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
next prev parent 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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