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[openstack-dev] [nova] placement/resource providers update 33

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Here's update 33.

RC2 went to the presses. The result is that we've now got claims
happening earlier and using better information. This ought to mean
that there are fewer retries and failed builds. There's some
cruftiness in the code that manages allocations that will need to be
cleaned up, and bugs and buglets keep getting found in some edge cases
but overall much forward progress. Nice work everyone.

One alternate destinations is done, the next things coming up are
getting shared providers working on the nova side, incorporating
traits in resource requests, and, eventually, nested resource providers.

Presumably at the PTG we'll decide the if/when/how of extracting
placement to its own repo.

This week I've added a section that references bugs that have not yet
seen much action.

Most Important

Besides reviewing all the stuff in this document, another important
thing to do is to make additions and edits on the PTG etherpad (see
help wanted).

The ongoing work with allocation related functional tests (many listed
below), and the getting alternate destinations working is also
important.

Help Wanted

There's a swathe of placement related stuff on the PTG planning
etherpad. Please add to that or make some adjustments if you think
something is missing or incomplete:

  https://etherpad.openstack.org/p/nova-ptg-queens

An important aspect of this is determining what kind of dependency
tree is involved with the work.

Also see this new next section.

Bugs needing attention

(Bugs which are not yet in progress or beyond.)

Current

Old (need to be flushed or refreshed:?)

Docs

There's a stack that documents (with visual aids!) the flow of
scheduler and placement. It is pretty much ready:

 https://review.openstack.org/#/c/475810/

Main Themes

Alternate Destinations

There's a stack beginning at https://review.openstack.org/#/c/486215/
which proposes the bits necessary to return alternate destinations
besides the claimed destination. These will be used to do within-cell
(v2) retries in case a build can't be done on the claimed destiantion.

The spec revision for that work: https://review.openstack.org/#/c/471927/

Ed has some concerns about the complexity being created, so he wrote
up some issues at:

 https://blog.leafe.com/handling-unstructured-data/

In his response to https://review.openstack.org/#/c/495854/3 Jay
suggests a named tuple:

 I'm struck that instead of a two-tuple, both elements of the tuple
 having lists of lists, would it not be clearer to have the return
 value from select_destinations() instead be a single list of
 namedtuple elements, where the namedtuple would have a
 chosen_host, alternate_hosts, and allocation_requests attribute

Traits

Work continues apace on getting filtering by traits working:

   https://review.openstack.org/#/c/489206/

This has some overlap with shared provider handling (below).

Shared Resource Providers

There's some support for shared resource providers on the placement
side of the scheduling equation, but the resource tracker is not yet
ready to support it. There is some work in progress, starting with
functional tests:

  https://review.openstack.org/#/c/490733/

Nested Resource Providers

This will start back up after we clean off the windscreen. The stack
begins at https://review.openstack.org/#/c/470575/5

Other Code

--
Chris Dent (⊙_⊙') https://anticdent.org/
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asked Aug 28, 2017 in openstack-dev by cdent_plus_os_at_ant (12,800 points)   2 2 6

3 Responses

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On 8/25/2017 7:54 AM, Chris Dent wrote:

There's a stack that documents (with visual aids!) the flow of
scheduler and placement. It is pretty much ready:

https://review.openstack.org/#/c/475810/

I see I am late to the party here, but I've left comments in the
now-merged patch.

There are some issues with this, mainly around the fact this is talking
about scheduling, as I expect it to work today when I came into reading
this, but it's talking in detail about the alternatives stuff which was
not implemented in Pike, so I think that should be removed, or amended
with a big fat note that it's not available yet and anything to do with
alternatives is future work.

--

Thanks,

Matt


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responded Aug 28, 2017 by mriedemos_at_gmail.c (15,720 points)   2 5 11
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On 8/28/2017 5:09 PM, Matt Riedemann wrote:
There are some issues with this, mainly around the fact this is talking
about scheduling, as I expect it to work today when I came into reading
this, but it's talking in detail about the alternatives stuff which was
not implemented in Pike, so I think that should be removed, or amended
with a big fat note that it's not available yet and anything to do with
alternatives is future work.

Since patches are welcome, I've put forth a patch:

https://review.openstack.org/#/c/498613/

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Thanks,

Matt


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responded Aug 28, 2017 by mriedemos_at_gmail.c (15,720 points)   2 5 11
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On 8/25/2017 7:54 AM, Chris Dent wrote:
* https://bugs.launchpad.net/nova/+bug/1712411
Allocations may not be removed from dest node during failed migrations

Started with the functional recreate test patch:

https://review.openstack.org/#/c/498627/

--

Thanks,

Matt


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responded Aug 29, 2017 by mriedemos_at_gmail.c (15,720 points)   2 5 11
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