#2201: annotated code for side-by-side comparison with LBAF

src/vt/vrt/collection/balance/temperedlb/temperedlb.cc

@@ -1895,35 +1895,41 @@ void TemperedLB::swapClusters() {
 
   auto const this_node = theContext()->getNode();
 
+  // Iddentify and perform beneficial cluster swaps
+  int n_rank_swaps = 0;
   for (auto const& [try_rank, try_clusters] : other_rank_clusters_) {
     bool found_potential_good_swap = false;
 
     // if (try_clusters.size() < cur_clusters_.size()) {
     //   proxy_[try_rank].template send<&TemperedLB::tryLock>(this_node, 100);
     //   continue;
     // }
-
+
+    // Iterate over source clusters
     for (auto const& [src_shared_id, src_cluster] : cur_clusters_) {
       auto const& [src_cluster_bytes, src_cluster_load] = src_cluster;
 
+      // Iterate over target clusters
       for (auto const& [try_shared_id, try_cluster] : try_clusters) {
         auto const& [try_cluster_bytes, try_cluster_load] = try_cluster;
+	// Decide whether swap is beneficial
         double c_try = criterion(
           std::make_tuple(src_shared_id, src_cluster_bytes, src_cluster_load),
           std::make_tuple(try_rank, try_shared_id, try_cluster_bytes, try_cluster_load)
         );
         if (c_try > 0.0) {
+	  // Try to perform swap
           found_potential_good_swap = true;
-          // request lock
           proxy_[try_rank].template send<&TemperedLB::tryLock>(this_node, c_try);
+	  n_rank_swaps;
           break;
         }
       }
       if (found_potential_good_swap) {
         break;
-      }
-    }
-  }
+      } // try_clusters
+    } // cur_clusters_
+  } // other_rank_clusters
 
   // We have to be very careful here since we will allow some reentrancy here.
   constexpr int turn_scheduler_times = 10;