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 __maybe_unused;
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 inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
545 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
546 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
547 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
548 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
549 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
550 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
552 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
554 #ifdef CONFIG_CFQ_GROUP_IOSCHED
556 static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg)
558 return blkg_to_pdata(blkg, &blkio_policy_cfq);
561 static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg)
563 return pdata_to_blkg(cfqg);
566 static inline void cfqg_get(struct cfq_group *cfqg)
568 return blkg_get(cfqg_to_blkg(cfqg));
571 static inline void cfqg_put(struct cfq_group *cfqg)
573 return blkg_put(cfqg_to_blkg(cfqg));
576 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
577 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
578 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
579 blkg_path(cfqg_to_blkg((cfqq)->cfqg)), ##args)
581 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
582 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
583 blkg_path(cfqg_to_blkg((cfqg))), ##args) \
585 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
586 struct cfq_group *curr_cfqg, int rw)
588 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
589 cfqg_stats_end_empty_time(&cfqg->stats);
590 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
593 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
594 unsigned long time, unsigned long unaccounted_time)
596 blkg_stat_add(&cfqg->stats.time, time);
597 #ifdef CONFIG_DEBUG_BLK_CGROUP
598 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
602 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
604 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
607 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
609 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
612 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
613 uint64_t bytes, int rw)
615 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
616 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
617 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
620 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
621 uint64_t start_time, uint64_t io_start_time, int rw)
623 struct cfqg_stats *stats = &cfqg->stats;
624 unsigned long long now = sched_clock();
626 if (time_after64(now, io_start_time))
627 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
628 if (time_after64(io_start_time, start_time))
629 blkg_rwstat_add(&stats->wait_time, rw,
630 io_start_time - start_time);
633 static void cfqg_stats_reset(struct blkio_group *blkg)
635 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
636 struct cfqg_stats *stats = &cfqg->stats;
638 /* queued stats shouldn't be cleared */
639 blkg_rwstat_reset(&stats->service_bytes);
640 blkg_rwstat_reset(&stats->serviced);
641 blkg_rwstat_reset(&stats->merged);
642 blkg_rwstat_reset(&stats->service_time);
643 blkg_rwstat_reset(&stats->wait_time);
644 blkg_stat_reset(&stats->time);
645 #ifdef CONFIG_DEBUG_BLK_CGROUP
646 blkg_stat_reset(&stats->unaccounted_time);
647 blkg_stat_reset(&stats->avg_queue_size_sum);
648 blkg_stat_reset(&stats->avg_queue_size_samples);
649 blkg_stat_reset(&stats->dequeue);
650 blkg_stat_reset(&stats->group_wait_time);
651 blkg_stat_reset(&stats->idle_time);
652 blkg_stat_reset(&stats->empty_time);
656 #else /* CONFIG_CFQ_GROUP_IOSCHED */
658 static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg) { return NULL; }
659 static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg) { return NULL; }
660 static inline void cfqg_get(struct cfq_group *cfqg) { }
661 static inline void cfqg_put(struct cfq_group *cfqg) { }
663 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
664 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
665 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
667 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
668 struct cfq_group *curr_cfqg, int rw) { }
669 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
670 unsigned long time, unsigned long unaccounted_time) { }
671 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
672 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
673 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
674 uint64_t bytes, int rw) { }
675 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
676 uint64_t start_time, uint64_t io_start_time, int rw) { }
678 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
680 #define cfq_log(cfqd, fmt, args...) \
681 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
683 /* Traverses through cfq group service trees */
684 #define for_each_cfqg_st(cfqg, i, j, st) \
685 for (i = 0; i <= IDLE_WORKLOAD; i++) \
686 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
687 : &cfqg->service_tree_idle; \
688 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
689 (i == IDLE_WORKLOAD && j == 0); \
690 j++, st = i < IDLE_WORKLOAD ? \
691 &cfqg->service_trees[i][j]: NULL) \
693 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
694 struct cfq_ttime *ttime, bool group_idle)
697 if (!sample_valid(ttime->ttime_samples))
700 slice = cfqd->cfq_group_idle;
702 slice = cfqd->cfq_slice_idle;
703 return ttime->ttime_mean > slice;
706 static inline bool iops_mode(struct cfq_data *cfqd)
709 * If we are not idling on queues and it is a NCQ drive, parallel
710 * execution of requests is on and measuring time is not possible
711 * in most of the cases until and unless we drive shallower queue
712 * depths and that becomes a performance bottleneck. In such cases
713 * switch to start providing fairness in terms of number of IOs.
715 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
721 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
723 if (cfq_class_idle(cfqq))
724 return IDLE_WORKLOAD;
725 if (cfq_class_rt(cfqq))
731 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
733 if (!cfq_cfqq_sync(cfqq))
734 return ASYNC_WORKLOAD;
735 if (!cfq_cfqq_idle_window(cfqq))
736 return SYNC_NOIDLE_WORKLOAD;
737 return SYNC_WORKLOAD;
740 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
741 struct cfq_data *cfqd,
742 struct cfq_group *cfqg)
744 if (wl == IDLE_WORKLOAD)
745 return cfqg->service_tree_idle.count;
747 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
748 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
749 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
752 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
753 struct cfq_group *cfqg)
755 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
756 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
759 static void cfq_dispatch_insert(struct request_queue *, struct request *);
760 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
761 struct cfq_io_cq *cic, struct bio *bio,
764 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
766 /* cic->icq is the first member, %NULL will convert to %NULL */
767 return container_of(icq, struct cfq_io_cq, icq);
770 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
771 struct io_context *ioc)
774 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
778 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
780 return cic->cfqq[is_sync];
783 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
786 cic->cfqq[is_sync] = cfqq;
789 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
791 return cic->icq.q->elevator->elevator_data;
795 * We regard a request as SYNC, if it's either a read or has the SYNC bit
796 * set (in which case it could also be direct WRITE).
798 static inline bool cfq_bio_sync(struct bio *bio)
800 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
804 * scheduler run of queue, if there are requests pending and no one in the
805 * driver that will restart queueing
807 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
809 if (cfqd->busy_queues) {
810 cfq_log(cfqd, "schedule dispatch");
811 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
816 * Scale schedule slice based on io priority. Use the sync time slice only
817 * if a queue is marked sync and has sync io queued. A sync queue with async
818 * io only, should not get full sync slice length.
820 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
823 const int base_slice = cfqd->cfq_slice[sync];
825 WARN_ON(prio >= IOPRIO_BE_NR);
827 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
831 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
833 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
836 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
838 u64 d = delta << CFQ_SERVICE_SHIFT;
840 d = d * CFQ_WEIGHT_DEFAULT;
841 do_div(d, cfqg->weight);
845 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
847 s64 delta = (s64)(vdisktime - min_vdisktime);
849 min_vdisktime = vdisktime;
851 return min_vdisktime;
854 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
856 s64 delta = (s64)(vdisktime - min_vdisktime);
858 min_vdisktime = vdisktime;
860 return min_vdisktime;
863 static void update_min_vdisktime(struct cfq_rb_root *st)
865 struct cfq_group *cfqg;
868 cfqg = rb_entry_cfqg(st->left);
869 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
875 * get averaged number of queues of RT/BE priority.
876 * average is updated, with a formula that gives more weight to higher numbers,
877 * to quickly follows sudden increases and decrease slowly
880 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
881 struct cfq_group *cfqg, bool rt)
883 unsigned min_q, max_q;
884 unsigned mult = cfq_hist_divisor - 1;
885 unsigned round = cfq_hist_divisor / 2;
886 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
888 min_q = min(cfqg->busy_queues_avg[rt], busy);
889 max_q = max(cfqg->busy_queues_avg[rt], busy);
890 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
892 return cfqg->busy_queues_avg[rt];
895 static inline unsigned
896 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
898 struct cfq_rb_root *st = &cfqd->grp_service_tree;
900 return cfq_target_latency * cfqg->weight / st->total_weight;
903 static inline unsigned
904 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
906 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
907 if (cfqd->cfq_latency) {
909 * interested queues (we consider only the ones with the same
910 * priority class in the cfq group)
912 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
914 unsigned sync_slice = cfqd->cfq_slice[1];
915 unsigned expect_latency = sync_slice * iq;
916 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
918 if (expect_latency > group_slice) {
919 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
920 /* scale low_slice according to IO priority
921 * and sync vs async */
923 min(slice, base_low_slice * slice / sync_slice);
924 /* the adapted slice value is scaled to fit all iqs
925 * into the target latency */
926 slice = max(slice * group_slice / expect_latency,
934 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
936 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
938 cfqq->slice_start = jiffies;
939 cfqq->slice_end = jiffies + slice;
940 cfqq->allocated_slice = slice;
941 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
945 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
946 * isn't valid until the first request from the dispatch is activated
947 * and the slice time set.
949 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
951 if (cfq_cfqq_slice_new(cfqq))
953 if (time_before(jiffies, cfqq->slice_end))
960 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
961 * We choose the request that is closest to the head right now. Distance
962 * behind the head is penalized and only allowed to a certain extent.
964 static struct request *
965 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
967 sector_t s1, s2, d1 = 0, d2 = 0;
968 unsigned long back_max;
969 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
970 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
971 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
973 if (rq1 == NULL || rq1 == rq2)
978 if (rq_is_sync(rq1) != rq_is_sync(rq2))
979 return rq_is_sync(rq1) ? rq1 : rq2;
981 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
982 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
984 s1 = blk_rq_pos(rq1);
985 s2 = blk_rq_pos(rq2);
988 * by definition, 1KiB is 2 sectors
990 back_max = cfqd->cfq_back_max * 2;
993 * Strict one way elevator _except_ in the case where we allow
994 * short backward seeks which are biased as twice the cost of a
995 * similar forward seek.
999 else if (s1 + back_max >= last)
1000 d1 = (last - s1) * cfqd->cfq_back_penalty;
1002 wrap |= CFQ_RQ1_WRAP;
1006 else if (s2 + back_max >= last)
1007 d2 = (last - s2) * cfqd->cfq_back_penalty;
1009 wrap |= CFQ_RQ2_WRAP;
1011 /* Found required data */
1014 * By doing switch() on the bit mask "wrap" we avoid having to
1015 * check two variables for all permutations: --> faster!
1018 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1034 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1037 * Since both rqs are wrapped,
1038 * start with the one that's further behind head
1039 * (--> only *one* back seek required),
1040 * since back seek takes more time than forward.
1050 * The below is leftmost cache rbtree addon
1052 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1054 /* Service tree is empty */
1059 root->left = rb_first(&root->rb);
1062 return rb_entry(root->left, struct cfq_queue, rb_node);
1067 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1070 root->left = rb_first(&root->rb);
1073 return rb_entry_cfqg(root->left);
1078 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1084 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1086 if (root->left == n)
1088 rb_erase_init(n, &root->rb);
1093 * would be nice to take fifo expire time into account as well
1095 static struct request *
1096 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1097 struct request *last)
1099 struct rb_node *rbnext = rb_next(&last->rb_node);
1100 struct rb_node *rbprev = rb_prev(&last->rb_node);
1101 struct request *next = NULL, *prev = NULL;
1103 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1106 prev = rb_entry_rq(rbprev);
1109 next = rb_entry_rq(rbnext);
1111 rbnext = rb_first(&cfqq->sort_list);
1112 if (rbnext && rbnext != &last->rb_node)
1113 next = rb_entry_rq(rbnext);
1116 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1119 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1120 struct cfq_queue *cfqq)
1123 * just an approximation, should be ok.
1125 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1126 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1130 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1132 return cfqg->vdisktime - st->min_vdisktime;
1136 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1138 struct rb_node **node = &st->rb.rb_node;
1139 struct rb_node *parent = NULL;
1140 struct cfq_group *__cfqg;
1141 s64 key = cfqg_key(st, cfqg);
1144 while (*node != NULL) {
1146 __cfqg = rb_entry_cfqg(parent);
1148 if (key < cfqg_key(st, __cfqg))
1149 node = &parent->rb_left;
1151 node = &parent->rb_right;
1157 st->left = &cfqg->rb_node;
1159 rb_link_node(&cfqg->rb_node, parent, node);
1160 rb_insert_color(&cfqg->rb_node, &st->rb);
1164 cfq_update_group_weight(struct cfq_group *cfqg)
1166 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1167 if (cfqg->new_weight) {
1168 cfqg->weight = cfqg->new_weight;
1169 cfqg->new_weight = 0;
1174 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1176 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1178 cfq_update_group_weight(cfqg);
1179 __cfq_group_service_tree_add(st, cfqg);
1180 st->total_weight += cfqg->weight;
1184 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1186 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1187 struct cfq_group *__cfqg;
1191 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1195 * Currently put the group at the end. Later implement something
1196 * so that groups get lesser vtime based on their weights, so that
1197 * if group does not loose all if it was not continuously backlogged.
1199 n = rb_last(&st->rb);
1201 __cfqg = rb_entry_cfqg(n);
1202 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1204 cfqg->vdisktime = st->min_vdisktime;
1205 cfq_group_service_tree_add(st, cfqg);
1209 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1211 st->total_weight -= cfqg->weight;
1212 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1213 cfq_rb_erase(&cfqg->rb_node, st);
1217 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1219 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1221 BUG_ON(cfqg->nr_cfqq < 1);
1224 /* If there are other cfq queues under this group, don't delete it */
1228 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1229 cfq_group_service_tree_del(st, cfqg);
1230 cfqg->saved_workload_slice = 0;
1231 cfqg_stats_update_dequeue(cfqg);
1234 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1235 unsigned int *unaccounted_time)
1237 unsigned int slice_used;
1240 * Queue got expired before even a single request completed or
1241 * got expired immediately after first request completion.
1243 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1245 * Also charge the seek time incurred to the group, otherwise
1246 * if there are mutiple queues in the group, each can dispatch
1247 * a single request on seeky media and cause lots of seek time
1248 * and group will never know it.
1250 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1253 slice_used = jiffies - cfqq->slice_start;
1254 if (slice_used > cfqq->allocated_slice) {
1255 *unaccounted_time = slice_used - cfqq->allocated_slice;
1256 slice_used = cfqq->allocated_slice;
1258 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1259 *unaccounted_time += cfqq->slice_start -
1260 cfqq->dispatch_start;
1266 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1267 struct cfq_queue *cfqq)
1269 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1270 unsigned int used_sl, charge, unaccounted_sl = 0;
1271 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1272 - cfqg->service_tree_idle.count;
1274 BUG_ON(nr_sync < 0);
1275 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1277 if (iops_mode(cfqd))
1278 charge = cfqq->slice_dispatch;
1279 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1280 charge = cfqq->allocated_slice;
1282 /* Can't update vdisktime while group is on service tree */
1283 cfq_group_service_tree_del(st, cfqg);
1284 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1285 /* If a new weight was requested, update now, off tree */
1286 cfq_group_service_tree_add(st, cfqg);
1288 /* This group is being expired. Save the context */
1289 if (time_after(cfqd->workload_expires, jiffies)) {
1290 cfqg->saved_workload_slice = cfqd->workload_expires
1292 cfqg->saved_workload = cfqd->serving_type;
1293 cfqg->saved_serving_prio = cfqd->serving_prio;
1295 cfqg->saved_workload_slice = 0;
1297 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1299 cfq_log_cfqq(cfqq->cfqd, cfqq,
1300 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1301 used_sl, cfqq->slice_dispatch, charge,
1302 iops_mode(cfqd), cfqq->nr_sectors);
1303 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1304 cfqg_stats_set_start_empty_time(cfqg);
1308 * cfq_init_cfqg_base - initialize base part of a cfq_group
1309 * @cfqg: cfq_group to initialize
1311 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1312 * is enabled or not.
1314 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1316 struct cfq_rb_root *st;
1319 for_each_cfqg_st(cfqg, i, j, st)
1321 RB_CLEAR_NODE(&cfqg->rb_node);
1323 cfqg->ttime.last_end_request = jiffies;
1326 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1327 static void cfq_init_blkio_group(struct blkio_group *blkg)
1329 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1331 cfq_init_cfqg_base(cfqg);
1332 cfqg->weight = blkg->blkcg->cfq_weight;
1336 * Search for the cfq group current task belongs to. request_queue lock must
1339 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1340 struct blkio_cgroup *blkcg)
1342 struct request_queue *q = cfqd->queue;
1343 struct cfq_group *cfqg = NULL;
1345 /* avoid lookup for the common case where there's no blkio cgroup */
1346 if (blkcg == &blkio_root_cgroup) {
1347 cfqg = cfqd->root_group;
1349 struct blkio_group *blkg;
1351 blkg = blkg_lookup_create(blkcg, q, false);
1353 cfqg = blkg_to_cfqg(blkg);
1359 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1361 /* Currently, all async queues are mapped to root group */
1362 if (!cfq_cfqq_sync(cfqq))
1363 cfqg = cfqq->cfqd->root_group;
1366 /* cfqq reference on cfqg */
1370 static u64 cfqg_prfill_weight_device(struct seq_file *sf, void *pdata, int off)
1372 struct cfq_group *cfqg = pdata;
1374 if (!cfqg->dev_weight)
1376 return __blkg_prfill_u64(sf, pdata, cfqg->dev_weight);
1379 static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1380 struct seq_file *sf)
1382 blkcg_print_blkgs(sf, cgroup_to_blkio_cgroup(cgrp),
1383 cfqg_prfill_weight_device, &blkio_policy_cfq, 0,
1388 static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1389 struct seq_file *sf)
1391 seq_printf(sf, "%u\n", cgroup_to_blkio_cgroup(cgrp)->cfq_weight);
1395 static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1398 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1399 struct blkg_conf_ctx ctx;
1400 struct cfq_group *cfqg;
1403 ret = blkg_conf_prep(blkcg, buf, &ctx);
1408 cfqg = blkg_to_cfqg(ctx.blkg);
1409 if (cfqg && (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN &&
1410 ctx.v <= CFQ_WEIGHT_MAX))) {
1411 cfqg->dev_weight = ctx.v;
1412 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1416 blkg_conf_finish(&ctx);
1420 static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1422 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1423 struct blkio_group *blkg;
1424 struct hlist_node *n;
1426 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1429 spin_lock_irq(&blkcg->lock);
1430 blkcg->cfq_weight = (unsigned int)val;
1432 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1433 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1435 if (cfqg && !cfqg->dev_weight)
1436 cfqg->new_weight = blkcg->cfq_weight;
1439 spin_unlock_irq(&blkcg->lock);
1443 static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
1444 struct seq_file *sf)
1446 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1448 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkio_policy_cfq,
1449 cft->private, false);
1453 static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
1454 struct seq_file *sf)
1456 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1458 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkio_policy_cfq,
1459 cft->private, true);
1463 #ifdef CONFIG_DEBUG_BLK_CGROUP
1464 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, void *pdata, int off)
1466 struct cfq_group *cfqg = pdata;
1467 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1471 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1474 __blkg_prfill_u64(sf, pdata, v);
1478 /* print avg_queue_size */
1479 static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1480 struct seq_file *sf)
1482 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
1484 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1485 &blkio_policy_cfq, 0, false);
1488 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1490 static struct cftype cfq_blkcg_files[] = {
1492 .name = "weight_device",
1493 .read_seq_string = cfqg_print_weight_device,
1494 .write_string = cfqg_set_weight_device,
1495 .max_write_len = 256,
1499 .read_seq_string = cfq_print_weight,
1500 .write_u64 = cfq_set_weight,
1504 .private = offsetof(struct cfq_group, stats.time),
1505 .read_seq_string = cfqg_print_stat,
1509 .private = offsetof(struct cfq_group, stats.sectors),
1510 .read_seq_string = cfqg_print_stat,
1513 .name = "io_service_bytes",
1514 .private = offsetof(struct cfq_group, stats.service_bytes),
1515 .read_seq_string = cfqg_print_rwstat,
1518 .name = "io_serviced",
1519 .private = offsetof(struct cfq_group, stats.serviced),
1520 .read_seq_string = cfqg_print_rwstat,
1523 .name = "io_service_time",
1524 .private = offsetof(struct cfq_group, stats.service_time),
1525 .read_seq_string = cfqg_print_rwstat,
1528 .name = "io_wait_time",
1529 .private = offsetof(struct cfq_group, stats.wait_time),
1530 .read_seq_string = cfqg_print_rwstat,
1533 .name = "io_merged",
1534 .private = offsetof(struct cfq_group, stats.merged),
1535 .read_seq_string = cfqg_print_rwstat,
1538 .name = "io_queued",
1539 .private = offsetof(struct cfq_group, stats.queued),
1540 .read_seq_string = cfqg_print_rwstat,
1542 #ifdef CONFIG_DEBUG_BLK_CGROUP
1544 .name = "avg_queue_size",
1545 .read_seq_string = cfqg_print_avg_queue_size,
1548 .name = "group_wait_time",
1549 .private = offsetof(struct cfq_group, stats.group_wait_time),
1550 .read_seq_string = cfqg_print_stat,
1553 .name = "idle_time",
1554 .private = offsetof(struct cfq_group, stats.idle_time),
1555 .read_seq_string = cfqg_print_stat,
1558 .name = "empty_time",
1559 .private = offsetof(struct cfq_group, stats.empty_time),
1560 .read_seq_string = cfqg_print_stat,
1564 .private = offsetof(struct cfq_group, stats.dequeue),
1565 .read_seq_string = cfqg_print_stat,
1568 .name = "unaccounted_time",
1569 .private = offsetof(struct cfq_group, stats.unaccounted_time),
1570 .read_seq_string = cfqg_print_stat,
1572 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1575 #else /* GROUP_IOSCHED */
1576 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1577 struct blkio_cgroup *blkcg)
1579 return cfqd->root_group;
1583 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1587 #endif /* GROUP_IOSCHED */
1590 * The cfqd->service_trees holds all pending cfq_queue's that have
1591 * requests waiting to be processed. It is sorted in the order that
1592 * we will service the queues.
1594 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1597 struct rb_node **p, *parent;
1598 struct cfq_queue *__cfqq;
1599 unsigned long rb_key;
1600 struct cfq_rb_root *service_tree;
1604 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1606 if (cfq_class_idle(cfqq)) {
1607 rb_key = CFQ_IDLE_DELAY;
1608 parent = rb_last(&service_tree->rb);
1609 if (parent && parent != &cfqq->rb_node) {
1610 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1611 rb_key += __cfqq->rb_key;
1614 } else if (!add_front) {
1616 * Get our rb key offset. Subtract any residual slice
1617 * value carried from last service. A negative resid
1618 * count indicates slice overrun, and this should position
1619 * the next service time further away in the tree.
1621 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1622 rb_key -= cfqq->slice_resid;
1623 cfqq->slice_resid = 0;
1626 __cfqq = cfq_rb_first(service_tree);
1627 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1630 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1633 * same position, nothing more to do
1635 if (rb_key == cfqq->rb_key &&
1636 cfqq->service_tree == service_tree)
1639 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1640 cfqq->service_tree = NULL;
1645 cfqq->service_tree = service_tree;
1646 p = &service_tree->rb.rb_node;
1651 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1654 * sort by key, that represents service time.
1656 if (time_before(rb_key, __cfqq->rb_key))
1659 n = &(*p)->rb_right;
1667 service_tree->left = &cfqq->rb_node;
1669 cfqq->rb_key = rb_key;
1670 rb_link_node(&cfqq->rb_node, parent, p);
1671 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1672 service_tree->count++;
1673 if (add_front || !new_cfqq)
1675 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1678 static struct cfq_queue *
1679 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1680 sector_t sector, struct rb_node **ret_parent,
1681 struct rb_node ***rb_link)
1683 struct rb_node **p, *parent;
1684 struct cfq_queue *cfqq = NULL;
1692 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1695 * Sort strictly based on sector. Smallest to the left,
1696 * largest to the right.
1698 if (sector > blk_rq_pos(cfqq->next_rq))
1699 n = &(*p)->rb_right;
1700 else if (sector < blk_rq_pos(cfqq->next_rq))
1708 *ret_parent = parent;
1714 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1716 struct rb_node **p, *parent;
1717 struct cfq_queue *__cfqq;
1720 rb_erase(&cfqq->p_node, cfqq->p_root);
1721 cfqq->p_root = NULL;
1724 if (cfq_class_idle(cfqq))
1729 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1730 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1731 blk_rq_pos(cfqq->next_rq), &parent, &p);
1733 rb_link_node(&cfqq->p_node, parent, p);
1734 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1736 cfqq->p_root = NULL;
1740 * Update cfqq's position in the service tree.
1742 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1745 * Resorting requires the cfqq to be on the RR list already.
1747 if (cfq_cfqq_on_rr(cfqq)) {
1748 cfq_service_tree_add(cfqd, cfqq, 0);
1749 cfq_prio_tree_add(cfqd, cfqq);
1754 * add to busy list of queues for service, trying to be fair in ordering
1755 * the pending list according to last request service
1757 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1759 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1760 BUG_ON(cfq_cfqq_on_rr(cfqq));
1761 cfq_mark_cfqq_on_rr(cfqq);
1762 cfqd->busy_queues++;
1763 if (cfq_cfqq_sync(cfqq))
1764 cfqd->busy_sync_queues++;
1766 cfq_resort_rr_list(cfqd, cfqq);
1770 * Called when the cfqq no longer has requests pending, remove it from
1773 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1775 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1776 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1777 cfq_clear_cfqq_on_rr(cfqq);
1779 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1780 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1781 cfqq->service_tree = NULL;
1784 rb_erase(&cfqq->p_node, cfqq->p_root);
1785 cfqq->p_root = NULL;
1788 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1789 BUG_ON(!cfqd->busy_queues);
1790 cfqd->busy_queues--;
1791 if (cfq_cfqq_sync(cfqq))
1792 cfqd->busy_sync_queues--;
1796 * rb tree support functions
1798 static void cfq_del_rq_rb(struct request *rq)
1800 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1801 const int sync = rq_is_sync(rq);
1803 BUG_ON(!cfqq->queued[sync]);
1804 cfqq->queued[sync]--;
1806 elv_rb_del(&cfqq->sort_list, rq);
1808 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1810 * Queue will be deleted from service tree when we actually
1811 * expire it later. Right now just remove it from prio tree
1815 rb_erase(&cfqq->p_node, cfqq->p_root);
1816 cfqq->p_root = NULL;
1821 static void cfq_add_rq_rb(struct request *rq)
1823 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1824 struct cfq_data *cfqd = cfqq->cfqd;
1825 struct request *prev;
1827 cfqq->queued[rq_is_sync(rq)]++;
1829 elv_rb_add(&cfqq->sort_list, rq);
1831 if (!cfq_cfqq_on_rr(cfqq))
1832 cfq_add_cfqq_rr(cfqd, cfqq);
1835 * check if this request is a better next-serve candidate
1837 prev = cfqq->next_rq;
1838 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1841 * adjust priority tree position, if ->next_rq changes
1843 if (prev != cfqq->next_rq)
1844 cfq_prio_tree_add(cfqd, cfqq);
1846 BUG_ON(!cfqq->next_rq);
1849 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1851 elv_rb_del(&cfqq->sort_list, rq);
1852 cfqq->queued[rq_is_sync(rq)]--;
1853 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1855 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1859 static struct request *
1860 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1862 struct task_struct *tsk = current;
1863 struct cfq_io_cq *cic;
1864 struct cfq_queue *cfqq;
1866 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1870 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1872 sector_t sector = bio->bi_sector + bio_sectors(bio);
1874 return elv_rb_find(&cfqq->sort_list, sector);
1880 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1882 struct cfq_data *cfqd = q->elevator->elevator_data;
1884 cfqd->rq_in_driver++;
1885 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1886 cfqd->rq_in_driver);
1888 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1891 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1893 struct cfq_data *cfqd = q->elevator->elevator_data;
1895 WARN_ON(!cfqd->rq_in_driver);
1896 cfqd->rq_in_driver--;
1897 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1898 cfqd->rq_in_driver);
1901 static void cfq_remove_request(struct request *rq)
1903 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1905 if (cfqq->next_rq == rq)
1906 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1908 list_del_init(&rq->queuelist);
1911 cfqq->cfqd->rq_queued--;
1912 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1913 if (rq->cmd_flags & REQ_PRIO) {
1914 WARN_ON(!cfqq->prio_pending);
1915 cfqq->prio_pending--;
1919 static int cfq_merge(struct request_queue *q, struct request **req,
1922 struct cfq_data *cfqd = q->elevator->elevator_data;
1923 struct request *__rq;
1925 __rq = cfq_find_rq_fmerge(cfqd, bio);
1926 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1928 return ELEVATOR_FRONT_MERGE;
1931 return ELEVATOR_NO_MERGE;
1934 static void cfq_merged_request(struct request_queue *q, struct request *req,
1937 if (type == ELEVATOR_FRONT_MERGE) {
1938 struct cfq_queue *cfqq = RQ_CFQQ(req);
1940 cfq_reposition_rq_rb(cfqq, req);
1944 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1947 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1951 cfq_merged_requests(struct request_queue *q, struct request *rq,
1952 struct request *next)
1954 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1955 struct cfq_data *cfqd = q->elevator->elevator_data;
1958 * reposition in fifo if next is older than rq
1960 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1961 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1962 list_move(&rq->queuelist, &next->queuelist);
1963 rq_set_fifo_time(rq, rq_fifo_time(next));
1966 if (cfqq->next_rq == next)
1968 cfq_remove_request(next);
1969 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1971 cfqq = RQ_CFQQ(next);
1973 * all requests of this queue are merged to other queues, delete it
1974 * from the service tree. If it's the active_queue,
1975 * cfq_dispatch_requests() will choose to expire it or do idle
1977 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1978 cfqq != cfqd->active_queue)
1979 cfq_del_cfqq_rr(cfqd, cfqq);
1982 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1985 struct cfq_data *cfqd = q->elevator->elevator_data;
1986 struct cfq_io_cq *cic;
1987 struct cfq_queue *cfqq;
1990 * Disallow merge of a sync bio into an async request.
1992 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1996 * Lookup the cfqq that this bio will be queued with and allow
1997 * merge only if rq is queued there.
1999 cic = cfq_cic_lookup(cfqd, current->io_context);
2003 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2004 return cfqq == RQ_CFQQ(rq);
2007 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2009 del_timer(&cfqd->idle_slice_timer);
2010 cfqg_stats_update_idle_time(cfqq->cfqg);
2013 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2014 struct cfq_queue *cfqq)
2017 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
2018 cfqd->serving_prio, cfqd->serving_type);
2019 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2020 cfqq->slice_start = 0;
2021 cfqq->dispatch_start = jiffies;
2022 cfqq->allocated_slice = 0;
2023 cfqq->slice_end = 0;
2024 cfqq->slice_dispatch = 0;
2025 cfqq->nr_sectors = 0;
2027 cfq_clear_cfqq_wait_request(cfqq);
2028 cfq_clear_cfqq_must_dispatch(cfqq);
2029 cfq_clear_cfqq_must_alloc_slice(cfqq);
2030 cfq_clear_cfqq_fifo_expire(cfqq);
2031 cfq_mark_cfqq_slice_new(cfqq);
2033 cfq_del_timer(cfqd, cfqq);
2036 cfqd->active_queue = cfqq;
2040 * current cfqq expired its slice (or was too idle), select new one
2043 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2046 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2048 if (cfq_cfqq_wait_request(cfqq))
2049 cfq_del_timer(cfqd, cfqq);
2051 cfq_clear_cfqq_wait_request(cfqq);
2052 cfq_clear_cfqq_wait_busy(cfqq);
2055 * If this cfqq is shared between multiple processes, check to
2056 * make sure that those processes are still issuing I/Os within
2057 * the mean seek distance. If not, it may be time to break the
2058 * queues apart again.
2060 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2061 cfq_mark_cfqq_split_coop(cfqq);
2064 * store what was left of this slice, if the queue idled/timed out
2067 if (cfq_cfqq_slice_new(cfqq))
2068 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2070 cfqq->slice_resid = cfqq->slice_end - jiffies;
2071 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2074 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2076 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2077 cfq_del_cfqq_rr(cfqd, cfqq);
2079 cfq_resort_rr_list(cfqd, cfqq);
2081 if (cfqq == cfqd->active_queue)
2082 cfqd->active_queue = NULL;
2084 if (cfqd->active_cic) {
2085 put_io_context(cfqd->active_cic->icq.ioc);
2086 cfqd->active_cic = NULL;
2090 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2092 struct cfq_queue *cfqq = cfqd->active_queue;
2095 __cfq_slice_expired(cfqd, cfqq, timed_out);
2099 * Get next queue for service. Unless we have a queue preemption,
2100 * we'll simply select the first cfqq in the service tree.
2102 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2104 struct cfq_rb_root *service_tree =
2105 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
2106 cfqd->serving_type);
2108 if (!cfqd->rq_queued)
2111 /* There is nothing to dispatch */
2114 if (RB_EMPTY_ROOT(&service_tree->rb))
2116 return cfq_rb_first(service_tree);
2119 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2121 struct cfq_group *cfqg;
2122 struct cfq_queue *cfqq;
2124 struct cfq_rb_root *st;
2126 if (!cfqd->rq_queued)
2129 cfqg = cfq_get_next_cfqg(cfqd);
2133 for_each_cfqg_st(cfqg, i, j, st)
2134 if ((cfqq = cfq_rb_first(st)) != NULL)
2140 * Get and set a new active queue for service.
2142 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2143 struct cfq_queue *cfqq)
2146 cfqq = cfq_get_next_queue(cfqd);
2148 __cfq_set_active_queue(cfqd, cfqq);
2152 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2155 if (blk_rq_pos(rq) >= cfqd->last_position)
2156 return blk_rq_pos(rq) - cfqd->last_position;
2158 return cfqd->last_position - blk_rq_pos(rq);
2161 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2164 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2167 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2168 struct cfq_queue *cur_cfqq)
2170 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2171 struct rb_node *parent, *node;
2172 struct cfq_queue *__cfqq;
2173 sector_t sector = cfqd->last_position;
2175 if (RB_EMPTY_ROOT(root))
2179 * First, if we find a request starting at the end of the last
2180 * request, choose it.
2182 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2187 * If the exact sector wasn't found, the parent of the NULL leaf
2188 * will contain the closest sector.
2190 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2191 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2194 if (blk_rq_pos(__cfqq->next_rq) < sector)
2195 node = rb_next(&__cfqq->p_node);
2197 node = rb_prev(&__cfqq->p_node);
2201 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2202 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2210 * cur_cfqq - passed in so that we don't decide that the current queue is
2211 * closely cooperating with itself.
2213 * So, basically we're assuming that that cur_cfqq has dispatched at least
2214 * one request, and that cfqd->last_position reflects a position on the disk
2215 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2218 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2219 struct cfq_queue *cur_cfqq)
2221 struct cfq_queue *cfqq;
2223 if (cfq_class_idle(cur_cfqq))
2225 if (!cfq_cfqq_sync(cur_cfqq))
2227 if (CFQQ_SEEKY(cur_cfqq))
2231 * Don't search priority tree if it's the only queue in the group.
2233 if (cur_cfqq->cfqg->nr_cfqq == 1)
2237 * We should notice if some of the queues are cooperating, eg
2238 * working closely on the same area of the disk. In that case,
2239 * we can group them together and don't waste time idling.
2241 cfqq = cfqq_close(cfqd, cur_cfqq);
2245 /* If new queue belongs to different cfq_group, don't choose it */
2246 if (cur_cfqq->cfqg != cfqq->cfqg)
2250 * It only makes sense to merge sync queues.
2252 if (!cfq_cfqq_sync(cfqq))
2254 if (CFQQ_SEEKY(cfqq))
2258 * Do not merge queues of different priority classes
2260 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2267 * Determine whether we should enforce idle window for this queue.
2270 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2272 enum wl_prio_t prio = cfqq_prio(cfqq);
2273 struct cfq_rb_root *service_tree = cfqq->service_tree;
2275 BUG_ON(!service_tree);
2276 BUG_ON(!service_tree->count);
2278 if (!cfqd->cfq_slice_idle)
2281 /* We never do for idle class queues. */
2282 if (prio == IDLE_WORKLOAD)
2285 /* We do for queues that were marked with idle window flag. */
2286 if (cfq_cfqq_idle_window(cfqq) &&
2287 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2291 * Otherwise, we do only if they are the last ones
2292 * in their service tree.
2294 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2295 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
2297 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2298 service_tree->count);
2302 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2304 struct cfq_queue *cfqq = cfqd->active_queue;
2305 struct cfq_io_cq *cic;
2306 unsigned long sl, group_idle = 0;
2309 * SSD device without seek penalty, disable idling. But only do so
2310 * for devices that support queuing, otherwise we still have a problem
2311 * with sync vs async workloads.
2313 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2316 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2317 WARN_ON(cfq_cfqq_slice_new(cfqq));
2320 * idle is disabled, either manually or by past process history
2322 if (!cfq_should_idle(cfqd, cfqq)) {
2323 /* no queue idling. Check for group idling */
2324 if (cfqd->cfq_group_idle)
2325 group_idle = cfqd->cfq_group_idle;
2331 * still active requests from this queue, don't idle
2333 if (cfqq->dispatched)
2337 * task has exited, don't wait
2339 cic = cfqd->active_cic;
2340 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2344 * If our average think time is larger than the remaining time
2345 * slice, then don't idle. This avoids overrunning the allotted
2348 if (sample_valid(cic->ttime.ttime_samples) &&
2349 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2350 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2351 cic->ttime.ttime_mean);
2355 /* There are other queues in the group, don't do group idle */
2356 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2359 cfq_mark_cfqq_wait_request(cfqq);
2362 sl = cfqd->cfq_group_idle;
2364 sl = cfqd->cfq_slice_idle;
2366 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2367 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2368 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2369 group_idle ? 1 : 0);
2373 * Move request from internal lists to the request queue dispatch list.
2375 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2377 struct cfq_data *cfqd = q->elevator->elevator_data;
2378 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2380 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2382 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2383 cfq_remove_request(rq);
2385 (RQ_CFQG(rq))->dispatched++;
2386 elv_dispatch_sort(q, rq);
2388 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2389 cfqq->nr_sectors += blk_rq_sectors(rq);
2390 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2394 * return expired entry, or NULL to just start from scratch in rbtree
2396 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2398 struct request *rq = NULL;
2400 if (cfq_cfqq_fifo_expire(cfqq))
2403 cfq_mark_cfqq_fifo_expire(cfqq);
2405 if (list_empty(&cfqq->fifo))
2408 rq = rq_entry_fifo(cfqq->fifo.next);
2409 if (time_before(jiffies, rq_fifo_time(rq)))
2412 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2417 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2419 const int base_rq = cfqd->cfq_slice_async_rq;
2421 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2423 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2427 * Must be called with the queue_lock held.
2429 static int cfqq_process_refs(struct cfq_queue *cfqq)
2431 int process_refs, io_refs;
2433 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2434 process_refs = cfqq->ref - io_refs;
2435 BUG_ON(process_refs < 0);
2436 return process_refs;
2439 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2441 int process_refs, new_process_refs;
2442 struct cfq_queue *__cfqq;
2445 * If there are no process references on the new_cfqq, then it is
2446 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2447 * chain may have dropped their last reference (not just their
2448 * last process reference).
2450 if (!cfqq_process_refs(new_cfqq))
2453 /* Avoid a circular list and skip interim queue merges */
2454 while ((__cfqq = new_cfqq->new_cfqq)) {
2460 process_refs = cfqq_process_refs(cfqq);
2461 new_process_refs = cfqq_process_refs(new_cfqq);
2463 * If the process for the cfqq has gone away, there is no
2464 * sense in merging the queues.
2466 if (process_refs == 0 || new_process_refs == 0)
2470 * Merge in the direction of the lesser amount of work.
2472 if (new_process_refs >= process_refs) {
2473 cfqq->new_cfqq = new_cfqq;
2474 new_cfqq->ref += process_refs;
2476 new_cfqq->new_cfqq = cfqq;
2477 cfqq->ref += new_process_refs;
2481 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2482 struct cfq_group *cfqg, enum wl_prio_t prio)
2484 struct cfq_queue *queue;
2486 bool key_valid = false;
2487 unsigned long lowest_key = 0;
2488 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2490 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2491 /* select the one with lowest rb_key */
2492 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2494 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2495 lowest_key = queue->rb_key;
2504 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2508 struct cfq_rb_root *st;
2509 unsigned group_slice;
2510 enum wl_prio_t original_prio = cfqd->serving_prio;
2512 /* Choose next priority. RT > BE > IDLE */
2513 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2514 cfqd->serving_prio = RT_WORKLOAD;
2515 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2516 cfqd->serving_prio = BE_WORKLOAD;
2518 cfqd->serving_prio = IDLE_WORKLOAD;
2519 cfqd->workload_expires = jiffies + 1;
2523 if (original_prio != cfqd->serving_prio)
2527 * For RT and BE, we have to choose also the type
2528 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2531 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2535 * check workload expiration, and that we still have other queues ready
2537 if (count && !time_after(jiffies, cfqd->workload_expires))
2541 /* otherwise select new workload type */
2542 cfqd->serving_type =
2543 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2544 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2548 * the workload slice is computed as a fraction of target latency
2549 * proportional to the number of queues in that workload, over
2550 * all the queues in the same priority class
2552 group_slice = cfq_group_slice(cfqd, cfqg);
2554 slice = group_slice * count /
2555 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2556 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2558 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2562 * Async queues are currently system wide. Just taking
2563 * proportion of queues with-in same group will lead to higher
2564 * async ratio system wide as generally root group is going
2565 * to have higher weight. A more accurate thing would be to
2566 * calculate system wide asnc/sync ratio.
2568 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2569 tmp = tmp/cfqd->busy_queues;
2570 slice = min_t(unsigned, slice, tmp);
2572 /* async workload slice is scaled down according to
2573 * the sync/async slice ratio. */
2574 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2576 /* sync workload slice is at least 2 * cfq_slice_idle */
2577 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2579 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2580 cfq_log(cfqd, "workload slice:%d", slice);
2581 cfqd->workload_expires = jiffies + slice;
2584 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2586 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2587 struct cfq_group *cfqg;
2589 if (RB_EMPTY_ROOT(&st->rb))
2591 cfqg = cfq_rb_first_group(st);
2592 update_min_vdisktime(st);
2596 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2598 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2600 cfqd->serving_group = cfqg;
2602 /* Restore the workload type data */
2603 if (cfqg->saved_workload_slice) {
2604 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2605 cfqd->serving_type = cfqg->saved_workload;
2606 cfqd->serving_prio = cfqg->saved_serving_prio;
2608 cfqd->workload_expires = jiffies - 1;
2610 choose_service_tree(cfqd, cfqg);
2614 * Select a queue for service. If we have a current active queue,
2615 * check whether to continue servicing it, or retrieve and set a new one.
2617 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2619 struct cfq_queue *cfqq, *new_cfqq = NULL;
2621 cfqq = cfqd->active_queue;
2625 if (!cfqd->rq_queued)
2629 * We were waiting for group to get backlogged. Expire the queue
2631 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2635 * The active queue has run out of time, expire it and select new.
2637 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2639 * If slice had not expired at the completion of last request
2640 * we might not have turned on wait_busy flag. Don't expire
2641 * the queue yet. Allow the group to get backlogged.
2643 * The very fact that we have used the slice, that means we
2644 * have been idling all along on this queue and it should be
2645 * ok to wait for this request to complete.
2647 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2648 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2652 goto check_group_idle;
2656 * The active queue has requests and isn't expired, allow it to
2659 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2663 * If another queue has a request waiting within our mean seek
2664 * distance, let it run. The expire code will check for close
2665 * cooperators and put the close queue at the front of the service
2666 * tree. If possible, merge the expiring queue with the new cfqq.
2668 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2670 if (!cfqq->new_cfqq)
2671 cfq_setup_merge(cfqq, new_cfqq);
2676 * No requests pending. If the active queue still has requests in
2677 * flight or is idling for a new request, allow either of these
2678 * conditions to happen (or time out) before selecting a new queue.
2680 if (timer_pending(&cfqd->idle_slice_timer)) {
2686 * This is a deep seek queue, but the device is much faster than
2687 * the queue can deliver, don't idle
2689 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2690 (cfq_cfqq_slice_new(cfqq) ||
2691 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2692 cfq_clear_cfqq_deep(cfqq);
2693 cfq_clear_cfqq_idle_window(cfqq);
2696 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2702 * If group idle is enabled and there are requests dispatched from
2703 * this group, wait for requests to complete.
2706 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2707 cfqq->cfqg->dispatched &&
2708 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2714 cfq_slice_expired(cfqd, 0);
2717 * Current queue expired. Check if we have to switch to a new
2721 cfq_choose_cfqg(cfqd);
2723 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2728 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2732 while (cfqq->next_rq) {
2733 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2737 BUG_ON(!list_empty(&cfqq->fifo));
2739 /* By default cfqq is not expired if it is empty. Do it explicitly */
2740 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2745 * Drain our current requests. Used for barriers and when switching
2746 * io schedulers on-the-fly.
2748 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2750 struct cfq_queue *cfqq;
2753 /* Expire the timeslice of the current active queue first */
2754 cfq_slice_expired(cfqd, 0);
2755 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2756 __cfq_set_active_queue(cfqd, cfqq);
2757 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2760 BUG_ON(cfqd->busy_queues);
2762 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2766 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2767 struct cfq_queue *cfqq)
2769 /* the queue hasn't finished any request, can't estimate */
2770 if (cfq_cfqq_slice_new(cfqq))
2772 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2779 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2781 unsigned int max_dispatch;
2784 * Drain async requests before we start sync IO
2786 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2790 * If this is an async queue and we have sync IO in flight, let it wait
2792 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2795 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2796 if (cfq_class_idle(cfqq))
2800 * Does this cfqq already have too much IO in flight?
2802 if (cfqq->dispatched >= max_dispatch) {
2803 bool promote_sync = false;
2805 * idle queue must always only have a single IO in flight
2807 if (cfq_class_idle(cfqq))
2811 * If there is only one sync queue
2812 * we can ignore async queue here and give the sync
2813 * queue no dispatch limit. The reason is a sync queue can
2814 * preempt async queue, limiting the sync queue doesn't make
2815 * sense. This is useful for aiostress test.
2817 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2818 promote_sync = true;
2821 * We have other queues, don't allow more IO from this one
2823 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2828 * Sole queue user, no limit
2830 if (cfqd->busy_queues == 1 || promote_sync)
2834 * Normally we start throttling cfqq when cfq_quantum/2
2835 * requests have been dispatched. But we can drive
2836 * deeper queue depths at the beginning of slice
2837 * subjected to upper limit of cfq_quantum.
2839 max_dispatch = cfqd->cfq_quantum;
2843 * Async queues must wait a bit before being allowed dispatch.
2844 * We also ramp up the dispatch depth gradually for async IO,
2845 * based on the last sync IO we serviced
2847 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2848 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2851 depth = last_sync / cfqd->cfq_slice[1];
2852 if (!depth && !cfqq->dispatched)
2854 if (depth < max_dispatch)
2855 max_dispatch = depth;
2859 * If we're below the current max, allow a dispatch
2861 return cfqq->dispatched < max_dispatch;
2865 * Dispatch a request from cfqq, moving them to the request queue
2868 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2872 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2874 if (!cfq_may_dispatch(cfqd, cfqq))
2878 * follow expired path, else get first next available
2880 rq = cfq_check_fifo(cfqq);
2885 * insert request into driver dispatch list
2887 cfq_dispatch_insert(cfqd->queue, rq);
2889 if (!cfqd->active_cic) {
2890 struct cfq_io_cq *cic = RQ_CIC(rq);
2892 atomic_long_inc(&cic->icq.ioc->refcount);
2893 cfqd->active_cic = cic;
2900 * Find the cfqq that we need to service and move a request from that to the
2903 static int cfq_dispatch_requests(struct request_queue *q, int force)
2905 struct cfq_data *cfqd = q->elevator->elevator_data;
2906 struct cfq_queue *cfqq;
2908 if (!cfqd->busy_queues)
2911 if (unlikely(force))
2912 return cfq_forced_dispatch(cfqd);
2914 cfqq = cfq_select_queue(cfqd);
2919 * Dispatch a request from this cfqq, if it is allowed
2921 if (!cfq_dispatch_request(cfqd, cfqq))
2924 cfqq->slice_dispatch++;
2925 cfq_clear_cfqq_must_dispatch(cfqq);
2928 * expire an async queue immediately if it has used up its slice. idle
2929 * queue always expire after 1 dispatch round.
2931 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2932 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2933 cfq_class_idle(cfqq))) {
2934 cfqq->slice_end = jiffies + 1;
2935 cfq_slice_expired(cfqd, 0);
2938 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2943 * task holds one reference to the queue, dropped when task exits. each rq
2944 * in-flight on this queue also holds a reference, dropped when rq is freed.
2946 * Each cfq queue took a reference on the parent group. Drop it now.
2947 * queue lock must be held here.
2949 static void cfq_put_queue(struct cfq_queue *cfqq)
2951 struct cfq_data *cfqd = cfqq->cfqd;
2952 struct cfq_group *cfqg;
2954 BUG_ON(cfqq->ref <= 0);
2960 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2961 BUG_ON(rb_first(&cfqq->sort_list));
2962 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2965 if (unlikely(cfqd->active_queue == cfqq)) {
2966 __cfq_slice_expired(cfqd, cfqq, 0);
2967 cfq_schedule_dispatch(cfqd);
2970 BUG_ON(cfq_cfqq_on_rr(cfqq));
2971 kmem_cache_free(cfq_pool, cfqq);
2975 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2977 struct cfq_queue *__cfqq, *next;
2980 * If this queue was scheduled to merge with another queue, be
2981 * sure to drop the reference taken on that queue (and others in
2982 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2984 __cfqq = cfqq->new_cfqq;
2986 if (__cfqq == cfqq) {
2987 WARN(1, "cfqq->new_cfqq loop detected\n");
2990 next = __cfqq->new_cfqq;
2991 cfq_put_queue(__cfqq);
2996 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2998 if (unlikely(cfqq == cfqd->active_queue)) {
2999 __cfq_slice_expired(cfqd, cfqq, 0);
3000 cfq_schedule_dispatch(cfqd);
3003 cfq_put_cooperator(cfqq);
3005 cfq_put_queue(cfqq);
3008 static void cfq_init_icq(struct io_cq *icq)
3010 struct cfq_io_cq *cic = icq_to_cic(icq);
3012 cic->ttime.last_end_request = jiffies;
3015 static void cfq_exit_icq(struct io_cq *icq)
3017 struct cfq_io_cq *cic = icq_to_cic(icq);
3018 struct cfq_data *cfqd = cic_to_cfqd(cic);
3020 if (cic->cfqq[BLK_RW_ASYNC]) {
3021 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3022 cic->cfqq[BLK_RW_ASYNC] = NULL;
3025 if (cic->cfqq[BLK_RW_SYNC]) {
3026 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3027 cic->cfqq[BLK_RW_SYNC] = NULL;
3031 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3033 struct task_struct *tsk = current;
3036 if (!cfq_cfqq_prio_changed(cfqq))
3039 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3040 switch (ioprio_class) {
3042 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3043 case IOPRIO_CLASS_NONE:
3045 * no prio set, inherit CPU scheduling settings
3047 cfqq->ioprio = task_nice_ioprio(tsk);
3048 cfqq->ioprio_class = task_nice_ioclass(tsk);
3050 case IOPRIO_CLASS_RT:
3051 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3052 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3054 case IOPRIO_CLASS_BE:
3055 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3056 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3058 case IOPRIO_CLASS_IDLE:
3059 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3061 cfq_clear_cfqq_idle_window(cfqq);
3066 * keep track of original prio settings in case we have to temporarily
3067 * elevate the priority of this queue
3069 cfqq->org_ioprio = cfqq->ioprio;
3070 cfq_clear_cfqq_prio_changed(cfqq);
3073 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3075 int ioprio = cic->icq.ioc->ioprio;
3076 struct cfq_data *cfqd = cic_to_cfqd(cic);
3077 struct cfq_queue *cfqq;
3080 * Check whether ioprio has changed. The condition may trigger
3081 * spuriously on a newly created cic but there's no harm.
3083 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3086 cfqq = cic->cfqq[BLK_RW_ASYNC];
3088 struct cfq_queue *new_cfqq;
3089 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3092 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3093 cfq_put_queue(cfqq);
3097 cfqq = cic->cfqq[BLK_RW_SYNC];
3099 cfq_mark_cfqq_prio_changed(cfqq);
3101 cic->ioprio = ioprio;
3104 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3105 pid_t pid, bool is_sync)
3107 RB_CLEAR_NODE(&cfqq->rb_node);
3108 RB_CLEAR_NODE(&cfqq->p_node);
3109 INIT_LIST_HEAD(&cfqq->fifo);
3114 cfq_mark_cfqq_prio_changed(cfqq);
3117 if (!cfq_class_idle(cfqq))
3118 cfq_mark_cfqq_idle_window(cfqq);
3119 cfq_mark_cfqq_sync(cfqq);
3124 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3125 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3127 struct cfq_data *cfqd = cic_to_cfqd(cic);
3128 struct cfq_queue *sync_cfqq;
3132 id = bio_blkio_cgroup(bio)->id;
3136 * Check whether blkcg has changed. The condition may trigger
3137 * spuriously on a newly created cic but there's no harm.
3139 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3142 sync_cfqq = cic_to_cfqq(cic, 1);
3145 * Drop reference to sync queue. A new sync queue will be
3146 * assigned in new group upon arrival of a fresh request.
3148 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3149 cic_set_cfqq(cic, NULL, 1);
3150 cfq_put_queue(sync_cfqq);
3156 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3157 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3159 static struct cfq_queue *
3160 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3161 struct bio *bio, gfp_t gfp_mask)
3163 struct blkio_cgroup *blkcg;
3164 struct cfq_queue *cfqq, *new_cfqq = NULL;
3165 struct cfq_group *cfqg;
3170 blkcg = bio_blkio_cgroup(bio);
3171 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3172 cfqq = cic_to_cfqq(cic, is_sync);
3175 * Always try a new alloc if we fell back to the OOM cfqq
3176 * originally, since it should just be a temporary situation.
3178 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3183 } else if (gfp_mask & __GFP_WAIT) {
3185 spin_unlock_irq(cfqd->queue->queue_lock);
3186 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3187 gfp_mask | __GFP_ZERO,
3189 spin_lock_irq(cfqd->queue->queue_lock);
3193 cfqq = kmem_cache_alloc_node(cfq_pool,
3194 gfp_mask | __GFP_ZERO,
3199 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3200 cfq_init_prio_data(cfqq, cic);
3201 cfq_link_cfqq_cfqg(cfqq, cfqg);
3202 cfq_log_cfqq(cfqd, cfqq, "alloced");
3204 cfqq = &cfqd->oom_cfqq;
3208 kmem_cache_free(cfq_pool, new_cfqq);
3214 static struct cfq_queue **
3215 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3217 switch (ioprio_class) {
3218 case IOPRIO_CLASS_RT:
3219 return &cfqd->async_cfqq[0][ioprio];
3220 case IOPRIO_CLASS_NONE:
3221 ioprio = IOPRIO_NORM;
3223 case IOPRIO_CLASS_BE:
3224 return &cfqd->async_cfqq[1][ioprio];
3225 case IOPRIO_CLASS_IDLE:
3226 return &cfqd->async_idle_cfqq;
3232 static struct cfq_queue *
3233 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3234 struct bio *bio, gfp_t gfp_mask)
3236 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3237 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3238 struct cfq_queue **async_cfqq = NULL;
3239 struct cfq_queue *cfqq = NULL;
3242 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3247 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3250 * pin the queue now that it's allocated, scheduler exit will prune it
3252 if (!is_sync && !(*async_cfqq)) {
3262 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3264 unsigned long elapsed = jiffies - ttime->last_end_request;
3265 elapsed = min(elapsed, 2UL * slice_idle);
3267 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3268 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3269 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3273 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3274 struct cfq_io_cq *cic)
3276 if (cfq_cfqq_sync(cfqq)) {
3277 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3278 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3279 cfqd->cfq_slice_idle);
3281 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3282 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3287 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3291 sector_t n_sec = blk_rq_sectors(rq);
3292 if (cfqq->last_request_pos) {
3293 if (cfqq->last_request_pos < blk_rq_pos(rq))
3294 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3296 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3299 cfqq->seek_history <<= 1;
3300 if (blk_queue_nonrot(cfqd->queue))
3301 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3303 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3307 * Disable idle window if the process thinks too long or seeks so much that
3311 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3312 struct cfq_io_cq *cic)
3314 int old_idle, enable_idle;
3317 * Don't idle for async or idle io prio class
3319 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3322 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3324 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3325 cfq_mark_cfqq_deep(cfqq);
3327 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3329 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3330 !cfqd->cfq_slice_idle ||
3331 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3333 else if (sample_valid(cic->ttime.ttime_samples)) {
3334 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3340 if (old_idle != enable_idle) {
3341 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3343 cfq_mark_cfqq_idle_window(cfqq);
3345 cfq_clear_cfqq_idle_window(cfqq);
3350 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3351 * no or if we aren't sure, a 1 will cause a preempt.
3354 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3357 struct cfq_queue *cfqq;
3359 cfqq = cfqd->active_queue;
3363 if (cfq_class_idle(new_cfqq))
3366 if (cfq_class_idle(cfqq))
3370 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3372 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3376 * if the new request is sync, but the currently running queue is
3377 * not, let the sync request have priority.
3379 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3382 if (new_cfqq->cfqg != cfqq->cfqg)
3385 if (cfq_slice_used(cfqq))
3388 /* Allow preemption only if we are idling on sync-noidle tree */
3389 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3390 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3391 new_cfqq->service_tree->count == 2 &&
3392 RB_EMPTY_ROOT(&cfqq->sort_list))
3396 * So both queues are sync. Let the new request get disk time if
3397 * it's a metadata request and the current queue is doing regular IO.
3399 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3403 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3405 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3408 /* An idle queue should not be idle now for some reason */
3409 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3412 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3416 * if this request is as-good as one we would expect from the
3417 * current cfqq, let it preempt
3419 if (cfq_rq_close(cfqd, cfqq, rq))
3426 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3427 * let it have half of its nominal slice.
3429 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3431 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3433 cfq_log_cfqq(cfqd, cfqq, "preempt");
3434 cfq_slice_expired(cfqd, 1);
3437 * workload type is changed, don't save slice, otherwise preempt
3440 if (old_type != cfqq_type(cfqq))
3441 cfqq->cfqg->saved_workload_slice = 0;
3444 * Put the new queue at the front of the of the current list,
3445 * so we know that it will be selected next.
3447 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3449 cfq_service_tree_add(cfqd, cfqq, 1);
3451 cfqq->slice_end = 0;
3452 cfq_mark_cfqq_slice_new(cfqq);
3456 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3457 * something we should do about it
3460 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3463 struct cfq_io_cq *cic = RQ_CIC(rq);
3466 if (rq->cmd_flags & REQ_PRIO)
3467 cfqq->prio_pending++;
3469 cfq_update_io_thinktime(cfqd, cfqq, cic);
3470 cfq_update_io_seektime(cfqd, cfqq, rq);
3471 cfq_update_idle_window(cfqd, cfqq, cic);
3473 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3475 if (cfqq == cfqd->active_queue) {
3477 * Remember that we saw a request from this process, but
3478 * don't start queuing just yet. Otherwise we risk seeing lots
3479 * of tiny requests, because we disrupt the normal plugging
3480 * and merging. If the request is already larger than a single
3481 * page, let it rip immediately. For that case we assume that
3482 * merging is already done. Ditto for a busy system that
3483 * has other work pending, don't risk delaying until the
3484 * idle timer unplug to continue working.
3486 if (cfq_cfqq_wait_request(cfqq)) {
3487 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3488 cfqd->busy_queues > 1) {
3489 cfq_del_timer(cfqd, cfqq);
3490 cfq_clear_cfqq_wait_request(cfqq);
3491 __blk_run_queue(cfqd->queue);
3493 cfqg_stats_update_idle_time(cfqq->cfqg);
3494 cfq_mark_cfqq_must_dispatch(cfqq);
3497 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3499 * not the active queue - expire current slice if it is
3500 * idle and has expired it's mean thinktime or this new queue
3501 * has some old slice time left and is of higher priority or
3502 * this new queue is RT and the current one is BE
3504 cfq_preempt_queue(cfqd, cfqq);
3505 __blk_run_queue(cfqd->queue);
3509 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3511 struct cfq_data *cfqd = q->elevator->elevator_data;
3512 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3514 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3515 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3517 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3518 list_add_tail(&rq->queuelist, &cfqq->fifo);
3520 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3522 cfq_rq_enqueued(cfqd, cfqq, rq);
3526 * Update hw_tag based on peak queue depth over 50 samples under
3529 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3531 struct cfq_queue *cfqq = cfqd->active_queue;
3533 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3534 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3536 if (cfqd->hw_tag == 1)
3539 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3540 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3544 * If active queue hasn't enough requests and can idle, cfq might not
3545 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3548 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3549 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3550 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3553 if (cfqd->hw_tag_samples++ < 50)
3556 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3562 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3564 struct cfq_io_cq *cic = cfqd->active_cic;
3566 /* If the queue already has requests, don't wait */
3567 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3570 /* If there are other queues in the group, don't wait */
3571 if (cfqq->cfqg->nr_cfqq > 1)
3574 /* the only queue in the group, but think time is big */
3575 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3578 if (cfq_slice_used(cfqq))
3581 /* if slice left is less than think time, wait busy */
3582 if (cic && sample_valid(cic->ttime.ttime_samples)
3583 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3587 * If think times is less than a jiffy than ttime_mean=0 and above
3588 * will not be true. It might happen that slice has not expired yet
3589 * but will expire soon (4-5 ns) during select_queue(). To cover the
3590 * case where think time is less than a jiffy, mark the queue wait
3591 * busy if only 1 jiffy is left in the slice.
3593 if (cfqq->slice_end - jiffies == 1)
3599 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3601 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3602 struct cfq_data *cfqd = cfqq->cfqd;
3603 const int sync = rq_is_sync(rq);
3607 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3608 !!(rq->cmd_flags & REQ_NOIDLE));
3610 cfq_update_hw_tag(cfqd);
3612 WARN_ON(!cfqd->rq_in_driver);
3613 WARN_ON(!cfqq->dispatched);
3614 cfqd->rq_in_driver--;
3616 (RQ_CFQG(rq))->dispatched--;
3617 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3618 rq_io_start_time_ns(rq), rq->cmd_flags);
3620 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3623 struct cfq_rb_root *service_tree;
3625 RQ_CIC(rq)->ttime.last_end_request = now;
3627 if (cfq_cfqq_on_rr(cfqq))
3628 service_tree = cfqq->service_tree;
3630 service_tree = service_tree_for(cfqq->cfqg,
3631 cfqq_prio(cfqq), cfqq_type(cfqq));
3632 service_tree->ttime.last_end_request = now;
3633 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3634 cfqd->last_delayed_sync = now;
3637 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3638 cfqq->cfqg->ttime.last_end_request = now;
3642 * If this is the active queue, check if it needs to be expired,
3643 * or if we want to idle in case it has no pending requests.
3645 if (cfqd->active_queue == cfqq) {
3646 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3648 if (cfq_cfqq_slice_new(cfqq)) {
3649 cfq_set_prio_slice(cfqd, cfqq);
3650 cfq_clear_cfqq_slice_new(cfqq);
3654 * Should we wait for next request to come in before we expire
3657 if (cfq_should_wait_busy(cfqd, cfqq)) {
3658 unsigned long extend_sl = cfqd->cfq_slice_idle;
3659 if (!cfqd->cfq_slice_idle)
3660 extend_sl = cfqd->cfq_group_idle;
3661 cfqq->slice_end = jiffies + extend_sl;
3662 cfq_mark_cfqq_wait_busy(cfqq);
3663 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3667 * Idling is not enabled on:
3669 * - idle-priority queues
3671 * - queues with still some requests queued
3672 * - when there is a close cooperator
3674 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3675 cfq_slice_expired(cfqd, 1);
3676 else if (sync && cfqq_empty &&
3677 !cfq_close_cooperator(cfqd, cfqq)) {
3678 cfq_arm_slice_timer(cfqd);
3682 if (!cfqd->rq_in_driver)
3683 cfq_schedule_dispatch(cfqd);
3686 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3688 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3689 cfq_mark_cfqq_must_alloc_slice(cfqq);
3690 return ELV_MQUEUE_MUST;
3693 return ELV_MQUEUE_MAY;
3696 static int cfq_may_queue(struct request_queue *q, int rw)
3698 struct cfq_data *cfqd = q->elevator->elevator_data;
3699 struct task_struct *tsk = current;
3700 struct cfq_io_cq *cic;
3701 struct cfq_queue *cfqq;
3704 * don't force setup of a queue from here, as a call to may_queue
3705 * does not necessarily imply that a request actually will be queued.
3706 * so just lookup a possibly existing queue, or return 'may queue'
3709 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3711 return ELV_MQUEUE_MAY;
3713 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3715 cfq_init_prio_data(cfqq, cic);
3717 return __cfq_may_queue(cfqq);
3720 return ELV_MQUEUE_MAY;
3724 * queue lock held here
3726 static void cfq_put_request(struct request *rq)
3728 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3731 const int rw = rq_data_dir(rq);
3733 BUG_ON(!cfqq->allocated[rw]);
3734 cfqq->allocated[rw]--;
3736 /* Put down rq reference on cfqg */
3737 cfqg_put(RQ_CFQG(rq));
3738 rq->elv.priv[0] = NULL;
3739 rq->elv.priv[1] = NULL;
3741 cfq_put_queue(cfqq);
3745 static struct cfq_queue *
3746 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3747 struct cfq_queue *cfqq)
3749 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3750 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3751 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3752 cfq_put_queue(cfqq);
3753 return cic_to_cfqq(cic, 1);
3757 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3758 * was the last process referring to said cfqq.
3760 static struct cfq_queue *
3761 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3763 if (cfqq_process_refs(cfqq) == 1) {
3764 cfqq->pid = current->pid;
3765 cfq_clear_cfqq_coop(cfqq);
3766 cfq_clear_cfqq_split_coop(cfqq);
3770 cic_set_cfqq(cic, NULL, 1);
3772 cfq_put_cooperator(cfqq);
3774 cfq_put_queue(cfqq);
3778 * Allocate cfq data structures associated with this request.
3781 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3784 struct cfq_data *cfqd = q->elevator->elevator_data;
3785 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3786 const int rw = rq_data_dir(rq);
3787 const bool is_sync = rq_is_sync(rq);
3788 struct cfq_queue *cfqq;
3790 might_sleep_if(gfp_mask & __GFP_WAIT);
3792 spin_lock_irq(q->queue_lock);
3794 check_ioprio_changed(cic, bio);
3795 check_blkcg_changed(cic, bio);
3797 cfqq = cic_to_cfqq(cic, is_sync);
3798 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3799 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3800 cic_set_cfqq(cic, cfqq, is_sync);
3803 * If the queue was seeky for too long, break it apart.
3805 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3806 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3807 cfqq = split_cfqq(cic, cfqq);
3813 * Check to see if this queue is scheduled to merge with
3814 * another, closely cooperating queue. The merging of
3815 * queues happens here as it must be done in process context.
3816 * The reference on new_cfqq was taken in merge_cfqqs.
3819 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3822 cfqq->allocated[rw]++;
3825 cfqg_get(cfqq->cfqg);
3826 rq->elv.priv[0] = cfqq;
3827 rq->elv.priv[1] = cfqq->cfqg;
3828 spin_unlock_irq(q->queue_lock);
3832 static void cfq_kick_queue(struct work_struct *work)
3834 struct cfq_data *cfqd =
3835 container_of(work, struct cfq_data, unplug_work);
3836 struct request_queue *q = cfqd->queue;
3838 spin_lock_irq(q->queue_lock);
3839 __blk_run_queue(cfqd->queue);
3840 spin_unlock_irq(q->queue_lock);
3844 * Timer running if the active_queue is currently idling inside its time slice
3846 static void cfq_idle_slice_timer(unsigned long data)
3848 struct cfq_data *cfqd = (struct cfq_data *) data;
3849 struct cfq_queue *cfqq;
3850 unsigned long flags;
3853 cfq_log(cfqd, "idle timer fired");
3855 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3857 cfqq = cfqd->active_queue;
3862 * We saw a request before the queue expired, let it through
3864 if (cfq_cfqq_must_dispatch(cfqq))
3870 if (cfq_slice_used(cfqq))
3874 * only expire and reinvoke request handler, if there are
3875 * other queues with pending requests
3877 if (!cfqd->busy_queues)
3881 * not expired and it has a request pending, let it dispatch
3883 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3887 * Queue depth flag is reset only when the idle didn't succeed
3889 cfq_clear_cfqq_deep(cfqq);
3892 cfq_slice_expired(cfqd, timed_out);
3894 cfq_schedule_dispatch(cfqd);
3896 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3899 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3901 del_timer_sync(&cfqd->idle_slice_timer);
3902 cancel_work_sync(&cfqd->unplug_work);
3905 static void cfq_put_async_queues(struct cfq_data *cfqd)
3909 for (i = 0; i < IOPRIO_BE_NR; i++) {
3910 if (cfqd->async_cfqq[0][i])
3911 cfq_put_queue(cfqd->async_cfqq[0][i]);
3912 if (cfqd->async_cfqq[1][i])
3913 cfq_put_queue(cfqd->async_cfqq[1][i]);
3916 if (cfqd->async_idle_cfqq)
3917 cfq_put_queue(cfqd->async_idle_cfqq);
3920 static void cfq_exit_queue(struct elevator_queue *e)
3922 struct cfq_data *cfqd = e->elevator_data;
3923 struct request_queue *q = cfqd->queue;
3925 cfq_shutdown_timer_wq(cfqd);
3927 spin_lock_irq(q->queue_lock);
3929 if (cfqd->active_queue)
3930 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3932 cfq_put_async_queues(cfqd);
3934 spin_unlock_irq(q->queue_lock);
3936 cfq_shutdown_timer_wq(cfqd);
3938 #ifndef CONFIG_CFQ_GROUP_IOSCHED
3939 kfree(cfqd->root_group);
3941 update_root_blkg_pd(q, &blkio_policy_cfq);
3945 static int cfq_init_queue(struct request_queue *q)
3947 struct cfq_data *cfqd;
3948 struct blkio_group *blkg __maybe_unused;
3951 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3956 q->elevator->elevator_data = cfqd;
3958 /* Init root service tree */
3959 cfqd->grp_service_tree = CFQ_RB_ROOT;
3961 /* Init root group and prefer root group over other groups by default */
3962 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3964 spin_lock_irq(q->queue_lock);
3966 blkg = blkg_lookup_create(&blkio_root_cgroup, q, true);
3968 cfqd->root_group = blkg_to_cfqg(blkg);
3970 spin_unlock_irq(q->queue_lock);
3973 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3974 GFP_KERNEL, cfqd->queue->node);
3975 if (cfqd->root_group)
3976 cfq_init_cfqg_base(cfqd->root_group);
3978 if (!cfqd->root_group) {
3983 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3986 * Not strictly needed (since RB_ROOT just clears the node and we
3987 * zeroed cfqd on alloc), but better be safe in case someone decides
3988 * to add magic to the rb code
3990 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3991 cfqd->prio_trees[i] = RB_ROOT;
3994 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3995 * Grab a permanent reference to it, so that the normal code flow
3996 * will not attempt to free it. oom_cfqq is linked to root_group
3997 * but shouldn't hold a reference as it'll never be unlinked. Lose
3998 * the reference from linking right away.
4000 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4001 cfqd->oom_cfqq.ref++;
4003 spin_lock_irq(q->queue_lock);
4004 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4005 cfqg_put(cfqd->root_group);
4006 spin_unlock_irq(q->queue_lock);
4008 init_timer(&cfqd->idle_slice_timer);
4009 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4010 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4012 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4014 cfqd->cfq_quantum = cfq_quantum;
4015 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4016 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4017 cfqd->cfq_back_max = cfq_back_max;
4018 cfqd->cfq_back_penalty = cfq_back_penalty;
4019 cfqd->cfq_slice[0] = cfq_slice_async;
4020 cfqd->cfq_slice[1] = cfq_slice_sync;
4021 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4022 cfqd->cfq_slice_idle = cfq_slice_idle;
4023 cfqd->cfq_group_idle = cfq_group_idle;
4024 cfqd->cfq_latency = 1;
4027 * we optimistically start assuming sync ops weren't delayed in last
4028 * second, in order to have larger depth for async operations.
4030 cfqd->last_delayed_sync = jiffies - HZ;
4035 * sysfs parts below -->
4038 cfq_var_show(unsigned int var, char *page)
4040 return sprintf(page, "%d\n", var);
4044 cfq_var_store(unsigned int *var, const char *page, size_t count)
4046 char *p = (char *) page;
4048 *var = simple_strtoul(p, &p, 10);
4052 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4053 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4055 struct cfq_data *cfqd = e->elevator_data; \
4056 unsigned int __data = __VAR; \
4058 __data = jiffies_to_msecs(__data); \
4059 return cfq_var_show(__data, (page)); \
4061 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4062 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4063 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4064 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4065 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4066 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4067 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4068 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4069 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4070 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4071 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4072 #undef SHOW_FUNCTION
4074 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4075 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4077 struct cfq_data *cfqd = e->elevator_data; \
4078 unsigned int __data; \
4079 int ret = cfq_var_store(&__data, (page), count); \
4080 if (__data < (MIN)) \
4082 else if (__data > (MAX)) \
4085 *(__PTR) = msecs_to_jiffies(__data); \
4087 *(__PTR) = __data; \
4090 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4091 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4093 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4095 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4096 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4098 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4099 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4100 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4101 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4102 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4104 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4105 #undef STORE_FUNCTION
4107 #define CFQ_ATTR(name) \
4108 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4110 static struct elv_fs_entry cfq_attrs[] = {
4112 CFQ_ATTR(fifo_expire_sync),
4113 CFQ_ATTR(fifo_expire_async),
4114 CFQ_ATTR(back_seek_max),
4115 CFQ_ATTR(back_seek_penalty),
4116 CFQ_ATTR(slice_sync),
4117 CFQ_ATTR(slice_async),
4118 CFQ_ATTR(slice_async_rq),
4119 CFQ_ATTR(slice_idle),
4120 CFQ_ATTR(group_idle),
4121 CFQ_ATTR(low_latency),
4125 static struct elevator_type iosched_cfq = {
4127 .elevator_merge_fn = cfq_merge,
4128 .elevator_merged_fn = cfq_merged_request,
4129 .elevator_merge_req_fn = cfq_merged_requests,
4130 .elevator_allow_merge_fn = cfq_allow_merge,
4131 .elevator_bio_merged_fn = cfq_bio_merged,
4132 .elevator_dispatch_fn = cfq_dispatch_requests,
4133 .elevator_add_req_fn = cfq_insert_request,
4134 .elevator_activate_req_fn = cfq_activate_request,
4135 .elevator_deactivate_req_fn = cfq_deactivate_request,
4136 .elevator_completed_req_fn = cfq_completed_request,
4137 .elevator_former_req_fn = elv_rb_former_request,
4138 .elevator_latter_req_fn = elv_rb_latter_request,
4139 .elevator_init_icq_fn = cfq_init_icq,
4140 .elevator_exit_icq_fn = cfq_exit_icq,
4141 .elevator_set_req_fn = cfq_set_request,
4142 .elevator_put_req_fn = cfq_put_request,
4143 .elevator_may_queue_fn = cfq_may_queue,
4144 .elevator_init_fn = cfq_init_queue,
4145 .elevator_exit_fn = cfq_exit_queue,
4147 .icq_size = sizeof(struct cfq_io_cq),
4148 .icq_align = __alignof__(struct cfq_io_cq),
4149 .elevator_attrs = cfq_attrs,
4150 .elevator_name = "cfq",
4151 .elevator_owner = THIS_MODULE,
4154 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4155 static struct blkio_policy_type blkio_policy_cfq = {
4157 .blkio_init_group_fn = cfq_init_blkio_group,
4158 .blkio_reset_group_stats_fn = cfqg_stats_reset,
4160 .plid = BLKIO_POLICY_PROP,
4161 .pdata_size = sizeof(struct cfq_group),
4162 .cftypes = cfq_blkcg_files,
4166 static int __init cfq_init(void)
4171 * could be 0 on HZ < 1000 setups
4173 if (!cfq_slice_async)
4174 cfq_slice_async = 1;
4175 if (!cfq_slice_idle)
4178 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4179 if (!cfq_group_idle)
4184 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4188 ret = elv_register(&iosched_cfq);
4190 kmem_cache_destroy(cfq_pool);
4194 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4195 blkio_policy_register(&blkio_policy_cfq);
4200 static void __exit cfq_exit(void)
4202 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4203 blkio_policy_unregister(&blkio_policy_cfq);
4205 elv_unregister(&iosched_cfq);
4206 kmem_cache_destroy(cfq_pool);
4209 module_init(cfq_init);
4210 module_exit(cfq_exit);
4212 MODULE_AUTHOR("Jens Axboe");
4213 MODULE_LICENSE("GPL");
4214 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");