Author: Robert Hyatt
Date: 20:44:09 09/25/01
Go up one level in this thread
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.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.