linux-kernel - Re: [PATCH 1/1] sched: Consider CPU contention in frequency & load-balance busiest CPU selection

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Date:   Fri, 5 May 2023 20:02:36 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Qais Yousef <qyousef@...alina.io>,
        Kajetan Puchalski <kajetan.puchalski@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Vincent Donnefort <vdonnefort@...gle.com>,
        Quentin Perret <qperret@...gle.com>,
        Abhijeet Dharmapurikar <adharmap@...cinc.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] sched: Consider CPU contention in frequency &
 load-balance busiest CPU selection

Hi Chenyu,

On 05/05/2023 09:10, Chen Yu wrote:
> On 2023-04-06 at 17:50:30 +0200, Dietmar Eggemann wrote:
>> Use new cpu_boosted_util_cfs() instead of cpu_util_cfs().
>>
>> The former returns max(util_avg, runnable_avg) capped by max CPU
>> capacity. CPU contention is thereby considered through runnable_avg.
>>
>> The change in load-balance only affects migration type `migrate_util`.
>>
>> Suggested-by: Vincent Guittot <vincent.guittot@...aro.org>
>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
>>
> Tested on Intel Sapphire Rapids which has 2x56C/112T = 224 CPUs.
> The test tries to check if this is any impact on find_busiest_queue()
> so it was tested with cpufreq governor performance.
> The baseline is the 6.3 sched/core branch on top of
> Commit 67fff302fc445a ("sched/fair: Introduce SIS_CURRENT to wake up"),
> and compared to the code with current patch applied.
> 
> In summary no obvious difference and some small improvements on tbench
> were observed so far:

many thanks for the test results!

Could you share the parameter lists you use for the individual tests?
This would make it easier to understand the results and rerun the tests
on similar machines.

[...]