linux-kernel - Re: [PATCH v1 08/16] thermal: gov_step_wise: Use .manage() callback instead of .throttle()

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Message-ID: <5b65dc57-5503-4f9b-948a-6146185f5faf@arm.com>
Date: Fri, 19 Apr 2024 18:20:00 +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 08/16] thermal: gov_step_wise: Use .manage() callback
 instead of .throttle()



On 4/10/24 17:13, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Make the Step-Wise governor use the new .manage() callback instead of
> .throttle().
> 
> Even though using .throttle() is not particularly problematic for the
> Step-Wise governor, using .manage() instead still allows it to reduce
> overhead by updating all of the colling devices once after setting

s/colling/cooling/

> target values for all of the thermal instances.

Make sense, good observation, it's pointless to call the
thermal_cdev_update() in each trip point throttle() invocation.

> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>   drivers/thermal/gov_step_wise.c |   39 +++++++++++++++++++++------------------
>   1 file changed, 21 insertions(+), 18 deletions(-)
> 
> Index: linux-pm/drivers/thermal/gov_step_wise.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_step_wise.c
> +++ linux-pm/drivers/thermal/gov_step_wise.c
> @@ -109,34 +109,37 @@ static void thermal_zone_trip_update(str
>   	}
>   }
>   
> -/**
> - * step_wise_throttle - throttles devices associated with the given zone
> - * @tz: thermal_zone_device
> - * @trip: trip point
> - *
> - * Throttling Logic: This uses the trend of the thermal zone to throttle.
> - * If the thermal zone is 'heating up' this throttles all the cooling
> - * devices associated with the zone and its particular trip point, by one
> - * step. If the zone is 'cooling down' it brings back the performance of
> - * the devices by one step.
> - */
> -static int step_wise_throttle(struct thermal_zone_device *tz,
> -			      const struct thermal_trip *trip)
> +static void step_wise_manage(struct thermal_zone_device *tz)
>   {
> +	const struct thermal_trip_desc *td;
>   	struct thermal_instance *instance;
>   
>   	lockdep_assert_held(&tz->lock);
>   
> -	thermal_zone_trip_update(tz, trip);
> +	/*
> +	 * Throttling Logic: Use the trend of the thermal zone to throttle.
> +	 * If the thermal zone is 'heating up', throttle all of the cooling
> +	 * devices associated with each trip point by one step. If the zone
> +	 * is 'cooling down', it brings back the performance of the devices
> +	 * by one step.
> +	 */
> +	for_each_trip_desc(tz, td) {
> +		const struct thermal_trip *trip = &td->trip;
> +
> +		if (trip->temperature == THERMAL_TEMP_INVALID ||
> +		    trip->type == THERMAL_TRIP_CRITICAL ||
> +		    trip->type == THERMAL_TRIP_HOT)
> +			continue;
> +
> +		thermal_zone_trip_update(tz, trip);
> +	}
>   
>   	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
>   		thermal_cdev_update(instance->cdev);
> -
> -	return 0;
>   }
>   
>   static struct thermal_governor thermal_gov_step_wise = {
> -	.name		= "step_wise",
> -	.throttle	= step_wise_throttle,
> +	.name	= "step_wise",
> +	.manage	= step_wise_manage,
>   };
>   THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
> 
> 
> 

LGTM w/ that 'cooling' spelling fixed.

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