Re: [libvirt] [PATCH 5/6] qemu: Implement hypervisor's period and quota tunable XML configuration and parsing

At 05/17/2012 01:42 PM, Hu Tao Wrote: > On Thu, May 17, 2012 at 01:25:48PM +0800, Wen Congyang wrote: >> At 05/17/2012 01:09 PM, KAMEZAWA Hiroyuki Wrote: >>> (2012/05/17 14:07), Wen Congyang wrote: >>> >>>> At 05/17/2012 12:46 PM, KAMEZAWA Hiroyuki Wrote: >>>>> (2012/05/17 12:54), Wen Congyang wrote: >>> >>>>>> So, if we donot limit the hypervisor, the behavior shoule not be >>>>>> changed. So we should limit the whole vm. If the hypervisor threads >>>>>> are limited, there is no need to limit the whole vm. >>>>>> >>>>> >>>>> >>>>> need to tune hypervisor quota to limit vcpu-only quota ? >>>>> Sounds strange to me. >>>> >>>> No, current implemetion is: >>>> 1. limit vcpu and hypervisor: vm is not limited >>>> 2. limit vcpu only: vm is limited >>>> 3. limit hypervisor: vm is not limited >>>> 4. vcpu and hypervisor are not limited: vm is not limited. >>>> >>> >>> >>> In 2. >>> >>> vm ----- quota_is_limited >>> |- hypervisor ----- quota is unlimited >>> |- vcpu[0...x] ----- quota is limited >>> >>> Hm...vm is limited. It seems user need to tune vm's quota...can user >>> makes vm's quota to be unlimited and limit *only* vpcus as Xen ? >> >> Without this patchset, the vm will be limited if the vcpu is limited. >> We cannot know whether the hypervisor is unlimited or the user does not >> set it. If the user does not set it, we should not change the behavior. >> So I donot find an easy way to limit only vcpus. > > Can we change the implementation like these: > > 1. > <cputune> > <vcpu> > <period>period</period> > <quota>quota</quota> > </vcpu> > </cputune> > > Limit vcpus only, does not limit vm or hypervisor. > > 2. > <cputune> > <hypervisor> > <period>period</period> > <quota>quota</quota> > </hypervisor> > </cputune> > > Limit hypervisor only, does not limit vm or vcpus. > > 3. > <cputune> > <period>period</period> > <quota>quota</quota> > </cputune> > > Limit the whole vm, in this case vcpus and hypervisor are also limited. > > 4. > <cputune> > <period>period</period> > <quota>quota</quota> > <vcpu> > <period>period</period> > <quota>quota</quota> > </vcpu> > <hypervisor> > <period>period</period> > <quota>quota</quota> > </hypervisor> > </cputune> This is very complex, and the user should know how we implement it and the period/quota's limit. If the user gives a wrong value, the vm cannot start. We implement the limit like this: vm | ---------------------------- | ... | | vcpu0 vcpun hypervisor If all is limited, the vm's quota should be greater than max(vcpu's quota, hypervisor's quota) and vm's period should be less than min(vcpu's period, hypervisor's period). So I donot like this idea.