MPI_Graph_create(3) MPI MPI_Graph_create(3)NAMEMPI_Graph_create - Makes a new communicator to which topology informa‐
tion has been attached
SYNOPSIS
int MPI_Graph_create(MPI_Comm comm_old, int nnodes, const int indx[],
const int edges[], int reorder, MPI_Comm *comm_graph)
INPUT PARAMETERS
comm_old
- 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)
reorder
- ranking may be reordered (true) or not (false) (logical)
OUTPUT PARAMETERS
comm_graph
- communicator with graph topology added (handle)
NOTES
Each process must provide a description of the entire graph, not just
the neigbors of the calling process.
ALGORITHM
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-
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 com‐
municators), 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 prede‐
fined 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_TOPOLOGY
- 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 ).
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 (e.g., MPI_ERR_RANK ).
LOCATION
src/mpi/topo/graphcreate.c
8/22/2013 MPI_Graph_create(3)