linux-kernel - [tip:sched/core] sched/fair: Optimize find_busiest

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Date:	Mon, 2 Sep 2013 00:41:07 -0700
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	preeti@...ux.vnet.ibm.com, pjt@...gle.com, peterz@...radead.org,
	tglx@...utronix.de
Subject: [tip:sched/core] sched/fair: Optimize find_busiest_queue()

Commit-ID:  6906a40839198f33dbb56d20e644c01e00663952
Gitweb:     http://git.kernel.org/tip/6906a40839198f33dbb56d20e644c01e00663952
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Mon, 19 Aug 2013 15:20:21 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 2 Sep 2013 08:27:37 +0200

sched/fair: Optimize find_busiest_queue()

Use for_each_cpu_and() and thereby avoid computing the capacity for
CPUs we know we're not interested in.

Reviewed-by: Paul Turner <pjt@...gle.com>
Reviewed-by: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/n/tip-lppceyv6kb3a19g8spmrn20b@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ccf20e7..bedd30b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4946,7 +4946,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 	unsigned long busiest_load = 0, busiest_power = 1;
 	int i;
 
-	for_each_cpu(i, sched_group_cpus(group)) {
+	for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
 		unsigned long power = power_of(i);
 		unsigned long capacity = DIV_ROUND_CLOSEST(power,
 							   SCHED_POWER_SCALE);
@@ -4955,9 +4955,6 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 		if (!capacity)
 			capacity = fix_small_capacity(env->sd, group);
 
-		if (!cpumask_test_cpu(i, env->cpus))
-			continue;
-
 		rq = cpu_rq(i);
 		wl = weighted_cpuload(i);
 
--
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