Speed conv_fusion_op for identity activation. (#14744)

* Refine conv_fusion_op for identity activation.
* Fix unit testing.
test=develop

paddle/fluid/operators/conv_fusion_op.cu.cc

@@ -110,11 +110,7 @@ class CUDNNConvFusionOpKernel : public framework::OpKernel<T> {
 
     auto x_dims = framework::vectorize(input->dims());
     auto f_dims = framework::vectorize(filter->dims());
-    if (activation == "identity") {
-      // Only the CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM algo is
-      // enabled with CUDNN_ACTIVATION_IDENTITY in cuDNN lib.
-      algo = CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM;
-    } else if (!exhaustive_search) {
+    if (!exhaustive_search) {
       CUDNN_ENFORCE(platform::dynload::cudnnGetConvolutionForwardAlgorithm(
           handle, cudnn_input_desc, cudnn_filter_desc, cudnn_conv_desc,
           cudnn_output_desc, CUDNN_CONVOLUTION_FWD_SPECIFY_WORKSPACE_LIMIT,
@@ -165,18 +161,42 @@ class CUDNNConvFusionOpKernel : public framework::OpKernel<T> {
     PADDLE_ENFORCE_LE(workspace_size_in_bytes, workspace_size_limit,
                       "workspace_size to be allocated exceeds the limit");
 
-    // ------------------- cudnn conv+bias+act forward --------------------
-    ScalingParamType<T> alpha1 = 1.0f;
-    ScalingParamType<T> alpha2 = residual ? 1.0f : 0.0f;
-    auto cudnn_func = [&](void* cudnn_workspace) {
-      CUDNN_ENFORCE(platform::dynload::cudnnConvolutionBiasActivationForward(
-          handle, &alpha1, cudnn_input_desc, input_data, cudnn_filter_desc,
-          filter_data, cudnn_conv_desc, algo, cudnn_workspace,
-          workspace_size_in_bytes, &alpha2, cudnn_output_desc, residual_data,
-          cudnn_bias_desc, bias_data, cudnn_act_desc, cudnn_output_desc,
+    if ((activation == "identity") &&
+        (algo != CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM) &&
+        (!residual)) {
+      // Only the CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM algo is
+      // enabled with CUDNN_ACTIVATION_IDENTITY in cuDNN lib.
+      // But test in some case, the speed is slower, change to use
+      // cudnnConvolutionForward and cudnnAddTensor
+      // ------------- cudnn conv forward and bias add ---------------------
+      ScalingParamType<T> alpha = 1.0f, beta = 0.0f;
+      auto cudnn_func = [&](void* cudnn_workspace) {
+        CUDNN_ENFORCE(platform::dynload::cudnnConvolutionForward(
+            handle, &alpha, cudnn_input_desc, input_data, cudnn_filter_desc,
+            filter_data, cudnn_conv_desc, algo, cudnn_workspace,
+            workspace_size_in_bytes, &beta, cudnn_output_desc, output_data));
+      };
+      workspace_handle.RunFunc(cudnn_func, workspace_size_in_bytes);
+      CUDNN_ENFORCE(platform::dynload::cudnnAddTensor(
+          handle, &alpha, cudnn_bias_desc, bias_data, &alpha, cudnn_output_desc,
           output_data));
-    };
-    workspace_handle.RunFunc(cudnn_func, workspace_size_in_bytes);
+    } else {
+      if (activation == "identity") {
+        algo = CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM;
+      }
+      // ------------------- cudnn conv+bias+act forward --------------------
+      ScalingParamType<T> alpha1 = 1.0f;
+      ScalingParamType<T> alpha2 = residual ? 1.0f : 0.0f;
+      auto cudnn_func = [&](void* cudnn_workspace) {
+        CUDNN_ENFORCE(platform::dynload::cudnnConvolutionBiasActivationForward(
+            handle, &alpha1, cudnn_input_desc, input_data, cudnn_filter_desc,
+            filter_data, cudnn_conv_desc, algo, cudnn_workspace,
+            workspace_size_in_bytes, &alpha2, cudnn_output_desc, residual_data,
+            cudnn_bias_desc, bias_data, cudnn_act_desc, cudnn_output_desc,
+            output_data));
+      };
+      workspace_handle.RunFunc(cudnn_func, workspace_size_in_bytes);
+    }
   }
 };
 #endif

python/paddle/fluid/tests/unittests/test_conv2d_fusion_op.py

@@ -128,6 +128,12 @@ class TestIdentityActivation(TestConv2dFusionOp):
         self.activation = 'identity'
 
 
+class TestIdentityActivation(TestConv2dFusionOp):
+    def init_activation(self):
+        self.activation = 'identity'
+        self.add_residual_data = False
+
+
 class TestWithGroup(TestConv2dFusionOp):
     def init_group(self):
         self.groups = 3