On 06/01/2013 06:49 PM, Dennis Chen wrote:
On 06/01/2013 03:16 PM, Dennis Chen wrote:
On 05/29/2013 04:28 AM, Eric Blake wrote:
On 05/28/2013 02:24 PM, Eric Blake wrote:
So the question is: is there any method I can't find yet to change
the
vcpu count of a running vm dynamically?
Wait for newer qemu and libvirt, or else pitch in and help write
patches.
You might not have to wait that long - if you could help test these
patches, it would be appreciated:
https://www.redhat.com/archives/libvir-list/2013-May/msg01857.html
Hi,
After apply the patch, I've made a test. The testing environment as:
virsh # version
Compiled against library: libvirt 1.0.5
Using library: libvirt 1.0.5
Using API: QEMU 1.0.5
Running hypervisor: QEMU 1.5.0
The xml piece of the vm domain:
<channel type='unix'>
<source mode='bind'
path='/var/lib/libvirt/qemu/f16x86_64.agent'/>
<target type='virtio' name='org.qemu.guest_agent.0'/>
</channel>
the network connection between the vm and host is ok.
Also I installed the qemu-guest-agent in the guest os:
[root@localhost ~]#rpm -qa | grep qemu-guest
qemu-guest-agent-0.12.1.2-2.355.el6.i686
An error happened when I try to offline a guest vcpu in virsh:
virsh # setguestvcpu 8 1 --offline
error: Guest agent is not responding: Guest agent not available for now
Is there some step I missed before I invoke the 'setguestvcpu'
command in virsh or I need to write a program to hot-plug/unplug the
vcpu with the help of the new API introduced by this patch? Thanks!
BRs,
Dennis
update after investigation, I need to start up the 'qemu-guest-agent'
daemon in the guest
(https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/qemu-ga.html):
[root@localhost ~]#qemu-ga
After that, I tried the command again:
virsh # setguestvcpu 8 1 --offline
error: internal error unable to execute QEMU agent command
'guest-set-vcpus': The command guest-set-vcpus has not been found
I think the communication between monitor and guest is ok, because
below command is OK:
virsh # shutdown 8 --mode agent
Domain 8 is being shutdown
VM shutdown after this command. Also, I double checked the
src/qemu/qemu_agent.c, and I can find the 2 functions:
qemuAgentGetVCPUs() and qemuAgentSetVCPUs()
Another,
virsh # qemu-agent-command 9 '{"execute":"cpu-add","arguments":{"id":2}}'
{"error":{"class":"CommandNotFound","desc":"The command cpu-add has
not been found","data":{"name":"cpu-add"}}}
Seems the guest agent can't find vcpu hot-plug/unplug command, the
qemu I am using is 1.5.0, does it need some patches to handle this or
something I still missed?
hmm, I forget to upgrade the qemu-ga in guest os from 1.0 to 1.5.0. So I
did that, the latest update --
The internal error doesn't show for "setguestvcpu 10 1 --offline" cmd,
it's ok to offline the logic cpu id 1 when I checked it within the
guest. But seems the output of "vcpuinfo/vcpucount" is not changed
accordingly, e.g:
virsh # vcpuinfo 10
VCPU: 0
CPU: 1
State: running
..
VCPU: 1
CPU: 3
State: running
...
both are running (actually the vcpu 1 is offline). plus,
virsh # vcpumap 10 --offline --agent
CPU map: -y
but
virsh # vcpumap 10 --offline
CPU map: --
Last, in the qmp-commands.txt of qemu-1.5.0 and also mentioned in the
patch [8/11]:
"This patch implements support for the "cpu-add" QMP command that plugs
CPUs into a live guest. The "cpu-add" command was introduced in QEMU
1.5"
but in my environment,
virsh # qemu-agent-command 10 '{"execute":"cpu-add","arguments":{"id":2}}'
{"error":{"class":"CommandNotFound","desc":"The command cpu-add has not
been found"}}
is "cpu-add" supported by qemu 1.5.0 now? or something I still missed?
IMO, the "cpu-add" is used to hot-plug a vcpu into the guest, so if the
vcpu count specified in a vm xml is, e.g., 4, I can hotplug a new vcpu
(totally 5 then) into the guest during runtime, is that correct?
BRs,
Dennis
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