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Placement Update 18-30

This is placement update 18-30, a weekly update of ongoing development related to the OpenStack placement service.

Most Important

This week is feature freeze for the Rocky cycle, so the important stuff is watching already approved code to make sure it actually merges, bug fixes and testing.

What's Changed

At yesterday's meeting it was decided the pending work on the /reshaper will be punted to early Stein. Though the API level is nearly ready, the code that exercises it from the nova side is very new and the calculus of confidence, review bandwidth and gate slowness works against doing an FFE. Some references:

Meanwhile, pending work to get the report client using consumer generations is also on hold:

As far as I understand it no progress has been made on "Effectively managing nested and shared resource providers when managing allocations (such as in migrations)."

Some functionality has merged recently:

  • Several changes to make the placement functional tests more placement oriented (use placement context, not be based on nova.test.TestCase).
  • Add 'nova-manage placement sync_aggregates'
  • Consumer generation is being used in heal allocations CLI
  • Allocations schema no longer allows extra fields
  • The report client is more robust about checking and retrying provider generations.
  • If force_hosts or force_nodes is being used, don't set a limit when requesting allocation candidates.


I wrote up some analysis of the way the resource tracker talks to placement. It identifies some redundancies. Actually it reinforces that some redundancies we've known about are still there. Fixing some of these things might count as bug fixes. What do you think?


Main Themes


Now that we are feature frozen we better document all the stuff. And more than likely we'll find some bugs while doing that documenting.

This is a section for reminding us to document all the fun stuff we are enabling. Open areas include:

  • "How to deploy / model shared disk. Seems fairly straight-forward, and we could even maybe create a multi-node ceph job that does this - wouldn't that be awesome?!?!", says an enthusiastic Matt Riedemann.

  • The whens and wheres of re-shaping and VGPUs.

  • Please add more here by responding to this email.

Consumer Generations

These are in place on the placement side. There's pending work on the client side, and a semantic fix on the server side, but neither are going to merge this cycle.

Reshape Provider Trees

On hold, but still in progress as we hope to get it merged as soon as there is an opportunity to do so:

It's all at:

Mirror Host Aggregates

The command line tool merged, so this is done. It allows aggregate-based limitation of allocation candidates, a nice little feature that will speed things up for people.


I wrote up a second blog post on some of the issues associated with placement extraction. There are several topics on the PTG etherpad related to extraction.


Since we're at feature freeze I'm going to only include things in the list that were already there and that might count as bug fixes or potentially relevant for near term review.

So: 11, down from 29.


Lots to review, test, and document.

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