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MPI_Win_start(3)                      MPI                     MPI_Win_start(3)


NAME

       MPI_Win_start -  Start an RMA access epoch for MPI


SYNOPSIS

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


INPUT PARAMETERS

       group  - group of target processes (handle)
       assert - Used to optimize this call; zero may be used as a default.
              See notes. (integer)
       win    - window object (handle)


NOTES

       The assert argument is used to indicate special conditions for the
       fence that an implementation may use to optimize the MPI_Win_start
       operation.  The value zero is always correct.  Other assertion values
       may be or'ed together.  Assertions tha are valid for MPI_Win_start are:

       MPI_MODE_NOCHECK
              - the matching calls to MPI_WIN_POST have already completed on
              all target processes when the call to MPI_WIN_START is made.
              The nocheck option can be specified in a start call if and only
              if it is specified in each matching post call. This is similar
              to the optimization of ready-send that may save a handshake when
              the handshake is implicit in the code. (However, ready-send is
              matched by a regular receive, whereas both start and post must
              specify the nocheck option.)


THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be
       safely used by multiple threads without the need for any user-provided
       thread locks.  However, the routine is not interrupt safe.  Typically,
       this is due to the use of memory allocation routines such as malloc or
       other non-MPICH runtime routines that are themselves not interrupt-
       safe.


NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
       an additional argument ierr at the end of the argument list.  ierr is
       an integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are invoked with
       the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
       Fortran.


ERRORS

       All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
       value; C routines as the value of the function and Fortran routines in
       the last argument.  Before the value is returned, the current MPI error
       handler is called.  By default, this error handler aborts the MPI job.
       The error handler may be changed with MPI_Comm_set_errhandler (for
       communicators), MPI_File_set_errhandler (for files), and
       MPI_Win_set_errhandler (for RMA windows).  The MPI-1 routine
       MPI_Errhandler_set may be used but its use is deprecated.  The
       predefined error handler MPI_ERRORS_RETURN may be used to cause error
       values to be returned.  Note that MPI does not guarentee that an MPI
       program can continue past an error; however, MPI implementations will
       attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_WIN
              - Invalid MPI window object
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information
              about this error code.


LOCATION

       src/mpi/rma/win_start.c

                                   9/20/2012                  MPI_Win_start(3)

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