


MPI_Win_create(3)            LAM/MPI            MPI_Win_create(3)


NAME
       MPI_Win_create -  Specifies an window accessible by remote processes

SYNOPSIS
       #include <mpi.h>
       int
       MPI_Win_create(void *base, MPI_Aint size, int disp_unit,
               MPI_Info info, MPI_Comm comm, MPI_Win *newwin)

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)
       newwin - window object returned by the call (handle)


NOTES
       Common choices for disp_unit are 1 (no  scaling),  and  (in  C  syntax)
       sizeof(type),  for  a  window  that consists of an array of elements of
       type type. The later choice will allow one to use array indices in  RMA
       calls, and have those scaled correctly to byte displacements, even in a
       heterogeneous environment. ( End of advice to users.)  The  info  argu-
       ment  provides  optimization  hints  to  the runtime about the expected
       usage pattern of the window.

       The various processes in the group of comm may specify completely  dif-
       ferent  target  windows, in location, size, displacement units and info
       arguments. As long as all the get, put and  accumulate  accesses  to  a
       particular process fit their specific target window this should pose no
       problem. The same area in memory may appear in multiple  windows,  each
       associated with a different window object. However, concurrent communi-
       cations to distinct, overlapping windows may lead to erroneous results.


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.

USAGE WITH IMPI EXTENSIONS
       The IMPI standard only supports MPI-1 functions.  Hence, this  function
       is currently not designed to operate within an IMPI job.


ERRORS
       If an error occurs in an MPI function, the current MPI error handler is



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MPI_Win_create(3)            LAM/MPI            MPI_Win_create(3)


       called to handle it.  By default, this error  handler  aborts  the  MPI
       job.   The  error  handler may be changed with MPI_Errhandler_set ; the
       predefined error handler MPI_ERRORS_RETURN may be used to  cause  error
       values  to  be  returned  (in C and Fortran; this error handler is less
       useful in with the C++ MPI  bindings.   The  predefined  error  handler
       MPI::ERRORS_THROW_EXCEPTIONS  should  be used in C++ if the error value
       needs to be recovered).  Note that MPI does not guarantee that  an  MPI
       program can continue past an error.

       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.  The C++ bindings for MPI do not return error val-
       ues; instead, error values are communicated by throwing  exceptions  of
       type  MPI::Exception  (but not by default).  Exceptions are only thrown
       if the error value is not MPI::SUCCESS
        .

       Note that if the MPI::ERRORS_RETURN handler is set in  C++,  while  MPI
       functions  will  return  upon an error, there will be no way to recover
       what the actual error value was.
       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       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_ARG
              - Invalid argument.  Some argument is invalid and is not identi-
              fied by a specific  error  class.   This  is  typically  a  NULL
              pointer or other such error.
       MPI_ERR_OTHER
              -  Other  error;  use  MPI_Error_string  to get more information
              about this error code.
       MPI_ERR_INTERN
              - An internal error has been detected.  This is  fatal.   Please
              send  a  bug report to the LAM mailing list (see http://www.lam-
              mpi.org/contact.php ).


SEE ALSO
       MPI_Put(3),    MPI_Get(3),     MPI_Accumulate(3),     MPI_Win_start(3),
       MPI_Win_complete(3),         MPI_Win_fence(3),         MPI_Win_free(3),
       MPI_Win_get_group(3), MPI_Win_get_group(3), MPI_Win_wait(3)


MORE INFORMATION
       For more information, please see the official MPI Forum web site, which
       contains  the  text of both the MPI-1 and MPI-2 standards.  These docu-
       ments contain detailed information about each  MPI  function  (most  of
       which is not duplicated in these man pages).

       http://www.mpi-forum.org/

LOCATION
       wcreate.c



LAM/MPI 6.5.9               1/27/2003                           2


