64 lines
1.9 KiB
C++
64 lines
1.9 KiB
C++
// Copyright 2022 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_ANDROID_THREAD_INSTRUCTION_COUNT_H_
|
|
#define BASE_ANDROID_THREAD_INSTRUCTION_COUNT_H_
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "base/base_export.h"
|
|
|
|
namespace base {
|
|
namespace android {
|
|
|
|
// Represents the number of instructions that were retired between two samples
|
|
// of a thread's performance counters.
|
|
class BASE_EXPORT ThreadInstructionDelta {
|
|
public:
|
|
constexpr ThreadInstructionDelta() : delta_(0) {}
|
|
explicit constexpr ThreadInstructionDelta(int64_t delta) : delta_(delta) {}
|
|
|
|
constexpr int64_t ToInternalValue() const { return delta_; }
|
|
|
|
private:
|
|
int64_t delta_;
|
|
};
|
|
|
|
// Helper class for reading the current count of instructions retired for the
|
|
// current thread via ThreadInstructionCount::Now(). Does *not* count
|
|
// instructions retired while running in the kernel.
|
|
//
|
|
// Limitations:
|
|
// * Crashes when used in sandboxed process
|
|
// * Works on a userdebug build of Android 12, kernel 4.19. May require extra
|
|
// effort to allow on later Android releases and kernel versions.
|
|
class BASE_EXPORT ThreadInstructionCount {
|
|
public:
|
|
// Returns true if the platform supports hardware retired instruction
|
|
// counters. May crash in sandboxed processes.
|
|
static bool IsSupported();
|
|
|
|
// Returns the number of retired instructions relative to some epoch count,
|
|
// or 0 if getting the current instruction count failed / is disabled.
|
|
static ThreadInstructionCount Now();
|
|
|
|
explicit constexpr ThreadInstructionCount(uint64_t value = 0)
|
|
: value_(value) {}
|
|
|
|
constexpr ThreadInstructionDelta operator-(
|
|
ThreadInstructionCount other) const {
|
|
return ThreadInstructionDelta(static_cast<int64_t>(value_ - other.value_));
|
|
}
|
|
|
|
constexpr uint64_t ToInternalValue() const { return value_; }
|
|
|
|
private:
|
|
uint64_t value_;
|
|
};
|
|
|
|
} // namespace android
|
|
} // namespace base
|
|
|
|
#endif // BASE_ANDROID_THREAD_INSTRUCTION_COUNT_H_
|