Bug 1371581

Summary:	Preserve the guest-stats-polling-interval property across migrations
Product:	Red Hat Enterprise Linux 7	Reporter:	Ladi Prosek <lprosek>
Component:	libvirt	Assignee:	Jiri Denemark <jdenemar>
Status:	CLOSED NOTABUG	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.4	CC:	pkrempa, rbalakri
Target Milestone:	rc
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Last Closed:	2016-09-06 12:12:06 UTC	Type:	Bug
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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.