Merge pull request #5176 from willdzeng/mnist_conv_improve

Improved mnist/convolution.py performance

tensorflow/models/image/mnist/convolutional.py

@@ -296,11 +296,13 @@ def main(_):
       # node in the graph it should be fed to.
       feed_dict = {train_data_node: batch_data,
                    train_labels_node: batch_labels}
-      # Run the graph and fetch some of the nodes.
-      _, l, lr, predictions = sess.run(
-          [optimizer, loss, learning_rate, train_prediction],
-          feed_dict=feed_dict)
+      # Run the optimizer to update weights.
+      sess.run(optimizer, feed_dict=feed_dict)
+      # print some extra information once reach the evaluation frequency
       if step % EVAL_FREQUENCY == 0:
+        # fetch some extra nodes' data
+        l, lr, predictions = sess.run([loss, learning_rate, train_prediction],
+                                      feed_dict=feed_dict)
         elapsed_time = time.time() - start_time
         start_time = time.time()
         print('Step %d (epoch %.2f), %.1f ms' %