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>
18 #include "blk-cgroup.h"
23 /* max queue in one round of service */
24 static const int cfq_quantum = 8;
25 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max = 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty = 2;
30 static const int cfq_slice_sync = HZ / 10;
31 static int cfq_slice_async = HZ / 25;
32 static const int cfq_slice_async_rq = 2;
33 static int cfq_slice_idle = HZ / 125;
34 static int cfq_group_idle = HZ / 125;
35 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36 static const int cfq_hist_divisor = 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache *cfq_pool;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
71 unsigned long last_end_request;
73 unsigned long ttime_total;
74 unsigned long ttime_samples;
75 unsigned long ttime_mean;
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.
89 struct cfq_ttime ttime;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
92 .ttime = {.last_end_request = jiffies,},}
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data *cfqd;
104 /* service_tree member */
105 struct rb_node rb_node;
106 /* service_tree key */
107 unsigned long rb_key;
108 /* prio tree member */
109 struct rb_node p_node;
110 /* prio tree root we belong to, if any */
111 struct rb_root *p_root;
112 /* sorted list of pending requests */
113 struct rb_root sort_list;
114 /* if fifo isn't expired, next request to serve */
115 struct request *next_rq;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start;
125 unsigned int allocated_slice;
126 unsigned int slice_dispatch;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start;
129 unsigned long slice_end;
132 /* pending priority requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio, org_ioprio;
139 unsigned short ioprio_class;
144 sector_t last_request_pos;
146 struct cfq_rb_root *service_tree;
147 struct cfq_queue *new_cfqq;
148 struct cfq_group *cfqg;
149 /* Number of sectors dispatched from queue in single dispatch round */
150 unsigned long nr_sectors;
154 * First index in the service_trees.
155 * IDLE is handled separately, so it has negative index
165 * Second index in the service_trees.
169 SYNC_NOIDLE_WORKLOAD = 1,
174 #ifdef CONFIG_CFQ_GROUP_IOSCHED
175 /* total bytes transferred */
176 struct blkg_rwstat service_bytes;
177 /* total IOs serviced, post merge */
178 struct blkg_rwstat serviced;
179 /* number of ios merged */
180 struct blkg_rwstat merged;
181 /* total time spent on device in ns, may not be accurate w/ queueing */
182 struct blkg_rwstat service_time;
183 /* total time spent waiting in scheduler queue in ns */
184 struct blkg_rwstat wait_time;
185 /* number of IOs queued up */
186 struct blkg_rwstat queued;
187 /* total sectors transferred */
188 struct blkg_stat sectors;
189 /* total disk time and nr sectors dispatched by this group */
190 struct blkg_stat time;
191 #ifdef CONFIG_DEBUG_BLK_CGROUP
192 /* time not charged to this cgroup */
193 struct blkg_stat unaccounted_time;
194 /* sum of number of ios queued across all samples */
195 struct blkg_stat avg_queue_size_sum;
196 /* count of samples taken for average */
197 struct blkg_stat avg_queue_size_samples;
198 /* how many times this group has been removed from service tree */
199 struct blkg_stat dequeue;
200 /* total time spent waiting for it to be assigned a timeslice. */
201 struct blkg_stat group_wait_time;
202 /* time spent idling for this blkcg_gq */
203 struct blkg_stat idle_time;
204 /* total time with empty current active q with other requests queued */
205 struct blkg_stat empty_time;
206 /* fields after this shouldn't be cleared on stat reset */
207 uint64_t start_group_wait_time;
208 uint64_t start_idle_time;
209 uint64_t start_empty_time;
211 #endif /* CONFIG_DEBUG_BLK_CGROUP */
212 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
215 /* This is per cgroup per device grouping structure */
217 /* must be the first member */
218 struct blkg_policy_data pd;
220 /* group service_tree member */
221 struct rb_node rb_node;
223 /* group service_tree key */
227 * The number of active cfqgs and sum of their weights under this
228 * cfqg. This covers this cfqg's leaf_weight and all children's
229 * weights, but does not cover weights of further descendants.
231 * If a cfqg is on the service tree, it's active. An active cfqg
232 * also activates its parent and contributes to the children_weight
236 unsigned int children_weight;
239 * vfraction is the fraction of vdisktime that the tasks in this
240 * cfqg are entitled to. This is determined by compounding the
241 * ratios walking up from this cfqg to the root.
243 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
244 * vfractions on a service tree is approximately 1. The sum may
245 * deviate a bit due to rounding errors and fluctuations caused by
246 * cfqgs entering and leaving the service tree.
248 unsigned int vfraction;
251 * There are two weights - (internal) weight is the weight of this
252 * cfqg against the sibling cfqgs. leaf_weight is the wight of
253 * this cfqg against the child cfqgs. For the root cfqg, both
254 * weights are kept in sync for backward compatibility.
257 unsigned int new_weight;
258 unsigned int dev_weight;
260 unsigned int leaf_weight;
261 unsigned int new_leaf_weight;
262 unsigned int dev_leaf_weight;
264 /* number of cfqq currently on this group */
268 * Per group busy queues average. Useful for workload slice calc. We
269 * create the array for each prio class but at run time it is used
270 * only for RT and BE class and slot for IDLE class remains unused.
271 * This is primarily done to avoid confusion and a gcc warning.
273 unsigned int busy_queues_avg[CFQ_PRIO_NR];
275 * rr lists of queues with requests. We maintain service trees for
276 * RT and BE classes. These trees are subdivided in subclasses
277 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
278 * class there is no subclassification and all the cfq queues go on
279 * a single tree service_tree_idle.
280 * Counts are embedded in the cfq_rb_root
282 struct cfq_rb_root service_trees[2][3];
283 struct cfq_rb_root service_tree_idle;
285 unsigned long saved_wl_slice;
286 enum wl_type_t saved_wl_type;
287 enum wl_class_t saved_wl_class;
289 /* number of requests that are on the dispatch list or inside driver */
291 struct cfq_ttime ttime;
292 struct cfqg_stats stats; /* stats for this cfqg */
293 struct cfqg_stats dead_stats; /* stats pushed from dead children */
297 struct io_cq icq; /* must be the first member */
298 struct cfq_queue *cfqq[2];
299 struct cfq_ttime ttime;
300 int ioprio; /* the current ioprio */
301 #ifdef CONFIG_CFQ_GROUP_IOSCHED
302 uint64_t blkcg_id; /* the current blkcg ID */
307 * Per block device queue structure
310 struct request_queue *queue;
311 /* Root service tree for cfq_groups */
312 struct cfq_rb_root grp_service_tree;
313 struct cfq_group *root_group;
316 * The priority currently being served
318 enum wl_class_t serving_wl_class;
319 enum wl_type_t serving_wl_type;
320 unsigned long workload_expires;
321 struct cfq_group *serving_group;
324 * Each priority tree is sorted by next_request position. These
325 * trees are used when determining if two or more queues are
326 * interleaving requests (see cfq_close_cooperator).
328 struct rb_root prio_trees[CFQ_PRIO_LISTS];
330 unsigned int busy_queues;
331 unsigned int busy_sync_queues;
337 * queue-depth detection
343 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
344 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
347 int hw_tag_est_depth;
348 unsigned int hw_tag_samples;
351 * idle window management
353 struct timer_list idle_slice_timer;
354 struct work_struct unplug_work;
356 struct cfq_queue *active_queue;
357 struct cfq_io_cq *active_cic;
360 * async queue for each priority case
362 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
363 struct cfq_queue *async_idle_cfqq;
365 sector_t last_position;
368 * tunables, see top of file
370 unsigned int cfq_quantum;
371 unsigned int cfq_fifo_expire[2];
372 unsigned int cfq_back_penalty;
373 unsigned int cfq_back_max;
374 unsigned int cfq_slice[2];
375 unsigned int cfq_slice_async_rq;
376 unsigned int cfq_slice_idle;
377 unsigned int cfq_group_idle;
378 unsigned int cfq_latency;
379 unsigned int cfq_target_latency;
382 * Fallback dummy cfqq for extreme OOM conditions
384 struct cfq_queue oom_cfqq;
386 unsigned long last_delayed_sync;
389 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
391 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
392 enum wl_class_t class,
398 if (class == IDLE_WORKLOAD)
399 return &cfqg->service_tree_idle;
401 return &cfqg->service_trees[class][type];
404 enum cfqq_state_flags {
405 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
406 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
407 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
408 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
409 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
410 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
411 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
412 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
413 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
414 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
415 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
416 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
417 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
420 #define CFQ_CFQQ_FNS(name) \
421 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
423 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
425 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
427 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
429 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
431 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
435 CFQ_CFQQ_FNS(wait_request);
436 CFQ_CFQQ_FNS(must_dispatch);
437 CFQ_CFQQ_FNS(must_alloc_slice);
438 CFQ_CFQQ_FNS(fifo_expire);
439 CFQ_CFQQ_FNS(idle_window);
440 CFQ_CFQQ_FNS(prio_changed);
441 CFQ_CFQQ_FNS(slice_new);
444 CFQ_CFQQ_FNS(split_coop);
446 CFQ_CFQQ_FNS(wait_busy);
449 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
451 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
454 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
456 return pd_to_blkg(&cfqg->pd);
459 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
461 /* cfqg stats flags */
462 enum cfqg_stats_flags {
463 CFQG_stats_waiting = 0,
468 #define CFQG_FLAG_FNS(name) \
469 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
471 stats->flags |= (1 << CFQG_stats_##name); \
473 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
475 stats->flags &= ~(1 << CFQG_stats_##name); \
477 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
479 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
482 CFQG_FLAG_FNS(waiting)
483 CFQG_FLAG_FNS(idling)
487 /* This should be called with the queue_lock held. */
488 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
490 unsigned long long now;
492 if (!cfqg_stats_waiting(stats))
496 if (time_after64(now, stats->start_group_wait_time))
497 blkg_stat_add(&stats->group_wait_time,
498 now - stats->start_group_wait_time);
499 cfqg_stats_clear_waiting(stats);
502 /* This should be called with the queue_lock held. */
503 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
504 struct cfq_group *curr_cfqg)
506 struct cfqg_stats *stats = &cfqg->stats;
508 if (cfqg_stats_waiting(stats))
510 if (cfqg == curr_cfqg)
512 stats->start_group_wait_time = sched_clock();
513 cfqg_stats_mark_waiting(stats);
516 /* This should be called with the queue_lock held. */
517 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
519 unsigned long long now;
521 if (!cfqg_stats_empty(stats))
525 if (time_after64(now, stats->start_empty_time))
526 blkg_stat_add(&stats->empty_time,
527 now - stats->start_empty_time);
528 cfqg_stats_clear_empty(stats);
531 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
533 blkg_stat_add(&cfqg->stats.dequeue, 1);
536 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
538 struct cfqg_stats *stats = &cfqg->stats;
540 if (blkg_rwstat_total(&stats->queued))
544 * group is already marked empty. This can happen if cfqq got new
545 * request in parent group and moved to this group while being added
546 * to service tree. Just ignore the event and move on.
548 if (cfqg_stats_empty(stats))
551 stats->start_empty_time = sched_clock();
552 cfqg_stats_mark_empty(stats);
555 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
557 struct cfqg_stats *stats = &cfqg->stats;
559 if (cfqg_stats_idling(stats)) {
560 unsigned long long now = sched_clock();
562 if (time_after64(now, stats->start_idle_time))
563 blkg_stat_add(&stats->idle_time,
564 now - stats->start_idle_time);
565 cfqg_stats_clear_idling(stats);
569 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
571 struct cfqg_stats *stats = &cfqg->stats;
573 BUG_ON(cfqg_stats_idling(stats));
575 stats->start_idle_time = sched_clock();
576 cfqg_stats_mark_idling(stats);
579 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
581 struct cfqg_stats *stats = &cfqg->stats;
583 blkg_stat_add(&stats->avg_queue_size_sum,
584 blkg_rwstat_total(&stats->queued));
585 blkg_stat_add(&stats->avg_queue_size_samples, 1);
586 cfqg_stats_update_group_wait_time(stats);
589 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
591 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
592 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
593 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
594 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
595 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
596 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
597 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
599 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
601 #ifdef CONFIG_CFQ_GROUP_IOSCHED
603 static struct blkcg_policy blkcg_policy_cfq;
605 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
607 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
610 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
612 struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
614 return pblkg ? blkg_to_cfqg(pblkg) : NULL;
617 static inline void cfqg_get(struct cfq_group *cfqg)
619 return blkg_get(cfqg_to_blkg(cfqg));
622 static inline void cfqg_put(struct cfq_group *cfqg)
624 return blkg_put(cfqg_to_blkg(cfqg));
627 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
630 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
631 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
632 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
633 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
637 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
640 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
641 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
644 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
645 struct cfq_group *curr_cfqg, int rw)
647 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
648 cfqg_stats_end_empty_time(&cfqg->stats);
649 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
652 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
653 unsigned long time, unsigned long unaccounted_time)
655 blkg_stat_add(&cfqg->stats.time, time);
656 #ifdef CONFIG_DEBUG_BLK_CGROUP
657 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
661 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
663 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
666 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
668 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
671 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
672 uint64_t bytes, int rw)
674 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
675 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
676 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
679 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
680 uint64_t start_time, uint64_t io_start_time, int rw)
682 struct cfqg_stats *stats = &cfqg->stats;
683 unsigned long long now = sched_clock();
685 if (time_after64(now, io_start_time))
686 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
687 if (time_after64(io_start_time, start_time))
688 blkg_rwstat_add(&stats->wait_time, rw,
689 io_start_time - start_time);
693 static void cfqg_stats_reset(struct cfqg_stats *stats)
695 /* queued stats shouldn't be cleared */
696 blkg_rwstat_reset(&stats->service_bytes);
697 blkg_rwstat_reset(&stats->serviced);
698 blkg_rwstat_reset(&stats->merged);
699 blkg_rwstat_reset(&stats->service_time);
700 blkg_rwstat_reset(&stats->wait_time);
701 blkg_stat_reset(&stats->time);
702 #ifdef CONFIG_DEBUG_BLK_CGROUP
703 blkg_stat_reset(&stats->unaccounted_time);
704 blkg_stat_reset(&stats->avg_queue_size_sum);
705 blkg_stat_reset(&stats->avg_queue_size_samples);
706 blkg_stat_reset(&stats->dequeue);
707 blkg_stat_reset(&stats->group_wait_time);
708 blkg_stat_reset(&stats->idle_time);
709 blkg_stat_reset(&stats->empty_time);
714 static void cfqg_stats_merge(struct cfqg_stats *to, struct cfqg_stats *from)
716 /* queued stats shouldn't be cleared */
717 blkg_rwstat_merge(&to->service_bytes, &from->service_bytes);
718 blkg_rwstat_merge(&to->serviced, &from->serviced);
719 blkg_rwstat_merge(&to->merged, &from->merged);
720 blkg_rwstat_merge(&to->service_time, &from->service_time);
721 blkg_rwstat_merge(&to->wait_time, &from->wait_time);
722 blkg_stat_merge(&from->time, &from->time);
723 #ifdef CONFIG_DEBUG_BLK_CGROUP
724 blkg_stat_merge(&to->unaccounted_time, &from->unaccounted_time);
725 blkg_stat_merge(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
726 blkg_stat_merge(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
727 blkg_stat_merge(&to->dequeue, &from->dequeue);
728 blkg_stat_merge(&to->group_wait_time, &from->group_wait_time);
729 blkg_stat_merge(&to->idle_time, &from->idle_time);
730 blkg_stat_merge(&to->empty_time, &from->empty_time);
735 * Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
736 * recursive stats can still account for the amount used by this cfqg after
739 static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
741 struct cfq_group *parent = cfqg_parent(cfqg);
743 lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
745 if (unlikely(!parent))
748 cfqg_stats_merge(&parent->dead_stats, &cfqg->stats);
749 cfqg_stats_merge(&parent->dead_stats, &cfqg->dead_stats);
750 cfqg_stats_reset(&cfqg->stats);
751 cfqg_stats_reset(&cfqg->dead_stats);
754 #else /* CONFIG_CFQ_GROUP_IOSCHED */
756 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
757 static inline void cfqg_get(struct cfq_group *cfqg) { }
758 static inline void cfqg_put(struct cfq_group *cfqg) { }
760 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
761 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
762 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
763 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
765 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
767 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
768 struct cfq_group *curr_cfqg, int rw) { }
769 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
770 unsigned long time, unsigned long unaccounted_time) { }
771 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
772 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
773 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
774 uint64_t bytes, int rw) { }
775 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
776 uint64_t start_time, uint64_t io_start_time, int rw) { }
778 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
780 #define cfq_log(cfqd, fmt, args...) \
781 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
783 /* Traverses through cfq group service trees */
784 #define for_each_cfqg_st(cfqg, i, j, st) \
785 for (i = 0; i <= IDLE_WORKLOAD; i++) \
786 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
787 : &cfqg->service_tree_idle; \
788 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
789 (i == IDLE_WORKLOAD && j == 0); \
790 j++, st = i < IDLE_WORKLOAD ? \
791 &cfqg->service_trees[i][j]: NULL) \
793 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
794 struct cfq_ttime *ttime, bool group_idle)
797 if (!sample_valid(ttime->ttime_samples))
800 slice = cfqd->cfq_group_idle;
802 slice = cfqd->cfq_slice_idle;
803 return ttime->ttime_mean > slice;
806 static inline bool iops_mode(struct cfq_data *cfqd)
809 * If we are not idling on queues and it is a NCQ drive, parallel
810 * execution of requests is on and measuring time is not possible
811 * in most of the cases until and unless we drive shallower queue
812 * depths and that becomes a performance bottleneck. In such cases
813 * switch to start providing fairness in terms of number of IOs.
815 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
821 static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
823 if (cfq_class_idle(cfqq))
824 return IDLE_WORKLOAD;
825 if (cfq_class_rt(cfqq))
831 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
833 if (!cfq_cfqq_sync(cfqq))
834 return ASYNC_WORKLOAD;
835 if (!cfq_cfqq_idle_window(cfqq))
836 return SYNC_NOIDLE_WORKLOAD;
837 return SYNC_WORKLOAD;
840 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
841 struct cfq_data *cfqd,
842 struct cfq_group *cfqg)
844 if (wl_class == IDLE_WORKLOAD)
845 return cfqg->service_tree_idle.count;
847 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
848 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
849 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
852 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
853 struct cfq_group *cfqg)
855 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
856 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
859 static void cfq_dispatch_insert(struct request_queue *, struct request *);
860 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
861 struct cfq_io_cq *cic, struct bio *bio,
864 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
866 /* cic->icq is the first member, %NULL will convert to %NULL */
867 return container_of(icq, struct cfq_io_cq, icq);
870 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
871 struct io_context *ioc)
874 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
878 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
880 return cic->cfqq[is_sync];
883 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
886 cic->cfqq[is_sync] = cfqq;
889 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
891 return cic->icq.q->elevator->elevator_data;
895 * We regard a request as SYNC, if it's either a read or has the SYNC bit
896 * set (in which case it could also be direct WRITE).
898 static inline bool cfq_bio_sync(struct bio *bio)
900 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
904 * scheduler run of queue, if there are requests pending and no one in the
905 * driver that will restart queueing
907 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
909 if (cfqd->busy_queues) {
910 cfq_log(cfqd, "schedule dispatch");
911 kblockd_schedule_work(&cfqd->unplug_work);
916 * Scale schedule slice based on io priority. Use the sync time slice only
917 * if a queue is marked sync and has sync io queued. A sync queue with async
918 * io only, should not get full sync slice length.
920 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
923 const int base_slice = cfqd->cfq_slice[sync];
925 WARN_ON(prio >= IOPRIO_BE_NR);
927 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
931 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
933 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
937 * cfqg_scale_charge - scale disk time charge according to cfqg weight
938 * @charge: disk time being charged
939 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
941 * Scale @charge according to @vfraction, which is in range (0, 1]. The
942 * scaling is inversely proportional.
944 * scaled = charge / vfraction
946 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
948 static inline u64 cfqg_scale_charge(unsigned long charge,
949 unsigned int vfraction)
951 u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
953 /* charge / vfraction */
954 c <<= CFQ_SERVICE_SHIFT;
955 do_div(c, vfraction);
959 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
961 s64 delta = (s64)(vdisktime - min_vdisktime);
963 min_vdisktime = vdisktime;
965 return min_vdisktime;
968 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
970 s64 delta = (s64)(vdisktime - min_vdisktime);
972 min_vdisktime = vdisktime;
974 return min_vdisktime;
977 static void update_min_vdisktime(struct cfq_rb_root *st)
979 struct cfq_group *cfqg;
982 cfqg = rb_entry_cfqg(st->left);
983 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
989 * get averaged number of queues of RT/BE priority.
990 * average is updated, with a formula that gives more weight to higher numbers,
991 * to quickly follows sudden increases and decrease slowly
994 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
995 struct cfq_group *cfqg, bool rt)
997 unsigned min_q, max_q;
998 unsigned mult = cfq_hist_divisor - 1;
999 unsigned round = cfq_hist_divisor / 2;
1000 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1002 min_q = min(cfqg->busy_queues_avg[rt], busy);
1003 max_q = max(cfqg->busy_queues_avg[rt], busy);
1004 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1006 return cfqg->busy_queues_avg[rt];
1009 static inline unsigned
1010 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1012 return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1015 static inline unsigned
1016 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1018 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
1019 if (cfqd->cfq_latency) {
1021 * interested queues (we consider only the ones with the same
1022 * priority class in the cfq group)
1024 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1025 cfq_class_rt(cfqq));
1026 unsigned sync_slice = cfqd->cfq_slice[1];
1027 unsigned expect_latency = sync_slice * iq;
1028 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1030 if (expect_latency > group_slice) {
1031 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
1032 /* scale low_slice according to IO priority
1033 * and sync vs async */
1034 unsigned low_slice =
1035 min(slice, base_low_slice * slice / sync_slice);
1036 /* the adapted slice value is scaled to fit all iqs
1037 * into the target latency */
1038 slice = max(slice * group_slice / expect_latency,
1046 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1048 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1050 cfqq->slice_start = jiffies;
1051 cfqq->slice_end = jiffies + slice;
1052 cfqq->allocated_slice = slice;
1053 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
1057 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1058 * isn't valid until the first request from the dispatch is activated
1059 * and the slice time set.
1061 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1063 if (cfq_cfqq_slice_new(cfqq))
1065 if (time_before(jiffies, cfqq->slice_end))
1072 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1073 * We choose the request that is closest to the head right now. Distance
1074 * behind the head is penalized and only allowed to a certain extent.
1076 static struct request *
1077 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1079 sector_t s1, s2, d1 = 0, d2 = 0;
1080 unsigned long back_max;
1081 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1082 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1083 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1085 if (rq1 == NULL || rq1 == rq2)
1090 if (rq_is_sync(rq1) != rq_is_sync(rq2))
1091 return rq_is_sync(rq1) ? rq1 : rq2;
1093 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1094 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1096 s1 = blk_rq_pos(rq1);
1097 s2 = blk_rq_pos(rq2);
1100 * by definition, 1KiB is 2 sectors
1102 back_max = cfqd->cfq_back_max * 2;
1105 * Strict one way elevator _except_ in the case where we allow
1106 * short backward seeks which are biased as twice the cost of a
1107 * similar forward seek.
1111 else if (s1 + back_max >= last)
1112 d1 = (last - s1) * cfqd->cfq_back_penalty;
1114 wrap |= CFQ_RQ1_WRAP;
1118 else if (s2 + back_max >= last)
1119 d2 = (last - s2) * cfqd->cfq_back_penalty;
1121 wrap |= CFQ_RQ2_WRAP;
1123 /* Found required data */
1126 * By doing switch() on the bit mask "wrap" we avoid having to
1127 * check two variables for all permutations: --> faster!
1130 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1146 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1149 * Since both rqs are wrapped,
1150 * start with the one that's further behind head
1151 * (--> only *one* back seek required),
1152 * since back seek takes more time than forward.
1162 * The below is leftmost cache rbtree addon
1164 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1166 /* Service tree is empty */
1171 root->left = rb_first(&root->rb);
1174 return rb_entry(root->left, struct cfq_queue, rb_node);
1179 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1182 root->left = rb_first(&root->rb);
1185 return rb_entry_cfqg(root->left);
1190 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1196 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1198 if (root->left == n)
1200 rb_erase_init(n, &root->rb);
1205 * would be nice to take fifo expire time into account as well
1207 static struct request *
1208 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1209 struct request *last)
1211 struct rb_node *rbnext = rb_next(&last->rb_node);
1212 struct rb_node *rbprev = rb_prev(&last->rb_node);
1213 struct request *next = NULL, *prev = NULL;
1215 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1218 prev = rb_entry_rq(rbprev);
1221 next = rb_entry_rq(rbnext);
1223 rbnext = rb_first(&cfqq->sort_list);
1224 if (rbnext && rbnext != &last->rb_node)
1225 next = rb_entry_rq(rbnext);
1228 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1231 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1232 struct cfq_queue *cfqq)
1235 * just an approximation, should be ok.
1237 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1238 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1242 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1244 return cfqg->vdisktime - st->min_vdisktime;
1248 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1250 struct rb_node **node = &st->rb.rb_node;
1251 struct rb_node *parent = NULL;
1252 struct cfq_group *__cfqg;
1253 s64 key = cfqg_key(st, cfqg);
1256 while (*node != NULL) {
1258 __cfqg = rb_entry_cfqg(parent);
1260 if (key < cfqg_key(st, __cfqg))
1261 node = &parent->rb_left;
1263 node = &parent->rb_right;
1269 st->left = &cfqg->rb_node;
1271 rb_link_node(&cfqg->rb_node, parent, node);
1272 rb_insert_color(&cfqg->rb_node, &st->rb);
1276 cfq_update_group_weight(struct cfq_group *cfqg)
1278 if (cfqg->new_weight) {
1279 cfqg->weight = cfqg->new_weight;
1280 cfqg->new_weight = 0;
1285 cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1287 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1289 if (cfqg->new_leaf_weight) {
1290 cfqg->leaf_weight = cfqg->new_leaf_weight;
1291 cfqg->new_leaf_weight = 0;
1296 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1298 unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
1299 struct cfq_group *pos = cfqg;
1300 struct cfq_group *parent;
1303 /* add to the service tree */
1304 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1306 cfq_update_group_leaf_weight(cfqg);
1307 __cfq_group_service_tree_add(st, cfqg);
1310 * Activate @cfqg and calculate the portion of vfraction @cfqg is
1311 * entitled to. vfraction is calculated by walking the tree
1312 * towards the root calculating the fraction it has at each level.
1313 * The compounded ratio is how much vfraction @cfqg owns.
1315 * Start with the proportion tasks in this cfqg has against active
1316 * children cfqgs - its leaf_weight against children_weight.
1318 propagate = !pos->nr_active++;
1319 pos->children_weight += pos->leaf_weight;
1320 vfr = vfr * pos->leaf_weight / pos->children_weight;
1323 * Compound ->weight walking up the tree. Both activation and
1324 * vfraction calculation are done in the same loop. Propagation
1325 * stops once an already activated node is met. vfraction
1326 * calculation should always continue to the root.
1328 while ((parent = cfqg_parent(pos))) {
1330 cfq_update_group_weight(pos);
1331 propagate = !parent->nr_active++;
1332 parent->children_weight += pos->weight;
1334 vfr = vfr * pos->weight / parent->children_weight;
1338 cfqg->vfraction = max_t(unsigned, vfr, 1);
1342 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1344 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1345 struct cfq_group *__cfqg;
1349 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1353 * Currently put the group at the end. Later implement something
1354 * so that groups get lesser vtime based on their weights, so that
1355 * if group does not loose all if it was not continuously backlogged.
1357 n = rb_last(&st->rb);
1359 __cfqg = rb_entry_cfqg(n);
1360 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1362 cfqg->vdisktime = st->min_vdisktime;
1363 cfq_group_service_tree_add(st, cfqg);
1367 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1369 struct cfq_group *pos = cfqg;
1373 * Undo activation from cfq_group_service_tree_add(). Deactivate
1374 * @cfqg and propagate deactivation upwards.
1376 propagate = !--pos->nr_active;
1377 pos->children_weight -= pos->leaf_weight;
1380 struct cfq_group *parent = cfqg_parent(pos);
1382 /* @pos has 0 nr_active at this point */
1383 WARN_ON_ONCE(pos->children_weight);
1389 propagate = !--parent->nr_active;
1390 parent->children_weight -= pos->weight;
1394 /* remove from the service tree */
1395 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1396 cfq_rb_erase(&cfqg->rb_node, st);
1400 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1402 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1404 BUG_ON(cfqg->nr_cfqq < 1);
1407 /* If there are other cfq queues under this group, don't delete it */
1411 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1412 cfq_group_service_tree_del(st, cfqg);
1413 cfqg->saved_wl_slice = 0;
1414 cfqg_stats_update_dequeue(cfqg);
1417 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1418 unsigned int *unaccounted_time)
1420 unsigned int slice_used;
1423 * Queue got expired before even a single request completed or
1424 * got expired immediately after first request completion.
1426 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1428 * Also charge the seek time incurred to the group, otherwise
1429 * if there are mutiple queues in the group, each can dispatch
1430 * a single request on seeky media and cause lots of seek time
1431 * and group will never know it.
1433 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1436 slice_used = jiffies - cfqq->slice_start;
1437 if (slice_used > cfqq->allocated_slice) {
1438 *unaccounted_time = slice_used - cfqq->allocated_slice;
1439 slice_used = cfqq->allocated_slice;
1441 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1442 *unaccounted_time += cfqq->slice_start -
1443 cfqq->dispatch_start;
1449 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1450 struct cfq_queue *cfqq)
1452 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1453 unsigned int used_sl, charge, unaccounted_sl = 0;
1454 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1455 - cfqg->service_tree_idle.count;
1458 BUG_ON(nr_sync < 0);
1459 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1461 if (iops_mode(cfqd))
1462 charge = cfqq->slice_dispatch;
1463 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1464 charge = cfqq->allocated_slice;
1467 * Can't update vdisktime while on service tree and cfqg->vfraction
1468 * is valid only while on it. Cache vfr, leave the service tree,
1469 * update vdisktime and go back on. The re-addition to the tree
1470 * will also update the weights as necessary.
1472 vfr = cfqg->vfraction;
1473 cfq_group_service_tree_del(st, cfqg);
1474 cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1475 cfq_group_service_tree_add(st, cfqg);
1477 /* This group is being expired. Save the context */
1478 if (time_after(cfqd->workload_expires, jiffies)) {
1479 cfqg->saved_wl_slice = cfqd->workload_expires
1481 cfqg->saved_wl_type = cfqd->serving_wl_type;
1482 cfqg->saved_wl_class = cfqd->serving_wl_class;
1484 cfqg->saved_wl_slice = 0;
1486 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1488 cfq_log_cfqq(cfqq->cfqd, cfqq,
1489 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1490 used_sl, cfqq->slice_dispatch, charge,
1491 iops_mode(cfqd), cfqq->nr_sectors);
1492 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1493 cfqg_stats_set_start_empty_time(cfqg);
1497 * cfq_init_cfqg_base - initialize base part of a cfq_group
1498 * @cfqg: cfq_group to initialize
1500 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1501 * is enabled or not.
1503 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1505 struct cfq_rb_root *st;
1508 for_each_cfqg_st(cfqg, i, j, st)
1510 RB_CLEAR_NODE(&cfqg->rb_node);
1512 cfqg->ttime.last_end_request = jiffies;
1515 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1516 static void cfqg_stats_init(struct cfqg_stats *stats)
1518 blkg_rwstat_init(&stats->service_bytes);
1519 blkg_rwstat_init(&stats->serviced);
1520 blkg_rwstat_init(&stats->merged);
1521 blkg_rwstat_init(&stats->service_time);
1522 blkg_rwstat_init(&stats->wait_time);
1523 blkg_rwstat_init(&stats->queued);
1525 blkg_stat_init(&stats->sectors);
1526 blkg_stat_init(&stats->time);
1528 #ifdef CONFIG_DEBUG_BLK_CGROUP
1529 blkg_stat_init(&stats->unaccounted_time);
1530 blkg_stat_init(&stats->avg_queue_size_sum);
1531 blkg_stat_init(&stats->avg_queue_size_samples);
1532 blkg_stat_init(&stats->dequeue);
1533 blkg_stat_init(&stats->group_wait_time);
1534 blkg_stat_init(&stats->idle_time);
1535 blkg_stat_init(&stats->empty_time);
1539 static void cfq_pd_init(struct blkcg_gq *blkg)
1541 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1543 cfq_init_cfqg_base(cfqg);
1544 cfqg->weight = blkg->blkcg->cfq_weight;
1545 cfqg->leaf_weight = blkg->blkcg->cfq_leaf_weight;
1546 cfqg_stats_init(&cfqg->stats);
1547 cfqg_stats_init(&cfqg->dead_stats);
1550 static void cfq_pd_offline(struct blkcg_gq *blkg)
1553 * @blkg is going offline and will be ignored by
1554 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1555 * that they don't get lost. If IOs complete after this point, the
1556 * stats for them will be lost. Oh well...
1558 cfqg_stats_xfer_dead(blkg_to_cfqg(blkg));
1561 /* offset delta from cfqg->stats to cfqg->dead_stats */
1562 static const int dead_stats_off_delta = offsetof(struct cfq_group, dead_stats) -
1563 offsetof(struct cfq_group, stats);
1565 /* to be used by recursive prfill, sums live and dead stats recursively */
1566 static u64 cfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
1570 sum += blkg_stat_recursive_sum(pd, off);
1571 sum += blkg_stat_recursive_sum(pd, off + dead_stats_off_delta);
1575 /* to be used by recursive prfill, sums live and dead rwstats recursively */
1576 static struct blkg_rwstat cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
1579 struct blkg_rwstat a, b;
1581 a = blkg_rwstat_recursive_sum(pd, off);
1582 b = blkg_rwstat_recursive_sum(pd, off + dead_stats_off_delta);
1583 blkg_rwstat_merge(&a, &b);
1587 static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
1589 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1591 cfqg_stats_reset(&cfqg->stats);
1592 cfqg_stats_reset(&cfqg->dead_stats);
1596 * Search for the cfq group current task belongs to. request_queue lock must
1599 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1600 struct blkcg *blkcg)
1602 struct request_queue *q = cfqd->queue;
1603 struct cfq_group *cfqg = NULL;
1605 /* avoid lookup for the common case where there's no blkcg */
1606 if (blkcg == &blkcg_root) {
1607 cfqg = cfqd->root_group;
1609 struct blkcg_gq *blkg;
1611 blkg = blkg_lookup_create(blkcg, q);
1613 cfqg = blkg_to_cfqg(blkg);
1619 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1621 /* Currently, all async queues are mapped to root group */
1622 if (!cfq_cfqq_sync(cfqq))
1623 cfqg = cfqq->cfqd->root_group;
1626 /* cfqq reference on cfqg */
1630 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1631 struct blkg_policy_data *pd, int off)
1633 struct cfq_group *cfqg = pd_to_cfqg(pd);
1635 if (!cfqg->dev_weight)
1637 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1640 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1642 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1643 cfqg_prfill_weight_device, &blkcg_policy_cfq,
1648 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1649 struct blkg_policy_data *pd, int off)
1651 struct cfq_group *cfqg = pd_to_cfqg(pd);
1653 if (!cfqg->dev_leaf_weight)
1655 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1658 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1660 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1661 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1666 static int cfq_print_weight(struct seq_file *sf, void *v)
1668 seq_printf(sf, "%u\n", css_to_blkcg(seq_css(sf))->cfq_weight);
1672 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1674 seq_printf(sf, "%u\n", css_to_blkcg(seq_css(sf))->cfq_leaf_weight);
1678 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1679 char *buf, size_t nbytes, loff_t off,
1680 bool is_leaf_weight)
1682 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1683 struct blkg_conf_ctx ctx;
1684 struct cfq_group *cfqg;
1687 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1692 cfqg = blkg_to_cfqg(ctx.blkg);
1693 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1694 if (!is_leaf_weight) {
1695 cfqg->dev_weight = ctx.v;
1696 cfqg->new_weight = ctx.v ?: blkcg->cfq_weight;
1698 cfqg->dev_leaf_weight = ctx.v;
1699 cfqg->new_leaf_weight = ctx.v ?: blkcg->cfq_leaf_weight;
1704 blkg_conf_finish(&ctx);
1705 return ret ?: nbytes;
1708 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1709 char *buf, size_t nbytes, loff_t off)
1711 return __cfqg_set_weight_device(of, buf, nbytes, off, false);
1714 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1715 char *buf, size_t nbytes, loff_t off)
1717 return __cfqg_set_weight_device(of, buf, nbytes, off, true);
1720 static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1721 u64 val, bool is_leaf_weight)
1723 struct blkcg *blkcg = css_to_blkcg(css);
1724 struct blkcg_gq *blkg;
1726 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1729 spin_lock_irq(&blkcg->lock);
1731 if (!is_leaf_weight)
1732 blkcg->cfq_weight = val;
1734 blkcg->cfq_leaf_weight = val;
1736 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1737 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1742 if (!is_leaf_weight) {
1743 if (!cfqg->dev_weight)
1744 cfqg->new_weight = blkcg->cfq_weight;
1746 if (!cfqg->dev_leaf_weight)
1747 cfqg->new_leaf_weight = blkcg->cfq_leaf_weight;
1751 spin_unlock_irq(&blkcg->lock);
1755 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1758 return __cfq_set_weight(css, cft, val, false);
1761 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1762 struct cftype *cft, u64 val)
1764 return __cfq_set_weight(css, cft, val, true);
1767 static int cfqg_print_stat(struct seq_file *sf, void *v)
1769 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1770 &blkcg_policy_cfq, seq_cft(sf)->private, false);
1774 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1776 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1777 &blkcg_policy_cfq, seq_cft(sf)->private, true);
1781 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1782 struct blkg_policy_data *pd, int off)
1784 u64 sum = cfqg_stat_pd_recursive_sum(pd, off);
1786 return __blkg_prfill_u64(sf, pd, sum);
1789 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1790 struct blkg_policy_data *pd, int off)
1792 struct blkg_rwstat sum = cfqg_rwstat_pd_recursive_sum(pd, off);
1794 return __blkg_prfill_rwstat(sf, pd, &sum);
1797 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1799 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1800 cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1801 seq_cft(sf)->private, false);
1805 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1807 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1808 cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1809 seq_cft(sf)->private, true);
1813 #ifdef CONFIG_DEBUG_BLK_CGROUP
1814 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1815 struct blkg_policy_data *pd, int off)
1817 struct cfq_group *cfqg = pd_to_cfqg(pd);
1818 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1822 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1823 v = div64_u64(v, samples);
1825 __blkg_prfill_u64(sf, pd, v);
1829 /* print avg_queue_size */
1830 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1832 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1833 cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1837 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1839 static struct cftype cfq_blkcg_files[] = {
1840 /* on root, weight is mapped to leaf_weight */
1842 .name = "weight_device",
1843 .flags = CFTYPE_ONLY_ON_ROOT,
1844 .seq_show = cfqg_print_leaf_weight_device,
1845 .write = cfqg_set_leaf_weight_device,
1849 .flags = CFTYPE_ONLY_ON_ROOT,
1850 .seq_show = cfq_print_leaf_weight,
1851 .write_u64 = cfq_set_leaf_weight,
1854 /* no such mapping necessary for !roots */
1856 .name = "weight_device",
1857 .flags = CFTYPE_NOT_ON_ROOT,
1858 .seq_show = cfqg_print_weight_device,
1859 .write = cfqg_set_weight_device,
1863 .flags = CFTYPE_NOT_ON_ROOT,
1864 .seq_show = cfq_print_weight,
1865 .write_u64 = cfq_set_weight,
1869 .name = "leaf_weight_device",
1870 .seq_show = cfqg_print_leaf_weight_device,
1871 .write = cfqg_set_leaf_weight_device,
1874 .name = "leaf_weight",
1875 .seq_show = cfq_print_leaf_weight,
1876 .write_u64 = cfq_set_leaf_weight,
1879 /* statistics, covers only the tasks in the cfqg */
1882 .private = offsetof(struct cfq_group, stats.time),
1883 .seq_show = cfqg_print_stat,
1887 .private = offsetof(struct cfq_group, stats.sectors),
1888 .seq_show = cfqg_print_stat,
1891 .name = "io_service_bytes",
1892 .private = offsetof(struct cfq_group, stats.service_bytes),
1893 .seq_show = cfqg_print_rwstat,
1896 .name = "io_serviced",
1897 .private = offsetof(struct cfq_group, stats.serviced),
1898 .seq_show = cfqg_print_rwstat,
1901 .name = "io_service_time",
1902 .private = offsetof(struct cfq_group, stats.service_time),
1903 .seq_show = cfqg_print_rwstat,
1906 .name = "io_wait_time",
1907 .private = offsetof(struct cfq_group, stats.wait_time),
1908 .seq_show = cfqg_print_rwstat,
1911 .name = "io_merged",
1912 .private = offsetof(struct cfq_group, stats.merged),
1913 .seq_show = cfqg_print_rwstat,
1916 .name = "io_queued",
1917 .private = offsetof(struct cfq_group, stats.queued),
1918 .seq_show = cfqg_print_rwstat,
1921 /* the same statictics which cover the cfqg and its descendants */
1923 .name = "time_recursive",
1924 .private = offsetof(struct cfq_group, stats.time),
1925 .seq_show = cfqg_print_stat_recursive,
1928 .name = "sectors_recursive",
1929 .private = offsetof(struct cfq_group, stats.sectors),
1930 .seq_show = cfqg_print_stat_recursive,
1933 .name = "io_service_bytes_recursive",
1934 .private = offsetof(struct cfq_group, stats.service_bytes),
1935 .seq_show = cfqg_print_rwstat_recursive,
1938 .name = "io_serviced_recursive",
1939 .private = offsetof(struct cfq_group, stats.serviced),
1940 .seq_show = cfqg_print_rwstat_recursive,
1943 .name = "io_service_time_recursive",
1944 .private = offsetof(struct cfq_group, stats.service_time),
1945 .seq_show = cfqg_print_rwstat_recursive,
1948 .name = "io_wait_time_recursive",
1949 .private = offsetof(struct cfq_group, stats.wait_time),
1950 .seq_show = cfqg_print_rwstat_recursive,
1953 .name = "io_merged_recursive",
1954 .private = offsetof(struct cfq_group, stats.merged),
1955 .seq_show = cfqg_print_rwstat_recursive,
1958 .name = "io_queued_recursive",
1959 .private = offsetof(struct cfq_group, stats.queued),
1960 .seq_show = cfqg_print_rwstat_recursive,
1962 #ifdef CONFIG_DEBUG_BLK_CGROUP
1964 .name = "avg_queue_size",
1965 .seq_show = cfqg_print_avg_queue_size,
1968 .name = "group_wait_time",
1969 .private = offsetof(struct cfq_group, stats.group_wait_time),
1970 .seq_show = cfqg_print_stat,
1973 .name = "idle_time",
1974 .private = offsetof(struct cfq_group, stats.idle_time),
1975 .seq_show = cfqg_print_stat,
1978 .name = "empty_time",
1979 .private = offsetof(struct cfq_group, stats.empty_time),
1980 .seq_show = cfqg_print_stat,
1984 .private = offsetof(struct cfq_group, stats.dequeue),
1985 .seq_show = cfqg_print_stat,
1988 .name = "unaccounted_time",
1989 .private = offsetof(struct cfq_group, stats.unaccounted_time),
1990 .seq_show = cfqg_print_stat,
1992 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1995 #else /* GROUP_IOSCHED */
1996 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1997 struct blkcg *blkcg)
1999 return cfqd->root_group;
2003 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2007 #endif /* GROUP_IOSCHED */
2010 * The cfqd->service_trees holds all pending cfq_queue's that have
2011 * requests waiting to be processed. It is sorted in the order that
2012 * we will service the queues.
2014 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2017 struct rb_node **p, *parent;
2018 struct cfq_queue *__cfqq;
2019 unsigned long rb_key;
2020 struct cfq_rb_root *st;
2024 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2025 if (cfq_class_idle(cfqq)) {
2026 rb_key = CFQ_IDLE_DELAY;
2027 parent = rb_last(&st->rb);
2028 if (parent && parent != &cfqq->rb_node) {
2029 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2030 rb_key += __cfqq->rb_key;
2033 } else if (!add_front) {
2035 * Get our rb key offset. Subtract any residual slice
2036 * value carried from last service. A negative resid
2037 * count indicates slice overrun, and this should position
2038 * the next service time further away in the tree.
2040 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
2041 rb_key -= cfqq->slice_resid;
2042 cfqq->slice_resid = 0;
2045 __cfqq = cfq_rb_first(st);
2046 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
2049 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2052 * same position, nothing more to do
2054 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2057 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2058 cfqq->service_tree = NULL;
2063 cfqq->service_tree = st;
2064 p = &st->rb.rb_node;
2067 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2070 * sort by key, that represents service time.
2072 if (time_before(rb_key, __cfqq->rb_key))
2073 p = &parent->rb_left;
2075 p = &parent->rb_right;
2081 st->left = &cfqq->rb_node;
2083 cfqq->rb_key = rb_key;
2084 rb_link_node(&cfqq->rb_node, parent, p);
2085 rb_insert_color(&cfqq->rb_node, &st->rb);
2087 if (add_front || !new_cfqq)
2089 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2092 static struct cfq_queue *
2093 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2094 sector_t sector, struct rb_node **ret_parent,
2095 struct rb_node ***rb_link)
2097 struct rb_node **p, *parent;
2098 struct cfq_queue *cfqq = NULL;
2106 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2109 * Sort strictly based on sector. Smallest to the left,
2110 * largest to the right.
2112 if (sector > blk_rq_pos(cfqq->next_rq))
2113 n = &(*p)->rb_right;
2114 else if (sector < blk_rq_pos(cfqq->next_rq))
2122 *ret_parent = parent;
2128 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2130 struct rb_node **p, *parent;
2131 struct cfq_queue *__cfqq;
2134 rb_erase(&cfqq->p_node, cfqq->p_root);
2135 cfqq->p_root = NULL;
2138 if (cfq_class_idle(cfqq))
2143 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2144 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2145 blk_rq_pos(cfqq->next_rq), &parent, &p);
2147 rb_link_node(&cfqq->p_node, parent, p);
2148 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2150 cfqq->p_root = NULL;
2154 * Update cfqq's position in the service tree.
2156 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2159 * Resorting requires the cfqq to be on the RR list already.
2161 if (cfq_cfqq_on_rr(cfqq)) {
2162 cfq_service_tree_add(cfqd, cfqq, 0);
2163 cfq_prio_tree_add(cfqd, cfqq);
2168 * add to busy list of queues for service, trying to be fair in ordering
2169 * the pending list according to last request service
2171 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2173 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2174 BUG_ON(cfq_cfqq_on_rr(cfqq));
2175 cfq_mark_cfqq_on_rr(cfqq);
2176 cfqd->busy_queues++;
2177 if (cfq_cfqq_sync(cfqq))
2178 cfqd->busy_sync_queues++;
2180 cfq_resort_rr_list(cfqd, cfqq);
2184 * Called when the cfqq no longer has requests pending, remove it from
2187 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2189 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2190 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2191 cfq_clear_cfqq_on_rr(cfqq);
2193 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2194 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2195 cfqq->service_tree = NULL;
2198 rb_erase(&cfqq->p_node, cfqq->p_root);
2199 cfqq->p_root = NULL;
2202 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2203 BUG_ON(!cfqd->busy_queues);
2204 cfqd->busy_queues--;
2205 if (cfq_cfqq_sync(cfqq))
2206 cfqd->busy_sync_queues--;
2210 * rb tree support functions
2212 static void cfq_del_rq_rb(struct request *rq)
2214 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2215 const int sync = rq_is_sync(rq);
2217 BUG_ON(!cfqq->queued[sync]);
2218 cfqq->queued[sync]--;
2220 elv_rb_del(&cfqq->sort_list, rq);
2222 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2224 * Queue will be deleted from service tree when we actually
2225 * expire it later. Right now just remove it from prio tree
2229 rb_erase(&cfqq->p_node, cfqq->p_root);
2230 cfqq->p_root = NULL;
2235 static void cfq_add_rq_rb(struct request *rq)
2237 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2238 struct cfq_data *cfqd = cfqq->cfqd;
2239 struct request *prev;
2241 cfqq->queued[rq_is_sync(rq)]++;
2243 elv_rb_add(&cfqq->sort_list, rq);
2245 if (!cfq_cfqq_on_rr(cfqq))
2246 cfq_add_cfqq_rr(cfqd, cfqq);
2249 * check if this request is a better next-serve candidate
2251 prev = cfqq->next_rq;
2252 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2255 * adjust priority tree position, if ->next_rq changes
2257 if (prev != cfqq->next_rq)
2258 cfq_prio_tree_add(cfqd, cfqq);
2260 BUG_ON(!cfqq->next_rq);
2263 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2265 elv_rb_del(&cfqq->sort_list, rq);
2266 cfqq->queued[rq_is_sync(rq)]--;
2267 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2269 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2273 static struct request *
2274 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2276 struct task_struct *tsk = current;
2277 struct cfq_io_cq *cic;
2278 struct cfq_queue *cfqq;
2280 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2284 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2286 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2291 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2293 struct cfq_data *cfqd = q->elevator->elevator_data;
2295 cfqd->rq_in_driver++;
2296 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2297 cfqd->rq_in_driver);
2299 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2302 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2304 struct cfq_data *cfqd = q->elevator->elevator_data;
2306 WARN_ON(!cfqd->rq_in_driver);
2307 cfqd->rq_in_driver--;
2308 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2309 cfqd->rq_in_driver);
2312 static void cfq_remove_request(struct request *rq)
2314 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2316 if (cfqq->next_rq == rq)
2317 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2319 list_del_init(&rq->queuelist);
2322 cfqq->cfqd->rq_queued--;
2323 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2324 if (rq->cmd_flags & REQ_PRIO) {
2325 WARN_ON(!cfqq->prio_pending);
2326 cfqq->prio_pending--;
2330 static int cfq_merge(struct request_queue *q, struct request **req,
2333 struct cfq_data *cfqd = q->elevator->elevator_data;
2334 struct request *__rq;
2336 __rq = cfq_find_rq_fmerge(cfqd, bio);
2337 if (__rq && elv_rq_merge_ok(__rq, bio)) {
2339 return ELEVATOR_FRONT_MERGE;
2342 return ELEVATOR_NO_MERGE;
2345 static void cfq_merged_request(struct request_queue *q, struct request *req,
2348 if (type == ELEVATOR_FRONT_MERGE) {
2349 struct cfq_queue *cfqq = RQ_CFQQ(req);
2351 cfq_reposition_rq_rb(cfqq, req);
2355 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2358 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
2362 cfq_merged_requests(struct request_queue *q, struct request *rq,
2363 struct request *next)
2365 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2366 struct cfq_data *cfqd = q->elevator->elevator_data;
2369 * reposition in fifo if next is older than rq
2371 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2372 time_before(next->fifo_time, rq->fifo_time) &&
2373 cfqq == RQ_CFQQ(next)) {
2374 list_move(&rq->queuelist, &next->queuelist);
2375 rq->fifo_time = next->fifo_time;
2378 if (cfqq->next_rq == next)
2380 cfq_remove_request(next);
2381 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2383 cfqq = RQ_CFQQ(next);
2385 * all requests of this queue are merged to other queues, delete it
2386 * from the service tree. If it's the active_queue,
2387 * cfq_dispatch_requests() will choose to expire it or do idle
2389 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2390 cfqq != cfqd->active_queue)
2391 cfq_del_cfqq_rr(cfqd, cfqq);
2394 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
2397 struct cfq_data *cfqd = q->elevator->elevator_data;
2398 struct cfq_io_cq *cic;
2399 struct cfq_queue *cfqq;
2402 * Disallow merge of a sync bio into an async request.
2404 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2408 * Lookup the cfqq that this bio will be queued with and allow
2409 * merge only if rq is queued there.
2411 cic = cfq_cic_lookup(cfqd, current->io_context);
2415 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2416 return cfqq == RQ_CFQQ(rq);
2419 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2421 del_timer(&cfqd->idle_slice_timer);
2422 cfqg_stats_update_idle_time(cfqq->cfqg);
2425 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2426 struct cfq_queue *cfqq)
2429 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2430 cfqd->serving_wl_class, cfqd->serving_wl_type);
2431 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2432 cfqq->slice_start = 0;
2433 cfqq->dispatch_start = jiffies;
2434 cfqq->allocated_slice = 0;
2435 cfqq->slice_end = 0;
2436 cfqq->slice_dispatch = 0;
2437 cfqq->nr_sectors = 0;
2439 cfq_clear_cfqq_wait_request(cfqq);
2440 cfq_clear_cfqq_must_dispatch(cfqq);
2441 cfq_clear_cfqq_must_alloc_slice(cfqq);
2442 cfq_clear_cfqq_fifo_expire(cfqq);
2443 cfq_mark_cfqq_slice_new(cfqq);
2445 cfq_del_timer(cfqd, cfqq);
2448 cfqd->active_queue = cfqq;
2452 * current cfqq expired its slice (or was too idle), select new one
2455 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2458 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2460 if (cfq_cfqq_wait_request(cfqq))
2461 cfq_del_timer(cfqd, cfqq);
2463 cfq_clear_cfqq_wait_request(cfqq);
2464 cfq_clear_cfqq_wait_busy(cfqq);
2467 * If this cfqq is shared between multiple processes, check to
2468 * make sure that those processes are still issuing I/Os within
2469 * the mean seek distance. If not, it may be time to break the
2470 * queues apart again.
2472 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2473 cfq_mark_cfqq_split_coop(cfqq);
2476 * store what was left of this slice, if the queue idled/timed out
2479 if (cfq_cfqq_slice_new(cfqq))
2480 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2482 cfqq->slice_resid = cfqq->slice_end - jiffies;
2483 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2486 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2488 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2489 cfq_del_cfqq_rr(cfqd, cfqq);
2491 cfq_resort_rr_list(cfqd, cfqq);
2493 if (cfqq == cfqd->active_queue)
2494 cfqd->active_queue = NULL;
2496 if (cfqd->active_cic) {
2497 put_io_context(cfqd->active_cic->icq.ioc);
2498 cfqd->active_cic = NULL;
2502 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2504 struct cfq_queue *cfqq = cfqd->active_queue;
2507 __cfq_slice_expired(cfqd, cfqq, timed_out);
2511 * Get next queue for service. Unless we have a queue preemption,
2512 * we'll simply select the first cfqq in the service tree.
2514 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2516 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2517 cfqd->serving_wl_class, cfqd->serving_wl_type);
2519 if (!cfqd->rq_queued)
2522 /* There is nothing to dispatch */
2525 if (RB_EMPTY_ROOT(&st->rb))
2527 return cfq_rb_first(st);
2530 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2532 struct cfq_group *cfqg;
2533 struct cfq_queue *cfqq;
2535 struct cfq_rb_root *st;
2537 if (!cfqd->rq_queued)
2540 cfqg = cfq_get_next_cfqg(cfqd);
2544 for_each_cfqg_st(cfqg, i, j, st)
2545 if ((cfqq = cfq_rb_first(st)) != NULL)
2551 * Get and set a new active queue for service.
2553 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2554 struct cfq_queue *cfqq)
2557 cfqq = cfq_get_next_queue(cfqd);
2559 __cfq_set_active_queue(cfqd, cfqq);
2563 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2566 if (blk_rq_pos(rq) >= cfqd->last_position)
2567 return blk_rq_pos(rq) - cfqd->last_position;
2569 return cfqd->last_position - blk_rq_pos(rq);
2572 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2575 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2578 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2579 struct cfq_queue *cur_cfqq)
2581 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2582 struct rb_node *parent, *node;
2583 struct cfq_queue *__cfqq;
2584 sector_t sector = cfqd->last_position;
2586 if (RB_EMPTY_ROOT(root))
2590 * First, if we find a request starting at the end of the last
2591 * request, choose it.
2593 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2598 * If the exact sector wasn't found, the parent of the NULL leaf
2599 * will contain the closest sector.
2601 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2602 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2605 if (blk_rq_pos(__cfqq->next_rq) < sector)
2606 node = rb_next(&__cfqq->p_node);
2608 node = rb_prev(&__cfqq->p_node);
2612 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2613 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2621 * cur_cfqq - passed in so that we don't decide that the current queue is
2622 * closely cooperating with itself.
2624 * So, basically we're assuming that that cur_cfqq has dispatched at least
2625 * one request, and that cfqd->last_position reflects a position on the disk
2626 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2629 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2630 struct cfq_queue *cur_cfqq)
2632 struct cfq_queue *cfqq;
2634 if (cfq_class_idle(cur_cfqq))
2636 if (!cfq_cfqq_sync(cur_cfqq))
2638 if (CFQQ_SEEKY(cur_cfqq))
2642 * Don't search priority tree if it's the only queue in the group.
2644 if (cur_cfqq->cfqg->nr_cfqq == 1)
2648 * We should notice if some of the queues are cooperating, eg
2649 * working closely on the same area of the disk. In that case,
2650 * we can group them together and don't waste time idling.
2652 cfqq = cfqq_close(cfqd, cur_cfqq);
2656 /* If new queue belongs to different cfq_group, don't choose it */
2657 if (cur_cfqq->cfqg != cfqq->cfqg)
2661 * It only makes sense to merge sync queues.
2663 if (!cfq_cfqq_sync(cfqq))
2665 if (CFQQ_SEEKY(cfqq))
2669 * Do not merge queues of different priority classes
2671 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2678 * Determine whether we should enforce idle window for this queue.
2681 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2683 enum wl_class_t wl_class = cfqq_class(cfqq);
2684 struct cfq_rb_root *st = cfqq->service_tree;
2689 if (!cfqd->cfq_slice_idle)
2692 /* We never do for idle class queues. */
2693 if (wl_class == IDLE_WORKLOAD)
2696 /* We do for queues that were marked with idle window flag. */
2697 if (cfq_cfqq_idle_window(cfqq) &&
2698 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2702 * Otherwise, we do only if they are the last ones
2703 * in their service tree.
2705 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2706 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2708 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2712 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2714 struct cfq_queue *cfqq = cfqd->active_queue;
2715 struct cfq_io_cq *cic;
2716 unsigned long sl, group_idle = 0;
2719 * SSD device without seek penalty, disable idling. But only do so
2720 * for devices that support queuing, otherwise we still have a problem
2721 * with sync vs async workloads.
2723 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2726 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2727 WARN_ON(cfq_cfqq_slice_new(cfqq));
2730 * idle is disabled, either manually or by past process history
2732 if (!cfq_should_idle(cfqd, cfqq)) {
2733 /* no queue idling. Check for group idling */
2734 if (cfqd->cfq_group_idle)
2735 group_idle = cfqd->cfq_group_idle;
2741 * still active requests from this queue, don't idle
2743 if (cfqq->dispatched)
2747 * task has exited, don't wait
2749 cic = cfqd->active_cic;
2750 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2754 * If our average think time is larger than the remaining time
2755 * slice, then don't idle. This avoids overrunning the allotted
2758 if (sample_valid(cic->ttime.ttime_samples) &&
2759 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2760 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2761 cic->ttime.ttime_mean);
2765 /* There are other queues in the group, don't do group idle */
2766 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2769 cfq_mark_cfqq_wait_request(cfqq);
2772 sl = cfqd->cfq_group_idle;
2774 sl = cfqd->cfq_slice_idle;
2776 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2777 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2778 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2779 group_idle ? 1 : 0);
2783 * Move request from internal lists to the request queue dispatch list.
2785 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2787 struct cfq_data *cfqd = q->elevator->elevator_data;
2788 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2790 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2792 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2793 cfq_remove_request(rq);
2795 (RQ_CFQG(rq))->dispatched++;
2796 elv_dispatch_sort(q, rq);
2798 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2799 cfqq->nr_sectors += blk_rq_sectors(rq);
2800 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2804 * return expired entry, or NULL to just start from scratch in rbtree
2806 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2808 struct request *rq = NULL;
2810 if (cfq_cfqq_fifo_expire(cfqq))
2813 cfq_mark_cfqq_fifo_expire(cfqq);
2815 if (list_empty(&cfqq->fifo))
2818 rq = rq_entry_fifo(cfqq->fifo.next);
2819 if (time_before(jiffies, rq->fifo_time))
2822 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2827 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2829 const int base_rq = cfqd->cfq_slice_async_rq;
2831 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2833 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2837 * Must be called with the queue_lock held.
2839 static int cfqq_process_refs(struct cfq_queue *cfqq)
2841 int process_refs, io_refs;
2843 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2844 process_refs = cfqq->ref - io_refs;
2845 BUG_ON(process_refs < 0);
2846 return process_refs;
2849 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2851 int process_refs, new_process_refs;
2852 struct cfq_queue *__cfqq;
2855 * If there are no process references on the new_cfqq, then it is
2856 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2857 * chain may have dropped their last reference (not just their
2858 * last process reference).
2860 if (!cfqq_process_refs(new_cfqq))
2863 /* Avoid a circular list and skip interim queue merges */
2864 while ((__cfqq = new_cfqq->new_cfqq)) {
2870 process_refs = cfqq_process_refs(cfqq);
2871 new_process_refs = cfqq_process_refs(new_cfqq);
2873 * If the process for the cfqq has gone away, there is no
2874 * sense in merging the queues.
2876 if (process_refs == 0 || new_process_refs == 0)
2880 * Merge in the direction of the lesser amount of work.
2882 if (new_process_refs >= process_refs) {
2883 cfqq->new_cfqq = new_cfqq;
2884 new_cfqq->ref += process_refs;
2886 new_cfqq->new_cfqq = cfqq;
2887 cfqq->ref += new_process_refs;
2891 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2892 struct cfq_group *cfqg, enum wl_class_t wl_class)
2894 struct cfq_queue *queue;
2896 bool key_valid = false;
2897 unsigned long lowest_key = 0;
2898 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2900 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2901 /* select the one with lowest rb_key */
2902 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
2904 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2905 lowest_key = queue->rb_key;
2915 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
2919 struct cfq_rb_root *st;
2920 unsigned group_slice;
2921 enum wl_class_t original_class = cfqd->serving_wl_class;
2923 /* Choose next priority. RT > BE > IDLE */
2924 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2925 cfqd->serving_wl_class = RT_WORKLOAD;
2926 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2927 cfqd->serving_wl_class = BE_WORKLOAD;
2929 cfqd->serving_wl_class = IDLE_WORKLOAD;
2930 cfqd->workload_expires = jiffies + 1;
2934 if (original_class != cfqd->serving_wl_class)
2938 * For RT and BE, we have to choose also the type
2939 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2942 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2946 * check workload expiration, and that we still have other queues ready
2948 if (count && !time_after(jiffies, cfqd->workload_expires))
2952 /* otherwise select new workload type */
2953 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
2954 cfqd->serving_wl_class);
2955 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2959 * the workload slice is computed as a fraction of target latency
2960 * proportional to the number of queues in that workload, over
2961 * all the queues in the same priority class
2963 group_slice = cfq_group_slice(cfqd, cfqg);
2965 slice = group_slice * count /
2966 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
2967 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
2970 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
2974 * Async queues are currently system wide. Just taking
2975 * proportion of queues with-in same group will lead to higher
2976 * async ratio system wide as generally root group is going
2977 * to have higher weight. A more accurate thing would be to
2978 * calculate system wide asnc/sync ratio.
2980 tmp = cfqd->cfq_target_latency *
2981 cfqg_busy_async_queues(cfqd, cfqg);
2982 tmp = tmp/cfqd->busy_queues;
2983 slice = min_t(unsigned, slice, tmp);
2985 /* async workload slice is scaled down according to
2986 * the sync/async slice ratio. */
2987 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2989 /* sync workload slice is at least 2 * cfq_slice_idle */
2990 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2992 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2993 cfq_log(cfqd, "workload slice:%d", slice);
2994 cfqd->workload_expires = jiffies + slice;
2997 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2999 struct cfq_rb_root *st = &cfqd->grp_service_tree;
3000 struct cfq_group *cfqg;
3002 if (RB_EMPTY_ROOT(&st->rb))
3004 cfqg = cfq_rb_first_group(st);
3005 update_min_vdisktime(st);
3009 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3011 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3013 cfqd->serving_group = cfqg;
3015 /* Restore the workload type data */
3016 if (cfqg->saved_wl_slice) {
3017 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
3018 cfqd->serving_wl_type = cfqg->saved_wl_type;
3019 cfqd->serving_wl_class = cfqg->saved_wl_class;
3021 cfqd->workload_expires = jiffies - 1;
3023 choose_wl_class_and_type(cfqd, cfqg);
3027 * Select a queue for service. If we have a current active queue,
3028 * check whether to continue servicing it, or retrieve and set a new one.
3030 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3032 struct cfq_queue *cfqq, *new_cfqq = NULL;
3034 cfqq = cfqd->active_queue;
3038 if (!cfqd->rq_queued)
3042 * We were waiting for group to get backlogged. Expire the queue
3044 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3048 * The active queue has run out of time, expire it and select new.
3050 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3052 * If slice had not expired at the completion of last request
3053 * we might not have turned on wait_busy flag. Don't expire
3054 * the queue yet. Allow the group to get backlogged.
3056 * The very fact that we have used the slice, that means we
3057 * have been idling all along on this queue and it should be
3058 * ok to wait for this request to complete.
3060 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3061 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3065 goto check_group_idle;
3069 * The active queue has requests and isn't expired, allow it to
3072 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3076 * If another queue has a request waiting within our mean seek
3077 * distance, let it run. The expire code will check for close
3078 * cooperators and put the close queue at the front of the service
3079 * tree. If possible, merge the expiring queue with the new cfqq.
3081 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3083 if (!cfqq->new_cfqq)
3084 cfq_setup_merge(cfqq, new_cfqq);
3089 * No requests pending. If the active queue still has requests in
3090 * flight or is idling for a new request, allow either of these
3091 * conditions to happen (or time out) before selecting a new queue.
3093 if (timer_pending(&cfqd->idle_slice_timer)) {
3099 * This is a deep seek queue, but the device is much faster than
3100 * the queue can deliver, don't idle
3102 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3103 (cfq_cfqq_slice_new(cfqq) ||
3104 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
3105 cfq_clear_cfqq_deep(cfqq);
3106 cfq_clear_cfqq_idle_window(cfqq);
3109 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3115 * If group idle is enabled and there are requests dispatched from
3116 * this group, wait for requests to complete.
3119 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3120 cfqq->cfqg->dispatched &&
3121 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3127 cfq_slice_expired(cfqd, 0);
3130 * Current queue expired. Check if we have to switch to a new
3134 cfq_choose_cfqg(cfqd);
3136 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3141 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3145 while (cfqq->next_rq) {
3146 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3150 BUG_ON(!list_empty(&cfqq->fifo));
3152 /* By default cfqq is not expired if it is empty. Do it explicitly */
3153 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3158 * Drain our current requests. Used for barriers and when switching
3159 * io schedulers on-the-fly.
3161 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3163 struct cfq_queue *cfqq;
3166 /* Expire the timeslice of the current active queue first */
3167 cfq_slice_expired(cfqd, 0);
3168 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3169 __cfq_set_active_queue(cfqd, cfqq);
3170 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3173 BUG_ON(cfqd->busy_queues);
3175 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3179 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3180 struct cfq_queue *cfqq)
3182 /* the queue hasn't finished any request, can't estimate */
3183 if (cfq_cfqq_slice_new(cfqq))
3185 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
3192 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3194 unsigned int max_dispatch;
3197 * Drain async requests before we start sync IO
3199 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3203 * If this is an async queue and we have sync IO in flight, let it wait
3205 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3208 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3209 if (cfq_class_idle(cfqq))
3213 * Does this cfqq already have too much IO in flight?
3215 if (cfqq->dispatched >= max_dispatch) {
3216 bool promote_sync = false;
3218 * idle queue must always only have a single IO in flight
3220 if (cfq_class_idle(cfqq))
3224 * If there is only one sync queue
3225 * we can ignore async queue here and give the sync
3226 * queue no dispatch limit. The reason is a sync queue can
3227 * preempt async queue, limiting the sync queue doesn't make
3228 * sense. This is useful for aiostress test.
3230 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3231 promote_sync = true;
3234 * We have other queues, don't allow more IO from this one
3236 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3241 * Sole queue user, no limit
3243 if (cfqd->busy_queues == 1 || promote_sync)
3247 * Normally we start throttling cfqq when cfq_quantum/2
3248 * requests have been dispatched. But we can drive
3249 * deeper queue depths at the beginning of slice
3250 * subjected to upper limit of cfq_quantum.
3252 max_dispatch = cfqd->cfq_quantum;
3256 * Async queues must wait a bit before being allowed dispatch.
3257 * We also ramp up the dispatch depth gradually for async IO,
3258 * based on the last sync IO we serviced
3260 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3261 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
3264 depth = last_sync / cfqd->cfq_slice[1];
3265 if (!depth && !cfqq->dispatched)
3267 if (depth < max_dispatch)
3268 max_dispatch = depth;
3272 * If we're below the current max, allow a dispatch
3274 return cfqq->dispatched < max_dispatch;
3278 * Dispatch a request from cfqq, moving them to the request queue
3281 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3285 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3287 if (!cfq_may_dispatch(cfqd, cfqq))
3291 * follow expired path, else get first next available
3293 rq = cfq_check_fifo(cfqq);
3298 * insert request into driver dispatch list
3300 cfq_dispatch_insert(cfqd->queue, rq);
3302 if (!cfqd->active_cic) {
3303 struct cfq_io_cq *cic = RQ_CIC(rq);
3305 atomic_long_inc(&cic->icq.ioc->refcount);
3306 cfqd->active_cic = cic;
3313 * Find the cfqq that we need to service and move a request from that to the
3316 static int cfq_dispatch_requests(struct request_queue *q, int force)
3318 struct cfq_data *cfqd = q->elevator->elevator_data;
3319 struct cfq_queue *cfqq;
3321 if (!cfqd->busy_queues)
3324 if (unlikely(force))
3325 return cfq_forced_dispatch(cfqd);
3327 cfqq = cfq_select_queue(cfqd);
3332 * Dispatch a request from this cfqq, if it is allowed
3334 if (!cfq_dispatch_request(cfqd, cfqq))
3337 cfqq->slice_dispatch++;
3338 cfq_clear_cfqq_must_dispatch(cfqq);
3341 * expire an async queue immediately if it has used up its slice. idle
3342 * queue always expire after 1 dispatch round.
3344 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3345 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3346 cfq_class_idle(cfqq))) {
3347 cfqq->slice_end = jiffies + 1;
3348 cfq_slice_expired(cfqd, 0);
3351 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3356 * task holds one reference to the queue, dropped when task exits. each rq
3357 * in-flight on this queue also holds a reference, dropped when rq is freed.
3359 * Each cfq queue took a reference on the parent group. Drop it now.
3360 * queue lock must be held here.
3362 static void cfq_put_queue(struct cfq_queue *cfqq)
3364 struct cfq_data *cfqd = cfqq->cfqd;
3365 struct cfq_group *cfqg;
3367 BUG_ON(cfqq->ref <= 0);
3373 cfq_log_cfqq(cfqd, cfqq, "put_queue");
3374 BUG_ON(rb_first(&cfqq->sort_list));
3375 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3378 if (unlikely(cfqd->active_queue == cfqq)) {
3379 __cfq_slice_expired(cfqd, cfqq, 0);
3380 cfq_schedule_dispatch(cfqd);
3383 BUG_ON(cfq_cfqq_on_rr(cfqq));
3384 kmem_cache_free(cfq_pool, cfqq);
3388 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3390 struct cfq_queue *__cfqq, *next;
3393 * If this queue was scheduled to merge with another queue, be
3394 * sure to drop the reference taken on that queue (and others in
3395 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3397 __cfqq = cfqq->new_cfqq;
3399 if (__cfqq == cfqq) {
3400 WARN(1, "cfqq->new_cfqq loop detected\n");
3403 next = __cfqq->new_cfqq;
3404 cfq_put_queue(__cfqq);
3409 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3411 if (unlikely(cfqq == cfqd->active_queue)) {
3412 __cfq_slice_expired(cfqd, cfqq, 0);
3413 cfq_schedule_dispatch(cfqd);
3416 cfq_put_cooperator(cfqq);
3418 cfq_put_queue(cfqq);
3421 static void cfq_init_icq(struct io_cq *icq)
3423 struct cfq_io_cq *cic = icq_to_cic(icq);
3425 cic->ttime.last_end_request = jiffies;
3428 static void cfq_exit_icq(struct io_cq *icq)
3430 struct cfq_io_cq *cic = icq_to_cic(icq);
3431 struct cfq_data *cfqd = cic_to_cfqd(cic);
3433 if (cic->cfqq[BLK_RW_ASYNC]) {
3434 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3435 cic->cfqq[BLK_RW_ASYNC] = NULL;
3438 if (cic->cfqq[BLK_RW_SYNC]) {
3439 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3440 cic->cfqq[BLK_RW_SYNC] = NULL;
3444 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3446 struct task_struct *tsk = current;
3449 if (!cfq_cfqq_prio_changed(cfqq))
3452 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3453 switch (ioprio_class) {
3455 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3456 case IOPRIO_CLASS_NONE:
3458 * no prio set, inherit CPU scheduling settings
3460 cfqq->ioprio = task_nice_ioprio(tsk);
3461 cfqq->ioprio_class = task_nice_ioclass(tsk);
3463 case IOPRIO_CLASS_RT:
3464 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3465 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3467 case IOPRIO_CLASS_BE:
3468 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3469 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3471 case IOPRIO_CLASS_IDLE:
3472 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3474 cfq_clear_cfqq_idle_window(cfqq);
3479 * keep track of original prio settings in case we have to temporarily
3480 * elevate the priority of this queue
3482 cfqq->org_ioprio = cfqq->ioprio;
3483 cfq_clear_cfqq_prio_changed(cfqq);
3486 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3488 int ioprio = cic->icq.ioc->ioprio;
3489 struct cfq_data *cfqd = cic_to_cfqd(cic);
3490 struct cfq_queue *cfqq;
3493 * Check whether ioprio has changed. The condition may trigger
3494 * spuriously on a newly created cic but there's no harm.
3496 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3499 cfqq = cic->cfqq[BLK_RW_ASYNC];
3501 struct cfq_queue *new_cfqq;
3502 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3505 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3506 cfq_put_queue(cfqq);
3510 cfqq = cic->cfqq[BLK_RW_SYNC];
3512 cfq_mark_cfqq_prio_changed(cfqq);
3514 cic->ioprio = ioprio;
3517 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3518 pid_t pid, bool is_sync)
3520 RB_CLEAR_NODE(&cfqq->rb_node);
3521 RB_CLEAR_NODE(&cfqq->p_node);
3522 INIT_LIST_HEAD(&cfqq->fifo);
3527 cfq_mark_cfqq_prio_changed(cfqq);
3530 if (!cfq_class_idle(cfqq))
3531 cfq_mark_cfqq_idle_window(cfqq);
3532 cfq_mark_cfqq_sync(cfqq);
3537 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3538 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3540 struct cfq_data *cfqd = cic_to_cfqd(cic);
3541 struct cfq_queue *sync_cfqq;
3545 id = bio_blkcg(bio)->id;
3549 * Check whether blkcg has changed. The condition may trigger
3550 * spuriously on a newly created cic but there's no harm.
3552 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3555 sync_cfqq = cic_to_cfqq(cic, 1);
3558 * Drop reference to sync queue. A new sync queue will be
3559 * assigned in new group upon arrival of a fresh request.
3561 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3562 cic_set_cfqq(cic, NULL, 1);
3563 cfq_put_queue(sync_cfqq);
3569 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3570 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3572 static struct cfq_queue *
3573 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3574 struct bio *bio, gfp_t gfp_mask)
3576 struct blkcg *blkcg;
3577 struct cfq_queue *cfqq, *new_cfqq = NULL;
3578 struct cfq_group *cfqg;
3583 blkcg = bio_blkcg(bio);
3584 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3585 cfqq = cic_to_cfqq(cic, is_sync);
3588 * Always try a new alloc if we fell back to the OOM cfqq
3589 * originally, since it should just be a temporary situation.
3591 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3596 } else if (gfp_mask & __GFP_WAIT) {
3598 spin_unlock_irq(cfqd->queue->queue_lock);
3599 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3600 gfp_mask | __GFP_ZERO,
3602 spin_lock_irq(cfqd->queue->queue_lock);
3606 return &cfqd->oom_cfqq;
3608 cfqq = kmem_cache_alloc_node(cfq_pool,
3609 gfp_mask | __GFP_ZERO,
3614 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3615 cfq_init_prio_data(cfqq, cic);
3616 cfq_link_cfqq_cfqg(cfqq, cfqg);
3617 cfq_log_cfqq(cfqd, cfqq, "alloced");
3619 cfqq = &cfqd->oom_cfqq;
3623 kmem_cache_free(cfq_pool, new_cfqq);
3629 static struct cfq_queue **
3630 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3632 switch (ioprio_class) {
3633 case IOPRIO_CLASS_RT:
3634 return &cfqd->async_cfqq[0][ioprio];
3635 case IOPRIO_CLASS_NONE:
3636 ioprio = IOPRIO_NORM;
3638 case IOPRIO_CLASS_BE:
3639 return &cfqd->async_cfqq[1][ioprio];
3640 case IOPRIO_CLASS_IDLE:
3641 return &cfqd->async_idle_cfqq;
3647 static struct cfq_queue *
3648 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3649 struct bio *bio, gfp_t gfp_mask)
3651 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3652 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3653 struct cfq_queue **async_cfqq = NULL;
3654 struct cfq_queue *cfqq = NULL;
3657 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3662 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3665 * pin the queue now that it's allocated, scheduler exit will prune it
3667 if (!is_sync && !(*async_cfqq)) {
3677 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3679 unsigned long elapsed = jiffies - ttime->last_end_request;
3680 elapsed = min(elapsed, 2UL * slice_idle);
3682 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3683 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3684 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3688 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3689 struct cfq_io_cq *cic)
3691 if (cfq_cfqq_sync(cfqq)) {
3692 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3693 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3694 cfqd->cfq_slice_idle);
3696 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3697 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3702 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3706 sector_t n_sec = blk_rq_sectors(rq);
3707 if (cfqq->last_request_pos) {
3708 if (cfqq->last_request_pos < blk_rq_pos(rq))
3709 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3711 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3714 cfqq->seek_history <<= 1;
3715 if (blk_queue_nonrot(cfqd->queue))
3716 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3718 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3722 * Disable idle window if the process thinks too long or seeks so much that
3726 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3727 struct cfq_io_cq *cic)
3729 int old_idle, enable_idle;
3732 * Don't idle for async or idle io prio class
3734 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3737 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3739 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3740 cfq_mark_cfqq_deep(cfqq);
3742 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3744 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3745 !cfqd->cfq_slice_idle ||
3746 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3748 else if (sample_valid(cic->ttime.ttime_samples)) {
3749 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3755 if (old_idle != enable_idle) {
3756 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3758 cfq_mark_cfqq_idle_window(cfqq);
3760 cfq_clear_cfqq_idle_window(cfqq);
3765 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3766 * no or if we aren't sure, a 1 will cause a preempt.
3769 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3772 struct cfq_queue *cfqq;
3774 cfqq = cfqd->active_queue;
3778 if (cfq_class_idle(new_cfqq))
3781 if (cfq_class_idle(cfqq))
3785 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3787 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3791 * if the new request is sync, but the currently running queue is
3792 * not, let the sync request have priority.
3794 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3797 if (new_cfqq->cfqg != cfqq->cfqg)
3800 if (cfq_slice_used(cfqq))
3803 /* Allow preemption only if we are idling on sync-noidle tree */
3804 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3805 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3806 new_cfqq->service_tree->count == 2 &&
3807 RB_EMPTY_ROOT(&cfqq->sort_list))
3811 * So both queues are sync. Let the new request get disk time if
3812 * it's a metadata request and the current queue is doing regular IO.
3814 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3818 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3820 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3823 /* An idle queue should not be idle now for some reason */
3824 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3827 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3831 * if this request is as-good as one we would expect from the
3832 * current cfqq, let it preempt
3834 if (cfq_rq_close(cfqd, cfqq, rq))
3841 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3842 * let it have half of its nominal slice.
3844 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3846 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3848 cfq_log_cfqq(cfqd, cfqq, "preempt");
3849 cfq_slice_expired(cfqd, 1);
3852 * workload type is changed, don't save slice, otherwise preempt
3855 if (old_type != cfqq_type(cfqq))
3856 cfqq->cfqg->saved_wl_slice = 0;
3859 * Put the new queue at the front of the of the current list,
3860 * so we know that it will be selected next.
3862 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3864 cfq_service_tree_add(cfqd, cfqq, 1);
3866 cfqq->slice_end = 0;
3867 cfq_mark_cfqq_slice_new(cfqq);
3871 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3872 * something we should do about it
3875 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3878 struct cfq_io_cq *cic = RQ_CIC(rq);
3881 if (rq->cmd_flags & REQ_PRIO)
3882 cfqq->prio_pending++;
3884 cfq_update_io_thinktime(cfqd, cfqq, cic);
3885 cfq_update_io_seektime(cfqd, cfqq, rq);
3886 cfq_update_idle_window(cfqd, cfqq, cic);
3888 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3890 if (cfqq == cfqd->active_queue) {
3892 * Remember that we saw a request from this process, but
3893 * don't start queuing just yet. Otherwise we risk seeing lots
3894 * of tiny requests, because we disrupt the normal plugging
3895 * and merging. If the request is already larger than a single
3896 * page, let it rip immediately. For that case we assume that
3897 * merging is already done. Ditto for a busy system that
3898 * has other work pending, don't risk delaying until the
3899 * idle timer unplug to continue working.
3901 if (cfq_cfqq_wait_request(cfqq)) {
3902 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3903 cfqd->busy_queues > 1) {
3904 cfq_del_timer(cfqd, cfqq);
3905 cfq_clear_cfqq_wait_request(cfqq);
3906 __blk_run_queue(cfqd->queue);
3908 cfqg_stats_update_idle_time(cfqq->cfqg);
3909 cfq_mark_cfqq_must_dispatch(cfqq);
3912 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3914 * not the active queue - expire current slice if it is
3915 * idle and has expired it's mean thinktime or this new queue
3916 * has some old slice time left and is of higher priority or
3917 * this new queue is RT and the current one is BE
3919 cfq_preempt_queue(cfqd, cfqq);
3920 __blk_run_queue(cfqd->queue);
3924 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3926 struct cfq_data *cfqd = q->elevator->elevator_data;
3927 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3929 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3930 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3932 rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
3933 list_add_tail(&rq->queuelist, &cfqq->fifo);
3935 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3937 cfq_rq_enqueued(cfqd, cfqq, rq);
3941 * Update hw_tag based on peak queue depth over 50 samples under
3944 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3946 struct cfq_queue *cfqq = cfqd->active_queue;
3948 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3949 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3951 if (cfqd->hw_tag == 1)
3954 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3955 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3959 * If active queue hasn't enough requests and can idle, cfq might not
3960 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3963 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3964 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3965 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3968 if (cfqd->hw_tag_samples++ < 50)
3971 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3977 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3979 struct cfq_io_cq *cic = cfqd->active_cic;
3981 /* If the queue already has requests, don't wait */
3982 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3985 /* If there are other queues in the group, don't wait */
3986 if (cfqq->cfqg->nr_cfqq > 1)
3989 /* the only queue in the group, but think time is big */
3990 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3993 if (cfq_slice_used(cfqq))
3996 /* if slice left is less than think time, wait busy */
3997 if (cic && sample_valid(cic->ttime.ttime_samples)
3998 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
4002 * If think times is less than a jiffy than ttime_mean=0 and above
4003 * will not be true. It might happen that slice has not expired yet
4004 * but will expire soon (4-5 ns) during select_queue(). To cover the
4005 * case where think time is less than a jiffy, mark the queue wait
4006 * busy if only 1 jiffy is left in the slice.
4008 if (cfqq->slice_end - jiffies == 1)
4014 static void cfq_completed_request(struct request_queue *q, struct request *rq)
4016 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4017 struct cfq_data *cfqd = cfqq->cfqd;
4018 const int sync = rq_is_sync(rq);
4022 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4023 !!(rq->cmd_flags & REQ_NOIDLE));
4025 cfq_update_hw_tag(cfqd);
4027 WARN_ON(!cfqd->rq_in_driver);
4028 WARN_ON(!cfqq->dispatched);
4029 cfqd->rq_in_driver--;
4031 (RQ_CFQG(rq))->dispatched--;
4032 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4033 rq_io_start_time_ns(rq), rq->cmd_flags);
4035 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4038 struct cfq_rb_root *st;
4040 RQ_CIC(rq)->ttime.last_end_request = now;
4042 if (cfq_cfqq_on_rr(cfqq))
4043 st = cfqq->service_tree;
4045 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4048 st->ttime.last_end_request = now;
4049 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
4050 cfqd->last_delayed_sync = now;
4053 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4054 cfqq->cfqg->ttime.last_end_request = now;
4058 * If this is the active queue, check if it needs to be expired,
4059 * or if we want to idle in case it has no pending requests.
4061 if (cfqd->active_queue == cfqq) {
4062 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4064 if (cfq_cfqq_slice_new(cfqq)) {
4065 cfq_set_prio_slice(cfqd, cfqq);
4066 cfq_clear_cfqq_slice_new(cfqq);
4070 * Should we wait for next request to come in before we expire
4073 if (cfq_should_wait_busy(cfqd, cfqq)) {
4074 unsigned long extend_sl = cfqd->cfq_slice_idle;
4075 if (!cfqd->cfq_slice_idle)
4076 extend_sl = cfqd->cfq_group_idle;
4077 cfqq->slice_end = jiffies + extend_sl;
4078 cfq_mark_cfqq_wait_busy(cfqq);
4079 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4083 * Idling is not enabled on:
4085 * - idle-priority queues
4087 * - queues with still some requests queued
4088 * - when there is a close cooperator
4090 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4091 cfq_slice_expired(cfqd, 1);
4092 else if (sync && cfqq_empty &&
4093 !cfq_close_cooperator(cfqd, cfqq)) {
4094 cfq_arm_slice_timer(cfqd);
4098 if (!cfqd->rq_in_driver)
4099 cfq_schedule_dispatch(cfqd);
4102 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4104 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4105 cfq_mark_cfqq_must_alloc_slice(cfqq);
4106 return ELV_MQUEUE_MUST;
4109 return ELV_MQUEUE_MAY;
4112 static int cfq_may_queue(struct request_queue *q, int rw)
4114 struct cfq_data *cfqd = q->elevator->elevator_data;
4115 struct task_struct *tsk = current;
4116 struct cfq_io_cq *cic;
4117 struct cfq_queue *cfqq;
4120 * don't force setup of a queue from here, as a call to may_queue
4121 * does not necessarily imply that a request actually will be queued.
4122 * so just lookup a possibly existing queue, or return 'may queue'
4125 cic = cfq_cic_lookup(cfqd, tsk->io_context);
4127 return ELV_MQUEUE_MAY;
4129 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
4131 cfq_init_prio_data(cfqq, cic);
4133 return __cfq_may_queue(cfqq);
4136 return ELV_MQUEUE_MAY;
4140 * queue lock held here
4142 static void cfq_put_request(struct request *rq)
4144 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4147 const int rw = rq_data_dir(rq);
4149 BUG_ON(!cfqq->allocated[rw]);
4150 cfqq->allocated[rw]--;
4152 /* Put down rq reference on cfqg */
4153 cfqg_put(RQ_CFQG(rq));
4154 rq->elv.priv[0] = NULL;
4155 rq->elv.priv[1] = NULL;
4157 cfq_put_queue(cfqq);
4161 static struct cfq_queue *
4162 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4163 struct cfq_queue *cfqq)
4165 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4166 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4167 cfq_mark_cfqq_coop(cfqq->new_cfqq);
4168 cfq_put_queue(cfqq);
4169 return cic_to_cfqq(cic, 1);
4173 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4174 * was the last process referring to said cfqq.
4176 static struct cfq_queue *
4177 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4179 if (cfqq_process_refs(cfqq) == 1) {
4180 cfqq->pid = current->pid;
4181 cfq_clear_cfqq_coop(cfqq);
4182 cfq_clear_cfqq_split_coop(cfqq);
4186 cic_set_cfqq(cic, NULL, 1);
4188 cfq_put_cooperator(cfqq);
4190 cfq_put_queue(cfqq);
4194 * Allocate cfq data structures associated with this request.
4197 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4200 struct cfq_data *cfqd = q->elevator->elevator_data;
4201 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4202 const int rw = rq_data_dir(rq);
4203 const bool is_sync = rq_is_sync(rq);
4204 struct cfq_queue *cfqq;
4206 might_sleep_if(gfp_mask & __GFP_WAIT);
4208 spin_lock_irq(q->queue_lock);
4210 check_ioprio_changed(cic, bio);
4211 check_blkcg_changed(cic, bio);
4213 cfqq = cic_to_cfqq(cic, is_sync);
4214 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4215 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
4216 cic_set_cfqq(cic, cfqq, is_sync);
4219 * If the queue was seeky for too long, break it apart.
4221 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4222 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4223 cfqq = split_cfqq(cic, cfqq);
4229 * Check to see if this queue is scheduled to merge with
4230 * another, closely cooperating queue. The merging of
4231 * queues happens here as it must be done in process context.
4232 * The reference on new_cfqq was taken in merge_cfqqs.
4235 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4238 cfqq->allocated[rw]++;
4241 cfqg_get(cfqq->cfqg);
4242 rq->elv.priv[0] = cfqq;
4243 rq->elv.priv[1] = cfqq->cfqg;
4244 spin_unlock_irq(q->queue_lock);
4248 static void cfq_kick_queue(struct work_struct *work)
4250 struct cfq_data *cfqd =
4251 container_of(work, struct cfq_data, unplug_work);
4252 struct request_queue *q = cfqd->queue;
4254 spin_lock_irq(q->queue_lock);
4255 __blk_run_queue(cfqd->queue);
4256 spin_unlock_irq(q->queue_lock);
4260 * Timer running if the active_queue is currently idling inside its time slice
4262 static void cfq_idle_slice_timer(unsigned long data)
4264 struct cfq_data *cfqd = (struct cfq_data *) data;
4265 struct cfq_queue *cfqq;
4266 unsigned long flags;
4269 cfq_log(cfqd, "idle timer fired");
4271 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4273 cfqq = cfqd->active_queue;
4278 * We saw a request before the queue expired, let it through
4280 if (cfq_cfqq_must_dispatch(cfqq))
4286 if (cfq_slice_used(cfqq))
4290 * only expire and reinvoke request handler, if there are
4291 * other queues with pending requests
4293 if (!cfqd->busy_queues)
4297 * not expired and it has a request pending, let it dispatch
4299 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4303 * Queue depth flag is reset only when the idle didn't succeed
4305 cfq_clear_cfqq_deep(cfqq);
4308 cfq_slice_expired(cfqd, timed_out);
4310 cfq_schedule_dispatch(cfqd);
4312 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4315 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4317 del_timer_sync(&cfqd->idle_slice_timer);
4318 cancel_work_sync(&cfqd->unplug_work);
4321 static void cfq_put_async_queues(struct cfq_data *cfqd)
4325 for (i = 0; i < IOPRIO_BE_NR; i++) {
4326 if (cfqd->async_cfqq[0][i])
4327 cfq_put_queue(cfqd->async_cfqq[0][i]);
4328 if (cfqd->async_cfqq[1][i])
4329 cfq_put_queue(cfqd->async_cfqq[1][i]);
4332 if (cfqd->async_idle_cfqq)
4333 cfq_put_queue(cfqd->async_idle_cfqq);
4336 static void cfq_exit_queue(struct elevator_queue *e)
4338 struct cfq_data *cfqd = e->elevator_data;
4339 struct request_queue *q = cfqd->queue;
4341 cfq_shutdown_timer_wq(cfqd);
4343 spin_lock_irq(q->queue_lock);
4345 if (cfqd->active_queue)
4346 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4348 cfq_put_async_queues(cfqd);
4350 spin_unlock_irq(q->queue_lock);
4352 cfq_shutdown_timer_wq(cfqd);
4354 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4355 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4357 kfree(cfqd->root_group);
4362 static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4364 struct cfq_data *cfqd;
4365 struct blkcg_gq *blkg __maybe_unused;
4367 struct elevator_queue *eq;
4369 eq = elevator_alloc(q, e);
4373 cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4375 kobject_put(&eq->kobj);
4378 eq->elevator_data = cfqd;
4381 spin_lock_irq(q->queue_lock);
4383 spin_unlock_irq(q->queue_lock);
4385 /* Init root service tree */
4386 cfqd->grp_service_tree = CFQ_RB_ROOT;
4388 /* Init root group and prefer root group over other groups by default */
4389 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4390 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4394 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4397 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4398 GFP_KERNEL, cfqd->queue->node);
4399 if (!cfqd->root_group)
4402 cfq_init_cfqg_base(cfqd->root_group);
4404 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
4405 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
4408 * Not strictly needed (since RB_ROOT just clears the node and we
4409 * zeroed cfqd on alloc), but better be safe in case someone decides
4410 * to add magic to the rb code
4412 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4413 cfqd->prio_trees[i] = RB_ROOT;
4416 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4417 * Grab a permanent reference to it, so that the normal code flow
4418 * will not attempt to free it. oom_cfqq is linked to root_group
4419 * but shouldn't hold a reference as it'll never be unlinked. Lose
4420 * the reference from linking right away.
4422 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4423 cfqd->oom_cfqq.ref++;
4425 spin_lock_irq(q->queue_lock);
4426 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4427 cfqg_put(cfqd->root_group);
4428 spin_unlock_irq(q->queue_lock);
4430 init_timer(&cfqd->idle_slice_timer);
4431 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4432 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4434 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4436 cfqd->cfq_quantum = cfq_quantum;
4437 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4438 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4439 cfqd->cfq_back_max = cfq_back_max;
4440 cfqd->cfq_back_penalty = cfq_back_penalty;
4441 cfqd->cfq_slice[0] = cfq_slice_async;
4442 cfqd->cfq_slice[1] = cfq_slice_sync;
4443 cfqd->cfq_target_latency = cfq_target_latency;
4444 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4445 cfqd->cfq_slice_idle = cfq_slice_idle;
4446 cfqd->cfq_group_idle = cfq_group_idle;
4447 cfqd->cfq_latency = 1;
4450 * we optimistically start assuming sync ops weren't delayed in last
4451 * second, in order to have larger depth for async operations.
4453 cfqd->last_delayed_sync = jiffies - HZ;
4458 kobject_put(&eq->kobj);
4463 * sysfs parts below -->
4466 cfq_var_show(unsigned int var, char *page)
4468 return sprintf(page, "%u\n", var);
4472 cfq_var_store(unsigned int *var, const char *page, size_t count)
4474 char *p = (char *) page;
4476 *var = simple_strtoul(p, &p, 10);
4480 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4481 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4483 struct cfq_data *cfqd = e->elevator_data; \
4484 unsigned int __data = __VAR; \
4486 __data = jiffies_to_msecs(__data); \
4487 return cfq_var_show(__data, (page)); \
4489 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4490 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4491 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4492 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4493 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4494 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4495 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4496 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4497 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4498 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4499 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4500 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4501 #undef SHOW_FUNCTION
4503 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4504 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4506 struct cfq_data *cfqd = e->elevator_data; \
4507 unsigned int __data; \
4508 int ret = cfq_var_store(&__data, (page), count); \
4509 if (__data < (MIN)) \
4511 else if (__data > (MAX)) \
4514 *(__PTR) = msecs_to_jiffies(__data); \
4516 *(__PTR) = __data; \
4519 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4520 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4522 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4524 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4525 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4527 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4528 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4529 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4530 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4531 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4533 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4534 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4535 #undef STORE_FUNCTION
4537 #define CFQ_ATTR(name) \
4538 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4540 static struct elv_fs_entry cfq_attrs[] = {
4542 CFQ_ATTR(fifo_expire_sync),
4543 CFQ_ATTR(fifo_expire_async),
4544 CFQ_ATTR(back_seek_max),
4545 CFQ_ATTR(back_seek_penalty),
4546 CFQ_ATTR(slice_sync),
4547 CFQ_ATTR(slice_async),
4548 CFQ_ATTR(slice_async_rq),
4549 CFQ_ATTR(slice_idle),
4550 CFQ_ATTR(group_idle),
4551 CFQ_ATTR(low_latency),
4552 CFQ_ATTR(target_latency),
4556 static struct elevator_type iosched_cfq = {
4558 .elevator_merge_fn = cfq_merge,
4559 .elevator_merged_fn = cfq_merged_request,
4560 .elevator_merge_req_fn = cfq_merged_requests,
4561 .elevator_allow_merge_fn = cfq_allow_merge,
4562 .elevator_bio_merged_fn = cfq_bio_merged,
4563 .elevator_dispatch_fn = cfq_dispatch_requests,
4564 .elevator_add_req_fn = cfq_insert_request,
4565 .elevator_activate_req_fn = cfq_activate_request,
4566 .elevator_deactivate_req_fn = cfq_deactivate_request,
4567 .elevator_completed_req_fn = cfq_completed_request,
4568 .elevator_former_req_fn = elv_rb_former_request,
4569 .elevator_latter_req_fn = elv_rb_latter_request,
4570 .elevator_init_icq_fn = cfq_init_icq,
4571 .elevator_exit_icq_fn = cfq_exit_icq,
4572 .elevator_set_req_fn = cfq_set_request,
4573 .elevator_put_req_fn = cfq_put_request,
4574 .elevator_may_queue_fn = cfq_may_queue,
4575 .elevator_init_fn = cfq_init_queue,
4576 .elevator_exit_fn = cfq_exit_queue,
4578 .icq_size = sizeof(struct cfq_io_cq),
4579 .icq_align = __alignof__(struct cfq_io_cq),
4580 .elevator_attrs = cfq_attrs,
4581 .elevator_name = "cfq",
4582 .elevator_owner = THIS_MODULE,
4585 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4586 static struct blkcg_policy blkcg_policy_cfq = {
4587 .pd_size = sizeof(struct cfq_group),
4588 .cftypes = cfq_blkcg_files,
4590 .pd_init_fn = cfq_pd_init,
4591 .pd_offline_fn = cfq_pd_offline,
4592 .pd_reset_stats_fn = cfq_pd_reset_stats,
4596 static int __init cfq_init(void)
4601 * could be 0 on HZ < 1000 setups
4603 if (!cfq_slice_async)
4604 cfq_slice_async = 1;
4605 if (!cfq_slice_idle)
4608 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4609 if (!cfq_group_idle)
4612 ret = blkcg_policy_register(&blkcg_policy_cfq);
4620 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4624 ret = elv_register(&iosched_cfq);
4631 kmem_cache_destroy(cfq_pool);
4633 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4634 blkcg_policy_unregister(&blkcg_policy_cfq);
4639 static void __exit cfq_exit(void)
4641 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4642 blkcg_policy_unregister(&blkcg_policy_cfq);
4644 elv_unregister(&iosched_cfq);
4645 kmem_cache_destroy(cfq_pool);
4648 module_init(cfq_init);
4649 module_exit(cfq_exit);
4651 MODULE_AUTHOR("Jens Axboe");
4652 MODULE_LICENSE("GPL");
4653 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");