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Allow spawning a new thread for TQ_NOQUEUE dispatch with dynamic taskq 

When a TQ_NOQUEUE dispatch is done on a dynamic taskq, allow another
thread to be spawned.  This will cause TQ_NOQUEUE to behave similarly
as it does with non-dynamic taskqs.

Add support for TQ_NOQUEUE to taskq_dispatch_ent().

Signed-off-by: Tim Chase <tim@onlight.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #530
This commit is contained in:
Tim Chase 2016-02-08 13:20:05 -06:00 committed by Brian Behlendorf
parent a6ae97caed
commit 7bb5d92de8
1 changed files with 18 additions and 4 deletions
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22
module/spl/spl-taskq.c
View File

@ -562,16 +562,22 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
/* Do not queue the task unless there is idle thread for it */
ASSERT(tq->tq_nactive <= tq->tq_nthreads);
if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads))
goto out;
if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
/* Dynamic taskq may be able to spawn another thread */
if (!(tq->tq_flags & TASKQ_DYNAMIC) || taskq_thread_spawn(tq) == 0)
goto out;
}
if ((t = task_alloc(tq, flags, &irqflags)) == NULL)
goto out;
spin_lock(&t->tqent_lock);
/* Queue to the front of the list to enforce TQ_NOQUEUE semantics */
if (flags & TQ_NOQUEUE)
list_add(&t->tqent_list, &tq->tq_prio_list);
/* Queue to the priority list instead of the pending list */
if (flags & TQ_FRONT)
else if (flags & TQ_FRONT)
list_add_tail(&t->tqent_list, &tq->tq_prio_list);
else
list_add_tail(&t->tqent_list, &tq->tq_pend_list);
@ -593,7 +599,7 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
wake_up(&tq->tq_work_waitq);
out:
/* Spawn additional taskq threads if required. */
if (tq->tq_nactive == tq->tq_nthreads)
if (!(flags & TQ_NOQUEUE) && tq->tq_nactive == tq->tq_nthreads)
(void) taskq_thread_spawn(tq);
spin_unlock_irqrestore(&tq->tq_lock, irqflags);
@ -665,6 +671,13 @@ taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
goto out;
}
if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
/* Dynamic taskq may be able to spawn another thread */
if (!(tq->tq_flags & TASKQ_DYNAMIC) || taskq_thread_spawn(tq) == 0)
goto out2;
flags |= TQ_FRONT;
}
spin_lock(&t->tqent_lock);
/*
@ -693,6 +706,7 @@ out:
/* Spawn additional taskq threads if required. */
if (tq->tq_nactive == tq->tq_nthreads)
(void) taskq_thread_spawn(tq);
out2:
spin_unlock_irqrestore(&tq->tq_lock, irqflags);
}
EXPORT_SYMBOL(taskq_dispatch_ent);