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Search tuning at very long time control

Browse source 
Many search parameter changes, tuned
(https://tests.stockfishchess.org/tests/view/645e4c67d55cccb2e64220ff)
at ~300k games @ VLTC (120+1.2).

Failed STC:
https://tests.stockfishchess.org/tests/view/6465fcd77968ca827c1410c2
LLR: -2.95 (-2.94,2.94) <0.00,2.00>
Total: 33824 W: 8863 L: 9067 D: 15894
Ptnml(0-2): 89, 3833, 9266, 3641, 83

Neutral LTC:
https://tests.stockfishchess.org/tests/view/646385ce87f6567dd4df4e37
Elo: -0.48 +-1.2 (95%) LOS: 22.2%
Total: 60000 W: 16235 L: 16318 D: 27447
Ptnml(0-2): 27, 5831, 18366, 5750, 26
nElo: -1.08 +-2.8 (95%) PairsRatio: 0.99

Passed VLTC 180+1.8:
https://tests.stockfishchess.org/tests/view/646385f787f6567dd4df4e3e
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 126448 W: 34704 L: 34258 D: 57486
Ptnml(0-2): 9, 10970, 40825, 11406, 14

Passed VLTC SMP 60+0.6 8thread:
https://tests.stockfishchess.org/tests/view/646628de884ce93b65df2ac9
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 59456 W: 16791 L: 16487 D: 26178
Ptnml(0-2): 5, 4473, 20467, 4779, 4

closes https://github.com/official-stockfish/Stockfish/pull/4574

Bench: 3347573
This commit is contained in:
Muzhen Gaming 2023-05-16 21:30:53 +08:00 • committed by Joost VandeVondele
parent 5f7b26aaa0
commit f030a1c592
1 changed files with 47 additions and 47 deletions
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94
src/search.cpp
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@ -64,7 +64,7 @@ namespace {
// Futility margin // Futility margin
Value futility_margin(Depth d, bool improving) { Value futility_margin(Depth d, bool improving) {
return Value(154 * (d - improving)); return Value(148 * (d - improving));
} }
// Reductions lookup table, initialized at startup // Reductions lookup table, initialized at startup
@ -72,7 +72,7 @@ namespace {
Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) { Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) {
int r = Reductions[d] * Reductions[mn]; int r = Reductions[d] * Reductions[mn];
return (r + 1449 - int(delta) * 937 / int(rootDelta)) / 1024 + (!i && r > 941); return (r + 1356 - int(delta) * 983 / int(rootDelta)) / 1024 + (!i && r > 901);
} }
constexpr int futility_move_count(bool improving, Depth depth) { constexpr int futility_move_count(bool improving, Depth depth) {
@ -82,7 +82,7 @@ namespace {
// History and stats update bonus, based on depth // History and stats update bonus, based on depth
int stat_bonus(Depth d) { int stat_bonus(Depth d) {
return std::min(341 * d - 470, 1710); return std::min(337 * d - 497, 1632);
} }
// Add a small random component to draw evaluations to avoid 3-fold blindness // Add a small random component to draw evaluations to avoid 3-fold blindness
@ -162,7 +162,7 @@ namespace {
void Search::init() { void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i) for (int i = 1; i < MAX_MOVES; ++i)
Reductions[i] = int((19.47 + std::log(Threads.size()) / 2) * std::log(i)); Reductions[i] = int((20.89 + std::log(Threads.size()) / 2) * std::log(i));
} }
@ -348,12 +348,12 @@ void Thread::search() {
// Reset aspiration window starting size // Reset aspiration window starting size
Value prev = rootMoves[pvIdx].averageScore; Value prev = rootMoves[pvIdx].averageScore;
delta = Value(10) + int(prev) * prev / 16502; delta = Value(11) + int(prev) * prev / 15368;
alpha = std::max(prev - delta,-VALUE_INFINITE); alpha = std::max(prev - delta,-VALUE_INFINITE);
beta = std::min(prev + delta, VALUE_INFINITE); beta = std::min(prev + delta, VALUE_INFINITE);
// Adjust optimism based on root move's previousScore // Adjust optimism based on root move's previousScore
int opt = 102 * prev / (std::abs(prev) + 147); int opt = 116 * prev / (std::abs(prev) + 143);
optimism[ us] = Value(opt); optimism[ us] = Value(opt);
optimism[~us] = -optimism[us]; optimism[~us] = -optimism[us];
@ -742,7 +742,7 @@ namespace {
// Use static evaluation difference to improve quiet move ordering (~4 Elo) // Use static evaluation difference to improve quiet move ordering (~4 Elo)
if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture) if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
{ {
int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1920, 1920); int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1717, 1717);
thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus;
} }
@ -752,13 +752,13 @@ namespace {
// margin and the improving flag are used in various pruning heuristics. // margin and the improving flag are used in various pruning heuristics.
improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
: (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
: 156; : 163;
improving = improvement > 0; improving = improvement > 0;
// Step 7. Razoring (~1 Elo). // Step 7. Razoring (~1 Elo).
// If eval is really low check with qsearch if it can exceed alpha, if it can't, // If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low. // return a fail low.
if (eval < alpha - 426 - 256 * depth * depth) if (eval < alpha - 467 - 266 * depth * depth)
{ {
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha); value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha) if (value < alpha)
@ -769,18 +769,18 @@ namespace {
// The depth condition is important for mate finding. // The depth condition is important for mate finding.
if ( !ss->ttPv if ( !ss->ttPv
&& depth < 9 && depth < 9
&& eval - futility_margin(depth, improving) - (ss-1)->statScore / 280 >= beta && eval - futility_margin(depth, improving) - (ss-1)->statScore / 306 >= beta
&& eval >= beta && eval >= beta
&& eval < 25128) // larger than VALUE_KNOWN_WIN, but smaller than TB wins && eval < 22761) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
return eval; return eval;
// Step 9. Null move search with verification search (~35 Elo) // Step 9. Null move search with verification search (~35 Elo)
if ( !PvNode if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL && (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 18755 && (ss-1)->statScore < 18404
&& eval >= beta && eval >= beta
&& eval >= ss->staticEval && eval >= ss->staticEval
&& ss->staticEval >= beta - 20 * depth - improvement / 13 + 253 && ss->staticEval >= beta - 19 * depth - improvement / 13 + 257
&& !excludedMove && !excludedMove
&& pos.non_pawn_material(us) && pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly)) && (ss->ply >= thisThread->nmpMinPly))
@ -823,13 +823,13 @@ namespace {
} }
} }
probCutBeta = beta + 186 - 54 * improving; probCutBeta = beta + 174 - 60 * improving;
// Step 10. ProbCut (~10 Elo) // Step 10. ProbCut (~10 Elo)
// If we have a good enough capture (or queen promotion) and a reduced search returns a value // If we have a good enough capture (or queen promotion) and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move. // much above beta, we can (almost) safely prune the previous move.
if ( !PvNode if ( !PvNode
&& depth > 4 && depth > 3
&& abs(beta) < VALUE_TB_WIN_IN_MAX_PLY && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
// if value from transposition table is lower than probCutBeta, don't attempt probCut // if value from transposition table is lower than probCutBeta, don't attempt probCut
// there and in further interactions with transposition table cutoff depth is set to depth - 3 // there and in further interactions with transposition table cutoff depth is set to depth - 3
@ -887,20 +887,20 @@ namespace {
return qsearch<PV>(pos, ss, alpha, beta); return qsearch<PV>(pos, ss, alpha, beta);
if ( cutNode if ( cutNode
&& depth >= 7 && depth >= 8
&& !ttMove) && !ttMove)
depth -= 2; depth -= 2;
moves_loop: // When in check, search starts here moves_loop: // When in check, search starts here
// Step 12. A small Probcut idea, when we are in check (~4 Elo) // Step 12. A small Probcut idea, when we are in check (~4 Elo)
probCutBeta = beta + 391; probCutBeta = beta + 430;
if ( ss->inCheck if ( ss->inCheck
&& !PvNode && !PvNode
&& depth >= 2 && depth >= 2
&& ttCapture && ttCapture
&& (tte->bound() & BOUND_LOWER) && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 && tte->depth() >= depth - 4
&& ttValue >= probCutBeta && ttValue >= probCutBeta
&& abs(ttValue) <= VALUE_KNOWN_WIN && abs(ttValue) <= VALUE_KNOWN_WIN
&& abs(beta) <= VALUE_KNOWN_WIN) && abs(beta) <= VALUE_KNOWN_WIN)
@ -986,15 +986,15 @@ moves_loop: // When in check, search starts here
{ {
// Futility pruning for captures (~2 Elo) // Futility pruning for captures (~2 Elo)
if ( !givesCheck if ( !givesCheck
&& lmrDepth < 6 && lmrDepth < 7
&& !ss->inCheck && !ss->inCheck
&& ss->staticEval + 182 + 230 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] && ss->staticEval + 207 + 223 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))]
+ captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 7 < alpha) + captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] * 1078 / 7000 < alpha)
continue; continue;
Bitboard occupied; Bitboard occupied;
// SEE based pruning (~11 Elo) // SEE based pruning (~11 Elo)
if (!pos.see_ge(move, occupied, Value(-206) * depth)) if (!pos.see_ge(move, occupied, Value(-205) * depth))
{ {
if (depth < 2 - capture) if (depth < 2 - capture)
continue; continue;
@ -1022,24 +1022,24 @@ moves_loop: // When in check, search starts here
// Continuation history based pruning (~2 Elo) // Continuation history based pruning (~2 Elo)
if ( lmrDepth < 5 if ( lmrDepth < 5
&& history < -4405 * (depth - 1)) && history < -3792 * (depth - 1))
continue; continue;
history += 2 * thisThread->mainHistory[us][from_to(move)]; history += 2 * thisThread->mainHistory[us][from_to(move)];
lmrDepth += history / 7278; lmrDepth += history / 7019;
lmrDepth = std::max(lmrDepth, -2); lmrDepth = std::max(lmrDepth, -2);
// Futility pruning: parent node (~13 Elo) // Futility pruning: parent node (~13 Elo)
if ( !ss->inCheck if ( !ss->inCheck
&& lmrDepth < 13 && lmrDepth < 12
&& ss->staticEval + 103 + 138 * lmrDepth <= alpha) && ss->staticEval + 111 + 136 * lmrDepth <= alpha)
continue; continue;
lmrDepth = std::max(lmrDepth, 0); lmrDepth = std::max(lmrDepth, 0);
// Prune moves with negative SEE (~4 Elo) // Prune moves with negative SEE (~4 Elo)
if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 16 * lmrDepth))) if (!pos.see_ge(move, Value(-27 * lmrDepth * lmrDepth - 33 * lmrDepth / 2)))
continue; continue;
} }
} }
@ -1054,7 +1054,7 @@ moves_loop: // When in check, search starts here
// a reduced search on all the other moves but the ttMove and if the // a reduced search on all the other moves but the ttMove and if the
// result is lower than ttValue minus a margin, then we will extend the ttMove. // result is lower than ttValue minus a margin, then we will extend the ttMove.
if ( !rootNode if ( !rootNode
&& depth >= 4 - (thisThread->completedDepth > 21) + 2 * (PvNode && tte->is_pv()) && depth >= 4 - (thisThread->completedDepth > 22) + 2 * (PvNode && tte->is_pv())
&& move == ttMove && move == ttMove
&& !excludedMove // Avoid recursive singular search && !excludedMove // Avoid recursive singular search
/* && ttValue != VALUE_NONE Already implicit in the next condition */ /* && ttValue != VALUE_NONE Already implicit in the next condition */
@ -1062,7 +1062,7 @@ moves_loop: // When in check, search starts here
&& (tte->bound() & BOUND_LOWER) && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3) && tte->depth() >= depth - 3)
{ {
Value singularBeta = ttValue - (3 + 2 * (ss->ttPv && !PvNode)) * depth / 2; Value singularBeta = ttValue - (99 + 65 * (ss->ttPv && !PvNode)) * depth / 64;
Depth singularDepth = (depth - 1) / 2; Depth singularDepth = (depth - 1) / 2;
ss->excludedMove = move; ss->excludedMove = move;
@ -1076,8 +1076,8 @@ moves_loop: // When in check, search starts here
// Avoid search explosion by limiting the number of double extensions // Avoid search explosion by limiting the number of double extensions
if ( !PvNode if ( !PvNode
&& value < singularBeta - 25 && value < singularBeta - 22
&& ss->doubleExtensions <= 10) && ss->doubleExtensions <= 11)
{ {
extension = 2; extension = 2;
depth += depth < 13; depth += depth < 13;
@ -1107,15 +1107,15 @@ moves_loop: // When in check, search starts here
// Check extensions (~1 Elo) // Check extensions (~1 Elo)
else if ( givesCheck else if ( givesCheck
&& depth > 10 && depth > 9
&& abs(ss->staticEval) > 88) && abs(ss->staticEval) > 87)
extension = 1; extension = 1;
// Quiet ttMove extensions (~1 Elo) // Quiet ttMove extensions (~1 Elo)
else if ( PvNode else if ( PvNode
&& move == ttMove && move == ttMove
&& move == ss->killers[0] && move == ss->killers[0]
&& (*contHist[0])[movedPiece][to_sq(move)] >= 5705) && (*contHist[0])[movedPiece][to_sq(move)] >= 5480)
extension = 1; extension = 1;
} }
@ -1144,7 +1144,7 @@ moves_loop: // When in check, search starts here
r -= cutNode && tte->depth() >= depth + 3 ? 3 : 2; r -= cutNode && tte->depth() >= depth + 3 ? 3 : 2;
// Decrease reduction if opponent's move count is high (~1 Elo) // Decrease reduction if opponent's move count is high (~1 Elo)
if ((ss-1)->moveCount > 7) if ((ss-1)->moveCount > 8)
r--; r--;
// Increase reduction for cut nodes (~3 Elo) // Increase reduction for cut nodes (~3 Elo)
@ -1157,7 +1157,7 @@ moves_loop: // When in check, search starts here
// Decrease reduction for PvNodes based on depth (~2 Elo) // Decrease reduction for PvNodes based on depth (~2 Elo)
if (PvNode) if (PvNode)
r -= 1 + 12 / (3 + depth); r -= 1 + 11 / (3 + depth);
// Decrease reduction if ttMove has been singularly extended (~1 Elo) // Decrease reduction if ttMove has been singularly extended (~1 Elo)
if (singularQuietLMR) if (singularQuietLMR)
@ -1174,10 +1174,10 @@ moves_loop: // When in check, search starts here
+ (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)]
- 4082; - 3755;
// Decrease/increase reduction for moves with a good/bad history (~25 Elo) // Decrease/increase reduction for moves with a good/bad history (~25 Elo)
r -= ss->statScore / (11079 + 4626 * (depth > 6 && depth < 19)); r -= ss->statScore / (10445 + 4762 * (depth > 6 && depth < 21));
// Step 17. Late moves reduction / extension (LMR, ~117 Elo) // Step 17. Late moves reduction / extension (LMR, ~117 Elo)
// We use various heuristics for the sons of a node after the first son has // We use various heuristics for the sons of a node after the first son has
@ -1201,8 +1201,8 @@ moves_loop: // When in check, search starts here
{ {
// Adjust full depth search based on LMR results - if result // Adjust full depth search based on LMR results - if result
// was good enough search deeper, if it was bad enough search shallower // was good enough search deeper, if it was bad enough search shallower
const bool doDeeperSearch = value > (bestValue + 68 + 12 * (newDepth - d)); const bool doDeeperSearch = value > (bestValue + 63 + 11 * (newDepth - d));
const bool doEvenDeeperSearch = value > alpha + 588 && ss->doubleExtensions <= 5; const bool doEvenDeeperSearch = value > alpha + 662 && ss->doubleExtensions <= 6;
const bool doShallowerSearch = value < bestValue + newDepth; const bool doShallowerSearch = value < bestValue + newDepth;
ss->doubleExtensions = ss->doubleExtensions + doEvenDeeperSearch; ss->doubleExtensions = ss->doubleExtensions + doEvenDeeperSearch;
@ -1227,7 +1227,7 @@ moves_loop: // When in check, search starts here
if (!ttMove && cutNode) if (!ttMove && cutNode)
r += 2; r += 2;
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth - (r > 4), !cutNode); value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth - (r > 3), !cutNode);
} }
// For PV nodes only, do a full PV search on the first move or after a fail // For PV nodes only, do a full PV search on the first move or after a fail
@ -1320,8 +1320,8 @@ moves_loop: // When in check, search starts here
{ {
// Reduce other moves if we have found at least one score improvement (~1 Elo) // Reduce other moves if we have found at least one score improvement (~1 Elo)
if ( depth > 1 if ( depth > 1
&& beta < 12535 && beta < 14001
&& value > -12535) && value > -12754)
depth -= 1; depth -= 1;
assert(depth > 0); assert(depth > 0);
@ -1370,7 +1370,7 @@ moves_loop: // When in check, search starts here
// Bonus for prior countermove that caused the fail low // Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE) else if (!priorCapture && prevSq != SQ_NONE)
{ {
int bonus = (depth > 5) + (PvNode || cutNode) + (bestValue < alpha - 97 * depth) + ((ss-1)->moveCount > 10); int bonus = (depth > 5) + (PvNode || cutNode) + (bestValue < alpha - 100 * depth) + ((ss-1)->moveCount > 11);
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * bonus); update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * bonus);
} }
@ -1499,7 +1499,7 @@ moves_loop: // When in check, search starts here
if (PvNode && bestValue > alpha) if (PvNode && bestValue > alpha)
alpha = bestValue; alpha = bestValue;
futilityBase = bestValue + 168; futilityBase = bestValue + 190;
} }
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@ -1572,7 +1572,7 @@ moves_loop: // When in check, search starts here
continue; continue;
// Do not search moves with bad enough SEE values (~5 Elo) // Do not search moves with bad enough SEE values (~5 Elo)
if (!pos.see_ge(move, Value(-110))) if (!pos.see_ge(move, Value(-94)))
continue; continue;
} }
@ -1705,7 +1705,7 @@ moves_loop: // When in check, search starts here
if (!pos.capture_stage(bestMove)) if (!pos.capture_stage(bestMove))
{ {
int bonus2 = bestValue > beta + 153 ? bonus1 // larger bonus int bonus2 = bestValue > beta + 143 ? bonus1 // larger bonus
: stat_bonus(depth); // smaller bonus : stat_bonus(depth); // smaller bonus
// Increase stats for the best move in case it was a quiet move // Increase stats for the best move in case it was a quiet move