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>
23 /* max queue in one round of service */
24 static const int cfq_quantum = 8;
25 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max = 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty = 2;
30 static const int cfq_slice_sync = HZ / 10;
31 static int cfq_slice_async = HZ / 25;
32 static const int cfq_slice_async_rq = 2;
33 static int cfq_slice_idle = HZ / 125;
34 static int cfq_group_idle = HZ / 125;
35 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36 static const int cfq_hist_divisor = 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
58 ((struct cfq_io_context *) (rq)->elevator_private[0])
59 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
60 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
62 static struct kmem_cache *cfq_pool;
63 static struct kmem_cache *cfq_ioc_pool;
65 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
66 static struct completion *ioc_gone;
67 static DEFINE_SPINLOCK(ioc_gone_lock);
69 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
70 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
71 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
73 #define sample_valid(samples) ((samples) > 80)
74 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
77 * Most of our rbtree usage is for sorting with min extraction, so
78 * if we cache the leftmost node we don't have to walk down the tree
79 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
80 * move this into the elevator for the rq sorting as well.
86 unsigned total_weight;
88 struct cfq_ttime ttime;
90 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
91 .ttime = {.last_end_request = jiffies,},}
94 * Per process-grouping structure
99 /* various state flags, see below */
101 /* parent cfq_data */
102 struct cfq_data *cfqd;
103 /* service_tree member */
104 struct rb_node rb_node;
105 /* service_tree key */
106 unsigned long rb_key;
107 /* prio tree member */
108 struct rb_node p_node;
109 /* prio tree root we belong to, if any */
110 struct rb_root *p_root;
111 /* sorted list of pending requests */
112 struct rb_root sort_list;
113 /* if fifo isn't expired, next request to serve */
114 struct request *next_rq;
115 /* requests queued in sort_list */
117 /* currently allocated requests */
119 /* fifo list of requests in sort_list */
120 struct list_head fifo;
122 /* time when queue got scheduled in to dispatch first request. */
123 unsigned long dispatch_start;
124 unsigned int allocated_slice;
125 unsigned int slice_dispatch;
126 /* time when first request from queue completed and slice started. */
127 unsigned long slice_start;
128 unsigned long slice_end;
131 /* pending priority requests */
133 /* number of requests that are on the dispatch list or inside driver */
136 /* io prio of this group */
137 unsigned short ioprio, org_ioprio;
138 unsigned short ioprio_class;
143 sector_t last_request_pos;
145 struct cfq_rb_root *service_tree;
146 struct cfq_queue *new_cfqq;
147 struct cfq_group *cfqg;
148 /* Number of sectors dispatched from queue in single dispatch round */
149 unsigned long nr_sectors;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
164 * Second index in the service_trees.
168 SYNC_NOIDLE_WORKLOAD = 1,
172 /* This is per cgroup per device grouping structure */
174 /* group service_tree member */
175 struct rb_node rb_node;
177 /* group service_tree key */
180 unsigned int new_weight;
183 /* number of cfqq currently on this group */
187 * Per group busy queues average. Useful for workload slice calc. We
188 * create the array for each prio class but at run time it is used
189 * only for RT and BE class and slot for IDLE class remains unused.
190 * This is primarily done to avoid confusion and a gcc warning.
192 unsigned int busy_queues_avg[CFQ_PRIO_NR];
194 * rr lists of queues with requests. We maintain service trees for
195 * RT and BE classes. These trees are subdivided in subclasses
196 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
197 * class there is no subclassification and all the cfq queues go on
198 * a single tree service_tree_idle.
199 * Counts are embedded in the cfq_rb_root
201 struct cfq_rb_root service_trees[2][3];
202 struct cfq_rb_root service_tree_idle;
204 unsigned long saved_workload_slice;
205 enum wl_type_t saved_workload;
206 enum wl_prio_t saved_serving_prio;
207 struct blkio_group blkg;
208 #ifdef CONFIG_CFQ_GROUP_IOSCHED
209 struct hlist_node cfqd_node;
212 /* number of requests that are on the dispatch list or inside driver */
214 struct cfq_ttime ttime;
218 * Per block device queue structure
221 struct request_queue *queue;
222 /* Root service tree for cfq_groups */
223 struct cfq_rb_root grp_service_tree;
224 struct cfq_group root_group;
227 * The priority currently being served
229 enum wl_prio_t serving_prio;
230 enum wl_type_t serving_type;
231 unsigned long workload_expires;
232 struct cfq_group *serving_group;
235 * Each priority tree is sorted by next_request position. These
236 * trees are used when determining if two or more queues are
237 * interleaving requests (see cfq_close_cooperator).
239 struct rb_root prio_trees[CFQ_PRIO_LISTS];
241 unsigned int busy_queues;
242 unsigned int busy_sync_queues;
248 * queue-depth detection
254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
258 int hw_tag_est_depth;
259 unsigned int hw_tag_samples;
262 * idle window management
264 struct timer_list idle_slice_timer;
265 struct work_struct unplug_work;
267 struct cfq_queue *active_queue;
268 struct cfq_io_context *active_cic;
271 * async queue for each priority case
273 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
274 struct cfq_queue *async_idle_cfqq;
276 sector_t last_position;
279 * tunables, see top of file
281 unsigned int cfq_quantum;
282 unsigned int cfq_fifo_expire[2];
283 unsigned int cfq_back_penalty;
284 unsigned int cfq_back_max;
285 unsigned int cfq_slice[2];
286 unsigned int cfq_slice_async_rq;
287 unsigned int cfq_slice_idle;
288 unsigned int cfq_group_idle;
289 unsigned int cfq_latency;
291 struct list_head cic_list;
294 * Fallback dummy cfqq for extreme OOM conditions
296 struct cfq_queue oom_cfqq;
298 unsigned long last_delayed_sync;
300 /* List of cfq groups being managed on this device*/
301 struct hlist_head cfqg_list;
303 /* Number of groups which are on blkcg->blkg_list */
304 unsigned int nr_blkcg_linked_grps;
307 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
309 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
316 if (prio == IDLE_WORKLOAD)
317 return &cfqg->service_tree_idle;
319 return &cfqg->service_trees[prio][type];
322 enum cfqq_state_flags {
323 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
324 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
325 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
326 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
327 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
328 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
329 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
330 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
331 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
332 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
333 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
334 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
335 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
338 #define CFQ_CFQQ_FNS(name) \
339 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
343 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
345 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
347 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
349 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
353 CFQ_CFQQ_FNS(wait_request);
354 CFQ_CFQQ_FNS(must_dispatch);
355 CFQ_CFQQ_FNS(must_alloc_slice);
356 CFQ_CFQQ_FNS(fifo_expire);
357 CFQ_CFQQ_FNS(idle_window);
358 CFQ_CFQQ_FNS(prio_changed);
359 CFQ_CFQQ_FNS(slice_new);
362 CFQ_CFQQ_FNS(split_coop);
364 CFQ_CFQQ_FNS(wait_busy);
367 #ifdef CONFIG_CFQ_GROUP_IOSCHED
368 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
369 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
370 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
371 blkg_path(&(cfqq)->cfqg->blkg), ##args)
373 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
374 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
375 blkg_path(&(cfqg)->blkg), ##args) \
378 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
380 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
382 #define cfq_log(cfqd, fmt, args...) \
383 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
385 /* Traverses through cfq group service trees */
386 #define for_each_cfqg_st(cfqg, i, j, st) \
387 for (i = 0; i <= IDLE_WORKLOAD; i++) \
388 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
389 : &cfqg->service_tree_idle; \
390 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
391 (i == IDLE_WORKLOAD && j == 0); \
392 j++, st = i < IDLE_WORKLOAD ? \
393 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
396 struct cfq_ttime *ttime, bool group_idle)
399 if (!sample_valid(ttime->ttime_samples))
402 slice = cfqd->cfq_group_idle;
404 slice = cfqd->cfq_slice_idle;
405 return ttime->ttime_mean > slice;
408 static inline bool iops_mode(struct cfq_data *cfqd)
411 * If we are not idling on queues and it is a NCQ drive, parallel
412 * execution of requests is on and measuring time is not possible
413 * in most of the cases until and unless we drive shallower queue
414 * depths and that becomes a performance bottleneck. In such cases
415 * switch to start providing fairness in terms of number of IOs.
417 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
423 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
425 if (cfq_class_idle(cfqq))
426 return IDLE_WORKLOAD;
427 if (cfq_class_rt(cfqq))
433 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
435 if (!cfq_cfqq_sync(cfqq))
436 return ASYNC_WORKLOAD;
437 if (!cfq_cfqq_idle_window(cfqq))
438 return SYNC_NOIDLE_WORKLOAD;
439 return SYNC_WORKLOAD;
442 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
443 struct cfq_data *cfqd,
444 struct cfq_group *cfqg)
446 if (wl == IDLE_WORKLOAD)
447 return cfqg->service_tree_idle.count;
449 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
450 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
451 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
454 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
455 struct cfq_group *cfqg)
457 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
458 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
461 static void cfq_dispatch_insert(struct request_queue *, struct request *);
462 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
463 struct io_context *, gfp_t);
464 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
465 struct io_context *);
467 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
470 return cic->cfqq[is_sync];
473 static inline void cic_set_cfqq(struct cfq_io_context *cic,
474 struct cfq_queue *cfqq, bool is_sync)
476 cic->cfqq[is_sync] = cfqq;
479 #define CIC_DEAD_KEY 1ul
480 #define CIC_DEAD_INDEX_SHIFT 1
482 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
484 return (void *)(cfqd->queue->id << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
487 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
489 struct cfq_data *cfqd = cic->key;
491 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
498 * We regard a request as SYNC, if it's either a read or has the SYNC bit
499 * set (in which case it could also be direct WRITE).
501 static inline bool cfq_bio_sync(struct bio *bio)
503 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
507 * scheduler run of queue, if there are requests pending and no one in the
508 * driver that will restart queueing
510 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
512 if (cfqd->busy_queues) {
513 cfq_log(cfqd, "schedule dispatch");
514 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
519 * Scale schedule slice based on io priority. Use the sync time slice only
520 * if a queue is marked sync and has sync io queued. A sync queue with async
521 * io only, should not get full sync slice length.
523 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
526 const int base_slice = cfqd->cfq_slice[sync];
528 WARN_ON(prio >= IOPRIO_BE_NR);
530 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
534 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
536 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
539 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
541 u64 d = delta << CFQ_SERVICE_SHIFT;
543 d = d * BLKIO_WEIGHT_DEFAULT;
544 do_div(d, cfqg->weight);
548 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
550 s64 delta = (s64)(vdisktime - min_vdisktime);
552 min_vdisktime = vdisktime;
554 return min_vdisktime;
557 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
559 s64 delta = (s64)(vdisktime - min_vdisktime);
561 min_vdisktime = vdisktime;
563 return min_vdisktime;
566 static void update_min_vdisktime(struct cfq_rb_root *st)
568 struct cfq_group *cfqg;
571 cfqg = rb_entry_cfqg(st->left);
572 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
578 * get averaged number of queues of RT/BE priority.
579 * average is updated, with a formula that gives more weight to higher numbers,
580 * to quickly follows sudden increases and decrease slowly
583 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
584 struct cfq_group *cfqg, bool rt)
586 unsigned min_q, max_q;
587 unsigned mult = cfq_hist_divisor - 1;
588 unsigned round = cfq_hist_divisor / 2;
589 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
591 min_q = min(cfqg->busy_queues_avg[rt], busy);
592 max_q = max(cfqg->busy_queues_avg[rt], busy);
593 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
595 return cfqg->busy_queues_avg[rt];
598 static inline unsigned
599 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
601 struct cfq_rb_root *st = &cfqd->grp_service_tree;
603 return cfq_target_latency * cfqg->weight / st->total_weight;
606 static inline unsigned
607 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
609 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
610 if (cfqd->cfq_latency) {
612 * interested queues (we consider only the ones with the same
613 * priority class in the cfq group)
615 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
617 unsigned sync_slice = cfqd->cfq_slice[1];
618 unsigned expect_latency = sync_slice * iq;
619 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
621 if (expect_latency > group_slice) {
622 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
623 /* scale low_slice according to IO priority
624 * and sync vs async */
626 min(slice, base_low_slice * slice / sync_slice);
627 /* the adapted slice value is scaled to fit all iqs
628 * into the target latency */
629 slice = max(slice * group_slice / expect_latency,
637 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
639 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
641 cfqq->slice_start = jiffies;
642 cfqq->slice_end = jiffies + slice;
643 cfqq->allocated_slice = slice;
644 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
648 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
649 * isn't valid until the first request from the dispatch is activated
650 * and the slice time set.
652 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
654 if (cfq_cfqq_slice_new(cfqq))
656 if (time_before(jiffies, cfqq->slice_end))
663 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
664 * We choose the request that is closest to the head right now. Distance
665 * behind the head is penalized and only allowed to a certain extent.
667 static struct request *
668 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
670 sector_t s1, s2, d1 = 0, d2 = 0;
671 unsigned long back_max;
672 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
673 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
674 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
676 if (rq1 == NULL || rq1 == rq2)
681 if (rq_is_sync(rq1) != rq_is_sync(rq2))
682 return rq_is_sync(rq1) ? rq1 : rq2;
684 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
685 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
687 s1 = blk_rq_pos(rq1);
688 s2 = blk_rq_pos(rq2);
691 * by definition, 1KiB is 2 sectors
693 back_max = cfqd->cfq_back_max * 2;
696 * Strict one way elevator _except_ in the case where we allow
697 * short backward seeks which are biased as twice the cost of a
698 * similar forward seek.
702 else if (s1 + back_max >= last)
703 d1 = (last - s1) * cfqd->cfq_back_penalty;
705 wrap |= CFQ_RQ1_WRAP;
709 else if (s2 + back_max >= last)
710 d2 = (last - s2) * cfqd->cfq_back_penalty;
712 wrap |= CFQ_RQ2_WRAP;
714 /* Found required data */
717 * By doing switch() on the bit mask "wrap" we avoid having to
718 * check two variables for all permutations: --> faster!
721 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
737 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
740 * Since both rqs are wrapped,
741 * start with the one that's further behind head
742 * (--> only *one* back seek required),
743 * since back seek takes more time than forward.
753 * The below is leftmost cache rbtree addon
755 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
757 /* Service tree is empty */
762 root->left = rb_first(&root->rb);
765 return rb_entry(root->left, struct cfq_queue, rb_node);
770 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
773 root->left = rb_first(&root->rb);
776 return rb_entry_cfqg(root->left);
781 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
787 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
791 rb_erase_init(n, &root->rb);
796 * would be nice to take fifo expire time into account as well
798 static struct request *
799 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
800 struct request *last)
802 struct rb_node *rbnext = rb_next(&last->rb_node);
803 struct rb_node *rbprev = rb_prev(&last->rb_node);
804 struct request *next = NULL, *prev = NULL;
806 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
809 prev = rb_entry_rq(rbprev);
812 next = rb_entry_rq(rbnext);
814 rbnext = rb_first(&cfqq->sort_list);
815 if (rbnext && rbnext != &last->rb_node)
816 next = rb_entry_rq(rbnext);
819 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
822 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
823 struct cfq_queue *cfqq)
826 * just an approximation, should be ok.
828 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
829 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
833 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
835 return cfqg->vdisktime - st->min_vdisktime;
839 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
841 struct rb_node **node = &st->rb.rb_node;
842 struct rb_node *parent = NULL;
843 struct cfq_group *__cfqg;
844 s64 key = cfqg_key(st, cfqg);
847 while (*node != NULL) {
849 __cfqg = rb_entry_cfqg(parent);
851 if (key < cfqg_key(st, __cfqg))
852 node = &parent->rb_left;
854 node = &parent->rb_right;
860 st->left = &cfqg->rb_node;
862 rb_link_node(&cfqg->rb_node, parent, node);
863 rb_insert_color(&cfqg->rb_node, &st->rb);
867 cfq_update_group_weight(struct cfq_group *cfqg)
869 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
870 if (cfqg->needs_update) {
871 cfqg->weight = cfqg->new_weight;
872 cfqg->needs_update = false;
877 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
879 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
881 cfq_update_group_weight(cfqg);
882 __cfq_group_service_tree_add(st, cfqg);
883 st->total_weight += cfqg->weight;
887 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
889 struct cfq_rb_root *st = &cfqd->grp_service_tree;
890 struct cfq_group *__cfqg;
894 if (!RB_EMPTY_NODE(&cfqg->rb_node))
898 * Currently put the group at the end. Later implement something
899 * so that groups get lesser vtime based on their weights, so that
900 * if group does not loose all if it was not continuously backlogged.
902 n = rb_last(&st->rb);
904 __cfqg = rb_entry_cfqg(n);
905 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
907 cfqg->vdisktime = st->min_vdisktime;
908 cfq_group_service_tree_add(st, cfqg);
912 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
914 st->total_weight -= cfqg->weight;
915 if (!RB_EMPTY_NODE(&cfqg->rb_node))
916 cfq_rb_erase(&cfqg->rb_node, st);
920 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
922 struct cfq_rb_root *st = &cfqd->grp_service_tree;
924 BUG_ON(cfqg->nr_cfqq < 1);
927 /* If there are other cfq queues under this group, don't delete it */
931 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
932 cfq_group_service_tree_del(st, cfqg);
933 cfqg->saved_workload_slice = 0;
934 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
937 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
938 unsigned int *unaccounted_time)
940 unsigned int slice_used;
943 * Queue got expired before even a single request completed or
944 * got expired immediately after first request completion.
946 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
948 * Also charge the seek time incurred to the group, otherwise
949 * if there are mutiple queues in the group, each can dispatch
950 * a single request on seeky media and cause lots of seek time
951 * and group will never know it.
953 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
956 slice_used = jiffies - cfqq->slice_start;
957 if (slice_used > cfqq->allocated_slice) {
958 *unaccounted_time = slice_used - cfqq->allocated_slice;
959 slice_used = cfqq->allocated_slice;
961 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
962 *unaccounted_time += cfqq->slice_start -
963 cfqq->dispatch_start;
969 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
970 struct cfq_queue *cfqq)
972 struct cfq_rb_root *st = &cfqd->grp_service_tree;
973 unsigned int used_sl, charge, unaccounted_sl = 0;
974 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
975 - cfqg->service_tree_idle.count;
978 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
981 charge = cfqq->slice_dispatch;
982 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
983 charge = cfqq->allocated_slice;
985 /* Can't update vdisktime while group is on service tree */
986 cfq_group_service_tree_del(st, cfqg);
987 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
988 /* If a new weight was requested, update now, off tree */
989 cfq_group_service_tree_add(st, cfqg);
991 /* This group is being expired. Save the context */
992 if (time_after(cfqd->workload_expires, jiffies)) {
993 cfqg->saved_workload_slice = cfqd->workload_expires
995 cfqg->saved_workload = cfqd->serving_type;
996 cfqg->saved_serving_prio = cfqd->serving_prio;
998 cfqg->saved_workload_slice = 0;
1000 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1002 cfq_log_cfqq(cfqq->cfqd, cfqq,
1003 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1004 used_sl, cfqq->slice_dispatch, charge,
1005 iops_mode(cfqd), cfqq->nr_sectors);
1006 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
1008 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
1011 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1012 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
1015 return container_of(blkg, struct cfq_group, blkg);
1019 static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1020 unsigned int weight)
1022 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1023 cfqg->new_weight = weight;
1024 cfqg->needs_update = true;
1027 static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
1028 struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
1030 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1031 unsigned int major, minor;
1034 * Add group onto cgroup list. It might happen that bdi->dev is
1035 * not initialized yet. Initialize this new group without major
1036 * and minor info and this info will be filled in once a new thread
1040 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1041 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1042 (void *)cfqd, MKDEV(major, minor));
1044 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1047 cfqd->nr_blkcg_linked_grps++;
1048 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1050 /* Add group on cfqd list */
1051 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1055 * Should be called from sleepable context. No request queue lock as per
1056 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1057 * from sleepable context.
1059 static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
1061 struct cfq_group *cfqg = NULL;
1063 struct cfq_rb_root *st;
1065 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1069 for_each_cfqg_st(cfqg, i, j, st)
1071 RB_CLEAR_NODE(&cfqg->rb_node);
1073 cfqg->ttime.last_end_request = jiffies;
1076 * Take the initial reference that will be released on destroy
1077 * This can be thought of a joint reference by cgroup and
1078 * elevator which will be dropped by either elevator exit
1079 * or cgroup deletion path depending on who is exiting first.
1083 ret = blkio_alloc_blkg_stats(&cfqg->blkg);
1092 static struct cfq_group *
1093 cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
1095 struct cfq_group *cfqg = NULL;
1097 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1098 unsigned int major, minor;
1101 * This is the common case when there are no blkio cgroups.
1102 * Avoid lookup in this case
1104 if (blkcg == &blkio_root_cgroup)
1105 cfqg = &cfqd->root_group;
1107 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1109 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1110 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1111 cfqg->blkg.dev = MKDEV(major, minor);
1118 * Search for the cfq group current task belongs to. request_queue lock must
1121 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1123 struct blkio_cgroup *blkcg;
1124 struct cfq_group *cfqg = NULL, *__cfqg = NULL;
1125 struct request_queue *q = cfqd->queue;
1128 blkcg = task_blkio_cgroup(current);
1129 cfqg = cfq_find_cfqg(cfqd, blkcg);
1136 * Need to allocate a group. Allocation of group also needs allocation
1137 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1138 * we need to drop rcu lock and queue_lock before we call alloc.
1140 * Not taking any queue reference here and assuming that queue is
1141 * around by the time we return. CFQ queue allocation code does
1142 * the same. It might be racy though.
1146 spin_unlock_irq(q->queue_lock);
1148 cfqg = cfq_alloc_cfqg(cfqd);
1150 spin_lock_irq(q->queue_lock);
1153 blkcg = task_blkio_cgroup(current);
1156 * If some other thread already allocated the group while we were
1157 * not holding queue lock, free up the group
1159 __cfqg = cfq_find_cfqg(cfqd, blkcg);
1168 cfqg = &cfqd->root_group;
1170 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
1175 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1181 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1183 /* Currently, all async queues are mapped to root group */
1184 if (!cfq_cfqq_sync(cfqq))
1185 cfqg = &cfqq->cfqd->root_group;
1188 /* cfqq reference on cfqg */
1192 static void cfq_put_cfqg(struct cfq_group *cfqg)
1194 struct cfq_rb_root *st;
1197 BUG_ON(cfqg->ref <= 0);
1201 for_each_cfqg_st(cfqg, i, j, st)
1202 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1203 free_percpu(cfqg->blkg.stats_cpu);
1207 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1209 /* Something wrong if we are trying to remove same group twice */
1210 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1212 hlist_del_init(&cfqg->cfqd_node);
1214 BUG_ON(cfqd->nr_blkcg_linked_grps <= 0);
1215 cfqd->nr_blkcg_linked_grps--;
1218 * Put the reference taken at the time of creation so that when all
1219 * queues are gone, group can be destroyed.
1224 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1226 struct hlist_node *pos, *n;
1227 struct cfq_group *cfqg;
1229 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1231 * If cgroup removal path got to blk_group first and removed
1232 * it from cgroup list, then it will take care of destroying
1235 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1236 cfq_destroy_cfqg(cfqd, cfqg);
1241 * Blk cgroup controller notification saying that blkio_group object is being
1242 * delinked as associated cgroup object is going away. That also means that
1243 * no new IO will come in this group. So get rid of this group as soon as
1244 * any pending IO in the group is finished.
1246 * This function is called under rcu_read_lock(). key is the rcu protected
1247 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1250 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1251 * it should not be NULL as even if elevator was exiting, cgroup deltion
1252 * path got to it first.
1254 static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1256 unsigned long flags;
1257 struct cfq_data *cfqd = key;
1259 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1260 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1261 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1264 #else /* GROUP_IOSCHED */
1265 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1267 return &cfqd->root_group;
1270 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1276 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1280 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1281 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1283 #endif /* GROUP_IOSCHED */
1286 * The cfqd->service_trees holds all pending cfq_queue's that have
1287 * requests waiting to be processed. It is sorted in the order that
1288 * we will service the queues.
1290 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1293 struct rb_node **p, *parent;
1294 struct cfq_queue *__cfqq;
1295 unsigned long rb_key;
1296 struct cfq_rb_root *service_tree;
1300 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1302 if (cfq_class_idle(cfqq)) {
1303 rb_key = CFQ_IDLE_DELAY;
1304 parent = rb_last(&service_tree->rb);
1305 if (parent && parent != &cfqq->rb_node) {
1306 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1307 rb_key += __cfqq->rb_key;
1310 } else if (!add_front) {
1312 * Get our rb key offset. Subtract any residual slice
1313 * value carried from last service. A negative resid
1314 * count indicates slice overrun, and this should position
1315 * the next service time further away in the tree.
1317 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1318 rb_key -= cfqq->slice_resid;
1319 cfqq->slice_resid = 0;
1322 __cfqq = cfq_rb_first(service_tree);
1323 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1326 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1329 * same position, nothing more to do
1331 if (rb_key == cfqq->rb_key &&
1332 cfqq->service_tree == service_tree)
1335 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1336 cfqq->service_tree = NULL;
1341 cfqq->service_tree = service_tree;
1342 p = &service_tree->rb.rb_node;
1347 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1350 * sort by key, that represents service time.
1352 if (time_before(rb_key, __cfqq->rb_key))
1355 n = &(*p)->rb_right;
1363 service_tree->left = &cfqq->rb_node;
1365 cfqq->rb_key = rb_key;
1366 rb_link_node(&cfqq->rb_node, parent, p);
1367 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1368 service_tree->count++;
1369 if (add_front || !new_cfqq)
1371 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1374 static struct cfq_queue *
1375 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1376 sector_t sector, struct rb_node **ret_parent,
1377 struct rb_node ***rb_link)
1379 struct rb_node **p, *parent;
1380 struct cfq_queue *cfqq = NULL;
1388 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1391 * Sort strictly based on sector. Smallest to the left,
1392 * largest to the right.
1394 if (sector > blk_rq_pos(cfqq->next_rq))
1395 n = &(*p)->rb_right;
1396 else if (sector < blk_rq_pos(cfqq->next_rq))
1404 *ret_parent = parent;
1410 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1412 struct rb_node **p, *parent;
1413 struct cfq_queue *__cfqq;
1416 rb_erase(&cfqq->p_node, cfqq->p_root);
1417 cfqq->p_root = NULL;
1420 if (cfq_class_idle(cfqq))
1425 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1426 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1427 blk_rq_pos(cfqq->next_rq), &parent, &p);
1429 rb_link_node(&cfqq->p_node, parent, p);
1430 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1432 cfqq->p_root = NULL;
1436 * Update cfqq's position in the service tree.
1438 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1441 * Resorting requires the cfqq to be on the RR list already.
1443 if (cfq_cfqq_on_rr(cfqq)) {
1444 cfq_service_tree_add(cfqd, cfqq, 0);
1445 cfq_prio_tree_add(cfqd, cfqq);
1450 * add to busy list of queues for service, trying to be fair in ordering
1451 * the pending list according to last request service
1453 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1455 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1456 BUG_ON(cfq_cfqq_on_rr(cfqq));
1457 cfq_mark_cfqq_on_rr(cfqq);
1458 cfqd->busy_queues++;
1459 if (cfq_cfqq_sync(cfqq))
1460 cfqd->busy_sync_queues++;
1462 cfq_resort_rr_list(cfqd, cfqq);
1466 * Called when the cfqq no longer has requests pending, remove it from
1469 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1471 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1472 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1473 cfq_clear_cfqq_on_rr(cfqq);
1475 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1476 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1477 cfqq->service_tree = NULL;
1480 rb_erase(&cfqq->p_node, cfqq->p_root);
1481 cfqq->p_root = NULL;
1484 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1485 BUG_ON(!cfqd->busy_queues);
1486 cfqd->busy_queues--;
1487 if (cfq_cfqq_sync(cfqq))
1488 cfqd->busy_sync_queues--;
1492 * rb tree support functions
1494 static void cfq_del_rq_rb(struct request *rq)
1496 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1497 const int sync = rq_is_sync(rq);
1499 BUG_ON(!cfqq->queued[sync]);
1500 cfqq->queued[sync]--;
1502 elv_rb_del(&cfqq->sort_list, rq);
1504 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1506 * Queue will be deleted from service tree when we actually
1507 * expire it later. Right now just remove it from prio tree
1511 rb_erase(&cfqq->p_node, cfqq->p_root);
1512 cfqq->p_root = NULL;
1517 static void cfq_add_rq_rb(struct request *rq)
1519 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1520 struct cfq_data *cfqd = cfqq->cfqd;
1521 struct request *prev;
1523 cfqq->queued[rq_is_sync(rq)]++;
1525 elv_rb_add(&cfqq->sort_list, rq);
1527 if (!cfq_cfqq_on_rr(cfqq))
1528 cfq_add_cfqq_rr(cfqd, cfqq);
1531 * check if this request is a better next-serve candidate
1533 prev = cfqq->next_rq;
1534 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1537 * adjust priority tree position, if ->next_rq changes
1539 if (prev != cfqq->next_rq)
1540 cfq_prio_tree_add(cfqd, cfqq);
1542 BUG_ON(!cfqq->next_rq);
1545 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1547 elv_rb_del(&cfqq->sort_list, rq);
1548 cfqq->queued[rq_is_sync(rq)]--;
1549 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1550 rq_data_dir(rq), rq_is_sync(rq));
1552 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1553 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1557 static struct request *
1558 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1560 struct task_struct *tsk = current;
1561 struct cfq_io_context *cic;
1562 struct cfq_queue *cfqq;
1564 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1568 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1570 sector_t sector = bio->bi_sector + bio_sectors(bio);
1572 return elv_rb_find(&cfqq->sort_list, sector);
1578 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1580 struct cfq_data *cfqd = q->elevator->elevator_data;
1582 cfqd->rq_in_driver++;
1583 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1584 cfqd->rq_in_driver);
1586 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1589 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1591 struct cfq_data *cfqd = q->elevator->elevator_data;
1593 WARN_ON(!cfqd->rq_in_driver);
1594 cfqd->rq_in_driver--;
1595 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1596 cfqd->rq_in_driver);
1599 static void cfq_remove_request(struct request *rq)
1601 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1603 if (cfqq->next_rq == rq)
1604 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1606 list_del_init(&rq->queuelist);
1609 cfqq->cfqd->rq_queued--;
1610 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1611 rq_data_dir(rq), rq_is_sync(rq));
1612 if (rq->cmd_flags & REQ_PRIO) {
1613 WARN_ON(!cfqq->prio_pending);
1614 cfqq->prio_pending--;
1618 static int cfq_merge(struct request_queue *q, struct request **req,
1621 struct cfq_data *cfqd = q->elevator->elevator_data;
1622 struct request *__rq;
1624 __rq = cfq_find_rq_fmerge(cfqd, bio);
1625 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1627 return ELEVATOR_FRONT_MERGE;
1630 return ELEVATOR_NO_MERGE;
1633 static void cfq_merged_request(struct request_queue *q, struct request *req,
1636 if (type == ELEVATOR_FRONT_MERGE) {
1637 struct cfq_queue *cfqq = RQ_CFQQ(req);
1639 cfq_reposition_rq_rb(cfqq, req);
1643 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1646 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1647 bio_data_dir(bio), cfq_bio_sync(bio));
1651 cfq_merged_requests(struct request_queue *q, struct request *rq,
1652 struct request *next)
1654 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1656 * reposition in fifo if next is older than rq
1658 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1659 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1660 list_move(&rq->queuelist, &next->queuelist);
1661 rq_set_fifo_time(rq, rq_fifo_time(next));
1664 if (cfqq->next_rq == next)
1666 cfq_remove_request(next);
1667 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1668 rq_data_dir(next), rq_is_sync(next));
1671 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1674 struct cfq_data *cfqd = q->elevator->elevator_data;
1675 struct cfq_io_context *cic;
1676 struct cfq_queue *cfqq;
1679 * Disallow merge of a sync bio into an async request.
1681 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1685 * Lookup the cfqq that this bio will be queued with and allow
1686 * merge only if rq is queued there. This function can be called
1687 * from plug merge without queue_lock. In such cases, ioc of @rq
1688 * and %current are guaranteed to be equal. Avoid lookup which
1689 * requires queue_lock by using @rq's cic.
1691 if (current->io_context == RQ_CIC(rq)->ioc) {
1694 cic = cfq_cic_lookup(cfqd, current->io_context);
1699 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1700 return cfqq == RQ_CFQQ(rq);
1703 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1705 del_timer(&cfqd->idle_slice_timer);
1706 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1709 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1710 struct cfq_queue *cfqq)
1713 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1714 cfqd->serving_prio, cfqd->serving_type);
1715 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1716 cfqq->slice_start = 0;
1717 cfqq->dispatch_start = jiffies;
1718 cfqq->allocated_slice = 0;
1719 cfqq->slice_end = 0;
1720 cfqq->slice_dispatch = 0;
1721 cfqq->nr_sectors = 0;
1723 cfq_clear_cfqq_wait_request(cfqq);
1724 cfq_clear_cfqq_must_dispatch(cfqq);
1725 cfq_clear_cfqq_must_alloc_slice(cfqq);
1726 cfq_clear_cfqq_fifo_expire(cfqq);
1727 cfq_mark_cfqq_slice_new(cfqq);
1729 cfq_del_timer(cfqd, cfqq);
1732 cfqd->active_queue = cfqq;
1736 * current cfqq expired its slice (or was too idle), select new one
1739 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1742 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1744 if (cfq_cfqq_wait_request(cfqq))
1745 cfq_del_timer(cfqd, cfqq);
1747 cfq_clear_cfqq_wait_request(cfqq);
1748 cfq_clear_cfqq_wait_busy(cfqq);
1751 * If this cfqq is shared between multiple processes, check to
1752 * make sure that those processes are still issuing I/Os within
1753 * the mean seek distance. If not, it may be time to break the
1754 * queues apart again.
1756 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1757 cfq_mark_cfqq_split_coop(cfqq);
1760 * store what was left of this slice, if the queue idled/timed out
1763 if (cfq_cfqq_slice_new(cfqq))
1764 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1766 cfqq->slice_resid = cfqq->slice_end - jiffies;
1767 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1770 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1772 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1773 cfq_del_cfqq_rr(cfqd, cfqq);
1775 cfq_resort_rr_list(cfqd, cfqq);
1777 if (cfqq == cfqd->active_queue)
1778 cfqd->active_queue = NULL;
1780 if (cfqd->active_cic) {
1781 put_io_context(cfqd->active_cic->ioc);
1782 cfqd->active_cic = NULL;
1786 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1788 struct cfq_queue *cfqq = cfqd->active_queue;
1791 __cfq_slice_expired(cfqd, cfqq, timed_out);
1795 * Get next queue for service. Unless we have a queue preemption,
1796 * we'll simply select the first cfqq in the service tree.
1798 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1800 struct cfq_rb_root *service_tree =
1801 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1802 cfqd->serving_type);
1804 if (!cfqd->rq_queued)
1807 /* There is nothing to dispatch */
1810 if (RB_EMPTY_ROOT(&service_tree->rb))
1812 return cfq_rb_first(service_tree);
1815 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1817 struct cfq_group *cfqg;
1818 struct cfq_queue *cfqq;
1820 struct cfq_rb_root *st;
1822 if (!cfqd->rq_queued)
1825 cfqg = cfq_get_next_cfqg(cfqd);
1829 for_each_cfqg_st(cfqg, i, j, st)
1830 if ((cfqq = cfq_rb_first(st)) != NULL)
1836 * Get and set a new active queue for service.
1838 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1839 struct cfq_queue *cfqq)
1842 cfqq = cfq_get_next_queue(cfqd);
1844 __cfq_set_active_queue(cfqd, cfqq);
1848 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1851 if (blk_rq_pos(rq) >= cfqd->last_position)
1852 return blk_rq_pos(rq) - cfqd->last_position;
1854 return cfqd->last_position - blk_rq_pos(rq);
1857 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1860 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1863 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1864 struct cfq_queue *cur_cfqq)
1866 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1867 struct rb_node *parent, *node;
1868 struct cfq_queue *__cfqq;
1869 sector_t sector = cfqd->last_position;
1871 if (RB_EMPTY_ROOT(root))
1875 * First, if we find a request starting at the end of the last
1876 * request, choose it.
1878 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1883 * If the exact sector wasn't found, the parent of the NULL leaf
1884 * will contain the closest sector.
1886 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1887 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1890 if (blk_rq_pos(__cfqq->next_rq) < sector)
1891 node = rb_next(&__cfqq->p_node);
1893 node = rb_prev(&__cfqq->p_node);
1897 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1898 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1906 * cur_cfqq - passed in so that we don't decide that the current queue is
1907 * closely cooperating with itself.
1909 * So, basically we're assuming that that cur_cfqq has dispatched at least
1910 * one request, and that cfqd->last_position reflects a position on the disk
1911 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1914 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1915 struct cfq_queue *cur_cfqq)
1917 struct cfq_queue *cfqq;
1919 if (cfq_class_idle(cur_cfqq))
1921 if (!cfq_cfqq_sync(cur_cfqq))
1923 if (CFQQ_SEEKY(cur_cfqq))
1927 * Don't search priority tree if it's the only queue in the group.
1929 if (cur_cfqq->cfqg->nr_cfqq == 1)
1933 * We should notice if some of the queues are cooperating, eg
1934 * working closely on the same area of the disk. In that case,
1935 * we can group them together and don't waste time idling.
1937 cfqq = cfqq_close(cfqd, cur_cfqq);
1941 /* If new queue belongs to different cfq_group, don't choose it */
1942 if (cur_cfqq->cfqg != cfqq->cfqg)
1946 * It only makes sense to merge sync queues.
1948 if (!cfq_cfqq_sync(cfqq))
1950 if (CFQQ_SEEKY(cfqq))
1954 * Do not merge queues of different priority classes
1956 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1963 * Determine whether we should enforce idle window for this queue.
1966 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1968 enum wl_prio_t prio = cfqq_prio(cfqq);
1969 struct cfq_rb_root *service_tree = cfqq->service_tree;
1971 BUG_ON(!service_tree);
1972 BUG_ON(!service_tree->count);
1974 if (!cfqd->cfq_slice_idle)
1977 /* We never do for idle class queues. */
1978 if (prio == IDLE_WORKLOAD)
1981 /* We do for queues that were marked with idle window flag. */
1982 if (cfq_cfqq_idle_window(cfqq) &&
1983 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1987 * Otherwise, we do only if they are the last ones
1988 * in their service tree.
1990 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
1991 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
1993 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1994 service_tree->count);
1998 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2000 struct cfq_queue *cfqq = cfqd->active_queue;
2001 struct cfq_io_context *cic;
2002 unsigned long sl, group_idle = 0;
2005 * SSD device without seek penalty, disable idling. But only do so
2006 * for devices that support queuing, otherwise we still have a problem
2007 * with sync vs async workloads.
2009 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2012 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2013 WARN_ON(cfq_cfqq_slice_new(cfqq));
2016 * idle is disabled, either manually or by past process history
2018 if (!cfq_should_idle(cfqd, cfqq)) {
2019 /* no queue idling. Check for group idling */
2020 if (cfqd->cfq_group_idle)
2021 group_idle = cfqd->cfq_group_idle;
2027 * still active requests from this queue, don't idle
2029 if (cfqq->dispatched)
2033 * task has exited, don't wait
2035 cic = cfqd->active_cic;
2036 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
2040 * If our average think time is larger than the remaining time
2041 * slice, then don't idle. This avoids overrunning the allotted
2044 if (sample_valid(cic->ttime.ttime_samples) &&
2045 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2046 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2047 cic->ttime.ttime_mean);
2051 /* There are other queues in the group, don't do group idle */
2052 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2055 cfq_mark_cfqq_wait_request(cfqq);
2058 sl = cfqd->cfq_group_idle;
2060 sl = cfqd->cfq_slice_idle;
2062 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2063 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
2064 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2065 group_idle ? 1 : 0);
2069 * Move request from internal lists to the request queue dispatch list.
2071 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2073 struct cfq_data *cfqd = q->elevator->elevator_data;
2074 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2076 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2078 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2079 cfq_remove_request(rq);
2081 (RQ_CFQG(rq))->dispatched++;
2082 elv_dispatch_sort(q, rq);
2084 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2085 cfqq->nr_sectors += blk_rq_sectors(rq);
2086 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2087 rq_data_dir(rq), rq_is_sync(rq));
2091 * return expired entry, or NULL to just start from scratch in rbtree
2093 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2095 struct request *rq = NULL;
2097 if (cfq_cfqq_fifo_expire(cfqq))
2100 cfq_mark_cfqq_fifo_expire(cfqq);
2102 if (list_empty(&cfqq->fifo))
2105 rq = rq_entry_fifo(cfqq->fifo.next);
2106 if (time_before(jiffies, rq_fifo_time(rq)))
2109 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2114 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2116 const int base_rq = cfqd->cfq_slice_async_rq;
2118 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2120 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2124 * Must be called with the queue_lock held.
2126 static int cfqq_process_refs(struct cfq_queue *cfqq)
2128 int process_refs, io_refs;
2130 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2131 process_refs = cfqq->ref - io_refs;
2132 BUG_ON(process_refs < 0);
2133 return process_refs;
2136 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2138 int process_refs, new_process_refs;
2139 struct cfq_queue *__cfqq;
2142 * If there are no process references on the new_cfqq, then it is
2143 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2144 * chain may have dropped their last reference (not just their
2145 * last process reference).
2147 if (!cfqq_process_refs(new_cfqq))
2150 /* Avoid a circular list and skip interim queue merges */
2151 while ((__cfqq = new_cfqq->new_cfqq)) {
2157 process_refs = cfqq_process_refs(cfqq);
2158 new_process_refs = cfqq_process_refs(new_cfqq);
2160 * If the process for the cfqq has gone away, there is no
2161 * sense in merging the queues.
2163 if (process_refs == 0 || new_process_refs == 0)
2167 * Merge in the direction of the lesser amount of work.
2169 if (new_process_refs >= process_refs) {
2170 cfqq->new_cfqq = new_cfqq;
2171 new_cfqq->ref += process_refs;
2173 new_cfqq->new_cfqq = cfqq;
2174 cfqq->ref += new_process_refs;
2178 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2179 struct cfq_group *cfqg, enum wl_prio_t prio)
2181 struct cfq_queue *queue;
2183 bool key_valid = false;
2184 unsigned long lowest_key = 0;
2185 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2187 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2188 /* select the one with lowest rb_key */
2189 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2191 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2192 lowest_key = queue->rb_key;
2201 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2205 struct cfq_rb_root *st;
2206 unsigned group_slice;
2207 enum wl_prio_t original_prio = cfqd->serving_prio;
2209 /* Choose next priority. RT > BE > IDLE */
2210 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2211 cfqd->serving_prio = RT_WORKLOAD;
2212 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2213 cfqd->serving_prio = BE_WORKLOAD;
2215 cfqd->serving_prio = IDLE_WORKLOAD;
2216 cfqd->workload_expires = jiffies + 1;
2220 if (original_prio != cfqd->serving_prio)
2224 * For RT and BE, we have to choose also the type
2225 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2228 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2232 * check workload expiration, and that we still have other queues ready
2234 if (count && !time_after(jiffies, cfqd->workload_expires))
2238 /* otherwise select new workload type */
2239 cfqd->serving_type =
2240 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2241 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2245 * the workload slice is computed as a fraction of target latency
2246 * proportional to the number of queues in that workload, over
2247 * all the queues in the same priority class
2249 group_slice = cfq_group_slice(cfqd, cfqg);
2251 slice = group_slice * count /
2252 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2253 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2255 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2259 * Async queues are currently system wide. Just taking
2260 * proportion of queues with-in same group will lead to higher
2261 * async ratio system wide as generally root group is going
2262 * to have higher weight. A more accurate thing would be to
2263 * calculate system wide asnc/sync ratio.
2265 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2266 tmp = tmp/cfqd->busy_queues;
2267 slice = min_t(unsigned, slice, tmp);
2269 /* async workload slice is scaled down according to
2270 * the sync/async slice ratio. */
2271 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2273 /* sync workload slice is at least 2 * cfq_slice_idle */
2274 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2276 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2277 cfq_log(cfqd, "workload slice:%d", slice);
2278 cfqd->workload_expires = jiffies + slice;
2281 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2283 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2284 struct cfq_group *cfqg;
2286 if (RB_EMPTY_ROOT(&st->rb))
2288 cfqg = cfq_rb_first_group(st);
2289 update_min_vdisktime(st);
2293 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2295 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2297 cfqd->serving_group = cfqg;
2299 /* Restore the workload type data */
2300 if (cfqg->saved_workload_slice) {
2301 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2302 cfqd->serving_type = cfqg->saved_workload;
2303 cfqd->serving_prio = cfqg->saved_serving_prio;
2305 cfqd->workload_expires = jiffies - 1;
2307 choose_service_tree(cfqd, cfqg);
2311 * Select a queue for service. If we have a current active queue,
2312 * check whether to continue servicing it, or retrieve and set a new one.
2314 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2316 struct cfq_queue *cfqq, *new_cfqq = NULL;
2318 cfqq = cfqd->active_queue;
2322 if (!cfqd->rq_queued)
2326 * We were waiting for group to get backlogged. Expire the queue
2328 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2332 * The active queue has run out of time, expire it and select new.
2334 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2336 * If slice had not expired at the completion of last request
2337 * we might not have turned on wait_busy flag. Don't expire
2338 * the queue yet. Allow the group to get backlogged.
2340 * The very fact that we have used the slice, that means we
2341 * have been idling all along on this queue and it should be
2342 * ok to wait for this request to complete.
2344 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2345 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2349 goto check_group_idle;
2353 * The active queue has requests and isn't expired, allow it to
2356 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2360 * If another queue has a request waiting within our mean seek
2361 * distance, let it run. The expire code will check for close
2362 * cooperators and put the close queue at the front of the service
2363 * tree. If possible, merge the expiring queue with the new cfqq.
2365 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2367 if (!cfqq->new_cfqq)
2368 cfq_setup_merge(cfqq, new_cfqq);
2373 * No requests pending. If the active queue still has requests in
2374 * flight or is idling for a new request, allow either of these
2375 * conditions to happen (or time out) before selecting a new queue.
2377 if (timer_pending(&cfqd->idle_slice_timer)) {
2383 * This is a deep seek queue, but the device is much faster than
2384 * the queue can deliver, don't idle
2386 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2387 (cfq_cfqq_slice_new(cfqq) ||
2388 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2389 cfq_clear_cfqq_deep(cfqq);
2390 cfq_clear_cfqq_idle_window(cfqq);
2393 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2399 * If group idle is enabled and there are requests dispatched from
2400 * this group, wait for requests to complete.
2403 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2404 cfqq->cfqg->dispatched &&
2405 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2411 cfq_slice_expired(cfqd, 0);
2414 * Current queue expired. Check if we have to switch to a new
2418 cfq_choose_cfqg(cfqd);
2420 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2425 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2429 while (cfqq->next_rq) {
2430 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2434 BUG_ON(!list_empty(&cfqq->fifo));
2436 /* By default cfqq is not expired if it is empty. Do it explicitly */
2437 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2442 * Drain our current requests. Used for barriers and when switching
2443 * io schedulers on-the-fly.
2445 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2447 struct cfq_queue *cfqq;
2450 /* Expire the timeslice of the current active queue first */
2451 cfq_slice_expired(cfqd, 0);
2452 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2453 __cfq_set_active_queue(cfqd, cfqq);
2454 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2457 BUG_ON(cfqd->busy_queues);
2459 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2463 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2464 struct cfq_queue *cfqq)
2466 /* the queue hasn't finished any request, can't estimate */
2467 if (cfq_cfqq_slice_new(cfqq))
2469 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2476 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2478 unsigned int max_dispatch;
2481 * Drain async requests before we start sync IO
2483 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2487 * If this is an async queue and we have sync IO in flight, let it wait
2489 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2492 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2493 if (cfq_class_idle(cfqq))
2497 * Does this cfqq already have too much IO in flight?
2499 if (cfqq->dispatched >= max_dispatch) {
2500 bool promote_sync = false;
2502 * idle queue must always only have a single IO in flight
2504 if (cfq_class_idle(cfqq))
2508 * If there is only one sync queue
2509 * we can ignore async queue here and give the sync
2510 * queue no dispatch limit. The reason is a sync queue can
2511 * preempt async queue, limiting the sync queue doesn't make
2512 * sense. This is useful for aiostress test.
2514 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2515 promote_sync = true;
2518 * We have other queues, don't allow more IO from this one
2520 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2525 * Sole queue user, no limit
2527 if (cfqd->busy_queues == 1 || promote_sync)
2531 * Normally we start throttling cfqq when cfq_quantum/2
2532 * requests have been dispatched. But we can drive
2533 * deeper queue depths at the beginning of slice
2534 * subjected to upper limit of cfq_quantum.
2536 max_dispatch = cfqd->cfq_quantum;
2540 * Async queues must wait a bit before being allowed dispatch.
2541 * We also ramp up the dispatch depth gradually for async IO,
2542 * based on the last sync IO we serviced
2544 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2545 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2548 depth = last_sync / cfqd->cfq_slice[1];
2549 if (!depth && !cfqq->dispatched)
2551 if (depth < max_dispatch)
2552 max_dispatch = depth;
2556 * If we're below the current max, allow a dispatch
2558 return cfqq->dispatched < max_dispatch;
2562 * Dispatch a request from cfqq, moving them to the request queue
2565 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2569 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2571 if (!cfq_may_dispatch(cfqd, cfqq))
2575 * follow expired path, else get first next available
2577 rq = cfq_check_fifo(cfqq);
2582 * insert request into driver dispatch list
2584 cfq_dispatch_insert(cfqd->queue, rq);
2586 if (!cfqd->active_cic) {
2587 struct cfq_io_context *cic = RQ_CIC(rq);
2589 atomic_long_inc(&cic->ioc->refcount);
2590 cfqd->active_cic = cic;
2597 * Find the cfqq that we need to service and move a request from that to the
2600 static int cfq_dispatch_requests(struct request_queue *q, int force)
2602 struct cfq_data *cfqd = q->elevator->elevator_data;
2603 struct cfq_queue *cfqq;
2605 if (!cfqd->busy_queues)
2608 if (unlikely(force))
2609 return cfq_forced_dispatch(cfqd);
2611 cfqq = cfq_select_queue(cfqd);
2616 * Dispatch a request from this cfqq, if it is allowed
2618 if (!cfq_dispatch_request(cfqd, cfqq))
2621 cfqq->slice_dispatch++;
2622 cfq_clear_cfqq_must_dispatch(cfqq);
2625 * expire an async queue immediately if it has used up its slice. idle
2626 * queue always expire after 1 dispatch round.
2628 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2629 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2630 cfq_class_idle(cfqq))) {
2631 cfqq->slice_end = jiffies + 1;
2632 cfq_slice_expired(cfqd, 0);
2635 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2640 * task holds one reference to the queue, dropped when task exits. each rq
2641 * in-flight on this queue also holds a reference, dropped when rq is freed.
2643 * Each cfq queue took a reference on the parent group. Drop it now.
2644 * queue lock must be held here.
2646 static void cfq_put_queue(struct cfq_queue *cfqq)
2648 struct cfq_data *cfqd = cfqq->cfqd;
2649 struct cfq_group *cfqg;
2651 BUG_ON(cfqq->ref <= 0);
2657 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2658 BUG_ON(rb_first(&cfqq->sort_list));
2659 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2662 if (unlikely(cfqd->active_queue == cfqq)) {
2663 __cfq_slice_expired(cfqd, cfqq, 0);
2664 cfq_schedule_dispatch(cfqd);
2667 BUG_ON(cfq_cfqq_on_rr(cfqq));
2668 kmem_cache_free(cfq_pool, cfqq);
2673 * Call func for each cic attached to this ioc.
2676 call_for_each_cic(struct io_context *ioc,
2677 void (*func)(struct io_context *, struct cfq_io_context *))
2679 struct cfq_io_context *cic;
2680 struct hlist_node *n;
2684 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2690 static void cfq_cic_free_rcu(struct rcu_head *head)
2692 struct cfq_io_context *cic;
2694 cic = container_of(head, struct cfq_io_context, rcu_head);
2696 kmem_cache_free(cfq_ioc_pool, cic);
2697 elv_ioc_count_dec(cfq_ioc_count);
2701 * CFQ scheduler is exiting, grab exit lock and check
2702 * the pending io context count. If it hits zero,
2703 * complete ioc_gone and set it back to NULL
2705 spin_lock(&ioc_gone_lock);
2706 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2710 spin_unlock(&ioc_gone_lock);
2714 static void cfq_cic_free(struct cfq_io_context *cic)
2716 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2719 static void cfq_release_cic(struct cfq_io_context *cic)
2721 struct io_context *ioc = cic->ioc;
2722 unsigned long dead_key = (unsigned long) cic->key;
2724 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2725 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2726 hlist_del_rcu(&cic->cic_list);
2730 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2732 unsigned long flags;
2734 spin_lock_irqsave(&ioc->lock, flags);
2735 cfq_release_cic(cic);
2736 spin_unlock_irqrestore(&ioc->lock, flags);
2740 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2741 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2742 * and ->trim() which is called with the task lock held
2744 static void cfq_free_io_context(struct io_context *ioc)
2747 * ioc->refcount is zero here, or we are called from elv_unregister(),
2748 * so no more cic's are allowed to be linked into this ioc. So it
2749 * should be ok to iterate over the known list, we will see all cic's
2750 * since no new ones are added.
2752 call_for_each_cic(ioc, cic_free_func);
2755 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2757 struct cfq_queue *__cfqq, *next;
2760 * If this queue was scheduled to merge with another queue, be
2761 * sure to drop the reference taken on that queue (and others in
2762 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2764 __cfqq = cfqq->new_cfqq;
2766 if (__cfqq == cfqq) {
2767 WARN(1, "cfqq->new_cfqq loop detected\n");
2770 next = __cfqq->new_cfqq;
2771 cfq_put_queue(__cfqq);
2776 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2778 if (unlikely(cfqq == cfqd->active_queue)) {
2779 __cfq_slice_expired(cfqd, cfqq, 0);
2780 cfq_schedule_dispatch(cfqd);
2783 cfq_put_cooperator(cfqq);
2785 cfq_put_queue(cfqq);
2788 static void cfq_exit_cic(struct cfq_io_context *cic)
2790 struct cfq_data *cfqd = cic_to_cfqd(cic);
2791 struct io_context *ioc = cic->ioc;
2793 list_del_init(&cic->queue_list);
2794 cic->key = cfqd_dead_key(cfqd);
2797 * Both setting lookup hint to and clearing it from @cic are done
2798 * under queue_lock. If it's not pointing to @cic now, it never
2799 * will. Hint assignment itself can race safely.
2801 if (rcu_dereference_raw(ioc->ioc_data) == cic)
2802 rcu_assign_pointer(ioc->ioc_data, NULL);
2804 if (cic->cfqq[BLK_RW_ASYNC]) {
2805 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2806 cic->cfqq[BLK_RW_ASYNC] = NULL;
2809 if (cic->cfqq[BLK_RW_SYNC]) {
2810 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2811 cic->cfqq[BLK_RW_SYNC] = NULL;
2815 static void cfq_exit_single_io_context(struct io_context *ioc,
2816 struct cfq_io_context *cic)
2818 struct cfq_data *cfqd = cic_to_cfqd(cic);
2821 struct request_queue *q = cfqd->queue;
2822 unsigned long flags;
2824 spin_lock_irqsave(q->queue_lock, flags);
2827 * Ensure we get a fresh copy of the ->key to prevent
2828 * race between exiting task and queue
2830 smp_read_barrier_depends();
2831 if (cic->key == cfqd)
2834 spin_unlock_irqrestore(q->queue_lock, flags);
2839 * The process that ioc belongs to has exited, we need to clean up
2840 * and put the internal structures we have that belongs to that process.
2842 static void cfq_exit_io_context(struct io_context *ioc)
2844 call_for_each_cic(ioc, cfq_exit_single_io_context);
2847 static struct cfq_io_context *
2848 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2850 struct cfq_io_context *cic;
2852 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2855 cic->ttime.last_end_request = jiffies;
2856 INIT_LIST_HEAD(&cic->queue_list);
2857 INIT_HLIST_NODE(&cic->cic_list);
2858 cic->dtor = cfq_free_io_context;
2859 cic->exit = cfq_exit_io_context;
2860 elv_ioc_count_inc(cfq_ioc_count);
2866 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2868 struct task_struct *tsk = current;
2871 if (!cfq_cfqq_prio_changed(cfqq))
2874 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2875 switch (ioprio_class) {
2877 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2878 case IOPRIO_CLASS_NONE:
2880 * no prio set, inherit CPU scheduling settings
2882 cfqq->ioprio = task_nice_ioprio(tsk);
2883 cfqq->ioprio_class = task_nice_ioclass(tsk);
2885 case IOPRIO_CLASS_RT:
2886 cfqq->ioprio = task_ioprio(ioc);
2887 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2889 case IOPRIO_CLASS_BE:
2890 cfqq->ioprio = task_ioprio(ioc);
2891 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2893 case IOPRIO_CLASS_IDLE:
2894 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2896 cfq_clear_cfqq_idle_window(cfqq);
2901 * keep track of original prio settings in case we have to temporarily
2902 * elevate the priority of this queue
2904 cfqq->org_ioprio = cfqq->ioprio;
2905 cfq_clear_cfqq_prio_changed(cfqq);
2908 static void changed_ioprio(struct cfq_io_context *cic)
2910 struct cfq_data *cfqd = cic_to_cfqd(cic);
2911 struct cfq_queue *cfqq;
2913 if (unlikely(!cfqd))
2916 cfqq = cic->cfqq[BLK_RW_ASYNC];
2918 struct cfq_queue *new_cfqq;
2919 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2922 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2923 cfq_put_queue(cfqq);
2927 cfqq = cic->cfqq[BLK_RW_SYNC];
2929 cfq_mark_cfqq_prio_changed(cfqq);
2932 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2933 pid_t pid, bool is_sync)
2935 RB_CLEAR_NODE(&cfqq->rb_node);
2936 RB_CLEAR_NODE(&cfqq->p_node);
2937 INIT_LIST_HEAD(&cfqq->fifo);
2942 cfq_mark_cfqq_prio_changed(cfqq);
2945 if (!cfq_class_idle(cfqq))
2946 cfq_mark_cfqq_idle_window(cfqq);
2947 cfq_mark_cfqq_sync(cfqq);
2952 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2953 static void changed_cgroup(struct cfq_io_context *cic)
2955 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2956 struct cfq_data *cfqd = cic_to_cfqd(cic);
2957 struct request_queue *q;
2959 if (unlikely(!cfqd))
2966 * Drop reference to sync queue. A new sync queue will be
2967 * assigned in new group upon arrival of a fresh request.
2969 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2970 cic_set_cfqq(cic, NULL, 1);
2971 cfq_put_queue(sync_cfqq);
2974 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2976 static struct cfq_queue *
2977 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2978 struct io_context *ioc, gfp_t gfp_mask)
2980 struct cfq_queue *cfqq, *new_cfqq = NULL;
2981 struct cfq_io_context *cic;
2982 struct cfq_group *cfqg;
2985 cfqg = cfq_get_cfqg(cfqd);
2986 cic = cfq_cic_lookup(cfqd, ioc);
2987 /* cic always exists here */
2988 cfqq = cic_to_cfqq(cic, is_sync);
2991 * Always try a new alloc if we fell back to the OOM cfqq
2992 * originally, since it should just be a temporary situation.
2994 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2999 } else if (gfp_mask & __GFP_WAIT) {
3000 spin_unlock_irq(cfqd->queue->queue_lock);
3001 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3002 gfp_mask | __GFP_ZERO,
3004 spin_lock_irq(cfqd->queue->queue_lock);
3008 cfqq = kmem_cache_alloc_node(cfq_pool,
3009 gfp_mask | __GFP_ZERO,
3014 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3015 cfq_init_prio_data(cfqq, ioc);
3016 cfq_link_cfqq_cfqg(cfqq, cfqg);
3017 cfq_log_cfqq(cfqd, cfqq, "alloced");
3019 cfqq = &cfqd->oom_cfqq;
3023 kmem_cache_free(cfq_pool, new_cfqq);
3028 static struct cfq_queue **
3029 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3031 switch (ioprio_class) {
3032 case IOPRIO_CLASS_RT:
3033 return &cfqd->async_cfqq[0][ioprio];
3034 case IOPRIO_CLASS_BE:
3035 return &cfqd->async_cfqq[1][ioprio];
3036 case IOPRIO_CLASS_IDLE:
3037 return &cfqd->async_idle_cfqq;
3043 static struct cfq_queue *
3044 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
3047 const int ioprio = task_ioprio(ioc);
3048 const int ioprio_class = task_ioprio_class(ioc);
3049 struct cfq_queue **async_cfqq = NULL;
3050 struct cfq_queue *cfqq = NULL;
3053 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3058 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
3061 * pin the queue now that it's allocated, scheduler exit will prune it
3063 if (!is_sync && !(*async_cfqq)) {
3073 * We drop cfq io contexts lazily, so we may find a dead one.
3076 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3077 struct cfq_io_context *cic)
3079 unsigned long flags;
3081 WARN_ON(!list_empty(&cic->queue_list));
3082 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3084 spin_lock_irqsave(&ioc->lock, flags);
3086 BUG_ON(rcu_dereference_check(ioc->ioc_data,
3087 lockdep_is_held(&ioc->lock)) == cic);
3089 radix_tree_delete(&ioc->radix_root, cfqd->queue->id);
3090 hlist_del_rcu(&cic->cic_list);
3091 spin_unlock_irqrestore(&ioc->lock, flags);
3097 * cfq_cic_lookup - lookup cfq_io_context
3098 * @cfqd: the associated cfq_data
3099 * @ioc: the associated io_context
3101 * Look up cfq_io_context associated with @cfqd - @ioc pair. Must be
3102 * called with queue_lock held.
3104 static struct cfq_io_context *
3105 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3107 struct cfq_io_context *cic;
3109 lockdep_assert_held(cfqd->queue->queue_lock);
3116 * we maintain a last-hit cache, to avoid browsing over the tree
3118 cic = rcu_dereference(ioc->ioc_data);
3119 if (cic && cic->key == cfqd)
3123 cic = radix_tree_lookup(&ioc->radix_root, cfqd->queue->id);
3126 if (likely(cic->key == cfqd)) {
3127 /* hint assignment itself can race safely */
3128 rcu_assign_pointer(ioc->ioc_data, cic);
3131 cfq_drop_dead_cic(cfqd, ioc, cic);
3139 * cfq_create_cic - create and link a cfq_io_context
3140 * @cfqd: cfqd of interest
3141 * @gfp_mask: allocation mask
3143 * Make sure cfq_io_context linking %current->io_context and @cfqd exists.
3144 * If ioc and/or cic doesn't exist, they will be created using @gfp_mask.
3146 static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
3148 struct request_queue *q = cfqd->queue;
3149 struct cfq_io_context *cic = NULL;
3150 struct io_context *ioc;
3153 might_sleep_if(gfp_mask & __GFP_WAIT);
3155 /* allocate stuff */
3156 ioc = current_io_context(gfp_mask, q->node);
3160 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3164 ret = radix_tree_preload(gfp_mask);
3170 cic->q = cfqd->queue;
3172 /* lock both q and ioc and try to link @cic */
3173 spin_lock_irq(q->queue_lock);
3174 spin_lock(&ioc->lock);
3176 ret = radix_tree_insert(&ioc->radix_root, q->id, cic);
3178 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3179 list_add(&cic->queue_list, &cfqd->cic_list);
3181 } else if (ret == -EEXIST) {
3182 /* someone else already did it */
3186 spin_unlock(&ioc->lock);
3187 spin_unlock_irq(q->queue_lock);
3189 radix_tree_preload_end();
3192 printk(KERN_ERR "cfq: cic link failed!\n");
3199 * cfq_get_io_context - acquire cfq_io_context and bump refcnt on io_context
3200 * @cfqd: cfqd to setup cic for
3201 * @gfp_mask: allocation mask
3203 * Return cfq_io_context associating @cfqd and %current->io_context and
3204 * bump refcnt on io_context. If ioc or cic doesn't exist, they're created
3207 * Must be called under queue_lock which may be released and re-acquired.
3208 * This function also may sleep depending on @gfp_mask.
3210 static struct cfq_io_context *
3211 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3213 struct request_queue *q = cfqd->queue;
3214 struct cfq_io_context *cic = NULL;
3215 struct io_context *ioc;
3218 lockdep_assert_held(q->queue_lock);
3222 ioc = current->io_context;
3224 cic = cfq_cic_lookup(cfqd, ioc);
3229 /* slow path - unlock, create missing ones and retry */
3230 spin_unlock_irq(q->queue_lock);
3231 err = cfq_create_cic(cfqd, gfp_mask);
3232 spin_lock_irq(q->queue_lock);
3237 /* bump @ioc's refcnt and handle changed notifications */
3238 get_io_context(ioc);
3240 if (unlikely(cic->changed)) {
3241 if (test_and_clear_bit(CIC_IOPRIO_CHANGED, &cic->changed))
3242 changed_ioprio(cic);
3243 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3244 if (test_and_clear_bit(CIC_CGROUP_CHANGED, &cic->changed))
3245 changed_cgroup(cic);
3253 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3255 unsigned long elapsed = jiffies - ttime->last_end_request;
3256 elapsed = min(elapsed, 2UL * slice_idle);
3258 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3259 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3260 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3264 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3265 struct cfq_io_context *cic)
3267 if (cfq_cfqq_sync(cfqq)) {
3268 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3269 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3270 cfqd->cfq_slice_idle);
3272 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3273 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3278 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3282 sector_t n_sec = blk_rq_sectors(rq);
3283 if (cfqq->last_request_pos) {
3284 if (cfqq->last_request_pos < blk_rq_pos(rq))
3285 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3287 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3290 cfqq->seek_history <<= 1;
3291 if (blk_queue_nonrot(cfqd->queue))
3292 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3294 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3298 * Disable idle window if the process thinks too long or seeks so much that
3302 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3303 struct cfq_io_context *cic)
3305 int old_idle, enable_idle;
3308 * Don't idle for async or idle io prio class
3310 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3313 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3315 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3316 cfq_mark_cfqq_deep(cfqq);
3318 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3320 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3321 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3323 else if (sample_valid(cic->ttime.ttime_samples)) {
3324 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3330 if (old_idle != enable_idle) {
3331 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3333 cfq_mark_cfqq_idle_window(cfqq);
3335 cfq_clear_cfqq_idle_window(cfqq);
3340 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3341 * no or if we aren't sure, a 1 will cause a preempt.
3344 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3347 struct cfq_queue *cfqq;
3349 cfqq = cfqd->active_queue;
3353 if (cfq_class_idle(new_cfqq))
3356 if (cfq_class_idle(cfqq))
3360 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3362 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3366 * if the new request is sync, but the currently running queue is
3367 * not, let the sync request have priority.
3369 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3372 if (new_cfqq->cfqg != cfqq->cfqg)
3375 if (cfq_slice_used(cfqq))
3378 /* Allow preemption only if we are idling on sync-noidle tree */
3379 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3380 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3381 new_cfqq->service_tree->count == 2 &&
3382 RB_EMPTY_ROOT(&cfqq->sort_list))
3386 * So both queues are sync. Let the new request get disk time if
3387 * it's a metadata request and the current queue is doing regular IO.
3389 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3393 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3395 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3398 /* An idle queue should not be idle now for some reason */
3399 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3402 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3406 * if this request is as-good as one we would expect from the
3407 * current cfqq, let it preempt
3409 if (cfq_rq_close(cfqd, cfqq, rq))
3416 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3417 * let it have half of its nominal slice.
3419 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3421 struct cfq_queue *old_cfqq = cfqd->active_queue;
3423 cfq_log_cfqq(cfqd, cfqq, "preempt");
3424 cfq_slice_expired(cfqd, 1);
3427 * workload type is changed, don't save slice, otherwise preempt
3430 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3431 cfqq->cfqg->saved_workload_slice = 0;
3434 * Put the new queue at the front of the of the current list,
3435 * so we know that it will be selected next.
3437 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3439 cfq_service_tree_add(cfqd, cfqq, 1);
3441 cfqq->slice_end = 0;
3442 cfq_mark_cfqq_slice_new(cfqq);
3446 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3447 * something we should do about it
3450 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3453 struct cfq_io_context *cic = RQ_CIC(rq);
3456 if (rq->cmd_flags & REQ_PRIO)
3457 cfqq->prio_pending++;
3459 cfq_update_io_thinktime(cfqd, cfqq, cic);
3460 cfq_update_io_seektime(cfqd, cfqq, rq);
3461 cfq_update_idle_window(cfqd, cfqq, cic);
3463 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3465 if (cfqq == cfqd->active_queue) {
3467 * Remember that we saw a request from this process, but
3468 * don't start queuing just yet. Otherwise we risk seeing lots
3469 * of tiny requests, because we disrupt the normal plugging
3470 * and merging. If the request is already larger than a single
3471 * page, let it rip immediately. For that case we assume that
3472 * merging is already done. Ditto for a busy system that
3473 * has other work pending, don't risk delaying until the
3474 * idle timer unplug to continue working.
3476 if (cfq_cfqq_wait_request(cfqq)) {
3477 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3478 cfqd->busy_queues > 1) {
3479 cfq_del_timer(cfqd, cfqq);
3480 cfq_clear_cfqq_wait_request(cfqq);
3481 __blk_run_queue(cfqd->queue);
3483 cfq_blkiocg_update_idle_time_stats(
3485 cfq_mark_cfqq_must_dispatch(cfqq);
3488 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3490 * not the active queue - expire current slice if it is
3491 * idle and has expired it's mean thinktime or this new queue
3492 * has some old slice time left and is of higher priority or
3493 * this new queue is RT and the current one is BE
3495 cfq_preempt_queue(cfqd, cfqq);
3496 __blk_run_queue(cfqd->queue);
3500 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3502 struct cfq_data *cfqd = q->elevator->elevator_data;
3503 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3505 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3506 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3508 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3509 list_add_tail(&rq->queuelist, &cfqq->fifo);
3511 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3512 &cfqd->serving_group->blkg, rq_data_dir(rq),
3514 cfq_rq_enqueued(cfqd, cfqq, rq);
3518 * Update hw_tag based on peak queue depth over 50 samples under
3521 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3523 struct cfq_queue *cfqq = cfqd->active_queue;
3525 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3526 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3528 if (cfqd->hw_tag == 1)
3531 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3532 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3536 * If active queue hasn't enough requests and can idle, cfq might not
3537 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3540 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3541 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3542 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3545 if (cfqd->hw_tag_samples++ < 50)
3548 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3554 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3556 struct cfq_io_context *cic = cfqd->active_cic;
3558 /* If the queue already has requests, don't wait */
3559 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3562 /* If there are other queues in the group, don't wait */
3563 if (cfqq->cfqg->nr_cfqq > 1)
3566 /* the only queue in the group, but think time is big */
3567 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3570 if (cfq_slice_used(cfqq))
3573 /* if slice left is less than think time, wait busy */
3574 if (cic && sample_valid(cic->ttime.ttime_samples)
3575 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3579 * If think times is less than a jiffy than ttime_mean=0 and above
3580 * will not be true. It might happen that slice has not expired yet
3581 * but will expire soon (4-5 ns) during select_queue(). To cover the
3582 * case where think time is less than a jiffy, mark the queue wait
3583 * busy if only 1 jiffy is left in the slice.
3585 if (cfqq->slice_end - jiffies == 1)
3591 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3593 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3594 struct cfq_data *cfqd = cfqq->cfqd;
3595 const int sync = rq_is_sync(rq);
3599 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3600 !!(rq->cmd_flags & REQ_NOIDLE));
3602 cfq_update_hw_tag(cfqd);
3604 WARN_ON(!cfqd->rq_in_driver);
3605 WARN_ON(!cfqq->dispatched);
3606 cfqd->rq_in_driver--;
3608 (RQ_CFQG(rq))->dispatched--;
3609 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3610 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3611 rq_data_dir(rq), rq_is_sync(rq));
3613 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3616 struct cfq_rb_root *service_tree;
3618 RQ_CIC(rq)->ttime.last_end_request = now;
3620 if (cfq_cfqq_on_rr(cfqq))
3621 service_tree = cfqq->service_tree;
3623 service_tree = service_tree_for(cfqq->cfqg,
3624 cfqq_prio(cfqq), cfqq_type(cfqq));
3625 service_tree->ttime.last_end_request = now;
3626 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3627 cfqd->last_delayed_sync = now;
3630 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3631 cfqq->cfqg->ttime.last_end_request = now;
3635 * If this is the active queue, check if it needs to be expired,
3636 * or if we want to idle in case it has no pending requests.
3638 if (cfqd->active_queue == cfqq) {
3639 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3641 if (cfq_cfqq_slice_new(cfqq)) {
3642 cfq_set_prio_slice(cfqd, cfqq);
3643 cfq_clear_cfqq_slice_new(cfqq);
3647 * Should we wait for next request to come in before we expire
3650 if (cfq_should_wait_busy(cfqd, cfqq)) {
3651 unsigned long extend_sl = cfqd->cfq_slice_idle;
3652 if (!cfqd->cfq_slice_idle)
3653 extend_sl = cfqd->cfq_group_idle;
3654 cfqq->slice_end = jiffies + extend_sl;
3655 cfq_mark_cfqq_wait_busy(cfqq);
3656 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3660 * Idling is not enabled on:
3662 * - idle-priority queues
3664 * - queues with still some requests queued
3665 * - when there is a close cooperator
3667 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3668 cfq_slice_expired(cfqd, 1);
3669 else if (sync && cfqq_empty &&
3670 !cfq_close_cooperator(cfqd, cfqq)) {
3671 cfq_arm_slice_timer(cfqd);
3675 if (!cfqd->rq_in_driver)
3676 cfq_schedule_dispatch(cfqd);
3679 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3681 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3682 cfq_mark_cfqq_must_alloc_slice(cfqq);
3683 return ELV_MQUEUE_MUST;
3686 return ELV_MQUEUE_MAY;
3689 static int cfq_may_queue(struct request_queue *q, int rw)
3691 struct cfq_data *cfqd = q->elevator->elevator_data;
3692 struct task_struct *tsk = current;
3693 struct cfq_io_context *cic;
3694 struct cfq_queue *cfqq;
3697 * don't force setup of a queue from here, as a call to may_queue
3698 * does not necessarily imply that a request actually will be queued.
3699 * so just lookup a possibly existing queue, or return 'may queue'
3702 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3704 return ELV_MQUEUE_MAY;
3706 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3708 cfq_init_prio_data(cfqq, cic->ioc);
3710 return __cfq_may_queue(cfqq);
3713 return ELV_MQUEUE_MAY;
3717 * queue lock held here
3719 static void cfq_put_request(struct request *rq)
3721 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3724 const int rw = rq_data_dir(rq);
3726 BUG_ON(!cfqq->allocated[rw]);
3727 cfqq->allocated[rw]--;
3729 put_io_context(RQ_CIC(rq)->ioc);
3731 rq->elevator_private[0] = NULL;
3732 rq->elevator_private[1] = NULL;
3734 /* Put down rq reference on cfqg */
3735 cfq_put_cfqg(RQ_CFQG(rq));
3736 rq->elevator_private[2] = NULL;
3738 cfq_put_queue(cfqq);
3742 static struct cfq_queue *
3743 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3744 struct cfq_queue *cfqq)
3746 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3747 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3748 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3749 cfq_put_queue(cfqq);
3750 return cic_to_cfqq(cic, 1);
3754 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3755 * was the last process referring to said cfqq.
3757 static struct cfq_queue *
3758 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3760 if (cfqq_process_refs(cfqq) == 1) {
3761 cfqq->pid = current->pid;
3762 cfq_clear_cfqq_coop(cfqq);
3763 cfq_clear_cfqq_split_coop(cfqq);
3767 cic_set_cfqq(cic, NULL, 1);
3769 cfq_put_cooperator(cfqq);
3771 cfq_put_queue(cfqq);
3775 * Allocate cfq data structures associated with this request.
3778 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3780 struct cfq_data *cfqd = q->elevator->elevator_data;
3781 struct cfq_io_context *cic;
3782 const int rw = rq_data_dir(rq);
3783 const bool is_sync = rq_is_sync(rq);
3784 struct cfq_queue *cfqq;
3786 might_sleep_if(gfp_mask & __GFP_WAIT);
3788 spin_lock_irq(q->queue_lock);
3789 cic = cfq_get_io_context(cfqd, gfp_mask);
3794 cfqq = cic_to_cfqq(cic, is_sync);
3795 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3796 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3797 cic_set_cfqq(cic, cfqq, is_sync);
3800 * If the queue was seeky for too long, break it apart.
3802 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3803 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3804 cfqq = split_cfqq(cic, cfqq);
3810 * Check to see if this queue is scheduled to merge with
3811 * another, closely cooperating queue. The merging of
3812 * queues happens here as it must be done in process context.
3813 * The reference on new_cfqq was taken in merge_cfqqs.
3816 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3819 cfqq->allocated[rw]++;
3822 rq->elevator_private[0] = cic;
3823 rq->elevator_private[1] = cfqq;
3824 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3825 spin_unlock_irq(q->queue_lock);
3829 cfq_schedule_dispatch(cfqd);
3830 spin_unlock_irq(q->queue_lock);
3831 cfq_log(cfqd, "set_request fail");
3835 static void cfq_kick_queue(struct work_struct *work)
3837 struct cfq_data *cfqd =
3838 container_of(work, struct cfq_data, unplug_work);
3839 struct request_queue *q = cfqd->queue;
3841 spin_lock_irq(q->queue_lock);
3842 __blk_run_queue(cfqd->queue);
3843 spin_unlock_irq(q->queue_lock);
3847 * Timer running if the active_queue is currently idling inside its time slice
3849 static void cfq_idle_slice_timer(unsigned long data)
3851 struct cfq_data *cfqd = (struct cfq_data *) data;
3852 struct cfq_queue *cfqq;
3853 unsigned long flags;
3856 cfq_log(cfqd, "idle timer fired");
3858 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3860 cfqq = cfqd->active_queue;
3865 * We saw a request before the queue expired, let it through
3867 if (cfq_cfqq_must_dispatch(cfqq))
3873 if (cfq_slice_used(cfqq))
3877 * only expire and reinvoke request handler, if there are
3878 * other queues with pending requests
3880 if (!cfqd->busy_queues)
3884 * not expired and it has a request pending, let it dispatch
3886 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3890 * Queue depth flag is reset only when the idle didn't succeed
3892 cfq_clear_cfqq_deep(cfqq);
3895 cfq_slice_expired(cfqd, timed_out);
3897 cfq_schedule_dispatch(cfqd);
3899 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3902 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3904 del_timer_sync(&cfqd->idle_slice_timer);
3905 cancel_work_sync(&cfqd->unplug_work);
3908 static void cfq_put_async_queues(struct cfq_data *cfqd)
3912 for (i = 0; i < IOPRIO_BE_NR; i++) {
3913 if (cfqd->async_cfqq[0][i])
3914 cfq_put_queue(cfqd->async_cfqq[0][i]);
3915 if (cfqd->async_cfqq[1][i])
3916 cfq_put_queue(cfqd->async_cfqq[1][i]);
3919 if (cfqd->async_idle_cfqq)
3920 cfq_put_queue(cfqd->async_idle_cfqq);
3923 static void cfq_exit_queue(struct elevator_queue *e)
3925 struct cfq_data *cfqd = e->elevator_data;
3926 struct request_queue *q = cfqd->queue;
3929 cfq_shutdown_timer_wq(cfqd);
3931 spin_lock_irq(q->queue_lock);
3933 if (cfqd->active_queue)
3934 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3936 while (!list_empty(&cfqd->cic_list)) {
3937 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3938 struct cfq_io_context,
3944 cfq_put_async_queues(cfqd);
3945 cfq_release_cfq_groups(cfqd);
3948 * If there are groups which we could not unlink from blkcg list,
3949 * wait for a rcu period for them to be freed.
3951 if (cfqd->nr_blkcg_linked_grps)
3954 spin_unlock_irq(q->queue_lock);
3956 cfq_shutdown_timer_wq(cfqd);
3959 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3960 * Do this wait only if there are other unlinked groups out
3961 * there. This can happen if cgroup deletion path claimed the
3962 * responsibility of cleaning up a group before queue cleanup code
3965 * Do not call synchronize_rcu() unconditionally as there are drivers
3966 * which create/delete request queue hundreds of times during scan/boot
3967 * and synchronize_rcu() can take significant time and slow down boot.
3972 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3973 /* Free up per cpu stats for root group */
3974 free_percpu(cfqd->root_group.blkg.stats_cpu);
3979 static void *cfq_init_queue(struct request_queue *q)
3981 struct cfq_data *cfqd;
3983 struct cfq_group *cfqg;
3984 struct cfq_rb_root *st;
3986 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3990 /* Init root service tree */
3991 cfqd->grp_service_tree = CFQ_RB_ROOT;
3993 /* Init root group */
3994 cfqg = &cfqd->root_group;
3995 for_each_cfqg_st(cfqg, i, j, st)
3997 RB_CLEAR_NODE(&cfqg->rb_node);
3999 /* Give preference to root group over other groups */
4000 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
4002 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4004 * Set root group reference to 2. One reference will be dropped when
4005 * all groups on cfqd->cfqg_list are being deleted during queue exit.
4006 * Other reference will remain there as we don't want to delete this
4007 * group as it is statically allocated and gets destroyed when
4008 * throtl_data goes away.
4012 if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
4020 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
4023 cfqd->nr_blkcg_linked_grps++;
4025 /* Add group on cfqd->cfqg_list */
4026 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
4029 * Not strictly needed (since RB_ROOT just clears the node and we
4030 * zeroed cfqd on alloc), but better be safe in case someone decides
4031 * to add magic to the rb code
4033 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4034 cfqd->prio_trees[i] = RB_ROOT;
4037 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4038 * Grab a permanent reference to it, so that the normal code flow
4039 * will not attempt to free it.
4041 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4042 cfqd->oom_cfqq.ref++;
4043 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
4045 INIT_LIST_HEAD(&cfqd->cic_list);
4049 init_timer(&cfqd->idle_slice_timer);
4050 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4051 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4053 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4055 cfqd->cfq_quantum = cfq_quantum;
4056 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4057 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4058 cfqd->cfq_back_max = cfq_back_max;
4059 cfqd->cfq_back_penalty = cfq_back_penalty;
4060 cfqd->cfq_slice[0] = cfq_slice_async;
4061 cfqd->cfq_slice[1] = cfq_slice_sync;
4062 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4063 cfqd->cfq_slice_idle = cfq_slice_idle;
4064 cfqd->cfq_group_idle = cfq_group_idle;
4065 cfqd->cfq_latency = 1;
4068 * we optimistically start assuming sync ops weren't delayed in last
4069 * second, in order to have larger depth for async operations.
4071 cfqd->last_delayed_sync = jiffies - HZ;
4075 static void cfq_slab_kill(void)
4078 * Caller already ensured that pending RCU callbacks are completed,
4079 * so we should have no busy allocations at this point.
4082 kmem_cache_destroy(cfq_pool);
4084 kmem_cache_destroy(cfq_ioc_pool);
4087 static int __init cfq_slab_setup(void)
4089 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4093 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
4104 * sysfs parts below -->
4107 cfq_var_show(unsigned int var, char *page)
4109 return sprintf(page, "%d\n", var);
4113 cfq_var_store(unsigned int *var, const char *page, size_t count)
4115 char *p = (char *) page;
4117 *var = simple_strtoul(p, &p, 10);
4121 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4122 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4124 struct cfq_data *cfqd = e->elevator_data; \
4125 unsigned int __data = __VAR; \
4127 __data = jiffies_to_msecs(__data); \
4128 return cfq_var_show(__data, (page)); \
4130 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4131 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4132 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4133 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4134 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4135 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4136 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4137 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4138 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4139 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4140 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4141 #undef SHOW_FUNCTION
4143 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4144 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4146 struct cfq_data *cfqd = e->elevator_data; \
4147 unsigned int __data; \
4148 int ret = cfq_var_store(&__data, (page), count); \
4149 if (__data < (MIN)) \
4151 else if (__data > (MAX)) \
4154 *(__PTR) = msecs_to_jiffies(__data); \
4156 *(__PTR) = __data; \
4159 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4160 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4162 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4164 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4165 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4167 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4168 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4169 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4170 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4171 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4173 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4174 #undef STORE_FUNCTION
4176 #define CFQ_ATTR(name) \
4177 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4179 static struct elv_fs_entry cfq_attrs[] = {
4181 CFQ_ATTR(fifo_expire_sync),
4182 CFQ_ATTR(fifo_expire_async),
4183 CFQ_ATTR(back_seek_max),
4184 CFQ_ATTR(back_seek_penalty),
4185 CFQ_ATTR(slice_sync),
4186 CFQ_ATTR(slice_async),
4187 CFQ_ATTR(slice_async_rq),
4188 CFQ_ATTR(slice_idle),
4189 CFQ_ATTR(group_idle),
4190 CFQ_ATTR(low_latency),
4194 static struct elevator_type iosched_cfq = {
4196 .elevator_merge_fn = cfq_merge,
4197 .elevator_merged_fn = cfq_merged_request,
4198 .elevator_merge_req_fn = cfq_merged_requests,
4199 .elevator_allow_merge_fn = cfq_allow_merge,
4200 .elevator_bio_merged_fn = cfq_bio_merged,
4201 .elevator_dispatch_fn = cfq_dispatch_requests,
4202 .elevator_add_req_fn = cfq_insert_request,
4203 .elevator_activate_req_fn = cfq_activate_request,
4204 .elevator_deactivate_req_fn = cfq_deactivate_request,
4205 .elevator_completed_req_fn = cfq_completed_request,
4206 .elevator_former_req_fn = elv_rb_former_request,
4207 .elevator_latter_req_fn = elv_rb_latter_request,
4208 .elevator_set_req_fn = cfq_set_request,
4209 .elevator_put_req_fn = cfq_put_request,
4210 .elevator_may_queue_fn = cfq_may_queue,
4211 .elevator_init_fn = cfq_init_queue,
4212 .elevator_exit_fn = cfq_exit_queue,
4213 .trim = cfq_free_io_context,
4215 .elevator_attrs = cfq_attrs,
4216 .elevator_name = "cfq",
4217 .elevator_owner = THIS_MODULE,
4220 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4221 static struct blkio_policy_type blkio_policy_cfq = {
4223 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4224 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4226 .plid = BLKIO_POLICY_PROP,
4229 static struct blkio_policy_type blkio_policy_cfq;
4232 static int __init cfq_init(void)
4235 * could be 0 on HZ < 1000 setups
4237 if (!cfq_slice_async)
4238 cfq_slice_async = 1;
4239 if (!cfq_slice_idle)
4242 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4243 if (!cfq_group_idle)
4248 if (cfq_slab_setup())
4251 elv_register(&iosched_cfq);
4252 blkio_policy_register(&blkio_policy_cfq);
4257 static void __exit cfq_exit(void)
4259 DECLARE_COMPLETION_ONSTACK(all_gone);
4260 blkio_policy_unregister(&blkio_policy_cfq);
4261 elv_unregister(&iosched_cfq);
4262 ioc_gone = &all_gone;
4263 /* ioc_gone's update must be visible before reading ioc_count */
4267 * this also protects us from entering cfq_slab_kill() with
4268 * pending RCU callbacks
4270 if (elv_ioc_count_read(cfq_ioc_count))
4271 wait_for_completion(&all_gone);
4275 module_init(cfq_init);
4276 module_exit(cfq_exit);
4278 MODULE_AUTHOR("Jens Axboe");
4279 MODULE_LICENSE("GPL");
4280 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");