On Jul 4, 2013, at 16:04 , Peter V. Saveliev <p...@redhat.com> wrote:

> …
> Goal
> ====
> We have to implement a feature, migration progress bar in the UI. This 
> migration bar should reflect not only the progress, but if the migration is 
> stalled and so on.
> Tasks
> =====
> * Get the information from libvirt: it provides job progress in the same way 
> for all migration-like jobs: migration, suspend, snapshot
> * Feed this information to the engine
> * Reflect it in the UI
> API status
> ==========
> Libvirt info is OK — it is available for any migration-like job, be it 
> migration, suspend or snapshot.
> In VDSM, we have an API call, a separate verb to report the migration 
> progress: migrateStatus()
> But also we have getVmList() call, polled by the engine every several seconds.
> Proposal
> ========
> We would propose to provide an optional field, `migrateStatus`, in the report 
> sent by getVmList(). This approach should save a good amount of traffic and 
> ease the engine side logic.
> Having the separate verb, this can sound weird, but I'm sure that the 
> optimisation worth it.
> Please, read the patchset [1] and discuss it here.

From my point of view this makes sense as it doesn't require additional 
bandwidth and calls.
Also means no additional complexity in engine. I don't feel comfortable to add 
another poll request during migration which makes the logic in engine more 
complicated and means even higher traffic between hosts and engine. Not that 
it's not doable, I just don't think it's the right way to go. I agree it's not 
ideal from purely API point of view...however to me it seems logical to have it 
as part of statistics as it is a sort of statistic, and it doesn't require an 
extra call. The extra call already exist, it's just that I think we already 
have too many. We should start looking into effective communication, not 
necessarily clean 


> Thanks.
> [1] http://gerrit.ovirt.org/#/c/15125/
> -- 
> Peter V. Saveliev
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