From: Viresh Kumar <viresh.kumar@linaro.org>
To: Stratos Karafotis <stratosk@semaphore.gr>
Cc: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [Resend][PATCH] cpufreq: conservative: Decrease frequency faster when the timer deferred
Date: Tue, 8 Nov 2016 14:02:29 +0530 [thread overview]
Message-ID: <CAKohpo=kbyXvjOYFdOyu6d6x1TP45UWT0kB9eAk3XUXTG5iUpQ@mail.gmail.com> (raw)
In-Reply-To: <076fb177-9cb3-4534-aadb-ebc2190d0751@email.android.com>
On 8 November 2016 at 12:49, Stratos Karafotis <stratosk@semaphore.gr> wrote:
> I think we shouldn't. That's why the patch first decreases the frequency
> by n freq steps (where n the number of deferred periods).
> Then the normal processing takes place.
The problem that I see is that the new algorithm will reduce the
frequency even if we are
on a ramp up phase.
For example consider this case:
- We have a special load running, that runs in bursts. i.e. runs for
some time, lets the CPU idle
then and then again runs.
- To run the load properly, we need to ramp up the frequency
- But the new algorithm can make the frequency stagnant in this case.
i.e. because of the idle
period you may want to decrease the frequency by delta A and then the
regular algorithm may
want to increase it by same delta A.
That's why I was asking to adopt this only in the ramp down path.
--
viresh
next parent reply other threads:[~2016-11-08 8:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <076fb177-9cb3-4534-aadb-ebc2190d0751@email.android.com>
2016-11-08 8:32 ` Viresh Kumar [this message]
2016-11-08 19:25 ` [Resend][PATCH] cpufreq: conservative: Decrease frequency faster when the timer deferred Stratos Karafotis
2016-11-09 5:55 ` Viresh Kumar
2016-11-09 18:27 ` Stratos Karafotis
2016-11-10 0:13 ` Rafael J. Wysocki
2016-11-10 15:48 ` Stratos Karafotis
2016-11-06 9:19 Stratos Karafotis
2016-11-07 6:12 ` Viresh Kumar
2016-11-07 17:27 ` Stratos Karafotis
2016-11-08 4:04 ` Viresh Kumar
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='CAKohpo=kbyXvjOYFdOyu6d6x1TP45UWT0kB9eAk3XUXTG5iUpQ@mail.gmail.com' \
--to=viresh.kumar@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rjw@rjwysocki.net \
--cc=stratosk@semaphore.gr \
/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).