Re: [libvirt] [PATCH v2 12/12] qemu: show disks stats for nbd migration

On 17.02.2017 13:17, Jiri Denemark wrote: > On Wed, Dec 28, 2016 at 17:39:21 +0300, Nikolay Shirokovskiy wrote: >> There is no disks stats when migrating with VIR_MIGRATE_NON_SHARED_* >> for qemu that supports nbd. The reason is that disks are copied via disk mirroring >> and not in the scope of migration job itself. Below >> a couble of issues of the implementation are described. >> >> 'total' field is set from 'end' field of block job info for the >> sake of simplicity. This is true only when there is no guest disk >> activity during migration. If there is an activity then 'end' will >> grow > > This is exactly how memory migration works too. > >> while 'total' is an estimation that should stay constant. > > Nope. That's the reason why migration is an unbounded job, we never know > what the total is and it is designed to change anytime during migration > as we realize more data needs to be transferred. > >> I guess this can be fixed by setting 'total' to disk 'capacity'. > > Nothing to fix really. Then I don't understand next passage from virDomainJobInfo definition. * For VIR_DOMAIN_JOB_UNBOUNDED, dataTotal may be less * than the final sum of dataProcessed + dataRemaining * in the event that the hypervisor has to repeat some * data, such as due to dirtied pages during migration. I thought total is initial estimation which never changed and processed and remaining are updated as we go. IIRC this is the case for memory migration.

> Otherwise the patch looks good and it's definitely cleaner than v1. > However, I think you should also update disk migration statistics while > stopping the mirror jobs so that the stats of a completed migration > contain accurate data. You mean after migration is completed there can be some disks transfers yet like buffered data? Ok.