Commit 333f3017 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Linus Torvalds
Browse files

psi: track changed states 

Introduce changed_states parameter into collect_percpu_times to track
the states changed since the last update.

This will be needed to detect whether polled states activated in the
monitor patch.

Link: http://lkml.kernel.org/r/20190319235619.260832-6-surenb@google.com


Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7fc70a39

kernel/sched/psi.c

+18 −6
Original line number Diff line number Diff line
@@ -210,7 +210,8 @@ static bool test_state(unsigned int *tasks, enum psi_states state) 
	}

}



static void get_recent_times(struct psi_group *group, int cpu, u32 *times)

static void get_recent_times(struct psi_group *group, int cpu, u32 *times,

			     u32 *pchanged_states)

{

	struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);

	u64 now, state_start;
@@ -218,6 +219,8 @@ static void get_recent_times(struct psi_group *group, int cpu, u32 *times) 
	unsigned int seq;

	u32 state_mask;



	*pchanged_states = 0;



	/* Snapshot a coherent view of the CPU state */

	do {

		seq = read_seqcount_begin(&groupc->seq);
@@ -246,6 +249,8 @@ static void get_recent_times(struct psi_group *group, int cpu, u32 *times) 
		groupc->times_prev[s] = times[s];



		times[s] = delta;

		if (delta)

			*pchanged_states |= (1 << s);

	}

}
@@ -269,10 +274,11 @@ static void calc_avgs(unsigned long avg[3], int missed_periods, 
	avg[2] = calc_load(avg[2], EXP_300s, pct);

}



static bool collect_percpu_times(struct psi_group *group)

static void collect_percpu_times(struct psi_group *group, u32 *pchanged_states)

{

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

	unsigned long nonidle_total = 0;

	u32 changed_states = 0;

	int cpu;

	int s;
@@ -287,8 +293,11 @@ static bool collect_percpu_times(struct psi_group *group) 
	for_each_possible_cpu(cpu) {

		u32 times[NR_PSI_STATES];

		u32 nonidle;

		u32 cpu_changed_states;



		get_recent_times(group, cpu, times);

		get_recent_times(group, cpu, times,

				&cpu_changed_states);

		changed_states |= cpu_changed_states;



		nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]);

		nonidle_total += nonidle;
@@ -313,7 +322,8 @@ static bool collect_percpu_times(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;

	if (pchanged_states)

		*pchanged_states = changed_states;

}



static u64 update_averages(struct psi_group *group, u64 now)
@@ -373,6 +383,7 @@ static void psi_avgs_work(struct work_struct *work) 
{

	struct delayed_work *dwork;

	struct psi_group *group;

	u32 changed_states;

	bool nonidle;

	u64 now;
@@ -383,7 +394,8 @@ static void psi_avgs_work(struct work_struct *work) 


	now = sched_clock();



	nonidle = collect_percpu_times(group);

	collect_percpu_times(group, &changed_states);

	nonidle = changed_states & (1 << PSI_NONIDLE);

	/*

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

	 * times and feed samples into the running averages. If things
@@ -719,7 +731,7 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res) 
	/* Update averages before reporting them */

	mutex_lock(&group->avgs_lock);

	now = sched_clock();

	collect_percpu_times(group);

	collect_percpu_times(group, NULL);

	if (now >= group->avg_next_update)

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

	mutex_unlock(&group->avgs_lock);

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