Author: Tom Kerrigan
Date: 22:14:38 05/30/00
Go up one level in this thread
On May 30, 2000 at 21:50:19, Robert Hyatt wrote: >On May 30, 2000 at 20:45:17, Tom Kerrigan wrote: > >>On May 30, 2000 at 20:28:17, Robert Hyatt wrote: >> >>>On May 30, 2000 at 18:58:11, Tom Kerrigan wrote: >>> >>>>On May 30, 2000 at 18:01:31, Robert Hyatt wrote: >>>> >>>>>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... >>>> >>>>What improvement does it give you? >>>>-Tom >>> >>> >>>That is complex. So how about this as a starting point: When I added killer >>>moves in crafty, I already had the other stuff present (history, winning >>>captures, hash move, etc.). I added killers and at the same time, started using >>>the more complex "NextMove()" function I now use. Which behaves like this: >>> >>>1. suggest hash move without a move generation, but a direct validation that >>>the move is legal to avoid massive corruption. >>> >>>2. suggest winning captures, and on the first winning capture, make a special >>>case to cull the hash move, should it have been a capture. >>> >>>3. suggest killer moves (2) before generating non-capture moves. I don't allow >>>captures to become killers so there is no chance of duplication there, but I do >>>make sure that the hash move also is not a killer move to avoid replication. >>> >>>4. suggest up to four history moves. The first one is handled separately to >>>screen the entire move list against moves already played so that they are not >>>tried again. >>> >>>5. rest of the moves in order in the list. >>> >>>this speeded me up by about 10%. When I looked at the size of the tree, it had >>>not changed, implying killers were not making the search more efficient. What >>>was happening was that I was avoiding move generations. >>> >>>If you have a specific experiment you want to suggest, I can cobble the code to >>>do whatever you suggest and run the test... >> >>Can you just generate all the moves at the same time and then order them? >>-Tom > > >Yes. Although I don't "order" anything except for winning captures. No need >to order the others. Are you asking me to run with a "generate all moves first" >change to see how it effects speed? Yes, that's the question at hand. -Tom
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