[Model Loading] Overlap checkpoint staging with CUDA graph capture during startup (#32017)

Co-authored-by: Wenhui Zhu <wzhu59@asu.edu>
Co-authored-by: Alex Nails <alex.nails@radixark.ai>

python/sglang/benchmark/one_batch.py

@@ -350,9 +350,13 @@ def load_model(server_args, port_args, gpu_id, tp_rank):
         model_runner = MlxModelRunnerStub(**runner_kwargs)
     else:
         model_runner = ModelRunner(**runner_kwargs)
+        if server_args.is_startup_weight_load_overlap:
+            model_runner.start_startup_weight_load()
         model_runner.alloc_memory_pool()
         model_runner.init_attention_backends()
         model_runner.init_cuda_graphs()
+        if server_args.is_startup_weight_load_overlap:
+            model_runner.finalize_startup_weight_load()
     rank_print(f"max_total_num_tokens={model_runner.max_total_num_tokens}")
     tokenizer = get_tokenizer(
         server_args.tokenizer_path,