Re: tlug: Interesting new server

["Manuel M. T. Chakravarty" <chak@example.com>]

Hi!

I enjoyed the nomikai very much!

> RESEARCH TRIANGLE PARK, N.C., May 12 /PRNewswire/ -- Red Hat Software, Inc.,
> publishers of the award-winning Red Hat Linux Operating System, today announced
> the $29.95 high performance computer.
> 
> Called Extreme Linux, and also known as The Beowulf Project, this collaboration
> between Red Hat Software, NASA Goddard Space Flight
> Center, and over two dozen leading research centers will
> bring the speed and power of multiple computers--parallel
> processing as one computer--to students, researchers, and
> end-users worldwide.

This is definitely an interesting project and one of the
members of the Beowulf project (might even be the leader)
wrote and maintains the 3c59x.c ethernet driver, which I use
myself, but nevertheless, I think this announcement is a bit
too optimistic.  This is for a hardware and a software
reason.  Hardware: Even a 100MBit Ethernet is a joke
compared to the networks used in `real' parallel machines.
Just consider that, e.g., the Cray T3E provides each
processing node with three bidirectional 600MByte links
(plus an I/O connection, which in itself is comparable to
FastEthernet); the latency in such a network is similarly
more advanced (i.e., smaller) than in an Ethernet
connection.

Software: Unfortunately, here Linux is the problem.
Although, the networking code in Linux is quite good for a
conventional operating system, the administrative overhead
incurred by a user program that wants to inject some data
into the network is rather high.  A current trend in OSs for
parallel machines is to allow user programs direct access to
the networking hardware, i.e., the expensive kernel entry,
buffer copying etc. is avoided.  Of course, it is not easy
to allow direct hardware access and still guarantee the
integrity of other process on the machine (one possibility
is too use special hardware to support this).

Extreme Linux is surely interesting for some applications,
but `high performance computing' is still something quite
different.

Cheers,

Manuel
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