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;
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)
273 if (cfqd->busy_queues) {
274 cfq_log(cfqd, "schedule dispatch");
275 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
279 static int cfq_queue_empty(struct request_queue *q)
281 struct cfq_data *cfqd = q->elevator->elevator_data;
283 return !cfqd->busy_queues;
287 * Scale schedule slice based on io priority. Use the sync time slice only
288 * if a queue is marked sync and has sync io queued. A sync queue with async
289 * io only, should not get full sync slice length.
291 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
294 const int base_slice = cfqd->cfq_slice[sync];
296 WARN_ON(prio >= IOPRIO_BE_NR);
298 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
302 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
304 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
308 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
310 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
311 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
315 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
316 * isn't valid until the first request from the dispatch is activated
317 * and the slice time set.
319 static inline int cfq_slice_used(struct cfq_queue *cfqq)
321 if (cfq_cfqq_slice_new(cfqq))
323 if (time_before(jiffies, cfqq->slice_end))
330 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
331 * We choose the request that is closest to the head right now. Distance
332 * behind the head is penalized and only allowed to a certain extent.
334 static struct request *
335 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
337 sector_t last, s1, s2, d1 = 0, d2 = 0;
338 unsigned long back_max;
339 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
340 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
341 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
343 if (rq1 == NULL || rq1 == rq2)
348 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
350 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
352 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
354 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
357 s1 = blk_rq_pos(rq1);
358 s2 = blk_rq_pos(rq2);
360 last = cfqd->last_position;
363 * by definition, 1KiB is 2 sectors
365 back_max = cfqd->cfq_back_max * 2;
368 * Strict one way elevator _except_ in the case where we allow
369 * short backward seeks which are biased as twice the cost of a
370 * similar forward seek.
374 else if (s1 + back_max >= last)
375 d1 = (last - s1) * cfqd->cfq_back_penalty;
377 wrap |= CFQ_RQ1_WRAP;
381 else if (s2 + back_max >= last)
382 d2 = (last - s2) * cfqd->cfq_back_penalty;
384 wrap |= CFQ_RQ2_WRAP;
386 /* Found required data */
389 * By doing switch() on the bit mask "wrap" we avoid having to
390 * check two variables for all permutations: --> faster!
393 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
409 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
412 * Since both rqs are wrapped,
413 * start with the one that's further behind head
414 * (--> only *one* back seek required),
415 * since back seek takes more time than forward.
425 * The below is leftmost cache rbtree addon
427 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
430 root->left = rb_first(&root->rb);
433 return rb_entry(root->left, struct cfq_queue, rb_node);
438 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
444 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
448 rb_erase_init(n, &root->rb);
452 * would be nice to take fifo expire time into account as well
454 static struct request *
455 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
456 struct request *last)
458 struct rb_node *rbnext = rb_next(&last->rb_node);
459 struct rb_node *rbprev = rb_prev(&last->rb_node);
460 struct request *next = NULL, *prev = NULL;
462 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
465 prev = rb_entry_rq(rbprev);
468 next = rb_entry_rq(rbnext);
470 rbnext = rb_first(&cfqq->sort_list);
471 if (rbnext && rbnext != &last->rb_node)
472 next = rb_entry_rq(rbnext);
475 return cfq_choose_req(cfqd, next, prev);
478 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
479 struct cfq_queue *cfqq)
482 * just an approximation, should be ok.
484 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
485 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
489 * The cfqd->service_tree holds all pending cfq_queue's that have
490 * requests waiting to be processed. It is sorted in the order that
491 * we will service the queues.
493 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
496 struct rb_node **p, *parent;
497 struct cfq_queue *__cfqq;
498 unsigned long rb_key;
501 if (cfq_class_idle(cfqq)) {
502 rb_key = CFQ_IDLE_DELAY;
503 parent = rb_last(&cfqd->service_tree.rb);
504 if (parent && parent != &cfqq->rb_node) {
505 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
506 rb_key += __cfqq->rb_key;
509 } else if (!add_front) {
510 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
511 rb_key += cfqq->slice_resid;
512 cfqq->slice_resid = 0;
515 __cfqq = cfq_rb_first(&cfqd->service_tree);
516 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
519 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
521 * same position, nothing more to do
523 if (rb_key == cfqq->rb_key)
526 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
531 p = &cfqd->service_tree.rb.rb_node;
536 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
539 * sort RT queues first, we always want to give
540 * preference to them. IDLE queues goes to the back.
541 * after that, sort on the next service time.
543 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
545 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
547 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
549 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
551 else if (time_before(rb_key, __cfqq->rb_key))
556 if (n == &(*p)->rb_right)
563 cfqd->service_tree.left = &cfqq->rb_node;
565 cfqq->rb_key = rb_key;
566 rb_link_node(&cfqq->rb_node, parent, p);
567 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
570 static struct cfq_queue *
571 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
572 sector_t sector, struct rb_node **ret_parent,
573 struct rb_node ***rb_link)
575 struct rb_node **p, *parent;
576 struct cfq_queue *cfqq = NULL;
584 cfqq = rb_entry(parent, struct cfq_queue, p_node);
587 * Sort strictly based on sector. Smallest to the left,
588 * largest to the right.
590 if (sector > blk_rq_pos(cfqq->next_rq))
592 else if (sector < blk_rq_pos(cfqq->next_rq))
600 *ret_parent = parent;
606 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
608 struct rb_node **p, *parent;
609 struct cfq_queue *__cfqq;
612 rb_erase(&cfqq->p_node, cfqq->p_root);
616 if (cfq_class_idle(cfqq))
621 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
622 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
623 blk_rq_pos(cfqq->next_rq), &parent, &p);
625 rb_link_node(&cfqq->p_node, parent, p);
626 rb_insert_color(&cfqq->p_node, cfqq->p_root);
632 * Update cfqq's position in the service tree.
634 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
637 * Resorting requires the cfqq to be on the RR list already.
639 if (cfq_cfqq_on_rr(cfqq)) {
640 cfq_service_tree_add(cfqd, cfqq, 0);
641 cfq_prio_tree_add(cfqd, cfqq);
646 * add to busy list of queues for service, trying to be fair in ordering
647 * the pending list according to last request service
649 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
651 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
652 BUG_ON(cfq_cfqq_on_rr(cfqq));
653 cfq_mark_cfqq_on_rr(cfqq);
656 cfq_resort_rr_list(cfqd, cfqq);
660 * Called when the cfqq no longer has requests pending, remove it from
663 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
665 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
666 BUG_ON(!cfq_cfqq_on_rr(cfqq));
667 cfq_clear_cfqq_on_rr(cfqq);
669 if (!RB_EMPTY_NODE(&cfqq->rb_node))
670 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
672 rb_erase(&cfqq->p_node, cfqq->p_root);
676 BUG_ON(!cfqd->busy_queues);
681 * rb tree support functions
683 static void cfq_del_rq_rb(struct request *rq)
685 struct cfq_queue *cfqq = RQ_CFQQ(rq);
686 struct cfq_data *cfqd = cfqq->cfqd;
687 const int sync = rq_is_sync(rq);
689 BUG_ON(!cfqq->queued[sync]);
690 cfqq->queued[sync]--;
692 elv_rb_del(&cfqq->sort_list, rq);
694 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
695 cfq_del_cfqq_rr(cfqd, cfqq);
698 static void cfq_add_rq_rb(struct request *rq)
700 struct cfq_queue *cfqq = RQ_CFQQ(rq);
701 struct cfq_data *cfqd = cfqq->cfqd;
702 struct request *__alias, *prev;
704 cfqq->queued[rq_is_sync(rq)]++;
707 * looks a little odd, but the first insert might return an alias.
708 * if that happens, put the alias on the dispatch list
710 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
711 cfq_dispatch_insert(cfqd->queue, __alias);
713 if (!cfq_cfqq_on_rr(cfqq))
714 cfq_add_cfqq_rr(cfqd, cfqq);
717 * check if this request is a better next-serve candidate
719 prev = cfqq->next_rq;
720 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
723 * adjust priority tree position, if ->next_rq changes
725 if (prev != cfqq->next_rq)
726 cfq_prio_tree_add(cfqd, cfqq);
728 BUG_ON(!cfqq->next_rq);
731 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
733 elv_rb_del(&cfqq->sort_list, rq);
734 cfqq->queued[rq_is_sync(rq)]--;
738 static struct request *
739 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
741 struct task_struct *tsk = current;
742 struct cfq_io_context *cic;
743 struct cfq_queue *cfqq;
745 cic = cfq_cic_lookup(cfqd, tsk->io_context);
749 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
751 sector_t sector = bio->bi_sector + bio_sectors(bio);
753 return elv_rb_find(&cfqq->sort_list, sector);
759 static void cfq_activate_request(struct request_queue *q, struct request *rq)
761 struct cfq_data *cfqd = q->elevator->elevator_data;
763 cfqd->rq_in_driver[rq_is_sync(rq)]++;
764 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
767 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
770 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
772 struct cfq_data *cfqd = q->elevator->elevator_data;
773 const int sync = rq_is_sync(rq);
775 WARN_ON(!cfqd->rq_in_driver[sync]);
776 cfqd->rq_in_driver[sync]--;
777 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
781 static void cfq_remove_request(struct request *rq)
783 struct cfq_queue *cfqq = RQ_CFQQ(rq);
785 if (cfqq->next_rq == rq)
786 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
788 list_del_init(&rq->queuelist);
791 cfqq->cfqd->rq_queued--;
792 if (rq_is_meta(rq)) {
793 WARN_ON(!cfqq->meta_pending);
794 cfqq->meta_pending--;
798 static int cfq_merge(struct request_queue *q, struct request **req,
801 struct cfq_data *cfqd = q->elevator->elevator_data;
802 struct request *__rq;
804 __rq = cfq_find_rq_fmerge(cfqd, bio);
805 if (__rq && elv_rq_merge_ok(__rq, bio)) {
807 return ELEVATOR_FRONT_MERGE;
810 return ELEVATOR_NO_MERGE;
813 static void cfq_merged_request(struct request_queue *q, struct request *req,
816 if (type == ELEVATOR_FRONT_MERGE) {
817 struct cfq_queue *cfqq = RQ_CFQQ(req);
819 cfq_reposition_rq_rb(cfqq, req);
824 cfq_merged_requests(struct request_queue *q, struct request *rq,
825 struct request *next)
828 * reposition in fifo if next is older than rq
830 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
831 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
832 list_move(&rq->queuelist, &next->queuelist);
833 rq_set_fifo_time(rq, rq_fifo_time(next));
836 cfq_remove_request(next);
839 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
842 struct cfq_data *cfqd = q->elevator->elevator_data;
843 struct cfq_io_context *cic;
844 struct cfq_queue *cfqq;
847 * Disallow merge of a sync bio into an async request.
849 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
853 * Lookup the cfqq that this bio will be queued with. Allow
854 * merge only if rq is queued there.
856 cic = cfq_cic_lookup(cfqd, current->io_context);
860 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
861 if (cfqq == RQ_CFQQ(rq))
867 static void __cfq_set_active_queue(struct cfq_data *cfqd,
868 struct cfq_queue *cfqq)
871 cfq_log_cfqq(cfqd, cfqq, "set_active");
873 cfqq->slice_dispatch = 0;
875 cfq_clear_cfqq_wait_request(cfqq);
876 cfq_clear_cfqq_must_dispatch(cfqq);
877 cfq_clear_cfqq_must_alloc_slice(cfqq);
878 cfq_clear_cfqq_fifo_expire(cfqq);
879 cfq_mark_cfqq_slice_new(cfqq);
881 del_timer(&cfqd->idle_slice_timer);
884 cfqd->active_queue = cfqq;
888 * current cfqq expired its slice (or was too idle), select new one
891 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
894 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
896 if (cfq_cfqq_wait_request(cfqq))
897 del_timer(&cfqd->idle_slice_timer);
899 cfq_clear_cfqq_wait_request(cfqq);
902 * store what was left of this slice, if the queue idled/timed out
904 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
905 cfqq->slice_resid = cfqq->slice_end - jiffies;
906 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
909 cfq_resort_rr_list(cfqd, cfqq);
911 if (cfqq == cfqd->active_queue)
912 cfqd->active_queue = NULL;
914 if (cfqd->active_cic) {
915 put_io_context(cfqd->active_cic->ioc);
916 cfqd->active_cic = NULL;
920 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
922 struct cfq_queue *cfqq = cfqd->active_queue;
925 __cfq_slice_expired(cfqd, cfqq, timed_out);
929 * Get next queue for service. Unless we have a queue preemption,
930 * we'll simply select the first cfqq in the service tree.
932 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
934 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
937 return cfq_rb_first(&cfqd->service_tree);
941 * Get and set a new active queue for service.
943 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
944 struct cfq_queue *cfqq)
947 cfqq = cfq_get_next_queue(cfqd);
949 cfq_clear_cfqq_coop(cfqq);
952 __cfq_set_active_queue(cfqd, cfqq);
956 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
959 if (blk_rq_pos(rq) >= cfqd->last_position)
960 return blk_rq_pos(rq) - cfqd->last_position;
962 return cfqd->last_position - blk_rq_pos(rq);
965 #define CIC_SEEK_THR 8 * 1024
966 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
968 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
970 struct cfq_io_context *cic = cfqd->active_cic;
971 sector_t sdist = cic->seek_mean;
973 if (!sample_valid(cic->seek_samples))
974 sdist = CIC_SEEK_THR;
976 return cfq_dist_from_last(cfqd, rq) <= sdist;
979 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
980 struct cfq_queue *cur_cfqq)
982 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
983 struct rb_node *parent, *node;
984 struct cfq_queue *__cfqq;
985 sector_t sector = cfqd->last_position;
987 if (RB_EMPTY_ROOT(root))
991 * First, if we find a request starting at the end of the last
992 * request, choose it.
994 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
999 * If the exact sector wasn't found, the parent of the NULL leaf
1000 * will contain the closest sector.
1002 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1003 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1006 if (blk_rq_pos(__cfqq->next_rq) < sector)
1007 node = rb_next(&__cfqq->p_node);
1009 node = rb_prev(&__cfqq->p_node);
1013 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1014 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1022 * cur_cfqq - passed in so that we don't decide that the current queue is
1023 * closely cooperating with itself.
1025 * So, basically we're assuming that that cur_cfqq has dispatched at least
1026 * one request, and that cfqd->last_position reflects a position on the disk
1027 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1030 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1031 struct cfq_queue *cur_cfqq,
1034 struct cfq_queue *cfqq;
1037 * A valid cfq_io_context is necessary to compare requests against
1038 * the seek_mean of the current cfqq.
1040 if (!cfqd->active_cic)
1044 * We should notice if some of the queues are cooperating, eg
1045 * working closely on the same area of the disk. In that case,
1046 * we can group them together and don't waste time idling.
1048 cfqq = cfqq_close(cfqd, cur_cfqq);
1052 if (cfq_cfqq_coop(cfqq))
1056 cfq_mark_cfqq_coop(cfqq);
1060 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1062 struct cfq_queue *cfqq = cfqd->active_queue;
1063 struct cfq_io_context *cic;
1067 * SSD device without seek penalty, disable idling. But only do so
1068 * for devices that support queuing, otherwise we still have a problem
1069 * with sync vs async workloads.
1071 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1074 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1075 WARN_ON(cfq_cfqq_slice_new(cfqq));
1078 * idle is disabled, either manually or by past process history
1080 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1084 * still requests with the driver, don't idle
1086 if (rq_in_driver(cfqd))
1090 * task has exited, don't wait
1092 cic = cfqd->active_cic;
1093 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1096 cfq_mark_cfqq_wait_request(cfqq);
1099 * we don't want to idle for seeks, but we do want to allow
1100 * fair distribution of slice time for a process doing back-to-back
1101 * seeks. so allow a little bit of time for him to submit a new rq
1103 sl = cfqd->cfq_slice_idle;
1104 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1105 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1107 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1108 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1112 * Move request from internal lists to the request queue dispatch list.
1114 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1116 struct cfq_data *cfqd = q->elevator->elevator_data;
1117 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1119 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1121 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1122 cfq_remove_request(rq);
1124 elv_dispatch_sort(q, rq);
1126 if (cfq_cfqq_sync(cfqq))
1127 cfqd->sync_flight++;
1131 * return expired entry, or NULL to just start from scratch in rbtree
1133 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1135 struct request *rq = NULL;
1137 if (cfq_cfqq_fifo_expire(cfqq))
1140 cfq_mark_cfqq_fifo_expire(cfqq);
1142 if (list_empty(&cfqq->fifo))
1145 rq = rq_entry_fifo(cfqq->fifo.next);
1146 if (time_before(jiffies, rq_fifo_time(rq)))
1149 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1154 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1156 const int base_rq = cfqd->cfq_slice_async_rq;
1158 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1160 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1164 * Select a queue for service. If we have a current active queue,
1165 * check whether to continue servicing it, or retrieve and set a new one.
1167 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1169 struct cfq_queue *cfqq, *new_cfqq = NULL;
1171 cfqq = cfqd->active_queue;
1176 * The active queue has run out of time, expire it and select new.
1178 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1182 * The active queue has requests and isn't expired, allow it to
1185 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1189 * If another queue has a request waiting within our mean seek
1190 * distance, let it run. The expire code will check for close
1191 * cooperators and put the close queue at the front of the service
1194 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1199 * No requests pending. If the active queue still has requests in
1200 * flight or is idling for a new request, allow either of these
1201 * conditions to happen (or time out) before selecting a new queue.
1203 if (timer_pending(&cfqd->idle_slice_timer) ||
1204 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1210 cfq_slice_expired(cfqd, 0);
1212 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1217 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1221 while (cfqq->next_rq) {
1222 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1226 BUG_ON(!list_empty(&cfqq->fifo));
1231 * Drain our current requests. Used for barriers and when switching
1232 * io schedulers on-the-fly.
1234 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1236 struct cfq_queue *cfqq;
1239 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1240 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1242 cfq_slice_expired(cfqd, 0);
1244 BUG_ON(cfqd->busy_queues);
1246 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1250 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1252 unsigned int max_dispatch;
1255 * Drain async requests before we start sync IO
1257 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1261 * If this is an async queue and we have sync IO in flight, let it wait
1263 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1266 max_dispatch = cfqd->cfq_quantum;
1267 if (cfq_class_idle(cfqq))
1271 * Does this cfqq already have too much IO in flight?
1273 if (cfqq->dispatched >= max_dispatch) {
1275 * idle queue must always only have a single IO in flight
1277 if (cfq_class_idle(cfqq))
1281 * We have other queues, don't allow more IO from this one
1283 if (cfqd->busy_queues > 1)
1287 * Sole queue user, allow bigger slice
1293 * Async queues must wait a bit before being allowed dispatch.
1294 * We also ramp up the dispatch depth gradually for async IO,
1295 * based on the last sync IO we serviced
1297 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
1298 unsigned long last_sync = jiffies - cfqd->last_end_sync_rq;
1301 depth = last_sync / cfqd->cfq_slice[1];
1302 if (!depth && !cfqq->dispatched)
1304 if (depth < max_dispatch)
1305 max_dispatch = depth;
1309 * If we're below the current max, allow a dispatch
1311 return cfqq->dispatched < max_dispatch;
1315 * Dispatch a request from cfqq, moving them to the request queue
1318 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1322 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1324 if (!cfq_may_dispatch(cfqd, cfqq))
1328 * follow expired path, else get first next available
1330 rq = cfq_check_fifo(cfqq);
1335 * insert request into driver dispatch list
1337 cfq_dispatch_insert(cfqd->queue, rq);
1339 if (!cfqd->active_cic) {
1340 struct cfq_io_context *cic = RQ_CIC(rq);
1342 atomic_long_inc(&cic->ioc->refcount);
1343 cfqd->active_cic = cic;
1350 * Find the cfqq that we need to service and move a request from that to the
1353 static int cfq_dispatch_requests(struct request_queue *q, int force)
1355 struct cfq_data *cfqd = q->elevator->elevator_data;
1356 struct cfq_queue *cfqq;
1358 if (!cfqd->busy_queues)
1361 if (unlikely(force))
1362 return cfq_forced_dispatch(cfqd);
1364 cfqq = cfq_select_queue(cfqd);
1369 * Dispatch a request from this cfqq, if it is allowed
1371 if (!cfq_dispatch_request(cfqd, cfqq))
1374 cfqq->slice_dispatch++;
1375 cfq_clear_cfqq_must_dispatch(cfqq);
1378 * expire an async queue immediately if it has used up its slice. idle
1379 * queue always expire after 1 dispatch round.
1381 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1382 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1383 cfq_class_idle(cfqq))) {
1384 cfqq->slice_end = jiffies + 1;
1385 cfq_slice_expired(cfqd, 0);
1388 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
1393 * task holds one reference to the queue, dropped when task exits. each rq
1394 * in-flight on this queue also holds a reference, dropped when rq is freed.
1396 * queue lock must be held here.
1398 static void cfq_put_queue(struct cfq_queue *cfqq)
1400 struct cfq_data *cfqd = cfqq->cfqd;
1402 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1404 if (!atomic_dec_and_test(&cfqq->ref))
1407 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1408 BUG_ON(rb_first(&cfqq->sort_list));
1409 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1410 BUG_ON(cfq_cfqq_on_rr(cfqq));
1412 if (unlikely(cfqd->active_queue == cfqq)) {
1413 __cfq_slice_expired(cfqd, cfqq, 0);
1414 cfq_schedule_dispatch(cfqd);
1417 kmem_cache_free(cfq_pool, cfqq);
1421 * Must always be called with the rcu_read_lock() held
1424 __call_for_each_cic(struct io_context *ioc,
1425 void (*func)(struct io_context *, struct cfq_io_context *))
1427 struct cfq_io_context *cic;
1428 struct hlist_node *n;
1430 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1435 * Call func for each cic attached to this ioc.
1438 call_for_each_cic(struct io_context *ioc,
1439 void (*func)(struct io_context *, struct cfq_io_context *))
1442 __call_for_each_cic(ioc, func);
1446 static void cfq_cic_free_rcu(struct rcu_head *head)
1448 struct cfq_io_context *cic;
1450 cic = container_of(head, struct cfq_io_context, rcu_head);
1452 kmem_cache_free(cfq_ioc_pool, cic);
1453 elv_ioc_count_dec(cfq_ioc_count);
1457 * CFQ scheduler is exiting, grab exit lock and check
1458 * the pending io context count. If it hits zero,
1459 * complete ioc_gone and set it back to NULL
1461 spin_lock(&ioc_gone_lock);
1462 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
1466 spin_unlock(&ioc_gone_lock);
1470 static void cfq_cic_free(struct cfq_io_context *cic)
1472 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1475 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1477 unsigned long flags;
1479 BUG_ON(!cic->dead_key);
1481 spin_lock_irqsave(&ioc->lock, flags);
1482 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1483 hlist_del_rcu(&cic->cic_list);
1484 spin_unlock_irqrestore(&ioc->lock, flags);
1490 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1491 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1492 * and ->trim() which is called with the task lock held
1494 static void cfq_free_io_context(struct io_context *ioc)
1497 * ioc->refcount is zero here, or we are called from elv_unregister(),
1498 * so no more cic's are allowed to be linked into this ioc. So it
1499 * should be ok to iterate over the known list, we will see all cic's
1500 * since no new ones are added.
1502 __call_for_each_cic(ioc, cic_free_func);
1505 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1507 if (unlikely(cfqq == cfqd->active_queue)) {
1508 __cfq_slice_expired(cfqd, cfqq, 0);
1509 cfq_schedule_dispatch(cfqd);
1512 cfq_put_queue(cfqq);
1515 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1516 struct cfq_io_context *cic)
1518 struct io_context *ioc = cic->ioc;
1520 list_del_init(&cic->queue_list);
1523 * Make sure key == NULL is seen for dead queues
1526 cic->dead_key = (unsigned long) cic->key;
1529 if (ioc->ioc_data == cic)
1530 rcu_assign_pointer(ioc->ioc_data, NULL);
1532 if (cic->cfqq[BLK_RW_ASYNC]) {
1533 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1534 cic->cfqq[BLK_RW_ASYNC] = NULL;
1537 if (cic->cfqq[BLK_RW_SYNC]) {
1538 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1539 cic->cfqq[BLK_RW_SYNC] = NULL;
1543 static void cfq_exit_single_io_context(struct io_context *ioc,
1544 struct cfq_io_context *cic)
1546 struct cfq_data *cfqd = cic->key;
1549 struct request_queue *q = cfqd->queue;
1550 unsigned long flags;
1552 spin_lock_irqsave(q->queue_lock, flags);
1555 * Ensure we get a fresh copy of the ->key to prevent
1556 * race between exiting task and queue
1558 smp_read_barrier_depends();
1560 __cfq_exit_single_io_context(cfqd, cic);
1562 spin_unlock_irqrestore(q->queue_lock, flags);
1567 * The process that ioc belongs to has exited, we need to clean up
1568 * and put the internal structures we have that belongs to that process.
1570 static void cfq_exit_io_context(struct io_context *ioc)
1572 call_for_each_cic(ioc, cfq_exit_single_io_context);
1575 static struct cfq_io_context *
1576 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1578 struct cfq_io_context *cic;
1580 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1583 cic->last_end_request = jiffies;
1584 INIT_LIST_HEAD(&cic->queue_list);
1585 INIT_HLIST_NODE(&cic->cic_list);
1586 cic->dtor = cfq_free_io_context;
1587 cic->exit = cfq_exit_io_context;
1588 elv_ioc_count_inc(cfq_ioc_count);
1594 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1596 struct task_struct *tsk = current;
1599 if (!cfq_cfqq_prio_changed(cfqq))
1602 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1603 switch (ioprio_class) {
1605 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1606 case IOPRIO_CLASS_NONE:
1608 * no prio set, inherit CPU scheduling settings
1610 cfqq->ioprio = task_nice_ioprio(tsk);
1611 cfqq->ioprio_class = task_nice_ioclass(tsk);
1613 case IOPRIO_CLASS_RT:
1614 cfqq->ioprio = task_ioprio(ioc);
1615 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1617 case IOPRIO_CLASS_BE:
1618 cfqq->ioprio = task_ioprio(ioc);
1619 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1621 case IOPRIO_CLASS_IDLE:
1622 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1624 cfq_clear_cfqq_idle_window(cfqq);
1629 * keep track of original prio settings in case we have to temporarily
1630 * elevate the priority of this queue
1632 cfqq->org_ioprio = cfqq->ioprio;
1633 cfqq->org_ioprio_class = cfqq->ioprio_class;
1634 cfq_clear_cfqq_prio_changed(cfqq);
1637 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1639 struct cfq_data *cfqd = cic->key;
1640 struct cfq_queue *cfqq;
1641 unsigned long flags;
1643 if (unlikely(!cfqd))
1646 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1648 cfqq = cic->cfqq[BLK_RW_ASYNC];
1650 struct cfq_queue *new_cfqq;
1651 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1654 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1655 cfq_put_queue(cfqq);
1659 cfqq = cic->cfqq[BLK_RW_SYNC];
1661 cfq_mark_cfqq_prio_changed(cfqq);
1663 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1666 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1668 call_for_each_cic(ioc, changed_ioprio);
1669 ioc->ioprio_changed = 0;
1672 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1673 pid_t pid, int is_sync)
1675 RB_CLEAR_NODE(&cfqq->rb_node);
1676 RB_CLEAR_NODE(&cfqq->p_node);
1677 INIT_LIST_HEAD(&cfqq->fifo);
1679 atomic_set(&cfqq->ref, 0);
1682 cfq_mark_cfqq_prio_changed(cfqq);
1685 if (!cfq_class_idle(cfqq))
1686 cfq_mark_cfqq_idle_window(cfqq);
1687 cfq_mark_cfqq_sync(cfqq);
1692 static struct cfq_queue *
1693 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1694 struct io_context *ioc, gfp_t gfp_mask)
1696 struct cfq_queue *cfqq, *new_cfqq = NULL;
1697 struct cfq_io_context *cic;
1700 cic = cfq_cic_lookup(cfqd, ioc);
1701 /* cic always exists here */
1702 cfqq = cic_to_cfqq(cic, is_sync);
1705 * Always try a new alloc if we fell back to the OOM cfqq
1706 * originally, since it should just be a temporary situation.
1708 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1713 } else if (gfp_mask & __GFP_WAIT) {
1714 spin_unlock_irq(cfqd->queue->queue_lock);
1715 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1716 gfp_mask | __GFP_ZERO,
1718 spin_lock_irq(cfqd->queue->queue_lock);
1722 cfqq = kmem_cache_alloc_node(cfq_pool,
1723 gfp_mask | __GFP_ZERO,
1728 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1729 cfq_init_prio_data(cfqq, ioc);
1730 cfq_log_cfqq(cfqd, cfqq, "alloced");
1732 cfqq = &cfqd->oom_cfqq;
1736 kmem_cache_free(cfq_pool, new_cfqq);
1741 static struct cfq_queue **
1742 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1744 switch (ioprio_class) {
1745 case IOPRIO_CLASS_RT:
1746 return &cfqd->async_cfqq[0][ioprio];
1747 case IOPRIO_CLASS_BE:
1748 return &cfqd->async_cfqq[1][ioprio];
1749 case IOPRIO_CLASS_IDLE:
1750 return &cfqd->async_idle_cfqq;
1756 static struct cfq_queue *
1757 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1760 const int ioprio = task_ioprio(ioc);
1761 const int ioprio_class = task_ioprio_class(ioc);
1762 struct cfq_queue **async_cfqq = NULL;
1763 struct cfq_queue *cfqq = NULL;
1766 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1771 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1774 * pin the queue now that it's allocated, scheduler exit will prune it
1776 if (!is_sync && !(*async_cfqq)) {
1777 atomic_inc(&cfqq->ref);
1781 atomic_inc(&cfqq->ref);
1786 * We drop cfq io contexts lazily, so we may find a dead one.
1789 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1790 struct cfq_io_context *cic)
1792 unsigned long flags;
1794 WARN_ON(!list_empty(&cic->queue_list));
1796 spin_lock_irqsave(&ioc->lock, flags);
1798 BUG_ON(ioc->ioc_data == cic);
1800 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1801 hlist_del_rcu(&cic->cic_list);
1802 spin_unlock_irqrestore(&ioc->lock, flags);
1807 static struct cfq_io_context *
1808 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1810 struct cfq_io_context *cic;
1811 unsigned long flags;
1820 * we maintain a last-hit cache, to avoid browsing over the tree
1822 cic = rcu_dereference(ioc->ioc_data);
1823 if (cic && cic->key == cfqd) {
1829 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1833 /* ->key must be copied to avoid race with cfq_exit_queue() */
1836 cfq_drop_dead_cic(cfqd, ioc, cic);
1841 spin_lock_irqsave(&ioc->lock, flags);
1842 rcu_assign_pointer(ioc->ioc_data, cic);
1843 spin_unlock_irqrestore(&ioc->lock, flags);
1851 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1852 * the process specific cfq io context when entered from the block layer.
1853 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1855 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1856 struct cfq_io_context *cic, gfp_t gfp_mask)
1858 unsigned long flags;
1861 ret = radix_tree_preload(gfp_mask);
1866 spin_lock_irqsave(&ioc->lock, flags);
1867 ret = radix_tree_insert(&ioc->radix_root,
1868 (unsigned long) cfqd, cic);
1870 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1871 spin_unlock_irqrestore(&ioc->lock, flags);
1873 radix_tree_preload_end();
1876 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1877 list_add(&cic->queue_list, &cfqd->cic_list);
1878 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1883 printk(KERN_ERR "cfq: cic link failed!\n");
1889 * Setup general io context and cfq io context. There can be several cfq
1890 * io contexts per general io context, if this process is doing io to more
1891 * than one device managed by cfq.
1893 static struct cfq_io_context *
1894 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1896 struct io_context *ioc = NULL;
1897 struct cfq_io_context *cic;
1899 might_sleep_if(gfp_mask & __GFP_WAIT);
1901 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1905 cic = cfq_cic_lookup(cfqd, ioc);
1909 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1913 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1917 smp_read_barrier_depends();
1918 if (unlikely(ioc->ioprio_changed))
1919 cfq_ioc_set_ioprio(ioc);
1925 put_io_context(ioc);
1930 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1932 unsigned long elapsed = jiffies - cic->last_end_request;
1933 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1935 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1936 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1937 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1941 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1947 if (!cic->last_request_pos)
1949 else if (cic->last_request_pos < blk_rq_pos(rq))
1950 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1952 sdist = cic->last_request_pos - blk_rq_pos(rq);
1955 * Don't allow the seek distance to get too large from the
1956 * odd fragment, pagein, etc
1958 if (cic->seek_samples <= 60) /* second&third seek */
1959 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1961 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1963 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1964 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1965 total = cic->seek_total + (cic->seek_samples/2);
1966 do_div(total, cic->seek_samples);
1967 cic->seek_mean = (sector_t)total;
1971 * Disable idle window if the process thinks too long or seeks so much that
1975 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1976 struct cfq_io_context *cic)
1978 int old_idle, enable_idle;
1981 * Don't idle for async or idle io prio class
1983 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1986 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1988 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1989 (!cfqd->cfq_latency && cfqd->hw_tag && CIC_SEEKY(cic)))
1991 else if (sample_valid(cic->ttime_samples)) {
1992 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1998 if (old_idle != enable_idle) {
1999 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
2001 cfq_mark_cfqq_idle_window(cfqq);
2003 cfq_clear_cfqq_idle_window(cfqq);
2008 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2009 * no or if we aren't sure, a 1 will cause a preempt.
2012 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
2015 struct cfq_queue *cfqq;
2017 cfqq = cfqd->active_queue;
2021 if (cfq_slice_used(cfqq))
2024 if (cfq_class_idle(new_cfqq))
2027 if (cfq_class_idle(cfqq))
2031 * if the new request is sync, but the currently running queue is
2032 * not, let the sync request have priority.
2034 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2038 * So both queues are sync. Let the new request get disk time if
2039 * it's a metadata request and the current queue is doing regular IO.
2041 if (rq_is_meta(rq) && !cfqq->meta_pending)
2045 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2047 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2050 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2054 * if this request is as-good as one we would expect from the
2055 * current cfqq, let it preempt
2057 if (cfq_rq_close(cfqd, rq))
2064 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2065 * let it have half of its nominal slice.
2067 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2069 cfq_log_cfqq(cfqd, cfqq, "preempt");
2070 cfq_slice_expired(cfqd, 1);
2073 * Put the new queue at the front of the of the current list,
2074 * so we know that it will be selected next.
2076 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2078 cfq_service_tree_add(cfqd, cfqq, 1);
2080 cfqq->slice_end = 0;
2081 cfq_mark_cfqq_slice_new(cfqq);
2085 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2086 * something we should do about it
2089 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2092 struct cfq_io_context *cic = RQ_CIC(rq);
2096 cfqq->meta_pending++;
2098 cfq_update_io_thinktime(cfqd, cic);
2099 cfq_update_io_seektime(cfqd, cic, rq);
2100 cfq_update_idle_window(cfqd, cfqq, cic);
2102 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2104 if (cfqq == cfqd->active_queue) {
2106 * Remember that we saw a request from this process, but
2107 * don't start queuing just yet. Otherwise we risk seeing lots
2108 * of tiny requests, because we disrupt the normal plugging
2109 * and merging. If the request is already larger than a single
2110 * page, let it rip immediately. For that case we assume that
2111 * merging is already done. Ditto for a busy system that
2112 * has other work pending, don't risk delaying until the
2113 * idle timer unplug to continue working.
2115 if (cfq_cfqq_wait_request(cfqq)) {
2116 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2117 cfqd->busy_queues > 1) {
2118 del_timer(&cfqd->idle_slice_timer);
2119 __blk_run_queue(cfqd->queue);
2121 cfq_mark_cfqq_must_dispatch(cfqq);
2123 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2125 * not the active queue - expire current slice if it is
2126 * idle and has expired it's mean thinktime or this new queue
2127 * has some old slice time left and is of higher priority or
2128 * this new queue is RT and the current one is BE
2130 cfq_preempt_queue(cfqd, cfqq);
2131 __blk_run_queue(cfqd->queue);
2135 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2137 struct cfq_data *cfqd = q->elevator->elevator_data;
2138 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2140 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2141 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2145 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
2146 list_add_tail(&rq->queuelist, &cfqq->fifo);
2148 cfq_rq_enqueued(cfqd, cfqq, rq);
2152 * Update hw_tag based on peak queue depth over 50 samples under
2155 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2157 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2158 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
2160 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2161 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2164 if (cfqd->hw_tag_samples++ < 50)
2167 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2172 cfqd->hw_tag_samples = 0;
2173 cfqd->rq_in_driver_peak = 0;
2176 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2178 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2179 struct cfq_data *cfqd = cfqq->cfqd;
2180 const int sync = rq_is_sync(rq);
2184 cfq_log_cfqq(cfqd, cfqq, "complete");
2186 cfq_update_hw_tag(cfqd);
2188 WARN_ON(!cfqd->rq_in_driver[sync]);
2189 WARN_ON(!cfqq->dispatched);
2190 cfqd->rq_in_driver[sync]--;
2193 if (cfq_cfqq_sync(cfqq))
2194 cfqd->sync_flight--;
2197 RQ_CIC(rq)->last_end_request = now;
2198 cfqd->last_end_sync_rq = now;
2202 * If this is the active queue, check if it needs to be expired,
2203 * or if we want to idle in case it has no pending requests.
2205 if (cfqd->active_queue == cfqq) {
2206 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2208 if (cfq_cfqq_slice_new(cfqq)) {
2209 cfq_set_prio_slice(cfqd, cfqq);
2210 cfq_clear_cfqq_slice_new(cfqq);
2213 * If there are no requests waiting in this queue, and
2214 * there are other queues ready to issue requests, AND
2215 * those other queues are issuing requests within our
2216 * mean seek distance, give them a chance to run instead
2219 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2220 cfq_slice_expired(cfqd, 1);
2221 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2222 sync && !rq_noidle(rq))
2223 cfq_arm_slice_timer(cfqd);
2226 if (!rq_in_driver(cfqd))
2227 cfq_schedule_dispatch(cfqd);
2231 * we temporarily boost lower priority queues if they are holding fs exclusive
2232 * resources. they are boosted to normal prio (CLASS_BE/4)
2234 static void cfq_prio_boost(struct cfq_queue *cfqq)
2236 if (has_fs_excl()) {
2238 * boost idle prio on transactions that would lock out other
2239 * users of the filesystem
2241 if (cfq_class_idle(cfqq))
2242 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2243 if (cfqq->ioprio > IOPRIO_NORM)
2244 cfqq->ioprio = IOPRIO_NORM;
2247 * check if we need to unboost the queue
2249 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2250 cfqq->ioprio_class = cfqq->org_ioprio_class;
2251 if (cfqq->ioprio != cfqq->org_ioprio)
2252 cfqq->ioprio = cfqq->org_ioprio;
2256 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2258 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
2259 cfq_mark_cfqq_must_alloc_slice(cfqq);
2260 return ELV_MQUEUE_MUST;
2263 return ELV_MQUEUE_MAY;
2266 static int cfq_may_queue(struct request_queue *q, int rw)
2268 struct cfq_data *cfqd = q->elevator->elevator_data;
2269 struct task_struct *tsk = current;
2270 struct cfq_io_context *cic;
2271 struct cfq_queue *cfqq;
2274 * don't force setup of a queue from here, as a call to may_queue
2275 * does not necessarily imply that a request actually will be queued.
2276 * so just lookup a possibly existing queue, or return 'may queue'
2279 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2281 return ELV_MQUEUE_MAY;
2283 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2285 cfq_init_prio_data(cfqq, cic->ioc);
2286 cfq_prio_boost(cfqq);
2288 return __cfq_may_queue(cfqq);
2291 return ELV_MQUEUE_MAY;
2295 * queue lock held here
2297 static void cfq_put_request(struct request *rq)
2299 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2302 const int rw = rq_data_dir(rq);
2304 BUG_ON(!cfqq->allocated[rw]);
2305 cfqq->allocated[rw]--;
2307 put_io_context(RQ_CIC(rq)->ioc);
2309 rq->elevator_private = NULL;
2310 rq->elevator_private2 = NULL;
2312 cfq_put_queue(cfqq);
2317 * Allocate cfq data structures associated with this request.
2320 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2322 struct cfq_data *cfqd = q->elevator->elevator_data;
2323 struct cfq_io_context *cic;
2324 const int rw = rq_data_dir(rq);
2325 const int is_sync = rq_is_sync(rq);
2326 struct cfq_queue *cfqq;
2327 unsigned long flags;
2329 might_sleep_if(gfp_mask & __GFP_WAIT);
2331 cic = cfq_get_io_context(cfqd, gfp_mask);
2333 spin_lock_irqsave(q->queue_lock, flags);
2338 cfqq = cic_to_cfqq(cic, is_sync);
2339 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2340 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2341 cic_set_cfqq(cic, cfqq, is_sync);
2344 cfqq->allocated[rw]++;
2345 atomic_inc(&cfqq->ref);
2347 spin_unlock_irqrestore(q->queue_lock, flags);
2349 rq->elevator_private = cic;
2350 rq->elevator_private2 = cfqq;
2355 put_io_context(cic->ioc);
2357 cfq_schedule_dispatch(cfqd);
2358 spin_unlock_irqrestore(q->queue_lock, flags);
2359 cfq_log(cfqd, "set_request fail");
2363 static void cfq_kick_queue(struct work_struct *work)
2365 struct cfq_data *cfqd =
2366 container_of(work, struct cfq_data, unplug_work);
2367 struct request_queue *q = cfqd->queue;
2369 spin_lock_irq(q->queue_lock);
2370 __blk_run_queue(cfqd->queue);
2371 spin_unlock_irq(q->queue_lock);
2375 * Timer running if the active_queue is currently idling inside its time slice
2377 static void cfq_idle_slice_timer(unsigned long data)
2379 struct cfq_data *cfqd = (struct cfq_data *) data;
2380 struct cfq_queue *cfqq;
2381 unsigned long flags;
2384 cfq_log(cfqd, "idle timer fired");
2386 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2388 cfqq = cfqd->active_queue;
2393 * We saw a request before the queue expired, let it through
2395 if (cfq_cfqq_must_dispatch(cfqq))
2401 if (cfq_slice_used(cfqq))
2405 * only expire and reinvoke request handler, if there are
2406 * other queues with pending requests
2408 if (!cfqd->busy_queues)
2412 * not expired and it has a request pending, let it dispatch
2414 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2418 cfq_slice_expired(cfqd, timed_out);
2420 cfq_schedule_dispatch(cfqd);
2422 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2425 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2427 del_timer_sync(&cfqd->idle_slice_timer);
2428 cancel_work_sync(&cfqd->unplug_work);
2431 static void cfq_put_async_queues(struct cfq_data *cfqd)
2435 for (i = 0; i < IOPRIO_BE_NR; i++) {
2436 if (cfqd->async_cfqq[0][i])
2437 cfq_put_queue(cfqd->async_cfqq[0][i]);
2438 if (cfqd->async_cfqq[1][i])
2439 cfq_put_queue(cfqd->async_cfqq[1][i]);
2442 if (cfqd->async_idle_cfqq)
2443 cfq_put_queue(cfqd->async_idle_cfqq);
2446 static void cfq_exit_queue(struct elevator_queue *e)
2448 struct cfq_data *cfqd = e->elevator_data;
2449 struct request_queue *q = cfqd->queue;
2451 cfq_shutdown_timer_wq(cfqd);
2453 spin_lock_irq(q->queue_lock);
2455 if (cfqd->active_queue)
2456 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2458 while (!list_empty(&cfqd->cic_list)) {
2459 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2460 struct cfq_io_context,
2463 __cfq_exit_single_io_context(cfqd, cic);
2466 cfq_put_async_queues(cfqd);
2468 spin_unlock_irq(q->queue_lock);
2470 cfq_shutdown_timer_wq(cfqd);
2475 static void *cfq_init_queue(struct request_queue *q)
2477 struct cfq_data *cfqd;
2480 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2484 cfqd->service_tree = CFQ_RB_ROOT;
2487 * Not strictly needed (since RB_ROOT just clears the node and we
2488 * zeroed cfqd on alloc), but better be safe in case someone decides
2489 * to add magic to the rb code
2491 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2492 cfqd->prio_trees[i] = RB_ROOT;
2495 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2496 * Grab a permanent reference to it, so that the normal code flow
2497 * will not attempt to free it.
2499 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2500 atomic_inc(&cfqd->oom_cfqq.ref);
2502 INIT_LIST_HEAD(&cfqd->cic_list);
2506 init_timer(&cfqd->idle_slice_timer);
2507 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2508 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2510 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
2512 cfqd->cfq_quantum = cfq_quantum;
2513 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2514 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2515 cfqd->cfq_back_max = cfq_back_max;
2516 cfqd->cfq_back_penalty = cfq_back_penalty;
2517 cfqd->cfq_slice[0] = cfq_slice_async;
2518 cfqd->cfq_slice[1] = cfq_slice_sync;
2519 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2520 cfqd->cfq_slice_idle = cfq_slice_idle;
2521 cfqd->cfq_latency = 1;
2523 cfqd->last_end_sync_rq = jiffies;
2527 static void cfq_slab_kill(void)
2530 * Caller already ensured that pending RCU callbacks are completed,
2531 * so we should have no busy allocations at this point.
2534 kmem_cache_destroy(cfq_pool);
2536 kmem_cache_destroy(cfq_ioc_pool);
2539 static int __init cfq_slab_setup(void)
2541 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2545 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2556 * sysfs parts below -->
2559 cfq_var_show(unsigned int var, char *page)
2561 return sprintf(page, "%d\n", var);
2565 cfq_var_store(unsigned int *var, const char *page, size_t count)
2567 char *p = (char *) page;
2569 *var = simple_strtoul(p, &p, 10);
2573 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2574 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2576 struct cfq_data *cfqd = e->elevator_data; \
2577 unsigned int __data = __VAR; \
2579 __data = jiffies_to_msecs(__data); \
2580 return cfq_var_show(__data, (page)); \
2582 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2583 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2584 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2585 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2586 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2587 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2588 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2589 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2590 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2591 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
2592 #undef SHOW_FUNCTION
2594 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2595 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2597 struct cfq_data *cfqd = e->elevator_data; \
2598 unsigned int __data; \
2599 int ret = cfq_var_store(&__data, (page), count); \
2600 if (__data < (MIN)) \
2602 else if (__data > (MAX)) \
2605 *(__PTR) = msecs_to_jiffies(__data); \
2607 *(__PTR) = __data; \
2610 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2611 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2613 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2615 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2616 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2618 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2619 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2620 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2621 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2623 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
2624 #undef STORE_FUNCTION
2626 #define CFQ_ATTR(name) \
2627 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2629 static struct elv_fs_entry cfq_attrs[] = {
2631 CFQ_ATTR(fifo_expire_sync),
2632 CFQ_ATTR(fifo_expire_async),
2633 CFQ_ATTR(back_seek_max),
2634 CFQ_ATTR(back_seek_penalty),
2635 CFQ_ATTR(slice_sync),
2636 CFQ_ATTR(slice_async),
2637 CFQ_ATTR(slice_async_rq),
2638 CFQ_ATTR(slice_idle),
2639 CFQ_ATTR(low_latency),
2643 static struct elevator_type iosched_cfq = {
2645 .elevator_merge_fn = cfq_merge,
2646 .elevator_merged_fn = cfq_merged_request,
2647 .elevator_merge_req_fn = cfq_merged_requests,
2648 .elevator_allow_merge_fn = cfq_allow_merge,
2649 .elevator_dispatch_fn = cfq_dispatch_requests,
2650 .elevator_add_req_fn = cfq_insert_request,
2651 .elevator_activate_req_fn = cfq_activate_request,
2652 .elevator_deactivate_req_fn = cfq_deactivate_request,
2653 .elevator_queue_empty_fn = cfq_queue_empty,
2654 .elevator_completed_req_fn = cfq_completed_request,
2655 .elevator_former_req_fn = elv_rb_former_request,
2656 .elevator_latter_req_fn = elv_rb_latter_request,
2657 .elevator_set_req_fn = cfq_set_request,
2658 .elevator_put_req_fn = cfq_put_request,
2659 .elevator_may_queue_fn = cfq_may_queue,
2660 .elevator_init_fn = cfq_init_queue,
2661 .elevator_exit_fn = cfq_exit_queue,
2662 .trim = cfq_free_io_context,
2664 .elevator_attrs = cfq_attrs,
2665 .elevator_name = "cfq",
2666 .elevator_owner = THIS_MODULE,
2669 static int __init cfq_init(void)
2672 * could be 0 on HZ < 1000 setups
2674 if (!cfq_slice_async)
2675 cfq_slice_async = 1;
2676 if (!cfq_slice_idle)
2679 if (cfq_slab_setup())
2682 elv_register(&iosched_cfq);
2687 static void __exit cfq_exit(void)
2689 DECLARE_COMPLETION_ONSTACK(all_gone);
2690 elv_unregister(&iosched_cfq);
2691 ioc_gone = &all_gone;
2692 /* ioc_gone's update must be visible before reading ioc_count */
2696 * this also protects us from entering cfq_slab_kill() with
2697 * pending RCU callbacks
2699 if (elv_ioc_count_read(cfq_ioc_count))
2700 wait_for_completion(&all_gone);
2704 module_init(cfq_init);
2705 module_exit(cfq_exit);
2707 MODULE_AUTHOR("Jens Axboe");
2708 MODULE_LICENSE("GPL");
2709 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");