bcdcbbc711
The fair share governor has the concept of weights, which is the influence of each cooling device in a thermal zone. The current implementation forces the weights of all cooling devices in a thermal zone to add up to a 100. This complicates setups, as you need to know in advance how many cooling devices you are going to have. If you bind a new cooling device, you have to modify all the other cooling devices weights, which is error prone. Furthermore, you can't specify a "default" weight for platforms since that default value depends on the number of cooling devices in the platform. This patch generalizes the concept of weight by allowing any number to be a "weight". Weights are now relative to each other. Platforms that don't specify weights get the same default value for all their cooling devices, so all their cdevs are considered to be equally influential. It's important to note that previous users of the weights don't need to alter the code: percentages continue to work as they used to. This patch just removes the constraint of all the weights in a thermal zone having to add up to a 100. If they do, you get the same behavior as before. If they don't, fair share now works for that platform. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Durgadoss R <durgadoss.r@intel.com> Acked-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
140 lines
4 KiB
C
140 lines
4 KiB
C
/*
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* fair_share.c - A simple weight based Thermal governor
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*
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* Copyright (C) 2012 Intel Corp
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* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#include <linux/thermal.h>
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#include <trace/events/thermal.h>
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#include "thermal_core.h"
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/**
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* get_trip_level: - obtains the current trip level for a zone
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* @tz: thermal zone device
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*/
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static int get_trip_level(struct thermal_zone_device *tz)
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{
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int count = 0;
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unsigned long trip_temp;
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enum thermal_trip_type trip_type;
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if (tz->trips == 0 || !tz->ops->get_trip_temp)
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return 0;
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for (count = 0; count < tz->trips; count++) {
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tz->ops->get_trip_temp(tz, count, &trip_temp);
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if (tz->temperature < trip_temp)
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break;
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}
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/*
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* count > 0 only if temperature is greater than first trip
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* point, in which case, trip_point = count - 1
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*/
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if (count > 0) {
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tz->ops->get_trip_type(tz, count - 1, &trip_type);
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trace_thermal_zone_trip(tz, count - 1, trip_type);
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}
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return count;
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}
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static long get_target_state(struct thermal_zone_device *tz,
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struct thermal_cooling_device *cdev, int percentage, int level)
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{
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unsigned long max_state;
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cdev->ops->get_max_state(cdev, &max_state);
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return (long)(percentage * level * max_state) / (100 * tz->trips);
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}
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/**
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* fair_share_throttle - throttles devices associated with the given zone
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* @tz - thermal_zone_device
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*
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* Throttling Logic: This uses three parameters to calculate the new
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* throttle state of the cooling devices associated with the given zone.
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*
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* Parameters used for Throttling:
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* P1. max_state: Maximum throttle state exposed by the cooling device.
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* P2. percentage[i]/100:
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* How 'effective' the 'i'th device is, in cooling the given zone.
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* P3. cur_trip_level/max_no_of_trips:
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* This describes the extent to which the devices should be throttled.
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* We do not want to throttle too much when we trip a lower temperature,
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* whereas the throttling is at full swing if we trip critical levels.
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* (Heavily assumes the trip points are in ascending order)
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* new_state of cooling device = P3 * P2 * P1
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*/
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static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
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{
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struct thermal_instance *instance;
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int total_weight = 0;
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int total_instance = 0;
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int cur_trip_level = get_trip_level(tz);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
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if (instance->trip != trip)
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continue;
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total_weight += instance->weight;
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total_instance++;
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}
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
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int percentage;
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struct thermal_cooling_device *cdev = instance->cdev;
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if (instance->trip != trip)
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continue;
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if (!total_weight)
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percentage = 100 / total_instance;
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else
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percentage = (instance->weight * 100) / total_weight;
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instance->target = get_target_state(tz, cdev, percentage,
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cur_trip_level);
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instance->cdev->updated = false;
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thermal_cdev_update(cdev);
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}
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return 0;
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}
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static struct thermal_governor thermal_gov_fair_share = {
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.name = "fair_share",
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.throttle = fair_share_throttle,
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};
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int thermal_gov_fair_share_register(void)
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{
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return thermal_register_governor(&thermal_gov_fair_share);
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}
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void thermal_gov_fair_share_unregister(void)
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{
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thermal_unregister_governor(&thermal_gov_fair_share);
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}
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