Author: Vincent Diepeveen
Date: 19:48:03 09/24/01
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On September 23, 2001 at 22:59:00, Robert Hyatt wrote: >On September 23, 2001 at 17:46:28, Vincent Diepeveen wrote: > >> >>This is utterly nonsense. i spent hundreds of programming hours trying >>to improve move ordering. My move ordering is *better* and more code >>than most programs. Probably more than them all. Of course i NEED to >>because DIEP's evaluation function is *way* bigger than anything elses >>evaluation function, with exception of the average chessplayer (already >>half a century ago the number of patterns a masterclass player has, has been >>estimated at 100000). >> >>It is of course way easier to dynamically get a better tree in parallel >>than write zillions of source code lines which btw also slow down the program! >> >>One thing all you guys seem to miss, and which is *impossible* that it >>gives Bob the same speedup. >> a) more extensions means that both processors search less in the same >> space so speedup is less then >> >>So the default diep version has a bad speedup, like 1.8 and also at slower >>time controls that doesn't seem to get better, but when i throw all >>dangerous extensions outside of it, then the speedup *does* get better. >> >>Note that results from programs like crafty can never get taken serious >>because of futility pruning. The influence at the tree at bigger >>depths from futility is *way* bigger than that of a parallel search. >> >>Note that for computerchess any todays P3 would kick the hell out of that >>Crafty YMP from 15 years ago. And no it is *not* equivalent to 200Mhz >>even. >> >>I have some old paper from Bob here describing the Cray Blitz hardware >>from some years ago. Let me find it! > >You don't need to find it. In 1986 we were running on a machine called the >"cray Y-MP". Clock speed was 6 nanoseconds per cpu. which is nearly 200mhz. >It had 8 processors. And it could execute at least 2 instructions every clock >cycle per cpu... which would blow off any 200mhz machine you care to drag up. May i beg your pardon, from Pentium pro and on the cpu's can do 3 a clock. But be my guest. You claim average speedup of 11.1 at 16 processors Cray. That's 11.1 x 0.2Ghz = 2.22Ghz. That's 2 instructions a clock at most. I do not need bandwidth for my chessprogram. I am happy that nowadays processors do 3 instructions a clock at most. P4 even on paper 4, but they have proven theoretically that current design cannot do it yet (unless intel has not told the entire truth about the processor which is very well possible too). Note that 21264 does 4 at most. I do not know how much penalties each misprediction got in these days, that's not interesting anyway, because there are tools to measure the average number of instructions that execute each clock. For crafty that's around 2 at nowadays cpu's. So a modern cpu definitely isn't slower for it. So any of todays dual AMDs easily kicks with 2 x 1.4Ghz = 2.8 Ghz a 2.22Ghz 16 processor YMP from a year or 15 ago which costed back then 80 million dollars and perhaps another 10 million dollar for power, support personal and cooling water statoin. there's more about your hardware which has to do with complex instructions. I will come back onto this! >That old YMP had so much more memory bandwidth than the PCs of today it really >doesn't make sense to compare them. > > > >> >> >> >>Best regards, >>Vincent >> >>>Dave
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