| /* |
| * CFQ, or complete fairness queueing, disk scheduler. |
| * |
| * Based on ideas from a previously unfinished io |
| * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. |
| * |
| * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
| */ |
| #include <linux/module.h> |
| #include <linux/blkdev.h> |
| #include <linux/elevator.h> |
| #include <linux/rbtree.h> |
| #include <linux/ioprio.h> |
| #include <linux/blktrace_api.h> |
| |
| /* |
| * tunables |
| */ |
| /* max queue in one round of service */ |
| static const int cfq_quantum = 4; |
| static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
| /* maximum backwards seek, in KiB */ |
| static const int cfq_back_max = 16 * 1024; |
| /* penalty of a backwards seek */ |
| static const int cfq_back_penalty = 2; |
| static const int cfq_slice_sync = HZ / 10; |
| static int cfq_slice_async = HZ / 25; |
| static const int cfq_slice_async_rq = 2; |
| static int cfq_slice_idle = HZ / 125; |
| |
| /* |
| * offset from end of service tree |
| */ |
| #define CFQ_IDLE_DELAY (HZ / 5) |
| |
| /* |
| * below this threshold, we consider thinktime immediate |
| */ |
| #define CFQ_MIN_TT (2) |
| |
| #define CFQ_SLICE_SCALE (5) |
| #define CFQ_HW_QUEUE_MIN (5) |
| |
| #define RQ_CIC(rq) \ |
| ((struct cfq_io_context *) (rq)->elevator_private) |
| #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) |
| |
| static struct kmem_cache *cfq_pool; |
| static struct kmem_cache *cfq_ioc_pool; |
| |
| static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
| static struct completion *ioc_gone; |
| static DEFINE_SPINLOCK(ioc_gone_lock); |
| |
| #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
| #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) |
| #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
| |
| #define sample_valid(samples) ((samples) > 80) |
| |
| /* |
| * Most of our rbtree usage is for sorting with min extraction, so |
| * if we cache the leftmost node we don't have to walk down the tree |
| * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should |
| * move this into the elevator for the rq sorting as well. |
| */ |
| struct cfq_rb_root { |
| struct rb_root rb; |
| struct rb_node *left; |
| }; |
| #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, } |
| |
| /* |
| * Per process-grouping structure |
| */ |
| struct cfq_queue { |
| /* reference count */ |
| atomic_t ref; |
| /* various state flags, see below */ |
| unsigned int flags; |
| /* parent cfq_data */ |
| struct cfq_data *cfqd; |
| /* service_tree member */ |
| struct rb_node rb_node; |
| /* service_tree key */ |
| unsigned long rb_key; |
| /* prio tree member */ |
| struct rb_node p_node; |
| /* prio tree root we belong to, if any */ |
| struct rb_root *p_root; |
| /* sorted list of pending requests */ |
| struct rb_root sort_list; |
| /* if fifo isn't expired, next request to serve */ |
| struct request *next_rq; |
| /* requests queued in sort_list */ |
| int queued[2]; |
| /* currently allocated requests */ |
| int allocated[2]; |
| /* fifo list of requests in sort_list */ |
| struct list_head fifo; |
| |
| unsigned long slice_end; |
| long slice_resid; |
| unsigned int slice_dispatch; |
| |
| /* pending metadata requests */ |
| int meta_pending; |
| /* number of requests that are on the dispatch list or inside driver */ |
| int dispatched; |
| |
| /* io prio of this group */ |
| unsigned short ioprio, org_ioprio; |
| unsigned short ioprio_class, org_ioprio_class; |
| |
| pid_t pid; |
| }; |
| |
| /* |
| * Per block device queue structure |
| */ |
| struct cfq_data { |
| struct request_queue *queue; |
| |
| /* |
| * rr list of queues with requests and the count of them |
| */ |
| struct cfq_rb_root service_tree; |
| |
| /* |
| * Each priority tree is sorted by next_request position. These |
| * trees are used when determining if two or more queues are |
| * interleaving requests (see cfq_close_cooperator). |
| */ |
| struct rb_root prio_trees[CFQ_PRIO_LISTS]; |
| |
| unsigned int busy_queues; |
| |
| int rq_in_driver[2]; |
| int sync_flight; |
| |
| /* |
| * queue-depth detection |
| */ |
| int rq_queued; |
| int hw_tag; |
| int hw_tag_samples; |
| int rq_in_driver_peak; |
| |
| /* |
| * idle window management |
| */ |
| struct timer_list idle_slice_timer; |
| struct delayed_work unplug_work; |
| |
| struct cfq_queue *active_queue; |
| struct cfq_io_context *active_cic; |
| |
| /* |
| * async queue for each priority case |
| */ |
| struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; |
| struct cfq_queue *async_idle_cfqq; |
| |
| sector_t last_position; |
| |
| /* |
| * tunables, see top of file |
| */ |
| unsigned int cfq_quantum; |
| unsigned int cfq_fifo_expire[2]; |
| unsigned int cfq_back_penalty; |
| unsigned int cfq_back_max; |
| unsigned int cfq_slice[2]; |
| unsigned int cfq_slice_async_rq; |
| unsigned int cfq_slice_idle; |
| unsigned int cfq_latency; |
| |
| struct list_head cic_list; |
| |
| /* |
| * Fallback dummy cfqq for extreme OOM conditions |
| */ |
| struct cfq_queue oom_cfqq; |
| |
| unsigned long last_end_sync_rq; |
| }; |
| |
| enum cfqq_state_flags { |
| CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
| CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ |
| CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
| CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
| CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
| CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ |
| CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ |
| CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
| CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
| CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */ |
| }; |
| |
| #define CFQ_CFQQ_FNS(name) \ |
| static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ |
| { \ |
| (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
| } \ |
| static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ |
| { \ |
| (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
| } \ |
| static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ |
| { \ |
| return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
| } |
| |
| CFQ_CFQQ_FNS(on_rr); |
| CFQ_CFQQ_FNS(wait_request); |
| CFQ_CFQQ_FNS(must_dispatch); |
| CFQ_CFQQ_FNS(must_alloc_slice); |
| CFQ_CFQQ_FNS(fifo_expire); |
| CFQ_CFQQ_FNS(idle_window); |
| CFQ_CFQQ_FNS(prio_changed); |
| CFQ_CFQQ_FNS(slice_new); |
| CFQ_CFQQ_FNS(sync); |
| CFQ_CFQQ_FNS(coop); |
| #undef CFQ_CFQQ_FNS |
| |
| #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) |
| #define cfq_log(cfqd, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) |
| |
| static void cfq_dispatch_insert(struct request_queue *, struct request *); |
| static struct cfq_queue *cfq_get_queue(struct cfq_data *, int, |
| struct io_context *, gfp_t); |
| static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
| struct io_context *); |
| |
| static inline int rq_in_driver(struct cfq_data *cfqd) |
| { |
| return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; |
| } |
| |
| static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
| int is_sync) |
| { |
| return cic->cfqq[!!is_sync]; |
| } |
| |
| static inline void cic_set_cfqq(struct cfq_io_context *cic, |
| struct cfq_queue *cfqq, int is_sync) |
| { |
| cic->cfqq[!!is_sync] = cfqq; |
| } |
| |
| /* |
| * We regard a request as SYNC, if it's either a read or has the SYNC bit |
| * set (in which case it could also be direct WRITE). |
| */ |
| static inline int cfq_bio_sync(struct bio *bio) |
| { |
| if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO)) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* |
| * scheduler run of queue, if there are requests pending and no one in the |
| * driver that will restart queueing |
| */ |
| static inline void cfq_schedule_dispatch(struct cfq_data *cfqd, |
| unsigned long delay) |
| { |
| if (cfqd->busy_queues) { |
| cfq_log(cfqd, "schedule dispatch"); |
| kblockd_schedule_delayed_work(cfqd->queue, &cfqd->unplug_work, |
| delay); |
| } |
| } |
| |
| static int cfq_queue_empty(struct request_queue *q) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| |
| return !cfqd->busy_queues; |
| } |
| |
| /* |
| * Scale schedule slice based on io priority. Use the sync time slice only |
| * if a queue is marked sync and has sync io queued. A sync queue with async |
| * io only, should not get full sync slice length. |
| */ |
| static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync, |
| unsigned short prio) |
| { |
| const int base_slice = cfqd->cfq_slice[sync]; |
| |
| WARN_ON(prio >= IOPRIO_BE_NR); |
| |
| return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); |
| } |
| |
| static inline int |
| cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); |
| } |
| |
| static inline void |
| cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
| cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
| } |
| |
| /* |
| * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end |
| * isn't valid until the first request from the dispatch is activated |
| * and the slice time set. |
| */ |
| static inline int cfq_slice_used(struct cfq_queue *cfqq) |
| { |
| if (cfq_cfqq_slice_new(cfqq)) |
| return 0; |
| if (time_before(jiffies, cfqq->slice_end)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
| * We choose the request that is closest to the head right now. Distance |
| * behind the head is penalized and only allowed to a certain extent. |
| */ |
| static struct request * |
| cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) |
| { |
| sector_t last, s1, s2, d1 = 0, d2 = 0; |
| unsigned long back_max; |
| #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
| #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ |
| unsigned wrap = 0; /* bit mask: requests behind the disk head? */ |
| |
| if (rq1 == NULL || rq1 == rq2) |
| return rq2; |
| if (rq2 == NULL) |
| return rq1; |
| |
| if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
| return rq1; |
| else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) |
| return rq2; |
| if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
| return rq1; |
| else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) |
| return rq2; |
| |
| s1 = blk_rq_pos(rq1); |
| s2 = blk_rq_pos(rq2); |
| |
| last = cfqd->last_position; |
| |
| /* |
| * by definition, 1KiB is 2 sectors |
| */ |
| back_max = cfqd->cfq_back_max * 2; |
| |
| /* |
| * Strict one way elevator _except_ in the case where we allow |
| * short backward seeks which are biased as twice the cost of a |
| * similar forward seek. |
| */ |
| if (s1 >= last) |
| d1 = s1 - last; |
| else if (s1 + back_max >= last) |
| d1 = (last - s1) * cfqd->cfq_back_penalty; |
| else |
| wrap |= CFQ_RQ1_WRAP; |
| |
| if (s2 >= last) |
| d2 = s2 - last; |
| else if (s2 + back_max >= last) |
| d2 = (last - s2) * cfqd->cfq_back_penalty; |
| else |
| wrap |= CFQ_RQ2_WRAP; |
| |
| /* Found required data */ |
| |
| /* |
| * By doing switch() on the bit mask "wrap" we avoid having to |
| * check two variables for all permutations: --> faster! |
| */ |
| switch (wrap) { |
| case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
| if (d1 < d2) |
| return rq1; |
| else if (d2 < d1) |
| return rq2; |
| else { |
| if (s1 >= s2) |
| return rq1; |
| else |
| return rq2; |
| } |
| |
| case CFQ_RQ2_WRAP: |
| return rq1; |
| case CFQ_RQ1_WRAP: |
| return rq2; |
| case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ |
| default: |
| /* |
| * Since both rqs are wrapped, |
| * start with the one that's further behind head |
| * (--> only *one* back seek required), |
| * since back seek takes more time than forward. |
| */ |
| if (s1 <= s2) |
| return rq1; |
| else |
| return rq2; |
| } |
| } |
| |
| /* |
| * The below is leftmost cache rbtree addon |
| */ |
| static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
| { |
| if (!root->left) |
| root->left = rb_first(&root->rb); |
| |
| if (root->left) |
| return rb_entry(root->left, struct cfq_queue, rb_node); |
| |
| return NULL; |
| } |
| |
| static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
| { |
| rb_erase(n, root); |
| RB_CLEAR_NODE(n); |
| } |
| |
| static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
| { |
| if (root->left == n) |
| root->left = NULL; |
| rb_erase_init(n, &root->rb); |
| } |
| |
| /* |
| * would be nice to take fifo expire time into account as well |
| */ |
| static struct request * |
| cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *last) |
| { |
| struct rb_node *rbnext = rb_next(&last->rb_node); |
| struct rb_node *rbprev = rb_prev(&last->rb_node); |
| struct request *next = NULL, *prev = NULL; |
| |
| BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
| |
| if (rbprev) |
| prev = rb_entry_rq(rbprev); |
| |
| if (rbnext) |
| next = rb_entry_rq(rbnext); |
| else { |
| rbnext = rb_first(&cfqq->sort_list); |
| if (rbnext && rbnext != &last->rb_node) |
| next = rb_entry_rq(rbnext); |
| } |
| |
| return cfq_choose_req(cfqd, next, prev); |
| } |
| |
| static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| /* |
| * just an approximation, should be ok. |
| */ |
| return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
| cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); |
| } |
| |
| /* |
| * The cfqd->service_tree holds all pending cfq_queue's that have |
| * requests waiting to be processed. It is sorted in the order that |
| * we will service the queues. |
| */ |
| static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| int add_front) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *__cfqq; |
| unsigned long rb_key; |
| int left; |
| |
| if (cfq_class_idle(cfqq)) { |
| rb_key = CFQ_IDLE_DELAY; |
| parent = rb_last(&cfqd->service_tree.rb); |
| if (parent && parent != &cfqq->rb_node) { |
| __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| rb_key += __cfqq->rb_key; |
| } else |
| rb_key += jiffies; |
| } else if (!add_front) { |
| rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
| rb_key += cfqq->slice_resid; |
| cfqq->slice_resid = 0; |
| } else |
| rb_key = 0; |
| |
| if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
| /* |
| * same position, nothing more to do |
| */ |
| if (rb_key == cfqq->rb_key) |
| return; |
| |
| cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
| } |
| |
| left = 1; |
| parent = NULL; |
| p = &cfqd->service_tree.rb.rb_node; |
| while (*p) { |
| struct rb_node **n; |
| |
| parent = *p; |
| __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| |
| /* |
| * sort RT queues first, we always want to give |
| * preference to them. IDLE queues goes to the back. |
| * after that, sort on the next service time. |
| */ |
| if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) |
| n = &(*p)->rb_left; |
| else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) |
| n = &(*p)->rb_right; |
| else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) |
| n = &(*p)->rb_left; |
| else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) |
| n = &(*p)->rb_right; |
| else if (rb_key < __cfqq->rb_key) |
| n = &(*p)->rb_left; |
| else |
| n = &(*p)->rb_right; |
| |
| if (n == &(*p)->rb_right) |
| left = 0; |
| |
| p = n; |
| } |
| |
| if (left) |
| cfqd->service_tree.left = &cfqq->rb_node; |
| |
| cfqq->rb_key = rb_key; |
| rb_link_node(&cfqq->rb_node, parent, p); |
| rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); |
| } |
| |
| static struct cfq_queue * |
| cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
| sector_t sector, struct rb_node **ret_parent, |
| struct rb_node ***rb_link) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *cfqq = NULL; |
| |
| parent = NULL; |
| p = &root->rb_node; |
| while (*p) { |
| struct rb_node **n; |
| |
| parent = *p; |
| cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| |
| /* |
| * Sort strictly based on sector. Smallest to the left, |
| * largest to the right. |
| */ |
| if (sector > blk_rq_pos(cfqq->next_rq)) |
| n = &(*p)->rb_right; |
| else if (sector < blk_rq_pos(cfqq->next_rq)) |
| n = &(*p)->rb_left; |
| else |
| break; |
| p = n; |
| cfqq = NULL; |
| } |
| |
| *ret_parent = parent; |
| if (rb_link) |
| *rb_link = p; |
| return cfqq; |
| } |
| |
| static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *__cfqq; |
| |
| if (cfqq->p_root) { |
| rb_erase(&cfqq->p_node, cfqq->p_root); |
| cfqq->p_root = NULL; |
| } |
| |
| if (cfq_class_idle(cfqq)) |
| return; |
| if (!cfqq->next_rq) |
| return; |
| |
| cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
| __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
| blk_rq_pos(cfqq->next_rq), &parent, &p); |
| if (!__cfqq) { |
| rb_link_node(&cfqq->p_node, parent, p); |
| rb_insert_color(&cfqq->p_node, cfqq->p_root); |
| } else |
| cfqq->p_root = NULL; |
| } |
| |
| /* |
| * Update cfqq's position in the service tree. |
| */ |
| static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| /* |
| * Resorting requires the cfqq to be on the RR list already. |
| */ |
| if (cfq_cfqq_on_rr(cfqq)) { |
| cfq_service_tree_add(cfqd, cfqq, 0); |
| cfq_prio_tree_add(cfqd, cfqq); |
| } |
| } |
| |
| /* |
| * add to busy list of queues for service, trying to be fair in ordering |
| * the pending list according to last request service |
| */ |
| static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
| BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| cfq_mark_cfqq_on_rr(cfqq); |
| cfqd->busy_queues++; |
| |
| cfq_resort_rr_list(cfqd, cfqq); |
| } |
| |
| /* |
| * Called when the cfqq no longer has requests pending, remove it from |
| * the service tree. |
| */ |
| static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
| BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| cfq_clear_cfqq_on_rr(cfqq); |
| |
| if (!RB_EMPTY_NODE(&cfqq->rb_node)) |
| cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
| if (cfqq->p_root) { |
| rb_erase(&cfqq->p_node, cfqq->p_root); |
| cfqq->p_root = NULL; |
| } |
| |
| BUG_ON(!cfqd->busy_queues); |
| cfqd->busy_queues--; |
| } |
| |
| /* |
| * rb tree support functions |
| */ |
| static void cfq_del_rq_rb(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| struct cfq_data *cfqd = cfqq->cfqd; |
| const int sync = rq_is_sync(rq); |
| |
| BUG_ON(!cfqq->queued[sync]); |
| cfqq->queued[sync]--; |
| |
| elv_rb_del(&cfqq->sort_list, rq); |
| |
| if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
| cfq_del_cfqq_rr(cfqd, cfqq); |
| } |
| |
| static void cfq_add_rq_rb(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| struct cfq_data *cfqd = cfqq->cfqd; |
| struct request *__alias, *prev; |
| |
| cfqq->queued[rq_is_sync(rq)]++; |
| |
| /* |
| * looks a little odd, but the first insert might return an alias. |
| * if that happens, put the alias on the dispatch list |
| */ |
| while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
| cfq_dispatch_insert(cfqd->queue, __alias); |
| |
| if (!cfq_cfqq_on_rr(cfqq)) |
| cfq_add_cfqq_rr(cfqd, cfqq); |
| |
| /* |
| * check if this request is a better next-serve candidate |
| */ |
| prev = cfqq->next_rq; |
| cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); |
| |
| /* |
| * adjust priority tree position, if ->next_rq changes |
| */ |
| if (prev != cfqq->next_rq) |
| cfq_prio_tree_add(cfqd, cfqq); |
| |
| BUG_ON(!cfqq->next_rq); |
| } |
| |
| static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
| { |
| elv_rb_del(&cfqq->sort_list, rq); |
| cfqq->queued[rq_is_sync(rq)]--; |
| cfq_add_rq_rb(rq); |
| } |
| |
| static struct request * |
| cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) |
| { |
| struct task_struct *tsk = current; |
| struct cfq_io_context *cic; |
| struct cfq_queue *cfqq; |
| |
| cic = cfq_cic_lookup(cfqd, tsk->io_context); |
| if (!cic) |
| return NULL; |
| |
| cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| if (cfqq) { |
| sector_t sector = bio->bi_sector + bio_sectors(bio); |
| |
| return elv_rb_find(&cfqq->sort_list, sector); |
| } |
| |
| return NULL; |
| } |
| |
| static void cfq_activate_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| |
| cfqd->rq_in_driver[rq_is_sync(rq)]++; |
| cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
| rq_in_driver(cfqd)); |
| |
| cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| } |
| |
| static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| const int sync = rq_is_sync(rq); |
| |
| WARN_ON(!cfqd->rq_in_driver[sync]); |
| cfqd->rq_in_driver[sync]--; |
| cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
| rq_in_driver(cfqd)); |
| } |
| |
| static void cfq_remove_request(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| if (cfqq->next_rq == rq) |
| cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); |
| |
| list_del_init(&rq->queuelist); |
| cfq_del_rq_rb(rq); |
| |
| cfqq->cfqd->rq_queued--; |
| if (rq_is_meta(rq)) { |
| WARN_ON(!cfqq->meta_pending); |
| cfqq->meta_pending--; |
| } |
| } |
| |
| static int cfq_merge(struct request_queue *q, struct request **req, |
| struct bio *bio) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct request *__rq; |
| |
| __rq = cfq_find_rq_fmerge(cfqd, bio); |
| if (__rq && elv_rq_merge_ok(__rq, bio)) { |
| *req = __rq; |
| return ELEVATOR_FRONT_MERGE; |
| } |
| |
| return ELEVATOR_NO_MERGE; |
| } |
| |
| static void cfq_merged_request(struct request_queue *q, struct request *req, |
| int type) |
| { |
| if (type == ELEVATOR_FRONT_MERGE) { |
| struct cfq_queue *cfqq = RQ_CFQQ(req); |
| |
| cfq_reposition_rq_rb(cfqq, req); |
| } |
| } |
| |
| static void |
| cfq_merged_requests(struct request_queue *q, struct request *rq, |
| struct request *next) |
| { |
| /* |
| * reposition in fifo if next is older than rq |
| */ |
| if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && |
| time_before(next->start_time, rq->start_time)) |
| list_move(&rq->queuelist, &next->queuelist); |
| |
| cfq_remove_request(next); |
| } |
| |
| static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
| struct bio *bio) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_io_context *cic; |
| struct cfq_queue *cfqq; |
| |
| /* |
| * Disallow merge of a sync bio into an async request. |
| */ |
| if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
| return 0; |
| |
| /* |
| * Lookup the cfqq that this bio will be queued with. Allow |
| * merge only if rq is queued there. |
| */ |
| cic = cfq_cic_lookup(cfqd, current->io_context); |
| if (!cic) |
| return 0; |
| |
| cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| if (cfqq == RQ_CFQQ(rq)) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void __cfq_set_active_queue(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| if (cfqq) { |
| cfq_log_cfqq(cfqd, cfqq, "set_active"); |
| cfqq->slice_end = 0; |
| cfqq->slice_dispatch = 0; |
| |
| cfq_clear_cfqq_wait_request(cfqq); |
| cfq_clear_cfqq_must_dispatch(cfqq); |
| cfq_clear_cfqq_must_alloc_slice(cfqq); |
| cfq_clear_cfqq_fifo_expire(cfqq); |
| cfq_mark_cfqq_slice_new(cfqq); |
| |
| del_timer(&cfqd->idle_slice_timer); |
| } |
| |
| cfqd->active_queue = cfqq; |
| } |
| |
| /* |
| * current cfqq expired its slice (or was too idle), select new one |
| */ |
| static void |
| __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| int timed_out) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
| |
| if (cfq_cfqq_wait_request(cfqq)) |
| del_timer(&cfqd->idle_slice_timer); |
| |
| cfq_clear_cfqq_wait_request(cfqq); |
| |
| /* |
| * store what was left of this slice, if the queue idled/timed out |
| */ |
| if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
| cfqq->slice_resid = cfqq->slice_end - jiffies; |
| cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
| } |
| |
| cfq_resort_rr_list(cfqd, cfqq); |
| |
| if (cfqq == cfqd->active_queue) |
| cfqd->active_queue = NULL; |
| |
| if (cfqd->active_cic) { |
| put_io_context(cfqd->active_cic->ioc); |
| cfqd->active_cic = NULL; |
| } |
| } |
| |
| static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out) |
| { |
| struct cfq_queue *cfqq = cfqd->active_queue; |
| |
| if (cfqq) |
| __cfq_slice_expired(cfqd, cfqq, timed_out); |
| } |
| |
| /* |
| * Get next queue for service. Unless we have a queue preemption, |
| * we'll simply select the first cfqq in the service tree. |
| */ |
| static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
| { |
| if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) |
| return NULL; |
| |
| return cfq_rb_first(&cfqd->service_tree); |
| } |
| |
| /* |
| * Get and set a new active queue for service. |
| */ |
| static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| if (!cfqq) { |
| cfqq = cfq_get_next_queue(cfqd); |
| if (cfqq) |
| cfq_clear_cfqq_coop(cfqq); |
| } |
| |
| __cfq_set_active_queue(cfqd, cfqq); |
| return cfqq; |
| } |
| |
| static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
| struct request *rq) |
| { |
| if (blk_rq_pos(rq) >= cfqd->last_position) |
| return blk_rq_pos(rq) - cfqd->last_position; |
| else |
| return cfqd->last_position - blk_rq_pos(rq); |
| } |
| |
| #define CIC_SEEK_THR 8 * 1024 |
| #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR) |
| |
| static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) |
| { |
| struct cfq_io_context *cic = cfqd->active_cic; |
| sector_t sdist = cic->seek_mean; |
| |
| if (!sample_valid(cic->seek_samples)) |
| sdist = CIC_SEEK_THR; |
| |
| return cfq_dist_from_last(cfqd, rq) <= sdist; |
| } |
| |
| static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
| struct cfq_queue *cur_cfqq) |
| { |
| struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
| struct rb_node *parent, *node; |
| struct cfq_queue *__cfqq; |
| sector_t sector = cfqd->last_position; |
| |
| if (RB_EMPTY_ROOT(root)) |
| return NULL; |
| |
| /* |
| * First, if we find a request starting at the end of the last |
| * request, choose it. |
| */ |
| __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
| if (__cfqq) |
| return __cfqq; |
| |
| /* |
| * If the exact sector wasn't found, the parent of the NULL leaf |
| * will contain the closest sector. |
| */ |
| __cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| if (cfq_rq_close(cfqd, __cfqq->next_rq)) |
| return __cfqq; |
| |
| if (blk_rq_pos(__cfqq->next_rq) < sector) |
| node = rb_next(&__cfqq->p_node); |
| else |
| node = rb_prev(&__cfqq->p_node); |
| if (!node) |
| return NULL; |
| |
| __cfqq = rb_entry(node, struct cfq_queue, p_node); |
| if (cfq_rq_close(cfqd, __cfqq->next_rq)) |
| return __cfqq; |
| |
| return NULL; |
| } |
| |
| /* |
| * cfqd - obvious |
| * cur_cfqq - passed in so that we don't decide that the current queue is |
| * closely cooperating with itself. |
| * |
| * So, basically we're assuming that that cur_cfqq has dispatched at least |
| * one request, and that cfqd->last_position reflects a position on the disk |
| * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid |
| * assumption. |
| */ |
| static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, |
| struct cfq_queue *cur_cfqq, |
| int probe) |
| { |
| struct cfq_queue *cfqq; |
| |
| /* |
| * A valid cfq_io_context is necessary to compare requests against |
| * the seek_mean of the current cfqq. |
| */ |
| if (!cfqd->active_cic) |
| return NULL; |
| |
| /* |
| * We should notice if some of the queues are cooperating, eg |
| * working closely on the same area of the disk. In that case, |
| * we can group them together and don't waste time idling. |
| */ |
| cfqq = cfqq_close(cfqd, cur_cfqq); |
| if (!cfqq) |
| return NULL; |
| |
| if (cfq_cfqq_coop(cfqq)) |
| return NULL; |
| |
| if (!probe) |
| cfq_mark_cfqq_coop(cfqq); |
| return cfqq; |
| } |
| |
| static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq = cfqd->active_queue; |
| struct cfq_io_context *cic; |
| unsigned long sl; |
| |
| /* |
| * SSD device without seek penalty, disable idling. But only do so |
| * for devices that support queuing, otherwise we still have a problem |
| * with sync vs async workloads. |
| */ |
| if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
| return; |
| |
| WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
| WARN_ON(cfq_cfqq_slice_new(cfqq)); |
| |
| /* |
| * idle is disabled, either manually or by past process history |
| */ |
| if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
| return; |
| |
| /* |
| * still requests with the driver, don't idle |
| */ |
| if (rq_in_driver(cfqd)) |
| return; |
| |
| /* |
| * task has exited, don't wait |
| */ |
| cic = cfqd->active_cic; |
| if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
| return; |
| |
| cfq_mark_cfqq_wait_request(cfqq); |
| |
| /* |
| * we don't want to idle for seeks, but we do want to allow |
| * fair distribution of slice time for a process doing back-to-back |
| * seeks. so allow a little bit of time for him to submit a new rq |
| */ |
| sl = cfqd->cfq_slice_idle; |
| if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
| sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
| |
| mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
| cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
| } |
| |
| /* |
| * Move request from internal lists to the request queue dispatch list. |
| */ |
| static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
| |
| cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
| cfq_remove_request(rq); |
| cfqq->dispatched++; |
| elv_dispatch_sort(q, rq); |
| |
| if (cfq_cfqq_sync(cfqq)) |
| cfqd->sync_flight++; |
| } |
| |
| /* |
| * return expired entry, or NULL to just start from scratch in rbtree |
| */ |
| static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
| { |
| struct cfq_data *cfqd = cfqq->cfqd; |
| struct request *rq; |
| int fifo; |
| |
| if (cfq_cfqq_fifo_expire(cfqq)) |
| return NULL; |
| |
| cfq_mark_cfqq_fifo_expire(cfqq); |
| |
| if (list_empty(&cfqq->fifo)) |
| return NULL; |
| |
| fifo = cfq_cfqq_sync(cfqq); |
| rq = rq_entry_fifo(cfqq->fifo.next); |
| |
| if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) |
| rq = NULL; |
| |
| cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq); |
| return rq; |
| } |
| |
| static inline int |
| cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| const int base_rq = cfqd->cfq_slice_async_rq; |
| |
| WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
| |
| return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
| } |
| |
| /* |
| * Select a queue for service. If we have a current active queue, |
| * check whether to continue servicing it, or retrieve and set a new one. |
| */ |
| static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq, *new_cfqq = NULL; |
| |
| cfqq = cfqd->active_queue; |
| if (!cfqq) |
| goto new_queue; |
| |
| /* |
| * The active queue has run out of time, expire it and select new. |
| */ |
| if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
| goto expire; |
| |
| /* |
| * The active queue has requests and isn't expired, allow it to |
| * dispatch. |
| */ |
| if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
| goto keep_queue; |
| |
| /* |
| * If another queue has a request waiting within our mean seek |
| * distance, let it run. The expire code will check for close |
| * cooperators and put the close queue at the front of the service |
| * tree. |
| */ |
| new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0); |
| if (new_cfqq) |
| goto expire; |
| |
| /* |
| * No requests pending. If the active queue still has requests in |
| * flight or is idling for a new request, allow either of these |
| * conditions to happen (or time out) before selecting a new queue. |
| */ |
| if (timer_pending(&cfqd->idle_slice_timer) || |
| (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { |
| cfqq = NULL; |
| goto keep_queue; |
| } |
| |
| expire: |
| cfq_slice_expired(cfqd, 0); |
| new_queue: |
| cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
| keep_queue: |
| return cfqq; |
| } |
| |
| static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
| { |
| int dispatched = 0; |
| |
| while (cfqq->next_rq) { |
| cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); |
| dispatched++; |
| } |
| |
| BUG_ON(!list_empty(&cfqq->fifo)); |
| return dispatched; |
| } |
| |
| /* |
| * Drain our current requests. Used for barriers and when switching |
| * io schedulers on-the-fly. |
| */ |
| static int cfq_forced_dispatch(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq; |
| int dispatched = 0; |
| |
| while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL) |
| dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
| |
| cfq_slice_expired(cfqd, 0); |
| |
| BUG_ON(cfqd->busy_queues); |
| |
| cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
| return dispatched; |
| } |
| |
| /* |
| * Dispatch a request from cfqq, moving them to the request queue |
| * dispatch list. |
| */ |
| static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| struct request *rq; |
| |
| BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
| |
| /* |
| * follow expired path, else get first next available |
| */ |
| rq = cfq_check_fifo(cfqq); |
| if (!rq) |
| rq = cfqq->next_rq; |
| |
| /* |
| * insert request into driver dispatch list |
| */ |
| cfq_dispatch_insert(cfqd->queue, rq); |
| |
| if (!cfqd->active_cic) { |
| struct cfq_io_context *cic = RQ_CIC(rq); |
| |
| atomic_long_inc(&cic->ioc->refcount); |
| cfqd->active_cic = cic; |
| } |
| } |
| |
| /* |
| * Find the cfqq that we need to service and move a request from that to the |
| * dispatch list |
| */ |
| static int cfq_dispatch_requests(struct request_queue *q, int force) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_queue *cfqq; |
| unsigned int max_dispatch; |
| |
| if (!cfqd->busy_queues) |
| return 0; |
| |
| if (unlikely(force)) |
| return cfq_forced_dispatch(cfqd); |
| |
| cfqq = cfq_select_queue(cfqd); |
| if (!cfqq) |
| return 0; |
| |
| /* |
| * Drain async requests before we start sync IO |
| */ |
| if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) |
| return 0; |
| |
| /* |
| * If this is an async queue and we have sync IO in flight, let it wait |
| */ |
| if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) |
| return 0; |
| |
| max_dispatch = cfqd->cfq_quantum; |
| if (cfq_class_idle(cfqq)) |
| max_dispatch = 1; |
| |
| /* |
| * Does this cfqq already have too much IO in flight? |
| */ |
| if (cfqq->dispatched >= max_dispatch) { |
| /* |
| * idle queue must always only have a single IO in flight |
| */ |
| if (cfq_class_idle(cfqq)) |
| return 0; |
| |
| /* |
| * We have other queues, don't allow more IO from this one |
| */ |
| if (cfqd->busy_queues > 1) |
| return 0; |
| |
| /* |
| * Sole queue user, allow bigger slice |
| */ |
| max_dispatch *= 4; |
| } |
| |
| /* |
| * Async queues must wait a bit before being allowed dispatch. |
| * We also ramp up the dispatch depth gradually for async IO, |
| * based on the last sync IO we serviced |
| */ |
| if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
| unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
| unsigned int depth; |
| |
| /* |
| * must wait a bit longer |
| */ |
| if (last_sync < cfq_slice_sync) { |
| cfq_schedule_dispatch(cfqd, cfq_slice_sync - last_sync); |
| return 0; |
| } |
| |
| depth = last_sync / cfq_slice_sync; |
| if (depth < max_dispatch) |
| max_dispatch = depth; |
| } |
| |
| if (cfqq->dispatched >= max_dispatch) |
| return 0; |
| |
| /* |
| * Dispatch a request from this cfqq |
| */ |
| cfq_dispatch_request(cfqd, cfqq); |
| cfqq->slice_dispatch++; |
| cfq_clear_cfqq_must_dispatch(cfqq); |
| |
| /* |
| * expire an async queue immediately if it has used up its slice. idle |
| * queue always expire after 1 dispatch round. |
| */ |
| if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
| cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
| cfq_class_idle(cfqq))) { |
| cfqq->slice_end = jiffies + 1; |
| cfq_slice_expired(cfqd, 0); |
| } |
| |
| cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
| return 1; |
| } |
| |
| /* |
| * task holds one reference to the queue, dropped when task exits. each rq |
| * in-flight on this queue also holds a reference, dropped when rq is freed. |
| * |
| * queue lock must be held here. |
| */ |
| static void cfq_put_queue(struct cfq_queue *cfqq) |
| { |
| struct cfq_data *cfqd = cfqq->cfqd; |
| |
| BUG_ON(atomic_read(&cfqq->ref) <= 0); |
| |
| if (!atomic_dec_and_test(&cfqq->ref)) |
| return; |
| |
| cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
| BUG_ON(rb_first(&cfqq->sort_list)); |
| BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
| BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| |
| if (unlikely(cfqd->active_queue == cfqq)) { |
| __cfq_slice_expired(cfqd, cfqq, 0); |
| cfq_schedule_dispatch(cfqd, 0); |
| } |
| |
| kmem_cache_free(cfq_pool, cfqq); |
| } |
| |
| /* |
| * Must always be called with the rcu_read_lock() held |
| */ |
| static void |
| __call_for_each_cic(struct io_context *ioc, |
| void (*func)(struct io_context *, struct cfq_io_context *)) |
| { |
| struct cfq_io_context *cic; |
| struct hlist_node *n; |
| |
| hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) |
| func(ioc, cic); |
| } |
| |
| /* |
| * Call func for each cic attached to this ioc. |
| */ |
| static void |
| call_for_each_cic(struct io_context *ioc, |
| void (*func)(struct io_context *, struct cfq_io_context *)) |
| { |
| rcu_read_lock(); |
| __call_for_each_cic(ioc, func); |
| rcu_read_unlock(); |
| } |
| |
| static void cfq_cic_free_rcu(struct rcu_head *head) |
| { |
| struct cfq_io_context *cic; |
| |
| cic = container_of(head, struct cfq_io_context, rcu_head); |
| |
| kmem_cache_free(cfq_ioc_pool, cic); |
| elv_ioc_count_dec(cfq_ioc_count); |
| |
| if (ioc_gone) { |
| /* |
| * CFQ scheduler is exiting, grab exit lock and check |
| * the pending io context count. If it hits zero, |
| * complete ioc_gone and set it back to NULL |
| */ |
| spin_lock(&ioc_gone_lock); |
| if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
| complete(ioc_gone); |
| ioc_gone = NULL; |
| } |
| spin_unlock(&ioc_gone_lock); |
| } |
| } |
| |
| static void cfq_cic_free(struct cfq_io_context *cic) |
| { |
| call_rcu(&cic->rcu_head, cfq_cic_free_rcu); |
| } |
| |
| static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) |
| { |
| unsigned long flags; |
| |
| BUG_ON(!cic->dead_key); |
| |
| spin_lock_irqsave(&ioc->lock, flags); |
| radix_tree_delete(&ioc->radix_root, cic->dead_key); |
| hlist_del_rcu(&cic->cic_list); |
| spin_unlock_irqrestore(&ioc->lock, flags); |
| |
| cfq_cic_free(cic); |
| } |
| |
| /* |
| * Must be called with rcu_read_lock() held or preemption otherwise disabled. |
| * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), |
| * and ->trim() which is called with the task lock held |
| */ |
| static void cfq_free_io_context(struct io_context *ioc) |
| { |
| /* |
| * ioc->refcount is zero here, or we are called from elv_unregister(), |
| * so no more cic's are allowed to be linked into this ioc. So it |
| * should be ok to iterate over the known list, we will see all cic's |
| * since no new ones are added. |
| */ |
| __call_for_each_cic(ioc, cic_free_func); |
| } |
| |
| static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| if (unlikely(cfqq == cfqd->active_queue)) { |
| __cfq_slice_expired(cfqd, cfqq, 0); |
| cfq_schedule_dispatch(cfqd, 0); |
| } |
| |
| cfq_put_queue(cfqq); |
| } |
| |
| static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
| struct cfq_io_context *cic) |
| { |
| struct io_context *ioc = cic->ioc; |
| |
| list_del_init(&cic->queue_list); |
| |
| /* |
| * Make sure key == NULL is seen for dead queues |
| */ |
| smp_wmb(); |
| cic->dead_key = (unsigned long) cic->key; |
| cic->key = NULL; |
| |
| if (ioc->ioc_data == cic) |
| rcu_assign_pointer(ioc->ioc_data, NULL); |
| |
| if (cic->cfqq[BLK_RW_ASYNC]) { |
| cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); |
| cic->cfqq[BLK_RW_ASYNC] = NULL; |
| } |
| |
| if (cic->cfqq[BLK_RW_SYNC]) { |
| cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); |
| cic->cfqq[BLK_RW_SYNC] = NULL; |
| } |
| } |
| |
| static void cfq_exit_single_io_context(struct io_context *ioc, |
| struct cfq_io_context *cic) |
| { |
| struct cfq_data *cfqd = cic->key; |
| |
| if (cfqd) { |
| struct request_queue *q = cfqd->queue; |
| unsigned long flags; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| |
| /* |
| * Ensure we get a fresh copy of the ->key to prevent |
| * race between exiting task and queue |
| */ |
| smp_read_barrier_depends(); |
| if (cic->key) |
| __cfq_exit_single_io_context(cfqd, cic); |
| |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| } |
| |
| /* |
| * The process that ioc belongs to has exited, we need to clean up |
| * and put the internal structures we have that belongs to that process. |
| */ |
| static void cfq_exit_io_context(struct io_context *ioc) |
| { |
| call_for_each_cic(ioc, cfq_exit_single_io_context); |
| } |
| |
| static struct cfq_io_context * |
| cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
| { |
| struct cfq_io_context *cic; |
| |
| cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
| cfqd->queue->node); |
| if (cic) { |
| cic->last_end_request = jiffies; |
| INIT_LIST_HEAD(&cic->queue_list); |
| INIT_HLIST_NODE(&cic->cic_list); |
| cic->dtor = cfq_free_io_context; |
| cic->exit = cfq_exit_io_context; |
| elv_ioc_count_inc(cfq_ioc_count); |
| } |
| |
| return cic; |
| } |
| |
| static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
| { |
| struct task_struct *tsk = current; |
| int ioprio_class; |
| |
| if (!cfq_cfqq_prio_changed(cfqq)) |
| return; |
| |
| ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
| switch (ioprio_class) { |
| default: |
| printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); |
| case IOPRIO_CLASS_NONE: |
| /* |
| * no prio set, inherit CPU scheduling settings |
| */ |
| cfqq->ioprio = task_nice_ioprio(tsk); |
| cfqq->ioprio_class = task_nice_ioclass(tsk); |
| break; |
| case IOPRIO_CLASS_RT: |
| cfqq->ioprio = task_ioprio(ioc); |
| cfqq->ioprio_class = IOPRIO_CLASS_RT; |
| break; |
| case IOPRIO_CLASS_BE: |
| cfqq->ioprio = task_ioprio(ioc); |
| cfqq->ioprio_class = IOPRIO_CLASS_BE; |
| break; |
| case IOPRIO_CLASS_IDLE: |
| cfqq->ioprio_class = IOPRIO_CLASS_IDLE; |
| cfqq->ioprio = 7; |
| cfq_clear_cfqq_idle_window(cfqq); |
| break; |
| } |
| |
| /* |
| * keep track of original prio settings in case we have to temporarily |
| * elevate the priority of this queue |
| */ |
| cfqq->org_ioprio = cfqq->ioprio; |
| cfqq->org_ioprio_class = cfqq->ioprio_class; |
| cfq_clear_cfqq_prio_changed(cfqq); |
| } |
| |
| static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
| { |
| struct cfq_data *cfqd = cic->key; |
| struct cfq_queue *cfqq; |
| unsigned long flags; |
| |
| if (unlikely(!cfqd)) |
| return; |
| |
| spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| |
| cfqq = cic->cfqq[BLK_RW_ASYNC]; |
| if (cfqq) { |
| struct cfq_queue *new_cfqq; |
| new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
| GFP_ATOMIC); |
| if (new_cfqq) { |
| cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
| cfq_put_queue(cfqq); |
| } |
| } |
| |
| cfqq = cic->cfqq[BLK_RW_SYNC]; |
| if (cfqq) |
| cfq_mark_cfqq_prio_changed(cfqq); |
| |
| spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| } |
| |
| static void cfq_ioc_set_ioprio(struct io_context *ioc) |
| { |
| call_for_each_cic(ioc, changed_ioprio); |
| ioc->ioprio_changed = 0; |
| } |
| |
| static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| pid_t pid, int is_sync) |
| { |
| RB_CLEAR_NODE(&cfqq->rb_node); |
| RB_CLEAR_NODE(&cfqq->p_node); |
| INIT_LIST_HEAD(&cfqq->fifo); |
| |
| atomic_set(&cfqq->ref, 0); |
| cfqq->cfqd = cfqd; |
| |
| cfq_mark_cfqq_prio_changed(cfqq); |
| |
| if (is_sync) { |
| if (!cfq_class_idle(cfqq)) |
| cfq_mark_cfqq_idle_window(cfqq); |
| cfq_mark_cfqq_sync(cfqq); |
| } |
| cfqq->pid = pid; |
| } |
| |
| static struct cfq_queue * |
| cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync, |
| struct io_context *ioc, gfp_t gfp_mask) |
| { |
| struct cfq_queue *cfqq, *new_cfqq = NULL; |
| struct cfq_io_context *cic; |
| |
| retry: |
| cic = cfq_cic_lookup(cfqd, ioc); |
| /* cic always exists here */ |
| cfqq = cic_to_cfqq(cic, is_sync); |
| |
| /* |
| * Always try a new alloc if we fell back to the OOM cfqq |
| * originally, since it should just be a temporary situation. |
| */ |
| if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
| cfqq = NULL; |
| if (new_cfqq) { |
| cfqq = new_cfqq; |
| new_cfqq = NULL; |
| } else if (gfp_mask & __GFP_WAIT) { |
| spin_unlock_irq(cfqd->queue->queue_lock); |
| new_cfqq = kmem_cache_alloc_node(cfq_pool, |
| gfp_mask | __GFP_ZERO, |
| cfqd->queue->node); |
| spin_lock_irq(cfqd->queue->queue_lock); |
| if (new_cfqq) |
| goto retry; |
| } else { |
| cfqq = kmem_cache_alloc_node(cfq_pool, |
| gfp_mask | __GFP_ZERO, |
| cfqd->queue->node); |
| } |
| |
| if (cfqq) { |
| cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); |
| cfq_init_prio_data(cfqq, ioc); |
| cfq_log_cfqq(cfqd, cfqq, "alloced"); |
| } else |
| cfqq = &cfqd->oom_cfqq; |
| } |
| |
| if (new_cfqq) |
| kmem_cache_free(cfq_pool, new_cfqq); |
| |
| return cfqq; |
| } |
| |
| static struct cfq_queue ** |
| cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) |
| { |
| switch (ioprio_class) { |
| case IOPRIO_CLASS_RT: |
| return &cfqd->async_cfqq[0][ioprio]; |
| case IOPRIO_CLASS_BE: |
| return &cfqd->async_cfqq[1][ioprio]; |
| case IOPRIO_CLASS_IDLE: |
| return &cfqd->async_idle_cfqq; |
| default: |
| BUG(); |
| } |
| } |
| |
| static struct cfq_queue * |
| cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc, |
| gfp_t gfp_mask) |
| { |
| const int ioprio = task_ioprio(ioc); |
| const int ioprio_class = task_ioprio_class(ioc); |
| struct cfq_queue **async_cfqq = NULL; |
| struct cfq_queue *cfqq = NULL; |
| |
| if (!is_sync) { |
| async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); |
| cfqq = *async_cfqq; |
| } |
| |
| if (!cfqq) |
| cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
| |
| /* |
| * pin the queue now that it's allocated, scheduler exit will prune it |
| */ |
| if (!is_sync && !(*async_cfqq)) { |
| atomic_inc(&cfqq->ref); |
| *async_cfqq = cfqq; |
| } |
| |
| atomic_inc(&cfqq->ref); |
| return cfqq; |
| } |
| |
| /* |
| * We drop cfq io contexts lazily, so we may find a dead one. |
| */ |
| static void |
| cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
| struct cfq_io_context *cic) |
| { |
| unsigned long flags; |
| |
| WARN_ON(!list_empty(&cic->queue_list)); |
| |
| spin_lock_irqsave(&ioc->lock, flags); |
| |
| BUG_ON(ioc->ioc_data == cic); |
| |
| radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
| hlist_del_rcu(&cic->cic_list); |
| spin_unlock_irqrestore(&ioc->lock, flags); |
| |
| cfq_cic_free(cic); |
| } |
| |
| static struct cfq_io_context * |
| cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
| { |
| struct cfq_io_context *cic; |
| unsigned long flags; |
| void *k; |
| |
| if (unlikely(!ioc)) |
| return NULL; |
| |
| rcu_read_lock(); |
| |
| /* |
| * we maintain a last-hit cache, to avoid browsing over the tree |
| */ |
| cic = rcu_dereference(ioc->ioc_data); |
| if (cic && cic->key == cfqd) { |
| rcu_read_unlock(); |
| return cic; |
| } |
| |
| do { |
| cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
| rcu_read_unlock(); |
| if (!cic) |
| break; |
| /* ->key must be copied to avoid race with cfq_exit_queue() */ |
| k = cic->key; |
| if (unlikely(!k)) { |
| cfq_drop_dead_cic(cfqd, ioc, cic); |
| rcu_read_lock(); |
| continue; |
| } |
| |
| spin_lock_irqsave(&ioc->lock, flags); |
| rcu_assign_pointer(ioc->ioc_data, cic); |
| spin_unlock_irqrestore(&ioc->lock, flags); |
| break; |
| } while (1); |
| |
| return cic; |
| } |
| |
| /* |
| * Add cic into ioc, using cfqd as the search key. This enables us to lookup |
| * the process specific cfq io context when entered from the block layer. |
| * Also adds the cic to a per-cfqd list, used when this queue is removed. |
| */ |
| static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
| struct cfq_io_context *cic, gfp_t gfp_mask) |
| { |
| unsigned long flags; |
| int ret; |
| |
| ret = radix_tree_preload(gfp_mask); |
| if (!ret) { |
| cic->ioc = ioc; |
| cic->key = cfqd; |
| |
| spin_lock_irqsave(&ioc->lock, flags); |
| ret = radix_tree_insert(&ioc->radix_root, |
| (unsigned long) cfqd, cic); |
| if (!ret) |
| hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); |
| spin_unlock_irqrestore(&ioc->lock, flags); |
| |
| radix_tree_preload_end(); |
| |
| if (!ret) { |
| spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| list_add(&cic->queue_list, &cfqd->cic_list); |
| spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| } |
| } |
| |
| if (ret) |
| printk(KERN_ERR "cfq: cic link failed!\n"); |
| |
| return ret; |
| } |
| |
| /* |
| * Setup general io context and cfq io context. There can be several cfq |
| * io contexts per general io context, if this process is doing io to more |
| * than one device managed by cfq. |
| */ |
| static struct cfq_io_context * |
| cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
| { |
| struct io_context *ioc = NULL; |
| struct cfq_io_context *cic; |
| |
| might_sleep_if(gfp_mask & __GFP_WAIT); |
| |
| ioc = get_io_context(gfp_mask, cfqd->queue->node); |
| if (!ioc) |
| return NULL; |
| |
| cic = cfq_cic_lookup(cfqd, ioc); |
| if (cic) |
| goto out; |
| |
| cic = cfq_alloc_io_context(cfqd, gfp_mask); |
| if (cic == NULL) |
| goto err; |
| |
| if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
| goto err_free; |
| |
| out: |
| smp_read_barrier_depends(); |
| if (unlikely(ioc->ioprio_changed)) |
| cfq_ioc_set_ioprio(ioc); |
| |
| return cic; |
| err_free: |
| cfq_cic_free(cic); |
| err: |
| put_io_context(ioc); |
| return NULL; |
| } |
| |
| static void |
| cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) |
| { |
| unsigned long elapsed = jiffies - cic->last_end_request; |
| unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
| |
| cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
| cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; |
| cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; |
| } |
| |
| static void |
| cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, |
| struct request *rq) |
| { |
| sector_t sdist; |
| u64 total; |
| |
| if (!cic->last_request_pos) |
| sdist = 0; |
| else if (cic->last_request_pos < blk_rq_pos(rq)) |
| sdist = blk_rq_pos(rq) - cic->last_request_pos; |
| else |
| sdist = cic->last_request_pos - blk_rq_pos(rq); |
| |
| /* |
| * Don't allow the seek distance to get too large from the |
| * odd fragment, pagein, etc |
| */ |
| if (cic->seek_samples <= 60) /* second&third seek */ |
| sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); |
| else |
| sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); |
| |
| cic->seek_samples = (7*cic->seek_samples + 256) / 8; |
| cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; |
| total = cic->seek_total + (cic->seek_samples/2); |
| do_div(total, cic->seek_samples); |
| cic->seek_mean = (sector_t)total; |
| } |
| |
| /* |
| * Disable idle window if the process thinks too long or seeks so much that |
| * it doesn't matter |
| */ |
| static void |
| cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct cfq_io_context *cic) |
| { |
| int old_idle, enable_idle; |
| |
| /* |
| * Don't idle for async or idle io prio class |
| */ |
| if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) |
| return; |
| |
| enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
| |
| if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
| (!cfqd->cfq_latency && cfqd->hw_tag && CIC_SEEKY(cic))) |
| enable_idle = 0; |
| else if (sample_valid(cic->ttime_samples)) { |
| if (cic->ttime_mean > cfqd->cfq_slice_idle) |
| enable_idle = 0; |
| else |
| enable_idle = 1; |
| } |
| |
| if (old_idle != enable_idle) { |
| cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); |
| if (enable_idle) |
| cfq_mark_cfqq_idle_window(cfqq); |
| else |
| cfq_clear_cfqq_idle_window(cfqq); |
| } |
| } |
| |
| /* |
| * Check if new_cfqq should preempt the currently active queue. Return 0 for |
| * no or if we aren't sure, a 1 will cause a preempt. |
| */ |
| static int |
| cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
| struct request *rq) |
| { |
| struct cfq_queue *cfqq; |
| |
| cfqq = cfqd->active_queue; |
| if (!cfqq) |
| return 0; |
| |
| if (cfq_slice_used(cfqq)) |
| return 1; |
| |
| if (cfq_class_idle(new_cfqq)) |
| return 0; |
| |
| if (cfq_class_idle(cfqq)) |
| return 1; |
| |
| /* |
| * if the new request is sync, but the currently running queue is |
| * not, let the sync request have priority. |
| */ |
| if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
| return 1; |
| |
| /* |
| * So both queues are sync. Let the new request get disk time if |
| * it's a metadata request and the current queue is doing regular IO. |
| */ |
| if (rq_is_meta(rq) && !cfqq->meta_pending) |
| return 1; |
| |
| /* |
| * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. |
| */ |
| if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) |
| return 1; |
| |
| if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
| return 0; |
| |
| /* |
| * if this request is as-good as one we would expect from the |
| * current cfqq, let it preempt |
| */ |
| if (cfq_rq_close(cfqd, rq)) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* |
| * cfqq preempts the active queue. if we allowed preempt with no slice left, |
| * let it have half of its nominal slice. |
| */ |
| static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "preempt"); |
| cfq_slice_expired(cfqd, 1); |
| |
| /* |
| * Put the new queue at the front of the of the current list, |
| * so we know that it will be selected next. |
| */ |
| BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| |
| cfq_service_tree_add(cfqd, cfqq, 1); |
| |
| cfqq->slice_end = 0; |
| cfq_mark_cfqq_slice_new(cfqq); |
| } |
| |
| /* |
| * Called when a new fs request (rq) is added (to cfqq). Check if there's |
| * something we should do about it |
| */ |
| static void |
| cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *rq) |
| { |
| struct cfq_io_context *cic = RQ_CIC(rq); |
| |
| cfqd->rq_queued++; |
| if (rq_is_meta(rq)) |
| cfqq->meta_pending++; |
| |
| cfq_update_io_thinktime(cfqd, cic); |
| cfq_update_io_seektime(cfqd, cic, rq); |
| cfq_update_idle_window(cfqd, cfqq, cic); |
| |
| cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| |
| if (cfqq == cfqd->active_queue) { |
| /* |
| * Remember that we saw a request from this process, but |
| * don't start queuing just yet. Otherwise we risk seeing lots |
| * of tiny requests, because we disrupt the normal plugging |
| * and merging. If the request is already larger than a single |
| * page, let it rip immediately. For that case we assume that |
| * merging is already done. Ditto for a busy system that |
| * has other work pending, don't risk delaying until the |
| * idle timer unplug to continue working. |
| */ |
| if (cfq_cfqq_wait_request(cfqq)) { |
| if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
| cfqd->busy_queues > 1) { |
| del_timer(&cfqd->idle_slice_timer); |
| __blk_run_queue(cfqd->queue); |
| } |
| cfq_mark_cfqq_must_dispatch(cfqq); |
| } |
| } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
| /* |
| * not the active queue - expire current slice if it is |
| * idle and has expired it's mean thinktime or this new queue |
| * has some old slice time left and is of higher priority or |
| * this new queue is RT and the current one is BE |
| */ |
| cfq_preempt_queue(cfqd, cfqq); |
| __blk_run_queue(cfqd->queue); |
| } |
| } |
| |
| static void cfq_insert_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
| cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
| |
| cfq_add_rq_rb(rq); |
| |
| list_add_tail(&rq->queuelist, &cfqq->fifo); |
| |
| cfq_rq_enqueued(cfqd, cfqq, rq); |
| } |
| |
| /* |
| * Update hw_tag based on peak queue depth over 50 samples under |
| * sufficient load. |
| */ |
| static void cfq_update_hw_tag(struct cfq_data *cfqd) |
| { |
| if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak) |
| cfqd->rq_in_driver_peak = rq_in_driver(cfqd); |
| |
| if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && |
| rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
| return; |
| |
| if (cfqd->hw_tag_samples++ < 50) |
| return; |
| |
| if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN) |
| cfqd->hw_tag = 1; |
| else |
| cfqd->hw_tag = 0; |
| |
| cfqd->hw_tag_samples = 0; |
| cfqd->rq_in_driver_peak = 0; |
| } |
| |
| static void cfq_completed_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| struct cfq_data *cfqd = cfqq->cfqd; |
| const int sync = rq_is_sync(rq); |
| unsigned long now; |
| |
| now = jiffies; |
| cfq_log_cfqq(cfqd, cfqq, "complete"); |
| |
| cfq_update_hw_tag(cfqd); |
| |
| WARN_ON(!cfqd->rq_in_driver[sync]); |
| WARN_ON(!cfqq->dispatched); |
| cfqd->rq_in_driver[sync]--; |
| cfqq->dispatched--; |
| |
| if (cfq_cfqq_sync(cfqq)) |
| cfqd->sync_flight--; |
| |
| if (sync) { |
| RQ_CIC(rq)->last_end_request = now; |
| cfqd->last_end_sync_rq = now; |
| } |
| |
| /* |
| * If this is the active queue, check if it needs to be expired, |
| * or if we want to idle in case it has no pending requests. |
| */ |
| if (cfqd->active_queue == cfqq) { |
| const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
| |
| if (cfq_cfqq_slice_new(cfqq)) { |
| cfq_set_prio_slice(cfqd, cfqq); |
| cfq_clear_cfqq_slice_new(cfqq); |
| } |
| /* |
| * If there are no requests waiting in this queue, and |
| * there are other queues ready to issue requests, AND |
| * those other queues are issuing requests within our |
| * mean seek distance, give them a chance to run instead |
| * of idling. |
| */ |
| if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
| cfq_slice_expired(cfqd, 1); |
| else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) && |
| sync && !rq_noidle(rq)) |
| cfq_arm_slice_timer(cfqd); |
| } |
| |
| if (!rq_in_driver(cfqd)) |
| cfq_schedule_dispatch(cfqd, 0); |
| } |
| |
| /* |
| * we temporarily boost lower priority queues if they are holding fs exclusive |
| * resources. they are boosted to normal prio (CLASS_BE/4) |
| */ |
| static void cfq_prio_boost(struct cfq_queue *cfqq) |
| { |
| if (has_fs_excl()) { |
| /* |
| * boost idle prio on transactions that would lock out other |
| * users of the filesystem |
| */ |
| if (cfq_class_idle(cfqq)) |
| cfqq->ioprio_class = IOPRIO_CLASS_BE; |
| if (cfqq->ioprio > IOPRIO_NORM) |
| cfqq->ioprio = IOPRIO_NORM; |
| } else { |
| /* |
| * check if we need to unboost the queue |
| */ |
| if (cfqq->ioprio_class != cfqq->org_ioprio_class) |
| cfqq->ioprio_class = cfqq->org_ioprio_class; |
| if (cfqq->ioprio != cfqq->org_ioprio) |
| cfqq->ioprio = cfqq->org_ioprio; |
| } |
| } |
| |
| static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
| { |
| if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
| cfq_mark_cfqq_must_alloc_slice(cfqq); |
| return ELV_MQUEUE_MUST; |
| } |
| |
| return ELV_MQUEUE_MAY; |
| } |
| |
| static int cfq_may_queue(struct request_queue *q, int rw) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct task_struct *tsk = current; |
| struct cfq_io_context *cic; |
| struct cfq_queue *cfqq; |
| |
| /* |
| * don't force setup of a queue from here, as a call to may_queue |
| * does not necessarily imply that a request actually will be queued. |
| * so just lookup a possibly existing queue, or return 'may queue' |
| * if that fails |
| */ |
| cic = cfq_cic_lookup(cfqd, tsk->io_context); |
| if (!cic) |
| return ELV_MQUEUE_MAY; |
| |
| cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
| if (cfqq) { |
| cfq_init_prio_data(cfqq, cic->ioc); |
| cfq_prio_boost(cfqq); |
| |
| return __cfq_may_queue(cfqq); |
| } |
| |
| return ELV_MQUEUE_MAY; |
| } |
| |
| /* |
| * queue lock held here |
| */ |
| static void cfq_put_request(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| if (cfqq) { |
| const int rw = rq_data_dir(rq); |
| |
| BUG_ON(!cfqq->allocated[rw]); |
| cfqq->allocated[rw]--; |
| |
| put_io_context(RQ_CIC(rq)->ioc); |
| |
| rq->elevator_private = NULL; |
| rq->elevator_private2 = NULL; |
| |
| cfq_put_queue(cfqq); |
| } |
| } |
| |
| /* |
| * Allocate cfq data structures associated with this request. |
| */ |
| static int |
| cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_io_context *cic; |
| const int rw = rq_data_dir(rq); |
| const int is_sync = rq_is_sync(rq); |
| struct cfq_queue *cfqq; |
| unsigned long flags; |
| |
| might_sleep_if(gfp_mask & __GFP_WAIT); |
| |
| cic = cfq_get_io_context(cfqd, gfp_mask); |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| |
| if (!cic) |
| goto queue_fail; |
| |
| cfqq = cic_to_cfqq(cic, is_sync); |
| if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
| cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
| cic_set_cfqq(cic, cfqq, is_sync); |
| } |
| |
| cfqq->allocated[rw]++; |
| atomic_inc(&cfqq->ref); |
| |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| |
| rq->elevator_private = cic; |
| rq->elevator_private2 = cfqq; |
| return 0; |
| |
| queue_fail: |
| if (cic) |
| put_io_context(cic->ioc); |
| |
| cfq_schedule_dispatch(cfqd, 0); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| cfq_log(cfqd, "set_request fail"); |
| return 1; |
| } |
| |
| static void cfq_kick_queue(struct work_struct *work) |
| { |
| struct cfq_data *cfqd = |
| container_of(work, struct cfq_data, unplug_work.work); |
| struct request_queue *q = cfqd->queue; |
| |
| spin_lock_irq(q->queue_lock); |
| __blk_run_queue(cfqd->queue); |
| spin_unlock_irq(q->queue_lock); |
| } |
| |
| /* |
| * Timer running if the active_queue is currently idling inside its time slice |
| */ |
| static void cfq_idle_slice_timer(unsigned long data) |
| { |
| struct cfq_data *cfqd = (struct cfq_data *) data; |
| struct cfq_queue *cfqq; |
| unsigned long flags; |
| int timed_out = 1; |
| |
| cfq_log(cfqd, "idle timer fired"); |
| |
| spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| |
| cfqq = cfqd->active_queue; |
| if (cfqq) { |
| timed_out = 0; |
| |
| /* |
| * We saw a request before the queue expired, let it through |
| */ |
| if (cfq_cfqq_must_dispatch(cfqq)) |
| goto out_kick; |
| |
| /* |
| * expired |
| */ |
| if (cfq_slice_used(cfqq)) |
| goto expire; |
| |
| /* |
| * only expire and reinvoke request handler, if there are |
| * other queues with pending requests |
| */ |
| if (!cfqd->busy_queues) |
| goto out_cont; |
| |
| /* |
| * not expired and it has a request pending, let it dispatch |
| */ |
| if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
| goto out_kick; |
| } |
| expire: |
| cfq_slice_expired(cfqd, timed_out); |
| out_kick: |
| cfq_schedule_dispatch(cfqd, 0); |
| out_cont: |
| spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| } |
| |
| static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
| { |
| del_timer_sync(&cfqd->idle_slice_timer); |
| cancel_delayed_work_sync(&cfqd->unplug_work); |
| } |
| |
| static void cfq_put_async_queues(struct cfq_data *cfqd) |
| { |
| int i; |
| |
| for (i = 0; i < IOPRIO_BE_NR; i++) { |
| if (cfqd->async_cfqq[0][i]) |
| cfq_put_queue(cfqd->async_cfqq[0][i]); |
| if (cfqd->async_cfqq[1][i]) |
| cfq_put_queue(cfqd->async_cfqq[1][i]); |
| } |
| |
| if (cfqd->async_idle_cfqq) |
| cfq_put_queue(cfqd->async_idle_cfqq); |
| } |
| |
| static void cfq_exit_queue(struct elevator_queue *e) |
| { |
| struct cfq_data *cfqd = e->elevator_data; |
| struct request_queue *q = cfqd->queue; |
| |
| cfq_shutdown_timer_wq(cfqd); |
| |
| spin_lock_irq(q->queue_lock); |
| |
| if (cfqd->active_queue) |
| __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
| |
| while (!list_empty(&cfqd->cic_list)) { |
| struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
| struct cfq_io_context, |
| queue_list); |
| |
| __cfq_exit_single_io_context(cfqd, cic); |
| } |
| |
| cfq_put_async_queues(cfqd); |
| |
| spin_unlock_irq(q->queue_lock); |
| |
| cfq_shutdown_timer_wq(cfqd); |
| |
| kfree(cfqd); |
| } |
| |
| static void *cfq_init_queue(struct request_queue *q) |
| { |
| struct cfq_data *cfqd; |
| int i; |
| |
| cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
| if (!cfqd) |
| return NULL; |
| |
| cfqd->service_tree = CFQ_RB_ROOT; |
| |
| /* |
| * Not strictly needed (since RB_ROOT just clears the node and we |
| * zeroed cfqd on alloc), but better be safe in case someone decides |
| * to add magic to the rb code |
| */ |
| for (i = 0; i < CFQ_PRIO_LISTS; i++) |
| cfqd->prio_trees[i] = RB_ROOT; |
| |
| /* |
| * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. |
| * Grab a permanent reference to it, so that the normal code flow |
| * will not attempt to free it. |
| */ |
| cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); |
| atomic_inc(&cfqd->oom_cfqq.ref); |
| |
| INIT_LIST_HEAD(&cfqd->cic_list); |
| |
| cfqd->queue = q; |
| |
| init_timer(&cfqd->idle_slice_timer); |
| cfqd->idle_slice_timer.function = cfq_idle_slice_timer; |
| cfqd->idle_slice_timer.data = (unsigned long) cfqd; |
| |
| INIT_DELAYED_WORK(&cfqd->unplug_work, cfq_kick_queue); |
| |
| cfqd->cfq_quantum = cfq_quantum; |
| cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
| cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; |
| cfqd->cfq_back_max = cfq_back_max; |
| cfqd->cfq_back_penalty = cfq_back_penalty; |
| cfqd->cfq_slice[0] = cfq_slice_async; |
| cfqd->cfq_slice[1] = cfq_slice_sync; |
| cfqd->cfq_slice_async_rq = cfq_slice_async_rq; |
| cfqd->cfq_slice_idle = cfq_slice_idle; |
| cfqd->cfq_latency = 1; |
| cfqd->hw_tag = 1; |
| cfqd->last_end_sync_rq = jiffies; |
| return cfqd; |
| } |
| |
| static void cfq_slab_kill(void) |
| { |
| /* |
| * Caller already ensured that pending RCU callbacks are completed, |
| * so we should have no busy allocations at this point. |
| */ |
| if (cfq_pool) |
| kmem_cache_destroy(cfq_pool); |
| if (cfq_ioc_pool) |
| kmem_cache_destroy(cfq_ioc_pool); |
| } |
| |
| static int __init cfq_slab_setup(void) |
| { |
| cfq_pool = KMEM_CACHE(cfq_queue, 0); |
| if (!cfq_pool) |
| goto fail; |
| |
| cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
| if (!cfq_ioc_pool) |
| goto fail; |
| |
| return 0; |
| fail: |
| cfq_slab_kill(); |
| return -ENOMEM; |
| } |
| |
| /* |
| * sysfs parts below --> |
| */ |
| static ssize_t |
| cfq_var_show(unsigned int var, char *page) |
| { |
| return sprintf(page, "%d\n", var); |
| } |
| |
| static ssize_t |
| cfq_var_store(unsigned int *var, const char *page, size_t count) |
| { |
| char *p = (char *) page; |
| |
| *var = simple_strtoul(p, &p, 10); |
| return count; |
| } |
| |
| #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
| static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
| { \ |
| struct cfq_data *cfqd = e->elevator_data; \ |
| unsigned int __data = __VAR; \ |
| if (__CONV) \ |
| __data = jiffies_to_msecs(__data); \ |
| return cfq_var_show(__data, (page)); \ |
| } |
| SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); |
| SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
| SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); |
| SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
| SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); |
| SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
| SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); |
| SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); |
| SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); |
| SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
| #undef SHOW_FUNCTION |
| |
| #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ |
| static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
| { \ |
| struct cfq_data *cfqd = e->elevator_data; \ |
| unsigned int __data; \ |
| int ret = cfq_var_store(&__data, (page), count); \ |
| if (__data < (MIN)) \ |
| __data = (MIN); \ |
| else if (__data > (MAX)) \ |
| __data = (MAX); \ |
| if (__CONV) \ |
| *(__PTR) = msecs_to_jiffies(__data); \ |
| else \ |
| *(__PTR) = __data; \ |
| return ret; \ |
| } |
| STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); |
| STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
| UINT_MAX, 1); |
| STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, |
| UINT_MAX, 1); |
| STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
| STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
| UINT_MAX, 0); |
| STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
| STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); |
| STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); |
| STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
| UINT_MAX, 0); |
| STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
| #undef STORE_FUNCTION |
| |
| #define CFQ_ATTR(name) \ |
| __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) |
| |
| static struct elv_fs_entry cfq_attrs[] = { |
| CFQ_ATTR(quantum), |
| CFQ_ATTR(fifo_expire_sync), |
| CFQ_ATTR(fifo_expire_async), |
| CFQ_ATTR(back_seek_max), |
| CFQ_ATTR(back_seek_penalty), |
| CFQ_ATTR(slice_sync), |
| CFQ_ATTR(slice_async), |
| CFQ_ATTR(slice_async_rq), |
| CFQ_ATTR(slice_idle), |
| CFQ_ATTR(low_latency), |
| __ATTR_NULL |
| }; |
| |
| static struct elevator_type iosched_cfq = { |
| .ops = { |
| .elevator_merge_fn = cfq_merge, |
| .elevator_merged_fn = cfq_merged_request, |
| .elevator_merge_req_fn = cfq_merged_requests, |
| .elevator_allow_merge_fn = cfq_allow_merge, |
| .elevator_dispatch_fn = cfq_dispatch_requests, |
| .elevator_add_req_fn = cfq_insert_request, |
| .elevator_activate_req_fn = cfq_activate_request, |
| .elevator_deactivate_req_fn = cfq_deactivate_request, |
| .elevator_queue_empty_fn = cfq_queue_empty, |
| .elevator_completed_req_fn = cfq_completed_request, |
| .elevator_former_req_fn = elv_rb_former_request, |
| .elevator_latter_req_fn = elv_rb_latter_request, |
| .elevator_set_req_fn = cfq_set_request, |
| .elevator_put_req_fn = cfq_put_request, |
| .elevator_may_queue_fn = cfq_may_queue, |
| .elevator_init_fn = cfq_init_queue, |
| .elevator_exit_fn = cfq_exit_queue, |
| .trim = cfq_free_io_context, |
| }, |
| .elevator_attrs = cfq_attrs, |
| .elevator_name = "cfq", |
| .elevator_owner = THIS_MODULE, |
| }; |
| |
| static int __init cfq_init(void) |
| { |
| /* |
| * could be 0 on HZ < 1000 setups |
| */ |
| if (!cfq_slice_async) |
| cfq_slice_async = 1; |
| if (!cfq_slice_idle) |
| cfq_slice_idle = 1; |
| |
| if (cfq_slab_setup()) |
| return -ENOMEM; |
| |
| elv_register(&iosched_cfq); |
| |
| return 0; |
| } |
| |
| static void __exit cfq_exit(void) |
| { |
| DECLARE_COMPLETION_ONSTACK(all_gone); |
| elv_unregister(&iosched_cfq); |
| ioc_gone = &all_gone; |
| /* ioc_gone's update must be visible before reading ioc_count */ |
| smp_wmb(); |
| |
| /* |
| * this also protects us from entering cfq_slab_kill() with |
| * pending RCU callbacks |
| */ |
| if (elv_ioc_count_read(cfq_ioc_count)) |
| wait_for_completion(&all_gone); |
| cfq_slab_kill(); |
| } |
| |
| module_init(cfq_init); |
| module_exit(cfq_exit); |
| |
| MODULE_AUTHOR("Jens Axboe"); |
| MODULE_LICENSE("GPL"); |
| MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |