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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 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 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.

Hmm, I heard that some server could run CPUs at different speed.
May be this patch can simulate this behavior. 

Thanks,
Gui


> 
> Regards
> Nikunj
> 
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