From: Morten Rasmussen <morten.rasmussen@arm.com>
To: peterz@infradead.org, mingo@redhat.com
Cc: dietmar.eggemann@arm.com, yuyang.du@intel.com,
vincent.guittot@linaro.org, mgalbraith@suse.de,
sgurrappadi@nvidia.com, freedom.tan@mediatek.com,
keita.kobayashi.ym@renesas.com, linux-kernel@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: [PATCH v3 03/13] sched/fair: Optimize find_idlest_cpu() when there is no choice
Date: Mon, 25 Jul 2016 14:34:20 +0100 [thread overview]
Message-ID: <1469453670-2660-4-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1469453670-2660-1-git-send-email-morten.rasmussen@arm.com>
In the current find_idlest_group()/find_idlest_cpu() search we end up
calling find_idlest_cpu() in a sched_group containing only one cpu in
the end. Checking idle-states becomes pointless when there is no
alternative, so bail out instead.
cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
kernel/sched/fair.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e7d50acd6028..c1c0aa8b300b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5229,6 +5229,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
int shallowest_idle_cpu = -1;
int i;
+ /* Check if we have any choice */
+ if (group->group_weight == 1)
+ return cpumask_first(sched_group_cpus(group));
+
/* Traverse only the allowed CPUs */
for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
if (idle_cpu(i)) {
--
1.9.1
next prev parent reply other threads:[~2016-07-25 13:35 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-25 13:34 [PATCH v3 00/13] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 01/13] sched: Fix power to capacity renaming in comment Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 02/13] sched/fair: Consistent use of prev_cpu in wakeup path Morten Rasmussen
2016-07-25 13:34 ` Morten Rasmussen [this message]
2016-07-25 13:34 ` [PATCH v3 04/13] sched/core: Remove unnecessary null-pointer check Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Remove unnecessary NULL-pointer check tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Morten Rasmussen
2016-08-15 10:54 ` Peter Zijlstra
2016-08-15 11:43 ` Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Clarify SD_flags comment tip-bot for Peter Zijlstra
2016-08-17 8:42 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Wanpeng Li
2016-08-17 9:23 ` Morten Rasmussen
2016-08-17 9:26 ` Wanpeng Li
2016-08-18 10:56 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 06/13] sched/core: Pass child domain into sd_init Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: Pass child domain into sd_init() tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 07/13] sched: Enable SD_BALANCE_WAKE for asymmetric capacity systems Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 08/13] sched: Store maximum per-cpu capacity in root domain Morten Rasmussen
2016-08-01 18:53 ` Dietmar Eggemann
2016-08-16 12:24 ` Vincent Guittot
2016-08-18 10:58 ` [tip:sched/core] sched/core: Store maximum per-CPU " tip-bot for Dietmar Eggemann
2016-07-25 13:34 ` [PATCH v3 09/13] sched/fair: Let asymmetric cpu configurations balance at wake-up Morten Rasmussen
2016-08-15 13:39 ` Peter Zijlstra
2016-08-15 15:01 ` Morten Rasmussen
2016-08-15 15:10 ` Peter Zijlstra
2016-08-15 15:30 ` Morten Rasmussen
2016-08-18 10:58 ` [tip:sched/core] sched/fair: Let asymmetric CPU " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 10/13] sched/fair: Compute task/cpu utilization at wake-up more correctly Morten Rasmussen
2016-08-15 14:23 ` Peter Zijlstra
2016-08-15 15:42 ` Morten Rasmussen
2016-08-18 8:40 ` Morten Rasmussen
2016-08-18 10:24 ` Morten Rasmussen
2016-08-18 11:46 ` Wanpeng Li
2016-08-18 13:45 ` Morten Rasmussen
2016-08-19 1:43 ` Wanpeng Li
2016-08-19 14:03 ` Morten Rasmussen
2016-08-22 1:48 ` Wanpeng Li
2016-08-22 11:29 ` Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 11/13] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-08-16 13:57 ` Vincent Guittot
2016-08-18 11:16 ` Morten Rasmussen
2016-08-18 12:28 ` Peter Zijlstra
2016-07-25 13:34 ` [PATCH v3 12/13] sched: Add per-cpu min capacity to sched_group_capacity Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 13/13] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
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