[Nek5000-users] Does Nek5000 use any kind of parallelism inside one element?

[nek5000-users at lists.mcs.anl.gov]

Dear Nek5000 developpers and users,

my name is Lars Haupt and I'am writing my phd-thesis at the moment, which has something to do with scalable p-multigrid based approaches. Therefore i have to understand the state of the art multigrid solver Nek5000 and thats why i'am trying to get some insides into Nek5000 parallelism.

I read the article about the scalability of the Nek5000 Code which was achieved on the Juelich Supercomputer in 2010.
I thought that the impressive strong scaling speedup was a result of an optimised hybrid parallelization strategy (MPI and OpenMP).

But the general info on the Nek5000 website says that only MPI does the parallel job. Which means, domain decomposition is the only kind of parallelism?
What happens with the huge amount of nodes inside one element? The FAQ tells something about high efficient matrix-matrix multiplications. Which are implemented using MKL-BLAS 3 dgemm routines, i guess?
If that is the case, does Nek5000 use any OpenMP based parallelism inside MKL or why not?

Many thanks in advance

Lars Haupt

Dipl.-Math. Lars Haupt
Wissenschaftlicher Mitarbeiter

Technische Universität Dresden
Fakultät Maschinenwesen
Institut für Energietechnik
Professur für Gebäudeenergietechnik und Wärmeversorgung
01062 Dresden
Tel.: +49(351) 463-37619
Fax.: +49(351) 463-37076
E-Mail: lars.haupt at tu-dresden.de





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