Author: Robert Hyatt
Date: 15:01:31 05/30/00
Go up one level in this thread
On May 30, 2000 at 17:57:30, Tom Kerrigan wrote: >On May 30, 2000 at 17:24:29, Gian-Carlo Pascutto wrote: > >>On May 30, 2000 at 14:54:28, Tom Kerrigan wrote: >> >>>I assume that when Bob says he expects a 25% hit rate, he means 25% of the >times that the hash table is probed, and not 25% of the nodes. >> >>Probably yes, so did I... >> >>>Which means that more work needs to be done to estimate the speedup from the >optimization that started this thread, i.e., the equation becomes: >>> >>>speedup = (% hit rate) * (% hash probes) * (% hash move cutoffs) * (% of time >>>spent doing move generation) >>> >>>Throwing in some extremely optimal numbers, the result is: >>> >>>0.5 * 0.2 * 0.5 * 0.2 = 1% >>> >>>So I think the best you can hope for is 1%. Seems like too much work for too >>>little, to me. >> >>If you do the same optimization for killer moves, how much can you hope for >>then ? >> >>This would be (killer move cutoffs) * (time doing move generation), right ? >> >>The second term is pretty high for me, so I'm interested to know what the >>first one will be. Anybody got any numbers on this ? >> >>-- >>GCP > >Depends on how you generate moves... > >Captures should be ordered higher than killers, so you have to generate >captures. For me, if you're generating captures, you might as well generate all >the moves while you're at it. > >Don't forget, there's also some overhead in bypassing move generation. You have >to keep track of which "stage" of move generation you're in. You have to make >sure you don't search the same move twice. And you have to test the legality of >hash and killer moves. Basically, this is overhead on an improvement that's >already small. Not worth it, in my opinion... > >-Tom It definitely works for me...
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