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Use exclusively clock_gettime to implement gettimeofday.

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In 2.31 we changed most ports to implement gettimeofday using
clock_gettime(CLOCK_REALTIME[_COARSE]), but we kept around a handful
of Linux-specific implementations that went directly to the vDSO.

Actual performance testing (on x86-64) indicates that there is no
measurable difference between invoking the vDSO directly and calling
clock_gettime (which then calls into the vDSO), so remove all of these
for simplicity’s sake.
This commit is contained in:
Zack Weinberg 2019-08-28 08:30:28 -04:00
parent 9ac2398ef9
commit d5f4d0ac6a
No known key found for this signature in database
GPG Key ID: 5106A66578DC148C
4 changed files with 0 additions and 117 deletions
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20
sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
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/* Copyright (C) 2018-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#define USE_IFUNC_GETTIMEOFDAY
#include <sysdeps/unix/sysv/linux/gettimeofday.c>

58
sysdeps/unix/sysv/linux/gettimeofday.c
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/* gettimeofday - set time. Linux version.
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Optimize the function call by setting the PLT directly to vDSO symbol. */
#ifdef USE_IFUNC_GETTIMEOFDAY
# include <time.h>
# include <string.h>
# include <sysdep.h>
# include <sysdep-vdso.h>
# ifdef SHARED
# include <dl-vdso.h>
# include <libc-vdso.h>
static int
__gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
{
if (__glibc_unlikely (tz != 0))
memset (tz, 0, sizeof *tz);
return INLINE_SYSCALL_CALL (gettimeofday, tv, tz);
}
# undef INIT_ARCH
# define INIT_ARCH() \
void *vdso_gettimeofday = dl_vdso_vsym (HAVE_GETTIMEOFDAY_VSYSCALL)
libc_ifunc (__gettimeofday,
vdso_gettimeofday ? VDSO_IFUNC_RET (vdso_gettimeofday)
: (void *) __gettimeofday_syscall)
# else
int
__gettimeofday (struct timeval *restrict tv, void *restrict tz)
{
if (__glibc_unlikely (tz != 0))
memset (tz, 0, sizeof *tz);
return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
}
# endif
weak_alias (__gettimeofday, gettimeofday)
#else /* USE_IFUNC_GETTIMEOFDAY */
# include <time/gettimeofday.c>
#endif

19
sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
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/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#define USE_IFUNC_GETTIMEOFDAY
#include <sysdeps/unix/sysv/linux/gettimeofday.c>

20
sysdeps/unix/sysv/linux/x86/gettimeofday.c
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/* gettimeofday - get the time. Linux/x86 version.
Copyright (C) 2015-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#define USE_IFUNC_GETTIMEOFDAY
#include <sysdeps/unix/sysv/linux/gettimeofday.c>