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 int cfq_group_idle = HZ / 125;
34 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
35 static const int cfq_hist_divisor = 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 ((struct cfq_io_context *) (rq)->elevator_private[0])
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
61 static struct kmem_cache *cfq_pool;
62 static struct kmem_cache *cfq_ioc_pool;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
65 static struct completion *ioc_gone;
66 static DEFINE_SPINLOCK(ioc_gone_lock);
68 static DEFINE_SPINLOCK(cic_index_lock);
69 static DEFINE_IDA(cic_index_ida);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight;
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 /* number of requests that are on the dispatch list or inside driver */
135 /* io prio of this group */
136 unsigned short ioprio, org_ioprio;
137 unsigned short ioprio_class;
142 sector_t last_request_pos;
144 struct cfq_rb_root *service_tree;
145 struct cfq_queue *new_cfqq;
146 struct cfq_group *cfqg;
147 /* Number of sectors dispatched from queue in single dispatch round */
148 unsigned long nr_sectors;
152 * First index in the service_trees.
153 * IDLE is handled separately, so it has negative index
163 * Second index in the service_trees.
167 SYNC_NOIDLE_WORKLOAD = 1,
171 /* This is per cgroup per device grouping structure */
173 /* group service_tree member */
174 struct rb_node rb_node;
176 /* group service_tree key */
179 unsigned int new_weight;
182 /* number of cfqq currently on this group */
186 * Per group busy queues 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;
211 /* number of requests that are on the dispatch list or inside driver */
216 * Per block device queue structure
219 struct request_queue *queue;
220 /* Root service tree for cfq_groups */
221 struct cfq_rb_root grp_service_tree;
222 struct cfq_group root_group;
225 * The priority currently being served
227 enum wl_prio_t serving_prio;
228 enum wl_type_t serving_type;
229 unsigned long workload_expires;
230 struct cfq_group *serving_group;
233 * Each priority tree is sorted by next_request position. These
234 * trees are used when determining if two or more queues are
235 * interleaving requests (see cfq_close_cooperator).
237 struct rb_root prio_trees[CFQ_PRIO_LISTS];
239 unsigned int busy_queues;
240 unsigned int busy_sync_queues;
246 * queue-depth detection
252 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
253 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
256 int hw_tag_est_depth;
257 unsigned int hw_tag_samples;
260 * idle window management
262 struct timer_list idle_slice_timer;
263 struct work_struct unplug_work;
265 struct cfq_queue *active_queue;
266 struct cfq_io_context *active_cic;
269 * async queue for each priority case
271 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
272 struct cfq_queue *async_idle_cfqq;
274 sector_t last_position;
277 * tunables, see top of file
279 unsigned int cfq_quantum;
280 unsigned int cfq_fifo_expire[2];
281 unsigned int cfq_back_penalty;
282 unsigned int cfq_back_max;
283 unsigned int cfq_slice[2];
284 unsigned int cfq_slice_async_rq;
285 unsigned int cfq_slice_idle;
286 unsigned int cfq_group_idle;
287 unsigned int cfq_latency;
289 unsigned int cic_index;
290 struct list_head cic_list;
293 * Fallback dummy cfqq for extreme OOM conditions
295 struct cfq_queue oom_cfqq;
297 unsigned long last_delayed_sync;
299 /* List of cfq groups being managed on this device*/
300 struct hlist_head cfqg_list;
302 /* Number of groups which are on blkcg->blkg_list */
303 unsigned int nr_blkcg_linked_grps;
306 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
308 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
315 if (prio == IDLE_WORKLOAD)
316 return &cfqg->service_tree_idle;
318 return &cfqg->service_trees[prio][type];
321 enum cfqq_state_flags {
322 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
323 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
324 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
325 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
326 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
327 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
328 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
329 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
330 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
331 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
332 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
333 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
334 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
337 #define CFQ_CFQQ_FNS(name) \
338 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
340 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
342 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
344 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
346 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
348 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
352 CFQ_CFQQ_FNS(wait_request);
353 CFQ_CFQQ_FNS(must_dispatch);
354 CFQ_CFQQ_FNS(must_alloc_slice);
355 CFQ_CFQQ_FNS(fifo_expire);
356 CFQ_CFQQ_FNS(idle_window);
357 CFQ_CFQQ_FNS(prio_changed);
358 CFQ_CFQQ_FNS(slice_new);
361 CFQ_CFQQ_FNS(split_coop);
363 CFQ_CFQQ_FNS(wait_busy);
366 #ifdef CONFIG_CFQ_GROUP_IOSCHED
367 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
368 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
369 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
370 blkg_path(&(cfqq)->cfqg->blkg), ##args)
372 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
373 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
374 blkg_path(&(cfqg)->blkg), ##args) \
377 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
378 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
379 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
381 #define cfq_log(cfqd, fmt, args...) \
382 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
384 /* Traverses through cfq group service trees */
385 #define for_each_cfqg_st(cfqg, i, j, st) \
386 for (i = 0; i <= IDLE_WORKLOAD; i++) \
387 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
388 : &cfqg->service_tree_idle; \
389 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
390 (i == IDLE_WORKLOAD && j == 0); \
391 j++, st = i < IDLE_WORKLOAD ? \
392 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool iops_mode(struct cfq_data *cfqd)
398 * If we are not idling on queues and it is a NCQ drive, parallel
399 * execution of requests is on and measuring time is not possible
400 * in most of the cases until and unless we drive shallower queue
401 * depths and that becomes a performance bottleneck. In such cases
402 * switch to start providing fairness in terms of number of IOs.
404 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
410 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
412 if (cfq_class_idle(cfqq))
413 return IDLE_WORKLOAD;
414 if (cfq_class_rt(cfqq))
420 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
422 if (!cfq_cfqq_sync(cfqq))
423 return ASYNC_WORKLOAD;
424 if (!cfq_cfqq_idle_window(cfqq))
425 return SYNC_NOIDLE_WORKLOAD;
426 return SYNC_WORKLOAD;
429 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
430 struct cfq_data *cfqd,
431 struct cfq_group *cfqg)
433 if (wl == IDLE_WORKLOAD)
434 return cfqg->service_tree_idle.count;
436 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
437 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
438 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
441 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
442 struct cfq_group *cfqg)
444 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
445 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
448 static void cfq_dispatch_insert(struct request_queue *, struct request *);
449 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
450 struct io_context *, gfp_t);
451 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
452 struct io_context *);
454 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
457 return cic->cfqq[is_sync];
460 static inline void cic_set_cfqq(struct cfq_io_context *cic,
461 struct cfq_queue *cfqq, bool is_sync)
463 cic->cfqq[is_sync] = cfqq;
466 #define CIC_DEAD_KEY 1ul
467 #define CIC_DEAD_INDEX_SHIFT 1
469 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
471 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
474 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
476 struct cfq_data *cfqd = cic->key;
478 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
485 * We regard a request as SYNC, if it's either a read or has the SYNC bit
486 * set (in which case it could also be direct WRITE).
488 static inline bool cfq_bio_sync(struct bio *bio)
490 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
494 * scheduler run of queue, if there are requests pending and no one in the
495 * driver that will restart queueing
497 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
499 if (cfqd->busy_queues) {
500 cfq_log(cfqd, "schedule dispatch");
501 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
506 * Scale schedule slice based on io priority. Use the sync time slice only
507 * if a queue is marked sync and has sync io queued. A sync queue with async
508 * io only, should not get full sync slice length.
510 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
513 const int base_slice = cfqd->cfq_slice[sync];
515 WARN_ON(prio >= IOPRIO_BE_NR);
517 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
521 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
523 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
526 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
528 u64 d = delta << CFQ_SERVICE_SHIFT;
530 d = d * BLKIO_WEIGHT_DEFAULT;
531 do_div(d, cfqg->weight);
535 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
537 s64 delta = (s64)(vdisktime - min_vdisktime);
539 min_vdisktime = vdisktime;
541 return min_vdisktime;
544 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
546 s64 delta = (s64)(vdisktime - min_vdisktime);
548 min_vdisktime = vdisktime;
550 return min_vdisktime;
553 static void update_min_vdisktime(struct cfq_rb_root *st)
555 struct cfq_group *cfqg;
558 cfqg = rb_entry_cfqg(st->left);
559 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
565 * get averaged number of queues of RT/BE priority.
566 * average is updated, with a formula that gives more weight to higher numbers,
567 * to quickly follows sudden increases and decrease slowly
570 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
571 struct cfq_group *cfqg, bool rt)
573 unsigned min_q, max_q;
574 unsigned mult = cfq_hist_divisor - 1;
575 unsigned round = cfq_hist_divisor / 2;
576 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
578 min_q = min(cfqg->busy_queues_avg[rt], busy);
579 max_q = max(cfqg->busy_queues_avg[rt], busy);
580 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
582 return cfqg->busy_queues_avg[rt];
585 static inline unsigned
586 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
588 struct cfq_rb_root *st = &cfqd->grp_service_tree;
590 return cfq_target_latency * cfqg->weight / st->total_weight;
593 static inline unsigned
594 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
596 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
597 if (cfqd->cfq_latency) {
599 * interested queues (we consider only the ones with the same
600 * priority class in the cfq group)
602 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
604 unsigned sync_slice = cfqd->cfq_slice[1];
605 unsigned expect_latency = sync_slice * iq;
606 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
608 if (expect_latency > group_slice) {
609 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
610 /* scale low_slice according to IO priority
611 * and sync vs async */
613 min(slice, base_low_slice * slice / sync_slice);
614 /* the adapted slice value is scaled to fit all iqs
615 * into the target latency */
616 slice = max(slice * group_slice / expect_latency,
624 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
626 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
628 cfqq->slice_start = jiffies;
629 cfqq->slice_end = jiffies + slice;
630 cfqq->allocated_slice = slice;
631 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
635 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
636 * isn't valid until the first request from the dispatch is activated
637 * and the slice time set.
639 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
641 if (cfq_cfqq_slice_new(cfqq))
643 if (time_before(jiffies, cfqq->slice_end))
650 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
651 * We choose the request that is closest to the head right now. Distance
652 * behind the head is penalized and only allowed to a certain extent.
654 static struct request *
655 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
657 sector_t s1, s2, d1 = 0, d2 = 0;
658 unsigned long back_max;
659 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
660 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
661 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
663 if (rq1 == NULL || rq1 == rq2)
668 if (rq_is_sync(rq1) != rq_is_sync(rq2))
669 return rq_is_sync(rq1) ? rq1 : rq2;
671 s1 = blk_rq_pos(rq1);
672 s2 = blk_rq_pos(rq2);
675 * by definition, 1KiB is 2 sectors
677 back_max = cfqd->cfq_back_max * 2;
680 * Strict one way elevator _except_ in the case where we allow
681 * short backward seeks which are biased as twice the cost of a
682 * similar forward seek.
686 else if (s1 + back_max >= last)
687 d1 = (last - s1) * cfqd->cfq_back_penalty;
689 wrap |= CFQ_RQ1_WRAP;
693 else if (s2 + back_max >= last)
694 d2 = (last - s2) * cfqd->cfq_back_penalty;
696 wrap |= CFQ_RQ2_WRAP;
698 /* Found required data */
701 * By doing switch() on the bit mask "wrap" we avoid having to
702 * check two variables for all permutations: --> faster!
705 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
721 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
724 * Since both rqs are wrapped,
725 * start with the one that's further behind head
726 * (--> only *one* back seek required),
727 * since back seek takes more time than forward.
737 * The below is leftmost cache rbtree addon
739 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
741 /* Service tree is empty */
746 root->left = rb_first(&root->rb);
749 return rb_entry(root->left, struct cfq_queue, rb_node);
754 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
757 root->left = rb_first(&root->rb);
760 return rb_entry_cfqg(root->left);
765 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
771 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
775 rb_erase_init(n, &root->rb);
780 * would be nice to take fifo expire time into account as well
782 static struct request *
783 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
784 struct request *last)
786 struct rb_node *rbnext = rb_next(&last->rb_node);
787 struct rb_node *rbprev = rb_prev(&last->rb_node);
788 struct request *next = NULL, *prev = NULL;
790 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
793 prev = rb_entry_rq(rbprev);
796 next = rb_entry_rq(rbnext);
798 rbnext = rb_first(&cfqq->sort_list);
799 if (rbnext && rbnext != &last->rb_node)
800 next = rb_entry_rq(rbnext);
803 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
806 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
807 struct cfq_queue *cfqq)
810 * just an approximation, should be ok.
812 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
813 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
817 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
819 return cfqg->vdisktime - st->min_vdisktime;
823 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
825 struct rb_node **node = &st->rb.rb_node;
826 struct rb_node *parent = NULL;
827 struct cfq_group *__cfqg;
828 s64 key = cfqg_key(st, cfqg);
831 while (*node != NULL) {
833 __cfqg = rb_entry_cfqg(parent);
835 if (key < cfqg_key(st, __cfqg))
836 node = &parent->rb_left;
838 node = &parent->rb_right;
844 st->left = &cfqg->rb_node;
846 rb_link_node(&cfqg->rb_node, parent, node);
847 rb_insert_color(&cfqg->rb_node, &st->rb);
851 cfq_update_group_weight(struct cfq_group *cfqg)
853 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
854 if (cfqg->needs_update) {
855 cfqg->weight = cfqg->new_weight;
856 cfqg->needs_update = false;
861 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
863 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
865 cfq_update_group_weight(cfqg);
866 __cfq_group_service_tree_add(st, cfqg);
867 st->total_weight += cfqg->weight;
871 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
873 struct cfq_rb_root *st = &cfqd->grp_service_tree;
874 struct cfq_group *__cfqg;
878 if (!RB_EMPTY_NODE(&cfqg->rb_node))
882 * Currently put the group at the end. Later implement something
883 * so that groups get lesser vtime based on their weights, so that
884 * if group does not loose all if it was not continuously backlogged.
886 n = rb_last(&st->rb);
888 __cfqg = rb_entry_cfqg(n);
889 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
891 cfqg->vdisktime = st->min_vdisktime;
892 cfq_group_service_tree_add(st, cfqg);
896 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
898 st->total_weight -= cfqg->weight;
899 if (!RB_EMPTY_NODE(&cfqg->rb_node))
900 cfq_rb_erase(&cfqg->rb_node, st);
904 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
906 struct cfq_rb_root *st = &cfqd->grp_service_tree;
908 BUG_ON(cfqg->nr_cfqq < 1);
911 /* If there are other cfq queues under this group, don't delete it */
915 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
916 cfq_group_service_tree_del(st, cfqg);
917 cfqg->saved_workload_slice = 0;
918 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
921 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
922 unsigned int *unaccounted_time)
924 unsigned int slice_used;
927 * Queue got expired before even a single request completed or
928 * got expired immediately after first request completion.
930 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
932 * Also charge the seek time incurred to the group, otherwise
933 * if there are mutiple queues in the group, each can dispatch
934 * a single request on seeky media and cause lots of seek time
935 * and group will never know it.
937 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
940 slice_used = jiffies - cfqq->slice_start;
941 if (slice_used > cfqq->allocated_slice) {
942 *unaccounted_time = slice_used - cfqq->allocated_slice;
943 slice_used = cfqq->allocated_slice;
945 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
946 *unaccounted_time += cfqq->slice_start -
947 cfqq->dispatch_start;
953 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
954 struct cfq_queue *cfqq)
956 struct cfq_rb_root *st = &cfqd->grp_service_tree;
957 unsigned int used_sl, charge, unaccounted_sl = 0;
958 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
959 - cfqg->service_tree_idle.count;
962 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
965 charge = cfqq->slice_dispatch;
966 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
967 charge = cfqq->allocated_slice;
969 /* Can't update vdisktime while group is on service tree */
970 cfq_group_service_tree_del(st, cfqg);
971 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
972 /* If a new weight was requested, update now, off tree */
973 cfq_group_service_tree_add(st, cfqg);
975 /* This group is being expired. Save the context */
976 if (time_after(cfqd->workload_expires, jiffies)) {
977 cfqg->saved_workload_slice = cfqd->workload_expires
979 cfqg->saved_workload = cfqd->serving_type;
980 cfqg->saved_serving_prio = cfqd->serving_prio;
982 cfqg->saved_workload_slice = 0;
984 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
986 cfq_log_cfqq(cfqq->cfqd, cfqq,
987 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
988 used_sl, cfqq->slice_dispatch, charge,
989 iops_mode(cfqd), cfqq->nr_sectors);
990 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
992 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
995 #ifdef CONFIG_CFQ_GROUP_IOSCHED
996 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
999 return container_of(blkg, struct cfq_group, blkg);
1003 static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1004 unsigned int weight)
1006 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1007 cfqg->new_weight = weight;
1008 cfqg->needs_update = true;
1011 static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
1012 struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
1014 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1015 unsigned int major, minor;
1018 * Add group onto cgroup list. It might happen that bdi->dev is
1019 * not initialized yet. Initialize this new group without major
1020 * and minor info and this info will be filled in once a new thread
1024 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1025 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1026 (void *)cfqd, MKDEV(major, minor));
1028 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1031 cfqd->nr_blkcg_linked_grps++;
1032 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1034 /* Add group on cfqd list */
1035 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1039 * Should be called from sleepable context. No request queue lock as per
1040 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1041 * from sleepable context.
1043 static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
1045 struct cfq_group *cfqg = NULL;
1047 struct cfq_rb_root *st;
1049 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1053 for_each_cfqg_st(cfqg, i, j, st)
1055 RB_CLEAR_NODE(&cfqg->rb_node);
1058 * Take the initial reference that will be released on destroy
1059 * This can be thought of a joint reference by cgroup and
1060 * elevator which will be dropped by either elevator exit
1061 * or cgroup deletion path depending on who is exiting first.
1065 ret = blkio_alloc_blkg_stats(&cfqg->blkg);
1074 static struct cfq_group *
1075 cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
1077 struct cfq_group *cfqg = NULL;
1079 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1080 unsigned int major, minor;
1083 * This is the common case when there are no blkio cgroups.
1084 * Avoid lookup in this case
1086 if (blkcg == &blkio_root_cgroup)
1087 cfqg = &cfqd->root_group;
1089 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1091 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1092 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1093 cfqg->blkg.dev = MKDEV(major, minor);
1100 * Search for the cfq group current task belongs to. request_queue lock must
1103 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1105 struct blkio_cgroup *blkcg;
1106 struct cfq_group *cfqg = NULL, *__cfqg = NULL;
1107 struct request_queue *q = cfqd->queue;
1110 blkcg = task_blkio_cgroup(current);
1111 cfqg = cfq_find_cfqg(cfqd, blkcg);
1118 * Need to allocate a group. Allocation of group also needs allocation
1119 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1120 * we need to drop rcu lock and queue_lock before we call alloc.
1122 * Not taking any queue reference here and assuming that queue is
1123 * around by the time we return. CFQ queue allocation code does
1124 * the same. It might be racy though.
1128 spin_unlock_irq(q->queue_lock);
1130 cfqg = cfq_alloc_cfqg(cfqd);
1132 spin_lock_irq(q->queue_lock);
1135 blkcg = task_blkio_cgroup(current);
1138 * If some other thread already allocated the group while we were
1139 * not holding queue lock, free up the group
1141 __cfqg = cfq_find_cfqg(cfqd, blkcg);
1150 cfqg = &cfqd->root_group;
1152 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
1157 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1163 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1165 /* Currently, all async queues are mapped to root group */
1166 if (!cfq_cfqq_sync(cfqq))
1167 cfqg = &cfqq->cfqd->root_group;
1170 /* cfqq reference on cfqg */
1174 static void cfq_put_cfqg(struct cfq_group *cfqg)
1176 struct cfq_rb_root *st;
1179 BUG_ON(cfqg->ref <= 0);
1183 for_each_cfqg_st(cfqg, i, j, st)
1184 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1185 free_percpu(cfqg->blkg.stats_cpu);
1189 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1191 /* Something wrong if we are trying to remove same group twice */
1192 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1194 hlist_del_init(&cfqg->cfqd_node);
1197 * Put the reference taken at the time of creation so that when all
1198 * queues are gone, group can be destroyed.
1203 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1205 struct hlist_node *pos, *n;
1206 struct cfq_group *cfqg;
1208 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1210 * If cgroup removal path got to blk_group first and removed
1211 * it from cgroup list, then it will take care of destroying
1214 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1215 cfq_destroy_cfqg(cfqd, cfqg);
1220 * Blk cgroup controller notification saying that blkio_group object is being
1221 * delinked as associated cgroup object is going away. That also means that
1222 * no new IO will come in this group. So get rid of this group as soon as
1223 * any pending IO in the group is finished.
1225 * This function is called under rcu_read_lock(). key is the rcu protected
1226 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1229 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1230 * it should not be NULL as even if elevator was exiting, cgroup deltion
1231 * path got to it first.
1233 static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1235 unsigned long flags;
1236 struct cfq_data *cfqd = key;
1238 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1239 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1240 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1243 #else /* GROUP_IOSCHED */
1244 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1246 return &cfqd->root_group;
1249 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1255 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1259 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1260 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1262 #endif /* GROUP_IOSCHED */
1265 * The cfqd->service_trees holds all pending cfq_queue's that have
1266 * requests waiting to be processed. It is sorted in the order that
1267 * we will service the queues.
1269 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1272 struct rb_node **p, *parent;
1273 struct cfq_queue *__cfqq;
1274 unsigned long rb_key;
1275 struct cfq_rb_root *service_tree;
1279 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1281 if (cfq_class_idle(cfqq)) {
1282 rb_key = CFQ_IDLE_DELAY;
1283 parent = rb_last(&service_tree->rb);
1284 if (parent && parent != &cfqq->rb_node) {
1285 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1286 rb_key += __cfqq->rb_key;
1289 } else if (!add_front) {
1291 * Get our rb key offset. Subtract any residual slice
1292 * value carried from last service. A negative resid
1293 * count indicates slice overrun, and this should position
1294 * the next service time further away in the tree.
1296 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1297 rb_key -= cfqq->slice_resid;
1298 cfqq->slice_resid = 0;
1301 __cfqq = cfq_rb_first(service_tree);
1302 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1305 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1308 * same position, nothing more to do
1310 if (rb_key == cfqq->rb_key &&
1311 cfqq->service_tree == service_tree)
1314 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1315 cfqq->service_tree = NULL;
1320 cfqq->service_tree = service_tree;
1321 p = &service_tree->rb.rb_node;
1326 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1329 * sort by key, that represents service time.
1331 if (time_before(rb_key, __cfqq->rb_key))
1334 n = &(*p)->rb_right;
1342 service_tree->left = &cfqq->rb_node;
1344 cfqq->rb_key = rb_key;
1345 rb_link_node(&cfqq->rb_node, parent, p);
1346 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1347 service_tree->count++;
1348 if (add_front || !new_cfqq)
1350 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1353 static struct cfq_queue *
1354 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1355 sector_t sector, struct rb_node **ret_parent,
1356 struct rb_node ***rb_link)
1358 struct rb_node **p, *parent;
1359 struct cfq_queue *cfqq = NULL;
1367 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1370 * Sort strictly based on sector. Smallest to the left,
1371 * largest to the right.
1373 if (sector > blk_rq_pos(cfqq->next_rq))
1374 n = &(*p)->rb_right;
1375 else if (sector < blk_rq_pos(cfqq->next_rq))
1383 *ret_parent = parent;
1389 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1391 struct rb_node **p, *parent;
1392 struct cfq_queue *__cfqq;
1395 rb_erase(&cfqq->p_node, cfqq->p_root);
1396 cfqq->p_root = NULL;
1399 if (cfq_class_idle(cfqq))
1404 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1405 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1406 blk_rq_pos(cfqq->next_rq), &parent, &p);
1408 rb_link_node(&cfqq->p_node, parent, p);
1409 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1411 cfqq->p_root = NULL;
1415 * Update cfqq's position in the service tree.
1417 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1420 * Resorting requires the cfqq to be on the RR list already.
1422 if (cfq_cfqq_on_rr(cfqq)) {
1423 cfq_service_tree_add(cfqd, cfqq, 0);
1424 cfq_prio_tree_add(cfqd, cfqq);
1429 * add to busy list of queues for service, trying to be fair in ordering
1430 * the pending list according to last request service
1432 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1434 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1435 BUG_ON(cfq_cfqq_on_rr(cfqq));
1436 cfq_mark_cfqq_on_rr(cfqq);
1437 cfqd->busy_queues++;
1438 if (cfq_cfqq_sync(cfqq))
1439 cfqd->busy_sync_queues++;
1441 cfq_resort_rr_list(cfqd, cfqq);
1445 * Called when the cfqq no longer has requests pending, remove it from
1448 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1450 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1451 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1452 cfq_clear_cfqq_on_rr(cfqq);
1454 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1455 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1456 cfqq->service_tree = NULL;
1459 rb_erase(&cfqq->p_node, cfqq->p_root);
1460 cfqq->p_root = NULL;
1463 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1464 BUG_ON(!cfqd->busy_queues);
1465 cfqd->busy_queues--;
1466 if (cfq_cfqq_sync(cfqq))
1467 cfqd->busy_sync_queues--;
1471 * rb tree support functions
1473 static void cfq_del_rq_rb(struct request *rq)
1475 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1476 const int sync = rq_is_sync(rq);
1478 BUG_ON(!cfqq->queued[sync]);
1479 cfqq->queued[sync]--;
1481 elv_rb_del(&cfqq->sort_list, rq);
1483 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1485 * Queue will be deleted from service tree when we actually
1486 * expire it later. Right now just remove it from prio tree
1490 rb_erase(&cfqq->p_node, cfqq->p_root);
1491 cfqq->p_root = NULL;
1496 static void cfq_add_rq_rb(struct request *rq)
1498 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1499 struct cfq_data *cfqd = cfqq->cfqd;
1500 struct request *prev;
1502 cfqq->queued[rq_is_sync(rq)]++;
1504 elv_rb_add(&cfqq->sort_list, rq);
1506 if (!cfq_cfqq_on_rr(cfqq))
1507 cfq_add_cfqq_rr(cfqd, cfqq);
1510 * check if this request is a better next-serve candidate
1512 prev = cfqq->next_rq;
1513 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1516 * adjust priority tree position, if ->next_rq changes
1518 if (prev != cfqq->next_rq)
1519 cfq_prio_tree_add(cfqd, cfqq);
1521 BUG_ON(!cfqq->next_rq);
1524 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1526 elv_rb_del(&cfqq->sort_list, rq);
1527 cfqq->queued[rq_is_sync(rq)]--;
1528 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1529 rq_data_dir(rq), rq_is_sync(rq));
1531 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1532 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1536 static struct request *
1537 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1539 struct task_struct *tsk = current;
1540 struct cfq_io_context *cic;
1541 struct cfq_queue *cfqq;
1543 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1547 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1549 sector_t sector = bio->bi_sector + bio_sectors(bio);
1551 return elv_rb_find(&cfqq->sort_list, sector);
1557 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1559 struct cfq_data *cfqd = q->elevator->elevator_data;
1561 cfqd->rq_in_driver++;
1562 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1563 cfqd->rq_in_driver);
1565 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1568 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1570 struct cfq_data *cfqd = q->elevator->elevator_data;
1572 WARN_ON(!cfqd->rq_in_driver);
1573 cfqd->rq_in_driver--;
1574 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1575 cfqd->rq_in_driver);
1578 static void cfq_remove_request(struct request *rq)
1580 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1582 if (cfqq->next_rq == rq)
1583 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1585 list_del_init(&rq->queuelist);
1588 cfqq->cfqd->rq_queued--;
1589 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1590 rq_data_dir(rq), rq_is_sync(rq));
1593 static int cfq_merge(struct request_queue *q, struct request **req,
1596 struct cfq_data *cfqd = q->elevator->elevator_data;
1597 struct request *__rq;
1599 __rq = cfq_find_rq_fmerge(cfqd, bio);
1600 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1602 return ELEVATOR_FRONT_MERGE;
1605 return ELEVATOR_NO_MERGE;
1608 static void cfq_merged_request(struct request_queue *q, struct request *req,
1611 if (type == ELEVATOR_FRONT_MERGE) {
1612 struct cfq_queue *cfqq = RQ_CFQQ(req);
1614 cfq_reposition_rq_rb(cfqq, req);
1618 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1621 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1622 bio_data_dir(bio), cfq_bio_sync(bio));
1626 cfq_merged_requests(struct request_queue *q, struct request *rq,
1627 struct request *next)
1629 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1631 * reposition in fifo if next is older than rq
1633 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1634 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1635 list_move(&rq->queuelist, &next->queuelist);
1636 rq_set_fifo_time(rq, rq_fifo_time(next));
1639 if (cfqq->next_rq == next)
1641 cfq_remove_request(next);
1642 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1643 rq_data_dir(next), rq_is_sync(next));
1646 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1649 struct cfq_data *cfqd = q->elevator->elevator_data;
1650 struct cfq_io_context *cic;
1651 struct cfq_queue *cfqq;
1654 * Disallow merge of a sync bio into an async request.
1656 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1660 * Lookup the cfqq that this bio will be queued with. Allow
1661 * merge only if rq is queued there.
1663 cic = cfq_cic_lookup(cfqd, current->io_context);
1667 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1668 return cfqq == RQ_CFQQ(rq);
1671 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1673 del_timer(&cfqd->idle_slice_timer);
1674 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1677 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1678 struct cfq_queue *cfqq)
1681 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1682 cfqd->serving_prio, cfqd->serving_type);
1683 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1684 cfqq->slice_start = 0;
1685 cfqq->dispatch_start = jiffies;
1686 cfqq->allocated_slice = 0;
1687 cfqq->slice_end = 0;
1688 cfqq->slice_dispatch = 0;
1689 cfqq->nr_sectors = 0;
1691 cfq_clear_cfqq_wait_request(cfqq);
1692 cfq_clear_cfqq_must_dispatch(cfqq);
1693 cfq_clear_cfqq_must_alloc_slice(cfqq);
1694 cfq_clear_cfqq_fifo_expire(cfqq);
1695 cfq_mark_cfqq_slice_new(cfqq);
1697 cfq_del_timer(cfqd, cfqq);
1700 cfqd->active_queue = cfqq;
1704 * current cfqq expired its slice (or was too idle), select new one
1707 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1710 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1712 if (cfq_cfqq_wait_request(cfqq))
1713 cfq_del_timer(cfqd, cfqq);
1715 cfq_clear_cfqq_wait_request(cfqq);
1716 cfq_clear_cfqq_wait_busy(cfqq);
1719 * If this cfqq is shared between multiple processes, check to
1720 * make sure that those processes are still issuing I/Os within
1721 * the mean seek distance. If not, it may be time to break the
1722 * queues apart again.
1724 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1725 cfq_mark_cfqq_split_coop(cfqq);
1728 * store what was left of this slice, if the queue idled/timed out
1731 if (cfq_cfqq_slice_new(cfqq))
1732 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1734 cfqq->slice_resid = cfqq->slice_end - jiffies;
1735 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1738 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1740 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1741 cfq_del_cfqq_rr(cfqd, cfqq);
1743 cfq_resort_rr_list(cfqd, cfqq);
1745 if (cfqq == cfqd->active_queue)
1746 cfqd->active_queue = NULL;
1748 if (cfqd->active_cic) {
1749 put_io_context(cfqd->active_cic->ioc);
1750 cfqd->active_cic = NULL;
1754 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1756 struct cfq_queue *cfqq = cfqd->active_queue;
1759 __cfq_slice_expired(cfqd, cfqq, timed_out);
1763 * Get next queue for service. Unless we have a queue preemption,
1764 * we'll simply select the first cfqq in the service tree.
1766 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1768 struct cfq_rb_root *service_tree =
1769 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1770 cfqd->serving_type);
1772 if (!cfqd->rq_queued)
1775 /* There is nothing to dispatch */
1778 if (RB_EMPTY_ROOT(&service_tree->rb))
1780 return cfq_rb_first(service_tree);
1783 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1785 struct cfq_group *cfqg;
1786 struct cfq_queue *cfqq;
1788 struct cfq_rb_root *st;
1790 if (!cfqd->rq_queued)
1793 cfqg = cfq_get_next_cfqg(cfqd);
1797 for_each_cfqg_st(cfqg, i, j, st)
1798 if ((cfqq = cfq_rb_first(st)) != NULL)
1804 * Get and set a new active queue for service.
1806 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1807 struct cfq_queue *cfqq)
1810 cfqq = cfq_get_next_queue(cfqd);
1812 __cfq_set_active_queue(cfqd, cfqq);
1816 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1819 if (blk_rq_pos(rq) >= cfqd->last_position)
1820 return blk_rq_pos(rq) - cfqd->last_position;
1822 return cfqd->last_position - blk_rq_pos(rq);
1825 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1828 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1831 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1832 struct cfq_queue *cur_cfqq)
1834 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1835 struct rb_node *parent, *node;
1836 struct cfq_queue *__cfqq;
1837 sector_t sector = cfqd->last_position;
1839 if (RB_EMPTY_ROOT(root))
1843 * First, if we find a request starting at the end of the last
1844 * request, choose it.
1846 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1851 * If the exact sector wasn't found, the parent of the NULL leaf
1852 * will contain the closest sector.
1854 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1855 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1858 if (blk_rq_pos(__cfqq->next_rq) < sector)
1859 node = rb_next(&__cfqq->p_node);
1861 node = rb_prev(&__cfqq->p_node);
1865 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1866 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1874 * cur_cfqq - passed in so that we don't decide that the current queue is
1875 * closely cooperating with itself.
1877 * So, basically we're assuming that that cur_cfqq has dispatched at least
1878 * one request, and that cfqd->last_position reflects a position on the disk
1879 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1882 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1883 struct cfq_queue *cur_cfqq)
1885 struct cfq_queue *cfqq;
1887 if (cfq_class_idle(cur_cfqq))
1889 if (!cfq_cfqq_sync(cur_cfqq))
1891 if (CFQQ_SEEKY(cur_cfqq))
1895 * Don't search priority tree if it's the only queue in the group.
1897 if (cur_cfqq->cfqg->nr_cfqq == 1)
1901 * We should notice if some of the queues are cooperating, eg
1902 * working closely on the same area of the disk. In that case,
1903 * we can group them together and don't waste time idling.
1905 cfqq = cfqq_close(cfqd, cur_cfqq);
1909 /* If new queue belongs to different cfq_group, don't choose it */
1910 if (cur_cfqq->cfqg != cfqq->cfqg)
1914 * It only makes sense to merge sync queues.
1916 if (!cfq_cfqq_sync(cfqq))
1918 if (CFQQ_SEEKY(cfqq))
1922 * Do not merge queues of different priority classes
1924 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1931 * Determine whether we should enforce idle window for this queue.
1934 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1936 enum wl_prio_t prio = cfqq_prio(cfqq);
1937 struct cfq_rb_root *service_tree = cfqq->service_tree;
1939 BUG_ON(!service_tree);
1940 BUG_ON(!service_tree->count);
1942 if (!cfqd->cfq_slice_idle)
1945 /* We never do for idle class queues. */
1946 if (prio == IDLE_WORKLOAD)
1949 /* We do for queues that were marked with idle window flag. */
1950 if (cfq_cfqq_idle_window(cfqq) &&
1951 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1955 * Otherwise, we do only if they are the last ones
1956 * in their service tree.
1958 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1960 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1961 service_tree->count);
1965 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1967 struct cfq_queue *cfqq = cfqd->active_queue;
1968 struct cfq_io_context *cic;
1969 unsigned long sl, group_idle = 0;
1972 * SSD device without seek penalty, disable idling. But only do so
1973 * for devices that support queuing, otherwise we still have a problem
1974 * with sync vs async workloads.
1976 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1979 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1980 WARN_ON(cfq_cfqq_slice_new(cfqq));
1983 * idle is disabled, either manually or by past process history
1985 if (!cfq_should_idle(cfqd, cfqq)) {
1986 /* no queue idling. Check for group idling */
1987 if (cfqd->cfq_group_idle)
1988 group_idle = cfqd->cfq_group_idle;
1994 * still active requests from this queue, don't idle
1996 if (cfqq->dispatched)
2000 * task has exited, don't wait
2002 cic = cfqd->active_cic;
2003 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
2007 * If our average think time is larger than the remaining time
2008 * slice, then don't idle. This avoids overrunning the allotted
2011 if (sample_valid(cic->ttime.ttime_samples) &&
2012 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2013 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2014 cic->ttime.ttime_mean);
2018 /* There are other queues in the group, don't do group idle */
2019 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2022 cfq_mark_cfqq_wait_request(cfqq);
2025 sl = cfqd->cfq_group_idle;
2027 sl = cfqd->cfq_slice_idle;
2029 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2030 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
2031 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2032 group_idle ? 1 : 0);
2036 * Move request from internal lists to the request queue dispatch list.
2038 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2040 struct cfq_data *cfqd = q->elevator->elevator_data;
2041 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2043 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2045 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2046 cfq_remove_request(rq);
2048 (RQ_CFQG(rq))->dispatched++;
2049 elv_dispatch_sort(q, rq);
2051 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2052 cfqq->nr_sectors += blk_rq_sectors(rq);
2053 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2054 rq_data_dir(rq), rq_is_sync(rq));
2058 * return expired entry, or NULL to just start from scratch in rbtree
2060 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2062 struct request *rq = NULL;
2064 if (cfq_cfqq_fifo_expire(cfqq))
2067 cfq_mark_cfqq_fifo_expire(cfqq);
2069 if (list_empty(&cfqq->fifo))
2072 rq = rq_entry_fifo(cfqq->fifo.next);
2073 if (time_before(jiffies, rq_fifo_time(rq)))
2076 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2081 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2083 const int base_rq = cfqd->cfq_slice_async_rq;
2085 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2087 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2091 * Must be called with the queue_lock held.
2093 static int cfqq_process_refs(struct cfq_queue *cfqq)
2095 int process_refs, io_refs;
2097 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2098 process_refs = cfqq->ref - io_refs;
2099 BUG_ON(process_refs < 0);
2100 return process_refs;
2103 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2105 int process_refs, new_process_refs;
2106 struct cfq_queue *__cfqq;
2109 * If there are no process references on the new_cfqq, then it is
2110 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2111 * chain may have dropped their last reference (not just their
2112 * last process reference).
2114 if (!cfqq_process_refs(new_cfqq))
2117 /* Avoid a circular list and skip interim queue merges */
2118 while ((__cfqq = new_cfqq->new_cfqq)) {
2124 process_refs = cfqq_process_refs(cfqq);
2125 new_process_refs = cfqq_process_refs(new_cfqq);
2127 * If the process for the cfqq has gone away, there is no
2128 * sense in merging the queues.
2130 if (process_refs == 0 || new_process_refs == 0)
2134 * Merge in the direction of the lesser amount of work.
2136 if (new_process_refs >= process_refs) {
2137 cfqq->new_cfqq = new_cfqq;
2138 new_cfqq->ref += process_refs;
2140 new_cfqq->new_cfqq = cfqq;
2141 cfqq->ref += new_process_refs;
2145 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2146 struct cfq_group *cfqg, enum wl_prio_t prio)
2148 struct cfq_queue *queue;
2150 bool key_valid = false;
2151 unsigned long lowest_key = 0;
2152 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2154 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2155 /* select the one with lowest rb_key */
2156 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2158 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2159 lowest_key = queue->rb_key;
2168 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2172 struct cfq_rb_root *st;
2173 unsigned group_slice;
2174 enum wl_prio_t original_prio = cfqd->serving_prio;
2176 /* Choose next priority. RT > BE > IDLE */
2177 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2178 cfqd->serving_prio = RT_WORKLOAD;
2179 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2180 cfqd->serving_prio = BE_WORKLOAD;
2182 cfqd->serving_prio = IDLE_WORKLOAD;
2183 cfqd->workload_expires = jiffies + 1;
2187 if (original_prio != cfqd->serving_prio)
2191 * For RT and BE, we have to choose also the type
2192 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2195 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2199 * check workload expiration, and that we still have other queues ready
2201 if (count && !time_after(jiffies, cfqd->workload_expires))
2205 /* otherwise select new workload type */
2206 cfqd->serving_type =
2207 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2208 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2212 * the workload slice is computed as a fraction of target latency
2213 * proportional to the number of queues in that workload, over
2214 * all the queues in the same priority class
2216 group_slice = cfq_group_slice(cfqd, cfqg);
2218 slice = group_slice * count /
2219 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2220 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2222 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2226 * Async queues are currently system wide. Just taking
2227 * proportion of queues with-in same group will lead to higher
2228 * async ratio system wide as generally root group is going
2229 * to have higher weight. A more accurate thing would be to
2230 * calculate system wide asnc/sync ratio.
2232 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2233 tmp = tmp/cfqd->busy_queues;
2234 slice = min_t(unsigned, slice, tmp);
2236 /* async workload slice is scaled down according to
2237 * the sync/async slice ratio. */
2238 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2240 /* sync workload slice is at least 2 * cfq_slice_idle */
2241 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2243 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2244 cfq_log(cfqd, "workload slice:%d", slice);
2245 cfqd->workload_expires = jiffies + slice;
2248 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2250 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2251 struct cfq_group *cfqg;
2253 if (RB_EMPTY_ROOT(&st->rb))
2255 cfqg = cfq_rb_first_group(st);
2256 update_min_vdisktime(st);
2260 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2262 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2264 cfqd->serving_group = cfqg;
2266 /* Restore the workload type data */
2267 if (cfqg->saved_workload_slice) {
2268 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2269 cfqd->serving_type = cfqg->saved_workload;
2270 cfqd->serving_prio = cfqg->saved_serving_prio;
2272 cfqd->workload_expires = jiffies - 1;
2274 choose_service_tree(cfqd, cfqg);
2278 * Select a queue for service. If we have a current active queue,
2279 * check whether to continue servicing it, or retrieve and set a new one.
2281 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2283 struct cfq_queue *cfqq, *new_cfqq = NULL;
2285 cfqq = cfqd->active_queue;
2289 if (!cfqd->rq_queued)
2293 * We were waiting for group to get backlogged. Expire the queue
2295 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2299 * The active queue has run out of time, expire it and select new.
2301 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2303 * If slice had not expired at the completion of last request
2304 * we might not have turned on wait_busy flag. Don't expire
2305 * the queue yet. Allow the group to get backlogged.
2307 * The very fact that we have used the slice, that means we
2308 * have been idling all along on this queue and it should be
2309 * ok to wait for this request to complete.
2311 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2312 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2316 goto check_group_idle;
2320 * The active queue has requests and isn't expired, allow it to
2323 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2327 * If another queue has a request waiting within our mean seek
2328 * distance, let it run. The expire code will check for close
2329 * cooperators and put the close queue at the front of the service
2330 * tree. If possible, merge the expiring queue with the new cfqq.
2332 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2334 if (!cfqq->new_cfqq)
2335 cfq_setup_merge(cfqq, new_cfqq);
2340 * No requests pending. If the active queue still has requests in
2341 * flight or is idling for a new request, allow either of these
2342 * conditions to happen (or time out) before selecting a new queue.
2344 if (timer_pending(&cfqd->idle_slice_timer)) {
2350 * This is a deep seek queue, but the device is much faster than
2351 * the queue can deliver, don't idle
2353 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2354 (cfq_cfqq_slice_new(cfqq) ||
2355 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2356 cfq_clear_cfqq_deep(cfqq);
2357 cfq_clear_cfqq_idle_window(cfqq);
2360 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2366 * If group idle is enabled and there are requests dispatched from
2367 * this group, wait for requests to complete.
2370 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2371 && cfqq->cfqg->dispatched) {
2377 cfq_slice_expired(cfqd, 0);
2380 * Current queue expired. Check if we have to switch to a new
2384 cfq_choose_cfqg(cfqd);
2386 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2391 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2395 while (cfqq->next_rq) {
2396 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2400 BUG_ON(!list_empty(&cfqq->fifo));
2402 /* By default cfqq is not expired if it is empty. Do it explicitly */
2403 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2408 * Drain our current requests. Used for barriers and when switching
2409 * io schedulers on-the-fly.
2411 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2413 struct cfq_queue *cfqq;
2416 /* Expire the timeslice of the current active queue first */
2417 cfq_slice_expired(cfqd, 0);
2418 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2419 __cfq_set_active_queue(cfqd, cfqq);
2420 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2423 BUG_ON(cfqd->busy_queues);
2425 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2429 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2430 struct cfq_queue *cfqq)
2432 /* the queue hasn't finished any request, can't estimate */
2433 if (cfq_cfqq_slice_new(cfqq))
2435 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2442 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2444 unsigned int max_dispatch;
2447 * Drain async requests before we start sync IO
2449 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2453 * If this is an async queue and we have sync IO in flight, let it wait
2455 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2458 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2459 if (cfq_class_idle(cfqq))
2463 * Does this cfqq already have too much IO in flight?
2465 if (cfqq->dispatched >= max_dispatch) {
2466 bool promote_sync = false;
2468 * idle queue must always only have a single IO in flight
2470 if (cfq_class_idle(cfqq))
2474 * If there is only one sync queue
2475 * we can ignore async queue here and give the sync
2476 * queue no dispatch limit. The reason is a sync queue can
2477 * preempt async queue, limiting the sync queue doesn't make
2478 * sense. This is useful for aiostress test.
2480 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2481 promote_sync = true;
2484 * We have other queues, don't allow more IO from this one
2486 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2491 * Sole queue user, no limit
2493 if (cfqd->busy_queues == 1 || promote_sync)
2497 * Normally we start throttling cfqq when cfq_quantum/2
2498 * requests have been dispatched. But we can drive
2499 * deeper queue depths at the beginning of slice
2500 * subjected to upper limit of cfq_quantum.
2502 max_dispatch = cfqd->cfq_quantum;
2506 * Async queues must wait a bit before being allowed dispatch.
2507 * We also ramp up the dispatch depth gradually for async IO,
2508 * based on the last sync IO we serviced
2510 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2511 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2514 depth = last_sync / cfqd->cfq_slice[1];
2515 if (!depth && !cfqq->dispatched)
2517 if (depth < max_dispatch)
2518 max_dispatch = depth;
2522 * If we're below the current max, allow a dispatch
2524 return cfqq->dispatched < max_dispatch;
2528 * Dispatch a request from cfqq, moving them to the request queue
2531 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2535 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2537 if (!cfq_may_dispatch(cfqd, cfqq))
2541 * follow expired path, else get first next available
2543 rq = cfq_check_fifo(cfqq);
2548 * insert request into driver dispatch list
2550 cfq_dispatch_insert(cfqd->queue, rq);
2552 if (!cfqd->active_cic) {
2553 struct cfq_io_context *cic = RQ_CIC(rq);
2555 atomic_long_inc(&cic->ioc->refcount);
2556 cfqd->active_cic = cic;
2563 * Find the cfqq that we need to service and move a request from that to the
2566 static int cfq_dispatch_requests(struct request_queue *q, int force)
2568 struct cfq_data *cfqd = q->elevator->elevator_data;
2569 struct cfq_queue *cfqq;
2571 if (!cfqd->busy_queues)
2574 if (unlikely(force))
2575 return cfq_forced_dispatch(cfqd);
2577 cfqq = cfq_select_queue(cfqd);
2582 * Dispatch a request from this cfqq, if it is allowed
2584 if (!cfq_dispatch_request(cfqd, cfqq))
2587 cfqq->slice_dispatch++;
2588 cfq_clear_cfqq_must_dispatch(cfqq);
2591 * expire an async queue immediately if it has used up its slice. idle
2592 * queue always expire after 1 dispatch round.
2594 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2595 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2596 cfq_class_idle(cfqq))) {
2597 cfqq->slice_end = jiffies + 1;
2598 cfq_slice_expired(cfqd, 0);
2601 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2606 * task holds one reference to the queue, dropped when task exits. each rq
2607 * in-flight on this queue also holds a reference, dropped when rq is freed.
2609 * Each cfq queue took a reference on the parent group. Drop it now.
2610 * queue lock must be held here.
2612 static void cfq_put_queue(struct cfq_queue *cfqq)
2614 struct cfq_data *cfqd = cfqq->cfqd;
2615 struct cfq_group *cfqg;
2617 BUG_ON(cfqq->ref <= 0);
2623 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2624 BUG_ON(rb_first(&cfqq->sort_list));
2625 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2628 if (unlikely(cfqd->active_queue == cfqq)) {
2629 __cfq_slice_expired(cfqd, cfqq, 0);
2630 cfq_schedule_dispatch(cfqd);
2633 BUG_ON(cfq_cfqq_on_rr(cfqq));
2634 kmem_cache_free(cfq_pool, cfqq);
2639 * Call func for each cic attached to this ioc.
2642 call_for_each_cic(struct io_context *ioc,
2643 void (*func)(struct io_context *, struct cfq_io_context *))
2645 struct cfq_io_context *cic;
2646 struct hlist_node *n;
2650 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2656 static void cfq_cic_free_rcu(struct rcu_head *head)
2658 struct cfq_io_context *cic;
2660 cic = container_of(head, struct cfq_io_context, rcu_head);
2662 kmem_cache_free(cfq_ioc_pool, cic);
2663 elv_ioc_count_dec(cfq_ioc_count);
2667 * CFQ scheduler is exiting, grab exit lock and check
2668 * the pending io context count. If it hits zero,
2669 * complete ioc_gone and set it back to NULL
2671 spin_lock(&ioc_gone_lock);
2672 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2676 spin_unlock(&ioc_gone_lock);
2680 static void cfq_cic_free(struct cfq_io_context *cic)
2682 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2685 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2687 unsigned long flags;
2688 unsigned long dead_key = (unsigned long) cic->key;
2690 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2692 spin_lock_irqsave(&ioc->lock, flags);
2693 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2694 hlist_del_rcu(&cic->cic_list);
2695 spin_unlock_irqrestore(&ioc->lock, flags);
2701 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2702 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2703 * and ->trim() which is called with the task lock held
2705 static void cfq_free_io_context(struct io_context *ioc)
2708 * ioc->refcount is zero here, or we are called from elv_unregister(),
2709 * so no more cic's are allowed to be linked into this ioc. So it
2710 * should be ok to iterate over the known list, we will see all cic's
2711 * since no new ones are added.
2713 call_for_each_cic(ioc, cic_free_func);
2716 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2718 struct cfq_queue *__cfqq, *next;
2721 * If this queue was scheduled to merge with another queue, be
2722 * sure to drop the reference taken on that queue (and others in
2723 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2725 __cfqq = cfqq->new_cfqq;
2727 if (__cfqq == cfqq) {
2728 WARN(1, "cfqq->new_cfqq loop detected\n");
2731 next = __cfqq->new_cfqq;
2732 cfq_put_queue(__cfqq);
2737 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2739 if (unlikely(cfqq == cfqd->active_queue)) {
2740 __cfq_slice_expired(cfqd, cfqq, 0);
2741 cfq_schedule_dispatch(cfqd);
2744 cfq_put_cooperator(cfqq);
2746 cfq_put_queue(cfqq);
2749 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2750 struct cfq_io_context *cic)
2752 struct io_context *ioc = cic->ioc;
2754 list_del_init(&cic->queue_list);
2757 * Make sure dead mark is seen for dead queues
2760 cic->key = cfqd_dead_key(cfqd);
2763 if (rcu_dereference(ioc->ioc_data) == cic) {
2765 spin_lock(&ioc->lock);
2766 rcu_assign_pointer(ioc->ioc_data, NULL);
2767 spin_unlock(&ioc->lock);
2771 if (cic->cfqq[BLK_RW_ASYNC]) {
2772 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2773 cic->cfqq[BLK_RW_ASYNC] = NULL;
2776 if (cic->cfqq[BLK_RW_SYNC]) {
2777 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2778 cic->cfqq[BLK_RW_SYNC] = NULL;
2782 static void cfq_exit_single_io_context(struct io_context *ioc,
2783 struct cfq_io_context *cic)
2785 struct cfq_data *cfqd = cic_to_cfqd(cic);
2788 struct request_queue *q = cfqd->queue;
2789 unsigned long flags;
2791 spin_lock_irqsave(q->queue_lock, flags);
2794 * Ensure we get a fresh copy of the ->key to prevent
2795 * race between exiting task and queue
2797 smp_read_barrier_depends();
2798 if (cic->key == cfqd)
2799 __cfq_exit_single_io_context(cfqd, cic);
2801 spin_unlock_irqrestore(q->queue_lock, flags);
2806 * The process that ioc belongs to has exited, we need to clean up
2807 * and put the internal structures we have that belongs to that process.
2809 static void cfq_exit_io_context(struct io_context *ioc)
2811 call_for_each_cic(ioc, cfq_exit_single_io_context);
2814 static struct cfq_io_context *
2815 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2817 struct cfq_io_context *cic;
2819 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2822 cic->ttime.last_end_request = jiffies;
2823 INIT_LIST_HEAD(&cic->queue_list);
2824 INIT_HLIST_NODE(&cic->cic_list);
2825 cic->dtor = cfq_free_io_context;
2826 cic->exit = cfq_exit_io_context;
2827 elv_ioc_count_inc(cfq_ioc_count);
2833 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2835 struct task_struct *tsk = current;
2838 if (!cfq_cfqq_prio_changed(cfqq))
2841 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2842 switch (ioprio_class) {
2844 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2845 case IOPRIO_CLASS_NONE:
2847 * no prio set, inherit CPU scheduling settings
2849 cfqq->ioprio = task_nice_ioprio(tsk);
2850 cfqq->ioprio_class = task_nice_ioclass(tsk);
2852 case IOPRIO_CLASS_RT:
2853 cfqq->ioprio = task_ioprio(ioc);
2854 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2856 case IOPRIO_CLASS_BE:
2857 cfqq->ioprio = task_ioprio(ioc);
2858 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2860 case IOPRIO_CLASS_IDLE:
2861 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2863 cfq_clear_cfqq_idle_window(cfqq);
2868 * keep track of original prio settings in case we have to temporarily
2869 * elevate the priority of this queue
2871 cfqq->org_ioprio = cfqq->ioprio;
2872 cfq_clear_cfqq_prio_changed(cfqq);
2875 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2877 struct cfq_data *cfqd = cic_to_cfqd(cic);
2878 struct cfq_queue *cfqq;
2879 unsigned long flags;
2881 if (unlikely(!cfqd))
2884 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2886 cfqq = cic->cfqq[BLK_RW_ASYNC];
2888 struct cfq_queue *new_cfqq;
2889 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2892 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2893 cfq_put_queue(cfqq);
2897 cfqq = cic->cfqq[BLK_RW_SYNC];
2899 cfq_mark_cfqq_prio_changed(cfqq);
2901 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2904 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2906 call_for_each_cic(ioc, changed_ioprio);
2907 ioc->ioprio_changed = 0;
2910 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2911 pid_t pid, bool is_sync)
2913 RB_CLEAR_NODE(&cfqq->rb_node);
2914 RB_CLEAR_NODE(&cfqq->p_node);
2915 INIT_LIST_HEAD(&cfqq->fifo);
2920 cfq_mark_cfqq_prio_changed(cfqq);
2923 if (!cfq_class_idle(cfqq))
2924 cfq_mark_cfqq_idle_window(cfqq);
2925 cfq_mark_cfqq_sync(cfqq);
2930 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2931 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2933 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2934 struct cfq_data *cfqd = cic_to_cfqd(cic);
2935 unsigned long flags;
2936 struct request_queue *q;
2938 if (unlikely(!cfqd))
2943 spin_lock_irqsave(q->queue_lock, flags);
2947 * Drop reference to sync queue. A new sync queue will be
2948 * assigned in new group upon arrival of a fresh request.
2950 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2951 cic_set_cfqq(cic, NULL, 1);
2952 cfq_put_queue(sync_cfqq);
2955 spin_unlock_irqrestore(q->queue_lock, flags);
2958 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2960 call_for_each_cic(ioc, changed_cgroup);
2961 ioc->cgroup_changed = 0;
2963 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2965 static struct cfq_queue *
2966 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2967 struct io_context *ioc, gfp_t gfp_mask)
2969 struct cfq_queue *cfqq, *new_cfqq = NULL;
2970 struct cfq_io_context *cic;
2971 struct cfq_group *cfqg;
2974 cfqg = cfq_get_cfqg(cfqd);
2975 cic = cfq_cic_lookup(cfqd, ioc);
2976 /* cic always exists here */
2977 cfqq = cic_to_cfqq(cic, is_sync);
2980 * Always try a new alloc if we fell back to the OOM cfqq
2981 * originally, since it should just be a temporary situation.
2983 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2988 } else if (gfp_mask & __GFP_WAIT) {
2989 spin_unlock_irq(cfqd->queue->queue_lock);
2990 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2991 gfp_mask | __GFP_ZERO,
2993 spin_lock_irq(cfqd->queue->queue_lock);
2997 cfqq = kmem_cache_alloc_node(cfq_pool,
2998 gfp_mask | __GFP_ZERO,
3003 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3004 cfq_init_prio_data(cfqq, ioc);
3005 cfq_link_cfqq_cfqg(cfqq, cfqg);
3006 cfq_log_cfqq(cfqd, cfqq, "alloced");
3008 cfqq = &cfqd->oom_cfqq;
3012 kmem_cache_free(cfq_pool, new_cfqq);
3017 static struct cfq_queue **
3018 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3020 switch (ioprio_class) {
3021 case IOPRIO_CLASS_RT:
3022 return &cfqd->async_cfqq[0][ioprio];
3023 case IOPRIO_CLASS_BE:
3024 return &cfqd->async_cfqq[1][ioprio];
3025 case IOPRIO_CLASS_IDLE:
3026 return &cfqd->async_idle_cfqq;
3032 static struct cfq_queue *
3033 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
3036 const int ioprio = task_ioprio(ioc);
3037 const int ioprio_class = task_ioprio_class(ioc);
3038 struct cfq_queue **async_cfqq = NULL;
3039 struct cfq_queue *cfqq = NULL;
3042 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3047 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
3050 * pin the queue now that it's allocated, scheduler exit will prune it
3052 if (!is_sync && !(*async_cfqq)) {
3062 * We drop cfq io contexts lazily, so we may find a dead one.
3065 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3066 struct cfq_io_context *cic)
3068 unsigned long flags;
3070 WARN_ON(!list_empty(&cic->queue_list));
3071 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3073 spin_lock_irqsave(&ioc->lock, flags);
3075 BUG_ON(rcu_dereference_check(ioc->ioc_data,
3076 lockdep_is_held(&ioc->lock)) == cic);
3078 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3079 hlist_del_rcu(&cic->cic_list);
3080 spin_unlock_irqrestore(&ioc->lock, flags);
3085 static struct cfq_io_context *
3086 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3088 struct cfq_io_context *cic;
3089 unsigned long flags;
3097 * we maintain a last-hit cache, to avoid browsing over the tree
3099 cic = rcu_dereference(ioc->ioc_data);
3100 if (cic && cic->key == cfqd) {
3106 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3110 if (unlikely(cic->key != cfqd)) {
3111 cfq_drop_dead_cic(cfqd, ioc, cic);
3116 spin_lock_irqsave(&ioc->lock, flags);
3117 rcu_assign_pointer(ioc->ioc_data, cic);
3118 spin_unlock_irqrestore(&ioc->lock, flags);
3126 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3127 * the process specific cfq io context when entered from the block layer.
3128 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3130 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3131 struct cfq_io_context *cic, gfp_t gfp_mask)
3133 unsigned long flags;
3136 ret = radix_tree_preload(gfp_mask);
3141 spin_lock_irqsave(&ioc->lock, flags);
3142 ret = radix_tree_insert(&ioc->radix_root,
3143 cfqd->cic_index, cic);
3145 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3146 spin_unlock_irqrestore(&ioc->lock, flags);
3148 radix_tree_preload_end();
3151 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3152 list_add(&cic->queue_list, &cfqd->cic_list);
3153 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3158 printk(KERN_ERR "cfq: cic link failed!\n");
3164 * Setup general io context and cfq io context. There can be several cfq
3165 * io contexts per general io context, if this process is doing io to more
3166 * than one device managed by cfq.
3168 static struct cfq_io_context *
3169 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3171 struct io_context *ioc = NULL;
3172 struct cfq_io_context *cic;
3174 might_sleep_if(gfp_mask & __GFP_WAIT);
3176 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3180 cic = cfq_cic_lookup(cfqd, ioc);
3184 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3188 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3192 smp_read_barrier_depends();
3193 if (unlikely(ioc->ioprio_changed))
3194 cfq_ioc_set_ioprio(ioc);
3196 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3197 if (unlikely(ioc->cgroup_changed))
3198 cfq_ioc_set_cgroup(ioc);
3204 put_io_context(ioc);
3209 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3211 unsigned long elapsed = jiffies - ttime->last_end_request;
3212 elapsed = min(elapsed, 2UL * slice_idle);
3214 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3215 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3216 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3220 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3221 struct cfq_io_context *cic)
3223 if (cfq_cfqq_sync(cfqq))
3224 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3228 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3232 sector_t n_sec = blk_rq_sectors(rq);
3233 if (cfqq->last_request_pos) {
3234 if (cfqq->last_request_pos < blk_rq_pos(rq))
3235 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3237 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3240 cfqq->seek_history <<= 1;
3241 if (blk_queue_nonrot(cfqd->queue))
3242 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3244 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3248 * Disable idle window if the process thinks too long or seeks so much that
3252 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3253 struct cfq_io_context *cic)
3255 int old_idle, enable_idle;
3258 * Don't idle for async or idle io prio class
3260 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3263 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3265 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3266 cfq_mark_cfqq_deep(cfqq);
3268 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3270 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3271 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3273 else if (sample_valid(cic->ttime.ttime_samples)) {
3274 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3280 if (old_idle != enable_idle) {
3281 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3283 cfq_mark_cfqq_idle_window(cfqq);
3285 cfq_clear_cfqq_idle_window(cfqq);
3290 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3291 * no or if we aren't sure, a 1 will cause a preempt.
3294 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3297 struct cfq_queue *cfqq;
3299 cfqq = cfqd->active_queue;
3303 if (cfq_class_idle(new_cfqq))
3306 if (cfq_class_idle(cfqq))
3310 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3312 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3316 * if the new request is sync, but the currently running queue is
3317 * not, let the sync request have priority.
3319 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3322 if (new_cfqq->cfqg != cfqq->cfqg)
3325 if (cfq_slice_used(cfqq))
3328 /* Allow preemption only if we are idling on sync-noidle tree */
3329 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3330 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3331 new_cfqq->service_tree->count == 2 &&
3332 RB_EMPTY_ROOT(&cfqq->sort_list))
3336 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3338 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3341 /* An idle queue should not be idle now for some reason */
3342 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3345 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3349 * if this request is as-good as one we would expect from the
3350 * current cfqq, let it preempt
3352 if (cfq_rq_close(cfqd, cfqq, rq))
3359 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3360 * let it have half of its nominal slice.
3362 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3364 struct cfq_queue *old_cfqq = cfqd->active_queue;
3366 cfq_log_cfqq(cfqd, cfqq, "preempt");
3367 cfq_slice_expired(cfqd, 1);
3370 * workload type is changed, don't save slice, otherwise preempt
3373 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3374 cfqq->cfqg->saved_workload_slice = 0;
3377 * Put the new queue at the front of the of the current list,
3378 * so we know that it will be selected next.
3380 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3382 cfq_service_tree_add(cfqd, cfqq, 1);
3384 cfqq->slice_end = 0;
3385 cfq_mark_cfqq_slice_new(cfqq);
3389 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3390 * something we should do about it
3393 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3396 struct cfq_io_context *cic = RQ_CIC(rq);
3400 cfq_update_io_thinktime(cfqd, cfqq, cic);
3401 cfq_update_io_seektime(cfqd, cfqq, rq);
3402 cfq_update_idle_window(cfqd, cfqq, cic);
3404 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3406 if (cfqq == cfqd->active_queue) {
3408 * Remember that we saw a request from this process, but
3409 * don't start queuing just yet. Otherwise we risk seeing lots
3410 * of tiny requests, because we disrupt the normal plugging
3411 * and merging. If the request is already larger than a single
3412 * page, let it rip immediately. For that case we assume that
3413 * merging is already done. Ditto for a busy system that
3414 * has other work pending, don't risk delaying until the
3415 * idle timer unplug to continue working.
3417 if (cfq_cfqq_wait_request(cfqq)) {
3418 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3419 cfqd->busy_queues > 1) {
3420 cfq_del_timer(cfqd, cfqq);
3421 cfq_clear_cfqq_wait_request(cfqq);
3422 __blk_run_queue(cfqd->queue);
3424 cfq_blkiocg_update_idle_time_stats(
3426 cfq_mark_cfqq_must_dispatch(cfqq);
3429 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3431 * not the active queue - expire current slice if it is
3432 * idle and has expired it's mean thinktime or this new queue
3433 * has some old slice time left and is of higher priority or
3434 * this new queue is RT and the current one is BE
3436 cfq_preempt_queue(cfqd, cfqq);
3437 __blk_run_queue(cfqd->queue);
3441 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3443 struct cfq_data *cfqd = q->elevator->elevator_data;
3444 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3446 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3447 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3449 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3450 list_add_tail(&rq->queuelist, &cfqq->fifo);
3452 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3453 &cfqd->serving_group->blkg, rq_data_dir(rq),
3455 cfq_rq_enqueued(cfqd, cfqq, rq);
3459 * Update hw_tag based on peak queue depth over 50 samples under
3462 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3464 struct cfq_queue *cfqq = cfqd->active_queue;
3466 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3467 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3469 if (cfqd->hw_tag == 1)
3472 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3473 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3477 * If active queue hasn't enough requests and can idle, cfq might not
3478 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3481 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3482 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3483 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3486 if (cfqd->hw_tag_samples++ < 50)
3489 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3495 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3497 struct cfq_io_context *cic = cfqd->active_cic;
3499 /* If the queue already has requests, don't wait */
3500 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3503 /* If there are other queues in the group, don't wait */
3504 if (cfqq->cfqg->nr_cfqq > 1)
3507 if (cfq_slice_used(cfqq))
3510 /* if slice left is less than think time, wait busy */
3511 if (cic && sample_valid(cic->ttime.ttime_samples)
3512 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3516 * If think times is less than a jiffy than ttime_mean=0 and above
3517 * will not be true. It might happen that slice has not expired yet
3518 * but will expire soon (4-5 ns) during select_queue(). To cover the
3519 * case where think time is less than a jiffy, mark the queue wait
3520 * busy if only 1 jiffy is left in the slice.
3522 if (cfqq->slice_end - jiffies == 1)
3528 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3530 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3531 struct cfq_data *cfqd = cfqq->cfqd;
3532 const int sync = rq_is_sync(rq);
3536 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3537 !!(rq->cmd_flags & REQ_NOIDLE));
3539 cfq_update_hw_tag(cfqd);
3541 WARN_ON(!cfqd->rq_in_driver);
3542 WARN_ON(!cfqq->dispatched);
3543 cfqd->rq_in_driver--;
3545 (RQ_CFQG(rq))->dispatched--;
3546 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3547 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3548 rq_data_dir(rq), rq_is_sync(rq));
3550 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3553 RQ_CIC(rq)->ttime.last_end_request = now;
3554 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3555 cfqd->last_delayed_sync = now;
3559 * If this is the active queue, check if it needs to be expired,
3560 * or if we want to idle in case it has no pending requests.
3562 if (cfqd->active_queue == cfqq) {
3563 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3565 if (cfq_cfqq_slice_new(cfqq)) {
3566 cfq_set_prio_slice(cfqd, cfqq);
3567 cfq_clear_cfqq_slice_new(cfqq);
3571 * Should we wait for next request to come in before we expire
3574 if (cfq_should_wait_busy(cfqd, cfqq)) {
3575 unsigned long extend_sl = cfqd->cfq_slice_idle;
3576 if (!cfqd->cfq_slice_idle)
3577 extend_sl = cfqd->cfq_group_idle;
3578 cfqq->slice_end = jiffies + extend_sl;
3579 cfq_mark_cfqq_wait_busy(cfqq);
3580 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3584 * Idling is not enabled on:
3586 * - idle-priority queues
3588 * - queues with still some requests queued
3589 * - when there is a close cooperator
3591 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3592 cfq_slice_expired(cfqd, 1);
3593 else if (sync && cfqq_empty &&
3594 !cfq_close_cooperator(cfqd, cfqq)) {
3595 cfq_arm_slice_timer(cfqd);
3599 if (!cfqd->rq_in_driver)
3600 cfq_schedule_dispatch(cfqd);
3603 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3605 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3606 cfq_mark_cfqq_must_alloc_slice(cfqq);
3607 return ELV_MQUEUE_MUST;
3610 return ELV_MQUEUE_MAY;
3613 static int cfq_may_queue(struct request_queue *q, int rw)
3615 struct cfq_data *cfqd = q->elevator->elevator_data;
3616 struct task_struct *tsk = current;
3617 struct cfq_io_context *cic;
3618 struct cfq_queue *cfqq;
3621 * don't force setup of a queue from here, as a call to may_queue
3622 * does not necessarily imply that a request actually will be queued.
3623 * so just lookup a possibly existing queue, or return 'may queue'
3626 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3628 return ELV_MQUEUE_MAY;
3630 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3632 cfq_init_prio_data(cfqq, cic->ioc);
3634 return __cfq_may_queue(cfqq);
3637 return ELV_MQUEUE_MAY;
3641 * queue lock held here
3643 static void cfq_put_request(struct request *rq)
3645 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3648 const int rw = rq_data_dir(rq);
3650 BUG_ON(!cfqq->allocated[rw]);
3651 cfqq->allocated[rw]--;
3653 put_io_context(RQ_CIC(rq)->ioc);
3655 rq->elevator_private[0] = NULL;
3656 rq->elevator_private[1] = NULL;
3658 /* Put down rq reference on cfqg */
3659 cfq_put_cfqg(RQ_CFQG(rq));
3660 rq->elevator_private[2] = NULL;
3662 cfq_put_queue(cfqq);
3666 static struct cfq_queue *
3667 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3668 struct cfq_queue *cfqq)
3670 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3671 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3672 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3673 cfq_put_queue(cfqq);
3674 return cic_to_cfqq(cic, 1);
3678 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3679 * was the last process referring to said cfqq.
3681 static struct cfq_queue *
3682 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3684 if (cfqq_process_refs(cfqq) == 1) {
3685 cfqq->pid = current->pid;
3686 cfq_clear_cfqq_coop(cfqq);
3687 cfq_clear_cfqq_split_coop(cfqq);
3691 cic_set_cfqq(cic, NULL, 1);
3693 cfq_put_cooperator(cfqq);
3695 cfq_put_queue(cfqq);
3699 * Allocate cfq data structures associated with this request.
3702 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3704 struct cfq_data *cfqd = q->elevator->elevator_data;
3705 struct cfq_io_context *cic;
3706 const int rw = rq_data_dir(rq);
3707 const bool is_sync = rq_is_sync(rq);
3708 struct cfq_queue *cfqq;
3709 unsigned long flags;
3711 might_sleep_if(gfp_mask & __GFP_WAIT);
3713 cic = cfq_get_io_context(cfqd, gfp_mask);
3715 spin_lock_irqsave(q->queue_lock, flags);
3721 cfqq = cic_to_cfqq(cic, is_sync);
3722 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3723 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3724 cic_set_cfqq(cic, cfqq, is_sync);
3727 * If the queue was seeky for too long, break it apart.
3729 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3730 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3731 cfqq = split_cfqq(cic, cfqq);
3737 * Check to see if this queue is scheduled to merge with
3738 * another, closely cooperating queue. The merging of
3739 * queues happens here as it must be done in process context.
3740 * The reference on new_cfqq was taken in merge_cfqqs.
3743 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3746 cfqq->allocated[rw]++;
3749 rq->elevator_private[0] = cic;
3750 rq->elevator_private[1] = cfqq;
3751 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3752 spin_unlock_irqrestore(q->queue_lock, flags);
3756 cfq_schedule_dispatch(cfqd);
3757 spin_unlock_irqrestore(q->queue_lock, flags);
3758 cfq_log(cfqd, "set_request fail");
3762 static void cfq_kick_queue(struct work_struct *work)
3764 struct cfq_data *cfqd =
3765 container_of(work, struct cfq_data, unplug_work);
3766 struct request_queue *q = cfqd->queue;
3768 spin_lock_irq(q->queue_lock);
3769 __blk_run_queue(cfqd->queue);
3770 spin_unlock_irq(q->queue_lock);
3774 * Timer running if the active_queue is currently idling inside its time slice
3776 static void cfq_idle_slice_timer(unsigned long data)
3778 struct cfq_data *cfqd = (struct cfq_data *) data;
3779 struct cfq_queue *cfqq;
3780 unsigned long flags;
3783 cfq_log(cfqd, "idle timer fired");
3785 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3787 cfqq = cfqd->active_queue;
3792 * We saw a request before the queue expired, let it through
3794 if (cfq_cfqq_must_dispatch(cfqq))
3800 if (cfq_slice_used(cfqq))
3804 * only expire and reinvoke request handler, if there are
3805 * other queues with pending requests
3807 if (!cfqd->busy_queues)
3811 * not expired and it has a request pending, let it dispatch
3813 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3817 * Queue depth flag is reset only when the idle didn't succeed
3819 cfq_clear_cfqq_deep(cfqq);
3822 cfq_slice_expired(cfqd, timed_out);
3824 cfq_schedule_dispatch(cfqd);
3826 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3829 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3831 del_timer_sync(&cfqd->idle_slice_timer);
3832 cancel_work_sync(&cfqd->unplug_work);
3835 static void cfq_put_async_queues(struct cfq_data *cfqd)
3839 for (i = 0; i < IOPRIO_BE_NR; i++) {
3840 if (cfqd->async_cfqq[0][i])
3841 cfq_put_queue(cfqd->async_cfqq[0][i]);
3842 if (cfqd->async_cfqq[1][i])
3843 cfq_put_queue(cfqd->async_cfqq[1][i]);
3846 if (cfqd->async_idle_cfqq)
3847 cfq_put_queue(cfqd->async_idle_cfqq);
3850 static void cfq_exit_queue(struct elevator_queue *e)
3852 struct cfq_data *cfqd = e->elevator_data;
3853 struct request_queue *q = cfqd->queue;
3856 cfq_shutdown_timer_wq(cfqd);
3858 spin_lock_irq(q->queue_lock);
3860 if (cfqd->active_queue)
3861 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3863 while (!list_empty(&cfqd->cic_list)) {
3864 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3865 struct cfq_io_context,
3868 __cfq_exit_single_io_context(cfqd, cic);
3871 cfq_put_async_queues(cfqd);
3872 cfq_release_cfq_groups(cfqd);
3875 * If there are groups which we could not unlink from blkcg list,
3876 * wait for a rcu period for them to be freed.
3878 if (cfqd->nr_blkcg_linked_grps)
3881 spin_unlock_irq(q->queue_lock);
3883 cfq_shutdown_timer_wq(cfqd);
3885 spin_lock(&cic_index_lock);
3886 ida_remove(&cic_index_ida, cfqd->cic_index);
3887 spin_unlock(&cic_index_lock);
3890 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3891 * Do this wait only if there are other unlinked groups out
3892 * there. This can happen if cgroup deletion path claimed the
3893 * responsibility of cleaning up a group before queue cleanup code
3896 * Do not call synchronize_rcu() unconditionally as there are drivers
3897 * which create/delete request queue hundreds of times during scan/boot
3898 * and synchronize_rcu() can take significant time and slow down boot.
3903 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3904 /* Free up per cpu stats for root group */
3905 free_percpu(cfqd->root_group.blkg.stats_cpu);
3910 static int cfq_alloc_cic_index(void)
3915 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3918 spin_lock(&cic_index_lock);
3919 error = ida_get_new(&cic_index_ida, &index);
3920 spin_unlock(&cic_index_lock);
3921 if (error && error != -EAGAIN)
3928 static void *cfq_init_queue(struct request_queue *q)
3930 struct cfq_data *cfqd;
3932 struct cfq_group *cfqg;
3933 struct cfq_rb_root *st;
3935 i = cfq_alloc_cic_index();
3939 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3941 spin_lock(&cic_index_lock);
3942 ida_remove(&cic_index_ida, i);
3943 spin_unlock(&cic_index_lock);
3948 * Don't need take queue_lock in the routine, since we are
3949 * initializing the ioscheduler, and nobody is using cfqd
3951 cfqd->cic_index = i;
3953 /* Init root service tree */
3954 cfqd->grp_service_tree = CFQ_RB_ROOT;
3956 /* Init root group */
3957 cfqg = &cfqd->root_group;
3958 for_each_cfqg_st(cfqg, i, j, st)
3960 RB_CLEAR_NODE(&cfqg->rb_node);
3962 /* Give preference to root group over other groups */
3963 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3965 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3967 * Set root group reference to 2. One reference will be dropped when
3968 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3969 * Other reference will remain there as we don't want to delete this
3970 * group as it is statically allocated and gets destroyed when
3971 * throtl_data goes away.
3975 if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
3983 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3986 cfqd->nr_blkcg_linked_grps++;
3988 /* Add group on cfqd->cfqg_list */
3989 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
3992 * Not strictly needed (since RB_ROOT just clears the node and we
3993 * zeroed cfqd on alloc), but better be safe in case someone decides
3994 * to add magic to the rb code
3996 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3997 cfqd->prio_trees[i] = RB_ROOT;
4000 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4001 * Grab a permanent reference to it, so that the normal code flow
4002 * will not attempt to free it.
4004 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4005 cfqd->oom_cfqq.ref++;
4006 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
4008 INIT_LIST_HEAD(&cfqd->cic_list);
4012 init_timer(&cfqd->idle_slice_timer);
4013 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4014 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4016 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4018 cfqd->cfq_quantum = cfq_quantum;
4019 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4020 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4021 cfqd->cfq_back_max = cfq_back_max;
4022 cfqd->cfq_back_penalty = cfq_back_penalty;
4023 cfqd->cfq_slice[0] = cfq_slice_async;
4024 cfqd->cfq_slice[1] = cfq_slice_sync;
4025 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4026 cfqd->cfq_slice_idle = cfq_slice_idle;
4027 cfqd->cfq_group_idle = cfq_group_idle;
4028 cfqd->cfq_latency = 1;
4031 * we optimistically start assuming sync ops weren't delayed in last
4032 * second, in order to have larger depth for async operations.
4034 cfqd->last_delayed_sync = jiffies - HZ;
4038 static void cfq_slab_kill(void)
4041 * Caller already ensured that pending RCU callbacks are completed,
4042 * so we should have no busy allocations at this point.
4045 kmem_cache_destroy(cfq_pool);
4047 kmem_cache_destroy(cfq_ioc_pool);
4050 static int __init cfq_slab_setup(void)
4052 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4056 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
4067 * sysfs parts below -->
4070 cfq_var_show(unsigned int var, char *page)
4072 return sprintf(page, "%d\n", var);
4076 cfq_var_store(unsigned int *var, const char *page, size_t count)
4078 char *p = (char *) page;
4080 *var = simple_strtoul(p, &p, 10);
4084 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4085 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4087 struct cfq_data *cfqd = e->elevator_data; \
4088 unsigned int __data = __VAR; \
4090 __data = jiffies_to_msecs(__data); \
4091 return cfq_var_show(__data, (page)); \
4093 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4094 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4095 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4096 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4097 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4098 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4099 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4100 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4101 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4102 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4103 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4104 #undef SHOW_FUNCTION
4106 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4107 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4109 struct cfq_data *cfqd = e->elevator_data; \
4110 unsigned int __data; \
4111 int ret = cfq_var_store(&__data, (page), count); \
4112 if (__data < (MIN)) \
4114 else if (__data > (MAX)) \
4117 *(__PTR) = msecs_to_jiffies(__data); \
4119 *(__PTR) = __data; \
4122 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4123 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4125 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4127 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4128 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4130 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4131 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4132 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4133 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4134 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4136 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4137 #undef STORE_FUNCTION
4139 #define CFQ_ATTR(name) \
4140 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4142 static struct elv_fs_entry cfq_attrs[] = {
4144 CFQ_ATTR(fifo_expire_sync),
4145 CFQ_ATTR(fifo_expire_async),
4146 CFQ_ATTR(back_seek_max),
4147 CFQ_ATTR(back_seek_penalty),
4148 CFQ_ATTR(slice_sync),
4149 CFQ_ATTR(slice_async),
4150 CFQ_ATTR(slice_async_rq),
4151 CFQ_ATTR(slice_idle),
4152 CFQ_ATTR(group_idle),
4153 CFQ_ATTR(low_latency),
4157 static struct elevator_type iosched_cfq = {
4159 .elevator_merge_fn = cfq_merge,
4160 .elevator_merged_fn = cfq_merged_request,
4161 .elevator_merge_req_fn = cfq_merged_requests,
4162 .elevator_allow_merge_fn = cfq_allow_merge,
4163 .elevator_bio_merged_fn = cfq_bio_merged,
4164 .elevator_dispatch_fn = cfq_dispatch_requests,
4165 .elevator_add_req_fn = cfq_insert_request,
4166 .elevator_activate_req_fn = cfq_activate_request,
4167 .elevator_deactivate_req_fn = cfq_deactivate_request,
4168 .elevator_completed_req_fn = cfq_completed_request,
4169 .elevator_former_req_fn = elv_rb_former_request,
4170 .elevator_latter_req_fn = elv_rb_latter_request,
4171 .elevator_set_req_fn = cfq_set_request,
4172 .elevator_put_req_fn = cfq_put_request,
4173 .elevator_may_queue_fn = cfq_may_queue,
4174 .elevator_init_fn = cfq_init_queue,
4175 .elevator_exit_fn = cfq_exit_queue,
4176 .trim = cfq_free_io_context,
4178 .elevator_attrs = cfq_attrs,
4179 .elevator_name = "cfq",
4180 .elevator_owner = THIS_MODULE,
4183 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4184 static struct blkio_policy_type blkio_policy_cfq = {
4186 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4187 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4189 .plid = BLKIO_POLICY_PROP,
4192 static struct blkio_policy_type blkio_policy_cfq;
4195 static int __init cfq_init(void)
4198 * could be 0 on HZ < 1000 setups
4200 if (!cfq_slice_async)
4201 cfq_slice_async = 1;
4202 if (!cfq_slice_idle)
4205 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4206 if (!cfq_group_idle)
4211 if (cfq_slab_setup())
4214 elv_register(&iosched_cfq);
4215 blkio_policy_register(&blkio_policy_cfq);
4220 static void __exit cfq_exit(void)
4222 DECLARE_COMPLETION_ONSTACK(all_gone);
4223 blkio_policy_unregister(&blkio_policy_cfq);
4224 elv_unregister(&iosched_cfq);
4225 ioc_gone = &all_gone;
4226 /* ioc_gone's update must be visible before reading ioc_count */
4230 * this also protects us from entering cfq_slab_kill() with
4231 * pending RCU callbacks
4233 if (elv_ioc_count_read(cfq_ioc_count))
4234 wait_for_completion(&all_gone);
4235 ida_destroy(&cic_index_ida);
4239 module_init(cfq_init);
4240 module_exit(cfq_exit);
4242 MODULE_AUTHOR("Jens Axboe");
4243 MODULE_LICENSE("GPL");
4244 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");