[Beowulf] slightly [OT] smp boxes

[Joe Landman]

Nifty niftyompi Mitch wrote:
> On Fri, Oct 17, 2008 at 12:26:54PM -0400, Joe Landman wrote:
>> andrew holway wrote:
>>> Hi
>>>
>>> If you wanted to buy an smp machine of 8, 16 or 32 sockets, what would
>>> be your options?
>> x86 architecture?  Others?
> 
> To what purpose?
> Why so many sockets, for Beowulf?

You would have to ask Andrew, though we have seen folks needing huge 
memory spaces as the driving factor for single systems with many sockets 
and lots of ram.  In fact, at least one hedge fund we know went this route.

> The Sicortex system has lots of cores and some of their smaller
> development systems and might qualify if the goal is to research
> SMP, NUMA, and single system memory image.

I don't know if you would call them SSI, and I don't remember if they 
have strict coherency within them.  This said, they have a very fast and 
scalable fabric.  It is an interesting system.  Not a commodity box, but 
quite interesting.

> As fast as CPU cores are today, memory and coherency protocols will hobble
> the system in unexpected ways....  In some cases Infiniband bandwidth

Yup.

> between single and dual socket systems is an improvement over large socket
> count boxes.   For some chassis large socket counts permit more RAM...

This is the important thing.  I still don't see 8GB DIMMs as being 
affordable for most users.  I hope this changes soon.


-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
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