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 delayed_work 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;
176 unsigned int cfq_latency;
178 struct list_head cic_list;
181 * Fallback dummy cfqq for extreme OOM conditions
183 struct cfq_queue oom_cfqq;
185 unsigned long last_end_sync_rq;
188 enum cfqq_state_flags {
189 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
190 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
191 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
192 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
193 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
194 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
195 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
196 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
197 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
198 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
201 #define CFQ_CFQQ_FNS(name) \
202 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
204 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
206 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
208 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
210 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
212 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
216 CFQ_CFQQ_FNS(wait_request);
217 CFQ_CFQQ_FNS(must_dispatch);
218 CFQ_CFQQ_FNS(must_alloc_slice);
219 CFQ_CFQQ_FNS(fifo_expire);
220 CFQ_CFQQ_FNS(idle_window);
221 CFQ_CFQQ_FNS(prio_changed);
222 CFQ_CFQQ_FNS(slice_new);
227 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
228 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
229 #define cfq_log(cfqd, fmt, args...) \
230 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
232 static void cfq_dispatch_insert(struct request_queue *, struct request *);
233 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
234 struct io_context *, gfp_t);
235 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
236 struct io_context *);
238 static inline int rq_in_driver(struct cfq_data *cfqd)
240 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
243 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
246 return cic->cfqq[!!is_sync];
249 static inline void cic_set_cfqq(struct cfq_io_context *cic,
250 struct cfq_queue *cfqq, int is_sync)
252 cic->cfqq[!!is_sync] = cfqq;
256 * We regard a request as SYNC, if it's either a read or has the SYNC bit
257 * set (in which case it could also be direct WRITE).
259 static inline int cfq_bio_sync(struct bio *bio)
261 if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO))
268 * scheduler run of queue, if there are requests pending and no one in the
269 * driver that will restart queueing
271 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd,
274 if (cfqd->busy_queues) {
275 cfq_log(cfqd, "schedule dispatch");
276 kblockd_schedule_delayed_work(cfqd->queue, &cfqd->unplug_work,
281 static int cfq_queue_empty(struct request_queue *q)
283 struct cfq_data *cfqd = q->elevator->elevator_data;
285 return !cfqd->busy_queues;
289 * Scale schedule slice based on io priority. Use the sync time slice only
290 * if a queue is marked sync and has sync io queued. A sync queue with async
291 * io only, should not get full sync slice length.
293 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
296 const int base_slice = cfqd->cfq_slice[sync];
298 WARN_ON(prio >= IOPRIO_BE_NR);
300 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
304 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
306 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
310 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
312 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
313 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
317 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
318 * isn't valid until the first request from the dispatch is activated
319 * and the slice time set.
321 static inline int cfq_slice_used(struct cfq_queue *cfqq)
323 if (cfq_cfqq_slice_new(cfqq))
325 if (time_before(jiffies, cfqq->slice_end))
332 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
333 * We choose the request that is closest to the head right now. Distance
334 * behind the head is penalized and only allowed to a certain extent.
336 static struct request *
337 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
339 sector_t last, s1, s2, d1 = 0, d2 = 0;
340 unsigned long back_max;
341 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
342 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
343 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
345 if (rq1 == NULL || rq1 == rq2)
350 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
352 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
354 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
356 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
359 s1 = blk_rq_pos(rq1);
360 s2 = blk_rq_pos(rq2);
362 last = cfqd->last_position;
365 * by definition, 1KiB is 2 sectors
367 back_max = cfqd->cfq_back_max * 2;
370 * Strict one way elevator _except_ in the case where we allow
371 * short backward seeks which are biased as twice the cost of a
372 * similar forward seek.
376 else if (s1 + back_max >= last)
377 d1 = (last - s1) * cfqd->cfq_back_penalty;
379 wrap |= CFQ_RQ1_WRAP;
383 else if (s2 + back_max >= last)
384 d2 = (last - s2) * cfqd->cfq_back_penalty;
386 wrap |= CFQ_RQ2_WRAP;
388 /* Found required data */
391 * By doing switch() on the bit mask "wrap" we avoid having to
392 * check two variables for all permutations: --> faster!
395 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
411 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
414 * Since both rqs are wrapped,
415 * start with the one that's further behind head
416 * (--> only *one* back seek required),
417 * since back seek takes more time than forward.
427 * The below is leftmost cache rbtree addon
429 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
432 root->left = rb_first(&root->rb);
435 return rb_entry(root->left, struct cfq_queue, rb_node);
440 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
446 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
450 rb_erase_init(n, &root->rb);
454 * would be nice to take fifo expire time into account as well
456 static struct request *
457 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
458 struct request *last)
460 struct rb_node *rbnext = rb_next(&last->rb_node);
461 struct rb_node *rbprev = rb_prev(&last->rb_node);
462 struct request *next = NULL, *prev = NULL;
464 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
467 prev = rb_entry_rq(rbprev);
470 next = rb_entry_rq(rbnext);
472 rbnext = rb_first(&cfqq->sort_list);
473 if (rbnext && rbnext != &last->rb_node)
474 next = rb_entry_rq(rbnext);
477 return cfq_choose_req(cfqd, next, prev);
480 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
481 struct cfq_queue *cfqq)
484 * just an approximation, should be ok.
486 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
487 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
491 * The cfqd->service_tree holds all pending cfq_queue's that have
492 * requests waiting to be processed. It is sorted in the order that
493 * we will service the queues.
495 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
498 struct rb_node **p, *parent;
499 struct cfq_queue *__cfqq;
500 unsigned long rb_key;
503 if (cfq_class_idle(cfqq)) {
504 rb_key = CFQ_IDLE_DELAY;
505 parent = rb_last(&cfqd->service_tree.rb);
506 if (parent && parent != &cfqq->rb_node) {
507 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
508 rb_key += __cfqq->rb_key;
511 } else if (!add_front) {
512 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
513 rb_key += cfqq->slice_resid;
514 cfqq->slice_resid = 0;
518 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
520 * same position, nothing more to do
522 if (rb_key == cfqq->rb_key)
525 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
530 p = &cfqd->service_tree.rb.rb_node;
535 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
538 * sort RT queues first, we always want to give
539 * preference to them. IDLE queues goes to the back.
540 * after that, sort on the next service time.
542 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
544 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
546 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
548 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
550 else if (rb_key < __cfqq->rb_key)
555 if (n == &(*p)->rb_right)
562 cfqd->service_tree.left = &cfqq->rb_node;
564 cfqq->rb_key = rb_key;
565 rb_link_node(&cfqq->rb_node, parent, p);
566 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
569 static struct cfq_queue *
570 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
571 sector_t sector, struct rb_node **ret_parent,
572 struct rb_node ***rb_link)
574 struct rb_node **p, *parent;
575 struct cfq_queue *cfqq = NULL;
583 cfqq = rb_entry(parent, struct cfq_queue, p_node);
586 * Sort strictly based on sector. Smallest to the left,
587 * largest to the right.
589 if (sector > blk_rq_pos(cfqq->next_rq))
591 else if (sector < blk_rq_pos(cfqq->next_rq))
599 *ret_parent = parent;
605 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
607 struct rb_node **p, *parent;
608 struct cfq_queue *__cfqq;
611 rb_erase(&cfqq->p_node, cfqq->p_root);
615 if (cfq_class_idle(cfqq))
620 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
621 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
622 blk_rq_pos(cfqq->next_rq), &parent, &p);
624 rb_link_node(&cfqq->p_node, parent, p);
625 rb_insert_color(&cfqq->p_node, cfqq->p_root);
631 * Update cfqq's position in the service tree.
633 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
636 * Resorting requires the cfqq to be on the RR list already.
638 if (cfq_cfqq_on_rr(cfqq)) {
639 cfq_service_tree_add(cfqd, cfqq, 0);
640 cfq_prio_tree_add(cfqd, cfqq);
645 * add to busy list of queues for service, trying to be fair in ordering
646 * the pending list according to last request service
648 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
650 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
651 BUG_ON(cfq_cfqq_on_rr(cfqq));
652 cfq_mark_cfqq_on_rr(cfqq);
655 cfq_resort_rr_list(cfqd, cfqq);
659 * Called when the cfqq no longer has requests pending, remove it from
662 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
664 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
665 BUG_ON(!cfq_cfqq_on_rr(cfqq));
666 cfq_clear_cfqq_on_rr(cfqq);
668 if (!RB_EMPTY_NODE(&cfqq->rb_node))
669 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
671 rb_erase(&cfqq->p_node, cfqq->p_root);
675 BUG_ON(!cfqd->busy_queues);
680 * rb tree support functions
682 static void cfq_del_rq_rb(struct request *rq)
684 struct cfq_queue *cfqq = RQ_CFQQ(rq);
685 struct cfq_data *cfqd = cfqq->cfqd;
686 const int sync = rq_is_sync(rq);
688 BUG_ON(!cfqq->queued[sync]);
689 cfqq->queued[sync]--;
691 elv_rb_del(&cfqq->sort_list, rq);
693 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
694 cfq_del_cfqq_rr(cfqd, cfqq);
697 static void cfq_add_rq_rb(struct request *rq)
699 struct cfq_queue *cfqq = RQ_CFQQ(rq);
700 struct cfq_data *cfqd = cfqq->cfqd;
701 struct request *__alias, *prev;
703 cfqq->queued[rq_is_sync(rq)]++;
706 * looks a little odd, but the first insert might return an alias.
707 * if that happens, put the alias on the dispatch list
709 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
710 cfq_dispatch_insert(cfqd->queue, __alias);
712 if (!cfq_cfqq_on_rr(cfqq))
713 cfq_add_cfqq_rr(cfqd, cfqq);
716 * check if this request is a better next-serve candidate
718 prev = cfqq->next_rq;
719 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
722 * adjust priority tree position, if ->next_rq changes
724 if (prev != cfqq->next_rq)
725 cfq_prio_tree_add(cfqd, cfqq);
727 BUG_ON(!cfqq->next_rq);
730 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
732 elv_rb_del(&cfqq->sort_list, rq);
733 cfqq->queued[rq_is_sync(rq)]--;
737 static struct request *
738 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
740 struct task_struct *tsk = current;
741 struct cfq_io_context *cic;
742 struct cfq_queue *cfqq;
744 cic = cfq_cic_lookup(cfqd, tsk->io_context);
748 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
750 sector_t sector = bio->bi_sector + bio_sectors(bio);
752 return elv_rb_find(&cfqq->sort_list, sector);
758 static void cfq_activate_request(struct request_queue *q, struct request *rq)
760 struct cfq_data *cfqd = q->elevator->elevator_data;
762 cfqd->rq_in_driver[rq_is_sync(rq)]++;
763 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
766 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
769 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
771 struct cfq_data *cfqd = q->elevator->elevator_data;
772 const int sync = rq_is_sync(rq);
774 WARN_ON(!cfqd->rq_in_driver[sync]);
775 cfqd->rq_in_driver[sync]--;
776 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
780 static void cfq_remove_request(struct request *rq)
782 struct cfq_queue *cfqq = RQ_CFQQ(rq);
784 if (cfqq->next_rq == rq)
785 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
787 list_del_init(&rq->queuelist);
790 cfqq->cfqd->rq_queued--;
791 if (rq_is_meta(rq)) {
792 WARN_ON(!cfqq->meta_pending);
793 cfqq->meta_pending--;
797 static int cfq_merge(struct request_queue *q, struct request **req,
800 struct cfq_data *cfqd = q->elevator->elevator_data;
801 struct request *__rq;
803 __rq = cfq_find_rq_fmerge(cfqd, bio);
804 if (__rq && elv_rq_merge_ok(__rq, bio)) {
806 return ELEVATOR_FRONT_MERGE;
809 return ELEVATOR_NO_MERGE;
812 static void cfq_merged_request(struct request_queue *q, struct request *req,
815 if (type == ELEVATOR_FRONT_MERGE) {
816 struct cfq_queue *cfqq = RQ_CFQQ(req);
818 cfq_reposition_rq_rb(cfqq, req);
823 cfq_merged_requests(struct request_queue *q, struct request *rq,
824 struct request *next)
827 * reposition in fifo if next is older than rq
829 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
830 time_before(next->start_time, rq->start_time))
831 list_move(&rq->queuelist, &next->queuelist);
833 cfq_remove_request(next);
836 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
839 struct cfq_data *cfqd = q->elevator->elevator_data;
840 struct cfq_io_context *cic;
841 struct cfq_queue *cfqq;
844 * Disallow merge of a sync bio into an async request.
846 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
850 * Lookup the cfqq that this bio will be queued with. Allow
851 * merge only if rq is queued there.
853 cic = cfq_cic_lookup(cfqd, current->io_context);
857 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
858 if (cfqq == RQ_CFQQ(rq))
864 static void __cfq_set_active_queue(struct cfq_data *cfqd,
865 struct cfq_queue *cfqq)
868 cfq_log_cfqq(cfqd, cfqq, "set_active");
870 cfqq->slice_dispatch = 0;
872 cfq_clear_cfqq_wait_request(cfqq);
873 cfq_clear_cfqq_must_dispatch(cfqq);
874 cfq_clear_cfqq_must_alloc_slice(cfqq);
875 cfq_clear_cfqq_fifo_expire(cfqq);
876 cfq_mark_cfqq_slice_new(cfqq);
878 del_timer(&cfqd->idle_slice_timer);
881 cfqd->active_queue = cfqq;
885 * current cfqq expired its slice (or was too idle), select new one
888 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
891 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
893 if (cfq_cfqq_wait_request(cfqq))
894 del_timer(&cfqd->idle_slice_timer);
896 cfq_clear_cfqq_wait_request(cfqq);
899 * store what was left of this slice, if the queue idled/timed out
901 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
902 cfqq->slice_resid = cfqq->slice_end - jiffies;
903 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
906 cfq_resort_rr_list(cfqd, cfqq);
908 if (cfqq == cfqd->active_queue)
909 cfqd->active_queue = NULL;
911 if (cfqd->active_cic) {
912 put_io_context(cfqd->active_cic->ioc);
913 cfqd->active_cic = NULL;
917 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
919 struct cfq_queue *cfqq = cfqd->active_queue;
922 __cfq_slice_expired(cfqd, cfqq, timed_out);
926 * Get next queue for service. Unless we have a queue preemption,
927 * we'll simply select the first cfqq in the service tree.
929 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
931 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
934 return cfq_rb_first(&cfqd->service_tree);
938 * Get and set a new active queue for service.
940 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
941 struct cfq_queue *cfqq)
944 cfqq = cfq_get_next_queue(cfqd);
946 cfq_clear_cfqq_coop(cfqq);
949 __cfq_set_active_queue(cfqd, cfqq);
953 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
956 if (blk_rq_pos(rq) >= cfqd->last_position)
957 return blk_rq_pos(rq) - cfqd->last_position;
959 return cfqd->last_position - blk_rq_pos(rq);
962 #define CIC_SEEK_THR 8 * 1024
963 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
965 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
967 struct cfq_io_context *cic = cfqd->active_cic;
968 sector_t sdist = cic->seek_mean;
970 if (!sample_valid(cic->seek_samples))
971 sdist = CIC_SEEK_THR;
973 return cfq_dist_from_last(cfqd, rq) <= sdist;
976 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
977 struct cfq_queue *cur_cfqq)
979 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
980 struct rb_node *parent, *node;
981 struct cfq_queue *__cfqq;
982 sector_t sector = cfqd->last_position;
984 if (RB_EMPTY_ROOT(root))
988 * First, if we find a request starting at the end of the last
989 * request, choose it.
991 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
996 * If the exact sector wasn't found, the parent of the NULL leaf
997 * will contain the closest sector.
999 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1000 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1003 if (blk_rq_pos(__cfqq->next_rq) < sector)
1004 node = rb_next(&__cfqq->p_node);
1006 node = rb_prev(&__cfqq->p_node);
1010 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1011 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1019 * cur_cfqq - passed in so that we don't decide that the current queue is
1020 * closely cooperating with itself.
1022 * So, basically we're assuming that that cur_cfqq has dispatched at least
1023 * one request, and that cfqd->last_position reflects a position on the disk
1024 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1027 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1028 struct cfq_queue *cur_cfqq,
1031 struct cfq_queue *cfqq;
1034 * A valid cfq_io_context is necessary to compare requests against
1035 * the seek_mean of the current cfqq.
1037 if (!cfqd->active_cic)
1041 * We should notice if some of the queues are cooperating, eg
1042 * working closely on the same area of the disk. In that case,
1043 * we can group them together and don't waste time idling.
1045 cfqq = cfqq_close(cfqd, cur_cfqq);
1049 if (cfq_cfqq_coop(cfqq))
1053 cfq_mark_cfqq_coop(cfqq);
1057 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1059 struct cfq_queue *cfqq = cfqd->active_queue;
1060 struct cfq_io_context *cic;
1064 * SSD device without seek penalty, disable idling. But only do so
1065 * for devices that support queuing, otherwise we still have a problem
1066 * with sync vs async workloads.
1068 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1071 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1072 WARN_ON(cfq_cfqq_slice_new(cfqq));
1075 * idle is disabled, either manually or by past process history
1077 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1081 * still requests with the driver, don't idle
1083 if (rq_in_driver(cfqd))
1087 * task has exited, don't wait
1089 cic = cfqd->active_cic;
1090 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1093 cfq_mark_cfqq_wait_request(cfqq);
1096 * we don't want to idle for seeks, but we do want to allow
1097 * fair distribution of slice time for a process doing back-to-back
1098 * seeks. so allow a little bit of time for him to submit a new rq
1100 sl = cfqd->cfq_slice_idle;
1101 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1102 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1104 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1105 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1109 * Move request from internal lists to the request queue dispatch list.
1111 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1113 struct cfq_data *cfqd = q->elevator->elevator_data;
1114 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1116 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1118 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1119 cfq_remove_request(rq);
1121 elv_dispatch_sort(q, rq);
1123 if (cfq_cfqq_sync(cfqq))
1124 cfqd->sync_flight++;
1128 * return expired entry, or NULL to just start from scratch in rbtree
1130 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1132 struct cfq_data *cfqd = cfqq->cfqd;
1136 if (cfq_cfqq_fifo_expire(cfqq))
1139 cfq_mark_cfqq_fifo_expire(cfqq);
1141 if (list_empty(&cfqq->fifo))
1144 fifo = cfq_cfqq_sync(cfqq);
1145 rq = rq_entry_fifo(cfqq->fifo.next);
1147 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
1150 cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
1155 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1157 const int base_rq = cfqd->cfq_slice_async_rq;
1159 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1161 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1165 * Select a queue for service. If we have a current active queue,
1166 * check whether to continue servicing it, or retrieve and set a new one.
1168 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1170 struct cfq_queue *cfqq, *new_cfqq = NULL;
1172 cfqq = cfqd->active_queue;
1177 * The active queue has run out of time, expire it and select new.
1179 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1183 * The active queue has requests and isn't expired, allow it to
1186 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1190 * If another queue has a request waiting within our mean seek
1191 * distance, let it run. The expire code will check for close
1192 * cooperators and put the close queue at the front of the service
1195 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1200 * No requests pending. If the active queue still has requests in
1201 * flight or is idling for a new request, allow either of these
1202 * conditions to happen (or time out) before selecting a new queue.
1204 if (timer_pending(&cfqd->idle_slice_timer) ||
1205 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1211 cfq_slice_expired(cfqd, 0);
1213 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1218 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1222 while (cfqq->next_rq) {
1223 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1227 BUG_ON(!list_empty(&cfqq->fifo));
1232 * Drain our current requests. Used for barriers and when switching
1233 * io schedulers on-the-fly.
1235 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1237 struct cfq_queue *cfqq;
1240 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1241 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1243 cfq_slice_expired(cfqd, 0);
1245 BUG_ON(cfqd->busy_queues);
1247 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1252 * Dispatch a request from cfqq, moving them to the request queue
1255 static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1259 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1262 * follow expired path, else get first next available
1264 rq = cfq_check_fifo(cfqq);
1269 * insert request into driver dispatch list
1271 cfq_dispatch_insert(cfqd->queue, rq);
1273 if (!cfqd->active_cic) {
1274 struct cfq_io_context *cic = RQ_CIC(rq);
1276 atomic_long_inc(&cic->ioc->refcount);
1277 cfqd->active_cic = cic;
1282 * Find the cfqq that we need to service and move a request from that to the
1285 static int cfq_dispatch_requests(struct request_queue *q, int force)
1287 struct cfq_data *cfqd = q->elevator->elevator_data;
1288 struct cfq_queue *cfqq;
1289 unsigned int max_dispatch;
1291 if (!cfqd->busy_queues)
1294 if (unlikely(force))
1295 return cfq_forced_dispatch(cfqd);
1297 cfqq = cfq_select_queue(cfqd);
1302 * Drain async requests before we start sync IO
1304 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1308 * If this is an async queue and we have sync IO in flight, let it wait
1310 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1313 max_dispatch = cfqd->cfq_quantum;
1314 if (cfq_class_idle(cfqq))
1318 * Does this cfqq already have too much IO in flight?
1320 if (cfqq->dispatched >= max_dispatch) {
1322 * idle queue must always only have a single IO in flight
1324 if (cfq_class_idle(cfqq))
1328 * We have other queues, don't allow more IO from this one
1330 if (cfqd->busy_queues > 1)
1334 * Sole queue user, allow bigger slice
1340 * Async queues must wait a bit before being allowed dispatch.
1341 * We also ramp up the dispatch depth gradually for async IO,
1342 * based on the last sync IO we serviced
1344 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
1345 unsigned long last_sync = jiffies - cfqd->last_end_sync_rq;
1349 * must wait a bit longer
1351 if (last_sync < cfq_slice_sync) {
1352 cfq_schedule_dispatch(cfqd, cfq_slice_sync - last_sync);
1356 depth = last_sync / cfq_slice_sync;
1357 if (depth < max_dispatch)
1358 max_dispatch = depth;
1361 if (cfqq->dispatched >= max_dispatch)
1365 * Dispatch a request from this cfqq
1367 cfq_dispatch_request(cfqd, cfqq);
1368 cfqq->slice_dispatch++;
1369 cfq_clear_cfqq_must_dispatch(cfqq);
1372 * expire an async queue immediately if it has used up its slice. idle
1373 * queue always expire after 1 dispatch round.
1375 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1376 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1377 cfq_class_idle(cfqq))) {
1378 cfqq->slice_end = jiffies + 1;
1379 cfq_slice_expired(cfqd, 0);
1382 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
1387 * task holds one reference to the queue, dropped when task exits. each rq
1388 * in-flight on this queue also holds a reference, dropped when rq is freed.
1390 * queue lock must be held here.
1392 static void cfq_put_queue(struct cfq_queue *cfqq)
1394 struct cfq_data *cfqd = cfqq->cfqd;
1396 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1398 if (!atomic_dec_and_test(&cfqq->ref))
1401 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1402 BUG_ON(rb_first(&cfqq->sort_list));
1403 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1404 BUG_ON(cfq_cfqq_on_rr(cfqq));
1406 if (unlikely(cfqd->active_queue == cfqq)) {
1407 __cfq_slice_expired(cfqd, cfqq, 0);
1408 cfq_schedule_dispatch(cfqd, 0);
1411 kmem_cache_free(cfq_pool, cfqq);
1415 * Must always be called with the rcu_read_lock() held
1418 __call_for_each_cic(struct io_context *ioc,
1419 void (*func)(struct io_context *, struct cfq_io_context *))
1421 struct cfq_io_context *cic;
1422 struct hlist_node *n;
1424 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1429 * Call func for each cic attached to this ioc.
1432 call_for_each_cic(struct io_context *ioc,
1433 void (*func)(struct io_context *, struct cfq_io_context *))
1436 __call_for_each_cic(ioc, func);
1440 static void cfq_cic_free_rcu(struct rcu_head *head)
1442 struct cfq_io_context *cic;
1444 cic = container_of(head, struct cfq_io_context, rcu_head);
1446 kmem_cache_free(cfq_ioc_pool, cic);
1447 elv_ioc_count_dec(cfq_ioc_count);
1451 * CFQ scheduler is exiting, grab exit lock and check
1452 * the pending io context count. If it hits zero,
1453 * complete ioc_gone and set it back to NULL
1455 spin_lock(&ioc_gone_lock);
1456 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
1460 spin_unlock(&ioc_gone_lock);
1464 static void cfq_cic_free(struct cfq_io_context *cic)
1466 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1469 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1471 unsigned long flags;
1473 BUG_ON(!cic->dead_key);
1475 spin_lock_irqsave(&ioc->lock, flags);
1476 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1477 hlist_del_rcu(&cic->cic_list);
1478 spin_unlock_irqrestore(&ioc->lock, flags);
1484 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1485 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1486 * and ->trim() which is called with the task lock held
1488 static void cfq_free_io_context(struct io_context *ioc)
1491 * ioc->refcount is zero here, or we are called from elv_unregister(),
1492 * so no more cic's are allowed to be linked into this ioc. So it
1493 * should be ok to iterate over the known list, we will see all cic's
1494 * since no new ones are added.
1496 __call_for_each_cic(ioc, cic_free_func);
1499 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1501 if (unlikely(cfqq == cfqd->active_queue)) {
1502 __cfq_slice_expired(cfqd, cfqq, 0);
1503 cfq_schedule_dispatch(cfqd, 0);
1506 cfq_put_queue(cfqq);
1509 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1510 struct cfq_io_context *cic)
1512 struct io_context *ioc = cic->ioc;
1514 list_del_init(&cic->queue_list);
1517 * Make sure key == NULL is seen for dead queues
1520 cic->dead_key = (unsigned long) cic->key;
1523 if (ioc->ioc_data == cic)
1524 rcu_assign_pointer(ioc->ioc_data, NULL);
1526 if (cic->cfqq[BLK_RW_ASYNC]) {
1527 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1528 cic->cfqq[BLK_RW_ASYNC] = NULL;
1531 if (cic->cfqq[BLK_RW_SYNC]) {
1532 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1533 cic->cfqq[BLK_RW_SYNC] = NULL;
1537 static void cfq_exit_single_io_context(struct io_context *ioc,
1538 struct cfq_io_context *cic)
1540 struct cfq_data *cfqd = cic->key;
1543 struct request_queue *q = cfqd->queue;
1544 unsigned long flags;
1546 spin_lock_irqsave(q->queue_lock, flags);
1549 * Ensure we get a fresh copy of the ->key to prevent
1550 * race between exiting task and queue
1552 smp_read_barrier_depends();
1554 __cfq_exit_single_io_context(cfqd, cic);
1556 spin_unlock_irqrestore(q->queue_lock, flags);
1561 * The process that ioc belongs to has exited, we need to clean up
1562 * and put the internal structures we have that belongs to that process.
1564 static void cfq_exit_io_context(struct io_context *ioc)
1566 call_for_each_cic(ioc, cfq_exit_single_io_context);
1569 static struct cfq_io_context *
1570 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1572 struct cfq_io_context *cic;
1574 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1577 cic->last_end_request = jiffies;
1578 INIT_LIST_HEAD(&cic->queue_list);
1579 INIT_HLIST_NODE(&cic->cic_list);
1580 cic->dtor = cfq_free_io_context;
1581 cic->exit = cfq_exit_io_context;
1582 elv_ioc_count_inc(cfq_ioc_count);
1588 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1590 struct task_struct *tsk = current;
1593 if (!cfq_cfqq_prio_changed(cfqq))
1596 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1597 switch (ioprio_class) {
1599 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1600 case IOPRIO_CLASS_NONE:
1602 * no prio set, inherit CPU scheduling settings
1604 cfqq->ioprio = task_nice_ioprio(tsk);
1605 cfqq->ioprio_class = task_nice_ioclass(tsk);
1607 case IOPRIO_CLASS_RT:
1608 cfqq->ioprio = task_ioprio(ioc);
1609 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1611 case IOPRIO_CLASS_BE:
1612 cfqq->ioprio = task_ioprio(ioc);
1613 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1615 case IOPRIO_CLASS_IDLE:
1616 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1618 cfq_clear_cfqq_idle_window(cfqq);
1623 * keep track of original prio settings in case we have to temporarily
1624 * elevate the priority of this queue
1626 cfqq->org_ioprio = cfqq->ioprio;
1627 cfqq->org_ioprio_class = cfqq->ioprio_class;
1628 cfq_clear_cfqq_prio_changed(cfqq);
1631 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1633 struct cfq_data *cfqd = cic->key;
1634 struct cfq_queue *cfqq;
1635 unsigned long flags;
1637 if (unlikely(!cfqd))
1640 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1642 cfqq = cic->cfqq[BLK_RW_ASYNC];
1644 struct cfq_queue *new_cfqq;
1645 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1648 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1649 cfq_put_queue(cfqq);
1653 cfqq = cic->cfqq[BLK_RW_SYNC];
1655 cfq_mark_cfqq_prio_changed(cfqq);
1657 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1660 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1662 call_for_each_cic(ioc, changed_ioprio);
1663 ioc->ioprio_changed = 0;
1666 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1667 pid_t pid, int is_sync)
1669 RB_CLEAR_NODE(&cfqq->rb_node);
1670 RB_CLEAR_NODE(&cfqq->p_node);
1671 INIT_LIST_HEAD(&cfqq->fifo);
1673 atomic_set(&cfqq->ref, 0);
1676 cfq_mark_cfqq_prio_changed(cfqq);
1679 if (!cfq_class_idle(cfqq))
1680 cfq_mark_cfqq_idle_window(cfqq);
1681 cfq_mark_cfqq_sync(cfqq);
1686 static struct cfq_queue *
1687 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1688 struct io_context *ioc, gfp_t gfp_mask)
1690 struct cfq_queue *cfqq, *new_cfqq = NULL;
1691 struct cfq_io_context *cic;
1694 cic = cfq_cic_lookup(cfqd, ioc);
1695 /* cic always exists here */
1696 cfqq = cic_to_cfqq(cic, is_sync);
1699 * Always try a new alloc if we fell back to the OOM cfqq
1700 * originally, since it should just be a temporary situation.
1702 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1707 } else if (gfp_mask & __GFP_WAIT) {
1708 spin_unlock_irq(cfqd->queue->queue_lock);
1709 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1710 gfp_mask | __GFP_ZERO,
1712 spin_lock_irq(cfqd->queue->queue_lock);
1716 cfqq = kmem_cache_alloc_node(cfq_pool,
1717 gfp_mask | __GFP_ZERO,
1722 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1723 cfq_init_prio_data(cfqq, ioc);
1724 cfq_log_cfqq(cfqd, cfqq, "alloced");
1726 cfqq = &cfqd->oom_cfqq;
1730 kmem_cache_free(cfq_pool, new_cfqq);
1735 static struct cfq_queue **
1736 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1738 switch (ioprio_class) {
1739 case IOPRIO_CLASS_RT:
1740 return &cfqd->async_cfqq[0][ioprio];
1741 case IOPRIO_CLASS_BE:
1742 return &cfqd->async_cfqq[1][ioprio];
1743 case IOPRIO_CLASS_IDLE:
1744 return &cfqd->async_idle_cfqq;
1750 static struct cfq_queue *
1751 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1754 const int ioprio = task_ioprio(ioc);
1755 const int ioprio_class = task_ioprio_class(ioc);
1756 struct cfq_queue **async_cfqq = NULL;
1757 struct cfq_queue *cfqq = NULL;
1760 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1765 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1768 * pin the queue now that it's allocated, scheduler exit will prune it
1770 if (!is_sync && !(*async_cfqq)) {
1771 atomic_inc(&cfqq->ref);
1775 atomic_inc(&cfqq->ref);
1780 * We drop cfq io contexts lazily, so we may find a dead one.
1783 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1784 struct cfq_io_context *cic)
1786 unsigned long flags;
1788 WARN_ON(!list_empty(&cic->queue_list));
1790 spin_lock_irqsave(&ioc->lock, flags);
1792 BUG_ON(ioc->ioc_data == cic);
1794 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1795 hlist_del_rcu(&cic->cic_list);
1796 spin_unlock_irqrestore(&ioc->lock, flags);
1801 static struct cfq_io_context *
1802 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1804 struct cfq_io_context *cic;
1805 unsigned long flags;
1814 * we maintain a last-hit cache, to avoid browsing over the tree
1816 cic = rcu_dereference(ioc->ioc_data);
1817 if (cic && cic->key == cfqd) {
1823 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1827 /* ->key must be copied to avoid race with cfq_exit_queue() */
1830 cfq_drop_dead_cic(cfqd, ioc, cic);
1835 spin_lock_irqsave(&ioc->lock, flags);
1836 rcu_assign_pointer(ioc->ioc_data, cic);
1837 spin_unlock_irqrestore(&ioc->lock, flags);
1845 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1846 * the process specific cfq io context when entered from the block layer.
1847 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1849 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1850 struct cfq_io_context *cic, gfp_t gfp_mask)
1852 unsigned long flags;
1855 ret = radix_tree_preload(gfp_mask);
1860 spin_lock_irqsave(&ioc->lock, flags);
1861 ret = radix_tree_insert(&ioc->radix_root,
1862 (unsigned long) cfqd, cic);
1864 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1865 spin_unlock_irqrestore(&ioc->lock, flags);
1867 radix_tree_preload_end();
1870 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1871 list_add(&cic->queue_list, &cfqd->cic_list);
1872 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1877 printk(KERN_ERR "cfq: cic link failed!\n");
1883 * Setup general io context and cfq io context. There can be several cfq
1884 * io contexts per general io context, if this process is doing io to more
1885 * than one device managed by cfq.
1887 static struct cfq_io_context *
1888 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1890 struct io_context *ioc = NULL;
1891 struct cfq_io_context *cic;
1893 might_sleep_if(gfp_mask & __GFP_WAIT);
1895 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1899 cic = cfq_cic_lookup(cfqd, ioc);
1903 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1907 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1911 smp_read_barrier_depends();
1912 if (unlikely(ioc->ioprio_changed))
1913 cfq_ioc_set_ioprio(ioc);
1919 put_io_context(ioc);
1924 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1926 unsigned long elapsed = jiffies - cic->last_end_request;
1927 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1929 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1930 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1931 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1935 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1941 if (!cic->last_request_pos)
1943 else if (cic->last_request_pos < blk_rq_pos(rq))
1944 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1946 sdist = cic->last_request_pos - blk_rq_pos(rq);
1949 * Don't allow the seek distance to get too large from the
1950 * odd fragment, pagein, etc
1952 if (cic->seek_samples <= 60) /* second&third seek */
1953 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1955 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1957 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1958 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1959 total = cic->seek_total + (cic->seek_samples/2);
1960 do_div(total, cic->seek_samples);
1961 cic->seek_mean = (sector_t)total;
1965 * Disable idle window if the process thinks too long or seeks so much that
1969 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1970 struct cfq_io_context *cic)
1972 int old_idle, enable_idle;
1975 * Don't idle for async or idle io prio class
1977 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1980 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1982 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1983 (!cfqd->cfq_latency && cfqd->hw_tag && CIC_SEEKY(cic)))
1985 else if (sample_valid(cic->ttime_samples)) {
1986 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1992 if (old_idle != enable_idle) {
1993 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
1995 cfq_mark_cfqq_idle_window(cfqq);
1997 cfq_clear_cfqq_idle_window(cfqq);
2002 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2003 * no or if we aren't sure, a 1 will cause a preempt.
2006 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
2009 struct cfq_queue *cfqq;
2011 cfqq = cfqd->active_queue;
2015 if (cfq_slice_used(cfqq))
2018 if (cfq_class_idle(new_cfqq))
2021 if (cfq_class_idle(cfqq))
2025 * if the new request is sync, but the currently running queue is
2026 * not, let the sync request have priority.
2028 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2032 * So both queues are sync. Let the new request get disk time if
2033 * it's a metadata request and the current queue is doing regular IO.
2035 if (rq_is_meta(rq) && !cfqq->meta_pending)
2039 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2041 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2044 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2048 * if this request is as-good as one we would expect from the
2049 * current cfqq, let it preempt
2051 if (cfq_rq_close(cfqd, rq))
2058 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2059 * let it have half of its nominal slice.
2061 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2063 cfq_log_cfqq(cfqd, cfqq, "preempt");
2064 cfq_slice_expired(cfqd, 1);
2067 * Put the new queue at the front of the of the current list,
2068 * so we know that it will be selected next.
2070 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2072 cfq_service_tree_add(cfqd, cfqq, 1);
2074 cfqq->slice_end = 0;
2075 cfq_mark_cfqq_slice_new(cfqq);
2079 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2080 * something we should do about it
2083 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2086 struct cfq_io_context *cic = RQ_CIC(rq);
2090 cfqq->meta_pending++;
2092 cfq_update_io_thinktime(cfqd, cic);
2093 cfq_update_io_seektime(cfqd, cic, rq);
2094 cfq_update_idle_window(cfqd, cfqq, cic);
2096 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2098 if (cfqq == cfqd->active_queue) {
2100 * Remember that we saw a request from this process, but
2101 * don't start queuing just yet. Otherwise we risk seeing lots
2102 * of tiny requests, because we disrupt the normal plugging
2103 * and merging. If the request is already larger than a single
2104 * page, let it rip immediately. For that case we assume that
2105 * merging is already done. Ditto for a busy system that
2106 * has other work pending, don't risk delaying until the
2107 * idle timer unplug to continue working.
2109 if (cfq_cfqq_wait_request(cfqq)) {
2110 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2111 cfqd->busy_queues > 1) {
2112 del_timer(&cfqd->idle_slice_timer);
2113 __blk_run_queue(cfqd->queue);
2115 cfq_mark_cfqq_must_dispatch(cfqq);
2117 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2119 * not the active queue - expire current slice if it is
2120 * idle and has expired it's mean thinktime or this new queue
2121 * has some old slice time left and is of higher priority or
2122 * this new queue is RT and the current one is BE
2124 cfq_preempt_queue(cfqd, cfqq);
2125 __blk_run_queue(cfqd->queue);
2129 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2131 struct cfq_data *cfqd = q->elevator->elevator_data;
2132 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2134 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2135 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2139 list_add_tail(&rq->queuelist, &cfqq->fifo);
2141 cfq_rq_enqueued(cfqd, cfqq, rq);
2145 * Update hw_tag based on peak queue depth over 50 samples under
2148 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2150 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2151 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
2153 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2154 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2157 if (cfqd->hw_tag_samples++ < 50)
2160 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2165 cfqd->hw_tag_samples = 0;
2166 cfqd->rq_in_driver_peak = 0;
2169 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2171 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2172 struct cfq_data *cfqd = cfqq->cfqd;
2173 const int sync = rq_is_sync(rq);
2177 cfq_log_cfqq(cfqd, cfqq, "complete");
2179 cfq_update_hw_tag(cfqd);
2181 WARN_ON(!cfqd->rq_in_driver[sync]);
2182 WARN_ON(!cfqq->dispatched);
2183 cfqd->rq_in_driver[sync]--;
2186 if (cfq_cfqq_sync(cfqq))
2187 cfqd->sync_flight--;
2190 RQ_CIC(rq)->last_end_request = now;
2191 cfqd->last_end_sync_rq = now;
2195 * If this is the active queue, check if it needs to be expired,
2196 * or if we want to idle in case it has no pending requests.
2198 if (cfqd->active_queue == cfqq) {
2199 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2201 if (cfq_cfqq_slice_new(cfqq)) {
2202 cfq_set_prio_slice(cfqd, cfqq);
2203 cfq_clear_cfqq_slice_new(cfqq);
2206 * If there are no requests waiting in this queue, and
2207 * there are other queues ready to issue requests, AND
2208 * those other queues are issuing requests within our
2209 * mean seek distance, give them a chance to run instead
2212 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2213 cfq_slice_expired(cfqd, 1);
2214 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2215 sync && !rq_noidle(rq))
2216 cfq_arm_slice_timer(cfqd);
2219 if (!rq_in_driver(cfqd))
2220 cfq_schedule_dispatch(cfqd, 0);
2224 * we temporarily boost lower priority queues if they are holding fs exclusive
2225 * resources. they are boosted to normal prio (CLASS_BE/4)
2227 static void cfq_prio_boost(struct cfq_queue *cfqq)
2229 if (has_fs_excl()) {
2231 * boost idle prio on transactions that would lock out other
2232 * users of the filesystem
2234 if (cfq_class_idle(cfqq))
2235 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2236 if (cfqq->ioprio > IOPRIO_NORM)
2237 cfqq->ioprio = IOPRIO_NORM;
2240 * check if we need to unboost the queue
2242 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2243 cfqq->ioprio_class = cfqq->org_ioprio_class;
2244 if (cfqq->ioprio != cfqq->org_ioprio)
2245 cfqq->ioprio = cfqq->org_ioprio;
2249 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2251 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
2252 cfq_mark_cfqq_must_alloc_slice(cfqq);
2253 return ELV_MQUEUE_MUST;
2256 return ELV_MQUEUE_MAY;
2259 static int cfq_may_queue(struct request_queue *q, int rw)
2261 struct cfq_data *cfqd = q->elevator->elevator_data;
2262 struct task_struct *tsk = current;
2263 struct cfq_io_context *cic;
2264 struct cfq_queue *cfqq;
2267 * don't force setup of a queue from here, as a call to may_queue
2268 * does not necessarily imply that a request actually will be queued.
2269 * so just lookup a possibly existing queue, or return 'may queue'
2272 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2274 return ELV_MQUEUE_MAY;
2276 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2278 cfq_init_prio_data(cfqq, cic->ioc);
2279 cfq_prio_boost(cfqq);
2281 return __cfq_may_queue(cfqq);
2284 return ELV_MQUEUE_MAY;
2288 * queue lock held here
2290 static void cfq_put_request(struct request *rq)
2292 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2295 const int rw = rq_data_dir(rq);
2297 BUG_ON(!cfqq->allocated[rw]);
2298 cfqq->allocated[rw]--;
2300 put_io_context(RQ_CIC(rq)->ioc);
2302 rq->elevator_private = NULL;
2303 rq->elevator_private2 = NULL;
2305 cfq_put_queue(cfqq);
2310 * Allocate cfq data structures associated with this request.
2313 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2315 struct cfq_data *cfqd = q->elevator->elevator_data;
2316 struct cfq_io_context *cic;
2317 const int rw = rq_data_dir(rq);
2318 const int is_sync = rq_is_sync(rq);
2319 struct cfq_queue *cfqq;
2320 unsigned long flags;
2322 might_sleep_if(gfp_mask & __GFP_WAIT);
2324 cic = cfq_get_io_context(cfqd, gfp_mask);
2326 spin_lock_irqsave(q->queue_lock, flags);
2331 cfqq = cic_to_cfqq(cic, is_sync);
2332 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2333 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2334 cic_set_cfqq(cic, cfqq, is_sync);
2337 cfqq->allocated[rw]++;
2338 atomic_inc(&cfqq->ref);
2340 spin_unlock_irqrestore(q->queue_lock, flags);
2342 rq->elevator_private = cic;
2343 rq->elevator_private2 = cfqq;
2348 put_io_context(cic->ioc);
2350 cfq_schedule_dispatch(cfqd, 0);
2351 spin_unlock_irqrestore(q->queue_lock, flags);
2352 cfq_log(cfqd, "set_request fail");
2356 static void cfq_kick_queue(struct work_struct *work)
2358 struct cfq_data *cfqd =
2359 container_of(work, struct cfq_data, unplug_work.work);
2360 struct request_queue *q = cfqd->queue;
2362 spin_lock_irq(q->queue_lock);
2363 __blk_run_queue(cfqd->queue);
2364 spin_unlock_irq(q->queue_lock);
2368 * Timer running if the active_queue is currently idling inside its time slice
2370 static void cfq_idle_slice_timer(unsigned long data)
2372 struct cfq_data *cfqd = (struct cfq_data *) data;
2373 struct cfq_queue *cfqq;
2374 unsigned long flags;
2377 cfq_log(cfqd, "idle timer fired");
2379 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2381 cfqq = cfqd->active_queue;
2386 * We saw a request before the queue expired, let it through
2388 if (cfq_cfqq_must_dispatch(cfqq))
2394 if (cfq_slice_used(cfqq))
2398 * only expire and reinvoke request handler, if there are
2399 * other queues with pending requests
2401 if (!cfqd->busy_queues)
2405 * not expired and it has a request pending, let it dispatch
2407 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2411 cfq_slice_expired(cfqd, timed_out);
2413 cfq_schedule_dispatch(cfqd, 0);
2415 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2418 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2420 del_timer_sync(&cfqd->idle_slice_timer);
2421 cancel_delayed_work_sync(&cfqd->unplug_work);
2424 static void cfq_put_async_queues(struct cfq_data *cfqd)
2428 for (i = 0; i < IOPRIO_BE_NR; i++) {
2429 if (cfqd->async_cfqq[0][i])
2430 cfq_put_queue(cfqd->async_cfqq[0][i]);
2431 if (cfqd->async_cfqq[1][i])
2432 cfq_put_queue(cfqd->async_cfqq[1][i]);
2435 if (cfqd->async_idle_cfqq)
2436 cfq_put_queue(cfqd->async_idle_cfqq);
2439 static void cfq_exit_queue(struct elevator_queue *e)
2441 struct cfq_data *cfqd = e->elevator_data;
2442 struct request_queue *q = cfqd->queue;
2444 cfq_shutdown_timer_wq(cfqd);
2446 spin_lock_irq(q->queue_lock);
2448 if (cfqd->active_queue)
2449 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2451 while (!list_empty(&cfqd->cic_list)) {
2452 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2453 struct cfq_io_context,
2456 __cfq_exit_single_io_context(cfqd, cic);
2459 cfq_put_async_queues(cfqd);
2461 spin_unlock_irq(q->queue_lock);
2463 cfq_shutdown_timer_wq(cfqd);
2468 static void *cfq_init_queue(struct request_queue *q)
2470 struct cfq_data *cfqd;
2473 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2477 cfqd->service_tree = CFQ_RB_ROOT;
2480 * Not strictly needed (since RB_ROOT just clears the node and we
2481 * zeroed cfqd on alloc), but better be safe in case someone decides
2482 * to add magic to the rb code
2484 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2485 cfqd->prio_trees[i] = RB_ROOT;
2488 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2489 * Grab a permanent reference to it, so that the normal code flow
2490 * will not attempt to free it.
2492 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2493 atomic_inc(&cfqd->oom_cfqq.ref);
2495 INIT_LIST_HEAD(&cfqd->cic_list);
2499 init_timer(&cfqd->idle_slice_timer);
2500 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2501 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2503 INIT_DELAYED_WORK(&cfqd->unplug_work, cfq_kick_queue);
2505 cfqd->cfq_quantum = cfq_quantum;
2506 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2507 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2508 cfqd->cfq_back_max = cfq_back_max;
2509 cfqd->cfq_back_penalty = cfq_back_penalty;
2510 cfqd->cfq_slice[0] = cfq_slice_async;
2511 cfqd->cfq_slice[1] = cfq_slice_sync;
2512 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2513 cfqd->cfq_slice_idle = cfq_slice_idle;
2514 cfqd->cfq_latency = 1;
2516 cfqd->last_end_sync_rq = jiffies;
2520 static void cfq_slab_kill(void)
2523 * Caller already ensured that pending RCU callbacks are completed,
2524 * so we should have no busy allocations at this point.
2527 kmem_cache_destroy(cfq_pool);
2529 kmem_cache_destroy(cfq_ioc_pool);
2532 static int __init cfq_slab_setup(void)
2534 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2538 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2549 * sysfs parts below -->
2552 cfq_var_show(unsigned int var, char *page)
2554 return sprintf(page, "%d\n", var);
2558 cfq_var_store(unsigned int *var, const char *page, size_t count)
2560 char *p = (char *) page;
2562 *var = simple_strtoul(p, &p, 10);
2566 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2567 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2569 struct cfq_data *cfqd = e->elevator_data; \
2570 unsigned int __data = __VAR; \
2572 __data = jiffies_to_msecs(__data); \
2573 return cfq_var_show(__data, (page)); \
2575 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2576 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2577 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2578 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2579 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2580 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2581 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2582 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2583 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2584 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
2585 #undef SHOW_FUNCTION
2587 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2588 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2590 struct cfq_data *cfqd = e->elevator_data; \
2591 unsigned int __data; \
2592 int ret = cfq_var_store(&__data, (page), count); \
2593 if (__data < (MIN)) \
2595 else if (__data > (MAX)) \
2598 *(__PTR) = msecs_to_jiffies(__data); \
2600 *(__PTR) = __data; \
2603 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2604 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2606 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2608 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2609 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2611 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2612 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2613 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2614 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2616 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
2617 #undef STORE_FUNCTION
2619 #define CFQ_ATTR(name) \
2620 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2622 static struct elv_fs_entry cfq_attrs[] = {
2624 CFQ_ATTR(fifo_expire_sync),
2625 CFQ_ATTR(fifo_expire_async),
2626 CFQ_ATTR(back_seek_max),
2627 CFQ_ATTR(back_seek_penalty),
2628 CFQ_ATTR(slice_sync),
2629 CFQ_ATTR(slice_async),
2630 CFQ_ATTR(slice_async_rq),
2631 CFQ_ATTR(slice_idle),
2632 CFQ_ATTR(low_latency),
2636 static struct elevator_type iosched_cfq = {
2638 .elevator_merge_fn = cfq_merge,
2639 .elevator_merged_fn = cfq_merged_request,
2640 .elevator_merge_req_fn = cfq_merged_requests,
2641 .elevator_allow_merge_fn = cfq_allow_merge,
2642 .elevator_dispatch_fn = cfq_dispatch_requests,
2643 .elevator_add_req_fn = cfq_insert_request,
2644 .elevator_activate_req_fn = cfq_activate_request,
2645 .elevator_deactivate_req_fn = cfq_deactivate_request,
2646 .elevator_queue_empty_fn = cfq_queue_empty,
2647 .elevator_completed_req_fn = cfq_completed_request,
2648 .elevator_former_req_fn = elv_rb_former_request,
2649 .elevator_latter_req_fn = elv_rb_latter_request,
2650 .elevator_set_req_fn = cfq_set_request,
2651 .elevator_put_req_fn = cfq_put_request,
2652 .elevator_may_queue_fn = cfq_may_queue,
2653 .elevator_init_fn = cfq_init_queue,
2654 .elevator_exit_fn = cfq_exit_queue,
2655 .trim = cfq_free_io_context,
2657 .elevator_attrs = cfq_attrs,
2658 .elevator_name = "cfq",
2659 .elevator_owner = THIS_MODULE,
2662 static int __init cfq_init(void)
2665 * could be 0 on HZ < 1000 setups
2667 if (!cfq_slice_async)
2668 cfq_slice_async = 1;
2669 if (!cfq_slice_idle)
2672 if (cfq_slab_setup())
2675 elv_register(&iosched_cfq);
2680 static void __exit cfq_exit(void)
2682 DECLARE_COMPLETION_ONSTACK(all_gone);
2683 elv_unregister(&iosched_cfq);
2684 ioc_gone = &all_gone;
2685 /* ioc_gone's update must be visible before reading ioc_count */
2689 * this also protects us from entering cfq_slab_kill() with
2690 * pending RCU callbacks
2692 if (elv_ioc_count_read(cfq_ioc_count))
2693 wait_for_completion(&all_gone);
2697 module_init(cfq_init);
2698 module_exit(cfq_exit);
2700 MODULE_AUTHOR("Jens Axboe");
2701 MODULE_LICENSE("GPL");
2702 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");