[openstack-dev] [nova] RT/Scheduler summit summary and Kilo development plan

Jay Pipes jaypipes at gmail.com
Mon Nov 17 15:58:52 UTC 2014

Good morning Stackers,

At the summit in Paris, we put together a plan for work on the Nova 
resource tracker and scheduler in the Kilo timeframe. A large number of 
contributors across many companies are all working on this particular 
part of the Nova code base, so it's important that we keep coordinated 
and updated on the overall efforts. I'll work together with Don Dugger 
this cycle to make sure we make steady, measured progress. If you are 
involved in this effort, please do be sure to attend the weekly 
scheduler IRC meetings [1] (Tuesdays @ 1500UTC on #openstack-meeting).

== Decisions from Summit ==

The following decisions were made at the summit session [2]:

1) The patch series for virt CPU pinning [3] and huge page support [4] 
shall not be approved until nova/virt/hardware.py is modified to use 
nova.objects as its serialization/domain object model. Jay is 
responsible for the conversion patches, and this patch series should be 
fully proposed by end of this week.

2) We agreed on the concepts introduced by the resource-objects 
blueprint [5], with a caveat that child object versioning be discussed 
in greater depth with Jay, Paul, and Dan Smith.

3) We agreed on all concepts and implementation from the 2 
isolate-scheduler-db blueprints: aggregates [6] and instance groups [7]

4) We agreed on implementation and need for separating compute node 
object from the service object [8]

5) We agreed on concept and implementation for converting the request 
spec from a dict to a versioned object [9] as well as converting 
select_destinations() to use said object [10]

[6] We agreed on the need for returning a proper object from the virt 
driver's get_available_resource() method [11] but AFAICR, we did not say 
that this object needed to use nova/objects because this is an interface 
internal to the virt layer and resource tracker, and the ComputeNode 
nova.object will handle the setting of resource-related fields properly.

[7] We agreed the unit tests for the resource tracker were, well, 
crappy, and are a real source of pain in making changes to the resource 
tracker itself. So, we resolved to fix them up in early Kilo-1

[8] We are not interested in adding any additional functionality to the 
scheduler outside already-agreed NUMA blueprint functionality in Kilo. 
The goal is to get the scheduler fully independent of the Nova database, 
and communicating with nova-conductor and nova-compute via fully 
versioned interfaces by the end of Kilo, so that a split of the 
scheduler can occur at the start of the L release cycle.

== Action Items ==

1) Jay to propose patches that objectify the domain objects in 
nova/virt/hardware.py by EOB November 21

2) Paul Murray, Jay, and Alexis Lee to work on refactoring of the unit 
tests around the resource tracker in early Kilo-1

3) Dan Smith, Paul Murray, and Jay to discuss the issues with child 
object versioning

4) Ed Leafe to work on separating the compute node from the service 
object in Kilo-1

5) Sylvain Bauza to work on the request spec and select_destinations() 
to use request spec blueprints to be completed for Kilo-2

6) Paul Murray, Sylvain Bauza to work on the isolate-scheduler-db 
aggregate and instance groups blueprints to be completed by Kilo-3

7) Jay to complete the resource-objects blueprint work by Kilo-2

8) Dan Berrange, Sahid, and Nikola Dipanov to work on completing the CPU 
pinning, huge page support, and get_available_resources() blueprints in 

== Open Items ==

1) We need to figure out who is working on the objectification of the 
PCI tracker stuff (Yunjong maybe or Robert Li?)

2) The child object version thing needs to be thoroughly vetted. 
Basically, the nova.objects.compute_node.ComputeNode object will have a 
series of sub objects for resources (NUMA, PCI, other stuff) and Paul 
Murray has some questions on how to handle the child object versioning 

3) Need to coordinate with Steve Gordon, Adrian Hoban, and Ian Wells  on 
NUMA hardware in an external testing lab that the NFV subteam is working 
on getting up and running [12]. We need functional tests (Tempest+Nova) 
written for all NUMA-related functionality in the RT and scheduler by 
end of Kilo-3, but have yet to divvy up the work to make this a reality.

== Conclusion ==

Please everyone read the above thoroughly and respond if I have missed 
anything or left anyone out of the conversation. Really appreciate 
everyone coming together to get this work done over the next 4-5 months.


[2] https://etherpad.openstack.org/p/kilo-nova-scheduler-rt
[3] https://review.openstack.org/#/c/129606/
[4] https://review.openstack.org/#/c/129608/
[5] https://review.openstack.org/#/c/127609/
[6] https://review.openstack.org/#/c/89893/
[7] https://review.openstack.org/#/c/131553/
[8] https://review.openstack.org/#/c/126895/
[9] https://review.openstack.org/#/c/127610/
[10] https://review.openstack.org/#/c/127612/
[11] https://review.openstack.org/#/c/133728/

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