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



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.

> "vcpupin" is to define the cpu affinities of vcpus, it will
> not be displayed if one doesn't specify it explicitly in
> XML or set the cpu affinites for vcpu via "vcpupin", means
> there will be no vcpupin element in domain XML by default,
> and the constraints are:

  Okay that semantic is clear

> 
>   - Error if one specify entries more than the count of maxvcpus.
>   - Error when one specify entries for same vcpu.
>   - Error if value of attribute "vcpu" is more than count of
>     "maxvcpus - 1".
>   
>   Attribute "cpuset" works same as "cpuset" of element "vcpu",
> reuse the codes for parsing and formating value of "cpuset"
> of element "vcpu".
> 
> NB, the idea to add persistent XML for "cpushares" is from
> "Nikunj A. Dadhania":
> https://www.redhat.com/archives/libvir-list/2011-January/msg01183.html
> 
> I rebased it and include it together in this patch series.
> 
> [PATCH 1/8] cputune: Add xml schema for cputune xml
> [PATCH 2/8] cputune: Add document for cputune xml
> [PATCH 3/8] cputune: Add data structures presenting cputune xml
> [PATCH 4/8] cputune: implementations of parsing and formating cputune xml
> [PATCH 5/8] cputune: support cputune for qemu driver
> [PATCH 6/8] cputune: support cputune for lxc driver
> [PATCH 7/8] cputune: support cputune for xend driver
> [PATCH 8/8] cputune: new tests for testing cputune xml
> 
> --
> libvir-list mailing list
> libvir-list redhat com
> https://www.redhat.com/mailman/listinfo/libvir-list

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
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http://veillard.com/ | virtualization library  http://libvirt.org/


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