[Beowulf] scalability

[Tom Elken]

> > The older Woodcrest/Clovertown type CPUs had the
> > standard Intel bottleneck of a single memory
> > controller for both sockets.
> 
> Yes, that is for fact, but didn't the
> Harpertown generation still have a similar problem?

Yes.

> 
> Amjad's Xeon small cluster machines are dual socket dual core,
> perhaps a bit older than the type I had used here
> (Intel Xeon 5160 3.00GHz) in standalone workstations
...
> According to Amjad:
> "I have, with my group, a small cluster of about 16 nodes
> (each one with single socket Xeon 3085 or 3110;
> And I face problem of poor scalability. "
> 
> I lost track of the Intel number/naming convention.
> Are Amjad's and mine Woodcrest?

Yours (Xeon 5160) are Woodcrest.
Amjad's are Conroe (Xeon 3085) and  Wolfdale (Xeon 3110).  

But they all appear to be very similar.  A good reference is:
http://en.wikipedia.org/wiki/Xeon#3000-series_.22Conroe.22
and further down the page.
Microarchitecturally they are probably virtually identical.  Main differences  differences in 
- L2 size (Wolfdale (Xeon 3110) had 6MB, and the others 4MB, all shared between 2 cores),
- power dissipation, 
- process size, and 
- max # of CPUs in a system.

-Tom

> Clovertown?
> Harpertown?
> 
> > The newer Nehalem Xeon's have HyperTransport^W QPI
> > which involves each socket having its own memory
> > controller with connections to local RAM.
>