epoll and kqueue: How Operating Systems Learned to Wait Efficiently
Summary
This article explains how epoll on Linux and kqueue on BSD/macOS enable scalable I/O by notifying the application about events rather than polling all file descriptors. It covers the problems with traditional polling, the core idea of registering interest once, and how Go uses these mechanisms to implement a non blocking network scheduler for high concurrency. It also contrasts level triggered and edge triggered modes and highlights how epoll and kqueue have transformed building scalable servers.