diff --git a/cmake/external/nccl.cmake b/cmake/external/nccl.cmake
index 10e8e838095d5f4ddd4161d26a188ab8166d10fa..dfbbed58c9ed7cc57809b3d33a29ce26a35d75a2 100644
--- a/cmake/external/nccl.cmake
+++ b/cmake/external/nccl.cmake
@@ -2,7 +2,7 @@ INCLUDE(ExternalProject)
 
 SET(NCCL_SOURCE_DIR ${THIRD_PARTY_PATH}/nccl)
 
-INCLUDE_DIRECTORIES(${NCCL_SOURCE_DIR}/src/extern_nccl)
+INCLUDE_DIRECTORIES(${NCCL_SOURCE_DIR}/src/extern_nccl/src)
 
 
 if(WITH_DSO)
diff --git a/paddle/operators/math/im2col.h b/paddle/operators/math/im2col.h
index c736d4fa523c2af3e3dd7a11114d7f84021bc5c1..a1cb956c51ebfa80892745b88a6d85a0f09202d6 100644
--- a/paddle/operators/math/im2col.h
+++ b/paddle/operators/math/im2col.h
@@ -75,7 +75,8 @@ class Im2ColFunctor {
   void operator()(const platform::DeviceContext& context,
                   const framework::Tensor& im, framework::Tensor& col,
                   int stride_height, int stride_width, int padding_up,
-                  int padding_down, int padding_left, int padding_right);
+                  int padding_down, int padding_left = 0,
+                  int padding_right = 0);
 };
 
 template <ColFormat Format, typename Place, typename T>
@@ -84,7 +85,7 @@ class Col2ImFunctor {
   void operator()(const platform::DeviceContext& context, framework::Tensor& im,
                   const framework::Tensor& col, int stride_height,
                   int stride_width, int padding_up, int padding_down,
-                  int padding_left, int padding_right);
+                  int padding_left = 0, int padding_right = 0);
 };
 
 }  // namespace math
diff --git a/python/paddle/v2/parameters.py b/python/paddle/v2/parameters.py
index d0b5ff12f2748909745294d4ba96888f2baf2b8d..bd97dc1199fedc8ac91c1c6086957e8cce88bdc4 100644
--- a/python/paddle/v2/parameters.py
+++ b/python/paddle/v2/parameters.py
@@ -326,6 +326,17 @@ class Parameters(object):
         self.set(name, arr.reshape(self.get_shape(name)))
 
     def to_tar(self, f):
+        """
+        Save parameters to a tar file.
+
+        WARNING: You should use `paddle.v2.trainer.SGD.save_parameter_to_tar(f)`
+            to save parameters most of the time. Otherwise, some settings such
+            as model average will not take effect.
+
+        :param f:
+        :type f: file
+        :return:
+        """
         tar = tarfile.TarFile(fileobj=f, mode='w')
         for nm in self.names():
             buf = cStringIO.StringIO()