Comment 19 for bug 1847105

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In , paelzer (paelzer-redhat-bugs) wrote :

Hi Daniel,
yes falloc should be fast in many cases, but also isn't in others.

The reporter used this directly on a ZFS system.
I used to recreate the slowness on stacked containers which is EXT4 -> ZFS-image file -> LXD container -> libvirt.
So far it seems we can assume that ZFS is slow in this use case.

I agree that on ext4 and tmpfs this is <0.02 real time.
So to face the slowdown might have a ZFS component.