adjust mem_frugal_threshold computation

Author: seunghwak

cpp/src/structure/create_graph_from_edgelist_impl.cuh

@@ -535,10 +535,11 @@ create_graph_from_partitioned_edgelist(
 
   auto total_global_mem = handle.get_device_properties().totalGlobalMem;
   auto constexpr mem_frugal_ratio =
-    0.05;  // if the expected temporary buffer size exceeds the mem_frugal_ratio of the
-           // total_global_mem, switch to the memory frugal approach
+    0.5;  // if the aggregate edge data size exceeds the mem_frugal_ratio of the total_global_mem
+          // (in an approximate sense), switch to the memory frugal approach
   auto mem_frugal_threshold =
-    static_cast<size_t>(static_cast<double>(total_global_mem / element_size) * mem_frugal_ratio);
+    static_cast<size_t>(static_cast<double>(total_global_mem / element_size) * mem_frugal_ratio) /
+    static_cast<size_t>(minor_comm_size);
 
   std::vector<rmm::device_uvector<edge_t>> edge_partition_offsets;
   std::vector<rmm::device_uvector<vertex_t>> edge_partition_indices;