy poll_task when the last trigger is destroyed */
if (group->poll_states == 0) {
group->polling_until = 0;
group->rtpoll_min_period = period;
/* Destroy rtpoll_task when the last trigger is destroyed */
if (group->rtpoll_states == 0) {
group->rtpoll_until = 0;
task_to_destroy = rcu_dereference_protected(
group->poll_task,
lockdep_is_held(&group->trigger_lock));
rcu_assign_pointer(group->poll_task, NULL);
del_timer(&group->poll_timer);
group->rtpoll_task,
lockdep_is_held(&group->rtpoll_trigger_lock));
rcu_assign_pointer(group->rtpoll_task, NULL);
del_timer(&group->rtpoll_timer);
}
}
mutex_unlock(&group->trigger_lock);
mutex_unlock(&group->rtpoll_trigger_lock);
/*
* Wait for psi_schedule_poll_work RCU to complete its read-side
* Wait for psi_schedule_rtpoll_work RCU to complete its read-side
* critical section before destroying the trigger and optionally the
* poll_task.
* rtpoll_task.
*/
synchronize_rcu();
/*
* Stop kthread 'psimon' after releasing trigger_lock to prevent a
* deadlock while waiting for psi_poll_work to acquire trigger_lock
* Stop kthread 'psimon' after releasing rtpoll_trigger_lock to prevent
* a deadlock while waiting for psi_rtpoll_work to acquire
* rtpoll_trigger_lock
*/
if (task_to_destroy) {
/*
* After the RCU grace period has expired, the worker
* can no longer be found through group->poll_task.
* can no longer be found through group->rtpoll_task.
*/
kthread_stop(task_to_destroy);
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
}
kfree(t);
}