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/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
22 /* max queue in one round of service */
23 static const int cfq_quantum = 8;
24 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max = 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty = 2;
29 static const int cfq_slice_sync = HZ / 10;
30 static int cfq_slice_async = HZ / 25;
31 static const int cfq_slice_async_rq = 2;
32 static int cfq_slice_idle = HZ / 125;
33 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
34 static const int cfq_hist_divisor = 4;
37 * offset from end of service tree
39 #define CFQ_IDLE_DELAY (HZ / 5)
42 * below this threshold, we consider thinktime immediate
44 #define CFQ_MIN_TT (2)
46 #define CFQ_SLICE_SCALE (5)
47 #define CFQ_HW_QUEUE_MIN (5)
48 #define CFQ_SERVICE_SHIFT 12
50 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
51 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
52 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
53 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
56 ((struct cfq_io_context *) (rq)->elevator_private)
57 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
58 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
60 static struct kmem_cache *cfq_pool;
61 static struct kmem_cache *cfq_ioc_pool;
63 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
64 static struct completion *ioc_gone;
65 static DEFINE_SPINLOCK(ioc_gone_lock);
67 static DEFINE_SPINLOCK(cic_index_lock);
68 static DEFINE_IDA(cic_index_ida);
70 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
71 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
72 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
74 #define sample_valid(samples) ((samples) > 80)
75 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
78 * Most of our rbtree usage is for sorting with min extraction, so
79 * if we cache the leftmost node we don't have to walk down the tree
80 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
81 * move this into the elevator for the rq sorting as well.
87 unsigned total_weight;
89 struct rb_node *active;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data *cfqd;
104 /* service_tree member */
105 struct rb_node rb_node;
106 /* service_tree key */
107 unsigned long rb_key;
108 /* prio tree member */
109 struct rb_node p_node;
110 /* prio tree root we belong to, if any */
111 struct rb_root *p_root;
112 /* sorted list of pending requests */
113 struct rb_root sort_list;
114 /* if fifo isn't expired, next request to serve */
115 struct request *next_rq;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start;
125 unsigned int allocated_slice;
126 unsigned int slice_dispatch;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start;
129 unsigned long slice_end;
132 /* pending metadata requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio, org_ioprio;
139 unsigned short ioprio_class, org_ioprio_class;
144 sector_t last_request_pos;
146 struct cfq_rb_root *service_tree;
147 struct cfq_queue *new_cfqq;
148 struct cfq_group *cfqg;
149 struct cfq_group *orig_cfqg;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
164 * Second index in the service_trees.
168 SYNC_NOIDLE_WORKLOAD = 1,
172 /* This is per cgroup per device grouping structure */
174 /* group service_tree member */
175 struct rb_node rb_node;
177 /* group service_tree key */
182 /* number of cfqq currently on this group */
186 * Per group busy queus average. Useful for workload slice calc. We
187 * create the array for each prio class but at run time it is used
188 * only for RT and BE class and slot for IDLE class remains unused.
189 * This is primarily done to avoid confusion and a gcc warning.
191 unsigned int busy_queues_avg[CFQ_PRIO_NR];
193 * rr lists of queues with requests. We maintain service trees for
194 * RT and BE classes. These trees are subdivided in subclasses
195 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
196 * class there is no subclassification and all the cfq queues go on
197 * a single tree service_tree_idle.
198 * Counts are embedded in the cfq_rb_root
200 struct cfq_rb_root service_trees[2][3];
201 struct cfq_rb_root service_tree_idle;
203 unsigned long saved_workload_slice;
204 enum wl_type_t saved_workload;
205 enum wl_prio_t saved_serving_prio;
206 struct blkio_group blkg;
207 #ifdef CONFIG_CFQ_GROUP_IOSCHED
208 struct hlist_node cfqd_node;
214 * Per block device queue structure
217 struct request_queue *queue;
218 /* Root service tree for cfq_groups */
219 struct cfq_rb_root grp_service_tree;
220 struct cfq_group root_group;
223 * The priority currently being served
225 enum wl_prio_t serving_prio;
226 enum wl_type_t serving_type;
227 unsigned long workload_expires;
228 struct cfq_group *serving_group;
231 * Each priority tree is sorted by next_request position. These
232 * trees are used when determining if two or more queues are
233 * interleaving requests (see cfq_close_cooperator).
235 struct rb_root prio_trees[CFQ_PRIO_LISTS];
237 unsigned int busy_queues;
243 * queue-depth detection
249 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
250 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
253 int hw_tag_est_depth;
254 unsigned int hw_tag_samples;
257 * idle window management
259 struct timer_list idle_slice_timer;
260 struct work_struct unplug_work;
262 struct cfq_queue *active_queue;
263 struct cfq_io_context *active_cic;
266 * async queue for each priority case
268 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
269 struct cfq_queue *async_idle_cfqq;
271 sector_t last_position;
274 * tunables, see top of file
276 unsigned int cfq_quantum;
277 unsigned int cfq_fifo_expire[2];
278 unsigned int cfq_back_penalty;
279 unsigned int cfq_back_max;
280 unsigned int cfq_slice[2];
281 unsigned int cfq_slice_async_rq;
282 unsigned int cfq_slice_idle;
283 unsigned int cfq_latency;
284 unsigned int cfq_group_isolation;
286 unsigned int cic_index;
287 struct list_head cic_list;
290 * Fallback dummy cfqq for extreme OOM conditions
292 struct cfq_queue oom_cfqq;
294 unsigned long last_delayed_sync;
296 /* List of cfq groups being managed on this device*/
297 struct hlist_head cfqg_list;
301 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
303 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
310 if (prio == IDLE_WORKLOAD)
311 return &cfqg->service_tree_idle;
313 return &cfqg->service_trees[prio][type];
316 enum cfqq_state_flags {
317 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
318 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
319 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
320 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
321 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
322 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
323 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
324 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
325 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
326 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
327 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
328 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
329 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
332 #define CFQ_CFQQ_FNS(name) \
333 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
335 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
337 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
339 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
341 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
343 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
347 CFQ_CFQQ_FNS(wait_request);
348 CFQ_CFQQ_FNS(must_dispatch);
349 CFQ_CFQQ_FNS(must_alloc_slice);
350 CFQ_CFQQ_FNS(fifo_expire);
351 CFQ_CFQQ_FNS(idle_window);
352 CFQ_CFQQ_FNS(prio_changed);
353 CFQ_CFQQ_FNS(slice_new);
356 CFQ_CFQQ_FNS(split_coop);
358 CFQ_CFQQ_FNS(wait_busy);
361 #ifdef CONFIG_CFQ_GROUP_IOSCHED
362 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
363 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
364 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
365 blkg_path(&(cfqq)->cfqg->blkg), ##args);
367 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
368 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
369 blkg_path(&(cfqg)->blkg), ##args); \
372 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
373 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
374 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
376 #define cfq_log(cfqd, fmt, args...) \
377 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
379 /* Traverses through cfq group service trees */
380 #define for_each_cfqg_st(cfqg, i, j, st) \
381 for (i = 0; i <= IDLE_WORKLOAD; i++) \
382 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
383 : &cfqg->service_tree_idle; \
384 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
385 (i == IDLE_WORKLOAD && j == 0); \
386 j++, st = i < IDLE_WORKLOAD ? \
387 &cfqg->service_trees[i][j]: NULL) \
390 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
392 if (cfq_class_idle(cfqq))
393 return IDLE_WORKLOAD;
394 if (cfq_class_rt(cfqq))
400 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
402 if (!cfq_cfqq_sync(cfqq))
403 return ASYNC_WORKLOAD;
404 if (!cfq_cfqq_idle_window(cfqq))
405 return SYNC_NOIDLE_WORKLOAD;
406 return SYNC_WORKLOAD;
409 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
410 struct cfq_data *cfqd,
411 struct cfq_group *cfqg)
413 if (wl == IDLE_WORKLOAD)
414 return cfqg->service_tree_idle.count;
416 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
417 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
418 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
421 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
422 struct cfq_group *cfqg)
424 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
425 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
428 static void cfq_dispatch_insert(struct request_queue *, struct request *);
429 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
430 struct io_context *, gfp_t);
431 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
432 struct io_context *);
434 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
437 return cic->cfqq[is_sync];
440 static inline void cic_set_cfqq(struct cfq_io_context *cic,
441 struct cfq_queue *cfqq, bool is_sync)
443 cic->cfqq[is_sync] = cfqq;
446 #define CIC_DEAD_KEY 1ul
447 #define CIC_DEAD_INDEX_SHIFT 1
449 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
451 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
454 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
456 struct cfq_data *cfqd = cic->key;
458 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
465 * We regard a request as SYNC, if it's either a read or has the SYNC bit
466 * set (in which case it could also be direct WRITE).
468 static inline bool cfq_bio_sync(struct bio *bio)
470 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
474 * scheduler run of queue, if there are requests pending and no one in the
475 * driver that will restart queueing
477 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
479 if (cfqd->busy_queues) {
480 cfq_log(cfqd, "schedule dispatch");
481 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
485 static int cfq_queue_empty(struct request_queue *q)
487 struct cfq_data *cfqd = q->elevator->elevator_data;
489 return !cfqd->rq_queued;
493 * Scale schedule slice based on io priority. Use the sync time slice only
494 * if a queue is marked sync and has sync io queued. A sync queue with async
495 * io only, should not get full sync slice length.
497 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
500 const int base_slice = cfqd->cfq_slice[sync];
502 WARN_ON(prio >= IOPRIO_BE_NR);
504 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
508 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
510 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
513 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
515 u64 d = delta << CFQ_SERVICE_SHIFT;
517 d = d * BLKIO_WEIGHT_DEFAULT;
518 do_div(d, cfqg->weight);
522 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
524 s64 delta = (s64)(vdisktime - min_vdisktime);
526 min_vdisktime = vdisktime;
528 return min_vdisktime;
531 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
533 s64 delta = (s64)(vdisktime - min_vdisktime);
535 min_vdisktime = vdisktime;
537 return min_vdisktime;
540 static void update_min_vdisktime(struct cfq_rb_root *st)
542 u64 vdisktime = st->min_vdisktime;
543 struct cfq_group *cfqg;
546 cfqg = rb_entry_cfqg(st->active);
547 vdisktime = cfqg->vdisktime;
551 cfqg = rb_entry_cfqg(st->left);
552 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
555 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
559 * get averaged number of queues of RT/BE priority.
560 * average is updated, with a formula that gives more weight to higher numbers,
561 * to quickly follows sudden increases and decrease slowly
564 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
565 struct cfq_group *cfqg, bool rt)
567 unsigned min_q, max_q;
568 unsigned mult = cfq_hist_divisor - 1;
569 unsigned round = cfq_hist_divisor / 2;
570 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
572 min_q = min(cfqg->busy_queues_avg[rt], busy);
573 max_q = max(cfqg->busy_queues_avg[rt], busy);
574 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
576 return cfqg->busy_queues_avg[rt];
579 static inline unsigned
580 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
582 struct cfq_rb_root *st = &cfqd->grp_service_tree;
584 return cfq_target_latency * cfqg->weight / st->total_weight;
588 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
590 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
591 if (cfqd->cfq_latency) {
593 * interested queues (we consider only the ones with the same
594 * priority class in the cfq group)
596 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
598 unsigned sync_slice = cfqd->cfq_slice[1];
599 unsigned expect_latency = sync_slice * iq;
600 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
602 if (expect_latency > group_slice) {
603 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
604 /* scale low_slice according to IO priority
605 * and sync vs async */
607 min(slice, base_low_slice * slice / sync_slice);
608 /* the adapted slice value is scaled to fit all iqs
609 * into the target latency */
610 slice = max(slice * group_slice / expect_latency,
614 cfqq->slice_start = jiffies;
615 cfqq->slice_end = jiffies + slice;
616 cfqq->allocated_slice = slice;
617 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
621 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
622 * isn't valid until the first request from the dispatch is activated
623 * and the slice time set.
625 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
627 if (cfq_cfqq_slice_new(cfqq))
629 if (time_before(jiffies, cfqq->slice_end))
636 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
637 * We choose the request that is closest to the head right now. Distance
638 * behind the head is penalized and only allowed to a certain extent.
640 static struct request *
641 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
643 sector_t s1, s2, d1 = 0, d2 = 0;
644 unsigned long back_max;
645 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
646 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
647 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
649 if (rq1 == NULL || rq1 == rq2)
654 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
656 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
658 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
660 else if ((rq2->cmd_flags & REQ_META) &&
661 !(rq1->cmd_flags & REQ_META))
664 s1 = blk_rq_pos(rq1);
665 s2 = blk_rq_pos(rq2);
668 * by definition, 1KiB is 2 sectors
670 back_max = cfqd->cfq_back_max * 2;
673 * Strict one way elevator _except_ in the case where we allow
674 * short backward seeks which are biased as twice the cost of a
675 * similar forward seek.
679 else if (s1 + back_max >= last)
680 d1 = (last - s1) * cfqd->cfq_back_penalty;
682 wrap |= CFQ_RQ1_WRAP;
686 else if (s2 + back_max >= last)
687 d2 = (last - s2) * cfqd->cfq_back_penalty;
689 wrap |= CFQ_RQ2_WRAP;
691 /* Found required data */
694 * By doing switch() on the bit mask "wrap" we avoid having to
695 * check two variables for all permutations: --> faster!
698 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
714 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
717 * Since both rqs are wrapped,
718 * start with the one that's further behind head
719 * (--> only *one* back seek required),
720 * since back seek takes more time than forward.
730 * The below is leftmost cache rbtree addon
732 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
734 /* Service tree is empty */
739 root->left = rb_first(&root->rb);
742 return rb_entry(root->left, struct cfq_queue, rb_node);
747 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
750 root->left = rb_first(&root->rb);
753 return rb_entry_cfqg(root->left);
758 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
764 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
768 rb_erase_init(n, &root->rb);
773 * would be nice to take fifo expire time into account as well
775 static struct request *
776 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
777 struct request *last)
779 struct rb_node *rbnext = rb_next(&last->rb_node);
780 struct rb_node *rbprev = rb_prev(&last->rb_node);
781 struct request *next = NULL, *prev = NULL;
783 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
786 prev = rb_entry_rq(rbprev);
789 next = rb_entry_rq(rbnext);
791 rbnext = rb_first(&cfqq->sort_list);
792 if (rbnext && rbnext != &last->rb_node)
793 next = rb_entry_rq(rbnext);
796 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
799 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
800 struct cfq_queue *cfqq)
803 * just an approximation, should be ok.
805 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
806 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
810 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
812 return cfqg->vdisktime - st->min_vdisktime;
816 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
818 struct rb_node **node = &st->rb.rb_node;
819 struct rb_node *parent = NULL;
820 struct cfq_group *__cfqg;
821 s64 key = cfqg_key(st, cfqg);
824 while (*node != NULL) {
826 __cfqg = rb_entry_cfqg(parent);
828 if (key < cfqg_key(st, __cfqg))
829 node = &parent->rb_left;
831 node = &parent->rb_right;
837 st->left = &cfqg->rb_node;
839 rb_link_node(&cfqg->rb_node, parent, node);
840 rb_insert_color(&cfqg->rb_node, &st->rb);
844 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
846 struct cfq_rb_root *st = &cfqd->grp_service_tree;
847 struct cfq_group *__cfqg;
855 * Currently put the group at the end. Later implement something
856 * so that groups get lesser vtime based on their weights, so that
857 * if group does not loose all if it was not continously backlogged.
859 n = rb_last(&st->rb);
861 __cfqg = rb_entry_cfqg(n);
862 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
864 cfqg->vdisktime = st->min_vdisktime;
866 __cfq_group_service_tree_add(st, cfqg);
868 st->total_weight += cfqg->weight;
872 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
874 struct cfq_rb_root *st = &cfqd->grp_service_tree;
876 if (st->active == &cfqg->rb_node)
879 BUG_ON(cfqg->nr_cfqq < 1);
882 /* If there are other cfq queues under this group, don't delete it */
886 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
888 st->total_weight -= cfqg->weight;
889 if (!RB_EMPTY_NODE(&cfqg->rb_node))
890 cfq_rb_erase(&cfqg->rb_node, st);
891 cfqg->saved_workload_slice = 0;
892 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
895 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
897 unsigned int slice_used;
900 * Queue got expired before even a single request completed or
901 * got expired immediately after first request completion.
903 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
905 * Also charge the seek time incurred to the group, otherwise
906 * if there are mutiple queues in the group, each can dispatch
907 * a single request on seeky media and cause lots of seek time
908 * and group will never know it.
910 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
913 slice_used = jiffies - cfqq->slice_start;
914 if (slice_used > cfqq->allocated_slice)
915 slice_used = cfqq->allocated_slice;
918 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
922 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
923 struct cfq_queue *cfqq)
925 struct cfq_rb_root *st = &cfqd->grp_service_tree;
926 unsigned int used_sl, charge_sl;
927 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
928 - cfqg->service_tree_idle.count;
931 used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
933 if (!cfq_cfqq_sync(cfqq) && !nr_sync)
934 charge_sl = cfqq->allocated_slice;
936 /* Can't update vdisktime while group is on service tree */
937 cfq_rb_erase(&cfqg->rb_node, st);
938 cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
939 __cfq_group_service_tree_add(st, cfqg);
941 /* This group is being expired. Save the context */
942 if (time_after(cfqd->workload_expires, jiffies)) {
943 cfqg->saved_workload_slice = cfqd->workload_expires
945 cfqg->saved_workload = cfqd->serving_type;
946 cfqg->saved_serving_prio = cfqd->serving_prio;
948 cfqg->saved_workload_slice = 0;
950 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
952 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
953 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
956 #ifdef CONFIG_CFQ_GROUP_IOSCHED
957 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
960 return container_of(blkg, struct cfq_group, blkg);
964 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
967 cfqg_of_blkg(blkg)->weight = weight;
970 static struct cfq_group *
971 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
973 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
974 struct cfq_group *cfqg = NULL;
977 struct cfq_rb_root *st;
978 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
979 unsigned int major, minor;
981 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
982 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
983 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
984 cfqg->blkg.dev = MKDEV(major, minor);
990 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
994 for_each_cfqg_st(cfqg, i, j, st)
996 RB_CLEAR_NODE(&cfqg->rb_node);
999 * Take the initial reference that will be released on destroy
1000 * This can be thought of a joint reference by cgroup and
1001 * elevator which will be dropped by either elevator exit
1002 * or cgroup deletion path depending on who is exiting first.
1004 atomic_set(&cfqg->ref, 1);
1006 /* Add group onto cgroup list */
1007 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1008 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1009 MKDEV(major, minor));
1010 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1012 /* Add group on cfqd list */
1013 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1020 * Search for the cfq group current task belongs to. If create = 1, then also
1021 * create the cfq group if it does not exist. request_queue lock must be held.
1023 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1025 struct cgroup *cgroup;
1026 struct cfq_group *cfqg = NULL;
1029 cgroup = task_cgroup(current, blkio_subsys_id);
1030 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1031 if (!cfqg && create)
1032 cfqg = &cfqd->root_group;
1037 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1039 atomic_inc(&cfqg->ref);
1043 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1045 /* Currently, all async queues are mapped to root group */
1046 if (!cfq_cfqq_sync(cfqq))
1047 cfqg = &cfqq->cfqd->root_group;
1050 /* cfqq reference on cfqg */
1051 atomic_inc(&cfqq->cfqg->ref);
1054 static void cfq_put_cfqg(struct cfq_group *cfqg)
1056 struct cfq_rb_root *st;
1059 BUG_ON(atomic_read(&cfqg->ref) <= 0);
1060 if (!atomic_dec_and_test(&cfqg->ref))
1062 for_each_cfqg_st(cfqg, i, j, st)
1063 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
1067 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1069 /* Something wrong if we are trying to remove same group twice */
1070 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1072 hlist_del_init(&cfqg->cfqd_node);
1075 * Put the reference taken at the time of creation so that when all
1076 * queues are gone, group can be destroyed.
1081 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1083 struct hlist_node *pos, *n;
1084 struct cfq_group *cfqg;
1086 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1088 * If cgroup removal path got to blk_group first and removed
1089 * it from cgroup list, then it will take care of destroying
1092 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1093 cfq_destroy_cfqg(cfqd, cfqg);
1098 * Blk cgroup controller notification saying that blkio_group object is being
1099 * delinked as associated cgroup object is going away. That also means that
1100 * no new IO will come in this group. So get rid of this group as soon as
1101 * any pending IO in the group is finished.
1103 * This function is called under rcu_read_lock(). key is the rcu protected
1104 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1107 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1108 * it should not be NULL as even if elevator was exiting, cgroup deltion
1109 * path got to it first.
1111 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1113 unsigned long flags;
1114 struct cfq_data *cfqd = key;
1116 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1117 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1118 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1121 #else /* GROUP_IOSCHED */
1122 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1124 return &cfqd->root_group;
1127 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1133 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1137 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1138 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1140 #endif /* GROUP_IOSCHED */
1143 * The cfqd->service_trees holds all pending cfq_queue's that have
1144 * requests waiting to be processed. It is sorted in the order that
1145 * we will service the queues.
1147 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1150 struct rb_node **p, *parent;
1151 struct cfq_queue *__cfqq;
1152 unsigned long rb_key;
1153 struct cfq_rb_root *service_tree;
1156 int group_changed = 0;
1158 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1159 if (!cfqd->cfq_group_isolation
1160 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1161 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1162 /* Move this cfq to root group */
1163 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1164 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1165 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1166 cfqq->orig_cfqg = cfqq->cfqg;
1167 cfqq->cfqg = &cfqd->root_group;
1168 atomic_inc(&cfqd->root_group.ref);
1170 } else if (!cfqd->cfq_group_isolation
1171 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1172 /* cfqq is sequential now needs to go to its original group */
1173 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1174 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1175 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1176 cfq_put_cfqg(cfqq->cfqg);
1177 cfqq->cfqg = cfqq->orig_cfqg;
1178 cfqq->orig_cfqg = NULL;
1180 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1184 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1186 if (cfq_class_idle(cfqq)) {
1187 rb_key = CFQ_IDLE_DELAY;
1188 parent = rb_last(&service_tree->rb);
1189 if (parent && parent != &cfqq->rb_node) {
1190 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1191 rb_key += __cfqq->rb_key;
1194 } else if (!add_front) {
1196 * Get our rb key offset. Subtract any residual slice
1197 * value carried from last service. A negative resid
1198 * count indicates slice overrun, and this should position
1199 * the next service time further away in the tree.
1201 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1202 rb_key -= cfqq->slice_resid;
1203 cfqq->slice_resid = 0;
1206 __cfqq = cfq_rb_first(service_tree);
1207 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1210 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1213 * same position, nothing more to do
1215 if (rb_key == cfqq->rb_key &&
1216 cfqq->service_tree == service_tree)
1219 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1220 cfqq->service_tree = NULL;
1225 cfqq->service_tree = service_tree;
1226 p = &service_tree->rb.rb_node;
1231 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1234 * sort by key, that represents service time.
1236 if (time_before(rb_key, __cfqq->rb_key))
1239 n = &(*p)->rb_right;
1247 service_tree->left = &cfqq->rb_node;
1249 cfqq->rb_key = rb_key;
1250 rb_link_node(&cfqq->rb_node, parent, p);
1251 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1252 service_tree->count++;
1253 if ((add_front || !new_cfqq) && !group_changed)
1255 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1258 static struct cfq_queue *
1259 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1260 sector_t sector, struct rb_node **ret_parent,
1261 struct rb_node ***rb_link)
1263 struct rb_node **p, *parent;
1264 struct cfq_queue *cfqq = NULL;
1272 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1275 * Sort strictly based on sector. Smallest to the left,
1276 * largest to the right.
1278 if (sector > blk_rq_pos(cfqq->next_rq))
1279 n = &(*p)->rb_right;
1280 else if (sector < blk_rq_pos(cfqq->next_rq))
1288 *ret_parent = parent;
1294 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1296 struct rb_node **p, *parent;
1297 struct cfq_queue *__cfqq;
1300 rb_erase(&cfqq->p_node, cfqq->p_root);
1301 cfqq->p_root = NULL;
1304 if (cfq_class_idle(cfqq))
1309 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1310 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1311 blk_rq_pos(cfqq->next_rq), &parent, &p);
1313 rb_link_node(&cfqq->p_node, parent, p);
1314 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1316 cfqq->p_root = NULL;
1320 * Update cfqq's position in the service tree.
1322 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1325 * Resorting requires the cfqq to be on the RR list already.
1327 if (cfq_cfqq_on_rr(cfqq)) {
1328 cfq_service_tree_add(cfqd, cfqq, 0);
1329 cfq_prio_tree_add(cfqd, cfqq);
1334 * add to busy list of queues for service, trying to be fair in ordering
1335 * the pending list according to last request service
1337 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1339 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1340 BUG_ON(cfq_cfqq_on_rr(cfqq));
1341 cfq_mark_cfqq_on_rr(cfqq);
1342 cfqd->busy_queues++;
1344 cfq_resort_rr_list(cfqd, cfqq);
1348 * Called when the cfqq no longer has requests pending, remove it from
1351 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1353 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1354 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1355 cfq_clear_cfqq_on_rr(cfqq);
1357 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1358 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1359 cfqq->service_tree = NULL;
1362 rb_erase(&cfqq->p_node, cfqq->p_root);
1363 cfqq->p_root = NULL;
1366 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1367 BUG_ON(!cfqd->busy_queues);
1368 cfqd->busy_queues--;
1372 * rb tree support functions
1374 static void cfq_del_rq_rb(struct request *rq)
1376 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1377 const int sync = rq_is_sync(rq);
1379 BUG_ON(!cfqq->queued[sync]);
1380 cfqq->queued[sync]--;
1382 elv_rb_del(&cfqq->sort_list, rq);
1384 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1386 * Queue will be deleted from service tree when we actually
1387 * expire it later. Right now just remove it from prio tree
1391 rb_erase(&cfqq->p_node, cfqq->p_root);
1392 cfqq->p_root = NULL;
1397 static void cfq_add_rq_rb(struct request *rq)
1399 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1400 struct cfq_data *cfqd = cfqq->cfqd;
1401 struct request *__alias, *prev;
1403 cfqq->queued[rq_is_sync(rq)]++;
1406 * looks a little odd, but the first insert might return an alias.
1407 * if that happens, put the alias on the dispatch list
1409 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1410 cfq_dispatch_insert(cfqd->queue, __alias);
1412 if (!cfq_cfqq_on_rr(cfqq))
1413 cfq_add_cfqq_rr(cfqd, cfqq);
1416 * check if this request is a better next-serve candidate
1418 prev = cfqq->next_rq;
1419 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1422 * adjust priority tree position, if ->next_rq changes
1424 if (prev != cfqq->next_rq)
1425 cfq_prio_tree_add(cfqd, cfqq);
1427 BUG_ON(!cfqq->next_rq);
1430 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1432 elv_rb_del(&cfqq->sort_list, rq);
1433 cfqq->queued[rq_is_sync(rq)]--;
1434 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1435 rq_data_dir(rq), rq_is_sync(rq));
1437 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1438 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1442 static struct request *
1443 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1445 struct task_struct *tsk = current;
1446 struct cfq_io_context *cic;
1447 struct cfq_queue *cfqq;
1449 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1453 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1455 sector_t sector = bio->bi_sector + bio_sectors(bio);
1457 return elv_rb_find(&cfqq->sort_list, sector);
1463 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1465 struct cfq_data *cfqd = q->elevator->elevator_data;
1467 cfqd->rq_in_driver++;
1468 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1469 cfqd->rq_in_driver);
1471 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1474 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1476 struct cfq_data *cfqd = q->elevator->elevator_data;
1478 WARN_ON(!cfqd->rq_in_driver);
1479 cfqd->rq_in_driver--;
1480 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1481 cfqd->rq_in_driver);
1484 static void cfq_remove_request(struct request *rq)
1486 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1488 if (cfqq->next_rq == rq)
1489 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1491 list_del_init(&rq->queuelist);
1494 cfqq->cfqd->rq_queued--;
1495 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1496 rq_data_dir(rq), rq_is_sync(rq));
1497 if (rq->cmd_flags & REQ_META) {
1498 WARN_ON(!cfqq->meta_pending);
1499 cfqq->meta_pending--;
1503 static int cfq_merge(struct request_queue *q, struct request **req,
1506 struct cfq_data *cfqd = q->elevator->elevator_data;
1507 struct request *__rq;
1509 __rq = cfq_find_rq_fmerge(cfqd, bio);
1510 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1512 return ELEVATOR_FRONT_MERGE;
1515 return ELEVATOR_NO_MERGE;
1518 static void cfq_merged_request(struct request_queue *q, struct request *req,
1521 if (type == ELEVATOR_FRONT_MERGE) {
1522 struct cfq_queue *cfqq = RQ_CFQQ(req);
1524 cfq_reposition_rq_rb(cfqq, req);
1528 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1531 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1532 bio_data_dir(bio), cfq_bio_sync(bio));
1536 cfq_merged_requests(struct request_queue *q, struct request *rq,
1537 struct request *next)
1539 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1541 * reposition in fifo if next is older than rq
1543 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1544 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1545 list_move(&rq->queuelist, &next->queuelist);
1546 rq_set_fifo_time(rq, rq_fifo_time(next));
1549 if (cfqq->next_rq == next)
1551 cfq_remove_request(next);
1552 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1553 rq_data_dir(next), rq_is_sync(next));
1556 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1559 struct cfq_data *cfqd = q->elevator->elevator_data;
1560 struct cfq_io_context *cic;
1561 struct cfq_queue *cfqq;
1564 * Disallow merge of a sync bio into an async request.
1566 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1570 * Lookup the cfqq that this bio will be queued with. Allow
1571 * merge only if rq is queued there.
1573 cic = cfq_cic_lookup(cfqd, current->io_context);
1577 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1578 return cfqq == RQ_CFQQ(rq);
1581 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1583 del_timer(&cfqd->idle_slice_timer);
1584 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1587 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1588 struct cfq_queue *cfqq)
1591 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1592 cfqd->serving_prio, cfqd->serving_type);
1593 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1594 cfqq->slice_start = 0;
1595 cfqq->dispatch_start = jiffies;
1596 cfqq->allocated_slice = 0;
1597 cfqq->slice_end = 0;
1598 cfqq->slice_dispatch = 0;
1600 cfq_clear_cfqq_wait_request(cfqq);
1601 cfq_clear_cfqq_must_dispatch(cfqq);
1602 cfq_clear_cfqq_must_alloc_slice(cfqq);
1603 cfq_clear_cfqq_fifo_expire(cfqq);
1604 cfq_mark_cfqq_slice_new(cfqq);
1606 cfq_del_timer(cfqd, cfqq);
1609 cfqd->active_queue = cfqq;
1613 * current cfqq expired its slice (or was too idle), select new one
1616 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1619 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1621 if (cfq_cfqq_wait_request(cfqq))
1622 cfq_del_timer(cfqd, cfqq);
1624 cfq_clear_cfqq_wait_request(cfqq);
1625 cfq_clear_cfqq_wait_busy(cfqq);
1628 * If this cfqq is shared between multiple processes, check to
1629 * make sure that those processes are still issuing I/Os within
1630 * the mean seek distance. If not, it may be time to break the
1631 * queues apart again.
1633 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1634 cfq_mark_cfqq_split_coop(cfqq);
1637 * store what was left of this slice, if the queue idled/timed out
1639 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
1640 cfqq->slice_resid = cfqq->slice_end - jiffies;
1641 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1644 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1646 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1647 cfq_del_cfqq_rr(cfqd, cfqq);
1649 cfq_resort_rr_list(cfqd, cfqq);
1651 if (cfqq == cfqd->active_queue)
1652 cfqd->active_queue = NULL;
1654 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
1655 cfqd->grp_service_tree.active = NULL;
1657 if (cfqd->active_cic) {
1658 put_io_context(cfqd->active_cic->ioc);
1659 cfqd->active_cic = NULL;
1663 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1665 struct cfq_queue *cfqq = cfqd->active_queue;
1668 __cfq_slice_expired(cfqd, cfqq, timed_out);
1672 * Get next queue for service. Unless we have a queue preemption,
1673 * we'll simply select the first cfqq in the service tree.
1675 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1677 struct cfq_rb_root *service_tree =
1678 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1679 cfqd->serving_type);
1681 if (!cfqd->rq_queued)
1684 /* There is nothing to dispatch */
1687 if (RB_EMPTY_ROOT(&service_tree->rb))
1689 return cfq_rb_first(service_tree);
1692 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1694 struct cfq_group *cfqg;
1695 struct cfq_queue *cfqq;
1697 struct cfq_rb_root *st;
1699 if (!cfqd->rq_queued)
1702 cfqg = cfq_get_next_cfqg(cfqd);
1706 for_each_cfqg_st(cfqg, i, j, st)
1707 if ((cfqq = cfq_rb_first(st)) != NULL)
1713 * Get and set a new active queue for service.
1715 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1716 struct cfq_queue *cfqq)
1719 cfqq = cfq_get_next_queue(cfqd);
1721 __cfq_set_active_queue(cfqd, cfqq);
1725 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1728 if (blk_rq_pos(rq) >= cfqd->last_position)
1729 return blk_rq_pos(rq) - cfqd->last_position;
1731 return cfqd->last_position - blk_rq_pos(rq);
1734 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1737 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1740 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1741 struct cfq_queue *cur_cfqq)
1743 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1744 struct rb_node *parent, *node;
1745 struct cfq_queue *__cfqq;
1746 sector_t sector = cfqd->last_position;
1748 if (RB_EMPTY_ROOT(root))
1752 * First, if we find a request starting at the end of the last
1753 * request, choose it.
1755 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1760 * If the exact sector wasn't found, the parent of the NULL leaf
1761 * will contain the closest sector.
1763 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1764 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1767 if (blk_rq_pos(__cfqq->next_rq) < sector)
1768 node = rb_next(&__cfqq->p_node);
1770 node = rb_prev(&__cfqq->p_node);
1774 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1775 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1783 * cur_cfqq - passed in so that we don't decide that the current queue is
1784 * closely cooperating with itself.
1786 * So, basically we're assuming that that cur_cfqq has dispatched at least
1787 * one request, and that cfqd->last_position reflects a position on the disk
1788 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1791 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1792 struct cfq_queue *cur_cfqq)
1794 struct cfq_queue *cfqq;
1796 if (cfq_class_idle(cur_cfqq))
1798 if (!cfq_cfqq_sync(cur_cfqq))
1800 if (CFQQ_SEEKY(cur_cfqq))
1804 * Don't search priority tree if it's the only queue in the group.
1806 if (cur_cfqq->cfqg->nr_cfqq == 1)
1810 * We should notice if some of the queues are cooperating, eg
1811 * working closely on the same area of the disk. In that case,
1812 * we can group them together and don't waste time idling.
1814 cfqq = cfqq_close(cfqd, cur_cfqq);
1818 /* If new queue belongs to different cfq_group, don't choose it */
1819 if (cur_cfqq->cfqg != cfqq->cfqg)
1823 * It only makes sense to merge sync queues.
1825 if (!cfq_cfqq_sync(cfqq))
1827 if (CFQQ_SEEKY(cfqq))
1831 * Do not merge queues of different priority classes
1833 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1840 * Determine whether we should enforce idle window for this queue.
1843 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1845 enum wl_prio_t prio = cfqq_prio(cfqq);
1846 struct cfq_rb_root *service_tree = cfqq->service_tree;
1848 BUG_ON(!service_tree);
1849 BUG_ON(!service_tree->count);
1851 /* We never do for idle class queues. */
1852 if (prio == IDLE_WORKLOAD)
1855 /* We do for queues that were marked with idle window flag. */
1856 if (cfq_cfqq_idle_window(cfqq) &&
1857 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1861 * Otherwise, we do only if they are the last ones
1862 * in their service tree.
1864 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1866 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1867 service_tree->count);
1871 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1873 struct cfq_queue *cfqq = cfqd->active_queue;
1874 struct cfq_io_context *cic;
1878 * SSD device without seek penalty, disable idling. But only do so
1879 * for devices that support queuing, otherwise we still have a problem
1880 * with sync vs async workloads.
1882 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1885 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1886 WARN_ON(cfq_cfqq_slice_new(cfqq));
1889 * idle is disabled, either manually or by past process history
1891 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
1895 * still active requests from this queue, don't idle
1897 if (cfqq->dispatched)
1901 * task has exited, don't wait
1903 cic = cfqd->active_cic;
1904 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1908 * If our average think time is larger than the remaining time
1909 * slice, then don't idle. This avoids overrunning the allotted
1912 if (sample_valid(cic->ttime_samples) &&
1913 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1914 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1919 cfq_mark_cfqq_wait_request(cfqq);
1921 sl = cfqd->cfq_slice_idle;
1923 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1924 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1925 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1929 * Move request from internal lists to the request queue dispatch list.
1931 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1933 struct cfq_data *cfqd = q->elevator->elevator_data;
1934 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1936 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1938 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1939 cfq_remove_request(rq);
1941 elv_dispatch_sort(q, rq);
1943 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1944 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1945 rq_data_dir(rq), rq_is_sync(rq));
1949 * return expired entry, or NULL to just start from scratch in rbtree
1951 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1953 struct request *rq = NULL;
1955 if (cfq_cfqq_fifo_expire(cfqq))
1958 cfq_mark_cfqq_fifo_expire(cfqq);
1960 if (list_empty(&cfqq->fifo))
1963 rq = rq_entry_fifo(cfqq->fifo.next);
1964 if (time_before(jiffies, rq_fifo_time(rq)))
1967 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1972 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1974 const int base_rq = cfqd->cfq_slice_async_rq;
1976 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1978 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1982 * Must be called with the queue_lock held.
1984 static int cfqq_process_refs(struct cfq_queue *cfqq)
1986 int process_refs, io_refs;
1988 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
1989 process_refs = atomic_read(&cfqq->ref) - io_refs;
1990 BUG_ON(process_refs < 0);
1991 return process_refs;
1994 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
1996 int process_refs, new_process_refs;
1997 struct cfq_queue *__cfqq;
2000 * If there are no process references on the new_cfqq, then it is
2001 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2002 * chain may have dropped their last reference (not just their
2003 * last process reference).
2005 if (!cfqq_process_refs(new_cfqq))
2008 /* Avoid a circular list and skip interim queue merges */
2009 while ((__cfqq = new_cfqq->new_cfqq)) {
2015 process_refs = cfqq_process_refs(cfqq);
2016 new_process_refs = cfqq_process_refs(new_cfqq);
2018 * If the process for the cfqq has gone away, there is no
2019 * sense in merging the queues.
2021 if (process_refs == 0 || new_process_refs == 0)
2025 * Merge in the direction of the lesser amount of work.
2027 if (new_process_refs >= process_refs) {
2028 cfqq->new_cfqq = new_cfqq;
2029 atomic_add(process_refs, &new_cfqq->ref);
2031 new_cfqq->new_cfqq = cfqq;
2032 atomic_add(new_process_refs, &cfqq->ref);
2036 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2037 struct cfq_group *cfqg, enum wl_prio_t prio)
2039 struct cfq_queue *queue;
2041 bool key_valid = false;
2042 unsigned long lowest_key = 0;
2043 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2045 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2046 /* select the one with lowest rb_key */
2047 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2049 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2050 lowest_key = queue->rb_key;
2059 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2063 struct cfq_rb_root *st;
2064 unsigned group_slice;
2067 cfqd->serving_prio = IDLE_WORKLOAD;
2068 cfqd->workload_expires = jiffies + 1;
2072 /* Choose next priority. RT > BE > IDLE */
2073 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2074 cfqd->serving_prio = RT_WORKLOAD;
2075 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2076 cfqd->serving_prio = BE_WORKLOAD;
2078 cfqd->serving_prio = IDLE_WORKLOAD;
2079 cfqd->workload_expires = jiffies + 1;
2084 * For RT and BE, we have to choose also the type
2085 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2088 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2092 * check workload expiration, and that we still have other queues ready
2094 if (count && !time_after(jiffies, cfqd->workload_expires))
2097 /* otherwise select new workload type */
2098 cfqd->serving_type =
2099 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2100 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2104 * the workload slice is computed as a fraction of target latency
2105 * proportional to the number of queues in that workload, over
2106 * all the queues in the same priority class
2108 group_slice = cfq_group_slice(cfqd, cfqg);
2110 slice = group_slice * count /
2111 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2112 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2114 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2118 * Async queues are currently system wide. Just taking
2119 * proportion of queues with-in same group will lead to higher
2120 * async ratio system wide as generally root group is going
2121 * to have higher weight. A more accurate thing would be to
2122 * calculate system wide asnc/sync ratio.
2124 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2125 tmp = tmp/cfqd->busy_queues;
2126 slice = min_t(unsigned, slice, tmp);
2128 /* async workload slice is scaled down according to
2129 * the sync/async slice ratio. */
2130 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2132 /* sync workload slice is at least 2 * cfq_slice_idle */
2133 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2135 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2136 cfq_log(cfqd, "workload slice:%d", slice);
2137 cfqd->workload_expires = jiffies + slice;
2140 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2142 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2143 struct cfq_group *cfqg;
2145 if (RB_EMPTY_ROOT(&st->rb))
2147 cfqg = cfq_rb_first_group(st);
2148 st->active = &cfqg->rb_node;
2149 update_min_vdisktime(st);
2153 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2155 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2157 cfqd->serving_group = cfqg;
2159 /* Restore the workload type data */
2160 if (cfqg->saved_workload_slice) {
2161 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2162 cfqd->serving_type = cfqg->saved_workload;
2163 cfqd->serving_prio = cfqg->saved_serving_prio;
2165 cfqd->workload_expires = jiffies - 1;
2167 choose_service_tree(cfqd, cfqg);
2171 * Select a queue for service. If we have a current active queue,
2172 * check whether to continue servicing it, or retrieve and set a new one.
2174 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2176 struct cfq_queue *cfqq, *new_cfqq = NULL;
2178 cfqq = cfqd->active_queue;
2182 if (!cfqd->rq_queued)
2186 * We were waiting for group to get backlogged. Expire the queue
2188 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2192 * The active queue has run out of time, expire it and select new.
2194 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2196 * If slice had not expired at the completion of last request
2197 * we might not have turned on wait_busy flag. Don't expire
2198 * the queue yet. Allow the group to get backlogged.
2200 * The very fact that we have used the slice, that means we
2201 * have been idling all along on this queue and it should be
2202 * ok to wait for this request to complete.
2204 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2205 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2213 * The active queue has requests and isn't expired, allow it to
2216 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2220 * If another queue has a request waiting within our mean seek
2221 * distance, let it run. The expire code will check for close
2222 * cooperators and put the close queue at the front of the service
2223 * tree. If possible, merge the expiring queue with the new cfqq.
2225 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2227 if (!cfqq->new_cfqq)
2228 cfq_setup_merge(cfqq, new_cfqq);
2233 * No requests pending. If the active queue still has requests in
2234 * flight or is idling for a new request, allow either of these
2235 * conditions to happen (or time out) before selecting a new queue.
2237 if (timer_pending(&cfqd->idle_slice_timer) ||
2238 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
2244 cfq_slice_expired(cfqd, 0);
2247 * Current queue expired. Check if we have to switch to a new
2251 cfq_choose_cfqg(cfqd);
2253 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2258 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2262 while (cfqq->next_rq) {
2263 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2267 BUG_ON(!list_empty(&cfqq->fifo));
2269 /* By default cfqq is not expired if it is empty. Do it explicitly */
2270 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2275 * Drain our current requests. Used for barriers and when switching
2276 * io schedulers on-the-fly.
2278 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2280 struct cfq_queue *cfqq;
2283 /* Expire the timeslice of the current active queue first */
2284 cfq_slice_expired(cfqd, 0);
2285 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2286 __cfq_set_active_queue(cfqd, cfqq);
2287 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2290 BUG_ON(cfqd->busy_queues);
2292 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2296 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2297 struct cfq_queue *cfqq)
2299 /* the queue hasn't finished any request, can't estimate */
2300 if (cfq_cfqq_slice_new(cfqq))
2302 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2309 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2311 unsigned int max_dispatch;
2314 * Drain async requests before we start sync IO
2316 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2320 * If this is an async queue and we have sync IO in flight, let it wait
2322 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2325 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2326 if (cfq_class_idle(cfqq))
2330 * Does this cfqq already have too much IO in flight?
2332 if (cfqq->dispatched >= max_dispatch) {
2334 * idle queue must always only have a single IO in flight
2336 if (cfq_class_idle(cfqq))
2340 * We have other queues, don't allow more IO from this one
2342 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
2346 * Sole queue user, no limit
2348 if (cfqd->busy_queues == 1)
2352 * Normally we start throttling cfqq when cfq_quantum/2
2353 * requests have been dispatched. But we can drive
2354 * deeper queue depths at the beginning of slice
2355 * subjected to upper limit of cfq_quantum.
2357 max_dispatch = cfqd->cfq_quantum;
2361 * Async queues must wait a bit before being allowed dispatch.
2362 * We also ramp up the dispatch depth gradually for async IO,
2363 * based on the last sync IO we serviced
2365 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2366 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2369 depth = last_sync / cfqd->cfq_slice[1];
2370 if (!depth && !cfqq->dispatched)
2372 if (depth < max_dispatch)
2373 max_dispatch = depth;
2377 * If we're below the current max, allow a dispatch
2379 return cfqq->dispatched < max_dispatch;
2383 * Dispatch a request from cfqq, moving them to the request queue
2386 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2390 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2392 if (!cfq_may_dispatch(cfqd, cfqq))
2396 * follow expired path, else get first next available
2398 rq = cfq_check_fifo(cfqq);
2403 * insert request into driver dispatch list
2405 cfq_dispatch_insert(cfqd->queue, rq);
2407 if (!cfqd->active_cic) {
2408 struct cfq_io_context *cic = RQ_CIC(rq);
2410 atomic_long_inc(&cic->ioc->refcount);
2411 cfqd->active_cic = cic;
2418 * Find the cfqq that we need to service and move a request from that to the
2421 static int cfq_dispatch_requests(struct request_queue *q, int force)
2423 struct cfq_data *cfqd = q->elevator->elevator_data;
2424 struct cfq_queue *cfqq;
2426 if (!cfqd->busy_queues)
2429 if (unlikely(force))
2430 return cfq_forced_dispatch(cfqd);
2432 cfqq = cfq_select_queue(cfqd);
2437 * Dispatch a request from this cfqq, if it is allowed
2439 if (!cfq_dispatch_request(cfqd, cfqq))
2442 cfqq->slice_dispatch++;
2443 cfq_clear_cfqq_must_dispatch(cfqq);
2446 * expire an async queue immediately if it has used up its slice. idle
2447 * queue always expire after 1 dispatch round.
2449 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2450 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2451 cfq_class_idle(cfqq))) {
2452 cfqq->slice_end = jiffies + 1;
2453 cfq_slice_expired(cfqd, 0);
2456 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2461 * task holds one reference to the queue, dropped when task exits. each rq
2462 * in-flight on this queue also holds a reference, dropped when rq is freed.
2464 * Each cfq queue took a reference on the parent group. Drop it now.
2465 * queue lock must be held here.
2467 static void cfq_put_queue(struct cfq_queue *cfqq)
2469 struct cfq_data *cfqd = cfqq->cfqd;
2470 struct cfq_group *cfqg, *orig_cfqg;
2472 BUG_ON(atomic_read(&cfqq->ref) <= 0);
2474 if (!atomic_dec_and_test(&cfqq->ref))
2477 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2478 BUG_ON(rb_first(&cfqq->sort_list));
2479 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2481 orig_cfqg = cfqq->orig_cfqg;
2483 if (unlikely(cfqd->active_queue == cfqq)) {
2484 __cfq_slice_expired(cfqd, cfqq, 0);
2485 cfq_schedule_dispatch(cfqd);
2488 BUG_ON(cfq_cfqq_on_rr(cfqq));
2489 kmem_cache_free(cfq_pool, cfqq);
2492 cfq_put_cfqg(orig_cfqg);
2496 * Must always be called with the rcu_read_lock() held
2499 __call_for_each_cic(struct io_context *ioc,
2500 void (*func)(struct io_context *, struct cfq_io_context *))
2502 struct cfq_io_context *cic;
2503 struct hlist_node *n;
2505 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2510 * Call func for each cic attached to this ioc.
2513 call_for_each_cic(struct io_context *ioc,
2514 void (*func)(struct io_context *, struct cfq_io_context *))
2517 __call_for_each_cic(ioc, func);
2521 static void cfq_cic_free_rcu(struct rcu_head *head)
2523 struct cfq_io_context *cic;
2525 cic = container_of(head, struct cfq_io_context, rcu_head);
2527 kmem_cache_free(cfq_ioc_pool, cic);
2528 elv_ioc_count_dec(cfq_ioc_count);
2532 * CFQ scheduler is exiting, grab exit lock and check
2533 * the pending io context count. If it hits zero,
2534 * complete ioc_gone and set it back to NULL
2536 spin_lock(&ioc_gone_lock);
2537 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2541 spin_unlock(&ioc_gone_lock);
2545 static void cfq_cic_free(struct cfq_io_context *cic)
2547 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2550 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2552 unsigned long flags;
2553 unsigned long dead_key = (unsigned long) cic->key;
2555 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2557 spin_lock_irqsave(&ioc->lock, flags);
2558 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2559 hlist_del_rcu(&cic->cic_list);
2560 spin_unlock_irqrestore(&ioc->lock, flags);
2566 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2567 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2568 * and ->trim() which is called with the task lock held
2570 static void cfq_free_io_context(struct io_context *ioc)
2573 * ioc->refcount is zero here, or we are called from elv_unregister(),
2574 * so no more cic's are allowed to be linked into this ioc. So it
2575 * should be ok to iterate over the known list, we will see all cic's
2576 * since no new ones are added.
2578 __call_for_each_cic(ioc, cic_free_func);
2581 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2583 struct cfq_queue *__cfqq, *next;
2586 * If this queue was scheduled to merge with another queue, be
2587 * sure to drop the reference taken on that queue (and others in
2588 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2590 __cfqq = cfqq->new_cfqq;
2592 if (__cfqq == cfqq) {
2593 WARN(1, "cfqq->new_cfqq loop detected\n");
2596 next = __cfqq->new_cfqq;
2597 cfq_put_queue(__cfqq);
2602 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2604 if (unlikely(cfqq == cfqd->active_queue)) {
2605 __cfq_slice_expired(cfqd, cfqq, 0);
2606 cfq_schedule_dispatch(cfqd);
2609 cfq_put_cooperator(cfqq);
2611 cfq_put_queue(cfqq);
2614 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2615 struct cfq_io_context *cic)
2617 struct io_context *ioc = cic->ioc;
2619 list_del_init(&cic->queue_list);
2622 * Make sure dead mark is seen for dead queues
2625 cic->key = cfqd_dead_key(cfqd);
2627 if (ioc->ioc_data == cic)
2628 rcu_assign_pointer(ioc->ioc_data, NULL);
2630 if (cic->cfqq[BLK_RW_ASYNC]) {
2631 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2632 cic->cfqq[BLK_RW_ASYNC] = NULL;
2635 if (cic->cfqq[BLK_RW_SYNC]) {
2636 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2637 cic->cfqq[BLK_RW_SYNC] = NULL;
2641 static void cfq_exit_single_io_context(struct io_context *ioc,
2642 struct cfq_io_context *cic)
2644 struct cfq_data *cfqd = cic_to_cfqd(cic);
2647 struct request_queue *q = cfqd->queue;
2648 unsigned long flags;
2650 spin_lock_irqsave(q->queue_lock, flags);
2653 * Ensure we get a fresh copy of the ->key to prevent
2654 * race between exiting task and queue
2656 smp_read_barrier_depends();
2657 if (cic->key == cfqd)
2658 __cfq_exit_single_io_context(cfqd, cic);
2660 spin_unlock_irqrestore(q->queue_lock, flags);
2665 * The process that ioc belongs to has exited, we need to clean up
2666 * and put the internal structures we have that belongs to that process.
2668 static void cfq_exit_io_context(struct io_context *ioc)
2670 call_for_each_cic(ioc, cfq_exit_single_io_context);
2673 static struct cfq_io_context *
2674 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2676 struct cfq_io_context *cic;
2678 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2681 cic->last_end_request = jiffies;
2682 INIT_LIST_HEAD(&cic->queue_list);
2683 INIT_HLIST_NODE(&cic->cic_list);
2684 cic->dtor = cfq_free_io_context;
2685 cic->exit = cfq_exit_io_context;
2686 elv_ioc_count_inc(cfq_ioc_count);
2692 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2694 struct task_struct *tsk = current;
2697 if (!cfq_cfqq_prio_changed(cfqq))
2700 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2701 switch (ioprio_class) {
2703 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2704 case IOPRIO_CLASS_NONE:
2706 * no prio set, inherit CPU scheduling settings
2708 cfqq->ioprio = task_nice_ioprio(tsk);
2709 cfqq->ioprio_class = task_nice_ioclass(tsk);
2711 case IOPRIO_CLASS_RT:
2712 cfqq->ioprio = task_ioprio(ioc);
2713 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2715 case IOPRIO_CLASS_BE:
2716 cfqq->ioprio = task_ioprio(ioc);
2717 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2719 case IOPRIO_CLASS_IDLE:
2720 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2722 cfq_clear_cfqq_idle_window(cfqq);
2727 * keep track of original prio settings in case we have to temporarily
2728 * elevate the priority of this queue
2730 cfqq->org_ioprio = cfqq->ioprio;
2731 cfqq->org_ioprio_class = cfqq->ioprio_class;
2732 cfq_clear_cfqq_prio_changed(cfqq);
2735 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2737 struct cfq_data *cfqd = cic_to_cfqd(cic);
2738 struct cfq_queue *cfqq;
2739 unsigned long flags;
2741 if (unlikely(!cfqd))
2744 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2746 cfqq = cic->cfqq[BLK_RW_ASYNC];
2748 struct cfq_queue *new_cfqq;
2749 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2752 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2753 cfq_put_queue(cfqq);
2757 cfqq = cic->cfqq[BLK_RW_SYNC];
2759 cfq_mark_cfqq_prio_changed(cfqq);
2761 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2764 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2766 call_for_each_cic(ioc, changed_ioprio);
2767 ioc->ioprio_changed = 0;
2770 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2771 pid_t pid, bool is_sync)
2773 RB_CLEAR_NODE(&cfqq->rb_node);
2774 RB_CLEAR_NODE(&cfqq->p_node);
2775 INIT_LIST_HEAD(&cfqq->fifo);
2777 atomic_set(&cfqq->ref, 0);
2780 cfq_mark_cfqq_prio_changed(cfqq);
2783 if (!cfq_class_idle(cfqq))
2784 cfq_mark_cfqq_idle_window(cfqq);
2785 cfq_mark_cfqq_sync(cfqq);
2790 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2791 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2793 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2794 struct cfq_data *cfqd = cic_to_cfqd(cic);
2795 unsigned long flags;
2796 struct request_queue *q;
2798 if (unlikely(!cfqd))
2803 spin_lock_irqsave(q->queue_lock, flags);
2807 * Drop reference to sync queue. A new sync queue will be
2808 * assigned in new group upon arrival of a fresh request.
2810 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2811 cic_set_cfqq(cic, NULL, 1);
2812 cfq_put_queue(sync_cfqq);
2815 spin_unlock_irqrestore(q->queue_lock, flags);
2818 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2820 call_for_each_cic(ioc, changed_cgroup);
2821 ioc->cgroup_changed = 0;
2823 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2825 static struct cfq_queue *
2826 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2827 struct io_context *ioc, gfp_t gfp_mask)
2829 struct cfq_queue *cfqq, *new_cfqq = NULL;
2830 struct cfq_io_context *cic;
2831 struct cfq_group *cfqg;
2834 cfqg = cfq_get_cfqg(cfqd, 1);
2835 cic = cfq_cic_lookup(cfqd, ioc);
2836 /* cic always exists here */
2837 cfqq = cic_to_cfqq(cic, is_sync);
2840 * Always try a new alloc if we fell back to the OOM cfqq
2841 * originally, since it should just be a temporary situation.
2843 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2848 } else if (gfp_mask & __GFP_WAIT) {
2849 spin_unlock_irq(cfqd->queue->queue_lock);
2850 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2851 gfp_mask | __GFP_ZERO,
2853 spin_lock_irq(cfqd->queue->queue_lock);
2857 cfqq = kmem_cache_alloc_node(cfq_pool,
2858 gfp_mask | __GFP_ZERO,
2863 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2864 cfq_init_prio_data(cfqq, ioc);
2865 cfq_link_cfqq_cfqg(cfqq, cfqg);
2866 cfq_log_cfqq(cfqd, cfqq, "alloced");
2868 cfqq = &cfqd->oom_cfqq;
2872 kmem_cache_free(cfq_pool, new_cfqq);
2877 static struct cfq_queue **
2878 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2880 switch (ioprio_class) {
2881 case IOPRIO_CLASS_RT:
2882 return &cfqd->async_cfqq[0][ioprio];
2883 case IOPRIO_CLASS_BE:
2884 return &cfqd->async_cfqq[1][ioprio];
2885 case IOPRIO_CLASS_IDLE:
2886 return &cfqd->async_idle_cfqq;
2892 static struct cfq_queue *
2893 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2896 const int ioprio = task_ioprio(ioc);
2897 const int ioprio_class = task_ioprio_class(ioc);
2898 struct cfq_queue **async_cfqq = NULL;
2899 struct cfq_queue *cfqq = NULL;
2902 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2907 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2910 * pin the queue now that it's allocated, scheduler exit will prune it
2912 if (!is_sync && !(*async_cfqq)) {
2913 atomic_inc(&cfqq->ref);
2917 atomic_inc(&cfqq->ref);
2922 * We drop cfq io contexts lazily, so we may find a dead one.
2925 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2926 struct cfq_io_context *cic)
2928 unsigned long flags;
2930 WARN_ON(!list_empty(&cic->queue_list));
2931 BUG_ON(cic->key != cfqd_dead_key(cfqd));
2933 spin_lock_irqsave(&ioc->lock, flags);
2935 BUG_ON(ioc->ioc_data == cic);
2937 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
2938 hlist_del_rcu(&cic->cic_list);
2939 spin_unlock_irqrestore(&ioc->lock, flags);
2944 static struct cfq_io_context *
2945 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
2947 struct cfq_io_context *cic;
2948 unsigned long flags;
2956 * we maintain a last-hit cache, to avoid browsing over the tree
2958 cic = rcu_dereference(ioc->ioc_data);
2959 if (cic && cic->key == cfqd) {
2965 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
2969 if (unlikely(cic->key != cfqd)) {
2970 cfq_drop_dead_cic(cfqd, ioc, cic);
2975 spin_lock_irqsave(&ioc->lock, flags);
2976 rcu_assign_pointer(ioc->ioc_data, cic);
2977 spin_unlock_irqrestore(&ioc->lock, flags);
2985 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2986 * the process specific cfq io context when entered from the block layer.
2987 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2989 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
2990 struct cfq_io_context *cic, gfp_t gfp_mask)
2992 unsigned long flags;
2995 ret = radix_tree_preload(gfp_mask);
3000 spin_lock_irqsave(&ioc->lock, flags);
3001 ret = radix_tree_insert(&ioc->radix_root,
3002 cfqd->cic_index, cic);
3004 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3005 spin_unlock_irqrestore(&ioc->lock, flags);
3007 radix_tree_preload_end();
3010 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3011 list_add(&cic->queue_list, &cfqd->cic_list);
3012 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3017 printk(KERN_ERR "cfq: cic link failed!\n");
3023 * Setup general io context and cfq io context. There can be several cfq
3024 * io contexts per general io context, if this process is doing io to more
3025 * than one device managed by cfq.
3027 static struct cfq_io_context *
3028 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3030 struct io_context *ioc = NULL;
3031 struct cfq_io_context *cic;
3033 might_sleep_if(gfp_mask & __GFP_WAIT);
3035 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3039 cic = cfq_cic_lookup(cfqd, ioc);
3043 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3047 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3051 smp_read_barrier_depends();
3052 if (unlikely(ioc->ioprio_changed))
3053 cfq_ioc_set_ioprio(ioc);
3055 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3056 if (unlikely(ioc->cgroup_changed))
3057 cfq_ioc_set_cgroup(ioc);
3063 put_io_context(ioc);
3068 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3070 unsigned long elapsed = jiffies - cic->last_end_request;
3071 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3073 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3074 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3075 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3079 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3083 sector_t n_sec = blk_rq_sectors(rq);
3084 if (cfqq->last_request_pos) {
3085 if (cfqq->last_request_pos < blk_rq_pos(rq))
3086 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3088 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3091 cfqq->seek_history <<= 1;
3092 if (blk_queue_nonrot(cfqd->queue))
3093 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3095 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3099 * Disable idle window if the process thinks too long or seeks so much that
3103 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3104 struct cfq_io_context *cic)
3106 int old_idle, enable_idle;
3109 * Don't idle for async or idle io prio class
3111 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3114 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3116 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3117 cfq_mark_cfqq_deep(cfqq);
3119 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3121 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3122 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3124 else if (sample_valid(cic->ttime_samples)) {
3125 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3131 if (old_idle != enable_idle) {
3132 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3134 cfq_mark_cfqq_idle_window(cfqq);
3136 cfq_clear_cfqq_idle_window(cfqq);
3141 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3142 * no or if we aren't sure, a 1 will cause a preempt.
3145 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3148 struct cfq_queue *cfqq;
3150 cfqq = cfqd->active_queue;
3154 if (cfq_class_idle(new_cfqq))
3157 if (cfq_class_idle(cfqq))
3161 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3163 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3167 * if the new request is sync, but the currently running queue is
3168 * not, let the sync request have priority.
3170 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3173 if (new_cfqq->cfqg != cfqq->cfqg)
3176 if (cfq_slice_used(cfqq))
3179 /* Allow preemption only if we are idling on sync-noidle tree */
3180 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3181 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3182 new_cfqq->service_tree->count == 2 &&
3183 RB_EMPTY_ROOT(&cfqq->sort_list))
3187 * So both queues are sync. Let the new request get disk time if
3188 * it's a metadata request and the current queue is doing regular IO.
3190 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3194 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3196 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3199 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3203 * if this request is as-good as one we would expect from the
3204 * current cfqq, let it preempt
3206 if (cfq_rq_close(cfqd, cfqq, rq))
3213 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3214 * let it have half of its nominal slice.
3216 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3218 cfq_log_cfqq(cfqd, cfqq, "preempt");
3219 cfq_slice_expired(cfqd, 1);
3222 * Put the new queue at the front of the of the current list,
3223 * so we know that it will be selected next.
3225 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3227 cfq_service_tree_add(cfqd, cfqq, 1);
3229 cfqq->slice_end = 0;
3230 cfq_mark_cfqq_slice_new(cfqq);
3234 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3235 * something we should do about it
3238 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3241 struct cfq_io_context *cic = RQ_CIC(rq);
3244 if (rq->cmd_flags & REQ_META)
3245 cfqq->meta_pending++;
3247 cfq_update_io_thinktime(cfqd, cic);
3248 cfq_update_io_seektime(cfqd, cfqq, rq);
3249 cfq_update_idle_window(cfqd, cfqq, cic);
3251 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3253 if (cfqq == cfqd->active_queue) {
3255 * Remember that we saw a request from this process, but
3256 * don't start queuing just yet. Otherwise we risk seeing lots
3257 * of tiny requests, because we disrupt the normal plugging
3258 * and merging. If the request is already larger than a single
3259 * page, let it rip immediately. For that case we assume that
3260 * merging is already done. Ditto for a busy system that
3261 * has other work pending, don't risk delaying until the
3262 * idle timer unplug to continue working.
3264 if (cfq_cfqq_wait_request(cfqq)) {
3265 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3266 cfqd->busy_queues > 1) {
3267 cfq_del_timer(cfqd, cfqq);
3268 cfq_clear_cfqq_wait_request(cfqq);
3269 __blk_run_queue(cfqd->queue);
3271 cfq_blkiocg_update_idle_time_stats(
3273 cfq_mark_cfqq_must_dispatch(cfqq);
3276 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3278 * not the active queue - expire current slice if it is
3279 * idle and has expired it's mean thinktime or this new queue
3280 * has some old slice time left and is of higher priority or
3281 * this new queue is RT and the current one is BE
3283 cfq_preempt_queue(cfqd, cfqq);
3284 __blk_run_queue(cfqd->queue);
3288 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3290 struct cfq_data *cfqd = q->elevator->elevator_data;
3291 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3293 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3294 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3296 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3297 list_add_tail(&rq->queuelist, &cfqq->fifo);
3299 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3300 &cfqd->serving_group->blkg, rq_data_dir(rq),
3302 cfq_rq_enqueued(cfqd, cfqq, rq);
3306 * Update hw_tag based on peak queue depth over 50 samples under
3309 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3311 struct cfq_queue *cfqq = cfqd->active_queue;
3313 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3314 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3316 if (cfqd->hw_tag == 1)
3319 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3320 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3324 * If active queue hasn't enough requests and can idle, cfq might not
3325 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3328 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3329 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3330 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3333 if (cfqd->hw_tag_samples++ < 50)
3336 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3342 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3344 struct cfq_io_context *cic = cfqd->active_cic;
3346 /* If there are other queues in the group, don't wait */
3347 if (cfqq->cfqg->nr_cfqq > 1)
3350 if (cfq_slice_used(cfqq))
3353 /* if slice left is less than think time, wait busy */
3354 if (cic && sample_valid(cic->ttime_samples)
3355 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3359 * If think times is less than a jiffy than ttime_mean=0 and above
3360 * will not be true. It might happen that slice has not expired yet
3361 * but will expire soon (4-5 ns) during select_queue(). To cover the
3362 * case where think time is less than a jiffy, mark the queue wait
3363 * busy if only 1 jiffy is left in the slice.
3365 if (cfqq->slice_end - jiffies == 1)
3371 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3373 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3374 struct cfq_data *cfqd = cfqq->cfqd;
3375 const int sync = rq_is_sync(rq);
3379 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3380 !!(rq->cmd_flags & REQ_NOIDLE));
3382 cfq_update_hw_tag(cfqd);
3384 WARN_ON(!cfqd->rq_in_driver);
3385 WARN_ON(!cfqq->dispatched);
3386 cfqd->rq_in_driver--;
3388 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3389 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3390 rq_data_dir(rq), rq_is_sync(rq));
3392 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3395 RQ_CIC(rq)->last_end_request = now;
3396 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3397 cfqd->last_delayed_sync = now;
3401 * If this is the active queue, check if it needs to be expired,
3402 * or if we want to idle in case it has no pending requests.
3404 if (cfqd->active_queue == cfqq) {
3405 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3407 if (cfq_cfqq_slice_new(cfqq)) {
3408 cfq_set_prio_slice(cfqd, cfqq);
3409 cfq_clear_cfqq_slice_new(cfqq);
3413 * Should we wait for next request to come in before we expire
3416 if (cfq_should_wait_busy(cfqd, cfqq)) {
3417 cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
3418 cfq_mark_cfqq_wait_busy(cfqq);
3419 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3423 * Idling is not enabled on:
3425 * - idle-priority queues
3427 * - queues with still some requests queued
3428 * - when there is a close cooperator
3430 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3431 cfq_slice_expired(cfqd, 1);
3432 else if (sync && cfqq_empty &&
3433 !cfq_close_cooperator(cfqd, cfqq)) {
3434 cfq_arm_slice_timer(cfqd);
3438 if (!cfqd->rq_in_driver)
3439 cfq_schedule_dispatch(cfqd);
3443 * we temporarily boost lower priority queues if they are holding fs exclusive
3444 * resources. they are boosted to normal prio (CLASS_BE/4)
3446 static void cfq_prio_boost(struct cfq_queue *cfqq)
3448 if (has_fs_excl()) {
3450 * boost idle prio on transactions that would lock out other
3451 * users of the filesystem
3453 if (cfq_class_idle(cfqq))
3454 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3455 if (cfqq->ioprio > IOPRIO_NORM)
3456 cfqq->ioprio = IOPRIO_NORM;
3459 * unboost the queue (if needed)
3461 cfqq->ioprio_class = cfqq->org_ioprio_class;
3462 cfqq->ioprio = cfqq->org_ioprio;
3466 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3468 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3469 cfq_mark_cfqq_must_alloc_slice(cfqq);
3470 return ELV_MQUEUE_MUST;
3473 return ELV_MQUEUE_MAY;
3476 static int cfq_may_queue(struct request_queue *q, int rw)
3478 struct cfq_data *cfqd = q->elevator->elevator_data;
3479 struct task_struct *tsk = current;
3480 struct cfq_io_context *cic;
3481 struct cfq_queue *cfqq;
3484 * don't force setup of a queue from here, as a call to may_queue
3485 * does not necessarily imply that a request actually will be queued.
3486 * so just lookup a possibly existing queue, or return 'may queue'
3489 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3491 return ELV_MQUEUE_MAY;
3493 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3495 cfq_init_prio_data(cfqq, cic->ioc);
3496 cfq_prio_boost(cfqq);
3498 return __cfq_may_queue(cfqq);
3501 return ELV_MQUEUE_MAY;
3505 * queue lock held here
3507 static void cfq_put_request(struct request *rq)
3509 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3512 const int rw = rq_data_dir(rq);
3514 BUG_ON(!cfqq->allocated[rw]);
3515 cfqq->allocated[rw]--;
3517 put_io_context(RQ_CIC(rq)->ioc);
3519 rq->elevator_private = NULL;
3520 rq->elevator_private2 = NULL;
3522 /* Put down rq reference on cfqg */
3523 cfq_put_cfqg(RQ_CFQG(rq));
3524 rq->elevator_private3 = NULL;
3526 cfq_put_queue(cfqq);
3530 static struct cfq_queue *
3531 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3532 struct cfq_queue *cfqq)
3534 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3535 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3536 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3537 cfq_put_queue(cfqq);
3538 return cic_to_cfqq(cic, 1);
3542 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3543 * was the last process referring to said cfqq.
3545 static struct cfq_queue *
3546 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3548 if (cfqq_process_refs(cfqq) == 1) {
3549 cfqq->pid = current->pid;
3550 cfq_clear_cfqq_coop(cfqq);
3551 cfq_clear_cfqq_split_coop(cfqq);
3555 cic_set_cfqq(cic, NULL, 1);
3557 cfq_put_cooperator(cfqq);
3559 cfq_put_queue(cfqq);
3563 * Allocate cfq data structures associated with this request.
3566 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3568 struct cfq_data *cfqd = q->elevator->elevator_data;
3569 struct cfq_io_context *cic;
3570 const int rw = rq_data_dir(rq);
3571 const bool is_sync = rq_is_sync(rq);
3572 struct cfq_queue *cfqq;
3573 unsigned long flags;
3575 might_sleep_if(gfp_mask & __GFP_WAIT);
3577 cic = cfq_get_io_context(cfqd, gfp_mask);
3579 spin_lock_irqsave(q->queue_lock, flags);
3585 cfqq = cic_to_cfqq(cic, is_sync);
3586 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3587 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3588 cic_set_cfqq(cic, cfqq, is_sync);
3591 * If the queue was seeky for too long, break it apart.
3593 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3594 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3595 cfqq = split_cfqq(cic, cfqq);
3601 * Check to see if this queue is scheduled to merge with
3602 * another, closely cooperating queue. The merging of
3603 * queues happens here as it must be done in process context.
3604 * The reference on new_cfqq was taken in merge_cfqqs.
3607 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3610 cfqq->allocated[rw]++;
3611 atomic_inc(&cfqq->ref);
3613 spin_unlock_irqrestore(q->queue_lock, flags);
3615 rq->elevator_private = cic;
3616 rq->elevator_private2 = cfqq;
3617 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
3622 put_io_context(cic->ioc);
3624 cfq_schedule_dispatch(cfqd);
3625 spin_unlock_irqrestore(q->queue_lock, flags);
3626 cfq_log(cfqd, "set_request fail");
3630 static void cfq_kick_queue(struct work_struct *work)
3632 struct cfq_data *cfqd =
3633 container_of(work, struct cfq_data, unplug_work);
3634 struct request_queue *q = cfqd->queue;
3636 spin_lock_irq(q->queue_lock);
3637 __blk_run_queue(cfqd->queue);
3638 spin_unlock_irq(q->queue_lock);
3642 * Timer running if the active_queue is currently idling inside its time slice
3644 static void cfq_idle_slice_timer(unsigned long data)
3646 struct cfq_data *cfqd = (struct cfq_data *) data;
3647 struct cfq_queue *cfqq;
3648 unsigned long flags;
3651 cfq_log(cfqd, "idle timer fired");
3653 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3655 cfqq = cfqd->active_queue;
3660 * We saw a request before the queue expired, let it through
3662 if (cfq_cfqq_must_dispatch(cfqq))
3668 if (cfq_slice_used(cfqq))
3672 * only expire and reinvoke request handler, if there are
3673 * other queues with pending requests
3675 if (!cfqd->busy_queues)
3679 * not expired and it has a request pending, let it dispatch
3681 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3685 * Queue depth flag is reset only when the idle didn't succeed
3687 cfq_clear_cfqq_deep(cfqq);
3690 cfq_slice_expired(cfqd, timed_out);
3692 cfq_schedule_dispatch(cfqd);
3694 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3697 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3699 del_timer_sync(&cfqd->idle_slice_timer);
3700 cancel_work_sync(&cfqd->unplug_work);
3703 static void cfq_put_async_queues(struct cfq_data *cfqd)
3707 for (i = 0; i < IOPRIO_BE_NR; i++) {
3708 if (cfqd->async_cfqq[0][i])
3709 cfq_put_queue(cfqd->async_cfqq[0][i]);
3710 if (cfqd->async_cfqq[1][i])
3711 cfq_put_queue(cfqd->async_cfqq[1][i]);
3714 if (cfqd->async_idle_cfqq)
3715 cfq_put_queue(cfqd->async_idle_cfqq);
3718 static void cfq_cfqd_free(struct rcu_head *head)
3720 kfree(container_of(head, struct cfq_data, rcu));
3723 static void cfq_exit_queue(struct elevator_queue *e)
3725 struct cfq_data *cfqd = e->elevator_data;
3726 struct request_queue *q = cfqd->queue;
3728 cfq_shutdown_timer_wq(cfqd);
3730 spin_lock_irq(q->queue_lock);
3732 if (cfqd->active_queue)
3733 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3735 while (!list_empty(&cfqd->cic_list)) {
3736 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3737 struct cfq_io_context,
3740 __cfq_exit_single_io_context(cfqd, cic);
3743 cfq_put_async_queues(cfqd);
3744 cfq_release_cfq_groups(cfqd);
3745 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3747 spin_unlock_irq(q->queue_lock);
3749 cfq_shutdown_timer_wq(cfqd);
3751 spin_lock(&cic_index_lock);
3752 ida_remove(&cic_index_ida, cfqd->cic_index);
3753 spin_unlock(&cic_index_lock);
3755 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3756 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3759 static int cfq_alloc_cic_index(void)
3764 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3767 spin_lock(&cic_index_lock);
3768 error = ida_get_new(&cic_index_ida, &index);
3769 spin_unlock(&cic_index_lock);
3770 if (error && error != -EAGAIN)
3777 static void *cfq_init_queue(struct request_queue *q)
3779 struct cfq_data *cfqd;
3781 struct cfq_group *cfqg;
3782 struct cfq_rb_root *st;
3784 i = cfq_alloc_cic_index();
3788 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3792 cfqd->cic_index = i;
3794 /* Init root service tree */
3795 cfqd->grp_service_tree = CFQ_RB_ROOT;
3797 /* Init root group */
3798 cfqg = &cfqd->root_group;
3799 for_each_cfqg_st(cfqg, i, j, st)
3801 RB_CLEAR_NODE(&cfqg->rb_node);
3803 /* Give preference to root group over other groups */
3804 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3806 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3808 * Take a reference to root group which we never drop. This is just
3809 * to make sure that cfq_put_cfqg() does not try to kfree root group
3811 atomic_set(&cfqg->ref, 1);
3813 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3818 * Not strictly needed (since RB_ROOT just clears the node and we
3819 * zeroed cfqd on alloc), but better be safe in case someone decides
3820 * to add magic to the rb code
3822 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3823 cfqd->prio_trees[i] = RB_ROOT;
3826 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3827 * Grab a permanent reference to it, so that the normal code flow
3828 * will not attempt to free it.
3830 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3831 atomic_inc(&cfqd->oom_cfqq.ref);
3832 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3834 INIT_LIST_HEAD(&cfqd->cic_list);
3838 init_timer(&cfqd->idle_slice_timer);
3839 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3840 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3842 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3844 cfqd->cfq_quantum = cfq_quantum;
3845 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3846 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3847 cfqd->cfq_back_max = cfq_back_max;
3848 cfqd->cfq_back_penalty = cfq_back_penalty;
3849 cfqd->cfq_slice[0] = cfq_slice_async;
3850 cfqd->cfq_slice[1] = cfq_slice_sync;
3851 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3852 cfqd->cfq_slice_idle = cfq_slice_idle;
3853 cfqd->cfq_latency = 1;
3854 cfqd->cfq_group_isolation = 0;
3857 * we optimistically start assuming sync ops weren't delayed in last
3858 * second, in order to have larger depth for async operations.
3860 cfqd->last_delayed_sync = jiffies - HZ;
3864 static void cfq_slab_kill(void)
3867 * Caller already ensured that pending RCU callbacks are completed,
3868 * so we should have no busy allocations at this point.
3871 kmem_cache_destroy(cfq_pool);
3873 kmem_cache_destroy(cfq_ioc_pool);
3876 static int __init cfq_slab_setup(void)
3878 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3882 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3893 * sysfs parts below -->
3896 cfq_var_show(unsigned int var, char *page)
3898 return sprintf(page, "%d\n", var);
3902 cfq_var_store(unsigned int *var, const char *page, size_t count)
3904 char *p = (char *) page;
3906 *var = simple_strtoul(p, &p, 10);
3910 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3911 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3913 struct cfq_data *cfqd = e->elevator_data; \
3914 unsigned int __data = __VAR; \
3916 __data = jiffies_to_msecs(__data); \
3917 return cfq_var_show(__data, (page)); \
3919 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3920 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3921 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3922 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3923 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3924 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3925 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3926 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3927 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
3928 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
3929 SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
3930 #undef SHOW_FUNCTION
3932 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3933 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3935 struct cfq_data *cfqd = e->elevator_data; \
3936 unsigned int __data; \
3937 int ret = cfq_var_store(&__data, (page), count); \
3938 if (__data < (MIN)) \
3940 else if (__data > (MAX)) \
3943 *(__PTR) = msecs_to_jiffies(__data); \
3945 *(__PTR) = __data; \
3948 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
3949 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3951 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3953 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
3954 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3956 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
3957 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3958 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
3959 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3961 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
3962 STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
3963 #undef STORE_FUNCTION
3965 #define CFQ_ATTR(name) \
3966 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3968 static struct elv_fs_entry cfq_attrs[] = {
3970 CFQ_ATTR(fifo_expire_sync),
3971 CFQ_ATTR(fifo_expire_async),
3972 CFQ_ATTR(back_seek_max),
3973 CFQ_ATTR(back_seek_penalty),
3974 CFQ_ATTR(slice_sync),
3975 CFQ_ATTR(slice_async),
3976 CFQ_ATTR(slice_async_rq),
3977 CFQ_ATTR(slice_idle),
3978 CFQ_ATTR(low_latency),
3979 CFQ_ATTR(group_isolation),
3983 static struct elevator_type iosched_cfq = {
3985 .elevator_merge_fn = cfq_merge,
3986 .elevator_merged_fn = cfq_merged_request,
3987 .elevator_merge_req_fn = cfq_merged_requests,
3988 .elevator_allow_merge_fn = cfq_allow_merge,
3989 .elevator_bio_merged_fn = cfq_bio_merged,
3990 .elevator_dispatch_fn = cfq_dispatch_requests,
3991 .elevator_add_req_fn = cfq_insert_request,
3992 .elevator_activate_req_fn = cfq_activate_request,
3993 .elevator_deactivate_req_fn = cfq_deactivate_request,
3994 .elevator_queue_empty_fn = cfq_queue_empty,
3995 .elevator_completed_req_fn = cfq_completed_request,
3996 .elevator_former_req_fn = elv_rb_former_request,
3997 .elevator_latter_req_fn = elv_rb_latter_request,
3998 .elevator_set_req_fn = cfq_set_request,
3999 .elevator_put_req_fn = cfq_put_request,
4000 .elevator_may_queue_fn = cfq_may_queue,
4001 .elevator_init_fn = cfq_init_queue,
4002 .elevator_exit_fn = cfq_exit_queue,
4003 .trim = cfq_free_io_context,
4005 .elevator_attrs = cfq_attrs,
4006 .elevator_name = "cfq",
4007 .elevator_owner = THIS_MODULE,
4010 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4011 static struct blkio_policy_type blkio_policy_cfq = {
4013 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4014 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4016 .plid = BLKIO_POLICY_PROP,
4019 static struct blkio_policy_type blkio_policy_cfq;
4022 static int __init cfq_init(void)
4025 * could be 0 on HZ < 1000 setups
4027 if (!cfq_slice_async)
4028 cfq_slice_async = 1;
4029 if (!cfq_slice_idle)
4032 if (cfq_slab_setup())
4035 elv_register(&iosched_cfq);
4036 blkio_policy_register(&blkio_policy_cfq);
4041 static void __exit cfq_exit(void)
4043 DECLARE_COMPLETION_ONSTACK(all_gone);
4044 blkio_policy_unregister(&blkio_policy_cfq);
4045 elv_unregister(&iosched_cfq);
4046 ioc_gone = &all_gone;
4047 /* ioc_gone's update must be visible before reading ioc_count */
4051 * this also protects us from entering cfq_slab_kill() with
4052 * pending RCU callbacks
4054 if (elv_ioc_count_read(cfq_ioc_count))
4055 wait_for_completion(&all_gone);
4056 ida_destroy(&cic_index_ida);
4060 module_init(cfq_init);
4061 module_exit(cfq_exit);
4063 MODULE_AUTHOR("Jens Axboe");
4064 MODULE_LICENSE("GPL");
4065 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");