From: David Laight <David.Laight@ACULAB.COM>
To: 'Vincent Guittot' <vincent.guittot@linaro.org>
Cc: Qais Yousef <qais.yousef@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"bsegall@google.com" <bsegall@google.com>,
"mgorman@suse.de" <mgorman@suse.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"parth@linux.ibm.com" <parth@linux.ibm.com>,
"chris.hyser@oracle.com" <chris.hyser@oracle.com>,
"pkondeti@codeaurora.org" <pkondeti@codeaurora.org>,
"Valentin.Schneider@arm.com" <Valentin.Schneider@arm.com>,
"patrick.bellasi@matbug.net" <patrick.bellasi@matbug.net>,
"pjt@google.com" <pjt@google.com>, "pavel@ucw.cz" <pavel@ucw.cz>,
"tj@kernel.org" <tj@kernel.org>,
"qperret@google.com" <qperret@google.com>,
"tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>,
Wei Wang <wvw@google.com>
Subject: RE: Scheduling tasks on idle cpu
Date: Thu, 14 Apr 2022 14:14:22 +0000 [thread overview]
Message-ID: <5fc162f60ba84ab3a61992084d76c726@AcuMS.aculab.com> (raw)
In-Reply-To: <CAKfTPtB0EniWa_Wqx9596Zm5ZyoB3CRWwkgcYgxYB=318eWsWQ@mail.gmail.com>
From: Vincent Guittot
> Sent: 14 April 2022 11:17
...
> > > David can rerun is use case after disabling sched_feat(SIS_PROP)
> >
> > How would I do that?
>
> echo NO_SIS_PROP > /sys/kernel/debug/sched/features
That may not be in the kernel I'm using.
# cat /sys/kernel/debug/sched_features
GENTLE_FAIR_SLEEPERS START_DEBIT NO_NEXT_BUDDY LAST_BUDDY CACHE_HOT_BUDDY WAKEUP_PREEMPTION ARCH_POWER NO_HRTICK NO_DOUBLE_TICK LB_BIAS NONTASK_POWER TTWU_QUEUE RT_RUNTIME_SHARE NO_LB_MIN NUMA NUMA_FAVOUR_HIGHER NO_NUMA_RESIST_LOWER
I've been looking at another ftrace output.
The scheduler does like migrating the process to the current cpu.
I have seen it migrate from one idle cpu to another idle cpu.
I've not seen it migrate from an idle cpu to the current cpu.
(But I've not looked hard.)
These are all the migrates:
TiNG task:12-1005 [026] d... 1111081.796560: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=11 dest_cpu=16
TiNG task:31-1026 [005] d... 1111081.836556: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=16 dest_cpu=11
TiNG task:28-1023 [033] d... 1111081.856589: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=11 dest_cpu=33
TiNG task:11-1004 [013] d... 1111081.856606: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=33 dest_cpu=13
TiNG task:19-1012 [002] d... 1111081.896564: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=13 dest_cpu=10
TiNG task:26-1019 [008] d... 1111081.956551: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=10 dest_cpu=18
TiNG task:34-1029 [001] d... 1111082.016527: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=18 dest_cpu=1
TiNG task:20-1013 [021] d... 1111082.016589: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=1 dest_cpu=21
TiNG task:32-1027 [000] d... 1111082.036455: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=21 dest_cpu=2
TiNG task:15-1008 [006] d... 1111082.056539: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=2 dest_cpu=14
TiNG task:34-1029 [001] d... 1111082.076536: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=14 dest_cpu=1
TiNG task:21-1014 [004] d... 1111082.076589: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=1 dest_cpu=4
TiNG task:11-1004 [013] d... 1111082.096526: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=4 dest_cpu=13
TiNG task:28-1023 [033] d... 1111082.096584: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=13 dest_cpu=33
TiNG task:25-1018 [029] d... 1111082.116549: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=33 dest_cpu=11
TiNG task:27-1020 [032] d... 1111082.176519: sched_migrate_task: comm=RTP sockets pid=990 prio=120 orig_cpu=11 dest_cpu=16
There are a couple of places where there 2 wakeups before the schedule.
The scheduler definitely doesn't like waking up a process on an even cpu from on odd one.
But there are also the 13->33 and 1->21 ones.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-04-14 15:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 8:26 Scheduling tasks on idle cpu David Laight
2022-04-11 9:26 ` Steven Rostedt
2022-04-11 9:57 ` David Laight
2022-04-11 23:34 ` Qais Yousef
2022-04-12 8:39 ` David Laight
2022-04-12 9:07 ` Vincent Guittot
2022-04-13 23:57 ` Qais Yousef
2022-04-14 7:54 ` Vincent Guittot
2022-04-14 8:35 ` David Laight
2022-04-14 10:16 ` Vincent Guittot
2022-04-14 14:14 ` David Laight [this message]
2022-04-15 7:15 ` Vincent Guittot
2022-04-13 23:51 ` Qais Yousef
2022-04-14 6:09 ` David Laight
2022-04-14 22:26 ` Qais Yousef
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=5fc162f60ba84ab3a61992084d76c726@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=Valentin.Schneider@arm.com \
--cc=bsegall@google.com \
--cc=chris.hyser@oracle.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=parth@linux.ibm.com \
--cc=patrick.bellasi@matbug.net \
--cc=pavel@ucw.cz \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=pkondeti@codeaurora.org \
--cc=qais.yousef@arm.com \
--cc=qperret@google.com \
--cc=rostedt@goodmis.org \
--cc=tim.c.chen@linux.intel.com \
--cc=tj@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=wvw@google.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 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).