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Subject: Re: [OMPI devel] Speedup for MPI_Dims_create()
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2013-12-19 12:26:01


Andreas --

Thanks for the patch. Can I ask two things?

1. Can you separate the patch into two: one with the code change, and another with the whitespace update? It will help the readability of the logs to see the exact code change, rather than bury it in a syntax update.

2. You added a copyright notice, which is great. However, it puts this patch in a strange position for us -- I think we'd be comfortable with a copyrighted patch if we have a 3rd party agreement on file from your organization (i.e., so that the copyright holder won't come back to us later and sue us for distributing the patch under the BSD license). I think there are two options here (and IANAL, so I could well be wrong here):

2a. Re-submit the patch without a copyright header. It's such a small patch (1 line of code change, AFAICT?) that I think we can accept it without a contribution agreement. We'd cite you in the NEWS file and commit logs, of course.
2b. Submit a third party contribution agreement (see http://www.open-mpi.org/community/contribute/). Then we can list your organization under http://www.open-mpi.org/about/members/, and we can accept the patch with the copyright header.

Thanks!

On Dec 19, 2013, at 9:37 AM, Andreas Schäfer <gentryx_at_[hidden]> wrote:

> Dear all,
>
> please find attached a (trivial) patch to MPI_Dims_create(). When
> computing the prime factors of nnodes, it is sufficient to check for
> primes less or equal to sqrt(nnodes).
>
> This was not so much of a problem in the past, but now that Tier 0
> systems are capable of running O(10^6) MPI processes, the difference
> in execution time is on the order of seconds (e.g. 8.86s vs. 0.04s on
> my notebook, with nnproc = 10^6).
>
> Best
> -Andreas
>
> PS: oh, and the patch removes some trailing whitespace. Yuck. :-)
>
>
> --
> ==========================================================
> Andreas Schäfer
> HPC and Grid Computing
> Chair of Computer Science 3
> Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
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-- 
Jeff Squyres
jsquyres_at_[hidden]
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