From 5bd1e73f5e6e7532bd1b13b1c0924ba70ae5cd1a Mon Sep 17 00:00:00 2001
From: dangqingqing <dangqingqing@baidu.com>
Date: Tue, 5 Dec 2017 00:25:39 +0800
Subject: [PATCH] Refine and speedup momentum operator.

---
 paddle/operators/momentum_op.cc |  4 +-
 paddle/operators/momentum_op.cu | 66 +++++++++++++++++++++++++++++++--
 paddle/operators/momentum_op.h  | 13 +++----
 3 files changed, 70 insertions(+), 13 deletions(-)

diff --git a/paddle/operators/momentum_op.cc b/paddle/operators/momentum_op.cc
index 19954006195..fde253b0b38 100644
--- a/paddle/operators/momentum_op.cc
+++ b/paddle/operators/momentum_op.cc
@@ -101,5 +101,5 @@ $$
 
 namespace ops = paddle::operators;
 REGISTER_OP_WITHOUT_GRADIENT(momentum, ops::MomentumOp, ops::MomentumOpMaker);
-REGISTER_OP_CPU_KERNEL(
-    momentum, ops::MomentumOpKernel<paddle::platform::CPUPlace, float>);
+REGISTER_OP_CPU_KERNEL(momentum, ops::MomentumOpKernel<float>,
+                       ops::MomentumOpKernel<double>);
diff --git a/paddle/operators/momentum_op.cu b/paddle/operators/momentum_op.cu
index efc24e795e0..d856df40027 100644
--- a/paddle/operators/momentum_op.cu
+++ b/paddle/operators/momentum_op.cu
@@ -12,9 +12,67 @@
    See the License for the specific language governing permissions and
    limitations under the License. */
 
-#define EIGEN_USE_GPU
-#include "paddle/operators/momentum_op.h"
+#include "paddle/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+template <typename T>
+__global__ void MomentumKernel(const T* p, const T* g, const T* v,
+                               const T* learning_rate, const T mu,
+                               const int64_t num, bool use_nesterov, T* p_out,
+                               T* v_out) {
+  T lr = learning_rate[0];
+  if (use_nesterov) {
+    for (int i = blockIdx.x * blockDim.x + threadIdx.x; i < num;
+         i += blockDim.x * gridDim.x) {
+      T g_val = g[i];
+      T v_new = v[i] * mu + g_val;
+      v_out[i] = v_new;
+      p_out[i] = p[i] - g_val * lr + v_new * mu * lr;
+    }
+  } else {
+    for (int i = blockIdx.x * blockDim.x + threadIdx.x; i < num;
+         i += blockDim.x * gridDim.x) {
+      T v_new = v[i] * mu + g[i];
+      v_out[i] = v_new;
+      p_out[i] = p[i] - lr * v_new;
+    }
+  }
+}
+
+template <typename T>
+class MomentumOpCUDAKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto param_out = ctx.Output<framework::Tensor>("ParamOut");
+    auto velocity_out = ctx.Output<framework::Tensor>("VelocityOut");
+    auto param = ctx.Input<framework::Tensor>("Param");
+    auto velocity = ctx.Input<framework::Tensor>("Velocity");
+    auto grad = ctx.Input<framework::Tensor>("Grad");
+    auto learning_rate = ctx.Input<framework::Tensor>("LearningRate");
+
+    T* p_out = param_out->mutable_data<T>(ctx.GetPlace());
+    T* v_out = velocity_out->mutable_data<T>(ctx.GetPlace());
+
+    T mu = static_cast<T>(ctx.Attr<float>("mu"));
+    bool use_nesterov = ctx.Attr<bool>("use_nesterov");
+
+    auto* p = param->data<T>();
+    auto* v = velocity->data<T>();
+    auto* g = grad->data<T>();
+    auto* lr = learning_rate->data<T>();
+
+    int block = 512;
+    int grid = (param->numel() + block - 1) / block;
+    MomentumKernel<T><<<grid, block, 0, ctx.cuda_device_context().stream()>>>(
+        p, g, v, lr, mu, param->numel(), use_nesterov, p_out, v_out);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
 
 namespace ops = paddle::operators;
-REGISTER_OP_GPU_KERNEL(
-    momentum, ops::MomentumOpKernel<paddle::platform::GPUPlace, float>);
+REGISTER_OP_GPU_KERNEL(momentum, ops::MomentumOpCUDAKernel<float>,
+                       ops::MomentumOpCUDAKernel<double>);
diff --git a/paddle/operators/momentum_op.h b/paddle/operators/momentum_op.h
index 8f7f5eb5c21..2d919573d20 100644
--- a/paddle/operators/momentum_op.h
+++ b/paddle/operators/momentum_op.h
@@ -19,7 +19,7 @@ limitations under the License. */
 namespace paddle {
 namespace operators {
 
-template <typename Place, typename T>
+template <typename T>
 class MomentumOpKernel : public framework::OpKernel<T> {
  public:
   void Compute(const framework::ExecutionContext& ctx) const override {
@@ -33,7 +33,7 @@ class MomentumOpKernel : public framework::OpKernel<T> {
     param_out->mutable_data<T>(ctx.GetPlace());
     velocity_out->mutable_data<T>(ctx.GetPlace());
 
-    float mu = ctx.Attr<float>("mu");
+    T mu = static_cast<T>(ctx.Attr<float>("mu"));
     bool use_nesterov = ctx.Attr<bool>("use_nesterov");
 
     auto p_out = framework::EigenVector<T>::Flatten(*param_out);
@@ -42,18 +42,17 @@ class MomentumOpKernel : public framework::OpKernel<T> {
     auto p = framework::EigenVector<T>::Flatten(*param);
     auto v = framework::EigenVector<T>::Flatten(*velocity);
     auto g = framework::EigenVector<T>::Flatten(*grad);
-    auto lr = framework::EigenVector<T>::Flatten(*learning_rate);
+    auto* lr = learning_rate->data<T>();
 
-    auto place = ctx.GetEigenDevice<Place>();
+    auto place = ctx.GetEigenDevice<platform::CPUPlace>();
 
     Eigen::DSizes<int, 1> grad_dsize(grad->numel());
 
     v_out.device(place) = v * mu + g;
     if (use_nesterov) {
-      p_out.device(place) = p - g * lr.broadcast(grad_dsize) +
-                            v_out * mu * lr.broadcast(grad_dsize);
+      p_out.device(place) = p - (g - v_out * mu) * lr[0];
     } else {
-      p_out.device(place) = p - lr.broadcast(grad_dsize) * v_out;
+      p_out.device(place) = p - lr[0] * v_out;
     }
   }
 };
-- 
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