diff options
| author | Shenghou Ma <minux.ma@gmail.com> | 2012-11-09 14:19:07 +0800 |
|---|---|---|
| committer | Shenghou Ma <minux.ma@gmail.com> | 2012-11-09 14:19:07 +0800 |
| commit | 4022fc4e21d6c5feecb01248c25f8bc54e9762c2 (patch) | |
| tree | b37ffbe5bca8a8285b067ebf37886cf087470f4c /src/pkg/runtime | |
| parent | f668e0a5b3b1f393ecda995c92503da7b4c89e53 (diff) | |
| download | go-4022fc4e21d6c5feecb01248c25f8bc54e9762c2.tar.xz | |
runtime: use vDSO clock_gettime for time.now & runtime.nanotime on Linux/amd64
Performance improvement aside, time.Now() now gets real nanosecond resolution
on supported systems.
Benchmark done on Core i7-2600 @ 3.40GHz with kernel 3.5.2-gentoo.
original vDSO gettimeofday:
BenchmarkNow 100000000 27.4 ns/op
new vDSO gettimeofday fallback:
BenchmarkNow 100000000 27.6 ns/op
new vDSO clock_gettime:
BenchmarkNow 100000000 24.4 ns/op
R=golang-dev, bradfitz, iant, iant
CC=golang-dev
https://golang.org/cl/6814103
Diffstat (limited to 'src/pkg/runtime')
| -rw-r--r-- | src/pkg/runtime/sys_linux_amd64.s | 26 | ||||
| -rw-r--r-- | src/pkg/runtime/vdso_linux_amd64.c | 4 |
2 files changed, 19 insertions, 11 deletions
diff --git a/src/pkg/runtime/sys_linux_amd64.s b/src/pkg/runtime/sys_linux_amd64.s index ca78ffa6f6..cb6f4a8ca0 100644 --- a/src/pkg/runtime/sys_linux_amd64.s +++ b/src/pkg/runtime/sys_linux_amd64.s @@ -102,31 +102,37 @@ TEXT runtime·mincore(SB),7,$0-24 // func now() (sec int64, nsec int32) TEXT time·now(SB), 7, $32 + MOVQ runtime·__vdso_clock_gettime_sym(SB), AX + CMPQ AX, $0 + JEQ fallback_gtod + MOVL $0, DI // CLOCK_REALTIME + LEAQ 8(SP), SI + CALL AX + MOVQ 8(SP), AX // sec + MOVQ 16(SP), DX // nsec + MOVQ AX, sec+0(FP) + MOVL DX, nsec+8(FP) + RET +fallback_gtod: LEAQ 8(SP), DI MOVQ $0, SI MOVQ runtime·__vdso_gettimeofday_sym(SB), AX CALL AX MOVQ 8(SP), AX // sec MOVL 16(SP), DX // usec - - // sec is in AX, usec in DX - MOVQ AX, sec+0(FP) IMULQ $1000, DX + MOVQ AX, sec+0(FP) MOVL DX, nsec+8(FP) RET TEXT runtime·nanotime(SB), 7, $32 - LEAQ 8(SP), DI - MOVQ $0, SI - MOVQ $0xffffffffff600000, AX - CALL AX - MOVQ 8(SP), AX // sec - MOVL 16(SP), DX // usec + CALL time·now(SB) + MOVQ 0(SP), AX // sec + MOVL 8(SP), DX // nsec // sec is in AX, usec in DX // return nsec in AX IMULQ $1000000000, AX - IMULQ $1000, DX ADDQ DX, AX RET diff --git a/src/pkg/runtime/vdso_linux_amd64.c b/src/pkg/runtime/vdso_linux_amd64.c index 923bab0c2b..b125c8b051 100644 --- a/src/pkg/runtime/vdso_linux_amd64.c +++ b/src/pkg/runtime/vdso_linux_amd64.c @@ -161,11 +161,13 @@ static version_key linux26 = { (byte*)"LINUX_2.6", 0x3ae75f6 }; // initialize with vsyscall fallbacks void* runtime·__vdso_time_sym = (void*)0xffffffffff600400ULL; void* runtime·__vdso_gettimeofday_sym = (void*)0xffffffffff600000ULL; +void* runtime·__vdso_clock_gettime_sym = (void*)0; -#define SYM_KEYS_COUNT 2 +#define SYM_KEYS_COUNT 3 static symbol_key sym_keys[] = { { (byte*)"__vdso_time", &runtime·__vdso_time_sym }, { (byte*)"__vdso_gettimeofday", &runtime·__vdso_gettimeofday_sym }, + { (byte*)"__vdso_clock_gettime", &runtime·__vdso_clock_gettime_sym }, }; static void vdso_init_from_sysinfo_ehdr(struct vdso_info *vdso_info, Elf64_Ehdr* hdr) { |