2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
18 #include "blk-cgroup.h"
23 /* max queue in one round of service */
24 static const int cfq_quantum = 8;
25 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max = 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty = 2;
30 static const int cfq_slice_sync = HZ / 10;
31 static int cfq_slice_async = HZ / 25;
32 static const int cfq_slice_async_rq = 2;
33 static int cfq_slice_idle = HZ / 125;
34 static int cfq_group_idle = HZ / 125;
35 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36 static const int cfq_hist_divisor = 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache *cfq_pool;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
71 unsigned long last_end_request;
73 unsigned long ttime_total;
74 unsigned long ttime_samples;
75 unsigned long ttime_mean;
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight;
90 struct cfq_ttime ttime;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
96 * Per process-grouping structure
101 /* various state flags, see below */
103 /* parent cfq_data */
104 struct cfq_data *cfqd;
105 /* service_tree member */
106 struct rb_node rb_node;
107 /* service_tree key */
108 unsigned long rb_key;
109 /* prio tree member */
110 struct rb_node p_node;
111 /* prio tree root we belong to, if any */
112 struct rb_root *p_root;
113 /* sorted list of pending requests */
114 struct rb_root sort_list;
115 /* if fifo isn't expired, next request to serve */
116 struct request *next_rq;
117 /* requests queued in sort_list */
119 /* currently allocated requests */
121 /* fifo list of requests in sort_list */
122 struct list_head fifo;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start;
126 unsigned int allocated_slice;
127 unsigned int slice_dispatch;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start;
130 unsigned long slice_end;
133 /* pending priority requests */
135 /* number of requests that are on the dispatch list or inside driver */
138 /* io prio of this group */
139 unsigned short ioprio, org_ioprio;
140 unsigned short ioprio_class;
145 sector_t last_request_pos;
147 struct cfq_rb_root *service_tree;
148 struct cfq_queue *new_cfqq;
149 struct cfq_group *cfqg;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors;
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
166 * Second index in the service_trees.
170 SYNC_NOIDLE_WORKLOAD = 1,
175 #ifdef CONFIG_CFQ_GROUP_IOSCHED
176 /* total bytes transferred */
177 struct blkg_rwstat service_bytes;
178 /* total IOs serviced, post merge */
179 struct blkg_rwstat serviced;
180 /* number of ios merged */
181 struct blkg_rwstat merged;
182 /* total time spent on device in ns, may not be accurate w/ queueing */
183 struct blkg_rwstat service_time;
184 /* total time spent waiting in scheduler queue in ns */
185 struct blkg_rwstat wait_time;
186 /* number of IOs queued up */
187 struct blkg_rwstat queued;
188 /* total sectors transferred */
189 struct blkg_stat sectors;
190 /* total disk time and nr sectors dispatched by this group */
191 struct blkg_stat time;
192 #ifdef CONFIG_DEBUG_BLK_CGROUP
193 /* time not charged to this cgroup */
194 struct blkg_stat unaccounted_time;
195 /* sum of number of ios queued across all samples */
196 struct blkg_stat avg_queue_size_sum;
197 /* count of samples taken for average */
198 struct blkg_stat avg_queue_size_samples;
199 /* how many times this group has been removed from service tree */
200 struct blkg_stat dequeue;
201 /* total time spent waiting for it to be assigned a timeslice. */
202 struct blkg_stat group_wait_time;
203 /* time spent idling for this blkcg_gq */
204 struct blkg_stat idle_time;
205 /* total time with empty current active q with other requests queued */
206 struct blkg_stat empty_time;
207 /* fields after this shouldn't be cleared on stat reset */
208 uint64_t start_group_wait_time;
209 uint64_t start_idle_time;
210 uint64_t start_empty_time;
212 #endif /* CONFIG_DEBUG_BLK_CGROUP */
213 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
216 /* This is per cgroup per device grouping structure */
218 /* must be the first member */
219 struct blkg_policy_data pd;
221 /* group service_tree member */
222 struct rb_node rb_node;
224 /* group service_tree key */
227 unsigned int new_weight;
228 unsigned int dev_weight;
230 /* number of cfqq currently on this group */
234 * Per group busy queues average. Useful for workload slice calc. We
235 * create the array for each prio class but at run time it is used
236 * only for RT and BE class and slot for IDLE class remains unused.
237 * This is primarily done to avoid confusion and a gcc warning.
239 unsigned int busy_queues_avg[CFQ_PRIO_NR];
241 * rr lists of queues with requests. We maintain service trees for
242 * RT and BE classes. These trees are subdivided in subclasses
243 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
244 * class there is no subclassification and all the cfq queues go on
245 * a single tree service_tree_idle.
246 * Counts are embedded in the cfq_rb_root
248 struct cfq_rb_root service_trees[2][3];
249 struct cfq_rb_root service_tree_idle;
251 unsigned long saved_wl_slice;
252 enum wl_type_t saved_wl_type;
253 enum wl_class_t saved_wl_class;
255 /* number of requests that are on the dispatch list or inside driver */
257 struct cfq_ttime ttime;
258 struct cfqg_stats stats;
262 struct io_cq icq; /* must be the first member */
263 struct cfq_queue *cfqq[2];
264 struct cfq_ttime ttime;
265 int ioprio; /* the current ioprio */
266 #ifdef CONFIG_CFQ_GROUP_IOSCHED
267 uint64_t blkcg_id; /* the current blkcg ID */
272 * Per block device queue structure
275 struct request_queue *queue;
276 /* Root service tree for cfq_groups */
277 struct cfq_rb_root grp_service_tree;
278 struct cfq_group *root_group;
281 * The priority currently being served
283 enum wl_class_t serving_wl_class;
284 enum wl_type_t serving_wl_type;
285 unsigned long workload_expires;
286 struct cfq_group *serving_group;
289 * Each priority tree is sorted by next_request position. These
290 * trees are used when determining if two or more queues are
291 * interleaving requests (see cfq_close_cooperator).
293 struct rb_root prio_trees[CFQ_PRIO_LISTS];
295 unsigned int busy_queues;
296 unsigned int busy_sync_queues;
302 * queue-depth detection
308 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
309 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
312 int hw_tag_est_depth;
313 unsigned int hw_tag_samples;
316 * idle window management
318 struct timer_list idle_slice_timer;
319 struct work_struct unplug_work;
321 struct cfq_queue *active_queue;
322 struct cfq_io_cq *active_cic;
325 * async queue for each priority case
327 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
328 struct cfq_queue *async_idle_cfqq;
330 sector_t last_position;
333 * tunables, see top of file
335 unsigned int cfq_quantum;
336 unsigned int cfq_fifo_expire[2];
337 unsigned int cfq_back_penalty;
338 unsigned int cfq_back_max;
339 unsigned int cfq_slice[2];
340 unsigned int cfq_slice_async_rq;
341 unsigned int cfq_slice_idle;
342 unsigned int cfq_group_idle;
343 unsigned int cfq_latency;
344 unsigned int cfq_target_latency;
347 * Fallback dummy cfqq for extreme OOM conditions
349 struct cfq_queue oom_cfqq;
351 unsigned long last_delayed_sync;
354 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
356 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
357 enum wl_class_t class,
363 if (class == IDLE_WORKLOAD)
364 return &cfqg->service_tree_idle;
366 return &cfqg->service_trees[class][type];
369 enum cfqq_state_flags {
370 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
371 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
372 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
373 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
374 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
375 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
376 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
377 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
378 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
379 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
380 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
381 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
382 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
385 #define CFQ_CFQQ_FNS(name) \
386 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
388 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
390 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
392 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
394 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
396 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
400 CFQ_CFQQ_FNS(wait_request);
401 CFQ_CFQQ_FNS(must_dispatch);
402 CFQ_CFQQ_FNS(must_alloc_slice);
403 CFQ_CFQQ_FNS(fifo_expire);
404 CFQ_CFQQ_FNS(idle_window);
405 CFQ_CFQQ_FNS(prio_changed);
406 CFQ_CFQQ_FNS(slice_new);
409 CFQ_CFQQ_FNS(split_coop);
411 CFQ_CFQQ_FNS(wait_busy);
414 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
416 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
419 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
421 return pd_to_blkg(&cfqg->pd);
424 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
426 /* cfqg stats flags */
427 enum cfqg_stats_flags {
428 CFQG_stats_waiting = 0,
433 #define CFQG_FLAG_FNS(name) \
434 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
436 stats->flags |= (1 << CFQG_stats_##name); \
438 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
440 stats->flags &= ~(1 << CFQG_stats_##name); \
442 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
444 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
447 CFQG_FLAG_FNS(waiting)
448 CFQG_FLAG_FNS(idling)
452 /* This should be called with the queue_lock held. */
453 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
455 unsigned long long now;
457 if (!cfqg_stats_waiting(stats))
461 if (time_after64(now, stats->start_group_wait_time))
462 blkg_stat_add(&stats->group_wait_time,
463 now - stats->start_group_wait_time);
464 cfqg_stats_clear_waiting(stats);
467 /* This should be called with the queue_lock held. */
468 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
469 struct cfq_group *curr_cfqg)
471 struct cfqg_stats *stats = &cfqg->stats;
473 if (cfqg_stats_waiting(stats))
475 if (cfqg == curr_cfqg)
477 stats->start_group_wait_time = sched_clock();
478 cfqg_stats_mark_waiting(stats);
481 /* This should be called with the queue_lock held. */
482 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
484 unsigned long long now;
486 if (!cfqg_stats_empty(stats))
490 if (time_after64(now, stats->start_empty_time))
491 blkg_stat_add(&stats->empty_time,
492 now - stats->start_empty_time);
493 cfqg_stats_clear_empty(stats);
496 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
498 blkg_stat_add(&cfqg->stats.dequeue, 1);
501 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
503 struct cfqg_stats *stats = &cfqg->stats;
505 if (blkg_rwstat_sum(&stats->queued))
509 * group is already marked empty. This can happen if cfqq got new
510 * request in parent group and moved to this group while being added
511 * to service tree. Just ignore the event and move on.
513 if (cfqg_stats_empty(stats))
516 stats->start_empty_time = sched_clock();
517 cfqg_stats_mark_empty(stats);
520 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
522 struct cfqg_stats *stats = &cfqg->stats;
524 if (cfqg_stats_idling(stats)) {
525 unsigned long long now = sched_clock();
527 if (time_after64(now, stats->start_idle_time))
528 blkg_stat_add(&stats->idle_time,
529 now - stats->start_idle_time);
530 cfqg_stats_clear_idling(stats);
534 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
536 struct cfqg_stats *stats = &cfqg->stats;
538 BUG_ON(cfqg_stats_idling(stats));
540 stats->start_idle_time = sched_clock();
541 cfqg_stats_mark_idling(stats);
544 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
546 struct cfqg_stats *stats = &cfqg->stats;
548 blkg_stat_add(&stats->avg_queue_size_sum,
549 blkg_rwstat_sum(&stats->queued));
550 blkg_stat_add(&stats->avg_queue_size_samples, 1);
551 cfqg_stats_update_group_wait_time(stats);
554 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
556 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
557 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
558 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
559 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
560 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
561 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
562 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
564 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
566 #ifdef CONFIG_CFQ_GROUP_IOSCHED
568 static struct blkcg_policy blkcg_policy_cfq;
570 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
572 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
575 static inline void cfqg_get(struct cfq_group *cfqg)
577 return blkg_get(cfqg_to_blkg(cfqg));
580 static inline void cfqg_put(struct cfq_group *cfqg)
582 return blkg_put(cfqg_to_blkg(cfqg));
585 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
588 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
589 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
590 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
594 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
597 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
598 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
601 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
602 struct cfq_group *curr_cfqg, int rw)
604 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
605 cfqg_stats_end_empty_time(&cfqg->stats);
606 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
609 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
610 unsigned long time, unsigned long unaccounted_time)
612 blkg_stat_add(&cfqg->stats.time, time);
613 #ifdef CONFIG_DEBUG_BLK_CGROUP
614 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
618 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
620 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
623 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
625 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
628 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
629 uint64_t bytes, int rw)
631 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
632 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
633 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
636 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
637 uint64_t start_time, uint64_t io_start_time, int rw)
639 struct cfqg_stats *stats = &cfqg->stats;
640 unsigned long long now = sched_clock();
642 if (time_after64(now, io_start_time))
643 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
644 if (time_after64(io_start_time, start_time))
645 blkg_rwstat_add(&stats->wait_time, rw,
646 io_start_time - start_time);
649 static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
651 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
652 struct cfqg_stats *stats = &cfqg->stats;
654 /* queued stats shouldn't be cleared */
655 blkg_rwstat_reset(&stats->service_bytes);
656 blkg_rwstat_reset(&stats->serviced);
657 blkg_rwstat_reset(&stats->merged);
658 blkg_rwstat_reset(&stats->service_time);
659 blkg_rwstat_reset(&stats->wait_time);
660 blkg_stat_reset(&stats->time);
661 #ifdef CONFIG_DEBUG_BLK_CGROUP
662 blkg_stat_reset(&stats->unaccounted_time);
663 blkg_stat_reset(&stats->avg_queue_size_sum);
664 blkg_stat_reset(&stats->avg_queue_size_samples);
665 blkg_stat_reset(&stats->dequeue);
666 blkg_stat_reset(&stats->group_wait_time);
667 blkg_stat_reset(&stats->idle_time);
668 blkg_stat_reset(&stats->empty_time);
672 #else /* CONFIG_CFQ_GROUP_IOSCHED */
674 static inline void cfqg_get(struct cfq_group *cfqg) { }
675 static inline void cfqg_put(struct cfq_group *cfqg) { }
677 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
678 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
679 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
681 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
682 struct cfq_group *curr_cfqg, int rw) { }
683 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
684 unsigned long time, unsigned long unaccounted_time) { }
685 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
686 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
687 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
688 uint64_t bytes, int rw) { }
689 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
690 uint64_t start_time, uint64_t io_start_time, int rw) { }
692 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
694 #define cfq_log(cfqd, fmt, args...) \
695 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
697 /* Traverses through cfq group service trees */
698 #define for_each_cfqg_st(cfqg, i, j, st) \
699 for (i = 0; i <= IDLE_WORKLOAD; i++) \
700 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
701 : &cfqg->service_tree_idle; \
702 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
703 (i == IDLE_WORKLOAD && j == 0); \
704 j++, st = i < IDLE_WORKLOAD ? \
705 &cfqg->service_trees[i][j]: NULL) \
707 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
708 struct cfq_ttime *ttime, bool group_idle)
711 if (!sample_valid(ttime->ttime_samples))
714 slice = cfqd->cfq_group_idle;
716 slice = cfqd->cfq_slice_idle;
717 return ttime->ttime_mean > slice;
720 static inline bool iops_mode(struct cfq_data *cfqd)
723 * If we are not idling on queues and it is a NCQ drive, parallel
724 * execution of requests is on and measuring time is not possible
725 * in most of the cases until and unless we drive shallower queue
726 * depths and that becomes a performance bottleneck. In such cases
727 * switch to start providing fairness in terms of number of IOs.
729 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
735 static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
737 if (cfq_class_idle(cfqq))
738 return IDLE_WORKLOAD;
739 if (cfq_class_rt(cfqq))
745 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
747 if (!cfq_cfqq_sync(cfqq))
748 return ASYNC_WORKLOAD;
749 if (!cfq_cfqq_idle_window(cfqq))
750 return SYNC_NOIDLE_WORKLOAD;
751 return SYNC_WORKLOAD;
754 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
755 struct cfq_data *cfqd,
756 struct cfq_group *cfqg)
758 if (wl_class == IDLE_WORKLOAD)
759 return cfqg->service_tree_idle.count;
761 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
762 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
763 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
766 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
767 struct cfq_group *cfqg)
769 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
770 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
773 static void cfq_dispatch_insert(struct request_queue *, struct request *);
774 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
775 struct cfq_io_cq *cic, struct bio *bio,
778 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
780 /* cic->icq is the first member, %NULL will convert to %NULL */
781 return container_of(icq, struct cfq_io_cq, icq);
784 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
785 struct io_context *ioc)
788 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
792 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
794 return cic->cfqq[is_sync];
797 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
800 cic->cfqq[is_sync] = cfqq;
803 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
805 return cic->icq.q->elevator->elevator_data;
809 * We regard a request as SYNC, if it's either a read or has the SYNC bit
810 * set (in which case it could also be direct WRITE).
812 static inline bool cfq_bio_sync(struct bio *bio)
814 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
818 * scheduler run of queue, if there are requests pending and no one in the
819 * driver that will restart queueing
821 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
823 if (cfqd->busy_queues) {
824 cfq_log(cfqd, "schedule dispatch");
825 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
830 * Scale schedule slice based on io priority. Use the sync time slice only
831 * if a queue is marked sync and has sync io queued. A sync queue with async
832 * io only, should not get full sync slice length.
834 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
837 const int base_slice = cfqd->cfq_slice[sync];
839 WARN_ON(prio >= IOPRIO_BE_NR);
841 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
845 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
847 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
850 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
852 u64 d = delta << CFQ_SERVICE_SHIFT;
854 d = d * CFQ_WEIGHT_DEFAULT;
855 do_div(d, cfqg->weight);
859 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
861 s64 delta = (s64)(vdisktime - min_vdisktime);
863 min_vdisktime = vdisktime;
865 return min_vdisktime;
868 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
870 s64 delta = (s64)(vdisktime - min_vdisktime);
872 min_vdisktime = vdisktime;
874 return min_vdisktime;
877 static void update_min_vdisktime(struct cfq_rb_root *st)
879 struct cfq_group *cfqg;
882 cfqg = rb_entry_cfqg(st->left);
883 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
889 * get averaged number of queues of RT/BE priority.
890 * average is updated, with a formula that gives more weight to higher numbers,
891 * to quickly follows sudden increases and decrease slowly
894 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
895 struct cfq_group *cfqg, bool rt)
897 unsigned min_q, max_q;
898 unsigned mult = cfq_hist_divisor - 1;
899 unsigned round = cfq_hist_divisor / 2;
900 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
902 min_q = min(cfqg->busy_queues_avg[rt], busy);
903 max_q = max(cfqg->busy_queues_avg[rt], busy);
904 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
906 return cfqg->busy_queues_avg[rt];
909 static inline unsigned
910 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
912 struct cfq_rb_root *st = &cfqd->grp_service_tree;
914 return cfqd->cfq_target_latency * cfqg->weight / st->total_weight;
917 static inline unsigned
918 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
920 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
921 if (cfqd->cfq_latency) {
923 * interested queues (we consider only the ones with the same
924 * priority class in the cfq group)
926 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
928 unsigned sync_slice = cfqd->cfq_slice[1];
929 unsigned expect_latency = sync_slice * iq;
930 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
932 if (expect_latency > group_slice) {
933 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
934 /* scale low_slice according to IO priority
935 * and sync vs async */
937 min(slice, base_low_slice * slice / sync_slice);
938 /* the adapted slice value is scaled to fit all iqs
939 * into the target latency */
940 slice = max(slice * group_slice / expect_latency,
948 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
950 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
952 cfqq->slice_start = jiffies;
953 cfqq->slice_end = jiffies + slice;
954 cfqq->allocated_slice = slice;
955 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
959 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
960 * isn't valid until the first request from the dispatch is activated
961 * and the slice time set.
963 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
965 if (cfq_cfqq_slice_new(cfqq))
967 if (time_before(jiffies, cfqq->slice_end))
974 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
975 * We choose the request that is closest to the head right now. Distance
976 * behind the head is penalized and only allowed to a certain extent.
978 static struct request *
979 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
981 sector_t s1, s2, d1 = 0, d2 = 0;
982 unsigned long back_max;
983 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
984 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
985 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
987 if (rq1 == NULL || rq1 == rq2)
992 if (rq_is_sync(rq1) != rq_is_sync(rq2))
993 return rq_is_sync(rq1) ? rq1 : rq2;
995 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
996 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
998 s1 = blk_rq_pos(rq1);
999 s2 = blk_rq_pos(rq2);
1002 * by definition, 1KiB is 2 sectors
1004 back_max = cfqd->cfq_back_max * 2;
1007 * Strict one way elevator _except_ in the case where we allow
1008 * short backward seeks which are biased as twice the cost of a
1009 * similar forward seek.
1013 else if (s1 + back_max >= last)
1014 d1 = (last - s1) * cfqd->cfq_back_penalty;
1016 wrap |= CFQ_RQ1_WRAP;
1020 else if (s2 + back_max >= last)
1021 d2 = (last - s2) * cfqd->cfq_back_penalty;
1023 wrap |= CFQ_RQ2_WRAP;
1025 /* Found required data */
1028 * By doing switch() on the bit mask "wrap" we avoid having to
1029 * check two variables for all permutations: --> faster!
1032 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1048 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1051 * Since both rqs are wrapped,
1052 * start with the one that's further behind head
1053 * (--> only *one* back seek required),
1054 * since back seek takes more time than forward.
1064 * The below is leftmost cache rbtree addon
1066 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1068 /* Service tree is empty */
1073 root->left = rb_first(&root->rb);
1076 return rb_entry(root->left, struct cfq_queue, rb_node);
1081 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1084 root->left = rb_first(&root->rb);
1087 return rb_entry_cfqg(root->left);
1092 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1098 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1100 if (root->left == n)
1102 rb_erase_init(n, &root->rb);
1107 * would be nice to take fifo expire time into account as well
1109 static struct request *
1110 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1111 struct request *last)
1113 struct rb_node *rbnext = rb_next(&last->rb_node);
1114 struct rb_node *rbprev = rb_prev(&last->rb_node);
1115 struct request *next = NULL, *prev = NULL;
1117 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1120 prev = rb_entry_rq(rbprev);
1123 next = rb_entry_rq(rbnext);
1125 rbnext = rb_first(&cfqq->sort_list);
1126 if (rbnext && rbnext != &last->rb_node)
1127 next = rb_entry_rq(rbnext);
1130 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1133 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1134 struct cfq_queue *cfqq)
1137 * just an approximation, should be ok.
1139 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1140 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1144 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1146 return cfqg->vdisktime - st->min_vdisktime;
1150 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1152 struct rb_node **node = &st->rb.rb_node;
1153 struct rb_node *parent = NULL;
1154 struct cfq_group *__cfqg;
1155 s64 key = cfqg_key(st, cfqg);
1158 while (*node != NULL) {
1160 __cfqg = rb_entry_cfqg(parent);
1162 if (key < cfqg_key(st, __cfqg))
1163 node = &parent->rb_left;
1165 node = &parent->rb_right;
1171 st->left = &cfqg->rb_node;
1173 rb_link_node(&cfqg->rb_node, parent, node);
1174 rb_insert_color(&cfqg->rb_node, &st->rb);
1178 cfq_update_group_weight(struct cfq_group *cfqg)
1180 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1181 if (cfqg->new_weight) {
1182 cfqg->weight = cfqg->new_weight;
1183 cfqg->new_weight = 0;
1188 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1190 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1192 cfq_update_group_weight(cfqg);
1193 __cfq_group_service_tree_add(st, cfqg);
1194 st->total_weight += cfqg->weight;
1198 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1200 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1201 struct cfq_group *__cfqg;
1205 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1209 * Currently put the group at the end. Later implement something
1210 * so that groups get lesser vtime based on their weights, so that
1211 * if group does not loose all if it was not continuously backlogged.
1213 n = rb_last(&st->rb);
1215 __cfqg = rb_entry_cfqg(n);
1216 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1218 cfqg->vdisktime = st->min_vdisktime;
1219 cfq_group_service_tree_add(st, cfqg);
1223 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1225 st->total_weight -= cfqg->weight;
1226 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1227 cfq_rb_erase(&cfqg->rb_node, st);
1231 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1233 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1235 BUG_ON(cfqg->nr_cfqq < 1);
1238 /* If there are other cfq queues under this group, don't delete it */
1242 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1243 cfq_group_service_tree_del(st, cfqg);
1244 cfqg->saved_wl_slice = 0;
1245 cfqg_stats_update_dequeue(cfqg);
1248 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1249 unsigned int *unaccounted_time)
1251 unsigned int slice_used;
1254 * Queue got expired before even a single request completed or
1255 * got expired immediately after first request completion.
1257 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1259 * Also charge the seek time incurred to the group, otherwise
1260 * if there are mutiple queues in the group, each can dispatch
1261 * a single request on seeky media and cause lots of seek time
1262 * and group will never know it.
1264 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1267 slice_used = jiffies - cfqq->slice_start;
1268 if (slice_used > cfqq->allocated_slice) {
1269 *unaccounted_time = slice_used - cfqq->allocated_slice;
1270 slice_used = cfqq->allocated_slice;
1272 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1273 *unaccounted_time += cfqq->slice_start -
1274 cfqq->dispatch_start;
1280 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1281 struct cfq_queue *cfqq)
1283 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1284 unsigned int used_sl, charge, unaccounted_sl = 0;
1285 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1286 - cfqg->service_tree_idle.count;
1288 BUG_ON(nr_sync < 0);
1289 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1291 if (iops_mode(cfqd))
1292 charge = cfqq->slice_dispatch;
1293 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1294 charge = cfqq->allocated_slice;
1296 /* Can't update vdisktime while group is on service tree */
1297 cfq_group_service_tree_del(st, cfqg);
1298 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1299 /* If a new weight was requested, update now, off tree */
1300 cfq_group_service_tree_add(st, cfqg);
1302 /* This group is being expired. Save the context */
1303 if (time_after(cfqd->workload_expires, jiffies)) {
1304 cfqg->saved_wl_slice = cfqd->workload_expires
1306 cfqg->saved_wl_type = cfqd->serving_wl_type;
1307 cfqg->saved_wl_class = cfqd->serving_wl_class;
1309 cfqg->saved_wl_slice = 0;
1311 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1313 cfq_log_cfqq(cfqq->cfqd, cfqq,
1314 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1315 used_sl, cfqq->slice_dispatch, charge,
1316 iops_mode(cfqd), cfqq->nr_sectors);
1317 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1318 cfqg_stats_set_start_empty_time(cfqg);
1322 * cfq_init_cfqg_base - initialize base part of a cfq_group
1323 * @cfqg: cfq_group to initialize
1325 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1326 * is enabled or not.
1328 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1330 struct cfq_rb_root *st;
1333 for_each_cfqg_st(cfqg, i, j, st)
1335 RB_CLEAR_NODE(&cfqg->rb_node);
1337 cfqg->ttime.last_end_request = jiffies;
1340 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1341 static void cfq_pd_init(struct blkcg_gq *blkg)
1343 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1345 cfq_init_cfqg_base(cfqg);
1346 cfqg->weight = blkg->blkcg->cfq_weight;
1350 * Search for the cfq group current task belongs to. request_queue lock must
1353 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1354 struct blkcg *blkcg)
1356 struct request_queue *q = cfqd->queue;
1357 struct cfq_group *cfqg = NULL;
1359 /* avoid lookup for the common case where there's no blkcg */
1360 if (blkcg == &blkcg_root) {
1361 cfqg = cfqd->root_group;
1363 struct blkcg_gq *blkg;
1365 blkg = blkg_lookup_create(blkcg, q);
1367 cfqg = blkg_to_cfqg(blkg);
1373 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1375 /* Currently, all async queues are mapped to root group */
1376 if (!cfq_cfqq_sync(cfqq))
1377 cfqg = cfqq->cfqd->root_group;
1380 /* cfqq reference on cfqg */
1384 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1385 struct blkg_policy_data *pd, int off)
1387 struct cfq_group *cfqg = pd_to_cfqg(pd);
1389 if (!cfqg->dev_weight)
1391 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1394 static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1395 struct seq_file *sf)
1397 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1398 cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
1403 static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1404 struct seq_file *sf)
1406 seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
1410 static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1413 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1414 struct blkg_conf_ctx ctx;
1415 struct cfq_group *cfqg;
1418 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1423 cfqg = blkg_to_cfqg(ctx.blkg);
1424 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1425 cfqg->dev_weight = ctx.v;
1426 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1430 blkg_conf_finish(&ctx);
1434 static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1436 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1437 struct blkcg_gq *blkg;
1438 struct hlist_node *n;
1440 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1443 spin_lock_irq(&blkcg->lock);
1444 blkcg->cfq_weight = (unsigned int)val;
1446 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1447 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1449 if (cfqg && !cfqg->dev_weight)
1450 cfqg->new_weight = blkcg->cfq_weight;
1453 spin_unlock_irq(&blkcg->lock);
1457 static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
1458 struct seq_file *sf)
1460 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1462 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
1463 cft->private, false);
1467 static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
1468 struct seq_file *sf)
1470 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1472 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
1473 cft->private, true);
1477 #ifdef CONFIG_DEBUG_BLK_CGROUP
1478 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1479 struct blkg_policy_data *pd, int off)
1481 struct cfq_group *cfqg = pd_to_cfqg(pd);
1482 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1486 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1489 __blkg_prfill_u64(sf, pd, v);
1493 /* print avg_queue_size */
1494 static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1495 struct seq_file *sf)
1497 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1499 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1500 &blkcg_policy_cfq, 0, false);
1503 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1505 static struct cftype cfq_blkcg_files[] = {
1507 .name = "weight_device",
1508 .read_seq_string = cfqg_print_weight_device,
1509 .write_string = cfqg_set_weight_device,
1510 .max_write_len = 256,
1514 .read_seq_string = cfq_print_weight,
1515 .write_u64 = cfq_set_weight,
1519 .private = offsetof(struct cfq_group, stats.time),
1520 .read_seq_string = cfqg_print_stat,
1524 .private = offsetof(struct cfq_group, stats.sectors),
1525 .read_seq_string = cfqg_print_stat,
1528 .name = "io_service_bytes",
1529 .private = offsetof(struct cfq_group, stats.service_bytes),
1530 .read_seq_string = cfqg_print_rwstat,
1533 .name = "io_serviced",
1534 .private = offsetof(struct cfq_group, stats.serviced),
1535 .read_seq_string = cfqg_print_rwstat,
1538 .name = "io_service_time",
1539 .private = offsetof(struct cfq_group, stats.service_time),
1540 .read_seq_string = cfqg_print_rwstat,
1543 .name = "io_wait_time",
1544 .private = offsetof(struct cfq_group, stats.wait_time),
1545 .read_seq_string = cfqg_print_rwstat,
1548 .name = "io_merged",
1549 .private = offsetof(struct cfq_group, stats.merged),
1550 .read_seq_string = cfqg_print_rwstat,
1553 .name = "io_queued",
1554 .private = offsetof(struct cfq_group, stats.queued),
1555 .read_seq_string = cfqg_print_rwstat,
1557 #ifdef CONFIG_DEBUG_BLK_CGROUP
1559 .name = "avg_queue_size",
1560 .read_seq_string = cfqg_print_avg_queue_size,
1563 .name = "group_wait_time",
1564 .private = offsetof(struct cfq_group, stats.group_wait_time),
1565 .read_seq_string = cfqg_print_stat,
1568 .name = "idle_time",
1569 .private = offsetof(struct cfq_group, stats.idle_time),
1570 .read_seq_string = cfqg_print_stat,
1573 .name = "empty_time",
1574 .private = offsetof(struct cfq_group, stats.empty_time),
1575 .read_seq_string = cfqg_print_stat,
1579 .private = offsetof(struct cfq_group, stats.dequeue),
1580 .read_seq_string = cfqg_print_stat,
1583 .name = "unaccounted_time",
1584 .private = offsetof(struct cfq_group, stats.unaccounted_time),
1585 .read_seq_string = cfqg_print_stat,
1587 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1590 #else /* GROUP_IOSCHED */
1591 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1592 struct blkcg *blkcg)
1594 return cfqd->root_group;
1598 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1602 #endif /* GROUP_IOSCHED */
1605 * The cfqd->service_trees holds all pending cfq_queue's that have
1606 * requests waiting to be processed. It is sorted in the order that
1607 * we will service the queues.
1609 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1612 struct rb_node **p, *parent;
1613 struct cfq_queue *__cfqq;
1614 unsigned long rb_key;
1615 struct cfq_rb_root *st;
1619 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
1620 if (cfq_class_idle(cfqq)) {
1621 rb_key = CFQ_IDLE_DELAY;
1622 parent = rb_last(&st->rb);
1623 if (parent && parent != &cfqq->rb_node) {
1624 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1625 rb_key += __cfqq->rb_key;
1628 } else if (!add_front) {
1630 * Get our rb key offset. Subtract any residual slice
1631 * value carried from last service. A negative resid
1632 * count indicates slice overrun, and this should position
1633 * the next service time further away in the tree.
1635 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1636 rb_key -= cfqq->slice_resid;
1637 cfqq->slice_resid = 0;
1640 __cfqq = cfq_rb_first(st);
1641 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1644 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1647 * same position, nothing more to do
1649 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
1652 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1653 cfqq->service_tree = NULL;
1658 cfqq->service_tree = st;
1659 p = &st->rb.rb_node;
1662 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1665 * sort by key, that represents service time.
1667 if (time_before(rb_key, __cfqq->rb_key))
1668 p = &parent->rb_left;
1670 p = &parent->rb_right;
1676 st->left = &cfqq->rb_node;
1678 cfqq->rb_key = rb_key;
1679 rb_link_node(&cfqq->rb_node, parent, p);
1680 rb_insert_color(&cfqq->rb_node, &st->rb);
1682 if (add_front || !new_cfqq)
1684 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1687 static struct cfq_queue *
1688 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1689 sector_t sector, struct rb_node **ret_parent,
1690 struct rb_node ***rb_link)
1692 struct rb_node **p, *parent;
1693 struct cfq_queue *cfqq = NULL;
1701 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1704 * Sort strictly based on sector. Smallest to the left,
1705 * largest to the right.
1707 if (sector > blk_rq_pos(cfqq->next_rq))
1708 n = &(*p)->rb_right;
1709 else if (sector < blk_rq_pos(cfqq->next_rq))
1717 *ret_parent = parent;
1723 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1725 struct rb_node **p, *parent;
1726 struct cfq_queue *__cfqq;
1729 rb_erase(&cfqq->p_node, cfqq->p_root);
1730 cfqq->p_root = NULL;
1733 if (cfq_class_idle(cfqq))
1738 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1739 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1740 blk_rq_pos(cfqq->next_rq), &parent, &p);
1742 rb_link_node(&cfqq->p_node, parent, p);
1743 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1745 cfqq->p_root = NULL;
1749 * Update cfqq's position in the service tree.
1751 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1754 * Resorting requires the cfqq to be on the RR list already.
1756 if (cfq_cfqq_on_rr(cfqq)) {
1757 cfq_service_tree_add(cfqd, cfqq, 0);
1758 cfq_prio_tree_add(cfqd, cfqq);
1763 * add to busy list of queues for service, trying to be fair in ordering
1764 * the pending list according to last request service
1766 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1768 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1769 BUG_ON(cfq_cfqq_on_rr(cfqq));
1770 cfq_mark_cfqq_on_rr(cfqq);
1771 cfqd->busy_queues++;
1772 if (cfq_cfqq_sync(cfqq))
1773 cfqd->busy_sync_queues++;
1775 cfq_resort_rr_list(cfqd, cfqq);
1779 * Called when the cfqq no longer has requests pending, remove it from
1782 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1784 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1785 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1786 cfq_clear_cfqq_on_rr(cfqq);
1788 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1789 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1790 cfqq->service_tree = NULL;
1793 rb_erase(&cfqq->p_node, cfqq->p_root);
1794 cfqq->p_root = NULL;
1797 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1798 BUG_ON(!cfqd->busy_queues);
1799 cfqd->busy_queues--;
1800 if (cfq_cfqq_sync(cfqq))
1801 cfqd->busy_sync_queues--;
1805 * rb tree support functions
1807 static void cfq_del_rq_rb(struct request *rq)
1809 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1810 const int sync = rq_is_sync(rq);
1812 BUG_ON(!cfqq->queued[sync]);
1813 cfqq->queued[sync]--;
1815 elv_rb_del(&cfqq->sort_list, rq);
1817 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1819 * Queue will be deleted from service tree when we actually
1820 * expire it later. Right now just remove it from prio tree
1824 rb_erase(&cfqq->p_node, cfqq->p_root);
1825 cfqq->p_root = NULL;
1830 static void cfq_add_rq_rb(struct request *rq)
1832 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1833 struct cfq_data *cfqd = cfqq->cfqd;
1834 struct request *prev;
1836 cfqq->queued[rq_is_sync(rq)]++;
1838 elv_rb_add(&cfqq->sort_list, rq);
1840 if (!cfq_cfqq_on_rr(cfqq))
1841 cfq_add_cfqq_rr(cfqd, cfqq);
1844 * check if this request is a better next-serve candidate
1846 prev = cfqq->next_rq;
1847 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1850 * adjust priority tree position, if ->next_rq changes
1852 if (prev != cfqq->next_rq)
1853 cfq_prio_tree_add(cfqd, cfqq);
1855 BUG_ON(!cfqq->next_rq);
1858 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1860 elv_rb_del(&cfqq->sort_list, rq);
1861 cfqq->queued[rq_is_sync(rq)]--;
1862 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1864 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1868 static struct request *
1869 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1871 struct task_struct *tsk = current;
1872 struct cfq_io_cq *cic;
1873 struct cfq_queue *cfqq;
1875 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1879 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1881 sector_t sector = bio->bi_sector + bio_sectors(bio);
1883 return elv_rb_find(&cfqq->sort_list, sector);
1889 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1891 struct cfq_data *cfqd = q->elevator->elevator_data;
1893 cfqd->rq_in_driver++;
1894 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1895 cfqd->rq_in_driver);
1897 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1900 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1902 struct cfq_data *cfqd = q->elevator->elevator_data;
1904 WARN_ON(!cfqd->rq_in_driver);
1905 cfqd->rq_in_driver--;
1906 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1907 cfqd->rq_in_driver);
1910 static void cfq_remove_request(struct request *rq)
1912 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1914 if (cfqq->next_rq == rq)
1915 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1917 list_del_init(&rq->queuelist);
1920 cfqq->cfqd->rq_queued--;
1921 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1922 if (rq->cmd_flags & REQ_PRIO) {
1923 WARN_ON(!cfqq->prio_pending);
1924 cfqq->prio_pending--;
1928 static int cfq_merge(struct request_queue *q, struct request **req,
1931 struct cfq_data *cfqd = q->elevator->elevator_data;
1932 struct request *__rq;
1934 __rq = cfq_find_rq_fmerge(cfqd, bio);
1935 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1937 return ELEVATOR_FRONT_MERGE;
1940 return ELEVATOR_NO_MERGE;
1943 static void cfq_merged_request(struct request_queue *q, struct request *req,
1946 if (type == ELEVATOR_FRONT_MERGE) {
1947 struct cfq_queue *cfqq = RQ_CFQQ(req);
1949 cfq_reposition_rq_rb(cfqq, req);
1953 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1956 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1960 cfq_merged_requests(struct request_queue *q, struct request *rq,
1961 struct request *next)
1963 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1964 struct cfq_data *cfqd = q->elevator->elevator_data;
1967 * reposition in fifo if next is older than rq
1969 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1970 time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
1971 cfqq == RQ_CFQQ(next)) {
1972 list_move(&rq->queuelist, &next->queuelist);
1973 rq_set_fifo_time(rq, rq_fifo_time(next));
1976 if (cfqq->next_rq == next)
1978 cfq_remove_request(next);
1979 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1981 cfqq = RQ_CFQQ(next);
1983 * all requests of this queue are merged to other queues, delete it
1984 * from the service tree. If it's the active_queue,
1985 * cfq_dispatch_requests() will choose to expire it or do idle
1987 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1988 cfqq != cfqd->active_queue)
1989 cfq_del_cfqq_rr(cfqd, cfqq);
1992 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1995 struct cfq_data *cfqd = q->elevator->elevator_data;
1996 struct cfq_io_cq *cic;
1997 struct cfq_queue *cfqq;
2000 * Disallow merge of a sync bio into an async request.
2002 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2006 * Lookup the cfqq that this bio will be queued with and allow
2007 * merge only if rq is queued there.
2009 cic = cfq_cic_lookup(cfqd, current->io_context);
2013 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2014 return cfqq == RQ_CFQQ(rq);
2017 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2019 del_timer(&cfqd->idle_slice_timer);
2020 cfqg_stats_update_idle_time(cfqq->cfqg);
2023 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2024 struct cfq_queue *cfqq)
2027 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2028 cfqd->serving_wl_class, cfqd->serving_wl_type);
2029 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2030 cfqq->slice_start = 0;
2031 cfqq->dispatch_start = jiffies;
2032 cfqq->allocated_slice = 0;
2033 cfqq->slice_end = 0;
2034 cfqq->slice_dispatch = 0;
2035 cfqq->nr_sectors = 0;
2037 cfq_clear_cfqq_wait_request(cfqq);
2038 cfq_clear_cfqq_must_dispatch(cfqq);
2039 cfq_clear_cfqq_must_alloc_slice(cfqq);
2040 cfq_clear_cfqq_fifo_expire(cfqq);
2041 cfq_mark_cfqq_slice_new(cfqq);
2043 cfq_del_timer(cfqd, cfqq);
2046 cfqd->active_queue = cfqq;
2050 * current cfqq expired its slice (or was too idle), select new one
2053 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2056 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2058 if (cfq_cfqq_wait_request(cfqq))
2059 cfq_del_timer(cfqd, cfqq);
2061 cfq_clear_cfqq_wait_request(cfqq);
2062 cfq_clear_cfqq_wait_busy(cfqq);
2065 * If this cfqq is shared between multiple processes, check to
2066 * make sure that those processes are still issuing I/Os within
2067 * the mean seek distance. If not, it may be time to break the
2068 * queues apart again.
2070 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2071 cfq_mark_cfqq_split_coop(cfqq);
2074 * store what was left of this slice, if the queue idled/timed out
2077 if (cfq_cfqq_slice_new(cfqq))
2078 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2080 cfqq->slice_resid = cfqq->slice_end - jiffies;
2081 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2084 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2086 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2087 cfq_del_cfqq_rr(cfqd, cfqq);
2089 cfq_resort_rr_list(cfqd, cfqq);
2091 if (cfqq == cfqd->active_queue)
2092 cfqd->active_queue = NULL;
2094 if (cfqd->active_cic) {
2095 put_io_context(cfqd->active_cic->icq.ioc);
2096 cfqd->active_cic = NULL;
2100 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2102 struct cfq_queue *cfqq = cfqd->active_queue;
2105 __cfq_slice_expired(cfqd, cfqq, timed_out);
2109 * Get next queue for service. Unless we have a queue preemption,
2110 * we'll simply select the first cfqq in the service tree.
2112 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2114 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2115 cfqd->serving_wl_class, cfqd->serving_wl_type);
2117 if (!cfqd->rq_queued)
2120 /* There is nothing to dispatch */
2123 if (RB_EMPTY_ROOT(&st->rb))
2125 return cfq_rb_first(st);
2128 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2130 struct cfq_group *cfqg;
2131 struct cfq_queue *cfqq;
2133 struct cfq_rb_root *st;
2135 if (!cfqd->rq_queued)
2138 cfqg = cfq_get_next_cfqg(cfqd);
2142 for_each_cfqg_st(cfqg, i, j, st)
2143 if ((cfqq = cfq_rb_first(st)) != NULL)
2149 * Get and set a new active queue for service.
2151 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2152 struct cfq_queue *cfqq)
2155 cfqq = cfq_get_next_queue(cfqd);
2157 __cfq_set_active_queue(cfqd, cfqq);
2161 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2164 if (blk_rq_pos(rq) >= cfqd->last_position)
2165 return blk_rq_pos(rq) - cfqd->last_position;
2167 return cfqd->last_position - blk_rq_pos(rq);
2170 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2173 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2176 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2177 struct cfq_queue *cur_cfqq)
2179 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2180 struct rb_node *parent, *node;
2181 struct cfq_queue *__cfqq;
2182 sector_t sector = cfqd->last_position;
2184 if (RB_EMPTY_ROOT(root))
2188 * First, if we find a request starting at the end of the last
2189 * request, choose it.
2191 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2196 * If the exact sector wasn't found, the parent of the NULL leaf
2197 * will contain the closest sector.
2199 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2200 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2203 if (blk_rq_pos(__cfqq->next_rq) < sector)
2204 node = rb_next(&__cfqq->p_node);
2206 node = rb_prev(&__cfqq->p_node);
2210 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2211 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2219 * cur_cfqq - passed in so that we don't decide that the current queue is
2220 * closely cooperating with itself.
2222 * So, basically we're assuming that that cur_cfqq has dispatched at least
2223 * one request, and that cfqd->last_position reflects a position on the disk
2224 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2227 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2228 struct cfq_queue *cur_cfqq)
2230 struct cfq_queue *cfqq;
2232 if (cfq_class_idle(cur_cfqq))
2234 if (!cfq_cfqq_sync(cur_cfqq))
2236 if (CFQQ_SEEKY(cur_cfqq))
2240 * Don't search priority tree if it's the only queue in the group.
2242 if (cur_cfqq->cfqg->nr_cfqq == 1)
2246 * We should notice if some of the queues are cooperating, eg
2247 * working closely on the same area of the disk. In that case,
2248 * we can group them together and don't waste time idling.
2250 cfqq = cfqq_close(cfqd, cur_cfqq);
2254 /* If new queue belongs to different cfq_group, don't choose it */
2255 if (cur_cfqq->cfqg != cfqq->cfqg)
2259 * It only makes sense to merge sync queues.
2261 if (!cfq_cfqq_sync(cfqq))
2263 if (CFQQ_SEEKY(cfqq))
2267 * Do not merge queues of different priority classes
2269 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2276 * Determine whether we should enforce idle window for this queue.
2279 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2281 enum wl_class_t wl_class = cfqq_class(cfqq);
2282 struct cfq_rb_root *st = cfqq->service_tree;
2287 if (!cfqd->cfq_slice_idle)
2290 /* We never do for idle class queues. */
2291 if (wl_class == IDLE_WORKLOAD)
2294 /* We do for queues that were marked with idle window flag. */
2295 if (cfq_cfqq_idle_window(cfqq) &&
2296 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2300 * Otherwise, we do only if they are the last ones
2301 * in their service tree.
2303 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2304 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2306 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2310 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2312 struct cfq_queue *cfqq = cfqd->active_queue;
2313 struct cfq_io_cq *cic;
2314 unsigned long sl, group_idle = 0;
2317 * SSD device without seek penalty, disable idling. But only do so
2318 * for devices that support queuing, otherwise we still have a problem
2319 * with sync vs async workloads.
2321 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2324 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2325 WARN_ON(cfq_cfqq_slice_new(cfqq));
2328 * idle is disabled, either manually or by past process history
2330 if (!cfq_should_idle(cfqd, cfqq)) {
2331 /* no queue idling. Check for group idling */
2332 if (cfqd->cfq_group_idle)
2333 group_idle = cfqd->cfq_group_idle;
2339 * still active requests from this queue, don't idle
2341 if (cfqq->dispatched)
2345 * task has exited, don't wait
2347 cic = cfqd->active_cic;
2348 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2352 * If our average think time is larger than the remaining time
2353 * slice, then don't idle. This avoids overrunning the allotted
2356 if (sample_valid(cic->ttime.ttime_samples) &&
2357 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2358 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2359 cic->ttime.ttime_mean);
2363 /* There are other queues in the group, don't do group idle */
2364 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2367 cfq_mark_cfqq_wait_request(cfqq);
2370 sl = cfqd->cfq_group_idle;
2372 sl = cfqd->cfq_slice_idle;
2374 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2375 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2376 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2377 group_idle ? 1 : 0);
2381 * Move request from internal lists to the request queue dispatch list.
2383 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2385 struct cfq_data *cfqd = q->elevator->elevator_data;
2386 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2388 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2390 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2391 cfq_remove_request(rq);
2393 (RQ_CFQG(rq))->dispatched++;
2394 elv_dispatch_sort(q, rq);
2396 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2397 cfqq->nr_sectors += blk_rq_sectors(rq);
2398 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2402 * return expired entry, or NULL to just start from scratch in rbtree
2404 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2406 struct request *rq = NULL;
2408 if (cfq_cfqq_fifo_expire(cfqq))
2411 cfq_mark_cfqq_fifo_expire(cfqq);
2413 if (list_empty(&cfqq->fifo))
2416 rq = rq_entry_fifo(cfqq->fifo.next);
2417 if (time_before(jiffies, rq_fifo_time(rq)))
2420 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2425 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2427 const int base_rq = cfqd->cfq_slice_async_rq;
2429 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2431 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2435 * Must be called with the queue_lock held.
2437 static int cfqq_process_refs(struct cfq_queue *cfqq)
2439 int process_refs, io_refs;
2441 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2442 process_refs = cfqq->ref - io_refs;
2443 BUG_ON(process_refs < 0);
2444 return process_refs;
2447 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2449 int process_refs, new_process_refs;
2450 struct cfq_queue *__cfqq;
2453 * If there are no process references on the new_cfqq, then it is
2454 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2455 * chain may have dropped their last reference (not just their
2456 * last process reference).
2458 if (!cfqq_process_refs(new_cfqq))
2461 /* Avoid a circular list and skip interim queue merges */
2462 while ((__cfqq = new_cfqq->new_cfqq)) {
2468 process_refs = cfqq_process_refs(cfqq);
2469 new_process_refs = cfqq_process_refs(new_cfqq);
2471 * If the process for the cfqq has gone away, there is no
2472 * sense in merging the queues.
2474 if (process_refs == 0 || new_process_refs == 0)
2478 * Merge in the direction of the lesser amount of work.
2480 if (new_process_refs >= process_refs) {
2481 cfqq->new_cfqq = new_cfqq;
2482 new_cfqq->ref += process_refs;
2484 new_cfqq->new_cfqq = cfqq;
2485 cfqq->ref += new_process_refs;
2489 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2490 struct cfq_group *cfqg, enum wl_class_t wl_class)
2492 struct cfq_queue *queue;
2494 bool key_valid = false;
2495 unsigned long lowest_key = 0;
2496 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2498 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2499 /* select the one with lowest rb_key */
2500 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
2502 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2503 lowest_key = queue->rb_key;
2513 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
2517 struct cfq_rb_root *st;
2518 unsigned group_slice;
2519 enum wl_class_t original_class = cfqd->serving_wl_class;
2521 /* Choose next priority. RT > BE > IDLE */
2522 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2523 cfqd->serving_wl_class = RT_WORKLOAD;
2524 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2525 cfqd->serving_wl_class = BE_WORKLOAD;
2527 cfqd->serving_wl_class = IDLE_WORKLOAD;
2528 cfqd->workload_expires = jiffies + 1;
2532 if (original_class != cfqd->serving_wl_class)
2536 * For RT and BE, we have to choose also the type
2537 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2540 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2544 * check workload expiration, and that we still have other queues ready
2546 if (count && !time_after(jiffies, cfqd->workload_expires))
2550 /* otherwise select new workload type */
2551 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
2552 cfqd->serving_wl_class);
2553 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
2557 * the workload slice is computed as a fraction of target latency
2558 * proportional to the number of queues in that workload, over
2559 * all the queues in the same priority class
2561 group_slice = cfq_group_slice(cfqd, cfqg);
2563 slice = group_slice * count /
2564 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
2565 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
2568 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
2572 * Async queues are currently system wide. Just taking
2573 * proportion of queues with-in same group will lead to higher
2574 * async ratio system wide as generally root group is going
2575 * to have higher weight. A more accurate thing would be to
2576 * calculate system wide asnc/sync ratio.
2578 tmp = cfqd->cfq_target_latency *
2579 cfqg_busy_async_queues(cfqd, cfqg);
2580 tmp = tmp/cfqd->busy_queues;
2581 slice = min_t(unsigned, slice, tmp);
2583 /* async workload slice is scaled down according to
2584 * the sync/async slice ratio. */
2585 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2587 /* sync workload slice is at least 2 * cfq_slice_idle */
2588 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2590 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2591 cfq_log(cfqd, "workload slice:%d", slice);
2592 cfqd->workload_expires = jiffies + slice;
2595 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2597 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2598 struct cfq_group *cfqg;
2600 if (RB_EMPTY_ROOT(&st->rb))
2602 cfqg = cfq_rb_first_group(st);
2603 update_min_vdisktime(st);
2607 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2609 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2611 cfqd->serving_group = cfqg;
2613 /* Restore the workload type data */
2614 if (cfqg->saved_wl_slice) {
2615 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
2616 cfqd->serving_wl_type = cfqg->saved_wl_type;
2617 cfqd->serving_wl_class = cfqg->saved_wl_class;
2619 cfqd->workload_expires = jiffies - 1;
2621 choose_wl_class_and_type(cfqd, cfqg);
2625 * Select a queue for service. If we have a current active queue,
2626 * check whether to continue servicing it, or retrieve and set a new one.
2628 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2630 struct cfq_queue *cfqq, *new_cfqq = NULL;
2632 cfqq = cfqd->active_queue;
2636 if (!cfqd->rq_queued)
2640 * We were waiting for group to get backlogged. Expire the queue
2642 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2646 * The active queue has run out of time, expire it and select new.
2648 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2650 * If slice had not expired at the completion of last request
2651 * we might not have turned on wait_busy flag. Don't expire
2652 * the queue yet. Allow the group to get backlogged.
2654 * The very fact that we have used the slice, that means we
2655 * have been idling all along on this queue and it should be
2656 * ok to wait for this request to complete.
2658 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2659 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2663 goto check_group_idle;
2667 * The active queue has requests and isn't expired, allow it to
2670 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2674 * If another queue has a request waiting within our mean seek
2675 * distance, let it run. The expire code will check for close
2676 * cooperators and put the close queue at the front of the service
2677 * tree. If possible, merge the expiring queue with the new cfqq.
2679 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2681 if (!cfqq->new_cfqq)
2682 cfq_setup_merge(cfqq, new_cfqq);
2687 * No requests pending. If the active queue still has requests in
2688 * flight or is idling for a new request, allow either of these
2689 * conditions to happen (or time out) before selecting a new queue.
2691 if (timer_pending(&cfqd->idle_slice_timer)) {
2697 * This is a deep seek queue, but the device is much faster than
2698 * the queue can deliver, don't idle
2700 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2701 (cfq_cfqq_slice_new(cfqq) ||
2702 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2703 cfq_clear_cfqq_deep(cfqq);
2704 cfq_clear_cfqq_idle_window(cfqq);
2707 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2713 * If group idle is enabled and there are requests dispatched from
2714 * this group, wait for requests to complete.
2717 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2718 cfqq->cfqg->dispatched &&
2719 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2725 cfq_slice_expired(cfqd, 0);
2728 * Current queue expired. Check if we have to switch to a new
2732 cfq_choose_cfqg(cfqd);
2734 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2739 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2743 while (cfqq->next_rq) {
2744 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2748 BUG_ON(!list_empty(&cfqq->fifo));
2750 /* By default cfqq is not expired if it is empty. Do it explicitly */
2751 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2756 * Drain our current requests. Used for barriers and when switching
2757 * io schedulers on-the-fly.
2759 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2761 struct cfq_queue *cfqq;
2764 /* Expire the timeslice of the current active queue first */
2765 cfq_slice_expired(cfqd, 0);
2766 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2767 __cfq_set_active_queue(cfqd, cfqq);
2768 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2771 BUG_ON(cfqd->busy_queues);
2773 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2777 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2778 struct cfq_queue *cfqq)
2780 /* the queue hasn't finished any request, can't estimate */
2781 if (cfq_cfqq_slice_new(cfqq))
2783 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2790 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2792 unsigned int max_dispatch;
2795 * Drain async requests before we start sync IO
2797 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2801 * If this is an async queue and we have sync IO in flight, let it wait
2803 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2806 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2807 if (cfq_class_idle(cfqq))
2811 * Does this cfqq already have too much IO in flight?
2813 if (cfqq->dispatched >= max_dispatch) {
2814 bool promote_sync = false;
2816 * idle queue must always only have a single IO in flight
2818 if (cfq_class_idle(cfqq))
2822 * If there is only one sync queue
2823 * we can ignore async queue here and give the sync
2824 * queue no dispatch limit. The reason is a sync queue can
2825 * preempt async queue, limiting the sync queue doesn't make
2826 * sense. This is useful for aiostress test.
2828 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2829 promote_sync = true;
2832 * We have other queues, don't allow more IO from this one
2834 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2839 * Sole queue user, no limit
2841 if (cfqd->busy_queues == 1 || promote_sync)
2845 * Normally we start throttling cfqq when cfq_quantum/2
2846 * requests have been dispatched. But we can drive
2847 * deeper queue depths at the beginning of slice
2848 * subjected to upper limit of cfq_quantum.
2850 max_dispatch = cfqd->cfq_quantum;
2854 * Async queues must wait a bit before being allowed dispatch.
2855 * We also ramp up the dispatch depth gradually for async IO,
2856 * based on the last sync IO we serviced
2858 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2859 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2862 depth = last_sync / cfqd->cfq_slice[1];
2863 if (!depth && !cfqq->dispatched)
2865 if (depth < max_dispatch)
2866 max_dispatch = depth;
2870 * If we're below the current max, allow a dispatch
2872 return cfqq->dispatched < max_dispatch;
2876 * Dispatch a request from cfqq, moving them to the request queue
2879 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2883 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2885 if (!cfq_may_dispatch(cfqd, cfqq))
2889 * follow expired path, else get first next available
2891 rq = cfq_check_fifo(cfqq);
2896 * insert request into driver dispatch list
2898 cfq_dispatch_insert(cfqd->queue, rq);
2900 if (!cfqd->active_cic) {
2901 struct cfq_io_cq *cic = RQ_CIC(rq);
2903 atomic_long_inc(&cic->icq.ioc->refcount);
2904 cfqd->active_cic = cic;
2911 * Find the cfqq that we need to service and move a request from that to the
2914 static int cfq_dispatch_requests(struct request_queue *q, int force)
2916 struct cfq_data *cfqd = q->elevator->elevator_data;
2917 struct cfq_queue *cfqq;
2919 if (!cfqd->busy_queues)
2922 if (unlikely(force))
2923 return cfq_forced_dispatch(cfqd);
2925 cfqq = cfq_select_queue(cfqd);
2930 * Dispatch a request from this cfqq, if it is allowed
2932 if (!cfq_dispatch_request(cfqd, cfqq))
2935 cfqq->slice_dispatch++;
2936 cfq_clear_cfqq_must_dispatch(cfqq);
2939 * expire an async queue immediately if it has used up its slice. idle
2940 * queue always expire after 1 dispatch round.
2942 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2943 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2944 cfq_class_idle(cfqq))) {
2945 cfqq->slice_end = jiffies + 1;
2946 cfq_slice_expired(cfqd, 0);
2949 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2954 * task holds one reference to the queue, dropped when task exits. each rq
2955 * in-flight on this queue also holds a reference, dropped when rq is freed.
2957 * Each cfq queue took a reference on the parent group. Drop it now.
2958 * queue lock must be held here.
2960 static void cfq_put_queue(struct cfq_queue *cfqq)
2962 struct cfq_data *cfqd = cfqq->cfqd;
2963 struct cfq_group *cfqg;
2965 BUG_ON(cfqq->ref <= 0);
2971 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2972 BUG_ON(rb_first(&cfqq->sort_list));
2973 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2976 if (unlikely(cfqd->active_queue == cfqq)) {
2977 __cfq_slice_expired(cfqd, cfqq, 0);
2978 cfq_schedule_dispatch(cfqd);
2981 BUG_ON(cfq_cfqq_on_rr(cfqq));
2982 kmem_cache_free(cfq_pool, cfqq);
2986 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2988 struct cfq_queue *__cfqq, *next;
2991 * If this queue was scheduled to merge with another queue, be
2992 * sure to drop the reference taken on that queue (and others in
2993 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2995 __cfqq = cfqq->new_cfqq;
2997 if (__cfqq == cfqq) {
2998 WARN(1, "cfqq->new_cfqq loop detected\n");
3001 next = __cfqq->new_cfqq;
3002 cfq_put_queue(__cfqq);
3007 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3009 if (unlikely(cfqq == cfqd->active_queue)) {
3010 __cfq_slice_expired(cfqd, cfqq, 0);
3011 cfq_schedule_dispatch(cfqd);
3014 cfq_put_cooperator(cfqq);
3016 cfq_put_queue(cfqq);
3019 static void cfq_init_icq(struct io_cq *icq)
3021 struct cfq_io_cq *cic = icq_to_cic(icq);
3023 cic->ttime.last_end_request = jiffies;
3026 static void cfq_exit_icq(struct io_cq *icq)
3028 struct cfq_io_cq *cic = icq_to_cic(icq);
3029 struct cfq_data *cfqd = cic_to_cfqd(cic);
3031 if (cic->cfqq[BLK_RW_ASYNC]) {
3032 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3033 cic->cfqq[BLK_RW_ASYNC] = NULL;
3036 if (cic->cfqq[BLK_RW_SYNC]) {
3037 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3038 cic->cfqq[BLK_RW_SYNC] = NULL;
3042 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3044 struct task_struct *tsk = current;
3047 if (!cfq_cfqq_prio_changed(cfqq))
3050 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3051 switch (ioprio_class) {
3053 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3054 case IOPRIO_CLASS_NONE:
3056 * no prio set, inherit CPU scheduling settings
3058 cfqq->ioprio = task_nice_ioprio(tsk);
3059 cfqq->ioprio_class = task_nice_ioclass(tsk);
3061 case IOPRIO_CLASS_RT:
3062 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3063 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3065 case IOPRIO_CLASS_BE:
3066 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3067 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3069 case IOPRIO_CLASS_IDLE:
3070 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3072 cfq_clear_cfqq_idle_window(cfqq);
3077 * keep track of original prio settings in case we have to temporarily
3078 * elevate the priority of this queue
3080 cfqq->org_ioprio = cfqq->ioprio;
3081 cfq_clear_cfqq_prio_changed(cfqq);
3084 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3086 int ioprio = cic->icq.ioc->ioprio;
3087 struct cfq_data *cfqd = cic_to_cfqd(cic);
3088 struct cfq_queue *cfqq;
3091 * Check whether ioprio has changed. The condition may trigger
3092 * spuriously on a newly created cic but there's no harm.
3094 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3097 cfqq = cic->cfqq[BLK_RW_ASYNC];
3099 struct cfq_queue *new_cfqq;
3100 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3103 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3104 cfq_put_queue(cfqq);
3108 cfqq = cic->cfqq[BLK_RW_SYNC];
3110 cfq_mark_cfqq_prio_changed(cfqq);
3112 cic->ioprio = ioprio;
3115 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3116 pid_t pid, bool is_sync)
3118 RB_CLEAR_NODE(&cfqq->rb_node);
3119 RB_CLEAR_NODE(&cfqq->p_node);
3120 INIT_LIST_HEAD(&cfqq->fifo);
3125 cfq_mark_cfqq_prio_changed(cfqq);
3128 if (!cfq_class_idle(cfqq))
3129 cfq_mark_cfqq_idle_window(cfqq);
3130 cfq_mark_cfqq_sync(cfqq);
3135 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3136 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3138 struct cfq_data *cfqd = cic_to_cfqd(cic);
3139 struct cfq_queue *sync_cfqq;
3143 id = bio_blkcg(bio)->id;
3147 * Check whether blkcg has changed. The condition may trigger
3148 * spuriously on a newly created cic but there's no harm.
3150 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3153 sync_cfqq = cic_to_cfqq(cic, 1);
3156 * Drop reference to sync queue. A new sync queue will be
3157 * assigned in new group upon arrival of a fresh request.
3159 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3160 cic_set_cfqq(cic, NULL, 1);
3161 cfq_put_queue(sync_cfqq);
3167 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3168 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3170 static struct cfq_queue *
3171 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3172 struct bio *bio, gfp_t gfp_mask)
3174 struct blkcg *blkcg;
3175 struct cfq_queue *cfqq, *new_cfqq = NULL;
3176 struct cfq_group *cfqg;
3181 blkcg = bio_blkcg(bio);
3182 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3183 cfqq = cic_to_cfqq(cic, is_sync);
3186 * Always try a new alloc if we fell back to the OOM cfqq
3187 * originally, since it should just be a temporary situation.
3189 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3194 } else if (gfp_mask & __GFP_WAIT) {
3196 spin_unlock_irq(cfqd->queue->queue_lock);
3197 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3198 gfp_mask | __GFP_ZERO,
3200 spin_lock_irq(cfqd->queue->queue_lock);
3204 cfqq = kmem_cache_alloc_node(cfq_pool,
3205 gfp_mask | __GFP_ZERO,
3210 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3211 cfq_init_prio_data(cfqq, cic);
3212 cfq_link_cfqq_cfqg(cfqq, cfqg);
3213 cfq_log_cfqq(cfqd, cfqq, "alloced");
3215 cfqq = &cfqd->oom_cfqq;
3219 kmem_cache_free(cfq_pool, new_cfqq);
3225 static struct cfq_queue **
3226 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3228 switch (ioprio_class) {
3229 case IOPRIO_CLASS_RT:
3230 return &cfqd->async_cfqq[0][ioprio];
3231 case IOPRIO_CLASS_NONE:
3232 ioprio = IOPRIO_NORM;
3234 case IOPRIO_CLASS_BE:
3235 return &cfqd->async_cfqq[1][ioprio];
3236 case IOPRIO_CLASS_IDLE:
3237 return &cfqd->async_idle_cfqq;
3243 static struct cfq_queue *
3244 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3245 struct bio *bio, gfp_t gfp_mask)
3247 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3248 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3249 struct cfq_queue **async_cfqq = NULL;
3250 struct cfq_queue *cfqq = NULL;
3253 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3258 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3261 * pin the queue now that it's allocated, scheduler exit will prune it
3263 if (!is_sync && !(*async_cfqq)) {
3273 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3275 unsigned long elapsed = jiffies - ttime->last_end_request;
3276 elapsed = min(elapsed, 2UL * slice_idle);
3278 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3279 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3280 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3284 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3285 struct cfq_io_cq *cic)
3287 if (cfq_cfqq_sync(cfqq)) {
3288 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3289 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3290 cfqd->cfq_slice_idle);
3292 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3293 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3298 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3302 sector_t n_sec = blk_rq_sectors(rq);
3303 if (cfqq->last_request_pos) {
3304 if (cfqq->last_request_pos < blk_rq_pos(rq))
3305 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3307 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3310 cfqq->seek_history <<= 1;
3311 if (blk_queue_nonrot(cfqd->queue))
3312 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3314 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3318 * Disable idle window if the process thinks too long or seeks so much that
3322 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3323 struct cfq_io_cq *cic)
3325 int old_idle, enable_idle;
3328 * Don't idle for async or idle io prio class
3330 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3333 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3335 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3336 cfq_mark_cfqq_deep(cfqq);
3338 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3340 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3341 !cfqd->cfq_slice_idle ||
3342 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3344 else if (sample_valid(cic->ttime.ttime_samples)) {
3345 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3351 if (old_idle != enable_idle) {
3352 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3354 cfq_mark_cfqq_idle_window(cfqq);
3356 cfq_clear_cfqq_idle_window(cfqq);
3361 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3362 * no or if we aren't sure, a 1 will cause a preempt.
3365 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3368 struct cfq_queue *cfqq;
3370 cfqq = cfqd->active_queue;
3374 if (cfq_class_idle(new_cfqq))
3377 if (cfq_class_idle(cfqq))
3381 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3383 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3387 * if the new request is sync, but the currently running queue is
3388 * not, let the sync request have priority.
3390 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3393 if (new_cfqq->cfqg != cfqq->cfqg)
3396 if (cfq_slice_used(cfqq))
3399 /* Allow preemption only if we are idling on sync-noidle tree */
3400 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3401 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3402 new_cfqq->service_tree->count == 2 &&
3403 RB_EMPTY_ROOT(&cfqq->sort_list))
3407 * So both queues are sync. Let the new request get disk time if
3408 * it's a metadata request and the current queue is doing regular IO.
3410 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3414 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3416 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3419 /* An idle queue should not be idle now for some reason */
3420 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3423 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3427 * if this request is as-good as one we would expect from the
3428 * current cfqq, let it preempt
3430 if (cfq_rq_close(cfqd, cfqq, rq))
3437 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3438 * let it have half of its nominal slice.
3440 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3442 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3444 cfq_log_cfqq(cfqd, cfqq, "preempt");
3445 cfq_slice_expired(cfqd, 1);
3448 * workload type is changed, don't save slice, otherwise preempt
3451 if (old_type != cfqq_type(cfqq))
3452 cfqq->cfqg->saved_wl_slice = 0;
3455 * Put the new queue at the front of the of the current list,
3456 * so we know that it will be selected next.
3458 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3460 cfq_service_tree_add(cfqd, cfqq, 1);
3462 cfqq->slice_end = 0;
3463 cfq_mark_cfqq_slice_new(cfqq);
3467 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3468 * something we should do about it
3471 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3474 struct cfq_io_cq *cic = RQ_CIC(rq);
3477 if (rq->cmd_flags & REQ_PRIO)
3478 cfqq->prio_pending++;
3480 cfq_update_io_thinktime(cfqd, cfqq, cic);
3481 cfq_update_io_seektime(cfqd, cfqq, rq);
3482 cfq_update_idle_window(cfqd, cfqq, cic);
3484 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3486 if (cfqq == cfqd->active_queue) {
3488 * Remember that we saw a request from this process, but
3489 * don't start queuing just yet. Otherwise we risk seeing lots
3490 * of tiny requests, because we disrupt the normal plugging
3491 * and merging. If the request is already larger than a single
3492 * page, let it rip immediately. For that case we assume that
3493 * merging is already done. Ditto for a busy system that
3494 * has other work pending, don't risk delaying until the
3495 * idle timer unplug to continue working.
3497 if (cfq_cfqq_wait_request(cfqq)) {
3498 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3499 cfqd->busy_queues > 1) {
3500 cfq_del_timer(cfqd, cfqq);
3501 cfq_clear_cfqq_wait_request(cfqq);
3502 __blk_run_queue(cfqd->queue);
3504 cfqg_stats_update_idle_time(cfqq->cfqg);
3505 cfq_mark_cfqq_must_dispatch(cfqq);
3508 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3510 * not the active queue - expire current slice if it is
3511 * idle and has expired it's mean thinktime or this new queue
3512 * has some old slice time left and is of higher priority or
3513 * this new queue is RT and the current one is BE
3515 cfq_preempt_queue(cfqd, cfqq);
3516 __blk_run_queue(cfqd->queue);
3520 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3522 struct cfq_data *cfqd = q->elevator->elevator_data;
3523 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3525 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3526 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3528 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3529 list_add_tail(&rq->queuelist, &cfqq->fifo);
3531 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3533 cfq_rq_enqueued(cfqd, cfqq, rq);
3537 * Update hw_tag based on peak queue depth over 50 samples under
3540 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3542 struct cfq_queue *cfqq = cfqd->active_queue;
3544 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3545 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3547 if (cfqd->hw_tag == 1)
3550 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3551 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3555 * If active queue hasn't enough requests and can idle, cfq might not
3556 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3559 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3560 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3561 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3564 if (cfqd->hw_tag_samples++ < 50)
3567 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3573 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3575 struct cfq_io_cq *cic = cfqd->active_cic;
3577 /* If the queue already has requests, don't wait */
3578 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3581 /* If there are other queues in the group, don't wait */
3582 if (cfqq->cfqg->nr_cfqq > 1)
3585 /* the only queue in the group, but think time is big */
3586 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3589 if (cfq_slice_used(cfqq))
3592 /* if slice left is less than think time, wait busy */
3593 if (cic && sample_valid(cic->ttime.ttime_samples)
3594 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3598 * If think times is less than a jiffy than ttime_mean=0 and above
3599 * will not be true. It might happen that slice has not expired yet
3600 * but will expire soon (4-5 ns) during select_queue(). To cover the
3601 * case where think time is less than a jiffy, mark the queue wait
3602 * busy if only 1 jiffy is left in the slice.
3604 if (cfqq->slice_end - jiffies == 1)
3610 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3612 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3613 struct cfq_data *cfqd = cfqq->cfqd;
3614 const int sync = rq_is_sync(rq);
3618 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3619 !!(rq->cmd_flags & REQ_NOIDLE));
3621 cfq_update_hw_tag(cfqd);
3623 WARN_ON(!cfqd->rq_in_driver);
3624 WARN_ON(!cfqq->dispatched);
3625 cfqd->rq_in_driver--;
3627 (RQ_CFQG(rq))->dispatched--;
3628 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3629 rq_io_start_time_ns(rq), rq->cmd_flags);
3631 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3634 struct cfq_rb_root *st;
3636 RQ_CIC(rq)->ttime.last_end_request = now;
3638 if (cfq_cfqq_on_rr(cfqq))
3639 st = cfqq->service_tree;
3641 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
3644 st->ttime.last_end_request = now;
3645 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3646 cfqd->last_delayed_sync = now;
3649 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3650 cfqq->cfqg->ttime.last_end_request = now;
3654 * If this is the active queue, check if it needs to be expired,
3655 * or if we want to idle in case it has no pending requests.
3657 if (cfqd->active_queue == cfqq) {
3658 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3660 if (cfq_cfqq_slice_new(cfqq)) {
3661 cfq_set_prio_slice(cfqd, cfqq);
3662 cfq_clear_cfqq_slice_new(cfqq);
3666 * Should we wait for next request to come in before we expire
3669 if (cfq_should_wait_busy(cfqd, cfqq)) {
3670 unsigned long extend_sl = cfqd->cfq_slice_idle;
3671 if (!cfqd->cfq_slice_idle)
3672 extend_sl = cfqd->cfq_group_idle;
3673 cfqq->slice_end = jiffies + extend_sl;
3674 cfq_mark_cfqq_wait_busy(cfqq);
3675 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3679 * Idling is not enabled on:
3681 * - idle-priority queues
3683 * - queues with still some requests queued
3684 * - when there is a close cooperator
3686 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3687 cfq_slice_expired(cfqd, 1);
3688 else if (sync && cfqq_empty &&
3689 !cfq_close_cooperator(cfqd, cfqq)) {
3690 cfq_arm_slice_timer(cfqd);
3694 if (!cfqd->rq_in_driver)
3695 cfq_schedule_dispatch(cfqd);
3698 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3700 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3701 cfq_mark_cfqq_must_alloc_slice(cfqq);
3702 return ELV_MQUEUE_MUST;
3705 return ELV_MQUEUE_MAY;
3708 static int cfq_may_queue(struct request_queue *q, int rw)
3710 struct cfq_data *cfqd = q->elevator->elevator_data;
3711 struct task_struct *tsk = current;
3712 struct cfq_io_cq *cic;
3713 struct cfq_queue *cfqq;
3716 * don't force setup of a queue from here, as a call to may_queue
3717 * does not necessarily imply that a request actually will be queued.
3718 * so just lookup a possibly existing queue, or return 'may queue'
3721 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3723 return ELV_MQUEUE_MAY;
3725 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3727 cfq_init_prio_data(cfqq, cic);
3729 return __cfq_may_queue(cfqq);
3732 return ELV_MQUEUE_MAY;
3736 * queue lock held here
3738 static void cfq_put_request(struct request *rq)
3740 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3743 const int rw = rq_data_dir(rq);
3745 BUG_ON(!cfqq->allocated[rw]);
3746 cfqq->allocated[rw]--;
3748 /* Put down rq reference on cfqg */
3749 cfqg_put(RQ_CFQG(rq));
3750 rq->elv.priv[0] = NULL;
3751 rq->elv.priv[1] = NULL;
3753 cfq_put_queue(cfqq);
3757 static struct cfq_queue *
3758 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3759 struct cfq_queue *cfqq)
3761 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3762 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3763 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3764 cfq_put_queue(cfqq);
3765 return cic_to_cfqq(cic, 1);
3769 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3770 * was the last process referring to said cfqq.
3772 static struct cfq_queue *
3773 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3775 if (cfqq_process_refs(cfqq) == 1) {
3776 cfqq->pid = current->pid;
3777 cfq_clear_cfqq_coop(cfqq);
3778 cfq_clear_cfqq_split_coop(cfqq);
3782 cic_set_cfqq(cic, NULL, 1);
3784 cfq_put_cooperator(cfqq);
3786 cfq_put_queue(cfqq);
3790 * Allocate cfq data structures associated with this request.
3793 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3796 struct cfq_data *cfqd = q->elevator->elevator_data;
3797 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3798 const int rw = rq_data_dir(rq);
3799 const bool is_sync = rq_is_sync(rq);
3800 struct cfq_queue *cfqq;
3802 might_sleep_if(gfp_mask & __GFP_WAIT);
3804 spin_lock_irq(q->queue_lock);
3806 check_ioprio_changed(cic, bio);
3807 check_blkcg_changed(cic, bio);
3809 cfqq = cic_to_cfqq(cic, is_sync);
3810 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3811 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3812 cic_set_cfqq(cic, cfqq, is_sync);
3815 * If the queue was seeky for too long, break it apart.
3817 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3818 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3819 cfqq = split_cfqq(cic, cfqq);
3825 * Check to see if this queue is scheduled to merge with
3826 * another, closely cooperating queue. The merging of
3827 * queues happens here as it must be done in process context.
3828 * The reference on new_cfqq was taken in merge_cfqqs.
3831 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3834 cfqq->allocated[rw]++;
3837 cfqg_get(cfqq->cfqg);
3838 rq->elv.priv[0] = cfqq;
3839 rq->elv.priv[1] = cfqq->cfqg;
3840 spin_unlock_irq(q->queue_lock);
3844 static void cfq_kick_queue(struct work_struct *work)
3846 struct cfq_data *cfqd =
3847 container_of(work, struct cfq_data, unplug_work);
3848 struct request_queue *q = cfqd->queue;
3850 spin_lock_irq(q->queue_lock);
3851 __blk_run_queue(cfqd->queue);
3852 spin_unlock_irq(q->queue_lock);
3856 * Timer running if the active_queue is currently idling inside its time slice
3858 static void cfq_idle_slice_timer(unsigned long data)
3860 struct cfq_data *cfqd = (struct cfq_data *) data;
3861 struct cfq_queue *cfqq;
3862 unsigned long flags;
3865 cfq_log(cfqd, "idle timer fired");
3867 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3869 cfqq = cfqd->active_queue;
3874 * We saw a request before the queue expired, let it through
3876 if (cfq_cfqq_must_dispatch(cfqq))
3882 if (cfq_slice_used(cfqq))
3886 * only expire and reinvoke request handler, if there are
3887 * other queues with pending requests
3889 if (!cfqd->busy_queues)
3893 * not expired and it has a request pending, let it dispatch
3895 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3899 * Queue depth flag is reset only when the idle didn't succeed
3901 cfq_clear_cfqq_deep(cfqq);
3904 cfq_slice_expired(cfqd, timed_out);
3906 cfq_schedule_dispatch(cfqd);
3908 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3911 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3913 del_timer_sync(&cfqd->idle_slice_timer);
3914 cancel_work_sync(&cfqd->unplug_work);
3917 static void cfq_put_async_queues(struct cfq_data *cfqd)
3921 for (i = 0; i < IOPRIO_BE_NR; i++) {
3922 if (cfqd->async_cfqq[0][i])
3923 cfq_put_queue(cfqd->async_cfqq[0][i]);
3924 if (cfqd->async_cfqq[1][i])
3925 cfq_put_queue(cfqd->async_cfqq[1][i]);
3928 if (cfqd->async_idle_cfqq)
3929 cfq_put_queue(cfqd->async_idle_cfqq);
3932 static void cfq_exit_queue(struct elevator_queue *e)
3934 struct cfq_data *cfqd = e->elevator_data;
3935 struct request_queue *q = cfqd->queue;
3937 cfq_shutdown_timer_wq(cfqd);
3939 spin_lock_irq(q->queue_lock);
3941 if (cfqd->active_queue)
3942 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3944 cfq_put_async_queues(cfqd);
3946 spin_unlock_irq(q->queue_lock);
3948 cfq_shutdown_timer_wq(cfqd);
3950 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3951 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
3953 kfree(cfqd->root_group);
3958 static int cfq_init_queue(struct request_queue *q)
3960 struct cfq_data *cfqd;
3961 struct blkcg_gq *blkg __maybe_unused;
3964 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3969 q->elevator->elevator_data = cfqd;
3971 /* Init root service tree */
3972 cfqd->grp_service_tree = CFQ_RB_ROOT;
3974 /* Init root group and prefer root group over other groups by default */
3975 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3976 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
3980 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
3983 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3984 GFP_KERNEL, cfqd->queue->node);
3985 if (!cfqd->root_group)
3988 cfq_init_cfqg_base(cfqd->root_group);
3990 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3993 * Not strictly needed (since RB_ROOT just clears the node and we
3994 * zeroed cfqd on alloc), but better be safe in case someone decides
3995 * to add magic to the rb code
3997 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3998 cfqd->prio_trees[i] = RB_ROOT;
4001 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4002 * Grab a permanent reference to it, so that the normal code flow
4003 * will not attempt to free it. oom_cfqq is linked to root_group
4004 * but shouldn't hold a reference as it'll never be unlinked. Lose
4005 * the reference from linking right away.
4007 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4008 cfqd->oom_cfqq.ref++;
4010 spin_lock_irq(q->queue_lock);
4011 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4012 cfqg_put(cfqd->root_group);
4013 spin_unlock_irq(q->queue_lock);
4015 init_timer(&cfqd->idle_slice_timer);
4016 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4017 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4019 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4021 cfqd->cfq_quantum = cfq_quantum;
4022 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4023 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4024 cfqd->cfq_back_max = cfq_back_max;
4025 cfqd->cfq_back_penalty = cfq_back_penalty;
4026 cfqd->cfq_slice[0] = cfq_slice_async;
4027 cfqd->cfq_slice[1] = cfq_slice_sync;
4028 cfqd->cfq_target_latency = cfq_target_latency;
4029 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4030 cfqd->cfq_slice_idle = cfq_slice_idle;
4031 cfqd->cfq_group_idle = cfq_group_idle;
4032 cfqd->cfq_latency = 1;
4035 * we optimistically start assuming sync ops weren't delayed in last
4036 * second, in order to have larger depth for async operations.
4038 cfqd->last_delayed_sync = jiffies - HZ;
4047 * sysfs parts below -->
4050 cfq_var_show(unsigned int var, char *page)
4052 return sprintf(page, "%d\n", var);
4056 cfq_var_store(unsigned int *var, const char *page, size_t count)
4058 char *p = (char *) page;
4060 *var = simple_strtoul(p, &p, 10);
4064 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4065 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4067 struct cfq_data *cfqd = e->elevator_data; \
4068 unsigned int __data = __VAR; \
4070 __data = jiffies_to_msecs(__data); \
4071 return cfq_var_show(__data, (page)); \
4073 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4074 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4075 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4076 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4077 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4078 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4079 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4080 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4081 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4082 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4083 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4084 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4085 #undef SHOW_FUNCTION
4087 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4088 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4090 struct cfq_data *cfqd = e->elevator_data; \
4091 unsigned int __data; \
4092 int ret = cfq_var_store(&__data, (page), count); \
4093 if (__data < (MIN)) \
4095 else if (__data > (MAX)) \
4098 *(__PTR) = msecs_to_jiffies(__data); \
4100 *(__PTR) = __data; \
4103 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4104 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4106 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4108 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4109 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4111 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4112 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4113 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4114 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4115 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4117 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4118 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4119 #undef STORE_FUNCTION
4121 #define CFQ_ATTR(name) \
4122 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4124 static struct elv_fs_entry cfq_attrs[] = {
4126 CFQ_ATTR(fifo_expire_sync),
4127 CFQ_ATTR(fifo_expire_async),
4128 CFQ_ATTR(back_seek_max),
4129 CFQ_ATTR(back_seek_penalty),
4130 CFQ_ATTR(slice_sync),
4131 CFQ_ATTR(slice_async),
4132 CFQ_ATTR(slice_async_rq),
4133 CFQ_ATTR(slice_idle),
4134 CFQ_ATTR(group_idle),
4135 CFQ_ATTR(low_latency),
4136 CFQ_ATTR(target_latency),
4140 static struct elevator_type iosched_cfq = {
4142 .elevator_merge_fn = cfq_merge,
4143 .elevator_merged_fn = cfq_merged_request,
4144 .elevator_merge_req_fn = cfq_merged_requests,
4145 .elevator_allow_merge_fn = cfq_allow_merge,
4146 .elevator_bio_merged_fn = cfq_bio_merged,
4147 .elevator_dispatch_fn = cfq_dispatch_requests,
4148 .elevator_add_req_fn = cfq_insert_request,
4149 .elevator_activate_req_fn = cfq_activate_request,
4150 .elevator_deactivate_req_fn = cfq_deactivate_request,
4151 .elevator_completed_req_fn = cfq_completed_request,
4152 .elevator_former_req_fn = elv_rb_former_request,
4153 .elevator_latter_req_fn = elv_rb_latter_request,
4154 .elevator_init_icq_fn = cfq_init_icq,
4155 .elevator_exit_icq_fn = cfq_exit_icq,
4156 .elevator_set_req_fn = cfq_set_request,
4157 .elevator_put_req_fn = cfq_put_request,
4158 .elevator_may_queue_fn = cfq_may_queue,
4159 .elevator_init_fn = cfq_init_queue,
4160 .elevator_exit_fn = cfq_exit_queue,
4162 .icq_size = sizeof(struct cfq_io_cq),
4163 .icq_align = __alignof__(struct cfq_io_cq),
4164 .elevator_attrs = cfq_attrs,
4165 .elevator_name = "cfq",
4166 .elevator_owner = THIS_MODULE,
4169 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4170 static struct blkcg_policy blkcg_policy_cfq = {
4171 .pd_size = sizeof(struct cfq_group),
4172 .cftypes = cfq_blkcg_files,
4174 .pd_init_fn = cfq_pd_init,
4175 .pd_reset_stats_fn = cfq_pd_reset_stats,
4179 static int __init cfq_init(void)
4184 * could be 0 on HZ < 1000 setups
4186 if (!cfq_slice_async)
4187 cfq_slice_async = 1;
4188 if (!cfq_slice_idle)
4191 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4192 if (!cfq_group_idle)
4195 ret = blkcg_policy_register(&blkcg_policy_cfq);
4203 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4207 ret = elv_register(&iosched_cfq);
4214 kmem_cache_destroy(cfq_pool);
4216 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4217 blkcg_policy_unregister(&blkcg_policy_cfq);
4222 static void __exit cfq_exit(void)
4224 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4225 blkcg_policy_unregister(&blkcg_policy_cfq);
4227 elv_unregister(&iosched_cfq);
4228 kmem_cache_destroy(cfq_pool);
4231 module_init(cfq_init);
4232 module_exit(cfq_exit);
4234 MODULE_AUTHOR("Jens Axboe");
4235 MODULE_LICENSE("GPL");
4236 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");