diff --git a/src/common/x64/cpu_wait.cpp b/src/common/x64/cpu_wait.cpp new file mode 100644 index 0000000000..12f2e9d4b1 --- /dev/null +++ b/src/common/x64/cpu_wait.cpp @@ -0,0 +1,78 @@ +// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project +// SPDX-License-Identifier: GPL-3.0-or-later + +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#include + +#ifdef _MSC_VER +#include +#endif + +#include "common/x64/cpu_detect.h" +#include "common/x64/cpu_wait.h" +#include "common/x64/rdtsc.h" + +namespace Common::X64 { + +namespace { + +// 100,000 cycles is a reasonable amount of time to wait to save on CPU resources. +// For reference: +// At 1 GHz, 100K cycles is 100us +// At 2 GHz, 100K cycles is 50us +// At 4 GHz, 100K cycles is 25us +constexpr auto PauseCycles = 100'000U; + +} // Anonymous namespace + +#if defined(_MSC_VER) && !defined(__clang__) +__forceinline static void TPAUSE() { + static constexpr auto RequestC02State = 0U; + _tpause(RequestC02State, FencedRDTSC() + PauseCycles); +} + +__forceinline static void MWAITX() { + static constexpr auto EnableWaitTimeFlag = 1U << 1; + static constexpr auto RequestC1State = 0U; + + // monitor_var should be aligned to a cache line. + alignas(64) u64 monitor_var{}; + _mm_monitorx(&monitor_var, 0, 0); + _mm_mwaitx(EnableWaitTimeFlag, RequestC1State, PauseCycles); +} +#else +static void TPAUSE() { + static constexpr auto RequestC02State = 0U; + const auto tsc = FencedRDTSC() + PauseCycles; + const auto eax = static_cast(tsc & 0xFFFFFFFF); + const auto edx = static_cast(tsc >> 32); + asm volatile("tpause %0" : : "r"(RequestC02State), "d"(edx), "a"(eax)); +} + +static void MWAITX() { + static constexpr auto EnableWaitTimeFlag = 1U << 1; + static constexpr auto RequestC1State = 0U; + + // monitor_var should be aligned to a cache line. + alignas(64) u64 monitor_var{}; + asm volatile("monitorx" : : "a"(&monitor_var), "c"(0), "d"(0)); + asm volatile("mwaitx" : : "a"(RequestC1State), "b"(PauseCycles), "c"(EnableWaitTimeFlag)); +} +#endif + +void MicroSleep() { + static const bool has_waitpkg = GetCPUCaps().waitpkg; + static const bool has_monitorx = GetCPUCaps().monitorx; + + if (has_waitpkg) { + TPAUSE(); + } else if (has_monitorx) { + MWAITX(); + } else { + std::this_thread::yield(); + } +} + +} // namespace Common::X64 diff --git a/src/common/x64/cpu_wait.h b/src/common/x64/cpu_wait.h new file mode 100644 index 0000000000..99d3757a76 --- /dev/null +++ b/src/common/x64/cpu_wait.h @@ -0,0 +1,10 @@ +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#pragma once + +namespace Common::X64 { + +void MicroSleep(); + +} // namespace Common::X64