linux-kernel - Re: [PATCH v2 8/8] thermal: gov_power_allocator: Support new update callback of weights

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Date: Wed, 20 Dec 2023 15:59:17 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, daniel.lezcano@...aro.org, rafael@...nel.org, 
	linux-pm@...r.kernel.org, rui.zhang@...el.com
Subject: Re: [PATCH v2 8/8] thermal: gov_power_allocator: Support new update
 callback of weights

On Tue, Dec 12, 2023 at 2:48 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> When the thermal instance's weight is updated from the sysfs the governor
> update_tz() callback is triggered. Implement proper reaction to this
> event in the IPA, which would save CPU cycles spent in throttle().
> This will speed-up the main throttle() IPA function and clean it up
> a bit.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>  drivers/thermal/gov_power_allocator.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
> index 574aa5822112..a9f1549e6355 100644
> --- a/drivers/thermal/gov_power_allocator.c
> +++ b/drivers/thermal/gov_power_allocator.c
> @@ -61,6 +61,7 @@ static inline s64 div_frac(s64 x, s64 y)
>   *                     @trip_switch_on should be NULL.
>   * @trip_max:          last passive trip point of the thermal zone. The
>   *                     temperature we are controlling for.
> + * @total_weight:      Sum of all thermal instances weights
>   * @num_actors:                number of cooling devices supporting IPA callbacks
>   * @buffer_size:       IPA internal buffer size
>   * @req_power:         IPA buffer for requested power
> @@ -76,6 +77,7 @@ struct power_allocator_params {
>         u32 sustainable_power;
>         const struct thermal_trip *trip_switch_on;
>         const struct thermal_trip *trip_max;
> +       int total_weight;
>         int num_actors;
>         int buffer_size;
>         u32 *req_power;
> @@ -403,16 +405,11 @@ static int allocate_power(struct thermal_zone_device *tz, int control_temp)
>         u32 total_req_power = 0;
>         u32 *weighted_req_power;
>         u32 power_range, weight;
> -       int total_weight = 0;
>         int i = 0;
>
>         if (!params->num_actors)
>                 return -ENODEV;
>
> -       list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> -               if (power_actor_is_valid(params, instance))
> -                       total_weight += instance->weight;
> -
>         /* Clean all buffers for new power estimations */
>         memset(params->req_power, 0, params->buffer_size);
>
> @@ -430,7 +427,7 @@ static int allocate_power(struct thermal_zone_device *tz, int control_temp)
>                 if (cdev->ops->get_requested_power(cdev, &req_power[i]))
>                         continue;
>
> -               if (!total_weight)
> +               if (!params->total_weight)
>                         weight = 1 << FRAC_BITS;
>                 else
>                         weight = instance->weight;
> @@ -666,6 +663,12 @@ static void power_allocator_update_tz(struct thermal_zone_device *tz,
>
>                 allocate_actors_buffer(params, num_actors);
>                 break;
> +       case THERMAL_INSTANCE_WEIGHT_UPDATE:
> +               params->total_weight = 0;
> +               list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> +                       if (power_actor_is_valid(params, instance))
> +                               params->total_weight += instance->weight;
> +               break;
>         default:
>                 break;
>         }
> --

This one looks good to me, but if you decide to follow my advice from
the previous comments, it will need to be adjusted.