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Commit a2f5c9ab authored by Darren Hart's avatar Darren Hart Committed by Ingo Molnar
Browse files

sched: Allow SCHED_BATCH to preempt SCHED_IDLE tasks 



Perform the test for SCHED_IDLE before testing for SCHED_BATCH (and
ensure idle tasks don't preempt idle tasks) so the non-interactive,
but still important, SCHED_BATCH tasks will run in favor of the very
low priority SCHED_IDLE tasks.

Signed-off-by: default avatarDarren Hart <dvhart@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarMike Galbraith <efault@gmx.de>
Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
LKML-Reference: <1298408674-3130-2-git-send-email-dvhart@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e0a92c17

kernel/sched_fair.c

+7 −5
Original line number Diff line number Diff line
@@ -1870,16 +1870,18 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ 
	if (test_tsk_need_resched(curr))

		return;



	/* Idle tasks are by definition preempted by non-idle tasks. */

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

	    likely(p->policy != SCHED_IDLE))

		goto preempt;



	/*

	 * Batch and idle tasks do not preempt (their preemption is driven by

	 * the tick):

	 * Batch and idle tasks do not preempt non-idle tasks (their preemption

	 * is driven by the tick):

	 */

	if (unlikely(p->policy != SCHED_NORMAL))

		return;



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

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

		goto preempt;



	if (!sched_feat(WAKEUP_PREEMPT))

		return;