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From: Thomas Renninger <trenn@suse.de>
To: Rafael Wysocki <rjw@rjwysocki.net>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Shuah Khan <shuah@kernel.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cpufreq: stats: Switch to ktime and msec instead of jiffies and usertime
Date: Tue, 10 Nov 2020 13:53:08 +0100	[thread overview]
Message-ID: <1832747.5iOEhN7m9D@c100> (raw)
In-Reply-To: <0e0fb542b6f6b26944cb2cf356041348aeac95f6.1605006378.git.viresh.kumar@linaro.org>

Am Dienstag, 10. November 2020, 12:07:37 CET schrieb Viresh Kumar:
> The cpufreq and thermal core, both provide sysfs statistics to help
> userspace learn about the behavior of frequencies and cooling states.
> 
> This is how they look:
> /sys/devices/system/cpu/cpufreq/policy0/stats/time_in_state:1200000 399
 
> The results look like this after this commit:
> /sys/devices/system/cpu/cpufreq/policy0/stats/time_in_state:1200000 3830

How would userspace know whether it's ms or 10ms?

whatabout a new file with the same convention as cooling devices (adding ms):
 
> /sys/class/thermal/cooling_device0/stats/time_in_state_ms:state0 3888
> /sys/devices/system/cpu/cpufreq/policy0/stats/time_in_state_ms:1200000 3830

Somewhat off-topic, some ideas:

I wonder how useful these stats still are.
CPU_FREQ_STAT is off on my system:

config CPU_FREQ_STAT
        bool "CPU frequency transition statistics"
        help
          Export CPU frequency statistics information through sysfs.

          If in doubt, say N.

Iirc this was a module at former times?

commit 1aefc75b2449eb68a6fc3ca932e2a4ee353b748d
Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date:   Tue May 31 22:14:44 2016 +0200

    cpufreq: stats: Make the stats code non-modular

outlined 2 problems with cpufreq_stats being non-modular, but
also seem to fix them up:
... and drop the notifiers from it
Make the stats sysfs attributes appear empty if fast frequency
switching is enabled...

   Thomas



  parent reply	other threads:[~2020-11-10 12:53 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 11:07 [PATCH] cpufreq: stats: Switch to ktime and msec instead of jiffies and usertime Viresh Kumar
2020-11-10 11:36 ` Lukasz Luba
2020-11-11  5:14   ` Viresh Kumar
2020-11-10 12:53 ` Thomas Renninger [this message]
2020-11-11  5:13   ` Viresh Kumar
2020-11-11  8:13     ` Thomas Renninger
2020-11-11  9:51       ` Viresh Kumar
2020-11-10 12:59 ` Rafael J. Wysocki
2020-11-11  5:28   ` Viresh Kumar

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