From: Mel Gorman <mgorman@techsingularity.net>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
"Li, Aubrey" <aubrey.li@linux.intel.com>,
Valentin Schneider <valentin.schneider@arm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle
Date: Mon, 30 Nov 2020 14:40:20 +0000 [thread overview]
Message-ID: <20201130144020.GS3371@techsingularity.net> (raw)
The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
kernel/sched/fair.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0d54d69ba1a5..d9acd55d309b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6087,10 +6087,11 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
break;
}
}
- cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
if (idle)
return core;
+
+ cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
}
/*
next reply other threads:[~2020-11-30 14:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 14:40 Mel Gorman [this message]
2020-11-30 14:47 ` [PATCH] sched/fair: Clear SMT siblings after determining the core is not idle Vincent Guittot
2020-12-01 1:04 ` Li, Aubrey
2020-12-01 11:03 ` Peter Zijlstra
2020-12-03 9:13 ` [tip: sched/core] " tip-bot2 for Mel Gorman
2020-12-11 9:34 ` tip-bot2 for 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=20201130144020.GS3371@techsingularity.net \
--to=mgorman@techsingularity.net \
--cc=aubrey.li@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=valentin.schneider@arm.com \
--cc=vincent.guittot@linaro.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox