[Pw_forum] QE 6.0 slower than 5.4 ??

[Paolo Giannozzi]

I do not think anything has been done that negatively affects speed of
execution. Before taking seriously any claim on increased or decreased
speed due to X, I want to see a "diff" of two runs made with different X
and all other conditions unchanged; plus a few different runs of the same
code yielding the same results and very close timings.

Paolo

On Wed, Nov 23, 2016 at 12:09 PM, Francesco Pelizza <
francesco.pelizza at strath.ac.uk> wrote:

> Hi Dear community,
>
>
> I have a question...Since the qe 6.0 release i started to use it, and I
> noticed a slow down for systems up to 48 atoms / 100 electrons running
> on few cores, and a speed up running upon more cores.
>
> I other words, taking as example an insulator polymer, set in its
> lattice with 96 electrons:
>
> using qe 5.4 on 8 threads takes 25-35% less time than qe 6.0
>
> that's generally true from scf, to vc-relax to bands and phonon or
> whatever calculations
>
> if I scale on servers or HPC I do not see slow down, and perhaps the qe
> 6.0 is in the average 10-15% faster.
>
>
> Was it expected to be so?
>
> Something changed in the way the system is fragmented across threads?
>
>
> BW
>
> Francesco Pelizza
>
> Strathclyde University
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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