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Date:   Fri, 19 Feb 2021 13:12:49 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Yue Hu <zbestahu@gmail.com>
Cc:     rjw@rjwysocki.net, mingo@redhat.com, peterz@infradead.org,
        juri.lelli@redhat.com, vincent.guittot@linaro.org,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        huyue2@yulong.com, zbestahu@163.com
Subject: Re: [PATCH] cpufreq: schedutil: Don't consider freq reduction to
 busy CPU if need_freq_update is set
Message-ID: <20210219074249.2hcwcnakihor343h@vireshk-i7>
References: <20210218082514.1437-1-zbestahu@gmail.com>
 <20210218102029.syj6vkltlbtoxsig@vireshk-i7>
 <20210219113804.00004a7e.zbestahu@gmail.com>
 <20210219040933.2o5hhbjb6emf3xl4@vireshk-i7>
 <20210219144140.00004de9.zbestahu@gmail.com>
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On 19-02-21, 14:41, Yue Hu wrote:
> On Fri, 19 Feb 2021 09:39:33 +0530
> Viresh Kumar <viresh.kumar@linaro.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 special case if need_freq_update is set. Am
> i rt?

The special check, about not reducing freq if CPU had been busy
recently, doesn't have anything to do with need_freq_update.

Though previously we added the need_freq_update check there to make
sure we account for any recent policy min/max change and don't skip
freq update anymore. That won't happen anymore and so we don't need
any check here related to need_freq_update.

If you still have doubt, please explain your concern in detail with an
example as I am failing to understand it.

-- 
viresh