|
0
|
1 /* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc.
|
|
|
2 Contributed by Richard Henderson <rth@redhat.com>.
|
|
|
3
|
|
|
4 This file is part of the GNU OpenMP Library (libgomp).
|
|
|
5
|
|
|
6 Libgomp is free software; you can redistribute it and/or modify it
|
|
|
7 under the terms of the GNU General Public License as published by
|
|
|
8 the Free Software Foundation; either version 3, or (at your option)
|
|
|
9 any later version.
|
|
|
10
|
|
|
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 General Public License for
|
|
|
14 more details.
|
|
|
15
|
|
|
16 Under Section 7 of GPL version 3, you are granted additional
|
|
|
17 permissions described in the GCC Runtime Library Exception, version
|
|
|
18 3.1, as published by the Free Software Foundation.
|
|
|
19
|
|
|
20 You should have received a copy of the GNU General Public License and
|
|
|
21 a copy of the GCC Runtime Library Exception along with this program;
|
|
|
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
|
23 <http://www.gnu.org/licenses/>. */
|
|
|
24
|
|
|
25 /* This is a Linux specific implementation of a barrier synchronization
|
|
|
26 mechanism for libgomp. This type is private to the library. This
|
|
|
27 implementation uses atomic instructions and the futex syscall. */
|
|
|
28
|
|
|
29 #include <limits.h>
|
|
|
30 #include "wait.h"
|
|
|
31
|
|
|
32
|
|
|
33 void
|
|
|
34 gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
|
|
|
35 {
|
|
|
36 if (__builtin_expect ((state & 1) != 0, 0))
|
|
|
37 {
|
|
|
38 /* Next time we'll be awaiting TOTAL threads again. */
|
|
|
39 bar->awaited = bar->total;
|
|
|
40 atomic_write_barrier ();
|
|
|
41 bar->generation += 4;
|
|
|
42 futex_wake ((int *) &bar->generation, INT_MAX);
|
|
|
43 }
|
|
|
44 else
|
|
|
45 {
|
|
|
46 unsigned int generation = state;
|
|
|
47
|
|
|
48 do
|
|
|
49 do_wait ((int *) &bar->generation, generation);
|
|
|
50 while (bar->generation == generation);
|
|
|
51 }
|
|
|
52 }
|
|
|
53
|
|
|
54 void
|
|
|
55 gomp_barrier_wait (gomp_barrier_t *bar)
|
|
|
56 {
|
|
|
57 gomp_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
|
|
|
58 }
|
|
|
59
|
|
|
60 /* Like gomp_barrier_wait, except that if the encountering thread
|
|
|
61 is not the last one to hit the barrier, it returns immediately.
|
|
|
62 The intended usage is that a thread which intends to gomp_barrier_destroy
|
|
|
63 this barrier calls gomp_barrier_wait, while all other threads
|
|
|
64 call gomp_barrier_wait_last. When gomp_barrier_wait returns,
|
|
|
65 the barrier can be safely destroyed. */
|
|
|
66
|
|
|
67 void
|
|
|
68 gomp_barrier_wait_last (gomp_barrier_t *bar)
|
|
|
69 {
|
|
|
70 gomp_barrier_state_t state = gomp_barrier_wait_start (bar);
|
|
|
71 if (state & 1)
|
|
|
72 gomp_barrier_wait_end (bar, state);
|
|
|
73 }
|
|
|
74
|
|
|
75 void
|
|
|
76 gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
|
|
|
77 {
|
|
|
78 futex_wake ((int *) &bar->generation, count == 0 ? INT_MAX : count);
|
|
|
79 }
|
|
|
80
|
|
|
81 void
|
|
|
82 gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
|
|
|
83 {
|
|
|
84 unsigned int generation;
|
|
|
85
|
|
|
86 if (__builtin_expect ((state & 1) != 0, 0))
|
|
|
87 {
|
|
|
88 /* Next time we'll be awaiting TOTAL threads again. */
|
|
|
89 struct gomp_thread *thr = gomp_thread ();
|
|
|
90 struct gomp_team *team = thr->ts.team;
|
|
|
91 bar->awaited = bar->total;
|
|
|
92 atomic_write_barrier ();
|
|
|
93 if (__builtin_expect (team->task_count, 0))
|
|
|
94 {
|
|
|
95 gomp_barrier_handle_tasks (state);
|
|
|
96 state &= ~1;
|
|
|
97 }
|
|
|
98 else
|
|
|
99 {
|
|
|
100 bar->generation = state + 3;
|
|
|
101 futex_wake ((int *) &bar->generation, INT_MAX);
|
|
|
102 return;
|
|
|
103 }
|
|
|
104 }
|
|
|
105
|
|
|
106 generation = state;
|
|
|
107 do
|
|
|
108 {
|
|
|
109 do_wait ((int *) &bar->generation, generation);
|
|
|
110 if (__builtin_expect (bar->generation & 1, 0))
|
|
|
111 gomp_barrier_handle_tasks (state);
|
|
|
112 if ((bar->generation & 2))
|
|
|
113 generation |= 2;
|
|
|
114 }
|
|
|
115 while (bar->generation != state + 4);
|
|
|
116 }
|
|
|
117
|
|
|
118 void
|
|
|
119 gomp_team_barrier_wait (gomp_barrier_t *bar)
|
|
|
120 {
|
|
|
121 gomp_team_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
|
|
|
122 }
|
