// SPDX-License-Identifier: GPL-2.0
/*
* Pressure stall information for CPU, memory and IO
*
* Copyright (c) 2018 Facebook, Inc.
* Author: Johannes Weiner <[email protected]>
*
* Polling support by Suren Baghdasaryan <[email protected]>
* 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 on-CPU 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 wall clock 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 u32 test_states(unsigned int *tasks, u32 state_mask)
{
const bool oncpu = state_mask & PSI_ONCPU;
if (tasks[NR_IOWAIT]) {
state_mask |= BIT(PSI_IO_SOME);
if (!tasks[NR_RUNNING])
state_mask |= BIT(PSI_IO_FULL);
}
if (tasks[NR_MEMSTALL]) {
state_mask |= BIT(PSI_MEM_SOME);
if (tasks[NR_RUNNING] == tasks[NR_MEMSTALL_RUNNING])
state_mask |= BIT(PSI_MEM_FULL);
}
if (tasks[NR_RUNNING] > oncpu)
state_mask |= BIT(PSI_CPU_SOME);
if (tasks[NR_RUNNING] && !oncpu)
state_mask |= BIT(PSI_CPU_FULL);
if (tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] || tasks[NR_RUNNING])
state_mask |= BIT(PSI_NONIDLE);
return state_mask;
}
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 wall clock 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 void update_triggers(struct psi_group *group, u64 now,
enum psi_aggregators aggregator)
{
struct psi_trigger *t;
u64 *total = group->total[aggregator];
struct list_head *triggers;
u64 *aggregator_total;
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) {
/* 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;
}
}
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;
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, 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 rtpolling 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;
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 rtpolling if no
* state change was recorded. Resetting rtpoll_scheduled leaves
* a small window for psi_group_change to sneak in and schedule
* an immediate rtpoll_work before we get to rescheduling. One
* potential extra wakeup at the end of the rtpolling window
* should be negligible and rtpoll_next_update still keeps
* updates correctly on schedule.
*/
atomic_set(&group->rtpoll_scheduled, 0);
/*
* A task change can race with the rtpoll worker that is supposed to
* report on it. To avoid missing events, ensure ordering between
* rtpoll_scheduled and the task state accesses, such that if the
* rtpoll worker misses the state update, the task change is
* guaranteed to reschedule the rtpoll worker:
*
* rtpoll worker:
* atomic_set(rtpoll_scheduled, 0)
* smp_mb()
* LOAD states
*
* task change:
* STORE states
* if atomic_xchg(rtpoll_scheduled, 1) == 0:
* schedule rtpoll worker
*
* The atomic_xchg() implies a full barrier.
*/
smp_mb();
} else {
/* The rtpolling 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 rtpolling 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) {
if (changed_states & group->rtpoll_states) {
update_triggers(group, now, PSI_POLL);
memcpy(group->rtpoll_total, group->total[PSI_POLL],
sizeof(group->rtpoll_total));
}
group->rtpoll_next_update = now + group->rtpoll_min_period;
}
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,
bool wake_clock)
{
struct psi_group_cpu *groupc;
unsigned int t, m;
u32 state_mask;
u64 now;
lockdep_assert_rq_held(cpu_rq(cpu));
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);
now = cpu_clock(cpu);
/*
* 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;
}
state_mask = test_states(groupc->tasks, state_mask);
/*
* 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;
if (!task->pid)
return;
psi_flags_change(task, clear, set);
group = task_psi_group(task);
do {
psi_group_change(group, cpu, clear, set, 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);
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, 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, 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, wake_clock);
}
}
}
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
void psi_account_irqtime(struct rq *rq, struct task_struct *curr, struct task_struct *prev)
{
int cpu = task_cpu(curr);
struct psi_group *group;
struct psi_group_cpu *groupc;
s64 delta;
u64 irq;
if (static_branch_likely(&psi_disabled))
return;
if (!curr->pid)
return;
lockdep_assert_rq_held(rq);
group = task_psi_group(curr);
if (prev && task_psi_group(prev) == group)
return;
irq = irq_time_read(cpu);
delta = (s64)(irq - rq->psi_irq_time);
if (delta < 0)
return;
rq->psi_irq_time = irq;
do {
u64 now;
if (!group->enabled)
continue;
groupc = per_cpu_ptr(group->pcpu, cpu);
write_seqcount_begin(&groupc->seq);
now = cpu_clock(cpu);
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_states() 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_states() 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;
rq_lock_irq(rq, &rf);
psi_group_change(group, cpu, 0, 0, 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 */
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