From 9042846bc7ae69cc3288d85af6bad16208d93a95 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Tue, 4 Aug 2009 16:56:34 -0400 Subject: Btrfs: Allow worker threads to exit when idle The Btrfs worker threads don't currently die off after they have been idle for a while, leading to a lot of threads sitting around doing nothing for each mount. Also, they are unable to start atomically (from end_io hanlders). This commit reworks the worker threads so they can be started from end_io handlers (just setting a flag that asks for a thread to be added at a later date) and so they can exit if they have been idle for a long time. Signed-off-by: Chris Mason --- fs/btrfs/async-thread.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 1b511c109db..a562ad8d83a 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -73,6 +73,15 @@ struct btrfs_workers { /* force completions in the order they were queued */ int ordered; + /* more workers required, but in an interrupt handler */ + int atomic_start_pending; + + /* + * are we allowed to sleep while starting workers or are we required + * to start them at a later time? + */ + int atomic_worker_start; + /* list with all the work threads. The workers on the idle thread * may be actively servicing jobs, but they haven't yet hit the * idle thresh limit above. -- cgit v1.2.3-70-g09d2 From 4e3f9c5042b43301d70781aee4a164a20878066b Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 5 Aug 2009 16:36:45 -0400 Subject: Btrfs: keep irqs on more often in the worker threads The btrfs worker thread spinlock was being used both for the queueing of IO and for the processing of ordered events. The ordered events never happen from end_io handlers, and so they don't need to use the _irq version of spinlocks. This adds a dedicated lock to the ordered lists so they don't have to run with irqs off. Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 23 +++++++++++++---------- fs/btrfs/async-thread.h | 3 +++ 2 files changed, 16 insertions(+), 10 deletions(-) (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index f10c895224a..4b4372df3b6 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -124,14 +124,12 @@ out: static noinline int run_ordered_completions(struct btrfs_workers *workers, struct btrfs_work *work) { - unsigned long flags; - if (!workers->ordered) return 0; set_bit(WORK_DONE_BIT, &work->flags); - spin_lock_irqsave(&workers->lock, flags); + spin_lock(&workers->order_lock); while (1) { if (!list_empty(&workers->prio_order_list)) { @@ -154,17 +152,17 @@ static noinline int run_ordered_completions(struct btrfs_workers *workers, if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags)) break; - spin_unlock_irqrestore(&workers->lock, flags); + spin_unlock(&workers->order_lock); work->ordered_func(work); /* now take the lock again and call the freeing code */ - spin_lock_irqsave(&workers->lock, flags); + spin_lock(&workers->order_lock); list_del(&work->order_list); work->ordered_free(work); } - spin_unlock_irqrestore(&workers->lock, flags); + spin_unlock(&workers->order_lock); return 0; } @@ -345,6 +343,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max) INIT_LIST_HEAD(&workers->order_list); INIT_LIST_HEAD(&workers->prio_order_list); spin_lock_init(&workers->lock); + spin_lock_init(&workers->order_lock); workers->max_workers = max; workers->idle_thresh = 32; workers->name = name; @@ -374,6 +373,7 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers) INIT_LIST_HEAD(&worker->prio_pending); INIT_LIST_HEAD(&worker->worker_list); spin_lock_init(&worker->lock); + atomic_set(&worker->num_pending, 0); atomic_set(&worker->refs, 1); worker->workers = workers; @@ -453,10 +453,8 @@ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers) again: spin_lock_irqsave(&workers->lock, flags); worker = next_worker(workers); - spin_unlock_irqrestore(&workers->lock, flags); if (!worker) { - spin_lock_irqsave(&workers->lock, flags); if (workers->num_workers >= workers->max_workers) { goto fallback; } else if (workers->atomic_worker_start) { @@ -469,6 +467,7 @@ again: goto again; } } + spin_unlock_irqrestore(&workers->lock, flags); return worker; fallback: @@ -552,14 +551,18 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) worker = find_worker(workers); if (workers->ordered) { - spin_lock_irqsave(&workers->lock, flags); + /* + * you're not allowed to do ordered queues from an + * interrupt handler + */ + spin_lock(&workers->order_lock); if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) { list_add_tail(&work->order_list, &workers->prio_order_list); } else { list_add_tail(&work->order_list, &workers->order_list); } - spin_unlock_irqrestore(&workers->lock, flags); + spin_unlock(&workers->order_lock); } else { INIT_LIST_HEAD(&work->order_list); } diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index a562ad8d83a..fc089b95ec1 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -99,6 +99,9 @@ struct btrfs_workers { /* lock for finding the next worker thread to queue on */ spinlock_t lock; + /* lock for the ordered lists */ + spinlock_t order_lock; + /* extra name for this worker, used for current->name */ char *name; }; -- cgit v1.2.3-70-g09d2