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Subject: Re: [OMPI devel] RFC: Remove (broken) heterogeneous support
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2013-01-30 09:46:45

On Jan 30, 2013, at 9:40 AM, Andreas Schäfer <gentryx_at_[hidden]> wrote:

> But isn't heterogeneity the main reason for having MPI datatypes in
> the first place? Otherwise I could always use MPI_CHAR and sizeof(Foo).

Heterogeneity was a much bigger issue back in the 90s. Nowadays, most people have pretty homogeneous clusters.

>> Understood. But the reality is that this is a very uncommon feature, and we apparently don't have the resources to fix it. :-\
> Could you give a rough estimate on how much effort this would be?

Unfortunately, no. No one has even looked into this.

I'm *guessing* that it's not a difficult issue to fix -- that something is just broken down in the datatype handling of heterogeneous machines. But that's an assumption/guess. Tracking that down, however, will likely take a little effort, especially for someone unfamiliar with the code base. I can give hints where to start looking, but that's about it.

Jeff Squyres
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