[Pw_forum] Off-topic: parallel compilation

[Marcos Veríssimo Alves]

Hi all,

This is a bit off-topic, but I'm sure there will be many knowledgeable
people around. It's related to the parallel compilation of QE.

I'm trying to run HSE calculations for a 71-atom silicene sheet, using
Espresso compiled with ifort (composerxe), mpich2 and intel mkl included in
this version of the compiler. Mpich 2 is compiled using gcc/ifort.

All goes well in the scf part until it gets to the hybrid functional
calculation. Then it crashes with an mpi error (Bad termination, code
9) which the mpi faq says is usually due to the fact that there is a
segmentation fault in the code, not in mpi.  They also state that this is
usually a segmentation fault.

I wonder if anyone has run HSE calculations for systems as large as this,
and if they have run into this problem.

One possibility that came to my mind is that, if this is a segmentation
fault, maybe 4-byte integers are not large enough to address all the
indexes of the arrays allocated in the hybrid functional part of the
calculation. I tried to compile QE with 8-byte integers but I get an mpi
error, which I suppose is due to integers being compiled with 4-byte
integers on the C side of the compilation.

So, I have two questions:

1) Is there any way of compiling Mpich 2 with 8-byte integers using gcc?

2) If the parallel part were carried out with OpenMP instead of Mpich (I
have 32 cores in the same node of the computer I'm running the
calculation), perhaps this could be a workaround for this problem. Is it
possible to compile QE in parallel mode using only OpenMP and MKL? If yes,
what options would need to be set for either configure or make.sys
directly? Configure already detects the mpi environment, and sets make.sys
to compile QE using it.

Any help would be greatly appreciated, and I would gladly supply the input
file along with the pseudo I am using (from the QE database) if the
developers would like to run tests on it.

Best regards,

Marcos
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