Commit 8651a86c authored by Srivatsa Vaddagiri's avatar Srivatsa Vaddagiri Committed by Ingo Molnar
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sched: group scheduler wakeup latency fix 



group scheduler wakeup latency fix: when checking for preemption
we must check cross-group too, not just intra-group.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 57cb499d

kernel/sched_fair.c

+16 −5
Original line number Diff line number Diff line
@@ -796,7 +796,8 @@ static void yield_task_fair(struct rq *rq) 
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)

{

	struct task_struct *curr = rq->curr;

	struct cfs_rq *cfs_rq = task_cfs_rq(curr);

	struct cfs_rq *cfs_rq = task_cfs_rq(curr), *pcfs_rq;

	struct sched_entity *se = &curr->se, *pse = &p->se;



	if (unlikely(rt_prio(p->prio))) {

		update_rq_clock(rq);
@@ -804,11 +805,21 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) 
		resched_task(curr);

		return;

	}

	if (is_same_group(curr, p)) {

		s64 delta = curr->se.vruntime - p->se.vruntime;



	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		pcfs_rq = cfs_rq_of(pse);



		if (cfs_rq == pcfs_rq) {

			s64 delta = se->vruntime - pse->vruntime;



			if (delta > (s64)sysctl_sched_wakeup_granularity)

				resched_task(curr);

			break;

		}

#ifdef CONFIG_FAIR_GROUP_SCHED

		pse = pse->parent;

#endif

	}

}