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

[Nikunj A. Dadhania]

On Tue, 05 Jul 2011 15:06:06 +0800, Wen Congyang <wency at cn.fujitsu.com> wrote:
> At 07/04/2011 07:19 PM, Nikunj A. Dadhania Write:
> > On Thu, 30 Jun 2011 11:13:18 +0800, Wen Congyang <wency at cn.fujitsu.com> 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.

Regards
Nikunj