Bug 799180 - Sometimes guest become not to respond when change vcpu
Summary: Sometimes guest become not to respond when change vcpu
Keywords:
Status: CLOSED DUPLICATE of bug 788562
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.2
Hardware: Unspecified
OS: Unspecified
high
medium
Target Milestone: rc
: ---
Assignee: Red Hat Kernel Manager
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-03-02 03:17 UTC by yuping zhang
Modified: 2013-01-10 00:45 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2012-05-23 21:31:12 UTC
Target Upstream Version:

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Description yuping zhang 2012-03-02 03:17:24 UTC 
Description of problem:
Perpare a rhel6.2 guest, then change the vcpu,sometimes the guest will become not to respond.

Version-Release number of selected component (if applicable):
qemu-kvm-0.12.1.2-2.234.el6.x86_64
libvirt-0.9.10-3.el6.x86_64
virt-manager-0.9.0-10.el6.x86_64

How reproducible:
90%

Steps to Reproduce:
1.Start a rhel6.2 guest.
#virsh dumpxml rhel6.2-new
...
<currentMemory>1048576</currentMemory>
<vcpu current='2'>4</vcpu>
...
2. Wait for the guest boot completely,then run
#virsh setvcpus rhel6.2-new 1 --live
#virsh setvcpus rhel6.2-new 3 --live
Or
You can use virt-manager to change the Current allocation of CPU,then apply.

3.Check the guest with virt-manager or virt-viewer.

Actual results:
The guest become no respond.

Expected results:
The guest works well and the vcpu will not update.
As we know,the qemu-kvm doesn't support vcpu hotplug now.The libvirt provide the API for it.
But I think the guest should not become not to respond at least.

Additional info:
1. I can reproduce this issue on rhel6 guest 100%,and can not reproduce on rhel5 guest.
2. You can change the vcpus several times if you can not reproduce this issue.
Comment 3 Dave Allan 2012-05-23 20:27:45 UTC 
Based on the fact that the reproduction is completely dependent on the guest OS, I believe this BZ is not a libvirt problem, so I'm reassigning to kernel.  Please correct me if I'm wrong about that.
Comment 4 Igor Mammedov 2012-05-23 21:31:12 UTC 
Closingas duplicate of bug 788562

Please re-test with RHEL6.3 kernel (kernel-2.6.32-235.el6 or later), where issue is fixed or disable kvm-clock in qemu to workaround issue on RHEL6.2.

Dor:
It might be good idea to clone bug 788562 for RHEL6.2 z stream.

*** This bug has been marked as a duplicate of bug 788562 ***
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