glibc/sysdeps/unix/sysv/linux/sched_getcpu.c
Florian Weimer 1d350aa060 Linux: Use rseq to accelerate sched_getcpu
Co-Authored-By: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2021-12-09 09:49:32 +01:00

50 lines
1.4 KiB
C

/* Copyright (C) 2007-2021 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/>. */
#include <errno.h>
#include <sched.h>
#include <sysdep.h>
#include <sysdep-vdso.h>
static int
vsyscall_sched_getcpu (void)
{
unsigned int cpu;
int r = -1;
#ifdef HAVE_GETCPU_VSYSCALL
r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
#else
r = INLINE_SYSCALL_CALL (getcpu, &cpu, NULL, NULL);
#endif
return r == -1 ? r : cpu;
}
#ifdef RSEQ_SIG
int
sched_getcpu (void)
{
int cpu_id = THREAD_GETMEM_VOLATILE (THREAD_SELF, rseq_area.cpu_id);
return __glibc_likely (cpu_id >= 0) ? cpu_id : vsyscall_sched_getcpu ();
}
#else /* RSEQ_SIG */
int
sched_getcpu (void)
{
return vsyscall_sched_getcpu ();
}
#endif /* RSEQ_SIG */