diff options
author | Brecht Van Lommel <brechtvanlommel@gmail.com> | 2020-04-09 16:51:44 +0300 |
---|---|---|
committer | Jeroen Bakker <j.bakker@atmind.nl> | 2020-04-09 20:18:14 +0300 |
commit | 78f56d5582d71e001cc1326b7182aa39f9bdedec (patch) | |
tree | 4d7a1d97a4691302d912da441d072a6b511d554d /source/blender/blenlib/intern | |
parent | 862ec829422241878b3345661476d8551935aed2 (diff) |
TaskScheduler: Minor Preparations for TBB
Tasks: move priority from task to task pool {rBf7c18df4f599fe39ffc914e645e504fcdbee8636}
Tasks: split task.c into task_pool.cc and task_iterator.c {rB4ada1d267749931ca934a74b14a82479bcaa92e0}
Differential Revision: https://developer.blender.org/D7385
Diffstat (limited to 'source/blender/blenlib/intern')
-rw-r--r-- | source/blender/blenlib/intern/task_iterator.c (renamed from source/blender/blenlib/intern/task.c) | 1045 | ||||
-rw-r--r-- | source/blender/blenlib/intern/task_pool.cc | 1029 |
2 files changed, 1049 insertions, 1025 deletions
diff --git a/source/blender/blenlib/intern/task.c b/source/blender/blenlib/intern/task_iterator.c index 293275c402d..4ac012fa578 100644 --- a/source/blender/blenlib/intern/task.c +++ b/source/blender/blenlib/intern/task_iterator.c @@ -34,994 +34,6 @@ #include "atomic_ops.h" -/* Define this to enable some detailed statistic print. */ -#undef DEBUG_STATS - -/* Types */ - -/* Number of per-thread pre-allocated tasks. - * - * For more details see description of TaskMemPool. - */ -#define MEMPOOL_SIZE 256 - -/* Number of tasks which are pushed directly to local thread queue. - * - * This allows thread to fetch next task without locking the whole queue. - */ -#define LOCAL_QUEUE_SIZE 1 - -/* Number of tasks which are allowed to be scheduled in a delayed manner. - * - * This allows to use less locks per graph node children schedule. More details - * could be found at TaskThreadLocalStorage::do_delayed_push. - */ -#define DELAYED_QUEUE_SIZE 4096 - -#ifndef NDEBUG -# define ASSERT_THREAD_ID(scheduler, thread_id) \ - do { \ - if (!BLI_thread_is_main()) { \ - TaskThread *thread = pthread_getspecific(scheduler->tls_id_key); \ - if (thread == NULL) { \ - BLI_assert(thread_id == 0); \ - } \ - else { \ - BLI_assert(thread_id == thread->id); \ - } \ - } \ - else { \ - BLI_assert(thread_id == 0); \ - } \ - } while (false) -#else -# define ASSERT_THREAD_ID(scheduler, thread_id) -#endif - -typedef struct Task { - struct Task *next, *prev; - - TaskRunFunction run; - void *taskdata; - bool free_taskdata; - TaskFreeFunction freedata; - TaskPool *pool; -} Task; - -/* This is a per-thread storage of pre-allocated tasks. - * - * The idea behind this is simple: reduce amount of malloc() calls when pushing - * new task to the pool. This is done by keeping memory from the tasks which - * were finished already, so instead of freeing that memory we put it to the - * pool for the later re-use. - * - * The tricky part here is to avoid any inter-thread synchronization, hence no - * lock must exist around this pool. The pool will become an owner of the pointer - * from freed task, and only corresponding thread will be able to use this pool - * (no memory stealing and such). - * - * This leads to the following use of the pool: - * - * - task_push() should provide proper thread ID from which the task is being - * pushed from. - * - * - Task allocation function which check corresponding memory pool and if there - * is any memory in there it'll mark memory as re-used, remove it from the pool - * and use that memory for the new task. - * - * At this moment task queue owns the memory. - * - * - When task is done and task_free() is called the memory will be put to the - * pool which corresponds to a thread which handled the task. - */ -typedef struct TaskMemPool { - /* Number of pre-allocated tasks in the pool. */ - int num_tasks; - /* Pre-allocated task memory pointers. */ - Task *tasks[MEMPOOL_SIZE]; -} TaskMemPool; - -#ifdef DEBUG_STATS -typedef struct TaskMemPoolStats { - /* Number of allocations. */ - int num_alloc; - /* Number of avoided allocations (pointer was re-used from the pool). */ - int num_reuse; - /* Number of discarded memory due to pool saturation, */ - int num_discard; -} TaskMemPoolStats; -#endif - -typedef struct TaskThreadLocalStorage { - /* Memory pool for faster task allocation. - * The idea is to re-use memory of finished/discarded tasks by this thread. - */ - TaskMemPool task_mempool; - - /* Local queue keeps thread alive by keeping small amount of tasks ready - * to be picked up without causing global thread locks for synchronization. - */ - int num_local_queue; - Task *local_queue[LOCAL_QUEUE_SIZE]; - - /* Thread can be marked for delayed tasks push. This is helpful when it's - * know that lots of subsequent task pushed will happen from the same thread - * without "interrupting" for task execution. - * - * We try to accumulate as much tasks as possible in a local queue without - * any locks first, and then we push all of them into a scheduler's queue - * from within a single mutex lock. - */ - bool do_delayed_push; - int num_delayed_queue; - Task *delayed_queue[DELAYED_QUEUE_SIZE]; -} TaskThreadLocalStorage; - -struct TaskPool { - TaskScheduler *scheduler; - - volatile size_t num; - ThreadMutex num_mutex; - ThreadCondition num_cond; - - void *userdata; - ThreadMutex user_mutex; - - volatile bool do_cancel; - volatile bool do_work; - - volatile bool is_suspended; - bool start_suspended; - ListBase suspended_queue; - size_t num_suspended; - - /* If set, this pool may never be work_and_wait'ed, which means TaskScheduler - * has to use its special background fallback thread in case we are in - * single-threaded situation. - */ - bool run_in_background; - - /* This is a task scheduler's ID of a thread at which pool was constructed. - * It will be used to access task TLS. - */ - int thread_id; - - /* For the pools which are created from non-main thread which is not a - * scheduler worker thread we can't re-use any of scheduler's threads TLS - * and have to use our own one. - */ - bool use_local_tls; - TaskThreadLocalStorage local_tls; -#ifndef NDEBUG - pthread_t creator_thread_id; -#endif - -#ifdef DEBUG_STATS - TaskMemPoolStats *mempool_stats; -#endif -}; - -struct TaskScheduler { - pthread_t *threads; - struct TaskThread *task_threads; - int num_threads; - bool background_thread_only; - - ListBase queue; - ThreadMutex queue_mutex; - ThreadCondition queue_cond; - - ThreadMutex startup_mutex; - ThreadCondition startup_cond; - volatile int num_thread_started; - - volatile bool do_exit; - - /* NOTE: In pthread's TLS we store the whole TaskThread structure. */ - pthread_key_t tls_id_key; -}; - -typedef struct TaskThread { - TaskScheduler *scheduler; - int id; - TaskThreadLocalStorage tls; -} TaskThread; - -/* Helper */ -BLI_INLINE void task_data_free(Task *task, const int thread_id) -{ - if (task->free_taskdata) { - if (task->freedata) { - task->freedata(task->pool, task->taskdata, thread_id); - } - else { - MEM_freeN(task->taskdata); - } - } -} - -BLI_INLINE void initialize_task_tls(TaskThreadLocalStorage *tls) -{ - memset(tls, 0, sizeof(TaskThreadLocalStorage)); -} - -BLI_INLINE TaskThreadLocalStorage *get_task_tls(TaskPool *pool, const int thread_id) -{ - TaskScheduler *scheduler = pool->scheduler; - BLI_assert(thread_id >= 0); - BLI_assert(thread_id <= scheduler->num_threads); - if (pool->use_local_tls && thread_id == 0) { - BLI_assert(pool->thread_id == 0); - BLI_assert(!BLI_thread_is_main()); - BLI_assert(pthread_equal(pthread_self(), pool->creator_thread_id)); - return &pool->local_tls; - } - if (thread_id == 0) { - BLI_assert(BLI_thread_is_main()); - return &scheduler->task_threads[pool->thread_id].tls; - } - return &scheduler->task_threads[thread_id].tls; -} - -BLI_INLINE void free_task_tls(TaskThreadLocalStorage *tls) -{ - TaskMemPool *task_mempool = &tls->task_mempool; - for (int i = 0; i < task_mempool->num_tasks; i++) { - MEM_freeN(task_mempool->tasks[i]); - } -} - -static Task *task_alloc(TaskPool *pool, const int thread_id) -{ - BLI_assert(thread_id <= pool->scheduler->num_threads); - if (thread_id != -1) { - BLI_assert(thread_id >= 0); - BLI_assert(thread_id <= pool->scheduler->num_threads); - TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); - TaskMemPool *task_mempool = &tls->task_mempool; - /* Try to re-use task memory from a thread local storage. */ - if (task_mempool->num_tasks > 0) { - --task_mempool->num_tasks; - /* Success! We've just avoided task allocation. */ -#ifdef DEBUG_STATS - pool->mempool_stats[thread_id].num_reuse++; -#endif - return task_mempool->tasks[task_mempool->num_tasks]; - } - /* We are doomed to allocate new task data. */ -#ifdef DEBUG_STATS - pool->mempool_stats[thread_id].num_alloc++; -#endif - } - return MEM_mallocN(sizeof(Task), "New task"); -} - -static void task_free(TaskPool *pool, Task *task, const int thread_id) -{ - task_data_free(task, thread_id); - BLI_assert(thread_id >= 0); - BLI_assert(thread_id <= pool->scheduler->num_threads); - if (thread_id == 0) { - BLI_assert(pool->use_local_tls || BLI_thread_is_main()); - } - TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); - TaskMemPool *task_mempool = &tls->task_mempool; - if (task_mempool->num_tasks < MEMPOOL_SIZE - 1) { - /* Successfully allowed the task to be re-used later. */ - task_mempool->tasks[task_mempool->num_tasks] = task; - ++task_mempool->num_tasks; - } - else { - /* Local storage saturated, no other way than just discard - * the memory. - * - * TODO(sergey): We can perhaps store such pointer in a global - * scheduler pool, maybe it'll be faster than discarding and - * allocating again. - */ - MEM_freeN(task); -#ifdef DEBUG_STATS - pool->mempool_stats[thread_id].num_discard++; -#endif - } -} - -/* Task Scheduler */ - -static void task_pool_num_decrease(TaskPool *pool, size_t done) -{ - BLI_mutex_lock(&pool->num_mutex); - - BLI_assert(pool->num >= done); - - pool->num -= done; - - if (pool->num == 0) { - BLI_condition_notify_all(&pool->num_cond); - } - - BLI_mutex_unlock(&pool->num_mutex); -} - -static void task_pool_num_increase(TaskPool *pool, size_t new) -{ - BLI_mutex_lock(&pool->num_mutex); - - pool->num += new; - BLI_condition_notify_all(&pool->num_cond); - - BLI_mutex_unlock(&pool->num_mutex); -} - -static bool task_scheduler_thread_wait_pop(TaskScheduler *scheduler, Task **task) -{ - bool found_task = false; - BLI_mutex_lock(&scheduler->queue_mutex); - - while (!scheduler->queue.first && !scheduler->do_exit) { - BLI_condition_wait(&scheduler->queue_cond, &scheduler->queue_mutex); - } - - do { - Task *current_task; - - /* Assuming we can only have a void queue in 'exit' case here seems logical - * (we should only be here after our worker thread has been woken up from a - * condition_wait(), which only happens after a new task was added to the queue), - * but it is wrong. - * Waiting on condition may wake up the thread even if condition is not signaled - * (spurious wake-ups), and some race condition may also empty the queue **after** - * condition has been signaled, but **before** awoken thread reaches this point... - * See http://stackoverflow.com/questions/8594591 - * - * So we only abort here if do_exit is set. - */ - if (scheduler->do_exit) { - BLI_mutex_unlock(&scheduler->queue_mutex); - return false; - } - - for (current_task = scheduler->queue.first; current_task != NULL; - current_task = current_task->next) { - TaskPool *pool = current_task->pool; - - if (scheduler->background_thread_only && !pool->run_in_background) { - continue; - } - - *task = current_task; - found_task = true; - BLI_remlink(&scheduler->queue, *task); - break; - } - if (!found_task) { - BLI_condition_wait(&scheduler->queue_cond, &scheduler->queue_mutex); - } - } while (!found_task); - - BLI_mutex_unlock(&scheduler->queue_mutex); - - return true; -} - -BLI_INLINE void handle_local_queue(TaskThreadLocalStorage *tls, const int thread_id) -{ - BLI_assert(!tls->do_delayed_push); - while (tls->num_local_queue > 0) { - /* We pop task from queue before handling it so handler of the task can - * push next job to the local queue. - */ - tls->num_local_queue--; - Task *local_task = tls->local_queue[tls->num_local_queue]; - /* TODO(sergey): Double-check work_and_wait() doesn't handle other's - * pool tasks. - */ - TaskPool *local_pool = local_task->pool; - local_task->run(local_pool, local_task->taskdata, thread_id); - task_free(local_pool, local_task, thread_id); - } - BLI_assert(!tls->do_delayed_push); -} - -static void *task_scheduler_thread_run(void *thread_p) -{ - TaskThread *thread = (TaskThread *)thread_p; - TaskThreadLocalStorage *tls = &thread->tls; - TaskScheduler *scheduler = thread->scheduler; - int thread_id = thread->id; - Task *task; - - pthread_setspecific(scheduler->tls_id_key, thread); - - /* signal the main thread when all threads have started */ - BLI_mutex_lock(&scheduler->startup_mutex); - scheduler->num_thread_started++; - if (scheduler->num_thread_started == scheduler->num_threads) { - BLI_condition_notify_one(&scheduler->startup_cond); - } - BLI_mutex_unlock(&scheduler->startup_mutex); - - /* keep popping off tasks */ - while (task_scheduler_thread_wait_pop(scheduler, &task)) { - TaskPool *pool = task->pool; - - /* run task */ - BLI_assert(!tls->do_delayed_push); - task->run(pool, task->taskdata, thread_id); - BLI_assert(!tls->do_delayed_push); - - /* delete task */ - task_free(pool, task, thread_id); - - /* Handle all tasks from local queue. */ - handle_local_queue(tls, thread_id); - - /* notify pool task was done */ - task_pool_num_decrease(pool, 1); - } - - return NULL; -} - -TaskScheduler *BLI_task_scheduler_create(int num_threads) -{ - TaskScheduler *scheduler = MEM_callocN(sizeof(TaskScheduler), "TaskScheduler"); - - /* multiple places can use this task scheduler, sharing the same - * threads, so we keep track of the number of users. */ - scheduler->do_exit = false; - - BLI_listbase_clear(&scheduler->queue); - BLI_mutex_init(&scheduler->queue_mutex); - BLI_condition_init(&scheduler->queue_cond); - - BLI_mutex_init(&scheduler->startup_mutex); - BLI_condition_init(&scheduler->startup_cond); - scheduler->num_thread_started = 0; - - if (num_threads == 0) { - /* automatic number of threads will be main thread + num cores */ - num_threads = BLI_system_thread_count(); - } - - /* main thread will also work, so we count it too */ - num_threads -= 1; - - /* Add background-only thread if needed. */ - if (num_threads == 0) { - scheduler->background_thread_only = true; - num_threads = 1; - } - - scheduler->task_threads = MEM_mallocN(sizeof(TaskThread) * (num_threads + 1), - "TaskScheduler task threads"); - - /* Initialize TLS for main thread. */ - initialize_task_tls(&scheduler->task_threads[0].tls); - - pthread_key_create(&scheduler->tls_id_key, NULL); - - /* launch threads that will be waiting for work */ - if (num_threads > 0) { - int i; - - scheduler->num_threads = num_threads; - scheduler->threads = MEM_callocN(sizeof(pthread_t) * num_threads, "TaskScheduler threads"); - - for (i = 0; i < num_threads; i++) { - TaskThread *thread = &scheduler->task_threads[i + 1]; - thread->scheduler = scheduler; - thread->id = i + 1; - initialize_task_tls(&thread->tls); - - if (pthread_create(&scheduler->threads[i], NULL, task_scheduler_thread_run, thread) != 0) { - fprintf(stderr, "TaskScheduler failed to launch thread %d/%d\n", i, num_threads); - } - } - } - - /* Wait for all worker threads to start before returning to caller to prevent the case where - * threads are still starting and pthread_join is called, which causes a deadlock on pthreads4w. - */ - BLI_mutex_lock(&scheduler->startup_mutex); - /* NOTE: Use loop here to avoid false-positive everything-is-ready caused by spontaneous thread - * wake up. */ - while (scheduler->num_thread_started != num_threads) { - BLI_condition_wait(&scheduler->startup_cond, &scheduler->startup_mutex); - } - BLI_mutex_unlock(&scheduler->startup_mutex); - - return scheduler; -} - -void BLI_task_scheduler_free(TaskScheduler *scheduler) -{ - Task *task; - - /* stop all waiting threads */ - BLI_mutex_lock(&scheduler->queue_mutex); - scheduler->do_exit = true; - BLI_condition_notify_all(&scheduler->queue_cond); - BLI_mutex_unlock(&scheduler->queue_mutex); - - pthread_key_delete(scheduler->tls_id_key); - - /* delete threads */ - if (scheduler->threads) { - int i; - - for (i = 0; i < scheduler->num_threads; i++) { - if (pthread_join(scheduler->threads[i], NULL) != 0) { - fprintf(stderr, "TaskScheduler failed to join thread %d/%d\n", i, scheduler->num_threads); - } - } - - MEM_freeN(scheduler->threads); - } - - /* Delete task thread data */ - if (scheduler->task_threads) { - for (int i = 0; i < scheduler->num_threads + 1; i++) { - TaskThreadLocalStorage *tls = &scheduler->task_threads[i].tls; - free_task_tls(tls); - } - - MEM_freeN(scheduler->task_threads); - } - - /* delete leftover tasks */ - for (task = scheduler->queue.first; task; task = task->next) { - task_data_free(task, 0); - } - BLI_freelistN(&scheduler->queue); - - /* delete mutex/condition */ - BLI_mutex_end(&scheduler->queue_mutex); - BLI_condition_end(&scheduler->queue_cond); - BLI_mutex_end(&scheduler->startup_mutex); - BLI_condition_end(&scheduler->startup_cond); - - MEM_freeN(scheduler); -} - -int BLI_task_scheduler_num_threads(TaskScheduler *scheduler) -{ - return scheduler->num_threads + 1; -} - -static void task_scheduler_push(TaskScheduler *scheduler, Task *task, TaskPriority priority) -{ - task_pool_num_increase(task->pool, 1); - - /* add task to queue */ - BLI_mutex_lock(&scheduler->queue_mutex); - - if (priority == TASK_PRIORITY_HIGH) { - BLI_addhead(&scheduler->queue, task); - } - else { - BLI_addtail(&scheduler->queue, task); - } - - BLI_condition_notify_one(&scheduler->queue_cond); - BLI_mutex_unlock(&scheduler->queue_mutex); -} - -static void task_scheduler_push_all(TaskScheduler *scheduler, - TaskPool *pool, - Task **tasks, - int num_tasks) -{ - if (num_tasks == 0) { - return; - } - - task_pool_num_increase(pool, num_tasks); - - BLI_mutex_lock(&scheduler->queue_mutex); - - for (int i = 0; i < num_tasks; i++) { - BLI_addhead(&scheduler->queue, tasks[i]); - } - - BLI_condition_notify_all(&scheduler->queue_cond); - BLI_mutex_unlock(&scheduler->queue_mutex); -} - -static void task_scheduler_clear(TaskScheduler *scheduler, TaskPool *pool) -{ - Task *task, *nexttask; - size_t done = 0; - - BLI_mutex_lock(&scheduler->queue_mutex); - - /* free all tasks from this pool from the queue */ - for (task = scheduler->queue.first; task; task = nexttask) { - nexttask = task->next; - - if (task->pool == pool) { - task_data_free(task, pool->thread_id); - BLI_freelinkN(&scheduler->queue, task); - - done++; - } - } - - BLI_mutex_unlock(&scheduler->queue_mutex); - - /* notify done */ - task_pool_num_decrease(pool, done); -} - -/* Task Pool */ - -static TaskPool *task_pool_create_ex(TaskScheduler *scheduler, - void *userdata, - const bool is_background, - const bool is_suspended) -{ - TaskPool *pool = MEM_mallocN(sizeof(TaskPool), "TaskPool"); - -#ifndef NDEBUG - /* Assert we do not try to create a background pool from some parent task - - * those only work OK from main thread. */ - if (is_background) { - const pthread_t thread_id = pthread_self(); - int i = scheduler->num_threads; - - while (i--) { - BLI_assert(!pthread_equal(scheduler->threads[i], thread_id)); - } - } -#endif - - pool->scheduler = scheduler; - pool->num = 0; - pool->do_cancel = false; - pool->do_work = false; - pool->is_suspended = is_suspended; - pool->start_suspended = is_suspended; - pool->num_suspended = 0; - pool->suspended_queue.first = pool->suspended_queue.last = NULL; - pool->run_in_background = is_background; - pool->use_local_tls = false; - - BLI_mutex_init(&pool->num_mutex); - BLI_condition_init(&pool->num_cond); - - pool->userdata = userdata; - BLI_mutex_init(&pool->user_mutex); - - if (BLI_thread_is_main()) { - pool->thread_id = 0; - } - else { - TaskThread *thread = pthread_getspecific(scheduler->tls_id_key); - if (thread == NULL) { - /* NOTE: Task pool is created from non-main thread which is not - * managed by the task scheduler. We identify ourselves as thread ID - * 0 but we do not use scheduler's TLS storage and use our own - * instead to avoid any possible threading conflicts. - */ - pool->thread_id = 0; - pool->use_local_tls = true; -#ifndef NDEBUG - pool->creator_thread_id = pthread_self(); -#endif - initialize_task_tls(&pool->local_tls); - } - else { - pool->thread_id = thread->id; - } - } - -#ifdef DEBUG_STATS - pool->mempool_stats = MEM_callocN(sizeof(*pool->mempool_stats) * (scheduler->num_threads + 1), - "per-taskpool mempool stats"); -#endif - - /* Ensure malloc will go fine from threads, - * - * This is needed because we could be in main thread here - * and malloc could be non-thread safe at this point because - * no other jobs are running. - */ - BLI_threaded_malloc_begin(); - - return pool; -} - -/** - * Create a normal task pool. Tasks will be executed as soon as they are added. - */ -TaskPool *BLI_task_pool_create(TaskScheduler *scheduler, void *userdata) -{ - return task_pool_create_ex(scheduler, userdata, false, false); -} - -/** - * Create a background task pool. - * In multi-threaded context, there is no differences with #BLI_task_pool_create(), - * but in single-threaded case it is ensured to have at least one worker thread to run on - * (i.e. you don't have to call #BLI_task_pool_work_and_wait - * on it to be sure it will be processed). - * - * \note Background pools are non-recursive - * (that is, you should not create other background pools in tasks assigned to a background pool, - * they could end never being executed, since the 'fallback' background thread is already - * busy with parent task in single-threaded context). - */ -TaskPool *BLI_task_pool_create_background(TaskScheduler *scheduler, void *userdata) -{ - return task_pool_create_ex(scheduler, userdata, true, false); -} - -/** - * Similar to BLI_task_pool_create() but does not schedule any tasks for execution - * for until BLI_task_pool_work_and_wait() is called. This helps reducing threading - * overhead when pushing huge amount of small initial tasks from the main thread. - */ -TaskPool *BLI_task_pool_create_suspended(TaskScheduler *scheduler, void *userdata) -{ - return task_pool_create_ex(scheduler, userdata, false, true); -} - -void BLI_task_pool_free(TaskPool *pool) -{ - BLI_task_pool_cancel(pool); - - BLI_mutex_end(&pool->num_mutex); - BLI_condition_end(&pool->num_cond); - - BLI_mutex_end(&pool->user_mutex); - -#ifdef DEBUG_STATS - printf("Thread ID Allocated Reused Discarded\n"); - for (int i = 0; i < pool->scheduler->num_threads + 1; i++) { - printf("%02d %05d %05d %05d\n", - i, - pool->mempool_stats[i].num_alloc, - pool->mempool_stats[i].num_reuse, - pool->mempool_stats[i].num_discard); - } - MEM_freeN(pool->mempool_stats); -#endif - - if (pool->use_local_tls) { - free_task_tls(&pool->local_tls); - } - - MEM_freeN(pool); - - BLI_threaded_malloc_end(); -} - -BLI_INLINE bool task_can_use_local_queues(TaskPool *pool, int thread_id) -{ - return (thread_id != -1 && (thread_id != pool->thread_id || pool->do_work)); -} - -static void task_pool_push(TaskPool *pool, - TaskRunFunction run, - void *taskdata, - bool free_taskdata, - TaskFreeFunction freedata, - TaskPriority priority, - int thread_id) -{ - /* Allocate task and fill it's properties. */ - Task *task = task_alloc(pool, thread_id); - task->run = run; - task->taskdata = taskdata; - task->free_taskdata = free_taskdata; - task->freedata = freedata; - task->pool = pool; - /* For suspended pools we put everything yo a global queue first - * and exit as soon as possible. - * - * This tasks will be moved to actual execution when pool is - * activated by work_and_wait(). - */ - if (pool->is_suspended) { - BLI_addhead(&pool->suspended_queue, task); - atomic_fetch_and_add_z(&pool->num_suspended, 1); - return; - } - /* Populate to any local queue first, this is cheapest push ever. */ - if (task_can_use_local_queues(pool, thread_id)) { - ASSERT_THREAD_ID(pool->scheduler, thread_id); - TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); - /* Try to push to a local execution queue. - * These tasks will be picked up next. - */ - if (tls->num_local_queue < LOCAL_QUEUE_SIZE) { - tls->local_queue[tls->num_local_queue] = task; - tls->num_local_queue++; - return; - } - /* If we are in the delayed tasks push mode, we push tasks to a - * temporary local queue first without any locks, and then move them - * to global execution queue with a single lock. - */ - if (tls->do_delayed_push && tls->num_delayed_queue < DELAYED_QUEUE_SIZE) { - tls->delayed_queue[tls->num_delayed_queue] = task; - tls->num_delayed_queue++; - return; - } - } - /* Do push to a global execution pool, slowest possible method, - * causes quite reasonable amount of threading overhead. - */ - task_scheduler_push(pool->scheduler, task, priority); -} - -void BLI_task_pool_push_ex(TaskPool *pool, - TaskRunFunction run, - void *taskdata, - bool free_taskdata, - TaskFreeFunction freedata, - TaskPriority priority) -{ - task_pool_push(pool, run, taskdata, free_taskdata, freedata, priority, -1); -} - -void BLI_task_pool_push( - TaskPool *pool, TaskRunFunction run, void *taskdata, bool free_taskdata, TaskPriority priority) -{ - BLI_task_pool_push_ex(pool, run, taskdata, free_taskdata, NULL, priority); -} - -void BLI_task_pool_push_from_thread(TaskPool *pool, - TaskRunFunction run, - void *taskdata, - bool free_taskdata, - TaskPriority priority, - int thread_id) -{ - task_pool_push(pool, run, taskdata, free_taskdata, NULL, priority, thread_id); -} - -void BLI_task_pool_work_and_wait(TaskPool *pool) -{ - TaskThreadLocalStorage *tls = get_task_tls(pool, pool->thread_id); - TaskScheduler *scheduler = pool->scheduler; - - if (atomic_fetch_and_and_uint8((uint8_t *)&pool->is_suspended, 0)) { - if (pool->num_suspended) { - task_pool_num_increase(pool, pool->num_suspended); - BLI_mutex_lock(&scheduler->queue_mutex); - - BLI_movelisttolist(&scheduler->queue, &pool->suspended_queue); - - BLI_condition_notify_all(&scheduler->queue_cond); - BLI_mutex_unlock(&scheduler->queue_mutex); - - pool->num_suspended = 0; - } - } - - pool->do_work = true; - - ASSERT_THREAD_ID(pool->scheduler, pool->thread_id); - - handle_local_queue(tls, pool->thread_id); - - BLI_mutex_lock(&pool->num_mutex); - - while (pool->num != 0) { - Task *task, *work_task = NULL; - bool found_task = false; - - BLI_mutex_unlock(&pool->num_mutex); - - BLI_mutex_lock(&scheduler->queue_mutex); - - /* find task from this pool. if we get a task from another pool, - * we can get into deadlock */ - - for (task = scheduler->queue.first; task; task = task->next) { - if (task->pool == pool) { - work_task = task; - found_task = true; - BLI_remlink(&scheduler->queue, task); - break; - } - } - - BLI_mutex_unlock(&scheduler->queue_mutex); - - /* if found task, do it, otherwise wait until other tasks are done */ - if (found_task) { - /* run task */ - BLI_assert(!tls->do_delayed_push); - work_task->run(pool, work_task->taskdata, pool->thread_id); - BLI_assert(!tls->do_delayed_push); - - /* delete task */ - task_free(pool, task, pool->thread_id); - - /* Handle all tasks from local queue. */ - handle_local_queue(tls, pool->thread_id); - - /* notify pool task was done */ - task_pool_num_decrease(pool, 1); - } - - BLI_mutex_lock(&pool->num_mutex); - if (pool->num == 0) { - break; - } - - if (!found_task) { - BLI_condition_wait(&pool->num_cond, &pool->num_mutex); - } - } - - BLI_mutex_unlock(&pool->num_mutex); - - BLI_assert(tls->num_local_queue == 0); -} - -void BLI_task_pool_work_wait_and_reset(TaskPool *pool) -{ - BLI_task_pool_work_and_wait(pool); - - pool->do_work = false; - pool->is_suspended = pool->start_suspended; -} - -void BLI_task_pool_cancel(TaskPool *pool) -{ - pool->do_cancel = true; - - task_scheduler_clear(pool->scheduler, pool); - - /* wait until all entries are cleared */ - BLI_mutex_lock(&pool->num_mutex); - while (pool->num) { - BLI_condition_wait(&pool->num_cond, &pool->num_mutex); - } - BLI_mutex_unlock(&pool->num_mutex); - - pool->do_cancel = false; -} - -bool BLI_task_pool_canceled(TaskPool *pool) -{ - return pool->do_cancel; -} - -void *BLI_task_pool_userdata(TaskPool *pool) -{ - return pool->userdata; -} - -ThreadMutex *BLI_task_pool_user_mutex(TaskPool *pool) -{ - return &pool->user_mutex; -} - -void BLI_task_pool_delayed_push_begin(TaskPool *pool, int thread_id) -{ - if (task_can_use_local_queues(pool, thread_id)) { - ASSERT_THREAD_ID(pool->scheduler, thread_id); - TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); - tls->do_delayed_push = true; - } -} - -void BLI_task_pool_delayed_push_end(TaskPool *pool, int thread_id) -{ - if (task_can_use_local_queues(pool, thread_id)) { - ASSERT_THREAD_ID(pool->scheduler, thread_id); - TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); - BLI_assert(tls->do_delayed_push); - task_scheduler_push_all(pool->scheduler, pool, tls->delayed_queue, tls->num_delayed_queue); - tls->do_delayed_push = false; - tls->num_delayed_queue = 0; - } -} - /* Parallel range routines */ /** @@ -1331,8 +343,8 @@ void BLI_task_parallel_range(const int start, return; } - TaskPool *task_pool = range_pool.pool = BLI_task_pool_create_suspended(task_scheduler, - &range_pool); + TaskPool *task_pool = range_pool.pool = BLI_task_pool_create_suspended( + task_scheduler, &range_pool, TASK_PRIORITY_HIGH); range_pool.current_state = &state; @@ -1341,18 +353,15 @@ void BLI_task_parallel_range(const int start, state.tls_data_size = tls_data_size; } + const int thread_id = BLI_task_pool_creator_thread_id(task_pool); for (i = 0; i < num_tasks; i++) { if (use_tls_data) { void *userdata_chunk_local = (char *)flatten_tls_storage + (tls_data_size * (size_t)i); memcpy(userdata_chunk_local, tls_data, tls_data_size); } /* Use this pool's pre-allocated tasks. */ - BLI_task_pool_push_from_thread(task_pool, - parallel_range_func, - POINTER_FROM_INT(i), - false, - TASK_PRIORITY_HIGH, - task_pool->thread_id); + BLI_task_pool_push_from_thread( + task_pool, parallel_range_func, POINTER_FROM_INT(i), false, NULL, thread_id); } BLI_task_pool_work_and_wait(task_pool); @@ -1497,18 +506,14 @@ void BLI_task_parallel_range_pool_work_and_wait(TaskParallelRangePool *range_poo } } - TaskPool *task_pool = range_pool->pool = BLI_task_pool_create_suspended(task_scheduler, - range_pool); + TaskPool *task_pool = range_pool->pool = BLI_task_pool_create_suspended( + task_scheduler, range_pool, TASK_PRIORITY_HIGH); range_pool->current_state = range_pool->parallel_range_states; - + const int thread_id = BLI_task_pool_creator_thread_id(task_pool); for (int i = 0; i < num_tasks; i++) { - BLI_task_pool_push_from_thread(task_pool, - parallel_range_func, - POINTER_FROM_INT(i), - false, - TASK_PRIORITY_HIGH, - task_pool->thread_id); + BLI_task_pool_push_from_thread( + task_pool, parallel_range_func, POINTER_FROM_INT(i), false, NULL, thread_id); } BLI_task_pool_work_and_wait(task_pool); @@ -1527,12 +532,8 @@ void BLI_task_parallel_range_pool_work_and_wait(TaskParallelRangePool *range_poo } if (state->func_finalize != NULL) { - BLI_task_pool_push_from_thread(task_pool, - parallel_range_func_finalize, - state, - false, - TASK_PRIORITY_HIGH, - task_pool->thread_id); + BLI_task_pool_push_from_thread( + task_pool, parallel_range_func_finalize, state, false, NULL, thread_id); } } @@ -1719,24 +720,21 @@ static void task_parallel_iterator_do(const TaskParallelSettings *settings, void *userdata_chunk_array = NULL; const bool use_userdata_chunk = (userdata_chunk_size != 0) && (userdata_chunk != NULL); - TaskPool *task_pool = BLI_task_pool_create_suspended(task_scheduler, state); + TaskPool *task_pool = BLI_task_pool_create_suspended(task_scheduler, state, TASK_PRIORITY_HIGH); if (use_userdata_chunk) { userdata_chunk_array = MALLOCA(userdata_chunk_size * num_tasks); } + const int thread_id = BLI_task_pool_creator_thread_id(task_pool); for (size_t i = 0; i < num_tasks; i++) { if (use_userdata_chunk) { userdata_chunk_local = (char *)userdata_chunk_array + (userdata_chunk_size * i); memcpy(userdata_chunk_local, userdata_chunk, userdata_chunk_size); } /* Use this pool's pre-allocated tasks. */ - BLI_task_pool_push_from_thread(task_pool, - parallel_iterator_func, - userdata_chunk_local, - false, - TASK_PRIORITY_HIGH, - task_pool->thread_id); + BLI_task_pool_push_from_thread( + task_pool, parallel_iterator_func, userdata_chunk_local, false, NULL, thread_id); } BLI_task_pool_work_and_wait(task_pool); @@ -1898,7 +896,7 @@ void BLI_task_parallel_mempool(BLI_mempool *mempool, } task_scheduler = BLI_task_scheduler_get(); - task_pool = BLI_task_pool_create_suspended(task_scheduler, &state); + task_pool = BLI_task_pool_create_suspended(task_scheduler, &state, TASK_PRIORITY_HIGH); num_threads = BLI_task_scheduler_num_threads(task_scheduler); /* The idea here is to prevent creating task for each of the loop iterations @@ -1913,14 +911,11 @@ void BLI_task_parallel_mempool(BLI_mempool *mempool, BLI_mempool_iter *mempool_iterators = BLI_mempool_iter_threadsafe_create(mempool, (size_t)num_tasks); + const int thread_id = BLI_task_pool_creator_thread_id(task_pool); for (i = 0; i < num_tasks; i++) { /* Use this pool's pre-allocated tasks. */ - BLI_task_pool_push_from_thread(task_pool, - parallel_mempool_func, - &mempool_iterators[i], - false, - TASK_PRIORITY_HIGH, - task_pool->thread_id); + BLI_task_pool_push_from_thread( + task_pool, parallel_mempool_func, &mempool_iterators[i], false, NULL, thread_id); } BLI_task_pool_work_and_wait(task_pool); diff --git a/source/blender/blenlib/intern/task_pool.cc b/source/blender/blenlib/intern/task_pool.cc new file mode 100644 index 00000000000..8085d495248 --- /dev/null +++ b/source/blender/blenlib/intern/task_pool.cc @@ -0,0 +1,1029 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +/** \file + * \ingroup bli + * + * A generic task system which can be used for any task based subsystem. + */ + +#include <stdlib.h> + +#include "MEM_guardedalloc.h" + +#include "DNA_listBase.h" + +#include "BLI_listbase.h" +#include "BLI_math.h" +#include "BLI_mempool.h" +#include "BLI_task.h" +#include "BLI_threads.h" + +#include "atomic_ops.h" + +/* Define this to enable some detailed statistic print. */ +#undef DEBUG_STATS + +/* Types */ + +/* Number of per-thread pre-allocated tasks. + * + * For more details see description of TaskMemPool. + */ +#define MEMPOOL_SIZE 256 + +/* Number of tasks which are pushed directly to local thread queue. + * + * This allows thread to fetch next task without locking the whole queue. + */ +#define LOCAL_QUEUE_SIZE 1 + +/* Number of tasks which are allowed to be scheduled in a delayed manner. + * + * This allows to use less locks per graph node children schedule. More details + * could be found at TaskThreadLocalStorage::do_delayed_push. + */ +#define DELAYED_QUEUE_SIZE 4096 + +#ifndef NDEBUG +# define ASSERT_THREAD_ID(scheduler, thread_id) \ + do { \ + if (!BLI_thread_is_main()) { \ + TaskThread *thread = (TaskThread *)pthread_getspecific(scheduler->tls_id_key); \ + if (thread == NULL) { \ + BLI_assert(thread_id == 0); \ + } \ + else { \ + BLI_assert(thread_id == thread->id); \ + } \ + } \ + else { \ + BLI_assert(thread_id == 0); \ + } \ + } while (false) +#else +# define ASSERT_THREAD_ID(scheduler, thread_id) +#endif + +typedef struct Task { + struct Task *next, *prev; + + TaskRunFunction run; + void *taskdata; + bool free_taskdata; + TaskFreeFunction freedata; + TaskPool *pool; +} Task; + +/* This is a per-thread storage of pre-allocated tasks. + * + * The idea behind this is simple: reduce amount of malloc() calls when pushing + * new task to the pool. This is done by keeping memory from the tasks which + * were finished already, so instead of freeing that memory we put it to the + * pool for the later re-use. + * + * The tricky part here is to avoid any inter-thread synchronization, hence no + * lock must exist around this pool. The pool will become an owner of the pointer + * from freed task, and only corresponding thread will be able to use this pool + * (no memory stealing and such). + * + * This leads to the following use of the pool: + * + * - task_push() should provide proper thread ID from which the task is being + * pushed from. + * + * - Task allocation function which check corresponding memory pool and if there + * is any memory in there it'll mark memory as re-used, remove it from the pool + * and use that memory for the new task. + * + * At this moment task queue owns the memory. + * + * - When task is done and task_free() is called the memory will be put to the + * pool which corresponds to a thread which handled the task. + */ +typedef struct TaskMemPool { + /* Number of pre-allocated tasks in the pool. */ + int num_tasks; + /* Pre-allocated task memory pointers. */ + Task *tasks[MEMPOOL_SIZE]; +} TaskMemPool; + +#ifdef DEBUG_STATS +typedef struct TaskMemPoolStats { + /* Number of allocations. */ + int num_alloc; + /* Number of avoided allocations (pointer was re-used from the pool). */ + int num_reuse; + /* Number of discarded memory due to pool saturation, */ + int num_discard; +} TaskMemPoolStats; +#endif + +typedef struct TaskThreadLocalStorage { + /* Memory pool for faster task allocation. + * The idea is to re-use memory of finished/discarded tasks by this thread. + */ + TaskMemPool task_mempool; + + /* Local queue keeps thread alive by keeping small amount of tasks ready + * to be picked up without causing global thread locks for synchronization. + */ + int num_local_queue; + Task *local_queue[LOCAL_QUEUE_SIZE]; + + /* Thread can be marked for delayed tasks push. This is helpful when it's + * know that lots of subsequent task pushed will happen from the same thread + * without "interrupting" for task execution. + * + * We try to accumulate as much tasks as possible in a local queue without + * any locks first, and then we push all of them into a scheduler's queue + * from within a single mutex lock. + */ + bool do_delayed_push; + int num_delayed_queue; + Task *delayed_queue[DELAYED_QUEUE_SIZE]; +} TaskThreadLocalStorage; + +struct TaskPool { + TaskScheduler *scheduler; + + volatile size_t num; + ThreadMutex num_mutex; + ThreadCondition num_cond; + + void *userdata; + ThreadMutex user_mutex; + + volatile bool do_cancel; + volatile bool do_work; + + volatile bool is_suspended; + bool start_suspended; + ListBase suspended_queue; + size_t num_suspended; + + TaskPriority priority; + + /* If set, this pool may never be work_and_wait'ed, which means TaskScheduler + * has to use its special background fallback thread in case we are in + * single-threaded situation. + */ + bool run_in_background; + + /* This is a task scheduler's ID of a thread at which pool was constructed. + * It will be used to access task TLS. + */ + int thread_id; + + /* For the pools which are created from non-main thread which is not a + * scheduler worker thread we can't re-use any of scheduler's threads TLS + * and have to use our own one. + */ + bool use_local_tls; + TaskThreadLocalStorage local_tls; +#ifndef NDEBUG + pthread_t creator_thread_id; +#endif + +#ifdef DEBUG_STATS + TaskMemPoolStats *mempool_stats; +#endif +}; + +struct TaskScheduler { + pthread_t *threads; + struct TaskThread *task_threads; + int num_threads; + bool background_thread_only; + + ListBase queue; + ThreadMutex queue_mutex; + ThreadCondition queue_cond; + + ThreadMutex startup_mutex; + ThreadCondition startup_cond; + volatile int num_thread_started; + + volatile bool do_exit; + + /* NOTE: In pthread's TLS we store the whole TaskThread structure. */ + pthread_key_t tls_id_key; +}; + +typedef struct TaskThread { + TaskScheduler *scheduler; + int id; + TaskThreadLocalStorage tls; +} TaskThread; + +/* Helper */ +BLI_INLINE void task_data_free(Task *task, const int thread_id) +{ + if (task->free_taskdata) { + if (task->freedata) { + task->freedata(task->pool, task->taskdata, thread_id); + } + else { + MEM_freeN(task->taskdata); + } + } +} + +BLI_INLINE void initialize_task_tls(TaskThreadLocalStorage *tls) +{ + memset(tls, 0, sizeof(TaskThreadLocalStorage)); +} + +BLI_INLINE TaskThreadLocalStorage *get_task_tls(TaskPool *pool, const int thread_id) +{ + TaskScheduler *scheduler = pool->scheduler; + BLI_assert(thread_id >= 0); + BLI_assert(thread_id <= scheduler->num_threads); + if (pool->use_local_tls && thread_id == 0) { + BLI_assert(pool->thread_id == 0); + BLI_assert(!BLI_thread_is_main()); + BLI_assert(pthread_equal(pthread_self(), pool->creator_thread_id)); + return &pool->local_tls; + } + if (thread_id == 0) { + BLI_assert(BLI_thread_is_main()); + return &scheduler->task_threads[pool->thread_id].tls; + } + return &scheduler->task_threads[thread_id].tls; +} + +BLI_INLINE void free_task_tls(TaskThreadLocalStorage *tls) +{ + TaskMemPool *task_mempool = &tls->task_mempool; + for (int i = 0; i < task_mempool->num_tasks; i++) { + MEM_freeN(task_mempool->tasks[i]); + } +} + +static Task *task_alloc(TaskPool *pool, const int thread_id) +{ + BLI_assert(thread_id <= pool->scheduler->num_threads); + if (thread_id != -1) { + BLI_assert(thread_id >= 0); + BLI_assert(thread_id <= pool->scheduler->num_threads); + TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); + TaskMemPool *task_mempool = &tls->task_mempool; + /* Try to re-use task memory from a thread local storage. */ + if (task_mempool->num_tasks > 0) { + --task_mempool->num_tasks; + /* Success! We've just avoided task allocation. */ +#ifdef DEBUG_STATS + pool->mempool_stats[thread_id].num_reuse++; +#endif + return task_mempool->tasks[task_mempool->num_tasks]; + } + /* We are doomed to allocate new task data. */ +#ifdef DEBUG_STATS + pool->mempool_stats[thread_id].num_alloc++; +#endif + } + return (Task *)MEM_mallocN(sizeof(Task), "New task"); +} + +static void task_free(TaskPool *pool, Task *task, const int thread_id) +{ + task_data_free(task, thread_id); + BLI_assert(thread_id >= 0); + BLI_assert(thread_id <= pool->scheduler->num_threads); + if (thread_id == 0) { + BLI_assert(pool->use_local_tls || BLI_thread_is_main()); + } + TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); + TaskMemPool *task_mempool = &tls->task_mempool; + if (task_mempool->num_tasks < MEMPOOL_SIZE - 1) { + /* Successfully allowed the task to be re-used later. */ + task_mempool->tasks[task_mempool->num_tasks] = task; + ++task_mempool->num_tasks; + } + else { + /* Local storage saturated, no other way than just discard + * the memory. + * + * TODO(sergey): We can perhaps store such pointer in a global + * scheduler pool, maybe it'll be faster than discarding and + * allocating again. + */ + MEM_freeN(task); +#ifdef DEBUG_STATS + pool->mempool_stats[thread_id].num_discard++; +#endif + } +} + +/* Task Scheduler */ + +static void task_pool_num_decrease(TaskPool *pool, size_t done) +{ + BLI_mutex_lock(&pool->num_mutex); + + BLI_assert(pool->num >= done); + + pool->num -= done; + + if (pool->num == 0) { + BLI_condition_notify_all(&pool->num_cond); + } + + BLI_mutex_unlock(&pool->num_mutex); +} + +static void task_pool_num_increase(TaskPool *pool, size_t new_num) +{ + BLI_mutex_lock(&pool->num_mutex); + + pool->num += new_num; + BLI_condition_notify_all(&pool->num_cond); + + BLI_mutex_unlock(&pool->num_mutex); +} + +static bool task_scheduler_thread_wait_pop(TaskScheduler *scheduler, Task **task) +{ + bool found_task = false; + BLI_mutex_lock(&scheduler->queue_mutex); + + while (!scheduler->queue.first && !scheduler->do_exit) { + BLI_condition_wait(&scheduler->queue_cond, &scheduler->queue_mutex); + } + + do { + Task *current_task; + + /* Assuming we can only have a void queue in 'exit' case here seems logical + * (we should only be here after our worker thread has been woken up from a + * condition_wait(), which only happens after a new task was added to the queue), + * but it is wrong. + * Waiting on condition may wake up the thread even if condition is not signaled + * (spurious wake-ups), and some race condition may also empty the queue **after** + * condition has been signaled, but **before** awoken thread reaches this point... + * See http://stackoverflow.com/questions/8594591 + * + * So we only abort here if do_exit is set. + */ + if (scheduler->do_exit) { + BLI_mutex_unlock(&scheduler->queue_mutex); + return false; + } + + for (current_task = (Task *)scheduler->queue.first; current_task != NULL; + current_task = current_task->next) { + TaskPool *pool = current_task->pool; + + if (scheduler->background_thread_only && !pool->run_in_background) { + continue; + } + + *task = current_task; + found_task = true; + BLI_remlink(&scheduler->queue, *task); + break; + } + if (!found_task) { + BLI_condition_wait(&scheduler->queue_cond, &scheduler->queue_mutex); + } + } while (!found_task); + + BLI_mutex_unlock(&scheduler->queue_mutex); + + return true; +} + +BLI_INLINE void handle_local_queue(TaskThreadLocalStorage *tls, const int thread_id) +{ + BLI_assert(!tls->do_delayed_push); + while (tls->num_local_queue > 0) { + /* We pop task from queue before handling it so handler of the task can + * push next job to the local queue. + */ + tls->num_local_queue--; + Task *local_task = tls->local_queue[tls->num_local_queue]; + /* TODO(sergey): Double-check work_and_wait() doesn't handle other's + * pool tasks. + */ + TaskPool *local_pool = local_task->pool; + local_task->run(local_pool, local_task->taskdata, thread_id); + task_free(local_pool, local_task, thread_id); + } + BLI_assert(!tls->do_delayed_push); +} + +static void *task_scheduler_thread_run(void *thread_p) +{ + TaskThread *thread = (TaskThread *)thread_p; + TaskThreadLocalStorage *tls = &thread->tls; + TaskScheduler *scheduler = thread->scheduler; + int thread_id = thread->id; + Task *task; + + pthread_setspecific(scheduler->tls_id_key, thread); + + /* signal the main thread when all threads have started */ + BLI_mutex_lock(&scheduler->startup_mutex); + scheduler->num_thread_started++; + if (scheduler->num_thread_started == scheduler->num_threads) { + BLI_condition_notify_one(&scheduler->startup_cond); + } + BLI_mutex_unlock(&scheduler->startup_mutex); + + /* keep popping off tasks */ + while (task_scheduler_thread_wait_pop(scheduler, &task)) { + TaskPool *pool = task->pool; + + /* run task */ + BLI_assert(!tls->do_delayed_push); + task->run(pool, task->taskdata, thread_id); + BLI_assert(!tls->do_delayed_push); + + /* delete task */ + task_free(pool, task, thread_id); + + /* Handle all tasks from local queue. */ + handle_local_queue(tls, thread_id); + + /* notify pool task was done */ + task_pool_num_decrease(pool, 1); + } + + return NULL; +} + +TaskScheduler *BLI_task_scheduler_create(int num_threads) +{ + TaskScheduler *scheduler = (TaskScheduler *)MEM_callocN(sizeof(TaskScheduler), "TaskScheduler"); + + /* multiple places can use this task scheduler, sharing the same + * threads, so we keep track of the number of users. */ + scheduler->do_exit = false; + + BLI_listbase_clear(&scheduler->queue); + BLI_mutex_init(&scheduler->queue_mutex); + BLI_condition_init(&scheduler->queue_cond); + + BLI_mutex_init(&scheduler->startup_mutex); + BLI_condition_init(&scheduler->startup_cond); + scheduler->num_thread_started = 0; + + if (num_threads == 0) { + /* automatic number of threads will be main thread + num cores */ + num_threads = BLI_system_thread_count(); + } + + /* main thread will also work, so we count it too */ + num_threads -= 1; + + /* Add background-only thread if needed. */ + if (num_threads == 0) { + scheduler->background_thread_only = true; + num_threads = 1; + } + + scheduler->task_threads = (TaskThread *)MEM_mallocN(sizeof(TaskThread) * (num_threads + 1), + "TaskScheduler task threads"); + + /* Initialize TLS for main thread. */ + initialize_task_tls(&scheduler->task_threads[0].tls); + + pthread_key_create(&scheduler->tls_id_key, NULL); + + /* launch threads that will be waiting for work */ + if (num_threads > 0) { + int i; + + scheduler->num_threads = num_threads; + scheduler->threads = (pthread_t *)MEM_callocN(sizeof(pthread_t) * num_threads, + "TaskScheduler threads"); + + for (i = 0; i < num_threads; i++) { + TaskThread *thread = &scheduler->task_threads[i + 1]; + thread->scheduler = scheduler; + thread->id = i + 1; + initialize_task_tls(&thread->tls); + + if (pthread_create(&scheduler->threads[i], NULL, task_scheduler_thread_run, thread) != 0) { + fprintf(stderr, "TaskScheduler failed to launch thread %d/%d\n", i, num_threads); + } + } + } + + /* Wait for all worker threads to start before returning to caller to prevent the case where + * threads are still starting and pthread_join is called, which causes a deadlock on pthreads4w. + */ + BLI_mutex_lock(&scheduler->startup_mutex); + /* NOTE: Use loop here to avoid false-positive everything-is-ready caused by spontaneous thread + * wake up. */ + while (scheduler->num_thread_started != num_threads) { + BLI_condition_wait(&scheduler->startup_cond, &scheduler->startup_mutex); + } + BLI_mutex_unlock(&scheduler->startup_mutex); + + return scheduler; +} + +void BLI_task_scheduler_free(TaskScheduler *scheduler) +{ + Task *task; + + /* stop all waiting threads */ + BLI_mutex_lock(&scheduler->queue_mutex); + scheduler->do_exit = true; + BLI_condition_notify_all(&scheduler->queue_cond); + BLI_mutex_unlock(&scheduler->queue_mutex); + + pthread_key_delete(scheduler->tls_id_key); + + /* delete threads */ + if (scheduler->threads) { + int i; + + for (i = 0; i < scheduler->num_threads; i++) { + if (pthread_join(scheduler->threads[i], NULL) != 0) { + fprintf(stderr, "TaskScheduler failed to join thread %d/%d\n", i, scheduler->num_threads); + } + } + + MEM_freeN(scheduler->threads); + } + + /* Delete task thread data */ + if (scheduler->task_threads) { + for (int i = 0; i < scheduler->num_threads + 1; i++) { + TaskThreadLocalStorage *tls = &scheduler->task_threads[i].tls; + free_task_tls(tls); + } + + MEM_freeN(scheduler->task_threads); + } + + /* delete leftover tasks */ + for (task = (Task *)scheduler->queue.first; task; task = task->next) { + task_data_free(task, 0); + } + BLI_freelistN(&scheduler->queue); + + /* delete mutex/condition */ + BLI_mutex_end(&scheduler->queue_mutex); + BLI_condition_end(&scheduler->queue_cond); + BLI_mutex_end(&scheduler->startup_mutex); + BLI_condition_end(&scheduler->startup_cond); + + MEM_freeN(scheduler); +} + +int BLI_task_scheduler_num_threads(TaskScheduler *scheduler) +{ + return scheduler->num_threads + 1; +} + +static void task_scheduler_push(TaskScheduler *scheduler, Task *task, TaskPriority priority) +{ + task_pool_num_increase(task->pool, 1); + + /* add task to queue */ + BLI_mutex_lock(&scheduler->queue_mutex); + + if (priority == TASK_PRIORITY_HIGH) { + BLI_addhead(&scheduler->queue, task); + } + else { + BLI_addtail(&scheduler->queue, task); + } + + BLI_condition_notify_one(&scheduler->queue_cond); + BLI_mutex_unlock(&scheduler->queue_mutex); +} + +static void task_scheduler_push_all(TaskScheduler *scheduler, + TaskPool *pool, + Task **tasks, + int num_tasks) +{ + if (num_tasks == 0) { + return; + } + + task_pool_num_increase(pool, num_tasks); + + BLI_mutex_lock(&scheduler->queue_mutex); + + for (int i = 0; i < num_tasks; i++) { + BLI_addhead(&scheduler->queue, tasks[i]); + } + + BLI_condition_notify_all(&scheduler->queue_cond); + BLI_mutex_unlock(&scheduler->queue_mutex); +} + +static void task_scheduler_clear(TaskScheduler *scheduler, TaskPool *pool) +{ + Task *task, *nexttask; + size_t done = 0; + + BLI_mutex_lock(&scheduler->queue_mutex); + + /* free all tasks from this pool from the queue */ + for (task = (Task *)scheduler->queue.first; task; task = nexttask) { + nexttask = task->next; + + if (task->pool == pool) { + task_data_free(task, pool->thread_id); + BLI_freelinkN(&scheduler->queue, task); + + done++; + } + } + + BLI_mutex_unlock(&scheduler->queue_mutex); + + /* notify done */ + task_pool_num_decrease(pool, done); +} + +/* Task Pool */ + +static TaskPool *task_pool_create_ex(TaskScheduler *scheduler, + void *userdata, + const bool is_background, + const bool is_suspended, + TaskPriority priority) +{ + TaskPool *pool = (TaskPool *)MEM_mallocN(sizeof(TaskPool), "TaskPool"); + +#ifndef NDEBUG + /* Assert we do not try to create a background pool from some parent task - + * those only work OK from main thread. */ + if (is_background) { + const pthread_t thread_id = pthread_self(); + int i = scheduler->num_threads; + + while (i--) { + BLI_assert(!pthread_equal(scheduler->threads[i], thread_id)); + } + } +#endif + + pool->scheduler = scheduler; + pool->num = 0; + pool->do_cancel = false; + pool->do_work = false; + pool->is_suspended = is_suspended; + pool->start_suspended = is_suspended; + pool->num_suspended = 0; + pool->suspended_queue.first = pool->suspended_queue.last = NULL; + pool->priority = priority; + pool->run_in_background = is_background; + pool->use_local_tls = false; + + BLI_mutex_init(&pool->num_mutex); + BLI_condition_init(&pool->num_cond); + + pool->userdata = userdata; + BLI_mutex_init(&pool->user_mutex); + + if (BLI_thread_is_main()) { + pool->thread_id = 0; + } + else { + TaskThread *thread = (TaskThread *)pthread_getspecific(scheduler->tls_id_key); + if (thread == NULL) { + /* NOTE: Task pool is created from non-main thread which is not + * managed by the task scheduler. We identify ourselves as thread ID + * 0 but we do not use scheduler's TLS storage and use our own + * instead to avoid any possible threading conflicts. + */ + pool->thread_id = 0; + pool->use_local_tls = true; +#ifndef NDEBUG + pool->creator_thread_id = pthread_self(); +#endif + initialize_task_tls(&pool->local_tls); + } + else { + pool->thread_id = thread->id; + } + } + +#ifdef DEBUG_STATS + pool->mempool_stats = (TaskMemPoolStats *)MEM_callocN( + sizeof(*pool->mempool_stats) * (scheduler->num_threads + 1), "per-taskpool mempool stats"); +#endif + + /* Ensure malloc will go fine from threads, + * + * This is needed because we could be in main thread here + * and malloc could be non-thread safe at this point because + * no other jobs are running. + */ + BLI_threaded_malloc_begin(); + + return pool; +} + +/** + * Create a normal task pool. Tasks will be executed as soon as they are added. + */ +TaskPool *BLI_task_pool_create(TaskScheduler *scheduler, void *userdata, TaskPriority priority) +{ + return task_pool_create_ex(scheduler, userdata, false, false, priority); +} + +/** + * Create a background task pool. + * In multi-threaded context, there is no differences with #BLI_task_pool_create(), + * but in single-threaded case it is ensured to have at least one worker thread to run on + * (i.e. you don't have to call #BLI_task_pool_work_and_wait + * on it to be sure it will be processed). + * + * \note Background pools are non-recursive + * (that is, you should not create other background pools in tasks assigned to a background pool, + * they could end never being executed, since the 'fallback' background thread is already + * busy with parent task in single-threaded context). + */ +TaskPool *BLI_task_pool_create_background(TaskScheduler *scheduler, + void *userdata, + TaskPriority priority) +{ + return task_pool_create_ex(scheduler, userdata, true, false, priority); +} + +/** + * Similar to BLI_task_pool_create() but does not schedule any tasks for execution + * for until BLI_task_pool_work_and_wait() is called. This helps reducing threading + * overhead when pushing huge amount of small initial tasks from the main thread. + */ +TaskPool *BLI_task_pool_create_suspended(TaskScheduler *scheduler, + void *userdata, + TaskPriority priority) +{ + return task_pool_create_ex(scheduler, userdata, false, true, priority); +} + +void BLI_task_pool_free(TaskPool *pool) +{ + BLI_task_pool_cancel(pool); + + BLI_mutex_end(&pool->num_mutex); + BLI_condition_end(&pool->num_cond); + + BLI_mutex_end(&pool->user_mutex); + +#ifdef DEBUG_STATS + printf("Thread ID Allocated Reused Discarded\n"); + for (int i = 0; i < pool->scheduler->num_threads + 1; i++) { + printf("%02d %05d %05d %05d\n", + i, + pool->mempool_stats[i].num_alloc, + pool->mempool_stats[i].num_reuse, + pool->mempool_stats[i].num_discard); + } + MEM_freeN(pool->mempool_stats); +#endif + + if (pool->use_local_tls) { + free_task_tls(&pool->local_tls); + } + + MEM_freeN(pool); + + BLI_threaded_malloc_end(); +} + +BLI_INLINE bool task_can_use_local_queues(TaskPool *pool, int thread_id) +{ + return (thread_id != -1 && (thread_id != pool->thread_id || pool->do_work)); +} + +static void task_pool_push(TaskPool *pool, + TaskRunFunction run, + void *taskdata, + bool free_taskdata, + TaskFreeFunction freedata, + int thread_id) +{ + /* Allocate task and fill it's properties. */ + Task *task = task_alloc(pool, thread_id); + task->run = run; + task->taskdata = taskdata; + task->free_taskdata = free_taskdata; + task->freedata = freedata; + task->pool = pool; + /* For suspended pools we put everything yo a global queue first + * and exit as soon as possible. + * + * This tasks will be moved to actual execution when pool is + * activated by work_and_wait(). + */ + if (pool->is_suspended) { + BLI_addhead(&pool->suspended_queue, task); + atomic_fetch_and_add_z(&pool->num_suspended, 1); + return; + } + /* Populate to any local queue first, this is cheapest push ever. */ + if (task_can_use_local_queues(pool, thread_id)) { + ASSERT_THREAD_ID(pool->scheduler, thread_id); + TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); + /* Try to push to a local execution queue. + * These tasks will be picked up next. + */ + if (tls->num_local_queue < LOCAL_QUEUE_SIZE) { + tls->local_queue[tls->num_local_queue] = task; + tls->num_local_queue++; + return; + } + /* If we are in the delayed tasks push mode, we push tasks to a + * temporary local queue first without any locks, and then move them + * to global execution queue with a single lock. + */ + if (tls->do_delayed_push && tls->num_delayed_queue < DELAYED_QUEUE_SIZE) { + tls->delayed_queue[tls->num_delayed_queue] = task; + tls->num_delayed_queue++; + return; + } + } + /* Do push to a global execution pool, slowest possible method, + * causes quite reasonable amount of threading overhead. + */ + task_scheduler_push(pool->scheduler, task, pool->priority); +} + +void BLI_task_pool_push(TaskPool *pool, + TaskRunFunction run, + void *taskdata, + bool free_taskdata, + TaskFreeFunction freedata) +{ + task_pool_push(pool, run, taskdata, free_taskdata, freedata, -1); +} + +void BLI_task_pool_push_from_thread(TaskPool *pool, + TaskRunFunction run, + void *taskdata, + bool free_taskdata, + TaskFreeFunction freedata, + int thread_id) +{ + task_pool_push(pool, run, taskdata, free_taskdata, freedata, thread_id); +} + +void BLI_task_pool_work_and_wait(TaskPool *pool) +{ + TaskThreadLocalStorage *tls = get_task_tls(pool, pool->thread_id); + TaskScheduler *scheduler = pool->scheduler; + + if (atomic_fetch_and_and_uint8((uint8_t *)&pool->is_suspended, 0)) { + if (pool->num_suspended) { + task_pool_num_increase(pool, pool->num_suspended); + BLI_mutex_lock(&scheduler->queue_mutex); + + BLI_movelisttolist(&scheduler->queue, &pool->suspended_queue); + + BLI_condition_notify_all(&scheduler->queue_cond); + BLI_mutex_unlock(&scheduler->queue_mutex); + + pool->num_suspended = 0; + } + } + + pool->do_work = true; + + ASSERT_THREAD_ID(pool->scheduler, pool->thread_id); + + handle_local_queue(tls, pool->thread_id); + + BLI_mutex_lock(&pool->num_mutex); + + while (pool->num != 0) { + Task *task, *work_task = NULL; + bool found_task = false; + + BLI_mutex_unlock(&pool->num_mutex); + + BLI_mutex_lock(&scheduler->queue_mutex); + + /* find task from this pool. if we get a task from another pool, + * we can get into deadlock */ + + for (task = (Task *)scheduler->queue.first; task; task = task->next) { + if (task->pool == pool) { + work_task = task; + found_task = true; + BLI_remlink(&scheduler->queue, task); + break; + } + } + + BLI_mutex_unlock(&scheduler->queue_mutex); + + /* if found task, do it, otherwise wait until other tasks are done */ + if (found_task) { + /* run task */ + BLI_assert(!tls->do_delayed_push); + work_task->run(pool, work_task->taskdata, pool->thread_id); + BLI_assert(!tls->do_delayed_push); + + /* delete task */ + task_free(pool, task, pool->thread_id); + + /* Handle all tasks from local queue. */ + handle_local_queue(tls, pool->thread_id); + + /* notify pool task was done */ + task_pool_num_decrease(pool, 1); + } + + BLI_mutex_lock(&pool->num_mutex); + if (pool->num == 0) { + break; + } + + if (!found_task) { + BLI_condition_wait(&pool->num_cond, &pool->num_mutex); + } + } + + BLI_mutex_unlock(&pool->num_mutex); + + BLI_assert(tls->num_local_queue == 0); +} + +void BLI_task_pool_work_wait_and_reset(TaskPool *pool) +{ + BLI_task_pool_work_and_wait(pool); + + pool->do_work = false; + pool->is_suspended = pool->start_suspended; +} + +void BLI_task_pool_cancel(TaskPool *pool) +{ + pool->do_cancel = true; + + task_scheduler_clear(pool->scheduler, pool); + + /* wait until all entries are cleared */ + BLI_mutex_lock(&pool->num_mutex); + while (pool->num) { + BLI_condition_wait(&pool->num_cond, &pool->num_mutex); + } + BLI_mutex_unlock(&pool->num_mutex); + + pool->do_cancel = false; +} + +bool BLI_task_pool_canceled(TaskPool *pool) +{ + return pool->do_cancel; +} + +void *BLI_task_pool_userdata(TaskPool *pool) +{ + return pool->userdata; +} + +ThreadMutex *BLI_task_pool_user_mutex(TaskPool *pool) +{ + return &pool->user_mutex; +} + +int BLI_task_pool_creator_thread_id(TaskPool *pool) +{ + return pool->thread_id; +} + +void BLI_task_pool_delayed_push_begin(TaskPool *pool, int thread_id) +{ + if (task_can_use_local_queues(pool, thread_id)) { + ASSERT_THREAD_ID(pool->scheduler, thread_id); + TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); + tls->do_delayed_push = true; + } +} + +void BLI_task_pool_delayed_push_end(TaskPool *pool, int thread_id) +{ + if (task_can_use_local_queues(pool, thread_id)) { + ASSERT_THREAD_ID(pool->scheduler, thread_id); + TaskThreadLocalStorage *tls = get_task_tls(pool, thread_id); + BLI_assert(tls->do_delayed_push); + task_scheduler_push_all(pool->scheduler, pool, tls->delayed_queue, tls->num_delayed_queue); + tls->do_delayed_push = false; + tls->num_delayed_queue = 0; + } +} |