[$] I/O scheduling for single-queue devices
Block I/O performance can be one of the determining factors for the
performance of a system as a whole, especially on systems with slower
drives. The need to optimize I/O patterns has led to the development of a
long series of I/O schedulers over the years; one of the most recent of
those is BFQ, which was merged during the
4.12 development cycle. BFQ incorporates an impressive set of heuristics
designed to improve interactive performance, but it has, thus far, seen
relatively little uptake in deployed systems. An attempt to make BFQ the
default I/O scheduler for some types of storage devices has raised some
interesting questions, though, on how such decisions should be made.