kernel/sched/psi.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
setup_psi
group_init
psi_init
test_state
get_recent_times
calc_avgs
collect_percpu_times
update_averages
psi_avgs_work
window_reset
window_update
init_triggers
update_triggers
psi_schedule_poll_work
psi_poll_work
record_times
psi_group_change
iterate_groups
psi_task_change
psi_memstall_tick
psi_memstall_enter
psi_memstall_leave
psi_cgroup_alloc
psi_cgroup_free
cgroup_move_task
psi_show
psi_io_show
psi_memory_show
psi_cpu_show
psi_io_open
psi_memory_open
psi_cpu_open
psi_trigger_create
psi_trigger_destroy
psi_trigger_replace
psi_trigger_poll
psi_write
psi_io_write
psi_memory_write
psi_cpu_write
psi_fop_poll
psi_fop_release
psi_proc_init
   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  * Polling support by Suren Baghdasaryan <surenb@google.com>
   8  * Copyright (c) 2018 Google, Inc.
   9  *
  10  * When CPU, memory and IO are contended, tasks experience delays that
  11  * reduce throughput and introduce latencies into the workload. Memory
  12  * and IO contention, in addition, can cause a full loss of forward
  13  * progress in which the CPU goes idle.
  14  *
  15  * This code aggregates individual task delays into resource pressure
  16  * metrics that indicate problems with both workload health and
  17  * resource utilization.
  18  *
  19  *                      Model
  20  *
  21  * The time in which a task can execute on a CPU is our baseline for
  22  * productivity. Pressure expresses the amount of time in which this
  23  * potential cannot be realized due to resource contention.
  24  *
  25  * This concept of productivity has two components: the workload and
  26  * the CPU. To measure the impact of pressure on both, we define two
  27  * contention states for a resource: SOME and FULL.
  28  *
  29  * In the SOME state of a given resource, one or more tasks are
  30  * delayed on that resource. This affects the workload's ability to
  31  * perform work, but the CPU may still be executing other tasks.
  32  *
  33  * In the FULL state of a given resource, all non-idle tasks are
  34  * delayed on that resource such that nobody is advancing and the CPU
  35  * goes idle. This leaves both workload and CPU unproductive.
  36  *
  37  * (Naturally, the FULL state doesn't exist for the CPU resource.)
  38  *
  39  *      SOME = nr_delayed_tasks != 0
  40  *      FULL = nr_delayed_tasks != 0 && nr_running_tasks == 0
  41  *
  42  * The percentage of wallclock time spent in those compound stall
  43  * states gives pressure numbers between 0 and 100 for each resource,
  44  * where the SOME percentage indicates workload slowdowns and the FULL
  45  * percentage indicates reduced CPU utilization:
  46  *
  47  *      %SOME = time(SOME) / period
  48  *      %FULL = time(FULL) / period
  49  *
  50  *                      Multiple CPUs
  51  *
  52  * The more tasks and available CPUs there are, the more work can be
  53  * performed concurrently. This means that the potential that can go
  54  * unrealized due to resource contention *also* scales with non-idle
  55  * tasks and CPUs.
  56  *
  57  * Consider a scenario where 257 number crunching tasks are trying to
  58  * run concurrently on 256 CPUs. If we simply aggregated the task
  59  * states, we would have to conclude a CPU SOME pressure number of
  60  * 100%, since *somebody* is waiting on a runqueue at all
  61  * times. However, that is clearly not the amount of contention the
  62  * workload is experiencing: only one out of 256 possible exceution
  63  * threads will be contended at any given time, or about 0.4%.
  64  *
  65  * Conversely, consider a scenario of 4 tasks and 4 CPUs where at any
  66  * given time *one* of the tasks is delayed due to a lack of memory.
  67  * Again, looking purely at the task state would yield a memory FULL
  68  * pressure number of 0%, since *somebody* is always making forward
  69  * progress. But again this wouldn't capture the amount of execution
  70  * potential lost, which is 1 out of 4 CPUs, or 25%.
  71  *
  72  * To calculate wasted potential (pressure) with multiple processors,
  73  * we have to base our calculation on the number of non-idle tasks in
  74  * conjunction with the number of available CPUs, which is the number
  75  * of potential execution threads. SOME becomes then the proportion of
  76  * delayed tasks to possibe threads, and FULL is the share of possible
  77  * threads that are unproductive due to delays:
  78  *
  79  *      threads = min(nr_nonidle_tasks, nr_cpus)
  80  *         SOME = min(nr_delayed_tasks / threads, 1)
  81  *         FULL = (threads - min(nr_running_tasks, threads)) / threads
  82  *
  83  * For the 257 number crunchers on 256 CPUs, this yields:
  84  *
  85  *      threads = min(257, 256)
  86  *         SOME = min(1 / 256, 1)             = 0.4%
  87  *         FULL = (256 - min(257, 256)) / 256 = 0%
  88  *
  89  * For the 1 out of 4 memory-delayed tasks, this yields:
  90  *
  91  *      threads = min(4, 4)
  92  *         SOME = min(1 / 4, 1)               = 25%
  93  *         FULL = (4 - min(3, 4)) / 4         = 25%
  94  *
  95  * [ Substitute nr_cpus with 1, and you can see that it's a natural
  96  *   extension of the single-CPU model. ]
  97  *
  98  *                      Implementation
  99  *
 100  * To assess the precise time spent in each such state, we would have
 101  * to freeze the system on task changes and start/stop the state
 102  * clocks accordingly. Obviously that doesn't scale in practice.
 103  *
 104  * Because the scheduler aims to distribute the compute load evenly
 105  * among the available CPUs, we can track task state locally to each
 106  * CPU and, at much lower frequency, extrapolate the global state for
 107  * the cumulative stall times and the running averages.
 108  *
 109  * For each runqueue, we track:
 110  *
 111  *         tSOME[cpu] = time(nr_delayed_tasks[cpu] != 0)
 112  *         tFULL[cpu] = time(nr_delayed_tasks[cpu] && !nr_running_tasks[cpu])
 113  *      tNONIDLE[cpu] = time(nr_nonidle_tasks[cpu] != 0)
 114  *
 115  * and then periodically aggregate:
 116  *
 117  *      tNONIDLE = sum(tNONIDLE[i])
 118  *
 119  *         tSOME = sum(tSOME[i] * tNONIDLE[i]) / tNONIDLE
 120  *         tFULL = sum(tFULL[i] * tNONIDLE[i]) / tNONIDLE
 121  *
 122  *         %SOME = tSOME / period
 123  *         %FULL = tFULL / period
 124  *
 125  * This gives us an approximation of pressure that is practical
 126  * cost-wise, yet way more sensitive and accurate than periodic
 127  * sampling of the aggregate task states would be.
 128  */
 129 
 130 #include "../workqueue_internal.h"
 131 #include <linux/sched/loadavg.h>
 132 #include <linux/seq_file.h>
 133 #include <linux/proc_fs.h>
 134 #include <linux/seqlock.h>
 135 #include <linux/uaccess.h>
 136 #include <linux/cgroup.h>
 137 #include <linux/module.h>
 138 #include <linux/sched.h>
 139 #include <linux/ctype.h>
 140 #include <linux/file.h>
 141 #include <linux/poll.h>
 142 #include <linux/psi.h>
 143 #include "sched.h"
 144 
 145 static int psi_bug __read_mostly;
 146 
 147 DEFINE_STATIC_KEY_FALSE(psi_disabled);
 148 
 149 #ifdef CONFIG_PSI_DEFAULT_DISABLED
 150 static bool psi_enable;
 151 #else
 152 static bool psi_enable = true;
 153 #endif
 154 static int __init setup_psi(char *str)
 155 {
 156         return kstrtobool(str, &psi_enable) == 0;
 157 }
 158 __setup("psi=", setup_psi);
 159 
 160 /* Running averages - we need to be higher-res than loadavg */
 161 #define PSI_FREQ        (2*HZ+1)        /* 2 sec intervals */
 162 #define EXP_10s         1677            /* 1/exp(2s/10s) as fixed-point */
 163 #define EXP_60s         1981            /* 1/exp(2s/60s) */
 164 #define EXP_300s        2034            /* 1/exp(2s/300s) */
 165 
 166 /* PSI trigger definitions */
 167 #define WINDOW_MIN_US 500000    /* Min window size is 500ms */
 168 #define WINDOW_MAX_US 10000000  /* Max window size is 10s */
 169 #define UPDATES_PER_WINDOW 10   /* 10 updates per window */
 170 
 171 /* Sampling frequency in nanoseconds */
 172 static u64 psi_period __read_mostly;
 173 
 174 /* System-level pressure and stall tracking */
 175 static DEFINE_PER_CPU(struct psi_group_cpu, system_group_pcpu);
 176 struct psi_group psi_system = {
 177         .pcpu = &system_group_pcpu,
 178 };
 179 
 180 static void psi_avgs_work(struct work_struct *work);
 181 
 182 static void group_init(struct psi_group *group)
 183 {
 184         int cpu;
 185 
 186         for_each_possible_cpu(cpu)
 187                 seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
 188         group->avg_last_update = sched_clock();
 189         group->avg_next_update = group->avg_last_update + psi_period;
 190         INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
 191         mutex_init(&group->avgs_lock);
 192         /* Init trigger-related members */
 193         atomic_set(&group->poll_scheduled, 0);
 194         mutex_init(&group->trigger_lock);
 195         INIT_LIST_HEAD(&group->triggers);
 196         memset(group->nr_triggers, 0, sizeof(group->nr_triggers));
 197         group->poll_states = 0;
 198         group->poll_min_period = U32_MAX;
 199         memset(group->polling_total, 0, sizeof(group->polling_total));
 200         group->polling_next_update = ULLONG_MAX;
 201         group->polling_until = 0;
 202         rcu_assign_pointer(group->poll_kworker, NULL);
 203 }
 204 
 205 void __init psi_init(void)
 206 {
 207         if (!psi_enable) {
 208                 static_branch_enable(&psi_disabled);
 209                 return;
 210         }
 211 
 212         psi_period = jiffies_to_nsecs(PSI_FREQ);
 213         group_init(&psi_system);
 214 }
 215 
 216 static bool test_state(unsigned int *tasks, enum psi_states state)
 217 {
 218         switch (state) {
 219         case PSI_IO_SOME:
 220                 return tasks[NR_IOWAIT];
 221         case PSI_IO_FULL:
 222                 return tasks[NR_IOWAIT] && !tasks[NR_RUNNING];
 223         case PSI_MEM_SOME:
 224                 return tasks[NR_MEMSTALL];
 225         case PSI_MEM_FULL:
 226                 return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
 227         case PSI_CPU_SOME:
 228                 return tasks[NR_RUNNING] > 1;
 229         case PSI_NONIDLE:
 230                 return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
 231                         tasks[NR_RUNNING];
 232         default:
 233                 return false;
 234         }
 235 }
 236 
 237 static void get_recent_times(struct psi_group *group, int cpu,
 238                              enum psi_aggregators aggregator, u32 *times,
 239                              u32 *pchanged_states)
 240 {
 241         struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
 242         u64 now, state_start;
 243         enum psi_states s;
 244         unsigned int seq;
 245         u32 state_mask;
 246 
 247         *pchanged_states = 0;
 248 
 249         /* Snapshot a coherent view of the CPU state */
 250         do {
 251                 seq = read_seqcount_begin(&groupc->seq);
 252                 now = cpu_clock(cpu);
 253                 memcpy(times, groupc->times, sizeof(groupc->times));
 254                 state_mask = groupc->state_mask;
 255                 state_start = groupc->state_start;
 256         } while (read_seqcount_retry(&groupc->seq, seq));
 257 
 258         /* Calculate state time deltas against the previous snapshot */
 259         for (s = 0; s < NR_PSI_STATES; s++) {
 260                 u32 delta;
 261                 /*
 262                  * In addition to already concluded states, we also
 263                  * incorporate currently active states on the CPU,
 264                  * since states may last for many sampling periods.
 265                  *
 266                  * This way we keep our delta sampling buckets small
 267                  * (u32) and our reported pressure close to what's
 268                  * actually happening.
 269                  */
 270                 if (state_mask & (1 << s))
 271                         times[s] += now - state_start;
 272 
 273                 delta = times[s] - groupc->times_prev[aggregator][s];
 274                 groupc->times_prev[aggregator][s] = times[s];
 275 
 276                 times[s] = delta;
 277                 if (delta)
 278                         *pchanged_states |= (1 << s);
 279         }
 280 }
 281 
 282 static void calc_avgs(unsigned long avg[3], int missed_periods,
 283                       u64 time, u64 period)
 284 {
 285         unsigned long pct;
 286 
 287         /* Fill in zeroes for periods of no activity */
 288         if (missed_periods) {
 289                 avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods);
 290                 avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods);
 291                 avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods);
 292         }
 293 
 294         /* Sample the most recent active period */
 295         pct = div_u64(time * 100, period);
 296         pct *= FIXED_1;
 297         avg[0] = calc_load(avg[0], EXP_10s, pct);
 298         avg[1] = calc_load(avg[1], EXP_60s, pct);
 299         avg[2] = calc_load(avg[2], EXP_300s, pct);
 300 }
 301 
 302 static void collect_percpu_times(struct psi_group *group,
 303                                  enum psi_aggregators aggregator,
 304                                  u32 *pchanged_states)
 305 {
 306         u64 deltas[NR_PSI_STATES - 1] = { 0, };
 307         unsigned long nonidle_total = 0;
 308         u32 changed_states = 0;
 309         int cpu;
 310         int s;
 311 
 312         /*
 313          * Collect the per-cpu time buckets and average them into a
 314          * single time sample that is normalized to wallclock time.
 315          *
 316          * For averaging, each CPU is weighted by its non-idle time in
 317          * the sampling period. This eliminates artifacts from uneven
 318          * loading, or even entirely idle CPUs.
 319          */
 320         for_each_possible_cpu(cpu) {
 321                 u32 times[NR_PSI_STATES];
 322                 u32 nonidle;
 323                 u32 cpu_changed_states;
 324 
 325                 get_recent_times(group, cpu, aggregator, times,
 326                                 &cpu_changed_states);
 327                 changed_states |= cpu_changed_states;
 328 
 329                 nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]);
 330                 nonidle_total += nonidle;
 331 
 332                 for (s = 0; s < PSI_NONIDLE; s++)
 333                         deltas[s] += (u64)times[s] * nonidle;
 334         }
 335 
 336         /*
 337          * Integrate the sample into the running statistics that are
 338          * reported to userspace: the cumulative stall times and the
 339          * decaying averages.
 340          *
 341          * Pressure percentages are sampled at PSI_FREQ. We might be
 342          * called more often when the user polls more frequently than
 343          * that; we might be called less often when there is no task
 344          * activity, thus no data, and clock ticks are sporadic. The
 345          * below handles both.
 346          */
 347 
 348         /* total= */
 349         for (s = 0; s < NR_PSI_STATES - 1; s++)
 350                 group->total[aggregator][s] +=
 351                                 div_u64(deltas[s], max(nonidle_total, 1UL));
 352 
 353         if (pchanged_states)
 354                 *pchanged_states = changed_states;
 355 }
 356 
 357 static u64 update_averages(struct psi_group *group, u64 now)
 358 {
 359         unsigned long missed_periods = 0;
 360         u64 expires, period;
 361         u64 avg_next_update;
 362         int s;
 363 
 364         /* avgX= */
 365         expires = group->avg_next_update;
 366         if (now - expires >= psi_period)
 367                 missed_periods = div_u64(now - expires, psi_period);
 368 
 369         /*
 370          * The periodic clock tick can get delayed for various
 371          * reasons, especially on loaded systems. To avoid clock
 372          * drift, we schedule the clock in fixed psi_period intervals.
 373          * But the deltas we sample out of the per-cpu buckets above
 374          * are based on the actual time elapsing between clock ticks.
 375          */
 376         avg_next_update = expires + ((1 + missed_periods) * psi_period);
 377         period = now - (group->avg_last_update + (missed_periods * psi_period));
 378         group->avg_last_update = now;
 379 
 380         for (s = 0; s < NR_PSI_STATES - 1; s++) {
 381                 u32 sample;
 382 
 383                 sample = group->total[PSI_AVGS][s] - group->avg_total[s];
 384                 /*
 385                  * Due to the lockless sampling of the time buckets,
 386                  * recorded time deltas can slip into the next period,
 387                  * which under full pressure can result in samples in
 388                  * excess of the period length.
 389                  *
 390                  * We don't want to report non-sensical pressures in
 391                  * excess of 100%, nor do we want to drop such events
 392                  * on the floor. Instead we punt any overage into the
 393                  * future until pressure subsides. By doing this we
 394                  * don't underreport the occurring pressure curve, we
 395                  * just report it delayed by one period length.
 396                  *
 397                  * The error isn't cumulative. As soon as another
 398                  * delta slips from a period P to P+1, by definition
 399                  * it frees up its time T in P.
 400                  */
 401                 if (sample > period)
 402                         sample = period;
 403                 group->avg_total[s] += sample;
 404                 calc_avgs(group->avg[s], missed_periods, sample, period);
 405         }
 406 
 407         return avg_next_update;
 408 }
 409 
 410 static void psi_avgs_work(struct work_struct *work)
 411 {
 412         struct delayed_work *dwork;
 413         struct psi_group *group;
 414         u32 changed_states;
 415         bool nonidle;
 416         u64 now;
 417 
 418         dwork = to_delayed_work(work);
 419         group = container_of(dwork, struct psi_group, avgs_work);
 420 
 421         mutex_lock(&group->avgs_lock);
 422 
 423         now = sched_clock();
 424 
 425         collect_percpu_times(group, PSI_AVGS, &changed_states);
 426         nonidle = changed_states & (1 << PSI_NONIDLE);
 427         /*
 428          * If there is task activity, periodically fold the per-cpu
 429          * times and feed samples into the running averages. If things
 430          * are idle and there is no data to process, stop the clock.
 431          * Once restarted, we'll catch up the running averages in one
 432          * go - see calc_avgs() and missed_periods.
 433          */
 434         if (now >= group->avg_next_update)
 435                 group->avg_next_update = update_averages(group, now);
 436 
 437         if (nonidle) {
 438                 schedule_delayed_work(dwork, nsecs_to_jiffies(
 439                                 group->avg_next_update - now) + 1);
 440         }
 441 
 442         mutex_unlock(&group->avgs_lock);
 443 }
 444 
 445 /* Trigger tracking window manupulations */
 446 static void window_reset(struct psi_window *win, u64 now, u64 value,
 447                          u64 prev_growth)
 448 {
 449         win->start_time = now;
 450         win->start_value = value;
 451         win->prev_growth = prev_growth;
 452 }
 453 
 454 /*
 455  * PSI growth tracking window update and growth calculation routine.
 456  *
 457  * This approximates a sliding tracking window by interpolating
 458  * partially elapsed windows using historical growth data from the
 459  * previous intervals. This minimizes memory requirements (by not storing
 460  * all the intermediate values in the previous window) and simplifies
 461  * the calculations. It works well because PSI signal changes only in
 462  * positive direction and over relatively small window sizes the growth
 463  * is close to linear.
 464  */
 465 static u64 window_update(struct psi_window *win, u64 now, u64 value)
 466 {
 467         u64 elapsed;
 468         u64 growth;
 469 
 470         elapsed = now - win->start_time;
 471         growth = value - win->start_value;
 472         /*
 473          * After each tracking window passes win->start_value and
 474          * win->start_time get reset and win->prev_growth stores
 475          * the average per-window growth of the previous window.
 476          * win->prev_growth is then used to interpolate additional
 477          * growth from the previous window assuming it was linear.
 478          */
 479         if (elapsed > win->size)
 480                 window_reset(win, now, value, growth);
 481         else {
 482                 u32 remaining;
 483 
 484                 remaining = win->size - elapsed;
 485                 growth += div64_u64(win->prev_growth * remaining, win->size);
 486         }
 487 
 488         return growth;
 489 }
 490 
 491 static void init_triggers(struct psi_group *group, u64 now)
 492 {
 493         struct psi_trigger *t;
 494 
 495         list_for_each_entry(t, &group->triggers, node)
 496                 window_reset(&t->win, now,
 497                                 group->total[PSI_POLL][t->state], 0);
 498         memcpy(group->polling_total, group->total[PSI_POLL],
 499                    sizeof(group->polling_total));
 500         group->polling_next_update = now + group->poll_min_period;
 501 }
 502 
 503 static u64 update_triggers(struct psi_group *group, u64 now)
 504 {
 505         struct psi_trigger *t;
 506         bool new_stall = false;
 507         u64 *total = group->total[PSI_POLL];
 508 
 509         /*
 510          * On subsequent updates, calculate growth deltas and let
 511          * watchers know when their specified thresholds are exceeded.
 512          */
 513         list_for_each_entry(t, &group->triggers, node) {
 514                 u64 growth;
 515 
 516                 /* Check for stall activity */
 517                 if (group->polling_total[t->state] == total[t->state])
 518                         continue;
 519 
 520                 /*
 521                  * Multiple triggers might be looking at the same state,
 522                  * remember to update group->polling_total[] once we've
 523                  * been through all of them. Also remember to extend the
 524                  * polling time if we see new stall activity.
 525                  */
 526                 new_stall = true;
 527 
 528                 /* Calculate growth since last update */
 529                 growth = window_update(&t->win, now, total[t->state]);
 530                 if (growth < t->threshold)
 531                         continue;
 532 
 533                 /* Limit event signaling to once per window */
 534                 if (now < t->last_event_time + t->win.size)
 535                         continue;
 536 
 537                 /* Generate an event */
 538                 if (cmpxchg(&t->event, 0, 1) == 0)
 539                         wake_up_interruptible(&t->event_wait);
 540                 t->last_event_time = now;
 541         }
 542 
 543         if (new_stall)
 544                 memcpy(group->polling_total, total,
 545                                 sizeof(group->polling_total));
 546 
 547         return now + group->poll_min_period;
 548 }
 549 
 550 /*
 551  * Schedule polling if it's not already scheduled. It's safe to call even from
 552  * hotpath because even though kthread_queue_delayed_work takes worker->lock
 553  * spinlock that spinlock is never contended due to poll_scheduled atomic
 554  * preventing such competition.
 555  */
 556 static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay)
 557 {
 558         struct kthread_worker *kworker;
 559 
 560         /* Do not reschedule if already scheduled */
 561         if (atomic_cmpxchg(&group->poll_scheduled, 0, 1) != 0)
 562                 return;
 563 
 564         rcu_read_lock();
 565 
 566         kworker = rcu_dereference(group->poll_kworker);
 567         /*
 568          * kworker might be NULL in case psi_trigger_destroy races with
 569          * psi_task_change (hotpath) which can't use locks
 570          */
 571         if (likely(kworker))
 572                 kthread_queue_delayed_work(kworker, &group->poll_work, delay);
 573         else
 574                 atomic_set(&group->poll_scheduled, 0);
 575 
 576         rcu_read_unlock();
 577 }
 578 
 579 static void psi_poll_work(struct kthread_work *work)
 580 {
 581         struct kthread_delayed_work *dwork;
 582         struct psi_group *group;
 583         u32 changed_states;
 584         u64 now;
 585 
 586         dwork = container_of(work, struct kthread_delayed_work, work);
 587         group = container_of(dwork, struct psi_group, poll_work);
 588 
 589         atomic_set(&group->poll_scheduled, 0);
 590 
 591         mutex_lock(&group->trigger_lock);
 592 
 593         now = sched_clock();
 594 
 595         collect_percpu_times(group, PSI_POLL, &changed_states);
 596 
 597         if (changed_states & group->poll_states) {
 598                 /* Initialize trigger windows when entering polling mode */
 599                 if (now > group->polling_until)
 600                         init_triggers(group, now);
 601 
 602                 /*
 603                  * Keep the monitor active for at least the duration of the
 604                  * minimum tracking window as long as monitor states are
 605                  * changing.
 606                  */
 607                 group->polling_until = now +
 608                         group->poll_min_period * UPDATES_PER_WINDOW;
 609         }
 610 
 611         if (now > group->polling_until) {
 612                 group->polling_next_update = ULLONG_MAX;
 613                 goto out;
 614         }
 615 
 616         if (now >= group->polling_next_update)
 617                 group->polling_next_update = update_triggers(group, now);
 618 
 619         psi_schedule_poll_work(group,
 620                 nsecs_to_jiffies(group->polling_next_update - now) + 1);
 621 
 622 out:
 623         mutex_unlock(&group->trigger_lock);
 624 }
 625 
 626 static void record_times(struct psi_group_cpu *groupc, int cpu,
 627                          bool memstall_tick)
 628 {
 629         u32 delta;
 630         u64 now;
 631 
 632         now = cpu_clock(cpu);
 633         delta = now - groupc->state_start;
 634         groupc->state_start = now;
 635 
 636         if (groupc->state_mask & (1 << PSI_IO_SOME)) {
 637                 groupc->times[PSI_IO_SOME] += delta;
 638                 if (groupc->state_mask & (1 << PSI_IO_FULL))
 639                         groupc->times[PSI_IO_FULL] += delta;
 640         }
 641 
 642         if (groupc->state_mask & (1 << PSI_MEM_SOME)) {
 643                 groupc->times[PSI_MEM_SOME] += delta;
 644                 if (groupc->state_mask & (1 << PSI_MEM_FULL))
 645                         groupc->times[PSI_MEM_FULL] += delta;
 646                 else if (memstall_tick) {
 647                         u32 sample;
 648                         /*
 649                          * Since we care about lost potential, a
 650                          * memstall is FULL when there are no other
 651                          * working tasks, but also when the CPU is
 652                          * actively reclaiming and nothing productive
 653                          * could run even if it were runnable.
 654                          *
 655                          * When the timer tick sees a reclaiming CPU,
 656                          * regardless of runnable tasks, sample a FULL
 657                          * tick (or less if it hasn't been a full tick
 658                          * since the last state change).
 659                          */
 660                         sample = min(delta, (u32)jiffies_to_nsecs(1));
 661                         groupc->times[PSI_MEM_FULL] += sample;
 662                 }
 663         }
 664 
 665         if (groupc->state_mask & (1 << PSI_CPU_SOME))
 666                 groupc->times[PSI_CPU_SOME] += delta;
 667 
 668         if (groupc->state_mask & (1 << PSI_NONIDLE))
 669                 groupc->times[PSI_NONIDLE] += delta;
 670 }
 671 
 672 static u32 psi_group_change(struct psi_group *group, int cpu,
 673                             unsigned int clear, unsigned int set)
 674 {
 675         struct psi_group_cpu *groupc;
 676         unsigned int t, m;
 677         enum psi_states s;
 678         u32 state_mask = 0;
 679 
 680         groupc = per_cpu_ptr(group->pcpu, cpu);
 681 
 682         /*
 683          * First we assess the aggregate resource states this CPU's
 684          * tasks have been in since the last change, and account any
 685          * SOME and FULL time these may have resulted in.
 686          *
 687          * Then we update the task counts according to the state
 688          * change requested through the @clear and @set bits.
 689          */
 690         write_seqcount_begin(&groupc->seq);
 691 
 692         record_times(groupc, cpu, false);
 693 
 694         for (t = 0, m = clear; m; m &= ~(1 << t), t++) {
 695                 if (!(m & (1 << t)))
 696                         continue;
 697                 if (groupc->tasks[t] == 0 && !psi_bug) {
 698                         printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u] clear=%x set=%x\n",
 699                                         cpu, t, groupc->tasks[0],
 700                                         groupc->tasks[1], groupc->tasks[2],
 701                                         clear, set);
 702                         psi_bug = 1;
 703                 }
 704                 groupc->tasks[t]--;
 705         }
 706 
 707         for (t = 0; set; set &= ~(1 << t), t++)
 708                 if (set & (1 << t))
 709                         groupc->tasks[t]++;
 710 
 711         /* Calculate state mask representing active states */
 712         for (s = 0; s < NR_PSI_STATES; s++) {
 713                 if (test_state(groupc->tasks, s))
 714                         state_mask |= (1 << s);
 715         }
 716         groupc->state_mask = state_mask;
 717 
 718         write_seqcount_end(&groupc->seq);
 719 
 720         return state_mask;
 721 }
 722 
 723 static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
 724 {
 725 #ifdef CONFIG_CGROUPS
 726         struct cgroup *cgroup = NULL;
 727 
 728         if (!*iter)
 729                 cgroup = task->cgroups->dfl_cgrp;
 730         else if (*iter == &psi_system)
 731                 return NULL;
 732         else
 733                 cgroup = cgroup_parent(*iter);
 734 
 735         if (cgroup && cgroup_parent(cgroup)) {
 736                 *iter = cgroup;
 737                 return cgroup_psi(cgroup);
 738         }
 739 #else
 740         if (*iter)
 741                 return NULL;
 742 #endif
 743         *iter = &psi_system;
 744         return &psi_system;
 745 }
 746 
 747 void psi_task_change(struct task_struct *task, int clear, int set)
 748 {
 749         int cpu = task_cpu(task);
 750         struct psi_group *group;
 751         bool wake_clock = true;
 752         void *iter = NULL;
 753 
 754         if (!task->pid)
 755                 return;
 756 
 757         if (((task->psi_flags & set) ||
 758              (task->psi_flags & clear) != clear) &&
 759             !psi_bug) {
 760                 printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
 761                                 task->pid, task->comm, cpu,
 762                                 task->psi_flags, clear, set);
 763                 psi_bug = 1;
 764         }
 765 
 766         task->psi_flags &= ~clear;
 767         task->psi_flags |= set;
 768 
 769         /*
 770          * Periodic aggregation shuts off if there is a period of no
 771          * task changes, so we wake it back up if necessary. However,
 772          * don't do this if the task change is the aggregation worker
 773          * itself going to sleep, or we'll ping-pong forever.
 774          */
 775         if (unlikely((clear & TSK_RUNNING) &&
 776                      (task->flags & PF_WQ_WORKER) &&
 777                      wq_worker_last_func(task) == psi_avgs_work))
 778                 wake_clock = false;
 779 
 780         while ((group = iterate_groups(task, &iter))) {
 781                 u32 state_mask = psi_group_change(group, cpu, clear, set);
 782 
 783                 if (state_mask & group->poll_states)
 784                         psi_schedule_poll_work(group, 1);
 785 
 786                 if (wake_clock && !delayed_work_pending(&group->avgs_work))
 787                         schedule_delayed_work(&group->avgs_work, PSI_FREQ);
 788         }
 789 }
 790 
 791 void psi_memstall_tick(struct task_struct *task, int cpu)
 792 {
 793         struct psi_group *group;
 794         void *iter = NULL;
 795 
 796         while ((group = iterate_groups(task, &iter))) {
 797                 struct psi_group_cpu *groupc;
 798 
 799                 groupc = per_cpu_ptr(group->pcpu, cpu);
 800                 write_seqcount_begin(&groupc->seq);
 801                 record_times(groupc, cpu, true);
 802                 write_seqcount_end(&groupc->seq);
 803         }
 804 }
 805 
 806 /**
 807  * psi_memstall_enter - mark the beginning of a memory stall section
 808  * @flags: flags to handle nested sections
 809  *
 810  * Marks the calling task as being stalled due to a lack of memory,
 811  * such as waiting for a refault or performing reclaim.
 812  */
 813 void psi_memstall_enter(unsigned long *flags)
 814 {
 815         struct rq_flags rf;
 816         struct rq *rq;
 817 
 818         if (static_branch_likely(&psi_disabled))
 819                 return;
 820 
 821         *flags = current->flags & PF_MEMSTALL;
 822         if (*flags)
 823                 return;
 824         /*
 825          * PF_MEMSTALL setting & accounting needs to be atomic wrt
 826          * changes to the task's scheduling state, otherwise we can
 827          * race with CPU migration.
 828          */
 829         rq = this_rq_lock_irq(&rf);
 830 
 831         current->flags |= PF_MEMSTALL;
 832         psi_task_change(current, 0, TSK_MEMSTALL);
 833 
 834         rq_unlock_irq(rq, &rf);
 835 }
 836 
 837 /**
 838  * psi_memstall_leave - mark the end of an memory stall section
 839  * @flags: flags to handle nested memdelay sections
 840  *
 841  * Marks the calling task as no longer stalled due to lack of memory.
 842  */
 843 void psi_memstall_leave(unsigned long *flags)
 844 {
 845         struct rq_flags rf;
 846         struct rq *rq;
 847 
 848         if (static_branch_likely(&psi_disabled))
 849                 return;
 850 
 851         if (*flags)
 852                 return;
 853         /*
 854          * PF_MEMSTALL clearing & accounting needs to be atomic wrt
 855          * changes to the task's scheduling state, otherwise we could
 856          * race with CPU migration.
 857          */
 858         rq = this_rq_lock_irq(&rf);
 859 
 860         current->flags &= ~PF_MEMSTALL;
 861         psi_task_change(current, TSK_MEMSTALL, 0);
 862 
 863         rq_unlock_irq(rq, &rf);
 864 }
 865 
 866 #ifdef CONFIG_CGROUPS
 867 int psi_cgroup_alloc(struct cgroup *cgroup)
 868 {
 869         if (static_branch_likely(&psi_disabled))
 870                 return 0;
 871 
 872         cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
 873         if (!cgroup->psi.pcpu)
 874                 return -ENOMEM;
 875         group_init(&cgroup->psi);
 876         return 0;
 877 }
 878 
 879 void psi_cgroup_free(struct cgroup *cgroup)
 880 {
 881         if (static_branch_likely(&psi_disabled))
 882                 return;
 883 
 884         cancel_delayed_work_sync(&cgroup->psi.avgs_work);
 885         free_percpu(cgroup->psi.pcpu);
 886         /* All triggers must be removed by now */
 887         WARN_ONCE(cgroup->psi.poll_states, "psi: trigger leak\n");
 888 }
 889 
 890 /**
 891  * cgroup_move_task - move task to a different cgroup
 892  * @task: the task
 893  * @to: the target css_set
 894  *
 895  * Move task to a new cgroup and safely migrate its associated stall
 896  * state between the different groups.
 897  *
 898  * This function acquires the task's rq lock to lock out concurrent
 899  * changes to the task's scheduling state and - in case the task is
 900  * running - concurrent changes to its stall state.
 901  */
 902 void cgroup_move_task(struct task_struct *task, struct css_set *to)
 903 {
 904         unsigned int task_flags = 0;
 905         struct rq_flags rf;
 906         struct rq *rq;
 907 
 908         if (static_branch_likely(&psi_disabled)) {
 909                 /*
 910                  * Lame to do this here, but the scheduler cannot be locked
 911                  * from the outside, so we move cgroups from inside sched/.
 912                  */
 913                 rcu_assign_pointer(task->cgroups, to);
 914                 return;
 915         }
 916 
 917         rq = task_rq_lock(task, &rf);
 918 
 919         if (task_on_rq_queued(task))
 920                 task_flags = TSK_RUNNING;
 921         else if (task->in_iowait)
 922                 task_flags = TSK_IOWAIT;
 923 
 924         if (task->flags & PF_MEMSTALL)
 925                 task_flags |= TSK_MEMSTALL;
 926 
 927         if (task_flags)
 928                 psi_task_change(task, task_flags, 0);
 929 
 930         /* See comment above */
 931         rcu_assign_pointer(task->cgroups, to);
 932 
 933         if (task_flags)
 934                 psi_task_change(task, 0, task_flags);
 935 
 936         task_rq_unlock(rq, task, &rf);
 937 }
 938 #endif /* CONFIG_CGROUPS */
 939 
 940 int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
 941 {
 942         int full;
 943         u64 now;
 944 
 945         if (static_branch_likely(&psi_disabled))
 946                 return -EOPNOTSUPP;
 947 
 948         /* Update averages before reporting them */
 949         mutex_lock(&group->avgs_lock);
 950         now = sched_clock();
 951         collect_percpu_times(group, PSI_AVGS, NULL);
 952         if (now >= group->avg_next_update)
 953                 group->avg_next_update = update_averages(group, now);
 954         mutex_unlock(&group->avgs_lock);
 955 
 956         for (full = 0; full < 2 - (res == PSI_CPU); full++) {
 957                 unsigned long avg[3];
 958                 u64 total;
 959                 int w;
 960 
 961                 for (w = 0; w < 3; w++)
 962                         avg[w] = group->avg[res * 2 + full][w];
 963                 total = div_u64(group->total[PSI_AVGS][res * 2 + full],
 964                                 NSEC_PER_USEC);
 965 
 966                 seq_printf(m, "%s avg10=%lu.%02lu avg60=%lu.%02lu avg300=%lu.%02lu total=%llu\n",
 967                            full ? "full" : "some",
 968                            LOAD_INT(avg[0]), LOAD_FRAC(avg[0]),
 969                            LOAD_INT(avg[1]), LOAD_FRAC(avg[1]),
 970                            LOAD_INT(avg[2]), LOAD_FRAC(avg[2]),
 971                            total);
 972         }
 973 
 974         return 0;
 975 }
 976 
 977 static int psi_io_show(struct seq_file *m, void *v)
 978 {
 979         return psi_show(m, &psi_system, PSI_IO);
 980 }
 981 
 982 static int psi_memory_show(struct seq_file *m, void *v)
 983 {
 984         return psi_show(m, &psi_system, PSI_MEM);
 985 }
 986 
 987 static int psi_cpu_show(struct seq_file *m, void *v)
 988 {
 989         return psi_show(m, &psi_system, PSI_CPU);
 990 }
 991 
 992 static int psi_io_open(struct inode *inode, struct file *file)
 993 {
 994         return single_open(file, psi_io_show, NULL);
 995 }
 996 
 997 static int psi_memory_open(struct inode *inode, struct file *file)
 998 {
 999         return single_open(file, psi_memory_show, NULL);
1000 }
1001 
1002 static int psi_cpu_open(struct inode *inode, struct file *file)
1003 {
1004         return single_open(file, psi_cpu_show, NULL);
1005 }
1006 
1007 struct psi_trigger *psi_trigger_create(struct psi_group *group,
1008                         char *buf, size_t nbytes, enum psi_res res)
1009 {
1010         struct psi_trigger *t;
1011         enum psi_states state;
1012         u32 threshold_us;
1013         u32 window_us;
1014 
1015         if (static_branch_likely(&psi_disabled))
1016                 return ERR_PTR(-EOPNOTSUPP);
1017 
1018         if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2)
1019                 state = PSI_IO_SOME + res * 2;
1020         else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2)
1021                 state = PSI_IO_FULL + res * 2;
1022         else
1023                 return ERR_PTR(-EINVAL);
1024 
1025         if (state >= PSI_NONIDLE)
1026                 return ERR_PTR(-EINVAL);
1027 
1028         if (window_us < WINDOW_MIN_US ||
1029                 window_us > WINDOW_MAX_US)
1030                 return ERR_PTR(-EINVAL);
1031 
1032         /* Check threshold */
1033         if (threshold_us == 0 || threshold_us > window_us)
1034                 return ERR_PTR(-EINVAL);
1035 
1036         t = kmalloc(sizeof(*t), GFP_KERNEL);
1037         if (!t)
1038                 return ERR_PTR(-ENOMEM);
1039 
1040         t->group = group;
1041         t->state = state;
1042         t->threshold = threshold_us * NSEC_PER_USEC;
1043         t->win.size = window_us * NSEC_PER_USEC;
1044         window_reset(&t->win, 0, 0, 0);
1045 
1046         t->event = 0;
1047         t->last_event_time = 0;
1048         init_waitqueue_head(&t->event_wait);
1049         kref_init(&t->refcount);
1050 
1051         mutex_lock(&group->trigger_lock);
1052 
1053         if (!rcu_access_pointer(group->poll_kworker)) {
1054                 struct sched_param param = {
1055                         .sched_priority = 1,
1056                 };
1057                 struct kthread_worker *kworker;
1058 
1059                 kworker = kthread_create_worker(0, "psimon");
1060                 if (IS_ERR(kworker)) {
1061                         kfree(t);
1062                         mutex_unlock(&group->trigger_lock);
1063                         return ERR_CAST(kworker);
1064                 }
1065                 sched_setscheduler_nocheck(kworker->task, SCHED_FIFO, &param);
1066                 kthread_init_delayed_work(&group->poll_work,
1067                                 psi_poll_work);
1068                 rcu_assign_pointer(group->poll_kworker, kworker);
1069         }
1070 
1071         list_add(&t->node, &group->triggers);
1072         group->poll_min_period = min(group->poll_min_period,
1073                 div_u64(t->win.size, UPDATES_PER_WINDOW));
1074         group->nr_triggers[t->state]++;
1075         group->poll_states |= (1 << t->state);
1076 
1077         mutex_unlock(&group->trigger_lock);
1078 
1079         return t;
1080 }
1081 
1082 static void psi_trigger_destroy(struct kref *ref)
1083 {
1084         struct psi_trigger *t = container_of(ref, struct psi_trigger, refcount);
1085         struct psi_group *group = t->group;
1086         struct kthread_worker *kworker_to_destroy = NULL;
1087 
1088         if (static_branch_likely(&psi_disabled))
1089                 return;
1090 
1091         /*
1092          * Wakeup waiters to stop polling. Can happen if cgroup is deleted
1093          * from under a polling process.
1094          */
1095         wake_up_interruptible(&t->event_wait);
1096 
1097         mutex_lock(&group->trigger_lock);
1098 
1099         if (!list_empty(&t->node)) {
1100                 struct psi_trigger *tmp;
1101                 u64 period = ULLONG_MAX;
1102 
1103                 list_del(&t->node);
1104                 group->nr_triggers[t->state]--;
1105                 if (!group->nr_triggers[t->state])
1106                         group->poll_states &= ~(1 << t->state);
1107                 /* reset min update period for the remaining triggers */
1108                 list_for_each_entry(tmp, &group->triggers, node)
1109                         period = min(period, div_u64(tmp->win.size,
1110                                         UPDATES_PER_WINDOW));
1111                 group->poll_min_period = period;
1112                 /* Destroy poll_kworker when the last trigger is destroyed */
1113                 if (group->poll_states == 0) {
1114                         group->polling_until = 0;
1115                         kworker_to_destroy = rcu_dereference_protected(
1116                                         group->poll_kworker,
1117                                         lockdep_is_held(&group->trigger_lock));
1118                         rcu_assign_pointer(group->poll_kworker, NULL);
1119                 }
1120         }
1121 
1122         mutex_unlock(&group->trigger_lock);
1123 
1124         /*
1125          * Wait for both *trigger_ptr from psi_trigger_replace and
1126          * poll_kworker RCUs to complete their read-side critical sections
1127          * before destroying the trigger and optionally the poll_kworker
1128          */
1129         synchronize_rcu();
1130         /*
1131          * Destroy the kworker after releasing trigger_lock to prevent a
1132          * deadlock while waiting for psi_poll_work to acquire trigger_lock
1133          */
1134         if (kworker_to_destroy) {
1135                 /*
1136                  * After the RCU grace period has expired, the worker
1137                  * can no longer be found through group->poll_kworker.
1138                  * But it might have been already scheduled before
1139                  * that - deschedule it cleanly before destroying it.
1140                  */
1141                 kthread_cancel_delayed_work_sync(&group->poll_work);
1142                 atomic_set(&group->poll_scheduled, 0);
1143 
1144                 kthread_destroy_worker(kworker_to_destroy);
1145         }
1146         kfree(t);
1147 }
1148 
1149 void psi_trigger_replace(void **trigger_ptr, struct psi_trigger *new)
1150 {
1151         struct psi_trigger *old = *trigger_ptr;
1152 
1153         if (static_branch_likely(&psi_disabled))
1154                 return;
1155 
1156         rcu_assign_pointer(*trigger_ptr, new);
1157         if (old)
1158                 kref_put(&old->refcount, psi_trigger_destroy);
1159 }
1160 
1161 __poll_t psi_trigger_poll(void **trigger_ptr,
1162                                 struct file *file, poll_table *wait)
1163 {
1164         __poll_t ret = DEFAULT_POLLMASK;
1165         struct psi_trigger *t;
1166 
1167         if (static_branch_likely(&psi_disabled))
1168                 return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
1169 
1170         rcu_read_lock();
1171 
1172         t = rcu_dereference(*(void __rcu __force **)trigger_ptr);
1173         if (!t) {
1174                 rcu_read_unlock();
1175                 return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
1176         }
1177         kref_get(&t->refcount);
1178 
1179         rcu_read_unlock();
1180 
1181         poll_wait(file, &t->event_wait, wait);
1182 
1183         if (cmpxchg(&t->event, 1, 0) == 1)
1184                 ret |= EPOLLPRI;
1185 
1186         kref_put(&t->refcount, psi_trigger_destroy);
1187 
1188         return ret;
1189 }
1190 
1191 static ssize_t psi_write(struct file *file, const char __user *user_buf,
1192                          size_t nbytes, enum psi_res res)
1193 {
1194         char buf[32];
1195         size_t buf_size;
1196         struct seq_file *seq;
1197         struct psi_trigger *new;
1198 
1199         if (static_branch_likely(&psi_disabled))
1200                 return -EOPNOTSUPP;
1201 
1202         if (!nbytes)
1203                 return -EINVAL;
1204 
1205         buf_size = min(nbytes, sizeof(buf));
1206         if (copy_from_user(buf, user_buf, buf_size))
1207                 return -EFAULT;
1208 
1209         buf[buf_size - 1] = '\0';
1210 
1211         new = psi_trigger_create(&psi_system, buf, nbytes, res);
1212         if (IS_ERR(new))
1213                 return PTR_ERR(new);
1214 
1215         seq = file->private_data;
1216         /* Take seq->lock to protect seq->private from concurrent writes */
1217         mutex_lock(&seq->lock);
1218         psi_trigger_replace(&seq->private, new);
1219         mutex_unlock(&seq->lock);
1220 
1221         return nbytes;
1222 }
1223 
1224 static ssize_t psi_io_write(struct file *file, const char __user *user_buf,
1225                             size_t nbytes, loff_t *ppos)
1226 {
1227         return psi_write(file, user_buf, nbytes, PSI_IO);
1228 }
1229 
1230 static ssize_t psi_memory_write(struct file *file, const char __user *user_buf,
1231                                 size_t nbytes, loff_t *ppos)
1232 {
1233         return psi_write(file, user_buf, nbytes, PSI_MEM);
1234 }
1235 
1236 static ssize_t psi_cpu_write(struct file *file, const char __user *user_buf,
1237                              size_t nbytes, loff_t *ppos)
1238 {
1239         return psi_write(file, user_buf, nbytes, PSI_CPU);
1240 }
1241 
1242 static __poll_t psi_fop_poll(struct file *file, poll_table *wait)
1243 {
1244         struct seq_file *seq = file->private_data;
1245 
1246         return psi_trigger_poll(&seq->private, file, wait);
1247 }
1248 
1249 static int psi_fop_release(struct inode *inode, struct file *file)
1250 {
1251         struct seq_file *seq = file->private_data;
1252 
1253         psi_trigger_replace(&seq->private, NULL);
1254         return single_release(inode, file);
1255 }
1256 
1257 static const struct file_operations psi_io_fops = {
1258         .open           = psi_io_open,
1259         .read           = seq_read,
1260         .llseek         = seq_lseek,
1261         .write          = psi_io_write,
1262         .poll           = psi_fop_poll,
1263         .release        = psi_fop_release,
1264 };
1265 
1266 static const struct file_operations psi_memory_fops = {
1267         .open           = psi_memory_open,
1268         .read           = seq_read,
1269         .llseek         = seq_lseek,
1270         .write          = psi_memory_write,
1271         .poll           = psi_fop_poll,
1272         .release        = psi_fop_release,
1273 };
1274 
1275 static const struct file_operations psi_cpu_fops = {
1276         .open           = psi_cpu_open,
1277         .read           = seq_read,
1278         .llseek         = seq_lseek,
1279         .write          = psi_cpu_write,
1280         .poll           = psi_fop_poll,
1281         .release        = psi_fop_release,
1282 };
1283 
1284 static int __init psi_proc_init(void)
1285 {
1286         proc_mkdir("pressure", NULL);
1287         proc_create("pressure/io", 0, NULL, &psi_io_fops);
1288         proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
1289         proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
1290         return 0;
1291 }
1292 module_init(psi_proc_init);
/* [<][>][^][v][top][bottom][index][help] */
root/kernel/sched/psi.c

DEFINITIONS
