| \input texinfo @c -*-texinfo-*- |
| |
| @c %**start of header |
| @setfilename libgomp.info |
| @settitle GNU libgomp |
| @c %**end of header |
| |
| |
| @copying |
| Copyright @copyright{} 2006-2018 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Funding Free Software'', the Front-Cover |
| texts being (a) (see below), and with the Back-Cover Texts being (b) |
| (see below). A copy of the license is included in the section entitled |
| ``GNU Free Documentation License''. |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| You have freedom to copy and modify this GNU Manual, like GNU |
| software. Copies published by the Free Software Foundation raise |
| funds for GNU development. |
| @end copying |
| |
| @ifinfo |
| @dircategory GNU Libraries |
| @direntry |
| * libgomp: (libgomp). GNU Offloading and Multi Processing Runtime Library. |
| @end direntry |
| |
| This manual documents libgomp, the GNU Offloading and Multi Processing |
| Runtime library. This is the GNU implementation of the OpenMP and |
| OpenACC APIs for parallel and accelerator programming in C/C++ and |
| Fortran. |
| |
| Published by the Free Software Foundation |
| 51 Franklin Street, Fifth Floor |
| Boston, MA 02110-1301 USA |
| |
| @insertcopying |
| @end ifinfo |
| |
| |
| @setchapternewpage odd |
| |
| @titlepage |
| @title GNU Offloading and Multi Processing Runtime Library |
| @subtitle The GNU OpenMP and OpenACC Implementation |
| @page |
| @vskip 0pt plus 1filll |
| @comment For the @value{version-GCC} Version* |
| @sp 1 |
| Published by the Free Software Foundation @* |
| 51 Franklin Street, Fifth Floor@* |
| Boston, MA 02110-1301, USA@* |
| @sp 1 |
| @insertcopying |
| @end titlepage |
| |
| @summarycontents |
| @contents |
| @page |
| |
| |
| @node Top |
| @top Introduction |
| @cindex Introduction |
| |
| This manual documents the usage of libgomp, the GNU Offloading and |
| Multi Processing Runtime Library. This includes the GNU |
| implementation of the @uref{http://www.openmp.org, OpenMP} Application |
| Programming Interface (API) for multi-platform shared-memory parallel |
| programming in C/C++ and Fortran, and the GNU implementation of the |
| @uref{https://www.openacc.org, OpenACC} Application Programming |
| Interface (API) for offloading of code to accelerator devices in C/C++ |
| and Fortran. |
| |
| Originally, libgomp implemented the GNU OpenMP Runtime Library. Based |
| on this, support for OpenACC and offloading (both OpenACC and OpenMP |
| 4's target construct) has been added later on, and the library's name |
| changed to GNU Offloading and Multi Processing Runtime Library. |
| |
| |
| |
| @comment |
| @comment When you add a new menu item, please keep the right hand |
| @comment aligned to the same column. Do not use tabs. This provides |
| @comment better formatting. |
| @comment |
| @menu |
| * Enabling OpenMP:: How to enable OpenMP for your applications. |
| * Runtime Library Routines:: The OpenMP runtime application programming |
| interface. |
| * Environment Variables:: Influencing runtime behavior with environment |
| variables. |
| * Enabling OpenACC:: How to enable OpenACC for your |
| applications. |
| * OpenACC Runtime Library Routines:: The OpenACC runtime application |
| programming interface. |
| * OpenACC Environment Variables:: Influencing OpenACC runtime behavior with |
| environment variables. |
| * CUDA Streams Usage:: Notes on the implementation of |
| asynchronous operations. |
| * OpenACC Library Interoperability:: OpenACC library interoperability with the |
| NVIDIA CUBLAS library. |
| * The libgomp ABI:: Notes on the external ABI presented by libgomp. |
| * Reporting Bugs:: How to report bugs in the GNU Offloading and |
| Multi Processing Runtime Library. |
| * Copying:: GNU general public license says |
| how you can copy and share libgomp. |
| * GNU Free Documentation License:: |
| How you can copy and share this manual. |
| * Funding:: How to help assure continued work for free |
| software. |
| * Library Index:: Index of this documentation. |
| @end menu |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Enabling OpenMP |
| @c --------------------------------------------------------------------- |
| |
| @node Enabling OpenMP |
| @chapter Enabling OpenMP |
| |
| To activate the OpenMP extensions for C/C++ and Fortran, the compile-time |
| flag @command{-fopenmp} must be specified. This enables the OpenMP directive |
| @code{#pragma omp} in C/C++ and @code{!$omp} directives in free form, |
| @code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form, |
| @code{!$} conditional compilation sentinels in free form and @code{c$}, |
| @code{*$} and @code{!$} sentinels in fixed form, for Fortran. The flag also |
| arranges for automatic linking of the OpenMP runtime library |
| (@ref{Runtime Library Routines}). |
| |
| A complete description of all OpenMP directives accepted may be found in |
| the @uref{http://www.openmp.org, OpenMP Application Program Interface} manual, |
| version 4.5. |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Runtime Library Routines |
| @c --------------------------------------------------------------------- |
| |
| @node Runtime Library Routines |
| @chapter Runtime Library Routines |
| |
| The runtime routines described here are defined by Section 3 of the OpenMP |
| specification in version 4.5. The routines are structured in following |
| three parts: |
| |
| @menu |
| Control threads, processors and the parallel environment. They have C |
| linkage, and do not throw exceptions. |
| |
| * omp_get_active_level:: Number of active parallel regions |
| * omp_get_ancestor_thread_num:: Ancestor thread ID |
| * omp_get_cancellation:: Whether cancellation support is enabled |
| * omp_get_default_device:: Get the default device for target regions |
| * omp_get_dynamic:: Dynamic teams setting |
| * omp_get_level:: Number of parallel regions |
| * omp_get_max_active_levels:: Maximum number of active regions |
| * omp_get_max_task_priority:: Maximum task priority value that can be set |
| * omp_get_max_threads:: Maximum number of threads of parallel region |
| * omp_get_nested:: Nested parallel regions |
| * omp_get_num_devices:: Number of target devices |
| * omp_get_num_procs:: Number of processors online |
| * omp_get_num_teams:: Number of teams |
| * omp_get_num_threads:: Size of the active team |
| * omp_get_proc_bind:: Whether theads may be moved between CPUs |
| * omp_get_schedule:: Obtain the runtime scheduling method |
| * omp_get_team_num:: Get team number |
| * omp_get_team_size:: Number of threads in a team |
| * omp_get_thread_limit:: Maximum number of threads |
| * omp_get_thread_num:: Current thread ID |
| * omp_in_parallel:: Whether a parallel region is active |
| * omp_in_final:: Whether in final or included task region |
| * omp_is_initial_device:: Whether executing on the host device |
| * omp_set_default_device:: Set the default device for target regions |
| * omp_set_dynamic:: Enable/disable dynamic teams |
| * omp_set_max_active_levels:: Limits the number of active parallel regions |
| * omp_set_nested:: Enable/disable nested parallel regions |
| * omp_set_num_threads:: Set upper team size limit |
| * omp_set_schedule:: Set the runtime scheduling method |
| |
| Initialize, set, test, unset and destroy simple and nested locks. |
| |
| * omp_init_lock:: Initialize simple lock |
| * omp_set_lock:: Wait for and set simple lock |
| * omp_test_lock:: Test and set simple lock if available |
| * omp_unset_lock:: Unset simple lock |
| * omp_destroy_lock:: Destroy simple lock |
| * omp_init_nest_lock:: Initialize nested lock |
| * omp_set_nest_lock:: Wait for and set simple lock |
| * omp_test_nest_lock:: Test and set nested lock if available |
| * omp_unset_nest_lock:: Unset nested lock |
| * omp_destroy_nest_lock:: Destroy nested lock |
| |
| Portable, thread-based, wall clock timer. |
| |
| * omp_get_wtick:: Get timer precision. |
| * omp_get_wtime:: Elapsed wall clock time. |
| @end menu |
| |
| |
| |
| @node omp_get_active_level |
| @section @code{omp_get_active_level} -- Number of parallel regions |
| @table @asis |
| @item @emph{Description}: |
| This function returns the nesting level for the active parallel blocks, |
| which enclose the calling call. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_active_level(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_active_level()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_level}, @ref{omp_get_max_active_levels}, @ref{omp_set_max_active_levels} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.20. |
| @end table |
| |
| |
| |
| @node omp_get_ancestor_thread_num |
| @section @code{omp_get_ancestor_thread_num} -- Ancestor thread ID |
| @table @asis |
| @item @emph{Description}: |
| This function returns the thread identification number for the given |
| nesting level of the current thread. For values of @var{level} outside |
| zero to @code{omp_get_level} -1 is returned; if @var{level} is |
| @code{omp_get_level} the result is identical to @code{omp_get_thread_num}. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_ancestor_thread_num(int level);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_ancestor_thread_num(level)} |
| @item @tab @code{integer level} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_level}, @ref{omp_get_thread_num}, @ref{omp_get_team_size} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.18. |
| @end table |
| |
| |
| |
| @node omp_get_cancellation |
| @section @code{omp_get_cancellation} -- Whether cancellation support is enabled |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if cancellation is activated, @code{false} |
| otherwise. Here, @code{true} and @code{false} represent their language-specific |
| counterparts. Unless @env{OMP_CANCELLATION} is set true, cancellations are |
| deactivated. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_cancellation(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_get_cancellation()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_CANCELLATION} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.9. |
| @end table |
| |
| |
| |
| @node omp_get_default_device |
| @section @code{omp_get_default_device} -- Get the default device for target regions |
| @table @asis |
| @item @emph{Description}: |
| Get the default device for target regions without device clause. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_default_device(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_default_device()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_DEFAULT_DEVICE}, @ref{omp_set_default_device} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.30. |
| @end table |
| |
| |
| |
| @node omp_get_dynamic |
| @section @code{omp_get_dynamic} -- Dynamic teams setting |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if enabled, @code{false} otherwise. |
| Here, @code{true} and @code{false} represent their language-specific |
| counterparts. |
| |
| The dynamic team setting may be initialized at startup by the |
| @env{OMP_DYNAMIC} environment variable or at runtime using |
| @code{omp_set_dynamic}. If undefined, dynamic adjustment is |
| disabled by default. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_dynamic(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_get_dynamic()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_dynamic}, @ref{OMP_DYNAMIC} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.8. |
| @end table |
| |
| |
| |
| @node omp_get_level |
| @section @code{omp_get_level} -- Obtain the current nesting level |
| @table @asis |
| @item @emph{Description}: |
| This function returns the nesting level for the parallel blocks, |
| which enclose the calling call. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_level(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_level()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_active_level} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.17. |
| @end table |
| |
| |
| |
| @node omp_get_max_active_levels |
| @section @code{omp_get_max_active_levels} -- Maximum number of active regions |
| @table @asis |
| @item @emph{Description}: |
| This function obtains the maximum allowed number of nested, active parallel regions. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_max_active_levels(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_max_active_levels()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_max_active_levels}, @ref{omp_get_active_level} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.16. |
| @end table |
| |
| |
| @node omp_get_max_task_priority |
| @section @code{omp_get_max_task_priority} -- Maximum priority value |
| that can be set for tasks. |
| @table @asis |
| @item @emph{Description}: |
| This function obtains the maximum allowed priority number for tasks. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_max_task_priority(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_max_task_priority()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.29. |
| @end table |
| |
| |
| @node omp_get_max_threads |
| @section @code{omp_get_max_threads} -- Maximum number of threads of parallel region |
| @table @asis |
| @item @emph{Description}: |
| Return the maximum number of threads used for the current parallel region |
| that does not use the clause @code{num_threads}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_max_threads(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_max_threads()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_num_threads}, @ref{omp_set_dynamic}, @ref{omp_get_thread_limit} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.3. |
| @end table |
| |
| |
| |
| @node omp_get_nested |
| @section @code{omp_get_nested} -- Nested parallel regions |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if nested parallel regions are |
| enabled, @code{false} otherwise. Here, @code{true} and @code{false} |
| represent their language-specific counterparts. |
| |
| Nested parallel regions may be initialized at startup by the |
| @env{OMP_NESTED} environment variable or at runtime using |
| @code{omp_set_nested}. If undefined, nested parallel regions are |
| disabled by default. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_nested(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_get_nested()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_nested}, @ref{OMP_NESTED} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.11. |
| @end table |
| |
| |
| |
| @node omp_get_num_devices |
| @section @code{omp_get_num_devices} -- Number of target devices |
| @table @asis |
| @item @emph{Description}: |
| Returns the number of target devices. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_num_devices(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_num_devices()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.31. |
| @end table |
| |
| |
| |
| @node omp_get_num_procs |
| @section @code{omp_get_num_procs} -- Number of processors online |
| @table @asis |
| @item @emph{Description}: |
| Returns the number of processors online on that device. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_num_procs(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_num_procs()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.5. |
| @end table |
| |
| |
| |
| @node omp_get_num_teams |
| @section @code{omp_get_num_teams} -- Number of teams |
| @table @asis |
| @item @emph{Description}: |
| Returns the number of teams in the current team region. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_num_teams(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_num_teams()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.32. |
| @end table |
| |
| |
| |
| @node omp_get_num_threads |
| @section @code{omp_get_num_threads} -- Size of the active team |
| @table @asis |
| @item @emph{Description}: |
| Returns the number of threads in the current team. In a sequential section of |
| the program @code{omp_get_num_threads} returns 1. |
| |
| The default team size may be initialized at startup by the |
| @env{OMP_NUM_THREADS} environment variable. At runtime, the size |
| of the current team may be set either by the @code{NUM_THREADS} |
| clause or by @code{omp_set_num_threads}. If none of the above were |
| used to define a specific value and @env{OMP_DYNAMIC} is disabled, |
| one thread per CPU online is used. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_num_threads(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_num_threads()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_max_threads}, @ref{omp_set_num_threads}, @ref{OMP_NUM_THREADS} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.2. |
| @end table |
| |
| |
| |
| @node omp_get_proc_bind |
| @section @code{omp_get_proc_bind} -- Whether theads may be moved between CPUs |
| @table @asis |
| @item @emph{Description}: |
| This functions returns the currently active thread affinity policy, which is |
| set via @env{OMP_PROC_BIND}. Possible values are @code{omp_proc_bind_false}, |
| @code{omp_proc_bind_true}, @code{omp_proc_bind_master}, |
| @code{omp_proc_bind_close} and @code{omp_proc_bind_spread}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{omp_proc_bind_t omp_get_proc_bind(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer(kind=omp_proc_bind_kind) function omp_get_proc_bind()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_PROC_BIND}, @ref{OMP_PLACES}, @ref{GOMP_CPU_AFFINITY}, |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.22. |
| @end table |
| |
| |
| |
| @node omp_get_schedule |
| @section @code{omp_get_schedule} -- Obtain the runtime scheduling method |
| @table @asis |
| @item @emph{Description}: |
| Obtain the runtime scheduling method. The @var{kind} argument will be |
| set to the value @code{omp_sched_static}, @code{omp_sched_dynamic}, |
| @code{omp_sched_guided} or @code{omp_sched_auto}. The second argument, |
| @var{chunk_size}, is set to the chunk size. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_get_schedule(omp_sched_t *kind, int *chunk_size);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_get_schedule(kind, chunk_size)} |
| @item @tab @code{integer(kind=omp_sched_kind) kind} |
| @item @tab @code{integer chunk_size} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_schedule}, @ref{OMP_SCHEDULE} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.13. |
| @end table |
| |
| |
| |
| @node omp_get_team_num |
| @section @code{omp_get_team_num} -- Get team number |
| @table @asis |
| @item @emph{Description}: |
| Returns the team number of the calling thread. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_team_num(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_team_num()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.33. |
| @end table |
| |
| |
| |
| @node omp_get_team_size |
| @section @code{omp_get_team_size} -- Number of threads in a team |
| @table @asis |
| @item @emph{Description}: |
| This function returns the number of threads in a thread team to which |
| either the current thread or its ancestor belongs. For values of @var{level} |
| outside zero to @code{omp_get_level}, -1 is returned; if @var{level} is zero, |
| 1 is returned, and for @code{omp_get_level}, the result is identical |
| to @code{omp_get_num_threads}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_team_size(int level);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_team_size(level)} |
| @item @tab @code{integer level} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_num_threads}, @ref{omp_get_level}, @ref{omp_get_ancestor_thread_num} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.19. |
| @end table |
| |
| |
| |
| @node omp_get_thread_limit |
| @section @code{omp_get_thread_limit} -- Maximum number of threads |
| @table @asis |
| @item @emph{Description}: |
| Return the maximum number of threads of the program. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_thread_limit(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_thread_limit()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_max_threads}, @ref{OMP_THREAD_LIMIT} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.14. |
| @end table |
| |
| |
| |
| @node omp_get_thread_num |
| @section @code{omp_get_thread_num} -- Current thread ID |
| @table @asis |
| @item @emph{Description}: |
| Returns a unique thread identification number within the current team. |
| In a sequential parts of the program, @code{omp_get_thread_num} |
| always returns 0. In parallel regions the return value varies |
| from 0 to @code{omp_get_num_threads}-1 inclusive. The return |
| value of the master thread of a team is always 0. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_get_thread_num(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function omp_get_thread_num()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_num_threads}, @ref{omp_get_ancestor_thread_num} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.4. |
| @end table |
| |
| |
| |
| @node omp_in_parallel |
| @section @code{omp_in_parallel} -- Whether a parallel region is active |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if currently running in parallel, |
| @code{false} otherwise. Here, @code{true} and @code{false} represent |
| their language-specific counterparts. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_in_parallel(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_in_parallel()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.6. |
| @end table |
| |
| |
| @node omp_in_final |
| @section @code{omp_in_final} -- Whether in final or included task region |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if currently running in a final |
| or included task region, @code{false} otherwise. Here, @code{true} |
| and @code{false} represent their language-specific counterparts. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_in_final(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_in_final()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.21. |
| @end table |
| |
| |
| |
| @node omp_is_initial_device |
| @section @code{omp_is_initial_device} -- Whether executing on the host device |
| @table @asis |
| @item @emph{Description}: |
| This function returns @code{true} if currently running on the host device, |
| @code{false} otherwise. Here, @code{true} and @code{false} represent |
| their language-specific counterparts. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_is_initial_device(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_is_initial_device()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.34. |
| @end table |
| |
| |
| |
| @node omp_set_default_device |
| @section @code{omp_set_default_device} -- Set the default device for target regions |
| @table @asis |
| @item @emph{Description}: |
| Set the default device for target regions without device clause. The argument |
| shall be a nonnegative device number. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_default_device(int device_num);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_default_device(device_num)} |
| @item @tab @code{integer device_num} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_DEFAULT_DEVICE}, @ref{omp_get_default_device} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.29. |
| @end table |
| |
| |
| |
| @node omp_set_dynamic |
| @section @code{omp_set_dynamic} -- Enable/disable dynamic teams |
| @table @asis |
| @item @emph{Description}: |
| Enable or disable the dynamic adjustment of the number of threads |
| within a team. The function takes the language-specific equivalent |
| of @code{true} and @code{false}, where @code{true} enables dynamic |
| adjustment of team sizes and @code{false} disables it. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_dynamic(int dynamic_threads);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_dynamic(dynamic_threads)} |
| @item @tab @code{logical, intent(in) :: dynamic_threads} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_DYNAMIC}, @ref{omp_get_dynamic} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.7. |
| @end table |
| |
| |
| |
| @node omp_set_max_active_levels |
| @section @code{omp_set_max_active_levels} -- Limits the number of active parallel regions |
| @table @asis |
| @item @emph{Description}: |
| This function limits the maximum allowed number of nested, active |
| parallel regions. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_max_active_levels(int max_levels);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_max_active_levels(max_levels)} |
| @item @tab @code{integer max_levels} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_max_active_levels}, @ref{omp_get_active_level} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.15. |
| @end table |
| |
| |
| |
| @node omp_set_nested |
| @section @code{omp_set_nested} -- Enable/disable nested parallel regions |
| @table @asis |
| @item @emph{Description}: |
| Enable or disable nested parallel regions, i.e., whether team members |
| are allowed to create new teams. The function takes the language-specific |
| equivalent of @code{true} and @code{false}, where @code{true} enables |
| dynamic adjustment of team sizes and @code{false} disables it. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_nested(int nested);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_nested(nested)} |
| @item @tab @code{logical, intent(in) :: nested} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_NESTED}, @ref{omp_get_nested} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.10. |
| @end table |
| |
| |
| |
| @node omp_set_num_threads |
| @section @code{omp_set_num_threads} -- Set upper team size limit |
| @table @asis |
| @item @emph{Description}: |
| Specifies the number of threads used by default in subsequent parallel |
| sections, if those do not specify a @code{num_threads} clause. The |
| argument of @code{omp_set_num_threads} shall be a positive integer. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_num_threads(int num_threads);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_num_threads(num_threads)} |
| @item @tab @code{integer, intent(in) :: num_threads} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{OMP_NUM_THREADS}, @ref{omp_get_num_threads}, @ref{omp_get_max_threads} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.1. |
| @end table |
| |
| |
| |
| @node omp_set_schedule |
| @section @code{omp_set_schedule} -- Set the runtime scheduling method |
| @table @asis |
| @item @emph{Description}: |
| Sets the runtime scheduling method. The @var{kind} argument can have the |
| value @code{omp_sched_static}, @code{omp_sched_dynamic}, |
| @code{omp_sched_guided} or @code{omp_sched_auto}. Except for |
| @code{omp_sched_auto}, the chunk size is set to the value of |
| @var{chunk_size} if positive, or to the default value if zero or negative. |
| For @code{omp_sched_auto} the @var{chunk_size} argument is ignored. |
| |
| @item @emph{C/C++} |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_schedule(omp_sched_t kind, int chunk_size);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_schedule(kind, chunk_size)} |
| @item @tab @code{integer(kind=omp_sched_kind) kind} |
| @item @tab @code{integer chunk_size} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_schedule} |
| @ref{OMP_SCHEDULE} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.2.12. |
| @end table |
| |
| |
| |
| @node omp_init_lock |
| @section @code{omp_init_lock} -- Initialize simple lock |
| @table @asis |
| @item @emph{Description}: |
| Initialize a simple lock. After initialization, the lock is in |
| an unlocked state. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_init_lock(omp_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_init_lock(svar)} |
| @item @tab @code{integer(omp_lock_kind), intent(out) :: svar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_destroy_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.1. |
| @end table |
| |
| |
| |
| @node omp_set_lock |
| @section @code{omp_set_lock} -- Wait for and set simple lock |
| @table @asis |
| @item @emph{Description}: |
| Before setting a simple lock, the lock variable must be initialized by |
| @code{omp_init_lock}. The calling thread is blocked until the lock |
| is available. If the lock is already held by the current thread, |
| a deadlock occurs. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_lock(omp_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_lock(svar)} |
| @item @tab @code{integer(omp_lock_kind), intent(inout) :: svar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_init_lock}, @ref{omp_test_lock}, @ref{omp_unset_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.4. |
| @end table |
| |
| |
| |
| @node omp_test_lock |
| @section @code{omp_test_lock} -- Test and set simple lock if available |
| @table @asis |
| @item @emph{Description}: |
| Before setting a simple lock, the lock variable must be initialized by |
| @code{omp_init_lock}. Contrary to @code{omp_set_lock}, @code{omp_test_lock} |
| does not block if the lock is not available. This function returns |
| @code{true} upon success, @code{false} otherwise. Here, @code{true} and |
| @code{false} represent their language-specific counterparts. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_test_lock(omp_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_test_lock(svar)} |
| @item @tab @code{integer(omp_lock_kind), intent(inout) :: svar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_init_lock}, @ref{omp_set_lock}, @ref{omp_set_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.6. |
| @end table |
| |
| |
| |
| @node omp_unset_lock |
| @section @code{omp_unset_lock} -- Unset simple lock |
| @table @asis |
| @item @emph{Description}: |
| A simple lock about to be unset must have been locked by @code{omp_set_lock} |
| or @code{omp_test_lock} before. In addition, the lock must be held by the |
| thread calling @code{omp_unset_lock}. Then, the lock becomes unlocked. If one |
| or more threads attempted to set the lock before, one of them is chosen to, |
| again, set the lock to itself. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_unset_lock(omp_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_unset_lock(svar)} |
| @item @tab @code{integer(omp_lock_kind), intent(inout) :: svar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_lock}, @ref{omp_test_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.5. |
| @end table |
| |
| |
| |
| @node omp_destroy_lock |
| @section @code{omp_destroy_lock} -- Destroy simple lock |
| @table @asis |
| @item @emph{Description}: |
| Destroy a simple lock. In order to be destroyed, a simple lock must be |
| in the unlocked state. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_destroy_lock(omp_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_destroy_lock(svar)} |
| @item @tab @code{integer(omp_lock_kind), intent(inout) :: svar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_init_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.3. |
| @end table |
| |
| |
| |
| @node omp_init_nest_lock |
| @section @code{omp_init_nest_lock} -- Initialize nested lock |
| @table @asis |
| @item @emph{Description}: |
| Initialize a nested lock. After initialization, the lock is in |
| an unlocked state and the nesting count is set to zero. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_init_nest_lock(omp_nest_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_init_nest_lock(nvar)} |
| @item @tab @code{integer(omp_nest_lock_kind), intent(out) :: nvar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_destroy_nest_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.1. |
| @end table |
| |
| |
| @node omp_set_nest_lock |
| @section @code{omp_set_nest_lock} -- Wait for and set nested lock |
| @table @asis |
| @item @emph{Description}: |
| Before setting a nested lock, the lock variable must be initialized by |
| @code{omp_init_nest_lock}. The calling thread is blocked until the lock |
| is available. If the lock is already held by the current thread, the |
| nesting count for the lock is incremented. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_set_nest_lock(omp_nest_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_set_nest_lock(nvar)} |
| @item @tab @code{integer(omp_nest_lock_kind), intent(inout) :: nvar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_init_nest_lock}, @ref{omp_unset_nest_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.4. |
| @end table |
| |
| |
| |
| @node omp_test_nest_lock |
| @section @code{omp_test_nest_lock} -- Test and set nested lock if available |
| @table @asis |
| @item @emph{Description}: |
| Before setting a nested lock, the lock variable must be initialized by |
| @code{omp_init_nest_lock}. Contrary to @code{omp_set_nest_lock}, |
| @code{omp_test_nest_lock} does not block if the lock is not available. |
| If the lock is already held by the current thread, the new nesting count |
| is returned. Otherwise, the return value equals zero. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int omp_test_nest_lock(omp_nest_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{logical function omp_test_nest_lock(nvar)} |
| @item @tab @code{integer(omp_nest_lock_kind), intent(inout) :: nvar} |
| @end multitable |
| |
| |
| @item @emph{See also}: |
| @ref{omp_init_lock}, @ref{omp_set_lock}, @ref{omp_set_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.6. |
| @end table |
| |
| |
| |
| @node omp_unset_nest_lock |
| @section @code{omp_unset_nest_lock} -- Unset nested lock |
| @table @asis |
| @item @emph{Description}: |
| A nested lock about to be unset must have been locked by @code{omp_set_nested_lock} |
| or @code{omp_test_nested_lock} before. In addition, the lock must be held by the |
| thread calling @code{omp_unset_nested_lock}. If the nesting count drops to zero, the |
| lock becomes unlocked. If one ore more threads attempted to set the lock before, |
| one of them is chosen to, again, set the lock to itself. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_unset_nest_lock(omp_nest_lock_t *lock);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_unset_nest_lock(nvar)} |
| @item @tab @code{integer(omp_nest_lock_kind), intent(inout) :: nvar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_set_nest_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.5. |
| @end table |
| |
| |
| |
| @node omp_destroy_nest_lock |
| @section @code{omp_destroy_nest_lock} -- Destroy nested lock |
| @table @asis |
| @item @emph{Description}: |
| Destroy a nested lock. In order to be destroyed, a nested lock must be |
| in the unlocked state and its nesting count must equal zero. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void omp_destroy_nest_lock(omp_nest_lock_t *);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine omp_destroy_nest_lock(nvar)} |
| @item @tab @code{integer(omp_nest_lock_kind), intent(inout) :: nvar} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_init_lock} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.3.3. |
| @end table |
| |
| |
| |
| @node omp_get_wtick |
| @section @code{omp_get_wtick} -- Get timer precision |
| @table @asis |
| @item @emph{Description}: |
| Gets the timer precision, i.e., the number of seconds between two |
| successive clock ticks. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{double omp_get_wtick(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{double precision function omp_get_wtick()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_wtime} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.4.2. |
| @end table |
| |
| |
| |
| @node omp_get_wtime |
| @section @code{omp_get_wtime} -- Elapsed wall clock time |
| @table @asis |
| @item @emph{Description}: |
| Elapsed wall clock time in seconds. The time is measured per thread, no |
| guarantee can be made that two distinct threads measure the same time. |
| Time is measured from some "time in the past", which is an arbitrary time |
| guaranteed not to change during the execution of the program. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{double omp_get_wtime(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{double precision function omp_get_wtime()} |
| @end multitable |
| |
| @item @emph{See also}: |
| @ref{omp_get_wtick} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 3.4.1. |
| @end table |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Environment Variables |
| @c --------------------------------------------------------------------- |
| |
| @node Environment Variables |
| @chapter Environment Variables |
| |
| The environment variables which beginning with @env{OMP_} are defined by |
| section 4 of the OpenMP specification in version 4.5, while those |
| beginning with @env{GOMP_} are GNU extensions. |
| |
| @menu |
| * OMP_CANCELLATION:: Set whether cancellation is activated |
| * OMP_DISPLAY_ENV:: Show OpenMP version and environment variables |
| * OMP_DEFAULT_DEVICE:: Set the device used in target regions |
| * OMP_DYNAMIC:: Dynamic adjustment of threads |
| * OMP_MAX_ACTIVE_LEVELS:: Set the maximum number of nested parallel regions |
| * OMP_MAX_TASK_PRIORITY:: Set the maximum task priority value |
| * OMP_NESTED:: Nested parallel regions |
| * OMP_NUM_THREADS:: Specifies the number of threads to use |
| * OMP_PROC_BIND:: Whether theads may be moved between CPUs |
| * OMP_PLACES:: Specifies on which CPUs the theads should be placed |
| * OMP_STACKSIZE:: Set default thread stack size |
| * OMP_SCHEDULE:: How threads are scheduled |
| * OMP_THREAD_LIMIT:: Set the maximum number of threads |
| * OMP_WAIT_POLICY:: How waiting threads are handled |
| * GOMP_CPU_AFFINITY:: Bind threads to specific CPUs |
| * GOMP_DEBUG:: Enable debugging output |
| * GOMP_STACKSIZE:: Set default thread stack size |
| * GOMP_SPINCOUNT:: Set the busy-wait spin count |
| * GOMP_RTEMS_THREAD_POOLS:: Set the RTEMS specific thread pools |
| @end menu |
| |
| |
| @node OMP_CANCELLATION |
| @section @env{OMP_CANCELLATION} -- Set whether cancellation is activated |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| If set to @code{TRUE}, the cancellation is activated. If set to @code{FALSE} or |
| if unset, cancellation is disabled and the @code{cancel} construct is ignored. |
| |
| @item @emph{See also}: |
| @ref{omp_get_cancellation} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.11 |
| @end table |
| |
| |
| |
| @node OMP_DISPLAY_ENV |
| @section @env{OMP_DISPLAY_ENV} -- Show OpenMP version and environment variables |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| If set to @code{TRUE}, the OpenMP version number and the values |
| associated with the OpenMP environment variables are printed to @code{stderr}. |
| If set to @code{VERBOSE}, it additionally shows the value of the environment |
| variables which are GNU extensions. If undefined or set to @code{FALSE}, |
| this information will not be shown. |
| |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.12 |
| @end table |
| |
| |
| |
| @node OMP_DEFAULT_DEVICE |
| @section @env{OMP_DEFAULT_DEVICE} -- Set the device used in target regions |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Set to choose the device which is used in a @code{target} region, unless the |
| value is overridden by @code{omp_set_default_device} or by a @code{device} |
| clause. The value shall be the nonnegative device number. If no device with |
| the given device number exists, the code is executed on the host. If unset, |
| device number 0 will be used. |
| |
| |
| @item @emph{See also}: |
| @ref{omp_get_default_device}, @ref{omp_set_default_device}, |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.13 |
| @end table |
| |
| |
| |
| @node OMP_DYNAMIC |
| @section @env{OMP_DYNAMIC} -- Dynamic adjustment of threads |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Enable or disable the dynamic adjustment of the number of threads |
| within a team. The value of this environment variable shall be |
| @code{TRUE} or @code{FALSE}. If undefined, dynamic adjustment is |
| disabled by default. |
| |
| @item @emph{See also}: |
| @ref{omp_set_dynamic} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.3 |
| @end table |
| |
| |
| |
| @node OMP_MAX_ACTIVE_LEVELS |
| @section @env{OMP_MAX_ACTIVE_LEVELS} -- Set the maximum number of nested parallel regions |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Specifies the initial value for the maximum number of nested parallel |
| regions. The value of this variable shall be a positive integer. |
| If undefined, the number of active levels is unlimited. |
| |
| @item @emph{See also}: |
| @ref{omp_set_max_active_levels} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.9 |
| @end table |
| |
| |
| |
| @node OMP_MAX_TASK_PRIORITY |
| @section @env{OMP_MAX_TASK_PRIORITY} -- Set the maximum priority |
| number that can be set for a task. |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Specifies the initial value for the maximum priority value that can be |
| set for a task. The value of this variable shall be a non-negative |
| integer, and zero is allowed. If undefined, the default priority is |
| 0. |
| |
| @item @emph{See also}: |
| @ref{omp_get_max_task_priority} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.14 |
| @end table |
| |
| |
| |
| @node OMP_NESTED |
| @section @env{OMP_NESTED} -- Nested parallel regions |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| Enable or disable nested parallel regions, i.e., whether team members |
| are allowed to create new teams. The value of this environment variable |
| shall be @code{TRUE} or @code{FALSE}. If undefined, nested parallel |
| regions are disabled by default. |
| |
| @item @emph{See also}: |
| @ref{omp_set_nested} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.6 |
| @end table |
| |
| |
| |
| @node OMP_NUM_THREADS |
| @section @env{OMP_NUM_THREADS} -- Specifies the number of threads to use |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| Specifies the default number of threads to use in parallel regions. The |
| value of this variable shall be a comma-separated list of positive integers; |
| the value specified the number of threads to use for the corresponding nested |
| level. If undefined one thread per CPU is used. |
| |
| @item @emph{See also}: |
| @ref{omp_set_num_threads} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.2 |
| @end table |
| |
| |
| |
| @node OMP_PROC_BIND |
| @section @env{OMP_PROC_BIND} -- Whether theads may be moved between CPUs |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Specifies whether threads may be moved between processors. If set to |
| @code{TRUE}, OpenMP theads should not be moved; if set to @code{FALSE} |
| they may be moved. Alternatively, a comma separated list with the |
| values @code{MASTER}, @code{CLOSE} and @code{SPREAD} can be used to specify |
| the thread affinity policy for the corresponding nesting level. With |
| @code{MASTER} the worker threads are in the same place partition as the |
| master thread. With @code{CLOSE} those are kept close to the master thread |
| in contiguous place partitions. And with @code{SPREAD} a sparse distribution |
| across the place partitions is used. |
| |
| When undefined, @env{OMP_PROC_BIND} defaults to @code{TRUE} when |
| @env{OMP_PLACES} or @env{GOMP_CPU_AFFINITY} is set and @code{FALSE} otherwise. |
| |
| @item @emph{See also}: |
| @ref{OMP_PLACES}, @ref{GOMP_CPU_AFFINITY}, @ref{omp_get_proc_bind} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.4 |
| @end table |
| |
| |
| |
| @node OMP_PLACES |
| @section @env{OMP_PLACES} -- Specifies on which CPUs the theads should be placed |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| The thread placement can be either specified using an abstract name or by an |
| explicit list of the places. The abstract names @code{threads}, @code{cores} |
| and @code{sockets} can be optionally followed by a positive number in |
| parentheses, which denotes the how many places shall be created. With |
| @code{threads} each place corresponds to a single hardware thread; @code{cores} |
| to a single core with the corresponding number of hardware threads; and with |
| @code{sockets} the place corresponds to a single socket. The resulting |
| placement can be shown by setting the @env{OMP_DISPLAY_ENV} environment |
| variable. |
| |
| Alternatively, the placement can be specified explicitly as comma-separated |
| list of places. A place is specified by set of nonnegative numbers in curly |
| braces, denoting the denoting the hardware threads. The hardware threads |
| belonging to a place can either be specified as comma-separated list of |
| nonnegative thread numbers or using an interval. Multiple places can also be |
| either specified by a comma-separated list of places or by an interval. To |
| specify an interval, a colon followed by the count is placed after after |
| the hardware thread number or the place. Optionally, the length can be |
| followed by a colon and the stride number -- otherwise a unit stride is |
| assumed. For instance, the following specifies the same places list: |
| @code{"@{0,1,2@}, @{3,4,6@}, @{7,8,9@}, @{10,11,12@}"}; |
| @code{"@{0:3@}, @{3:3@}, @{7:3@}, @{10:3@}"}; and @code{"@{0:2@}:4:3"}. |
| |
| If @env{OMP_PLACES} and @env{GOMP_CPU_AFFINITY} are unset and |
| @env{OMP_PROC_BIND} is either unset or @code{false}, threads may be moved |
| between CPUs following no placement policy. |
| |
| @item @emph{See also}: |
| @ref{OMP_PROC_BIND}, @ref{GOMP_CPU_AFFINITY}, @ref{omp_get_proc_bind}, |
| @ref{OMP_DISPLAY_ENV} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.5 |
| @end table |
| |
| |
| |
| @node OMP_STACKSIZE |
| @section @env{OMP_STACKSIZE} -- Set default thread stack size |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Set the default thread stack size in kilobytes, unless the number |
| is suffixed by @code{B}, @code{K}, @code{M} or @code{G}, in which |
| case the size is, respectively, in bytes, kilobytes, megabytes |
| or gigabytes. This is different from @code{pthread_attr_setstacksize} |
| which gets the number of bytes as an argument. If the stack size cannot |
| be set due to system constraints, an error is reported and the initial |
| stack size is left unchanged. If undefined, the stack size is system |
| dependent. |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.7 |
| @end table |
| |
| |
| |
| @node OMP_SCHEDULE |
| @section @env{OMP_SCHEDULE} -- How threads are scheduled |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| Allows to specify @code{schedule type} and @code{chunk size}. |
| The value of the variable shall have the form: @code{type[,chunk]} where |
| @code{type} is one of @code{static}, @code{dynamic}, @code{guided} or @code{auto} |
| The optional @code{chunk} size shall be a positive integer. If undefined, |
| dynamic scheduling and a chunk size of 1 is used. |
| |
| @item @emph{See also}: |
| @ref{omp_set_schedule} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Sections 2.7.1.1 and 4.1 |
| @end table |
| |
| |
| |
| @node OMP_THREAD_LIMIT |
| @section @env{OMP_THREAD_LIMIT} -- Set the maximum number of threads |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Specifies the number of threads to use for the whole program. The |
| value of this variable shall be a positive integer. If undefined, |
| the number of threads is not limited. |
| |
| @item @emph{See also}: |
| @ref{OMP_NUM_THREADS}, @ref{omp_get_thread_limit} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.10 |
| @end table |
| |
| |
| |
| @node OMP_WAIT_POLICY |
| @section @env{OMP_WAIT_POLICY} -- How waiting threads are handled |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Specifies whether waiting threads should be active or passive. If |
| the value is @code{PASSIVE}, waiting threads should not consume CPU |
| power while waiting; while the value is @code{ACTIVE} specifies that |
| they should. If undefined, threads wait actively for a short time |
| before waiting passively. |
| |
| @item @emph{See also}: |
| @ref{GOMP_SPINCOUNT} |
| |
| @item @emph{Reference}: |
| @uref{http://www.openmp.org/, OpenMP specification v4.5}, Section 4.8 |
| @end table |
| |
| |
| |
| @node GOMP_CPU_AFFINITY |
| @section @env{GOMP_CPU_AFFINITY} -- Bind threads to specific CPUs |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Binds threads to specific CPUs. The variable should contain a space-separated |
| or comma-separated list of CPUs. This list may contain different kinds of |
| entries: either single CPU numbers in any order, a range of CPUs (M-N) |
| or a range with some stride (M-N:S). CPU numbers are zero based. For example, |
| @code{GOMP_CPU_AFFINITY="0 3 1-2 4-15:2"} will bind the initial thread |
| to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to |
| CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8, 10, 12, |
| and 14 respectively and then start assigning back from the beginning of |
| the list. @code{GOMP_CPU_AFFINITY=0} binds all threads to CPU 0. |
| |
| There is no libgomp library routine to determine whether a CPU affinity |
| specification is in effect. As a workaround, language-specific library |
| functions, e.g., @code{getenv} in C or @code{GET_ENVIRONMENT_VARIABLE} in |
| Fortran, may be used to query the setting of the @code{GOMP_CPU_AFFINITY} |
| environment variable. A defined CPU affinity on startup cannot be changed |
| or disabled during the runtime of the application. |
| |
| If both @env{GOMP_CPU_AFFINITY} and @env{OMP_PROC_BIND} are set, |
| @env{OMP_PROC_BIND} has a higher precedence. If neither has been set and |
| @env{OMP_PROC_BIND} is unset, or when @env{OMP_PROC_BIND} is set to |
| @code{FALSE}, the host system will handle the assignment of threads to CPUs. |
| |
| @item @emph{See also}: |
| @ref{OMP_PLACES}, @ref{OMP_PROC_BIND} |
| @end table |
| |
| |
| |
| @node GOMP_DEBUG |
| @section @env{GOMP_DEBUG} -- Enable debugging output |
| @cindex Environment Variable |
| @table @asis |
| @item @emph{Description}: |
| Enable debugging output. The variable should be set to @code{0} |
| (disabled, also the default if not set), or @code{1} (enabled). |
| |
| If enabled, some debugging output will be printed during execution. |
| This is currently not specified in more detail, and subject to change. |
| @end table |
| |
| |
| |
| @node GOMP_STACKSIZE |
| @section @env{GOMP_STACKSIZE} -- Set default thread stack size |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| Set the default thread stack size in kilobytes. This is different from |
| @code{pthread_attr_setstacksize} which gets the number of bytes as an |
| argument. If the stack size cannot be set due to system constraints, an |
| error is reported and the initial stack size is left unchanged. If undefined, |
| the stack size is system dependent. |
| |
| @item @emph{See also}: |
| @ref{OMP_STACKSIZE} |
| |
| @item @emph{Reference}: |
| @uref{http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00493.html, |
| GCC Patches Mailinglist}, |
| @uref{http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00496.html, |
| GCC Patches Mailinglist} |
| @end table |
| |
| |
| |
| @node GOMP_SPINCOUNT |
| @section @env{GOMP_SPINCOUNT} -- Set the busy-wait spin count |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| Determines how long a threads waits actively with consuming CPU power |
| before waiting passively without consuming CPU power. The value may be |
| either @code{INFINITE}, @code{INFINITY} to always wait actively or an |
| integer which gives the number of spins of the busy-wait loop. The |
| integer may optionally be followed by the following suffixes acting |
| as multiplication factors: @code{k} (kilo, thousand), @code{M} (mega, |
| million), @code{G} (giga, billion), or @code{T} (tera, trillion). |
| If undefined, 0 is used when @env{OMP_WAIT_POLICY} is @code{PASSIVE}, |
| 300,000 is used when @env{OMP_WAIT_POLICY} is undefined and |
| 30 billion is used when @env{OMP_WAIT_POLICY} is @code{ACTIVE}. |
| If there are more OpenMP threads than available CPUs, 1000 and 100 |
| spins are used for @env{OMP_WAIT_POLICY} being @code{ACTIVE} or |
| undefined, respectively; unless the @env{GOMP_SPINCOUNT} is lower |
| or @env{OMP_WAIT_POLICY} is @code{PASSIVE}. |
| |
| @item @emph{See also}: |
| @ref{OMP_WAIT_POLICY} |
| @end table |
| |
| |
| |
| @node GOMP_RTEMS_THREAD_POOLS |
| @section @env{GOMP_RTEMS_THREAD_POOLS} -- Set the RTEMS specific thread pools |
| @cindex Environment Variable |
| @cindex Implementation specific setting |
| @table @asis |
| @item @emph{Description}: |
| This environment variable is only used on the RTEMS real-time operating system. |
| It determines the scheduler instance specific thread pools. The format for |
| @env{GOMP_RTEMS_THREAD_POOLS} is a list of optional |
| @code{<thread-pool-count>[$<priority>]@@<scheduler-name>} configurations |
| separated by @code{:} where: |
| @itemize @bullet |
| @item @code{<thread-pool-count>} is the thread pool count for this scheduler |
| instance. |
| @item @code{$<priority>} is an optional priority for the worker threads of a |
| thread pool according to @code{pthread_setschedparam}. In case a priority |
| value is omitted, then a worker thread will inherit the priority of the OpenMP |
| master thread that created it. The priority of the worker thread is not |
| changed after creation, even if a new OpenMP master thread using the worker has |
| a different priority. |
| @item @code{@@<scheduler-name>} is the scheduler instance name according to the |
| RTEMS application configuration. |
| @end itemize |
| In case no thread pool configuration is specified for a scheduler instance, |
| then each OpenMP master thread of this scheduler instance will use its own |
| dynamically allocated thread pool. To limit the worker thread count of the |
| thread pools, each OpenMP master thread must call @code{omp_set_num_threads}. |
| @item @emph{Example}: |
| Lets suppose we have three scheduler instances @code{IO}, @code{WRK0}, and |
| @code{WRK1} with @env{GOMP_RTEMS_THREAD_POOLS} set to |
| @code{"1@@WRK0:3$4@@WRK1"}. Then there are no thread pool restrictions for |
| scheduler instance @code{IO}. In the scheduler instance @code{WRK0} there is |
| one thread pool available. Since no priority is specified for this scheduler |
| instance, the worker thread inherits the priority of the OpenMP master thread |
| that created it. In the scheduler instance @code{WRK1} there are three thread |
| pools available and their worker threads run at priority four. |
| @end table |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Enabling OpenACC |
| @c --------------------------------------------------------------------- |
| |
| @node Enabling OpenACC |
| @chapter Enabling OpenACC |
| |
| To activate the OpenACC extensions for C/C++ and Fortran, the compile-time |
| flag @option{-fopenacc} must be specified. This enables the OpenACC directive |
| @code{#pragma acc} in C/C++ and @code{!$accp} directives in free form, |
| @code{c$acc}, @code{*$acc} and @code{!$acc} directives in fixed form, |
| @code{!$} conditional compilation sentinels in free form and @code{c$}, |
| @code{*$} and @code{!$} sentinels in fixed form, for Fortran. The flag also |
| arranges for automatic linking of the OpenACC runtime library |
| (@ref{OpenACC Runtime Library Routines}). |
| |
| A complete description of all OpenACC directives accepted may be found in |
| the @uref{https://www.openacc.org, OpenACC} Application Programming |
| Interface manual, version 2.0. |
| |
| Note that this is an experimental feature and subject to |
| change in future versions of GCC. See |
| @uref{https://gcc.gnu.org/wiki/OpenACC} for more information. |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c OpenACC Runtime Library Routines |
| @c --------------------------------------------------------------------- |
| |
| @node OpenACC Runtime Library Routines |
| @chapter OpenACC Runtime Library Routines |
| |
| The runtime routines described here are defined by section 3 of the OpenACC |
| specifications in version 2.0. |
| They have C linkage, and do not throw exceptions. |
| Generally, they are available only for the host, with the exception of |
| @code{acc_on_device}, which is available for both the host and the |
| acceleration device. |
| |
| @menu |
| * acc_get_num_devices:: Get number of devices for the given device |
| type. |
| * acc_set_device_type:: Set type of device accelerator to use. |
| * acc_get_device_type:: Get type of device accelerator to be used. |
| * acc_set_device_num:: Set device number to use. |
| * acc_get_device_num:: Get device number to be used. |
| * acc_async_test:: Tests for completion of a specific asynchronous |
| operation. |
| * acc_async_test_all:: Tests for completion of all asychronous |
| operations. |
| * acc_wait:: Wait for completion of a specific asynchronous |
| operation. |
| * acc_wait_all:: Waits for completion of all asyncrhonous |
| operations. |
| * acc_wait_all_async:: Wait for completion of all asynchronous |
| operations. |
| * acc_wait_async:: Wait for completion of asynchronous operations. |
| * acc_init:: Initialize runtime for a specific device type. |
| * acc_shutdown:: Shuts down the runtime for a specific device |
| type. |
| * acc_on_device:: Whether executing on a particular device |
| * acc_malloc:: Allocate device memory. |
| * acc_free:: Free device memory. |
| * acc_copyin:: Allocate device memory and copy host memory to |
| it. |
| * acc_present_or_copyin:: If the data is not present on the device, |
| allocate device memory and copy from host |
| memory. |
| * acc_create:: Allocate device memory and map it to host |
| memory. |
| * acc_present_or_create:: If the data is not present on the device, |
| allocate device memory and map it to host |
| memory. |
| * acc_copyout:: Copy device memory to host memory. |
| * acc_delete:: Free device memory. |
| * acc_update_device:: Update device memory from mapped host memory. |
| * acc_update_self:: Update host memory from mapped device memory. |
| * acc_map_data:: Map previously allocated device memory to host |
| memory. |
| * acc_unmap_data:: Unmap device memory from host memory. |
| * acc_deviceptr:: Get device pointer associated with specific |
| host address. |
| * acc_hostptr:: Get host pointer associated with specific |
| device address. |
| * acc_is_present:: Indiciate whether host variable / array is |
| present on device. |
| * acc_memcpy_to_device:: Copy host memory to device memory. |
| * acc_memcpy_from_device:: Copy device memory to host memory. |
| |
| API routines for target platforms. |
| |
| * acc_get_current_cuda_device:: Get CUDA device handle. |
| * acc_get_current_cuda_context::Get CUDA context handle. |
| * acc_get_cuda_stream:: Get CUDA stream handle. |
| * acc_set_cuda_stream:: Set CUDA stream handle. |
| @end menu |
| |
| |
| |
| @node acc_get_num_devices |
| @section @code{acc_get_num_devices} -- Get number of devices for given device type |
| @table @asis |
| @item @emph{Description} |
| This function returns a value indicating the number of devices available |
| for the device type specified in @var{devicetype}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int acc_get_num_devices(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{integer function acc_get_num_devices(devicetype)} |
| @item @tab @code{integer(kind=acc_device_kind) devicetype} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.1. |
| @end table |
| |
| |
| |
| @node acc_set_device_type |
| @section @code{acc_set_device_type} -- Set type of device accelerator to use. |
| @table @asis |
| @item @emph{Description} |
| This function indicates to the runtime library which device typr, specified |
| in @var{devicetype}, to use when executing a parallel or kernels region. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_set_device_type(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_set_device_type(devicetype)} |
| @item @tab @code{integer(kind=acc_device_kind) devicetype} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.2. |
| @end table |
| |
| |
| |
| @node acc_get_device_type |
| @section @code{acc_get_device_type} -- Get type of device accelerator to be used. |
| @table @asis |
| @item @emph{Description} |
| This function returns what device type will be used when executing a |
| parallel or kernels region. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_device_t acc_get_device_type(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_get_device_type(void)} |
| @item @tab @code{integer(kind=acc_device_kind) acc_get_device_type} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.3. |
| @end table |
| |
| |
| |
| @node acc_set_device_num |
| @section @code{acc_set_device_num} -- Set device number to use. |
| @table @asis |
| @item @emph{Description} |
| This function will indicate to the runtime which device number, |
| specified by @var{num}, associated with the specifed device |
| type @var{devicetype}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_set_device_num(int num, acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_set_device_num(devicenum, devicetype)} |
| @item @tab @code{integer devicenum} |
| @item @tab @code{integer(kind=acc_device_kind) devicetype} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.4. |
| @end table |
| |
| |
| |
| @node acc_get_device_num |
| @section @code{acc_get_device_num} -- Get device number to be used. |
| @table @asis |
| @item @emph{Description} |
| This function returns which device number associated with the specified device |
| type @var{devicetype}, will be used when executing a parallel or kernels |
| region. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int acc_get_device_num(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_get_device_num(devicetype)} |
| @item @tab @code{integer(kind=acc_device_kind) devicetype} |
| @item @tab @code{integer acc_get_device_num} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.5. |
| @end table |
| |
| |
| |
| @node acc_async_test |
| @section @code{acc_async_test} -- Test for completion of a specific asynchronous operation. |
| @table @asis |
| @item @emph{Description} |
| This function tests for completion of the asynchrounous operation specified |
| in @var{arg}. In C/C++, a non-zero value will be returned to indicate |
| the specified asynchronous operation has completed. While Fortran will return |
| a @code{true}. If the asynchrounous operation has not completed, C/C++ returns |
| a zero and Fortran returns a @code{false}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int acc_async_test(int arg);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_async_test(arg)} |
| @item @tab @code{integer(kind=acc_handle_kind) arg} |
| @item @tab @code{logical acc_async_test} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.6. |
| @end table |
| |
| |
| |
| @node acc_async_test_all |
| @section @code{acc_async_test_all} -- Tests for completion of all asynchronous operations. |
| @table @asis |
| @item @emph{Description} |
| This function tests for completion of all asynchrounous operations. |
| In C/C++, a non-zero value will be returned to indicate all asynchronous |
| operations have completed. While Fortran will return a @code{true}. If |
| any asynchronous operation has not completed, C/C++ returns a zero and |
| Fortran returns a @code{false}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int acc_async_test_all(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_async_test()} |
| @item @tab @code{logical acc_get_device_num} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.7. |
| @end table |
| |
| |
| |
| @node acc_wait |
| @section @code{acc_wait} -- Wait for completion of a specific asynchronous operation. |
| @table @asis |
| @item @emph{Description} |
| This function waits for completion of the asynchronous operation |
| specified in @var{arg}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_wait(arg);} |
| @item @emph{Prototype (OpenACC 1.0 compatibility)}: @tab @code{acc_async_wait(arg);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_wait(arg)} |
| @item @tab @code{integer(acc_handle_kind) arg} |
| @item @emph{Interface (OpenACC 1.0 compatibility)}: @tab @code{subroutine acc_async_wait(arg)} |
| @item @tab @code{integer(acc_handle_kind) arg} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.8. |
| @end table |
| |
| |
| |
| @node acc_wait_all |
| @section @code{acc_wait_all} -- Waits for completion of all asynchronous operations. |
| @table @asis |
| @item @emph{Description} |
| This function waits for the completion of all asynchronous operations. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_wait_all(void);} |
| @item @emph{Prototype (OpenACC 1.0 compatibility)}: @tab @code{acc_async_wait_all(void);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_wait_all()} |
| @item @emph{Interface (OpenACC 1.0 compatibility)}: @tab @code{subroutine acc_async_wait_all()} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.10. |
| @end table |
| |
| |
| |
| @node acc_wait_all_async |
| @section @code{acc_wait_all_async} -- Wait for completion of all asynchronous operations. |
| @table @asis |
| @item @emph{Description} |
| This function enqueues a wait operation on the queue @var{async} for any |
| and all asynchronous operations that have been previously enqueued on |
| any queue. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_wait_all_async(int async);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_wait_all_async(async)} |
| @item @tab @code{integer(acc_handle_kind) async} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.11. |
| @end table |
| |
| |
| |
| @node acc_wait_async |
| @section @code{acc_wait_async} -- Wait for completion of asynchronous operations. |
| @table @asis |
| @item @emph{Description} |
| This function enqueues a wait operation on queue @var{async} for any and all |
| asynchronous operations enqueued on queue @var{arg}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_wait_async(int arg, int async);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_wait_async(arg, async)} |
| @item @tab @code{integer(acc_handle_kind) arg, async} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.9. |
| @end table |
| |
| |
| |
| @node acc_init |
| @section @code{acc_init} -- Initialize runtime for a specific device type. |
| @table @asis |
| @item @emph{Description} |
| This function initializes the runtime for the device type specified in |
| @var{devicetype}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_init(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_init(devicetype)} |
| @item @tab @code{integer(acc_device_kind) devicetype} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.12. |
| @end table |
| |
| |
| |
| @node acc_shutdown |
| @section @code{acc_shutdown} -- Shuts down the runtime for a specific device type. |
| @table @asis |
| @item @emph{Description} |
| This function shuts down the runtime for the device type specified in |
| @var{devicetype}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_shutdown(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_shutdown(devicetype)} |
| @item @tab @code{integer(acc_device_kind) devicetype} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.13. |
| @end table |
| |
| |
| |
| @node acc_on_device |
| @section @code{acc_on_device} -- Whether executing on a particular device |
| @table @asis |
| @item @emph{Description}: |
| This function returns whether the program is executing on a particular |
| device specified in @var{devicetype}. In C/C++ a non-zero value is |
| returned to indicate the device is execiting on the specified device type. |
| In Fortran, @code{true} will be returned. If the program is not executing |
| on the specified device type C/C++ will return a zero, while Fortran will |
| return @code{false}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_on_device(acc_device_t devicetype);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_on_device(devicetype)} |
| @item @tab @code{integer(acc_device_kind) devicetype} |
| @item @tab @code{logical acc_on_device} |
| @end multitable |
| |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.14. |
| @end table |
| |
| |
| |
| @node acc_malloc |
| @section @code{acc_malloc} -- Allocate device memory. |
| @table @asis |
| @item @emph{Description} |
| This function allocates @var{len} bytes of device memory. It returns |
| the device address of the allocated memory. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{d_void* acc_malloc(size_t len);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.15. |
| @end table |
| |
| |
| |
| @node acc_free |
| @section @code{acc_free} -- Free device memory. |
| @table @asis |
| @item @emph{Description} |
| Free previously allocated device memory at the device address @code{a}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_free(d_void *a);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.16. |
| @end table |
| |
| |
| |
| @node acc_copyin |
| @section @code{acc_copyin} -- Allocate device memory and copy host memory to it. |
| @table @asis |
| @item @emph{Description} |
| In C/C++, this function allocates @var{len} bytes of device memory |
| and maps it to the specified host address in @var{a}. The device |
| address of the newly allocated device memory is returned. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a |
| variable or array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_copyin(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_copyin(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_copyin(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.17. |
| @end table |
| |
| |
| |
| @node acc_present_or_copyin |
| @section @code{acc_present_or_copyin} -- If the data is not present on the device, allocate device memory and copy from host memory. |
| @table @asis |
| @item @emph{Description} |
| This function tests if the host data specifed by @var{a} and of length |
| @var{len} is present or not. If it is not present, then device memory |
| will be allocated and the host memory copied. The device address of |
| the newly allocated device memory is returned. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_present_or_copyin(h_void *a, size_t len);} |
| @item @emph{Prototype}: @tab @code{void *acc_pcopyin(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_present_or_copyin(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_present_or_copyin(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @item @emph{Interface}: @tab @code{subroutine acc_pcopyin(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_pcopyin(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.18. |
| @end table |
| |
| |
| |
| @node acc_create |
| @section @code{acc_create} -- Allocate device memory and map it to host memory. |
| @table @asis |
| @item @emph{Description} |
| This function allocates device memory and maps it to host memory specified |
| by the host address @var{a} with a length of @var{len} bytes. In C/C++, |
| the function returns the device address of the allocated device memory. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_create(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_create(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_create(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.19. |
| @end table |
| |
| |
| |
| @node acc_present_or_create |
| @section @code{acc_present_or_create} -- If the data is not present on the device, allocate device memory and map it to host memory. |
| @table @asis |
| @item @emph{Description} |
| This function tests if the host data specifed by @var{a} and of length |
| @var{len} is present or not. If it is not present, then device memory |
| will be allocated and mapped to host memory. In C/C++, the device address |
| of the newly allocated device memory is returned. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_present_or_create(h_void *a, size_t len)} |
| @item @emph{Prototype}: @tab @code{void *acc_pcreate(h_void *a, size_t len)} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_present_or_create(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_present_or_create(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @item @emph{Interface}: @tab @code{subroutine acc_pcreate(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_pcreate(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.20. |
| @end table |
| |
| |
| |
| @node acc_copyout |
| @section @code{acc_copyout} -- Copy device memory to host memory. |
| @table @asis |
| @item @emph{Description} |
| This function copies mapped device memory to host memory which is specified |
| by host address @var{a} for a length @var{len} bytes in C/C++. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_copyout(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_copyout(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_copyout(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.21. |
| @end table |
| |
| |
| |
| @node acc_delete |
| @section @code{acc_delete} -- Free device memory. |
| @table @asis |
| @item @emph{Description} |
| This function frees previously allocated device memory specified by |
| the device address @var{a} and the length of @var{len} bytes. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_delete(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_delete(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_delete(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.22. |
| @end table |
| |
| |
| |
| @node acc_update_device |
| @section @code{acc_update_device} -- Update device memory from mapped host memory. |
| @table @asis |
| @item @emph{Description} |
| This function updates the device copy from the previously mapped host memory. |
| The host memory is specified with the host address @var{a} and a length of |
| @var{len} bytes. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_update_device(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_update_device(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_update_device(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.23. |
| @end table |
| |
| |
| |
| @node acc_update_self |
| @section @code{acc_update_self} -- Update host memory from mapped device memory. |
| @table @asis |
| @item @emph{Description} |
| This function updates the host copy from the previously mapped device memory. |
| The host memory is specified with the host address @var{a} and a length of |
| @var{len} bytes. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_update_self(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{subroutine acc_update_self(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @emph{Interface}: @tab @code{subroutine acc_update_self(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.24. |
| @end table |
| |
| |
| |
| @node acc_map_data |
| @section @code{acc_map_data} -- Map previously allocated device memory to host memory. |
| @table @asis |
| @item @emph{Description} |
| This function maps previously allocated device and host memory. The device |
| memory is specified with the device address @var{d}. The host memory is |
| specified with the host address @var{h} and a length of @var{len}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_map_data(h_void *h, d_void *d, size_t len);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.25. |
| @end table |
| |
| |
| |
| @node acc_unmap_data |
| @section @code{acc_unmap_data} -- Unmap device memory from host memory. |
| @table @asis |
| @item @emph{Description} |
| This function unmaps previously mapped device and host memory. The latter |
| specified by @var{h}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_unmap_data(h_void *h);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.26. |
| @end table |
| |
| |
| |
| @node acc_deviceptr |
| @section @code{acc_deviceptr} -- Get device pointer associated with specific host address. |
| @table @asis |
| @item @emph{Description} |
| This function returns the device address that has been mapped to the |
| host address specified by @var{h}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_deviceptr(h_void *h);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.27. |
| @end table |
| |
| |
| |
| @node acc_hostptr |
| @section @code{acc_hostptr} -- Get host pointer associated with specific device address. |
| @table @asis |
| @item @emph{Description} |
| This function returns the host address that has been mapped to the |
| device address specified by @var{d}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_hostptr(d_void *d);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.28. |
| @end table |
| |
| |
| |
| @node acc_is_present |
| @section @code{acc_is_present} -- Indicate whether host variable / array is present on device. |
| @table @asis |
| @item @emph{Description} |
| This function indicates whether the specified host address in @var{a} and a |
| length of @var{len} bytes is present on the device. In C/C++, a non-zero |
| value is returned to indicate the presence of the mapped memory on the |
| device. A zero is returned to indicate the memory is not mapped on the |
| device. |
| |
| In Fortran, two (2) forms are supported. In the first form, @var{a} specifies |
| a contiguous array section. The second form @var{a} specifies a variable or |
| array element and @var{len} specifies the length in bytes. If the host |
| memory is mapped to device memory, then a @code{true} is returned. Otherwise, |
| a @code{false} is return to indicate the mapped memory is not present. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{int acc_is_present(h_void *a, size_t len);} |
| @end multitable |
| |
| @item @emph{Fortran}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Interface}: @tab @code{function acc_is_present(a)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{logical acc_is_present} |
| @item @emph{Interface}: @tab @code{function acc_is_present(a, len)} |
| @item @tab @code{type, dimension(:[,:]...) :: a} |
| @item @tab @code{integer len} |
| @item @tab @code{logical acc_is_present} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.29. |
| @end table |
| |
| |
| |
| @node acc_memcpy_to_device |
| @section @code{acc_memcpy_to_device} -- Copy host memory to device memory. |
| @table @asis |
| @item @emph{Description} |
| This function copies host memory specified by host address of @var{src} to |
| device memory specified by the device address @var{dest} for a length of |
| @var{bytes} bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_memcpy_to_device(d_void *dest, h_void *src, size_t bytes);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.30. |
| @end table |
| |
| |
| |
| @node acc_memcpy_from_device |
| @section @code{acc_memcpy_from_device} -- Copy device memory to host memory. |
| @table @asis |
| @item @emph{Description} |
| This function copies host memory specified by host address of @var{src} from |
| device memory specified by the device address @var{dest} for a length of |
| @var{bytes} bytes. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_memcpy_from_device(d_void *dest, h_void *src, size_t bytes);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 3.2.31. |
| @end table |
| |
| |
| |
| @node acc_get_current_cuda_device |
| @section @code{acc_get_current_cuda_device} -- Get CUDA device handle. |
| @table @asis |
| @item @emph{Description} |
| This function returns the CUDA device handle. This handle is the same |
| as used by the CUDA Runtime or Driver API's. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{void *acc_get_current_cuda_device(void);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| A.2.1.1. |
| @end table |
| |
| |
| |
| @node acc_get_current_cuda_context |
| @section @code{acc_get_current_cuda_context} -- Get CUDA context handle. |
| @table @asis |
| @item @emph{Description} |
| This function returns the CUDA context handle. This handle is the same |
| as used by the CUDA Runtime or Driver API's. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_get_current_cuda_context(void);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| A.2.1.2. |
| @end table |
| |
| |
| |
| @node acc_get_cuda_stream |
| @section @code{acc_get_cuda_stream} -- Get CUDA stream handle. |
| @table @asis |
| @item @emph{Description} |
| This function returns the CUDA stream handle. This handle is the same |
| as used by the CUDA Runtime or Driver API's. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_get_cuda_stream(void);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| A.2.1.3. |
| @end table |
| |
| |
| |
| @node acc_set_cuda_stream |
| @section @code{acc_set_cuda_stream} -- Set CUDA stream handle. |
| @table @asis |
| @item @emph{Description} |
| This function associates the stream handle specified by @var{stream} with |
| the asynchronous value specified by @var{async}. |
| |
| @item @emph{C/C++}: |
| @multitable @columnfractions .20 .80 |
| @item @emph{Prototype}: @tab @code{acc_set_cuda_stream(int async void *stream);} |
| @end multitable |
| |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| A.2.1.4. |
| @end table |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c OpenACC Environment Variables |
| @c --------------------------------------------------------------------- |
| |
| @node OpenACC Environment Variables |
| @chapter OpenACC Environment Variables |
| |
| The variables @env{ACC_DEVICE_TYPE} and @env{ACC_DEVICE_NUM} |
| are defined by section 4 of the OpenACC specification in version 2.0. |
| The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes. |
| |
| @menu |
| * ACC_DEVICE_TYPE:: |
| * ACC_DEVICE_NUM:: |
| * GCC_ACC_NOTIFY:: |
| @end menu |
| |
| |
| |
| @node ACC_DEVICE_TYPE |
| @section @code{ACC_DEVICE_TYPE} |
| @table @asis |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 4.1. |
| @end table |
| |
| |
| |
| @node ACC_DEVICE_NUM |
| @section @code{ACC_DEVICE_NUM} |
| @table @asis |
| @item @emph{Reference}: |
| @uref{https://www.openacc.org, OpenACC specification v2.0}, section |
| 4.2. |
| @end table |
| |
| |
| |
| @node GCC_ACC_NOTIFY |
| @section @code{GCC_ACC_NOTIFY} |
| @table @asis |
| @item @emph{Description}: |
| Print debug information pertaining to the accelerator. |
| @end table |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c CUDA Streams Usage |
| @c --------------------------------------------------------------------- |
| |
| @node CUDA Streams Usage |
| @chapter CUDA Streams Usage |
| |
| This applies to the @code{nvptx} plugin only. |
| |
| The library provides elements that perform asynchronous movement of |
| data and asynchronous operation of computing constructs. This |
| asynchronous functionality is implemented by making use of CUDA |
| streams@footnote{See "Stream Management" in "CUDA Driver API", |
| TRM-06703-001, Version 5.5, for additional information}. |
| |
| The primary means by that the asychronous functionality is accessed |
| is through the use of those OpenACC directives which make use of the |
| @code{async} and @code{wait} clauses. When the @code{async} clause is |
| first used with a directive, it creates a CUDA stream. If an |
| @code{async-argument} is used with the @code{async} clause, then the |
| stream is associated with the specified @code{async-argument}. |
| |
| Following the creation of an association between a CUDA stream and the |
| @code{async-argument} of an @code{async} clause, both the @code{wait} |
| clause and the @code{wait} directive can be used. When either the |
| clause or directive is used after stream creation, it creates a |
| rendezvous point whereby execution waits until all operations |
| associated with the @code{async-argument}, that is, stream, have |
| completed. |
| |
| Normally, the management of the streams that are created as a result of |
| using the @code{async} clause, is done without any intervention by the |
| caller. This implies the association between the @code{async-argument} |
| and the CUDA stream will be maintained for the lifetime of the program. |
| However, this association can be changed through the use of the library |
| function @code{acc_set_cuda_stream}. When the function |
| @code{acc_set_cuda_stream} is called, the CUDA stream that was |
| originally associated with the @code{async} clause will be destroyed. |
| Caution should be taken when changing the association as subsequent |
| references to the @code{async-argument} refer to a different |
| CUDA stream. |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c OpenACC Library Interoperability |
| @c --------------------------------------------------------------------- |
| |
| @node OpenACC Library Interoperability |
| @chapter OpenACC Library Interoperability |
| |
| @section Introduction |
| |
| The OpenACC library uses the CUDA Driver API, and may interact with |
| programs that use the Runtime library directly, or another library |
| based on the Runtime library, e.g., CUBLAS@footnote{See section 2.26, |
| "Interactions with the CUDA Driver API" in |
| "CUDA Runtime API", Version 5.5, and section 2.27, "VDPAU |
| Interoperability", in "CUDA Driver API", TRM-06703-001, Version 5.5, |
| for additional information on library interoperability.}. |
| This chapter describes the use cases and what changes are |
| required in order to use both the OpenACC library and the CUBLAS and Runtime |
| libraries within a program. |
| |
| @section First invocation: NVIDIA CUBLAS library API |
| |
| In this first use case (see below), a function in the CUBLAS library is called |
| prior to any of the functions in the OpenACC library. More specifically, the |
| function @code{cublasCreate()}. |
| |
| When invoked, the function initializes the library and allocates the |
| hardware resources on the host and the device on behalf of the caller. Once |
| the initialization and allocation has completed, a handle is returned to the |
| caller. The OpenACC library also requires initialization and allocation of |
| hardware resources. Since the CUBLAS library has already allocated the |
| hardware resources for the device, all that is left to do is to initialize |
| the OpenACC library and acquire the hardware resources on the host. |
| |
| Prior to calling the OpenACC function that initializes the library and |
| allocate the host hardware resources, you need to acquire the device number |
| that was allocated during the call to @code{cublasCreate()}. The invoking of the |
| runtime library function @code{cudaGetDevice()} accomplishes this. Once |
| acquired, the device number is passed along with the device type as |
| parameters to the OpenACC library function @code{acc_set_device_num()}. |
| |
| Once the call to @code{acc_set_device_num()} has completed, the OpenACC |
| library uses the context that was created during the call to |
| @code{cublasCreate()}. In other words, both libraries will be sharing the |
| same context. |
| |
| @smallexample |
| /* Create the handle */ |
| s = cublasCreate(&h); |
| if (s != CUBLAS_STATUS_SUCCESS) |
| @{ |
| fprintf(stderr, "cublasCreate failed %d\n", s); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Get the device number */ |
| e = cudaGetDevice(&dev); |
| if (e != cudaSuccess) |
| @{ |
| fprintf(stderr, "cudaGetDevice failed %d\n", e); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Initialize OpenACC library and use device 'dev' */ |
| acc_set_device_num(dev, acc_device_nvidia); |
| |
| @end smallexample |
| @center Use Case 1 |
| |
| @section First invocation: OpenACC library API |
| |
| In this second use case (see below), a function in the OpenACC library is |
| called prior to any of the functions in the CUBLAS library. More specificially, |
| the function @code{acc_set_device_num()}. |
| |
| In the use case presented here, the function @code{acc_set_device_num()} |
| is used to both initialize the OpenACC library and allocate the hardware |
| resources on the host and the device. In the call to the function, the |
| call parameters specify which device to use and what device |
| type to use, i.e., @code{acc_device_nvidia}. It should be noted that this |
| is but one method to initialize the OpenACC library and allocate the |
| appropriate hardware resources. Other methods are available through the |
| use of environment variables and these will be discussed in the next section. |
| |
| Once the call to @code{acc_set_device_num()} has completed, other OpenACC |
| functions can be called as seen with multiple calls being made to |
| @code{acc_copyin()}. In addition, calls can be made to functions in the |
| CUBLAS library. In the use case a call to @code{cublasCreate()} is made |
| subsequent to the calls to @code{acc_copyin()}. |
| As seen in the previous use case, a call to @code{cublasCreate()} |
| initializes the CUBLAS library and allocates the hardware resources on the |
| host and the device. However, since the device has already been allocated, |
| @code{cublasCreate()} will only initialize the CUBLAS library and allocate |
| the appropriate hardware resources on the host. The context that was created |
| as part of the OpenACC initialization is shared with the CUBLAS library, |
| similarly to the first use case. |
| |
| @smallexample |
| dev = 0; |
| |
| acc_set_device_num(dev, acc_device_nvidia); |
| |
| /* Copy the first set to the device */ |
| d_X = acc_copyin(&h_X[0], N * sizeof (float)); |
| if (d_X == NULL) |
| @{ |
| fprintf(stderr, "copyin error h_X\n"); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Copy the second set to the device */ |
| d_Y = acc_copyin(&h_Y1[0], N * sizeof (float)); |
| if (d_Y == NULL) |
| @{ |
| fprintf(stderr, "copyin error h_Y1\n"); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Create the handle */ |
| s = cublasCreate(&h); |
| if (s != CUBLAS_STATUS_SUCCESS) |
| @{ |
| fprintf(stderr, "cublasCreate failed %d\n", s); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Perform saxpy using CUBLAS library function */ |
| s = cublasSaxpy(h, N, &alpha, d_X, 1, d_Y, 1); |
| if (s != CUBLAS_STATUS_SUCCESS) |
| @{ |
| fprintf(stderr, "cublasSaxpy failed %d\n", s); |
| exit(EXIT_FAILURE); |
| @} |
| |
| /* Copy the results from the device */ |
| acc_memcpy_from_device(&h_Y1[0], d_Y, N * sizeof (float)); |
| |
| @end smallexample |
| @center Use Case 2 |
| |
| @section OpenACC library and environment variables |
| |
| There are two environment variables associated with the OpenACC library |
| that may be used to control the device type and device number: |
| @env{ACC_DEVICE_TYPE} and @env{ACC_DEVICE_NUM}, respecively. These two |
| environement variables can be used as an alternative to calling |
| @code{acc_set_device_num()}. As seen in the second use case, the device |
| type and device number were specified using @code{acc_set_device_num()}. |
| If however, the aforementioned environment variables were set, then the |
| call to @code{acc_set_device_num()} would not be required. |
| |
| |
| The use of the environment variables is only relevant when an OpenACC function |
| is called prior to a call to @code{cudaCreate()}. If @code{cudaCreate()} |
| is called prior to a call to an OpenACC function, then you must call |
| @code{acc_set_device_num()}@footnote{More complete information |
| about @env{ACC_DEVICE_TYPE} and @env{ACC_DEVICE_NUM} can be found in |
| sections 4.1 and 4.2 of the @uref{https://www.openacc.org, OpenACC} |
| Application Programming Interface”, Version 2.0.} |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c The libgomp ABI |
| @c --------------------------------------------------------------------- |
| |
| @node The libgomp ABI |
| @chapter The libgomp ABI |
| |
| The following sections present notes on the external ABI as |
| presented by libgomp. Only maintainers should need them. |
| |
| @menu |
| * Implementing MASTER construct:: |
| * Implementing CRITICAL construct:: |
| * Implementing ATOMIC construct:: |
| * Implementing FLUSH construct:: |
| * Implementing BARRIER construct:: |
| * Implementing THREADPRIVATE construct:: |
| * Implementing PRIVATE clause:: |
| * Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses:: |
| * Implementing REDUCTION clause:: |
| * Implementing PARALLEL construct:: |
| * Implementing FOR construct:: |
| * Implementing ORDERED construct:: |
| * Implementing SECTIONS construct:: |
| * Implementing SINGLE construct:: |
| * Implementing OpenACC's PARALLEL construct:: |
| @end menu |
| |
| |
| @node Implementing MASTER construct |
| @section Implementing MASTER construct |
| |
| @smallexample |
| if (omp_get_thread_num () == 0) |
| block |
| @end smallexample |
| |
| Alternately, we generate two copies of the parallel subfunction |
| and only include this in the version run by the master thread. |
| Surely this is not worthwhile though... |
| |
| |
| |
| @node Implementing CRITICAL construct |
| @section Implementing CRITICAL construct |
| |
| Without a specified name, |
| |
| @smallexample |
| void GOMP_critical_start (void); |
| void GOMP_critical_end (void); |
| @end smallexample |
| |
| so that we don't get COPY relocations from libgomp to the main |
| application. |
| |
| With a specified name, use omp_set_lock and omp_unset_lock with |
| name being transformed into a variable declared like |
| |
| @smallexample |
| omp_lock_t gomp_critical_user_<name> __attribute__((common)) |
| @end smallexample |
| |
| Ideally the ABI would specify that all zero is a valid unlocked |
| state, and so we wouldn't need to initialize this at |
| startup. |
| |
| |
| |
| @node Implementing ATOMIC construct |
| @section Implementing ATOMIC construct |
| |
| The target should implement the @code{__sync} builtins. |
| |
| Failing that we could add |
| |
| @smallexample |
| void GOMP_atomic_enter (void) |
| void GOMP_atomic_exit (void) |
| @end smallexample |
| |
| which reuses the regular lock code, but with yet another lock |
| object private to the library. |
| |
| |
| |
| @node Implementing FLUSH construct |
| @section Implementing FLUSH construct |
| |
| Expands to the @code{__sync_synchronize} builtin. |
| |
| |
| |
| @node Implementing BARRIER construct |
| @section Implementing BARRIER construct |
| |
| @smallexample |
| void GOMP_barrier (void) |
| @end smallexample |
| |
| |
| @node Implementing THREADPRIVATE construct |
| @section Implementing THREADPRIVATE construct |
| |
| In _most_ cases we can map this directly to @code{__thread}. Except |
| that OMP allows constructors for C++ objects. We can either |
| refuse to support this (how often is it used?) or we can |
| implement something akin to .ctors. |
| |
| Even more ideally, this ctor feature is handled by extensions |
| to the main pthreads library. Failing that, we can have a set |
| of entry points to register ctor functions to be called. |
| |
| |
| |
| @node Implementing PRIVATE clause |
| @section Implementing PRIVATE clause |
| |
| In association with a PARALLEL, or within the lexical extent |
| of a PARALLEL block, the variable becomes a local variable in |
| the parallel subfunction. |
| |
| In association with FOR or SECTIONS blocks, create a new |
| automatic variable within the current function. This preserves |
| the semantic of new variable creation. |
| |
| |
| |
| @node Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses |
| @section Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses |
| |
| This seems simple enough for PARALLEL blocks. Create a private |
| struct for communicating between the parent and subfunction. |
| In the parent, copy in values for scalar and "small" structs; |
| copy in addresses for others TREE_ADDRESSABLE types. In the |
| subfunction, copy the value into the local variable. |
| |
| It is not clear what to do with bare FOR or SECTION blocks. |
| The only thing I can figure is that we do something like: |
| |
| @smallexample |
| #pragma omp for firstprivate(x) lastprivate(y) |
| for (int i = 0; i < n; ++i) |
| body; |
| @end smallexample |
| |
| which becomes |
| |
| @smallexample |
| @{ |
| int x = x, y; |
| |
| // for stuff |
| |
| if (i == n) |
| y = y; |
| @} |
| @end smallexample |
| |
| where the "x=x" and "y=y" assignments actually have different |
| uids for the two variables, i.e. not something you could write |
| directly in C. Presumably this only makes sense if the "outer" |
| x and y are global variables. |
| |
| COPYPRIVATE would work the same way, except the structure |
| broadcast would have to happen via SINGLE machinery instead. |
| |
| |
| |
| @node Implementing REDUCTION clause |
| @section Implementing REDUCTION clause |
| |
| The private struct mentioned in the previous section should have |
| a pointer to an array of the type of the variable, indexed by the |
| thread's @var{team_id}. The thread stores its final value into the |
| array, and after the barrier, the master thread iterates over the |
| array to collect the values. |
| |
| |
| @node Implementing PARALLEL construct |
| @section Implementing PARALLEL construct |
| |
| @smallexample |
| #pragma omp parallel |
| @{ |
| body; |
| @} |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| void subfunction (void *data) |
| @{ |
| use data; |
| body; |
| @} |
| |
| setup data; |
| GOMP_parallel_start (subfunction, &data, num_threads); |
| subfunction (&data); |
| GOMP_parallel_end (); |
| @end smallexample |
| |
| @smallexample |
| void GOMP_parallel_start (void (*fn)(void *), void *data, unsigned num_threads) |
| @end smallexample |
| |
| The @var{FN} argument is the subfunction to be run in parallel. |
| |
| The @var{DATA} argument is a pointer to a structure used to |
| communicate data in and out of the subfunction, as discussed |
| above with respect to FIRSTPRIVATE et al. |
| |
| The @var{NUM_THREADS} argument is 1 if an IF clause is present |
| and false, or the value of the NUM_THREADS clause, if |
| present, or 0. |
| |
| The function needs to create the appropriate number of |
| threads and/or launch them from the dock. It needs to |
| create the team structure and assign team ids. |
| |
| @smallexample |
| void GOMP_parallel_end (void) |
| @end smallexample |
| |
| Tears down the team and returns us to the previous @code{omp_in_parallel()} state. |
| |
| |
| |
| @node Implementing FOR construct |
| @section Implementing FOR construct |
| |
| @smallexample |
| #pragma omp parallel for |
| for (i = lb; i <= ub; i++) |
| body; |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| void subfunction (void *data) |
| @{ |
| long _s0, _e0; |
| while (GOMP_loop_static_next (&_s0, &_e0)) |
| @{ |
| long _e1 = _e0, i; |
| for (i = _s0; i < _e1; i++) |
| body; |
| @} |
| GOMP_loop_end_nowait (); |
| @} |
| |
| GOMP_parallel_loop_static (subfunction, NULL, 0, lb, ub+1, 1, 0); |
| subfunction (NULL); |
| GOMP_parallel_end (); |
| @end smallexample |
| |
| @smallexample |
| #pragma omp for schedule(runtime) |
| for (i = 0; i < n; i++) |
| body; |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| @{ |
| long i, _s0, _e0; |
| if (GOMP_loop_runtime_start (0, n, 1, &_s0, &_e0)) |
| do @{ |
| long _e1 = _e0; |
| for (i = _s0, i < _e0; i++) |
| body; |
| @} while (GOMP_loop_runtime_next (&_s0, _&e0)); |
| GOMP_loop_end (); |
| @} |
| @end smallexample |
| |
| Note that while it looks like there is trickiness to propagating |
| a non-constant STEP, there isn't really. We're explicitly allowed |
| to evaluate it as many times as we want, and any variables involved |
| should automatically be handled as PRIVATE or SHARED like any other |
| variables. So the expression should remain evaluable in the |
| subfunction. We can also pull it into a local variable if we like, |
| but since its supposed to remain unchanged, we can also not if we like. |
| |
| If we have SCHEDULE(STATIC), and no ORDERED, then we ought to be |
| able to get away with no work-sharing context at all, since we can |
| simply perform the arithmetic directly in each thread to divide up |
| the iterations. Which would mean that we wouldn't need to call any |
| of these routines. |
| |
| There are separate routines for handling loops with an ORDERED |
| clause. Bookkeeping for that is non-trivial... |
| |
| |
| |
| @node Implementing ORDERED construct |
| @section Implementing ORDERED construct |
| |
| @smallexample |
| void GOMP_ordered_start (void) |
| void GOMP_ordered_end (void) |
| @end smallexample |
| |
| |
| |
| @node Implementing SECTIONS construct |
| @section Implementing SECTIONS construct |
| |
| A block as |
| |
| @smallexample |
| #pragma omp sections |
| @{ |
| #pragma omp section |
| stmt1; |
| #pragma omp section |
| stmt2; |
| #pragma omp section |
| stmt3; |
| @} |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| for (i = GOMP_sections_start (3); i != 0; i = GOMP_sections_next ()) |
| switch (i) |
| @{ |
| case 1: |
| stmt1; |
| break; |
| case 2: |
| stmt2; |
| break; |
| case 3: |
| stmt3; |
| break; |
| @} |
| GOMP_barrier (); |
| @end smallexample |
| |
| |
| @node Implementing SINGLE construct |
| @section Implementing SINGLE construct |
| |
| A block like |
| |
| @smallexample |
| #pragma omp single |
| @{ |
| body; |
| @} |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| if (GOMP_single_start ()) |
| body; |
| GOMP_barrier (); |
| @end smallexample |
| |
| while |
| |
| @smallexample |
| #pragma omp single copyprivate(x) |
| body; |
| @end smallexample |
| |
| becomes |
| |
| @smallexample |
| datap = GOMP_single_copy_start (); |
| if (datap == NULL) |
| @{ |
| body; |
| data.x = x; |
| GOMP_single_copy_end (&data); |
| @} |
| else |
| x = datap->x; |
| GOMP_barrier (); |
| @end smallexample |
| |
| |
| |
| @node Implementing OpenACC's PARALLEL construct |
| @section Implementing OpenACC's PARALLEL construct |
| |
| @smallexample |
| void GOACC_parallel () |
| @end smallexample |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Reporting Bugs |
| @c --------------------------------------------------------------------- |
| |
| @node Reporting Bugs |
| @chapter Reporting Bugs |
| |
| Bugs in the GNU Offloading and Multi Processing Runtime Library should |
| be reported via @uref{http://gcc.gnu.org/bugzilla/, Bugzilla}. Please add |
| "openacc", or "openmp", or both to the keywords field in the bug |
| report, as appropriate. |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c GNU General Public License |
| @c --------------------------------------------------------------------- |
| |
| @include gpl_v3.texi |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c GNU Free Documentation License |
| @c --------------------------------------------------------------------- |
| |
| @include fdl.texi |
| |
| |
| |
| @c --------------------------------------------------------------------- |
| @c Funding Free Software |
| @c --------------------------------------------------------------------- |
| |
| @include funding.texi |
| |
| @c --------------------------------------------------------------------- |
| @c Index |
| @c --------------------------------------------------------------------- |
| |
| @node Library Index |
| @unnumbered Library Index |
| |
| @printindex cp |
| |
| @bye |