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

On Wed, Jul 5, 2017 at 9:36 PM, Shirly Radco <sradco(a)redhat.com&gt; wrote: > > > -- > > SHIRLY RADCO > > BI SOFTWARE ENGINEER, > > Red Hat Israel <https://www.redhat.com/> > > sradco(a)redhat.com > <https://red.ht/sig> > <https://redhat.com/summit> > > > On Wed, Jul 5, 2017 at 6:35 PM, Arik Hadas <ahadas(a)redhat.com&gt; wrote: > >> >> >> On Wed, Jul 5, 2017 at 5:57 PM, Roy Golan <rgolan(a)redhat.com&gt; 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. > Ack. So if the proposed change is done, it would probably make sense to increase the inverval of those queries to be higher than 30 sec, or at least taking into consideration the _update_date of vm_statistics as well.

> >> 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 >>> >> >>> >>> _______________________________________________ >>> Devel mailing list >>> Devel(a)ovirt.org >>> http://lists.ovirt.org/mailman/listinfo/devel >>> >> >> >> _______________________________________________ >> Devel mailing list >> Devel(a)ovirt.org >> http://lists.ovirt.org/mailman/listinfo/devel >> > > _______________________________________________ Devel mailing list Devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/devel