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

[Lorenzo Paulatto]

Hi,
I did not follow the discussion, 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 
>> <mailto: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 <mailto:q-e-developers at qe-forge.org>>
>> *To: *spiga.filippo at gmail.com <mailto: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
>
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> Mr. Filippo SPIGA, M.Sc.
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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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