Merge pull request #9982 from Morph1984/tpause

x64: Make use of waitpkg instructions for power efficient sleeps
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liamwhite 2023-03-28 09:09:35 -04:00 committed by GitHub
commit 40efd2ab56
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8 changed files with 97 additions and 8 deletions

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@ -160,6 +160,8 @@ if(ARCHITECTURE_x86_64)
PRIVATE
x64/cpu_detect.cpp
x64/cpu_detect.h
x64/cpu_wait.cpp
x64/cpu_wait.h
x64/native_clock.cpp
x64/native_clock.h
x64/xbyak_abi.h

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@ -97,6 +97,7 @@ void AppendCPUInfo(FieldCollection& fc) {
add_field("CPU_Extension_x64_PCLMULQDQ", caps.pclmulqdq);
add_field("CPU_Extension_x64_POPCNT", caps.popcnt);
add_field("CPU_Extension_x64_SHA", caps.sha);
add_field("CPU_Extension_x64_WAITPKG", caps.waitpkg);
#else
fc.AddField(FieldType::UserSystem, "CPU_Model", "Other");
#endif

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@ -144,6 +144,7 @@ static CPUCaps Detect() {
caps.bmi2 = Common::Bit<8>(cpu_id[1]);
caps.sha = Common::Bit<29>(cpu_id[1]);
caps.waitpkg = Common::Bit<5>(cpu_id[2]);
caps.gfni = Common::Bit<8>(cpu_id[2]);
__cpuidex(cpu_id, 0x00000007, 0x00000001);

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@ -67,6 +67,7 @@ struct CPUCaps {
bool pclmulqdq : 1;
bool popcnt : 1;
bool sha : 1;
bool waitpkg : 1;
};
/**

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@ -0,0 +1,69 @@
// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <thread>
#ifdef _MSC_VER
#include <intrin.h>
#endif
#include "common/x64/cpu_detect.h"
#include "common/x64/cpu_wait.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:
// At 1 GHz, 100K cycles is 100us
// At 2 GHz, 100K cycles is 50us
// At 4 GHz, 100K cycles is 25us
static constexpr auto PauseCycles = 100'000;
_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:
// At 1 GHz, 100K cycles is 100us
// At 2 GHz, 100K cycles is 50us
// At 4 GHz, 100K cycles is 25us
static constexpr auto PauseCycles = 100'000;
const auto tsc = FencedRDTSC() + PauseCycles;
const auto eax = static_cast<u32>(tsc & 0xFFFFFFFF);
const auto edx = static_cast<u32>(tsc >> 32);
asm volatile("tpause %0" : : "r"(0), "d"(edx), "a"(eax));
}
#endif
void MicroSleep() {
static const bool has_waitpkg = GetCPUCaps().waitpkg;
if (has_waitpkg) {
TPAUSE();
} else {
std::this_thread::yield();
}
}
} // namespace Common::X64

10
src/common/x64/cpu_wait.h Normal file
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@ -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

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@ -27,16 +27,13 @@ __forceinline static u64 FencedRDTSC() {
}
#else
static u64 FencedRDTSC() {
u64 result;
u64 eax;
u64 edx;
asm volatile("lfence\n\t"
"rdtsc\n\t"
"shl $32, %%rdx\n\t"
"or %%rdx, %0\n\t"
"lfence"
: "=a"(result)
:
: "rdx", "memory", "cc");
return result;
"lfence\n\t"
: "=a"(eax), "=d"(edx));
return (edx << 32) | eax;
}
#endif

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@ -10,6 +10,10 @@
#include "common/windows/timer_resolution.h"
#endif
#ifdef ARCHITECTURE_x86_64
#include "common/x64/cpu_wait.h"
#endif
#include "common/microprofile.h"
#include "core/core_timing.h"
#include "core/core_timing_util.h"
@ -269,7 +273,11 @@ void CoreTiming::ThreadLoop() {
if (wait_time >= timer_resolution_ns) {
Common::Windows::SleepForOneTick();
} else {
#ifdef ARCHITECTURE_x86_64
Common::X64::MicroSleep();
#else
std::this_thread::yield();
#endif
}
}