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/...): [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