2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/blkdev.h>
11 #include <linux/elevator.h>
12 #include <linux/rbtree.h>
13 #include <linux/ioprio.h>
14 #include <linux/blktrace_api.h>
19 /* max queue in one round of service */
20 static const int cfq_quantum = 4;
21 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
22 /* maximum backwards seek, in KiB */
23 static const int cfq_back_max = 16 * 1024;
24 /* penalty of a backwards seek */
25 static const int cfq_back_penalty = 2;
26 static const int cfq_slice_sync = HZ / 10;
27 static int cfq_slice_async = HZ / 25;
28 static const int cfq_slice_async_rq = 2;
29 static int cfq_slice_idle = HZ / 125;
32 * offset from end of service tree
34 #define CFQ_IDLE_DELAY (HZ / 5)
37 * below this threshold, we consider thinktime immediate
39 #define CFQ_MIN_TT (2)
41 #define CFQ_SLICE_SCALE (5)
42 #define CFQ_HW_QUEUE_MIN (5)
45 ((struct cfq_io_context *) (rq)->elevator_private)
46 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
48 static struct kmem_cache *cfq_pool;
49 static struct kmem_cache *cfq_ioc_pool;
51 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
52 static struct completion *ioc_gone;
53 static DEFINE_SPINLOCK(ioc_gone_lock);
55 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
56 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
57 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
59 #define sample_valid(samples) ((samples) > 80)
62 * Most of our rbtree usage is for sorting with min extraction, so
63 * if we cache the leftmost node we don't have to walk down the tree
64 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
65 * move this into the elevator for the rq sorting as well.
71 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
74 * Per process-grouping structure
79 /* various state flags, see below */
82 struct cfq_data *cfqd;
83 /* service_tree member */
84 struct rb_node rb_node;
85 /* service_tree key */
87 /* prio tree member */
88 struct rb_node p_node;
89 /* prio tree root we belong to, if any */
90 struct rb_root *p_root;
91 /* sorted list of pending requests */
92 struct rb_root sort_list;
93 /* if fifo isn't expired, next request to serve */
94 struct request *next_rq;
95 /* requests queued in sort_list */
97 /* currently allocated requests */
99 /* fifo list of requests in sort_list */
100 struct list_head fifo;
102 unsigned long slice_end;
104 unsigned int slice_dispatch;
106 /* pending metadata requests */
108 /* number of requests that are on the dispatch list or inside driver */
111 /* io prio of this group */
112 unsigned short ioprio, org_ioprio;
113 unsigned short ioprio_class, org_ioprio_class;
119 * Per block device queue structure
122 struct request_queue *queue;
125 * rr list of queues with requests and the count of them
127 struct cfq_rb_root service_tree;
130 * Each priority tree is sorted by next_request position. These
131 * trees are used when determining if two or more queues are
132 * interleaving requests (see cfq_close_cooperator).
134 struct rb_root prio_trees[CFQ_PRIO_LISTS];
136 unsigned int busy_queues;
142 * queue-depth detection
147 int rq_in_driver_peak;
150 * idle window management
152 struct timer_list idle_slice_timer;
153 struct work_struct unplug_work;
155 struct cfq_queue *active_queue;
156 struct cfq_io_context *active_cic;
159 * async queue for each priority case
161 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
162 struct cfq_queue *async_idle_cfqq;
164 sector_t last_position;
167 * tunables, see top of file
169 unsigned int cfq_quantum;
170 unsigned int cfq_fifo_expire[2];
171 unsigned int cfq_back_penalty;
172 unsigned int cfq_back_max;
173 unsigned int cfq_slice[2];
174 unsigned int cfq_slice_async_rq;
175 unsigned int cfq_slice_idle;
176 unsigned int cfq_desktop;
178 struct list_head cic_list;
181 * Fallback dummy cfqq for extreme OOM conditions
183 struct cfq_queue oom_cfqq;
186 enum cfqq_state_flags {
187 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
188 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
189 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
190 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
191 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
192 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
193 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
194 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
195 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
196 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
199 #define CFQ_CFQQ_FNS(name) \
200 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
202 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
204 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
206 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
208 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
210 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
214 CFQ_CFQQ_FNS(wait_request);
215 CFQ_CFQQ_FNS(must_dispatch);
216 CFQ_CFQQ_FNS(must_alloc_slice);
217 CFQ_CFQQ_FNS(fifo_expire);
218 CFQ_CFQQ_FNS(idle_window);
219 CFQ_CFQQ_FNS(prio_changed);
220 CFQ_CFQQ_FNS(slice_new);
225 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
226 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
227 #define cfq_log(cfqd, fmt, args...) \
228 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
230 static void cfq_dispatch_insert(struct request_queue *, struct request *);
231 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
232 struct io_context *, gfp_t);
233 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
234 struct io_context *);
236 static inline int rq_in_driver(struct cfq_data *cfqd)
238 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
241 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
244 return cic->cfqq[!!is_sync];
247 static inline void cic_set_cfqq(struct cfq_io_context *cic,
248 struct cfq_queue *cfqq, int is_sync)
250 cic->cfqq[!!is_sync] = cfqq;
254 * We regard a request as SYNC, if it's either a read or has the SYNC bit
255 * set (in which case it could also be direct WRITE).
257 static inline int cfq_bio_sync(struct bio *bio)
259 if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO))
266 * scheduler run of queue, if there are requests pending and no one in the
267 * driver that will restart queueing
269 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
271 if (cfqd->busy_queues) {
272 cfq_log(cfqd, "schedule dispatch");
273 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
277 static int cfq_queue_empty(struct request_queue *q)
279 struct cfq_data *cfqd = q->elevator->elevator_data;
281 return !cfqd->busy_queues;
285 * Scale schedule slice based on io priority. Use the sync time slice only
286 * if a queue is marked sync and has sync io queued. A sync queue with async
287 * io only, should not get full sync slice length.
289 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
292 const int base_slice = cfqd->cfq_slice[sync];
294 WARN_ON(prio >= IOPRIO_BE_NR);
296 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
300 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
302 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
306 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
308 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
309 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
313 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
314 * isn't valid until the first request from the dispatch is activated
315 * and the slice time set.
317 static inline int cfq_slice_used(struct cfq_queue *cfqq)
319 if (cfq_cfqq_slice_new(cfqq))
321 if (time_before(jiffies, cfqq->slice_end))
328 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
329 * We choose the request that is closest to the head right now. Distance
330 * behind the head is penalized and only allowed to a certain extent.
332 static struct request *
333 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
335 sector_t last, s1, s2, d1 = 0, d2 = 0;
336 unsigned long back_max;
337 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
338 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
339 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
341 if (rq1 == NULL || rq1 == rq2)
346 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
348 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
350 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
352 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
355 s1 = blk_rq_pos(rq1);
356 s2 = blk_rq_pos(rq2);
358 last = cfqd->last_position;
361 * by definition, 1KiB is 2 sectors
363 back_max = cfqd->cfq_back_max * 2;
366 * Strict one way elevator _except_ in the case where we allow
367 * short backward seeks which are biased as twice the cost of a
368 * similar forward seek.
372 else if (s1 + back_max >= last)
373 d1 = (last - s1) * cfqd->cfq_back_penalty;
375 wrap |= CFQ_RQ1_WRAP;
379 else if (s2 + back_max >= last)
380 d2 = (last - s2) * cfqd->cfq_back_penalty;
382 wrap |= CFQ_RQ2_WRAP;
384 /* Found required data */
387 * By doing switch() on the bit mask "wrap" we avoid having to
388 * check two variables for all permutations: --> faster!
391 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
407 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
410 * Since both rqs are wrapped,
411 * start with the one that's further behind head
412 * (--> only *one* back seek required),
413 * since back seek takes more time than forward.
423 * The below is leftmost cache rbtree addon
425 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
428 root->left = rb_first(&root->rb);
431 return rb_entry(root->left, struct cfq_queue, rb_node);
436 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
442 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
446 rb_erase_init(n, &root->rb);
450 * would be nice to take fifo expire time into account as well
452 static struct request *
453 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
454 struct request *last)
456 struct rb_node *rbnext = rb_next(&last->rb_node);
457 struct rb_node *rbprev = rb_prev(&last->rb_node);
458 struct request *next = NULL, *prev = NULL;
460 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
463 prev = rb_entry_rq(rbprev);
466 next = rb_entry_rq(rbnext);
468 rbnext = rb_first(&cfqq->sort_list);
469 if (rbnext && rbnext != &last->rb_node)
470 next = rb_entry_rq(rbnext);
473 return cfq_choose_req(cfqd, next, prev);
476 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
477 struct cfq_queue *cfqq)
480 * just an approximation, should be ok.
482 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
483 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
487 * The cfqd->service_tree holds all pending cfq_queue's that have
488 * requests waiting to be processed. It is sorted in the order that
489 * we will service the queues.
491 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
494 struct rb_node **p, *parent;
495 struct cfq_queue *__cfqq;
496 unsigned long rb_key;
499 if (cfq_class_idle(cfqq)) {
500 rb_key = CFQ_IDLE_DELAY;
501 parent = rb_last(&cfqd->service_tree.rb);
502 if (parent && parent != &cfqq->rb_node) {
503 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
504 rb_key += __cfqq->rb_key;
507 } else if (!add_front) {
508 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
509 rb_key += cfqq->slice_resid;
510 cfqq->slice_resid = 0;
514 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
516 * same position, nothing more to do
518 if (rb_key == cfqq->rb_key)
521 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
526 p = &cfqd->service_tree.rb.rb_node;
531 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
534 * sort RT queues first, we always want to give
535 * preference to them. IDLE queues goes to the back.
536 * after that, sort on the next service time.
538 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
540 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
542 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
544 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
546 else if (rb_key < __cfqq->rb_key)
551 if (n == &(*p)->rb_right)
558 cfqd->service_tree.left = &cfqq->rb_node;
560 cfqq->rb_key = rb_key;
561 rb_link_node(&cfqq->rb_node, parent, p);
562 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
565 static struct cfq_queue *
566 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
567 sector_t sector, struct rb_node **ret_parent,
568 struct rb_node ***rb_link)
570 struct rb_node **p, *parent;
571 struct cfq_queue *cfqq = NULL;
579 cfqq = rb_entry(parent, struct cfq_queue, p_node);
582 * Sort strictly based on sector. Smallest to the left,
583 * largest to the right.
585 if (sector > blk_rq_pos(cfqq->next_rq))
587 else if (sector < blk_rq_pos(cfqq->next_rq))
595 *ret_parent = parent;
601 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
603 struct rb_node **p, *parent;
604 struct cfq_queue *__cfqq;
607 rb_erase(&cfqq->p_node, cfqq->p_root);
611 if (cfq_class_idle(cfqq))
616 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
617 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
618 blk_rq_pos(cfqq->next_rq), &parent, &p);
620 rb_link_node(&cfqq->p_node, parent, p);
621 rb_insert_color(&cfqq->p_node, cfqq->p_root);
627 * Update cfqq's position in the service tree.
629 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
632 * Resorting requires the cfqq to be on the RR list already.
634 if (cfq_cfqq_on_rr(cfqq)) {
635 cfq_service_tree_add(cfqd, cfqq, 0);
636 cfq_prio_tree_add(cfqd, cfqq);
641 * add to busy list of queues for service, trying to be fair in ordering
642 * the pending list according to last request service
644 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
646 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
647 BUG_ON(cfq_cfqq_on_rr(cfqq));
648 cfq_mark_cfqq_on_rr(cfqq);
651 cfq_resort_rr_list(cfqd, cfqq);
655 * Called when the cfqq no longer has requests pending, remove it from
658 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
660 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
661 BUG_ON(!cfq_cfqq_on_rr(cfqq));
662 cfq_clear_cfqq_on_rr(cfqq);
664 if (!RB_EMPTY_NODE(&cfqq->rb_node))
665 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
667 rb_erase(&cfqq->p_node, cfqq->p_root);
671 BUG_ON(!cfqd->busy_queues);
676 * rb tree support functions
678 static void cfq_del_rq_rb(struct request *rq)
680 struct cfq_queue *cfqq = RQ_CFQQ(rq);
681 struct cfq_data *cfqd = cfqq->cfqd;
682 const int sync = rq_is_sync(rq);
684 BUG_ON(!cfqq->queued[sync]);
685 cfqq->queued[sync]--;
687 elv_rb_del(&cfqq->sort_list, rq);
689 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
690 cfq_del_cfqq_rr(cfqd, cfqq);
693 static void cfq_add_rq_rb(struct request *rq)
695 struct cfq_queue *cfqq = RQ_CFQQ(rq);
696 struct cfq_data *cfqd = cfqq->cfqd;
697 struct request *__alias, *prev;
699 cfqq->queued[rq_is_sync(rq)]++;
702 * looks a little odd, but the first insert might return an alias.
703 * if that happens, put the alias on the dispatch list
705 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
706 cfq_dispatch_insert(cfqd->queue, __alias);
708 if (!cfq_cfqq_on_rr(cfqq))
709 cfq_add_cfqq_rr(cfqd, cfqq);
712 * check if this request is a better next-serve candidate
714 prev = cfqq->next_rq;
715 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
718 * adjust priority tree position, if ->next_rq changes
720 if (prev != cfqq->next_rq)
721 cfq_prio_tree_add(cfqd, cfqq);
723 BUG_ON(!cfqq->next_rq);
726 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
728 elv_rb_del(&cfqq->sort_list, rq);
729 cfqq->queued[rq_is_sync(rq)]--;
733 static struct request *
734 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
736 struct task_struct *tsk = current;
737 struct cfq_io_context *cic;
738 struct cfq_queue *cfqq;
740 cic = cfq_cic_lookup(cfqd, tsk->io_context);
744 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
746 sector_t sector = bio->bi_sector + bio_sectors(bio);
748 return elv_rb_find(&cfqq->sort_list, sector);
754 static void cfq_activate_request(struct request_queue *q, struct request *rq)
756 struct cfq_data *cfqd = q->elevator->elevator_data;
758 cfqd->rq_in_driver[rq_is_sync(rq)]++;
759 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
762 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
765 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
767 struct cfq_data *cfqd = q->elevator->elevator_data;
768 const int sync = rq_is_sync(rq);
770 WARN_ON(!cfqd->rq_in_driver[sync]);
771 cfqd->rq_in_driver[sync]--;
772 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
776 static void cfq_remove_request(struct request *rq)
778 struct cfq_queue *cfqq = RQ_CFQQ(rq);
780 if (cfqq->next_rq == rq)
781 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
783 list_del_init(&rq->queuelist);
786 cfqq->cfqd->rq_queued--;
787 if (rq_is_meta(rq)) {
788 WARN_ON(!cfqq->meta_pending);
789 cfqq->meta_pending--;
793 static int cfq_merge(struct request_queue *q, struct request **req,
796 struct cfq_data *cfqd = q->elevator->elevator_data;
797 struct request *__rq;
799 __rq = cfq_find_rq_fmerge(cfqd, bio);
800 if (__rq && elv_rq_merge_ok(__rq, bio)) {
802 return ELEVATOR_FRONT_MERGE;
805 return ELEVATOR_NO_MERGE;
808 static void cfq_merged_request(struct request_queue *q, struct request *req,
811 if (type == ELEVATOR_FRONT_MERGE) {
812 struct cfq_queue *cfqq = RQ_CFQQ(req);
814 cfq_reposition_rq_rb(cfqq, req);
819 cfq_merged_requests(struct request_queue *q, struct request *rq,
820 struct request *next)
823 * reposition in fifo if next is older than rq
825 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
826 time_before(next->start_time, rq->start_time))
827 list_move(&rq->queuelist, &next->queuelist);
829 cfq_remove_request(next);
832 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
835 struct cfq_data *cfqd = q->elevator->elevator_data;
836 struct cfq_io_context *cic;
837 struct cfq_queue *cfqq;
840 * Disallow merge of a sync bio into an async request.
842 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
846 * Lookup the cfqq that this bio will be queued with. Allow
847 * merge only if rq is queued there.
849 cic = cfq_cic_lookup(cfqd, current->io_context);
853 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
854 if (cfqq == RQ_CFQQ(rq))
860 static void __cfq_set_active_queue(struct cfq_data *cfqd,
861 struct cfq_queue *cfqq)
864 cfq_log_cfqq(cfqd, cfqq, "set_active");
866 cfqq->slice_dispatch = 0;
868 cfq_clear_cfqq_wait_request(cfqq);
869 cfq_clear_cfqq_must_dispatch(cfqq);
870 cfq_clear_cfqq_must_alloc_slice(cfqq);
871 cfq_clear_cfqq_fifo_expire(cfqq);
872 cfq_mark_cfqq_slice_new(cfqq);
874 del_timer(&cfqd->idle_slice_timer);
877 cfqd->active_queue = cfqq;
881 * current cfqq expired its slice (or was too idle), select new one
884 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
887 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
889 if (cfq_cfqq_wait_request(cfqq))
890 del_timer(&cfqd->idle_slice_timer);
892 cfq_clear_cfqq_wait_request(cfqq);
895 * store what was left of this slice, if the queue idled/timed out
897 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
898 cfqq->slice_resid = cfqq->slice_end - jiffies;
899 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
902 cfq_resort_rr_list(cfqd, cfqq);
904 if (cfqq == cfqd->active_queue)
905 cfqd->active_queue = NULL;
907 if (cfqd->active_cic) {
908 put_io_context(cfqd->active_cic->ioc);
909 cfqd->active_cic = NULL;
913 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
915 struct cfq_queue *cfqq = cfqd->active_queue;
918 __cfq_slice_expired(cfqd, cfqq, timed_out);
922 * Get next queue for service. Unless we have a queue preemption,
923 * we'll simply select the first cfqq in the service tree.
925 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
927 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
930 return cfq_rb_first(&cfqd->service_tree);
934 * Get and set a new active queue for service.
936 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
937 struct cfq_queue *cfqq)
940 cfqq = cfq_get_next_queue(cfqd);
942 cfq_clear_cfqq_coop(cfqq);
945 __cfq_set_active_queue(cfqd, cfqq);
949 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
952 if (blk_rq_pos(rq) >= cfqd->last_position)
953 return blk_rq_pos(rq) - cfqd->last_position;
955 return cfqd->last_position - blk_rq_pos(rq);
958 #define CIC_SEEK_THR 8 * 1024
959 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
961 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
963 struct cfq_io_context *cic = cfqd->active_cic;
964 sector_t sdist = cic->seek_mean;
966 if (!sample_valid(cic->seek_samples))
967 sdist = CIC_SEEK_THR;
969 return cfq_dist_from_last(cfqd, rq) <= sdist;
972 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
973 struct cfq_queue *cur_cfqq)
975 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
976 struct rb_node *parent, *node;
977 struct cfq_queue *__cfqq;
978 sector_t sector = cfqd->last_position;
980 if (RB_EMPTY_ROOT(root))
984 * First, if we find a request starting at the end of the last
985 * request, choose it.
987 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
992 * If the exact sector wasn't found, the parent of the NULL leaf
993 * will contain the closest sector.
995 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
996 if (cfq_rq_close(cfqd, __cfqq->next_rq))
999 if (blk_rq_pos(__cfqq->next_rq) < sector)
1000 node = rb_next(&__cfqq->p_node);
1002 node = rb_prev(&__cfqq->p_node);
1006 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1007 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1015 * cur_cfqq - passed in so that we don't decide that the current queue is
1016 * closely cooperating with itself.
1018 * So, basically we're assuming that that cur_cfqq has dispatched at least
1019 * one request, and that cfqd->last_position reflects a position on the disk
1020 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1023 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1024 struct cfq_queue *cur_cfqq,
1027 struct cfq_queue *cfqq;
1030 * A valid cfq_io_context is necessary to compare requests against
1031 * the seek_mean of the current cfqq.
1033 if (!cfqd->active_cic)
1037 * We should notice if some of the queues are cooperating, eg
1038 * working closely on the same area of the disk. In that case,
1039 * we can group them together and don't waste time idling.
1041 cfqq = cfqq_close(cfqd, cur_cfqq);
1045 if (cfq_cfqq_coop(cfqq))
1049 cfq_mark_cfqq_coop(cfqq);
1053 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1055 struct cfq_queue *cfqq = cfqd->active_queue;
1056 struct cfq_io_context *cic;
1060 * SSD device without seek penalty, disable idling. But only do so
1061 * for devices that support queuing, otherwise we still have a problem
1062 * with sync vs async workloads.
1064 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1067 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1068 WARN_ON(cfq_cfqq_slice_new(cfqq));
1071 * idle is disabled, either manually or by past process history
1073 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1077 * still requests with the driver, don't idle
1079 if (rq_in_driver(cfqd))
1083 * task has exited, don't wait
1085 cic = cfqd->active_cic;
1086 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1089 cfq_mark_cfqq_wait_request(cfqq);
1092 * we don't want to idle for seeks, but we do want to allow
1093 * fair distribution of slice time for a process doing back-to-back
1094 * seeks. so allow a little bit of time for him to submit a new rq
1096 sl = cfqd->cfq_slice_idle;
1097 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1098 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1100 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1101 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1105 * Move request from internal lists to the request queue dispatch list.
1107 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1109 struct cfq_data *cfqd = q->elevator->elevator_data;
1110 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1112 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1114 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1115 cfq_remove_request(rq);
1117 elv_dispatch_sort(q, rq);
1119 if (cfq_cfqq_sync(cfqq))
1120 cfqd->sync_flight++;
1124 * return expired entry, or NULL to just start from scratch in rbtree
1126 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1128 struct cfq_data *cfqd = cfqq->cfqd;
1132 if (cfq_cfqq_fifo_expire(cfqq))
1135 cfq_mark_cfqq_fifo_expire(cfqq);
1137 if (list_empty(&cfqq->fifo))
1140 fifo = cfq_cfqq_sync(cfqq);
1141 rq = rq_entry_fifo(cfqq->fifo.next);
1143 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
1146 cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
1151 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1153 const int base_rq = cfqd->cfq_slice_async_rq;
1155 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1157 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1161 * Select a queue for service. If we have a current active queue,
1162 * check whether to continue servicing it, or retrieve and set a new one.
1164 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1166 struct cfq_queue *cfqq, *new_cfqq = NULL;
1168 cfqq = cfqd->active_queue;
1173 * The active queue has run out of time, expire it and select new.
1175 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1179 * The active queue has requests and isn't expired, allow it to
1182 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1186 * If another queue has a request waiting within our mean seek
1187 * distance, let it run. The expire code will check for close
1188 * cooperators and put the close queue at the front of the service
1191 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1196 * No requests pending. If the active queue still has requests in
1197 * flight or is idling for a new request, allow either of these
1198 * conditions to happen (or time out) before selecting a new queue.
1200 if (timer_pending(&cfqd->idle_slice_timer) ||
1201 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1207 cfq_slice_expired(cfqd, 0);
1209 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1214 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1218 while (cfqq->next_rq) {
1219 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1223 BUG_ON(!list_empty(&cfqq->fifo));
1228 * Drain our current requests. Used for barriers and when switching
1229 * io schedulers on-the-fly.
1231 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1233 struct cfq_queue *cfqq;
1236 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1237 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1239 cfq_slice_expired(cfqd, 0);
1241 BUG_ON(cfqd->busy_queues);
1243 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1248 * Dispatch a request from cfqq, moving them to the request queue
1251 static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1255 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1258 * follow expired path, else get first next available
1260 rq = cfq_check_fifo(cfqq);
1265 * insert request into driver dispatch list
1267 cfq_dispatch_insert(cfqd->queue, rq);
1269 if (!cfqd->active_cic) {
1270 struct cfq_io_context *cic = RQ_CIC(rq);
1272 atomic_long_inc(&cic->ioc->refcount);
1273 cfqd->active_cic = cic;
1278 * Find the cfqq that we need to service and move a request from that to the
1281 static int cfq_dispatch_requests(struct request_queue *q, int force)
1283 struct cfq_data *cfqd = q->elevator->elevator_data;
1284 struct cfq_queue *cfqq;
1285 unsigned int max_dispatch;
1287 if (!cfqd->busy_queues)
1290 if (unlikely(force))
1291 return cfq_forced_dispatch(cfqd);
1293 cfqq = cfq_select_queue(cfqd);
1298 * Drain async requests before we start sync IO
1300 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1304 * If this is an async queue and we have sync IO in flight, let it wait
1306 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1309 max_dispatch = cfqd->cfq_quantum;
1310 if (cfq_class_idle(cfqq))
1314 * Does this cfqq already have too much IO in flight?
1316 if (cfqq->dispatched >= max_dispatch) {
1318 * idle queue must always only have a single IO in flight
1320 if (cfq_class_idle(cfqq))
1324 * We have other queues, don't allow more IO from this one
1326 if (cfqd->busy_queues > 1)
1330 * we are the only queue, allow up to 4 times of 'quantum'
1332 if (cfqq->dispatched >= 4 * max_dispatch)
1337 * Dispatch a request from this cfqq
1339 cfq_dispatch_request(cfqd, cfqq);
1340 cfqq->slice_dispatch++;
1341 cfq_clear_cfqq_must_dispatch(cfqq);
1344 * expire an async queue immediately if it has used up its slice. idle
1345 * queue always expire after 1 dispatch round.
1347 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1348 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1349 cfq_class_idle(cfqq))) {
1350 cfqq->slice_end = jiffies + 1;
1351 cfq_slice_expired(cfqd, 0);
1354 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
1359 * task holds one reference to the queue, dropped when task exits. each rq
1360 * in-flight on this queue also holds a reference, dropped when rq is freed.
1362 * queue lock must be held here.
1364 static void cfq_put_queue(struct cfq_queue *cfqq)
1366 struct cfq_data *cfqd = cfqq->cfqd;
1368 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1370 if (!atomic_dec_and_test(&cfqq->ref))
1373 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1374 BUG_ON(rb_first(&cfqq->sort_list));
1375 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1376 BUG_ON(cfq_cfqq_on_rr(cfqq));
1378 if (unlikely(cfqd->active_queue == cfqq)) {
1379 __cfq_slice_expired(cfqd, cfqq, 0);
1380 cfq_schedule_dispatch(cfqd);
1383 kmem_cache_free(cfq_pool, cfqq);
1387 * Must always be called with the rcu_read_lock() held
1390 __call_for_each_cic(struct io_context *ioc,
1391 void (*func)(struct io_context *, struct cfq_io_context *))
1393 struct cfq_io_context *cic;
1394 struct hlist_node *n;
1396 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1401 * Call func for each cic attached to this ioc.
1404 call_for_each_cic(struct io_context *ioc,
1405 void (*func)(struct io_context *, struct cfq_io_context *))
1408 __call_for_each_cic(ioc, func);
1412 static void cfq_cic_free_rcu(struct rcu_head *head)
1414 struct cfq_io_context *cic;
1416 cic = container_of(head, struct cfq_io_context, rcu_head);
1418 kmem_cache_free(cfq_ioc_pool, cic);
1419 elv_ioc_count_dec(cfq_ioc_count);
1423 * CFQ scheduler is exiting, grab exit lock and check
1424 * the pending io context count. If it hits zero,
1425 * complete ioc_gone and set it back to NULL
1427 spin_lock(&ioc_gone_lock);
1428 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
1432 spin_unlock(&ioc_gone_lock);
1436 static void cfq_cic_free(struct cfq_io_context *cic)
1438 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1441 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1443 unsigned long flags;
1445 BUG_ON(!cic->dead_key);
1447 spin_lock_irqsave(&ioc->lock, flags);
1448 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1449 hlist_del_rcu(&cic->cic_list);
1450 spin_unlock_irqrestore(&ioc->lock, flags);
1456 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1457 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1458 * and ->trim() which is called with the task lock held
1460 static void cfq_free_io_context(struct io_context *ioc)
1463 * ioc->refcount is zero here, or we are called from elv_unregister(),
1464 * so no more cic's are allowed to be linked into this ioc. So it
1465 * should be ok to iterate over the known list, we will see all cic's
1466 * since no new ones are added.
1468 __call_for_each_cic(ioc, cic_free_func);
1471 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1473 if (unlikely(cfqq == cfqd->active_queue)) {
1474 __cfq_slice_expired(cfqd, cfqq, 0);
1475 cfq_schedule_dispatch(cfqd);
1478 cfq_put_queue(cfqq);
1481 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1482 struct cfq_io_context *cic)
1484 struct io_context *ioc = cic->ioc;
1486 list_del_init(&cic->queue_list);
1489 * Make sure key == NULL is seen for dead queues
1492 cic->dead_key = (unsigned long) cic->key;
1495 if (ioc->ioc_data == cic)
1496 rcu_assign_pointer(ioc->ioc_data, NULL);
1498 if (cic->cfqq[BLK_RW_ASYNC]) {
1499 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1500 cic->cfqq[BLK_RW_ASYNC] = NULL;
1503 if (cic->cfqq[BLK_RW_SYNC]) {
1504 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1505 cic->cfqq[BLK_RW_SYNC] = NULL;
1509 static void cfq_exit_single_io_context(struct io_context *ioc,
1510 struct cfq_io_context *cic)
1512 struct cfq_data *cfqd = cic->key;
1515 struct request_queue *q = cfqd->queue;
1516 unsigned long flags;
1518 spin_lock_irqsave(q->queue_lock, flags);
1521 * Ensure we get a fresh copy of the ->key to prevent
1522 * race between exiting task and queue
1524 smp_read_barrier_depends();
1526 __cfq_exit_single_io_context(cfqd, cic);
1528 spin_unlock_irqrestore(q->queue_lock, flags);
1533 * The process that ioc belongs to has exited, we need to clean up
1534 * and put the internal structures we have that belongs to that process.
1536 static void cfq_exit_io_context(struct io_context *ioc)
1538 call_for_each_cic(ioc, cfq_exit_single_io_context);
1541 static struct cfq_io_context *
1542 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1544 struct cfq_io_context *cic;
1546 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1549 cic->last_end_request = jiffies;
1550 INIT_LIST_HEAD(&cic->queue_list);
1551 INIT_HLIST_NODE(&cic->cic_list);
1552 cic->dtor = cfq_free_io_context;
1553 cic->exit = cfq_exit_io_context;
1554 elv_ioc_count_inc(cfq_ioc_count);
1560 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1562 struct task_struct *tsk = current;
1565 if (!cfq_cfqq_prio_changed(cfqq))
1568 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1569 switch (ioprio_class) {
1571 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1572 case IOPRIO_CLASS_NONE:
1574 * no prio set, inherit CPU scheduling settings
1576 cfqq->ioprio = task_nice_ioprio(tsk);
1577 cfqq->ioprio_class = task_nice_ioclass(tsk);
1579 case IOPRIO_CLASS_RT:
1580 cfqq->ioprio = task_ioprio(ioc);
1581 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1583 case IOPRIO_CLASS_BE:
1584 cfqq->ioprio = task_ioprio(ioc);
1585 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1587 case IOPRIO_CLASS_IDLE:
1588 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1590 cfq_clear_cfqq_idle_window(cfqq);
1595 * keep track of original prio settings in case we have to temporarily
1596 * elevate the priority of this queue
1598 cfqq->org_ioprio = cfqq->ioprio;
1599 cfqq->org_ioprio_class = cfqq->ioprio_class;
1600 cfq_clear_cfqq_prio_changed(cfqq);
1603 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1605 struct cfq_data *cfqd = cic->key;
1606 struct cfq_queue *cfqq;
1607 unsigned long flags;
1609 if (unlikely(!cfqd))
1612 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1614 cfqq = cic->cfqq[BLK_RW_ASYNC];
1616 struct cfq_queue *new_cfqq;
1617 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1620 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1621 cfq_put_queue(cfqq);
1625 cfqq = cic->cfqq[BLK_RW_SYNC];
1627 cfq_mark_cfqq_prio_changed(cfqq);
1629 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1632 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1634 call_for_each_cic(ioc, changed_ioprio);
1635 ioc->ioprio_changed = 0;
1638 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1639 pid_t pid, int is_sync)
1641 RB_CLEAR_NODE(&cfqq->rb_node);
1642 RB_CLEAR_NODE(&cfqq->p_node);
1643 INIT_LIST_HEAD(&cfqq->fifo);
1645 atomic_set(&cfqq->ref, 0);
1648 cfq_mark_cfqq_prio_changed(cfqq);
1651 if (!cfq_class_idle(cfqq))
1652 cfq_mark_cfqq_idle_window(cfqq);
1653 cfq_mark_cfqq_sync(cfqq);
1658 static struct cfq_queue *
1659 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1660 struct io_context *ioc, gfp_t gfp_mask)
1662 struct cfq_queue *cfqq, *new_cfqq = NULL;
1663 struct cfq_io_context *cic;
1666 cic = cfq_cic_lookup(cfqd, ioc);
1667 /* cic always exists here */
1668 cfqq = cic_to_cfqq(cic, is_sync);
1671 * Always try a new alloc if we fell back to the OOM cfqq
1672 * originally, since it should just be a temporary situation.
1674 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1679 } else if (gfp_mask & __GFP_WAIT) {
1680 spin_unlock_irq(cfqd->queue->queue_lock);
1681 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1682 gfp_mask | __GFP_ZERO,
1684 spin_lock_irq(cfqd->queue->queue_lock);
1688 cfqq = kmem_cache_alloc_node(cfq_pool,
1689 gfp_mask | __GFP_ZERO,
1694 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1695 cfq_init_prio_data(cfqq, ioc);
1696 cfq_log_cfqq(cfqd, cfqq, "alloced");
1698 cfqq = &cfqd->oom_cfqq;
1702 kmem_cache_free(cfq_pool, new_cfqq);
1707 static struct cfq_queue **
1708 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1710 switch (ioprio_class) {
1711 case IOPRIO_CLASS_RT:
1712 return &cfqd->async_cfqq[0][ioprio];
1713 case IOPRIO_CLASS_BE:
1714 return &cfqd->async_cfqq[1][ioprio];
1715 case IOPRIO_CLASS_IDLE:
1716 return &cfqd->async_idle_cfqq;
1722 static struct cfq_queue *
1723 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1726 const int ioprio = task_ioprio(ioc);
1727 const int ioprio_class = task_ioprio_class(ioc);
1728 struct cfq_queue **async_cfqq = NULL;
1729 struct cfq_queue *cfqq = NULL;
1732 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1737 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1740 * pin the queue now that it's allocated, scheduler exit will prune it
1742 if (!is_sync && !(*async_cfqq)) {
1743 atomic_inc(&cfqq->ref);
1747 atomic_inc(&cfqq->ref);
1752 * We drop cfq io contexts lazily, so we may find a dead one.
1755 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1756 struct cfq_io_context *cic)
1758 unsigned long flags;
1760 WARN_ON(!list_empty(&cic->queue_list));
1762 spin_lock_irqsave(&ioc->lock, flags);
1764 BUG_ON(ioc->ioc_data == cic);
1766 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1767 hlist_del_rcu(&cic->cic_list);
1768 spin_unlock_irqrestore(&ioc->lock, flags);
1773 static struct cfq_io_context *
1774 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1776 struct cfq_io_context *cic;
1777 unsigned long flags;
1786 * we maintain a last-hit cache, to avoid browsing over the tree
1788 cic = rcu_dereference(ioc->ioc_data);
1789 if (cic && cic->key == cfqd) {
1795 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1799 /* ->key must be copied to avoid race with cfq_exit_queue() */
1802 cfq_drop_dead_cic(cfqd, ioc, cic);
1807 spin_lock_irqsave(&ioc->lock, flags);
1808 rcu_assign_pointer(ioc->ioc_data, cic);
1809 spin_unlock_irqrestore(&ioc->lock, flags);
1817 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1818 * the process specific cfq io context when entered from the block layer.
1819 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1821 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1822 struct cfq_io_context *cic, gfp_t gfp_mask)
1824 unsigned long flags;
1827 ret = radix_tree_preload(gfp_mask);
1832 spin_lock_irqsave(&ioc->lock, flags);
1833 ret = radix_tree_insert(&ioc->radix_root,
1834 (unsigned long) cfqd, cic);
1836 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1837 spin_unlock_irqrestore(&ioc->lock, flags);
1839 radix_tree_preload_end();
1842 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1843 list_add(&cic->queue_list, &cfqd->cic_list);
1844 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1849 printk(KERN_ERR "cfq: cic link failed!\n");
1855 * Setup general io context and cfq io context. There can be several cfq
1856 * io contexts per general io context, if this process is doing io to more
1857 * than one device managed by cfq.
1859 static struct cfq_io_context *
1860 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1862 struct io_context *ioc = NULL;
1863 struct cfq_io_context *cic;
1865 might_sleep_if(gfp_mask & __GFP_WAIT);
1867 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1871 cic = cfq_cic_lookup(cfqd, ioc);
1875 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1879 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1883 smp_read_barrier_depends();
1884 if (unlikely(ioc->ioprio_changed))
1885 cfq_ioc_set_ioprio(ioc);
1891 put_io_context(ioc);
1896 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1898 unsigned long elapsed = jiffies - cic->last_end_request;
1899 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1901 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1902 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1903 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1907 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1913 if (!cic->last_request_pos)
1915 else if (cic->last_request_pos < blk_rq_pos(rq))
1916 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1918 sdist = cic->last_request_pos - blk_rq_pos(rq);
1921 * Don't allow the seek distance to get too large from the
1922 * odd fragment, pagein, etc
1924 if (cic->seek_samples <= 60) /* second&third seek */
1925 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1927 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1929 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1930 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1931 total = cic->seek_total + (cic->seek_samples/2);
1932 do_div(total, cic->seek_samples);
1933 cic->seek_mean = (sector_t)total;
1937 * Disable idle window if the process thinks too long or seeks so much that
1941 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1942 struct cfq_io_context *cic)
1944 int old_idle, enable_idle;
1947 * Don't idle for async or idle io prio class
1949 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1952 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1954 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1955 (!cfqd->cfq_desktop && cfqd->hw_tag && CIC_SEEKY(cic)))
1957 else if (sample_valid(cic->ttime_samples)) {
1958 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1964 if (old_idle != enable_idle) {
1965 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
1967 cfq_mark_cfqq_idle_window(cfqq);
1969 cfq_clear_cfqq_idle_window(cfqq);
1974 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1975 * no or if we aren't sure, a 1 will cause a preempt.
1978 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1981 struct cfq_queue *cfqq;
1983 cfqq = cfqd->active_queue;
1987 if (cfq_slice_used(cfqq))
1990 if (cfq_class_idle(new_cfqq))
1993 if (cfq_class_idle(cfqq))
1997 * if the new request is sync, but the currently running queue is
1998 * not, let the sync request have priority.
2000 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2004 * So both queues are sync. Let the new request get disk time if
2005 * it's a metadata request and the current queue is doing regular IO.
2007 if (rq_is_meta(rq) && !cfqq->meta_pending)
2011 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2013 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2016 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2020 * if this request is as-good as one we would expect from the
2021 * current cfqq, let it preempt
2023 if (cfq_rq_close(cfqd, rq))
2030 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2031 * let it have half of its nominal slice.
2033 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2035 cfq_log_cfqq(cfqd, cfqq, "preempt");
2036 cfq_slice_expired(cfqd, 1);
2039 * Put the new queue at the front of the of the current list,
2040 * so we know that it will be selected next.
2042 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2044 cfq_service_tree_add(cfqd, cfqq, 1);
2046 cfqq->slice_end = 0;
2047 cfq_mark_cfqq_slice_new(cfqq);
2051 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2052 * something we should do about it
2055 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2058 struct cfq_io_context *cic = RQ_CIC(rq);
2062 cfqq->meta_pending++;
2064 cfq_update_io_thinktime(cfqd, cic);
2065 cfq_update_io_seektime(cfqd, cic, rq);
2066 cfq_update_idle_window(cfqd, cfqq, cic);
2068 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2070 if (cfqq == cfqd->active_queue) {
2072 * Remember that we saw a request from this process, but
2073 * don't start queuing just yet. Otherwise we risk seeing lots
2074 * of tiny requests, because we disrupt the normal plugging
2075 * and merging. If the request is already larger than a single
2076 * page, let it rip immediately. For that case we assume that
2077 * merging is already done. Ditto for a busy system that
2078 * has other work pending, don't risk delaying until the
2079 * idle timer unplug to continue working.
2081 if (cfq_cfqq_wait_request(cfqq)) {
2082 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2083 cfqd->busy_queues > 1) {
2084 del_timer(&cfqd->idle_slice_timer);
2085 __blk_run_queue(cfqd->queue);
2087 cfq_mark_cfqq_must_dispatch(cfqq);
2089 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2091 * not the active queue - expire current slice if it is
2092 * idle and has expired it's mean thinktime or this new queue
2093 * has some old slice time left and is of higher priority or
2094 * this new queue is RT and the current one is BE
2096 cfq_preempt_queue(cfqd, cfqq);
2097 __blk_run_queue(cfqd->queue);
2101 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2103 struct cfq_data *cfqd = q->elevator->elevator_data;
2104 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2106 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2107 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2111 list_add_tail(&rq->queuelist, &cfqq->fifo);
2113 cfq_rq_enqueued(cfqd, cfqq, rq);
2117 * Update hw_tag based on peak queue depth over 50 samples under
2120 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2122 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2123 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
2125 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2126 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2129 if (cfqd->hw_tag_samples++ < 50)
2132 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2137 cfqd->hw_tag_samples = 0;
2138 cfqd->rq_in_driver_peak = 0;
2141 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2143 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2144 struct cfq_data *cfqd = cfqq->cfqd;
2145 const int sync = rq_is_sync(rq);
2149 cfq_log_cfqq(cfqd, cfqq, "complete");
2151 cfq_update_hw_tag(cfqd);
2153 WARN_ON(!cfqd->rq_in_driver[sync]);
2154 WARN_ON(!cfqq->dispatched);
2155 cfqd->rq_in_driver[sync]--;
2158 if (cfq_cfqq_sync(cfqq))
2159 cfqd->sync_flight--;
2162 RQ_CIC(rq)->last_end_request = now;
2165 * If this is the active queue, check if it needs to be expired,
2166 * or if we want to idle in case it has no pending requests.
2168 if (cfqd->active_queue == cfqq) {
2169 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2171 if (cfq_cfqq_slice_new(cfqq)) {
2172 cfq_set_prio_slice(cfqd, cfqq);
2173 cfq_clear_cfqq_slice_new(cfqq);
2176 * If there are no requests waiting in this queue, and
2177 * there are other queues ready to issue requests, AND
2178 * those other queues are issuing requests within our
2179 * mean seek distance, give them a chance to run instead
2182 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2183 cfq_slice_expired(cfqd, 1);
2184 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2185 sync && !rq_noidle(rq))
2186 cfq_arm_slice_timer(cfqd);
2189 if (!rq_in_driver(cfqd))
2190 cfq_schedule_dispatch(cfqd);
2194 * we temporarily boost lower priority queues if they are holding fs exclusive
2195 * resources. they are boosted to normal prio (CLASS_BE/4)
2197 static void cfq_prio_boost(struct cfq_queue *cfqq)
2199 if (has_fs_excl()) {
2201 * boost idle prio on transactions that would lock out other
2202 * users of the filesystem
2204 if (cfq_class_idle(cfqq))
2205 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2206 if (cfqq->ioprio > IOPRIO_NORM)
2207 cfqq->ioprio = IOPRIO_NORM;
2210 * check if we need to unboost the queue
2212 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2213 cfqq->ioprio_class = cfqq->org_ioprio_class;
2214 if (cfqq->ioprio != cfqq->org_ioprio)
2215 cfqq->ioprio = cfqq->org_ioprio;
2219 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2221 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
2222 cfq_mark_cfqq_must_alloc_slice(cfqq);
2223 return ELV_MQUEUE_MUST;
2226 return ELV_MQUEUE_MAY;
2229 static int cfq_may_queue(struct request_queue *q, int rw)
2231 struct cfq_data *cfqd = q->elevator->elevator_data;
2232 struct task_struct *tsk = current;
2233 struct cfq_io_context *cic;
2234 struct cfq_queue *cfqq;
2237 * don't force setup of a queue from here, as a call to may_queue
2238 * does not necessarily imply that a request actually will be queued.
2239 * so just lookup a possibly existing queue, or return 'may queue'
2242 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2244 return ELV_MQUEUE_MAY;
2246 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2248 cfq_init_prio_data(cfqq, cic->ioc);
2249 cfq_prio_boost(cfqq);
2251 return __cfq_may_queue(cfqq);
2254 return ELV_MQUEUE_MAY;
2258 * queue lock held here
2260 static void cfq_put_request(struct request *rq)
2262 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2265 const int rw = rq_data_dir(rq);
2267 BUG_ON(!cfqq->allocated[rw]);
2268 cfqq->allocated[rw]--;
2270 put_io_context(RQ_CIC(rq)->ioc);
2272 rq->elevator_private = NULL;
2273 rq->elevator_private2 = NULL;
2275 cfq_put_queue(cfqq);
2280 * Allocate cfq data structures associated with this request.
2283 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2285 struct cfq_data *cfqd = q->elevator->elevator_data;
2286 struct cfq_io_context *cic;
2287 const int rw = rq_data_dir(rq);
2288 const int is_sync = rq_is_sync(rq);
2289 struct cfq_queue *cfqq;
2290 unsigned long flags;
2292 might_sleep_if(gfp_mask & __GFP_WAIT);
2294 cic = cfq_get_io_context(cfqd, gfp_mask);
2296 spin_lock_irqsave(q->queue_lock, flags);
2301 cfqq = cic_to_cfqq(cic, is_sync);
2302 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2303 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2304 cic_set_cfqq(cic, cfqq, is_sync);
2307 cfqq->allocated[rw]++;
2308 atomic_inc(&cfqq->ref);
2310 spin_unlock_irqrestore(q->queue_lock, flags);
2312 rq->elevator_private = cic;
2313 rq->elevator_private2 = cfqq;
2318 put_io_context(cic->ioc);
2320 cfq_schedule_dispatch(cfqd);
2321 spin_unlock_irqrestore(q->queue_lock, flags);
2322 cfq_log(cfqd, "set_request fail");
2326 static void cfq_kick_queue(struct work_struct *work)
2328 struct cfq_data *cfqd =
2329 container_of(work, struct cfq_data, unplug_work);
2330 struct request_queue *q = cfqd->queue;
2332 spin_lock_irq(q->queue_lock);
2333 __blk_run_queue(cfqd->queue);
2334 spin_unlock_irq(q->queue_lock);
2338 * Timer running if the active_queue is currently idling inside its time slice
2340 static void cfq_idle_slice_timer(unsigned long data)
2342 struct cfq_data *cfqd = (struct cfq_data *) data;
2343 struct cfq_queue *cfqq;
2344 unsigned long flags;
2347 cfq_log(cfqd, "idle timer fired");
2349 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2351 cfqq = cfqd->active_queue;
2356 * We saw a request before the queue expired, let it through
2358 if (cfq_cfqq_must_dispatch(cfqq))
2364 if (cfq_slice_used(cfqq))
2368 * only expire and reinvoke request handler, if there are
2369 * other queues with pending requests
2371 if (!cfqd->busy_queues)
2375 * not expired and it has a request pending, let it dispatch
2377 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2381 cfq_slice_expired(cfqd, timed_out);
2383 cfq_schedule_dispatch(cfqd);
2385 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2388 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2390 del_timer_sync(&cfqd->idle_slice_timer);
2391 cancel_work_sync(&cfqd->unplug_work);
2394 static void cfq_put_async_queues(struct cfq_data *cfqd)
2398 for (i = 0; i < IOPRIO_BE_NR; i++) {
2399 if (cfqd->async_cfqq[0][i])
2400 cfq_put_queue(cfqd->async_cfqq[0][i]);
2401 if (cfqd->async_cfqq[1][i])
2402 cfq_put_queue(cfqd->async_cfqq[1][i]);
2405 if (cfqd->async_idle_cfqq)
2406 cfq_put_queue(cfqd->async_idle_cfqq);
2409 static void cfq_exit_queue(struct elevator_queue *e)
2411 struct cfq_data *cfqd = e->elevator_data;
2412 struct request_queue *q = cfqd->queue;
2414 cfq_shutdown_timer_wq(cfqd);
2416 spin_lock_irq(q->queue_lock);
2418 if (cfqd->active_queue)
2419 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2421 while (!list_empty(&cfqd->cic_list)) {
2422 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2423 struct cfq_io_context,
2426 __cfq_exit_single_io_context(cfqd, cic);
2429 cfq_put_async_queues(cfqd);
2431 spin_unlock_irq(q->queue_lock);
2433 cfq_shutdown_timer_wq(cfqd);
2438 static void *cfq_init_queue(struct request_queue *q)
2440 struct cfq_data *cfqd;
2443 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2447 cfqd->service_tree = CFQ_RB_ROOT;
2450 * Not strictly needed (since RB_ROOT just clears the node and we
2451 * zeroed cfqd on alloc), but better be safe in case someone decides
2452 * to add magic to the rb code
2454 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2455 cfqd->prio_trees[i] = RB_ROOT;
2458 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2459 * Grab a permanent reference to it, so that the normal code flow
2460 * will not attempt to free it.
2462 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2463 atomic_inc(&cfqd->oom_cfqq.ref);
2465 INIT_LIST_HEAD(&cfqd->cic_list);
2469 init_timer(&cfqd->idle_slice_timer);
2470 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2471 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2473 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
2475 cfqd->cfq_quantum = cfq_quantum;
2476 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2477 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2478 cfqd->cfq_back_max = cfq_back_max;
2479 cfqd->cfq_back_penalty = cfq_back_penalty;
2480 cfqd->cfq_slice[0] = cfq_slice_async;
2481 cfqd->cfq_slice[1] = cfq_slice_sync;
2482 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2483 cfqd->cfq_slice_idle = cfq_slice_idle;
2484 cfqd->cfq_desktop = 1;
2490 static void cfq_slab_kill(void)
2493 * Caller already ensured that pending RCU callbacks are completed,
2494 * so we should have no busy allocations at this point.
2497 kmem_cache_destroy(cfq_pool);
2499 kmem_cache_destroy(cfq_ioc_pool);
2502 static int __init cfq_slab_setup(void)
2504 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2508 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2519 * sysfs parts below -->
2522 cfq_var_show(unsigned int var, char *page)
2524 return sprintf(page, "%d\n", var);
2528 cfq_var_store(unsigned int *var, const char *page, size_t count)
2530 char *p = (char *) page;
2532 *var = simple_strtoul(p, &p, 10);
2536 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2537 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2539 struct cfq_data *cfqd = e->elevator_data; \
2540 unsigned int __data = __VAR; \
2542 __data = jiffies_to_msecs(__data); \
2543 return cfq_var_show(__data, (page)); \
2545 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2546 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2547 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2548 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2549 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2550 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2551 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2552 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2553 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2554 SHOW_FUNCTION(cfq_desktop_show, cfqd->cfq_desktop, 0);
2555 #undef SHOW_FUNCTION
2557 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2558 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2560 struct cfq_data *cfqd = e->elevator_data; \
2561 unsigned int __data; \
2562 int ret = cfq_var_store(&__data, (page), count); \
2563 if (__data < (MIN)) \
2565 else if (__data > (MAX)) \
2568 *(__PTR) = msecs_to_jiffies(__data); \
2570 *(__PTR) = __data; \
2573 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2574 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2576 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2578 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2579 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2581 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2582 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2583 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2584 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2586 STORE_FUNCTION(cfq_desktop_store, &cfqd->cfq_desktop, 0, 1, 0);
2587 #undef STORE_FUNCTION
2589 #define CFQ_ATTR(name) \
2590 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2592 static struct elv_fs_entry cfq_attrs[] = {
2594 CFQ_ATTR(fifo_expire_sync),
2595 CFQ_ATTR(fifo_expire_async),
2596 CFQ_ATTR(back_seek_max),
2597 CFQ_ATTR(back_seek_penalty),
2598 CFQ_ATTR(slice_sync),
2599 CFQ_ATTR(slice_async),
2600 CFQ_ATTR(slice_async_rq),
2601 CFQ_ATTR(slice_idle),
2606 static struct elevator_type iosched_cfq = {
2608 .elevator_merge_fn = cfq_merge,
2609 .elevator_merged_fn = cfq_merged_request,
2610 .elevator_merge_req_fn = cfq_merged_requests,
2611 .elevator_allow_merge_fn = cfq_allow_merge,
2612 .elevator_dispatch_fn = cfq_dispatch_requests,
2613 .elevator_add_req_fn = cfq_insert_request,
2614 .elevator_activate_req_fn = cfq_activate_request,
2615 .elevator_deactivate_req_fn = cfq_deactivate_request,
2616 .elevator_queue_empty_fn = cfq_queue_empty,
2617 .elevator_completed_req_fn = cfq_completed_request,
2618 .elevator_former_req_fn = elv_rb_former_request,
2619 .elevator_latter_req_fn = elv_rb_latter_request,
2620 .elevator_set_req_fn = cfq_set_request,
2621 .elevator_put_req_fn = cfq_put_request,
2622 .elevator_may_queue_fn = cfq_may_queue,
2623 .elevator_init_fn = cfq_init_queue,
2624 .elevator_exit_fn = cfq_exit_queue,
2625 .trim = cfq_free_io_context,
2627 .elevator_attrs = cfq_attrs,
2628 .elevator_name = "cfq",
2629 .elevator_owner = THIS_MODULE,
2632 static int __init cfq_init(void)
2635 * could be 0 on HZ < 1000 setups
2637 if (!cfq_slice_async)
2638 cfq_slice_async = 1;
2639 if (!cfq_slice_idle)
2642 if (cfq_slab_setup())
2645 elv_register(&iosched_cfq);
2650 static void __exit cfq_exit(void)
2652 DECLARE_COMPLETION_ONSTACK(all_gone);
2653 elv_unregister(&iosched_cfq);
2654 ioc_gone = &all_gone;
2655 /* ioc_gone's update must be visible before reading ioc_count */
2659 * this also protects us from entering cfq_slab_kill() with
2660 * pending RCU callbacks
2662 if (elv_ioc_count_read(cfq_ioc_count))
2663 wait_for_completion(&all_gone);
2667 module_init(cfq_init);
2668 module_exit(cfq_exit);
2670 MODULE_AUTHOR("Jens Axboe");
2671 MODULE_LICENSE("GPL");
2672 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");