[Wien] FFTW and ifx/icx issue relevant to WIEN2k
Laurence Marks
laurence.marks at gmail.com
Wed Sep 10 14:28:28 CEST 2025
Just to clarify one statement I made: linking against both your own fftw &
Intel's is very dangerous. It may be that some subroutines will come from
your library, some from Intel's and there is no reason they should be
compatible. Only use one of the two.
N.B., I am not certain that the Intel fftw is compatible with W2k. I tried
some years ago and decided I was wasting time on non-critical code, so only
use fftw3. If someone is using cdft please post here.
___
Emeritus Professor Laurence Marks (Laurie)
Department of Materials Science and Engineering, Northwestern University
www.numis.northwestern.edu
"Research is to see what everybody else has seen, and to think what nobody
else has thought" Albert Szent-Györgyi
On Wed, Sep 10, 2025, 01:51 Fecher, Gerhard <fecher at uni-mainz.de> wrote:
> more comments
> I could not find that zenver5 is a valid CPU architecture for ixc or ifx
> on
> https://www.intel.com/content/www/us/en/docs/fortran-compiler/developer-guide-reference/2025-2/march.html
> (this concerns also other CPU dependent compiler switches -x, -ax, -arch,
> there is no zenverX)
> It seems it was just used by a "beginner" hoshi on
> https://community.intel.com/t5/Intel-Fortran-Compiler/Compilation-error-with-fast-on-AMD-Ryzen-9-9900X-using-ifx/td-p/1712241
> I would guess -march=znver5 (because it can be used with the GNU
> compilers) is just ignored why should Intel be interested to write an
> optimized comnpiler for AMD CPU's ?
> Did you ever test whether -march=znver5 changes anything ?
> As mentioned earlier -axCORE-AVX512, -axCORE-AVX2 or a combination of both
> may work on AMD processors (at least they don't slow the programm
> seriuously, and I didn't find dead electrons)
>
> There was already a lot of discussion on FFTW3 and ELPA at the beginning
> of the year
>
> Ciao
> Gerhard
>
> DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
> "I think the problem, to be quite honest with you,
> is that you have never actually known what the question is."
>
> ====================================
> Dr. Gerhard H. Fecher
> Institut of Physics
> Johannes Gutenberg - University
> 55099 Mainz
> ________________________________________
> Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von
> Laurence Marks [laurence.marks at gmail.com]
> Gesendet: Dienstag, 9. September 2025 23:20
> An: A Mailing list for WIEN2k users
> Betreff: Re: [Wien] FFTW and ifx/icx issue relevant to WIEN2k
>
> Comments.
>
> 1. I have never seen -O3 do anything with icc/ifort except kill
> defenceless electrons and make the code slower. I will be happy to be
> proved wrong with ifx/icx.
> 2. I always use -mkl, rather than making mistakes chasing how intel
> changes its libraries.
> 3. I think you might have issues with -mkl_cdft (intel's version of
> fftw) and FFTW3
>
> On Tue, Sep 9, 2025 at 4:10 PM Straus, Daniel B <dstraus at tulane.edu
> <mailto:dstraus at tulane.edu>> wrote:
> Sorry for the long delay in responding—I was set to receive a digest of
> list messages, and it only comes once every couple of weeks.
>
> Yes, this is on a Zen 5 computer, and it is running Rocky Linux 10. I am
> using the Intel compiler and MKL, rather than the one AMD provides. IFX and
> ICX support the march=znver5 flag. All the WIEN2k 24.1 patches available as
> of 9/1 were installed.
>
> To be clear, on my workstation, FFTW still will work with WIEN2k even if
> the autoconf script is not regenerated, but there may be a performance
> impact as it is not using the proper Intel libraries for Fortran calls to
> FFTW. However, 3ddens would then not compile, and if I also attempted to
> use ELPA, then parallel LAPW1 would not compile. Regenerating the autoconf
> script for FFTW and recompiling it solved both problems. You should check
> the config.log for your FFTW compilation to see if there is a line such as
> “ld: cannot find -loopopt=0” to see if this error is occurring. For me, the
> configure script continued even after this error, but it was using GNU
> default libraries rather than the Intel provided libraries.
>
> siteconfig_lapw is set to use the ifx and icx compilers, and here are the
> flags under “Options” in siteconfig_lapw I am using the following compiler
> options for WIEN2k with the IFX compiler.
> Current settings:
> M OpenMP switch: -qopenmp
> O Compiler options: -O3 -march=znver5 -traceback -assume
> buffered_io -FR -I$(MKLROOT)/include
> L Linker Flags: $(FOPT) -L$(MKLROOT)/lib -lpthread -lm -ldl
> -liomp5 -Wl,-rpath,$MKLROOT/lib
> P Preprocessor flags '-DParallel'
> R R_LIBS (LAPACK+BLAS): -lmkl_intel_lp64 -lmkl_intel_thread
> -lmkl_core
> F FFTW options: -DFFTW3 -DFFTW_OMP
> -I/home/software/fftw-3.3.10/include
> FFTW-LIBS: -L/home/software/fftw-3.3.10/lib -lfftw3
> -lfftw3_omp
> X LIBX options:
> LIBXC-LIBS:
>
> For Parallel Options in siteconfig_lapw, here are the flags I am using:
> Your current parallel settings (options and libraries) are:
> C Parallel Compiler: mpiifx
> FP Parallel Compiler Options: -O3 -FR -march=znver5 -fc=ifx
> -traceback -assume buffered_io -I$(MKLROOT)/include
> MP MPIRUN command: mpirun -np _NP_ -machinefile _HOSTS_
> _EXEC_
> O Parallel OpenMP switch: -qopenmp
> Additional setting for SLURM batch systems (is set to 1 otherwise):
> CN Number of Cores: 1
> Libraries:
> Sp SCALAPACK: -L$(MKLROOT)/lib
> -lmkl_scalapack_lp64
> -L$(MKLROOT)/lib
> -lmkl_blacs_intelmpi_lp64
> E ELPA options: -DELPA
> -I/home/software/elpa-2025.06.001/include/elpa-2025.06.001/elpa
>
> -I/home/software/elpa-2025.06.001/include/elpa-2025.06.001/modules
> ELPA-LIBS: -lelpa
> -L/home/software/elpa-2025.06.001/lib
> -Wl,-rpath=/home/software/elpa-2025.06.001/lib
> RP Parallel-Libs: $(R_LIBS) -lmkl_cdft_core
>
> In case it’s relevant here is what I passed to the configure script for
> FFTW3 (after regenerating the script with autoconf):
> module load oneapi/2025.2.0
> ./configure --prefix=/home/software/fftw-3.3.10 CC="mpiicx -cc=icx"
> MPICC="mpiicx -cc=icx" F77="mpiifx -fc=ifx" FFLAGS="-O3 -march=znver5
> -I"${MKLROOT}/include"" CFLAGS="-O3 -march=znver5 -I"${MKLROOT}/include""
> CXXFLAGS="-I"${MKLROOT}/include"" LDFLAGS="-L${MKLROOT}/lib
> -lmkl_scalapack_lp64 -lmkl_cdft_core -lmkl_intel_lp64 -lmkl_intel_thread
> -lmkl_core -lmkl_blacs_intelmpi_lp64 -liomp5 -lpthread -lm -ldl"
> --enable-option-checking=fatal --enable-avx512 --enable-avx2 --enable-mpi
> --enable-openmp --enable-threads
>
> And for ELPA:
> module load oneapi/2025.2.0
> ./configure --prefix=/home/software/elpa-2025.06.001 CC="mpiicx -cc=icx"
> CXX="mpiicpx -cxx=icpx" FC="mpiifx -fc=ifx" CFLAGS="-O3 -march=znver5
> -I"${MKLROOT}/include"" FCFLAGS="-O3 -march=znver5 -I"${MKLROOT}/include""
> CXXFLAGS="-O3 -march=znver5 -I"${MKLROOT}/include""
> LDFLAGS="-L${MKLROOT}/lib -lmkl_scalapack_lp64 -lmkl_cdft_core
> -lmkl_intel_lp64 -lmkl_intel_thread -lmkl_core -lmkl_blacs_intelmpi_lp64
> -liomp5 -lpthread -lm -ldl" --enable-option-checking=fatal --with-mpi=yes
> --enable-openmp=yes
>
> Hopefully this is helpful.
>
>
>
> Daniel Straus
> Assistant Professor
> Department of Chemistry
> Tulane University
> 5088 Percival Stern Hall
> 6400 Freret Street
> New Orleans, LA 70118
> (504) 862-3585
> http://straus.tulane.edu/
>
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>
> --
> Emeritus Professor Laurence Marks (Laurie)
> Northwestern University
> Webpage<http://www.numis.northwestern.edu> and Google Scholar link<
> http://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en>
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought", Albert Szent-Györgyi
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