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 static atomic_t ioc_count = ATOMIC_INIT(0);
95 static struct completion *ioc_gone;
97 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
98 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
99 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
100 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
105 #define cfq_cfqq_dispatched(cfqq) \
106 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
108 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
110 #define cfq_cfqq_sync(cfqq) \
111 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
114 * Per block device queue structure
118 request_queue_t *queue;
121 * rr list of queues with requests and the count of them
123 struct list_head rr_list[CFQ_PRIO_LISTS];
124 struct list_head busy_rr;
125 struct list_head cur_rr;
126 struct list_head idle_rr;
127 unsigned int busy_queues;
130 * non-ordered list of empty cfqq's
132 struct list_head empty_list;
137 struct hlist_head *cfq_hash;
140 * global crq hash for all queues
142 struct hlist_head *crq_hash;
144 unsigned int max_queued;
151 * schedule slice state info
154 * idle window management
156 struct timer_list idle_slice_timer;
157 struct work_struct unplug_work;
159 struct cfq_queue *active_queue;
160 struct cfq_io_context *active_cic;
161 int cur_prio, cur_end_prio;
162 unsigned int dispatch_slice;
164 struct timer_list idle_class_timer;
166 sector_t last_sector;
167 unsigned long last_end_request;
169 unsigned int rq_starved;
172 * tunables, see top of file
174 unsigned int cfq_quantum;
175 unsigned int cfq_queued;
176 unsigned int cfq_fifo_expire[2];
177 unsigned int cfq_back_penalty;
178 unsigned int cfq_back_max;
179 unsigned int cfq_slice[2];
180 unsigned int cfq_slice_async_rq;
181 unsigned int cfq_slice_idle;
182 unsigned int cfq_max_depth;
184 struct list_head cic_list;
188 * Per process-grouping structure
191 /* reference count */
193 /* parent cfq_data */
194 struct cfq_data *cfqd;
195 /* cfqq lookup hash */
196 struct hlist_node cfq_hash;
199 /* on either rr or empty list of cfqd */
200 struct list_head cfq_list;
201 /* sorted list of pending requests */
202 struct rb_root sort_list;
203 /* if fifo isn't expired, next request to serve */
204 struct cfq_rq *next_crq;
205 /* requests queued in sort_list */
207 /* currently allocated requests */
209 /* fifo list of requests in sort_list */
210 struct list_head fifo;
212 unsigned long slice_start;
213 unsigned long slice_end;
214 unsigned long slice_left;
215 unsigned long service_last;
217 /* number of requests that are on the dispatch list */
220 /* io prio of this group */
221 unsigned short ioprio, org_ioprio;
222 unsigned short ioprio_class, org_ioprio_class;
224 /* various state flags, see below */
229 struct rb_node rb_node;
231 struct request *request;
232 struct hlist_node hash;
234 struct cfq_queue *cfq_queue;
235 struct cfq_io_context *io_context;
237 unsigned int crq_flags;
240 enum cfqq_state_flags {
241 CFQ_CFQQ_FLAG_on_rr = 0,
242 CFQ_CFQQ_FLAG_wait_request,
243 CFQ_CFQQ_FLAG_must_alloc,
244 CFQ_CFQQ_FLAG_must_alloc_slice,
245 CFQ_CFQQ_FLAG_must_dispatch,
246 CFQ_CFQQ_FLAG_fifo_expire,
247 CFQ_CFQQ_FLAG_idle_window,
248 CFQ_CFQQ_FLAG_prio_changed,
251 #define CFQ_CFQQ_FNS(name) \
252 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
254 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
256 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
258 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
260 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
262 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
266 CFQ_CFQQ_FNS(wait_request);
267 CFQ_CFQQ_FNS(must_alloc);
268 CFQ_CFQQ_FNS(must_alloc_slice);
269 CFQ_CFQQ_FNS(must_dispatch);
270 CFQ_CFQQ_FNS(fifo_expire);
271 CFQ_CFQQ_FNS(idle_window);
272 CFQ_CFQQ_FNS(prio_changed);
275 enum cfq_rq_state_flags {
276 CFQ_CRQ_FLAG_is_sync = 0,
279 #define CFQ_CRQ_FNS(name) \
280 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
282 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
284 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
286 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
288 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
290 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
293 CFQ_CRQ_FNS(is_sync);
296 static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
297 static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
298 static void cfq_put_cfqd(struct cfq_data *cfqd);
300 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
303 * lots of deadline iosched dupes, can be abstracted later...
305 static inline void cfq_del_crq_hash(struct cfq_rq *crq)
307 hlist_del_init(&crq->hash);
310 static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
312 const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
314 hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
317 static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
319 struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
320 struct hlist_node *entry, *next;
322 hlist_for_each_safe(entry, next, hash_list) {
323 struct cfq_rq *crq = list_entry_hash(entry);
324 struct request *__rq = crq->request;
326 if (!rq_mergeable(__rq)) {
327 cfq_del_crq_hash(crq);
331 if (rq_hash_key(__rq) == offset)
339 * scheduler run of queue, if there are requests pending and no one in the
340 * driver that will restart queueing
342 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
344 if (cfqd->busy_queues)
345 kblockd_schedule_work(&cfqd->unplug_work);
348 static int cfq_queue_empty(request_queue_t *q)
350 struct cfq_data *cfqd = q->elevator->elevator_data;
352 return !cfqd->busy_queues;
356 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
357 * We choose the request that is closest to the head right now. Distance
358 * behind the head are penalized and only allowed to a certain extent.
360 static struct cfq_rq *
361 cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
363 sector_t last, s1, s2, d1 = 0, d2 = 0;
364 int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
365 unsigned long back_max;
367 if (crq1 == NULL || crq1 == crq2)
372 if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
374 else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
377 s1 = crq1->request->sector;
378 s2 = crq2->request->sector;
380 last = cfqd->last_sector;
383 * by definition, 1KiB is 2 sectors
385 back_max = cfqd->cfq_back_max * 2;
388 * Strict one way elevator _except_ in the case where we allow
389 * short backward seeks which are biased as twice the cost of a
390 * similar forward seek.
394 else if (s1 + back_max >= last)
395 d1 = (last - s1) * cfqd->cfq_back_penalty;
401 else if (s2 + back_max >= last)
402 d2 = (last - s2) * cfqd->cfq_back_penalty;
406 /* Found required data */
407 if (!r1_wrap && r2_wrap)
409 else if (!r2_wrap && r1_wrap)
411 else if (r1_wrap && r2_wrap) {
412 /* both behind the head */
419 /* Both requests in front of the head */
433 * would be nice to take fifo expire time into account as well
435 static struct cfq_rq *
436 cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
439 struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
440 struct rb_node *rbnext, *rbprev;
442 if (!(rbnext = rb_next(&last->rb_node))) {
443 rbnext = rb_first(&cfqq->sort_list);
444 if (rbnext == &last->rb_node)
448 rbprev = rb_prev(&last->rb_node);
451 crq_prev = rb_entry_crq(rbprev);
453 crq_next = rb_entry_crq(rbnext);
455 return cfq_choose_req(cfqd, crq_next, crq_prev);
458 static void cfq_update_next_crq(struct cfq_rq *crq)
460 struct cfq_queue *cfqq = crq->cfq_queue;
462 if (cfqq->next_crq == crq)
463 cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
466 static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
468 struct cfq_data *cfqd = cfqq->cfqd;
469 struct list_head *list, *entry;
471 BUG_ON(!cfq_cfqq_on_rr(cfqq));
473 list_del(&cfqq->cfq_list);
475 if (cfq_class_rt(cfqq))
476 list = &cfqd->cur_rr;
477 else if (cfq_class_idle(cfqq))
478 list = &cfqd->idle_rr;
481 * if cfqq has requests in flight, don't allow it to be
482 * found in cfq_set_active_queue before it has finished them.
483 * this is done to increase fairness between a process that
484 * has lots of io pending vs one that only generates one
485 * sporadically or synchronously
487 if (cfq_cfqq_dispatched(cfqq))
488 list = &cfqd->busy_rr;
490 list = &cfqd->rr_list[cfqq->ioprio];
494 * if queue was preempted, just add to front to be fair. busy_rr
497 if (preempted || list == &cfqd->busy_rr) {
498 list_add(&cfqq->cfq_list, list);
503 * sort by when queue was last serviced
506 while ((entry = entry->prev) != list) {
507 struct cfq_queue *__cfqq = list_entry_cfqq(entry);
509 if (!__cfqq->service_last)
511 if (time_before(__cfqq->service_last, cfqq->service_last))
515 list_add(&cfqq->cfq_list, entry);
519 * add to busy list of queues for service, trying to be fair in ordering
520 * the pending list according to last request service
523 cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
525 BUG_ON(cfq_cfqq_on_rr(cfqq));
526 cfq_mark_cfqq_on_rr(cfqq);
529 cfq_resort_rr_list(cfqq, 0);
533 cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
535 BUG_ON(!cfq_cfqq_on_rr(cfqq));
536 cfq_clear_cfqq_on_rr(cfqq);
537 list_move(&cfqq->cfq_list, &cfqd->empty_list);
539 BUG_ON(!cfqd->busy_queues);
544 * rb tree support functions
546 static inline void cfq_del_crq_rb(struct cfq_rq *crq)
548 struct cfq_queue *cfqq = crq->cfq_queue;
549 struct cfq_data *cfqd = cfqq->cfqd;
550 const int sync = cfq_crq_is_sync(crq);
552 BUG_ON(!cfqq->queued[sync]);
553 cfqq->queued[sync]--;
555 cfq_update_next_crq(crq);
557 rb_erase(&crq->rb_node, &cfqq->sort_list);
558 RB_CLEAR_COLOR(&crq->rb_node);
560 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
561 cfq_del_cfqq_rr(cfqd, cfqq);
564 static struct cfq_rq *
565 __cfq_add_crq_rb(struct cfq_rq *crq)
567 struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
568 struct rb_node *parent = NULL;
569 struct cfq_rq *__crq;
573 __crq = rb_entry_crq(parent);
575 if (crq->rb_key < __crq->rb_key)
577 else if (crq->rb_key > __crq->rb_key)
583 rb_link_node(&crq->rb_node, parent, p);
587 static void cfq_add_crq_rb(struct cfq_rq *crq)
589 struct cfq_queue *cfqq = crq->cfq_queue;
590 struct cfq_data *cfqd = cfqq->cfqd;
591 struct request *rq = crq->request;
592 struct cfq_rq *__alias;
594 crq->rb_key = rq_rb_key(rq);
595 cfqq->queued[cfq_crq_is_sync(crq)]++;
598 * looks a little odd, but the first insert might return an alias.
599 * if that happens, put the alias on the dispatch list
601 while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
602 cfq_dispatch_insert(cfqd->queue, __alias);
604 rb_insert_color(&crq->rb_node, &cfqq->sort_list);
606 if (!cfq_cfqq_on_rr(cfqq))
607 cfq_add_cfqq_rr(cfqd, cfqq);
610 * check if this request is a better next-serve candidate
612 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
616 cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
618 rb_erase(&crq->rb_node, &cfqq->sort_list);
619 cfqq->queued[cfq_crq_is_sync(crq)]--;
624 static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
627 struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
633 n = cfqq->sort_list.rb_node;
635 struct cfq_rq *crq = rb_entry_crq(n);
637 if (sector < crq->rb_key)
639 else if (sector > crq->rb_key)
649 static void cfq_activate_request(request_queue_t *q, struct request *rq)
651 struct cfq_data *cfqd = q->elevator->elevator_data;
653 cfqd->rq_in_driver++;
656 static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
658 struct cfq_data *cfqd = q->elevator->elevator_data;
660 WARN_ON(!cfqd->rq_in_driver);
661 cfqd->rq_in_driver--;
664 static void cfq_remove_request(struct request *rq)
666 struct cfq_rq *crq = RQ_DATA(rq);
668 list_del_init(&rq->queuelist);
670 cfq_del_crq_hash(crq);
674 cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
676 struct cfq_data *cfqd = q->elevator->elevator_data;
677 struct request *__rq;
680 __rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
681 if (__rq && elv_rq_merge_ok(__rq, bio)) {
682 ret = ELEVATOR_BACK_MERGE;
686 __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
687 if (__rq && elv_rq_merge_ok(__rq, bio)) {
688 ret = ELEVATOR_FRONT_MERGE;
692 return ELEVATOR_NO_MERGE;
698 static void cfq_merged_request(request_queue_t *q, struct request *req)
700 struct cfq_data *cfqd = q->elevator->elevator_data;
701 struct cfq_rq *crq = RQ_DATA(req);
703 cfq_del_crq_hash(crq);
704 cfq_add_crq_hash(cfqd, crq);
706 if (rq_rb_key(req) != crq->rb_key) {
707 struct cfq_queue *cfqq = crq->cfq_queue;
709 cfq_update_next_crq(crq);
710 cfq_reposition_crq_rb(cfqq, crq);
715 cfq_merged_requests(request_queue_t *q, struct request *rq,
716 struct request *next)
718 cfq_merged_request(q, rq);
721 * reposition in fifo if next is older than rq
723 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
724 time_before(next->start_time, rq->start_time))
725 list_move(&rq->queuelist, &next->queuelist);
727 cfq_remove_request(next);
731 __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
735 * stop potential idle class queues waiting service
737 del_timer(&cfqd->idle_class_timer);
739 cfqq->slice_start = jiffies;
741 cfqq->slice_left = 0;
742 cfq_clear_cfqq_must_alloc_slice(cfqq);
743 cfq_clear_cfqq_fifo_expire(cfqq);
746 cfqd->active_queue = cfqq;
750 * current cfqq expired its slice (or was too idle), select new one
753 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
756 unsigned long now = jiffies;
758 if (cfq_cfqq_wait_request(cfqq))
759 del_timer(&cfqd->idle_slice_timer);
761 if (!preempted && !cfq_cfqq_dispatched(cfqq)) {
762 cfqq->service_last = now;
763 cfq_schedule_dispatch(cfqd);
766 cfq_clear_cfqq_must_dispatch(cfqq);
767 cfq_clear_cfqq_wait_request(cfqq);
770 * store what was left of this slice, if the queue idled out
773 if (time_after(cfqq->slice_end, now))
774 cfqq->slice_left = cfqq->slice_end - now;
776 cfqq->slice_left = 0;
778 if (cfq_cfqq_on_rr(cfqq))
779 cfq_resort_rr_list(cfqq, preempted);
781 if (cfqq == cfqd->active_queue)
782 cfqd->active_queue = NULL;
784 if (cfqd->active_cic) {
785 put_io_context(cfqd->active_cic->ioc);
786 cfqd->active_cic = NULL;
789 cfqd->dispatch_slice = 0;
792 static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
794 struct cfq_queue *cfqq = cfqd->active_queue;
797 __cfq_slice_expired(cfqd, cfqq, preempted);
810 static int cfq_get_next_prio_level(struct cfq_data *cfqd)
819 for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) {
820 if (!list_empty(&cfqd->rr_list[p])) {
829 if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
830 cfqd->cur_end_prio = 0;
837 if (unlikely(prio == -1))
840 BUG_ON(prio >= CFQ_PRIO_LISTS);
842 list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr);
844 cfqd->cur_prio = prio + 1;
845 if (cfqd->cur_prio > cfqd->cur_end_prio) {
846 cfqd->cur_end_prio = cfqd->cur_prio;
849 if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
851 cfqd->cur_end_prio = 0;
857 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
859 struct cfq_queue *cfqq = NULL;
862 * if current list is non-empty, grab first entry. if it is empty,
863 * get next prio level and grab first entry then if any are spliced
865 if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
866 cfqq = list_entry_cfqq(cfqd->cur_rr.next);
869 * if we have idle queues and no rt or be queues had pending
870 * requests, either allow immediate service if the grace period
871 * has passed or arm the idle grace timer
873 if (!cfqq && !list_empty(&cfqd->idle_rr)) {
874 unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
876 if (time_after_eq(jiffies, end))
877 cfqq = list_entry_cfqq(cfqd->idle_rr.next);
879 mod_timer(&cfqd->idle_class_timer, end);
882 __cfq_set_active_queue(cfqd, cfqq);
886 static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
891 WARN_ON(!RB_EMPTY(&cfqq->sort_list));
892 WARN_ON(cfqq != cfqd->active_queue);
895 * idle is disabled, either manually or by past process history
897 if (!cfqd->cfq_slice_idle)
899 if (!cfq_cfqq_idle_window(cfqq))
902 * task has exited, don't wait
904 if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
907 cfq_mark_cfqq_must_dispatch(cfqq);
908 cfq_mark_cfqq_wait_request(cfqq);
910 sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
911 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
915 static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
917 struct cfq_data *cfqd = q->elevator->elevator_data;
918 struct cfq_queue *cfqq = crq->cfq_queue;
920 cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
921 cfq_remove_request(crq->request);
922 cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
923 elv_dispatch_sort(q, crq->request);
927 * return expired entry, or NULL to just start from scratch in rbtree
929 static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
931 struct cfq_data *cfqd = cfqq->cfqd;
935 if (cfq_cfqq_fifo_expire(cfqq))
938 if (!list_empty(&cfqq->fifo)) {
939 int fifo = cfq_cfqq_class_sync(cfqq);
941 crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next));
943 if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
944 cfq_mark_cfqq_fifo_expire(cfqq);
953 * Scale schedule slice based on io priority. Use the sync time slice only
954 * if a queue is marked sync and has sync io queued. A sync queue with async
955 * io only, should not get full sync slice length.
958 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
960 const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)];
962 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
964 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio));
968 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
970 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
974 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
976 const int base_rq = cfqd->cfq_slice_async_rq;
978 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
980 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
984 * get next queue for service
986 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
988 unsigned long now = jiffies;
989 struct cfq_queue *cfqq;
991 cfqq = cfqd->active_queue;
998 if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end))
1002 * if queue has requests, dispatch one. if not, check if
1003 * enough slice is left to wait for one
1005 if (!RB_EMPTY(&cfqq->sort_list))
1007 else if (cfq_cfqq_class_sync(cfqq) &&
1008 time_before(now, cfqq->slice_end)) {
1009 if (cfq_arm_slice_timer(cfqd, cfqq))
1014 cfq_slice_expired(cfqd, 0);
1016 cfqq = cfq_set_active_queue(cfqd);
1022 __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1027 BUG_ON(RB_EMPTY(&cfqq->sort_list));
1033 * follow expired path, else get first next available
1035 if ((crq = cfq_check_fifo(cfqq)) == NULL)
1036 crq = cfqq->next_crq;
1039 * finally, insert request into driver dispatch list
1041 cfq_dispatch_insert(cfqd->queue, crq);
1043 cfqd->dispatch_slice++;
1046 if (!cfqd->active_cic) {
1047 atomic_inc(&crq->io_context->ioc->refcount);
1048 cfqd->active_cic = crq->io_context;
1051 if (RB_EMPTY(&cfqq->sort_list))
1054 } while (dispatched < max_dispatch);
1057 * if slice end isn't set yet, set it. if at least one request was
1058 * sync, use the sync time slice value
1060 if (!cfqq->slice_end)
1061 cfq_set_prio_slice(cfqd, cfqq);
1064 * expire an async queue immediately if it has used up its slice. idle
1065 * queue always expire after 1 dispatch round.
1067 if ((!cfq_cfqq_sync(cfqq) &&
1068 cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1069 cfq_class_idle(cfqq))
1070 cfq_slice_expired(cfqd, 0);
1076 cfq_forced_dispatch_cfqqs(struct list_head *list)
1079 struct cfq_queue *cfqq, *next;
1082 list_for_each_entry_safe(cfqq, next, list, cfq_list) {
1083 while ((crq = cfqq->next_crq)) {
1084 cfq_dispatch_insert(cfqq->cfqd->queue, crq);
1087 BUG_ON(!list_empty(&cfqq->fifo));
1093 cfq_forced_dispatch(struct cfq_data *cfqd)
1095 int i, dispatched = 0;
1097 for (i = 0; i < CFQ_PRIO_LISTS; i++)
1098 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
1100 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
1101 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
1102 dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
1104 cfq_slice_expired(cfqd, 0);
1106 BUG_ON(cfqd->busy_queues);
1112 cfq_dispatch_requests(request_queue_t *q, int force)
1114 struct cfq_data *cfqd = q->elevator->elevator_data;
1115 struct cfq_queue *cfqq;
1117 if (!cfqd->busy_queues)
1120 if (unlikely(force))
1121 return cfq_forced_dispatch(cfqd);
1123 cfqq = cfq_select_queue(cfqd);
1128 * if idle window is disabled, allow queue buildup
1130 if (!cfq_cfqq_idle_window(cfqq) &&
1131 cfqd->rq_in_driver >= cfqd->cfq_max_depth)
1134 cfq_clear_cfqq_must_dispatch(cfqq);
1135 cfq_clear_cfqq_wait_request(cfqq);
1136 del_timer(&cfqd->idle_slice_timer);
1138 max_dispatch = cfqd->cfq_quantum;
1139 if (cfq_class_idle(cfqq))
1142 return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
1149 * task holds one reference to the queue, dropped when task exits. each crq
1150 * in-flight on this queue also holds a reference, dropped when crq is freed.
1152 * queue lock must be held here.
1154 static void cfq_put_queue(struct cfq_queue *cfqq)
1156 struct cfq_data *cfqd = cfqq->cfqd;
1158 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1160 if (!atomic_dec_and_test(&cfqq->ref))
1163 BUG_ON(rb_first(&cfqq->sort_list));
1164 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1165 BUG_ON(cfq_cfqq_on_rr(cfqq));
1167 if (unlikely(cfqd->active_queue == cfqq))
1168 __cfq_slice_expired(cfqd, cfqq, 0);
1170 cfq_put_cfqd(cfqq->cfqd);
1173 * it's on the empty list and still hashed
1175 list_del(&cfqq->cfq_list);
1176 hlist_del(&cfqq->cfq_hash);
1177 kmem_cache_free(cfq_pool, cfqq);
1180 static inline struct cfq_queue *
1181 __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
1184 struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
1185 struct hlist_node *entry, *next;
1187 hlist_for_each_safe(entry, next, hash_list) {
1188 struct cfq_queue *__cfqq = list_entry_qhash(entry);
1189 const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio);
1191 if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
1198 static struct cfq_queue *
1199 cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
1201 return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
1204 static void cfq_free_io_context(struct cfq_io_context *cic)
1206 struct cfq_io_context *__cic;
1207 struct list_head *entry, *next;
1210 list_for_each_safe(entry, next, &cic->list) {
1211 __cic = list_entry(entry, struct cfq_io_context, list);
1212 kmem_cache_free(cfq_ioc_pool, __cic);
1216 kmem_cache_free(cfq_ioc_pool, cic);
1217 if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone)
1221 static void cfq_trim(struct io_context *ioc)
1223 ioc->set_ioprio = NULL;
1225 cfq_free_io_context(ioc->cic);
1229 * Called with interrupts disabled
1231 static void cfq_exit_single_io_context(struct cfq_io_context *cic)
1233 struct cfq_data *cfqd = cic->key;
1241 WARN_ON(!irqs_disabled());
1243 spin_lock(q->queue_lock);
1245 if (cic->cfqq[ASYNC]) {
1246 if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue))
1247 __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0);
1248 cfq_put_queue(cic->cfqq[ASYNC]);
1249 cic->cfqq[ASYNC] = NULL;
1252 if (cic->cfqq[SYNC]) {
1253 if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue))
1254 __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0);
1255 cfq_put_queue(cic->cfqq[SYNC]);
1256 cic->cfqq[SYNC] = NULL;
1260 list_del_init(&cic->queue_list);
1261 spin_unlock(q->queue_lock);
1265 * Another task may update the task cic list, if it is doing a queue lookup
1266 * on its behalf. cfq_cic_lock excludes such concurrent updates
1268 static void cfq_exit_io_context(struct cfq_io_context *cic)
1270 struct cfq_io_context *__cic;
1271 struct list_head *entry;
1272 unsigned long flags;
1274 local_irq_save(flags);
1277 * put the reference this task is holding to the various queues
1279 read_lock(&cfq_exit_lock);
1280 list_for_each(entry, &cic->list) {
1281 __cic = list_entry(entry, struct cfq_io_context, list);
1282 cfq_exit_single_io_context(__cic);
1285 cfq_exit_single_io_context(cic);
1286 read_unlock(&cfq_exit_lock);
1287 local_irq_restore(flags);
1290 static struct cfq_io_context *
1291 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1293 struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
1296 INIT_LIST_HEAD(&cic->list);
1297 cic->cfqq[ASYNC] = NULL;
1298 cic->cfqq[SYNC] = NULL;
1300 cic->last_end_request = jiffies;
1301 cic->ttime_total = 0;
1302 cic->ttime_samples = 0;
1303 cic->ttime_mean = 0;
1304 cic->dtor = cfq_free_io_context;
1305 cic->exit = cfq_exit_io_context;
1306 INIT_LIST_HEAD(&cic->queue_list);
1307 atomic_inc(&ioc_count);
1313 static void cfq_init_prio_data(struct cfq_queue *cfqq)
1315 struct task_struct *tsk = current;
1318 if (!cfq_cfqq_prio_changed(cfqq))
1321 ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
1322 switch (ioprio_class) {
1324 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1325 case IOPRIO_CLASS_NONE:
1327 * no prio set, place us in the middle of the BE classes
1329 cfqq->ioprio = task_nice_ioprio(tsk);
1330 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1332 case IOPRIO_CLASS_RT:
1333 cfqq->ioprio = task_ioprio(tsk);
1334 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1336 case IOPRIO_CLASS_BE:
1337 cfqq->ioprio = task_ioprio(tsk);
1338 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1340 case IOPRIO_CLASS_IDLE:
1341 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1343 cfq_clear_cfqq_idle_window(cfqq);
1348 * keep track of original prio settings in case we have to temporarily
1349 * elevate the priority of this queue
1351 cfqq->org_ioprio = cfqq->ioprio;
1352 cfqq->org_ioprio_class = cfqq->ioprio_class;
1354 if (cfq_cfqq_on_rr(cfqq))
1355 cfq_resort_rr_list(cfqq, 0);
1357 cfq_clear_cfqq_prio_changed(cfqq);
1360 static inline void changed_ioprio(struct cfq_io_context *cic)
1362 struct cfq_data *cfqd = cic->key;
1363 struct cfq_queue *cfqq;
1365 spin_lock(cfqd->queue->queue_lock);
1366 cfqq = cic->cfqq[ASYNC];
1368 cfq_mark_cfqq_prio_changed(cfqq);
1369 cfq_init_prio_data(cfqq);
1371 cfqq = cic->cfqq[SYNC];
1373 cfq_mark_cfqq_prio_changed(cfqq);
1374 cfq_init_prio_data(cfqq);
1376 spin_unlock(cfqd->queue->queue_lock);
1381 * callback from sys_ioprio_set, irqs are disabled
1383 static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
1385 struct cfq_io_context *cic;
1387 write_lock(&cfq_exit_lock);
1391 changed_ioprio(cic);
1393 list_for_each_entry(cic, &cic->list, list)
1394 changed_ioprio(cic);
1396 write_unlock(&cfq_exit_lock);
1401 static struct cfq_queue *
1402 cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
1405 const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
1406 struct cfq_queue *cfqq, *new_cfqq = NULL;
1409 cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
1415 } else if (gfp_mask & __GFP_WAIT) {
1416 spin_unlock_irq(cfqd->queue->queue_lock);
1417 new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1418 spin_lock_irq(cfqd->queue->queue_lock);
1421 cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1426 memset(cfqq, 0, sizeof(*cfqq));
1428 INIT_HLIST_NODE(&cfqq->cfq_hash);
1429 INIT_LIST_HEAD(&cfqq->cfq_list);
1430 RB_CLEAR_ROOT(&cfqq->sort_list);
1431 INIT_LIST_HEAD(&cfqq->fifo);
1434 hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
1435 atomic_set(&cfqq->ref, 0);
1437 atomic_inc(&cfqd->ref);
1438 cfqq->service_last = 0;
1440 * set ->slice_left to allow preemption for a new process
1442 cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
1443 cfq_mark_cfqq_idle_window(cfqq);
1444 cfq_mark_cfqq_prio_changed(cfqq);
1445 cfq_init_prio_data(cfqq);
1449 kmem_cache_free(cfq_pool, new_cfqq);
1451 atomic_inc(&cfqq->ref);
1453 WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
1458 * Setup general io context and cfq io context. There can be several cfq
1459 * io contexts per general io context, if this process is doing io to more
1460 * than one device managed by cfq. Note that caller is holding a reference to
1461 * cfqq, so we don't need to worry about it disappearing
1463 static struct cfq_io_context *
1464 cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
1466 struct io_context *ioc = NULL;
1467 struct cfq_io_context *cic;
1469 might_sleep_if(gfp_mask & __GFP_WAIT);
1471 ioc = get_io_context(gfp_mask);
1476 if ((cic = ioc->cic) == NULL) {
1477 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1483 * manually increment generic io_context usage count, it
1484 * cannot go away since we are already holding one ref to it
1488 read_lock(&cfq_exit_lock);
1489 ioc->set_ioprio = cfq_ioc_set_ioprio;
1491 list_add(&cic->queue_list, &cfqd->cic_list);
1492 read_unlock(&cfq_exit_lock);
1494 struct cfq_io_context *__cic;
1497 * the first cic on the list is actually the head itself
1499 if (cic->key == cfqd)
1502 if (unlikely(!cic->key)) {
1503 read_lock(&cfq_exit_lock);
1504 if (list_empty(&cic->list))
1507 ioc->cic = list_entry(cic->list.next,
1508 struct cfq_io_context,
1510 read_unlock(&cfq_exit_lock);
1511 kmem_cache_free(cfq_ioc_pool, cic);
1512 atomic_dec(&ioc_count);
1517 * cic exists, check if we already are there. linear search
1518 * should be ok here, the list will usually not be more than
1519 * 1 or a few entries long
1521 list_for_each_entry(__cic, &cic->list, list) {
1523 * this process is already holding a reference to
1524 * this queue, so no need to get one more
1526 if (__cic->key == cfqd) {
1530 if (unlikely(!__cic->key)) {
1531 read_lock(&cfq_exit_lock);
1532 list_del(&__cic->list);
1533 read_unlock(&cfq_exit_lock);
1534 kmem_cache_free(cfq_ioc_pool, __cic);
1535 atomic_dec(&ioc_count);
1541 * nope, process doesn't have a cic assoicated with this
1542 * cfqq yet. get a new one and add to list
1544 __cic = cfq_alloc_io_context(cfqd, gfp_mask);
1550 read_lock(&cfq_exit_lock);
1551 list_add(&__cic->list, &cic->list);
1552 list_add(&__cic->queue_list, &cfqd->cic_list);
1553 read_unlock(&cfq_exit_lock);
1560 put_io_context(ioc);
1565 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1567 unsigned long elapsed, ttime;
1570 * if this context already has stuff queued, thinktime is from
1571 * last queue not last end
1574 if (time_after(cic->last_end_request, cic->last_queue))
1575 elapsed = jiffies - cic->last_end_request;
1577 elapsed = jiffies - cic->last_queue;
1579 elapsed = jiffies - cic->last_end_request;
1582 ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1584 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1585 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1586 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1589 #define sample_valid(samples) ((samples) > 80)
1592 * Disable idle window if the process thinks too long or seeks so much that
1596 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1597 struct cfq_io_context *cic)
1599 int enable_idle = cfq_cfqq_idle_window(cfqq);
1601 if (!cic->ioc->task || !cfqd->cfq_slice_idle)
1603 else if (sample_valid(cic->ttime_samples)) {
1604 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1611 cfq_mark_cfqq_idle_window(cfqq);
1613 cfq_clear_cfqq_idle_window(cfqq);
1618 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1619 * no or if we aren't sure, a 1 will cause a preempt.
1622 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1625 struct cfq_queue *cfqq = cfqd->active_queue;
1627 if (cfq_class_idle(new_cfqq))
1633 if (cfq_class_idle(cfqq))
1635 if (!cfq_cfqq_wait_request(new_cfqq))
1638 * if it doesn't have slice left, forget it
1640 if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
1642 if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
1649 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1650 * let it have half of its nominal slice.
1652 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1654 struct cfq_queue *__cfqq, *next;
1656 list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
1657 cfq_resort_rr_list(__cfqq, 1);
1659 if (!cfqq->slice_left)
1660 cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
1662 cfqq->slice_end = cfqq->slice_left + jiffies;
1663 __cfq_slice_expired(cfqd, cfqq, 1);
1664 __cfq_set_active_queue(cfqd, cfqq);
1668 * should really be a ll_rw_blk.c helper
1670 static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1672 request_queue_t *q = cfqd->queue;
1674 if (!blk_queue_plugged(q))
1677 __generic_unplug_device(q);
1681 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1682 * something we should do about it
1685 cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1688 struct cfq_io_context *cic;
1690 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
1693 * we never wait for an async request and we don't allow preemption
1694 * of an async request. so just return early
1696 if (!cfq_crq_is_sync(crq))
1699 cic = crq->io_context;
1701 cfq_update_io_thinktime(cfqd, cic);
1702 cfq_update_idle_window(cfqd, cfqq, cic);
1704 cic->last_queue = jiffies;
1706 if (cfqq == cfqd->active_queue) {
1708 * if we are waiting for a request for this queue, let it rip
1709 * immediately and flag that we must not expire this queue
1712 if (cfq_cfqq_wait_request(cfqq)) {
1713 cfq_mark_cfqq_must_dispatch(cfqq);
1714 del_timer(&cfqd->idle_slice_timer);
1715 cfq_start_queueing(cfqd, cfqq);
1717 } else if (cfq_should_preempt(cfqd, cfqq, crq)) {
1719 * not the active queue - expire current slice if it is
1720 * idle and has expired it's mean thinktime or this new queue
1721 * has some old slice time left and is of higher priority
1723 cfq_preempt_queue(cfqd, cfqq);
1724 cfq_mark_cfqq_must_dispatch(cfqq);
1725 cfq_start_queueing(cfqd, cfqq);
1729 static void cfq_insert_request(request_queue_t *q, struct request *rq)
1731 struct cfq_data *cfqd = q->elevator->elevator_data;
1732 struct cfq_rq *crq = RQ_DATA(rq);
1733 struct cfq_queue *cfqq = crq->cfq_queue;
1735 cfq_init_prio_data(cfqq);
1737 cfq_add_crq_rb(crq);
1739 list_add_tail(&rq->queuelist, &cfqq->fifo);
1741 if (rq_mergeable(rq))
1742 cfq_add_crq_hash(cfqd, crq);
1744 cfq_crq_enqueued(cfqd, cfqq, crq);
1747 static void cfq_completed_request(request_queue_t *q, struct request *rq)
1749 struct cfq_rq *crq = RQ_DATA(rq);
1750 struct cfq_queue *cfqq = crq->cfq_queue;
1751 struct cfq_data *cfqd = cfqq->cfqd;
1752 const int sync = cfq_crq_is_sync(crq);
1757 WARN_ON(!cfqd->rq_in_driver);
1758 WARN_ON(!cfqq->on_dispatch[sync]);
1759 cfqd->rq_in_driver--;
1760 cfqq->on_dispatch[sync]--;
1762 if (!cfq_class_idle(cfqq))
1763 cfqd->last_end_request = now;
1765 if (!cfq_cfqq_dispatched(cfqq)) {
1766 if (cfq_cfqq_on_rr(cfqq)) {
1767 cfqq->service_last = now;
1768 cfq_resort_rr_list(cfqq, 0);
1770 cfq_schedule_dispatch(cfqd);
1773 if (cfq_crq_is_sync(crq))
1774 crq->io_context->last_end_request = now;
1777 static struct request *
1778 cfq_former_request(request_queue_t *q, struct request *rq)
1780 struct cfq_rq *crq = RQ_DATA(rq);
1781 struct rb_node *rbprev = rb_prev(&crq->rb_node);
1784 return rb_entry_crq(rbprev)->request;
1789 static struct request *
1790 cfq_latter_request(request_queue_t *q, struct request *rq)
1792 struct cfq_rq *crq = RQ_DATA(rq);
1793 struct rb_node *rbnext = rb_next(&crq->rb_node);
1796 return rb_entry_crq(rbnext)->request;
1802 * we temporarily boost lower priority queues if they are holding fs exclusive
1803 * resources. they are boosted to normal prio (CLASS_BE/4)
1805 static void cfq_prio_boost(struct cfq_queue *cfqq)
1807 const int ioprio_class = cfqq->ioprio_class;
1808 const int ioprio = cfqq->ioprio;
1810 if (has_fs_excl()) {
1812 * boost idle prio on transactions that would lock out other
1813 * users of the filesystem
1815 if (cfq_class_idle(cfqq))
1816 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1817 if (cfqq->ioprio > IOPRIO_NORM)
1818 cfqq->ioprio = IOPRIO_NORM;
1821 * check if we need to unboost the queue
1823 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
1824 cfqq->ioprio_class = cfqq->org_ioprio_class;
1825 if (cfqq->ioprio != cfqq->org_ioprio)
1826 cfqq->ioprio = cfqq->org_ioprio;
1830 * refile between round-robin lists if we moved the priority class
1832 if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) &&
1833 cfq_cfqq_on_rr(cfqq))
1834 cfq_resort_rr_list(cfqq, 0);
1837 static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
1839 if (rw == READ || process_sync(task))
1842 return CFQ_KEY_ASYNC;
1846 __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1847 struct task_struct *task, int rw)
1850 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
1851 !cfq_cfqq_must_alloc_slice(cfqq)) {
1852 cfq_mark_cfqq_must_alloc_slice(cfqq);
1853 return ELV_MQUEUE_MUST;
1856 return ELV_MQUEUE_MAY;
1858 if (!cfqq || task->flags & PF_MEMALLOC)
1859 return ELV_MQUEUE_MAY;
1860 if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) {
1861 if (cfq_cfqq_wait_request(cfqq))
1862 return ELV_MQUEUE_MUST;
1865 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1866 * can quickly flood the queue with writes from a single task
1868 if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) {
1869 cfq_mark_cfqq_must_alloc_slice(cfqq);
1870 return ELV_MQUEUE_MUST;
1873 return ELV_MQUEUE_MAY;
1875 if (cfq_class_idle(cfqq))
1876 return ELV_MQUEUE_NO;
1877 if (cfqq->allocated[rw] >= cfqd->max_queued) {
1878 struct io_context *ioc = get_io_context(GFP_ATOMIC);
1879 int ret = ELV_MQUEUE_NO;
1881 if (ioc && ioc->nr_batch_requests)
1882 ret = ELV_MQUEUE_MAY;
1884 put_io_context(ioc);
1888 return ELV_MQUEUE_MAY;
1892 static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio)
1894 struct cfq_data *cfqd = q->elevator->elevator_data;
1895 struct task_struct *tsk = current;
1896 struct cfq_queue *cfqq;
1899 * don't force setup of a queue from here, as a call to may_queue
1900 * does not necessarily imply that a request actually will be queued.
1901 * so just lookup a possibly existing queue, or return 'may queue'
1904 cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio);
1906 cfq_init_prio_data(cfqq);
1907 cfq_prio_boost(cfqq);
1909 return __cfq_may_queue(cfqd, cfqq, tsk, rw);
1912 return ELV_MQUEUE_MAY;
1915 static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
1917 struct cfq_data *cfqd = q->elevator->elevator_data;
1918 struct request_list *rl = &q->rq;
1920 if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) {
1922 if (waitqueue_active(&rl->wait[READ]))
1923 wake_up(&rl->wait[READ]);
1926 if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) {
1928 if (waitqueue_active(&rl->wait[WRITE]))
1929 wake_up(&rl->wait[WRITE]);
1934 * queue lock held here
1936 static void cfq_put_request(request_queue_t *q, struct request *rq)
1938 struct cfq_data *cfqd = q->elevator->elevator_data;
1939 struct cfq_rq *crq = RQ_DATA(rq);
1942 struct cfq_queue *cfqq = crq->cfq_queue;
1943 const int rw = rq_data_dir(rq);
1945 BUG_ON(!cfqq->allocated[rw]);
1946 cfqq->allocated[rw]--;
1948 put_io_context(crq->io_context->ioc);
1950 mempool_free(crq, cfqd->crq_pool);
1951 rq->elevator_private = NULL;
1953 cfq_check_waiters(q, cfqq);
1954 cfq_put_queue(cfqq);
1959 * Allocate cfq data structures associated with this request.
1962 cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
1965 struct cfq_data *cfqd = q->elevator->elevator_data;
1966 struct task_struct *tsk = current;
1967 struct cfq_io_context *cic;
1968 const int rw = rq_data_dir(rq);
1969 pid_t key = cfq_queue_pid(tsk, rw);
1970 struct cfq_queue *cfqq;
1972 unsigned long flags;
1973 int is_sync = key != CFQ_KEY_ASYNC;
1975 might_sleep_if(gfp_mask & __GFP_WAIT);
1977 cic = cfq_get_io_context(cfqd, key, gfp_mask);
1979 spin_lock_irqsave(q->queue_lock, flags);
1984 if (!cic->cfqq[is_sync]) {
1985 cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
1989 cic->cfqq[is_sync] = cfqq;
1991 cfqq = cic->cfqq[is_sync];
1993 cfqq->allocated[rw]++;
1994 cfq_clear_cfqq_must_alloc(cfqq);
1995 cfqd->rq_starved = 0;
1996 atomic_inc(&cfqq->ref);
1997 spin_unlock_irqrestore(q->queue_lock, flags);
1999 crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
2001 RB_CLEAR(&crq->rb_node);
2004 INIT_HLIST_NODE(&crq->hash);
2005 crq->cfq_queue = cfqq;
2006 crq->io_context = cic;
2009 cfq_mark_crq_is_sync(crq);
2011 cfq_clear_crq_is_sync(crq);
2013 rq->elevator_private = crq;
2017 spin_lock_irqsave(q->queue_lock, flags);
2018 cfqq->allocated[rw]--;
2019 if (!(cfqq->allocated[0] + cfqq->allocated[1]))
2020 cfq_mark_cfqq_must_alloc(cfqq);
2021 cfq_put_queue(cfqq);
2024 put_io_context(cic->ioc);
2026 * mark us rq allocation starved. we need to kickstart the process
2027 * ourselves if there are no pending requests that can do it for us.
2028 * that would be an extremely rare OOM situation
2030 cfqd->rq_starved = 1;
2031 cfq_schedule_dispatch(cfqd);
2032 spin_unlock_irqrestore(q->queue_lock, flags);
2036 static void cfq_kick_queue(void *data)
2038 request_queue_t *q = data;
2039 struct cfq_data *cfqd = q->elevator->elevator_data;
2040 unsigned long flags;
2042 spin_lock_irqsave(q->queue_lock, flags);
2044 if (cfqd->rq_starved) {
2045 struct request_list *rl = &q->rq;
2048 * we aren't guaranteed to get a request after this, but we
2049 * have to be opportunistic
2052 if (waitqueue_active(&rl->wait[READ]))
2053 wake_up(&rl->wait[READ]);
2054 if (waitqueue_active(&rl->wait[WRITE]))
2055 wake_up(&rl->wait[WRITE]);
2060 spin_unlock_irqrestore(q->queue_lock, flags);
2064 * Timer running if the active_queue is currently idling inside its time slice
2066 static void cfq_idle_slice_timer(unsigned long data)
2068 struct cfq_data *cfqd = (struct cfq_data *) data;
2069 struct cfq_queue *cfqq;
2070 unsigned long flags;
2072 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2074 if ((cfqq = cfqd->active_queue) != NULL) {
2075 unsigned long now = jiffies;
2080 if (time_after(now, cfqq->slice_end))
2084 * only expire and reinvoke request handler, if there are
2085 * other queues with pending requests
2087 if (!cfqd->busy_queues) {
2088 cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
2089 add_timer(&cfqd->idle_slice_timer);
2094 * not expired and it has a request pending, let it dispatch
2096 if (!RB_EMPTY(&cfqq->sort_list)) {
2097 cfq_mark_cfqq_must_dispatch(cfqq);
2102 cfq_slice_expired(cfqd, 0);
2104 cfq_schedule_dispatch(cfqd);
2106 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2110 * Timer running if an idle class queue is waiting for service
2112 static void cfq_idle_class_timer(unsigned long data)
2114 struct cfq_data *cfqd = (struct cfq_data *) data;
2115 unsigned long flags, end;
2117 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2120 * race with a non-idle queue, reset timer
2122 end = cfqd->last_end_request + CFQ_IDLE_GRACE;
2123 if (!time_after_eq(jiffies, end)) {
2124 cfqd->idle_class_timer.expires = end;
2125 add_timer(&cfqd->idle_class_timer);
2127 cfq_schedule_dispatch(cfqd);
2129 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2132 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2134 del_timer_sync(&cfqd->idle_slice_timer);
2135 del_timer_sync(&cfqd->idle_class_timer);
2136 blk_sync_queue(cfqd->queue);
2139 static void cfq_put_cfqd(struct cfq_data *cfqd)
2141 if (!atomic_dec_and_test(&cfqd->ref))
2144 cfq_shutdown_timer_wq(cfqd);
2146 mempool_destroy(cfqd->crq_pool);
2147 kfree(cfqd->crq_hash);
2148 kfree(cfqd->cfq_hash);
2152 static void cfq_exit_queue(elevator_t *e)
2154 struct cfq_data *cfqd = e->elevator_data;
2155 request_queue_t *q = cfqd->queue;
2157 cfq_shutdown_timer_wq(cfqd);
2158 write_lock(&cfq_exit_lock);
2159 spin_lock_irq(q->queue_lock);
2160 if (cfqd->active_queue)
2161 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2162 while(!list_empty(&cfqd->cic_list)) {
2163 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2164 struct cfq_io_context,
2166 if (cic->cfqq[ASYNC]) {
2167 cfq_put_queue(cic->cfqq[ASYNC]);
2168 cic->cfqq[ASYNC] = NULL;
2170 if (cic->cfqq[SYNC]) {
2171 cfq_put_queue(cic->cfqq[SYNC]);
2172 cic->cfqq[SYNC] = NULL;
2175 list_del_init(&cic->queue_list);
2177 spin_unlock_irq(q->queue_lock);
2178 write_unlock(&cfq_exit_lock);
2182 static int cfq_init_queue(request_queue_t *q, elevator_t *e)
2184 struct cfq_data *cfqd;
2187 cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
2191 memset(cfqd, 0, sizeof(*cfqd));
2193 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2194 INIT_LIST_HEAD(&cfqd->rr_list[i]);
2196 INIT_LIST_HEAD(&cfqd->busy_rr);
2197 INIT_LIST_HEAD(&cfqd->cur_rr);
2198 INIT_LIST_HEAD(&cfqd->idle_rr);
2199 INIT_LIST_HEAD(&cfqd->empty_list);
2200 INIT_LIST_HEAD(&cfqd->cic_list);
2202 cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
2203 if (!cfqd->crq_hash)
2206 cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
2207 if (!cfqd->cfq_hash)
2210 cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
2211 if (!cfqd->crq_pool)
2214 for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
2215 INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
2216 for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
2217 INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
2219 e->elevator_data = cfqd;
2223 cfqd->max_queued = q->nr_requests / 4;
2224 q->nr_batching = cfq_queued;
2226 init_timer(&cfqd->idle_slice_timer);
2227 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2228 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2230 init_timer(&cfqd->idle_class_timer);
2231 cfqd->idle_class_timer.function = cfq_idle_class_timer;
2232 cfqd->idle_class_timer.data = (unsigned long) cfqd;
2234 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
2236 atomic_set(&cfqd->ref, 1);
2238 cfqd->cfq_queued = cfq_queued;
2239 cfqd->cfq_quantum = cfq_quantum;
2240 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2241 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2242 cfqd->cfq_back_max = cfq_back_max;
2243 cfqd->cfq_back_penalty = cfq_back_penalty;
2244 cfqd->cfq_slice[0] = cfq_slice_async;
2245 cfqd->cfq_slice[1] = cfq_slice_sync;
2246 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2247 cfqd->cfq_slice_idle = cfq_slice_idle;
2248 cfqd->cfq_max_depth = cfq_max_depth;
2252 kfree(cfqd->cfq_hash);
2254 kfree(cfqd->crq_hash);
2260 static void cfq_slab_kill(void)
2263 kmem_cache_destroy(crq_pool);
2265 kmem_cache_destroy(cfq_pool);
2267 kmem_cache_destroy(cfq_ioc_pool);
2270 static int __init cfq_slab_setup(void)
2272 crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
2277 cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
2282 cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
2283 sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
2294 * sysfs parts below -->
2296 struct cfq_fs_entry {
2297 struct attribute attr;
2298 ssize_t (*show)(struct cfq_data *, char *);
2299 ssize_t (*store)(struct cfq_data *, const char *, size_t);
2303 cfq_var_show(unsigned int var, char *page)
2305 return sprintf(page, "%d\n", var);
2309 cfq_var_store(unsigned int *var, const char *page, size_t count)
2311 char *p = (char *) page;
2313 *var = simple_strtoul(p, &p, 10);
2317 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2318 static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2320 unsigned int __data = __VAR; \
2322 __data = jiffies_to_msecs(__data); \
2323 return cfq_var_show(__data, (page)); \
2325 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2326 SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
2327 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2328 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2329 SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0);
2330 SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0);
2331 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2332 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2333 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2334 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2335 SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
2336 #undef SHOW_FUNCTION
2338 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2339 static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2341 unsigned int __data; \
2342 int ret = cfq_var_store(&__data, (page), count); \
2343 if (__data < (MIN)) \
2345 else if (__data > (MAX)) \
2348 *(__PTR) = msecs_to_jiffies(__data); \
2350 *(__PTR) = __data; \
2353 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2354 STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
2355 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1);
2356 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1);
2357 STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2358 STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0);
2359 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2360 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2361 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2362 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0);
2363 STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
2364 #undef STORE_FUNCTION
2366 static struct cfq_fs_entry cfq_quantum_entry = {
2367 .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
2368 .show = cfq_quantum_show,
2369 .store = cfq_quantum_store,
2371 static struct cfq_fs_entry cfq_queued_entry = {
2372 .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
2373 .show = cfq_queued_show,
2374 .store = cfq_queued_store,
2376 static struct cfq_fs_entry cfq_fifo_expire_sync_entry = {
2377 .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
2378 .show = cfq_fifo_expire_sync_show,
2379 .store = cfq_fifo_expire_sync_store,
2381 static struct cfq_fs_entry cfq_fifo_expire_async_entry = {
2382 .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
2383 .show = cfq_fifo_expire_async_show,
2384 .store = cfq_fifo_expire_async_store,
2386 static struct cfq_fs_entry cfq_back_max_entry = {
2387 .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
2388 .show = cfq_back_max_show,
2389 .store = cfq_back_max_store,
2391 static struct cfq_fs_entry cfq_back_penalty_entry = {
2392 .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
2393 .show = cfq_back_penalty_show,
2394 .store = cfq_back_penalty_store,
2396 static struct cfq_fs_entry cfq_slice_sync_entry = {
2397 .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR },
2398 .show = cfq_slice_sync_show,
2399 .store = cfq_slice_sync_store,
2401 static struct cfq_fs_entry cfq_slice_async_entry = {
2402 .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR },
2403 .show = cfq_slice_async_show,
2404 .store = cfq_slice_async_store,
2406 static struct cfq_fs_entry cfq_slice_async_rq_entry = {
2407 .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR },
2408 .show = cfq_slice_async_rq_show,
2409 .store = cfq_slice_async_rq_store,
2411 static struct cfq_fs_entry cfq_slice_idle_entry = {
2412 .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR },
2413 .show = cfq_slice_idle_show,
2414 .store = cfq_slice_idle_store,
2416 static struct cfq_fs_entry cfq_max_depth_entry = {
2417 .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR },
2418 .show = cfq_max_depth_show,
2419 .store = cfq_max_depth_store,
2422 static struct attribute *default_attrs[] = {
2423 &cfq_quantum_entry.attr,
2424 &cfq_queued_entry.attr,
2425 &cfq_fifo_expire_sync_entry.attr,
2426 &cfq_fifo_expire_async_entry.attr,
2427 &cfq_back_max_entry.attr,
2428 &cfq_back_penalty_entry.attr,
2429 &cfq_slice_sync_entry.attr,
2430 &cfq_slice_async_entry.attr,
2431 &cfq_slice_async_rq_entry.attr,
2432 &cfq_slice_idle_entry.attr,
2433 &cfq_max_depth_entry.attr,
2437 #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2440 cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
2442 elevator_t *e = container_of(kobj, elevator_t, kobj);
2443 struct cfq_fs_entry *entry = to_cfq(attr);
2448 return entry->show(e->elevator_data, page);
2452 cfq_attr_store(struct kobject *kobj, struct attribute *attr,
2453 const char *page, size_t length)
2455 elevator_t *e = container_of(kobj, elevator_t, kobj);
2456 struct cfq_fs_entry *entry = to_cfq(attr);
2461 return entry->store(e->elevator_data, page, length);
2464 static struct sysfs_ops cfq_sysfs_ops = {
2465 .show = cfq_attr_show,
2466 .store = cfq_attr_store,
2469 static struct kobj_type cfq_ktype = {
2470 .sysfs_ops = &cfq_sysfs_ops,
2471 .default_attrs = default_attrs,
2474 static struct elevator_type iosched_cfq = {
2476 .elevator_merge_fn = cfq_merge,
2477 .elevator_merged_fn = cfq_merged_request,
2478 .elevator_merge_req_fn = cfq_merged_requests,
2479 .elevator_dispatch_fn = cfq_dispatch_requests,
2480 .elevator_add_req_fn = cfq_insert_request,
2481 .elevator_activate_req_fn = cfq_activate_request,
2482 .elevator_deactivate_req_fn = cfq_deactivate_request,
2483 .elevator_queue_empty_fn = cfq_queue_empty,
2484 .elevator_completed_req_fn = cfq_completed_request,
2485 .elevator_former_req_fn = cfq_former_request,
2486 .elevator_latter_req_fn = cfq_latter_request,
2487 .elevator_set_req_fn = cfq_set_request,
2488 .elevator_put_req_fn = cfq_put_request,
2489 .elevator_may_queue_fn = cfq_may_queue,
2490 .elevator_init_fn = cfq_init_queue,
2491 .elevator_exit_fn = cfq_exit_queue,
2494 .elevator_ktype = &cfq_ktype,
2495 .elevator_name = "cfq",
2496 .elevator_owner = THIS_MODULE,
2499 static int __init cfq_init(void)
2504 * could be 0 on HZ < 1000 setups
2506 if (!cfq_slice_async)
2507 cfq_slice_async = 1;
2508 if (!cfq_slice_idle)
2511 if (cfq_slab_setup())
2514 ret = elv_register(&iosched_cfq);
2521 static void __exit cfq_exit(void)
2523 DECLARE_COMPLETION(all_gone);
2524 elv_unregister(&iosched_cfq);
2525 ioc_gone = &all_gone;
2527 if (atomic_read(&ioc_count))
2533 module_init(cfq_init);
2534 module_exit(cfq_exit);
2536 MODULE_AUTHOR("Jens Axboe");
2537 MODULE_LICENSE("GPL");
2538 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");