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Commit 3a7e73a2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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sched: Clean up check_preempt_wakeup() 



Streamline the wakeup preemption code a bit, unifying the preempt path
so that they all do the same.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a65ac745

kernel/sched_fair.c

+33 −40
Original line number Diff line number Diff line
@@ -1651,10 +1651,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ 
	int sync = wake_flags & WF_SYNC;

	int scale = cfs_rq->nr_running >= sched_nr_latency;



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

		resched_task(curr);

		return;

	}

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

		goto preempt;



	if (unlikely(p->sched_class != &fair_sched_class))

		return;
@@ -1680,37 +1678,32 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ 
		return;



	/* Idle tasks are by definition preempted by everybody. */

	if (unlikely(curr->policy == SCHED_IDLE)) {

		resched_task(curr);

		return;

	}

	if (unlikely(curr->policy == SCHED_IDLE))

		goto preempt;



	if ((sched_feat(WAKEUP_SYNC) && sync) ||

	    (sched_feat(WAKEUP_OVERLAP) &&

	     (se->avg_overlap < sysctl_sched_migration_cost &&

	      pse->avg_overlap < sysctl_sched_migration_cost))) {

		resched_task(curr);

		return;

	}

	if (sched_feat(WAKEUP_SYNC) && sync)

		goto preempt;



	if (sched_feat(WAKEUP_RUNNING)) {

		if (pse->avg_running < se->avg_running) {

			set_next_buddy(pse);

			resched_task(curr);

			return;

		}

	}

	if (sched_feat(WAKEUP_OVERLAP) &&

			se->avg_overlap < sysctl_sched_migration_cost &&

			pse->avg_overlap < sysctl_sched_migration_cost)

		goto preempt;



	if (sched_feat(WAKEUP_RUNNING) && pse->avg_running < se->avg_running)

		goto preempt;



	if (!sched_feat(WAKEUP_PREEMPT))

		return;



	update_curr(cfs_rq);

	find_matching_se(&se, &pse);



	BUG_ON(!pse);

	if (wakeup_preempt_entity(se, pse) == 1)

		goto preempt;



	update_curr(cfs_rq);

	return;



	if (wakeup_preempt_entity(se, pse) == 1) {

preempt:

	resched_task(curr);

	/*

	 * Only set the backward buddy when the current task is still
@@ -1723,10 +1716,10 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ 
	 */

	if (unlikely(!se->on_rq || curr == rq->idle))

		return;



	if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))

		set_last_buddy(se);

}

}



static struct task_struct *pick_next_task_fair(struct rq *rq)

{