bool run ()
{
threadID.store(0);
numFailed.store(0);
size_t numThreads = getNumberOfLogicalThreads();
threadResults.resize(numThreads);
barrier.init(numThreads+1);
/* create threads */
std::vector<thread_t> threads;
for (size_t i=0; i<numThreads; i++)
threads.push_back(createThread((thread_func)thread_alloc,this));
/* run test */
for (size_t i=0; i<1000; i++)
{
for (size_t i=0; i<numThreads; i++) threadResults[i] = 0;
barrier.wait();
barrier.wait();
for (size_t i=0; i<numThreads; i++) numFailed += threadResults[i] != i;
}
/* destroy threads */
for (size_t i=0; i<numThreads; i++)
join(threads[i]);
return numFailed == 0;
}
void TaskSchedulerTBB::ThreadPool::setNumThreads(size_t newNumThreads, bool startThreads)
{
Lock<MutexSys> lock(g_mutex);
if (newNumThreads == 0)
newNumThreads = getNumberOfLogicalThreads();
numThreads = newNumThreads;
if (!startThreads && !running) return;
running = true;
size_t numThreadsActive = numThreadsRunning;
mutex.lock();
numThreadsRunning = newNumThreads;
mutex.unlock();
condition.notify_all();
/* start new threads */
for (size_t t=numThreadsActive; t<numThreads; t++)
{
if (t == 0) continue;
auto pair = std::make_pair(this,t);
threads.push_back(createThread((thread_func)threadPoolFunction,&pair,4*1024*1024,set_affinity ? t : -1));
g_barrier.wait();
}
/* stop some threads if we reduce the number of threads */
for (ssize_t t=numThreadsActive-1; t>=ssize_t(numThreadsRunning); t--) {
if (t == 0) continue;
embree::join(threads.back());
threads.pop_back();
}
}
void threadPoolFunction(std::pair<TaskSchedulerTBB::ThreadPool*,size_t>* pair)
{
TaskSchedulerTBB::ThreadPool* pool = pair->first;
size_t threadIndex = pair->second;
g_barrier.wait();
pool->thread_loop(threadIndex);
}
namespace embree
{
size_t TaskSchedulerTBB::g_numThreads = 0;
__thread TaskSchedulerTBB* TaskSchedulerTBB::g_instance = nullptr;
__thread TaskSchedulerTBB::Thread* TaskSchedulerTBB::thread_local_thread = nullptr;
TaskSchedulerTBB::ThreadPool* TaskSchedulerTBB::threadPool = nullptr;
template<typename Predicate, typename Body>
__forceinline void TaskSchedulerTBB::steal_loop(Thread& thread, const Predicate& pred, const Body& body)
{
while (true)
{
/*! some rounds that yield */
for (size_t i=0; i<32; i++)
{
/*! some spinning rounds */
const size_t threadCount = thread.threadCount();
for (size_t j=0; j<1024; j+=threadCount)
{
if (!pred()) return;
if (thread.scheduler->steal_from_other_threads(thread)) {
i=j=0;
body();
}
}
yield();
}
}
}
/*! run this task */
__dllexport void TaskSchedulerTBB::Task::run (Thread& thread) // FIXME: avoid as many __dllexports as possible
{
/* try to run if not already stolen */
if (try_switch_state(INITIALIZED,DONE))
{
Task* prevTask = thread.task;
thread.task = this;
try {
if (thread.scheduler->cancellingException == nullptr)
closure->execute();
} catch (...) {
if (thread.scheduler->cancellingException == nullptr)
thread.scheduler->cancellingException = std::current_exception();
}
thread.task = prevTask;
add_dependencies(-1);
}
/* steal until all dependencies have completed */
steal_loop(thread,
[&] () { return dependencies>0; },
[&] () { while (thread.tasks.execute_local(thread,this)); });
/* now signal our parent task that we are finished */
if (parent)
parent->add_dependencies(-1);
}
__dllexport bool TaskSchedulerTBB::TaskQueue::execute_local(Thread& thread, Task* parent)
{
/* stop if we run out of local tasks or reach the waiting task */
if (right == 0 || &tasks[right-1] == parent)
return false;
/* execute task */
size_t oldRight = right;
tasks[right-1].run(thread);
if (right != oldRight) {
THROW_RUNTIME_ERROR("you have to wait for spawned subtasks");
}
/* pop task and closure from stack */
right--;
if (tasks[right].stackPtr != -1)
stackPtr = tasks[right].stackPtr;
/* also move left pointer */
if (left >= right) left = right;
return right != 0;
}
bool TaskSchedulerTBB::TaskQueue::steal(Thread& thread)
{
size_t l = left;
if (l < right)
l = atomic_add(&left,1);
else
return false;
if (!tasks[l].try_steal(thread.tasks.tasks[thread.tasks.right]))
return false;
thread.tasks.right++;
return true;
}
/* we steal from the left */
size_t TaskSchedulerTBB::TaskQueue::getTaskSizeAtLeft()
{
if (left >= right) return 0;
return tasks[left].N;
}
static MutexSys g_mutex;
static BarrierSys g_barrier(2);
void threadPoolFunction(std::pair<TaskSchedulerTBB::ThreadPool*,size_t>* pair)
{
TaskSchedulerTBB::ThreadPool* pool = pair->first;
size_t threadIndex = pair->second;
g_barrier.wait();
pool->thread_loop(threadIndex);
}
TaskSchedulerTBB::ThreadPool::ThreadPool(bool set_affinity)
: numThreads(0), numThreadsRunning(0), set_affinity(set_affinity), running(false) {}
__dllexport void TaskSchedulerTBB::ThreadPool::startThreads()
{
if (running) return;
setNumThreads(numThreads,true);
}
void TaskSchedulerTBB::ThreadPool::setNumThreads(size_t newNumThreads, bool startThreads)
{
Lock<MutexSys> lock(g_mutex);
if (newNumThreads == 0)
newNumThreads = getNumberOfLogicalThreads();
numThreads = newNumThreads;
if (!startThreads && !running) return;
running = true;
size_t numThreadsActive = numThreadsRunning;
mutex.lock();
numThreadsRunning = newNumThreads;
mutex.unlock();
condition.notify_all();
/* start new threads */
for (size_t t=numThreadsActive; t<numThreads; t++)
{
if (t == 0) continue;
auto pair = std::make_pair(this,t);
threads.push_back(createThread((thread_func)threadPoolFunction,&pair,4*1024*1024,set_affinity ? t : -1));
g_barrier.wait();
}
/* stop some threads if we reduce the number of threads */
for (ssize_t t=numThreadsActive-1; t>=ssize_t(numThreadsRunning); t--) {
if (t == 0) continue;
embree::join(threads.back());
threads.pop_back();
}
}
TaskSchedulerTBB::ThreadPool::~ThreadPool()
{
/* leave all taskschedulers */
mutex.lock();
numThreadsRunning = 0;
mutex.unlock();
condition.notify_all();
/* wait for threads to terminate */
for (size_t i=0; i<threads.size(); i++)
embree::join(threads[i]);
}
__dllexport void TaskSchedulerTBB::ThreadPool::add(const Ref<TaskSchedulerTBB>& scheduler)
{
mutex.lock();
schedulers.push_back(scheduler);
mutex.unlock();
condition.notify_all();
}
__dllexport void TaskSchedulerTBB::ThreadPool::remove(const Ref<TaskSchedulerTBB>& scheduler)
{
Lock<MutexSys> lock(mutex);
for (std::list<Ref<TaskSchedulerTBB> >::iterator it = schedulers.begin(); it != schedulers.end(); it++) {
if (scheduler == *it) {
schedulers.erase(it);
return;
}
}
}
void TaskSchedulerTBB::ThreadPool::thread_loop(size_t globalThreadIndex)
{
while (globalThreadIndex < numThreadsRunning)
{
Ref<TaskSchedulerTBB> scheduler = NULL;
ssize_t threadIndex = -1;
{
Lock<MutexSys> lock(mutex);
condition.wait(mutex, [&] () { return globalThreadIndex >= numThreadsRunning || !schedulers.empty(); });
if (globalThreadIndex >= numThreadsRunning) break;
scheduler = schedulers.front();
threadIndex = scheduler->allocThreadIndex();
}
scheduler->thread_loop(threadIndex);
}
}
TaskSchedulerTBB::TaskSchedulerTBB()
: threadCounter(0), anyTasksRunning(0), hasRootTask(false)
{
threadLocal.resize(2*getNumberOfLogicalThreads()); // FIXME: this has to be 2x as in the join mode the worker threads also join
for (size_t i=0; i<threadLocal.size(); i++)
threadLocal[i] = nullptr;
}
TaskSchedulerTBB::~TaskSchedulerTBB()
{
assert(threadCounter == 0);
}
#if TASKING_LOCKSTEP
__dllexport size_t TaskSchedulerTBB::threadCount() {
return LockStepTaskScheduler::instance()->getNumThreads();
}
#endif
#if TASKING_TBB
__dllexport size_t TaskSchedulerTBB::threadIndex() {
#if TBB_INTERFACE_VERSION_MAJOR < 8
return 0;
#else
return tbb::task_arena::current_thread_index();
#endif
}
__dllexport size_t TaskSchedulerTBB::threadCount() {
return g_numThreads;
}
#endif
#if TASKING_TBB_INTERNAL
__dllexport size_t TaskSchedulerTBB::threadIndex()
{
Thread* thread = TaskSchedulerTBB::thread();
if (thread) return thread->threadIndex;
else return 0;
}
__dllexport size_t TaskSchedulerTBB::threadCount() {
return threadPool->size();
}
#endif
__dllexport TaskSchedulerTBB* TaskSchedulerTBB::instance()
{
if (g_instance == NULL) {
g_instance = new TaskSchedulerTBB;
g_instance->refInc();
}
return g_instance;
}
void TaskSchedulerTBB::create(size_t numThreads, bool set_affinity)
{
if (!threadPool) threadPool = new TaskSchedulerTBB::ThreadPool(set_affinity);
threadPool->setNumThreads(numThreads,false);
}
void TaskSchedulerTBB::destroy() {
delete threadPool; threadPool = nullptr;
}
__dllexport ssize_t TaskSchedulerTBB::allocThreadIndex()
{
size_t threadIndex = atomic_add(&threadCounter,1);
assert(threadIndex < threadLocal.size());
return threadIndex;
}
void TaskSchedulerTBB::join()
{
mutex.lock();
size_t threadIndex = allocThreadIndex();
condition.wait(mutex, [&] () { return hasRootTask; });
mutex.unlock();
std::exception_ptr except = thread_loop(threadIndex);
if (except != 0) std::rethrow_exception(except);
}
void TaskSchedulerTBB::reset() {
hasRootTask = false;
}
void TaskSchedulerTBB::wait_for_threads(size_t threadCount)
{
while (threadCounter < threadCount-1)
__pause_cpu();
}
__dllexport TaskSchedulerTBB::Thread* TaskSchedulerTBB::thread() {
return thread_local_thread;
}
__dllexport TaskSchedulerTBB::Thread* TaskSchedulerTBB::swapThread(Thread* thread)
{
Thread* old = thread_local_thread;
thread_local_thread = thread;
return old;
}
__dllexport bool TaskSchedulerTBB::wait()
{
Thread* thread = TaskSchedulerTBB::thread();
if (thread == nullptr) return true;
while (thread->tasks.execute_local(*thread,thread->task)) {};
return thread->scheduler->cancellingException == nullptr;
}
std::exception_ptr TaskSchedulerTBB::thread_loop(size_t threadIndex)
{
/* allocate thread structure */
std::unique_ptr<Thread> mthread(new Thread(threadIndex,this)); // too large for stack allocation
Thread& thread = *mthread;
threadLocal[threadIndex] = &thread;
Thread* oldThread = swapThread(&thread);
/* main thread loop */
while (anyTasksRunning)
{
steal_loop(thread,
[&] () { return anyTasksRunning > 0; },
[&] () {
atomic_add(&anyTasksRunning,+1);
while (thread.tasks.execute_local(thread,nullptr));
atomic_add(&anyTasksRunning,-1);
});
}
threadLocal[threadIndex] = nullptr;
swapThread(oldThread);
/* remember exception to throw */
std::exception_ptr except = nullptr;
if (cancellingException != nullptr) except = cancellingException;
/* wait for all threads to terminate */
atomic_add(&threadCounter,-1);
while (threadCounter > 0) yield();
return except;
}
bool TaskSchedulerTBB::steal_from_other_threads(Thread& thread)
{
const size_t threadIndex = thread.threadIndex;
const size_t threadCount = this->threadCounter;
for (size_t i=1; i<threadCount; i++)
{
__pause_cpu(32);
size_t otherThreadIndex = threadIndex+i;
if (otherThreadIndex >= threadCount) otherThreadIndex -= threadCount;
Thread* othread = threadLocal[otherThreadIndex];
if (!othread)
continue;
if (othread->tasks.steal(thread))
return true;
}
return false;
}
__dllexport void TaskSchedulerTBB::startThreads() {
threadPool->startThreads();
}
__dllexport void TaskSchedulerTBB::addScheduler(const Ref<TaskSchedulerTBB>& scheduler) {
threadPool->add(scheduler);
}
__dllexport void TaskSchedulerTBB::removeScheduler(const Ref<TaskSchedulerTBB>& scheduler) {
threadPool->remove(scheduler);
}
}
