[v1] torchrun compatibility (#13642)

Signed-off-by: youkaichao <youkaichao@gmail.com>

tests/distributed/test_torchrun_example.py

@@ -48,6 +48,12 @@ test_consistent_across_ranks(
 test_consistent_across_ranks(
     llm.llm_engine.vllm_config.cache_config.num_gpu_blocks)
 
+# make sure we can access the model parameters from the calling process
+# of the `LLM` instance.
+params = list(llm.llm_engine.model_executor.driver_worker.worker.model_runner.
+              model.parameters())
+test_consistent_across_ranks(len(params))
+
 # all ranks should have the same outputs
 for output in outputs:
     prompt = output.prompt