>Don't forget the additional costs of double the number of uniprocessor
>boxes in terms of power, air conditioning, and maintenance. All of
>these make CPU density more important again.
>
>On small processor farms, this might not be so important, but once you
>get into the realm of thousands of CPUs it makes an enormous difference.
>
>Tim.
True. But to extend my original example, the Dual Athlon boxes take almost
as much juice as 2 single boxes, and the MTBF on contemporary PC parts is
such that you wouldn't expect significantly more failures on double the
number of parts. This snippet is from
http://www.theinquirer.net/11050104.htm...
"That 460W power budget results from the use of two 1.8GHz Athlon
Processors (180 Watts), motherboard with 4GB memory (75 Watts), AGP Pro
Card (50 Watts), 2 SCSI HDD (75 Watts), CD-ROM & Floppy (20 Watts), 3 PCI
Cards (45W) plus keyboard, mouse and USB devices (10W)."
Sure, us clusterers will be able to build this a little more efficiently
but you see my point. If your goal is a good price / performance ratio,
then I maintain the SMP solutions haven't broken in yet, and they are the
leading candidate for increasing density. Because it is difficult to
calculate performance before you buy the equipment, I have just been using
overall budget to overall cycles (or some other aggregate number) as a
predictive ratio. So you don't cross your price break point until you are
building a very large cluster.
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