114 lines
3.9 KiB
C++
114 lines
3.9 KiB
C++
// Copyright 2017 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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#include <algorithm>
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#include <chrono>
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#include <mutex>
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#include <thread>
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#include "common/math_util.h"
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#include "core/perf_stats.h"
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#include "core/settings.h"
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using namespace std::chrono_literals;
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using DoubleSecs = std::chrono::duration<double, std::chrono::seconds::period>;
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using std::chrono::duration_cast;
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using std::chrono::microseconds;
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namespace Core {
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void PerfStats::BeginSystemFrame() {
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std::lock_guard<std::mutex> lock(object_mutex);
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frame_begin = Clock::now();
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}
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void PerfStats::EndSystemFrame() {
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std::lock_guard<std::mutex> lock(object_mutex);
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auto frame_end = Clock::now();
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accumulated_frametime += frame_end - frame_begin;
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system_frames += 1;
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previous_frame_length = frame_end - previous_frame_end;
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previous_frame_end = frame_end;
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}
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void PerfStats::EndGameFrame() {
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std::lock_guard<std::mutex> lock(object_mutex);
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game_frames += 1;
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}
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PerfStats::Results PerfStats::GetAndResetStats(microseconds current_system_time_us) {
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std::lock_guard<std::mutex> lock(object_mutex);
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const auto now = Clock::now();
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// Walltime elapsed since stats were reset
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const auto interval = duration_cast<DoubleSecs>(now - reset_point).count();
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const auto system_us_per_second = (current_system_time_us - reset_point_system_us) / interval;
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Results results{};
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results.system_fps = static_cast<double>(system_frames) / interval;
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results.game_fps = static_cast<double>(game_frames) / interval;
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results.frametime = duration_cast<DoubleSecs>(accumulated_frametime).count() /
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static_cast<double>(system_frames);
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results.emulation_speed = system_us_per_second.count() / 1'000'000.0;
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// Reset counters
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reset_point = now;
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reset_point_system_us = current_system_time_us;
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accumulated_frametime = Clock::duration::zero();
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system_frames = 0;
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game_frames = 0;
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return results;
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}
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double PerfStats::GetLastFrameTimeScale() {
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std::lock_guard<std::mutex> lock(object_mutex);
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constexpr double FRAME_LENGTH = 1.0 / 60;
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return duration_cast<DoubleSecs>(previous_frame_length).count() / FRAME_LENGTH;
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}
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void FrameLimiter::DoFrameLimiting(microseconds current_system_time_us) {
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// Max lag caused by slow frames. Can be adjusted to compensate for too many slow frames. Higher
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// values increase the time needed to recover and limit framerate again after spikes.
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constexpr microseconds MAX_LAG_TIME_US = 25us;
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if (!Settings::values.use_frame_limit) {
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return;
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}
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auto now = Clock::now();
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const double sleep_scale = Settings::values.frame_limit / 100.0;
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// Max lag caused by slow frames. Shouldn't be more than the length of a frame at the current
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// speed percent or it will clamp too much and prevent this from properly limiting to that
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// percent. High values means it'll take longer after a slow frame to recover and start
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// limiting
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const microseconds max_lag_time_us = duration_cast<microseconds>(
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std::chrono::duration<double, std::chrono::microseconds::period>(25ms / sleep_scale));
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frame_limiting_delta_err += duration_cast<microseconds>(
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std::chrono::duration<double, std::chrono::microseconds::period>(
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(current_system_time_us - previous_system_time_us) / sleep_scale));
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frame_limiting_delta_err -= duration_cast<microseconds>(now - previous_walltime);
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frame_limiting_delta_err =
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std::clamp(frame_limiting_delta_err, -max_lag_time_us, max_lag_time_us);
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if (frame_limiting_delta_err > microseconds::zero()) {
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std::this_thread::sleep_for(frame_limiting_delta_err);
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auto now_after_sleep = Clock::now();
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frame_limiting_delta_err -= duration_cast<microseconds>(now_after_sleep - now);
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now = now_after_sleep;
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}
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previous_system_time_us = current_system_time_us;
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previous_walltime = now;
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}
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} // namespace Core
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