[Beowulf] cluster building advice?

[Mark Hahn]

> If i want to slowdown factor 2 with some software i don't need to

can you show an example of where using even a year-old release of gcc 
causes a factor of 2 slowdown?  especially for middleware or the kernel.

for actual applications, a factor of 2 is surprising but not unbelievable,
simply because any system will spend most of its time in the application!
kernel and middleware are simply not normally hotspots.