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 */
181 unsigned int new_weight;
184 /* number of cfqq currently on this group */
188 * Per group busy queus average. Useful for workload slice calc. We
189 * create the array for each prio class but at run time it is used
190 * only for RT and BE class and slot for IDLE class remains unused.
191 * This is primarily done to avoid confusion and a gcc warning.
193 unsigned int busy_queues_avg[CFQ_PRIO_NR];
195 * rr lists of queues with requests. We maintain service trees for
196 * RT and BE classes. These trees are subdivided in subclasses
197 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
198 * class there is no subclassification and all the cfq queues go on
199 * a single tree service_tree_idle.
200 * Counts are embedded in the cfq_rb_root
202 struct cfq_rb_root service_trees[2][3];
203 struct cfq_rb_root service_tree_idle;
205 unsigned long saved_workload_slice;
206 enum wl_type_t saved_workload;
207 enum wl_prio_t saved_serving_prio;
208 struct blkio_group blkg;
209 #ifdef CONFIG_CFQ_GROUP_IOSCHED
210 struct hlist_node cfqd_node;
213 /* number of requests that are on the dispatch list or inside driver */
218 * Per block device queue structure
221 struct request_queue *queue;
222 /* Root service tree for cfq_groups */
223 struct cfq_rb_root grp_service_tree;
224 struct cfq_group root_group;
227 * The priority currently being served
229 enum wl_prio_t serving_prio;
230 enum wl_type_t serving_type;
231 unsigned long workload_expires;
232 struct cfq_group *serving_group;
235 * Each priority tree is sorted by next_request position. These
236 * trees are used when determining if two or more queues are
237 * interleaving requests (see cfq_close_cooperator).
239 struct rb_root prio_trees[CFQ_PRIO_LISTS];
241 unsigned int busy_queues;
242 unsigned int busy_sync_queues;
248 * queue-depth detection
254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
258 int hw_tag_est_depth;
259 unsigned int hw_tag_samples;
262 * idle window management
264 struct timer_list idle_slice_timer;
265 struct work_struct unplug_work;
267 struct cfq_queue *active_queue;
268 struct cfq_io_context *active_cic;
271 * async queue for each priority case
273 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
274 struct cfq_queue *async_idle_cfqq;
276 sector_t last_position;
279 * tunables, see top of file
281 unsigned int cfq_quantum;
282 unsigned int cfq_fifo_expire[2];
283 unsigned int cfq_back_penalty;
284 unsigned int cfq_back_max;
285 unsigned int cfq_slice[2];
286 unsigned int cfq_slice_async_rq;
287 unsigned int cfq_slice_idle;
288 unsigned int cfq_group_idle;
289 unsigned int cfq_latency;
291 unsigned int cic_index;
292 struct list_head cic_list;
295 * Fallback dummy cfqq for extreme OOM conditions
297 struct cfq_queue oom_cfqq;
299 unsigned long last_delayed_sync;
301 /* List of cfq groups being managed on this device*/
302 struct hlist_head cfqg_list;
306 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
308 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
315 if (prio == IDLE_WORKLOAD)
316 return &cfqg->service_tree_idle;
318 return &cfqg->service_trees[prio][type];
321 enum cfqq_state_flags {
322 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
323 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
324 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
325 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
326 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
327 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
328 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
329 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
330 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
331 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
332 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
333 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
334 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
337 #define CFQ_CFQQ_FNS(name) \
338 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
340 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
342 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
344 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
346 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
348 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
352 CFQ_CFQQ_FNS(wait_request);
353 CFQ_CFQQ_FNS(must_dispatch);
354 CFQ_CFQQ_FNS(must_alloc_slice);
355 CFQ_CFQQ_FNS(fifo_expire);
356 CFQ_CFQQ_FNS(idle_window);
357 CFQ_CFQQ_FNS(prio_changed);
358 CFQ_CFQQ_FNS(slice_new);
361 CFQ_CFQQ_FNS(split_coop);
363 CFQ_CFQQ_FNS(wait_busy);
366 #ifdef CONFIG_CFQ_GROUP_IOSCHED
367 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
368 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
369 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
370 blkg_path(&(cfqq)->cfqg->blkg), ##args);
372 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
373 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
374 blkg_path(&(cfqg)->blkg), ##args); \
377 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
378 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
379 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
381 #define cfq_log(cfqd, fmt, args...) \
382 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
384 /* Traverses through cfq group service trees */
385 #define for_each_cfqg_st(cfqg, i, j, st) \
386 for (i = 0; i <= IDLE_WORKLOAD; i++) \
387 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
388 : &cfqg->service_tree_idle; \
389 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
390 (i == IDLE_WORKLOAD && j == 0); \
391 j++, st = i < IDLE_WORKLOAD ? \
392 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool iops_mode(struct cfq_data *cfqd)
398 * If we are not idling on queues and it is a NCQ drive, parallel
399 * execution of requests is on and measuring time is not possible
400 * in most of the cases until and unless we drive shallower queue
401 * depths and that becomes a performance bottleneck. In such cases
402 * switch to start providing fairness in terms of number of IOs.
404 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
410 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
412 if (cfq_class_idle(cfqq))
413 return IDLE_WORKLOAD;
414 if (cfq_class_rt(cfqq))
420 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
422 if (!cfq_cfqq_sync(cfqq))
423 return ASYNC_WORKLOAD;
424 if (!cfq_cfqq_idle_window(cfqq))
425 return SYNC_NOIDLE_WORKLOAD;
426 return SYNC_WORKLOAD;
429 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
430 struct cfq_data *cfqd,
431 struct cfq_group *cfqg)
433 if (wl == IDLE_WORKLOAD)
434 return cfqg->service_tree_idle.count;
436 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
437 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
438 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
441 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
442 struct cfq_group *cfqg)
444 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
445 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
448 static void cfq_dispatch_insert(struct request_queue *, struct request *);
449 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
450 struct io_context *, gfp_t);
451 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
452 struct io_context *);
454 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
457 return cic->cfqq[is_sync];
460 static inline void cic_set_cfqq(struct cfq_io_context *cic,
461 struct cfq_queue *cfqq, bool is_sync)
463 cic->cfqq[is_sync] = cfqq;
466 #define CIC_DEAD_KEY 1ul
467 #define CIC_DEAD_INDEX_SHIFT 1
469 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
471 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
474 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
476 struct cfq_data *cfqd = cic->key;
478 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
485 * We regard a request as SYNC, if it's either a read or has the SYNC bit
486 * set (in which case it could also be direct WRITE).
488 static inline bool cfq_bio_sync(struct bio *bio)
490 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
494 * scheduler run of queue, if there are requests pending and no one in the
495 * driver that will restart queueing
497 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
499 if (cfqd->busy_queues) {
500 cfq_log(cfqd, "schedule dispatch");
501 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
506 * Scale schedule slice based on io priority. Use the sync time slice only
507 * if a queue is marked sync and has sync io queued. A sync queue with async
508 * io only, should not get full sync slice length.
510 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
513 const int base_slice = cfqd->cfq_slice[sync];
515 WARN_ON(prio >= IOPRIO_BE_NR);
517 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
521 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
523 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
526 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
528 u64 d = delta << CFQ_SERVICE_SHIFT;
530 d = d * BLKIO_WEIGHT_DEFAULT;
531 do_div(d, cfqg->weight);
535 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
537 s64 delta = (s64)(vdisktime - min_vdisktime);
539 min_vdisktime = vdisktime;
541 return min_vdisktime;
544 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
546 s64 delta = (s64)(vdisktime - min_vdisktime);
548 min_vdisktime = vdisktime;
550 return min_vdisktime;
553 static void update_min_vdisktime(struct cfq_rb_root *st)
555 struct cfq_group *cfqg;
558 cfqg = rb_entry_cfqg(st->left);
559 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
565 * get averaged number of queues of RT/BE priority.
566 * average is updated, with a formula that gives more weight to higher numbers,
567 * to quickly follows sudden increases and decrease slowly
570 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
571 struct cfq_group *cfqg, bool rt)
573 unsigned min_q, max_q;
574 unsigned mult = cfq_hist_divisor - 1;
575 unsigned round = cfq_hist_divisor / 2;
576 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
578 min_q = min(cfqg->busy_queues_avg[rt], busy);
579 max_q = max(cfqg->busy_queues_avg[rt], busy);
580 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
582 return cfqg->busy_queues_avg[rt];
585 static inline unsigned
586 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
588 struct cfq_rb_root *st = &cfqd->grp_service_tree;
590 return cfq_target_latency * cfqg->weight / st->total_weight;
593 static inline unsigned
594 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
596 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
597 if (cfqd->cfq_latency) {
599 * interested queues (we consider only the ones with the same
600 * priority class in the cfq group)
602 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
604 unsigned sync_slice = cfqd->cfq_slice[1];
605 unsigned expect_latency = sync_slice * iq;
606 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
608 if (expect_latency > group_slice) {
609 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
610 /* scale low_slice according to IO priority
611 * and sync vs async */
613 min(slice, base_low_slice * slice / sync_slice);
614 /* the adapted slice value is scaled to fit all iqs
615 * into the target latency */
616 slice = max(slice * group_slice / expect_latency,
624 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
626 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
628 cfqq->slice_start = jiffies;
629 cfqq->slice_end = jiffies + slice;
630 cfqq->allocated_slice = slice;
631 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
635 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
636 * isn't valid until the first request from the dispatch is activated
637 * and the slice time set.
639 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
641 if (cfq_cfqq_slice_new(cfqq))
643 if (time_before(jiffies, cfqq->slice_end))
650 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
651 * We choose the request that is closest to the head right now. Distance
652 * behind the head is penalized and only allowed to a certain extent.
654 static struct request *
655 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
657 sector_t s1, s2, d1 = 0, d2 = 0;
658 unsigned long back_max;
659 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
660 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
661 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
663 if (rq1 == NULL || rq1 == rq2)
668 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
670 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
672 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
674 else if ((rq2->cmd_flags & REQ_META) &&
675 !(rq1->cmd_flags & REQ_META))
678 s1 = blk_rq_pos(rq1);
679 s2 = blk_rq_pos(rq2);
682 * by definition, 1KiB is 2 sectors
684 back_max = cfqd->cfq_back_max * 2;
687 * Strict one way elevator _except_ in the case where we allow
688 * short backward seeks which are biased as twice the cost of a
689 * similar forward seek.
693 else if (s1 + back_max >= last)
694 d1 = (last - s1) * cfqd->cfq_back_penalty;
696 wrap |= CFQ_RQ1_WRAP;
700 else if (s2 + back_max >= last)
701 d2 = (last - s2) * cfqd->cfq_back_penalty;
703 wrap |= CFQ_RQ2_WRAP;
705 /* Found required data */
708 * By doing switch() on the bit mask "wrap" we avoid having to
709 * check two variables for all permutations: --> faster!
712 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
728 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
731 * Since both rqs are wrapped,
732 * start with the one that's further behind head
733 * (--> only *one* back seek required),
734 * since back seek takes more time than forward.
744 * The below is leftmost cache rbtree addon
746 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
748 /* Service tree is empty */
753 root->left = rb_first(&root->rb);
756 return rb_entry(root->left, struct cfq_queue, rb_node);
761 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
764 root->left = rb_first(&root->rb);
767 return rb_entry_cfqg(root->left);
772 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
778 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
782 rb_erase_init(n, &root->rb);
787 * would be nice to take fifo expire time into account as well
789 static struct request *
790 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
791 struct request *last)
793 struct rb_node *rbnext = rb_next(&last->rb_node);
794 struct rb_node *rbprev = rb_prev(&last->rb_node);
795 struct request *next = NULL, *prev = NULL;
797 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
800 prev = rb_entry_rq(rbprev);
803 next = rb_entry_rq(rbnext);
805 rbnext = rb_first(&cfqq->sort_list);
806 if (rbnext && rbnext != &last->rb_node)
807 next = rb_entry_rq(rbnext);
810 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
813 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
814 struct cfq_queue *cfqq)
817 * just an approximation, should be ok.
819 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
820 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
824 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
826 return cfqg->vdisktime - st->min_vdisktime;
830 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
832 struct rb_node **node = &st->rb.rb_node;
833 struct rb_node *parent = NULL;
834 struct cfq_group *__cfqg;
835 s64 key = cfqg_key(st, cfqg);
838 while (*node != NULL) {
840 __cfqg = rb_entry_cfqg(parent);
842 if (key < cfqg_key(st, __cfqg))
843 node = &parent->rb_left;
845 node = &parent->rb_right;
851 st->left = &cfqg->rb_node;
853 rb_link_node(&cfqg->rb_node, parent, node);
854 rb_insert_color(&cfqg->rb_node, &st->rb);
858 cfq_update_group_weight(struct cfq_group *cfqg)
860 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
861 if (cfqg->needs_update) {
862 cfqg->weight = cfqg->new_weight;
863 cfqg->needs_update = false;
868 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
870 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
872 cfq_update_group_weight(cfqg);
873 __cfq_group_service_tree_add(st, cfqg);
874 st->total_weight += cfqg->weight;
878 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
880 struct cfq_rb_root *st = &cfqd->grp_service_tree;
881 struct cfq_group *__cfqg;
885 if (!RB_EMPTY_NODE(&cfqg->rb_node))
889 * Currently put the group at the end. Later implement something
890 * so that groups get lesser vtime based on their weights, so that
891 * if group does not loose all if it was not continously backlogged.
893 n = rb_last(&st->rb);
895 __cfqg = rb_entry_cfqg(n);
896 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
898 cfqg->vdisktime = st->min_vdisktime;
899 cfq_group_service_tree_add(st, cfqg);
903 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
905 st->total_weight -= cfqg->weight;
906 if (!RB_EMPTY_NODE(&cfqg->rb_node))
907 cfq_rb_erase(&cfqg->rb_node, st);
911 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
913 struct cfq_rb_root *st = &cfqd->grp_service_tree;
915 BUG_ON(cfqg->nr_cfqq < 1);
918 /* If there are other cfq queues under this group, don't delete it */
922 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
923 cfq_group_service_tree_del(st, cfqg);
924 cfqg->saved_workload_slice = 0;
925 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
928 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
929 unsigned int *unaccounted_time)
931 unsigned int slice_used;
934 * Queue got expired before even a single request completed or
935 * got expired immediately after first request completion.
937 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
939 * Also charge the seek time incurred to the group, otherwise
940 * if there are mutiple queues in the group, each can dispatch
941 * a single request on seeky media and cause lots of seek time
942 * and group will never know it.
944 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
947 slice_used = jiffies - cfqq->slice_start;
948 if (slice_used > cfqq->allocated_slice) {
949 *unaccounted_time = slice_used - cfqq->allocated_slice;
950 slice_used = cfqq->allocated_slice;
952 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
953 *unaccounted_time += cfqq->slice_start -
954 cfqq->dispatch_start;
960 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
961 struct cfq_queue *cfqq)
963 struct cfq_rb_root *st = &cfqd->grp_service_tree;
964 unsigned int used_sl, charge, unaccounted_sl = 0;
965 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
966 - cfqg->service_tree_idle.count;
969 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
972 charge = cfqq->slice_dispatch;
973 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
974 charge = cfqq->allocated_slice;
976 /* Can't update vdisktime while group is on service tree */
977 cfq_group_service_tree_del(st, cfqg);
978 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
979 /* If a new weight was requested, update now, off tree */
980 cfq_group_service_tree_add(st, cfqg);
982 /* This group is being expired. Save the context */
983 if (time_after(cfqd->workload_expires, jiffies)) {
984 cfqg->saved_workload_slice = cfqd->workload_expires
986 cfqg->saved_workload = cfqd->serving_type;
987 cfqg->saved_serving_prio = cfqd->serving_prio;
989 cfqg->saved_workload_slice = 0;
991 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
993 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
994 " sect=%u", used_sl, cfqq->slice_dispatch, charge,
995 iops_mode(cfqd), cfqq->nr_sectors);
996 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
998 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
1001 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1002 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
1005 return container_of(blkg, struct cfq_group, blkg);
1009 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1010 unsigned int weight)
1012 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1013 cfqg->new_weight = weight;
1014 cfqg->needs_update = true;
1017 static struct cfq_group *
1018 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
1020 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1021 struct cfq_group *cfqg = NULL;
1024 struct cfq_rb_root *st;
1025 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1026 unsigned int major, minor;
1028 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1029 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1030 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1031 cfqg->blkg.dev = MKDEV(major, minor);
1034 if (cfqg || !create)
1037 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1041 for_each_cfqg_st(cfqg, i, j, st)
1043 RB_CLEAR_NODE(&cfqg->rb_node);
1046 * Take the initial reference that will be released on destroy
1047 * This can be thought of a joint reference by cgroup and
1048 * elevator which will be dropped by either elevator exit
1049 * or cgroup deletion path depending on who is exiting first.
1054 * Add group onto cgroup list. It might happen that bdi->dev is
1055 * not initialized yet. Initialize this new group without major
1056 * and minor info and this info will be filled in once a new thread
1057 * comes for IO. See code above.
1060 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1061 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1062 MKDEV(major, minor));
1064 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1067 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1069 /* Add group on cfqd list */
1070 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1077 * Search for the cfq group current task belongs to. If create = 1, then also
1078 * create the cfq group if it does not exist. request_queue lock must be held.
1080 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1082 struct cgroup *cgroup;
1083 struct cfq_group *cfqg = NULL;
1086 cgroup = task_cgroup(current, blkio_subsys_id);
1087 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1088 if (!cfqg && create)
1089 cfqg = &cfqd->root_group;
1094 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1100 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1102 /* Currently, all async queues are mapped to root group */
1103 if (!cfq_cfqq_sync(cfqq))
1104 cfqg = &cfqq->cfqd->root_group;
1107 /* cfqq reference on cfqg */
1111 static void cfq_put_cfqg(struct cfq_group *cfqg)
1113 struct cfq_rb_root *st;
1116 BUG_ON(cfqg->ref <= 0);
1120 for_each_cfqg_st(cfqg, i, j, st)
1121 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1125 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1127 /* Something wrong if we are trying to remove same group twice */
1128 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1130 hlist_del_init(&cfqg->cfqd_node);
1133 * Put the reference taken at the time of creation so that when all
1134 * queues are gone, group can be destroyed.
1139 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1141 struct hlist_node *pos, *n;
1142 struct cfq_group *cfqg;
1144 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1146 * If cgroup removal path got to blk_group first and removed
1147 * it from cgroup list, then it will take care of destroying
1150 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1151 cfq_destroy_cfqg(cfqd, cfqg);
1156 * Blk cgroup controller notification saying that blkio_group object is being
1157 * delinked as associated cgroup object is going away. That also means that
1158 * no new IO will come in this group. So get rid of this group as soon as
1159 * any pending IO in the group is finished.
1161 * This function is called under rcu_read_lock(). key is the rcu protected
1162 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1165 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1166 * it should not be NULL as even if elevator was exiting, cgroup deltion
1167 * path got to it first.
1169 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1171 unsigned long flags;
1172 struct cfq_data *cfqd = key;
1174 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1175 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1176 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1179 #else /* GROUP_IOSCHED */
1180 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1182 return &cfqd->root_group;
1185 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1191 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1195 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1196 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1198 #endif /* GROUP_IOSCHED */
1201 * The cfqd->service_trees holds all pending cfq_queue's that have
1202 * requests waiting to be processed. It is sorted in the order that
1203 * we will service the queues.
1205 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1208 struct rb_node **p, *parent;
1209 struct cfq_queue *__cfqq;
1210 unsigned long rb_key;
1211 struct cfq_rb_root *service_tree;
1214 int group_changed = 0;
1216 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1218 if (cfq_class_idle(cfqq)) {
1219 rb_key = CFQ_IDLE_DELAY;
1220 parent = rb_last(&service_tree->rb);
1221 if (parent && parent != &cfqq->rb_node) {
1222 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1223 rb_key += __cfqq->rb_key;
1226 } else if (!add_front) {
1228 * Get our rb key offset. Subtract any residual slice
1229 * value carried from last service. A negative resid
1230 * count indicates slice overrun, and this should position
1231 * the next service time further away in the tree.
1233 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1234 rb_key -= cfqq->slice_resid;
1235 cfqq->slice_resid = 0;
1238 __cfqq = cfq_rb_first(service_tree);
1239 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1242 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1245 * same position, nothing more to do
1247 if (rb_key == cfqq->rb_key &&
1248 cfqq->service_tree == service_tree)
1251 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1252 cfqq->service_tree = NULL;
1257 cfqq->service_tree = service_tree;
1258 p = &service_tree->rb.rb_node;
1263 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1266 * sort by key, that represents service time.
1268 if (time_before(rb_key, __cfqq->rb_key))
1271 n = &(*p)->rb_right;
1279 service_tree->left = &cfqq->rb_node;
1281 cfqq->rb_key = rb_key;
1282 rb_link_node(&cfqq->rb_node, parent, p);
1283 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1284 service_tree->count++;
1285 if ((add_front || !new_cfqq) && !group_changed)
1287 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1290 static struct cfq_queue *
1291 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1292 sector_t sector, struct rb_node **ret_parent,
1293 struct rb_node ***rb_link)
1295 struct rb_node **p, *parent;
1296 struct cfq_queue *cfqq = NULL;
1304 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1307 * Sort strictly based on sector. Smallest to the left,
1308 * largest to the right.
1310 if (sector > blk_rq_pos(cfqq->next_rq))
1311 n = &(*p)->rb_right;
1312 else if (sector < blk_rq_pos(cfqq->next_rq))
1320 *ret_parent = parent;
1326 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1328 struct rb_node **p, *parent;
1329 struct cfq_queue *__cfqq;
1332 rb_erase(&cfqq->p_node, cfqq->p_root);
1333 cfqq->p_root = NULL;
1336 if (cfq_class_idle(cfqq))
1341 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1342 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1343 blk_rq_pos(cfqq->next_rq), &parent, &p);
1345 rb_link_node(&cfqq->p_node, parent, p);
1346 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1348 cfqq->p_root = NULL;
1352 * Update cfqq's position in the service tree.
1354 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1357 * Resorting requires the cfqq to be on the RR list already.
1359 if (cfq_cfqq_on_rr(cfqq)) {
1360 cfq_service_tree_add(cfqd, cfqq, 0);
1361 cfq_prio_tree_add(cfqd, cfqq);
1366 * add to busy list of queues for service, trying to be fair in ordering
1367 * the pending list according to last request service
1369 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1371 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1372 BUG_ON(cfq_cfqq_on_rr(cfqq));
1373 cfq_mark_cfqq_on_rr(cfqq);
1374 cfqd->busy_queues++;
1375 if (cfq_cfqq_sync(cfqq))
1376 cfqd->busy_sync_queues++;
1378 cfq_resort_rr_list(cfqd, cfqq);
1382 * Called when the cfqq no longer has requests pending, remove it from
1385 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1387 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1388 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1389 cfq_clear_cfqq_on_rr(cfqq);
1391 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1392 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1393 cfqq->service_tree = NULL;
1396 rb_erase(&cfqq->p_node, cfqq->p_root);
1397 cfqq->p_root = NULL;
1400 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1401 BUG_ON(!cfqd->busy_queues);
1402 cfqd->busy_queues--;
1403 if (cfq_cfqq_sync(cfqq))
1404 cfqd->busy_sync_queues--;
1408 * rb tree support functions
1410 static void cfq_del_rq_rb(struct request *rq)
1412 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1413 const int sync = rq_is_sync(rq);
1415 BUG_ON(!cfqq->queued[sync]);
1416 cfqq->queued[sync]--;
1418 elv_rb_del(&cfqq->sort_list, rq);
1420 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1422 * Queue will be deleted from service tree when we actually
1423 * expire it later. Right now just remove it from prio tree
1427 rb_erase(&cfqq->p_node, cfqq->p_root);
1428 cfqq->p_root = NULL;
1433 static void cfq_add_rq_rb(struct request *rq)
1435 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1436 struct cfq_data *cfqd = cfqq->cfqd;
1437 struct request *__alias, *prev;
1439 cfqq->queued[rq_is_sync(rq)]++;
1442 * looks a little odd, but the first insert might return an alias.
1443 * if that happens, put the alias on the dispatch list
1445 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1446 cfq_dispatch_insert(cfqd->queue, __alias);
1448 if (!cfq_cfqq_on_rr(cfqq))
1449 cfq_add_cfqq_rr(cfqd, cfqq);
1452 * check if this request is a better next-serve candidate
1454 prev = cfqq->next_rq;
1455 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1458 * adjust priority tree position, if ->next_rq changes
1460 if (prev != cfqq->next_rq)
1461 cfq_prio_tree_add(cfqd, cfqq);
1463 BUG_ON(!cfqq->next_rq);
1466 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1468 elv_rb_del(&cfqq->sort_list, rq);
1469 cfqq->queued[rq_is_sync(rq)]--;
1470 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1471 rq_data_dir(rq), rq_is_sync(rq));
1473 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1474 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1478 static struct request *
1479 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1481 struct task_struct *tsk = current;
1482 struct cfq_io_context *cic;
1483 struct cfq_queue *cfqq;
1485 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1489 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1491 sector_t sector = bio->bi_sector + bio_sectors(bio);
1493 return elv_rb_find(&cfqq->sort_list, sector);
1499 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1501 struct cfq_data *cfqd = q->elevator->elevator_data;
1503 cfqd->rq_in_driver++;
1504 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1505 cfqd->rq_in_driver);
1507 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1510 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1512 struct cfq_data *cfqd = q->elevator->elevator_data;
1514 WARN_ON(!cfqd->rq_in_driver);
1515 cfqd->rq_in_driver--;
1516 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1517 cfqd->rq_in_driver);
1520 static void cfq_remove_request(struct request *rq)
1522 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1524 if (cfqq->next_rq == rq)
1525 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1527 list_del_init(&rq->queuelist);
1530 cfqq->cfqd->rq_queued--;
1531 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1532 rq_data_dir(rq), rq_is_sync(rq));
1533 if (rq->cmd_flags & REQ_META) {
1534 WARN_ON(!cfqq->meta_pending);
1535 cfqq->meta_pending--;
1539 static int cfq_merge(struct request_queue *q, struct request **req,
1542 struct cfq_data *cfqd = q->elevator->elevator_data;
1543 struct request *__rq;
1545 __rq = cfq_find_rq_fmerge(cfqd, bio);
1546 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1548 return ELEVATOR_FRONT_MERGE;
1551 return ELEVATOR_NO_MERGE;
1554 static void cfq_merged_request(struct request_queue *q, struct request *req,
1557 if (type == ELEVATOR_FRONT_MERGE) {
1558 struct cfq_queue *cfqq = RQ_CFQQ(req);
1560 cfq_reposition_rq_rb(cfqq, req);
1564 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1567 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1568 bio_data_dir(bio), cfq_bio_sync(bio));
1572 cfq_merged_requests(struct request_queue *q, struct request *rq,
1573 struct request *next)
1575 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1577 * reposition in fifo if next is older than rq
1579 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1580 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1581 list_move(&rq->queuelist, &next->queuelist);
1582 rq_set_fifo_time(rq, rq_fifo_time(next));
1585 if (cfqq->next_rq == next)
1587 cfq_remove_request(next);
1588 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1589 rq_data_dir(next), rq_is_sync(next));
1592 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1595 struct cfq_data *cfqd = q->elevator->elevator_data;
1596 struct cfq_io_context *cic;
1597 struct cfq_queue *cfqq;
1600 * Disallow merge of a sync bio into an async request.
1602 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1606 * Lookup the cfqq that this bio will be queued with. Allow
1607 * merge only if rq is queued there.
1609 cic = cfq_cic_lookup(cfqd, current->io_context);
1613 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1614 return cfqq == RQ_CFQQ(rq);
1617 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1619 del_timer(&cfqd->idle_slice_timer);
1620 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1623 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1624 struct cfq_queue *cfqq)
1627 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1628 cfqd->serving_prio, cfqd->serving_type);
1629 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1630 cfqq->slice_start = 0;
1631 cfqq->dispatch_start = jiffies;
1632 cfqq->allocated_slice = 0;
1633 cfqq->slice_end = 0;
1634 cfqq->slice_dispatch = 0;
1635 cfqq->nr_sectors = 0;
1637 cfq_clear_cfqq_wait_request(cfqq);
1638 cfq_clear_cfqq_must_dispatch(cfqq);
1639 cfq_clear_cfqq_must_alloc_slice(cfqq);
1640 cfq_clear_cfqq_fifo_expire(cfqq);
1641 cfq_mark_cfqq_slice_new(cfqq);
1643 cfq_del_timer(cfqd, cfqq);
1646 cfqd->active_queue = cfqq;
1650 * current cfqq expired its slice (or was too idle), select new one
1653 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1656 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1658 if (cfq_cfqq_wait_request(cfqq))
1659 cfq_del_timer(cfqd, cfqq);
1661 cfq_clear_cfqq_wait_request(cfqq);
1662 cfq_clear_cfqq_wait_busy(cfqq);
1665 * If this cfqq is shared between multiple processes, check to
1666 * make sure that those processes are still issuing I/Os within
1667 * the mean seek distance. If not, it may be time to break the
1668 * queues apart again.
1670 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1671 cfq_mark_cfqq_split_coop(cfqq);
1674 * store what was left of this slice, if the queue idled/timed out
1677 if (cfq_cfqq_slice_new(cfqq))
1678 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1680 cfqq->slice_resid = cfqq->slice_end - jiffies;
1681 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1684 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1686 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1687 cfq_del_cfqq_rr(cfqd, cfqq);
1689 cfq_resort_rr_list(cfqd, cfqq);
1691 if (cfqq == cfqd->active_queue)
1692 cfqd->active_queue = NULL;
1694 if (cfqd->active_cic) {
1695 put_io_context(cfqd->active_cic->ioc);
1696 cfqd->active_cic = NULL;
1700 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1702 struct cfq_queue *cfqq = cfqd->active_queue;
1705 __cfq_slice_expired(cfqd, cfqq, timed_out);
1709 * Get next queue for service. Unless we have a queue preemption,
1710 * we'll simply select the first cfqq in the service tree.
1712 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1714 struct cfq_rb_root *service_tree =
1715 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1716 cfqd->serving_type);
1718 if (!cfqd->rq_queued)
1721 /* There is nothing to dispatch */
1724 if (RB_EMPTY_ROOT(&service_tree->rb))
1726 return cfq_rb_first(service_tree);
1729 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1731 struct cfq_group *cfqg;
1732 struct cfq_queue *cfqq;
1734 struct cfq_rb_root *st;
1736 if (!cfqd->rq_queued)
1739 cfqg = cfq_get_next_cfqg(cfqd);
1743 for_each_cfqg_st(cfqg, i, j, st)
1744 if ((cfqq = cfq_rb_first(st)) != NULL)
1750 * Get and set a new active queue for service.
1752 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1753 struct cfq_queue *cfqq)
1756 cfqq = cfq_get_next_queue(cfqd);
1758 __cfq_set_active_queue(cfqd, cfqq);
1762 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1765 if (blk_rq_pos(rq) >= cfqd->last_position)
1766 return blk_rq_pos(rq) - cfqd->last_position;
1768 return cfqd->last_position - blk_rq_pos(rq);
1771 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1774 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1777 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1778 struct cfq_queue *cur_cfqq)
1780 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1781 struct rb_node *parent, *node;
1782 struct cfq_queue *__cfqq;
1783 sector_t sector = cfqd->last_position;
1785 if (RB_EMPTY_ROOT(root))
1789 * First, if we find a request starting at the end of the last
1790 * request, choose it.
1792 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1797 * If the exact sector wasn't found, the parent of the NULL leaf
1798 * will contain the closest sector.
1800 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1801 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1804 if (blk_rq_pos(__cfqq->next_rq) < sector)
1805 node = rb_next(&__cfqq->p_node);
1807 node = rb_prev(&__cfqq->p_node);
1811 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1812 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1820 * cur_cfqq - passed in so that we don't decide that the current queue is
1821 * closely cooperating with itself.
1823 * So, basically we're assuming that that cur_cfqq has dispatched at least
1824 * one request, and that cfqd->last_position reflects a position on the disk
1825 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1828 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1829 struct cfq_queue *cur_cfqq)
1831 struct cfq_queue *cfqq;
1833 if (cfq_class_idle(cur_cfqq))
1835 if (!cfq_cfqq_sync(cur_cfqq))
1837 if (CFQQ_SEEKY(cur_cfqq))
1841 * Don't search priority tree if it's the only queue in the group.
1843 if (cur_cfqq->cfqg->nr_cfqq == 1)
1847 * We should notice if some of the queues are cooperating, eg
1848 * working closely on the same area of the disk. In that case,
1849 * we can group them together and don't waste time idling.
1851 cfqq = cfqq_close(cfqd, cur_cfqq);
1855 /* If new queue belongs to different cfq_group, don't choose it */
1856 if (cur_cfqq->cfqg != cfqq->cfqg)
1860 * It only makes sense to merge sync queues.
1862 if (!cfq_cfqq_sync(cfqq))
1864 if (CFQQ_SEEKY(cfqq))
1868 * Do not merge queues of different priority classes
1870 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1877 * Determine whether we should enforce idle window for this queue.
1880 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1882 enum wl_prio_t prio = cfqq_prio(cfqq);
1883 struct cfq_rb_root *service_tree = cfqq->service_tree;
1885 BUG_ON(!service_tree);
1886 BUG_ON(!service_tree->count);
1888 if (!cfqd->cfq_slice_idle)
1891 /* We never do for idle class queues. */
1892 if (prio == IDLE_WORKLOAD)
1895 /* We do for queues that were marked with idle window flag. */
1896 if (cfq_cfqq_idle_window(cfqq) &&
1897 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1901 * Otherwise, we do only if they are the last ones
1902 * in their service tree.
1904 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1906 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1907 service_tree->count);
1911 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1913 struct cfq_queue *cfqq = cfqd->active_queue;
1914 struct cfq_io_context *cic;
1915 unsigned long sl, group_idle = 0;
1918 * SSD device without seek penalty, disable idling. But only do so
1919 * for devices that support queuing, otherwise we still have a problem
1920 * with sync vs async workloads.
1922 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1925 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1926 WARN_ON(cfq_cfqq_slice_new(cfqq));
1929 * idle is disabled, either manually or by past process history
1931 if (!cfq_should_idle(cfqd, cfqq)) {
1932 /* no queue idling. Check for group idling */
1933 if (cfqd->cfq_group_idle)
1934 group_idle = cfqd->cfq_group_idle;
1940 * still active requests from this queue, don't idle
1942 if (cfqq->dispatched)
1946 * task has exited, don't wait
1948 cic = cfqd->active_cic;
1949 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1953 * If our average think time is larger than the remaining time
1954 * slice, then don't idle. This avoids overrunning the allotted
1957 if (sample_valid(cic->ttime_samples) &&
1958 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1959 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1964 /* There are other queues in the group, don't do group idle */
1965 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
1968 cfq_mark_cfqq_wait_request(cfqq);
1971 sl = cfqd->cfq_group_idle;
1973 sl = cfqd->cfq_slice_idle;
1975 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1976 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1977 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
1978 group_idle ? 1 : 0);
1982 * Move request from internal lists to the request queue dispatch list.
1984 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1986 struct cfq_data *cfqd = q->elevator->elevator_data;
1987 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1989 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1991 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1992 cfq_remove_request(rq);
1994 (RQ_CFQG(rq))->dispatched++;
1995 elv_dispatch_sort(q, rq);
1997 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1998 cfqq->nr_sectors += blk_rq_sectors(rq);
1999 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2000 rq_data_dir(rq), rq_is_sync(rq));
2004 * return expired entry, or NULL to just start from scratch in rbtree
2006 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2008 struct request *rq = NULL;
2010 if (cfq_cfqq_fifo_expire(cfqq))
2013 cfq_mark_cfqq_fifo_expire(cfqq);
2015 if (list_empty(&cfqq->fifo))
2018 rq = rq_entry_fifo(cfqq->fifo.next);
2019 if (time_before(jiffies, rq_fifo_time(rq)))
2022 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2027 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2029 const int base_rq = cfqd->cfq_slice_async_rq;
2031 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2033 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
2037 * Must be called with the queue_lock held.
2039 static int cfqq_process_refs(struct cfq_queue *cfqq)
2041 int process_refs, io_refs;
2043 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2044 process_refs = cfqq->ref - io_refs;
2045 BUG_ON(process_refs < 0);
2046 return process_refs;
2049 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2051 int process_refs, new_process_refs;
2052 struct cfq_queue *__cfqq;
2055 * If there are no process references on the new_cfqq, then it is
2056 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2057 * chain may have dropped their last reference (not just their
2058 * last process reference).
2060 if (!cfqq_process_refs(new_cfqq))
2063 /* Avoid a circular list and skip interim queue merges */
2064 while ((__cfqq = new_cfqq->new_cfqq)) {
2070 process_refs = cfqq_process_refs(cfqq);
2071 new_process_refs = cfqq_process_refs(new_cfqq);
2073 * If the process for the cfqq has gone away, there is no
2074 * sense in merging the queues.
2076 if (process_refs == 0 || new_process_refs == 0)
2080 * Merge in the direction of the lesser amount of work.
2082 if (new_process_refs >= process_refs) {
2083 cfqq->new_cfqq = new_cfqq;
2084 new_cfqq->ref += process_refs;
2086 new_cfqq->new_cfqq = cfqq;
2087 cfqq->ref += new_process_refs;
2091 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2092 struct cfq_group *cfqg, enum wl_prio_t prio)
2094 struct cfq_queue *queue;
2096 bool key_valid = false;
2097 unsigned long lowest_key = 0;
2098 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2100 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2101 /* select the one with lowest rb_key */
2102 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2104 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2105 lowest_key = queue->rb_key;
2114 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2118 struct cfq_rb_root *st;
2119 unsigned group_slice;
2120 enum wl_prio_t original_prio = cfqd->serving_prio;
2122 /* Choose next priority. RT > BE > IDLE */
2123 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2124 cfqd->serving_prio = RT_WORKLOAD;
2125 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2126 cfqd->serving_prio = BE_WORKLOAD;
2128 cfqd->serving_prio = IDLE_WORKLOAD;
2129 cfqd->workload_expires = jiffies + 1;
2133 if (original_prio != cfqd->serving_prio)
2137 * For RT and BE, we have to choose also the type
2138 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2141 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2145 * check workload expiration, and that we still have other queues ready
2147 if (count && !time_after(jiffies, cfqd->workload_expires))
2151 /* otherwise select new workload type */
2152 cfqd->serving_type =
2153 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2154 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2158 * the workload slice is computed as a fraction of target latency
2159 * proportional to the number of queues in that workload, over
2160 * all the queues in the same priority class
2162 group_slice = cfq_group_slice(cfqd, cfqg);
2164 slice = group_slice * count /
2165 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2166 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2168 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2172 * Async queues are currently system wide. Just taking
2173 * proportion of queues with-in same group will lead to higher
2174 * async ratio system wide as generally root group is going
2175 * to have higher weight. A more accurate thing would be to
2176 * calculate system wide asnc/sync ratio.
2178 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2179 tmp = tmp/cfqd->busy_queues;
2180 slice = min_t(unsigned, slice, tmp);
2182 /* async workload slice is scaled down according to
2183 * the sync/async slice ratio. */
2184 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2186 /* sync workload slice is at least 2 * cfq_slice_idle */
2187 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2189 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2190 cfq_log(cfqd, "workload slice:%d", slice);
2191 cfqd->workload_expires = jiffies + slice;
2194 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2196 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2197 struct cfq_group *cfqg;
2199 if (RB_EMPTY_ROOT(&st->rb))
2201 cfqg = cfq_rb_first_group(st);
2202 update_min_vdisktime(st);
2206 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2208 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2210 cfqd->serving_group = cfqg;
2212 /* Restore the workload type data */
2213 if (cfqg->saved_workload_slice) {
2214 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2215 cfqd->serving_type = cfqg->saved_workload;
2216 cfqd->serving_prio = cfqg->saved_serving_prio;
2218 cfqd->workload_expires = jiffies - 1;
2220 choose_service_tree(cfqd, cfqg);
2224 * Select a queue for service. If we have a current active queue,
2225 * check whether to continue servicing it, or retrieve and set a new one.
2227 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2229 struct cfq_queue *cfqq, *new_cfqq = NULL;
2231 cfqq = cfqd->active_queue;
2235 if (!cfqd->rq_queued)
2239 * We were waiting for group to get backlogged. Expire the queue
2241 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2245 * The active queue has run out of time, expire it and select new.
2247 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2249 * If slice had not expired at the completion of last request
2250 * we might not have turned on wait_busy flag. Don't expire
2251 * the queue yet. Allow the group to get backlogged.
2253 * The very fact that we have used the slice, that means we
2254 * have been idling all along on this queue and it should be
2255 * ok to wait for this request to complete.
2257 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2258 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2262 goto check_group_idle;
2266 * The active queue has requests and isn't expired, allow it to
2269 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2273 * If another queue has a request waiting within our mean seek
2274 * distance, let it run. The expire code will check for close
2275 * cooperators and put the close queue at the front of the service
2276 * tree. If possible, merge the expiring queue with the new cfqq.
2278 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2280 if (!cfqq->new_cfqq)
2281 cfq_setup_merge(cfqq, new_cfqq);
2286 * No requests pending. If the active queue still has requests in
2287 * flight or is idling for a new request, allow either of these
2288 * conditions to happen (or time out) before selecting a new queue.
2290 if (timer_pending(&cfqd->idle_slice_timer)) {
2296 * This is a deep seek queue, but the device is much faster than
2297 * the queue can deliver, don't idle
2299 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2300 (cfq_cfqq_slice_new(cfqq) ||
2301 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2302 cfq_clear_cfqq_deep(cfqq);
2303 cfq_clear_cfqq_idle_window(cfqq);
2306 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2312 * If group idle is enabled and there are requests dispatched from
2313 * this group, wait for requests to complete.
2316 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2317 && cfqq->cfqg->dispatched) {
2323 cfq_slice_expired(cfqd, 0);
2326 * Current queue expired. Check if we have to switch to a new
2330 cfq_choose_cfqg(cfqd);
2332 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2337 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2341 while (cfqq->next_rq) {
2342 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2346 BUG_ON(!list_empty(&cfqq->fifo));
2348 /* By default cfqq is not expired if it is empty. Do it explicitly */
2349 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2354 * Drain our current requests. Used for barriers and when switching
2355 * io schedulers on-the-fly.
2357 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2359 struct cfq_queue *cfqq;
2362 /* Expire the timeslice of the current active queue first */
2363 cfq_slice_expired(cfqd, 0);
2364 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2365 __cfq_set_active_queue(cfqd, cfqq);
2366 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2369 BUG_ON(cfqd->busy_queues);
2371 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2375 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2376 struct cfq_queue *cfqq)
2378 /* the queue hasn't finished any request, can't estimate */
2379 if (cfq_cfqq_slice_new(cfqq))
2381 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2388 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2390 unsigned int max_dispatch;
2393 * Drain async requests before we start sync IO
2395 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2399 * If this is an async queue and we have sync IO in flight, let it wait
2401 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2404 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2405 if (cfq_class_idle(cfqq))
2409 * Does this cfqq already have too much IO in flight?
2411 if (cfqq->dispatched >= max_dispatch) {
2412 bool promote_sync = false;
2414 * idle queue must always only have a single IO in flight
2416 if (cfq_class_idle(cfqq))
2420 * If there is only one sync queue, and its think time is
2421 * small, we can ignore async queue here and give the sync
2422 * queue no dispatch limit. The reason is a sync queue can
2423 * preempt async queue, limiting the sync queue doesn't make
2424 * sense. This is useful for aiostress test.
2426 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) {
2427 struct cfq_io_context *cic = RQ_CIC(cfqq->next_rq);
2429 if (sample_valid(cic->ttime_samples) &&
2430 cic->ttime_mean < cfqd->cfq_slice_idle)
2431 promote_sync = true;
2435 * We have other queues, don't allow more IO from this one
2437 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2442 * Sole queue user, no limit
2444 if (cfqd->busy_queues == 1 || promote_sync)
2448 * Normally we start throttling cfqq when cfq_quantum/2
2449 * requests have been dispatched. But we can drive
2450 * deeper queue depths at the beginning of slice
2451 * subjected to upper limit of cfq_quantum.
2453 max_dispatch = cfqd->cfq_quantum;
2457 * Async queues must wait a bit before being allowed dispatch.
2458 * We also ramp up the dispatch depth gradually for async IO,
2459 * based on the last sync IO we serviced
2461 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2462 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2465 depth = last_sync / cfqd->cfq_slice[1];
2466 if (!depth && !cfqq->dispatched)
2468 if (depth < max_dispatch)
2469 max_dispatch = depth;
2473 * If we're below the current max, allow a dispatch
2475 return cfqq->dispatched < max_dispatch;
2479 * Dispatch a request from cfqq, moving them to the request queue
2482 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2486 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2488 if (!cfq_may_dispatch(cfqd, cfqq))
2492 * follow expired path, else get first next available
2494 rq = cfq_check_fifo(cfqq);
2499 * insert request into driver dispatch list
2501 cfq_dispatch_insert(cfqd->queue, rq);
2503 if (!cfqd->active_cic) {
2504 struct cfq_io_context *cic = RQ_CIC(rq);
2506 atomic_long_inc(&cic->ioc->refcount);
2507 cfqd->active_cic = cic;
2514 * Find the cfqq that we need to service and move a request from that to the
2517 static int cfq_dispatch_requests(struct request_queue *q, int force)
2519 struct cfq_data *cfqd = q->elevator->elevator_data;
2520 struct cfq_queue *cfqq;
2522 if (!cfqd->busy_queues)
2525 if (unlikely(force))
2526 return cfq_forced_dispatch(cfqd);
2528 cfqq = cfq_select_queue(cfqd);
2533 * Dispatch a request from this cfqq, if it is allowed
2535 if (!cfq_dispatch_request(cfqd, cfqq))
2538 cfqq->slice_dispatch++;
2539 cfq_clear_cfqq_must_dispatch(cfqq);
2542 * expire an async queue immediately if it has used up its slice. idle
2543 * queue always expire after 1 dispatch round.
2545 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2546 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2547 cfq_class_idle(cfqq))) {
2548 cfqq->slice_end = jiffies + 1;
2549 cfq_slice_expired(cfqd, 0);
2552 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2557 * task holds one reference to the queue, dropped when task exits. each rq
2558 * in-flight on this queue also holds a reference, dropped when rq is freed.
2560 * Each cfq queue took a reference on the parent group. Drop it now.
2561 * queue lock must be held here.
2563 static void cfq_put_queue(struct cfq_queue *cfqq)
2565 struct cfq_data *cfqd = cfqq->cfqd;
2566 struct cfq_group *cfqg;
2568 BUG_ON(cfqq->ref <= 0);
2574 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2575 BUG_ON(rb_first(&cfqq->sort_list));
2576 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2579 if (unlikely(cfqd->active_queue == cfqq)) {
2580 __cfq_slice_expired(cfqd, cfqq, 0);
2581 cfq_schedule_dispatch(cfqd);
2584 BUG_ON(cfq_cfqq_on_rr(cfqq));
2585 kmem_cache_free(cfq_pool, cfqq);
2590 * Must always be called with the rcu_read_lock() held
2593 __call_for_each_cic(struct io_context *ioc,
2594 void (*func)(struct io_context *, struct cfq_io_context *))
2596 struct cfq_io_context *cic;
2597 struct hlist_node *n;
2599 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2604 * Call func for each cic attached to this ioc.
2607 call_for_each_cic(struct io_context *ioc,
2608 void (*func)(struct io_context *, struct cfq_io_context *))
2611 __call_for_each_cic(ioc, func);
2615 static void cfq_cic_free_rcu(struct rcu_head *head)
2617 struct cfq_io_context *cic;
2619 cic = container_of(head, struct cfq_io_context, rcu_head);
2621 kmem_cache_free(cfq_ioc_pool, cic);
2622 elv_ioc_count_dec(cfq_ioc_count);
2626 * CFQ scheduler is exiting, grab exit lock and check
2627 * the pending io context count. If it hits zero,
2628 * complete ioc_gone and set it back to NULL
2630 spin_lock(&ioc_gone_lock);
2631 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2635 spin_unlock(&ioc_gone_lock);
2639 static void cfq_cic_free(struct cfq_io_context *cic)
2641 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2644 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2646 unsigned long flags;
2647 unsigned long dead_key = (unsigned long) cic->key;
2649 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2651 spin_lock_irqsave(&ioc->lock, flags);
2652 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2653 hlist_del_rcu(&cic->cic_list);
2654 spin_unlock_irqrestore(&ioc->lock, flags);
2660 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2661 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2662 * and ->trim() which is called with the task lock held
2664 static void cfq_free_io_context(struct io_context *ioc)
2667 * ioc->refcount is zero here, or we are called from elv_unregister(),
2668 * so no more cic's are allowed to be linked into this ioc. So it
2669 * should be ok to iterate over the known list, we will see all cic's
2670 * since no new ones are added.
2672 __call_for_each_cic(ioc, cic_free_func);
2675 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2677 struct cfq_queue *__cfqq, *next;
2680 * If this queue was scheduled to merge with another queue, be
2681 * sure to drop the reference taken on that queue (and others in
2682 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2684 __cfqq = cfqq->new_cfqq;
2686 if (__cfqq == cfqq) {
2687 WARN(1, "cfqq->new_cfqq loop detected\n");
2690 next = __cfqq->new_cfqq;
2691 cfq_put_queue(__cfqq);
2696 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2698 if (unlikely(cfqq == cfqd->active_queue)) {
2699 __cfq_slice_expired(cfqd, cfqq, 0);
2700 cfq_schedule_dispatch(cfqd);
2703 cfq_put_cooperator(cfqq);
2705 cfq_put_queue(cfqq);
2708 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2709 struct cfq_io_context *cic)
2711 struct io_context *ioc = cic->ioc;
2713 list_del_init(&cic->queue_list);
2716 * Make sure dead mark is seen for dead queues
2719 cic->key = cfqd_dead_key(cfqd);
2721 if (ioc->ioc_data == cic)
2722 rcu_assign_pointer(ioc->ioc_data, NULL);
2724 if (cic->cfqq[BLK_RW_ASYNC]) {
2725 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2726 cic->cfqq[BLK_RW_ASYNC] = NULL;
2729 if (cic->cfqq[BLK_RW_SYNC]) {
2730 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2731 cic->cfqq[BLK_RW_SYNC] = NULL;
2735 static void cfq_exit_single_io_context(struct io_context *ioc,
2736 struct cfq_io_context *cic)
2738 struct cfq_data *cfqd = cic_to_cfqd(cic);
2741 struct request_queue *q = cfqd->queue;
2742 unsigned long flags;
2744 spin_lock_irqsave(q->queue_lock, flags);
2747 * Ensure we get a fresh copy of the ->key to prevent
2748 * race between exiting task and queue
2750 smp_read_barrier_depends();
2751 if (cic->key == cfqd)
2752 __cfq_exit_single_io_context(cfqd, cic);
2754 spin_unlock_irqrestore(q->queue_lock, flags);
2759 * The process that ioc belongs to has exited, we need to clean up
2760 * and put the internal structures we have that belongs to that process.
2762 static void cfq_exit_io_context(struct io_context *ioc)
2764 call_for_each_cic(ioc, cfq_exit_single_io_context);
2767 static struct cfq_io_context *
2768 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2770 struct cfq_io_context *cic;
2772 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2775 cic->last_end_request = jiffies;
2776 INIT_LIST_HEAD(&cic->queue_list);
2777 INIT_HLIST_NODE(&cic->cic_list);
2778 cic->dtor = cfq_free_io_context;
2779 cic->exit = cfq_exit_io_context;
2780 elv_ioc_count_inc(cfq_ioc_count);
2786 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2788 struct task_struct *tsk = current;
2791 if (!cfq_cfqq_prio_changed(cfqq))
2794 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2795 switch (ioprio_class) {
2797 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2798 case IOPRIO_CLASS_NONE:
2800 * no prio set, inherit CPU scheduling settings
2802 cfqq->ioprio = task_nice_ioprio(tsk);
2803 cfqq->ioprio_class = task_nice_ioclass(tsk);
2805 case IOPRIO_CLASS_RT:
2806 cfqq->ioprio = task_ioprio(ioc);
2807 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2809 case IOPRIO_CLASS_BE:
2810 cfqq->ioprio = task_ioprio(ioc);
2811 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2813 case IOPRIO_CLASS_IDLE:
2814 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2816 cfq_clear_cfqq_idle_window(cfqq);
2821 * keep track of original prio settings in case we have to temporarily
2822 * elevate the priority of this queue
2824 cfqq->org_ioprio = cfqq->ioprio;
2825 cfqq->org_ioprio_class = cfqq->ioprio_class;
2826 cfq_clear_cfqq_prio_changed(cfqq);
2829 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2831 struct cfq_data *cfqd = cic_to_cfqd(cic);
2832 struct cfq_queue *cfqq;
2833 unsigned long flags;
2835 if (unlikely(!cfqd))
2838 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2840 cfqq = cic->cfqq[BLK_RW_ASYNC];
2842 struct cfq_queue *new_cfqq;
2843 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2846 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2847 cfq_put_queue(cfqq);
2851 cfqq = cic->cfqq[BLK_RW_SYNC];
2853 cfq_mark_cfqq_prio_changed(cfqq);
2855 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2858 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2860 call_for_each_cic(ioc, changed_ioprio);
2861 ioc->ioprio_changed = 0;
2864 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2865 pid_t pid, bool is_sync)
2867 RB_CLEAR_NODE(&cfqq->rb_node);
2868 RB_CLEAR_NODE(&cfqq->p_node);
2869 INIT_LIST_HEAD(&cfqq->fifo);
2874 cfq_mark_cfqq_prio_changed(cfqq);
2877 if (!cfq_class_idle(cfqq))
2878 cfq_mark_cfqq_idle_window(cfqq);
2879 cfq_mark_cfqq_sync(cfqq);
2884 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2885 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2887 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2888 struct cfq_data *cfqd = cic_to_cfqd(cic);
2889 unsigned long flags;
2890 struct request_queue *q;
2892 if (unlikely(!cfqd))
2897 spin_lock_irqsave(q->queue_lock, flags);
2901 * Drop reference to sync queue. A new sync queue will be
2902 * assigned in new group upon arrival of a fresh request.
2904 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2905 cic_set_cfqq(cic, NULL, 1);
2906 cfq_put_queue(sync_cfqq);
2909 spin_unlock_irqrestore(q->queue_lock, flags);
2912 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2914 call_for_each_cic(ioc, changed_cgroup);
2915 ioc->cgroup_changed = 0;
2917 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2919 static struct cfq_queue *
2920 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2921 struct io_context *ioc, gfp_t gfp_mask)
2923 struct cfq_queue *cfqq, *new_cfqq = NULL;
2924 struct cfq_io_context *cic;
2925 struct cfq_group *cfqg;
2928 cfqg = cfq_get_cfqg(cfqd, 1);
2929 cic = cfq_cic_lookup(cfqd, ioc);
2930 /* cic always exists here */
2931 cfqq = cic_to_cfqq(cic, is_sync);
2934 * Always try a new alloc if we fell back to the OOM cfqq
2935 * originally, since it should just be a temporary situation.
2937 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2942 } else if (gfp_mask & __GFP_WAIT) {
2943 spin_unlock_irq(cfqd->queue->queue_lock);
2944 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2945 gfp_mask | __GFP_ZERO,
2947 spin_lock_irq(cfqd->queue->queue_lock);
2951 cfqq = kmem_cache_alloc_node(cfq_pool,
2952 gfp_mask | __GFP_ZERO,
2957 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2958 cfq_init_prio_data(cfqq, ioc);
2959 cfq_link_cfqq_cfqg(cfqq, cfqg);
2960 cfq_log_cfqq(cfqd, cfqq, "alloced");
2962 cfqq = &cfqd->oom_cfqq;
2966 kmem_cache_free(cfq_pool, new_cfqq);
2971 static struct cfq_queue **
2972 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2974 switch (ioprio_class) {
2975 case IOPRIO_CLASS_RT:
2976 return &cfqd->async_cfqq[0][ioprio];
2977 case IOPRIO_CLASS_BE:
2978 return &cfqd->async_cfqq[1][ioprio];
2979 case IOPRIO_CLASS_IDLE:
2980 return &cfqd->async_idle_cfqq;
2986 static struct cfq_queue *
2987 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2990 const int ioprio = task_ioprio(ioc);
2991 const int ioprio_class = task_ioprio_class(ioc);
2992 struct cfq_queue **async_cfqq = NULL;
2993 struct cfq_queue *cfqq = NULL;
2996 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3001 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
3004 * pin the queue now that it's allocated, scheduler exit will prune it
3006 if (!is_sync && !(*async_cfqq)) {
3016 * We drop cfq io contexts lazily, so we may find a dead one.
3019 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3020 struct cfq_io_context *cic)
3022 unsigned long flags;
3024 WARN_ON(!list_empty(&cic->queue_list));
3025 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3027 spin_lock_irqsave(&ioc->lock, flags);
3029 BUG_ON(ioc->ioc_data == cic);
3031 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3032 hlist_del_rcu(&cic->cic_list);
3033 spin_unlock_irqrestore(&ioc->lock, flags);
3038 static struct cfq_io_context *
3039 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3041 struct cfq_io_context *cic;
3042 unsigned long flags;
3050 * we maintain a last-hit cache, to avoid browsing over the tree
3052 cic = rcu_dereference(ioc->ioc_data);
3053 if (cic && cic->key == cfqd) {
3059 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3063 if (unlikely(cic->key != cfqd)) {
3064 cfq_drop_dead_cic(cfqd, ioc, cic);
3069 spin_lock_irqsave(&ioc->lock, flags);
3070 rcu_assign_pointer(ioc->ioc_data, cic);
3071 spin_unlock_irqrestore(&ioc->lock, flags);
3079 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3080 * the process specific cfq io context when entered from the block layer.
3081 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3083 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3084 struct cfq_io_context *cic, gfp_t gfp_mask)
3086 unsigned long flags;
3089 ret = radix_tree_preload(gfp_mask);
3094 spin_lock_irqsave(&ioc->lock, flags);
3095 ret = radix_tree_insert(&ioc->radix_root,
3096 cfqd->cic_index, cic);
3098 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3099 spin_unlock_irqrestore(&ioc->lock, flags);
3101 radix_tree_preload_end();
3104 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3105 list_add(&cic->queue_list, &cfqd->cic_list);
3106 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3111 printk(KERN_ERR "cfq: cic link failed!\n");
3117 * Setup general io context and cfq io context. There can be several cfq
3118 * io contexts per general io context, if this process is doing io to more
3119 * than one device managed by cfq.
3121 static struct cfq_io_context *
3122 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3124 struct io_context *ioc = NULL;
3125 struct cfq_io_context *cic;
3127 might_sleep_if(gfp_mask & __GFP_WAIT);
3129 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3133 cic = cfq_cic_lookup(cfqd, ioc);
3137 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3141 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3145 smp_read_barrier_depends();
3146 if (unlikely(ioc->ioprio_changed))
3147 cfq_ioc_set_ioprio(ioc);
3149 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3150 if (unlikely(ioc->cgroup_changed))
3151 cfq_ioc_set_cgroup(ioc);
3157 put_io_context(ioc);
3162 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3164 unsigned long elapsed = jiffies - cic->last_end_request;
3165 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3167 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3168 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3169 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3173 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3177 sector_t n_sec = blk_rq_sectors(rq);
3178 if (cfqq->last_request_pos) {
3179 if (cfqq->last_request_pos < blk_rq_pos(rq))
3180 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3182 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3185 cfqq->seek_history <<= 1;
3186 if (blk_queue_nonrot(cfqd->queue))
3187 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3189 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3193 * Disable idle window if the process thinks too long or seeks so much that
3197 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3198 struct cfq_io_context *cic)
3200 int old_idle, enable_idle;
3203 * Don't idle for async or idle io prio class
3205 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3208 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3210 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3211 cfq_mark_cfqq_deep(cfqq);
3213 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3215 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3216 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3218 else if (sample_valid(cic->ttime_samples)) {
3219 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3225 if (old_idle != enable_idle) {
3226 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3228 cfq_mark_cfqq_idle_window(cfqq);
3230 cfq_clear_cfqq_idle_window(cfqq);
3235 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3236 * no or if we aren't sure, a 1 will cause a preempt.
3239 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3242 struct cfq_queue *cfqq;
3244 cfqq = cfqd->active_queue;
3248 if (cfq_class_idle(new_cfqq))
3251 if (cfq_class_idle(cfqq))
3255 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3257 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3261 * if the new request is sync, but the currently running queue is
3262 * not, let the sync request have priority.
3264 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3267 if (new_cfqq->cfqg != cfqq->cfqg)
3270 if (cfq_slice_used(cfqq))
3273 /* Allow preemption only if we are idling on sync-noidle tree */
3274 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3275 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3276 new_cfqq->service_tree->count == 2 &&
3277 RB_EMPTY_ROOT(&cfqq->sort_list))
3281 * So both queues are sync. Let the new request get disk time if
3282 * it's a metadata request and the current queue is doing regular IO.
3284 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3288 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3290 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3293 /* An idle queue should not be idle now for some reason */
3294 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3297 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3301 * if this request is as-good as one we would expect from the
3302 * current cfqq, let it preempt
3304 if (cfq_rq_close(cfqd, cfqq, rq))
3311 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3312 * let it have half of its nominal slice.
3314 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3316 struct cfq_queue *old_cfqq = cfqd->active_queue;
3318 cfq_log_cfqq(cfqd, cfqq, "preempt");
3319 cfq_slice_expired(cfqd, 1);
3322 * workload type is changed, don't save slice, otherwise preempt
3325 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3326 cfqq->cfqg->saved_workload_slice = 0;
3329 * Put the new queue at the front of the of the current list,
3330 * so we know that it will be selected next.
3332 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3334 cfq_service_tree_add(cfqd, cfqq, 1);
3336 cfqq->slice_end = 0;
3337 cfq_mark_cfqq_slice_new(cfqq);
3341 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3342 * something we should do about it
3345 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3348 struct cfq_io_context *cic = RQ_CIC(rq);
3351 if (rq->cmd_flags & REQ_META)
3352 cfqq->meta_pending++;
3354 cfq_update_io_thinktime(cfqd, cic);
3355 cfq_update_io_seektime(cfqd, cfqq, rq);
3356 cfq_update_idle_window(cfqd, cfqq, cic);
3358 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3360 if (cfqq == cfqd->active_queue) {
3362 * Remember that we saw a request from this process, but
3363 * don't start queuing just yet. Otherwise we risk seeing lots
3364 * of tiny requests, because we disrupt the normal plugging
3365 * and merging. If the request is already larger than a single
3366 * page, let it rip immediately. For that case we assume that
3367 * merging is already done. Ditto for a busy system that
3368 * has other work pending, don't risk delaying until the
3369 * idle timer unplug to continue working.
3371 if (cfq_cfqq_wait_request(cfqq)) {
3372 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3373 cfqd->busy_queues > 1) {
3374 cfq_del_timer(cfqd, cfqq);
3375 cfq_clear_cfqq_wait_request(cfqq);
3376 __blk_run_queue(cfqd->queue, false);
3378 cfq_blkiocg_update_idle_time_stats(
3380 cfq_mark_cfqq_must_dispatch(cfqq);
3383 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3385 * not the active queue - expire current slice if it is
3386 * idle and has expired it's mean thinktime or this new queue
3387 * has some old slice time left and is of higher priority or
3388 * this new queue is RT and the current one is BE
3390 cfq_preempt_queue(cfqd, cfqq);
3391 __blk_run_queue(cfqd->queue, false);
3395 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3397 struct cfq_data *cfqd = q->elevator->elevator_data;
3398 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3400 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3401 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3403 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3404 list_add_tail(&rq->queuelist, &cfqq->fifo);
3406 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3407 &cfqd->serving_group->blkg, rq_data_dir(rq),
3409 cfq_rq_enqueued(cfqd, cfqq, rq);
3413 * Update hw_tag based on peak queue depth over 50 samples under
3416 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3418 struct cfq_queue *cfqq = cfqd->active_queue;
3420 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3421 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3423 if (cfqd->hw_tag == 1)
3426 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3427 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3431 * If active queue hasn't enough requests and can idle, cfq might not
3432 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3435 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3436 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3437 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3440 if (cfqd->hw_tag_samples++ < 50)
3443 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3449 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3451 struct cfq_io_context *cic = cfqd->active_cic;
3453 /* If the queue already has requests, don't wait */
3454 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3457 /* If there are other queues in the group, don't wait */
3458 if (cfqq->cfqg->nr_cfqq > 1)
3461 if (cfq_slice_used(cfqq))
3464 /* if slice left is less than think time, wait busy */
3465 if (cic && sample_valid(cic->ttime_samples)
3466 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3470 * If think times is less than a jiffy than ttime_mean=0 and above
3471 * will not be true. It might happen that slice has not expired yet
3472 * but will expire soon (4-5 ns) during select_queue(). To cover the
3473 * case where think time is less than a jiffy, mark the queue wait
3474 * busy if only 1 jiffy is left in the slice.
3476 if (cfqq->slice_end - jiffies == 1)
3482 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3484 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3485 struct cfq_data *cfqd = cfqq->cfqd;
3486 const int sync = rq_is_sync(rq);
3490 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3491 !!(rq->cmd_flags & REQ_NOIDLE));
3493 cfq_update_hw_tag(cfqd);
3495 WARN_ON(!cfqd->rq_in_driver);
3496 WARN_ON(!cfqq->dispatched);
3497 cfqd->rq_in_driver--;
3499 (RQ_CFQG(rq))->dispatched--;
3500 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3501 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3502 rq_data_dir(rq), rq_is_sync(rq));
3504 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3507 RQ_CIC(rq)->last_end_request = now;
3508 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3509 cfqd->last_delayed_sync = now;
3513 * If this is the active queue, check if it needs to be expired,
3514 * or if we want to idle in case it has no pending requests.
3516 if (cfqd->active_queue == cfqq) {
3517 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3519 if (cfq_cfqq_slice_new(cfqq)) {
3520 cfq_set_prio_slice(cfqd, cfqq);
3521 cfq_clear_cfqq_slice_new(cfqq);
3525 * Should we wait for next request to come in before we expire
3528 if (cfq_should_wait_busy(cfqd, cfqq)) {
3529 unsigned long extend_sl = cfqd->cfq_slice_idle;
3530 if (!cfqd->cfq_slice_idle)
3531 extend_sl = cfqd->cfq_group_idle;
3532 cfqq->slice_end = jiffies + extend_sl;
3533 cfq_mark_cfqq_wait_busy(cfqq);
3534 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3538 * Idling is not enabled on:
3540 * - idle-priority queues
3542 * - queues with still some requests queued
3543 * - when there is a close cooperator
3545 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3546 cfq_slice_expired(cfqd, 1);
3547 else if (sync && cfqq_empty &&
3548 !cfq_close_cooperator(cfqd, cfqq)) {
3549 cfq_arm_slice_timer(cfqd);
3553 if (!cfqd->rq_in_driver)
3554 cfq_schedule_dispatch(cfqd);
3558 * we temporarily boost lower priority queues if they are holding fs exclusive
3559 * resources. they are boosted to normal prio (CLASS_BE/4)
3561 static void cfq_prio_boost(struct cfq_queue *cfqq)
3563 if (has_fs_excl()) {
3565 * boost idle prio on transactions that would lock out other
3566 * users of the filesystem
3568 if (cfq_class_idle(cfqq))
3569 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3570 if (cfqq->ioprio > IOPRIO_NORM)
3571 cfqq->ioprio = IOPRIO_NORM;
3574 * unboost the queue (if needed)
3576 cfqq->ioprio_class = cfqq->org_ioprio_class;
3577 cfqq->ioprio = cfqq->org_ioprio;
3581 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3583 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3584 cfq_mark_cfqq_must_alloc_slice(cfqq);
3585 return ELV_MQUEUE_MUST;
3588 return ELV_MQUEUE_MAY;
3591 static int cfq_may_queue(struct request_queue *q, int rw)
3593 struct cfq_data *cfqd = q->elevator->elevator_data;
3594 struct task_struct *tsk = current;
3595 struct cfq_io_context *cic;
3596 struct cfq_queue *cfqq;
3599 * don't force setup of a queue from here, as a call to may_queue
3600 * does not necessarily imply that a request actually will be queued.
3601 * so just lookup a possibly existing queue, or return 'may queue'
3604 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3606 return ELV_MQUEUE_MAY;
3608 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3610 cfq_init_prio_data(cfqq, cic->ioc);
3611 cfq_prio_boost(cfqq);
3613 return __cfq_may_queue(cfqq);
3616 return ELV_MQUEUE_MAY;
3620 * queue lock held here
3622 static void cfq_put_request(struct request *rq)
3624 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3627 const int rw = rq_data_dir(rq);
3629 BUG_ON(!cfqq->allocated[rw]);
3630 cfqq->allocated[rw]--;
3632 put_io_context(RQ_CIC(rq)->ioc);
3634 rq->elevator_private[0] = NULL;
3635 rq->elevator_private[1] = NULL;
3637 /* Put down rq reference on cfqg */
3638 cfq_put_cfqg(RQ_CFQG(rq));
3639 rq->elevator_private[2] = NULL;
3641 cfq_put_queue(cfqq);
3645 static struct cfq_queue *
3646 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3647 struct cfq_queue *cfqq)
3649 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3650 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3651 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3652 cfq_put_queue(cfqq);
3653 return cic_to_cfqq(cic, 1);
3657 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3658 * was the last process referring to said cfqq.
3660 static struct cfq_queue *
3661 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3663 if (cfqq_process_refs(cfqq) == 1) {
3664 cfqq->pid = current->pid;
3665 cfq_clear_cfqq_coop(cfqq);
3666 cfq_clear_cfqq_split_coop(cfqq);
3670 cic_set_cfqq(cic, NULL, 1);
3672 cfq_put_cooperator(cfqq);
3674 cfq_put_queue(cfqq);
3678 * Allocate cfq data structures associated with this request.
3681 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3683 struct cfq_data *cfqd = q->elevator->elevator_data;
3684 struct cfq_io_context *cic;
3685 const int rw = rq_data_dir(rq);
3686 const bool is_sync = rq_is_sync(rq);
3687 struct cfq_queue *cfqq;
3688 unsigned long flags;
3690 might_sleep_if(gfp_mask & __GFP_WAIT);
3692 cic = cfq_get_io_context(cfqd, gfp_mask);
3694 spin_lock_irqsave(q->queue_lock, flags);
3700 cfqq = cic_to_cfqq(cic, is_sync);
3701 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3702 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3703 cic_set_cfqq(cic, cfqq, is_sync);
3706 * If the queue was seeky for too long, break it apart.
3708 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3709 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3710 cfqq = split_cfqq(cic, cfqq);
3716 * Check to see if this queue is scheduled to merge with
3717 * another, closely cooperating queue. The merging of
3718 * queues happens here as it must be done in process context.
3719 * The reference on new_cfqq was taken in merge_cfqqs.
3722 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3725 cfqq->allocated[rw]++;
3728 rq->elevator_private[0] = cic;
3729 rq->elevator_private[1] = cfqq;
3730 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3731 spin_unlock_irqrestore(q->queue_lock, flags);
3736 put_io_context(cic->ioc);
3738 cfq_schedule_dispatch(cfqd);
3739 spin_unlock_irqrestore(q->queue_lock, flags);
3740 cfq_log(cfqd, "set_request fail");
3744 static void cfq_kick_queue(struct work_struct *work)
3746 struct cfq_data *cfqd =
3747 container_of(work, struct cfq_data, unplug_work);
3748 struct request_queue *q = cfqd->queue;
3750 spin_lock_irq(q->queue_lock);
3751 __blk_run_queue(cfqd->queue, false);
3752 spin_unlock_irq(q->queue_lock);
3756 * Timer running if the active_queue is currently idling inside its time slice
3758 static void cfq_idle_slice_timer(unsigned long data)
3760 struct cfq_data *cfqd = (struct cfq_data *) data;
3761 struct cfq_queue *cfqq;
3762 unsigned long flags;
3765 cfq_log(cfqd, "idle timer fired");
3767 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3769 cfqq = cfqd->active_queue;
3774 * We saw a request before the queue expired, let it through
3776 if (cfq_cfqq_must_dispatch(cfqq))
3782 if (cfq_slice_used(cfqq))
3786 * only expire and reinvoke request handler, if there are
3787 * other queues with pending requests
3789 if (!cfqd->busy_queues)
3793 * not expired and it has a request pending, let it dispatch
3795 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3799 * Queue depth flag is reset only when the idle didn't succeed
3801 cfq_clear_cfqq_deep(cfqq);
3804 cfq_slice_expired(cfqd, timed_out);
3806 cfq_schedule_dispatch(cfqd);
3808 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3811 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3813 del_timer_sync(&cfqd->idle_slice_timer);
3814 cancel_work_sync(&cfqd->unplug_work);
3817 static void cfq_put_async_queues(struct cfq_data *cfqd)
3821 for (i = 0; i < IOPRIO_BE_NR; i++) {
3822 if (cfqd->async_cfqq[0][i])
3823 cfq_put_queue(cfqd->async_cfqq[0][i]);
3824 if (cfqd->async_cfqq[1][i])
3825 cfq_put_queue(cfqd->async_cfqq[1][i]);
3828 if (cfqd->async_idle_cfqq)
3829 cfq_put_queue(cfqd->async_idle_cfqq);
3832 static void cfq_cfqd_free(struct rcu_head *head)
3834 kfree(container_of(head, struct cfq_data, rcu));
3837 static void cfq_exit_queue(struct elevator_queue *e)
3839 struct cfq_data *cfqd = e->elevator_data;
3840 struct request_queue *q = cfqd->queue;
3842 cfq_shutdown_timer_wq(cfqd);
3844 spin_lock_irq(q->queue_lock);
3846 if (cfqd->active_queue)
3847 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3849 while (!list_empty(&cfqd->cic_list)) {
3850 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3851 struct cfq_io_context,
3854 __cfq_exit_single_io_context(cfqd, cic);
3857 cfq_put_async_queues(cfqd);
3858 cfq_release_cfq_groups(cfqd);
3859 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3861 spin_unlock_irq(q->queue_lock);
3863 cfq_shutdown_timer_wq(cfqd);
3865 spin_lock(&cic_index_lock);
3866 ida_remove(&cic_index_ida, cfqd->cic_index);
3867 spin_unlock(&cic_index_lock);
3869 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3870 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3873 static int cfq_alloc_cic_index(void)
3878 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3881 spin_lock(&cic_index_lock);
3882 error = ida_get_new(&cic_index_ida, &index);
3883 spin_unlock(&cic_index_lock);
3884 if (error && error != -EAGAIN)
3891 static void *cfq_init_queue(struct request_queue *q)
3893 struct cfq_data *cfqd;
3895 struct cfq_group *cfqg;
3896 struct cfq_rb_root *st;
3898 i = cfq_alloc_cic_index();
3902 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3907 * Don't need take queue_lock in the routine, since we are
3908 * initializing the ioscheduler, and nobody is using cfqd
3910 cfqd->cic_index = i;
3912 /* Init root service tree */
3913 cfqd->grp_service_tree = CFQ_RB_ROOT;
3915 /* Init root group */
3916 cfqg = &cfqd->root_group;
3917 for_each_cfqg_st(cfqg, i, j, st)
3919 RB_CLEAR_NODE(&cfqg->rb_node);
3921 /* Give preference to root group over other groups */
3922 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3924 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3926 * Take a reference to root group which we never drop. This is just
3927 * to make sure that cfq_put_cfqg() does not try to kfree root group
3931 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3936 * Not strictly needed (since RB_ROOT just clears the node and we
3937 * zeroed cfqd on alloc), but better be safe in case someone decides
3938 * to add magic to the rb code
3940 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3941 cfqd->prio_trees[i] = RB_ROOT;
3944 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3945 * Grab a permanent reference to it, so that the normal code flow
3946 * will not attempt to free it.
3948 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3949 cfqd->oom_cfqq.ref++;
3950 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3952 INIT_LIST_HEAD(&cfqd->cic_list);
3956 init_timer(&cfqd->idle_slice_timer);
3957 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3958 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3960 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3962 cfqd->cfq_quantum = cfq_quantum;
3963 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3964 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3965 cfqd->cfq_back_max = cfq_back_max;
3966 cfqd->cfq_back_penalty = cfq_back_penalty;
3967 cfqd->cfq_slice[0] = cfq_slice_async;
3968 cfqd->cfq_slice[1] = cfq_slice_sync;
3969 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3970 cfqd->cfq_slice_idle = cfq_slice_idle;
3971 cfqd->cfq_group_idle = cfq_group_idle;
3972 cfqd->cfq_latency = 1;
3975 * we optimistically start assuming sync ops weren't delayed in last
3976 * second, in order to have larger depth for async operations.
3978 cfqd->last_delayed_sync = jiffies - HZ;
3982 static void cfq_slab_kill(void)
3985 * Caller already ensured that pending RCU callbacks are completed,
3986 * so we should have no busy allocations at this point.
3989 kmem_cache_destroy(cfq_pool);
3991 kmem_cache_destroy(cfq_ioc_pool);
3994 static int __init cfq_slab_setup(void)
3996 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4000 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
4011 * sysfs parts below -->
4014 cfq_var_show(unsigned int var, char *page)
4016 return sprintf(page, "%d\n", var);
4020 cfq_var_store(unsigned int *var, const char *page, size_t count)
4022 char *p = (char *) page;
4024 *var = simple_strtoul(p, &p, 10);
4028 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4029 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4031 struct cfq_data *cfqd = e->elevator_data; \
4032 unsigned int __data = __VAR; \
4034 __data = jiffies_to_msecs(__data); \
4035 return cfq_var_show(__data, (page)); \
4037 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4038 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4039 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4040 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4041 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4042 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4043 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4044 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4045 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4046 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4047 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4048 #undef SHOW_FUNCTION
4050 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4051 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4053 struct cfq_data *cfqd = e->elevator_data; \
4054 unsigned int __data; \
4055 int ret = cfq_var_store(&__data, (page), count); \
4056 if (__data < (MIN)) \
4058 else if (__data > (MAX)) \
4061 *(__PTR) = msecs_to_jiffies(__data); \
4063 *(__PTR) = __data; \
4066 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4067 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4069 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4071 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4072 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4074 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4075 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4076 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4077 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4078 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4080 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4081 #undef STORE_FUNCTION
4083 #define CFQ_ATTR(name) \
4084 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4086 static struct elv_fs_entry cfq_attrs[] = {
4088 CFQ_ATTR(fifo_expire_sync),
4089 CFQ_ATTR(fifo_expire_async),
4090 CFQ_ATTR(back_seek_max),
4091 CFQ_ATTR(back_seek_penalty),
4092 CFQ_ATTR(slice_sync),
4093 CFQ_ATTR(slice_async),
4094 CFQ_ATTR(slice_async_rq),
4095 CFQ_ATTR(slice_idle),
4096 CFQ_ATTR(group_idle),
4097 CFQ_ATTR(low_latency),
4101 static struct elevator_type iosched_cfq = {
4103 .elevator_merge_fn = cfq_merge,
4104 .elevator_merged_fn = cfq_merged_request,
4105 .elevator_merge_req_fn = cfq_merged_requests,
4106 .elevator_allow_merge_fn = cfq_allow_merge,
4107 .elevator_bio_merged_fn = cfq_bio_merged,
4108 .elevator_dispatch_fn = cfq_dispatch_requests,
4109 .elevator_add_req_fn = cfq_insert_request,
4110 .elevator_activate_req_fn = cfq_activate_request,
4111 .elevator_deactivate_req_fn = cfq_deactivate_request,
4112 .elevator_completed_req_fn = cfq_completed_request,
4113 .elevator_former_req_fn = elv_rb_former_request,
4114 .elevator_latter_req_fn = elv_rb_latter_request,
4115 .elevator_set_req_fn = cfq_set_request,
4116 .elevator_put_req_fn = cfq_put_request,
4117 .elevator_may_queue_fn = cfq_may_queue,
4118 .elevator_init_fn = cfq_init_queue,
4119 .elevator_exit_fn = cfq_exit_queue,
4120 .trim = cfq_free_io_context,
4122 .elevator_attrs = cfq_attrs,
4123 .elevator_name = "cfq",
4124 .elevator_owner = THIS_MODULE,
4127 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4128 static struct blkio_policy_type blkio_policy_cfq = {
4130 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4131 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4133 .plid = BLKIO_POLICY_PROP,
4136 static struct blkio_policy_type blkio_policy_cfq;
4139 static int __init cfq_init(void)
4142 * could be 0 on HZ < 1000 setups
4144 if (!cfq_slice_async)
4145 cfq_slice_async = 1;
4146 if (!cfq_slice_idle)
4149 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4150 if (!cfq_group_idle)
4155 if (cfq_slab_setup())
4158 elv_register(&iosched_cfq);
4159 blkio_policy_register(&blkio_policy_cfq);
4164 static void __exit cfq_exit(void)
4166 DECLARE_COMPLETION_ONSTACK(all_gone);
4167 blkio_policy_unregister(&blkio_policy_cfq);
4168 elv_unregister(&iosched_cfq);
4169 ioc_gone = &all_gone;
4170 /* ioc_gone's update must be visible before reading ioc_count */
4174 * this also protects us from entering cfq_slab_kill() with
4175 * pending RCU callbacks
4177 if (elv_ioc_count_read(cfq_ioc_count))
4178 wait_for_completion(&all_gone);
4179 ida_destroy(&cic_index_ida);
4183 module_init(cfq_init);
4184 module_exit(cfq_exit);
4186 MODULE_AUTHOR("Jens Axboe");
4187 MODULE_LICENSE("GPL");
4188 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");