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Commit 5250fc5d authored by Pavankumar Kondeti's avatar Pavankumar Kondeti Committed by Gerrit - the friendly Code Review server
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sched/fair: Force gold cpus to do idle lb when silver has big tasks 



We often see traces that gold cpus goes to idle even when silver
has big tasks. This is because avg_idle checks does not allow
the gold cpus to enter idle balance. This is NOT okay when
silver CPUs have big tasks.

Change-Id: Ice00d43c70be105b5bc3ad09caa6047aa98d7402
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: default avatarRunmin Wang <runminw@codeaurora.org>
parent 041ae774

kernel/sched/fair.c

+19 −3
Original line number Diff line number Diff line
@@ -11549,6 +11549,20 @@ static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle 
static inline void nohz_newidle_balance(struct rq *this_rq) { }

#endif /* CONFIG_NO_HZ_COMMON */



static bool silver_has_big_tasks(void)

{

	int cpu;



	for_each_possible_cpu(cpu) {

		if (!is_min_capacity_cpu(cpu))

			break;

		if (cpu_rq(cpu)->walt_stats.nr_big_tasks)

			return true;

	}



	return false;

}



/*

 * idle_balance is called by schedule() if this_cpu is about to become

 * idle. Attempts to pull tasks from other CPUs.
@@ -11560,6 +11574,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) 
	struct sched_domain *sd;

	int pulled_task = 0;

	u64 curr_cost = 0;

	u64 avg_idle = this_rq->avg_idle;



	if (cpu_isolated(this_cpu))

		return 0;
@@ -11575,7 +11590,8 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) 
	 */

	if (!cpu_active(this_cpu))

		return 0;



	if (!is_min_capacity_cpu(this_cpu) && silver_has_big_tasks())

		avg_idle = ULLONG_MAX;

	/*

	 * This is OK, because current is on_cpu, which avoids it being picked

	 * for load-balance and preemption/IRQs are still disabled avoiding
@@ -11584,7 +11600,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) 
	 */

	rq_unpin_lock(this_rq, rf);



	if (this_rq->avg_idle < sysctl_sched_migration_cost ||

	if (avg_idle < sysctl_sched_migration_cost ||

	    !READ_ONCE(this_rq->rd->overload)) {



		rcu_read_lock();
@@ -11609,7 +11625,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) 
		if (!(sd->flags & SD_LOAD_BALANCE))

			continue;



		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {

		if (avg_idle < curr_cost + sd->max_newidle_lb_cost) {

			update_next_balance(sd, &next_balance);

			break;

		}