dc8a3f8bc8
MSVC 2013 (at least) doesn't use QueryPerformanceCounter to implement std::chrono::high_resolution_clock, so it has bad precision. Manually implementing our own clock type using it works around this for now.
153 lines
3.9 KiB
C++
153 lines
3.9 KiB
C++
// Copyright 2015 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#pragma once
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#include <atomic>
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#include <chrono>
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#include "common/assert.h"
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#include "common/thread.h"
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namespace Common {
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namespace Profiling {
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// If this is defined to 0, it turns all Timers into no-ops.
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#ifndef ENABLE_PROFILING
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#define ENABLE_PROFILING 1
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#endif
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#if defined(_MSC_VER) && _MSC_VER <= 1800 // MSVC 2013
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// MSVC up to 2013 doesn't use QueryPerformanceCounter for high_resolution_clock, so it has bad
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// precision. We manually implement a clock based on QPC to get good results.
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struct QPCClock {
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using duration = std::chrono::microseconds;
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using time_point = std::chrono::time_point<QPCClock>;
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using rep = duration::rep;
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using period = duration::period;
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static const bool is_steady = false;
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static time_point now();
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};
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using Clock = QPCClock;
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#else
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using Clock = std::chrono::high_resolution_clock;
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#endif
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using Duration = Clock::duration;
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/**
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* Represents a timing category that measured time can be accounted towards. Should be declared as a
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* global variable and passed to Timers.
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*/
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class TimingCategory final {
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public:
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TimingCategory(const char* name, TimingCategory* parent = nullptr);
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unsigned int GetCategoryId() const {
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return category_id;
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}
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/// Adds some time to this category. Can safely be called from multiple threads at the same time.
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void AddTime(Duration amount) {
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std::atomic_fetch_add_explicit(
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&accumulated_duration, amount.count(),
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std::memory_order_relaxed);
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}
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/**
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* Atomically retrieves the accumulated measured time for this category and resets the counter
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* to zero. Can be safely called concurrently with AddTime.
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*/
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Duration GetAccumulatedTime() {
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return Duration(std::atomic_exchange_explicit(
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&accumulated_duration, (Duration::rep)0,
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std::memory_order_relaxed));
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}
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private:
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unsigned int category_id;
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std::atomic<Duration::rep> accumulated_duration;
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};
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/**
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* Measures time elapsed between a call to Start and a call to Stop and attributes it to the given
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* TimingCategory. Start/Stop can be called multiple times on the same timer, but each call must be
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* appropriately paired.
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*
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* When a Timer is started, it automatically pauses a previously running timer on the same thread,
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* which is resumed when it is stopped. As such, no special action needs to be taken to avoid
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* double-accounting of time on two categories.
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*/
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class Timer {
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public:
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Timer(TimingCategory& category) : category(category) {
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}
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void Start() {
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#if ENABLE_PROFILING
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ASSERT(!running);
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previous_timer = current_timer;
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current_timer = this;
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if (previous_timer != nullptr)
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previous_timer->StopTiming();
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StartTiming();
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#endif
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}
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void Stop() {
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#if ENABLE_PROFILING
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ASSERT(running);
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StopTiming();
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if (previous_timer != nullptr)
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previous_timer->StartTiming();
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current_timer = previous_timer;
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#endif
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}
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private:
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#if ENABLE_PROFILING
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void StartTiming() {
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start = Clock::now();
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running = true;
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}
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void StopTiming() {
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auto duration = Clock::now() - start;
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running = false;
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category.AddTime(std::chrono::duration_cast<Duration>(duration));
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}
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Clock::time_point start;
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bool running = false;
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Timer* previous_timer;
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static thread_local Timer* current_timer;
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#endif
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TimingCategory& category;
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};
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/**
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* A Timer that automatically starts timing when created and stops at the end of the scope. Should
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* be used in the majority of cases.
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*/
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class ScopeTimer : public Timer {
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public:
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ScopeTimer(TimingCategory& category) : Timer(category) {
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Start();
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}
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~ScopeTimer() {
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Stop();
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}
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};
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} // namespace Profiling
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} // namespace Common
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