Ubuntu Manpage: MPI_Win_create - Create an MPI Window object for one-sided communication

name
synopsis
input parameters
output parameters
notes
thread and interrupt safety
notes for fortran
errors
see also

NAME

       MPI_Win_create -  Create an MPI Window object for one-sided communication

SYNOPSIS

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

       This is a collective call executed by all processes in the group of comm. It returns a window object that
       can be used by these processes to perform RMA operations. Each process specifies  a  window  of  existing
       memory that it exposes to RMA accesses by the processes in the group of comm. The window consists of size
       bytes, starting at address base. In C, base is the starting address of a memory region. In  Fortran,  one
       can  pass  the  first element of a memory region or a whole array, which must be 'simply contiguous' (for
       'simply contiguous', see also MPI 3.0, Section 17.1.12 on page 626). A process may  elect  to  expose  no
       memory by specifying size = 0.

INPUT PARAMETERS

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

OUTPUT PARAMETERS

       win    - window object returned by the call (handle)

NOTES

The displacement unit argument is provided to facilitate address arithmetic in RMA operations: the target
displacement argument of an RMA operation 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 predefined.

no_locks
- If set to true, then the implementation may assume that passive 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 activity 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 implementation
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 operation
types where the hardware can guarantee atomicity. The default is same_op_no_op.

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