2:24 a.m.
Hi,
We know that there is a command "setvcpus" in virsh used to "change
number of virtual CPUs", now we just have the need to change vcpu count
dynamically for a running VM, so I tried this command (the vcpu count is
2 in the VM xml file), below is the result:
virsh # setvcpus 3 --count 4
error: invalid argument: requested vcpus is greater than max allowable
vcpus for the domain: 4 > 2
virsh # setvcpus 3 --count 1
error: Operation not supported: qemu didn't unplug the vCPUs properly
So I tried another way: log into the running VM, and "echo 0 >
/sys/devices/system/cpu/cpu1/online", after that I can find only one
processor in the vm through '/proc/cpuinfo', but in virsh, the vcpuinfo
still shows:
virsh # vcpuinfo 3
VCPU: 0
CPU: 0
State: running
CPU time: 13.5s
CPU Affinity: yyyy
VCPU: 1
CPU: 1
State: running
CPU time: 6.9s
CPU Affinity: yyyy
So the question is: is there any method I can't find yet to change the
vcpu count of a running vm dynamically?
BRs,
Dennis
3:24 p.m.
On 05/28/2013 01:24 AM, Dennis Chen wrote:
Hi,
We know that there is a command "setvcpus" in virsh used to "change
number of virtual CPUs", now we just have the need to change vcpu count
dynamically for a running VM, so I tried this command (the vcpu count is
2 in the VM xml file), below is the result:
virsh # setvcpus 3 --count 4
error: invalid argument: requested vcpus is greater than max allowable
vcpus for the domain: 4 > 2
Correct - you can't exceed the maximum number of vcpus that you told
qemu on its initial command line. Worse, qemu hasn't supported cpu
hotplug or hot-unplug for quite some time (qemu 1.5 added partial
support for hotplug, but still left hot-unplug unimplemented; qemu 1.5
also added support for guest-agent unplug, but we have not yet wired
that up in libvirt).
virsh # setvcpus 3 --count 1
error: Operation not supported: qemu didn't unplug the vCPUs properly
Alas, until qemu actually implements vcpu hot-unplug, this will fail for
you (it works for xen:// URI though).
So I tried another way: log into the running VM, and "echo 0 >
/sys/devices/system/cpu/cpu1/online", after that I can find only one
processor in the vm through '/proc/cpuinfo', but in virsh, the vcpuinfo
still shows:
That's not hot-unplug from qemu's perspective. That's just disabling
the use of the cpu from within the guest (and in fact, that's what the
new qemu 1.5 guest agent commands do, where we are still working on how
best to wire that up into libvirt).
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.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
3:28 p.m.
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
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
7:41 p.m.
OK, thanks Eric! We'll test these patches and give the update then...
BRs,
Dennis
-----Original Message-----
From: Eric Blake [mailto:eblake@redhat.com]
Sent: 2013年5月29日 4:28
Cc: Dennis Chen; libvirt-users(a)redhat.com
Subject: Re: [libvirt-users] About the change of a VM's vcpu count in runtime?
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
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
2:16 a.m.
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
5:49 a.m.
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_Lin...):
[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?
BRs,
Dennis
1:50 a.m.
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_Lin...):
[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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