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Subject: Re: [hwloc-devel] structure assumptions, duplication
From: Fawzi Mohamed (fawzi_at_[hidden])
Date: 2009-09-30 03:16:36

On 29-set-09, at 18:55, Fawzi Mohamed wrote:

>>> ok, I was thinking that maybe you did/would like to provide in the
>>> future something akin to what opensolaris does with locality groups
>> Yes, we intend to provide something similar.
>>> In fact what I "need" (or at least I think I need ;) is just the
>>> next
>>> neighbors, basically I go up the hierarchy, and look which new
>>> neighbors I have, so some hierarchy like the lgroups is close to
>>> what
>>> I need, and simpler to handle than the full graph.
>> That's what future heuristics would build for you, yes.
> tha's great, I am really looking forward to it.

So as summary, if I have understood correctly the current idea for the
(future) structure of hwloc is:

1) a fully hierarchical representation of the machine/hardware where
each level is a partition, and each level fully covers the previous
one (from any node you go through all levels using father/childrens,
father/child are just one level away from each other.
This is basically what is there now.

2) outside the hierarchy 1 (but built using its object, probably the
NUMA nodes) there will be
2.1) maybe the full connection graph
2.2) a hierarchical view of it, like the lgroups, where the levels are
not necessarily a partition, and that could also refer not to the
sublevel, but directly to lower levels. Going up the hierarchy you get
the next neighbors.

Separating 1 & 2 has the advantage that stronger assumption can be
done on 1, simplifying it.