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

On 09/21/2016 11:25 AM, Lars Kurth wrote:
> @ 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).

For example, Joao's work added the following to host capabilities

      <topology sockets='2' cores='12' threads='2'/>
      <feature name='ds'/>
      <feature name='acpi'/>
      <feature name='ht'/>
      <feature name='tm'/>
      <feature name='pbe'/>
      <feature name='dtes64'/>
      <feature name='monitor'/>
      <feature name='ds_cpl'/>
      <feature name='vmx'/>
      <feature name='smx'/>
      <feature name='est'/>
      <feature name='tm2'/>
      <feature name='xtpr'/>
      <feature name='pdcm'/>
      <feature name='pcid'/>
      <feature name='dca'/>
      <feature name='xsaveopt'/>
      <feature name='pdpe1gb'/>
      <feature name='invtsc'/>

His work also included support for 'virsh cpu-compare' and 'virsh cpu-baseline'.
cpu-compare can be used to determine if the host's cpu is compatible with a cpu
described in an XML file (e.g. collected from another host). cpu-baseline can be
used to compute a baseline cpu from an XML file containing several host cpu
descriptions. So we are now able to compare host cpus to see if they are
compatible and compute a baseline cpu from a collection of host cpu
descriptions. What remains is the ability to control the guest cpu description.

>  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

Patch posted upstream that is working fine in my test setup


Looking forward to feedback from the upstream reporters.

> * 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

I did a quick read and didn't notice anything wrt version numbers, know issues,
etc. that needs updated.


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