From mboxrd@z Thu Jan  1 00:00:00 1970
From: zimoun <zimon.toutoune@gmail.com>
Subject: Re: Guix-HPC activity report
Date: Fri, 22 Feb 2019 16:41:23 +0100
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To: =?UTF-8?Q?Ludovic_Court=C3=A8s?= <ludovic.courtes@inria.fr>
Cc: guix-devel <guix-devel@gnu.org>

Hi Ludo,

Thank you for your precision.

On Fri, 15 Feb 2019 at 18:09, Ludovic Court=C3=A8s <ludovic.courtes@inria.f=
r> wrote:
>
> zimoun <zimon.toutoune@gmail.com> skribis:
>
> > Well, is it still accurate ?
> > Is Guix binary still slower than other ?
>
> The comment links to
> <http://fftw.org/fftw3_doc/Installation-on-Unix.html>, which reads:
>
>   Enable various SIMD instruction sets. [=E2=80=A6] FFTW will try to dete=
ct at
>   runtime whether the CPU supports these extensions.  That is, you can
>   compile with --enable-avx and the code will still run on a CPU without
>   AVX support.

If I understand well, the claims p.45 of the EasyBuild presentation
[1] should not true any more.
Because there is a factor 2+ with their benchmarks.

[1] https://users.ugent.be/~kehoste/eum18/eum18_easybuild_past_present_futu=
re_20180130.pdf


> So I believe the numbers one gets with the =E2=80=98fftw=E2=80=99 package=
 in Guix are
> the best one can get because FFTW does the right thing of using the
> right version of its hot functions at run time.  (That said, you can
> redo the benchs, and if this is not the case, it=E2=80=99s a bug! :-))

A benchmark from "our side" should be informative. :-)
But I am not sure that I would like to dive in EasyBuild stuff... ;-)


Thank you again !
All the best,
simon