5:32 p.m.
Hi
I tried to restrict usage of some running VM by cpu.shares (i.e. set to
10 from original 1024) on loaded system and it seem doesn't work as I
expected... all running processes has same CPU usage (by htop) :-/
Does anyone has same experience?
Fedora 19, libvirt-1.0.5.9-1.fc19.x86_64
Thanks a lot
Martin
--
Martin Pavlásek <mpavlase(a)redhat.com>
OpenStack QA Associate/Red Hat Czech/BRQ
irc: mpavlase
5:42 p.m.
On 03/05/2014 04:32 PM, Martin Pavlásek wrote:
Hi
I tried to restrict usage of some running VM by cpu.shares (i.e. set to
10 from original 1024) on loaded system and it seem doesn't work as I
expected... all running processes has same CPU usage (by htop) :-/
How exactly are you changing the cgroup settings? Are you trying to
directly modify cgroup files (unsupported), or using the libvirt API
(such as via virsh schedinfo)?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
5:47 p.m.
On Thu 06 Mar 2014 00:42:27 CET, Eric Blake wrote:
On 03/05/2014 04:32 PM, Martin Pavlásek wrote:
> Hi
>
> I tried to restrict usage of some running VM by cpu.shares (i.e. set to
> 10 from original 1024) on loaded system and it seem doesn't work as I
> expected... all running processes has same CPU usage (by htop) :-/
How exactly are you changing the cgroup settings? Are you trying to
directly modify cgroup files (unsupported), or using the libvirt API
(such as via virsh schedinfo)?
Via mounted virtualfs -
/sys/fs/cgroup/cpu/machine/<name-of-VM>/{emulator,vcpu0}/cpu.shares
--
--
Martin Pavlásek <mpavlase(a)redhat.com>
OpenStack QA Associate/Red Hat Czech/BRQ
irc: mpavlase
5:51 p.m.
On 03/05/2014 04:47 PM, Martin Pavlásek wrote:
On Thu 06 Mar 2014 00:42:27 CET, Eric Blake wrote:
> On 03/05/2014 04:32 PM, Martin Pavlásek wrote:
>> Hi
>>
>> I tried to restrict usage of some running VM by cpu.shares (i.e. set to
>> 10 from original 1024) on loaded system and it seem doesn't work as I
>> expected... all running processes has same CPU usage (by htop) :-/
>
> How exactly are you changing the cgroup settings? Are you trying to
> directly modify cgroup files (unsupported), or using the libvirt API
> (such as via virsh schedinfo)?
>
Via mounted virtualfs -
/sys/fs/cgroup/cpu/machine/<name-of-VM>/{emulator,vcpu0}/cpu.shares
Won't work, because it goes behind libvirt's back. Use virsh instead.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
11:48 p.m.
Hi Eric,
Sorry to hijack this thread.
Have you used vcpu_quota in production? I have come across a CPU stall
problem when vcpu_quota is effective not long ago and I'm still looking for
an answer.
For example, when I set
virsh schedinfo <id> --set vcpu_quota=5000
Then no matter the vm is loaded or idle, in about two weeks, sometimes
sooner, the vm will have CPU stall in dmesg log. The CPU stall problem
makes system not responsible and results in network failure, i.e. ping and
ssh will fail. I have tried a few guest distro (ubuntu, CentOS, debian)
with different kernel version (3.2, 3.8) and they all have this problem.
Do you have any idea what's behind the scenes?
The software I am running:
hypervisor os: ubuntu 12.04.3
hypervisor kernel: 3.8.0-35-generic
vm os: ubuntu 12.04 // I have tried other OSes.
vm kernel: 3.2.0-56-virtual
libvirt: 1.1.1-0ubuntu8~cloud2
*YY Inc. is hiring openstack and python developers. Interested? Check
http://www.nsbeta.info/jobs <http://www.nsbeta.info/jobs>*
--
Thanks,
Yuanle
On Thu, Mar 6, 2014 at 7:42 AM, Eric Blake <eblake(a)redhat.com> wrote:
On 03/05/2014 04:32 PM, Martin Pavlásek wrote:
> Hi
>
> I tried to restrict usage of some running VM by cpu.shares (i.e. set to
> 10 from original 1024) on loaded system and it seem doesn't work as I
> expected... all running processes has same CPU usage (by htop) :-/
How exactly are you changing the cgroup settings? Are you trying to
directly modify cgroup files (unsupported), or using the libvirt API
(such as via virsh schedinfo)?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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libvirt-users mailing list
libvirt-users(a)redhat.com
https://www.redhat.com/mailman/listinfo/libvirt-users
3:35 a.m.
On Thu, Mar 06, 2014 at 12:32:28AM +0100, Martin Pavlásek wrote:
Hi
I tried to restrict usage of some running VM by cpu.shares (i.e. set to
10 from original 1024) on loaded system and it seem doesn't work as I
expected... all running processes has same CPU usage (by htop) :-/
Does anyone has same experience?
The cpu.shares variable doesn't provide absolute restriction on
CPU usage, rather it is doing relative prioritization.
eg if you have 2 cgroups that are at the same level in the hierarchy
and you give one shares=512 and one shared=1024, then the latter VM
will get twice the CPU scheduler time of the former. If the latter
VM is completely idle though, the former VM will not be capped in any
way.
If you want absolute caps then you need to use period/quota settings.
Also you want todo this via the virsh schedinfo command, not accessing
cgroups directly.
Regards,
Daniel
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