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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_POWER_MONITOR_CPU_FREQUENCY_UTILS_H_
#define BASE_POWER_MONITOR_CPU_FREQUENCY_UTILS_H_
#include <optional>
#include "base/base_export.h"
#include "base/time/time.h"
#include "base/values.h"
namespace base {
struct BASE_EXPORT CpuFrequencyInfo {
// These fields map to fields in the win32 PROCESSOR_POWER_INFORMATION
// struct. They are currently only implemented on Windows since that's
// the platform being investigated, but they could be replaced with
// something more generic/cross-platform as needed.
// The maximum frequency or the frequency limit of a CPU.
unsigned long max_mhz;
unsigned long mhz_limit;
enum class CoreType {
kPerformance,
kBalanced,
kEfficiency,
};
// A best effort guess at whether the associated CPU core is a performance
// core, an efficiency core, or something in between (balanced).
CoreType type;
// The number of CPU cores that are in the C0 state (active).
size_t num_active_cpus;
};
struct BASE_EXPORT CpuThroughputEstimationResult {
// The estimated CPU frequency of the current core, in Hz.
double estimated_frequency;
// True if the current core is different after the estimation loop than
// before.
bool migrated;
// The wall time and thread time of the CPU estimation task's assembly loop.
base::TimeDelta wall_time;
base::TimeDelta thread_time;
};
// Returns the estimated CPU frequency of the current core by executing a tight
// loop of predictable assembly instructions. The estimated frequency should be
// proportional to and about the same magnitude as the real CPU frequency,
// although it is possible for the code to be migrated/descheduled during the
// execution of this function. The measurement should be long enough to avoid
// Turbo Boost effect (~3ms) and be low enough to stay within the operating
// system scheduler quantum (~100ms).
// The return value is the estimated CPU frequency, in Hz.
BASE_EXPORT double EstimateCpuFrequency();
BASE_EXPORT std::optional<CpuThroughputEstimationResult>
EstimateCpuThroughput();
// Populates and returns a `CpuFrequencyInfo` struct with information from the
// current CPU core.
BASE_EXPORT CpuFrequencyInfo GetCpuFrequencyInfo();
#if BUILDFLAG(IS_WIN)
BASE_EXPORT void GenerateCpuInfoForTracingMetadata(base::Value::Dict* metadata);
#endif
} // namespace base
#endif // BASE_POWER_MONITOR_CPU_FREQUENCY_UTILS_H_
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