refine parallel

paddle/fluid/framework/parallel_executor.cc

@@ -13,6 +13,7 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #include "paddle/fluid/framework/parallel_executor.h"
+#include <string>
 
 #include "ThreadPool.h"
 
@@ -102,15 +103,18 @@ void ParallelExecutor::BCastParamsToGPUs(
   auto *main_scope = member_->local_scopes_[0];
 
   for (auto *var_desc : startup_program.Block(0).AllVars()) {
+    size_t idx = var_desc->Name().find("@GRAD");
+    if (idx != std::string::npos) continue;
     if (var_desc->GetType() == proto::VarType::LOD_TENSOR) {
       auto &main_tensor =
           main_scope->FindVar(var_desc->Name())->Get<LoDTensor>();
-      ncclDataType_t data_type = platform::ToNCCLDataType(main_tensor.type());
+
       auto &dims = main_tensor.dims();
-      size_t numel = main_tensor.numel();
 
+      if (paddle::platform::is_gpu_place(main_tensor.place())) {
+        size_t numel = main_tensor.numel();
+        ncclDataType_t data_type = platform::ToNCCLDataType(main_tensor.type());
         platform::NCCLGroupGuard guard;
-
         for (size_t i = 0; i < member_->places_.size(); ++i) {
           auto place = member_->places_[i];
           void *buffer;
@@ -118,15 +122,25 @@ void ParallelExecutor::BCastParamsToGPUs(
             buffer = const_cast<void *>(main_tensor.data<void>());
           } else {
             auto local_scope = member_->local_scopes_[i];
-          auto *t = local_scope->Var(var_desc->Name())->GetMutable<LoDTensor>();
+            auto *t =
+                local_scope->Var(var_desc->Name())->GetMutable<LoDTensor>();
             t->Resize(dims);
             buffer = t->mutable_data(place, main_tensor.type());
           }
-
           auto &nccl_ctx = member_->nccl_ctxs_->at(place);
           platform::dynload::ncclBcast(buffer, numel, data_type, 0,
                                        nccl_ctx.comm_, nccl_ctx.stream());
         }
+      } else {
+        platform::CPUPlace cpu;
+        for (size_t i = 1; i < member_->places_.size(); ++i) {
+          auto local_scope = member_->local_scopes_[i];
+          auto *t = local_scope->Var(var_desc->Name())->GetMutable<LoDTensor>();
+          t->Resize(dims);
+          t->mutable_data(cpu, main_tensor.type());
+          paddle::framework::TensorCopy(main_tensor, cpu, t);
+        }
+      }
     }
     member_->nccl_ctxs_->WaitAll();
   }