> Well, this is interesting. numactl --hardware shows the number of
> hops, regarding to the information from that private BZ.

I think this is wrong. numactl takes everything from sysfs as far as I
can tell. On x86, sysfs distances are ACPI SLIT latencies (memory
latencies that are normalized to 10 for latencies from one cpu to its
local memory). A couple months ago, I checked all Linux ports that show
distances in sysfs. All of them report memory latencies, except the SGI
IP27 as mentioned previously (this one indeed shows number of hops (0
when local) and it makes a lot of sense for this architecture).

Yes, you are absolutly right. Sorry about it. It's better to check some sources than to rely on my own memory:-)

One problem I see with the number of hops is that it doesn't make sense
on some machines. On some 8-socket AMD machines (such as
8amd64-4n2c.tar.bz2 below) , the hypertransport route between some
sockets varies with the type of packet (response or request) and the
direction. So the number of hops ends up being asymmetric, depends on
read/write, and can be half of an integer.

Yes, this is exactly what I have seen as well. This even true for 4 socket AMD Magny Cours system.

Look at tests/linux/ in the hwloc SVN. The following tarballs contain
NUMA architectures. Some of these were gathered while running old
kernels, but I don't think it matters because Linux/sysfs reports what
the BIOS without changing much of it.

I will. The thing is that I'm pretty bu\sy right now, I need to finish a project before going on vacation. I hope to look into in September.

Regards
Jirka