[Beowulf] single machine with 500 GB of RAM

Jörg Saßmannshausen j.sassmannshausen at ucl.ac.uk
Wed Jan 9 05:05:38 PST 2013


Hi John,

I was toying with this idea as well. However, what I do not know is: as it is 
a single core job, do I really need the second CPU for the memory management 
or would that slow down things? In other words, does it look like that:
Memoryrequest CPU#0 -> CPU#1 -> RAM
So if I am using a single socket motherboard, would that not be faster or does 
a single CPU not cope with that amount of memory?

Regards

Jörg

On Wednesday 09 January 2013 12:53:41 you wrote:
> You will need to populate all of the CPU sockets if you are filing all the
> DIMM slots.
> So yoy probably need more than one CPU
> On Jan 9, 2013 12:42 PM, "Jörg Saßmannshausen"
> <j.sassmannshausen at ucl.ac.uk>
> 
> wrote:
> > Dear all,
> > 
> > Happy New Year!
> > 
> > I was wondering whether people on the list here have some first hand
> > experiences with this. I have been asked to purchase a single machine
> > with around 500 GB of RAM. We would not need more than 8 cores here. The
> > job
> 
> simply
> 
> > needs that much of memory (and even then it is running for 14 days).
> > 
> > Now, with that amount of memory used by a single core, I would have
> 
> thought
> 
> > that I need a fast memory interconnect, i.e. a high memory bandwidth. I
> 
> was
> 
> > thinking of getting an Intel Sandybridge CPU (maybe a  E5-2650) for that
> > machine and get a motherboard with can cope with that amount of memory.
> 
> Does
> 
> > anybody happen to have some recommendations here or knows of potential
> > pitfalls?
> > 
> > Also, in a related problem, how would I set the kernel.shmmni,
> 
> kernel.shmall
> 
> > and kernel.shmmax values so I am not running out of memory handles here.
> 
> I am
> 
> > still confused by that.
> > 
> > Any kind of advice here is much appreciated. Given it is an expensive
> 
> piece of
> 
> > hardware we want to purchase I want to get it right.
> > 
> > All the best from a grey London
> > 
> > Jörg
> > 
> > --
> > *************************************************************
> > Jörg Saßmannshausen
> > University College London
> > Department of Chemistry
> > Gordon Street
> > London
> > WC1H 0AJ
> > 
> > email: j.sassmannshausen at ucl.ac.uk
> > web: http://sassy.formativ.net
> > 
> > Please avoid sending me Word or PowerPoint attachments.
> > See http://www.gnu.org/philosophy/no-word-attachments.html
> > 
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-- 
*************************************************************
Jörg Saßmannshausen
University College London
Department of Chemistry
Gordon Street
London
WC1H 0AJ 

email: j.sassmannshausen at ucl.ac.uk
web: http://sassy.formativ.net

Please avoid sending me Word or PowerPoint attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html



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