[Q-e-developers] Compiling QE-GPU without openmp

[Filippo SPIGA]

Hello Pietro,

I do not have access to a Cray system at the moment and I do not recall last time I tried to compile QE on a Cray by myself. I am sure Intel and GNU are supported for the current public QE-GPU. PGI should work as well. On a machine with many different compilers (most of the recent Cray deployments have compilers from several vendors), Cray it is probably my last choice (together with NAG).

I dig into Cray ftn wrapper documentation using google so ... what I am going to say it may not work, someone need to test it for me!

When Cray compilers are used, OpenMP is enabled by default. If you specify "--disable-openmp" the configure does not take any action to disable the default behaviour of the compiler. The situation that occurs is the following: there is not "-D__OPENMP" in LDFLAGS (because of  "--disable-openmp" flag in the configure) _but_ the compiler recornises anyway the OpenMP directives. An error occurs because a variable is missing in fact if you look at the source code of PW/newq_compute_gpu.f90 in QE-GPU you will notice that the declaration of that variable is protected by a ifdef macro.

What you can try to do is to add "-h noomp" to F90FLAGS, FFLAGS and CFLAGS. "make -f Makefile.gpu clean" and "make -f Makefile.gpu pw-gpu" again. It may work.

Second (easy) option: you can compile with OpenMP but keep OMP_NUM_THREADS=1 and the behaviour is more or less the same when "--disable-openmp" is used.

HTH

On Jul 15, 2016, at 2:36 PM, Pietro Bonfa' <pietro.bonfa at fis.unipr.it> wrote:
> 
> Dear Filippo,
> 
> I'm sorry, I saw that there is a misleading information in the
> compile.sh file on github.
> 
> The error shows up if I use PrgEnv-cray module (module switch
> PrgEnv-intel PrgEnv-cray).
> 
> I put the output of "ftn --cray-print-opts" and "ftn -craype-verbose"
> here: http://pastie.org/10908149
> 
> Bests,
> Pietro

--
Mr. Filippo SPIGA, M.Sc.
Quantum ESPRESSO Foundation
http://www.quantum-espresso.org

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