From: Steven Rostedt <rostedt@goodmis.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Qais Yousef' <qais.yousef@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
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>,
"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: Mon, 11 Apr 2022 05:26:41 -0400 [thread overview]
Message-ID: <20220411052641.5370437f@rorschach.local.home> (raw)
In-Reply-To: <030aacb0c1304e43ab917924dcf4f138@AcuMS.aculab.com>
On Mon, 11 Apr 2022 08:26:33 +0000
David Laight <David.Laight@ACULAB.COM> wrote:
> Does that actually happen?
> I've seen the following:
> 34533 [017]: sys_futex(uaddr: 1049104, op: 85, val: 1, utime: 1, uaddr2: 1049100, val3: 4000001)
> 34533 [017]: sched_migrate_task: pid=34512 prio=120 orig_cpu=14 dest_cpu=17
> 34533 [017]: sched_wakeup: pid=34512 prio=120 success=1 target_cpu=017
> and pid 34512 doesn't get scheduled until pid 34533 finally sleeps.
> This is in spite of there being 5 idle cpu.
What's the topology? I believe the scheduler will refrain from
migrating tasks to idle CPUs that are on other NUMA nodes as much as
possible. Were those other 5 idle CPUs on another node?
-- Steve
> cpu 14 is busy running a RT thread, but migrating to cpu 17 seems wrong.
>
> This is on a RHEL7 kernel, I've not replicated it on anything recent.
> But I've very much like a RT thread to be able to schedule a non-RT
> thread to run on an idle cpu.
next prev parent reply other threads:[~2022-04-11 9:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 8:26 David Laight
2022-04-11 9:26 ` Steven Rostedt [this message]
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
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
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