Another one is I could not find a benchmark with io_uring - this would confirm the benefit of going from epoll.
One of the advantages of io_uring, unrelated to performance, is that it supports non-blocking operations on blocking file descriptors.
Using io_uring is the only method I recall to bypass https://gitlab.freedesktop.org/wayland/wayland/-/issues/296. This issue deals with having to operate on untrusted file descriptors where the blocking/non-blocking state of the file descriptions might be manipulated by an adversary at any time.
For sockets, `MSG_DONTWAIT` works with both `recv` and `send`.
For pipes you should be able to do this with `SPLICE_F_NONBLOCK` and the `splice` family, but there are weird restrictions for those.
Certainly not; it's likely to make it run faster, since you can use the elevator algorithm more efficiently instead of seeking back and forth between the files. You can easily measure this yourself by using comparing wcp, which uses io_uring, and GNU cp (remember to empty the cache between each run).