[Q-e-developers] Fwd: vdw-d failing test (./check-pw.x.j)

[Paolo Giannozzi]

On Sat, 2014-11-01 at 22:36 +0100, Lorenzo Paulatto wrote:

> I did not follow the discussion

nor did I, so can somebody please make a summary:
- was the error already present in v. 5.1, or is it new?
- has the place where the error occurs been found?
- if so, is there a workaround?

Paolo
> , but I can confirm that doing openmp operation on function results
> with intel compiler (2013 and 2014, afaik) results in all kind of
> eisenbugs.
> 
> cheers
> 
> 
> 
> On 11/01/2014 01:14 PM, Filippo Spiga wrote:
> 
> > FYI Gabriele's email bounced back, here below his message! 
> > 
> > 
> > F
> > 
> > > Begin forwarded message:
> > > 
> > > From: Gabriele Sclauzero <gurlomail at gmail.com>
> > > 
> > > Subject: Re: [Q-e-developers] vdw-d failing test (./check-pw.x.j)
> > > 
> > > Date: October 31, 2014 at 7:13:37 PM GMT
> > > 
> > > Cc: General discussion list for Quantum ESPRESSO developers
> > > <q-e-developers at qe-forge.org>
> > > 
> > > To: spiga.filippo at gmail.com
> > > 
> > > 
> > > Dear Filippo, 
> > > 
> > > 
> > >     Indeed, that commit was intended to fix a problem of OpenMP
> > > parallelization in the calculation of forces with Grimme’s
> > > dispersion (mm_dispersion.f90 module). The problem shows up with
> > > some Intel compilers, but it doesn’t with the GNU ones (so, it
> > > might be a bug of the Intel compiler, perhaps). If you look inside
> > > vdw-d.out and you find that the output stops just before printing
> > > out the forces, it is likely the same problem that I have met.
> > > The workaround consists in doing the reduction on an auxiliary
> > > array, aux(:), instead of doing it directly on force_london(:,:).
> > > The latter is an array with two dimensions, so I think this
> > > confuses the OpenMP compilation part (for Intel, at least).
> > > Anyway, the fix seems to do the job without sacrificing
> > > performance. 
> > > 
> > > 
> > > Ciao,
> > > 
> > > 
> > > Gabriele
> > 
> > --
> > Mr. Filippo SPIGA, M.Sc.
> > http://filippospiga.info ~ skype: filippo.spiga
> > 
> > «Nobody will drive us out of Cantor's paradise.» ~ David Hilbert
> > 
> > *****
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> > 
> > 
> > 
> > 
> > 
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> -- 
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> +33 (0)1 44 275 084 / skype: paulatz
> http://www-int.impmc.upmc.fr/~paulatto/
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