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.cpp | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) (limited to 'src/common/cpu_features.cpp') diff --git a/src/common/cpu_features.cpp b/src/common/cpu_features.cpp index 52fd003c44..93eecb1dc5 100644 --- a/src/common/cpu_features.cpp +++ b/src/common/cpu_features.cpp @@ -278,8 +278,16 @@ std::chrono::milliseconds WallClock::GetTimeMS() const { s64 WallClock::GetCNTPCT() const { if (!invariant) - return GetUptime() * NsToCNTPCTRatio::num / NsToCNTPCTRatio::den; - return MultiplyHigh(GetUptime(), cntpct_rdtsc_factor); + return MultiplyAndDivide64(GetUptime(), GetGuestCNTFRQ(), NsRatio::den); + return MultiplyHigh(GetUptime(), cntpct_rdtsc_factor.load(std::memory_order_relaxed)); +} + +void WallClock::SetGuestCNTFRQ(u64 frequency) { + guest_cntfrq.store(frequency, std::memory_order_relaxed); + if (invariant) { + cntpct_rdtsc_factor.store(GetFixedPoint64Factor(frequency, rdtsc_frequency), + std::memory_order_relaxed); + } } s64 WallClock::GetGPUTick() const { @@ -336,7 +344,7 @@ namespace { } // namespace WallClock::WallClock(bool invariant_, u64 rdtsc_frequency_) noexcept { - const u64 host_cntfrq = std::max(GetHostCNTFRQ(), 1); + host_cntfrq = std::max(GetHostCNTFRQ(), 1); ns_cntfrq_factor = GetFixedPointFactor(NsRatio::den, host_cntfrq); us_cntfrq_factor = GetFixedPointFactor(UsRatio::den, host_cntfrq); ms_cntfrq_factor = GetFixedPointFactor(MsRatio::den, host_cntfrq); @@ -361,6 +369,11 @@ s64 WallClock::GetCNTPCT() const { return MultiplyHigh(GetUptime(), guest_cntfrq_factor); } +void WallClock::SetGuestCNTFRQ(u64 frequency) { + guest_cntfrq.store(frequency, std::memory_order_relaxed); + guest_cntfrq_factor = GetFixedPointFactor(frequency, host_cntfrq); +} + s64 WallClock::GetGPUTick() const { return MultiplyHigh(GetUptime(), gputick_cntfrq_factor); } @@ -399,7 +412,11 @@ std::chrono::milliseconds WallClock::GetTimeMS() const { } s64 WallClock::GetCNTPCT() const { - return GetUptime() * NsToCNTPCTRatio::num / NsToCNTPCTRatio::den; + return MultiplyAndDivide64(GetUptime(), GetGuestCNTFRQ(), NsRatio::den); +} + +void WallClock::SetGuestCNTFRQ(u64 frequency) { + guest_cntfrq.store(frequency, std::memory_order_relaxed); } s64 WallClock::GetGPUTick() const { @@ -419,9 +436,13 @@ u64 WallClock::NsToTicks(std::chrono::nanoseconds ns) const { } #endif +u64 WallClock::CPUTickToGuestCNTPCT(u64 cpu_tick) const { + return MultiplyAndDivide64(cpu_tick, GetGuestCNTFRQ(), CPUTickFreq); +} + // Wall clock MUST be initialized AFTER g_cpu_caps // C++ only guarantees ctor init in the order they appear in TU -const WallClock g_wall_clock = [] { +WallClock g_wall_clock = [] { #if defined(ARCHITECTURE_x86_64) auto const& caps = Common::g_cpu_caps; return WallClock(caps.invariant_tsc && caps.tsc_frequency > std::nano::den, caps.tsc_frequency); -- cgit v1.2.3