ATM Gigabit & Myrinet

> What are your impressions concerning Myrinet compared to Fast Ethernet?
> Has anybody ever used both for some time? Is it worth the added cost,
> or, rather: was it worth the added cost for your code? (and what code
> are you running?) Any experiences concerning scalability (for medium
> sized systems, 128 to 256 nodes)? Is it better in every respect compared
> to Fast Ethernet (apart from cost)? How much faster did your code
> run? (And do you know why?)

It depends. For some apps, fast ethernet is enough, and anything faster
consumes money better spent on additional nodes (costs are about $10K -
$13K USD for an eight node network using either Giganet, Myrinet, or
Gigabit ethernet.).

On the other hand, if you are bandwidth and/or latency sensitive, one of
those networks could be worth far more than additional nodes.

While Giganet, Myrinet, and gigabit ethernet all provide similar
bandwidths, gigabit ethernet has about the same latency as fast
ethernet, so it's not a great deal unless you need the system support,
e.g., TCP/IP. Myrinet and Giganet are both application-level networks,
that is, your app (e.g., MPI libraries) need to deal with the network --
this is one of the reasons for the low latency.

So, as always, the answer will depend upon the specific application you
have in mind. If you can find benchmarks for your app or a similar one,
you're in luck. If not, then be very careful about the conclusions you
draw.

Thanks,