Re: [gmx-developers] warning Emulating FMA instructions - this is probably not what you want!

[Berk Hess]

Hi,

ICC can actually sometimes be (a lot) faster than gcc on AMD.
The issue here seems to be that the configuration didn't add a compiler flag for fma4.

Cheers,

Berk

----- Reply message -----
From: "Alexey Shvetsov" <alexxy at omrb.pnpi.spb.ru>
To: <gmx-developers at gromacs.org>
Subject: [gmx-developers] warning Emulating FMA instructions - this is	probably not what you want!
Date: Wed, Oct 17, 2012 14:00


Hi all!

Well ICC isnt good with AMD CPUs especialy with new ones. Try to use 
recent gcc versions like gcc-4.7.


Jochen Hub писал 17-10-2012 13:14:
> Hi developers,
>
> does anyone know how to interpret this icc warning:
>
> [  8%] /home/jhub/src/gromacs/include/gmx_x86_avx_128_fma.h(88):
> warning #1224: #warning directive: Emulating FMA instructions - this
> is probably not what you want!
>
>   #warning Emulating FMA instructions - this is probably not what you 
> want!
>
> I am compiling 46-release on a Interlagos 6378 with OpenMPI and icc
> 13.0.0 20120731. My cmake line is:
>
> cmake $gmxsrc \
>     -DFFTW_LIBRARY=$FFTW_LOCATION/lib/libfftw3f.a \
>     -DFFTW3F_INCLUDE_DIR=$FFTW_LOCATION/include \
>     -DFFTW3F_LIBRARIES=$FFTW_LOCATION/lib/libfftw3f.a \
>     -DCMAKE_INSTALL_PREFIX=$(pwd) \
>     -DGMX_X11=OFF \
>     -DCMAKE_CXX_COMPILER=$MPICXX \
>     -DCMAKE_C_COMPILER=$MPICC \
>     -DGMX_MPI=ON \
>     -DGMX_PREFER_STATIC_LIBS=ON \
>     -DGMX_GPU=OFF
>
> and cmake reported:
>
> -- Performing Test GNU_AVX_CFLAG
> -- Performing Test GNU_AVX_CFLAG - Success
> -- Enabling 128-bit AVX Gromacs acceleration (with fused-multiply
> add), and it will help compiler optimization.
>
> Thanks a lot,
> 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/
> ---------------------------------------------------

-- 
Best Regards,
Alexey 'Alexxy' Shvetsov
Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, 
Gatchina, Russia
Department of Molecular and Radiation Biophysics
Gentoo Team Ru
Gentoo Linux Dev
mailto:alexxyum at gmail.com
mailto:alexxy at gentoo.org
mailto:alexxy at omrb.pnpi.spb.ru
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