/* __ompc_remove_task_from_pool_simple_2level:
* Takes a task from the task pool. First tries to get a task from the current
* thread's task queue. If that doesn't work, then it will look for work in
* the community queue. If that's also empty, then it will attempt to steal a
* task from another task queue (so long as there are no other tasks, not in a
* barrier, that are tied to the current thread).
*
* Note: The restriction on stealing is overly conservative. Even if there are
* tasks tied to the current thread and not in a barrier ([*]), we should be
* able to steal any untied tasks, or tied tasks that descend from all tasks
* in [*]. But this implementation does not separate untied tasks from tied
* tasks, and also does not track descendants in the task pool.
*/
omp_task_t *__ompc_remove_task_from_pool_simple_2level(omp_task_pool_t *pool)
{
omp_task_t *task, *current_task;
omp_team_t *team;
omp_v_thread_t *current_thread;
omp_queue_t *my_queue;
omp_queue_t *victim_queue;
omp_task_queue_level_t *per_thread, *community;
int myid = __omp_myid;
Is_True(pool != NULL, ("__ompc_remove_task_from_pool: task pool is uninitialized"));
current_task = __omp_current_task;
current_thread = __omp_current_v_thread;
per_thread = &pool->level[PER_THREAD];
community = &pool->level[COMMUNITY];
task = __ompc_task_queue_get(&per_thread->task_queue[myid]);
/* if no task in local queue, we will look in another queue so long as there
* are no suspended tasks tied to thread and the current task is either in a
* barrier or its not tied
*/
if (task == NULL && !current_thread->num_suspended_tied_tasks &&
(__ompc_task_state_is_in_barrier(current_task) ||
!__ompc_task_is_tied(current_task))) {
if (__omp_task_chunk_size > 1) {
/* this will steal a chunk of tasks, instead of just 1, from the
* community
* queue */
task = __ompc_task_queue_steal_chunk(community->task_queue,
&per_thread->task_queue[myid],
__omp_task_chunk_size);
} else {
task = __ompc_task_queue_steal(community->task_queue);
}
if (task == NULL) {
int first_victim, victim = 0;
int team_size = pool->team_size;
victim = (rand_r(&__omp_seed) % (team_size - 1));
if (victim >= myid) victim++;
/* cycle through to find a queue with work to steal */
first_victim = victim;
while (1) {
while (__ompc_queue_is_empty(&per_thread->task_queue[victim])) {
victim++;
if (victim == myid)
victim++;
if (victim == team_size)
victim = 0;
if (victim == first_victim)
return NULL;
}
task = __ompc_task_queue_steal(&per_thread->task_queue[victim]);
if ( task != NULL ) return task;
}
}
}
return task;
}
/* __ompc_remove_task_from_pool_default:
*Takes task from the task pool.
*
* Takes a task from the task pool. First tries to get a task from the current
* thread's task queue. If that doesn't work, then it will attempt to steal a
* task from another task queue (so long as there are no other tasks, not in a
* barrier, that are tied to the current thread).
*/
omp_task_t *__ompc_remove_task_from_pool_default(omp_task_pool_t *pool)
{
omp_task_t *task, *current_task;
omp_team_t *team;
omp_v_thread_t *current_thread;
omp_queue_t *my_queue;
omp_queue_t *victim_queue;
omp_task_queue_level_t *per_thread;
int myid = __omp_myid;
Is_True(pool != NULL, ("__ompc_remove_task_from_pool: task pool is uninitialized"));
current_task = __omp_current_task;
current_thread = __omp_current_v_thread;
per_thread = &pool->level[PER_THREAD];
/* We get only from the tail for tied tasks. This is necessary to guarantee
* that tied tasks are only scheduled if they are descendants of every
* suspended tied task not at a barrier */
task = __ompc_queue_get_tail(&per_thread->task_queue[TIED_IDX(myid)]);
/* for untied tasks, we can get from the head or tail, depending on what
* O64_OMP_TASK_QUEUE is set to */
if (task == NULL)
task = __ompc_task_queue_get(&per_thread->task_queue[UNTIED_IDX(myid)]);
/* check if there are any untied tasks available in the other task queues */
if (task == NULL) {
int first_victim, victim = 0;
int team_size = pool->team_size;
if (team_size < 2)
return NULL;
victim = (rand_r(&__omp_seed) % (team_size - 1));
if (victim >= myid) victim++;
/* cycle through to find a queue with work to steal */
first_victim = victim;
while (1) {
while (__ompc_queue_lockless_is_empty(
&per_thread->task_queue[UNTIED_IDX(victim)])) {
victim++;
if (victim == myid)
victim++;
if (victim == team_size)
victim = 0;
if (victim == first_victim)
goto CHECK_TIED_TASK_QUEUES;
}
task = __ompc_task_queue_steal(
&per_thread->task_queue[UNTIED_IDX(victim)]);
if ( task != NULL ) {
/*
if (!__ompc_task_state_is_unscheduled(task)) {
// Is_True(0, ("state of task from queue was not unscheduled"));
printf("\n... (1) skipping over a task with state %s; queue size is %d \n",
__ompc_task_get_state_string(task),
__ompc_queue_num_used_slots(&per_thread->task_queue[UNTIED_IDX(victim)]));
task = NULL;
}
*/
return task;
}
}
}
/* if no task in local queue and no available untied tasks, we will look in
* another queue so long as there are no suspended tasks tied to thread and
* the current task is either in a barrier or its not tied
*/
CHECK_TIED_TASK_QUEUES:
if (task == NULL && !current_thread->num_suspended_tied_tasks &&
(__ompc_task_state_is_in_barrier(current_task) ||
!__ompc_task_is_tied(current_task))) {
int first_victim, victim = 0;
int team_size = pool->team_size;
victim = (rand_r(&__omp_seed) % (team_size - 1));
if (victim >= myid) victim++;
/* cycle through to find a queue with work to steal */
first_victim = victim;
while (1) {
while (__ompc_queue_is_empty(
&per_thread->task_queue[TIED_IDX(victim)])) {
victim++;
if (victim == myid)
victim++;
if (victim == team_size)
victim = 0;
if (victim == first_victim)
return NULL;
}
/* Always steal from the head for tied tasks. Note also that by not
* using the task_queue API, CFIFO implementation will not be used */
task = __ompc_queue_steal_head(
&per_thread->task_queue[TIED_IDX(victim)]);
if ( task != NULL ) {
/*
if (!__ompc_task_state_is_unscheduled(task)) {
// Is_True(0, ("state of task from queue was not unscheduled"));
printf("\n... (2) skipping over a task with state %s; queue size is %d \n",
__ompc_task_get_state_string(task),
__ompc_queue_num_used_slots(&per_thread->task_queue[TIED_IDX(victim)]));
task = NULL;
}
*/
return task;
}
}
}
/*
if ( task != NULL ) {
if (!__ompc_task_state_is_unscheduled(task)) {
// Is_True(0, ("state of task from queue was not unscheduled"));
printf("\n... (3) skipping over a task with state %s; queue size is %d \n",
__ompc_task_get_state_string(task),
__ompc_queue_num_used_slots(&per_thread->task_queue[UNTIED_IDX(myid)]));
task = NULL;
}
}
*/
return task;
}
/* __ompc_remove_task_from_pool_simple:
* Takes a task from the task pool. First tries to get a task from the current
* thread's task queue. If that doesn't work, then it will attempt to steal a
* task from another task queue (so long as there are no other tasks, not in a
* barrier, that are tied to the current thread).
*
* Note: The restriction on stealing is overly conservative. Even if there are
* tasks tied to the current thread and not in a barrier ([*]), we should be
* able to steal any untied tasks, or tied tasks that descend from all tasks
* in [*]. But this implementation does not separate untied tasks from tied
* tasks, and also does not track descendants in the task pool.
*/
omp_task_t *__ompc_remove_task_from_pool_simple(omp_task_pool_t *pool)
{
omp_task_t *task, *current_task;
omp_team_t *team;
omp_v_thread_t *current_thread;
omp_queue_t *my_queue;
omp_queue_t *victim_queue;
omp_task_queue_level_t *per_thread;
int myid = __omp_myid;
int team_size;
Is_True(pool != NULL, ("__ompc_remove_task_from_pool: task pool is uninitialized"));
current_task = __omp_current_task;
current_thread = __omp_current_v_thread;
per_thread = &pool->level[PER_THREAD];
task = __ompc_task_queue_get(&per_thread->task_queue[myid]);
/* if no task in local queue, we will look in another queue so long as there
* are no suspended tasks tied to thread and the current task is either in a
* barrier or its not tied
*/
team_size = pool->team_size;
if (task == NULL && (team_size > 1) &&
!current_thread->num_suspended_tied_tasks &&
(__ompc_task_state_is_in_barrier(current_task) ||
!__ompc_task_is_tied(current_task))) {
int first_victim, victim = 0, go_right;
go_right = (rand_r(&__omp_seed) % (2));
victim = (rand_r(&__omp_seed) % (team_size - 1));
if (victim >= myid) victim++;
first_victim = victim;
if (go_right) {
/* cycle through to find a queue with work to steal */
while (1) {
while (__ompc_queue_is_empty(&per_thread->task_queue[victim])) {
victim++;
if (victim == myid)
victim++;
if (victim == team_size)
victim = 0;
if (victim == first_victim)
return NULL;
}
task = __ompc_task_queue_steal(&per_thread->task_queue[victim]);
if ( task != NULL ) return task;
}
} else {
/* cycle through to find a queue with work to steal */
while (1) {
while (__ompc_queue_is_empty(&per_thread->task_queue[victim])) {
victim--;
if (victim == myid)
victim--;
if (victim == -1)
victim = team_size-1;
if (victim == first_victim)
return NULL;
}
task = __ompc_task_queue_steal(&per_thread->task_queue[victim]);
if ( task != NULL ) return task;
}
}
}
return task;
}
