diff --git a/cmake/generic.cmake b/cmake/generic.cmake
index f1d3bb4811376a02f50904196461c2b420b26625..f568b23c8a2aad24ef58645f3601274dfdc7d01a 100644
--- a/cmake/generic.cmake
+++ b/cmake/generic.cmake
@@ -93,6 +93,7 @@ include_directories(${CMAKE_CURRENT_BINARY_DIR})
 if(NOT APPLE)
     find_package(Threads REQUIRED)
     link_libraries(${CMAKE_THREAD_LIBS_INIT})
+    set(CMAKE_CXX_LINK_EXECUTABLE "${CMAKE_CXX_LINK_EXECUTABLE} -ldl")
 endif(NOT APPLE)
 
 function(merge_static_libs TARGET_NAME)
@@ -103,6 +104,7 @@ function(merge_static_libs TARGET_NAME)
   foreach(lib ${libs})
     list(APPEND libs_deps ${${lib}_LIB_DEPENDS})
   endforeach()
+  list(REMOVE_DUPLICATES libs_deps)
 
   if(APPLE) # Use OSX's libtool to merge archives
     # To produce a library we need at least one source file.
diff --git a/go/cmd/pserver/pserver.go b/go/cmd/pserver/pserver.go
index 31ef450f032f756fb32a0444a7e94a18ec2918a0..0ecb1242c3c3d5246125c9ce946001ccf9cbec24 100644
--- a/go/cmd/pserver/pserver.go
+++ b/go/cmd/pserver/pserver.go
@@ -20,6 +20,8 @@ func main() {
 		"comma separated endpoint string for pserver to connect to etcd")
 	etcdTimeout := flag.Int("etcd-timeout", 5, "timeout for etcd calls")
 	numPservers := flag.Int("num-pservers", 1, "total pserver count in a training job")
+	checkpointPath := flag.String("checkpoint-path", "/checkpoints/", "save checkpoint path")
+	checkpointInterval := flag.Int("checkpoint-interval", 600, "save checkpoint per interval seconds")
 	logLevel := flag.String("log-level", "info",
 		"log level, possible values: debug, info, warning, error, fatal, panic")
 	flag.Parse()
@@ -31,18 +33,20 @@ func main() {
 	log.SetLevel(level)
 
 	var idx int
+	var cp pserver.Checkpoint
+	var e *pserver.EtcdClient
 	if *index >= 0 {
 		idx = *index
 	} else {
 		timeout := time.Second * time.Duration((*etcdTimeout))
-		e := pserver.NewEtcdClient(*etcdEndpoint, *numPservers, timeout)
+		e = pserver.NewEtcdClient(*etcdEndpoint, *numPservers, timeout)
 		idx, err = e.Register()
 		if err != nil {
 			panic(err)
 		}
 	}
 
-	s, err := pserver.NewService(idx)
+	s, err := pserver.NewService(idx, *checkpointInterval, *checkpointPath, e, cp)
 	if err != nil {
 		panic(err)
 	}
diff --git a/go/pserver/etcd_client.go b/go/pserver/etcd_client.go
index 37b8d522c1bd07acb41b9515a6d9bc15eae9aa32..1f77787150d16052e3588e9c1795c8d5dafa08e6 100644
--- a/go/pserver/etcd_client.go
+++ b/go/pserver/etcd_client.go
@@ -18,6 +18,8 @@ const (
 	PsDesired = "/ps_desired"
 	// PsAddr is the base dir for pserver to store their addr
 	PsPath = "/ps/"
+	// PsCheckpoint is the etcd path for store checkpoints information
+	PsCheckpoint = "/checkpoints/"
 )
 
 // EtcdClient is the etcd client that the pserver uses for fault
@@ -186,3 +188,14 @@ func (e *EtcdClient) registerPserverEtcd(ctx context.Context) (int, error) {
 
 	return idx, nil
 }
+
+// PutKey put into etcd with value by key specified
+func (e *EtcdClient) PutKey(key string, value []byte, timeout int) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(timeout))
+	_, err := e.etcdClient.Put(ctx, key, string(value))
+	cancel()
+	if err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/go/pserver/optimizer.go b/go/pserver/optimizer.go
index 54d108209402c27e79a9948f60ecbdadeffc7d9b..2d7882d1a75ef55df4a1ec81a8606cd84334fa64 100644
--- a/go/pserver/optimizer.go
+++ b/go/pserver/optimizer.go
@@ -35,22 +35,28 @@ func cArrayToSlice(p unsafe.Pointer, len int) []byte {
 	return (*[1 << 30]byte)(p)[:len:len]
 }
 
-func newOptimizer(paramWithConfigs ParameterWithConfig) *optimizer {
+func newOptimizer(paramWithConfigs ParameterWithConfig, State []byte) *optimizer {
 	o := &optimizer{}
 	o.elementType = paramWithConfigs.Param.ElementType
 	p := paramWithConfigs.Param
 	c := paramWithConfigs.Config
+	s := State
 	log.WithFields(log.Fields{
 		"ElementType": p.ElementType,
 		"ParamSize":   len(p.Content),
 		"ConfigSize":  len(c),
+		"StateSize":   len(s),
 	}).Info("New Optimizer Created with config:")
 	var cbuffer unsafe.Pointer
 	cbuffer = C.malloc(C.size_t(len(p.Content)))
 	C.memcpy(cbuffer, unsafe.Pointer(&p.Content[0]), C.size_t(len(p.Content)))
+	var cstate unsafe.Pointer
+	if len(s) != 0 {
+		cstate = unsafe.Pointer(&s[0])
+	}
+
 	o.opt = C.paddle_create_optimizer((*C.uchar)(&c[0]), C.int(len(c)),
-		C.paddle_element_type(p.ElementType), cbuffer, C.int(len(p.Content)/C.sizeof_float),
-		(*C.char)(nullPtr), 0)
+		C.paddle_element_type(p.ElementType), cbuffer, C.int(len(p.Content)/C.sizeof_float), (*C.char)(cstate), C.int(len(s)))
 	return o
 }
 
@@ -60,6 +66,12 @@ func (o *optimizer) GetWeights() []byte {
 	return cArrayToSlice(buffer, int(bufferLen)*C.sizeof_float)
 }
 
+func (o *optimizer) GetStates() []byte {
+	var cbuffer *C.char
+	cbuffer_len := C.paddle_optimizer_get_state(o.opt, &cbuffer)
+	return cArrayToSlice(unsafe.Pointer(cbuffer), int(cbuffer_len))
+}
+
 func (o *optimizer) UpdateParameter(g Gradient) error {
 	if o.elementType != g.ElementType {
 		return fmt.Errorf("Name: %s, parameter and gradient element type not match, parameter: %v, gradient: %v", g.Name, o.elementType, g.ElementType)
diff --git a/go/pserver/optimizer_test.go b/go/pserver/optimizer_test.go
index 0b2f4cfa41a630645c128ac13826de9d8b1d521b..d19e9de92e0b33b1d9619adb615a24884097a38f 100644
--- a/go/pserver/optimizer_test.go
+++ b/go/pserver/optimizer_test.go
@@ -19,6 +19,6 @@ func TestOptimizerCreateRelease(t *testing.T) {
 		Param:  p,
 		Config: config,
 	}
-	o := newOptimizer(param)
+	o := newOptimizer(param, nil)
 	o.Cleanup()
 }
diff --git a/go/pserver/service.go b/go/pserver/service.go
index ad16a5708d10bdcb5189a1e1e8abf13c54a72265..6b52d0d896f8bc04fab6c9b68911523cbb7ac8b9 100644
--- a/go/pserver/service.go
+++ b/go/pserver/service.go
@@ -1,9 +1,21 @@
 package pserver
 
 import (
+	"bufio"
+	"bytes"
+	"crypto/md5"
+	"encoding/gob"
+	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
 	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
 )
 
 // ElementType is the type of elements of a Parameter.
@@ -39,26 +51,55 @@ type ParameterWithConfig struct {
 	Config []byte // parameter configuration in Proto Buffer format
 }
 
+// ParameterCheckpoint is Parameter and State checkpoint
+type ParameterCheckpoint struct {
+	ParamConfig ParameterWithConfig
+	State       []byte
+}
+
+// checkpoint signature
+type checkpointMeta struct {
+	UUID      string `json:"uuid"`
+	Md5sum    string `json:"md5sum"`
+	Timestamp string `json:"timestamp"`
+}
+
+// Checkpoint is the pserver shard persist in file
+type Checkpoint []ParameterCheckpoint
+
 // Gradient is the gradient of the parameter.
 type Gradient Parameter
 
 // Service is the RPC service for pserver.
 type Service struct {
-	initialized chan struct{}
-	idx         int
-
-	mu     sync.Mutex
-	optMap map[string]*optimizer
+	initialized        chan struct{}
+	idx                int
+	checkpointInterval time.Duration
+	checkpointPath     string
+	client             *EtcdClient
+	mu                 sync.Mutex
+	optMap             map[string]*optimizer
 }
 
 // NewService creates a new service, will bypass etcd registration if no
 // endpoints specified.
-func NewService(idx int) (*Service, error) {
+func NewService(idx int, seconds int, path string, client *EtcdClient, cp Checkpoint) (*Service, error) {
 	s := &Service{
-		idx: idx,
+		idx:                idx,
+		checkpointInterval: time.Second * time.Duration(seconds),
+		checkpointPath:     path,
+		client:             client,
 	}
 	s.optMap = make(map[string]*optimizer)
 	s.initialized = make(chan struct{})
+
+	if cp != nil {
+		for _, item := range cp {
+			p := item.ParamConfig
+			st := item.State
+			s.optMap[p.Param.Name] = newOptimizer(p, st)
+		}
+	}
 	return s, nil
 }
 
@@ -78,7 +119,7 @@ func (s *Service) InitParam(paramWithConfigs ParameterWithConfig, dummy *int) er
 	// TODO(helin): check if paramWithConfigs.Param.Content is
 	// properly memory aligned, if not, make copy to a memory
 	// aligned region.
-	s.optMap[paramWithConfigs.Param.Name] = newOptimizer(paramWithConfigs)
+	s.optMap[paramWithConfigs.Param.Name] = newOptimizer(paramWithConfigs, nil)
 	return nil
 }
 
@@ -139,10 +180,57 @@ func (s *Service) GetParam(name string, parameter *Parameter) error {
 	return nil
 }
 
-// Save tells the parameter server to save parameters.
-func (s *Service) Save(path string, dummy *int) error {
+// pserver save checkpoint
+func (s *Service) doCheckpoint() error {
 	<-s.initialized
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	cp := make([]ParameterCheckpoint, 0, len(s.optMap))
+	index := 0
+	for name, opt := range s.optMap {
+		var pc ParameterCheckpoint
+		pc.ParamConfig.Param.Name = name
+		pc.ParamConfig.Param.ElementType = opt.elementType
+		pc.ParamConfig.Param.Content = opt.GetWeights()
+		pc.State = opt.GetStates()
+		cp[index] = pc
+		index++
+	}
+	var buf bytes.Buffer
+	encoder := gob.NewEncoder(&buf)
+	err := encoder.Encode(cp)
+	if err != nil {
+		return err
+	}
+
+	cpMeta := checkpointMeta{}
+	cpMeta.UUID = s.checkpointPath + strconv.Itoa(s.idx)
+	cpMeta.Timestamp = time.Now().String()
+	h := md5.New()
+	cpMeta.Md5sum = hex.EncodeToString(h.Sum(buf.Bytes()))
 
-	// TODO
+	cpMetajson, _ := json.Marshal(cpMeta)
+	err = s.client.PutKey(filepath.Join(PsCheckpoint, strconv.Itoa(s.idx)), cpMetajson, 3)
+	if err != nil {
+		return err
+	}
+	if _, err = os.Stat(cpMeta.UUID); os.IsNotExist(err) {
+		log.Info("checkpoint does not exists.")
+	} else {
+		err = os.Remove(cpMeta.UUID)
+		log.Infof("checkpoint %s already exsits, removing ", cpMeta.UUID)
+	}
+	f, err := os.Create(cpMeta.UUID)
+	defer f.Close()
+	if err != nil {
+		return err
+	}
+	writer := bufio.NewWriter(f)
+	_, err = writer.Write(buf.Bytes())
+	writer.Flush()
+	if err != nil {
+		return err
+	}
 	return nil
 }
diff --git a/go/pserver/service_test.go b/go/pserver/service_test.go
index b6d20d2c8b7ba0ccd7ab46669a597a21dc11c381..9bf1a48a596f3e3e73a2e4df651855fd5f4e775f 100644
--- a/go/pserver/service_test.go
+++ b/go/pserver/service_test.go
@@ -15,7 +15,8 @@ const (
 )
 
 func TestServiceFull(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -86,7 +87,8 @@ func TestServiceFull(t *testing.T) {
 }
 
 func TestMultipleInit(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -102,7 +104,8 @@ func TestMultipleInit(t *testing.T) {
 }
 
 func TestUninitialized(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	err = s.SendGrad(pserver.Gradient{}, nil)
 	if err.Error() != pserver.Uninitialized {
 		t.FailNow()
@@ -110,7 +113,8 @@ func TestUninitialized(t *testing.T) {
 }
 
 func TestBlockUntilInitialized(t *testing.T) {
-	s, err := pserver.NewService(0)
+	var cp pserver.Checkpoint
+	s, err := pserver.NewService(0, 1, "", nil, cp)
 	if err != nil {
 		t.Error(err)
 	}
@@ -128,16 +132,6 @@ func TestBlockUntilInitialized(t *testing.T) {
 		ch <- struct{}{}
 	}()
 
-	wg.Add(1)
-	go func() {
-		err := s.Save("", nil)
-		if err != nil {
-			errCh <- err
-		}
-		wg.Done()
-		ch <- struct{}{}
-	}()
-
 	time.Sleep(50 * time.Millisecond)
 
 	select {
@@ -170,3 +164,7 @@ func TestBlockUntilInitialized(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestCheckpointSpeed(t *testing.T) {
+	//TODO(zhihong): test speed
+}
diff --git a/paddle/framework/CMakeLists.txt b/paddle/framework/CMakeLists.txt
index 4409c6feae218222b7c0216760cebe4ae8e235cb..e6e3b79d7bd1129e102fde780c8e609a16745e75 100644
--- a/paddle/framework/CMakeLists.txt
+++ b/paddle/framework/CMakeLists.txt
@@ -16,3 +16,6 @@ py_proto_compile(framework_py_proto SRCS attr_type.proto op_proto.proto op_desc.
 # Generate an empty __init__.py to make framework_py_proto as a valid python module.
 add_custom_target(framework_py_proto_init ALL COMMAND ${CMAKE_COMMAND} -E touch __init__.py)
 add_dependencies(framework_py_proto framework_py_proto_init)
+
+proto_library(net_proto SRCS net_proto.proto DEPS op_proto)
+cc_library(net SRCS net.cc DEPS net_proto attr_type op_proto)
diff --git a/paddle/framework/net.cc b/paddle/framework/net.cc
new file mode 100644
index 0000000000000000000000000000000000000000..73b3051235ee90b31bd65acb22f454fc13d64da9
--- /dev/null
+++ b/paddle/framework/net.cc
@@ -0,0 +1,20 @@
+#include "paddle/framework/net.h"
+
+namespace paddle {
+namespace framework {
+
+PlainNet::PlainNet(const NetDesc& def) {}
+
+void PlainNet::InferShape(Scope* scope) {
+  for (auto& op : ops_) {
+    op.InferShape();
+  }
+}
+
+void PlainNet::Run(std::shared_ptr<Scope> scope, DeviceContext* ctx) {
+  for (auto& op : ops_) {
+    op.Run(ctx);
+  }
+}
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/net.h b/paddle/framework/net.h
new file mode 100644
index 0000000000000000000000000000000000000000..76992e07282904fd1074bb0ced2367a8d20e3ec2
--- /dev/null
+++ b/paddle/framework/net.h
@@ -0,0 +1,171 @@
+/* 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 "paddle/framework/net_proto.pb.h"
+#include "paddle/framework/op_proto.pb.h"
+#include "paddle/framework/scope.h"
+#include "paddle/platform/device_context.h"
+
+namespace paddle {
+namespace framework {
+using namespace paddle::platform;
+
+// operator's index stored in a network.
+typedef int OpIndex;
+/**
+ * NOTE following codes are some definitions of unimplemented concepts.
+ * We write some basic implementation to make Net compilable. These APIs will
+ * keep updating if the concepts related are implemented.
+ */
+
+struct OpDesc;
+struct OpAttrs {};
+
+class Operator {
+ public:
+  Operator(const OpDesc &def) {}
+  void InferShape() {}
+  void Run(DeviceContext *ctx) {}
+};
+
+/**
+ * @brief Network that manage the operators it has.
+ *
+ * Network is the container and controller of a set of operators, user can build
+ * a real network from a NetDesc which is a protobuf message and use
+ * Network.Run() * to run all the operators in the network.
+
+ * A network object knows all Operators belonging to this network. Variables,
+ * which are inputs and outputs of these operators, are created and managed by a
+ * hierarchy of Scope objects.
+ *
+ * This is the base class of network, all the networks should implement the apis
+ * it defines.
+ */
+class Net {
+ public:
+  /**
+   * @brief Infer shapes of all inputs and outputs of operators.
+   */
+  virtual void InferShape(Scope *scope) = 0;
+  /**
+   * @brief Run the network.
+   *
+   * Run all the operators and return success(true) or not, with all the
+   * variables are located in `scope`. `context` describes the detail execution
+   * environment for ops. `begin` and `end` specify the scope of `ops_` to run,
+   * If no positive indexes are provided, all operators in `ops_` will run.
+   */
+  virtual void Run(std::shared_ptr<Scope> scope, DeviceContext *ctx) = 0;
+
+  /**
+   * @brief Add an Operator according to `def`.
+   */
+  virtual OpIndex AddOp(const OpProto &def) = 0;
+
+  /**
+   * @brief Add optimizer operators acctording to `attrs`.
+   */
+  virtual void AddOptimizerOps(const OpAttrs &attrs) = 0;
+
+  /**
+   * @brief Add backward operators.
+   */
+  virtual void AddBackwardOps() = 0;
+
+  /**
+   * @brief Create a network.
+   */
+  static std::unique_ptr<Net> Create(const NetDesc &def = NetDesc());
+
+  virtual ~Net() {}
+};
+
+/**
+ * @brief a basic implementation of Net.
+ *
+ * PlainNet is a very simple Net, it create a list of operators, and run them
+ * sequentially following the order they added.
+ */
+class PlainNet : public Net {
+ public:
+  /**
+   * @brief Initialize a PlainNet.
+   *
+   * Initialize from  a network describe by `def`. NetDesc is the definition of
+   * a network.
+   */
+  PlainNet(const NetDesc &def);
+
+  /**
+   * Infer all the operators' input and output varialbes' shapes, will be called
+   * before every mini-batch
+   */
+  virtual void InferShape(Scope *scope) override;
+
+  /**
+   * @brief Run the network.
+   *
+   * Run all the operators with the `scope`, if no scope is provided, default
+   * scope will be used instead. If no OpContext is provicded, default context
+   * will be used.
+   */
+  virtual void Run(std::shared_ptr<Scope> scope, DeviceContext *ctx) override;
+
+  /**
+   * @brief Add an operator to this network.
+   */
+  virtual OpIndex AddOp(const OpProto &def) override;
+
+  /**
+   * @brief Add all optimizer operators related into the network.
+   */
+  virtual void AddOptimizerOps(const OpAttrs &attrs) override;
+
+  /**
+   * @brief Add all backward operators related into the network.
+   */
+  virtual void AddBackwardOps() override;
+
+  virtual ~PlainNet() override {}
+
+ protected:
+  /**
+   * @brief Build the network.
+   *
+   * Create operators accordding to `def`, will be called by the constructor.
+   */
+  void BuildNet(const NetDesc &def);
+
+  /**
+   * @brief Add an operator into this network.
+   *
+   * Add a operator which is identified as `type` and has attributes described
+   * in `attrs`, the `inputs` are the keys of readonly input variables,
+   * `outputs` are keys of mutable output variables. An `OpIndex` will be
+   * returned to indicate the offset of the new operator in `ops_`.
+   */
+  OpIndex AddOp(const std::string &type, const std::vector<std::string> &inputs,
+                const std::vector<std::string> &outputs,
+                const OpAttrs &attrs = OpAttrs());
+
+ private:
+  // the operators owned by `Network`.
+  std::vector<Operator> ops_;
+};
+
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/net_proto.proto b/paddle/framework/net_proto.proto
new file mode 100644
index 0000000000000000000000000000000000000000..0779f49fe2a9a6d0d1ea5ec11ba3befeb0a67fa1
--- /dev/null
+++ b/paddle/framework/net_proto.proto
@@ -0,0 +1,15 @@
+syntax="proto2";
+package paddle.framework;
+
+import "op_proto.proto";
+
+message NetDesc {
+  // network identification
+  optional string name = 1;
+  // operator contains in network
+  repeated OpProto operators = 2;
+  // network type to run with. e.g "plainNet", "DAG"
+  optional string net_type = 3;
+  // num worker always
+  optional int32 num_workers = 4;
+}
diff --git a/paddle/framework/net_test.cc b/paddle/framework/net_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a8e31c1497519ce60da004bc0a3e52403593497c
--- /dev/null
+++ b/paddle/framework/net_test.cc
@@ -0,0 +1,24 @@
+/* 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/framework/net.h"
+#include "paddle/framework/op_registry.h"
+
+#include <gtest/gtest.h>
+
+namespace paddle {
+namespace framework {
+class FakeFC : public Operator {}
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/op_registry_test.cc b/paddle/framework/op_registry_test.cc
index 17849ca0191db644884e766342b30461abf50298..ae6b7387129c6f82d0c63270d5368da65abd3b51 100644
--- a/paddle/framework/op_registry_test.cc
+++ b/paddle/framework/op_registry_test.cc
@@ -119,4 +119,4 @@ TEST(OpRegistry, CustomChecker) {
   for (size_t i = 0; i < debug_str.length(); ++i) {
     ASSERT_EQ(debug_str[i], str[i]);
   }
-}
\ No newline at end of file
+}
diff --git a/paddle/memory/detail/buddy_allocator.cc b/paddle/memory/detail/buddy_allocator.cc
index 2cfacec46c108f3a25c82469059981ca0f721ed6..3f630973e906ca56a62994c7aba92937b40887b7 100644
--- a/paddle/memory/detail/buddy_allocator.cc
+++ b/paddle/memory/detail/buddy_allocator.cc
@@ -151,7 +151,13 @@ void BuddyAllocator::Free(void* p) {
   pool_.insert(
       IndexSizeAddress(block->index(cache_), block->total_size(cache_), block));
 
-  // TODO(gangliao): Clean up if existing too much free memory
+  // Clean up if existing too much free memory
+  
+  // Prefer freeing fallback allocation first
+  CleanIdleFallBackAlloc();
+
+  // Free normal allocation
+  CleanIdleNormalAlloc();
 }
 
 size_t BuddyAllocator::Used() { return total_used_; }
@@ -249,6 +255,11 @@ void* BuddyAllocator::SplitToAlloc(BuddyAllocator::PoolSet::iterator it,
   return block;
 }
 
+void BuddyAllocator::CleanIdleFallBackAlloc() {
+  
+}
+
+
 }  // namespace detail
 }  // namespace memory
 }  // namespace paddle
diff --git a/paddle/memory/detail/buddy_allocator.h b/paddle/memory/detail/buddy_allocator.h
index a89dd8eb7c19dea61805e78592ac949f2641e908..14ee1fa07c031da5f2c40bb926f5931158a5d102 100644
--- a/paddle/memory/detail/buddy_allocator.h
+++ b/paddle/memory/detail/buddy_allocator.h
@@ -43,10 +43,11 @@ class BuddyAllocator {
   size_t Used();
 
  public:
-  // Disable copy and assignment.
+  // Disable copy and assignment
   BuddyAllocator(const BuddyAllocator&) = delete;
   BuddyAllocator& operator=(const BuddyAllocator&) = delete;
 
+ private:
   // Tuple (allocator index, memory size, memory address)
   using IndexSizeAddress = std::tuple<size_t, size_t, void*>;
   // Each element in PoolSet is a free allocation
@@ -59,16 +60,25 @@ class BuddyAllocator {
   PoolSet::iterator RefillPool();
 
   /**
-   *  \brief Find the suitable chunk from existing pool
+   *  \brief   Find the suitable chunk from existing pool and split
+   *           it to left and right buddies
+   *
+   *  \param   it     the iterator of pool list
+   *  \param   size   the size of allocation
    *
-   *  \param it   pool iterator which contains suitable block.
-   *  \param size the size of allocation.
+   *  \return  the left buddy address
    */
   void* SplitToAlloc(PoolSet::iterator it, size_t size);
 
-  /*! \brief Find the existing chunk which used to allocation  */
+  /*! \brief Find the existing chunk which used to allocation */
   PoolSet::iterator FindExistChunk(size_t size);
 
+  /*! \brief Clean idle fallback allocation */
+  void CleanIdleFallBackAlloc();
+
+  /*! \brief Clean idle normal allocation */
+  void CleanIdleNormalAlloc();
+
  private:
   size_t total_used_ = 0;  // the total size of used memory
   size_t total_free_ = 0;  // the total size of free memory
diff --git a/paddle/memory/memory_test.cc b/paddle/memory/memory_test.cc
index a98ccbb806830176815d8198e2eb324f26bde860..fed7444798fe22478138803c1e8a8322993031c3 100644
--- a/paddle/memory/memory_test.cc
+++ b/paddle/memory/memory_test.cc
@@ -30,6 +30,21 @@ TEST(BuddyAllocator, CPUAllocation) {
   paddle::memory::Free(cpu, p);
 }
 
+TEST(BuddyAllocator, CPUMultAlloc) {
+  paddle::platform::CPUPlace cpu;
+
+  std::vector<void*> ps;
+  ps.reserve(8);
+
+  for (auto size : {256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304}) {
+    ps.emplace_back(paddle::memory::Alloc(cpu, size));
+  }
+
+  for (auto p : ps) {
+    paddle::memory::Free(cpu, p);
+  }
+}
+
 #ifndef PADDLE_ONLY_CPU
 
 TEST(BuddyAllocator, GPUAllocation) {
diff --git a/paddle/platform/CMakeLists.txt b/paddle/platform/CMakeLists.txt
index bf3e8f31abe44dff2236336f815a44a46133f570..4b3f55b3c77244a865b328f22861a69697f7727a 100644
--- a/paddle/platform/CMakeLists.txt
+++ b/paddle/platform/CMakeLists.txt
@@ -7,3 +7,5 @@ cc_library(place SRCS place.cc)
 cc_test(place_test SRCS place_test.cc DEPS place glog gflags)
 
 cc_library(dynamic_loader SRCS dynload/dynamic_loader.cc DEPS gflags glog)
+
+nv_test(device_context_test SRCS device_context_test.cc DEPS dynamic_loader place eigen3)
diff --git a/paddle/platform/device_context.h b/paddle/platform/device_context.h
new file mode 100644
index 0000000000000000000000000000000000000000..160eb4e12060b36c4fefba499d4e83b9aab92848
--- /dev/null
+++ b/paddle/platform/device_context.h
@@ -0,0 +1,160 @@
+/* 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 "paddle/framework/enforce.h"
+#ifndef PADDLE_ONLY_CPU
+#include "paddle/platform/cuda.h"
+#include "paddle/platform/dynload/cublas.h"
+#include "paddle/platform/dynload/cudnn.h"
+#include "paddle/platform/dynload/curand.h"
+#define EIGEN_USE_GPU
+#endif
+#include "paddle/platform/place.h"
+#include "unsupported/Eigen/CXX11/Tensor"
+
+namespace paddle {
+namespace platform {
+
+class DeviceContext {
+ public:
+  virtual ~DeviceContext() {}
+};
+
+class CPUDeviceContext : public DeviceContext {};
+
+#ifndef PADDLE_ONLY_CPU
+
+class GPUPlaceGuard {
+ public:
+  explicit GPUPlaceGuard(GPUPlace new_place) : previous_(GetCurrentDeviceId()) {
+    if (previous_ != new_place) {
+      paddle::platform::SetDeviceId(new_place.device);
+    }
+  }
+
+  ~GPUPlaceGuard() { paddle::platform::SetDeviceId(previous_.device); }
+
+ private:
+  GPUPlace previous_;
+};
+
+class CUDADeviceContext : public DeviceContext {
+ public:
+  explicit CUDADeviceContext(const GPUPlace gpu_place) : gpu_place_(gpu_place) {
+    GPUPlaceGuard guard(gpu_place_);
+    paddle::platform::throw_on_error(cudaStreamCreate(&stream_),
+                                     "cudaStreamCreate failed");
+    eigen_stream_ = new Eigen::CudaStreamDevice(&stream_);
+    eigen_device_ = new Eigen::GpuDevice(eigen_stream_);
+  }
+
+  void Wait() {
+    paddle::platform::throw_on_error(cudaStreamSynchronize(stream_),
+                                     "cudaStreamSynchronize failed");
+  }
+
+  cudaStream_t stream() { return stream_; }
+
+  Eigen::GpuDevice eigen_device() { return *eigen_device_; }
+
+  cublasHandle_t cublas_handle() {
+    if (!blas_handle_) {
+      GPUPlaceGuard guard(gpu_place_);
+      PADDLE_ENFORCE(paddle::platform::dynload::cublasCreate(&blas_handle_) ==
+                         CUBLAS_STATUS_SUCCESS,
+                     "cublasCreate failed");
+      PADDLE_ENFORCE(paddle::platform::dynload::cublasSetStream(
+                         blas_handle_, stream_) == CUBLAS_STATUS_SUCCESS,
+                     "cublasSetStream failed");
+    }
+    return blas_handle_;
+  }
+
+  cudnnHandle_t cudnn_handle() {
+    if (!dnn_handle_) {
+      GPUPlaceGuard guard(gpu_place_);
+      PADDLE_ENFORCE(paddle::platform::dynload::cudnnCreate(&dnn_handle_) ==
+                         CUDNN_STATUS_SUCCESS,
+                     "cudnnCreate failed");
+      PADDLE_ENFORCE(paddle::platform::dynload::cudnnSetStream(
+                         dnn_handle_, stream_) == CUDNN_STATUS_SUCCESS,
+                     "cudnnSetStream failed");
+    }
+    return dnn_handle_;
+  }
+
+  curandGenerator_t curand_generator() {
+    if (!rand_generator_) {
+      GPUPlaceGuard guard(gpu_place_);
+      PADDLE_ENFORCE(paddle::platform::dynload::curandCreateGenerator(
+                         &rand_generator_, CURAND_RNG_PSEUDO_DEFAULT) ==
+                         CURAND_STATUS_SUCCESS,
+                     "curandCreateGenerator failed");
+      PADDLE_ENFORCE(
+          paddle::platform::dynload::curandSetPseudoRandomGeneratorSeed(
+              rand_generator_, random_seed_) == CURAND_STATUS_SUCCESS,
+          "curandSetPseudoRandomGeneratorSeed failed");
+      PADDLE_ENFORCE(paddle::platform::dynload::curandSetStream(
+                         rand_generator_, stream_) == CURAND_STATUS_SUCCESS,
+                     "curandSetStream failed");
+    }
+    return rand_generator_;
+  }
+
+  ~CUDADeviceContext() {
+    Wait();
+    if (blas_handle_) {
+      PADDLE_ENFORCE(paddle::platform::dynload::cublasDestroy(blas_handle_) ==
+                         CUBLAS_STATUS_SUCCESS,
+                     "cublasDestroy failed");
+    }
+
+    if (dnn_handle_) {
+      PADDLE_ENFORCE(paddle::platform::dynload::cudnnDestroy(dnn_handle_) ==
+                         CUDNN_STATUS_SUCCESS,
+                     "cudnnDestroy failed");
+    }
+
+    if (rand_generator_) {
+      PADDLE_ENFORCE(paddle::platform::dynload::curandDestroyGenerator(
+                         rand_generator_) == CURAND_STATUS_SUCCESS,
+                     "curandDestroyGenerator failed");
+    }
+
+    delete eigen_stream_;
+    delete eigen_device_;
+
+    paddle::platform::throw_on_error(cudaStreamDestroy(stream_),
+                                     "cudaStreamDestroy failed");
+  }
+
+ private:
+  GPUPlace gpu_place_;
+  cudaStream_t stream_;
+
+  Eigen::CudaStreamDevice* eigen_stream_;
+  Eigen::GpuDevice* eigen_device_;
+
+  cublasHandle_t blas_handle_{nullptr};
+
+  cudnnHandle_t dnn_handle_{nullptr};
+
+  int random_seed_;
+  curandGenerator_t rand_generator_{nullptr};
+};
+#endif
+}  // namespace platform
+}  // namespace paddle
diff --git a/paddle/platform/device_context_test.cc b/paddle/platform/device_context_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..61be4a307dbf073be7dff4564183240834cc7df6
--- /dev/null
+++ b/paddle/platform/device_context_test.cc
@@ -0,0 +1,33 @@
+/* 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/device_context.h"
+#include "gtest/gtest.h"
+
+TEST(CUDADeviceContext, Init) {
+  int count = paddle::platform::GetDeviceCount();
+  for (int i = 0; i < count; i++) {
+    paddle::platform::CUDADeviceContext* device_context =
+        new paddle::platform::CUDADeviceContext(i);
+    Eigen::GpuDevice gpu_device = device_context->eigen_device();
+    ASSERT_NE(nullptr, gpu_device.stream());
+    cudnnHandle_t cudnn_handle = device_context->cudnn_handle();
+    ASSERT_NE(nullptr, cudnn_handle);
+    cublasHandle_t cublas_handle = device_context->cublas_handle();
+    ASSERT_NE(nullptr, cublas_handle);
+    curandGenerator_t curand_handle = device_context->curand_generator();
+    ASSERT_NE(nullptr, curand_handle);
+    delete device_context;
+  }
+}
diff --git a/python/paddle/trainer_config_helpers/networks.py b/python/paddle/trainer_config_helpers/networks.py
index b77932ce5f09470329a97cc0a6273942a9155c6a..f0b6625dc3736852980c889232d17853290863ac 100755
--- a/python/paddle/trainer_config_helpers/networks.py
+++ b/python/paddle/trainer_config_helpers/networks.py
@@ -1395,7 +1395,7 @@ def inputs(layers, *args):
     if len(args) != 0:
         layers.extend(args)
 
-    Inputs(* [l.name for l in layers])
+    Inputs(*[l.name for l in layers])
 
 
 def outputs(layers, *args):
@@ -1438,7 +1438,7 @@ def outputs(layers, *args):
     assert len(layers) > 0
 
     if HasInputsSet():  # input already set
-        Outputs(* [l.name for l in layers])
+        Outputs(*[l.name for l in layers])
         return  # just return outputs.
 
     if len(layers) != 1:
diff --git a/python/paddle/v2/dataset/wmt14.py b/python/paddle/v2/dataset/wmt14.py
index e1dc4f4c30051202e8fd077087679c4fd6cbd7a0..2a631c365f27a6039021a56268a62017638c2739 100644
--- a/python/paddle/v2/dataset/wmt14.py
+++ b/python/paddle/v2/dataset/wmt14.py
@@ -32,9 +32,9 @@ MD5_DEV_TEST = '7d7897317ddd8ba0ae5c5fa7248d3ff5'
 # this is a small set of data for test. The original data is too large and will be add later.
 URL_TRAIN = 'http://paddlepaddle.cdn.bcebos.com/demo/wmt_shrinked_data/wmt14.tgz'
 MD5_TRAIN = '0791583d57d5beb693b9414c5b36798c'
-# this is the pretrained model, whose bleu = 26.92
+# BLEU of this trained model is 26.92
 URL_MODEL = 'http://paddlepaddle.bj.bcebos.com/demo/wmt_14/wmt14_model.tar.gz'
-MD5_MODEL = '4ce14a26607fb8a1cc23bcdedb1895e4'
+MD5_MODEL = '0cb4a5366189b6acba876491c8724fa3'
 
 START = "<s>"
 END = "<e>"