On Thu, 18 Feb 2021 15:50:29 +0530
Viresh Kumar <viresh.ku...@linaro.org> wrote:
> On 18-02-21, 16:25, Yue Hu wrote:
> > From: Yue Hu <huy...@yulong.com>
> >
> > For busy CPU case, we do not need to avoid freq reduction if limits
> > change since commit 600f5badb78c ("cpufreq: schedutil: Don't skip
> > freq update when limits change").
> >
> > Later, commit 23a881852f3e ("cpufreq: schedutil: Don't skip freq
> > update if need_freq_update is set") discarded the need_freq_update
> > check for special case of busy CPU because we won't abort a
> > frequency update anymore if need_freq_update is set.
> >
> > That is nonlogical since we will not reduce the freq for busy CPU
> > if the computed next_f is really reduced when limits change.
>
> Schedutil governor will probably ask for a higher frequency than
> allowed, but cpufreq core will clamp the request between policy
> min/max before updating the frequency here.
>
> We added the check in 600f5badb78c here earlier as there were chances
> that we will abort the operation without reaching to cpufreq core,
> which won't happen now.
>
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(). This possibility would happen now? And this
update is what we want if it happens? This is related to another
possible patch ready to send.
Thank you.
