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On 11/14/2012 04:55 PM, Eoghan Glynn wrote:
> 
> 
> ----- Original Message -----
>> I'm partial to #3 on the basis that it would encourage us to expose
>> more useful information to the world. I don't think that would mean
>> Ceiliometer is leaking into Nova, we're just exposing data that
>> consumers are asking for.
>>
>> I might be missing something silly, but why does Nova need to know
>> where Ceiliometer's message bus is? Why can't Ceiliometer just
>> listen on the queue wherever Nova, Glance, Cinder, etc are already
>> producing notifications?
> 
> Sure, but that's not so much the issue I had in mind.
> 
> Its more that nova would have to start becoming concerned with the
> semantics of stats that ceilometer currently interprets. For example,
> nova might need to know how to derive say CPU utilization from the
> cumulative CPU time samples reported by the hypervisor driver.
> 
> So, its not knowledge of the ceilo queues leaking into nova that I'd
> be concerned about, more leakage of ceilo logic.

Why does nova have to do that logic?  That can't be done on the
notification consumption side?  If it can't be done on the consumption
side, then I think it seems fair to put it in nova.

What are the performance differences with this approach vs options 1 and
2?  If performance is a major concern, then an event based approach
seems like it could be more efficient.  Or is there a reason a poll
approach is needed?

-- 
Russell Bryant