[QE-developers] DFTI and OpenMP detection in configure

[Ye Luo]

Hi Lorenzo,
I think it is related to your software environment.
I checked today on my machine.
./configure --enable-openmp --with-scalapack=intel
./configure --enable-openmp
I always only get -D__DFTI and no -D__FFTW

Note that -D__FFTW is for internal library.
if you see -D_FFTW, it usually means the configure script not being able to
find an optimized FFT library on your system.
The internal FFTW library is considered less performant compared to vendor
optimized versions.

QE using DFTI works very well with OpenMP. I had study last year.
https://gitlab.com/ye-luo/q-e/wikis/Threading%20the%20parallel%203d%20fft

Best,
Ye
===================
Ye Luo, Ph.D.
Computational Science Division & Leadership Computing Facility
Argonne National Laboratory


Lorenzo Paulatto <paulatz at gmail.com> 于2019年9月16日周一 上午3:31写道：

> Hello,
> I have noticed that the configure script detects and enables
> automatically the DFTI FFT libraries when executed without any specific
> switch, but that it uses FFTW instead when executed with the
> --enable-openmp switch.
>
> I was wondering if this is intentional (i.e. because FFTW can give
> better performance with openmp? Or DFTI does not work with openmp?) or
> it is a bug.
>
> cheers
>
> --
> Dr. Lorenzo Paulatto
> IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université
> phone: +33 (0)1 442 79822 / skype: paulatz
> <http://www.impmc.upmc.fr/~paulatto/> <http://sf.net/p/d3q>
> 23-24/423 B115, 4 place Jussieu 75252 Paris CX 05
>
> --
> Lorenzo Paulatto - Paris
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