[ovirt-devel] Chaning the statistics monitoring interval to 30s

[Shirly Radco]

--

SHIRLY RADCO

BI SOFTWARE ENGINEER,

Red Hat Israel <https://www.redhat.com/>

sradco at redhat.com
 <https://red.ht/sig>
 <https://redhat.com/summit>


On Wed, Jul 5, 2017 at 6:35 PM, Arik Hadas <ahadas at redhat.com> wrote:

>
>
> On Wed, Jul 5, 2017 at 5:57 PM, Roy Golan <rgolan at redhat.com> wrote:
>
>> Hi all,
>>
>> I would like to get feedback on $subject and see if I'm missing
>> something. The impact of this is simply less resource consumption and by
>> that we can support even greater number of hosts [1] and vms in the system.
>>
>
>> If you think more relaxed statistics collection will affect a core flow
>> let me know - as far as I see I didn't spot anything critical.
>>
>
>> The overhead of a cycle per host something like that: 2 roundtrips per
>> host in a cycle, (vm + host stats) and tons of memory allocation for char[]
>> -> json-> maps of maps -> VM/Vds statistics -> Maps -> serialiazing to DB.
>>
>> To minimize the effect of this change we can leave a call to 'list' verb
>> to at least detect vms existence in the same rate as today.
>>
>
> +1
>
>
>>
>> Pros
>> - Engine has rore resources to support more hosts/vms/other activities of
>> the engine
>> - Vdsm will have more resources as well (need to tweak vdsm to collect in
>> the same
>> frequency)
>> - less DB writes and reads, approx half of what the system will do in the
>> in its lifefpan (cause this is what is mainly does all the time)
>>
>> Cons
>> - DWH/Dashboard will have less entries, I'm not sure what is graphical
>> affect given our hourly resolution (cmiiw here)
>>
>
> What's the frequency of the queries done by DWH/Dashboard? Do they count
> on the _update_date column of the queried data?
>

Current frequency is 20 seconds.
The configurations are queried based on the _update_date, but  statistics
are queried every interval.

The affect will be less accuracy in the hourly calculations.


> I'm asking because if they query the database every minute and say "the
> time now is 10:30 and the queried data is ..." then there should not be
> less entries.
>
>
>>
>>
>> [1] https://bugzilla.redhat.com/show_bug.cgi?id=1430876
>>
>
>>
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>>
>
>
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