Hussain: Lord of the io_uring

Shuveb Hussain has posted an extensiveintroduction to io_uring, complete with examples and a reference guide."Because of the shared ring buffers between the kernel and userspace, io_uring can be a zero-copy system. Copying bytes around becomesnecessary when there are system calls that transfer data between kernel anduser space are involved. But since the bulk of the communication inio_uring is via buffers shared between the kernel and user space, this hugeperformance overhead is completely avoided."