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From: Chengming Zhou <zhouchengming@bytedance.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, rostedt@goodmis.org,
	dietmar.eggemann@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [External] Re: [PATCH] psi: Remove the redundant psi_task_tick
Date: Tue, 9 Feb 2021 10:21:22 +0800	[thread overview]
Message-ID: <1165c0f2-134e-932d-e427-3b65c659108d@bytedance.com> (raw)
In-Reply-To: <YCFqxEw0wJC6UGiE@cmpxchg.org>

在 2021/2/9 上午12:45, Johannes Weiner 写道:

> On Sun, Feb 07, 2021 at 07:56:42PM +0800, Chengming Zhou wrote:
>> From: zhouchengming <zhouchengming@bytedance.com>
>>
>> When the current task in a cgroup is in_memstall, the corresponding psi_group
>> is in PSI_MEM_FULL state
> This is correct.
>
>> so we can remove the redundant psi_task_tick from scheduler_tick to
>> save this periodic cost.
> But this isn't. It IS the task tick that makes it so. The state change
> tracking counts MEMSTALL tasks and ONCPU tasks, but it doesn't check
> whether the ONCPU task is the MEMSTALL one.

Yes, you are right, I messed them up... will take a closer look at the code later.

Thanks.

> It would be possible to incorporate that into psi_task_switch(), but
> you have to be careful with the branches because that path is often
> hotter than the timer tick.
>
> This patch by itself breaks page reclaim detection, so NAK.

      reply	other threads:[~2021-02-09  2:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07 11:56 Chengming Zhou
2021-02-08 16:45 ` Johannes Weiner
2021-02-09  2:21   ` Chengming Zhou [this message]

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