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 oper-
       ation.  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

       win_start.c

								     5/20/2010							  MPI_Win_start(3)