Merge pull request #14051 from velconia/accelerate_embedding_grad

[1.1] Accelerate sparse embedding grad op in CPU device

Author: velconia

paddle/fluid/operators/lookup_table_op.cc

@@ -81,6 +81,12 @@ class LookupTableOpMaker : public framework::OpProtoAndCheckerMaker {
                      "Otherwise the given value indicates padding the output "
                      "with zeros whenever lookup encounters it in Ids.")
         .SetDefault(kNoPadding);
+    // NOTE(minqiyang): grad_inplace is an temporal attribute,
+    // please do NOT set this attribute in python layer.
+    AddAttr<bool>("grad_inplace",
+                  "(boolean, default false) "
+                  "If the grad op reuse the input's variable.")
+        .SetDefault(false);
     AddComment(R"DOC(
 Lookup Table Operator.
 

paddle/fluid/operators/lookup_table_op.h

@@ -21,6 +21,7 @@ limitations under the License. */
 #include "paddle/fluid/framework/lod_tensor.h"
 #include "paddle/fluid/framework/op_registry.h"
 #include "paddle/fluid/framework/selected_rows.h"
+#include "paddle/fluid/operators/math/blas.h"
 
 namespace paddle {
 namespace operators {
@@ -68,15 +69,16 @@ class LookupTableKernel : public framework::OpKernel<T> {
       const auto *table = table_t.value().data<T>();
       auto *output = output_t->mutable_data<T>(context.GetPlace());
 
+      auto blas = math::GetBlas<platform::CPUDeviceContext, T>(context);
       for (int64_t i = 0; i < ids_numel; ++i) {
         if (padding_idx != kNoPadding && ids[i] == padding_idx) {
           memset(output + i * row_width, 0, row_width * sizeof(T));
         } else {
           PADDLE_ENFORCE_GE(ids[i], 0);
           auto id_index = table_t.Index(ids[i]);
           PADDLE_ENFORCE_GE(id_index, 0, "the input key should be exists.");
-          memcpy(output + i * row_width, table + id_index * row_width,
-                 row_width * sizeof(T));
+          blas.VCOPY(row_width, table + id_index * row_width,
+                     output + i * row_width);
         }
       }
     }
@@ -111,27 +113,37 @@ class LookupTableGradKernel : public framework::OpKernel<T> {
       auto *ids_data = ids->data<int64_t>();
       int64_t ids_num = ids->numel();
 
-      framework::Vector<int64_t> new_rows;
-      new_rows.reserve(ids_num);
-      for (int64_t i = 0; i < ids_num; i++) {
-        new_rows.push_back(ids_data[i]);
-      }
+      std::vector<int64_t> new_rows;
+      new_rows.resize(ids_num);
+      std::memcpy(&new_rows[0], ids_data, ids_num * sizeof(int64_t));
       d_table->set_rows(new_rows);
 
       auto *d_table_value = d_table->mutable_value();
       d_table_value->Resize({ids_num, table_dim[1]});
-      d_table_value->mutable_data<T>(context.GetPlace());
-
-      d_table->set_height(table_dim[0]);
-
-      auto *d_output_data = d_output->data<T>();
-      auto *d_table_data = d_table_value->data<T>();
-
-      auto d_output_dims = d_output->dims();
-      PADDLE_ENFORCE_EQ(
-          d_table_value->dims(),
-          framework::flatten_to_2d(d_output_dims, d_output_dims.size() - 1));
-      memcpy(d_table_data, d_output_data, sizeof(T) * d_output->numel());
+      // FIXME(minqiyang):
+      // memory optimization will NOT reuse Tensor with SelectedRows
+      // so we could just share the tensor here directly.
+      // However, the InferVarType method will infer the output SelectedRows
+      // to Tensor sometimes, which is a bug, so we will add an attribute
+      // here to indicate the inplace and remove this attribute after
+      // the InferVarType's bug was fixed
+      bool grad_inplace = context.Attr<bool>("grad_inplace");
+      if (grad_inplace) {
+        d_table_value->ShareDataWith(*d_output);
+      } else {
+        d_table_value->mutable_data<T>(context.GetPlace());
+
+        d_table->set_height(table_dim[0]);
+
+        auto *d_output_data = d_output->data<T>();
+        auto *d_table_data = d_table_value->data<T>();
+
+        auto d_output_dims = d_output->dims();
+        PADDLE_ENFORCE_EQ(
+            d_table_value->dims(),
+            framework::flatten_to_2d(d_output_dims, d_output_dims.size() - 1));
+        memcpy(d_table_data, d_output_data, sizeof(T) * d_output->numel());
+      }
     } else {
       auto *ids = context.Input<LoDTensor>("Ids");
       auto *d_output = context.Input<LoDTensor>(framework::GradVarName("Out"));

python/paddle/fluid/tests/unittests/dist_transformer.py

@@ -1159,6 +1159,7 @@ def prepare_encoder(src_word,
             name=pos_enc_param_name,
             trainable=False,
             initializer=fluid.initializer.ConstantInitializer(0.001)))
+    src_pos_enc.stop_gradient = True
     enc_input = src_word_emb + src_pos_enc
     return layers.dropout(
         enc_input,