Dev Builds » 20190701-1207

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NCM plays each Stockfish dev build 20,000 times against Stockfish 14. This yields an approximate Elo difference and establishes confidence in the strength of the dev builds.


Host Duration Avg Base NPS Games WLD Standard Elo Ptnml(0-2) Gamepair Elo

Test Detail

ID Host Base NPS Games WLD Standard Elo Ptnml(0-2) Gamepair Elo CLI PGN


Commit ID 217840a6a5a40b516cab59a450a9f36352997240
Author Joost VandeVondele
Date 2019-07-01 12:07:23 UTC
Introduce coordination between searching threads (#2204) this patch improves threading performance by introducing some coordination between threads. The observation is that threading is an area where a lot of Elo can potentially be gained: At STC, 8 threads gain roughly 320 Elo, vs sequential at the same time, however, loses 66 Elo against a single thread with 8x more time. This 66 Elo should be partially recoverable with improved threading. To improve threading, this patch introduces some LMR at nodes that are already being searched by other threads. This requires some coordination between threads, avoiding however synchronisation. To do so, threads leave a trail of breadcrumbs to mark the nodes they are searching. These breadcrumbs are stored in a small hash table, which is only probed at low plies (currently ply < 8). A couple of variants of this patch passed both STC and LTC threaded tests. I picked the simpler, more robust version. I expect that further tests can find further improvements. STC (5+0.05 @ 8 threads): LLR: 2.95 (-2.94,2.94) [0.50,4.50] Total: 26209 W: 5359 L: 5079 D: 15771 LTC (20+0.2 @ 8 threads): LLR: 2.96 (-2.94,2.94) [0.00,3.50] Total: 34832 W: 5650 L: 5382 D: 23800 other passed/tested variants: For the sequential code there is no change in bench, and an earlier version of this patch passed a non-regression test. STC (10+0.1 @ 1 thread) LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 10471 W: 2364 L: 2220 D: 5887 passed the additional non-regression tests at 2 and 4 threads 20+0.2 TC. The code was rebased on master prior to testing. 2 threads: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 218863 W: 40927 L: 41153 D: 136783 4threads: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 16839 W: 3017 L: 2889 D: 10933 No functional change.
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