DragonFly On-Line Manual Pages
MPI_Win_start(3) MPI MPI_Win_start(3)
MPI_Win_start - Start an RMA access epoch for MPI
int MPI_Win_start(MPI_Group group, int assert, MPI_Win win)
group - group of target processes (handle)
assert - Used to optimize this call; zero may be used as a default.
See notes. (integer)
win - window object (handle)
The assert argument is used to indicate special conditions for the
fence that an implementation may use to optimize the MPI_Win_start
operation. The value zero is always correct. Other assertion values
may be or'ed together. Assertions tha are valid for MPI_Win_start are:
- 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-
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
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.
- No error; MPI routine completed successfully.
- Invalid MPI window object
- Other error; use MPI_Error_string to get more information
about this error code.