linux-kernel - Re: [RFC PATCH 5/6] sched/uclamp: Remove all uclamp bucket logic

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Message-ID: <ea323a83-fa26-4500-8456-987bb70c3e4d@arm.com>
Date:   Fri, 3 Nov 2023 14:01:38 +0000
From:   Hongyan Xia <hongyan.xia2@....com>
To:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Juri Lelli <juri.lelli@...hat.com>
Cc:     Qais Yousef <qyousef@...alina.io>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Lukasz Luba <lukasz.luba@....com>,
        Christian Loehle <christian.loehle@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 5/6] sched/uclamp: Remove all uclamp bucket logic

On 03/11/2023 13:50, Dietmar Eggemann wrote:
> On 04/10/2023 11:04, Hongyan Xia wrote:
>> From: Hongyan Xia <hongyan.xia2@....com>
>>
>> Also rewrite uclamp_update_active() so that the effective uclamp values
>> are updated every time we change task group properties, change system
>> defaults or a request is issued from userspace.
> 
> Tested it with
> 
> # cgcreate -g cpu:/A
> # echo $$ > /sys/fs/cgroup/cpu/A/tasks
> 
> (1) per-task
> 
> # uclampset --pid $$  -m 256 -M 768
> 
> (2) per taskgroup
> 
> # echo 25.0 > /sys/fs/cgroup/cpu/A/cpu.uclamp.min
> # echo 75.0 > /sys/fs/cgroup/cpu/A/cpu.uclamp.max
> 
> (3) system-wide
> 
> # echo 256 > /proc/sys/kernel/sched_util_clamp_min
> # echo 768 > /proc/sys/kernel/sched_util_clamp_max
> 
> uclamp_update_active() -> uclamp_update_active_nolock() is called in all
> cases.
> 

Thanks for testing!

> 
> uclamp_eff_get()'s function header still mentions `clamp bucket index`.

This is indeed confusing. I have changed it from 'clamp bucket index' to 
just 'uclamp value'.

>> [...]
> 
> [...]