Make use of METIS an option when ParMETIS is configured

Make reports a little less specific

examples/main.c

@@ -492,12 +492,20 @@ int main(int argc, char *argv[]) {
 
   /* Let's report what we did */
   if (myrank == 0) {
-    message("Using initial partition %s",
+#if defined(HAVE_PARMETIS)
+    if (reparttype.usemetis)
+       message("Using METIS serial partitioning:");
+    else
+       message("Using ParMETIS partitioning:");
+#else
+    message("Using METIS serial partitioning:");
+#endif
+    message("  initial partitioning: %s",
             initial_partition_name[initial_partition.type]);
     if (initial_partition.type == INITPART_GRID)
-      message("grid set to [ %i %i %i ].", initial_partition.grid[0],
+      message("    grid set to [ %i %i %i ].", initial_partition.grid[0],
               initial_partition.grid[1], initial_partition.grid[2]);
-    message("Using %s repartitioning", repartition_name[reparttype.type]);
+    message("  repartitioning: %s", repartition_name[reparttype.type]);
   }
 #endif
 

examples/parameter_example.yml

@@ -125,7 +125,9 @@ DomainDecomposition:
                             # new decomposition, or number of steps (>1) between decompositions
   minfrac:          0.9     # (Optional) Fractional of all particles that should be updated in previous step when
                             # using CPU time trigger
-  itr               0.1     # Ratio of inter node communication time to data redistribution time, in the range 0.00001 to 10000000.0. 
+  usemetis          0       # Use serial METIS when ParMETIS is also available.
+  adaptive          1       # Use adaptive repartition when ParMETIS is available, otherwise simple refinement.
+  itr               100     # When adaptive defines the ratio of inter node communication time to data redistribution time, in the range 0.00001 to 10000000.0.
                             # Lower values give less data movement during redistributions, at the cost of global balance which may require more communication.
 
 # Parameters related to the equation of state ------------------------------------------

src/partition.c

@@ -60,17 +60,18 @@
 
 /* Simple descriptions of initial partition types for reports. */
 const char *initial_partition_name[] = {
-    "axis aligned grids of cells", "vectorized point associated cells",
-    "memory balanced, using METIS particle weighted cells",
-    "similar sized regions, using METIS unweighted cells"};
+    "axis aligned grids of cells",
+    "vectorized point associated cells",
+    "memory balanced, using particle weighted cells",
+    "similar sized regions, using unweighted cells"};
 
 /* Simple descriptions of repartition types for reports. */
 const char *repartition_name[] = {
-    "no",
-    "METIS edge and vertex task cost weights",
-    "METIS task cost edge weights",
-    "METIS task cost vertex weights",
-    "METIS vertex task costs and edge delta timebin weights"
+    "none",
+    "edge and vertex task cost weights",
+    "task cost edge weights",
+    "task cost vertex weights",
+    "vertex task costs and edge delta timebin weights"
 };
 
 /* Local functions, if needed. */
@@ -871,7 +872,7 @@ static void pick_parmetis(int nodeID, struct space *s, int nregions,
 }
 #endif
 
-#if defined(WITH_MPI) && defined(HAVE_METIS) && !defined(HAVE_PARMETIS)
+#if defined(WITH_MPI) && defined(HAVE_METIS)
 /**
  * @brief Partition the given space into a number of connected regions.
  *
@@ -1246,9 +1247,13 @@ static void repart_edge_metis(int vweights, int eweights, int timebins,
 
   /* And repartition/ partition, using both weights or not as requested. */
 #ifdef HAVE_PARMETIS
-  pick_parmetis(nodeID, s, nr_nodes, weights_v, weights_e, refine,
-                repartition->adaptive, repartition->itr,
-                repartition->celllist);
+  if (repartition->usemetis) {
+    pick_metis(nodeID, s, nr_nodes, weights_v, weights_e, repartition->celllist);
+  } else {
+    pick_parmetis(nodeID, s, nr_nodes, weights_v, weights_e, refine,
+                  repartition->adaptive, repartition->itr,
+                  repartition->celllist);
+  }
 #else
   pick_metis(nodeID, s, nr_nodes, weights_v, weights_e, repartition->celllist);
 #endif
@@ -1423,7 +1428,11 @@ void partition_initial_partition(struct partition *initial_partition,
     if ((celllist = (int *)malloc(sizeof(int) * s->nr_cells)) == NULL)
       error("Failed to allocate celllist");
 #ifdef HAVE_PARMETIS
+  if (initial_partition->usemetis) {
+    pick_metis(nodeID, s, nr_nodes, weights, NULL, celllist);
+  } else {
     pick_parmetis(nodeID, s, nr_nodes, weights, NULL, 0, 0, 0.0f, celllist);
+  }
 #else
     pick_metis(nodeID, s, nr_nodes, weights, NULL, celllist);
 #endif
@@ -1595,13 +1604,18 @@ void partition_init(struct partition *partition,
         "Invalid DomainDecomposition:minfrac, must be greater than 0 and less "
         "than equal to 1");
 
+  /* Use METIS or ParMETIS when ParMETIS is also available. */
+  repartition->usemetis =
+      parser_get_opt_param_int(params, "DomainDecomposition:usemetis", 0);
+  partition->usemetis = repartition->usemetis;
+
   /* Use adaptive or simple refinement when repartitioning. */
-  repartition->adaptive = 
-      parser_get_opt_param_int(params, "DomainDecomposition:adaptive", 1   );
+  repartition->adaptive =
+      parser_get_opt_param_int(params, "DomainDecomposition:adaptive", 1);
 
   /* Ratio of interprocess communication time to data redistribution time. */
   repartition->itr =
-      parser_get_opt_param_float(params, "DomainDecomposition:itr", 0.1f);
+      parser_get_opt_param_float(params, "DomainDecomposition:itr", 100.0f);
 
   /* Clear the celllist for use. */
   repartition->ncelllist = 0;

src/partition.h

@@ -38,6 +38,7 @@ extern const char *initial_partition_name[];
 struct partition {
   enum partition_type type;
   int grid[3];
+  int usemetis;
 };
 
 /* Repartition type to use. */
@@ -55,6 +56,7 @@ struct repartition {
   float trigger;
   float minfrac;
   float itr;
+  int usemetis;
   int adaptive;
 
   /* The partition as a cell-list. */