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"
20 static struct blkio_policy_type blkio_policy_cfq;
25 /* max queue in one round of service */
26 static const int cfq_quantum = 8;
27 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
28 /* maximum backwards seek, in KiB */
29 static const int cfq_back_max = 16 * 1024;
30 /* penalty of a backwards seek */
31 static const int cfq_back_penalty = 2;
32 static const int cfq_slice_sync = HZ / 10;
33 static int cfq_slice_async = HZ / 25;
34 static const int cfq_slice_async_rq = 2;
35 static int cfq_slice_idle = HZ / 125;
36 static int cfq_group_idle = HZ / 125;
37 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
38 static const int cfq_hist_divisor = 4;
41 * offset from end of service tree
43 #define CFQ_IDLE_DELAY (HZ / 5)
46 * below this threshold, we consider thinktime immediate
48 #define CFQ_MIN_TT (2)
50 #define CFQ_SLICE_SCALE (5)
51 #define CFQ_HW_QUEUE_MIN (5)
52 #define CFQ_SERVICE_SHIFT 12
54 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
55 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
56 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
57 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
59 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
60 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
61 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
63 static struct kmem_cache *cfq_pool;
65 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
66 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
67 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69 #define sample_valid(samples) ((samples) > 80)
70 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73 unsigned long last_end_request;
75 unsigned long ttime_total;
76 unsigned long ttime_samples;
77 unsigned long ttime_mean;
81 * Most of our rbtree usage is for sorting with min extraction, so
82 * if we cache the leftmost node we don't have to walk down the tree
83 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
84 * move this into the elevator for the rq sorting as well.
90 unsigned total_weight;
92 struct cfq_ttime ttime;
94 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
95 .ttime = {.last_end_request = jiffies,},}
98 * Per process-grouping structure
101 /* reference count */
103 /* various state flags, see below */
105 /* parent cfq_data */
106 struct cfq_data *cfqd;
107 /* service_tree member */
108 struct rb_node rb_node;
109 /* service_tree key */
110 unsigned long rb_key;
111 /* prio tree member */
112 struct rb_node p_node;
113 /* prio tree root we belong to, if any */
114 struct rb_root *p_root;
115 /* sorted list of pending requests */
116 struct rb_root sort_list;
117 /* if fifo isn't expired, next request to serve */
118 struct request *next_rq;
119 /* requests queued in sort_list */
121 /* currently allocated requests */
123 /* fifo list of requests in sort_list */
124 struct list_head fifo;
126 /* time when queue got scheduled in to dispatch first request. */
127 unsigned long dispatch_start;
128 unsigned int allocated_slice;
129 unsigned int slice_dispatch;
130 /* time when first request from queue completed and slice started. */
131 unsigned long slice_start;
132 unsigned long slice_end;
135 /* pending priority requests */
137 /* number of requests that are on the dispatch list or inside driver */
140 /* io prio of this group */
141 unsigned short ioprio, org_ioprio;
142 unsigned short ioprio_class;
147 sector_t last_request_pos;
149 struct cfq_rb_root *service_tree;
150 struct cfq_queue *new_cfqq;
151 struct cfq_group *cfqg;
152 /* Number of sectors dispatched from queue in single dispatch round */
153 unsigned long nr_sectors;
157 * First index in the service_trees.
158 * IDLE is handled separately, so it has negative index
168 * Second index in the service_trees.
172 SYNC_NOIDLE_WORKLOAD = 1,
177 #ifdef CONFIG_CFQ_GROUP_IOSCHED
178 /* total bytes transferred */
179 struct blkg_rwstat service_bytes;
180 /* total IOs serviced, post merge */
181 struct blkg_rwstat serviced;
182 /* number of ios merged */
183 struct blkg_rwstat merged;
184 /* total time spent on device in ns, may not be accurate w/ queueing */
185 struct blkg_rwstat service_time;
186 /* total time spent waiting in scheduler queue in ns */
187 struct blkg_rwstat wait_time;
188 /* number of IOs queued up */
189 struct blkg_rwstat queued;
190 /* total sectors transferred */
191 struct blkg_stat sectors;
192 /* total disk time and nr sectors dispatched by this group */
193 struct blkg_stat time;
194 #ifdef CONFIG_DEBUG_BLK_CGROUP
195 /* time not charged to this cgroup */
196 struct blkg_stat unaccounted_time;
197 /* sum of number of ios queued across all samples */
198 struct blkg_stat avg_queue_size_sum;
199 /* count of samples taken for average */
200 struct blkg_stat avg_queue_size_samples;
201 /* how many times this group has been removed from service tree */
202 struct blkg_stat dequeue;
203 /* total time spent waiting for it to be assigned a timeslice. */
204 struct blkg_stat group_wait_time;
205 /* time spent idling for this blkio_group */
206 struct blkg_stat idle_time;
207 /* total time with empty current active q with other requests queued */
208 struct blkg_stat empty_time;
209 /* fields after this shouldn't be cleared on stat reset */
210 uint64_t start_group_wait_time;
211 uint64_t start_idle_time;
212 uint64_t start_empty_time;
214 #endif /* CONFIG_DEBUG_BLK_CGROUP */
215 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
218 /* This is per cgroup per device grouping structure */
220 /* group service_tree member */
221 struct rb_node rb_node;
223 /* group service_tree key */
226 unsigned int new_weight;
227 unsigned int dev_weight;
229 /* number of cfqq currently on this group */
233 * Per group busy queues average. Useful for workload slice calc. We
234 * create the array for each prio class but at run time it is used
235 * only for RT and BE class and slot for IDLE class remains unused.
236 * This is primarily done to avoid confusion and a gcc warning.
238 unsigned int busy_queues_avg[CFQ_PRIO_NR];
240 * rr lists of queues with requests. We maintain service trees for
241 * RT and BE classes. These trees are subdivided in subclasses
242 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
243 * class there is no subclassification and all the cfq queues go on
244 * a single tree service_tree_idle.
245 * Counts are embedded in the cfq_rb_root
247 struct cfq_rb_root service_trees[2][3];
248 struct cfq_rb_root service_tree_idle;
250 unsigned long saved_workload_slice;
251 enum wl_type_t saved_workload;
252 enum wl_prio_t saved_serving_prio;
254 /* number of requests that are on the dispatch list or inside driver */
256 struct cfq_ttime ttime;
257 struct cfqg_stats stats;
261 struct io_cq icq; /* must be the first member */
262 struct cfq_queue *cfqq[2];
263 struct cfq_ttime ttime;
264 int ioprio; /* the current ioprio */
265 #ifdef CONFIG_CFQ_GROUP_IOSCHED
266 uint64_t blkcg_id; /* the current blkcg ID */
271 * Per block device queue structure
274 struct request_queue *queue;
275 /* Root service tree for cfq_groups */
276 struct cfq_rb_root grp_service_tree;
277 struct cfq_group *root_group;
280 * The priority currently being served
282 enum wl_prio_t serving_prio;
283 enum wl_type_t serving_type;
284 unsigned long workload_expires;
285 struct cfq_group *serving_group;
288 * Each priority tree is sorted by next_request position. These
289 * trees are used when determining if two or more queues are
290 * interleaving requests (see cfq_close_cooperator).
292 struct rb_root prio_trees[CFQ_PRIO_LISTS];
294 unsigned int busy_queues;
295 unsigned int busy_sync_queues;
301 * queue-depth detection
307 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
308 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
311 int hw_tag_est_depth;
312 unsigned int hw_tag_samples;
315 * idle window management
317 struct timer_list idle_slice_timer;
318 struct work_struct unplug_work;
320 struct cfq_queue *active_queue;
321 struct cfq_io_cq *active_cic;
324 * async queue for each priority case
326 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
327 struct cfq_queue *async_idle_cfqq;
329 sector_t last_position;
332 * tunables, see top of file
334 unsigned int cfq_quantum;
335 unsigned int cfq_fifo_expire[2];
336 unsigned int cfq_back_penalty;
337 unsigned int cfq_back_max;
338 unsigned int cfq_slice[2];
339 unsigned int cfq_slice_async_rq;
340 unsigned int cfq_slice_idle;
341 unsigned int cfq_group_idle;
342 unsigned int cfq_latency;
345 * Fallback dummy cfqq for extreme OOM conditions
347 struct cfq_queue oom_cfqq;
349 unsigned long last_delayed_sync;
352 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
354 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
361 if (prio == IDLE_WORKLOAD)
362 return &cfqg->service_tree_idle;
364 return &cfqg->service_trees[prio][type];
367 enum cfqq_state_flags {
368 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
369 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
370 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
371 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
372 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
373 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
374 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
375 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
376 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
377 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
378 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
379 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
380 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
383 #define CFQ_CFQQ_FNS(name) \
384 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
386 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
388 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
390 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
392 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
394 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
398 CFQ_CFQQ_FNS(wait_request);
399 CFQ_CFQQ_FNS(must_dispatch);
400 CFQ_CFQQ_FNS(must_alloc_slice);
401 CFQ_CFQQ_FNS(fifo_expire);
402 CFQ_CFQQ_FNS(idle_window);
403 CFQ_CFQQ_FNS(prio_changed);
404 CFQ_CFQQ_FNS(slice_new);
407 CFQ_CFQQ_FNS(split_coop);
409 CFQ_CFQQ_FNS(wait_busy);
412 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
414 /* cfqg stats flags */
415 enum cfqg_stats_flags {
416 CFQG_stats_waiting = 0,
421 #define CFQG_FLAG_FNS(name) \
422 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
424 stats->flags |= (1 << CFQG_stats_##name); \
426 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
428 stats->flags &= ~(1 << CFQG_stats_##name); \
430 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
432 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
435 CFQG_FLAG_FNS(waiting)
436 CFQG_FLAG_FNS(idling)
440 /* This should be called with the queue_lock held. */
441 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
443 unsigned long long now;
445 if (!cfqg_stats_waiting(stats))
449 if (time_after64(now, stats->start_group_wait_time))
450 blkg_stat_add(&stats->group_wait_time,
451 now - stats->start_group_wait_time);
452 cfqg_stats_clear_waiting(stats);
455 /* This should be called with the queue_lock held. */
456 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
457 struct cfq_group *curr_cfqg)
459 struct cfqg_stats *stats = &cfqg->stats;
461 if (cfqg_stats_waiting(stats))
463 if (cfqg == curr_cfqg)
465 stats->start_group_wait_time = sched_clock();
466 cfqg_stats_mark_waiting(stats);
469 /* This should be called with the queue_lock held. */
470 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
472 unsigned long long now;
474 if (!cfqg_stats_empty(stats))
478 if (time_after64(now, stats->start_empty_time))
479 blkg_stat_add(&stats->empty_time,
480 now - stats->start_empty_time);
481 cfqg_stats_clear_empty(stats);
484 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
486 blkg_stat_add(&cfqg->stats.dequeue, 1);
489 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
491 struct cfqg_stats *stats = &cfqg->stats;
493 if (blkg_rwstat_sum(&stats->queued))
497 * group is already marked empty. This can happen if cfqq got new
498 * request in parent group and moved to this group while being added
499 * to service tree. Just ignore the event and move on.
501 if (cfqg_stats_empty(stats))
504 stats->start_empty_time = sched_clock();
505 cfqg_stats_mark_empty(stats);
508 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
510 struct cfqg_stats *stats = &cfqg->stats;
512 if (cfqg_stats_idling(stats)) {
513 unsigned long long now = sched_clock();
515 if (time_after64(now, stats->start_idle_time))
516 blkg_stat_add(&stats->idle_time,
517 now - stats->start_idle_time);
518 cfqg_stats_clear_idling(stats);
522 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
524 struct cfqg_stats *stats = &cfqg->stats;
526 BUG_ON(cfqg_stats_idling(stats));
528 stats->start_idle_time = sched_clock();
529 cfqg_stats_mark_idling(stats);
532 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
534 struct cfqg_stats *stats = &cfqg->stats;
536 blkg_stat_add(&stats->avg_queue_size_sum,
537 blkg_rwstat_sum(&stats->queued));
538 blkg_stat_add(&stats->avg_queue_size_samples, 1);
539 cfqg_stats_update_group_wait_time(stats);
542 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
544 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
545 struct cfq_group *curr_cfqg) { }
546 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
547 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
548 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
549 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
550 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
551 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
553 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
555 #ifdef CONFIG_CFQ_GROUP_IOSCHED
557 static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg)
559 return blkg_to_pdata(blkg, &blkio_policy_cfq);
562 static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg)
564 return pdata_to_blkg(cfqg);
567 static inline void cfqg_get(struct cfq_group *cfqg)
569 return blkg_get(cfqg_to_blkg(cfqg));
572 static inline void cfqg_put(struct cfq_group *cfqg)
574 return blkg_put(cfqg_to_blkg(cfqg));
577 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
578 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
579 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
580 blkg_path(cfqg_to_blkg((cfqq)->cfqg)), ##args)
582 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
583 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
584 blkg_path(cfqg_to_blkg((cfqg))), ##args) \
586 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
587 struct cfq_group *curr_cfqg, int rw)
589 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
590 cfqg_stats_end_empty_time(&cfqg->stats);
591 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
594 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
595 unsigned long time, unsigned long unaccounted_time)
597 blkg_stat_add(&cfqg->stats.time, time);
598 #ifdef CONFIG_DEBUG_BLK_CGROUP
599 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
603 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
605 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
608 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
610 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
613 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
614 uint64_t bytes, int rw)
616 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
617 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
618 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
621 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
622 uint64_t start_time, uint64_t io_start_time, int rw)
624 struct cfqg_stats *stats = &cfqg->stats;
625 unsigned long long now = sched_clock();
627 if (time_after64(now, io_start_time))
628 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
629 if (time_after64(io_start_time, start_time))
630 blkg_rwstat_add(&stats->wait_time, rw,
631 io_start_time - start_time);
634 static void cfqg_stats_reset(struct blkio_group *blkg)
636 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
637 struct cfqg_stats *stats = &cfqg->stats;
639 /* queued stats shouldn't be cleared */
640 blkg_rwstat_reset(&stats->service_bytes);
641 blkg_rwstat_reset(&stats->serviced);
642 blkg_rwstat_reset(&stats->merged);
643 blkg_rwstat_reset(&stats->service_time);
644 blkg_rwstat_reset(&stats->wait_time);
645 blkg_stat_reset(&stats->time);
646 #ifdef CONFIG_DEBUG_BLK_CGROUP
647 blkg_stat_reset(&stats->unaccounted_time);
648 blkg_stat_reset(&stats->avg_queue_size_sum);
649 blkg_stat_reset(&stats->avg_queue_size_samples);
650 blkg_stat_reset(&stats->dequeue);
651 blkg_stat_reset(&stats->group_wait_time);
652 blkg_stat_reset(&stats->idle_time);
653 blkg_stat_reset(&stats->empty_time);
657 #else /* CONFIG_CFQ_GROUP_IOSCHED */
659 static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg) { return NULL; }
660 static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg) { return NULL; }
661 static inline void cfqg_get(struct cfq_group *cfqg) { }
662 static inline void cfqg_put(struct cfq_group *cfqg) { }
664 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
665 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
666 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
668 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
669 struct cfq_group *curr_cfqg, int rw) { }
670 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
671 unsigned long time, unsigned long unaccounted_time) { }
672 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
673 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
674 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
675 uint64_t bytes, int rw) { }
676 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
677 uint64_t start_time, uint64_t io_start_time, int rw) { }
679 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
681 #define cfq_log(cfqd, fmt, args...) \
682 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
684 /* Traverses through cfq group service trees */
685 #define for_each_cfqg_st(cfqg, i, j, st) \
686 for (i = 0; i <= IDLE_WORKLOAD; i++) \
687 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
688 : &cfqg->service_tree_idle; \
689 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
690 (i == IDLE_WORKLOAD && j == 0); \
691 j++, st = i < IDLE_WORKLOAD ? \
692 &cfqg->service_trees[i][j]: NULL) \
694 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
695 struct cfq_ttime *ttime, bool group_idle)
698 if (!sample_valid(ttime->ttime_samples))
701 slice = cfqd->cfq_group_idle;
703 slice = cfqd->cfq_slice_idle;
704 return ttime->ttime_mean > slice;
707 static inline bool iops_mode(struct cfq_data *cfqd)
710 * If we are not idling on queues and it is a NCQ drive, parallel
711 * execution of requests is on and measuring time is not possible
712 * in most of the cases until and unless we drive shallower queue
713 * depths and that becomes a performance bottleneck. In such cases
714 * switch to start providing fairness in terms of number of IOs.
716 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
722 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
724 if (cfq_class_idle(cfqq))
725 return IDLE_WORKLOAD;
726 if (cfq_class_rt(cfqq))
732 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
734 if (!cfq_cfqq_sync(cfqq))
735 return ASYNC_WORKLOAD;
736 if (!cfq_cfqq_idle_window(cfqq))
737 return SYNC_NOIDLE_WORKLOAD;
738 return SYNC_WORKLOAD;
741 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
742 struct cfq_data *cfqd,
743 struct cfq_group *cfqg)
745 if (wl == IDLE_WORKLOAD)
746 return cfqg->service_tree_idle.count;
748 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
749 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
750 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
753 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
754 struct cfq_group *cfqg)
756 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
757 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
760 static void cfq_dispatch_insert(struct request_queue *, struct request *);
761 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
762 struct cfq_io_cq *cic, struct bio *bio,
765 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
767 /* cic->icq is the first member, %NULL will convert to %NULL */
768 return container_of(icq, struct cfq_io_cq, icq);
771 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
772 struct io_context *ioc)
775 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
779 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
781 return cic->cfqq[is_sync];
784 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
787 cic->cfqq[is_sync] = cfqq;
790 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
792 return cic->icq.q->elevator->elevator_data;
796 * We regard a request as SYNC, if it's either a read or has the SYNC bit
797 * set (in which case it could also be direct WRITE).
799 static inline bool cfq_bio_sync(struct bio *bio)
801 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
805 * scheduler run of queue, if there are requests pending and no one in the
806 * driver that will restart queueing
808 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
810 if (cfqd->busy_queues) {
811 cfq_log(cfqd, "schedule dispatch");
812 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
817 * Scale schedule slice based on io priority. Use the sync time slice only
818 * if a queue is marked sync and has sync io queued. A sync queue with async
819 * io only, should not get full sync slice length.
821 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
824 const int base_slice = cfqd->cfq_slice[sync];
826 WARN_ON(prio >= IOPRIO_BE_NR);
828 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
832 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
834 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
837 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
839 u64 d = delta << CFQ_SERVICE_SHIFT;
841 d = d * CFQ_WEIGHT_DEFAULT;
842 do_div(d, cfqg->weight);
846 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
848 s64 delta = (s64)(vdisktime - min_vdisktime);
850 min_vdisktime = vdisktime;
852 return min_vdisktime;
855 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
857 s64 delta = (s64)(vdisktime - min_vdisktime);
859 min_vdisktime = vdisktime;
861 return min_vdisktime;
864 static void update_min_vdisktime(struct cfq_rb_root *st)
866 struct cfq_group *cfqg;
869 cfqg = rb_entry_cfqg(st->left);
870 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
876 * get averaged number of queues of RT/BE priority.
877 * average is updated, with a formula that gives more weight to higher numbers,
878 * to quickly follows sudden increases and decrease slowly
881 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
882 struct cfq_group *cfqg, bool rt)
884 unsigned min_q, max_q;
885 unsigned mult = cfq_hist_divisor - 1;
886 unsigned round = cfq_hist_divisor / 2;
887 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
889 min_q = min(cfqg->busy_queues_avg[rt], busy);
890 max_q = max(cfqg->busy_queues_avg[rt], busy);
891 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
893 return cfqg->busy_queues_avg[rt];
896 static inline unsigned
897 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
899 struct cfq_rb_root *st = &cfqd->grp_service_tree;
901 return cfq_target_latency * cfqg->weight / st->total_weight;
904 static inline unsigned
905 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
907 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
908 if (cfqd->cfq_latency) {
910 * interested queues (we consider only the ones with the same
911 * priority class in the cfq group)
913 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
915 unsigned sync_slice = cfqd->cfq_slice[1];
916 unsigned expect_latency = sync_slice * iq;
917 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
919 if (expect_latency > group_slice) {
920 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
921 /* scale low_slice according to IO priority
922 * and sync vs async */
924 min(slice, base_low_slice * slice / sync_slice);
925 /* the adapted slice value is scaled to fit all iqs
926 * into the target latency */
927 slice = max(slice * group_slice / expect_latency,
935 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
937 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
939 cfqq->slice_start = jiffies;
940 cfqq->slice_end = jiffies + slice;
941 cfqq->allocated_slice = slice;
942 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
946 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
947 * isn't valid until the first request from the dispatch is activated
948 * and the slice time set.
950 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
952 if (cfq_cfqq_slice_new(cfqq))
954 if (time_before(jiffies, cfqq->slice_end))
961 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
962 * We choose the request that is closest to the head right now. Distance
963 * behind the head is penalized and only allowed to a certain extent.
965 static struct request *
966 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
968 sector_t s1, s2, d1 = 0, d2 = 0;
969 unsigned long back_max;
970 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
971 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
972 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
974 if (rq1 == NULL || rq1 == rq2)
979 if (rq_is_sync(rq1) != rq_is_sync(rq2))
980 return rq_is_sync(rq1) ? rq1 : rq2;
982 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
983 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
985 s1 = blk_rq_pos(rq1);
986 s2 = blk_rq_pos(rq2);
989 * by definition, 1KiB is 2 sectors
991 back_max = cfqd->cfq_back_max * 2;
994 * Strict one way elevator _except_ in the case where we allow
995 * short backward seeks which are biased as twice the cost of a
996 * similar forward seek.
1000 else if (s1 + back_max >= last)
1001 d1 = (last - s1) * cfqd->cfq_back_penalty;
1003 wrap |= CFQ_RQ1_WRAP;
1007 else if (s2 + back_max >= last)
1008 d2 = (last - s2) * cfqd->cfq_back_penalty;
1010 wrap |= CFQ_RQ2_WRAP;
1012 /* Found required data */
1015 * By doing switch() on the bit mask "wrap" we avoid having to
1016 * check two variables for all permutations: --> faster!
1019 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1035 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1038 * Since both rqs are wrapped,
1039 * start with the one that's further behind head
1040 * (--> only *one* back seek required),
1041 * since back seek takes more time than forward.
1051 * The below is leftmost cache rbtree addon
1053 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1055 /* Service tree is empty */
1060 root->left = rb_first(&root->rb);
1063 return rb_entry(root->left, struct cfq_queue, rb_node);
1068 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1071 root->left = rb_first(&root->rb);
1074 return rb_entry_cfqg(root->left);
1079 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1085 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1087 if (root->left == n)
1089 rb_erase_init(n, &root->rb);
1094 * would be nice to take fifo expire time into account as well
1096 static struct request *
1097 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1098 struct request *last)
1100 struct rb_node *rbnext = rb_next(&last->rb_node);
1101 struct rb_node *rbprev = rb_prev(&last->rb_node);
1102 struct request *next = NULL, *prev = NULL;
1104 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1107 prev = rb_entry_rq(rbprev);
1110 next = rb_entry_rq(rbnext);
1112 rbnext = rb_first(&cfqq->sort_list);
1113 if (rbnext && rbnext != &last->rb_node)
1114 next = rb_entry_rq(rbnext);
1117 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1120 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1121 struct cfq_queue *cfqq)
1124 * just an approximation, should be ok.
1126 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1127 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1131 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1133 return cfqg->vdisktime - st->min_vdisktime;
1137 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1139 struct rb_node **node = &st->rb.rb_node;
1140 struct rb_node *parent = NULL;
1141 struct cfq_group *__cfqg;
1142 s64 key = cfqg_key(st, cfqg);
1145 while (*node != NULL) {
1147 __cfqg = rb_entry_cfqg(parent);
1149 if (key < cfqg_key(st, __cfqg))
1150 node = &parent->rb_left;
1152 node = &parent->rb_right;
1158 st->left = &cfqg->rb_node;
1160 rb_link_node(&cfqg->rb_node, parent, node);
1161 rb_insert_color(&cfqg->rb_node, &st->rb);
1165 cfq_update_group_weight(struct cfq_group *cfqg)
1167 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1168 if (cfqg->new_weight) {
1169 cfqg->weight = cfqg->new_weight;
1170 cfqg->new_weight = 0;
1175 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1177 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1179 cfq_update_group_weight(cfqg);
1180 __cfq_group_service_tree_add(st, cfqg);
1181 st->total_weight += cfqg->weight;
1185 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1187 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1188 struct cfq_group *__cfqg;
1192 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1196 * Currently put the group at the end. Later implement something
1197 * so that groups get lesser vtime based on their weights, so that
1198 * if group does not loose all if it was not continuously backlogged.
1200 n = rb_last(&st->rb);
1202 __cfqg = rb_entry_cfqg(n);
1203 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1205 cfqg->vdisktime = st->min_vdisktime;
1206 cfq_group_service_tree_add(st, cfqg);
1210 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1212 st->total_weight -= cfqg->weight;
1213 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1214 cfq_rb_erase(&cfqg->rb_node, st);
1218 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1220 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1222 BUG_ON(cfqg->nr_cfqq < 1);
1225 /* If there are other cfq queues under this group, don't delete it */
1229 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1230 cfq_group_service_tree_del(st, cfqg);
1231 cfqg->saved_workload_slice = 0;
1232 cfqg_stats_update_dequeue(cfqg);
1235 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1236 unsigned int *unaccounted_time)
1238 unsigned int slice_used;
1241 * Queue got expired before even a single request completed or
1242 * got expired immediately after first request completion.
1244 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1246 * Also charge the seek time incurred to the group, otherwise
1247 * if there are mutiple queues in the group, each can dispatch
1248 * a single request on seeky media and cause lots of seek time
1249 * and group will never know it.
1251 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1254 slice_used = jiffies - cfqq->slice_start;
1255 if (slice_used > cfqq->allocated_slice) {
1256 *unaccounted_time = slice_used - cfqq->allocated_slice;
1257 slice_used = cfqq->allocated_slice;
1259 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1260 *unaccounted_time += cfqq->slice_start -
1261 cfqq->dispatch_start;
1267 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1268 struct cfq_queue *cfqq)
1270 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1271 unsigned int used_sl, charge, unaccounted_sl = 0;
1272 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1273 - cfqg->service_tree_idle.count;
1275 BUG_ON(nr_sync < 0);
1276 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1278 if (iops_mode(cfqd))
1279 charge = cfqq->slice_dispatch;
1280 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1281 charge = cfqq->allocated_slice;
1283 /* Can't update vdisktime while group is on service tree */
1284 cfq_group_service_tree_del(st, cfqg);
1285 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1286 /* If a new weight was requested, update now, off tree */
1287 cfq_group_service_tree_add(st, cfqg);
1289 /* This group is being expired. Save the context */
1290 if (time_after(cfqd->workload_expires, jiffies)) {
1291 cfqg->saved_workload_slice = cfqd->workload_expires
1293 cfqg->saved_workload = cfqd->serving_type;
1294 cfqg->saved_serving_prio = cfqd->serving_prio;
1296 cfqg->saved_workload_slice = 0;
1298 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1300 cfq_log_cfqq(cfqq->cfqd, cfqq,
1301 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1302 used_sl, cfqq->slice_dispatch, charge,
1303 iops_mode(cfqd), cfqq->nr_sectors);
1304 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1305 cfqg_stats_set_start_empty_time(cfqg);
1309 * cfq_init_cfqg_base - initialize base part of a cfq_group
1310 * @cfqg: cfq_group to initialize
1312 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1313 * is enabled or not.
1315 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1317 struct cfq_rb_root *st;
1320 for_each_cfqg_st(cfqg, i, j, st)
1322 RB_CLEAR_NODE(&cfqg->rb_node);
1324 cfqg->ttime.last_end_request = jiffies;
1327 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1328 static void cfq_init_blkio_group(struct blkio_group *blkg)
1330 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1332 cfq_init_cfqg_base(cfqg);
1333 cfqg->weight = blkg->blkcg->cfq_weight;
1337 * Search for the cfq group current task belongs to. request_queue lock must
1340 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1341 struct blkio_cgroup *blkcg)
1343 struct request_queue *q = cfqd->queue;
1344 struct cfq_group *cfqg = NULL;
1346 /* avoid lookup for the common case where there's no blkio cgroup */
1347 if (blkcg == &blkio_root_cgroup) {
1348 cfqg = cfqd->root_group;
1350 struct blkio_group *blkg;
1352 blkg = blkg_lookup_create(blkcg, q, false);
1354 cfqg = blkg_to_cfqg(blkg);
1360 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1362 /* Currently, all async queues are mapped to root group */
1363 if (!cfq_cfqq_sync(cfqq))
1364 cfqg = cfqq->cfqd->root_group;
1367 /* cfqq reference on cfqg */
1371 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1372 struct blkg_policy_data *pd, int off)
1374 struct cfq_group *cfqg = (void *)pd->pdata;
1376 if (!cfqg->dev_weight)
1378 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1381 static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1382 struct seq_file *sf)
1384 blkcg_print_blkgs(sf, cgroup_to_blkio_cgroup(cgrp),
1385 cfqg_prfill_weight_device, BLKIO_POLICY_PROP, 0,
1390 static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1391 struct seq_file *sf)
1393 seq_printf(sf, "%u\n", cgroup_to_blkio_cgroup(cgrp)->cfq_weight);
1397 static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1400 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1401 struct blkg_conf_ctx ctx;
1402 struct cfq_group *cfqg;
1405 ret = blkg_conf_prep(blkcg, buf, &ctx);
1410 cfqg = blkg_to_cfqg(ctx.blkg);
1411 if (cfqg && (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN &&
1412 ctx.v <= CFQ_WEIGHT_MAX))) {
1413 cfqg->dev_weight = ctx.v;
1414 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1418 blkg_conf_finish(&ctx);
1422 static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1424 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1425 struct blkio_group *blkg;
1426 struct hlist_node *n;
1428 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1431 spin_lock_irq(&blkcg->lock);
1432 blkcg->cfq_weight = (unsigned int)val;
1434 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1435 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1437 if (cfqg && !cfqg->dev_weight)
1438 cfqg->new_weight = blkcg->cfq_weight;
1441 spin_unlock_irq(&blkcg->lock);
1445 #ifdef CONFIG_DEBUG_BLK_CGROUP
1446 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1447 struct blkg_policy_data *pd, int off)
1449 struct cfq_group *cfqg = (void *)pd->pdata;
1450 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1454 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1457 __blkg_prfill_u64(sf, pd, v);
1461 /* print avg_queue_size */
1462 static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1463 struct seq_file *sf)
1465 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1467 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1468 BLKIO_POLICY_PROP, 0, false);
1471 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1473 static struct cftype cfq_blkcg_files[] = {
1475 .name = "weight_device",
1476 .read_seq_string = cfqg_print_weight_device,
1477 .write_string = cfqg_set_weight_device,
1478 .max_write_len = 256,
1482 .read_seq_string = cfq_print_weight,
1483 .write_u64 = cfq_set_weight,
1487 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1488 offsetof(struct cfq_group, stats.time)),
1489 .read_seq_string = blkcg_print_stat,
1493 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1494 offsetof(struct cfq_group, stats.sectors)),
1495 .read_seq_string = blkcg_print_stat,
1498 .name = "io_service_bytes",
1499 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1500 offsetof(struct cfq_group, stats.service_bytes)),
1501 .read_seq_string = blkcg_print_rwstat,
1504 .name = "io_serviced",
1505 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1506 offsetof(struct cfq_group, stats.serviced)),
1507 .read_seq_string = blkcg_print_rwstat,
1510 .name = "io_service_time",
1511 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1512 offsetof(struct cfq_group, stats.service_time)),
1513 .read_seq_string = blkcg_print_rwstat,
1516 .name = "io_wait_time",
1517 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1518 offsetof(struct cfq_group, stats.wait_time)),
1519 .read_seq_string = blkcg_print_rwstat,
1522 .name = "io_merged",
1523 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1524 offsetof(struct cfq_group, stats.merged)),
1525 .read_seq_string = blkcg_print_rwstat,
1528 .name = "io_queued",
1529 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1530 offsetof(struct cfq_group, stats.queued)),
1531 .read_seq_string = blkcg_print_rwstat,
1533 #ifdef CONFIG_DEBUG_BLK_CGROUP
1535 .name = "avg_queue_size",
1536 .read_seq_string = cfqg_print_avg_queue_size,
1539 .name = "group_wait_time",
1540 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1541 offsetof(struct cfq_group, stats.group_wait_time)),
1542 .read_seq_string = blkcg_print_stat,
1545 .name = "idle_time",
1546 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1547 offsetof(struct cfq_group, stats.idle_time)),
1548 .read_seq_string = blkcg_print_stat,
1551 .name = "empty_time",
1552 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1553 offsetof(struct cfq_group, stats.empty_time)),
1554 .read_seq_string = blkcg_print_stat,
1558 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1559 offsetof(struct cfq_group, stats.dequeue)),
1560 .read_seq_string = blkcg_print_stat,
1563 .name = "unaccounted_time",
1564 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
1565 offsetof(struct cfq_group, stats.unaccounted_time)),
1566 .read_seq_string = blkcg_print_stat,
1568 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1571 #else /* GROUP_IOSCHED */
1572 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1573 struct blkio_cgroup *blkcg)
1575 return cfqd->root_group;
1579 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1583 #endif /* GROUP_IOSCHED */
1586 * The cfqd->service_trees holds all pending cfq_queue's that have
1587 * requests waiting to be processed. It is sorted in the order that
1588 * we will service the queues.
1590 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1593 struct rb_node **p, *parent;
1594 struct cfq_queue *__cfqq;
1595 unsigned long rb_key;
1596 struct cfq_rb_root *service_tree;
1600 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1602 if (cfq_class_idle(cfqq)) {
1603 rb_key = CFQ_IDLE_DELAY;
1604 parent = rb_last(&service_tree->rb);
1605 if (parent && parent != &cfqq->rb_node) {
1606 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1607 rb_key += __cfqq->rb_key;
1610 } else if (!add_front) {
1612 * Get our rb key offset. Subtract any residual slice
1613 * value carried from last service. A negative resid
1614 * count indicates slice overrun, and this should position
1615 * the next service time further away in the tree.
1617 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1618 rb_key -= cfqq->slice_resid;
1619 cfqq->slice_resid = 0;
1622 __cfqq = cfq_rb_first(service_tree);
1623 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1626 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1629 * same position, nothing more to do
1631 if (rb_key == cfqq->rb_key &&
1632 cfqq->service_tree == service_tree)
1635 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1636 cfqq->service_tree = NULL;
1641 cfqq->service_tree = service_tree;
1642 p = &service_tree->rb.rb_node;
1647 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1650 * sort by key, that represents service time.
1652 if (time_before(rb_key, __cfqq->rb_key))
1655 n = &(*p)->rb_right;
1663 service_tree->left = &cfqq->rb_node;
1665 cfqq->rb_key = rb_key;
1666 rb_link_node(&cfqq->rb_node, parent, p);
1667 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1668 service_tree->count++;
1669 if (add_front || !new_cfqq)
1671 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1674 static struct cfq_queue *
1675 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1676 sector_t sector, struct rb_node **ret_parent,
1677 struct rb_node ***rb_link)
1679 struct rb_node **p, *parent;
1680 struct cfq_queue *cfqq = NULL;
1688 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1691 * Sort strictly based on sector. Smallest to the left,
1692 * largest to the right.
1694 if (sector > blk_rq_pos(cfqq->next_rq))
1695 n = &(*p)->rb_right;
1696 else if (sector < blk_rq_pos(cfqq->next_rq))
1704 *ret_parent = parent;
1710 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1712 struct rb_node **p, *parent;
1713 struct cfq_queue *__cfqq;
1716 rb_erase(&cfqq->p_node, cfqq->p_root);
1717 cfqq->p_root = NULL;
1720 if (cfq_class_idle(cfqq))
1725 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1726 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1727 blk_rq_pos(cfqq->next_rq), &parent, &p);
1729 rb_link_node(&cfqq->p_node, parent, p);
1730 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1732 cfqq->p_root = NULL;
1736 * Update cfqq's position in the service tree.
1738 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1741 * Resorting requires the cfqq to be on the RR list already.
1743 if (cfq_cfqq_on_rr(cfqq)) {
1744 cfq_service_tree_add(cfqd, cfqq, 0);
1745 cfq_prio_tree_add(cfqd, cfqq);
1750 * add to busy list of queues for service, trying to be fair in ordering
1751 * the pending list according to last request service
1753 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1755 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1756 BUG_ON(cfq_cfqq_on_rr(cfqq));
1757 cfq_mark_cfqq_on_rr(cfqq);
1758 cfqd->busy_queues++;
1759 if (cfq_cfqq_sync(cfqq))
1760 cfqd->busy_sync_queues++;
1762 cfq_resort_rr_list(cfqd, cfqq);
1766 * Called when the cfqq no longer has requests pending, remove it from
1769 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1771 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1772 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1773 cfq_clear_cfqq_on_rr(cfqq);
1775 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1776 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1777 cfqq->service_tree = NULL;
1780 rb_erase(&cfqq->p_node, cfqq->p_root);
1781 cfqq->p_root = NULL;
1784 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1785 BUG_ON(!cfqd->busy_queues);
1786 cfqd->busy_queues--;
1787 if (cfq_cfqq_sync(cfqq))
1788 cfqd->busy_sync_queues--;
1792 * rb tree support functions
1794 static void cfq_del_rq_rb(struct request *rq)
1796 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1797 const int sync = rq_is_sync(rq);
1799 BUG_ON(!cfqq->queued[sync]);
1800 cfqq->queued[sync]--;
1802 elv_rb_del(&cfqq->sort_list, rq);
1804 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1806 * Queue will be deleted from service tree when we actually
1807 * expire it later. Right now just remove it from prio tree
1811 rb_erase(&cfqq->p_node, cfqq->p_root);
1812 cfqq->p_root = NULL;
1817 static void cfq_add_rq_rb(struct request *rq)
1819 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1820 struct cfq_data *cfqd = cfqq->cfqd;
1821 struct request *prev;
1823 cfqq->queued[rq_is_sync(rq)]++;
1825 elv_rb_add(&cfqq->sort_list, rq);
1827 if (!cfq_cfqq_on_rr(cfqq))
1828 cfq_add_cfqq_rr(cfqd, cfqq);
1831 * check if this request is a better next-serve candidate
1833 prev = cfqq->next_rq;
1834 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1837 * adjust priority tree position, if ->next_rq changes
1839 if (prev != cfqq->next_rq)
1840 cfq_prio_tree_add(cfqd, cfqq);
1842 BUG_ON(!cfqq->next_rq);
1845 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1847 elv_rb_del(&cfqq->sort_list, rq);
1848 cfqq->queued[rq_is_sync(rq)]--;
1849 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1851 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1855 static struct request *
1856 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1858 struct task_struct *tsk = current;
1859 struct cfq_io_cq *cic;
1860 struct cfq_queue *cfqq;
1862 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1866 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1868 sector_t sector = bio->bi_sector + bio_sectors(bio);
1870 return elv_rb_find(&cfqq->sort_list, sector);
1876 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1878 struct cfq_data *cfqd = q->elevator->elevator_data;
1880 cfqd->rq_in_driver++;
1881 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1882 cfqd->rq_in_driver);
1884 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1887 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1889 struct cfq_data *cfqd = q->elevator->elevator_data;
1891 WARN_ON(!cfqd->rq_in_driver);
1892 cfqd->rq_in_driver--;
1893 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1894 cfqd->rq_in_driver);
1897 static void cfq_remove_request(struct request *rq)
1899 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1901 if (cfqq->next_rq == rq)
1902 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1904 list_del_init(&rq->queuelist);
1907 cfqq->cfqd->rq_queued--;
1908 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1909 if (rq->cmd_flags & REQ_PRIO) {
1910 WARN_ON(!cfqq->prio_pending);
1911 cfqq->prio_pending--;
1915 static int cfq_merge(struct request_queue *q, struct request **req,
1918 struct cfq_data *cfqd = q->elevator->elevator_data;
1919 struct request *__rq;
1921 __rq = cfq_find_rq_fmerge(cfqd, bio);
1922 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1924 return ELEVATOR_FRONT_MERGE;
1927 return ELEVATOR_NO_MERGE;
1930 static void cfq_merged_request(struct request_queue *q, struct request *req,
1933 if (type == ELEVATOR_FRONT_MERGE) {
1934 struct cfq_queue *cfqq = RQ_CFQQ(req);
1936 cfq_reposition_rq_rb(cfqq, req);
1940 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1943 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1947 cfq_merged_requests(struct request_queue *q, struct request *rq,
1948 struct request *next)
1950 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1951 struct cfq_data *cfqd = q->elevator->elevator_data;
1954 * reposition in fifo if next is older than rq
1956 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1957 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1958 list_move(&rq->queuelist, &next->queuelist);
1959 rq_set_fifo_time(rq, rq_fifo_time(next));
1962 if (cfqq->next_rq == next)
1964 cfq_remove_request(next);
1965 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1967 cfqq = RQ_CFQQ(next);
1969 * all requests of this queue are merged to other queues, delete it
1970 * from the service tree. If it's the active_queue,
1971 * cfq_dispatch_requests() will choose to expire it or do idle
1973 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1974 cfqq != cfqd->active_queue)
1975 cfq_del_cfqq_rr(cfqd, cfqq);
1978 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1981 struct cfq_data *cfqd = q->elevator->elevator_data;
1982 struct cfq_io_cq *cic;
1983 struct cfq_queue *cfqq;
1986 * Disallow merge of a sync bio into an async request.
1988 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1992 * Lookup the cfqq that this bio will be queued with and allow
1993 * merge only if rq is queued there.
1995 cic = cfq_cic_lookup(cfqd, current->io_context);
1999 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2000 return cfqq == RQ_CFQQ(rq);
2003 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2005 del_timer(&cfqd->idle_slice_timer);
2006 cfqg_stats_update_idle_time(cfqq->cfqg);
2009 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2010 struct cfq_queue *cfqq)
2013 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
2014 cfqd->serving_prio, cfqd->serving_type);
2015 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2016 cfqq->slice_start = 0;
2017 cfqq->dispatch_start = jiffies;
2018 cfqq->allocated_slice = 0;
2019 cfqq->slice_end = 0;
2020 cfqq->slice_dispatch = 0;
2021 cfqq->nr_sectors = 0;
2023 cfq_clear_cfqq_wait_request(cfqq);
2024 cfq_clear_cfqq_must_dispatch(cfqq);
2025 cfq_clear_cfqq_must_alloc_slice(cfqq);
2026 cfq_clear_cfqq_fifo_expire(cfqq);
2027 cfq_mark_cfqq_slice_new(cfqq);
2029 cfq_del_timer(cfqd, cfqq);
2032 cfqd->active_queue = cfqq;
2036 * current cfqq expired its slice (or was too idle), select new one
2039 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2042 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2044 if (cfq_cfqq_wait_request(cfqq))
2045 cfq_del_timer(cfqd, cfqq);
2047 cfq_clear_cfqq_wait_request(cfqq);
2048 cfq_clear_cfqq_wait_busy(cfqq);
2051 * If this cfqq is shared between multiple processes, check to
2052 * make sure that those processes are still issuing I/Os within
2053 * the mean seek distance. If not, it may be time to break the
2054 * queues apart again.
2056 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2057 cfq_mark_cfqq_split_coop(cfqq);
2060 * store what was left of this slice, if the queue idled/timed out
2063 if (cfq_cfqq_slice_new(cfqq))
2064 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2066 cfqq->slice_resid = cfqq->slice_end - jiffies;
2067 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2070 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2072 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2073 cfq_del_cfqq_rr(cfqd, cfqq);
2075 cfq_resort_rr_list(cfqd, cfqq);
2077 if (cfqq == cfqd->active_queue)
2078 cfqd->active_queue = NULL;
2080 if (cfqd->active_cic) {
2081 put_io_context(cfqd->active_cic->icq.ioc);
2082 cfqd->active_cic = NULL;
2086 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2088 struct cfq_queue *cfqq = cfqd->active_queue;
2091 __cfq_slice_expired(cfqd, cfqq, timed_out);
2095 * Get next queue for service. Unless we have a queue preemption,
2096 * we'll simply select the first cfqq in the service tree.
2098 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2100 struct cfq_rb_root *service_tree =
2101 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
2102 cfqd->serving_type);
2104 if (!cfqd->rq_queued)
2107 /* There is nothing to dispatch */
2110 if (RB_EMPTY_ROOT(&service_tree->rb))
2112 return cfq_rb_first(service_tree);
2115 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2117 struct cfq_group *cfqg;
2118 struct cfq_queue *cfqq;
2120 struct cfq_rb_root *st;
2122 if (!cfqd->rq_queued)
2125 cfqg = cfq_get_next_cfqg(cfqd);
2129 for_each_cfqg_st(cfqg, i, j, st)
2130 if ((cfqq = cfq_rb_first(st)) != NULL)
2136 * Get and set a new active queue for service.
2138 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2139 struct cfq_queue *cfqq)
2142 cfqq = cfq_get_next_queue(cfqd);
2144 __cfq_set_active_queue(cfqd, cfqq);
2148 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2151 if (blk_rq_pos(rq) >= cfqd->last_position)
2152 return blk_rq_pos(rq) - cfqd->last_position;
2154 return cfqd->last_position - blk_rq_pos(rq);
2157 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2160 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2163 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2164 struct cfq_queue *cur_cfqq)
2166 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2167 struct rb_node *parent, *node;
2168 struct cfq_queue *__cfqq;
2169 sector_t sector = cfqd->last_position;
2171 if (RB_EMPTY_ROOT(root))
2175 * First, if we find a request starting at the end of the last
2176 * request, choose it.
2178 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2183 * If the exact sector wasn't found, the parent of the NULL leaf
2184 * will contain the closest sector.
2186 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2187 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2190 if (blk_rq_pos(__cfqq->next_rq) < sector)
2191 node = rb_next(&__cfqq->p_node);
2193 node = rb_prev(&__cfqq->p_node);
2197 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2198 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2206 * cur_cfqq - passed in so that we don't decide that the current queue is
2207 * closely cooperating with itself.
2209 * So, basically we're assuming that that cur_cfqq has dispatched at least
2210 * one request, and that cfqd->last_position reflects a position on the disk
2211 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2214 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2215 struct cfq_queue *cur_cfqq)
2217 struct cfq_queue *cfqq;
2219 if (cfq_class_idle(cur_cfqq))
2221 if (!cfq_cfqq_sync(cur_cfqq))
2223 if (CFQQ_SEEKY(cur_cfqq))
2227 * Don't search priority tree if it's the only queue in the group.
2229 if (cur_cfqq->cfqg->nr_cfqq == 1)
2233 * We should notice if some of the queues are cooperating, eg
2234 * working closely on the same area of the disk. In that case,
2235 * we can group them together and don't waste time idling.
2237 cfqq = cfqq_close(cfqd, cur_cfqq);
2241 /* If new queue belongs to different cfq_group, don't choose it */
2242 if (cur_cfqq->cfqg != cfqq->cfqg)
2246 * It only makes sense to merge sync queues.
2248 if (!cfq_cfqq_sync(cfqq))
2250 if (CFQQ_SEEKY(cfqq))
2254 * Do not merge queues of different priority classes
2256 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2263 * Determine whether we should enforce idle window for this queue.
2266 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2268 enum wl_prio_t prio = cfqq_prio(cfqq);
2269 struct cfq_rb_root *service_tree = cfqq->service_tree;
2271 BUG_ON(!service_tree);
2272 BUG_ON(!service_tree->count);
2274 if (!cfqd->cfq_slice_idle)
2277 /* We never do for idle class queues. */
2278 if (prio == IDLE_WORKLOAD)
2281 /* We do for queues that were marked with idle window flag. */
2282 if (cfq_cfqq_idle_window(cfqq) &&
2283 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2287 * Otherwise, we do only if they are the last ones
2288 * in their service tree.
2290 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2291 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
2293 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2294 service_tree->count);
2298 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2300 struct cfq_queue *cfqq = cfqd->active_queue;
2301 struct cfq_io_cq *cic;
2302 unsigned long sl, group_idle = 0;
2305 * SSD device without seek penalty, disable idling. But only do so
2306 * for devices that support queuing, otherwise we still have a problem
2307 * with sync vs async workloads.
2309 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2312 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2313 WARN_ON(cfq_cfqq_slice_new(cfqq));
2316 * idle is disabled, either manually or by past process history
2318 if (!cfq_should_idle(cfqd, cfqq)) {
2319 /* no queue idling. Check for group idling */
2320 if (cfqd->cfq_group_idle)
2321 group_idle = cfqd->cfq_group_idle;
2327 * still active requests from this queue, don't idle
2329 if (cfqq->dispatched)
2333 * task has exited, don't wait
2335 cic = cfqd->active_cic;
2336 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2340 * If our average think time is larger than the remaining time
2341 * slice, then don't idle. This avoids overrunning the allotted
2344 if (sample_valid(cic->ttime.ttime_samples) &&
2345 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2346 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2347 cic->ttime.ttime_mean);
2351 /* There are other queues in the group, don't do group idle */
2352 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2355 cfq_mark_cfqq_wait_request(cfqq);
2358 sl = cfqd->cfq_group_idle;
2360 sl = cfqd->cfq_slice_idle;
2362 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2363 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2364 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2365 group_idle ? 1 : 0);
2369 * Move request from internal lists to the request queue dispatch list.
2371 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2373 struct cfq_data *cfqd = q->elevator->elevator_data;
2374 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2376 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2378 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2379 cfq_remove_request(rq);
2381 (RQ_CFQG(rq))->dispatched++;
2382 elv_dispatch_sort(q, rq);
2384 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2385 cfqq->nr_sectors += blk_rq_sectors(rq);
2386 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2390 * return expired entry, or NULL to just start from scratch in rbtree
2392 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2394 struct request *rq = NULL;
2396 if (cfq_cfqq_fifo_expire(cfqq))
2399 cfq_mark_cfqq_fifo_expire(cfqq);
2401 if (list_empty(&cfqq->fifo))
2404 rq = rq_entry_fifo(cfqq->fifo.next);
2405 if (time_before(jiffies, rq_fifo_time(rq)))
2408 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2413 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2415 const int base_rq = cfqd->cfq_slice_async_rq;
2417 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2419 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2423 * Must be called with the queue_lock held.
2425 static int cfqq_process_refs(struct cfq_queue *cfqq)
2427 int process_refs, io_refs;
2429 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2430 process_refs = cfqq->ref - io_refs;
2431 BUG_ON(process_refs < 0);
2432 return process_refs;
2435 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2437 int process_refs, new_process_refs;
2438 struct cfq_queue *__cfqq;
2441 * If there are no process references on the new_cfqq, then it is
2442 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2443 * chain may have dropped their last reference (not just their
2444 * last process reference).
2446 if (!cfqq_process_refs(new_cfqq))
2449 /* Avoid a circular list and skip interim queue merges */
2450 while ((__cfqq = new_cfqq->new_cfqq)) {
2456 process_refs = cfqq_process_refs(cfqq);
2457 new_process_refs = cfqq_process_refs(new_cfqq);
2459 * If the process for the cfqq has gone away, there is no
2460 * sense in merging the queues.
2462 if (process_refs == 0 || new_process_refs == 0)
2466 * Merge in the direction of the lesser amount of work.
2468 if (new_process_refs >= process_refs) {
2469 cfqq->new_cfqq = new_cfqq;
2470 new_cfqq->ref += process_refs;
2472 new_cfqq->new_cfqq = cfqq;
2473 cfqq->ref += new_process_refs;
2477 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2478 struct cfq_group *cfqg, enum wl_prio_t prio)
2480 struct cfq_queue *queue;
2482 bool key_valid = false;
2483 unsigned long lowest_key = 0;
2484 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2486 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2487 /* select the one with lowest rb_key */
2488 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2490 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2491 lowest_key = queue->rb_key;
2500 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2504 struct cfq_rb_root *st;
2505 unsigned group_slice;
2506 enum wl_prio_t original_prio = cfqd->serving_prio;
2508 /* Choose next priority. RT > BE > IDLE */
2509 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2510 cfqd->serving_prio = RT_WORKLOAD;
2511 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2512 cfqd->serving_prio = BE_WORKLOAD;
2514 cfqd->serving_prio = IDLE_WORKLOAD;
2515 cfqd->workload_expires = jiffies + 1;
2519 if (original_prio != cfqd->serving_prio)
2523 * For RT and BE, we have to choose also the type
2524 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2527 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2531 * check workload expiration, and that we still have other queues ready
2533 if (count && !time_after(jiffies, cfqd->workload_expires))
2537 /* otherwise select new workload type */
2538 cfqd->serving_type =
2539 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2540 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2544 * the workload slice is computed as a fraction of target latency
2545 * proportional to the number of queues in that workload, over
2546 * all the queues in the same priority class
2548 group_slice = cfq_group_slice(cfqd, cfqg);
2550 slice = group_slice * count /
2551 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2552 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2554 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2558 * Async queues are currently system wide. Just taking
2559 * proportion of queues with-in same group will lead to higher
2560 * async ratio system wide as generally root group is going
2561 * to have higher weight. A more accurate thing would be to
2562 * calculate system wide asnc/sync ratio.
2564 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2565 tmp = tmp/cfqd->busy_queues;
2566 slice = min_t(unsigned, slice, tmp);
2568 /* async workload slice is scaled down according to
2569 * the sync/async slice ratio. */
2570 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2572 /* sync workload slice is at least 2 * cfq_slice_idle */
2573 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2575 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2576 cfq_log(cfqd, "workload slice:%d", slice);
2577 cfqd->workload_expires = jiffies + slice;
2580 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2582 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2583 struct cfq_group *cfqg;
2585 if (RB_EMPTY_ROOT(&st->rb))
2587 cfqg = cfq_rb_first_group(st);
2588 update_min_vdisktime(st);
2592 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2594 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2596 cfqd->serving_group = cfqg;
2598 /* Restore the workload type data */
2599 if (cfqg->saved_workload_slice) {
2600 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2601 cfqd->serving_type = cfqg->saved_workload;
2602 cfqd->serving_prio = cfqg->saved_serving_prio;
2604 cfqd->workload_expires = jiffies - 1;
2606 choose_service_tree(cfqd, cfqg);
2610 * Select a queue for service. If we have a current active queue,
2611 * check whether to continue servicing it, or retrieve and set a new one.
2613 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2615 struct cfq_queue *cfqq, *new_cfqq = NULL;
2617 cfqq = cfqd->active_queue;
2621 if (!cfqd->rq_queued)
2625 * We were waiting for group to get backlogged. Expire the queue
2627 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2631 * The active queue has run out of time, expire it and select new.
2633 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2635 * If slice had not expired at the completion of last request
2636 * we might not have turned on wait_busy flag. Don't expire
2637 * the queue yet. Allow the group to get backlogged.
2639 * The very fact that we have used the slice, that means we
2640 * have been idling all along on this queue and it should be
2641 * ok to wait for this request to complete.
2643 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2644 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2648 goto check_group_idle;
2652 * The active queue has requests and isn't expired, allow it to
2655 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2659 * If another queue has a request waiting within our mean seek
2660 * distance, let it run. The expire code will check for close
2661 * cooperators and put the close queue at the front of the service
2662 * tree. If possible, merge the expiring queue with the new cfqq.
2664 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2666 if (!cfqq->new_cfqq)
2667 cfq_setup_merge(cfqq, new_cfqq);
2672 * No requests pending. If the active queue still has requests in
2673 * flight or is idling for a new request, allow either of these
2674 * conditions to happen (or time out) before selecting a new queue.
2676 if (timer_pending(&cfqd->idle_slice_timer)) {
2682 * This is a deep seek queue, but the device is much faster than
2683 * the queue can deliver, don't idle
2685 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2686 (cfq_cfqq_slice_new(cfqq) ||
2687 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2688 cfq_clear_cfqq_deep(cfqq);
2689 cfq_clear_cfqq_idle_window(cfqq);
2692 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2698 * If group idle is enabled and there are requests dispatched from
2699 * this group, wait for requests to complete.
2702 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2703 cfqq->cfqg->dispatched &&
2704 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2710 cfq_slice_expired(cfqd, 0);
2713 * Current queue expired. Check if we have to switch to a new
2717 cfq_choose_cfqg(cfqd);
2719 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2724 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2728 while (cfqq->next_rq) {
2729 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2733 BUG_ON(!list_empty(&cfqq->fifo));
2735 /* By default cfqq is not expired if it is empty. Do it explicitly */
2736 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2741 * Drain our current requests. Used for barriers and when switching
2742 * io schedulers on-the-fly.
2744 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2746 struct cfq_queue *cfqq;
2749 /* Expire the timeslice of the current active queue first */
2750 cfq_slice_expired(cfqd, 0);
2751 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2752 __cfq_set_active_queue(cfqd, cfqq);
2753 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2756 BUG_ON(cfqd->busy_queues);
2758 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2762 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2763 struct cfq_queue *cfqq)
2765 /* the queue hasn't finished any request, can't estimate */
2766 if (cfq_cfqq_slice_new(cfqq))
2768 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2775 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2777 unsigned int max_dispatch;
2780 * Drain async requests before we start sync IO
2782 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2786 * If this is an async queue and we have sync IO in flight, let it wait
2788 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2791 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2792 if (cfq_class_idle(cfqq))
2796 * Does this cfqq already have too much IO in flight?
2798 if (cfqq->dispatched >= max_dispatch) {
2799 bool promote_sync = false;
2801 * idle queue must always only have a single IO in flight
2803 if (cfq_class_idle(cfqq))
2807 * If there is only one sync queue
2808 * we can ignore async queue here and give the sync
2809 * queue no dispatch limit. The reason is a sync queue can
2810 * preempt async queue, limiting the sync queue doesn't make
2811 * sense. This is useful for aiostress test.
2813 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2814 promote_sync = true;
2817 * We have other queues, don't allow more IO from this one
2819 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2824 * Sole queue user, no limit
2826 if (cfqd->busy_queues == 1 || promote_sync)
2830 * Normally we start throttling cfqq when cfq_quantum/2
2831 * requests have been dispatched. But we can drive
2832 * deeper queue depths at the beginning of slice
2833 * subjected to upper limit of cfq_quantum.
2835 max_dispatch = cfqd->cfq_quantum;
2839 * Async queues must wait a bit before being allowed dispatch.
2840 * We also ramp up the dispatch depth gradually for async IO,
2841 * based on the last sync IO we serviced
2843 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2844 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2847 depth = last_sync / cfqd->cfq_slice[1];
2848 if (!depth && !cfqq->dispatched)
2850 if (depth < max_dispatch)
2851 max_dispatch = depth;
2855 * If we're below the current max, allow a dispatch
2857 return cfqq->dispatched < max_dispatch;
2861 * Dispatch a request from cfqq, moving them to the request queue
2864 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2868 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2870 if (!cfq_may_dispatch(cfqd, cfqq))
2874 * follow expired path, else get first next available
2876 rq = cfq_check_fifo(cfqq);
2881 * insert request into driver dispatch list
2883 cfq_dispatch_insert(cfqd->queue, rq);
2885 if (!cfqd->active_cic) {
2886 struct cfq_io_cq *cic = RQ_CIC(rq);
2888 atomic_long_inc(&cic->icq.ioc->refcount);
2889 cfqd->active_cic = cic;
2896 * Find the cfqq that we need to service and move a request from that to the
2899 static int cfq_dispatch_requests(struct request_queue *q, int force)
2901 struct cfq_data *cfqd = q->elevator->elevator_data;
2902 struct cfq_queue *cfqq;
2904 if (!cfqd->busy_queues)
2907 if (unlikely(force))
2908 return cfq_forced_dispatch(cfqd);
2910 cfqq = cfq_select_queue(cfqd);
2915 * Dispatch a request from this cfqq, if it is allowed
2917 if (!cfq_dispatch_request(cfqd, cfqq))
2920 cfqq->slice_dispatch++;
2921 cfq_clear_cfqq_must_dispatch(cfqq);
2924 * expire an async queue immediately if it has used up its slice. idle
2925 * queue always expire after 1 dispatch round.
2927 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2928 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2929 cfq_class_idle(cfqq))) {
2930 cfqq->slice_end = jiffies + 1;
2931 cfq_slice_expired(cfqd, 0);
2934 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2939 * task holds one reference to the queue, dropped when task exits. each rq
2940 * in-flight on this queue also holds a reference, dropped when rq is freed.
2942 * Each cfq queue took a reference on the parent group. Drop it now.
2943 * queue lock must be held here.
2945 static void cfq_put_queue(struct cfq_queue *cfqq)
2947 struct cfq_data *cfqd = cfqq->cfqd;
2948 struct cfq_group *cfqg;
2950 BUG_ON(cfqq->ref <= 0);
2956 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2957 BUG_ON(rb_first(&cfqq->sort_list));
2958 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2961 if (unlikely(cfqd->active_queue == cfqq)) {
2962 __cfq_slice_expired(cfqd, cfqq, 0);
2963 cfq_schedule_dispatch(cfqd);
2966 BUG_ON(cfq_cfqq_on_rr(cfqq));
2967 kmem_cache_free(cfq_pool, cfqq);
2971 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2973 struct cfq_queue *__cfqq, *next;
2976 * If this queue was scheduled to merge with another queue, be
2977 * sure to drop the reference taken on that queue (and others in
2978 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2980 __cfqq = cfqq->new_cfqq;
2982 if (__cfqq == cfqq) {
2983 WARN(1, "cfqq->new_cfqq loop detected\n");
2986 next = __cfqq->new_cfqq;
2987 cfq_put_queue(__cfqq);
2992 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2994 if (unlikely(cfqq == cfqd->active_queue)) {
2995 __cfq_slice_expired(cfqd, cfqq, 0);
2996 cfq_schedule_dispatch(cfqd);
2999 cfq_put_cooperator(cfqq);
3001 cfq_put_queue(cfqq);
3004 static void cfq_init_icq(struct io_cq *icq)
3006 struct cfq_io_cq *cic = icq_to_cic(icq);
3008 cic->ttime.last_end_request = jiffies;
3011 static void cfq_exit_icq(struct io_cq *icq)
3013 struct cfq_io_cq *cic = icq_to_cic(icq);
3014 struct cfq_data *cfqd = cic_to_cfqd(cic);
3016 if (cic->cfqq[BLK_RW_ASYNC]) {
3017 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3018 cic->cfqq[BLK_RW_ASYNC] = NULL;
3021 if (cic->cfqq[BLK_RW_SYNC]) {
3022 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3023 cic->cfqq[BLK_RW_SYNC] = NULL;
3027 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3029 struct task_struct *tsk = current;
3032 if (!cfq_cfqq_prio_changed(cfqq))
3035 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3036 switch (ioprio_class) {
3038 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3039 case IOPRIO_CLASS_NONE:
3041 * no prio set, inherit CPU scheduling settings
3043 cfqq->ioprio = task_nice_ioprio(tsk);
3044 cfqq->ioprio_class = task_nice_ioclass(tsk);
3046 case IOPRIO_CLASS_RT:
3047 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3048 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3050 case IOPRIO_CLASS_BE:
3051 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3052 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3054 case IOPRIO_CLASS_IDLE:
3055 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3057 cfq_clear_cfqq_idle_window(cfqq);
3062 * keep track of original prio settings in case we have to temporarily
3063 * elevate the priority of this queue
3065 cfqq->org_ioprio = cfqq->ioprio;
3066 cfq_clear_cfqq_prio_changed(cfqq);
3069 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3071 int ioprio = cic->icq.ioc->ioprio;
3072 struct cfq_data *cfqd = cic_to_cfqd(cic);
3073 struct cfq_queue *cfqq;
3076 * Check whether ioprio has changed. The condition may trigger
3077 * spuriously on a newly created cic but there's no harm.
3079 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3082 cfqq = cic->cfqq[BLK_RW_ASYNC];
3084 struct cfq_queue *new_cfqq;
3085 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3088 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3089 cfq_put_queue(cfqq);
3093 cfqq = cic->cfqq[BLK_RW_SYNC];
3095 cfq_mark_cfqq_prio_changed(cfqq);
3097 cic->ioprio = ioprio;
3100 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3101 pid_t pid, bool is_sync)
3103 RB_CLEAR_NODE(&cfqq->rb_node);
3104 RB_CLEAR_NODE(&cfqq->p_node);
3105 INIT_LIST_HEAD(&cfqq->fifo);
3110 cfq_mark_cfqq_prio_changed(cfqq);
3113 if (!cfq_class_idle(cfqq))
3114 cfq_mark_cfqq_idle_window(cfqq);
3115 cfq_mark_cfqq_sync(cfqq);
3120 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3121 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3123 struct cfq_data *cfqd = cic_to_cfqd(cic);
3124 struct cfq_queue *sync_cfqq;
3128 id = bio_blkio_cgroup(bio)->id;
3132 * Check whether blkcg has changed. The condition may trigger
3133 * spuriously on a newly created cic but there's no harm.
3135 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3138 sync_cfqq = cic_to_cfqq(cic, 1);
3141 * Drop reference to sync queue. A new sync queue will be
3142 * assigned in new group upon arrival of a fresh request.
3144 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3145 cic_set_cfqq(cic, NULL, 1);
3146 cfq_put_queue(sync_cfqq);
3152 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3153 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3155 static struct cfq_queue *
3156 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3157 struct bio *bio, gfp_t gfp_mask)
3159 struct blkio_cgroup *blkcg;
3160 struct cfq_queue *cfqq, *new_cfqq = NULL;
3161 struct cfq_group *cfqg;
3166 blkcg = bio_blkio_cgroup(bio);
3167 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3168 cfqq = cic_to_cfqq(cic, is_sync);
3171 * Always try a new alloc if we fell back to the OOM cfqq
3172 * originally, since it should just be a temporary situation.
3174 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3179 } else if (gfp_mask & __GFP_WAIT) {
3181 spin_unlock_irq(cfqd->queue->queue_lock);
3182 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3183 gfp_mask | __GFP_ZERO,
3185 spin_lock_irq(cfqd->queue->queue_lock);
3189 cfqq = kmem_cache_alloc_node(cfq_pool,
3190 gfp_mask | __GFP_ZERO,
3195 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3196 cfq_init_prio_data(cfqq, cic);
3197 cfq_link_cfqq_cfqg(cfqq, cfqg);
3198 cfq_log_cfqq(cfqd, cfqq, "alloced");
3200 cfqq = &cfqd->oom_cfqq;
3204 kmem_cache_free(cfq_pool, new_cfqq);
3210 static struct cfq_queue **
3211 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3213 switch (ioprio_class) {
3214 case IOPRIO_CLASS_RT:
3215 return &cfqd->async_cfqq[0][ioprio];
3216 case IOPRIO_CLASS_NONE:
3217 ioprio = IOPRIO_NORM;
3219 case IOPRIO_CLASS_BE:
3220 return &cfqd->async_cfqq[1][ioprio];
3221 case IOPRIO_CLASS_IDLE:
3222 return &cfqd->async_idle_cfqq;
3228 static struct cfq_queue *
3229 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3230 struct bio *bio, gfp_t gfp_mask)
3232 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3233 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3234 struct cfq_queue **async_cfqq = NULL;
3235 struct cfq_queue *cfqq = NULL;
3238 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3243 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3246 * pin the queue now that it's allocated, scheduler exit will prune it
3248 if (!is_sync && !(*async_cfqq)) {
3258 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3260 unsigned long elapsed = jiffies - ttime->last_end_request;
3261 elapsed = min(elapsed, 2UL * slice_idle);
3263 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3264 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3265 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3269 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3270 struct cfq_io_cq *cic)
3272 if (cfq_cfqq_sync(cfqq)) {
3273 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3274 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3275 cfqd->cfq_slice_idle);
3277 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3278 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3283 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3287 sector_t n_sec = blk_rq_sectors(rq);
3288 if (cfqq->last_request_pos) {
3289 if (cfqq->last_request_pos < blk_rq_pos(rq))
3290 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3292 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3295 cfqq->seek_history <<= 1;
3296 if (blk_queue_nonrot(cfqd->queue))
3297 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3299 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3303 * Disable idle window if the process thinks too long or seeks so much that
3307 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3308 struct cfq_io_cq *cic)
3310 int old_idle, enable_idle;
3313 * Don't idle for async or idle io prio class
3315 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3318 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3320 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3321 cfq_mark_cfqq_deep(cfqq);
3323 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3325 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3326 !cfqd->cfq_slice_idle ||
3327 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3329 else if (sample_valid(cic->ttime.ttime_samples)) {
3330 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3336 if (old_idle != enable_idle) {
3337 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3339 cfq_mark_cfqq_idle_window(cfqq);
3341 cfq_clear_cfqq_idle_window(cfqq);
3346 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3347 * no or if we aren't sure, a 1 will cause a preempt.
3350 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3353 struct cfq_queue *cfqq;
3355 cfqq = cfqd->active_queue;
3359 if (cfq_class_idle(new_cfqq))
3362 if (cfq_class_idle(cfqq))
3366 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3368 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3372 * if the new request is sync, but the currently running queue is
3373 * not, let the sync request have priority.
3375 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3378 if (new_cfqq->cfqg != cfqq->cfqg)
3381 if (cfq_slice_used(cfqq))
3384 /* Allow preemption only if we are idling on sync-noidle tree */
3385 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3386 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3387 new_cfqq->service_tree->count == 2 &&
3388 RB_EMPTY_ROOT(&cfqq->sort_list))
3392 * So both queues are sync. Let the new request get disk time if
3393 * it's a metadata request and the current queue is doing regular IO.
3395 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3399 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3401 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3404 /* An idle queue should not be idle now for some reason */
3405 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3408 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3412 * if this request is as-good as one we would expect from the
3413 * current cfqq, let it preempt
3415 if (cfq_rq_close(cfqd, cfqq, rq))
3422 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3423 * let it have half of its nominal slice.
3425 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3427 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3429 cfq_log_cfqq(cfqd, cfqq, "preempt");
3430 cfq_slice_expired(cfqd, 1);
3433 * workload type is changed, don't save slice, otherwise preempt
3436 if (old_type != cfqq_type(cfqq))
3437 cfqq->cfqg->saved_workload_slice = 0;
3440 * Put the new queue at the front of the of the current list,
3441 * so we know that it will be selected next.
3443 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3445 cfq_service_tree_add(cfqd, cfqq, 1);
3447 cfqq->slice_end = 0;
3448 cfq_mark_cfqq_slice_new(cfqq);
3452 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3453 * something we should do about it
3456 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3459 struct cfq_io_cq *cic = RQ_CIC(rq);
3462 if (rq->cmd_flags & REQ_PRIO)
3463 cfqq->prio_pending++;
3465 cfq_update_io_thinktime(cfqd, cfqq, cic);
3466 cfq_update_io_seektime(cfqd, cfqq, rq);
3467 cfq_update_idle_window(cfqd, cfqq, cic);
3469 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3471 if (cfqq == cfqd->active_queue) {
3473 * Remember that we saw a request from this process, but
3474 * don't start queuing just yet. Otherwise we risk seeing lots
3475 * of tiny requests, because we disrupt the normal plugging
3476 * and merging. If the request is already larger than a single
3477 * page, let it rip immediately. For that case we assume that
3478 * merging is already done. Ditto for a busy system that
3479 * has other work pending, don't risk delaying until the
3480 * idle timer unplug to continue working.
3482 if (cfq_cfqq_wait_request(cfqq)) {
3483 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3484 cfqd->busy_queues > 1) {
3485 cfq_del_timer(cfqd, cfqq);
3486 cfq_clear_cfqq_wait_request(cfqq);
3487 __blk_run_queue(cfqd->queue);
3489 cfqg_stats_update_idle_time(cfqq->cfqg);
3490 cfq_mark_cfqq_must_dispatch(cfqq);
3493 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3495 * not the active queue - expire current slice if it is
3496 * idle and has expired it's mean thinktime or this new queue
3497 * has some old slice time left and is of higher priority or
3498 * this new queue is RT and the current one is BE
3500 cfq_preempt_queue(cfqd, cfqq);
3501 __blk_run_queue(cfqd->queue);
3505 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3507 struct cfq_data *cfqd = q->elevator->elevator_data;
3508 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3510 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3511 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3513 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3514 list_add_tail(&rq->queuelist, &cfqq->fifo);
3516 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3518 cfq_rq_enqueued(cfqd, cfqq, rq);
3522 * Update hw_tag based on peak queue depth over 50 samples under
3525 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3527 struct cfq_queue *cfqq = cfqd->active_queue;
3529 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3530 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3532 if (cfqd->hw_tag == 1)
3535 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3536 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3540 * If active queue hasn't enough requests and can idle, cfq might not
3541 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3544 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3545 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3546 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3549 if (cfqd->hw_tag_samples++ < 50)
3552 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3558 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3560 struct cfq_io_cq *cic = cfqd->active_cic;
3562 /* If the queue already has requests, don't wait */
3563 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3566 /* If there are other queues in the group, don't wait */
3567 if (cfqq->cfqg->nr_cfqq > 1)
3570 /* the only queue in the group, but think time is big */
3571 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3574 if (cfq_slice_used(cfqq))
3577 /* if slice left is less than think time, wait busy */
3578 if (cic && sample_valid(cic->ttime.ttime_samples)
3579 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3583 * If think times is less than a jiffy than ttime_mean=0 and above
3584 * will not be true. It might happen that slice has not expired yet
3585 * but will expire soon (4-5 ns) during select_queue(). To cover the
3586 * case where think time is less than a jiffy, mark the queue wait
3587 * busy if only 1 jiffy is left in the slice.
3589 if (cfqq->slice_end - jiffies == 1)
3595 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3597 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3598 struct cfq_data *cfqd = cfqq->cfqd;
3599 const int sync = rq_is_sync(rq);
3603 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3604 !!(rq->cmd_flags & REQ_NOIDLE));
3606 cfq_update_hw_tag(cfqd);
3608 WARN_ON(!cfqd->rq_in_driver);
3609 WARN_ON(!cfqq->dispatched);
3610 cfqd->rq_in_driver--;
3612 (RQ_CFQG(rq))->dispatched--;
3613 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3614 rq_io_start_time_ns(rq), rq->cmd_flags);
3616 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3619 struct cfq_rb_root *service_tree;
3621 RQ_CIC(rq)->ttime.last_end_request = now;
3623 if (cfq_cfqq_on_rr(cfqq))
3624 service_tree = cfqq->service_tree;
3626 service_tree = service_tree_for(cfqq->cfqg,
3627 cfqq_prio(cfqq), cfqq_type(cfqq));
3628 service_tree->ttime.last_end_request = now;
3629 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3630 cfqd->last_delayed_sync = now;
3633 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3634 cfqq->cfqg->ttime.last_end_request = now;
3638 * If this is the active queue, check if it needs to be expired,
3639 * or if we want to idle in case it has no pending requests.
3641 if (cfqd->active_queue == cfqq) {
3642 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3644 if (cfq_cfqq_slice_new(cfqq)) {
3645 cfq_set_prio_slice(cfqd, cfqq);
3646 cfq_clear_cfqq_slice_new(cfqq);
3650 * Should we wait for next request to come in before we expire
3653 if (cfq_should_wait_busy(cfqd, cfqq)) {
3654 unsigned long extend_sl = cfqd->cfq_slice_idle;
3655 if (!cfqd->cfq_slice_idle)
3656 extend_sl = cfqd->cfq_group_idle;
3657 cfqq->slice_end = jiffies + extend_sl;
3658 cfq_mark_cfqq_wait_busy(cfqq);
3659 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3663 * Idling is not enabled on:
3665 * - idle-priority queues
3667 * - queues with still some requests queued
3668 * - when there is a close cooperator
3670 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3671 cfq_slice_expired(cfqd, 1);
3672 else if (sync && cfqq_empty &&
3673 !cfq_close_cooperator(cfqd, cfqq)) {
3674 cfq_arm_slice_timer(cfqd);
3678 if (!cfqd->rq_in_driver)
3679 cfq_schedule_dispatch(cfqd);
3682 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3684 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3685 cfq_mark_cfqq_must_alloc_slice(cfqq);
3686 return ELV_MQUEUE_MUST;
3689 return ELV_MQUEUE_MAY;
3692 static int cfq_may_queue(struct request_queue *q, int rw)
3694 struct cfq_data *cfqd = q->elevator->elevator_data;
3695 struct task_struct *tsk = current;
3696 struct cfq_io_cq *cic;
3697 struct cfq_queue *cfqq;
3700 * don't force setup of a queue from here, as a call to may_queue
3701 * does not necessarily imply that a request actually will be queued.
3702 * so just lookup a possibly existing queue, or return 'may queue'
3705 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3707 return ELV_MQUEUE_MAY;
3709 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3711 cfq_init_prio_data(cfqq, cic);
3713 return __cfq_may_queue(cfqq);
3716 return ELV_MQUEUE_MAY;
3720 * queue lock held here
3722 static void cfq_put_request(struct request *rq)
3724 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3727 const int rw = rq_data_dir(rq);
3729 BUG_ON(!cfqq->allocated[rw]);
3730 cfqq->allocated[rw]--;
3732 /* Put down rq reference on cfqg */
3733 cfqg_put(RQ_CFQG(rq));
3734 rq->elv.priv[0] = NULL;
3735 rq->elv.priv[1] = NULL;
3737 cfq_put_queue(cfqq);
3741 static struct cfq_queue *
3742 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3743 struct cfq_queue *cfqq)
3745 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3746 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3747 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3748 cfq_put_queue(cfqq);
3749 return cic_to_cfqq(cic, 1);
3753 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3754 * was the last process referring to said cfqq.
3756 static struct cfq_queue *
3757 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3759 if (cfqq_process_refs(cfqq) == 1) {
3760 cfqq->pid = current->pid;
3761 cfq_clear_cfqq_coop(cfqq);
3762 cfq_clear_cfqq_split_coop(cfqq);
3766 cic_set_cfqq(cic, NULL, 1);
3768 cfq_put_cooperator(cfqq);
3770 cfq_put_queue(cfqq);
3774 * Allocate cfq data structures associated with this request.
3777 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3780 struct cfq_data *cfqd = q->elevator->elevator_data;
3781 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3782 const int rw = rq_data_dir(rq);
3783 const bool is_sync = rq_is_sync(rq);
3784 struct cfq_queue *cfqq;
3786 might_sleep_if(gfp_mask & __GFP_WAIT);
3788 spin_lock_irq(q->queue_lock);
3790 check_ioprio_changed(cic, bio);
3791 check_blkcg_changed(cic, bio);
3793 cfqq = cic_to_cfqq(cic, is_sync);
3794 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3795 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3796 cic_set_cfqq(cic, cfqq, is_sync);
3799 * If the queue was seeky for too long, break it apart.
3801 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3802 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3803 cfqq = split_cfqq(cic, cfqq);
3809 * Check to see if this queue is scheduled to merge with
3810 * another, closely cooperating queue. The merging of
3811 * queues happens here as it must be done in process context.
3812 * The reference on new_cfqq was taken in merge_cfqqs.
3815 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3818 cfqq->allocated[rw]++;
3821 cfqg_get(cfqq->cfqg);
3822 rq->elv.priv[0] = cfqq;
3823 rq->elv.priv[1] = cfqq->cfqg;
3824 spin_unlock_irq(q->queue_lock);
3828 static void cfq_kick_queue(struct work_struct *work)
3830 struct cfq_data *cfqd =
3831 container_of(work, struct cfq_data, unplug_work);
3832 struct request_queue *q = cfqd->queue;
3834 spin_lock_irq(q->queue_lock);
3835 __blk_run_queue(cfqd->queue);
3836 spin_unlock_irq(q->queue_lock);
3840 * Timer running if the active_queue is currently idling inside its time slice
3842 static void cfq_idle_slice_timer(unsigned long data)
3844 struct cfq_data *cfqd = (struct cfq_data *) data;
3845 struct cfq_queue *cfqq;
3846 unsigned long flags;
3849 cfq_log(cfqd, "idle timer fired");
3851 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3853 cfqq = cfqd->active_queue;
3858 * We saw a request before the queue expired, let it through
3860 if (cfq_cfqq_must_dispatch(cfqq))
3866 if (cfq_slice_used(cfqq))
3870 * only expire and reinvoke request handler, if there are
3871 * other queues with pending requests
3873 if (!cfqd->busy_queues)
3877 * not expired and it has a request pending, let it dispatch
3879 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3883 * Queue depth flag is reset only when the idle didn't succeed
3885 cfq_clear_cfqq_deep(cfqq);
3888 cfq_slice_expired(cfqd, timed_out);
3890 cfq_schedule_dispatch(cfqd);
3892 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3895 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3897 del_timer_sync(&cfqd->idle_slice_timer);
3898 cancel_work_sync(&cfqd->unplug_work);
3901 static void cfq_put_async_queues(struct cfq_data *cfqd)
3905 for (i = 0; i < IOPRIO_BE_NR; i++) {
3906 if (cfqd->async_cfqq[0][i])
3907 cfq_put_queue(cfqd->async_cfqq[0][i]);
3908 if (cfqd->async_cfqq[1][i])
3909 cfq_put_queue(cfqd->async_cfqq[1][i]);
3912 if (cfqd->async_idle_cfqq)
3913 cfq_put_queue(cfqd->async_idle_cfqq);
3916 static void cfq_exit_queue(struct elevator_queue *e)
3918 struct cfq_data *cfqd = e->elevator_data;
3919 struct request_queue *q = cfqd->queue;
3921 cfq_shutdown_timer_wq(cfqd);
3923 spin_lock_irq(q->queue_lock);
3925 if (cfqd->active_queue)
3926 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3928 cfq_put_async_queues(cfqd);
3930 spin_unlock_irq(q->queue_lock);
3932 cfq_shutdown_timer_wq(cfqd);
3934 #ifndef CONFIG_CFQ_GROUP_IOSCHED
3935 kfree(cfqd->root_group);
3937 update_root_blkg_pd(q, BLKIO_POLICY_PROP);
3941 static int cfq_init_queue(struct request_queue *q)
3943 struct cfq_data *cfqd;
3944 struct blkio_group *blkg __maybe_unused;
3947 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3952 q->elevator->elevator_data = cfqd;
3954 /* Init root service tree */
3955 cfqd->grp_service_tree = CFQ_RB_ROOT;
3957 /* Init root group and prefer root group over other groups by default */
3958 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3960 spin_lock_irq(q->queue_lock);
3962 blkg = blkg_lookup_create(&blkio_root_cgroup, q, true);
3964 cfqd->root_group = blkg_to_cfqg(blkg);
3966 spin_unlock_irq(q->queue_lock);
3969 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3970 GFP_KERNEL, cfqd->queue->node);
3971 if (cfqd->root_group)
3972 cfq_init_cfqg_base(cfqd->root_group);
3974 if (!cfqd->root_group) {
3979 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3982 * Not strictly needed (since RB_ROOT just clears the node and we
3983 * zeroed cfqd on alloc), but better be safe in case someone decides
3984 * to add magic to the rb code
3986 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3987 cfqd->prio_trees[i] = RB_ROOT;
3990 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3991 * Grab a permanent reference to it, so that the normal code flow
3992 * will not attempt to free it. oom_cfqq is linked to root_group
3993 * but shouldn't hold a reference as it'll never be unlinked. Lose
3994 * the reference from linking right away.
3996 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3997 cfqd->oom_cfqq.ref++;
3999 spin_lock_irq(q->queue_lock);
4000 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4001 cfqg_put(cfqd->root_group);
4002 spin_unlock_irq(q->queue_lock);
4004 init_timer(&cfqd->idle_slice_timer);
4005 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4006 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4008 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4010 cfqd->cfq_quantum = cfq_quantum;
4011 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4012 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4013 cfqd->cfq_back_max = cfq_back_max;
4014 cfqd->cfq_back_penalty = cfq_back_penalty;
4015 cfqd->cfq_slice[0] = cfq_slice_async;
4016 cfqd->cfq_slice[1] = cfq_slice_sync;
4017 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4018 cfqd->cfq_slice_idle = cfq_slice_idle;
4019 cfqd->cfq_group_idle = cfq_group_idle;
4020 cfqd->cfq_latency = 1;
4023 * we optimistically start assuming sync ops weren't delayed in last
4024 * second, in order to have larger depth for async operations.
4026 cfqd->last_delayed_sync = jiffies - HZ;
4031 * sysfs parts below -->
4034 cfq_var_show(unsigned int var, char *page)
4036 return sprintf(page, "%d\n", var);
4040 cfq_var_store(unsigned int *var, const char *page, size_t count)
4042 char *p = (char *) page;
4044 *var = simple_strtoul(p, &p, 10);
4048 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4049 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4051 struct cfq_data *cfqd = e->elevator_data; \
4052 unsigned int __data = __VAR; \
4054 __data = jiffies_to_msecs(__data); \
4055 return cfq_var_show(__data, (page)); \
4057 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4058 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4059 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4060 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4061 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4062 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4063 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4064 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4065 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4066 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4067 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4068 #undef SHOW_FUNCTION
4070 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4071 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4073 struct cfq_data *cfqd = e->elevator_data; \
4074 unsigned int __data; \
4075 int ret = cfq_var_store(&__data, (page), count); \
4076 if (__data < (MIN)) \
4078 else if (__data > (MAX)) \
4081 *(__PTR) = msecs_to_jiffies(__data); \
4083 *(__PTR) = __data; \
4086 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4087 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4089 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4091 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4092 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4094 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4095 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4096 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4097 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4098 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4100 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4101 #undef STORE_FUNCTION
4103 #define CFQ_ATTR(name) \
4104 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4106 static struct elv_fs_entry cfq_attrs[] = {
4108 CFQ_ATTR(fifo_expire_sync),
4109 CFQ_ATTR(fifo_expire_async),
4110 CFQ_ATTR(back_seek_max),
4111 CFQ_ATTR(back_seek_penalty),
4112 CFQ_ATTR(slice_sync),
4113 CFQ_ATTR(slice_async),
4114 CFQ_ATTR(slice_async_rq),
4115 CFQ_ATTR(slice_idle),
4116 CFQ_ATTR(group_idle),
4117 CFQ_ATTR(low_latency),
4121 static struct elevator_type iosched_cfq = {
4123 .elevator_merge_fn = cfq_merge,
4124 .elevator_merged_fn = cfq_merged_request,
4125 .elevator_merge_req_fn = cfq_merged_requests,
4126 .elevator_allow_merge_fn = cfq_allow_merge,
4127 .elevator_bio_merged_fn = cfq_bio_merged,
4128 .elevator_dispatch_fn = cfq_dispatch_requests,
4129 .elevator_add_req_fn = cfq_insert_request,
4130 .elevator_activate_req_fn = cfq_activate_request,
4131 .elevator_deactivate_req_fn = cfq_deactivate_request,
4132 .elevator_completed_req_fn = cfq_completed_request,
4133 .elevator_former_req_fn = elv_rb_former_request,
4134 .elevator_latter_req_fn = elv_rb_latter_request,
4135 .elevator_init_icq_fn = cfq_init_icq,
4136 .elevator_exit_icq_fn = cfq_exit_icq,
4137 .elevator_set_req_fn = cfq_set_request,
4138 .elevator_put_req_fn = cfq_put_request,
4139 .elevator_may_queue_fn = cfq_may_queue,
4140 .elevator_init_fn = cfq_init_queue,
4141 .elevator_exit_fn = cfq_exit_queue,
4143 .icq_size = sizeof(struct cfq_io_cq),
4144 .icq_align = __alignof__(struct cfq_io_cq),
4145 .elevator_attrs = cfq_attrs,
4146 .elevator_name = "cfq",
4147 .elevator_owner = THIS_MODULE,
4150 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4151 static struct blkio_policy_type blkio_policy_cfq = {
4153 .blkio_init_group_fn = cfq_init_blkio_group,
4154 .blkio_reset_group_stats_fn = cfqg_stats_reset,
4156 .plid = BLKIO_POLICY_PROP,
4157 .pdata_size = sizeof(struct cfq_group),
4158 .cftypes = cfq_blkcg_files,
4162 static int __init cfq_init(void)
4167 * could be 0 on HZ < 1000 setups
4169 if (!cfq_slice_async)
4170 cfq_slice_async = 1;
4171 if (!cfq_slice_idle)
4174 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4175 if (!cfq_group_idle)
4180 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4184 ret = elv_register(&iosched_cfq);
4186 kmem_cache_destroy(cfq_pool);
4190 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4191 blkio_policy_register(&blkio_policy_cfq);
4196 static void __exit cfq_exit(void)
4198 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4199 blkio_policy_unregister(&blkio_policy_cfq);
4201 elv_unregister(&iosched_cfq);
4202 kmem_cache_destroy(cfq_pool);
4205 module_init(cfq_init);
4206 module_exit(cfq_exit);
4208 MODULE_AUTHOR("Jens Axboe");
4209 MODULE_LICENSE("GPL");
4210 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");