Merge pull request #10086 from Morph1984/coretiming-ng-1

core_timing: Use CNTPCT as the guest CPU tick

src/audio_core/renderer/adsp/adsp.cpp

@@ -7,7 +7,6 @@
 #include "common/logging/log.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 #include "core/memory.h"
 
 namespace AudioCore::AudioRenderer::ADSP {

src/audio_core/renderer/adsp/audio_renderer.cpp

@@ -13,7 +13,6 @@
 #include "common/thread.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 
 MICROPROFILE_DEFINE(Audio_Renderer, "Audio", "DSP", MP_RGB(60, 19, 97));
 
@@ -144,6 +143,7 @@ void AudioRenderer::ThreadFunc(std::stop_token stop_token) {
 
     mailbox->ADSPSendMessage(RenderMessage::AudioRenderer_InitializeOK);
 
+    // 0.12 seconds (2304000 / 19200000)
     constexpr u64 max_process_time{2'304'000ULL};
 
     while (!stop_token.stop_requested()) {
@@ -184,8 +184,7 @@ void AudioRenderer::ThreadFunc(std::stop_token stop_token) {
                     u64 max_time{max_process_time};
                     if (index == 1 && command_buffer.applet_resource_user_id ==
                                           mailbox->GetCommandBuffer(0).applet_resource_user_id) {
-                        max_time = max_process_time -
-                                   Core::Timing::CyclesToNs(render_times_taken[0]).count();
+                        max_time = max_process_time - render_times_taken[0];
                         if (render_times_taken[0] > max_process_time) {
                             max_time = 0;
                         }

src/audio_core/renderer/adsp/command_list_processor.cpp

@@ -9,7 +9,6 @@
 #include "common/settings.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 #include "core/memory.h"
 
 namespace AudioCore::AudioRenderer::ADSP {

src/audio_core/renderer/command/performance/performance.cpp

@@ -5,7 +5,6 @@
 #include "audio_core/renderer/command/performance/performance.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 
 namespace AudioCore::AudioRenderer {
 
@@ -18,20 +17,18 @@ void PerformanceCommand::Process(const ADSP::CommandListProcessor& processor) {
     auto base{entry_address.translated_address};
     if (state == PerformanceState::Start) {
         auto start_time_ptr{reinterpret_cast<u32*>(base + entry_address.entry_start_time_offset)};
-        *start_time_ptr = static_cast<u32>(
-            Core::Timing::CyclesToUs(processor.system->CoreTiming().GetClockTicks() -
-                                     processor.start_time - processor.current_processing_time)
-                .count());
+        *start_time_ptr =
+            static_cast<u32>(processor.system->CoreTiming().GetClockTicks() - processor.start_time -
+                             processor.current_processing_time);
     } else if (state == PerformanceState::Stop) {
         auto processed_time_ptr{
             reinterpret_cast<u32*>(base + entry_address.entry_processed_time_offset)};
         auto entry_count_ptr{
             reinterpret_cast<u32*>(base + entry_address.header_entry_count_offset)};
 
-        *processed_time_ptr = static_cast<u32>(
-            Core::Timing::CyclesToUs(processor.system->CoreTiming().GetClockTicks() -
-                                     processor.start_time - processor.current_processing_time)
-                .count());
+        *processed_time_ptr =
+            static_cast<u32>(processor.system->CoreTiming().GetClockTicks() - processor.start_time -
+                             processor.current_processing_time);
         (*entry_count_ptr)++;
     }
 }

src/audio_core/sink/sink_stream.cpp

@@ -15,7 +15,6 @@
 #include "common/settings.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 
 namespace AudioCore::Sink {
 

src/common/CMakeLists.txt

@@ -172,6 +172,8 @@ if(ARCHITECTURE_x86_64)
             x64/cpu_wait.h
             x64/native_clock.cpp
             x64/native_clock.h
+            x64/rdtsc.cpp
+            x64/rdtsc.h
             x64/xbyak_abi.h
             x64/xbyak_util.h
     )

src/common/steady_clock.cpp

@@ -28,13 +28,12 @@ static s64 GetSystemTimeNS() {
     // GetSystemTimePreciseAsFileTime returns the file time in 100ns units.
     static constexpr s64 Multiplier = 100;
     // Convert Windows epoch to Unix epoch.
-    static constexpr s64 WindowsEpochToUnixEpochNS = 0x19DB1DED53E8000LL;
+    static constexpr s64 WindowsEpochToUnixEpoch = 0x19DB1DED53E8000LL;
 
     FILETIME filetime;
     GetSystemTimePreciseAsFileTime(&filetime);
     return Multiplier * ((static_cast<s64>(filetime.dwHighDateTime) << 32) +
-                         static_cast<s64>(filetime.dwLowDateTime)) -
-           WindowsEpochToUnixEpochNS;
+                         static_cast<s64>(filetime.dwLowDateTime) - WindowsEpochToUnixEpoch);
 }
 #endif
 

src/common/wall_clock.cpp

@@ -2,88 +2,75 @@
 // 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"
+#include "common/x64/rdtsc.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()} {}
+    explicit StandardWallClock() : start_time{SteadyClock::Now()} {}
 
-    std::chrono::nanoseconds GetTimeNS() override {
+    std::chrono::nanoseconds GetTimeNS() const override {
         return SteadyClock::Now() - start_time;
     }
 
-    std::chrono::microseconds GetTimeUS() override {
-        return std::chrono::duration_cast<std::chrono::microseconds>(GetTimeNS());
+    std::chrono::microseconds GetTimeUS() const override {
+        return static_cast<std::chrono::microseconds>(GetHostTicksElapsed() / NsToUsRatio::den);
     }
 
-    std::chrono::milliseconds GetTimeMS() override {
-        return std::chrono::duration_cast<std::chrono::milliseconds>(GetTimeNS());
+    std::chrono::milliseconds GetTimeMS() const override {
+        return static_cast<std::chrono::milliseconds>(GetHostTicksElapsed() / NsToMsRatio::den);
     }
 
-    u64 GetClockCycles() override {
-        const u128 temp = Common::Multiply64Into128(GetTimeNS().count(), emulated_clock_frequency);
-        return Common::Divide128On32(temp, NS_RATIO).first;
+    u64 GetCNTPCT() const override {
+        return GetHostTicksElapsed() * NsToCNTPCTRatio::num / NsToCNTPCTRatio::den;
     }
 
-    u64 GetCPUCycles() override {
-        const u128 temp = Common::Multiply64Into128(GetTimeNS().count(), emulated_cpu_frequency);
-        return Common::Divide128On32(temp, NS_RATIO).first;
+    u64 GetGPUTick() const override {
+        return GetHostTicksElapsed() * NsToGPUTickRatio::num / NsToGPUTickRatio::den;
     }
 
-    void Pause([[maybe_unused]] bool is_paused) override {
-        // Do nothing in this clock type.
+    u64 GetHostTicksNow() const override {
+        return static_cast<u64>(SteadyClock::Now().time_since_epoch().count());
+    }
+
+    u64 GetHostTicksElapsed() const override {
+        return static_cast<u64>(GetTimeNS().count());
+    }
+
+    bool IsNative() const override {
+        return false;
     }
 
 private:
     SteadyClock::time_point start_time;
 };
 
+std::unique_ptr<WallClock> CreateOptimalClock() {
 #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);
+    if (caps.invariant_tsc && caps.tsc_frequency >= WallClock::GPUTickFreq) {
+        return std::make_unique<X64::NativeClock>(caps.tsc_frequency);
     } else {
-        return std::make_unique<X64::NativeClock>(emulated_cpu_frequency, emulated_clock_frequency,
-                                                  rtsc_frequency);
+        // Fallback to StandardWallClock if the hardware TSC
+        // - Is not invariant
+        // - Is not more precise than GPUTickFreq
+        return std::make_unique<StandardWallClock>();
     }
-}
-
 #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);
-}
-
+    return std::make_unique<StandardWallClock>();
 #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);
+std::unique_ptr<WallClock> CreateStandardWallClock() {
+    return std::make_unique<StandardWallClock>();
 }
 
 } // namespace Common

src/common/wall_clock.h

@@ -5,6 +5,7 @@
 
 #include <chrono>
 #include <memory>
+#include <ratio>
 
 #include "common/common_types.h"
 
@@ -12,50 +13,82 @@ namespace Common {
 
 class WallClock {
 public:
-    static constexpr u64 NS_RATIO = 1'000'000'000;
-    static constexpr u64 US_RATIO = 1'000'000;
-    static constexpr u64 MS_RATIO = 1'000;
+    static constexpr u64 CNTFRQ = 19'200'000;         // CNTPCT_EL0 Frequency = 19.2 MHz
+    static constexpr u64 GPUTickFreq = 614'400'000;   // GM20B GPU Tick Frequency = 614.4 MHz
+    static constexpr u64 CPUTickFreq = 1'020'000'000; // T210/4 A57 CPU Tick Frequency = 1020.0 MHz
 
     virtual ~WallClock() = default;
 
-    /// Returns current wall time in nanoseconds
-    [[nodiscard]] virtual std::chrono::nanoseconds GetTimeNS() = 0;
+    /// @returns The time in nanoseconds since the construction of this clock.
+    virtual std::chrono::nanoseconds GetTimeNS() const = 0;
 
-    /// Returns current wall time in microseconds
-    [[nodiscard]] virtual std::chrono::microseconds GetTimeUS() = 0;
+    /// @returns The time in microseconds since the construction of this clock.
+    virtual std::chrono::microseconds GetTimeUS() const = 0;
 
-    /// Returns current wall time in milliseconds
-    [[nodiscard]] virtual std::chrono::milliseconds GetTimeMS() = 0;
+    /// @returns The time in milliseconds since the construction of this clock.
+    virtual std::chrono::milliseconds GetTimeMS() const = 0;
 
-    /// Returns current wall time in emulated clock cycles
-    [[nodiscard]] virtual u64 GetClockCycles() = 0;
+    /// @returns The guest CNTPCT ticks since the construction of this clock.
+    virtual u64 GetCNTPCT() const = 0;
 
-    /// Returns current wall time in emulated cpu cycles
-    [[nodiscard]] virtual u64 GetCPUCycles() = 0;
+    /// @returns The guest GPU ticks since the construction of this clock.
+    virtual u64 GetGPUTick() const = 0;
 
-    virtual void Pause(bool is_paused) = 0;
+    /// @returns The raw host timer ticks since an indeterminate epoch.
+    virtual u64 GetHostTicksNow() const = 0;
 
-    /// Tells if the wall clock, uses the host CPU's hardware clock
-    [[nodiscard]] bool IsNative() const {
-        return is_native;
+    /// @returns The raw host timer ticks since the construction of this clock.
+    virtual u64 GetHostTicksElapsed() const = 0;
+
+    /// @returns Whether the clock directly uses the host's hardware clock.
+    virtual bool IsNative() const = 0;
+
+    static inline u64 NSToCNTPCT(u64 ns) {
+        return ns * NsToCNTPCTRatio::num / NsToCNTPCTRatio::den;
+    }
+
+    static inline u64 NSToGPUTick(u64 ns) {
+        return ns * NsToGPUTickRatio::num / NsToGPUTickRatio::den;
+    }
+
+    // Cycle Timing
+
+    static inline u64 CPUTickToNS(u64 cpu_tick) {
+        return cpu_tick * CPUTickToNsRatio::num / CPUTickToNsRatio::den;
+    }
+
+    static inline u64 CPUTickToUS(u64 cpu_tick) {
+        return cpu_tick * CPUTickToUsRatio::num / CPUTickToUsRatio::den;
+    }
+
+    static inline u64 CPUTickToCNTPCT(u64 cpu_tick) {
+        return cpu_tick * CPUTickToCNTPCTRatio::num / CPUTickToCNTPCTRatio::den;
+    }
+
+    static inline u64 CPUTickToGPUTick(u64 cpu_tick) {
+        return cpu_tick * CPUTickToGPUTickRatio::num / CPUTickToGPUTickRatio::den;
     }
 
 protected:
-    explicit WallClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_, bool is_native_)
-        : emulated_cpu_frequency{emulated_cpu_frequency_},
-          emulated_clock_frequency{emulated_clock_frequency_}, is_native{is_native_} {}
+    using NsRatio = std::nano;
+    using UsRatio = std::micro;
+    using MsRatio = std::milli;
+
+    using NsToUsRatio = std::ratio_divide<std::nano, std::micro>;
+    using NsToMsRatio = std::ratio_divide<std::nano, std::milli>;
+    using NsToCNTPCTRatio = std::ratio<CNTFRQ, std::nano::den>;
+    using NsToGPUTickRatio = std::ratio<GPUTickFreq, std::nano::den>;
 
-    u64 emulated_cpu_frequency;
-    u64 emulated_clock_frequency;
+    // Cycle Timing
 
-private:
-    bool is_native;
+    using CPUTickToNsRatio = std::ratio<std::nano::den, CPUTickFreq>;
+    using CPUTickToUsRatio = std::ratio<std::micro::den, CPUTickFreq>;
+    using CPUTickToCNTPCTRatio = std::ratio<CNTFRQ, CPUTickFreq>;
+    using CPUTickToGPUTickRatio = std::ratio<GPUTickFreq, CPUTickFreq>;
 };
 
-[[nodiscard]] std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
-                                                                 u64 emulated_clock_frequency);
+std::unique_ptr<WallClock> CreateOptimalClock();
 
-[[nodiscard]] std::unique_ptr<WallClock> CreateStandardWallClock(u64 emulated_cpu_frequency,
-                                                                 u64 emulated_clock_frequency);
+std::unique_ptr<WallClock> CreateStandardWallClock();
 
 } // namespace Common

src/common/x64/cpu_detect.cpp

@@ -14,6 +14,7 @@
 #include "common/common_types.h"
 #include "common/logging/log.h"
 #include "common/x64/cpu_detect.h"
+#include "common/x64/rdtsc.h"
 
 #ifdef _WIN32
 #include <windows.h>
@@ -187,6 +188,8 @@ static CPUCaps Detect() {
             caps.tsc_frequency = static_cast<u64>(caps.crystal_frequency) *
                                  caps.tsc_crystal_ratio_numerator /
                                  caps.tsc_crystal_ratio_denominator;
+        } else {
+            caps.tsc_frequency = X64::EstimateRDTSCFrequency();
         }
     }
 

src/common/x64/cpu_wait.cpp

@@ -9,19 +9,11 @@
 
 #include "common/x64/cpu_detect.h"
 #include "common/x64/cpu_wait.h"
+#include "common/x64/rdtsc.h"
 
 namespace Common::X64 {
 
 #ifdef _MSC_VER
-__forceinline static u64 FencedRDTSC() {
-    _mm_lfence();
-    _ReadWriteBarrier();
-    const u64 result = __rdtsc();
-    _mm_lfence();
-    _ReadWriteBarrier();
-    return result;
-}
-
 __forceinline static void TPAUSE() {
     // 100,000 cycles is a reasonable amount of time to wait to save on CPU resources.
     // For reference:
@@ -32,16 +24,6 @@ __forceinline static void TPAUSE() {
     _tpause(0, FencedRDTSC() + PauseCycles);
 }
 #else
-static u64 FencedRDTSC() {
-    u64 eax;
-    u64 edx;
-    asm volatile("lfence\n\t"
-                 "rdtsc\n\t"
-                 "lfence\n\t"
-                 : "=a"(eax), "=d"(edx));
-    return (edx << 32) | eax;
-}
-
 static void TPAUSE() {
     // 100,000 cycles is a reasonable amount of time to wait to save on CPU resources.
     // For reference:

src/common/x64/native_clock.cpp

@@ -1,164 +1,50 @@
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-#include <array>
-#include <chrono>
-#include <thread>
-
-#include "common/atomic_ops.h"
-#include "common/steady_clock.h"
 #include "common/uint128.h"
 #include "common/x64/native_clock.h"
+#include "common/x64/rdtsc.h"
 
-#ifdef _MSC_VER
-#include <intrin.h>
-#endif
-
-namespace Common {
+namespace Common::X64 {
 
-#ifdef _MSC_VER
-__forceinline static u64 FencedRDTSC() {
-    _mm_lfence();
-    _ReadWriteBarrier();
-    const u64 result = __rdtsc();
-    _mm_lfence();
-    _ReadWriteBarrier();
-    return result;
-}
-#else
-static u64 FencedRDTSC() {
-    u64 eax;
-    u64 edx;
-    asm volatile("lfence\n\t"
-                 "rdtsc\n\t"
-                 "lfence\n\t"
-                 : "=a"(eax), "=d"(edx));
-    return (edx << 32) | eax;
-}
-#endif
+NativeClock::NativeClock(u64 rdtsc_frequency_)
+    : start_ticks{FencedRDTSC()}, rdtsc_frequency{rdtsc_frequency_},
+      ns_rdtsc_factor{GetFixedPoint64Factor(NsRatio::den, rdtsc_frequency)},
+      us_rdtsc_factor{GetFixedPoint64Factor(UsRatio::den, rdtsc_frequency)},
+      ms_rdtsc_factor{GetFixedPoint64Factor(MsRatio::den, rdtsc_frequency)},
+      cntpct_rdtsc_factor{GetFixedPoint64Factor(CNTFRQ, rdtsc_frequency)},
+      gputick_rdtsc_factor{GetFixedPoint64Factor(GPUTickFreq, rdtsc_frequency)} {}
 
-template <u64 Nearest>
-static u64 RoundToNearest(u64 value) {
-    const auto mod = value % Nearest;
-    return mod >= (Nearest / 2) ? (value - mod + Nearest) : (value - mod);
+std::chrono::nanoseconds NativeClock::GetTimeNS() const {
+    return std::chrono::nanoseconds{MultiplyHigh(GetHostTicksElapsed(), ns_rdtsc_factor)};
 }
 
-u64 EstimateRDTSCFrequency() {
-    // Discard the first result measuring the rdtsc.
-    FencedRDTSC();
-    std::this_thread::sleep_for(std::chrono::milliseconds{1});
-    FencedRDTSC();
-
-    // Get the current time.
-    const auto start_time = Common::RealTimeClock::Now();
-    const u64 tsc_start = FencedRDTSC();
-    // Wait for 250 milliseconds.
-    std::this_thread::sleep_for(std::chrono::milliseconds{250});
-    const auto end_time = Common::RealTimeClock::Now();
-    const u64 tsc_end = FencedRDTSC();
-    // Calculate differences.
-    const u64 timer_diff = static_cast<u64>(
-        std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count());
-    const u64 tsc_diff = tsc_end - tsc_start;
-    const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
-    return RoundToNearest<1000>(tsc_freq);
+std::chrono::microseconds NativeClock::GetTimeUS() const {
+    return std::chrono::microseconds{MultiplyHigh(GetHostTicksElapsed(), us_rdtsc_factor)};
 }
 
-namespace X64 {
-NativeClock::NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_,
-                         u64 rtsc_frequency_)
-    : WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, true), rtsc_frequency{
-                                                                               rtsc_frequency_} {
-    // Thread to re-adjust the RDTSC frequency after 10 seconds has elapsed.
-    time_sync_thread = std::jthread{[this](std::stop_token token) {
-        // Get the current time.
-        const auto start_time = Common::RealTimeClock::Now();
-        const u64 tsc_start = FencedRDTSC();
-        // Wait for 10 seconds.
-        if (!Common::StoppableTimedWait(token, std::chrono::seconds{10})) {
-            return;
-        }
-        const auto end_time = Common::RealTimeClock::Now();
-        const u64 tsc_end = FencedRDTSC();
-        // Calculate differences.
-        const u64 timer_diff = static_cast<u64>(
-            std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count());
-        const u64 tsc_diff = tsc_end - tsc_start;
-        const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
-        rtsc_frequency = tsc_freq;
-        CalculateAndSetFactors();
-    }};
-
-    time_point.inner.last_measure = FencedRDTSC();
-    time_point.inner.accumulated_ticks = 0U;
-    CalculateAndSetFactors();
+std::chrono::milliseconds NativeClock::GetTimeMS() const {
+    return std::chrono::milliseconds{MultiplyHigh(GetHostTicksElapsed(), ms_rdtsc_factor)};
 }
 
-u64 NativeClock::GetRTSC() {
-    TimePoint new_time_point{};
-    TimePoint current_time_point{};
-
-    current_time_point.pack = Common::AtomicLoad128(time_point.pack.data());
-    do {
-        const u64 current_measure = FencedRDTSC();
-        u64 diff = current_measure - current_time_point.inner.last_measure;
-        diff = diff & ~static_cast<u64>(static_cast<s64>(diff) >> 63); // max(diff, 0)
-        new_time_point.inner.last_measure = current_measure > current_time_point.inner.last_measure
-                                                ? current_measure
-                                                : current_time_point.inner.last_measure;
-        new_time_point.inner.accumulated_ticks = current_time_point.inner.accumulated_ticks + diff;
-    } while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack,
-                                           current_time_point.pack, current_time_point.pack));
-    return new_time_point.inner.accumulated_ticks;
+u64 NativeClock::GetCNTPCT() const {
+    return MultiplyHigh(GetHostTicksElapsed(), cntpct_rdtsc_factor);
 }
 
-void NativeClock::Pause(bool is_paused) {
-    if (!is_paused) {
-        TimePoint current_time_point{};
-        TimePoint new_time_point{};
-
-        current_time_point.pack = Common::AtomicLoad128(time_point.pack.data());
-        do {
-            new_time_point.pack = current_time_point.pack;
-            new_time_point.inner.last_measure = FencedRDTSC();
-        } while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack,
-                                               current_time_point.pack, current_time_point.pack));
-    }
+u64 NativeClock::GetGPUTick() const {
+    return MultiplyHigh(GetHostTicksElapsed(), gputick_rdtsc_factor);
 }
 
-std::chrono::nanoseconds NativeClock::GetTimeNS() {
-    const u64 rtsc_value = GetRTSC();
-    return std::chrono::nanoseconds{MultiplyHigh(rtsc_value, ns_rtsc_factor)};
+u64 NativeClock::GetHostTicksNow() const {
+    return FencedRDTSC();
 }
 
-std::chrono::microseconds NativeClock::GetTimeUS() {
-    const u64 rtsc_value = GetRTSC();
-    return std::chrono::microseconds{MultiplyHigh(rtsc_value, us_rtsc_factor)};
+u64 NativeClock::GetHostTicksElapsed() const {
+    return FencedRDTSC() - start_ticks;
 }
 
-std::chrono::milliseconds NativeClock::GetTimeMS() {
-    const u64 rtsc_value = GetRTSC();
-    return std::chrono::milliseconds{MultiplyHigh(rtsc_value, ms_rtsc_factor)};
+bool NativeClock::IsNative() const {
+    return true;
 }
 
-u64 NativeClock::GetClockCycles() {
-    const u64 rtsc_value = GetRTSC();
-    return MultiplyHigh(rtsc_value, clock_rtsc_factor);
-}
-
-u64 NativeClock::GetCPUCycles() {
-    const u64 rtsc_value = GetRTSC();
-    return MultiplyHigh(rtsc_value, cpu_rtsc_factor);
-}
-
-void NativeClock::CalculateAndSetFactors() {
-    ns_rtsc_factor = GetFixedPoint64Factor(NS_RATIO, rtsc_frequency);
-    us_rtsc_factor = GetFixedPoint64Factor(US_RATIO, rtsc_frequency);
-    ms_rtsc_factor = GetFixedPoint64Factor(MS_RATIO, rtsc_frequency);
-    clock_rtsc_factor = GetFixedPoint64Factor(emulated_clock_frequency, rtsc_frequency);
-    cpu_rtsc_factor = GetFixedPoint64Factor(emulated_cpu_frequency, rtsc_frequency);
-}
-
-} // namespace X64
-
-} // namespace Common
+} // namespace Common::X64

src/common/x64/native_clock.h

@@ -3,58 +3,39 @@
 
 #pragma once
 
-#include "common/polyfill_thread.h"
 #include "common/wall_clock.h"
 
-namespace Common {
+namespace Common::X64 {
 
-namespace X64 {
 class NativeClock final : public WallClock {
 public:
-    explicit NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_,
-                         u64 rtsc_frequency_);
+    explicit NativeClock(u64 rdtsc_frequency_);
 
-    std::chrono::nanoseconds GetTimeNS() override;
+    std::chrono::nanoseconds GetTimeNS() const override;
 
-    std::chrono::microseconds GetTimeUS() override;
+    std::chrono::microseconds GetTimeUS() const override;
 
-    std::chrono::milliseconds GetTimeMS() override;
+    std::chrono::milliseconds GetTimeMS() const override;
 
-    u64 GetClockCycles() override;
+    u64 GetCNTPCT() const override;
 
-    u64 GetCPUCycles() override;
+    u64 GetGPUTick() const override;
 
-    void Pause(bool is_paused) override;
+    u64 GetHostTicksNow() const override;
 
-private:
-    u64 GetRTSC();
-
-    void CalculateAndSetFactors();
-
-    union alignas(16) TimePoint {
-        TimePoint() : pack{} {}
-        u128 pack{};
-        struct Inner {
-            u64 last_measure{};
-            u64 accumulated_ticks{};
-        } inner;
-    };
-
-    TimePoint time_point;
+    u64 GetHostTicksElapsed() const override;
 
-    // factors
-    u64 clock_rtsc_factor{};
-    u64 cpu_rtsc_factor{};
-    u64 ns_rtsc_factor{};
-    u64 us_rtsc_factor{};
-    u64 ms_rtsc_factor{};
+    bool IsNative() const override;
 
-    u64 rtsc_frequency;
-
-    std::jthread time_sync_thread;
+private:
+    u64 start_ticks;
+    u64 rdtsc_frequency;
+
+    u64 ns_rdtsc_factor;
+    u64 us_rdtsc_factor;
+    u64 ms_rdtsc_factor;
+    u64 cntpct_rdtsc_factor;
+    u64 gputick_rdtsc_factor;
 };
-} // namespace X64
-
-u64 EstimateRDTSCFrequency();
 
-} // namespace Common
+} // namespace Common::X64

src/common/x64/rdtsc.cpp

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <thread>
+
+#include "common/steady_clock.h"
+#include "common/uint128.h"
+#include "common/x64/rdtsc.h"
+
+namespace Common::X64 {
+
+template <u64 Nearest>
+static u64 RoundToNearest(u64 value) {
+    const auto mod = value % Nearest;
+    return mod >= (Nearest / 2) ? (value - mod + Nearest) : (value - mod);
+}
+
+u64 EstimateRDTSCFrequency() {
+    // Discard the first result measuring the rdtsc.
+    FencedRDTSC();
+    std::this_thread::sleep_for(std::chrono::milliseconds{1});
+    FencedRDTSC();
+
+    // Get the current time.
+    const auto start_time = RealTimeClock::Now();
+    const u64 tsc_start = FencedRDTSC();
+    // Wait for 100 milliseconds.
+    std::this_thread::sleep_for(std::chrono::milliseconds{100});
+    const auto end_time = RealTimeClock::Now();
+    const u64 tsc_end = FencedRDTSC();
+    // Calculate differences.
+    const u64 timer_diff = static_cast<u64>(
+        std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count());
+    const u64 tsc_diff = tsc_end - tsc_start;
+    const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
+    return RoundToNearest<100'000>(tsc_freq);
+}
+
+} // namespace Common::X64

src/common/x64/rdtsc.h

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#endif
+
+#include "common/common_types.h"
+
+namespace Common::X64 {
+
+#ifdef _MSC_VER
+__forceinline static u64 FencedRDTSC() {
+    _mm_lfence();
+    _ReadWriteBarrier();
+    const u64 result = __rdtsc();
+    _mm_lfence();
+    _ReadWriteBarrier();
+    return result;
+}
+#else
+static inline u64 FencedRDTSC() {
+    u64 eax;
+    u64 edx;
+    asm volatile("lfence\n\t"
+                 "rdtsc\n\t"
+                 "lfence\n\t"
+                 : "=a"(eax), "=d"(edx));
+    return (edx << 32) | eax;
+}
+#endif
+
+u64 EstimateRDTSCFrequency();
+
+} // namespace Common::X64

src/core/CMakeLists.txt

@@ -14,7 +14,6 @@ add_library(core STATIC
     core.h
     core_timing.cpp
     core_timing.h
-    core_timing_util.h
     cpu_manager.cpp
     cpu_manager.h
     crypto/aes_util.cpp

src/core/core_timing.cpp

@@ -16,12 +16,11 @@
 
 #include "common/microprofile.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 #include "core/hardware_properties.h"
 
 namespace Core::Timing {
 
-constexpr s64 MAX_SLICE_LENGTH = 4000;
+constexpr s64 MAX_SLICE_LENGTH = 10000;
 
 std::shared_ptr<EventType> CreateEvent(std::string name, TimedCallback&& callback) {
     return std::make_shared<EventType>(std::move(callback), std::move(name));
@@ -45,9 +44,7 @@ struct CoreTiming::Event {
     }
 };
 
-CoreTiming::CoreTiming()
-    : cpu_clock{Common::CreateBestMatchingClock(Hardware::BASE_CLOCK_RATE, Hardware::CNTFREQ)},
-      event_clock{Common::CreateStandardWallClock(Hardware::BASE_CLOCK_RATE, Hardware::CNTFREQ)} {}
+CoreTiming::CoreTiming() : clock{Common::CreateOptimalClock()} {}
 
 CoreTiming::~CoreTiming() {
     Reset();
@@ -68,7 +65,7 @@ void CoreTiming::Initialize(std::function<void()>&& on_thread_init_) {
     on_thread_init = std::move(on_thread_init_);
     event_fifo_id = 0;
     shutting_down = false;
-    ticks = 0;
+    cpu_ticks = 0;
     const auto empty_timed_callback = [](std::uintptr_t, u64, std::chrono::nanoseconds)
         -> std::optional<std::chrono::nanoseconds> { return std::nullopt; };
     ev_lost = CreateEvent("_lost_event", empty_timed_callback);
@@ -173,38 +170,30 @@ void CoreTiming::UnscheduleEvent(const std::shared_ptr<EventType>& event_type,
 }
 
 void CoreTiming::AddTicks(u64 ticks_to_add) {
-    ticks += ticks_to_add;
-    downcount -= static_cast<s64>(ticks);
+    cpu_ticks += ticks_to_add;
+    downcount -= static_cast<s64>(cpu_ticks);
 }
 
 void CoreTiming::Idle() {
-    if (!event_queue.empty()) {
-        const u64 next_event_time = event_queue.front().time;
-        const u64 next_ticks = nsToCycles(std::chrono::nanoseconds(next_event_time)) + 10U;
-        if (next_ticks > ticks) {
-            ticks = next_ticks;
-        }
-        return;
-    }
-    ticks += 1000U;
+    cpu_ticks += 1000U;
 }
 
 void CoreTiming::ResetTicks() {
     downcount = MAX_SLICE_LENGTH;
 }
 
-u64 CoreTiming::GetCPUTicks() const {
+u64 CoreTiming::GetClockTicks() const {
     if (is_multicore) [[likely]] {
-        return cpu_clock->GetCPUCycles();
+        return clock->GetCNTPCT();
     }
-    return ticks;
+    return Common::WallClock::CPUTickToCNTPCT(cpu_ticks);
 }
 
-u64 CoreTiming::GetClockTicks() const {
+u64 CoreTiming::GetGPUTicks() const {
     if (is_multicore) [[likely]] {
-        return cpu_clock->GetClockCycles();
+        return clock->GetGPUTick();
     }
-    return CpuCyclesToClockCycles(ticks);
+    return Common::WallClock::CPUTickToGPUTick(cpu_ticks);
 }
 
 std::optional<s64> CoreTiming::Advance() {
@@ -297,9 +286,7 @@ void CoreTiming::ThreadLoop() {
         }
 
         paused_set = true;
-        event_clock->Pause(true);
         pause_event.Wait();
-        event_clock->Pause(false);
     }
 }
 
@@ -315,25 +302,18 @@ void CoreTiming::Reset() {
     has_started = false;
 }
 
-std::chrono::nanoseconds CoreTiming::GetCPUTimeNs() const {
-    if (is_multicore) [[likely]] {
-        return cpu_clock->GetTimeNS();
-    }
-    return CyclesToNs(ticks);
-}
-
 std::chrono::nanoseconds CoreTiming::GetGlobalTimeNs() const {
     if (is_multicore) [[likely]] {
-        return event_clock->GetTimeNS();
+        return clock->GetTimeNS();
     }
-    return CyclesToNs(ticks);
+    return std::chrono::nanoseconds{Common::WallClock::CPUTickToNS(cpu_ticks)};
 }
 
 std::chrono::microseconds CoreTiming::GetGlobalTimeUs() const {
     if (is_multicore) [[likely]] {
-        return event_clock->GetTimeUS();
+        return clock->GetTimeUS();
     }
-    return CyclesToUs(ticks);
+    return std::chrono::microseconds{Common::WallClock::CPUTickToUS(cpu_ticks)};
 }
 
 } // namespace Core::Timing

src/core/core_timing.h

@@ -116,14 +116,11 @@ public:
         return downcount;
     }
 
-    /// Returns current time in emulated CPU cycles
-    u64 GetCPUTicks() const;
-
-    /// Returns current time in emulated in Clock cycles
+    /// Returns the current CNTPCT tick value.
     u64 GetClockTicks() const;
 
-    /// Returns current time in nanoseconds.
-    std::chrono::nanoseconds GetCPUTimeNs() const;
+    /// Returns the current GPU tick value.
+    u64 GetGPUTicks() const;
 
     /// Returns current time in microseconds.
     std::chrono::microseconds GetGlobalTimeUs() const;
@@ -142,8 +139,7 @@ private:
 
     void Reset();
 
-    std::unique_ptr<Common::WallClock> cpu_clock;
-    std::unique_ptr<Common::WallClock> event_clock;
+    std::unique_ptr<Common::WallClock> clock;
 
     s64 global_timer = 0;
 
@@ -171,7 +167,7 @@ private:
     s64 pause_end_time{};
 
     /// Cycle timing
-    u64 ticks{};
+    u64 cpu_ticks{};
     s64 downcount{};
 };
 

src/core/core_timing_util.h

@@ -1,58 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#pragma once
-
-#include <chrono>
-
-#include "common/common_types.h"
-#include "core/hardware_properties.h"
-
-namespace Core::Timing {
-
-namespace detail {
-constexpr u64 CNTFREQ_ADJUSTED = Hardware::CNTFREQ / 1000;
-constexpr u64 BASE_CLOCK_RATE_ADJUSTED = Hardware::BASE_CLOCK_RATE / 1000;
-} // namespace detail
-
-[[nodiscard]] constexpr s64 msToCycles(std::chrono::milliseconds ms) {
-    return ms.count() * detail::BASE_CLOCK_RATE_ADJUSTED;
-}
-
-[[nodiscard]] constexpr s64 usToCycles(std::chrono::microseconds us) {
-    return us.count() * detail::BASE_CLOCK_RATE_ADJUSTED / 1000;
-}
-
-[[nodiscard]] constexpr s64 nsToCycles(std::chrono::nanoseconds ns) {
-    return ns.count() * detail::BASE_CLOCK_RATE_ADJUSTED / 1000000;
-}
-
-[[nodiscard]] constexpr u64 msToClockCycles(std::chrono::milliseconds ms) {
-    return static_cast<u64>(ms.count()) * detail::CNTFREQ_ADJUSTED;
-}
-
-[[nodiscard]] constexpr u64 usToClockCycles(std::chrono::microseconds us) {
-    return us.count() * detail::CNTFREQ_ADJUSTED / 1000;
-}
-
-[[nodiscard]] constexpr u64 nsToClockCycles(std::chrono::nanoseconds ns) {
-    return ns.count() * detail::CNTFREQ_ADJUSTED / 1000000;
-}
-
-[[nodiscard]] constexpr u64 CpuCyclesToClockCycles(u64 ticks) {
-    return ticks * detail::CNTFREQ_ADJUSTED / detail::BASE_CLOCK_RATE_ADJUSTED;
-}
-
-[[nodiscard]] constexpr std::chrono::milliseconds CyclesToMs(s64 cycles) {
-    return std::chrono::milliseconds(cycles / detail::BASE_CLOCK_RATE_ADJUSTED);
-}
-
-[[nodiscard]] constexpr std::chrono::nanoseconds CyclesToNs(s64 cycles) {
-    return std::chrono::nanoseconds(cycles * 1000000 / detail::BASE_CLOCK_RATE_ADJUSTED);
-}
-
-[[nodiscard]] constexpr std::chrono::microseconds CyclesToUs(s64 cycles) {
-    return std::chrono::microseconds(cycles * 1000 / detail::BASE_CLOCK_RATE_ADJUSTED);
-}
-
-} // namespace Core::Timing

src/core/hle/kernel/k_scheduler.cpp

@@ -184,7 +184,8 @@ u64 KScheduler::UpdateHighestPriorityThread(KThread* highest_thread) {
         prev_highest_thread != highest_thread) [[likely]] {
         if (prev_highest_thread != nullptr) [[likely]] {
             IncrementScheduledCount(prev_highest_thread);
-            prev_highest_thread->SetLastScheduledTick(m_kernel.System().CoreTiming().GetCPUTicks());
+            prev_highest_thread->SetLastScheduledTick(
+                m_kernel.System().CoreTiming().GetClockTicks());
         }
         if (m_state.should_count_idle) {
             if (highest_thread != nullptr) [[likely]] {
@@ -351,7 +352,7 @@ void KScheduler::SwitchThread(KThread* next_thread) {
 
     // Update the CPU time tracking variables.
     const s64 prev_tick = m_last_context_switch_time;
-    const s64 cur_tick = m_kernel.System().CoreTiming().GetCPUTicks();
+    const s64 cur_tick = m_kernel.System().CoreTiming().GetClockTicks();
     const s64 tick_diff = cur_tick - prev_tick;
     cur_thread->AddCpuTime(m_core_id, tick_diff);
     if (cur_process != nullptr) {

src/core/hle/kernel/svc/svc_info.cpp

@@ -199,9 +199,9 @@ Result GetInfo(Core::System& system, u64* result, InfoType info_id_type, Handle
         if (same_thread && info_sub_id == 0xFFFFFFFFFFFFFFFF) {
             const u64 thread_ticks = current_thread->GetCpuTime();
 
-            out_ticks = thread_ticks + (core_timing.GetCPUTicks() - prev_ctx_ticks);
+            out_ticks = thread_ticks + (core_timing.GetClockTicks() - prev_ctx_ticks);
         } else if (same_thread && info_sub_id == system.Kernel().CurrentPhysicalCoreIndex()) {
-            out_ticks = core_timing.GetCPUTicks() - prev_ctx_ticks;
+            out_ticks = core_timing.GetClockTicks() - prev_ctx_ticks;
         }
 
         *result = out_ticks;

src/core/hle/kernel/svc/svc_tick.cpp

@@ -12,16 +12,8 @@ namespace Kernel::Svc {
 int64_t GetSystemTick(Core::System& system) {
     LOG_TRACE(Kernel_SVC, "called");
 
-    auto& core_timing = system.CoreTiming();
-
     // Returns the value of cntpct_el0 (https://switchbrew.org/wiki/SVC#svcGetSystemTick)
-    const u64 result{core_timing.GetClockTicks()};
-
-    if (!system.Kernel().IsMulticore()) {
-        core_timing.AddTicks(400U);
-    }
-
-    return static_cast<int64_t>(result);
+    return static_cast<int64_t>(system.CoreTiming().GetClockTicks());
 }
 
 int64_t GetSystemTick64(Core::System& system) {

src/core/hle/service/hid/hidbus.cpp

@@ -5,7 +5,6 @@
 #include "common/settings.h"
 #include "core/core.h"
 #include "core/core_timing.h"
-#include "core/core_timing_util.h"
 #include "core/hid/hid_types.h"
 #include "core/hle/kernel/k_event.h"
 #include "core/hle/kernel/k_readable_event.h"

src/core/hle/service/nvdrv/devices/nvdisp_disp0.cpp

@@ -51,8 +51,8 @@ void nvdisp_disp0::flip(u32 buffer_handle, u32 offset, android::PixelFormat form
                                                stride, format, transform, crop_rect};
 
     system.GPU().RequestSwapBuffers(&framebuffer, fences, num_fences);
-    system.GetPerfStats().EndSystemFrame();
     system.SpeedLimiter().DoSpeedLimiting(system.CoreTiming().GetGlobalTimeUs());
+    system.GetPerfStats().EndSystemFrame();
     system.GetPerfStats().BeginSystemFrame();
 }
 

src/core/hle/service/nvnflinger/nvnflinger.cpp

@@ -70,7 +70,8 @@ Nvnflinger::Nvnflinger(Core::System& system_, HosBinderDriverServer& hos_binder_
         [this](std::uintptr_t, s64 time,
                std::chrono::nanoseconds ns_late) -> std::optional<std::chrono::nanoseconds> {
             vsync_signal.store(true);
-            vsync_signal.notify_all();
+            { const auto lock_guard = Lock(); }
+            vsync_signal.notify_one();
             return std::chrono::nanoseconds(GetNextTicks());
         });
 

src/core/hle/service/time/clock_types.h

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <ratio>
+
 #include "common/common_funcs.h"
 #include "common/common_types.h"
 #include "common/uuid.h"
@@ -74,18 +76,19 @@ static_assert(std::is_trivially_copyable_v<ContinuousAdjustmentTimePoint>,
 /// https://switchbrew.org/wiki/Glue_services#TimeSpanType
 struct TimeSpanType {
     s64 nanoseconds{};
-    static constexpr s64 ns_per_second{1000000000ULL};
 
     s64 ToSeconds() const {
-        return nanoseconds / ns_per_second;
+        return nanoseconds / std::nano::den;
     }
 
     static TimeSpanType FromSeconds(s64 seconds) {
-        return {seconds * ns_per_second};
+        return {seconds * std::nano::den};
     }
 
-    static TimeSpanType FromTicks(u64 ticks, u64 frequency) {
-        return FromSeconds(static_cast<s64>(ticks) / static_cast<s64>(frequency));
+    template <u64 Frequency>
+    static TimeSpanType FromTicks(u64 ticks) {
+        using TicksToNSRatio = std::ratio<std::nano::den, Frequency>;
+        return {static_cast<s64>(ticks * TicksToNSRatio::num / TicksToNSRatio::den)};
     }
 };
 static_assert(sizeof(TimeSpanType) == 8, "TimeSpanType is incorrect size");

src/core/hle/service/time/standard_steady_clock_core.cpp

@@ -10,7 +10,7 @@ namespace Service::Time::Clock {
 
 TimeSpanType StandardSteadyClockCore::GetCurrentRawTimePoint(Core::System& system) {
     const TimeSpanType ticks_time_span{
-        TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+        TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(system.CoreTiming().GetClockTicks())};
     TimeSpanType raw_time_point{setup_value.nanoseconds + ticks_time_span.nanoseconds};
 
     if (raw_time_point.nanoseconds < cached_raw_time_point.nanoseconds) {

src/core/hle/service/time/tick_based_steady_clock_core.cpp

@@ -10,7 +10,7 @@ namespace Service::Time::Clock {
 
 SteadyClockTimePoint TickBasedSteadyClockCore::GetTimePoint(Core::System& system) {
     const TimeSpanType ticks_time_span{
-        TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+        TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(system.CoreTiming().GetClockTicks())};
 
     return {ticks_time_span.ToSeconds(), GetClockSourceId()};
 }

src/core/hle/service/time/time.cpp

@@ -240,8 +240,8 @@ void Module::Interface::CalculateMonotonicSystemClockBaseTimePoint(HLERequestCon
     const auto current_time_point{steady_clock_core.GetCurrentTimePoint(system)};
 
     if (current_time_point.clock_source_id == context.steady_time_point.clock_source_id) {
-        const auto ticks{Clock::TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(),
-                                                        Core::Hardware::CNTFREQ)};
+        const auto ticks{Clock::TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(
+            system.CoreTiming().GetClockTicks())};
         const s64 base_time_point{context.offset + current_time_point.time_point -
                                   ticks.ToSeconds()};
         IPC::ResponseBuilder rb{ctx, (sizeof(s64) / 4) + 2};

src/core/hle/service/time/time_sharedmemory.cpp

@@ -21,8 +21,9 @@ SharedMemory::~SharedMemory() = default;
 
 void SharedMemory::SetupStandardSteadyClock(const Common::UUID& clock_source_id,
                                             Clock::TimeSpanType current_time_point) {
-    const Clock::TimeSpanType ticks_time_span{Clock::TimeSpanType::FromTicks(
-        system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+    const Clock::TimeSpanType ticks_time_span{
+        Clock::TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(
+            system.CoreTiming().GetClockTicks())};
     const Clock::SteadyClockContext context{
         static_cast<u64>(current_time_point.nanoseconds - ticks_time_span.nanoseconds),
         clock_source_id};

src/video_core/gpu.cpp

@@ -193,18 +193,13 @@ struct GPU::Impl {
     }
 
     [[nodiscard]] u64 GetTicks() const {
-        // This values were reversed engineered by fincs from NVN
-        // The gpu clock is reported in units of 385/625 nanoseconds
-        constexpr u64 gpu_ticks_num = 384;
-        constexpr u64 gpu_ticks_den = 625;
+        u64 gpu_tick = system.CoreTiming().GetGPUTicks();
 
-        u64 nanoseconds = system.CoreTiming().GetCPUTimeNs().count();
         if (Settings::values.use_fast_gpu_time.GetValue()) {
-            nanoseconds /= 256;
+            gpu_tick /= 256;
         }
-        const u64 nanoseconds_num = nanoseconds / gpu_ticks_den;
-        const u64 nanoseconds_rem = nanoseconds % gpu_ticks_den;
-        return nanoseconds_num * gpu_ticks_num + (nanoseconds_rem * gpu_ticks_num) / gpu_ticks_den;
+
+        return gpu_tick;
     }
 
     [[nodiscard]] bool IsAsync() const {