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Code Issues Releases Wiki Activity

Use proper memory ordering for tasks_running/tasks_ready

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This commit is contained in:
Witold Kręcicki
2018-10-25 06:27:24 +00:00
parent 8fb5bc783f
commit 025c74adee
1 changed files with 14 additions and 7 deletions
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21
lib/isc/task.c
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@@ -915,7 +915,8 @@ push_readyq(isc__taskmgr_t *manager, isc__task_t *task, int c) {
if ((task->flags & TASK_F_PRIVILEGED) != 0)
ENQUEUE(manager->queues[c].ready_priority_tasks, task,
ready_priority_link);
atomic_fetch_add_explicit(&manager->tasks_ready, 1, memory_order_relaxed);
atomic_fetch_add_explicit(&manager->tasks_ready, 1,
memory_order_acquire);
}
static void
@@ -1051,13 +1052,15 @@ dispatch(isc__taskmgr_t *manager, unsigned int threadid) {
INSIST(VALID_TASK(task));
/*
* Note we only unlock the manager lock if we actually
* have a task to do. We must reacquire the manager
* Note we only unlock the queue lock if we actually
* have a task to do. We must reacquire the queue
* lock before exiting the 'if (task != NULL)' block.
*/
UNLOCK(&manager->queues[threadid].lock);
atomic_fetch_add_explicit(&manager->tasks_ready, -1, memory_order_relaxed);
atomic_fetch_add_explicit(&manager->tasks_running, 1, memory_order_relaxed);
RUNTIME_CHECK(atomic_fetch_sub_explicit(&manager->tasks_ready,
1, memory_order_release) > 0);
atomic_fetch_add_explicit(&manager->tasks_running, 1,
memory_order_acquire);
LOCK(&task->lock);
INSIST(task->state == task_state_ready);
@@ -1171,7 +1174,8 @@ dispatch(isc__taskmgr_t *manager, unsigned int threadid) {
if (finished)
task_finished(task);
atomic_fetch_add_explicit(&manager->tasks_running, -1, memory_order_relaxed);
RUNTIME_CHECK(atomic_fetch_sub_explicit(&manager->tasks_running,
1, memory_order_release) > 0);
LOCK(&manager->queues[threadid].lock);
if (requeue) {
/*
@@ -1203,7 +1207,10 @@ dispatch(isc__taskmgr_t *manager, unsigned int threadid) {
* we're stuck. Automatically drop privileges at that
* point and continue with the regular ready queue.
*/
if (atomic_load(&manager->tasks_running) == 0 && manager->mode != isc_taskmgrmode_normal) {
if (atomic_load_explicit(&manager->tasks_running,
memory_order_acquire) == 0 &&
manager->mode != isc_taskmgrmode_normal)
{
bool empty = true;
for (unsigned i=0; i<manager->workers && empty; i++) {
if (i != threadid) {