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Subject: Re: [OMPI users] EXTERNAL: Re: How is hwloc used by OpenMPI
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2012-11-08 11:07:18

On Nov 8, 2012, at 10:17 AM, Blosch, Edwin L wrote:

> Thanks, I definitely appreciate the new, hotness of hwloc. I just couldn't tell from the documentation or the web page how or if it was being used by OpenMPI.
> I still work with OpenMPI 1.4.x and now that I've looked into the builds, I think I understand that PLPA is used in 1.4 and hwloc is brought in as an MCA module in 1.6.x.

Correct. PLPA was a first attempt at a generic processor affinity solution. hwloc is a 2nd generation, much Much MUCH better solution than PLPA (we wholly killed PLPA after the INRIA guys designed hwloc).

> Re: layering, I believe you are saying that the relationship to libnuma is not one where hwloc is adding higher-level functionalities to libnuma, but rather hwloc is a much improved alternative except for a few system calls it makes via libnuma out of necessity or convenience.


Jeff Squyres
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