Author: Tom Kerrigan
Date: 22:34:27 05/29/00
Go up one level in this thread
On May 30, 2000 at 00:25:29, Robert Hyatt wrote: >On May 28, 2000 at 19:44:05, Tom Kerrigan wrote: > >>On May 28, 2000 at 10:02:05, Georg v. Zimmermann wrote: >> >>>Hi, >>> >>>today I realized that the program I'm toying around with does in its search() >>> >>>1.) generate all moves >>>2.) order the moves and put hash move if available to 1st position >>>3.) do the recursive search >>> >>>I thought that I could increase its speed by testing the hash move first and >>>only if not >= beta do the move generation and the rest. >>> >>>From my tests it shows that it sticks with the hash-move about 50% of the time. >>>Should this number be higher ? >>> >>>I was very dissapointed when I didn't notice any speedup after my changes. What >>>speedup should I expect ? Something like 0.5-1% or more like 1ply ? >> >>You can forget about 1 ply. Your program needs to go ~4x faster for it to search >>1 ply deeper. Which means that your move generator must be taking ~400% of the >>execution time, which is clearly impossible. > > > > >His effective branching factor might be different than yours. Mine is at about >3.0... I have seen some higher and some a bit lower. If you make a program 20% faster, it will not search 1 ply deeper, regardless of your branching factor. (Unless your branching factor is < 1, which doesn't seem likely.) > >> >>Here's what you have to consider when calculating your speedup: >> >>1) How many moves you get from the hash table. I just ran some random position >>and got a 1.75% "hit rate." > >That sounds horribly low. I'd be concerned of something serious if it drops I don't hash during quiescence and my hash table was pretty small when I ran that test. That may explain the low rate. But my point was that the expected speedup of the optimization should be small. Even if you have a hit rate of 50%, the speedup is still only 0.5 * 0.5 * 0.2 = 5%. -Tom
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