From 7bb5d92de8c4d795e9b393aa5ea9c9ad3e43b199 Mon Sep 17 00:00:00 2001 From: Tim Chase Date: Mon, 8 Feb 2016 13:20:05 -0600 Subject: [PATCH] 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 Signed-off-by: Brian Behlendorf Closes #530 --- module/spl/spl-taskq.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c index 56034c8994..bfcf651af6 100644 --- a/module/spl/spl-taskq.c +++ b/module/spl/spl-taskq.c @@ -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);