Zero-copy network transmission with io_uring

I'm really starting to warm to the concept of an exokernel as a high-performance solution. Just do away with all the kernel abstractions and system calls and even the message passing of a microkernel.

Two threads, one with access to the networking hardware and one from the application, communicating simultaneously through a lockless ring buffer in shared memory. If you ignore the fact that the former here is in kernelspace (in an exokernel userspace processes can be given direct hardware access) then this starts to look like that a lot.

Of course, in an exokernel you don't need the first thread that specializes in handling the network hardware if your webserver thread knows how to do it. Real examples exist.