interconnect latency, dissected.

Joachim Worringen joachim at ccrl-nece.de
Tue Jul 1 04:03:17 EDT 2003


James Cownie:
> Mark Hahn wrote:
> > does anyone have references handy for recent work on interconnect
> > latency?
>
> Try http://www.cs.berkeley.edu/~bonachea/upc/netperf.pdf
>
> It doesn't have Inifinband, but does have Quadrics, Myrinet 2000, GigE and
> IBM.

Nice paper showing interesting properties.  But some metrics seem a little bit 
dubious to me: in 5.2, they seem to see an advantage if the "overlap 
potential" is higher (when they compare Quadrics and Myrinet) - which usually 
just results in higher MPI latencies, as this potiential (on small messages) 
can not be exploited. Even with overlapping mulitple communication 
operations, the faster interconnect remains faster. This is especially true 
for small-message latency.

>From the contemporary (cluster) interconnects, SCI is missing next to 
Infiniband. It would have been interesting to see the results for SCI as it 
has a very different communication model than most of the other interconnects 
(most resembling the T3E one).

 Joachim

-- 
Joachim Worringen - NEC C&C research lab St.Augustin
fon +49-2241-9252.20 - fax .99 - http://www.ccrl-nece.de

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