minor refine

Author: wooyeonlee0

vllm/config.py

@@ -941,14 +941,17 @@ def _maybe_override_draft_max_model_len(
     @staticmethod
     def create_draft_parallel_config(
             target_parallel_config: ParallelConfig,
-            speculative_tensor_parallel_size: int) -> ParallelConfig:
+            speculative_tensor_parallel_size: Optional[int]) -> ParallelConfig:
         """Create a parallel config for use by the draft worker.
 
         This is mostly a copy of the target parallel config.
         """
+
+        _speculative_tensor_parallel_size = speculative_tensor_parallel_size or target_parallel_config.tensor_parallel_size
+
         draft_parallel_config = ParallelConfig(
             pipeline_parallel_size=target_parallel_config.pipeline_parallel_size,
-            tensor_parallel_size=target_parallel_config.tensor_parallel_size,
+            tensor_parallel_size=_speculative_tensor_parallel_size,
             distributed_executor_backend=target_parallel_config.
             distributed_executor_backend,
             max_parallel_loading_workers=target_parallel_config.
@@ -961,9 +964,6 @@ def create_draft_parallel_config(
             placement_group=target_parallel_config.placement_group,
         )
 
-        if speculative_tensor_parallel_size is not None:
-            draft_parallel_config.tensor_parallel_size = speculative_tensor_parallel_size
-
         return draft_parallel_config
 
     def __init__(