linux-kernel - Re: [PATCH] sched/cgroup: Lock optimize for cgroup cpu throttle

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Message-ID: <20250819130656.DdJqAScZ@linutronix.de>
Date: Tue, 19 Aug 2025 15:06:56 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Xin Zhao <jackzxcui1989@....com>
Cc: tj@...nel.org, hannes@...xchg.org, mkoutny@...e.com, mingo@...hat.com,
	peterz@...radead.org, juri.lelli@...hat.com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	vschneid@...hat.com, will@...nel.org, boqun.feng@...il.com,
	longman@...hat.com, clrkwllms@...nel.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev
Subject: Re: [PATCH] sched/cgroup: Lock optimize for cgroup cpu throttle

On 2025-08-11 23:13:16 [+0800], Xin Zhao wrote:
> Dear Sebastian,
> 
> I believe what you mentioned is related to the same issue that Valentin
> brought up later, which is the current solution of "delaying CPU throttling
> through the task_work mechanism until returning to user mode."
> My colleagues and I indeed noticed this from the beginning. However, on our
> 6.1.134 RT-Linux system, we have tried new versions of this solution one by
> one, but they have all failed during basic script tests, so none have reached
> the stage of being used in our project. I see that this modification has been
> promoted in the community for more than two years, yet it remains in a state
> that doesn't work well (on our 6.1.134 RT-Linux system). I wonder if the
> changes require too many considerations or if this modification simply isn't
> suitable for running on RT-Linux. Our project cannot afford to wait, and
> there are many performance issues in RT-Linux.

You are free to use the patch.
Based on your description I assume that the patch Valentin referenced
will solve your problem. If not, it will be interesting to know why it
is not working. Otherwise you keep maintaining your patch.

> Thanks
> Xin Zhao

Sebastian