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MPI_Win_start.3.rst

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MPI_Win_start

:ref:`MPI_Win_start` |mdash| Starts an RMA access epoch for win

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Win_start(MPI_Group group, int assert, MPI_Win win)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WIN_START(GROUP, ASSERT, WIN, IERROR)
     INTEGER GROUP, ASSERT, WIN, IERROR

Fortran 2008 Syntax

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

.. seealso::
   * :ref:`MPI_Win_post`
   * :ref:`MPI_Win_complete`