1/*
2 * Pressure stall information for CPU, memory and IO
3 *
4 * Copyright (c) 2018 Facebook, Inc.
5 * Author: Johannes Weiner <hannes@cmpxchg.org>
6 *
7 * When CPU, memory and IO are contended, tasks experience delays that
8 * reduce throughput and introduce latencies into the workload. Memory
9 * and IO contention, in addition, can cause a full loss of forward
10 * progress in which the CPU goes idle.
11 *
12 * This code aggregates individual task delays into resource pressure
13 * metrics that indicate problems with both workload health and
14 * resource utilization.
15 *
16 * Model
17 *
18 * The time in which a task can execute on a CPU is our baseline for
19 * productivity. Pressure expresses the amount of time in which this
20 * potential cannot be realized due to resource contention.
21 *
22 * This concept of productivity has two components: the workload and
23 * the CPU. To measure the impact of pressure on both, we define two
24 * contention states for a resource: SOME and FULL.
25 *
26 * In the SOME state of a given resource, one or more tasks are
27 * delayed on that resource. This affects the workload's ability to
28 * perform work, but the CPU may still be executing other tasks.
29 *
30 * In the FULL state of a given resource, all non-idle tasks are
31 * delayed on that resource such that nobody is advancing and the CPU
32 * goes idle. This leaves both workload and CPU unproductive.
33 *
34 * (Naturally, the FULL state doesn't exist for the CPU resource.)
35 *
36 * SOME = nr_delayed_tasks != 0
37 * FULL = nr_delayed_tasks != 0 && nr_running_tasks == 0
38 *
39 * The percentage of wallclock time spent in those compound stall
40 * states gives pressure numbers between 0 and 100 for each resource,
41 * where the SOME percentage indicates workload slowdowns and the FULL
42 * percentage indicates reduced CPU utilization:
43 *
44 * %SOME = time(SOME) / period
45 * %FULL = time(FULL) / period
46 *
47 * Multiple CPUs
48 *
49 * The more tasks and available CPUs there are, the more work can be
50 * performed concurrently. This means that the potential that can go
51 * unrealized due to resource contention *also* scales with non-idle
52 * tasks and CPUs.
53 *
54 * Consider a scenario where 257 number crunching tasks are trying to
55 * run concurrently on 256 CPUs. If we simply aggregated the task
56 * states, we would have to conclude a CPU SOME pressure number of
57 * 100%, since *somebody* is waiting on a runqueue at all
58 * times. However, that is clearly not the amount of contention the
59 * workload is experiencing: only one out of 256 possible exceution
60 * threads will be contended at any given time, or about 0.4%.
61 *
62 * Conversely, consider a scenario of 4 tasks and 4 CPUs where at any
63 * given time *one* of the tasks is delayed due to a lack of memory.
64 * Again, looking purely at the task state would yield a memory FULL
65 * pressure number of 0%, since *somebody* is always making forward
66 * progress. But again this wouldn't capture the amount of execution
67 * potential lost, which is 1 out of 4 CPUs, or 25%.
68 *
69 * To calculate wasted potential (pressure) with multiple processors,
70 * we have to base our calculation on the number of non-idle tasks in
71 * conjunction with the number of available CPUs, which is the number
72 * of potential execution threads. SOME becomes then the proportion of
73 * delayed tasks to possibe threads, and FULL is the share of possible
74 * threads that are unproductive due to delays:
75 *
76 * threads = min(nr_nonidle_tasks, nr_cpus)
77 * SOME = min(nr_delayed_tasks / threads, 1)
78 * FULL = (threads - min(nr_running_tasks, threads)) / threads
79 *
80 * For the 257 number crunchers on 256 CPUs, this yields:
81 *
82 * threads = min(257, 256)
83 * SOME = min(1 / 256, 1) = 0.4%
84 * FULL = (256 - min(257, 256)) / 256 = 0%
85 *
86 * For the 1 out of 4 memory-delayed tasks, this yields:
87 *
88 * threads = min(4, 4)
89 * SOME = min(1 / 4, 1) = 25%
90 * FULL = (4 - min(3, 4)) / 4 = 25%
91 *
92 * [ Substitute nr_cpus with 1, and you can see that it's a natural
93 * extension of the single-CPU model. ]
94 *
95 * Implementation
96 *
97 * To assess the precise time spent in each such state, we would have
98 * to freeze the system on task changes and start/stop the state
99 * clocks accordingly. Obviously that doesn't scale in practice.
100 *
101 * Because the scheduler aims to distribute the compute load evenly
102 * among the available CPUs, we can track task state locally to each
103 * CPU and, at much lower frequency, extrapolate the global state for
104 * the cumulative stall times and the running averages.
105 *
106 * For each runqueue, we track:
107 *
108 * tSOME[cpu] = time(nr_delayed_tasks[cpu] != 0)
109 * tFULL[cpu] = time(nr_delayed_tasks[cpu] && !nr_running_tasks[cpu])
110 * tNONIDLE[cpu] = time(nr_nonidle_tasks[cpu] != 0)
111 *
112 * and then periodically aggregate:
113 *
114 * tNONIDLE = sum(tNONIDLE[i])
115 *
116 * tSOME = sum(tSOME[i] * tNONIDLE[i]) / tNONIDLE
117 * tFULL = sum(tFULL[i] * tNONIDLE[i]) / tNONIDLE
118 *
119 * %SOME = tSOME / period
120 * %FULL = tFULL / period
121 *
122 * This gives us an approximation of pressure that is practical
123 * cost-wise, yet way more sensitive and accurate than periodic
124 * sampling of the aggregate task states would be.
125 */
126
127#include "../workqueue_internal.h"
128#include <linux/sched/loadavg.h>
129#include <linux/seq_file.h>
130#include <linux/proc_fs.h>
131#include <linux/seqlock.h>
132#include <linux/cgroup.h>
133#include <linux/module.h>
134#include <linux/sched.h>
135#include <linux/psi.h>
136#include "sched.h"
137
138static int psi_bug __read_mostly;
139
140DEFINE_STATIC_KEY_FALSE(psi_disabled);
141
142#ifdef CONFIG_PSI_DEFAULT_DISABLED
143bool psi_enable;
144#else
145bool psi_enable = true;
146#endif
147static int __init setup_psi(char *str)
148{
149 return kstrtobool(str, &psi_enable) == 0;
150}
151__setup("psi=", setup_psi);
152
153/* Running averages - we need to be higher-res than loadavg */
154#define PSI_FREQ (2*HZ+1) /* 2 sec intervals */
155#define EXP_10s 1677 /* 1/exp(2s/10s) as fixed-point */
156#define EXP_60s 1981 /* 1/exp(2s/60s) */
157#define EXP_300s 2034 /* 1/exp(2s/300s) */
158
159/* Sampling frequency in nanoseconds */
160static u64 psi_period __read_mostly;
161
162/* System-level pressure and stall tracking */
163static DEFINE_PER_CPU(struct psi_group_cpu, system_group_pcpu);
164static struct psi_group psi_system = {
165 .pcpu = &system_group_pcpu,
166};
167
168static void psi_update_work(struct work_struct *work);
169
170static void group_init(struct psi_group *group)
171{
172 int cpu;
173
174 for_each_possible_cpu(cpu)
175 seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
176 group->next_update = sched_clock() + psi_period;
177 INIT_DELAYED_WORK(&group->clock_work, psi_update_work);
178 mutex_init(&group->stat_lock);
179}
180
181void __init psi_init(void)
182{
183 if (!psi_enable) {
184 static_branch_enable(&psi_disabled);
185 return;
186 }
187
188 psi_period = jiffies_to_nsecs(PSI_FREQ);
189 group_init(&psi_system);
190}
191
192static bool test_state(unsigned int *tasks, enum psi_states state)
193{
194 switch (state) {
195 case PSI_IO_SOME:
196 return tasks[NR_IOWAIT];
197 case PSI_IO_FULL:
198 return tasks[NR_IOWAIT] && !tasks[NR_RUNNING];
199 case PSI_MEM_SOME:
200 return tasks[NR_MEMSTALL];
201 case PSI_MEM_FULL:
202 return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
203 case PSI_CPU_SOME:
204 return tasks[NR_RUNNING] > 1;
205 case PSI_NONIDLE:
206 return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
207 tasks[NR_RUNNING];
208 default:
209 return false;
210 }
211}
212
213static void get_recent_times(struct psi_group *group, int cpu, u32 *times)
214{
215 struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
216 unsigned int tasks[NR_PSI_TASK_COUNTS];
217 u64 now, state_start;
218 unsigned int seq;
219 int s;
220
221 /* Snapshot a coherent view of the CPU state */
222 do {
223 seq = read_seqcount_begin(&groupc->seq);
224 now = cpu_clock(cpu);
225 memcpy(times, groupc->times, sizeof(groupc->times));
226 memcpy(tasks, groupc->tasks, sizeof(groupc->tasks));
227 state_start = groupc->state_start;
228 } while (read_seqcount_retry(&groupc->seq, seq));
229
230 /* Calculate state time deltas against the previous snapshot */
231 for (s = 0; s < NR_PSI_STATES; s++) {
232 u32 delta;
233 /*
234 * In addition to already concluded states, we also
235 * incorporate currently active states on the CPU,
236 * since states may last for many sampling periods.
237 *
238 * This way we keep our delta sampling buckets small
239 * (u32) and our reported pressure close to what's
240 * actually happening.
241 */
242 if (test_state(tasks, s))
243 times[s] += now - state_start;
244
245 delta = times[s] - groupc->times_prev[s];
246 groupc->times_prev[s] = times[s];
247
248 times[s] = delta;
249 }
250}
251
252static void calc_avgs(unsigned long avg[3], int missed_periods,
253 u64 time, u64 period)
254{
255 unsigned long pct;
256
257 /* Fill in zeroes for periods of no activity */
258 if (missed_periods) {
259 avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods);
260 avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods);
261 avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods);
262 }
263
264 /* Sample the most recent active period */
265 pct = div_u64(time * 100, period);
266 pct *= FIXED_1;
267 avg[0] = calc_load(avg[0], EXP_10s, pct);
268 avg[1] = calc_load(avg[1], EXP_60s, pct);
269 avg[2] = calc_load(avg[2], EXP_300s, pct);
270}
271
272static bool update_stats(struct psi_group *group)
273{
274 u64 deltas[NR_PSI_STATES - 1] = { 0, };
275 unsigned long missed_periods = 0;
276 unsigned long nonidle_total = 0;
277 u64 now, expires, period;
278 int cpu;
279 int s;
280
281 mutex_lock(&group->stat_lock);
282
283 /*
284 * Collect the per-cpu time buckets and average them into a
285 * single time sample that is normalized to wallclock time.
286 *
287 * For averaging, each CPU is weighted by its non-idle time in
288 * the sampling period. This eliminates artifacts from uneven
289 * loading, or even entirely idle CPUs.
290 */
291 for_each_possible_cpu(cpu) {
292 u32 times[NR_PSI_STATES];
293 u32 nonidle;
294
295 get_recent_times(group, cpu, times);
296
297 nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]);
298 nonidle_total += nonidle;
299
300 for (s = 0; s < PSI_NONIDLE; s++)
301 deltas[s] += (u64)times[s] * nonidle;
302 }
303
304 /*
305 * Integrate the sample into the running statistics that are
306 * reported to userspace: the cumulative stall times and the
307 * decaying averages.
308 *
309 * Pressure percentages are sampled at PSI_FREQ. We might be
310 * called more often when the user polls more frequently than
311 * that; we might be called less often when there is no task
312 * activity, thus no data, and clock ticks are sporadic. The
313 * below handles both.
314 */
315
316 /* total= */
317 for (s = 0; s < NR_PSI_STATES - 1; s++)
318 group->total[s] += div_u64(deltas[s], max(nonidle_total, 1UL));
319
320 /* avgX= */
321 now = sched_clock();
322 expires = group->next_update;
323 if (now < expires)
324 goto out;
325 if (now - expires >= psi_period)
326 missed_periods = div_u64(now - expires, psi_period);
327
328 /*
329 * The periodic clock tick can get delayed for various
330 * reasons, especially on loaded systems. To avoid clock
331 * drift, we schedule the clock in fixed psi_period intervals.
332 * But the deltas we sample out of the per-cpu buckets above
333 * are based on the actual time elapsing between clock ticks.
334 */
335 group->next_update = expires + ((1 + missed_periods) * psi_period);
336 period = now - (group->last_update + (missed_periods * psi_period));
337 group->last_update = now;
338
339 for (s = 0; s < NR_PSI_STATES - 1; s++) {
340 u32 sample;
341
342 sample = group->total[s] - group->total_prev[s];
343 /*
344 * Due to the lockless sampling of the time buckets,
345 * recorded time deltas can slip into the next period,
346 * which under full pressure can result in samples in
347 * excess of the period length.
348 *
349 * We don't want to report non-sensical pressures in
350 * excess of 100%, nor do we want to drop such events
351 * on the floor. Instead we punt any overage into the
352 * future until pressure subsides. By doing this we
353 * don't underreport the occurring pressure curve, we
354 * just report it delayed by one period length.
355 *
356 * The error isn't cumulative. As soon as another
357 * delta slips from a period P to P+1, by definition
358 * it frees up its time T in P.
359 */
360 if (sample > period)
361 sample = period;
362 group->total_prev[s] += sample;
363 calc_avgs(group->avg[s], missed_periods, sample, period);
364 }
365out:
366 mutex_unlock(&group->stat_lock);
367 return nonidle_total;
368}
369
370static void psi_update_work(struct work_struct *work)
371{
372 struct delayed_work *dwork;
373 struct psi_group *group;
374 bool nonidle;
375
376 dwork = to_delayed_work(work);
377 group = container_of(dwork, struct psi_group, clock_work);
378
379 /*
380 * If there is task activity, periodically fold the per-cpu
381 * times and feed samples into the running averages. If things
382 * are idle and there is no data to process, stop the clock.
383 * Once restarted, we'll catch up the running averages in one
384 * go - see calc_avgs() and missed_periods.
385 */
386
387 nonidle = update_stats(group);
388
389 if (nonidle) {
390 unsigned long delay = 0;
391 u64 now;
392
393 now = sched_clock();
394 if (group->next_update > now)
395 delay = nsecs_to_jiffies(group->next_update - now) + 1;
396 schedule_delayed_work(dwork, delay);
397 }
398}
399
400static void record_times(struct psi_group_cpu *groupc, int cpu,
401 bool memstall_tick)
402{
403 u32 delta;
404 u64 now;
405
406 now = cpu_clock(cpu);
407 delta = now - groupc->state_start;
408 groupc->state_start = now;
409
410 if (test_state(groupc->tasks, PSI_IO_SOME)) {
411 groupc->times[PSI_IO_SOME] += delta;
412 if (test_state(groupc->tasks, PSI_IO_FULL))
413 groupc->times[PSI_IO_FULL] += delta;
414 }
415
416 if (test_state(groupc->tasks, PSI_MEM_SOME)) {
417 groupc->times[PSI_MEM_SOME] += delta;
418 if (test_state(groupc->tasks, PSI_MEM_FULL))
419 groupc->times[PSI_MEM_FULL] += delta;
420 else if (memstall_tick) {
421 u32 sample;
422 /*
423 * Since we care about lost potential, a
424 * memstall is FULL when there are no other
425 * working tasks, but also when the CPU is
426 * actively reclaiming and nothing productive
427 * could run even if it were runnable.
428 *
429 * When the timer tick sees a reclaiming CPU,
430 * regardless of runnable tasks, sample a FULL
431 * tick (or less if it hasn't been a full tick
432 * since the last state change).
433 */
434 sample = min(delta, (u32)jiffies_to_nsecs(1));
435 groupc->times[PSI_MEM_FULL] += sample;
436 }
437 }
438
439 if (test_state(groupc->tasks, PSI_CPU_SOME))
440 groupc->times[PSI_CPU_SOME] += delta;
441
442 if (test_state(groupc->tasks, PSI_NONIDLE))
443 groupc->times[PSI_NONIDLE] += delta;
444}
445
446static void psi_group_change(struct psi_group *group, int cpu,
447 unsigned int clear, unsigned int set)
448{
449 struct psi_group_cpu *groupc;
450 unsigned int t, m;
451
452 groupc = per_cpu_ptr(group->pcpu, cpu);
453
454 /*
455 * First we assess the aggregate resource states this CPU's
456 * tasks have been in since the last change, and account any
457 * SOME and FULL time these may have resulted in.
458 *
459 * Then we update the task counts according to the state
460 * change requested through the @clear and @set bits.
461 */
462 write_seqcount_begin(&groupc->seq);
463
464 record_times(groupc, cpu, false);
465
466 for (t = 0, m = clear; m; m &= ~(1 << t), t++) {
467 if (!(m & (1 << t)))
468 continue;
469 if (groupc->tasks[t] == 0 && !psi_bug) {
470 printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u] clear=%x set=%x\n",
471 cpu, t, groupc->tasks[0],
472 groupc->tasks[1], groupc->tasks[2],
473 clear, set);
474 psi_bug = 1;
475 }
476 groupc->tasks[t]--;
477 }
478
479 for (t = 0; set; set &= ~(1 << t), t++)
480 if (set & (1 << t))
481 groupc->tasks[t]++;
482
483 write_seqcount_end(&groupc->seq);
484}
485
486static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
487{
488#ifdef CONFIG_CGROUPS
489 struct cgroup *cgroup = NULL;
490
491 if (!*iter)
492 cgroup = task->cgroups->dfl_cgrp;
493 else if (*iter == &psi_system)
494 return NULL;
495 else
496 cgroup = cgroup_parent(*iter);
497
498 if (cgroup && cgroup_parent(cgroup)) {
499 *iter = cgroup;
500 return cgroup_psi(cgroup);
501 }
502#else
503 if (*iter)
504 return NULL;
505#endif
506 *iter = &psi_system;
507 return &psi_system;
508}
509
510void psi_task_change(struct task_struct *task, int clear, int set)
511{
512 int cpu = task_cpu(task);
513 struct psi_group *group;
514 bool wake_clock = true;
515 void *iter = NULL;
516
517 if (!task->pid)
518 return;
519
520 if (((task->psi_flags & set) ||
521 (task->psi_flags & clear) != clear) &&
522 !psi_bug) {
523 printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
524 task->pid, task->comm, cpu,
525 task->psi_flags, clear, set);
526 psi_bug = 1;
527 }
528
529 task->psi_flags &= ~clear;
530 task->psi_flags |= set;
531
532 /*
533 * Periodic aggregation shuts off if there is a period of no
534 * task changes, so we wake it back up if necessary. However,
535 * don't do this if the task change is the aggregation worker
536 * itself going to sleep, or we'll ping-pong forever.
537 */
538 if (unlikely((clear & TSK_RUNNING) &&
539 (task->flags & PF_WQ_WORKER) &&
540 wq_worker_last_func(task) == psi_update_work))
541 wake_clock = false;
542
543 while ((group = iterate_groups(task, &iter))) {
544 psi_group_change(group, cpu, clear, set);
545 if (wake_clock && !delayed_work_pending(&group->clock_work))
546 schedule_delayed_work(&group->clock_work, PSI_FREQ);
547 }
548}
549
550void psi_memstall_tick(struct task_struct *task, int cpu)
551{
552 struct psi_group *group;
553 void *iter = NULL;
554
555 while ((group = iterate_groups(task, &iter))) {
556 struct psi_group_cpu *groupc;
557
558 groupc = per_cpu_ptr(group->pcpu, cpu);
559 write_seqcount_begin(&groupc->seq);
560 record_times(groupc, cpu, true);
561 write_seqcount_end(&groupc->seq);
562 }
563}
564
565/**
566 * psi_memstall_enter - mark the beginning of a memory stall section
567 * @flags: flags to handle nested sections
568 *
569 * Marks the calling task as being stalled due to a lack of memory,
570 * such as waiting for a refault or performing reclaim.
571 */
572void psi_memstall_enter(unsigned long *flags)
573{
574 struct rq_flags rf;
575 struct rq *rq;
576
577 if (static_branch_likely(&psi_disabled))
578 return;
579
580 *flags = current->flags & PF_MEMSTALL;
581 if (*flags)
582 return;
583 /*
584 * PF_MEMSTALL setting & accounting needs to be atomic wrt
585 * changes to the task's scheduling state, otherwise we can
586 * race with CPU migration.
587 */
588 rq = this_rq_lock_irq(&rf);
589
590 current->flags |= PF_MEMSTALL;
591 psi_task_change(current, 0, TSK_MEMSTALL);
592
593 rq_unlock_irq(rq, &rf);
594}
595
596/**
597 * psi_memstall_leave - mark the end of an memory stall section
598 * @flags: flags to handle nested memdelay sections
599 *
600 * Marks the calling task as no longer stalled due to lack of memory.
601 */
602void psi_memstall_leave(unsigned long *flags)
603{
604 struct rq_flags rf;
605 struct rq *rq;
606
607 if (static_branch_likely(&psi_disabled))
608 return;
609
610 if (*flags)
611 return;
612 /*
613 * PF_MEMSTALL clearing & accounting needs to be atomic wrt
614 * changes to the task's scheduling state, otherwise we could
615 * race with CPU migration.
616 */
617 rq = this_rq_lock_irq(&rf);
618
619 current->flags &= ~PF_MEMSTALL;
620 psi_task_change(current, TSK_MEMSTALL, 0);
621
622 rq_unlock_irq(rq, &rf);
623}
624
625#ifdef CONFIG_CGROUPS
626int psi_cgroup_alloc(struct cgroup *cgroup)
627{
628 if (static_branch_likely(&psi_disabled))
629 return 0;
630
631 cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
632 if (!cgroup->psi.pcpu)
633 return -ENOMEM;
634 group_init(&cgroup->psi);
635 return 0;
636}
637
638void psi_cgroup_free(struct cgroup *cgroup)
639{
640 if (static_branch_likely(&psi_disabled))
641 return;
642
643 cancel_delayed_work_sync(&cgroup->psi.clock_work);
644 free_percpu(cgroup->psi.pcpu);
645}
646
647/**
648 * cgroup_move_task - move task to a different cgroup
649 * @task: the task
650 * @to: the target css_set
651 *
652 * Move task to a new cgroup and safely migrate its associated stall
653 * state between the different groups.
654 *
655 * This function acquires the task's rq lock to lock out concurrent
656 * changes to the task's scheduling state and - in case the task is
657 * running - concurrent changes to its stall state.
658 */
659void cgroup_move_task(struct task_struct *task, struct css_set *to)
660{
661 unsigned int task_flags = 0;
662 struct rq_flags rf;
663 struct rq *rq;
664
665 if (static_branch_likely(&psi_disabled)) {
666 /*
667 * Lame to do this here, but the scheduler cannot be locked
668 * from the outside, so we move cgroups from inside sched/.
669 */
670 rcu_assign_pointer(task->cgroups, to);
671 return;
672 }
673
674 rq = task_rq_lock(task, &rf);
675
676 if (task_on_rq_queued(task))
677 task_flags = TSK_RUNNING;
678 else if (task->in_iowait)
679 task_flags = TSK_IOWAIT;
680
681 if (task->flags & PF_MEMSTALL)
682 task_flags |= TSK_MEMSTALL;
683
684 if (task_flags)
685 psi_task_change(task, task_flags, 0);
686
687 /* See comment above */
688 rcu_assign_pointer(task->cgroups, to);
689
690 if (task_flags)
691 psi_task_change(task, 0, task_flags);
692
693 task_rq_unlock(rq, task, &rf);
694}
695#endif /* CONFIG_CGROUPS */
696
697int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
698{
699 int full;
700
701 if (static_branch_likely(&psi_disabled))
702 return -EOPNOTSUPP;
703
704 update_stats(group);
705
706 for (full = 0; full < 2 - (res == PSI_CPU); full++) {
707 unsigned long avg[3];
708 u64 total;
709 int w;
710
711 for (w = 0; w < 3; w++)
712 avg[w] = group->avg[res * 2 + full][w];
713 total = div_u64(group->total[res * 2 + full], NSEC_PER_USEC);
714
715 seq_printf(m, "%s avg10=%lu.%02lu avg60=%lu.%02lu avg300=%lu.%02lu total=%llu\n",
716 full ? "full" : "some",
717 LOAD_INT(avg[0]), LOAD_FRAC(avg[0]),
718 LOAD_INT(avg[1]), LOAD_FRAC(avg[1]),
719 LOAD_INT(avg[2]), LOAD_FRAC(avg[2]),
720 total);
721 }
722
723 return 0;
724}
725
726static int psi_io_show(struct seq_file *m, void *v)
727{
728 return psi_show(m, &psi_system, PSI_IO);
729}
730
731static int psi_memory_show(struct seq_file *m, void *v)
732{
733 return psi_show(m, &psi_system, PSI_MEM);
734}
735
736static int psi_cpu_show(struct seq_file *m, void *v)
737{
738 return psi_show(m, &psi_system, PSI_CPU);
739}
740
741static int psi_io_open(struct inode *inode, struct file *file)
742{
743 return single_open(file, psi_io_show, NULL);
744}
745
746static int psi_memory_open(struct inode *inode, struct file *file)
747{
748 return single_open(file, psi_memory_show, NULL);
749}
750
751static int psi_cpu_open(struct inode *inode, struct file *file)
752{
753 return single_open(file, psi_cpu_show, NULL);
754}
755
756static const struct file_operations psi_io_fops = {
757 .open = psi_io_open,
758 .read = seq_read,
759 .llseek = seq_lseek,
760 .release = single_release,
761};
762
763static const struct file_operations psi_memory_fops = {
764 .open = psi_memory_open,
765 .read = seq_read,
766 .llseek = seq_lseek,
767 .release = single_release,
768};
769
770static const struct file_operations psi_cpu_fops = {
771 .open = psi_cpu_open,
772 .read = seq_read,
773 .llseek = seq_lseek,
774 .release = single_release,
775};
776
777static int __init psi_proc_init(void)
778{
779 proc_mkdir("pressure", NULL);
780 proc_create("pressure/io", 0, NULL, &psi_io_fops);
781 proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
782 proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
783 return 0;
784}
785module_init(psi_proc_init);
786