Re: [PATCH v1 07/13] thermal: gov_power_allocator: Use trip pointers instead of trip indices

Daniel Lezcano
2023-09-27T15:10:58Z

On 21/09/2023 19:55, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Eliminate the __thermal_zone_get_trip() usage that adds unnecessary
> overhead (due to pointless bounds checking and copying of trip point
> data) from the power allocator thermal governor and generally make it
> use trip pointers instead of trip indices where applicable.

Actually the __thermal_zone_get_trip() change was done on purpose to
replace the 'throttle' callback index parameter by the trip pointer and
removing those call to __thermal_zone_get_trip() while the code was
using the trip pointer.

IMO, the changes should focus on changing the trip_index parameter by
the trip pointer directly in the throttle ops. The pointer can be
retrieved in the handle_thermal_trip() function and passed around for
the rest of the actions on this trip point

> The general functionality is not expected to be changed.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/thermal/gov_power_allocator.c | 102 ++++++++++++----------------------
> 1 file changed, 38 insertions(+), 64 deletions(-)
>
> Index: linux-pm/drivers/thermal/gov_power_allocator.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_power_allocator.c
> +++ linux-pm/drivers/thermal/gov_power_allocator.c
> @@ -16,8 +16,6 @@
>
> #include "thermal_core.h"
>
> -#define INVALID_TRIP -1
> -
> #define FRAC_BITS 10
> #define int_to_frac(x) ((x) << FRAC_BITS)
> #define frac_to_int(x) ((x) >> FRAC_BITS)
> @@ -55,23 +53,23 @@ static inline s64 div_frac(s64 x, s64 y)
> * @err_integral: accumulated error in the PID controller.
> * @prev_err: error in the previous iteration of the PID controller.
> * Used to calculate the derivative term.
> + * @sustainable_power: Sustainable power (heat) that this thermal zone can
> + * dissipate
> * @trip_switch_on: first passive trip point of the thermal zone. The
> * governor switches on when this trip point is crossed.
> * If the thermal zone only has one passive trip point,
> - * @trip_switch_on should be INVALID_TRIP.
> + * @trip_switch_on should be NULL.
> * @trip_max_desired_temperature: last passive trip point of the thermal
> * zone. The temperature we are
> * controlling for.
> - * @sustainable_power: Sustainable power (heat) that this thermal zone can
> - * dissipate
> */
> struct power_allocator_params {
> bool allocated_tzp;
> s64 err_integral;
> s32 prev_err;
> - int trip_switch_on;
> - int trip_max_desired_temperature;
> u32 sustainable_power;
> + const struct thermal_trip *trip_switch_on;
> + const struct thermal_trip *trip_max_desired_temperature;
> };
>
> /**
> @@ -90,14 +88,12 @@ static u32 estimate_sustainable_power(st
> u32 sustainable_power = 0;
> struct thermal_instance *instance;
> struct power_allocator_params *params = tz->governor_data;
> - const struct thermal_trip *trip_max_desired_temperature =
> - &tz->trips[params->trip_max_desired_temperature];
>
> list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> struct thermal_cooling_device *cdev = instance->cdev;
> u32 min_power;
>
> - if (instance->trip != trip_max_desired_temperature)
> + if (instance->trip != params->trip_max_desired_temperature)
> continue;
>
> if (!cdev_is_power_actor(cdev))
> @@ -116,24 +112,23 @@ static u32 estimate_sustainable_power(st
> * estimate_pid_constants() - Estimate the constants for the PID controller
> * @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
> + * @trip_switch_on: trip point for the switch on temperature
> * @control_temp: target temperature for the power allocator governor
> *
> * This function is used to update the estimation of the PID
> * controller constants in struct thermal_zone_parameters.
> */
> static void estimate_pid_constants(struct thermal_zone_device *tz,
> - u32 sustainable_power, int trip_switch_on,
> + u32 sustainable_power,
> + const struct thermal_trip *trip_switch_on,
> int control_temp)
> {
> - struct thermal_trip trip;
> u32 temperature_threshold = control_temp;
> int ret;
> s32 k_i;
>
> - ret = __thermal_zone_get_trip(tz, trip_switch_on, &trip);
> - if (!ret)
> - temperature_threshold -= trip.temperature;
> + if (trip_switch_on)
> + temperature_threshold -= trip_switch_on->temperature;
>
> /*
> * estimate_pid_constants() tries to find appropriate default
> @@ -386,7 +381,7 @@ static int allocate_power(struct thermal
> struct thermal_instance *instance;
> struct power_allocator_params *params = tz->governor_data;
> const struct thermal_trip *trip_max_desired_temperature =
> - &tz->trips[params->trip_max_desired_temperature];
> + params->trip_max_desired_temperature;
> u32 *req_power, *max_power, *granted_power, *extra_actor_power;
> u32 *weighted_req_power;
> u32 total_req_power, max_allocatable_power, total_weighted_req_power;
> @@ -513,46 +508,35 @@ static int allocate_power(struct thermal
> static void get_governor_trips(struct thermal_zone_device *tz,
> struct power_allocator_params *params)
> {
> - int i, last_active, last_passive;
> - bool found_first_passive;
> -
> - found_first_passive = false;
> - last_active = INVALID_TRIP;
> - last_passive = INVALID_TRIP;
> + const struct thermal_trip *last_active = NULL:
> + const struct thermal_trip *last_passive = NULL;
> + bool found_first_passive = false;
> + int i;
>
> for (i = 0; i < tz->num_trips; i++) {
> - struct thermal_trip trip;
> - int ret;
> + const struct thermal_trip *trip = &tz->trips[i];
>
> - ret = __thermal_zone_get_trip(tz, i, &trip);
> - if (ret) {
> - dev_warn(&tz->device,
> - "Failed to get trip point %d type: %d\n", i,
> - ret);
> - continue;
> - }
> -
> - if (trip.type == THERMAL_TRIP_PASSIVE) {
> + if (trip->type == THERMAL_TRIP_PASSIVE) {
> if (!found_first_passive) {
> - params->trip_switch_on = i;
> + params->trip_switch_on = trip;
> found_first_passive = true;
> } else {
> - last_passive = i;
> + last_passive = trip;
> }
> - } else if (trip.type == THERMAL_TRIP_ACTIVE) {
> - last_active = i;
> + } else if (trip->type == THERMAL_TRIP_ACTIVE) {
> + last_active = trip;
> } else {
> break;
> }
> }
>
> - if (last_passive != INVALID_TRIP) {
> + if (last_passive) {
> params->trip_max_desired_temperature = last_passive;
> } else if (found_first_passive) {
> params->trip_max_desired_temperature = params->trip_switch_on;
> - params->trip_switch_on = INVALID_TRIP;
> + params->trip_switch_on = NULL;
> } else {
> - params->trip_switch_on = INVALID_TRIP;
> + params->trip_switch_on = NULL;
> params->trip_max_desired_temperature = last_active;
> }
> }
> @@ -567,14 +551,12 @@ static void allow_maximum_power(struct t
> {
> struct thermal_instance *instance;
> struct power_allocator_params *params = tz->governor_data;
> - const struct thermal_trip *trip_max_desired_temperature =
> - &tz->trips[params->trip_max_desired_temperature];
> u32 req_power;
>
> list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> struct thermal_cooling_device *cdev = instance->cdev;
>
> - if ((instance->trip != trip_max_desired_temperature) ||
> + if (instance->trip != params->trip_max_desired_temperature ||
> (!cdev_is_power_actor(instance->cdev)))
> continue;
>
> @@ -636,7 +618,6 @@ static int power_allocator_bind(struct t
> {
> int ret;
> struct power_allocator_params *params;
> - struct thermal_trip trip;
>
> ret = check_power_actors(tz);
> if (ret)
> @@ -662,12 +643,13 @@ static int power_allocator_bind(struct t
> get_governor_trips(tz, params);
>
> if (tz->num_trips > 0) {
> - ret = __thermal_zone_get_trip(tz, params->trip_max_desired_temperature,
> - &trip);
> - if (!ret)
> + const struct thermal_trip *trip;
> +
> + trip = params->trip_max_desired_temperature;
> + if (trip)
> estimate_pid_constants(tz, tz->tzp->sustainable_power,
> params->trip_switch_on,
> - trip.temperature);
> + trip->temperature);
> }
>
> reset_pid_controller(params);
> @@ -697,11 +679,10 @@ static void power_allocator_unbind(struc
> tz->governor_data = NULL;
> }
>
> -static int power_allocator_throttle(struct thermal_zone_device *tz, int trip_id)
> +static int power_allocator_throttle(struct thermal_zone_device *tz, int trip_index)
> {
> struct power_allocator_params *params = tz->governor_data;
> - struct thermal_trip trip;
> - int ret;
> + const struct thermal_trip *trip = &tz->trips[trip_index];
> bool update;
>
> lockdep_assert_held(&tz->lock);
> @@ -710,12 +691,12 @@ static int power_allocator_throttle(stru
> * We get called for every trip point but we only need to do
> * our calculations once
> */
> - if (trip_id != params->trip_max_desired_temperature)
> + if (trip != params->trip_max_desired_temperature)
> return 0;
>
> - ret = __thermal_zone_get_trip(tz, params->trip_switch_on, &trip);
> - if (!ret && (tz->temperature < trip.temperature)) {
> - update = (tz->last_temperature >= trip.temperature);
> + trip = params->trip_switch_on;
> + if (trip && tz->temperature < trip->temperature) {
> + update = tz->last_temperature >= trip->temperature;
> tz->passive = 0;
> reset_pid_controller(params);
> allow_maximum_power(tz, update);
> @@ -724,14 +705,7 @@ static int power_allocator_throttle(stru
>
> tz->passive = 1;
>
> - ret = __thermal_zone_get_trip(tz, params->trip_max_desired_temperature, &trip);
> - if (ret) {
> - dev_warn(&tz->device, "Failed to get the maximum desired temperature: %d\n",
> - ret);
> - return ret;
> - }
> -
> - return allocate_power(tz, trip.temperature);
> + return allocate_power(tz, params->trip_max_desired_temperature->temperature);
> }
>
> static struct thermal_governor thermal_gov_power_allocator = {
>
>
>

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