With the caveat that I have not looked at this in over a decade, readahead via madvise() is imprecise to the point of near uselessness for high-throughput datab

With the caveat that I have not looked at this in over a decade, readahead via madvise() is imprecise to the point of near uselessness for high-throughput database workloads. The biggest issue is that, as the name implies, Linux is free to ignore madvise() or do something that is not quite what you requested, and often does. Many types of finely choreographed locality optimizations require more determinism than it offers.