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Export Controls on Beowulf?
Gary Franczyk writes, "The United States government has tightly controlled the export of "supercomputers" to certain other nations (i.e., China, Pakistan, India, etc.) for quite some time. Sun has had to deal with this numerous times when selling their equipment. How will the U.S. government handle the fact that now anyone with access to large numbers of PCs can create a "super-computer" cluster? I'm sure that the government is using Beowulf to do nuclear simulations right now... Who says that other nations cannot do the same? " Interesting thought. I'm not aware of any export controls on Beowulf, but with the U.S.'s views on cryptography, how will it be before such draconian views extend to any powerful computing technology? Is it even possible for the U.S. to restrict Beowulf in any way?
I guess you haven't been hanging around Slashdot long enough. This came up and was resolved nearly two years ago.
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Name 1 - 1 task - that requires a supercomputer that can't be broken down into nodes well
Sure, I can name several. Just some examples: Weather simulation. Ocean simulation. Molecular simulations. Simulation of astronomical bodies. All of which are very real problems.
In short, any problem which is not trivially parallel will get a much poorer speedup on a NOW (network of workstations) versus a real supercomputer. Many of the problems above will generate many MB/s of data per processor (60 - 200 MB/s is not uncommon).
What you fail to realize is that many problems run for many iterations, and for each iteration you need to distribute the global dataset to all worker nodes. Take the Barnes-Hut program, for example. In that program, each node get a set of close-by astral bodies (stars and planets), and calculates their new positions for the next time step. To do that you need the positions of all other stars. For the next time step, you need to a) collect the calculated positions from all worker nodes, and b) distribute them back for the next iteration. When trying to run that on a NOW, you will very soon find that doubling the size of the cluster will not give any speedup at all, since they will spend most of the time chatting with each other on the network. On a supercomputer, you can run many more worker nodes before this happens.