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From: Valentin Schneider <valentin.schneider@arm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, peterz@infradead.org,
	vincent.guittot@linaro.org, morten.rasmussen@arm.com,
	Dietmar.Eggemann@arm.com
Subject: [PATCH 1/5] sched/fair: Use for_each_cpu_and for asym-packing nohz kicks
Date: Thu, 17 Jan 2019 15:34:07 +0000	[thread overview]
Message-ID: <20190117153411.2390-2-valentin.schneider@arm.com> (raw)
In-Reply-To: <20190117153411.2390-1-valentin.schneider@arm.com>

Calling 'nohz_balance_exit_idle(rq)' will always clear 'rq->cpu' from
'nohz.idle_cpus_mask' if it is set. Since it is called at the top of
'nohz_balancer_kick()', 'rq->cpu' will never be set in
'nohz.idle_cpus_mask' if it is accessed in the rest of the function.

"And" the 'sched_domain_span()' with 'nohz.idle_cpus_mask' and drop the
'(i == cpu)' check since 'rq->cpu' will never be iterated over.

While at it, clean up a condition alignment.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
---
 kernel/sched/fair.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ca469646ebe1..380a72e42678 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9557,7 +9557,7 @@ static void nohz_balancer_kick(struct rq *rq)
 	sd = rcu_dereference(rq->sd);
 	if (sd) {
 		if ((rq->cfs.h_nr_running >= 1) &&
-				check_cpu_capacity(rq, sd)) {
+		    check_cpu_capacity(rq, sd)) {
 			flags = NOHZ_KICK_MASK;
 			goto unlock;
 		}
@@ -9565,11 +9565,7 @@ static void nohz_balancer_kick(struct rq *rq)
 
 	sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
 	if (sd) {
-		for_each_cpu(i, sched_domain_span(sd)) {
-			if (i == cpu ||
-			    !cpumask_test_cpu(i, nohz.idle_cpus_mask))
-				continue;
-
+		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
 			if (sched_asym_prefer(i, cpu)) {
 				flags = NOHZ_KICK_MASK;
 				goto unlock;
-- 
2.20.1


  reply	other threads:[~2019-01-17 15:37 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-17 15:34 [PATCH 0/5] sched/fair: NOHZ cleanups and misfit improvement Valentin Schneider
2019-01-17 15:34 ` Valentin Schneider [this message]
2019-02-11 10:50   ` [tip:sched/core] sched/fair: Simplify nohz_balancer_kick() tip-bot for Valentin Schneider
2019-01-17 15:34 ` [PATCH 2/5] sched/fair: Explain LLC nohz kick condition Valentin Schneider
2019-02-11 10:51   ` [tip:sched/core] " tip-bot for Valentin Schneider
2019-01-17 15:34 ` [PATCH 3/5] sched/fair: Prune nohz_balancer_kick() comment block Valentin Schneider
2019-02-11 10:51   ` [tip:sched/core] sched/fair: Prune, fix and simplify the " tip-bot for Valentin Schneider
2019-01-17 15:34 ` [PATCH 4/5] sched/fair: Tune down misfit nohz kicks Valentin Schneider
2019-02-06 16:04   ` Peter Zijlstra
2019-02-06 17:25     ` Valentin Schneider
2019-02-07  9:57       ` Peter Zijlstra
2019-01-17 15:34 ` [PATCH 5/5] sched/fair: Skip LLC nohz logic for asymmetric systems Valentin Schneider
2019-02-06 16:14   ` Peter Zijlstra
2019-02-06 17:26     ` Valentin Schneider
2019-02-07  9:56       ` Peter Zijlstra
2019-02-07 11:31         ` Valentin Schneider
2019-02-06 14:33 ` [PATCH 0/5] sched/fair: NOHZ cleanups and misfit improvement Valentin Schneider

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