I imagine a hybrid topology of certain sized subclusters connected internally with a right topology for their size, and the subclusters connected to each other with some other topology, etc. The way cores on a chip are connected is different obviously from the way chips on a board, or boards on a backplane, or boxes to routers, or routers to metarouters...and I need hybrid-ness so that the optimization/self-reconfiguring algorithm can do something with its platform.
So maybe just some scale component or subcluster would be hypercube, some FNN, some tree, I don't know. I want enough wires with enough nodes so that my application can tell **me** what topology works best for a compuational category of applications. Peter On 7/25/08, Lawrence Stewart <[EMAIL PROTECTED]> wrote: > > Mark Hahn wrote: > >> It is my sacred duty to rescue hypercube topology. Cool Preceeds > >> Coolant :-) > > > > I agree HC's are cool, but I think they fit only a narrow ecosystem: > > where you don't mind lots of potentially long wires, since higher > > dimensional > > fabrics are kind of messy in our low-dimensional universe. also, HC's > > assume intelligent routing on the vertices, so you've got to make the > > routing overhead low relative to the physical hop latency. > > > > it does seem like there is some convergence to using rings onchip, > > fully connected graphs within a node and fat trees inter-node. > > one unifying factor is that these are all point-to-point topologies... > > Hypercubes give log diameter, which is good, but when you grow the machine > you have to add more ports to each node, which is not so good once you run > out of pins. > > Other topologies, such as Kautz and deBruijn graphs, give log diameter > as well, > but with a fixed number of ports per node, so you can put the node on > one chip > and still build systems of greater or lesser size without having to respin. > > You can route arbitrary size Kautz graphs on a > fixed number of layers, so when these somewhat wacky topologies > go on chip you can still route it on N metal layers. > > The point about long wires is well taken, but I think it is the price of > low diameter. > > > -- > -Larry / Sector IX > >
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