linux-kernel - [PATCH 5/7] thermal: stats: introduce tz time in trip

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Date:   Tue, 20 Jun 2023 21:45:20 -0700
From:   Eduardo Valentin <evalenti@...nel.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Eduardo Valentin <evalenti@...nel.org>, eduval@...zon.com,
        linux-pm@...r.kernel.org,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 5/7] thermal: stats: introduce tz time in trip

On Tue, Jun 20, 2023 at 07:27:57PM +0200, Rafael J. Wysocki wrote:
> 
> 
> 
> On Fri, May 19, 2023 at 5:27 AM Eduardo Valentin <evalenti@...nel.org> wrote:
> >
> > From: Eduardo Valentin <eduval@...zon.com>
> >
> > This patch adds a statistic to report how long
> > the thermal zone spent on temperature intervals
> > created by each trip point. The first interval
> > is the range below the first trip point. All
> > subsequent intervals are accounted when temperature
> > is above the trip point temperature value.
> >
> > Samples:
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> 
> The above line is confusing.
> 
> > trip0   -10000  35188
> > trip1   25000   0
> 
> And the format violates the "one value per attribute" sysfs rule.
> 
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> > trip0   -10000  36901
> > trip1   25000   0
> > $ echo 25001 > /sys//class/thermal/thermal_zone0/emul_temp
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> > trip0   -10000  47810
> > trip1   25000   2259
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> > trip0   -10000  47810
> > trip1   25000   3224
> > $ echo 24001 > /sys//class/thermal/thermal_zone0/emul_temp
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> > trip0   -10000  48960
> > trip1   25000   10080
> > $ cat /sys//class/thermal/thermal_zone0/stats/time_in_trip_ms
> > trip-1  0       0
> > trip0   -10000  49844
> > trip1   25000   10080
> >
> > Cc: "Rafael J. Wysocki" <rafael@...nel.org> (supporter:THERMAL)
> > Cc: Daniel Lezcano <daniel.lezcano@...aro.org> (supporter:THERMAL)
> > Cc: Amit Kucheria <amitk@...nel.org> (reviewer:THERMAL)
> > Cc: Zhang Rui <rui.zhang@...el.com> (reviewer:THERMAL)
> > Cc: Jonathan Corbet <corbet@....net> (maintainer:DOCUMENTATION)
> > Cc: linux-pm@...r.kernel.org (open list:THERMAL)
> > Cc: linux-doc@...r.kernel.org (open list:DOCUMENTATION)
> > Cc: linux-kernel@...r.kernel.org (open list)
> >
> > Signed-off-by: Eduardo Valentin <eduval@...zon.com>
> > ---
> >  .../driver-api/thermal/sysfs-api.rst          |  2 +
> >  drivers/thermal/thermal_sysfs.c               | 86 +++++++++++++++++++
> >  2 files changed, 88 insertions(+)
> >
> > diff --git a/Documentation/driver-api/thermal/sysfs-api.rst b/Documentation/driver-api/thermal/sysfs-api.rst
> > index ed5e6ba4e0d7..4a2b92a7488c 100644
> > --- a/Documentation/driver-api/thermal/sysfs-api.rst
> > +++ b/Documentation/driver-api/thermal/sysfs-api.rst
> > @@ -359,6 +359,8 @@ Thermal zone device sys I/F, created once it's registered::
> >      |---stats/reset_tz_stats:  Writes to this file resets the statistics.
> >      |---stats/max_gradient:    The maximum recorded dT/dt in uC/ms.
> >      |---stats/min_gradient:    The minimum recorded dT/dt in uC/ms.
> > +    |---stats/time_in_trip_ms: Time spent on each temperature interval of
> > +                               trip points.
> 
> I would write "in each temperature interval between consecutive trip points".

Ok

> 
> Doesn't this assume a specific temperature ordering of trip points?
> And so what if they are not ordered?

It does. I believe other things will break if they are not ordered. Like the temperature update
against the governor throttle callback invocation in the thermal core.


-- 
All the best,
Eduardo Valentin