Observation

For a direct I/O file system I/O workload, the relocation times are much lower than for the page cache file system I/O workload.

On the other hand, the quiesce times in the direct I/O fio case are in the same range as those in the page cache case, with the difference rising as higher preset fio throughputs are set.

For the direct I/O file system I/O workload, relocation as well as quiesce times stay almost constant while the throughput is preset; only with the maximum data rate (when no preset fio throughput is set) the quiesce time is about twice as high as that observed with a preset fio throughput.

A side observation is that the maximum data rate (when no preset fio throughput is set) with direct I/O (708 MiB/s) is only insignificantly smaller than with page cache I/O (716 MiB/s).