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 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
66 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
67 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69 #define sample_valid(samples) ((samples) > 80)
70 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73 * Most of our rbtree usage is for sorting with min extraction, so
74 * if we cache the leftmost node we don't have to walk down the tree
75 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
76 * move this into the elevator for the rq sorting as well.
82 unsigned total_weight;
84 struct cfq_ttime ttime;
86 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
87 .ttime = {.last_end_request = jiffies,},}
90 * Per process-grouping structure
95 /* various state flags, see below */
98 struct cfq_data *cfqd;
99 /* service_tree member */
100 struct rb_node rb_node;
101 /* service_tree key */
102 unsigned long rb_key;
103 /* prio tree member */
104 struct rb_node p_node;
105 /* prio tree root we belong to, if any */
106 struct rb_root *p_root;
107 /* sorted list of pending requests */
108 struct rb_root sort_list;
109 /* if fifo isn't expired, next request to serve */
110 struct request *next_rq;
111 /* requests queued in sort_list */
113 /* currently allocated requests */
115 /* fifo list of requests in sort_list */
116 struct list_head fifo;
118 /* time when queue got scheduled in to dispatch first request. */
119 unsigned long dispatch_start;
120 unsigned int allocated_slice;
121 unsigned int slice_dispatch;
122 /* time when first request from queue completed and slice started. */
123 unsigned long slice_start;
124 unsigned long slice_end;
127 /* pending priority requests */
129 /* number of requests that are on the dispatch list or inside driver */
132 /* io prio of this group */
133 unsigned short ioprio, org_ioprio;
134 unsigned short ioprio_class;
139 sector_t last_request_pos;
141 struct cfq_rb_root *service_tree;
142 struct cfq_queue *new_cfqq;
143 struct cfq_group *cfqg;
144 /* Number of sectors dispatched from queue in single dispatch round */
145 unsigned long nr_sectors;
149 * First index in the service_trees.
150 * IDLE is handled separately, so it has negative index
160 * Second index in the service_trees.
164 SYNC_NOIDLE_WORKLOAD = 1,
168 /* This is per cgroup per device grouping structure */
170 /* group service_tree member */
171 struct rb_node rb_node;
173 /* group service_tree key */
176 unsigned int new_weight;
179 /* number of cfqq currently on this group */
183 * Per group busy queues average. Useful for workload slice calc. We
184 * create the array for each prio class but at run time it is used
185 * only for RT and BE class and slot for IDLE class remains unused.
186 * This is primarily done to avoid confusion and a gcc warning.
188 unsigned int busy_queues_avg[CFQ_PRIO_NR];
190 * rr lists of queues with requests. We maintain service trees for
191 * RT and BE classes. These trees are subdivided in subclasses
192 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
193 * class there is no subclassification and all the cfq queues go on
194 * a single tree service_tree_idle.
195 * Counts are embedded in the cfq_rb_root
197 struct cfq_rb_root service_trees[2][3];
198 struct cfq_rb_root service_tree_idle;
200 unsigned long saved_workload_slice;
201 enum wl_type_t saved_workload;
202 enum wl_prio_t saved_serving_prio;
203 struct blkio_group blkg;
204 #ifdef CONFIG_CFQ_GROUP_IOSCHED
205 struct hlist_node cfqd_node;
208 /* number of requests that are on the dispatch list or inside driver */
210 struct cfq_ttime ttime;
214 * Per block device queue structure
217 struct request_queue *queue;
218 /* Root service tree for cfq_groups */
219 struct cfq_rb_root grp_service_tree;
220 struct cfq_group root_group;
223 * The priority currently being served
225 enum wl_prio_t serving_prio;
226 enum wl_type_t serving_type;
227 unsigned long workload_expires;
228 struct cfq_group *serving_group;
231 * Each priority tree is sorted by next_request position. These
232 * trees are used when determining if two or more queues are
233 * interleaving requests (see cfq_close_cooperator).
235 struct rb_root prio_trees[CFQ_PRIO_LISTS];
237 unsigned int busy_queues;
238 unsigned int busy_sync_queues;
244 * queue-depth detection
250 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
251 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
254 int hw_tag_est_depth;
255 unsigned int hw_tag_samples;
258 * idle window management
260 struct timer_list idle_slice_timer;
261 struct work_struct unplug_work;
263 struct cfq_queue *active_queue;
264 struct cfq_io_context *active_cic;
267 * async queue for each priority case
269 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
270 struct cfq_queue *async_idle_cfqq;
272 sector_t last_position;
275 * tunables, see top of file
277 unsigned int cfq_quantum;
278 unsigned int cfq_fifo_expire[2];
279 unsigned int cfq_back_penalty;
280 unsigned int cfq_back_max;
281 unsigned int cfq_slice[2];
282 unsigned int cfq_slice_async_rq;
283 unsigned int cfq_slice_idle;
284 unsigned int cfq_group_idle;
285 unsigned int cfq_latency;
287 struct list_head cic_list;
290 * Fallback dummy cfqq for extreme OOM conditions
292 struct cfq_queue oom_cfqq;
294 unsigned long last_delayed_sync;
296 /* List of cfq groups being managed on this device*/
297 struct hlist_head cfqg_list;
299 /* Number of groups which are on blkcg->blkg_list */
300 unsigned int nr_blkcg_linked_grps;
303 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
305 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
312 if (prio == IDLE_WORKLOAD)
313 return &cfqg->service_tree_idle;
315 return &cfqg->service_trees[prio][type];
318 enum cfqq_state_flags {
319 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
320 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
321 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
322 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
323 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
324 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
325 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
326 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
327 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
328 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
329 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
330 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
331 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
334 #define CFQ_CFQQ_FNS(name) \
335 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
337 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
339 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
343 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
345 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
349 CFQ_CFQQ_FNS(wait_request);
350 CFQ_CFQQ_FNS(must_dispatch);
351 CFQ_CFQQ_FNS(must_alloc_slice);
352 CFQ_CFQQ_FNS(fifo_expire);
353 CFQ_CFQQ_FNS(idle_window);
354 CFQ_CFQQ_FNS(prio_changed);
355 CFQ_CFQQ_FNS(slice_new);
358 CFQ_CFQQ_FNS(split_coop);
360 CFQ_CFQQ_FNS(wait_busy);
363 #ifdef CONFIG_CFQ_GROUP_IOSCHED
364 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
365 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
366 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
367 blkg_path(&(cfqq)->cfqg->blkg), ##args)
369 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
370 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
371 blkg_path(&(cfqg)->blkg), ##args) \
374 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
376 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
378 #define cfq_log(cfqd, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
381 /* Traverses through cfq group service trees */
382 #define for_each_cfqg_st(cfqg, i, j, st) \
383 for (i = 0; i <= IDLE_WORKLOAD; i++) \
384 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
385 : &cfqg->service_tree_idle; \
386 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
387 (i == IDLE_WORKLOAD && j == 0); \
388 j++, st = i < IDLE_WORKLOAD ? \
389 &cfqg->service_trees[i][j]: NULL) \
391 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
392 struct cfq_ttime *ttime, bool group_idle)
395 if (!sample_valid(ttime->ttime_samples))
398 slice = cfqd->cfq_group_idle;
400 slice = cfqd->cfq_slice_idle;
401 return ttime->ttime_mean > slice;
404 static inline bool iops_mode(struct cfq_data *cfqd)
407 * If we are not idling on queues and it is a NCQ drive, parallel
408 * execution of requests is on and measuring time is not possible
409 * in most of the cases until and unless we drive shallower queue
410 * depths and that becomes a performance bottleneck. In such cases
411 * switch to start providing fairness in terms of number of IOs.
413 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
419 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
421 if (cfq_class_idle(cfqq))
422 return IDLE_WORKLOAD;
423 if (cfq_class_rt(cfqq))
429 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
431 if (!cfq_cfqq_sync(cfqq))
432 return ASYNC_WORKLOAD;
433 if (!cfq_cfqq_idle_window(cfqq))
434 return SYNC_NOIDLE_WORKLOAD;
435 return SYNC_WORKLOAD;
438 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
439 struct cfq_data *cfqd,
440 struct cfq_group *cfqg)
442 if (wl == IDLE_WORKLOAD)
443 return cfqg->service_tree_idle.count;
445 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
446 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
447 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
450 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
451 struct cfq_group *cfqg)
453 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
454 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
457 static void cfq_dispatch_insert(struct request_queue *, struct request *);
458 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
459 struct io_context *, gfp_t);
460 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
461 struct io_context *);
463 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
466 return cic->cfqq[is_sync];
469 static inline void cic_set_cfqq(struct cfq_io_context *cic,
470 struct cfq_queue *cfqq, bool is_sync)
472 cic->cfqq[is_sync] = cfqq;
475 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
477 return cic->q->elevator->elevator_data;
481 * We regard a request as SYNC, if it's either a read or has the SYNC bit
482 * set (in which case it could also be direct WRITE).
484 static inline bool cfq_bio_sync(struct bio *bio)
486 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
490 * scheduler run of queue, if there are requests pending and no one in the
491 * driver that will restart queueing
493 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
495 if (cfqd->busy_queues) {
496 cfq_log(cfqd, "schedule dispatch");
497 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
502 * Scale schedule slice based on io priority. Use the sync time slice only
503 * if a queue is marked sync and has sync io queued. A sync queue with async
504 * io only, should not get full sync slice length.
506 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
509 const int base_slice = cfqd->cfq_slice[sync];
511 WARN_ON(prio >= IOPRIO_BE_NR);
513 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
517 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
519 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
522 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
524 u64 d = delta << CFQ_SERVICE_SHIFT;
526 d = d * BLKIO_WEIGHT_DEFAULT;
527 do_div(d, cfqg->weight);
531 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
533 s64 delta = (s64)(vdisktime - min_vdisktime);
535 min_vdisktime = vdisktime;
537 return min_vdisktime;
540 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
542 s64 delta = (s64)(vdisktime - min_vdisktime);
544 min_vdisktime = vdisktime;
546 return min_vdisktime;
549 static void update_min_vdisktime(struct cfq_rb_root *st)
551 struct cfq_group *cfqg;
554 cfqg = rb_entry_cfqg(st->left);
555 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
561 * get averaged number of queues of RT/BE priority.
562 * average is updated, with a formula that gives more weight to higher numbers,
563 * to quickly follows sudden increases and decrease slowly
566 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
567 struct cfq_group *cfqg, bool rt)
569 unsigned min_q, max_q;
570 unsigned mult = cfq_hist_divisor - 1;
571 unsigned round = cfq_hist_divisor / 2;
572 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
574 min_q = min(cfqg->busy_queues_avg[rt], busy);
575 max_q = max(cfqg->busy_queues_avg[rt], busy);
576 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
578 return cfqg->busy_queues_avg[rt];
581 static inline unsigned
582 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
584 struct cfq_rb_root *st = &cfqd->grp_service_tree;
586 return cfq_target_latency * cfqg->weight / st->total_weight;
589 static inline unsigned
590 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
592 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
593 if (cfqd->cfq_latency) {
595 * interested queues (we consider only the ones with the same
596 * priority class in the cfq group)
598 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
600 unsigned sync_slice = cfqd->cfq_slice[1];
601 unsigned expect_latency = sync_slice * iq;
602 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
604 if (expect_latency > group_slice) {
605 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
606 /* scale low_slice according to IO priority
607 * and sync vs async */
609 min(slice, base_low_slice * slice / sync_slice);
610 /* the adapted slice value is scaled to fit all iqs
611 * into the target latency */
612 slice = max(slice * group_slice / expect_latency,
620 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
622 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
624 cfqq->slice_start = jiffies;
625 cfqq->slice_end = jiffies + slice;
626 cfqq->allocated_slice = slice;
627 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
631 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
632 * isn't valid until the first request from the dispatch is activated
633 * and the slice time set.
635 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
637 if (cfq_cfqq_slice_new(cfqq))
639 if (time_before(jiffies, cfqq->slice_end))
646 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
647 * We choose the request that is closest to the head right now. Distance
648 * behind the head is penalized and only allowed to a certain extent.
650 static struct request *
651 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
653 sector_t s1, s2, d1 = 0, d2 = 0;
654 unsigned long back_max;
655 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
656 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
657 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
659 if (rq1 == NULL || rq1 == rq2)
664 if (rq_is_sync(rq1) != rq_is_sync(rq2))
665 return rq_is_sync(rq1) ? rq1 : rq2;
667 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
668 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
670 s1 = blk_rq_pos(rq1);
671 s2 = blk_rq_pos(rq2);
674 * by definition, 1KiB is 2 sectors
676 back_max = cfqd->cfq_back_max * 2;
679 * Strict one way elevator _except_ in the case where we allow
680 * short backward seeks which are biased as twice the cost of a
681 * similar forward seek.
685 else if (s1 + back_max >= last)
686 d1 = (last - s1) * cfqd->cfq_back_penalty;
688 wrap |= CFQ_RQ1_WRAP;
692 else if (s2 + back_max >= last)
693 d2 = (last - s2) * cfqd->cfq_back_penalty;
695 wrap |= CFQ_RQ2_WRAP;
697 /* Found required data */
700 * By doing switch() on the bit mask "wrap" we avoid having to
701 * check two variables for all permutations: --> faster!
704 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
720 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
723 * Since both rqs are wrapped,
724 * start with the one that's further behind head
725 * (--> only *one* back seek required),
726 * since back seek takes more time than forward.
736 * The below is leftmost cache rbtree addon
738 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
740 /* Service tree is empty */
745 root->left = rb_first(&root->rb);
748 return rb_entry(root->left, struct cfq_queue, rb_node);
753 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
756 root->left = rb_first(&root->rb);
759 return rb_entry_cfqg(root->left);
764 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
770 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
774 rb_erase_init(n, &root->rb);
779 * would be nice to take fifo expire time into account as well
781 static struct request *
782 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
783 struct request *last)
785 struct rb_node *rbnext = rb_next(&last->rb_node);
786 struct rb_node *rbprev = rb_prev(&last->rb_node);
787 struct request *next = NULL, *prev = NULL;
789 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
792 prev = rb_entry_rq(rbprev);
795 next = rb_entry_rq(rbnext);
797 rbnext = rb_first(&cfqq->sort_list);
798 if (rbnext && rbnext != &last->rb_node)
799 next = rb_entry_rq(rbnext);
802 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
805 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
806 struct cfq_queue *cfqq)
809 * just an approximation, should be ok.
811 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
812 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
816 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
818 return cfqg->vdisktime - st->min_vdisktime;
822 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
824 struct rb_node **node = &st->rb.rb_node;
825 struct rb_node *parent = NULL;
826 struct cfq_group *__cfqg;
827 s64 key = cfqg_key(st, cfqg);
830 while (*node != NULL) {
832 __cfqg = rb_entry_cfqg(parent);
834 if (key < cfqg_key(st, __cfqg))
835 node = &parent->rb_left;
837 node = &parent->rb_right;
843 st->left = &cfqg->rb_node;
845 rb_link_node(&cfqg->rb_node, parent, node);
846 rb_insert_color(&cfqg->rb_node, &st->rb);
850 cfq_update_group_weight(struct cfq_group *cfqg)
852 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
853 if (cfqg->needs_update) {
854 cfqg->weight = cfqg->new_weight;
855 cfqg->needs_update = false;
860 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
862 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
864 cfq_update_group_weight(cfqg);
865 __cfq_group_service_tree_add(st, cfqg);
866 st->total_weight += cfqg->weight;
870 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
872 struct cfq_rb_root *st = &cfqd->grp_service_tree;
873 struct cfq_group *__cfqg;
877 if (!RB_EMPTY_NODE(&cfqg->rb_node))
881 * Currently put the group at the end. Later implement something
882 * so that groups get lesser vtime based on their weights, so that
883 * if group does not loose all if it was not continuously backlogged.
885 n = rb_last(&st->rb);
887 __cfqg = rb_entry_cfqg(n);
888 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
890 cfqg->vdisktime = st->min_vdisktime;
891 cfq_group_service_tree_add(st, cfqg);
895 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
897 st->total_weight -= cfqg->weight;
898 if (!RB_EMPTY_NODE(&cfqg->rb_node))
899 cfq_rb_erase(&cfqg->rb_node, st);
903 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
905 struct cfq_rb_root *st = &cfqd->grp_service_tree;
907 BUG_ON(cfqg->nr_cfqq < 1);
910 /* If there are other cfq queues under this group, don't delete it */
914 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
915 cfq_group_service_tree_del(st, cfqg);
916 cfqg->saved_workload_slice = 0;
917 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
920 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
921 unsigned int *unaccounted_time)
923 unsigned int slice_used;
926 * Queue got expired before even a single request completed or
927 * got expired immediately after first request completion.
929 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
931 * Also charge the seek time incurred to the group, otherwise
932 * if there are mutiple queues in the group, each can dispatch
933 * a single request on seeky media and cause lots of seek time
934 * and group will never know it.
936 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
939 slice_used = jiffies - cfqq->slice_start;
940 if (slice_used > cfqq->allocated_slice) {
941 *unaccounted_time = slice_used - cfqq->allocated_slice;
942 slice_used = cfqq->allocated_slice;
944 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
945 *unaccounted_time += cfqq->slice_start -
946 cfqq->dispatch_start;
952 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
953 struct cfq_queue *cfqq)
955 struct cfq_rb_root *st = &cfqd->grp_service_tree;
956 unsigned int used_sl, charge, unaccounted_sl = 0;
957 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
958 - cfqg->service_tree_idle.count;
961 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
964 charge = cfqq->slice_dispatch;
965 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
966 charge = cfqq->allocated_slice;
968 /* Can't update vdisktime while group is on service tree */
969 cfq_group_service_tree_del(st, cfqg);
970 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
971 /* If a new weight was requested, update now, off tree */
972 cfq_group_service_tree_add(st, cfqg);
974 /* This group is being expired. Save the context */
975 if (time_after(cfqd->workload_expires, jiffies)) {
976 cfqg->saved_workload_slice = cfqd->workload_expires
978 cfqg->saved_workload = cfqd->serving_type;
979 cfqg->saved_serving_prio = cfqd->serving_prio;
981 cfqg->saved_workload_slice = 0;
983 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
985 cfq_log_cfqq(cfqq->cfqd, cfqq,
986 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
987 used_sl, cfqq->slice_dispatch, charge,
988 iops_mode(cfqd), cfqq->nr_sectors);
989 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
991 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
994 #ifdef CONFIG_CFQ_GROUP_IOSCHED
995 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
998 return container_of(blkg, struct cfq_group, blkg);
1002 static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1003 unsigned int weight)
1005 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1006 cfqg->new_weight = weight;
1007 cfqg->needs_update = true;
1010 static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
1011 struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
1013 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1014 unsigned int major, minor;
1017 * Add group onto cgroup list. It might happen that bdi->dev is
1018 * not initialized yet. Initialize this new group without major
1019 * and minor info and this info will be filled in once a new thread
1023 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1024 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1025 (void *)cfqd, MKDEV(major, minor));
1027 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1030 cfqd->nr_blkcg_linked_grps++;
1031 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1033 /* Add group on cfqd list */
1034 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1038 * Should be called from sleepable context. No request queue lock as per
1039 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1040 * from sleepable context.
1042 static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
1044 struct cfq_group *cfqg = NULL;
1046 struct cfq_rb_root *st;
1048 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1052 for_each_cfqg_st(cfqg, i, j, st)
1054 RB_CLEAR_NODE(&cfqg->rb_node);
1056 cfqg->ttime.last_end_request = jiffies;
1059 * Take the initial reference that will be released on destroy
1060 * This can be thought of a joint reference by cgroup and
1061 * elevator which will be dropped by either elevator exit
1062 * or cgroup deletion path depending on who is exiting first.
1066 ret = blkio_alloc_blkg_stats(&cfqg->blkg);
1075 static struct cfq_group *
1076 cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
1078 struct cfq_group *cfqg = NULL;
1080 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1081 unsigned int major, minor;
1084 * This is the common case when there are no blkio cgroups.
1085 * Avoid lookup in this case
1087 if (blkcg == &blkio_root_cgroup)
1088 cfqg = &cfqd->root_group;
1090 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1092 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1093 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1094 cfqg->blkg.dev = MKDEV(major, minor);
1101 * Search for the cfq group current task belongs to. request_queue lock must
1104 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1106 struct blkio_cgroup *blkcg;
1107 struct cfq_group *cfqg = NULL, *__cfqg = NULL;
1108 struct request_queue *q = cfqd->queue;
1111 blkcg = task_blkio_cgroup(current);
1112 cfqg = cfq_find_cfqg(cfqd, blkcg);
1119 * Need to allocate a group. Allocation of group also needs allocation
1120 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1121 * we need to drop rcu lock and queue_lock before we call alloc.
1123 * Not taking any queue reference here and assuming that queue is
1124 * around by the time we return. CFQ queue allocation code does
1125 * the same. It might be racy though.
1129 spin_unlock_irq(q->queue_lock);
1131 cfqg = cfq_alloc_cfqg(cfqd);
1133 spin_lock_irq(q->queue_lock);
1136 blkcg = task_blkio_cgroup(current);
1139 * If some other thread already allocated the group while we were
1140 * not holding queue lock, free up the group
1142 __cfqg = cfq_find_cfqg(cfqd, blkcg);
1151 cfqg = &cfqd->root_group;
1153 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
1158 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1164 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1166 /* Currently, all async queues are mapped to root group */
1167 if (!cfq_cfqq_sync(cfqq))
1168 cfqg = &cfqq->cfqd->root_group;
1171 /* cfqq reference on cfqg */
1175 static void cfq_put_cfqg(struct cfq_group *cfqg)
1177 struct cfq_rb_root *st;
1180 BUG_ON(cfqg->ref <= 0);
1184 for_each_cfqg_st(cfqg, i, j, st)
1185 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1186 free_percpu(cfqg->blkg.stats_cpu);
1190 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1192 /* Something wrong if we are trying to remove same group twice */
1193 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1195 hlist_del_init(&cfqg->cfqd_node);
1197 BUG_ON(cfqd->nr_blkcg_linked_grps <= 0);
1198 cfqd->nr_blkcg_linked_grps--;
1201 * Put the reference taken at the time of creation so that when all
1202 * queues are gone, group can be destroyed.
1207 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1209 struct hlist_node *pos, *n;
1210 struct cfq_group *cfqg;
1212 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1214 * If cgroup removal path got to blk_group first and removed
1215 * it from cgroup list, then it will take care of destroying
1218 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1219 cfq_destroy_cfqg(cfqd, cfqg);
1224 * Blk cgroup controller notification saying that blkio_group object is being
1225 * delinked as associated cgroup object is going away. That also means that
1226 * no new IO will come in this group. So get rid of this group as soon as
1227 * any pending IO in the group is finished.
1229 * This function is called under rcu_read_lock(). key is the rcu protected
1230 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1233 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1234 * it should not be NULL as even if elevator was exiting, cgroup deltion
1235 * path got to it first.
1237 static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1239 unsigned long flags;
1240 struct cfq_data *cfqd = key;
1242 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1243 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1244 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1247 #else /* GROUP_IOSCHED */
1248 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1250 return &cfqd->root_group;
1253 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1259 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1263 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1264 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1266 #endif /* GROUP_IOSCHED */
1269 * The cfqd->service_trees holds all pending cfq_queue's that have
1270 * requests waiting to be processed. It is sorted in the order that
1271 * we will service the queues.
1273 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1276 struct rb_node **p, *parent;
1277 struct cfq_queue *__cfqq;
1278 unsigned long rb_key;
1279 struct cfq_rb_root *service_tree;
1283 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1285 if (cfq_class_idle(cfqq)) {
1286 rb_key = CFQ_IDLE_DELAY;
1287 parent = rb_last(&service_tree->rb);
1288 if (parent && parent != &cfqq->rb_node) {
1289 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1290 rb_key += __cfqq->rb_key;
1293 } else if (!add_front) {
1295 * Get our rb key offset. Subtract any residual slice
1296 * value carried from last service. A negative resid
1297 * count indicates slice overrun, and this should position
1298 * the next service time further away in the tree.
1300 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1301 rb_key -= cfqq->slice_resid;
1302 cfqq->slice_resid = 0;
1305 __cfqq = cfq_rb_first(service_tree);
1306 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1309 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1312 * same position, nothing more to do
1314 if (rb_key == cfqq->rb_key &&
1315 cfqq->service_tree == service_tree)
1318 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1319 cfqq->service_tree = NULL;
1324 cfqq->service_tree = service_tree;
1325 p = &service_tree->rb.rb_node;
1330 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1333 * sort by key, that represents service time.
1335 if (time_before(rb_key, __cfqq->rb_key))
1338 n = &(*p)->rb_right;
1346 service_tree->left = &cfqq->rb_node;
1348 cfqq->rb_key = rb_key;
1349 rb_link_node(&cfqq->rb_node, parent, p);
1350 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1351 service_tree->count++;
1352 if (add_front || !new_cfqq)
1354 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1357 static struct cfq_queue *
1358 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1359 sector_t sector, struct rb_node **ret_parent,
1360 struct rb_node ***rb_link)
1362 struct rb_node **p, *parent;
1363 struct cfq_queue *cfqq = NULL;
1371 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1374 * Sort strictly based on sector. Smallest to the left,
1375 * largest to the right.
1377 if (sector > blk_rq_pos(cfqq->next_rq))
1378 n = &(*p)->rb_right;
1379 else if (sector < blk_rq_pos(cfqq->next_rq))
1387 *ret_parent = parent;
1393 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1395 struct rb_node **p, *parent;
1396 struct cfq_queue *__cfqq;
1399 rb_erase(&cfqq->p_node, cfqq->p_root);
1400 cfqq->p_root = NULL;
1403 if (cfq_class_idle(cfqq))
1408 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1409 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1410 blk_rq_pos(cfqq->next_rq), &parent, &p);
1412 rb_link_node(&cfqq->p_node, parent, p);
1413 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1415 cfqq->p_root = NULL;
1419 * Update cfqq's position in the service tree.
1421 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1424 * Resorting requires the cfqq to be on the RR list already.
1426 if (cfq_cfqq_on_rr(cfqq)) {
1427 cfq_service_tree_add(cfqd, cfqq, 0);
1428 cfq_prio_tree_add(cfqd, cfqq);
1433 * add to busy list of queues for service, trying to be fair in ordering
1434 * the pending list according to last request service
1436 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1438 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1439 BUG_ON(cfq_cfqq_on_rr(cfqq));
1440 cfq_mark_cfqq_on_rr(cfqq);
1441 cfqd->busy_queues++;
1442 if (cfq_cfqq_sync(cfqq))
1443 cfqd->busy_sync_queues++;
1445 cfq_resort_rr_list(cfqd, cfqq);
1449 * Called when the cfqq no longer has requests pending, remove it from
1452 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1454 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1455 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1456 cfq_clear_cfqq_on_rr(cfqq);
1458 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1459 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1460 cfqq->service_tree = NULL;
1463 rb_erase(&cfqq->p_node, cfqq->p_root);
1464 cfqq->p_root = NULL;
1467 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1468 BUG_ON(!cfqd->busy_queues);
1469 cfqd->busy_queues--;
1470 if (cfq_cfqq_sync(cfqq))
1471 cfqd->busy_sync_queues--;
1475 * rb tree support functions
1477 static void cfq_del_rq_rb(struct request *rq)
1479 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1480 const int sync = rq_is_sync(rq);
1482 BUG_ON(!cfqq->queued[sync]);
1483 cfqq->queued[sync]--;
1485 elv_rb_del(&cfqq->sort_list, rq);
1487 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1489 * Queue will be deleted from service tree when we actually
1490 * expire it later. Right now just remove it from prio tree
1494 rb_erase(&cfqq->p_node, cfqq->p_root);
1495 cfqq->p_root = NULL;
1500 static void cfq_add_rq_rb(struct request *rq)
1502 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1503 struct cfq_data *cfqd = cfqq->cfqd;
1504 struct request *prev;
1506 cfqq->queued[rq_is_sync(rq)]++;
1508 elv_rb_add(&cfqq->sort_list, rq);
1510 if (!cfq_cfqq_on_rr(cfqq))
1511 cfq_add_cfqq_rr(cfqd, cfqq);
1514 * check if this request is a better next-serve candidate
1516 prev = cfqq->next_rq;
1517 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1520 * adjust priority tree position, if ->next_rq changes
1522 if (prev != cfqq->next_rq)
1523 cfq_prio_tree_add(cfqd, cfqq);
1525 BUG_ON(!cfqq->next_rq);
1528 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1530 elv_rb_del(&cfqq->sort_list, rq);
1531 cfqq->queued[rq_is_sync(rq)]--;
1532 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1533 rq_data_dir(rq), rq_is_sync(rq));
1535 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1536 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1540 static struct request *
1541 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1543 struct task_struct *tsk = current;
1544 struct cfq_io_context *cic;
1545 struct cfq_queue *cfqq;
1547 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1551 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1553 sector_t sector = bio->bi_sector + bio_sectors(bio);
1555 return elv_rb_find(&cfqq->sort_list, sector);
1561 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1563 struct cfq_data *cfqd = q->elevator->elevator_data;
1565 cfqd->rq_in_driver++;
1566 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1567 cfqd->rq_in_driver);
1569 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1572 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1574 struct cfq_data *cfqd = q->elevator->elevator_data;
1576 WARN_ON(!cfqd->rq_in_driver);
1577 cfqd->rq_in_driver--;
1578 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1579 cfqd->rq_in_driver);
1582 static void cfq_remove_request(struct request *rq)
1584 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1586 if (cfqq->next_rq == rq)
1587 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1589 list_del_init(&rq->queuelist);
1592 cfqq->cfqd->rq_queued--;
1593 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1594 rq_data_dir(rq), rq_is_sync(rq));
1595 if (rq->cmd_flags & REQ_PRIO) {
1596 WARN_ON(!cfqq->prio_pending);
1597 cfqq->prio_pending--;
1601 static int cfq_merge(struct request_queue *q, struct request **req,
1604 struct cfq_data *cfqd = q->elevator->elevator_data;
1605 struct request *__rq;
1607 __rq = cfq_find_rq_fmerge(cfqd, bio);
1608 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1610 return ELEVATOR_FRONT_MERGE;
1613 return ELEVATOR_NO_MERGE;
1616 static void cfq_merged_request(struct request_queue *q, struct request *req,
1619 if (type == ELEVATOR_FRONT_MERGE) {
1620 struct cfq_queue *cfqq = RQ_CFQQ(req);
1622 cfq_reposition_rq_rb(cfqq, req);
1626 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1629 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1630 bio_data_dir(bio), cfq_bio_sync(bio));
1634 cfq_merged_requests(struct request_queue *q, struct request *rq,
1635 struct request *next)
1637 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1639 * reposition in fifo if next is older than rq
1641 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1642 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1643 list_move(&rq->queuelist, &next->queuelist);
1644 rq_set_fifo_time(rq, rq_fifo_time(next));
1647 if (cfqq->next_rq == next)
1649 cfq_remove_request(next);
1650 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1651 rq_data_dir(next), rq_is_sync(next));
1654 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1657 struct cfq_data *cfqd = q->elevator->elevator_data;
1658 struct cfq_io_context *cic;
1659 struct cfq_queue *cfqq;
1662 * Disallow merge of a sync bio into an async request.
1664 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1668 * Lookup the cfqq that this bio will be queued with and allow
1669 * merge only if rq is queued there. This function can be called
1670 * from plug merge without queue_lock. In such cases, ioc of @rq
1671 * and %current are guaranteed to be equal. Avoid lookup which
1672 * requires queue_lock by using @rq's cic.
1674 if (current->io_context == RQ_CIC(rq)->ioc) {
1677 cic = cfq_cic_lookup(cfqd, current->io_context);
1682 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1683 return cfqq == RQ_CFQQ(rq);
1686 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1688 del_timer(&cfqd->idle_slice_timer);
1689 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1692 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1693 struct cfq_queue *cfqq)
1696 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1697 cfqd->serving_prio, cfqd->serving_type);
1698 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1699 cfqq->slice_start = 0;
1700 cfqq->dispatch_start = jiffies;
1701 cfqq->allocated_slice = 0;
1702 cfqq->slice_end = 0;
1703 cfqq->slice_dispatch = 0;
1704 cfqq->nr_sectors = 0;
1706 cfq_clear_cfqq_wait_request(cfqq);
1707 cfq_clear_cfqq_must_dispatch(cfqq);
1708 cfq_clear_cfqq_must_alloc_slice(cfqq);
1709 cfq_clear_cfqq_fifo_expire(cfqq);
1710 cfq_mark_cfqq_slice_new(cfqq);
1712 cfq_del_timer(cfqd, cfqq);
1715 cfqd->active_queue = cfqq;
1719 * current cfqq expired its slice (or was too idle), select new one
1722 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1725 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1727 if (cfq_cfqq_wait_request(cfqq))
1728 cfq_del_timer(cfqd, cfqq);
1730 cfq_clear_cfqq_wait_request(cfqq);
1731 cfq_clear_cfqq_wait_busy(cfqq);
1734 * If this cfqq is shared between multiple processes, check to
1735 * make sure that those processes are still issuing I/Os within
1736 * the mean seek distance. If not, it may be time to break the
1737 * queues apart again.
1739 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1740 cfq_mark_cfqq_split_coop(cfqq);
1743 * store what was left of this slice, if the queue idled/timed out
1746 if (cfq_cfqq_slice_new(cfqq))
1747 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1749 cfqq->slice_resid = cfqq->slice_end - jiffies;
1750 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1753 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1755 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1756 cfq_del_cfqq_rr(cfqd, cfqq);
1758 cfq_resort_rr_list(cfqd, cfqq);
1760 if (cfqq == cfqd->active_queue)
1761 cfqd->active_queue = NULL;
1763 if (cfqd->active_cic) {
1764 put_io_context(cfqd->active_cic->ioc, cfqd->queue);
1765 cfqd->active_cic = NULL;
1769 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1771 struct cfq_queue *cfqq = cfqd->active_queue;
1774 __cfq_slice_expired(cfqd, cfqq, timed_out);
1778 * Get next queue for service. Unless we have a queue preemption,
1779 * we'll simply select the first cfqq in the service tree.
1781 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1783 struct cfq_rb_root *service_tree =
1784 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1785 cfqd->serving_type);
1787 if (!cfqd->rq_queued)
1790 /* There is nothing to dispatch */
1793 if (RB_EMPTY_ROOT(&service_tree->rb))
1795 return cfq_rb_first(service_tree);
1798 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1800 struct cfq_group *cfqg;
1801 struct cfq_queue *cfqq;
1803 struct cfq_rb_root *st;
1805 if (!cfqd->rq_queued)
1808 cfqg = cfq_get_next_cfqg(cfqd);
1812 for_each_cfqg_st(cfqg, i, j, st)
1813 if ((cfqq = cfq_rb_first(st)) != NULL)
1819 * Get and set a new active queue for service.
1821 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1822 struct cfq_queue *cfqq)
1825 cfqq = cfq_get_next_queue(cfqd);
1827 __cfq_set_active_queue(cfqd, cfqq);
1831 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1834 if (blk_rq_pos(rq) >= cfqd->last_position)
1835 return blk_rq_pos(rq) - cfqd->last_position;
1837 return cfqd->last_position - blk_rq_pos(rq);
1840 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1843 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1846 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1847 struct cfq_queue *cur_cfqq)
1849 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1850 struct rb_node *parent, *node;
1851 struct cfq_queue *__cfqq;
1852 sector_t sector = cfqd->last_position;
1854 if (RB_EMPTY_ROOT(root))
1858 * First, if we find a request starting at the end of the last
1859 * request, choose it.
1861 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1866 * If the exact sector wasn't found, the parent of the NULL leaf
1867 * will contain the closest sector.
1869 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1870 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1873 if (blk_rq_pos(__cfqq->next_rq) < sector)
1874 node = rb_next(&__cfqq->p_node);
1876 node = rb_prev(&__cfqq->p_node);
1880 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1881 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1889 * cur_cfqq - passed in so that we don't decide that the current queue is
1890 * closely cooperating with itself.
1892 * So, basically we're assuming that that cur_cfqq has dispatched at least
1893 * one request, and that cfqd->last_position reflects a position on the disk
1894 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1897 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1898 struct cfq_queue *cur_cfqq)
1900 struct cfq_queue *cfqq;
1902 if (cfq_class_idle(cur_cfqq))
1904 if (!cfq_cfqq_sync(cur_cfqq))
1906 if (CFQQ_SEEKY(cur_cfqq))
1910 * Don't search priority tree if it's the only queue in the group.
1912 if (cur_cfqq->cfqg->nr_cfqq == 1)
1916 * We should notice if some of the queues are cooperating, eg
1917 * working closely on the same area of the disk. In that case,
1918 * we can group them together and don't waste time idling.
1920 cfqq = cfqq_close(cfqd, cur_cfqq);
1924 /* If new queue belongs to different cfq_group, don't choose it */
1925 if (cur_cfqq->cfqg != cfqq->cfqg)
1929 * It only makes sense to merge sync queues.
1931 if (!cfq_cfqq_sync(cfqq))
1933 if (CFQQ_SEEKY(cfqq))
1937 * Do not merge queues of different priority classes
1939 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1946 * Determine whether we should enforce idle window for this queue.
1949 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1951 enum wl_prio_t prio = cfqq_prio(cfqq);
1952 struct cfq_rb_root *service_tree = cfqq->service_tree;
1954 BUG_ON(!service_tree);
1955 BUG_ON(!service_tree->count);
1957 if (!cfqd->cfq_slice_idle)
1960 /* We never do for idle class queues. */
1961 if (prio == IDLE_WORKLOAD)
1964 /* We do for queues that were marked with idle window flag. */
1965 if (cfq_cfqq_idle_window(cfqq) &&
1966 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1970 * Otherwise, we do only if they are the last ones
1971 * in their service tree.
1973 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
1974 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
1976 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1977 service_tree->count);
1981 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1983 struct cfq_queue *cfqq = cfqd->active_queue;
1984 struct cfq_io_context *cic;
1985 unsigned long sl, group_idle = 0;
1988 * SSD device without seek penalty, disable idling. But only do so
1989 * for devices that support queuing, otherwise we still have a problem
1990 * with sync vs async workloads.
1992 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1995 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1996 WARN_ON(cfq_cfqq_slice_new(cfqq));
1999 * idle is disabled, either manually or by past process history
2001 if (!cfq_should_idle(cfqd, cfqq)) {
2002 /* no queue idling. Check for group idling */
2003 if (cfqd->cfq_group_idle)
2004 group_idle = cfqd->cfq_group_idle;
2010 * still active requests from this queue, don't idle
2012 if (cfqq->dispatched)
2016 * task has exited, don't wait
2018 cic = cfqd->active_cic;
2019 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
2023 * If our average think time is larger than the remaining time
2024 * slice, then don't idle. This avoids overrunning the allotted
2027 if (sample_valid(cic->ttime.ttime_samples) &&
2028 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2029 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2030 cic->ttime.ttime_mean);
2034 /* There are other queues in the group, don't do group idle */
2035 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2038 cfq_mark_cfqq_wait_request(cfqq);
2041 sl = cfqd->cfq_group_idle;
2043 sl = cfqd->cfq_slice_idle;
2045 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2046 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
2047 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2048 group_idle ? 1 : 0);
2052 * Move request from internal lists to the request queue dispatch list.
2054 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2056 struct cfq_data *cfqd = q->elevator->elevator_data;
2057 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2059 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2061 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2062 cfq_remove_request(rq);
2064 (RQ_CFQG(rq))->dispatched++;
2065 elv_dispatch_sort(q, rq);
2067 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2068 cfqq->nr_sectors += blk_rq_sectors(rq);
2069 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2070 rq_data_dir(rq), rq_is_sync(rq));
2074 * return expired entry, or NULL to just start from scratch in rbtree
2076 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2078 struct request *rq = NULL;
2080 if (cfq_cfqq_fifo_expire(cfqq))
2083 cfq_mark_cfqq_fifo_expire(cfqq);
2085 if (list_empty(&cfqq->fifo))
2088 rq = rq_entry_fifo(cfqq->fifo.next);
2089 if (time_before(jiffies, rq_fifo_time(rq)))
2092 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2097 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2099 const int base_rq = cfqd->cfq_slice_async_rq;
2101 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2103 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2107 * Must be called with the queue_lock held.
2109 static int cfqq_process_refs(struct cfq_queue *cfqq)
2111 int process_refs, io_refs;
2113 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2114 process_refs = cfqq->ref - io_refs;
2115 BUG_ON(process_refs < 0);
2116 return process_refs;
2119 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2121 int process_refs, new_process_refs;
2122 struct cfq_queue *__cfqq;
2125 * If there are no process references on the new_cfqq, then it is
2126 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2127 * chain may have dropped their last reference (not just their
2128 * last process reference).
2130 if (!cfqq_process_refs(new_cfqq))
2133 /* Avoid a circular list and skip interim queue merges */
2134 while ((__cfqq = new_cfqq->new_cfqq)) {
2140 process_refs = cfqq_process_refs(cfqq);
2141 new_process_refs = cfqq_process_refs(new_cfqq);
2143 * If the process for the cfqq has gone away, there is no
2144 * sense in merging the queues.
2146 if (process_refs == 0 || new_process_refs == 0)
2150 * Merge in the direction of the lesser amount of work.
2152 if (new_process_refs >= process_refs) {
2153 cfqq->new_cfqq = new_cfqq;
2154 new_cfqq->ref += process_refs;
2156 new_cfqq->new_cfqq = cfqq;
2157 cfqq->ref += new_process_refs;
2161 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2162 struct cfq_group *cfqg, enum wl_prio_t prio)
2164 struct cfq_queue *queue;
2166 bool key_valid = false;
2167 unsigned long lowest_key = 0;
2168 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2170 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2171 /* select the one with lowest rb_key */
2172 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2174 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2175 lowest_key = queue->rb_key;
2184 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2188 struct cfq_rb_root *st;
2189 unsigned group_slice;
2190 enum wl_prio_t original_prio = cfqd->serving_prio;
2192 /* Choose next priority. RT > BE > IDLE */
2193 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2194 cfqd->serving_prio = RT_WORKLOAD;
2195 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2196 cfqd->serving_prio = BE_WORKLOAD;
2198 cfqd->serving_prio = IDLE_WORKLOAD;
2199 cfqd->workload_expires = jiffies + 1;
2203 if (original_prio != cfqd->serving_prio)
2207 * For RT and BE, we have to choose also the type
2208 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2211 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2215 * check workload expiration, and that we still have other queues ready
2217 if (count && !time_after(jiffies, cfqd->workload_expires))
2221 /* otherwise select new workload type */
2222 cfqd->serving_type =
2223 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2224 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2228 * the workload slice is computed as a fraction of target latency
2229 * proportional to the number of queues in that workload, over
2230 * all the queues in the same priority class
2232 group_slice = cfq_group_slice(cfqd, cfqg);
2234 slice = group_slice * count /
2235 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2236 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2238 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2242 * Async queues are currently system wide. Just taking
2243 * proportion of queues with-in same group will lead to higher
2244 * async ratio system wide as generally root group is going
2245 * to have higher weight. A more accurate thing would be to
2246 * calculate system wide asnc/sync ratio.
2248 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2249 tmp = tmp/cfqd->busy_queues;
2250 slice = min_t(unsigned, slice, tmp);
2252 /* async workload slice is scaled down according to
2253 * the sync/async slice ratio. */
2254 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2256 /* sync workload slice is at least 2 * cfq_slice_idle */
2257 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2259 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2260 cfq_log(cfqd, "workload slice:%d", slice);
2261 cfqd->workload_expires = jiffies + slice;
2264 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2266 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2267 struct cfq_group *cfqg;
2269 if (RB_EMPTY_ROOT(&st->rb))
2271 cfqg = cfq_rb_first_group(st);
2272 update_min_vdisktime(st);
2276 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2278 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2280 cfqd->serving_group = cfqg;
2282 /* Restore the workload type data */
2283 if (cfqg->saved_workload_slice) {
2284 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2285 cfqd->serving_type = cfqg->saved_workload;
2286 cfqd->serving_prio = cfqg->saved_serving_prio;
2288 cfqd->workload_expires = jiffies - 1;
2290 choose_service_tree(cfqd, cfqg);
2294 * Select a queue for service. If we have a current active queue,
2295 * check whether to continue servicing it, or retrieve and set a new one.
2297 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2299 struct cfq_queue *cfqq, *new_cfqq = NULL;
2301 cfqq = cfqd->active_queue;
2305 if (!cfqd->rq_queued)
2309 * We were waiting for group to get backlogged. Expire the queue
2311 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2315 * The active queue has run out of time, expire it and select new.
2317 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2319 * If slice had not expired at the completion of last request
2320 * we might not have turned on wait_busy flag. Don't expire
2321 * the queue yet. Allow the group to get backlogged.
2323 * The very fact that we have used the slice, that means we
2324 * have been idling all along on this queue and it should be
2325 * ok to wait for this request to complete.
2327 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2328 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2332 goto check_group_idle;
2336 * The active queue has requests and isn't expired, allow it to
2339 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2343 * If another queue has a request waiting within our mean seek
2344 * distance, let it run. The expire code will check for close
2345 * cooperators and put the close queue at the front of the service
2346 * tree. If possible, merge the expiring queue with the new cfqq.
2348 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2350 if (!cfqq->new_cfqq)
2351 cfq_setup_merge(cfqq, new_cfqq);
2356 * No requests pending. If the active queue still has requests in
2357 * flight or is idling for a new request, allow either of these
2358 * conditions to happen (or time out) before selecting a new queue.
2360 if (timer_pending(&cfqd->idle_slice_timer)) {
2366 * This is a deep seek queue, but the device is much faster than
2367 * the queue can deliver, don't idle
2369 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2370 (cfq_cfqq_slice_new(cfqq) ||
2371 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2372 cfq_clear_cfqq_deep(cfqq);
2373 cfq_clear_cfqq_idle_window(cfqq);
2376 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2382 * If group idle is enabled and there are requests dispatched from
2383 * this group, wait for requests to complete.
2386 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2387 cfqq->cfqg->dispatched &&
2388 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2394 cfq_slice_expired(cfqd, 0);
2397 * Current queue expired. Check if we have to switch to a new
2401 cfq_choose_cfqg(cfqd);
2403 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2408 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2412 while (cfqq->next_rq) {
2413 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2417 BUG_ON(!list_empty(&cfqq->fifo));
2419 /* By default cfqq is not expired if it is empty. Do it explicitly */
2420 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2425 * Drain our current requests. Used for barriers and when switching
2426 * io schedulers on-the-fly.
2428 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2430 struct cfq_queue *cfqq;
2433 /* Expire the timeslice of the current active queue first */
2434 cfq_slice_expired(cfqd, 0);
2435 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2436 __cfq_set_active_queue(cfqd, cfqq);
2437 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2440 BUG_ON(cfqd->busy_queues);
2442 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2446 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2447 struct cfq_queue *cfqq)
2449 /* the queue hasn't finished any request, can't estimate */
2450 if (cfq_cfqq_slice_new(cfqq))
2452 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2459 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2461 unsigned int max_dispatch;
2464 * Drain async requests before we start sync IO
2466 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2470 * If this is an async queue and we have sync IO in flight, let it wait
2472 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2475 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2476 if (cfq_class_idle(cfqq))
2480 * Does this cfqq already have too much IO in flight?
2482 if (cfqq->dispatched >= max_dispatch) {
2483 bool promote_sync = false;
2485 * idle queue must always only have a single IO in flight
2487 if (cfq_class_idle(cfqq))
2491 * If there is only one sync queue
2492 * we can ignore async queue here and give the sync
2493 * queue no dispatch limit. The reason is a sync queue can
2494 * preempt async queue, limiting the sync queue doesn't make
2495 * sense. This is useful for aiostress test.
2497 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2498 promote_sync = true;
2501 * We have other queues, don't allow more IO from this one
2503 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2508 * Sole queue user, no limit
2510 if (cfqd->busy_queues == 1 || promote_sync)
2514 * Normally we start throttling cfqq when cfq_quantum/2
2515 * requests have been dispatched. But we can drive
2516 * deeper queue depths at the beginning of slice
2517 * subjected to upper limit of cfq_quantum.
2519 max_dispatch = cfqd->cfq_quantum;
2523 * Async queues must wait a bit before being allowed dispatch.
2524 * We also ramp up the dispatch depth gradually for async IO,
2525 * based on the last sync IO we serviced
2527 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2528 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2531 depth = last_sync / cfqd->cfq_slice[1];
2532 if (!depth && !cfqq->dispatched)
2534 if (depth < max_dispatch)
2535 max_dispatch = depth;
2539 * If we're below the current max, allow a dispatch
2541 return cfqq->dispatched < max_dispatch;
2545 * Dispatch a request from cfqq, moving them to the request queue
2548 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2552 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2554 if (!cfq_may_dispatch(cfqd, cfqq))
2558 * follow expired path, else get first next available
2560 rq = cfq_check_fifo(cfqq);
2565 * insert request into driver dispatch list
2567 cfq_dispatch_insert(cfqd->queue, rq);
2569 if (!cfqd->active_cic) {
2570 struct cfq_io_context *cic = RQ_CIC(rq);
2572 atomic_long_inc(&cic->ioc->refcount);
2573 cfqd->active_cic = cic;
2580 * Find the cfqq that we need to service and move a request from that to the
2583 static int cfq_dispatch_requests(struct request_queue *q, int force)
2585 struct cfq_data *cfqd = q->elevator->elevator_data;
2586 struct cfq_queue *cfqq;
2588 if (!cfqd->busy_queues)
2591 if (unlikely(force))
2592 return cfq_forced_dispatch(cfqd);
2594 cfqq = cfq_select_queue(cfqd);
2599 * Dispatch a request from this cfqq, if it is allowed
2601 if (!cfq_dispatch_request(cfqd, cfqq))
2604 cfqq->slice_dispatch++;
2605 cfq_clear_cfqq_must_dispatch(cfqq);
2608 * expire an async queue immediately if it has used up its slice. idle
2609 * queue always expire after 1 dispatch round.
2611 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2612 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2613 cfq_class_idle(cfqq))) {
2614 cfqq->slice_end = jiffies + 1;
2615 cfq_slice_expired(cfqd, 0);
2618 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2623 * task holds one reference to the queue, dropped when task exits. each rq
2624 * in-flight on this queue also holds a reference, dropped when rq is freed.
2626 * Each cfq queue took a reference on the parent group. Drop it now.
2627 * queue lock must be held here.
2629 static void cfq_put_queue(struct cfq_queue *cfqq)
2631 struct cfq_data *cfqd = cfqq->cfqd;
2632 struct cfq_group *cfqg;
2634 BUG_ON(cfqq->ref <= 0);
2640 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2641 BUG_ON(rb_first(&cfqq->sort_list));
2642 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2645 if (unlikely(cfqd->active_queue == cfqq)) {
2646 __cfq_slice_expired(cfqd, cfqq, 0);
2647 cfq_schedule_dispatch(cfqd);
2650 BUG_ON(cfq_cfqq_on_rr(cfqq));
2651 kmem_cache_free(cfq_pool, cfqq);
2655 static void cfq_cic_free_rcu(struct rcu_head *head)
2657 kmem_cache_free(cfq_ioc_pool,
2658 container_of(head, struct cfq_io_context, rcu_head));
2661 static void cfq_cic_free(struct cfq_io_context *cic)
2663 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2666 static void cfq_release_cic(struct cfq_io_context *cic)
2668 struct io_context *ioc = cic->ioc;
2670 radix_tree_delete(&ioc->radix_root, cic->q->id);
2671 hlist_del(&cic->cic_list);
2675 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2677 struct cfq_queue *__cfqq, *next;
2680 * If this queue was scheduled to merge with another queue, be
2681 * sure to drop the reference taken on that queue (and others in
2682 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2684 __cfqq = cfqq->new_cfqq;
2686 if (__cfqq == cfqq) {
2687 WARN(1, "cfqq->new_cfqq loop detected\n");
2690 next = __cfqq->new_cfqq;
2691 cfq_put_queue(__cfqq);
2696 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2698 if (unlikely(cfqq == cfqd->active_queue)) {
2699 __cfq_slice_expired(cfqd, cfqq, 0);
2700 cfq_schedule_dispatch(cfqd);
2703 cfq_put_cooperator(cfqq);
2705 cfq_put_queue(cfqq);
2708 static void cfq_exit_cic(struct cfq_io_context *cic)
2710 struct cfq_data *cfqd = cic_to_cfqd(cic);
2711 struct io_context *ioc = cic->ioc;
2713 list_del_init(&cic->queue_list);
2716 * Both setting lookup hint to and clearing it from @cic are done
2717 * under queue_lock. If it's not pointing to @cic now, it never
2718 * will. Hint assignment itself can race safely.
2720 if (rcu_dereference_raw(ioc->ioc_data) == cic)
2721 rcu_assign_pointer(ioc->ioc_data, NULL);
2723 if (cic->cfqq[BLK_RW_ASYNC]) {
2724 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2725 cic->cfqq[BLK_RW_ASYNC] = NULL;
2728 if (cic->cfqq[BLK_RW_SYNC]) {
2729 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2730 cic->cfqq[BLK_RW_SYNC] = NULL;
2734 static struct cfq_io_context *
2735 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2737 struct cfq_io_context *cic;
2739 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2742 cic->ttime.last_end_request = jiffies;
2743 INIT_LIST_HEAD(&cic->queue_list);
2744 INIT_HLIST_NODE(&cic->cic_list);
2745 cic->exit = cfq_exit_cic;
2746 cic->release = cfq_release_cic;
2752 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2754 struct task_struct *tsk = current;
2757 if (!cfq_cfqq_prio_changed(cfqq))
2760 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2761 switch (ioprio_class) {
2763 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2764 case IOPRIO_CLASS_NONE:
2766 * no prio set, inherit CPU scheduling settings
2768 cfqq->ioprio = task_nice_ioprio(tsk);
2769 cfqq->ioprio_class = task_nice_ioclass(tsk);
2771 case IOPRIO_CLASS_RT:
2772 cfqq->ioprio = task_ioprio(ioc);
2773 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2775 case IOPRIO_CLASS_BE:
2776 cfqq->ioprio = task_ioprio(ioc);
2777 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2779 case IOPRIO_CLASS_IDLE:
2780 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2782 cfq_clear_cfqq_idle_window(cfqq);
2787 * keep track of original prio settings in case we have to temporarily
2788 * elevate the priority of this queue
2790 cfqq->org_ioprio = cfqq->ioprio;
2791 cfq_clear_cfqq_prio_changed(cfqq);
2794 static void changed_ioprio(struct cfq_io_context *cic)
2796 struct cfq_data *cfqd = cic_to_cfqd(cic);
2797 struct cfq_queue *cfqq;
2799 if (unlikely(!cfqd))
2802 cfqq = cic->cfqq[BLK_RW_ASYNC];
2804 struct cfq_queue *new_cfqq;
2805 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2808 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2809 cfq_put_queue(cfqq);
2813 cfqq = cic->cfqq[BLK_RW_SYNC];
2815 cfq_mark_cfqq_prio_changed(cfqq);
2818 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2819 pid_t pid, bool is_sync)
2821 RB_CLEAR_NODE(&cfqq->rb_node);
2822 RB_CLEAR_NODE(&cfqq->p_node);
2823 INIT_LIST_HEAD(&cfqq->fifo);
2828 cfq_mark_cfqq_prio_changed(cfqq);
2831 if (!cfq_class_idle(cfqq))
2832 cfq_mark_cfqq_idle_window(cfqq);
2833 cfq_mark_cfqq_sync(cfqq);
2838 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2839 static void changed_cgroup(struct cfq_io_context *cic)
2841 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2842 struct cfq_data *cfqd = cic_to_cfqd(cic);
2843 struct request_queue *q;
2845 if (unlikely(!cfqd))
2852 * Drop reference to sync queue. A new sync queue will be
2853 * assigned in new group upon arrival of a fresh request.
2855 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2856 cic_set_cfqq(cic, NULL, 1);
2857 cfq_put_queue(sync_cfqq);
2860 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2862 static struct cfq_queue *
2863 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2864 struct io_context *ioc, gfp_t gfp_mask)
2866 struct cfq_queue *cfqq, *new_cfqq = NULL;
2867 struct cfq_io_context *cic;
2868 struct cfq_group *cfqg;
2871 cfqg = cfq_get_cfqg(cfqd);
2872 cic = cfq_cic_lookup(cfqd, ioc);
2873 /* cic always exists here */
2874 cfqq = cic_to_cfqq(cic, is_sync);
2877 * Always try a new alloc if we fell back to the OOM cfqq
2878 * originally, since it should just be a temporary situation.
2880 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2885 } else if (gfp_mask & __GFP_WAIT) {
2886 spin_unlock_irq(cfqd->queue->queue_lock);
2887 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2888 gfp_mask | __GFP_ZERO,
2890 spin_lock_irq(cfqd->queue->queue_lock);
2894 cfqq = kmem_cache_alloc_node(cfq_pool,
2895 gfp_mask | __GFP_ZERO,
2900 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2901 cfq_init_prio_data(cfqq, ioc);
2902 cfq_link_cfqq_cfqg(cfqq, cfqg);
2903 cfq_log_cfqq(cfqd, cfqq, "alloced");
2905 cfqq = &cfqd->oom_cfqq;
2909 kmem_cache_free(cfq_pool, new_cfqq);
2914 static struct cfq_queue **
2915 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2917 switch (ioprio_class) {
2918 case IOPRIO_CLASS_RT:
2919 return &cfqd->async_cfqq[0][ioprio];
2920 case IOPRIO_CLASS_BE:
2921 return &cfqd->async_cfqq[1][ioprio];
2922 case IOPRIO_CLASS_IDLE:
2923 return &cfqd->async_idle_cfqq;
2929 static struct cfq_queue *
2930 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2933 const int ioprio = task_ioprio(ioc);
2934 const int ioprio_class = task_ioprio_class(ioc);
2935 struct cfq_queue **async_cfqq = NULL;
2936 struct cfq_queue *cfqq = NULL;
2939 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2944 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2947 * pin the queue now that it's allocated, scheduler exit will prune it
2949 if (!is_sync && !(*async_cfqq)) {
2959 * cfq_cic_lookup - lookup cfq_io_context
2960 * @cfqd: the associated cfq_data
2961 * @ioc: the associated io_context
2963 * Look up cfq_io_context associated with @cfqd - @ioc pair. Must be
2964 * called with queue_lock held.
2966 static struct cfq_io_context *
2967 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
2969 struct request_queue *q = cfqd->queue;
2970 struct cfq_io_context *cic;
2972 lockdep_assert_held(cfqd->queue->queue_lock);
2977 * cic's are indexed from @ioc using radix tree and hint pointer,
2978 * both of which are protected with RCU. All removals are done
2979 * holding both q and ioc locks, and we're holding q lock - if we
2980 * find a cic which points to us, it's guaranteed to be valid.
2983 cic = rcu_dereference(ioc->ioc_data);
2984 if (cic && cic->q == q)
2987 cic = radix_tree_lookup(&ioc->radix_root, cfqd->queue->id);
2988 if (cic && cic->q == q)
2989 rcu_assign_pointer(ioc->ioc_data, cic); /* allowed to race */
2998 * cfq_create_cic - create and link a cfq_io_context
2999 * @cfqd: cfqd of interest
3000 * @gfp_mask: allocation mask
3002 * Make sure cfq_io_context linking %current->io_context and @cfqd exists.
3003 * If ioc and/or cic doesn't exist, they will be created using @gfp_mask.
3005 static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
3007 struct request_queue *q = cfqd->queue;
3008 struct cfq_io_context *cic = NULL;
3009 struct io_context *ioc;
3012 might_sleep_if(gfp_mask & __GFP_WAIT);
3014 /* allocate stuff */
3015 ioc = create_io_context(current, gfp_mask, q->node);
3019 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3023 ret = radix_tree_preload(gfp_mask);
3028 cic->q = cfqd->queue;
3030 /* lock both q and ioc and try to link @cic */
3031 spin_lock_irq(q->queue_lock);
3032 spin_lock(&ioc->lock);
3034 ret = radix_tree_insert(&ioc->radix_root, q->id, cic);
3036 hlist_add_head(&cic->cic_list, &ioc->cic_list);
3037 list_add(&cic->queue_list, &cfqd->cic_list);
3039 } else if (ret == -EEXIST) {
3040 /* someone else already did it */
3044 spin_unlock(&ioc->lock);
3045 spin_unlock_irq(q->queue_lock);
3047 radix_tree_preload_end();
3050 printk(KERN_ERR "cfq: cic link failed!\n");
3057 * cfq_get_io_context - acquire cfq_io_context and bump refcnt on io_context
3058 * @cfqd: cfqd to setup cic for
3059 * @gfp_mask: allocation mask
3061 * Return cfq_io_context associating @cfqd and %current->io_context and
3062 * bump refcnt on io_context. If ioc or cic doesn't exist, they're created
3065 * Must be called under queue_lock which may be released and re-acquired.
3066 * This function also may sleep depending on @gfp_mask.
3068 static struct cfq_io_context *
3069 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3071 struct request_queue *q = cfqd->queue;
3072 struct cfq_io_context *cic = NULL;
3073 struct io_context *ioc;
3076 lockdep_assert_held(q->queue_lock);
3080 ioc = current->io_context;
3082 cic = cfq_cic_lookup(cfqd, ioc);
3087 /* slow path - unlock, create missing ones and retry */
3088 spin_unlock_irq(q->queue_lock);
3089 err = cfq_create_cic(cfqd, gfp_mask);
3090 spin_lock_irq(q->queue_lock);
3095 /* bump @ioc's refcnt and handle changed notifications */
3096 get_io_context(ioc);
3098 if (unlikely(cic->changed)) {
3099 if (test_and_clear_bit(CIC_IOPRIO_CHANGED, &cic->changed))
3100 changed_ioprio(cic);
3101 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3102 if (test_and_clear_bit(CIC_CGROUP_CHANGED, &cic->changed))
3103 changed_cgroup(cic);
3111 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3113 unsigned long elapsed = jiffies - ttime->last_end_request;
3114 elapsed = min(elapsed, 2UL * slice_idle);
3116 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3117 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3118 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3122 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3123 struct cfq_io_context *cic)
3125 if (cfq_cfqq_sync(cfqq)) {
3126 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3127 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3128 cfqd->cfq_slice_idle);
3130 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3131 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3136 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3140 sector_t n_sec = blk_rq_sectors(rq);
3141 if (cfqq->last_request_pos) {
3142 if (cfqq->last_request_pos < blk_rq_pos(rq))
3143 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3145 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3148 cfqq->seek_history <<= 1;
3149 if (blk_queue_nonrot(cfqd->queue))
3150 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3152 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3156 * Disable idle window if the process thinks too long or seeks so much that
3160 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3161 struct cfq_io_context *cic)
3163 int old_idle, enable_idle;
3166 * Don't idle for async or idle io prio class
3168 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3171 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3173 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3174 cfq_mark_cfqq_deep(cfqq);
3176 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3178 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3179 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3181 else if (sample_valid(cic->ttime.ttime_samples)) {
3182 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3188 if (old_idle != enable_idle) {
3189 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3191 cfq_mark_cfqq_idle_window(cfqq);
3193 cfq_clear_cfqq_idle_window(cfqq);
3198 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3199 * no or if we aren't sure, a 1 will cause a preempt.
3202 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3205 struct cfq_queue *cfqq;
3207 cfqq = cfqd->active_queue;
3211 if (cfq_class_idle(new_cfqq))
3214 if (cfq_class_idle(cfqq))
3218 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3220 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3224 * if the new request is sync, but the currently running queue is
3225 * not, let the sync request have priority.
3227 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3230 if (new_cfqq->cfqg != cfqq->cfqg)
3233 if (cfq_slice_used(cfqq))
3236 /* Allow preemption only if we are idling on sync-noidle tree */
3237 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3238 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3239 new_cfqq->service_tree->count == 2 &&
3240 RB_EMPTY_ROOT(&cfqq->sort_list))
3244 * So both queues are sync. Let the new request get disk time if
3245 * it's a metadata request and the current queue is doing regular IO.
3247 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3251 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3253 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3256 /* An idle queue should not be idle now for some reason */
3257 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3260 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3264 * if this request is as-good as one we would expect from the
3265 * current cfqq, let it preempt
3267 if (cfq_rq_close(cfqd, cfqq, rq))
3274 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3275 * let it have half of its nominal slice.
3277 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3279 struct cfq_queue *old_cfqq = cfqd->active_queue;
3281 cfq_log_cfqq(cfqd, cfqq, "preempt");
3282 cfq_slice_expired(cfqd, 1);
3285 * workload type is changed, don't save slice, otherwise preempt
3288 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3289 cfqq->cfqg->saved_workload_slice = 0;
3292 * Put the new queue at the front of the of the current list,
3293 * so we know that it will be selected next.
3295 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3297 cfq_service_tree_add(cfqd, cfqq, 1);
3299 cfqq->slice_end = 0;
3300 cfq_mark_cfqq_slice_new(cfqq);
3304 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3305 * something we should do about it
3308 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3311 struct cfq_io_context *cic = RQ_CIC(rq);
3314 if (rq->cmd_flags & REQ_PRIO)
3315 cfqq->prio_pending++;
3317 cfq_update_io_thinktime(cfqd, cfqq, cic);
3318 cfq_update_io_seektime(cfqd, cfqq, rq);
3319 cfq_update_idle_window(cfqd, cfqq, cic);
3321 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3323 if (cfqq == cfqd->active_queue) {
3325 * Remember that we saw a request from this process, but
3326 * don't start queuing just yet. Otherwise we risk seeing lots
3327 * of tiny requests, because we disrupt the normal plugging
3328 * and merging. If the request is already larger than a single
3329 * page, let it rip immediately. For that case we assume that
3330 * merging is already done. Ditto for a busy system that
3331 * has other work pending, don't risk delaying until the
3332 * idle timer unplug to continue working.
3334 if (cfq_cfqq_wait_request(cfqq)) {
3335 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3336 cfqd->busy_queues > 1) {
3337 cfq_del_timer(cfqd, cfqq);
3338 cfq_clear_cfqq_wait_request(cfqq);
3339 __blk_run_queue(cfqd->queue);
3341 cfq_blkiocg_update_idle_time_stats(
3343 cfq_mark_cfqq_must_dispatch(cfqq);
3346 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3348 * not the active queue - expire current slice if it is
3349 * idle and has expired it's mean thinktime or this new queue
3350 * has some old slice time left and is of higher priority or
3351 * this new queue is RT and the current one is BE
3353 cfq_preempt_queue(cfqd, cfqq);
3354 __blk_run_queue(cfqd->queue);
3358 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3360 struct cfq_data *cfqd = q->elevator->elevator_data;
3361 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3363 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3364 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3366 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3367 list_add_tail(&rq->queuelist, &cfqq->fifo);
3369 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3370 &cfqd->serving_group->blkg, rq_data_dir(rq),
3372 cfq_rq_enqueued(cfqd, cfqq, rq);
3376 * Update hw_tag based on peak queue depth over 50 samples under
3379 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3381 struct cfq_queue *cfqq = cfqd->active_queue;
3383 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3384 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3386 if (cfqd->hw_tag == 1)
3389 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3390 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3394 * If active queue hasn't enough requests and can idle, cfq might not
3395 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3398 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3399 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3400 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3403 if (cfqd->hw_tag_samples++ < 50)
3406 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3412 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3414 struct cfq_io_context *cic = cfqd->active_cic;
3416 /* If the queue already has requests, don't wait */
3417 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3420 /* If there are other queues in the group, don't wait */
3421 if (cfqq->cfqg->nr_cfqq > 1)
3424 /* the only queue in the group, but think time is big */
3425 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3428 if (cfq_slice_used(cfqq))
3431 /* if slice left is less than think time, wait busy */
3432 if (cic && sample_valid(cic->ttime.ttime_samples)
3433 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3437 * If think times is less than a jiffy than ttime_mean=0 and above
3438 * will not be true. It might happen that slice has not expired yet
3439 * but will expire soon (4-5 ns) during select_queue(). To cover the
3440 * case where think time is less than a jiffy, mark the queue wait
3441 * busy if only 1 jiffy is left in the slice.
3443 if (cfqq->slice_end - jiffies == 1)
3449 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3451 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3452 struct cfq_data *cfqd = cfqq->cfqd;
3453 const int sync = rq_is_sync(rq);
3457 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3458 !!(rq->cmd_flags & REQ_NOIDLE));
3460 cfq_update_hw_tag(cfqd);
3462 WARN_ON(!cfqd->rq_in_driver);
3463 WARN_ON(!cfqq->dispatched);
3464 cfqd->rq_in_driver--;
3466 (RQ_CFQG(rq))->dispatched--;
3467 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3468 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3469 rq_data_dir(rq), rq_is_sync(rq));
3471 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3474 struct cfq_rb_root *service_tree;
3476 RQ_CIC(rq)->ttime.last_end_request = now;
3478 if (cfq_cfqq_on_rr(cfqq))
3479 service_tree = cfqq->service_tree;
3481 service_tree = service_tree_for(cfqq->cfqg,
3482 cfqq_prio(cfqq), cfqq_type(cfqq));
3483 service_tree->ttime.last_end_request = now;
3484 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3485 cfqd->last_delayed_sync = now;
3488 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3489 cfqq->cfqg->ttime.last_end_request = now;
3493 * If this is the active queue, check if it needs to be expired,
3494 * or if we want to idle in case it has no pending requests.
3496 if (cfqd->active_queue == cfqq) {
3497 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3499 if (cfq_cfqq_slice_new(cfqq)) {
3500 cfq_set_prio_slice(cfqd, cfqq);
3501 cfq_clear_cfqq_slice_new(cfqq);
3505 * Should we wait for next request to come in before we expire
3508 if (cfq_should_wait_busy(cfqd, cfqq)) {
3509 unsigned long extend_sl = cfqd->cfq_slice_idle;
3510 if (!cfqd->cfq_slice_idle)
3511 extend_sl = cfqd->cfq_group_idle;
3512 cfqq->slice_end = jiffies + extend_sl;
3513 cfq_mark_cfqq_wait_busy(cfqq);
3514 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3518 * Idling is not enabled on:
3520 * - idle-priority queues
3522 * - queues with still some requests queued
3523 * - when there is a close cooperator
3525 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3526 cfq_slice_expired(cfqd, 1);
3527 else if (sync && cfqq_empty &&
3528 !cfq_close_cooperator(cfqd, cfqq)) {
3529 cfq_arm_slice_timer(cfqd);
3533 if (!cfqd->rq_in_driver)
3534 cfq_schedule_dispatch(cfqd);
3537 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3539 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3540 cfq_mark_cfqq_must_alloc_slice(cfqq);
3541 return ELV_MQUEUE_MUST;
3544 return ELV_MQUEUE_MAY;
3547 static int cfq_may_queue(struct request_queue *q, int rw)
3549 struct cfq_data *cfqd = q->elevator->elevator_data;
3550 struct task_struct *tsk = current;
3551 struct cfq_io_context *cic;
3552 struct cfq_queue *cfqq;
3555 * don't force setup of a queue from here, as a call to may_queue
3556 * does not necessarily imply that a request actually will be queued.
3557 * so just lookup a possibly existing queue, or return 'may queue'
3560 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3562 return ELV_MQUEUE_MAY;
3564 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3566 cfq_init_prio_data(cfqq, cic->ioc);
3568 return __cfq_may_queue(cfqq);
3571 return ELV_MQUEUE_MAY;
3575 * queue lock held here
3577 static void cfq_put_request(struct request *rq)
3579 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3582 const int rw = rq_data_dir(rq);
3584 BUG_ON(!cfqq->allocated[rw]);
3585 cfqq->allocated[rw]--;
3587 put_io_context(RQ_CIC(rq)->ioc, cfqq->cfqd->queue);
3589 rq->elevator_private[0] = NULL;
3590 rq->elevator_private[1] = NULL;
3592 /* Put down rq reference on cfqg */
3593 cfq_put_cfqg(RQ_CFQG(rq));
3594 rq->elevator_private[2] = NULL;
3596 cfq_put_queue(cfqq);
3600 static struct cfq_queue *
3601 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3602 struct cfq_queue *cfqq)
3604 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3605 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3606 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3607 cfq_put_queue(cfqq);
3608 return cic_to_cfqq(cic, 1);
3612 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3613 * was the last process referring to said cfqq.
3615 static struct cfq_queue *
3616 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3618 if (cfqq_process_refs(cfqq) == 1) {
3619 cfqq->pid = current->pid;
3620 cfq_clear_cfqq_coop(cfqq);
3621 cfq_clear_cfqq_split_coop(cfqq);
3625 cic_set_cfqq(cic, NULL, 1);
3627 cfq_put_cooperator(cfqq);
3629 cfq_put_queue(cfqq);
3633 * Allocate cfq data structures associated with this request.
3636 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3638 struct cfq_data *cfqd = q->elevator->elevator_data;
3639 struct cfq_io_context *cic;
3640 const int rw = rq_data_dir(rq);
3641 const bool is_sync = rq_is_sync(rq);
3642 struct cfq_queue *cfqq;
3644 might_sleep_if(gfp_mask & __GFP_WAIT);
3646 spin_lock_irq(q->queue_lock);
3647 cic = cfq_get_io_context(cfqd, gfp_mask);
3652 cfqq = cic_to_cfqq(cic, is_sync);
3653 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3654 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3655 cic_set_cfqq(cic, cfqq, is_sync);
3658 * If the queue was seeky for too long, break it apart.
3660 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3661 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3662 cfqq = split_cfqq(cic, cfqq);
3668 * Check to see if this queue is scheduled to merge with
3669 * another, closely cooperating queue. The merging of
3670 * queues happens here as it must be done in process context.
3671 * The reference on new_cfqq was taken in merge_cfqqs.
3674 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3677 cfqq->allocated[rw]++;
3680 rq->elevator_private[0] = cic;
3681 rq->elevator_private[1] = cfqq;
3682 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3683 spin_unlock_irq(q->queue_lock);
3687 cfq_schedule_dispatch(cfqd);
3688 spin_unlock_irq(q->queue_lock);
3689 cfq_log(cfqd, "set_request fail");
3693 static void cfq_kick_queue(struct work_struct *work)
3695 struct cfq_data *cfqd =
3696 container_of(work, struct cfq_data, unplug_work);
3697 struct request_queue *q = cfqd->queue;
3699 spin_lock_irq(q->queue_lock);
3700 __blk_run_queue(cfqd->queue);
3701 spin_unlock_irq(q->queue_lock);
3705 * Timer running if the active_queue is currently idling inside its time slice
3707 static void cfq_idle_slice_timer(unsigned long data)
3709 struct cfq_data *cfqd = (struct cfq_data *) data;
3710 struct cfq_queue *cfqq;
3711 unsigned long flags;
3714 cfq_log(cfqd, "idle timer fired");
3716 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3718 cfqq = cfqd->active_queue;
3723 * We saw a request before the queue expired, let it through
3725 if (cfq_cfqq_must_dispatch(cfqq))
3731 if (cfq_slice_used(cfqq))
3735 * only expire and reinvoke request handler, if there are
3736 * other queues with pending requests
3738 if (!cfqd->busy_queues)
3742 * not expired and it has a request pending, let it dispatch
3744 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3748 * Queue depth flag is reset only when the idle didn't succeed
3750 cfq_clear_cfqq_deep(cfqq);
3753 cfq_slice_expired(cfqd, timed_out);
3755 cfq_schedule_dispatch(cfqd);
3757 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3760 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3762 del_timer_sync(&cfqd->idle_slice_timer);
3763 cancel_work_sync(&cfqd->unplug_work);
3766 static void cfq_put_async_queues(struct cfq_data *cfqd)
3770 for (i = 0; i < IOPRIO_BE_NR; i++) {
3771 if (cfqd->async_cfqq[0][i])
3772 cfq_put_queue(cfqd->async_cfqq[0][i]);
3773 if (cfqd->async_cfqq[1][i])
3774 cfq_put_queue(cfqd->async_cfqq[1][i]);
3777 if (cfqd->async_idle_cfqq)
3778 cfq_put_queue(cfqd->async_idle_cfqq);
3781 static void cfq_exit_queue(struct elevator_queue *e)
3783 struct cfq_data *cfqd = e->elevator_data;
3784 struct request_queue *q = cfqd->queue;
3787 cfq_shutdown_timer_wq(cfqd);
3789 spin_lock_irq(q->queue_lock);
3791 if (cfqd->active_queue)
3792 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3794 while (!list_empty(&cfqd->cic_list)) {
3795 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3796 struct cfq_io_context,
3798 struct io_context *ioc = cic->ioc;
3800 spin_lock(&ioc->lock);
3802 cfq_release_cic(cic);
3803 spin_unlock(&ioc->lock);
3806 cfq_put_async_queues(cfqd);
3807 cfq_release_cfq_groups(cfqd);
3810 * If there are groups which we could not unlink from blkcg list,
3811 * wait for a rcu period for them to be freed.
3813 if (cfqd->nr_blkcg_linked_grps)
3816 spin_unlock_irq(q->queue_lock);
3818 cfq_shutdown_timer_wq(cfqd);
3821 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3822 * Do this wait only if there are other unlinked groups out
3823 * there. This can happen if cgroup deletion path claimed the
3824 * responsibility of cleaning up a group before queue cleanup code
3827 * Do not call synchronize_rcu() unconditionally as there are drivers
3828 * which create/delete request queue hundreds of times during scan/boot
3829 * and synchronize_rcu() can take significant time and slow down boot.
3834 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3835 /* Free up per cpu stats for root group */
3836 free_percpu(cfqd->root_group.blkg.stats_cpu);
3841 static void *cfq_init_queue(struct request_queue *q)
3843 struct cfq_data *cfqd;
3845 struct cfq_group *cfqg;
3846 struct cfq_rb_root *st;
3848 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3852 /* Init root service tree */
3853 cfqd->grp_service_tree = CFQ_RB_ROOT;
3855 /* Init root group */
3856 cfqg = &cfqd->root_group;
3857 for_each_cfqg_st(cfqg, i, j, st)
3859 RB_CLEAR_NODE(&cfqg->rb_node);
3861 /* Give preference to root group over other groups */
3862 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3864 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3866 * Set root group reference to 2. One reference will be dropped when
3867 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3868 * Other reference will remain there as we don't want to delete this
3869 * group as it is statically allocated and gets destroyed when
3870 * throtl_data goes away.
3874 if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
3882 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3885 cfqd->nr_blkcg_linked_grps++;
3887 /* Add group on cfqd->cfqg_list */
3888 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
3891 * Not strictly needed (since RB_ROOT just clears the node and we
3892 * zeroed cfqd on alloc), but better be safe in case someone decides
3893 * to add magic to the rb code
3895 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3896 cfqd->prio_trees[i] = RB_ROOT;
3899 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3900 * Grab a permanent reference to it, so that the normal code flow
3901 * will not attempt to free it.
3903 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3904 cfqd->oom_cfqq.ref++;
3905 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3907 INIT_LIST_HEAD(&cfqd->cic_list);
3911 init_timer(&cfqd->idle_slice_timer);
3912 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3913 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3915 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3917 cfqd->cfq_quantum = cfq_quantum;
3918 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3919 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3920 cfqd->cfq_back_max = cfq_back_max;
3921 cfqd->cfq_back_penalty = cfq_back_penalty;
3922 cfqd->cfq_slice[0] = cfq_slice_async;
3923 cfqd->cfq_slice[1] = cfq_slice_sync;
3924 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3925 cfqd->cfq_slice_idle = cfq_slice_idle;
3926 cfqd->cfq_group_idle = cfq_group_idle;
3927 cfqd->cfq_latency = 1;
3930 * we optimistically start assuming sync ops weren't delayed in last
3931 * second, in order to have larger depth for async operations.
3933 cfqd->last_delayed_sync = jiffies - HZ;
3937 static void cfq_slab_kill(void)
3940 * Caller already ensured that pending RCU callbacks are completed,
3941 * so we should have no busy allocations at this point.
3944 kmem_cache_destroy(cfq_pool);
3946 kmem_cache_destroy(cfq_ioc_pool);
3949 static int __init cfq_slab_setup(void)
3951 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3955 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3966 * sysfs parts below -->
3969 cfq_var_show(unsigned int var, char *page)
3971 return sprintf(page, "%d\n", var);
3975 cfq_var_store(unsigned int *var, const char *page, size_t count)
3977 char *p = (char *) page;
3979 *var = simple_strtoul(p, &p, 10);
3983 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3984 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3986 struct cfq_data *cfqd = e->elevator_data; \
3987 unsigned int __data = __VAR; \
3989 __data = jiffies_to_msecs(__data); \
3990 return cfq_var_show(__data, (page)); \
3992 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3993 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3994 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3995 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3996 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3997 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3998 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
3999 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4000 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4001 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4002 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4003 #undef SHOW_FUNCTION
4005 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4006 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4008 struct cfq_data *cfqd = e->elevator_data; \
4009 unsigned int __data; \
4010 int ret = cfq_var_store(&__data, (page), count); \
4011 if (__data < (MIN)) \
4013 else if (__data > (MAX)) \
4016 *(__PTR) = msecs_to_jiffies(__data); \
4018 *(__PTR) = __data; \
4021 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4022 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4024 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4026 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4027 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4029 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4030 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4031 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4032 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4033 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4035 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4036 #undef STORE_FUNCTION
4038 #define CFQ_ATTR(name) \
4039 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4041 static struct elv_fs_entry cfq_attrs[] = {
4043 CFQ_ATTR(fifo_expire_sync),
4044 CFQ_ATTR(fifo_expire_async),
4045 CFQ_ATTR(back_seek_max),
4046 CFQ_ATTR(back_seek_penalty),
4047 CFQ_ATTR(slice_sync),
4048 CFQ_ATTR(slice_async),
4049 CFQ_ATTR(slice_async_rq),
4050 CFQ_ATTR(slice_idle),
4051 CFQ_ATTR(group_idle),
4052 CFQ_ATTR(low_latency),
4056 static struct elevator_type iosched_cfq = {
4058 .elevator_merge_fn = cfq_merge,
4059 .elevator_merged_fn = cfq_merged_request,
4060 .elevator_merge_req_fn = cfq_merged_requests,
4061 .elevator_allow_merge_fn = cfq_allow_merge,
4062 .elevator_bio_merged_fn = cfq_bio_merged,
4063 .elevator_dispatch_fn = cfq_dispatch_requests,
4064 .elevator_add_req_fn = cfq_insert_request,
4065 .elevator_activate_req_fn = cfq_activate_request,
4066 .elevator_deactivate_req_fn = cfq_deactivate_request,
4067 .elevator_completed_req_fn = cfq_completed_request,
4068 .elevator_former_req_fn = elv_rb_former_request,
4069 .elevator_latter_req_fn = elv_rb_latter_request,
4070 .elevator_set_req_fn = cfq_set_request,
4071 .elevator_put_req_fn = cfq_put_request,
4072 .elevator_may_queue_fn = cfq_may_queue,
4073 .elevator_init_fn = cfq_init_queue,
4074 .elevator_exit_fn = cfq_exit_queue,
4076 .elevator_attrs = cfq_attrs,
4077 .elevator_name = "cfq",
4078 .elevator_owner = THIS_MODULE,
4081 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4082 static struct blkio_policy_type blkio_policy_cfq = {
4084 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4085 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4087 .plid = BLKIO_POLICY_PROP,
4090 static struct blkio_policy_type blkio_policy_cfq;
4093 static int __init cfq_init(void)
4096 * could be 0 on HZ < 1000 setups
4098 if (!cfq_slice_async)
4099 cfq_slice_async = 1;
4100 if (!cfq_slice_idle)
4103 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4104 if (!cfq_group_idle)
4109 if (cfq_slab_setup())
4112 elv_register(&iosched_cfq);
4113 blkio_policy_register(&blkio_policy_cfq);
4118 static void __exit cfq_exit(void)
4120 blkio_policy_unregister(&blkio_policy_cfq);
4121 elv_unregister(&iosched_cfq);
4122 rcu_barrier(); /* make sure all cic RCU frees are complete */
4126 module_init(cfq_init);
4127 module_exit(cfq_exit);
4129 MODULE_AUTHOR("Jens Axboe");
4130 MODULE_LICENSE("GPL");
4131 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");