[Wien] omp vs mpi for LAPW1

[Peter Blaha]

> For omp, I noticed that the calculation takes the 12 threads,

Of course. But this does NOT mean that it runs 12 times faster then with 
one thread. Test the speed (wall time) for 1,2,4,8,12 cores and look at 
your speedup.

> I compiled wien2k with intel cluster (2018) (ifort mpiifort+mkl)
> The option file is in attachment


Do you see 12 lapw1_mpi jobs running simultaneously with nearly 100$ cpu 
in a "top" command ??

What are the actual run times (and you NMAT size)

> 
> Le jeu. 27 août 2020 à 13:11, Peter Blaha <pblaha at theochem.tuwien.ac.at 
> <mailto:pblaha at theochem.tuwien.ac.at>> a écrit :
> 
>     Clearly, omp_global:12   is NOT efficient for lapw1. The
>     diagonalization
>     does not scale for so many cores.
> 
>     Otherwise it means that your mpi-installation (what are you using ?
>     ifort, gfortran, which mpi, blas, scalapack, elpa, ...) is VERY bad.
> 
> 
>     On 8/27/20 1:44 PM, karima Physique wrote:
>      > Dear Wien2k users,
>      >
>      > A calculation with 38 equivalent atoms (96 inequivalent   ), we
>     found
>      > that using lapw1 with omp_global is very faster than lapw1_mpi
>      > machine file 1
>      > omp_global: 12
>      > 1: node1
>      > machine file 2
>      > 1: node1:12
>      > Have you any comment on this?
>      >
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>     -- 
> 
>                                             P.Blaha
>     --------------------------------------------------------------------------
>     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>     Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
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-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
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