DragonFly On-Line Manual Pages
MPI_Graph_create(3) MPI MPI_Graph_create(3)
MPI_Graph_create - Makes a new communicator to which topology
information has been attached
int MPI_Graph_create(MPI_Comm comm_old, int nnodes, MPICH2_CONST int *indx,
MPICH2_CONST int *edges, int reorder, MPI_Comm *comm_graph)
- input communicator without topology (handle)
nnodes - number of nodes in graph (integer)
indx - array of integers describing node degrees (see below)
edges - array of integers describing graph edges (see below)
- ranking may be reordered (true) or not (false) (logical)
- communicator with graph topology added (handle)
Each process must provide a description of the entire graph, not just
the neigbors of the calling process.
We ignore the reorder info currently.
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 topology. Either there is no topology associated with
this communicator, or it is not the correct type (e.g., MPI_CART
when expecting MPI_GRAPH ).
- 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 (e.g., MPI_ERR_RANK ).