mirror of
https://github.com/flutter/flutter.git
synced 2026-02-20 02:29:02 +08:00
90 lines
2.9 KiB
C++
90 lines
2.9 KiB
C++
// Copyright 2013 The Flutter 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 FLUTTER_FML_CPU_AFFINITY_H_
|
|
#define FLUTTER_FML_CPU_AFFINITY_H_
|
|
|
|
#include <optional>
|
|
#include <string>
|
|
#include <vector>
|
|
|
|
namespace fml {
|
|
|
|
/// The CPU Affinity provides a hint to the operating system on which cores a
|
|
/// particular thread should be scheduled on. The operating system may or may
|
|
/// not honor these requests.
|
|
enum class CpuAffinity {
|
|
/// @brief Request CPU affinity for the performance cores.
|
|
///
|
|
/// Generally speaking, only the UI and Raster thread should
|
|
/// use this option.
|
|
kPerformance,
|
|
|
|
/// @brief Request CPU affinity for the efficiency cores.
|
|
kEfficiency,
|
|
|
|
/// @brief Request affinity for all non-performance cores.
|
|
kNotPerformance,
|
|
};
|
|
|
|
/// @brief Request count of efficiency cores.
|
|
///
|
|
/// Efficiency cores are defined as those with the lowest reported
|
|
/// cpu_max_freq. If the CPU speed could not be determined, or if all
|
|
/// cores have the same reported speed then this returns std::nullopt.
|
|
/// That is, the result will never be 0.
|
|
std::optional<size_t> EfficiencyCoreCount();
|
|
|
|
/// @brief Request the given affinity for the current thread.
|
|
///
|
|
/// Returns true if successfull, or if it was a no-op. This function is
|
|
/// only supported on Android devices.
|
|
///
|
|
/// Affinity requests are based on documented CPU speed. This speed data
|
|
/// is parsed from cpuinfo_max_freq files, see also:
|
|
/// https://www.kernel.org/doc/Documentation/cpu-freq/user-guide.txt
|
|
bool RequestAffinity(CpuAffinity affinity);
|
|
|
|
struct CpuIndexAndSpeed {
|
|
// The index of the given CPU.
|
|
size_t index;
|
|
// CPU speed in kHZ
|
|
int64_t speed;
|
|
};
|
|
|
|
/// @brief A class that computes the correct CPU indices for a requested CPU
|
|
/// affinity.
|
|
///
|
|
/// @note This is visible for testing.
|
|
class CPUSpeedTracker {
|
|
public:
|
|
explicit CPUSpeedTracker(std::vector<CpuIndexAndSpeed> data);
|
|
|
|
/// @brief The class is valid if it has more than one CPU index and a distinct
|
|
/// set of efficiency or performance CPUs.
|
|
///
|
|
/// If all CPUs are the same speed this returns false, and all requests
|
|
/// to set affinity are ignored.
|
|
bool IsValid() const;
|
|
|
|
/// @brief Return the set of CPU indices for the requested CPU affinity.
|
|
///
|
|
/// If the tracker is valid, this will always return a non-empty set.
|
|
const std::vector<size_t>& GetIndices(CpuAffinity affinity) const;
|
|
|
|
private:
|
|
bool valid_ = false;
|
|
std::vector<CpuIndexAndSpeed> cpu_speeds_;
|
|
std::vector<size_t> efficiency_;
|
|
std::vector<size_t> performance_;
|
|
std::vector<size_t> not_performance_;
|
|
};
|
|
|
|
/// @note Visible for testing.
|
|
std::optional<int64_t> ReadIntFromFile(const std::string& path);
|
|
|
|
} // namespace fml
|
|
|
|
#endif // FLUTTER_FML_CPU_AFFINITY_H_
|