diff --git a/configs/pascal_voc/ssd300_voc.py b/configs/pascal_voc/ssd300_voc.py
index 79d60e95c740636610d266a681ba4f48d6b2c66b..88f662ca3062c04997dbbf15589f0ba7f886a757 100644
--- a/configs/pascal_voc/ssd300_voc.py
+++ b/configs/pascal_voc/ssd300_voc.py
@@ -1,3 +1,4 @@
+benchmark = True
 # model settings
 input_size = 300
 model = dict(
diff --git a/configs/pascal_voc/ssd512_voc.py b/configs/pascal_voc/ssd512_voc.py
index 25e1369b9e84edb1cea7c77bcce1aa12128baa95..c670cc7bd8df887df0f1a0318226dd394cd88266 100644
--- a/configs/pascal_voc/ssd512_voc.py
+++ b/configs/pascal_voc/ssd512_voc.py
@@ -1,3 +1,4 @@
+benchmark = True
 # model settings
 input_size = 512
 model = dict(
diff --git a/configs/ssd300_coco.py b/configs/ssd300_coco.py
index 781d2df0b927791d16f30753a1cfabd6011e5963..1c14cea56f5f99ae132c9b6f400ab2e82c91693d 100644
--- a/configs/ssd300_coco.py
+++ b/configs/ssd300_coco.py
@@ -1,3 +1,4 @@
+benchmark = True
 # model settings
 input_size = 300
 model = dict(
diff --git a/configs/ssd512_coco.py b/configs/ssd512_coco.py
index 1d9b35299eafc8d06b4c70a4ab27b4fe2a981daf..e410b949aee73512467c1673f1f71a3b295a16a1 100644
--- a/configs/ssd512_coco.py
+++ b/configs/ssd512_coco.py
@@ -1,3 +1,4 @@
+benchmark = True
 # model settings
 input_size = 512
 model = dict(
diff --git a/mmdet/datasets/custom.py b/mmdet/datasets/custom.py
index 1bc842a843b00986ca9cef9d864f098a34d9627f..2ab3be99d07f6517f9370f43994d22d8d374818b 100644
--- a/mmdet/datasets/custom.py
+++ b/mmdet/datasets/custom.py
@@ -47,9 +47,9 @@ class CustomDataset(Dataset):
                  with_mask=True,
                  with_crowd=True,
                  with_label=True,
-                 test_mode=False,
                  extra_aug=None,
-                 resize_keep_ratio=True):
+                 resize_keep_ratio=True,
+                 test_mode=False):
         # prefix of images path
         self.img_prefix = img_prefix
 
diff --git a/tools/train.py b/tools/train.py
index 4ec7e5615430d16c9b6bf0c315dd84df42512c1e..663fdd7a2ce9d9c9846614f68db2fe1a4d09b637 100644
--- a/tools/train.py
+++ b/tools/train.py
@@ -8,6 +8,7 @@ from mmdet.datasets import get_dataset
 from mmdet.apis import (train_detector, init_dist, get_root_logger,
                         set_random_seed)
 from mmdet.models import build_detector
+import torch
 
 
 def parse_args():
@@ -42,6 +43,9 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+    # set benchmark
+    if cfg.get('benchmark', False):
+        torch.backends.cudnn.benchmark = True
     # update configs according to CLI args
     if args.work_dir is not None:
         cfg.work_dir = args.work_dir