Switched to non-bucketed comm

examples/imagenet/main.py

@@ -131,7 +131,8 @@ def main():
     if args.fp16:
         model = network_to_half(model)
     if args.distributed:
-        model = DDP(model)
+        #shared param turns off bucketing in DDP, for lower latency runs this can improve perf
+        model = DDP(model, shared_param=True)
 
     global model_params, master_params
     if args.fp16: