Result is a bit misleading#3

The benchmark result just scared me. I was quite afraid of the overhead of async. For me, even 1 us is an eternality. However, I made my own [benchmark](https://github.com/qiujiangkun/rust-async-bench) As the result suggests, there is about 1.5 ns's performance panelty per `async`/`await`. I think there's a few flaws with your method. - You crafted your own runtime. I choose tokio for benchmarking because it's the most mature async runtime. There are even more crazy crates like `glommio`. - Your way of interaction with IO. There are better approaches, like mio(which tokio is built on), epoll, even dpdk.