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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>,
	Phil Auld <pauld@redhat.com>, x86 <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [tip: sched/core] sched/fair: Reduce busy load balance interval
Date: Tue, 29 Sep 2020 07:56:48 -0000	[thread overview]
Message-ID: <160136620854.7002.17745483479490087690.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200921072424.14813-5-vincent.guittot@linaro.org>

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

Commit-ID:     6e7499135db724539ca887b3aa64122502875c71
Gitweb:        https://git.kernel.org/tip/6e7499135db724539ca887b3aa64122502875c71
Author:        Vincent Guittot <vincent.guittot@linaro.org>
AuthorDate:    Mon, 21 Sep 2020 09:24:24 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 25 Sep 2020 14:23:26 +02:00

sched/fair: Reduce busy load balance interval

The busy_factor, which increases load balance interval when a cpu is busy,
is set to 32 by default. This value generates some huge LB interval on
large system like the THX2 made of 2 node x 28 cores x 4 threads.
For such system, the interval increases from 112ms to 3584ms at MC level.
And from 228ms to 7168ms at NUMA level.

Even on smaller system, a lower busy factor has shown improvement on the
fair distribution of the running time so let reduce it for all.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200921072424.14813-5-vincent.guittot@linaro.org
---
 kernel/sched/topology.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 41df628..a3a2417 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1348,7 +1348,7 @@ sd_init(struct sched_domain_topology_level *tl,
 	*sd = (struct sched_domain){
 		.min_interval		= sd_weight,
 		.max_interval		= 2*sd_weight,
-		.busy_factor		= 32,
+		.busy_factor		= 16,
 		.imbalance_pct		= 117,
 
 		.cache_nice_tries	= 0,

  parent reply	other threads:[~2020-09-29  7:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21  7:24 [PATCH 0/4 v2] sched/fair: Improve fairness between cfs tasks Vincent Guittot
2020-09-21  7:24 ` [PATCH 1/4 v2] sched/fair: relax constraint on task's load during load balance Vincent Guittot
2020-09-23 14:43   ` Valentin Schneider
2020-09-29  7:56   ` [tip: sched/core] sched/fair: Relax " tip-bot2 for Vincent Guittot
2020-09-21  7:24 ` [PATCH 2/4 v2] sched/fair: reduce minimal imbalance threshold Vincent Guittot
2020-09-23 14:43   ` Valentin Schneider
2020-09-29  7:56   ` [tip: sched/core] sched/fair: Reduce " tip-bot2 for Vincent Guittot
2020-09-21  7:24 ` [PATCH 3/4 v2] sched/fair: minimize concurrent LBs between domain level Vincent Guittot
2020-09-23 14:43   ` Valentin Schneider
2020-09-29  7:56   ` [tip: sched/core] sched/fair: Minimize " tip-bot2 for Vincent Guittot
2020-09-21  7:24 ` [PATCH 4/4 v2] sched/fair: reduce busy load balance interval Vincent Guittot
2020-09-23 14:43   ` Valentin Schneider
2020-09-29  7:56   ` tip-bot2 for Vincent Guittot [this message]
2020-09-23 15:47 ` [PATCH 0/4 v2] sched/fair: Improve fairness between cfs tasks Mel Gorman

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