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comparison libgomp/parallel.c @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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-1:000000000000 0:a06113de4d67
1 /* Copyright (C) 2005, 2007, 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 file handles the (bare) PARALLEL construct. */
26
27 #include "libgomp.h"
28 #include <limits.h>
29
30
31 /* Determine the number of threads to be launched for a PARALLEL construct.
32 This algorithm is explicitly described in OpenMP 3.0 section 2.4.1.
33 SPECIFIED is a combination of the NUM_THREADS clause and the IF clause.
34 If the IF clause is false, SPECIFIED is forced to 1. When NUM_THREADS
35 is not present, SPECIFIED is 0. */
36
37 unsigned
38 gomp_resolve_num_threads (unsigned specified, unsigned count)
39 {
40 struct gomp_thread *thread = gomp_thread();
41 struct gomp_task_icv *icv;
42 unsigned threads_requested, max_num_threads, num_threads;
43 unsigned long remaining;
44
45 icv = gomp_icv (false);
46
47 if (specified == 1)
48 return 1;
49 else if (thread->ts.active_level >= 1 && !icv->nest_var)
50 return 1;
51 else if (thread->ts.active_level >= gomp_max_active_levels_var)
52 return 1;
53
54 /* If NUM_THREADS not specified, use nthreads_var. */
55 if (specified == 0)
56 threads_requested = icv->nthreads_var;
57 else
58 threads_requested = specified;
59
60 max_num_threads = threads_requested;
61
62 /* If dynamic threads are enabled, bound the number of threads
63 that we launch. */
64 if (icv->dyn_var)
65 {
66 unsigned dyn = gomp_dynamic_max_threads ();
67 if (dyn < max_num_threads)
68 max_num_threads = dyn;
69
70 /* Optimization for parallel sections. */
71 if (count && count < max_num_threads)
72 max_num_threads = count;
73 }
74
75 /* ULONG_MAX stands for infinity. */
76 if (__builtin_expect (gomp_thread_limit_var == ULONG_MAX, 1)
77 || max_num_threads == 1)
78 return max_num_threads;
79
80 #ifdef HAVE_SYNC_BUILTINS
81 do
82 {
83 remaining = gomp_remaining_threads_count;
84 num_threads = max_num_threads;
85 if (num_threads > remaining)
86 num_threads = remaining + 1;
87 }
88 while (__sync_val_compare_and_swap (&gomp_remaining_threads_count,
89 remaining, remaining - num_threads + 1)
90 != remaining);
91 #else
92 gomp_mutex_lock (&gomp_remaining_threads_lock);
93 num_threads = max_num_threads;
94 remaining = gomp_remaining_threads_count;
95 if (num_threads > remaining)
96 num_threads = remaining + 1;
97 gomp_remaining_threads_count -= num_threads - 1;
98 gomp_mutex_unlock (&gomp_remaining_threads_lock);
99 #endif
100
101 return num_threads;
102 }
103
104 void
105 GOMP_parallel_start (void (*fn) (void *), void *data, unsigned num_threads)
106 {
107 num_threads = gomp_resolve_num_threads (num_threads, 0);
108 gomp_team_start (fn, data, num_threads, gomp_new_team (num_threads));
109 }
110
111 void
112 GOMP_parallel_end (void)
113 {
114 if (__builtin_expect (gomp_thread_limit_var != ULONG_MAX, 0))
115 {
116 struct gomp_thread *thr = gomp_thread ();
117 struct gomp_team *team = thr->ts.team;
118 if (team && team->nthreads > 1)
119 {
120 #ifdef HAVE_SYNC_BUILTINS
121 __sync_fetch_and_add (&gomp_remaining_threads_count,
122 1UL - team->nthreads);
123 #else
124 gomp_mutex_lock (&gomp_remaining_threads_lock);
125 gomp_remaining_threads_count -= team->nthreads - 1;
126 #endif
127 }
128 }
129 gomp_team_end ();
130 }
131
132
133 /* The public OpenMP API for thread and team related inquiries. */
134
135 int
136 omp_get_num_threads (void)
137 {
138 struct gomp_team *team = gomp_thread ()->ts.team;
139 return team ? team->nthreads : 1;
140 }
141
142 int
143 omp_get_thread_num (void)
144 {
145 return gomp_thread ()->ts.team_id;
146 }
147
148 /* This wasn't right for OpenMP 2.5. Active region used to be non-zero
149 when the IF clause doesn't evaluate to false, starting with OpenMP 3.0
150 it is non-zero with more than one thread in the team. */
151
152 int
153 omp_in_parallel (void)
154 {
155 return gomp_thread ()->ts.active_level > 0;
156 }
157
158 int
159 omp_get_level (void)
160 {
161 return gomp_thread ()->ts.level;
162 }
163
164 int
165 omp_get_ancestor_thread_num (int level)
166 {
167 struct gomp_team_state *ts = &gomp_thread ()->ts;
168 if (level < 0 || level > ts->level)
169 return -1;
170 for (level = ts->level - level; level > 0; --level)
171 ts = &ts->team->prev_ts;
172 return ts->team_id;
173 }
174
175 int
176 omp_get_team_size (int level)
177 {
178 struct gomp_team_state *ts = &gomp_thread ()->ts;
179 if (level < 0 || level > ts->level)
180 return -1;
181 for (level = ts->level - level; level > 0; --level)
182 ts = &ts->team->prev_ts;
183 if (ts->team == NULL)
184 return 1;
185 else
186 return ts->team->nthreads;
187 }
188
189 int
190 omp_get_active_level (void)
191 {
192 return gomp_thread ()->ts.active_level;
193 }
194
195 ialias (omp_get_num_threads)
196 ialias (omp_get_thread_num)
197 ialias (omp_in_parallel)
198 ialias (omp_get_level)
199 ialias (omp_get_ancestor_thread_num)
200 ialias (omp_get_team_size)
201 ialias (omp_get_active_level)