Reading Architecture of Open Source Applications chapter on nginx: http://aosabook.org/en/nginx.html
It references Kegel's C10K page, which, several years ago, was the spark that led to understanding many of the layers below the code I wrote, leading to a wealth of knowledge on topics like non-blocking IO with select/poll/epoll, TCP corking, TCP no delay, and fun Linux syscalls like sendfile, readv/writev, and so much more.
http://www.kegel.com/c10k.html
It was a great reference at the time.
A lot of the chapters in AoSA discuss dealing with disk IO a lot.
Optimising a web server (or any multi-threaded system) for the disks you have is crucial, and not a thing you can hand-wave and ignore, as often happens now in the containerised world as these things get abstracted away even further from the developer.
It will eventually result in performance cancer.
