From c6dd6ea55758cf403bdc07a51a06c2a1d474f906 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 20 Aug 2015 09:30:39 +0800 Subject: [PATCH] btrfs: async_thread: Fix workqueue 'max_active' value when initializing At initializing time, for threshold-able workqueue, it's max_active of kernel workqueue should be 1 and grow if it hits threshold. But due to the bad naming, there is both 'max_active' for kernel workqueue and btrfs workqueue. So wrong value is given at workqueue initialization. This patch fixes it, and to avoid further misunderstanding, change the member name of btrfs_workqueue to 'current_active' and 'limit_active'. Also corresponding comment is added for readability. Reported-by: Alex Lyakas Signed-off-by: Qu Wenruo Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 57 +++++++++++++++++++++++++++++-------------------- fs/btrfs/async-thread.h | 2 +- 2 files changed, 35 insertions(+), 24 deletions(-) diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 1ce06c84..3e36e4a 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -42,8 +42,14 @@ struct __btrfs_workqueue { /* Thresholding related variants */ atomic_t pending; - int max_active; - int current_max; + + /* Up limit of concurrency workers */ + int limit_active; + + /* Current number of concurrency workers */ + int current_active; + + /* Threshold to change current_active */ int thresh; unsigned int count; spinlock_t thres_lock; @@ -88,7 +94,7 @@ BTRFS_WORK_HELPER(scrubnc_helper); BTRFS_WORK_HELPER(scrubparity_helper); static struct __btrfs_workqueue * -__btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active, +__btrfs_alloc_workqueue(const char *name, unsigned int flags, int limit_active, int thresh) { struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS); @@ -96,26 +102,31 @@ __btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active, if (!ret) return NULL; - ret->max_active = max_active; + ret->limit_active = limit_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->current_active = limit_active; ret->thresh = NO_THRESHOLD; } else { - ret->current_max = 1; + /* + * For threshold-able wq, let its concurrency grow on demand. + * Use minimal max_active at alloc time to reduce resource + * usage. + */ + ret->current_active = 1; ret->thresh = thresh; } if (flags & WQ_HIGHPRI) ret->normal_wq = alloc_workqueue("%s-%s-high", flags, - ret->max_active, - "btrfs", name); + ret->current_active, "btrfs", + name); else ret->normal_wq = alloc_workqueue("%s-%s", flags, - ret->max_active, "btrfs", + ret->current_active, "btrfs", name); if (!ret->normal_wq) { kfree(ret); @@ -134,7 +145,7 @@ __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq); struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name, unsigned int flags, - int max_active, + int limit_active, int thresh) { struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS); @@ -143,14 +154,14 @@ struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name, return NULL; ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI, - max_active, thresh); + limit_active, thresh); if (!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, limit_active, thresh); if (!ret->high) { __btrfs_destroy_workqueue(ret->normal); @@ -180,7 +191,7 @@ static inline void thresh_queue_hook(struct __btrfs_workqueue *wq) */ static inline void thresh_exec_hook(struct __btrfs_workqueue *wq) { - int new_max_active; + int new_current_active; long pending; int need_change = 0; @@ -197,7 +208,7 @@ static inline void thresh_exec_hook(struct __btrfs_workqueue *wq) wq->count %= (wq->thresh / 4); if (!wq->count) goto out; - new_max_active = wq->current_max; + new_current_active = wq->current_active; /* * pending may be changed later, but it's OK since we really @@ -205,19 +216,19 @@ static inline void thresh_exec_hook(struct __btrfs_workqueue *wq) */ pending = atomic_read(&wq->pending); if (pending > wq->thresh) - new_max_active++; + new_current_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) { + new_current_active--; + new_current_active = clamp_val(new_current_active, 1, wq->limit_active); + if (new_current_active != wq->current_active) { need_change = 1; - wq->current_max = new_max_active; + wq->current_active = new_current_active; } out: spin_unlock(&wq->thres_lock); if (need_change) { - workqueue_set_max_active(wq->normal_wq, wq->current_max); + workqueue_set_max_active(wq->normal_wq, wq->current_active); } } @@ -351,13 +362,13 @@ void btrfs_destroy_workqueue(struct btrfs_workqueue *wq) kfree(wq); } -void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max) +void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active) { if (!wq) return; - wq->normal->max_active = max; + wq->normal->limit_active = limit_active; if (wq->high) - wq->high->max_active = max; + wq->high->limit_active = limit_active; } void btrfs_set_work_high_priority(struct btrfs_work *work) diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index b0b093b..ad4d064 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -69,7 +69,7 @@ BTRFS_WORK_HELPER_PROTO(scrubparity_helper); struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name, unsigned int flags, - int max_active, + int limit_active, int thresh); void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t helper, btrfs_func_t func, -- 2.7.4