Bug 1371581 - Preserve the guest-stats-polling-interval property across migrations
Summary: Preserve the guest-stats-polling-interval property across migrations
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.4
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Jiri Denemark
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-08-30 14:13 UTC by Ladi Prosek
Modified: 2016-09-06 12:12 UTC (History)
2 users (show)

Fixed In Version:
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Last Closed: 2016-09-06 12:12:06 UTC
Target Upstream Version:

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Description Ladi Prosek 2016-08-30 14:13:04 UTC 
Description of problem:
This is a QEMU-specific problem. The value of the guest-stats-polling-interval property should survive migration but it can't be done on the QEMU side due to technical limitations.

libvirt has code to set the property on QEMU startup (qemuProcessSetupBalloon) but it doesn't seem to be sending it over to the destination as part of VM migration. Please correct me if I'm wrong.
Comment 2 Peter Krempa 2016-09-05 16:49:30 UTC 
The statistics period is always formatted in the XML (if set):

http://libvirt.org/git/?p=libvirt.git;a=blob;f=src/conf/domain_conf.c;h=c8c4f61cda69dbae2338324a6d5ae95a04050784;hb=HEAD#l21625

and qemuProcessLaunch() which in turn unconditionally calls qemuProcessSetupBalloon() is called on migrations as well.

I've also tried it and libvirt set the 'guest-stats-polling-interval' property and qemu reported success in setting it.

Looking at the history it seems that this was present since we initially added the support for this feature.
Comment 3 Ladi Prosek 2016-09-06 06:28:12 UTC 
Excellent! I stand corrected then, feel free to close the bug.
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