[placement][ptg] Allocation Partitioning

Chris Dent cdent+os at anticdent.org
Mon Apr 8 14:25:07 UTC 2019


>From the etherpad [1]:

* do we need this?
* what is it?
* who is going to drive it?

As as I recall, allocation partitioning (distinct from
resource provider partitioning) is a way of declaring that a set of
allocations below to a specific service. This is useful as a way,
for example, of counting instances spawned via nova. Right now it is
possible to count vcpus, ram and disk but if something besides nova
is making allocations using those resource classes how do we
distinguish?

Of course it's important to also ask "should we distinguish?". If
there's a concept of unified limits does it matter whether a VCPU is
consume by _this_ nova or something else if they are consumed by the
same user?

This functionality is closely tied to resource provider
partitioning. In a complex placement scenario, where placement is
managing multiple instance spawning tools, in multiple cloud-like
things, it seems like both would be needed.

The ongoing work to implement quota counting in placement [2] has a
workaround for instances not being counted in placement, but the
"more than one nova per placement" limitation has to be documented.

How urgent is this? Is there anyone available to do the work this
cycle? How damaging is it to punt to U? What details are missing in
the above description?

[1] https://etherpad.openstack.org/p/placement-ptg-train
[2] https://review.openstack.org/#/q/topic:bp/count-quota-usage-from-placement

-- 
Chris Dent                       ٩◔̯◔۶           https://anticdent.org/
freenode: cdent                                         tw: @anticdent


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