OpenStack Compute (nova)

Enabled qemu memory balloon stats when boot instance

Registered by Rui Chen

We can get vm memory stats from libvirt API 'virDomainMemoryStats', it help telemetry module like as: Ceilometer to collect vm memory usage, but by default the memory statistical feature is disable in qemu, we need to modify libvirt.xml in order to enabled memory statistical, like this:

    <memballoon model='virtio'>
      <stats period='10'/>
    </memballoon>

Add memballoon device and set period > 0 in libvirt.xml when boot instance.
Depends on libvirt 1.1.1+ and qemu 1.5+.

DocImpact:

1. If you want to use this feature, you need to add the option 'mem_stats_period=10' into nova.conf.

2. mem_stats_period is number of seconds to memory usage statistics period.

3. If you set mem_stats_period<=0, the memory stats will be disabled, by default mem_stats_period=10.

Refer to http://libvirt.org/html/libvirt-libvirt.html#virDomainMemoryStats for libvirt api details.
Refer to http://libvirt.org/formatdomain.html#elementsMemBalloon for memballoon details in libvirt.xml

Details of enabled memory stats:
http://paste.openstack.org/show/78624/

Blueprint information

Status:
Complete
Approver:
John Garbutt
Priority:
Low
Drafter:
Rui Chen
Direction:
Approved
Assignee:
Rui Chen
Definition:
Approved
Series goal:
Accepted for juno
Implementation:
Implemented
Milestone target:
milestone icon 2014.2
Started by
Rui Chen
Completed by
Thierry Carrez

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Gerrit topic: https://review.openstack.org/#q,topic:bp/enabled-qemu-memballoon-stats,n,z

Addressed by: https://review.openstack.org/92469
    Enabled qemu memory balloon stats

Spec not approved yet, un-targeting blueprint from juno-1 --johnthetubaguy (28th May 2014)

You should not set a milestone target unless the blueprint has been properly prioritized by the project drivers.
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Addressed by: https://review.openstack.org/106704
    Enabled qemu memory balloon stats

Just waiting for the last patch to merge now --johnthetubaguy 22nd July 2014

Arg, this no longer merges cleanly, so this is likely to be delayed, pushing to juno-3 --johnthetubaguy 22 July 2014

All patches in the gate, leaving in juno. --johnthetubaguy 2nd September 2014

(?)

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