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

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Date:   Tue, 20 Jun 2023 19:27:57 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Eduardo Valentin <evalenti@...nel.org>
Cc:     eduval@...zon.com, linux-pm@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.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: Re: [PATCH 5/7] thermal: stats: introduce tz time in trip

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".

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