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Zobrist alternative?
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Wylie Garvin



Joined: 05 Jul 2007
Posts: 657
Location: Montreal, Canada
PostPost subject: Re: Zobrist alternative?    Posted: Thu Jun 14, 2012 6:11 pm Reply to topic Reply with quote
hgm wrote:
I measured the penalty for such a cache-line-straddling access, and it was very low. (On Intel Celeron M; I would not know about AMD.) Within the cache line there was no penalty whatsoever.

But with a 0x88 board, the key table can be positioned in such a way that the cache line is never exceeded. (By starting the board at a cache line, the 4th rank of the board would be at address 48-55, and even the access for h4 would span 55-62. a5 would map to the start of the next cache line.

Of course on other architectures (ARM?) such tricks are likely to cause exceptions ('bus error'). i386 is really exceptional in allowing non-aligned access.


The other thing you can do (as long as you have less than about 56 piece types) is use one cacheline per square (or per two squares), and add pieceNumber (or perhaps 2*pieceNumber) to the address. E.g. for standard chess with piece numbers in the 1-12 range or so, you could use something like (sq*32 + pieceNumber*2) and you'll never cross a cache-line boundary. The table is a little bigger (maybe 1/3rd of the size of a table that uses no overlapping? can't remember off the top of my head) but it still helps.

If you really need to have more than 55 piece types, maybe its worth skipping some of the piece numbers. I.e. use piece numbers 1-56 and 65-120, etc. but don't use the numbers 57..64. Then you can always index into your zobrist table without crossing a cacheline boundary.
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Subject Author Date/Time
Zobrist alternative? H.G.Muller Tue Jun 12, 2012 7:35 pm
      Re: Zobrist alternative? Kevin Hearn Tue Jun 12, 2012 7:44 pm
      Re: Zobrist alternative? Daniel Shawul Tue Jun 12, 2012 8:19 pm
            Re: Zobrist alternative? H.G.Muller Tue Jun 12, 2012 8:54 pm
                  Re: Zobrist alternative? Daniel Shawul Tue Jun 12, 2012 9:46 pm
                        Re: Zobrist alternative? Daniel Shawul Wed Jun 13, 2012 3:24 am
                        Re: Zobrist alternative? Daniel Shawul Wed Jun 13, 2012 4:14 am
                              ignored idea here Daniel Shawul Wed Jun 13, 2012 4:00 pm
                                    Re: ignored idea here Daniel Shawul Thu Jun 14, 2012 1:30 am
                                          Re: ignored idea here H.G.Muller Thu Jun 14, 2012 5:50 am
                                                Re: ignored idea here Daniel Shawul Thu Jun 14, 2012 12:52 pm
                                          Re: ignored idea here Edmund Moshammer Thu Jun 14, 2012 8:21 am
                                                Re: ignored idea here Edmund Moshammer Thu Jun 14, 2012 9:27 am
      Re: Zobrist alternative? Wylie Garvin Tue Jun 12, 2012 8:27 pm
            Re: Zobrist alternative? H.G.Muller Tue Jun 12, 2012 8:36 pm
                  Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 1:01 pm
                  Re: Zobrist alternative? Wylie Garvin Wed Jun 13, 2012 10:57 pm
                        Re: Zobrist alternative? H.G.Muller Thu Jun 14, 2012 5:42 am
                              Re: Zobrist alternative? Robert Hyatt Thu Jun 14, 2012 1:17 pm
                                    Re: Zobrist alternative? H.G.Muller Thu Jun 14, 2012 2:17 pm
                                          Re: Zobrist alternative? Wylie Garvin Thu Jun 14, 2012 6:11 pm
                        Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:05 am
      Re: Zobrist alternative? Reinhard Scharnagl Wed Jun 13, 2012 9:52 am
            Re: Zobrist alternative? Edmund Moshammer Wed Jun 13, 2012 9:58 am
                  Re: Zobrist alternative? Reinhard Scharnagl Wed Jun 13, 2012 12:49 pm
                        Re: Zobrist alternative? Edmund Moshammer Wed Jun 13, 2012 1:15 pm
                              Re: Zobrist alternative? Reinhard Scharnagl Wed Jun 13, 2012 1:41 pm
                                    Re: Zobrist alternative? Edmund Moshammer Wed Jun 13, 2012 3:55 pm
                                          Re: Zobrist alternative? Reinhard Scharnagl Wed Jun 13, 2012 4:03 pm
      Re: Zobrist alternative? H.G.Muller Wed Jun 13, 2012 2:19 pm
            Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 2:44 pm
            Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 2:48 pm
                  Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 3:28 pm
                  Re: Zobrist alternative? H.G.Muller Wed Jun 13, 2012 4:01 pm
                        Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 5:42 pm
                              Re: Zobrist alternative? H.G.Muller Wed Jun 13, 2012 5:51 pm
                        Re: Zobrist alternative? Vincent Diepeveen Wed Jun 13, 2012 6:27 pm
            Re: Zobrist alternative? Daniel Shawul Wed Jun 13, 2012 5:29 pm
            Re: Zobrist alternative? Karlo Bala Jr. Thu Jun 14, 2012 9:50 am
      Re: Zobrist alternative? Reinhard Scharnagl Thu Jun 14, 2012 8:49 am
            Re: Zobrist alternative? H.G.Muller Thu Jun 14, 2012 9:09 am
            Re: Zobrist alternative? Daniel Shawul Thu Jun 14, 2012 1:11 pm
                  Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:12 am
      Re: Zobrist alternative? Don Dailey Thu Jun 14, 2012 4:46 pm
            Re: Zobrist alternative? Don Dailey Thu Jun 14, 2012 6:38 pm
                  Re: Zobrist alternative? Daniel Shawul Thu Jun 14, 2012 6:57 pm
                        Re: Zobrist alternative? Don Dailey Fri Jun 15, 2012 2:39 pm
                              Re: Zobrist alternative? H.G.Muller Fri Jun 15, 2012 3:46 pm
                                    Re: Zobrist alternative? Daniel Shawul Fri Jun 15, 2012 5:22 pm
                                          Re: Zobrist alternative? H.G.Muller Fri Jun 15, 2012 5:38 pm
                                                Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:17 am
                              Re: Zobrist alternative? Daniel Shawul Fri Jun 15, 2012 5:04 pm
                                    Re: Zobrist alternative? Don Dailey Fri Jun 15, 2012 6:00 pm
                                          Re: Zobrist alternative? Daniel Shawul Fri Jun 15, 2012 7:27 pm
                                                Re: Zobrist alternative? Don Dailey Fri Jun 15, 2012 8:16 pm
                                                      Re: Zobrist alternative? Daniel Shawul Fri Jun 15, 2012 8:42 pm
                                                      Re: Zobrist alternative? Daniel Shawul Fri Jun 15, 2012 9:14 pm
                                                            Re: Zobrist alternative? Don Dailey Fri Jun 15, 2012 10:59 pm
                                                                  Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 12:17 am
                                                                        Re: Zobrist alternative? Don Dailey Sat Jun 16, 2012 4:28 am
                                                                              Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 6:30 am
                                                                                    Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 10:09 am
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:22 am
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:42 am
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 10:54 am
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 11:03 am
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 11:08 am
                                                                                          Re: Zobrist alternative? Don Dailey Sat Jun 16, 2012 12:03 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 12:55 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:21 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:25 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:44 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 12:35 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 1:11 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 1:15 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 1:56 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:05 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:10 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:22 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:29 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:35 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:39 pm
                                                                                          Re: Zobrist alternative? Don Dailey Sat Jun 16, 2012 3:49 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 4:35 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:11 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:13 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:19 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 2:29 pm
                                                                                          Re: Zobrist alternative? Vincent Diepeveen Sat Jun 16, 2012 2:32 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 4:19 pm
                                                                                          Re: Zobrist alternative? Don Dailey Sat Jun 16, 2012 4:50 pm
                                                                                          Re: Zobrist alternative? Daniel Shawul Sat Jun 16, 2012 4:25 pm
                                                Re: Zobrist alternative? Don Dailey Fri Jun 15, 2012 8:21 pm
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