[CentOS-virt] Nested KVM issue

Sun Aug 14 18:43:52 UTC 2016
Boris Derzhavets <bderzhavets at hotmail.com>

From: centos-virt-bounces at centos.org <centos-virt-bounces at centos.org> on behalf of Laurentiu Soica <laurentiu at soica.ro>
Sent: Sunday, August 14, 2016 10:17 AM
To: Discussion about the virtualization on CentOS
Subject: Re: [CentOS-virt] Nested KVM issue

More details on the subject:

I suppose it is a nested KVM issue because it raised after I enabled the nested KVM feature. Without it, anyway, the second level VMs are unusable in terms of performance.

I am using CentOS 7 with:

kernel: 3.10.0-327.22.2.el7.x86_64

on both the baremetal and the compute VM.

Please, post

1) # virsh dumpxml  VM-L1  ( where on L1 level you expect nested KVM to appear)
2) Login into VM-L1 and run :-
    # lsmod | grep kvm
3) I need outputs from VM-L1 ( in case it is Compute Node )

# cat /etc/nova/nova.conf | grep virt_type
# cat /etc/nova/nova.conf | grep  cpu_mode


The only workaround now is to shutdown the compute VM and start it back from baremetal with virsh start.
A simple restart of the compute node doesn't help. It looks like the qemu-kvm process corresponding to the compute VM is the problem.


În dum., 14 aug. 2016 la 00:19, Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> a scris:

I have an OpenStack setup in virtual environment on CentOS 7.

The baremetal has nested KVM enabled and 1 compute node as a VM.

Inside the compute node I have multiple VMs running.

After about every 3 days the VMs get inaccessible and the compute node reports high CPU usage. The qemu-kvm process for each VM inside the compute node reports full CPU usage.

Please help me with some hints to debug this issue.

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