From 9ee1b7bc045091522c53cc69d174bebda979667e Mon Sep 17 00:00:00 2001
From: Yancey1989 <yancey1989@gmail.com>
Date: Thu, 13 Sep 2018 21:17:30 +0800
Subject: [PATCH] add some comments

---
 paddle/fluid/framework/details/multi_devices_graph_pass.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/paddle/fluid/framework/details/multi_devices_graph_pass.cc b/paddle/fluid/framework/details/multi_devices_graph_pass.cc
index 5781936cb3..7e7f1234c2 100644
--- a/paddle/fluid/framework/details/multi_devices_graph_pass.cc
+++ b/paddle/fluid/framework/details/multi_devices_graph_pass.cc
@@ -431,7 +431,9 @@ std::unique_ptr<ir::Graph> MultiDevSSAGraphBuilder::ApplyImpl(
                     CreateReduceOp(&result, g_name, cur_device_id);
                     graph->Get<ShardedVarDevice>(kShardedVarDevice)
                         .emplace(g_name, cur_device_id);
-                    bcast_var_name_set[cur_device_id].emplace(p_name);
+                    if (!is_dist_train) {
+                      bcast_var_name_set[cur_device_id].emplace(p_name);
+                    }
                     break;
                   case BuildStrategy::ReduceStrategy::kAllReduce:
                     if (IsSparseGradient(g_name)) {
@@ -461,7 +463,7 @@ std::unique_ptr<ir::Graph> MultiDevSSAGraphBuilder::ApplyImpl(
   if ((use_gpu &&
        strategy_.reduce_ == BuildStrategy::ReduceStrategy::kReduce) ||
       is_dist_train) {
-    // Insert BCast Ops
+    // allways broadcast receieved parameters for distributed training
     for (size_t dev_id = 0; dev_id < bcast_var_name_set.size(); ++dev_id) {
       auto &to_bcast_set = bcast_var_name_set[dev_id];
       for (auto &bcast_name : to_bcast_set) {
-- 
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