[Wien] Multicore on i7 iMac

[Peter Blaha]

As you could see from your "top" command, only 1 core is used.

The "simplest" thing is to set:

export OMP_NUM_THREADS=2 (or 4)    (a commented line is already in your 
.bashrc after  "userconfig_lapw")

This will use 2 (4) cores for parts of WIEN2k which uses the mkl-library.
---------------------------
Next is k-parallel mode   (see UG for description), where you can use 
all your cores.

We also have mpi-parallel, but I would not recommend it for a single 
mac, unless you have a problem with just one k-point.

Please also notice the recent posting on the mailing-list about a 
recommended compiler option for a Mac (-heap-arrays), otherwise you 
cannot run wien2k on larger systems

Peter Blaha



From:pluto at physics.ucdavis.edu
Date:04/14/2013 07:48 PM
To:"A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>

Hello WIEN2k experts,

I have a very simple question.

Do I need to edit the .machines file for the multicore operation of the
Intel i7 Quad Core CPU?

My IT department (in FZ Juelich, Germany) has helped to compile Wien2k on
an iMac with i7 CPU. It works very nice, no problem to calculate 15 layer
slab. However, I have a feeling, that all is done on a single core, and
this is a real waste to time. I attach the screenshot of "top" program
under the terminal, with lapw1c doing 100 k-points for band structure.

Regards,
Lukasz