[Beowulf] fast interconnects, HT 3.0 ...

Eugen Leitl eugen at leitl.org
Tue May 23 07:50:26 PDT 2006

On Tue, May 23, 2006 at 08:49:08AM -0500, Richard Walsh wrote:

>    Speaking of Hyper Transport 3.0 and its AC chassis-to-chassis 
> capabilities and 10 to 20
>    Gbps performance maximums one-way (non-coherent, off chassis I 
> believe), what do the
>    people that know say about scalability.  Are we looking at coherency 

I don't know (like it would stop me), but there are few-port HT switches,
and if there are several ports on one chassis one could wire up
some topology, which, hopefully, will match the problem. 

> within the board complex
>    and basic reference ability off board or something else?

I'm not sure how this is different from vanilla packet-switched
MPI network. It's not about maintaining memory coherency.
>    Sounds like the Cray X1E pGAS memory model.  Is there a role for 

I don't think there is any other model but message passing. It's not
like this is a ccHT a la HORUS http://en.wikipedia.org/wiki/HORUS_interconnect

> switches?  And then there is the
>    its intersection with the  pGAS language extensions (UPC and CAF) 
> ... raising the prospect of
>    much better performance in a commodity regime, with possible 
> implications for MPI use.
>    Anyone have a crystal ball or insights on this?

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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