1 /* Copyright (C) 2005-2017 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
4 This file is part of the GNU Offloading and Multi Processing Library
7 Libgomp is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
26 /* This file handles the (bare) PARALLEL construct. */
32 /* Determine the number of threads to be launched for a PARALLEL construct.
33 This algorithm is explicitly described in OpenMP 3.0 section 2.4.1.
34 SPECIFIED is a combination of the NUM_THREADS clause and the IF clause.
35 If the IF clause is false, SPECIFIED is forced to 1. When NUM_THREADS
36 is not present, SPECIFIED is 0. */
39 gomp_resolve_num_threads (unsigned specified
, unsigned count
)
41 struct gomp_thread
*thr
= gomp_thread ();
42 struct gomp_task_icv
*icv
;
43 unsigned threads_requested
, max_num_threads
, num_threads
;
45 struct gomp_thread_pool
*pool
;
47 icv
= gomp_icv (false);
51 else if (thr
->ts
.active_level
>= 1 && !icv
->nest_var
)
53 else if (thr
->ts
.active_level
>= gomp_max_active_levels_var
)
56 /* If NUM_THREADS not specified, use nthreads_var. */
58 threads_requested
= icv
->nthreads_var
;
60 threads_requested
= specified
;
62 max_num_threads
= threads_requested
;
64 /* If dynamic threads are enabled, bound the number of threads
68 unsigned dyn
= gomp_dynamic_max_threads ();
69 if (dyn
< max_num_threads
)
70 max_num_threads
= dyn
;
72 /* Optimization for parallel sections. */
73 if (count
&& count
< max_num_threads
)
74 max_num_threads
= count
;
77 /* UINT_MAX stands for infinity. */
78 if (__builtin_expect (icv
->thread_limit_var
== UINT_MAX
, 1)
79 || max_num_threads
== 1)
80 return max_num_threads
;
82 /* The threads_busy counter lives in thread_pool, if there
83 isn't a thread_pool yet, there must be just one thread
84 in the contention group. If thr->team is NULL, this isn't
85 nested parallel, so there is just one thread in the
86 contention group as well, no need to handle it atomically. */
87 pool
= thr
->thread_pool
;
88 if (thr
->ts
.team
== NULL
|| pool
== NULL
)
90 num_threads
= max_num_threads
;
91 if (num_threads
> icv
->thread_limit_var
)
92 num_threads
= icv
->thread_limit_var
;
94 pool
->threads_busy
= num_threads
;
98 #ifdef HAVE_SYNC_BUILTINS
101 busy
= pool
->threads_busy
;
102 num_threads
= max_num_threads
;
103 if (icv
->thread_limit_var
- busy
+ 1 < num_threads
)
104 num_threads
= icv
->thread_limit_var
- busy
+ 1;
106 while (__sync_val_compare_and_swap (&pool
->threads_busy
,
107 busy
, busy
+ num_threads
- 1)
110 gomp_mutex_lock (&gomp_managed_threads_lock
);
111 num_threads
= max_num_threads
;
112 busy
= pool
->threads_busy
;
113 if (icv
->thread_limit_var
- busy
+ 1 < num_threads
)
114 num_threads
= icv
->thread_limit_var
- busy
+ 1;
115 pool
->threads_busy
+= num_threads
- 1;
116 gomp_mutex_unlock (&gomp_managed_threads_lock
);
123 GOMP_parallel_start (void (*fn
) (void *), void *data
, unsigned num_threads
)
125 num_threads
= gomp_resolve_num_threads (num_threads
, 0);
126 gomp_team_start (fn
, data
, num_threads
, 0, gomp_new_team (num_threads
));
130 GOMP_parallel_end (void)
132 struct gomp_task_icv
*icv
= gomp_icv (false);
133 if (__builtin_expect (icv
->thread_limit_var
!= UINT_MAX
, 0))
135 struct gomp_thread
*thr
= gomp_thread ();
136 struct gomp_team
*team
= thr
->ts
.team
;
137 unsigned int nthreads
= team
? team
->nthreads
: 1;
141 /* If not nested, there is just one thread in the
142 contention group left, no need for atomicity. */
143 if (thr
->ts
.team
== NULL
)
144 thr
->thread_pool
->threads_busy
= 1;
147 #ifdef HAVE_SYNC_BUILTINS
148 __sync_fetch_and_add (&thr
->thread_pool
->threads_busy
,
151 gomp_mutex_lock (&gomp_managed_threads_lock
);
152 thr
->thread_pool
->threads_busy
-= nthreads
- 1;
153 gomp_mutex_unlock (&gomp_managed_threads_lock
);
161 ialias (GOMP_parallel_end
)
164 GOMP_parallel (void (*fn
) (void *), void *data
, unsigned num_threads
, unsigned int flags
)
166 num_threads
= gomp_resolve_num_threads (num_threads
, 0);
167 gomp_team_start (fn
, data
, num_threads
, flags
, gomp_new_team (num_threads
));
169 ialias_call (GOMP_parallel_end
) ();
173 GOMP_cancellation_point (int which
)
175 if (!gomp_cancel_var
)
178 struct gomp_thread
*thr
= gomp_thread ();
179 struct gomp_team
*team
= thr
->ts
.team
;
180 if (which
& (GOMP_CANCEL_LOOP
| GOMP_CANCEL_SECTIONS
))
184 return team
->work_share_cancelled
!= 0;
186 else if (which
& GOMP_CANCEL_TASKGROUP
)
188 if (thr
->task
->taskgroup
&& thr
->task
->taskgroup
->cancelled
)
190 /* FALLTHRU into the GOMP_CANCEL_PARALLEL case,
191 as #pragma omp cancel parallel also cancels all explicit
195 return gomp_team_barrier_cancelled (&team
->barrier
);
198 ialias (GOMP_cancellation_point
)
201 GOMP_cancel (int which
, bool do_cancel
)
203 if (!gomp_cancel_var
)
207 return ialias_call (GOMP_cancellation_point
) (which
);
209 struct gomp_thread
*thr
= gomp_thread ();
210 struct gomp_team
*team
= thr
->ts
.team
;
211 if (which
& (GOMP_CANCEL_LOOP
| GOMP_CANCEL_SECTIONS
))
213 /* In orphaned worksharing region, all we want to cancel
214 is current thread. */
216 team
->work_share_cancelled
= 1;
219 else if (which
& GOMP_CANCEL_TASKGROUP
)
221 if (thr
->task
->taskgroup
&& !thr
->task
->taskgroup
->cancelled
)
223 gomp_mutex_lock (&team
->task_lock
);
224 thr
->task
->taskgroup
->cancelled
= true;
225 gomp_mutex_unlock (&team
->task_lock
);
229 team
->team_cancelled
= 1;
230 gomp_team_barrier_cancel (team
);
234 /* The public OpenMP API for thread and team related inquiries. */
237 omp_get_num_threads (void)
239 struct gomp_team
*team
= gomp_thread ()->ts
.team
;
240 return team
? team
->nthreads
: 1;
244 omp_get_thread_num (void)
246 return gomp_thread ()->ts
.team_id
;
249 /* This wasn't right for OpenMP 2.5. Active region used to be non-zero
250 when the IF clause doesn't evaluate to false, starting with OpenMP 3.0
251 it is non-zero with more than one thread in the team. */
254 omp_in_parallel (void)
256 return gomp_thread ()->ts
.active_level
> 0;
262 return gomp_thread ()->ts
.level
;
266 omp_get_ancestor_thread_num (int level
)
268 struct gomp_team_state
*ts
= &gomp_thread ()->ts
;
269 if (level
< 0 || level
> ts
->level
)
271 for (level
= ts
->level
- level
; level
> 0; --level
)
272 ts
= &ts
->team
->prev_ts
;
277 omp_get_team_size (int level
)
279 struct gomp_team_state
*ts
= &gomp_thread ()->ts
;
280 if (level
< 0 || level
> ts
->level
)
282 for (level
= ts
->level
- level
; level
> 0; --level
)
283 ts
= &ts
->team
->prev_ts
;
284 if (ts
->team
== NULL
)
287 return ts
->team
->nthreads
;
291 omp_get_active_level (void)
293 return gomp_thread ()->ts
.active_level
;
296 ialias (omp_get_num_threads
)
297 ialias (omp_get_thread_num
)
298 ialias (omp_in_parallel
)
299 ialias (omp_get_level
)
300 ialias (omp_get_ancestor_thread_num
)
301 ialias (omp_get_team_size
)
302 ialias (omp_get_active_level
)