| // Copyright 2020 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_POWER_MONITOR_SPEED_LIMIT_OBSERVER_WIN_H_ |
| #define BASE_POWER_MONITOR_SPEED_LIMIT_OBSERVER_WIN_H_ |
| |
| #include "base/base_export.h" |
| #include "base/callback.h" |
| #include "base/power_monitor/moving_average.h" |
| #include "base/power_monitor/power_observer.h" |
| #include "base/time/time.h" |
| #include "base/timer/timer.h" |
| |
| namespace base { |
| |
| // This class is used to listen for speed-limit changes and route new values to |
| // PowerMonitorSource when they are changed. The speed-limit value represents |
| // how well the CPU is running, where 100 means that it is running at normal |
| // speed (not throttled) and 0 means that it is so severely throttled (thermal |
| // throttling, power throttling, or other) that it is not running at all. |
| // A value under 70 indicates noticeable throttling, and a value under 40 |
| // indicates severe throttling. Well designed systems with sufficient power |
| // and cooling should be able to run with no throttling, but some systems |
| // (laptops in particular) may be throttled, especially in hot environments or |
| // when running on battery. On a well designed computer this metric should stay |
| // at 100, only going lower if there is insufficient cooling or power. |
| class BASE_EXPORT SpeedLimitObserverWin final { |
| public: |
| typedef base::RepeatingCallback<void(int)> SpeedLimitUpdateCallback; |
| |
| explicit SpeedLimitObserverWin( |
| SpeedLimitUpdateCallback speed_limit_update_callback); |
| ~SpeedLimitObserverWin(); |
| |
| private: |
| int GetCurrentSpeedLimit(); |
| void OnTimerTick(); |
| float EstimateThrottlingLevel(); |
| |
| int num_cpus() const { return num_cpus_; } |
| |
| const SpeedLimitUpdateCallback callback_; |
| |
| // Periodically calls OnTimerTick() where a new speed-limit metric is |
| // calculated. The timer is cancelled once this object is destroyed. |
| base::RepeatingTimer timer_; |
| // Number of logical cores in the existing physical processor. |
| // Example: a processor with 6 cores which supports hyperthreading has 12 |
| // logical cores, hence `num_cpus_` equals 12 in this case. |
| const int num_cpus_; |
| // A simple MA filter of size 10 is used to smooth out the speed-limit |
| // value and to remove noise from short spikes in CPU load. The existing |
| // sample rate is one sample per seconds but the existing choice is rather |
| // ad-hoc and not based on any deeper analysis into exact frequency |
| // characteristics of the underlying process. |
| MovingAverage moving_average_; |
| // Max speed-limit value is 100 (%) and it is also used in cases where the |
| // native Windows API(s) fail. |
| int speed_limit_ = PowerThermalObserver::kSpeedLimitMax; |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_POWER_MONITOR_SPEED_LIMIT_OBSERVER_WIN_H_ |