[Beowulf] Slection from processor choices; Requesting Giudence

[Vincent Diepeveen]

> - The network/MPI combination is fairly critical to good performance and 
> to
> price/performance. I have done some benchmarks where the right MPI library
> on GigE produces faster results than a bad MPI library on Myrinet. Seems
> counter-intuitive, but I've seen it.
> Jeff

Jeff, we know how some people can mess up installs, but if you have gigabit 
ethernet,
with a one way pingpong latency of like 50-100 us if you're lucky, which is 
not using DMA i
guess by default; in short nonstop interrupting your cpu,
versus newer myri cards that are probably under 3 us, factor 20 to 30 
advantage to
myri then you need to really not manage to install the network to let 
gigabit ethernet work better.

That said it's not easy of course to install the network, but let's not 
assume that someone who
builds a cluster doesn't manage to install the hardware he gets.

For that huge amount of money from the highend manufacturers that you pay 
for their hardware, you
DO get great support if you really don't manage to install it.

There is not really exceptions to that.

Vincent

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