Add reference to global_gather and global_scatter operators (#36985)

* add reference to global_gather and global_scatter operators

paddle/fluid/operators/collective/global_gather_op.cu.cc

@@ -10,7 +10,7 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License. */
+limitations under the License.*/
 
 #include "paddle/fluid/operators/collective/global_gather_op.h"
 
@@ -101,7 +101,8 @@ class GlobalGatherOpCUDAKernel : public framework::OpKernel<T> {
     auto send_ptr = 0;
     auto send_buf = x->data<T>();
     auto recv_buf = out->mutable_data<T>(out_dims, place);
-
+    // Taken and modified for PaddlePaddle from:
+    // https://github.com/laekov/fastmoe
     for (auto i = 0; i < n_expert; ++i) {
       PADDLE_ENFORCE_CUDA_SUCCESS(platform::dynload::ncclGroupStart());
       for (auto j = 0; j < nranks; ++j) {

paddle/fluid/operators/collective/global_scatter_op.cu.cc

@@ -10,7 +10,7 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License. */
+limitations under the License.*/
 
 #include "paddle/fluid/operators/collective/global_scatter_op.h"
 
@@ -100,7 +100,8 @@ class GlobalScatterOpCUDAKernel : public framework::OpKernel<T> {
     auto recv_ptr = 0;
     auto send_buf = x->data<T>();
     auto recv_buf = out->mutable_data<T>(out_dims, place);
-
+    // Taken and modified for PaddlePaddle from:
+    // https://github.com/laekov/fastmoe
     for (auto i = 0; i < n_expert; ++i) {
       PADDLE_ENFORCE_CUDA_SUCCESS(platform::dynload::ncclGroupStart());
       for (auto j = 0; j < nranks; ++j) {