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Message-ID: <20201009142347.GA3269@arm.com>
Date: Fri, 9 Oct 2020 15:23:47 +0100
From: Ionela Voinescu <ionela.voinescu@....com>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
daniel.lezcano@...aro.org, amitk@...nel.org,
Dietmar.Eggemann@....com
Subject: Re: [PATCH v3 2/2] thermal: power allocator: change how estimation
code is called
On Friday 09 Oct 2020 at 14:58:50 (+0100), Lukasz Luba wrote:
> The sustainable power value might come from the Device Tree or can be
> estimated in run time. There is no need to estimate every time when the
> governor is called and temperature is high. Instead, store the estimated
> value and make it available via standard sysfs interface so it can be
> checked from the user-space. Re-invoke the estimation only in case the
> sustainable power was set to 0. Apart from that the PID coefficients
> are not going to be force updated thus can better handle sysfs settings.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>
> v3:
> - changed estimate_pid_constants to estimate_tzp_constants and related comments
> - estimate the PID coefficients always together with sust. power
> - added print indicating that we are estimating sust. power and PID const.
> - don't use local variable 'sustainable_power'
>
>
> drivers/thermal/gov_power_allocator.c | 65 ++++++++++++---------------
> 1 file changed, 29 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
> index aa35aa6c561c..e92a8d3ca5d4 100644
> --- a/drivers/thermal/gov_power_allocator.c
> +++ b/drivers/thermal/gov_power_allocator.c
> @@ -96,6 +96,9 @@ static u32 estimate_sustainable_power(struct thermal_zone_device *tz)
> if (instance->trip != params->trip_max_desired_temperature)
> continue;
>
> + if (!cdev_is_power_actor(cdev))
> + continue;
> +
> if (cdev->ops->state2power(cdev, tz, instance->upper,
> &min_power))
> continue;
> @@ -107,40 +110,37 @@ static u32 estimate_sustainable_power(struct thermal_zone_device *tz)
> }
>
> /**
> - * estimate_pid_constants() - Estimate the constants for the PID controller
> + * estimate_tzp_constants() - Estimate sustainable power and PID constants
> * @tz: thermal zone for which to estimate the constants
> - * @sustainable_power: sustainable power for the thermal zone
> * @trip_switch_on: trip point number for the switch on temperature
> * @control_temp: target temperature for the power allocator governor
> - * @force: whether to force the update of the constants
> *
> - * This function is used to update the estimation of the PID
> - * controller constants in struct thermal_zone_parameters.
> - * Sustainable power is provided in case it was estimated. The
> - * estimated sustainable_power should not be stored in the
> - * thermal_zone_parameters so it has to be passed explicitly to this
> - * function.
> - *
> - * If @force is not set, the values in the thermal zone's parameters
> - * are preserved if they are not zero. If @force is set, the values
> - * in thermal zone's parameters are overwritten.
> + * This function is used to estimate the sustainable power and PID controller
> + * constants in struct thermal_zone_parameters. These estimations will then be
> + * available in the sysfs.
> */
> -static void estimate_pid_constants(struct thermal_zone_device *tz,
> - u32 sustainable_power, int trip_switch_on,
> - int control_temp, bool force)
> +static void estimate_tzp_constants(struct thermal_zone_device *tz,
> + int trip_switch_on, int control_temp)
> {
> - int ret;
> - int switch_on_temp;
> u32 temperature_threshold;
> + int switch_on_temp;
> + bool force = false;
> + int ret;
> s32 k_i;
>
> + if (!tz->tzp->sustainable_power) {
> + tz->tzp->sustainable_power = estimate_sustainable_power(tz);
> + force = true;
> + dev_info(&tz->device, "power_allocator: estimating sust. power and PID constants\n");
> + }
> +
> ret = tz->ops->get_trip_temp(tz, trip_switch_on, &switch_on_temp);
> if (ret)
> switch_on_temp = 0;
>
> temperature_threshold = control_temp - switch_on_temp;
> /*
> - * estimate_pid_constants() tries to find appropriate default
> + * estimate_tzp_constants() tries to find appropriate default
> * values for thermal zones that don't provide them. If a
> * system integrator has configured a thermal zone with two
> * passive trip points at the same temperature, that person
> @@ -151,11 +151,11 @@ static void estimate_pid_constants(struct thermal_zone_device *tz,
> return;
>
> if (!tz->tzp->k_po || force)
> - tz->tzp->k_po = int_to_frac(sustainable_power) /
> + tz->tzp->k_po = int_to_frac(tz->tzp->sustainable_power) /
> temperature_threshold;
>
> if (!tz->tzp->k_pu || force)
> - tz->tzp->k_pu = int_to_frac(2 * sustainable_power) /
> + tz->tzp->k_pu = int_to_frac(2 * tz->tzp->sustainable_power) /
> temperature_threshold;
>
> if (!tz->tzp->k_i || force) {
> @@ -193,19 +193,13 @@ static u32 pid_controller(struct thermal_zone_device *tz,
> {
> s64 p, i, d, power_range;
> s32 err, max_power_frac;
> - u32 sustainable_power;
> struct power_allocator_params *params = tz->governor_data;
>
> max_power_frac = int_to_frac(max_allocatable_power);
>
> - if (tz->tzp->sustainable_power) {
> - sustainable_power = tz->tzp->sustainable_power;
> - } else {
> - sustainable_power = estimate_sustainable_power(tz);
> - estimate_pid_constants(tz, sustainable_power,
> - params->trip_switch_on, control_temp,
> - true);
> - }
> + if (!tz->tzp->sustainable_power)
> + estimate_tzp_constants(tz, params->trip_switch_on,
> + control_temp);
>
> err = control_temp - tz->temperature;
> err = int_to_frac(err);
> @@ -244,7 +238,7 @@ static u32 pid_controller(struct thermal_zone_device *tz,
> power_range = p + i + d;
>
> /* feed-forward the known sustainable dissipatable power */
> - power_range = sustainable_power + frac_to_int(power_range);
> + power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
>
> power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power);
>
> @@ -603,20 +597,19 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
>
> get_governor_trips(tz, params);
>
> + tz->governor_data = params;
> +
> if (tz->trips > 0) {
> ret = tz->ops->get_trip_temp(tz,
> params->trip_max_desired_temperature,
> &control_temp);
> if (!ret)
> - estimate_pid_constants(tz, tz->tzp->sustainable_power,
> - params->trip_switch_on,
> - control_temp, false);
> + estimate_tzp_constants(tz, params->trip_switch_on,
> + control_temp);
> }
>
> reset_pid_controller(params);
>
> - tz->governor_data = params;
> -
> return 0;
>
> free_params:
> --
> 2.17.1
>
Awesome!
Reviewed-by: Ionela Voinescu <ionela.voinescu@....com>
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