Subject: Re: CCL:Opteron or Nocona ?

From: mark somers <m.somers*&*chem.leidenuniv.nl>
Date: Mon, 9 May 2005 09:38:06 +0200

Dear Luigi Cavallo,

we have recently purchased and setup a new Beowulf cluster here in Leiden, 
dedicated to run ADF and other DFT codes (Dacapo and Vasp) on it. We have 
found the Nocona's, in combination with the Intel compilers, to be the best 
combination especially for ADF and ADF-BAND.

Before we decided to go for the Nocona's, we did try with two test machines, 
one being a dual-cpu AMD Opteron 246 (2.0 GHz) and the other being a dual-cpu 
Nocona (3.0 GHz). Tests showed that the AMD has, in general, a slightly 
better cache hierarchy and a better memory scalability, but also that the 
lack of compilers able to tune for the Opterons is severe. Of course we took 
the differences in cpu clocks into account.

As it turns out, after having contacted the SCM people in Amsterdam, ADF can 
effectively use the SSE3 registers and cpu intruction set and that makes it 
run fast on the Nocona's. This, together with the prices being roughly the 
same, made us decide to go for the Nocona's. 

BTW, maybe this is known to you already, but Intel offers you their OpenMP 
capable compilers for free for academic use. 

The machine is up and running now in 64 bit mode and doing fine ;-). 

Maybe the information can help you in your decision.

Best regards, 

Mark Somers.

> Hi,
>
> we are going to invest some money for a few computers, and we have to
> make a decision between the AMD-Opterons and the Intel-Nocona. What's
> better ? We are experienced with the Opterons, but we have no idea about
> the Noconas...
>
> Major codes to run on them will be classical QM packages as ADF, G03, TM,
> some AIMD as CPMD, and possibly some classical MD as gromacs.
>
> Thanks,
> Luigi

-- 
Dr. M. F. Somers
Theoretical Chemistry - Leiden Institute of Chemistry  - Leiden University
Einsteinweg 55, P.B. 9502, 2300 RA Leiden, The Netherlands
tel: +31715274437
mail: m.somers*&*chem.leidenuniv.nl
web:  http://rulgla.leidenuniv.nl/Researchers/Somers.htm
room: HB322