2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
18 #include "blk-cgroup.h"
20 static struct blkcg_policy blkcg_policy_cfq __maybe_unused;
25 /* max queue in one round of service */
26 static const int cfq_quantum = 8;
27 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
28 /* maximum backwards seek, in KiB */
29 static const int cfq_back_max = 16 * 1024;
30 /* penalty of a backwards seek */
31 static const int cfq_back_penalty = 2;
32 static const int cfq_slice_sync = HZ / 10;
33 static int cfq_slice_async = HZ / 25;
34 static const int cfq_slice_async_rq = 2;
35 static int cfq_slice_idle = HZ / 125;
36 static int cfq_group_idle = HZ / 125;
37 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
38 static const int cfq_hist_divisor = 4;
41 * offset from end of service tree
43 #define CFQ_IDLE_DELAY (HZ / 5)
46 * below this threshold, we consider thinktime immediate
48 #define CFQ_MIN_TT (2)
50 #define CFQ_SLICE_SCALE (5)
51 #define CFQ_HW_QUEUE_MIN (5)
52 #define CFQ_SERVICE_SHIFT 12
54 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
55 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
56 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
57 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
59 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
60 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
61 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
63 static struct kmem_cache *cfq_pool;
65 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
66 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
67 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69 #define sample_valid(samples) ((samples) > 80)
70 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73 unsigned long last_end_request;
75 unsigned long ttime_total;
76 unsigned long ttime_samples;
77 unsigned long ttime_mean;
81 * Most of our rbtree usage is for sorting with min extraction, so
82 * if we cache the leftmost node we don't have to walk down the tree
83 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
84 * move this into the elevator for the rq sorting as well.
90 unsigned total_weight;
92 struct cfq_ttime ttime;
94 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
95 .ttime = {.last_end_request = jiffies,},}
98 * Per process-grouping structure
101 /* reference count */
103 /* various state flags, see below */
105 /* parent cfq_data */
106 struct cfq_data *cfqd;
107 /* service_tree member */
108 struct rb_node rb_node;
109 /* service_tree key */
110 unsigned long rb_key;
111 /* prio tree member */
112 struct rb_node p_node;
113 /* prio tree root we belong to, if any */
114 struct rb_root *p_root;
115 /* sorted list of pending requests */
116 struct rb_root sort_list;
117 /* if fifo isn't expired, next request to serve */
118 struct request *next_rq;
119 /* requests queued in sort_list */
121 /* currently allocated requests */
123 /* fifo list of requests in sort_list */
124 struct list_head fifo;
126 /* time when queue got scheduled in to dispatch first request. */
127 unsigned long dispatch_start;
128 unsigned int allocated_slice;
129 unsigned int slice_dispatch;
130 /* time when first request from queue completed and slice started. */
131 unsigned long slice_start;
132 unsigned long slice_end;
135 /* pending priority requests */
137 /* number of requests that are on the dispatch list or inside driver */
140 /* io prio of this group */
141 unsigned short ioprio, org_ioprio;
142 unsigned short ioprio_class;
147 sector_t last_request_pos;
149 struct cfq_rb_root *service_tree;
150 struct cfq_queue *new_cfqq;
151 struct cfq_group *cfqg;
152 /* Number of sectors dispatched from queue in single dispatch round */
153 unsigned long nr_sectors;
157 * First index in the service_trees.
158 * IDLE is handled separately, so it has negative index
168 * Second index in the service_trees.
172 SYNC_NOIDLE_WORKLOAD = 1,
177 #ifdef CONFIG_CFQ_GROUP_IOSCHED
178 /* total bytes transferred */
179 struct blkg_rwstat service_bytes;
180 /* total IOs serviced, post merge */
181 struct blkg_rwstat serviced;
182 /* number of ios merged */
183 struct blkg_rwstat merged;
184 /* total time spent on device in ns, may not be accurate w/ queueing */
185 struct blkg_rwstat service_time;
186 /* total time spent waiting in scheduler queue in ns */
187 struct blkg_rwstat wait_time;
188 /* number of IOs queued up */
189 struct blkg_rwstat queued;
190 /* total sectors transferred */
191 struct blkg_stat sectors;
192 /* total disk time and nr sectors dispatched by this group */
193 struct blkg_stat time;
194 #ifdef CONFIG_DEBUG_BLK_CGROUP
195 /* time not charged to this cgroup */
196 struct blkg_stat unaccounted_time;
197 /* sum of number of ios queued across all samples */
198 struct blkg_stat avg_queue_size_sum;
199 /* count of samples taken for average */
200 struct blkg_stat avg_queue_size_samples;
201 /* how many times this group has been removed from service tree */
202 struct blkg_stat dequeue;
203 /* total time spent waiting for it to be assigned a timeslice. */
204 struct blkg_stat group_wait_time;
205 /* time spent idling for this blkcg_gq */
206 struct blkg_stat idle_time;
207 /* total time with empty current active q with other requests queued */
208 struct blkg_stat empty_time;
209 /* fields after this shouldn't be cleared on stat reset */
210 uint64_t start_group_wait_time;
211 uint64_t start_idle_time;
212 uint64_t start_empty_time;
214 #endif /* CONFIG_DEBUG_BLK_CGROUP */
215 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
218 /* This is per cgroup per device grouping structure */
220 /* must be the first member */
221 struct blkg_policy_data pd;
223 /* group service_tree member */
224 struct rb_node rb_node;
226 /* group service_tree key */
229 unsigned int new_weight;
230 unsigned int dev_weight;
232 /* number of cfqq currently on this group */
236 * Per group busy queues average. Useful for workload slice calc. We
237 * create the array for each prio class but at run time it is used
238 * only for RT and BE class and slot for IDLE class remains unused.
239 * This is primarily done to avoid confusion and a gcc warning.
241 unsigned int busy_queues_avg[CFQ_PRIO_NR];
243 * rr lists of queues with requests. We maintain service trees for
244 * RT and BE classes. These trees are subdivided in subclasses
245 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
246 * class there is no subclassification and all the cfq queues go on
247 * a single tree service_tree_idle.
248 * Counts are embedded in the cfq_rb_root
250 struct cfq_rb_root service_trees[2][3];
251 struct cfq_rb_root service_tree_idle;
253 unsigned long saved_workload_slice;
254 enum wl_type_t saved_workload;
255 enum wl_prio_t saved_serving_prio;
257 /* number of requests that are on the dispatch list or inside driver */
259 struct cfq_ttime ttime;
260 struct cfqg_stats stats;
264 struct io_cq icq; /* must be the first member */
265 struct cfq_queue *cfqq[2];
266 struct cfq_ttime ttime;
267 int ioprio; /* the current ioprio */
268 #ifdef CONFIG_CFQ_GROUP_IOSCHED
269 uint64_t blkcg_id; /* the current blkcg ID */
274 * Per block device queue structure
277 struct request_queue *queue;
278 /* Root service tree for cfq_groups */
279 struct cfq_rb_root grp_service_tree;
280 struct cfq_group *root_group;
283 * The priority currently being served
285 enum wl_prio_t serving_prio;
286 enum wl_type_t serving_type;
287 unsigned long workload_expires;
288 struct cfq_group *serving_group;
291 * Each priority tree is sorted by next_request position. These
292 * trees are used when determining if two or more queues are
293 * interleaving requests (see cfq_close_cooperator).
295 struct rb_root prio_trees[CFQ_PRIO_LISTS];
297 unsigned int busy_queues;
298 unsigned int busy_sync_queues;
304 * queue-depth detection
310 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
311 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
314 int hw_tag_est_depth;
315 unsigned int hw_tag_samples;
318 * idle window management
320 struct timer_list idle_slice_timer;
321 struct work_struct unplug_work;
323 struct cfq_queue *active_queue;
324 struct cfq_io_cq *active_cic;
327 * async queue for each priority case
329 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
330 struct cfq_queue *async_idle_cfqq;
332 sector_t last_position;
335 * tunables, see top of file
337 unsigned int cfq_quantum;
338 unsigned int cfq_fifo_expire[2];
339 unsigned int cfq_back_penalty;
340 unsigned int cfq_back_max;
341 unsigned int cfq_slice[2];
342 unsigned int cfq_slice_async_rq;
343 unsigned int cfq_slice_idle;
344 unsigned int cfq_group_idle;
345 unsigned int cfq_latency;
348 * Fallback dummy cfqq for extreme OOM conditions
350 struct cfq_queue oom_cfqq;
352 unsigned long last_delayed_sync;
355 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
357 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
364 if (prio == IDLE_WORKLOAD)
365 return &cfqg->service_tree_idle;
367 return &cfqg->service_trees[prio][type];
370 enum cfqq_state_flags {
371 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
372 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
373 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
374 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
375 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
376 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
377 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
378 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
379 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
380 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
381 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
382 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
383 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
386 #define CFQ_CFQQ_FNS(name) \
387 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
389 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
391 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
393 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
395 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
397 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
401 CFQ_CFQQ_FNS(wait_request);
402 CFQ_CFQQ_FNS(must_dispatch);
403 CFQ_CFQQ_FNS(must_alloc_slice);
404 CFQ_CFQQ_FNS(fifo_expire);
405 CFQ_CFQQ_FNS(idle_window);
406 CFQ_CFQQ_FNS(prio_changed);
407 CFQ_CFQQ_FNS(slice_new);
410 CFQ_CFQQ_FNS(split_coop);
412 CFQ_CFQQ_FNS(wait_busy);
415 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
417 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
420 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
422 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
425 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
427 return pd_to_blkg(&cfqg->pd);
430 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
432 /* cfqg stats flags */
433 enum cfqg_stats_flags {
434 CFQG_stats_waiting = 0,
439 #define CFQG_FLAG_FNS(name) \
440 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
442 stats->flags |= (1 << CFQG_stats_##name); \
444 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
446 stats->flags &= ~(1 << CFQG_stats_##name); \
448 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
450 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
453 CFQG_FLAG_FNS(waiting)
454 CFQG_FLAG_FNS(idling)
458 /* This should be called with the queue_lock held. */
459 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
461 unsigned long long now;
463 if (!cfqg_stats_waiting(stats))
467 if (time_after64(now, stats->start_group_wait_time))
468 blkg_stat_add(&stats->group_wait_time,
469 now - stats->start_group_wait_time);
470 cfqg_stats_clear_waiting(stats);
473 /* This should be called with the queue_lock held. */
474 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
475 struct cfq_group *curr_cfqg)
477 struct cfqg_stats *stats = &cfqg->stats;
479 if (cfqg_stats_waiting(stats))
481 if (cfqg == curr_cfqg)
483 stats->start_group_wait_time = sched_clock();
484 cfqg_stats_mark_waiting(stats);
487 /* This should be called with the queue_lock held. */
488 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
490 unsigned long long now;
492 if (!cfqg_stats_empty(stats))
496 if (time_after64(now, stats->start_empty_time))
497 blkg_stat_add(&stats->empty_time,
498 now - stats->start_empty_time);
499 cfqg_stats_clear_empty(stats);
502 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
504 blkg_stat_add(&cfqg->stats.dequeue, 1);
507 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
509 struct cfqg_stats *stats = &cfqg->stats;
511 if (blkg_rwstat_sum(&stats->queued))
515 * group is already marked empty. This can happen if cfqq got new
516 * request in parent group and moved to this group while being added
517 * to service tree. Just ignore the event and move on.
519 if (cfqg_stats_empty(stats))
522 stats->start_empty_time = sched_clock();
523 cfqg_stats_mark_empty(stats);
526 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
528 struct cfqg_stats *stats = &cfqg->stats;
530 if (cfqg_stats_idling(stats)) {
531 unsigned long long now = sched_clock();
533 if (time_after64(now, stats->start_idle_time))
534 blkg_stat_add(&stats->idle_time,
535 now - stats->start_idle_time);
536 cfqg_stats_clear_idling(stats);
540 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
542 struct cfqg_stats *stats = &cfqg->stats;
544 BUG_ON(cfqg_stats_idling(stats));
546 stats->start_idle_time = sched_clock();
547 cfqg_stats_mark_idling(stats);
550 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
552 struct cfqg_stats *stats = &cfqg->stats;
554 blkg_stat_add(&stats->avg_queue_size_sum,
555 blkg_rwstat_sum(&stats->queued));
556 blkg_stat_add(&stats->avg_queue_size_samples, 1);
557 cfqg_stats_update_group_wait_time(stats);
560 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
562 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
563 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
564 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
565 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
566 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
567 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
568 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
570 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
572 #ifdef CONFIG_CFQ_GROUP_IOSCHED
574 static inline void cfqg_get(struct cfq_group *cfqg)
576 return blkg_get(cfqg_to_blkg(cfqg));
579 static inline void cfqg_put(struct cfq_group *cfqg)
581 return blkg_put(cfqg_to_blkg(cfqg));
584 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
587 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
588 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
589 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
593 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
596 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
597 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
600 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
601 struct cfq_group *curr_cfqg, int rw)
603 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
604 cfqg_stats_end_empty_time(&cfqg->stats);
605 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
608 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
609 unsigned long time, unsigned long unaccounted_time)
611 blkg_stat_add(&cfqg->stats.time, time);
612 #ifdef CONFIG_DEBUG_BLK_CGROUP
613 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
617 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
619 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
622 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
624 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
627 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
628 uint64_t bytes, int rw)
630 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
631 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
632 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
635 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
636 uint64_t start_time, uint64_t io_start_time, int rw)
638 struct cfqg_stats *stats = &cfqg->stats;
639 unsigned long long now = sched_clock();
641 if (time_after64(now, io_start_time))
642 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
643 if (time_after64(io_start_time, start_time))
644 blkg_rwstat_add(&stats->wait_time, rw,
645 io_start_time - start_time);
648 static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
650 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
651 struct cfqg_stats *stats = &cfqg->stats;
653 /* queued stats shouldn't be cleared */
654 blkg_rwstat_reset(&stats->service_bytes);
655 blkg_rwstat_reset(&stats->serviced);
656 blkg_rwstat_reset(&stats->merged);
657 blkg_rwstat_reset(&stats->service_time);
658 blkg_rwstat_reset(&stats->wait_time);
659 blkg_stat_reset(&stats->time);
660 #ifdef CONFIG_DEBUG_BLK_CGROUP
661 blkg_stat_reset(&stats->unaccounted_time);
662 blkg_stat_reset(&stats->avg_queue_size_sum);
663 blkg_stat_reset(&stats->avg_queue_size_samples);
664 blkg_stat_reset(&stats->dequeue);
665 blkg_stat_reset(&stats->group_wait_time);
666 blkg_stat_reset(&stats->idle_time);
667 blkg_stat_reset(&stats->empty_time);
671 #else /* CONFIG_CFQ_GROUP_IOSCHED */
673 static inline void cfqg_get(struct cfq_group *cfqg) { }
674 static inline void cfqg_put(struct cfq_group *cfqg) { }
676 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
677 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
678 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
680 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
681 struct cfq_group *curr_cfqg, int rw) { }
682 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
683 unsigned long time, unsigned long unaccounted_time) { }
684 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
685 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
686 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
687 uint64_t bytes, int rw) { }
688 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
689 uint64_t start_time, uint64_t io_start_time, int rw) { }
691 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
693 #define cfq_log(cfqd, fmt, args...) \
694 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
696 /* Traverses through cfq group service trees */
697 #define for_each_cfqg_st(cfqg, i, j, st) \
698 for (i = 0; i <= IDLE_WORKLOAD; i++) \
699 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
700 : &cfqg->service_tree_idle; \
701 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
702 (i == IDLE_WORKLOAD && j == 0); \
703 j++, st = i < IDLE_WORKLOAD ? \
704 &cfqg->service_trees[i][j]: NULL) \
706 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
707 struct cfq_ttime *ttime, bool group_idle)
710 if (!sample_valid(ttime->ttime_samples))
713 slice = cfqd->cfq_group_idle;
715 slice = cfqd->cfq_slice_idle;
716 return ttime->ttime_mean > slice;
719 static inline bool iops_mode(struct cfq_data *cfqd)
722 * If we are not idling on queues and it is a NCQ drive, parallel
723 * execution of requests is on and measuring time is not possible
724 * in most of the cases until and unless we drive shallower queue
725 * depths and that becomes a performance bottleneck. In such cases
726 * switch to start providing fairness in terms of number of IOs.
728 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
734 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
736 if (cfq_class_idle(cfqq))
737 return IDLE_WORKLOAD;
738 if (cfq_class_rt(cfqq))
744 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
746 if (!cfq_cfqq_sync(cfqq))
747 return ASYNC_WORKLOAD;
748 if (!cfq_cfqq_idle_window(cfqq))
749 return SYNC_NOIDLE_WORKLOAD;
750 return SYNC_WORKLOAD;
753 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
754 struct cfq_data *cfqd,
755 struct cfq_group *cfqg)
757 if (wl == IDLE_WORKLOAD)
758 return cfqg->service_tree_idle.count;
760 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
761 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
762 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
765 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
766 struct cfq_group *cfqg)
768 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
769 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
772 static void cfq_dispatch_insert(struct request_queue *, struct request *);
773 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
774 struct cfq_io_cq *cic, struct bio *bio,
777 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
779 /* cic->icq is the first member, %NULL will convert to %NULL */
780 return container_of(icq, struct cfq_io_cq, icq);
783 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
784 struct io_context *ioc)
787 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
791 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
793 return cic->cfqq[is_sync];
796 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
799 cic->cfqq[is_sync] = cfqq;
802 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
804 return cic->icq.q->elevator->elevator_data;
808 * We regard a request as SYNC, if it's either a read or has the SYNC bit
809 * set (in which case it could also be direct WRITE).
811 static inline bool cfq_bio_sync(struct bio *bio)
813 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
817 * scheduler run of queue, if there are requests pending and no one in the
818 * driver that will restart queueing
820 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
822 if (cfqd->busy_queues) {
823 cfq_log(cfqd, "schedule dispatch");
824 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
829 * Scale schedule slice based on io priority. Use the sync time slice only
830 * if a queue is marked sync and has sync io queued. A sync queue with async
831 * io only, should not get full sync slice length.
833 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
836 const int base_slice = cfqd->cfq_slice[sync];
838 WARN_ON(prio >= IOPRIO_BE_NR);
840 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
844 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
846 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
849 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
851 u64 d = delta << CFQ_SERVICE_SHIFT;
853 d = d * CFQ_WEIGHT_DEFAULT;
854 do_div(d, cfqg->weight);
858 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
860 s64 delta = (s64)(vdisktime - min_vdisktime);
862 min_vdisktime = vdisktime;
864 return min_vdisktime;
867 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
869 s64 delta = (s64)(vdisktime - min_vdisktime);
871 min_vdisktime = vdisktime;
873 return min_vdisktime;
876 static void update_min_vdisktime(struct cfq_rb_root *st)
878 struct cfq_group *cfqg;
881 cfqg = rb_entry_cfqg(st->left);
882 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
888 * get averaged number of queues of RT/BE priority.
889 * average is updated, with a formula that gives more weight to higher numbers,
890 * to quickly follows sudden increases and decrease slowly
893 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
894 struct cfq_group *cfqg, bool rt)
896 unsigned min_q, max_q;
897 unsigned mult = cfq_hist_divisor - 1;
898 unsigned round = cfq_hist_divisor / 2;
899 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
901 min_q = min(cfqg->busy_queues_avg[rt], busy);
902 max_q = max(cfqg->busy_queues_avg[rt], busy);
903 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
905 return cfqg->busy_queues_avg[rt];
908 static inline unsigned
909 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
911 struct cfq_rb_root *st = &cfqd->grp_service_tree;
913 return cfq_target_latency * cfqg->weight / st->total_weight;
916 static inline unsigned
917 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
919 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
920 if (cfqd->cfq_latency) {
922 * interested queues (we consider only the ones with the same
923 * priority class in the cfq group)
925 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
927 unsigned sync_slice = cfqd->cfq_slice[1];
928 unsigned expect_latency = sync_slice * iq;
929 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
931 if (expect_latency > group_slice) {
932 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
933 /* scale low_slice according to IO priority
934 * and sync vs async */
936 min(slice, base_low_slice * slice / sync_slice);
937 /* the adapted slice value is scaled to fit all iqs
938 * into the target latency */
939 slice = max(slice * group_slice / expect_latency,
947 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
949 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
951 cfqq->slice_start = jiffies;
952 cfqq->slice_end = jiffies + slice;
953 cfqq->allocated_slice = slice;
954 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
958 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
959 * isn't valid until the first request from the dispatch is activated
960 * and the slice time set.
962 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
964 if (cfq_cfqq_slice_new(cfqq))
966 if (time_before(jiffies, cfqq->slice_end))
973 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
974 * We choose the request that is closest to the head right now. Distance
975 * behind the head is penalized and only allowed to a certain extent.
977 static struct request *
978 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
980 sector_t s1, s2, d1 = 0, d2 = 0;
981 unsigned long back_max;
982 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
983 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
984 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
986 if (rq1 == NULL || rq1 == rq2)
991 if (rq_is_sync(rq1) != rq_is_sync(rq2))
992 return rq_is_sync(rq1) ? rq1 : rq2;
994 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
995 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
997 s1 = blk_rq_pos(rq1);
998 s2 = blk_rq_pos(rq2);
1001 * by definition, 1KiB is 2 sectors
1003 back_max = cfqd->cfq_back_max * 2;
1006 * Strict one way elevator _except_ in the case where we allow
1007 * short backward seeks which are biased as twice the cost of a
1008 * similar forward seek.
1012 else if (s1 + back_max >= last)
1013 d1 = (last - s1) * cfqd->cfq_back_penalty;
1015 wrap |= CFQ_RQ1_WRAP;
1019 else if (s2 + back_max >= last)
1020 d2 = (last - s2) * cfqd->cfq_back_penalty;
1022 wrap |= CFQ_RQ2_WRAP;
1024 /* Found required data */
1027 * By doing switch() on the bit mask "wrap" we avoid having to
1028 * check two variables for all permutations: --> faster!
1031 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1047 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1050 * Since both rqs are wrapped,
1051 * start with the one that's further behind head
1052 * (--> only *one* back seek required),
1053 * since back seek takes more time than forward.
1063 * The below is leftmost cache rbtree addon
1065 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1067 /* Service tree is empty */
1072 root->left = rb_first(&root->rb);
1075 return rb_entry(root->left, struct cfq_queue, rb_node);
1080 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1083 root->left = rb_first(&root->rb);
1086 return rb_entry_cfqg(root->left);
1091 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1097 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1099 if (root->left == n)
1101 rb_erase_init(n, &root->rb);
1106 * would be nice to take fifo expire time into account as well
1108 static struct request *
1109 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1110 struct request *last)
1112 struct rb_node *rbnext = rb_next(&last->rb_node);
1113 struct rb_node *rbprev = rb_prev(&last->rb_node);
1114 struct request *next = NULL, *prev = NULL;
1116 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1119 prev = rb_entry_rq(rbprev);
1122 next = rb_entry_rq(rbnext);
1124 rbnext = rb_first(&cfqq->sort_list);
1125 if (rbnext && rbnext != &last->rb_node)
1126 next = rb_entry_rq(rbnext);
1129 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1132 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1133 struct cfq_queue *cfqq)
1136 * just an approximation, should be ok.
1138 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1139 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1143 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1145 return cfqg->vdisktime - st->min_vdisktime;
1149 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1151 struct rb_node **node = &st->rb.rb_node;
1152 struct rb_node *parent = NULL;
1153 struct cfq_group *__cfqg;
1154 s64 key = cfqg_key(st, cfqg);
1157 while (*node != NULL) {
1159 __cfqg = rb_entry_cfqg(parent);
1161 if (key < cfqg_key(st, __cfqg))
1162 node = &parent->rb_left;
1164 node = &parent->rb_right;
1170 st->left = &cfqg->rb_node;
1172 rb_link_node(&cfqg->rb_node, parent, node);
1173 rb_insert_color(&cfqg->rb_node, &st->rb);
1177 cfq_update_group_weight(struct cfq_group *cfqg)
1179 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1180 if (cfqg->new_weight) {
1181 cfqg->weight = cfqg->new_weight;
1182 cfqg->new_weight = 0;
1187 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1189 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1191 cfq_update_group_weight(cfqg);
1192 __cfq_group_service_tree_add(st, cfqg);
1193 st->total_weight += cfqg->weight;
1197 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1199 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1200 struct cfq_group *__cfqg;
1204 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1208 * Currently put the group at the end. Later implement something
1209 * so that groups get lesser vtime based on their weights, so that
1210 * if group does not loose all if it was not continuously backlogged.
1212 n = rb_last(&st->rb);
1214 __cfqg = rb_entry_cfqg(n);
1215 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1217 cfqg->vdisktime = st->min_vdisktime;
1218 cfq_group_service_tree_add(st, cfqg);
1222 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1224 st->total_weight -= cfqg->weight;
1225 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1226 cfq_rb_erase(&cfqg->rb_node, st);
1230 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1232 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1234 BUG_ON(cfqg->nr_cfqq < 1);
1237 /* If there are other cfq queues under this group, don't delete it */
1241 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1242 cfq_group_service_tree_del(st, cfqg);
1243 cfqg->saved_workload_slice = 0;
1244 cfqg_stats_update_dequeue(cfqg);
1247 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1248 unsigned int *unaccounted_time)
1250 unsigned int slice_used;
1253 * Queue got expired before even a single request completed or
1254 * got expired immediately after first request completion.
1256 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1258 * Also charge the seek time incurred to the group, otherwise
1259 * if there are mutiple queues in the group, each can dispatch
1260 * a single request on seeky media and cause lots of seek time
1261 * and group will never know it.
1263 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1266 slice_used = jiffies - cfqq->slice_start;
1267 if (slice_used > cfqq->allocated_slice) {
1268 *unaccounted_time = slice_used - cfqq->allocated_slice;
1269 slice_used = cfqq->allocated_slice;
1271 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1272 *unaccounted_time += cfqq->slice_start -
1273 cfqq->dispatch_start;
1279 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1280 struct cfq_queue *cfqq)
1282 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1283 unsigned int used_sl, charge, unaccounted_sl = 0;
1284 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1285 - cfqg->service_tree_idle.count;
1287 BUG_ON(nr_sync < 0);
1288 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1290 if (iops_mode(cfqd))
1291 charge = cfqq->slice_dispatch;
1292 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1293 charge = cfqq->allocated_slice;
1295 /* Can't update vdisktime while group is on service tree */
1296 cfq_group_service_tree_del(st, cfqg);
1297 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1298 /* If a new weight was requested, update now, off tree */
1299 cfq_group_service_tree_add(st, cfqg);
1301 /* This group is being expired. Save the context */
1302 if (time_after(cfqd->workload_expires, jiffies)) {
1303 cfqg->saved_workload_slice = cfqd->workload_expires
1305 cfqg->saved_workload = cfqd->serving_type;
1306 cfqg->saved_serving_prio = cfqd->serving_prio;
1308 cfqg->saved_workload_slice = 0;
1310 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1312 cfq_log_cfqq(cfqq->cfqd, cfqq,
1313 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1314 used_sl, cfqq->slice_dispatch, charge,
1315 iops_mode(cfqd), cfqq->nr_sectors);
1316 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1317 cfqg_stats_set_start_empty_time(cfqg);
1321 * cfq_init_cfqg_base - initialize base part of a cfq_group
1322 * @cfqg: cfq_group to initialize
1324 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1325 * is enabled or not.
1327 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1329 struct cfq_rb_root *st;
1332 for_each_cfqg_st(cfqg, i, j, st)
1334 RB_CLEAR_NODE(&cfqg->rb_node);
1336 cfqg->ttime.last_end_request = jiffies;
1339 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1340 static void cfq_pd_init(struct blkcg_gq *blkg)
1342 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1344 cfq_init_cfqg_base(cfqg);
1345 cfqg->weight = blkg->blkcg->cfq_weight;
1349 * Search for the cfq group current task belongs to. request_queue lock must
1352 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1353 struct blkcg *blkcg)
1355 struct request_queue *q = cfqd->queue;
1356 struct cfq_group *cfqg = NULL;
1358 /* avoid lookup for the common case where there's no blkcg */
1359 if (blkcg == &blkcg_root) {
1360 cfqg = cfqd->root_group;
1362 struct blkcg_gq *blkg;
1364 blkg = blkg_lookup_create(blkcg, q);
1366 cfqg = blkg_to_cfqg(blkg);
1372 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1374 /* Currently, all async queues are mapped to root group */
1375 if (!cfq_cfqq_sync(cfqq))
1376 cfqg = cfqq->cfqd->root_group;
1379 /* cfqq reference on cfqg */
1383 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1384 struct blkg_policy_data *pd, int off)
1386 struct cfq_group *cfqg = pd_to_cfqg(pd);
1388 if (!cfqg->dev_weight)
1390 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1393 static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1394 struct seq_file *sf)
1396 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1397 cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
1402 static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1403 struct seq_file *sf)
1405 seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
1409 static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1412 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1413 struct blkg_conf_ctx ctx;
1414 struct cfq_group *cfqg;
1417 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1422 cfqg = blkg_to_cfqg(ctx.blkg);
1423 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1424 cfqg->dev_weight = ctx.v;
1425 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1429 blkg_conf_finish(&ctx);
1433 static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1435 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1436 struct blkcg_gq *blkg;
1437 struct hlist_node *n;
1439 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1442 spin_lock_irq(&blkcg->lock);
1443 blkcg->cfq_weight = (unsigned int)val;
1445 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1446 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1448 if (cfqg && !cfqg->dev_weight)
1449 cfqg->new_weight = blkcg->cfq_weight;
1452 spin_unlock_irq(&blkcg->lock);
1456 static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
1457 struct seq_file *sf)
1459 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1461 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
1462 cft->private, false);
1466 static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
1467 struct seq_file *sf)
1469 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1471 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
1472 cft->private, true);
1476 #ifdef CONFIG_DEBUG_BLK_CGROUP
1477 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1478 struct blkg_policy_data *pd, int off)
1480 struct cfq_group *cfqg = pd_to_cfqg(pd);
1481 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1485 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1488 __blkg_prfill_u64(sf, pd, v);
1492 /* print avg_queue_size */
1493 static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1494 struct seq_file *sf)
1496 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1498 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1499 &blkcg_policy_cfq, 0, false);
1502 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1504 static struct cftype cfq_blkcg_files[] = {
1506 .name = "weight_device",
1507 .read_seq_string = cfqg_print_weight_device,
1508 .write_string = cfqg_set_weight_device,
1509 .max_write_len = 256,
1513 .read_seq_string = cfq_print_weight,
1514 .write_u64 = cfq_set_weight,
1518 .private = offsetof(struct cfq_group, stats.time),
1519 .read_seq_string = cfqg_print_stat,
1523 .private = offsetof(struct cfq_group, stats.sectors),
1524 .read_seq_string = cfqg_print_stat,
1527 .name = "io_service_bytes",
1528 .private = offsetof(struct cfq_group, stats.service_bytes),
1529 .read_seq_string = cfqg_print_rwstat,
1532 .name = "io_serviced",
1533 .private = offsetof(struct cfq_group, stats.serviced),
1534 .read_seq_string = cfqg_print_rwstat,
1537 .name = "io_service_time",
1538 .private = offsetof(struct cfq_group, stats.service_time),
1539 .read_seq_string = cfqg_print_rwstat,
1542 .name = "io_wait_time",
1543 .private = offsetof(struct cfq_group, stats.wait_time),
1544 .read_seq_string = cfqg_print_rwstat,
1547 .name = "io_merged",
1548 .private = offsetof(struct cfq_group, stats.merged),
1549 .read_seq_string = cfqg_print_rwstat,
1552 .name = "io_queued",
1553 .private = offsetof(struct cfq_group, stats.queued),
1554 .read_seq_string = cfqg_print_rwstat,
1556 #ifdef CONFIG_DEBUG_BLK_CGROUP
1558 .name = "avg_queue_size",
1559 .read_seq_string = cfqg_print_avg_queue_size,
1562 .name = "group_wait_time",
1563 .private = offsetof(struct cfq_group, stats.group_wait_time),
1564 .read_seq_string = cfqg_print_stat,
1567 .name = "idle_time",
1568 .private = offsetof(struct cfq_group, stats.idle_time),
1569 .read_seq_string = cfqg_print_stat,
1572 .name = "empty_time",
1573 .private = offsetof(struct cfq_group, stats.empty_time),
1574 .read_seq_string = cfqg_print_stat,
1578 .private = offsetof(struct cfq_group, stats.dequeue),
1579 .read_seq_string = cfqg_print_stat,
1582 .name = "unaccounted_time",
1583 .private = offsetof(struct cfq_group, stats.unaccounted_time),
1584 .read_seq_string = cfqg_print_stat,
1586 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1589 #else /* GROUP_IOSCHED */
1590 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1591 struct blkcg *blkcg)
1593 return cfqd->root_group;
1597 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1601 #endif /* GROUP_IOSCHED */
1604 * The cfqd->service_trees holds all pending cfq_queue's that have
1605 * requests waiting to be processed. It is sorted in the order that
1606 * we will service the queues.
1608 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1611 struct rb_node **p, *parent;
1612 struct cfq_queue *__cfqq;
1613 unsigned long rb_key;
1614 struct cfq_rb_root *service_tree;
1618 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1620 if (cfq_class_idle(cfqq)) {
1621 rb_key = CFQ_IDLE_DELAY;
1622 parent = rb_last(&service_tree->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(service_tree);
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 &&
1650 cfqq->service_tree == service_tree)
1653 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1654 cfqq->service_tree = NULL;
1659 cfqq->service_tree = service_tree;
1660 p = &service_tree->rb.rb_node;
1665 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1668 * sort by key, that represents service time.
1670 if (time_before(rb_key, __cfqq->rb_key))
1673 n = &(*p)->rb_right;
1681 service_tree->left = &cfqq->rb_node;
1683 cfqq->rb_key = rb_key;
1684 rb_link_node(&cfqq->rb_node, parent, p);
1685 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1686 service_tree->count++;
1687 if (add_front || !new_cfqq)
1689 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1692 static struct cfq_queue *
1693 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1694 sector_t sector, struct rb_node **ret_parent,
1695 struct rb_node ***rb_link)
1697 struct rb_node **p, *parent;
1698 struct cfq_queue *cfqq = NULL;
1706 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1709 * Sort strictly based on sector. Smallest to the left,
1710 * largest to the right.
1712 if (sector > blk_rq_pos(cfqq->next_rq))
1713 n = &(*p)->rb_right;
1714 else if (sector < blk_rq_pos(cfqq->next_rq))
1722 *ret_parent = parent;
1728 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1730 struct rb_node **p, *parent;
1731 struct cfq_queue *__cfqq;
1734 rb_erase(&cfqq->p_node, cfqq->p_root);
1735 cfqq->p_root = NULL;
1738 if (cfq_class_idle(cfqq))
1743 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1744 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1745 blk_rq_pos(cfqq->next_rq), &parent, &p);
1747 rb_link_node(&cfqq->p_node, parent, p);
1748 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1750 cfqq->p_root = NULL;
1754 * Update cfqq's position in the service tree.
1756 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1759 * Resorting requires the cfqq to be on the RR list already.
1761 if (cfq_cfqq_on_rr(cfqq)) {
1762 cfq_service_tree_add(cfqd, cfqq, 0);
1763 cfq_prio_tree_add(cfqd, cfqq);
1768 * add to busy list of queues for service, trying to be fair in ordering
1769 * the pending list according to last request service
1771 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1773 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1774 BUG_ON(cfq_cfqq_on_rr(cfqq));
1775 cfq_mark_cfqq_on_rr(cfqq);
1776 cfqd->busy_queues++;
1777 if (cfq_cfqq_sync(cfqq))
1778 cfqd->busy_sync_queues++;
1780 cfq_resort_rr_list(cfqd, cfqq);
1784 * Called when the cfqq no longer has requests pending, remove it from
1787 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1789 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1790 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1791 cfq_clear_cfqq_on_rr(cfqq);
1793 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1794 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1795 cfqq->service_tree = NULL;
1798 rb_erase(&cfqq->p_node, cfqq->p_root);
1799 cfqq->p_root = NULL;
1802 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1803 BUG_ON(!cfqd->busy_queues);
1804 cfqd->busy_queues--;
1805 if (cfq_cfqq_sync(cfqq))
1806 cfqd->busy_sync_queues--;
1810 * rb tree support functions
1812 static void cfq_del_rq_rb(struct request *rq)
1814 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1815 const int sync = rq_is_sync(rq);
1817 BUG_ON(!cfqq->queued[sync]);
1818 cfqq->queued[sync]--;
1820 elv_rb_del(&cfqq->sort_list, rq);
1822 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1824 * Queue will be deleted from service tree when we actually
1825 * expire it later. Right now just remove it from prio tree
1829 rb_erase(&cfqq->p_node, cfqq->p_root);
1830 cfqq->p_root = NULL;
1835 static void cfq_add_rq_rb(struct request *rq)
1837 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1838 struct cfq_data *cfqd = cfqq->cfqd;
1839 struct request *prev;
1841 cfqq->queued[rq_is_sync(rq)]++;
1843 elv_rb_add(&cfqq->sort_list, rq);
1845 if (!cfq_cfqq_on_rr(cfqq))
1846 cfq_add_cfqq_rr(cfqd, cfqq);
1849 * check if this request is a better next-serve candidate
1851 prev = cfqq->next_rq;
1852 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1855 * adjust priority tree position, if ->next_rq changes
1857 if (prev != cfqq->next_rq)
1858 cfq_prio_tree_add(cfqd, cfqq);
1860 BUG_ON(!cfqq->next_rq);
1863 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1865 elv_rb_del(&cfqq->sort_list, rq);
1866 cfqq->queued[rq_is_sync(rq)]--;
1867 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1869 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1873 static struct request *
1874 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1876 struct task_struct *tsk = current;
1877 struct cfq_io_cq *cic;
1878 struct cfq_queue *cfqq;
1880 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1884 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1886 sector_t sector = bio->bi_sector + bio_sectors(bio);
1888 return elv_rb_find(&cfqq->sort_list, sector);
1894 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1896 struct cfq_data *cfqd = q->elevator->elevator_data;
1898 cfqd->rq_in_driver++;
1899 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1900 cfqd->rq_in_driver);
1902 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1905 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1907 struct cfq_data *cfqd = q->elevator->elevator_data;
1909 WARN_ON(!cfqd->rq_in_driver);
1910 cfqd->rq_in_driver--;
1911 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1912 cfqd->rq_in_driver);
1915 static void cfq_remove_request(struct request *rq)
1917 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1919 if (cfqq->next_rq == rq)
1920 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1922 list_del_init(&rq->queuelist);
1925 cfqq->cfqd->rq_queued--;
1926 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1927 if (rq->cmd_flags & REQ_PRIO) {
1928 WARN_ON(!cfqq->prio_pending);
1929 cfqq->prio_pending--;
1933 static int cfq_merge(struct request_queue *q, struct request **req,
1936 struct cfq_data *cfqd = q->elevator->elevator_data;
1937 struct request *__rq;
1939 __rq = cfq_find_rq_fmerge(cfqd, bio);
1940 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1942 return ELEVATOR_FRONT_MERGE;
1945 return ELEVATOR_NO_MERGE;
1948 static void cfq_merged_request(struct request_queue *q, struct request *req,
1951 if (type == ELEVATOR_FRONT_MERGE) {
1952 struct cfq_queue *cfqq = RQ_CFQQ(req);
1954 cfq_reposition_rq_rb(cfqq, req);
1958 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1961 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1965 cfq_merged_requests(struct request_queue *q, struct request *rq,
1966 struct request *next)
1968 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1969 struct cfq_data *cfqd = q->elevator->elevator_data;
1972 * reposition in fifo if next is older than rq
1974 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1975 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1976 list_move(&rq->queuelist, &next->queuelist);
1977 rq_set_fifo_time(rq, rq_fifo_time(next));
1980 if (cfqq->next_rq == next)
1982 cfq_remove_request(next);
1983 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1985 cfqq = RQ_CFQQ(next);
1987 * all requests of this queue are merged to other queues, delete it
1988 * from the service tree. If it's the active_queue,
1989 * cfq_dispatch_requests() will choose to expire it or do idle
1991 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1992 cfqq != cfqd->active_queue)
1993 cfq_del_cfqq_rr(cfqd, cfqq);
1996 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1999 struct cfq_data *cfqd = q->elevator->elevator_data;
2000 struct cfq_io_cq *cic;
2001 struct cfq_queue *cfqq;
2004 * Disallow merge of a sync bio into an async request.
2006 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2010 * Lookup the cfqq that this bio will be queued with and allow
2011 * merge only if rq is queued there.
2013 cic = cfq_cic_lookup(cfqd, current->io_context);
2017 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2018 return cfqq == RQ_CFQQ(rq);
2021 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2023 del_timer(&cfqd->idle_slice_timer);
2024 cfqg_stats_update_idle_time(cfqq->cfqg);
2027 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2028 struct cfq_queue *cfqq)
2031 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
2032 cfqd->serving_prio, cfqd->serving_type);
2033 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2034 cfqq->slice_start = 0;
2035 cfqq->dispatch_start = jiffies;
2036 cfqq->allocated_slice = 0;
2037 cfqq->slice_end = 0;
2038 cfqq->slice_dispatch = 0;
2039 cfqq->nr_sectors = 0;
2041 cfq_clear_cfqq_wait_request(cfqq);
2042 cfq_clear_cfqq_must_dispatch(cfqq);
2043 cfq_clear_cfqq_must_alloc_slice(cfqq);
2044 cfq_clear_cfqq_fifo_expire(cfqq);
2045 cfq_mark_cfqq_slice_new(cfqq);
2047 cfq_del_timer(cfqd, cfqq);
2050 cfqd->active_queue = cfqq;
2054 * current cfqq expired its slice (or was too idle), select new one
2057 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2060 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2062 if (cfq_cfqq_wait_request(cfqq))
2063 cfq_del_timer(cfqd, cfqq);
2065 cfq_clear_cfqq_wait_request(cfqq);
2066 cfq_clear_cfqq_wait_busy(cfqq);
2069 * If this cfqq is shared between multiple processes, check to
2070 * make sure that those processes are still issuing I/Os within
2071 * the mean seek distance. If not, it may be time to break the
2072 * queues apart again.
2074 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2075 cfq_mark_cfqq_split_coop(cfqq);
2078 * store what was left of this slice, if the queue idled/timed out
2081 if (cfq_cfqq_slice_new(cfqq))
2082 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2084 cfqq->slice_resid = cfqq->slice_end - jiffies;
2085 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2088 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2090 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2091 cfq_del_cfqq_rr(cfqd, cfqq);
2093 cfq_resort_rr_list(cfqd, cfqq);
2095 if (cfqq == cfqd->active_queue)
2096 cfqd->active_queue = NULL;
2098 if (cfqd->active_cic) {
2099 put_io_context(cfqd->active_cic->icq.ioc);
2100 cfqd->active_cic = NULL;
2104 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2106 struct cfq_queue *cfqq = cfqd->active_queue;
2109 __cfq_slice_expired(cfqd, cfqq, timed_out);
2113 * Get next queue for service. Unless we have a queue preemption,
2114 * we'll simply select the first cfqq in the service tree.
2116 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2118 struct cfq_rb_root *service_tree =
2119 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
2120 cfqd->serving_type);
2122 if (!cfqd->rq_queued)
2125 /* There is nothing to dispatch */
2128 if (RB_EMPTY_ROOT(&service_tree->rb))
2130 return cfq_rb_first(service_tree);
2133 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2135 struct cfq_group *cfqg;
2136 struct cfq_queue *cfqq;
2138 struct cfq_rb_root *st;
2140 if (!cfqd->rq_queued)
2143 cfqg = cfq_get_next_cfqg(cfqd);
2147 for_each_cfqg_st(cfqg, i, j, st)
2148 if ((cfqq = cfq_rb_first(st)) != NULL)
2154 * Get and set a new active queue for service.
2156 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2157 struct cfq_queue *cfqq)
2160 cfqq = cfq_get_next_queue(cfqd);
2162 __cfq_set_active_queue(cfqd, cfqq);
2166 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2169 if (blk_rq_pos(rq) >= cfqd->last_position)
2170 return blk_rq_pos(rq) - cfqd->last_position;
2172 return cfqd->last_position - blk_rq_pos(rq);
2175 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2178 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2181 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2182 struct cfq_queue *cur_cfqq)
2184 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2185 struct rb_node *parent, *node;
2186 struct cfq_queue *__cfqq;
2187 sector_t sector = cfqd->last_position;
2189 if (RB_EMPTY_ROOT(root))
2193 * First, if we find a request starting at the end of the last
2194 * request, choose it.
2196 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2201 * If the exact sector wasn't found, the parent of the NULL leaf
2202 * will contain the closest sector.
2204 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2205 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2208 if (blk_rq_pos(__cfqq->next_rq) < sector)
2209 node = rb_next(&__cfqq->p_node);
2211 node = rb_prev(&__cfqq->p_node);
2215 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2216 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2224 * cur_cfqq - passed in so that we don't decide that the current queue is
2225 * closely cooperating with itself.
2227 * So, basically we're assuming that that cur_cfqq has dispatched at least
2228 * one request, and that cfqd->last_position reflects a position on the disk
2229 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2232 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2233 struct cfq_queue *cur_cfqq)
2235 struct cfq_queue *cfqq;
2237 if (cfq_class_idle(cur_cfqq))
2239 if (!cfq_cfqq_sync(cur_cfqq))
2241 if (CFQQ_SEEKY(cur_cfqq))
2245 * Don't search priority tree if it's the only queue in the group.
2247 if (cur_cfqq->cfqg->nr_cfqq == 1)
2251 * We should notice if some of the queues are cooperating, eg
2252 * working closely on the same area of the disk. In that case,
2253 * we can group them together and don't waste time idling.
2255 cfqq = cfqq_close(cfqd, cur_cfqq);
2259 /* If new queue belongs to different cfq_group, don't choose it */
2260 if (cur_cfqq->cfqg != cfqq->cfqg)
2264 * It only makes sense to merge sync queues.
2266 if (!cfq_cfqq_sync(cfqq))
2268 if (CFQQ_SEEKY(cfqq))
2272 * Do not merge queues of different priority classes
2274 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2281 * Determine whether we should enforce idle window for this queue.
2284 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2286 enum wl_prio_t prio = cfqq_prio(cfqq);
2287 struct cfq_rb_root *service_tree = cfqq->service_tree;
2289 BUG_ON(!service_tree);
2290 BUG_ON(!service_tree->count);
2292 if (!cfqd->cfq_slice_idle)
2295 /* We never do for idle class queues. */
2296 if (prio == IDLE_WORKLOAD)
2299 /* We do for queues that were marked with idle window flag. */
2300 if (cfq_cfqq_idle_window(cfqq) &&
2301 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2305 * Otherwise, we do only if they are the last ones
2306 * in their service tree.
2308 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2309 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
2311 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2312 service_tree->count);
2316 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2318 struct cfq_queue *cfqq = cfqd->active_queue;
2319 struct cfq_io_cq *cic;
2320 unsigned long sl, group_idle = 0;
2323 * SSD device without seek penalty, disable idling. But only do so
2324 * for devices that support queuing, otherwise we still have a problem
2325 * with sync vs async workloads.
2327 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2330 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2331 WARN_ON(cfq_cfqq_slice_new(cfqq));
2334 * idle is disabled, either manually or by past process history
2336 if (!cfq_should_idle(cfqd, cfqq)) {
2337 /* no queue idling. Check for group idling */
2338 if (cfqd->cfq_group_idle)
2339 group_idle = cfqd->cfq_group_idle;
2345 * still active requests from this queue, don't idle
2347 if (cfqq->dispatched)
2351 * task has exited, don't wait
2353 cic = cfqd->active_cic;
2354 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2358 * If our average think time is larger than the remaining time
2359 * slice, then don't idle. This avoids overrunning the allotted
2362 if (sample_valid(cic->ttime.ttime_samples) &&
2363 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2364 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2365 cic->ttime.ttime_mean);
2369 /* There are other queues in the group, don't do group idle */
2370 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2373 cfq_mark_cfqq_wait_request(cfqq);
2376 sl = cfqd->cfq_group_idle;
2378 sl = cfqd->cfq_slice_idle;
2380 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2381 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2382 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2383 group_idle ? 1 : 0);
2387 * Move request from internal lists to the request queue dispatch list.
2389 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2391 struct cfq_data *cfqd = q->elevator->elevator_data;
2392 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2394 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2396 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2397 cfq_remove_request(rq);
2399 (RQ_CFQG(rq))->dispatched++;
2400 elv_dispatch_sort(q, rq);
2402 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2403 cfqq->nr_sectors += blk_rq_sectors(rq);
2404 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2408 * return expired entry, or NULL to just start from scratch in rbtree
2410 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2412 struct request *rq = NULL;
2414 if (cfq_cfqq_fifo_expire(cfqq))
2417 cfq_mark_cfqq_fifo_expire(cfqq);
2419 if (list_empty(&cfqq->fifo))
2422 rq = rq_entry_fifo(cfqq->fifo.next);
2423 if (time_before(jiffies, rq_fifo_time(rq)))
2426 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2431 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2433 const int base_rq = cfqd->cfq_slice_async_rq;
2435 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2437 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2441 * Must be called with the queue_lock held.
2443 static int cfqq_process_refs(struct cfq_queue *cfqq)
2445 int process_refs, io_refs;
2447 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2448 process_refs = cfqq->ref - io_refs;
2449 BUG_ON(process_refs < 0);
2450 return process_refs;
2453 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2455 int process_refs, new_process_refs;
2456 struct cfq_queue *__cfqq;
2459 * If there are no process references on the new_cfqq, then it is
2460 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2461 * chain may have dropped their last reference (not just their
2462 * last process reference).
2464 if (!cfqq_process_refs(new_cfqq))
2467 /* Avoid a circular list and skip interim queue merges */
2468 while ((__cfqq = new_cfqq->new_cfqq)) {
2474 process_refs = cfqq_process_refs(cfqq);
2475 new_process_refs = cfqq_process_refs(new_cfqq);
2477 * If the process for the cfqq has gone away, there is no
2478 * sense in merging the queues.
2480 if (process_refs == 0 || new_process_refs == 0)
2484 * Merge in the direction of the lesser amount of work.
2486 if (new_process_refs >= process_refs) {
2487 cfqq->new_cfqq = new_cfqq;
2488 new_cfqq->ref += process_refs;
2490 new_cfqq->new_cfqq = cfqq;
2491 cfqq->ref += new_process_refs;
2495 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2496 struct cfq_group *cfqg, enum wl_prio_t prio)
2498 struct cfq_queue *queue;
2500 bool key_valid = false;
2501 unsigned long lowest_key = 0;
2502 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2504 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2505 /* select the one with lowest rb_key */
2506 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2508 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2509 lowest_key = queue->rb_key;
2518 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2522 struct cfq_rb_root *st;
2523 unsigned group_slice;
2524 enum wl_prio_t original_prio = cfqd->serving_prio;
2526 /* Choose next priority. RT > BE > IDLE */
2527 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2528 cfqd->serving_prio = RT_WORKLOAD;
2529 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2530 cfqd->serving_prio = BE_WORKLOAD;
2532 cfqd->serving_prio = IDLE_WORKLOAD;
2533 cfqd->workload_expires = jiffies + 1;
2537 if (original_prio != cfqd->serving_prio)
2541 * For RT and BE, we have to choose also the type
2542 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2545 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2549 * check workload expiration, and that we still have other queues ready
2551 if (count && !time_after(jiffies, cfqd->workload_expires))
2555 /* otherwise select new workload type */
2556 cfqd->serving_type =
2557 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2558 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2562 * the workload slice is computed as a fraction of target latency
2563 * proportional to the number of queues in that workload, over
2564 * all the queues in the same priority class
2566 group_slice = cfq_group_slice(cfqd, cfqg);
2568 slice = group_slice * count /
2569 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2570 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2572 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2576 * Async queues are currently system wide. Just taking
2577 * proportion of queues with-in same group will lead to higher
2578 * async ratio system wide as generally root group is going
2579 * to have higher weight. A more accurate thing would be to
2580 * calculate system wide asnc/sync ratio.
2582 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2583 tmp = tmp/cfqd->busy_queues;
2584 slice = min_t(unsigned, slice, tmp);
2586 /* async workload slice is scaled down according to
2587 * the sync/async slice ratio. */
2588 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2590 /* sync workload slice is at least 2 * cfq_slice_idle */
2591 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2593 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2594 cfq_log(cfqd, "workload slice:%d", slice);
2595 cfqd->workload_expires = jiffies + slice;
2598 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2600 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2601 struct cfq_group *cfqg;
2603 if (RB_EMPTY_ROOT(&st->rb))
2605 cfqg = cfq_rb_first_group(st);
2606 update_min_vdisktime(st);
2610 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2612 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2614 cfqd->serving_group = cfqg;
2616 /* Restore the workload type data */
2617 if (cfqg->saved_workload_slice) {
2618 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2619 cfqd->serving_type = cfqg->saved_workload;
2620 cfqd->serving_prio = cfqg->saved_serving_prio;
2622 cfqd->workload_expires = jiffies - 1;
2624 choose_service_tree(cfqd, cfqg);
2628 * Select a queue for service. If we have a current active queue,
2629 * check whether to continue servicing it, or retrieve and set a new one.
2631 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2633 struct cfq_queue *cfqq, *new_cfqq = NULL;
2635 cfqq = cfqd->active_queue;
2639 if (!cfqd->rq_queued)
2643 * We were waiting for group to get backlogged. Expire the queue
2645 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2649 * The active queue has run out of time, expire it and select new.
2651 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2653 * If slice had not expired at the completion of last request
2654 * we might not have turned on wait_busy flag. Don't expire
2655 * the queue yet. Allow the group to get backlogged.
2657 * The very fact that we have used the slice, that means we
2658 * have been idling all along on this queue and it should be
2659 * ok to wait for this request to complete.
2661 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2662 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2666 goto check_group_idle;
2670 * The active queue has requests and isn't expired, allow it to
2673 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2677 * If another queue has a request waiting within our mean seek
2678 * distance, let it run. The expire code will check for close
2679 * cooperators and put the close queue at the front of the service
2680 * tree. If possible, merge the expiring queue with the new cfqq.
2682 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2684 if (!cfqq->new_cfqq)
2685 cfq_setup_merge(cfqq, new_cfqq);
2690 * No requests pending. If the active queue still has requests in
2691 * flight or is idling for a new request, allow either of these
2692 * conditions to happen (or time out) before selecting a new queue.
2694 if (timer_pending(&cfqd->idle_slice_timer)) {
2700 * This is a deep seek queue, but the device is much faster than
2701 * the queue can deliver, don't idle
2703 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2704 (cfq_cfqq_slice_new(cfqq) ||
2705 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2706 cfq_clear_cfqq_deep(cfqq);
2707 cfq_clear_cfqq_idle_window(cfqq);
2710 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2716 * If group idle is enabled and there are requests dispatched from
2717 * this group, wait for requests to complete.
2720 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2721 cfqq->cfqg->dispatched &&
2722 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2728 cfq_slice_expired(cfqd, 0);
2731 * Current queue expired. Check if we have to switch to a new
2735 cfq_choose_cfqg(cfqd);
2737 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2742 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2746 while (cfqq->next_rq) {
2747 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2751 BUG_ON(!list_empty(&cfqq->fifo));
2753 /* By default cfqq is not expired if it is empty. Do it explicitly */
2754 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2759 * Drain our current requests. Used for barriers and when switching
2760 * io schedulers on-the-fly.
2762 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2764 struct cfq_queue *cfqq;
2767 /* Expire the timeslice of the current active queue first */
2768 cfq_slice_expired(cfqd, 0);
2769 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2770 __cfq_set_active_queue(cfqd, cfqq);
2771 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2774 BUG_ON(cfqd->busy_queues);
2776 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2780 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2781 struct cfq_queue *cfqq)
2783 /* the queue hasn't finished any request, can't estimate */
2784 if (cfq_cfqq_slice_new(cfqq))
2786 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2793 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2795 unsigned int max_dispatch;
2798 * Drain async requests before we start sync IO
2800 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2804 * If this is an async queue and we have sync IO in flight, let it wait
2806 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2809 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2810 if (cfq_class_idle(cfqq))
2814 * Does this cfqq already have too much IO in flight?
2816 if (cfqq->dispatched >= max_dispatch) {
2817 bool promote_sync = false;
2819 * idle queue must always only have a single IO in flight
2821 if (cfq_class_idle(cfqq))
2825 * If there is only one sync queue
2826 * we can ignore async queue here and give the sync
2827 * queue no dispatch limit. The reason is a sync queue can
2828 * preempt async queue, limiting the sync queue doesn't make
2829 * sense. This is useful for aiostress test.
2831 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2832 promote_sync = true;
2835 * We have other queues, don't allow more IO from this one
2837 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2842 * Sole queue user, no limit
2844 if (cfqd->busy_queues == 1 || promote_sync)
2848 * Normally we start throttling cfqq when cfq_quantum/2
2849 * requests have been dispatched. But we can drive
2850 * deeper queue depths at the beginning of slice
2851 * subjected to upper limit of cfq_quantum.
2853 max_dispatch = cfqd->cfq_quantum;
2857 * Async queues must wait a bit before being allowed dispatch.
2858 * We also ramp up the dispatch depth gradually for async IO,
2859 * based on the last sync IO we serviced
2861 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2862 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2865 depth = last_sync / cfqd->cfq_slice[1];
2866 if (!depth && !cfqq->dispatched)
2868 if (depth < max_dispatch)
2869 max_dispatch = depth;
2873 * If we're below the current max, allow a dispatch
2875 return cfqq->dispatched < max_dispatch;
2879 * Dispatch a request from cfqq, moving them to the request queue
2882 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2886 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2888 if (!cfq_may_dispatch(cfqd, cfqq))
2892 * follow expired path, else get first next available
2894 rq = cfq_check_fifo(cfqq);
2899 * insert request into driver dispatch list
2901 cfq_dispatch_insert(cfqd->queue, rq);
2903 if (!cfqd->active_cic) {
2904 struct cfq_io_cq *cic = RQ_CIC(rq);
2906 atomic_long_inc(&cic->icq.ioc->refcount);
2907 cfqd->active_cic = cic;
2914 * Find the cfqq that we need to service and move a request from that to the
2917 static int cfq_dispatch_requests(struct request_queue *q, int force)
2919 struct cfq_data *cfqd = q->elevator->elevator_data;
2920 struct cfq_queue *cfqq;
2922 if (!cfqd->busy_queues)
2925 if (unlikely(force))
2926 return cfq_forced_dispatch(cfqd);
2928 cfqq = cfq_select_queue(cfqd);
2933 * Dispatch a request from this cfqq, if it is allowed
2935 if (!cfq_dispatch_request(cfqd, cfqq))
2938 cfqq->slice_dispatch++;
2939 cfq_clear_cfqq_must_dispatch(cfqq);
2942 * expire an async queue immediately if it has used up its slice. idle
2943 * queue always expire after 1 dispatch round.
2945 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2946 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2947 cfq_class_idle(cfqq))) {
2948 cfqq->slice_end = jiffies + 1;
2949 cfq_slice_expired(cfqd, 0);
2952 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2957 * task holds one reference to the queue, dropped when task exits. each rq
2958 * in-flight on this queue also holds a reference, dropped when rq is freed.
2960 * Each cfq queue took a reference on the parent group. Drop it now.
2961 * queue lock must be held here.
2963 static void cfq_put_queue(struct cfq_queue *cfqq)
2965 struct cfq_data *cfqd = cfqq->cfqd;
2966 struct cfq_group *cfqg;
2968 BUG_ON(cfqq->ref <= 0);
2974 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2975 BUG_ON(rb_first(&cfqq->sort_list));
2976 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2979 if (unlikely(cfqd->active_queue == cfqq)) {
2980 __cfq_slice_expired(cfqd, cfqq, 0);
2981 cfq_schedule_dispatch(cfqd);
2984 BUG_ON(cfq_cfqq_on_rr(cfqq));
2985 kmem_cache_free(cfq_pool, cfqq);
2989 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2991 struct cfq_queue *__cfqq, *next;
2994 * If this queue was scheduled to merge with another queue, be
2995 * sure to drop the reference taken on that queue (and others in
2996 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2998 __cfqq = cfqq->new_cfqq;
3000 if (__cfqq == cfqq) {
3001 WARN(1, "cfqq->new_cfqq loop detected\n");
3004 next = __cfqq->new_cfqq;
3005 cfq_put_queue(__cfqq);
3010 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3012 if (unlikely(cfqq == cfqd->active_queue)) {
3013 __cfq_slice_expired(cfqd, cfqq, 0);
3014 cfq_schedule_dispatch(cfqd);
3017 cfq_put_cooperator(cfqq);
3019 cfq_put_queue(cfqq);
3022 static void cfq_init_icq(struct io_cq *icq)
3024 struct cfq_io_cq *cic = icq_to_cic(icq);
3026 cic->ttime.last_end_request = jiffies;
3029 static void cfq_exit_icq(struct io_cq *icq)
3031 struct cfq_io_cq *cic = icq_to_cic(icq);
3032 struct cfq_data *cfqd = cic_to_cfqd(cic);
3034 if (cic->cfqq[BLK_RW_ASYNC]) {
3035 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3036 cic->cfqq[BLK_RW_ASYNC] = NULL;
3039 if (cic->cfqq[BLK_RW_SYNC]) {
3040 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3041 cic->cfqq[BLK_RW_SYNC] = NULL;
3045 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3047 struct task_struct *tsk = current;
3050 if (!cfq_cfqq_prio_changed(cfqq))
3053 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3054 switch (ioprio_class) {
3056 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3057 case IOPRIO_CLASS_NONE:
3059 * no prio set, inherit CPU scheduling settings
3061 cfqq->ioprio = task_nice_ioprio(tsk);
3062 cfqq->ioprio_class = task_nice_ioclass(tsk);
3064 case IOPRIO_CLASS_RT:
3065 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3066 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3068 case IOPRIO_CLASS_BE:
3069 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3070 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3072 case IOPRIO_CLASS_IDLE:
3073 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3075 cfq_clear_cfqq_idle_window(cfqq);
3080 * keep track of original prio settings in case we have to temporarily
3081 * elevate the priority of this queue
3083 cfqq->org_ioprio = cfqq->ioprio;
3084 cfq_clear_cfqq_prio_changed(cfqq);
3087 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3089 int ioprio = cic->icq.ioc->ioprio;
3090 struct cfq_data *cfqd = cic_to_cfqd(cic);
3091 struct cfq_queue *cfqq;
3094 * Check whether ioprio has changed. The condition may trigger
3095 * spuriously on a newly created cic but there's no harm.
3097 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3100 cfqq = cic->cfqq[BLK_RW_ASYNC];
3102 struct cfq_queue *new_cfqq;
3103 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3106 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3107 cfq_put_queue(cfqq);
3111 cfqq = cic->cfqq[BLK_RW_SYNC];
3113 cfq_mark_cfqq_prio_changed(cfqq);
3115 cic->ioprio = ioprio;
3118 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3119 pid_t pid, bool is_sync)
3121 RB_CLEAR_NODE(&cfqq->rb_node);
3122 RB_CLEAR_NODE(&cfqq->p_node);
3123 INIT_LIST_HEAD(&cfqq->fifo);
3128 cfq_mark_cfqq_prio_changed(cfqq);
3131 if (!cfq_class_idle(cfqq))
3132 cfq_mark_cfqq_idle_window(cfqq);
3133 cfq_mark_cfqq_sync(cfqq);
3138 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3139 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3141 struct cfq_data *cfqd = cic_to_cfqd(cic);
3142 struct cfq_queue *sync_cfqq;
3146 id = bio_blkcg(bio)->id;
3150 * Check whether blkcg has changed. The condition may trigger
3151 * spuriously on a newly created cic but there's no harm.
3153 if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3156 sync_cfqq = cic_to_cfqq(cic, 1);
3159 * Drop reference to sync queue. A new sync queue will be
3160 * assigned in new group upon arrival of a fresh request.
3162 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3163 cic_set_cfqq(cic, NULL, 1);
3164 cfq_put_queue(sync_cfqq);
3170 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3171 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3173 static struct cfq_queue *
3174 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3175 struct bio *bio, gfp_t gfp_mask)
3177 struct blkcg *blkcg;
3178 struct cfq_queue *cfqq, *new_cfqq = NULL;
3179 struct cfq_group *cfqg;
3184 blkcg = bio_blkcg(bio);
3185 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3186 cfqq = cic_to_cfqq(cic, is_sync);
3189 * Always try a new alloc if we fell back to the OOM cfqq
3190 * originally, since it should just be a temporary situation.
3192 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3197 } else if (gfp_mask & __GFP_WAIT) {
3199 spin_unlock_irq(cfqd->queue->queue_lock);
3200 new_cfqq = kmem_cache_alloc_node(cfq_pool,
3201 gfp_mask | __GFP_ZERO,
3203 spin_lock_irq(cfqd->queue->queue_lock);
3207 cfqq = kmem_cache_alloc_node(cfq_pool,
3208 gfp_mask | __GFP_ZERO,
3213 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3214 cfq_init_prio_data(cfqq, cic);
3215 cfq_link_cfqq_cfqg(cfqq, cfqg);
3216 cfq_log_cfqq(cfqd, cfqq, "alloced");
3218 cfqq = &cfqd->oom_cfqq;
3222 kmem_cache_free(cfq_pool, new_cfqq);
3228 static struct cfq_queue **
3229 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3231 switch (ioprio_class) {
3232 case IOPRIO_CLASS_RT:
3233 return &cfqd->async_cfqq[0][ioprio];
3234 case IOPRIO_CLASS_NONE:
3235 ioprio = IOPRIO_NORM;
3237 case IOPRIO_CLASS_BE:
3238 return &cfqd->async_cfqq[1][ioprio];
3239 case IOPRIO_CLASS_IDLE:
3240 return &cfqd->async_idle_cfqq;
3246 static struct cfq_queue *
3247 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3248 struct bio *bio, gfp_t gfp_mask)
3250 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3251 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3252 struct cfq_queue **async_cfqq = NULL;
3253 struct cfq_queue *cfqq = NULL;
3256 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3261 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3264 * pin the queue now that it's allocated, scheduler exit will prune it
3266 if (!is_sync && !(*async_cfqq)) {
3276 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3278 unsigned long elapsed = jiffies - ttime->last_end_request;
3279 elapsed = min(elapsed, 2UL * slice_idle);
3281 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3282 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3283 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3287 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3288 struct cfq_io_cq *cic)
3290 if (cfq_cfqq_sync(cfqq)) {
3291 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3292 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3293 cfqd->cfq_slice_idle);
3295 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3296 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3301 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3305 sector_t n_sec = blk_rq_sectors(rq);
3306 if (cfqq->last_request_pos) {
3307 if (cfqq->last_request_pos < blk_rq_pos(rq))
3308 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3310 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3313 cfqq->seek_history <<= 1;
3314 if (blk_queue_nonrot(cfqd->queue))
3315 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3317 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3321 * Disable idle window if the process thinks too long or seeks so much that
3325 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3326 struct cfq_io_cq *cic)
3328 int old_idle, enable_idle;
3331 * Don't idle for async or idle io prio class
3333 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3336 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3338 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3339 cfq_mark_cfqq_deep(cfqq);
3341 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3343 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3344 !cfqd->cfq_slice_idle ||
3345 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3347 else if (sample_valid(cic->ttime.ttime_samples)) {
3348 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3354 if (old_idle != enable_idle) {
3355 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3357 cfq_mark_cfqq_idle_window(cfqq);
3359 cfq_clear_cfqq_idle_window(cfqq);
3364 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3365 * no or if we aren't sure, a 1 will cause a preempt.
3368 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3371 struct cfq_queue *cfqq;
3373 cfqq = cfqd->active_queue;
3377 if (cfq_class_idle(new_cfqq))
3380 if (cfq_class_idle(cfqq))
3384 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3386 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3390 * if the new request is sync, but the currently running queue is
3391 * not, let the sync request have priority.
3393 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3396 if (new_cfqq->cfqg != cfqq->cfqg)
3399 if (cfq_slice_used(cfqq))
3402 /* Allow preemption only if we are idling on sync-noidle tree */
3403 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3404 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3405 new_cfqq->service_tree->count == 2 &&
3406 RB_EMPTY_ROOT(&cfqq->sort_list))
3410 * So both queues are sync. Let the new request get disk time if
3411 * it's a metadata request and the current queue is doing regular IO.
3413 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3417 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3419 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3422 /* An idle queue should not be idle now for some reason */
3423 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3426 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3430 * if this request is as-good as one we would expect from the
3431 * current cfqq, let it preempt
3433 if (cfq_rq_close(cfqd, cfqq, rq))
3440 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3441 * let it have half of its nominal slice.
3443 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3445 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3447 cfq_log_cfqq(cfqd, cfqq, "preempt");
3448 cfq_slice_expired(cfqd, 1);
3451 * workload type is changed, don't save slice, otherwise preempt
3454 if (old_type != cfqq_type(cfqq))
3455 cfqq->cfqg->saved_workload_slice = 0;
3458 * Put the new queue at the front of the of the current list,
3459 * so we know that it will be selected next.
3461 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3463 cfq_service_tree_add(cfqd, cfqq, 1);
3465 cfqq->slice_end = 0;
3466 cfq_mark_cfqq_slice_new(cfqq);
3470 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3471 * something we should do about it
3474 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3477 struct cfq_io_cq *cic = RQ_CIC(rq);
3480 if (rq->cmd_flags & REQ_PRIO)
3481 cfqq->prio_pending++;
3483 cfq_update_io_thinktime(cfqd, cfqq, cic);
3484 cfq_update_io_seektime(cfqd, cfqq, rq);
3485 cfq_update_idle_window(cfqd, cfqq, cic);
3487 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3489 if (cfqq == cfqd->active_queue) {
3491 * Remember that we saw a request from this process, but
3492 * don't start queuing just yet. Otherwise we risk seeing lots
3493 * of tiny requests, because we disrupt the normal plugging
3494 * and merging. If the request is already larger than a single
3495 * page, let it rip immediately. For that case we assume that
3496 * merging is already done. Ditto for a busy system that
3497 * has other work pending, don't risk delaying until the
3498 * idle timer unplug to continue working.
3500 if (cfq_cfqq_wait_request(cfqq)) {
3501 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3502 cfqd->busy_queues > 1) {
3503 cfq_del_timer(cfqd, cfqq);
3504 cfq_clear_cfqq_wait_request(cfqq);
3505 __blk_run_queue(cfqd->queue);
3507 cfqg_stats_update_idle_time(cfqq->cfqg);
3508 cfq_mark_cfqq_must_dispatch(cfqq);
3511 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3513 * not the active queue - expire current slice if it is
3514 * idle and has expired it's mean thinktime or this new queue
3515 * has some old slice time left and is of higher priority or
3516 * this new queue is RT and the current one is BE
3518 cfq_preempt_queue(cfqd, cfqq);
3519 __blk_run_queue(cfqd->queue);
3523 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3525 struct cfq_data *cfqd = q->elevator->elevator_data;
3526 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3528 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3529 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3531 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3532 list_add_tail(&rq->queuelist, &cfqq->fifo);
3534 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3536 cfq_rq_enqueued(cfqd, cfqq, rq);
3540 * Update hw_tag based on peak queue depth over 50 samples under
3543 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3545 struct cfq_queue *cfqq = cfqd->active_queue;
3547 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3548 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3550 if (cfqd->hw_tag == 1)
3553 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3554 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3558 * If active queue hasn't enough requests and can idle, cfq might not
3559 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3562 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3563 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3564 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3567 if (cfqd->hw_tag_samples++ < 50)
3570 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3576 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3578 struct cfq_io_cq *cic = cfqd->active_cic;
3580 /* If the queue already has requests, don't wait */
3581 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3584 /* If there are other queues in the group, don't wait */
3585 if (cfqq->cfqg->nr_cfqq > 1)
3588 /* the only queue in the group, but think time is big */
3589 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3592 if (cfq_slice_used(cfqq))
3595 /* if slice left is less than think time, wait busy */
3596 if (cic && sample_valid(cic->ttime.ttime_samples)
3597 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3601 * If think times is less than a jiffy than ttime_mean=0 and above
3602 * will not be true. It might happen that slice has not expired yet
3603 * but will expire soon (4-5 ns) during select_queue(). To cover the
3604 * case where think time is less than a jiffy, mark the queue wait
3605 * busy if only 1 jiffy is left in the slice.
3607 if (cfqq->slice_end - jiffies == 1)
3613 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3615 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3616 struct cfq_data *cfqd = cfqq->cfqd;
3617 const int sync = rq_is_sync(rq);
3621 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3622 !!(rq->cmd_flags & REQ_NOIDLE));
3624 cfq_update_hw_tag(cfqd);
3626 WARN_ON(!cfqd->rq_in_driver);
3627 WARN_ON(!cfqq->dispatched);
3628 cfqd->rq_in_driver--;
3630 (RQ_CFQG(rq))->dispatched--;
3631 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3632 rq_io_start_time_ns(rq), rq->cmd_flags);
3634 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3637 struct cfq_rb_root *service_tree;
3639 RQ_CIC(rq)->ttime.last_end_request = now;
3641 if (cfq_cfqq_on_rr(cfqq))
3642 service_tree = cfqq->service_tree;
3644 service_tree = service_tree_for(cfqq->cfqg,
3645 cfqq_prio(cfqq), cfqq_type(cfqq));
3646 service_tree->ttime.last_end_request = now;
3647 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3648 cfqd->last_delayed_sync = now;
3651 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3652 cfqq->cfqg->ttime.last_end_request = now;
3656 * If this is the active queue, check if it needs to be expired,
3657 * or if we want to idle in case it has no pending requests.
3659 if (cfqd->active_queue == cfqq) {
3660 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3662 if (cfq_cfqq_slice_new(cfqq)) {
3663 cfq_set_prio_slice(cfqd, cfqq);
3664 cfq_clear_cfqq_slice_new(cfqq);
3668 * Should we wait for next request to come in before we expire
3671 if (cfq_should_wait_busy(cfqd, cfqq)) {
3672 unsigned long extend_sl = cfqd->cfq_slice_idle;
3673 if (!cfqd->cfq_slice_idle)
3674 extend_sl = cfqd->cfq_group_idle;
3675 cfqq->slice_end = jiffies + extend_sl;
3676 cfq_mark_cfqq_wait_busy(cfqq);
3677 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3681 * Idling is not enabled on:
3683 * - idle-priority queues
3685 * - queues with still some requests queued
3686 * - when there is a close cooperator
3688 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3689 cfq_slice_expired(cfqd, 1);
3690 else if (sync && cfqq_empty &&
3691 !cfq_close_cooperator(cfqd, cfqq)) {
3692 cfq_arm_slice_timer(cfqd);
3696 if (!cfqd->rq_in_driver)
3697 cfq_schedule_dispatch(cfqd);
3700 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3702 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3703 cfq_mark_cfqq_must_alloc_slice(cfqq);
3704 return ELV_MQUEUE_MUST;
3707 return ELV_MQUEUE_MAY;
3710 static int cfq_may_queue(struct request_queue *q, int rw)
3712 struct cfq_data *cfqd = q->elevator->elevator_data;
3713 struct task_struct *tsk = current;
3714 struct cfq_io_cq *cic;
3715 struct cfq_queue *cfqq;
3718 * don't force setup of a queue from here, as a call to may_queue
3719 * does not necessarily imply that a request actually will be queued.
3720 * so just lookup a possibly existing queue, or return 'may queue'
3723 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3725 return ELV_MQUEUE_MAY;
3727 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3729 cfq_init_prio_data(cfqq, cic);
3731 return __cfq_may_queue(cfqq);
3734 return ELV_MQUEUE_MAY;
3738 * queue lock held here
3740 static void cfq_put_request(struct request *rq)
3742 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3745 const int rw = rq_data_dir(rq);
3747 BUG_ON(!cfqq->allocated[rw]);
3748 cfqq->allocated[rw]--;
3750 /* Put down rq reference on cfqg */
3751 cfqg_put(RQ_CFQG(rq));
3752 rq->elv.priv[0] = NULL;
3753 rq->elv.priv[1] = NULL;
3755 cfq_put_queue(cfqq);
3759 static struct cfq_queue *
3760 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3761 struct cfq_queue *cfqq)
3763 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3764 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3765 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3766 cfq_put_queue(cfqq);
3767 return cic_to_cfqq(cic, 1);
3771 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3772 * was the last process referring to said cfqq.
3774 static struct cfq_queue *
3775 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3777 if (cfqq_process_refs(cfqq) == 1) {
3778 cfqq->pid = current->pid;
3779 cfq_clear_cfqq_coop(cfqq);
3780 cfq_clear_cfqq_split_coop(cfqq);
3784 cic_set_cfqq(cic, NULL, 1);
3786 cfq_put_cooperator(cfqq);
3788 cfq_put_queue(cfqq);
3792 * Allocate cfq data structures associated with this request.
3795 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3798 struct cfq_data *cfqd = q->elevator->elevator_data;
3799 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3800 const int rw = rq_data_dir(rq);
3801 const bool is_sync = rq_is_sync(rq);
3802 struct cfq_queue *cfqq;
3804 might_sleep_if(gfp_mask & __GFP_WAIT);
3806 spin_lock_irq(q->queue_lock);
3808 check_ioprio_changed(cic, bio);
3809 check_blkcg_changed(cic, bio);
3811 cfqq = cic_to_cfqq(cic, is_sync);
3812 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3813 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3814 cic_set_cfqq(cic, cfqq, is_sync);
3817 * If the queue was seeky for too long, break it apart.
3819 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3820 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3821 cfqq = split_cfqq(cic, cfqq);
3827 * Check to see if this queue is scheduled to merge with
3828 * another, closely cooperating queue. The merging of
3829 * queues happens here as it must be done in process context.
3830 * The reference on new_cfqq was taken in merge_cfqqs.
3833 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3836 cfqq->allocated[rw]++;
3839 cfqg_get(cfqq->cfqg);
3840 rq->elv.priv[0] = cfqq;
3841 rq->elv.priv[1] = cfqq->cfqg;
3842 spin_unlock_irq(q->queue_lock);
3846 static void cfq_kick_queue(struct work_struct *work)
3848 struct cfq_data *cfqd =
3849 container_of(work, struct cfq_data, unplug_work);
3850 struct request_queue *q = cfqd->queue;
3852 spin_lock_irq(q->queue_lock);
3853 __blk_run_queue(cfqd->queue);
3854 spin_unlock_irq(q->queue_lock);
3858 * Timer running if the active_queue is currently idling inside its time slice
3860 static void cfq_idle_slice_timer(unsigned long data)
3862 struct cfq_data *cfqd = (struct cfq_data *) data;
3863 struct cfq_queue *cfqq;
3864 unsigned long flags;
3867 cfq_log(cfqd, "idle timer fired");
3869 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3871 cfqq = cfqd->active_queue;
3876 * We saw a request before the queue expired, let it through
3878 if (cfq_cfqq_must_dispatch(cfqq))
3884 if (cfq_slice_used(cfqq))
3888 * only expire and reinvoke request handler, if there are
3889 * other queues with pending requests
3891 if (!cfqd->busy_queues)
3895 * not expired and it has a request pending, let it dispatch
3897 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3901 * Queue depth flag is reset only when the idle didn't succeed
3903 cfq_clear_cfqq_deep(cfqq);
3906 cfq_slice_expired(cfqd, timed_out);
3908 cfq_schedule_dispatch(cfqd);
3910 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3913 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3915 del_timer_sync(&cfqd->idle_slice_timer);
3916 cancel_work_sync(&cfqd->unplug_work);
3919 static void cfq_put_async_queues(struct cfq_data *cfqd)
3923 for (i = 0; i < IOPRIO_BE_NR; i++) {
3924 if (cfqd->async_cfqq[0][i])
3925 cfq_put_queue(cfqd->async_cfqq[0][i]);
3926 if (cfqd->async_cfqq[1][i])
3927 cfq_put_queue(cfqd->async_cfqq[1][i]);
3930 if (cfqd->async_idle_cfqq)
3931 cfq_put_queue(cfqd->async_idle_cfqq);
3934 static void cfq_exit_queue(struct elevator_queue *e)
3936 struct cfq_data *cfqd = e->elevator_data;
3937 struct request_queue *q = cfqd->queue;
3939 cfq_shutdown_timer_wq(cfqd);
3941 spin_lock_irq(q->queue_lock);
3943 if (cfqd->active_queue)
3944 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3946 cfq_put_async_queues(cfqd);
3948 spin_unlock_irq(q->queue_lock);
3950 cfq_shutdown_timer_wq(cfqd);
3952 #ifndef CONFIG_CFQ_GROUP_IOSCHED
3953 kfree(cfqd->root_group);
3955 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
3959 static int cfq_init_queue(struct request_queue *q)
3961 struct cfq_data *cfqd;
3962 struct blkcg_gq *blkg __maybe_unused;
3965 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3970 q->elevator->elevator_data = cfqd;
3972 /* Init root service tree */
3973 cfqd->grp_service_tree = CFQ_RB_ROOT;
3975 /* Init root group and prefer root group over other groups by default */
3976 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3977 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
3981 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
3984 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3985 GFP_KERNEL, cfqd->queue->node);
3986 if (!cfqd->root_group)
3989 cfq_init_cfqg_base(cfqd->root_group);
3991 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3994 * Not strictly needed (since RB_ROOT just clears the node and we
3995 * zeroed cfqd on alloc), but better be safe in case someone decides
3996 * to add magic to the rb code
3998 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3999 cfqd->prio_trees[i] = RB_ROOT;
4002 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4003 * Grab a permanent reference to it, so that the normal code flow
4004 * will not attempt to free it. oom_cfqq is linked to root_group
4005 * but shouldn't hold a reference as it'll never be unlinked. Lose
4006 * the reference from linking right away.
4008 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4009 cfqd->oom_cfqq.ref++;
4011 spin_lock_irq(q->queue_lock);
4012 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4013 cfqg_put(cfqd->root_group);
4014 spin_unlock_irq(q->queue_lock);
4016 init_timer(&cfqd->idle_slice_timer);
4017 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4018 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4020 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4022 cfqd->cfq_quantum = cfq_quantum;
4023 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4024 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4025 cfqd->cfq_back_max = cfq_back_max;
4026 cfqd->cfq_back_penalty = cfq_back_penalty;
4027 cfqd->cfq_slice[0] = cfq_slice_async;
4028 cfqd->cfq_slice[1] = cfq_slice_sync;
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 #undef SHOW_FUNCTION
4086 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4087 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4089 struct cfq_data *cfqd = e->elevator_data; \
4090 unsigned int __data; \
4091 int ret = cfq_var_store(&__data, (page), count); \
4092 if (__data < (MIN)) \
4094 else if (__data > (MAX)) \
4097 *(__PTR) = msecs_to_jiffies(__data); \
4099 *(__PTR) = __data; \
4102 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4103 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4105 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4107 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4108 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4110 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4111 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4112 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4113 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4114 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4116 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4117 #undef STORE_FUNCTION
4119 #define CFQ_ATTR(name) \
4120 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4122 static struct elv_fs_entry cfq_attrs[] = {
4124 CFQ_ATTR(fifo_expire_sync),
4125 CFQ_ATTR(fifo_expire_async),
4126 CFQ_ATTR(back_seek_max),
4127 CFQ_ATTR(back_seek_penalty),
4128 CFQ_ATTR(slice_sync),
4129 CFQ_ATTR(slice_async),
4130 CFQ_ATTR(slice_async_rq),
4131 CFQ_ATTR(slice_idle),
4132 CFQ_ATTR(group_idle),
4133 CFQ_ATTR(low_latency),
4137 static struct elevator_type iosched_cfq = {
4139 .elevator_merge_fn = cfq_merge,
4140 .elevator_merged_fn = cfq_merged_request,
4141 .elevator_merge_req_fn = cfq_merged_requests,
4142 .elevator_allow_merge_fn = cfq_allow_merge,
4143 .elevator_bio_merged_fn = cfq_bio_merged,
4144 .elevator_dispatch_fn = cfq_dispatch_requests,
4145 .elevator_add_req_fn = cfq_insert_request,
4146 .elevator_activate_req_fn = cfq_activate_request,
4147 .elevator_deactivate_req_fn = cfq_deactivate_request,
4148 .elevator_completed_req_fn = cfq_completed_request,
4149 .elevator_former_req_fn = elv_rb_former_request,
4150 .elevator_latter_req_fn = elv_rb_latter_request,
4151 .elevator_init_icq_fn = cfq_init_icq,
4152 .elevator_exit_icq_fn = cfq_exit_icq,
4153 .elevator_set_req_fn = cfq_set_request,
4154 .elevator_put_req_fn = cfq_put_request,
4155 .elevator_may_queue_fn = cfq_may_queue,
4156 .elevator_init_fn = cfq_init_queue,
4157 .elevator_exit_fn = cfq_exit_queue,
4159 .icq_size = sizeof(struct cfq_io_cq),
4160 .icq_align = __alignof__(struct cfq_io_cq),
4161 .elevator_attrs = cfq_attrs,
4162 .elevator_name = "cfq",
4163 .elevator_owner = THIS_MODULE,
4166 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4167 static struct blkcg_policy blkcg_policy_cfq = {
4169 .pd_init_fn = cfq_pd_init,
4170 .pd_reset_stats_fn = cfq_pd_reset_stats,
4172 .pd_size = sizeof(struct cfq_group),
4173 .cftypes = cfq_blkcg_files,
4177 static int __init cfq_init(void)
4182 * could be 0 on HZ < 1000 setups
4184 if (!cfq_slice_async)
4185 cfq_slice_async = 1;
4186 if (!cfq_slice_idle)
4189 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4190 if (!cfq_group_idle)
4196 ret = blkcg_policy_register(&blkcg_policy_cfq);
4200 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4204 ret = elv_register(&iosched_cfq);
4211 kmem_cache_destroy(cfq_pool);
4213 blkcg_policy_unregister(&blkcg_policy_cfq);
4217 static void __exit cfq_exit(void)
4219 blkcg_policy_unregister(&blkcg_policy_cfq);
4220 elv_unregister(&iosched_cfq);
4221 kmem_cache_destroy(cfq_pool);
4224 module_init(cfq_init);
4225 module_exit(cfq_exit);
4227 MODULE_AUTHOR("Jens Axboe");
4228 MODULE_LICENSE("GPL");
4229 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");