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;
90 struct cfq_ttime ttime;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
96 * Per process-grouping structure
101 /* various state flags, see below */
103 /* parent cfq_data */
104 struct cfq_data *cfqd;
105 /* service_tree member */
106 struct rb_node rb_node;
107 /* service_tree key */
108 unsigned long rb_key;
109 /* prio tree member */
110 struct rb_node p_node;
111 /* prio tree root we belong to, if any */
112 struct rb_root *p_root;
113 /* sorted list of pending requests */
114 struct rb_root sort_list;
115 /* if fifo isn't expired, next request to serve */
116 struct request *next_rq;
117 /* requests queued in sort_list */
119 /* currently allocated requests */
121 /* fifo list of requests in sort_list */
122 struct list_head fifo;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start;
126 unsigned int allocated_slice;
127 unsigned int slice_dispatch;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start;
130 unsigned long slice_end;
133 /* number of requests that are on the dispatch list or inside driver */
136 /* io prio of this group */
137 unsigned short ioprio, org_ioprio;
138 unsigned short ioprio_class;
143 sector_t last_request_pos;
145 struct cfq_rb_root *service_tree;
146 struct cfq_queue *new_cfqq;
147 struct cfq_group *cfqg;
148 /* Number of sectors dispatched from queue in single dispatch round */
149 unsigned long nr_sectors;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
164 * Second index in the service_trees.
168 SYNC_NOIDLE_WORKLOAD = 1,
172 /* This is per cgroup per device grouping structure */
174 /* group service_tree member */
175 struct rb_node rb_node;
177 /* group service_tree key */
180 unsigned int new_weight;
183 /* number of cfqq currently on this group */
187 * Per group busy queues average. Useful for workload slice calc. We
188 * create the array for each prio class but at run time it is used
189 * only for RT and BE class and slot for IDLE class remains unused.
190 * This is primarily done to avoid confusion and a gcc warning.
192 unsigned int busy_queues_avg[CFQ_PRIO_NR];
194 * rr lists of queues with requests. We maintain service trees for
195 * RT and BE classes. These trees are subdivided in subclasses
196 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
197 * class there is no subclassification and all the cfq queues go on
198 * a single tree service_tree_idle.
199 * Counts are embedded in the cfq_rb_root
201 struct cfq_rb_root service_trees[2][3];
202 struct cfq_rb_root service_tree_idle;
204 unsigned long saved_workload_slice;
205 enum wl_type_t saved_workload;
206 enum wl_prio_t saved_serving_prio;
207 struct blkio_group blkg;
208 #ifdef CONFIG_CFQ_GROUP_IOSCHED
209 struct hlist_node cfqd_node;
212 /* number of requests that are on the dispatch list or inside driver */
217 * Per block device queue structure
220 struct request_queue *queue;
221 /* Root service tree for cfq_groups */
222 struct cfq_rb_root grp_service_tree;
223 struct cfq_group root_group;
226 * The priority currently being served
228 enum wl_prio_t serving_prio;
229 enum wl_type_t serving_type;
230 unsigned long workload_expires;
231 struct cfq_group *serving_group;
234 * Each priority tree is sorted by next_request position. These
235 * trees are used when determining if two or more queues are
236 * interleaving requests (see cfq_close_cooperator).
238 struct rb_root prio_trees[CFQ_PRIO_LISTS];
240 unsigned int busy_queues;
241 unsigned int busy_sync_queues;
247 * queue-depth detection
253 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
254 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
257 int hw_tag_est_depth;
258 unsigned int hw_tag_samples;
261 * idle window management
263 struct timer_list idle_slice_timer;
264 struct work_struct unplug_work;
266 struct cfq_queue *active_queue;
267 struct cfq_io_context *active_cic;
270 * async queue for each priority case
272 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
273 struct cfq_queue *async_idle_cfqq;
275 sector_t last_position;
278 * tunables, see top of file
280 unsigned int cfq_quantum;
281 unsigned int cfq_fifo_expire[2];
282 unsigned int cfq_back_penalty;
283 unsigned int cfq_back_max;
284 unsigned int cfq_slice[2];
285 unsigned int cfq_slice_async_rq;
286 unsigned int cfq_slice_idle;
287 unsigned int cfq_group_idle;
288 unsigned int cfq_latency;
290 unsigned int cic_index;
291 struct list_head cic_list;
294 * Fallback dummy cfqq for extreme OOM conditions
296 struct cfq_queue oom_cfqq;
298 unsigned long last_delayed_sync;
300 /* List of cfq groups being managed on this device*/
301 struct hlist_head cfqg_list;
303 /* Number of groups which are on blkcg->blkg_list */
304 unsigned int nr_blkcg_linked_grps;
307 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
309 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
316 if (prio == IDLE_WORKLOAD)
317 return &cfqg->service_tree_idle;
319 return &cfqg->service_trees[prio][type];
322 enum cfqq_state_flags {
323 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
324 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
325 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
326 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
327 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
328 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
329 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
330 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
331 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
332 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
333 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
334 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
335 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
338 #define CFQ_CFQQ_FNS(name) \
339 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
343 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
345 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
347 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
349 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
353 CFQ_CFQQ_FNS(wait_request);
354 CFQ_CFQQ_FNS(must_dispatch);
355 CFQ_CFQQ_FNS(must_alloc_slice);
356 CFQ_CFQQ_FNS(fifo_expire);
357 CFQ_CFQQ_FNS(idle_window);
358 CFQ_CFQQ_FNS(prio_changed);
359 CFQ_CFQQ_FNS(slice_new);
362 CFQ_CFQQ_FNS(split_coop);
364 CFQ_CFQQ_FNS(wait_busy);
367 #ifdef CONFIG_CFQ_GROUP_IOSCHED
368 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
369 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
370 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
371 blkg_path(&(cfqq)->cfqg->blkg), ##args)
373 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
374 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
375 blkg_path(&(cfqg)->blkg), ##args) \
378 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
380 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
382 #define cfq_log(cfqd, fmt, args...) \
383 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
385 /* Traverses through cfq group service trees */
386 #define for_each_cfqg_st(cfqg, i, j, st) \
387 for (i = 0; i <= IDLE_WORKLOAD; i++) \
388 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
389 : &cfqg->service_tree_idle; \
390 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
391 (i == IDLE_WORKLOAD && j == 0); \
392 j++, st = i < IDLE_WORKLOAD ? \
393 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
396 struct cfq_ttime *ttime, bool group_idle)
399 if (!sample_valid(ttime->ttime_samples))
402 slice = cfqd->cfq_group_idle;
404 slice = cfqd->cfq_slice_idle;
405 return ttime->ttime_mean > slice;
408 static inline bool iops_mode(struct cfq_data *cfqd)
411 * If we are not idling on queues and it is a NCQ drive, parallel
412 * execution of requests is on and measuring time is not possible
413 * in most of the cases until and unless we drive shallower queue
414 * depths and that becomes a performance bottleneck. In such cases
415 * switch to start providing fairness in terms of number of IOs.
417 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
423 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
425 if (cfq_class_idle(cfqq))
426 return IDLE_WORKLOAD;
427 if (cfq_class_rt(cfqq))
433 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
435 if (!cfq_cfqq_sync(cfqq))
436 return ASYNC_WORKLOAD;
437 if (!cfq_cfqq_idle_window(cfqq))
438 return SYNC_NOIDLE_WORKLOAD;
439 return SYNC_WORKLOAD;
442 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
443 struct cfq_data *cfqd,
444 struct cfq_group *cfqg)
446 if (wl == IDLE_WORKLOAD)
447 return cfqg->service_tree_idle.count;
449 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
450 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
451 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
454 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
455 struct cfq_group *cfqg)
457 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
458 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
461 static void cfq_dispatch_insert(struct request_queue *, struct request *);
462 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
463 struct io_context *, gfp_t);
464 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
465 struct io_context *);
467 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
470 return cic->cfqq[is_sync];
473 static inline void cic_set_cfqq(struct cfq_io_context *cic,
474 struct cfq_queue *cfqq, bool is_sync)
476 cic->cfqq[is_sync] = cfqq;
479 #define CIC_DEAD_KEY 1ul
480 #define CIC_DEAD_INDEX_SHIFT 1
482 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
484 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
487 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
489 struct cfq_data *cfqd = cic->key;
491 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
498 * We regard a request as SYNC, if it's either a read or has the SYNC bit
499 * set (in which case it could also be direct WRITE).
501 static inline bool cfq_bio_sync(struct bio *bio)
503 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
507 * scheduler run of queue, if there are requests pending and no one in the
508 * driver that will restart queueing
510 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
512 if (cfqd->busy_queues) {
513 cfq_log(cfqd, "schedule dispatch");
514 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
519 * Scale schedule slice based on io priority. Use the sync time slice only
520 * if a queue is marked sync and has sync io queued. A sync queue with async
521 * io only, should not get full sync slice length.
523 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
526 const int base_slice = cfqd->cfq_slice[sync];
528 WARN_ON(prio >= IOPRIO_BE_NR);
530 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
534 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
536 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
539 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
541 u64 d = delta << CFQ_SERVICE_SHIFT;
543 d = d * BLKIO_WEIGHT_DEFAULT;
544 do_div(d, cfqg->weight);
548 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
550 s64 delta = (s64)(vdisktime - min_vdisktime);
552 min_vdisktime = vdisktime;
554 return min_vdisktime;
557 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
559 s64 delta = (s64)(vdisktime - min_vdisktime);
561 min_vdisktime = vdisktime;
563 return min_vdisktime;
566 static void update_min_vdisktime(struct cfq_rb_root *st)
568 struct cfq_group *cfqg;
571 cfqg = rb_entry_cfqg(st->left);
572 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
578 * get averaged number of queues of RT/BE priority.
579 * average is updated, with a formula that gives more weight to higher numbers,
580 * to quickly follows sudden increases and decrease slowly
583 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
584 struct cfq_group *cfqg, bool rt)
586 unsigned min_q, max_q;
587 unsigned mult = cfq_hist_divisor - 1;
588 unsigned round = cfq_hist_divisor / 2;
589 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
591 min_q = min(cfqg->busy_queues_avg[rt], busy);
592 max_q = max(cfqg->busy_queues_avg[rt], busy);
593 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
595 return cfqg->busy_queues_avg[rt];
598 static inline unsigned
599 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
601 struct cfq_rb_root *st = &cfqd->grp_service_tree;
603 return cfq_target_latency * cfqg->weight / st->total_weight;
606 static inline unsigned
607 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
609 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
610 if (cfqd->cfq_latency) {
612 * interested queues (we consider only the ones with the same
613 * priority class in the cfq group)
615 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
617 unsigned sync_slice = cfqd->cfq_slice[1];
618 unsigned expect_latency = sync_slice * iq;
619 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
621 if (expect_latency > group_slice) {
622 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
623 /* scale low_slice according to IO priority
624 * and sync vs async */
626 min(slice, base_low_slice * slice / sync_slice);
627 /* the adapted slice value is scaled to fit all iqs
628 * into the target latency */
629 slice = max(slice * group_slice / expect_latency,
637 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
639 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
641 cfqq->slice_start = jiffies;
642 cfqq->slice_end = jiffies + slice;
643 cfqq->allocated_slice = slice;
644 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
648 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
649 * isn't valid until the first request from the dispatch is activated
650 * and the slice time set.
652 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
654 if (cfq_cfqq_slice_new(cfqq))
656 if (time_before(jiffies, cfqq->slice_end))
663 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
664 * We choose the request that is closest to the head right now. Distance
665 * behind the head is penalized and only allowed to a certain extent.
667 static struct request *
668 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
670 sector_t s1, s2, d1 = 0, d2 = 0;
671 unsigned long back_max;
672 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
673 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
674 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
676 if (rq1 == NULL || rq1 == rq2)
681 if (rq_is_sync(rq1) != rq_is_sync(rq2))
682 return rq_is_sync(rq1) ? rq1 : rq2;
684 s1 = blk_rq_pos(rq1);
685 s2 = blk_rq_pos(rq2);
688 * by definition, 1KiB is 2 sectors
690 back_max = cfqd->cfq_back_max * 2;
693 * Strict one way elevator _except_ in the case where we allow
694 * short backward seeks which are biased as twice the cost of a
695 * similar forward seek.
699 else if (s1 + back_max >= last)
700 d1 = (last - s1) * cfqd->cfq_back_penalty;
702 wrap |= CFQ_RQ1_WRAP;
706 else if (s2 + back_max >= last)
707 d2 = (last - s2) * cfqd->cfq_back_penalty;
709 wrap |= CFQ_RQ2_WRAP;
711 /* Found required data */
714 * By doing switch() on the bit mask "wrap" we avoid having to
715 * check two variables for all permutations: --> faster!
718 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
734 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
737 * Since both rqs are wrapped,
738 * start with the one that's further behind head
739 * (--> only *one* back seek required),
740 * since back seek takes more time than forward.
750 * The below is leftmost cache rbtree addon
752 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
754 /* Service tree is empty */
759 root->left = rb_first(&root->rb);
762 return rb_entry(root->left, struct cfq_queue, rb_node);
767 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
770 root->left = rb_first(&root->rb);
773 return rb_entry_cfqg(root->left);
778 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
784 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
788 rb_erase_init(n, &root->rb);
793 * would be nice to take fifo expire time into account as well
795 static struct request *
796 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
797 struct request *last)
799 struct rb_node *rbnext = rb_next(&last->rb_node);
800 struct rb_node *rbprev = rb_prev(&last->rb_node);
801 struct request *next = NULL, *prev = NULL;
803 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
806 prev = rb_entry_rq(rbprev);
809 next = rb_entry_rq(rbnext);
811 rbnext = rb_first(&cfqq->sort_list);
812 if (rbnext && rbnext != &last->rb_node)
813 next = rb_entry_rq(rbnext);
816 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
819 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
820 struct cfq_queue *cfqq)
823 * just an approximation, should be ok.
825 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
826 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
830 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
832 return cfqg->vdisktime - st->min_vdisktime;
836 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
838 struct rb_node **node = &st->rb.rb_node;
839 struct rb_node *parent = NULL;
840 struct cfq_group *__cfqg;
841 s64 key = cfqg_key(st, cfqg);
844 while (*node != NULL) {
846 __cfqg = rb_entry_cfqg(parent);
848 if (key < cfqg_key(st, __cfqg))
849 node = &parent->rb_left;
851 node = &parent->rb_right;
857 st->left = &cfqg->rb_node;
859 rb_link_node(&cfqg->rb_node, parent, node);
860 rb_insert_color(&cfqg->rb_node, &st->rb);
864 cfq_update_group_weight(struct cfq_group *cfqg)
866 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
867 if (cfqg->needs_update) {
868 cfqg->weight = cfqg->new_weight;
869 cfqg->needs_update = false;
874 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
876 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
878 cfq_update_group_weight(cfqg);
879 __cfq_group_service_tree_add(st, cfqg);
880 st->total_weight += cfqg->weight;
884 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
886 struct cfq_rb_root *st = &cfqd->grp_service_tree;
887 struct cfq_group *__cfqg;
891 if (!RB_EMPTY_NODE(&cfqg->rb_node))
895 * Currently put the group at the end. Later implement something
896 * so that groups get lesser vtime based on their weights, so that
897 * if group does not loose all if it was not continuously backlogged.
899 n = rb_last(&st->rb);
901 __cfqg = rb_entry_cfqg(n);
902 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
904 cfqg->vdisktime = st->min_vdisktime;
905 cfq_group_service_tree_add(st, cfqg);
909 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
911 st->total_weight -= cfqg->weight;
912 if (!RB_EMPTY_NODE(&cfqg->rb_node))
913 cfq_rb_erase(&cfqg->rb_node, st);
917 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
919 struct cfq_rb_root *st = &cfqd->grp_service_tree;
921 BUG_ON(cfqg->nr_cfqq < 1);
924 /* If there are other cfq queues under this group, don't delete it */
928 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
929 cfq_group_service_tree_del(st, cfqg);
930 cfqg->saved_workload_slice = 0;
931 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
934 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
935 unsigned int *unaccounted_time)
937 unsigned int slice_used;
940 * Queue got expired before even a single request completed or
941 * got expired immediately after first request completion.
943 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
945 * Also charge the seek time incurred to the group, otherwise
946 * if there are mutiple queues in the group, each can dispatch
947 * a single request on seeky media and cause lots of seek time
948 * and group will never know it.
950 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
953 slice_used = jiffies - cfqq->slice_start;
954 if (slice_used > cfqq->allocated_slice) {
955 *unaccounted_time = slice_used - cfqq->allocated_slice;
956 slice_used = cfqq->allocated_slice;
958 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
959 *unaccounted_time += cfqq->slice_start -
960 cfqq->dispatch_start;
966 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
967 struct cfq_queue *cfqq)
969 struct cfq_rb_root *st = &cfqd->grp_service_tree;
970 unsigned int used_sl, charge, unaccounted_sl = 0;
971 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
972 - cfqg->service_tree_idle.count;
975 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
978 charge = cfqq->slice_dispatch;
979 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
980 charge = cfqq->allocated_slice;
982 /* Can't update vdisktime while group is on service tree */
983 cfq_group_service_tree_del(st, cfqg);
984 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
985 /* If a new weight was requested, update now, off tree */
986 cfq_group_service_tree_add(st, cfqg);
988 /* This group is being expired. Save the context */
989 if (time_after(cfqd->workload_expires, jiffies)) {
990 cfqg->saved_workload_slice = cfqd->workload_expires
992 cfqg->saved_workload = cfqd->serving_type;
993 cfqg->saved_serving_prio = cfqd->serving_prio;
995 cfqg->saved_workload_slice = 0;
997 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
999 cfq_log_cfqq(cfqq->cfqd, cfqq,
1000 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1001 used_sl, cfqq->slice_dispatch, charge,
1002 iops_mode(cfqd), cfqq->nr_sectors);
1003 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
1005 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
1008 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1009 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
1012 return container_of(blkg, struct cfq_group, blkg);
1016 static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1017 unsigned int weight)
1019 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1020 cfqg->new_weight = weight;
1021 cfqg->needs_update = true;
1024 static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
1025 struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
1027 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1028 unsigned int major, minor;
1031 * Add group onto cgroup list. It might happen that bdi->dev is
1032 * not initialized yet. Initialize this new group without major
1033 * and minor info and this info will be filled in once a new thread
1037 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1038 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1039 (void *)cfqd, MKDEV(major, minor));
1041 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1044 cfqd->nr_blkcg_linked_grps++;
1045 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1047 /* Add group on cfqd list */
1048 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1052 * Should be called from sleepable context. No request queue lock as per
1053 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1054 * from sleepable context.
1056 static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
1058 struct cfq_group *cfqg = NULL;
1060 struct cfq_rb_root *st;
1062 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1066 for_each_cfqg_st(cfqg, i, j, st)
1068 RB_CLEAR_NODE(&cfqg->rb_node);
1071 * Take the initial reference that will be released on destroy
1072 * This can be thought of a joint reference by cgroup and
1073 * elevator which will be dropped by either elevator exit
1074 * or cgroup deletion path depending on who is exiting first.
1078 ret = blkio_alloc_blkg_stats(&cfqg->blkg);
1087 static struct cfq_group *
1088 cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
1090 struct cfq_group *cfqg = NULL;
1092 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1093 unsigned int major, minor;
1096 * This is the common case when there are no blkio cgroups.
1097 * Avoid lookup in this case
1099 if (blkcg == &blkio_root_cgroup)
1100 cfqg = &cfqd->root_group;
1102 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1104 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1105 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1106 cfqg->blkg.dev = MKDEV(major, minor);
1113 * Search for the cfq group current task belongs to. request_queue lock must
1116 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1118 struct blkio_cgroup *blkcg;
1119 struct cfq_group *cfqg = NULL, *__cfqg = NULL;
1120 struct request_queue *q = cfqd->queue;
1123 blkcg = task_blkio_cgroup(current);
1124 cfqg = cfq_find_cfqg(cfqd, blkcg);
1131 * Need to allocate a group. Allocation of group also needs allocation
1132 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1133 * we need to drop rcu lock and queue_lock before we call alloc.
1135 * Not taking any queue reference here and assuming that queue is
1136 * around by the time we return. CFQ queue allocation code does
1137 * the same. It might be racy though.
1141 spin_unlock_irq(q->queue_lock);
1143 cfqg = cfq_alloc_cfqg(cfqd);
1145 spin_lock_irq(q->queue_lock);
1148 blkcg = task_blkio_cgroup(current);
1151 * If some other thread already allocated the group while we were
1152 * not holding queue lock, free up the group
1154 __cfqg = cfq_find_cfqg(cfqd, blkcg);
1163 cfqg = &cfqd->root_group;
1165 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
1170 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1176 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1178 /* Currently, all async queues are mapped to root group */
1179 if (!cfq_cfqq_sync(cfqq))
1180 cfqg = &cfqq->cfqd->root_group;
1183 /* cfqq reference on cfqg */
1187 static void cfq_put_cfqg(struct cfq_group *cfqg)
1189 struct cfq_rb_root *st;
1192 BUG_ON(cfqg->ref <= 0);
1196 for_each_cfqg_st(cfqg, i, j, st)
1197 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1198 free_percpu(cfqg->blkg.stats_cpu);
1202 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1204 /* Something wrong if we are trying to remove same group twice */
1205 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1207 hlist_del_init(&cfqg->cfqd_node);
1210 * Put the reference taken at the time of creation so that when all
1211 * queues are gone, group can be destroyed.
1216 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1218 struct hlist_node *pos, *n;
1219 struct cfq_group *cfqg;
1221 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1223 * If cgroup removal path got to blk_group first and removed
1224 * it from cgroup list, then it will take care of destroying
1227 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1228 cfq_destroy_cfqg(cfqd, cfqg);
1233 * Blk cgroup controller notification saying that blkio_group object is being
1234 * delinked as associated cgroup object is going away. That also means that
1235 * no new IO will come in this group. So get rid of this group as soon as
1236 * any pending IO in the group is finished.
1238 * This function is called under rcu_read_lock(). key is the rcu protected
1239 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1242 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1243 * it should not be NULL as even if elevator was exiting, cgroup deltion
1244 * path got to it first.
1246 static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1248 unsigned long flags;
1249 struct cfq_data *cfqd = key;
1251 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1252 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1253 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1256 #else /* GROUP_IOSCHED */
1257 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
1259 return &cfqd->root_group;
1262 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1268 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1272 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1273 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1275 #endif /* GROUP_IOSCHED */
1278 * The cfqd->service_trees holds all pending cfq_queue's that have
1279 * requests waiting to be processed. It is sorted in the order that
1280 * we will service the queues.
1282 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1285 struct rb_node **p, *parent;
1286 struct cfq_queue *__cfqq;
1287 unsigned long rb_key;
1288 struct cfq_rb_root *service_tree;
1292 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1294 if (cfq_class_idle(cfqq)) {
1295 rb_key = CFQ_IDLE_DELAY;
1296 parent = rb_last(&service_tree->rb);
1297 if (parent && parent != &cfqq->rb_node) {
1298 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1299 rb_key += __cfqq->rb_key;
1302 } else if (!add_front) {
1304 * Get our rb key offset. Subtract any residual slice
1305 * value carried from last service. A negative resid
1306 * count indicates slice overrun, and this should position
1307 * the next service time further away in the tree.
1309 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1310 rb_key -= cfqq->slice_resid;
1311 cfqq->slice_resid = 0;
1314 __cfqq = cfq_rb_first(service_tree);
1315 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1318 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1321 * same position, nothing more to do
1323 if (rb_key == cfqq->rb_key &&
1324 cfqq->service_tree == service_tree)
1327 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1328 cfqq->service_tree = NULL;
1333 cfqq->service_tree = service_tree;
1334 p = &service_tree->rb.rb_node;
1339 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1342 * sort by key, that represents service time.
1344 if (time_before(rb_key, __cfqq->rb_key))
1347 n = &(*p)->rb_right;
1355 service_tree->left = &cfqq->rb_node;
1357 cfqq->rb_key = rb_key;
1358 rb_link_node(&cfqq->rb_node, parent, p);
1359 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1360 service_tree->count++;
1361 if (add_front || !new_cfqq)
1363 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1366 static struct cfq_queue *
1367 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1368 sector_t sector, struct rb_node **ret_parent,
1369 struct rb_node ***rb_link)
1371 struct rb_node **p, *parent;
1372 struct cfq_queue *cfqq = NULL;
1380 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1383 * Sort strictly based on sector. Smallest to the left,
1384 * largest to the right.
1386 if (sector > blk_rq_pos(cfqq->next_rq))
1387 n = &(*p)->rb_right;
1388 else if (sector < blk_rq_pos(cfqq->next_rq))
1396 *ret_parent = parent;
1402 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1404 struct rb_node **p, *parent;
1405 struct cfq_queue *__cfqq;
1408 rb_erase(&cfqq->p_node, cfqq->p_root);
1409 cfqq->p_root = NULL;
1412 if (cfq_class_idle(cfqq))
1417 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1418 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1419 blk_rq_pos(cfqq->next_rq), &parent, &p);
1421 rb_link_node(&cfqq->p_node, parent, p);
1422 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1424 cfqq->p_root = NULL;
1428 * Update cfqq's position in the service tree.
1430 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1433 * Resorting requires the cfqq to be on the RR list already.
1435 if (cfq_cfqq_on_rr(cfqq)) {
1436 cfq_service_tree_add(cfqd, cfqq, 0);
1437 cfq_prio_tree_add(cfqd, cfqq);
1442 * add to busy list of queues for service, trying to be fair in ordering
1443 * the pending list according to last request service
1445 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1447 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1448 BUG_ON(cfq_cfqq_on_rr(cfqq));
1449 cfq_mark_cfqq_on_rr(cfqq);
1450 cfqd->busy_queues++;
1451 if (cfq_cfqq_sync(cfqq))
1452 cfqd->busy_sync_queues++;
1454 cfq_resort_rr_list(cfqd, cfqq);
1458 * Called when the cfqq no longer has requests pending, remove it from
1461 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1463 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1464 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1465 cfq_clear_cfqq_on_rr(cfqq);
1467 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1468 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1469 cfqq->service_tree = NULL;
1472 rb_erase(&cfqq->p_node, cfqq->p_root);
1473 cfqq->p_root = NULL;
1476 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1477 BUG_ON(!cfqd->busy_queues);
1478 cfqd->busy_queues--;
1479 if (cfq_cfqq_sync(cfqq))
1480 cfqd->busy_sync_queues--;
1484 * rb tree support functions
1486 static void cfq_del_rq_rb(struct request *rq)
1488 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1489 const int sync = rq_is_sync(rq);
1491 BUG_ON(!cfqq->queued[sync]);
1492 cfqq->queued[sync]--;
1494 elv_rb_del(&cfqq->sort_list, rq);
1496 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1498 * Queue will be deleted from service tree when we actually
1499 * expire it later. Right now just remove it from prio tree
1503 rb_erase(&cfqq->p_node, cfqq->p_root);
1504 cfqq->p_root = NULL;
1509 static void cfq_add_rq_rb(struct request *rq)
1511 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1512 struct cfq_data *cfqd = cfqq->cfqd;
1513 struct request *prev;
1515 cfqq->queued[rq_is_sync(rq)]++;
1517 elv_rb_add(&cfqq->sort_list, rq);
1519 if (!cfq_cfqq_on_rr(cfqq))
1520 cfq_add_cfqq_rr(cfqd, cfqq);
1523 * check if this request is a better next-serve candidate
1525 prev = cfqq->next_rq;
1526 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1529 * adjust priority tree position, if ->next_rq changes
1531 if (prev != cfqq->next_rq)
1532 cfq_prio_tree_add(cfqd, cfqq);
1534 BUG_ON(!cfqq->next_rq);
1537 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1539 elv_rb_del(&cfqq->sort_list, rq);
1540 cfqq->queued[rq_is_sync(rq)]--;
1541 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1542 rq_data_dir(rq), rq_is_sync(rq));
1544 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1545 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1549 static struct request *
1550 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1552 struct task_struct *tsk = current;
1553 struct cfq_io_context *cic;
1554 struct cfq_queue *cfqq;
1556 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1560 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1562 sector_t sector = bio->bi_sector + bio_sectors(bio);
1564 return elv_rb_find(&cfqq->sort_list, sector);
1570 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1572 struct cfq_data *cfqd = q->elevator->elevator_data;
1574 cfqd->rq_in_driver++;
1575 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1576 cfqd->rq_in_driver);
1578 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1581 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1583 struct cfq_data *cfqd = q->elevator->elevator_data;
1585 WARN_ON(!cfqd->rq_in_driver);
1586 cfqd->rq_in_driver--;
1587 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1588 cfqd->rq_in_driver);
1591 static void cfq_remove_request(struct request *rq)
1593 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1595 if (cfqq->next_rq == rq)
1596 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1598 list_del_init(&rq->queuelist);
1601 cfqq->cfqd->rq_queued--;
1602 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1603 rq_data_dir(rq), rq_is_sync(rq));
1606 static int cfq_merge(struct request_queue *q, struct request **req,
1609 struct cfq_data *cfqd = q->elevator->elevator_data;
1610 struct request *__rq;
1612 __rq = cfq_find_rq_fmerge(cfqd, bio);
1613 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1615 return ELEVATOR_FRONT_MERGE;
1618 return ELEVATOR_NO_MERGE;
1621 static void cfq_merged_request(struct request_queue *q, struct request *req,
1624 if (type == ELEVATOR_FRONT_MERGE) {
1625 struct cfq_queue *cfqq = RQ_CFQQ(req);
1627 cfq_reposition_rq_rb(cfqq, req);
1631 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1634 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1635 bio_data_dir(bio), cfq_bio_sync(bio));
1639 cfq_merged_requests(struct request_queue *q, struct request *rq,
1640 struct request *next)
1642 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1644 * reposition in fifo if next is older than rq
1646 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1647 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1648 list_move(&rq->queuelist, &next->queuelist);
1649 rq_set_fifo_time(rq, rq_fifo_time(next));
1652 if (cfqq->next_rq == next)
1654 cfq_remove_request(next);
1655 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1656 rq_data_dir(next), rq_is_sync(next));
1659 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1662 struct cfq_data *cfqd = q->elevator->elevator_data;
1663 struct cfq_io_context *cic;
1664 struct cfq_queue *cfqq;
1667 * Disallow merge of a sync bio into an async request.
1669 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1673 * Lookup the cfqq that this bio will be queued with. Allow
1674 * merge only if rq is queued there.
1676 cic = cfq_cic_lookup(cfqd, current->io_context);
1680 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1681 return cfqq == RQ_CFQQ(rq);
1684 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1686 del_timer(&cfqd->idle_slice_timer);
1687 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1690 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1691 struct cfq_queue *cfqq)
1694 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1695 cfqd->serving_prio, cfqd->serving_type);
1696 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1697 cfqq->slice_start = 0;
1698 cfqq->dispatch_start = jiffies;
1699 cfqq->allocated_slice = 0;
1700 cfqq->slice_end = 0;
1701 cfqq->slice_dispatch = 0;
1702 cfqq->nr_sectors = 0;
1704 cfq_clear_cfqq_wait_request(cfqq);
1705 cfq_clear_cfqq_must_dispatch(cfqq);
1706 cfq_clear_cfqq_must_alloc_slice(cfqq);
1707 cfq_clear_cfqq_fifo_expire(cfqq);
1708 cfq_mark_cfqq_slice_new(cfqq);
1710 cfq_del_timer(cfqd, cfqq);
1713 cfqd->active_queue = cfqq;
1717 * current cfqq expired its slice (or was too idle), select new one
1720 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1723 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1725 if (cfq_cfqq_wait_request(cfqq))
1726 cfq_del_timer(cfqd, cfqq);
1728 cfq_clear_cfqq_wait_request(cfqq);
1729 cfq_clear_cfqq_wait_busy(cfqq);
1732 * If this cfqq is shared between multiple processes, check to
1733 * make sure that those processes are still issuing I/Os within
1734 * the mean seek distance. If not, it may be time to break the
1735 * queues apart again.
1737 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1738 cfq_mark_cfqq_split_coop(cfqq);
1741 * store what was left of this slice, if the queue idled/timed out
1744 if (cfq_cfqq_slice_new(cfqq))
1745 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1747 cfqq->slice_resid = cfqq->slice_end - jiffies;
1748 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1751 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1753 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1754 cfq_del_cfqq_rr(cfqd, cfqq);
1756 cfq_resort_rr_list(cfqd, cfqq);
1758 if (cfqq == cfqd->active_queue)
1759 cfqd->active_queue = NULL;
1761 if (cfqd->active_cic) {
1762 put_io_context(cfqd->active_cic->ioc);
1763 cfqd->active_cic = NULL;
1767 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1769 struct cfq_queue *cfqq = cfqd->active_queue;
1772 __cfq_slice_expired(cfqd, cfqq, timed_out);
1776 * Get next queue for service. Unless we have a queue preemption,
1777 * we'll simply select the first cfqq in the service tree.
1779 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1781 struct cfq_rb_root *service_tree =
1782 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1783 cfqd->serving_type);
1785 if (!cfqd->rq_queued)
1788 /* There is nothing to dispatch */
1791 if (RB_EMPTY_ROOT(&service_tree->rb))
1793 return cfq_rb_first(service_tree);
1796 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1798 struct cfq_group *cfqg;
1799 struct cfq_queue *cfqq;
1801 struct cfq_rb_root *st;
1803 if (!cfqd->rq_queued)
1806 cfqg = cfq_get_next_cfqg(cfqd);
1810 for_each_cfqg_st(cfqg, i, j, st)
1811 if ((cfqq = cfq_rb_first(st)) != NULL)
1817 * Get and set a new active queue for service.
1819 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1820 struct cfq_queue *cfqq)
1823 cfqq = cfq_get_next_queue(cfqd);
1825 __cfq_set_active_queue(cfqd, cfqq);
1829 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1832 if (blk_rq_pos(rq) >= cfqd->last_position)
1833 return blk_rq_pos(rq) - cfqd->last_position;
1835 return cfqd->last_position - blk_rq_pos(rq);
1838 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1841 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1844 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1845 struct cfq_queue *cur_cfqq)
1847 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1848 struct rb_node *parent, *node;
1849 struct cfq_queue *__cfqq;
1850 sector_t sector = cfqd->last_position;
1852 if (RB_EMPTY_ROOT(root))
1856 * First, if we find a request starting at the end of the last
1857 * request, choose it.
1859 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1864 * If the exact sector wasn't found, the parent of the NULL leaf
1865 * will contain the closest sector.
1867 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1868 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1871 if (blk_rq_pos(__cfqq->next_rq) < sector)
1872 node = rb_next(&__cfqq->p_node);
1874 node = rb_prev(&__cfqq->p_node);
1878 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1879 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1887 * cur_cfqq - passed in so that we don't decide that the current queue is
1888 * closely cooperating with itself.
1890 * So, basically we're assuming that that cur_cfqq has dispatched at least
1891 * one request, and that cfqd->last_position reflects a position on the disk
1892 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1895 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1896 struct cfq_queue *cur_cfqq)
1898 struct cfq_queue *cfqq;
1900 if (cfq_class_idle(cur_cfqq))
1902 if (!cfq_cfqq_sync(cur_cfqq))
1904 if (CFQQ_SEEKY(cur_cfqq))
1908 * Don't search priority tree if it's the only queue in the group.
1910 if (cur_cfqq->cfqg->nr_cfqq == 1)
1914 * We should notice if some of the queues are cooperating, eg
1915 * working closely on the same area of the disk. In that case,
1916 * we can group them together and don't waste time idling.
1918 cfqq = cfqq_close(cfqd, cur_cfqq);
1922 /* If new queue belongs to different cfq_group, don't choose it */
1923 if (cur_cfqq->cfqg != cfqq->cfqg)
1927 * It only makes sense to merge sync queues.
1929 if (!cfq_cfqq_sync(cfqq))
1931 if (CFQQ_SEEKY(cfqq))
1935 * Do not merge queues of different priority classes
1937 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1944 * Determine whether we should enforce idle window for this queue.
1947 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1949 enum wl_prio_t prio = cfqq_prio(cfqq);
1950 struct cfq_rb_root *service_tree = cfqq->service_tree;
1952 BUG_ON(!service_tree);
1953 BUG_ON(!service_tree->count);
1955 if (!cfqd->cfq_slice_idle)
1958 /* We never do for idle class queues. */
1959 if (prio == IDLE_WORKLOAD)
1962 /* We do for queues that were marked with idle window flag. */
1963 if (cfq_cfqq_idle_window(cfqq) &&
1964 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1968 * Otherwise, we do only if they are the last ones
1969 * in their service tree.
1971 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
1972 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
1974 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1975 service_tree->count);
1979 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1981 struct cfq_queue *cfqq = cfqd->active_queue;
1982 struct cfq_io_context *cic;
1983 unsigned long sl, group_idle = 0;
1986 * SSD device without seek penalty, disable idling. But only do so
1987 * for devices that support queuing, otherwise we still have a problem
1988 * with sync vs async workloads.
1990 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1993 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1994 WARN_ON(cfq_cfqq_slice_new(cfqq));
1997 * idle is disabled, either manually or by past process history
1999 if (!cfq_should_idle(cfqd, cfqq)) {
2000 /* no queue idling. Check for group idling */
2001 if (cfqd->cfq_group_idle)
2002 group_idle = cfqd->cfq_group_idle;
2008 * still active requests from this queue, don't idle
2010 if (cfqq->dispatched)
2014 * task has exited, don't wait
2016 cic = cfqd->active_cic;
2017 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
2021 * If our average think time is larger than the remaining time
2022 * slice, then don't idle. This avoids overrunning the allotted
2025 if (sample_valid(cic->ttime.ttime_samples) &&
2026 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2027 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2028 cic->ttime.ttime_mean);
2032 /* There are other queues in the group, don't do group idle */
2033 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2036 cfq_mark_cfqq_wait_request(cfqq);
2039 sl = cfqd->cfq_group_idle;
2041 sl = cfqd->cfq_slice_idle;
2043 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2044 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
2045 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2046 group_idle ? 1 : 0);
2050 * Move request from internal lists to the request queue dispatch list.
2052 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2054 struct cfq_data *cfqd = q->elevator->elevator_data;
2055 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2057 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2059 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2060 cfq_remove_request(rq);
2062 (RQ_CFQG(rq))->dispatched++;
2063 elv_dispatch_sort(q, rq);
2065 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2066 cfqq->nr_sectors += blk_rq_sectors(rq);
2067 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2068 rq_data_dir(rq), rq_is_sync(rq));
2072 * return expired entry, or NULL to just start from scratch in rbtree
2074 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2076 struct request *rq = NULL;
2078 if (cfq_cfqq_fifo_expire(cfqq))
2081 cfq_mark_cfqq_fifo_expire(cfqq);
2083 if (list_empty(&cfqq->fifo))
2086 rq = rq_entry_fifo(cfqq->fifo.next);
2087 if (time_before(jiffies, rq_fifo_time(rq)))
2090 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2095 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2097 const int base_rq = cfqd->cfq_slice_async_rq;
2099 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2101 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2105 * Must be called with the queue_lock held.
2107 static int cfqq_process_refs(struct cfq_queue *cfqq)
2109 int process_refs, io_refs;
2111 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2112 process_refs = cfqq->ref - io_refs;
2113 BUG_ON(process_refs < 0);
2114 return process_refs;
2117 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2119 int process_refs, new_process_refs;
2120 struct cfq_queue *__cfqq;
2123 * If there are no process references on the new_cfqq, then it is
2124 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2125 * chain may have dropped their last reference (not just their
2126 * last process reference).
2128 if (!cfqq_process_refs(new_cfqq))
2131 /* Avoid a circular list and skip interim queue merges */
2132 while ((__cfqq = new_cfqq->new_cfqq)) {
2138 process_refs = cfqq_process_refs(cfqq);
2139 new_process_refs = cfqq_process_refs(new_cfqq);
2141 * If the process for the cfqq has gone away, there is no
2142 * sense in merging the queues.
2144 if (process_refs == 0 || new_process_refs == 0)
2148 * Merge in the direction of the lesser amount of work.
2150 if (new_process_refs >= process_refs) {
2151 cfqq->new_cfqq = new_cfqq;
2152 new_cfqq->ref += process_refs;
2154 new_cfqq->new_cfqq = cfqq;
2155 cfqq->ref += new_process_refs;
2159 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2160 struct cfq_group *cfqg, enum wl_prio_t prio)
2162 struct cfq_queue *queue;
2164 bool key_valid = false;
2165 unsigned long lowest_key = 0;
2166 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2168 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2169 /* select the one with lowest rb_key */
2170 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2172 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2173 lowest_key = queue->rb_key;
2182 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2186 struct cfq_rb_root *st;
2187 unsigned group_slice;
2188 enum wl_prio_t original_prio = cfqd->serving_prio;
2190 /* Choose next priority. RT > BE > IDLE */
2191 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2192 cfqd->serving_prio = RT_WORKLOAD;
2193 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2194 cfqd->serving_prio = BE_WORKLOAD;
2196 cfqd->serving_prio = IDLE_WORKLOAD;
2197 cfqd->workload_expires = jiffies + 1;
2201 if (original_prio != cfqd->serving_prio)
2205 * For RT and BE, we have to choose also the type
2206 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2209 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2213 * check workload expiration, and that we still have other queues ready
2215 if (count && !time_after(jiffies, cfqd->workload_expires))
2219 /* otherwise select new workload type */
2220 cfqd->serving_type =
2221 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2222 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2226 * the workload slice is computed as a fraction of target latency
2227 * proportional to the number of queues in that workload, over
2228 * all the queues in the same priority class
2230 group_slice = cfq_group_slice(cfqd, cfqg);
2232 slice = group_slice * count /
2233 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2234 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2236 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2240 * Async queues are currently system wide. Just taking
2241 * proportion of queues with-in same group will lead to higher
2242 * async ratio system wide as generally root group is going
2243 * to have higher weight. A more accurate thing would be to
2244 * calculate system wide asnc/sync ratio.
2246 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2247 tmp = tmp/cfqd->busy_queues;
2248 slice = min_t(unsigned, slice, tmp);
2250 /* async workload slice is scaled down according to
2251 * the sync/async slice ratio. */
2252 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2254 /* sync workload slice is at least 2 * cfq_slice_idle */
2255 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2257 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2258 cfq_log(cfqd, "workload slice:%d", slice);
2259 cfqd->workload_expires = jiffies + slice;
2262 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2264 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2265 struct cfq_group *cfqg;
2267 if (RB_EMPTY_ROOT(&st->rb))
2269 cfqg = cfq_rb_first_group(st);
2270 update_min_vdisktime(st);
2274 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2276 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2278 cfqd->serving_group = cfqg;
2280 /* Restore the workload type data */
2281 if (cfqg->saved_workload_slice) {
2282 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2283 cfqd->serving_type = cfqg->saved_workload;
2284 cfqd->serving_prio = cfqg->saved_serving_prio;
2286 cfqd->workload_expires = jiffies - 1;
2288 choose_service_tree(cfqd, cfqg);
2292 * Select a queue for service. If we have a current active queue,
2293 * check whether to continue servicing it, or retrieve and set a new one.
2295 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2297 struct cfq_queue *cfqq, *new_cfqq = NULL;
2299 cfqq = cfqd->active_queue;
2303 if (!cfqd->rq_queued)
2307 * We were waiting for group to get backlogged. Expire the queue
2309 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2313 * The active queue has run out of time, expire it and select new.
2315 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2317 * If slice had not expired at the completion of last request
2318 * we might not have turned on wait_busy flag. Don't expire
2319 * the queue yet. Allow the group to get backlogged.
2321 * The very fact that we have used the slice, that means we
2322 * have been idling all along on this queue and it should be
2323 * ok to wait for this request to complete.
2325 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2326 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2330 goto check_group_idle;
2334 * The active queue has requests and isn't expired, allow it to
2337 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2341 * If another queue has a request waiting within our mean seek
2342 * distance, let it run. The expire code will check for close
2343 * cooperators and put the close queue at the front of the service
2344 * tree. If possible, merge the expiring queue with the new cfqq.
2346 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2348 if (!cfqq->new_cfqq)
2349 cfq_setup_merge(cfqq, new_cfqq);
2354 * No requests pending. If the active queue still has requests in
2355 * flight or is idling for a new request, allow either of these
2356 * conditions to happen (or time out) before selecting a new queue.
2358 if (timer_pending(&cfqd->idle_slice_timer)) {
2364 * This is a deep seek queue, but the device is much faster than
2365 * the queue can deliver, don't idle
2367 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2368 (cfq_cfqq_slice_new(cfqq) ||
2369 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2370 cfq_clear_cfqq_deep(cfqq);
2371 cfq_clear_cfqq_idle_window(cfqq);
2374 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2380 * If group idle is enabled and there are requests dispatched from
2381 * this group, wait for requests to complete.
2384 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2385 && cfqq->cfqg->dispatched) {
2391 cfq_slice_expired(cfqd, 0);
2394 * Current queue expired. Check if we have to switch to a new
2398 cfq_choose_cfqg(cfqd);
2400 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2405 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2409 while (cfqq->next_rq) {
2410 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2414 BUG_ON(!list_empty(&cfqq->fifo));
2416 /* By default cfqq is not expired if it is empty. Do it explicitly */
2417 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2422 * Drain our current requests. Used for barriers and when switching
2423 * io schedulers on-the-fly.
2425 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2427 struct cfq_queue *cfqq;
2430 /* Expire the timeslice of the current active queue first */
2431 cfq_slice_expired(cfqd, 0);
2432 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2433 __cfq_set_active_queue(cfqd, cfqq);
2434 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2437 BUG_ON(cfqd->busy_queues);
2439 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2443 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2444 struct cfq_queue *cfqq)
2446 /* the queue hasn't finished any request, can't estimate */
2447 if (cfq_cfqq_slice_new(cfqq))
2449 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2456 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2458 unsigned int max_dispatch;
2461 * Drain async requests before we start sync IO
2463 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2467 * If this is an async queue and we have sync IO in flight, let it wait
2469 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2472 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2473 if (cfq_class_idle(cfqq))
2477 * Does this cfqq already have too much IO in flight?
2479 if (cfqq->dispatched >= max_dispatch) {
2480 bool promote_sync = false;
2482 * idle queue must always only have a single IO in flight
2484 if (cfq_class_idle(cfqq))
2488 * If there is only one sync queue
2489 * we can ignore async queue here and give the sync
2490 * queue no dispatch limit. The reason is a sync queue can
2491 * preempt async queue, limiting the sync queue doesn't make
2492 * sense. This is useful for aiostress test.
2494 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2495 promote_sync = true;
2498 * We have other queues, don't allow more IO from this one
2500 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2505 * Sole queue user, no limit
2507 if (cfqd->busy_queues == 1 || promote_sync)
2511 * Normally we start throttling cfqq when cfq_quantum/2
2512 * requests have been dispatched. But we can drive
2513 * deeper queue depths at the beginning of slice
2514 * subjected to upper limit of cfq_quantum.
2516 max_dispatch = cfqd->cfq_quantum;
2520 * Async queues must wait a bit before being allowed dispatch.
2521 * We also ramp up the dispatch depth gradually for async IO,
2522 * based on the last sync IO we serviced
2524 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2525 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2528 depth = last_sync / cfqd->cfq_slice[1];
2529 if (!depth && !cfqq->dispatched)
2531 if (depth < max_dispatch)
2532 max_dispatch = depth;
2536 * If we're below the current max, allow a dispatch
2538 return cfqq->dispatched < max_dispatch;
2542 * Dispatch a request from cfqq, moving them to the request queue
2545 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2549 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2551 if (!cfq_may_dispatch(cfqd, cfqq))
2555 * follow expired path, else get first next available
2557 rq = cfq_check_fifo(cfqq);
2562 * insert request into driver dispatch list
2564 cfq_dispatch_insert(cfqd->queue, rq);
2566 if (!cfqd->active_cic) {
2567 struct cfq_io_context *cic = RQ_CIC(rq);
2569 atomic_long_inc(&cic->ioc->refcount);
2570 cfqd->active_cic = cic;
2577 * Find the cfqq that we need to service and move a request from that to the
2580 static int cfq_dispatch_requests(struct request_queue *q, int force)
2582 struct cfq_data *cfqd = q->elevator->elevator_data;
2583 struct cfq_queue *cfqq;
2585 if (!cfqd->busy_queues)
2588 if (unlikely(force))
2589 return cfq_forced_dispatch(cfqd);
2591 cfqq = cfq_select_queue(cfqd);
2596 * Dispatch a request from this cfqq, if it is allowed
2598 if (!cfq_dispatch_request(cfqd, cfqq))
2601 cfqq->slice_dispatch++;
2602 cfq_clear_cfqq_must_dispatch(cfqq);
2605 * expire an async queue immediately if it has used up its slice. idle
2606 * queue always expire after 1 dispatch round.
2608 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2609 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2610 cfq_class_idle(cfqq))) {
2611 cfqq->slice_end = jiffies + 1;
2612 cfq_slice_expired(cfqd, 0);
2615 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2620 * task holds one reference to the queue, dropped when task exits. each rq
2621 * in-flight on this queue also holds a reference, dropped when rq is freed.
2623 * Each cfq queue took a reference on the parent group. Drop it now.
2624 * queue lock must be held here.
2626 static void cfq_put_queue(struct cfq_queue *cfqq)
2628 struct cfq_data *cfqd = cfqq->cfqd;
2629 struct cfq_group *cfqg;
2631 BUG_ON(cfqq->ref <= 0);
2637 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2638 BUG_ON(rb_first(&cfqq->sort_list));
2639 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2642 if (unlikely(cfqd->active_queue == cfqq)) {
2643 __cfq_slice_expired(cfqd, cfqq, 0);
2644 cfq_schedule_dispatch(cfqd);
2647 BUG_ON(cfq_cfqq_on_rr(cfqq));
2648 kmem_cache_free(cfq_pool, cfqq);
2653 * Call func for each cic attached to this ioc.
2656 call_for_each_cic(struct io_context *ioc,
2657 void (*func)(struct io_context *, struct cfq_io_context *))
2659 struct cfq_io_context *cic;
2660 struct hlist_node *n;
2664 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2670 static void cfq_cic_free_rcu(struct rcu_head *head)
2672 struct cfq_io_context *cic;
2674 cic = container_of(head, struct cfq_io_context, rcu_head);
2676 kmem_cache_free(cfq_ioc_pool, cic);
2677 elv_ioc_count_dec(cfq_ioc_count);
2681 * CFQ scheduler is exiting, grab exit lock and check
2682 * the pending io context count. If it hits zero,
2683 * complete ioc_gone and set it back to NULL
2685 spin_lock(&ioc_gone_lock);
2686 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2690 spin_unlock(&ioc_gone_lock);
2694 static void cfq_cic_free(struct cfq_io_context *cic)
2696 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2699 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2701 unsigned long flags;
2702 unsigned long dead_key = (unsigned long) cic->key;
2704 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2706 spin_lock_irqsave(&ioc->lock, flags);
2707 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2708 hlist_del_rcu(&cic->cic_list);
2709 spin_unlock_irqrestore(&ioc->lock, flags);
2715 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2716 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2717 * and ->trim() which is called with the task lock held
2719 static void cfq_free_io_context(struct io_context *ioc)
2722 * ioc->refcount is zero here, or we are called from elv_unregister(),
2723 * so no more cic's are allowed to be linked into this ioc. So it
2724 * should be ok to iterate over the known list, we will see all cic's
2725 * since no new ones are added.
2727 call_for_each_cic(ioc, cic_free_func);
2730 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2732 struct cfq_queue *__cfqq, *next;
2735 * If this queue was scheduled to merge with another queue, be
2736 * sure to drop the reference taken on that queue (and others in
2737 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2739 __cfqq = cfqq->new_cfqq;
2741 if (__cfqq == cfqq) {
2742 WARN(1, "cfqq->new_cfqq loop detected\n");
2745 next = __cfqq->new_cfqq;
2746 cfq_put_queue(__cfqq);
2751 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2753 if (unlikely(cfqq == cfqd->active_queue)) {
2754 __cfq_slice_expired(cfqd, cfqq, 0);
2755 cfq_schedule_dispatch(cfqd);
2758 cfq_put_cooperator(cfqq);
2760 cfq_put_queue(cfqq);
2763 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2764 struct cfq_io_context *cic)
2766 struct io_context *ioc = cic->ioc;
2768 list_del_init(&cic->queue_list);
2771 * Make sure dead mark is seen for dead queues
2774 cic->key = cfqd_dead_key(cfqd);
2777 if (rcu_dereference(ioc->ioc_data) == cic) {
2779 spin_lock(&ioc->lock);
2780 rcu_assign_pointer(ioc->ioc_data, NULL);
2781 spin_unlock(&ioc->lock);
2785 if (cic->cfqq[BLK_RW_ASYNC]) {
2786 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2787 cic->cfqq[BLK_RW_ASYNC] = NULL;
2790 if (cic->cfqq[BLK_RW_SYNC]) {
2791 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2792 cic->cfqq[BLK_RW_SYNC] = NULL;
2796 static void cfq_exit_single_io_context(struct io_context *ioc,
2797 struct cfq_io_context *cic)
2799 struct cfq_data *cfqd = cic_to_cfqd(cic);
2802 struct request_queue *q = cfqd->queue;
2803 unsigned long flags;
2805 spin_lock_irqsave(q->queue_lock, flags);
2808 * Ensure we get a fresh copy of the ->key to prevent
2809 * race between exiting task and queue
2811 smp_read_barrier_depends();
2812 if (cic->key == cfqd)
2813 __cfq_exit_single_io_context(cfqd, cic);
2815 spin_unlock_irqrestore(q->queue_lock, flags);
2820 * The process that ioc belongs to has exited, we need to clean up
2821 * and put the internal structures we have that belongs to that process.
2823 static void cfq_exit_io_context(struct io_context *ioc)
2825 call_for_each_cic(ioc, cfq_exit_single_io_context);
2828 static struct cfq_io_context *
2829 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2831 struct cfq_io_context *cic;
2833 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2836 cic->ttime.last_end_request = jiffies;
2837 INIT_LIST_HEAD(&cic->queue_list);
2838 INIT_HLIST_NODE(&cic->cic_list);
2839 cic->dtor = cfq_free_io_context;
2840 cic->exit = cfq_exit_io_context;
2841 elv_ioc_count_inc(cfq_ioc_count);
2847 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2849 struct task_struct *tsk = current;
2852 if (!cfq_cfqq_prio_changed(cfqq))
2855 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2856 switch (ioprio_class) {
2858 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2859 case IOPRIO_CLASS_NONE:
2861 * no prio set, inherit CPU scheduling settings
2863 cfqq->ioprio = task_nice_ioprio(tsk);
2864 cfqq->ioprio_class = task_nice_ioclass(tsk);
2866 case IOPRIO_CLASS_RT:
2867 cfqq->ioprio = task_ioprio(ioc);
2868 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2870 case IOPRIO_CLASS_BE:
2871 cfqq->ioprio = task_ioprio(ioc);
2872 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2874 case IOPRIO_CLASS_IDLE:
2875 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2877 cfq_clear_cfqq_idle_window(cfqq);
2882 * keep track of original prio settings in case we have to temporarily
2883 * elevate the priority of this queue
2885 cfqq->org_ioprio = cfqq->ioprio;
2886 cfq_clear_cfqq_prio_changed(cfqq);
2889 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2891 struct cfq_data *cfqd = cic_to_cfqd(cic);
2892 struct cfq_queue *cfqq;
2893 unsigned long flags;
2895 if (unlikely(!cfqd))
2898 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2900 cfqq = cic->cfqq[BLK_RW_ASYNC];
2902 struct cfq_queue *new_cfqq;
2903 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2906 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2907 cfq_put_queue(cfqq);
2911 cfqq = cic->cfqq[BLK_RW_SYNC];
2913 cfq_mark_cfqq_prio_changed(cfqq);
2915 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2918 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2920 call_for_each_cic(ioc, changed_ioprio);
2921 ioc->ioprio_changed = 0;
2924 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2925 pid_t pid, bool is_sync)
2927 RB_CLEAR_NODE(&cfqq->rb_node);
2928 RB_CLEAR_NODE(&cfqq->p_node);
2929 INIT_LIST_HEAD(&cfqq->fifo);
2934 cfq_mark_cfqq_prio_changed(cfqq);
2937 if (!cfq_class_idle(cfqq))
2938 cfq_mark_cfqq_idle_window(cfqq);
2939 cfq_mark_cfqq_sync(cfqq);
2944 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2945 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2947 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2948 struct cfq_data *cfqd = cic_to_cfqd(cic);
2949 unsigned long flags;
2950 struct request_queue *q;
2952 if (unlikely(!cfqd))
2957 spin_lock_irqsave(q->queue_lock, flags);
2961 * Drop reference to sync queue. A new sync queue will be
2962 * assigned in new group upon arrival of a fresh request.
2964 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2965 cic_set_cfqq(cic, NULL, 1);
2966 cfq_put_queue(sync_cfqq);
2969 spin_unlock_irqrestore(q->queue_lock, flags);
2972 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2974 call_for_each_cic(ioc, changed_cgroup);
2975 ioc->cgroup_changed = 0;
2977 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2979 static struct cfq_queue *
2980 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2981 struct io_context *ioc, gfp_t gfp_mask)
2983 struct cfq_queue *cfqq, *new_cfqq = NULL;
2984 struct cfq_io_context *cic;
2985 struct cfq_group *cfqg;
2988 cfqg = cfq_get_cfqg(cfqd);
2989 cic = cfq_cic_lookup(cfqd, ioc);
2990 /* cic always exists here */
2991 cfqq = cic_to_cfqq(cic, is_sync);
2994 * Always try a new alloc if we fell back to the OOM cfqq
2995 * originally, since it should just be a temporary situation.
2997 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3002 } else if (gfp_mask & __GFP_WAIT) {
3003 spin_unlock_irq(cfqd->queue->queue_lock);
3004 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3005 gfp_mask | __GFP_ZERO,
3007 spin_lock_irq(cfqd->queue->queue_lock);
3011 cfqq = kmem_cache_alloc_node(cfq_pool,
3012 gfp_mask | __GFP_ZERO,
3017 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3018 cfq_init_prio_data(cfqq, ioc);
3019 cfq_link_cfqq_cfqg(cfqq, cfqg);
3020 cfq_log_cfqq(cfqd, cfqq, "alloced");
3022 cfqq = &cfqd->oom_cfqq;
3026 kmem_cache_free(cfq_pool, new_cfqq);
3031 static struct cfq_queue **
3032 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3034 switch (ioprio_class) {
3035 case IOPRIO_CLASS_RT:
3036 return &cfqd->async_cfqq[0][ioprio];
3037 case IOPRIO_CLASS_BE:
3038 return &cfqd->async_cfqq[1][ioprio];
3039 case IOPRIO_CLASS_IDLE:
3040 return &cfqd->async_idle_cfqq;
3046 static struct cfq_queue *
3047 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
3050 const int ioprio = task_ioprio(ioc);
3051 const int ioprio_class = task_ioprio_class(ioc);
3052 struct cfq_queue **async_cfqq = NULL;
3053 struct cfq_queue *cfqq = NULL;
3056 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3061 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
3064 * pin the queue now that it's allocated, scheduler exit will prune it
3066 if (!is_sync && !(*async_cfqq)) {
3076 * We drop cfq io contexts lazily, so we may find a dead one.
3079 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3080 struct cfq_io_context *cic)
3082 unsigned long flags;
3084 WARN_ON(!list_empty(&cic->queue_list));
3085 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3087 spin_lock_irqsave(&ioc->lock, flags);
3089 BUG_ON(rcu_dereference_check(ioc->ioc_data,
3090 lockdep_is_held(&ioc->lock)) == cic);
3092 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3093 hlist_del_rcu(&cic->cic_list);
3094 spin_unlock_irqrestore(&ioc->lock, flags);
3099 static struct cfq_io_context *
3100 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3102 struct cfq_io_context *cic;
3103 unsigned long flags;
3111 * we maintain a last-hit cache, to avoid browsing over the tree
3113 cic = rcu_dereference(ioc->ioc_data);
3114 if (cic && cic->key == cfqd) {
3120 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3124 if (unlikely(cic->key != cfqd)) {
3125 cfq_drop_dead_cic(cfqd, ioc, cic);
3130 spin_lock_irqsave(&ioc->lock, flags);
3131 rcu_assign_pointer(ioc->ioc_data, cic);
3132 spin_unlock_irqrestore(&ioc->lock, flags);
3140 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3141 * the process specific cfq io context when entered from the block layer.
3142 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3144 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3145 struct cfq_io_context *cic, gfp_t gfp_mask)
3147 unsigned long flags;
3150 ret = radix_tree_preload(gfp_mask);
3155 spin_lock_irqsave(&ioc->lock, flags);
3156 ret = radix_tree_insert(&ioc->radix_root,
3157 cfqd->cic_index, cic);
3159 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3160 spin_unlock_irqrestore(&ioc->lock, flags);
3162 radix_tree_preload_end();
3165 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3166 list_add(&cic->queue_list, &cfqd->cic_list);
3167 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3172 printk(KERN_ERR "cfq: cic link failed!\n");
3178 * Setup general io context and cfq io context. There can be several cfq
3179 * io contexts per general io context, if this process is doing io to more
3180 * than one device managed by cfq.
3182 static struct cfq_io_context *
3183 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3185 struct io_context *ioc = NULL;
3186 struct cfq_io_context *cic;
3188 might_sleep_if(gfp_mask & __GFP_WAIT);
3190 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3194 cic = cfq_cic_lookup(cfqd, ioc);
3198 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3202 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3206 smp_read_barrier_depends();
3207 if (unlikely(ioc->ioprio_changed))
3208 cfq_ioc_set_ioprio(ioc);
3210 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3211 if (unlikely(ioc->cgroup_changed))
3212 cfq_ioc_set_cgroup(ioc);
3218 put_io_context(ioc);
3223 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3225 unsigned long elapsed = jiffies - ttime->last_end_request;
3226 elapsed = min(elapsed, 2UL * slice_idle);
3228 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3229 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3230 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3234 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3235 struct cfq_io_context *cic)
3237 if (cfq_cfqq_sync(cfqq)) {
3238 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3239 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3240 cfqd->cfq_slice_idle);
3245 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3249 sector_t n_sec = blk_rq_sectors(rq);
3250 if (cfqq->last_request_pos) {
3251 if (cfqq->last_request_pos < blk_rq_pos(rq))
3252 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3254 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3257 cfqq->seek_history <<= 1;
3258 if (blk_queue_nonrot(cfqd->queue))
3259 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3261 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3265 * Disable idle window if the process thinks too long or seeks so much that
3269 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3270 struct cfq_io_context *cic)
3272 int old_idle, enable_idle;
3275 * Don't idle for async or idle io prio class
3277 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3280 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3282 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3283 cfq_mark_cfqq_deep(cfqq);
3285 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3287 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3288 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3290 else if (sample_valid(cic->ttime.ttime_samples)) {
3291 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3297 if (old_idle != enable_idle) {
3298 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3300 cfq_mark_cfqq_idle_window(cfqq);
3302 cfq_clear_cfqq_idle_window(cfqq);
3307 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3308 * no or if we aren't sure, a 1 will cause a preempt.
3311 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3314 struct cfq_queue *cfqq;
3316 cfqq = cfqd->active_queue;
3320 if (cfq_class_idle(new_cfqq))
3323 if (cfq_class_idle(cfqq))
3327 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3329 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3333 * if the new request is sync, but the currently running queue is
3334 * not, let the sync request have priority.
3336 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3339 if (new_cfqq->cfqg != cfqq->cfqg)
3342 if (cfq_slice_used(cfqq))
3345 /* Allow preemption only if we are idling on sync-noidle tree */
3346 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3347 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3348 new_cfqq->service_tree->count == 2 &&
3349 RB_EMPTY_ROOT(&cfqq->sort_list))
3353 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3355 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3358 /* An idle queue should not be idle now for some reason */
3359 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3362 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3366 * if this request is as-good as one we would expect from the
3367 * current cfqq, let it preempt
3369 if (cfq_rq_close(cfqd, cfqq, rq))
3376 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3377 * let it have half of its nominal slice.
3379 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3381 struct cfq_queue *old_cfqq = cfqd->active_queue;
3383 cfq_log_cfqq(cfqd, cfqq, "preempt");
3384 cfq_slice_expired(cfqd, 1);
3387 * workload type is changed, don't save slice, otherwise preempt
3390 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3391 cfqq->cfqg->saved_workload_slice = 0;
3394 * Put the new queue at the front of the of the current list,
3395 * so we know that it will be selected next.
3397 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3399 cfq_service_tree_add(cfqd, cfqq, 1);
3401 cfqq->slice_end = 0;
3402 cfq_mark_cfqq_slice_new(cfqq);
3406 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3407 * something we should do about it
3410 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3413 struct cfq_io_context *cic = RQ_CIC(rq);
3417 cfq_update_io_thinktime(cfqd, cfqq, cic);
3418 cfq_update_io_seektime(cfqd, cfqq, rq);
3419 cfq_update_idle_window(cfqd, cfqq, cic);
3421 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3423 if (cfqq == cfqd->active_queue) {
3425 * Remember that we saw a request from this process, but
3426 * don't start queuing just yet. Otherwise we risk seeing lots
3427 * of tiny requests, because we disrupt the normal plugging
3428 * and merging. If the request is already larger than a single
3429 * page, let it rip immediately. For that case we assume that
3430 * merging is already done. Ditto for a busy system that
3431 * has other work pending, don't risk delaying until the
3432 * idle timer unplug to continue working.
3434 if (cfq_cfqq_wait_request(cfqq)) {
3435 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3436 cfqd->busy_queues > 1) {
3437 cfq_del_timer(cfqd, cfqq);
3438 cfq_clear_cfqq_wait_request(cfqq);
3439 __blk_run_queue(cfqd->queue);
3441 cfq_blkiocg_update_idle_time_stats(
3443 cfq_mark_cfqq_must_dispatch(cfqq);
3446 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3448 * not the active queue - expire current slice if it is
3449 * idle and has expired it's mean thinktime or this new queue
3450 * has some old slice time left and is of higher priority or
3451 * this new queue is RT and the current one is BE
3453 cfq_preempt_queue(cfqd, cfqq);
3454 __blk_run_queue(cfqd->queue);
3458 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3460 struct cfq_data *cfqd = q->elevator->elevator_data;
3461 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3463 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3464 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3466 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3467 list_add_tail(&rq->queuelist, &cfqq->fifo);
3469 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3470 &cfqd->serving_group->blkg, rq_data_dir(rq),
3472 cfq_rq_enqueued(cfqd, cfqq, rq);
3476 * Update hw_tag based on peak queue depth over 50 samples under
3479 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3481 struct cfq_queue *cfqq = cfqd->active_queue;
3483 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3484 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3486 if (cfqd->hw_tag == 1)
3489 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3490 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3494 * If active queue hasn't enough requests and can idle, cfq might not
3495 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3498 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3499 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3500 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3503 if (cfqd->hw_tag_samples++ < 50)
3506 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3512 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3514 struct cfq_io_context *cic = cfqd->active_cic;
3516 /* If the queue already has requests, don't wait */
3517 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3520 /* If there are other queues in the group, don't wait */
3521 if (cfqq->cfqg->nr_cfqq > 1)
3524 if (cfq_slice_used(cfqq))
3527 /* if slice left is less than think time, wait busy */
3528 if (cic && sample_valid(cic->ttime.ttime_samples)
3529 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3533 * If think times is less than a jiffy than ttime_mean=0 and above
3534 * will not be true. It might happen that slice has not expired yet
3535 * but will expire soon (4-5 ns) during select_queue(). To cover the
3536 * case where think time is less than a jiffy, mark the queue wait
3537 * busy if only 1 jiffy is left in the slice.
3539 if (cfqq->slice_end - jiffies == 1)
3545 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3547 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3548 struct cfq_data *cfqd = cfqq->cfqd;
3549 const int sync = rq_is_sync(rq);
3553 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3554 !!(rq->cmd_flags & REQ_NOIDLE));
3556 cfq_update_hw_tag(cfqd);
3558 WARN_ON(!cfqd->rq_in_driver);
3559 WARN_ON(!cfqq->dispatched);
3560 cfqd->rq_in_driver--;
3562 (RQ_CFQG(rq))->dispatched--;
3563 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3564 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3565 rq_data_dir(rq), rq_is_sync(rq));
3567 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3570 struct cfq_rb_root *service_tree;
3572 RQ_CIC(rq)->ttime.last_end_request = now;
3574 if (cfq_cfqq_on_rr(cfqq))
3575 service_tree = cfqq->service_tree;
3577 service_tree = service_tree_for(cfqq->cfqg,
3578 cfqq_prio(cfqq), cfqq_type(cfqq));
3579 service_tree->ttime.last_end_request = now;
3580 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3581 cfqd->last_delayed_sync = now;
3585 * If this is the active queue, check if it needs to be expired,
3586 * or if we want to idle in case it has no pending requests.
3588 if (cfqd->active_queue == cfqq) {
3589 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3591 if (cfq_cfqq_slice_new(cfqq)) {
3592 cfq_set_prio_slice(cfqd, cfqq);
3593 cfq_clear_cfqq_slice_new(cfqq);
3597 * Should we wait for next request to come in before we expire
3600 if (cfq_should_wait_busy(cfqd, cfqq)) {
3601 unsigned long extend_sl = cfqd->cfq_slice_idle;
3602 if (!cfqd->cfq_slice_idle)
3603 extend_sl = cfqd->cfq_group_idle;
3604 cfqq->slice_end = jiffies + extend_sl;
3605 cfq_mark_cfqq_wait_busy(cfqq);
3606 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3610 * Idling is not enabled on:
3612 * - idle-priority queues
3614 * - queues with still some requests queued
3615 * - when there is a close cooperator
3617 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3618 cfq_slice_expired(cfqd, 1);
3619 else if (sync && cfqq_empty &&
3620 !cfq_close_cooperator(cfqd, cfqq)) {
3621 cfq_arm_slice_timer(cfqd);
3625 if (!cfqd->rq_in_driver)
3626 cfq_schedule_dispatch(cfqd);
3629 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3631 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3632 cfq_mark_cfqq_must_alloc_slice(cfqq);
3633 return ELV_MQUEUE_MUST;
3636 return ELV_MQUEUE_MAY;
3639 static int cfq_may_queue(struct request_queue *q, int rw)
3641 struct cfq_data *cfqd = q->elevator->elevator_data;
3642 struct task_struct *tsk = current;
3643 struct cfq_io_context *cic;
3644 struct cfq_queue *cfqq;
3647 * don't force setup of a queue from here, as a call to may_queue
3648 * does not necessarily imply that a request actually will be queued.
3649 * so just lookup a possibly existing queue, or return 'may queue'
3652 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3654 return ELV_MQUEUE_MAY;
3656 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3658 cfq_init_prio_data(cfqq, cic->ioc);
3660 return __cfq_may_queue(cfqq);
3663 return ELV_MQUEUE_MAY;
3667 * queue lock held here
3669 static void cfq_put_request(struct request *rq)
3671 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3674 const int rw = rq_data_dir(rq);
3676 BUG_ON(!cfqq->allocated[rw]);
3677 cfqq->allocated[rw]--;
3679 put_io_context(RQ_CIC(rq)->ioc);
3681 rq->elevator_private[0] = NULL;
3682 rq->elevator_private[1] = NULL;
3684 /* Put down rq reference on cfqg */
3685 cfq_put_cfqg(RQ_CFQG(rq));
3686 rq->elevator_private[2] = NULL;
3688 cfq_put_queue(cfqq);
3692 static struct cfq_queue *
3693 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3694 struct cfq_queue *cfqq)
3696 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3697 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3698 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3699 cfq_put_queue(cfqq);
3700 return cic_to_cfqq(cic, 1);
3704 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3705 * was the last process referring to said cfqq.
3707 static struct cfq_queue *
3708 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3710 if (cfqq_process_refs(cfqq) == 1) {
3711 cfqq->pid = current->pid;
3712 cfq_clear_cfqq_coop(cfqq);
3713 cfq_clear_cfqq_split_coop(cfqq);
3717 cic_set_cfqq(cic, NULL, 1);
3719 cfq_put_cooperator(cfqq);
3721 cfq_put_queue(cfqq);
3725 * Allocate cfq data structures associated with this request.
3728 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3730 struct cfq_data *cfqd = q->elevator->elevator_data;
3731 struct cfq_io_context *cic;
3732 const int rw = rq_data_dir(rq);
3733 const bool is_sync = rq_is_sync(rq);
3734 struct cfq_queue *cfqq;
3735 unsigned long flags;
3737 might_sleep_if(gfp_mask & __GFP_WAIT);
3739 cic = cfq_get_io_context(cfqd, gfp_mask);
3741 spin_lock_irqsave(q->queue_lock, flags);
3747 cfqq = cic_to_cfqq(cic, is_sync);
3748 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3749 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3750 cic_set_cfqq(cic, cfqq, is_sync);
3753 * If the queue was seeky for too long, break it apart.
3755 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3756 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3757 cfqq = split_cfqq(cic, cfqq);
3763 * Check to see if this queue is scheduled to merge with
3764 * another, closely cooperating queue. The merging of
3765 * queues happens here as it must be done in process context.
3766 * The reference on new_cfqq was taken in merge_cfqqs.
3769 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3772 cfqq->allocated[rw]++;
3775 rq->elevator_private[0] = cic;
3776 rq->elevator_private[1] = cfqq;
3777 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3778 spin_unlock_irqrestore(q->queue_lock, flags);
3782 cfq_schedule_dispatch(cfqd);
3783 spin_unlock_irqrestore(q->queue_lock, flags);
3784 cfq_log(cfqd, "set_request fail");
3788 static void cfq_kick_queue(struct work_struct *work)
3790 struct cfq_data *cfqd =
3791 container_of(work, struct cfq_data, unplug_work);
3792 struct request_queue *q = cfqd->queue;
3794 spin_lock_irq(q->queue_lock);
3795 __blk_run_queue(cfqd->queue);
3796 spin_unlock_irq(q->queue_lock);
3800 * Timer running if the active_queue is currently idling inside its time slice
3802 static void cfq_idle_slice_timer(unsigned long data)
3804 struct cfq_data *cfqd = (struct cfq_data *) data;
3805 struct cfq_queue *cfqq;
3806 unsigned long flags;
3809 cfq_log(cfqd, "idle timer fired");
3811 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3813 cfqq = cfqd->active_queue;
3818 * We saw a request before the queue expired, let it through
3820 if (cfq_cfqq_must_dispatch(cfqq))
3826 if (cfq_slice_used(cfqq))
3830 * only expire and reinvoke request handler, if there are
3831 * other queues with pending requests
3833 if (!cfqd->busy_queues)
3837 * not expired and it has a request pending, let it dispatch
3839 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3843 * Queue depth flag is reset only when the idle didn't succeed
3845 cfq_clear_cfqq_deep(cfqq);
3848 cfq_slice_expired(cfqd, timed_out);
3850 cfq_schedule_dispatch(cfqd);
3852 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3855 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3857 del_timer_sync(&cfqd->idle_slice_timer);
3858 cancel_work_sync(&cfqd->unplug_work);
3861 static void cfq_put_async_queues(struct cfq_data *cfqd)
3865 for (i = 0; i < IOPRIO_BE_NR; i++) {
3866 if (cfqd->async_cfqq[0][i])
3867 cfq_put_queue(cfqd->async_cfqq[0][i]);
3868 if (cfqd->async_cfqq[1][i])
3869 cfq_put_queue(cfqd->async_cfqq[1][i]);
3872 if (cfqd->async_idle_cfqq)
3873 cfq_put_queue(cfqd->async_idle_cfqq);
3876 static void cfq_exit_queue(struct elevator_queue *e)
3878 struct cfq_data *cfqd = e->elevator_data;
3879 struct request_queue *q = cfqd->queue;
3882 cfq_shutdown_timer_wq(cfqd);
3884 spin_lock_irq(q->queue_lock);
3886 if (cfqd->active_queue)
3887 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3889 while (!list_empty(&cfqd->cic_list)) {
3890 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3891 struct cfq_io_context,
3894 __cfq_exit_single_io_context(cfqd, cic);
3897 cfq_put_async_queues(cfqd);
3898 cfq_release_cfq_groups(cfqd);
3901 * If there are groups which we could not unlink from blkcg list,
3902 * wait for a rcu period for them to be freed.
3904 if (cfqd->nr_blkcg_linked_grps)
3907 spin_unlock_irq(q->queue_lock);
3909 cfq_shutdown_timer_wq(cfqd);
3911 spin_lock(&cic_index_lock);
3912 ida_remove(&cic_index_ida, cfqd->cic_index);
3913 spin_unlock(&cic_index_lock);
3916 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3917 * Do this wait only if there are other unlinked groups out
3918 * there. This can happen if cgroup deletion path claimed the
3919 * responsibility of cleaning up a group before queue cleanup code
3922 * Do not call synchronize_rcu() unconditionally as there are drivers
3923 * which create/delete request queue hundreds of times during scan/boot
3924 * and synchronize_rcu() can take significant time and slow down boot.
3929 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3930 /* Free up per cpu stats for root group */
3931 free_percpu(cfqd->root_group.blkg.stats_cpu);
3936 static int cfq_alloc_cic_index(void)
3941 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3944 spin_lock(&cic_index_lock);
3945 error = ida_get_new(&cic_index_ida, &index);
3946 spin_unlock(&cic_index_lock);
3947 if (error && error != -EAGAIN)
3954 static void *cfq_init_queue(struct request_queue *q)
3956 struct cfq_data *cfqd;
3958 struct cfq_group *cfqg;
3959 struct cfq_rb_root *st;
3961 i = cfq_alloc_cic_index();
3965 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3967 spin_lock(&cic_index_lock);
3968 ida_remove(&cic_index_ida, i);
3969 spin_unlock(&cic_index_lock);
3974 * Don't need take queue_lock in the routine, since we are
3975 * initializing the ioscheduler, and nobody is using cfqd
3977 cfqd->cic_index = i;
3979 /* Init root service tree */
3980 cfqd->grp_service_tree = CFQ_RB_ROOT;
3982 /* Init root group */
3983 cfqg = &cfqd->root_group;
3984 for_each_cfqg_st(cfqg, i, j, st)
3986 RB_CLEAR_NODE(&cfqg->rb_node);
3988 /* Give preference to root group over other groups */
3989 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3991 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3993 * Set root group reference to 2. One reference will be dropped when
3994 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3995 * Other reference will remain there as we don't want to delete this
3996 * group as it is statically allocated and gets destroyed when
3997 * throtl_data goes away.
4001 if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
4009 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
4012 cfqd->nr_blkcg_linked_grps++;
4014 /* Add group on cfqd->cfqg_list */
4015 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
4018 * Not strictly needed (since RB_ROOT just clears the node and we
4019 * zeroed cfqd on alloc), but better be safe in case someone decides
4020 * to add magic to the rb code
4022 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4023 cfqd->prio_trees[i] = RB_ROOT;
4026 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4027 * Grab a permanent reference to it, so that the normal code flow
4028 * will not attempt to free it.
4030 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4031 cfqd->oom_cfqq.ref++;
4032 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
4034 INIT_LIST_HEAD(&cfqd->cic_list);
4038 init_timer(&cfqd->idle_slice_timer);
4039 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4040 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4042 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4044 cfqd->cfq_quantum = cfq_quantum;
4045 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4046 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4047 cfqd->cfq_back_max = cfq_back_max;
4048 cfqd->cfq_back_penalty = cfq_back_penalty;
4049 cfqd->cfq_slice[0] = cfq_slice_async;
4050 cfqd->cfq_slice[1] = cfq_slice_sync;
4051 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4052 cfqd->cfq_slice_idle = cfq_slice_idle;
4053 cfqd->cfq_group_idle = cfq_group_idle;
4054 cfqd->cfq_latency = 1;
4057 * we optimistically start assuming sync ops weren't delayed in last
4058 * second, in order to have larger depth for async operations.
4060 cfqd->last_delayed_sync = jiffies - HZ;
4064 static void cfq_slab_kill(void)
4067 * Caller already ensured that pending RCU callbacks are completed,
4068 * so we should have no busy allocations at this point.
4071 kmem_cache_destroy(cfq_pool);
4073 kmem_cache_destroy(cfq_ioc_pool);
4076 static int __init cfq_slab_setup(void)
4078 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4082 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
4093 * sysfs parts below -->
4096 cfq_var_show(unsigned int var, char *page)
4098 return sprintf(page, "%d\n", var);
4102 cfq_var_store(unsigned int *var, const char *page, size_t count)
4104 char *p = (char *) page;
4106 *var = simple_strtoul(p, &p, 10);
4110 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4111 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4113 struct cfq_data *cfqd = e->elevator_data; \
4114 unsigned int __data = __VAR; \
4116 __data = jiffies_to_msecs(__data); \
4117 return cfq_var_show(__data, (page)); \
4119 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4120 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4121 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4122 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4123 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4124 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4125 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4126 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4127 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4128 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4129 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4130 #undef SHOW_FUNCTION
4132 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4133 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4135 struct cfq_data *cfqd = e->elevator_data; \
4136 unsigned int __data; \
4137 int ret = cfq_var_store(&__data, (page), count); \
4138 if (__data < (MIN)) \
4140 else if (__data > (MAX)) \
4143 *(__PTR) = msecs_to_jiffies(__data); \
4145 *(__PTR) = __data; \
4148 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4149 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4151 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4153 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4154 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4156 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4157 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4158 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4159 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4160 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4162 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4163 #undef STORE_FUNCTION
4165 #define CFQ_ATTR(name) \
4166 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4168 static struct elv_fs_entry cfq_attrs[] = {
4170 CFQ_ATTR(fifo_expire_sync),
4171 CFQ_ATTR(fifo_expire_async),
4172 CFQ_ATTR(back_seek_max),
4173 CFQ_ATTR(back_seek_penalty),
4174 CFQ_ATTR(slice_sync),
4175 CFQ_ATTR(slice_async),
4176 CFQ_ATTR(slice_async_rq),
4177 CFQ_ATTR(slice_idle),
4178 CFQ_ATTR(group_idle),
4179 CFQ_ATTR(low_latency),
4183 static struct elevator_type iosched_cfq = {
4185 .elevator_merge_fn = cfq_merge,
4186 .elevator_merged_fn = cfq_merged_request,
4187 .elevator_merge_req_fn = cfq_merged_requests,
4188 .elevator_allow_merge_fn = cfq_allow_merge,
4189 .elevator_bio_merged_fn = cfq_bio_merged,
4190 .elevator_dispatch_fn = cfq_dispatch_requests,
4191 .elevator_add_req_fn = cfq_insert_request,
4192 .elevator_activate_req_fn = cfq_activate_request,
4193 .elevator_deactivate_req_fn = cfq_deactivate_request,
4194 .elevator_completed_req_fn = cfq_completed_request,
4195 .elevator_former_req_fn = elv_rb_former_request,
4196 .elevator_latter_req_fn = elv_rb_latter_request,
4197 .elevator_set_req_fn = cfq_set_request,
4198 .elevator_put_req_fn = cfq_put_request,
4199 .elevator_may_queue_fn = cfq_may_queue,
4200 .elevator_init_fn = cfq_init_queue,
4201 .elevator_exit_fn = cfq_exit_queue,
4202 .trim = cfq_free_io_context,
4204 .elevator_attrs = cfq_attrs,
4205 .elevator_name = "cfq",
4206 .elevator_owner = THIS_MODULE,
4209 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4210 static struct blkio_policy_type blkio_policy_cfq = {
4212 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4213 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4215 .plid = BLKIO_POLICY_PROP,
4218 static struct blkio_policy_type blkio_policy_cfq;
4221 static int __init cfq_init(void)
4224 * could be 0 on HZ < 1000 setups
4226 if (!cfq_slice_async)
4227 cfq_slice_async = 1;
4228 if (!cfq_slice_idle)
4231 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4232 if (!cfq_group_idle)
4237 if (cfq_slab_setup())
4240 elv_register(&iosched_cfq);
4241 blkio_policy_register(&blkio_policy_cfq);
4246 static void __exit cfq_exit(void)
4248 DECLARE_COMPLETION_ONSTACK(all_gone);
4249 blkio_policy_unregister(&blkio_policy_cfq);
4250 elv_unregister(&iosched_cfq);
4251 ioc_gone = &all_gone;
4252 /* ioc_gone's update must be visible before reading ioc_count */
4256 * this also protects us from entering cfq_slab_kill() with
4257 * pending RCU callbacks
4259 if (elv_ioc_count_read(cfq_ioc_count))
4260 wait_for_completion(&all_gone);
4261 ida_destroy(&cic_index_ida);
4265 module_init(cfq_init);
4266 module_exit(cfq_exit);
4268 MODULE_AUTHOR("Jens Axboe");
4269 MODULE_LICENSE("GPL");
4270 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");