Re: Off topic: Numactl "distance" wrong

[Cliff Wickman <cpw@sgi.com>]

On Fri, Apr 03, 2009 at 01:49:27PM -0700, Yinghai Lu wrote:
> On Fri, Apr 3, 2009 at 1:16 PM, Brice Goglin <Brice.Goglin@inria.fr> wrote:
> > Chris Worley wrote:
> >> Sorry for an off topic, but I'm hoping somebody can point me in the
> >> right direction of where to direct this question...
> >>
> >> I have an Opteron system where I've seen the HW diagrams, and each of
> >> 4 sockets is directly connected (HT) to two other sockets, and two HT
> >> hops away from a third (i.e. a simple square topology, no X in the
> >> middle).
> >>
> >> Yet, "numactl --hardware" shows but one hop to each socket:
> >>
> >> # numactl --hardware
> >> ...
> >> node   0   1   2   3
> >>   0:  10  20  20  20
> >>   1:  20  10  20  20
> >>   2:  20  20  10  20
> >>   3:  20  20  20  10
> >>
> >> I know this is wrong.
> >>
> >> Who would be the right person (or list) to talk about this?

numactl and libnuma are discussed on
linux-numa@vger.kernel.org

> >>
> >
> > IIRC, the motherboard/BIOS is supposed to report numa distances through
> > the PXM ACPI method. But I have never seen any opteron box do it
> > properly. So you just get 10 for "local" and 20 for "remote". Some
> > Itanium machines however report actual distances.
> 
> for x86 64 bit, we are copying SLIT table and save another copy.
> 
> could provide one /sys interface to make user could modify it...
> 
> YH
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-- 
Cliff Wickman
Silicon Graphics, Inc.
cpw@sgi.com
(651) 683-3824