[LINK] Fwd: Cray readies Linux systems-large-scale cluster

[hartr@redhat.com]

On 30 Jan, Rick Welykochy wrote:
> We've noticed that the latest PC's running 1GHz CPUs are in the
> 'supercomputer ' class. An early player in the original supercomputer
> stakes is now employing Linux in large-scale clustered systems to
> provide

This sort of statement is unfortunate.

There is one area in which Beowulf cluster type super computers (which
these days generally run Linux) seriously lag behind 'big iron' super
computers - memory bandwidth.

Depending on the sort of application that you are processing, this can
have a serious effect on the application performance on such a computer.

Although 64bit CPUs suhc as the Alpha have (generally) better memory
bandwidth that 32 bit CPUs, this is still orders of magnitude lower than
the typical memory bandwidth of a 'big iron' super computer.

Memory bandwidth has a significant effect in a number of areas -
handling large data sets is one and another is parallel applications
with a significant inter-process communication load.

I would therefore not call *any individual* 'PC' a member of the
'super computer class - and I would be hesitant about suggesting that a
Beowulf cluster type super computer offered the same or better
performance as a 'big iron' supercomputer - because it depends
significantly upon the application that you are trying to run.

-- 
Robert Hart						 hartr@redhat.com
Red Hat Asia-Pacific, Unit 15, 23 James St, Brisbane, Qld 4006, Australia
Tel +61 (0)7 3872 4808                             Fax +61 (0)7 3257 4800