linux-kernel - Re: [PATCH] cpufreq: schedutil: Don't consider freq reduction to busy CPU if need_freq

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Message-ID: <20210219144140.00004de9.zbestahu@gmail.com>
Date:   Fri, 19 Feb 2021 14:41:40 +0800
From:   Yue Hu <zbestahu@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     rjw@...ysocki.net, mingo@...hat.com, peterz@...radead.org,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        huyue2@...ong.com, zbestahu@....com
Subject: Re: [PATCH] cpufreq: schedutil: Don't consider freq reduction to
 busy CPU if need_freq_update is set

On Fri, 19 Feb 2021 09:39:33 +0530
Viresh Kumar <viresh.kumar@...aro.org> wrote:

> On 19-02-21, 11:38, Yue Hu wrote:
> > There's a possibility: we will use the previous freq to update if
> > next_f is reduced for busy CPU if need_freq_update is set in
> > sugov_update_next_freq().  
> 
> Right.
> 
> > This possibility would happen now? And this
> > update is what we want if it happens?  
> 
> This is exactly what we want here, don't reduce speed for busy CPU,

I understand it should not skip this update but set the same freq as
previous one again for the specail case if need_freq_update is set. Am
i rt?

> but we also need to make sure we are in the policy's valid range
> which cpufreq core will take care of.
> 
> > This is related to another possible patch ready to send.  
> 
> I am not sure what's there to send now.

I will send later after figure out the doubt above.

>