**Supercomputer** price/performance (Score 1)

No, I never said anything about a linear scale. I've been doing research in this field for longer than I care to admit, and scaling parallel computers to larger and larger numbers of processors is always a hard thing to do. That is the focus of my research in Sparse FNN technology, to reduce the extra cost of increasing the size of the parallel machine, by making the network cost increase more slowly.

Although KASY0 may be considered "small" by some standards, it defintly merits the definition of "supercomputer". It's theoretical double precision (64-bit) peak is over half a TFLOPS, and over a full TFLOPS for single precision (32-bit), and it uses about 13 kilowatts of electrical power.

Saying that various single processor commodity electronic gadgets get better price/performance is meaningless. The slashdot subject line was too short to add the word supercomputer earlier... it was implied by context.

But again, not to detract from the VT achievment, Big Mac is very impressive. I anxiously await more details on the fault tolerance software they are using, as well as the network toplogy with the 96-port Infiniband switches.

The high percentage of peak Linpack performance of Big Mac on just a subset of it's nodes tells me more about their network topology than anything else. The nature of the Linpack benchmark is that it scales very very well if each node has enough memory (it's operation count scales as the cube, while it's memory references and communications scale as the square). The fact that its efficiency dropped so much on the full machine to me indicates they have some networking bottleneck between switches. It also means that they have a VERY nicely tuned matrix multiply core for within a single CPU or node. Looking at the typical percentage of peak performance numbers on single CPUs from Automatically Tuned Linear Algebra Software (ATLAS), it's difficult to get over 80% peak on just a single CPU.

So, again, the VT machine is VERY impressive.