[placement] update 19-19
cdent+os at anticdent.org
Fri May 17 15:34:13 UTC 2019
Woo! Placement update 19-19. First one post PTG and Summit. Thanks
to everyone who helped make it a useful event for Placement. Having
the pre-PTG meant that we had addressed most issues prior to getting
there meaning that people were freed up to work in other areas and
the discussions we did have were highly coherent.
Thanks, also, to everyone involved in getting placement deleted from
nova. We did that while at the PTG and had a little
# Most Important
We're still working on narrowing priorities and focusing the details
of those priorities. There's an
where we're taking votes on what's important. There are three specs
in progress from that that need review and refinement. There are two
others which have been put on the back burner (see specs section
# What's Changed
* We're now [running a
subset](https://review.opendev.org/657077) of nova's
functional tests in placement's gate.
* osc-placement is using the PlacementFixture to run its functional
tests making them _much_ faster.
* There's a set of StoryBoard
that can be used to help find in progress work and new bugs. That
section also describes how tags are used.
* There's a [summary of summaries](http://lists.openstack.org/pipermail/openstack-discuss/2019-May/006278.html)
email message that summarizes and links to various results from
As the summary of summaries points out, we have two major features
this cycle, one of which is _large_: getting consumer types going
and getting a whole suite of features going to support nested
providers in a more effective fashion.
Support Consumer Types. This is very close with a few details to
work out on what we're willing and able to query on. It only has
reviews from me so far.
Spec for Nested Magic. This is associated with a [lengthy
includes visual artifacts from the PTG. It covers several related
features to enable nested-related requirements from nova and
neutron. It is a work in progress, with several unanswered
questions. It is also something that efried started but will be
unable to finish so the rest of us will need to finish it up as
the questions get answered. And it also mostly subsumes a previous
spec on [subtree
affinity](https://review.opendev.org/#/c/650476/). (Eric, please
correct me if I'm wrong on that.)
Resource provider - request group mapping in allocation candidate.
This spec was copied over from nova. It is a requirement of the
overall nested magic theme. While it has a well-defined and
refined design, there's currently no one on the hook implement
There are also two specs that are still live but de-prioritized:
support any trait in allocation candidates
support mixing required traits with any traits
These and other features being considered can be found on the
Some non-placement specs are listed in the Other section below.
There are 23 stories in [the placement
0 are [untagged](https://storyboard.openstack.org/#!/worklist/580).
4 are [bugs](https://storyboard.openstack.org/#!/worklist/574). 5 are
[cleanups](https://storyboard.openstack.org/#!/worklist/575). 12 are
[rfes](https://storyboard.openstack.org/#!/worklist/594). 2 are
If you're interested in helping out with placement, those stories
are good places to look.
* Placement related nova [bugs not yet in progress](https://goo.gl/TgiPXb)
on launchpad: 16. +3
* [In progress placement bugs](https://goo.gl/vzGGDQ) on launchpad: 6.
+2. These are placement-related, in nova.
Of those there two interesting ones to note:
nova placement api non-responsive due to eventlet error.
When using placement-in-nova in stein, recent eventlet changes can
cause issues. As I've mentioned on the bug the best way out of
this problem is to use placement-in-placement but there are other
The allocation table has residual records when instance is evacuated
and the source physical node is removed.
This appears to be yet another issue related to orphaned
allocations during one of the several move operations. The impact
they are most concerned with, though, seems to be the common "When
I bring up a new compute node with the same name there's an
existing resource provider in the way" that happens because of the
unique constrain on the rp name column.
I'm still not sure that constraint is the right thing unless we want
to make people's lives hard when they leave behind allocations. We
may want to make it hard because it will impact quota...
osc-placement is currently behind by 11 microversions. No change
since the last report.
_Note: a few of these having been sitting for some time with my +2
awaiting review by some other placement core. Please remember
osc-placement when reviewing._
Add 'resource provider inventory update' command (that helps with
aggregate allocation ratios).
Add support for 1.22 microversion
Provide a useful message in the case of 500-error
Remove unused cruft from doc and releasenotes config
Improve aggregate version check error messages with min_version
Expose version error message generically
# Main Themes
Now that the PTG has passed some themes have emerged. Since the
Nested Magic one is rather all encompassing and Cleanup is a
catchall, I think we can consider three enough. If there's some
theme that you think is critical that is being missed, let me know.
For people coming from the nova-side of the world who need or want
something like review runways to know where they should be focusing
their review energy, consider these themes and the links within them
as a runway. But don't forget bugs and everything else.
## Nested Magic
At the PTG we decided that it was worth the effort, in both Nova and
Placement, to make the push to make better use of nested providers —
things like NUMA layouts, multiple devices, networks — while keeping
the "simple" case working well. The general ideas for this are
described in a [story](https://storyboard.openstack.org/#!/story/2005575)
and an evolving [spec](https://review.opendev.org/658510).
Some code has started, mostly to reveal issues:
Changing request group suffix to string
WIP: Allow RequestGroups without resources
Add NUMANetworkFixture for gabbits
Gabbi test cases for can_split
## Consumer Types
Adding a type to consumers will allow them to be grouped for various
purposes, including quota accounting. A
[spec](https://review.opendev.org/654799) has started. There are
some questions about request and response details that need to be
resolved, but the overall concept is sound.
As we explore and extend nested functionality we'll need to do some
work to make sure that the code is maintainable and has suitable
performance. There's some work in progress for this that's important
enough to call out as a theme:
Some work from Tetsuro exploring ways to remove redundancies in
the code. There's a [related WIP](https://review.opendev.org/658778)
Enhance debug logging in allocation candidate handling
Start of a stack that will allow us to remove the protections
against null root providers (which turns out is a pretty
significant performance hit).
WIP: Optionally run a wsgi profiler when asked.
This was used to find some of the above issues. Should we make it
generally available or is it better as a thing to base off when
Ed Leafe has also been doing some intriguing work on using graph
databases with placement. It's not yet clear if or how it could be
integrated with mainline placement, but there are likely many things
to be learned from the experiment.
# Other Placement
A suite of refactorings that given their lack of attention perhaps
we don't need or want, but let's be explicit about that rather
than ignoring the patches if that is indeed the case.
A start at some unit tests for the PlacementFixture which got lost
in the run up to the PTG. They may be less of a requirement now
that placement is running nova's functional tests. But again, we
should be explicit about that decision.
# Other Service Users
New discoveries are added to the end. Merged stuff is removed.
Nova: Spec: Proposes NUMA topology with RPs
Nova: Spec: Virtual persistent memory libvirt driver
Nova: Check compute_node existence in when nova-compute reports
info to placement
Nova: spec: support virtual persistent memory
Workaround doubling allocations on resize
Nova: Pre-filter hosts based on multiattach volume support
Nova: Add flavor to requested_resources in RequestSpec
Blazar: Retry on inventory update conflict
Nova: count quota usage from placement
Nova: nova-manage: heal port allocations
Nova: Spec for a new nova virt driver to manage an RSD
Cyborg: Initial readme for nova pilot
Tempest: Add QoS policies and minimum bandwidth rule client
Nova-spec: Add PENDING vm state
nova-spec: Allow compute nodes to use DISK_GB from shared storage RP
nova-spec: RMD Plugin: Energy Efficiency using CPU Core P-State control
puppet: Debian: Add support for placement-api over uwsgi
nova-spec: Proposes NUMA affinity for vGPUs. This describes a
legacy way of doing things because affinity in placement may be a
ways off. But it also [may not
Nova: heal allocations, --dry-run
Neutron: Fullstack test for placement sync
Watcher spec: Add Placement helper
Cyborg: Placement report
Nova: Spec to pre-filter disabled computes with placement
rpm-packaging: placement service
Delete resource providers for all nodes when deleting compute service
I'm out of practice on these things. This one took a long time.
Chris Dent ٩◔̯◔۶ https://anticdent.org/
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