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.. _mpi_win_start:
MPI_Win_start
=============
.. include_body
:ref:`MPI_Win_start` |mdash| Starts an RMA access epoch for *win*
SYNTAX
------
C Syntax
^^^^^^^^
.. code-block:: c
#include <mpi.h>
int MPI_Win_start(MPI_Group group, int assert, MPI_Win win)
Fortran Syntax
^^^^^^^^^^^^^^
.. code-block:: fortran
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WIN_START(GROUP, ASSERT, WIN, IERROR)
INTEGER GROUP, ASSERT, WIN, IERROR
Fortran 2008 Syntax
^^^^^^^^^^^^^^^^^^^
.. code-block:: fortran
USE mpi_f08
MPI_Win_start(group, assert, win, ierror)
TYPE(MPI_Group), INTENT(IN) :: group
INTEGER, INTENT(IN) :: assert
TYPE(MPI_Win), INTENT(IN) :: win
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
INPUT PARAMETERS
----------------
* ``group``: The group of target processes (handle).
* ``assert``: Program assertion (integer).
* ``win``: Window object (handle).
OUTPUT PARAMETERS
-----------------
* ``ierror``: Fortran only: Error status (integer).
DESCRIPTION
-----------
:ref:`MPI_Win_start` is a one-sided MPI communication synchronization call that
starts an RMA access epoch for *win*. RMA calls issued on *win* during
this epoch must access only windows at processes in *group*. Each
process in *group* must issue a matching call to :ref:`MPI_Win_post`.
:ref:`MPI_Win_start` is allowed to block until the corresponding :ref:`MPI_Win_post`
calls have been executed, but is not required to.
The *assert* argument is used to provide assertions on the context of
the call that may be used for various optimizations. (See Section 6.4.4
of the MPI-2 Standard.) A value of *assert* = 0 is always valid. The
following assertion value is supported:
MPI_MODE_NOCHECK
When this value is passed in to this call, the library assumes that
the post call on the target has been called and it is not necessary
for the library to check to see if such a call has been made.
ERRORS
------
.. include:: ./ERRORS.rst
.. seealso::
* :ref:`MPI_Win_post`
* :ref:`MPI_Win_complete`
|
