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Commit 7c521739 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Patrick Daly
Browse files

psi: split update_stats into parts 



Split update_stats into collect_percpu_times and update_averages for
collect_percpu_times to be reused later inside psi monitor.

Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Change-Id: I3b9b571bd8bb9264f077a69ba6cabf23c36a4fb7
Patch-mainline: linux-mm @ 03/19/2019, 23:56
Signed-off-by: default avatarPatrick Daly <pdaly@codeaurora.org>
parent 52514355

kernel/sched/psi.c

+34 −23
Original line number Diff line number Diff line
@@ -269,17 +269,13 @@ static void calc_avgs(unsigned long avg[3], int missed_periods, 
	avg[2] = calc_load(avg[2], EXP_300s, pct);

}



static bool update_stats(struct psi_group *group)

static bool collect_percpu_times(struct psi_group *group)

{

	u64 deltas[NR_PSI_STATES - 1] = { 0, };

	unsigned long missed_periods = 0;

	unsigned long nonidle_total = 0;

	u64 now, expires, period;

	int cpu;

	int s;



	mutex_lock(&group->avgs_lock);



	/*

	 * Collect the per-cpu time buckets and average them into a

	 * single time sample that is normalized to wallclock time.
@@ -317,11 +313,18 @@ static bool update_stats(struct psi_group *group) 
	for (s = 0; s < NR_PSI_STATES - 1; s++)

		group->total[s] += div_u64(deltas[s], max(nonidle_total, 1UL));



	return nonidle_total;

}



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= */

	now = sched_clock();

	expires = group->avg_next_update;

	if (now < expires)

		goto out;

	if (now - expires >= psi_period)

		missed_periods = div_u64(now - expires, psi_period);
@@ -332,7 +335,7 @@ static bool update_stats(struct psi_group *group) 
	 * But the deltas we sample out of the per-cpu buckets above

	 * are based on the actual time elapsing between clock ticks.

	 */

	group->avg_next_update = expires + ((1 + missed_periods) * psi_period);

	avg_next_update = expires + ((1 + missed_periods) * psi_period);

	period = now - (group->avg_last_update + (missed_periods * psi_period));

	group->avg_last_update = now;
@@ -362,9 +365,8 @@ static bool update_stats(struct psi_group *group) 
		group->avg_total[s] += sample;

		calc_avgs(group->avg[s], missed_periods, sample, period);

	}

out:

	mutex_unlock(&group->avgs_lock);

	return nonidle_total;



	return avg_next_update;

}



static void psi_avgs_work(struct work_struct *work)
@@ -372,10 +374,16 @@ static void psi_avgs_work(struct work_struct *work) 
	struct delayed_work *dwork;

	struct psi_group *group;

	bool nonidle;

	u64 now;



	dwork = to_delayed_work(work);

	group = container_of(dwork, struct psi_group, avgs_work);



	mutex_lock(&group->avgs_lock);



	now = sched_clock();



	nonidle = collect_percpu_times(group);

	/*

	 * If there is task activity, periodically fold the per-cpu

	 * times and feed samples into the running averages. If things
@@ -383,19 +391,15 @@ static void psi_avgs_work(struct work_struct *work) 
	 * Once restarted, we'll catch up the running averages in one

	 * go - see calc_avgs() and missed_periods.

	 */



	nonidle = update_stats(group);

	if (now >= group->avg_next_update)

		group->avg_next_update = update_averages(group, now);



	if (nonidle) {

		unsigned long delay = 0;

		u64 now;



		now = sched_clock();

		if (group->avg_next_update > now)

			delay = nsecs_to_jiffies(

					group->avg_next_update - now) + 1;

		schedule_delayed_work(dwork, delay);

		schedule_delayed_work(dwork, nsecs_to_jiffies(

				group->avg_next_update - now) + 1);

	}



	mutex_unlock(&group->avgs_lock);

}



static void record_times(struct psi_group_cpu *groupc, int cpu,
@@ -707,11 +711,18 @@ void cgroup_move_task(struct task_struct *task, struct css_set *to) 
int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)

{

	int full;

	u64 now;



	if (static_branch_likely(&psi_disabled))

		return -EOPNOTSUPP;



	update_stats(group);

	/* Update averages before reporting them */

	mutex_lock(&group->avgs_lock);

	now = sched_clock();

	collect_percpu_times(group);

	if (now >= group->avg_next_update)

		group->avg_next_update = update_averages(group, now);

	mutex_unlock(&group->avgs_lock);



	for (full = 0; full < 2 - (res == PSI_CPU); full++) {

		unsigned long avg[3];