linux-kernel - Re: [PATCH v1 12/16] thermal: gov_fair_share: Use trip thresholds instead of trip temperatures

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Message-ID: <adcc68df-e2dc-4865-9eb1-06b840538ce9@arm.com>
Date: Fri, 19 Apr 2024 20:18:08 +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>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v1 12/16] thermal: gov_fair_share: Use trip thresholds
 instead of trip temperatures



On 4/10/24 17:58, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> In principle, the Fair Share governor should take trip hystereses

s/hystereses/hysteresis/

> into account.  After all, once a trip has been crossed on the way up,
> mitigation is still needed until it is crossed on the way down.
> 
> For this reason, make it use trip thresholds that are computed by
> the core when trips are crossed, so as to apply mitigations if the
> zone temperature is in a hysteresis rage of one or more trips that
> were crossed on the way up, but have not been crossed on the way
> down yet.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>   drivers/thermal/gov_fair_share.c |   14 ++++++--------
>   1 file changed, 6 insertions(+), 8 deletions(-)
> 
> Index: linux-pm/drivers/thermal/gov_fair_share.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_fair_share.c
> +++ linux-pm/drivers/thermal/gov_fair_share.c
> @@ -17,28 +17,26 @@
>   
>   static int get_trip_level(struct thermal_zone_device *tz)
>   {
> -	const struct thermal_trip *level_trip = NULL;
> +	const struct thermal_trip_desc *level_td = NULL;
>   	const struct thermal_trip_desc *td;
>   	int trip_level = -1;
>   
>   	for_each_trip_desc(tz, td) {
> -		const struct thermal_trip *trip = &td->trip;
> -
> -		if (trip->temperature >= tz->temperature)
> +		if (td->threshold > tz->temperature)
>   			continue;
>   
>   		trip_level++;
>   
> -		if (!level_trip || trip->temperature > level_trip->temperature)
> -			level_trip = trip;
> +		if (!level_td || td->threshold > level_td->threshold)
> +			level_td = td;
>   	}
>   
>   	/*  Bail out if the temperature is not greater than any trips. */
>   	if (trip_level < 0)
>   		return 0;
>   
> -	trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, level_trip),
> -				level_trip->type);
> +	trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, &level_td->trip),
> +				level_td->trip.type);
>   
>   	return trip_level;
>   }
> 
> 
> 


LGTM w/ spelling fixed.

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