From 0218eacfd560d0ce48b3ffe64d279ee85bbf1347 Mon Sep 17 00:00:00 2001 From: Takoroka <137927095+Takoroka@users.noreply.github.com> Date: Fri, 30 Oct 2026 01:55:20 -0400 Subject: nx2: run the guest counter at 31.25 MHz for Switch 2 titles The Switch 2 counter runs at 31.25 MHz and its SDK converts ticks with that constant: Mario Kart World's sdk builds 31,250,000 in nn::os::GetSystemTickFrequency, TickManager::ConvertToTimeSpan and TickManager::ConvertToTick (19.2 MHz appears nowhere). Eglantine counted at the Switch 1 rate for every title, so every tick-based time in a Switch 2 game was off by 1.63x: elapsed times read short, and a deadline of one 60 Hz frame converted to ticks waited ~27 ms. The wall clock now has a guest counter frequency, set at boot: 31.25 MHz for Switch 2 programs, 19.2 MHz otherwise, EDEN_NX2_CNTFRQ= to force one. CNTPCT reads, CNTFRQ_EL0, svcGetSystemTick, thread tick counts and the time services' tick conversions follow it, and the CNTPCT spin detection keeps its ~1.7 us threshold. Mario Kart World, title screen and attract demo, 180 s, same build: frame times unchanged (17-19 ms once warm), process CPU time 848 s instead of 930 s. --- src/common/cpu_features.h | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'src/common/cpu_features.h') diff --git a/src/common/cpu_features.h b/src/common/cpu_features.h index 61aa2767ab..31be2dc956 100644 --- a/src/common/cpu_features.h +++ b/src/common/cpu_features.h @@ -7,6 +7,7 @@ #pragma once +#include #include #include #include @@ -20,11 +21,24 @@ namespace Common { class WallClock { public: static constexpr u64 CNTFRQ = 19'200'000; // CNTPCT_EL0 Frequency = 19.2 MHz + static constexpr u64 Switch2CNTFRQ = 31'250'000; // Switch 2 CNTPCT_EL0 Frequency = 31.25 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 explicit WallClock(bool invariant, u64 rdtsc_frequency_) noexcept; + /// Sets the guest counter's frequency: CNTFRQ, or Switch2CNTFRQ for Switch 2 titles (their SDK + /// converts ticks with a constant 31.25 MHz). Called at boot, before guest code runs. + void SetGuestCNTFRQ(u64 frequency); + + /// @returns The guest counter's frequency (CNTFRQ_EL0). + [[nodiscard]] u64 GetGuestCNTFRQ() const { + return guest_cntfrq.load(std::memory_order_relaxed); + } + + /// @returns Emulated CPU ticks (single core timing) as guest CNTPCT ticks. + [[nodiscard]] u64 CPUTickToGuestCNTPCT(u64 cpu_tick) const; + /// @returns The time in nanoseconds since the construction of this clock. std::chrono::nanoseconds GetTimeNS() const; @@ -34,7 +48,7 @@ public: /// @returns The time in milliseconds since the construction of this clock. std::chrono::milliseconds GetTimeMS() const; - /// @returns The guest CNTPCT ticks since the construction of this clock. + /// @returns The guest CNTPCT ticks (at GetGuestCNTFRQ()) since the construction of this clock. s64 GetCNTPCT() const; /// @returns The guest GPU ticks since the construction of this clock. @@ -91,6 +105,7 @@ public: using CPUTickToCNTPCTRatio = std::ratio; using CPUTickToGPUTickRatio = std::ratio; + std::atomic guest_cntfrq{CNTFRQ}; #if defined(ARCHITECTURE_x86_64) u64 rdtsc_frequency; u64 ns_rdtsc_factor; @@ -98,7 +113,7 @@ public: u64 ms_rdtsc_factor; u64 rdtsc_ns_integer; u64 rdtsc_ns_factor; - u64 cntpct_rdtsc_factor; + std::atomic cntpct_rdtsc_factor; u64 gputick_rdtsc_factor; bool invariant; #elif defined(HAS_NCE) @@ -106,6 +121,7 @@ public: [[nodiscard]] inline FactorType GetGuestCNTFRQFactor() const { return guest_cntfrq_factor; } + u64 host_cntfrq; FactorType ns_cntfrq_factor; FactorType us_cntfrq_factor; FactorType ms_cntfrq_factor; @@ -183,6 +199,6 @@ std::optional GetProcessorCount(); /// @brief Global cpu caps extern const CPUCaps g_cpu_caps; /// @brief Global wall clock -extern const WallClock g_wall_clock; +extern WallClock g_wall_clock; } // namespace Common -- cgit v1.2.3