add check

python/paddle_serving_server_gpu/serve.py

@@ -69,7 +69,8 @@ def start_multi_card(args):  # pylint: disable=doc-string-missing
         gpus = args.gpu_ids.split(",")
         if "CUDA_VISIBLE_DEVICES" in os.environ:
             env_gpus = os.environ["CUDA_VISIBLE_DEVICES"].split(",")
-            if int(gpus[-1]) >= len(env_gpus):
+            for ids in gpus:
+                if int(ids) >= len(env_gpus):
                     print(
                         " Max index of gpu_ids out of range, the number of CUDA_VISIBLE_DEVICES is {}.".
                         format(len(env_gpus)))