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Commit fe3bcfe1 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: More generic WAKE_AFFINE vs select_idle_sibling() 



Instead of only considering SD_WAKE_AFFINE | SD_PREFER_SIBLING
domains also allow all SD_PREFER_SIBLING domains below a
SD_WAKE_AFFINE domain to change the affinity target.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091112145610.909723612@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a50bde51

kernel/sched_fair.c

+16 −17
Original line number Diff line number Diff line
@@ -1333,22 +1333,18 @@ select_idle_sibling(struct task_struct *p, struct sched_domain *sd, int target) 
	 * test in select_task_rq_fair) and the prev_cpu is idle then that's

	 * always a better target than the current cpu.

	 */

	if (target == cpu) {

		if (!cpu_rq(prev_cpu)->cfs.nr_running)

			target = prev_cpu;

	}

	if (target == cpu && !cpu_rq(prev_cpu)->cfs.nr_running)

		return prev_cpu;



	/*

	 * Otherwise, iterate the domain and find an elegible idle cpu.

	 */

	if (target == -1 || target == cpu) {

	for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {

		if (!cpu_rq(i)->cfs.nr_running) {

			target = i;

			break;

		}

	}

	}



	return target;

}
@@ -1407,7 +1403,12 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag 
				want_sd = 0;

		}



		if (want_affine && (tmp->flags & SD_WAKE_AFFINE)) {

		/*

		 * While iterating the domains looking for a spanning

		 * WAKE_AFFINE domain, adjust the affine target to any idle cpu

		 * in cache sharing domains along the way.

		 */

		if (want_affine) {

			int target = -1;



			/*
@@ -1420,17 +1421,15 @@ 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.

			 *

			 * XXX: should we possibly do this outside of

			 * WAKE_AFFINE, in case the shared cache domain is

			 * smaller than the WAKE_AFFINE domain?

			 */

			if (tmp->flags & SD_PREFER_SIBLING)

				target = select_idle_sibling(p, tmp, target);



			if (target >= 0) {

				if (tmp->flags & SD_WAKE_AFFINE) {

					affine_sd = tmp;

					want_affine = 0;

				}

				cpu = target;

			}

		}