1This is libgomp.info, produced by makeinfo version 6.7 from
2libgomp.texi.
3
4Copyright (C) 2006-2018 Free Software Foundation, Inc.
5
6   Permission is granted to copy, distribute and/or modify this document
7under the terms of the GNU Free Documentation License, Version 1.3 or
8any later version published by the Free Software Foundation; with the
9Invariant Sections being "Funding Free Software", the Front-Cover texts
10being (a) (see below), and with the Back-Cover Texts being (b) (see
11below).  A copy of the license is included in the section entitled "GNU
12Free Documentation License".
13
14   (a) The FSF's Front-Cover Text is:
15
16   A GNU Manual
17
18   (b) The FSF's Back-Cover Text is:
19
20   You have freedom to copy and modify this GNU Manual, like GNU
21software.  Copies published by the Free Software Foundation raise funds
22for GNU development.
23INFO-DIR-SECTION GNU Libraries
24START-INFO-DIR-ENTRY
25* libgomp: (libgomp).          GNU Offloading and Multi Processing Runtime Library.
26END-INFO-DIR-ENTRY
27
28   This manual documents libgomp, the GNU Offloading and Multi
29Processing Runtime library.  This is the GNU implementation of the
30OpenMP and OpenACC APIs for parallel and accelerator programming in
31C/C++ and Fortran.
32
33   Published by the Free Software Foundation 51 Franklin Street, Fifth
34Floor Boston, MA 02110-1301 USA
35
36   Copyright (C) 2006-2018 Free Software Foundation, Inc.
37
38   Permission is granted to copy, distribute and/or modify this document
39under the terms of the GNU Free Documentation License, Version 1.3 or
40any later version published by the Free Software Foundation; with the
41Invariant Sections being "Funding Free Software", the Front-Cover texts
42being (a) (see below), and with the Back-Cover Texts being (b) (see
43below).  A copy of the license is included in the section entitled "GNU
44Free Documentation License".
45
46   (a) The FSF's Front-Cover Text is:
47
48   A GNU Manual
49
50   (b) The FSF's Back-Cover Text is:
51
52   You have freedom to copy and modify this GNU Manual, like GNU
53software.  Copies published by the Free Software Foundation raise funds
54for GNU development.
55
56
57File: libgomp.info,  Node: Top,  Next: Enabling OpenMP,  Up: (dir)
58
59Introduction
60************
61
62This manual documents the usage of libgomp, the GNU Offloading and Multi
63Processing Runtime Library.  This includes the GNU implementation of the
64OpenMP (http://www.openmp.org) Application Programming Interface (API)
65for multi-platform shared-memory parallel programming in C/C++ and
66Fortran, and the GNU implementation of the OpenACC
67(https://www.openacc.org) Application Programming Interface (API) for
68offloading of code to accelerator devices in C/C++ and Fortran.
69
70   Originally, libgomp implemented the GNU OpenMP Runtime Library.
71Based on this, support for OpenACC and offloading (both OpenACC and
72OpenMP 4's target construct) has been added later on, and the library's
73name changed to GNU Offloading and Multi Processing Runtime Library.
74
75* Menu:
76
77* Enabling OpenMP::            How to enable OpenMP for your applications.
78* Runtime Library Routines::   The OpenMP runtime application programming
79                               interface.
80* Environment Variables::      Influencing runtime behavior with environment
81                               variables.
82* Enabling OpenACC::           How to enable OpenACC for your
83                               applications.
84* OpenACC Runtime Library Routines:: The OpenACC runtime application
85                               programming interface.
86* OpenACC Environment Variables:: Influencing OpenACC runtime behavior with
87                               environment variables.
88* CUDA Streams Usage::         Notes on the implementation of
89                               asynchronous operations.
90* OpenACC Library Interoperability:: OpenACC library interoperability with the
91                               NVIDIA CUBLAS library.
92* The libgomp ABI::            Notes on the external ABI presented by libgomp.
93* Reporting Bugs::             How to report bugs in the GNU Offloading and
94                               Multi Processing Runtime Library.
95* Copying::                    GNU general public license says
96                               how you can copy and share libgomp.
97* GNU Free Documentation License::
98                               How you can copy and share this manual.
99* Funding::                    How to help assure continued work for free
100                               software.
101* Library Index::              Index of this documentation.
102
103
104File: libgomp.info,  Node: Enabling OpenMP,  Next: Runtime Library Routines,  Prev: Top,  Up: Top
105
1061 Enabling OpenMP
107*****************
108
109To activate the OpenMP extensions for C/C++ and Fortran, the
110compile-time flag '-fopenmp' must be specified.  This enables the OpenMP
111directive '#pragma omp' in C/C++ and '!$omp' directives in free form,
112'c$omp', '*$omp' and '!$omp' directives in fixed form, '!$' conditional
113compilation sentinels in free form and 'c$', '*$' and '!$' sentinels in
114fixed form, for Fortran.  The flag also arranges for automatic linking
115of the OpenMP runtime library (*note Runtime Library Routines::).
116
117   A complete description of all OpenMP directives accepted may be found
118in the OpenMP Application Program Interface (http://www.openmp.org)
119manual, version 4.5.
120
121
122File: libgomp.info,  Node: Runtime Library Routines,  Next: Environment Variables,  Prev: Enabling OpenMP,  Up: Top
123
1242 Runtime Library Routines
125**************************
126
127The runtime routines described here are defined by Section 3 of the
128OpenMP specification in version 4.5.  The routines are structured in
129following three parts:
130
131* Menu:
132
133Control threads, processors and the parallel environment.  They have C
134linkage, and do not throw exceptions.
135
136* omp_get_active_level::        Number of active parallel regions
137* omp_get_ancestor_thread_num:: Ancestor thread ID
138* omp_get_cancellation::        Whether cancellation support is enabled
139* omp_get_default_device::      Get the default device for target regions
140* omp_get_dynamic::             Dynamic teams setting
141* omp_get_level::               Number of parallel regions
142* omp_get_max_active_levels::   Maximum number of active regions
143* omp_get_max_task_priority::   Maximum task priority value that can be set
144* omp_get_max_threads::         Maximum number of threads of parallel region
145* omp_get_nested::              Nested parallel regions
146* omp_get_num_devices::         Number of target devices
147* omp_get_num_procs::           Number of processors online
148* omp_get_num_teams::           Number of teams
149* omp_get_num_threads::         Size of the active team
150* omp_get_proc_bind::           Whether theads may be moved between CPUs
151* omp_get_schedule::            Obtain the runtime scheduling method
152* omp_get_team_num::            Get team number
153* omp_get_team_size::           Number of threads in a team
154* omp_get_thread_limit::        Maximum number of threads
155* omp_get_thread_num::          Current thread ID
156* omp_in_parallel::             Whether a parallel region is active
157* omp_in_final::                Whether in final or included task region
158* omp_is_initial_device::       Whether executing on the host device
159* omp_set_default_device::      Set the default device for target regions
160* omp_set_dynamic::             Enable/disable dynamic teams
161* omp_set_max_active_levels::   Limits the number of active parallel regions
162* omp_set_nested::              Enable/disable nested parallel regions
163* omp_set_num_threads::         Set upper team size limit
164* omp_set_schedule::            Set the runtime scheduling method
165
166Initialize, set, test, unset and destroy simple and nested locks.
167
168* omp_init_lock::            Initialize simple lock
169* omp_set_lock::             Wait for and set simple lock
170* omp_test_lock::            Test and set simple lock if available
171* omp_unset_lock::           Unset simple lock
172* omp_destroy_lock::         Destroy simple lock
173* omp_init_nest_lock::       Initialize nested lock
174* omp_set_nest_lock::        Wait for and set simple lock
175* omp_test_nest_lock::       Test and set nested lock if available
176* omp_unset_nest_lock::      Unset nested lock
177* omp_destroy_nest_lock::    Destroy nested lock
178
179Portable, thread-based, wall clock timer.
180
181* omp_get_wtick::            Get timer precision.
182* omp_get_wtime::            Elapsed wall clock time.
183
184
185File: libgomp.info,  Node: omp_get_active_level,  Next: omp_get_ancestor_thread_num,  Up: Runtime Library Routines
186
1872.1 'omp_get_active_level' - Number of parallel regions
188=======================================================
189
190_Description_:
191     This function returns the nesting level for the active parallel
192     blocks, which enclose the calling call.
193
194_C/C++_
195     _Prototype_:   'int omp_get_active_level(void);'
196
197_Fortran_:
198     _Interface_:   'integer function omp_get_active_level()'
199
200_See also_:
201     *note omp_get_level::, *note omp_get_max_active_levels::, *note
202     omp_set_max_active_levels::
203
204_Reference_:
205     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.20.
206
207
208File: libgomp.info,  Node: omp_get_ancestor_thread_num,  Next: omp_get_cancellation,  Prev: omp_get_active_level,  Up: Runtime Library Routines
209
2102.2 'omp_get_ancestor_thread_num' - Ancestor thread ID
211======================================================
212
213_Description_:
214     This function returns the thread identification number for the
215     given nesting level of the current thread.  For values of LEVEL
216     outside zero to 'omp_get_level' -1 is returned; if LEVEL is
217     'omp_get_level' the result is identical to 'omp_get_thread_num'.
218
219_C/C++_
220     _Prototype_:   'int omp_get_ancestor_thread_num(int level);'
221
222_Fortran_:
223     _Interface_:   'integer function omp_get_ancestor_thread_num(level)'
224                    'integer level'
225
226_See also_:
227     *note omp_get_level::, *note omp_get_thread_num::, *note
228     omp_get_team_size::
229
230_Reference_:
231     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.18.
232
233
234File: libgomp.info,  Node: omp_get_cancellation,  Next: omp_get_default_device,  Prev: omp_get_ancestor_thread_num,  Up: Runtime Library Routines
235
2362.3 'omp_get_cancellation' - Whether cancellation support is enabled
237====================================================================
238
239_Description_:
240     This function returns 'true' if cancellation is activated, 'false'
241     otherwise.  Here, 'true' and 'false' represent their
242     language-specific counterparts.  Unless 'OMP_CANCELLATION' is set
243     true, cancellations are deactivated.
244
245_C/C++_:
246     _Prototype_:   'int omp_get_cancellation(void);'
247
248_Fortran_:
249     _Interface_:   'logical function omp_get_cancellation()'
250
251_See also_:
252     *note OMP_CANCELLATION::
253
254_Reference_:
255     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.9.
256
257
258File: libgomp.info,  Node: omp_get_default_device,  Next: omp_get_dynamic,  Prev: omp_get_cancellation,  Up: Runtime Library Routines
259
2602.4 'omp_get_default_device' - Get the default device for target regions
261========================================================================
262
263_Description_:
264     Get the default device for target regions without device clause.
265
266_C/C++_:
267     _Prototype_:   'int omp_get_default_device(void);'
268
269_Fortran_:
270     _Interface_:   'integer function omp_get_default_device()'
271
272_See also_:
273     *note OMP_DEFAULT_DEVICE::, *note omp_set_default_device::
274
275_Reference_:
276     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.30.
277
278
279File: libgomp.info,  Node: omp_get_dynamic,  Next: omp_get_level,  Prev: omp_get_default_device,  Up: Runtime Library Routines
280
2812.5 'omp_get_dynamic' - Dynamic teams setting
282=============================================
283
284_Description_:
285     This function returns 'true' if enabled, 'false' otherwise.  Here,
286     'true' and 'false' represent their language-specific counterparts.
287
288     The dynamic team setting may be initialized at startup by the
289     'OMP_DYNAMIC' environment variable or at runtime using
290     'omp_set_dynamic'.  If undefined, dynamic adjustment is disabled by
291     default.
292
293_C/C++_:
294     _Prototype_:   'int omp_get_dynamic(void);'
295
296_Fortran_:
297     _Interface_:   'logical function omp_get_dynamic()'
298
299_See also_:
300     *note omp_set_dynamic::, *note OMP_DYNAMIC::
301
302_Reference_:
303     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.8.
304
305
306File: libgomp.info,  Node: omp_get_level,  Next: omp_get_max_active_levels,  Prev: omp_get_dynamic,  Up: Runtime Library Routines
307
3082.6 'omp_get_level' - Obtain the current nesting level
309======================================================
310
311_Description_:
312     This function returns the nesting level for the parallel blocks,
313     which enclose the calling call.
314
315_C/C++_
316     _Prototype_:   'int omp_get_level(void);'
317
318_Fortran_:
319     _Interface_:   'integer function omp_level()'
320
321_See also_:
322     *note omp_get_active_level::
323
324_Reference_:
325     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.17.
326
327
328File: libgomp.info,  Node: omp_get_max_active_levels,  Next: omp_get_max_task_priority,  Prev: omp_get_level,  Up: Runtime Library Routines
329
3302.7 'omp_get_max_active_levels' - Maximum number of active regions
331==================================================================
332
333_Description_:
334     This function obtains the maximum allowed number of nested, active
335     parallel regions.
336
337_C/C++_
338     _Prototype_:   'int omp_get_max_active_levels(void);'
339
340_Fortran_:
341     _Interface_:   'integer function omp_get_max_active_levels()'
342
343_See also_:
344     *note omp_set_max_active_levels::, *note omp_get_active_level::
345
346_Reference_:
347     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.16.
348
349
350File: libgomp.info,  Node: omp_get_max_task_priority,  Next: omp_get_max_threads,  Prev: omp_get_max_active_levels,  Up: Runtime Library Routines
351
3522.8 'omp_get_max_task_priority' - Maximum priority value
353========================================================
354
355that can be set for tasks.
356_Description_:
357     This function obtains the maximum allowed priority number for
358     tasks.
359
360_C/C++_
361     _Prototype_:   'int omp_get_max_task_priority(void);'
362
363_Fortran_:
364     _Interface_:   'integer function omp_get_max_task_priority()'
365
366_Reference_:
367     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.29.
368
369
370File: libgomp.info,  Node: omp_get_max_threads,  Next: omp_get_nested,  Prev: omp_get_max_task_priority,  Up: Runtime Library Routines
371
3722.9 'omp_get_max_threads' - Maximum number of threads of parallel region
373========================================================================
374
375_Description_:
376     Return the maximum number of threads used for the current parallel
377     region that does not use the clause 'num_threads'.
378
379_C/C++_:
380     _Prototype_:   'int omp_get_max_threads(void);'
381
382_Fortran_:
383     _Interface_:   'integer function omp_get_max_threads()'
384
385_See also_:
386     *note omp_set_num_threads::, *note omp_set_dynamic::, *note
387     omp_get_thread_limit::
388
389_Reference_:
390     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.3.
391
392
393File: libgomp.info,  Node: omp_get_nested,  Next: omp_get_num_devices,  Prev: omp_get_max_threads,  Up: Runtime Library Routines
394
3952.10 'omp_get_nested' - Nested parallel regions
396===============================================
397
398_Description_:
399     This function returns 'true' if nested parallel regions are
400     enabled, 'false' otherwise.  Here, 'true' and 'false' represent
401     their language-specific counterparts.
402
403     Nested parallel regions may be initialized at startup by the
404     'OMP_NESTED' environment variable or at runtime using
405     'omp_set_nested'.  If undefined, nested parallel regions are
406     disabled by default.
407
408_C/C++_:
409     _Prototype_:   'int omp_get_nested(void);'
410
411_Fortran_:
412     _Interface_:   'logical function omp_get_nested()'
413
414_See also_:
415     *note omp_set_nested::, *note OMP_NESTED::
416
417_Reference_:
418     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.11.
419
420
421File: libgomp.info,  Node: omp_get_num_devices,  Next: omp_get_num_procs,  Prev: omp_get_nested,  Up: Runtime Library Routines
422
4232.11 'omp_get_num_devices' - Number of target devices
424=====================================================
425
426_Description_:
427     Returns the number of target devices.
428
429_C/C++_:
430     _Prototype_:   'int omp_get_num_devices(void);'
431
432_Fortran_:
433     _Interface_:   'integer function omp_get_num_devices()'
434
435_Reference_:
436     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.31.
437
438
439File: libgomp.info,  Node: omp_get_num_procs,  Next: omp_get_num_teams,  Prev: omp_get_num_devices,  Up: Runtime Library Routines
440
4412.12 'omp_get_num_procs' - Number of processors online
442======================================================
443
444_Description_:
445     Returns the number of processors online on that device.
446
447_C/C++_:
448     _Prototype_:   'int omp_get_num_procs(void);'
449
450_Fortran_:
451     _Interface_:   'integer function omp_get_num_procs()'
452
453_Reference_:
454     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.5.
455
456
457File: libgomp.info,  Node: omp_get_num_teams,  Next: omp_get_num_threads,  Prev: omp_get_num_procs,  Up: Runtime Library Routines
458
4592.13 'omp_get_num_teams' - Number of teams
460==========================================
461
462_Description_:
463     Returns the number of teams in the current team region.
464
465_C/C++_:
466     _Prototype_:   'int omp_get_num_teams(void);'
467
468_Fortran_:
469     _Interface_:   'integer function omp_get_num_teams()'
470
471_Reference_:
472     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.32.
473
474
475File: libgomp.info,  Node: omp_get_num_threads,  Next: omp_get_proc_bind,  Prev: omp_get_num_teams,  Up: Runtime Library Routines
476
4772.14 'omp_get_num_threads' - Size of the active team
478====================================================
479
480_Description_:
481     Returns the number of threads in the current team.  In a sequential
482     section of the program 'omp_get_num_threads' returns 1.
483
484     The default team size may be initialized at startup by the
485     'OMP_NUM_THREADS' environment variable.  At runtime, the size of
486     the current team may be set either by the 'NUM_THREADS' clause or
487     by 'omp_set_num_threads'.  If none of the above were used to define
488     a specific value and 'OMP_DYNAMIC' is disabled, one thread per CPU
489     online is used.
490
491_C/C++_:
492     _Prototype_:   'int omp_get_num_threads(void);'
493
494_Fortran_:
495     _Interface_:   'integer function omp_get_num_threads()'
496
497_See also_:
498     *note omp_get_max_threads::, *note omp_set_num_threads::, *note
499     OMP_NUM_THREADS::
500
501_Reference_:
502     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.2.
503
504
505File: libgomp.info,  Node: omp_get_proc_bind,  Next: omp_get_schedule,  Prev: omp_get_num_threads,  Up: Runtime Library Routines
506
5072.15 'omp_get_proc_bind' - Whether theads may be moved between CPUs
508===================================================================
509
510_Description_:
511     This functions returns the currently active thread affinity policy,
512     which is set via 'OMP_PROC_BIND'.  Possible values are
513     'omp_proc_bind_false', 'omp_proc_bind_true',
514     'omp_proc_bind_master', 'omp_proc_bind_close' and
515     'omp_proc_bind_spread'.
516
517_C/C++_:
518     _Prototype_:   'omp_proc_bind_t omp_get_proc_bind(void);'
519
520_Fortran_:
521     _Interface_:   'integer(kind=omp_proc_bind_kind) function
522                    omp_get_proc_bind()'
523
524_See also_:
525     *note OMP_PROC_BIND::, *note OMP_PLACES::, *note
526     GOMP_CPU_AFFINITY::,
527
528_Reference_:
529     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.22.
530
531
532File: libgomp.info,  Node: omp_get_schedule,  Next: omp_get_team_num,  Prev: omp_get_proc_bind,  Up: Runtime Library Routines
533
5342.16 'omp_get_schedule' - Obtain the runtime scheduling method
535==============================================================
536
537_Description_:
538     Obtain the runtime scheduling method.  The KIND argument will be
539     set to the value 'omp_sched_static', 'omp_sched_dynamic',
540     'omp_sched_guided' or 'omp_sched_auto'.  The second argument,
541     CHUNK_SIZE, is set to the chunk size.
542
543_C/C++_
544     _Prototype_:   'void omp_get_schedule(omp_sched_t *kind, int
545                    *chunk_size);'
546
547_Fortran_:
548     _Interface_:   'subroutine omp_get_schedule(kind, chunk_size)'
549                    'integer(kind=omp_sched_kind) kind'
550                    'integer chunk_size'
551
552_See also_:
553     *note omp_set_schedule::, *note OMP_SCHEDULE::
554
555_Reference_:
556     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.13.
557
558
559File: libgomp.info,  Node: omp_get_team_num,  Next: omp_get_team_size,  Prev: omp_get_schedule,  Up: Runtime Library Routines
560
5612.17 'omp_get_team_num' - Get team number
562=========================================
563
564_Description_:
565     Returns the team number of the calling thread.
566
567_C/C++_:
568     _Prototype_:   'int omp_get_team_num(void);'
569
570_Fortran_:
571     _Interface_:   'integer function omp_get_team_num()'
572
573_Reference_:
574     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.33.
575
576
577File: libgomp.info,  Node: omp_get_team_size,  Next: omp_get_thread_limit,  Prev: omp_get_team_num,  Up: Runtime Library Routines
578
5792.18 'omp_get_team_size' - Number of threads in a team
580======================================================
581
582_Description_:
583     This function returns the number of threads in a thread team to
584     which either the current thread or its ancestor belongs.  For
585     values of LEVEL outside zero to 'omp_get_level', -1 is returned; if
586     LEVEL is zero, 1 is returned, and for 'omp_get_level', the result
587     is identical to 'omp_get_num_threads'.
588
589_C/C++_:
590     _Prototype_:   'int omp_get_team_size(int level);'
591
592_Fortran_:
593     _Interface_:   'integer function omp_get_team_size(level)'
594                    'integer level'
595
596_See also_:
597     *note omp_get_num_threads::, *note omp_get_level::, *note
598     omp_get_ancestor_thread_num::
599
600_Reference_:
601     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.19.
602
603
604File: libgomp.info,  Node: omp_get_thread_limit,  Next: omp_get_thread_num,  Prev: omp_get_team_size,  Up: Runtime Library Routines
605
6062.19 'omp_get_thread_limit' - Maximum number of threads
607=======================================================
608
609_Description_:
610     Return the maximum number of threads of the program.
611
612_C/C++_:
613     _Prototype_:   'int omp_get_thread_limit(void);'
614
615_Fortran_:
616     _Interface_:   'integer function omp_get_thread_limit()'
617
618_See also_:
619     *note omp_get_max_threads::, *note OMP_THREAD_LIMIT::
620
621_Reference_:
622     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.14.
623
624
625File: libgomp.info,  Node: omp_get_thread_num,  Next: omp_in_parallel,  Prev: omp_get_thread_limit,  Up: Runtime Library Routines
626
6272.20 'omp_get_thread_num' - Current thread ID
628=============================================
629
630_Description_:
631     Returns a unique thread identification number within the current
632     team.  In a sequential parts of the program, 'omp_get_thread_num'
633     always returns 0.  In parallel regions the return value varies from
634     0 to 'omp_get_num_threads'-1 inclusive.  The return value of the
635     master thread of a team is always 0.
636
637_C/C++_:
638     _Prototype_:   'int omp_get_thread_num(void);'
639
640_Fortran_:
641     _Interface_:   'integer function omp_get_thread_num()'
642
643_See also_:
644     *note omp_get_num_threads::, *note omp_get_ancestor_thread_num::
645
646_Reference_:
647     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.4.
648
649
650File: libgomp.info,  Node: omp_in_parallel,  Next: omp_in_final,  Prev: omp_get_thread_num,  Up: Runtime Library Routines
651
6522.21 'omp_in_parallel' - Whether a parallel region is active
653============================================================
654
655_Description_:
656     This function returns 'true' if currently running in parallel,
657     'false' otherwise.  Here, 'true' and 'false' represent their
658     language-specific counterparts.
659
660_C/C++_:
661     _Prototype_:   'int omp_in_parallel(void);'
662
663_Fortran_:
664     _Interface_:   'logical function omp_in_parallel()'
665
666_Reference_:
667     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.6.
668
669
670File: libgomp.info,  Node: omp_in_final,  Next: omp_is_initial_device,  Prev: omp_in_parallel,  Up: Runtime Library Routines
671
6722.22 'omp_in_final' - Whether in final or included task region
673==============================================================
674
675_Description_:
676     This function returns 'true' if currently running in a final or
677     included task region, 'false' otherwise.  Here, 'true' and 'false'
678     represent their language-specific counterparts.
679
680_C/C++_:
681     _Prototype_:   'int omp_in_final(void);'
682
683_Fortran_:
684     _Interface_:   'logical function omp_in_final()'
685
686_Reference_:
687     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.21.
688
689
690File: libgomp.info,  Node: omp_is_initial_device,  Next: omp_set_default_device,  Prev: omp_in_final,  Up: Runtime Library Routines
691
6922.23 'omp_is_initial_device' - Whether executing on the host device
693===================================================================
694
695_Description_:
696     This function returns 'true' if currently running on the host
697     device, 'false' otherwise.  Here, 'true' and 'false' represent
698     their language-specific counterparts.
699
700_C/C++_:
701     _Prototype_:   'int omp_is_initial_device(void);'
702
703_Fortran_:
704     _Interface_:   'logical function omp_is_initial_device()'
705
706_Reference_:
707     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.34.
708
709
710File: libgomp.info,  Node: omp_set_default_device,  Next: omp_set_dynamic,  Prev: omp_is_initial_device,  Up: Runtime Library Routines
711
7122.24 'omp_set_default_device' - Set the default device for target regions
713=========================================================================
714
715_Description_:
716     Set the default device for target regions without device clause.
717     The argument shall be a nonnegative device number.
718
719_C/C++_:
720     _Prototype_:   'void omp_set_default_device(int device_num);'
721
722_Fortran_:
723     _Interface_:   'subroutine omp_set_default_device(device_num)'
724                    'integer device_num'
725
726_See also_:
727     *note OMP_DEFAULT_DEVICE::, *note omp_get_default_device::
728
729_Reference_:
730     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.29.
731
732
733File: libgomp.info,  Node: omp_set_dynamic,  Next: omp_set_max_active_levels,  Prev: omp_set_default_device,  Up: Runtime Library Routines
734
7352.25 'omp_set_dynamic' - Enable/disable dynamic teams
736=====================================================
737
738_Description_:
739     Enable or disable the dynamic adjustment of the number of threads
740     within a team.  The function takes the language-specific equivalent
741     of 'true' and 'false', where 'true' enables dynamic adjustment of
742     team sizes and 'false' disables it.
743
744_C/C++_:
745     _Prototype_:   'void omp_set_dynamic(int dynamic_threads);'
746
747_Fortran_:
748     _Interface_:   'subroutine omp_set_dynamic(dynamic_threads)'
749                    'logical, intent(in) :: dynamic_threads'
750
751_See also_:
752     *note OMP_DYNAMIC::, *note omp_get_dynamic::
753
754_Reference_:
755     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.7.
756
757
758File: libgomp.info,  Node: omp_set_max_active_levels,  Next: omp_set_nested,  Prev: omp_set_dynamic,  Up: Runtime Library Routines
759
7602.26 'omp_set_max_active_levels' - Limits the number of active parallel regions
761===============================================================================
762
763_Description_:
764     This function limits the maximum allowed number of nested, active
765     parallel regions.
766
767_C/C++_
768     _Prototype_:   'void omp_set_max_active_levels(int max_levels);'
769
770_Fortran_:
771     _Interface_:   'subroutine omp_set_max_active_levels(max_levels)'
772                    'integer max_levels'
773
774_See also_:
775     *note omp_get_max_active_levels::, *note omp_get_active_level::
776
777_Reference_:
778     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.15.
779
780
781File: libgomp.info,  Node: omp_set_nested,  Next: omp_set_num_threads,  Prev: omp_set_max_active_levels,  Up: Runtime Library Routines
782
7832.27 'omp_set_nested' - Enable/disable nested parallel regions
784==============================================================
785
786_Description_:
787     Enable or disable nested parallel regions, i.e., whether team
788     members are allowed to create new teams.  The function takes the
789     language-specific equivalent of 'true' and 'false', where 'true'
790     enables dynamic adjustment of team sizes and 'false' disables it.
791
792_C/C++_:
793     _Prototype_:   'void omp_set_nested(int nested);'
794
795_Fortran_:
796     _Interface_:   'subroutine omp_set_nested(nested)'
797                    'logical, intent(in) :: nested'
798
799_See also_:
800     *note OMP_NESTED::, *note omp_get_nested::
801
802_Reference_:
803     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.10.
804
805
806File: libgomp.info,  Node: omp_set_num_threads,  Next: omp_set_schedule,  Prev: omp_set_nested,  Up: Runtime Library Routines
807
8082.28 'omp_set_num_threads' - Set upper team size limit
809======================================================
810
811_Description_:
812     Specifies the number of threads used by default in subsequent
813     parallel sections, if those do not specify a 'num_threads' clause.
814     The argument of 'omp_set_num_threads' shall be a positive integer.
815
816_C/C++_:
817     _Prototype_:   'void omp_set_num_threads(int num_threads);'
818
819_Fortran_:
820     _Interface_:   'subroutine omp_set_num_threads(num_threads)'
821                    'integer, intent(in) :: num_threads'
822
823_See also_:
824     *note OMP_NUM_THREADS::, *note omp_get_num_threads::, *note
825     omp_get_max_threads::
826
827_Reference_:
828     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.1.
829
830
831File: libgomp.info,  Node: omp_set_schedule,  Next: omp_init_lock,  Prev: omp_set_num_threads,  Up: Runtime Library Routines
832
8332.29 'omp_set_schedule' - Set the runtime scheduling method
834===========================================================
835
836_Description_:
837     Sets the runtime scheduling method.  The KIND argument can have the
838     value 'omp_sched_static', 'omp_sched_dynamic', 'omp_sched_guided'
839     or 'omp_sched_auto'.  Except for 'omp_sched_auto', the chunk size
840     is set to the value of CHUNK_SIZE if positive, or to the default
841     value if zero or negative.  For 'omp_sched_auto' the CHUNK_SIZE
842     argument is ignored.
843
844_C/C++_
845     _Prototype_:   'void omp_set_schedule(omp_sched_t kind, int
846                    chunk_size);'
847
848_Fortran_:
849     _Interface_:   'subroutine omp_set_schedule(kind, chunk_size)'
850                    'integer(kind=omp_sched_kind) kind'
851                    'integer chunk_size'
852
853_See also_:
854     *note omp_get_schedule:: *note OMP_SCHEDULE::
855
856_Reference_:
857     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.2.12.
858
859
860File: libgomp.info,  Node: omp_init_lock,  Next: omp_set_lock,  Prev: omp_set_schedule,  Up: Runtime Library Routines
861
8622.30 'omp_init_lock' - Initialize simple lock
863=============================================
864
865_Description_:
866     Initialize a simple lock.  After initialization, the lock is in an
867     unlocked state.
868
869_C/C++_:
870     _Prototype_:   'void omp_init_lock(omp_lock_t *lock);'
871
872_Fortran_:
873     _Interface_:   'subroutine omp_init_lock(svar)'
874                    'integer(omp_lock_kind), intent(out) :: svar'
875
876_See also_:
877     *note omp_destroy_lock::
878
879_Reference_:
880     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.1.
881
882
883File: libgomp.info,  Node: omp_set_lock,  Next: omp_test_lock,  Prev: omp_init_lock,  Up: Runtime Library Routines
884
8852.31 'omp_set_lock' - Wait for and set simple lock
886==================================================
887
888_Description_:
889     Before setting a simple lock, the lock variable must be initialized
890     by 'omp_init_lock'.  The calling thread is blocked until the lock
891     is available.  If the lock is already held by the current thread, a
892     deadlock occurs.
893
894_C/C++_:
895     _Prototype_:   'void omp_set_lock(omp_lock_t *lock);'
896
897_Fortran_:
898     _Interface_:   'subroutine omp_set_lock(svar)'
899                    'integer(omp_lock_kind), intent(inout) :: svar'
900
901_See also_:
902     *note omp_init_lock::, *note omp_test_lock::, *note
903     omp_unset_lock::
904
905_Reference_:
906     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.4.
907
908
909File: libgomp.info,  Node: omp_test_lock,  Next: omp_unset_lock,  Prev: omp_set_lock,  Up: Runtime Library Routines
910
9112.32 'omp_test_lock' - Test and set simple lock if available
912============================================================
913
914_Description_:
915     Before setting a simple lock, the lock variable must be initialized
916     by 'omp_init_lock'.  Contrary to 'omp_set_lock', 'omp_test_lock'
917     does not block if the lock is not available.  This function returns
918     'true' upon success, 'false' otherwise.  Here, 'true' and 'false'
919     represent their language-specific counterparts.
920
921_C/C++_:
922     _Prototype_:   'int omp_test_lock(omp_lock_t *lock);'
923
924_Fortran_:
925     _Interface_:   'logical function omp_test_lock(svar)'
926                    'integer(omp_lock_kind), intent(inout) :: svar'
927
928_See also_:
929     *note omp_init_lock::, *note omp_set_lock::, *note omp_set_lock::
930
931_Reference_:
932     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.6.
933
934
935File: libgomp.info,  Node: omp_unset_lock,  Next: omp_destroy_lock,  Prev: omp_test_lock,  Up: Runtime Library Routines
936
9372.33 'omp_unset_lock' - Unset simple lock
938=========================================
939
940_Description_:
941     A simple lock about to be unset must have been locked by
942     'omp_set_lock' or 'omp_test_lock' before.  In addition, the lock
943     must be held by the thread calling 'omp_unset_lock'.  Then, the
944     lock becomes unlocked.  If one or more threads attempted to set the
945     lock before, one of them is chosen to, again, set the lock to
946     itself.
947
948_C/C++_:
949     _Prototype_:   'void omp_unset_lock(omp_lock_t *lock);'
950
951_Fortran_:
952     _Interface_:   'subroutine omp_unset_lock(svar)'
953                    'integer(omp_lock_kind), intent(inout) :: svar'
954
955_See also_:
956     *note omp_set_lock::, *note omp_test_lock::
957
958_Reference_:
959     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.5.
960
961
962File: libgomp.info,  Node: omp_destroy_lock,  Next: omp_init_nest_lock,  Prev: omp_unset_lock,  Up: Runtime Library Routines
963
9642.34 'omp_destroy_lock' - Destroy simple lock
965=============================================
966
967_Description_:
968     Destroy a simple lock.  In order to be destroyed, a simple lock
969     must be in the unlocked state.
970
971_C/C++_:
972     _Prototype_:   'void omp_destroy_lock(omp_lock_t *lock);'
973
974_Fortran_:
975     _Interface_:   'subroutine omp_destroy_lock(svar)'
976                    'integer(omp_lock_kind), intent(inout) :: svar'
977
978_See also_:
979     *note omp_init_lock::
980
981_Reference_:
982     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.3.
983
984
985File: libgomp.info,  Node: omp_init_nest_lock,  Next: omp_set_nest_lock,  Prev: omp_destroy_lock,  Up: Runtime Library Routines
986
9872.35 'omp_init_nest_lock' - Initialize nested lock
988==================================================
989
990_Description_:
991     Initialize a nested lock.  After initialization, the lock is in an
992     unlocked state and the nesting count is set to zero.
993
994_C/C++_:
995     _Prototype_:   'void omp_init_nest_lock(omp_nest_lock_t *lock);'
996
997_Fortran_:
998     _Interface_:   'subroutine omp_init_nest_lock(nvar)'
999                    'integer(omp_nest_lock_kind), intent(out) :: nvar'
1000
1001_See also_:
1002     *note omp_destroy_nest_lock::
1003
1004_Reference_:
1005     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.1.
1006
1007
1008File: libgomp.info,  Node: omp_set_nest_lock,  Next: omp_test_nest_lock,  Prev: omp_init_nest_lock,  Up: Runtime Library Routines
1009
10102.36 'omp_set_nest_lock' - Wait for and set nested lock
1011=======================================================
1012
1013_Description_:
1014     Before setting a nested lock, the lock variable must be initialized
1015     by 'omp_init_nest_lock'.  The calling thread is blocked until the
1016     lock is available.  If the lock is already held by the current
1017     thread, the nesting count for the lock is incremented.
1018
1019_C/C++_:
1020     _Prototype_:   'void omp_set_nest_lock(omp_nest_lock_t *lock);'
1021
1022_Fortran_:
1023     _Interface_:   'subroutine omp_set_nest_lock(nvar)'
1024                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'
1025
1026_See also_:
1027     *note omp_init_nest_lock::, *note omp_unset_nest_lock::
1028
1029_Reference_:
1030     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.4.
1031
1032
1033File: libgomp.info,  Node: omp_test_nest_lock,  Next: omp_unset_nest_lock,  Prev: omp_set_nest_lock,  Up: Runtime Library Routines
1034
10352.37 'omp_test_nest_lock' - Test and set nested lock if available
1036=================================================================
1037
1038_Description_:
1039     Before setting a nested lock, the lock variable must be initialized
1040     by 'omp_init_nest_lock'.  Contrary to 'omp_set_nest_lock',
1041     'omp_test_nest_lock' does not block if the lock is not available.
1042     If the lock is already held by the current thread, the new nesting
1043     count is returned.  Otherwise, the return value equals zero.
1044
1045_C/C++_:
1046     _Prototype_:   'int omp_test_nest_lock(omp_nest_lock_t *lock);'
1047
1048_Fortran_:
1049     _Interface_:   'logical function omp_test_nest_lock(nvar)'
1050                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'
1051
1052_See also_:
1053     *note omp_init_lock::, *note omp_set_lock::, *note omp_set_lock::
1054
1055_Reference_:
1056     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.6.
1057
1058
1059File: libgomp.info,  Node: omp_unset_nest_lock,  Next: omp_destroy_nest_lock,  Prev: omp_test_nest_lock,  Up: Runtime Library Routines
1060
10612.38 'omp_unset_nest_lock' - Unset nested lock
1062==============================================
1063
1064_Description_:
1065     A nested lock about to be unset must have been locked by
1066     'omp_set_nested_lock' or 'omp_test_nested_lock' before.  In
1067     addition, the lock must be held by the thread calling
1068     'omp_unset_nested_lock'.  If the nesting count drops to zero, the
1069     lock becomes unlocked.  If one ore more threads attempted to set
1070     the lock before, one of them is chosen to, again, set the lock to
1071     itself.
1072
1073_C/C++_:
1074     _Prototype_:   'void omp_unset_nest_lock(omp_nest_lock_t *lock);'
1075
1076_Fortran_:
1077     _Interface_:   'subroutine omp_unset_nest_lock(nvar)'
1078                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'
1079
1080_See also_:
1081     *note omp_set_nest_lock::
1082
1083_Reference_:
1084     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.5.
1085
1086
1087File: libgomp.info,  Node: omp_destroy_nest_lock,  Next: omp_get_wtick,  Prev: omp_unset_nest_lock,  Up: Runtime Library Routines
1088
10892.39 'omp_destroy_nest_lock' - Destroy nested lock
1090==================================================
1091
1092_Description_:
1093     Destroy a nested lock.  In order to be destroyed, a nested lock
1094     must be in the unlocked state and its nesting count must equal
1095     zero.
1096
1097_C/C++_:
1098     _Prototype_:   'void omp_destroy_nest_lock(omp_nest_lock_t *);'
1099
1100_Fortran_:
1101     _Interface_:   'subroutine omp_destroy_nest_lock(nvar)'
1102                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'
1103
1104_See also_:
1105     *note omp_init_lock::
1106
1107_Reference_:
1108     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.3.3.
1109
1110
1111File: libgomp.info,  Node: omp_get_wtick,  Next: omp_get_wtime,  Prev: omp_destroy_nest_lock,  Up: Runtime Library Routines
1112
11132.40 'omp_get_wtick' - Get timer precision
1114==========================================
1115
1116_Description_:
1117     Gets the timer precision, i.e., the number of seconds between two
1118     successive clock ticks.
1119
1120_C/C++_:
1121     _Prototype_:   'double omp_get_wtick(void);'
1122
1123_Fortran_:
1124     _Interface_:   'double precision function omp_get_wtick()'
1125
1126_See also_:
1127     *note omp_get_wtime::
1128
1129_Reference_:
1130     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.4.2.
1131
1132
1133File: libgomp.info,  Node: omp_get_wtime,  Prev: omp_get_wtick,  Up: Runtime Library Routines
1134
11352.41 'omp_get_wtime' - Elapsed wall clock time
1136==============================================
1137
1138_Description_:
1139     Elapsed wall clock time in seconds.  The time is measured per
1140     thread, no guarantee can be made that two distinct threads measure
1141     the same time.  Time is measured from some "time in the past",
1142     which is an arbitrary time guaranteed not to change during the
1143     execution of the program.
1144
1145_C/C++_:
1146     _Prototype_:   'double omp_get_wtime(void);'
1147
1148_Fortran_:
1149     _Interface_:   'double precision function omp_get_wtime()'
1150
1151_See also_:
1152     *note omp_get_wtick::
1153
1154_Reference_:
1155     OpenMP specification v4.5 (http://www.openmp.org/), Section 3.4.1.
1156
1157
1158File: libgomp.info,  Node: Environment Variables,  Next: Enabling OpenACC,  Prev: Runtime Library Routines,  Up: Top
1159
11603 Environment Variables
1161***********************
1162
1163The environment variables which beginning with 'OMP_' are defined by
1164section 4 of the OpenMP specification in version 4.5, while those
1165beginning with 'GOMP_' are GNU extensions.
1166
1167* Menu:
1168
1169* OMP_CANCELLATION::        Set whether cancellation is activated
1170* OMP_DISPLAY_ENV::         Show OpenMP version and environment variables
1171* OMP_DEFAULT_DEVICE::      Set the device used in target regions
1172* OMP_DYNAMIC::             Dynamic adjustment of threads
1173* OMP_MAX_ACTIVE_LEVELS::   Set the maximum number of nested parallel regions
1174* OMP_MAX_TASK_PRIORITY::   Set the maximum task priority value
1175* OMP_NESTED::              Nested parallel regions
1176* OMP_NUM_THREADS::         Specifies the number of threads to use
1177* OMP_PROC_BIND::           Whether theads may be moved between CPUs
1178* OMP_PLACES::              Specifies on which CPUs the theads should be placed
1179* OMP_STACKSIZE::           Set default thread stack size
1180* OMP_SCHEDULE::            How threads are scheduled
1181* OMP_THREAD_LIMIT::        Set the maximum number of threads
1182* OMP_WAIT_POLICY::         How waiting threads are handled
1183* GOMP_CPU_AFFINITY::       Bind threads to specific CPUs
1184* GOMP_DEBUG::              Enable debugging output
1185* GOMP_STACKSIZE::          Set default thread stack size
1186* GOMP_SPINCOUNT::          Set the busy-wait spin count
1187* GOMP_RTEMS_THREAD_POOLS:: Set the RTEMS specific thread pools
1188
1189
1190File: libgomp.info,  Node: OMP_CANCELLATION,  Next: OMP_DISPLAY_ENV,  Up: Environment Variables
1191
11923.1 'OMP_CANCELLATION' - Set whether cancellation is activated
1193==============================================================
1194
1195_Description_:
1196     If set to 'TRUE', the cancellation is activated.  If set to 'FALSE'
1197     or if unset, cancellation is disabled and the 'cancel' construct is
1198     ignored.
1199
1200_See also_:
1201     *note omp_get_cancellation::
1202
1203_Reference_:
1204     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.11
1205
1206
1207File: libgomp.info,  Node: OMP_DISPLAY_ENV,  Next: OMP_DEFAULT_DEVICE,  Prev: OMP_CANCELLATION,  Up: Environment Variables
1208
12093.2 'OMP_DISPLAY_ENV' - Show OpenMP version and environment variables
1210=====================================================================
1211
1212_Description_:
1213     If set to 'TRUE', the OpenMP version number and the values
1214     associated with the OpenMP environment variables are printed to
1215     'stderr'.  If set to 'VERBOSE', it additionally shows the value of
1216     the environment variables which are GNU extensions.  If undefined
1217     or set to 'FALSE', this information will not be shown.
1218
1219_Reference_:
1220     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.12
1221
1222
1223File: libgomp.info,  Node: OMP_DEFAULT_DEVICE,  Next: OMP_DYNAMIC,  Prev: OMP_DISPLAY_ENV,  Up: Environment Variables
1224
12253.3 'OMP_DEFAULT_DEVICE' - Set the device used in target regions
1226================================================================
1227
1228_Description_:
1229     Set to choose the device which is used in a 'target' region, unless
1230     the value is overridden by 'omp_set_default_device' or by a
1231     'device' clause.  The value shall be the nonnegative device number.
1232     If no device with the given device number exists, the code is
1233     executed on the host.  If unset, device number 0 will be used.
1234
1235_See also_:
1236     *note omp_get_default_device::, *note omp_set_default_device::,
1237
1238_Reference_:
1239     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.13
1240
1241
1242File: libgomp.info,  Node: OMP_DYNAMIC,  Next: OMP_MAX_ACTIVE_LEVELS,  Prev: OMP_DEFAULT_DEVICE,  Up: Environment Variables
1243
12443.4 'OMP_DYNAMIC' - Dynamic adjustment of threads
1245=================================================
1246
1247_Description_:
1248     Enable or disable the dynamic adjustment of the number of threads
1249     within a team.  The value of this environment variable shall be
1250     'TRUE' or 'FALSE'.  If undefined, dynamic adjustment is disabled by
1251     default.
1252
1253_See also_:
1254     *note omp_set_dynamic::
1255
1256_Reference_:
1257     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.3
1258
1259
1260File: libgomp.info,  Node: OMP_MAX_ACTIVE_LEVELS,  Next: OMP_MAX_TASK_PRIORITY,  Prev: OMP_DYNAMIC,  Up: Environment Variables
1261
12623.5 'OMP_MAX_ACTIVE_LEVELS' - Set the maximum number of nested parallel regions
1263===============================================================================
1264
1265_Description_:
1266     Specifies the initial value for the maximum number of nested
1267     parallel regions.  The value of this variable shall be a positive
1268     integer.  If undefined, the number of active levels is unlimited.
1269
1270_See also_:
1271     *note omp_set_max_active_levels::
1272
1273_Reference_:
1274     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.9
1275
1276
1277File: libgomp.info,  Node: OMP_MAX_TASK_PRIORITY,  Next: OMP_NESTED,  Prev: OMP_MAX_ACTIVE_LEVELS,  Up: Environment Variables
1278
12793.6 'OMP_MAX_TASK_PRIORITY' - Set the maximum priority
1280======================================================
1281
1282number that can be set for a task.
1283_Description_:
1284     Specifies the initial value for the maximum priority value that can
1285     be set for a task.  The value of this variable shall be a
1286     non-negative integer, and zero is allowed.  If undefined, the
1287     default priority is 0.
1288
1289_See also_:
1290     *note omp_get_max_task_priority::
1291
1292_Reference_:
1293     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.14
1294
1295
1296File: libgomp.info,  Node: OMP_NESTED,  Next: OMP_NUM_THREADS,  Prev: OMP_MAX_TASK_PRIORITY,  Up: Environment Variables
1297
12983.7 'OMP_NESTED' - Nested parallel regions
1299==========================================
1300
1301_Description_:
1302     Enable or disable nested parallel regions, i.e., whether team
1303     members are allowed to create new teams.  The value of this
1304     environment variable shall be 'TRUE' or 'FALSE'.  If undefined,
1305     nested parallel regions are disabled by default.
1306
1307_See also_:
1308     *note omp_set_nested::
1309
1310_Reference_:
1311     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.6
1312
1313
1314File: libgomp.info,  Node: OMP_NUM_THREADS,  Next: OMP_PROC_BIND,  Prev: OMP_NESTED,  Up: Environment Variables
1315
13163.8 'OMP_NUM_THREADS' - Specifies the number of threads to use
1317==============================================================
1318
1319_Description_:
1320     Specifies the default number of threads to use in parallel regions.
1321     The value of this variable shall be a comma-separated list of
1322     positive integers; the value specified the number of threads to use
1323     for the corresponding nested level.  If undefined one thread per
1324     CPU is used.
1325
1326_See also_:
1327     *note omp_set_num_threads::
1328
1329_Reference_:
1330     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.2
1331
1332
1333File: libgomp.info,  Node: OMP_PROC_BIND,  Next: OMP_PLACES,  Prev: OMP_NUM_THREADS,  Up: Environment Variables
1334
13353.9 'OMP_PROC_BIND' - Whether theads may be moved between CPUs
1336==============================================================
1337
1338_Description_:
1339     Specifies whether threads may be moved between processors.  If set
1340     to 'TRUE', OpenMP theads should not be moved; if set to 'FALSE'
1341     they may be moved.  Alternatively, a comma separated list with the
1342     values 'MASTER', 'CLOSE' and 'SPREAD' can be used to specify the
1343     thread affinity policy for the corresponding nesting level.  With
1344     'MASTER' the worker threads are in the same place partition as the
1345     master thread.  With 'CLOSE' those are kept close to the master
1346     thread in contiguous place partitions.  And with 'SPREAD' a sparse
1347     distribution across the place partitions is used.
1348
1349     When undefined, 'OMP_PROC_BIND' defaults to 'TRUE' when
1350     'OMP_PLACES' or 'GOMP_CPU_AFFINITY' is set and 'FALSE' otherwise.
1351
1352_See also_:
1353     *note OMP_PLACES::, *note GOMP_CPU_AFFINITY::, *note
1354     omp_get_proc_bind::
1355
1356_Reference_:
1357     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.4
1358
1359
1360File: libgomp.info,  Node: OMP_PLACES,  Next: OMP_STACKSIZE,  Prev: OMP_PROC_BIND,  Up: Environment Variables
1361
13623.10 'OMP_PLACES' - Specifies on which CPUs the theads should be placed
1363=======================================================================
1364
1365_Description_:
1366     The thread placement can be either specified using an abstract name
1367     or by an explicit list of the places.  The abstract names
1368     'threads', 'cores' and 'sockets' can be optionally followed by a
1369     positive number in parentheses, which denotes the how many places
1370     shall be created.  With 'threads' each place corresponds to a
1371     single hardware thread; 'cores' to a single core with the
1372     corresponding number of hardware threads; and with 'sockets' the
1373     place corresponds to a single socket.  The resulting placement can
1374     be shown by setting the 'OMP_DISPLAY_ENV' environment variable.
1375
1376     Alternatively, the placement can be specified explicitly as
1377     comma-separated list of places.  A place is specified by set of
1378     nonnegative numbers in curly braces, denoting the denoting the
1379     hardware threads.  The hardware threads belonging to a place can
1380     either be specified as comma-separated list of nonnegative thread
1381     numbers or using an interval.  Multiple places can also be either
1382     specified by a comma-separated list of places or by an interval.
1383     To specify an interval, a colon followed by the count is placed
1384     after after the hardware thread number or the place.  Optionally,
1385     the length can be followed by a colon and the stride number -
1386     otherwise a unit stride is assumed.  For instance, the following
1387     specifies the same places list: '"{0,1,2}, {3,4,6}, {7,8,9},
1388     {10,11,12}"'; '"{0:3}, {3:3}, {7:3}, {10:3}"'; and '"{0:2}:4:3"'.
1389
1390     If 'OMP_PLACES' and 'GOMP_CPU_AFFINITY' are unset and
1391     'OMP_PROC_BIND' is either unset or 'false', threads may be moved
1392     between CPUs following no placement policy.
1393
1394_See also_:
1395     *note OMP_PROC_BIND::, *note GOMP_CPU_AFFINITY::, *note
1396     omp_get_proc_bind::, *note OMP_DISPLAY_ENV::
1397
1398_Reference_:
1399     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.5
1400
1401
1402File: libgomp.info,  Node: OMP_STACKSIZE,  Next: OMP_SCHEDULE,  Prev: OMP_PLACES,  Up: Environment Variables
1403
14043.11 'OMP_STACKSIZE' - Set default thread stack size
1405====================================================
1406
1407_Description_:
1408     Set the default thread stack size in kilobytes, unless the number
1409     is suffixed by 'B', 'K', 'M' or 'G', in which case the size is,
1410     respectively, in bytes, kilobytes, megabytes or gigabytes.  This is
1411     different from 'pthread_attr_setstacksize' which gets the number of
1412     bytes as an argument.  If the stack size cannot be set due to
1413     system constraints, an error is reported and the initial stack size
1414     is left unchanged.  If undefined, the stack size is system
1415     dependent.
1416
1417_Reference_:
1418     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.7
1419
1420
1421File: libgomp.info,  Node: OMP_SCHEDULE,  Next: OMP_THREAD_LIMIT,  Prev: OMP_STACKSIZE,  Up: Environment Variables
1422
14233.12 'OMP_SCHEDULE' - How threads are scheduled
1424===============================================
1425
1426_Description_:
1427     Allows to specify 'schedule type' and 'chunk size'.  The value of
1428     the variable shall have the form: 'type[,chunk]' where 'type' is
1429     one of 'static', 'dynamic', 'guided' or 'auto' The optional 'chunk'
1430     size shall be a positive integer.  If undefined, dynamic scheduling
1431     and a chunk size of 1 is used.
1432
1433_See also_:
1434     *note omp_set_schedule::
1435
1436_Reference_:
1437     OpenMP specification v4.5 (http://www.openmp.org/), Sections
1438     2.7.1.1 and 4.1
1439
1440
1441File: libgomp.info,  Node: OMP_THREAD_LIMIT,  Next: OMP_WAIT_POLICY,  Prev: OMP_SCHEDULE,  Up: Environment Variables
1442
14433.13 'OMP_THREAD_LIMIT' - Set the maximum number of threads
1444===========================================================
1445
1446_Description_:
1447     Specifies the number of threads to use for the whole program.  The
1448     value of this variable shall be a positive integer.  If undefined,
1449     the number of threads is not limited.
1450
1451_See also_:
1452     *note OMP_NUM_THREADS::, *note omp_get_thread_limit::
1453
1454_Reference_:
1455     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.10
1456
1457
1458File: libgomp.info,  Node: OMP_WAIT_POLICY,  Next: GOMP_CPU_AFFINITY,  Prev: OMP_THREAD_LIMIT,  Up: Environment Variables
1459
14603.14 'OMP_WAIT_POLICY' - How waiting threads are handled
1461========================================================
1462
1463_Description_:
1464     Specifies whether waiting threads should be active or passive.  If
1465     the value is 'PASSIVE', waiting threads should not consume CPU
1466     power while waiting; while the value is 'ACTIVE' specifies that
1467     they should.  If undefined, threads wait actively for a short time
1468     before waiting passively.
1469
1470_See also_:
1471     *note GOMP_SPINCOUNT::
1472
1473_Reference_:
1474     OpenMP specification v4.5 (http://www.openmp.org/), Section 4.8
1475
1476
1477File: libgomp.info,  Node: GOMP_CPU_AFFINITY,  Next: GOMP_DEBUG,  Prev: OMP_WAIT_POLICY,  Up: Environment Variables
1478
14793.15 'GOMP_CPU_AFFINITY' - Bind threads to specific CPUs
1480========================================================
1481
1482_Description_:
1483     Binds threads to specific CPUs.  The variable should contain a
1484     space-separated or comma-separated list of CPUs.  This list may
1485     contain different kinds of entries: either single CPU numbers in
1486     any order, a range of CPUs (M-N) or a range with some stride
1487     (M-N:S). CPU numbers are zero based.  For example,
1488     'GOMP_CPU_AFFINITY="0 3 1-2 4-15:2"' will bind the initial thread
1489     to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to
1490     CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8,
1491     10, 12, and 14 respectively and then start assigning back from the
1492     beginning of the list.  'GOMP_CPU_AFFINITY=0' binds all threads to
1493     CPU 0.
1494
1495     There is no libgomp library routine to determine whether a CPU
1496     affinity specification is in effect.  As a workaround,
1497     language-specific library functions, e.g., 'getenv' in C or
1498     'GET_ENVIRONMENT_VARIABLE' in Fortran, may be used to query the
1499     setting of the 'GOMP_CPU_AFFINITY' environment variable.  A defined
1500     CPU affinity on startup cannot be changed or disabled during the
1501     runtime of the application.
1502
1503     If both 'GOMP_CPU_AFFINITY' and 'OMP_PROC_BIND' are set,
1504     'OMP_PROC_BIND' has a higher precedence.  If neither has been set
1505     and 'OMP_PROC_BIND' is unset, or when 'OMP_PROC_BIND' is set to
1506     'FALSE', the host system will handle the assignment of threads to
1507     CPUs.
1508
1509_See also_:
1510     *note OMP_PLACES::, *note OMP_PROC_BIND::
1511
1512
1513File: libgomp.info,  Node: GOMP_DEBUG,  Next: GOMP_STACKSIZE,  Prev: GOMP_CPU_AFFINITY,  Up: Environment Variables
1514
15153.16 'GOMP_DEBUG' - Enable debugging output
1516===========================================
1517
1518_Description_:
1519     Enable debugging output.  The variable should be set to '0'
1520     (disabled, also the default if not set), or '1' (enabled).
1521
1522     If enabled, some debugging output will be printed during execution.
1523     This is currently not specified in more detail, and subject to
1524     change.
1525
1526
1527File: libgomp.info,  Node: GOMP_STACKSIZE,  Next: GOMP_SPINCOUNT,  Prev: GOMP_DEBUG,  Up: Environment Variables
1528
15293.17 'GOMP_STACKSIZE' - Set default thread stack size
1530=====================================================
1531
1532_Description_:
1533     Set the default thread stack size in kilobytes.  This is different
1534     from 'pthread_attr_setstacksize' which gets the number of bytes as
1535     an argument.  If the stack size cannot be set due to system
1536     constraints, an error is reported and the initial stack size is
1537     left unchanged.  If undefined, the stack size is system dependent.
1538
1539_See also_:
1540     *note OMP_STACKSIZE::
1541
1542_Reference_:
1543     GCC Patches Mailinglist
1544     (http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00493.html), GCC
1545     Patches Mailinglist
1546     (http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00496.html)
1547
1548
1549File: libgomp.info,  Node: GOMP_SPINCOUNT,  Next: GOMP_RTEMS_THREAD_POOLS,  Prev: GOMP_STACKSIZE,  Up: Environment Variables
1550
15513.18 'GOMP_SPINCOUNT' - Set the busy-wait spin count
1552====================================================
1553
1554_Description_:
1555     Determines how long a threads waits actively with consuming CPU
1556     power before waiting passively without consuming CPU power.  The
1557     value may be either 'INFINITE', 'INFINITY' to always wait actively
1558     or an integer which gives the number of spins of the busy-wait
1559     loop.  The integer may optionally be followed by the following
1560     suffixes acting as multiplication factors: 'k' (kilo, thousand),
1561     'M' (mega, million), 'G' (giga, billion), or 'T' (tera, trillion).
1562     If undefined, 0 is used when 'OMP_WAIT_POLICY' is 'PASSIVE',
1563     300,000 is used when 'OMP_WAIT_POLICY' is undefined and 30 billion
1564     is used when 'OMP_WAIT_POLICY' is 'ACTIVE'.  If there are more
1565     OpenMP threads than available CPUs, 1000 and 100 spins are used for
1566     'OMP_WAIT_POLICY' being 'ACTIVE' or undefined, respectively; unless
1567     the 'GOMP_SPINCOUNT' is lower or 'OMP_WAIT_POLICY' is 'PASSIVE'.
1568
1569_See also_:
1570     *note OMP_WAIT_POLICY::
1571
1572
1573File: libgomp.info,  Node: GOMP_RTEMS_THREAD_POOLS,  Prev: GOMP_SPINCOUNT,  Up: Environment Variables
1574
15753.19 'GOMP_RTEMS_THREAD_POOLS' - Set the RTEMS specific thread pools
1576====================================================================
1577
1578_Description_:
1579     This environment variable is only used on the RTEMS real-time
1580     operating system.  It determines the scheduler instance specific
1581     thread pools.  The format for 'GOMP_RTEMS_THREAD_POOLS' is a list
1582     of optional '<thread-pool-count>[$<priority>]@<scheduler-name>'
1583     configurations separated by ':' where:
1584        * '<thread-pool-count>' is the thread pool count for this
1585          scheduler instance.
1586        * '$<priority>' is an optional priority for the worker threads
1587          of a thread pool according to 'pthread_setschedparam'.  In
1588          case a priority value is omitted, then a worker thread will
1589          inherit the priority of the OpenMP master thread that created
1590          it.  The priority of the worker thread is not changed after
1591          creation, even if a new OpenMP master thread using the worker
1592          has a different priority.
1593        * '@<scheduler-name>' is the scheduler instance name according
1594          to the RTEMS application configuration.
1595     In case no thread pool configuration is specified for a scheduler
1596     instance, then each OpenMP master thread of this scheduler instance
1597     will use its own dynamically allocated thread pool.  To limit the
1598     worker thread count of the thread pools, each OpenMP master thread
1599     must call 'omp_set_num_threads'.
1600_Example_:
1601     Lets suppose we have three scheduler instances 'IO', 'WRK0', and
1602     'WRK1' with 'GOMP_RTEMS_THREAD_POOLS' set to '"1@WRK0:3$4@WRK1"'.
1603     Then there are no thread pool restrictions for scheduler instance
1604     'IO'.  In the scheduler instance 'WRK0' there is one thread pool
1605     available.  Since no priority is specified for this scheduler
1606     instance, the worker thread inherits the priority of the OpenMP
1607     master thread that created it.  In the scheduler instance 'WRK1'
1608     there are three thread pools available and their worker threads run
1609     at priority four.
1610
1611
1612File: libgomp.info,  Node: Enabling OpenACC,  Next: OpenACC Runtime Library Routines,  Prev: Environment Variables,  Up: Top
1613
16144 Enabling OpenACC
1615******************
1616
1617To activate the OpenACC extensions for C/C++ and Fortran, the
1618compile-time flag '-fopenacc' must be specified.  This enables the
1619OpenACC directive '#pragma acc' in C/C++ and '!$accp' directives in free
1620form, 'c$acc', '*$acc' and '!$acc' directives in fixed form, '!$'
1621conditional compilation sentinels in free form and 'c$', '*$' and '!$'
1622sentinels in fixed form, for Fortran.  The flag also arranges for
1623automatic linking of the OpenACC runtime library (*note OpenACC Runtime
1624Library Routines::).
1625
1626   A complete description of all OpenACC directives accepted may be
1627found in the OpenACC (https://www.openacc.org) Application Programming
1628Interface manual, version 2.0.
1629
1630   Note that this is an experimental feature and subject to change in
1631future versions of GCC. See <https://gcc.gnu.org/wiki/OpenACC> for more
1632information.
1633
1634
1635File: libgomp.info,  Node: OpenACC Runtime Library Routines,  Next: OpenACC Environment Variables,  Prev: Enabling OpenACC,  Up: Top
1636
16375 OpenACC Runtime Library Routines
1638**********************************
1639
1640The runtime routines described here are defined by section 3 of the
1641OpenACC specifications in version 2.0.  They have C linkage, and do not
1642throw exceptions.  Generally, they are available only for the host, with
1643the exception of 'acc_on_device', which is available for both the host
1644and the acceleration device.
1645
1646* Menu:
1647
1648* acc_get_num_devices::         Get number of devices for the given device
1649                                type.
1650* acc_set_device_type::         Set type of device accelerator to use.
1651* acc_get_device_type::         Get type of device accelerator to be used.
1652* acc_set_device_num::          Set device number to use.
1653* acc_get_device_num::          Get device number to be used.
1654* acc_async_test::              Tests for completion of a specific asynchronous
1655                                operation.
1656* acc_async_test_all::          Tests for completion of all asychronous
1657                                operations.
1658* acc_wait::                    Wait for completion of a specific asynchronous
1659                                operation.
1660* acc_wait_all::                Waits for completion of all asyncrhonous
1661                                operations.
1662* acc_wait_all_async::          Wait for completion of all asynchronous
1663                                operations.
1664* acc_wait_async::              Wait for completion of asynchronous operations.
1665* acc_init::                    Initialize runtime for a specific device type.
1666* acc_shutdown::                Shuts down the runtime for a specific device
1667                                type.
1668* acc_on_device::               Whether executing on a particular device
1669* acc_malloc::                  Allocate device memory.
1670* acc_free::                    Free device memory.
1671* acc_copyin::                  Allocate device memory and copy host memory to
1672                                it.
1673* acc_present_or_copyin::       If the data is not present on the device,
1674                                allocate device memory and copy from host
1675                                memory.
1676* acc_create::                  Allocate device memory and map it to host
1677                                memory.
1678* acc_present_or_create::       If the data is not present on the device,
1679                                allocate device memory and map it to host
1680                                memory.
1681* acc_copyout::                 Copy device memory to host memory.
1682* acc_delete::                  Free device memory.
1683* acc_update_device::           Update device memory from mapped host memory.
1684* acc_update_self::             Update host memory from mapped device memory.
1685* acc_map_data::                Map previously allocated device memory to host
1686                                memory.
1687* acc_unmap_data::              Unmap device memory from host memory.
1688* acc_deviceptr::               Get device pointer associated with specific
1689                                host address.
1690* acc_hostptr::                 Get host pointer associated with specific
1691                                device address.
1692* acc_is_present::              Indiciate whether host variable / array is
1693                                present on device.
1694* acc_memcpy_to_device::        Copy host memory to device memory.
1695* acc_memcpy_from_device::      Copy device memory to host memory.
1696
1697API routines for target platforms.
1698
1699* acc_get_current_cuda_device:: Get CUDA device handle.
1700* acc_get_current_cuda_context::Get CUDA context handle.
1701* acc_get_cuda_stream::         Get CUDA stream handle.
1702* acc_set_cuda_stream::         Set CUDA stream handle.
1703
1704
1705File: libgomp.info,  Node: acc_get_num_devices,  Next: acc_set_device_type,  Up: OpenACC Runtime Library Routines
1706
17075.1 'acc_get_num_devices' - Get number of devices for given device type
1708=======================================================================
1709
1710_Description_
1711     This function returns a value indicating the number of devices
1712     available for the device type specified in DEVICETYPE.
1713
1714_C/C++_:
1715     _Prototype_:   'int acc_get_num_devices(acc_device_t devicetype);'
1716
1717_Fortran_:
1718     _Interface_:   'integer function acc_get_num_devices(devicetype)'
1719                    'integer(kind=acc_device_kind) devicetype'
1720
1721_Reference_:
1722     OpenACC specification v2.0 (https://www.openacc.org), section
1723     3.2.1.
1724
1725
1726File: libgomp.info,  Node: acc_set_device_type,  Next: acc_get_device_type,  Prev: acc_get_num_devices,  Up: OpenACC Runtime Library Routines
1727
17285.2 'acc_set_device_type' - Set type of device accelerator to use.
1729==================================================================
1730
1731_Description_
1732     This function indicates to the runtime library which device typr,
1733     specified in DEVICETYPE, to use when executing a parallel or
1734     kernels region.
1735
1736_C/C++_:
1737     _Prototype_:   'acc_set_device_type(acc_device_t devicetype);'
1738
1739_Fortran_:
1740     _Interface_:   'subroutine acc_set_device_type(devicetype)'
1741                    'integer(kind=acc_device_kind) devicetype'
1742
1743_Reference_:
1744     OpenACC specification v2.0 (https://www.openacc.org), section
1745     3.2.2.
1746
1747
1748File: libgomp.info,  Node: acc_get_device_type,  Next: acc_set_device_num,  Prev: acc_set_device_type,  Up: OpenACC Runtime Library Routines
1749
17505.3 'acc_get_device_type' - Get type of device accelerator to be used.
1751======================================================================
1752
1753_Description_
1754     This function returns what device type will be used when executing
1755     a parallel or kernels region.
1756
1757_C/C++_:
1758     _Prototype_:   'acc_device_t acc_get_device_type(void);'
1759
1760_Fortran_:
1761     _Interface_:   'function acc_get_device_type(void)'
1762                    'integer(kind=acc_device_kind) acc_get_device_type'
1763
1764_Reference_:
1765     OpenACC specification v2.0 (https://www.openacc.org), section
1766     3.2.3.
1767
1768
1769File: libgomp.info,  Node: acc_set_device_num,  Next: acc_get_device_num,  Prev: acc_get_device_type,  Up: OpenACC Runtime Library Routines
1770
17715.4 'acc_set_device_num' - Set device number to use.
1772====================================================
1773
1774_Description_
1775     This function will indicate to the runtime which device number,
1776     specified by NUM, associated with the specifed device type
1777     DEVICETYPE.
1778
1779_C/C++_:
1780     _Prototype_:   'acc_set_device_num(int num, acc_device_t devicetype);'
1781
1782_Fortran_:
1783     _Interface_:   'subroutine acc_set_device_num(devicenum, devicetype)'
1784                    'integer devicenum'
1785                    'integer(kind=acc_device_kind) devicetype'
1786
1787_Reference_:
1788     OpenACC specification v2.0 (https://www.openacc.org), section
1789     3.2.4.
1790
1791
1792File: libgomp.info,  Node: acc_get_device_num,  Next: acc_async_test,  Prev: acc_set_device_num,  Up: OpenACC Runtime Library Routines
1793
17945.5 'acc_get_device_num' - Get device number to be used.
1795========================================================
1796
1797_Description_
1798     This function returns which device number associated with the
1799     specified device type DEVICETYPE, will be used when executing a
1800     parallel or kernels region.
1801
1802_C/C++_:
1803     _Prototype_:   'int acc_get_device_num(acc_device_t devicetype);'
1804
1805_Fortran_:
1806     _Interface_:   'function acc_get_device_num(devicetype)'
1807                    'integer(kind=acc_device_kind) devicetype'
1808                    'integer acc_get_device_num'
1809
1810_Reference_:
1811     OpenACC specification v2.0 (https://www.openacc.org), section
1812     3.2.5.
1813
1814
1815File: libgomp.info,  Node: acc_async_test,  Next: acc_async_test_all,  Prev: acc_get_device_num,  Up: OpenACC Runtime Library Routines
1816
18175.6 'acc_async_test' - Test for completion of a specific asynchronous operation.
1818================================================================================
1819
1820_Description_
1821     This function tests for completion of the asynchrounous operation
1822     specified in ARG.  In C/C++, a non-zero value will be returned to
1823     indicate the specified asynchronous operation has completed.  While
1824     Fortran will return a 'true'.  If the asynchrounous operation has
1825     not completed, C/C++ returns a zero and Fortran returns a 'false'.
1826
1827_C/C++_:
1828     _Prototype_:   'int acc_async_test(int arg);'
1829
1830_Fortran_:
1831     _Interface_:   'function acc_async_test(arg)'
1832                    'integer(kind=acc_handle_kind) arg'
1833                    'logical acc_async_test'
1834
1835_Reference_:
1836     OpenACC specification v2.0 (https://www.openacc.org), section
1837     3.2.6.
1838
1839
1840File: libgomp.info,  Node: acc_async_test_all,  Next: acc_wait,  Prev: acc_async_test,  Up: OpenACC Runtime Library Routines
1841
18425.7 'acc_async_test_all' - Tests for completion of all asynchronous operations.
1843===============================================================================
1844
1845_Description_
1846     This function tests for completion of all asynchrounous operations.
1847     In C/C++, a non-zero value will be returned to indicate all
1848     asynchronous operations have completed.  While Fortran will return
1849     a 'true'.  If any asynchronous operation has not completed, C/C++
1850     returns a zero and Fortran returns a 'false'.
1851
1852_C/C++_:
1853     _Prototype_:   'int acc_async_test_all(void);'
1854
1855_Fortran_:
1856     _Interface_:   'function acc_async_test()'
1857                    'logical acc_get_device_num'
1858
1859_Reference_:
1860     OpenACC specification v2.0 (https://www.openacc.org), section
1861     3.2.7.
1862
1863
1864File: libgomp.info,  Node: acc_wait,  Next: acc_wait_all,  Prev: acc_async_test_all,  Up: OpenACC Runtime Library Routines
1865
18665.8 'acc_wait' - Wait for completion of a specific asynchronous operation.
1867==========================================================================
1868
1869_Description_
1870     This function waits for completion of the asynchronous operation
1871     specified in ARG.
1872
1873_C/C++_:
1874     _Prototype_:   'acc_wait(arg);'
1875     _Prototype     'acc_async_wait(arg);'
1876     (OpenACC 1.0
1877     compatibility)_:
1878
1879_Fortran_:
1880     _Interface_:   'subroutine acc_wait(arg)'
1881                    'integer(acc_handle_kind) arg'
1882     _Interface     'subroutine acc_async_wait(arg)'
1883     (OpenACC 1.0
1884     compatibility)_:
1885                    'integer(acc_handle_kind) arg'
1886
1887_Reference_:
1888     OpenACC specification v2.0 (https://www.openacc.org), section
1889     3.2.8.
1890
1891
1892File: libgomp.info,  Node: acc_wait_all,  Next: acc_wait_all_async,  Prev: acc_wait,  Up: OpenACC Runtime Library Routines
1893
18945.9 'acc_wait_all' - Waits for completion of all asynchronous operations.
1895=========================================================================
1896
1897_Description_
1898     This function waits for the completion of all asynchronous
1899     operations.
1900
1901_C/C++_:
1902     _Prototype_:   'acc_wait_all(void);'
1903     _Prototype     'acc_async_wait_all(void);'
1904     (OpenACC 1.0
1905     compatibility)_:
1906
1907_Fortran_:
1908     _Interface_:   'subroutine acc_wait_all()'
1909     _Interface     'subroutine acc_async_wait_all()'
1910     (OpenACC 1.0
1911     compatibility)_:
1912
1913_Reference_:
1914     OpenACC specification v2.0 (https://www.openacc.org), section
1915     3.2.10.
1916
1917
1918File: libgomp.info,  Node: acc_wait_all_async,  Next: acc_wait_async,  Prev: acc_wait_all,  Up: OpenACC Runtime Library Routines
1919
19205.10 'acc_wait_all_async' - Wait for completion of all asynchronous operations.
1921===============================================================================
1922
1923_Description_
1924     This function enqueues a wait operation on the queue ASYNC for any
1925     and all asynchronous operations that have been previously enqueued
1926     on any queue.
1927
1928_C/C++_:
1929     _Prototype_:   'acc_wait_all_async(int async);'
1930
1931_Fortran_:
1932     _Interface_:   'subroutine acc_wait_all_async(async)'
1933                    'integer(acc_handle_kind) async'
1934
1935_Reference_:
1936     OpenACC specification v2.0 (https://www.openacc.org), section
1937     3.2.11.
1938
1939
1940File: libgomp.info,  Node: acc_wait_async,  Next: acc_init,  Prev: acc_wait_all_async,  Up: OpenACC Runtime Library Routines
1941
19425.11 'acc_wait_async' - Wait for completion of asynchronous operations.
1943=======================================================================
1944
1945_Description_
1946     This function enqueues a wait operation on queue ASYNC for any and
1947     all asynchronous operations enqueued on queue ARG.
1948
1949_C/C++_:
1950     _Prototype_:   'acc_wait_async(int arg, int async);'
1951
1952_Fortran_:
1953     _Interface_:   'subroutine acc_wait_async(arg, async)'
1954                    'integer(acc_handle_kind) arg, async'
1955
1956_Reference_:
1957     OpenACC specification v2.0 (https://www.openacc.org), section
1958     3.2.9.
1959
1960
1961File: libgomp.info,  Node: acc_init,  Next: acc_shutdown,  Prev: acc_wait_async,  Up: OpenACC Runtime Library Routines
1962
19635.12 'acc_init' - Initialize runtime for a specific device type.
1964================================================================
1965
1966_Description_
1967     This function initializes the runtime for the device type specified
1968     in DEVICETYPE.
1969
1970_C/C++_:
1971     _Prototype_:   'acc_init(acc_device_t devicetype);'
1972
1973_Fortran_:
1974     _Interface_:   'subroutine acc_init(devicetype)'
1975                    'integer(acc_device_kind) devicetype'
1976
1977_Reference_:
1978     OpenACC specification v2.0 (https://www.openacc.org), section
1979     3.2.12.
1980
1981
1982File: libgomp.info,  Node: acc_shutdown,  Next: acc_on_device,  Prev: acc_init,  Up: OpenACC Runtime Library Routines
1983
19845.13 'acc_shutdown' - Shuts down the runtime for a specific device type.
1985========================================================================
1986
1987_Description_
1988     This function shuts down the runtime for the device type specified
1989     in DEVICETYPE.
1990
1991_C/C++_:
1992     _Prototype_:   'acc_shutdown(acc_device_t devicetype);'
1993
1994_Fortran_:
1995     _Interface_:   'subroutine acc_shutdown(devicetype)'
1996                    'integer(acc_device_kind) devicetype'
1997
1998_Reference_:
1999     OpenACC specification v2.0 (https://www.openacc.org), section
2000     3.2.13.
2001
2002
2003File: libgomp.info,  Node: acc_on_device,  Next: acc_malloc,  Prev: acc_shutdown,  Up: OpenACC Runtime Library Routines
2004
20055.14 'acc_on_device' - Whether executing on a particular device
2006===============================================================
2007
2008_Description_:
2009     This function returns whether the program is executing on a
2010     particular device specified in DEVICETYPE.  In C/C++ a non-zero
2011     value is returned to indicate the device is execiting on the
2012     specified device type.  In Fortran, 'true' will be returned.  If
2013     the program is not executing on the specified device type C/C++
2014     will return a zero, while Fortran will return 'false'.
2015
2016_C/C++_:
2017     _Prototype_:   'acc_on_device(acc_device_t devicetype);'
2018
2019_Fortran_:
2020     _Interface_:   'function acc_on_device(devicetype)'
2021                    'integer(acc_device_kind) devicetype'
2022                    'logical acc_on_device'
2023
2024_Reference_:
2025     OpenACC specification v2.0 (https://www.openacc.org), section
2026     3.2.14.
2027
2028
2029File: libgomp.info,  Node: acc_malloc,  Next: acc_free,  Prev: acc_on_device,  Up: OpenACC Runtime Library Routines
2030
20315.15 'acc_malloc' - Allocate device memory.
2032===========================================
2033
2034_Description_
2035     This function allocates LEN bytes of device memory.  It returns the
2036     device address of the allocated memory.
2037
2038_C/C++_:
2039     _Prototype_:   'd_void* acc_malloc(size_t len);'
2040
2041_Reference_:
2042     OpenACC specification v2.0 (https://www.openacc.org), section
2043     3.2.15.
2044
2045
2046File: libgomp.info,  Node: acc_free,  Next: acc_copyin,  Prev: acc_malloc,  Up: OpenACC Runtime Library Routines
2047
20485.16 'acc_free' - Free device memory.
2049=====================================
2050
2051_Description_
2052     Free previously allocated device memory at the device address 'a'.
2053
2054_C/C++_:
2055     _Prototype_:   'acc_free(d_void *a);'
2056
2057_Reference_:
2058     OpenACC specification v2.0 (https://www.openacc.org), section
2059     3.2.16.
2060
2061
2062File: libgomp.info,  Node: acc_copyin,  Next: acc_present_or_copyin,  Prev: acc_free,  Up: OpenACC Runtime Library Routines
2063
20645.17 'acc_copyin' - Allocate device memory and copy host memory to it.
2065======================================================================
2066
2067_Description_
2068     In C/C++, this function allocates LEN bytes of device memory and
2069     maps it to the specified host address in A.  The device address of
2070     the newly allocated device memory is returned.
2071
2072     In Fortran, two (2) forms are supported.  In the first form, A
2073     specifies a contiguous array section.  The second form A specifies
2074     a variable or array element and LEN specifies the length in bytes.
2075
2076_C/C++_:
2077     _Prototype_:   'void *acc_copyin(h_void *a, size_t len);'
2078
2079_Fortran_:
2080     _Interface_:   'subroutine acc_copyin(a)'
2081                    'type, dimension(:[,:]...) :: a'
2082     _Interface_:   'subroutine acc_copyin(a, len)'
2083                    'type, dimension(:[,:]...) :: a'
2084                    'integer len'
2085
2086_Reference_:
2087     OpenACC specification v2.0 (https://www.openacc.org), section
2088     3.2.17.
2089
2090
2091File: libgomp.info,  Node: acc_present_or_copyin,  Next: acc_create,  Prev: acc_copyin,  Up: OpenACC Runtime Library Routines
2092
20935.18 'acc_present_or_copyin' - If the data is not present on the device, allocate device memory and copy from host memory.
2094==========================================================================================================================
2095
2096_Description_
2097     This function tests if the host data specifed by A and of length
2098     LEN is present or not.  If it is not present, then device memory
2099     will be allocated and the host memory copied.  The device address
2100     of the newly allocated device memory is returned.
2101
2102     In Fortran, two (2) forms are supported.  In the first form, A
2103     specifies a contiguous array section.  The second form A specifies
2104     a variable or array element and LEN specifies the length in bytes.
2105
2106_C/C++_:
2107     _Prototype_:   'void *acc_present_or_copyin(h_void *a, size_t len);'
2108     _Prototype_:   'void *acc_pcopyin(h_void *a, size_t len);'
2109
2110_Fortran_:
2111     _Interface_:   'subroutine acc_present_or_copyin(a)'
2112                    'type, dimension(:[,:]...) :: a'
2113     _Interface_:   'subroutine acc_present_or_copyin(a, len)'
2114                    'type, dimension(:[,:]...) :: a'
2115                    'integer len'
2116     _Interface_:   'subroutine acc_pcopyin(a)'
2117                    'type, dimension(:[,:]...) :: a'
2118     _Interface_:   'subroutine acc_pcopyin(a, len)'
2119                    'type, dimension(:[,:]...) :: a'
2120                    'integer len'
2121
2122_Reference_:
2123     OpenACC specification v2.0 (https://www.openacc.org), section
2124     3.2.18.
2125
2126
2127File: libgomp.info,  Node: acc_create,  Next: acc_present_or_create,  Prev: acc_present_or_copyin,  Up: OpenACC Runtime Library Routines
2128
21295.19 'acc_create' - Allocate device memory and map it to host memory.
2130=====================================================================
2131
2132_Description_
2133     This function allocates device memory and maps it to host memory
2134     specified by the host address A with a length of LEN bytes.  In
2135     C/C++, the function returns the device address of the allocated
2136     device memory.
2137
2138     In Fortran, two (2) forms are supported.  In the first form, A
2139     specifies a contiguous array section.  The second form A specifies
2140     a variable or array element and LEN specifies the length in bytes.
2141
2142_C/C++_:
2143     _Prototype_:   'void *acc_create(h_void *a, size_t len);'
2144
2145_Fortran_:
2146     _Interface_:   'subroutine acc_create(a)'
2147                    'type, dimension(:[,:]...) :: a'
2148     _Interface_:   'subroutine acc_create(a, len)'
2149                    'type, dimension(:[,:]...) :: a'
2150                    'integer len'
2151
2152_Reference_:
2153     OpenACC specification v2.0 (https://www.openacc.org), section
2154     3.2.19.
2155
2156
2157File: libgomp.info,  Node: acc_present_or_create,  Next: acc_copyout,  Prev: acc_create,  Up: OpenACC Runtime Library Routines
2158
21595.20 'acc_present_or_create' - If the data is not present on the device, allocate device memory and map it to host memory.
2160==========================================================================================================================
2161
2162_Description_
2163     This function tests if the host data specifed by A and of length
2164     LEN is present or not.  If it is not present, then device memory
2165     will be allocated and mapped to host memory.  In C/C++, the device
2166     address of the newly allocated device memory is returned.
2167
2168     In Fortran, two (2) forms are supported.  In the first form, A
2169     specifies a contiguous array section.  The second form A specifies
2170     a variable or array element and LEN specifies the length in bytes.
2171
2172_C/C++_:
2173     _Prototype_:   'void *acc_present_or_create(h_void *a, size_t len)'
2174     _Prototype_:   'void *acc_pcreate(h_void *a, size_t len)'
2175
2176_Fortran_:
2177     _Interface_:   'subroutine acc_present_or_create(a)'
2178                    'type, dimension(:[,:]...) :: a'
2179     _Interface_:   'subroutine acc_present_or_create(a, len)'
2180                    'type, dimension(:[,:]...) :: a'
2181                    'integer len'
2182     _Interface_:   'subroutine acc_pcreate(a)'
2183                    'type, dimension(:[,:]...) :: a'
2184     _Interface_:   'subroutine acc_pcreate(a, len)'
2185                    'type, dimension(:[,:]...) :: a'
2186                    'integer len'
2187
2188_Reference_:
2189     OpenACC specification v2.0 (https://www.openacc.org), section
2190     3.2.20.
2191
2192
2193File: libgomp.info,  Node: acc_copyout,  Next: acc_delete,  Prev: acc_present_or_create,  Up: OpenACC Runtime Library Routines
2194
21955.21 'acc_copyout' - Copy device memory to host memory.
2196=======================================================
2197
2198_Description_
2199     This function copies mapped device memory to host memory which is
2200     specified by host address A for a length LEN bytes in C/C++.
2201
2202     In Fortran, two (2) forms are supported.  In the first form, A
2203     specifies a contiguous array section.  The second form A specifies
2204     a variable or array element and LEN specifies the length in bytes.
2205
2206_C/C++_:
2207     _Prototype_:   'acc_copyout(h_void *a, size_t len);'
2208
2209_Fortran_:
2210     _Interface_:   'subroutine acc_copyout(a)'
2211                    'type, dimension(:[,:]...) :: a'
2212     _Interface_:   'subroutine acc_copyout(a, len)'
2213                    'type, dimension(:[,:]...) :: a'
2214                    'integer len'
2215
2216_Reference_:
2217     OpenACC specification v2.0 (https://www.openacc.org), section
2218     3.2.21.
2219
2220
2221File: libgomp.info,  Node: acc_delete,  Next: acc_update_device,  Prev: acc_copyout,  Up: OpenACC Runtime Library Routines
2222
22235.22 'acc_delete' - Free device memory.
2224=======================================
2225
2226_Description_
2227     This function frees previously allocated device memory specified by
2228     the device address A and the length of LEN bytes.
2229
2230     In Fortran, two (2) forms are supported.  In the first form, A
2231     specifies a contiguous array section.  The second form A specifies
2232     a variable or array element and LEN specifies the length in bytes.
2233
2234_C/C++_:
2235     _Prototype_:   'acc_delete(h_void *a, size_t len);'
2236
2237_Fortran_:
2238     _Interface_:   'subroutine acc_delete(a)'
2239                    'type, dimension(:[,:]...) :: a'
2240     _Interface_:   'subroutine acc_delete(a, len)'
2241                    'type, dimension(:[,:]...) :: a'
2242                    'integer len'
2243
2244_Reference_:
2245     OpenACC specification v2.0 (https://www.openacc.org), section
2246     3.2.22.
2247
2248
2249File: libgomp.info,  Node: acc_update_device,  Next: acc_update_self,  Prev: acc_delete,  Up: OpenACC Runtime Library Routines
2250
22515.23 'acc_update_device' - Update device memory from mapped host memory.
2252========================================================================
2253
2254_Description_
2255     This function updates the device copy from the previously mapped
2256     host memory.  The host memory is specified with the host address A
2257     and a length of LEN bytes.
2258
2259     In Fortran, two (2) forms are supported.  In the first form, A
2260     specifies a contiguous array section.  The second form A specifies
2261     a variable or array element and LEN specifies the length in bytes.
2262
2263_C/C++_:
2264     _Prototype_:   'acc_update_device(h_void *a, size_t len);'
2265
2266_Fortran_:
2267     _Interface_:   'subroutine acc_update_device(a)'
2268                    'type, dimension(:[,:]...) :: a'
2269     _Interface_:   'subroutine acc_update_device(a, len)'
2270                    'type, dimension(:[,:]...) :: a'
2271                    'integer len'
2272
2273_Reference_:
2274     OpenACC specification v2.0 (https://www.openacc.org), section
2275     3.2.23.
2276
2277
2278File: libgomp.info,  Node: acc_update_self,  Next: acc_map_data,  Prev: acc_update_device,  Up: OpenACC Runtime Library Routines
2279
22805.24 'acc_update_self' - Update host memory from mapped device memory.
2281======================================================================
2282
2283_Description_
2284     This function updates the host copy from the previously mapped
2285     device memory.  The host memory is specified with the host address
2286     A and a length of LEN bytes.
2287
2288     In Fortran, two (2) forms are supported.  In the first form, A
2289     specifies a contiguous array section.  The second form A specifies
2290     a variable or array element and LEN specifies the length in bytes.
2291
2292_C/C++_:
2293     _Prototype_:   'acc_update_self(h_void *a, size_t len);'
2294
2295_Fortran_:
2296     _Interface_:   'subroutine acc_update_self(a)'
2297                    'type, dimension(:[,:]...) :: a'
2298     _Interface_:   'subroutine acc_update_self(a, len)'
2299                    'type, dimension(:[,:]...) :: a'
2300                    'integer len'
2301
2302_Reference_:
2303     OpenACC specification v2.0 (https://www.openacc.org), section
2304     3.2.24.
2305
2306
2307File: libgomp.info,  Node: acc_map_data,  Next: acc_unmap_data,  Prev: acc_update_self,  Up: OpenACC Runtime Library Routines
2308
23095.25 'acc_map_data' - Map previously allocated device memory to host memory.
2310============================================================================
2311
2312_Description_
2313     This function maps previously allocated device and host memory.
2314     The device memory is specified with the device address D.  The host
2315     memory is specified with the host address H and a length of LEN.
2316
2317_C/C++_:
2318     _Prototype_:   'acc_map_data(h_void *h, d_void *d, size_t len);'
2319
2320_Reference_:
2321     OpenACC specification v2.0 (https://www.openacc.org), section
2322     3.2.25.
2323
2324
2325File: libgomp.info,  Node: acc_unmap_data,  Next: acc_deviceptr,  Prev: acc_map_data,  Up: OpenACC Runtime Library Routines
2326
23275.26 'acc_unmap_data' - Unmap device memory from host memory.
2328=============================================================
2329
2330_Description_
2331     This function unmaps previously mapped device and host memory.  The
2332     latter specified by H.
2333
2334_C/C++_:
2335     _Prototype_:   'acc_unmap_data(h_void *h);'
2336
2337_Reference_:
2338     OpenACC specification v2.0 (https://www.openacc.org), section
2339     3.2.26.
2340
2341
2342File: libgomp.info,  Node: acc_deviceptr,  Next: acc_hostptr,  Prev: acc_unmap_data,  Up: OpenACC Runtime Library Routines
2343
23445.27 'acc_deviceptr' - Get device pointer associated with specific host address.
2345================================================================================
2346
2347_Description_
2348     This function returns the device address that has been mapped to
2349     the host address specified by H.
2350
2351_C/C++_:
2352     _Prototype_:   'void *acc_deviceptr(h_void *h);'
2353
2354_Reference_:
2355     OpenACC specification v2.0 (https://www.openacc.org), section
2356     3.2.27.
2357
2358
2359File: libgomp.info,  Node: acc_hostptr,  Next: acc_is_present,  Prev: acc_deviceptr,  Up: OpenACC Runtime Library Routines
2360
23615.28 'acc_hostptr' - Get host pointer associated with specific device address.
2362==============================================================================
2363
2364_Description_
2365     This function returns the host address that has been mapped to the
2366     device address specified by D.
2367
2368_C/C++_:
2369     _Prototype_:   'void *acc_hostptr(d_void *d);'
2370
2371_Reference_:
2372     OpenACC specification v2.0 (https://www.openacc.org), section
2373     3.2.28.
2374
2375
2376File: libgomp.info,  Node: acc_is_present,  Next: acc_memcpy_to_device,  Prev: acc_hostptr,  Up: OpenACC Runtime Library Routines
2377
23785.29 'acc_is_present' - Indicate whether host variable / array is present on device.
2379====================================================================================
2380
2381_Description_
2382     This function indicates whether the specified host address in A and
2383     a length of LEN bytes is present on the device.  In C/C++, a
2384     non-zero value is returned to indicate the presence of the mapped
2385     memory on the device.  A zero is returned to indicate the memory is
2386     not mapped on the device.
2387
2388     In Fortran, two (2) forms are supported.  In the first form, A
2389     specifies a contiguous array section.  The second form A specifies
2390     a variable or array element and LEN specifies the length in bytes.
2391     If the host memory is mapped to device memory, then a 'true' is
2392     returned.  Otherwise, a 'false' is return to indicate the mapped
2393     memory is not present.
2394
2395_C/C++_:
2396     _Prototype_:   'int acc_is_present(h_void *a, size_t len);'
2397
2398_Fortran_:
2399     _Interface_:   'function acc_is_present(a)'
2400                    'type, dimension(:[,:]...) :: a'
2401                    'logical acc_is_present'
2402     _Interface_:   'function acc_is_present(a, len)'
2403                    'type, dimension(:[,:]...) :: a'
2404                    'integer len'
2405                    'logical acc_is_present'
2406
2407_Reference_:
2408     OpenACC specification v2.0 (https://www.openacc.org), section
2409     3.2.29.
2410
2411
2412File: libgomp.info,  Node: acc_memcpy_to_device,  Next: acc_memcpy_from_device,  Prev: acc_is_present,  Up: OpenACC Runtime Library Routines
2413
24145.30 'acc_memcpy_to_device' - Copy host memory to device memory.
2415================================================================
2416
2417_Description_
2418     This function copies host memory specified by host address of SRC
2419     to device memory specified by the device address DEST for a length
2420     of BYTES bytes.
2421
2422_C/C++_:
2423     _Prototype_:   'acc_memcpy_to_device(d_void *dest, h_void *src, size_t
2424                    bytes);'
2425
2426_Reference_:
2427     OpenACC specification v2.0 (https://www.openacc.org), section
2428     3.2.30.
2429
2430
2431File: libgomp.info,  Node: acc_memcpy_from_device,  Next: acc_get_current_cuda_device,  Prev: acc_memcpy_to_device,  Up: OpenACC Runtime Library Routines
2432
24335.31 'acc_memcpy_from_device' - Copy device memory to host memory.
2434==================================================================
2435
2436_Description_
2437     This function copies host memory specified by host address of SRC
2438     from device memory specified by the device address DEST for a
2439     length of BYTES bytes.
2440
2441_C/C++_:
2442     _Prototype_:   'acc_memcpy_from_device(d_void *dest, h_void *src,
2443                    size_t bytes);'
2444
2445_Reference_:
2446     OpenACC specification v2.0 (https://www.openacc.org), section
2447     3.2.31.
2448
2449
2450File: libgomp.info,  Node: acc_get_current_cuda_device,  Next: acc_get_current_cuda_context,  Prev: acc_memcpy_from_device,  Up: OpenACC Runtime Library Routines
2451
24525.32 'acc_get_current_cuda_device' - Get CUDA device handle.
2453============================================================
2454
2455_Description_
2456     This function returns the CUDA device handle.  This handle is the
2457     same as used by the CUDA Runtime or Driver API's.
2458
2459_C/C++_:
2460     _Prototype_:   'void *acc_get_current_cuda_device(void);'
2461
2462_Reference_:
2463     OpenACC specification v2.0 (https://www.openacc.org), section
2464     A.2.1.1.
2465
2466
2467File: libgomp.info,  Node: acc_get_current_cuda_context,  Next: acc_get_cuda_stream,  Prev: acc_get_current_cuda_device,  Up: OpenACC Runtime Library Routines
2468
24695.33 'acc_get_current_cuda_context' - Get CUDA context handle.
2470==============================================================
2471
2472_Description_
2473     This function returns the CUDA context handle.  This handle is the
2474     same as used by the CUDA Runtime or Driver API's.
2475
2476_C/C++_:
2477     _Prototype_:   'acc_get_current_cuda_context(void);'
2478
2479_Reference_:
2480     OpenACC specification v2.0 (https://www.openacc.org), section
2481     A.2.1.2.
2482
2483
2484File: libgomp.info,  Node: acc_get_cuda_stream,  Next: acc_set_cuda_stream,  Prev: acc_get_current_cuda_context,  Up: OpenACC Runtime Library Routines
2485
24865.34 'acc_get_cuda_stream' - Get CUDA stream handle.
2487====================================================
2488
2489_Description_
2490     This function returns the CUDA stream handle.  This handle is the
2491     same as used by the CUDA Runtime or Driver API's.
2492
2493_C/C++_:
2494     _Prototype_:   'acc_get_cuda_stream(void);'
2495
2496_Reference_:
2497     OpenACC specification v2.0 (https://www.openacc.org), section
2498     A.2.1.3.
2499
2500
2501File: libgomp.info,  Node: acc_set_cuda_stream,  Prev: acc_get_cuda_stream,  Up: OpenACC Runtime Library Routines
2502
25035.35 'acc_set_cuda_stream' - Set CUDA stream handle.
2504====================================================
2505
2506_Description_
2507     This function associates the stream handle specified by STREAM with
2508     the asynchronous value specified by ASYNC.
2509
2510_C/C++_:
2511     _Prototype_:   'acc_set_cuda_stream(int async void *stream);'
2512
2513_Reference_:
2514     OpenACC specification v2.0 (https://www.openacc.org), section
2515     A.2.1.4.
2516
2517
2518File: libgomp.info,  Node: OpenACC Environment Variables,  Next: CUDA Streams Usage,  Prev: OpenACC Runtime Library Routines,  Up: Top
2519
25206 OpenACC Environment Variables
2521*******************************
2522
2523The variables 'ACC_DEVICE_TYPE' and 'ACC_DEVICE_NUM' are defined by
2524section 4 of the OpenACC specification in version 2.0.  The variable
2525'GCC_ACC_NOTIFY' is used for diagnostic purposes.
2526
2527* Menu:
2528
2529* ACC_DEVICE_TYPE::
2530* ACC_DEVICE_NUM::
2531* GCC_ACC_NOTIFY::
2532
2533
2534File: libgomp.info,  Node: ACC_DEVICE_TYPE,  Next: ACC_DEVICE_NUM,  Up: OpenACC Environment Variables
2535
25366.1 'ACC_DEVICE_TYPE'
2537=====================
2538
2539_Reference_:
2540     OpenACC specification v2.0 (https://www.openacc.org), section 4.1.
2541
2542
2543File: libgomp.info,  Node: ACC_DEVICE_NUM,  Next: GCC_ACC_NOTIFY,  Prev: ACC_DEVICE_TYPE,  Up: OpenACC Environment Variables
2544
25456.2 'ACC_DEVICE_NUM'
2546====================
2547
2548_Reference_:
2549     OpenACC specification v2.0 (https://www.openacc.org), section 4.2.
2550
2551
2552File: libgomp.info,  Node: GCC_ACC_NOTIFY,  Prev: ACC_DEVICE_NUM,  Up: OpenACC Environment Variables
2553
25546.3 'GCC_ACC_NOTIFY'
2555====================
2556
2557_Description_:
2558     Print debug information pertaining to the accelerator.
2559
2560
2561File: libgomp.info,  Node: CUDA Streams Usage,  Next: OpenACC Library Interoperability,  Prev: OpenACC Environment Variables,  Up: Top
2562
25637 CUDA Streams Usage
2564********************
2565
2566This applies to the 'nvptx' plugin only.
2567
2568   The library provides elements that perform asynchronous movement of
2569data and asynchronous operation of computing constructs.  This
2570asynchronous functionality is implemented by making use of CUDA
2571streams(1).
2572
2573   The primary means by that the asychronous functionality is accessed
2574is through the use of those OpenACC directives which make use of the
2575'async' and 'wait' clauses.  When the 'async' clause is first used with
2576a directive, it creates a CUDA stream.  If an 'async-argument' is used
2577with the 'async' clause, then the stream is associated with the
2578specified 'async-argument'.
2579
2580   Following the creation of an association between a CUDA stream and
2581the 'async-argument' of an 'async' clause, both the 'wait' clause and
2582the 'wait' directive can be used.  When either the clause or directive
2583is used after stream creation, it creates a rendezvous point whereby
2584execution waits until all operations associated with the
2585'async-argument', that is, stream, have completed.
2586
2587   Normally, the management of the streams that are created as a result
2588of using the 'async' clause, is done without any intervention by the
2589caller.  This implies the association between the 'async-argument' and
2590the CUDA stream will be maintained for the lifetime of the program.
2591However, this association can be changed through the use of the library
2592function 'acc_set_cuda_stream'.  When the function 'acc_set_cuda_stream'
2593is called, the CUDA stream that was originally associated with the
2594'async' clause will be destroyed.  Caution should be taken when changing
2595the association as subsequent references to the 'async-argument' refer
2596to a different CUDA stream.
2597
2598   ---------- Footnotes ----------
2599
2600   (1) See "Stream Management" in "CUDA Driver API", TRM-06703-001,
2601Version 5.5, for additional information
2602
2603
2604File: libgomp.info,  Node: OpenACC Library Interoperability,  Next: The libgomp ABI,  Prev: CUDA Streams Usage,  Up: Top
2605
26068 OpenACC Library Interoperability
2607**********************************
2608
26098.1 Introduction
2610================
2611
2612The OpenACC library uses the CUDA Driver API, and may interact with
2613programs that use the Runtime library directly, or another library based
2614on the Runtime library, e.g., CUBLAS(1). This chapter describes the use
2615cases and what changes are required in order to use both the OpenACC
2616library and the CUBLAS and Runtime libraries within a program.
2617
26188.2 First invocation: NVIDIA CUBLAS library API
2619===============================================
2620
2621In this first use case (see below), a function in the CUBLAS library is
2622called prior to any of the functions in the OpenACC library.  More
2623specifically, the function 'cublasCreate()'.
2624
2625   When invoked, the function initializes the library and allocates the
2626hardware resources on the host and the device on behalf of the caller.
2627Once the initialization and allocation has completed, a handle is
2628returned to the caller.  The OpenACC library also requires
2629initialization and allocation of hardware resources.  Since the CUBLAS
2630library has already allocated the hardware resources for the device, all
2631that is left to do is to initialize the OpenACC library and acquire the
2632hardware resources on the host.
2633
2634   Prior to calling the OpenACC function that initializes the library
2635and allocate the host hardware resources, you need to acquire the device
2636number that was allocated during the call to 'cublasCreate()'.  The
2637invoking of the runtime library function 'cudaGetDevice()' accomplishes
2638this.  Once acquired, the device number is passed along with the device
2639type as parameters to the OpenACC library function
2640'acc_set_device_num()'.
2641
2642   Once the call to 'acc_set_device_num()' has completed, the OpenACC
2643library uses the context that was created during the call to
2644'cublasCreate()'.  In other words, both libraries will be sharing the
2645same context.
2646
2647         /* Create the handle */
2648         s = cublasCreate(&h);
2649         if (s != CUBLAS_STATUS_SUCCESS)
2650         {
2651             fprintf(stderr, "cublasCreate failed %d\n", s);
2652             exit(EXIT_FAILURE);
2653         }
2654
2655         /* Get the device number */
2656         e = cudaGetDevice(&dev);
2657         if (e != cudaSuccess)
2658         {
2659             fprintf(stderr, "cudaGetDevice failed %d\n", e);
2660             exit(EXIT_FAILURE);
2661         }
2662
2663         /* Initialize OpenACC library and use device 'dev' */
2664         acc_set_device_num(dev, acc_device_nvidia);
2665
2666                              Use Case 1
2667
26688.3 First invocation: OpenACC library API
2669=========================================
2670
2671In this second use case (see below), a function in the OpenACC library
2672is called prior to any of the functions in the CUBLAS library.  More
2673specificially, the function 'acc_set_device_num()'.
2674
2675   In the use case presented here, the function 'acc_set_device_num()'
2676is used to both initialize the OpenACC library and allocate the hardware
2677resources on the host and the device.  In the call to the function, the
2678call parameters specify which device to use and what device type to use,
2679i.e., 'acc_device_nvidia'.  It should be noted that this is but one
2680method to initialize the OpenACC library and allocate the appropriate
2681hardware resources.  Other methods are available through the use of
2682environment variables and these will be discussed in the next section.
2683
2684   Once the call to 'acc_set_device_num()' has completed, other OpenACC
2685functions can be called as seen with multiple calls being made to
2686'acc_copyin()'.  In addition, calls can be made to functions in the
2687CUBLAS library.  In the use case a call to 'cublasCreate()' is made
2688subsequent to the calls to 'acc_copyin()'.  As seen in the previous use
2689case, a call to 'cublasCreate()' initializes the CUBLAS library and
2690allocates the hardware resources on the host and the device.  However,
2691since the device has already been allocated, 'cublasCreate()' will only
2692initialize the CUBLAS library and allocate the appropriate hardware
2693resources on the host.  The context that was created as part of the
2694OpenACC initialization is shared with the CUBLAS library, similarly to
2695the first use case.
2696
2697         dev = 0;
2698
2699         acc_set_device_num(dev, acc_device_nvidia);
2700
2701         /* Copy the first set to the device */
2702         d_X = acc_copyin(&h_X[0], N * sizeof (float));
2703         if (d_X == NULL)
2704         {
2705             fprintf(stderr, "copyin error h_X\n");
2706             exit(EXIT_FAILURE);
2707         }
2708
2709         /* Copy the second set to the device */
2710         d_Y = acc_copyin(&h_Y1[0], N * sizeof (float));
2711         if (d_Y == NULL)
2712         {
2713             fprintf(stderr, "copyin error h_Y1\n");
2714             exit(EXIT_FAILURE);
2715         }
2716
2717         /* Create the handle */
2718         s = cublasCreate(&h);
2719         if (s != CUBLAS_STATUS_SUCCESS)
2720         {
2721             fprintf(stderr, "cublasCreate failed %d\n", s);
2722             exit(EXIT_FAILURE);
2723         }
2724
2725         /* Perform saxpy using CUBLAS library function */
2726         s = cublasSaxpy(h, N, &alpha, d_X, 1, d_Y, 1);
2727         if (s != CUBLAS_STATUS_SUCCESS)
2728         {
2729             fprintf(stderr, "cublasSaxpy failed %d\n", s);
2730             exit(EXIT_FAILURE);
2731         }
2732
2733         /* Copy the results from the device */
2734         acc_memcpy_from_device(&h_Y1[0], d_Y, N * sizeof (float));
2735
2736                              Use Case 2
2737
27388.4 OpenACC library and environment variables
2739=============================================
2740
2741There are two environment variables associated with the OpenACC library
2742that may be used to control the device type and device number:
2743'ACC_DEVICE_TYPE' and 'ACC_DEVICE_NUM', respecively.  These two
2744environement variables can be used as an alternative to calling
2745'acc_set_device_num()'.  As seen in the second use case, the device type
2746and device number were specified using 'acc_set_device_num()'.  If
2747however, the aforementioned environment variables were set, then the
2748call to 'acc_set_device_num()' would not be required.
2749
2750   The use of the environment variables is only relevant when an OpenACC
2751function is called prior to a call to 'cudaCreate()'.  If 'cudaCreate()'
2752is called prior to a call to an OpenACC function, then you must call
2753'acc_set_device_num()'(2)
2754
2755   ---------- Footnotes ----------
2756
2757   (1) See section 2.26, "Interactions with the CUDA Driver API" in
2758"CUDA Runtime API", Version 5.5, and section 2.27, "VDPAU
2759Interoperability", in "CUDA Driver API", TRM-06703-001, Version 5.5, for
2760additional information on library interoperability.
2761
2762   (2) More complete information about 'ACC_DEVICE_TYPE' and
2763'ACC_DEVICE_NUM' can be found in sections 4.1 and 4.2 of the OpenACC
2764(https://www.openacc.org) Application Programming Interface”, Version
27652.0.
2766
2767
2768File: libgomp.info,  Node: The libgomp ABI,  Next: Reporting Bugs,  Prev: OpenACC Library Interoperability,  Up: Top
2769
27709 The libgomp ABI
2771*****************
2772
2773The following sections present notes on the external ABI as presented by
2774libgomp.  Only maintainers should need them.
2775
2776* Menu:
2777
2778* Implementing MASTER construct::
2779* Implementing CRITICAL construct::
2780* Implementing ATOMIC construct::
2781* Implementing FLUSH construct::
2782* Implementing BARRIER construct::
2783* Implementing THREADPRIVATE construct::
2784* Implementing PRIVATE clause::
2785* Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses::
2786* Implementing REDUCTION clause::
2787* Implementing PARALLEL construct::
2788* Implementing FOR construct::
2789* Implementing ORDERED construct::
2790* Implementing SECTIONS construct::
2791* Implementing SINGLE construct::
2792* Implementing OpenACC's PARALLEL construct::
2793
2794
2795File: libgomp.info,  Node: Implementing MASTER construct,  Next: Implementing CRITICAL construct,  Up: The libgomp ABI
2796
27979.1 Implementing MASTER construct
2798=================================
2799
2800     if (omp_get_thread_num () == 0)
2801       block
2802
2803   Alternately, we generate two copies of the parallel subfunction and
2804only include this in the version run by the master thread.  Surely this
2805is not worthwhile though...
2806
2807
2808File: libgomp.info,  Node: Implementing CRITICAL construct,  Next: Implementing ATOMIC construct,  Prev: Implementing MASTER construct,  Up: The libgomp ABI
2809
28109.2 Implementing CRITICAL construct
2811===================================
2812
2813Without a specified name,
2814
2815       void GOMP_critical_start (void);
2816       void GOMP_critical_end (void);
2817
2818   so that we don't get COPY relocations from libgomp to the main
2819application.
2820
2821   With a specified name, use omp_set_lock and omp_unset_lock with name
2822being transformed into a variable declared like
2823
2824       omp_lock_t gomp_critical_user_<name> __attribute__((common))
2825
2826   Ideally the ABI would specify that all zero is a valid unlocked
2827state, and so we wouldn't need to initialize this at startup.
2828
2829
2830File: libgomp.info,  Node: Implementing ATOMIC construct,  Next: Implementing FLUSH construct,  Prev: Implementing CRITICAL construct,  Up: The libgomp ABI
2831
28329.3 Implementing ATOMIC construct
2833=================================
2834
2835The target should implement the '__sync' builtins.
2836
2837   Failing that we could add
2838
2839       void GOMP_atomic_enter (void)
2840       void GOMP_atomic_exit (void)
2841
2842   which reuses the regular lock code, but with yet another lock object
2843private to the library.
2844
2845
2846File: libgomp.info,  Node: Implementing FLUSH construct,  Next: Implementing BARRIER construct,  Prev: Implementing ATOMIC construct,  Up: The libgomp ABI
2847
28489.4 Implementing FLUSH construct
2849================================
2850
2851Expands to the '__sync_synchronize' builtin.
2852
2853
2854File: libgomp.info,  Node: Implementing BARRIER construct,  Next: Implementing THREADPRIVATE construct,  Prev: Implementing FLUSH construct,  Up: The libgomp ABI
2855
28569.5 Implementing BARRIER construct
2857==================================
2858
2859       void GOMP_barrier (void)
2860
2861
2862File: libgomp.info,  Node: Implementing THREADPRIVATE construct,  Next: Implementing PRIVATE clause,  Prev: Implementing BARRIER construct,  Up: The libgomp ABI
2863
28649.6 Implementing THREADPRIVATE construct
2865========================================
2866
2867In _most_ cases we can map this directly to '__thread'.  Except that OMP
2868allows constructors for C++ objects.  We can either refuse to support
2869this (how often is it used?)  or we can implement something akin to
2870.ctors.
2871
2872   Even more ideally, this ctor feature is handled by extensions to the
2873main pthreads library.  Failing that, we can have a set of entry points
2874to register ctor functions to be called.
2875
2876
2877File: libgomp.info,  Node: Implementing PRIVATE clause,  Next: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Prev: Implementing THREADPRIVATE construct,  Up: The libgomp ABI
2878
28799.7 Implementing PRIVATE clause
2880===============================
2881
2882In association with a PARALLEL, or within the lexical extent of a
2883PARALLEL block, the variable becomes a local variable in the parallel
2884subfunction.
2885
2886   In association with FOR or SECTIONS blocks, create a new automatic
2887variable within the current function.  This preserves the semantic of
2888new variable creation.
2889
2890
2891File: libgomp.info,  Node: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Next: Implementing REDUCTION clause,  Prev: Implementing PRIVATE clause,  Up: The libgomp ABI
2892
28939.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses
2894========================================================================
2895
2896This seems simple enough for PARALLEL blocks.  Create a private struct
2897for communicating between the parent and subfunction.  In the parent,
2898copy in values for scalar and "small" structs; copy in addresses for
2899others TREE_ADDRESSABLE types.  In the subfunction, copy the value into
2900the local variable.
2901
2902   It is not clear what to do with bare FOR or SECTION blocks.  The only
2903thing I can figure is that we do something like:
2904
2905     #pragma omp for firstprivate(x) lastprivate(y)
2906     for (int i = 0; i < n; ++i)
2907       body;
2908
2909   which becomes
2910
2911     {
2912       int x = x, y;
2913
2914       // for stuff
2915
2916       if (i == n)
2917         y = y;
2918     }
2919
2920   where the "x=x" and "y=y" assignments actually have different uids
2921for the two variables, i.e.  not something you could write directly in
2922C. Presumably this only makes sense if the "outer" x and y are global
2923variables.
2924
2925   COPYPRIVATE would work the same way, except the structure broadcast
2926would have to happen via SINGLE machinery instead.
2927
2928
2929File: libgomp.info,  Node: Implementing REDUCTION clause,  Next: Implementing PARALLEL construct,  Prev: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Up: The libgomp ABI
2930
29319.9 Implementing REDUCTION clause
2932=================================
2933
2934The private struct mentioned in the previous section should have a
2935pointer to an array of the type of the variable, indexed by the thread's
2936TEAM_ID.  The thread stores its final value into the array, and after
2937the barrier, the master thread iterates over the array to collect the
2938values.
2939
2940
2941File: libgomp.info,  Node: Implementing PARALLEL construct,  Next: Implementing FOR construct,  Prev: Implementing REDUCTION clause,  Up: The libgomp ABI
2942
29439.10 Implementing PARALLEL construct
2944====================================
2945
2946       #pragma omp parallel
2947       {
2948         body;
2949       }
2950
2951   becomes
2952
2953       void subfunction (void *data)
2954       {
2955         use data;
2956         body;
2957       }
2958
2959       setup data;
2960       GOMP_parallel_start (subfunction, &data, num_threads);
2961       subfunction (&data);
2962       GOMP_parallel_end ();
2963
2964       void GOMP_parallel_start (void (*fn)(void *), void *data, unsigned num_threads)
2965
2966   The FN argument is the subfunction to be run in parallel.
2967
2968   The DATA argument is a pointer to a structure used to communicate
2969data in and out of the subfunction, as discussed above with respect to
2970FIRSTPRIVATE et al.
2971
2972   The NUM_THREADS argument is 1 if an IF clause is present and false,
2973or the value of the NUM_THREADS clause, if present, or 0.
2974
2975   The function needs to create the appropriate number of threads and/or
2976launch them from the dock.  It needs to create the team structure and
2977assign team ids.
2978
2979       void GOMP_parallel_end (void)
2980
2981   Tears down the team and returns us to the previous
2982'omp_in_parallel()' state.
2983
2984
2985File: libgomp.info,  Node: Implementing FOR construct,  Next: Implementing ORDERED construct,  Prev: Implementing PARALLEL construct,  Up: The libgomp ABI
2986
29879.11 Implementing FOR construct
2988===============================
2989
2990       #pragma omp parallel for
2991       for (i = lb; i <= ub; i++)
2992         body;
2993
2994   becomes
2995
2996       void subfunction (void *data)
2997       {
2998         long _s0, _e0;
2999         while (GOMP_loop_static_next (&_s0, &_e0))
3000         {
3001           long _e1 = _e0, i;
3002           for (i = _s0; i < _e1; i++)
3003             body;
3004         }
3005         GOMP_loop_end_nowait ();
3006       }
3007
3008       GOMP_parallel_loop_static (subfunction, NULL, 0, lb, ub+1, 1, 0);
3009       subfunction (NULL);
3010       GOMP_parallel_end ();
3011
3012       #pragma omp for schedule(runtime)
3013       for (i = 0; i < n; i++)
3014         body;
3015
3016   becomes
3017
3018       {
3019         long i, _s0, _e0;
3020         if (GOMP_loop_runtime_start (0, n, 1, &_s0, &_e0))
3021           do {
3022             long _e1 = _e0;
3023             for (i = _s0, i < _e0; i++)
3024               body;
3025           } while (GOMP_loop_runtime_next (&_s0, _&e0));
3026         GOMP_loop_end ();
3027       }
3028
3029   Note that while it looks like there is trickiness to propagating a
3030non-constant STEP, there isn't really.  We're explicitly allowed to
3031evaluate it as many times as we want, and any variables involved should
3032automatically be handled as PRIVATE or SHARED like any other variables.
3033So the expression should remain evaluable in the subfunction.  We can
3034also pull it into a local variable if we like, but since its supposed to
3035remain unchanged, we can also not if we like.
3036
3037   If we have SCHEDULE(STATIC), and no ORDERED, then we ought to be able
3038to get away with no work-sharing context at all, since we can simply
3039perform the arithmetic directly in each thread to divide up the
3040iterations.  Which would mean that we wouldn't need to call any of these
3041routines.
3042
3043   There are separate routines for handling loops with an ORDERED
3044clause.  Bookkeeping for that is non-trivial...
3045
3046
3047File: libgomp.info,  Node: Implementing ORDERED construct,  Next: Implementing SECTIONS construct,  Prev: Implementing FOR construct,  Up: The libgomp ABI
3048
30499.12 Implementing ORDERED construct
3050===================================
3051
3052       void GOMP_ordered_start (void)
3053       void GOMP_ordered_end (void)
3054
3055
3056File: libgomp.info,  Node: Implementing SECTIONS construct,  Next: Implementing SINGLE construct,  Prev: Implementing ORDERED construct,  Up: The libgomp ABI
3057
30589.13 Implementing SECTIONS construct
3059====================================
3060
3061A block as
3062
3063       #pragma omp sections
3064       {
3065         #pragma omp section
3066         stmt1;
3067         #pragma omp section
3068         stmt2;
3069         #pragma omp section
3070         stmt3;
3071       }
3072
3073   becomes
3074
3075       for (i = GOMP_sections_start (3); i != 0; i = GOMP_sections_next ())
3076         switch (i)
3077           {
3078           case 1:
3079             stmt1;
3080             break;
3081           case 2:
3082             stmt2;
3083             break;
3084           case 3:
3085             stmt3;
3086             break;
3087           }
3088       GOMP_barrier ();
3089
3090
3091File: libgomp.info,  Node: Implementing SINGLE construct,  Next: Implementing OpenACC's PARALLEL construct,  Prev: Implementing SECTIONS construct,  Up: The libgomp ABI
3092
30939.14 Implementing SINGLE construct
3094==================================
3095
3096A block like
3097
3098       #pragma omp single
3099       {
3100         body;
3101       }
3102
3103   becomes
3104
3105       if (GOMP_single_start ())
3106         body;
3107       GOMP_barrier ();
3108
3109   while
3110
3111       #pragma omp single copyprivate(x)
3112         body;
3113
3114   becomes
3115
3116       datap = GOMP_single_copy_start ();
3117       if (datap == NULL)
3118         {
3119           body;
3120           data.x = x;
3121           GOMP_single_copy_end (&data);
3122         }
3123       else
3124         x = datap->x;
3125       GOMP_barrier ();
3126
3127
3128File: libgomp.info,  Node: Implementing OpenACC's PARALLEL construct,  Prev: Implementing SINGLE construct,  Up: The libgomp ABI
3129
31309.15 Implementing OpenACC's PARALLEL construct
3131==============================================
3132
3133       void GOACC_parallel ()
3134
3135
3136File: libgomp.info,  Node: Reporting Bugs,  Next: Copying,  Prev: The libgomp ABI,  Up: Top
3137
313810 Reporting Bugs
3139*****************
3140
3141Bugs in the GNU Offloading and Multi Processing Runtime Library should
3142be reported via Bugzilla (http://gcc.gnu.org/bugzilla/).  Please add
3143"openacc", or "openmp", or both to the keywords field in the bug report,
3144as appropriate.
3145
3146
3147File: libgomp.info,  Node: Copying,  Next: GNU Free Documentation License,  Prev: Reporting Bugs,  Up: Top
3148
3149GNU General Public License
3150**************************
3151
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3623     License.
3624
3625     An "entity transaction" is a transaction transferring control of an
3626     organization, or substantially all assets of one, or subdividing an
3627     organization, or merging organizations.  If propagation of a
3628     covered work results from an entity transaction, each party to that
3629     transaction who receives a copy of the work also receives whatever
3630     licenses to the work the party's predecessor in interest had or
3631     could give under the previous paragraph, plus a right to possession
3632     of the Corresponding Source of the work from the predecessor in
3633     interest, if the predecessor has it or can get it with reasonable
3634     efforts.
3635
3636     You may not impose any further restrictions on the exercise of the
3637     rights granted or affirmed under this License.  For example, you
3638     may not impose a license fee, royalty, or other charge for exercise
3639     of rights granted under this License, and you may not initiate
3640     litigation (including a cross-claim or counterclaim in a lawsuit)
3641     alleging that any patent claim is infringed by making, using,
3642     selling, offering for sale, or importing the Program or any portion
3643     of it.
3644
3645  11. Patents.
3646
3647     A "contributor" is a copyright holder who authorizes use under this
3648     License of the Program or a work on which the Program is based.
3649     The work thus licensed is called the contributor's "contributor
3650     version".
3651
3652     A contributor's "essential patent claims" are all patent claims
3653     owned or controlled by the contributor, whether already acquired or
3654     hereafter acquired, that would be infringed by some manner,
3655     permitted by this License, of making, using, or selling its
3656     contributor version, but do not include claims that would be
3657     infringed only as a consequence of further modification of the
3658     contributor version.  For purposes of this definition, "control"
3659     includes the right to grant patent sublicenses in a manner
3660     consistent with the requirements of this License.
3661
3662     Each contributor grants you a non-exclusive, worldwide,
3663     royalty-free patent license under the contributor's essential
3664     patent claims, to make, use, sell, offer for sale, import and
3665     otherwise run, modify and propagate the contents of its contributor
3666     version.
3667
3668     In the following three paragraphs, a "patent license" is any
3669     express agreement or commitment, however denominated, not to
3670     enforce a patent (such as an express permission to practice a
3671     patent or covenant not to sue for patent infringement).  To "grant"
3672     such a patent license to a party means to make such an agreement or
3673     commitment not to enforce a patent against the party.
3674
3675     If you convey a covered work, knowingly relying on a patent
3676     license, and the Corresponding Source of the work is not available
3677     for anyone to copy, free of charge and under the terms of this
3678     License, through a publicly available network server or other
3679     readily accessible means, then you must either (1) cause the
3680     Corresponding Source to be so available, or (2) arrange to deprive
3681     yourself of the benefit of the patent license for this particular
3682     work, or (3) arrange, in a manner consistent with the requirements
3683     of this License, to extend the patent license to downstream
3684     recipients.  "Knowingly relying" means you have actual knowledge
3685     that, but for the patent license, your conveying the covered work
3686     in a country, or your recipient's use of the covered work in a
3687     country, would infringe one or more identifiable patents in that
3688     country that you have reason to believe are valid.
3689
3690     If, pursuant to or in connection with a single transaction or
3691     arrangement, you convey, or propagate by procuring conveyance of, a
3692     covered work, and grant a patent license to some of the parties
3693     receiving the covered work authorizing them to use, propagate,
3694     modify or convey a specific copy of the covered work, then the
3695     patent license you grant is automatically extended to all
3696     recipients of the covered work and works based on it.
3697
3698     A patent license is "discriminatory" if it does not include within
3699     the scope of its coverage, prohibits the exercise of, or is
3700     conditioned on the non-exercise of one or more of the rights that
3701     are specifically granted under this License.  You may not convey a
3702     covered work if you are a party to an arrangement with a third
3703     party that is in the business of distributing software, under which
3704     you make payment to the third party based on the extent of your
3705     activity of conveying the work, and under which the third party
3706     grants, to any of the parties who would receive the covered work
3707     from you, a discriminatory patent license (a) in connection with
3708     copies of the covered work conveyed by you (or copies made from
3709     those copies), or (b) primarily for and in connection with specific
3710     products or compilations that contain the covered work, unless you
3711     entered into that arrangement, or that patent license was granted,
3712     prior to 28 March 2007.
3713
3714     Nothing in this License shall be construed as excluding or limiting
3715     any implied license or other defenses to infringement that may
3716     otherwise be available to you under applicable patent law.
3717
3718  12. No Surrender of Others' Freedom.
3719
3720     If conditions are imposed on you (whether by court order, agreement
3721     or otherwise) that contradict the conditions of this License, they
3722     do not excuse you from the conditions of this License.  If you
3723     cannot convey a covered work so as to satisfy simultaneously your
3724     obligations under this License and any other pertinent obligations,
3725     then as a consequence you may not convey it at all.  For example,
3726     if you agree to terms that obligate you to collect a royalty for
3727     further conveying from those to whom you convey the Program, the
3728     only way you could satisfy both those terms and this License would
3729     be to refrain entirely from conveying the Program.
3730
3731  13. Use with the GNU Affero General Public License.
3732
3733     Notwithstanding any other provision of this License, you have
3734     permission to link or combine any covered work with a work licensed
3735     under version 3 of the GNU Affero General Public License into a
3736     single combined work, and to convey the resulting work.  The terms
3737     of this License will continue to apply to the part which is the
3738     covered work, but the special requirements of the GNU Affero
3739     General Public License, section 13, concerning interaction through
3740     a network will apply to the combination as such.
3741
3742  14. Revised Versions of this License.
3743
3744     The Free Software Foundation may publish revised and/or new
3745     versions of the GNU General Public License from time to time.  Such
3746     new versions will be similar in spirit to the present version, but
3747     may differ in detail to address new problems or concerns.
3748
3749     Each version is given a distinguishing version number.  If the
3750     Program specifies that a certain numbered version of the GNU
3751     General Public License "or any later version" applies to it, you
3752     have the option of following the terms and conditions either of
3753     that numbered version or of any later version published by the Free
3754     Software Foundation.  If the Program does not specify a version
3755     number of the GNU General Public License, you may choose any
3756     version ever published by the Free Software Foundation.
3757
3758     If the Program specifies that a proxy can decide which future
3759     versions of the GNU General Public License can be used, that
3760     proxy's public statement of acceptance of a version permanently
3761     authorizes you to choose that version for the Program.
3762
3763     Later license versions may give you additional or different
3764     permissions.  However, no additional obligations are imposed on any
3765     author or copyright holder as a result of your choosing to follow a
3766     later version.
3767
3768  15. Disclaimer of Warranty.
3769
3770     THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
3771     APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
3772     COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
3773     WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
3774     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
3775     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
3776     RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.
3777     SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
3778     NECESSARY SERVICING, REPAIR OR CORRECTION.
3779
3780  16. Limitation of Liability.
3781
3782     IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
3783     WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES
3784     AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
3785     DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
3786     CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
3787     THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
3788     BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
3789     PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
3790     PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF
3791     THE POSSIBILITY OF SUCH DAMAGES.
3792
3793  17. Interpretation of Sections 15 and 16.
3794
3795     If the disclaimer of warranty and limitation of liability provided
3796     above cannot be given local legal effect according to their terms,
3797     reviewing courts shall apply local law that most closely
3798     approximates an absolute waiver of all civil liability in
3799     connection with the Program, unless a warranty or assumption of
3800     liability accompanies a copy of the Program in return for a fee.
3801
3802END OF TERMS AND CONDITIONS
3803===========================
3804
3805How to Apply These Terms to Your New Programs
3806=============================================
3807
3808If you develop a new program, and you want it to be of the greatest
3809possible use to the public, the best way to achieve this is to make it
3810free software which everyone can redistribute and change under these
3811terms.
3812
3813   To do so, attach the following notices to the program.  It is safest
3814to attach them to the start of each source file to most effectively
3815state the exclusion of warranty; and each file should have at least the
3816"copyright" line and a pointer to where the full notice is found.
3817
3818     ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
3819     Copyright (C) YEAR NAME OF AUTHOR
3820
3821     This program is free software: you can redistribute it and/or modify
3822     it under the terms of the GNU General Public License as published by
3823     the Free Software Foundation, either version 3 of the License, or (at
3824     your option) any later version.
3825
3826     This program is distributed in the hope that it will be useful, but
3827     WITHOUT ANY WARRANTY; without even the implied warranty of
3828     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
3829     General Public License for more details.
3830
3831     You should have received a copy of the GNU General Public License
3832     along with this program.  If not, see <http://www.gnu.org/licenses/>.
3833
3834   Also add information on how to contact you by electronic and paper
3835mail.
3836
3837   If the program does terminal interaction, make it output a short
3838notice like this when it starts in an interactive mode:
3839
3840     PROGRAM Copyright (C) YEAR NAME OF AUTHOR
3841     This program comes with ABSOLUTELY NO WARRANTY; for details type 'show w'.
3842     This is free software, and you are welcome to redistribute it
3843     under certain conditions; type 'show c' for details.
3844
3845   The hypothetical commands 'show w' and 'show c' should show the
3846appropriate parts of the General Public License.  Of course, your
3847program's commands might be different; for a GUI interface, you would
3848use an "about box".
3849
3850   You should also get your employer (if you work as a programmer) or
3851school, if any, to sign a "copyright disclaimer" for the program, if
3852necessary.  For more information on this, and how to apply and follow
3853the GNU GPL, see <http://www.gnu.org/licenses/>.
3854
3855   The GNU General Public License does not permit incorporating your
3856program into proprietary programs.  If your program is a subroutine
3857library, you may consider it more useful to permit linking proprietary
3858applications with the library.  If this is what you want to do, use the
3859GNU Lesser General Public License instead of this License.  But first,
3860please read <http://www.gnu.org/philosophy/why-not-lgpl.html>.
3861
3862
3863File: libgomp.info,  Node: GNU Free Documentation License,  Next: Funding,  Prev: Copying,  Up: Top
3864
3865GNU Free Documentation License
3866******************************
3867
3868                     Version 1.3, 3 November 2008
3869
3870     Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
3871     <http://fsf.org/>
3872
3873     Everyone is permitted to copy and distribute verbatim copies
3874     of this license document, but changing it is not allowed.
3875
3876  0. PREAMBLE
3877
3878     The purpose of this License is to make a manual, textbook, or other
3879     functional and useful document "free" in the sense of freedom: to
3880     assure everyone the effective freedom to copy and redistribute it,
3881     with or without modifying it, either commercially or
3882     noncommercially.  Secondarily, this License preserves for the
3883     author and publisher a way to get credit for their work, while not
3884     being considered responsible for modifications made by others.
3885
3886     This License is a kind of "copyleft", which means that derivative
3887     works of the document must themselves be free in the same sense.
3888     It complements the GNU General Public License, which is a copyleft
3889     license designed for free software.
3890
3891     We have designed this License in order to use it for manuals for
3892     free software, because free software needs free documentation: a
3893     free program should come with manuals providing the same freedoms
3894     that the software does.  But this License is not limited to
3895     software manuals; it can be used for any textual work, regardless
3896     of subject matter or whether it is published as a printed book.  We
3897     recommend this License principally for works whose purpose is
3898     instruction or reference.
3899
3900  1. APPLICABILITY AND DEFINITIONS
3901
3902     This License applies to any manual or other work, in any medium,
3903     that contains a notice placed by the copyright holder saying it can
3904     be distributed under the terms of this License.  Such a notice
3905     grants a world-wide, royalty-free license, unlimited in duration,
3906     to use that work under the conditions stated herein.  The
3907     "Document", below, refers to any such manual or work.  Any member
3908     of the public is a licensee, and is addressed as "you".  You accept
3909     the license if you copy, modify or distribute the work in a way
3910     requiring permission under copyright law.
3911
3912     A "Modified Version" of the Document means any work containing the
3913     Document or a portion of it, either copied verbatim, or with
3914     modifications and/or translated into another language.
3915
3916     A "Secondary Section" is a named appendix or a front-matter section
3917     of the Document that deals exclusively with the relationship of the
3918     publishers or authors of the Document to the Document's overall
3919     subject (or to related matters) and contains nothing that could
3920     fall directly within that overall subject.  (Thus, if the Document
3921     is in part a textbook of mathematics, a Secondary Section may not
3922     explain any mathematics.)  The relationship could be a matter of
3923     historical connection with the subject or with related matters, or
3924     of legal, commercial, philosophical, ethical or political position
3925     regarding them.
3926
3927     The "Invariant Sections" are certain Secondary Sections whose
3928     titles are designated, as being those of Invariant Sections, in the
3929     notice that says that the Document is released under this License.
3930     If a section does not fit the above definition of Secondary then it
3931     is not allowed to be designated as Invariant.  The Document may
3932     contain zero Invariant Sections.  If the Document does not identify
3933     any Invariant Sections then there are none.
3934
3935     The "Cover Texts" are certain short passages of text that are
3936     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
3937     that says that the Document is released under this License.  A
3938     Front-Cover Text may be at most 5 words, and a Back-Cover Text may
3939     be at most 25 words.
3940
3941     A "Transparent" copy of the Document means a machine-readable copy,
3942     represented in a format whose specification is available to the
3943     general public, that is suitable for revising the document
3944     straightforwardly with generic text editors or (for images composed
3945     of pixels) generic paint programs or (for drawings) some widely
3946     available drawing editor, and that is suitable for input to text
3947     formatters or for automatic translation to a variety of formats
3948     suitable for input to text formatters.  A copy made in an otherwise
3949     Transparent file format whose markup, or absence of markup, has
3950     been arranged to thwart or discourage subsequent modification by
3951     readers is not Transparent.  An image format is not Transparent if
3952     used for any substantial amount of text.  A copy that is not
3953     "Transparent" is called "Opaque".
3954
3955     Examples of suitable formats for Transparent copies include plain
3956     ASCII without markup, Texinfo input format, LaTeX input format,
3957     SGML or XML using a publicly available DTD, and standard-conforming
3958     simple HTML, PostScript or PDF designed for human modification.
3959     Examples of transparent image formats include PNG, XCF and JPG.
3960     Opaque formats include proprietary formats that can be read and
3961     edited only by proprietary word processors, SGML or XML for which
3962     the DTD and/or processing tools are not generally available, and
3963     the machine-generated HTML, PostScript or PDF produced by some word
3964     processors for output purposes only.
3965
3966     The "Title Page" means, for a printed book, the title page itself,
3967     plus such following pages as are needed to hold, legibly, the
3968     material this License requires to appear in the title page.  For
3969     works in formats which do not have any title page as such, "Title
3970     Page" means the text near the most prominent appearance of the
3971     work's title, preceding the beginning of the body of the text.
3972
3973     The "publisher" means any person or entity that distributes copies
3974     of the Document to the public.
3975
3976     A section "Entitled XYZ" means a named subunit of the Document
3977     whose title either is precisely XYZ or contains XYZ in parentheses
3978     following text that translates XYZ in another language.  (Here XYZ
3979     stands for a specific section name mentioned below, such as
3980     "Acknowledgements", "Dedications", "Endorsements", or "History".)
3981     To "Preserve the Title" of such a section when you modify the
3982     Document means that it remains a section "Entitled XYZ" according
3983     to this definition.
3984
3985     The Document may include Warranty Disclaimers next to the notice
3986     which states that this License applies to the Document.  These
3987     Warranty Disclaimers are considered to be included by reference in
3988     this License, but only as regards disclaiming warranties: any other
3989     implication that these Warranty Disclaimers may have is void and
3990     has no effect on the meaning of this License.
3991
3992  2. VERBATIM COPYING
3993
3994     You may copy and distribute the Document in any medium, either
3995     commercially or noncommercially, provided that this License, the
3996     copyright notices, and the license notice saying this License
3997     applies to the Document are reproduced in all copies, and that you
3998     add no other conditions whatsoever to those of this License.  You
3999     may not use technical measures to obstruct or control the reading
4000     or further copying of the copies you make or distribute.  However,
4001     you may accept compensation in exchange for copies.  If you
4002     distribute a large enough number of copies you must also follow the
4003     conditions in section 3.
4004
4005     You may also lend copies, under the same conditions stated above,
4006     and you may publicly display copies.
4007
4008  3. COPYING IN QUANTITY
4009
4010     If you publish printed copies (or copies in media that commonly
4011     have printed covers) of the Document, numbering more than 100, and
4012     the Document's license notice requires Cover Texts, you must
4013     enclose the copies in covers that carry, clearly and legibly, all
4014     these Cover Texts: Front-Cover Texts on the front cover, and
4015     Back-Cover Texts on the back cover.  Both covers must also clearly
4016     and legibly identify you as the publisher of these copies.  The
4017     front cover must present the full title with all words of the title
4018     equally prominent and visible.  You may add other material on the
4019     covers in addition.  Copying with changes limited to the covers, as
4020     long as they preserve the title of the Document and satisfy these
4021     conditions, can be treated as verbatim copying in other respects.
4022
4023     If the required texts for either cover are too voluminous to fit
4024     legibly, you should put the first ones listed (as many as fit
4025     reasonably) on the actual cover, and continue the rest onto
4026     adjacent pages.
4027
4028     If you publish or distribute Opaque copies of the Document
4029     numbering more than 100, you must either include a machine-readable
4030     Transparent copy along with each Opaque copy, or state in or with
4031     each Opaque copy a computer-network location from which the general
4032     network-using public has access to download using public-standard
4033     network protocols a complete Transparent copy of the Document, free
4034     of added material.  If you use the latter option, you must take
4035     reasonably prudent steps, when you begin distribution of Opaque
4036     copies in quantity, to ensure that this Transparent copy will
4037     remain thus accessible at the stated location until at least one
4038     year after the last time you distribute an Opaque copy (directly or
4039     through your agents or retailers) of that edition to the public.
4040
4041     It is requested, but not required, that you contact the authors of
4042     the Document well before redistributing any large number of copies,
4043     to give them a chance to provide you with an updated version of the
4044     Document.
4045
4046  4. MODIFICATIONS
4047
4048     You may copy and distribute a Modified Version of the Document
4049     under the conditions of sections 2 and 3 above, provided that you
4050     release the Modified Version under precisely this License, with the
4051     Modified Version filling the role of the Document, thus licensing
4052     distribution and modification of the Modified Version to whoever
4053     possesses a copy of it.  In addition, you must do these things in
4054     the Modified Version:
4055
4056       A. Use in the Title Page (and on the covers, if any) a title
4057          distinct from that of the Document, and from those of previous
4058          versions (which should, if there were any, be listed in the
4059          History section of the Document).  You may use the same title
4060          as a previous version if the original publisher of that
4061          version gives permission.
4062
4063       B. List on the Title Page, as authors, one or more persons or
4064          entities responsible for authorship of the modifications in
4065          the Modified Version, together with at least five of the
4066          principal authors of the Document (all of its principal
4067          authors, if it has fewer than five), unless they release you
4068          from this requirement.
4069
4070       C. State on the Title page the name of the publisher of the
4071          Modified Version, as the publisher.
4072
4073       D. Preserve all the copyright notices of the Document.
4074
4075       E. Add an appropriate copyright notice for your modifications
4076          adjacent to the other copyright notices.
4077
4078       F. Include, immediately after the copyright notices, a license
4079          notice giving the public permission to use the Modified
4080          Version under the terms of this License, in the form shown in
4081          the Addendum below.
4082
4083       G. Preserve in that license notice the full lists of Invariant
4084          Sections and required Cover Texts given in the Document's
4085          license notice.
4086
4087       H. Include an unaltered copy of this License.
4088
4089       I. Preserve the section Entitled "History", Preserve its Title,
4090          and add to it an item stating at least the title, year, new
4091          authors, and publisher of the Modified Version as given on the
4092          Title Page.  If there is no section Entitled "History" in the
4093          Document, create one stating the title, year, authors, and
4094          publisher of the Document as given on its Title Page, then add
4095          an item describing the Modified Version as stated in the
4096          previous sentence.
4097
4098       J. Preserve the network location, if any, given in the Document
4099          for public access to a Transparent copy of the Document, and
4100          likewise the network locations given in the Document for
4101          previous versions it was based on.  These may be placed in the
4102          "History" section.  You may omit a network location for a work
4103          that was published at least four years before the Document
4104          itself, or if the original publisher of the version it refers
4105          to gives permission.
4106
4107       K. For any section Entitled "Acknowledgements" or "Dedications",
4108          Preserve the Title of the section, and preserve in the section
4109          all the substance and tone of each of the contributor
4110          acknowledgements and/or dedications given therein.
4111
4112       L. Preserve all the Invariant Sections of the Document, unaltered
4113          in their text and in their titles.  Section numbers or the
4114          equivalent are not considered part of the section titles.
4115
4116       M. Delete any section Entitled "Endorsements".  Such a section
4117          may not be included in the Modified Version.
4118
4119       N. Do not retitle any existing section to be Entitled
4120          "Endorsements" or to conflict in title with any Invariant
4121          Section.
4122
4123       O. Preserve any Warranty Disclaimers.
4124
4125     If the Modified Version includes new front-matter sections or
4126     appendices that qualify as Secondary Sections and contain no
4127     material copied from the Document, you may at your option designate
4128     some or all of these sections as invariant.  To do this, add their
4129     titles to the list of Invariant Sections in the Modified Version's
4130     license notice.  These titles must be distinct from any other
4131     section titles.
4132
4133     You may add a section Entitled "Endorsements", provided it contains
4134     nothing but endorsements of your Modified Version by various
4135     parties--for example, statements of peer review or that the text
4136     has been approved by an organization as the authoritative
4137     definition of a standard.
4138
4139     You may add a passage of up to five words as a Front-Cover Text,
4140     and a passage of up to 25 words as a Back-Cover Text, to the end of
4141     the list of Cover Texts in the Modified Version.  Only one passage
4142     of Front-Cover Text and one of Back-Cover Text may be added by (or
4143     through arrangements made by) any one entity.  If the Document
4144     already includes a cover text for the same cover, previously added
4145     by you or by arrangement made by the same entity you are acting on
4146     behalf of, you may not add another; but you may replace the old
4147     one, on explicit permission from the previous publisher that added
4148     the old one.
4149
4150     The author(s) and publisher(s) of the Document do not by this
4151     License give permission to use their names for publicity for or to
4152     assert or imply endorsement of any Modified Version.
4153
4154  5. COMBINING DOCUMENTS
4155
4156     You may combine the Document with other documents released under
4157     this License, under the terms defined in section 4 above for
4158     modified versions, provided that you include in the combination all
4159     of the Invariant Sections of all of the original documents,
4160     unmodified, and list them all as Invariant Sections of your
4161     combined work in its license notice, and that you preserve all
4162     their Warranty Disclaimers.
4163
4164     The combined work need only contain one copy of this License, and
4165     multiple identical Invariant Sections may be replaced with a single
4166     copy.  If there are multiple Invariant Sections with the same name
4167     but different contents, make the title of each such section unique
4168     by adding at the end of it, in parentheses, the name of the
4169     original author or publisher of that section if known, or else a
4170     unique number.  Make the same adjustment to the section titles in
4171     the list of Invariant Sections in the license notice of the
4172     combined work.
4173
4174     In the combination, you must combine any sections Entitled
4175     "History" in the various original documents, forming one section
4176     Entitled "History"; likewise combine any sections Entitled
4177     "Acknowledgements", and any sections Entitled "Dedications".  You
4178     must delete all sections Entitled "Endorsements."
4179
4180  6. COLLECTIONS OF DOCUMENTS
4181
4182     You may make a collection consisting of the Document and other
4183     documents released under this License, and replace the individual
4184     copies of this License in the various documents with a single copy
4185     that is included in the collection, provided that you follow the
4186     rules of this License for verbatim copying of each of the documents
4187     in all other respects.
4188
4189     You may extract a single document from such a collection, and
4190     distribute it individually under this License, provided you insert
4191     a copy of this License into the extracted document, and follow this
4192     License in all other respects regarding verbatim copying of that
4193     document.
4194
4195  7. AGGREGATION WITH INDEPENDENT WORKS
4196
4197     A compilation of the Document or its derivatives with other
4198     separate and independent documents or works, in or on a volume of a
4199     storage or distribution medium, is called an "aggregate" if the
4200     copyright resulting from the compilation is not used to limit the
4201     legal rights of the compilation's users beyond what the individual
4202     works permit.  When the Document is included in an aggregate, this
4203     License does not apply to the other works in the aggregate which
4204     are not themselves derivative works of the Document.
4205
4206     If the Cover Text requirement of section 3 is applicable to these
4207     copies of the Document, then if the Document is less than one half
4208     of the entire aggregate, the Document's Cover Texts may be placed
4209     on covers that bracket the Document within the aggregate, or the
4210     electronic equivalent of covers if the Document is in electronic
4211     form.  Otherwise they must appear on printed covers that bracket
4212     the whole aggregate.
4213
4214  8. TRANSLATION
4215
4216     Translation is considered a kind of modification, so you may
4217     distribute translations of the Document under the terms of section
4218     4.  Replacing Invariant Sections with translations requires special
4219     permission from their copyright holders, but you may include
4220     translations of some or all Invariant Sections in addition to the
4221     original versions of these Invariant Sections.  You may include a
4222     translation of this License, and all the license notices in the
4223     Document, and any Warranty Disclaimers, provided that you also
4224     include the original English version of this License and the
4225     original versions of those notices and disclaimers.  In case of a
4226     disagreement between the translation and the original version of
4227     this License or a notice or disclaimer, the original version will
4228     prevail.
4229
4230     If a section in the Document is Entitled "Acknowledgements",
4231     "Dedications", or "History", the requirement (section 4) to
4232     Preserve its Title (section 1) will typically require changing the
4233     actual title.
4234
4235  9. TERMINATION
4236
4237     You may not copy, modify, sublicense, or distribute the Document
4238     except as expressly provided under this License.  Any attempt
4239     otherwise to copy, modify, sublicense, or distribute it is void,
4240     and will automatically terminate your rights under this License.
4241
4242     However, if you cease all violation of this License, then your
4243     license from a particular copyright holder is reinstated (a)
4244     provisionally, unless and until the copyright holder explicitly and
4245     finally terminates your license, and (b) permanently, if the
4246     copyright holder fails to notify you of the violation by some
4247     reasonable means prior to 60 days after the cessation.
4248
4249     Moreover, your license from a particular copyright holder is
4250     reinstated permanently if the copyright holder notifies you of the
4251     violation by some reasonable means, this is the first time you have
4252     received notice of violation of this License (for any work) from
4253     that copyright holder, and you cure the violation prior to 30 days
4254     after your receipt of the notice.
4255
4256     Termination of your rights under this section does not terminate
4257     the licenses of parties who have received copies or rights from you
4258     under this License.  If your rights have been terminated and not
4259     permanently reinstated, receipt of a copy of some or all of the
4260     same material does not give you any rights to use it.
4261
4262  10. FUTURE REVISIONS OF THIS LICENSE
4263
4264     The Free Software Foundation may publish new, revised versions of
4265     the GNU Free Documentation License from time to time.  Such new
4266     versions will be similar in spirit to the present version, but may
4267     differ in detail to address new problems or concerns.  See
4268     <http://www.gnu.org/copyleft/>.
4269
4270     Each version of the License is given a distinguishing version
4271     number.  If the Document specifies that a particular numbered
4272     version of this License "or any later version" applies to it, you
4273     have the option of following the terms and conditions either of
4274     that specified version or of any later version that has been
4275     published (not as a draft) by the Free Software Foundation.  If the
4276     Document does not specify a version number of this License, you may
4277     choose any version ever published (not as a draft) by the Free
4278     Software Foundation.  If the Document specifies that a proxy can
4279     decide which future versions of this License can be used, that
4280     proxy's public statement of acceptance of a version permanently
4281     authorizes you to choose that version for the Document.
4282
4283  11. RELICENSING
4284
4285     "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
4286     World Wide Web server that publishes copyrightable works and also
4287     provides prominent facilities for anybody to edit those works.  A
4288     public wiki that anybody can edit is an example of such a server.
4289     A "Massive Multiauthor Collaboration" (or "MMC") contained in the
4290     site means any set of copyrightable works thus published on the MMC
4291     site.
4292
4293     "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
4294     license published by Creative Commons Corporation, a not-for-profit
4295     corporation with a principal place of business in San Francisco,
4296     California, as well as future copyleft versions of that license
4297     published by that same organization.
4298
4299     "Incorporate" means to publish or republish a Document, in whole or
4300     in part, as part of another Document.
4301
4302     An MMC is "eligible for relicensing" if it is licensed under this
4303     License, and if all works that were first published under this
4304     License somewhere other than this MMC, and subsequently
4305     incorporated in whole or in part into the MMC, (1) had no cover
4306     texts or invariant sections, and (2) were thus incorporated prior
4307     to November 1, 2008.
4308
4309     The operator of an MMC Site may republish an MMC contained in the
4310     site under CC-BY-SA on the same site at any time before August 1,
4311     2009, provided the MMC is eligible for relicensing.
4312
4313ADDENDUM: How to use this License for your documents
4314====================================================
4315
4316To use this License in a document you have written, include a copy of
4317the License in the document and put the following copyright and license
4318notices just after the title page:
4319
4320       Copyright (C)  YEAR  YOUR NAME.
4321       Permission is granted to copy, distribute and/or modify this document
4322       under the terms of the GNU Free Documentation License, Version 1.3
4323       or any later version published by the Free Software Foundation;
4324       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
4325       Texts.  A copy of the license is included in the section entitled ``GNU
4326       Free Documentation License''.
4327
4328   If you have Invariant Sections, Front-Cover Texts and Back-Cover
4329Texts, replace the "with...Texts."  line with this:
4330
4331         with the Invariant Sections being LIST THEIR TITLES, with
4332         the Front-Cover Texts being LIST, and with the Back-Cover Texts
4333         being LIST.
4334
4335   If you have Invariant Sections without Cover Texts, or some other
4336combination of the three, merge those two alternatives to suit the
4337situation.
4338
4339   If your document contains nontrivial examples of program code, we
4340recommend releasing these examples in parallel under your choice of free
4341software license, such as the GNU General Public License, to permit
4342their use in free software.
4343
4344
4345File: libgomp.info,  Node: Funding,  Next: Library Index,  Prev: GNU Free Documentation License,  Up: Top
4346
4347Funding Free Software
4348*********************
4349
4350If you want to have more free software a few years from now, it makes
4351sense for you to help encourage people to contribute funds for its
4352development.  The most effective approach known is to encourage
4353commercial redistributors to donate.
4354
4355   Users of free software systems can boost the pace of development by
4356encouraging for-a-fee distributors to donate part of their selling price
4357to free software developers--the Free Software Foundation, and others.
4358
4359   The way to convince distributors to do this is to demand it and
4360expect it from them.  So when you compare distributors, judge them
4361partly by how much they give to free software development.  Show
4362distributors they must compete to be the one who gives the most.
4363
4364   To make this approach work, you must insist on numbers that you can
4365compare, such as, "We will donate ten dollars to the Frobnitz project
4366for each disk sold."  Don't be satisfied with a vague promise, such as
4367"A portion of the profits are donated," since it doesn't give a basis
4368for comparison.
4369
4370   Even a precise fraction "of the profits from this disk" is not very
4371meaningful, since creative accounting and unrelated business decisions
4372can greatly alter what fraction of the sales price counts as profit.  If
4373the price you pay is $50, ten percent of the profit is probably less
4374than a dollar; it might be a few cents, or nothing at all.
4375
4376   Some redistributors do development work themselves.  This is useful
4377too; but to keep everyone honest, you need to inquire how much they do,
4378and what kind.  Some kinds of development make much more long-term
4379difference than others.  For example, maintaining a separate version of
4380a program contributes very little; maintaining the standard version of a
4381program for the whole community contributes much.  Easy new ports
4382contribute little, since someone else would surely do them; difficult
4383ports such as adding a new CPU to the GNU Compiler Collection contribute
4384more; major new features or packages contribute the most.
4385
4386   By establishing the idea that supporting further development is "the
4387proper thing to do" when distributing free software for a fee, we can
4388assure a steady flow of resources into making more free software.
4389
4390     Copyright (C) 1994 Free Software Foundation, Inc.
4391     Verbatim copying and redistribution of this section is permitted
4392     without royalty; alteration is not permitted.
4393
4394
4395File: libgomp.info,  Node: Library Index,  Prev: Funding,  Up: Top
4396
4397Library Index
4398*************
4399
4400�[index�]
4401* Menu:
4402
4403* Environment Variable:                  OMP_CANCELLATION.      (line 6)
4404* Environment Variable <1>:              OMP_DISPLAY_ENV.       (line 6)
4405* Environment Variable <2>:              OMP_DEFAULT_DEVICE.    (line 6)
4406* Environment Variable <3>:              OMP_DYNAMIC.           (line 6)
4407* Environment Variable <4>:              OMP_MAX_ACTIVE_LEVELS. (line 6)
4408* Environment Variable <5>:              OMP_MAX_TASK_PRIORITY. (line 6)
4409* Environment Variable <6>:              OMP_NESTED.            (line 6)
4410* Environment Variable <7>:              OMP_NUM_THREADS.       (line 6)
4411* Environment Variable <8>:              OMP_PROC_BIND.         (line 6)
4412* Environment Variable <9>:              OMP_PLACES.            (line 6)
4413* Environment Variable <10>:             OMP_STACKSIZE.         (line 6)
4414* Environment Variable <11>:             OMP_SCHEDULE.          (line 6)
4415* Environment Variable <12>:             OMP_THREAD_LIMIT.      (line 6)
4416* Environment Variable <13>:             OMP_WAIT_POLICY.       (line 6)
4417* Environment Variable <14>:             GOMP_CPU_AFFINITY.     (line 6)
4418* Environment Variable <15>:             GOMP_DEBUG.            (line 6)
4419* Environment Variable <16>:             GOMP_STACKSIZE.        (line 6)
4420* Environment Variable <17>:             GOMP_SPINCOUNT.        (line 6)
4421* Environment Variable <18>:             GOMP_RTEMS_THREAD_POOLS.
4422                                                                (line 6)
4423* FDL, GNU Free Documentation License:   GNU Free Documentation License.
4424                                                                (line 6)
4425* Implementation specific setting:       OMP_NESTED.            (line 6)
4426* Implementation specific setting <1>:   OMP_NUM_THREADS.       (line 6)
4427* Implementation specific setting <2>:   OMP_SCHEDULE.          (line 6)
4428* Implementation specific setting <3>:   GOMP_STACKSIZE.        (line 6)
4429* Implementation specific setting <4>:   GOMP_SPINCOUNT.        (line 6)
4430* Implementation specific setting <5>:   GOMP_RTEMS_THREAD_POOLS.
4431                                                                (line 6)
4432* Introduction:                          Top.                   (line 6)
4433
4434
4435
4436Tag Table:
4437Node: Top2083
4438Node: Enabling OpenMP4489
4439Node: Runtime Library Routines5276
4440Node: omp_get_active_level8339
4441Node: omp_get_ancestor_thread_num9039
4442Node: omp_get_cancellation9969
4443Node: omp_get_default_device10783
4444Node: omp_get_dynamic11459
4445Node: omp_get_level12334
4446Node: omp_get_max_active_levels12954
4447Node: omp_get_max_task_priority13659
4448Node: omp_get_max_threads14279
4449Node: omp_get_nested15036
4450Node: omp_get_num_devices15950
4451Node: omp_get_num_procs16471
4452Node: omp_get_num_teams17010
4453Node: omp_get_num_threads17526
4454Node: omp_get_proc_bind18615
4455Node: omp_get_schedule19536
4456Node: omp_get_team_num20490
4457Node: omp_get_team_size20989
4458Node: omp_get_thread_limit21949
4459Node: omp_get_thread_num22568
4460Node: omp_in_parallel23439
4461Node: omp_in_final24088
4462Node: omp_is_initial_device24762
4463Node: omp_set_default_device25455
4464Node: omp_set_dynamic26246
4465Node: omp_set_max_active_levels27132
4466Node: omp_set_nested27909
4467Node: omp_set_num_threads28801
4468Node: omp_set_schedule29669
4469Node: omp_init_lock30750
4470Node: omp_set_lock31403
4471Node: omp_test_lock32258
4472Node: omp_unset_lock33234
4473Node: omp_destroy_lock34165
4474Node: omp_init_nest_lock34842
4475Node: omp_set_nest_lock35577
4476Node: omp_test_nest_lock36492
4477Node: omp_unset_nest_lock37519
4478Node: omp_destroy_nest_lock38534
4479Node: omp_get_wtick39285
4480Node: omp_get_wtime39877
4481Node: Environment Variables40653
4482Node: OMP_CANCELLATION42208
4483Node: OMP_DISPLAY_ENV42741
4484Node: OMP_DEFAULT_DEVICE43444
4485Node: OMP_DYNAMIC44224
4486Node: OMP_MAX_ACTIVE_LEVELS44820
4487Node: OMP_MAX_TASK_PRIORITY45470
4488Node: OMP_NESTED46128
4489Node: OMP_NUM_THREADS46733
4490Node: OMP_PROC_BIND47421
4491Node: OMP_PLACES48613
4492Node: OMP_STACKSIZE50790
4493Node: OMP_SCHEDULE51614
4494Node: OMP_THREAD_LIMIT52312
4495Node: OMP_WAIT_POLICY52912
4496Node: GOMP_CPU_AFFINITY53604
4497Node: GOMP_DEBUG55334
4498Node: GOMP_STACKSIZE55841
4499Node: GOMP_SPINCOUNT56670
4500Node: GOMP_RTEMS_THREAD_POOLS57874
4501Node: Enabling OpenACC60052
4502Node: OpenACC Runtime Library Routines61045
4503Node: acc_get_num_devices64839
4504Node: acc_set_device_type65565
4505Node: acc_get_device_type66329
4506Node: acc_set_device_num67044
4507Node: acc_get_device_num67828
4508Node: acc_async_test68625
4509Node: acc_async_test_all69617
4510Node: acc_wait70517
4511Node: acc_wait_all71379
4512Node: acc_wait_all_async72138
4513Node: acc_wait_async72890
4514Node: acc_init73597
4515Node: acc_shutdown74243
4516Node: acc_on_device74911
4517Node: acc_malloc75915
4518Node: acc_free76414
4519Node: acc_copyin76841
4520Node: acc_present_or_copyin77951
4521Node: acc_create79577
4522Node: acc_present_or_create80732
4523Node: acc_copyout82366
4524Node: acc_delete83389
4525Node: acc_update_device84364
4526Node: acc_update_self85476
4527Node: acc_map_data86580
4528Node: acc_unmap_data87265
4529Node: acc_deviceptr87786
4530Node: acc_hostptr88356
4531Node: acc_is_present88920
4532Node: acc_memcpy_to_device90447
4533Node: acc_memcpy_from_device91110
4534Node: acc_get_current_cuda_device91794
4535Node: acc_get_current_cuda_context92391
4536Node: acc_get_cuda_stream92985
4537Node: acc_set_cuda_stream93541
4538Node: OpenACC Environment Variables94073
4539Node: ACC_DEVICE_TYPE94532
4540Node: ACC_DEVICE_NUM94768
4541Node: GCC_ACC_NOTIFY95025
4542Node: CUDA Streams Usage95248
4543Ref: CUDA Streams Usage-Footnote-197148
4544Node: OpenACC Library Interoperability97257
4545Ref: OpenACC Library Interoperability-Footnote-1103613
4546Ref: OpenACC Library Interoperability-Footnote-2103865
4547Node: The libgomp ABI104073
4548Node: Implementing MASTER construct104929
4549Node: Implementing CRITICAL construct105343
4550Node: Implementing ATOMIC construct106082
4551Node: Implementing FLUSH construct106563
4552Node: Implementing BARRIER construct106834
4553Node: Implementing THREADPRIVATE construct107103
4554Node: Implementing PRIVATE clause107756
4555Node: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses108337
4556Node: Implementing REDUCTION clause109661
4557Node: Implementing PARALLEL construct110218
4558Node: Implementing FOR construct111475
4559Node: Implementing ORDERED construct113473
4560Node: Implementing SECTIONS construct113779
4561Node: Implementing SINGLE construct114545
4562Node: Implementing OpenACC's PARALLEL construct115257
4563Node: Reporting Bugs115515
4564Node: Copying115877
4565Node: GNU Free Documentation License153424
4566Node: Funding178547
4567Node: Library Index181073
4568
4569End Tag Table
4570
4571
4572Local Variables:
4573coding: utf-8
4574End:
4575