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, 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;
138 * Used to track any pending rt requests so we can pre-empt current
139 * non-RT cfqq in service when this value is non-zero.
141 unsigned int busy_rt_queues;
147 * queue-depth detection
152 int rq_in_driver_peak;
155 * idle window management
157 struct timer_list idle_slice_timer;
158 struct work_struct unplug_work;
160 struct cfq_queue *active_queue;
161 struct cfq_io_context *active_cic;
164 * async queue for each priority case
166 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
167 struct cfq_queue *async_idle_cfqq;
169 sector_t last_position;
172 * tunables, see top of file
174 unsigned int cfq_quantum;
175 unsigned int cfq_fifo_expire[2];
176 unsigned int cfq_back_penalty;
177 unsigned int cfq_back_max;
178 unsigned int cfq_slice[2];
179 unsigned int cfq_slice_async_rq;
180 unsigned int cfq_slice_idle;
182 struct list_head cic_list;
185 * Fallback dummy cfqq for extreme OOM conditions
187 struct cfq_queue oom_cfqq;
190 enum cfqq_state_flags {
191 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
192 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
193 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
194 CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
195 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
196 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
197 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
198 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
199 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
200 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
201 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
204 #define CFQ_CFQQ_FNS(name) \
205 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
207 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
209 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
211 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
213 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
215 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
219 CFQ_CFQQ_FNS(wait_request);
220 CFQ_CFQQ_FNS(must_dispatch);
221 CFQ_CFQQ_FNS(must_alloc);
222 CFQ_CFQQ_FNS(must_alloc_slice);
223 CFQ_CFQQ_FNS(fifo_expire);
224 CFQ_CFQQ_FNS(idle_window);
225 CFQ_CFQQ_FNS(prio_changed);
226 CFQ_CFQQ_FNS(slice_new);
231 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
232 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
233 #define cfq_log(cfqd, fmt, args...) \
234 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
236 static void cfq_dispatch_insert(struct request_queue *, struct request *);
237 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
238 struct io_context *, gfp_t);
239 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
240 struct io_context *);
242 static inline int rq_in_driver(struct cfq_data *cfqd)
244 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
247 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
250 return cic->cfqq[!!is_sync];
253 static inline void cic_set_cfqq(struct cfq_io_context *cic,
254 struct cfq_queue *cfqq, int is_sync)
256 cic->cfqq[!!is_sync] = cfqq;
260 * We regard a request as SYNC, if it's either a read or has the SYNC bit
261 * set (in which case it could also be direct WRITE).
263 static inline int cfq_bio_sync(struct bio *bio)
265 if (bio_data_dir(bio) == READ || bio_sync(bio))
272 * scheduler run of queue, if there are requests pending and no one in the
273 * driver that will restart queueing
275 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
277 if (cfqd->busy_queues) {
278 cfq_log(cfqd, "schedule dispatch");
279 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
283 static int cfq_queue_empty(struct request_queue *q)
285 struct cfq_data *cfqd = q->elevator->elevator_data;
287 return !cfqd->busy_queues;
291 * Scale schedule slice based on io priority. Use the sync time slice only
292 * if a queue is marked sync and has sync io queued. A sync queue with async
293 * io only, should not get full sync slice length.
295 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
298 const int base_slice = cfqd->cfq_slice[sync];
300 WARN_ON(prio >= IOPRIO_BE_NR);
302 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
306 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
308 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
312 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
314 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
315 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
319 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
320 * isn't valid until the first request from the dispatch is activated
321 * and the slice time set.
323 static inline int cfq_slice_used(struct cfq_queue *cfqq)
325 if (cfq_cfqq_slice_new(cfqq))
327 if (time_before(jiffies, cfqq->slice_end))
334 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
335 * We choose the request that is closest to the head right now. Distance
336 * behind the head is penalized and only allowed to a certain extent.
338 static struct request *
339 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
341 sector_t last, s1, s2, d1 = 0, d2 = 0;
342 unsigned long back_max;
343 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
344 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
345 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
347 if (rq1 == NULL || rq1 == rq2)
352 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
354 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
356 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
358 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
361 s1 = blk_rq_pos(rq1);
362 s2 = blk_rq_pos(rq2);
364 last = cfqd->last_position;
367 * by definition, 1KiB is 2 sectors
369 back_max = cfqd->cfq_back_max * 2;
372 * Strict one way elevator _except_ in the case where we allow
373 * short backward seeks which are biased as twice the cost of a
374 * similar forward seek.
378 else if (s1 + back_max >= last)
379 d1 = (last - s1) * cfqd->cfq_back_penalty;
381 wrap |= CFQ_RQ1_WRAP;
385 else if (s2 + back_max >= last)
386 d2 = (last - s2) * cfqd->cfq_back_penalty;
388 wrap |= CFQ_RQ2_WRAP;
390 /* Found required data */
393 * By doing switch() on the bit mask "wrap" we avoid having to
394 * check two variables for all permutations: --> faster!
397 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
413 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
416 * Since both rqs are wrapped,
417 * start with the one that's further behind head
418 * (--> only *one* back seek required),
419 * since back seek takes more time than forward.
429 * The below is leftmost cache rbtree addon
431 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
434 root->left = rb_first(&root->rb);
437 return rb_entry(root->left, struct cfq_queue, rb_node);
442 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
448 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
452 rb_erase_init(n, &root->rb);
456 * would be nice to take fifo expire time into account as well
458 static struct request *
459 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
460 struct request *last)
462 struct rb_node *rbnext = rb_next(&last->rb_node);
463 struct rb_node *rbprev = rb_prev(&last->rb_node);
464 struct request *next = NULL, *prev = NULL;
466 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
469 prev = rb_entry_rq(rbprev);
472 next = rb_entry_rq(rbnext);
474 rbnext = rb_first(&cfqq->sort_list);
475 if (rbnext && rbnext != &last->rb_node)
476 next = rb_entry_rq(rbnext);
479 return cfq_choose_req(cfqd, next, prev);
482 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
483 struct cfq_queue *cfqq)
486 * just an approximation, should be ok.
488 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
489 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
493 * The cfqd->service_tree holds all pending cfq_queue's that have
494 * requests waiting to be processed. It is sorted in the order that
495 * we will service the queues.
497 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
500 struct rb_node **p, *parent;
501 struct cfq_queue *__cfqq;
502 unsigned long rb_key;
505 if (cfq_class_idle(cfqq)) {
506 rb_key = CFQ_IDLE_DELAY;
507 parent = rb_last(&cfqd->service_tree.rb);
508 if (parent && parent != &cfqq->rb_node) {
509 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
510 rb_key += __cfqq->rb_key;
513 } else if (!add_front) {
514 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
515 rb_key += cfqq->slice_resid;
516 cfqq->slice_resid = 0;
520 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
522 * same position, nothing more to do
524 if (rb_key == cfqq->rb_key)
527 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
532 p = &cfqd->service_tree.rb.rb_node;
537 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
540 * sort RT queues first, we always want to give
541 * preference to them. IDLE queues goes to the back.
542 * after that, sort on the next service time.
544 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
546 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
548 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
550 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
552 else if (rb_key < __cfqq->rb_key)
557 if (n == &(*p)->rb_right)
564 cfqd->service_tree.left = &cfqq->rb_node;
566 cfqq->rb_key = rb_key;
567 rb_link_node(&cfqq->rb_node, parent, p);
568 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
571 static struct cfq_queue *
572 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
573 sector_t sector, struct rb_node **ret_parent,
574 struct rb_node ***rb_link)
576 struct rb_node **p, *parent;
577 struct cfq_queue *cfqq = NULL;
585 cfqq = rb_entry(parent, struct cfq_queue, p_node);
588 * Sort strictly based on sector. Smallest to the left,
589 * largest to the right.
591 if (sector > blk_rq_pos(cfqq->next_rq))
593 else if (sector < blk_rq_pos(cfqq->next_rq))
601 *ret_parent = parent;
607 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
609 struct rb_node **p, *parent;
610 struct cfq_queue *__cfqq;
613 rb_erase(&cfqq->p_node, cfqq->p_root);
617 if (cfq_class_idle(cfqq))
622 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
623 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
624 blk_rq_pos(cfqq->next_rq), &parent, &p);
626 rb_link_node(&cfqq->p_node, parent, p);
627 rb_insert_color(&cfqq->p_node, cfqq->p_root);
633 * Update cfqq's position in the service tree.
635 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
638 * Resorting requires the cfqq to be on the RR list already.
640 if (cfq_cfqq_on_rr(cfqq)) {
641 cfq_service_tree_add(cfqd, cfqq, 0);
642 cfq_prio_tree_add(cfqd, cfqq);
647 * add to busy list of queues for service, trying to be fair in ordering
648 * the pending list according to last request service
650 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
652 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
653 BUG_ON(cfq_cfqq_on_rr(cfqq));
654 cfq_mark_cfqq_on_rr(cfqq);
656 if (cfq_class_rt(cfqq))
657 cfqd->busy_rt_queues++;
659 cfq_resort_rr_list(cfqd, cfqq);
663 * Called when the cfqq no longer has requests pending, remove it from
666 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
668 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
669 BUG_ON(!cfq_cfqq_on_rr(cfqq));
670 cfq_clear_cfqq_on_rr(cfqq);
672 if (!RB_EMPTY_NODE(&cfqq->rb_node))
673 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
675 rb_erase(&cfqq->p_node, cfqq->p_root);
679 BUG_ON(!cfqd->busy_queues);
681 if (cfq_class_rt(cfqq))
682 cfqd->busy_rt_queues--;
686 * rb tree support functions
688 static void cfq_del_rq_rb(struct request *rq)
690 struct cfq_queue *cfqq = RQ_CFQQ(rq);
691 struct cfq_data *cfqd = cfqq->cfqd;
692 const int sync = rq_is_sync(rq);
694 BUG_ON(!cfqq->queued[sync]);
695 cfqq->queued[sync]--;
697 elv_rb_del(&cfqq->sort_list, rq);
699 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
700 cfq_del_cfqq_rr(cfqd, cfqq);
703 static void cfq_add_rq_rb(struct request *rq)
705 struct cfq_queue *cfqq = RQ_CFQQ(rq);
706 struct cfq_data *cfqd = cfqq->cfqd;
707 struct request *__alias, *prev;
709 cfqq->queued[rq_is_sync(rq)]++;
712 * looks a little odd, but the first insert might return an alias.
713 * if that happens, put the alias on the dispatch list
715 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
716 cfq_dispatch_insert(cfqd->queue, __alias);
718 if (!cfq_cfqq_on_rr(cfqq))
719 cfq_add_cfqq_rr(cfqd, cfqq);
722 * check if this request is a better next-serve candidate
724 prev = cfqq->next_rq;
725 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
728 * adjust priority tree position, if ->next_rq changes
730 if (prev != cfqq->next_rq)
731 cfq_prio_tree_add(cfqd, cfqq);
733 BUG_ON(!cfqq->next_rq);
736 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
738 elv_rb_del(&cfqq->sort_list, rq);
739 cfqq->queued[rq_is_sync(rq)]--;
743 static struct request *
744 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
746 struct task_struct *tsk = current;
747 struct cfq_io_context *cic;
748 struct cfq_queue *cfqq;
750 cic = cfq_cic_lookup(cfqd, tsk->io_context);
754 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
756 sector_t sector = bio->bi_sector + bio_sectors(bio);
758 return elv_rb_find(&cfqq->sort_list, sector);
764 static void cfq_activate_request(struct request_queue *q, struct request *rq)
766 struct cfq_data *cfqd = q->elevator->elevator_data;
768 cfqd->rq_in_driver[rq_is_sync(rq)]++;
769 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
772 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
775 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
777 struct cfq_data *cfqd = q->elevator->elevator_data;
778 const int sync = rq_is_sync(rq);
780 WARN_ON(!cfqd->rq_in_driver[sync]);
781 cfqd->rq_in_driver[sync]--;
782 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
786 static void cfq_remove_request(struct request *rq)
788 struct cfq_queue *cfqq = RQ_CFQQ(rq);
790 if (cfqq->next_rq == rq)
791 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
793 list_del_init(&rq->queuelist);
796 cfqq->cfqd->rq_queued--;
797 if (rq_is_meta(rq)) {
798 WARN_ON(!cfqq->meta_pending);
799 cfqq->meta_pending--;
803 static int cfq_merge(struct request_queue *q, struct request **req,
806 struct cfq_data *cfqd = q->elevator->elevator_data;
807 struct request *__rq;
809 __rq = cfq_find_rq_fmerge(cfqd, bio);
810 if (__rq && elv_rq_merge_ok(__rq, bio)) {
812 return ELEVATOR_FRONT_MERGE;
815 return ELEVATOR_NO_MERGE;
818 static void cfq_merged_request(struct request_queue *q, struct request *req,
821 if (type == ELEVATOR_FRONT_MERGE) {
822 struct cfq_queue *cfqq = RQ_CFQQ(req);
824 cfq_reposition_rq_rb(cfqq, req);
829 cfq_merged_requests(struct request_queue *q, struct request *rq,
830 struct request *next)
833 * reposition in fifo if next is older than rq
835 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
836 time_before(next->start_time, rq->start_time))
837 list_move(&rq->queuelist, &next->queuelist);
839 cfq_remove_request(next);
842 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
845 struct cfq_data *cfqd = q->elevator->elevator_data;
846 struct cfq_io_context *cic;
847 struct cfq_queue *cfqq;
850 * Disallow merge of a sync bio into an async request.
852 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
856 * Lookup the cfqq that this bio will be queued with. Allow
857 * merge only if rq is queued there.
859 cic = cfq_cic_lookup(cfqd, current->io_context);
863 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
864 if (cfqq == RQ_CFQQ(rq))
870 static void __cfq_set_active_queue(struct cfq_data *cfqd,
871 struct cfq_queue *cfqq)
874 cfq_log_cfqq(cfqd, cfqq, "set_active");
876 cfqq->slice_dispatch = 0;
878 cfq_clear_cfqq_wait_request(cfqq);
879 cfq_clear_cfqq_must_dispatch(cfqq);
880 cfq_clear_cfqq_must_alloc_slice(cfqq);
881 cfq_clear_cfqq_fifo_expire(cfqq);
882 cfq_mark_cfqq_slice_new(cfqq);
884 del_timer(&cfqd->idle_slice_timer);
887 cfqd->active_queue = cfqq;
891 * current cfqq expired its slice (or was too idle), select new one
894 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
897 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
899 if (cfq_cfqq_wait_request(cfqq))
900 del_timer(&cfqd->idle_slice_timer);
902 cfq_clear_cfqq_wait_request(cfqq);
905 * store what was left of this slice, if the queue idled/timed out
907 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
908 cfqq->slice_resid = cfqq->slice_end - jiffies;
909 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
912 cfq_resort_rr_list(cfqd, cfqq);
914 if (cfqq == cfqd->active_queue)
915 cfqd->active_queue = NULL;
917 if (cfqd->active_cic) {
918 put_io_context(cfqd->active_cic->ioc);
919 cfqd->active_cic = NULL;
923 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
925 struct cfq_queue *cfqq = cfqd->active_queue;
928 __cfq_slice_expired(cfqd, cfqq, timed_out);
932 * Get next queue for service. Unless we have a queue preemption,
933 * we'll simply select the first cfqq in the service tree.
935 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
937 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
940 return cfq_rb_first(&cfqd->service_tree);
944 * Get and set a new active queue for service.
946 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
947 struct cfq_queue *cfqq)
950 cfqq = cfq_get_next_queue(cfqd);
952 cfq_clear_cfqq_coop(cfqq);
955 __cfq_set_active_queue(cfqd, cfqq);
959 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
962 if (blk_rq_pos(rq) >= cfqd->last_position)
963 return blk_rq_pos(rq) - cfqd->last_position;
965 return cfqd->last_position - blk_rq_pos(rq);
968 #define CIC_SEEK_THR 8 * 1024
969 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
971 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
973 struct cfq_io_context *cic = cfqd->active_cic;
974 sector_t sdist = cic->seek_mean;
976 if (!sample_valid(cic->seek_samples))
977 sdist = CIC_SEEK_THR;
979 return cfq_dist_from_last(cfqd, rq) <= sdist;
982 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
983 struct cfq_queue *cur_cfqq)
985 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
986 struct rb_node *parent, *node;
987 struct cfq_queue *__cfqq;
988 sector_t sector = cfqd->last_position;
990 if (RB_EMPTY_ROOT(root))
994 * First, if we find a request starting at the end of the last
995 * request, choose it.
997 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1002 * If the exact sector wasn't found, the parent of the NULL leaf
1003 * will contain the closest sector.
1005 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1006 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1009 if (blk_rq_pos(__cfqq->next_rq) < sector)
1010 node = rb_next(&__cfqq->p_node);
1012 node = rb_prev(&__cfqq->p_node);
1016 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1017 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1025 * cur_cfqq - passed in so that we don't decide that the current queue is
1026 * closely cooperating with itself.
1028 * So, basically we're assuming that that cur_cfqq has dispatched at least
1029 * one request, and that cfqd->last_position reflects a position on the disk
1030 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1033 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1034 struct cfq_queue *cur_cfqq,
1037 struct cfq_queue *cfqq;
1040 * A valid cfq_io_context is necessary to compare requests against
1041 * the seek_mean of the current cfqq.
1043 if (!cfqd->active_cic)
1047 * We should notice if some of the queues are cooperating, eg
1048 * working closely on the same area of the disk. In that case,
1049 * we can group them together and don't waste time idling.
1051 cfqq = cfqq_close(cfqd, cur_cfqq);
1055 if (cfq_cfqq_coop(cfqq))
1059 cfq_mark_cfqq_coop(cfqq);
1063 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1065 struct cfq_queue *cfqq = cfqd->active_queue;
1066 struct cfq_io_context *cic;
1070 * SSD device without seek penalty, disable idling. But only do so
1071 * for devices that support queuing, otherwise we still have a problem
1072 * with sync vs async workloads.
1074 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1077 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1078 WARN_ON(cfq_cfqq_slice_new(cfqq));
1081 * idle is disabled, either manually or by past process history
1083 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1087 * still requests with the driver, don't idle
1089 if (rq_in_driver(cfqd))
1093 * task has exited, don't wait
1095 cic = cfqd->active_cic;
1096 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1099 cfq_mark_cfqq_wait_request(cfqq);
1102 * we don't want to idle for seeks, but we do want to allow
1103 * fair distribution of slice time for a process doing back-to-back
1104 * seeks. so allow a little bit of time for him to submit a new rq
1106 sl = cfqd->cfq_slice_idle;
1107 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1108 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1110 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1111 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1115 * Move request from internal lists to the request queue dispatch list.
1117 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1119 struct cfq_data *cfqd = q->elevator->elevator_data;
1120 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1122 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1124 cfq_remove_request(rq);
1126 elv_dispatch_sort(q, rq);
1128 if (cfq_cfqq_sync(cfqq))
1129 cfqd->sync_flight++;
1133 * return expired entry, or NULL to just start from scratch in rbtree
1135 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1137 struct cfq_data *cfqd = cfqq->cfqd;
1141 if (cfq_cfqq_fifo_expire(cfqq))
1144 cfq_mark_cfqq_fifo_expire(cfqq);
1146 if (list_empty(&cfqq->fifo))
1149 fifo = cfq_cfqq_sync(cfqq);
1150 rq = rq_entry_fifo(cfqq->fifo.next);
1152 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
1155 cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
1160 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1162 const int base_rq = cfqd->cfq_slice_async_rq;
1164 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1166 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1170 * Select a queue for service. If we have a current active queue,
1171 * check whether to continue servicing it, or retrieve and set a new one.
1173 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1175 struct cfq_queue *cfqq, *new_cfqq = NULL;
1177 cfqq = cfqd->active_queue;
1182 * The active queue has run out of time, expire it and select new.
1184 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1188 * If we have a RT cfqq waiting, then we pre-empt the current non-rt
1191 if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
1193 * We simulate this as cfqq timed out so that it gets to bank
1194 * the remaining of its time slice.
1196 cfq_log_cfqq(cfqd, cfqq, "preempt");
1197 cfq_slice_expired(cfqd, 1);
1202 * The active queue has requests and isn't expired, allow it to
1205 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1209 * If another queue has a request waiting within our mean seek
1210 * distance, let it run. The expire code will check for close
1211 * cooperators and put the close queue at the front of the service
1214 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1219 * No requests pending. If the active queue still has requests in
1220 * flight or is idling for a new request, allow either of these
1221 * conditions to happen (or time out) before selecting a new queue.
1223 if (timer_pending(&cfqd->idle_slice_timer) ||
1224 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1230 cfq_slice_expired(cfqd, 0);
1232 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1237 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1241 while (cfqq->next_rq) {
1242 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1246 BUG_ON(!list_empty(&cfqq->fifo));
1251 * Drain our current requests. Used for barriers and when switching
1252 * io schedulers on-the-fly.
1254 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1256 struct cfq_queue *cfqq;
1259 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1260 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1262 cfq_slice_expired(cfqd, 0);
1264 BUG_ON(cfqd->busy_queues);
1266 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1271 * Dispatch a request from cfqq, moving them to the request queue
1274 static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1278 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1281 * follow expired path, else get first next available
1283 rq = cfq_check_fifo(cfqq);
1288 * insert request into driver dispatch list
1290 cfq_dispatch_insert(cfqd->queue, rq);
1292 if (!cfqd->active_cic) {
1293 struct cfq_io_context *cic = RQ_CIC(rq);
1295 atomic_long_inc(&cic->ioc->refcount);
1296 cfqd->active_cic = cic;
1301 * Find the cfqq that we need to service and move a request from that to the
1304 static int cfq_dispatch_requests(struct request_queue *q, int force)
1306 struct cfq_data *cfqd = q->elevator->elevator_data;
1307 struct cfq_queue *cfqq;
1308 unsigned int max_dispatch;
1310 if (!cfqd->busy_queues)
1313 if (unlikely(force))
1314 return cfq_forced_dispatch(cfqd);
1316 cfqq = cfq_select_queue(cfqd);
1321 * Drain async requests before we start sync IO
1323 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1327 * If this is an async queue and we have sync IO in flight, let it wait
1329 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1332 max_dispatch = cfqd->cfq_quantum;
1333 if (cfq_class_idle(cfqq))
1337 * Does this cfqq already have too much IO in flight?
1339 if (cfqq->dispatched >= max_dispatch) {
1341 * idle queue must always only have a single IO in flight
1343 if (cfq_class_idle(cfqq))
1347 * We have other queues, don't allow more IO from this one
1349 if (cfqd->busy_queues > 1)
1353 * we are the only queue, allow up to 4 times of 'quantum'
1355 if (cfqq->dispatched >= 4 * max_dispatch)
1360 * Dispatch a request from this cfqq
1362 cfq_dispatch_request(cfqd, cfqq);
1363 cfqq->slice_dispatch++;
1364 cfq_clear_cfqq_must_dispatch(cfqq);
1367 * expire an async queue immediately if it has used up its slice. idle
1368 * queue always expire after 1 dispatch round.
1370 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1371 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1372 cfq_class_idle(cfqq))) {
1373 cfqq->slice_end = jiffies + 1;
1374 cfq_slice_expired(cfqd, 0);
1377 cfq_log(cfqd, "dispatched a request");
1382 * task holds one reference to the queue, dropped when task exits. each rq
1383 * in-flight on this queue also holds a reference, dropped when rq is freed.
1385 * queue lock must be held here.
1387 static void cfq_put_queue(struct cfq_queue *cfqq)
1389 struct cfq_data *cfqd = cfqq->cfqd;
1391 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1393 if (!atomic_dec_and_test(&cfqq->ref))
1396 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1397 BUG_ON(rb_first(&cfqq->sort_list));
1398 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1399 BUG_ON(cfq_cfqq_on_rr(cfqq));
1401 if (unlikely(cfqd->active_queue == cfqq)) {
1402 __cfq_slice_expired(cfqd, cfqq, 0);
1403 cfq_schedule_dispatch(cfqd);
1406 kmem_cache_free(cfq_pool, cfqq);
1410 * Must always be called with the rcu_read_lock() held
1413 __call_for_each_cic(struct io_context *ioc,
1414 void (*func)(struct io_context *, struct cfq_io_context *))
1416 struct cfq_io_context *cic;
1417 struct hlist_node *n;
1419 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1424 * Call func for each cic attached to this ioc.
1427 call_for_each_cic(struct io_context *ioc,
1428 void (*func)(struct io_context *, struct cfq_io_context *))
1431 __call_for_each_cic(ioc, func);
1435 static void cfq_cic_free_rcu(struct rcu_head *head)
1437 struct cfq_io_context *cic;
1439 cic = container_of(head, struct cfq_io_context, rcu_head);
1441 kmem_cache_free(cfq_ioc_pool, cic);
1442 elv_ioc_count_dec(ioc_count);
1446 * CFQ scheduler is exiting, grab exit lock and check
1447 * the pending io context count. If it hits zero,
1448 * complete ioc_gone and set it back to NULL
1450 spin_lock(&ioc_gone_lock);
1451 if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
1455 spin_unlock(&ioc_gone_lock);
1459 static void cfq_cic_free(struct cfq_io_context *cic)
1461 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1464 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1466 unsigned long flags;
1468 BUG_ON(!cic->dead_key);
1470 spin_lock_irqsave(&ioc->lock, flags);
1471 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1472 hlist_del_rcu(&cic->cic_list);
1473 spin_unlock_irqrestore(&ioc->lock, flags);
1479 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1480 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1481 * and ->trim() which is called with the task lock held
1483 static void cfq_free_io_context(struct io_context *ioc)
1486 * ioc->refcount is zero here, or we are called from elv_unregister(),
1487 * so no more cic's are allowed to be linked into this ioc. So it
1488 * should be ok to iterate over the known list, we will see all cic's
1489 * since no new ones are added.
1491 __call_for_each_cic(ioc, cic_free_func);
1494 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1496 if (unlikely(cfqq == cfqd->active_queue)) {
1497 __cfq_slice_expired(cfqd, cfqq, 0);
1498 cfq_schedule_dispatch(cfqd);
1501 cfq_put_queue(cfqq);
1504 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1505 struct cfq_io_context *cic)
1507 struct io_context *ioc = cic->ioc;
1509 list_del_init(&cic->queue_list);
1512 * Make sure key == NULL is seen for dead queues
1515 cic->dead_key = (unsigned long) cic->key;
1518 if (ioc->ioc_data == cic)
1519 rcu_assign_pointer(ioc->ioc_data, NULL);
1521 if (cic->cfqq[BLK_RW_ASYNC]) {
1522 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1523 cic->cfqq[BLK_RW_ASYNC] = NULL;
1526 if (cic->cfqq[BLK_RW_SYNC]) {
1527 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1528 cic->cfqq[BLK_RW_SYNC] = NULL;
1532 static void cfq_exit_single_io_context(struct io_context *ioc,
1533 struct cfq_io_context *cic)
1535 struct cfq_data *cfqd = cic->key;
1538 struct request_queue *q = cfqd->queue;
1539 unsigned long flags;
1541 spin_lock_irqsave(q->queue_lock, flags);
1544 * Ensure we get a fresh copy of the ->key to prevent
1545 * race between exiting task and queue
1547 smp_read_barrier_depends();
1549 __cfq_exit_single_io_context(cfqd, cic);
1551 spin_unlock_irqrestore(q->queue_lock, flags);
1556 * The process that ioc belongs to has exited, we need to clean up
1557 * and put the internal structures we have that belongs to that process.
1559 static void cfq_exit_io_context(struct io_context *ioc)
1561 call_for_each_cic(ioc, cfq_exit_single_io_context);
1564 static struct cfq_io_context *
1565 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1567 struct cfq_io_context *cic;
1569 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1572 cic->last_end_request = jiffies;
1573 INIT_LIST_HEAD(&cic->queue_list);
1574 INIT_HLIST_NODE(&cic->cic_list);
1575 cic->dtor = cfq_free_io_context;
1576 cic->exit = cfq_exit_io_context;
1577 elv_ioc_count_inc(ioc_count);
1583 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1585 struct task_struct *tsk = current;
1588 if (!cfq_cfqq_prio_changed(cfqq))
1591 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1592 switch (ioprio_class) {
1594 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1595 case IOPRIO_CLASS_NONE:
1597 * no prio set, inherit CPU scheduling settings
1599 cfqq->ioprio = task_nice_ioprio(tsk);
1600 cfqq->ioprio_class = task_nice_ioclass(tsk);
1602 case IOPRIO_CLASS_RT:
1603 cfqq->ioprio = task_ioprio(ioc);
1604 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1606 case IOPRIO_CLASS_BE:
1607 cfqq->ioprio = task_ioprio(ioc);
1608 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1610 case IOPRIO_CLASS_IDLE:
1611 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1613 cfq_clear_cfqq_idle_window(cfqq);
1618 * keep track of original prio settings in case we have to temporarily
1619 * elevate the priority of this queue
1621 cfqq->org_ioprio = cfqq->ioprio;
1622 cfqq->org_ioprio_class = cfqq->ioprio_class;
1623 cfq_clear_cfqq_prio_changed(cfqq);
1626 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1628 struct cfq_data *cfqd = cic->key;
1629 struct cfq_queue *cfqq;
1630 unsigned long flags;
1632 if (unlikely(!cfqd))
1635 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1637 cfqq = cic->cfqq[BLK_RW_ASYNC];
1639 struct cfq_queue *new_cfqq;
1640 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1643 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1644 cfq_put_queue(cfqq);
1648 cfqq = cic->cfqq[BLK_RW_SYNC];
1650 cfq_mark_cfqq_prio_changed(cfqq);
1652 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1655 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1657 call_for_each_cic(ioc, changed_ioprio);
1658 ioc->ioprio_changed = 0;
1661 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1662 pid_t pid, int is_sync)
1664 RB_CLEAR_NODE(&cfqq->rb_node);
1665 RB_CLEAR_NODE(&cfqq->p_node);
1666 INIT_LIST_HEAD(&cfqq->fifo);
1668 atomic_set(&cfqq->ref, 0);
1671 cfq_mark_cfqq_prio_changed(cfqq);
1674 if (!cfq_class_idle(cfqq))
1675 cfq_mark_cfqq_idle_window(cfqq);
1676 cfq_mark_cfqq_sync(cfqq);
1681 static struct cfq_queue *
1682 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1683 struct io_context *ioc, gfp_t gfp_mask)
1685 struct cfq_queue *cfqq, *new_cfqq = NULL;
1686 struct cfq_io_context *cic;
1689 cic = cfq_cic_lookup(cfqd, ioc);
1690 /* cic always exists here */
1691 cfqq = cic_to_cfqq(cic, is_sync);
1694 * Always try a new alloc if we fell back to the OOM cfqq
1695 * originally, since it should just be a temporary situation.
1697 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1702 } else if (gfp_mask & __GFP_WAIT) {
1703 spin_unlock_irq(cfqd->queue->queue_lock);
1704 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1705 gfp_mask | __GFP_ZERO,
1707 spin_lock_irq(cfqd->queue->queue_lock);
1711 cfqq = kmem_cache_alloc_node(cfq_pool,
1712 gfp_mask | __GFP_ZERO,
1717 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1718 cfq_init_prio_data(cfqq, ioc);
1719 cfq_log_cfqq(cfqd, cfqq, "alloced");
1721 cfqq = &cfqd->oom_cfqq;
1725 kmem_cache_free(cfq_pool, new_cfqq);
1730 static struct cfq_queue **
1731 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1733 switch (ioprio_class) {
1734 case IOPRIO_CLASS_RT:
1735 return &cfqd->async_cfqq[0][ioprio];
1736 case IOPRIO_CLASS_BE:
1737 return &cfqd->async_cfqq[1][ioprio];
1738 case IOPRIO_CLASS_IDLE:
1739 return &cfqd->async_idle_cfqq;
1745 static struct cfq_queue *
1746 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1749 const int ioprio = task_ioprio(ioc);
1750 const int ioprio_class = task_ioprio_class(ioc);
1751 struct cfq_queue **async_cfqq = NULL;
1752 struct cfq_queue *cfqq = NULL;
1755 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1760 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1763 * pin the queue now that it's allocated, scheduler exit will prune it
1765 if (!is_sync && !(*async_cfqq)) {
1766 atomic_inc(&cfqq->ref);
1770 atomic_inc(&cfqq->ref);
1775 * We drop cfq io contexts lazily, so we may find a dead one.
1778 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1779 struct cfq_io_context *cic)
1781 unsigned long flags;
1783 WARN_ON(!list_empty(&cic->queue_list));
1785 spin_lock_irqsave(&ioc->lock, flags);
1787 BUG_ON(ioc->ioc_data == cic);
1789 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1790 hlist_del_rcu(&cic->cic_list);
1791 spin_unlock_irqrestore(&ioc->lock, flags);
1796 static struct cfq_io_context *
1797 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1799 struct cfq_io_context *cic;
1800 unsigned long flags;
1809 * we maintain a last-hit cache, to avoid browsing over the tree
1811 cic = rcu_dereference(ioc->ioc_data);
1812 if (cic && cic->key == cfqd) {
1818 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1822 /* ->key must be copied to avoid race with cfq_exit_queue() */
1825 cfq_drop_dead_cic(cfqd, ioc, cic);
1830 spin_lock_irqsave(&ioc->lock, flags);
1831 rcu_assign_pointer(ioc->ioc_data, cic);
1832 spin_unlock_irqrestore(&ioc->lock, flags);
1840 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1841 * the process specific cfq io context when entered from the block layer.
1842 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1844 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1845 struct cfq_io_context *cic, gfp_t gfp_mask)
1847 unsigned long flags;
1850 ret = radix_tree_preload(gfp_mask);
1855 spin_lock_irqsave(&ioc->lock, flags);
1856 ret = radix_tree_insert(&ioc->radix_root,
1857 (unsigned long) cfqd, cic);
1859 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1860 spin_unlock_irqrestore(&ioc->lock, flags);
1862 radix_tree_preload_end();
1865 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1866 list_add(&cic->queue_list, &cfqd->cic_list);
1867 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1872 printk(KERN_ERR "cfq: cic link failed!\n");
1878 * Setup general io context and cfq io context. There can be several cfq
1879 * io contexts per general io context, if this process is doing io to more
1880 * than one device managed by cfq.
1882 static struct cfq_io_context *
1883 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1885 struct io_context *ioc = NULL;
1886 struct cfq_io_context *cic;
1888 might_sleep_if(gfp_mask & __GFP_WAIT);
1890 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1894 cic = cfq_cic_lookup(cfqd, ioc);
1898 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1902 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1906 smp_read_barrier_depends();
1907 if (unlikely(ioc->ioprio_changed))
1908 cfq_ioc_set_ioprio(ioc);
1914 put_io_context(ioc);
1919 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1921 unsigned long elapsed = jiffies - cic->last_end_request;
1922 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1924 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1925 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1926 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1930 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1936 if (!cic->last_request_pos)
1938 else if (cic->last_request_pos < blk_rq_pos(rq))
1939 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1941 sdist = cic->last_request_pos - blk_rq_pos(rq);
1944 * Don't allow the seek distance to get too large from the
1945 * odd fragment, pagein, etc
1947 if (cic->seek_samples <= 60) /* second&third seek */
1948 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1950 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1952 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1953 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1954 total = cic->seek_total + (cic->seek_samples/2);
1955 do_div(total, cic->seek_samples);
1956 cic->seek_mean = (sector_t)total;
1960 * Disable idle window if the process thinks too long or seeks so much that
1964 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1965 struct cfq_io_context *cic)
1967 int old_idle, enable_idle;
1970 * Don't idle for async or idle io prio class
1972 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1975 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1977 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1978 (cfqd->hw_tag && CIC_SEEKY(cic)))
1980 else if (sample_valid(cic->ttime_samples)) {
1981 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1987 if (old_idle != enable_idle) {
1988 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
1990 cfq_mark_cfqq_idle_window(cfqq);
1992 cfq_clear_cfqq_idle_window(cfqq);
1997 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1998 * no or if we aren't sure, a 1 will cause a preempt.
2001 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
2004 struct cfq_queue *cfqq;
2006 cfqq = cfqd->active_queue;
2010 if (cfq_slice_used(cfqq))
2013 if (cfq_class_idle(new_cfqq))
2016 if (cfq_class_idle(cfqq))
2020 * if the new request is sync, but the currently running queue is
2021 * not, let the sync request have priority.
2023 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2027 * So both queues are sync. Let the new request get disk time if
2028 * it's a metadata request and the current queue is doing regular IO.
2030 if (rq_is_meta(rq) && !cfqq->meta_pending)
2034 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2036 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2039 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2043 * if this request is as-good as one we would expect from the
2044 * current cfqq, let it preempt
2046 if (cfq_rq_close(cfqd, rq))
2053 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2054 * let it have half of its nominal slice.
2056 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2058 cfq_log_cfqq(cfqd, cfqq, "preempt");
2059 cfq_slice_expired(cfqd, 1);
2062 * Put the new queue at the front of the of the current list,
2063 * so we know that it will be selected next.
2065 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2067 cfq_service_tree_add(cfqd, cfqq, 1);
2069 cfqq->slice_end = 0;
2070 cfq_mark_cfqq_slice_new(cfqq);
2074 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2075 * something we should do about it
2078 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2081 struct cfq_io_context *cic = RQ_CIC(rq);
2085 cfqq->meta_pending++;
2087 cfq_update_io_thinktime(cfqd, cic);
2088 cfq_update_io_seektime(cfqd, cic, rq);
2089 cfq_update_idle_window(cfqd, cfqq, cic);
2091 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2093 if (cfqq == cfqd->active_queue) {
2095 * Remember that we saw a request from this process, but
2096 * don't start queuing just yet. Otherwise we risk seeing lots
2097 * of tiny requests, because we disrupt the normal plugging
2098 * and merging. If the request is already larger than a single
2099 * page, let it rip immediately. For that case we assume that
2100 * merging is already done. Ditto for a busy system that
2101 * has other work pending, don't risk delaying until the
2102 * idle timer unplug to continue working.
2104 if (cfq_cfqq_wait_request(cfqq)) {
2105 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2106 cfqd->busy_queues > 1) {
2107 del_timer(&cfqd->idle_slice_timer);
2108 __blk_run_queue(cfqd->queue);
2110 cfq_mark_cfqq_must_dispatch(cfqq);
2112 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2114 * not the active queue - expire current slice if it is
2115 * idle and has expired it's mean thinktime or this new queue
2116 * has some old slice time left and is of higher priority or
2117 * this new queue is RT and the current one is BE
2119 cfq_preempt_queue(cfqd, cfqq);
2120 __blk_run_queue(cfqd->queue);
2124 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2126 struct cfq_data *cfqd = q->elevator->elevator_data;
2127 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2129 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2130 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2134 list_add_tail(&rq->queuelist, &cfqq->fifo);
2136 cfq_rq_enqueued(cfqd, cfqq, rq);
2140 * Update hw_tag based on peak queue depth over 50 samples under
2143 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2145 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2146 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
2148 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2149 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2152 if (cfqd->hw_tag_samples++ < 50)
2155 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2160 cfqd->hw_tag_samples = 0;
2161 cfqd->rq_in_driver_peak = 0;
2164 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2166 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2167 struct cfq_data *cfqd = cfqq->cfqd;
2168 const int sync = rq_is_sync(rq);
2172 cfq_log_cfqq(cfqd, cfqq, "complete");
2174 cfq_update_hw_tag(cfqd);
2176 WARN_ON(!cfqd->rq_in_driver[sync]);
2177 WARN_ON(!cfqq->dispatched);
2178 cfqd->rq_in_driver[sync]--;
2181 if (cfq_cfqq_sync(cfqq))
2182 cfqd->sync_flight--;
2185 RQ_CIC(rq)->last_end_request = now;
2188 * If this is the active queue, check if it needs to be expired,
2189 * or if we want to idle in case it has no pending requests.
2191 if (cfqd->active_queue == cfqq) {
2192 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2194 if (cfq_cfqq_slice_new(cfqq)) {
2195 cfq_set_prio_slice(cfqd, cfqq);
2196 cfq_clear_cfqq_slice_new(cfqq);
2199 * If there are no requests waiting in this queue, and
2200 * there are other queues ready to issue requests, AND
2201 * those other queues are issuing requests within our
2202 * mean seek distance, give them a chance to run instead
2205 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2206 cfq_slice_expired(cfqd, 1);
2207 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2208 sync && !rq_noidle(rq))
2209 cfq_arm_slice_timer(cfqd);
2212 if (!rq_in_driver(cfqd))
2213 cfq_schedule_dispatch(cfqd);
2217 * we temporarily boost lower priority queues if they are holding fs exclusive
2218 * resources. they are boosted to normal prio (CLASS_BE/4)
2220 static void cfq_prio_boost(struct cfq_queue *cfqq)
2222 if (has_fs_excl()) {
2224 * boost idle prio on transactions that would lock out other
2225 * users of the filesystem
2227 if (cfq_class_idle(cfqq))
2228 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2229 if (cfqq->ioprio > IOPRIO_NORM)
2230 cfqq->ioprio = IOPRIO_NORM;
2233 * check if we need to unboost the queue
2235 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2236 cfqq->ioprio_class = cfqq->org_ioprio_class;
2237 if (cfqq->ioprio != cfqq->org_ioprio)
2238 cfqq->ioprio = cfqq->org_ioprio;
2242 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2244 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
2245 !cfq_cfqq_must_alloc_slice(cfqq)) {
2246 cfq_mark_cfqq_must_alloc_slice(cfqq);
2247 return ELV_MQUEUE_MUST;
2250 return ELV_MQUEUE_MAY;
2253 static int cfq_may_queue(struct request_queue *q, int rw)
2255 struct cfq_data *cfqd = q->elevator->elevator_data;
2256 struct task_struct *tsk = current;
2257 struct cfq_io_context *cic;
2258 struct cfq_queue *cfqq;
2261 * don't force setup of a queue from here, as a call to may_queue
2262 * does not necessarily imply that a request actually will be queued.
2263 * so just lookup a possibly existing queue, or return 'may queue'
2266 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2268 return ELV_MQUEUE_MAY;
2270 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2272 cfq_init_prio_data(cfqq, cic->ioc);
2273 cfq_prio_boost(cfqq);
2275 return __cfq_may_queue(cfqq);
2278 return ELV_MQUEUE_MAY;
2282 * queue lock held here
2284 static void cfq_put_request(struct request *rq)
2286 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2289 const int rw = rq_data_dir(rq);
2291 BUG_ON(!cfqq->allocated[rw]);
2292 cfqq->allocated[rw]--;
2294 put_io_context(RQ_CIC(rq)->ioc);
2296 rq->elevator_private = NULL;
2297 rq->elevator_private2 = NULL;
2299 cfq_put_queue(cfqq);
2304 * Allocate cfq data structures associated with this request.
2307 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2309 struct cfq_data *cfqd = q->elevator->elevator_data;
2310 struct cfq_io_context *cic;
2311 const int rw = rq_data_dir(rq);
2312 const int is_sync = rq_is_sync(rq);
2313 struct cfq_queue *cfqq;
2314 unsigned long flags;
2316 might_sleep_if(gfp_mask & __GFP_WAIT);
2318 cic = cfq_get_io_context(cfqd, gfp_mask);
2320 spin_lock_irqsave(q->queue_lock, flags);
2325 cfqq = cic_to_cfqq(cic, is_sync);
2326 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2327 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2328 cic_set_cfqq(cic, cfqq, is_sync);
2331 cfqq->allocated[rw]++;
2332 cfq_clear_cfqq_must_alloc(cfqq);
2333 atomic_inc(&cfqq->ref);
2335 spin_unlock_irqrestore(q->queue_lock, flags);
2337 rq->elevator_private = cic;
2338 rq->elevator_private2 = cfqq;
2343 put_io_context(cic->ioc);
2345 cfq_schedule_dispatch(cfqd);
2346 spin_unlock_irqrestore(q->queue_lock, flags);
2347 cfq_log(cfqd, "set_request fail");
2351 static void cfq_kick_queue(struct work_struct *work)
2353 struct cfq_data *cfqd =
2354 container_of(work, struct cfq_data, unplug_work);
2355 struct request_queue *q = cfqd->queue;
2357 spin_lock_irq(q->queue_lock);
2358 __blk_run_queue(cfqd->queue);
2359 spin_unlock_irq(q->queue_lock);
2363 * Timer running if the active_queue is currently idling inside its time slice
2365 static void cfq_idle_slice_timer(unsigned long data)
2367 struct cfq_data *cfqd = (struct cfq_data *) data;
2368 struct cfq_queue *cfqq;
2369 unsigned long flags;
2372 cfq_log(cfqd, "idle timer fired");
2374 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2376 cfqq = cfqd->active_queue;
2381 * We saw a request before the queue expired, let it through
2383 if (cfq_cfqq_must_dispatch(cfqq))
2389 if (cfq_slice_used(cfqq))
2393 * only expire and reinvoke request handler, if there are
2394 * other queues with pending requests
2396 if (!cfqd->busy_queues)
2400 * not expired and it has a request pending, let it dispatch
2402 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2406 cfq_slice_expired(cfqd, timed_out);
2408 cfq_schedule_dispatch(cfqd);
2410 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2413 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2415 del_timer_sync(&cfqd->idle_slice_timer);
2416 cancel_work_sync(&cfqd->unplug_work);
2419 static void cfq_put_async_queues(struct cfq_data *cfqd)
2423 for (i = 0; i < IOPRIO_BE_NR; i++) {
2424 if (cfqd->async_cfqq[0][i])
2425 cfq_put_queue(cfqd->async_cfqq[0][i]);
2426 if (cfqd->async_cfqq[1][i])
2427 cfq_put_queue(cfqd->async_cfqq[1][i]);
2430 if (cfqd->async_idle_cfqq)
2431 cfq_put_queue(cfqd->async_idle_cfqq);
2434 static void cfq_exit_queue(struct elevator_queue *e)
2436 struct cfq_data *cfqd = e->elevator_data;
2437 struct request_queue *q = cfqd->queue;
2439 cfq_shutdown_timer_wq(cfqd);
2441 spin_lock_irq(q->queue_lock);
2443 if (cfqd->active_queue)
2444 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2446 while (!list_empty(&cfqd->cic_list)) {
2447 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2448 struct cfq_io_context,
2451 __cfq_exit_single_io_context(cfqd, cic);
2454 cfq_put_async_queues(cfqd);
2456 spin_unlock_irq(q->queue_lock);
2458 cfq_shutdown_timer_wq(cfqd);
2463 static void *cfq_init_queue(struct request_queue *q)
2465 struct cfq_data *cfqd;
2468 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2472 cfqd->service_tree = CFQ_RB_ROOT;
2475 * Not strictly needed (since RB_ROOT just clears the node and we
2476 * zeroed cfqd on alloc), but better be safe in case someone decides
2477 * to add magic to the rb code
2479 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2480 cfqd->prio_trees[i] = RB_ROOT;
2483 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2484 * Grab a permanent reference to it, so that the normal code flow
2485 * will not attempt to free it.
2487 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2488 atomic_inc(&cfqd->oom_cfqq.ref);
2490 INIT_LIST_HEAD(&cfqd->cic_list);
2494 init_timer(&cfqd->idle_slice_timer);
2495 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2496 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2498 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
2500 cfqd->cfq_quantum = cfq_quantum;
2501 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2502 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2503 cfqd->cfq_back_max = cfq_back_max;
2504 cfqd->cfq_back_penalty = cfq_back_penalty;
2505 cfqd->cfq_slice[0] = cfq_slice_async;
2506 cfqd->cfq_slice[1] = cfq_slice_sync;
2507 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2508 cfqd->cfq_slice_idle = cfq_slice_idle;
2514 static void cfq_slab_kill(void)
2517 * Caller already ensured that pending RCU callbacks are completed,
2518 * so we should have no busy allocations at this point.
2521 kmem_cache_destroy(cfq_pool);
2523 kmem_cache_destroy(cfq_ioc_pool);
2526 static int __init cfq_slab_setup(void)
2528 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2532 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2543 * sysfs parts below -->
2546 cfq_var_show(unsigned int var, char *page)
2548 return sprintf(page, "%d\n", var);
2552 cfq_var_store(unsigned int *var, const char *page, size_t count)
2554 char *p = (char *) page;
2556 *var = simple_strtoul(p, &p, 10);
2560 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2561 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2563 struct cfq_data *cfqd = e->elevator_data; \
2564 unsigned int __data = __VAR; \
2566 __data = jiffies_to_msecs(__data); \
2567 return cfq_var_show(__data, (page)); \
2569 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2570 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2571 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2572 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2573 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2574 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2575 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2576 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2577 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2578 #undef SHOW_FUNCTION
2580 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2581 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2583 struct cfq_data *cfqd = e->elevator_data; \
2584 unsigned int __data; \
2585 int ret = cfq_var_store(&__data, (page), count); \
2586 if (__data < (MIN)) \
2588 else if (__data > (MAX)) \
2591 *(__PTR) = msecs_to_jiffies(__data); \
2593 *(__PTR) = __data; \
2596 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2597 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2599 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2601 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2602 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2604 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2605 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2606 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2607 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2609 #undef STORE_FUNCTION
2611 #define CFQ_ATTR(name) \
2612 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2614 static struct elv_fs_entry cfq_attrs[] = {
2616 CFQ_ATTR(fifo_expire_sync),
2617 CFQ_ATTR(fifo_expire_async),
2618 CFQ_ATTR(back_seek_max),
2619 CFQ_ATTR(back_seek_penalty),
2620 CFQ_ATTR(slice_sync),
2621 CFQ_ATTR(slice_async),
2622 CFQ_ATTR(slice_async_rq),
2623 CFQ_ATTR(slice_idle),
2627 static struct elevator_type iosched_cfq = {
2629 .elevator_merge_fn = cfq_merge,
2630 .elevator_merged_fn = cfq_merged_request,
2631 .elevator_merge_req_fn = cfq_merged_requests,
2632 .elevator_allow_merge_fn = cfq_allow_merge,
2633 .elevator_dispatch_fn = cfq_dispatch_requests,
2634 .elevator_add_req_fn = cfq_insert_request,
2635 .elevator_activate_req_fn = cfq_activate_request,
2636 .elevator_deactivate_req_fn = cfq_deactivate_request,
2637 .elevator_queue_empty_fn = cfq_queue_empty,
2638 .elevator_completed_req_fn = cfq_completed_request,
2639 .elevator_former_req_fn = elv_rb_former_request,
2640 .elevator_latter_req_fn = elv_rb_latter_request,
2641 .elevator_set_req_fn = cfq_set_request,
2642 .elevator_put_req_fn = cfq_put_request,
2643 .elevator_may_queue_fn = cfq_may_queue,
2644 .elevator_init_fn = cfq_init_queue,
2645 .elevator_exit_fn = cfq_exit_queue,
2646 .trim = cfq_free_io_context,
2648 .elevator_attrs = cfq_attrs,
2649 .elevator_name = "cfq",
2650 .elevator_owner = THIS_MODULE,
2653 static int __init cfq_init(void)
2656 * could be 0 on HZ < 1000 setups
2658 if (!cfq_slice_async)
2659 cfq_slice_async = 1;
2660 if (!cfq_slice_idle)
2663 if (cfq_slab_setup())
2666 elv_register(&iosched_cfq);
2671 static void __exit cfq_exit(void)
2673 DECLARE_COMPLETION_ONSTACK(all_gone);
2674 elv_unregister(&iosched_cfq);
2675 ioc_gone = &all_gone;
2676 /* ioc_gone's update must be visible before reading ioc_count */
2680 * this also protects us from entering cfq_slab_kill() with
2681 * pending RCU callbacks
2683 if (elv_ioc_count_read(ioc_count))
2684 wait_for_completion(&all_gone);
2688 module_init(cfq_init);
2689 module_exit(cfq_exit);
2691 MODULE_AUTHOR("Jens Axboe");
2692 MODULE_LICENSE("GPL");
2693 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");