Linux 4.17 I/O Scheduler Tests On An NVMe SSD Yield Surprising Results

When running the startup-time test profile that measures how long it takes to launch an application while there is I/O happening in the background, the results were quite surprising for this Optane SSD. MQ-Deadline, none, and BFQ yielded roughly the same performance but Kyber led to a slightly shorter start-up time for the GNOME Terminal, but most surprising was how much faster BFQ was when configured in its low-latency mode. Granted, when BFQ is in its low-latency mode, the throughput performance can be deprived in aiming for a lower latency.

With the startup-time test when there was still I/O happening in the background and measuring the time to initiate the LibreOffice Writer word processor, BFQ low_latency again delivered the shortest startup time for this program.

When mixing in background reads and writes, BFQ low-latency continued yielding the quickest start-up time for the program under test followed by the Kyber I/O scheduler -- both doing better than "none" along with MQ-Deadline. While BFQ in its normal latency mode was the slowest.