[Pw_forum] QE 6.0 slower than 5.4 ??

[nicola varini]

Hi Francesco, in order to have performance reproducibility be sure to:
-disable hyperthreading
-disable node health check mechanism
In both cases I experienced a slowdown up to a factor 2.
You also mention that you see slowdown while using threads.
The system you mention looks way to small to experience any significant
benefit from MPI+OpenMP execution.

BR,


Nicola


On 11/23/2016 12:09 PM, Francesco Pelizza 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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-- 
Nicola Varini, PhD

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Nicola Varini