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YBWC: Active Reparenting
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Robert Hyatt



Joined: 27 Feb 2006
Posts: 15814
Location: Birmingham, AL
PostPost subject: Re: YBWC: Active Reparenting    Posted: Thu Apr 19, 2012 7:11 pm Reply to topic Reply with quote
Daniel Shawul wrote:
Quote:

1. 4 elo is tough to measure. Even 30,000 games gives an error bar of +/-4 so that's nowhere near enough. To get to +/- 1, you need something north of 150,000 games. Did you ACTUALLY measure accurately enough to say +4 elo?

I did not do the testing but only predicted it won't help much. Marco here did, and said that he got +4 elo from some thousand blitz games. So it does confirm my suspicion that it won't help much.


I'm not convinced there at all. 1000 games has an error bar FAR wider than 4 elo...

Quote:

Quote:

2. I don't see any measurable idle time in my current search, and saw absolutely none in CB's search. That is not much difference, I don't see how it would add up to +4 elo...

Sure mine has also very small idle time. That is why my nps is almost doubles on 2 processors, but has some losses on more than 8 processors. The OP thought he might gain some on that which is why I replied with my guess that it will not help much in that regard. My guess (as I stated before) is that selection of the better split point among those available may help even if there is 0 reduction of idle time. To avoid confusion , by better split point I mean one which has more work. If you can split near the root, you will have fewer splits which means you avoid the copying of search stack every time we split. Similar to the reason why we limit parallel search above a certain depth.


Note that it also might not be idle time, but memory conflicts. 8 threads can begin to hit a bottleneck getting stuff out of memory. Simple test is to run 8 separate instances of the program at the same time and see what happens to NPS. If it is not 8x one, then memory is the issue, not the parallel algorithm.

If it is 8x, then either the parallel search has some idle time, OR, you might have some significant cache coherency traffic due to poorly laying out variables in memory so that two end up in the same cache block, but are being updated by different cores.
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Subject Author Date/Time
YBWC: Active Reparenting Marco Costalba Tue Apr 10, 2012 5:38 pm
      Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 10, 2012 6:23 pm
            Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 10, 2012 7:11 pm
                  Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 10, 2012 7:54 pm
                        Re: YBWC: Active Reparenting Marco Costalba Tue Apr 10, 2012 8:48 pm
                              Re: YBWC: Active Reparenting Vincent Diepeveen Wed Apr 11, 2012 10:09 am
                                    Re: YBWC: Active Reparenting Robert Hyatt Mon Apr 16, 2012 6:53 pm
                        Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 10, 2012 11:11 pm
                              Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 10, 2012 11:33 pm
                              Re: YBWC: Active Reparenting Robert Hyatt Mon Apr 16, 2012 7:07 pm
                                    Re: YBWC: Active Reparenting Vincent Diepeveen Mon Apr 16, 2012 8:55 pm
                                          Re: YBWC: Active Reparenting Robert Hyatt Tue Apr 17, 2012 2:54 pm
                                                Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 17, 2012 5:42 pm
                                                      Re: YBWC: Active Reparenting Robert Hyatt Tue Apr 17, 2012 8:01 pm
                                                            Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 17, 2012 9:34 pm
                                                                  Re: YBWC: Active Reparenting Robert Hyatt Tue Apr 17, 2012 9:46 pm
                                                                        Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 17, 2012 10:30 pm
                                                                              Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 17, 2012 11:43 pm
                                                                                    Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 1:05 am
                                                                                          Re: YBWC: Active Reparenting Vincent Diepeveen Wed Apr 18, 2012 11:24 am
                                                                                          Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 1:01 pm
                                                                              Re: YBWC: Active Reparenting Robert Hyatt Wed Apr 18, 2012 7:34 pm
                                                                                    Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 11:18 pm
                                                                                          Re: YBWC: Active Reparenting Vincent Diepeveen Thu Apr 19, 2012 7:01 am
                                                                                          Re: YBWC: Active Reparenting Daniel Shawul Thu Apr 19, 2012 12:46 pm
                                                                                          Re: YBWC: Active Reparenting Vincent Diepeveen Thu Apr 19, 2012 2:40 pm
                                                                                          Re: YBWC: Active Reparenting Daniel Shawul Thu Apr 19, 2012 9:32 pm
                                                                                          Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 19, 2012 7:08 pm
                                                                                          Re: YBWC: Active Reparenting Daniel Shawul Thu Apr 19, 2012 9:37 pm
                                                                                          Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 19, 2012 9:48 pm
                                                                                          Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 19, 2012 6:59 pm
                                                                                          Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 19, 2012 5:30 pm
                                                                        Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 17, 2012 11:29 pm
                                                                              Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 12:58 am
                                                                  Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 17, 2012 11:18 pm
                                    Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 17, 2012 5:37 pm
      Re: YBWC: Active Reparenting Álvaro Begué Tue Apr 10, 2012 6:27 pm
            Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 10, 2012 6:44 pm
      Re: YBWC: Active Reparenting Robert Hyatt Tue Apr 10, 2012 9:39 pm
            Re: YBWC: Active Reparenting Marco Costalba Wed Apr 11, 2012 6:06 am
                  Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 12, 2012 1:20 am
                        Re: YBWC: Active Reparenting Vincent Diepeveen Sun Apr 15, 2012 10:04 am
                              Re: YBWC: Active Reparenting Marco Costalba Sun Apr 15, 2012 10:22 am
                                    Re: YBWC: Active Reparenting Vincent Diepeveen Sun Apr 15, 2012 2:39 pm
                                          Re: YBWC: Active Reparenting Marco Costalba Mon Apr 16, 2012 5:29 am
                                                Re: YBWC: Active Reparenting Vincent Diepeveen Mon Apr 16, 2012 5:54 pm
                                                      Re: YBWC: Active Reparenting Marco Costalba Tue Apr 17, 2012 11:30 am
                                                Re: YBWC: Active Reparenting Marco Costalba Wed Apr 18, 2012 6:31 am
      Re: YBWC: Active Reparenting Rein Halbersma Wed Apr 11, 2012 7:23 am
            Re: YBWC: Active Reparenting Vincent Diepeveen Wed Apr 11, 2012 9:07 am
            Re: YBWC: Active Reparenting Vincent Diepeveen Wed Apr 11, 2012 9:31 am
            Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 11, 2012 12:14 pm
                  Re: YBWC: Active Reparenting Vincent Diepeveen Wed Apr 11, 2012 1:54 pm
                  Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 12, 2012 1:28 am
                        Re: YBWC: Active Reparenting Daniel Shawul Tue Apr 17, 2012 5:49 pm
                              Re: YBWC: Active Reparenting Vincent Diepeveen Tue Apr 17, 2012 11:10 pm
                                    Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 12:50 am
                              Re: YBWC: Active Reparenting Robert Hyatt Wed Apr 18, 2012 7:38 pm
                                    Re: YBWC: Active Reparenting Daniel Shawul Wed Apr 18, 2012 11:30 pm
                                          Re: YBWC: Active Reparenting Vincent Diepeveen Thu Apr 19, 2012 7:08 am
                                                Re: YBWC: Active Reparenting Daniel Shawul Thu Apr 19, 2012 12:15 pm
                                                      Re: YBWC: Active Reparenting Vincent Diepeveen Thu Apr 19, 2012 1:53 pm
                                          Re: YBWC: Active Reparenting Robert Hyatt Thu Apr 19, 2012 7:11 pm
      Re: GPUs Srdja Matovic Mon Jun 04, 2012 5:08 pm
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