diff options
| author | Ned Bass <[email protected]> | 2012-01-19 10:33:19 -0800 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2012-01-19 14:42:49 -0800 |
| commit | 3c6ed5410beb7a4f9e0c042229eb63c4c11a5fc9 (patch) | |
| tree | 771bf4bc28c99a21adf88de2aaa9c31c802b83ff | |
| parent | 0bb43ca2823ab55a74565f6e17e2c36749cff3b9 (diff) | |
Taskq locking optimizations
Testing has shown that tq->tq_lock can be highly contended when a
large number of small work items are dispatched. The lock hold time
is reduced by the following changes:
1) Use exclusive threads in the work_waitq
When a single work item is dispatched we only need to wake a single
thread to service it. The current implementation uses non-exclusive
threads so all threads are woken when the dispatcher calls wake_up().
If a large number of threads are in the queue this overhead can become
non-negligible.
2) Conditionally add/remove threads from work waitq
Taskq threads need only add themselves to the work wait queue if
there are no pending work items.
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #32
| -rw-r--r-- | module/spl/spl-taskq.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c index ece99aad6..0b3b3a131 100644 --- a/module/spl/spl-taskq.c +++ b/module/spl/spl-taskq.c @@ -454,17 +454,17 @@ taskq_thread(void *args) while (!kthread_should_stop()) { - add_wait_queue(&tq->tq_work_waitq, &wait); if (list_empty(&tq->tq_pend_list) && list_empty(&tq->tq_prio_list)) { + add_wait_queue_exclusive(&tq->tq_work_waitq, &wait); spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags); schedule(); spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags); + remove_wait_queue(&tq->tq_work_waitq, &wait); } else { __set_current_state(TASK_RUNNING); } - remove_wait_queue(&tq->tq_work_waitq, &wait); if (!list_empty(&tq->tq_prio_list)) pend_list = &tq->tq_prio_list; |