[Beowulf] performance tweaks and optimum memory configs for a Nehalem

Rahul Nabar rpnabar at gmail.com
Tue Aug 11 18:24:04 EDT 2009


On Tue, Aug 11, 2009 at 12:19 PM, Mikhail Kuzminsky<kus at free.net> wrote:
> If this results are for HyperThreading "ON", it may be not too strange
> because of "virtual cores" competition.
>
> But if this results are for switched off Hyperthreading - it's strange.
> I have usual good DFT scaling w/number of cores on G03 - about in 7 times
> for 8 cores.

Yes, it is very strange and I still cannot explain it very well. Do
you have scaling info for VASP? You did mention DFT codes so I was
wondering. I still haven't found much info for VASP on Nehlems. Maybe
it is some feature of this particular code. All the other tests make
sense.

And I just find it hard to believe that the Nehalem which has been so
far touted to be such a good proc. can be outperformed by by one year
old AMD Barcelonas.......I feel it's something I am doing wrong.

-- 
Rahul
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