MPI_Win_create - Specifies an window accessible by remote processes
MPI_Win_create(void *base, MPI_Aint size, int disp_unit,
MPI_Info info, MPI_Comm comm, MPI_Win *newwin)
base - initial address of window (choice)
size - size of window in bytes (nonnegative integer)
- local unit size for displacements, in bytes (positive integer)
info - info argument (handle)
comm - communicator (handle)
newwin - window object returned by the call (handle)
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
argument 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
different 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
communications to distinct, overlapping windows may lead to erroneous
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
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.
If an error occurs in an MPI function, the current MPI error handler is
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
values; 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.
- No error; MPI routine completed successfully.
- Invalid communicator. A common error is to use a null
communicator in a call (not even allowed in MPI_Comm_rank ).
- Invalid argument. Some argument is invalid and is not
identified by a specific error class. This is typically a NULL
pointer or other such error.
- Other error; use MPI_Error_string to get more information
about this error code.
- An internal error has been detected. This is fatal. Please
send a bug report to the LAM mailing list (see http://www.lam-
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)
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
documents contain detailed information about each MPI function (most of
which is not duplicated in these man pages).