On 03/09/2012 12:42 PM, Eric Blake wrote: > On 03/09/2012 11:53 AM, Anthony Liguori wrote: >>>> >>>> Could we just remove block migration entirely... >>> >>> Libvirt has already exposed block migration to users, >> >> :-( >> >> Do you rely on the progress stats that are printed? > > I've never personally used it (as I said earlier, the libvirt support > for blk and inc doesn't get much testing), but I can state that if you do: > > virsh migrate --copy-storage-all --copy-storage-inc --verbose ... > > that virsh will cause libvirt to start up a detached migration, then > repeatedly call the query-migrate monitor command to update an on-screen > progress monitor to the user; this progress monitor tracks both ram and > disk status to compute the percentage complete showed to the user, so at > some level, libvirt really is trying to rely on accurate block migration > progress numbers.
Just realized I wasn't very clear: libvirt does _not_ play back qemu's status numbers, so much as computing its _own_ progress monitor based on parsing the output of the repeated query-migrate commands. And since libvirt tends to favor QMP over HMP, the only monitoring we need from QMP is what we query for; we don't need HMP-style update messages. Having HMP update a progress line each time it rearms the one second timer while waiting for the migration to complete is probably good enough for HMP, and libvirt won't care. -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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