Re: Problem of host CPU topology parsing

[Osier Yang <jyang@xxxxxxxxxx>]

On 2012年05月11日 16:40, Osier Yang wrote:
> On 2012年05月11日 16:35, Daniel P. Berrange wrote:
> > On Fri, May 11, 2012 at 04:21:48PM +0800, Osier Yang wrote:
> > > Hi,
> > >
> > > We have problem of host CPU topology parsing on special
> > > platforms (general platforms are fine). E.g.
> > >
> > > On a AMD machine with 48 CPUs [1] (4 sockets, 6 cores indeed
> > > [2]), VIR_NODEINFO_MAXCPUS [3] will always return 24 as the
> > > total CPU number.
> >
> > If it is returning 24, then surely we have the 'nodes' value
> > wrong in the virNodeInfo ? It sounds like it should have been
> > set to 2 (4 * 6 * 2 => 48)
>
> /* nodeinfo->sockets is supposed to be a number of sockets per NUMA node,
> * however if NUMA nodes are not composed of whole sockets, we just lie
> * about the number of NUMA nodes and force apps to check capabilities XML
> * for the actual NUMA topology.
> */
> if (nodeinfo->sockets % nodeinfo->nodes == 0)
> nodeinfo->sockets /= nodeinfo->nodes;
> else
> nodeinfo->nodes = 1;
>
> Jirka said this was for a fix, but I don't quite understand it,
> what does the "nodeinfo.nodes" mean actually? Shouldn't it
> be 8 (for the 48 CPUs machine) instead?But then we will be
> wrong again with using VIR_NODEINFO_MAXCPUS.

The capabilities output:

http://fpaste.org/0SG5/

> > > [3] #define VIR_NODEINFO_MAXCPUS(nodeinfo)
> > > ((nodeinfo).nodes*(nodeinfo).sockets*(nodeinfo).cores*(nodeinfo).threads)
> >
> > Rgeards,
> > Daniel
>
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