Line data    Source code

       1             : // The libMesh Finite Element Library.
       2             : // Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
       3             : 
       4             : // This library is free software; you can redistribute it and/or
       5             : // modify it under the terms of the GNU Lesser General Public
       6             : // License as published by the Free Software Foundation; either
       7             : // version 2.1 of the License, or (at your option) any later version.
       8             : 
       9             : // This library is distributed in the hope that it will be useful,
      10             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12             : // Lesser General Public License for more details.
      13             : 
      14             : // You should have received a copy of the GNU Lesser General Public
      15             : // License along with this library; if not, write to the Free Software
      16             : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      17             : 
      18             : 
      19             : 
      20             : // Local Includes
      21             : #include "libmesh/linear_partitioner.h"
      22             : #include "libmesh/libmesh_logging.h"
      23             : #include "libmesh/elem.h"
      24             : #include "libmesh/enum_partitioner_type.h"
      25             : #include "libmesh/parallel.h"
      26             : 
      27             : namespace libMesh
      28             : {
      29             : 
      30         142 : PartitionerType LinearPartitioner::type() const
      31             : {
      32         142 :   return LINEAR_PARTITIONER;
      33             : }
      34             : 
      35             : 
      36        2194 : void LinearPartitioner::partition_range(MeshBase & mesh,
      37             :                                         MeshBase::element_iterator it,
      38             :                                         MeshBase::element_iterator end,
      39             :                                         const unsigned int n)
      40             : {
      41        2194 :   const bool mesh_is_serial = mesh.is_serial();
      42             : 
      43             :   // Check for easy returns
      44        2194 :   if (it == end && mesh_is_serial)
      45          71 :     return;
      46             : 
      47        2123 :   if (n == 1)
      48             :     {
      49           0 :       this->single_partition_range (it, end);
      50           0 :       return;
      51             :     }
      52             : 
      53          50 :   libmesh_assert_greater (n, 0);
      54             : 
      55             :   // Create a simple linear partitioning
      56         100 :   LOG_SCOPE ("partition_range()", "LinearPartitioner");
      57             : 
      58             :   // This has to be an ordered set
      59         100 :   std::set<dof_id_type> element_ids;
      60             : 
      61             :   // If we're on a serialized mesh, we know our range is the same on
      62             :   // every processor.
      63        2123 :   if (mesh_is_serial)
      64             :     {
      65             :       const dof_id_type blksize = cast_int<dof_id_type>
      66        1034 :         (std::distance(it, end) / n);
      67             : 
      68          44 :       dof_id_type e = 0;
      69       23813 :       for (auto & elem : as_range(it, end))
      70             :         {
      71       21789 :           if ((e/blksize) < n)
      72       20187 :             elem->processor_id() = cast_int<processor_id_type>(e/blksize);
      73             :           else
      74        1602 :             elem->processor_id() = 0;
      75             : 
      76       21789 :           e++;
      77         946 :         }
      78             :     }
      79             :   // If we're on a replicated mesh, we might have different ranges on
      80             :   // different processors, and we'll need to gather the full range.
      81             :   //
      82             :   // This is not an efficient way to do this, but if you want to be
      83             :   // efficient then you want to be using a different partitioner to
      84             :   // begin with; LinearPartitioner is more for debugging than
      85             :   // performance.
      86             :   else
      87             :     {
      88       19447 :       for (const auto & elem : as_range(it, end))
      89       18352 :         element_ids.insert(elem->id());
      90             : 
      91        1089 :       mesh.comm().set_union(element_ids);
      92             : 
      93             :       const dof_id_type blksize = cast_int<dof_id_type>
      94        1089 :         (element_ids.size() / n);
      95             : 
      96           6 :       dof_id_type e = 0;
      97       56193 :       for (auto eid : element_ids)
      98             :         {
      99       55104 :           Elem * elem = mesh.query_elem_ptr(eid);
     100       55104 :           if (elem)
     101             :             {
     102       17275 :               if ((e/blksize) < n)
     103       16432 :                 elem->processor_id() = cast_int<processor_id_type>(e/blksize);
     104             :               else
     105         843 :                 elem->processor_id() = 0;
     106             :             }
     107             : 
     108       55104 :           e++;
     109             :         }
     110             :     }
     111             : }
     112             : 
     113             : 
     114             : 
     115        1798 : void LinearPartitioner::_do_partition (MeshBase & mesh,
     116             :                                        const unsigned int n)
     117             : {
     118        1798 :   this->partition_range(mesh,
     119        3596 :                         mesh.active_elements_begin(),
     120        1850 :                         mesh.active_elements_end(),
     121         104 :                         n);
     122        1798 : }
     123             : 
     124             : } // namespace libMesh