Epoll vs. Io_uring in Linux

First, I want to tell you how exactly I got to this point and why I started researching different options for handling asynchronous I/O on Linux... Last year, my students and I built a reverse proxy server called TinyGate. It was super simple, worker-based, and it basically worked well. Of course, I didn't expect it to be very fast, but it was an educational project, and since we'd made a real, kind of production-ready tool, I was really proud of it. But my students weren't as happy as I was - they wanted to build something genuinely useful, and they were really disappointed that our "product" had strong architectural limits and couldn't outperform titans like nginx and haproxy. So they literally forced me to research together how those tools work under the hood and how to handle asynchronous I/O to cut down on the heavy overhead... Long story short, we made a second version of TinyGate, based on epoll. It still lost to nginx/haproxy in benchmarks, but it had a dramatic performance boost compared to the first version. But epoll isn't perfect either (as I'll explain below), and we eventually switched to io_uring, which led to a full rewrite of our project from scratch, again... So it's a really interesting topic, and today I'll share an overview of the two queueing systems Linux gives you for asynchronous I/O.