Re: [Xen-devel] _PXM, NUMA, and all that goodnesss

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.02.14 at 12:21, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 13/02/14 10:08, Jan Beulich wrote:
>>>  2) Would it be better to just look at making the initial domain
>>>    be able to figure out the NUMA topology and assign the
>>>    correct 'numa_node' in the PCI fields?
>> As said above, I don't think this should be exposed to and
>> handled in Dom0's kernel. It's the tool stack to have the overall
>> view here.
> 
> This is where things get awkward.  Dom0 has the real APCI tables and is
> the only entity with the ability to evaluate the _PXM() attributes to
> work out which PCI devices belong to which NUMA nodes.  On the other
> hand, its idea of cpus and numa is stifled by being virtual and
> generally not having access to all the cpus it can see as present in the
> ACPI tables.
> 
> It would certainly be nice for dom0 to report the _PXM() attributes back
> up to Xen, but I have no idea how easy/hard it would be.

But that's being done already (see Konrad's original post), just
that the hypervisor doesn't really make use of the information
at present.

Jan


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