1 /* Copyright (C) 2008 Free Software Foundation, Inc.
2 Contributed by Jakub Jelinek <jakub@redhat.com>.
4 This file is part of the GNU OpenMP Library (libgomp).
6 Libgomp is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
16 You should have received a copy of the GNU Lesser General Public License
17 along with libgomp; see the file COPYING.LIB. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
19 MA 02110-1301, USA. */
21 /* As a special exception, if you link this library with other files, some
22 of which are compiled with GCC, to produce an executable, this library
23 does not by itself cause the resulting executable to be covered by the
24 GNU General Public License. This exception does not however invalidate
25 any other reasons why the executable file might be covered by the GNU
26 General Public License. */
28 /* This is a Linux specific implementation of a mutex synchronization
29 mechanism for libgomp. This type is private to the library. This
30 implementation uses atomic instructions and the futex syscall. */
40 #define FUTEX_PRIVATE_FLAG 128L
42 #ifdef HAVE_ATTRIBUTE_VISIBILITY
43 # pragma GCC visibility push(hidden)
46 extern long int gomp_futex_wait
, gomp_futex_wake
;
50 static inline void do_wait (int *addr
, int val
)
52 unsigned long long i
, count
= gomp_spin_count_var
;
54 if (__builtin_expect (gomp_managed_threads
> gomp_available_cpus
, 0))
55 count
= gomp_throttled_spin_count_var
;
56 for (i
= 0; i
< count
; i
++)
57 if (__builtin_expect (*addr
!= val
, 0))
61 futex_wait (addr
, val
);
64 #ifdef HAVE_ATTRIBUTE_VISIBILITY
65 # pragma GCC visibility pop
68 #endif /* GOMP_WAIT_H */