linux-kernel - Re: [PATCH V3] thermal: Add cooling device's statistics in sysfs

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Date:   Fri, 12 Jan 2018 16:39:43 +0530
From:   Aishwarya Pant <aishpant@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] thermal: Add cooling device's statistics in sysfs

On Thu, Jan 11, 2018 at 03:06:09PM +0530, Viresh Kumar wrote:
> This extends the sysfs interface for thermal cooling devices and exposes
> some pretty useful statistics. These statistics have proven to be quite
> useful specially while doing benchmarks related to the task scheduler,
> where we want to make sure that nothing has disrupted the test,
> specially the cooling device which may have put constraints on the CPUs.
> The information exposed here tells us to what extent the CPUs were
> constrained by the thermal framework.
> 
> The read-only "total_trans" file shows the total number of cooling state
> transitions the device has gone through since the time the cooling
> device is registered or the time when statistics were reset last.
> 
> The read-only "time_in_state_ms" file shows the time spent by the device
> in the respective cooling states.
> 
> The write-only "reset" file is used to reset the statistics.
> 
> This is how the directory structure looks like for a single cooling
> device:
> 
> $ ls -R /sys/class/thermal/cooling_device0/
> /sys/class/thermal/cooling_device0/:
> cur_state  max_state  power  stats  subsystem  type  uevent
> 
> /sys/class/thermal/cooling_device0/power:
> autosuspend_delay_ms  runtime_active_time  runtime_suspended_time
> control               runtime_status
> 
> /sys/class/thermal/cooling_device0/stats:
> reset  time_in_state_ms  total_trans
> 
> This is tested on ARM 32-bit Hisilicon hikey620 board running Ubuntu and
> ARM 64-bit Hisilicon hikey960 board running Android.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> V2->V3:
> - Total number of states is max_level + 1. The earlier version didn't
>   take that into account and so the stats for the highest state were
>   missing.
> 
> V1->V2:
> - Move to sysfs from debugfs
> 
>  drivers/thermal/thermal_core.c    |   3 +-
>  drivers/thermal/thermal_core.h    |   3 +
>  drivers/thermal/thermal_helpers.c |   5 +-
>  drivers/thermal/thermal_sysfs.c   | 146 ++++++++++++++++++++++++++++++++++++++
>  include/linux/thermal.h           |   1 +
>  5 files changed, 156 insertions(+), 2 deletions(-)

<snip>

> index 27e3b1df7360..f6eb01e99816 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
 +
> +static DEVICE_ATTR(total_trans, 0444, thermal_cooling_device_total_trans_show,
> +		   NULL);
> +static DEVICE_ATTR(time_in_state_ms, 0444,
> +		   thermal_cooling_device_time_in_state_show, NULL);
> +static DEVICE_ATTR(reset, 0200, NULL, thermal_cooling_device_reset_store);
> +

Hi

I can see that you have added some files to the sysfs ABI. It would be good to
have these new interfaces documented in Documentation/ABI.

Aishwarya

<snip>