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>
17 #include <linux/blk-cgroup.h>
23 /* max queue in one round of service */
24 static const int cfq_quantum = 8;
25 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max = 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty = 2;
30 static const int cfq_slice_sync = HZ / 10;
31 static int cfq_slice_async = HZ / 25;
32 static const int cfq_slice_async_rq = 2;
33 static int cfq_slice_idle = HZ / 125;
34 static int cfq_group_idle = HZ / 125;
35 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36 static const int cfq_hist_divisor = 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache *cfq_pool;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
70 /* blkio-related constants */
71 #define CFQ_WEIGHT_MIN 10
72 #define CFQ_WEIGHT_MAX 1000
73 #define CFQ_WEIGHT_DEFAULT 500
76 unsigned long last_end_request;
78 unsigned long ttime_total;
79 unsigned long ttime_samples;
80 unsigned long ttime_mean;
84 * Most of our rbtree usage is for sorting with min extraction, so
85 * if we cache the leftmost node we don't have to walk down the tree
86 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
87 * move this into the elevator for the rq sorting as well.
94 struct cfq_ttime ttime;
96 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
97 .ttime = {.last_end_request = jiffies,},}
100 * Per process-grouping structure
103 /* reference count */
105 /* various state flags, see below */
107 /* parent cfq_data */
108 struct cfq_data *cfqd;
109 /* service_tree member */
110 struct rb_node rb_node;
111 /* service_tree key */
112 unsigned long rb_key;
113 /* prio tree member */
114 struct rb_node p_node;
115 /* prio tree root we belong to, if any */
116 struct rb_root *p_root;
117 /* sorted list of pending requests */
118 struct rb_root sort_list;
119 /* if fifo isn't expired, next request to serve */
120 struct request *next_rq;
121 /* requests queued in sort_list */
123 /* currently allocated requests */
125 /* fifo list of requests in sort_list */
126 struct list_head fifo;
128 /* time when queue got scheduled in to dispatch first request. */
129 unsigned long dispatch_start;
130 unsigned int allocated_slice;
131 unsigned int slice_dispatch;
132 /* time when first request from queue completed and slice started. */
133 unsigned long slice_start;
134 unsigned long slice_end;
137 /* pending priority requests */
139 /* number of requests that are on the dispatch list or inside driver */
142 /* io prio of this group */
143 unsigned short ioprio, org_ioprio;
144 unsigned short ioprio_class;
149 sector_t last_request_pos;
151 struct cfq_rb_root *service_tree;
152 struct cfq_queue *new_cfqq;
153 struct cfq_group *cfqg;
154 /* Number of sectors dispatched from queue in single dispatch round */
155 unsigned long nr_sectors;
159 * First index in the service_trees.
160 * IDLE is handled separately, so it has negative index
170 * Second index in the service_trees.
174 SYNC_NOIDLE_WORKLOAD = 1,
179 #ifdef CONFIG_CFQ_GROUP_IOSCHED
180 /* total bytes transferred */
181 struct blkg_rwstat service_bytes;
182 /* total IOs serviced, post merge */
183 struct blkg_rwstat serviced;
184 /* number of ios merged */
185 struct blkg_rwstat merged;
186 /* total time spent on device in ns, may not be accurate w/ queueing */
187 struct blkg_rwstat service_time;
188 /* total time spent waiting in scheduler queue in ns */
189 struct blkg_rwstat wait_time;
190 /* number of IOs queued up */
191 struct blkg_rwstat queued;
192 /* total sectors transferred */
193 struct blkg_stat sectors;
194 /* total disk time and nr sectors dispatched by this group */
195 struct blkg_stat time;
196 #ifdef CONFIG_DEBUG_BLK_CGROUP
197 /* time not charged to this cgroup */
198 struct blkg_stat unaccounted_time;
199 /* sum of number of ios queued across all samples */
200 struct blkg_stat avg_queue_size_sum;
201 /* count of samples taken for average */
202 struct blkg_stat avg_queue_size_samples;
203 /* how many times this group has been removed from service tree */
204 struct blkg_stat dequeue;
205 /* total time spent waiting for it to be assigned a timeslice. */
206 struct blkg_stat group_wait_time;
207 /* time spent idling for this blkcg_gq */
208 struct blkg_stat idle_time;
209 /* total time with empty current active q with other requests queued */
210 struct blkg_stat empty_time;
211 /* fields after this shouldn't be cleared on stat reset */
212 uint64_t start_group_wait_time;
213 uint64_t start_idle_time;
214 uint64_t start_empty_time;
216 #endif /* CONFIG_DEBUG_BLK_CGROUP */
217 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
220 /* Per-cgroup data */
221 struct cfq_group_data {
222 /* must be the first member */
223 struct blkcg_policy_data cpd;
226 unsigned int leaf_weight;
229 /* This is per cgroup per device grouping structure */
231 /* must be the first member */
232 struct blkg_policy_data pd;
234 /* group service_tree member */
235 struct rb_node rb_node;
237 /* group service_tree key */
241 * The number of active cfqgs and sum of their weights under this
242 * cfqg. This covers this cfqg's leaf_weight and all children's
243 * weights, but does not cover weights of further descendants.
245 * If a cfqg is on the service tree, it's active. An active cfqg
246 * also activates its parent and contributes to the children_weight
250 unsigned int children_weight;
253 * vfraction is the fraction of vdisktime that the tasks in this
254 * cfqg are entitled to. This is determined by compounding the
255 * ratios walking up from this cfqg to the root.
257 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
258 * vfractions on a service tree is approximately 1. The sum may
259 * deviate a bit due to rounding errors and fluctuations caused by
260 * cfqgs entering and leaving the service tree.
262 unsigned int vfraction;
265 * There are two weights - (internal) weight is the weight of this
266 * cfqg against the sibling cfqgs. leaf_weight is the wight of
267 * this cfqg against the child cfqgs. For the root cfqg, both
268 * weights are kept in sync for backward compatibility.
271 unsigned int new_weight;
272 unsigned int dev_weight;
274 unsigned int leaf_weight;
275 unsigned int new_leaf_weight;
276 unsigned int dev_leaf_weight;
278 /* number of cfqq currently on this group */
282 * Per group busy queues average. Useful for workload slice calc. We
283 * create the array for each prio class but at run time it is used
284 * only for RT and BE class and slot for IDLE class remains unused.
285 * This is primarily done to avoid confusion and a gcc warning.
287 unsigned int busy_queues_avg[CFQ_PRIO_NR];
289 * rr lists of queues with requests. We maintain service trees for
290 * RT and BE classes. These trees are subdivided in subclasses
291 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
292 * class there is no subclassification and all the cfq queues go on
293 * a single tree service_tree_idle.
294 * Counts are embedded in the cfq_rb_root
296 struct cfq_rb_root service_trees[2][3];
297 struct cfq_rb_root service_tree_idle;
299 unsigned long saved_wl_slice;
300 enum wl_type_t saved_wl_type;
301 enum wl_class_t saved_wl_class;
303 /* number of requests that are on the dispatch list or inside driver */
305 struct cfq_ttime ttime;
306 struct cfqg_stats stats; /* stats for this cfqg */
308 /* async queue for each priority case */
309 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
310 struct cfq_queue *async_idle_cfqq;
315 struct io_cq icq; /* must be the first member */
316 struct cfq_queue *cfqq[2];
317 struct cfq_ttime ttime;
318 int ioprio; /* the current ioprio */
319 #ifdef CONFIG_CFQ_GROUP_IOSCHED
320 uint64_t blkcg_serial_nr; /* the current blkcg serial */
325 * Per block device queue structure
328 struct request_queue *queue;
329 /* Root service tree for cfq_groups */
330 struct cfq_rb_root grp_service_tree;
331 struct cfq_group *root_group;
334 * The priority currently being served
336 enum wl_class_t serving_wl_class;
337 enum wl_type_t serving_wl_type;
338 unsigned long workload_expires;
339 struct cfq_group *serving_group;
342 * Each priority tree is sorted by next_request position. These
343 * trees are used when determining if two or more queues are
344 * interleaving requests (see cfq_close_cooperator).
346 struct rb_root prio_trees[CFQ_PRIO_LISTS];
348 unsigned int busy_queues;
349 unsigned int busy_sync_queues;
355 * queue-depth detection
361 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
362 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
365 int hw_tag_est_depth;
366 unsigned int hw_tag_samples;
369 * idle window management
371 struct timer_list idle_slice_timer;
372 struct work_struct unplug_work;
374 struct cfq_queue *active_queue;
375 struct cfq_io_cq *active_cic;
377 sector_t last_position;
380 * tunables, see top of file
382 unsigned int cfq_quantum;
383 unsigned int cfq_fifo_expire[2];
384 unsigned int cfq_back_penalty;
385 unsigned int cfq_back_max;
386 unsigned int cfq_slice[2];
387 unsigned int cfq_slice_async_rq;
388 unsigned int cfq_slice_idle;
389 unsigned int cfq_group_idle;
390 unsigned int cfq_latency;
391 unsigned int cfq_target_latency;
394 * Fallback dummy cfqq for extreme OOM conditions
396 struct cfq_queue oom_cfqq;
398 unsigned long last_delayed_sync;
401 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
402 static void cfq_put_queue(struct cfq_queue *cfqq);
404 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
405 enum wl_class_t class,
411 if (class == IDLE_WORKLOAD)
412 return &cfqg->service_tree_idle;
414 return &cfqg->service_trees[class][type];
417 enum cfqq_state_flags {
418 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
419 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
420 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
421 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
422 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
423 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
424 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
425 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
426 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
427 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
428 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
429 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
430 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
433 #define CFQ_CFQQ_FNS(name) \
434 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
436 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
438 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
440 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
442 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
444 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
448 CFQ_CFQQ_FNS(wait_request);
449 CFQ_CFQQ_FNS(must_dispatch);
450 CFQ_CFQQ_FNS(must_alloc_slice);
451 CFQ_CFQQ_FNS(fifo_expire);
452 CFQ_CFQQ_FNS(idle_window);
453 CFQ_CFQQ_FNS(prio_changed);
454 CFQ_CFQQ_FNS(slice_new);
457 CFQ_CFQQ_FNS(split_coop);
459 CFQ_CFQQ_FNS(wait_busy);
462 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
464 /* cfqg stats flags */
465 enum cfqg_stats_flags {
466 CFQG_stats_waiting = 0,
471 #define CFQG_FLAG_FNS(name) \
472 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
474 stats->flags |= (1 << CFQG_stats_##name); \
476 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
478 stats->flags &= ~(1 << CFQG_stats_##name); \
480 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
482 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
485 CFQG_FLAG_FNS(waiting)
486 CFQG_FLAG_FNS(idling)
490 /* This should be called with the queue_lock held. */
491 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
493 unsigned long long now;
495 if (!cfqg_stats_waiting(stats))
499 if (time_after64(now, stats->start_group_wait_time))
500 blkg_stat_add(&stats->group_wait_time,
501 now - stats->start_group_wait_time);
502 cfqg_stats_clear_waiting(stats);
505 /* This should be called with the queue_lock held. */
506 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
507 struct cfq_group *curr_cfqg)
509 struct cfqg_stats *stats = &cfqg->stats;
511 if (cfqg_stats_waiting(stats))
513 if (cfqg == curr_cfqg)
515 stats->start_group_wait_time = sched_clock();
516 cfqg_stats_mark_waiting(stats);
519 /* This should be called with the queue_lock held. */
520 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
522 unsigned long long now;
524 if (!cfqg_stats_empty(stats))
528 if (time_after64(now, stats->start_empty_time))
529 blkg_stat_add(&stats->empty_time,
530 now - stats->start_empty_time);
531 cfqg_stats_clear_empty(stats);
534 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
536 blkg_stat_add(&cfqg->stats.dequeue, 1);
539 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
541 struct cfqg_stats *stats = &cfqg->stats;
543 if (blkg_rwstat_total(&stats->queued))
547 * group is already marked empty. This can happen if cfqq got new
548 * request in parent group and moved to this group while being added
549 * to service tree. Just ignore the event and move on.
551 if (cfqg_stats_empty(stats))
554 stats->start_empty_time = sched_clock();
555 cfqg_stats_mark_empty(stats);
558 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
560 struct cfqg_stats *stats = &cfqg->stats;
562 if (cfqg_stats_idling(stats)) {
563 unsigned long long now = sched_clock();
565 if (time_after64(now, stats->start_idle_time))
566 blkg_stat_add(&stats->idle_time,
567 now - stats->start_idle_time);
568 cfqg_stats_clear_idling(stats);
572 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
574 struct cfqg_stats *stats = &cfqg->stats;
576 BUG_ON(cfqg_stats_idling(stats));
578 stats->start_idle_time = sched_clock();
579 cfqg_stats_mark_idling(stats);
582 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
584 struct cfqg_stats *stats = &cfqg->stats;
586 blkg_stat_add(&stats->avg_queue_size_sum,
587 blkg_rwstat_total(&stats->queued));
588 blkg_stat_add(&stats->avg_queue_size_samples, 1);
589 cfqg_stats_update_group_wait_time(stats);
592 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
594 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
595 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
596 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
597 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
598 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
599 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
600 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
602 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
604 #ifdef CONFIG_CFQ_GROUP_IOSCHED
606 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
608 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
611 static struct cfq_group_data
612 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
614 return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
617 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
619 return pd_to_blkg(&cfqg->pd);
622 static struct blkcg_policy blkcg_policy_cfq;
624 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
626 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
629 static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
631 return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
634 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
636 struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
638 return pblkg ? blkg_to_cfqg(pblkg) : NULL;
641 static inline void cfqg_get(struct cfq_group *cfqg)
643 return blkg_get(cfqg_to_blkg(cfqg));
646 static inline void cfqg_put(struct cfq_group *cfqg)
648 return blkg_put(cfqg_to_blkg(cfqg));
651 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
654 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
655 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
656 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
657 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
661 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
664 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
665 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
668 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
669 struct cfq_group *curr_cfqg, int rw)
671 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
672 cfqg_stats_end_empty_time(&cfqg->stats);
673 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
676 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
677 unsigned long time, unsigned long unaccounted_time)
679 blkg_stat_add(&cfqg->stats.time, time);
680 #ifdef CONFIG_DEBUG_BLK_CGROUP
681 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
685 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
687 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
690 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
692 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
695 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
696 uint64_t bytes, int rw)
698 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
699 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
700 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
703 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
704 uint64_t start_time, uint64_t io_start_time, int rw)
706 struct cfqg_stats *stats = &cfqg->stats;
707 unsigned long long now = sched_clock();
709 if (time_after64(now, io_start_time))
710 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
711 if (time_after64(io_start_time, start_time))
712 blkg_rwstat_add(&stats->wait_time, rw,
713 io_start_time - start_time);
717 static void cfqg_stats_reset(struct cfqg_stats *stats)
719 /* queued stats shouldn't be cleared */
720 blkg_rwstat_reset(&stats->service_bytes);
721 blkg_rwstat_reset(&stats->serviced);
722 blkg_rwstat_reset(&stats->merged);
723 blkg_rwstat_reset(&stats->service_time);
724 blkg_rwstat_reset(&stats->wait_time);
725 blkg_stat_reset(&stats->time);
726 #ifdef CONFIG_DEBUG_BLK_CGROUP
727 blkg_stat_reset(&stats->unaccounted_time);
728 blkg_stat_reset(&stats->avg_queue_size_sum);
729 blkg_stat_reset(&stats->avg_queue_size_samples);
730 blkg_stat_reset(&stats->dequeue);
731 blkg_stat_reset(&stats->group_wait_time);
732 blkg_stat_reset(&stats->idle_time);
733 blkg_stat_reset(&stats->empty_time);
738 static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
740 /* queued stats shouldn't be cleared */
741 blkg_rwstat_add_aux(&to->service_bytes, &from->service_bytes);
742 blkg_rwstat_add_aux(&to->serviced, &from->serviced);
743 blkg_rwstat_add_aux(&to->merged, &from->merged);
744 blkg_rwstat_add_aux(&to->service_time, &from->service_time);
745 blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
746 blkg_stat_add_aux(&from->time, &from->time);
747 #ifdef CONFIG_DEBUG_BLK_CGROUP
748 blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
749 blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
750 blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
751 blkg_stat_add_aux(&to->dequeue, &from->dequeue);
752 blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
753 blkg_stat_add_aux(&to->idle_time, &from->idle_time);
754 blkg_stat_add_aux(&to->empty_time, &from->empty_time);
759 * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
760 * recursive stats can still account for the amount used by this cfqg after
763 static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
765 struct cfq_group *parent = cfqg_parent(cfqg);
767 lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
769 if (unlikely(!parent))
772 cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
773 cfqg_stats_reset(&cfqg->stats);
776 #else /* CONFIG_CFQ_GROUP_IOSCHED */
778 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
779 static inline void cfqg_get(struct cfq_group *cfqg) { }
780 static inline void cfqg_put(struct cfq_group *cfqg) { }
782 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
783 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
784 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
785 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
787 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
789 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
790 struct cfq_group *curr_cfqg, int rw) { }
791 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
792 unsigned long time, unsigned long unaccounted_time) { }
793 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
794 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
795 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
796 uint64_t bytes, int rw) { }
797 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
798 uint64_t start_time, uint64_t io_start_time, int rw) { }
800 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
802 #define cfq_log(cfqd, fmt, args...) \
803 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
805 /* Traverses through cfq group service trees */
806 #define for_each_cfqg_st(cfqg, i, j, st) \
807 for (i = 0; i <= IDLE_WORKLOAD; i++) \
808 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
809 : &cfqg->service_tree_idle; \
810 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
811 (i == IDLE_WORKLOAD && j == 0); \
812 j++, st = i < IDLE_WORKLOAD ? \
813 &cfqg->service_trees[i][j]: NULL) \
815 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
816 struct cfq_ttime *ttime, bool group_idle)
819 if (!sample_valid(ttime->ttime_samples))
822 slice = cfqd->cfq_group_idle;
824 slice = cfqd->cfq_slice_idle;
825 return ttime->ttime_mean > slice;
828 static inline bool iops_mode(struct cfq_data *cfqd)
831 * If we are not idling on queues and it is a NCQ drive, parallel
832 * execution of requests is on and measuring time is not possible
833 * in most of the cases until and unless we drive shallower queue
834 * depths and that becomes a performance bottleneck. In such cases
835 * switch to start providing fairness in terms of number of IOs.
837 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
843 static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
845 if (cfq_class_idle(cfqq))
846 return IDLE_WORKLOAD;
847 if (cfq_class_rt(cfqq))
853 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
855 if (!cfq_cfqq_sync(cfqq))
856 return ASYNC_WORKLOAD;
857 if (!cfq_cfqq_idle_window(cfqq))
858 return SYNC_NOIDLE_WORKLOAD;
859 return SYNC_WORKLOAD;
862 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
863 struct cfq_data *cfqd,
864 struct cfq_group *cfqg)
866 if (wl_class == IDLE_WORKLOAD)
867 return cfqg->service_tree_idle.count;
869 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
870 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
871 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
874 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
875 struct cfq_group *cfqg)
877 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
878 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
881 static void cfq_dispatch_insert(struct request_queue *, struct request *);
882 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
883 struct cfq_io_cq *cic, struct bio *bio);
885 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
887 /* cic->icq is the first member, %NULL will convert to %NULL */
888 return container_of(icq, struct cfq_io_cq, icq);
891 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
892 struct io_context *ioc)
895 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
899 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
901 return cic->cfqq[is_sync];
904 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
907 cic->cfqq[is_sync] = cfqq;
910 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
912 return cic->icq.q->elevator->elevator_data;
916 * We regard a request as SYNC, if it's either a read or has the SYNC bit
917 * set (in which case it could also be direct WRITE).
919 static inline bool cfq_bio_sync(struct bio *bio)
921 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
925 * scheduler run of queue, if there are requests pending and no one in the
926 * driver that will restart queueing
928 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
930 if (cfqd->busy_queues) {
931 cfq_log(cfqd, "schedule dispatch");
932 kblockd_schedule_work(&cfqd->unplug_work);
937 * Scale schedule slice based on io priority. Use the sync time slice only
938 * if a queue is marked sync and has sync io queued. A sync queue with async
939 * io only, should not get full sync slice length.
941 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
944 const int base_slice = cfqd->cfq_slice[sync];
946 WARN_ON(prio >= IOPRIO_BE_NR);
948 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
952 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
954 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
958 * cfqg_scale_charge - scale disk time charge according to cfqg weight
959 * @charge: disk time being charged
960 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
962 * Scale @charge according to @vfraction, which is in range (0, 1]. The
963 * scaling is inversely proportional.
965 * scaled = charge / vfraction
967 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
969 static inline u64 cfqg_scale_charge(unsigned long charge,
970 unsigned int vfraction)
972 u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
974 /* charge / vfraction */
975 c <<= CFQ_SERVICE_SHIFT;
976 do_div(c, vfraction);
980 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
982 s64 delta = (s64)(vdisktime - min_vdisktime);
984 min_vdisktime = vdisktime;
986 return min_vdisktime;
989 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
991 s64 delta = (s64)(vdisktime - min_vdisktime);
993 min_vdisktime = vdisktime;
995 return min_vdisktime;
998 static void update_min_vdisktime(struct cfq_rb_root *st)
1000 struct cfq_group *cfqg;
1003 cfqg = rb_entry_cfqg(st->left);
1004 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
1010 * get averaged number of queues of RT/BE priority.
1011 * average is updated, with a formula that gives more weight to higher numbers,
1012 * to quickly follows sudden increases and decrease slowly
1015 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1016 struct cfq_group *cfqg, bool rt)
1018 unsigned min_q, max_q;
1019 unsigned mult = cfq_hist_divisor - 1;
1020 unsigned round = cfq_hist_divisor / 2;
1021 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1023 min_q = min(cfqg->busy_queues_avg[rt], busy);
1024 max_q = max(cfqg->busy_queues_avg[rt], busy);
1025 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1027 return cfqg->busy_queues_avg[rt];
1030 static inline unsigned
1031 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1033 return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1036 static inline unsigned
1037 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1039 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
1040 if (cfqd->cfq_latency) {
1042 * interested queues (we consider only the ones with the same
1043 * priority class in the cfq group)
1045 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1046 cfq_class_rt(cfqq));
1047 unsigned sync_slice = cfqd->cfq_slice[1];
1048 unsigned expect_latency = sync_slice * iq;
1049 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1051 if (expect_latency > group_slice) {
1052 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
1053 /* scale low_slice according to IO priority
1054 * and sync vs async */
1055 unsigned low_slice =
1056 min(slice, base_low_slice * slice / sync_slice);
1057 /* the adapted slice value is scaled to fit all iqs
1058 * into the target latency */
1059 slice = max(slice * group_slice / expect_latency,
1067 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1069 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1071 cfqq->slice_start = jiffies;
1072 cfqq->slice_end = jiffies + slice;
1073 cfqq->allocated_slice = slice;
1074 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
1078 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1079 * isn't valid until the first request from the dispatch is activated
1080 * and the slice time set.
1082 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1084 if (cfq_cfqq_slice_new(cfqq))
1086 if (time_before(jiffies, cfqq->slice_end))
1093 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1094 * We choose the request that is closest to the head right now. Distance
1095 * behind the head is penalized and only allowed to a certain extent.
1097 static struct request *
1098 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1100 sector_t s1, s2, d1 = 0, d2 = 0;
1101 unsigned long back_max;
1102 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1103 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1104 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1106 if (rq1 == NULL || rq1 == rq2)
1111 if (rq_is_sync(rq1) != rq_is_sync(rq2))
1112 return rq_is_sync(rq1) ? rq1 : rq2;
1114 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1115 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1117 s1 = blk_rq_pos(rq1);
1118 s2 = blk_rq_pos(rq2);
1121 * by definition, 1KiB is 2 sectors
1123 back_max = cfqd->cfq_back_max * 2;
1126 * Strict one way elevator _except_ in the case where we allow
1127 * short backward seeks which are biased as twice the cost of a
1128 * similar forward seek.
1132 else if (s1 + back_max >= last)
1133 d1 = (last - s1) * cfqd->cfq_back_penalty;
1135 wrap |= CFQ_RQ1_WRAP;
1139 else if (s2 + back_max >= last)
1140 d2 = (last - s2) * cfqd->cfq_back_penalty;
1142 wrap |= CFQ_RQ2_WRAP;
1144 /* Found required data */
1147 * By doing switch() on the bit mask "wrap" we avoid having to
1148 * check two variables for all permutations: --> faster!
1151 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1167 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1170 * Since both rqs are wrapped,
1171 * start with the one that's further behind head
1172 * (--> only *one* back seek required),
1173 * since back seek takes more time than forward.
1183 * The below is leftmost cache rbtree addon
1185 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1187 /* Service tree is empty */
1192 root->left = rb_first(&root->rb);
1195 return rb_entry(root->left, struct cfq_queue, rb_node);
1200 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1203 root->left = rb_first(&root->rb);
1206 return rb_entry_cfqg(root->left);
1211 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1217 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1219 if (root->left == n)
1221 rb_erase_init(n, &root->rb);
1226 * would be nice to take fifo expire time into account as well
1228 static struct request *
1229 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1230 struct request *last)
1232 struct rb_node *rbnext = rb_next(&last->rb_node);
1233 struct rb_node *rbprev = rb_prev(&last->rb_node);
1234 struct request *next = NULL, *prev = NULL;
1236 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1239 prev = rb_entry_rq(rbprev);
1242 next = rb_entry_rq(rbnext);
1244 rbnext = rb_first(&cfqq->sort_list);
1245 if (rbnext && rbnext != &last->rb_node)
1246 next = rb_entry_rq(rbnext);
1249 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1252 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1253 struct cfq_queue *cfqq)
1256 * just an approximation, should be ok.
1258 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1259 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1263 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1265 return cfqg->vdisktime - st->min_vdisktime;
1269 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1271 struct rb_node **node = &st->rb.rb_node;
1272 struct rb_node *parent = NULL;
1273 struct cfq_group *__cfqg;
1274 s64 key = cfqg_key(st, cfqg);
1277 while (*node != NULL) {
1279 __cfqg = rb_entry_cfqg(parent);
1281 if (key < cfqg_key(st, __cfqg))
1282 node = &parent->rb_left;
1284 node = &parent->rb_right;
1290 st->left = &cfqg->rb_node;
1292 rb_link_node(&cfqg->rb_node, parent, node);
1293 rb_insert_color(&cfqg->rb_node, &st->rb);
1297 * This has to be called only on activation of cfqg
1300 cfq_update_group_weight(struct cfq_group *cfqg)
1302 if (cfqg->new_weight) {
1303 cfqg->weight = cfqg->new_weight;
1304 cfqg->new_weight = 0;
1309 cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1311 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1313 if (cfqg->new_leaf_weight) {
1314 cfqg->leaf_weight = cfqg->new_leaf_weight;
1315 cfqg->new_leaf_weight = 0;
1320 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1322 unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
1323 struct cfq_group *pos = cfqg;
1324 struct cfq_group *parent;
1327 /* add to the service tree */
1328 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1331 * Update leaf_weight. We cannot update weight at this point
1332 * because cfqg might already have been activated and is
1333 * contributing its current weight to the parent's child_weight.
1335 cfq_update_group_leaf_weight(cfqg);
1336 __cfq_group_service_tree_add(st, cfqg);
1339 * Activate @cfqg and calculate the portion of vfraction @cfqg is
1340 * entitled to. vfraction is calculated by walking the tree
1341 * towards the root calculating the fraction it has at each level.
1342 * The compounded ratio is how much vfraction @cfqg owns.
1344 * Start with the proportion tasks in this cfqg has against active
1345 * children cfqgs - its leaf_weight against children_weight.
1347 propagate = !pos->nr_active++;
1348 pos->children_weight += pos->leaf_weight;
1349 vfr = vfr * pos->leaf_weight / pos->children_weight;
1352 * Compound ->weight walking up the tree. Both activation and
1353 * vfraction calculation are done in the same loop. Propagation
1354 * stops once an already activated node is met. vfraction
1355 * calculation should always continue to the root.
1357 while ((parent = cfqg_parent(pos))) {
1359 cfq_update_group_weight(pos);
1360 propagate = !parent->nr_active++;
1361 parent->children_weight += pos->weight;
1363 vfr = vfr * pos->weight / parent->children_weight;
1367 cfqg->vfraction = max_t(unsigned, vfr, 1);
1371 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1373 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1374 struct cfq_group *__cfqg;
1378 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1382 * Currently put the group at the end. Later implement something
1383 * so that groups get lesser vtime based on their weights, so that
1384 * if group does not loose all if it was not continuously backlogged.
1386 n = rb_last(&st->rb);
1388 __cfqg = rb_entry_cfqg(n);
1389 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1391 cfqg->vdisktime = st->min_vdisktime;
1392 cfq_group_service_tree_add(st, cfqg);
1396 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1398 struct cfq_group *pos = cfqg;
1402 * Undo activation from cfq_group_service_tree_add(). Deactivate
1403 * @cfqg and propagate deactivation upwards.
1405 propagate = !--pos->nr_active;
1406 pos->children_weight -= pos->leaf_weight;
1409 struct cfq_group *parent = cfqg_parent(pos);
1411 /* @pos has 0 nr_active at this point */
1412 WARN_ON_ONCE(pos->children_weight);
1418 propagate = !--parent->nr_active;
1419 parent->children_weight -= pos->weight;
1423 /* remove from the service tree */
1424 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1425 cfq_rb_erase(&cfqg->rb_node, st);
1429 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1431 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1433 BUG_ON(cfqg->nr_cfqq < 1);
1436 /* If there are other cfq queues under this group, don't delete it */
1440 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1441 cfq_group_service_tree_del(st, cfqg);
1442 cfqg->saved_wl_slice = 0;
1443 cfqg_stats_update_dequeue(cfqg);
1446 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1447 unsigned int *unaccounted_time)
1449 unsigned int slice_used;
1452 * Queue got expired before even a single request completed or
1453 * got expired immediately after first request completion.
1455 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1457 * Also charge the seek time incurred to the group, otherwise
1458 * if there are mutiple queues in the group, each can dispatch
1459 * a single request on seeky media and cause lots of seek time
1460 * and group will never know it.
1462 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1465 slice_used = jiffies - cfqq->slice_start;
1466 if (slice_used > cfqq->allocated_slice) {
1467 *unaccounted_time = slice_used - cfqq->allocated_slice;
1468 slice_used = cfqq->allocated_slice;
1470 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1471 *unaccounted_time += cfqq->slice_start -
1472 cfqq->dispatch_start;
1478 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1479 struct cfq_queue *cfqq)
1481 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1482 unsigned int used_sl, charge, unaccounted_sl = 0;
1483 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1484 - cfqg->service_tree_idle.count;
1487 BUG_ON(nr_sync < 0);
1488 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1490 if (iops_mode(cfqd))
1491 charge = cfqq->slice_dispatch;
1492 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1493 charge = cfqq->allocated_slice;
1496 * Can't update vdisktime while on service tree and cfqg->vfraction
1497 * is valid only while on it. Cache vfr, leave the service tree,
1498 * update vdisktime and go back on. The re-addition to the tree
1499 * will also update the weights as necessary.
1501 vfr = cfqg->vfraction;
1502 cfq_group_service_tree_del(st, cfqg);
1503 cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1504 cfq_group_service_tree_add(st, cfqg);
1506 /* This group is being expired. Save the context */
1507 if (time_after(cfqd->workload_expires, jiffies)) {
1508 cfqg->saved_wl_slice = cfqd->workload_expires
1510 cfqg->saved_wl_type = cfqd->serving_wl_type;
1511 cfqg->saved_wl_class = cfqd->serving_wl_class;
1513 cfqg->saved_wl_slice = 0;
1515 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1517 cfq_log_cfqq(cfqq->cfqd, cfqq,
1518 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1519 used_sl, cfqq->slice_dispatch, charge,
1520 iops_mode(cfqd), cfqq->nr_sectors);
1521 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1522 cfqg_stats_set_start_empty_time(cfqg);
1526 * cfq_init_cfqg_base - initialize base part of a cfq_group
1527 * @cfqg: cfq_group to initialize
1529 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1530 * is enabled or not.
1532 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1534 struct cfq_rb_root *st;
1537 for_each_cfqg_st(cfqg, i, j, st)
1539 RB_CLEAR_NODE(&cfqg->rb_node);
1541 cfqg->ttime.last_end_request = jiffies;
1544 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1545 static void cfqg_stats_init(struct cfqg_stats *stats)
1547 blkg_rwstat_init(&stats->service_bytes);
1548 blkg_rwstat_init(&stats->serviced);
1549 blkg_rwstat_init(&stats->merged);
1550 blkg_rwstat_init(&stats->service_time);
1551 blkg_rwstat_init(&stats->wait_time);
1552 blkg_rwstat_init(&stats->queued);
1554 blkg_stat_init(&stats->sectors);
1555 blkg_stat_init(&stats->time);
1557 #ifdef CONFIG_DEBUG_BLK_CGROUP
1558 blkg_stat_init(&stats->unaccounted_time);
1559 blkg_stat_init(&stats->avg_queue_size_sum);
1560 blkg_stat_init(&stats->avg_queue_size_samples);
1561 blkg_stat_init(&stats->dequeue);
1562 blkg_stat_init(&stats->group_wait_time);
1563 blkg_stat_init(&stats->idle_time);
1564 blkg_stat_init(&stats->empty_time);
1568 static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1570 struct cfq_group_data *cgd;
1572 cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
1578 static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1580 struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1582 if (cpd_to_blkcg(cpd) == &blkcg_root) {
1583 cgd->weight = 2 * CFQ_WEIGHT_DEFAULT;
1584 cgd->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
1586 cgd->weight = CFQ_WEIGHT_DEFAULT;
1587 cgd->leaf_weight = CFQ_WEIGHT_DEFAULT;
1591 static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1593 kfree(cpd_to_cfqgd(cpd));
1596 static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1598 struct cfq_group *cfqg;
1600 cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1604 cfq_init_cfqg_base(cfqg);
1605 cfqg_stats_init(&cfqg->stats);
1610 static void cfq_pd_init(struct blkg_policy_data *pd)
1612 struct cfq_group *cfqg = pd_to_cfqg(pd);
1613 struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1615 cfqg->weight = cgd->weight;
1616 cfqg->leaf_weight = cgd->leaf_weight;
1619 static void cfq_pd_offline(struct blkg_policy_data *pd)
1621 struct cfq_group *cfqg = pd_to_cfqg(pd);
1624 for (i = 0; i < IOPRIO_BE_NR; i++) {
1625 if (cfqg->async_cfqq[0][i])
1626 cfq_put_queue(cfqg->async_cfqq[0][i]);
1627 if (cfqg->async_cfqq[1][i])
1628 cfq_put_queue(cfqg->async_cfqq[1][i]);
1631 if (cfqg->async_idle_cfqq)
1632 cfq_put_queue(cfqg->async_idle_cfqq);
1635 * @blkg is going offline and will be ignored by
1636 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1637 * that they don't get lost. If IOs complete after this point, the
1638 * stats for them will be lost. Oh well...
1640 cfqg_stats_xfer_dead(cfqg);
1643 static void cfq_pd_free(struct blkg_policy_data *pd)
1648 static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1650 struct cfq_group *cfqg = pd_to_cfqg(pd);
1652 cfqg_stats_reset(&cfqg->stats);
1655 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1656 struct blkcg *blkcg)
1658 struct blkcg_gq *blkg;
1660 blkg = blkg_lookup(blkcg, cfqd->queue);
1662 return blkg_to_cfqg(blkg);
1666 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1669 /* cfqq reference on cfqg */
1673 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1674 struct blkg_policy_data *pd, int off)
1676 struct cfq_group *cfqg = pd_to_cfqg(pd);
1678 if (!cfqg->dev_weight)
1680 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1683 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1685 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1686 cfqg_prfill_weight_device, &blkcg_policy_cfq,
1691 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1692 struct blkg_policy_data *pd, int off)
1694 struct cfq_group *cfqg = pd_to_cfqg(pd);
1696 if (!cfqg->dev_leaf_weight)
1698 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1701 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1703 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1704 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1709 static int cfq_print_weight(struct seq_file *sf, void *v)
1711 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1712 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1713 unsigned int val = 0;
1718 seq_printf(sf, "%u\n", val);
1722 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1724 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1725 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1726 unsigned int val = 0;
1729 val = cgd->leaf_weight;
1731 seq_printf(sf, "%u\n", val);
1735 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1736 char *buf, size_t nbytes, loff_t off,
1737 bool is_leaf_weight)
1739 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1740 struct blkg_conf_ctx ctx;
1741 struct cfq_group *cfqg;
1742 struct cfq_group_data *cfqgd;
1745 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1750 cfqg = blkg_to_cfqg(ctx.blkg);
1751 cfqgd = blkcg_to_cfqgd(blkcg);
1752 if (!cfqg || !cfqgd)
1755 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1756 if (!is_leaf_weight) {
1757 cfqg->dev_weight = ctx.v;
1758 cfqg->new_weight = ctx.v ?: cfqgd->weight;
1760 cfqg->dev_leaf_weight = ctx.v;
1761 cfqg->new_leaf_weight = ctx.v ?: cfqgd->leaf_weight;
1767 blkg_conf_finish(&ctx);
1768 return ret ?: nbytes;
1771 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1772 char *buf, size_t nbytes, loff_t off)
1774 return __cfqg_set_weight_device(of, buf, nbytes, off, false);
1777 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1778 char *buf, size_t nbytes, loff_t off)
1780 return __cfqg_set_weight_device(of, buf, nbytes, off, true);
1783 static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1784 u64 val, bool is_leaf_weight)
1786 struct blkcg *blkcg = css_to_blkcg(css);
1787 struct blkcg_gq *blkg;
1788 struct cfq_group_data *cfqgd;
1791 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1794 spin_lock_irq(&blkcg->lock);
1795 cfqgd = blkcg_to_cfqgd(blkcg);
1801 if (!is_leaf_weight)
1802 cfqgd->weight = val;
1804 cfqgd->leaf_weight = val;
1806 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1807 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1812 if (!is_leaf_weight) {
1813 if (!cfqg->dev_weight)
1814 cfqg->new_weight = cfqgd->weight;
1816 if (!cfqg->dev_leaf_weight)
1817 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1822 spin_unlock_irq(&blkcg->lock);
1826 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1829 return __cfq_set_weight(css, cft, val, false);
1832 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1833 struct cftype *cft, u64 val)
1835 return __cfq_set_weight(css, cft, val, true);
1838 static int cfqg_print_stat(struct seq_file *sf, void *v)
1840 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1841 &blkcg_policy_cfq, seq_cft(sf)->private, false);
1845 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1847 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1848 &blkcg_policy_cfq, seq_cft(sf)->private, true);
1852 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1853 struct blkg_policy_data *pd, int off)
1855 u64 sum = blkg_stat_recursive_sum(pd, off);
1857 return __blkg_prfill_u64(sf, pd, sum);
1860 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1861 struct blkg_policy_data *pd, int off)
1863 struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd, off);
1865 return __blkg_prfill_rwstat(sf, pd, &sum);
1868 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1870 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1871 cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1872 seq_cft(sf)->private, false);
1876 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1878 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1879 cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1880 seq_cft(sf)->private, true);
1884 #ifdef CONFIG_DEBUG_BLK_CGROUP
1885 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1886 struct blkg_policy_data *pd, int off)
1888 struct cfq_group *cfqg = pd_to_cfqg(pd);
1889 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1893 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1894 v = div64_u64(v, samples);
1896 __blkg_prfill_u64(sf, pd, v);
1900 /* print avg_queue_size */
1901 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1903 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1904 cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1908 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1910 static struct cftype cfq_blkcg_files[] = {
1911 /* on root, weight is mapped to leaf_weight */
1913 .name = "weight_device",
1914 .flags = CFTYPE_ONLY_ON_ROOT,
1915 .seq_show = cfqg_print_leaf_weight_device,
1916 .write = cfqg_set_leaf_weight_device,
1920 .flags = CFTYPE_ONLY_ON_ROOT,
1921 .seq_show = cfq_print_leaf_weight,
1922 .write_u64 = cfq_set_leaf_weight,
1925 /* no such mapping necessary for !roots */
1927 .name = "weight_device",
1928 .flags = CFTYPE_NOT_ON_ROOT,
1929 .seq_show = cfqg_print_weight_device,
1930 .write = cfqg_set_weight_device,
1934 .flags = CFTYPE_NOT_ON_ROOT,
1935 .seq_show = cfq_print_weight,
1936 .write_u64 = cfq_set_weight,
1940 .name = "leaf_weight_device",
1941 .seq_show = cfqg_print_leaf_weight_device,
1942 .write = cfqg_set_leaf_weight_device,
1945 .name = "leaf_weight",
1946 .seq_show = cfq_print_leaf_weight,
1947 .write_u64 = cfq_set_leaf_weight,
1950 /* statistics, covers only the tasks in the cfqg */
1953 .private = offsetof(struct cfq_group, stats.time),
1954 .seq_show = cfqg_print_stat,
1958 .private = offsetof(struct cfq_group, stats.sectors),
1959 .seq_show = cfqg_print_stat,
1962 .name = "io_service_bytes",
1963 .private = offsetof(struct cfq_group, stats.service_bytes),
1964 .seq_show = cfqg_print_rwstat,
1967 .name = "io_serviced",
1968 .private = offsetof(struct cfq_group, stats.serviced),
1969 .seq_show = cfqg_print_rwstat,
1972 .name = "io_service_time",
1973 .private = offsetof(struct cfq_group, stats.service_time),
1974 .seq_show = cfqg_print_rwstat,
1977 .name = "io_wait_time",
1978 .private = offsetof(struct cfq_group, stats.wait_time),
1979 .seq_show = cfqg_print_rwstat,
1982 .name = "io_merged",
1983 .private = offsetof(struct cfq_group, stats.merged),
1984 .seq_show = cfqg_print_rwstat,
1987 .name = "io_queued",
1988 .private = offsetof(struct cfq_group, stats.queued),
1989 .seq_show = cfqg_print_rwstat,
1992 /* the same statictics which cover the cfqg and its descendants */
1994 .name = "time_recursive",
1995 .private = offsetof(struct cfq_group, stats.time),
1996 .seq_show = cfqg_print_stat_recursive,
1999 .name = "sectors_recursive",
2000 .private = offsetof(struct cfq_group, stats.sectors),
2001 .seq_show = cfqg_print_stat_recursive,
2004 .name = "io_service_bytes_recursive",
2005 .private = offsetof(struct cfq_group, stats.service_bytes),
2006 .seq_show = cfqg_print_rwstat_recursive,
2009 .name = "io_serviced_recursive",
2010 .private = offsetof(struct cfq_group, stats.serviced),
2011 .seq_show = cfqg_print_rwstat_recursive,
2014 .name = "io_service_time_recursive",
2015 .private = offsetof(struct cfq_group, stats.service_time),
2016 .seq_show = cfqg_print_rwstat_recursive,
2019 .name = "io_wait_time_recursive",
2020 .private = offsetof(struct cfq_group, stats.wait_time),
2021 .seq_show = cfqg_print_rwstat_recursive,
2024 .name = "io_merged_recursive",
2025 .private = offsetof(struct cfq_group, stats.merged),
2026 .seq_show = cfqg_print_rwstat_recursive,
2029 .name = "io_queued_recursive",
2030 .private = offsetof(struct cfq_group, stats.queued),
2031 .seq_show = cfqg_print_rwstat_recursive,
2033 #ifdef CONFIG_DEBUG_BLK_CGROUP
2035 .name = "avg_queue_size",
2036 .seq_show = cfqg_print_avg_queue_size,
2039 .name = "group_wait_time",
2040 .private = offsetof(struct cfq_group, stats.group_wait_time),
2041 .seq_show = cfqg_print_stat,
2044 .name = "idle_time",
2045 .private = offsetof(struct cfq_group, stats.idle_time),
2046 .seq_show = cfqg_print_stat,
2049 .name = "empty_time",
2050 .private = offsetof(struct cfq_group, stats.empty_time),
2051 .seq_show = cfqg_print_stat,
2055 .private = offsetof(struct cfq_group, stats.dequeue),
2056 .seq_show = cfqg_print_stat,
2059 .name = "unaccounted_time",
2060 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2061 .seq_show = cfqg_print_stat,
2063 #endif /* CONFIG_DEBUG_BLK_CGROUP */
2066 #else /* GROUP_IOSCHED */
2067 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2068 struct blkcg *blkcg)
2070 return cfqd->root_group;
2074 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2078 #endif /* GROUP_IOSCHED */
2081 * The cfqd->service_trees holds all pending cfq_queue's that have
2082 * requests waiting to be processed. It is sorted in the order that
2083 * we will service the queues.
2085 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2088 struct rb_node **p, *parent;
2089 struct cfq_queue *__cfqq;
2090 unsigned long rb_key;
2091 struct cfq_rb_root *st;
2095 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2096 if (cfq_class_idle(cfqq)) {
2097 rb_key = CFQ_IDLE_DELAY;
2098 parent = rb_last(&st->rb);
2099 if (parent && parent != &cfqq->rb_node) {
2100 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2101 rb_key += __cfqq->rb_key;
2104 } else if (!add_front) {
2106 * Get our rb key offset. Subtract any residual slice
2107 * value carried from last service. A negative resid
2108 * count indicates slice overrun, and this should position
2109 * the next service time further away in the tree.
2111 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
2112 rb_key -= cfqq->slice_resid;
2113 cfqq->slice_resid = 0;
2116 __cfqq = cfq_rb_first(st);
2117 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
2120 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2123 * same position, nothing more to do
2125 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2128 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2129 cfqq->service_tree = NULL;
2134 cfqq->service_tree = st;
2135 p = &st->rb.rb_node;
2138 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2141 * sort by key, that represents service time.
2143 if (time_before(rb_key, __cfqq->rb_key))
2144 p = &parent->rb_left;
2146 p = &parent->rb_right;
2152 st->left = &cfqq->rb_node;
2154 cfqq->rb_key = rb_key;
2155 rb_link_node(&cfqq->rb_node, parent, p);
2156 rb_insert_color(&cfqq->rb_node, &st->rb);
2158 if (add_front || !new_cfqq)
2160 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2163 static struct cfq_queue *
2164 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2165 sector_t sector, struct rb_node **ret_parent,
2166 struct rb_node ***rb_link)
2168 struct rb_node **p, *parent;
2169 struct cfq_queue *cfqq = NULL;
2177 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2180 * Sort strictly based on sector. Smallest to the left,
2181 * largest to the right.
2183 if (sector > blk_rq_pos(cfqq->next_rq))
2184 n = &(*p)->rb_right;
2185 else if (sector < blk_rq_pos(cfqq->next_rq))
2193 *ret_parent = parent;
2199 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2201 struct rb_node **p, *parent;
2202 struct cfq_queue *__cfqq;
2205 rb_erase(&cfqq->p_node, cfqq->p_root);
2206 cfqq->p_root = NULL;
2209 if (cfq_class_idle(cfqq))
2214 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2215 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2216 blk_rq_pos(cfqq->next_rq), &parent, &p);
2218 rb_link_node(&cfqq->p_node, parent, p);
2219 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2221 cfqq->p_root = NULL;
2225 * Update cfqq's position in the service tree.
2227 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2230 * Resorting requires the cfqq to be on the RR list already.
2232 if (cfq_cfqq_on_rr(cfqq)) {
2233 cfq_service_tree_add(cfqd, cfqq, 0);
2234 cfq_prio_tree_add(cfqd, cfqq);
2239 * add to busy list of queues for service, trying to be fair in ordering
2240 * the pending list according to last request service
2242 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2244 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2245 BUG_ON(cfq_cfqq_on_rr(cfqq));
2246 cfq_mark_cfqq_on_rr(cfqq);
2247 cfqd->busy_queues++;
2248 if (cfq_cfqq_sync(cfqq))
2249 cfqd->busy_sync_queues++;
2251 cfq_resort_rr_list(cfqd, cfqq);
2255 * Called when the cfqq no longer has requests pending, remove it from
2258 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2260 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2261 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2262 cfq_clear_cfqq_on_rr(cfqq);
2264 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2265 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2266 cfqq->service_tree = NULL;
2269 rb_erase(&cfqq->p_node, cfqq->p_root);
2270 cfqq->p_root = NULL;
2273 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2274 BUG_ON(!cfqd->busy_queues);
2275 cfqd->busy_queues--;
2276 if (cfq_cfqq_sync(cfqq))
2277 cfqd->busy_sync_queues--;
2281 * rb tree support functions
2283 static void cfq_del_rq_rb(struct request *rq)
2285 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2286 const int sync = rq_is_sync(rq);
2288 BUG_ON(!cfqq->queued[sync]);
2289 cfqq->queued[sync]--;
2291 elv_rb_del(&cfqq->sort_list, rq);
2293 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2295 * Queue will be deleted from service tree when we actually
2296 * expire it later. Right now just remove it from prio tree
2300 rb_erase(&cfqq->p_node, cfqq->p_root);
2301 cfqq->p_root = NULL;
2306 static void cfq_add_rq_rb(struct request *rq)
2308 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2309 struct cfq_data *cfqd = cfqq->cfqd;
2310 struct request *prev;
2312 cfqq->queued[rq_is_sync(rq)]++;
2314 elv_rb_add(&cfqq->sort_list, rq);
2316 if (!cfq_cfqq_on_rr(cfqq))
2317 cfq_add_cfqq_rr(cfqd, cfqq);
2320 * check if this request is a better next-serve candidate
2322 prev = cfqq->next_rq;
2323 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2326 * adjust priority tree position, if ->next_rq changes
2328 if (prev != cfqq->next_rq)
2329 cfq_prio_tree_add(cfqd, cfqq);
2331 BUG_ON(!cfqq->next_rq);
2334 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2336 elv_rb_del(&cfqq->sort_list, rq);
2337 cfqq->queued[rq_is_sync(rq)]--;
2338 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2340 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2344 static struct request *
2345 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2347 struct task_struct *tsk = current;
2348 struct cfq_io_cq *cic;
2349 struct cfq_queue *cfqq;
2351 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2355 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2357 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2362 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2364 struct cfq_data *cfqd = q->elevator->elevator_data;
2366 cfqd->rq_in_driver++;
2367 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2368 cfqd->rq_in_driver);
2370 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2373 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2375 struct cfq_data *cfqd = q->elevator->elevator_data;
2377 WARN_ON(!cfqd->rq_in_driver);
2378 cfqd->rq_in_driver--;
2379 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2380 cfqd->rq_in_driver);
2383 static void cfq_remove_request(struct request *rq)
2385 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2387 if (cfqq->next_rq == rq)
2388 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2390 list_del_init(&rq->queuelist);
2393 cfqq->cfqd->rq_queued--;
2394 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2395 if (rq->cmd_flags & REQ_PRIO) {
2396 WARN_ON(!cfqq->prio_pending);
2397 cfqq->prio_pending--;
2401 static int cfq_merge(struct request_queue *q, struct request **req,
2404 struct cfq_data *cfqd = q->elevator->elevator_data;
2405 struct request *__rq;
2407 __rq = cfq_find_rq_fmerge(cfqd, bio);
2408 if (__rq && elv_rq_merge_ok(__rq, bio)) {
2410 return ELEVATOR_FRONT_MERGE;
2413 return ELEVATOR_NO_MERGE;
2416 static void cfq_merged_request(struct request_queue *q, struct request *req,
2419 if (type == ELEVATOR_FRONT_MERGE) {
2420 struct cfq_queue *cfqq = RQ_CFQQ(req);
2422 cfq_reposition_rq_rb(cfqq, req);
2426 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2429 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
2433 cfq_merged_requests(struct request_queue *q, struct request *rq,
2434 struct request *next)
2436 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2437 struct cfq_data *cfqd = q->elevator->elevator_data;
2440 * reposition in fifo if next is older than rq
2442 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2443 time_before(next->fifo_time, rq->fifo_time) &&
2444 cfqq == RQ_CFQQ(next)) {
2445 list_move(&rq->queuelist, &next->queuelist);
2446 rq->fifo_time = next->fifo_time;
2449 if (cfqq->next_rq == next)
2451 cfq_remove_request(next);
2452 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2454 cfqq = RQ_CFQQ(next);
2456 * all requests of this queue are merged to other queues, delete it
2457 * from the service tree. If it's the active_queue,
2458 * cfq_dispatch_requests() will choose to expire it or do idle
2460 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2461 cfqq != cfqd->active_queue)
2462 cfq_del_cfqq_rr(cfqd, cfqq);
2465 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
2468 struct cfq_data *cfqd = q->elevator->elevator_data;
2469 struct cfq_io_cq *cic;
2470 struct cfq_queue *cfqq;
2473 * Disallow merge of a sync bio into an async request.
2475 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2479 * Lookup the cfqq that this bio will be queued with and allow
2480 * merge only if rq is queued there.
2482 cic = cfq_cic_lookup(cfqd, current->io_context);
2486 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2487 return cfqq == RQ_CFQQ(rq);
2490 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2492 del_timer(&cfqd->idle_slice_timer);
2493 cfqg_stats_update_idle_time(cfqq->cfqg);
2496 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2497 struct cfq_queue *cfqq)
2500 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2501 cfqd->serving_wl_class, cfqd->serving_wl_type);
2502 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2503 cfqq->slice_start = 0;
2504 cfqq->dispatch_start = jiffies;
2505 cfqq->allocated_slice = 0;
2506 cfqq->slice_end = 0;
2507 cfqq->slice_dispatch = 0;
2508 cfqq->nr_sectors = 0;
2510 cfq_clear_cfqq_wait_request(cfqq);
2511 cfq_clear_cfqq_must_dispatch(cfqq);
2512 cfq_clear_cfqq_must_alloc_slice(cfqq);
2513 cfq_clear_cfqq_fifo_expire(cfqq);
2514 cfq_mark_cfqq_slice_new(cfqq);
2516 cfq_del_timer(cfqd, cfqq);
2519 cfqd->active_queue = cfqq;
2523 * current cfqq expired its slice (or was too idle), select new one
2526 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2529 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2531 if (cfq_cfqq_wait_request(cfqq))
2532 cfq_del_timer(cfqd, cfqq);
2534 cfq_clear_cfqq_wait_request(cfqq);
2535 cfq_clear_cfqq_wait_busy(cfqq);
2538 * If this cfqq is shared between multiple processes, check to
2539 * make sure that those processes are still issuing I/Os within
2540 * the mean seek distance. If not, it may be time to break the
2541 * queues apart again.
2543 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2544 cfq_mark_cfqq_split_coop(cfqq);
2547 * store what was left of this slice, if the queue idled/timed out
2550 if (cfq_cfqq_slice_new(cfqq))
2551 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2553 cfqq->slice_resid = cfqq->slice_end - jiffies;
2554 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2557 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2559 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2560 cfq_del_cfqq_rr(cfqd, cfqq);
2562 cfq_resort_rr_list(cfqd, cfqq);
2564 if (cfqq == cfqd->active_queue)
2565 cfqd->active_queue = NULL;
2567 if (cfqd->active_cic) {
2568 put_io_context(cfqd->active_cic->icq.ioc);
2569 cfqd->active_cic = NULL;
2573 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2575 struct cfq_queue *cfqq = cfqd->active_queue;
2578 __cfq_slice_expired(cfqd, cfqq, timed_out);
2582 * Get next queue for service. Unless we have a queue preemption,
2583 * we'll simply select the first cfqq in the service tree.
2585 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2587 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2588 cfqd->serving_wl_class, cfqd->serving_wl_type);
2590 if (!cfqd->rq_queued)
2593 /* There is nothing to dispatch */
2596 if (RB_EMPTY_ROOT(&st->rb))
2598 return cfq_rb_first(st);
2601 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2603 struct cfq_group *cfqg;
2604 struct cfq_queue *cfqq;
2606 struct cfq_rb_root *st;
2608 if (!cfqd->rq_queued)
2611 cfqg = cfq_get_next_cfqg(cfqd);
2615 for_each_cfqg_st(cfqg, i, j, st)
2616 if ((cfqq = cfq_rb_first(st)) != NULL)
2622 * Get and set a new active queue for service.
2624 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2625 struct cfq_queue *cfqq)
2628 cfqq = cfq_get_next_queue(cfqd);
2630 __cfq_set_active_queue(cfqd, cfqq);
2634 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2637 if (blk_rq_pos(rq) >= cfqd->last_position)
2638 return blk_rq_pos(rq) - cfqd->last_position;
2640 return cfqd->last_position - blk_rq_pos(rq);
2643 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2646 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2649 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2650 struct cfq_queue *cur_cfqq)
2652 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2653 struct rb_node *parent, *node;
2654 struct cfq_queue *__cfqq;
2655 sector_t sector = cfqd->last_position;
2657 if (RB_EMPTY_ROOT(root))
2661 * First, if we find a request starting at the end of the last
2662 * request, choose it.
2664 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2669 * If the exact sector wasn't found, the parent of the NULL leaf
2670 * will contain the closest sector.
2672 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2673 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2676 if (blk_rq_pos(__cfqq->next_rq) < sector)
2677 node = rb_next(&__cfqq->p_node);
2679 node = rb_prev(&__cfqq->p_node);
2683 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2684 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2692 * cur_cfqq - passed in so that we don't decide that the current queue is
2693 * closely cooperating with itself.
2695 * So, basically we're assuming that that cur_cfqq has dispatched at least
2696 * one request, and that cfqd->last_position reflects a position on the disk
2697 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2700 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2701 struct cfq_queue *cur_cfqq)
2703 struct cfq_queue *cfqq;
2705 if (cfq_class_idle(cur_cfqq))
2707 if (!cfq_cfqq_sync(cur_cfqq))
2709 if (CFQQ_SEEKY(cur_cfqq))
2713 * Don't search priority tree if it's the only queue in the group.
2715 if (cur_cfqq->cfqg->nr_cfqq == 1)
2719 * We should notice if some of the queues are cooperating, eg
2720 * working closely on the same area of the disk. In that case,
2721 * we can group them together and don't waste time idling.
2723 cfqq = cfqq_close(cfqd, cur_cfqq);
2727 /* If new queue belongs to different cfq_group, don't choose it */
2728 if (cur_cfqq->cfqg != cfqq->cfqg)
2732 * It only makes sense to merge sync queues.
2734 if (!cfq_cfqq_sync(cfqq))
2736 if (CFQQ_SEEKY(cfqq))
2740 * Do not merge queues of different priority classes
2742 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2749 * Determine whether we should enforce idle window for this queue.
2752 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2754 enum wl_class_t wl_class = cfqq_class(cfqq);
2755 struct cfq_rb_root *st = cfqq->service_tree;
2760 if (!cfqd->cfq_slice_idle)
2763 /* We never do for idle class queues. */
2764 if (wl_class == IDLE_WORKLOAD)
2767 /* We do for queues that were marked with idle window flag. */
2768 if (cfq_cfqq_idle_window(cfqq) &&
2769 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2773 * Otherwise, we do only if they are the last ones
2774 * in their service tree.
2776 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2777 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2779 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2783 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2785 struct cfq_queue *cfqq = cfqd->active_queue;
2786 struct cfq_io_cq *cic;
2787 unsigned long sl, group_idle = 0;
2790 * SSD device without seek penalty, disable idling. But only do so
2791 * for devices that support queuing, otherwise we still have a problem
2792 * with sync vs async workloads.
2794 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2797 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2798 WARN_ON(cfq_cfqq_slice_new(cfqq));
2801 * idle is disabled, either manually or by past process history
2803 if (!cfq_should_idle(cfqd, cfqq)) {
2804 /* no queue idling. Check for group idling */
2805 if (cfqd->cfq_group_idle)
2806 group_idle = cfqd->cfq_group_idle;
2812 * still active requests from this queue, don't idle
2814 if (cfqq->dispatched)
2818 * task has exited, don't wait
2820 cic = cfqd->active_cic;
2821 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2825 * If our average think time is larger than the remaining time
2826 * slice, then don't idle. This avoids overrunning the allotted
2829 if (sample_valid(cic->ttime.ttime_samples) &&
2830 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2831 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2832 cic->ttime.ttime_mean);
2836 /* There are other queues in the group, don't do group idle */
2837 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2840 cfq_mark_cfqq_wait_request(cfqq);
2843 sl = cfqd->cfq_group_idle;
2845 sl = cfqd->cfq_slice_idle;
2847 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2848 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2849 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2850 group_idle ? 1 : 0);
2854 * Move request from internal lists to the request queue dispatch list.
2856 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2858 struct cfq_data *cfqd = q->elevator->elevator_data;
2859 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2861 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2863 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2864 cfq_remove_request(rq);
2866 (RQ_CFQG(rq))->dispatched++;
2867 elv_dispatch_sort(q, rq);
2869 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2870 cfqq->nr_sectors += blk_rq_sectors(rq);
2871 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2875 * return expired entry, or NULL to just start from scratch in rbtree
2877 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2879 struct request *rq = NULL;
2881 if (cfq_cfqq_fifo_expire(cfqq))
2884 cfq_mark_cfqq_fifo_expire(cfqq);
2886 if (list_empty(&cfqq->fifo))
2889 rq = rq_entry_fifo(cfqq->fifo.next);
2890 if (time_before(jiffies, rq->fifo_time))
2893 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2898 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2900 const int base_rq = cfqd->cfq_slice_async_rq;
2902 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2904 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2908 * Must be called with the queue_lock held.
2910 static int cfqq_process_refs(struct cfq_queue *cfqq)
2912 int process_refs, io_refs;
2914 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2915 process_refs = cfqq->ref - io_refs;
2916 BUG_ON(process_refs < 0);
2917 return process_refs;
2920 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2922 int process_refs, new_process_refs;
2923 struct cfq_queue *__cfqq;
2926 * If there are no process references on the new_cfqq, then it is
2927 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2928 * chain may have dropped their last reference (not just their
2929 * last process reference).
2931 if (!cfqq_process_refs(new_cfqq))
2934 /* Avoid a circular list and skip interim queue merges */
2935 while ((__cfqq = new_cfqq->new_cfqq)) {
2941 process_refs = cfqq_process_refs(cfqq);
2942 new_process_refs = cfqq_process_refs(new_cfqq);
2944 * If the process for the cfqq has gone away, there is no
2945 * sense in merging the queues.
2947 if (process_refs == 0 || new_process_refs == 0)
2951 * Merge in the direction of the lesser amount of work.
2953 if (new_process_refs >= process_refs) {
2954 cfqq->new_cfqq = new_cfqq;
2955 new_cfqq->ref += process_refs;
2957 new_cfqq->new_cfqq = cfqq;
2958 cfqq->ref += new_process_refs;
2962 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2963 struct cfq_group *cfqg, enum wl_class_t wl_class)
2965 struct cfq_queue *queue;
2967 bool key_valid = false;
2968 unsigned long lowest_key = 0;
2969 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2971 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2972 /* select the one with lowest rb_key */
2973 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
2975 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2976 lowest_key = queue->rb_key;
2986 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
2990 struct cfq_rb_root *st;
2991 unsigned group_slice;
2992 enum wl_class_t original_class = cfqd->serving_wl_class;
2994 /* Choose next priority. RT > BE > IDLE */
2995 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2996 cfqd->serving_wl_class = RT_WORKLOAD;
2997 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2998 cfqd->serving_wl_class = BE_WORKLOAD;
3000 cfqd->serving_wl_class = IDLE_WORKLOAD;
3001 cfqd->workload_expires = jiffies + 1;
3005 if (original_class != cfqd->serving_wl_class)
3009 * For RT and BE, we have to choose also the type
3010 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3013 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3017 * check workload expiration, and that we still have other queues ready
3019 if (count && !time_after(jiffies, cfqd->workload_expires))
3023 /* otherwise select new workload type */
3024 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3025 cfqd->serving_wl_class);
3026 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3030 * the workload slice is computed as a fraction of target latency
3031 * proportional to the number of queues in that workload, over
3032 * all the queues in the same priority class
3034 group_slice = cfq_group_slice(cfqd, cfqg);
3036 slice = group_slice * count /
3037 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3038 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3041 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3045 * Async queues are currently system wide. Just taking
3046 * proportion of queues with-in same group will lead to higher
3047 * async ratio system wide as generally root group is going
3048 * to have higher weight. A more accurate thing would be to
3049 * calculate system wide asnc/sync ratio.
3051 tmp = cfqd->cfq_target_latency *
3052 cfqg_busy_async_queues(cfqd, cfqg);
3053 tmp = tmp/cfqd->busy_queues;
3054 slice = min_t(unsigned, slice, tmp);
3056 /* async workload slice is scaled down according to
3057 * the sync/async slice ratio. */
3058 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
3060 /* sync workload slice is at least 2 * cfq_slice_idle */
3061 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3063 slice = max_t(unsigned, slice, CFQ_MIN_TT);
3064 cfq_log(cfqd, "workload slice:%d", slice);
3065 cfqd->workload_expires = jiffies + slice;
3068 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3070 struct cfq_rb_root *st = &cfqd->grp_service_tree;
3071 struct cfq_group *cfqg;
3073 if (RB_EMPTY_ROOT(&st->rb))
3075 cfqg = cfq_rb_first_group(st);
3076 update_min_vdisktime(st);
3080 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3082 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3084 cfqd->serving_group = cfqg;
3086 /* Restore the workload type data */
3087 if (cfqg->saved_wl_slice) {
3088 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
3089 cfqd->serving_wl_type = cfqg->saved_wl_type;
3090 cfqd->serving_wl_class = cfqg->saved_wl_class;
3092 cfqd->workload_expires = jiffies - 1;
3094 choose_wl_class_and_type(cfqd, cfqg);
3098 * Select a queue for service. If we have a current active queue,
3099 * check whether to continue servicing it, or retrieve and set a new one.
3101 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3103 struct cfq_queue *cfqq, *new_cfqq = NULL;
3105 cfqq = cfqd->active_queue;
3109 if (!cfqd->rq_queued)
3113 * We were waiting for group to get backlogged. Expire the queue
3115 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3119 * The active queue has run out of time, expire it and select new.
3121 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3123 * If slice had not expired at the completion of last request
3124 * we might not have turned on wait_busy flag. Don't expire
3125 * the queue yet. Allow the group to get backlogged.
3127 * The very fact that we have used the slice, that means we
3128 * have been idling all along on this queue and it should be
3129 * ok to wait for this request to complete.
3131 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3132 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3136 goto check_group_idle;
3140 * The active queue has requests and isn't expired, allow it to
3143 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3147 * If another queue has a request waiting within our mean seek
3148 * distance, let it run. The expire code will check for close
3149 * cooperators and put the close queue at the front of the service
3150 * tree. If possible, merge the expiring queue with the new cfqq.
3152 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3154 if (!cfqq->new_cfqq)
3155 cfq_setup_merge(cfqq, new_cfqq);
3160 * No requests pending. If the active queue still has requests in
3161 * flight or is idling for a new request, allow either of these
3162 * conditions to happen (or time out) before selecting a new queue.
3164 if (timer_pending(&cfqd->idle_slice_timer)) {
3170 * This is a deep seek queue, but the device is much faster than
3171 * the queue can deliver, don't idle
3173 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3174 (cfq_cfqq_slice_new(cfqq) ||
3175 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
3176 cfq_clear_cfqq_deep(cfqq);
3177 cfq_clear_cfqq_idle_window(cfqq);
3180 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3186 * If group idle is enabled and there are requests dispatched from
3187 * this group, wait for requests to complete.
3190 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3191 cfqq->cfqg->dispatched &&
3192 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3198 cfq_slice_expired(cfqd, 0);
3201 * Current queue expired. Check if we have to switch to a new
3205 cfq_choose_cfqg(cfqd);
3207 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3212 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3216 while (cfqq->next_rq) {
3217 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3221 BUG_ON(!list_empty(&cfqq->fifo));
3223 /* By default cfqq is not expired if it is empty. Do it explicitly */
3224 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3229 * Drain our current requests. Used for barriers and when switching
3230 * io schedulers on-the-fly.
3232 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3234 struct cfq_queue *cfqq;
3237 /* Expire the timeslice of the current active queue first */
3238 cfq_slice_expired(cfqd, 0);
3239 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3240 __cfq_set_active_queue(cfqd, cfqq);
3241 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3244 BUG_ON(cfqd->busy_queues);
3246 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3250 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3251 struct cfq_queue *cfqq)
3253 /* the queue hasn't finished any request, can't estimate */
3254 if (cfq_cfqq_slice_new(cfqq))
3256 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
3263 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3265 unsigned int max_dispatch;
3268 * Drain async requests before we start sync IO
3270 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3274 * If this is an async queue and we have sync IO in flight, let it wait
3276 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3279 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3280 if (cfq_class_idle(cfqq))
3284 * Does this cfqq already have too much IO in flight?
3286 if (cfqq->dispatched >= max_dispatch) {
3287 bool promote_sync = false;
3289 * idle queue must always only have a single IO in flight
3291 if (cfq_class_idle(cfqq))
3295 * If there is only one sync queue
3296 * we can ignore async queue here and give the sync
3297 * queue no dispatch limit. The reason is a sync queue can
3298 * preempt async queue, limiting the sync queue doesn't make
3299 * sense. This is useful for aiostress test.
3301 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3302 promote_sync = true;
3305 * We have other queues, don't allow more IO from this one
3307 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3312 * Sole queue user, no limit
3314 if (cfqd->busy_queues == 1 || promote_sync)
3318 * Normally we start throttling cfqq when cfq_quantum/2
3319 * requests have been dispatched. But we can drive
3320 * deeper queue depths at the beginning of slice
3321 * subjected to upper limit of cfq_quantum.
3323 max_dispatch = cfqd->cfq_quantum;
3327 * Async queues must wait a bit before being allowed dispatch.
3328 * We also ramp up the dispatch depth gradually for async IO,
3329 * based on the last sync IO we serviced
3331 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3332 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
3335 depth = last_sync / cfqd->cfq_slice[1];
3336 if (!depth && !cfqq->dispatched)
3338 if (depth < max_dispatch)
3339 max_dispatch = depth;
3343 * If we're below the current max, allow a dispatch
3345 return cfqq->dispatched < max_dispatch;
3349 * Dispatch a request from cfqq, moving them to the request queue
3352 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3356 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3358 if (!cfq_may_dispatch(cfqd, cfqq))
3362 * follow expired path, else get first next available
3364 rq = cfq_check_fifo(cfqq);
3369 * insert request into driver dispatch list
3371 cfq_dispatch_insert(cfqd->queue, rq);
3373 if (!cfqd->active_cic) {
3374 struct cfq_io_cq *cic = RQ_CIC(rq);
3376 atomic_long_inc(&cic->icq.ioc->refcount);
3377 cfqd->active_cic = cic;
3384 * Find the cfqq that we need to service and move a request from that to the
3387 static int cfq_dispatch_requests(struct request_queue *q, int force)
3389 struct cfq_data *cfqd = q->elevator->elevator_data;
3390 struct cfq_queue *cfqq;
3392 if (!cfqd->busy_queues)
3395 if (unlikely(force))
3396 return cfq_forced_dispatch(cfqd);
3398 cfqq = cfq_select_queue(cfqd);
3403 * Dispatch a request from this cfqq, if it is allowed
3405 if (!cfq_dispatch_request(cfqd, cfqq))
3408 cfqq->slice_dispatch++;
3409 cfq_clear_cfqq_must_dispatch(cfqq);
3412 * expire an async queue immediately if it has used up its slice. idle
3413 * queue always expire after 1 dispatch round.
3415 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3416 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3417 cfq_class_idle(cfqq))) {
3418 cfqq->slice_end = jiffies + 1;
3419 cfq_slice_expired(cfqd, 0);
3422 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3427 * task holds one reference to the queue, dropped when task exits. each rq
3428 * in-flight on this queue also holds a reference, dropped when rq is freed.
3430 * Each cfq queue took a reference on the parent group. Drop it now.
3431 * queue lock must be held here.
3433 static void cfq_put_queue(struct cfq_queue *cfqq)
3435 struct cfq_data *cfqd = cfqq->cfqd;
3436 struct cfq_group *cfqg;
3438 BUG_ON(cfqq->ref <= 0);
3444 cfq_log_cfqq(cfqd, cfqq, "put_queue");
3445 BUG_ON(rb_first(&cfqq->sort_list));
3446 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3449 if (unlikely(cfqd->active_queue == cfqq)) {
3450 __cfq_slice_expired(cfqd, cfqq, 0);
3451 cfq_schedule_dispatch(cfqd);
3454 BUG_ON(cfq_cfqq_on_rr(cfqq));
3455 kmem_cache_free(cfq_pool, cfqq);
3459 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3461 struct cfq_queue *__cfqq, *next;
3464 * If this queue was scheduled to merge with another queue, be
3465 * sure to drop the reference taken on that queue (and others in
3466 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3468 __cfqq = cfqq->new_cfqq;
3470 if (__cfqq == cfqq) {
3471 WARN(1, "cfqq->new_cfqq loop detected\n");
3474 next = __cfqq->new_cfqq;
3475 cfq_put_queue(__cfqq);
3480 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3482 if (unlikely(cfqq == cfqd->active_queue)) {
3483 __cfq_slice_expired(cfqd, cfqq, 0);
3484 cfq_schedule_dispatch(cfqd);
3487 cfq_put_cooperator(cfqq);
3489 cfq_put_queue(cfqq);
3492 static void cfq_init_icq(struct io_cq *icq)
3494 struct cfq_io_cq *cic = icq_to_cic(icq);
3496 cic->ttime.last_end_request = jiffies;
3499 static void cfq_exit_icq(struct io_cq *icq)
3501 struct cfq_io_cq *cic = icq_to_cic(icq);
3502 struct cfq_data *cfqd = cic_to_cfqd(cic);
3504 if (cic_to_cfqq(cic, false)) {
3505 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3506 cic_set_cfqq(cic, NULL, false);
3509 if (cic_to_cfqq(cic, true)) {
3510 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3511 cic_set_cfqq(cic, NULL, true);
3515 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3517 struct task_struct *tsk = current;
3520 if (!cfq_cfqq_prio_changed(cfqq))
3523 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3524 switch (ioprio_class) {
3526 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3527 case IOPRIO_CLASS_NONE:
3529 * no prio set, inherit CPU scheduling settings
3531 cfqq->ioprio = task_nice_ioprio(tsk);
3532 cfqq->ioprio_class = task_nice_ioclass(tsk);
3534 case IOPRIO_CLASS_RT:
3535 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3536 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3538 case IOPRIO_CLASS_BE:
3539 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3540 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3542 case IOPRIO_CLASS_IDLE:
3543 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3545 cfq_clear_cfqq_idle_window(cfqq);
3550 * keep track of original prio settings in case we have to temporarily
3551 * elevate the priority of this queue
3553 cfqq->org_ioprio = cfqq->ioprio;
3554 cfq_clear_cfqq_prio_changed(cfqq);
3557 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3559 int ioprio = cic->icq.ioc->ioprio;
3560 struct cfq_data *cfqd = cic_to_cfqd(cic);
3561 struct cfq_queue *cfqq;
3564 * Check whether ioprio has changed. The condition may trigger
3565 * spuriously on a newly created cic but there's no harm.
3567 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3570 cfqq = cic_to_cfqq(cic, false);
3572 cfq_put_queue(cfqq);
3573 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3574 cic_set_cfqq(cic, cfqq, false);
3577 cfqq = cic_to_cfqq(cic, true);
3579 cfq_mark_cfqq_prio_changed(cfqq);
3581 cic->ioprio = ioprio;
3584 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3585 pid_t pid, bool is_sync)
3587 RB_CLEAR_NODE(&cfqq->rb_node);
3588 RB_CLEAR_NODE(&cfqq->p_node);
3589 INIT_LIST_HEAD(&cfqq->fifo);
3594 cfq_mark_cfqq_prio_changed(cfqq);
3597 if (!cfq_class_idle(cfqq))
3598 cfq_mark_cfqq_idle_window(cfqq);
3599 cfq_mark_cfqq_sync(cfqq);
3604 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3605 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3607 struct cfq_data *cfqd = cic_to_cfqd(cic);
3608 struct cfq_queue *cfqq;
3612 serial_nr = bio_blkcg(bio)->css.serial_nr;
3616 * Check whether blkcg has changed. The condition may trigger
3617 * spuriously on a newly created cic but there's no harm.
3619 if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3623 * Drop reference to queues. New queues will be assigned in new
3624 * group upon arrival of fresh requests.
3626 cfqq = cic_to_cfqq(cic, false);
3628 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3629 cic_set_cfqq(cic, NULL, false);
3630 cfq_put_queue(cfqq);
3633 cfqq = cic_to_cfqq(cic, true);
3635 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3636 cic_set_cfqq(cic, NULL, true);
3637 cfq_put_queue(cfqq);
3640 cic->blkcg_serial_nr = serial_nr;
3643 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3644 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3646 static struct cfq_queue **
3647 cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3649 switch (ioprio_class) {
3650 case IOPRIO_CLASS_RT:
3651 return &cfqg->async_cfqq[0][ioprio];
3652 case IOPRIO_CLASS_NONE:
3653 ioprio = IOPRIO_NORM;
3655 case IOPRIO_CLASS_BE:
3656 return &cfqg->async_cfqq[1][ioprio];
3657 case IOPRIO_CLASS_IDLE:
3658 return &cfqg->async_idle_cfqq;
3664 static struct cfq_queue *
3665 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3668 int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3669 int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3670 struct cfq_queue **async_cfqq = NULL;
3671 struct cfq_queue *cfqq;
3672 struct cfq_group *cfqg;
3675 cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3677 cfqq = &cfqd->oom_cfqq;
3682 if (!ioprio_valid(cic->ioprio)) {
3683 struct task_struct *tsk = current;
3684 ioprio = task_nice_ioprio(tsk);
3685 ioprio_class = task_nice_ioclass(tsk);
3687 async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3693 cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
3696 cfqq = &cfqd->oom_cfqq;
3700 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3701 cfq_init_prio_data(cfqq, cic);
3702 cfq_link_cfqq_cfqg(cfqq, cfqg);
3703 cfq_log_cfqq(cfqd, cfqq, "alloced");
3706 /* a new async queue is created, pin and remember */
3717 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3719 unsigned long elapsed = jiffies - ttime->last_end_request;
3720 elapsed = min(elapsed, 2UL * slice_idle);
3722 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3723 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3724 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3728 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3729 struct cfq_io_cq *cic)
3731 if (cfq_cfqq_sync(cfqq)) {
3732 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3733 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3734 cfqd->cfq_slice_idle);
3736 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3737 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3742 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3746 sector_t n_sec = blk_rq_sectors(rq);
3747 if (cfqq->last_request_pos) {
3748 if (cfqq->last_request_pos < blk_rq_pos(rq))
3749 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3751 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3754 cfqq->seek_history <<= 1;
3755 if (blk_queue_nonrot(cfqd->queue))
3756 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3758 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3762 * Disable idle window if the process thinks too long or seeks so much that
3766 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3767 struct cfq_io_cq *cic)
3769 int old_idle, enable_idle;
3772 * Don't idle for async or idle io prio class
3774 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3777 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3779 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3780 cfq_mark_cfqq_deep(cfqq);
3782 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3784 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3785 !cfqd->cfq_slice_idle ||
3786 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3788 else if (sample_valid(cic->ttime.ttime_samples)) {
3789 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3795 if (old_idle != enable_idle) {
3796 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3798 cfq_mark_cfqq_idle_window(cfqq);
3800 cfq_clear_cfqq_idle_window(cfqq);
3805 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3806 * no or if we aren't sure, a 1 will cause a preempt.
3809 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3812 struct cfq_queue *cfqq;
3814 cfqq = cfqd->active_queue;
3818 if (cfq_class_idle(new_cfqq))
3821 if (cfq_class_idle(cfqq))
3825 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3827 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3831 * if the new request is sync, but the currently running queue is
3832 * not, let the sync request have priority.
3834 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3837 if (new_cfqq->cfqg != cfqq->cfqg)
3840 if (cfq_slice_used(cfqq))
3843 /* Allow preemption only if we are idling on sync-noidle tree */
3844 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3845 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3846 new_cfqq->service_tree->count == 2 &&
3847 RB_EMPTY_ROOT(&cfqq->sort_list))
3851 * So both queues are sync. Let the new request get disk time if
3852 * it's a metadata request and the current queue is doing regular IO.
3854 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3858 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3860 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3863 /* An idle queue should not be idle now for some reason */
3864 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3867 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3871 * if this request is as-good as one we would expect from the
3872 * current cfqq, let it preempt
3874 if (cfq_rq_close(cfqd, cfqq, rq))
3881 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3882 * let it have half of its nominal slice.
3884 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3886 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3888 cfq_log_cfqq(cfqd, cfqq, "preempt");
3889 cfq_slice_expired(cfqd, 1);
3892 * workload type is changed, don't save slice, otherwise preempt
3895 if (old_type != cfqq_type(cfqq))
3896 cfqq->cfqg->saved_wl_slice = 0;
3899 * Put the new queue at the front of the of the current list,
3900 * so we know that it will be selected next.
3902 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3904 cfq_service_tree_add(cfqd, cfqq, 1);
3906 cfqq->slice_end = 0;
3907 cfq_mark_cfqq_slice_new(cfqq);
3911 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3912 * something we should do about it
3915 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3918 struct cfq_io_cq *cic = RQ_CIC(rq);
3921 if (rq->cmd_flags & REQ_PRIO)
3922 cfqq->prio_pending++;
3924 cfq_update_io_thinktime(cfqd, cfqq, cic);
3925 cfq_update_io_seektime(cfqd, cfqq, rq);
3926 cfq_update_idle_window(cfqd, cfqq, cic);
3928 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3930 if (cfqq == cfqd->active_queue) {
3932 * Remember that we saw a request from this process, but
3933 * don't start queuing just yet. Otherwise we risk seeing lots
3934 * of tiny requests, because we disrupt the normal plugging
3935 * and merging. If the request is already larger than a single
3936 * page, let it rip immediately. For that case we assume that
3937 * merging is already done. Ditto for a busy system that
3938 * has other work pending, don't risk delaying until the
3939 * idle timer unplug to continue working.
3941 if (cfq_cfqq_wait_request(cfqq)) {
3942 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3943 cfqd->busy_queues > 1) {
3944 cfq_del_timer(cfqd, cfqq);
3945 cfq_clear_cfqq_wait_request(cfqq);
3946 __blk_run_queue(cfqd->queue);
3948 cfqg_stats_update_idle_time(cfqq->cfqg);
3949 cfq_mark_cfqq_must_dispatch(cfqq);
3952 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3954 * not the active queue - expire current slice if it is
3955 * idle and has expired it's mean thinktime or this new queue
3956 * has some old slice time left and is of higher priority or
3957 * this new queue is RT and the current one is BE
3959 cfq_preempt_queue(cfqd, cfqq);
3960 __blk_run_queue(cfqd->queue);
3964 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3966 struct cfq_data *cfqd = q->elevator->elevator_data;
3967 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3969 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3970 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3972 rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
3973 list_add_tail(&rq->queuelist, &cfqq->fifo);
3975 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3977 cfq_rq_enqueued(cfqd, cfqq, rq);
3981 * Update hw_tag based on peak queue depth over 50 samples under
3984 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3986 struct cfq_queue *cfqq = cfqd->active_queue;
3988 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3989 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3991 if (cfqd->hw_tag == 1)
3994 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3995 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3999 * If active queue hasn't enough requests and can idle, cfq might not
4000 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4003 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4004 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4005 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4008 if (cfqd->hw_tag_samples++ < 50)
4011 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4017 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4019 struct cfq_io_cq *cic = cfqd->active_cic;
4021 /* If the queue already has requests, don't wait */
4022 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4025 /* If there are other queues in the group, don't wait */
4026 if (cfqq->cfqg->nr_cfqq > 1)
4029 /* the only queue in the group, but think time is big */
4030 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4033 if (cfq_slice_used(cfqq))
4036 /* if slice left is less than think time, wait busy */
4037 if (cic && sample_valid(cic->ttime.ttime_samples)
4038 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
4042 * If think times is less than a jiffy than ttime_mean=0 and above
4043 * will not be true. It might happen that slice has not expired yet
4044 * but will expire soon (4-5 ns) during select_queue(). To cover the
4045 * case where think time is less than a jiffy, mark the queue wait
4046 * busy if only 1 jiffy is left in the slice.
4048 if (cfqq->slice_end - jiffies == 1)
4054 static void cfq_completed_request(struct request_queue *q, struct request *rq)
4056 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4057 struct cfq_data *cfqd = cfqq->cfqd;
4058 const int sync = rq_is_sync(rq);
4062 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4063 !!(rq->cmd_flags & REQ_NOIDLE));
4065 cfq_update_hw_tag(cfqd);
4067 WARN_ON(!cfqd->rq_in_driver);
4068 WARN_ON(!cfqq->dispatched);
4069 cfqd->rq_in_driver--;
4071 (RQ_CFQG(rq))->dispatched--;
4072 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4073 rq_io_start_time_ns(rq), rq->cmd_flags);
4075 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4078 struct cfq_rb_root *st;
4080 RQ_CIC(rq)->ttime.last_end_request = now;
4082 if (cfq_cfqq_on_rr(cfqq))
4083 st = cfqq->service_tree;
4085 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4088 st->ttime.last_end_request = now;
4089 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
4090 cfqd->last_delayed_sync = now;
4093 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4094 cfqq->cfqg->ttime.last_end_request = now;
4098 * If this is the active queue, check if it needs to be expired,
4099 * or if we want to idle in case it has no pending requests.
4101 if (cfqd->active_queue == cfqq) {
4102 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4104 if (cfq_cfqq_slice_new(cfqq)) {
4105 cfq_set_prio_slice(cfqd, cfqq);
4106 cfq_clear_cfqq_slice_new(cfqq);
4110 * Should we wait for next request to come in before we expire
4113 if (cfq_should_wait_busy(cfqd, cfqq)) {
4114 unsigned long extend_sl = cfqd->cfq_slice_idle;
4115 if (!cfqd->cfq_slice_idle)
4116 extend_sl = cfqd->cfq_group_idle;
4117 cfqq->slice_end = jiffies + extend_sl;
4118 cfq_mark_cfqq_wait_busy(cfqq);
4119 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4123 * Idling is not enabled on:
4125 * - idle-priority queues
4127 * - queues with still some requests queued
4128 * - when there is a close cooperator
4130 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4131 cfq_slice_expired(cfqd, 1);
4132 else if (sync && cfqq_empty &&
4133 !cfq_close_cooperator(cfqd, cfqq)) {
4134 cfq_arm_slice_timer(cfqd);
4138 if (!cfqd->rq_in_driver)
4139 cfq_schedule_dispatch(cfqd);
4142 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4144 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4145 cfq_mark_cfqq_must_alloc_slice(cfqq);
4146 return ELV_MQUEUE_MUST;
4149 return ELV_MQUEUE_MAY;
4152 static int cfq_may_queue(struct request_queue *q, int rw)
4154 struct cfq_data *cfqd = q->elevator->elevator_data;
4155 struct task_struct *tsk = current;
4156 struct cfq_io_cq *cic;
4157 struct cfq_queue *cfqq;
4160 * don't force setup of a queue from here, as a call to may_queue
4161 * does not necessarily imply that a request actually will be queued.
4162 * so just lookup a possibly existing queue, or return 'may queue'
4165 cic = cfq_cic_lookup(cfqd, tsk->io_context);
4167 return ELV_MQUEUE_MAY;
4169 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
4171 cfq_init_prio_data(cfqq, cic);
4173 return __cfq_may_queue(cfqq);
4176 return ELV_MQUEUE_MAY;
4180 * queue lock held here
4182 static void cfq_put_request(struct request *rq)
4184 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4187 const int rw = rq_data_dir(rq);
4189 BUG_ON(!cfqq->allocated[rw]);
4190 cfqq->allocated[rw]--;
4192 /* Put down rq reference on cfqg */
4193 cfqg_put(RQ_CFQG(rq));
4194 rq->elv.priv[0] = NULL;
4195 rq->elv.priv[1] = NULL;
4197 cfq_put_queue(cfqq);
4201 static struct cfq_queue *
4202 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4203 struct cfq_queue *cfqq)
4205 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4206 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4207 cfq_mark_cfqq_coop(cfqq->new_cfqq);
4208 cfq_put_queue(cfqq);
4209 return cic_to_cfqq(cic, 1);
4213 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4214 * was the last process referring to said cfqq.
4216 static struct cfq_queue *
4217 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4219 if (cfqq_process_refs(cfqq) == 1) {
4220 cfqq->pid = current->pid;
4221 cfq_clear_cfqq_coop(cfqq);
4222 cfq_clear_cfqq_split_coop(cfqq);
4226 cic_set_cfqq(cic, NULL, 1);
4228 cfq_put_cooperator(cfqq);
4230 cfq_put_queue(cfqq);
4234 * Allocate cfq data structures associated with this request.
4237 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4240 struct cfq_data *cfqd = q->elevator->elevator_data;
4241 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4242 const int rw = rq_data_dir(rq);
4243 const bool is_sync = rq_is_sync(rq);
4244 struct cfq_queue *cfqq;
4246 spin_lock_irq(q->queue_lock);
4248 check_ioprio_changed(cic, bio);
4249 check_blkcg_changed(cic, bio);
4251 cfqq = cic_to_cfqq(cic, is_sync);
4252 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4254 cfq_put_queue(cfqq);
4255 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4256 cic_set_cfqq(cic, cfqq, is_sync);
4259 * If the queue was seeky for too long, break it apart.
4261 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4262 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4263 cfqq = split_cfqq(cic, cfqq);
4269 * Check to see if this queue is scheduled to merge with
4270 * another, closely cooperating queue. The merging of
4271 * queues happens here as it must be done in process context.
4272 * The reference on new_cfqq was taken in merge_cfqqs.
4275 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4278 cfqq->allocated[rw]++;
4281 cfqg_get(cfqq->cfqg);
4282 rq->elv.priv[0] = cfqq;
4283 rq->elv.priv[1] = cfqq->cfqg;
4284 spin_unlock_irq(q->queue_lock);
4288 static void cfq_kick_queue(struct work_struct *work)
4290 struct cfq_data *cfqd =
4291 container_of(work, struct cfq_data, unplug_work);
4292 struct request_queue *q = cfqd->queue;
4294 spin_lock_irq(q->queue_lock);
4295 __blk_run_queue(cfqd->queue);
4296 spin_unlock_irq(q->queue_lock);
4300 * Timer running if the active_queue is currently idling inside its time slice
4302 static void cfq_idle_slice_timer(unsigned long data)
4304 struct cfq_data *cfqd = (struct cfq_data *) data;
4305 struct cfq_queue *cfqq;
4306 unsigned long flags;
4309 cfq_log(cfqd, "idle timer fired");
4311 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4313 cfqq = cfqd->active_queue;
4318 * We saw a request before the queue expired, let it through
4320 if (cfq_cfqq_must_dispatch(cfqq))
4326 if (cfq_slice_used(cfqq))
4330 * only expire and reinvoke request handler, if there are
4331 * other queues with pending requests
4333 if (!cfqd->busy_queues)
4337 * not expired and it has a request pending, let it dispatch
4339 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4343 * Queue depth flag is reset only when the idle didn't succeed
4345 cfq_clear_cfqq_deep(cfqq);
4348 cfq_slice_expired(cfqd, timed_out);
4350 cfq_schedule_dispatch(cfqd);
4352 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4355 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4357 del_timer_sync(&cfqd->idle_slice_timer);
4358 cancel_work_sync(&cfqd->unplug_work);
4361 static void cfq_exit_queue(struct elevator_queue *e)
4363 struct cfq_data *cfqd = e->elevator_data;
4364 struct request_queue *q = cfqd->queue;
4366 cfq_shutdown_timer_wq(cfqd);
4368 spin_lock_irq(q->queue_lock);
4370 if (cfqd->active_queue)
4371 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4373 spin_unlock_irq(q->queue_lock);
4375 cfq_shutdown_timer_wq(cfqd);
4377 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4378 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4380 kfree(cfqd->root_group);
4385 static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4387 struct cfq_data *cfqd;
4388 struct blkcg_gq *blkg __maybe_unused;
4390 struct elevator_queue *eq;
4392 eq = elevator_alloc(q, e);
4396 cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4398 kobject_put(&eq->kobj);
4401 eq->elevator_data = cfqd;
4404 spin_lock_irq(q->queue_lock);
4406 spin_unlock_irq(q->queue_lock);
4408 /* Init root service tree */
4409 cfqd->grp_service_tree = CFQ_RB_ROOT;
4411 /* Init root group and prefer root group over other groups by default */
4412 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4413 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4417 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4420 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4421 GFP_KERNEL, cfqd->queue->node);
4422 if (!cfqd->root_group)
4425 cfq_init_cfqg_base(cfqd->root_group);
4427 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
4428 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
4431 * Not strictly needed (since RB_ROOT just clears the node and we
4432 * zeroed cfqd on alloc), but better be safe in case someone decides
4433 * to add magic to the rb code
4435 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4436 cfqd->prio_trees[i] = RB_ROOT;
4439 * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
4440 * Grab a permanent reference to it, so that the normal code flow
4441 * will not attempt to free it. oom_cfqq is linked to root_group
4442 * but shouldn't hold a reference as it'll never be unlinked. Lose
4443 * the reference from linking right away.
4445 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4446 cfqd->oom_cfqq.ref++;
4448 spin_lock_irq(q->queue_lock);
4449 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4450 cfqg_put(cfqd->root_group);
4451 spin_unlock_irq(q->queue_lock);
4453 init_timer(&cfqd->idle_slice_timer);
4454 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4455 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4457 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4459 cfqd->cfq_quantum = cfq_quantum;
4460 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4461 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4462 cfqd->cfq_back_max = cfq_back_max;
4463 cfqd->cfq_back_penalty = cfq_back_penalty;
4464 cfqd->cfq_slice[0] = cfq_slice_async;
4465 cfqd->cfq_slice[1] = cfq_slice_sync;
4466 cfqd->cfq_target_latency = cfq_target_latency;
4467 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4468 cfqd->cfq_slice_idle = cfq_slice_idle;
4469 cfqd->cfq_group_idle = cfq_group_idle;
4470 cfqd->cfq_latency = 1;
4473 * we optimistically start assuming sync ops weren't delayed in last
4474 * second, in order to have larger depth for async operations.
4476 cfqd->last_delayed_sync = jiffies - HZ;
4481 kobject_put(&eq->kobj);
4485 static void cfq_registered_queue(struct request_queue *q)
4487 struct elevator_queue *e = q->elevator;
4488 struct cfq_data *cfqd = e->elevator_data;
4491 * Default to IOPS mode with no idling for SSDs
4493 if (blk_queue_nonrot(q))
4494 cfqd->cfq_slice_idle = 0;
4498 * sysfs parts below -->
4501 cfq_var_show(unsigned int var, char *page)
4503 return sprintf(page, "%u\n", var);
4507 cfq_var_store(unsigned int *var, const char *page, size_t count)
4509 char *p = (char *) page;
4511 *var = simple_strtoul(p, &p, 10);
4515 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4516 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4518 struct cfq_data *cfqd = e->elevator_data; \
4519 unsigned int __data = __VAR; \
4521 __data = jiffies_to_msecs(__data); \
4522 return cfq_var_show(__data, (page)); \
4524 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4525 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4526 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4527 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4528 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4529 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4530 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4531 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4532 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4533 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4534 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4535 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4536 #undef SHOW_FUNCTION
4538 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4539 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4541 struct cfq_data *cfqd = e->elevator_data; \
4542 unsigned int __data; \
4543 int ret = cfq_var_store(&__data, (page), count); \
4544 if (__data < (MIN)) \
4546 else if (__data > (MAX)) \
4549 *(__PTR) = msecs_to_jiffies(__data); \
4551 *(__PTR) = __data; \
4554 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4555 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4557 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4559 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4560 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4562 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4563 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4564 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4565 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4566 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4568 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4569 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4570 #undef STORE_FUNCTION
4572 #define CFQ_ATTR(name) \
4573 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4575 static struct elv_fs_entry cfq_attrs[] = {
4577 CFQ_ATTR(fifo_expire_sync),
4578 CFQ_ATTR(fifo_expire_async),
4579 CFQ_ATTR(back_seek_max),
4580 CFQ_ATTR(back_seek_penalty),
4581 CFQ_ATTR(slice_sync),
4582 CFQ_ATTR(slice_async),
4583 CFQ_ATTR(slice_async_rq),
4584 CFQ_ATTR(slice_idle),
4585 CFQ_ATTR(group_idle),
4586 CFQ_ATTR(low_latency),
4587 CFQ_ATTR(target_latency),
4591 static struct elevator_type iosched_cfq = {
4593 .elevator_merge_fn = cfq_merge,
4594 .elevator_merged_fn = cfq_merged_request,
4595 .elevator_merge_req_fn = cfq_merged_requests,
4596 .elevator_allow_merge_fn = cfq_allow_merge,
4597 .elevator_bio_merged_fn = cfq_bio_merged,
4598 .elevator_dispatch_fn = cfq_dispatch_requests,
4599 .elevator_add_req_fn = cfq_insert_request,
4600 .elevator_activate_req_fn = cfq_activate_request,
4601 .elevator_deactivate_req_fn = cfq_deactivate_request,
4602 .elevator_completed_req_fn = cfq_completed_request,
4603 .elevator_former_req_fn = elv_rb_former_request,
4604 .elevator_latter_req_fn = elv_rb_latter_request,
4605 .elevator_init_icq_fn = cfq_init_icq,
4606 .elevator_exit_icq_fn = cfq_exit_icq,
4607 .elevator_set_req_fn = cfq_set_request,
4608 .elevator_put_req_fn = cfq_put_request,
4609 .elevator_may_queue_fn = cfq_may_queue,
4610 .elevator_init_fn = cfq_init_queue,
4611 .elevator_exit_fn = cfq_exit_queue,
4612 .elevator_registered_fn = cfq_registered_queue,
4614 .icq_size = sizeof(struct cfq_io_cq),
4615 .icq_align = __alignof__(struct cfq_io_cq),
4616 .elevator_attrs = cfq_attrs,
4617 .elevator_name = "cfq",
4618 .elevator_owner = THIS_MODULE,
4621 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4622 static struct blkcg_policy blkcg_policy_cfq = {
4623 .cftypes = cfq_blkcg_files,
4625 .cpd_alloc_fn = cfq_cpd_alloc,
4626 .cpd_init_fn = cfq_cpd_init,
4627 .cpd_free_fn = cfq_cpd_free,
4629 .pd_alloc_fn = cfq_pd_alloc,
4630 .pd_init_fn = cfq_pd_init,
4631 .pd_offline_fn = cfq_pd_offline,
4632 .pd_free_fn = cfq_pd_free,
4633 .pd_reset_stats_fn = cfq_pd_reset_stats,
4637 static int __init cfq_init(void)
4642 * could be 0 on HZ < 1000 setups
4644 if (!cfq_slice_async)
4645 cfq_slice_async = 1;
4646 if (!cfq_slice_idle)
4649 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4650 if (!cfq_group_idle)
4653 ret = blkcg_policy_register(&blkcg_policy_cfq);
4661 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4665 ret = elv_register(&iosched_cfq);
4672 kmem_cache_destroy(cfq_pool);
4674 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4675 blkcg_policy_unregister(&blkcg_policy_cfq);
4680 static void __exit cfq_exit(void)
4682 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4683 blkcg_policy_unregister(&blkcg_policy_cfq);
4685 elv_unregister(&iosched_cfq);
4686 kmem_cache_destroy(cfq_pool);
4689 module_init(cfq_init);
4690 module_exit(cfq_exit);
4692 MODULE_AUTHOR("Jens Axboe");
4693 MODULE_LICENSE("GPL");
4694 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");