On Fri, Oct 30, 2009 at 12:50 PM, Brian Sheppard <sheppar...@aol.com> wrote: >>> Parallelization *cannot* provide super-linear speed-up. >> >>I don't see that at all. > > This is standard computer science stuff, true of all parallel programs and > not just Go players. No parallel program can be better than N times a serial > version. > > The result follows from a simulation argument. Suppose that you had a > parallel process that performed better than N times a serial program. > Construct a new serial program that simulates the parallel process. There is > a contradiction. > > Technically, this argument only establishes the fact up to multiplicative > constant. But in the case of parallel Go players, I cannot accept that > simulating a parallel process using serial code would result in a slowdown. > (If anything, serialization would be faster.)
At the risk of belaboring the obvious, extra memory associated with each processor or node (cache, main memory, hard disk, whatever) is one reason adding nodes can in practice give a speedup greater than the increase in processing power. It may not be a typical result, but it's not rare, either. It's like when you have two processes that hum along when each given their own machine, but when you try to run them both on the same machine, the system thrashes and runs ten times slower. _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
