[Wien] some comments on parallel execution of wien2k

[Laurence Marks]

This is a real bug, and the current belief is that using for the
second condition
       iatm_proc_pack=0

is OK -- the main author of the mpi aspects is on holiday (the last I
heard). Oddly enough this bug does not matter with mpich, mvapich,
sgimpi, no idea why.

N.B., I will warn you that openmpi is "difficult" in my opinion. If
you are using an ssh/rsh launcher and have ulimit -s unlimited (or
setenv limit unlimited) as well as LD_LIBRARY_PATH setup correctly in
your .bashrc/.cshrc files you should be OK, otherwise you may be in
trouble. By default openmpi does not export environmental parameters
or the soft kernel stacksize limit which can cause many problems.

On Tue, Jan 5, 2010 at 12:45 PM, Andres Saul <andsaul at gmail.com> wrote:
> Dear wien users:
>   I can also confirm that there is a problem with lapw2_mpi and
> openmpi for some specific combinations of
> the number of atoms and number of processors. The same calculations
> with mpich or hpmpi work fine.
>   Looking at the source files I concluded that the problem was
> related to using a negative second argument
> in MPI_COMM_SPLIT in line 327 of l2main.F (wien2k v9.1).
>
>   I have found that a simple dirty solution consisting in changing
> line 319 from
>         iatm_proc_pack=-(nat+npe+jatom_pe)
> to
>         iatm_proc_pack=10000-(nat+npe+jatom_pe)
>   was enough to solve the problem. I my opinion the occurrence of the
> error for a given number of atoms or specific number of processors is
> related to the "if then else" structure around this line.
>
> Regards
> Andres Saul
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>



-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.