io_uring, kTLS and Rust for zero syscall HTTPS server
Around the turn of the century we started to get a bigger need for high capacity web servers. For example there was the C10k problem paper.
At the time, the kinds of things done to reduce work done per request was pre-forking the web server. This means a request could be handled without an expensive process creation.
Because yes, creating a new process for every request was something perfectly normal.
Things did get better. People learned how to create threads, making things more
light weight. Then they switched to using poll()/select(), in order to not
just spare the process/thread creation, but the whole context switch.
I remember a comment on Kuro5hin from anakata, the creator of both The Pirate Bay and the webserver that powered it, along the lines of “I am select() of borg, resistance is futile”, mocking someone for not understanding how to write a scalable webserver.
But select()/poll() also doesn’t scale. If you have ten thousand
connections, that’s an array of ten thousand integers that need to be sent to
the kernel for every single iteration of your request handling loop.
Enter epoll (kqueue on other operating systems, but I’m focusing Continue reading
