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/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
* 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) 2008 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2012-2013 Inria. All rights reserved.
* Copyright (c) 2014 Los Alamos National Security, LLC. All rights
* reserved.
* Copyright (c) 2014-2015 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "ompi_config.h"
#include "ompi/mca/topo/base/base.h"
#include "ompi/communicator/communicator.h"
/*
* function - partitions a communicator into subgroups which
* form lower-dimensional cartesian subgrids
*
* @param comm communicator with cartesian structure (handle)
* @param remain_dims the 'i'th entry of 'remain_dims' specifies whether
* the 'i'th dimension is kept in the subgrid (true)
* or is dropped (false) (logical vector)
* @param new_comm communicator containing the subgrid that includes the
* calling process (handle)
*
* @retval MPI_SUCCESS
* @retval MPI_ERR_TOPOLOGY
* @retval MPI_ERR_COMM
*/
int mca_topo_base_cart_sub (ompi_communicator_t* comm,
const int *remain_dims,
ompi_communicator_t** new_comm)
{
struct ompi_communicator_t *temp_comm;
mca_topo_base_comm_cart_2_2_0_t *old_cart;
int errcode, colour, key, colfactor, keyfactor;
int ndim, dim, i;
int *d, *dorig = NULL, *dold, *c, *p, *porig = NULL, *pold;
mca_topo_base_module_t* topo;
mca_topo_base_comm_cart_2_2_0_t* cart;
*new_comm = MPI_COMM_NULL;
old_cart = comm->c_topo->mtc.cart;
/*
* Compute colour and key used in splitting the communicator.
*/
colour = key = 0;
colfactor = keyfactor = 1;
ndim = 0;
i = old_cart->ndims - 1;
d = old_cart->dims + i;
c = comm->c_topo->mtc.cart->coords + i;
for (; i >= 0; --i, --d, --c) {
dim = *d;
if (remain_dims[i] == 0) {
colour += colfactor * (*c);
colfactor *= dim;
} else {
++ndim;
key += keyfactor * (*c);
keyfactor *= dim;
}
}
/* Special case: if all of remain_dims were false, we need to make
a 0-dimension cartesian communicator with just ourselves in it
(you can't have a communicator unless you're in it). */
if (0 == ndim) {
colour = ompi_comm_rank (comm);
}
/* Split the communicator. */
errcode = ompi_comm_split(comm, colour, key, &temp_comm, false);
if (errcode != OMPI_SUCCESS) {
return errcode;
}
/* Fill the communicator with topology information. */
if (temp_comm != MPI_COMM_NULL) {
assert( NULL == temp_comm->c_topo );
if (OMPI_SUCCESS != (errcode = mca_topo_base_comm_select(temp_comm,
comm->c_topo,
&topo,
OMPI_COMM_CART))) {
ompi_comm_free(&temp_comm);
return OMPI_ERR_OUT_OF_RESOURCE;
}
if (ndim >= 1) {
/* Copy the dimensions */
dorig = d = (int*)malloc(ndim * sizeof(int));
dold = old_cart->dims;
/* Copy the periods */
porig = p = (int*)malloc(ndim * sizeof(int));
pold = old_cart->periods;
for (i = 0; i < old_cart->ndims; ++i, ++dold, ++pold) {
if (remain_dims[i]) {
*d++ = *dold;
*p++ = *pold;
}
}
}
cart = OBJ_NEW(mca_topo_base_comm_cart_2_2_0_t);
if( NULL == cart ) {
ompi_comm_free(&temp_comm);
if (NULL != dorig) {
free(dorig);
}
if (NULL != porig) {
free(porig);
}
return OMPI_ERR_OUT_OF_RESOURCE;
}
cart->ndims = ndim;
cart->dims = dorig;
cart->periods = porig;
/* NTH: protect against a 0-byte alloc in the ndims = 0 case */
if (ndim > 0) {
cart->coords = (int*)malloc(sizeof(int) * ndim);
if (NULL == cart->coords) {
free(cart->periods);
if(NULL != cart->dims) free(cart->dims);
OBJ_RELEASE(cart);
return OMPI_ERR_OUT_OF_RESOURCE;
}
{ /* setup the cartesian topology */
int nprocs = temp_comm->c_local_group->grp_proc_count,
rank = temp_comm->c_local_group->grp_my_rank;
for (i = 0; i < ndim; ++i) {
nprocs /= cart->dims[i];
cart->coords[i] = rank / nprocs;
rank %= nprocs;
}
}
}
temp_comm->c_topo = topo;
temp_comm->c_topo->mtc.cart = cart;
temp_comm->c_topo->reorder = false;
temp_comm->c_flags |= OMPI_COMM_CART;
}
*new_comm = temp_comm;
return MPI_SUCCESS;
}
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