yuzu/src/common/wall_clock.cpp
Morph bff1453282 core_timing: Use higher precision sleeps on Windows
The precision of sleep_for and wait_for is limited to 1-1.5ms on Windows.
Using SleepForOneTick() allows us to sleep for exactly one interval of the current timer resolution.
This allows us to take advantage of systems that have a timer resolution of 0.5ms to reduce CPU overhead in the event loop.
2023-03-05 02:36:31 -05:00

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3.1 KiB
C++

// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "common/steady_clock.h"
#include "common/uint128.h"
#include "common/wall_clock.h"
#ifdef ARCHITECTURE_x86_64
#include "common/x64/cpu_detect.h"
#include "common/x64/native_clock.h"
#endif
namespace Common {
class StandardWallClock final : public WallClock {
public:
explicit StandardWallClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_)
: WallClock{emulated_cpu_frequency_, emulated_clock_frequency_, false},
start_time{SteadyClock::Now()} {}
std::chrono::nanoseconds GetTimeNS() override {
return SteadyClock::Now() - start_time;
}
std::chrono::microseconds GetTimeUS() override {
return std::chrono::duration_cast<std::chrono::microseconds>(GetTimeNS());
}
std::chrono::milliseconds GetTimeMS() override {
return std::chrono::duration_cast<std::chrono::milliseconds>(GetTimeNS());
}
u64 GetClockCycles() override {
const u128 temp = Common::Multiply64Into128(GetTimeNS().count(), emulated_clock_frequency);
return Common::Divide128On32(temp, NS_RATIO).first;
}
u64 GetCPUCycles() override {
const u128 temp = Common::Multiply64Into128(GetTimeNS().count(), emulated_cpu_frequency);
return Common::Divide128On32(temp, NS_RATIO).first;
}
void Pause([[maybe_unused]] bool is_paused) override {
// Do nothing in this clock type.
}
private:
SteadyClock::time_point start_time;
};
#ifdef ARCHITECTURE_x86_64
std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
u64 emulated_clock_frequency) {
const auto& caps = GetCPUCaps();
u64 rtsc_frequency = 0;
if (caps.invariant_tsc) {
rtsc_frequency = caps.tsc_frequency ? caps.tsc_frequency : EstimateRDTSCFrequency();
}
// Fallback to StandardWallClock if the hardware TSC does not have the precision greater than:
// - A nanosecond
// - The emulated CPU frequency
// - The emulated clock counter frequency (CNTFRQ)
if (rtsc_frequency <= WallClock::NS_RATIO || rtsc_frequency <= emulated_cpu_frequency ||
rtsc_frequency <= emulated_clock_frequency) {
return std::make_unique<StandardWallClock>(emulated_cpu_frequency,
emulated_clock_frequency);
} else {
return std::make_unique<X64::NativeClock>(emulated_cpu_frequency, emulated_clock_frequency,
rtsc_frequency);
}
}
#else
std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
u64 emulated_clock_frequency) {
return std::make_unique<StandardWallClock>(emulated_cpu_frequency, emulated_clock_frequency);
}
#endif
std::unique_ptr<WallClock> CreateStandardWallClock(u64 emulated_cpu_frequency,
u64 emulated_clock_frequency) {
return std::make_unique<StandardWallClock>(emulated_cpu_frequency, emulated_clock_frequency);
}
} // namespace Common