linux-kernel - Re: [PATCH v1] sched/uclamp: Exclude kernel threads from uclamp logic

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Message-ID: <20250703105147.13e10a77@batman.local.home>
Date: Thu, 3 Jul 2025 10:51:47 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Zihuan Zhang <zhangzihuan@...inos.cn>
Cc: Christian Loehle <christian.loehle@....com>, xuewen.yan@...soc.com,
 vincent.guittot@...aro.org, mingo@...hat.com, peterz@...radead.org,
 juri.lelli@...hat.com, bsegall@...gle.com, mgorman@...e.de,
 vschneid@...hat.com, hongyan.xia2@....com, linux-kernel@...r.kernel.org,
 ke.wang@...soc.com, di.shen@...soc.com, xuewen.yan94@...il.com,
 kprateek.nayak@....com, kuyo.chang@...iatek.com, juju.sung@...iatek.com,
 qyousef@...alina.io
Subject: Re: [PATCH v1] sched/uclamp: Exclude kernel threads from uclamp
 logic

On Thu, 3 Jul 2025 18:07:20 +0800
Zihuan Zhang <zhangzihuan@...inos.cn> wrote:

> As Xuewen mentioned, some kernel threads may intentionally set 
> scheduling attributes for performance. So instead of unconditionally 
> excluding all kernel threads, I’m now considering a more conservative 
> approach:
> skip only those kthreads that haven’t explicitly set any clamp values.

The above comment bothers me. What kernel threads set scheduling attributes?

From my experience working on real-time, no kernel thread gets
scheduling tweaking correct.

-- Steve