[libvirt] [RFC] Add persistent XML for cpu tunables

[Osier Yang]

于 2011年03月29日 16:18, Nikunj A. Dadhania 写道:
> On Tue, 29 Mar 2011 15:31:19 +0800, Daniel Veillard<veillard at redhat.com>  wrote:
>> On Tue, Mar 29, 2011 at 02:32:18PM +0800, Osier Yang wrote:
>>> Example of cputune XML:
>>>    <cputune>
>>>      <shares>2048</shares>
>>>      <vcpupin vcpu='0' cpuset='0-4,^1'/>
>>>      <vcpupin vcpu='1' cpuset='1,3'/>
>>>      <vcpupin vcpu='2' cpuset='0,2'/>
>>>    </cputune>
>>>
>>> "shares" is to define the the proportional weighted cpu share
>>> for the domain.
>>
>>    Hum, what does "2048" there means ? I assume there is an unit but
>> it's not defined. Can we get a precide definition of the semantic of
>> the shares construct. If I were to use it I need to know what it means,
>> and I can't just from that description. Drivers in QEmu and LXC just
>> pass that down to linux, but it still doesn't provide a semantic for
>> it and "whatever linux implements at the time" is not really a good
>> answer.
>>
> The number is relative wrt other domains/cgroup, so if we have two VMs
> each having 2048, both of them will get equal share, i.e. 50% each. In a
> different scenario, if we have VM1's share as 1024 and VM2's share as
> 2048, that translates as VM1=33% and VM2=66% share of the CPU.

V2 posted with idea from Matthias, and borrow some text from virsh doc.

>
> Regards
> Nikunj