Author: Robert Hyatt
Date: 08:19:04 09/26/01
Go up one level in this thread
On September 26, 2001 at 10:48:14, Vincent Diepeveen wrote: >On September 25, 2001 at 23:44:09, Robert Hyatt wrote: > >you didn't turn off futility bob and i cannot see outputs >in number of nodes and such to see whether sequential overhead >mattered! I don't do futility pruning. I can't turn it off... > >Kopec positions are the worst testpositions ever to use anyway >for obvious reasons that the score only goes up and up and up. Not true. Crafty changes its mind several times per test position... The data shows that the speedup is pretty constant regardless of null-move or not. It would _also_ be constant with or without futility. Older versions had futility pruning and/or razoring. And it had no effect on the parallel search. If you want to make a wager, I will find the CB test positions and run them in the same way. You will see _no_ change in my speedup results, however... > >>Here are the results. First the tests. I took the last 8 kopec positions, >>and searched them to a fixed depth for each null-move setting. 9 plies for >>R=0, 10 plies for R=1, 11 plies for R=2 and 12 plies for R=2~3. >> >>I ran the tests with 1, 2 and 4 processors, and computed the speedup for >>each. The data: >> >>null move R=0----------------------------- >> 1cpu 2cpu 4cpu >>pos17 115 67 40 >>pos18 267 146 77 >>pos19 61 32 17 >>pos20 106 56 30 >>pos21 126 71 36 >>pos22 116 63 33 >>pos23 108 59 31 >>pos24 337 176 90 >> sum 1236 670 354 >> S/U 1.0 1.8 3.5 >> >> >>null move R=1----------------------------- >> 1cpu 2cpu 4cpu >>pos17 42 22 15 >>pos18 76 34 21 >>pos19 32 16 9 >>pos20 35 20 11 >>pos21 30 15 9 >>pos22 51 28 16 >>pos23 68 36 19 >>pos24 144 74 40 >> sum 478 245 140 >> S/U 1.0 1.9 3.4 >> >> >>null move R=2----------------------------- >> 1cpu 2cpu 4cpu >>pos17 39 19 12 >>pos18 121 55 18 >>pos19 27 16 8 >>pos20 34 19 13 >>pos21 20 11 6 >>pos22 43 22 12 >>pos23 58 29 15 >>pos24 83 44 28 >> sum 425 215 112 >> S/U 1.0 1.9 3.8 >> >> >>null move R=2~3--------------------------- >> 1cpu 2cpu 4cpu >>pos17 67 41 26 >>pos18 265 99 60 >>pos19 36 21 12 >>pos20 90 52 27 >>pos21 40 26 15 >>pos22 74 41 21 >>pos23 107 66 39 >>pos24 194 106 51 >> sum 873 452 251 >> S/U 1.0 1.9 3.5 >> >> >> >>The conclusions: >> >>1. Crafty gets roughly 1.9X faster using two processors, regardless of >>the null-move setting. R=0 (no null move at all) to r=2-3, the most >>aggressive setting I use. >> >>2. It averaged a 3.5 speedup for 4 cpus, with R=2 having a slightly better >>speedup for random reasons. >> >>3. Null-move has _zero_ influence on the speedup of a parallel search, as I >>have said _many_ times. All this nonsense about saying that the old programs >>got better speedups without null-move, or better speedups with null-move is >>total baloney. >> >>Anybody else is free to run the same tests... But I prefer to do things a >>bit scientifically by running a test, rather than wild speculation without >>any testing at all. >> >>I can provide the raw data if needed, but it would be a very large post since >>I ran the tests several times to average them.
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