NAME

       MPI_Win_start - 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

C++ Syntax

       #include <mpi.h>
       void MPI::Win::Start(const MPI::Group& group, int assert) const

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

       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 MPI_Win_post.
       MPI_Win_start is allowed to block until the corresponding  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

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran routines in the last argument. C++ functions do not return errors. If the  default
       error  handler  is  set  to  MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception
       mechanism will be used to throw an MPI::Exception object.

       Before the error value is returned, the current MPI error handler is called.  By  default,
       this  error  handler aborts the MPI job, except for I/O function errors. The error handler
       may be changed with MPI_Win_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may be used to cause error values to be returned. Note that MPI does not guarantee that an
       MPI program can continue past an error.

SEE ALSO

       MPI_Win_post MPI_Win_complete