// attacked and undefended squares around our king and the quality of
// the pawn shelter (current 'score' value).
attackUnits = std::min(74, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
- + 8 * ei.kingAdjacentZoneAttacksCount[Them]
+ + 8 * ei.kingAdjacentZoneAttacksCount[Them]
+ 25 * popcount<Max15>(undefended)
- + 11 * (ei.pinnedPieces[Us] != 0)
- - mg_value(score) * 31 / 256
+ + 11 * (ei.pinnedPieces[Us] != 0)
+ - mg_value(score) / 8
- !pos.count<QUEEN>(Them) * 60;
// Analyse the enemy's safe queen contact checks. Firstly, find the
&& Threads.size() >= 2
&& depth >= Threads.minimumSplitDepth
&& ( !thisThread->activeSplitPoint
- || !thisThread->activeSplitPoint->allSlavesSearching)
+ || !thisThread->activeSplitPoint->allSlavesSearching
+ || ( Threads.size() > MAX_SLAVES_PER_SPLITPOINT
+ && thisThread->activeSplitPoint->slavesMask.count() == MAX_SLAVES_PER_SPLITPOINT))
&& thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD)
{
assert(bestValue > -VALUE_INFINITE && bestValue < beta);
// Try to late join to another split point if none of its slaves has
// already finished.
- if (Threads.size() > 2)
- for (size_t i = 0; i < Threads.size(); ++i)
+ SplitPoint* bestSp = NULL;
+ Thread* bestThread = NULL;
+ int bestScore = INT_MAX;
+
+ for (size_t i = 0; i < Threads.size(); ++i)
+ {
+ const size_t size = Threads[i]->splitPointsSize; // Local copy
+ sp = size ? &Threads[i]->splitPoints[size - 1] : nullptr;
+
+ if ( sp
+ && sp->allSlavesSearching
+ && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+ && available_to(Threads[i]))
{
- const int size = Threads[i]->splitPointsSize; // Local copy
- sp = size ? &Threads[i]->splitPoints[size - 1] : nullptr;
+ assert(this != Threads[i]);
+ assert(!(this_sp && this_sp->slavesMask.none()));
+ assert(Threads.size() > 2);
+
+ // Prefer to join to SP with few parents to reduce the probability
+ // that a cut-off occurs above us, and hence we waste our work.
+ int level = -1;
+ for (SplitPoint* spp = Threads[i]->activeSplitPoint; spp; spp = spp->parentSplitPoint)
+ level++;
- if ( sp
- && sp->allSlavesSearching
- && available_to(Threads[i]))
+ int score = level * 256 * 256 + (int)sp->slavesMask.count() * 256 - sp->depth * 1;
+
+ if (score < bestScore)
{
- // Recheck the conditions under lock protection
- Threads.mutex.lock();
- sp->mutex.lock();
-
- if ( sp->allSlavesSearching
- && available_to(Threads[i]))
- {
- sp->slavesMask.set(idx);
- activeSplitPoint = sp;
- searching = true;
- }
-
- sp->mutex.unlock();
- Threads.mutex.unlock();
-
- break; // Just a single attempt
+ bestSp = sp;
+ bestThread = Threads[i];
+ bestScore = score;
}
}
+ }
+
+ if (bestSp)
+ {
+ sp = bestSp;
+
+ // Recheck the conditions under lock protection
+ Threads.mutex.lock();
+ sp->mutex.lock();
+
+ if ( sp->allSlavesSearching
+ && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+ && available_to(bestThread))
+ {
+ sp->slavesMask.set(idx);
+ activeSplitPoint = sp;
+ searching = true;
+ }
+
+ sp->mutex.unlock();
+ Threads.mutex.unlock();
+ }
}
// Grab the lock to avoid races with Thread::notify_one()
// Loop across all split points and sum accumulated SplitPoint nodes plus
// all the currently active positions nodes.
for (Thread* th : Threads)
- for (int i = 0; i < th->splitPointsSize; ++i)
+ for (size_t i = 0; i < th->splitPointsSize; ++i)
{
SplitPoint& sp = th->splitPoints[i];
Thread::Thread() /* : splitPoints() */ { // Initialization of non POD broken in MSVC
searching = false;
- maxPly = splitPointsSize = 0;
+ maxPly = 0;
+ splitPointsSize = 0;
activeSplitPoint = nullptr;
activePosition = nullptr;
idx = Threads.size(); // Starts from 0
// Make a local copy to be sure it doesn't become zero under our feet while
// testing next condition and so leading to an out of bounds access.
- const int size = splitPointsSize;
+ const size_t size = splitPointsSize;
// No split points means that the thread is available as a slave for any
// other thread otherwise apply the "helpful master" concept if possible.
Thread* slave;
- while ((slave = Threads.available_slave(this)) != nullptr)
+ while ( sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+ && (slave = Threads.available_slave(this)) != nullptr)
{
sp.slavesMask.set(slave->idx);
slave->activeSplitPoint = &sp;
struct Thread;
-const int MAX_THREADS = 128;
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
/// SplitPoint struct stores information shared by the threads searching in
/// parallel below the same split point. It is populated at splitting time.
size_t idx;
int maxPly;
SplitPoint* volatile activeSplitPoint;
- volatile int splitPointsSize;
+ volatile size_t splitPointsSize;
volatile bool searching;
};