2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
22 /* max queue in one round of service */
23 static const int cfq_quantum = 8;
24 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max = 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty = 2;
29 static const int cfq_slice_sync = HZ / 10;
30 static int cfq_slice_async = HZ / 25;
31 static const int cfq_slice_async_rq = 2;
32 static int cfq_slice_idle = HZ / 125;
33 static int cfq_group_idle = HZ / 125;
34 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
35 static const int cfq_hist_divisor = 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 ((struct cfq_io_context *) (rq)->elevator_private[0])
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
61 static struct kmem_cache *cfq_pool;
62 static struct kmem_cache *cfq_ioc_pool;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
65 static struct completion *ioc_gone;
66 static DEFINE_SPINLOCK(ioc_gone_lock);
68 static DEFINE_SPINLOCK(cic_index_lock);
69 static DEFINE_IDA(cic_index_ida);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data *cfqd;
104 /* service_tree member */
105 struct rb_node rb_node;
106 /* service_tree key */
107 unsigned long rb_key;
108 /* prio tree member */
109 struct rb_node p_node;
110 /* prio tree root we belong to, if any */
111 struct rb_root *p_root;
112 /* sorted list of pending requests */
113 struct rb_root sort_list;
114 /* if fifo isn't expired, next request to serve */
115 struct request *next_rq;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start;
125 unsigned int allocated_slice;
126 unsigned int slice_dispatch;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start;
129 unsigned long slice_end;
132 /* pending metadata requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio, org_ioprio;
139 unsigned short ioprio_class, org_ioprio_class;
144 sector_t last_request_pos;
146 struct cfq_rb_root *service_tree;
147 struct cfq_queue *new_cfqq;
148 struct cfq_group *cfqg;
149 /* Number of sectors dispatched from queue in single dispatch round */
150 unsigned long nr_sectors;
154 * First index in the service_trees.
155 * IDLE is handled separately, so it has negative index
165 * Second index in the service_trees.
169 SYNC_NOIDLE_WORKLOAD = 1,
173 /* This is per cgroup per device grouping structure */
175 /* group service_tree member */
176 struct rb_node rb_node;
178 /* group service_tree key */
182 /* number of cfqq currently on this group */
186 * Per group busy queus average. Useful for workload slice calc. We
187 * create the array for each prio class but at run time it is used
188 * only for RT and BE class and slot for IDLE class remains unused.
189 * This is primarily done to avoid confusion and a gcc warning.
191 unsigned int busy_queues_avg[CFQ_PRIO_NR];
193 * rr lists of queues with requests. We maintain service trees for
194 * RT and BE classes. These trees are subdivided in subclasses
195 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
196 * class there is no subclassification and all the cfq queues go on
197 * a single tree service_tree_idle.
198 * Counts are embedded in the cfq_rb_root
200 struct cfq_rb_root service_trees[2][3];
201 struct cfq_rb_root service_tree_idle;
203 unsigned long saved_workload_slice;
204 enum wl_type_t saved_workload;
205 enum wl_prio_t saved_serving_prio;
206 struct blkio_group blkg;
207 #ifdef CONFIG_CFQ_GROUP_IOSCHED
208 struct hlist_node cfqd_node;
211 /* number of requests that are on the dispatch list or inside driver */
216 * Per block device queue structure
219 struct request_queue *queue;
220 /* Root service tree for cfq_groups */
221 struct cfq_rb_root grp_service_tree;
222 struct cfq_group root_group;
225 * The priority currently being served
227 enum wl_prio_t serving_prio;
228 enum wl_type_t serving_type;
229 unsigned long workload_expires;
230 struct cfq_group *serving_group;
233 * Each priority tree is sorted by next_request position. These
234 * trees are used when determining if two or more queues are
235 * interleaving requests (see cfq_close_cooperator).
237 struct rb_root prio_trees[CFQ_PRIO_LISTS];
239 unsigned int busy_queues;
240 unsigned int busy_sync_queues;
246 * queue-depth detection
252 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
253 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
256 int hw_tag_est_depth;
257 unsigned int hw_tag_samples;
260 * idle window management
262 struct timer_list idle_slice_timer;
263 struct work_struct unplug_work;
265 struct cfq_queue *active_queue;
266 struct cfq_io_context *active_cic;
269 * async queue for each priority case
271 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
272 struct cfq_queue *async_idle_cfqq;
274 sector_t last_position;
277 * tunables, see top of file
279 unsigned int cfq_quantum;
280 unsigned int cfq_fifo_expire[2];
281 unsigned int cfq_back_penalty;
282 unsigned int cfq_back_max;
283 unsigned int cfq_slice[2];
284 unsigned int cfq_slice_async_rq;
285 unsigned int cfq_slice_idle;
286 unsigned int cfq_group_idle;
287 unsigned int cfq_latency;
289 unsigned int cic_index;
290 struct list_head cic_list;
293 * Fallback dummy cfqq for extreme OOM conditions
295 struct cfq_queue oom_cfqq;
297 unsigned long last_delayed_sync;
299 /* List of cfq groups being managed on this device*/
300 struct hlist_head cfqg_list;
304 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
306 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
313 if (prio == IDLE_WORKLOAD)
314 return &cfqg->service_tree_idle;
316 return &cfqg->service_trees[prio][type];
319 enum cfqq_state_flags {
320 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
321 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
322 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
323 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
324 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
325 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
326 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
327 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
328 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
329 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
330 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
331 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
332 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
335 #define CFQ_CFQQ_FNS(name) \
336 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
338 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
340 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
342 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
344 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
346 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
350 CFQ_CFQQ_FNS(wait_request);
351 CFQ_CFQQ_FNS(must_dispatch);
352 CFQ_CFQQ_FNS(must_alloc_slice);
353 CFQ_CFQQ_FNS(fifo_expire);
354 CFQ_CFQQ_FNS(idle_window);
355 CFQ_CFQQ_FNS(prio_changed);
356 CFQ_CFQQ_FNS(slice_new);
359 CFQ_CFQQ_FNS(split_coop);
361 CFQ_CFQQ_FNS(wait_busy);
364 #ifdef CONFIG_CFQ_GROUP_IOSCHED
365 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
366 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
367 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
368 blkg_path(&(cfqq)->cfqg->blkg), ##args);
370 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
371 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
372 blkg_path(&(cfqg)->blkg), ##args); \
375 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
376 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
377 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
379 #define cfq_log(cfqd, fmt, args...) \
380 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
382 /* Traverses through cfq group service trees */
383 #define for_each_cfqg_st(cfqg, i, j, st) \
384 for (i = 0; i <= IDLE_WORKLOAD; i++) \
385 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
386 : &cfqg->service_tree_idle; \
387 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
388 (i == IDLE_WORKLOAD && j == 0); \
389 j++, st = i < IDLE_WORKLOAD ? \
390 &cfqg->service_trees[i][j]: NULL) \
393 static inline bool iops_mode(struct cfq_data *cfqd)
396 * If we are not idling on queues and it is a NCQ drive, parallel
397 * execution of requests is on and measuring time is not possible
398 * in most of the cases until and unless we drive shallower queue
399 * depths and that becomes a performance bottleneck. In such cases
400 * switch to start providing fairness in terms of number of IOs.
402 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
408 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
410 if (cfq_class_idle(cfqq))
411 return IDLE_WORKLOAD;
412 if (cfq_class_rt(cfqq))
418 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
420 if (!cfq_cfqq_sync(cfqq))
421 return ASYNC_WORKLOAD;
422 if (!cfq_cfqq_idle_window(cfqq))
423 return SYNC_NOIDLE_WORKLOAD;
424 return SYNC_WORKLOAD;
427 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
428 struct cfq_data *cfqd,
429 struct cfq_group *cfqg)
431 if (wl == IDLE_WORKLOAD)
432 return cfqg->service_tree_idle.count;
434 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
435 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
436 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
439 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
440 struct cfq_group *cfqg)
442 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
443 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
446 static void cfq_dispatch_insert(struct request_queue *, struct request *);
447 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
448 struct io_context *, gfp_t);
449 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
450 struct io_context *);
452 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
455 return cic->cfqq[is_sync];
458 static inline void cic_set_cfqq(struct cfq_io_context *cic,
459 struct cfq_queue *cfqq, bool is_sync)
461 cic->cfqq[is_sync] = cfqq;
464 #define CIC_DEAD_KEY 1ul
465 #define CIC_DEAD_INDEX_SHIFT 1
467 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
469 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
472 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
474 struct cfq_data *cfqd = cic->key;
476 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
483 * We regard a request as SYNC, if it's either a read or has the SYNC bit
484 * set (in which case it could also be direct WRITE).
486 static inline bool cfq_bio_sync(struct bio *bio)
488 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
492 * scheduler run of queue, if there are requests pending and no one in the
493 * driver that will restart queueing
495 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
497 if (cfqd->busy_queues) {
498 cfq_log(cfqd, "schedule dispatch");
499 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
503 static int cfq_queue_empty(struct request_queue *q)
505 struct cfq_data *cfqd = q->elevator->elevator_data;
507 return !cfqd->rq_queued;
511 * Scale schedule slice based on io priority. Use the sync time slice only
512 * if a queue is marked sync and has sync io queued. A sync queue with async
513 * io only, should not get full sync slice length.
515 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
518 const int base_slice = cfqd->cfq_slice[sync];
520 WARN_ON(prio >= IOPRIO_BE_NR);
522 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
526 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
528 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
531 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
533 u64 d = delta << CFQ_SERVICE_SHIFT;
535 d = d * BLKIO_WEIGHT_DEFAULT;
536 do_div(d, cfqg->weight);
540 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
542 s64 delta = (s64)(vdisktime - min_vdisktime);
544 min_vdisktime = vdisktime;
546 return min_vdisktime;
549 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
551 s64 delta = (s64)(vdisktime - min_vdisktime);
553 min_vdisktime = vdisktime;
555 return min_vdisktime;
558 static void update_min_vdisktime(struct cfq_rb_root *st)
560 struct cfq_group *cfqg;
563 cfqg = rb_entry_cfqg(st->left);
564 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
570 * get averaged number of queues of RT/BE priority.
571 * average is updated, with a formula that gives more weight to higher numbers,
572 * to quickly follows sudden increases and decrease slowly
575 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
576 struct cfq_group *cfqg, bool rt)
578 unsigned min_q, max_q;
579 unsigned mult = cfq_hist_divisor - 1;
580 unsigned round = cfq_hist_divisor / 2;
581 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
583 min_q = min(cfqg->busy_queues_avg[rt], busy);
584 max_q = max(cfqg->busy_queues_avg[rt], busy);
585 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
587 return cfqg->busy_queues_avg[rt];
590 static inline unsigned
591 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
593 struct cfq_rb_root *st = &cfqd->grp_service_tree;
595 return cfq_target_latency * cfqg->weight / st->total_weight;
598 static inline unsigned
599 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
601 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
602 if (cfqd->cfq_latency) {
604 * interested queues (we consider only the ones with the same
605 * priority class in the cfq group)
607 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
609 unsigned sync_slice = cfqd->cfq_slice[1];
610 unsigned expect_latency = sync_slice * iq;
611 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
613 if (expect_latency > group_slice) {
614 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
615 /* scale low_slice according to IO priority
616 * and sync vs async */
618 min(slice, base_low_slice * slice / sync_slice);
619 /* the adapted slice value is scaled to fit all iqs
620 * into the target latency */
621 slice = max(slice * group_slice / expect_latency,
629 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
631 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
633 cfqq->slice_start = jiffies;
634 cfqq->slice_end = jiffies + slice;
635 cfqq->allocated_slice = slice;
636 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
640 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
641 * isn't valid until the first request from the dispatch is activated
642 * and the slice time set.
644 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
646 if (cfq_cfqq_slice_new(cfqq))
648 if (time_before(jiffies, cfqq->slice_end))
655 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
656 * We choose the request that is closest to the head right now. Distance
657 * behind the head is penalized and only allowed to a certain extent.
659 static struct request *
660 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
662 sector_t s1, s2, d1 = 0, d2 = 0;
663 unsigned long back_max;
664 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
665 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
666 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
668 if (rq1 == NULL || rq1 == rq2)
673 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
675 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
677 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
679 else if ((rq2->cmd_flags & REQ_META) &&
680 !(rq1->cmd_flags & REQ_META))
683 s1 = blk_rq_pos(rq1);
684 s2 = blk_rq_pos(rq2);
687 * by definition, 1KiB is 2 sectors
689 back_max = cfqd->cfq_back_max * 2;
692 * Strict one way elevator _except_ in the case where we allow
693 * short backward seeks which are biased as twice the cost of a
694 * similar forward seek.
698 else if (s1 + back_max >= last)
699 d1 = (last - s1) * cfqd->cfq_back_penalty;
701 wrap |= CFQ_RQ1_WRAP;
705 else if (s2 + back_max >= last)
706 d2 = (last - s2) * cfqd->cfq_back_penalty;
708 wrap |= CFQ_RQ2_WRAP;
710 /* Found required data */
713 * By doing switch() on the bit mask "wrap" we avoid having to
714 * check two variables for all permutations: --> faster!
717 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
733 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
736 * Since both rqs are wrapped,
737 * start with the one that's further behind head
738 * (--> only *one* back seek required),
739 * since back seek takes more time than forward.
749 * The below is leftmost cache rbtree addon
751 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
753 /* Service tree is empty */
758 root->left = rb_first(&root->rb);
761 return rb_entry(root->left, struct cfq_queue, rb_node);
766 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
769 root->left = rb_first(&root->rb);
772 return rb_entry_cfqg(root->left);
777 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
783 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
787 rb_erase_init(n, &root->rb);
792 * would be nice to take fifo expire time into account as well
794 static struct request *
795 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
796 struct request *last)
798 struct rb_node *rbnext = rb_next(&last->rb_node);
799 struct rb_node *rbprev = rb_prev(&last->rb_node);
800 struct request *next = NULL, *prev = NULL;
802 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
805 prev = rb_entry_rq(rbprev);
808 next = rb_entry_rq(rbnext);
810 rbnext = rb_first(&cfqq->sort_list);
811 if (rbnext && rbnext != &last->rb_node)
812 next = rb_entry_rq(rbnext);
815 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
818 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
819 struct cfq_queue *cfqq)
822 * just an approximation, should be ok.
824 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
825 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
829 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
831 return cfqg->vdisktime - st->min_vdisktime;
835 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
837 struct rb_node **node = &st->rb.rb_node;
838 struct rb_node *parent = NULL;
839 struct cfq_group *__cfqg;
840 s64 key = cfqg_key(st, cfqg);
843 while (*node != NULL) {
845 __cfqg = rb_entry_cfqg(parent);
847 if (key < cfqg_key(st, __cfqg))
848 node = &parent->rb_left;
850 node = &parent->rb_right;
856 st->left = &cfqg->rb_node;
858 rb_link_node(&cfqg->rb_node, parent, node);
859 rb_insert_color(&cfqg->rb_node, &st->rb);
863 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
865 struct cfq_rb_root *st = &cfqd->grp_service_tree;
866 struct cfq_group *__cfqg;
870 if (!RB_EMPTY_NODE(&cfqg->rb_node))
874 * Currently put the group at the end. Later implement something
875 * so that groups get lesser vtime based on their weights, so that
876 * if group does not loose all if it was not continously backlogged.
878 n = rb_last(&st->rb);
880 __cfqg = rb_entry_cfqg(n);
881 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
883 cfqg->vdisktime = st->min_vdisktime;
885 __cfq_group_service_tree_add(st, cfqg);
886 st->total_weight += cfqg->weight;
890 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
892 struct cfq_rb_root *st = &cfqd->grp_service_tree;
894 BUG_ON(cfqg->nr_cfqq < 1);
897 /* If there are other cfq queues under this group, don't delete it */
901 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
902 st->total_weight -= cfqg->weight;
903 if (!RB_EMPTY_NODE(&cfqg->rb_node))
904 cfq_rb_erase(&cfqg->rb_node, st);
905 cfqg->saved_workload_slice = 0;
906 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
909 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
911 unsigned int slice_used;
914 * Queue got expired before even a single request completed or
915 * got expired immediately after first request completion.
917 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
919 * Also charge the seek time incurred to the group, otherwise
920 * if there are mutiple queues in the group, each can dispatch
921 * a single request on seeky media and cause lots of seek time
922 * and group will never know it.
924 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
927 slice_used = jiffies - cfqq->slice_start;
928 if (slice_used > cfqq->allocated_slice)
929 slice_used = cfqq->allocated_slice;
935 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
936 struct cfq_queue *cfqq)
938 struct cfq_rb_root *st = &cfqd->grp_service_tree;
939 unsigned int used_sl, charge;
940 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
941 - cfqg->service_tree_idle.count;
944 used_sl = charge = cfq_cfqq_slice_usage(cfqq);
947 charge = cfqq->slice_dispatch;
948 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
949 charge = cfqq->allocated_slice;
951 /* Can't update vdisktime while group is on service tree */
952 cfq_rb_erase(&cfqg->rb_node, st);
953 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
954 __cfq_group_service_tree_add(st, cfqg);
956 /* This group is being expired. Save the context */
957 if (time_after(cfqd->workload_expires, jiffies)) {
958 cfqg->saved_workload_slice = cfqd->workload_expires
960 cfqg->saved_workload = cfqd->serving_type;
961 cfqg->saved_serving_prio = cfqd->serving_prio;
963 cfqg->saved_workload_slice = 0;
965 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
967 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
968 " sect=%u", used_sl, cfqq->slice_dispatch, charge,
969 iops_mode(cfqd), cfqq->nr_sectors);
970 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
971 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
974 #ifdef CONFIG_CFQ_GROUP_IOSCHED
975 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
978 return container_of(blkg, struct cfq_group, blkg);
982 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
985 cfqg_of_blkg(blkg)->weight = weight;
988 static struct cfq_group *
989 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
991 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
992 struct cfq_group *cfqg = NULL;
995 struct cfq_rb_root *st;
996 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
997 unsigned int major, minor;
999 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1000 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1001 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1002 cfqg->blkg.dev = MKDEV(major, minor);
1005 if (cfqg || !create)
1008 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1012 for_each_cfqg_st(cfqg, i, j, st)
1014 RB_CLEAR_NODE(&cfqg->rb_node);
1017 * Take the initial reference that will be released on destroy
1018 * This can be thought of a joint reference by cgroup and
1019 * elevator which will be dropped by either elevator exit
1020 * or cgroup deletion path depending on who is exiting first.
1025 * Add group onto cgroup list. It might happen that bdi->dev is
1026 * not initialized yet. Initialize this new group without major
1027 * and minor info and this info will be filled in once a new thread
1028 * comes for IO. See code above.
1031 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1032 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1033 MKDEV(major, minor));
1035 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1038 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1040 /* Add group on cfqd list */
1041 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1048 * Search for the cfq group current task belongs to. If create = 1, then also
1049 * create the cfq group if it does not exist. request_queue lock must be held.
1051 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1053 struct cgroup *cgroup;
1054 struct cfq_group *cfqg = NULL;
1057 cgroup = task_cgroup(current, blkio_subsys_id);
1058 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1059 if (!cfqg && create)
1060 cfqg = &cfqd->root_group;
1065 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1071 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1073 /* Currently, all async queues are mapped to root group */
1074 if (!cfq_cfqq_sync(cfqq))
1075 cfqg = &cfqq->cfqd->root_group;
1078 /* cfqq reference on cfqg */
1082 static void cfq_put_cfqg(struct cfq_group *cfqg)
1084 struct cfq_rb_root *st;
1087 BUG_ON(cfqg->ref <= 0);
1091 for_each_cfqg_st(cfqg, i, j, st)
1092 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1096 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1098 /* Something wrong if we are trying to remove same group twice */
1099 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1101 hlist_del_init(&cfqg->cfqd_node);
1104 * Put the reference taken at the time of creation so that when all
1105 * queues are gone, group can be destroyed.
1110 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1112 struct hlist_node *pos, *n;
1113 struct cfq_group *cfqg;
1115 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1117 * If cgroup removal path got to blk_group first and removed
1118 * it from cgroup list, then it will take care of destroying
1121 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1122 cfq_destroy_cfqg(cfqd, cfqg);
1127 * Blk cgroup controller notification saying that blkio_group object is being
1128 * delinked as associated cgroup object is going away. That also means that
1129 * no new IO will come in this group. So get rid of this group as soon as
1130 * any pending IO in the group is finished.
1132 * This function is called under rcu_read_lock(). key is the rcu protected
1133 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1136 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1137 * it should not be NULL as even if elevator was exiting, cgroup deltion
1138 * path got to it first.
1140 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1142 unsigned long flags;
1143 struct cfq_data *cfqd = key;
1145 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1146 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1147 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1150 #else /* GROUP_IOSCHED */
1151 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1153 return &cfqd->root_group;
1156 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1162 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1166 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1167 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1169 #endif /* GROUP_IOSCHED */
1172 * The cfqd->service_trees holds all pending cfq_queue's that have
1173 * requests waiting to be processed. It is sorted in the order that
1174 * we will service the queues.
1176 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1179 struct rb_node **p, *parent;
1180 struct cfq_queue *__cfqq;
1181 unsigned long rb_key;
1182 struct cfq_rb_root *service_tree;
1185 int group_changed = 0;
1187 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1189 if (cfq_class_idle(cfqq)) {
1190 rb_key = CFQ_IDLE_DELAY;
1191 parent = rb_last(&service_tree->rb);
1192 if (parent && parent != &cfqq->rb_node) {
1193 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1194 rb_key += __cfqq->rb_key;
1197 } else if (!add_front) {
1199 * Get our rb key offset. Subtract any residual slice
1200 * value carried from last service. A negative resid
1201 * count indicates slice overrun, and this should position
1202 * the next service time further away in the tree.
1204 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1205 rb_key -= cfqq->slice_resid;
1206 cfqq->slice_resid = 0;
1209 __cfqq = cfq_rb_first(service_tree);
1210 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1213 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1216 * same position, nothing more to do
1218 if (rb_key == cfqq->rb_key &&
1219 cfqq->service_tree == service_tree)
1222 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1223 cfqq->service_tree = NULL;
1228 cfqq->service_tree = service_tree;
1229 p = &service_tree->rb.rb_node;
1234 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1237 * sort by key, that represents service time.
1239 if (time_before(rb_key, __cfqq->rb_key))
1242 n = &(*p)->rb_right;
1250 service_tree->left = &cfqq->rb_node;
1252 cfqq->rb_key = rb_key;
1253 rb_link_node(&cfqq->rb_node, parent, p);
1254 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1255 service_tree->count++;
1256 if ((add_front || !new_cfqq) && !group_changed)
1258 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1261 static struct cfq_queue *
1262 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1263 sector_t sector, struct rb_node **ret_parent,
1264 struct rb_node ***rb_link)
1266 struct rb_node **p, *parent;
1267 struct cfq_queue *cfqq = NULL;
1275 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1278 * Sort strictly based on sector. Smallest to the left,
1279 * largest to the right.
1281 if (sector > blk_rq_pos(cfqq->next_rq))
1282 n = &(*p)->rb_right;
1283 else if (sector < blk_rq_pos(cfqq->next_rq))
1291 *ret_parent = parent;
1297 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1299 struct rb_node **p, *parent;
1300 struct cfq_queue *__cfqq;
1303 rb_erase(&cfqq->p_node, cfqq->p_root);
1304 cfqq->p_root = NULL;
1307 if (cfq_class_idle(cfqq))
1312 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1313 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1314 blk_rq_pos(cfqq->next_rq), &parent, &p);
1316 rb_link_node(&cfqq->p_node, parent, p);
1317 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1319 cfqq->p_root = NULL;
1323 * Update cfqq's position in the service tree.
1325 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1328 * Resorting requires the cfqq to be on the RR list already.
1330 if (cfq_cfqq_on_rr(cfqq)) {
1331 cfq_service_tree_add(cfqd, cfqq, 0);
1332 cfq_prio_tree_add(cfqd, cfqq);
1337 * add to busy list of queues for service, trying to be fair in ordering
1338 * the pending list according to last request service
1340 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1342 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1343 BUG_ON(cfq_cfqq_on_rr(cfqq));
1344 cfq_mark_cfqq_on_rr(cfqq);
1345 cfqd->busy_queues++;
1346 if (cfq_cfqq_sync(cfqq))
1347 cfqd->busy_sync_queues++;
1349 cfq_resort_rr_list(cfqd, cfqq);
1353 * Called when the cfqq no longer has requests pending, remove it from
1356 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1358 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1359 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1360 cfq_clear_cfqq_on_rr(cfqq);
1362 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1363 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1364 cfqq->service_tree = NULL;
1367 rb_erase(&cfqq->p_node, cfqq->p_root);
1368 cfqq->p_root = NULL;
1371 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1372 BUG_ON(!cfqd->busy_queues);
1373 cfqd->busy_queues--;
1374 if (cfq_cfqq_sync(cfqq))
1375 cfqd->busy_sync_queues--;
1379 * rb tree support functions
1381 static void cfq_del_rq_rb(struct request *rq)
1383 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1384 const int sync = rq_is_sync(rq);
1386 BUG_ON(!cfqq->queued[sync]);
1387 cfqq->queued[sync]--;
1389 elv_rb_del(&cfqq->sort_list, rq);
1391 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1393 * Queue will be deleted from service tree when we actually
1394 * expire it later. Right now just remove it from prio tree
1398 rb_erase(&cfqq->p_node, cfqq->p_root);
1399 cfqq->p_root = NULL;
1404 static void cfq_add_rq_rb(struct request *rq)
1406 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1407 struct cfq_data *cfqd = cfqq->cfqd;
1408 struct request *__alias, *prev;
1410 cfqq->queued[rq_is_sync(rq)]++;
1413 * looks a little odd, but the first insert might return an alias.
1414 * if that happens, put the alias on the dispatch list
1416 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1417 cfq_dispatch_insert(cfqd->queue, __alias);
1419 if (!cfq_cfqq_on_rr(cfqq))
1420 cfq_add_cfqq_rr(cfqd, cfqq);
1423 * check if this request is a better next-serve candidate
1425 prev = cfqq->next_rq;
1426 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1429 * adjust priority tree position, if ->next_rq changes
1431 if (prev != cfqq->next_rq)
1432 cfq_prio_tree_add(cfqd, cfqq);
1434 BUG_ON(!cfqq->next_rq);
1437 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1439 elv_rb_del(&cfqq->sort_list, rq);
1440 cfqq->queued[rq_is_sync(rq)]--;
1441 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1442 rq_data_dir(rq), rq_is_sync(rq));
1444 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1445 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1449 static struct request *
1450 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1452 struct task_struct *tsk = current;
1453 struct cfq_io_context *cic;
1454 struct cfq_queue *cfqq;
1456 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1460 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1462 sector_t sector = bio->bi_sector + bio_sectors(bio);
1464 return elv_rb_find(&cfqq->sort_list, sector);
1470 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1472 struct cfq_data *cfqd = q->elevator->elevator_data;
1474 cfqd->rq_in_driver++;
1475 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1476 cfqd->rq_in_driver);
1478 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1481 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1483 struct cfq_data *cfqd = q->elevator->elevator_data;
1485 WARN_ON(!cfqd->rq_in_driver);
1486 cfqd->rq_in_driver--;
1487 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1488 cfqd->rq_in_driver);
1491 static void cfq_remove_request(struct request *rq)
1493 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1495 if (cfqq->next_rq == rq)
1496 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1498 list_del_init(&rq->queuelist);
1501 cfqq->cfqd->rq_queued--;
1502 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1503 rq_data_dir(rq), rq_is_sync(rq));
1504 if (rq->cmd_flags & REQ_META) {
1505 WARN_ON(!cfqq->meta_pending);
1506 cfqq->meta_pending--;
1510 static int cfq_merge(struct request_queue *q, struct request **req,
1513 struct cfq_data *cfqd = q->elevator->elevator_data;
1514 struct request *__rq;
1516 __rq = cfq_find_rq_fmerge(cfqd, bio);
1517 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1519 return ELEVATOR_FRONT_MERGE;
1522 return ELEVATOR_NO_MERGE;
1525 static void cfq_merged_request(struct request_queue *q, struct request *req,
1528 if (type == ELEVATOR_FRONT_MERGE) {
1529 struct cfq_queue *cfqq = RQ_CFQQ(req);
1531 cfq_reposition_rq_rb(cfqq, req);
1535 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1538 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1539 bio_data_dir(bio), cfq_bio_sync(bio));
1543 cfq_merged_requests(struct request_queue *q, struct request *rq,
1544 struct request *next)
1546 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1548 * reposition in fifo if next is older than rq
1550 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1551 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1552 list_move(&rq->queuelist, &next->queuelist);
1553 rq_set_fifo_time(rq, rq_fifo_time(next));
1556 if (cfqq->next_rq == next)
1558 cfq_remove_request(next);
1559 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1560 rq_data_dir(next), rq_is_sync(next));
1563 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1566 struct cfq_data *cfqd = q->elevator->elevator_data;
1567 struct cfq_io_context *cic;
1568 struct cfq_queue *cfqq;
1571 * Disallow merge of a sync bio into an async request.
1573 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1577 * Lookup the cfqq that this bio will be queued with. Allow
1578 * merge only if rq is queued there.
1580 cic = cfq_cic_lookup(cfqd, current->io_context);
1584 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1585 return cfqq == RQ_CFQQ(rq);
1588 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1590 del_timer(&cfqd->idle_slice_timer);
1591 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1594 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1595 struct cfq_queue *cfqq)
1598 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1599 cfqd->serving_prio, cfqd->serving_type);
1600 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1601 cfqq->slice_start = 0;
1602 cfqq->dispatch_start = jiffies;
1603 cfqq->allocated_slice = 0;
1604 cfqq->slice_end = 0;
1605 cfqq->slice_dispatch = 0;
1606 cfqq->nr_sectors = 0;
1608 cfq_clear_cfqq_wait_request(cfqq);
1609 cfq_clear_cfqq_must_dispatch(cfqq);
1610 cfq_clear_cfqq_must_alloc_slice(cfqq);
1611 cfq_clear_cfqq_fifo_expire(cfqq);
1612 cfq_mark_cfqq_slice_new(cfqq);
1614 cfq_del_timer(cfqd, cfqq);
1617 cfqd->active_queue = cfqq;
1621 * current cfqq expired its slice (or was too idle), select new one
1624 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1627 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1629 if (cfq_cfqq_wait_request(cfqq))
1630 cfq_del_timer(cfqd, cfqq);
1632 cfq_clear_cfqq_wait_request(cfqq);
1633 cfq_clear_cfqq_wait_busy(cfqq);
1636 * If this cfqq is shared between multiple processes, check to
1637 * make sure that those processes are still issuing I/Os within
1638 * the mean seek distance. If not, it may be time to break the
1639 * queues apart again.
1641 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1642 cfq_mark_cfqq_split_coop(cfqq);
1645 * store what was left of this slice, if the queue idled/timed out
1648 if (cfq_cfqq_slice_new(cfqq))
1649 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1651 cfqq->slice_resid = cfqq->slice_end - jiffies;
1652 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1655 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1657 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1658 cfq_del_cfqq_rr(cfqd, cfqq);
1660 cfq_resort_rr_list(cfqd, cfqq);
1662 if (cfqq == cfqd->active_queue)
1663 cfqd->active_queue = NULL;
1665 if (cfqd->active_cic) {
1666 put_io_context(cfqd->active_cic->ioc);
1667 cfqd->active_cic = NULL;
1671 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1673 struct cfq_queue *cfqq = cfqd->active_queue;
1676 __cfq_slice_expired(cfqd, cfqq, timed_out);
1680 * Get next queue for service. Unless we have a queue preemption,
1681 * we'll simply select the first cfqq in the service tree.
1683 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1685 struct cfq_rb_root *service_tree =
1686 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1687 cfqd->serving_type);
1689 if (!cfqd->rq_queued)
1692 /* There is nothing to dispatch */
1695 if (RB_EMPTY_ROOT(&service_tree->rb))
1697 return cfq_rb_first(service_tree);
1700 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1702 struct cfq_group *cfqg;
1703 struct cfq_queue *cfqq;
1705 struct cfq_rb_root *st;
1707 if (!cfqd->rq_queued)
1710 cfqg = cfq_get_next_cfqg(cfqd);
1714 for_each_cfqg_st(cfqg, i, j, st)
1715 if ((cfqq = cfq_rb_first(st)) != NULL)
1721 * Get and set a new active queue for service.
1723 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1724 struct cfq_queue *cfqq)
1727 cfqq = cfq_get_next_queue(cfqd);
1729 __cfq_set_active_queue(cfqd, cfqq);
1733 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1736 if (blk_rq_pos(rq) >= cfqd->last_position)
1737 return blk_rq_pos(rq) - cfqd->last_position;
1739 return cfqd->last_position - blk_rq_pos(rq);
1742 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1745 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1748 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1749 struct cfq_queue *cur_cfqq)
1751 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1752 struct rb_node *parent, *node;
1753 struct cfq_queue *__cfqq;
1754 sector_t sector = cfqd->last_position;
1756 if (RB_EMPTY_ROOT(root))
1760 * First, if we find a request starting at the end of the last
1761 * request, choose it.
1763 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1768 * If the exact sector wasn't found, the parent of the NULL leaf
1769 * will contain the closest sector.
1771 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1772 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1775 if (blk_rq_pos(__cfqq->next_rq) < sector)
1776 node = rb_next(&__cfqq->p_node);
1778 node = rb_prev(&__cfqq->p_node);
1782 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1783 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1791 * cur_cfqq - passed in so that we don't decide that the current queue is
1792 * closely cooperating with itself.
1794 * So, basically we're assuming that that cur_cfqq has dispatched at least
1795 * one request, and that cfqd->last_position reflects a position on the disk
1796 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1799 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1800 struct cfq_queue *cur_cfqq)
1802 struct cfq_queue *cfqq;
1804 if (cfq_class_idle(cur_cfqq))
1806 if (!cfq_cfqq_sync(cur_cfqq))
1808 if (CFQQ_SEEKY(cur_cfqq))
1812 * Don't search priority tree if it's the only queue in the group.
1814 if (cur_cfqq->cfqg->nr_cfqq == 1)
1818 * We should notice if some of the queues are cooperating, eg
1819 * working closely on the same area of the disk. In that case,
1820 * we can group them together and don't waste time idling.
1822 cfqq = cfqq_close(cfqd, cur_cfqq);
1826 /* If new queue belongs to different cfq_group, don't choose it */
1827 if (cur_cfqq->cfqg != cfqq->cfqg)
1831 * It only makes sense to merge sync queues.
1833 if (!cfq_cfqq_sync(cfqq))
1835 if (CFQQ_SEEKY(cfqq))
1839 * Do not merge queues of different priority classes
1841 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1848 * Determine whether we should enforce idle window for this queue.
1851 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1853 enum wl_prio_t prio = cfqq_prio(cfqq);
1854 struct cfq_rb_root *service_tree = cfqq->service_tree;
1856 BUG_ON(!service_tree);
1857 BUG_ON(!service_tree->count);
1859 if (!cfqd->cfq_slice_idle)
1862 /* We never do for idle class queues. */
1863 if (prio == IDLE_WORKLOAD)
1866 /* We do for queues that were marked with idle window flag. */
1867 if (cfq_cfqq_idle_window(cfqq) &&
1868 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1872 * Otherwise, we do only if they are the last ones
1873 * in their service tree.
1875 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1877 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1878 service_tree->count);
1882 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1884 struct cfq_queue *cfqq = cfqd->active_queue;
1885 struct cfq_io_context *cic;
1886 unsigned long sl, group_idle = 0;
1889 * SSD device without seek penalty, disable idling. But only do so
1890 * for devices that support queuing, otherwise we still have a problem
1891 * with sync vs async workloads.
1893 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1896 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1897 WARN_ON(cfq_cfqq_slice_new(cfqq));
1900 * idle is disabled, either manually or by past process history
1902 if (!cfq_should_idle(cfqd, cfqq)) {
1903 /* no queue idling. Check for group idling */
1904 if (cfqd->cfq_group_idle)
1905 group_idle = cfqd->cfq_group_idle;
1911 * still active requests from this queue, don't idle
1913 if (cfqq->dispatched)
1917 * task has exited, don't wait
1919 cic = cfqd->active_cic;
1920 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1924 * If our average think time is larger than the remaining time
1925 * slice, then don't idle. This avoids overrunning the allotted
1928 if (sample_valid(cic->ttime_samples) &&
1929 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1930 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1935 /* There are other queues in the group, don't do group idle */
1936 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
1939 cfq_mark_cfqq_wait_request(cfqq);
1942 sl = cfqd->cfq_group_idle;
1944 sl = cfqd->cfq_slice_idle;
1946 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1947 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1948 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
1949 group_idle ? 1 : 0);
1953 * Move request from internal lists to the request queue dispatch list.
1955 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1957 struct cfq_data *cfqd = q->elevator->elevator_data;
1958 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1960 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1962 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1963 cfq_remove_request(rq);
1965 (RQ_CFQG(rq))->dispatched++;
1966 elv_dispatch_sort(q, rq);
1968 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1969 cfqq->nr_sectors += blk_rq_sectors(rq);
1970 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1971 rq_data_dir(rq), rq_is_sync(rq));
1975 * return expired entry, or NULL to just start from scratch in rbtree
1977 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1979 struct request *rq = NULL;
1981 if (cfq_cfqq_fifo_expire(cfqq))
1984 cfq_mark_cfqq_fifo_expire(cfqq);
1986 if (list_empty(&cfqq->fifo))
1989 rq = rq_entry_fifo(cfqq->fifo.next);
1990 if (time_before(jiffies, rq_fifo_time(rq)))
1993 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1998 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2000 const int base_rq = cfqd->cfq_slice_async_rq;
2002 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2004 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
2008 * Must be called with the queue_lock held.
2010 static int cfqq_process_refs(struct cfq_queue *cfqq)
2012 int process_refs, io_refs;
2014 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2015 process_refs = cfqq->ref - io_refs;
2016 BUG_ON(process_refs < 0);
2017 return process_refs;
2020 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2022 int process_refs, new_process_refs;
2023 struct cfq_queue *__cfqq;
2026 * If there are no process references on the new_cfqq, then it is
2027 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2028 * chain may have dropped their last reference (not just their
2029 * last process reference).
2031 if (!cfqq_process_refs(new_cfqq))
2034 /* Avoid a circular list and skip interim queue merges */
2035 while ((__cfqq = new_cfqq->new_cfqq)) {
2041 process_refs = cfqq_process_refs(cfqq);
2042 new_process_refs = cfqq_process_refs(new_cfqq);
2044 * If the process for the cfqq has gone away, there is no
2045 * sense in merging the queues.
2047 if (process_refs == 0 || new_process_refs == 0)
2051 * Merge in the direction of the lesser amount of work.
2053 if (new_process_refs >= process_refs) {
2054 cfqq->new_cfqq = new_cfqq;
2055 new_cfqq->ref += process_refs;
2057 new_cfqq->new_cfqq = cfqq;
2058 cfqq->ref += new_process_refs;
2062 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2063 struct cfq_group *cfqg, enum wl_prio_t prio)
2065 struct cfq_queue *queue;
2067 bool key_valid = false;
2068 unsigned long lowest_key = 0;
2069 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2071 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2072 /* select the one with lowest rb_key */
2073 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2075 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2076 lowest_key = queue->rb_key;
2085 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2089 struct cfq_rb_root *st;
2090 unsigned group_slice;
2091 enum wl_prio_t original_prio = cfqd->serving_prio;
2093 /* Choose next priority. RT > BE > IDLE */
2094 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2095 cfqd->serving_prio = RT_WORKLOAD;
2096 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2097 cfqd->serving_prio = BE_WORKLOAD;
2099 cfqd->serving_prio = IDLE_WORKLOAD;
2100 cfqd->workload_expires = jiffies + 1;
2104 if (original_prio != cfqd->serving_prio)
2108 * For RT and BE, we have to choose also the type
2109 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2112 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2116 * check workload expiration, and that we still have other queues ready
2118 if (count && !time_after(jiffies, cfqd->workload_expires))
2122 /* otherwise select new workload type */
2123 cfqd->serving_type =
2124 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2125 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2129 * the workload slice is computed as a fraction of target latency
2130 * proportional to the number of queues in that workload, over
2131 * all the queues in the same priority class
2133 group_slice = cfq_group_slice(cfqd, cfqg);
2135 slice = group_slice * count /
2136 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2137 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2139 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2143 * Async queues are currently system wide. Just taking
2144 * proportion of queues with-in same group will lead to higher
2145 * async ratio system wide as generally root group is going
2146 * to have higher weight. A more accurate thing would be to
2147 * calculate system wide asnc/sync ratio.
2149 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2150 tmp = tmp/cfqd->busy_queues;
2151 slice = min_t(unsigned, slice, tmp);
2153 /* async workload slice is scaled down according to
2154 * the sync/async slice ratio. */
2155 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2157 /* sync workload slice is at least 2 * cfq_slice_idle */
2158 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2160 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2161 cfq_log(cfqd, "workload slice:%d", slice);
2162 cfqd->workload_expires = jiffies + slice;
2165 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2167 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2168 struct cfq_group *cfqg;
2170 if (RB_EMPTY_ROOT(&st->rb))
2172 cfqg = cfq_rb_first_group(st);
2173 update_min_vdisktime(st);
2177 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2179 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2181 cfqd->serving_group = cfqg;
2183 /* Restore the workload type data */
2184 if (cfqg->saved_workload_slice) {
2185 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2186 cfqd->serving_type = cfqg->saved_workload;
2187 cfqd->serving_prio = cfqg->saved_serving_prio;
2189 cfqd->workload_expires = jiffies - 1;
2191 choose_service_tree(cfqd, cfqg);
2195 * Select a queue for service. If we have a current active queue,
2196 * check whether to continue servicing it, or retrieve and set a new one.
2198 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2200 struct cfq_queue *cfqq, *new_cfqq = NULL;
2202 cfqq = cfqd->active_queue;
2206 if (!cfqd->rq_queued)
2210 * We were waiting for group to get backlogged. Expire the queue
2212 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2216 * The active queue has run out of time, expire it and select new.
2218 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2220 * If slice had not expired at the completion of last request
2221 * we might not have turned on wait_busy flag. Don't expire
2222 * the queue yet. Allow the group to get backlogged.
2224 * The very fact that we have used the slice, that means we
2225 * have been idling all along on this queue and it should be
2226 * ok to wait for this request to complete.
2228 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2229 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2233 goto check_group_idle;
2237 * The active queue has requests and isn't expired, allow it to
2240 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2244 * If another queue has a request waiting within our mean seek
2245 * distance, let it run. The expire code will check for close
2246 * cooperators and put the close queue at the front of the service
2247 * tree. If possible, merge the expiring queue with the new cfqq.
2249 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2251 if (!cfqq->new_cfqq)
2252 cfq_setup_merge(cfqq, new_cfqq);
2257 * No requests pending. If the active queue still has requests in
2258 * flight or is idling for a new request, allow either of these
2259 * conditions to happen (or time out) before selecting a new queue.
2261 if (timer_pending(&cfqd->idle_slice_timer)) {
2267 * This is a deep seek queue, but the device is much faster than
2268 * the queue can deliver, don't idle
2270 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2271 (cfq_cfqq_slice_new(cfqq) ||
2272 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2273 cfq_clear_cfqq_deep(cfqq);
2274 cfq_clear_cfqq_idle_window(cfqq);
2277 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2283 * If group idle is enabled and there are requests dispatched from
2284 * this group, wait for requests to complete.
2287 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2288 && cfqq->cfqg->dispatched) {
2294 cfq_slice_expired(cfqd, 0);
2297 * Current queue expired. Check if we have to switch to a new
2301 cfq_choose_cfqg(cfqd);
2303 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2308 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2312 while (cfqq->next_rq) {
2313 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2317 BUG_ON(!list_empty(&cfqq->fifo));
2319 /* By default cfqq is not expired if it is empty. Do it explicitly */
2320 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2325 * Drain our current requests. Used for barriers and when switching
2326 * io schedulers on-the-fly.
2328 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2330 struct cfq_queue *cfqq;
2333 /* Expire the timeslice of the current active queue first */
2334 cfq_slice_expired(cfqd, 0);
2335 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2336 __cfq_set_active_queue(cfqd, cfqq);
2337 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2340 BUG_ON(cfqd->busy_queues);
2342 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2346 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2347 struct cfq_queue *cfqq)
2349 /* the queue hasn't finished any request, can't estimate */
2350 if (cfq_cfqq_slice_new(cfqq))
2352 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2359 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2361 unsigned int max_dispatch;
2364 * Drain async requests before we start sync IO
2366 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2370 * If this is an async queue and we have sync IO in flight, let it wait
2372 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2375 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2376 if (cfq_class_idle(cfqq))
2380 * Does this cfqq already have too much IO in flight?
2382 if (cfqq->dispatched >= max_dispatch) {
2383 bool promote_sync = false;
2385 * idle queue must always only have a single IO in flight
2387 if (cfq_class_idle(cfqq))
2391 * If there is only one sync queue, and its think time is
2392 * small, we can ignore async queue here and give the sync
2393 * queue no dispatch limit. The reason is a sync queue can
2394 * preempt async queue, limiting the sync queue doesn't make
2395 * sense. This is useful for aiostress test.
2397 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) {
2398 struct cfq_io_context *cic = RQ_CIC(cfqq->next_rq);
2400 if (sample_valid(cic->ttime_samples) &&
2401 cic->ttime_mean < cfqd->cfq_slice_idle)
2402 promote_sync = true;
2406 * We have other queues, don't allow more IO from this one
2408 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2413 * Sole queue user, no limit
2415 if (cfqd->busy_queues == 1 || promote_sync)
2419 * Normally we start throttling cfqq when cfq_quantum/2
2420 * requests have been dispatched. But we can drive
2421 * deeper queue depths at the beginning of slice
2422 * subjected to upper limit of cfq_quantum.
2424 max_dispatch = cfqd->cfq_quantum;
2428 * Async queues must wait a bit before being allowed dispatch.
2429 * We also ramp up the dispatch depth gradually for async IO,
2430 * based on the last sync IO we serviced
2432 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2433 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2436 depth = last_sync / cfqd->cfq_slice[1];
2437 if (!depth && !cfqq->dispatched)
2439 if (depth < max_dispatch)
2440 max_dispatch = depth;
2444 * If we're below the current max, allow a dispatch
2446 return cfqq->dispatched < max_dispatch;
2450 * Dispatch a request from cfqq, moving them to the request queue
2453 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2457 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2459 if (!cfq_may_dispatch(cfqd, cfqq))
2463 * follow expired path, else get first next available
2465 rq = cfq_check_fifo(cfqq);
2470 * insert request into driver dispatch list
2472 cfq_dispatch_insert(cfqd->queue, rq);
2474 if (!cfqd->active_cic) {
2475 struct cfq_io_context *cic = RQ_CIC(rq);
2477 atomic_long_inc(&cic->ioc->refcount);
2478 cfqd->active_cic = cic;
2485 * Find the cfqq that we need to service and move a request from that to the
2488 static int cfq_dispatch_requests(struct request_queue *q, int force)
2490 struct cfq_data *cfqd = q->elevator->elevator_data;
2491 struct cfq_queue *cfqq;
2493 if (!cfqd->busy_queues)
2496 if (unlikely(force))
2497 return cfq_forced_dispatch(cfqd);
2499 cfqq = cfq_select_queue(cfqd);
2504 * Dispatch a request from this cfqq, if it is allowed
2506 if (!cfq_dispatch_request(cfqd, cfqq))
2509 cfqq->slice_dispatch++;
2510 cfq_clear_cfqq_must_dispatch(cfqq);
2513 * expire an async queue immediately if it has used up its slice. idle
2514 * queue always expire after 1 dispatch round.
2516 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2517 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2518 cfq_class_idle(cfqq))) {
2519 cfqq->slice_end = jiffies + 1;
2520 cfq_slice_expired(cfqd, 0);
2523 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2528 * task holds one reference to the queue, dropped when task exits. each rq
2529 * in-flight on this queue also holds a reference, dropped when rq is freed.
2531 * Each cfq queue took a reference on the parent group. Drop it now.
2532 * queue lock must be held here.
2534 static void cfq_put_queue(struct cfq_queue *cfqq)
2536 struct cfq_data *cfqd = cfqq->cfqd;
2537 struct cfq_group *cfqg;
2539 BUG_ON(cfqq->ref <= 0);
2545 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2546 BUG_ON(rb_first(&cfqq->sort_list));
2547 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2550 if (unlikely(cfqd->active_queue == cfqq)) {
2551 __cfq_slice_expired(cfqd, cfqq, 0);
2552 cfq_schedule_dispatch(cfqd);
2555 BUG_ON(cfq_cfqq_on_rr(cfqq));
2556 kmem_cache_free(cfq_pool, cfqq);
2561 * Must always be called with the rcu_read_lock() held
2564 __call_for_each_cic(struct io_context *ioc,
2565 void (*func)(struct io_context *, struct cfq_io_context *))
2567 struct cfq_io_context *cic;
2568 struct hlist_node *n;
2570 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2575 * Call func for each cic attached to this ioc.
2578 call_for_each_cic(struct io_context *ioc,
2579 void (*func)(struct io_context *, struct cfq_io_context *))
2582 __call_for_each_cic(ioc, func);
2586 static void cfq_cic_free_rcu(struct rcu_head *head)
2588 struct cfq_io_context *cic;
2590 cic = container_of(head, struct cfq_io_context, rcu_head);
2592 kmem_cache_free(cfq_ioc_pool, cic);
2593 elv_ioc_count_dec(cfq_ioc_count);
2597 * CFQ scheduler is exiting, grab exit lock and check
2598 * the pending io context count. If it hits zero,
2599 * complete ioc_gone and set it back to NULL
2601 spin_lock(&ioc_gone_lock);
2602 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2606 spin_unlock(&ioc_gone_lock);
2610 static void cfq_cic_free(struct cfq_io_context *cic)
2612 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2615 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2617 unsigned long flags;
2618 unsigned long dead_key = (unsigned long) cic->key;
2620 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2622 spin_lock_irqsave(&ioc->lock, flags);
2623 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2624 hlist_del_rcu(&cic->cic_list);
2625 spin_unlock_irqrestore(&ioc->lock, flags);
2631 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2632 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2633 * and ->trim() which is called with the task lock held
2635 static void cfq_free_io_context(struct io_context *ioc)
2638 * ioc->refcount is zero here, or we are called from elv_unregister(),
2639 * so no more cic's are allowed to be linked into this ioc. So it
2640 * should be ok to iterate over the known list, we will see all cic's
2641 * since no new ones are added.
2643 __call_for_each_cic(ioc, cic_free_func);
2646 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2648 struct cfq_queue *__cfqq, *next;
2651 * If this queue was scheduled to merge with another queue, be
2652 * sure to drop the reference taken on that queue (and others in
2653 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2655 __cfqq = cfqq->new_cfqq;
2657 if (__cfqq == cfqq) {
2658 WARN(1, "cfqq->new_cfqq loop detected\n");
2661 next = __cfqq->new_cfqq;
2662 cfq_put_queue(__cfqq);
2667 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2669 if (unlikely(cfqq == cfqd->active_queue)) {
2670 __cfq_slice_expired(cfqd, cfqq, 0);
2671 cfq_schedule_dispatch(cfqd);
2674 cfq_put_cooperator(cfqq);
2676 cfq_put_queue(cfqq);
2679 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2680 struct cfq_io_context *cic)
2682 struct io_context *ioc = cic->ioc;
2684 list_del_init(&cic->queue_list);
2687 * Make sure dead mark is seen for dead queues
2690 cic->key = cfqd_dead_key(cfqd);
2692 if (ioc->ioc_data == cic)
2693 rcu_assign_pointer(ioc->ioc_data, NULL);
2695 if (cic->cfqq[BLK_RW_ASYNC]) {
2696 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2697 cic->cfqq[BLK_RW_ASYNC] = NULL;
2700 if (cic->cfqq[BLK_RW_SYNC]) {
2701 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2702 cic->cfqq[BLK_RW_SYNC] = NULL;
2706 static void cfq_exit_single_io_context(struct io_context *ioc,
2707 struct cfq_io_context *cic)
2709 struct cfq_data *cfqd = cic_to_cfqd(cic);
2712 struct request_queue *q = cfqd->queue;
2713 unsigned long flags;
2715 spin_lock_irqsave(q->queue_lock, flags);
2718 * Ensure we get a fresh copy of the ->key to prevent
2719 * race between exiting task and queue
2721 smp_read_barrier_depends();
2722 if (cic->key == cfqd)
2723 __cfq_exit_single_io_context(cfqd, cic);
2725 spin_unlock_irqrestore(q->queue_lock, flags);
2730 * The process that ioc belongs to has exited, we need to clean up
2731 * and put the internal structures we have that belongs to that process.
2733 static void cfq_exit_io_context(struct io_context *ioc)
2735 call_for_each_cic(ioc, cfq_exit_single_io_context);
2738 static struct cfq_io_context *
2739 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2741 struct cfq_io_context *cic;
2743 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2746 cic->last_end_request = jiffies;
2747 INIT_LIST_HEAD(&cic->queue_list);
2748 INIT_HLIST_NODE(&cic->cic_list);
2749 cic->dtor = cfq_free_io_context;
2750 cic->exit = cfq_exit_io_context;
2751 elv_ioc_count_inc(cfq_ioc_count);
2757 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2759 struct task_struct *tsk = current;
2762 if (!cfq_cfqq_prio_changed(cfqq))
2765 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2766 switch (ioprio_class) {
2768 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2769 case IOPRIO_CLASS_NONE:
2771 * no prio set, inherit CPU scheduling settings
2773 cfqq->ioprio = task_nice_ioprio(tsk);
2774 cfqq->ioprio_class = task_nice_ioclass(tsk);
2776 case IOPRIO_CLASS_RT:
2777 cfqq->ioprio = task_ioprio(ioc);
2778 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2780 case IOPRIO_CLASS_BE:
2781 cfqq->ioprio = task_ioprio(ioc);
2782 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2784 case IOPRIO_CLASS_IDLE:
2785 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2787 cfq_clear_cfqq_idle_window(cfqq);
2792 * keep track of original prio settings in case we have to temporarily
2793 * elevate the priority of this queue
2795 cfqq->org_ioprio = cfqq->ioprio;
2796 cfqq->org_ioprio_class = cfqq->ioprio_class;
2797 cfq_clear_cfqq_prio_changed(cfqq);
2800 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2802 struct cfq_data *cfqd = cic_to_cfqd(cic);
2803 struct cfq_queue *cfqq;
2804 unsigned long flags;
2806 if (unlikely(!cfqd))
2809 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2811 cfqq = cic->cfqq[BLK_RW_ASYNC];
2813 struct cfq_queue *new_cfqq;
2814 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2817 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2818 cfq_put_queue(cfqq);
2822 cfqq = cic->cfqq[BLK_RW_SYNC];
2824 cfq_mark_cfqq_prio_changed(cfqq);
2826 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2829 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2831 call_for_each_cic(ioc, changed_ioprio);
2832 ioc->ioprio_changed = 0;
2835 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2836 pid_t pid, bool is_sync)
2838 RB_CLEAR_NODE(&cfqq->rb_node);
2839 RB_CLEAR_NODE(&cfqq->p_node);
2840 INIT_LIST_HEAD(&cfqq->fifo);
2845 cfq_mark_cfqq_prio_changed(cfqq);
2848 if (!cfq_class_idle(cfqq))
2849 cfq_mark_cfqq_idle_window(cfqq);
2850 cfq_mark_cfqq_sync(cfqq);
2855 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2856 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2858 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2859 struct cfq_data *cfqd = cic_to_cfqd(cic);
2860 unsigned long flags;
2861 struct request_queue *q;
2863 if (unlikely(!cfqd))
2868 spin_lock_irqsave(q->queue_lock, flags);
2872 * Drop reference to sync queue. A new sync queue will be
2873 * assigned in new group upon arrival of a fresh request.
2875 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2876 cic_set_cfqq(cic, NULL, 1);
2877 cfq_put_queue(sync_cfqq);
2880 spin_unlock_irqrestore(q->queue_lock, flags);
2883 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2885 call_for_each_cic(ioc, changed_cgroup);
2886 ioc->cgroup_changed = 0;
2888 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2890 static struct cfq_queue *
2891 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2892 struct io_context *ioc, gfp_t gfp_mask)
2894 struct cfq_queue *cfqq, *new_cfqq = NULL;
2895 struct cfq_io_context *cic;
2896 struct cfq_group *cfqg;
2899 cfqg = cfq_get_cfqg(cfqd, 1);
2900 cic = cfq_cic_lookup(cfqd, ioc);
2901 /* cic always exists here */
2902 cfqq = cic_to_cfqq(cic, is_sync);
2905 * Always try a new alloc if we fell back to the OOM cfqq
2906 * originally, since it should just be a temporary situation.
2908 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2913 } else if (gfp_mask & __GFP_WAIT) {
2914 spin_unlock_irq(cfqd->queue->queue_lock);
2915 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2916 gfp_mask | __GFP_ZERO,
2918 spin_lock_irq(cfqd->queue->queue_lock);
2922 cfqq = kmem_cache_alloc_node(cfq_pool,
2923 gfp_mask | __GFP_ZERO,
2928 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2929 cfq_init_prio_data(cfqq, ioc);
2930 cfq_link_cfqq_cfqg(cfqq, cfqg);
2931 cfq_log_cfqq(cfqd, cfqq, "alloced");
2933 cfqq = &cfqd->oom_cfqq;
2937 kmem_cache_free(cfq_pool, new_cfqq);
2942 static struct cfq_queue **
2943 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2945 switch (ioprio_class) {
2946 case IOPRIO_CLASS_RT:
2947 return &cfqd->async_cfqq[0][ioprio];
2948 case IOPRIO_CLASS_BE:
2949 return &cfqd->async_cfqq[1][ioprio];
2950 case IOPRIO_CLASS_IDLE:
2951 return &cfqd->async_idle_cfqq;
2957 static struct cfq_queue *
2958 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2961 const int ioprio = task_ioprio(ioc);
2962 const int ioprio_class = task_ioprio_class(ioc);
2963 struct cfq_queue **async_cfqq = NULL;
2964 struct cfq_queue *cfqq = NULL;
2967 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2972 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2975 * pin the queue now that it's allocated, scheduler exit will prune it
2977 if (!is_sync && !(*async_cfqq)) {
2987 * We drop cfq io contexts lazily, so we may find a dead one.
2990 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2991 struct cfq_io_context *cic)
2993 unsigned long flags;
2995 WARN_ON(!list_empty(&cic->queue_list));
2996 BUG_ON(cic->key != cfqd_dead_key(cfqd));
2998 spin_lock_irqsave(&ioc->lock, flags);
3000 BUG_ON(ioc->ioc_data == cic);
3002 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3003 hlist_del_rcu(&cic->cic_list);
3004 spin_unlock_irqrestore(&ioc->lock, flags);
3009 static struct cfq_io_context *
3010 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3012 struct cfq_io_context *cic;
3013 unsigned long flags;
3021 * we maintain a last-hit cache, to avoid browsing over the tree
3023 cic = rcu_dereference(ioc->ioc_data);
3024 if (cic && cic->key == cfqd) {
3030 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3034 if (unlikely(cic->key != cfqd)) {
3035 cfq_drop_dead_cic(cfqd, ioc, cic);
3040 spin_lock_irqsave(&ioc->lock, flags);
3041 rcu_assign_pointer(ioc->ioc_data, cic);
3042 spin_unlock_irqrestore(&ioc->lock, flags);
3050 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3051 * the process specific cfq io context when entered from the block layer.
3052 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3054 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3055 struct cfq_io_context *cic, gfp_t gfp_mask)
3057 unsigned long flags;
3060 ret = radix_tree_preload(gfp_mask);
3065 spin_lock_irqsave(&ioc->lock, flags);
3066 ret = radix_tree_insert(&ioc->radix_root,
3067 cfqd->cic_index, cic);
3069 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3070 spin_unlock_irqrestore(&ioc->lock, flags);
3072 radix_tree_preload_end();
3075 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3076 list_add(&cic->queue_list, &cfqd->cic_list);
3077 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3082 printk(KERN_ERR "cfq: cic link failed!\n");
3088 * Setup general io context and cfq io context. There can be several cfq
3089 * io contexts per general io context, if this process is doing io to more
3090 * than one device managed by cfq.
3092 static struct cfq_io_context *
3093 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3095 struct io_context *ioc = NULL;
3096 struct cfq_io_context *cic;
3098 might_sleep_if(gfp_mask & __GFP_WAIT);
3100 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3104 cic = cfq_cic_lookup(cfqd, ioc);
3108 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3112 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3116 smp_read_barrier_depends();
3117 if (unlikely(ioc->ioprio_changed))
3118 cfq_ioc_set_ioprio(ioc);
3120 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3121 if (unlikely(ioc->cgroup_changed))
3122 cfq_ioc_set_cgroup(ioc);
3128 put_io_context(ioc);
3133 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3135 unsigned long elapsed = jiffies - cic->last_end_request;
3136 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3138 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3139 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3140 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3144 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3148 sector_t n_sec = blk_rq_sectors(rq);
3149 if (cfqq->last_request_pos) {
3150 if (cfqq->last_request_pos < blk_rq_pos(rq))
3151 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3153 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3156 cfqq->seek_history <<= 1;
3157 if (blk_queue_nonrot(cfqd->queue))
3158 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3160 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3164 * Disable idle window if the process thinks too long or seeks so much that
3168 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3169 struct cfq_io_context *cic)
3171 int old_idle, enable_idle;
3174 * Don't idle for async or idle io prio class
3176 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3179 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3181 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3182 cfq_mark_cfqq_deep(cfqq);
3184 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3186 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3187 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3189 else if (sample_valid(cic->ttime_samples)) {
3190 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3196 if (old_idle != enable_idle) {
3197 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3199 cfq_mark_cfqq_idle_window(cfqq);
3201 cfq_clear_cfqq_idle_window(cfqq);
3206 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3207 * no or if we aren't sure, a 1 will cause a preempt.
3210 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3213 struct cfq_queue *cfqq;
3215 cfqq = cfqd->active_queue;
3219 if (cfq_class_idle(new_cfqq))
3222 if (cfq_class_idle(cfqq))
3226 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3228 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3232 * if the new request is sync, but the currently running queue is
3233 * not, let the sync request have priority.
3235 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3238 if (new_cfqq->cfqg != cfqq->cfqg)
3241 if (cfq_slice_used(cfqq))
3244 /* Allow preemption only if we are idling on sync-noidle tree */
3245 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3246 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3247 new_cfqq->service_tree->count == 2 &&
3248 RB_EMPTY_ROOT(&cfqq->sort_list))
3252 * So both queues are sync. Let the new request get disk time if
3253 * it's a metadata request and the current queue is doing regular IO.
3255 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3259 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3261 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3264 /* An idle queue should not be idle now for some reason */
3265 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3268 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3272 * if this request is as-good as one we would expect from the
3273 * current cfqq, let it preempt
3275 if (cfq_rq_close(cfqd, cfqq, rq))
3282 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3283 * let it have half of its nominal slice.
3285 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3287 struct cfq_queue *old_cfqq = cfqd->active_queue;
3289 cfq_log_cfqq(cfqd, cfqq, "preempt");
3290 cfq_slice_expired(cfqd, 1);
3293 * workload type is changed, don't save slice, otherwise preempt
3296 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3297 cfqq->cfqg->saved_workload_slice = 0;
3300 * Put the new queue at the front of the of the current list,
3301 * so we know that it will be selected next.
3303 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3305 cfq_service_tree_add(cfqd, cfqq, 1);
3307 cfqq->slice_end = 0;
3308 cfq_mark_cfqq_slice_new(cfqq);
3312 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3313 * something we should do about it
3316 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3319 struct cfq_io_context *cic = RQ_CIC(rq);
3322 if (rq->cmd_flags & REQ_META)
3323 cfqq->meta_pending++;
3325 cfq_update_io_thinktime(cfqd, cic);
3326 cfq_update_io_seektime(cfqd, cfqq, rq);
3327 cfq_update_idle_window(cfqd, cfqq, cic);
3329 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3331 if (cfqq == cfqd->active_queue) {
3333 * Remember that we saw a request from this process, but
3334 * don't start queuing just yet. Otherwise we risk seeing lots
3335 * of tiny requests, because we disrupt the normal plugging
3336 * and merging. If the request is already larger than a single
3337 * page, let it rip immediately. For that case we assume that
3338 * merging is already done. Ditto for a busy system that
3339 * has other work pending, don't risk delaying until the
3340 * idle timer unplug to continue working.
3342 if (cfq_cfqq_wait_request(cfqq)) {
3343 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3344 cfqd->busy_queues > 1) {
3345 cfq_del_timer(cfqd, cfqq);
3346 cfq_clear_cfqq_wait_request(cfqq);
3347 __blk_run_queue(cfqd->queue, false);
3349 cfq_blkiocg_update_idle_time_stats(
3351 cfq_mark_cfqq_must_dispatch(cfqq);
3354 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3356 * not the active queue - expire current slice if it is
3357 * idle and has expired it's mean thinktime or this new queue
3358 * has some old slice time left and is of higher priority or
3359 * this new queue is RT and the current one is BE
3361 cfq_preempt_queue(cfqd, cfqq);
3362 __blk_run_queue(cfqd->queue, false);
3366 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3368 struct cfq_data *cfqd = q->elevator->elevator_data;
3369 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3371 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3372 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3374 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3375 list_add_tail(&rq->queuelist, &cfqq->fifo);
3377 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3378 &cfqd->serving_group->blkg, rq_data_dir(rq),
3380 cfq_rq_enqueued(cfqd, cfqq, rq);
3384 * Update hw_tag based on peak queue depth over 50 samples under
3387 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3389 struct cfq_queue *cfqq = cfqd->active_queue;
3391 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3392 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3394 if (cfqd->hw_tag == 1)
3397 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3398 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3402 * If active queue hasn't enough requests and can idle, cfq might not
3403 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3406 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3407 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3408 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3411 if (cfqd->hw_tag_samples++ < 50)
3414 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3420 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3422 struct cfq_io_context *cic = cfqd->active_cic;
3424 /* If the queue already has requests, don't wait */
3425 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3428 /* If there are other queues in the group, don't wait */
3429 if (cfqq->cfqg->nr_cfqq > 1)
3432 if (cfq_slice_used(cfqq))
3435 /* if slice left is less than think time, wait busy */
3436 if (cic && sample_valid(cic->ttime_samples)
3437 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3441 * If think times is less than a jiffy than ttime_mean=0 and above
3442 * will not be true. It might happen that slice has not expired yet
3443 * but will expire soon (4-5 ns) during select_queue(). To cover the
3444 * case where think time is less than a jiffy, mark the queue wait
3445 * busy if only 1 jiffy is left in the slice.
3447 if (cfqq->slice_end - jiffies == 1)
3453 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3455 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3456 struct cfq_data *cfqd = cfqq->cfqd;
3457 const int sync = rq_is_sync(rq);
3461 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3462 !!(rq->cmd_flags & REQ_NOIDLE));
3464 cfq_update_hw_tag(cfqd);
3466 WARN_ON(!cfqd->rq_in_driver);
3467 WARN_ON(!cfqq->dispatched);
3468 cfqd->rq_in_driver--;
3470 (RQ_CFQG(rq))->dispatched--;
3471 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3472 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3473 rq_data_dir(rq), rq_is_sync(rq));
3475 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3478 RQ_CIC(rq)->last_end_request = now;
3479 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3480 cfqd->last_delayed_sync = now;
3484 * If this is the active queue, check if it needs to be expired,
3485 * or if we want to idle in case it has no pending requests.
3487 if (cfqd->active_queue == cfqq) {
3488 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3490 if (cfq_cfqq_slice_new(cfqq)) {
3491 cfq_set_prio_slice(cfqd, cfqq);
3492 cfq_clear_cfqq_slice_new(cfqq);
3496 * Should we wait for next request to come in before we expire
3499 if (cfq_should_wait_busy(cfqd, cfqq)) {
3500 unsigned long extend_sl = cfqd->cfq_slice_idle;
3501 if (!cfqd->cfq_slice_idle)
3502 extend_sl = cfqd->cfq_group_idle;
3503 cfqq->slice_end = jiffies + extend_sl;
3504 cfq_mark_cfqq_wait_busy(cfqq);
3505 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3509 * Idling is not enabled on:
3511 * - idle-priority queues
3513 * - queues with still some requests queued
3514 * - when there is a close cooperator
3516 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3517 cfq_slice_expired(cfqd, 1);
3518 else if (sync && cfqq_empty &&
3519 !cfq_close_cooperator(cfqd, cfqq)) {
3520 cfq_arm_slice_timer(cfqd);
3524 if (!cfqd->rq_in_driver)
3525 cfq_schedule_dispatch(cfqd);
3529 * we temporarily boost lower priority queues if they are holding fs exclusive
3530 * resources. they are boosted to normal prio (CLASS_BE/4)
3532 static void cfq_prio_boost(struct cfq_queue *cfqq)
3534 if (has_fs_excl()) {
3536 * boost idle prio on transactions that would lock out other
3537 * users of the filesystem
3539 if (cfq_class_idle(cfqq))
3540 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3541 if (cfqq->ioprio > IOPRIO_NORM)
3542 cfqq->ioprio = IOPRIO_NORM;
3545 * unboost the queue (if needed)
3547 cfqq->ioprio_class = cfqq->org_ioprio_class;
3548 cfqq->ioprio = cfqq->org_ioprio;
3552 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3554 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3555 cfq_mark_cfqq_must_alloc_slice(cfqq);
3556 return ELV_MQUEUE_MUST;
3559 return ELV_MQUEUE_MAY;
3562 static int cfq_may_queue(struct request_queue *q, int rw)
3564 struct cfq_data *cfqd = q->elevator->elevator_data;
3565 struct task_struct *tsk = current;
3566 struct cfq_io_context *cic;
3567 struct cfq_queue *cfqq;
3570 * don't force setup of a queue from here, as a call to may_queue
3571 * does not necessarily imply that a request actually will be queued.
3572 * so just lookup a possibly existing queue, or return 'may queue'
3575 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3577 return ELV_MQUEUE_MAY;
3579 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3581 cfq_init_prio_data(cfqq, cic->ioc);
3582 cfq_prio_boost(cfqq);
3584 return __cfq_may_queue(cfqq);
3587 return ELV_MQUEUE_MAY;
3591 * queue lock held here
3593 static void cfq_put_request(struct request *rq)
3595 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3598 const int rw = rq_data_dir(rq);
3600 BUG_ON(!cfqq->allocated[rw]);
3601 cfqq->allocated[rw]--;
3603 put_io_context(RQ_CIC(rq)->ioc);
3605 rq->elevator_private[0] = NULL;
3606 rq->elevator_private[1] = NULL;
3608 /* Put down rq reference on cfqg */
3609 cfq_put_cfqg(RQ_CFQG(rq));
3610 rq->elevator_private[2] = NULL;
3612 cfq_put_queue(cfqq);
3616 static struct cfq_queue *
3617 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3618 struct cfq_queue *cfqq)
3620 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3621 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3622 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3623 cfq_put_queue(cfqq);
3624 return cic_to_cfqq(cic, 1);
3628 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3629 * was the last process referring to said cfqq.
3631 static struct cfq_queue *
3632 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3634 if (cfqq_process_refs(cfqq) == 1) {
3635 cfqq->pid = current->pid;
3636 cfq_clear_cfqq_coop(cfqq);
3637 cfq_clear_cfqq_split_coop(cfqq);
3641 cic_set_cfqq(cic, NULL, 1);
3643 cfq_put_cooperator(cfqq);
3645 cfq_put_queue(cfqq);
3649 * Allocate cfq data structures associated with this request.
3652 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3654 struct cfq_data *cfqd = q->elevator->elevator_data;
3655 struct cfq_io_context *cic;
3656 const int rw = rq_data_dir(rq);
3657 const bool is_sync = rq_is_sync(rq);
3658 struct cfq_queue *cfqq;
3659 unsigned long flags;
3661 might_sleep_if(gfp_mask & __GFP_WAIT);
3663 cic = cfq_get_io_context(cfqd, gfp_mask);
3665 spin_lock_irqsave(q->queue_lock, flags);
3671 cfqq = cic_to_cfqq(cic, is_sync);
3672 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3673 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3674 cic_set_cfqq(cic, cfqq, is_sync);
3677 * If the queue was seeky for too long, break it apart.
3679 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3680 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3681 cfqq = split_cfqq(cic, cfqq);
3687 * Check to see if this queue is scheduled to merge with
3688 * another, closely cooperating queue. The merging of
3689 * queues happens here as it must be done in process context.
3690 * The reference on new_cfqq was taken in merge_cfqqs.
3693 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3696 cfqq->allocated[rw]++;
3699 rq->elevator_private[0] = cic;
3700 rq->elevator_private[1] = cfqq;
3701 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3702 spin_unlock_irqrestore(q->queue_lock, flags);
3707 put_io_context(cic->ioc);
3709 cfq_schedule_dispatch(cfqd);
3710 spin_unlock_irqrestore(q->queue_lock, flags);
3711 cfq_log(cfqd, "set_request fail");
3715 static void cfq_kick_queue(struct work_struct *work)
3717 struct cfq_data *cfqd =
3718 container_of(work, struct cfq_data, unplug_work);
3719 struct request_queue *q = cfqd->queue;
3721 spin_lock_irq(q->queue_lock);
3722 __blk_run_queue(cfqd->queue, false);
3723 spin_unlock_irq(q->queue_lock);
3727 * Timer running if the active_queue is currently idling inside its time slice
3729 static void cfq_idle_slice_timer(unsigned long data)
3731 struct cfq_data *cfqd = (struct cfq_data *) data;
3732 struct cfq_queue *cfqq;
3733 unsigned long flags;
3736 cfq_log(cfqd, "idle timer fired");
3738 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3740 cfqq = cfqd->active_queue;
3745 * We saw a request before the queue expired, let it through
3747 if (cfq_cfqq_must_dispatch(cfqq))
3753 if (cfq_slice_used(cfqq))
3757 * only expire and reinvoke request handler, if there are
3758 * other queues with pending requests
3760 if (!cfqd->busy_queues)
3764 * not expired and it has a request pending, let it dispatch
3766 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3770 * Queue depth flag is reset only when the idle didn't succeed
3772 cfq_clear_cfqq_deep(cfqq);
3775 cfq_slice_expired(cfqd, timed_out);
3777 cfq_schedule_dispatch(cfqd);
3779 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3782 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3784 del_timer_sync(&cfqd->idle_slice_timer);
3785 cancel_work_sync(&cfqd->unplug_work);
3788 static void cfq_put_async_queues(struct cfq_data *cfqd)
3792 for (i = 0; i < IOPRIO_BE_NR; i++) {
3793 if (cfqd->async_cfqq[0][i])
3794 cfq_put_queue(cfqd->async_cfqq[0][i]);
3795 if (cfqd->async_cfqq[1][i])
3796 cfq_put_queue(cfqd->async_cfqq[1][i]);
3799 if (cfqd->async_idle_cfqq)
3800 cfq_put_queue(cfqd->async_idle_cfqq);
3803 static void cfq_cfqd_free(struct rcu_head *head)
3805 kfree(container_of(head, struct cfq_data, rcu));
3808 static void cfq_exit_queue(struct elevator_queue *e)
3810 struct cfq_data *cfqd = e->elevator_data;
3811 struct request_queue *q = cfqd->queue;
3813 cfq_shutdown_timer_wq(cfqd);
3815 spin_lock_irq(q->queue_lock);
3817 if (cfqd->active_queue)
3818 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3820 while (!list_empty(&cfqd->cic_list)) {
3821 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3822 struct cfq_io_context,
3825 __cfq_exit_single_io_context(cfqd, cic);
3828 cfq_put_async_queues(cfqd);
3829 cfq_release_cfq_groups(cfqd);
3830 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3832 spin_unlock_irq(q->queue_lock);
3834 cfq_shutdown_timer_wq(cfqd);
3836 spin_lock(&cic_index_lock);
3837 ida_remove(&cic_index_ida, cfqd->cic_index);
3838 spin_unlock(&cic_index_lock);
3840 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3841 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3844 static int cfq_alloc_cic_index(void)
3849 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3852 spin_lock(&cic_index_lock);
3853 error = ida_get_new(&cic_index_ida, &index);
3854 spin_unlock(&cic_index_lock);
3855 if (error && error != -EAGAIN)
3862 static void *cfq_init_queue(struct request_queue *q)
3864 struct cfq_data *cfqd;
3866 struct cfq_group *cfqg;
3867 struct cfq_rb_root *st;
3869 i = cfq_alloc_cic_index();
3873 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3878 * Don't need take queue_lock in the routine, since we are
3879 * initializing the ioscheduler, and nobody is using cfqd
3881 cfqd->cic_index = i;
3883 /* Init root service tree */
3884 cfqd->grp_service_tree = CFQ_RB_ROOT;
3886 /* Init root group */
3887 cfqg = &cfqd->root_group;
3888 for_each_cfqg_st(cfqg, i, j, st)
3890 RB_CLEAR_NODE(&cfqg->rb_node);
3892 /* Give preference to root group over other groups */
3893 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3895 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3897 * Take a reference to root group which we never drop. This is just
3898 * to make sure that cfq_put_cfqg() does not try to kfree root group
3902 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3907 * Not strictly needed (since RB_ROOT just clears the node and we
3908 * zeroed cfqd on alloc), but better be safe in case someone decides
3909 * to add magic to the rb code
3911 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3912 cfqd->prio_trees[i] = RB_ROOT;
3915 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3916 * Grab a permanent reference to it, so that the normal code flow
3917 * will not attempt to free it.
3919 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3920 cfqd->oom_cfqq.ref++;
3921 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3923 INIT_LIST_HEAD(&cfqd->cic_list);
3927 init_timer(&cfqd->idle_slice_timer);
3928 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3929 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3931 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3933 cfqd->cfq_quantum = cfq_quantum;
3934 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3935 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3936 cfqd->cfq_back_max = cfq_back_max;
3937 cfqd->cfq_back_penalty = cfq_back_penalty;
3938 cfqd->cfq_slice[0] = cfq_slice_async;
3939 cfqd->cfq_slice[1] = cfq_slice_sync;
3940 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3941 cfqd->cfq_slice_idle = cfq_slice_idle;
3942 cfqd->cfq_group_idle = cfq_group_idle;
3943 cfqd->cfq_latency = 1;
3946 * we optimistically start assuming sync ops weren't delayed in last
3947 * second, in order to have larger depth for async operations.
3949 cfqd->last_delayed_sync = jiffies - HZ;
3953 static void cfq_slab_kill(void)
3956 * Caller already ensured that pending RCU callbacks are completed,
3957 * so we should have no busy allocations at this point.
3960 kmem_cache_destroy(cfq_pool);
3962 kmem_cache_destroy(cfq_ioc_pool);
3965 static int __init cfq_slab_setup(void)
3967 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3971 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3982 * sysfs parts below -->
3985 cfq_var_show(unsigned int var, char *page)
3987 return sprintf(page, "%d\n", var);
3991 cfq_var_store(unsigned int *var, const char *page, size_t count)
3993 char *p = (char *) page;
3995 *var = simple_strtoul(p, &p, 10);
3999 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4000 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4002 struct cfq_data *cfqd = e->elevator_data; \
4003 unsigned int __data = __VAR; \
4005 __data = jiffies_to_msecs(__data); \
4006 return cfq_var_show(__data, (page)); \
4008 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4009 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4010 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4011 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4012 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4013 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4014 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4015 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4016 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4017 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4018 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4019 #undef SHOW_FUNCTION
4021 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4022 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4024 struct cfq_data *cfqd = e->elevator_data; \
4025 unsigned int __data; \
4026 int ret = cfq_var_store(&__data, (page), count); \
4027 if (__data < (MIN)) \
4029 else if (__data > (MAX)) \
4032 *(__PTR) = msecs_to_jiffies(__data); \
4034 *(__PTR) = __data; \
4037 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4038 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4040 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4042 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4043 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4045 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4046 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4047 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4048 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4049 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4051 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4052 #undef STORE_FUNCTION
4054 #define CFQ_ATTR(name) \
4055 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4057 static struct elv_fs_entry cfq_attrs[] = {
4059 CFQ_ATTR(fifo_expire_sync),
4060 CFQ_ATTR(fifo_expire_async),
4061 CFQ_ATTR(back_seek_max),
4062 CFQ_ATTR(back_seek_penalty),
4063 CFQ_ATTR(slice_sync),
4064 CFQ_ATTR(slice_async),
4065 CFQ_ATTR(slice_async_rq),
4066 CFQ_ATTR(slice_idle),
4067 CFQ_ATTR(group_idle),
4068 CFQ_ATTR(low_latency),
4072 static struct elevator_type iosched_cfq = {
4074 .elevator_merge_fn = cfq_merge,
4075 .elevator_merged_fn = cfq_merged_request,
4076 .elevator_merge_req_fn = cfq_merged_requests,
4077 .elevator_allow_merge_fn = cfq_allow_merge,
4078 .elevator_bio_merged_fn = cfq_bio_merged,
4079 .elevator_dispatch_fn = cfq_dispatch_requests,
4080 .elevator_add_req_fn = cfq_insert_request,
4081 .elevator_activate_req_fn = cfq_activate_request,
4082 .elevator_deactivate_req_fn = cfq_deactivate_request,
4083 .elevator_queue_empty_fn = cfq_queue_empty,
4084 .elevator_completed_req_fn = cfq_completed_request,
4085 .elevator_former_req_fn = elv_rb_former_request,
4086 .elevator_latter_req_fn = elv_rb_latter_request,
4087 .elevator_set_req_fn = cfq_set_request,
4088 .elevator_put_req_fn = cfq_put_request,
4089 .elevator_may_queue_fn = cfq_may_queue,
4090 .elevator_init_fn = cfq_init_queue,
4091 .elevator_exit_fn = cfq_exit_queue,
4092 .trim = cfq_free_io_context,
4094 .elevator_attrs = cfq_attrs,
4095 .elevator_name = "cfq",
4096 .elevator_owner = THIS_MODULE,
4099 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4100 static struct blkio_policy_type blkio_policy_cfq = {
4102 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4103 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4105 .plid = BLKIO_POLICY_PROP,
4108 static struct blkio_policy_type blkio_policy_cfq;
4111 static int __init cfq_init(void)
4114 * could be 0 on HZ < 1000 setups
4116 if (!cfq_slice_async)
4117 cfq_slice_async = 1;
4118 if (!cfq_slice_idle)
4121 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4122 if (!cfq_group_idle)
4127 if (cfq_slab_setup())
4130 elv_register(&iosched_cfq);
4131 blkio_policy_register(&blkio_policy_cfq);
4136 static void __exit cfq_exit(void)
4138 DECLARE_COMPLETION_ONSTACK(all_gone);
4139 blkio_policy_unregister(&blkio_policy_cfq);
4140 elv_unregister(&iosched_cfq);
4141 ioc_gone = &all_gone;
4142 /* ioc_gone's update must be visible before reading ioc_count */
4146 * this also protects us from entering cfq_slab_kill() with
4147 * pending RCU callbacks
4149 if (elv_ioc_count_read(cfq_ioc_count))
4150 wait_for_completion(&all_gone);
4151 ida_destroy(&cic_index_ida);
4155 module_init(cfq_init);
4156 module_exit(cfq_exit);
4158 MODULE_AUTHOR("Jens Axboe");
4159 MODULE_LICENSE("GPL");
4160 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");