1 /* 2 * Copyright 2011-2015 Samy Al Bahra. 3 * Copyright 2011 David Joseph. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <ck_barrier.h> 29 #include <ck_pr.h> 30 31 void 32 ck_barrier_centralized(struct ck_barrier_centralized *barrier, 33 struct ck_barrier_centralized_state *state, 34 unsigned int n_threads) 35 { 36 unsigned int sense, value; 37 38 /* 39 * Every execution context has a sense associated with it. 40 * This sense is reversed when the barrier is entered. Every 41 * thread will spin on the global sense until the last thread 42 * reverses it. 43 */ 44 sense = state->sense = ~state->sense; 45 value = ck_pr_faa_uint(&barrier->value, 1); 46 if (value == n_threads - 1) { 47 ck_pr_store_uint(&barrier->value, 0); 48 ck_pr_fence_memory(); 49 ck_pr_store_uint(&barrier->sense, sense); 50 return; 51 } 52 53 ck_pr_fence_atomic_load(); 54 while (sense != ck_pr_load_uint(&barrier->sense)) 55 ck_pr_stall(); 56 57 ck_pr_fence_acquire(); 58 return; 59 } 60