[Beowulf] Re: Beowulf Digest, Vol 37, Issue 58

[Håkon Bugge]

Hi Christian,

At 01:19 24.03.2007, beowulf-request at beowulf.org wrote:
>I've yet to see a significant number of message-passing applications
>show that an RDMA offload engine, as opposed to any other messaging
>engine, is a stronger performance determinant.  That's probably
>because there are other equally important and desirable features
>implemented in other messaging engines.


I find this statement hard to justify from 
available benchmark data. Looking at the LS-DYNA 
neon_refined_revised submissions to 
www.topcrunch.org, you can add one in favour of 
RDMA ;-). Scali MPI Connect, utilizing SDR IB, 
performs better than all comparable systems, 
except for one case, where Infinipath is faster. 
This is somewhat surprising to me, given the 
latency and message rate advantage Infinipath has 
compared to traditional IB. Therefore, let me use 
this opportunity to stress that its not only the 
interconnect architecture, but also the software 
harnessing it (read MPI) that matters.

Would be nice though, to evaluate the combination 
of Infinipath and Scali MPI Connect on this case.



Thanks, Håkon