&& depth >= Threads.minimumSplitDepth
&& ( !thisThread->activeSplitPoint
|| !thisThread->activeSplitPoint->allSlavesSearching
- || ( int(Threads.size()) > MAX_SLAVES_PER_SPLITPOINT
- && thisThread->activeSplitPoint->slavesCount == MAX_SLAVES_PER_SPLITPOINT))
+ || ( 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);
// Pointer 'this_sp' is not null only if we are called from split(), and not
// at the thread creation. This means we are the split point's master.
- SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL;
+ SplitPoint* this_sp = activeSplitPoint;
- assert(!this_sp || (this_sp->masterThread == this && searching));
+ assert(!this_sp || (this_sp->master == this && searching));
while (!exit)
{
Threads.mutex.lock();
assert(activeSplitPoint);
+
SplitPoint* sp = activeSplitPoint;
Threads.mutex.unlock();
// Wake up the master thread so to allow it to return from the idle
// loop in case we are the last slave of the split point.
- if ( this != sp->masterThread
- && sp->slavesMask.none())
+ if (this != sp->master && sp->slavesMask.none())
{
- assert(!sp->masterThread->searching);
- sp->masterThread->notify_one();
+ assert(!sp->master->searching);
+
+ sp->master->notify_one();
}
// After releasing the lock we can't access any SplitPoint related data
// Try to late join to another split point if none of its slaves has
// already finished.
- if (Threads.size() > 2)
+ SplitPoint* bestSp = NULL;
+ int minLevel = INT_MAX;
+
+ for (size_t i = 0; i < Threads.size(); ++i)
{
- SplitPoint *bestSp = NULL;
- int bestThread = 0;
- int bestScore = INT_MAX;
+ const size_t size = Threads[i]->splitPointsSize; // Local copy
+ sp = size ? &Threads[i]->splitPoints[size - 1] : NULL;
- for (size_t i = 0; i < Threads.size(); ++i)
+ 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] : NULL;
+ assert(this != Threads[i]);
+ assert(!(this_sp && this_sp->slavesMask.none()));
+ assert(Threads.size() > 2);
- if ( sp
- && sp->allSlavesSearching
- && sp->slavesCount < MAX_SLAVES_PER_SPLITPOINT
- && available_to(Threads[i]))
+ // 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 = 0;
+ for (SplitPoint* p = Threads[i]->activeSplitPoint; p; p = p->parentSplitPoint)
+ level++;
+
+ if (level < minLevel)
{
- // Compute the recursive split points chain size
- int level = -1;
- for (SplitPoint* spp = Threads[i]->activeSplitPoint; spp; spp = spp->parentSplitPoint)
- level++;
-
- int score = level * 256 * 256 + sp->slavesCount * 256 - sp->depth * 1;
-
- if (score < bestScore)
- {
- bestSp = sp;
- bestThread = i;
- bestScore = score;
- }
+ bestSp = sp;
+ minLevel = level;
}
}
+ }
- if (bestSp)
- {
- sp = bestSp;
-
- // Recheck the conditions under lock protection
- Threads.mutex.lock();
- sp->mutex.lock();
+ if (bestSp)
+ {
+ sp = bestSp;
- if ( sp->allSlavesSearching
- && sp->slavesCount < MAX_SLAVES_PER_SPLITPOINT
- && available_to(Threads[bestThread]))
- {
- sp->slavesMask.set(idx);
- sp->slavesCount++;
- activeSplitPoint = sp;
- searching = true;
- }
+ // Recheck the conditions under lock protection
+ Threads.mutex.lock();
+ sp->mutex.lock();
- sp->mutex.unlock();
- Threads.mutex.unlock();
+ if ( sp->allSlavesSearching
+ && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+ && available_to(sp->master))
+ {
+ sp->slavesMask.set(idx);
+ activeSplitPoint = sp;
+ searching = true;
}
+
+ sp->mutex.unlock();
+ Threads.mutex.unlock();
}
}
- // Grab the lock to avoid races with Thread::notify_one()
+ // Avoid races with notify_one() fired from last slave of the split point
mutex.lock();
// If we are master and all slaves have finished then exit idle_loop
// Loop across all split points and sum accumulated SplitPoint nodes plus
// all the currently active positions nodes.
for (size_t i = 0; i < Threads.size(); ++i)
- for (int j = 0; j < Threads[i]->splitPointsSize; ++j)
+ for (size_t j = 0; j < Threads[i]->splitPointsSize; ++j)
{
SplitPoint& sp = Threads[i]->splitPoints[j];