[QE-users] Sub optimal performance on 32 core AMD machine

[Paolo Giannozzi]

On Tue, Nov 17, 2020 at 9:20 PM Pamela Whitfield <whitfieldps1 at gmail.com>
wrote:

Hyperthreading is necessary for the GPU version which works fine for DFTD2
> but not for DFTD3 - hence I use a CPU-only MPI-only version for the more
> complex dispersion corrections.
>

If I remember correctly, there is no parallelization at all in DFT-D3
(while DFT-D2 is parallelized with both MPI and OpenMP)

Paolo


> My problems are probably very similar to Michal, a 2500 cubic Angstrom
> cell is not that unusual so my runs are often measured in hours/days and
> not minutes. I don't think any sane person is going to buy a Quadro GV100
> to save a few seconds!
>
> I'll now shut up and go away into my experimentalist corner....
>
> Best regards
> Pam Whitfield
>
> Hello Pamela,
> I don't know whether it is clear or not, so I apologize if I repeat obvious
> concepts.
> I just bought a Threadripper 3990X with 64 core 128 threads. As far as I
> remember the 3960X should have 24 core - 48 threads.
> It is very very important to don't use more than 24 cores on 3960X . Simply
> forget about hyperthreading. No need to disable it in the BIOS, but simply
> count the real number of cores.
>
> I use gcc 9.3.0 and the new gcc 10 should be even better for AMD cpus.
> With openblas 0.3.12 I found that my 8-cores home Ryzen 3800X is fast as a
> Xeon 12 cores E5-2680 using quantum espresso 6.4.1
> Carlo
>
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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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