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

At 05/17/2012 02:06 PM, KAMEZAWA Hiroyuki Wrote: > (2012/05/17 15:05), Wen Congyang wrote: > >> 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. >> > > > Hmm. my proposal is not so complicated as you say. And simpler than your way. > > <quota target='all|vcpu'> </quota> # all is default and limit the whole vm. > # vcpu is just limit vcpus rather than whole vm. > <period> .... </period> # period is shared in all settings. > > Isn't it ? Do you mean this: <cputune> <vcpu> <period>period</period> <quota target='all|vcpu'>quota</quota> </vcpu> <hypervisor> <period>period</period> <quota>quota</quota> </hypervisor> </cputune>