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Commit 13962234 authored by Yuyang Du's avatar Yuyang Du Committed by Ingo Molnar
Browse files

sched/fair: Provide runnable_load_avg back to cfs_rq 



The cfs_rq's load_avg is composed of runnable_load_avg and blocked_load_avg.
Before this series, sometimes the runnable_load_avg is used, and sometimes
the load_avg is used. Completely replacing all uses of runnable_load_avg
with load_avg may be too big a leap, i.e., the blocked_load_avg is concerned
to result in overrated load. Therefore, we get runnable_load_avg back.

The new cfs_rq's runnable_load_avg is improved to be updated with all of the
runnable sched_eneities at the same time, so the one sched_entity updated and
the others stale problem is solved.

Signed-off-by: default avatarYuyang Du <yuyang.du@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-7-git-send-email-yuyang.du@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 12695578

kernel/sched/debug.c

+2 −0
Original line number Diff line number Diff line
@@ -207,6 +207,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 
#ifdef CONFIG_SMP

	SEQ_printf(m, "  .%-30s: %lu\n", "load_avg",

			cfs_rq->avg.load_avg);

	SEQ_printf(m, "  .%-30s: %lu\n", "runnable_load_avg",

			cfs_rq->runnable_load_avg);

	SEQ_printf(m, "  .%-30s: %lu\n", "util_avg",

			cfs_rq->avg.util_avg);

	SEQ_printf(m, "  .%-30s: %ld\n", "removed_load_avg",

kernel/sched/fair.c

+45 −10
Original line number Diff line number Diff line
@@ -2542,7 +2542,7 @@ static u32 __compute_runnable_contrib(u64 n) 
 */

static __always_inline int

__update_load_avg(u64 now, int cpu, struct sched_avg *sa,

		  unsigned long weight, int running)

		  unsigned long weight, int running, struct cfs_rq *cfs_rq)

{

	u64 delta, periods;

	u32 contrib;
@@ -2582,8 +2582,11 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa, 
		 * period and accrue it.

		 */

		delta_w = 1024 - delta_w;

		if (weight)

		if (weight) {

			sa->load_sum += weight * delta_w;

			if (cfs_rq)

				cfs_rq->runnable_load_sum += weight * delta_w;

		}

		if (running)

			sa->util_sum += delta_w * scale_freq >> SCHED_CAPACITY_SHIFT;
@@ -2594,19 +2597,29 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa, 
		delta %= 1024;



		sa->load_sum = decay_load(sa->load_sum, periods + 1);

		if (cfs_rq) {

			cfs_rq->runnable_load_sum =

				decay_load(cfs_rq->runnable_load_sum, periods + 1);

		}

		sa->util_sum = decay_load((u64)(sa->util_sum), periods + 1);



		/* Efficiently calculate \sum (1..n_period) 1024*y^i */

		contrib = __compute_runnable_contrib(periods);

		if (weight)

		if (weight) {

			sa->load_sum += weight * contrib;

			if (cfs_rq)

				cfs_rq->runnable_load_sum += weight * contrib;

		}

		if (running)

			sa->util_sum += contrib * scale_freq >> SCHED_CAPACITY_SHIFT;

	}



	/* Remainder of delta accrued against u_0` */

	if (weight)

	if (weight) {

		sa->load_sum += weight * delta;

		if (cfs_rq)

			cfs_rq->runnable_load_sum += weight * delta;

	}

	if (running)

		sa->util_sum += delta * scale_freq >> SCHED_CAPACITY_SHIFT;
@@ -2614,6 +2627,10 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa, 


	if (decayed) {

		sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX);

		if (cfs_rq) {

			cfs_rq->runnable_load_avg =

				div_u64(cfs_rq->runnable_load_sum, LOAD_AVG_MAX);

		}

		sa->util_avg = (sa->util_sum << SCHED_LOAD_SHIFT) / LOAD_AVG_MAX;

	}
@@ -2661,7 +2678,7 @@ static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) 
	}



	decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,

		scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL);

		scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL, cfs_rq);



#ifndef CONFIG_64BIT

	smp_wmb();
@@ -2683,7 +2700,7 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg) 
	 * track group sched_entity load average for task_h_load calc in migration

	 */

	__update_load_avg(now, cpu, &se->avg,

		se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);

		se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se, NULL);



	if (update_cfs_rq_load_avg(now, cfs_rq) && update_tg)

		update_tg_load_avg(cfs_rq, 0);
@@ -2703,11 +2720,15 @@ enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) 
	}

	else {

		__update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,

			se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);

			se->on_rq * scale_load_down(se->load.weight),

			cfs_rq->curr == se, NULL);

	}



	decayed = update_cfs_rq_load_avg(now, cfs_rq);



	cfs_rq->runnable_load_avg += sa->load_avg;

	cfs_rq->runnable_load_sum += sa->load_sum;



	if (migrated) {

		cfs_rq->avg.load_avg += sa->load_avg;

		cfs_rq->avg.load_sum += sa->load_sum;
@@ -2719,6 +2740,18 @@ enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) 
		update_tg_load_avg(cfs_rq, 0);

}



/* Remove the runnable load generated by se from cfs_rq's runnable load average */

static inline void

dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	update_load_avg(se, 1);



	cfs_rq->runnable_load_avg =

		max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0);

	cfs_rq->runnable_load_sum =

		max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0);

}



/*

 * Task first catches up with cfs_rq, and then subtract

 * itself from the cfs_rq (task must be off the queue now).
@@ -2740,7 +2773,7 @@ void remove_entity_load_avg(struct sched_entity *se) 
	last_update_time = cfs_rq->avg.last_update_time;

#endif



	__update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0);

	__update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0, NULL);

	atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);

	atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg);

}
@@ -2770,6 +2803,8 @@ static int idle_balance(struct rq *this_rq); 
static inline void update_load_avg(struct sched_entity *se, int update_tg) {}

static inline void

enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}

static inline void

dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}

static inline void remove_entity_load_avg(struct sched_entity *se) {}



static inline int idle_balance(struct rq *rq)
@@ -2977,7 +3012,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) 
	 * Update run-time statistics of the 'current'.

	 */

	update_curr(cfs_rq);

	update_load_avg(se, 1);

	dequeue_entity_load_avg(cfs_rq, se);



	update_stats_dequeue(cfs_rq, se);

	if (flags & DEQUEUE_SLEEP) {
@@ -7863,7 +7898,7 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) 
#ifdef CONFIG_SMP

	/* Catch up with the cfs_rq and remove our load when we leave */

	__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq), &se->avg,

		se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);

		se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se, NULL);



	cfs_rq->avg.load_avg =

		max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);

kernel/sched/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -368,6 +368,8 @@ struct cfs_rq { 
	 * CFS load tracking

	 */

	struct sched_avg avg;

	u64 runnable_load_sum;

	unsigned long runnable_load_avg;

#ifdef CONFIG_FAIR_GROUP_SCHED

	unsigned long tg_load_avg_contrib;

#endif