Author: Uri Blass
Date: 10:12:28 02/15/03
Go up one level in this thread
On February 15, 2003 at 12:59:29, Mike Hood wrote: >On February 15, 2003 at 12:39:18, Robert Hyatt wrote: > >>On February 15, 2003 at 11:43:40, Mike Hood wrote: >> >>>A short quote from Shay Bushink's interview with Mig: >>> >>>I'm not sure our dual Athlon at home would have done much worse. We were >>>somewhat tempted to use the dual because of some initial difficulties we had >>>with the new hardware, but it was a little better on the quad. The >>>eight-processor machine wouldn't have made much of a difference, although there >>>were a few indications that it would have been a bit better in a few situations. >>> >>>http://www.chessbase.com/newsdetail.asp?newsid=799 >>> >>>Are there any users of this forum who run the deep versions of chess programs >>>(Fritz, Junior, Shredder, Crafty) on multi-processor PCs who can give opinions >>>on the performance boost they have observed? >> >> >>I have posted such numbers here many times. Crafty, on a quad at XXX mhz, will >>run anywhere from 2.5X faster to 4.0X faster than a single cpu at XXX mhz. The >>average will be around 3.0 or so. The usual "estimate" I give is this: >> >>speedup = 1 + (NCPUS -1) * 0.7 >> >>And that fits pretty well for an overall "average" speedup. >> >>However, that "formula" has only been tested to eight processors, and _most_ >>of the testing has been on 2 and 4 processors. It is not known (nor even >>expected) that this scaling will hold for larger numbers of processors. But >>for duals and quads, the performance is worthwhile. The 8-way boxes vary >>significantly in performance, depending on how they do memory. For the X86 >>8-way boxes, they simply are not very good. Other 8-way boxes (alphas, SGI >>and the like) seem to do just fine but they max out at 16-way (or maybe 32-way) >>before switching to a NUMA type approach. > >Sorry, Robert, I think I expressed my question inaccurately. I'm not interested >in the speed increase (which is easy to measure), but in the chess playing >strength increase. Is the strength increase achieved by adding a second >processor equal to, less than or greater than replacing it with a single >processor that is 1.7 times as fast? I know, it's difficult to give a >"scientific" answer without playing hundreds of games, but maybe you or someone >else can give an "intuitive" answer. Shay obviously didn't think that the quad >processor used in New York was much better than his dual processor machine at >home. I guess that you may get 40 elo for being 1.7 times faster. Uri
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