[Beowulf] memory bandwidth scaling

[Jason Riedy]

And I write:
> Depends on the actual machine cost and your applications' needs.
> I've seen 1TiB, 4 CPU machines with a cost less than two 256GiB,
> 2 CPU machines.

Amusing timing.  Thanks to IBM's LC-series press release, I
double-checked the pricing.  It's even less to just click and
order the 1TiB system now, although I can't give an explicit
number because I'm going through the institutional pricing site.
Also beats the price IBM is using for comparison (even adding the
Fibre Channel bit), but I'm sure negotiations matter.  Although
the price is well below the "contact us" level for individual
machine purchases.  Odd.

HMC/HBM/etc. else really could change everything related to this,
once they're generally obtainable.  "Tall" nodes are gonna be
cool again someday, really.  Until they're not again.