Re: [Xen-devel] RFC: Still TODO for 4.2? xl domain numa memory allocation vs xm/xend

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Fri, 2012-01-20 at 16:55 +0000, Ian Campbell wrote:
> On Fri, 2012-01-20 at 16:43 +0000, George Dunlap wrote:
> > On Fri, 2012-01-20 at 16:39 +0000, Ian Campbell wrote:
> > > On Fri, 2012-01-20 at 16:31 +0000, George Dunlap wrote:
> > > > On Fri, 2012-01-20 at 16:28 +0000, Ian Campbell wrote:
> > > > > On Fri, 2012-01-20 at 16:21 +0000, Ian Campbell wrote:
> > > > > > cpupools don't seem to do this, I don't know if that is expected or 
> > > > > > not.
> > > > > 
> > > > > Right, so cpupools do not appear to set the vcpu affinity, at least 
> > > > > not
> > > > > at the level where it effects memory allocation. However both
> > > > >       pool="Pool-node0" cpus="0-7"
> > > > > and
> > > > >       pool="Pool-node1" cpus="8-15"
> > > > > work as expected on a system with 8 cpus per node.
> > > > > 
> > > > > Should something be doing this pinning automatically?
> > > > 
> > > > It seems like it would be useful; But then we have the issue of, if a vm
> > > > was pinned to cpus 0-3 of Pool-node0, and you move it to Pool-node1,
> > > > what do you do?
> > > 
> > > I've no idea, it's not clear to me now what the semantics of cpupools
> > > are if they don't restrict the VCPU affinity like I previously assumed.
> > 
> > Well, it does restrict what cpus the VM will run on; the effective
> > affinity will be the union of the pool cpus and the vcpu affinity.
> 
> Did you mean intersection?

Hmm, seems it's been too long since I used set theory. :-)  Yes,
intersection; (i.e., a vcpu will run on a cpu only if the cpu is in the
affinity mask and the cpu pool).

 -George


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