linux-kernel - Re: [PATCH v2] sched/uclamp: Align uclamp and util

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Message-ID: <837ee35a-ffa4-4ed7-a1c4-be97db3087f8@arm.com>
Date: Tue, 1 Apr 2025 10:32:03 +0200
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Xuewen Yan <xuewen.yan@...soc.com>, mingo@...hat.com,
 peterz@...radead.org, juri.lelli@...hat.com, vincent.guittot@...aro.org
Cc: rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
 vschneid@...hat.com, hongyan.xia2@....com, qyousef@...alina.io,
 ke.wang@...soc.com, di.shen@...soc.com, linux-kernel@...r.kernel.org,
 xuewen.yan94@...il.com
Subject: Re: [PATCH v2] sched/uclamp: Align uclamp and util_est and call
 before freq update

On 25/03/2025 02:47, Xuewen Yan wrote:
> When task's uclamp is set, we hope that the CPU frequency
> can increase as quickly as possible when the task is enqueued.
> Because the cpu frequency updating happens during the enqueue_task(),
> so the rq's uclamp needs to be updated before the task is enqueued,
> just like util_est.
> So, aline the uclamp and util_est and call before freq update.
> 
> For sched-delayed tasks, the rq uclamp/util_est should only be updated
> when they are enqueued upon being awakened.
> So simply the logic of util_est's enqueue/dequeue check.
> 
> Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>
> ---
> v2:
> - simply the util-est's en/dequeue check;
> ---
> Previous discussion:
> https://lore.kernel.org/all/CAB8ipk8pEvOtCm-d0o1rsekwxPWUHk9iBGtt9TLTWW-iWTQKiA@mail.gmail.com/
> https://lore.kernel.org/all/84441660bef0a5e67fd09dc3787178d0276dad31.1740664400.git.hongyan.xia2@arm.com/T/#u
> https://lore.kernel.org/all/CAB8ipk9LpbiUDnbcV6+59+Sa=Ai7tFzO===mpLD3obNdV4=J-A@mail.gmail.com/T/#u
> https://lore.kernel.org/all/aa8baf67-a8ec-4ad8-a6a8-afdcd7036771@arm.com/

LGTM.

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>