X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=31e8b0b661f46392453d097c39e137ba52bead57;hb=3627348e2b4633604a878b0e5397acb6218a6afc;hp=458f149077e9dc30ffa8cfe30517884b36ee3ca8;hpb=05cf45f2d137600387d5e560e22a464a84ad7b0d;p=stockfish

diff --git a/src/search.cpp b/src/search.cpp
index 458f1490..31e8b0b6 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -132,34 +132,18 @@ namespace {
     Move pv[3];
   };
 
-  // Set of rows with half bits set to 1 and half to 0. It is used to allocate
-  // the search depths across the threads.
-  typedef std::vector<int> Row;
-
-  const Row HalfDensity[] = {
-    {0, 1},
-    {1, 0},
-    {0, 0, 1, 1},
-    {0, 1, 1, 0},
-    {1, 1, 0, 0},
-    {1, 0, 0, 1},
-    {0, 0, 0, 1, 1, 1},
-    {0, 0, 1, 1, 1, 0},
-    {0, 1, 1, 1, 0, 0},
-    {1, 1, 1, 0, 0, 0},
-    {1, 1, 0, 0, 0, 1},
-    {1, 0, 0, 0, 1, 1},
-    {0, 0, 0, 0, 1, 1, 1, 1},
-    {0, 0, 0, 1, 1, 1, 1, 0},
-    {0, 0, 1, 1, 1, 1, 0 ,0},
-    {0, 1, 1, 1, 1, 0, 0 ,0},
-    {1, 1, 1, 1, 0, 0, 0 ,0},
-    {1, 1, 1, 0, 0, 0, 0 ,1},
-    {1, 1, 0, 0, 0, 0, 1 ,1},
-    {1, 0, 0, 0, 0, 1, 1 ,1},
-  };
+  // skip half of the plies in blocks depending on the helper thread idx.
+  bool skip_ply(int idx, int ply) {
+
+    idx = (idx - 1) % 20 + 1; // cycle after 20 threads.
 
-  const size_t HalfDensitySize = std::extent<decltype(HalfDensity)>::value;
+    // number of successive plies to skip, depending on idx.
+    int ones = 1;
+    while (ones * (ones + 1) < idx)
+        ones++;
+
+    return ((ply + idx - 1) / ones - ones) % 2 == 0;
+  }
 
   EasyMoveManager EasyMove;
   Value DrawValue[COLOR_NB];
@@ -379,14 +363,9 @@ void Thread::search() {
          && !Signals.stop
          && (!Limits.depth || Threads.main()->rootDepth / ONE_PLY <= Limits.depth))
   {
-      // Set up the new depths for the helper threads skipping on average every
-      // 2nd ply (using a half-density matrix).
-      if (!mainThread)
-      {
-          const Row& row = HalfDensity[(idx - 1) % HalfDensitySize];
-          if (row[(rootDepth / ONE_PLY + rootPos.game_ply()) % row.size()])
-             continue;
-      }
+      // skip plies for helper threads
+      if (idx && skip_ply(idx, rootDepth / ONE_PLY + rootPos.game_ply()))
+          continue;
 
       // Age out PV variability metric
       if (mainThread)
@@ -923,7 +902,7 @@ moves_loop: // When in check search starts from here
       {
           if (   !captureOrPromotion
               && !givesCheck
-              && !pos.advanced_pawn_push(move))
+              && (!pos.advanced_pawn_push(move) || pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 5000))
           {
               // Move count based pruning
               if (moveCountPruning)