public inbox for linux-pm@vger.kernel.org
 help / color / mirror / Atom feed
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Philipp Miedl <philipp.miedl@tik.ee.ethz.ch>
Cc: alex@digriz.org.uk, jun.nakajima@intel.com,
	venkatesh.pallipadi@intel.com,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Subject: Re: Delayed acpi frequency governor call
Date: Tue, 24 Jan 2017 09:52:35 +0530	[thread overview]
Message-ID: <20170124042235.GA16906@vireshk-i7> (raw)
In-Reply-To: <086bc55f-d1cc-b893-49c6-1667f6067f1b@tik.ee.ethz.ch>

On 23-01-17, 15:24, Philipp Miedl wrote:
> I would say it only checks whether the elapsed time since the last governor
> call. My question is whether the call to the governor can be delayed for
> such a long time without the CPU going into idle? If it can be guaranteed
> that the governor call cannot be delayed without the CPU going to idle than
> it is true - otherwise not.

You are using a 4.4 kernel, which used the older delayed work stuff at sampling
rate. This has all changed a lot and we hooks paired with the scheduler now to
do this instead. Things have mostly changed since 4.7. Would it be possible for
you to use a later kernel and see if you still see something wrong?

Now coming back to 4.4, the timers (in the delayed works) can't get delayed but
the work can as it is just another process. But your setup has no almost load
and that seems unlikely as well. So, it looks to be a problem at some other
place. Tracers are your friend, only those can confirm something here.

-- 
viresh

  reply	other threads:[~2017-01-24  4:28 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <c8ee7078-ad5a-0a23-66ae-620c507300e5@tik.ee.ethz.ch>
2017-01-20 10:07 ` Delayed acpi frequency governor call Viresh Kumar
2017-01-20 15:27   ` Philipp Miedl
2017-01-23 10:11     ` Viresh Kumar
2017-01-23 14:24       ` Philipp Miedl
2017-01-24  4:22         ` Viresh Kumar [this message]
2017-01-24 14:49           ` Philipp Miedl
2017-01-25  3:23             ` Viresh Kumar
2017-01-25  9:48               ` Philipp Miedl

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=20170124042235.GA16906@vireshk-i7 \
    --to=viresh.kumar@linaro.org \
    --cc=alex@digriz.org.uk \
    --cc=jun.nakajima@intel.com \
    --cc=linux-pm@vger.kernel.org \
    --cc=philipp.miedl@tik.ee.ethz.ch \
    --cc=venkatesh.pallipadi@intel.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