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runtime: do not call timeBeginPeriod on windows 

Calling timeBeginPeriod changes Windows global timer resolution
from 15ms to 1ms. This used to improve Go runtime scheduler
performance, but not anymore. Thanks to @aclements, scheduler now
behaves the same way if we call timeBeginPeriod or not.

Remove call to timeBeginPeriod, since it is machine global
resource, and there are downsides of using low timer resolution.
See issue #8687 for details.

Fixes #8687

Change-Id: Ib7e41aa4a81861b62a900e0e62776c9ef19bfb73
Reviewed-on: https://go-review.googlesource.com/17164
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
This commit is contained in:
Alex Brainman 2015-11-23 15:26:00 +11:00
parent b5fe07710f
commit ab4c9298b8
3 changed files with 2 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
src/runtime/export_windows_test.go
View File

@ -8,10 +8,7 @@ package runtime
import "unsafe" import "unsafe"
var ( var TestingWER = &testingWER
TestingWER = &testingWER
TimeBeginPeriodRetValue = &timeBeginPeriodRetValue
)
func NumberOfProcessors() int32 { func NumberOfProcessors() int32 {
var info systeminfo var info systeminfo

8
src/runtime/os1_windows.go
View File

@ -47,7 +47,6 @@ import (
//go:cgo_import_dynamic runtime._WaitForSingleObject WaitForSingleObject%2 "kernel32.dll" //go:cgo_import_dynamic runtime._WaitForSingleObject WaitForSingleObject%2 "kernel32.dll"
//go:cgo_import_dynamic runtime._WriteConsoleW WriteConsoleW%5 "kernel32.dll" //go:cgo_import_dynamic runtime._WriteConsoleW WriteConsoleW%5 "kernel32.dll"
//go:cgo_import_dynamic runtime._WriteFile WriteFile%5 "kernel32.dll" //go:cgo_import_dynamic runtime._WriteFile WriteFile%5 "kernel32.dll"
//go:cgo_import_dynamic runtime._timeBeginPeriod timeBeginPeriod%1 "winmm.dll"
var ( var (
// Following syscalls are available on every Windows PC. // Following syscalls are available on every Windows PC.
@ -90,8 +89,7 @@ var (
_WSAGetOverlappedResult, _WSAGetOverlappedResult,
_WaitForSingleObject, _WaitForSingleObject,
_WriteConsoleW, _WriteConsoleW,
_WriteFile, _WriteFile stdFunction
_timeBeginPeriod stdFunction
// Following syscalls are only available on some Windows PCs. // Following syscalls are only available on some Windows PCs.
// We will load syscalls, if available, before using them. // We will load syscalls, if available, before using them.
@ -161,8 +159,6 @@ const (
// in sys_windows_386.s and sys_windows_amd64.s // in sys_windows_386.s and sys_windows_amd64.s
func externalthreadhandler() func externalthreadhandler()
var timeBeginPeriodRetValue uint32
func osinit() { func osinit() {
asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall)) asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall))
@ -178,8 +174,6 @@ func osinit() {
stdcall2(_SetConsoleCtrlHandler, funcPC(ctrlhandler), 1) stdcall2(_SetConsoleCtrlHandler, funcPC(ctrlhandler), 1)
timeBeginPeriodRetValue = uint32(stdcall1(_timeBeginPeriod, 1))
ncpu = getproccount() ncpu = getproccount()
// Windows dynamic priority boosting assumes that a process has different types // Windows dynamic priority boosting assumes that a process has different types

7
src/runtime/syscall_windows_test.go
View File

@ -642,13 +642,6 @@ uintptr_t cfunc(callback f, uintptr_t n) {
} }
} }
func TestTimeBeginPeriod(t *testing.T) {
const TIMERR_NOERROR = 0
if *runtime.TimeBeginPeriodRetValue != TIMERR_NOERROR {
t.Fatalf("timeBeginPeriod failed: it returned %d", *runtime.TimeBeginPeriodRetValue)
}
}
// removeOneCPU removes one (any) cpu from affinity mask. // removeOneCPU removes one (any) cpu from affinity mask.
// It returns new affinity mask. // It returns new affinity mask.
func removeOneCPU(mask uintptr) (uintptr, error) { func removeOneCPU(mask uintptr) (uintptr, error) {