Merge pull request #3817 from xinghai-sun/dropout

Add dropout operator.

paddle/operators/dropout_op.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   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. */
+
+#include "paddle/operators/dropout_op.h"
+
+namespace paddle {
+namespace operators {
+
+using framework::Tensor;
+using framework::LoDTensor;
+
+class DropoutOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+ protected:
+  void InferShape(const framework::InferShapeContext &ctx) const override {
+    PADDLE_ENFORCE_NOT_NULL(ctx.InputVar("X"), "Input(X) must not be null.");
+    PADDLE_ENFORCE_GE(ctx.Attr<float>("dropout_prob"), 0);
+    PADDLE_ENFORCE_LE(ctx.Attr<float>("dropout_prob"), 1);
+    // TODO(xinghai-sun): remove this check after swtiching to bool
+    PADDLE_ENFORCE(ctx.Attr<int>("is_training") == 0 ||
+                   ctx.Attr<int>("is_training") == 1);
+
+    auto dims = ctx.Input<Tensor>("X")->dims();
+    ctx.Output<LoDTensor>("Out")->Resize(dims);
+    if (ctx.Attr<int>("is_training") == 1) {
+      ctx.Output<LoDTensor>("Mask")->Resize(dims);
+    }
+  }
+};
+
+template <typename AttrType>
+class DropoutOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  DropoutOpMaker(framework::OpProto *proto,
+                 framework::OpAttrChecker *op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddAttr<AttrType>("dropout_prob", "Probability of setting units to zero.")
+        .SetDefault(.5f);
+    // TODO(xinghai-sun): use bool for is_training after bool is supported.
+    AddAttr<int>("is_training", "Whether in training phase.").SetDefault(1);
+    AddAttr<int>("seed", "Dropout random seed.").SetDefault(0);
+    AddInput("X", "The input of dropout op.");
+    AddOutput("Out", "The output of dropout op.");
+    AddOutput("Mask", "The random sampled dropout mask.").AsIntermediate();
+
+    AddComment(R"DOC(
+Dropout Operator.
+
+"Dropout" refers to randomly dropping out units in a nerual network. It is a
+regularization technique for reducing overfitting by preventing neuron
+co-adaption during training. The dropout operator randomly set (according to
+the given dropout probability) the outputs of some units to zero, while others
+being set to their inputs.
+)DOC");
+  }
+};
+
+template <typename AttrType>
+class DropoutOpGrad : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+ protected:
+  void InferShape(const framework::InferShapeContext &ctx) const override {
+    PADDLE_ENFORCE_EQ(ctx.Attr<int>("is_training"), 1,
+                      "GradOp is only callable when is_training is true");
+
+    PADDLE_ENFORCE_NOT_NULL(ctx.InputVar("X"), "Input(X) must not be null.");
+    PADDLE_ENFORCE_NOT_NULL(ctx.InputVar("Mask"), "Mask must not be null.");
+    PADDLE_ENFORCE_NOT_NULL(ctx.InputVar(framework::GradVarName("Out")),
+                            "Input(Out@GRAD) must not be null.");
+
+    PADDLE_ENFORCE_GE(ctx.Attr<AttrType>("dropout_prob"), 0);
+    PADDLE_ENFORCE_LE(ctx.Attr<AttrType>("dropout_prob"), 1);
+    // TODO(xinghai-sun): remove this check after swtiching to bool
+    PADDLE_ENFORCE(ctx.Attr<int>("is_training") == 0 ||
+                   ctx.Attr<int>("is_training") == 1);
+    auto x_dims = ctx.Input<Tensor>("X")->dims();
+    auto out_dims = ctx.Input<Tensor>(framework::GradVarName("Out"))->dims();
+    PADDLE_ENFORCE_EQ(x_dims, out_dims,
+                      "Dimensions of Input(X) and Out@Grad must be the same.");
+    auto mask_dims = ctx.Input<Tensor>("Mask")->dims();
+    PADDLE_ENFORCE_EQ(x_dims, mask_dims,
+                      "Dimensions of Input(X) and Mask must be the same.");
+
+    auto *x_grad = ctx.Output<LoDTensor>(framework::GradVarName("X"));
+    x_grad->Resize(x_dims);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+REGISTER_OP(dropout, ops::DropoutOp, ops::DropoutOpMaker<float>, dropout_grad,
+            ops::DropoutOpGrad<float>);
+REGISTER_OP_CPU_KERNEL(
+    dropout, ops::CPUDropoutKernel<paddle::platform::CPUPlace, float, float>);
+REGISTER_OP_CPU_KERNEL(
+    dropout_grad, ops::DropoutGradKernel<paddle::platform::CPUPlace, float>);

paddle/operators/dropout_op.cu

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   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. */
+
+#define EIGEN_USE_GPU
+#include <thrust/device_ptr.h>
+#include <thrust/iterator/counting_iterator.h>
+#include <thrust/random.h>
+#include <thrust/transform.h>
+#include "paddle/operators/dropout_op.h"
+
+namespace paddle {
+namespace operators {
+
+template <typename T, typename AttrType>
+struct MaskGenerator {
+  AttrType dropout_prob;
+  int seed;
+
+  __host__ __device__ MaskGenerator(AttrType dropout_prob, int seed)
+      : dropout_prob(dropout_prob), seed(seed) {}
+
+  __host__ __device__ T operator()(const unsigned int n) const {
+    thrust::minstd_rand rng;
+    rng.seed(seed);
+    thrust::uniform_real_distribution<AttrType> dist(0, 1);
+    rng.discard(n);
+    if (dist(rng) < dropout_prob) {
+      return static_cast<T>(0);
+    } else {
+      return static_cast<T>(1);
+    }
+  }
+};
+
+// It seems that Eigen::Tensor::setRandom in GPU will SEGFAULT.
+// Use std::random and thrust::random(thrust is a std library in CUDA) to
+// implement uniform random.
+template <typename Place, typename T, typename AttrType>
+class GPUDropoutKernel : public framework::OpKernel {
+ public:
+  void Compute(const framework::ExecutionContext& context) const override {
+    auto* x = context.Input<Tensor>("X");
+    auto* y = context.Output<Tensor>("Out");
+    y->mutable_data<T>(context.GetPlace());
+    AttrType dropout_prob = context.Attr<AttrType>("dropout_prob");
+
+    auto X = EigenMatrix<T>::Reshape(*x, 1);
+    auto Y = EigenMatrix<T>::Reshape(*y, 1);
+
+    auto place = context.GetEigenDevice<Place>();
+    if (context.Attr<int>("is_training") == 1) {
+      auto* mask = context.Output<Tensor>("Mask");
+      auto* mask_data = mask->mutable_data<T>(context.GetPlace());
+      int size = framework::product(mask->dims());
+      int seed = context.Attr<int>("seed");
+      thrust::counting_iterator<unsigned int> index_sequence_begin(0);
+      thrust::transform(index_sequence_begin, index_sequence_begin + size,
+                        thrust::device_ptr<T>(mask_data),
+                        MaskGenerator<T, AttrType>(dropout_prob, seed));
+      auto M = EigenMatrix<T>::Reshape(*mask, 1);
+      Y.device(place) = X * M;
+    } else {
+      Y.device(place) = X * dropout_prob;
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+REGISTER_OP_GPU_KERNEL(
+    dropout, ops::GPUDropoutKernel<paddle::platform::GPUPlace, float, float>);
+REGISTER_OP_GPU_KERNEL(
+    dropout_grad, ops::DropoutGradKernel<paddle::platform::GPUPlace, float>);

paddle/operators/dropout_op.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   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. */
+
+#pragma once
+#include <random>
+#include "paddle/framework/eigen.h"
+#include "paddle/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+template <typename T, int MajorType = Eigen::RowMajor,
+          typename IndexType = Eigen::DenseIndex>
+using EigenMatrix = framework::EigenMatrix<T, MajorType, IndexType>;
+
+template <typename Place, typename T, typename AttrType>
+class CPUDropoutKernel : public framework::OpKernel {
+ public:
+  void Compute(const framework::ExecutionContext& context) const override {
+    auto* x = context.Input<Tensor>("X");
+    auto* y = context.Output<Tensor>("Out");
+    const auto* x_data = x->data<T>();
+    auto* y_data = y->mutable_data<T>(context.GetPlace());
+    AttrType dropout_prob = context.Attr<AttrType>("dropout_prob");
+
+    if (context.Attr<int>("is_training") == 1) {
+      auto* mask = context.Output<Tensor>("Mask");
+      auto* mask_data = mask->mutable_data<T>(context.GetPlace());
+      int seed = context.Attr<int>("seed");
+      std::minstd_rand engine;
+      engine.seed(seed);
+      std::uniform_real_distribution<AttrType> dist(0, 1);
+      size_t size = framework::product(mask->dims());
+      for (size_t i = 0; i < size; ++i) {
+        if (dist(engine) < dropout_prob) {
+          mask_data[i] = 0;
+          y_data[i] = 0;
+        } else {
+          mask_data[i] = 1;
+          y_data[i] = x_data[i];
+        }
+      }
+    } else {
+      auto X = EigenMatrix<T>::Reshape(*x, 1);
+      auto Y = EigenMatrix<T>::Reshape(*y, 1);
+      auto place = context.GetEigenDevice<Place>();
+      Y.device(place) = X * dropout_prob;
+    }
+  }
+};
+
+template <typename Place, typename T>
+class DropoutGradKernel : public framework::OpKernel {
+ public:
+  void Compute(const framework::ExecutionContext& context) const override {
+    PADDLE_ENFORCE_EQ(context.Attr<int>("is_training"), 1,
+                      "GradOp is only callable when is_training is true");
+
+    auto* grad_x = context.Output<Tensor>(framework::GradVarName("X"));
+    auto* grad_y = context.Input<Tensor>(framework::GradVarName("Out"));
+    auto* mask = context.Input<Tensor>("Mask");
+    grad_x->mutable_data<T>(context.GetPlace());
+
+    auto M = EigenMatrix<T>::Reshape(*mask, 1);
+    auto dX = EigenMatrix<T>::Reshape(*grad_x, 1);
+    auto dY = EigenMatrix<T>::Reshape(*grad_y, 1);
+
+    auto place = context.GetEigenDevice<Place>();
+    dX.device(place) = dY * M;
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

python/paddle/v2/framework/tests/test_dropout_op.py

+import unittest
+import numpy as np
+from op_test import OpTest
+
+
+class TestDropoutOp(OpTest):
+    def setUp(self):
+        self.op_type = "dropout"
+        self.inputs = {'X': np.random.random((32, 64)).astype("float32")}
+        self.attrs = {'dropout_prob': 0.0, 'is_training': 1}
+        self.outputs = {'Out': self.inputs['X'], 'Mask': np.ones((32, 64))}
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad_normal(self):
+        self.check_grad(['X'], 'Out', max_relative_error=0.05)
+
+
+class TestDropoutOp2(TestDropoutOp):
+    def setUp(self):
+        self.op_type = "dropout"
+        self.inputs = {'X': np.random.random((32, 64)).astype("float32")}
+        self.attrs = {'dropout_prob': 1.0, 'is_training': 1}
+        self.outputs = {'Out': np.zeros((32, 64)), 'Mask': np.zeros((32, 64))}
+
+
+class TestDropoutOp3(TestDropoutOp):
+    def setUp(self):
+        self.op_type = "dropout"
+        self.inputs = {'X': np.random.random((32, 64, 2)).astype("float32")}
+        self.attrs = {'dropout_prob': 0.0, 'is_training': 1}
+        self.outputs = {'Out': self.inputs['X'], 'Mask': np.ones((32, 64, 2))}
+
+
+class TestDropoutOp4(OpTest):
+    def setUp(self):
+        self.op_type = "dropout"
+        self.inputs = {'X': np.random.random((32, 64)).astype("float32")}
+        self.attrs = {'dropout_prob': 0.35, 'is_training': 0}
+        self.outputs = {'Out': self.inputs['X'] * self.attrs['dropout_prob']}
+
+    def test_check_output(self):
+        self.check_output()
+
+
+class TestDropoutOp5(OpTest):
+    def setUp(self):
+        self.op_type = "dropout"
+        self.inputs = {'X': np.random.random((32, 64, 3)).astype("float32")}
+        self.attrs = {'dropout_prob': 0.75, 'is_training': 0}
+        self.outputs = {'Out': self.inputs['X'] * self.attrs['dropout_prob']}
+
+    def test_check_output(self):
+        self.check_output()
+
+
+if __name__ == '__main__':
+    unittest.main()