bar.c revision 169695
1251886Speter/* Copyright (C) 2005 Free Software Foundation, Inc. 2251886Speter Contributed by Richard Henderson <rth@redhat.com>. 3264400Simp 4251886Speter This file is part of the GNU OpenMP Library (libgomp). 5251886Speter 6251886Speter Libgomp is free software; you can redistribute it and/or modify it 7251886Speter under the terms of the GNU Lesser General Public License as published by 8251886Speter the Free Software Foundation; either version 2.1 of the License, or 9251886Speter (at your option) any later version. 10251886Speter 11251886Speter Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 12251886Speter WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13251886Speter FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for 14251886Speter more details. 15251886Speter 16251886Speter You should have received a copy of the GNU Lesser General Public License 17251886Speter along with libgomp; see the file COPYING.LIB. If not, write to the 18251886Speter Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 19251886Speter MA 02110-1301, USA. */ 20251886Speter 21251886Speter/* As a special exception, if you link this library with other files, some 22251886Speter of which are compiled with GCC, to produce an executable, this library 23251886Speter does not by itself cause the resulting executable to be covered by the 24289180Speter GNU General Public License. This exception does not however invalidate 25251886Speter any other reasons why the executable file might be covered by the GNU 26251886Speter General Public License. */ 27251886Speter 28251886Speter/* This is a Linux specific implementation of a barrier synchronization 29275079Sbapt mechanism for libgomp. This type is private to the library. This 30275079Sbapt implementation uses atomic instructions and the futex syscall. */ 31251886Speter 32251886Speter#include "libgomp.h" 33251886Speter#include "futex.h" 34275079Sbapt#include <limits.h> 35251886Speter 36251886Speter 37void 38gomp_barrier_wait_end (gomp_barrier_t *bar, bool last) 39{ 40 if (last) 41 { 42 bar->generation++; 43 futex_wake (&bar->generation, INT_MAX); 44 } 45 else 46 { 47 unsigned int generation = bar->generation; 48 49 gomp_mutex_unlock (&bar->mutex); 50 51 do 52 futex_wait (&bar->generation, generation); 53 while (bar->generation == generation); 54 } 55 56 if (__sync_add_and_fetch (&bar->arrived, -1) == 0) 57 gomp_mutex_unlock (&bar->mutex); 58} 59 60void 61gomp_barrier_wait (gomp_barrier_t *barrier) 62{ 63 gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier)); 64} 65