linux-kernel - Re: [PATCH v1 1/3] thermal/debugfs: Avoid excessive updates of trip point statistics

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Message-ID: <fcb8851c-9b07-4d4c-bc22-8793bc59a50c@arm.com>
Date: Mon, 22 Apr 2024 12:14:56 +0100
From: Lukasz Luba <lukasz.luba@....com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH v1 1/3] thermal/debugfs: Avoid excessive updates of trip
 point statistics



On 4/17/24 14:09, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Since thermal_debug_update_temp() is called before invoking
> thermal_debug_tz_trip_down() for the trips that were crossed by the
> zone temperature on the way up, it updates the statistics for them
> as though the current zone temperature was above the low temperature
> of each of them.  However, if a given trip has just been crossed on the
> way down, the zone temperature is in fact below its low temperature,
> but this is handled by thermal_debug_tz_trip_down() running after the
> update of the trip statistics.
> 
> The remedy is to call thermal_debug_update_temp() after
> thermal_debug_tz_trip_down() has been invoked for all of the
> trips in question, but then thermal_debug_tz_trip_up() needs to
> be adjusted, so it does not update the statistics for the trips
> that has just been crossed on the way up, as that will be taken
> care of by thermal_debug_update_temp() down the road.
> 
> Modify the code accordingly.
> 
> Fixes: 7ef01f228c9f ("thermal/debugfs: Add thermal debugfs information for mitigation episodes")
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>   drivers/thermal/thermal_core.c    |    3 ++-
>   drivers/thermal/thermal_debugfs.c |    7 -------
>   2 files changed, 2 insertions(+), 8 deletions(-)
> 
> Index: linux-pm/drivers/thermal/thermal_core.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_core.c
> +++ linux-pm/drivers/thermal/thermal_core.c
> @@ -427,7 +427,6 @@ static void update_temperature(struct th
>   	trace_thermal_temperature(tz);
>   
>   	thermal_genl_sampling_temp(tz->id, temp);
> -	thermal_debug_update_temp(tz);
>   }
>   
>   static void thermal_zone_device_check(struct work_struct *work)
> @@ -505,6 +504,8 @@ void __thermal_zone_device_update(struct
>   	if (governor->manage)
>   		governor->manage(tz);
>   
> +	thermal_debug_update_temp(tz);
> +
>   	monitor_thermal_zone(tz);
>   }
>   
> Index: linux-pm/drivers/thermal/thermal_debugfs.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_debugfs.c
> +++ linux-pm/drivers/thermal/thermal_debugfs.c
> @@ -545,7 +545,6 @@ void thermal_debug_tz_trip_up(struct the
>   	struct tz_episode *tze;
>   	struct tz_debugfs *tz_dbg;
>   	struct thermal_debugfs *thermal_dbg = tz->debugfs;
> -	int temperature = tz->temperature;
>   	int trip_id = thermal_zone_trip_id(tz, trip);
>   	ktime_t now = ktime_get();
>   
> @@ -614,12 +613,6 @@ void thermal_debug_tz_trip_up(struct the
>   
>   	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;
>   
>   unlock:
>   	mutex_unlock(&thermal_dbg->lock);
> 
> 
> 
> 

Reviewed-by: Lukasz Luba <lukasz.luba@....com>