myrinet vs gigabit

[Ole W. Saastad]

> Woo Chat Ming wrote:
> 
> >  I am going to set up a 100-nodes beowulf cluster
> > to do scientific simulation. Is Gigabit ethernet or
> > Myrinet better ? Does anyone has performance comparation
> > of them ?

When making judgements about what interconnect to make, the interesting
parameters depend on your appication requirements. Are your applications
communication intensive, and if they are, what is the mix between long
and short messages, the amount of collective operations and simultaneous
traffic etc. etc.

These are all important parameters and they vary with the appplication
and
the way the algorithms are designed. If you do not know enough of these
parameters and their importance for your system, a sound way to act is
to optimize bandwidth and minimize latency to build a system that
performs
well for most possible applications.

Then there are other arguments like fault scalability (systems with
switches do not scale well above certain limits due to the complexity
of cross-bar switches) fault resilience (systems with switches have a
single point of failure) and bisection bandwidth.

It is also important to point out that the performance numbers that you
find for the different networks are not necessarily true for all
combinations of processors and PCI bridge interface chip-sets. The
performance of the bridge chip set can vary significantly and you have
to select the right combination to get the optimum performance from your
interconnect.

Last but not least, what kind of software is available for the network
and cluster management and what kind of knowledge and experience do
you have to put it all together and to tune it to work well with your
combination of hardware and software.





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Ole W. Saastad, Dr.Scient.    |      Scali AS        | Scalable Linux
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