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

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Message-Id: <20250811160454.884224-1-jackzxcui1989@163.com>
Date: Tue, 12 Aug 2025 00:04:54 +0800
From: Xin Zhao <jackzxcui1989@....com>
To: tj@...nel.org,
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Cc: cgroups@...r.kernel.org,
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Subject: Re: [PATCH] sched/cgroup: Lock optimize for cgroup cpu throttle

On Mon, 2025-08-11 at 22:18 +0800, Sebastian wrote:

> Yeah, please have a look at:
> https://lore.kernel.org/lkml/20250715071658.267-1-ziqianlu@bytedance.com/

Dear Valentin,

In addition to the information in my previous response to Sebastian, I would
like to add the following point as a reason for my self-recommendation (to
explore my patch for solving the cgroup performance issue in RT-Linux):
RT-Linux is a system that places a high emphasis on real-time performance.
The fact that regular tasks are also included in cgroup groups and throttled
suggests that they are relatively low-priority tasks that are not expected to
interfere with high-priority tasks. Therefore, is it not a bit too late to
impose limits only after returning to user mode? Furthermore, when a throttled
task is awakened from S or D state, according to the logic of "imposing limits
after returning to user mode," it could cause that low-priority task to wake
up associated low-priority tasks one after another, leading to a sudden
increase in running time, which contradicts the relatively precise CPU usage
targets typically required in RT-Linux systems.
Additionally, I believe there are still many areas for improvement in my patch,
and I hope to bring it to the community to gather suggestions from experts to
see if there are areas for iterative improvement.

Thanks
Xin Zhao