[DFTB-Plus-User] performance on ryzen cpus

[Karol Strutynski]

--
Karol Strutyński
CICECO - Aveiro Institute of Materials
Department of Chemistry
University of Aveiro
Office 29.3.25
3810-193, Aveiro, PORTUGAL
Phone: +48 739259476
Mail: strutynski.karol at gmail.com, skarol at ua.pt
ORCID: http://orcid.org/0000-0001-8733-9012

On Wed, 12 Dec 2018 at 18:54, Ben Hourahine
<benjamin.hourahine at strath.ac.uk> wrote:
>
> There are reports that OpenBLAS is faster than MKL on AMD, for example:
>
> https://discourse.julialang.org/t/openblas-is-faster-than-intel-mkl-on-amd-hardware-ryzen/8033

My test with OpenBLAS provided strange results.
It is worse than intel cpu, but sometimes slightly better than
ifort+mkl on ryzen cpu for the systems I checked (up to 1500 atoms).
The worrying part is that gcc+OpenBLAS is less predictable - using
more cores is sometimes slower. This was not the case in other
compilations, and I choose test systems large enough to have and
effect.

Overall for the time being ifort+mkl seem to be the way to go, at
least safer because of consistency with number of processes used.

It might be something unrelated to DFTB+, I tested another tight
binding program and it was also slower on EPYC machine.

>
> On 12/12/18 18:40, Karol Strutynski wrote:
> > Hello,
> >
> > Best Regards,
> > --
> > Karol Strutyński
> > CICECO - Aveiro Institute of Materials
> > Department of Chemistry
> > University of Aveiro
> > Office 29.3.25
> > 3810-193, Aveiro, PORTUGAL
> > Phone: +48 739259476
> > Mail: strutynski.karol at gmail.com, skarol at ua.pt
> > ORCID: http://orcid.org/0000-0001-8733-9012
> >
> > On Wed, 12 Dec 2018 at 18:18, Ben Hourahine
> > <benjamin.hourahine at strath.ac.uk> wrote:
> >> Hello Karol,
> >>
> >> what are you using for BLAS operations? Reasonable size ground state
> >> calculations use >95% of the cpu time inside LAPACK/BLAS.
> > I tested several options, and intel MKL with ifort result in best performance.
> >
> >> Regards
> >>
> >> Ben
> >>
> >> On 12/12/18 17:53, Karol Strutynski wrote:
> >>> Hello,
> >>> My group have a machines with ryzen EPYC processors. I noticed that
> >>> the performance of DFTB+ (version 18.2) is much worse than on
> >>> equivalent intel cpu.
> >>> I tried various compilers (gcc , ifort, aocc flang) with variation of flags.
> >>> The best I got was using intel 2018 compiler with "-O3 -qopenmp -ip
> >>> -standard-semantics -heap-arrays 10 -axAVX  -xHost -fast" flags.
> >>> The results are usually the same - intel cpu is much faster than EPYC,
> >>> in extreme cases the times are almost three times larger.
> >>>
> >>> The other programs compiled on the ryzen present performance similar
> >>> to intel machine.
> >>>
> >>> It is quite possible I missed something during optimization. Does
> >>> anybody have experience with running dftb+ on amd based machines?
> >>>
> >>> Best Regards,
> >>> --
> >>> Karol Strutyński
> >>> CICECO - Aveiro Institute of Materials
> >>> Department of Chemistry
> >>> University of Aveiro
> >>> Office 29.3.25
> >>> 3810-193, Aveiro, PORTUGAL
> >>> Phone: +48 739259476
> >>> Mail: strutynski.karol at gmail.com, skarol at ua.pt
> >>> ORCID: http://orcid.org/0000-0001-8733-9012
> >>> _______________________________________________
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> >> --
> >>       Dr. B. Hourahine, SUPA, Department of Physics,
> >>     University of Strathclyde, John Anderson Building,
> >>             107 Rottenrow, Glasgow G4 0NG, UK.
> >>     +44 141 548 2325, benjamin.hourahine at strath.ac.uk
> >>
> >> 2013/4 THE Awards Entrepreneurial University of the Year
> >>       2012/13 THE Awards UK University of the Year
> >>
> >>    The University of Strathclyde is a charitable body,
> >>         registered in Scotland, number SC015263
> >>
> >> _______________________________________________
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>
> --
>       Dr. B. Hourahine, SUPA, Department of Physics,
>     University of Strathclyde, John Anderson Building,
>             107 Rottenrow, Glasgow G4 0NG, UK.
>     +44 141 548 2325, benjamin.hourahine at strath.ac.uk
>
> 2013/4 THE Awards Entrepreneurial University of the Year
>       2012/13 THE Awards UK University of the Year
>
>    The University of Strathclyde is a charitable body,
>         registered in Scotland, number SC015263
>
> _______________________________________________
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