2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/blkdev.h>
11 #include <linux/elevator.h>
12 #include <linux/rbtree.h>
13 #include <linux/ioprio.h>
14 #include <linux/blktrace_api.h>
19 /* max queue in one round of service */
20 static const int cfq_quantum = 4;
21 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
22 /* maximum backwards seek, in KiB */
23 static const int cfq_back_max = 16 * 1024;
24 /* penalty of a backwards seek */
25 static const int cfq_back_penalty = 2;
26 static const int cfq_slice_sync = HZ / 10;
27 static int cfq_slice_async = HZ / 25;
28 static const int cfq_slice_async_rq = 2;
29 static int cfq_slice_idle = HZ / 125;
32 * offset from end of service tree
34 #define CFQ_IDLE_DELAY (HZ / 5)
37 * below this threshold, we consider thinktime immediate
39 #define CFQ_MIN_TT (2)
41 #define CFQ_SLICE_SCALE (5)
42 #define CFQ_HW_QUEUE_MIN (5)
45 ((struct cfq_io_context *) (rq)->elevator_private)
46 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
48 static struct kmem_cache *cfq_pool;
49 static struct kmem_cache *cfq_ioc_pool;
51 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
52 static struct completion *ioc_gone;
53 static DEFINE_SPINLOCK(ioc_gone_lock);
55 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
56 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
57 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
59 #define sample_valid(samples) ((samples) > 80)
62 * Most of our rbtree usage is for sorting with min extraction, so
63 * if we cache the leftmost node we don't have to walk down the tree
64 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
65 * move this into the elevator for the rq sorting as well.
71 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
74 * Per process-grouping structure
79 /* various state flags, see below */
82 struct cfq_data *cfqd;
83 /* service_tree member */
84 struct rb_node rb_node;
85 /* service_tree key */
87 /* prio tree member */
88 struct rb_node p_node;
89 /* prio tree root we belong to, if any */
90 struct rb_root *p_root;
91 /* sorted list of pending requests */
92 struct rb_root sort_list;
93 /* if fifo isn't expired, next request to serve */
94 struct request *next_rq;
95 /* requests queued in sort_list */
97 /* currently allocated requests */
99 /* fifo list of requests in sort_list */
100 struct list_head fifo;
102 unsigned long slice_end;
104 unsigned int slice_dispatch;
106 /* pending metadata requests */
108 /* number of requests that are on the dispatch list or inside driver */
111 /* io prio of this group */
112 unsigned short ioprio, org_ioprio;
113 unsigned short ioprio_class, org_ioprio_class;
119 * Per block device queue structure
122 struct request_queue *queue;
125 * rr list of queues with requests and the count of them
127 struct cfq_rb_root service_tree;
130 * Each priority tree is sorted by next_request position. These
131 * trees are used when determining if two or more queues are
132 * interleaving requests (see cfq_close_cooperator).
134 struct rb_root prio_trees[CFQ_PRIO_LISTS];
136 unsigned int busy_queues;
142 * queue-depth detection
147 int rq_in_driver_peak;
150 * idle window management
152 struct timer_list idle_slice_timer;
153 struct work_struct unplug_work;
155 struct cfq_queue *active_queue;
156 struct cfq_io_context *active_cic;
159 * async queue for each priority case
161 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
162 struct cfq_queue *async_idle_cfqq;
164 sector_t last_position;
167 * tunables, see top of file
169 unsigned int cfq_quantum;
170 unsigned int cfq_fifo_expire[2];
171 unsigned int cfq_back_penalty;
172 unsigned int cfq_back_max;
173 unsigned int cfq_slice[2];
174 unsigned int cfq_slice_async_rq;
175 unsigned int cfq_slice_idle;
177 struct list_head cic_list;
180 * Fallback dummy cfqq for extreme OOM conditions
182 struct cfq_queue oom_cfqq;
185 enum cfqq_state_flags {
186 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
187 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
188 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
189 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
190 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
191 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
192 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
193 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
194 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
195 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
198 #define CFQ_CFQQ_FNS(name) \
199 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
201 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
203 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
205 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
207 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
209 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
213 CFQ_CFQQ_FNS(wait_request);
214 CFQ_CFQQ_FNS(must_dispatch);
215 CFQ_CFQQ_FNS(must_alloc_slice);
216 CFQ_CFQQ_FNS(fifo_expire);
217 CFQ_CFQQ_FNS(idle_window);
218 CFQ_CFQQ_FNS(prio_changed);
219 CFQ_CFQQ_FNS(slice_new);
224 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
225 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
226 #define cfq_log(cfqd, fmt, args...) \
227 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
229 static void cfq_dispatch_insert(struct request_queue *, struct request *);
230 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
231 struct io_context *, gfp_t);
232 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
233 struct io_context *);
235 static inline int rq_in_driver(struct cfq_data *cfqd)
237 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
240 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
243 return cic->cfqq[!!is_sync];
246 static inline void cic_set_cfqq(struct cfq_io_context *cic,
247 struct cfq_queue *cfqq, int is_sync)
249 cic->cfqq[!!is_sync] = cfqq;
253 * We regard a request as SYNC, if it's either a read or has the SYNC bit
254 * set (in which case it could also be direct WRITE).
256 static inline int cfq_bio_sync(struct bio *bio)
258 if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO))
265 * scheduler run of queue, if there are requests pending and no one in the
266 * driver that will restart queueing
268 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
270 if (cfqd->busy_queues) {
271 cfq_log(cfqd, "schedule dispatch");
272 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
276 static int cfq_queue_empty(struct request_queue *q)
278 struct cfq_data *cfqd = q->elevator->elevator_data;
280 return !cfqd->busy_queues;
284 * Scale schedule slice based on io priority. Use the sync time slice only
285 * if a queue is marked sync and has sync io queued. A sync queue with async
286 * io only, should not get full sync slice length.
288 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
291 const int base_slice = cfqd->cfq_slice[sync];
293 WARN_ON(prio >= IOPRIO_BE_NR);
295 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
299 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
301 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
305 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
307 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
308 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
312 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
313 * isn't valid until the first request from the dispatch is activated
314 * and the slice time set.
316 static inline int cfq_slice_used(struct cfq_queue *cfqq)
318 if (cfq_cfqq_slice_new(cfqq))
320 if (time_before(jiffies, cfqq->slice_end))
327 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
328 * We choose the request that is closest to the head right now. Distance
329 * behind the head is penalized and only allowed to a certain extent.
331 static struct request *
332 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
334 sector_t last, s1, s2, d1 = 0, d2 = 0;
335 unsigned long back_max;
336 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
337 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
338 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
340 if (rq1 == NULL || rq1 == rq2)
345 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
347 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
349 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
351 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
354 s1 = blk_rq_pos(rq1);
355 s2 = blk_rq_pos(rq2);
357 last = cfqd->last_position;
360 * by definition, 1KiB is 2 sectors
362 back_max = cfqd->cfq_back_max * 2;
365 * Strict one way elevator _except_ in the case where we allow
366 * short backward seeks which are biased as twice the cost of a
367 * similar forward seek.
371 else if (s1 + back_max >= last)
372 d1 = (last - s1) * cfqd->cfq_back_penalty;
374 wrap |= CFQ_RQ1_WRAP;
378 else if (s2 + back_max >= last)
379 d2 = (last - s2) * cfqd->cfq_back_penalty;
381 wrap |= CFQ_RQ2_WRAP;
383 /* Found required data */
386 * By doing switch() on the bit mask "wrap" we avoid having to
387 * check two variables for all permutations: --> faster!
390 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
406 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
409 * Since both rqs are wrapped,
410 * start with the one that's further behind head
411 * (--> only *one* back seek required),
412 * since back seek takes more time than forward.
422 * The below is leftmost cache rbtree addon
424 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
427 root->left = rb_first(&root->rb);
430 return rb_entry(root->left, struct cfq_queue, rb_node);
435 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
441 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
445 rb_erase_init(n, &root->rb);
449 * would be nice to take fifo expire time into account as well
451 static struct request *
452 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
453 struct request *last)
455 struct rb_node *rbnext = rb_next(&last->rb_node);
456 struct rb_node *rbprev = rb_prev(&last->rb_node);
457 struct request *next = NULL, *prev = NULL;
459 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
462 prev = rb_entry_rq(rbprev);
465 next = rb_entry_rq(rbnext);
467 rbnext = rb_first(&cfqq->sort_list);
468 if (rbnext && rbnext != &last->rb_node)
469 next = rb_entry_rq(rbnext);
472 return cfq_choose_req(cfqd, next, prev);
475 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
476 struct cfq_queue *cfqq)
479 * just an approximation, should be ok.
481 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
482 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
486 * The cfqd->service_tree holds all pending cfq_queue's that have
487 * requests waiting to be processed. It is sorted in the order that
488 * we will service the queues.
490 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
493 struct rb_node **p, *parent;
494 struct cfq_queue *__cfqq;
495 unsigned long rb_key;
498 if (cfq_class_idle(cfqq)) {
499 rb_key = CFQ_IDLE_DELAY;
500 parent = rb_last(&cfqd->service_tree.rb);
501 if (parent && parent != &cfqq->rb_node) {
502 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
503 rb_key += __cfqq->rb_key;
506 } else if (!add_front) {
507 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
508 rb_key += cfqq->slice_resid;
509 cfqq->slice_resid = 0;
513 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
515 * same position, nothing more to do
517 if (rb_key == cfqq->rb_key)
520 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
525 p = &cfqd->service_tree.rb.rb_node;
530 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
533 * sort RT queues first, we always want to give
534 * preference to them. IDLE queues goes to the back.
535 * after that, sort on the next service time.
537 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
539 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
541 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
543 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
545 else if (rb_key < __cfqq->rb_key)
550 if (n == &(*p)->rb_right)
557 cfqd->service_tree.left = &cfqq->rb_node;
559 cfqq->rb_key = rb_key;
560 rb_link_node(&cfqq->rb_node, parent, p);
561 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
564 static struct cfq_queue *
565 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
566 sector_t sector, struct rb_node **ret_parent,
567 struct rb_node ***rb_link)
569 struct rb_node **p, *parent;
570 struct cfq_queue *cfqq = NULL;
578 cfqq = rb_entry(parent, struct cfq_queue, p_node);
581 * Sort strictly based on sector. Smallest to the left,
582 * largest to the right.
584 if (sector > blk_rq_pos(cfqq->next_rq))
586 else if (sector < blk_rq_pos(cfqq->next_rq))
594 *ret_parent = parent;
600 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
602 struct rb_node **p, *parent;
603 struct cfq_queue *__cfqq;
606 rb_erase(&cfqq->p_node, cfqq->p_root);
610 if (cfq_class_idle(cfqq))
615 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
616 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
617 blk_rq_pos(cfqq->next_rq), &parent, &p);
619 rb_link_node(&cfqq->p_node, parent, p);
620 rb_insert_color(&cfqq->p_node, cfqq->p_root);
626 * Update cfqq's position in the service tree.
628 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
631 * Resorting requires the cfqq to be on the RR list already.
633 if (cfq_cfqq_on_rr(cfqq)) {
634 cfq_service_tree_add(cfqd, cfqq, 0);
635 cfq_prio_tree_add(cfqd, cfqq);
640 * add to busy list of queues for service, trying to be fair in ordering
641 * the pending list according to last request service
643 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
645 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
646 BUG_ON(cfq_cfqq_on_rr(cfqq));
647 cfq_mark_cfqq_on_rr(cfqq);
650 cfq_resort_rr_list(cfqd, cfqq);
654 * Called when the cfqq no longer has requests pending, remove it from
657 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
659 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
660 BUG_ON(!cfq_cfqq_on_rr(cfqq));
661 cfq_clear_cfqq_on_rr(cfqq);
663 if (!RB_EMPTY_NODE(&cfqq->rb_node))
664 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
666 rb_erase(&cfqq->p_node, cfqq->p_root);
670 BUG_ON(!cfqd->busy_queues);
675 * rb tree support functions
677 static void cfq_del_rq_rb(struct request *rq)
679 struct cfq_queue *cfqq = RQ_CFQQ(rq);
680 struct cfq_data *cfqd = cfqq->cfqd;
681 const int sync = rq_is_sync(rq);
683 BUG_ON(!cfqq->queued[sync]);
684 cfqq->queued[sync]--;
686 elv_rb_del(&cfqq->sort_list, rq);
688 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
689 cfq_del_cfqq_rr(cfqd, cfqq);
692 static void cfq_add_rq_rb(struct request *rq)
694 struct cfq_queue *cfqq = RQ_CFQQ(rq);
695 struct cfq_data *cfqd = cfqq->cfqd;
696 struct request *__alias, *prev;
698 cfqq->queued[rq_is_sync(rq)]++;
701 * looks a little odd, but the first insert might return an alias.
702 * if that happens, put the alias on the dispatch list
704 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
705 cfq_dispatch_insert(cfqd->queue, __alias);
707 if (!cfq_cfqq_on_rr(cfqq))
708 cfq_add_cfqq_rr(cfqd, cfqq);
711 * check if this request is a better next-serve candidate
713 prev = cfqq->next_rq;
714 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
717 * adjust priority tree position, if ->next_rq changes
719 if (prev != cfqq->next_rq)
720 cfq_prio_tree_add(cfqd, cfqq);
722 BUG_ON(!cfqq->next_rq);
725 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
727 elv_rb_del(&cfqq->sort_list, rq);
728 cfqq->queued[rq_is_sync(rq)]--;
732 static struct request *
733 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
735 struct task_struct *tsk = current;
736 struct cfq_io_context *cic;
737 struct cfq_queue *cfqq;
739 cic = cfq_cic_lookup(cfqd, tsk->io_context);
743 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
745 sector_t sector = bio->bi_sector + bio_sectors(bio);
747 return elv_rb_find(&cfqq->sort_list, sector);
753 static void cfq_activate_request(struct request_queue *q, struct request *rq)
755 struct cfq_data *cfqd = q->elevator->elevator_data;
757 cfqd->rq_in_driver[rq_is_sync(rq)]++;
758 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
761 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
764 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
766 struct cfq_data *cfqd = q->elevator->elevator_data;
767 const int sync = rq_is_sync(rq);
769 WARN_ON(!cfqd->rq_in_driver[sync]);
770 cfqd->rq_in_driver[sync]--;
771 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
775 static void cfq_remove_request(struct request *rq)
777 struct cfq_queue *cfqq = RQ_CFQQ(rq);
779 if (cfqq->next_rq == rq)
780 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
782 list_del_init(&rq->queuelist);
785 cfqq->cfqd->rq_queued--;
786 if (rq_is_meta(rq)) {
787 WARN_ON(!cfqq->meta_pending);
788 cfqq->meta_pending--;
792 static int cfq_merge(struct request_queue *q, struct request **req,
795 struct cfq_data *cfqd = q->elevator->elevator_data;
796 struct request *__rq;
798 __rq = cfq_find_rq_fmerge(cfqd, bio);
799 if (__rq && elv_rq_merge_ok(__rq, bio)) {
801 return ELEVATOR_FRONT_MERGE;
804 return ELEVATOR_NO_MERGE;
807 static void cfq_merged_request(struct request_queue *q, struct request *req,
810 if (type == ELEVATOR_FRONT_MERGE) {
811 struct cfq_queue *cfqq = RQ_CFQQ(req);
813 cfq_reposition_rq_rb(cfqq, req);
818 cfq_merged_requests(struct request_queue *q, struct request *rq,
819 struct request *next)
822 * reposition in fifo if next is older than rq
824 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
825 time_before(next->start_time, rq->start_time))
826 list_move(&rq->queuelist, &next->queuelist);
828 cfq_remove_request(next);
831 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
834 struct cfq_data *cfqd = q->elevator->elevator_data;
835 struct cfq_io_context *cic;
836 struct cfq_queue *cfqq;
839 * Disallow merge of a sync bio into an async request.
841 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
845 * Lookup the cfqq that this bio will be queued with. Allow
846 * merge only if rq is queued there.
848 cic = cfq_cic_lookup(cfqd, current->io_context);
852 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
853 if (cfqq == RQ_CFQQ(rq))
859 static void __cfq_set_active_queue(struct cfq_data *cfqd,
860 struct cfq_queue *cfqq)
863 cfq_log_cfqq(cfqd, cfqq, "set_active");
865 cfqq->slice_dispatch = 0;
867 cfq_clear_cfqq_wait_request(cfqq);
868 cfq_clear_cfqq_must_dispatch(cfqq);
869 cfq_clear_cfqq_must_alloc_slice(cfqq);
870 cfq_clear_cfqq_fifo_expire(cfqq);
871 cfq_mark_cfqq_slice_new(cfqq);
873 del_timer(&cfqd->idle_slice_timer);
876 cfqd->active_queue = cfqq;
880 * current cfqq expired its slice (or was too idle), select new one
883 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
886 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
888 if (cfq_cfqq_wait_request(cfqq))
889 del_timer(&cfqd->idle_slice_timer);
891 cfq_clear_cfqq_wait_request(cfqq);
894 * store what was left of this slice, if the queue idled/timed out
896 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
897 cfqq->slice_resid = cfqq->slice_end - jiffies;
898 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
901 cfq_resort_rr_list(cfqd, cfqq);
903 if (cfqq == cfqd->active_queue)
904 cfqd->active_queue = NULL;
906 if (cfqd->active_cic) {
907 put_io_context(cfqd->active_cic->ioc);
908 cfqd->active_cic = NULL;
912 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
914 struct cfq_queue *cfqq = cfqd->active_queue;
917 __cfq_slice_expired(cfqd, cfqq, timed_out);
921 * Get next queue for service. Unless we have a queue preemption,
922 * we'll simply select the first cfqq in the service tree.
924 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
926 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
929 return cfq_rb_first(&cfqd->service_tree);
933 * Get and set a new active queue for service.
935 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
936 struct cfq_queue *cfqq)
939 cfqq = cfq_get_next_queue(cfqd);
941 cfq_clear_cfqq_coop(cfqq);
944 __cfq_set_active_queue(cfqd, cfqq);
948 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
951 if (blk_rq_pos(rq) >= cfqd->last_position)
952 return blk_rq_pos(rq) - cfqd->last_position;
954 return cfqd->last_position - blk_rq_pos(rq);
957 #define CIC_SEEK_THR 8 * 1024
958 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
960 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
962 struct cfq_io_context *cic = cfqd->active_cic;
963 sector_t sdist = cic->seek_mean;
965 if (!sample_valid(cic->seek_samples))
966 sdist = CIC_SEEK_THR;
968 return cfq_dist_from_last(cfqd, rq) <= sdist;
971 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
972 struct cfq_queue *cur_cfqq)
974 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
975 struct rb_node *parent, *node;
976 struct cfq_queue *__cfqq;
977 sector_t sector = cfqd->last_position;
979 if (RB_EMPTY_ROOT(root))
983 * First, if we find a request starting at the end of the last
984 * request, choose it.
986 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
991 * If the exact sector wasn't found, the parent of the NULL leaf
992 * will contain the closest sector.
994 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
995 if (cfq_rq_close(cfqd, __cfqq->next_rq))
998 if (blk_rq_pos(__cfqq->next_rq) < sector)
999 node = rb_next(&__cfqq->p_node);
1001 node = rb_prev(&__cfqq->p_node);
1005 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1006 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1014 * cur_cfqq - passed in so that we don't decide that the current queue is
1015 * closely cooperating with itself.
1017 * So, basically we're assuming that that cur_cfqq has dispatched at least
1018 * one request, and that cfqd->last_position reflects a position on the disk
1019 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1022 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1023 struct cfq_queue *cur_cfqq,
1026 struct cfq_queue *cfqq;
1029 * A valid cfq_io_context is necessary to compare requests against
1030 * the seek_mean of the current cfqq.
1032 if (!cfqd->active_cic)
1036 * We should notice if some of the queues are cooperating, eg
1037 * working closely on the same area of the disk. In that case,
1038 * we can group them together and don't waste time idling.
1040 cfqq = cfqq_close(cfqd, cur_cfqq);
1044 if (cfq_cfqq_coop(cfqq))
1048 cfq_mark_cfqq_coop(cfqq);
1052 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1054 struct cfq_queue *cfqq = cfqd->active_queue;
1055 struct cfq_io_context *cic;
1059 * SSD device without seek penalty, disable idling. But only do so
1060 * for devices that support queuing, otherwise we still have a problem
1061 * with sync vs async workloads.
1063 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1066 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1067 WARN_ON(cfq_cfqq_slice_new(cfqq));
1070 * idle is disabled, either manually or by past process history
1072 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1076 * still requests with the driver, don't idle
1078 if (rq_in_driver(cfqd))
1082 * task has exited, don't wait
1084 cic = cfqd->active_cic;
1085 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1088 cfq_mark_cfqq_wait_request(cfqq);
1091 * we don't want to idle for seeks, but we do want to allow
1092 * fair distribution of slice time for a process doing back-to-back
1093 * seeks. so allow a little bit of time for him to submit a new rq
1095 sl = cfqd->cfq_slice_idle;
1096 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1097 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1099 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1100 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1104 * Move request from internal lists to the request queue dispatch list.
1106 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1108 struct cfq_data *cfqd = q->elevator->elevator_data;
1109 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1111 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1113 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1114 cfq_remove_request(rq);
1116 elv_dispatch_sort(q, rq);
1118 if (cfq_cfqq_sync(cfqq))
1119 cfqd->sync_flight++;
1123 * return expired entry, or NULL to just start from scratch in rbtree
1125 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1127 struct cfq_data *cfqd = cfqq->cfqd;
1131 if (cfq_cfqq_fifo_expire(cfqq))
1134 cfq_mark_cfqq_fifo_expire(cfqq);
1136 if (list_empty(&cfqq->fifo))
1139 fifo = cfq_cfqq_sync(cfqq);
1140 rq = rq_entry_fifo(cfqq->fifo.next);
1142 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
1145 cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
1150 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1152 const int base_rq = cfqd->cfq_slice_async_rq;
1154 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1156 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1160 * Select a queue for service. If we have a current active queue,
1161 * check whether to continue servicing it, or retrieve and set a new one.
1163 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1165 struct cfq_queue *cfqq, *new_cfqq = NULL;
1167 cfqq = cfqd->active_queue;
1172 * The active queue has run out of time, expire it and select new.
1174 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1178 * The active queue has requests and isn't expired, allow it to
1181 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1185 * If another queue has a request waiting within our mean seek
1186 * distance, let it run. The expire code will check for close
1187 * cooperators and put the close queue at the front of the service
1190 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1195 * No requests pending. If the active queue still has requests in
1196 * flight or is idling for a new request, allow either of these
1197 * conditions to happen (or time out) before selecting a new queue.
1199 if (timer_pending(&cfqd->idle_slice_timer) ||
1200 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1206 cfq_slice_expired(cfqd, 0);
1208 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1213 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1217 while (cfqq->next_rq) {
1218 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1222 BUG_ON(!list_empty(&cfqq->fifo));
1227 * Drain our current requests. Used for barriers and when switching
1228 * io schedulers on-the-fly.
1230 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1232 struct cfq_queue *cfqq;
1235 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1236 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1238 cfq_slice_expired(cfqd, 0);
1240 BUG_ON(cfqd->busy_queues);
1242 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1247 * Dispatch a request from cfqq, moving them to the request queue
1250 static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1254 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1257 * follow expired path, else get first next available
1259 rq = cfq_check_fifo(cfqq);
1264 * insert request into driver dispatch list
1266 cfq_dispatch_insert(cfqd->queue, rq);
1268 if (!cfqd->active_cic) {
1269 struct cfq_io_context *cic = RQ_CIC(rq);
1271 atomic_long_inc(&cic->ioc->refcount);
1272 cfqd->active_cic = cic;
1277 * Find the cfqq that we need to service and move a request from that to the
1280 static int cfq_dispatch_requests(struct request_queue *q, int force)
1282 struct cfq_data *cfqd = q->elevator->elevator_data;
1283 struct cfq_queue *cfqq;
1284 unsigned int max_dispatch;
1286 if (!cfqd->busy_queues)
1289 if (unlikely(force))
1290 return cfq_forced_dispatch(cfqd);
1292 cfqq = cfq_select_queue(cfqd);
1297 * Drain async requests before we start sync IO
1299 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1303 * If this is an async queue and we have sync IO in flight, let it wait
1305 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1308 max_dispatch = cfqd->cfq_quantum;
1309 if (cfq_class_idle(cfqq))
1313 * Does this cfqq already have too much IO in flight?
1315 if (cfqq->dispatched >= max_dispatch) {
1317 * idle queue must always only have a single IO in flight
1319 if (cfq_class_idle(cfqq))
1323 * We have other queues, don't allow more IO from this one
1325 if (cfqd->busy_queues > 1)
1329 * we are the only queue, allow up to 4 times of 'quantum'
1331 if (cfqq->dispatched >= 4 * max_dispatch)
1336 * Dispatch a request from this cfqq
1338 cfq_dispatch_request(cfqd, cfqq);
1339 cfqq->slice_dispatch++;
1340 cfq_clear_cfqq_must_dispatch(cfqq);
1343 * expire an async queue immediately if it has used up its slice. idle
1344 * queue always expire after 1 dispatch round.
1346 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1347 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1348 cfq_class_idle(cfqq))) {
1349 cfqq->slice_end = jiffies + 1;
1350 cfq_slice_expired(cfqd, 0);
1353 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
1358 * task holds one reference to the queue, dropped when task exits. each rq
1359 * in-flight on this queue also holds a reference, dropped when rq is freed.
1361 * queue lock must be held here.
1363 static void cfq_put_queue(struct cfq_queue *cfqq)
1365 struct cfq_data *cfqd = cfqq->cfqd;
1367 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1369 if (!atomic_dec_and_test(&cfqq->ref))
1372 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1373 BUG_ON(rb_first(&cfqq->sort_list));
1374 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1375 BUG_ON(cfq_cfqq_on_rr(cfqq));
1377 if (unlikely(cfqd->active_queue == cfqq)) {
1378 __cfq_slice_expired(cfqd, cfqq, 0);
1379 cfq_schedule_dispatch(cfqd);
1382 kmem_cache_free(cfq_pool, cfqq);
1386 * Must always be called with the rcu_read_lock() held
1389 __call_for_each_cic(struct io_context *ioc,
1390 void (*func)(struct io_context *, struct cfq_io_context *))
1392 struct cfq_io_context *cic;
1393 struct hlist_node *n;
1395 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1400 * Call func for each cic attached to this ioc.
1403 call_for_each_cic(struct io_context *ioc,
1404 void (*func)(struct io_context *, struct cfq_io_context *))
1407 __call_for_each_cic(ioc, func);
1411 static void cfq_cic_free_rcu(struct rcu_head *head)
1413 struct cfq_io_context *cic;
1415 cic = container_of(head, struct cfq_io_context, rcu_head);
1417 kmem_cache_free(cfq_ioc_pool, cic);
1418 elv_ioc_count_dec(cfq_ioc_count);
1422 * CFQ scheduler is exiting, grab exit lock and check
1423 * the pending io context count. If it hits zero,
1424 * complete ioc_gone and set it back to NULL
1426 spin_lock(&ioc_gone_lock);
1427 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
1431 spin_unlock(&ioc_gone_lock);
1435 static void cfq_cic_free(struct cfq_io_context *cic)
1437 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1440 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1442 unsigned long flags;
1444 BUG_ON(!cic->dead_key);
1446 spin_lock_irqsave(&ioc->lock, flags);
1447 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1448 hlist_del_rcu(&cic->cic_list);
1449 spin_unlock_irqrestore(&ioc->lock, flags);
1455 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1456 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1457 * and ->trim() which is called with the task lock held
1459 static void cfq_free_io_context(struct io_context *ioc)
1462 * ioc->refcount is zero here, or we are called from elv_unregister(),
1463 * so no more cic's are allowed to be linked into this ioc. So it
1464 * should be ok to iterate over the known list, we will see all cic's
1465 * since no new ones are added.
1467 __call_for_each_cic(ioc, cic_free_func);
1470 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1472 if (unlikely(cfqq == cfqd->active_queue)) {
1473 __cfq_slice_expired(cfqd, cfqq, 0);
1474 cfq_schedule_dispatch(cfqd);
1477 cfq_put_queue(cfqq);
1480 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1481 struct cfq_io_context *cic)
1483 struct io_context *ioc = cic->ioc;
1485 list_del_init(&cic->queue_list);
1488 * Make sure key == NULL is seen for dead queues
1491 cic->dead_key = (unsigned long) cic->key;
1494 if (ioc->ioc_data == cic)
1495 rcu_assign_pointer(ioc->ioc_data, NULL);
1497 if (cic->cfqq[BLK_RW_ASYNC]) {
1498 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1499 cic->cfqq[BLK_RW_ASYNC] = NULL;
1502 if (cic->cfqq[BLK_RW_SYNC]) {
1503 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1504 cic->cfqq[BLK_RW_SYNC] = NULL;
1508 static void cfq_exit_single_io_context(struct io_context *ioc,
1509 struct cfq_io_context *cic)
1511 struct cfq_data *cfqd = cic->key;
1514 struct request_queue *q = cfqd->queue;
1515 unsigned long flags;
1517 spin_lock_irqsave(q->queue_lock, flags);
1520 * Ensure we get a fresh copy of the ->key to prevent
1521 * race between exiting task and queue
1523 smp_read_barrier_depends();
1525 __cfq_exit_single_io_context(cfqd, cic);
1527 spin_unlock_irqrestore(q->queue_lock, flags);
1532 * The process that ioc belongs to has exited, we need to clean up
1533 * and put the internal structures we have that belongs to that process.
1535 static void cfq_exit_io_context(struct io_context *ioc)
1537 call_for_each_cic(ioc, cfq_exit_single_io_context);
1540 static struct cfq_io_context *
1541 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1543 struct cfq_io_context *cic;
1545 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1548 cic->last_end_request = jiffies;
1549 INIT_LIST_HEAD(&cic->queue_list);
1550 INIT_HLIST_NODE(&cic->cic_list);
1551 cic->dtor = cfq_free_io_context;
1552 cic->exit = cfq_exit_io_context;
1553 elv_ioc_count_inc(cfq_ioc_count);
1559 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1561 struct task_struct *tsk = current;
1564 if (!cfq_cfqq_prio_changed(cfqq))
1567 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1568 switch (ioprio_class) {
1570 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1571 case IOPRIO_CLASS_NONE:
1573 * no prio set, inherit CPU scheduling settings
1575 cfqq->ioprio = task_nice_ioprio(tsk);
1576 cfqq->ioprio_class = task_nice_ioclass(tsk);
1578 case IOPRIO_CLASS_RT:
1579 cfqq->ioprio = task_ioprio(ioc);
1580 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1582 case IOPRIO_CLASS_BE:
1583 cfqq->ioprio = task_ioprio(ioc);
1584 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1586 case IOPRIO_CLASS_IDLE:
1587 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1589 cfq_clear_cfqq_idle_window(cfqq);
1594 * keep track of original prio settings in case we have to temporarily
1595 * elevate the priority of this queue
1597 cfqq->org_ioprio = cfqq->ioprio;
1598 cfqq->org_ioprio_class = cfqq->ioprio_class;
1599 cfq_clear_cfqq_prio_changed(cfqq);
1602 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1604 struct cfq_data *cfqd = cic->key;
1605 struct cfq_queue *cfqq;
1606 unsigned long flags;
1608 if (unlikely(!cfqd))
1611 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1613 cfqq = cic->cfqq[BLK_RW_ASYNC];
1615 struct cfq_queue *new_cfqq;
1616 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1619 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1620 cfq_put_queue(cfqq);
1624 cfqq = cic->cfqq[BLK_RW_SYNC];
1626 cfq_mark_cfqq_prio_changed(cfqq);
1628 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1631 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1633 call_for_each_cic(ioc, changed_ioprio);
1634 ioc->ioprio_changed = 0;
1637 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1638 pid_t pid, int is_sync)
1640 RB_CLEAR_NODE(&cfqq->rb_node);
1641 RB_CLEAR_NODE(&cfqq->p_node);
1642 INIT_LIST_HEAD(&cfqq->fifo);
1644 atomic_set(&cfqq->ref, 0);
1647 cfq_mark_cfqq_prio_changed(cfqq);
1650 if (!cfq_class_idle(cfqq))
1651 cfq_mark_cfqq_idle_window(cfqq);
1652 cfq_mark_cfqq_sync(cfqq);
1657 static struct cfq_queue *
1658 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1659 struct io_context *ioc, gfp_t gfp_mask)
1661 struct cfq_queue *cfqq, *new_cfqq = NULL;
1662 struct cfq_io_context *cic;
1665 cic = cfq_cic_lookup(cfqd, ioc);
1666 /* cic always exists here */
1667 cfqq = cic_to_cfqq(cic, is_sync);
1670 * Always try a new alloc if we fell back to the OOM cfqq
1671 * originally, since it should just be a temporary situation.
1673 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1678 } else if (gfp_mask & __GFP_WAIT) {
1679 spin_unlock_irq(cfqd->queue->queue_lock);
1680 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1681 gfp_mask | __GFP_ZERO,
1683 spin_lock_irq(cfqd->queue->queue_lock);
1687 cfqq = kmem_cache_alloc_node(cfq_pool,
1688 gfp_mask | __GFP_ZERO,
1693 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1694 cfq_init_prio_data(cfqq, ioc);
1695 cfq_log_cfqq(cfqd, cfqq, "alloced");
1697 cfqq = &cfqd->oom_cfqq;
1701 kmem_cache_free(cfq_pool, new_cfqq);
1706 static struct cfq_queue **
1707 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1709 switch (ioprio_class) {
1710 case IOPRIO_CLASS_RT:
1711 return &cfqd->async_cfqq[0][ioprio];
1712 case IOPRIO_CLASS_BE:
1713 return &cfqd->async_cfqq[1][ioprio];
1714 case IOPRIO_CLASS_IDLE:
1715 return &cfqd->async_idle_cfqq;
1721 static struct cfq_queue *
1722 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1725 const int ioprio = task_ioprio(ioc);
1726 const int ioprio_class = task_ioprio_class(ioc);
1727 struct cfq_queue **async_cfqq = NULL;
1728 struct cfq_queue *cfqq = NULL;
1731 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1736 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1739 * pin the queue now that it's allocated, scheduler exit will prune it
1741 if (!is_sync && !(*async_cfqq)) {
1742 atomic_inc(&cfqq->ref);
1746 atomic_inc(&cfqq->ref);
1751 * We drop cfq io contexts lazily, so we may find a dead one.
1754 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1755 struct cfq_io_context *cic)
1757 unsigned long flags;
1759 WARN_ON(!list_empty(&cic->queue_list));
1761 spin_lock_irqsave(&ioc->lock, flags);
1763 BUG_ON(ioc->ioc_data == cic);
1765 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1766 hlist_del_rcu(&cic->cic_list);
1767 spin_unlock_irqrestore(&ioc->lock, flags);
1772 static struct cfq_io_context *
1773 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1775 struct cfq_io_context *cic;
1776 unsigned long flags;
1785 * we maintain a last-hit cache, to avoid browsing over the tree
1787 cic = rcu_dereference(ioc->ioc_data);
1788 if (cic && cic->key == cfqd) {
1794 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1798 /* ->key must be copied to avoid race with cfq_exit_queue() */
1801 cfq_drop_dead_cic(cfqd, ioc, cic);
1806 spin_lock_irqsave(&ioc->lock, flags);
1807 rcu_assign_pointer(ioc->ioc_data, cic);
1808 spin_unlock_irqrestore(&ioc->lock, flags);
1816 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1817 * the process specific cfq io context when entered from the block layer.
1818 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1820 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1821 struct cfq_io_context *cic, gfp_t gfp_mask)
1823 unsigned long flags;
1826 ret = radix_tree_preload(gfp_mask);
1831 spin_lock_irqsave(&ioc->lock, flags);
1832 ret = radix_tree_insert(&ioc->radix_root,
1833 (unsigned long) cfqd, cic);
1835 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1836 spin_unlock_irqrestore(&ioc->lock, flags);
1838 radix_tree_preload_end();
1841 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1842 list_add(&cic->queue_list, &cfqd->cic_list);
1843 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1848 printk(KERN_ERR "cfq: cic link failed!\n");
1854 * Setup general io context and cfq io context. There can be several cfq
1855 * io contexts per general io context, if this process is doing io to more
1856 * than one device managed by cfq.
1858 static struct cfq_io_context *
1859 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1861 struct io_context *ioc = NULL;
1862 struct cfq_io_context *cic;
1864 might_sleep_if(gfp_mask & __GFP_WAIT);
1866 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1870 cic = cfq_cic_lookup(cfqd, ioc);
1874 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1878 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1882 smp_read_barrier_depends();
1883 if (unlikely(ioc->ioprio_changed))
1884 cfq_ioc_set_ioprio(ioc);
1890 put_io_context(ioc);
1895 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1897 unsigned long elapsed = jiffies - cic->last_end_request;
1898 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1900 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1901 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1902 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1906 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1912 if (!cic->last_request_pos)
1914 else if (cic->last_request_pos < blk_rq_pos(rq))
1915 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1917 sdist = cic->last_request_pos - blk_rq_pos(rq);
1920 * Don't allow the seek distance to get too large from the
1921 * odd fragment, pagein, etc
1923 if (cic->seek_samples <= 60) /* second&third seek */
1924 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1926 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1928 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1929 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1930 total = cic->seek_total + (cic->seek_samples/2);
1931 do_div(total, cic->seek_samples);
1932 cic->seek_mean = (sector_t)total;
1936 * Disable idle window if the process thinks too long or seeks so much that
1940 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1941 struct cfq_io_context *cic)
1943 int old_idle, enable_idle;
1946 * Don't idle for async or idle io prio class
1948 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1951 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1953 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1954 (cfqd->hw_tag && CIC_SEEKY(cic)))
1956 else if (sample_valid(cic->ttime_samples)) {
1957 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1963 if (old_idle != enable_idle) {
1964 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
1966 cfq_mark_cfqq_idle_window(cfqq);
1968 cfq_clear_cfqq_idle_window(cfqq);
1973 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1974 * no or if we aren't sure, a 1 will cause a preempt.
1977 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1980 struct cfq_queue *cfqq;
1982 cfqq = cfqd->active_queue;
1986 if (cfq_slice_used(cfqq))
1989 if (cfq_class_idle(new_cfqq))
1992 if (cfq_class_idle(cfqq))
1996 * if the new request is sync, but the currently running queue is
1997 * not, let the sync request have priority.
1999 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2003 * So both queues are sync. Let the new request get disk time if
2004 * it's a metadata request and the current queue is doing regular IO.
2006 if (rq_is_meta(rq) && !cfqq->meta_pending)
2010 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2012 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2015 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2019 * if this request is as-good as one we would expect from the
2020 * current cfqq, let it preempt
2022 if (cfq_rq_close(cfqd, rq))
2029 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2030 * let it have half of its nominal slice.
2032 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2034 cfq_log_cfqq(cfqd, cfqq, "preempt");
2035 cfq_slice_expired(cfqd, 1);
2038 * Put the new queue at the front of the of the current list,
2039 * so we know that it will be selected next.
2041 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2043 cfq_service_tree_add(cfqd, cfqq, 1);
2045 cfqq->slice_end = 0;
2046 cfq_mark_cfqq_slice_new(cfqq);
2050 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2051 * something we should do about it
2054 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2057 struct cfq_io_context *cic = RQ_CIC(rq);
2061 cfqq->meta_pending++;
2063 cfq_update_io_thinktime(cfqd, cic);
2064 cfq_update_io_seektime(cfqd, cic, rq);
2065 cfq_update_idle_window(cfqd, cfqq, cic);
2067 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2069 if (cfqq == cfqd->active_queue) {
2071 * Remember that we saw a request from this process, but
2072 * don't start queuing just yet. Otherwise we risk seeing lots
2073 * of tiny requests, because we disrupt the normal plugging
2074 * and merging. If the request is already larger than a single
2075 * page, let it rip immediately. For that case we assume that
2076 * merging is already done. Ditto for a busy system that
2077 * has other work pending, don't risk delaying until the
2078 * idle timer unplug to continue working.
2080 if (cfq_cfqq_wait_request(cfqq)) {
2081 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2082 cfqd->busy_queues > 1) {
2083 del_timer(&cfqd->idle_slice_timer);
2084 __blk_run_queue(cfqd->queue);
2086 cfq_mark_cfqq_must_dispatch(cfqq);
2088 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2090 * not the active queue - expire current slice if it is
2091 * idle and has expired it's mean thinktime or this new queue
2092 * has some old slice time left and is of higher priority or
2093 * this new queue is RT and the current one is BE
2095 cfq_preempt_queue(cfqd, cfqq);
2096 __blk_run_queue(cfqd->queue);
2100 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2102 struct cfq_data *cfqd = q->elevator->elevator_data;
2103 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2105 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2106 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2110 list_add_tail(&rq->queuelist, &cfqq->fifo);
2112 cfq_rq_enqueued(cfqd, cfqq, rq);
2116 * Update hw_tag based on peak queue depth over 50 samples under
2119 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2121 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2122 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
2124 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2125 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2128 if (cfqd->hw_tag_samples++ < 50)
2131 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2136 cfqd->hw_tag_samples = 0;
2137 cfqd->rq_in_driver_peak = 0;
2140 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2142 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2143 struct cfq_data *cfqd = cfqq->cfqd;
2144 const int sync = rq_is_sync(rq);
2148 cfq_log_cfqq(cfqd, cfqq, "complete");
2150 cfq_update_hw_tag(cfqd);
2152 WARN_ON(!cfqd->rq_in_driver[sync]);
2153 WARN_ON(!cfqq->dispatched);
2154 cfqd->rq_in_driver[sync]--;
2157 if (cfq_cfqq_sync(cfqq))
2158 cfqd->sync_flight--;
2161 RQ_CIC(rq)->last_end_request = now;
2164 * If this is the active queue, check if it needs to be expired,
2165 * or if we want to idle in case it has no pending requests.
2167 if (cfqd->active_queue == cfqq) {
2168 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2170 if (cfq_cfqq_slice_new(cfqq)) {
2171 cfq_set_prio_slice(cfqd, cfqq);
2172 cfq_clear_cfqq_slice_new(cfqq);
2175 * If there are no requests waiting in this queue, and
2176 * there are other queues ready to issue requests, AND
2177 * those other queues are issuing requests within our
2178 * mean seek distance, give them a chance to run instead
2181 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2182 cfq_slice_expired(cfqd, 1);
2183 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2184 sync && !rq_noidle(rq))
2185 cfq_arm_slice_timer(cfqd);
2188 if (!rq_in_driver(cfqd))
2189 cfq_schedule_dispatch(cfqd);
2193 * we temporarily boost lower priority queues if they are holding fs exclusive
2194 * resources. they are boosted to normal prio (CLASS_BE/4)
2196 static void cfq_prio_boost(struct cfq_queue *cfqq)
2198 if (has_fs_excl()) {
2200 * boost idle prio on transactions that would lock out other
2201 * users of the filesystem
2203 if (cfq_class_idle(cfqq))
2204 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2205 if (cfqq->ioprio > IOPRIO_NORM)
2206 cfqq->ioprio = IOPRIO_NORM;
2209 * check if we need to unboost the queue
2211 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2212 cfqq->ioprio_class = cfqq->org_ioprio_class;
2213 if (cfqq->ioprio != cfqq->org_ioprio)
2214 cfqq->ioprio = cfqq->org_ioprio;
2218 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2220 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
2221 cfq_mark_cfqq_must_alloc_slice(cfqq);
2222 return ELV_MQUEUE_MUST;
2225 return ELV_MQUEUE_MAY;
2228 static int cfq_may_queue(struct request_queue *q, int rw)
2230 struct cfq_data *cfqd = q->elevator->elevator_data;
2231 struct task_struct *tsk = current;
2232 struct cfq_io_context *cic;
2233 struct cfq_queue *cfqq;
2236 * don't force setup of a queue from here, as a call to may_queue
2237 * does not necessarily imply that a request actually will be queued.
2238 * so just lookup a possibly existing queue, or return 'may queue'
2241 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2243 return ELV_MQUEUE_MAY;
2245 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2247 cfq_init_prio_data(cfqq, cic->ioc);
2248 cfq_prio_boost(cfqq);
2250 return __cfq_may_queue(cfqq);
2253 return ELV_MQUEUE_MAY;
2257 * queue lock held here
2259 static void cfq_put_request(struct request *rq)
2261 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2264 const int rw = rq_data_dir(rq);
2266 BUG_ON(!cfqq->allocated[rw]);
2267 cfqq->allocated[rw]--;
2269 put_io_context(RQ_CIC(rq)->ioc);
2271 rq->elevator_private = NULL;
2272 rq->elevator_private2 = NULL;
2274 cfq_put_queue(cfqq);
2279 * Allocate cfq data structures associated with this request.
2282 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2284 struct cfq_data *cfqd = q->elevator->elevator_data;
2285 struct cfq_io_context *cic;
2286 const int rw = rq_data_dir(rq);
2287 const int is_sync = rq_is_sync(rq);
2288 struct cfq_queue *cfqq;
2289 unsigned long flags;
2291 might_sleep_if(gfp_mask & __GFP_WAIT);
2293 cic = cfq_get_io_context(cfqd, gfp_mask);
2295 spin_lock_irqsave(q->queue_lock, flags);
2300 cfqq = cic_to_cfqq(cic, is_sync);
2301 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2302 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2303 cic_set_cfqq(cic, cfqq, is_sync);
2306 cfqq->allocated[rw]++;
2307 atomic_inc(&cfqq->ref);
2309 spin_unlock_irqrestore(q->queue_lock, flags);
2311 rq->elevator_private = cic;
2312 rq->elevator_private2 = cfqq;
2317 put_io_context(cic->ioc);
2319 cfq_schedule_dispatch(cfqd);
2320 spin_unlock_irqrestore(q->queue_lock, flags);
2321 cfq_log(cfqd, "set_request fail");
2325 static void cfq_kick_queue(struct work_struct *work)
2327 struct cfq_data *cfqd =
2328 container_of(work, struct cfq_data, unplug_work);
2329 struct request_queue *q = cfqd->queue;
2331 spin_lock_irq(q->queue_lock);
2332 __blk_run_queue(cfqd->queue);
2333 spin_unlock_irq(q->queue_lock);
2337 * Timer running if the active_queue is currently idling inside its time slice
2339 static void cfq_idle_slice_timer(unsigned long data)
2341 struct cfq_data *cfqd = (struct cfq_data *) data;
2342 struct cfq_queue *cfqq;
2343 unsigned long flags;
2346 cfq_log(cfqd, "idle timer fired");
2348 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2350 cfqq = cfqd->active_queue;
2355 * We saw a request before the queue expired, let it through
2357 if (cfq_cfqq_must_dispatch(cfqq))
2363 if (cfq_slice_used(cfqq))
2367 * only expire and reinvoke request handler, if there are
2368 * other queues with pending requests
2370 if (!cfqd->busy_queues)
2374 * not expired and it has a request pending, let it dispatch
2376 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2380 cfq_slice_expired(cfqd, timed_out);
2382 cfq_schedule_dispatch(cfqd);
2384 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2387 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2389 del_timer_sync(&cfqd->idle_slice_timer);
2390 cancel_work_sync(&cfqd->unplug_work);
2393 static void cfq_put_async_queues(struct cfq_data *cfqd)
2397 for (i = 0; i < IOPRIO_BE_NR; i++) {
2398 if (cfqd->async_cfqq[0][i])
2399 cfq_put_queue(cfqd->async_cfqq[0][i]);
2400 if (cfqd->async_cfqq[1][i])
2401 cfq_put_queue(cfqd->async_cfqq[1][i]);
2404 if (cfqd->async_idle_cfqq)
2405 cfq_put_queue(cfqd->async_idle_cfqq);
2408 static void cfq_exit_queue(struct elevator_queue *e)
2410 struct cfq_data *cfqd = e->elevator_data;
2411 struct request_queue *q = cfqd->queue;
2413 cfq_shutdown_timer_wq(cfqd);
2415 spin_lock_irq(q->queue_lock);
2417 if (cfqd->active_queue)
2418 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2420 while (!list_empty(&cfqd->cic_list)) {
2421 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2422 struct cfq_io_context,
2425 __cfq_exit_single_io_context(cfqd, cic);
2428 cfq_put_async_queues(cfqd);
2430 spin_unlock_irq(q->queue_lock);
2432 cfq_shutdown_timer_wq(cfqd);
2437 static void *cfq_init_queue(struct request_queue *q)
2439 struct cfq_data *cfqd;
2442 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2446 cfqd->service_tree = CFQ_RB_ROOT;
2449 * Not strictly needed (since RB_ROOT just clears the node and we
2450 * zeroed cfqd on alloc), but better be safe in case someone decides
2451 * to add magic to the rb code
2453 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2454 cfqd->prio_trees[i] = RB_ROOT;
2457 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2458 * Grab a permanent reference to it, so that the normal code flow
2459 * will not attempt to free it.
2461 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2462 atomic_inc(&cfqd->oom_cfqq.ref);
2464 INIT_LIST_HEAD(&cfqd->cic_list);
2468 init_timer(&cfqd->idle_slice_timer);
2469 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2470 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2472 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
2474 cfqd->cfq_quantum = cfq_quantum;
2475 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2476 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2477 cfqd->cfq_back_max = cfq_back_max;
2478 cfqd->cfq_back_penalty = cfq_back_penalty;
2479 cfqd->cfq_slice[0] = cfq_slice_async;
2480 cfqd->cfq_slice[1] = cfq_slice_sync;
2481 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2482 cfqd->cfq_slice_idle = cfq_slice_idle;
2488 static void cfq_slab_kill(void)
2491 * Caller already ensured that pending RCU callbacks are completed,
2492 * so we should have no busy allocations at this point.
2495 kmem_cache_destroy(cfq_pool);
2497 kmem_cache_destroy(cfq_ioc_pool);
2500 static int __init cfq_slab_setup(void)
2502 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2506 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2517 * sysfs parts below -->
2520 cfq_var_show(unsigned int var, char *page)
2522 return sprintf(page, "%d\n", var);
2526 cfq_var_store(unsigned int *var, const char *page, size_t count)
2528 char *p = (char *) page;
2530 *var = simple_strtoul(p, &p, 10);
2534 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2535 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2537 struct cfq_data *cfqd = e->elevator_data; \
2538 unsigned int __data = __VAR; \
2540 __data = jiffies_to_msecs(__data); \
2541 return cfq_var_show(__data, (page)); \
2543 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2544 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2545 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2546 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2547 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2548 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2549 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2550 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2551 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2552 #undef SHOW_FUNCTION
2554 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2555 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2557 struct cfq_data *cfqd = e->elevator_data; \
2558 unsigned int __data; \
2559 int ret = cfq_var_store(&__data, (page), count); \
2560 if (__data < (MIN)) \
2562 else if (__data > (MAX)) \
2565 *(__PTR) = msecs_to_jiffies(__data); \
2567 *(__PTR) = __data; \
2570 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2571 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2573 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2575 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2576 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2578 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2579 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2580 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2581 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2583 #undef STORE_FUNCTION
2585 #define CFQ_ATTR(name) \
2586 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2588 static struct elv_fs_entry cfq_attrs[] = {
2590 CFQ_ATTR(fifo_expire_sync),
2591 CFQ_ATTR(fifo_expire_async),
2592 CFQ_ATTR(back_seek_max),
2593 CFQ_ATTR(back_seek_penalty),
2594 CFQ_ATTR(slice_sync),
2595 CFQ_ATTR(slice_async),
2596 CFQ_ATTR(slice_async_rq),
2597 CFQ_ATTR(slice_idle),
2601 static struct elevator_type iosched_cfq = {
2603 .elevator_merge_fn = cfq_merge,
2604 .elevator_merged_fn = cfq_merged_request,
2605 .elevator_merge_req_fn = cfq_merged_requests,
2606 .elevator_allow_merge_fn = cfq_allow_merge,
2607 .elevator_dispatch_fn = cfq_dispatch_requests,
2608 .elevator_add_req_fn = cfq_insert_request,
2609 .elevator_activate_req_fn = cfq_activate_request,
2610 .elevator_deactivate_req_fn = cfq_deactivate_request,
2611 .elevator_queue_empty_fn = cfq_queue_empty,
2612 .elevator_completed_req_fn = cfq_completed_request,
2613 .elevator_former_req_fn = elv_rb_former_request,
2614 .elevator_latter_req_fn = elv_rb_latter_request,
2615 .elevator_set_req_fn = cfq_set_request,
2616 .elevator_put_req_fn = cfq_put_request,
2617 .elevator_may_queue_fn = cfq_may_queue,
2618 .elevator_init_fn = cfq_init_queue,
2619 .elevator_exit_fn = cfq_exit_queue,
2620 .trim = cfq_free_io_context,
2622 .elevator_attrs = cfq_attrs,
2623 .elevator_name = "cfq",
2624 .elevator_owner = THIS_MODULE,
2627 static int __init cfq_init(void)
2630 * could be 0 on HZ < 1000 setups
2632 if (!cfq_slice_async)
2633 cfq_slice_async = 1;
2634 if (!cfq_slice_idle)
2637 if (cfq_slab_setup())
2640 elv_register(&iosched_cfq);
2645 static void __exit cfq_exit(void)
2647 DECLARE_COMPLETION_ONSTACK(all_gone);
2648 elv_unregister(&iosched_cfq);
2649 ioc_gone = &all_gone;
2650 /* ioc_gone's update must be visible before reading ioc_count */
2654 * this also protects us from entering cfq_slab_kill() with
2655 * pending RCU callbacks
2657 if (elv_ioc_count_read(cfq_ioc_count))
2658 wait_for_completion(&all_gone);
2662 module_init(cfq_init);
2663 module_exit(cfq_exit);
2665 MODULE_AUTHOR("Jens Axboe");
2666 MODULE_LICENSE("GPL");
2667 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");