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Add support for node limited search

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Handle also the SMP case. This has been quite tricky, not
trivial to enforce the node limit in SMP case becuase
with "helpful master" concept we can have recursive split
points and we cannot lock them all at once so there is the
risk of counting the same nodes more than once.

Anyhow this patch should be race free and counted nodes are
correct.

No functional change.
This commit is contained in:
Marco Costalba
2012-09-30 06:49:56 +02:00
parent e5463eb3ae
commit ed0fb0b05f
3 changed files with 48 additions and 12 deletions
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44
src/search.cpp
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@@ -279,6 +279,8 @@ void Search::think() {
// used to check for remaining available thinking time.
if (Limits.use_time_management())
Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)));
else if (Limits.nodes)
Threads.set_timer(2 * TimerResolution);
else
Threads.set_timer(100);
@@ -566,10 +568,6 @@ namespace {
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
}
// Enforce node limit here. FIXME: This only works with 1 search thread.
if (Limits.nodes && pos.nodes_searched() >= Limits.nodes)
Signals.stop = true;
if (!RootNode)
{
// Step 2. Check for aborted search and immediate draw
@@ -1712,6 +1710,10 @@ void Thread::idle_loop() {
sp->mutex.lock();
assert(sp->activePositions[idx] == NULL);
sp->activePositions[idx] = &pos;
if (sp->nodeType == Root)
search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
else if (sp->nodeType == PV)
@@ -1724,6 +1726,7 @@ void Thread::idle_loop() {
assert(is_searching);
is_searching = false;
sp->activePositions[idx] = NULL;
sp->slavesMask &= ~(1ULL << idx);
sp->nodes += pos.nodes_searched();
@@ -1754,6 +1757,7 @@ void Thread::idle_loop() {
void check_time() {
static Time::point lastInfoTime = Time::now();
int64_t nodes = 0; // Workaround silly 'uninitialized' gcc warning
if (Time::now() - lastInfoTime >= 1000)
{
@@ -1764,6 +1768,35 @@ void check_time() {
if (Limits.ponder)
return;
if (Limits.nodes)
{
Threads.mutex.lock();
nodes = RootPosition.nodes_searched();
// Loop across all split points and sum accumulated SplitPoint nodes plus
// all the currently active slaves positions.
for (size_t i = 0; i < Threads.size(); i++)
for (int j = 0; j < Threads[i].splitPointsCnt; j++)
{
SplitPoint& sp = Threads[i].splitPoints[j];
sp.mutex.lock();
nodes += sp.nodes;
Bitboard sm = sp.slavesMask;
while (sm)
{
Position* pos = sp.activePositions[pop_lsb(&sm)];
nodes += pos ? pos->nodes_searched() : 0;
}
sp.mutex.unlock();
}
Threads.mutex.unlock();
}
Time::point elapsed = Time::now() - SearchTime;
bool stillAtFirstMove = Signals.firstRootMove
&& !Signals.failedLowAtRoot
@@ -1773,6 +1806,7 @@ void check_time() {
|| stillAtFirstMove;
if ( (Limits.use_time_management() && noMoreTime)
|| (Limits.movetime && elapsed >= Limits.movetime))
|| (Limits.movetime && elapsed >= Limits.movetime)
|| (Limits.nodes && nodes >= Limits.nodes))
Signals.stop = true;
}