LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Barry Song <21cnbao@gmail.com>
To: aubrey.li@linux.intel.com
Cc: linux-kernel@vger.kernel.org, mgorman@techsingularity.net,
	mingo@kernel.org, peterz@infradead.org,
	song.bao.hua@hisilicon.com, valentin.schneider@arm.com,
	vincent.guittot@linaro.org, yangyicong@huawei.com
Subject: Re: [PATCH 8/9] sched/fair: select idle cpu from idle cpumask for task wakeup
Date: Fri, 17 Sep 2021 12:15:39 +0800	[thread overview]
Message-ID: <20210917041539.7862-1-21cnbao@gmail.com> (raw)
In-Reply-To: <125eb98a-241b-078f-1844-b0521425ed1e@linux.intel.com>

> @@ -4965,6 +4965,7 @@ void scheduler_tick(void)
>
>  #ifdef CONFIG_SMP
> 	rq->idle_balance = idle_cpu(cpu);
> +	update_idle_cpumask(cpu, rq->idle_balance);
>  	trigger_load_balance(rq);
>  #endif
> }

might be stupid, a question bothering yicong and me is that why don't we
choose to update_idle_cpumask() while idle task exits and switches to a
normal task?
for example, before tick comes, cpu has exited from idle, but we are only
able to update it in tick. this makes idle_cpus_span inaccurate, thus we
will scan cpu which isn't actually idle in select_idle_sibling.
is it because of the huge update overhead?

Thanks
barry

  parent reply	other threads:[~2021-09-17  4:15 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 10:22 [RFC PATCH 0/9] Modify and/or delete SIS_PROP Mel Gorman
2021-07-26 10:22 ` [PATCH 1/9] sched/fair: Track efficiency of select_idle_sibling Mel Gorman
2021-07-26 10:22 ` [PATCH 2/9] sched/fair: Track efficiency of task recent_used_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 3/9] sched/fair: Track efficiency of select_idle_core Mel Gorman
2021-07-26 10:22 ` [PATCH 4/9] sched/fair: Use prev instead of new target as recent_used_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 5/9] sched/fair: Avoid a second scan of target in select_idle_cpu Mel Gorman
2021-07-26 10:22 ` [PATCH 6/9] sched/fair: Make select_idle_cpu() proportional to cores Mel Gorman
2021-07-26 10:22 ` [PATCH 7/9] sched/fair: Enforce proportional scan limits when scanning for an idle core Mel Gorman
2021-08-02 10:52   ` Song Bao Hua (Barry Song)
2021-08-04 10:22     ` Mel Gorman
2021-07-26 10:22 ` [PATCH 8/9] sched/fair: select idle cpu from idle cpumask for task wakeup Mel Gorman
2021-08-02 10:41   ` Song Bao Hua (Barry Song)
2021-08-04 10:26     ` Mel Gorman
2021-08-05  0:23       ` Aubrey Li
2021-09-17  3:44         ` Barry Song
2021-09-17  4:15         ` Barry Song [this message]
2021-09-17  9:11           ` Aubrey Li
2021-09-17 13:35             ` Mel Gorman
2021-07-26 10:22 ` [PATCH 9/9] sched/core: Delete SIS_PROP and rely on the idle cpu mask 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=20210917041539.7862-1-21cnbao@gmail.com \
    --to=21cnbao@gmail.com \
    --cc=aubrey.li@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@techsingularity.net \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=song.bao.hua@hisilicon.com \
    --cc=valentin.schneider@arm.com \
    --cc=vincent.guittot@linaro.org \
    --cc=yangyicong@huawei.com \
    --subject='Re: [PATCH 8/9] sched/fair: select idle cpu from idle cpumask for task wakeup' \
    /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

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).