Re: [libvirt] [PATCH 06/10] vcpubandwidth: introduce two new libvirt APIs

On 2011-7-5 16:41, Nikunj A. Dadhania wrote: > On Tue, 05 Jul 2011 15:06:06 +0800, Wen Congyang <wency(a)cn.fujitsu.com&gt; wrote: >> At 07/04/2011 07:19 PM, Nikunj A. Dadhania Write: >>> On Thu, 30 Jun 2011 11:13:18 +0800, Wen Congyang <wency(a)cn.fujitsu.com&gt; wrote: >>>> We want to control bandwidth for each vcpu, so we can not use the >>>> API virDomainSetSchedulerParameters(). Introduce two new APIs to >>>> change and query bandwidth for each vcpu. >>>> >>> Will we have different cpu bandwidth for different vcpus? >>> >>> Something like this: >>> >>> vcpu1: 1000000/250000 >>> vcpu2: 1000000/500000 >>> vcpu3: 1000000/300000 >>> vcpu4: 1000000/400000 >>> >>> IMO, that is not required, we can have a top level bandwitdh for the VM >>> and then redistribute it among vcpus equally, without user knowing about >>> it. >>> >>> Something like this: >>> >>> VM1(4vcpu) has to be throttled at 1CPU bandwidth using SetSchedParamters. >>> >>> Internally libvirt splits it equally: >>> vcpu1: 1000000/250000 >>> vcpu2: 1000000/250000 >>> vcpu3: 1000000/250000 >>> vcpu4: 1000000/250000 >>> >>> So why introduce VCPU level apis? >> >> Adam Litke said IBM's performance team nead to control cpu bandwidth for each >> vcpu. > Right, but we do not export that as a User API, that was my suggestion. > We can internally control each vcpu's bandwidth, i.e. divide equally. Hmm, I heard that some server could run CPUs at different speed. May be this patch can simulate this behavior.