On Fri, Oct 30, 2026 at 02:06:00AM +0100, Denis V. Lunev wrote: > Backup and commit re-query the source block status for every task and > size a task by the copy buffer, so a long run of zeroes turns into a > crowd of small write-zeroes requests. This series reuses what the > up-front scan already learned and lets one write-zeroes task cover a > whole run. > > Backup of a 16G qcow2 image holding 1G of data, the rest never > allocated, sync=full to a raw target on ext4: > > tasks time > before 16384 1.6s > after 1088 1.0s > > Such an image is the normal case rather than a corner one: a guest with > discard enabled on a disk which is mostly free leaves exactly this > shape behind. > > Eric, this is the v4 you asked about on 10-28; please take it instead > of v3.
Will do, thanks. Queueing up a pull request today. -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
