[Beowulf] 1.2 us IB latency?
hahn at mcmaster.ca
Wed Apr 18 09:38:18 PDT 2007
> Nothing was broken in the previous InfiniBand adapters. The previous
> generation, with higher MPI latency still beat other solutions that
> shows lower latency, due to the fully offload architecture.
look, that's just not true. I've got a cheap, low-end cluster which
uses plain old myri2g and mx, and has for ~3 years. 3 us latency.
IB was more like 6-8 us (at the mpi level, of course) three years ago,
and with the exception of your new promised adapters, is still not
faster than 2g-mx...
> We gain experience from each generation and implement it in the next
> generations, and this is the outcome.
thanks, I needed my daily dose of marketing-speak. unfortunately,
the question remains unanswered. gradual improvement does not explain
a 3x improvement.
> There are no special requirements for achieving this MPI latency, and
> we are very happy to provide low latency without changing the offload
> concept of our architecture.
OK, so what's unique about your offload concept? it's obviously not the case
that you're the first to do offload.
>> also, just to be perfectly explicit, this is 1.2 us
>> inter-node, right? not something crazy like two 8-core boxes
>> with only two of 16 hops inter-box?
> 2 nodes connected via InfiniBand - regular setting. There is no
> dependency on the
> numbers of cores, as we don't need to CPU to drive the interconnect.
sniping at infinipath aside, thanks for the confirmation.
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