The author is upgrading their Chumby 8’s Linux kernel and notices high CPU usage with top. They go through various theories and experiments to troubleshoot the issue. The author eventually realizes they don’t understand how top calculates CPU usage and dives into BusyBox’s source code to grasp the process. They find that top uses procfs to gather CPU stats and calculates load based on differences in values from /proc/stat. Through experiments, the author confirms their understanding, discovering that /proc/stat data reflects CPU activity accurately. This fresh angle leads them closer to solving the CPU usage mystery in their upgraded kernel.
https://www.downtowndougbrown.com/2024/04/why-is-my-cpu-usage-always-100-upgrading-my-chumby-8-kernel-part-9/