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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 -	program	assertion (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  op-
       eration.	 The value zero	is always correct.  Other assertion values may
       be or'ed	together.  Assertions that 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 com-
       municators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_er-
       rhandler	(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 guarantee that an MPI program can continue past
       an error; however, MPI implementations will attempt to  continue	 when-
       ever possible.

       MPI_SUCCESS
	      -	No error; MPI routine completed	successfully.
       MPI_ERR_GROUP
	      -	Null or	invalid	group passed to	function.
       MPI_ERR_WIN
	      -	Invalid	MPI window object
       MPI_ERR_OTHER
	      -	 Other	error;	use  MPI_Error_string  to get more information
	      about this error code.

				   2/3/2025		      MPI_Win_start(3)

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