Changes for more resonable partitioning:

- option to not remove anything from partitioning graph
- added possibility for setting overlap
- changed export list: need testing in particular in parallel (if it is intended to work there)

opm/grid/CpGrid.hpp

@@ -1219,10 +1219,10 @@ namespace Dune
         /// \param overlapLayers The number of layers of cells of the overlap region (default: 1).
         /// \param partitionMethod The method used to partition the grid, one of Dune::PartitionMethod
         /// \warning May only be called once.
-        bool loadBalance(int overlapLayers=1, int partitionMethod = Dune::PartitionMethod::zoltan, double imbalanceTol = 1.1)
+        bool loadBalance(int overlapLayers=1, int partitionMethod = Dune::PartitionMethod::zoltan, double imbalanceTol = 1.1, bool addCorners = true)
         {
             using std::get;
-            return get<0>(scatterGrid(defaultTransEdgeWgt, false, nullptr, {}, false, nullptr, true, overlapLayers, partitionMethod, imbalanceTol));
+            return get<0>(scatterGrid(defaultTransEdgeWgt, false, nullptr, {}, false, nullptr, addCorners, overlapLayers, partitionMethod, imbalanceTol));
         }
 
         // loadbalance is not part of the grid interface therefore we skip it.

opm/grid/common/GridPartitioning.cpp

@@ -391,7 +391,8 @@ void addOverlapLayer(const CpGrid& grid, int index, const CpGrid::Codim<0>::Enti
                 {
                     // Note: multiple adds for same process are possible
                     exportList.emplace_back(nb_index, owner, AttributeSet::copy);
-                    exportList.emplace_back(index, cell_part[nb_index],  AttributeSet::copy);
+                    // not need or check if
+                    //exportList.emplace_back(index, cell_part[nb_index],  AttributeSet::copy);
                     if ( recursion_deps>0 )
                     {
                         // Add another layer

opm/grid/common/ZoltanPartition.cpp

@@ -286,7 +286,7 @@ void setDefaultZoltanParameters(Zoltan_Struct* zz) {
     Zoltan_Set_Param(zz, "CHECK_GRAPH", "2");
     Zoltan_Set_Param(zz,"EDGE_WEIGHT_DIM","0");
     Zoltan_Set_Param(zz, "OBJ_WEIGHT_DIM", "0");
-    Zoltan_Set_Param(zz, "PHG_EDGE_SIZE_THRESHOLD", ".35");  /* 0-remove all, 1-remove none */
+    Zoltan_Set_Param(zz, "PHG_EDGE_SIZE_THRESHOLD", "1");  /* 0-remove all, 1-remove none */
 }
 
 

opm/grid/cpgrid/CpGrid.cpp

@@ -225,7 +225,7 @@ CpGrid::scatterGrid(EdgeWeightMethod method,
     // Silence any unused argument warnings that could occur with various configurations.
     static_cast<void>(wells);
     static_cast<void>(transmissibilities);
-    static_cast<void>(overlapLayers);
+    //static_cast<void>(overlapLayers);
     static_cast<void>(method);
     static_cast<void>(imbalanceTol);
 
@@ -373,7 +373,7 @@ CpGrid::scatterGrid(EdgeWeightMethod method,
 
         // first create the overlap
         auto noImportedOwner = addOverlapLayer(*this, computedCellPart, exportList, importList, cc, addCornerCells,
-                                               transmissibilities);
+                                               transmissibilities, overlapLayers);
         // importList contains all the indices that will be here.
         auto compareImport = [](const std::tuple<int,int,char,int>& t1,
                                 const std::tuple<int,int,char,int>&t2)