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/jiffies.h>
13 #include <linux/rbtree.h>
14 #include <linux/ioprio.h>
15 #include <linux/blktrace_api.h>
16 #include "blk-cgroup.h"
21 /* max queue in one round of service */
22 static const int cfq_quantum = 4;
23 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
24 /* maximum backwards seek, in KiB */
25 static const int cfq_back_max = 16 * 1024;
26 /* penalty of a backwards seek */
27 static const int cfq_back_penalty = 2;
28 static const int cfq_slice_sync = HZ / 10;
29 static int cfq_slice_async = HZ / 25;
30 static const int cfq_slice_async_rq = 2;
31 static int cfq_slice_idle = HZ / 125;
32 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
33 static const int cfq_hist_divisor = 4;
36 * offset from end of service tree
38 #define CFQ_IDLE_DELAY (HZ / 5)
41 * below this threshold, we consider thinktime immediate
43 #define CFQ_MIN_TT (2)
46 * Allow merged cfqqs to perform this amount of seeky I/O before
47 * deciding to break the queues up again.
49 #define CFQQ_COOP_TOUT (HZ)
51 #define CFQ_SLICE_SCALE (5)
52 #define CFQ_HW_QUEUE_MIN (5)
53 #define CFQ_SERVICE_SHIFT 12
56 ((struct cfq_io_context *) (rq)->elevator_private)
57 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
59 static struct kmem_cache *cfq_pool;
60 static struct kmem_cache *cfq_ioc_pool;
62 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
63 static struct completion *ioc_gone;
64 static DEFINE_SPINLOCK(ioc_gone_lock);
66 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
67 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
68 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
70 #define sample_valid(samples) ((samples) > 80)
71 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
74 * Most of our rbtree usage is for sorting with min extraction, so
75 * if we cache the leftmost node we don't have to walk down the tree
76 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
77 * move this into the elevator for the rq sorting as well.
84 struct rb_node *active;
85 unsigned total_weight;
87 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
90 * Per process-grouping structure
95 /* various state flags, see below */
98 struct cfq_data *cfqd;
99 /* service_tree member */
100 struct rb_node rb_node;
101 /* service_tree key */
102 unsigned long rb_key;
103 /* prio tree member */
104 struct rb_node p_node;
105 /* prio tree root we belong to, if any */
106 struct rb_root *p_root;
107 /* sorted list of pending requests */
108 struct rb_root sort_list;
109 /* if fifo isn't expired, next request to serve */
110 struct request *next_rq;
111 /* requests queued in sort_list */
113 /* currently allocated requests */
115 /* fifo list of requests in sort_list */
116 struct list_head fifo;
118 unsigned long slice_end;
120 unsigned int slice_dispatch;
122 /* pending metadata requests */
124 /* number of requests that are on the dispatch list or inside driver */
127 /* io prio of this group */
128 unsigned short ioprio, org_ioprio;
129 unsigned short ioprio_class, org_ioprio_class;
131 unsigned int seek_samples;
134 sector_t last_request_pos;
135 unsigned long seeky_start;
139 struct cfq_rb_root *service_tree;
140 struct cfq_queue *new_cfqq;
141 struct cfq_group *cfqg;
145 * First index in the service_trees.
146 * IDLE is handled separately, so it has negative index
155 * Second index in the service_trees.
159 SYNC_NOIDLE_WORKLOAD = 1,
163 /* This is per cgroup per device grouping structure */
165 /* group service_tree member */
166 struct rb_node rb_node;
168 /* group service_tree key */
173 /* number of cfqq currently on this group */
176 /* Per group busy queus average. Useful for workload slice calc. */
177 unsigned int busy_queues_avg[2];
179 * rr lists of queues with requests, onle rr for each priority class.
180 * Counts are embedded in the cfq_rb_root
182 struct cfq_rb_root service_trees[2][3];
183 struct cfq_rb_root service_tree_idle;
187 * Per block device queue structure
190 struct request_queue *queue;
191 /* Root service tree for cfq_groups */
192 struct cfq_rb_root grp_service_tree;
193 struct cfq_group root_group;
194 /* Number of active cfq groups on group service tree */
198 * The priority currently being served
200 enum wl_prio_t serving_prio;
201 enum wl_type_t serving_type;
202 unsigned long workload_expires;
203 struct cfq_group *serving_group;
204 bool noidle_tree_requires_idle;
207 * Each priority tree is sorted by next_request position. These
208 * trees are used when determining if two or more queues are
209 * interleaving requests (see cfq_close_cooperator).
211 struct rb_root prio_trees[CFQ_PRIO_LISTS];
213 unsigned int busy_queues;
219 * queue-depth detection
225 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
226 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
229 int hw_tag_est_depth;
230 unsigned int hw_tag_samples;
233 * idle window management
235 struct timer_list idle_slice_timer;
236 struct work_struct unplug_work;
238 struct cfq_queue *active_queue;
239 struct cfq_io_context *active_cic;
242 * async queue for each priority case
244 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
245 struct cfq_queue *async_idle_cfqq;
247 sector_t last_position;
250 * tunables, see top of file
252 unsigned int cfq_quantum;
253 unsigned int cfq_fifo_expire[2];
254 unsigned int cfq_back_penalty;
255 unsigned int cfq_back_max;
256 unsigned int cfq_slice[2];
257 unsigned int cfq_slice_async_rq;
258 unsigned int cfq_slice_idle;
259 unsigned int cfq_latency;
261 struct list_head cic_list;
264 * Fallback dummy cfqq for extreme OOM conditions
266 struct cfq_queue oom_cfqq;
268 unsigned long last_end_sync_rq;
271 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
274 struct cfq_data *cfqd)
279 if (prio == IDLE_WORKLOAD)
280 return &cfqg->service_tree_idle;
282 return &cfqg->service_trees[prio][type];
285 enum cfqq_state_flags {
286 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
287 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
288 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
289 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
290 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
291 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
292 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
293 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
294 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
295 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
296 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
299 #define CFQ_CFQQ_FNS(name) \
300 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
302 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
304 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
306 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
308 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
310 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
314 CFQ_CFQQ_FNS(wait_request);
315 CFQ_CFQQ_FNS(must_dispatch);
316 CFQ_CFQQ_FNS(must_alloc_slice);
317 CFQ_CFQQ_FNS(fifo_expire);
318 CFQ_CFQQ_FNS(idle_window);
319 CFQ_CFQQ_FNS(prio_changed);
320 CFQ_CFQQ_FNS(slice_new);
326 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
327 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
328 #define cfq_log(cfqd, fmt, args...) \
329 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
331 /* Traverses through cfq group service trees */
332 #define for_each_cfqg_st(cfqg, i, j, st) \
333 for (i = 0; i <= IDLE_WORKLOAD; i++) \
334 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
335 : &cfqg->service_tree_idle; \
336 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
337 (i == IDLE_WORKLOAD && j == 0); \
338 j++, st = i < IDLE_WORKLOAD ? \
339 &cfqg->service_trees[i][j]: NULL) \
342 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
344 if (cfq_class_idle(cfqq))
345 return IDLE_WORKLOAD;
346 if (cfq_class_rt(cfqq))
352 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
354 if (!cfq_cfqq_sync(cfqq))
355 return ASYNC_WORKLOAD;
356 if (!cfq_cfqq_idle_window(cfqq))
357 return SYNC_NOIDLE_WORKLOAD;
358 return SYNC_WORKLOAD;
361 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
362 struct cfq_data *cfqd,
363 struct cfq_group *cfqg)
365 if (wl == IDLE_WORKLOAD)
366 return cfqg->service_tree_idle.count;
368 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
369 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
370 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
373 static void cfq_dispatch_insert(struct request_queue *, struct request *);
374 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
375 struct io_context *, gfp_t);
376 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
377 struct io_context *);
379 static inline int rq_in_driver(struct cfq_data *cfqd)
381 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
384 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
387 return cic->cfqq[is_sync];
390 static inline void cic_set_cfqq(struct cfq_io_context *cic,
391 struct cfq_queue *cfqq, bool is_sync)
393 cic->cfqq[is_sync] = cfqq;
397 * We regard a request as SYNC, if it's either a read or has the SYNC bit
398 * set (in which case it could also be direct WRITE).
400 static inline bool cfq_bio_sync(struct bio *bio)
402 return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
406 * scheduler run of queue, if there are requests pending and no one in the
407 * driver that will restart queueing
409 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
411 if (cfqd->busy_queues) {
412 cfq_log(cfqd, "schedule dispatch");
413 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
417 static int cfq_queue_empty(struct request_queue *q)
419 struct cfq_data *cfqd = q->elevator->elevator_data;
421 return !cfqd->rq_queued;
425 * Scale schedule slice based on io priority. Use the sync time slice only
426 * if a queue is marked sync and has sync io queued. A sync queue with async
427 * io only, should not get full sync slice length.
429 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
432 const int base_slice = cfqd->cfq_slice[sync];
434 WARN_ON(prio >= IOPRIO_BE_NR);
436 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
440 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
442 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
445 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
447 u64 d = delta << CFQ_SERVICE_SHIFT;
449 d = d * BLKIO_WEIGHT_DEFAULT;
450 do_div(d, cfqg->weight);
454 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
456 s64 delta = (s64)(vdisktime - min_vdisktime);
458 min_vdisktime = vdisktime;
460 return min_vdisktime;
463 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
465 s64 delta = (s64)(vdisktime - min_vdisktime);
467 min_vdisktime = vdisktime;
469 return min_vdisktime;
472 static void update_min_vdisktime(struct cfq_rb_root *st)
474 u64 vdisktime = st->min_vdisktime;
475 struct cfq_group *cfqg;
478 cfqg = rb_entry_cfqg(st->active);
479 vdisktime = cfqg->vdisktime;
483 cfqg = rb_entry_cfqg(st->left);
484 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
487 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
491 * get averaged number of queues of RT/BE priority.
492 * average is updated, with a formula that gives more weight to higher numbers,
493 * to quickly follows sudden increases and decrease slowly
496 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
497 struct cfq_group *cfqg, bool rt)
499 unsigned min_q, max_q;
500 unsigned mult = cfq_hist_divisor - 1;
501 unsigned round = cfq_hist_divisor / 2;
502 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
504 min_q = min(cfqg->busy_queues_avg[rt], busy);
505 max_q = max(cfqg->busy_queues_avg[rt], busy);
506 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
508 return cfqg->busy_queues_avg[rt];
511 static inline unsigned
512 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
514 struct cfq_rb_root *st = &cfqd->grp_service_tree;
516 return cfq_target_latency * cfqg->weight / st->total_weight;
520 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
522 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
523 if (cfqd->cfq_latency) {
525 * interested queues (we consider only the ones with the same
526 * priority class in the cfq group)
528 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
530 unsigned sync_slice = cfqd->cfq_slice[1];
531 unsigned expect_latency = sync_slice * iq;
532 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
534 if (expect_latency > group_slice) {
535 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
536 /* scale low_slice according to IO priority
537 * and sync vs async */
539 min(slice, base_low_slice * slice / sync_slice);
540 /* the adapted slice value is scaled to fit all iqs
541 * into the target latency */
542 slice = max(slice * group_slice / expect_latency,
546 cfqq->slice_end = jiffies + slice;
547 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
551 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
552 * isn't valid until the first request from the dispatch is activated
553 * and the slice time set.
555 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
557 if (cfq_cfqq_slice_new(cfqq))
559 if (time_before(jiffies, cfqq->slice_end))
566 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
567 * We choose the request that is closest to the head right now. Distance
568 * behind the head is penalized and only allowed to a certain extent.
570 static struct request *
571 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
573 sector_t s1, s2, d1 = 0, d2 = 0;
574 unsigned long back_max;
575 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
576 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
577 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
579 if (rq1 == NULL || rq1 == rq2)
584 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
586 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
588 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
590 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
593 s1 = blk_rq_pos(rq1);
594 s2 = blk_rq_pos(rq2);
597 * by definition, 1KiB is 2 sectors
599 back_max = cfqd->cfq_back_max * 2;
602 * Strict one way elevator _except_ in the case where we allow
603 * short backward seeks which are biased as twice the cost of a
604 * similar forward seek.
608 else if (s1 + back_max >= last)
609 d1 = (last - s1) * cfqd->cfq_back_penalty;
611 wrap |= CFQ_RQ1_WRAP;
615 else if (s2 + back_max >= last)
616 d2 = (last - s2) * cfqd->cfq_back_penalty;
618 wrap |= CFQ_RQ2_WRAP;
620 /* Found required data */
623 * By doing switch() on the bit mask "wrap" we avoid having to
624 * check two variables for all permutations: --> faster!
627 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
643 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
646 * Since both rqs are wrapped,
647 * start with the one that's further behind head
648 * (--> only *one* back seek required),
649 * since back seek takes more time than forward.
659 * The below is leftmost cache rbtree addon
661 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
663 /* Service tree is empty */
668 root->left = rb_first(&root->rb);
671 return rb_entry(root->left, struct cfq_queue, rb_node);
676 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
679 root->left = rb_first(&root->rb);
682 return rb_entry_cfqg(root->left);
687 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
693 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
697 rb_erase_init(n, &root->rb);
702 * would be nice to take fifo expire time into account as well
704 static struct request *
705 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
706 struct request *last)
708 struct rb_node *rbnext = rb_next(&last->rb_node);
709 struct rb_node *rbprev = rb_prev(&last->rb_node);
710 struct request *next = NULL, *prev = NULL;
712 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
715 prev = rb_entry_rq(rbprev);
718 next = rb_entry_rq(rbnext);
720 rbnext = rb_first(&cfqq->sort_list);
721 if (rbnext && rbnext != &last->rb_node)
722 next = rb_entry_rq(rbnext);
725 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
728 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
729 struct cfq_queue *cfqq)
732 * just an approximation, should be ok.
734 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
735 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
739 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
741 return cfqg->vdisktime - st->min_vdisktime;
745 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
747 struct rb_node **node = &st->rb.rb_node;
748 struct rb_node *parent = NULL;
749 struct cfq_group *__cfqg;
750 s64 key = cfqg_key(st, cfqg);
753 while (*node != NULL) {
755 __cfqg = rb_entry_cfqg(parent);
757 if (key < cfqg_key(st, __cfqg))
758 node = &parent->rb_left;
760 node = &parent->rb_right;
766 st->left = &cfqg->rb_node;
768 rb_link_node(&cfqg->rb_node, parent, node);
769 rb_insert_color(&cfqg->rb_node, &st->rb);
773 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
775 struct cfq_rb_root *st = &cfqd->grp_service_tree;
776 struct cfq_group *__cfqg;
784 * Currently put the group at the end. Later implement something
785 * so that groups get lesser vtime based on their weights, so that
786 * if group does not loose all if it was not continously backlogged.
788 n = rb_last(&st->rb);
790 __cfqg = rb_entry_cfqg(n);
791 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
793 cfqg->vdisktime = st->min_vdisktime;
795 __cfq_group_service_tree_add(st, cfqg);
798 st->total_weight += cfqg->weight;
802 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
804 struct cfq_rb_root *st = &cfqd->grp_service_tree;
806 if (st->active == &cfqg->rb_node)
809 BUG_ON(cfqg->nr_cfqq < 1);
812 /* If there are other cfq queues under this group, don't delete it */
818 st->total_weight -= cfqg->weight;
819 if (!RB_EMPTY_NODE(&cfqg->rb_node))
820 cfq_rb_erase(&cfqg->rb_node, st);
824 * The cfqd->service_trees holds all pending cfq_queue's that have
825 * requests waiting to be processed. It is sorted in the order that
826 * we will service the queues.
828 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
831 struct rb_node **p, *parent;
832 struct cfq_queue *__cfqq;
833 unsigned long rb_key;
834 struct cfq_rb_root *service_tree;
837 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
838 cfqq_type(cfqq), cfqd);
839 if (cfq_class_idle(cfqq)) {
840 rb_key = CFQ_IDLE_DELAY;
841 parent = rb_last(&service_tree->rb);
842 if (parent && parent != &cfqq->rb_node) {
843 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
844 rb_key += __cfqq->rb_key;
847 } else if (!add_front) {
849 * Get our rb key offset. Subtract any residual slice
850 * value carried from last service. A negative resid
851 * count indicates slice overrun, and this should position
852 * the next service time further away in the tree.
854 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
855 rb_key -= cfqq->slice_resid;
856 cfqq->slice_resid = 0;
859 __cfqq = cfq_rb_first(service_tree);
860 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
863 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
865 * same position, nothing more to do
867 if (rb_key == cfqq->rb_key &&
868 cfqq->service_tree == service_tree)
871 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
872 cfqq->service_tree = NULL;
877 cfqq->service_tree = service_tree;
878 p = &service_tree->rb.rb_node;
883 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
886 * sort by key, that represents service time.
888 if (time_before(rb_key, __cfqq->rb_key))
899 service_tree->left = &cfqq->rb_node;
901 cfqq->rb_key = rb_key;
902 rb_link_node(&cfqq->rb_node, parent, p);
903 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
904 service_tree->count++;
905 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
908 static struct cfq_queue *
909 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
910 sector_t sector, struct rb_node **ret_parent,
911 struct rb_node ***rb_link)
913 struct rb_node **p, *parent;
914 struct cfq_queue *cfqq = NULL;
922 cfqq = rb_entry(parent, struct cfq_queue, p_node);
925 * Sort strictly based on sector. Smallest to the left,
926 * largest to the right.
928 if (sector > blk_rq_pos(cfqq->next_rq))
930 else if (sector < blk_rq_pos(cfqq->next_rq))
938 *ret_parent = parent;
944 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
946 struct rb_node **p, *parent;
947 struct cfq_queue *__cfqq;
950 rb_erase(&cfqq->p_node, cfqq->p_root);
954 if (cfq_class_idle(cfqq))
959 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
960 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
961 blk_rq_pos(cfqq->next_rq), &parent, &p);
963 rb_link_node(&cfqq->p_node, parent, p);
964 rb_insert_color(&cfqq->p_node, cfqq->p_root);
970 * Update cfqq's position in the service tree.
972 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
975 * Resorting requires the cfqq to be on the RR list already.
977 if (cfq_cfqq_on_rr(cfqq)) {
978 cfq_service_tree_add(cfqd, cfqq, 0);
979 cfq_prio_tree_add(cfqd, cfqq);
984 * add to busy list of queues for service, trying to be fair in ordering
985 * the pending list according to last request service
987 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
989 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
990 BUG_ON(cfq_cfqq_on_rr(cfqq));
991 cfq_mark_cfqq_on_rr(cfqq);
994 cfq_resort_rr_list(cfqd, cfqq);
998 * Called when the cfqq no longer has requests pending, remove it from
1001 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1003 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1004 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1005 cfq_clear_cfqq_on_rr(cfqq);
1007 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1008 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1009 cfqq->service_tree = NULL;
1012 rb_erase(&cfqq->p_node, cfqq->p_root);
1013 cfqq->p_root = NULL;
1016 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1017 BUG_ON(!cfqd->busy_queues);
1018 cfqd->busy_queues--;
1022 * rb tree support functions
1024 static void cfq_del_rq_rb(struct request *rq)
1026 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1027 const int sync = rq_is_sync(rq);
1029 BUG_ON(!cfqq->queued[sync]);
1030 cfqq->queued[sync]--;
1032 elv_rb_del(&cfqq->sort_list, rq);
1034 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1036 * Queue will be deleted from service tree when we actually
1037 * expire it later. Right now just remove it from prio tree
1041 rb_erase(&cfqq->p_node, cfqq->p_root);
1042 cfqq->p_root = NULL;
1047 static void cfq_add_rq_rb(struct request *rq)
1049 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1050 struct cfq_data *cfqd = cfqq->cfqd;
1051 struct request *__alias, *prev;
1053 cfqq->queued[rq_is_sync(rq)]++;
1056 * looks a little odd, but the first insert might return an alias.
1057 * if that happens, put the alias on the dispatch list
1059 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1060 cfq_dispatch_insert(cfqd->queue, __alias);
1062 if (!cfq_cfqq_on_rr(cfqq))
1063 cfq_add_cfqq_rr(cfqd, cfqq);
1066 * check if this request is a better next-serve candidate
1068 prev = cfqq->next_rq;
1069 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1072 * adjust priority tree position, if ->next_rq changes
1074 if (prev != cfqq->next_rq)
1075 cfq_prio_tree_add(cfqd, cfqq);
1077 BUG_ON(!cfqq->next_rq);
1080 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1082 elv_rb_del(&cfqq->sort_list, rq);
1083 cfqq->queued[rq_is_sync(rq)]--;
1087 static struct request *
1088 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1090 struct task_struct *tsk = current;
1091 struct cfq_io_context *cic;
1092 struct cfq_queue *cfqq;
1094 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1098 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1100 sector_t sector = bio->bi_sector + bio_sectors(bio);
1102 return elv_rb_find(&cfqq->sort_list, sector);
1108 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1110 struct cfq_data *cfqd = q->elevator->elevator_data;
1112 cfqd->rq_in_driver[rq_is_sync(rq)]++;
1113 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1114 rq_in_driver(cfqd));
1116 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1119 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1121 struct cfq_data *cfqd = q->elevator->elevator_data;
1122 const int sync = rq_is_sync(rq);
1124 WARN_ON(!cfqd->rq_in_driver[sync]);
1125 cfqd->rq_in_driver[sync]--;
1126 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1127 rq_in_driver(cfqd));
1130 static void cfq_remove_request(struct request *rq)
1132 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1134 if (cfqq->next_rq == rq)
1135 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1137 list_del_init(&rq->queuelist);
1140 cfqq->cfqd->rq_queued--;
1141 if (rq_is_meta(rq)) {
1142 WARN_ON(!cfqq->meta_pending);
1143 cfqq->meta_pending--;
1147 static int cfq_merge(struct request_queue *q, struct request **req,
1150 struct cfq_data *cfqd = q->elevator->elevator_data;
1151 struct request *__rq;
1153 __rq = cfq_find_rq_fmerge(cfqd, bio);
1154 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1156 return ELEVATOR_FRONT_MERGE;
1159 return ELEVATOR_NO_MERGE;
1162 static void cfq_merged_request(struct request_queue *q, struct request *req,
1165 if (type == ELEVATOR_FRONT_MERGE) {
1166 struct cfq_queue *cfqq = RQ_CFQQ(req);
1168 cfq_reposition_rq_rb(cfqq, req);
1173 cfq_merged_requests(struct request_queue *q, struct request *rq,
1174 struct request *next)
1176 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1178 * reposition in fifo if next is older than rq
1180 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1181 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1182 list_move(&rq->queuelist, &next->queuelist);
1183 rq_set_fifo_time(rq, rq_fifo_time(next));
1186 if (cfqq->next_rq == next)
1188 cfq_remove_request(next);
1191 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1194 struct cfq_data *cfqd = q->elevator->elevator_data;
1195 struct cfq_io_context *cic;
1196 struct cfq_queue *cfqq;
1199 * Disallow merge of a sync bio into an async request.
1201 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1205 * Lookup the cfqq that this bio will be queued with. Allow
1206 * merge only if rq is queued there.
1208 cic = cfq_cic_lookup(cfqd, current->io_context);
1212 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1213 return cfqq == RQ_CFQQ(rq);
1216 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1217 struct cfq_queue *cfqq)
1220 cfq_log_cfqq(cfqd, cfqq, "set_active");
1221 cfqq->slice_end = 0;
1222 cfqq->slice_dispatch = 0;
1224 cfq_clear_cfqq_wait_request(cfqq);
1225 cfq_clear_cfqq_must_dispatch(cfqq);
1226 cfq_clear_cfqq_must_alloc_slice(cfqq);
1227 cfq_clear_cfqq_fifo_expire(cfqq);
1228 cfq_mark_cfqq_slice_new(cfqq);
1230 del_timer(&cfqd->idle_slice_timer);
1233 cfqd->active_queue = cfqq;
1237 * current cfqq expired its slice (or was too idle), select new one
1240 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1243 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1245 if (cfq_cfqq_wait_request(cfqq))
1246 del_timer(&cfqd->idle_slice_timer);
1248 cfq_clear_cfqq_wait_request(cfqq);
1251 * store what was left of this slice, if the queue idled/timed out
1253 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
1254 cfqq->slice_resid = cfqq->slice_end - jiffies;
1255 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1258 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1259 cfq_del_cfqq_rr(cfqd, cfqq);
1261 cfq_resort_rr_list(cfqd, cfqq);
1263 if (cfqq == cfqd->active_queue)
1264 cfqd->active_queue = NULL;
1266 if (cfqd->active_cic) {
1267 put_io_context(cfqd->active_cic->ioc);
1268 cfqd->active_cic = NULL;
1272 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1274 struct cfq_queue *cfqq = cfqd->active_queue;
1277 __cfq_slice_expired(cfqd, cfqq, timed_out);
1281 * Get next queue for service. Unless we have a queue preemption,
1282 * we'll simply select the first cfqq in the service tree.
1284 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1286 struct cfq_rb_root *service_tree =
1287 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1288 cfqd->serving_type, cfqd);
1290 if (!cfqd->rq_queued)
1293 /* There is nothing to dispatch */
1296 if (RB_EMPTY_ROOT(&service_tree->rb))
1298 return cfq_rb_first(service_tree);
1301 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1303 struct cfq_group *cfqg = &cfqd->root_group;
1304 struct cfq_queue *cfqq;
1306 struct cfq_rb_root *st;
1308 if (!cfqd->rq_queued)
1311 for_each_cfqg_st(cfqg, i, j, st)
1312 if ((cfqq = cfq_rb_first(st)) != NULL)
1318 * Get and set a new active queue for service.
1320 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1321 struct cfq_queue *cfqq)
1324 cfqq = cfq_get_next_queue(cfqd);
1326 __cfq_set_active_queue(cfqd, cfqq);
1330 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1333 if (blk_rq_pos(rq) >= cfqd->last_position)
1334 return blk_rq_pos(rq) - cfqd->last_position;
1336 return cfqd->last_position - blk_rq_pos(rq);
1339 #define CFQQ_SEEK_THR 8 * 1024
1340 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1342 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1345 sector_t sdist = cfqq->seek_mean;
1347 if (!sample_valid(cfqq->seek_samples))
1348 sdist = CFQQ_SEEK_THR;
1350 return cfq_dist_from_last(cfqd, rq) <= sdist;
1353 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1354 struct cfq_queue *cur_cfqq)
1356 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1357 struct rb_node *parent, *node;
1358 struct cfq_queue *__cfqq;
1359 sector_t sector = cfqd->last_position;
1361 if (RB_EMPTY_ROOT(root))
1365 * First, if we find a request starting at the end of the last
1366 * request, choose it.
1368 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1373 * If the exact sector wasn't found, the parent of the NULL leaf
1374 * will contain the closest sector.
1376 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1377 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1380 if (blk_rq_pos(__cfqq->next_rq) < sector)
1381 node = rb_next(&__cfqq->p_node);
1383 node = rb_prev(&__cfqq->p_node);
1387 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1388 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1396 * cur_cfqq - passed in so that we don't decide that the current queue is
1397 * closely cooperating with itself.
1399 * So, basically we're assuming that that cur_cfqq has dispatched at least
1400 * one request, and that cfqd->last_position reflects a position on the disk
1401 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1404 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1405 struct cfq_queue *cur_cfqq)
1407 struct cfq_queue *cfqq;
1409 if (!cfq_cfqq_sync(cur_cfqq))
1411 if (CFQQ_SEEKY(cur_cfqq))
1415 * We should notice if some of the queues are cooperating, eg
1416 * working closely on the same area of the disk. In that case,
1417 * we can group them together and don't waste time idling.
1419 cfqq = cfqq_close(cfqd, cur_cfqq);
1424 * It only makes sense to merge sync queues.
1426 if (!cfq_cfqq_sync(cfqq))
1428 if (CFQQ_SEEKY(cfqq))
1432 * Do not merge queues of different priority classes
1434 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1441 * Determine whether we should enforce idle window for this queue.
1444 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1446 enum wl_prio_t prio = cfqq_prio(cfqq);
1447 struct cfq_rb_root *service_tree = cfqq->service_tree;
1449 BUG_ON(!service_tree);
1450 BUG_ON(!service_tree->count);
1452 /* We never do for idle class queues. */
1453 if (prio == IDLE_WORKLOAD)
1456 /* We do for queues that were marked with idle window flag. */
1457 if (cfq_cfqq_idle_window(cfqq))
1461 * Otherwise, we do only if they are the last ones
1462 * in their service tree.
1464 return service_tree->count == 1;
1467 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1469 struct cfq_queue *cfqq = cfqd->active_queue;
1470 struct cfq_io_context *cic;
1474 * SSD device without seek penalty, disable idling. But only do so
1475 * for devices that support queuing, otherwise we still have a problem
1476 * with sync vs async workloads.
1478 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1481 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1482 WARN_ON(cfq_cfqq_slice_new(cfqq));
1485 * idle is disabled, either manually or by past process history
1487 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
1491 * still active requests from this queue, don't idle
1493 if (cfqq->dispatched)
1497 * task has exited, don't wait
1499 cic = cfqd->active_cic;
1500 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1504 * If our average think time is larger than the remaining time
1505 * slice, then don't idle. This avoids overrunning the allotted
1508 if (sample_valid(cic->ttime_samples) &&
1509 (cfqq->slice_end - jiffies < cic->ttime_mean))
1512 cfq_mark_cfqq_wait_request(cfqq);
1514 sl = cfqd->cfq_slice_idle;
1516 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1517 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1521 * Move request from internal lists to the request queue dispatch list.
1523 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1525 struct cfq_data *cfqd = q->elevator->elevator_data;
1526 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1528 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1530 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1531 cfq_remove_request(rq);
1533 elv_dispatch_sort(q, rq);
1535 if (cfq_cfqq_sync(cfqq))
1536 cfqd->sync_flight++;
1540 * return expired entry, or NULL to just start from scratch in rbtree
1542 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1544 struct request *rq = NULL;
1546 if (cfq_cfqq_fifo_expire(cfqq))
1549 cfq_mark_cfqq_fifo_expire(cfqq);
1551 if (list_empty(&cfqq->fifo))
1554 rq = rq_entry_fifo(cfqq->fifo.next);
1555 if (time_before(jiffies, rq_fifo_time(rq)))
1558 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1563 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1565 const int base_rq = cfqd->cfq_slice_async_rq;
1567 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1569 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1573 * Must be called with the queue_lock held.
1575 static int cfqq_process_refs(struct cfq_queue *cfqq)
1577 int process_refs, io_refs;
1579 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
1580 process_refs = atomic_read(&cfqq->ref) - io_refs;
1581 BUG_ON(process_refs < 0);
1582 return process_refs;
1585 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
1587 int process_refs, new_process_refs;
1588 struct cfq_queue *__cfqq;
1590 /* Avoid a circular list and skip interim queue merges */
1591 while ((__cfqq = new_cfqq->new_cfqq)) {
1597 process_refs = cfqq_process_refs(cfqq);
1599 * If the process for the cfqq has gone away, there is no
1600 * sense in merging the queues.
1602 if (process_refs == 0)
1606 * Merge in the direction of the lesser amount of work.
1608 new_process_refs = cfqq_process_refs(new_cfqq);
1609 if (new_process_refs >= process_refs) {
1610 cfqq->new_cfqq = new_cfqq;
1611 atomic_add(process_refs, &new_cfqq->ref);
1613 new_cfqq->new_cfqq = cfqq;
1614 atomic_add(new_process_refs, &cfqq->ref);
1618 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
1619 struct cfq_group *cfqg, enum wl_prio_t prio,
1622 struct cfq_queue *queue;
1624 bool key_valid = false;
1625 unsigned long lowest_key = 0;
1626 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
1630 * When priorities switched, we prefer starting
1631 * from SYNC_NOIDLE (first choice), or just SYNC
1634 if (service_tree_for(cfqg, prio, cur_best, cfqd)->count)
1636 cur_best = SYNC_WORKLOAD;
1637 if (service_tree_for(cfqg, prio, cur_best, cfqd)->count)
1640 return ASYNC_WORKLOAD;
1643 for (i = 0; i < 3; ++i) {
1644 /* otherwise, select the one with lowest rb_key */
1645 queue = cfq_rb_first(service_tree_for(cfqg, prio, i, cfqd));
1647 (!key_valid || time_before(queue->rb_key, lowest_key))) {
1648 lowest_key = queue->rb_key;
1657 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
1659 enum wl_prio_t previous_prio = cfqd->serving_prio;
1663 struct cfq_rb_root *st;
1664 unsigned group_slice;
1667 cfqd->serving_prio = IDLE_WORKLOAD;
1668 cfqd->workload_expires = jiffies + 1;
1672 /* Choose next priority. RT > BE > IDLE */
1673 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
1674 cfqd->serving_prio = RT_WORKLOAD;
1675 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
1676 cfqd->serving_prio = BE_WORKLOAD;
1678 cfqd->serving_prio = IDLE_WORKLOAD;
1679 cfqd->workload_expires = jiffies + 1;
1684 * For RT and BE, we have to choose also the type
1685 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
1688 prio_changed = (cfqd->serving_prio != previous_prio);
1689 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
1694 * If priority didn't change, check workload expiration,
1695 * and that we still have other queues ready
1697 if (!prio_changed && count &&
1698 !time_after(jiffies, cfqd->workload_expires))
1701 /* otherwise select new workload type */
1702 cfqd->serving_type =
1703 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio, prio_changed);
1704 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
1709 * the workload slice is computed as a fraction of target latency
1710 * proportional to the number of queues in that workload, over
1711 * all the queues in the same priority class
1713 group_slice = cfq_group_slice(cfqd, cfqg);
1715 slice = group_slice * count /
1716 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
1717 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
1719 if (cfqd->serving_type == ASYNC_WORKLOAD)
1720 /* async workload slice is scaled down according to
1721 * the sync/async slice ratio. */
1722 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
1724 /* sync workload slice is at least 2 * cfq_slice_idle */
1725 slice = max(slice, 2 * cfqd->cfq_slice_idle);
1727 slice = max_t(unsigned, slice, CFQ_MIN_TT);
1728 cfqd->workload_expires = jiffies + slice;
1729 cfqd->noidle_tree_requires_idle = false;
1732 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
1734 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1735 struct cfq_group *cfqg;
1737 if (RB_EMPTY_ROOT(&st->rb))
1739 cfqg = cfq_rb_first_group(st);
1740 st->active = &cfqg->rb_node;
1741 update_min_vdisktime(st);
1745 static void cfq_choose_cfqg(struct cfq_data *cfqd)
1747 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
1749 cfqd->serving_group = cfqg;
1750 choose_service_tree(cfqd, cfqg);
1754 * Select a queue for service. If we have a current active queue,
1755 * check whether to continue servicing it, or retrieve and set a new one.
1757 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1759 struct cfq_queue *cfqq, *new_cfqq = NULL;
1761 cfqq = cfqd->active_queue;
1765 if (!cfqd->rq_queued)
1768 * The active queue has run out of time, expire it and select new.
1770 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1774 * The active queue has requests and isn't expired, allow it to
1777 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1781 * If another queue has a request waiting within our mean seek
1782 * distance, let it run. The expire code will check for close
1783 * cooperators and put the close queue at the front of the service
1784 * tree. If possible, merge the expiring queue with the new cfqq.
1786 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
1788 if (!cfqq->new_cfqq)
1789 cfq_setup_merge(cfqq, new_cfqq);
1794 * No requests pending. If the active queue still has requests in
1795 * flight or is idling for a new request, allow either of these
1796 * conditions to happen (or time out) before selecting a new queue.
1798 if (timer_pending(&cfqd->idle_slice_timer) ||
1799 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
1805 cfq_slice_expired(cfqd, 0);
1808 * Current queue expired. Check if we have to switch to a new
1812 cfq_choose_cfqg(cfqd);
1814 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1819 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1823 while (cfqq->next_rq) {
1824 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1828 BUG_ON(!list_empty(&cfqq->fifo));
1830 /* By default cfqq is not expired if it is empty. Do it explicitly */
1831 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
1836 * Drain our current requests. Used for barriers and when switching
1837 * io schedulers on-the-fly.
1839 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1841 struct cfq_queue *cfqq;
1844 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL)
1845 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1847 cfq_slice_expired(cfqd, 0);
1848 BUG_ON(cfqd->busy_queues);
1850 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1854 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1856 unsigned int max_dispatch;
1859 * Drain async requests before we start sync IO
1861 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
1865 * If this is an async queue and we have sync IO in flight, let it wait
1867 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1870 max_dispatch = cfqd->cfq_quantum;
1871 if (cfq_class_idle(cfqq))
1875 * Does this cfqq already have too much IO in flight?
1877 if (cfqq->dispatched >= max_dispatch) {
1879 * idle queue must always only have a single IO in flight
1881 if (cfq_class_idle(cfqq))
1885 * We have other queues, don't allow more IO from this one
1887 if (cfqd->busy_queues > 1)
1891 * Sole queue user, no limit
1897 * Async queues must wait a bit before being allowed dispatch.
1898 * We also ramp up the dispatch depth gradually for async IO,
1899 * based on the last sync IO we serviced
1901 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
1902 unsigned long last_sync = jiffies - cfqd->last_end_sync_rq;
1905 depth = last_sync / cfqd->cfq_slice[1];
1906 if (!depth && !cfqq->dispatched)
1908 if (depth < max_dispatch)
1909 max_dispatch = depth;
1913 * If we're below the current max, allow a dispatch
1915 return cfqq->dispatched < max_dispatch;
1919 * Dispatch a request from cfqq, moving them to the request queue
1922 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1926 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1928 if (!cfq_may_dispatch(cfqd, cfqq))
1932 * follow expired path, else get first next available
1934 rq = cfq_check_fifo(cfqq);
1939 * insert request into driver dispatch list
1941 cfq_dispatch_insert(cfqd->queue, rq);
1943 if (!cfqd->active_cic) {
1944 struct cfq_io_context *cic = RQ_CIC(rq);
1946 atomic_long_inc(&cic->ioc->refcount);
1947 cfqd->active_cic = cic;
1954 * Find the cfqq that we need to service and move a request from that to the
1957 static int cfq_dispatch_requests(struct request_queue *q, int force)
1959 struct cfq_data *cfqd = q->elevator->elevator_data;
1960 struct cfq_queue *cfqq;
1962 if (!cfqd->busy_queues)
1965 if (unlikely(force))
1966 return cfq_forced_dispatch(cfqd);
1968 cfqq = cfq_select_queue(cfqd);
1973 * Dispatch a request from this cfqq, if it is allowed
1975 if (!cfq_dispatch_request(cfqd, cfqq))
1978 cfqq->slice_dispatch++;
1979 cfq_clear_cfqq_must_dispatch(cfqq);
1982 * expire an async queue immediately if it has used up its slice. idle
1983 * queue always expire after 1 dispatch round.
1985 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1986 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1987 cfq_class_idle(cfqq))) {
1988 cfqq->slice_end = jiffies + 1;
1989 cfq_slice_expired(cfqd, 0);
1992 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
1997 * task holds one reference to the queue, dropped when task exits. each rq
1998 * in-flight on this queue also holds a reference, dropped when rq is freed.
2000 * queue lock must be held here.
2002 static void cfq_put_queue(struct cfq_queue *cfqq)
2004 struct cfq_data *cfqd = cfqq->cfqd;
2006 BUG_ON(atomic_read(&cfqq->ref) <= 0);
2008 if (!atomic_dec_and_test(&cfqq->ref))
2011 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2012 BUG_ON(rb_first(&cfqq->sort_list));
2013 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2015 if (unlikely(cfqd->active_queue == cfqq)) {
2016 __cfq_slice_expired(cfqd, cfqq, 0);
2017 cfq_schedule_dispatch(cfqd);
2020 BUG_ON(cfq_cfqq_on_rr(cfqq));
2021 kmem_cache_free(cfq_pool, cfqq);
2025 * Must always be called with the rcu_read_lock() held
2028 __call_for_each_cic(struct io_context *ioc,
2029 void (*func)(struct io_context *, struct cfq_io_context *))
2031 struct cfq_io_context *cic;
2032 struct hlist_node *n;
2034 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2039 * Call func for each cic attached to this ioc.
2042 call_for_each_cic(struct io_context *ioc,
2043 void (*func)(struct io_context *, struct cfq_io_context *))
2046 __call_for_each_cic(ioc, func);
2050 static void cfq_cic_free_rcu(struct rcu_head *head)
2052 struct cfq_io_context *cic;
2054 cic = container_of(head, struct cfq_io_context, rcu_head);
2056 kmem_cache_free(cfq_ioc_pool, cic);
2057 elv_ioc_count_dec(cfq_ioc_count);
2061 * CFQ scheduler is exiting, grab exit lock and check
2062 * the pending io context count. If it hits zero,
2063 * complete ioc_gone and set it back to NULL
2065 spin_lock(&ioc_gone_lock);
2066 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2070 spin_unlock(&ioc_gone_lock);
2074 static void cfq_cic_free(struct cfq_io_context *cic)
2076 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2079 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2081 unsigned long flags;
2083 BUG_ON(!cic->dead_key);
2085 spin_lock_irqsave(&ioc->lock, flags);
2086 radix_tree_delete(&ioc->radix_root, cic->dead_key);
2087 hlist_del_rcu(&cic->cic_list);
2088 spin_unlock_irqrestore(&ioc->lock, flags);
2094 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2095 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2096 * and ->trim() which is called with the task lock held
2098 static void cfq_free_io_context(struct io_context *ioc)
2101 * ioc->refcount is zero here, or we are called from elv_unregister(),
2102 * so no more cic's are allowed to be linked into this ioc. So it
2103 * should be ok to iterate over the known list, we will see all cic's
2104 * since no new ones are added.
2106 __call_for_each_cic(ioc, cic_free_func);
2109 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2111 struct cfq_queue *__cfqq, *next;
2113 if (unlikely(cfqq == cfqd->active_queue)) {
2114 __cfq_slice_expired(cfqd, cfqq, 0);
2115 cfq_schedule_dispatch(cfqd);
2119 * If this queue was scheduled to merge with another queue, be
2120 * sure to drop the reference taken on that queue (and others in
2121 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2123 __cfqq = cfqq->new_cfqq;
2125 if (__cfqq == cfqq) {
2126 WARN(1, "cfqq->new_cfqq loop detected\n");
2129 next = __cfqq->new_cfqq;
2130 cfq_put_queue(__cfqq);
2134 cfq_put_queue(cfqq);
2137 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2138 struct cfq_io_context *cic)
2140 struct io_context *ioc = cic->ioc;
2142 list_del_init(&cic->queue_list);
2145 * Make sure key == NULL is seen for dead queues
2148 cic->dead_key = (unsigned long) cic->key;
2151 if (ioc->ioc_data == cic)
2152 rcu_assign_pointer(ioc->ioc_data, NULL);
2154 if (cic->cfqq[BLK_RW_ASYNC]) {
2155 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2156 cic->cfqq[BLK_RW_ASYNC] = NULL;
2159 if (cic->cfqq[BLK_RW_SYNC]) {
2160 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2161 cic->cfqq[BLK_RW_SYNC] = NULL;
2165 static void cfq_exit_single_io_context(struct io_context *ioc,
2166 struct cfq_io_context *cic)
2168 struct cfq_data *cfqd = cic->key;
2171 struct request_queue *q = cfqd->queue;
2172 unsigned long flags;
2174 spin_lock_irqsave(q->queue_lock, flags);
2177 * Ensure we get a fresh copy of the ->key to prevent
2178 * race between exiting task and queue
2180 smp_read_barrier_depends();
2182 __cfq_exit_single_io_context(cfqd, cic);
2184 spin_unlock_irqrestore(q->queue_lock, flags);
2189 * The process that ioc belongs to has exited, we need to clean up
2190 * and put the internal structures we have that belongs to that process.
2192 static void cfq_exit_io_context(struct io_context *ioc)
2194 call_for_each_cic(ioc, cfq_exit_single_io_context);
2197 static struct cfq_io_context *
2198 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2200 struct cfq_io_context *cic;
2202 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2205 cic->last_end_request = jiffies;
2206 INIT_LIST_HEAD(&cic->queue_list);
2207 INIT_HLIST_NODE(&cic->cic_list);
2208 cic->dtor = cfq_free_io_context;
2209 cic->exit = cfq_exit_io_context;
2210 elv_ioc_count_inc(cfq_ioc_count);
2216 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2218 struct task_struct *tsk = current;
2221 if (!cfq_cfqq_prio_changed(cfqq))
2224 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2225 switch (ioprio_class) {
2227 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2228 case IOPRIO_CLASS_NONE:
2230 * no prio set, inherit CPU scheduling settings
2232 cfqq->ioprio = task_nice_ioprio(tsk);
2233 cfqq->ioprio_class = task_nice_ioclass(tsk);
2235 case IOPRIO_CLASS_RT:
2236 cfqq->ioprio = task_ioprio(ioc);
2237 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2239 case IOPRIO_CLASS_BE:
2240 cfqq->ioprio = task_ioprio(ioc);
2241 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2243 case IOPRIO_CLASS_IDLE:
2244 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2246 cfq_clear_cfqq_idle_window(cfqq);
2251 * keep track of original prio settings in case we have to temporarily
2252 * elevate the priority of this queue
2254 cfqq->org_ioprio = cfqq->ioprio;
2255 cfqq->org_ioprio_class = cfqq->ioprio_class;
2256 cfq_clear_cfqq_prio_changed(cfqq);
2259 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2261 struct cfq_data *cfqd = cic->key;
2262 struct cfq_queue *cfqq;
2263 unsigned long flags;
2265 if (unlikely(!cfqd))
2268 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2270 cfqq = cic->cfqq[BLK_RW_ASYNC];
2272 struct cfq_queue *new_cfqq;
2273 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2276 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2277 cfq_put_queue(cfqq);
2281 cfqq = cic->cfqq[BLK_RW_SYNC];
2283 cfq_mark_cfqq_prio_changed(cfqq);
2285 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2288 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2290 call_for_each_cic(ioc, changed_ioprio);
2291 ioc->ioprio_changed = 0;
2294 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2295 pid_t pid, bool is_sync)
2297 RB_CLEAR_NODE(&cfqq->rb_node);
2298 RB_CLEAR_NODE(&cfqq->p_node);
2299 INIT_LIST_HEAD(&cfqq->fifo);
2301 atomic_set(&cfqq->ref, 0);
2304 cfq_mark_cfqq_prio_changed(cfqq);
2307 if (!cfq_class_idle(cfqq))
2308 cfq_mark_cfqq_idle_window(cfqq);
2309 cfq_mark_cfqq_sync(cfqq);
2314 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
2319 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
2321 return &cfqd->root_group;
2324 static struct cfq_queue *
2325 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2326 struct io_context *ioc, gfp_t gfp_mask)
2328 struct cfq_queue *cfqq, *new_cfqq = NULL;
2329 struct cfq_io_context *cic;
2330 struct cfq_group *cfqg;
2333 cfqg = cfq_get_cfqg(cfqd, 1);
2334 cic = cfq_cic_lookup(cfqd, ioc);
2335 /* cic always exists here */
2336 cfqq = cic_to_cfqq(cic, is_sync);
2339 * Always try a new alloc if we fell back to the OOM cfqq
2340 * originally, since it should just be a temporary situation.
2342 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2347 } else if (gfp_mask & __GFP_WAIT) {
2348 spin_unlock_irq(cfqd->queue->queue_lock);
2349 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2350 gfp_mask | __GFP_ZERO,
2352 spin_lock_irq(cfqd->queue->queue_lock);
2356 cfqq = kmem_cache_alloc_node(cfq_pool,
2357 gfp_mask | __GFP_ZERO,
2362 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2363 cfq_init_prio_data(cfqq, ioc);
2364 cfq_link_cfqq_cfqg(cfqq, cfqg);
2365 cfq_log_cfqq(cfqd, cfqq, "alloced");
2367 cfqq = &cfqd->oom_cfqq;
2371 kmem_cache_free(cfq_pool, new_cfqq);
2376 static struct cfq_queue **
2377 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2379 switch (ioprio_class) {
2380 case IOPRIO_CLASS_RT:
2381 return &cfqd->async_cfqq[0][ioprio];
2382 case IOPRIO_CLASS_BE:
2383 return &cfqd->async_cfqq[1][ioprio];
2384 case IOPRIO_CLASS_IDLE:
2385 return &cfqd->async_idle_cfqq;
2391 static struct cfq_queue *
2392 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2395 const int ioprio = task_ioprio(ioc);
2396 const int ioprio_class = task_ioprio_class(ioc);
2397 struct cfq_queue **async_cfqq = NULL;
2398 struct cfq_queue *cfqq = NULL;
2401 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2406 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2409 * pin the queue now that it's allocated, scheduler exit will prune it
2411 if (!is_sync && !(*async_cfqq)) {
2412 atomic_inc(&cfqq->ref);
2416 atomic_inc(&cfqq->ref);
2421 * We drop cfq io contexts lazily, so we may find a dead one.
2424 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2425 struct cfq_io_context *cic)
2427 unsigned long flags;
2429 WARN_ON(!list_empty(&cic->queue_list));
2431 spin_lock_irqsave(&ioc->lock, flags);
2433 BUG_ON(ioc->ioc_data == cic);
2435 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
2436 hlist_del_rcu(&cic->cic_list);
2437 spin_unlock_irqrestore(&ioc->lock, flags);
2442 static struct cfq_io_context *
2443 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
2445 struct cfq_io_context *cic;
2446 unsigned long flags;
2455 * we maintain a last-hit cache, to avoid browsing over the tree
2457 cic = rcu_dereference(ioc->ioc_data);
2458 if (cic && cic->key == cfqd) {
2464 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
2468 /* ->key must be copied to avoid race with cfq_exit_queue() */
2471 cfq_drop_dead_cic(cfqd, ioc, cic);
2476 spin_lock_irqsave(&ioc->lock, flags);
2477 rcu_assign_pointer(ioc->ioc_data, cic);
2478 spin_unlock_irqrestore(&ioc->lock, flags);
2486 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2487 * the process specific cfq io context when entered from the block layer.
2488 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2490 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
2491 struct cfq_io_context *cic, gfp_t gfp_mask)
2493 unsigned long flags;
2496 ret = radix_tree_preload(gfp_mask);
2501 spin_lock_irqsave(&ioc->lock, flags);
2502 ret = radix_tree_insert(&ioc->radix_root,
2503 (unsigned long) cfqd, cic);
2505 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
2506 spin_unlock_irqrestore(&ioc->lock, flags);
2508 radix_tree_preload_end();
2511 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2512 list_add(&cic->queue_list, &cfqd->cic_list);
2513 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2518 printk(KERN_ERR "cfq: cic link failed!\n");
2524 * Setup general io context and cfq io context. There can be several cfq
2525 * io contexts per general io context, if this process is doing io to more
2526 * than one device managed by cfq.
2528 static struct cfq_io_context *
2529 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2531 struct io_context *ioc = NULL;
2532 struct cfq_io_context *cic;
2534 might_sleep_if(gfp_mask & __GFP_WAIT);
2536 ioc = get_io_context(gfp_mask, cfqd->queue->node);
2540 cic = cfq_cic_lookup(cfqd, ioc);
2544 cic = cfq_alloc_io_context(cfqd, gfp_mask);
2548 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
2552 smp_read_barrier_depends();
2553 if (unlikely(ioc->ioprio_changed))
2554 cfq_ioc_set_ioprio(ioc);
2560 put_io_context(ioc);
2565 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
2567 unsigned long elapsed = jiffies - cic->last_end_request;
2568 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
2570 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
2571 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
2572 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
2576 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2582 if (!cfqq->last_request_pos)
2584 else if (cfqq->last_request_pos < blk_rq_pos(rq))
2585 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
2587 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
2590 * Don't allow the seek distance to get too large from the
2591 * odd fragment, pagein, etc
2593 if (cfqq->seek_samples <= 60) /* second&third seek */
2594 sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024);
2596 sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64);
2598 cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8;
2599 cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8;
2600 total = cfqq->seek_total + (cfqq->seek_samples/2);
2601 do_div(total, cfqq->seek_samples);
2602 cfqq->seek_mean = (sector_t)total;
2605 * If this cfqq is shared between multiple processes, check to
2606 * make sure that those processes are still issuing I/Os within
2607 * the mean seek distance. If not, it may be time to break the
2608 * queues apart again.
2610 if (cfq_cfqq_coop(cfqq)) {
2611 if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start)
2612 cfqq->seeky_start = jiffies;
2613 else if (!CFQQ_SEEKY(cfqq))
2614 cfqq->seeky_start = 0;
2619 * Disable idle window if the process thinks too long or seeks so much that
2623 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2624 struct cfq_io_context *cic)
2626 int old_idle, enable_idle;
2629 * Don't idle for async or idle io prio class
2631 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
2634 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
2636 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
2637 cfq_mark_cfqq_deep(cfqq);
2639 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
2640 (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples)
2641 && CFQQ_SEEKY(cfqq)))
2643 else if (sample_valid(cic->ttime_samples)) {
2644 if (cic->ttime_mean > cfqd->cfq_slice_idle)
2650 if (old_idle != enable_idle) {
2651 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
2653 cfq_mark_cfqq_idle_window(cfqq);
2655 cfq_clear_cfqq_idle_window(cfqq);
2660 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2661 * no or if we aren't sure, a 1 will cause a preempt.
2664 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
2667 struct cfq_queue *cfqq;
2669 cfqq = cfqd->active_queue;
2673 if (cfq_slice_used(cfqq))
2676 if (cfq_class_idle(new_cfqq))
2679 if (cfq_class_idle(cfqq))
2682 /* Allow preemption only if we are idling on sync-noidle tree */
2683 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
2684 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
2685 new_cfqq->service_tree->count == 2 &&
2686 RB_EMPTY_ROOT(&cfqq->sort_list))
2690 * if the new request is sync, but the currently running queue is
2691 * not, let the sync request have priority.
2693 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2697 * So both queues are sync. Let the new request get disk time if
2698 * it's a metadata request and the current queue is doing regular IO.
2700 if (rq_is_meta(rq) && !cfqq->meta_pending)
2704 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2706 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2709 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2713 * if this request is as-good as one we would expect from the
2714 * current cfqq, let it preempt
2716 if (cfq_rq_close(cfqd, cfqq, rq))
2723 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2724 * let it have half of its nominal slice.
2726 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2728 cfq_log_cfqq(cfqd, cfqq, "preempt");
2729 cfq_slice_expired(cfqd, 1);
2732 * Put the new queue at the front of the of the current list,
2733 * so we know that it will be selected next.
2735 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2737 cfq_service_tree_add(cfqd, cfqq, 1);
2739 cfqq->slice_end = 0;
2740 cfq_mark_cfqq_slice_new(cfqq);
2744 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2745 * something we should do about it
2748 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2751 struct cfq_io_context *cic = RQ_CIC(rq);
2755 cfqq->meta_pending++;
2757 cfq_update_io_thinktime(cfqd, cic);
2758 cfq_update_io_seektime(cfqd, cfqq, rq);
2759 cfq_update_idle_window(cfqd, cfqq, cic);
2761 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2763 if (cfqq == cfqd->active_queue) {
2765 * Remember that we saw a request from this process, but
2766 * don't start queuing just yet. Otherwise we risk seeing lots
2767 * of tiny requests, because we disrupt the normal plugging
2768 * and merging. If the request is already larger than a single
2769 * page, let it rip immediately. For that case we assume that
2770 * merging is already done. Ditto for a busy system that
2771 * has other work pending, don't risk delaying until the
2772 * idle timer unplug to continue working.
2774 if (cfq_cfqq_wait_request(cfqq)) {
2775 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2776 cfqd->busy_queues > 1) {
2777 del_timer(&cfqd->idle_slice_timer);
2778 __blk_run_queue(cfqd->queue);
2780 cfq_mark_cfqq_must_dispatch(cfqq);
2782 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2784 * not the active queue - expire current slice if it is
2785 * idle and has expired it's mean thinktime or this new queue
2786 * has some old slice time left and is of higher priority or
2787 * this new queue is RT and the current one is BE
2789 cfq_preempt_queue(cfqd, cfqq);
2790 __blk_run_queue(cfqd->queue);
2794 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2796 struct cfq_data *cfqd = q->elevator->elevator_data;
2797 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2799 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2800 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2802 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
2803 list_add_tail(&rq->queuelist, &cfqq->fifo);
2806 cfq_rq_enqueued(cfqd, cfqq, rq);
2810 * Update hw_tag based on peak queue depth over 50 samples under
2813 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2815 struct cfq_queue *cfqq = cfqd->active_queue;
2817 if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth)
2818 cfqd->hw_tag_est_depth = rq_in_driver(cfqd);
2820 if (cfqd->hw_tag == 1)
2823 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2824 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
2828 * If active queue hasn't enough requests and can idle, cfq might not
2829 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
2832 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
2833 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
2834 CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN)
2837 if (cfqd->hw_tag_samples++ < 50)
2840 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
2846 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2848 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2849 struct cfq_data *cfqd = cfqq->cfqd;
2850 const int sync = rq_is_sync(rq);
2854 cfq_log_cfqq(cfqd, cfqq, "complete");
2856 cfq_update_hw_tag(cfqd);
2858 WARN_ON(!cfqd->rq_in_driver[sync]);
2859 WARN_ON(!cfqq->dispatched);
2860 cfqd->rq_in_driver[sync]--;
2863 if (cfq_cfqq_sync(cfqq))
2864 cfqd->sync_flight--;
2867 RQ_CIC(rq)->last_end_request = now;
2868 cfqd->last_end_sync_rq = now;
2872 * If this is the active queue, check if it needs to be expired,
2873 * or if we want to idle in case it has no pending requests.
2875 if (cfqd->active_queue == cfqq) {
2876 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2878 if (cfq_cfqq_slice_new(cfqq)) {
2879 cfq_set_prio_slice(cfqd, cfqq);
2880 cfq_clear_cfqq_slice_new(cfqq);
2883 * Idling is not enabled on:
2885 * - idle-priority queues
2887 * - queues with still some requests queued
2888 * - when there is a close cooperator
2890 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2891 cfq_slice_expired(cfqd, 1);
2892 else if (sync && cfqq_empty &&
2893 !cfq_close_cooperator(cfqd, cfqq)) {
2894 cfqd->noidle_tree_requires_idle |= !rq_noidle(rq);
2896 * Idling is enabled for SYNC_WORKLOAD.
2897 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
2898 * only if we processed at least one !rq_noidle request
2900 if (cfqd->serving_type == SYNC_WORKLOAD
2901 || cfqd->noidle_tree_requires_idle)
2902 cfq_arm_slice_timer(cfqd);
2906 if (!rq_in_driver(cfqd))
2907 cfq_schedule_dispatch(cfqd);
2911 * we temporarily boost lower priority queues if they are holding fs exclusive
2912 * resources. they are boosted to normal prio (CLASS_BE/4)
2914 static void cfq_prio_boost(struct cfq_queue *cfqq)
2916 if (has_fs_excl()) {
2918 * boost idle prio on transactions that would lock out other
2919 * users of the filesystem
2921 if (cfq_class_idle(cfqq))
2922 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2923 if (cfqq->ioprio > IOPRIO_NORM)
2924 cfqq->ioprio = IOPRIO_NORM;
2927 * unboost the queue (if needed)
2929 cfqq->ioprio_class = cfqq->org_ioprio_class;
2930 cfqq->ioprio = cfqq->org_ioprio;
2934 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2936 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
2937 cfq_mark_cfqq_must_alloc_slice(cfqq);
2938 return ELV_MQUEUE_MUST;
2941 return ELV_MQUEUE_MAY;
2944 static int cfq_may_queue(struct request_queue *q, int rw)
2946 struct cfq_data *cfqd = q->elevator->elevator_data;
2947 struct task_struct *tsk = current;
2948 struct cfq_io_context *cic;
2949 struct cfq_queue *cfqq;
2952 * don't force setup of a queue from here, as a call to may_queue
2953 * does not necessarily imply that a request actually will be queued.
2954 * so just lookup a possibly existing queue, or return 'may queue'
2957 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2959 return ELV_MQUEUE_MAY;
2961 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2963 cfq_init_prio_data(cfqq, cic->ioc);
2964 cfq_prio_boost(cfqq);
2966 return __cfq_may_queue(cfqq);
2969 return ELV_MQUEUE_MAY;
2973 * queue lock held here
2975 static void cfq_put_request(struct request *rq)
2977 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2980 const int rw = rq_data_dir(rq);
2982 BUG_ON(!cfqq->allocated[rw]);
2983 cfqq->allocated[rw]--;
2985 put_io_context(RQ_CIC(rq)->ioc);
2987 rq->elevator_private = NULL;
2988 rq->elevator_private2 = NULL;
2990 cfq_put_queue(cfqq);
2994 static struct cfq_queue *
2995 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
2996 struct cfq_queue *cfqq)
2998 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
2999 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3000 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3001 cfq_put_queue(cfqq);
3002 return cic_to_cfqq(cic, 1);
3005 static int should_split_cfqq(struct cfq_queue *cfqq)
3007 if (cfqq->seeky_start &&
3008 time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT))
3014 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3015 * was the last process referring to said cfqq.
3017 static struct cfq_queue *
3018 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3020 if (cfqq_process_refs(cfqq) == 1) {
3021 cfqq->seeky_start = 0;
3022 cfqq->pid = current->pid;
3023 cfq_clear_cfqq_coop(cfqq);
3027 cic_set_cfqq(cic, NULL, 1);
3028 cfq_put_queue(cfqq);
3032 * Allocate cfq data structures associated with this request.
3035 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3037 struct cfq_data *cfqd = q->elevator->elevator_data;
3038 struct cfq_io_context *cic;
3039 const int rw = rq_data_dir(rq);
3040 const bool is_sync = rq_is_sync(rq);
3041 struct cfq_queue *cfqq;
3042 unsigned long flags;
3044 might_sleep_if(gfp_mask & __GFP_WAIT);
3046 cic = cfq_get_io_context(cfqd, gfp_mask);
3048 spin_lock_irqsave(q->queue_lock, flags);
3054 cfqq = cic_to_cfqq(cic, is_sync);
3055 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3056 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3057 cic_set_cfqq(cic, cfqq, is_sync);
3060 * If the queue was seeky for too long, break it apart.
3062 if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) {
3063 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3064 cfqq = split_cfqq(cic, cfqq);
3070 * Check to see if this queue is scheduled to merge with
3071 * another, closely cooperating queue. The merging of
3072 * queues happens here as it must be done in process context.
3073 * The reference on new_cfqq was taken in merge_cfqqs.
3076 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3079 cfqq->allocated[rw]++;
3080 atomic_inc(&cfqq->ref);
3082 spin_unlock_irqrestore(q->queue_lock, flags);
3084 rq->elevator_private = cic;
3085 rq->elevator_private2 = cfqq;
3090 put_io_context(cic->ioc);
3092 cfq_schedule_dispatch(cfqd);
3093 spin_unlock_irqrestore(q->queue_lock, flags);
3094 cfq_log(cfqd, "set_request fail");
3098 static void cfq_kick_queue(struct work_struct *work)
3100 struct cfq_data *cfqd =
3101 container_of(work, struct cfq_data, unplug_work);
3102 struct request_queue *q = cfqd->queue;
3104 spin_lock_irq(q->queue_lock);
3105 __blk_run_queue(cfqd->queue);
3106 spin_unlock_irq(q->queue_lock);
3110 * Timer running if the active_queue is currently idling inside its time slice
3112 static void cfq_idle_slice_timer(unsigned long data)
3114 struct cfq_data *cfqd = (struct cfq_data *) data;
3115 struct cfq_queue *cfqq;
3116 unsigned long flags;
3119 cfq_log(cfqd, "idle timer fired");
3121 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3123 cfqq = cfqd->active_queue;
3128 * We saw a request before the queue expired, let it through
3130 if (cfq_cfqq_must_dispatch(cfqq))
3136 if (cfq_slice_used(cfqq))
3140 * only expire and reinvoke request handler, if there are
3141 * other queues with pending requests
3143 if (!cfqd->busy_queues)
3147 * not expired and it has a request pending, let it dispatch
3149 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3153 * Queue depth flag is reset only when the idle didn't succeed
3155 cfq_clear_cfqq_deep(cfqq);
3158 cfq_slice_expired(cfqd, timed_out);
3160 cfq_schedule_dispatch(cfqd);
3162 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3165 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3167 del_timer_sync(&cfqd->idle_slice_timer);
3168 cancel_work_sync(&cfqd->unplug_work);
3171 static void cfq_put_async_queues(struct cfq_data *cfqd)
3175 for (i = 0; i < IOPRIO_BE_NR; i++) {
3176 if (cfqd->async_cfqq[0][i])
3177 cfq_put_queue(cfqd->async_cfqq[0][i]);
3178 if (cfqd->async_cfqq[1][i])
3179 cfq_put_queue(cfqd->async_cfqq[1][i]);
3182 if (cfqd->async_idle_cfqq)
3183 cfq_put_queue(cfqd->async_idle_cfqq);
3186 static void cfq_exit_queue(struct elevator_queue *e)
3188 struct cfq_data *cfqd = e->elevator_data;
3189 struct request_queue *q = cfqd->queue;
3191 cfq_shutdown_timer_wq(cfqd);
3193 spin_lock_irq(q->queue_lock);
3195 if (cfqd->active_queue)
3196 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3198 while (!list_empty(&cfqd->cic_list)) {
3199 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3200 struct cfq_io_context,
3203 __cfq_exit_single_io_context(cfqd, cic);
3206 cfq_put_async_queues(cfqd);
3208 spin_unlock_irq(q->queue_lock);
3210 cfq_shutdown_timer_wq(cfqd);
3215 static void *cfq_init_queue(struct request_queue *q)
3217 struct cfq_data *cfqd;
3219 struct cfq_group *cfqg;
3220 struct cfq_rb_root *st;
3222 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3226 /* Init root service tree */
3227 cfqd->grp_service_tree = CFQ_RB_ROOT;
3229 /* Init root group */
3230 cfqg = &cfqd->root_group;
3231 for_each_cfqg_st(cfqg, i, j, st)
3233 RB_CLEAR_NODE(&cfqg->rb_node);
3235 /* Give preference to root group over other groups */
3236 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3239 * Not strictly needed (since RB_ROOT just clears the node and we
3240 * zeroed cfqd on alloc), but better be safe in case someone decides
3241 * to add magic to the rb code
3243 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3244 cfqd->prio_trees[i] = RB_ROOT;
3247 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3248 * Grab a permanent reference to it, so that the normal code flow
3249 * will not attempt to free it.
3251 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3252 atomic_inc(&cfqd->oom_cfqq.ref);
3253 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3255 INIT_LIST_HEAD(&cfqd->cic_list);
3259 init_timer(&cfqd->idle_slice_timer);
3260 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3261 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3263 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3265 cfqd->cfq_quantum = cfq_quantum;
3266 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3267 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3268 cfqd->cfq_back_max = cfq_back_max;
3269 cfqd->cfq_back_penalty = cfq_back_penalty;
3270 cfqd->cfq_slice[0] = cfq_slice_async;
3271 cfqd->cfq_slice[1] = cfq_slice_sync;
3272 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3273 cfqd->cfq_slice_idle = cfq_slice_idle;
3274 cfqd->cfq_latency = 1;
3276 cfqd->last_end_sync_rq = jiffies;
3280 static void cfq_slab_kill(void)
3283 * Caller already ensured that pending RCU callbacks are completed,
3284 * so we should have no busy allocations at this point.
3287 kmem_cache_destroy(cfq_pool);
3289 kmem_cache_destroy(cfq_ioc_pool);
3292 static int __init cfq_slab_setup(void)
3294 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3298 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3309 * sysfs parts below -->
3312 cfq_var_show(unsigned int var, char *page)
3314 return sprintf(page, "%d\n", var);
3318 cfq_var_store(unsigned int *var, const char *page, size_t count)
3320 char *p = (char *) page;
3322 *var = simple_strtoul(p, &p, 10);
3326 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3327 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3329 struct cfq_data *cfqd = e->elevator_data; \
3330 unsigned int __data = __VAR; \
3332 __data = jiffies_to_msecs(__data); \
3333 return cfq_var_show(__data, (page)); \
3335 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3336 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3337 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3338 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3339 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3340 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3341 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3342 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3343 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
3344 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
3345 #undef SHOW_FUNCTION
3347 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3348 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3350 struct cfq_data *cfqd = e->elevator_data; \
3351 unsigned int __data; \
3352 int ret = cfq_var_store(&__data, (page), count); \
3353 if (__data < (MIN)) \
3355 else if (__data > (MAX)) \
3358 *(__PTR) = msecs_to_jiffies(__data); \
3360 *(__PTR) = __data; \
3363 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
3364 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3366 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3368 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
3369 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3371 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
3372 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3373 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
3374 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3376 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
3377 #undef STORE_FUNCTION
3379 #define CFQ_ATTR(name) \
3380 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3382 static struct elv_fs_entry cfq_attrs[] = {
3384 CFQ_ATTR(fifo_expire_sync),
3385 CFQ_ATTR(fifo_expire_async),
3386 CFQ_ATTR(back_seek_max),
3387 CFQ_ATTR(back_seek_penalty),
3388 CFQ_ATTR(slice_sync),
3389 CFQ_ATTR(slice_async),
3390 CFQ_ATTR(slice_async_rq),
3391 CFQ_ATTR(slice_idle),
3392 CFQ_ATTR(low_latency),
3396 static struct elevator_type iosched_cfq = {
3398 .elevator_merge_fn = cfq_merge,
3399 .elevator_merged_fn = cfq_merged_request,
3400 .elevator_merge_req_fn = cfq_merged_requests,
3401 .elevator_allow_merge_fn = cfq_allow_merge,
3402 .elevator_dispatch_fn = cfq_dispatch_requests,
3403 .elevator_add_req_fn = cfq_insert_request,
3404 .elevator_activate_req_fn = cfq_activate_request,
3405 .elevator_deactivate_req_fn = cfq_deactivate_request,
3406 .elevator_queue_empty_fn = cfq_queue_empty,
3407 .elevator_completed_req_fn = cfq_completed_request,
3408 .elevator_former_req_fn = elv_rb_former_request,
3409 .elevator_latter_req_fn = elv_rb_latter_request,
3410 .elevator_set_req_fn = cfq_set_request,
3411 .elevator_put_req_fn = cfq_put_request,
3412 .elevator_may_queue_fn = cfq_may_queue,
3413 .elevator_init_fn = cfq_init_queue,
3414 .elevator_exit_fn = cfq_exit_queue,
3415 .trim = cfq_free_io_context,
3417 .elevator_attrs = cfq_attrs,
3418 .elevator_name = "cfq",
3419 .elevator_owner = THIS_MODULE,
3422 static int __init cfq_init(void)
3425 * could be 0 on HZ < 1000 setups
3427 if (!cfq_slice_async)
3428 cfq_slice_async = 1;
3429 if (!cfq_slice_idle)
3432 if (cfq_slab_setup())
3435 elv_register(&iosched_cfq);
3440 static void __exit cfq_exit(void)
3442 DECLARE_COMPLETION_ONSTACK(all_gone);
3443 elv_unregister(&iosched_cfq);
3444 ioc_gone = &all_gone;
3445 /* ioc_gone's update must be visible before reading ioc_count */
3449 * this also protects us from entering cfq_slab_kill() with
3450 * pending RCU callbacks
3452 if (elv_ioc_count_read(cfq_ioc_count))
3453 wait_for_completion(&all_gone);
3457 module_init(cfq_init);
3458 module_exit(cfq_exit);
3460 MODULE_AUTHOR("Jens Axboe");
3461 MODULE_LICENSE("GPL");
3462 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");