On 07/17/2012 05:16 PM, Eric Blake wrote:
On 07/17/2012 04:50 PM, Orion Poplawski wrote:
> While staring at top on my SL6 kvm server waiting for it to crash, I
> noticed that my idle Fedora kvm guests appear to be consuming between
> 8-12% cpu while my idle SL6 guests appear to be consuming between 0.3-2%
> cpu as shown in the qemu-kvm processes in top. In fact I have a Fedora
> 17 instance running now with nothing but kernel processes and the
> qemu-kvm process still shows it using 7-8% cpu.
>
> Does anyone have any insight as to why this would be the case?
Could it be an issue of vnc vs. spice? It may help if you provide the
'virsh dumpxml $dom' of the two guests in question, to point out if any
difference in configuration may be responsible. Also bear in mind that
the virt stack strives for guest ABI compatibility - so a guest created
2 years ago will still use the defaults from 2 years ago, even if the
defaults have since improved in the meantime for a guest created today.
You can rewrite the XML, generally with no ill effects to a Linux
guest, but at risk of having to revalidate a Windows guest (hence why
the virt stack strives for stable ABI instead of auto-rewriting your
guests to use latest-and-greatest defaults).
Using VNC for all. There is very little difference in the configuration. For
one example (drupal is SL6, mock1 is Fedora 17):
diff drupal.xml mock1.xml
1,6c1,6
< <domain type='kvm' id='1'>
< <name>drupal</name>
< <uuid>bfdc6b27-396d-83d7-0c91-8e610aa3a40d</uuid>
< <memory unit='KiB'>524288</memory>
< <currentMemory unit='KiB'>524288</currentMemory>
< <vcpu placement='static'>1</vcpu>
---
<domain type='kvm' id='6'>
<name>mock1</name>
<uuid>bf102e31-36c5-d9bf-9000-29293e927fef</uuid>
<memory unit='KiB'>2097152</memory>
<currentMemory unit='KiB'>2097152</currentMemory>
<vcpu placement='static'>4</vcpu>
8c8
< <type arch='x86_64' machine='rhel6.2.0'>hvm</type>
---
<type arch='x86_64'
machine='rhel6.1.0'>hvm</type>
24c24
< <source dev='/dev/vg_root/vm_drupal'/>
---
<source dev='/dev/vg_root/vm_mock1'/>
34c34
< <mac address='40:00:00:00:00:10'/>
---
<mac address='40:00:00:00:00:11'/>
36c36
< <target dev='vnet0'/>
---
<target dev='vnet2'/>
42c42
< <source path='/dev/pts/1'/>
---
<source path='/dev/pts/8'/>
46,47c46,47
< <console type='pty' tty='/dev/pts/1'>
< <source path='/dev/pts/1'/>
---
> <console type='pty' tty='/dev/pts/8'>
<source path='/dev/pts/8'/>
55c55
< <graphics type='vnc' port='5900' autoport='yes'
keymap='en-us'/>
---
<graphics type='vnc' port='5902'
autoport='yes' keymap='en-us'/>
67,68c67,68
< <label>system_u:system_r:svirt_t:s0:c288,c830</label>
<
<imagelabel>system_u:object_r:svirt_image_t:s0:c288,c830</imagelabel>
---
<label>system_u:system_r:svirt_t:s0:c129,c713</label>
<imagelabel>system_u:object_r:svirt_image_t:s0:c129,c713</imagelabel>
All my other domains are "rhel6.1.0" and the SL6 one is fine.
At this point I would have to think it is differences in the guest kernels.
Not sure what the best way of tracing what the qmeu-kvm process is doing and
comparing them.
--
Orion Poplawski
Technical Manager 303-415-9701 x222
NWRA, Boulder Office FAX: 303-415-9702
3380 Mitchell Lane orion(a)nwra.com
Boulder, CO 80301
http://www.nwra.com