diff --git a/doc/howto/cross_compiling/cross_compiling_for_raspberry_cn.md b/doc/howto/cross_compiling/cross_compiling_for_raspberry_cn.md
index 085b5dda1615a9af918b59870db460fcc5acdcca..026c0c6f3b2a2ca322d063f38e1736a010e1197e 100644
--- a/doc/howto/cross_compiling/cross_compiling_for_raspberry_cn.md
+++ b/doc/howto/cross_compiling/cross_compiling_for_raspberry_cn.md
@@ -1,39 +1,36 @@
 # 构建Raspberry Pi平台上的PaddlePaddle库
 
-对于Rasspberry Pi系统，用户可通过ssh等方式登录到Raspberry Pi系统上，按照[源码编译PaddlePaddle](http://www.paddlepaddle.org/doc_cn/getstarted/build_and_install/cmake/build_from_source_cn.html)相关文档所述，直接编译Raspberry Pi平台上适用的PaddlePaddle库。
+通常有两个方法来构建基于 Rasspberry Pi 的版本：
 
-用户也可以在自己熟悉的开发平台上，通过交叉编译的方式来编译。这篇文档将以Linux x86-64平台为例，介绍交叉编译Raspberry Pi平台上适用的PaddlePaddle的方法和步骤。
+1. 通过ssh等方式登录到Raspberry Pi系统上来构建。所需的开发工具和第三方库可以参考 [`/Dockerfile`](https://github.com/PaddlePaddle/Paddle/blob/develop/Dockerfile)。
 
-## 准备交叉编译环境
+1. 另一个方法是交叉编译。这篇文档介绍在 Linux/x64 上交叉编译Raspberry Pi平台上适用的PaddlePaddle的方法和步骤。
 
-从源码交叉编译PaddlePaddle，用户需要提前准备好交叉编译环境。用户可自行前往[github](https://github.com/raspberrypi/tools)下载Raspberry Pi平台使用的C/C++交叉编译工具链，也可通过以下命令获取：
+## 安装交叉编译器
+
+克隆下面 Github repo
 
 ```bash
 git clone https://github.com/raspberrypi/tools.git
 ```
 
-该github仓库中包含若干个预编译好的、针对不同平台的编译工具。宿主机是Linux x86-64环境，则需选用`arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64`下的作为编译工具，所使用的编译器为arm-linux-gnueabihf-gcc 4.8.3。
-
-注意，该编译工具链需要系统glibc支持2.14以上。
+即可在 `./tools/tree/master/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64` 目录里找到交叉编译器 arm-linux-gnueabihf-gcc 4.8.3。运行该编译工具链需要一台 Linux x64 机器上以及 2.14版本以上的 glibc。
 
 ## 配置交叉编译参数
 
-CMake系统对交叉编译提供了支持[cmake-toolchains](https://cmake.org/cmake/help/v3.0/manual/cmake-toolchains.7.html#cross-compiling)。为了简化cmake配置，PaddlePaddle为交叉编译提供了工具链配置文档[cmake/cross_compiling/raspberry_pi.cmake](https://github.com/PaddlePaddle/Paddle/blob/develop/cmake/cross_compiling/raspberry_pi.cmake)，以提供一些默认的编译器和编译参数相关配置。
+CMake[支持交叉编译](https://cmake.org/cmake/help/v3.0/manual/cmake-toolchains.7.html#cross-compiling)。PaddlePaddle for Raspberry Pi的配置信息在[cmake/cross_compiling/raspberry_pi.cmake](https://github.com/PaddlePaddle/Paddle/blob/develop/cmake/cross_compiling/raspberry_pi.cmake)。
 
 交叉编译Raspberry Pi版本PaddlePaddle库时，有一些必须配置的参数：
 
-- `CMAKE_SYSTEM_NAME`，CMake编译的目标平台，必须配置为`RPi`。在设置`CMAKE_SYSTEM_NAME=RPi`后，PaddlePaddle的CMake系统才认为在是在交叉编译Raspberry Pi系统的版本，并自动编译宿主机版protoc可执行文件、目标机版protobuf库、以及目标机版OpenBLAS库。
-
-Raspberry Pi平台可选配置参数：
+- `CMAKE_SYSTEM_NAME`：CMake编译的目标平台，必须配置为`RPi`。在设置`CMAKE_SYSTEM_NAME=RPi`后，PaddlePaddle的CMake系统才认为在是在交叉编译Raspberry Pi系统的版本，并自动编译宿主机版protoc可执行文件、目标机版protobuf库、以及目标机版OpenBLAS库。
 
-- `RPI_TOOLCHAIN`，编译工具链所在的绝对路径，或者相对于构建目录的相对路径。PaddlePaddle的CMake系统将根据该值自动设置需要使用的交叉编译器；否则，用户需要在cmake时手动设置这些值。无默认值。
-- `RPI_ARM_NEON`，是否使用NEON指令。目前必须设置成`ON`，默认值为`ON`。
+- `RPI_TOOLCHAIN`：编译工具链所在的绝对路径，或者相对于构建目录的相对路径。PaddlePaddle的CMake系统将根据该值自动设置需要使用的交叉编译器；否则，用户需要在cmake时手动设置这些值。无默认值。
 
-其他配置参数：
+- `RPI_ARM_NEON`：是否使用NEON指令。目前必须设置成`ON`，默认值为`ON`。
 
 - `HOST_C/CXX_COMPILER`，宿主机的C/C++编译器。在编译宿主机版protoc可执行文件和目标机版OpenBLAS库时需要用到。默认设置成环境变量`CC`的值；若环境变量`CC`没有设置，则设置成`cc`编译器。
 
-cmake参数如下；
+一个常用的CMake配置如下：
 
 ```
 cmake -DCMAKE_SYSTEM_NAME=RPi \
@@ -47,7 +44,9 @@ cmake -DCMAKE_SYSTEM_NAME=RPi \
       ..
 ```
 
-用户还可根据自己的需求设置其他编译参数。比如希望最小化生成的库的大小，可以设置`CMAKE_BUILD_TYPE`为`MinSizeRel`；若希望最快的执行速度，则可设置`CMAKE_BUILD_TYPE`为`Release`。亦可以通过手动设置`CMAKE_C/CXX_FLAGS_MINSIZEREL/RELEASE`来影响PaddlePaddle的编译过程。
+其中`WITH_C_API=ON`表示需要构建推理库。
+
+用户还可根据自己的需求设置其他编译参数。比如希望最小化生成的库的大小，可以设置`CMAKE_BUILD_TYPE`为`MinSizeRel`；若希望最快的执行速度，则可设置`CMAKE_BUILD_TYPE`为`Release`。
 
 ## 编译和安装
 
@@ -60,6 +59,4 @@ make install
 
 注意：如果你曾经在源码目录下编译过其他平台的PaddlePaddle库，请先使用`rm -rf`命令删除`third_party`目录和`build`目录，以确保所有的第三方依赖库和PaddlePaddle代码都是针对新的CMake配置重新编译的。
 
-执行完安装命令后，由于上一步cmake配置中`WITH_C_API`设置为`ON`，`your/path/to/install`目录中会包含`include`和`lib`目录，其中`include`中包含C-API的头文件，`lib`中包含一个Raspberry Pi版本的库。
-
-更多的编译配置见[源码编译PaddlePaddle](http://www.paddlepaddle.org/doc_cn/getstarted/build_and_install/cmake/build_from_source_cn.html)相关文档。
+执行完安装命令后，，`your/path/to/install`目录中会包含`include`和`lib`目录，其中`include`中包含C-API的头文件，`lib`中包含一个Raspberry Pi版本的库。
diff --git a/doc/howto/cross_compiling/cross_compiling_for_raspberry_en.md b/doc/howto/cross_compiling/cross_compiling_for_raspberry_en.md
new file mode 100644
index 0000000000000000000000000000000000000000..09ac4733ec98c598dfd62f22beaf838320dc7531
--- /dev/null
+++ b/doc/howto/cross_compiling/cross_compiling_for_raspberry_en.md
@@ -0,0 +1,62 @@
+# Build PaddlePaddle for Raspberry Pi
+
+You may use any of the following two approaches to build the inference library of PaddlePaddle for Raspberry Pi:
+
+1. Build using SSH: Log in to a Raspberry Pi using SSH and build the library. The required development tools and third-party dependencies are listed in here: [`/Dockerfile`](https://github.com/PaddlePaddle/Paddle/blob/develop/Dockerfile).
+
+1. Cross-compile: We talk about how to cross-compile PaddlePaddle for Raspberry Pi on a Linux/x64 machine, in more detail in this article.
+
+## The Cross-Compiling Toolchain
+
+Step 1. Clone the Github repo by running the following command.
+
+```bash
+git clone https://github.com/raspberrypi/tools.git
+```
+
+Step 2. Use the pre-built cross-compiler found in `./tools/tree/master/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64`.  To run it on a Linux computer, glibc version >= 2.14 is needed.
+
+## CMake Arguments
+
+CMake supports [cross-compiling](https://cmake.org/cmake/help/v3.0/manual/cmake-toolchains.7.html#cross-compiling).  All CMake configuration arguments required for the cross-compilation for Raspberry Pi can be found in [`cmake/cross_compiling/raspberry_pi.cmake`](https://github.com/PaddlePaddle/Paddle/blob/develop/cmake/cross_compiling/raspberry_pi.cmake).
+
+Some important arguments that need to be set:
+
+- `CMAKE_SYSTEM_NAME`: The target platform.  Must be `RPi`.
+
+- `RPI_TOOLCHAIN`: The absolute path of the cross-compiling toolchain.
+
+- `RPI_ARM_NEON`: Use ARM NEON Intrinsics. This is a required argument and set default to `ON`.
+
+- `HOST_C/CXX_COMPILER`: The C/C++ compiler for the host.  It is used to build building tools running on the host, for example, protoc.
+
+A commonly-used CMake configuration is as follows:
+
+```
+cmake -DCMAKE_SYSTEM_NAME=RPi \
+      -DRPI_TOOLCHAIN=your/path/to/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64 \
+      -DRPI_ARM_NEON=ON \
+      -DCMAKE_INSTALL_PREFIX=your/path/to/install \
+      -DWITH_GPU=OFF \
+      -DWITH_C_API=ON \
+      -DWITH_PYTHON=OFF \
+      -DWITH_SWIG_PY=OFF \
+      ..
+```
+
+To build the inference library, please set the argument WITH_API to ON: `WITH_C_API=ON`.
+
+You can add more arguments. For example, to minimize the size of the generated inference library, you may use `CMAKE_BUILD_TYPE=MinSizeRel`. For performance optimization, you may use `CMAKE_BUILD_TYPE=Release`.
+
+## Build and Install
+
+The following commands build the inference library of PaddlePaddle for Raspberry Pi and third-party dependencies.
+
+```bash
+make
+make install
+```
+
+ The intermediate files will be stored in `build`. Third-party libraries will be located in `build/third_party`. If you have already built it for other platforms like Android or iOS, you may want to clear these directories by running the command: `rm -rf build`.
+
+The infernece library will be in `your/path/to/install/lib`, with related header files in `your/path/to/install/include`.
diff --git a/go/.gitignore b/go/.gitignore
index 000e1fd55b63b8e532308b787c2708a6c3e5ac87..398d70ca375ffceccdbfc82a4851a6830ca31264 100644
--- a/go/.gitignore
+++ b/go/.gitignore
@@ -1,2 +1,3 @@
 vendor/
 .glide/
+proto/*.go
diff --git a/go/glide.lock b/go/glide.lock
index ce654d36364f8078a493651d8d8b141532eea26d..d15fc934dbe511389cc92ce95cededa41ba32b4d 100644
--- a/go/glide.lock
+++ b/go/glide.lock
@@ -1,5 +1,5 @@
-hash: 51d9e2e46d7fd9173ff11ecada40f7b7728756be18d5e2f032535f66465e6e15
-updated: 2017-10-24T15:04:09.987751592-07:00
+hash: 107c058cf5c9163a75d40eef2273a793c36112683c25d72aa8288827fdde3a19
+updated: 2017-10-30T03:46:19.137696069Z
 imports:
 - name: github.com/alecthomas/gometalinter
   version: bae2f1293d092fd8167939d5108d1b025eaef9de
diff --git a/go/glide.yaml b/go/glide.yaml
index ba253f8bebef0ddab810a8303ab1fbe541defbdf..c5d66694acd0f45de5002391a7953b7491eaf2bc 100644
--- a/go/glide.yaml
+++ b/go/glide.yaml
@@ -30,3 +30,4 @@ import:
   version: v2.13
 - package: github.com/go-stack/stack
   version: v1.6.0
+- package: github.com/golang/protobuf
diff --git a/go/proto/.gitignore b/go/proto/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..5e7d2734cfc60289debf74293817c0a8f572ff32
--- /dev/null
+++ b/go/proto/.gitignore
@@ -0,0 +1,4 @@
+# Ignore everything in this directory
+*
+# Except this file
+!.gitignore
diff --git a/go/pserver/CMakeLists.txt b/go/pserver/CMakeLists.txt
index 4fe0a8cb021e8dbf443c8f33bfb046e228a2fd8d..9ac05199e7ab76c21275838092c0afbdf2612b77 100644
--- a/go/pserver/CMakeLists.txt
+++ b/go/pserver/CMakeLists.txt
@@ -13,5 +13,5 @@
 # limitations under the License.
 #
 if(WITH_TESTING)
-  go_test(pserver_test DEPS paddle_go_optimizer)
+  go_test(pserver_test DEPS paddle_go_optimizer gen_proto_go)
 endif()
diff --git a/go/pserver/service.go b/go/pserver/service.go
index f703d99a29ae9f5310ef36a7492b729c4c892937..7484ec90b1a3a9e67fa798741a9dfeb580c51f1a 100644
--- a/go/pserver/service.go
+++ b/go/pserver/service.go
@@ -17,6 +17,7 @@ package pserver
 import (
 	"bufio"
 	"bytes"
+	"encoding/binary"
 	"encoding/gob"
 	"encoding/json"
 	"errors"
@@ -26,11 +27,15 @@ import (
 	"os"
 	"path"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
+	"github.com/golang/protobuf/proto"
 	uuid "github.com/satori/go.uuid"
 
+	pb "github.com/PaddlePaddle/Paddle/go/proto"
+
 	log "github.com/inconshreveable/log15"
 )
 
@@ -65,6 +70,46 @@ type Parameter struct {
 	Content     []byte
 }
 
+func float32ToString(b []byte) string {
+	f := make([]float32, len(b)/4)
+	buf := bytes.NewReader(b)
+	err := binary.Read(buf, binary.LittleEndian, &f)
+	if err != nil {
+		return ""
+	}
+	return fmt.Sprintf("%v", f)
+}
+
+func float32ByteToString(c []byte) string {
+	var a []byte
+	var b []byte
+	if len(c) <= 80 {
+		a = c
+	} else {
+		a = c[0:40]
+		b = c[len(c)-40:]
+	}
+
+	var s string
+	s = float32ToString(a)
+
+	if b == nil {
+		return s
+	}
+
+	s = strings.Replace(s, "]", "", -1) + "..." + strings.Replace(float32ToString(b), "[", "", -1)
+	return s
+}
+
+func (p Parameter) String() string {
+	if p.ElementType != Float32 {
+		return fmt.Sprintf("name:%v ElementType:%v",
+			p.Name, p.ElementType)
+	}
+
+	return float32ByteToString(p.Content)
+}
+
 // ParameterWithConfig contains the parameter and the configuration.
 type ParameterWithConfig struct {
 	Param  Parameter
@@ -189,7 +234,9 @@ func (s *Service) InitParam(paramWithConfigs ParameterWithConfig, _ *int) error
 	default:
 	}
 
-	// TODO(helin): parse parameter config
+	c := &pb.OptimizerConfig{}
+	proto.Unmarshal(paramWithConfigs.Config, c)
+	log.Debug(fmt.Sprintf("OptimizerConfig:%v", c))
 
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -239,7 +286,8 @@ func (s *Service) SendGrad(g Gradient, _ *int) error {
 	select {
 	case <-s.initialized:
 	default:
-		log.Warn("received gradient before initialization.", "name", g.Name, "size", len(g.Content), "type", g.ElementType)
+		log.Warn("received gradient before initialization.",
+			"name", g.Name, "size", len(g.Content), "type", g.ElementType)
 		return errors.New(Uninitialized)
 	}
 
@@ -248,10 +296,14 @@ func (s *Service) SendGrad(g Gradient, _ *int) error {
 
 	o, ok := s.optMap[g.Name]
 	if !ok {
+		log.Warn("received gradient but can't find name.",
+			"name", g.Name, "size", len(g.Content), "type", g.ElementType)
 		return fmt.Errorf("parameter: %s does not exist", g.Name)
 	}
 
-	log.Info("received gradient from trainer, updating gradient.", "name", g.Name, "size", len(g.Content), "type", g.ElementType)
+	log.Debug(Parameter(g).String())
+	log.Info("received gradient from trainer, updating gradient.",
+		"name", g.Name, "size", len(g.Content), "type", g.ElementType)
 	return o.UpdateParameter(g)
 }
 
@@ -277,7 +329,7 @@ func (s *Service) GetParam(name string, parameter *Parameter) error {
 	parameter.Name = name
 	parameter.ElementType = opt.elementType
 	parameter.Content = opt.GetWeights()
-
+	log.Debug(parameter.String())
 	log.Info("sending parameter to the trainer", "name", parameter.Name, "size", len(parameter.Content), "type", parameter.ElementType)
 	return nil
 }
diff --git a/go/pserver/service_test.go b/go/pserver/service_test.go
index b6f4566eb78cf797e3738afa5f86f5c4e8090d85..58a743e1fadff9d629f682d660e661013c33ac8a 100644
--- a/go/pserver/service_test.go
+++ b/go/pserver/service_test.go
@@ -15,6 +15,7 @@
 package pserver_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"reflect"
 	"sync"
@@ -178,3 +179,33 @@ func TestBlockUntilInitialized(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestGradientString(t *testing.T) {
+	g := pserver.Parameter{}
+	g.ElementType = pserver.Float32
+	g.Content = []byte{0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40, 0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40}
+	if g.String() != "[3.3702806e+12 2.142699 3.3702806e+12 2.142699]" {
+		t.Fatal("get float data error!")
+	}
+
+	g.Content = []byte{0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
+		0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40}
+	if g.String() != "[3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699...3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699 3.3702806e+12 2.142699]" {
+		t.Fatal("get float data error!", g.String())
+	}
+	fmt.Println(g)
+}
diff --git a/paddle/operators/accuracy_op.cc b/paddle/operators/accuracy_op.cc
index eb8bce8da70a128bd1e0d36540dce5e296540629..88958e1634c51c5d217c22333f2aaf4a5adf89fd 100644
--- a/paddle/operators/accuracy_op.cc
+++ b/paddle/operators/accuracy_op.cc
@@ -32,7 +32,8 @@ class AccuracyOp : public framework::OperatorWithKernel {
     auto inference_dim = ctx->GetInputDim("Inference");
     auto label_dim = ctx->GetInputDim("Label");
 
-    PADDLE_ENFORCE_EQ(label_dim.size(), 1, "label must be a vector");
+    PADDLE_ENFORCE_EQ(label_dim.size(), 2, "label's rank must be 2.");
+    PADDLE_ENFORCE_EQ(label_dim[1], 1, "label's second dimension must be 1");
     PADDLE_ENFORCE_EQ(inference_dim[0], label_dim[0],
                       "inference size must be the same as label size");
 
@@ -68,7 +69,8 @@ information, or not. But the output only shares the LoD with input `Inference`.
 }  // namespace paddle
 
 namespace ops = paddle::operators;
-REGISTER_OP_WITHOUT_GRADIENT(accuracy, ops::AccuracyOp, ops::AccuracyOpMaker);
+REGISTER_OPERATOR(accuracy, ops::AccuracyOp, ops::AccuracyOpMaker,
+                  paddle::framework::EmptyGradOpMaker);
 REGISTER_OP_CPU_KERNEL(
     accuracy, ops::AccuracyKernel<paddle::platform::CPUPlace, int>,
     ops::AccuracyKernel<paddle::platform::CPUPlace, int64_t>);
diff --git a/paddle/operators/activation_op.h b/paddle/operators/activation_op.h
index e4c6b2e09cd71f00a2ef73173205b9066c34fcf5..ddd966e26c9abad0d83f8b5c6e3e7d9ad65158a8 100644
--- a/paddle/operators/activation_op.h
+++ b/paddle/operators/activation_op.h
@@ -547,6 +547,7 @@ struct ELUGradFunctor : public BaseActivationFunctor<T> {
   }
 };
 
+// FIXME(qijun) https://github.com/PaddlePaddle/Paddle/issues/5198
 template <typename T>
 struct PowFunctor : public BaseActivationFunctor<T> {
   float factor;
diff --git a/paddle/operators/top_k_op.cc b/paddle/operators/top_k_op.cc
index d5c2c91a5fb0f639ea84d13e27de8271218da54f..ac9257259548dc4223efac239d8362f69366850c 100644
--- a/paddle/operators/top_k_op.cc
+++ b/paddle/operators/top_k_op.cc
@@ -52,7 +52,11 @@ class TopkOpMaker : public framework::OpProtoAndCheckerMaker {
     AddOutput("Out", "The output tensor of Topk op");
     AddOutput("Indices", "The indices of Topk elements of input");
     AddComment(
-        R"DOC(If the input is a vector (1d tensor), finds the k largest entries in the vector and outputs their values and indices as vectors. Thus values[j] is the j-th largest entry in input, and its index is indices[j].
+        R"DOC(If the input is a vector (1d tensor), 
+        finds the k largest entries in the vector 
+        and outputs their values and indices as vectors. 
+        Thus values[j] is the j-th largest entry in input, 
+        and its index is indices[j].
 
     For matrices, computes the top k entries in each row. )DOC");
     AddAttr<int>("k",
@@ -66,6 +70,7 @@ class TopkOpMaker : public framework::OpProtoAndCheckerMaker {
 }  // namespace paddle
 
 namespace ops = paddle::operators;
-REGISTER_OP_WITHOUT_GRADIENT(top_k, ops::TopkOp, ops::TopkOpMaker);
+REGISTER_OPERATOR(top_k, ops::TopkOp, ops::TopkOpMaker,
+                  paddle::framework::EmptyGradOpMaker);
 REGISTER_OP_CPU_KERNEL(top_k,
                        ops::TopkKernel<paddle::platform::CPUPlace, float>);
diff --git a/paddle/platform/CMakeLists.txt b/paddle/platform/CMakeLists.txt
index eb850b658583f2256629d63fdb64248dbf249937..bd86a9fe268c277065cd450f91b544def6c4d32f 100644
--- a/paddle/platform/CMakeLists.txt
+++ b/paddle/platform/CMakeLists.txt
@@ -9,7 +9,6 @@ cc_test(place_test SRCS place_test.cc DEPS place glog gflags)
 add_subdirectory(dynload)
 
 cc_test(enforce_test SRCS enforce_test.cc DEPS stringpiece)
-cc_test(environment_test SRCS environment_test.cc DEPS stringpiece)
 
 IF(WITH_GPU)
     set(GPU_CTX_DEPS dynload_cuda dynamic_loader)
diff --git a/paddle/platform/environment.h b/paddle/platform/environment.h
deleted file mode 100644
index 4edcce932edc61453cef74f2c4ee0f72496b3677..0000000000000000000000000000000000000000
--- a/paddle/platform/environment.h
+++ /dev/null
@@ -1,60 +0,0 @@
-/* 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 <stdlib.h>
-#include <unistd.h>
-#include <vector>
-
-#include "paddle/platform/enforce.h"
-#include "paddle/string/piece.h"
-
-extern char** environ;  // for environment variables
-
-namespace paddle {
-namespace platform {
-
-inline void SetEnvVariable(const std::string& name, const std::string& value) {
-  PADDLE_ENFORCE_NE(setenv(name.c_str(), value.c_str(), 1), -1,
-                    "Failed to set environment variable %s=%s", name, value);
-}
-
-inline void UnsetEnvVariable(const std::string& name) {
-  PADDLE_ENFORCE_NE(unsetenv(name.c_str()), -1,
-                    "Failed to unset environment variable %s", name);
-}
-
-inline bool IsEnvVarDefined(const std::string& name) {
-  return std::getenv(name.c_str()) != nullptr;
-}
-
-inline std::string GetEnvValue(const std::string& name) {
-  PADDLE_ENFORCE(IsEnvVarDefined(name),
-                 "Tried to access undefined environment variable %s", name);
-  return std::getenv(name.c_str());
-}
-
-inline std::vector<std::string> GetAllEnvVariables() {
-  std::vector<std::string> vars;
-  for (auto var = environ; *var != nullptr; ++var) {
-    auto tail = string::Index(*var, "=");
-    auto name = string::SubStr(*var, 0, tail).ToString();
-    vars.push_back(name);
-  }
-  return vars;
-}
-
-}  // namespace platform
-}  // namespace paddle
diff --git a/paddle/platform/environment_test.cc b/paddle/platform/environment_test.cc
deleted file mode 100644
index 5f136527215d6a676cfa1a3b08f09dfd3ab24a90..0000000000000000000000000000000000000000
--- a/paddle/platform/environment_test.cc
+++ /dev/null
@@ -1,54 +0,0 @@
-/* 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/platform/environment.h"
-
-#include "glog/logging.h"
-#include "gtest/gtest.h"
-
-TEST(ENVIRONMENT, ACCESS) {
-  namespace platform = paddle::platform;
-  namespace string = paddle::string;
-
-  platform::SetEnvVariable("PADDLE_USE_ENV", "TRUE");
-
-  EXPECT_TRUE(platform::IsEnvVarDefined("PADDLE_USE_ENV"));
-  EXPECT_EQ(platform::GetEnvValue("PADDLE_USE_ENV"), "TRUE");
-
-  platform::UnsetEnvVariable("PADDLE_USE_ENV");
-  EXPECT_FALSE(platform::IsEnvVarDefined("PADDLE_USE_ENV"));
-
-  platform::SetEnvVariable("PADDLE_USE_ENV1", "Hello ");
-  platform::SetEnvVariable("PADDLE_USE_ENV2", "World, ");
-  platform::SetEnvVariable("PADDLE_USE_ENV3", "PaddlePaddle!");
-
-  std::string env_info;
-  auto vars = platform::GetAllEnvVariables();
-  for_each(vars.begin(), vars.end(), [&](const std::string& var) {
-    env_info += platform::GetEnvValue(var);
-  });
-
-  EXPECT_TRUE(string::Contains(env_info, "Hello World, PaddlePaddle!"));
-  platform::UnsetEnvVariable("PADDLE_USE_ENV1");
-  platform::UnsetEnvVariable("PADDLE_USE_ENV2");
-  platform::UnsetEnvVariable("PADDLE_USE_ENV3");
-
-  env_info.clear();
-  vars = platform::GetAllEnvVariables();
-  for_each(vars.begin(), vars.end(), [&](const std::string& var) {
-    env_info += platform::GetEnvValue(var);
-  });
-
-  EXPECT_FALSE(string::Contains(env_info, "Hello World, PaddlePaddle!"));
-  EXPECT_FALSE(platform::IsEnvVarDefined("PADDLE_USE_ENV1"));
-  EXPECT_FALSE(platform::IsEnvVarDefined("PADDLE_USE_ENV2"));
-  EXPECT_FALSE(platform::IsEnvVarDefined("PADDLE_USE_ENV3"));
-}
diff --git a/paddle/platform/gpu_info.cc b/paddle/platform/gpu_info.cc
index 0cab5ffc5609bbd6fd08c74329d8370fb95f8102..f3455a8733862c91eaece629b6684d446672336c 100644
--- a/paddle/platform/gpu_info.cc
+++ b/paddle/platform/gpu_info.cc
@@ -17,7 +17,6 @@ limitations under the License. */
 #include "gflags/gflags.h"
 
 #include "paddle/platform/enforce.h"
-#include "paddle/platform/environment.h"
 
 DEFINE_double(fraction_of_gpu_memory_to_use, 0.95,
               "Default use 95% of GPU memory for PaddlePaddle,"
@@ -75,13 +74,6 @@ size_t GpuMaxChunkSize() {
 
   GpuMemoryUsage(available, total);
 
-  if (IsEnvVarDefined(kEnvFractionGpuMemoryToUse)) {
-    auto val = std::stod(GetEnvValue(kEnvFractionGpuMemoryToUse));
-    PADDLE_ENFORCE_GT(val, 0.0);
-    PADDLE_ENFORCE_LE(val, 1.0);
-    FLAGS_fraction_of_gpu_memory_to_use = val;
-  }
-
   // Reserving the rest memory for page tables, etc.
   size_t reserving = (1 - FLAGS_fraction_of_gpu_memory_to_use) * total;
 
diff --git a/paddle/pybind/pybind.cc b/paddle/pybind/pybind.cc
index 4baff895daa1f26fe3f344372f2686fbcbb82098..2a0075356ed1e0f0b3501ac681c5e3a1bf37e2ca 100644
--- a/paddle/pybind/pybind.cc
+++ b/paddle/pybind/pybind.cc
@@ -15,6 +15,7 @@ limitations under the License. */
 #include "paddle/pybind/protobuf.h"
 
 #include <mutex>  // for call_once
+#include <unordered_map>
 #include "gflags/gflags.h"
 #include "paddle/framework/backward.h"
 #include "paddle/framework/executor.h"
@@ -42,9 +43,9 @@ limitations under the License. */
 
 namespace paddle {
 namespace pybind {
-static size_t UniqueIntegerGenerator() {
-  static std::atomic<size_t> generator;
-  return generator.fetch_add(1);
+static size_t UniqueIntegerGenerator(const std::string &prefix) {
+  static std::unordered_map<std::string, std::atomic<size_t>> generators;
+  return generators[prefix].fetch_add(1);
 }
 
 std::once_flag gflags_init_flag;
diff --git a/proto/CMakeLists.txt b/proto/CMakeLists.txt
index 5d898d860cfc6dc26eaf5a81d8aed6d757ed5831..556bcd1d7e60c27fece43de666e9531ab4203414 100644
--- a/proto/CMakeLists.txt
+++ b/proto/CMakeLists.txt
@@ -27,3 +27,30 @@ foreach(filename ${proto_filenames})
 endforeach()
 
 add_custom_target(gen_proto_py ALL DEPENDS ${PROTO_GEN_PY})
+
+
+if (WITH_GOLANG)
+    add_custom_target(protoc-gen-go)
+    add_custom_command(TARGET protoc-gen-go
+            COMMAND go 
+            ARGS "get" "-u" "github.com/golang/protobuf/protoc-gen-go")
+
+    set(PROTO_GEN_GO)
+    file(GLOB proto_filenames . OptimizerConfig.proto)
+    foreach(filename ${proto_filenames})
+        message(STATUS ${filename})
+        get_filename_component(ABS_FIL ${filename} ABSOLUTE)
+        get_filename_component(FIL_WE ${filename} NAME_WE)
+        set(CUR_PROTO_GEN_GO
+                ${PADDLE_SOURCE_DIR}/paddle/go/proto/${FIL_WE}.pb.go)
+        set(PROTO_GEN_GO
+                ${CUR_PROTO_GEN_GO}
+                ${PROTO_GEN_GO})
+        add_custom_command(OUTPUT ${CUR_PROTO_GEN_GO}
+                COMMAND ${PROTOBUF_PROTOC_EXECUTABLE}
+                ARGS "--go_out=${PADDLE_SOURCE_DIR}/go/proto"
+                "-I" ${CMAKE_CURRENT_SOURCE_DIR} ${ABS_FIL}
+                DEPENDS ${ABS_FIL} protoc protoc-gen-go)
+    endforeach()
+    add_custom_target(gen_proto_go ALL DEPENDS ${PROTO_GEN_GO})
+endif()
diff --git a/python/paddle/v2/framework/framework.py b/python/paddle/v2/framework/framework.py
index 43101c9ddad76b7c1c322130dc0362a5c8ea4336..f8d2f67410a6c06a1642180d2d62c881ec6bda3d 100644
--- a/python/paddle/v2/framework/framework.py
+++ b/python/paddle/v2/framework/framework.py
@@ -119,8 +119,9 @@ class Variable(object):
 
     @staticmethod
     def _unique_var_name_():
-        uid = core.unique_integer()  # unique during whole process.
-        return "_generated_var_%d" % uid
+        prefix = "_generated_var"
+        uid = core.unique_integer(prefix)  # unique during whole process.
+        return "_".join([prefix, str(uid)])
 
     @staticmethod
     def _convert_np_dtype_to_dtype_(np_dtype):
diff --git a/python/paddle/v2/framework/layer_helper.py b/python/paddle/v2/framework/layer_helper.py
index 1f72c9bc7b0ceda1dd954703fcc10c77a3e5ed25..d96dbe172c22617182e7ebf4aab175c6142352b7 100644
--- a/python/paddle/v2/framework/layer_helper.py
+++ b/python/paddle/v2/framework/layer_helper.py
@@ -8,7 +8,7 @@ from paddle.v2.framework.framework import Variable, g_program, \
 
 
 def unique_name(prefix):
-    uid = core.unique_integer()  # unique during whole process.
+    uid = core.unique_integer(prefix)  # unique during whole process.
     return "_".join([prefix, str(uid)])
 
 
diff --git a/python/paddle/v2/framework/layers.py b/python/paddle/v2/framework/layers.py
index 57723c4d5aa09a6756b2959aa45e716d1c1dc140..4727d139a28541e06a2dcbcb7bf28510ee123775 100644
--- a/python/paddle/v2/framework/layers.py
+++ b/python/paddle/v2/framework/layers.py
@@ -5,7 +5,7 @@ import re
 
 __all__ = [
     'fc', 'data', 'cross_entropy', 'conv2d', 'pool2d', 'embedding', 'concat',
-    'StaticRNN', 'cast', 'sequence_conv', 'sequence_pool'
+    'StaticRNN', 'cast', 'sequence_conv', 'sequence_pool', 'accuracy'
 ]
 
 
@@ -225,13 +225,30 @@ def square_error_cost(input, label, **kwargs):
 
     square_out = helper.create_tmp_variable(dtype=input.data_type)
     helper.append_op(
-        type='pow',
-        inputs={'X': [minus_out]},
-        outputs={'Y': [square_out]},
-        attrs={'factor': 2.0})
+        type='square', inputs={'X': [minus_out]}, outputs={'Y': [square_out]})
     return square_out
 
 
+def accuracy(input, label, k=1, **kwargs):
+    helper = LayerHelper("accuracy", **kwargs)
+    topk_out = helper.create_tmp_variable(dtype=input.data_type)
+    topk_indices = helper.create_tmp_variable(dtype="int64")
+    helper.append_op(
+        type="top_k",
+        inputs={"X": [input]},
+        outputs={"Out": [topk_out],
+                 "Indices": [topk_indices]},
+        attrs={"k": k})
+    acc_out_dtype = kwargs.get("out_dtype", "float32")
+    acc_out = helper.create_tmp_variable(dtype=acc_out_dtype)
+    helper.append_op(
+        type="accuracy",
+        inputs={"Inference": [topk_indices],
+                "Label": [label]},
+        outputs={"Accuracy": [acc_out]})
+    return acc_out
+
+
 def sequence_conv(input,
                   num_filters,
                   name=None,
diff --git a/python/paddle/v2/framework/tests/op_test.py b/python/paddle/v2/framework/tests/op_test.py
index 50360e6e729df2957a5c7fe871100b5a53bd9305..2e6710b5fcfe5a531067498e38a4cb93d3165602 100644
--- a/python/paddle/v2/framework/tests/op_test.py
+++ b/python/paddle/v2/framework/tests/op_test.py
@@ -281,7 +281,8 @@ class OpTest(unittest.TestCase):
                                          type(sub_out))
                 for sub_out_name, expect in sub_out:
                     idx = find_actual(sub_out_name, fetch_list)
-                    actual_t = np.array(outs[idx])
+                    actual = outs[idx]
+                    actual_t = np.array(actual)
                     expect_t = expect[0] \
                         if isinstance(expect, tuple) else expect
                     self.assertTrue(
@@ -291,11 +292,12 @@ class OpTest(unittest.TestCase):
                         str(place))
                     if isinstance(expect, tuple):
                         self.assertListEqual(
-                            actual_t.lod(), expect[1], "Output (" + sub_out_name
-                            + ") has different lod at " + str(place))
+                            actual.lod(), expect[1], "Output (" + sub_out_name +
+                            ") has different lod at " + str(place))
             else:
                 idx = find_actual(out_name, fetch_list)
-                actual_t = outs[idx]
+                actual = outs[idx]
+                actual_t = np.array(actual)
                 expect = self.outputs[out_name]
                 expect_t = expect[0] if isinstance(expect, tuple) else expect
                 self.assertTrue(
@@ -303,7 +305,7 @@ class OpTest(unittest.TestCase):
                         actual_t, expect_t, atol=atol),
                     "Output (" + out_name + ") has diff at " + str(place))
                 if isinstance(expect, tuple):
-                    self.assertListEqual(actual_t.lod(), expect[1],
+                    self.assertListEqual(actual.lod(), expect[1],
                                          "Output (" + out_name +
                                          ") has different lod at " + str(place))
 
diff --git a/python/paddle/v2/framework/tests/test_accuracy_op.py b/python/paddle/v2/framework/tests/test_accuracy_op.py
index 02be9a02910bee3eae63e12cceaa51cf53591539..f17edd44aefa870ce704552077d91e661a9167de 100644
--- a/python/paddle/v2/framework/tests/test_accuracy_op.py
+++ b/python/paddle/v2/framework/tests/test_accuracy_op.py
@@ -8,12 +8,12 @@ class TestAccuracyOp(OpTest):
         self.op_type = "accuracy"
         n = 8192
         infer = np.random.randint(0, 2, (n, 1)).astype("int")
-        label = np.random.randint(0, 2, (n, )).astype("int")
+        label = np.random.randint(0, 2, (n, 1)).astype("int")
         self.inputs = {'Inference': infer, "Label": label}
         num_correct = 0
         for rowid in xrange(n):
             for ele in infer[rowid]:
-                if ele == label[rowid]:
+                if ele == label[rowid][0]:
                     num_correct += 1
                     break
         self.outputs = {
diff --git a/python/paddle/v2/framework/tests/test_image_classification_layer.py b/python/paddle/v2/framework/tests/test_image_classification_layer.py
index 7411689b615aeaa900fecb8c5ae00cf92203289c..b4eda13552e60f009ec910e3d21e9d77107133a1 100644
--- a/python/paddle/v2/framework/tests/test_image_classification_layer.py
+++ b/python/paddle/v2/framework/tests/test_image_classification_layer.py
@@ -37,7 +37,7 @@ class TestLayer(unittest.TestCase):
         layers.batch_norm(
             input=images, program=program, init_program=init_program)
 
-        #print str(program)
+        # print str(program)
 
     def test_dropout_layer(self):
         program = Program()
@@ -53,7 +53,7 @@ class TestLayer(unittest.TestCase):
             program=program,
             init_program=init_program)
 
-        #print str(program)
+        # print str(program)
 
     def test_img_conv_group(self):
         program = Program()
diff --git a/python/paddle/v2/framework/tests/test_recognize_digits_conv.py b/python/paddle/v2/framework/tests/test_recognize_digits_conv.py
index a9b6c8410e2af36e6928b2fac919398473611728..92b1d0542619b765cc32c98f59604cfc73d7d6d4 100644
--- a/python/paddle/v2/framework/tests/test_recognize_digits_conv.py
+++ b/python/paddle/v2/framework/tests/test_recognize_digits_conv.py
@@ -51,12 +51,14 @@ predict = layers.fc(input=conv_pool_2,
 cost = layers.cross_entropy(
     input=predict, label=label, program=program, init_program=init_program)
 avg_cost = layers.mean(x=cost, program=program)
+accuracy = layers.accuracy(
+    input=predict, label=label, program=program, init_program=init_program)
 
 sgd_optimizer = optimizer.SGDOptimizer(learning_rate=0.001)
 opts = sgd_optimizer.minimize(avg_cost)
 
 BATCH_SIZE = 50
-PASS_NUM = 1
+PASS_NUM = 3
 train_reader = paddle.batch(
     paddle.reader.shuffle(
         paddle.dataset.mnist.train(), buf_size=500),
@@ -83,10 +85,11 @@ for pass_id in range(PASS_NUM):
         outs = exe.run(program,
                        feed={"pixel": tensor_img,
                              "label": tensor_y},
-                       fetch_list=[avg_cost])
-
+                       fetch_list=[avg_cost, accuracy])
         loss = np.array(outs[0])
+        acc = np.array(outs[1])
 
-        if loss < 10.0:
-            exit(0)  # if avg cost less than 10.0, we think our code is good.
+        if loss < 10.0 and acc > 0.9:
+            # if avg cost less than 10.0 and accuracy is larger than 0.9, we think our code is good.
+            exit(0)
 exit(1)
diff --git a/python/paddle/v2/trainer.py b/python/paddle/v2/trainer.py
index b68fd0d5a97a7993ddd0a1d947304fa5428c01b8..db01ab7374eca18b6063dc634da5ef83c4bc9adc 100644
--- a/python/paddle/v2/trainer.py
+++ b/python/paddle/v2/trainer.py
@@ -205,7 +205,8 @@ class SGD(object):
         """
         Testing method. Will test input data.
 
-        :param reader: A reader that reads and yeilds data items.
+        :param reader: A batch reader that reads and yeilds data items,
+                       it should be a paddle.v2.batch.
         :type reader: collections.Iterable
         :param feeding: Feeding is a map of neural network input name and array
                         index that reader returns.