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"Simplified ABDADA" updated
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Tom Kerrigan



Joined: 03 Jul 2015
Posts: 64

PostPost subject: "Simplified ABDADA" updated    Posted: Tue Aug 29, 2017 5:11 am Reply to topic Reply with quote

Hi all, thanks to feedback from this forum, I've updated my "Simplified ABDADA" algorithm:

http://www.tckerrigan.com/Chess/Parallel_Search/Simplified_ABDADA/

It turns out that hash table collisions were an issue for currently_searching (the hash table that stores hashes of moves that are currently being searched).

I switched it to a 4-way hash table which solved the problem very neatly. The code is still very simple, doesn't require any locks, there's basically no impact on performance (NPS), and at no point in my testing was there a need for more than 4-way associativity.

I also redid all my speedup testing and updated the numbers on this page:

http://www.tckerrigan.com/Chess/Parallel_Search/

The speedups are all basically the same. Actually I think they are probably a tiny bit slower on average, by maybe 1-2%. I guess having multiple threads randomly search the same move sometimes provided a little benefit, but I'd rather have the peace of mind of knowing the algorithm is working as intended!
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Display posts from previous:   
Subject Author Date/Time
"Simplified ABDADA" updated Tom Kerrigan Tue Aug 29, 2017 5:11 am
      Re: "Simplified ABDADA" updated Michel Van den Bergh Tue Aug 29, 2017 6:23 am
            Re: "Simplified ABDADA" updated Tom Kerrigan Tue Aug 29, 2017 6:34 am
                  Re: "Simplified ABDADA" updated Nicu Ionita Fri Nov 24, 2017 2:16 pm
                        Re: "Simplified ABDADA" updated Tom Kerrigan Sat Dec 02, 2017 6:30 pm
                              Re: "Simplified ABDADA" updated Nicu Ionita Tue Dec 05, 2017 9:40 am
      Re: "Simplified ABDADA" updated Jean-Christophe WEILL Wed Dec 13, 2017 7:47 pm
            Re: "Simplified ABDADA" updated Tom Kerrigan Thu Dec 14, 2017 2:17 am
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