I'm testing io_uring for file I/O for a database engine, which is a very different code path than networking with epoll, and so far I've been disappointed to fi

I'm testing io_uring for file I/O for a database engine, which is a very different code path than networking with epoll, and so far I've been disappointed to find it roughly 20% slower than my userspace thread pool doing the same thing for that task. Most likely there is some tweak to batching and maybe SQE submission watermarks, but I haven't found the formula yet. I was surprised to find the sqpoll thread spins instead of a fast timer. Seems like a contention problem on a single core system, which still exist in VMs, etc.