modify code comments.

paddle/cuda/include/hl_batch_norm.h

@@ -27,9 +27,7 @@ limitations under the License. */
  * @param[in]   bias          batch normalization bias parameter (in original
  *                            paper scale is referred to as beta).
  * @param[in]   estimatedMean
- * @param[in]   estimatedVar It is suggested that resultRunningMean,
- *                           resultRunningVariance from the
- *                           cudnnBatchNormalizationForwardTraining call
+ * @param[in]   estimatedVar  The moving mean and variance
  *                            accumulated during the training phase are passed
  *                            as inputs here.
  * @param[in]   epsilon       Epsilon value used in the batch

paddle/gserver/layers/CudnnBatchNormLayer.cpp

@@ -81,8 +81,8 @@ void CudnnBatchNormLayer::forward(PassType passType) {
   } else {
     // used movingMean and movingVar in testing
     if (batchSize > 1024) {
-      // when batchSize is larger than 1024, there is a bug
-      // in cudnn library.
+      // there is a bug in cudnn library when the batch size
+      // is larger than 1024.
       hl_batch_norm_cuda_inference(input,
                                    output,
                                    gamma,