Thread

Btrfs/ZFS/bcachefs under workloads classic benchmarks skip

179 points · 190 comments · farlight

fenio · 1789847733 · focus · HN ↗
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: <a href="https://bartosz.fenski.pl/modern-fs-benchmark/real-hw/" rel="nofollow">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.
<a href="https://bartosz.fenski.pl/modern-fs-benchmark/sas-hdd/" rel="nofollow">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.
1. BoingBoomTschak · 1789916250 · focus · HN ↗
  Good job and clean website interface! Something as exhaustive as this is clearly needed.
  Some remarks:
  1. Why does the CoW button remove XFS from the list? Even <a href="https://github.com/fenio/modern-fs-benchmark/blob/main/scripts/fs/xfs.sh" rel="nofollow">https://github.com/fenio/modern-fs-benchmark/blob/main/scrip... mentions it has reflink enabled
  2. If you have the time, adding XFS + mdraid + dm-integrity [1] (in bitmap mode) as a comparison point against ZFS RAID-Zx might be an interesting data point. That's what I run, personally.
  3. Did you give some thoughts to the I/O scheduler choice? Might matter a lot in some cases.
  [1] <a href="https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/dm-integrity.html" rel="nofollow">https://www.kernel.org/doc/html/latest/admin-guide/device-ma...
  1. fenio · 1789924588 · focus · HN ↗
    Thanks, all three are fair points.
    1. XFS reflink is enabled and its reflink/CoW-break measurements do run. The dashboard button currently means “native/full-CoW filesystem family”, not “supports reflink”, but that distinction is not clear from the label. I’ll rename it to “Native CoW” and add a separate reflink-capable filter that includes XFS.
    2. The current integrity comparison is XFS on LVM/dm-raid10 with dm-integrity in its default journal mode. It is not mdraid and not bitmap mode, so your suggested stack would be a genuinely different and useful data point. An md RAID5/6 over per-member bitmap-mode dm-integrity comparison against RAID-Z1/Z2 makes sense, with the weaker post-crash bitmap semantics documented.
    3. I did not pin or record the scheduler, which is a reproducibility gap. The dedicated SAS machine currently has mq-deadline active on all HDDs and SSDs. I’ll add queue/scheduler metadata to results before considering separate scheduler variants, since it can strongly affect the mixed and latency-sensitive phases.

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