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From: Valentin Schneider <valentin.schneider@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Yafang Shao <laoar.shao@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched, fair: try to prevent migration thread from preempting non-cfs task
Date: Tue, 15 Jun 2021 17:39:52 +0100	[thread overview]
Message-ID: <87im2faxpj.mognet@arm.com> (raw)
In-Reply-To: <CAKfTPtDj6E00o4ZFDJ+kJKqy8J3oLm-mVSajUnHpufFCRiX_8g@mail.gmail.com>

On 15/06/21 17:45, Vincent Guittot wrote:
> On Tue, 15 Jun 2021 at 16:55, Valentin Schneider
> <valentin.schneider@arm.com> wrote:
>> This can be summarized as in the below, no?
>>
>>                         /*
>>                          * Don't cause a higher-than-CFS task to be preempted by
>>                          * the CPU stopper.
>>                          */
>
> IMO, it's worth keeping the explanation that we are there because:
> - a CFS task that was running during the 1st step :  if
> (busiest->nr_running > 1) { ...
> so we didn't pull the task
> - but it has been preempted while lb was deciding if it needs an
> active load balance
>
> so maybe something like:
>                          /*
>                           * Don't kick the active_load_balance_cpu_stop,
>                           * if the CFS task has been preempted by higher
>                           * priority task in the meantime.
>                          */
>

Ack

  reply	other threads:[~2021-06-15 16:40 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 12:15 [PATCH] sched, fair: try to prevent migration thread from preempting non-cfs task Yafang Shao
2021-06-15 14:55 ` Valentin Schneider
2021-06-15 15:45   ` Vincent Guittot
2021-06-15 16:39     ` Valentin Schneider [this message]
2021-06-15 20:35 ` Peter Zijlstra
2021-06-16  1:44   ` Yafang Shao
2021-06-16  7:15     ` Peter Zijlstra
2021-06-16  7:29       ` Vincent Guittot
2021-06-16  8:29         ` Peter Zijlstra
2021-06-16  9:49           ` Yafang Shao
2021-06-16  9:45       ` Yafang Shao

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