On 05/11/2012 03:51 PM, Antonio Carlos Salzvedel Furtado Junior wrote:
Thanks for the prompt response, it cleared a lot of my doubts
Actually, I could enable the other controllers. It's just that I have a strong reason to use the cpu controller. I need to set a hard limit for CPU consumption. Maybe 'cpu.shares' was a bad example. I'm working especially with two parameters, "cpu.cfs_period_us" and "cpu.cfs_quota_us". For instance, sometimes I need to limit my VM to 20% of the CPU share, regardless of the CPU load. Then I set "cpu.cfs_period_us=100000" and "cpu.cfs_quota_us=20000". I'm using the libcgroup API to do that, but I agree that it would be better to use the libvirt API.
Looking at the documentation, The parameters I'd need to change would be the following:
<domain> ... <cputune> <period>100000</period> <quota>20000</quota> </cputune> ... </domain>
Unfortunately, I think virsh does not have tools to change these parameters, as libcgroup does ( cgget and cgset ). However I guess it won't be a problem, I'll try to use the libvirt API.
virsh exposes the libvirt API; if you can't get it working in virsh, that's a bug that we should fix. That said: virsh schedinfo $dom --set vcpu_period=100000 --set vcpu_quota=20000 should do exactly what you're asking for. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org