[Beowulf] torus versus (fat) tree topologies

[Richard Walsh]

Ashley Pittman wrote:

>On Fri, 2004-11-12 at 17:51 -0500, Patrick Geoffray wrote:
>  
>
>>Going trough a crossbar cost about 100-150ns these days.
>>    
>>
>
>This isn't necessarily true, we reckon about 25ns on elan4.  This
>doesn't give you perfect latency scaling across very large networks but
>it's very close.
>
>Ashley,
>
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>  
>
Mmm ... from your 2003 Hot Chips presentation on Elan 4 I see 231 
nanos.  Which is right, or are we talking about two different things?

Regards,

rbw
AHPCRC