From ef97bba4eec391707d08870252e555f3797ce270 Mon Sep 17 00:00:00 2001 From: Alex Brainman Date: Sun, 19 Jul 2020 16:06:48 +1000 Subject: [PATCH 6/9] runtime: use CreateWaitableTimerEx to implement usleep MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit @jstarks suggested that recent versions of Windows provide access to high resolution timers. See https://github.com/golang/go/issues/8687#issuecomment-656259353 for details. I tried to run this C program on my Windows 10 computer ``` #include #include #pragma comment(lib, "Winmm.lib") // Apparently this is already defined when I use msvc cl. //#define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION = 0x00000002; int usleep(HANDLE timer, LONGLONG d) { LARGE_INTEGER liDueTime; DWORD ret; LARGE_INTEGER StartingTime, EndingTime, ElapsedMicroseconds; LARGE_INTEGER Frequency; QueryPerformanceFrequency(&Frequency); QueryPerformanceCounter(&StartingTime); liDueTime.QuadPart = d; liDueTime.QuadPart = liDueTime.QuadPart * 10; // us into 100 of ns units liDueTime.QuadPart = -liDueTime.QuadPart; // negative for relative dure time if (!SetWaitableTimer(timer, &liDueTime, 0, NULL, NULL, 0)) { printf("SetWaitableTimer failed: errno=%d\n", GetLastError()); return 1; } ret = WaitForSingleObject(timer, INFINITE); if (ret != WAIT_OBJECT_0) { printf("WaitForSingleObject failed: ret=%d errno=%d\n", ret, GetLastError()); return 1; } QueryPerformanceCounter(&EndingTime); ElapsedMicroseconds.QuadPart = EndingTime.QuadPart - StartingTime.QuadPart; ElapsedMicroseconds.QuadPart *= 1000000; ElapsedMicroseconds.QuadPart /= Frequency.QuadPart; printf("delay is %lld us - slept for %lld us\n", d, ElapsedMicroseconds.QuadPart); return 0; } int testTimer(DWORD createFlag) { HANDLE timer; timer = CreateWaitableTimerEx(NULL, NULL, createFlag, TIMER_ALL_ACCESS); if (timer == NULL) { printf("CreateWaitableTimerEx failed: errno=%d\n", GetLastError()); return 1; } usleep(timer, 1000LL); usleep(timer, 100LL); usleep(timer, 10LL); usleep(timer, 1LL); CloseHandle(timer); return 0; } int main() { printf("\n1. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is off - timeBeginPeriod is off\n"); testTimer(0); printf("\n2. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is on - timeBeginPeriod is off\n"); testTimer(CREATE_WAITABLE_TIMER_HIGH_RESOLUTION); timeBeginPeriod(1); printf("\n3. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is off - timeBeginPeriod is on\n"); testTimer(0); printf("\n4. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is on - timeBeginPeriod is on\n"); testTimer(CREATE_WAITABLE_TIMER_HIGH_RESOLUTION); } ``` and I see this output ``` 1. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is off - timeBeginPeriod is off delay is 1000 us - slept for 4045 us delay is 100 us - slept for 3915 us delay is 10 us - slept for 3291 us delay is 1 us - slept for 2234 us 2. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is on - timeBeginPeriod is off delay is 1000 us - slept for 1076 us delay is 100 us - slept for 569 us delay is 10 us - slept for 585 us delay is 1 us - slept for 17 us 3. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is off - timeBeginPeriod is on delay is 1000 us - slept for 742 us delay is 100 us - slept for 893 us delay is 10 us - slept for 414 us delay is 1 us - slept for 920 us 4. CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is on - timeBeginPeriod is on delay is 1000 us - slept for 1466 us delay is 100 us - slept for 559 us delay is 10 us - slept for 535 us delay is 1 us - slept for 5 us ``` That shows, that indeed using CREATE_WAITABLE_TIMER_HIGH_RESOLUTION will provide sleeps as low as about 500 microseconds, while our current approach provides about 1 millisecond sleep. New approach also does not require for timeBeginPeriod to be on, so this change solves long standing problem with go programs draining laptop battery, because it calls timeBeginPeriod. This change will only run on systems where CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag is available. If not available, the runtime will fallback to original code that uses timeBeginPeriod. This is how this change affects benchmark reported in issue #14790 name               old time/op  new time/op  delta ChanToSyscallPing  1.05ms ± 2%  0.68ms ±11%  -35.43%  (p=0.000 n=10+10) The benchmark was run with GOMAXPROCS set to 1. Fixes #8687 Updates #14790 Change-Id: I5b97ba58289c088c17c05292e12e45285c467eae --- src/runtime/os_windows.go | 58 +++++++++++++++++++++++++++++++++ src/runtime/sys_windows_386.s | 36 ++++++++++++++++++++ src/runtime/sys_windows_amd64.s | 32 ++++++++++++++++++ src/runtime/sys_windows_arm.s | 18 ++++++++++ 4 files changed, 144 insertions(+) diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go index 769197db46..9aadd993f2 100644 --- a/src/runtime/os_windows.go +++ b/src/runtime/os_windows.go @@ -21,6 +21,7 @@ const ( //go:cgo_import_dynamic runtime._CreateIoCompletionPort CreateIoCompletionPort%4 "kernel32.dll" //go:cgo_import_dynamic runtime._CreateThread CreateThread%6 "kernel32.dll" //go:cgo_import_dynamic runtime._CreateWaitableTimerA CreateWaitableTimerA%3 "kernel32.dll" +//go:cgo_import_dynamic runtime._CreateWaitableTimerExW CreateWaitableTimerExW%4 "kernel32.dll" //go:cgo_import_dynamic runtime._DuplicateHandle DuplicateHandle%7 "kernel32.dll" //go:cgo_import_dynamic runtime._ExitProcess ExitProcess%1 "kernel32.dll" //go:cgo_import_dynamic runtime._FreeEnvironmentStringsW FreeEnvironmentStringsW%1 "kernel32.dll" @@ -71,6 +72,7 @@ var ( _CreateIoCompletionPort, _CreateThread, _CreateWaitableTimerA, + _CreateWaitableTimerExW, _DuplicateHandle, _ExitProcess, _FreeEnvironmentStringsW, @@ -158,6 +160,8 @@ type mOS struct { waitsema uintptr // semaphore for parking on locks resumesema uintptr // semaphore to indicate suspend/resume + highResTimer uintptr // high resolution timer handle used in usleep + // preemptExtLock synchronizes preemptM with entry/exit from // external C code. // @@ -415,6 +419,12 @@ const osRelaxMinNS = 60 * 1e6 // if we're already using the CPU, but if all Ps are idle there's no // need to consume extra power to drive the high-res timer. func osRelax(relax bool) uint32 { + if haveHighResTimer { + // Only call timeBeginPeriod/timeEndPeriod, if + // high resolution timer is not available. + return 0 + } + if relax { return uint32(stdcall1(_timeEndPeriod, 1)) } else { @@ -422,6 +432,37 @@ func osRelax(relax bool) uint32 { } } +// haveHighResTimer determines, if CreateWaitableTimerEx +// CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag is available. +var haveHighResTimer = false + +// createHighResTimer calls CreateWaitableTimerEx with +// CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag to create high +// resolution timer. createHighResTimer returns new timer +// handle or 0, if CreateWaitableTimerEx failed. +func createHighResTimer() uintptr { + const ( + // As per @jstarks, see + // https://github.com/golang/go/issues/8687#issuecomment-656259353 + _CREATE_WAITABLE_TIMER_HIGH_RESOLUTION = 0x00000002 + _TIMER_ALL_ACCESS = 0x1F0003 + ) + return stdcall4(_CreateWaitableTimerExW, 0, 0, _CREATE_WAITABLE_TIMER_HIGH_RESOLUTION, _TIMER_ALL_ACCESS) +} + +func initHighResTimer() { + if GOARCH == "arm" { + // TODO: Not yet implemented. + return + } + h := createHighResTimer() + if h != 0 { + haveHighResTimer = true + usleep2Addr = unsafe.Pointer(funcPC(usleep2HighRes)) + stdcall1(_CloseHandle, h) + } +} + func osinit() { asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall)) usleep2Addr = unsafe.Pointer(funcPC(usleep2)) @@ -437,6 +478,7 @@ func osinit() { stdcall2(_SetConsoleCtrlHandler, funcPC(ctrlhandler), 1) + initHighResTimer() timeBeginPeriodRetValue = osRelax(false) ncpu = getproccount() @@ -852,9 +894,20 @@ func minit() { var thandle uintptr stdcall7(_DuplicateHandle, currentProcess, currentThread, currentProcess, uintptr(unsafe.Pointer(&thandle)), 0, 0, _DUPLICATE_SAME_ACCESS) + // Configure usleep timer, if possible. + var timer uintptr + if haveHighResTimer { + timer = createHighResTimer() + if timer == 0 { + print("runtime: CreateWaitableTimerEx failed; errno=", getlasterror(), "\n") + throw("CreateWaitableTimerEx when creating timer failed") + } + } + mp := getg().m lock(&mp.threadLock) mp.thread = thandle + mp.highResTimer = timer unlock(&mp.threadLock) // Query the true stack base from the OS. Currently we're @@ -892,6 +945,10 @@ func unminit() { lock(&mp.threadLock) stdcall1(_CloseHandle, mp.thread) mp.thread = 0 + if mp.highResTimer != 0 { + stdcall1(_CloseHandle, mp.highResTimer) + mp.highResTimer = 0 + } unlock(&mp.threadLock) } @@ -987,6 +1044,7 @@ func stdcall7(fn stdFunction, a0, a1, a2, a3, a4, a5, a6 uintptr) uintptr { // in sys_windows_386.s and sys_windows_amd64.s func onosstack(fn unsafe.Pointer, arg uint32) func usleep2(usec uint32) +func usleep2HighRes(usec uint32) func switchtothread() var usleep2Addr unsafe.Pointer diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s index 9e1f40925d..4ac1527ab1 100644 --- a/src/runtime/sys_windows_386.s +++ b/src/runtime/sys_windows_386.s @@ -428,6 +428,42 @@ TEXT runtime·usleep2(SB),NOSPLIT,$20 MOVL BP, SP RET +// Runs on OS stack. duration (in 100ns units) is in BX. +TEXT runtime·usleep2HighRes(SB),NOSPLIT,$36 + // Want negative 100ns units. + NEGL BX + MOVL $-1, hi-4(SP) + MOVL BX, lo-8(SP) + + get_tls(CX) + MOVL g(CX), CX + MOVL g_m(CX), CX + MOVL (m_mOS+mOS_highResTimer)(CX), CX + MOVL CX, saved_timer-12(SP) + + MOVL $0, fResume-16(SP) + MOVL $0, lpArgToCompletionRoutine-20(SP) + MOVL $0, pfnCompletionRoutine-24(SP) + MOVL $0, lPeriod-28(SP) + LEAL lo-8(SP), BX + MOVL BX, lpDueTime-32(SP) + MOVL CX, hTimer-36(SP) + MOVL SP, BP + MOVL runtime·_SetWaitableTimer(SB), AX + CALL AX + MOVL BP, SP + + MOVL $0, ptime-28(SP) + MOVL $0, alertable-32(SP) + MOVL saved_timer-12(SP), CX + MOVL CX, handle-36(SP) + MOVL SP, BP + MOVL runtime·_NtWaitForSingleObject(SB), AX + CALL AX + MOVL BP, SP + + RET + // Runs on OS stack. TEXT runtime·switchtothread(SB),NOSPLIT,$0 MOVL SP, BP diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s index 6c8eecd4e7..847542592b 100644 --- a/src/runtime/sys_windows_amd64.s +++ b/src/runtime/sys_windows_amd64.s @@ -457,6 +457,38 @@ TEXT runtime·usleep2(SB),NOSPLIT|NOFRAME,$48 MOVQ 40(SP), SP RET +// Runs on OS stack. duration (in 100ns units) is in BX. +TEXT runtime·usleep2HighRes(SB),NOSPLIT|NOFRAME,$72 + MOVQ SP, AX + ANDQ $~15, SP // alignment as per Windows requirement + MOVQ AX, 64(SP) + + get_tls(CX) + MOVQ g(CX), CX + MOVQ g_m(CX), CX + MOVQ (m_mOS+mOS_highResTimer)(CX), CX // hTimer + MOVQ CX, 48(SP) // save hTimer for later + // Want negative 100ns units. + NEGQ BX + LEAQ 56(SP), DX // lpDueTime + MOVQ BX, (DX) + MOVQ $0, R8 // lPeriod + MOVQ $0, R9 // pfnCompletionRoutine + MOVQ $0, AX + MOVQ AX, 32(SP) // lpArgToCompletionRoutine + MOVQ AX, 40(SP) // fResume + MOVQ runtime·_SetWaitableTimer(SB), AX + CALL AX + + MOVQ 48(SP), CX // handle + MOVQ $0, DX // alertable + MOVQ $0, R8 // ptime + MOVQ runtime·_NtWaitForSingleObject(SB), AX + CALL AX + + MOVQ 64(SP), SP + RET + // Runs on OS stack. TEXT runtime·switchtothread(SB),NOSPLIT|NOFRAME,$0 MOVQ SP, AX diff --git a/src/runtime/sys_windows_arm.s b/src/runtime/sys_windows_arm.s index 256b5ff7f0..e6c61a4e42 100644 --- a/src/runtime/sys_windows_arm.s +++ b/src/runtime/sys_windows_arm.s @@ -468,6 +468,24 @@ TEXT runtime·usleep2(SB),NOSPLIT|NOFRAME,$0 MOVW R4, R13 // Restore SP MOVM.IA.W (R13), [R4, R15] // pop {R4, pc} +// Runs on OS stack. Duration (in 100ns units) is in R0. +// TODO: neeeds to be implemented properly. +TEXT runtime·usleep2HighRes(SB),NOSPLIT|NOFRAME,$0 + MOVM.DB.W [R4, R14], (R13) // push {r4, lr} + MOVW R13, R4 // Save SP + SUB $8, R13 // R13 = R13 - 8 + BIC $0x7, R13 // Align SP for ABI + RSB $0, R0, R3 // R3 = -R0 + MOVW $0, R1 // R1 = FALSE (alertable) + MOVW $-1, R0 // R0 = handle + MOVW R13, R2 // R2 = pTime + MOVW R3, 0(R2) // time_lo + MOVW R0, 4(R2) // time_hi + MOVW runtime·_NtWaitForSingleObject(SB), R3 + BL (R3) + MOVW R4, R13 // Restore SP + MOVM.IA.W (R13), [R4, R15] // pop {R4, pc} + // Runs on OS stack. TEXT runtime·switchtothread(SB),NOSPLIT|NOFRAME,$0 MOVM.DB.W [R4, R14], (R13) // push {R4, lr} -- 2.29.1