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Code Issues Releases Wiki Activity

Further reduce sleep lock contention

Browse source 
Use one sleep lock per thread insted of a single one shared.

Also renamed WaitLock in SleepLock.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-12-12 11:06:36 +01:00
parent dedc6d7588
commit 4ad03c9bad
1 changed files with 19 additions and 15 deletions
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34
src/search.cpp
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@ -94,8 +94,8 @@ namespace {
int ActiveThreads; int ActiveThreads;
volatile bool AllThreadsShouldExit; volatile bool AllThreadsShouldExit;
Thread threads[MAX_THREADS]; Thread threads[MAX_THREADS];
Lock MPLock, WaitLock; Lock MPLock, SleepLock[MAX_THREADS];
WaitCondition WaitCond[MAX_THREADS]; WaitCondition SleepCond[MAX_THREADS];
}; };
@ -2227,7 +2227,7 @@ split_point_start: // At split points actual search starts from here
threads[threadID].state = THREAD_AVAILABLE; threads[threadID].state = THREAD_AVAILABLE;
// Grab the lock to avoid races with wake_sleeping_thread() // Grab the lock to avoid races with wake_sleeping_thread()
lock_grab(&WaitLock); lock_grab(&SleepLock[threadID]);
// If we are master and all slaves have finished do not go to sleep // If we are master and all slaves have finished do not go to sleep
for (i = 0; sp && i < ActiveThreads && !sp->slaves[i]; i++) {} for (i = 0; sp && i < ActiveThreads && !sp->slaves[i]; i++) {}
@ -2235,15 +2235,15 @@ split_point_start: // At split points actual search starts from here
if (allFinished || AllThreadsShouldExit) if (allFinished || AllThreadsShouldExit)
{ {
lock_release(&WaitLock); lock_release(&SleepLock[threadID]);
break; break;
} }
// Do sleep here after retesting sleep conditions // Do sleep here after retesting sleep conditions
if (threadID >= ActiveThreads || threads[threadID].state == THREAD_AVAILABLE) if (threadID >= ActiveThreads || threads[threadID].state == THREAD_AVAILABLE)
cond_wait(&WaitCond[threadID], &WaitLock); cond_wait(&SleepCond[threadID], &SleepLock[threadID]);
lock_release(&WaitLock); lock_release(&SleepLock[threadID]);
} }
// If this thread has been assigned work, launch a search // If this thread has been assigned work, launch a search
@ -2308,10 +2308,12 @@ split_point_start: // At split points actual search starts from here
// Initialize global locks // Initialize global locks
lock_init(&MPLock); lock_init(&MPLock);
lock_init(&WaitLock);
for (i = 0; i < MAX_THREADS; i++) for (i = 0; i < MAX_THREADS; i++)
cond_init(&WaitCond[i]); {
lock_init(&SleepLock[i]);
cond_init(&SleepCond[i]);
}
// Initialize splitPoints[] locks // Initialize splitPoints[] locks
for (i = 0; i < MAX_THREADS; i++) for (i = 0; i < MAX_THREADS; i++)
@ -2372,12 +2374,14 @@ split_point_start: // At split points actual search starts from here
for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
lock_destroy(&(threads[i].splitPoints[j].lock)); lock_destroy(&(threads[i].splitPoints[j].lock));
lock_destroy(&WaitLock);
lock_destroy(&MPLock); lock_destroy(&MPLock);
// Now we can safely destroy the wait conditions // Now we can safely destroy the wait conditions
for (int i = 0; i < MAX_THREADS; i++) for (int i = 0; i < MAX_THREADS; i++)
cond_destroy(&WaitCond[i]); {
lock_destroy(&SleepLock[i]);
cond_destroy(&SleepCond[i]);
}
} }
@ -2565,14 +2569,14 @@ split_point_start: // At split points actual search starts from here
} }
// wake_sleeping_thread() wakes up all sleeping threads when it is time // wake_sleeping_thread() wakes up the thread with the given threadID
// to start a new search from the root. // when it is time to start a new search.
void ThreadsManager::wake_sleeping_thread(int threadID) { void ThreadsManager::wake_sleeping_thread(int threadID) {
lock_grab(&WaitLock); lock_grab(&SleepLock[threadID]);
cond_signal(&WaitCond[threadID]); cond_signal(&SleepCond[threadID]);
lock_release(&WaitLock); lock_release(&SleepLock[threadID]);
} }