[Beowulf] New HPCC results and the Myri viewpoint  Stuart
Midgley sdm900 at gmail.com Thu Jul 21 00:59:55 EDT 2005
Actually, I tend to disagree with your comment here.  The curve
tells   you one of the characteristics of the network, which is
VERY useful   in evaluating a network before you expend
time/effort testing your   code on it (assuming you know your
code well).  On its own (without   lots of other micro
benchmarks) I agree that it is useless.  In my own experience, I
tend to find that most codes are not latency   sensitive (that
is, QsNetII, Infinipath, Myricom etc are effectively   the same,
on a latency sense, to most codes)... until they try and   scale
to the 1000's of cpu's.  All of a sudden simple things like
barriers and synchronisation etc can become expensive on
networks   with higher latencies.  Things that the software
writer wasn't   expensive start to dominate their code.  Hence,
the ping-pong   latencies and ring latencies are useful in
giving you an idea of how   well the larger cod