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openmpi/ompi/mca/topo/example/topo_example_cart_map.c
2016-11-22 15:03:20 -08:00

80 строки
2.5 KiB
C

/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2013 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2009 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2012-2013 Inria. All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "ompi_config.h"
#include "ompi/mca/topo/example/topo_example.h"
#include "ompi/communicator/communicator.h"
/*
* function - mca_topo_example_cart_map
*
* @param comm input communicator (handle)
* @param ndims number of dimensions of cartesian structure (integer)
* @param dims integer array of size 'ndims' specifying the number of
* processes in each coordinate direction
* @param periods logical array of size 'ndims' specifying the
* periodicity specification in each coordinate direction
* @param newrank reordered rank of the calling process; 'MPI_UNDEFINED'
* if calling process does not belong to grid (integer)
*
* @retval MPI_SUCCESS
* @retval MPI_ERR_DIMS
*/
int mca_topo_example_cart_map (ompi_communicator_t* comm,
int ndims,
int *dims,
int *periods,
int *newrank)
{
int nprocs;
int rank;
int size;
int i;
int *p;
/*
* Compute the # of processes in the grid.
*/
nprocs = 1;
for (i = 0, p = dims; i < ndims; ++i, ++p) {
if (*p <= 0) {
return MPI_ERR_DIMS;
}
nprocs *= *p;
}
/*
* Check that number of processes <= size of communicator.
*/
size = ompi_comm_size(comm);
if (nprocs > size) {
return MPI_ERR_DIMS;
}
/*
* Compute my new rank. To be slightly different than the "unity"
* component, start with a rank that is size-my_initial_rank.
*/
rank = ompi_comm_size(comm) - 1 - ompi_comm_rank(comm);
*newrank = ((rank < 0) || (rank >= nprocs)) ? MPI_UNDEFINED : rank;
return MPI_SUCCESS;
}