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@suse.de>
9 #include <linux/kernel.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/bio.h>
14 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/compiler.h>
19 #include <linux/hash.h>
20 #include <linux/rbtree.h>
21 #include <linux/mempool.h>
22 #include <linux/ioprio.h>
23 #include <linux/writeback.h>
28 static const int cfq_quantum = 4; /* max queue in one round of service */
29 static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
30 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
31 static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
32 static const int cfq_back_penalty = 2; /* penalty of a backwards seek */
34 static const int cfq_slice_sync = HZ / 10;
35 static int cfq_slice_async = HZ / 25;
36 static const int cfq_slice_async_rq = 2;
37 static int cfq_slice_idle = HZ / 100;
39 #define CFQ_IDLE_GRACE (HZ / 10)
40 #define CFQ_SLICE_SCALE (5)
42 #define CFQ_KEY_ASYNC (0)
43 #define CFQ_KEY_ANY (0xffff)
46 * disable queueing at the driver/hardware level
48 static const int cfq_max_depth = 2;
50 static DEFINE_RWLOCK(cfq_exit_lock);
53 * for the hash of cfqq inside the cfqd
55 #define CFQ_QHASH_SHIFT 6
56 #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
57 #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
60 * for the hash of crq inside the cfqq
62 #define CFQ_MHASH_SHIFT 6
63 #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
64 #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
65 #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
66 #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
67 #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
69 #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
70 #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
72 #define RQ_DATA(rq) (rq)->elevator_private
78 #define RB_EMPTY(node) ((node)->rb_node == NULL)
79 #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
80 #define RB_CLEAR(node) do { \
81 (node)->rb_parent = NULL; \
82 RB_CLEAR_COLOR((node)); \
83 (node)->rb_right = NULL; \
84 (node)->rb_left = NULL; \
86 #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
87 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
88 #define rq_rb_key(rq) (rq)->sector
90 static kmem_cache_t *crq_pool;
91 static kmem_cache_t *cfq_pool;
92 static kmem_cache_t *cfq_ioc_pool;
94 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
95 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
96 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
97 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
102 #define cfq_cfqq_dispatched(cfqq) \
103 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
105 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
107 #define cfq_cfqq_sync(cfqq) \
108 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
111 * Per block device queue structure
115 request_queue_t *queue;
118 * rr list of queues with requests and the count of them
120 struct list_head rr_list[CFQ_PRIO_LISTS];
121 struct list_head busy_rr;
122 struct list_head cur_rr;
123 struct list_head idle_rr;
124 unsigned int busy_queues;
127 * non-ordered list of empty cfqq's
129 struct list_head empty_list;
134 struct hlist_head *cfq_hash;
137 * global crq hash for all queues
139 struct hlist_head *crq_hash;
141 unsigned int max_queued;
148 * schedule slice state info
151 * idle window management
153 struct timer_list idle_slice_timer;
154 struct work_struct unplug_work;
156 struct cfq_queue *active_queue;
157 struct cfq_io_context *active_cic;
158 int cur_prio, cur_end_prio;
159 unsigned int dispatch_slice;
161 struct timer_list idle_class_timer;
163 sector_t last_sector;
164 unsigned long last_end_request;
166 unsigned int rq_starved;
169 * tunables, see top of file
171 unsigned int cfq_quantum;
172 unsigned int cfq_queued;
173 unsigned int cfq_fifo_expire[2];
174 unsigned int cfq_back_penalty;
175 unsigned int cfq_back_max;
176 unsigned int cfq_slice[2];
177 unsigned int cfq_slice_async_rq;
178 unsigned int cfq_slice_idle;
179 unsigned int cfq_max_depth;
181 struct list_head cic_list;
185 * Per process-grouping structure
188 /* reference count */
190 /* parent cfq_data */
191 struct cfq_data *cfqd;
192 /* cfqq lookup hash */
193 struct hlist_node cfq_hash;
196 /* on either rr or empty list of cfqd */
197 struct list_head cfq_list;
198 /* sorted list of pending requests */
199 struct rb_root sort_list;
200 /* if fifo isn't expired, next request to serve */
201 struct cfq_rq *next_crq;
202 /* requests queued in sort_list */
204 /* currently allocated requests */
206 /* fifo list of requests in sort_list */
207 struct list_head fifo;
209 unsigned long slice_start;
210 unsigned long slice_end;
211 unsigned long slice_left;
212 unsigned long service_last;
214 /* number of requests that are on the dispatch list */
217 /* io prio of this group */
218 unsigned short ioprio, org_ioprio;
219 unsigned short ioprio_class, org_ioprio_class;
221 /* various state flags, see below */
226 struct rb_node rb_node;
228 struct request *request;
229 struct hlist_node hash;
231 struct cfq_queue *cfq_queue;
232 struct cfq_io_context *io_context;
234 unsigned int crq_flags;
237 enum cfqq_state_flags {
238 CFQ_CFQQ_FLAG_on_rr = 0,
239 CFQ_CFQQ_FLAG_wait_request,
240 CFQ_CFQQ_FLAG_must_alloc,
241 CFQ_CFQQ_FLAG_must_alloc_slice,
242 CFQ_CFQQ_FLAG_must_dispatch,
243 CFQ_CFQQ_FLAG_fifo_expire,
244 CFQ_CFQQ_FLAG_idle_window,
245 CFQ_CFQQ_FLAG_prio_changed,
248 #define CFQ_CFQQ_FNS(name) \
249 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
251 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
253 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
255 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
257 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
259 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
263 CFQ_CFQQ_FNS(wait_request);
264 CFQ_CFQQ_FNS(must_alloc);
265 CFQ_CFQQ_FNS(must_alloc_slice);
266 CFQ_CFQQ_FNS(must_dispatch);
267 CFQ_CFQQ_FNS(fifo_expire);
268 CFQ_CFQQ_FNS(idle_window);
269 CFQ_CFQQ_FNS(prio_changed);
272 enum cfq_rq_state_flags {
273 CFQ_CRQ_FLAG_is_sync = 0,
276 #define CFQ_CRQ_FNS(name) \
277 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
279 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
281 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
283 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
285 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
287 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
290 CFQ_CRQ_FNS(is_sync);
293 static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
294 static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
295 static void cfq_put_cfqd(struct cfq_data *cfqd);
297 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
300 * lots of deadline iosched dupes, can be abstracted later...
302 static inline void cfq_del_crq_hash(struct cfq_rq *crq)
304 hlist_del_init(&crq->hash);
307 static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
309 const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
311 hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
314 static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
316 struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
317 struct hlist_node *entry, *next;
319 hlist_for_each_safe(entry, next, hash_list) {
320 struct cfq_rq *crq = list_entry_hash(entry);
321 struct request *__rq = crq->request;
323 if (!rq_mergeable(__rq)) {
324 cfq_del_crq_hash(crq);
328 if (rq_hash_key(__rq) == offset)
336 * scheduler run of queue, if there are requests pending and no one in the
337 * driver that will restart queueing
339 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
341 if (cfqd->busy_queues)
342 kblockd_schedule_work(&cfqd->unplug_work);
345 static int cfq_queue_empty(request_queue_t *q)
347 struct cfq_data *cfqd = q->elevator->elevator_data;
349 return !cfqd->busy_queues;
353 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
354 * We choose the request that is closest to the head right now. Distance
355 * behind the head are penalized and only allowed to a certain extent.
357 static struct cfq_rq *
358 cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
360 sector_t last, s1, s2, d1 = 0, d2 = 0;
361 int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
362 unsigned long back_max;
364 if (crq1 == NULL || crq1 == crq2)
369 if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
371 else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
374 s1 = crq1->request->sector;
375 s2 = crq2->request->sector;
377 last = cfqd->last_sector;
380 * by definition, 1KiB is 2 sectors
382 back_max = cfqd->cfq_back_max * 2;
385 * Strict one way elevator _except_ in the case where we allow
386 * short backward seeks which are biased as twice the cost of a
387 * similar forward seek.
391 else if (s1 + back_max >= last)
392 d1 = (last - s1) * cfqd->cfq_back_penalty;
398 else if (s2 + back_max >= last)
399 d2 = (last - s2) * cfqd->cfq_back_penalty;
403 /* Found required data */
404 if (!r1_wrap && r2_wrap)
406 else if (!r2_wrap && r1_wrap)
408 else if (r1_wrap && r2_wrap) {
409 /* both behind the head */
416 /* Both requests in front of the head */
430 * would be nice to take fifo expire time into account as well
432 static struct cfq_rq *
433 cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
436 struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
437 struct rb_node *rbnext, *rbprev;
439 if (!(rbnext = rb_next(&last->rb_node))) {
440 rbnext = rb_first(&cfqq->sort_list);
441 if (rbnext == &last->rb_node)
445 rbprev = rb_prev(&last->rb_node);
448 crq_prev = rb_entry_crq(rbprev);
450 crq_next = rb_entry_crq(rbnext);
452 return cfq_choose_req(cfqd, crq_next, crq_prev);
455 static void cfq_update_next_crq(struct cfq_rq *crq)
457 struct cfq_queue *cfqq = crq->cfq_queue;
459 if (cfqq->next_crq == crq)
460 cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
463 static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
465 struct cfq_data *cfqd = cfqq->cfqd;
466 struct list_head *list, *entry;
468 BUG_ON(!cfq_cfqq_on_rr(cfqq));
470 list_del(&cfqq->cfq_list);
472 if (cfq_class_rt(cfqq))
473 list = &cfqd->cur_rr;
474 else if (cfq_class_idle(cfqq))
475 list = &cfqd->idle_rr;
478 * if cfqq has requests in flight, don't allow it to be
479 * found in cfq_set_active_queue before it has finished them.
480 * this is done to increase fairness between a process that
481 * has lots of io pending vs one that only generates one
482 * sporadically or synchronously
484 if (cfq_cfqq_dispatched(cfqq))
485 list = &cfqd->busy_rr;
487 list = &cfqd->rr_list[cfqq->ioprio];
491 * if queue was preempted, just add to front to be fair. busy_rr
494 if (preempted || list == &cfqd->busy_rr) {
495 list_add(&cfqq->cfq_list, list);
500 * sort by when queue was last serviced
503 while ((entry = entry->prev) != list) {
504 struct cfq_queue *__cfqq = list_entry_cfqq(entry);
506 if (!__cfqq->service_last)
508 if (time_before(__cfqq->service_last, cfqq->service_last))
512 list_add(&cfqq->cfq_list, entry);
516 * add to busy list of queues for service, trying to be fair in ordering
517 * the pending list according to last request service
520 cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
522 BUG_ON(cfq_cfqq_on_rr(cfqq));
523 cfq_mark_cfqq_on_rr(cfqq);
526 cfq_resort_rr_list(cfqq, 0);
530 cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
532 BUG_ON(!cfq_cfqq_on_rr(cfqq));
533 cfq_clear_cfqq_on_rr(cfqq);
534 list_move(&cfqq->cfq_list, &cfqd->empty_list);
536 BUG_ON(!cfqd->busy_queues);
541 * rb tree support functions
543 static inline void cfq_del_crq_rb(struct cfq_rq *crq)
545 struct cfq_queue *cfqq = crq->cfq_queue;
546 struct cfq_data *cfqd = cfqq->cfqd;
547 const int sync = cfq_crq_is_sync(crq);
549 BUG_ON(!cfqq->queued[sync]);
550 cfqq->queued[sync]--;
552 cfq_update_next_crq(crq);
554 rb_erase(&crq->rb_node, &cfqq->sort_list);
555 RB_CLEAR_COLOR(&crq->rb_node);
557 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
558 cfq_del_cfqq_rr(cfqd, cfqq);
561 static struct cfq_rq *
562 __cfq_add_crq_rb(struct cfq_rq *crq)
564 struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
565 struct rb_node *parent = NULL;
566 struct cfq_rq *__crq;
570 __crq = rb_entry_crq(parent);
572 if (crq->rb_key < __crq->rb_key)
574 else if (crq->rb_key > __crq->rb_key)
580 rb_link_node(&crq->rb_node, parent, p);
584 static void cfq_add_crq_rb(struct cfq_rq *crq)
586 struct cfq_queue *cfqq = crq->cfq_queue;
587 struct cfq_data *cfqd = cfqq->cfqd;
588 struct request *rq = crq->request;
589 struct cfq_rq *__alias;
591 crq->rb_key = rq_rb_key(rq);
592 cfqq->queued[cfq_crq_is_sync(crq)]++;
595 * looks a little odd, but the first insert might return an alias.
596 * if that happens, put the alias on the dispatch list
598 while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
599 cfq_dispatch_insert(cfqd->queue, __alias);
601 rb_insert_color(&crq->rb_node, &cfqq->sort_list);
603 if (!cfq_cfqq_on_rr(cfqq))
604 cfq_add_cfqq_rr(cfqd, cfqq);
607 * check if this request is a better next-serve candidate
609 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
613 cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
615 rb_erase(&crq->rb_node, &cfqq->sort_list);
616 cfqq->queued[cfq_crq_is_sync(crq)]--;
621 static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
624 struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
630 n = cfqq->sort_list.rb_node;
632 struct cfq_rq *crq = rb_entry_crq(n);
634 if (sector < crq->rb_key)
636 else if (sector > crq->rb_key)
646 static void cfq_activate_request(request_queue_t *q, struct request *rq)
648 struct cfq_data *cfqd = q->elevator->elevator_data;
650 cfqd->rq_in_driver++;
653 static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
655 struct cfq_data *cfqd = q->elevator->elevator_data;
657 WARN_ON(!cfqd->rq_in_driver);
658 cfqd->rq_in_driver--;
661 static void cfq_remove_request(struct request *rq)
663 struct cfq_rq *crq = RQ_DATA(rq);
665 list_del_init(&rq->queuelist);
667 cfq_del_crq_hash(crq);
671 cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
673 struct cfq_data *cfqd = q->elevator->elevator_data;
674 struct request *__rq;
677 __rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
678 if (__rq && elv_rq_merge_ok(__rq, bio)) {
679 ret = ELEVATOR_BACK_MERGE;
683 __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
684 if (__rq && elv_rq_merge_ok(__rq, bio)) {
685 ret = ELEVATOR_FRONT_MERGE;
689 return ELEVATOR_NO_MERGE;
695 static void cfq_merged_request(request_queue_t *q, struct request *req)
697 struct cfq_data *cfqd = q->elevator->elevator_data;
698 struct cfq_rq *crq = RQ_DATA(req);
700 cfq_del_crq_hash(crq);
701 cfq_add_crq_hash(cfqd, crq);
703 if (rq_rb_key(req) != crq->rb_key) {
704 struct cfq_queue *cfqq = crq->cfq_queue;
706 cfq_update_next_crq(crq);
707 cfq_reposition_crq_rb(cfqq, crq);
712 cfq_merged_requests(request_queue_t *q, struct request *rq,
713 struct request *next)
715 cfq_merged_request(q, rq);
718 * reposition in fifo if next is older than rq
720 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
721 time_before(next->start_time, rq->start_time))
722 list_move(&rq->queuelist, &next->queuelist);
724 cfq_remove_request(next);
728 __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
732 * stop potential idle class queues waiting service
734 del_timer(&cfqd->idle_class_timer);
736 cfqq->slice_start = jiffies;
738 cfqq->slice_left = 0;
739 cfq_clear_cfqq_must_alloc_slice(cfqq);
740 cfq_clear_cfqq_fifo_expire(cfqq);
743 cfqd->active_queue = cfqq;
747 * current cfqq expired its slice (or was too idle), select new one
750 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
753 unsigned long now = jiffies;
755 if (cfq_cfqq_wait_request(cfqq))
756 del_timer(&cfqd->idle_slice_timer);
758 if (!preempted && !cfq_cfqq_dispatched(cfqq)) {
759 cfqq->service_last = now;
760 cfq_schedule_dispatch(cfqd);
763 cfq_clear_cfqq_must_dispatch(cfqq);
764 cfq_clear_cfqq_wait_request(cfqq);
767 * store what was left of this slice, if the queue idled out
770 if (time_after(cfqq->slice_end, now))
771 cfqq->slice_left = cfqq->slice_end - now;
773 cfqq->slice_left = 0;
775 if (cfq_cfqq_on_rr(cfqq))
776 cfq_resort_rr_list(cfqq, preempted);
778 if (cfqq == cfqd->active_queue)
779 cfqd->active_queue = NULL;
781 if (cfqd->active_cic) {
782 put_io_context(cfqd->active_cic->ioc);
783 cfqd->active_cic = NULL;
786 cfqd->dispatch_slice = 0;
789 static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
791 struct cfq_queue *cfqq = cfqd->active_queue;
794 __cfq_slice_expired(cfqd, cfqq, preempted);
807 static int cfq_get_next_prio_level(struct cfq_data *cfqd)
816 for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) {
817 if (!list_empty(&cfqd->rr_list[p])) {
826 if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
827 cfqd->cur_end_prio = 0;
834 if (unlikely(prio == -1))
837 BUG_ON(prio >= CFQ_PRIO_LISTS);
839 list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr);
841 cfqd->cur_prio = prio + 1;
842 if (cfqd->cur_prio > cfqd->cur_end_prio) {
843 cfqd->cur_end_prio = cfqd->cur_prio;
846 if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
848 cfqd->cur_end_prio = 0;
854 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
856 struct cfq_queue *cfqq = NULL;
859 * if current list is non-empty, grab first entry. if it is empty,
860 * get next prio level and grab first entry then if any are spliced
862 if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
863 cfqq = list_entry_cfqq(cfqd->cur_rr.next);
866 * if we have idle queues and no rt or be queues had pending
867 * requests, either allow immediate service if the grace period
868 * has passed or arm the idle grace timer
870 if (!cfqq && !list_empty(&cfqd->idle_rr)) {
871 unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
873 if (time_after_eq(jiffies, end))
874 cfqq = list_entry_cfqq(cfqd->idle_rr.next);
876 mod_timer(&cfqd->idle_class_timer, end);
879 __cfq_set_active_queue(cfqd, cfqq);
883 static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
888 WARN_ON(!RB_EMPTY(&cfqq->sort_list));
889 WARN_ON(cfqq != cfqd->active_queue);
892 * idle is disabled, either manually or by past process history
894 if (!cfqd->cfq_slice_idle)
896 if (!cfq_cfqq_idle_window(cfqq))
899 * task has exited, don't wait
901 if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
904 cfq_mark_cfqq_must_dispatch(cfqq);
905 cfq_mark_cfqq_wait_request(cfqq);
907 sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
908 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
912 static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
914 struct cfq_data *cfqd = q->elevator->elevator_data;
915 struct cfq_queue *cfqq = crq->cfq_queue;
917 cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
918 cfq_remove_request(crq->request);
919 cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
920 elv_dispatch_sort(q, crq->request);
924 * return expired entry, or NULL to just start from scratch in rbtree
926 static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
928 struct cfq_data *cfqd = cfqq->cfqd;
932 if (cfq_cfqq_fifo_expire(cfqq))
935 if (!list_empty(&cfqq->fifo)) {
936 int fifo = cfq_cfqq_class_sync(cfqq);
938 crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next));
940 if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
941 cfq_mark_cfqq_fifo_expire(cfqq);
950 * Scale schedule slice based on io priority. Use the sync time slice only
951 * if a queue is marked sync and has sync io queued. A sync queue with async
952 * io only, should not get full sync slice length.
955 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
957 const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)];
959 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
961 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio));
965 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
967 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
971 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
973 const int base_rq = cfqd->cfq_slice_async_rq;
975 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
977 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
981 * get next queue for service
983 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
985 unsigned long now = jiffies;
986 struct cfq_queue *cfqq;
988 cfqq = cfqd->active_queue;
995 if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end))
999 * if queue has requests, dispatch one. if not, check if
1000 * enough slice is left to wait for one
1002 if (!RB_EMPTY(&cfqq->sort_list))
1004 else if (cfq_cfqq_class_sync(cfqq) &&
1005 time_before(now, cfqq->slice_end)) {
1006 if (cfq_arm_slice_timer(cfqd, cfqq))
1011 cfq_slice_expired(cfqd, 0);
1013 cfqq = cfq_set_active_queue(cfqd);
1019 __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1024 BUG_ON(RB_EMPTY(&cfqq->sort_list));
1030 * follow expired path, else get first next available
1032 if ((crq = cfq_check_fifo(cfqq)) == NULL)
1033 crq = cfqq->next_crq;
1036 * finally, insert request into driver dispatch list
1038 cfq_dispatch_insert(cfqd->queue, crq);
1040 cfqd->dispatch_slice++;
1043 if (!cfqd->active_cic) {
1044 atomic_inc(&crq->io_context->ioc->refcount);
1045 cfqd->active_cic = crq->io_context;
1048 if (RB_EMPTY(&cfqq->sort_list))
1051 } while (dispatched < max_dispatch);
1054 * if slice end isn't set yet, set it. if at least one request was
1055 * sync, use the sync time slice value
1057 if (!cfqq->slice_end)
1058 cfq_set_prio_slice(cfqd, cfqq);
1061 * expire an async queue immediately if it has used up its slice. idle
1062 * queue always expire after 1 dispatch round.
1064 if ((!cfq_cfqq_sync(cfqq) &&
1065 cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1066 cfq_class_idle(cfqq))
1067 cfq_slice_expired(cfqd, 0);
1073 cfq_forced_dispatch_cfqqs(struct list_head *list)
1076 struct cfq_queue *cfqq, *next;
1079 list_for_each_entry_safe(cfqq, next, list, cfq_list) {
1080 while ((crq = cfqq->next_crq)) {
1081 cfq_dispatch_insert(cfqq->cfqd->queue, crq);
1084 BUG_ON(!list_empty(&cfqq->fifo));
1090 cfq_forced_dispatch(struct cfq_data *cfqd)
1092 int i, dispatched = 0;
1094 for (i = 0; i < CFQ_PRIO_LISTS; i++)
1095 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
1097 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
1098 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
1099 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
1101 cfq_slice_expired(cfqd, 0);
1103 BUG_ON(cfqd->busy_queues);
1109 cfq_dispatch_requests(request_queue_t *q, int force)
1111 struct cfq_data *cfqd = q->elevator->elevator_data;
1112 struct cfq_queue *cfqq;
1114 if (!cfqd->busy_queues)
1117 if (unlikely(force))
1118 return cfq_forced_dispatch(cfqd);
1120 cfqq = cfq_select_queue(cfqd);
1125 * if idle window is disabled, allow queue buildup
1127 if (!cfq_cfqq_idle_window(cfqq) &&
1128 cfqd->rq_in_driver >= cfqd->cfq_max_depth)
1131 cfq_clear_cfqq_must_dispatch(cfqq);
1132 cfq_clear_cfqq_wait_request(cfqq);
1133 del_timer(&cfqd->idle_slice_timer);
1135 max_dispatch = cfqd->cfq_quantum;
1136 if (cfq_class_idle(cfqq))
1139 return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
1146 * task holds one reference to the queue, dropped when task exits. each crq
1147 * in-flight on this queue also holds a reference, dropped when crq is freed.
1149 * queue lock must be held here.
1151 static void cfq_put_queue(struct cfq_queue *cfqq)
1153 struct cfq_data *cfqd = cfqq->cfqd;
1155 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1157 if (!atomic_dec_and_test(&cfqq->ref))
1160 BUG_ON(rb_first(&cfqq->sort_list));
1161 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1162 BUG_ON(cfq_cfqq_on_rr(cfqq));
1164 if (unlikely(cfqd->active_queue == cfqq))
1165 __cfq_slice_expired(cfqd, cfqq, 0);
1167 cfq_put_cfqd(cfqq->cfqd);
1170 * it's on the empty list and still hashed
1172 list_del(&cfqq->cfq_list);
1173 hlist_del(&cfqq->cfq_hash);
1174 kmem_cache_free(cfq_pool, cfqq);
1177 static inline struct cfq_queue *
1178 __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
1181 struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
1182 struct hlist_node *entry, *next;
1184 hlist_for_each_safe(entry, next, hash_list) {
1185 struct cfq_queue *__cfqq = list_entry_qhash(entry);
1186 const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio);
1188 if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
1195 static struct cfq_queue *
1196 cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
1198 return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
1201 static void cfq_free_io_context(struct cfq_io_context *cic)
1203 struct cfq_io_context *__cic;
1204 struct list_head *entry, *next;
1206 list_for_each_safe(entry, next, &cic->list) {
1207 __cic = list_entry(entry, struct cfq_io_context, list);
1208 kmem_cache_free(cfq_ioc_pool, __cic);
1211 kmem_cache_free(cfq_ioc_pool, cic);
1214 static void cfq_trim(struct io_context *ioc)
1216 ioc->set_ioprio = NULL;
1218 cfq_free_io_context(ioc->cic);
1222 * Called with interrupts disabled
1224 static void cfq_exit_single_io_context(struct cfq_io_context *cic)
1226 struct cfq_data *cfqd = cic->key;
1234 WARN_ON(!irqs_disabled());
1236 spin_lock(q->queue_lock);
1238 if (cic->cfqq[ASYNC]) {
1239 if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue))
1240 __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0);
1241 cfq_put_queue(cic->cfqq[ASYNC]);
1242 cic->cfqq[ASYNC] = NULL;
1245 if (cic->cfqq[SYNC]) {
1246 if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue))
1247 __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0);
1248 cfq_put_queue(cic->cfqq[SYNC]);
1249 cic->cfqq[SYNC] = NULL;
1253 list_del_init(&cic->queue_list);
1254 spin_unlock(q->queue_lock);
1258 * Another task may update the task cic list, if it is doing a queue lookup
1259 * on its behalf. cfq_cic_lock excludes such concurrent updates
1261 static void cfq_exit_io_context(struct cfq_io_context *cic)
1263 struct cfq_io_context *__cic;
1264 struct list_head *entry;
1265 unsigned long flags;
1267 local_irq_save(flags);
1270 * put the reference this task is holding to the various queues
1272 read_lock(&cfq_exit_lock);
1273 list_for_each(entry, &cic->list) {
1274 __cic = list_entry(entry, struct cfq_io_context, list);
1275 cfq_exit_single_io_context(__cic);
1278 cfq_exit_single_io_context(cic);
1279 read_unlock(&cfq_exit_lock);
1280 local_irq_restore(flags);
1283 static struct cfq_io_context *
1284 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1286 struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
1289 INIT_LIST_HEAD(&cic->list);
1290 cic->cfqq[ASYNC] = NULL;
1291 cic->cfqq[SYNC] = NULL;
1293 cic->last_end_request = jiffies;
1294 cic->ttime_total = 0;
1295 cic->ttime_samples = 0;
1296 cic->ttime_mean = 0;
1297 cic->dtor = cfq_free_io_context;
1298 cic->exit = cfq_exit_io_context;
1299 INIT_LIST_HEAD(&cic->queue_list);
1305 static void cfq_init_prio_data(struct cfq_queue *cfqq)
1307 struct task_struct *tsk = current;
1310 if (!cfq_cfqq_prio_changed(cfqq))
1313 ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
1314 switch (ioprio_class) {
1316 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1317 case IOPRIO_CLASS_NONE:
1319 * no prio set, place us in the middle of the BE classes
1321 cfqq->ioprio = task_nice_ioprio(tsk);
1322 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1324 case IOPRIO_CLASS_RT:
1325 cfqq->ioprio = task_ioprio(tsk);
1326 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1328 case IOPRIO_CLASS_BE:
1329 cfqq->ioprio = task_ioprio(tsk);
1330 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1332 case IOPRIO_CLASS_IDLE:
1333 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1335 cfq_clear_cfqq_idle_window(cfqq);
1340 * keep track of original prio settings in case we have to temporarily
1341 * elevate the priority of this queue
1343 cfqq->org_ioprio = cfqq->ioprio;
1344 cfqq->org_ioprio_class = cfqq->ioprio_class;
1346 if (cfq_cfqq_on_rr(cfqq))
1347 cfq_resort_rr_list(cfqq, 0);
1349 cfq_clear_cfqq_prio_changed(cfqq);
1352 static inline void changed_ioprio(struct cfq_io_context *cic)
1354 struct cfq_data *cfqd = cic->key;
1355 struct cfq_queue *cfqq;
1357 spin_lock(cfqd->queue->queue_lock);
1358 cfqq = cic->cfqq[ASYNC];
1360 cfq_mark_cfqq_prio_changed(cfqq);
1361 cfq_init_prio_data(cfqq);
1363 cfqq = cic->cfqq[SYNC];
1365 cfq_mark_cfqq_prio_changed(cfqq);
1366 cfq_init_prio_data(cfqq);
1368 spin_unlock(cfqd->queue->queue_lock);
1373 * callback from sys_ioprio_set, irqs are disabled
1375 static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
1377 struct cfq_io_context *cic;
1379 write_lock(&cfq_exit_lock);
1383 changed_ioprio(cic);
1385 list_for_each_entry(cic, &cic->list, list)
1386 changed_ioprio(cic);
1388 write_unlock(&cfq_exit_lock);
1393 static struct cfq_queue *
1394 cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
1397 const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
1398 struct cfq_queue *cfqq, *new_cfqq = NULL;
1401 cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
1407 } else if (gfp_mask & __GFP_WAIT) {
1408 spin_unlock_irq(cfqd->queue->queue_lock);
1409 new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1410 spin_lock_irq(cfqd->queue->queue_lock);
1413 cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1418 memset(cfqq, 0, sizeof(*cfqq));
1420 INIT_HLIST_NODE(&cfqq->cfq_hash);
1421 INIT_LIST_HEAD(&cfqq->cfq_list);
1422 RB_CLEAR_ROOT(&cfqq->sort_list);
1423 INIT_LIST_HEAD(&cfqq->fifo);
1426 hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
1427 atomic_set(&cfqq->ref, 0);
1429 atomic_inc(&cfqd->ref);
1430 cfqq->service_last = 0;
1432 * set ->slice_left to allow preemption for a new process
1434 cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
1435 cfq_mark_cfqq_idle_window(cfqq);
1436 cfq_mark_cfqq_prio_changed(cfqq);
1437 cfq_init_prio_data(cfqq);
1441 kmem_cache_free(cfq_pool, new_cfqq);
1443 atomic_inc(&cfqq->ref);
1445 WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
1450 * Setup general io context and cfq io context. There can be several cfq
1451 * io contexts per general io context, if this process is doing io to more
1452 * than one device managed by cfq. Note that caller is holding a reference to
1453 * cfqq, so we don't need to worry about it disappearing
1455 static struct cfq_io_context *
1456 cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
1458 struct io_context *ioc = NULL;
1459 struct cfq_io_context *cic;
1461 might_sleep_if(gfp_mask & __GFP_WAIT);
1463 ioc = get_io_context(gfp_mask);
1468 if ((cic = ioc->cic) == NULL) {
1469 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1475 * manually increment generic io_context usage count, it
1476 * cannot go away since we are already holding one ref to it
1480 read_lock(&cfq_exit_lock);
1481 ioc->set_ioprio = cfq_ioc_set_ioprio;
1483 list_add(&cic->queue_list, &cfqd->cic_list);
1484 read_unlock(&cfq_exit_lock);
1486 struct cfq_io_context *__cic;
1489 * the first cic on the list is actually the head itself
1491 if (cic->key == cfqd)
1494 if (unlikely(!cic->key)) {
1495 read_lock(&cfq_exit_lock);
1496 if (list_empty(&cic->list))
1499 ioc->cic = list_entry(cic->list.next,
1500 struct cfq_io_context,
1502 read_unlock(&cfq_exit_lock);
1503 kmem_cache_free(cfq_ioc_pool, cic);
1508 * cic exists, check if we already are there. linear search
1509 * should be ok here, the list will usually not be more than
1510 * 1 or a few entries long
1512 list_for_each_entry(__cic, &cic->list, list) {
1514 * this process is already holding a reference to
1515 * this queue, so no need to get one more
1517 if (__cic->key == cfqd) {
1521 if (unlikely(!__cic->key)) {
1522 read_lock(&cfq_exit_lock);
1523 list_del(&__cic->list);
1524 read_unlock(&cfq_exit_lock);
1525 kmem_cache_free(cfq_ioc_pool, __cic);
1531 * nope, process doesn't have a cic assoicated with this
1532 * cfqq yet. get a new one and add to list
1534 __cic = cfq_alloc_io_context(cfqd, gfp_mask);
1540 read_lock(&cfq_exit_lock);
1541 list_add(&__cic->list, &cic->list);
1542 list_add(&__cic->queue_list, &cfqd->cic_list);
1543 read_unlock(&cfq_exit_lock);
1550 put_io_context(ioc);
1555 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1557 unsigned long elapsed, ttime;
1560 * if this context already has stuff queued, thinktime is from
1561 * last queue not last end
1564 if (time_after(cic->last_end_request, cic->last_queue))
1565 elapsed = jiffies - cic->last_end_request;
1567 elapsed = jiffies - cic->last_queue;
1569 elapsed = jiffies - cic->last_end_request;
1572 ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1574 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1575 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1576 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1579 #define sample_valid(samples) ((samples) > 80)
1582 * Disable idle window if the process thinks too long or seeks so much that
1586 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1587 struct cfq_io_context *cic)
1589 int enable_idle = cfq_cfqq_idle_window(cfqq);
1591 if (!cic->ioc->task || !cfqd->cfq_slice_idle)
1593 else if (sample_valid(cic->ttime_samples)) {
1594 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1601 cfq_mark_cfqq_idle_window(cfqq);
1603 cfq_clear_cfqq_idle_window(cfqq);
1608 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1609 * no or if we aren't sure, a 1 will cause a preempt.
1612 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1615 struct cfq_queue *cfqq = cfqd->active_queue;
1617 if (cfq_class_idle(new_cfqq))
1623 if (cfq_class_idle(cfqq))
1625 if (!cfq_cfqq_wait_request(new_cfqq))
1628 * if it doesn't have slice left, forget it
1630 if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
1632 if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
1639 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1640 * let it have half of its nominal slice.
1642 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1644 struct cfq_queue *__cfqq, *next;
1646 list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
1647 cfq_resort_rr_list(__cfqq, 1);
1649 if (!cfqq->slice_left)
1650 cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
1652 cfqq->slice_end = cfqq->slice_left + jiffies;
1653 __cfq_slice_expired(cfqd, cfqq, 1);
1654 __cfq_set_active_queue(cfqd, cfqq);
1658 * should really be a ll_rw_blk.c helper
1660 static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1662 request_queue_t *q = cfqd->queue;
1664 if (!blk_queue_plugged(q))
1667 __generic_unplug_device(q);
1671 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1672 * something we should do about it
1675 cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1678 struct cfq_io_context *cic;
1680 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
1683 * we never wait for an async request and we don't allow preemption
1684 * of an async request. so just return early
1686 if (!cfq_crq_is_sync(crq))
1689 cic = crq->io_context;
1691 cfq_update_io_thinktime(cfqd, cic);
1692 cfq_update_idle_window(cfqd, cfqq, cic);
1694 cic->last_queue = jiffies;
1696 if (cfqq == cfqd->active_queue) {
1698 * if we are waiting for a request for this queue, let it rip
1699 * immediately and flag that we must not expire this queue
1702 if (cfq_cfqq_wait_request(cfqq)) {
1703 cfq_mark_cfqq_must_dispatch(cfqq);
1704 del_timer(&cfqd->idle_slice_timer);
1705 cfq_start_queueing(cfqd, cfqq);
1707 } else if (cfq_should_preempt(cfqd, cfqq, crq)) {
1709 * not the active queue - expire current slice if it is
1710 * idle and has expired it's mean thinktime or this new queue
1711 * has some old slice time left and is of higher priority
1713 cfq_preempt_queue(cfqd, cfqq);
1714 cfq_mark_cfqq_must_dispatch(cfqq);
1715 cfq_start_queueing(cfqd, cfqq);
1719 static void cfq_insert_request(request_queue_t *q, struct request *rq)
1721 struct cfq_data *cfqd = q->elevator->elevator_data;
1722 struct cfq_rq *crq = RQ_DATA(rq);
1723 struct cfq_queue *cfqq = crq->cfq_queue;
1725 cfq_init_prio_data(cfqq);
1727 cfq_add_crq_rb(crq);
1729 list_add_tail(&rq->queuelist, &cfqq->fifo);
1731 if (rq_mergeable(rq))
1732 cfq_add_crq_hash(cfqd, crq);
1734 cfq_crq_enqueued(cfqd, cfqq, crq);
1737 static void cfq_completed_request(request_queue_t *q, struct request *rq)
1739 struct cfq_rq *crq = RQ_DATA(rq);
1740 struct cfq_queue *cfqq = crq->cfq_queue;
1741 struct cfq_data *cfqd = cfqq->cfqd;
1742 const int sync = cfq_crq_is_sync(crq);
1747 WARN_ON(!cfqd->rq_in_driver);
1748 WARN_ON(!cfqq->on_dispatch[sync]);
1749 cfqd->rq_in_driver--;
1750 cfqq->on_dispatch[sync]--;
1752 if (!cfq_class_idle(cfqq))
1753 cfqd->last_end_request = now;
1755 if (!cfq_cfqq_dispatched(cfqq)) {
1756 if (cfq_cfqq_on_rr(cfqq)) {
1757 cfqq->service_last = now;
1758 cfq_resort_rr_list(cfqq, 0);
1760 cfq_schedule_dispatch(cfqd);
1763 if (cfq_crq_is_sync(crq))
1764 crq->io_context->last_end_request = now;
1767 static struct request *
1768 cfq_former_request(request_queue_t *q, struct request *rq)
1770 struct cfq_rq *crq = RQ_DATA(rq);
1771 struct rb_node *rbprev = rb_prev(&crq->rb_node);
1774 return rb_entry_crq(rbprev)->request;
1779 static struct request *
1780 cfq_latter_request(request_queue_t *q, struct request *rq)
1782 struct cfq_rq *crq = RQ_DATA(rq);
1783 struct rb_node *rbnext = rb_next(&crq->rb_node);
1786 return rb_entry_crq(rbnext)->request;
1792 * we temporarily boost lower priority queues if they are holding fs exclusive
1793 * resources. they are boosted to normal prio (CLASS_BE/4)
1795 static void cfq_prio_boost(struct cfq_queue *cfqq)
1797 const int ioprio_class = cfqq->ioprio_class;
1798 const int ioprio = cfqq->ioprio;
1800 if (has_fs_excl()) {
1802 * boost idle prio on transactions that would lock out other
1803 * users of the filesystem
1805 if (cfq_class_idle(cfqq))
1806 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1807 if (cfqq->ioprio > IOPRIO_NORM)
1808 cfqq->ioprio = IOPRIO_NORM;
1811 * check if we need to unboost the queue
1813 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
1814 cfqq->ioprio_class = cfqq->org_ioprio_class;
1815 if (cfqq->ioprio != cfqq->org_ioprio)
1816 cfqq->ioprio = cfqq->org_ioprio;
1820 * refile between round-robin lists if we moved the priority class
1822 if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) &&
1823 cfq_cfqq_on_rr(cfqq))
1824 cfq_resort_rr_list(cfqq, 0);
1827 static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
1829 if (rw == READ || process_sync(task))
1832 return CFQ_KEY_ASYNC;
1836 __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1837 struct task_struct *task, int rw)
1840 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
1841 !cfq_cfqq_must_alloc_slice(cfqq)) {
1842 cfq_mark_cfqq_must_alloc_slice(cfqq);
1843 return ELV_MQUEUE_MUST;
1846 return ELV_MQUEUE_MAY;
1848 if (!cfqq || task->flags & PF_MEMALLOC)
1849 return ELV_MQUEUE_MAY;
1850 if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) {
1851 if (cfq_cfqq_wait_request(cfqq))
1852 return ELV_MQUEUE_MUST;
1855 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1856 * can quickly flood the queue with writes from a single task
1858 if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) {
1859 cfq_mark_cfqq_must_alloc_slice(cfqq);
1860 return ELV_MQUEUE_MUST;
1863 return ELV_MQUEUE_MAY;
1865 if (cfq_class_idle(cfqq))
1866 return ELV_MQUEUE_NO;
1867 if (cfqq->allocated[rw] >= cfqd->max_queued) {
1868 struct io_context *ioc = get_io_context(GFP_ATOMIC);
1869 int ret = ELV_MQUEUE_NO;
1871 if (ioc && ioc->nr_batch_requests)
1872 ret = ELV_MQUEUE_MAY;
1874 put_io_context(ioc);
1878 return ELV_MQUEUE_MAY;
1882 static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio)
1884 struct cfq_data *cfqd = q->elevator->elevator_data;
1885 struct task_struct *tsk = current;
1886 struct cfq_queue *cfqq;
1889 * don't force setup of a queue from here, as a call to may_queue
1890 * does not necessarily imply that a request actually will be queued.
1891 * so just lookup a possibly existing queue, or return 'may queue'
1894 cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio);
1896 cfq_init_prio_data(cfqq);
1897 cfq_prio_boost(cfqq);
1899 return __cfq_may_queue(cfqd, cfqq, tsk, rw);
1902 return ELV_MQUEUE_MAY;
1905 static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
1907 struct cfq_data *cfqd = q->elevator->elevator_data;
1908 struct request_list *rl = &q->rq;
1910 if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) {
1912 if (waitqueue_active(&rl->wait[READ]))
1913 wake_up(&rl->wait[READ]);
1916 if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) {
1918 if (waitqueue_active(&rl->wait[WRITE]))
1919 wake_up(&rl->wait[WRITE]);
1924 * queue lock held here
1926 static void cfq_put_request(request_queue_t *q, struct request *rq)
1928 struct cfq_data *cfqd = q->elevator->elevator_data;
1929 struct cfq_rq *crq = RQ_DATA(rq);
1932 struct cfq_queue *cfqq = crq->cfq_queue;
1933 const int rw = rq_data_dir(rq);
1935 BUG_ON(!cfqq->allocated[rw]);
1936 cfqq->allocated[rw]--;
1938 put_io_context(crq->io_context->ioc);
1940 mempool_free(crq, cfqd->crq_pool);
1941 rq->elevator_private = NULL;
1943 cfq_check_waiters(q, cfqq);
1944 cfq_put_queue(cfqq);
1949 * Allocate cfq data structures associated with this request.
1952 cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
1955 struct cfq_data *cfqd = q->elevator->elevator_data;
1956 struct task_struct *tsk = current;
1957 struct cfq_io_context *cic;
1958 const int rw = rq_data_dir(rq);
1959 pid_t key = cfq_queue_pid(tsk, rw);
1960 struct cfq_queue *cfqq;
1962 unsigned long flags;
1963 int is_sync = key != CFQ_KEY_ASYNC;
1965 might_sleep_if(gfp_mask & __GFP_WAIT);
1967 cic = cfq_get_io_context(cfqd, key, gfp_mask);
1969 spin_lock_irqsave(q->queue_lock, flags);
1974 if (!cic->cfqq[is_sync]) {
1975 cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
1979 cic->cfqq[is_sync] = cfqq;
1981 cfqq = cic->cfqq[is_sync];
1983 cfqq->allocated[rw]++;
1984 cfq_clear_cfqq_must_alloc(cfqq);
1985 cfqd->rq_starved = 0;
1986 atomic_inc(&cfqq->ref);
1987 spin_unlock_irqrestore(q->queue_lock, flags);
1989 crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
1991 RB_CLEAR(&crq->rb_node);
1994 INIT_HLIST_NODE(&crq->hash);
1995 crq->cfq_queue = cfqq;
1996 crq->io_context = cic;
1999 cfq_mark_crq_is_sync(crq);
2001 cfq_clear_crq_is_sync(crq);
2003 rq->elevator_private = crq;
2007 spin_lock_irqsave(q->queue_lock, flags);
2008 cfqq->allocated[rw]--;
2009 if (!(cfqq->allocated[0] + cfqq->allocated[1]))
2010 cfq_mark_cfqq_must_alloc(cfqq);
2011 cfq_put_queue(cfqq);
2014 put_io_context(cic->ioc);
2016 * mark us rq allocation starved. we need to kickstart the process
2017 * ourselves if there are no pending requests that can do it for us.
2018 * that would be an extremely rare OOM situation
2020 cfqd->rq_starved = 1;
2021 cfq_schedule_dispatch(cfqd);
2022 spin_unlock_irqrestore(q->queue_lock, flags);
2026 static void cfq_kick_queue(void *data)
2028 request_queue_t *q = data;
2029 struct cfq_data *cfqd = q->elevator->elevator_data;
2030 unsigned long flags;
2032 spin_lock_irqsave(q->queue_lock, flags);
2034 if (cfqd->rq_starved) {
2035 struct request_list *rl = &q->rq;
2038 * we aren't guaranteed to get a request after this, but we
2039 * have to be opportunistic
2042 if (waitqueue_active(&rl->wait[READ]))
2043 wake_up(&rl->wait[READ]);
2044 if (waitqueue_active(&rl->wait[WRITE]))
2045 wake_up(&rl->wait[WRITE]);
2050 spin_unlock_irqrestore(q->queue_lock, flags);
2054 * Timer running if the active_queue is currently idling inside its time slice
2056 static void cfq_idle_slice_timer(unsigned long data)
2058 struct cfq_data *cfqd = (struct cfq_data *) data;
2059 struct cfq_queue *cfqq;
2060 unsigned long flags;
2062 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2064 if ((cfqq = cfqd->active_queue) != NULL) {
2065 unsigned long now = jiffies;
2070 if (time_after(now, cfqq->slice_end))
2074 * only expire and reinvoke request handler, if there are
2075 * other queues with pending requests
2077 if (!cfqd->busy_queues) {
2078 cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
2079 add_timer(&cfqd->idle_slice_timer);
2084 * not expired and it has a request pending, let it dispatch
2086 if (!RB_EMPTY(&cfqq->sort_list)) {
2087 cfq_mark_cfqq_must_dispatch(cfqq);
2092 cfq_slice_expired(cfqd, 0);
2094 cfq_schedule_dispatch(cfqd);
2096 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2100 * Timer running if an idle class queue is waiting for service
2102 static void cfq_idle_class_timer(unsigned long data)
2104 struct cfq_data *cfqd = (struct cfq_data *) data;
2105 unsigned long flags, end;
2107 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2110 * race with a non-idle queue, reset timer
2112 end = cfqd->last_end_request + CFQ_IDLE_GRACE;
2113 if (!time_after_eq(jiffies, end)) {
2114 cfqd->idle_class_timer.expires = end;
2115 add_timer(&cfqd->idle_class_timer);
2117 cfq_schedule_dispatch(cfqd);
2119 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2122 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2124 del_timer_sync(&cfqd->idle_slice_timer);
2125 del_timer_sync(&cfqd->idle_class_timer);
2126 blk_sync_queue(cfqd->queue);
2129 static void cfq_put_cfqd(struct cfq_data *cfqd)
2131 if (!atomic_dec_and_test(&cfqd->ref))
2134 cfq_shutdown_timer_wq(cfqd);
2136 mempool_destroy(cfqd->crq_pool);
2137 kfree(cfqd->crq_hash);
2138 kfree(cfqd->cfq_hash);
2142 static void cfq_exit_queue(elevator_t *e)
2144 struct cfq_data *cfqd = e->elevator_data;
2145 request_queue_t *q = cfqd->queue;
2147 cfq_shutdown_timer_wq(cfqd);
2148 write_lock(&cfq_exit_lock);
2149 spin_lock_irq(q->queue_lock);
2150 if (cfqd->active_queue)
2151 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2152 while(!list_empty(&cfqd->cic_list)) {
2153 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2154 struct cfq_io_context,
2156 if (cic->cfqq[ASYNC]) {
2157 cfq_put_queue(cic->cfqq[ASYNC]);
2158 cic->cfqq[ASYNC] = NULL;
2160 if (cic->cfqq[SYNC]) {
2161 cfq_put_queue(cic->cfqq[SYNC]);
2162 cic->cfqq[SYNC] = NULL;
2165 list_del_init(&cic->queue_list);
2167 spin_unlock_irq(q->queue_lock);
2168 write_unlock(&cfq_exit_lock);
2172 static int cfq_init_queue(request_queue_t *q, elevator_t *e)
2174 struct cfq_data *cfqd;
2177 cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
2181 memset(cfqd, 0, sizeof(*cfqd));
2183 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2184 INIT_LIST_HEAD(&cfqd->rr_list[i]);
2186 INIT_LIST_HEAD(&cfqd->busy_rr);
2187 INIT_LIST_HEAD(&cfqd->cur_rr);
2188 INIT_LIST_HEAD(&cfqd->idle_rr);
2189 INIT_LIST_HEAD(&cfqd->empty_list);
2190 INIT_LIST_HEAD(&cfqd->cic_list);
2192 cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
2193 if (!cfqd->crq_hash)
2196 cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
2197 if (!cfqd->cfq_hash)
2200 cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
2201 if (!cfqd->crq_pool)
2204 for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
2205 INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
2206 for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
2207 INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
2209 e->elevator_data = cfqd;
2213 cfqd->max_queued = q->nr_requests / 4;
2214 q->nr_batching = cfq_queued;
2216 init_timer(&cfqd->idle_slice_timer);
2217 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2218 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2220 init_timer(&cfqd->idle_class_timer);
2221 cfqd->idle_class_timer.function = cfq_idle_class_timer;
2222 cfqd->idle_class_timer.data = (unsigned long) cfqd;
2224 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
2226 atomic_set(&cfqd->ref, 1);
2228 cfqd->cfq_queued = cfq_queued;
2229 cfqd->cfq_quantum = cfq_quantum;
2230 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2231 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2232 cfqd->cfq_back_max = cfq_back_max;
2233 cfqd->cfq_back_penalty = cfq_back_penalty;
2234 cfqd->cfq_slice[0] = cfq_slice_async;
2235 cfqd->cfq_slice[1] = cfq_slice_sync;
2236 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2237 cfqd->cfq_slice_idle = cfq_slice_idle;
2238 cfqd->cfq_max_depth = cfq_max_depth;
2242 kfree(cfqd->cfq_hash);
2244 kfree(cfqd->crq_hash);
2250 static void cfq_slab_kill(void)
2253 kmem_cache_destroy(crq_pool);
2255 kmem_cache_destroy(cfq_pool);
2257 kmem_cache_destroy(cfq_ioc_pool);
2260 static int __init cfq_slab_setup(void)
2262 crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
2267 cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
2272 cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
2273 sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
2284 * sysfs parts below -->
2286 struct cfq_fs_entry {
2287 struct attribute attr;
2288 ssize_t (*show)(struct cfq_data *, char *);
2289 ssize_t (*store)(struct cfq_data *, const char *, size_t);
2293 cfq_var_show(unsigned int var, char *page)
2295 return sprintf(page, "%d\n", var);
2299 cfq_var_store(unsigned int *var, const char *page, size_t count)
2301 char *p = (char *) page;
2303 *var = simple_strtoul(p, &p, 10);
2307 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2308 static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2310 unsigned int __data = __VAR; \
2312 __data = jiffies_to_msecs(__data); \
2313 return cfq_var_show(__data, (page)); \
2315 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2316 SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
2317 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2318 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2319 SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0);
2320 SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0);
2321 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2322 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2323 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2324 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2325 SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
2326 #undef SHOW_FUNCTION
2328 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2329 static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2331 unsigned int __data; \
2332 int ret = cfq_var_store(&__data, (page), count); \
2333 if (__data < (MIN)) \
2335 else if (__data > (MAX)) \
2338 *(__PTR) = msecs_to_jiffies(__data); \
2340 *(__PTR) = __data; \
2343 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2344 STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
2345 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1);
2346 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1);
2347 STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2348 STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0);
2349 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2350 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2351 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2352 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0);
2353 STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
2354 #undef STORE_FUNCTION
2356 static struct cfq_fs_entry cfq_quantum_entry = {
2357 .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
2358 .show = cfq_quantum_show,
2359 .store = cfq_quantum_store,
2361 static struct cfq_fs_entry cfq_queued_entry = {
2362 .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
2363 .show = cfq_queued_show,
2364 .store = cfq_queued_store,
2366 static struct cfq_fs_entry cfq_fifo_expire_sync_entry = {
2367 .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
2368 .show = cfq_fifo_expire_sync_show,
2369 .store = cfq_fifo_expire_sync_store,
2371 static struct cfq_fs_entry cfq_fifo_expire_async_entry = {
2372 .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
2373 .show = cfq_fifo_expire_async_show,
2374 .store = cfq_fifo_expire_async_store,
2376 static struct cfq_fs_entry cfq_back_max_entry = {
2377 .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
2378 .show = cfq_back_max_show,
2379 .store = cfq_back_max_store,
2381 static struct cfq_fs_entry cfq_back_penalty_entry = {
2382 .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
2383 .show = cfq_back_penalty_show,
2384 .store = cfq_back_penalty_store,
2386 static struct cfq_fs_entry cfq_slice_sync_entry = {
2387 .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR },
2388 .show = cfq_slice_sync_show,
2389 .store = cfq_slice_sync_store,
2391 static struct cfq_fs_entry cfq_slice_async_entry = {
2392 .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR },
2393 .show = cfq_slice_async_show,
2394 .store = cfq_slice_async_store,
2396 static struct cfq_fs_entry cfq_slice_async_rq_entry = {
2397 .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR },
2398 .show = cfq_slice_async_rq_show,
2399 .store = cfq_slice_async_rq_store,
2401 static struct cfq_fs_entry cfq_slice_idle_entry = {
2402 .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR },
2403 .show = cfq_slice_idle_show,
2404 .store = cfq_slice_idle_store,
2406 static struct cfq_fs_entry cfq_max_depth_entry = {
2407 .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR },
2408 .show = cfq_max_depth_show,
2409 .store = cfq_max_depth_store,
2412 static struct attribute *default_attrs[] = {
2413 &cfq_quantum_entry.attr,
2414 &cfq_queued_entry.attr,
2415 &cfq_fifo_expire_sync_entry.attr,
2416 &cfq_fifo_expire_async_entry.attr,
2417 &cfq_back_max_entry.attr,
2418 &cfq_back_penalty_entry.attr,
2419 &cfq_slice_sync_entry.attr,
2420 &cfq_slice_async_entry.attr,
2421 &cfq_slice_async_rq_entry.attr,
2422 &cfq_slice_idle_entry.attr,
2423 &cfq_max_depth_entry.attr,
2427 #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2430 cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
2432 elevator_t *e = container_of(kobj, elevator_t, kobj);
2433 struct cfq_fs_entry *entry = to_cfq(attr);
2438 return entry->show(e->elevator_data, page);
2442 cfq_attr_store(struct kobject *kobj, struct attribute *attr,
2443 const char *page, size_t length)
2445 elevator_t *e = container_of(kobj, elevator_t, kobj);
2446 struct cfq_fs_entry *entry = to_cfq(attr);
2451 return entry->store(e->elevator_data, page, length);
2454 static struct sysfs_ops cfq_sysfs_ops = {
2455 .show = cfq_attr_show,
2456 .store = cfq_attr_store,
2459 static struct kobj_type cfq_ktype = {
2460 .sysfs_ops = &cfq_sysfs_ops,
2461 .default_attrs = default_attrs,
2464 static struct elevator_type iosched_cfq = {
2466 .elevator_merge_fn = cfq_merge,
2467 .elevator_merged_fn = cfq_merged_request,
2468 .elevator_merge_req_fn = cfq_merged_requests,
2469 .elevator_dispatch_fn = cfq_dispatch_requests,
2470 .elevator_add_req_fn = cfq_insert_request,
2471 .elevator_activate_req_fn = cfq_activate_request,
2472 .elevator_deactivate_req_fn = cfq_deactivate_request,
2473 .elevator_queue_empty_fn = cfq_queue_empty,
2474 .elevator_completed_req_fn = cfq_completed_request,
2475 .elevator_former_req_fn = cfq_former_request,
2476 .elevator_latter_req_fn = cfq_latter_request,
2477 .elevator_set_req_fn = cfq_set_request,
2478 .elevator_put_req_fn = cfq_put_request,
2479 .elevator_may_queue_fn = cfq_may_queue,
2480 .elevator_init_fn = cfq_init_queue,
2481 .elevator_exit_fn = cfq_exit_queue,
2484 .elevator_ktype = &cfq_ktype,
2485 .elevator_name = "cfq",
2486 .elevator_owner = THIS_MODULE,
2489 static int __init cfq_init(void)
2494 * could be 0 on HZ < 1000 setups
2496 if (!cfq_slice_async)
2497 cfq_slice_async = 1;
2498 if (!cfq_slice_idle)
2501 if (cfq_slab_setup())
2504 ret = elv_register(&iosched_cfq);
2511 static void __exit cfq_exit(void)
2513 elv_unregister(&iosched_cfq);
2517 module_init(cfq_init);
2518 module_exit(cfq_exit);
2520 MODULE_AUTHOR("Jens Axboe");
2521 MODULE_LICENSE("GPL");
2522 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");