openstack team mailing list archive

[Huang Zhiteng <winston.d@xxxxxxxxx>]

On Tue, Oct 9, 2012 at 10:52 PM, Jonathan Proulx <jon@xxxxxxxxxxxxx> wrote:
> Hi All,
>
> Looking for a sanity test before I file a bug.  I very recently
> upgraded my install to Folsom (on top of Ubuntu 12.04/kvm).  My
> scheduler settings in nova.conf are:
>
> scheduler_available_filters=nova.scheduler.filters.standard_filters
> scheduler_default_filters=AvailabilityZoneFilter,RamFilter,CoreFilter,ComputeFilter
> least_cost_functions=nova.scheduler.least_cost.compute_fill_first_cost_fn
> compute_fill_first_cost_fn_weight=1.0
> cpu_allocation_ratio=1.0
>
> This had been working to fill systems based on available RAM and to
> not exceed 1:1 allocation ration of CPU resources with Essex.  With
> Folsom, if I specify a moderately large number of instances to boot or
> spin up single instances in a tight shell loop they will all get
> schedule on the same compute node well in excess of the number of
> available vCPUs . If I start them one at a time (using --poll in a
> shell loop so each instance is started before the next launches) then
> I get the expected allocation behaviour.
>
Per my understanding, this shouldn't happen no matter how (fast) you
create instances since the requests are queued and scheduler updates
resource information after it processes each request.  The only possibility
may cause the problem you met that I can think of is there are more than
 1 scheduler doing scheduling.
> I see https://bugs.launchpad.net/nova/+bug/1011852 which seems to
> attempt to address this issue but as I read it that "fix" is based on
> retrying failures.  Since KVM is capable of over committing both CPU
> and Memory I don't seem to get retryable failure, just really bad
> performance.
>
> Am I missing something this this fix or perhaps there's a reported bug
> I didn't find in my search, or is this really a bug no one has
> reported?
>
> Thanks,
> -Jon
>
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-- 
Regards
Huang Zhiteng