diff options
Diffstat (limited to 'fs/btrfs/async-thread.c')
| -rw-r--r-- | fs/btrfs/async-thread.c | 107 |
1 files changed, 99 insertions, 8 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 193c84964db9..977bce2ec887 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -30,6 +30,9 @@ #define WORK_ORDER_DONE_BIT 2 #define WORK_HIGH_PRIO_BIT 3 +#define NO_THRESHOLD (-1) +#define DFT_THRESHOLD (32) + /* * container for the kthread task pointer and the list of pending work * One of these is allocated per thread. @@ -737,6 +740,14 @@ struct __btrfs_workqueue_struct { /* Spinlock for ordered_list */ spinlock_t list_lock; + + /* Thresholding related variants */ + atomic_t pending; + int max_active; + int current_max; + int thresh; + unsigned int count; + spinlock_t thres_lock; }; struct btrfs_workqueue_struct { @@ -745,19 +756,34 @@ struct btrfs_workqueue_struct { }; static inline struct __btrfs_workqueue_struct -*__btrfs_alloc_workqueue(char *name, int flags, int max_active) +*__btrfs_alloc_workqueue(char *name, int flags, int max_active, int thresh) { struct __btrfs_workqueue_struct *ret = kzalloc(sizeof(*ret), GFP_NOFS); if (unlikely(!ret)) return NULL; + ret->max_active = max_active; + atomic_set(&ret->pending, 0); + if (thresh == 0) + thresh = DFT_THRESHOLD; + /* For low threshold, disabling threshold is a better choice */ + if (thresh < DFT_THRESHOLD) { + ret->current_max = max_active; + ret->thresh = NO_THRESHOLD; + } else { + ret->current_max = 1; + ret->thresh = thresh; + } + if (flags & WQ_HIGHPRI) ret->normal_wq = alloc_workqueue("%s-%s-high", flags, - max_active, "btrfs", name); + ret->max_active, + "btrfs", name); else ret->normal_wq = alloc_workqueue("%s-%s", flags, - max_active, "btrfs", name); + ret->max_active, "btrfs", + name); if (unlikely(!ret->normal_wq)) { kfree(ret); return NULL; @@ -765,6 +791,7 @@ static inline struct __btrfs_workqueue_struct INIT_LIST_HEAD(&ret->ordered_list); spin_lock_init(&ret->list_lock); + spin_lock_init(&ret->thres_lock); return ret; } @@ -773,7 +800,8 @@ __btrfs_destroy_workqueue(struct __btrfs_workqueue_struct *wq); struct btrfs_workqueue_struct *btrfs_alloc_workqueue(char *name, int flags, - int max_active) + int max_active, + int thresh) { struct btrfs_workqueue_struct *ret = kzalloc(sizeof(*ret), GFP_NOFS); @@ -781,14 +809,15 @@ struct btrfs_workqueue_struct *btrfs_alloc_workqueue(char *name, return NULL; ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI, - max_active); + max_active, thresh); if (unlikely(!ret->normal)) { kfree(ret); return NULL; } if (flags & WQ_HIGHPRI) { - ret->high = __btrfs_alloc_workqueue(name, flags, max_active); + ret->high = __btrfs_alloc_workqueue(name, flags, max_active, + thresh); if (unlikely(!ret->high)) { __btrfs_destroy_workqueue(ret->normal); kfree(ret); @@ -798,6 +827,66 @@ struct btrfs_workqueue_struct *btrfs_alloc_workqueue(char *name, return ret; } +/* + * Hook for threshold which will be called in btrfs_queue_work. + * This hook WILL be called in IRQ handler context, + * so workqueue_set_max_active MUST NOT be called in this hook + */ +static inline void thresh_queue_hook(struct __btrfs_workqueue_struct *wq) +{ + if (wq->thresh == NO_THRESHOLD) + return; + atomic_inc(&wq->pending); +} + +/* + * Hook for threshold which will be called before executing the work, + * This hook is called in kthread content. + * So workqueue_set_max_active is called here. + */ +static inline void thresh_exec_hook(struct __btrfs_workqueue_struct *wq) +{ + int new_max_active; + long pending; + int need_change = 0; + + if (wq->thresh == NO_THRESHOLD) + return; + + atomic_dec(&wq->pending); + spin_lock(&wq->thres_lock); + /* + * Use wq->count to limit the calling frequency of + * workqueue_set_max_active. + */ + wq->count++; + wq->count %= (wq->thresh / 4); + if (!wq->count) + goto out; + new_max_active = wq->current_max; + + /* + * pending may be changed later, but it's OK since we really + * don't need it so accurate to calculate new_max_active. + */ + pending = atomic_read(&wq->pending); + if (pending > wq->thresh) + new_max_active++; + if (pending < wq->thresh / 2) + new_max_active--; + new_max_active = clamp_val(new_max_active, 1, wq->max_active); + if (new_max_active != wq->current_max) { + need_change = 1; + wq->current_max = new_max_active; + } +out: + spin_unlock(&wq->thres_lock); + + if (need_change) { + workqueue_set_max_active(wq->normal_wq, wq->current_max); + } +} + static void run_ordered_work(struct __btrfs_workqueue_struct *wq) { struct list_head *list = &wq->ordered_list; @@ -858,6 +947,7 @@ static void normal_work_helper(struct work_struct *arg) need_order = 1; wq = work->wq; + thresh_exec_hook(wq); work->func(work); if (need_order) { set_bit(WORK_DONE_BIT, &work->flags); @@ -884,6 +974,7 @@ static inline void __btrfs_queue_work(struct __btrfs_workqueue_struct *wq, unsigned long flags; work->wq = wq; + thresh_queue_hook(wq); if (work->ordered_func) { spin_lock_irqsave(&wq->list_lock, flags); list_add_tail(&work->ordered_list, &wq->ordered_list); @@ -922,9 +1013,9 @@ void btrfs_destroy_workqueue(struct btrfs_workqueue_struct *wq) void btrfs_workqueue_set_max(struct btrfs_workqueue_struct *wq, int max) { - workqueue_set_max_active(wq->normal->normal_wq, max); + wq->normal->max_active = max; if (wq->high) - workqueue_set_max_active(wq->high->normal_wq, max); + wq->high->max_active = max; } void btrfs_set_work_high_priority(struct btrfs_work_struct *work) |