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From: "tip-bot2 for Vincent Guittot" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Mel Gorman <mgorman@suse.de>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: sched/core] sched/fair: Skip idle cfs_rq
Date: Thu, 14 Jan 2021 11:29:06 -0000	[thread overview]
Message-ID: <161062374612.414.2070261593329416590.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210107103325.30851-2-vincent.guittot@linaro.org>

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     fc488ffd4297f661b3e9d7450dcdb9089a53df7c
Gitweb:        https://git.kernel.org/tip/fc488ffd4297f661b3e9d7450dcdb9089a53df7c
Author:        Vincent Guittot <vincent.guittot@linaro.org>
AuthorDate:    Thu, 07 Jan 2021 11:33:23 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 14 Jan 2021 11:20:10 +01:00

sched/fair: Skip idle cfs_rq

Don't waste time checking whether an idle cfs_rq could be the busiest
queue. Furthermore, this can end up selecting a cfs_rq with a high load
but being idle in case of migrate_load.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20210107103325.30851-2-vincent.guittot@linaro.org
---
 kernel/sched/fair.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 40d3ebf..13de7ae 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9402,8 +9402,11 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 		if (rt > env->fbq_type)
 			continue;
 
-		capacity = capacity_of(i);
 		nr_running = rq->cfs.h_nr_running;
+		if (!nr_running)
+			continue;
+
+		capacity = capacity_of(i);
 
 		/*
 		 * For ASYM_CPUCAPACITY domains, don't pick a CPU that could

  parent reply	other threads:[~2021-01-14 11:30 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-07 10:33 [PATCH 0/3 v2] Reduce number of active LB Vincent Guittot
2021-01-07 10:33 ` [PATCH 1/3 v2] sched/fair: skip idle cfs_rq Vincent Guittot
2021-01-11 14:46   ` Mel Gorman
2021-01-14 11:29   ` tip-bot2 for Vincent Guittot [this message]
2021-01-07 10:33 ` [PATCH 2/3 v2] sched/fair: don't set LBF_ALL_PINNED unnecessarily Vincent Guittot
2021-01-07 11:26   ` Valentin Schneider
     [not found]   ` <BN8PR12MB2978EC9CFBAF529C527D05919AAF0@BN8PR12MB2978.namprd12.prod.outlook.com>
2021-01-07 16:00     ` Vincent Guittot
2021-01-11 15:42   ` Mel Gorman
2021-01-14 11:29   ` [tip: sched/core] sched/fair: Don't " tip-bot2 for Vincent Guittot
2021-01-07 10:33 ` [PATCH 3/3 v2] sched/fair: reduce cases for active balance Vincent Guittot
2021-01-07 11:26   ` Valentin Schneider
2021-01-07 12:20     ` Vincent Guittot
2021-01-07 17:40       ` Valentin Schneider
2021-01-08  8:11         ` Vincent Guittot
2021-01-08 14:36           ` Valentin Schneider
2021-01-12  9:16   ` Mel Gorman
2021-01-14 11:29   ` [tip: sched/core] sched/fair: Reduce " tip-bot2 for Vincent Guittot

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