large clusters and topologies

[Joel Jaeggli]

On Fri, 28 Jul 2000, Greg Lindahl wrote:

> > - I suppose Ethernet is not all too efficient with this
> > size, even with switches instead of hubs. What's the largest
> > practical size for an Ethernet 'wulf?
> 
> Depending on the details, Ethernet can work great for larger machines. The
> 1,000 cpu genetic algorithm machine (www.genetic-programming.com) uses
> ethernet, Google's 5,000 cpu cluster uses ethernet, Incyte's 3,000 cpu
> cluster uses ethernet, and so forth. The key is that their application's
> network bandwidth and latency demands aren't maxing out what they have.

that and you can now get fast-ether switches with port-counts up to about
384 ports which isn't to shabby compared to the denisty of most other
lan-interconnects.

as greg describes the real issue of it this is worthwhile or not is
largely a question of where your bottlneck is...
 
> > Any alternatives to Myrinet upwards of that?
> 
> Not really. It depends.
> 
> > - Which type of algorithm can take direct advantage of a cube,
> > toroid, ... topology? I would think even a "dumb" job like
> > matrix multiplication might benefit from a 2D lattice (instead
> > of the typical all-to-all unique segment). Comments?
> 
> There are lots of books which discuss this topic. There have been many
> religious wars fought over the subject.
> 
> -- greg
> 
> 
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