[thirdparty/gcc.git] / libgomp / doc / openmp-environment-variables / ompprocbind.rst

..
  Copyright 1988-2022 Free Software Foundation, Inc.
  This is part of the GCC manual.
  For copying conditions, see the copyright.rst file.

.. index:: Environment Variable

.. _omp_proc_bind:

OMP_PROC_BIND -- Whether theads may be moved between CPUs
*********************************************************

Description:
  Specifies whether threads may be moved between processors.  If set to
  ``TRUE``, OpenMP theads should not be moved; if set to ``FALSE``
  they may be moved.  Alternatively, a comma separated list with the
  values ``PRIMARY``, ``MASTER``, ``CLOSE`` and ``SPREAD`` can
  be used to specify the thread affinity policy for the corresponding nesting
  level.  With ``PRIMARY`` and ``MASTER`` the worker threads are in the
  same place partition as the primary thread.  With ``CLOSE`` those are
  kept close to the primary thread in contiguous place partitions.  And
  with ``SPREAD`` a sparse distribution
  across the place partitions is used.  Specifying more than one item in the
  list will automatically enable nesting by default.

  When undefined, :envvar:`OMP_PROC_BIND` defaults to ``TRUE`` when
  :envvar:`OMP_PLACES` or :envvar:`GOMP_CPU_AFFINITY` is set and ``FALSE`` otherwise.

See also:
  :ref:`omp_get_proc_bind`, :ref:`GOMP_CPU_AFFINITY`,
  :ref:`OMP_NESTED`, :ref:`OMP_PLACES`

Reference:
  :openmp:`4.5`, Section 4.4
Commit	Line	Data
c63539ff ML	1	..
	2	Copyright 1988-2022 Free Software Foundation, Inc.
	3	This is part of the GCC manual.
	4	For copying conditions, see the copyright.rst file.
	5
	6	.. index:: Environment Variable
	7
	8	.. _omp_proc_bind:
	9
	10	OMP_PROC_BIND -- Whether theads may be moved between CPUs
	11	*********************************************************
	12
	13	Description:
	14	Specifies whether threads may be moved between processors. If set to
	15	``TRUE``, OpenMP theads should not be moved; if set to ``FALSE``
	16	they may be moved. Alternatively, a comma separated list with the
	17	values ``PRIMARY``, ``MASTER``, ``CLOSE`` and ``SPREAD`` can
	18	be used to specify the thread affinity policy for the corresponding nesting
	19	level. With ``PRIMARY`` and ``MASTER`` the worker threads are in the
	20	same place partition as the primary thread. With ``CLOSE`` those are
	21	kept close to the primary thread in contiguous place partitions. And
	22	with ``SPREAD`` a sparse distribution
	23	across the place partitions is used. Specifying more than one item in the
	24	list will automatically enable nesting by default.
	25
	26	When undefined, :envvar:`OMP_PROC_BIND` defaults to ``TRUE`` when
	27	:envvar:`OMP_PLACES` or :envvar:`GOMP_CPU_AFFINITY` is set and ``FALSE`` otherwise.
	28
	29	See also:
	30	:ref:`omp_get_proc_bind`, :ref:`GOMP_CPU_AFFINITY`,
	31	:ref:`OMP_NESTED`, :ref:`OMP_PLACES`
	32
	33	Reference:
3ed1b4ce	34	:openmp:`4.5`, Section 4.4