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Tune search at very long time control

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This patch is a result of tuning done by user @candirufish after 150k games.

Since the tuned values were really interesting and touched heuristics
that are known for their non-linear scaling I decided to run limited
games LTC match, even if the STC test was really bad (which was expected).
After seeing the results of the LTC match, I also run a VLTC (very long
time control) SPRTtest, which passed.

The main difference is in extensions: this patch allows much more
singular/double extensions, both in terms of allowing them at lower
depths and with lesser margins.

Failed STC:
https://tests.stockfishchess.org/tests/view/620d66643ec80158c0cd3b46
LLR: -2.94 (-2.94,2.94) <0.00,2.50>
Total: 4968 W: 1194 L: 1398 D: 2376
Ptnml(0-2): 47, 633, 1294, 497, 13

Performed well at LTC in a fixed-length match:
https://tests.stockfishchess.org/tests/view/620d66823ec80158c0cd3b4a
ELO: 3.36 +-1.8 (95%) LOS: 100.0%
Total: 30000 W: 7966 L: 7676 D: 14358
Ptnml(0-2): 36, 2936, 8755, 3248, 25

Passed VLTC SPRT test:
https://tests.stockfishchess.org/tests/view/620da11a26f5b17ec884f939
LLR: 2.96 (-2.94,2.94) <0.50,3.00>
Total: 4400 W: 1326 L: 1127 D: 1947
Ptnml(0-2): 13, 309, 1348, 526, 4

closes https://github.com/official-stockfish/Stockfish/pull/3937

Bench: 6318903
This commit is contained in:
Michael Chaly 2022-02-17 10:54:07 +03:00 • committed by Stéphane Nicolet
parent 3ec6e1d245
commit 84b1940fca
1 changed files with 44 additions and 44 deletions
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88
src/search.cpp
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@ -63,7 +63,7 @@ namespace {
// Futility margin // Futility margin
Value futility_margin(Depth d, bool improving) { Value futility_margin(Depth d, bool improving) {
return Value(147 * (d - improving)); return Value(168 * (d - improving));
} }
// Reductions lookup table, initialized at startup // Reductions lookup table, initialized at startup
@ -71,7 +71,7 @@ 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 + 1627 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 992); return (r + 1463 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 1010);
} }
constexpr int futility_move_count(bool improving, Depth depth) { constexpr int futility_move_count(bool improving, Depth depth) {
@ -80,7 +80,7 @@ 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((8 * d + 281) * d - 241 , 1949); return std::min((9 * d + 270) * d - 311 , 2145);
} }
// 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
@ -157,7 +157,7 @@ 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((21.14 + std::log(Threads.size()) / 2) * std::log(i)); Reductions[i] = int((20.81 + std::log(Threads.size()) / 2) * std::log(i));
} }
@ -303,10 +303,10 @@ void Thread::search() {
multiPV = std::min(multiPV, rootMoves.size()); multiPV = std::min(multiPV, rootMoves.size());
complexityAverage.set(211, 1); complexityAverage.set(202, 1);
trend = SCORE_ZERO; trend = SCORE_ZERO;
optimism[ us] = Value(33); optimism[ us] = Value(39);
optimism[~us] = -optimism[us]; optimism[~us] = -optimism[us];
int searchAgainCounter = 0; int searchAgainCounter = 0;
@ -349,16 +349,16 @@ void Thread::search() {
if (rootDepth >= 4) if (rootDepth >= 4)
{ {
Value prev = rootMoves[pvIdx].averageScore; Value prev = rootMoves[pvIdx].averageScore;
delta = Value(19) + int(prev) * prev / 18321; delta = Value(16) + int(prev) * prev / 19178;
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 trend and optimism based on root move's previousScore // Adjust trend and optimism based on root move's previousScore
int tr = sigmoid(prev, 4, 11, 92, 119, 1); int tr = sigmoid(prev, 3, 8, 90, 125, 1);
trend = (us == WHITE ? make_score(tr, tr / 2) trend = (us == WHITE ? make_score(tr, tr / 2)
: -make_score(tr, tr / 2)); : -make_score(tr, tr / 2));
int opt = sigmoid(prev, 9, 18, 115, 12250, 187); int opt = sigmoid(prev, 8, 17, 144, 13966, 183);
optimism[ us] = Value(opt); optimism[ us] = Value(opt);
optimism[~us] = -optimism[us]; optimism[~us] = -optimism[us];
} }
@ -459,17 +459,17 @@ void Thread::search() {
&& !Threads.stop && !Threads.stop
&& !mainThread->stopOnPonderhit) && !mainThread->stopOnPonderhit)
{ {
double fallingEval = (66 + 12 * (mainThread->bestPreviousAverageScore - bestValue) double fallingEval = (69 + 12 * (mainThread->bestPreviousAverageScore - bestValue)
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 809.70; + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 781.4;
fallingEval = std::clamp(fallingEval, 0.5, 1.5); fallingEval = std::clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly // If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = lastBestMoveDepth + 8 < completedDepth ? 1.73 : 0.94; timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.63 : 0.73;
double reduction = (1.66 + mainThread->previousTimeReduction) / (2.35 * timeReduction); double reduction = (1.56 + mainThread->previousTimeReduction) / (2.20 * timeReduction);
double bestMoveInstability = 1.073 + std::max(1.0, 2.25 - 9.9 / rootDepth) double bestMoveInstability = 1.073 + std::max(1.0, 2.25 - 9.9 / rootDepth)
* totBestMoveChanges / Threads.size(); * totBestMoveChanges / Threads.size();
int complexity = mainThread->complexityAverage.value(); int complexity = mainThread->complexityAverage.value();
double complexPosition = std::clamp(1.0 + (complexity - 293) / 1525.0, 0.5, 1.5); double complexPosition = std::clamp(1.0 + (complexity - 326) / 1618.1, 0.5, 1.5);
double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * complexPosition; double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * complexPosition;
@ -490,7 +490,7 @@ void Thread::search() {
} }
else if ( Threads.increaseDepth else if ( Threads.increaseDepth
&& !mainThread->ponder && !mainThread->ponder
&& Time.elapsed() > totalTime * 0.49) && Time.elapsed() > totalTime * 0.43)
Threads.increaseDepth = false; Threads.increaseDepth = false;
else else
Threads.increaseDepth = true; Threads.increaseDepth = true;
@ -766,7 +766,7 @@ 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
: 184; : 175;
improving = improvement > 0; improving = improvement > 0;
complexity = abs(ss->staticEval - (us == WHITE ? eg_value(pos.psq_score()) : -eg_value(pos.psq_score()))); complexity = abs(ss->staticEval - (us == WHITE ? eg_value(pos.psq_score()) : -eg_value(pos.psq_score())));
@ -777,8 +777,8 @@ namespace {
// 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 ( !PvNode if ( !PvNode
&& depth <= 6 && depth <= 7
&& eval < alpha - 486 - 314 * depth * depth) && eval < alpha - 348 - 258 * depth * depth)
{ {
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha); value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha) if (value < alpha)
@ -791,16 +791,16 @@ namespace {
&& depth < 8 && depth < 8
&& eval - futility_margin(depth, improving) - (ss-1)->statScore / 256 >= beta && eval - futility_margin(depth, improving) - (ss-1)->statScore / 256 >= beta
&& eval >= beta && eval >= beta
&& eval < 22266) // larger than VALUE_KNOWN_WIN, but smaller than TB wins. && eval < 26305) // larger than VALUE_KNOWN_WIN, but smaller than TB wins.
return eval; return eval;
// Step 9. Null move search with verification search (~22 Elo) // Step 9. Null move search with verification search (~22 Elo)
if ( !PvNode if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL && (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 15075 && (ss-1)->statScore < 14695
&& eval >= beta && eval >= beta
&& eval >= ss->staticEval && eval >= ss->staticEval
&& ss->staticEval >= beta - 18 * depth - improvement / 19 + 215 + complexity / 30 && ss->staticEval >= beta - 15 * depth - improvement / 15 + 198 + complexity / 28
&& !excludedMove && !excludedMove
&& pos.non_pawn_material(us) && pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@ -808,7 +808,7 @@ namespace {
assert(eval - beta >= 0); assert(eval - beta >= 0);
// Null move dynamic reduction based on depth, eval and complexity of position // Null move dynamic reduction based on depth, eval and complexity of position
Depth R = std::min(int(eval - beta) / 184, 4) + depth / 3 + 4 - (complexity > 799); Depth R = std::min(int(eval - beta) / 147, 5) + depth / 3 + 4 - (complexity > 753);
ss->currentMove = MOVE_NULL; ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@ -844,7 +844,7 @@ namespace {
} }
} }
probCutBeta = beta + 204 - 52 * improving; probCutBeta = beta + 179 - 46 * improving;
// Step 10. ProbCut (~4 Elo) // Step 10. ProbCut (~4 Elo)
// If we have a good enough capture and a reduced search returns a value // If we have a good enough capture and a reduced search returns a value
@ -920,7 +920,7 @@ namespace {
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 (~0 Elo) // Step 12. A small Probcut idea, when we are in check (~0 Elo)
probCutBeta = beta + 401; probCutBeta = beta + 481;
if ( ss->inCheck if ( ss->inCheck
&& !PvNode && !PvNode
&& depth >= 2 && depth >= 2
@ -1014,14 +1014,14 @@ moves_loop: // When in check, search starts here
if ( !pos.empty(to_sq(move)) if ( !pos.empty(to_sq(move))
&& !givesCheck && !givesCheck
&& !PvNode && !PvNode
&& lmrDepth < 7 && lmrDepth < 6
&& !ss->inCheck && !ss->inCheck
&& ss->staticEval + 424 + 138 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] && ss->staticEval + 281 + 179 * 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)))] / 6 < alpha)
continue; continue;
// SEE based pruning (~9 Elo) // SEE based pruning (~9 Elo)
if (!pos.see_ge(move, Value(-214) * depth)) if (!pos.see_ge(move, Value(-203) * depth))
continue; continue;
} }
else else
@ -1040,11 +1040,11 @@ moves_loop: // When in check, search starts here
// Futility pruning: parent node (~9 Elo) // Futility pruning: parent node (~9 Elo)
if ( !ss->inCheck if ( !ss->inCheck
&& lmrDepth < 11 && lmrDepth < 11
&& ss->staticEval + 147 + 125 * lmrDepth + history / 64 <= alpha) && ss->staticEval + 122 + 138 * lmrDepth + history / 60 <= alpha)
continue; continue;
// Prune moves with negative SEE (~3 Elo) // Prune moves with negative SEE (~3 Elo)
if (!pos.see_ge(move, Value(-23 * lmrDepth * lmrDepth - 31 * lmrDepth))) if (!pos.see_ge(move, Value(-25 * lmrDepth * lmrDepth - 20 * lmrDepth)))
continue; continue;
} }
} }
@ -1059,7 +1059,7 @@ 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 >= 6 + 2 * (PvNode && tte->is_pv()) && depth >= 4 + 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 */
@ -1067,7 +1067,7 @@ 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 - 4 * depth; Value singularBeta = ttValue - 3 * depth;
Depth singularDepth = (depth - 1) / 2; Depth singularDepth = (depth - 1) / 2;
ss->excludedMove = move; ss->excludedMove = move;
@ -1080,7 +1080,7 @@ 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 - 52 && value < singularBeta - 26
&& ss->doubleExtensions <= 8) && ss->doubleExtensions <= 8)
extension = 2; extension = 2;
} }
@ -1100,15 +1100,15 @@ moves_loop: // When in check, search starts here
// Check extensions (~1 Elo) // Check extensions (~1 Elo)
else if ( givesCheck else if ( givesCheck
&& depth > 8 && depth > 9
&& abs(ss->staticEval) > 81) && abs(ss->staticEval) > 71)
extension = 1; extension = 1;
// Quiet ttMove extensions (~0 Elo) // Quiet ttMove extensions (~0 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)] >= 7546) && (*contHist[0])[movedPiece][to_sq(move)] >= 5491)
extension = 1; extension = 1;
} }
@ -1170,18 +1170,18 @@ 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)]
- 4123; - 4334;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo) // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 17417; r -= ss->statScore / 15914;
// In general we want to cap the LMR depth search at newDepth. But if reductions // In general we want to cap the LMR depth search at newDepth. But if reductions
// are really negative and movecount is low, we allow this move to be searched // are really negative and movecount is low, we allow this move to be searched
// deeper than the first move (this may lead to hidden double extensions). // deeper than the first move (this may lead to hidden double extensions).
int deeper = r >= -1 ? 0 int deeper = r >= -1 ? 0
: moveCount <= 5 ? 2 : moveCount <= 4 ? 2
: PvNode && depth > 3 ? 1 : PvNode && depth > 4 ? 1
: cutNode && moveCount <= 7 ? 1 : cutNode && moveCount <= 8 ? 1
: 0; : 0;
Depth d = std::clamp(newDepth - r, 1, newDepth + deeper); Depth d = std::clamp(newDepth - r, 1, newDepth + deeper);
@ -1190,7 +1190,7 @@ moves_loop: // When in check, search starts here
// If the son is reduced and fails high it will be re-searched at full depth // If the son is reduced and fails high it will be re-searched at full depth
doFullDepthSearch = value > alpha && d < newDepth; doFullDepthSearch = value > alpha && d < newDepth;
doDeeperSearch = value > (alpha + 76 + 11 * (newDepth - d)); doDeeperSearch = value > (alpha + 78 + 11 * (newDepth - d));
didLMR = true; didLMR = true;
} }
else else
@ -1342,7 +1342,7 @@ moves_loop: // When in check, search starts here
//or fail low was really bad //or fail low was really bad
bool extraBonus = PvNode bool extraBonus = PvNode
|| cutNode || cutNode
|| bestValue < alpha - 71 * depth; || bestValue < alpha - 70 * depth;
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus)); update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus));
} }
@ -1473,7 +1473,7 @@ moves_loop: // When in check, search starts here
if (PvNode && bestValue > alpha) if (PvNode && bestValue > alpha)
alpha = bestValue; alpha = bestValue;
futilityBase = bestValue + 139; futilityBase = bestValue + 118;
} }
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,