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thermal: gov_fair_share: Use .manage() callback instead of .throttle()

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The Fair Share governor tries very hard to be stateless and so it
calls get_trip_level() from fair_share_throttle() every time, even
though the number produced by this function for all of the trips
during a given thermal zone update is actually the same.  Since
get_trip_level() walks all of the trips in the thermal zone every
time it is called, doing this may generate quite a bit of completely
useless overhead.

For this reason, make the governor use the new .manage() callback
instead of .throttle() which allows it to call get_trip_level() just
once and use the value computed by it to handle all of the trips.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
This commit is contained in:
Rafael J. Wysocki 2024-04-10 18:57:38 +02:00
parent fe03626650
commit bec55332c2
1 changed files with 26 additions and 11 deletions
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35
drivers/thermal/gov_fair_share.c
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@ -53,6 +53,7 @@ static long get_target_state(struct thermal_zone_device *tz,
* fair_share_throttle - throttles devices associated with the given zone * fair_share_throttle - throttles devices associated with the given zone
* @tz: thermal_zone_device * @tz: thermal_zone_device
* @trip: trip point * @trip: trip point
* @trip_level: number of trips crossed by the zone temperature
* *
* Throttling Logic: This uses three parameters to calculate the new * Throttling Logic: This uses three parameters to calculate the new
* throttle state of the cooling devices associated with the given zone. * throttle state of the cooling devices associated with the given zone.
@ -61,22 +62,19 @@ static long get_target_state(struct thermal_zone_device *tz,
* P1. max_state: Maximum throttle state exposed by the cooling device. * P1. max_state: Maximum throttle state exposed by the cooling device.
* P2. percentage[i]/100: * P2. percentage[i]/100:
* How 'effective' the 'i'th device is, in cooling the given zone. * How 'effective' the 'i'th device is, in cooling the given zone.
* P3. cur_trip_level/max_no_of_trips: * P3. trip_level/max_no_of_trips:
* This describes the extent to which the devices should be throttled. * This describes the extent to which the devices should be throttled.
* We do not want to throttle too much when we trip a lower temperature, * We do not want to throttle too much when we trip a lower temperature,
* whereas the throttling is at full swing if we trip critical levels. * whereas the throttling is at full swing if we trip critical levels.
* (Heavily assumes the trip points are in ascending order)
* new_state of cooling device = P3 * P2 * P1 * new_state of cooling device = P3 * P2 * P1
*/ */
static int fair_share_throttle(struct thermal_zone_device *tz, static void fair_share_throttle(struct thermal_zone_device *tz,
const struct thermal_trip *trip) const struct thermal_trip *trip,
int trip_level)
{ {
struct thermal_instance *instance; struct thermal_instance *instance;
int total_weight = 0; int total_weight = 0;
int total_instance = 0; int total_instance = 0;
int cur_trip_level = get_trip_level(tz);
lockdep_assert_held(&tz->lock);
list_for_each_entry(instance, &tz->thermal_instances, tz_node) { list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (instance->trip != trip) if (instance->trip != trip)
@ -99,18 +97,35 @@ static int fair_share_throttle(struct thermal_zone_device *tz,
percentage = (instance->weight * 100) / total_weight; percentage = (instance->weight * 100) / total_weight;
instance->target = get_target_state(tz, cdev, percentage, instance->target = get_target_state(tz, cdev, percentage,
cur_trip_level); trip_level);
mutex_lock(&cdev->lock); mutex_lock(&cdev->lock);
__thermal_cdev_update(cdev); __thermal_cdev_update(cdev);
mutex_unlock(&cdev->lock); mutex_unlock(&cdev->lock);
} }
}
return 0; static void fair_share_manage(struct thermal_zone_device *tz)
{
int trip_level = get_trip_level(tz);
const struct thermal_trip_desc *td;
lockdep_assert_held(&tz->lock);
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;
fair_share_throttle(tz, trip, trip_level);
}
} }
static struct thermal_governor thermal_gov_fair_share = { static struct thermal_governor thermal_gov_fair_share = {
.name = "fair_share", .name = "fair_share",
.throttle = fair_share_throttle, .manage = fair_share_manage,
}; };
THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);