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| author | kib <kib@FreeBSD.org> | 2012-06-22 07:13:30 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2012-06-22 07:13:30 +0000 |
| commit | 13a9f42818f6b89a72b3e40923be809b490400d8 (patch) | |
| tree | 58a73d4c3dd528ab72afbea3d6243d4dd6c48c3e /lib/libc/gen/aux.c | |
| parent | 7b36a081088572ce45af9b675b5992adc971506d (diff) | |
| download | FreeBSD-src-13a9f42818f6b89a72b3e40923be809b490400d8.zip FreeBSD-src-13a9f42818f6b89a72b3e40923be809b490400d8.tar.gz | |
Use struct vdso_timehands data to implement fast gettimeofday(2) and
clock_gettime(2) functions if supported. The speedup seen in
microbenchmarks is in range 4x-7x depending on the hardware.
Only amd64 and i386 architectures are supported. Libc uses rdtsc and
kernel data to calculate current time, if enabled by kernel.
Hopefully, this code is going to migrate into vdso in some future.
Discussed with: bde
Reviewed by: jhb
Tested by: flo
MFC after: 1 month
Diffstat (limited to 'lib/libc/gen/aux.c')
| -rw-r--r-- | lib/libc/gen/aux.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/libc/gen/aux.c b/lib/libc/gen/aux.c index 4bf8643..3767ac0 100644 --- a/lib/libc/gen/aux.c +++ b/lib/libc/gen/aux.c @@ -66,6 +66,7 @@ __init_elf_aux_vector(void) static pthread_once_t aux_once = PTHREAD_ONCE_INIT; static int pagesize, osreldate, canary_len, ncpus, pagesizes_len; static char *canary, *pagesizes; +static void *timekeep; static void init_aux(void) @@ -101,6 +102,10 @@ init_aux(void) case AT_NCPUS: ncpus = aux->a_un.a_val; break; + + case AT_TIMEKEEP: + timekeep = aux->a_un.a_ptr; + break; } } } @@ -163,6 +168,16 @@ _elf_aux_info(int aux, void *buf, int buflen) } else res = EINVAL; break; + case AT_TIMEKEEP: + if (buflen == sizeof(void *)) { + if (timekeep != NULL) { + *(void **)buf = timekeep; + res = 0; + } else + res = ENOENT; + } else + res = EINVAL; + break; default: res = ENOENT; break; |
