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Commit e54faa52 authored by Steve Muckle's avatar Steve Muckle Committed by Gerrit - the friendly Code Review server
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sched: add sync wakeup recognition in select_best_cpu 



If a wakeup is a sync wakeup, we need to discount the currently
running task's load from the waker's CPU as we calculate the best
CPU for the waking task to land on.

Also fix an oversight in the small task wakeup path, the spill
threshold check there was not sync-wakeup aware.

Change-Id: I00c5df626d17868323d60fb90b4513c0dd314825
Signed-off-by: default avatarSteve Muckle <smuckle@codeaurora.org>
parent 2a90f72c

kernel/sched/fair.c

+17 −14
Original line number Diff line number Diff line
@@ -1458,9 +1458,11 @@ static inline u64 cpu_load_sync(int cpu, int sync) 
}



static int

spill_threshold_crossed(struct task_struct *p, struct rq *rq, int cpu)

spill_threshold_crossed(struct task_struct *p, struct rq *rq, int cpu,

			int sync)

{

	u64 total_load = cpu_load(cpu) + scale_load_to_cpu(task_load(p), cpu);

	u64 total_load = cpu_load_sync(cpu, sync) +

		scale_load_to_cpu(task_load(p), cpu);



	if (total_load > sched_spill_load ||

	    (rq->nr_running + 1) > sysctl_sched_spill_nr_run)
@@ -1612,15 +1614,15 @@ static int task_will_fit(struct task_struct *p, int cpu) 
	return 0;

}



static int eligible_cpu(struct task_struct *p, int cpu)

static int eligible_cpu(struct task_struct *p, int cpu, int sync)

{

	struct rq *rq = cpu_rq(cpu);



	if (mostly_idle_cpu(cpu))

	if (mostly_idle_cpu_sync(cpu, sync))

		return 1;



	if (rq->capacity != max_capacity)

		return !spill_threshold_crossed(p, rq, cpu);

		return !spill_threshold_crossed(p, rq, cpu, sync);



	return 0;

}
@@ -1799,7 +1801,7 @@ static int best_small_task_cpu(struct task_struct *p, int sync) 
		 * lowest power band that we've seen?

		 */

		if (load < best_busy_lowpower_cpu_load &&

		    !spill_threshold_crossed(p, rq, i)) {

		    !spill_threshold_crossed(p, rq, i, sync)) {

			best_busy_lowpower_cpu = i;

			best_busy_lowpower_cpu_load = load;

		}
@@ -1877,7 +1879,7 @@ static int select_best_cpu(struct task_struct *p, int target, int reason, 
			continue;



		trace_sched_cpu_load(cpu_rq(i), idle_cpu(i),

				     mostly_idle_cpu(i), power_cost(p, i));

				     mostly_idle_cpu_sync(i, sync), power_cost(p, i));



		/*

		 * The least-loaded mostly-idle CPU where the task
@@ -1885,8 +1887,8 @@ static int select_best_cpu(struct task_struct *p, int target, int reason, 
		 * where the task will fit.

		 */

		if (!task_will_fit(p, i)) {

			if (mostly_idle_cpu(i)) {

				load = cpu_load(i);

			if (mostly_idle_cpu_sync(i, sync)) {

				load = cpu_load_sync(i, sync);

				if (load < min_fallback_load) {

					min_fallback_load = load;

					fallback_idle_cpu = i;
@@ -1895,7 +1897,7 @@ static int select_best_cpu(struct task_struct *p, int target, int reason, 
			continue;

		}



		if (!eligible_cpu(p, i))

		if (!eligible_cpu(p, i, sync))

			continue;



		/*
@@ -1904,7 +1906,7 @@ static int select_best_cpu(struct task_struct *p, int target, int reason, 
		 * spill.

		 */



		load = cpu_load(i);

		load = cpu_load_sync(i, sync);

		cpu_cost = power_cost(p, i);

		cstate = cpu_rq(i)->cstate;
@@ -1971,8 +1973,9 @@ static int select_best_cpu(struct task_struct *p, int target, int reason, 
		}

	}



	if (min_cstate_cpu >= 0 && (sysctl_sched_prefer_idle ||

			!(best_cpu >= 0 && mostly_idle_cpu(best_cpu))))

	if (min_cstate_cpu >= 0 &&

	    (sysctl_sched_prefer_idle ||

	     !(best_cpu >= 0 && mostly_idle_cpu_sync(best_cpu, sync))))

		best_cpu = min_cstate_cpu;

done:

	if (best_cpu < 0) {
@@ -2361,7 +2364,7 @@ static inline int power_cost(struct task_struct *p, int cpu) 
}



static inline int

spill_threshold_crossed(struct task_struct *p, struct rq *rq, int cpu)

spill_threshold_crossed(struct task_struct *p, struct rq *rq, int cpu, int sync)

{

	return 0;

}