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From: chenying <chenying.kernel@bytedance.com>
To: Josh Don <joshdon@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Benjamin Segall <bsegall@google.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	duanxiongchun@bytedance.com, zhouchengming@bytedance.com,
	songmuchun@bytedance.com, zhengqi.arch@bytedance.com,
	zhoufeng.zf@bytedance.com, ligang.bdlg@bytedance.com
Subject: Re: [External] Re: Subject: [PATCH] sched/fair: prioritize normal task over sched_idle task with vruntime offset
Date: Tue, 15 Mar 2022 10:04:55 +0800	[thread overview]
Message-ID: <5de97c7f-2c71-34d0-9443-27f71960b4dd@bytedance.com> (raw)
In-Reply-To: <CABk29NsBEZ63eQ-avDBHe1LYj+wJNSTkCxPDQ=eTNS9_i9e0NA@mail.gmail.com>

在 2022/3/15 8:30, Josh Don 写道:
> On Sun, Mar 13, 2022 at 3:07 AM chenying <chenying.kernel@bytedance.com> wrote:
>>
>> If I set the sched_idle_vruntime_offset to a relatively small value
>> (e.g. 10 minutes), can this issues be avoided?
> 
> That's still long enough to cause lockups.
> 
> Is the issue that you have a large number of sched_idle entities, and
> the occasional latency sensitive thing that wakes up for a short
> duration? Have you considered approaching this from the other
> direction (ie. if we have a latency sensitive thing wake onto a cpu
> running only sched idle stuff, we could change entity placement to
> position the latency sensitive thing further left on the timeline,
> akin to !GENTLE_FAIR_SLEEPERS).

I think this may not guarantee that latency sensitive tasks are always 
to the left of idle tasks. And it may get complicated if a 
latency-sensitive task is woken up onto a cpu which there are already 
multiple latency-sensitive tasks and sched_idle tasks.

  reply	other threads:[~2022-03-15  2:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-11  7:58 chenying
2022-03-12 12:03 ` Peter Zijlstra
2022-03-13  5:37   ` [External] " chenying
2022-03-13  9:02     ` Peter Zijlstra
2022-03-13 10:06       ` chenying
2022-03-15  0:30         ` Josh Don
2022-03-15  2:04           ` chenying [this message]
2022-03-15  2:21             ` Josh Don

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