[libvirt] [PATCH 0/3] numatune: Prefer old approach

Daniel P. Berrange berrange at redhat.com
Fri Feb 13 14:32:00 UTC 2015


On Thu, Feb 12, 2015 at 06:03:50PM +0100, Michal Privoznik wrote:
> Consider the following part of domain XML:
> 
>   <numatune>
>    <memory mode='static' nodeset="0,2"/>
>   </numatune>
>   <cpu>
>     <numa>
>       <cell id='0' cpus='0' memory='65536' unit='KiB'/>
>     </numa>
>   </cpu>
> 
> Yes, this have a great potential of breaking things. Especially,
> this will break migration between previous two or three upstream
> releases and current release we are working on, because libvirt
> started domains in more complicated way (even if not needed).
> After these patches, domains will be started in simpler way which
> is incompatible.
> 
> On the other hand, we get backward compatibility with much more
> releases than we are about to break.

So with this patch we get guaranteed migration compat for any
configs which were valid under old libvirt. The new syntax
will only ever be used if it is absolutely required, in which
case migration wouldn't be supportable regardless.

It is a shame we didn't think of doing tihs before, but I think
I agree this is the right thing todo now. We're doomed either
way, but this way feels like it minimises the doom to a smaller
set of people.

Regards,
Daniel
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