[Commits] meeting minutes for 2017-03-06

[Erik Schnetter]

On Mon, Mar 6, 2017 at 10:55 AM, Roland Haas <rhaas at illinois.edu> wrote:

> Hello all,
>
> > We quickly discussed the failing tests, and given that the option list
> > used
> > (https://bitbucket.org/ianhinder/cactusjenkins/raw/
> d7021a52bd83448db589b2346c43441682eecabb/build.cfg)
> > is not using -ffast-math or -mmarch=native the working assumption is
> > that the occurrence of the failures is due to to an updated OS and
> > newer compiler. Erik asked if we had a docker container for the
> > Jenkins test slave, which we were not sure (there is a docker image at
> > https://bitbucket.org/ianhinder/et-jenkins-slave though it is not
> > clear if this is the one used).
>
> after the call of course I realized what may cause differences even
> without -march=native or -ffast-math: the explicit vectorization in
> thorn Vectors depends on the machine architecture so different hardware
> (eg AVX2) will produce different vector code and thus different
> answers. Though given the thorns affected (GRHydro and
> SphericalHarmonicRecon) I doubt that it is the thorn's code itself but
> rather eg McLachlan or the fftw library (for the PITTNull code). This
> *may* cause differences though a different compiler *will* cause
> differences (in particular a different Fortran compiler).


That's a good point.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/
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