Document variables with heavy SMP read access

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index d8c0c7dd3f4ad89db231456a5fe3c82c3324fc35..a6e2c3410d504bf3d9f3de04abb0ba3249b59e65 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -128,17 +128,13 @@ namespace {
   };
 
 
   };
 
 

-  /// Constants and variables initialized from UCI options
+  /// Constants

 
 

-  // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV
-  // nodes
-  int LMRPVMoves, LMRNonPVMoves;
-
-  // Depth limit for use of dynamic threat detection
-  Depth ThreatDepth;
+  // Search depth at iteration 1
+  const Depth InitialDepth = OnePly /*+ OnePly/2*/;

 
   // Depth limit for selective search
 
   // Depth limit for selective search

-  const Depth SelectiveDepth = 7*OnePly;
+  const Depth SelectiveDepth = 7 * OnePly;

 
   // Use internal iterative deepening?
   const bool UseIIDAtPVNodes = true;
 
   // Use internal iterative deepening?
   const bool UseIIDAtPVNodes = true;


@@ -174,25 +170,31 @@ namespace {
   const bool PruneDefendingMoves = false;
   const bool PruneBlockingMoves = false;
 
   const bool PruneDefendingMoves = false;
   const bool PruneBlockingMoves = false;
 

-  // Use futility pruning?
-  bool UseQSearchFutilityPruning, UseFutilityPruning;
-

   // Margins for futility pruning in the quiescence search, and at frontier
   // and near frontier nodes
   const Value FutilityMarginQS = Value(0x80);
 
   // Margins for futility pruning in the quiescence search, and at frontier
   // and near frontier nodes
   const Value FutilityMarginQS = Value(0x80);
 

-   // Remaining depth:                  1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
-   const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),
+  // Remaining depth:                  1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
+  const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),

   //                                   4 ply         4.5 ply       5 ply         5.5 ply       6 ply         6.5 ply
                                       Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) };
   //                                   4 ply         4.5 ply       5 ply         5.5 ply       6 ply         6.5 ply
                                       Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) };

-   // Razoring
-   const Depth RazorDepth = 4*OnePly;
+  // Razoring
+  const Depth RazorDepth = 4*OnePly;

 
   // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
   const Value RazorMargins[6]     = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) };
 
   // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
 
   // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
   const Value RazorMargins[6]     = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) };
 
   // Remaining depth:                 1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply

-   const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
+  const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
+
+
+  /// Variables initialized from UCI options
+
+  // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
+  int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter
+
+  // Depth limit for use of dynamic threat detection
+  Depth ThreatDepth; // heavy SMP read access

 
   // Last seconds noise filtering (LSN)
   bool UseLSNFiltering;
 
   // Last seconds noise filtering (LSN)
   bool UseLSNFiltering;


@@ -201,21 +203,15 @@ namespace {
   Value LSNValue;
 
   // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
   Value LSNValue;
 
   // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.

+  // There is heavy SMP read access on these arrays

   Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2];
   Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
 
   Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2];
   Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
 

-  // Search depth at iteration 1
-  const Depth InitialDepth = OnePly /*+ OnePly/2*/;
-
-  // Node counters
-  int NodesSincePoll;
-  int NodesBetweenPolls = 30000;
-

   // Iteration counters
   int Iteration;
   // Iteration counters
   int Iteration;

-  BetaCounterType BetaCounter;
+  BetaCounterType BetaCounter; // has per-thread internal data

 
 

-  // Scores and number of times the best move changed for each iteration:
+  // Scores and number of times the best move changed for each iteration

   IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
   int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
 
   IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
   int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
 


@@ -231,7 +227,7 @@ namespace {
   bool InfiniteSearch;
   bool PonderSearch;
   bool StopOnPonderhit;
   bool InfiniteSearch;
   bool PonderSearch;
   bool StopOnPonderhit;

-  bool AbortSearch;
+  bool AbortSearch; // heavy SMP read access

   bool Quit;
   bool FailHigh;
   bool FailLow;
   bool Quit;
   bool FailHigh;
   bool FailLow;


@@ -263,6 +259,11 @@ namespace {
   HANDLE SitIdleEvent[THREAD_MAX];
 #endif
 
   HANDLE SitIdleEvent[THREAD_MAX];
 #endif
 

+  // Node counters, used only by thread[0] but try to keep in different
+  // cache lines (64 bytes each) from the heavy SMP read accessed variables.
+  int NodesSincePoll;
+  int NodesBetweenPolls = 30000;
+

 
   /// Functions
 
 
   /// Functions
 


@@ -432,9 +433,6 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
 
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
 

-  UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
-  UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
-

   UseLSNFiltering = get_option_value_bool("LSN filtering");
   LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
   LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
   UseLSNFiltering = get_option_value_bool("LSN filtering");
   LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
   LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));


@@ -1324,8 +1322,7 @@ namespace {
     Value value, bestValue = -VALUE_INFINITE;
     Bitboard dcCandidates = mp.discovered_check_candidates();
     Value futilityValue = VALUE_NONE;
     Value value, bestValue = -VALUE_INFINITE;
     Bitboard dcCandidates = mp.discovered_check_candidates();
     Value futilityValue = VALUE_NONE;

-    bool useFutilityPruning =   UseFutilityPruning
-                             && depth < SelectiveDepth
+    bool useFutilityPruning =   depth < SelectiveDepth

                              && !isCheck;
 
     // Loop through all legal moves until no moves remain or a beta cutoff
                              && !isCheck;
 
     // Loop through all legal moves until no moves remain or a beta cutoff


@@ -1556,8 +1553,7 @@ namespace {
       ss[ply].currentMove = move;
 
       // Futility pruning
       ss[ply].currentMove = move;
 
       // Futility pruning

-      if (    UseQSearchFutilityPruning
-          &&  enoughMaterial
+      if (   enoughMaterial

           && !isCheck
           && !pvNode
           && !move_promotion(move)
           && !isCheck
           && !pvNode
           && !move_promotion(move)


@@ -1651,8 +1647,7 @@ namespace {
     Value value;
     Move move;
     bool isCheck = pos.is_check();
     Value value;
     Move move;
     bool isCheck = pos.is_check();

-    bool useFutilityPruning =    UseFutilityPruning
-                              && sp->depth < SelectiveDepth
+    bool useFutilityPruning =     sp->depth < SelectiveDepth

                               && !isCheck;
 
     while (    sp->bestValue < sp->beta
                               && !isCheck;
 
     while (    sp->bestValue < sp->beta