The ABINIT Users Mailing List ( CLOSED )

[Marcel Mohr <marcel@physik.tu-berlin.de>]

On Mon, 11 Feb 2008, Nico Mittenzwey wrote:

> pratik_8mar@yahoo.com wrote:
> > we are buying computer system(Intel xeon processor based workstation) for 
> > ab initio calculations. so which will work better ? multicore(dual core / 
> > quad core) or single core processor?
> > my system will be of  about 30 atoms - optical properties using TDDFT .
>
> The more cores you have the faster abinit ( in the case of a multicore you 
> should use abinip ) will run.

That is in principle true, but cores on the same mainboard share the same resources, 
most important memory bandwidth.

You can nicely see this here in the first example:
http://quasiamore.mit.edu/pmwiki/index.php?n=Main.CP90Timings
where the speedup from 2 to 4 cores is 1.25, and not 2 as expected.

Cheers Marcel