fix errors by comment

benchmark/fluid/fluid_benchmark.py

@@ -267,7 +267,7 @@ def train(avg_loss, infer_prog, optimizer, train_reader, test_reader, batch_acc,
             # pass is not the last, the last batch of this pass
             # is also equal to args.batch_size.
             if args.use_reader_op:
-                num_samples += args.batch_size
+                num_samples += args.batch_size * args.gpus
             else:
                 num_samples += len(data)
             train_losses.append(loss)
@@ -363,7 +363,7 @@ def train_parallel(avg_loss, infer_prog, optimizer, train_reader, test_reader,
             if args.update_method == "pserver":
                 exe.bcast_params()
             if args.use_reader_op:
-                num_samples += args.batch_size
+                num_samples += args.batch_size * args.gpus
             else:
                 num_samples += len(data)
             iters += 1