From: Juri Lelli <juri.lelli@redhat.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
linux-kernel@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Quentin Perret <qperret@google.com>,
Valentin Schneider <valentin.schneider@arm.com>
Subject: Re: [PATCH] sched/deadline: Reduce rq lock contention in dl_add_task_root_domain()
Date: Thu, 21 Jan 2021 07:28:19 +0100 [thread overview]
Message-ID: <20210121062819.GH10569@localhost.localdomain> (raw)
In-Reply-To: <20210119083542.19856-1-dietmar.eggemann@arm.com>
Hi,
On 19/01/21 09:35, Dietmar Eggemann wrote:
> dl_add_task_root_domain() is called during sched domain rebuild:
>
> rebuild_sched_domains_locked()
> partition_and_rebuild_sched_domains()
> rebuild_root_domains()
> for all top_cpuset descendants:
> update_tasks_root_domain()
> for all tasks of cpuset:
> dl_add_task_root_domain()
>
> Change it so that only the task pi lock is taken to check if the task
> has a SCHED_DEADLINE (DL) policy. In case that p is a DL task take the
> rq lock as well to be able to safely de-reference root domain's DL
> bandwidth structure.
>
> Most of the tasks will have another policy (namely SCHED_NORMAL) and
> can now bail without taking the rq lock.
>
> One thing to note here: Even in case that there aren't any DL user
> tasks, a slow frequency switching system with cpufreq gov schedutil has
> a DL task (sugov) per frequency domain running which participates in DL
> bandwidth management.
>
> Reviewed-by: Quentin Perret <qperret@google.com>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Looks good to me, thanks!
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Best,
Juri
next prev parent reply other threads:[~2021-01-21 6:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-19 8:35 [PATCH] sched/deadline: Reduce rq lock contention in dl_add_task_root_domain() Dietmar Eggemann
2021-01-19 20:51 ` Valentin Schneider
2021-01-20 7:52 ` Daniel Bristot de Oliveira
2021-01-21 6:28 ` Juri Lelli [this message]
2021-02-08 13:43 ` Peter Zijlstra
2021-02-10 13:53 ` [tip: sched/core] " tip-bot2 for Dietmar Eggemann
2021-02-17 13:17 ` tip-bot2 for Dietmar Eggemann
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=20210121062819.GH10569@localhost.localdomain \
--to=juri.lelli@redhat.com \
--cc=bristot@redhat.com \
--cc=dietmar.eggemann@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=qperret@google.com \
--cc=rostedt@goodmis.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;
as well as URLs for NNTP newsgroup(s).