[Pw_forum] Parallel PWSCF

[Giovanni Cantele]

Hashem Al-Yamani wrote:
> Dear All ;
>  
> Is it neccessary that jobs be faster while using parallel environment 
> thatn in serial ?
It is not! It depends on the code, how many CPUs are used, their 
interconnection....

Of course, if you properly use parallelism, it can significantly improve 
the performances
of a given code and Quantum-Espresso is quite a good example!!!!   :-)
>  
> and if not so what is the use of parallel environment ??
If your question concerns parallel computing in general, you can search, 
for example "parallel programming" on google.
Among the results, from: http://en.wikipedia.org/wiki/Parallel_computing

*Parallel computing* is the simultaneous execution of the /same task/ 
(split up and specially adapted) on multiple processors 
<http://en.wikipedia.org/wiki/Central_processing_unit> in order to 
obtain results faster. The idea is based on the fact that the process of 
solving a problem usually can be divided into smaller tasks, which may 
be carried out simultaneously with some coordination.

Lot of manuals and handbooks, including examples, can also be found.


Instead, if you question concerns, more specifically parallelism 
performances in Quantum-Espresso, you could start from
answers already given in this forum, that you can easily browse using 
the Search option.
For example:
http://www.democritos.it/pipermail/pw_forum/2005-September/002993.html


Also, you could have a look to the user guide:

http://www.quantum-espresso.org/wiki/index.php/User_Guide

Here, you'll find a section "Performance issues (PWscf) 
<http://www.quantum-espresso.org/wiki/index.php/Performance_issues_%28PWscf%29>" 
that could give answers to your questions.


Hope this helps,
Giovanni


-- 



Dr. Giovanni Cantele
Coherentia CNR-INFM and Dipartimento di Scienze Fisiche
Universita' di Napoli "Federico II"
Complesso Universitario di Monte S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
Phone: +39 081 676910
Fax:   +39 081 676346
E-mail: Giovanni.Cantele at na.infn.it
Web: http://people.na.infn.it/~cantele