[Pw_forum] PARA_PREFIX AND PARA_IMAGE_POSTFIX

[Paolo Giannozzi]

On Fri, 2014-01-17 at 13:26 +0000, Elliot Menkah wrote:

> I'm working with a cluster with a total of 128 cores 
> and I want to run a job(relax calculation) with pw.x using 64 cores.
> 
> I'm a bit baffled with the number of processors to set for 
> PARA_IMAGE_PREFIX

PARA_IMAGE_PREFIX is used by examples that run the phonon code
using the "image" parallelization. If all you need is to run
the self-consistent code, you do not need it.

P.

>  since it should be a product of
> number of processors in PARA_PREFIX and the number of images in 
> PARA_IMAGE_POSTFIX.
> 
> When i set -np of PARA_PREFIX to be 64 what should the ideal -np be for 
> PARA_POSTFIX?
> 
> 64x64 = 4096
> 
> the total cores are 128, so 4096 exceeds it.
> 
> Any help or explanation on that is appreciated.
> 
> Thank you.
> 
> Regards,
> 
> Elliot
> 

-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222