[Wg-openstack] Minutes from Sept 21 Openstack WG meeting

[Lars Kurth <lars.kurth@xxxxxxxxxx>]

@ Andy: there is some stuff related to CPUID levelling, which is why you
are CC'ed

== Attendees ==
Joao Martins (Oracle)
Cedric Bosdonnat (SUSE)
Anhtony Perard (Citrix)
Jim Fehlig (SUSE)
Lars Kurth (Citrix)

== Introductions ==
Lars: Xen project community manager, and advisory board chairman
Joao: Working on Xen and Oracle Products based on Xen. Working on libvirt
and networking IO
Cedric: Jumped into libvirt and containers 3 years, libgustfs, libxl
driver together with Jim (SUSE)
Antony: QEMU, OpenStack CI loop, OpenStack work (on the side) (SUSE)
Jim: Suse, occasional Xen upstream contributor, libvirt contributor

== Agenda ==

=== New libvirt libxl features since last call ==
See 
https://www.youtube.com/watch?v=rSXb1g4rJ3w&list=PLYyw7IQjL-zEcw-9M5YWzAwXj
9mlOKZnU&index=4

Jim: 
Cinder volumes backed by ceph are now supported
May need to look at Tempest tests to see whether there are such tests
May need to upgrade what we test

Lars: do we have a list of tests that are disabled
Joao: posted some time ago on the list

ACTION: Joao will have a look and check what could be enabled and whether
libvirt + Xen needs to be upgraded in the CI loop

=== libvirt libxl features in progress or planned ===

==== In progress features

Port for XenChannels (Joao) :
allows sys prepping type activities to guess agents and cloud tools.

Joao: will be sending another version (today or tomorrow)



==== Planned features

* Guest agent commands using the Channels functionality
Joao: qemu-agent support is deferred to the next release
Joao: as far is I am aware, Nova uses missing qemu-agent APIs in
setuserpassword, snapshot, freeze and thaw ...

Lars: may be able to re-enable some tests with a newer version.
Joao: May need to update the CI loop to use newer

* Status update on CPUID support :
Joao had a series which was committed which propagates more CPU info
(sockets, ... , host and CCPU capabilities). Next step is to wire up this
in libxl.
Jim: wanted to check whether Joao is doing anything in this area (up to
Xen 4.7)
Joao: now we are supporting strictly host passthrough mode. The levelling
part still requires some work on libxl. Am experimenting and speccing out
these features. Will post on xen-devel. Implementing full policy support
on libxl coordinating with Andy Cooper.

* CPUID levelling at DevSummit:
https://www.youtube.com/watch?v=vb3RrjiZckw&index=23&list=PLYyw7IQjL-zEcw-9
M5YWzAwXj9mlOKZnU


Lars: CC Wei and Andy to ask what CPUID and start coordinating to see
whether this is something we can get into Xen 4.9

* Feature / Bug ... Deadlock in libvirt caused by libxl
Jim: was surprised that an upstream bug report (1 a year ago, again one 2
months ago which essentially encounters a deadlock in libvirt caused by
libxl). 
Had a fix for this: then forgot about it, but working on it again

Jim: Any observation of libvirtd deadlock in the CI loop?
Anthony: Have not seen anything
Jim: can be reproduced under heavy load test (needs lots of save/restore
in parallel and it will take days to see it). Just be aware that if there
are instances where libvirtd is locked up, Jim is working on it

* Jim: misc items not necessarily relevant for OpenStack
OpenVSwitch in Xen: not sure whether this is a big deal for OpenStack
USB (PV, Emulated, ...): and a few others

* Other planned / ongoing work

Bob: is working on turnoff migration (default enabled on openstack P2P
migration). Expect to see patches at some point. Also working on other
stuff.

Joao: multi-serial support went into libvirt 2.2. Does not look relevant,
but is relevant for HVM guests and OpenStack. When you get an empty file,
you get an empty console. Allows us to behave more like Nova. 1st serial
is written to a file, the 2nd serial is written to the console.

* Any outstanding libvirt libxl patches

None

* Upcoming deadlines:
4.8 freeze coming: Sept 30


=== Stuck stuff ===

* https://bugs.launchpad.net/nova/+bug/1450465 (no-one looking at that)
Joao: not sure how this can be fixed
Joao: on some Nova releases this works, but with Neutron it doesn't work
Joao: issue with OpenStack assumptions
Jim: The only way it solve this is to increase the buffer size
Joao: any Xen related fix would create a backwards compatibility issue
Jim: not able to specify "want to have PV only", "want to have" ... the
default getting both to os hard to change the default ...
Jim: instance fails to start because the name is too long we fail the
whole thing
Joao: name is taken straight from a UID

ACTION: Lars it chat to Bob Ball / Platform Team to see whether how XS is
working around this or whether there is a way to fix this

* https://review.openstack.org/#/c/264101/ (abandoned, but maybe shouldn't
be - see Jim's last comment)
Similar set of backwards compatibility issues
Using pygrub in cloud environments does not seem wise
Certain instance types don't work with PVGRUB ...
Would have to look into how Nova uses this stuff
Identify what issues we would face with PVGRUB only
Joao: Doesn't Daniel Berrange have a voting opinion on this?
Joao: Patch doesn't look intrusive and doesn't need to be the default.
Seems quite harmless for normal users.
Lars: Thomas is a SUSE employee - maybe Jim, Cedric ...can

* https://review.openstack.org/#/c/201257/
Lars to follow up with Bob Ball to see what needs to be done to get this
in shape, given that Bob voted -1

=== Documentation ===

ACTION: all review 
http://docs.openstack.org/mitaka/config-reference/compute/hypervisor-xen-li
bvirt.html and let Lars know whether we need to update docs

Lars is happy to do this

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