Time management improvements

1. Tune time management parameters.
2. Scale the optimum time and maximum time parameters based on the amount of
   time left, using a logarithmic scale.

Many acknowledgements to @FauziAkram for tuning the parameters and for the
original idea (see
https://tests.stockfishchess.org/tests/view/652f0356de6d262d08d333c5).

STC: https://tests.stockfishchess.org/tests/view/6533938fde6d262d08d39e4d
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 44320 W: 11301 L: 10982 D: 22037
Ptnml(0-2): 146, 4810, 11920, 5147, 137

LTC: https://tests.stockfishchess.org/tests/view/653477e4de6d262d08d3ae06
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 146442 W: 37338 L: 36811 D: 72293
Ptnml(0-2): 60, 14975, 42645, 15460, 81

Verification runs:
3+0.03: https://tests.stockfishchess.org/tests/view/65364e7ef127f3553505178a
10+0: https://tests.stockfishchess.org/tests/view/65364e9ff127f3553505178f
180+1.8: https://tests.stockfishchess.org/tests/view/65364ec3f127f35535051794

closes https://github.com/official-stockfish/Stockfish/pull/4843

No functional change.

Co-Authored-By: FauziAkram <11150271+FauziAkram@users.noreply.github.com>

diff --git a/src/search.cpp b/src/search.cpp
index 933cd154e0d1c43eaa6ed6e68232214d533839f0..d5416e407599d03e9c46b56b64297f6de5be57c7 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -467,15 +467,15 @@ void Thread::search() {
         // Do we have time for the next iteration? Can we stop searching now?
         if (Limits.use_time_management() && !Threads.stop && !mainThread->stopOnPonderhit)
         {
-            double fallingEval = (69 + 13 * (mainThread->bestPreviousAverageScore - bestValue)
+            double fallingEval = (66 + 14 * (mainThread->bestPreviousAverageScore - bestValue)
                                   + 6 * (mainThread->iterValue[iterIdx] - bestValue))
-                               / 619.6;
+                               / 583.0;
             fallingEval = std::clamp(fallingEval, 0.5, 1.5);
 
             // If the bestMove is stable over several iterations, reduce time accordingly
-            timeReduction    = lastBestMoveDepth + 8 < completedDepth ? 1.57 : 0.65;
-            double reduction = (1.4 + mainThread->previousTimeReduction) / (2.08 * timeReduction);
-            double bestMoveInstability = 1 + 1.8 * totBestMoveChanges / Threads.size();
+            timeReduction    = lastBestMoveDepth + 8 < completedDepth ? 1.56 : 0.69;
+            double reduction = (1.4 + mainThread->previousTimeReduction) / (2.03 * timeReduction);
+            double bestMoveInstability = 1 + 1.79 * totBestMoveChanges / Threads.size();
 
             double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability;
 

diff --git a/src/timeman.cpp b/src/timeman.cpp
index 7e77a4add053d6e656558c5d90e1893b517845f6..1253d434672709094cb7496dea0b37f08dc02fb5 100644 (file)
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -72,7 +72,11 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
                                                   - moveOverhead * (2 + mtg));
 
     // Use extra time with larger increments
-    double optExtra = std::clamp(1.0 + 12.0 * limits.inc[us] / limits.time[us], 1.0, 1.12);
+    double optExtra = std::clamp(1.0 + 12.5 * limits.inc[us] / limits.time[us], 1.0, 1.12);
+
+    // Calculate time constants based on current time left.
+    double optConstant = std::min(0.00335 + 0.0003 * std::log10(limits.time[us] / 1000.0), 0.0048);
+    double maxConstant = std::max(3.6 + 3.0 * std::log10(limits.time[us] / 1000.0), 2.7);
 
     // A user may scale time usage by setting UCI option "Slow Mover"
     // Default is 100 and changing this value will probably lose elo.
@@ -83,10 +87,10 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
     // game time for the current move, so also cap to 20% of available game time.
     if (limits.movestogo == 0)
     {
-        optScale = std::min(0.0120 + std::pow(ply + 3.0, 0.45) * 0.0039,
+        optScale = std::min(0.0120 + std::pow(ply + 3.3, 0.44) * optConstant,
                             0.2 * limits.time[us] / double(timeLeft))
                  * optExtra;
-        maxScale = std::min(7.0, 4.0 + ply / 12.0);
+        maxScale = std::min(6.8, maxConstant + ply / 12.2);
     }
 
     // x moves in y seconds (+ z increment)
@@ -96,10 +100,10 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
         maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
     }
 
-    // Never use more than 80% of the available time for this move
+    // Limit the maximum possible time for this move
     optimumTime = TimePoint(optScale * timeLeft);
     maximumTime =
-      TimePoint(std::min(0.8 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
+      TimePoint(std::min(0.84 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
 
     if (Options["Ponder"])
         optimumTime += optimumTime / 4;