X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=142afd90e56ca63e1b79691f27b6c51a5a19f966;hp=d087cc38f77e2cad94feb67940ccc26c37f06189;hb=0424273d0b20ae7ad65143b530b2db8b94de0338;hpb=ca7d4e9ac7b5ca74be8aa807fbdf139b2a0860ab diff --git a/src/tt.h b/src/tt.h index d087cc38..142afd90 100644 --- a/src/tt.h +++ b/src/tt.h @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -57,24 +57,22 @@ private: }; -/// A TranspositionTable consists of a power of 2 number of clusters and each -/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry -/// contains information of exactly one position. The size of a cluster should -/// divide the size of a cache line size, to ensure that clusters never cross -/// cache lines. This ensures best cache performance, as the cacheline is -/// prefetched, as soon as possible. +/// A TranspositionTable is an array of Cluster, of size clusterCount. Each +/// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry +/// contains information on exactly one position. The size of a Cluster should +/// divide the size of a cache line for best performance, +/// as the cacheline is prefetched when possible. class TranspositionTable { - static constexpr int CacheLineSize = 64; static constexpr int ClusterSize = 3; struct Cluster { TTEntry entry[ClusterSize]; - char padding[2]; // Align to a divisor of the cache line size + char padding[2]; // Pad to 32 bytes }; - static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect"); + static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size"); public: ~TranspositionTable() { free(mem); }