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Subject: Re: [hwloc-users] Distances
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2010-05-25 15:21:13


On 25/05/2010 21:02, Wheeler, Kyle Bruce wrote:
> Hello,
>
> I don't see anything in hwloc for determining "distance" between objects in the hierarchy. Is there something I'm missing?
>
> Obviously, distance doesn't make sense between all object types, and begs the question "what units?". However, it's something that is supported in some sense on several systems (liblgrp/libnuma/tmc), and it'd be nice to know it exists in hwloc.
>

Distances is something planned for 1.1. Ticket
https://svn.open-mpi.org/trac/hwloc/ticket/32 is about it. hwloc already
gathers distances from Linux sysfs (from the ACPI SLIT table) and
Solaris to group NUMA nodes accordingly. We need to sort the matrix in
the logical order (instead of OS order) and expose it to the
application. And we need to clarify what we want to support exactly
(extend the NUMA distance to a distance between other objects? what if
we ever get some incomplete distance matrix?). What units must be well
documented too, right.

If you have comments/ideas to add on the ticket, let us know (or get an
account and comment there :)).

Brice