[Beowulf] Register article on Cray Cascade

Vincent Diepeveen diep at xs4all.nl
Fri Nov 9 08:17:34 PST 2012


The latency estimate taking 5 hops seems a tad optimistic to me  
except when i read the English wrong and they mean 1.7 microseconds a  
hop making it for a 5 hop 5 * 1.7 = 8.5 microseconds in total.

"Not every node is only one hop away, of course. On a fully  
configured system, you are five hopes away maximum from any socket,  
so there is some latency. But the delta is pretty small with  
Dragonfly, with a minimum of about 1.2 microseconds for a short hop,  
an average of 1.5 microseconds on average, and a maximum of 1.7  
microseconds for the five-hop jump, according to Bolding."

On Nov 8, 2012, at 7:13 PM, Hearns, John wrote:

> Well worth a read:
>
>
>
> http://www.theregister.co.uk/2012/11/08/ 
> cray_cascade_xc30_supercomputer/
>
>
>
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