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Btrfs/ZFS/bcachefs under workloads classic benchmarks skip

179 points · 190 comments · farlight

  1. Farmadupe · · focus · HN ↗
    > CI runs use loop devices on shared ephemeral VMs (one VM per filesystem): compare shapes and ratios, not absolute MB/s. Each job records a host-calibration anchor — see the table.

    I think if you're not using baremetal for such tests, it's likely that the results are simply not comparable at all? What if another tenant is also using the disk?

    1. walrus01 · · focus · HN ↗
      It's a fair point but it's also possible the person running the tests has a dedicated test hypervisor for this , so that different configurations of filesystems and VMs can be created and destroyed quickly in an automated manner.

      If it's something as simple as a KVM hypervisor that only runs 1 test VM at a time (with no other load from anything else other than the basic systemd daemons, ssh daemon etc running on the hypervisor), the results could be very close to bare metal.

      I can see it being very time consuming and annoying to do repeated manual bare metal OS installs and new partitioning/filesystem creation for such a large variety of tests.

      The author does also say that performance isn't really the main thing but rather, data integrity:

      <a href="https:&#x2F;&#x2F;github.com&#x2F;fenio&#x2F;modern-fs-benchmark" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;fenio&#x2F;modern-fs-benchmark

      1. fenio · · focus · HN ↗
        For the main linked benchmark there are no dedicated test hypervisors. It&#x27;s all based on GH runners with all the limitations and quirks that came with it.

        Real hardware is used in: <a href="https:&#x2F;&#x2F;bartosz.fenski.pl&#x2F;modern-fs-benchmark&#x2F;real-hw&#x2F;" rel="nofollow">https:&#x2F;&#x2F;bartosz.fenski.pl&#x2F;modern-fs-benchmark&#x2F;real-hw&#x2F; <a href="https:&#x2F;&#x2F;bartosz.fenski.pl&#x2F;modern-fs-benchmark&#x2F;sas-hdd&#x2F;" rel="nofollow">https:&#x2F;&#x2F;bartosz.fenski.pl&#x2F;modern-fs-benchmark&#x2F;sas-hdd&#x2F;

        But unfortunatelly it&#x27;s much more limited number of actual runs. sas-hdd is still in progress so numbers for it should increase over time.

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