test=develop, accelerate_hs_op and add prefetch with is_sparse

paddle/fluid/operators/hierarchical_sigmoid_op.h

@@ -40,8 +40,9 @@ using platform::Transform;
 
 static std::vector<int64_t> PathToRows(const framework::LoDTensor& path) {
   std::set<int64_t> rows;
+  const int64_t* paths = path.data<int64_t>();
   for (int64_t i = 0; i < path.numel(); ++i) {
-    int64_t row = path.data<int64_t>()[i];
+    int64_t row = paths[i];
     if (row < 0) {
       continue;
     }

python/paddle/fluid/layers/nn.py

@@ -5013,9 +5013,10 @@ def nce(input,
     else:
         num_neg_samples = int(num_neg_samples)
 
-    remote_prefetch = False
-    if os.environ.get('PADDLE_ENABLE_REMOTE_PREFETCH'):
-        remote_prefetch = True
+    remote_prefetch = is_sparse
+    print(
+        "With sparse mode, if your models has only small parameter prefetch may cause speed down"
+    )
 
     attrs = {
         'num_total_classes': int(num_total_classes),
@@ -5133,10 +5134,10 @@ def hsigmoid(input,
         pass
 
     weights = None
-    remote_prefetch = False
-    if os.environ.get('PADDLE_ENABLE_REMOTE_PREFETCH'):
-        remote_prefetch = True
-
+    remote_prefetch = is_sparse
+    print(
+        "With sparse mode, if your models has only small parameter prefetch may cause speed down"
+    )
     if not is_custom:
         weights = helper.create_parameter(
             attr=helper.param_attr,