| // 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_UTIL_MEMORY_PRESSURE_SYSTEM_MEMORY_PRESSURE_EVALUATOR_LINUX_H_ |
| #define BASE_UTIL_MEMORY_PRESSURE_SYSTEM_MEMORY_PRESSURE_EVALUATOR_LINUX_H_ |
| |
| #include "base/memory/memory_pressure_listener.h" |
| #include "base/process/process_metrics.h" |
| #include "base/sequence_checker.h" |
| #include "base/timer/timer.h" |
| #include "base/util/memory_pressure/memory_pressure_voter.h" |
| #include "base/util/memory_pressure/system_memory_pressure_evaluator.h" |
| |
| namespace util { |
| namespace os_linux { |
| |
| // Linux memory pressure voter. Because there is no OS provided signal this |
| // polls at a low frequency, and applies internal hysteresis. |
| // TODO(https://crbug.com/1119396): use Pressure Stall Information (PSI) on |
| // kernels >4.20. |
| class SystemMemoryPressureEvaluator |
| : public util::SystemMemoryPressureEvaluator { |
| public: |
| using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel; |
| |
| // Constants governing the polling and hysteresis behaviour of the observer. |
| // The time which should pass between 2 successive moderate memory pressure |
| // signals. |
| static const base::TimeDelta kModeratePressureCooldown; |
| |
| // Default minimum free memory thresholds, in percents. |
| static const int kDefaultModerateThresholdPc; |
| static const int kDefaultCriticalThresholdPc; |
| |
| // Default constructor. Will choose thresholds automatically based on the |
| // actual amount of system memory. |
| explicit SystemMemoryPressureEvaluator( |
| std::unique_ptr<MemoryPressureVoter> voter); |
| |
| // Constructor with explicit memory thresholds. These represent the amount of |
| // free memory below which the applicable memory pressure state engages. |
| SystemMemoryPressureEvaluator(int moderate_threshold_mb, |
| int critical_threshold_mb, |
| std::unique_ptr<MemoryPressureVoter> voter); |
| |
| ~SystemMemoryPressureEvaluator() override = default; |
| |
| SystemMemoryPressureEvaluator(const SystemMemoryPressureEvaluator&) = delete; |
| SystemMemoryPressureEvaluator& operator=( |
| const SystemMemoryPressureEvaluator&) = delete; |
| |
| // Returns the moderate pressure level free memory threshold, in MB. |
| int moderate_threshold_mb() const { return moderate_threshold_mb_; } |
| |
| // Returns the critical pressure level free memory threshold, in MB. |
| int critical_threshold_mb() const { return critical_threshold_mb_; } |
| |
| protected: |
| // Internals are exposed for unittests. |
| |
| // Starts observing the memory fill level. Calls to StartObserving should |
| // always be matched with calls to StopObserving. |
| void StartObserving(); |
| |
| // Stop observing the memory fill level. May be safely called if |
| // StartObserving has not been called. Must be called from the same thread on |
| // which the monitor was instantiated. |
| void StopObserving(); |
| |
| // Checks memory pressure, storing the current level, applying any hysteresis |
| // and emitting memory pressure level change signals as necessary. This |
| // function is called periodically while the monitor is observing memory |
| // pressure. Must be called from the same thread on which the monitor was |
| // instantiated. |
| void CheckMemoryPressure(); |
| |
| // Automatically infers threshold values based on system memory. |
| // Returns 'true' if succeeded. |
| bool InferThresholds(); |
| |
| // Calculates the current instantaneous memory pressure level. This does not |
| // use any hysteresis and simply returns the result at the current moment. Can |
| // be called on any thread. |
| MemoryPressureLevel CalculateCurrentPressureLevel(); |
| |
| // This is just a wrapper for base:: function; |
| // declared as virtual for unit testing |
| virtual bool GetSystemMemoryInfo(base::SystemMemoryInfoKB* mem_info); |
| |
| private: |
| // Threshold amounts of available memory that trigger pressure levels |
| int moderate_threshold_mb_; |
| int critical_threshold_mb_; |
| |
| // A periodic timer to check for memory pressure changes. |
| base::RepeatingTimer timer_; |
| |
| // To slow down the amount of moderate pressure event calls, this gets used to |
| // count the number of events since the last event occurred. This is used by |
| // |CheckMemoryPressure| to apply hysteresis on the raw results of |
| // |CalculateCurrentPressureLevel|. |
| int moderate_pressure_repeat_count_; |
| |
| // Ensures that this object is used from a single sequence. |
| SEQUENCE_CHECKER(sequence_checker_); |
| }; |
| |
| } // namespace os_linux |
| } // namespace util |
| |
| #endif // BASE_UTIL_MEMORY_PRESSURE_SYSTEM_MEMORY_PRESSURE_EVALUATOR_LINUX_H_ |