The Linux kernel contains a large number of tunables; these often take the form of sysctl(8) parameters, and are usually introduced for situations where there is no one "right" answer for a configuration choice. The number of tunables available is quite daunting. On a 6.2 kernel we see
At the same time, individual systems get a lot less care and adminstrator attention than they used to; phrases like "cattle not pets" exemplify this. Given the modern cloud architectures used for most deployments, most systems never have any human adminstrator interaction after initial provisioning; in fact given the scale requirements, this is often an explicit design goal - "no ssh'ing in!".
These two observations are not unrelated; in an earlier era of fewer, larger systems, tuning by administrators was more feasible.
A lot of lore accumulates around these tunables, and to help clarify why we developed bpftune, we will use a straw-man version of the approach taken with tunables: