[gmx-users] Detection for best SIMD instructions failed, using SIMD None

[Mark Abraham]

Hi,

I would have expected that to work without issue, but that cmake is pretty
new. What is the output of the resulting gmx -version? That runs the same
code. Also the content of the CMakeCache.txt in the build directory would
help us see if something is amiss and fixable.

Mark

On Thu., 4 Apr. 2019, 22:00 Jochen Hub, <jhub at gwdg.de> wrote:

> Hi developers,
>
> cmake is not able to detect that our CPUs support AVX2_256:
>
> -- Detecting best SIMD instructions for this CPU
> -- Detection for best SIMD instructions failed, using SIMD - None
>
> This happens on
>
> - Arch Linux
> - Gromacs 2018.6 and 2019.1
> - cmake version 3.14.1
> - with Intel Xeon E5-2643 v4 and Xeon E-2136
> - gcc 8.2.1
>
> When specifying manually
>
> cmake -DGMX_SIMD=AVX2_256
>
> all is fine and mdrun runs smoothly with expected performance.
>
> Is this the intended behavior? Is there something we should report to
> find the reason for this behavior?
>
> Thank you,
> Jochen
>
> --
> ---------------------------------------------------
> Dr. Jochen Hub
> Computational Molecular Biophysics Group
> Institute for Microbiology and Genetics
> Georg-August-University of Göttingen
> Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
> Phone: +49-551-39-14189
> http://cmb.bio.uni-goettingen.de/
> ---------------------------------------------------
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