From: Yue Hu <zbestahu@gmail.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
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
Date: Fri, 19 Feb 2021 11:38:04 +0800 [thread overview]
Message-ID: <20210219113804.00004a7e.zbestahu@gmail.com> (raw)
In-Reply-To: <20210218102029.syj6vkltlbtoxsig@vireshk-i7>
On Thu, 18 Feb 2021 15:50:29 +0530
Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 18-02-21, 16:25, Yue Hu wrote:
> > From: Yue Hu <huyue2@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.
next prev parent reply other threads:[~2021-02-19 3:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210218082514.1437-1-zbestahu@gmail.com>
2021-02-18 10:20 ` [PATCH] cpufreq: schedutil: Don't consider freq reduction to busy CPU if need_freq_update is set Viresh Kumar
2021-02-19 3:38 ` Yue Hu [this message]
2021-02-19 4:09 ` Viresh Kumar
2021-02-19 6:41 ` Yue Hu
2021-02-19 7:42 ` Viresh Kumar
2021-02-19 8:20 ` Yue Hu
2021-02-19 9:35 ` Viresh Kumar
2021-02-19 11:45 ` Yue Hu
2021-02-22 5:30 ` Viresh Kumar
2021-02-22 9:04 ` Yue Hu
2021-02-22 14:30 ` Rafael J. Wysocki
2021-02-24 2:24 ` Yue Hu
2021-02-24 12:46 ` Rafael J. Wysocki
2021-02-25 1:38 ` Yue Hu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210219113804.00004a7e.zbestahu@gmail.com \
--to=zbestahu@gmail.com \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=huyue2@yulong.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rjw@rjwysocki.net \
--cc=rostedt@goodmis.org \
--cc=vincent.guittot@linaro.org \
--cc=viresh.kumar@linaro.org \
--cc=zbestahu@163.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).