[Pw_forum] Bugs found when compiling QE 5.1 on BGP

[Paolo Giannozzi]

On Fri, 2014-08-22 at 17:39 -0400, Filipe Camargo Dalmatti Alves Lima
wrote:

> We then manually changed the make.sys file from
> LD             = /bgsys/drivers/ppcfloor/comm/xl.ndebug/bin/mpixlf90_r
> to
> LD             = /bgsys/drivers/ppcfloor/comm/xl/bin/mpixlf90_r

you find in install/README.CINECA_fermi at point 3) the explanation of 
the "ndebug" stuff. Apparently it is not present in your system.

> Next, we encountered issues with some OMP lines in the files:
> Modules/tsvdw.f90 
> and
> Modules/mm_dispersion.f90

The compilers on BG machines yield very frequently OpenMP-related
errors, sometimes for no obvious reasons. The BG/Q in CINECA (Bologna)
does not yield such errors.

> The errors all relate to the REDUCTION clause of omp lines. [...]
> To eliminate these errors, we disabled omp at those lines by deleting
> the omp commands.  However, we would prefer to use the full capacity
> of omp, and we are unsure if we may accidentally interfere other
> aspects of the code by removing this.

if you just disable OpenMP in those two parts, there will be:
- no effect at all, if you do not use Van der Waals corrections
- a hard-to-quantify but presumably small loss in performance,
  if you do

P.
> 
> Regards,
> 
> 
> Filipe and Paul Whitford
> 
> 
> -- 
> _________________________________________
> Filipe Camargo Dalmatti Alves Lima
> PhD Student
> University of São Paulo, Physics Institute, Materials Physics
> Department, Nanomol Group, Brazil.
> Phones:    (11) 3091-6881  (USP)
>                 (11) 97408-2755 (Vivo)
> 
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222