void Partitioner::repartition (MeshBase & mesh,
const unsigned int n)
{
// we cannot partition into more pieces than we have
// active elements!
const unsigned int n_parts =
static_cast<unsigned int>
(std::min(mesh.n_active_elem(), static_cast<dof_id_type>(n)));
// Set the number of partitions in the mesh
mesh.set_n_partitions()=n_parts;
if (n_parts == 1)
{
this->single_partition (mesh);
return;
}
// First assign a temporary partitioning to any unpartitioned elements
Partitioner::partition_unpartitioned_elements(mesh, n_parts);
// Call the partitioning function
this->_do_repartition(mesh,n_parts);
// Set the parent's processor ids
Partitioner::set_parent_processor_ids(mesh);
// Set the node's processor ids
Partitioner::set_node_processor_ids(mesh);
}
void Partitioner::partition (MeshBase & mesh,
const unsigned int n)
{
libmesh_parallel_only(mesh.comm());
// BSK - temporary fix while redistribution is integrated 6/26/2008
// Uncomment this to not repartition in parallel
// if (!mesh.is_serial())
// return;
// we cannot partition into more pieces than we have
// active elements!
const unsigned int n_parts =
static_cast<unsigned int>
(std::min(mesh.n_active_elem(), static_cast<dof_id_type>(n)));
// Set the number of partitions in the mesh
mesh.set_n_partitions()=n_parts;
if (n_parts == 1)
{
this->single_partition (mesh);
return;
}
// First assign a temporary partitioning to any unpartitioned elements
Partitioner::partition_unpartitioned_elements(mesh, n_parts);
// Call the partitioning function
this->_do_partition(mesh,n_parts);
// Set the parent's processor ids
Partitioner::set_parent_processor_ids(mesh);
// Redistribute elements if necessary, before setting node processor
// ids, to make sure those will be set consistently
mesh.redistribute();
#ifdef DEBUG
MeshTools::libmesh_assert_valid_remote_elems(mesh);
// Messed up elem processor_id()s can leave us without the child
// elements we need to restrict vectors on a distributed mesh
MeshTools::libmesh_assert_valid_procids<Elem>(mesh);
#endif
// Set the node's processor ids
Partitioner::set_node_processor_ids(mesh);
#ifdef DEBUG
MeshTools::libmesh_assert_valid_procids<Elem>(mesh);
#endif
// Give derived Mesh classes a chance to update any cached data to
// reflect the new partitioning
mesh.update_post_partitioning();
}
// ------------------------------------------------------------
// LinearPartitioner implementation
void LinearPartitioner::_do_partition (MeshBase& mesh,
const unsigned int n)
{
libmesh_assert_greater (n, 0);
// Check for an easy return
if (n == 1)
{
this->single_partition (mesh);
return;
}
// Create a simple linear partitioning
{
START_LOG ("partition()", "LinearPartitioner");
const dof_id_type n_active_elem = mesh.n_active_elem();
const dof_id_type blksize = n_active_elem/n;
dof_id_type e = 0;
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
for ( ; elem_it != elem_end; ++elem_it)
{
if ((e/blksize) < n)
{
Elem *elem = *elem_it;
elem->processor_id() =
libmesh_cast_int<processor_id_type>(e/blksize);
}
else
{
Elem *elem = *elem_it;
elem->processor_id() = 0;
elem = elem->parent();
}
e++;
}
STOP_LOG ("partition()", "LinearPartitioner");
}
}
// ------------------------------------------------------------
// SFCPartitioner implementation
void SFCPartitioner::_do_partition (MeshBase & mesh,
const unsigned int n)
{
libmesh_assert_greater (n, 0);
// Check for an easy return
if (n == 1)
{
this->single_partition (mesh);
return;
}
// What to do if the sfcurves library IS NOT present
#ifndef LIBMESH_HAVE_SFCURVES
libmesh_here();
libMesh::err << "ERROR: The library has been built without" << std::endl
<< "Space Filling Curve support. Using a linear" << std::endl
<< "partitioner instead!" << std::endl;
LinearPartitioner lp;
lp.partition (mesh, n);
// What to do if the sfcurves library IS present
#else
LOG_SCOPE("sfc_partition()", "SFCPartitioner");
const dof_id_type n_active_elem = mesh.n_active_elem();
const dof_id_type n_elem = mesh.n_elem();
// the forward_map maps the active element id
// into a contiguous block of indices
std::vector<dof_id_type>
forward_map (n_elem, DofObject::invalid_id);
// the reverse_map maps the contiguous ids back
// to active elements
std::vector<Elem *> reverse_map (n_active_elem, libmesh_nullptr);
int size = static_cast<int>(n_active_elem);
std::vector<double> x (size);
std::vector<double> y (size);
std::vector<double> z (size);
std::vector<int> table (size);
// We need to map the active element ids into a
// contiguous range.
{
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
dof_id_type el_num = 0;
for (; elem_it != elem_end; ++elem_it)
{
libmesh_assert_less ((*elem_it)->id(), forward_map.size());
libmesh_assert_less (el_num, reverse_map.size());
forward_map[(*elem_it)->id()] = el_num;
reverse_map[el_num] = *elem_it;
el_num++;
}
libmesh_assert_equal_to (el_num, n_active_elem);
}
// Get the centroid for each active element
{
// const_active_elem_iterator elem_it (mesh.const_elements_begin());
// const const_active_elem_iterator elem_end(mesh.const_elements_end());
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
for (; elem_it != elem_end; ++elem_it)
{
const Elem * elem = *elem_it;
libmesh_assert_less (elem->id(), forward_map.size());
const Point p = elem->centroid();
x[forward_map[elem->id()]] = p(0);
y[forward_map[elem->id()]] = p(1);
z[forward_map[elem->id()]] = p(2);
}
}
// build the space-filling curve
if (_sfc_type == "Hilbert")
Sfc::hilbert (&x[0], &y[0], &z[0], &size, &table[0]);
else if (_sfc_type == "Morton")
Sfc::morton (&x[0], &y[0], &z[0], &size, &table[0]);
else
{
libmesh_here();
libMesh::err << "ERROR: Unknown type: " << _sfc_type << std::endl
<< " Valid types are" << std::endl
<< " \"Hilbert\"" << std::endl
<< " \"Morton\"" << std::endl
<< " " << std::endl
<< "Proceeding with a Hilbert curve." << std::endl;
Sfc::hilbert (&x[0], &y[0], &z[0], &size, &table[0]);
}
// Assign the partitioning to the active elements
{
// {
// std::ofstream out ("sfc.dat");
// out << "variables=x,y,z" << std::endl;
// out << "zone f=point" << std::endl;
// for (unsigned int i=0; i<n_active_elem; i++)
// out << x[i] << " "
// << y[i] << " "
// << z[i] << std::endl;
// }
const dof_id_type blksize = (n_active_elem+n-1)/n;
for (dof_id_type i=0; i<n_active_elem; i++)
{
libmesh_assert_less (static_cast<unsigned int>(table[i]-1), reverse_map.size());
Elem * elem = reverse_map[table[i]-1];
elem->processor_id() = cast_int<processor_id_type>
(i/blksize);
}
}
#endif
}
// ------------------------------------------------------------
// MetisPartitioner implementation
void MetisPartitioner::_do_partition (MeshBase & mesh,
const unsigned int n_pieces)
{
libmesh_assert_greater (n_pieces, 0);
libmesh_assert (mesh.is_serial());
// Check for an easy return
if (n_pieces == 1)
{
this->single_partition (mesh);
return;
}
// What to do if the Metis library IS NOT present
#ifndef LIBMESH_HAVE_METIS
libmesh_here();
libMesh::err << "ERROR: The library has been built without" << std::endl
<< "Metis support. Using a space-filling curve" << std::endl
<< "partitioner instead!" << std::endl;
SFCPartitioner sfcp;
sfcp.partition (mesh, n_pieces);
// What to do if the Metis library IS present
#else
LOG_SCOPE("partition()", "MetisPartitioner");
const dof_id_type n_active_elem = mesh.n_active_elem();
// build the graph
// std::vector<Metis::idx_t> options(5);
std::vector<Metis::idx_t> vwgt(n_active_elem);
std::vector<Metis::idx_t> part(n_active_elem);
Metis::idx_t
n = static_cast<Metis::idx_t>(n_active_elem), // number of "nodes" (elements)
// in the graph
// wgtflag = 2, // weights on vertices only,
// // none on edges
// numflag = 0, // C-style 0-based numbering
nparts = static_cast<Metis::idx_t>(n_pieces), // number of subdomains to create
edgecut = 0; // the numbers of edges cut by the
// resulting partition
// Set the options
// options[0] = 0; // use default options
// Metis will only consider the active elements.
// We need to map the active element ids into a
// contiguous range. Further, we want the unique range indexing to be
// independent of the element ordering, otherwise a circular dependency
// can result in which the partitioning depends on the ordering which
// depends on the partitioning...
vectormap<dof_id_type, dof_id_type> global_index_map;
global_index_map.reserve (n_active_elem);
{
std::vector<dof_id_type> global_index;
MeshBase::element_iterator it = mesh.active_elements_begin();
const MeshBase::element_iterator end = mesh.active_elements_end();
MeshCommunication().find_global_indices (mesh.comm(),
MeshTools::bounding_box(mesh),
it, end, global_index);
libmesh_assert_equal_to (global_index.size(), n_active_elem);
for (std::size_t cnt=0; it != end; ++it)
{
const Elem * elem = *it;
global_index_map.insert (std::make_pair(elem->id(), global_index[cnt++]));
}
libmesh_assert_equal_to (global_index_map.size(), n_active_elem);
}
// If we have boundary elements in this mesh, we want to account for
// the connectivity between them and interior elements. We can find
// interior elements from boundary elements, but we need to build up
// a lookup map to do the reverse.
typedef LIBMESH_BEST_UNORDERED_MULTIMAP<const Elem *, const Elem *>
map_type;
map_type interior_to_boundary_map;
{
MeshBase::const_element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::const_element_iterator elem_end = mesh.active_elements_end();
for (; elem_it != elem_end; ++elem_it)
{
const Elem * elem = *elem_it;
// If we don't have an interior_parent then there's nothing to look us
// up.
if ((elem->dim() >= LIBMESH_DIM) ||
!elem->interior_parent())
continue;
// get all relevant interior elements
std::set<const Elem *> neighbor_set;
elem->find_interior_neighbors(neighbor_set);
std::set<const Elem *>::iterator n_it = neighbor_set.begin();
for (; n_it != neighbor_set.end(); ++n_it)
{
// FIXME - non-const versions of the Elem set methods
// would be nice
Elem * neighbor = const_cast<Elem *>(*n_it);
#if defined(LIBMESH_HAVE_UNORDERED_MULTIMAP) || \
defined(LIBMESH_HAVE_TR1_UNORDERED_MULTIMAP) || \
defined(LIBMESH_HAVE_HASH_MULTIMAP) || \
defined(LIBMESH_HAVE_EXT_HASH_MULTIMAP)
interior_to_boundary_map.insert
(std::make_pair(neighbor, elem));
#else
interior_to_boundary_map.insert
(interior_to_boundary_map.begin(),
std::make_pair(neighbor, elem));
#endif
}
}
}
// Invoke METIS, but only on processor 0.
// Then broadcast the resulting decomposition
if (mesh.processor_id() == 0)
{
METIS_CSR_Graph<Metis::idx_t> csr_graph;
csr_graph.offsets.resize(n_active_elem+1, 0);
// Local scope for these
{
// build the graph in CSR format. Note that
// the edges in the graph will correspond to
// face neighbors
#ifdef LIBMESH_ENABLE_AMR
std::vector<const Elem *> neighbors_offspring;
#endif
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
#ifndef NDEBUG
std::size_t graph_size=0;
#endif
// (1) first pass - get the row sizes for each element by counting the number
// of face neighbors. Also populate the vwght array if necessary
for (; elem_it != elem_end; ++elem_it)
{
const Elem * elem = *elem_it;
const dof_id_type elem_global_index =
global_index_map[elem->id()];
libmesh_assert_less (elem_global_index, vwgt.size());
// maybe there is a better weight?
// The weight is used to define what a balanced graph is
if(!_weights)
vwgt[elem_global_index] = elem->n_nodes();
else
vwgt[elem_global_index] = static_cast<Metis::idx_t>((*_weights)[elem->id()]);
unsigned int num_neighbors = 0;
// Loop over the element's neighbors. An element
// adjacency corresponds to a face neighbor
for (unsigned int ms=0; ms<elem->n_neighbors(); ms++)
{
const Elem * neighbor = elem->neighbor(ms);
if (neighbor != libmesh_nullptr)
{
// If the neighbor is active treat it
// as a connection
if (neighbor->active())
num_neighbors++;
#ifdef LIBMESH_ENABLE_AMR
// Otherwise we need to find all of the
// neighbor's children that are connected to
// us and add them
else
{
// The side of the neighbor to which
// we are connected
const unsigned int ns =
neighbor->which_neighbor_am_i (elem);
libmesh_assert_less (ns, neighbor->n_neighbors());
// Get all the active children (& grandchildren, etc...)
// of the neighbor.
// FIXME - this is the wrong thing, since we
// should be getting the active family tree on
// our side only. But adding too many graph
// links may cause hanging nodes to tend to be
// on partition interiors, which would reduce
// communication overhead for constraint
// equations, so we'll leave it.
neighbor->active_family_tree (neighbors_offspring);
// Get all the neighbor's children that
// live on that side and are thus connected
// to us
for (unsigned int nc=0; nc<neighbors_offspring.size(); nc++)
{
const Elem * child =
neighbors_offspring[nc];
// This does not assume a level-1 mesh.
// Note that since children have sides numbered
// coincident with the parent then this is a sufficient test.
if (child->neighbor(ns) == elem)
{
libmesh_assert (child->active());
num_neighbors++;
}
}
}
#endif /* ifdef LIBMESH_ENABLE_AMR */
}
}
// Check for any interior neighbors
if ((elem->dim() < LIBMESH_DIM) &&
elem->interior_parent())
{
// get all relevant interior elements
std::set<const Elem *> neighbor_set;
elem->find_interior_neighbors(neighbor_set);
num_neighbors += neighbor_set.size();
}
// Check for any boundary neighbors
typedef map_type::iterator map_it_type;
std::pair<map_it_type, map_it_type>
bounds = interior_to_boundary_map.equal_range(elem);
num_neighbors += std::distance(bounds.first, bounds.second);
csr_graph.prep_n_nonzeros(elem_global_index, num_neighbors);
#ifndef NDEBUG
graph_size += num_neighbors;
#endif
}
csr_graph.prepare_for_use();
// (2) second pass - fill the compressed adjacency array
elem_it = mesh.active_elements_begin();
for (; elem_it != elem_end; ++elem_it)
{
const Elem * elem = *elem_it;
const dof_id_type elem_global_index =
global_index_map[elem->id()];
unsigned int connection=0;
// Loop over the element's neighbors. An element
// adjacency corresponds to a face neighbor
for (unsigned int ms=0; ms<elem->n_neighbors(); ms++)
{
const Elem * neighbor = elem->neighbor(ms);
if (neighbor != libmesh_nullptr)
{
// If the neighbor is active treat it
// as a connection
if (neighbor->active())
csr_graph(elem_global_index, connection++) = global_index_map[neighbor->id()];
#ifdef LIBMESH_ENABLE_AMR
// Otherwise we need to find all of the
// neighbor's children that are connected to
// us and add them
else
{
// The side of the neighbor to which
// we are connected
const unsigned int ns =
neighbor->which_neighbor_am_i (elem);
libmesh_assert_less (ns, neighbor->n_neighbors());
// Get all the active children (& grandchildren, etc...)
// of the neighbor.
neighbor->active_family_tree (neighbors_offspring);
// Get all the neighbor's children that
// live on that side and are thus connected
// to us
for (unsigned int nc=0; nc<neighbors_offspring.size(); nc++)
{
const Elem * child =
neighbors_offspring[nc];
// This does not assume a level-1 mesh.
// Note that since children have sides numbered
// coincident with the parent then this is a sufficient test.
if (child->neighbor(ns) == elem)
{
libmesh_assert (child->active());
csr_graph(elem_global_index, connection++) = global_index_map[child->id()];
}
}
}
#endif /* ifdef LIBMESH_ENABLE_AMR */
}
}
if ((elem->dim() < LIBMESH_DIM) &&
elem->interior_parent())
{
// get all relevant interior elements
std::set<const Elem *> neighbor_set;
elem->find_interior_neighbors(neighbor_set);
std::set<const Elem *>::iterator n_it = neighbor_set.begin();
for (; n_it != neighbor_set.end(); ++n_it)
{
// FIXME - non-const versions of the Elem set methods
// would be nice
Elem * neighbor = const_cast<Elem *>(*n_it);
csr_graph(elem_global_index, connection++) =
global_index_map[neighbor->id()];
}
}
// Check for any boundary neighbors
typedef map_type::iterator map_it_type;
std::pair<map_it_type, map_it_type>
bounds = interior_to_boundary_map.equal_range(elem);
for (map_it_type it = bounds.first; it != bounds.second; ++it)
{
const Elem * neighbor = it->second;
csr_graph(elem_global_index, connection++) =
global_index_map[neighbor->id()];
}
}
// We create a non-empty vals for a disconnected graph, to
// work around a segfault from METIS.
libmesh_assert_equal_to (csr_graph.vals.size(),
std::max(graph_size,std::size_t(1)));
} // done building the graph
Metis::idx_t ncon = 1;
// Select which type of partitioning to create
// Use recursive if the number of partitions is less than or equal to 8
if (n_pieces <= 8)
Metis::METIS_PartGraphRecursive(&n, &ncon, &csr_graph.offsets[0], &csr_graph.vals[0], &vwgt[0], libmesh_nullptr,
libmesh_nullptr, &nparts, libmesh_nullptr, libmesh_nullptr, libmesh_nullptr,
&edgecut, &part[0]);
// Otherwise use kway
else
Metis::METIS_PartGraphKway(&n, &ncon, &csr_graph.offsets[0], &csr_graph.vals[0], &vwgt[0], libmesh_nullptr,
libmesh_nullptr, &nparts, libmesh_nullptr, libmesh_nullptr, libmesh_nullptr,
&edgecut, &part[0]);
} // end processor 0 part
// Broadcase the resutling partition
mesh.comm().broadcast(part);
// Assign the returned processor ids. The part array contains
// the processor id for each active element, but in terms of
// the contiguous indexing we defined above
{
MeshBase::element_iterator it = mesh.active_elements_begin();
const MeshBase::element_iterator end = mesh.active_elements_end();
for (; it!=end; ++it)
{
Elem * elem = *it;
libmesh_assert (global_index_map.count(elem->id()));
const dof_id_type elem_global_index =
global_index_map[elem->id()];
libmesh_assert_less (elem_global_index, part.size());
const processor_id_type elem_procid =
static_cast<processor_id_type>(part[elem_global_index]);
elem->processor_id() = elem_procid;
}
}
#endif
}
// ------------------------------------------------------------
// MetisPartitioner implementation
void MetisPartitioner::_do_partition (MeshBase& mesh,
const unsigned int n_pieces)
{
libmesh_assert_greater (n_pieces, 0);
libmesh_assert (mesh.is_serial());
// Check for an easy return
if (n_pieces == 1)
{
this->single_partition (mesh);
return;
}
// What to do if the Metis library IS NOT present
#ifndef LIBMESH_HAVE_METIS
libmesh_here();
libMesh::err << "ERROR: The library has been built without" << std::endl
<< "Metis support. Using a space-filling curve" << std::endl
<< "partitioner instead!" << std::endl;
SFCPartitioner sfcp;
sfcp.partition (mesh, n_pieces);
// What to do if the Metis library IS present
#else
START_LOG("partition()", "MetisPartitioner");
const dof_id_type n_active_elem = mesh.n_active_elem();
// build the graph
// std::vector<int> options(5);
std::vector<int> vwgt(n_active_elem);
std::vector<int> part(n_active_elem);
int
n = static_cast<int>(n_active_elem), // number of "nodes" (elements)
// in the graph
// wgtflag = 2, // weights on vertices only,
// // none on edges
// numflag = 0, // C-style 0-based numbering
nparts = static_cast<int>(n_pieces), // number of subdomains to create
edgecut = 0; // the numbers of edges cut by the
// resulting partition
// Set the options
// options[0] = 0; // use default options
// Metis will only consider the active elements.
// We need to map the active element ids into a
// contiguous range. Further, we want the unique range indexing to be
// independednt of the element ordering, otherwise a circular dependency
// can result in which the partitioning depends on the ordering which
// depends on the partitioning...
std::map<const Elem*, dof_id_type> global_index_map;
{
std::vector<dof_id_type> global_index;
MeshBase::element_iterator it = mesh.active_elements_begin();
const MeshBase::element_iterator end = mesh.active_elements_end();
MeshCommunication().find_global_indices (MeshTools::bounding_box(mesh),
it, end, global_index);
libmesh_assert_equal_to (global_index.size(), n_active_elem);
for (std::size_t cnt=0; it != end; ++it)
{
const Elem *elem = *it;
libmesh_assert (!global_index_map.count(elem));
global_index_map[elem] = global_index[cnt++];
}
libmesh_assert_equal_to (global_index_map.size(), n_active_elem);
}
// build the graph in CSR format. Note that
// the edges in the graph will correspond to
// face neighbors
std::vector<int> xadj, adjncy;
{
std::vector<const Elem*> neighbors_offspring;
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
// This will be exact when there is no refinement and all the
// elements are of the same type.
std::size_t graph_size=0;
std::vector<std::vector<dof_id_type> > graph(n_active_elem);
for (; elem_it != elem_end; ++elem_it)
{
const Elem* elem = *elem_it;
libmesh_assert (global_index_map.count(elem));
const dof_id_type elem_global_index =
global_index_map[elem];
libmesh_assert_less (elem_global_index, vwgt.size());
libmesh_assert_less (elem_global_index, graph.size());
// maybe there is a better weight?
// The weight is used to define what a balanced graph is
if(!_weights)
vwgt[elem_global_index] = elem->n_nodes();
else
vwgt[elem_global_index] = static_cast<int>((*_weights)[elem->id()]);
// Loop over the element's neighbors. An element
// adjacency corresponds to a face neighbor
for (unsigned int ms=0; ms<elem->n_neighbors(); ms++)
{
const Elem* neighbor = elem->neighbor(ms);
if (neighbor != NULL)
{
// If the neighbor is active treat it
// as a connection
if (neighbor->active())
{
libmesh_assert (global_index_map.count(neighbor));
const dof_id_type neighbor_global_index =
global_index_map[neighbor];
graph[elem_global_index].push_back(neighbor_global_index);
graph_size++;
}
#ifdef LIBMESH_ENABLE_AMR
// Otherwise we need to find all of the
// neighbor's children that are connected to
// us and add them
else
{
// The side of the neighbor to which
// we are connected
const unsigned int ns =
neighbor->which_neighbor_am_i (elem);
libmesh_assert_less (ns, neighbor->n_neighbors());
// Get all the active children (& grandchildren, etc...)
// of the neighbor.
neighbor->active_family_tree (neighbors_offspring);
// Get all the neighbor's children that
// live on that side and are thus connected
// to us
for (unsigned int nc=0; nc<neighbors_offspring.size(); nc++)
{
const Elem* child =
neighbors_offspring[nc];
// This does not assume a level-1 mesh.
// Note that since children have sides numbered
// coincident with the parent then this is a sufficient test.
if (child->neighbor(ns) == elem)
{
libmesh_assert (child->active());
libmesh_assert (global_index_map.count(child));
const dof_id_type child_global_index =
global_index_map[child];
graph[elem_global_index].push_back(child_global_index);
graph_size++;
}
}
}
#endif /* ifdef LIBMESH_ENABLE_AMR */
}
}
}
// Convert the graph into the format Metis wants
xadj.reserve(n_active_elem+1);
adjncy.reserve(graph_size);
for (std::size_t r=0; r<graph.size(); r++)
{
xadj.push_back(adjncy.size());
std::vector<dof_id_type> graph_row; // build this emtpy
graph_row.swap(graph[r]); // this will deallocate at the end of scope
adjncy.insert(adjncy.end(),
graph_row.begin(),
graph_row.end());
}
// The end of the adjacency array for the last elem
xadj.push_back(adjncy.size());
libmesh_assert_equal_to (adjncy.size(), graph_size);
libmesh_assert_equal_to (xadj.size(), n_active_elem+1);
} // done building the graph
if (adjncy.empty())
adjncy.push_back(0);
int ncon = 1;
// Select which type of partitioning to create
// Use recursive if the number of partitions is less than or equal to 8
if (n_pieces <= 8)
Metis::METIS_PartGraphRecursive(&n, &ncon, &xadj[0], &adjncy[0], &vwgt[0], NULL,
NULL, &nparts, NULL, NULL, NULL,
&edgecut, &part[0]);
// Otherwise use kway
else
Metis::METIS_PartGraphKway(&n, &ncon, &xadj[0], &adjncy[0], &vwgt[0], NULL,
NULL, &nparts, NULL, NULL, NULL,
&edgecut, &part[0]);
// Assign the returned processor ids. The part array contains
// the processor id for each active element, but in terms of
// the contiguous indexing we defined above
{
MeshBase::element_iterator it = mesh.active_elements_begin();
const MeshBase::element_iterator end = mesh.active_elements_end();
for (; it!=end; ++it)
{
Elem* elem = *it;
libmesh_assert (global_index_map.count(elem));
const dof_id_type elem_global_index =
global_index_map[elem];
libmesh_assert_less (elem_global_index, part.size());
const processor_id_type elem_procid =
static_cast<processor_id_type>(part[elem_global_index]);
elem->processor_id() = elem_procid;
}
}
STOP_LOG("partition()", "MetisPartitioner");
#endif
}
