1 // SPDX-License-Identifier: GPL-2.0
3 * Pressure stall information for CPU, memory and IO
5 * Copyright (c) 2018 Facebook, Inc.
6 * Author: Johannes Weiner <hannes@cmpxchg.org>
8 * Polling support by Suren Baghdasaryan <surenb@google.com>
9 * Copyright (c) 2018 Google, Inc.
11 * When CPU, memory and IO are contended, tasks experience delays that
12 * reduce throughput and introduce latencies into the workload. Memory
13 * and IO contention, in addition, can cause a full loss of forward
14 * progress in which the CPU goes idle.
16 * This code aggregates individual task delays into resource pressure
17 * metrics that indicate problems with both workload health and
18 * resource utilization.
22 * The time in which a task can execute on a CPU is our baseline for
23 * productivity. Pressure expresses the amount of time in which this
24 * potential cannot be realized due to resource contention.
26 * This concept of productivity has two components: the workload and
27 * the CPU. To measure the impact of pressure on both, we define two
28 * contention states for a resource: SOME and FULL.
30 * In the SOME state of a given resource, one or more tasks are
31 * delayed on that resource. This affects the workload's ability to
32 * perform work, but the CPU may still be executing other tasks.
34 * In the FULL state of a given resource, all non-idle tasks are
35 * delayed on that resource such that nobody is advancing and the CPU
36 * goes idle. This leaves both workload and CPU unproductive.
38 * SOME = nr_delayed_tasks != 0
39 * FULL = nr_delayed_tasks != 0 && nr_productive_tasks == 0
41 * What it means for a task to be productive is defined differently
42 * for each resource. For IO, productive means a running task. For
43 * memory, productive means a running task that isn't a reclaimer. For
44 * CPU, productive means an oncpu task.
46 * Naturally, the FULL state doesn't exist for the CPU resource at the
47 * system level, but exist at the cgroup level. At the cgroup level,
48 * FULL means all non-idle tasks in the cgroup are delayed on the CPU
49 * resource which is being used by others outside of the cgroup or
50 * throttled by the cgroup cpu.max configuration.
52 * The percentage of wallclock time spent in those compound stall
53 * states gives pressure numbers between 0 and 100 for each resource,
54 * where the SOME percentage indicates workload slowdowns and the FULL
55 * percentage indicates reduced CPU utilization:
57 * %SOME = time(SOME) / period
58 * %FULL = time(FULL) / period
62 * The more tasks and available CPUs there are, the more work can be
63 * performed concurrently. This means that the potential that can go
64 * unrealized due to resource contention *also* scales with non-idle
67 * Consider a scenario where 257 number crunching tasks are trying to
68 * run concurrently on 256 CPUs. If we simply aggregated the task
69 * states, we would have to conclude a CPU SOME pressure number of
70 * 100%, since *somebody* is waiting on a runqueue at all
71 * times. However, that is clearly not the amount of contention the
72 * workload is experiencing: only one out of 256 possible execution
73 * threads will be contended at any given time, or about 0.4%.
75 * Conversely, consider a scenario of 4 tasks and 4 CPUs where at any
76 * given time *one* of the tasks is delayed due to a lack of memory.
77 * Again, looking purely at the task state would yield a memory FULL
78 * pressure number of 0%, since *somebody* is always making forward
79 * progress. But again this wouldn't capture the amount of execution
80 * potential lost, which is 1 out of 4 CPUs, or 25%.
82 * To calculate wasted potential (pressure) with multiple processors,
83 * we have to base our calculation on the number of non-idle tasks in
84 * conjunction with the number of available CPUs, which is the number
85 * of potential execution threads. SOME becomes then the proportion of
86 * delayed tasks to possible threads, and FULL is the share of possible
87 * threads that are unproductive due to delays:
89 * threads = min(nr_nonidle_tasks, nr_cpus)
90 * SOME = min(nr_delayed_tasks / threads, 1)
91 * FULL = (threads - min(nr_productive_tasks, threads)) / threads
93 * For the 257 number crunchers on 256 CPUs, this yields:
95 * threads = min(257, 256)
96 * SOME = min(1 / 256, 1) = 0.4%
97 * FULL = (256 - min(256, 256)) / 256 = 0%
99 * For the 1 out of 4 memory-delayed tasks, this yields:
101 * threads = min(4, 4)
102 * SOME = min(1 / 4, 1) = 25%
103 * FULL = (4 - min(3, 4)) / 4 = 25%
105 * [ Substitute nr_cpus with 1, and you can see that it's a natural
106 * extension of the single-CPU model. ]
110 * To assess the precise time spent in each such state, we would have
111 * to freeze the system on task changes and start/stop the state
112 * clocks accordingly. Obviously that doesn't scale in practice.
114 * Because the scheduler aims to distribute the compute load evenly
115 * among the available CPUs, we can track task state locally to each
116 * CPU and, at much lower frequency, extrapolate the global state for
117 * the cumulative stall times and the running averages.
119 * For each runqueue, we track:
121 * tSOME[cpu] = time(nr_delayed_tasks[cpu] != 0)
122 * tFULL[cpu] = time(nr_delayed_tasks[cpu] && !nr_productive_tasks[cpu])
123 * tNONIDLE[cpu] = time(nr_nonidle_tasks[cpu] != 0)
125 * and then periodically aggregate:
127 * tNONIDLE = sum(tNONIDLE[i])
129 * tSOME = sum(tSOME[i] * tNONIDLE[i]) / tNONIDLE
130 * tFULL = sum(tFULL[i] * tNONIDLE[i]) / tNONIDLE
132 * %SOME = tSOME / period
133 * %FULL = tFULL / period
135 * This gives us an approximation of pressure that is practical
136 * cost-wise, yet way more sensitive and accurate than periodic
137 * sampling of the aggregate task states would be.
140 static int psi_bug __read_mostly;
142 DEFINE_STATIC_KEY_FALSE(psi_disabled);
143 static DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled);
145 #ifdef CONFIG_PSI_DEFAULT_DISABLED
146 static bool psi_enable;
148 static bool psi_enable = true;
150 static int __init setup_psi(char *str)
152 return kstrtobool(str, &psi_enable) == 0;
154 __setup("psi=", setup_psi);
156 /* Running averages - we need to be higher-res than loadavg */
157 #define PSI_FREQ (2*HZ+1) /* 2 sec intervals */
158 #define EXP_10s 1677 /* 1/exp(2s/10s) as fixed-point */
159 #define EXP_60s 1981 /* 1/exp(2s/60s) */
160 #define EXP_300s 2034 /* 1/exp(2s/300s) */
162 /* PSI trigger definitions */
163 #define WINDOW_MAX_US 10000000 /* Max window size is 10s */
164 #define UPDATES_PER_WINDOW 10 /* 10 updates per window */
166 /* Sampling frequency in nanoseconds */
167 static u64 psi_period __read_mostly;
169 /* System-level pressure and stall tracking */
170 static DEFINE_PER_CPU(struct psi_group_cpu, system_group_pcpu);
171 struct psi_group psi_system = {
172 .pcpu = &system_group_pcpu,
175 static void psi_avgs_work(struct work_struct *work);
177 static void poll_timer_fn(struct timer_list *t);
179 static void group_init(struct psi_group *group)
183 group->enabled = true;
184 for_each_possible_cpu(cpu)
185 seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
186 group->avg_last_update = sched_clock();
187 group->avg_next_update = group->avg_last_update + psi_period;
188 mutex_init(&group->avgs_lock);
190 /* Init avg trigger-related members */
191 INIT_LIST_HEAD(&group->avg_triggers);
192 memset(group->avg_nr_triggers, 0, sizeof(group->avg_nr_triggers));
193 INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
195 /* Init rtpoll trigger-related members */
196 atomic_set(&group->rtpoll_scheduled, 0);
197 mutex_init(&group->rtpoll_trigger_lock);
198 INIT_LIST_HEAD(&group->rtpoll_triggers);
199 group->rtpoll_min_period = U32_MAX;
200 group->rtpoll_next_update = ULLONG_MAX;
201 init_waitqueue_head(&group->rtpoll_wait);
202 timer_setup(&group->rtpoll_timer, poll_timer_fn, 0);
203 rcu_assign_pointer(group->rtpoll_task, NULL);
206 void __init psi_init(void)
209 static_branch_enable(&psi_disabled);
210 static_branch_disable(&psi_cgroups_enabled);
214 if (!cgroup_psi_enabled())
215 static_branch_disable(&psi_cgroups_enabled);
217 psi_period = jiffies_to_nsecs(PSI_FREQ);
218 group_init(&psi_system);
221 static bool test_state(unsigned int *tasks, enum psi_states state, bool oncpu)
225 return unlikely(tasks[NR_IOWAIT]);
227 return unlikely(tasks[NR_IOWAIT] && !tasks[NR_RUNNING]);
229 return unlikely(tasks[NR_MEMSTALL]);
231 return unlikely(tasks[NR_MEMSTALL] &&
232 tasks[NR_RUNNING] == tasks[NR_MEMSTALL_RUNNING]);
234 return unlikely(tasks[NR_RUNNING] > oncpu);
236 return unlikely(tasks[NR_RUNNING] && !oncpu);
238 return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
245 static void get_recent_times(struct psi_group *group, int cpu,
246 enum psi_aggregators aggregator, u32 *times,
247 u32 *pchanged_states)
249 struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
250 int current_cpu = raw_smp_processor_id();
251 unsigned int tasks[NR_PSI_TASK_COUNTS];
252 u64 now, state_start;
257 *pchanged_states = 0;
259 /* Snapshot a coherent view of the CPU state */
261 seq = read_seqcount_begin(&groupc->seq);
262 now = cpu_clock(cpu);
263 memcpy(times, groupc->times, sizeof(groupc->times));
264 state_mask = groupc->state_mask;
265 state_start = groupc->state_start;
266 if (cpu == current_cpu)
267 memcpy(tasks, groupc->tasks, sizeof(groupc->tasks));
268 } while (read_seqcount_retry(&groupc->seq, seq));
270 /* Calculate state time deltas against the previous snapshot */
271 for (s = 0; s < NR_PSI_STATES; s++) {
274 * In addition to already concluded states, we also
275 * incorporate currently active states on the CPU,
276 * since states may last for many sampling periods.
278 * This way we keep our delta sampling buckets small
279 * (u32) and our reported pressure close to what's
280 * actually happening.
282 if (state_mask & (1 << s))
283 times[s] += now - state_start;
285 delta = times[s] - groupc->times_prev[aggregator][s];
286 groupc->times_prev[aggregator][s] = times[s];
290 *pchanged_states |= (1 << s);
294 * When collect_percpu_times() from the avgs_work, we don't want to
295 * re-arm avgs_work when all CPUs are IDLE. But the current CPU running
296 * this avgs_work is never IDLE, cause avgs_work can't be shut off.
297 * So for the current CPU, we need to re-arm avgs_work only when
298 * (NR_RUNNING > 1 || NR_IOWAIT > 0 || NR_MEMSTALL > 0), for other CPUs
299 * we can just check PSI_NONIDLE delta.
301 if (current_work() == &group->avgs_work.work) {
304 if (cpu == current_cpu)
305 reschedule = tasks[NR_RUNNING] +
307 tasks[NR_MEMSTALL] > 1;
309 reschedule = *pchanged_states & (1 << PSI_NONIDLE);
312 *pchanged_states |= PSI_STATE_RESCHEDULE;
316 static void calc_avgs(unsigned long avg[3], int missed_periods,
317 u64 time, u64 period)
321 /* Fill in zeroes for periods of no activity */
322 if (missed_periods) {
323 avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods);
324 avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods);
325 avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods);
328 /* Sample the most recent active period */
329 pct = div_u64(time * 100, period);
331 avg[0] = calc_load(avg[0], EXP_10s, pct);
332 avg[1] = calc_load(avg[1], EXP_60s, pct);
333 avg[2] = calc_load(avg[2], EXP_300s, pct);
336 static void collect_percpu_times(struct psi_group *group,
337 enum psi_aggregators aggregator,
338 u32 *pchanged_states)
340 u64 deltas[NR_PSI_STATES - 1] = { 0, };
341 unsigned long nonidle_total = 0;
342 u32 changed_states = 0;
347 * Collect the per-cpu time buckets and average them into a
348 * single time sample that is normalized to wallclock time.
350 * For averaging, each CPU is weighted by its non-idle time in
351 * the sampling period. This eliminates artifacts from uneven
352 * loading, or even entirely idle CPUs.
354 for_each_possible_cpu(cpu) {
355 u32 times[NR_PSI_STATES];
357 u32 cpu_changed_states;
359 get_recent_times(group, cpu, aggregator, times,
360 &cpu_changed_states);
361 changed_states |= cpu_changed_states;
363 nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]);
364 nonidle_total += nonidle;
366 for (s = 0; s < PSI_NONIDLE; s++)
367 deltas[s] += (u64)times[s] * nonidle;
371 * Integrate the sample into the running statistics that are
372 * reported to userspace: the cumulative stall times and the
375 * Pressure percentages are sampled at PSI_FREQ. We might be
376 * called more often when the user polls more frequently than
377 * that; we might be called less often when there is no task
378 * activity, thus no data, and clock ticks are sporadic. The
379 * below handles both.
383 for (s = 0; s < NR_PSI_STATES - 1; s++)
384 group->total[aggregator][s] +=
385 div_u64(deltas[s], max(nonidle_total, 1UL));
388 *pchanged_states = changed_states;
391 /* Trigger tracking window manipulations */
392 static void window_reset(struct psi_window *win, u64 now, u64 value,
395 win->start_time = now;
396 win->start_value = value;
397 win->prev_growth = prev_growth;
401 * PSI growth tracking window update and growth calculation routine.
403 * This approximates a sliding tracking window by interpolating
404 * partially elapsed windows using historical growth data from the
405 * previous intervals. This minimizes memory requirements (by not storing
406 * all the intermediate values in the previous window) and simplifies
407 * the calculations. It works well because PSI signal changes only in
408 * positive direction and over relatively small window sizes the growth
409 * is close to linear.
411 static u64 window_update(struct psi_window *win, u64 now, u64 value)
416 elapsed = now - win->start_time;
417 growth = value - win->start_value;
419 * After each tracking window passes win->start_value and
420 * win->start_time get reset and win->prev_growth stores
421 * the average per-window growth of the previous window.
422 * win->prev_growth is then used to interpolate additional
423 * growth from the previous window assuming it was linear.
425 if (elapsed > win->size)
426 window_reset(win, now, value, growth);
430 remaining = win->size - elapsed;
431 growth += div64_u64(win->prev_growth * remaining, win->size);
437 static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
438 enum psi_aggregators aggregator)
440 struct psi_trigger *t;
441 u64 *total = group->total[aggregator];
442 struct list_head *triggers;
443 u64 *aggregator_total;
444 *update_total = false;
446 if (aggregator == PSI_AVGS) {
447 triggers = &group->avg_triggers;
448 aggregator_total = group->avg_total;
450 triggers = &group->rtpoll_triggers;
451 aggregator_total = group->rtpoll_total;
455 * On subsequent updates, calculate growth deltas and let
456 * watchers know when their specified thresholds are exceeded.
458 list_for_each_entry(t, triggers, node) {
462 new_stall = aggregator_total[t->state] != total[t->state];
464 /* Check for stall activity or a previous threshold breach */
465 if (!new_stall && !t->pending_event)
468 * Check for new stall activity, as well as deferred
469 * events that occurred in the last window after the
470 * trigger had already fired (we want to ratelimit
471 * events without dropping any).
475 * Multiple triggers might be looking at the same state,
476 * remember to update group->polling_total[] once we've
477 * been through all of them. Also remember to extend the
478 * polling time if we see new stall activity.
480 *update_total = true;
482 /* Calculate growth since last update */
483 growth = window_update(&t->win, now, total[t->state]);
484 if (!t->pending_event) {
485 if (growth < t->threshold)
488 t->pending_event = true;
491 /* Limit event signaling to once per window */
492 if (now < t->last_event_time + t->win.size)
495 /* Generate an event */
496 if (cmpxchg(&t->event, 0, 1) == 0) {
498 kernfs_notify(t->of->kn);
500 wake_up_interruptible(&t->event_wait);
502 t->last_event_time = now;
503 /* Reset threshold breach flag once event got generated */
504 t->pending_event = false;
507 return now + group->rtpoll_min_period;
510 static u64 update_averages(struct psi_group *group, u64 now)
512 unsigned long missed_periods = 0;
518 expires = group->avg_next_update;
519 if (now - expires >= psi_period)
520 missed_periods = div_u64(now - expires, psi_period);
523 * The periodic clock tick can get delayed for various
524 * reasons, especially on loaded systems. To avoid clock
525 * drift, we schedule the clock in fixed psi_period intervals.
526 * But the deltas we sample out of the per-cpu buckets above
527 * are based on the actual time elapsing between clock ticks.
529 avg_next_update = expires + ((1 + missed_periods) * psi_period);
530 period = now - (group->avg_last_update + (missed_periods * psi_period));
531 group->avg_last_update = now;
533 for (s = 0; s < NR_PSI_STATES - 1; s++) {
536 sample = group->total[PSI_AVGS][s] - group->avg_total[s];
538 * Due to the lockless sampling of the time buckets,
539 * recorded time deltas can slip into the next period,
540 * which under full pressure can result in samples in
541 * excess of the period length.
543 * We don't want to report non-sensical pressures in
544 * excess of 100%, nor do we want to drop such events
545 * on the floor. Instead we punt any overage into the
546 * future until pressure subsides. By doing this we
547 * don't underreport the occurring pressure curve, we
548 * just report it delayed by one period length.
550 * The error isn't cumulative. As soon as another
551 * delta slips from a period P to P+1, by definition
552 * it frees up its time T in P.
556 group->avg_total[s] += sample;
557 calc_avgs(group->avg[s], missed_periods, sample, period);
560 return avg_next_update;
563 static void psi_avgs_work(struct work_struct *work)
565 struct delayed_work *dwork;
566 struct psi_group *group;
571 dwork = to_delayed_work(work);
572 group = container_of(dwork, struct psi_group, avgs_work);
574 mutex_lock(&group->avgs_lock);
578 collect_percpu_times(group, PSI_AVGS, &changed_states);
580 * If there is task activity, periodically fold the per-cpu
581 * times and feed samples into the running averages. If things
582 * are idle and there is no data to process, stop the clock.
583 * Once restarted, we'll catch up the running averages in one
584 * go - see calc_avgs() and missed_periods.
586 if (now >= group->avg_next_update) {
587 update_triggers(group, now, &update_total, PSI_AVGS);
588 group->avg_next_update = update_averages(group, now);
591 if (changed_states & PSI_STATE_RESCHEDULE) {
592 schedule_delayed_work(dwork, nsecs_to_jiffies(
593 group->avg_next_update - now) + 1);
596 mutex_unlock(&group->avgs_lock);
599 static void init_rtpoll_triggers(struct psi_group *group, u64 now)
601 struct psi_trigger *t;
603 list_for_each_entry(t, &group->rtpoll_triggers, node)
604 window_reset(&t->win, now,
605 group->total[PSI_POLL][t->state], 0);
606 memcpy(group->rtpoll_total, group->total[PSI_POLL],
607 sizeof(group->rtpoll_total));
608 group->rtpoll_next_update = now + group->rtpoll_min_period;
611 /* Schedule polling if it's not already scheduled or forced. */
612 static void psi_schedule_rtpoll_work(struct psi_group *group, unsigned long delay,
615 struct task_struct *task;
618 * atomic_xchg should be called even when !force to provide a
619 * full memory barrier (see the comment inside psi_rtpoll_work).
621 if (atomic_xchg(&group->rtpoll_scheduled, 1) && !force)
626 task = rcu_dereference(group->rtpoll_task);
628 * kworker might be NULL in case psi_trigger_destroy races with
629 * psi_task_change (hotpath) which can't use locks
632 mod_timer(&group->rtpoll_timer, jiffies + delay);
634 atomic_set(&group->rtpoll_scheduled, 0);
639 static void psi_rtpoll_work(struct psi_group *group)
641 bool force_reschedule = false;
646 mutex_lock(&group->rtpoll_trigger_lock);
650 if (now > group->rtpoll_until) {
652 * We are either about to start or might stop polling if no
653 * state change was recorded. Resetting poll_scheduled leaves
654 * a small window for psi_group_change to sneak in and schedule
655 * an immediate poll_work before we get to rescheduling. One
656 * potential extra wakeup at the end of the polling window
657 * should be negligible and polling_next_update still keeps
658 * updates correctly on schedule.
660 atomic_set(&group->rtpoll_scheduled, 0);
662 * A task change can race with the poll worker that is supposed to
663 * report on it. To avoid missing events, ensure ordering between
664 * poll_scheduled and the task state accesses, such that if the poll
665 * worker misses the state update, the task change is guaranteed to
666 * reschedule the poll worker:
669 * atomic_set(poll_scheduled, 0)
675 * if atomic_xchg(poll_scheduled, 1) == 0:
676 * schedule poll worker
678 * The atomic_xchg() implies a full barrier.
682 /* Polling window is not over, keep rescheduling */
683 force_reschedule = true;
687 collect_percpu_times(group, PSI_POLL, &changed_states);
689 if (changed_states & group->rtpoll_states) {
690 /* Initialize trigger windows when entering polling mode */
691 if (now > group->rtpoll_until)
692 init_rtpoll_triggers(group, now);
695 * Keep the monitor active for at least the duration of the
696 * minimum tracking window as long as monitor states are
699 group->rtpoll_until = now +
700 group->rtpoll_min_period * UPDATES_PER_WINDOW;
703 if (now > group->rtpoll_until) {
704 group->rtpoll_next_update = ULLONG_MAX;
708 if (now >= group->rtpoll_next_update) {
709 group->rtpoll_next_update = update_triggers(group, now, &update_total, PSI_POLL);
711 memcpy(group->rtpoll_total, group->total[PSI_POLL],
712 sizeof(group->rtpoll_total));
715 psi_schedule_rtpoll_work(group,
716 nsecs_to_jiffies(group->rtpoll_next_update - now) + 1,
720 mutex_unlock(&group->rtpoll_trigger_lock);
723 static int psi_rtpoll_worker(void *data)
725 struct psi_group *group = (struct psi_group *)data;
727 sched_set_fifo_low(current);
730 wait_event_interruptible(group->rtpoll_wait,
731 atomic_cmpxchg(&group->rtpoll_wakeup, 1, 0) ||
732 kthread_should_stop());
733 if (kthread_should_stop())
736 psi_rtpoll_work(group);
741 static void poll_timer_fn(struct timer_list *t)
743 struct psi_group *group = from_timer(group, t, rtpoll_timer);
745 atomic_set(&group->rtpoll_wakeup, 1);
746 wake_up_interruptible(&group->rtpoll_wait);
749 static void record_times(struct psi_group_cpu *groupc, u64 now)
753 delta = now - groupc->state_start;
754 groupc->state_start = now;
756 if (groupc->state_mask & (1 << PSI_IO_SOME)) {
757 groupc->times[PSI_IO_SOME] += delta;
758 if (groupc->state_mask & (1 << PSI_IO_FULL))
759 groupc->times[PSI_IO_FULL] += delta;
762 if (groupc->state_mask & (1 << PSI_MEM_SOME)) {
763 groupc->times[PSI_MEM_SOME] += delta;
764 if (groupc->state_mask & (1 << PSI_MEM_FULL))
765 groupc->times[PSI_MEM_FULL] += delta;
768 if (groupc->state_mask & (1 << PSI_CPU_SOME)) {
769 groupc->times[PSI_CPU_SOME] += delta;
770 if (groupc->state_mask & (1 << PSI_CPU_FULL))
771 groupc->times[PSI_CPU_FULL] += delta;
774 if (groupc->state_mask & (1 << PSI_NONIDLE))
775 groupc->times[PSI_NONIDLE] += delta;
778 static void psi_group_change(struct psi_group *group, int cpu,
779 unsigned int clear, unsigned int set, u64 now,
782 struct psi_group_cpu *groupc;
787 groupc = per_cpu_ptr(group->pcpu, cpu);
790 * First we update the task counts according to the state
791 * change requested through the @clear and @set bits.
793 * Then if the cgroup PSI stats accounting enabled, we
794 * assess the aggregate resource states this CPU's tasks
795 * have been in since the last change, and account any
796 * SOME and FULL time these may have resulted in.
798 write_seqcount_begin(&groupc->seq);
801 * Start with TSK_ONCPU, which doesn't have a corresponding
802 * task count - it's just a boolean flag directly encoded in
803 * the state mask. Clear, set, or carry the current state if
804 * no changes are requested.
806 if (unlikely(clear & TSK_ONCPU)) {
809 } else if (unlikely(set & TSK_ONCPU)) {
810 state_mask = PSI_ONCPU;
813 state_mask = groupc->state_mask & PSI_ONCPU;
817 * The rest of the state mask is calculated based on the task
818 * counts. Update those first, then construct the mask.
820 for (t = 0, m = clear; m; m &= ~(1 << t), t++) {
823 if (groupc->tasks[t]) {
825 } else if (!psi_bug) {
826 printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u %u] clear=%x set=%x\n",
827 cpu, t, groupc->tasks[0],
828 groupc->tasks[1], groupc->tasks[2],
829 groupc->tasks[3], clear, set);
834 for (t = 0; set; set &= ~(1 << t), t++)
838 if (!group->enabled) {
840 * On the first group change after disabling PSI, conclude
841 * the current state and flush its time. This is unlikely
842 * to matter to the user, but aggregation (get_recent_times)
843 * may have already incorporated the live state into times_prev;
844 * avoid a delta sample underflow when PSI is later re-enabled.
846 if (unlikely(groupc->state_mask & (1 << PSI_NONIDLE)))
847 record_times(groupc, now);
849 groupc->state_mask = state_mask;
851 write_seqcount_end(&groupc->seq);
855 for (s = 0; s < NR_PSI_STATES; s++) {
856 if (test_state(groupc->tasks, s, state_mask & PSI_ONCPU))
857 state_mask |= (1 << s);
861 * Since we care about lost potential, a memstall is FULL
862 * when there are no other working tasks, but also when
863 * the CPU is actively reclaiming and nothing productive
864 * could run even if it were runnable. So when the current
865 * task in a cgroup is in_memstall, the corresponding groupc
866 * on that cpu is in PSI_MEM_FULL state.
868 if (unlikely((state_mask & PSI_ONCPU) && cpu_curr(cpu)->in_memstall))
869 state_mask |= (1 << PSI_MEM_FULL);
871 record_times(groupc, now);
873 groupc->state_mask = state_mask;
875 write_seqcount_end(&groupc->seq);
877 if (state_mask & group->rtpoll_states)
878 psi_schedule_rtpoll_work(group, 1, false);
880 if (wake_clock && !delayed_work_pending(&group->avgs_work))
881 schedule_delayed_work(&group->avgs_work, PSI_FREQ);
884 static inline struct psi_group *task_psi_group(struct task_struct *task)
886 #ifdef CONFIG_CGROUPS
887 if (static_branch_likely(&psi_cgroups_enabled))
888 return cgroup_psi(task_dfl_cgroup(task));
893 static void psi_flags_change(struct task_struct *task, int clear, int set)
895 if (((task->psi_flags & set) ||
896 (task->psi_flags & clear) != clear) &&
898 printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
899 task->pid, task->comm, task_cpu(task),
900 task->psi_flags, clear, set);
904 task->psi_flags &= ~clear;
905 task->psi_flags |= set;
908 void psi_task_change(struct task_struct *task, int clear, int set)
910 int cpu = task_cpu(task);
911 struct psi_group *group;
917 psi_flags_change(task, clear, set);
919 now = cpu_clock(cpu);
921 group = task_psi_group(task);
923 psi_group_change(group, cpu, clear, set, now, true);
924 } while ((group = group->parent));
927 void psi_task_switch(struct task_struct *prev, struct task_struct *next,
930 struct psi_group *group, *common = NULL;
931 int cpu = task_cpu(prev);
932 u64 now = cpu_clock(cpu);
935 psi_flags_change(next, 0, TSK_ONCPU);
937 * Set TSK_ONCPU on @next's cgroups. If @next shares any
938 * ancestors with @prev, those will already have @prev's
939 * TSK_ONCPU bit set, and we can stop the iteration there.
941 group = task_psi_group(next);
943 if (per_cpu_ptr(group->pcpu, cpu)->state_mask &
949 psi_group_change(group, cpu, 0, TSK_ONCPU, now, true);
950 } while ((group = group->parent));
954 int clear = TSK_ONCPU, set = 0;
955 bool wake_clock = true;
958 * When we're going to sleep, psi_dequeue() lets us
959 * handle TSK_RUNNING, TSK_MEMSTALL_RUNNING and
960 * TSK_IOWAIT here, where we can combine it with
961 * TSK_ONCPU and save walking common ancestors twice.
964 clear |= TSK_RUNNING;
965 if (prev->in_memstall)
966 clear |= TSK_MEMSTALL_RUNNING;
971 * Periodic aggregation shuts off if there is a period of no
972 * task changes, so we wake it back up if necessary. However,
973 * don't do this if the task change is the aggregation worker
974 * itself going to sleep, or we'll ping-pong forever.
976 if (unlikely((prev->flags & PF_WQ_WORKER) &&
977 wq_worker_last_func(prev) == psi_avgs_work))
981 psi_flags_change(prev, clear, set);
983 group = task_psi_group(prev);
987 psi_group_change(group, cpu, clear, set, now, wake_clock);
988 } while ((group = group->parent));
991 * TSK_ONCPU is handled up to the common ancestor. If there are
992 * any other differences between the two tasks (e.g. prev goes
993 * to sleep, or only one task is memstall), finish propagating
994 * those differences all the way up to the root.
996 if ((prev->psi_flags ^ next->psi_flags) & ~TSK_ONCPU) {
998 for (; group; group = group->parent)
999 psi_group_change(group, cpu, clear, set, now, wake_clock);
1004 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1005 void psi_account_irqtime(struct task_struct *task, u32 delta)
1007 int cpu = task_cpu(task);
1008 struct psi_group *group;
1009 struct psi_group_cpu *groupc;
1015 now = cpu_clock(cpu);
1017 group = task_psi_group(task);
1019 if (!group->enabled)
1022 groupc = per_cpu_ptr(group->pcpu, cpu);
1024 write_seqcount_begin(&groupc->seq);
1026 record_times(groupc, now);
1027 groupc->times[PSI_IRQ_FULL] += delta;
1029 write_seqcount_end(&groupc->seq);
1031 if (group->rtpoll_states & (1 << PSI_IRQ_FULL))
1032 psi_schedule_rtpoll_work(group, 1, false);
1033 } while ((group = group->parent));
1038 * psi_memstall_enter - mark the beginning of a memory stall section
1039 * @flags: flags to handle nested sections
1041 * Marks the calling task as being stalled due to a lack of memory,
1042 * such as waiting for a refault or performing reclaim.
1044 void psi_memstall_enter(unsigned long *flags)
1049 if (static_branch_likely(&psi_disabled))
1052 *flags = current->in_memstall;
1056 * in_memstall setting & accounting needs to be atomic wrt
1057 * changes to the task's scheduling state, otherwise we can
1058 * race with CPU migration.
1060 rq = this_rq_lock_irq(&rf);
1062 current->in_memstall = 1;
1063 psi_task_change(current, 0, TSK_MEMSTALL | TSK_MEMSTALL_RUNNING);
1065 rq_unlock_irq(rq, &rf);
1067 EXPORT_SYMBOL_GPL(psi_memstall_enter);
1070 * psi_memstall_leave - mark the end of an memory stall section
1071 * @flags: flags to handle nested memdelay sections
1073 * Marks the calling task as no longer stalled due to lack of memory.
1075 void psi_memstall_leave(unsigned long *flags)
1080 if (static_branch_likely(&psi_disabled))
1086 * in_memstall clearing & accounting needs to be atomic wrt
1087 * changes to the task's scheduling state, otherwise we could
1088 * race with CPU migration.
1090 rq = this_rq_lock_irq(&rf);
1092 current->in_memstall = 0;
1093 psi_task_change(current, TSK_MEMSTALL | TSK_MEMSTALL_RUNNING, 0);
1095 rq_unlock_irq(rq, &rf);
1097 EXPORT_SYMBOL_GPL(psi_memstall_leave);
1099 #ifdef CONFIG_CGROUPS
1100 int psi_cgroup_alloc(struct cgroup *cgroup)
1102 if (!static_branch_likely(&psi_cgroups_enabled))
1105 cgroup->psi = kzalloc(sizeof(struct psi_group), GFP_KERNEL);
1109 cgroup->psi->pcpu = alloc_percpu(struct psi_group_cpu);
1110 if (!cgroup->psi->pcpu) {
1114 group_init(cgroup->psi);
1115 cgroup->psi->parent = cgroup_psi(cgroup_parent(cgroup));
1119 void psi_cgroup_free(struct cgroup *cgroup)
1121 if (!static_branch_likely(&psi_cgroups_enabled))
1124 cancel_delayed_work_sync(&cgroup->psi->avgs_work);
1125 free_percpu(cgroup->psi->pcpu);
1126 /* All triggers must be removed by now */
1127 WARN_ONCE(cgroup->psi->rtpoll_states, "psi: trigger leak\n");
1132 * cgroup_move_task - move task to a different cgroup
1134 * @to: the target css_set
1136 * Move task to a new cgroup and safely migrate its associated stall
1137 * state between the different groups.
1139 * This function acquires the task's rq lock to lock out concurrent
1140 * changes to the task's scheduling state and - in case the task is
1141 * running - concurrent changes to its stall state.
1143 void cgroup_move_task(struct task_struct *task, struct css_set *to)
1145 unsigned int task_flags;
1149 if (!static_branch_likely(&psi_cgroups_enabled)) {
1151 * Lame to do this here, but the scheduler cannot be locked
1152 * from the outside, so we move cgroups from inside sched/.
1154 rcu_assign_pointer(task->cgroups, to);
1158 rq = task_rq_lock(task, &rf);
1161 * We may race with schedule() dropping the rq lock between
1162 * deactivating prev and switching to next. Because the psi
1163 * updates from the deactivation are deferred to the switch
1164 * callback to save cgroup tree updates, the task's scheduling
1165 * state here is not coherent with its psi state:
1167 * schedule() cgroup_move_task()
1171 * psi_dequeue() // defers TSK_RUNNING & TSK_IOWAIT updates
1175 * psi_task_change() // old cgroup
1176 * task->cgroups = to
1177 * psi_task_change() // new cgroup
1180 * psi_sched_switch() // does deferred updates in new cgroup
1182 * Don't rely on the scheduling state. Use psi_flags instead.
1184 task_flags = task->psi_flags;
1187 psi_task_change(task, task_flags, 0);
1189 /* See comment above */
1190 rcu_assign_pointer(task->cgroups, to);
1193 psi_task_change(task, 0, task_flags);
1195 task_rq_unlock(rq, task, &rf);
1198 void psi_cgroup_restart(struct psi_group *group)
1203 * After we disable psi_group->enabled, we don't actually
1204 * stop percpu tasks accounting in each psi_group_cpu,
1205 * instead only stop test_state() loop, record_times()
1206 * and averaging worker, see psi_group_change() for details.
1208 * When disable cgroup PSI, this function has nothing to sync
1209 * since cgroup pressure files are hidden and percpu psi_group_cpu
1210 * would see !psi_group->enabled and only do task accounting.
1212 * When re-enable cgroup PSI, this function use psi_group_change()
1213 * to get correct state mask from test_state() loop on tasks[],
1214 * and restart groupc->state_start from now, use .clear = .set = 0
1215 * here since no task status really changed.
1217 if (!group->enabled)
1220 for_each_possible_cpu(cpu) {
1221 struct rq *rq = cpu_rq(cpu);
1225 rq_lock_irq(rq, &rf);
1226 now = cpu_clock(cpu);
1227 psi_group_change(group, cpu, 0, 0, now, true);
1228 rq_unlock_irq(rq, &rf);
1231 #endif /* CONFIG_CGROUPS */
1233 int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
1235 bool only_full = false;
1239 if (static_branch_likely(&psi_disabled))
1242 /* Update averages before reporting them */
1243 mutex_lock(&group->avgs_lock);
1244 now = sched_clock();
1245 collect_percpu_times(group, PSI_AVGS, NULL);
1246 if (now >= group->avg_next_update)
1247 group->avg_next_update = update_averages(group, now);
1248 mutex_unlock(&group->avgs_lock);
1250 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1251 only_full = res == PSI_IRQ;
1254 for (full = 0; full < 2 - only_full; full++) {
1255 unsigned long avg[3] = { 0, };
1259 /* CPU FULL is undefined at the system level */
1260 if (!(group == &psi_system && res == PSI_CPU && full)) {
1261 for (w = 0; w < 3; w++)
1262 avg[w] = group->avg[res * 2 + full][w];
1263 total = div_u64(group->total[PSI_AVGS][res * 2 + full],
1267 seq_printf(m, "%s avg10=%lu.%02lu avg60=%lu.%02lu avg300=%lu.%02lu total=%llu\n",
1268 full || only_full ? "full" : "some",
1269 LOAD_INT(avg[0]), LOAD_FRAC(avg[0]),
1270 LOAD_INT(avg[1]), LOAD_FRAC(avg[1]),
1271 LOAD_INT(avg[2]), LOAD_FRAC(avg[2]),
1278 struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
1279 enum psi_res res, struct file *file,
1280 struct kernfs_open_file *of)
1282 struct psi_trigger *t;
1283 enum psi_states state;
1288 if (static_branch_likely(&psi_disabled))
1289 return ERR_PTR(-EOPNOTSUPP);
1292 * Checking the privilege here on file->f_cred implies that a privileged user
1293 * could open the file and delegate the write to an unprivileged one.
1295 privileged = cap_raised(file->f_cred->cap_effective, CAP_SYS_RESOURCE);
1297 if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2)
1298 state = PSI_IO_SOME + res * 2;
1299 else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2)
1300 state = PSI_IO_FULL + res * 2;
1302 return ERR_PTR(-EINVAL);
1304 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1305 if (res == PSI_IRQ && --state != PSI_IRQ_FULL)
1306 return ERR_PTR(-EINVAL);
1309 if (state >= PSI_NONIDLE)
1310 return ERR_PTR(-EINVAL);
1312 if (window_us == 0 || window_us > WINDOW_MAX_US)
1313 return ERR_PTR(-EINVAL);
1316 * Unprivileged users can only use 2s windows so that averages aggregation
1317 * work is used, and no RT threads need to be spawned.
1319 if (!privileged && window_us % 2000000)
1320 return ERR_PTR(-EINVAL);
1322 /* Check threshold */
1323 if (threshold_us == 0 || threshold_us > window_us)
1324 return ERR_PTR(-EINVAL);
1326 t = kmalloc(sizeof(*t), GFP_KERNEL);
1328 return ERR_PTR(-ENOMEM);
1332 t->threshold = threshold_us * NSEC_PER_USEC;
1333 t->win.size = window_us * NSEC_PER_USEC;
1334 window_reset(&t->win, sched_clock(),
1335 group->total[PSI_POLL][t->state], 0);
1338 t->last_event_time = 0;
1341 init_waitqueue_head(&t->event_wait);
1342 t->pending_event = false;
1343 t->aggregator = privileged ? PSI_POLL : PSI_AVGS;
1346 mutex_lock(&group->rtpoll_trigger_lock);
1348 if (!rcu_access_pointer(group->rtpoll_task)) {
1349 struct task_struct *task;
1351 task = kthread_create(psi_rtpoll_worker, group, "psimon");
1354 mutex_unlock(&group->rtpoll_trigger_lock);
1355 return ERR_CAST(task);
1357 atomic_set(&group->rtpoll_wakeup, 0);
1358 wake_up_process(task);
1359 rcu_assign_pointer(group->rtpoll_task, task);
1362 list_add(&t->node, &group->rtpoll_triggers);
1363 group->rtpoll_min_period = min(group->rtpoll_min_period,
1364 div_u64(t->win.size, UPDATES_PER_WINDOW));
1365 group->rtpoll_nr_triggers[t->state]++;
1366 group->rtpoll_states |= (1 << t->state);
1368 mutex_unlock(&group->rtpoll_trigger_lock);
1370 mutex_lock(&group->avgs_lock);
1372 list_add(&t->node, &group->avg_triggers);
1373 group->avg_nr_triggers[t->state]++;
1375 mutex_unlock(&group->avgs_lock);
1380 void psi_trigger_destroy(struct psi_trigger *t)
1382 struct psi_group *group;
1383 struct task_struct *task_to_destroy = NULL;
1386 * We do not check psi_disabled since it might have been disabled after
1387 * the trigger got created.
1394 * Wakeup waiters to stop polling and clear the queue to prevent it from
1395 * being accessed later. Can happen if cgroup is deleted from under a
1399 kernfs_notify(t->of->kn);
1401 wake_up_interruptible(&t->event_wait);
1403 if (t->aggregator == PSI_AVGS) {
1404 mutex_lock(&group->avgs_lock);
1405 if (!list_empty(&t->node)) {
1407 group->avg_nr_triggers[t->state]--;
1409 mutex_unlock(&group->avgs_lock);
1411 mutex_lock(&group->rtpoll_trigger_lock);
1412 if (!list_empty(&t->node)) {
1413 struct psi_trigger *tmp;
1414 u64 period = ULLONG_MAX;
1417 group->rtpoll_nr_triggers[t->state]--;
1418 if (!group->rtpoll_nr_triggers[t->state])
1419 group->rtpoll_states &= ~(1 << t->state);
1421 * Reset min update period for the remaining triggers
1422 * iff the destroying trigger had the min window size.
1424 if (group->rtpoll_min_period == div_u64(t->win.size, UPDATES_PER_WINDOW)) {
1425 list_for_each_entry(tmp, &group->rtpoll_triggers, node)
1426 period = min(period, div_u64(tmp->win.size,
1427 UPDATES_PER_WINDOW));
1428 group->rtpoll_min_period = period;
1430 /* Destroy rtpoll_task when the last trigger is destroyed */
1431 if (group->rtpoll_states == 0) {
1432 group->rtpoll_until = 0;
1433 task_to_destroy = rcu_dereference_protected(
1435 lockdep_is_held(&group->rtpoll_trigger_lock));
1436 rcu_assign_pointer(group->rtpoll_task, NULL);
1437 del_timer(&group->rtpoll_timer);
1440 mutex_unlock(&group->rtpoll_trigger_lock);
1444 * Wait for psi_schedule_rtpoll_work RCU to complete its read-side
1445 * critical section before destroying the trigger and optionally the
1450 * Stop kthread 'psimon' after releasing rtpoll_trigger_lock to prevent
1451 * a deadlock while waiting for psi_rtpoll_work to acquire
1452 * rtpoll_trigger_lock
1454 if (task_to_destroy) {
1456 * After the RCU grace period has expired, the worker
1457 * can no longer be found through group->rtpoll_task.
1459 kthread_stop(task_to_destroy);
1460 atomic_set(&group->rtpoll_scheduled, 0);
1465 __poll_t psi_trigger_poll(void **trigger_ptr,
1466 struct file *file, poll_table *wait)
1468 __poll_t ret = DEFAULT_POLLMASK;
1469 struct psi_trigger *t;
1471 if (static_branch_likely(&psi_disabled))
1472 return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
1474 t = smp_load_acquire(trigger_ptr);
1476 return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
1479 kernfs_generic_poll(t->of, wait);
1481 poll_wait(file, &t->event_wait, wait);
1483 if (cmpxchg(&t->event, 1, 0) == 1)
1489 #ifdef CONFIG_PROC_FS
1490 static int psi_io_show(struct seq_file *m, void *v)
1492 return psi_show(m, &psi_system, PSI_IO);
1495 static int psi_memory_show(struct seq_file *m, void *v)
1497 return psi_show(m, &psi_system, PSI_MEM);
1500 static int psi_cpu_show(struct seq_file *m, void *v)
1502 return psi_show(m, &psi_system, PSI_CPU);
1505 static int psi_io_open(struct inode *inode, struct file *file)
1507 return single_open(file, psi_io_show, NULL);
1510 static int psi_memory_open(struct inode *inode, struct file *file)
1512 return single_open(file, psi_memory_show, NULL);
1515 static int psi_cpu_open(struct inode *inode, struct file *file)
1517 return single_open(file, psi_cpu_show, NULL);
1520 static ssize_t psi_write(struct file *file, const char __user *user_buf,
1521 size_t nbytes, enum psi_res res)
1525 struct seq_file *seq;
1526 struct psi_trigger *new;
1528 if (static_branch_likely(&psi_disabled))
1534 buf_size = min(nbytes, sizeof(buf));
1535 if (copy_from_user(buf, user_buf, buf_size))
1538 buf[buf_size - 1] = '\0';
1540 seq = file->private_data;
1542 /* Take seq->lock to protect seq->private from concurrent writes */
1543 mutex_lock(&seq->lock);
1545 /* Allow only one trigger per file descriptor */
1547 mutex_unlock(&seq->lock);
1551 new = psi_trigger_create(&psi_system, buf, res, file, NULL);
1553 mutex_unlock(&seq->lock);
1554 return PTR_ERR(new);
1557 smp_store_release(&seq->private, new);
1558 mutex_unlock(&seq->lock);
1563 static ssize_t psi_io_write(struct file *file, const char __user *user_buf,
1564 size_t nbytes, loff_t *ppos)
1566 return psi_write(file, user_buf, nbytes, PSI_IO);
1569 static ssize_t psi_memory_write(struct file *file, const char __user *user_buf,
1570 size_t nbytes, loff_t *ppos)
1572 return psi_write(file, user_buf, nbytes, PSI_MEM);
1575 static ssize_t psi_cpu_write(struct file *file, const char __user *user_buf,
1576 size_t nbytes, loff_t *ppos)
1578 return psi_write(file, user_buf, nbytes, PSI_CPU);
1581 static __poll_t psi_fop_poll(struct file *file, poll_table *wait)
1583 struct seq_file *seq = file->private_data;
1585 return psi_trigger_poll(&seq->private, file, wait);
1588 static int psi_fop_release(struct inode *inode, struct file *file)
1590 struct seq_file *seq = file->private_data;
1592 psi_trigger_destroy(seq->private);
1593 return single_release(inode, file);
1596 static const struct proc_ops psi_io_proc_ops = {
1597 .proc_open = psi_io_open,
1598 .proc_read = seq_read,
1599 .proc_lseek = seq_lseek,
1600 .proc_write = psi_io_write,
1601 .proc_poll = psi_fop_poll,
1602 .proc_release = psi_fop_release,
1605 static const struct proc_ops psi_memory_proc_ops = {
1606 .proc_open = psi_memory_open,
1607 .proc_read = seq_read,
1608 .proc_lseek = seq_lseek,
1609 .proc_write = psi_memory_write,
1610 .proc_poll = psi_fop_poll,
1611 .proc_release = psi_fop_release,
1614 static const struct proc_ops psi_cpu_proc_ops = {
1615 .proc_open = psi_cpu_open,
1616 .proc_read = seq_read,
1617 .proc_lseek = seq_lseek,
1618 .proc_write = psi_cpu_write,
1619 .proc_poll = psi_fop_poll,
1620 .proc_release = psi_fop_release,
1623 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1624 static int psi_irq_show(struct seq_file *m, void *v)
1626 return psi_show(m, &psi_system, PSI_IRQ);
1629 static int psi_irq_open(struct inode *inode, struct file *file)
1631 return single_open(file, psi_irq_show, NULL);
1634 static ssize_t psi_irq_write(struct file *file, const char __user *user_buf,
1635 size_t nbytes, loff_t *ppos)
1637 return psi_write(file, user_buf, nbytes, PSI_IRQ);
1640 static const struct proc_ops psi_irq_proc_ops = {
1641 .proc_open = psi_irq_open,
1642 .proc_read = seq_read,
1643 .proc_lseek = seq_lseek,
1644 .proc_write = psi_irq_write,
1645 .proc_poll = psi_fop_poll,
1646 .proc_release = psi_fop_release,
1650 static int __init psi_proc_init(void)
1653 proc_mkdir("pressure", NULL);
1654 proc_create("pressure/io", 0666, NULL, &psi_io_proc_ops);
1655 proc_create("pressure/memory", 0666, NULL, &psi_memory_proc_ops);
1656 proc_create("pressure/cpu", 0666, NULL, &psi_cpu_proc_ops);
1657 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1658 proc_create("pressure/irq", 0666, NULL, &psi_irq_proc_ops);
1663 module_init(psi_proc_init);
1665 #endif /* CONFIG_PROC_FS */