linux-kernel - Re: [RFC PATCH 2/2] sched/eevdf: Introduce a cgroup interface for slice

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Message-ID: <Zx_LwYshJV5LERm9@slm.duckdns.org>
Date: Mon, 28 Oct 2024 07:37:05 -1000
From: Tejun Heo <tj@...nel.org>
To: Tianchen Ding <dtcccc@...ux.alibaba.com>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>
Subject: Re: [RFC PATCH 2/2] sched/eevdf: Introduce a cgroup interface for
 slice

Hello,

On Mon, Oct 28, 2024 at 02:33:13PM +0800, Tianchen Ding wrote:
> Introduce "cpu.fair_slice" for cgroup v2 and "cpu.fair_slice_us" for v1
> according to their name styles. The unit is always microseconds.
> 
> A cgroup with shorter slice can preempt others more easily. This could be
> useful in container scenarios.
> 
> By default, cpu.fair_slice is 0, which means the slice of se is
> calculated by min_slice from its cfs_rq. If cpu.fair_slice is set, it
> will overwrite se->slice with the customized value.

Provided that this tunable is necessary, wouldn't it be more useful to
figure out what per-task interface would look like first? Maybe there are
cases where per-cgroup slice config makes sense but that sounds
significantly less useful than being able to configure it per-task.

Thanks.

-- 
tejun