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MPI_Win_create(3)		      MPI		     MPI_Win_create(3)

NAME
       MPI_Win_create  -  Create an MPI	Window object for one-sided communica-
       tion

SYNOPSIS
       int MPI_Win_create(void *base, MPI_Aint size, int disp_unit, MPI_Info info,
       MPI_Comm	comm, MPI_Win *win)

       int MPI_Win_create_c(void *base,	MPI_Aint size, MPI_Aint	disp_unit,
       MPI_Info	info, MPI_Comm comm, MPI_Win *win)

INPUT PARAMETERS
       base   -	initial	address	of window (choice)
       size   -	size of	window in bytes	(non-negative integer)
       disp_unit
	      -	local unit size	for displacements, in bytes (positive integer)
       info   -	info argument (handle)
       comm   -	intra-communicator (handle)

OUTPUT PARAMETERS
       win    -	window object (handle)

NOTES
       The displacement	unit argument is provided to facilitate	address	arith-
       metic in	RMA operations:	the target displacement	argument of an RMA op-
       eration is scaled by the	 factor	 disp_unit  specified  by  the	target
       process,	at window creation.

       The  info argument provides optimization	hints to the runtime about the
       expected	usage pattern of the window. The following info	keys are  pre-
       defined.

       no_locks
	      -	 If  set to true, then the implementation may assume that pas-
	      sive    target	synchronization	   (i.e.,    MPI_Win_lock    ,
	      MPI_Win_lock_all	)  will	 not be	used on	the given window. This
	      implies that this	window is not used for 3-party	communication,
	      and RMA can be implemented with no (less)	asynchronous agent ac-
	      tivity at	this process.

       accumulate_ordering
	      -	 Controls the ordering of accumulate operations	at the target.
	      The argument string should contain a comma-separated list	of the
	      following	read/write ordering  rules,  where  e.g.  "raw"	 means
	      read-after-write:	"rar,raw,war,waw".

       accumulate_ops
	      -	 If  set  to  same_op, the implementation will assume that all
	      concurrent accumulate calls to the same target address will  use
	      the  same	operation. If set to same_op_no_op, then the implemen-
	      tation will assume that all concurrent accumulate	calls  to  the
	      same  target  address will use the same operation	or MPI_NO_OP .
	      This can eliminate the need to protect access for	certain	opera-
	      tion types where the hardware can	guarantee atomicity.  The  de-
	      fault is same_op_no_op.

       mpi_accumulate_granularity
	      -	 Controls  the desired synchronization granularity for accumu-
	      late ops.	It sets	the size of memory range in  bytes  for	 which
	      the  MPI	library	 should	acquire	a synchronization primitive to
	      ensure the atomicity of updates. The default is 0	which let  the
	      MPI  library decides the granularity.  When the info hint	is set
	      to a positive value,  the	 actual	 range	of  synchroniation  is
	      round-up to the next size	that fits the Datatype used in the ac-
	      cumulate	operation (see MPI standard 4.1). All processes	in the
	      group of a windows must set to the same value.

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_ARG
	      -	Invalid	argument.  Some	argument is invalid and	is not identi-
	      fied by a	specific error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_COMM
	      -	Invalid	communicator.  A common	error is to use	a null	commu-
	      nicator in a call	(not even allowed in MPI_Comm_rank ).
       MPI_ERR_DISP
	      -
       MPI_ERR_INFO
	      -	Invalid	Info
       MPI_ERR_SIZE
	      -
       MPI_ERR_OTHER
	      -	 Other	error;	use  MPI_Error_string  to get more information
	      about this error code.

SEE ALSO
       MPI_Win_allocate	    MPI_Win_allocate_shared	MPI_Win_create_dynamic
       MPI_Win_free

				   2/3/2025		     MPI_Win_create(3)

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