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| author | Yuval Pavel Zholkover <paulzhol@gmail.com> | 2018-02-05 17:11:27 +0200 |
|---|---|---|
| committer | Ian Lance Taylor <iant@golang.org> | 2018-04-18 21:54:26 +0000 |
| commit | 744ccbb852f18241c637b2c6314b35fce7359916 (patch) | |
| tree | 7201dea7cc3ce21462c40af6a646f7ff0c0427db /src/runtime/os_freebsd.go | |
| parent | 236c567ba9b7767b6f1ebe32eb2d8f0018de8780 (diff) | |
| download | go-744ccbb852f18241c637b2c6314b35fce7359916.tar.gz go-744ccbb852f18241c637b2c6314b35fce7359916.zip | |
runtime: fast clock_gettime call on FreeBSD
Use AT_TIMEKEEP ELF aux entry to access a kernel mapped ring of timehands structs.
The timehands are updated by the kernel periodically, but for accurate measure the
timecounter still needs to be queried.
Currently the fast path is used only when kern.timecounter.hardware==TSC-low
or kern.timecounter.hardware=='ARM MPCore Timecounter',
other timecounters revert back to regular system call.
TODO: add support for HPET timecounter on 386/amd64.
Change-Id: I321ca4e92be63ba21a2574b758ef5c1e729086ad
Reviewed-on: https://go-review.googlesource.com/93156
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/runtime/os_freebsd.go')
| -rw-r--r-- | src/runtime/os_freebsd.go | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/runtime/os_freebsd.go b/src/runtime/os_freebsd.go index fafe7f470b..ef2a4652f4 100644 --- a/src/runtime/os_freebsd.go +++ b/src/runtime/os_freebsd.go @@ -378,9 +378,10 @@ func sysargs(argc int32, argv **byte) { } const ( - _AT_NULL = 0 // Terminates the vector - _AT_PAGESZ = 6 // Page size in bytes - _AT_HWCAP = 26 // CPU feature flags + _AT_NULL = 0 // Terminates the vector + _AT_PAGESZ = 6 // Page size in bytes + _AT_TIMEKEEP = 22 // Pointer to timehands. + _AT_HWCAP = 26 // CPU feature flags ) func sysauxv(auxv []uintptr) { @@ -390,6 +391,8 @@ func sysauxv(auxv []uintptr) { // _AT_NCPUS from auxv shouldn't be used due to golang.org/issue/15206 case _AT_PAGESZ: physPageSize = val + case _AT_TIMEKEEP: + timekeepSharedPage = (*vdsoTimekeep)(unsafe.Pointer(val)) } archauxv(tag, val) |