Epoll and Kqueue: How Operating Systems Learned to Wait Efficiently

One thing I find fascinating about epoll/kqueue is how much modern async frameworks abstract away the underlying readiness model.

A lot of people talk about “async performance” without realizing the core efficiency gain came from avoiding O(n) scans on idle FDs.

Curious how many higher-level runtimes still leak edge-triggered vs level-triggered semantics in subtle ways.