update benchmark_storage with instructions

Summary: Also modify launch() because it should not assume it's always called with a CfgNode object.

Differential Revision: D31494215

fbshipit-source-id: 8f07e9cb64969f8a14641956f7ef7c7160748bd9

d2go/distributed.py

@@ -64,8 +64,7 @@ def launch(
     if get_launch_environment() == "local" and not torch.cuda.is_available():
         assert len(args) > 0, args
         cfg = args[0]
-        assert isinstance(cfg, CfgNode)
-        if cfg.MODEL.DEVICE == "cuda":
+        if isinstance(cfg, CfgNode) and cfg.MODEL.DEVICE == "cuda":
             logger.warning(
                 "Detected that CUDA is not available on this machine, set MODEL.DEVICE"
                 " to cpu and backend to GLOO"