[Wien] Installation with MPI and GNU compilers

[Pavel Ondračka]

Rui Costa píše v St 04. 04. 2018 v 14:21 +0100:
> I will see what I can do about the Intel compilers. I've had a
> question about this, supposedly the intel compilers are the fastest
> [https://www.mail-
> archive.com/wien at zeus.theochem.tuwien.ac.at/msg13021.html], but how
> much faster are they than the others? I expect this to vary from case
> to case but on average, how much faster are they?

In fact the compiler (e.g. ifort vs gfortran) hardly makes a difference
. The important part are the algebra libraries. The opensource OpenBLAS
should be almost identical to Intels MKL (see https://www.mail-archive.
com/wien at zeus.theochem.tuwien.ac.at/msg15106.html for comparison of
OenBLAS vs MKL). However in this old benchmark the opensource stack is
still quite slower since the MKL also provides the VML library for
vectorized math functions, which did not had any open source
alternative for a long time. Recently there is the libmvec library
which provides such functions (you need recent glibc), but there is no
official Wien2k support for this. However it is actually quite easy to
get it working (see https://www.mail-archive.com/wien@zeus.theochem.tuw
ien.ac.at/msg16159.html ).
Hence if you use the gfortran + OpenBLAS + libmvec the performance is
virtually identical to ifort + MKL + VML. The setup is somewhat more
difficult though.

Best regards
Pavel

> My objective is not to do simulations with mpi in the computer that
> I'm trying to install but to figure out how to install wien2k with
> mpi and then give some guidelines to the IT technician. I spent two
> weeks telling them that the simulations were not running because the
> packages were not compiled and in the end everything was poorly
> installed.
> 
> Thank you for your help.
> 
> Best regards,
> Rui Costa.
>