From: David Laight <David.Laight@ACULAB.COM>
To: 'Qais Yousef' <qais.yousef@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>
Cc: 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: Scheduling tasks on idle cpu
Date: Mon, 11 Apr 2022 08:26:33 +0000 [thread overview]
Message-ID: <030aacb0c1304e43ab917924dcf4f138@AcuMS.aculab.com> (raw)
From: Qais Yousef
> Sent: 09 April 2022 18:09
...
> RT scheduler will push/pull tasks to ensure the task will get to run ASAP if
> there's another cpu at lower priority is available
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.
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.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next reply other threads:[~2022-04-11 8:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 8:26 David Laight [this message]
2022-04-11 9:26 ` Scheduling tasks on idle cpu 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
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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