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Commit 1323302a authored by Pavankumar Kondeti's avatar Pavankumar Kondeti
Browse files

sched/fair: Skips the CPUs which can't fit the task 



The current task placement code does not explicitly check
if a task fits on a CPU or not. Instead it relies on other
checks like new utilization is not above CPU's original
capacity and CPU has enough head room after accommodating
this task. These does not take the sched_upmigrate and
sched_downmigrate thresholds into account. Add an explicit
check to skip sched group that can't fit the task.

Change-Id: I49e9fdbe7490654d7b8fe08034dba2b29173e5db
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent 9fff4080

kernel/sched/fair.c

+26 −14
Original line number Diff line number Diff line
@@ -6953,11 +6953,29 @@ static inline bool task_fits_max(struct task_struct *p, int cpu) 


	if (sched_boost_policy() == SCHED_BOOST_ON_BIG &&

					task_sched_boost(p))

		return false;

		return !is_min_capacity_cpu(cpu);



	return task_fits_capacity(p, capacity, cpu);

}



static inline bool skip_sg(struct task_struct *p, struct sched_group *sg,

			   struct cpumask *rtg_target)

{

	int fcpu = group_first_cpu(sg);



	/* Are all CPUs isolated in this group? */

	if (!sg->group_weight)

		return true;



	if (!task_fits_max(p, fcpu))

		return true;



	if (rtg_target && !cpumask_test_cpu(fcpu, rtg_target))

		return true;



	return false;

}



static int start_cpu(bool boosted)

{

	struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -7001,6 +7019,9 @@ static inline int find_best_target(struct task_struct *p, int *backup_cpu, 
	/* Scan CPUs in all SDs */

	sg = sd->groups;

	do {

		if (skip_sg(p, sg, rtg_target))

			continue;



		for_each_cpu_and(i, &p->cpus_allowed, sched_group_span(sg)) {

			unsigned long capacity_curr = capacity_curr_of(i);

			unsigned long capacity_orig = capacity_orig_of(i);
@@ -7020,9 +7041,6 @@ static inline int find_best_target(struct task_struct *p, int *backup_cpu, 
			if (sched_cpu_high_irqload(i))

				continue;



			if (rtg_target && !cpumask_test_cpu(i, rtg_target))

				break;



			/*

			 * p's blocked utilization is still accounted for on prev_cpu

			 * so prev_cpu will receive a negative bias due to the double
@@ -7032,23 +7050,17 @@ static inline int find_best_target(struct task_struct *p, int *backup_cpu, 
			new_util = wake_util + task_util(p);

			spare_cap = capacity_orig_of(i) - wake_util;



			switch (placement_boost) {

			/*

			 * pick lowest util cpu amongst all > min cap

			 * CPUs

			 * When placement boost is active, we traverse CPUs

			 * other than min capacity CPUs. Pick the CPU which

			 * has the maximum spare capacity.

			 */

			case SCHED_BOOST_ON_BIG:

				if (is_min_capacity_cpu(i))

					continue;



			if (placement_boost) {

				if (spare_cap > target_max_spare_cap) {

					target_cpu = i;

					target_max_spare_cap = spare_cap;

				}

				continue;



			default:

				break;

			}



			/*