From 323499be9dd754d5416cba9852a58015913de1bc Mon Sep 17 00:00:00 2001
From: Naim <naim@uib.no>
Date: Thu, 14 Mar 2024 17:16:39 +0100
Subject: [PATCH] Address comments from Don

---
 .../graph_operations/graph_operations.cu         | 10 +++++++---
 .../vertex_and_edge_partition.cu                 | 16 ++++++++++------
 .../mg_graph_algorithms.cpp                      | 12 ++++++++----
 .../sg_graph_algorithms.cpp                      |  4 ++--
 4 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/cpp/examples/developers/graph_operations/graph_operations.cu b/cpp/examples/developers/graph_operations/graph_operations.cu
index 6dd460e3ba9..014cedcab7e 100644
--- a/cpp/examples/developers/graph_operations/graph_operations.cu
+++ b/cpp/examples/developers/graph_operations/graph_operations.cu
@@ -72,7 +72,7 @@ std::unique_ptr<raft::handle_t> initialize_mg_handle()
 }
 
 /**
- * @brief Create a graph from edge sources, destinitions, and optional weights
+ * @brief Create a graph from edge sources, destinations, and optional weights
  */
 template <typename vertex_t,
           typename edge_t,
@@ -100,7 +100,9 @@ create_graph(raft::handle_t const& handle,
   auto const comm_size = handle.get_comms().get_size();
 
   //
-  // Assign part of the edge list to each GPU
+  // Assign part of the edge list to each GPU. If there are N edges and P GPUs, each GPU except the
+  // one with rank P-1 reads N/P edges and the GPU with rank P -1 reads (N/P + N%P) edges into GPU
+  // memory.
   //
 
   auto start = comm_rank * (num_edges / comm_size);
@@ -123,7 +125,9 @@ create_graph(raft::handle_t const& handle,
   }
 
   //
-  // Shuffle edges to proper GPU
+  // In cugraph, each vertex and edge is assigned to a specific GPU using hash functions. Before
+  // creating a graph from edges, we need to ensure that all edges are already assigned to the
+  // proper GPU.
   //
 
   if (multi_gpu) {
diff --git a/cpp/examples/developers/vertex_and_edge_partition/vertex_and_edge_partition.cu b/cpp/examples/developers/vertex_and_edge_partition/vertex_and_edge_partition.cu
index 51025c1c2dd..ce02e3b2639 100644
--- a/cpp/examples/developers/vertex_and_edge_partition/vertex_and_edge_partition.cu
+++ b/cpp/examples/developers/vertex_and_edge_partition/vertex_and_edge_partition.cu
@@ -68,7 +68,7 @@ std::unique_ptr<raft::handle_t> initialize_mg_handle()
 }
 
 /**
- * @brief Create a graph from edge sources, destinitions, and optional weights
+ * @brief Create a graph from edge sources, destinations, and optional weights
  */
 template <typename vertex_t,
           typename edge_t,
@@ -96,7 +96,9 @@ create_graph(raft::handle_t const& handle,
   auto const comm_size = handle.get_comms().get_size();
 
   //
-  // Assign part of the edge list to each GPU
+  // Assign part of the edge list to each GPU. If there are N edges and P GPUs, each GPU except the
+  // one with rank P-1 reads N/P edges and the GPU with rank P -1 reads (N/P + N%P) edges into GPU
+  // memory.
   //
 
   auto start = comm_rank * (num_edges / comm_size);
@@ -119,7 +121,9 @@ create_graph(raft::handle_t const& handle,
   }
 
   //
-  // Shuffle edges to proper GPU
+  // In cugraph, each vertex and edge is assigned to a specific GPU using hash functions. Before
+  // creating a graph from edges, we need to ensure that all edges are already assigned to the
+  // proper GPU.
   //
 
   if (multi_gpu) {
@@ -273,10 +277,10 @@ void look_into_vertex_and_edge_partitions(
     auto dcs_nzd_vertices        = edge_partition_view.dcs_nzd_vertices();
 
     //
-    // Print sources and destinitions of edges stored in current edge partition
+    // Print sources and destinations of edges stored in current edge partition
     //
 
-    // print sources and destinitions stored in CSR/CSC format
+    // print sources and destinations stored in CSR/CSC format
     raft::device_span<weight_t const> weights_of_edges_stored_in_this_edge_partition{};
 
     if (is_weighted) {
@@ -330,7 +334,7 @@ void look_into_vertex_and_edge_partitions(
           });
       });
 
-    // print sources and destinitions stored in DCSR/DCSC format
+    // print sources and destinations stored in DCSR/DCSC format
     if (major_hypersparse_first.has_value()) {
       thrust::for_each(
         handle.get_thrust_policy(),
diff --git a/cpp/examples/users/multi_gpu_application/mg_graph_algorithms.cpp b/cpp/examples/users/multi_gpu_application/mg_graph_algorithms.cpp
index c58574cc6c6..a9e2a170208 100644
--- a/cpp/examples/users/multi_gpu_application/mg_graph_algorithms.cpp
+++ b/cpp/examples/users/multi_gpu_application/mg_graph_algorithms.cpp
@@ -64,7 +64,7 @@ std::unique_ptr<raft::handle_t> initialize_mg_handle()
 }
 
 /**
- * @brief Create a graph from edge sources, destinitions, and optional weights
+ * @brief Create a graph from edge sources, destination, and optional weights.
  */
 template <typename vertex_t,
           typename edge_t,
@@ -92,7 +92,9 @@ create_graph(raft::handle_t const& handle,
   auto const comm_size = handle.get_comms().get_size();
 
   //
-  // Assign part of the edge list to each GPU
+  // Assign part of the edge list to each GPU. If there are N edges and P GPUs, each GPU except the
+  // one with rank P-1 reads N/P edges and the GPU with rank P -1 reads (N/P + N%P) edges into GPU
+  // memory.
   //
 
   auto start = comm_rank * (num_edges / comm_size);
@@ -115,7 +117,9 @@ create_graph(raft::handle_t const& handle,
   }
 
   //
-  // Shuffle edges to proper GPU
+  // In cugraph, each vertex and edge is assigned to a specific GPU using hash functions. Before
+  // creating a graph from edges, we need to ensure that all edges are already assigned to the
+  // proper GPU.
   //
 
   if (multi_gpu) {
@@ -250,7 +254,7 @@ int main(int argc, char** argv)
   std::unique_ptr<raft::handle_t> handle = initialize_mg_handle();
 
   //
-  // Create graph from edge source, destinition and weight list
+  // Create graph from edge source, destination and weight list
   //
 
   using vertex_t    = int32_t;
diff --git a/cpp/examples/users/single_gpu_application/sg_graph_algorithms.cpp b/cpp/examples/users/single_gpu_application/sg_graph_algorithms.cpp
index 1c0bdef7257..0233d4f0e84 100644
--- a/cpp/examples/users/single_gpu_application/sg_graph_algorithms.cpp
+++ b/cpp/examples/users/single_gpu_application/sg_graph_algorithms.cpp
@@ -36,7 +36,7 @@ std::unique_ptr<raft::handle_t> initialize_sg_handle()
 }
 
 /**
- * @brief Create a graph from edge sources, destinitions, and optional weights
+ * @brief Create a graph from edge sources, destinations, and optional weights
  */
 template <typename vertex_t,
           typename edge_t,
@@ -192,7 +192,7 @@ int main(int argc, char** argv)
   std::unique_ptr<raft::handle_t> handle = initialize_sg_handle();
 
   //
-  // Create graph from edge source, destinition and weight list
+  // Create graph from edge source, destination and weight list
   //
 
   using vertex_t    = int32_t;