I recently tried it. Intels fft in the mkl is even a bit faster than
fftw3 and it works fine in the sequential code, probably except 3ddens !
But because there is no mpi-fftw with Intel, one needs to have the fftw3
anyway.
The intel fftw (cdftlib) is maybe an alternative for a stand-alone
PC/laptop compilation (if you don't need 3ddens).
Am 10.09.2025 um 14:28 schrieb Laurence Marks:
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 <http://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 <[email protected]
<mailto:[email protected]>> 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 <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 <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 [[email protected] <mailto:wien-
[email protected]>] im Auftrag von Laurence Marks
[[email protected] <mailto:[email protected]>]
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 <[email protected]
<mailto:[email protected]><mailto:[email protected]
<mailto:[email protected]>>> 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/ <http://straus.tulane.edu/>
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--
Emeritus Professor Laurence Marks (Laurie)
Northwestern University
Webpage<http://www.numis.northwestern.edu <http://
www.numis.northwestern.edu>> and Google Scholar link<http://
scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en <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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