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Commit 8b911acd authored by Mike Galbraith's avatar Mike Galbraith Committed by Ingo Molnar
Browse files

sched: Fix select_idle_sibling() 



Don't bother with selection when the current cpu is idle.  Recent load
balancing changes also make it no longer necessary to check wake_affine()
success before returning the selected sibling, so we now always use it.

Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301369.6785.36.camel@marge.simson.net>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 21406928

kernel/sched_fair.c

+10 −4
Original line number Diff line number Diff line
@@ -1439,7 +1439,7 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag 
	int cpu = smp_processor_id();

	int prev_cpu = task_cpu(p);

	int new_cpu = cpu;

	int want_affine = 0;

	int want_affine = 0, cpu_idle = !current->pid;

	int want_sd = 1;

	int sync = wake_flags & WF_SYNC;
@@ -1497,13 +1497,15 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag 
			 * If there's an idle sibling in this domain, make that

			 * the wake_affine target instead of the current cpu.

			 */

			if (tmp->flags & SD_SHARE_PKG_RESOURCES)

			if (!cpu_idle && tmp->flags & SD_SHARE_PKG_RESOURCES)

				target = select_idle_sibling(p, tmp, target);



			if (target >= 0) {

				if (tmp->flags & SD_WAKE_AFFINE) {

					affine_sd = tmp;

					want_affine = 0;

					if (target != cpu)

						cpu_idle = 1;

				}

				cpu = target;

			}
@@ -1519,6 +1521,7 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag 
			sd = tmp;

	}



#ifdef CONFIG_FAIR_GROUP_SCHED

	if (sched_feat(LB_SHARES_UPDATE)) {

		/*

		 * Pick the largest domain to update shares over
@@ -1532,9 +1535,12 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag 
		if (tmp)

			update_shares(tmp);

	}

#endif



	if (affine_sd && wake_affine(affine_sd, p, sync))

	if (affine_sd) {

		if (cpu_idle || cpu == prev_cpu || wake_affine(affine_sd, p, sync))

			return cpu;

	}



	while (sd) {

		int load_idx = sd->forkexec_idx;