[Beowulf] Intel quad core nodes?

[Tim Cutts]

On 8 Oct 2007, at 6:17 pm, Barnet Wagman wrote:

> I'm moving towards setting up a small cluster (my first), and am  
> thinking about using Intel quad core processors.  However, I'm a  
> little concerned about memory contention.  I'm (tentatively) going  
> to have one processor per node (this appears to be the cheapest way  
> to go), but I still wonder whether four cores will choke Intel's  
> memory architecture.  (AMD's Barcelona may be better in this  
> regard, but it doesn't seem to be available yet, at least not  
> through retail channels).
>
> I'd like to hear any opinions on this issue.  And if you've used  
> quad core processors, I'd certainly like to hear about your  
> experiences (including which processor you've used).

Well, whether it's an issue or not, it's something we're all going to  
have to deal with, since neither Intel nor AMD are offering us any  
choice in the matter in the years to come.

We do have some Intel quad core machines in our cluster, which runs  
embarrassingly parallel single-threaded workloads.  Given that  
workload, I was expecting to see serious memory contention effects.   
Our applications are by no means tightly written, and they are memory- 
intensive.  But I haven't seen much of a problem with the Intel quad- 
core CPUs we have.  They achieve very good throughput on these tasks.

How much further this will go, I do not know. Once we start getting 8  
cores and more, who knows.  We'll hit a wall at some point, I just  
don't know when.

For more traditional HPC workloads, I don't know how well they work.   
As with all these things, obtain a test machine or two, and benchmark  
your code...

Regards,

Tim


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