### What this PR does / why we need it? In certain scenarios, the performance of synchronously loading data from the pool is better than that of asynchronously loading data. Therefore, a control logic (or switch) for asynchronous loading from the pool has been added. ### Does this PR introduce _any_ user-facing change? ### How was this patch tested? - vLLM version: v0.11.0rc3 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0 --------- <!-- Thanks for sending a pull request! BEFORE SUBMITTING, PLEASE READ https://docs.vllm.ai/en/latest/contributing/overview.html Signed-off-by: fems14 <1804143737@qq.com>