linux-kernel - [PATCH 25/39] autonuma: fix selecting idle sibling

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Date:	Mon, 26 Mar 2012 19:46:12 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:	Hillf Danton <dhillf@...il.com>, Dan Smith <danms@...ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Mike Galbraith <efault@....de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Bharata B Rao <bharata.rao@...il.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH 25/39] autonuma: fix selecting idle sibling

From: Hillf Danton <dhillf@...il.com>

Autonuma cpu is selected only from the idle group without the requirement that
each cpu in the group is autonuma for given task.

Signed-off-by: Hillf Danton <dhillf@...il.com>
Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 kernel/sched/fair.c |   25 +++++++++++++------------
 1 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bf109cc..0d2fe26 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2642,7 +2642,6 @@ static int select_idle_sibling(struct task_struct *p, int target)
 	struct sched_domain *sd;
 	struct sched_group *sg;
 	int i;
-	bool numa;
 
 	/*
 	 * If the task is going to be woken-up on this cpu and if it is
@@ -2662,8 +2661,6 @@ static int select_idle_sibling(struct task_struct *p, int target)
 	/*
 	 * Otherwise, iterate the domains and find an elegible idle cpu.
 	 */
-	numa = true;
-again:
 	sd = rcu_dereference(per_cpu(sd_llc, target));
 	for_each_lower_domain(sd) {
 		sg = sd->groups;
@@ -2673,22 +2670,26 @@ again:
 				goto next;
 
 			for_each_cpu(i, sched_group_cpus(sg)) {
-				if (!idle_cpu(i) ||
-				    (numa && !task_autonuma_cpu(p, i)))
+				if (!idle_cpu(i))
 					goto next;
 			}
 
-			target = cpumask_first_and(sched_group_cpus(sg),
-					tsk_cpus_allowed(p));
-			goto done;
+			cpu = -1;
+			for_each_cpu_and(i, sched_group_cpus(sg),
+						tsk_cpus_allowed(p)) {
+				/* Find autonuma cpu only in idle group */
+				if (task_autonuma_cpu(p, i)) {
+					target = i;
+					goto done;
+				}
+				if (cpu == -1)
+					cpu = i;
+			}
+			target = cpu;
 next:
 			sg = sg->next;
 		} while (sg != sd->groups);
 	}
-	if (numa) {
-		numa = false;
-		goto again;
-	}
 done:
 	return target;
 }
--
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