linux-kernel - Re: [PATCH v1 2/2] thermal/debugfs: Add helper function for trip stats updates

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Date: Wed, 17 Apr 2024 11:35:15 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Linux PM <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, 
	Lukasz Luba <lukasz.luba@....com>, Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH v1 2/2] thermal/debugfs: Add helper function for trip
 stats updates

On Mon, Apr 15, 2024 at 9:03 PM Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> The code updating a trip_stats entry in thermal_debug_tz_trip_up()
> and thermal_debug_update_temp() is almost entirely duplicate, so move
> it to a new helper function that will be called from both these places.
>
> While at it, drop a redundant tz_dbg->nr_trips check and a label related
> to it from thermal_debug_update_temp().
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

In the meantime I realized that thermal_debug_update_temp() made
false-positive updates of trips involved in the current mitigation
episode in the cases when they were crossed on the way down.

Namely, in that case the zone temperature is already below the low
temperature of the trip, but that is only recorded by
thermal_debug_tz_trip_down() that is called after
thermal_debug_update_temp().

For this reason, I'm withdrawing this patch and I will send
replacement patches later today.

Thanks!

> ---
>  drivers/thermal/thermal_debugfs.c |   42 +++++++++++++++++---------------------
>  1 file changed, 19 insertions(+), 23 deletions(-)
>
> Index: linux-pm/drivers/thermal/thermal_debugfs.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_debugfs.c
> +++ linux-pm/drivers/thermal/thermal_debugfs.c
> @@ -539,6 +539,19 @@ static struct tz_episode *thermal_debugf
>         return tze;
>  }
>
> +static struct trip_stats *update_tz_episode(struct tz_debugfs *tz_dbg,
> +                                           int trip_id, int temperature)
> +{
> +       struct tz_episode *tze = list_first_entry(&tz_dbg->tz_episodes,
> +                                                 struct tz_episode, node);
> +       struct trip_stats *trip_stats = &tze->trip_stats[trip_id];
> +
> +       trip_stats->max = max(trip_stats->max, temperature);
> +       trip_stats->min = min(trip_stats->min, temperature);
> +       trip_stats->avg += (temperature - trip_stats->avg) / ++trip_stats->count;
> +       return trip_stats;
> +}
> +
>  void thermal_debug_tz_trip_up(struct thermal_zone_device *tz,
>                               const struct thermal_trip *trip)
>  {
> @@ -547,6 +560,7 @@ void thermal_debug_tz_trip_up(struct the
>         struct thermal_debugfs *thermal_dbg = tz->debugfs;
>         int temperature = tz->temperature;
>         int trip_id = thermal_zone_trip_id(tz, trip);
> +       struct trip_stats *trip_stats;
>         ktime_t now = ktime_get();
>
>         if (!thermal_dbg)
> @@ -612,14 +626,8 @@ void thermal_debug_tz_trip_up(struct the
>          */
>         tz_dbg->trips_crossed[tz_dbg->nr_trips++] = trip_id;
>
> -       tze = list_first_entry(&tz_dbg->tz_episodes, struct tz_episode, node);
> -       tze->trip_stats[trip_id].timestamp = now;
> -       tze->trip_stats[trip_id].max = max(tze->trip_stats[trip_id].max, temperature);
> -       tze->trip_stats[trip_id].min = min(tze->trip_stats[trip_id].min, temperature);
> -       tze->trip_stats[trip_id].count++;
> -       tze->trip_stats[trip_id].avg = tze->trip_stats[trip_id].avg +
> -               (temperature - tze->trip_stats[trip_id].avg) /
> -               tze->trip_stats[trip_id].count;
> +       trip_stats = update_tz_episode(tz_dbg, trip_id, temperature);
> +       trip_stats->timestamp = now;
>
>  unlock:
>         mutex_unlock(&thermal_dbg->lock);
> @@ -686,9 +694,8 @@ out:
>  void thermal_debug_update_temp(struct thermal_zone_device *tz)
>  {
>         struct thermal_debugfs *thermal_dbg = tz->debugfs;
> -       struct tz_episode *tze;
>         struct tz_debugfs *tz_dbg;
> -       int trip_id, i;
> +       int i;
>
>         if (!thermal_dbg)
>                 return;
> @@ -697,20 +704,9 @@ void thermal_debug_update_temp(struct th
>
>         tz_dbg = &thermal_dbg->tz_dbg;
>
> -       if (!tz_dbg->nr_trips)
> -               goto out;
> +       for (i = 0; i < tz_dbg->nr_trips; i++)
> +               update_tz_episode(tz_dbg, tz_dbg->trips_crossed[i], tz->temperature);
>
> -       for (i = 0; i < tz_dbg->nr_trips; i++) {
> -               trip_id = tz_dbg->trips_crossed[i];
> -               tze = list_first_entry(&tz_dbg->tz_episodes, struct tz_episode, node);
> -               tze->trip_stats[trip_id].count++;
> -               tze->trip_stats[trip_id].max = max(tze->trip_stats[trip_id].max, tz->temperature);
> -               tze->trip_stats[trip_id].min = min(tze->trip_stats[trip_id].min, tz->temperature);
> -               tze->trip_stats[trip_id].avg = tze->trip_stats[trip_id]avg +
> -                       (tz->temperature - tze->trip_stats[trip_id].avg) /
> -                       tze->trip_stats[trip_id].count;
> -       }
> -out:
>         mutex_unlock(&thermal_dbg->lock);
>  }
>
>
>
>
>