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| -rw-r--r-- | kernel/sched/psi.c | 1665 |
1 files changed, 1665 insertions, 0 deletions
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c new file mode 100644 index 0000000000..1d0f634725 --- /dev/null +++ b/kernel/sched/psi.c @@ -0,0 +1,1665 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Pressure stall information for CPU, memory and IO + * + * Copyright (c) 2018 Facebook, Inc. + * Author: Johannes Weiner <hannes@cmpxchg.org> + * + * Polling support by Suren Baghdasaryan <surenb@google.com> + * Copyright (c) 2018 Google, Inc. + * + * When CPU, memory and IO are contended, tasks experience delays that + * reduce throughput and introduce latencies into the workload. Memory + * and IO contention, in addition, can cause a full loss of forward + * progress in which the CPU goes idle. + * + * This code aggregates individual task delays into resource pressure + * metrics that indicate problems with both workload health and + * resource utilization. + * + * Model + * + * The time in which a task can execute on a CPU is our baseline for + * productivity. Pressure expresses the amount of time in which this + * potential cannot be realized due to resource contention. + * + * This concept of productivity has two components: the workload and + * the CPU. To measure the impact of pressure on both, we define two + * contention states for a resource: SOME and FULL. + * + * In the SOME state of a given resource, one or more tasks are + * delayed on that resource. This affects the workload's ability to + * perform work, but the CPU may still be executing other tasks. + * + * In the FULL state of a given resource, all non-idle tasks are + * delayed on that resource such that nobody is advancing and the CPU + * goes idle. This leaves both workload and CPU unproductive. + * + * SOME = nr_delayed_tasks != 0 + * FULL = nr_delayed_tasks != 0 && nr_productive_tasks == 0 + * + * What it means for a task to be productive is defined differently + * for each resource. For IO, productive means a running task. For + * memory, productive means a running task that isn't a reclaimer. For + * CPU, productive means an oncpu task. + * + * Naturally, the FULL state doesn't exist for the CPU resource at the + * system level, but exist at the cgroup level. At the cgroup level, + * FULL means all non-idle tasks in the cgroup are delayed on the CPU + * resource which is being used by others outside of the cgroup or + * throttled by the cgroup cpu.max configuration. + * + * The percentage of wallclock time spent in those compound stall + * states gives pressure numbers between 0 and 100 for each resource, + * where the SOME percentage indicates workload slowdowns and the FULL + * percentage indicates reduced CPU utilization: + * + * %SOME = time(SOME) / period + * %FULL = time(FULL) / period + * + * Multiple CPUs + * + * The more tasks and available CPUs there are, the more work can be + * performed concurrently. This means that the potential that can go + * unrealized due to resource contention *also* scales with non-idle + * tasks and CPUs. + * + * Consider a scenario where 257 number crunching tasks are trying to + * run concurrently on 256 CPUs. If we simply aggregated the task + * states, we would have to conclude a CPU SOME pressure number of + * 100%, since *somebody* is waiting on a runqueue at all + * times. However, that is clearly not the amount of contention the + * workload is experiencing: only one out of 256 possible execution + * threads will be contended at any given time, or about 0.4%. + * + * Conversely, consider a scenario of 4 tasks and 4 CPUs where at any + * given time *one* of the tasks is delayed due to a lack of memory. + * Again, looking purely at the task state would yield a memory FULL + * pressure number of 0%, since *somebody* is always making forward + * progress. But again this wouldn't capture the amount of execution + * potential lost, which is 1 out of 4 CPUs, or 25%. + * + * To calculate wasted potential (pressure) with multiple processors, + * we have to base our calculation on the number of non-idle tasks in + * conjunction with the number of available CPUs, which is the number + * of potential execution threads. SOME becomes then the proportion of + * delayed tasks to possible threads, and FULL is the share of possible + * threads that are unproductive due to delays: + * + * threads = min(nr_nonidle_tasks, nr_cpus) + * SOME = min(nr_delayed_tasks / threads, 1) + * FULL = (threads - min(nr_productive_tasks, threads)) / threads + * + * For the 257 number crunchers on 256 CPUs, this yields: + * + * threads = min(257, 256) + * SOME = min(1 / 256, 1) = 0.4% + * FULL = (256 - min(256, 256)) / 256 = 0% + * + * For the 1 out of 4 memory-delayed tasks, this yields: + * + * threads = min(4, 4) + * SOME = min(1 / 4, 1) = 25% + * FULL = (4 - min(3, 4)) / 4 = 25% + * + * [ Substitute nr_cpus with 1, and you can see that it's a natural + * extension of the single-CPU model. ] + * + * Implementation + * + * To assess the precise time spent in each such state, we would have + * to freeze the system on task changes and start/stop the state + * clocks accordingly. Obviously that doesn't scale in practice. + * + * Because the scheduler aims to distribute the compute load evenly + * among the available CPUs, we can track task state locally to each + * CPU and, at much lower frequency, extrapolate the global state for + * the cumulative stall times and the running averages. + * + * For each runqueue, we track: + * + * tSOME[cpu] = time(nr_delayed_tasks[cpu] != 0) + * tFULL[cpu] = time(nr_delayed_tasks[cpu] && !nr_productive_tasks[cpu]) + * tNONIDLE[cpu] = time(nr_nonidle_tasks[cpu] != 0) + * + * and then periodically aggregate: + * + * tNONIDLE = sum(tNONIDLE[i]) + * + * tSOME = sum(tSOME[i] * tNONIDLE[i]) / tNONIDLE + * tFULL = sum(tFULL[i] * tNONIDLE[i]) / tNONIDLE + * + * %SOME = tSOME / period + * %FULL = tFULL / period + * + * This gives us an approximation of pressure that is practical + * cost-wise, yet way more sensitive and accurate than periodic + * sampling of the aggregate task states would be. + */ + +static int psi_bug __read_mostly; + +DEFINE_STATIC_KEY_FALSE(psi_disabled); +static DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled); + +#ifdef CONFIG_PSI_DEFAULT_DISABLED +static bool psi_enable; +#else +static bool psi_enable = true; +#endif +static int __init setup_psi(char *str) +{ + return kstrtobool(str, &psi_enable) == 0; +} +__setup("psi=", setup_psi); + +/* Running averages - we need to be higher-res than loadavg */ +#define PSI_FREQ (2*HZ+1) /* 2 sec intervals */ +#define EXP_10s 1677 /* 1/exp(2s/10s) as fixed-point */ +#define EXP_60s 1981 /* 1/exp(2s/60s) */ +#define EXP_300s 2034 /* 1/exp(2s/300s) */ + +/* PSI trigger definitions */ +#define WINDOW_MAX_US 10000000 /* Max window size is 10s */ +#define UPDATES_PER_WINDOW 10 /* 10 updates per window */ + +/* Sampling frequency in nanoseconds */ +static u64 psi_period __read_mostly; + +/* System-level pressure and stall tracking */ +static DEFINE_PER_CPU(struct psi_group_cpu, system_group_pcpu); +struct psi_group psi_system = { + .pcpu = &system_group_pcpu, +}; + +static void psi_avgs_work(struct work_struct *work); + +static void poll_timer_fn(struct timer_list *t); + +static void group_init(struct psi_group *group) +{ + int cpu; + + group->enabled = true; + for_each_possible_cpu(cpu) + seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq); + group->avg_last_update = sched_clock(); + group->avg_next_update = group->avg_last_update + psi_period; + mutex_init(&group->avgs_lock); + + /* Init avg trigger-related members */ + INIT_LIST_HEAD(&group->avg_triggers); + memset(group->avg_nr_triggers, 0, sizeof(group->avg_nr_triggers)); + INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work); + + /* Init rtpoll trigger-related members */ + atomic_set(&group->rtpoll_scheduled, 0); + mutex_init(&group->rtpoll_trigger_lock); + INIT_LIST_HEAD(&group->rtpoll_triggers); + group->rtpoll_min_period = U32_MAX; + group->rtpoll_next_update = ULLONG_MAX; + init_waitqueue_head(&group->rtpoll_wait); + timer_setup(&group->rtpoll_timer, poll_timer_fn, 0); + rcu_assign_pointer(group->rtpoll_task, NULL); +} + +void __init psi_init(void) +{ + if (!psi_enable) { + static_branch_enable(&psi_disabled); + static_branch_disable(&psi_cgroups_enabled); + return; + } + + if (!cgroup_psi_enabled()) + static_branch_disable(&psi_cgroups_enabled); + + psi_period = jiffies_to_nsecs(PSI_FREQ); + group_init(&psi_system); +} + +static bool test_state(unsigned int *tasks, enum psi_states state, bool oncpu) +{ + switch (state) { + case PSI_IO_SOME: + return unlikely(tasks[NR_IOWAIT]); + case PSI_IO_FULL: + return unlikely(tasks[NR_IOWAIT] && !tasks[NR_RUNNING]); + case PSI_MEM_SOME: + return unlikely(tasks[NR_MEMSTALL]); + case PSI_MEM_FULL: + return unlikely(tasks[NR_MEMSTALL] && + tasks[NR_RUNNING] == tasks[NR_MEMSTALL_RUNNING]); + case PSI_CPU_SOME: + return unlikely(tasks[NR_RUNNING] > oncpu); + case PSI_CPU_FULL: + return unlikely(tasks[NR_RUNNING] && !oncpu); + case PSI_NONIDLE: + return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] || + tasks[NR_RUNNING]; + default: + return false; + } +} + +static void get_recent_times(struct psi_group *group, int cpu, + enum psi_aggregators aggregator, u32 *times, + u32 *pchanged_states) +{ + struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu); + int current_cpu = raw_smp_processor_id(); + unsigned int tasks[NR_PSI_TASK_COUNTS]; + u64 now, state_start; + enum psi_states s; + unsigned int seq; + u32 state_mask; + + *pchanged_states = 0; + + /* Snapshot a coherent view of the CPU state */ + do { + seq = read_seqcount_begin(&groupc->seq); + now = cpu_clock(cpu); + memcpy(times, groupc->times, sizeof(groupc->times)); + state_mask = groupc->state_mask; + state_start = groupc->state_start; + if (cpu == current_cpu) + memcpy(tasks, groupc->tasks, sizeof(groupc->tasks)); + } while (read_seqcount_retry(&groupc->seq, seq)); + + /* Calculate state time deltas against the previous snapshot */ + for (s = 0; s < NR_PSI_STATES; s++) { + u32 delta; + /* + * In addition to already concluded states, we also + * incorporate currently active states on the CPU, + * since states may last for many sampling periods. + * + * This way we keep our delta sampling buckets small + * (u32) and our reported pressure close to what's + * actually happening. + */ + if (state_mask & (1 << s)) + times[s] += now - state_start; + + delta = times[s] - groupc->times_prev[aggregator][s]; + groupc->times_prev[aggregator][s] = times[s]; + + times[s] = delta; + if (delta) + *pchanged_states |= (1 << s); + } + + /* + * When collect_percpu_times() from the avgs_work, we don't want to + * re-arm avgs_work when all CPUs are IDLE. But the current CPU running + * this avgs_work is never IDLE, cause avgs_work can't be shut off. + * So for the current CPU, we need to re-arm avgs_work only when + * (NR_RUNNING > 1 || NR_IOWAIT > 0 || NR_MEMSTALL > 0), for other CPUs + * we can just check PSI_NONIDLE delta. + */ + if (current_work() == &group->avgs_work.work) { + bool reschedule; + + if (cpu == current_cpu) + reschedule = tasks[NR_RUNNING] + + tasks[NR_IOWAIT] + + tasks[NR_MEMSTALL] > 1; + else + reschedule = *pchanged_states & (1 << PSI_NONIDLE); + + if (reschedule) + *pchanged_states |= PSI_STATE_RESCHEDULE; + } +} + +static void calc_avgs(unsigned long avg[3], int missed_periods, + u64 time, u64 period) +{ + unsigned long pct; + + /* Fill in zeroes for periods of no activity */ + if (missed_periods) { + avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods); + avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods); + avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods); + } + + /* Sample the most recent active period */ + pct = div_u64(time * 100, period); + pct *= FIXED_1; + avg[0] = calc_load(avg[0], EXP_10s, pct); + avg[1] = calc_load(avg[1], EXP_60s, pct); + avg[2] = calc_load(avg[2], EXP_300s, pct); +} + +static void collect_percpu_times(struct psi_group *group, + enum psi_aggregators aggregator, + u32 *pchanged_states) +{ + u64 deltas[NR_PSI_STATES - 1] = { 0, }; + unsigned long nonidle_total = 0; + u32 changed_states = 0; + int cpu; + int s; + + /* + * Collect the per-cpu time buckets and average them into a + * single time sample that is normalized to wallclock time. + * + * For averaging, each CPU is weighted by its non-idle time in + * the sampling period. This eliminates artifacts from uneven + * loading, or even entirely idle CPUs. + */ + for_each_possible_cpu(cpu) { + u32 times[NR_PSI_STATES]; + u32 nonidle; + u32 cpu_changed_states; + + get_recent_times(group, cpu, aggregator, times, + &cpu_changed_states); + changed_states |= cpu_changed_states; + + nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]); + nonidle_total += nonidle; + + for (s = 0; s < PSI_NONIDLE; s++) + deltas[s] += (u64)times[s] * nonidle; + } + + /* + * Integrate the sample into the running statistics that are + * reported to userspace: the cumulative stall times and the + * decaying averages. + * + * Pressure percentages are sampled at PSI_FREQ. We might be + * called more often when the user polls more frequently than + * that; we might be called less often when there is no task + * activity, thus no data, and clock ticks are sporadic. The + * below handles both. + */ + + /* total= */ + for (s = 0; s < NR_PSI_STATES - 1; s++) + group->total[aggregator][s] += + div_u64(deltas[s], max(nonidle_total, 1UL)); + + if (pchanged_states) + *pchanged_states = changed_states; +} + +/* Trigger tracking window manipulations */ +static void window_reset(struct psi_window *win, u64 now, u64 value, + u64 prev_growth) +{ + win->start_time = now; + win->start_value = value; + win->prev_growth = prev_growth; +} + +/* + * PSI growth tracking window update and growth calculation routine. + * + * This approximates a sliding tracking window by interpolating + * partially elapsed windows using historical growth data from the + * previous intervals. This minimizes memory requirements (by not storing + * all the intermediate values in the previous window) and simplifies + * the calculations. It works well because PSI signal changes only in + * positive direction and over relatively small window sizes the growth + * is close to linear. + */ +static u64 window_update(struct psi_window *win, u64 now, u64 value) +{ + u64 elapsed; + u64 growth; + + elapsed = now - win->start_time; + growth = value - win->start_value; + /* + * After each tracking window passes win->start_value and + * win->start_time get reset and win->prev_growth stores + * the average per-window growth of the previous window. + * win->prev_growth is then used to interpolate additional + * growth from the previous window assuming it was linear. + */ + if (elapsed > win->size) + window_reset(win, now, value, growth); + else { + u32 remaining; + + remaining = win->size - elapsed; + growth += div64_u64(win->prev_growth * remaining, win->size); + } + + return growth; +} + +static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total, + enum psi_aggregators aggregator) +{ + struct psi_trigger *t; + u64 *total = group->total[aggregator]; + struct list_head *triggers; + u64 *aggregator_total; + *update_total = false; + + if (aggregator == PSI_AVGS) { + triggers = &group->avg_triggers; + aggregator_total = group->avg_total; + } else { + triggers = &group->rtpoll_triggers; + aggregator_total = group->rtpoll_total; + } + + /* + * On subsequent updates, calculate growth deltas and let + * watchers know when their specified thresholds are exceeded. + */ + list_for_each_entry(t, triggers, node) { + u64 growth; + bool new_stall; + + new_stall = aggregator_total[t->state] != total[t->state]; + + /* Check for stall activity or a previous threshold breach */ + if (!new_stall && !t->pending_event) + continue; + /* + * Check for new stall activity, as well as deferred + * events that occurred in the last window after the + * trigger had already fired (we want to ratelimit + * events without dropping any). + */ + if (new_stall) { + /* + * Multiple triggers might be looking at the same state, + * remember to update group->polling_total[] once we've + * been through all of them. Also remember to extend the + * polling time if we see new stall activity. + */ + *update_total = true; + + /* Calculate growth since last update */ + growth = window_update(&t->win, now, total[t->state]); + if (!t->pending_event) { + if (growth < t->threshold) + continue; + + t->pending_event = true; + } + } + /* Limit event signaling to once per window */ + if (now < t->last_event_time + t->win.size) + continue; + + /* Generate an event */ + if (cmpxchg(&t->event, 0, 1) == 0) { + if (t->of) + kernfs_notify(t->of->kn); + else + wake_up_interruptible(&t->event_wait); + } + t->last_event_time = now; + /* Reset threshold breach flag once event got generated */ + t->pending_event = false; + } + + return now + group->rtpoll_min_period; +} + +static u64 update_averages(struct psi_group *group, u64 now) +{ + unsigned long missed_periods = 0; + u64 expires, period; + u64 avg_next_update; + int s; + + /* avgX= */ + expires = group->avg_next_update; + if (now - expires >= psi_period) + missed_periods = div_u64(now - expires, psi_period); + + /* + * The periodic clock tick can get delayed for various + * reasons, especially on loaded systems. To avoid clock + * drift, we schedule the clock in fixed psi_period intervals. + * But the deltas we sample out of the per-cpu buckets above + * are based on the actual time elapsing between clock ticks. + */ + avg_next_update = expires + ((1 + missed_periods) * psi_period); + period = now - (group->avg_last_update + (missed_periods * psi_period)); + group->avg_last_update = now; + + for (s = 0; s < NR_PSI_STATES - 1; s++) { + u32 sample; + + sample = group->total[PSI_AVGS][s] - group->avg_total[s]; + /* + * Due to the lockless sampling of the time buckets, + * recorded time deltas can slip into the next period, + * which under full pressure can result in samples in + * excess of the period length. + * + * We don't want to report non-sensical pressures in + * excess of 100%, nor do we want to drop such events + * on the floor. Instead we punt any overage into the + * future until pressure subsides. By doing this we + * don't underreport the occurring pressure curve, we + * just report it delayed by one period length. + * + * The error isn't cumulative. As soon as another + * delta slips from a period P to P+1, by definition + * it frees up its time T in P. + */ + if (sample > period) + sample = period; + group->avg_total[s] += sample; + calc_avgs(group->avg[s], missed_periods, sample, period); + } + + return avg_next_update; +} + +static void psi_avgs_work(struct work_struct *work) +{ + struct delayed_work *dwork; + struct psi_group *group; + u32 changed_states; + bool update_total; + u64 now; + + dwork = to_delayed_work(work); + group = container_of(dwork, struct psi_group, avgs_work); + + mutex_lock(&group->avgs_lock); + + now = sched_clock(); + + collect_percpu_times(group, PSI_AVGS, &changed_states); + /* + * If there is task activity, periodically fold the per-cpu + * times and feed samples into the running averages. If things + * are idle and there is no data to process, stop the clock. + * Once restarted, we'll catch up the running averages in one + * go - see calc_avgs() and missed_periods. + */ + if (now >= group->avg_next_update) { + update_triggers(group, now, &update_total, PSI_AVGS); + group->avg_next_update = update_averages(group, now); + } + + if (changed_states & PSI_STATE_RESCHEDULE) { + schedule_delayed_work(dwork, nsecs_to_jiffies( + group->avg_next_update - now) + 1); + } + + mutex_unlock(&group->avgs_lock); +} + +static void init_rtpoll_triggers(struct psi_group *group, u64 now) +{ + struct psi_trigger *t; + + list_for_each_entry(t, &group->rtpoll_triggers, node) + window_reset(&t->win, now, + group->total[PSI_POLL][t->state], 0); + memcpy(group->rtpoll_total, group->total[PSI_POLL], + sizeof(group->rtpoll_total)); + group->rtpoll_next_update = now + group->rtpoll_min_period; +} + +/* Schedule polling if it's not already scheduled or forced. */ +static void psi_schedule_rtpoll_work(struct psi_group *group, unsigned long delay, + bool force) +{ + struct task_struct *task; + + /* + * atomic_xchg should be called even when !force to provide a + * full memory barrier (see the comment inside psi_rtpoll_work). + */ + if (atomic_xchg(&group->rtpoll_scheduled, 1) && !force) + return; + + rcu_read_lock(); + + task = rcu_dereference(group->rtpoll_task); + /* + * kworker might be NULL in case psi_trigger_destroy races with + * psi_task_change (hotpath) which can't use locks + */ + if (likely(task)) + mod_timer(&group->rtpoll_timer, jiffies + delay); + else + atomic_set(&group->rtpoll_scheduled, 0); + + rcu_read_unlock(); +} + +static void psi_rtpoll_work(struct psi_group *group) +{ + bool force_reschedule = false; + u32 changed_states; + bool update_total; + u64 now; + + mutex_lock(&group->rtpoll_trigger_lock); + + now = sched_clock(); + + if (now > group->rtpoll_until) { + /* + * We are either about to start or might stop polling if no + * state change was recorded. Resetting poll_scheduled leaves + * a small window for psi_group_change to sneak in and schedule + * an immediate poll_work before we get to rescheduling. One + * potential extra wakeup at the end of the polling window + * should be negligible and polling_next_update still keeps + * updates correctly on schedule. + */ + atomic_set(&group->rtpoll_scheduled, 0); + /* + * A task change can race with the poll worker that is supposed to + * report on it. To avoid missing events, ensure ordering between + * poll_scheduled and the task state accesses, such that if the poll + * worker misses the state update, the task change is guaranteed to + * reschedule the poll worker: + * + * poll worker: + * atomic_set(poll_scheduled, 0) + * smp_mb() + * LOAD states + * + * task change: + * STORE states + * if atomic_xchg(poll_scheduled, 1) == 0: + * schedule poll worker + * + * The atomic_xchg() implies a full barrier. + */ + smp_mb(); + } else { + /* Polling window is not over, keep rescheduling */ + force_reschedule = true; + } + + + collect_percpu_times(group, PSI_POLL, &changed_states); + + if (changed_states & group->rtpoll_states) { + /* Initialize trigger windows when entering polling mode */ + if (now > group->rtpoll_until) + init_rtpoll_triggers(group, now); + + /* + * Keep the monitor active for at least the duration of the + * minimum tracking window as long as monitor states are + * changing. + */ + group->rtpoll_until = now + + group->rtpoll_min_period * UPDATES_PER_WINDOW; + } + + if (now > group->rtpoll_until) { + group->rtpoll_next_update = ULLONG_MAX; + goto out; + } + + if (now >= group->rtpoll_next_update) { + group->rtpoll_next_update = update_triggers(group, now, &update_total, PSI_POLL); + if (update_total) + memcpy(group->rtpoll_total, group->total[PSI_POLL], + sizeof(group->rtpoll_total)); + } + + psi_schedule_rtpoll_work(group, + nsecs_to_jiffies(group->rtpoll_next_update - now) + 1, + force_reschedule); + +out: + mutex_unlock(&group->rtpoll_trigger_lock); +} + +static int psi_rtpoll_worker(void *data) +{ + struct psi_group *group = (struct psi_group *)data; + + sched_set_fifo_low(current); + + while (true) { + wait_event_interruptible(group->rtpoll_wait, + atomic_cmpxchg(&group->rtpoll_wakeup, 1, 0) || + kthread_should_stop()); + if (kthread_should_stop()) + break; + + psi_rtpoll_work(group); + } + return 0; +} + +static void poll_timer_fn(struct timer_list *t) +{ + struct psi_group *group = from_timer(group, t, rtpoll_timer); + + atomic_set(&group->rtpoll_wakeup, 1); + wake_up_interruptible(&group->rtpoll_wait); +} + +static void record_times(struct psi_group_cpu *groupc, u64 now) +{ + u32 delta; + + delta = now - groupc->state_start; + groupc->state_start = now; + + if (groupc->state_mask & (1 << PSI_IO_SOME)) { + groupc->times[PSI_IO_SOME] += delta; + if (groupc->state_mask & (1 << PSI_IO_FULL)) + groupc->times[PSI_IO_FULL] += delta; + } + + if (groupc->state_mask & (1 << PSI_MEM_SOME)) { + groupc->times[PSI_MEM_SOME] += delta; + if (groupc->state_mask & (1 << PSI_MEM_FULL)) + groupc->times[PSI_MEM_FULL] += delta; + } + + if (groupc->state_mask & (1 << PSI_CPU_SOME)) { + groupc->times[PSI_CPU_SOME] += delta; + if (groupc->state_mask & (1 << PSI_CPU_FULL)) + groupc->times[PSI_CPU_FULL] += delta; + } + + if (groupc->state_mask & (1 << PSI_NONIDLE)) + groupc->times[PSI_NONIDLE] += delta; +} + +static void psi_group_change(struct psi_group *group, int cpu, + unsigned int clear, unsigned int set, u64 now, + bool wake_clock) +{ + struct psi_group_cpu *groupc; + unsigned int t, m; + enum psi_states s; + u32 state_mask; + + groupc = per_cpu_ptr(group->pcpu, cpu); + + /* + * First we update the task counts according to the state + * change requested through the @clear and @set bits. + * + * Then if the cgroup PSI stats accounting enabled, we + * assess the aggregate resource states this CPU's tasks + * have been in since the last change, and account any + * SOME and FULL time these may have resulted in. + */ + write_seqcount_begin(&groupc->seq); + + /* + * Start with TSK_ONCPU, which doesn't have a corresponding + * task count - it's just a boolean flag directly encoded in + * the state mask. Clear, set, or carry the current state if + * no changes are requested. + */ + if (unlikely(clear & TSK_ONCPU)) { + state_mask = 0; + clear &= ~TSK_ONCPU; + } else if (unlikely(set & TSK_ONCPU)) { + state_mask = PSI_ONCPU; + set &= ~TSK_ONCPU; + } else { + state_mask = groupc->state_mask & PSI_ONCPU; + } + + /* + * The rest of the state mask is calculated based on the task + * counts. Update those first, then construct the mask. + */ + for (t = 0, m = clear; m; m &= ~(1 << t), t++) { + if (!(m & (1 << t))) + continue; + if (groupc->tasks[t]) { + groupc->tasks[t]--; + } else if (!psi_bug) { + printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u %u] clear=%x set=%x\n", + cpu, t, groupc->tasks[0], + groupc->tasks[1], groupc->tasks[2], + groupc->tasks[3], clear, set); + psi_bug = 1; + } + } + + for (t = 0; set; set &= ~(1 << t), t++) + if (set & (1 << t)) + groupc->tasks[t]++; + + if (!group->enabled) { + /* + * On the first group change after disabling PSI, conclude + * the current state and flush its time. This is unlikely + * to matter to the user, but aggregation (get_recent_times) + * may have already incorporated the live state into times_prev; + * avoid a delta sample underflow when PSI is later re-enabled. + */ + if (unlikely(groupc->state_mask & (1 << PSI_NONIDLE))) + record_times(groupc, now); + + groupc->state_mask = state_mask; + + write_seqcount_end(&groupc->seq); + return; + } + + for (s = 0; s < NR_PSI_STATES; s++) { + if (test_state(groupc->tasks, s, state_mask & PSI_ONCPU)) + state_mask |= (1 << s); + } + + /* + * Since we care about lost potential, a memstall is FULL + * when there are no other working tasks, but also when + * the CPU is actively reclaiming and nothing productive + * could run even if it were runnable. So when the current + * task in a cgroup is in_memstall, the corresponding groupc + * on that cpu is in PSI_MEM_FULL state. + */ + if (unlikely((state_mask & PSI_ONCPU) && cpu_curr(cpu)->in_memstall)) + state_mask |= (1 << PSI_MEM_FULL); + + record_times(groupc, now); + + groupc->state_mask = state_mask; + + write_seqcount_end(&groupc->seq); + + if (state_mask & group->rtpoll_states) + psi_schedule_rtpoll_work(group, 1, false); + + if (wake_clock && !delayed_work_pending(&group->avgs_work)) + schedule_delayed_work(&group->avgs_work, PSI_FREQ); +} + +static inline struct psi_group *task_psi_group(struct task_struct *task) +{ +#ifdef CONFIG_CGROUPS + if (static_branch_likely(&psi_cgroups_enabled)) + return cgroup_psi(task_dfl_cgroup(task)); +#endif + return &psi_system; +} + +static void psi_flags_change(struct task_struct *task, int clear, int set) +{ + if (((task->psi_flags & set) || + (task->psi_flags & clear) != clear) && + !psi_bug) { + printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n", + task->pid, task->comm, task_cpu(task), + task->psi_flags, clear, set); + psi_bug = 1; + } + + task->psi_flags &= ~clear; + task->psi_flags |= set; +} + +void psi_task_change(struct task_struct *task, int clear, int set) +{ + int cpu = task_cpu(task); + struct psi_group *group; + u64 now; + + if (!task->pid) + return; + + psi_flags_change(task, clear, set); + + now = cpu_clock(cpu); + + group = task_psi_group(task); + do { + psi_group_change(group, cpu, clear, set, now, true); + } while ((group = group->parent)); +} + +void psi_task_switch(struct task_struct *prev, struct task_struct *next, + bool sleep) +{ + struct psi_group *group, *common = NULL; + int cpu = task_cpu(prev); + u64 now = cpu_clock(cpu); + + if (next->pid) { + psi_flags_change(next, 0, TSK_ONCPU); + /* + * Set TSK_ONCPU on @next's cgroups. If @next shares any + * ancestors with @prev, those will already have @prev's + * TSK_ONCPU bit set, and we can stop the iteration there. + */ + group = task_psi_group(next); + do { + if (per_cpu_ptr(group->pcpu, cpu)->state_mask & + PSI_ONCPU) { + common = group; + break; + } + + psi_group_change(group, cpu, 0, TSK_ONCPU, now, true); + } while ((group = group->parent)); + } + + if (prev->pid) { + int clear = TSK_ONCPU, set = 0; + bool wake_clock = true; + + /* + * When we're going to sleep, psi_dequeue() lets us + * handle TSK_RUNNING, TSK_MEMSTALL_RUNNING and + * TSK_IOWAIT here, where we can combine it with + * TSK_ONCPU and save walking common ancestors twice. + */ + if (sleep) { + clear |= TSK_RUNNING; + if (prev->in_memstall) + clear |= TSK_MEMSTALL_RUNNING; + if (prev->in_iowait) + set |= TSK_IOWAIT; + + /* + * Periodic aggregation shuts off if there is a period of no + * task changes, so we wake it back up if necessary. However, + * don't do this if the task change is the aggregation worker + * itself going to sleep, or we'll ping-pong forever. + */ + if (unlikely((prev->flags & PF_WQ_WORKER) && + wq_worker_last_func(prev) == psi_avgs_work)) + wake_clock = false; + } + + psi_flags_change(prev, clear, set); + + group = task_psi_group(prev); + do { + if (group == common) + break; + psi_group_change(group, cpu, clear, set, now, wake_clock); + } while ((group = group->parent)); + + /* + * TSK_ONCPU is handled up to the common ancestor. If there are + * any other differences between the two tasks (e.g. prev goes + * to sleep, or only one task is memstall), finish propagating + * those differences all the way up to the root. + */ + if ((prev->psi_flags ^ next->psi_flags) & ~TSK_ONCPU) { + clear &= ~TSK_ONCPU; + for (; group; group = group->parent) + psi_group_change(group, cpu, clear, set, now, wake_clock); + } + } +} + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING +void psi_account_irqtime(struct task_struct *task, u32 delta) +{ + int cpu = task_cpu(task); + struct psi_group *group; + struct psi_group_cpu *groupc; + u64 now; + + if (!task->pid) + return; + + now = cpu_clock(cpu); + + group = task_psi_group(task); + do { + if (!group->enabled) + continue; + + groupc = per_cpu_ptr(group->pcpu, cpu); + + write_seqcount_begin(&groupc->seq); + + record_times(groupc, now); + groupc->times[PSI_IRQ_FULL] += delta; + + write_seqcount_end(&groupc->seq); + + if (group->rtpoll_states & (1 << PSI_IRQ_FULL)) + psi_schedule_rtpoll_work(group, 1, false); + } while ((group = group->parent)); +} +#endif + +/** + * psi_memstall_enter - mark the beginning of a memory stall section + * @flags: flags to handle nested sections + * + * Marks the calling task as being stalled due to a lack of memory, + * such as waiting for a refault or performing reclaim. + */ +void psi_memstall_enter(unsigned long *flags) +{ + struct rq_flags rf; + struct rq *rq; + + if (static_branch_likely(&psi_disabled)) + return; + + *flags = current->in_memstall; + if (*flags) + return; + /* + * in_memstall setting & accounting needs to be atomic wrt + * changes to the task's scheduling state, otherwise we can + * race with CPU migration. + */ + rq = this_rq_lock_irq(&rf); + + current->in_memstall = 1; + psi_task_change(current, 0, TSK_MEMSTALL | TSK_MEMSTALL_RUNNING); + + rq_unlock_irq(rq, &rf); +} +EXPORT_SYMBOL_GPL(psi_memstall_enter); + +/** + * psi_memstall_leave - mark the end of an memory stall section + * @flags: flags to handle nested memdelay sections + * + * Marks the calling task as no longer stalled due to lack of memory. + */ +void psi_memstall_leave(unsigned long *flags) +{ + struct rq_flags rf; + struct rq *rq; + + if (static_branch_likely(&psi_disabled)) + return; + + if (*flags) + return; + /* + * in_memstall clearing & accounting needs to be atomic wrt + * changes to the task's scheduling state, otherwise we could + * race with CPU migration. + */ + rq = this_rq_lock_irq(&rf); + + current->in_memstall = 0; + psi_task_change(current, TSK_MEMSTALL | TSK_MEMSTALL_RUNNING, 0); + + rq_unlock_irq(rq, &rf); +} +EXPORT_SYMBOL_GPL(psi_memstall_leave); + +#ifdef CONFIG_CGROUPS +int psi_cgroup_alloc(struct cgroup *cgroup) +{ + if (!static_branch_likely(&psi_cgroups_enabled)) + return 0; + + cgroup->psi = kzalloc(sizeof(struct psi_group), GFP_KERNEL); + if (!cgroup->psi) + return -ENOMEM; + + cgroup->psi->pcpu = alloc_percpu(struct psi_group_cpu); + if (!cgroup->psi->pcpu) { + kfree(cgroup->psi); + return -ENOMEM; + } + group_init(cgroup->psi); + cgroup->psi->parent = cgroup_psi(cgroup_parent(cgroup)); + return 0; +} + +void psi_cgroup_free(struct cgroup *cgroup) +{ + if (!static_branch_likely(&psi_cgroups_enabled)) + return; + + cancel_delayed_work_sync(&cgroup->psi->avgs_work); + free_percpu(cgroup->psi->pcpu); + /* All triggers must be removed by now */ + WARN_ONCE(cgroup->psi->rtpoll_states, "psi: trigger leak\n"); + kfree(cgroup->psi); +} + +/** + * cgroup_move_task - move task to a different cgroup + * @task: the task + * @to: the target css_set + * + * Move task to a new cgroup and safely migrate its associated stall + * state between the different groups. + * + * This function acquires the task's rq lock to lock out concurrent + * changes to the task's scheduling state and - in case the task is + * running - concurrent changes to its stall state. + */ +void cgroup_move_task(struct task_struct *task, struct css_set *to) +{ + unsigned int task_flags; + struct rq_flags rf; + struct rq *rq; + + if (!static_branch_likely(&psi_cgroups_enabled)) { + /* + * Lame to do this here, but the scheduler cannot be locked + * from the outside, so we move cgroups from inside sched/. + */ + rcu_assign_pointer(task->cgroups, to); + return; + } + + rq = task_rq_lock(task, &rf); + + /* + * We may race with schedule() dropping the rq lock between + * deactivating prev and switching to next. Because the psi + * updates from the deactivation are deferred to the switch + * callback to save cgroup tree updates, the task's scheduling + * state here is not coherent with its psi state: + * + * schedule() cgroup_move_task() + * rq_lock() + * deactivate_task() + * p->on_rq = 0 + * psi_dequeue() // defers TSK_RUNNING & TSK_IOWAIT updates + * pick_next_task() + * rq_unlock() + * rq_lock() + * psi_task_change() // old cgroup + * task->cgroups = to + * psi_task_change() // new cgroup + * rq_unlock() + * rq_lock() + * psi_sched_switch() // does deferred updates in new cgroup + * + * Don't rely on the scheduling state. Use psi_flags instead. + */ + task_flags = task->psi_flags; + + if (task_flags) + psi_task_change(task, task_flags, 0); + + /* See comment above */ + rcu_assign_pointer(task->cgroups, to); + + if (task_flags) + psi_task_change(task, 0, task_flags); + + task_rq_unlock(rq, task, &rf); +} + +void psi_cgroup_restart(struct psi_group *group) +{ + int cpu; + + /* + * After we disable psi_group->enabled, we don't actually + * stop percpu tasks accounting in each psi_group_cpu, + * instead only stop test_state() loop, record_times() + * and averaging worker, see psi_group_change() for details. + * + * When disable cgroup PSI, this function has nothing to sync + * since cgroup pressure files are hidden and percpu psi_group_cpu + * would see !psi_group->enabled and only do task accounting. + * + * When re-enable cgroup PSI, this function use psi_group_change() + * to get correct state mask from test_state() loop on tasks[], + * and restart groupc->state_start from now, use .clear = .set = 0 + * here since no task status really changed. + */ + if (!group->enabled) + return; + + for_each_possible_cpu(cpu) { + struct rq *rq = cpu_rq(cpu); + struct rq_flags rf; + u64 now; + + rq_lock_irq(rq, &rf); + now = cpu_clock(cpu); + psi_group_change(group, cpu, 0, 0, now, true); + rq_unlock_irq(rq, &rf); + } +} +#endif /* CONFIG_CGROUPS */ + +int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res) +{ + bool only_full = false; + int full; + u64 now; + + if (static_branch_likely(&psi_disabled)) + return -EOPNOTSUPP; + + /* Update averages before reporting them */ + mutex_lock(&group->avgs_lock); + now = sched_clock(); + collect_percpu_times(group, PSI_AVGS, NULL); + if (now >= group->avg_next_update) + group->avg_next_update = update_averages(group, now); + mutex_unlock(&group->avgs_lock); + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + only_full = res == PSI_IRQ; +#endif + + for (full = 0; full < 2 - only_full; full++) { + unsigned long avg[3] = { 0, }; + u64 total = 0; + int w; + + /* CPU FULL is undefined at the system level */ + if (!(group == &psi_system && res == PSI_CPU && full)) { + for (w = 0; w < 3; w++) + avg[w] = group->avg[res * 2 + full][w]; + total = div_u64(group->total[PSI_AVGS][res * 2 + full], + NSEC_PER_USEC); + } + + seq_printf(m, "%s avg10=%lu.%02lu avg60=%lu.%02lu avg300=%lu.%02lu total=%llu\n", + full || only_full ? "full" : "some", + LOAD_INT(avg[0]), LOAD_FRAC(avg[0]), + LOAD_INT(avg[1]), LOAD_FRAC(avg[1]), + LOAD_INT(avg[2]), LOAD_FRAC(avg[2]), + total); + } + + return 0; +} + +struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf, + enum psi_res res, struct file *file, + struct kernfs_open_file *of) +{ + struct psi_trigger *t; + enum psi_states state; + u32 threshold_us; + bool privileged; + u32 window_us; + + if (static_branch_likely(&psi_disabled)) + return ERR_PTR(-EOPNOTSUPP); + + /* + * Checking the privilege here on file->f_cred implies that a privileged user + * could open the file and delegate the write to an unprivileged one. + */ + privileged = cap_raised(file->f_cred->cap_effective, CAP_SYS_RESOURCE); + + if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2) + state = PSI_IO_SOME + res * 2; + else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2) + state = PSI_IO_FULL + res * 2; + else + return ERR_PTR(-EINVAL); + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + if (res == PSI_IRQ && --state != PSI_IRQ_FULL) + return ERR_PTR(-EINVAL); +#endif + + if (state >= PSI_NONIDLE) + return ERR_PTR(-EINVAL); + + if (window_us == 0 || window_us > WINDOW_MAX_US) + return ERR_PTR(-EINVAL); + + /* + * Unprivileged users can only use 2s windows so that averages aggregation + * work is used, and no RT threads need to be spawned. + */ + if (!privileged && window_us % 2000000) + return ERR_PTR(-EINVAL); + + /* Check threshold */ + if (threshold_us == 0 || threshold_us > window_us) + return ERR_PTR(-EINVAL); + + t = kmalloc(sizeof(*t), GFP_KERNEL); + if (!t) + return ERR_PTR(-ENOMEM); + + t->group = group; + t->state = state; + t->threshold = threshold_us * NSEC_PER_USEC; + t->win.size = window_us * NSEC_PER_USEC; + window_reset(&t->win, sched_clock(), + group->total[PSI_POLL][t->state], 0); + + t->event = 0; + t->last_event_time = 0; + t->of = of; + if (!of) + init_waitqueue_head(&t->event_wait); + t->pending_event = false; + t->aggregator = privileged ? PSI_POLL : PSI_AVGS; + + if (privileged) { + mutex_lock(&group->rtpoll_trigger_lock); + + if (!rcu_access_pointer(group->rtpoll_task)) { + struct task_struct *task; + + task = kthread_create(psi_rtpoll_worker, group, "psimon"); + if (IS_ERR(task)) { + kfree(t); + mutex_unlock(&group->rtpoll_trigger_lock); + return ERR_CAST(task); + } + atomic_set(&group->rtpoll_wakeup, 0); + wake_up_process(task); + rcu_assign_pointer(group->rtpoll_task, task); + } + + list_add(&t->node, &group->rtpoll_triggers); + group->rtpoll_min_period = min(group->rtpoll_min_period, + div_u64(t->win.size, UPDATES_PER_WINDOW)); + group->rtpoll_nr_triggers[t->state]++; + group->rtpoll_states |= (1 << t->state); + + mutex_unlock(&group->rtpoll_trigger_lock); + } else { + mutex_lock(&group->avgs_lock); + + list_add(&t->node, &group->avg_triggers); + group->avg_nr_triggers[t->state]++; + + mutex_unlock(&group->avgs_lock); + } + return t; +} + +void psi_trigger_destroy(struct psi_trigger *t) +{ + struct psi_group *group; + struct task_struct *task_to_destroy = NULL; + + /* + * We do not check psi_disabled since it might have been disabled after + * the trigger got created. + */ + if (!t) + return; + + group = t->group; + /* + * Wakeup waiters to stop polling and clear the queue to prevent it from + * being accessed later. Can happen if cgroup is deleted from under a + * polling process. + */ + if (t->of) + kernfs_notify(t->of->kn); + else + wake_up_interruptible(&t->event_wait); + + if (t->aggregator == PSI_AVGS) { + mutex_lock(&group->avgs_lock); + if (!list_empty(&t->node)) { + list_del(&t->node); + group->avg_nr_triggers[t->state]--; + } + mutex_unlock(&group->avgs_lock); + } else { + mutex_lock(&group->rtpoll_trigger_lock); + if (!list_empty(&t->node)) { + struct psi_trigger *tmp; + u64 period = ULLONG_MAX; + + list_del(&t->node); + group->rtpoll_nr_triggers[t->state]--; + if (!group->rtpoll_nr_triggers[t->state]) + group->rtpoll_states &= ~(1 << t->state); + /* + * Reset min update period for the remaining triggers + * iff the destroying trigger had the min window size. + */ + if (group->rtpoll_min_period == div_u64(t->win.size, UPDATES_PER_WINDOW)) { + list_for_each_entry(tmp, &group->rtpoll_triggers, node) + period = min(period, div_u64(tmp->win.size, + UPDATES_PER_WINDOW)); + group->rtpoll_min_period = period; + } + /* Destroy rtpoll_task when the last trigger is destroyed */ + if (group->rtpoll_states == 0) { + group->rtpoll_until = 0; + task_to_destroy = rcu_dereference_protected( + group->rtpoll_task, + lockdep_is_held(&group->rtpoll_trigger_lock)); + rcu_assign_pointer(group->rtpoll_task, NULL); + del_timer(&group->rtpoll_timer); + } + } + mutex_unlock(&group->rtpoll_trigger_lock); + } + + /* + * Wait for psi_schedule_rtpoll_work RCU to complete its read-side + * critical section before destroying the trigger and optionally the + * rtpoll_task. + */ + synchronize_rcu(); + /* + * Stop kthread 'psimon' after releasing rtpoll_trigger_lock to prevent + * a deadlock while waiting for psi_rtpoll_work to acquire + * rtpoll_trigger_lock + */ + if (task_to_destroy) { + /* + * After the RCU grace period has expired, the worker + * can no longer be found through group->rtpoll_task. + */ + kthread_stop(task_to_destroy); + atomic_set(&group->rtpoll_scheduled, 0); + } + kfree(t); +} + +__poll_t psi_trigger_poll(void **trigger_ptr, + struct file *file, poll_table *wait) +{ + __poll_t ret = DEFAULT_POLLMASK; + struct psi_trigger *t; + + if (static_branch_likely(&psi_disabled)) + return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI; + + t = smp_load_acquire(trigger_ptr); + if (!t) + return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI; + + if (t->of) + kernfs_generic_poll(t->of, wait); + else + poll_wait(file, &t->event_wait, wait); + + if (cmpxchg(&t->event, 1, 0) == 1) + ret |= EPOLLPRI; + + return ret; +} + +#ifdef CONFIG_PROC_FS +static int psi_io_show(struct seq_file *m, void *v) +{ + return psi_show(m, &psi_system, PSI_IO); +} + +static int psi_memory_show(struct seq_file *m, void *v) +{ + return psi_show(m, &psi_system, PSI_MEM); +} + +static int psi_cpu_show(struct seq_file *m, void *v) +{ + return psi_show(m, &psi_system, PSI_CPU); +} + +static int psi_io_open(struct inode *inode, struct file *file) +{ + return single_open(file, psi_io_show, NULL); +} + +static int psi_memory_open(struct inode *inode, struct file *file) +{ + return single_open(file, psi_memory_show, NULL); +} + +static int psi_cpu_open(struct inode *inode, struct file *file) +{ + return single_open(file, psi_cpu_show, NULL); +} + +static ssize_t psi_write(struct file *file, const char __user *user_buf, + size_t nbytes, enum psi_res res) +{ + char buf[32]; + size_t buf_size; + struct seq_file *seq; + struct psi_trigger *new; + + if (static_branch_likely(&psi_disabled)) + return -EOPNOTSUPP; + + if (!nbytes) + return -EINVAL; + + buf_size = min(nbytes, sizeof(buf)); + if (copy_from_user(buf, user_buf, buf_size)) + return -EFAULT; + + buf[buf_size - 1] = '\0'; + + seq = file->private_data; + + /* Take seq->lock to protect seq->private from concurrent writes */ + mutex_lock(&seq->lock); + + /* Allow only one trigger per file descriptor */ + if (seq->private) { + mutex_unlock(&seq->lock); + return -EBUSY; + } + + new = psi_trigger_create(&psi_system, buf, res, file, NULL); + if (IS_ERR(new)) { + mutex_unlock(&seq->lock); + return PTR_ERR(new); + } + + smp_store_release(&seq->private, new); + mutex_unlock(&seq->lock); + + return nbytes; +} + +static ssize_t psi_io_write(struct file *file, const char __user *user_buf, + size_t nbytes, loff_t *ppos) +{ + return psi_write(file, user_buf, nbytes, PSI_IO); +} + +static ssize_t psi_memory_write(struct file *file, const char __user *user_buf, + size_t nbytes, loff_t *ppos) +{ + return psi_write(file, user_buf, nbytes, PSI_MEM); +} + +static ssize_t psi_cpu_write(struct file *file, const char __user *user_buf, + size_t nbytes, loff_t *ppos) +{ + return psi_write(file, user_buf, nbytes, PSI_CPU); +} + +static __poll_t psi_fop_poll(struct file *file, poll_table *wait) +{ + struct seq_file *seq = file->private_data; + + return psi_trigger_poll(&seq->private, file, wait); +} + +static int psi_fop_release(struct inode *inode, struct file *file) +{ + struct seq_file *seq = file->private_data; + + psi_trigger_destroy(seq->private); + return single_release(inode, file); +} + +static const struct proc_ops psi_io_proc_ops = { + .proc_open = psi_io_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_write = psi_io_write, + .proc_poll = psi_fop_poll, + .proc_release = psi_fop_release, +}; + +static const struct proc_ops psi_memory_proc_ops = { + .proc_open = psi_memory_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_write = psi_memory_write, + .proc_poll = psi_fop_poll, + .proc_release = psi_fop_release, +}; + +static const struct proc_ops psi_cpu_proc_ops = { + .proc_open = psi_cpu_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_write = psi_cpu_write, + .proc_poll = psi_fop_poll, + .proc_release = psi_fop_release, +}; + +#ifdef CONFIG_IRQ_TIME_ACCOUNTING +static int psi_irq_show(struct seq_file *m, void *v) +{ + return psi_show(m, &psi_system, PSI_IRQ); +} + +static int psi_irq_open(struct inode *inode, struct file *file) +{ + return single_open(file, psi_irq_show, NULL); +} + +static ssize_t psi_irq_write(struct file *file, const char __user *user_buf, + size_t nbytes, loff_t *ppos) +{ + return psi_write(file, user_buf, nbytes, PSI_IRQ); +} + +static const struct proc_ops psi_irq_proc_ops = { + .proc_open = psi_irq_open, + .proc_read = seq_read, + .proc_lseek = seq_lseek, + .proc_write = psi_irq_write, + .proc_poll = psi_fop_poll, + .proc_release = psi_fop_release, +}; +#endif + +static int __init psi_proc_init(void) +{ + if (psi_enable) { + proc_mkdir("pressure", NULL); + proc_create("pressure/io", 0666, NULL, &psi_io_proc_ops); + proc_create("pressure/memory", 0666, NULL, &psi_memory_proc_ops); + proc_create("pressure/cpu", 0666, NULL, &psi_cpu_proc_ops); +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + proc_create("pressure/irq", 0666, NULL, &psi_irq_proc_ops); +#endif + } + return 0; +} +module_init(psi_proc_init); + +#endif /* CONFIG_PROC_FS */ |