[Wien] FFTW and ifx/icx issue relevant to WIEN2k

Fecher, Gerhard fecher at uni-mainz.de
Wed Sep 10 08:45:12 CEST 2025 

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
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