All of lore.kernel.org
 help / color / mirror / Atom feed
From: Vincent Guittot <vincent.guittot@linaro.org>
To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de,
	linux-kernel@vger.kernel.org
Cc: valentin.schneider@arm.com, pauld@redhat.com, hdanton@sina.com,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH 4/4 v2] sched/fair: reduce busy load balance interval
Date: Mon, 21 Sep 2020 09:24:24 +0200	[thread overview]
Message-ID: <20200921072424.14813-5-vincent.guittot@linaro.org> (raw)
In-Reply-To: <20200921072424.14813-1-vincent.guittot@linaro.org>

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.

Reviewed-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Vincent Guittot <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 41df62884cea..a3a2417fec54 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,
-- 
2.17.1


  parent reply	other threads:[~2020-09-21  7:24 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 ` Vincent Guittot [this message]
2020-09-23 14:43   ` [PATCH 4/4 v2] sched/fair: reduce busy load balance interval Valentin Schneider
2020-09-29  7:56   ` [tip: sched/core] sched/fair: Reduce " tip-bot2 for Vincent Guittot
2020-09-23 15:47 ` [PATCH 0/4 v2] sched/fair: Improve fairness between cfs tasks Mel Gorman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200921072424.14813-5-vincent.guittot@linaro.org \
    --to=vincent.guittot@linaro.org \
    --cc=bsegall@google.com \
    --cc=dietmar.eggemann@arm.com \
    --cc=hdanton@sina.com \
    --cc=juri.lelli@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@suse.de \
    --cc=mingo@redhat.com \
    --cc=pauld@redhat.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=valentin.schneider@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.