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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2019-12-14 10:05:44 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-01-03 11:22:07 -0300 |
| commit | a9091a12444d551977adb6d8b45b2007881f1b8b (patch) | |
| tree | 6b4de13b241db8e6af35658f1b46fdd075696cd3 /math/test-fenv-return.c | |
| parent | ff500a623d1bf9fb24f30fa80451897b534549e1 (diff) | |
| download | glibc-a9091a12444d551977adb6d8b45b2007881f1b8b.tar.gz glibc-a9091a12444d551977adb6d8b45b2007881f1b8b.tar.xz glibc-a9091a12444d551977adb6d8b45b2007881f1b8b.zip | |
linux: Optimize fallback 32-bit clock_gettime
This patch avoid probing the __NR_clock_getttime64 syscall each time
__clock_gettime64 is issued on a kernel without 64 bit time support.
Once ENOSYS is obtained, only 32-bit clock_gettime are used.
The following snippet:
clock_gettime (CLOCK_REALTIME, &(struct timespec) { 0 });
clock_gettime (CLOCK_MONOTONIC, &(struct timespec) { 0 });
clock_gettime (CLOCK_BOOTTIME, &(struct timespec) { 0 });
clock_gettime (20, &(struct timespec) { 0 });
On a kernel without 64 bit time support and with vDSO support results
on the following syscalls:
syscall_0x193(0, 0xff87ba30, [...]) = -1 ENOSYS (Function not implemented)
clock_gettime(CLOCK_BOOTTIME, {tv_sec=927082, tv_nsec=474382032}) = 0
clock_gettime(0x14 /* CLOCK_??? */, 0xff87b9f8) = -1 EINVAL (Invalid argument)
While on a kernel without vDSO support:
syscall_0x193(0, 0xbec95550, 0xb6ed2000, 0x1, 0xbec95550, 0) = -1 (errno 38)
clock_gettime(CLOCK_REALTIME, {tv_sec=1576615930, tv_nsec=638250162}) = 0
clock_gettime(CLOCK_MONOTONIC, {tv_sec=1665478, tv_nsec=638779620}) = 0
clock_gettime(CLOCK_BOOTTIME, {tv_sec=1675418, tv_nsec=292932704}) = 0
clock_gettime(0x14 /* CLOCK_??? */, 0xbec95530) = -1 EINVAL (Invalid argument)
Checked on i686-linux-gnu on 4.15 kernel and on a 5.3 kernel.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Diffstat (limited to 'math/test-fenv-return.c')
0 files changed, 0 insertions, 0 deletions