From: Mel Gorman <mgorman@techsingularity.net>
To: Hillf Danton <hdanton@sina.com>
Cc: Juri Lelli <juri.lelli@redhat.com>,
Barry Song <song.bao.hua@hisilicon.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Peter Ziljstra <peterz@infradead.org>,
Aubrey Li <aubrey.li@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Linux-ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 3/4] sched/fair: Do not replace recent_used_cpu with the new target
Date: Fri, 11 Dec 2020 09:45:40 +0000 [thread overview]
Message-ID: <20201211094540.GV3371@techsingularity.net> (raw)
In-Reply-To: <20201211093443.3259-1-hdanton@sina.com>
On Fri, Dec 11, 2020 at 05:34:43PM +0800, Hillf Danton wrote:
> On Fri, 11 Dec 2020 09:02:28 +0000 Mel Gorman wrote:
> >On Fri, Dec 11, 2020 at 02:25:42PM +0800, Hillf Danton wrote:
> >> On Tue, 8 Dec 2020 15:35:00 +0000 Mel Gorman wrote:
> >> > @@ -6277,17 +6277,13 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
> >> >
> >> > /* Check a recently used CPU as a potential idle candidate: */
> >> > recent_used_cpu = p->recent_used_cpu;
> >> > + p->recent_used_cpu = prev;
> >> > if (recent_used_cpu != prev &&
> >> > recent_used_cpu != target &&
> >> > cpus_share_cache(recent_used_cpu, target) &&
> >> > (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
> >> > cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) &&
> >>
> >> Typo? Fix it in spin if so.
> >>
> >
> >What typo?
>
> After your change it is prev that we check against p->cpus_ptr instead of
> the recent CPU. Wonder the point to do such a check for returning the
> recent one.
Ah... yes, this is indeed wrong. It wouldn't affect Vincent's case
that showed a problem with a hackbench configuration (which I'm still
disappointed about as it's a trade-off depending on machine and workload)
but it allows a task to run on the wrong cpu if sched_setscheduler()
was called between wakeup events.
--
Mel Gorman
SUSE Labs
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-12-11 9:47 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 15:34 [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-08 15:34 ` [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2020-12-08 16:13 ` Vincent Guittot
2020-12-08 15:34 ` [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
2020-12-08 16:03 ` Vincent Guittot
2020-12-08 16:30 ` Mel Gorman
2020-12-09 5:28 ` Li, Aubrey
2020-12-09 9:05 ` Mel Gorman
2020-12-09 11:07 ` Li, Aubrey
2020-12-09 11:33 ` Mel Gorman
2020-12-10 5:18 ` Li, Aubrey
2020-12-10 9:32 ` Mel Gorman
2020-12-08 15:35 ` [PATCH 3/4] sched/fair: Do not replace recent_used_cpu with the new target Mel Gorman
2020-12-08 16:14 ` Vincent Guittot
2020-12-10 9:40 ` Vincent Guittot
2020-12-11 6:25 ` Hillf Danton
2020-12-11 9:02 ` Mel Gorman
2020-12-11 9:34 ` Hillf Danton
2020-12-11 9:45 ` Mel Gorman [this message]
2020-12-08 15:35 ` [PATCH 4/4] sched/fair: Return an idle cpu if one is found after a failed search for an idle core Mel Gorman
2020-12-08 16:15 ` Vincent Guittot
2020-12-09 14:37 ` [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling Mel Gorman
2020-12-10 8:00 ` Vincent Guittot
2020-12-10 9:38 ` Vincent Guittot
2020-12-10 11:04 ` Mel Gorman
2020-12-11 9:51 ` Vincent Guittot
2020-12-11 10:23 ` Mel Gorman
2020-12-12 10:02 ` Vincent Guittot
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=20201211094540.GV3371@techsingularity.net \
--to=mgorman@techsingularity.net \
--cc=aubrey.li@linux.intel.com \
--cc=hdanton@sina.com \
--cc=juri.lelli@redhat.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=song.bao.hua@hisilicon.com \
--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).