The author of the benchmark here. I went over some comments and I'll try to tackle them here. I'm pretty clear that GH runner based benchmark is far from perfect due to noisy neighbours etc. Thus every test first is running so called calibration... to reject completely unreliable VMs. I'm fully aware that this can't completely fix the issue. Can limit it but not fix. But as of now there are 593 runs recorded so average should still be quite meaningful.

Having that said I'm desperately trying to get REAL hardware to run that benchmark. With some successes ;)

Few months ago I got Hetzner machine from Kent Overstreet and I was able to finish 3 runs before machine died... Results: https://bartosz.fenski.pl/modern-fs-benchmark/real-hw/

Currently I've got even more interesting machine with tons of disks and I'm running new set of benchmarks but it's really in its initial stage.

https://bartosz.fenski.pl/modern-fs-benchmark/sas-hdd/ 2nd run in progress... one run on REAL hardware takes much more time than on GH runner so it's slow.

But this new hardware has also so many disks that the plan is to try also more complex, tiered cache topologies. I'm working on it.

I'm happy to answer any other questions, sources of every piece of this benchmark are freely available and I'm not saying they are 100% correct. I'm open to improvements.