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_exit(struct cfqg_stats *stats)
1547 blkg_rwstat_exit(&stats->service_bytes);
1548 blkg_rwstat_exit(&stats->serviced);
1549 blkg_rwstat_exit(&stats->merged);
1550 blkg_rwstat_exit(&stats->service_time);
1551 blkg_rwstat_exit(&stats->wait_time);
1552 blkg_rwstat_exit(&stats->queued);
1554 blkg_stat_exit(&stats->sectors);
1555 blkg_stat_exit(&stats->time);
1556 #ifdef CONFIG_DEBUG_BLK_CGROUP
1557 blkg_stat_exit(&stats->unaccounted_time);
1558 blkg_stat_exit(&stats->avg_queue_size_sum);
1559 blkg_stat_exit(&stats->avg_queue_size_samples);
1560 blkg_stat_exit(&stats->dequeue);
1561 blkg_stat_exit(&stats->group_wait_time);
1562 blkg_stat_exit(&stats->idle_time);
1563 blkg_stat_exit(&stats->empty_time);
1567 static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
1569 if (blkg_rwstat_init(&stats->service_bytes, gfp) ||
1570 blkg_rwstat_init(&stats->serviced, gfp) ||
1571 blkg_rwstat_init(&stats->merged, gfp) ||
1572 blkg_rwstat_init(&stats->service_time, gfp) ||
1573 blkg_rwstat_init(&stats->wait_time, gfp) ||
1574 blkg_rwstat_init(&stats->queued, gfp) ||
1576 blkg_stat_init(&stats->sectors, gfp) ||
1577 blkg_stat_init(&stats->time, gfp))
1580 #ifdef CONFIG_DEBUG_BLK_CGROUP
1581 if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
1582 blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
1583 blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
1584 blkg_stat_init(&stats->dequeue, gfp) ||
1585 blkg_stat_init(&stats->group_wait_time, gfp) ||
1586 blkg_stat_init(&stats->idle_time, gfp) ||
1587 blkg_stat_init(&stats->empty_time, gfp))
1592 cfqg_stats_exit(stats);
1596 static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1598 struct cfq_group_data *cgd;
1600 cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
1606 static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1608 struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1610 if (cpd_to_blkcg(cpd) == &blkcg_root) {
1611 cgd->weight = 2 * CFQ_WEIGHT_DEFAULT;
1612 cgd->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
1614 cgd->weight = CFQ_WEIGHT_DEFAULT;
1615 cgd->leaf_weight = CFQ_WEIGHT_DEFAULT;
1619 static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1621 kfree(cpd_to_cfqgd(cpd));
1624 static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1626 struct cfq_group *cfqg;
1628 cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1632 cfq_init_cfqg_base(cfqg);
1633 if (cfqg_stats_init(&cfqg->stats, gfp)) {
1641 static void cfq_pd_init(struct blkg_policy_data *pd)
1643 struct cfq_group *cfqg = pd_to_cfqg(pd);
1644 struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1646 cfqg->weight = cgd->weight;
1647 cfqg->leaf_weight = cgd->leaf_weight;
1650 static void cfq_pd_offline(struct blkg_policy_data *pd)
1652 struct cfq_group *cfqg = pd_to_cfqg(pd);
1655 for (i = 0; i < IOPRIO_BE_NR; i++) {
1656 if (cfqg->async_cfqq[0][i])
1657 cfq_put_queue(cfqg->async_cfqq[0][i]);
1658 if (cfqg->async_cfqq[1][i])
1659 cfq_put_queue(cfqg->async_cfqq[1][i]);
1662 if (cfqg->async_idle_cfqq)
1663 cfq_put_queue(cfqg->async_idle_cfqq);
1666 * @blkg is going offline and will be ignored by
1667 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1668 * that they don't get lost. If IOs complete after this point, the
1669 * stats for them will be lost. Oh well...
1671 cfqg_stats_xfer_dead(cfqg);
1674 static void cfq_pd_free(struct blkg_policy_data *pd)
1676 struct cfq_group *cfqg = pd_to_cfqg(pd);
1678 cfqg_stats_exit(&cfqg->stats);
1682 static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1684 struct cfq_group *cfqg = pd_to_cfqg(pd);
1686 cfqg_stats_reset(&cfqg->stats);
1689 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1690 struct blkcg *blkcg)
1692 struct blkcg_gq *blkg;
1694 blkg = blkg_lookup(blkcg, cfqd->queue);
1696 return blkg_to_cfqg(blkg);
1700 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1703 /* cfqq reference on cfqg */
1707 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1708 struct blkg_policy_data *pd, int off)
1710 struct cfq_group *cfqg = pd_to_cfqg(pd);
1712 if (!cfqg->dev_weight)
1714 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1717 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1719 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1720 cfqg_prfill_weight_device, &blkcg_policy_cfq,
1725 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1726 struct blkg_policy_data *pd, int off)
1728 struct cfq_group *cfqg = pd_to_cfqg(pd);
1730 if (!cfqg->dev_leaf_weight)
1732 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1735 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1737 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1738 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1743 static int cfq_print_weight(struct seq_file *sf, void *v)
1745 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1746 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1747 unsigned int val = 0;
1752 seq_printf(sf, "%u\n", val);
1756 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1758 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1759 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1760 unsigned int val = 0;
1763 val = cgd->leaf_weight;
1765 seq_printf(sf, "%u\n", val);
1769 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1770 char *buf, size_t nbytes, loff_t off,
1771 bool is_leaf_weight)
1773 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1774 struct blkg_conf_ctx ctx;
1775 struct cfq_group *cfqg;
1776 struct cfq_group_data *cfqgd;
1779 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1784 cfqg = blkg_to_cfqg(ctx.blkg);
1785 cfqgd = blkcg_to_cfqgd(blkcg);
1786 if (!cfqg || !cfqgd)
1789 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1790 if (!is_leaf_weight) {
1791 cfqg->dev_weight = ctx.v;
1792 cfqg->new_weight = ctx.v ?: cfqgd->weight;
1794 cfqg->dev_leaf_weight = ctx.v;
1795 cfqg->new_leaf_weight = ctx.v ?: cfqgd->leaf_weight;
1801 blkg_conf_finish(&ctx);
1802 return ret ?: nbytes;
1805 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1806 char *buf, size_t nbytes, loff_t off)
1808 return __cfqg_set_weight_device(of, buf, nbytes, off, false);
1811 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1812 char *buf, size_t nbytes, loff_t off)
1814 return __cfqg_set_weight_device(of, buf, nbytes, off, true);
1817 static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1818 u64 val, bool is_leaf_weight)
1820 struct blkcg *blkcg = css_to_blkcg(css);
1821 struct blkcg_gq *blkg;
1822 struct cfq_group_data *cfqgd;
1825 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1828 spin_lock_irq(&blkcg->lock);
1829 cfqgd = blkcg_to_cfqgd(blkcg);
1835 if (!is_leaf_weight)
1836 cfqgd->weight = val;
1838 cfqgd->leaf_weight = val;
1840 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1841 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1846 if (!is_leaf_weight) {
1847 if (!cfqg->dev_weight)
1848 cfqg->new_weight = cfqgd->weight;
1850 if (!cfqg->dev_leaf_weight)
1851 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1856 spin_unlock_irq(&blkcg->lock);
1860 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1863 return __cfq_set_weight(css, cft, val, false);
1866 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1867 struct cftype *cft, u64 val)
1869 return __cfq_set_weight(css, cft, val, true);
1872 static int cfqg_print_stat(struct seq_file *sf, void *v)
1874 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1875 &blkcg_policy_cfq, seq_cft(sf)->private, false);
1879 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1881 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1882 &blkcg_policy_cfq, seq_cft(sf)->private, true);
1886 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1887 struct blkg_policy_data *pd, int off)
1889 u64 sum = blkg_stat_recursive_sum(pd, off);
1891 return __blkg_prfill_u64(sf, pd, sum);
1894 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1895 struct blkg_policy_data *pd, int off)
1897 struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd, off);
1899 return __blkg_prfill_rwstat(sf, pd, &sum);
1902 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1904 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1905 cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1906 seq_cft(sf)->private, false);
1910 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1912 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1913 cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1914 seq_cft(sf)->private, true);
1918 #ifdef CONFIG_DEBUG_BLK_CGROUP
1919 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1920 struct blkg_policy_data *pd, int off)
1922 struct cfq_group *cfqg = pd_to_cfqg(pd);
1923 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1927 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1928 v = div64_u64(v, samples);
1930 __blkg_prfill_u64(sf, pd, v);
1934 /* print avg_queue_size */
1935 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1937 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1938 cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1942 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1944 static struct cftype cfq_blkcg_files[] = {
1945 /* on root, weight is mapped to leaf_weight */
1947 .name = "weight_device",
1948 .flags = CFTYPE_ONLY_ON_ROOT,
1949 .seq_show = cfqg_print_leaf_weight_device,
1950 .write = cfqg_set_leaf_weight_device,
1954 .flags = CFTYPE_ONLY_ON_ROOT,
1955 .seq_show = cfq_print_leaf_weight,
1956 .write_u64 = cfq_set_leaf_weight,
1959 /* no such mapping necessary for !roots */
1961 .name = "weight_device",
1962 .flags = CFTYPE_NOT_ON_ROOT,
1963 .seq_show = cfqg_print_weight_device,
1964 .write = cfqg_set_weight_device,
1968 .flags = CFTYPE_NOT_ON_ROOT,
1969 .seq_show = cfq_print_weight,
1970 .write_u64 = cfq_set_weight,
1974 .name = "leaf_weight_device",
1975 .seq_show = cfqg_print_leaf_weight_device,
1976 .write = cfqg_set_leaf_weight_device,
1979 .name = "leaf_weight",
1980 .seq_show = cfq_print_leaf_weight,
1981 .write_u64 = cfq_set_leaf_weight,
1984 /* statistics, covers only the tasks in the cfqg */
1987 .private = offsetof(struct cfq_group, stats.time),
1988 .seq_show = cfqg_print_stat,
1992 .private = offsetof(struct cfq_group, stats.sectors),
1993 .seq_show = cfqg_print_stat,
1996 .name = "io_service_bytes",
1997 .private = offsetof(struct cfq_group, stats.service_bytes),
1998 .seq_show = cfqg_print_rwstat,
2001 .name = "io_serviced",
2002 .private = offsetof(struct cfq_group, stats.serviced),
2003 .seq_show = cfqg_print_rwstat,
2006 .name = "io_service_time",
2007 .private = offsetof(struct cfq_group, stats.service_time),
2008 .seq_show = cfqg_print_rwstat,
2011 .name = "io_wait_time",
2012 .private = offsetof(struct cfq_group, stats.wait_time),
2013 .seq_show = cfqg_print_rwstat,
2016 .name = "io_merged",
2017 .private = offsetof(struct cfq_group, stats.merged),
2018 .seq_show = cfqg_print_rwstat,
2021 .name = "io_queued",
2022 .private = offsetof(struct cfq_group, stats.queued),
2023 .seq_show = cfqg_print_rwstat,
2026 /* the same statictics which cover the cfqg and its descendants */
2028 .name = "time_recursive",
2029 .private = offsetof(struct cfq_group, stats.time),
2030 .seq_show = cfqg_print_stat_recursive,
2033 .name = "sectors_recursive",
2034 .private = offsetof(struct cfq_group, stats.sectors),
2035 .seq_show = cfqg_print_stat_recursive,
2038 .name = "io_service_bytes_recursive",
2039 .private = offsetof(struct cfq_group, stats.service_bytes),
2040 .seq_show = cfqg_print_rwstat_recursive,
2043 .name = "io_serviced_recursive",
2044 .private = offsetof(struct cfq_group, stats.serviced),
2045 .seq_show = cfqg_print_rwstat_recursive,
2048 .name = "io_service_time_recursive",
2049 .private = offsetof(struct cfq_group, stats.service_time),
2050 .seq_show = cfqg_print_rwstat_recursive,
2053 .name = "io_wait_time_recursive",
2054 .private = offsetof(struct cfq_group, stats.wait_time),
2055 .seq_show = cfqg_print_rwstat_recursive,
2058 .name = "io_merged_recursive",
2059 .private = offsetof(struct cfq_group, stats.merged),
2060 .seq_show = cfqg_print_rwstat_recursive,
2063 .name = "io_queued_recursive",
2064 .private = offsetof(struct cfq_group, stats.queued),
2065 .seq_show = cfqg_print_rwstat_recursive,
2067 #ifdef CONFIG_DEBUG_BLK_CGROUP
2069 .name = "avg_queue_size",
2070 .seq_show = cfqg_print_avg_queue_size,
2073 .name = "group_wait_time",
2074 .private = offsetof(struct cfq_group, stats.group_wait_time),
2075 .seq_show = cfqg_print_stat,
2078 .name = "idle_time",
2079 .private = offsetof(struct cfq_group, stats.idle_time),
2080 .seq_show = cfqg_print_stat,
2083 .name = "empty_time",
2084 .private = offsetof(struct cfq_group, stats.empty_time),
2085 .seq_show = cfqg_print_stat,
2089 .private = offsetof(struct cfq_group, stats.dequeue),
2090 .seq_show = cfqg_print_stat,
2093 .name = "unaccounted_time",
2094 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2095 .seq_show = cfqg_print_stat,
2097 #endif /* CONFIG_DEBUG_BLK_CGROUP */
2100 #else /* GROUP_IOSCHED */
2101 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2102 struct blkcg *blkcg)
2104 return cfqd->root_group;
2108 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2112 #endif /* GROUP_IOSCHED */
2115 * The cfqd->service_trees holds all pending cfq_queue's that have
2116 * requests waiting to be processed. It is sorted in the order that
2117 * we will service the queues.
2119 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2122 struct rb_node **p, *parent;
2123 struct cfq_queue *__cfqq;
2124 unsigned long rb_key;
2125 struct cfq_rb_root *st;
2129 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2130 if (cfq_class_idle(cfqq)) {
2131 rb_key = CFQ_IDLE_DELAY;
2132 parent = rb_last(&st->rb);
2133 if (parent && parent != &cfqq->rb_node) {
2134 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2135 rb_key += __cfqq->rb_key;
2138 } else if (!add_front) {
2140 * Get our rb key offset. Subtract any residual slice
2141 * value carried from last service. A negative resid
2142 * count indicates slice overrun, and this should position
2143 * the next service time further away in the tree.
2145 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
2146 rb_key -= cfqq->slice_resid;
2147 cfqq->slice_resid = 0;
2150 __cfqq = cfq_rb_first(st);
2151 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
2154 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2157 * same position, nothing more to do
2159 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2162 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2163 cfqq->service_tree = NULL;
2168 cfqq->service_tree = st;
2169 p = &st->rb.rb_node;
2172 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2175 * sort by key, that represents service time.
2177 if (time_before(rb_key, __cfqq->rb_key))
2178 p = &parent->rb_left;
2180 p = &parent->rb_right;
2186 st->left = &cfqq->rb_node;
2188 cfqq->rb_key = rb_key;
2189 rb_link_node(&cfqq->rb_node, parent, p);
2190 rb_insert_color(&cfqq->rb_node, &st->rb);
2192 if (add_front || !new_cfqq)
2194 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2197 static struct cfq_queue *
2198 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2199 sector_t sector, struct rb_node **ret_parent,
2200 struct rb_node ***rb_link)
2202 struct rb_node **p, *parent;
2203 struct cfq_queue *cfqq = NULL;
2211 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2214 * Sort strictly based on sector. Smallest to the left,
2215 * largest to the right.
2217 if (sector > blk_rq_pos(cfqq->next_rq))
2218 n = &(*p)->rb_right;
2219 else if (sector < blk_rq_pos(cfqq->next_rq))
2227 *ret_parent = parent;
2233 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2235 struct rb_node **p, *parent;
2236 struct cfq_queue *__cfqq;
2239 rb_erase(&cfqq->p_node, cfqq->p_root);
2240 cfqq->p_root = NULL;
2243 if (cfq_class_idle(cfqq))
2248 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2249 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2250 blk_rq_pos(cfqq->next_rq), &parent, &p);
2252 rb_link_node(&cfqq->p_node, parent, p);
2253 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2255 cfqq->p_root = NULL;
2259 * Update cfqq's position in the service tree.
2261 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2264 * Resorting requires the cfqq to be on the RR list already.
2266 if (cfq_cfqq_on_rr(cfqq)) {
2267 cfq_service_tree_add(cfqd, cfqq, 0);
2268 cfq_prio_tree_add(cfqd, cfqq);
2273 * add to busy list of queues for service, trying to be fair in ordering
2274 * the pending list according to last request service
2276 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2278 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2279 BUG_ON(cfq_cfqq_on_rr(cfqq));
2280 cfq_mark_cfqq_on_rr(cfqq);
2281 cfqd->busy_queues++;
2282 if (cfq_cfqq_sync(cfqq))
2283 cfqd->busy_sync_queues++;
2285 cfq_resort_rr_list(cfqd, cfqq);
2289 * Called when the cfqq no longer has requests pending, remove it from
2292 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2294 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2295 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2296 cfq_clear_cfqq_on_rr(cfqq);
2298 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2299 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2300 cfqq->service_tree = NULL;
2303 rb_erase(&cfqq->p_node, cfqq->p_root);
2304 cfqq->p_root = NULL;
2307 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2308 BUG_ON(!cfqd->busy_queues);
2309 cfqd->busy_queues--;
2310 if (cfq_cfqq_sync(cfqq))
2311 cfqd->busy_sync_queues--;
2315 * rb tree support functions
2317 static void cfq_del_rq_rb(struct request *rq)
2319 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2320 const int sync = rq_is_sync(rq);
2322 BUG_ON(!cfqq->queued[sync]);
2323 cfqq->queued[sync]--;
2325 elv_rb_del(&cfqq->sort_list, rq);
2327 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2329 * Queue will be deleted from service tree when we actually
2330 * expire it later. Right now just remove it from prio tree
2334 rb_erase(&cfqq->p_node, cfqq->p_root);
2335 cfqq->p_root = NULL;
2340 static void cfq_add_rq_rb(struct request *rq)
2342 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2343 struct cfq_data *cfqd = cfqq->cfqd;
2344 struct request *prev;
2346 cfqq->queued[rq_is_sync(rq)]++;
2348 elv_rb_add(&cfqq->sort_list, rq);
2350 if (!cfq_cfqq_on_rr(cfqq))
2351 cfq_add_cfqq_rr(cfqd, cfqq);
2354 * check if this request is a better next-serve candidate
2356 prev = cfqq->next_rq;
2357 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2360 * adjust priority tree position, if ->next_rq changes
2362 if (prev != cfqq->next_rq)
2363 cfq_prio_tree_add(cfqd, cfqq);
2365 BUG_ON(!cfqq->next_rq);
2368 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2370 elv_rb_del(&cfqq->sort_list, rq);
2371 cfqq->queued[rq_is_sync(rq)]--;
2372 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2374 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2378 static struct request *
2379 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2381 struct task_struct *tsk = current;
2382 struct cfq_io_cq *cic;
2383 struct cfq_queue *cfqq;
2385 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2389 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2391 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2396 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2398 struct cfq_data *cfqd = q->elevator->elevator_data;
2400 cfqd->rq_in_driver++;
2401 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2402 cfqd->rq_in_driver);
2404 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2407 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2409 struct cfq_data *cfqd = q->elevator->elevator_data;
2411 WARN_ON(!cfqd->rq_in_driver);
2412 cfqd->rq_in_driver--;
2413 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2414 cfqd->rq_in_driver);
2417 static void cfq_remove_request(struct request *rq)
2419 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2421 if (cfqq->next_rq == rq)
2422 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2424 list_del_init(&rq->queuelist);
2427 cfqq->cfqd->rq_queued--;
2428 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2429 if (rq->cmd_flags & REQ_PRIO) {
2430 WARN_ON(!cfqq->prio_pending);
2431 cfqq->prio_pending--;
2435 static int cfq_merge(struct request_queue *q, struct request **req,
2438 struct cfq_data *cfqd = q->elevator->elevator_data;
2439 struct request *__rq;
2441 __rq = cfq_find_rq_fmerge(cfqd, bio);
2442 if (__rq && elv_rq_merge_ok(__rq, bio)) {
2444 return ELEVATOR_FRONT_MERGE;
2447 return ELEVATOR_NO_MERGE;
2450 static void cfq_merged_request(struct request_queue *q, struct request *req,
2453 if (type == ELEVATOR_FRONT_MERGE) {
2454 struct cfq_queue *cfqq = RQ_CFQQ(req);
2456 cfq_reposition_rq_rb(cfqq, req);
2460 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2463 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
2467 cfq_merged_requests(struct request_queue *q, struct request *rq,
2468 struct request *next)
2470 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2471 struct cfq_data *cfqd = q->elevator->elevator_data;
2474 * reposition in fifo if next is older than rq
2476 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2477 time_before(next->fifo_time, rq->fifo_time) &&
2478 cfqq == RQ_CFQQ(next)) {
2479 list_move(&rq->queuelist, &next->queuelist);
2480 rq->fifo_time = next->fifo_time;
2483 if (cfqq->next_rq == next)
2485 cfq_remove_request(next);
2486 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2488 cfqq = RQ_CFQQ(next);
2490 * all requests of this queue are merged to other queues, delete it
2491 * from the service tree. If it's the active_queue,
2492 * cfq_dispatch_requests() will choose to expire it or do idle
2494 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2495 cfqq != cfqd->active_queue)
2496 cfq_del_cfqq_rr(cfqd, cfqq);
2499 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
2502 struct cfq_data *cfqd = q->elevator->elevator_data;
2503 struct cfq_io_cq *cic;
2504 struct cfq_queue *cfqq;
2507 * Disallow merge of a sync bio into an async request.
2509 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2513 * Lookup the cfqq that this bio will be queued with and allow
2514 * merge only if rq is queued there.
2516 cic = cfq_cic_lookup(cfqd, current->io_context);
2520 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2521 return cfqq == RQ_CFQQ(rq);
2524 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2526 del_timer(&cfqd->idle_slice_timer);
2527 cfqg_stats_update_idle_time(cfqq->cfqg);
2530 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2531 struct cfq_queue *cfqq)
2534 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2535 cfqd->serving_wl_class, cfqd->serving_wl_type);
2536 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2537 cfqq->slice_start = 0;
2538 cfqq->dispatch_start = jiffies;
2539 cfqq->allocated_slice = 0;
2540 cfqq->slice_end = 0;
2541 cfqq->slice_dispatch = 0;
2542 cfqq->nr_sectors = 0;
2544 cfq_clear_cfqq_wait_request(cfqq);
2545 cfq_clear_cfqq_must_dispatch(cfqq);
2546 cfq_clear_cfqq_must_alloc_slice(cfqq);
2547 cfq_clear_cfqq_fifo_expire(cfqq);
2548 cfq_mark_cfqq_slice_new(cfqq);
2550 cfq_del_timer(cfqd, cfqq);
2553 cfqd->active_queue = cfqq;
2557 * current cfqq expired its slice (or was too idle), select new one
2560 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2563 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2565 if (cfq_cfqq_wait_request(cfqq))
2566 cfq_del_timer(cfqd, cfqq);
2568 cfq_clear_cfqq_wait_request(cfqq);
2569 cfq_clear_cfqq_wait_busy(cfqq);
2572 * If this cfqq is shared between multiple processes, check to
2573 * make sure that those processes are still issuing I/Os within
2574 * the mean seek distance. If not, it may be time to break the
2575 * queues apart again.
2577 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2578 cfq_mark_cfqq_split_coop(cfqq);
2581 * store what was left of this slice, if the queue idled/timed out
2584 if (cfq_cfqq_slice_new(cfqq))
2585 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2587 cfqq->slice_resid = cfqq->slice_end - jiffies;
2588 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2591 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2593 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2594 cfq_del_cfqq_rr(cfqd, cfqq);
2596 cfq_resort_rr_list(cfqd, cfqq);
2598 if (cfqq == cfqd->active_queue)
2599 cfqd->active_queue = NULL;
2601 if (cfqd->active_cic) {
2602 put_io_context(cfqd->active_cic->icq.ioc);
2603 cfqd->active_cic = NULL;
2607 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2609 struct cfq_queue *cfqq = cfqd->active_queue;
2612 __cfq_slice_expired(cfqd, cfqq, timed_out);
2616 * Get next queue for service. Unless we have a queue preemption,
2617 * we'll simply select the first cfqq in the service tree.
2619 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2621 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2622 cfqd->serving_wl_class, cfqd->serving_wl_type);
2624 if (!cfqd->rq_queued)
2627 /* There is nothing to dispatch */
2630 if (RB_EMPTY_ROOT(&st->rb))
2632 return cfq_rb_first(st);
2635 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2637 struct cfq_group *cfqg;
2638 struct cfq_queue *cfqq;
2640 struct cfq_rb_root *st;
2642 if (!cfqd->rq_queued)
2645 cfqg = cfq_get_next_cfqg(cfqd);
2649 for_each_cfqg_st(cfqg, i, j, st)
2650 if ((cfqq = cfq_rb_first(st)) != NULL)
2656 * Get and set a new active queue for service.
2658 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2659 struct cfq_queue *cfqq)
2662 cfqq = cfq_get_next_queue(cfqd);
2664 __cfq_set_active_queue(cfqd, cfqq);
2668 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2671 if (blk_rq_pos(rq) >= cfqd->last_position)
2672 return blk_rq_pos(rq) - cfqd->last_position;
2674 return cfqd->last_position - blk_rq_pos(rq);
2677 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2680 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2683 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2684 struct cfq_queue *cur_cfqq)
2686 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2687 struct rb_node *parent, *node;
2688 struct cfq_queue *__cfqq;
2689 sector_t sector = cfqd->last_position;
2691 if (RB_EMPTY_ROOT(root))
2695 * First, if we find a request starting at the end of the last
2696 * request, choose it.
2698 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2703 * If the exact sector wasn't found, the parent of the NULL leaf
2704 * will contain the closest sector.
2706 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2707 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2710 if (blk_rq_pos(__cfqq->next_rq) < sector)
2711 node = rb_next(&__cfqq->p_node);
2713 node = rb_prev(&__cfqq->p_node);
2717 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2718 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2726 * cur_cfqq - passed in so that we don't decide that the current queue is
2727 * closely cooperating with itself.
2729 * So, basically we're assuming that that cur_cfqq has dispatched at least
2730 * one request, and that cfqd->last_position reflects a position on the disk
2731 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2734 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2735 struct cfq_queue *cur_cfqq)
2737 struct cfq_queue *cfqq;
2739 if (cfq_class_idle(cur_cfqq))
2741 if (!cfq_cfqq_sync(cur_cfqq))
2743 if (CFQQ_SEEKY(cur_cfqq))
2747 * Don't search priority tree if it's the only queue in the group.
2749 if (cur_cfqq->cfqg->nr_cfqq == 1)
2753 * We should notice if some of the queues are cooperating, eg
2754 * working closely on the same area of the disk. In that case,
2755 * we can group them together and don't waste time idling.
2757 cfqq = cfqq_close(cfqd, cur_cfqq);
2761 /* If new queue belongs to different cfq_group, don't choose it */
2762 if (cur_cfqq->cfqg != cfqq->cfqg)
2766 * It only makes sense to merge sync queues.
2768 if (!cfq_cfqq_sync(cfqq))
2770 if (CFQQ_SEEKY(cfqq))
2774 * Do not merge queues of different priority classes
2776 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2783 * Determine whether we should enforce idle window for this queue.
2786 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2788 enum wl_class_t wl_class = cfqq_class(cfqq);
2789 struct cfq_rb_root *st = cfqq->service_tree;
2794 if (!cfqd->cfq_slice_idle)
2797 /* We never do for idle class queues. */
2798 if (wl_class == IDLE_WORKLOAD)
2801 /* We do for queues that were marked with idle window flag. */
2802 if (cfq_cfqq_idle_window(cfqq) &&
2803 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2807 * Otherwise, we do only if they are the last ones
2808 * in their service tree.
2810 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2811 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2813 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2817 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2819 struct cfq_queue *cfqq = cfqd->active_queue;
2820 struct cfq_io_cq *cic;
2821 unsigned long sl, group_idle = 0;
2824 * SSD device without seek penalty, disable idling. But only do so
2825 * for devices that support queuing, otherwise we still have a problem
2826 * with sync vs async workloads.
2828 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2831 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2832 WARN_ON(cfq_cfqq_slice_new(cfqq));
2835 * idle is disabled, either manually or by past process history
2837 if (!cfq_should_idle(cfqd, cfqq)) {
2838 /* no queue idling. Check for group idling */
2839 if (cfqd->cfq_group_idle)
2840 group_idle = cfqd->cfq_group_idle;
2846 * still active requests from this queue, don't idle
2848 if (cfqq->dispatched)
2852 * task has exited, don't wait
2854 cic = cfqd->active_cic;
2855 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2859 * If our average think time is larger than the remaining time
2860 * slice, then don't idle. This avoids overrunning the allotted
2863 if (sample_valid(cic->ttime.ttime_samples) &&
2864 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2865 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2866 cic->ttime.ttime_mean);
2870 /* There are other queues in the group, don't do group idle */
2871 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2874 cfq_mark_cfqq_wait_request(cfqq);
2877 sl = cfqd->cfq_group_idle;
2879 sl = cfqd->cfq_slice_idle;
2881 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2882 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2883 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2884 group_idle ? 1 : 0);
2888 * Move request from internal lists to the request queue dispatch list.
2890 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2892 struct cfq_data *cfqd = q->elevator->elevator_data;
2893 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2895 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2897 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2898 cfq_remove_request(rq);
2900 (RQ_CFQG(rq))->dispatched++;
2901 elv_dispatch_sort(q, rq);
2903 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2904 cfqq->nr_sectors += blk_rq_sectors(rq);
2905 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2909 * return expired entry, or NULL to just start from scratch in rbtree
2911 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2913 struct request *rq = NULL;
2915 if (cfq_cfqq_fifo_expire(cfqq))
2918 cfq_mark_cfqq_fifo_expire(cfqq);
2920 if (list_empty(&cfqq->fifo))
2923 rq = rq_entry_fifo(cfqq->fifo.next);
2924 if (time_before(jiffies, rq->fifo_time))
2927 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2932 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2934 const int base_rq = cfqd->cfq_slice_async_rq;
2936 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2938 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2942 * Must be called with the queue_lock held.
2944 static int cfqq_process_refs(struct cfq_queue *cfqq)
2946 int process_refs, io_refs;
2948 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2949 process_refs = cfqq->ref - io_refs;
2950 BUG_ON(process_refs < 0);
2951 return process_refs;
2954 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2956 int process_refs, new_process_refs;
2957 struct cfq_queue *__cfqq;
2960 * If there are no process references on the new_cfqq, then it is
2961 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2962 * chain may have dropped their last reference (not just their
2963 * last process reference).
2965 if (!cfqq_process_refs(new_cfqq))
2968 /* Avoid a circular list and skip interim queue merges */
2969 while ((__cfqq = new_cfqq->new_cfqq)) {
2975 process_refs = cfqq_process_refs(cfqq);
2976 new_process_refs = cfqq_process_refs(new_cfqq);
2978 * If the process for the cfqq has gone away, there is no
2979 * sense in merging the queues.
2981 if (process_refs == 0 || new_process_refs == 0)
2985 * Merge in the direction of the lesser amount of work.
2987 if (new_process_refs >= process_refs) {
2988 cfqq->new_cfqq = new_cfqq;
2989 new_cfqq->ref += process_refs;
2991 new_cfqq->new_cfqq = cfqq;
2992 cfqq->ref += new_process_refs;
2996 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2997 struct cfq_group *cfqg, enum wl_class_t wl_class)
2999 struct cfq_queue *queue;
3001 bool key_valid = false;
3002 unsigned long lowest_key = 0;
3003 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
3005 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
3006 /* select the one with lowest rb_key */
3007 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
3009 (!key_valid || time_before(queue->rb_key, lowest_key))) {
3010 lowest_key = queue->rb_key;
3020 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
3024 struct cfq_rb_root *st;
3025 unsigned group_slice;
3026 enum wl_class_t original_class = cfqd->serving_wl_class;
3028 /* Choose next priority. RT > BE > IDLE */
3029 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3030 cfqd->serving_wl_class = RT_WORKLOAD;
3031 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3032 cfqd->serving_wl_class = BE_WORKLOAD;
3034 cfqd->serving_wl_class = IDLE_WORKLOAD;
3035 cfqd->workload_expires = jiffies + 1;
3039 if (original_class != cfqd->serving_wl_class)
3043 * For RT and BE, we have to choose also the type
3044 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3047 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3051 * check workload expiration, and that we still have other queues ready
3053 if (count && !time_after(jiffies, cfqd->workload_expires))
3057 /* otherwise select new workload type */
3058 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3059 cfqd->serving_wl_class);
3060 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3064 * the workload slice is computed as a fraction of target latency
3065 * proportional to the number of queues in that workload, over
3066 * all the queues in the same priority class
3068 group_slice = cfq_group_slice(cfqd, cfqg);
3070 slice = group_slice * count /
3071 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3072 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3075 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3079 * Async queues are currently system wide. Just taking
3080 * proportion of queues with-in same group will lead to higher
3081 * async ratio system wide as generally root group is going
3082 * to have higher weight. A more accurate thing would be to
3083 * calculate system wide asnc/sync ratio.
3085 tmp = cfqd->cfq_target_latency *
3086 cfqg_busy_async_queues(cfqd, cfqg);
3087 tmp = tmp/cfqd->busy_queues;
3088 slice = min_t(unsigned, slice, tmp);
3090 /* async workload slice is scaled down according to
3091 * the sync/async slice ratio. */
3092 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
3094 /* sync workload slice is at least 2 * cfq_slice_idle */
3095 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3097 slice = max_t(unsigned, slice, CFQ_MIN_TT);
3098 cfq_log(cfqd, "workload slice:%d", slice);
3099 cfqd->workload_expires = jiffies + slice;
3102 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3104 struct cfq_rb_root *st = &cfqd->grp_service_tree;
3105 struct cfq_group *cfqg;
3107 if (RB_EMPTY_ROOT(&st->rb))
3109 cfqg = cfq_rb_first_group(st);
3110 update_min_vdisktime(st);
3114 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3116 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3118 cfqd->serving_group = cfqg;
3120 /* Restore the workload type data */
3121 if (cfqg->saved_wl_slice) {
3122 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
3123 cfqd->serving_wl_type = cfqg->saved_wl_type;
3124 cfqd->serving_wl_class = cfqg->saved_wl_class;
3126 cfqd->workload_expires = jiffies - 1;
3128 choose_wl_class_and_type(cfqd, cfqg);
3132 * Select a queue for service. If we have a current active queue,
3133 * check whether to continue servicing it, or retrieve and set a new one.
3135 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3137 struct cfq_queue *cfqq, *new_cfqq = NULL;
3139 cfqq = cfqd->active_queue;
3143 if (!cfqd->rq_queued)
3147 * We were waiting for group to get backlogged. Expire the queue
3149 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3153 * The active queue has run out of time, expire it and select new.
3155 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3157 * If slice had not expired at the completion of last request
3158 * we might not have turned on wait_busy flag. Don't expire
3159 * the queue yet. Allow the group to get backlogged.
3161 * The very fact that we have used the slice, that means we
3162 * have been idling all along on this queue and it should be
3163 * ok to wait for this request to complete.
3165 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3166 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3170 goto check_group_idle;
3174 * The active queue has requests and isn't expired, allow it to
3177 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3181 * If another queue has a request waiting within our mean seek
3182 * distance, let it run. The expire code will check for close
3183 * cooperators and put the close queue at the front of the service
3184 * tree. If possible, merge the expiring queue with the new cfqq.
3186 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3188 if (!cfqq->new_cfqq)
3189 cfq_setup_merge(cfqq, new_cfqq);
3194 * No requests pending. If the active queue still has requests in
3195 * flight or is idling for a new request, allow either of these
3196 * conditions to happen (or time out) before selecting a new queue.
3198 if (timer_pending(&cfqd->idle_slice_timer)) {
3204 * This is a deep seek queue, but the device is much faster than
3205 * the queue can deliver, don't idle
3207 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3208 (cfq_cfqq_slice_new(cfqq) ||
3209 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
3210 cfq_clear_cfqq_deep(cfqq);
3211 cfq_clear_cfqq_idle_window(cfqq);
3214 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3220 * If group idle is enabled and there are requests dispatched from
3221 * this group, wait for requests to complete.
3224 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3225 cfqq->cfqg->dispatched &&
3226 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3232 cfq_slice_expired(cfqd, 0);
3235 * Current queue expired. Check if we have to switch to a new
3239 cfq_choose_cfqg(cfqd);
3241 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3246 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3250 while (cfqq->next_rq) {
3251 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3255 BUG_ON(!list_empty(&cfqq->fifo));
3257 /* By default cfqq is not expired if it is empty. Do it explicitly */
3258 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3263 * Drain our current requests. Used for barriers and when switching
3264 * io schedulers on-the-fly.
3266 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3268 struct cfq_queue *cfqq;
3271 /* Expire the timeslice of the current active queue first */
3272 cfq_slice_expired(cfqd, 0);
3273 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3274 __cfq_set_active_queue(cfqd, cfqq);
3275 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3278 BUG_ON(cfqd->busy_queues);
3280 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3284 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3285 struct cfq_queue *cfqq)
3287 /* the queue hasn't finished any request, can't estimate */
3288 if (cfq_cfqq_slice_new(cfqq))
3290 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
3297 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3299 unsigned int max_dispatch;
3302 * Drain async requests before we start sync IO
3304 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3308 * If this is an async queue and we have sync IO in flight, let it wait
3310 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3313 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3314 if (cfq_class_idle(cfqq))
3318 * Does this cfqq already have too much IO in flight?
3320 if (cfqq->dispatched >= max_dispatch) {
3321 bool promote_sync = false;
3323 * idle queue must always only have a single IO in flight
3325 if (cfq_class_idle(cfqq))
3329 * If there is only one sync queue
3330 * we can ignore async queue here and give the sync
3331 * queue no dispatch limit. The reason is a sync queue can
3332 * preempt async queue, limiting the sync queue doesn't make
3333 * sense. This is useful for aiostress test.
3335 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3336 promote_sync = true;
3339 * We have other queues, don't allow more IO from this one
3341 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3346 * Sole queue user, no limit
3348 if (cfqd->busy_queues == 1 || promote_sync)
3352 * Normally we start throttling cfqq when cfq_quantum/2
3353 * requests have been dispatched. But we can drive
3354 * deeper queue depths at the beginning of slice
3355 * subjected to upper limit of cfq_quantum.
3357 max_dispatch = cfqd->cfq_quantum;
3361 * Async queues must wait a bit before being allowed dispatch.
3362 * We also ramp up the dispatch depth gradually for async IO,
3363 * based on the last sync IO we serviced
3365 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3366 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
3369 depth = last_sync / cfqd->cfq_slice[1];
3370 if (!depth && !cfqq->dispatched)
3372 if (depth < max_dispatch)
3373 max_dispatch = depth;
3377 * If we're below the current max, allow a dispatch
3379 return cfqq->dispatched < max_dispatch;
3383 * Dispatch a request from cfqq, moving them to the request queue
3386 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3390 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3392 if (!cfq_may_dispatch(cfqd, cfqq))
3396 * follow expired path, else get first next available
3398 rq = cfq_check_fifo(cfqq);
3403 * insert request into driver dispatch list
3405 cfq_dispatch_insert(cfqd->queue, rq);
3407 if (!cfqd->active_cic) {
3408 struct cfq_io_cq *cic = RQ_CIC(rq);
3410 atomic_long_inc(&cic->icq.ioc->refcount);
3411 cfqd->active_cic = cic;
3418 * Find the cfqq that we need to service and move a request from that to the
3421 static int cfq_dispatch_requests(struct request_queue *q, int force)
3423 struct cfq_data *cfqd = q->elevator->elevator_data;
3424 struct cfq_queue *cfqq;
3426 if (!cfqd->busy_queues)
3429 if (unlikely(force))
3430 return cfq_forced_dispatch(cfqd);
3432 cfqq = cfq_select_queue(cfqd);
3437 * Dispatch a request from this cfqq, if it is allowed
3439 if (!cfq_dispatch_request(cfqd, cfqq))
3442 cfqq->slice_dispatch++;
3443 cfq_clear_cfqq_must_dispatch(cfqq);
3446 * expire an async queue immediately if it has used up its slice. idle
3447 * queue always expire after 1 dispatch round.
3449 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3450 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3451 cfq_class_idle(cfqq))) {
3452 cfqq->slice_end = jiffies + 1;
3453 cfq_slice_expired(cfqd, 0);
3456 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3461 * task holds one reference to the queue, dropped when task exits. each rq
3462 * in-flight on this queue also holds a reference, dropped when rq is freed.
3464 * Each cfq queue took a reference on the parent group. Drop it now.
3465 * queue lock must be held here.
3467 static void cfq_put_queue(struct cfq_queue *cfqq)
3469 struct cfq_data *cfqd = cfqq->cfqd;
3470 struct cfq_group *cfqg;
3472 BUG_ON(cfqq->ref <= 0);
3478 cfq_log_cfqq(cfqd, cfqq, "put_queue");
3479 BUG_ON(rb_first(&cfqq->sort_list));
3480 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3483 if (unlikely(cfqd->active_queue == cfqq)) {
3484 __cfq_slice_expired(cfqd, cfqq, 0);
3485 cfq_schedule_dispatch(cfqd);
3488 BUG_ON(cfq_cfqq_on_rr(cfqq));
3489 kmem_cache_free(cfq_pool, cfqq);
3493 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3495 struct cfq_queue *__cfqq, *next;
3498 * If this queue was scheduled to merge with another queue, be
3499 * sure to drop the reference taken on that queue (and others in
3500 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3502 __cfqq = cfqq->new_cfqq;
3504 if (__cfqq == cfqq) {
3505 WARN(1, "cfqq->new_cfqq loop detected\n");
3508 next = __cfqq->new_cfqq;
3509 cfq_put_queue(__cfqq);
3514 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3516 if (unlikely(cfqq == cfqd->active_queue)) {
3517 __cfq_slice_expired(cfqd, cfqq, 0);
3518 cfq_schedule_dispatch(cfqd);
3521 cfq_put_cooperator(cfqq);
3523 cfq_put_queue(cfqq);
3526 static void cfq_init_icq(struct io_cq *icq)
3528 struct cfq_io_cq *cic = icq_to_cic(icq);
3530 cic->ttime.last_end_request = jiffies;
3533 static void cfq_exit_icq(struct io_cq *icq)
3535 struct cfq_io_cq *cic = icq_to_cic(icq);
3536 struct cfq_data *cfqd = cic_to_cfqd(cic);
3538 if (cic_to_cfqq(cic, false)) {
3539 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3540 cic_set_cfqq(cic, NULL, false);
3543 if (cic_to_cfqq(cic, true)) {
3544 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3545 cic_set_cfqq(cic, NULL, true);
3549 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3551 struct task_struct *tsk = current;
3554 if (!cfq_cfqq_prio_changed(cfqq))
3557 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3558 switch (ioprio_class) {
3560 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3561 case IOPRIO_CLASS_NONE:
3563 * no prio set, inherit CPU scheduling settings
3565 cfqq->ioprio = task_nice_ioprio(tsk);
3566 cfqq->ioprio_class = task_nice_ioclass(tsk);
3568 case IOPRIO_CLASS_RT:
3569 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3570 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3572 case IOPRIO_CLASS_BE:
3573 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3574 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3576 case IOPRIO_CLASS_IDLE:
3577 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3579 cfq_clear_cfqq_idle_window(cfqq);
3584 * keep track of original prio settings in case we have to temporarily
3585 * elevate the priority of this queue
3587 cfqq->org_ioprio = cfqq->ioprio;
3588 cfq_clear_cfqq_prio_changed(cfqq);
3591 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3593 int ioprio = cic->icq.ioc->ioprio;
3594 struct cfq_data *cfqd = cic_to_cfqd(cic);
3595 struct cfq_queue *cfqq;
3598 * Check whether ioprio has changed. The condition may trigger
3599 * spuriously on a newly created cic but there's no harm.
3601 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3604 cfqq = cic_to_cfqq(cic, false);
3606 cfq_put_queue(cfqq);
3607 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3608 cic_set_cfqq(cic, cfqq, false);
3611 cfqq = cic_to_cfqq(cic, true);
3613 cfq_mark_cfqq_prio_changed(cfqq);
3615 cic->ioprio = ioprio;
3618 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3619 pid_t pid, bool is_sync)
3621 RB_CLEAR_NODE(&cfqq->rb_node);
3622 RB_CLEAR_NODE(&cfqq->p_node);
3623 INIT_LIST_HEAD(&cfqq->fifo);
3628 cfq_mark_cfqq_prio_changed(cfqq);
3631 if (!cfq_class_idle(cfqq))
3632 cfq_mark_cfqq_idle_window(cfqq);
3633 cfq_mark_cfqq_sync(cfqq);
3638 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3639 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3641 struct cfq_data *cfqd = cic_to_cfqd(cic);
3642 struct cfq_queue *cfqq;
3646 serial_nr = bio_blkcg(bio)->css.serial_nr;
3650 * Check whether blkcg has changed. The condition may trigger
3651 * spuriously on a newly created cic but there's no harm.
3653 if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3657 * Drop reference to queues. New queues will be assigned in new
3658 * group upon arrival of fresh requests.
3660 cfqq = cic_to_cfqq(cic, false);
3662 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3663 cic_set_cfqq(cic, NULL, false);
3664 cfq_put_queue(cfqq);
3667 cfqq = cic_to_cfqq(cic, true);
3669 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3670 cic_set_cfqq(cic, NULL, true);
3671 cfq_put_queue(cfqq);
3674 cic->blkcg_serial_nr = serial_nr;
3677 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3678 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3680 static struct cfq_queue **
3681 cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3683 switch (ioprio_class) {
3684 case IOPRIO_CLASS_RT:
3685 return &cfqg->async_cfqq[0][ioprio];
3686 case IOPRIO_CLASS_NONE:
3687 ioprio = IOPRIO_NORM;
3689 case IOPRIO_CLASS_BE:
3690 return &cfqg->async_cfqq[1][ioprio];
3691 case IOPRIO_CLASS_IDLE:
3692 return &cfqg->async_idle_cfqq;
3698 static struct cfq_queue *
3699 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3702 int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3703 int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3704 struct cfq_queue **async_cfqq = NULL;
3705 struct cfq_queue *cfqq;
3706 struct cfq_group *cfqg;
3709 cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3711 cfqq = &cfqd->oom_cfqq;
3716 if (!ioprio_valid(cic->ioprio)) {
3717 struct task_struct *tsk = current;
3718 ioprio = task_nice_ioprio(tsk);
3719 ioprio_class = task_nice_ioclass(tsk);
3721 async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3727 cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
3730 cfqq = &cfqd->oom_cfqq;
3734 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3735 cfq_init_prio_data(cfqq, cic);
3736 cfq_link_cfqq_cfqg(cfqq, cfqg);
3737 cfq_log_cfqq(cfqd, cfqq, "alloced");
3740 /* a new async queue is created, pin and remember */
3751 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3753 unsigned long elapsed = jiffies - ttime->last_end_request;
3754 elapsed = min(elapsed, 2UL * slice_idle);
3756 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3757 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3758 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3762 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3763 struct cfq_io_cq *cic)
3765 if (cfq_cfqq_sync(cfqq)) {
3766 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3767 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3768 cfqd->cfq_slice_idle);
3770 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3771 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3776 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3780 sector_t n_sec = blk_rq_sectors(rq);
3781 if (cfqq->last_request_pos) {
3782 if (cfqq->last_request_pos < blk_rq_pos(rq))
3783 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3785 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3788 cfqq->seek_history <<= 1;
3789 if (blk_queue_nonrot(cfqd->queue))
3790 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3792 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3796 * Disable idle window if the process thinks too long or seeks so much that
3800 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3801 struct cfq_io_cq *cic)
3803 int old_idle, enable_idle;
3806 * Don't idle for async or idle io prio class
3808 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3811 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3813 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3814 cfq_mark_cfqq_deep(cfqq);
3816 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3818 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3819 !cfqd->cfq_slice_idle ||
3820 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3822 else if (sample_valid(cic->ttime.ttime_samples)) {
3823 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3829 if (old_idle != enable_idle) {
3830 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3832 cfq_mark_cfqq_idle_window(cfqq);
3834 cfq_clear_cfqq_idle_window(cfqq);
3839 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3840 * no or if we aren't sure, a 1 will cause a preempt.
3843 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3846 struct cfq_queue *cfqq;
3848 cfqq = cfqd->active_queue;
3852 if (cfq_class_idle(new_cfqq))
3855 if (cfq_class_idle(cfqq))
3859 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3861 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3865 * if the new request is sync, but the currently running queue is
3866 * not, let the sync request have priority.
3868 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3871 if (new_cfqq->cfqg != cfqq->cfqg)
3874 if (cfq_slice_used(cfqq))
3877 /* Allow preemption only if we are idling on sync-noidle tree */
3878 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3879 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3880 new_cfqq->service_tree->count == 2 &&
3881 RB_EMPTY_ROOT(&cfqq->sort_list))
3885 * So both queues are sync. Let the new request get disk time if
3886 * it's a metadata request and the current queue is doing regular IO.
3888 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3892 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3894 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3897 /* An idle queue should not be idle now for some reason */
3898 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3901 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3905 * if this request is as-good as one we would expect from the
3906 * current cfqq, let it preempt
3908 if (cfq_rq_close(cfqd, cfqq, rq))
3915 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3916 * let it have half of its nominal slice.
3918 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3920 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3922 cfq_log_cfqq(cfqd, cfqq, "preempt");
3923 cfq_slice_expired(cfqd, 1);
3926 * workload type is changed, don't save slice, otherwise preempt
3929 if (old_type != cfqq_type(cfqq))
3930 cfqq->cfqg->saved_wl_slice = 0;
3933 * Put the new queue at the front of the of the current list,
3934 * so we know that it will be selected next.
3936 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3938 cfq_service_tree_add(cfqd, cfqq, 1);
3940 cfqq->slice_end = 0;
3941 cfq_mark_cfqq_slice_new(cfqq);
3945 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3946 * something we should do about it
3949 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3952 struct cfq_io_cq *cic = RQ_CIC(rq);
3955 if (rq->cmd_flags & REQ_PRIO)
3956 cfqq->prio_pending++;
3958 cfq_update_io_thinktime(cfqd, cfqq, cic);
3959 cfq_update_io_seektime(cfqd, cfqq, rq);
3960 cfq_update_idle_window(cfqd, cfqq, cic);
3962 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3964 if (cfqq == cfqd->active_queue) {
3966 * Remember that we saw a request from this process, but
3967 * don't start queuing just yet. Otherwise we risk seeing lots
3968 * of tiny requests, because we disrupt the normal plugging
3969 * and merging. If the request is already larger than a single
3970 * page, let it rip immediately. For that case we assume that
3971 * merging is already done. Ditto for a busy system that
3972 * has other work pending, don't risk delaying until the
3973 * idle timer unplug to continue working.
3975 if (cfq_cfqq_wait_request(cfqq)) {
3976 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3977 cfqd->busy_queues > 1) {
3978 cfq_del_timer(cfqd, cfqq);
3979 cfq_clear_cfqq_wait_request(cfqq);
3980 __blk_run_queue(cfqd->queue);
3982 cfqg_stats_update_idle_time(cfqq->cfqg);
3983 cfq_mark_cfqq_must_dispatch(cfqq);
3986 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3988 * not the active queue - expire current slice if it is
3989 * idle and has expired it's mean thinktime or this new queue
3990 * has some old slice time left and is of higher priority or
3991 * this new queue is RT and the current one is BE
3993 cfq_preempt_queue(cfqd, cfqq);
3994 __blk_run_queue(cfqd->queue);
3998 static void cfq_insert_request(struct request_queue *q, struct request *rq)
4000 struct cfq_data *cfqd = q->elevator->elevator_data;
4001 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4003 cfq_log_cfqq(cfqd, cfqq, "insert_request");
4004 cfq_init_prio_data(cfqq, RQ_CIC(rq));
4006 rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
4007 list_add_tail(&rq->queuelist, &cfqq->fifo);
4009 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
4011 cfq_rq_enqueued(cfqd, cfqq, rq);
4015 * Update hw_tag based on peak queue depth over 50 samples under
4018 static void cfq_update_hw_tag(struct cfq_data *cfqd)
4020 struct cfq_queue *cfqq = cfqd->active_queue;
4022 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
4023 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
4025 if (cfqd->hw_tag == 1)
4028 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
4029 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
4033 * If active queue hasn't enough requests and can idle, cfq might not
4034 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4037 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4038 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4039 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4042 if (cfqd->hw_tag_samples++ < 50)
4045 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4051 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4053 struct cfq_io_cq *cic = cfqd->active_cic;
4055 /* If the queue already has requests, don't wait */
4056 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4059 /* If there are other queues in the group, don't wait */
4060 if (cfqq->cfqg->nr_cfqq > 1)
4063 /* the only queue in the group, but think time is big */
4064 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4067 if (cfq_slice_used(cfqq))
4070 /* if slice left is less than think time, wait busy */
4071 if (cic && sample_valid(cic->ttime.ttime_samples)
4072 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
4076 * If think times is less than a jiffy than ttime_mean=0 and above
4077 * will not be true. It might happen that slice has not expired yet
4078 * but will expire soon (4-5 ns) during select_queue(). To cover the
4079 * case where think time is less than a jiffy, mark the queue wait
4080 * busy if only 1 jiffy is left in the slice.
4082 if (cfqq->slice_end - jiffies == 1)
4088 static void cfq_completed_request(struct request_queue *q, struct request *rq)
4090 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4091 struct cfq_data *cfqd = cfqq->cfqd;
4092 const int sync = rq_is_sync(rq);
4096 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4097 !!(rq->cmd_flags & REQ_NOIDLE));
4099 cfq_update_hw_tag(cfqd);
4101 WARN_ON(!cfqd->rq_in_driver);
4102 WARN_ON(!cfqq->dispatched);
4103 cfqd->rq_in_driver--;
4105 (RQ_CFQG(rq))->dispatched--;
4106 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4107 rq_io_start_time_ns(rq), rq->cmd_flags);
4109 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4112 struct cfq_rb_root *st;
4114 RQ_CIC(rq)->ttime.last_end_request = now;
4116 if (cfq_cfqq_on_rr(cfqq))
4117 st = cfqq->service_tree;
4119 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4122 st->ttime.last_end_request = now;
4123 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
4124 cfqd->last_delayed_sync = now;
4127 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4128 cfqq->cfqg->ttime.last_end_request = now;
4132 * If this is the active queue, check if it needs to be expired,
4133 * or if we want to idle in case it has no pending requests.
4135 if (cfqd->active_queue == cfqq) {
4136 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4138 if (cfq_cfqq_slice_new(cfqq)) {
4139 cfq_set_prio_slice(cfqd, cfqq);
4140 cfq_clear_cfqq_slice_new(cfqq);
4144 * Should we wait for next request to come in before we expire
4147 if (cfq_should_wait_busy(cfqd, cfqq)) {
4148 unsigned long extend_sl = cfqd->cfq_slice_idle;
4149 if (!cfqd->cfq_slice_idle)
4150 extend_sl = cfqd->cfq_group_idle;
4151 cfqq->slice_end = jiffies + extend_sl;
4152 cfq_mark_cfqq_wait_busy(cfqq);
4153 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4157 * Idling is not enabled on:
4159 * - idle-priority queues
4161 * - queues with still some requests queued
4162 * - when there is a close cooperator
4164 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4165 cfq_slice_expired(cfqd, 1);
4166 else if (sync && cfqq_empty &&
4167 !cfq_close_cooperator(cfqd, cfqq)) {
4168 cfq_arm_slice_timer(cfqd);
4172 if (!cfqd->rq_in_driver)
4173 cfq_schedule_dispatch(cfqd);
4176 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4178 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4179 cfq_mark_cfqq_must_alloc_slice(cfqq);
4180 return ELV_MQUEUE_MUST;
4183 return ELV_MQUEUE_MAY;
4186 static int cfq_may_queue(struct request_queue *q, int rw)
4188 struct cfq_data *cfqd = q->elevator->elevator_data;
4189 struct task_struct *tsk = current;
4190 struct cfq_io_cq *cic;
4191 struct cfq_queue *cfqq;
4194 * don't force setup of a queue from here, as a call to may_queue
4195 * does not necessarily imply that a request actually will be queued.
4196 * so just lookup a possibly existing queue, or return 'may queue'
4199 cic = cfq_cic_lookup(cfqd, tsk->io_context);
4201 return ELV_MQUEUE_MAY;
4203 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
4205 cfq_init_prio_data(cfqq, cic);
4207 return __cfq_may_queue(cfqq);
4210 return ELV_MQUEUE_MAY;
4214 * queue lock held here
4216 static void cfq_put_request(struct request *rq)
4218 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4221 const int rw = rq_data_dir(rq);
4223 BUG_ON(!cfqq->allocated[rw]);
4224 cfqq->allocated[rw]--;
4226 /* Put down rq reference on cfqg */
4227 cfqg_put(RQ_CFQG(rq));
4228 rq->elv.priv[0] = NULL;
4229 rq->elv.priv[1] = NULL;
4231 cfq_put_queue(cfqq);
4235 static struct cfq_queue *
4236 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4237 struct cfq_queue *cfqq)
4239 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4240 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4241 cfq_mark_cfqq_coop(cfqq->new_cfqq);
4242 cfq_put_queue(cfqq);
4243 return cic_to_cfqq(cic, 1);
4247 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4248 * was the last process referring to said cfqq.
4250 static struct cfq_queue *
4251 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4253 if (cfqq_process_refs(cfqq) == 1) {
4254 cfqq->pid = current->pid;
4255 cfq_clear_cfqq_coop(cfqq);
4256 cfq_clear_cfqq_split_coop(cfqq);
4260 cic_set_cfqq(cic, NULL, 1);
4262 cfq_put_cooperator(cfqq);
4264 cfq_put_queue(cfqq);
4268 * Allocate cfq data structures associated with this request.
4271 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4274 struct cfq_data *cfqd = q->elevator->elevator_data;
4275 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4276 const int rw = rq_data_dir(rq);
4277 const bool is_sync = rq_is_sync(rq);
4278 struct cfq_queue *cfqq;
4280 spin_lock_irq(q->queue_lock);
4282 check_ioprio_changed(cic, bio);
4283 check_blkcg_changed(cic, bio);
4285 cfqq = cic_to_cfqq(cic, is_sync);
4286 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4288 cfq_put_queue(cfqq);
4289 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4290 cic_set_cfqq(cic, cfqq, is_sync);
4293 * If the queue was seeky for too long, break it apart.
4295 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4296 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4297 cfqq = split_cfqq(cic, cfqq);
4303 * Check to see if this queue is scheduled to merge with
4304 * another, closely cooperating queue. The merging of
4305 * queues happens here as it must be done in process context.
4306 * The reference on new_cfqq was taken in merge_cfqqs.
4309 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4312 cfqq->allocated[rw]++;
4315 cfqg_get(cfqq->cfqg);
4316 rq->elv.priv[0] = cfqq;
4317 rq->elv.priv[1] = cfqq->cfqg;
4318 spin_unlock_irq(q->queue_lock);
4322 static void cfq_kick_queue(struct work_struct *work)
4324 struct cfq_data *cfqd =
4325 container_of(work, struct cfq_data, unplug_work);
4326 struct request_queue *q = cfqd->queue;
4328 spin_lock_irq(q->queue_lock);
4329 __blk_run_queue(cfqd->queue);
4330 spin_unlock_irq(q->queue_lock);
4334 * Timer running if the active_queue is currently idling inside its time slice
4336 static void cfq_idle_slice_timer(unsigned long data)
4338 struct cfq_data *cfqd = (struct cfq_data *) data;
4339 struct cfq_queue *cfqq;
4340 unsigned long flags;
4343 cfq_log(cfqd, "idle timer fired");
4345 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4347 cfqq = cfqd->active_queue;
4352 * We saw a request before the queue expired, let it through
4354 if (cfq_cfqq_must_dispatch(cfqq))
4360 if (cfq_slice_used(cfqq))
4364 * only expire and reinvoke request handler, if there are
4365 * other queues with pending requests
4367 if (!cfqd->busy_queues)
4371 * not expired and it has a request pending, let it dispatch
4373 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4377 * Queue depth flag is reset only when the idle didn't succeed
4379 cfq_clear_cfqq_deep(cfqq);
4382 cfq_slice_expired(cfqd, timed_out);
4384 cfq_schedule_dispatch(cfqd);
4386 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4389 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4391 del_timer_sync(&cfqd->idle_slice_timer);
4392 cancel_work_sync(&cfqd->unplug_work);
4395 static void cfq_exit_queue(struct elevator_queue *e)
4397 struct cfq_data *cfqd = e->elevator_data;
4398 struct request_queue *q = cfqd->queue;
4400 cfq_shutdown_timer_wq(cfqd);
4402 spin_lock_irq(q->queue_lock);
4404 if (cfqd->active_queue)
4405 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4407 spin_unlock_irq(q->queue_lock);
4409 cfq_shutdown_timer_wq(cfqd);
4411 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4412 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4414 kfree(cfqd->root_group);
4419 static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4421 struct cfq_data *cfqd;
4422 struct blkcg_gq *blkg __maybe_unused;
4424 struct elevator_queue *eq;
4426 eq = elevator_alloc(q, e);
4430 cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4432 kobject_put(&eq->kobj);
4435 eq->elevator_data = cfqd;
4438 spin_lock_irq(q->queue_lock);
4440 spin_unlock_irq(q->queue_lock);
4442 /* Init root service tree */
4443 cfqd->grp_service_tree = CFQ_RB_ROOT;
4445 /* Init root group and prefer root group over other groups by default */
4446 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4447 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4451 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4454 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4455 GFP_KERNEL, cfqd->queue->node);
4456 if (!cfqd->root_group)
4459 cfq_init_cfqg_base(cfqd->root_group);
4461 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
4462 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
4465 * Not strictly needed (since RB_ROOT just clears the node and we
4466 * zeroed cfqd on alloc), but better be safe in case someone decides
4467 * to add magic to the rb code
4469 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4470 cfqd->prio_trees[i] = RB_ROOT;
4473 * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
4474 * Grab a permanent reference to it, so that the normal code flow
4475 * will not attempt to free it. oom_cfqq is linked to root_group
4476 * but shouldn't hold a reference as it'll never be unlinked. Lose
4477 * the reference from linking right away.
4479 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4480 cfqd->oom_cfqq.ref++;
4482 spin_lock_irq(q->queue_lock);
4483 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4484 cfqg_put(cfqd->root_group);
4485 spin_unlock_irq(q->queue_lock);
4487 init_timer(&cfqd->idle_slice_timer);
4488 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4489 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4491 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4493 cfqd->cfq_quantum = cfq_quantum;
4494 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4495 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4496 cfqd->cfq_back_max = cfq_back_max;
4497 cfqd->cfq_back_penalty = cfq_back_penalty;
4498 cfqd->cfq_slice[0] = cfq_slice_async;
4499 cfqd->cfq_slice[1] = cfq_slice_sync;
4500 cfqd->cfq_target_latency = cfq_target_latency;
4501 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4502 cfqd->cfq_slice_idle = cfq_slice_idle;
4503 cfqd->cfq_group_idle = cfq_group_idle;
4504 cfqd->cfq_latency = 1;
4507 * we optimistically start assuming sync ops weren't delayed in last
4508 * second, in order to have larger depth for async operations.
4510 cfqd->last_delayed_sync = jiffies - HZ;
4515 kobject_put(&eq->kobj);
4519 static void cfq_registered_queue(struct request_queue *q)
4521 struct elevator_queue *e = q->elevator;
4522 struct cfq_data *cfqd = e->elevator_data;
4525 * Default to IOPS mode with no idling for SSDs
4527 if (blk_queue_nonrot(q))
4528 cfqd->cfq_slice_idle = 0;
4532 * sysfs parts below -->
4535 cfq_var_show(unsigned int var, char *page)
4537 return sprintf(page, "%u\n", var);
4541 cfq_var_store(unsigned int *var, const char *page, size_t count)
4543 char *p = (char *) page;
4545 *var = simple_strtoul(p, &p, 10);
4549 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4550 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4552 struct cfq_data *cfqd = e->elevator_data; \
4553 unsigned int __data = __VAR; \
4555 __data = jiffies_to_msecs(__data); \
4556 return cfq_var_show(__data, (page)); \
4558 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4559 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4560 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4561 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4562 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4563 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4564 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4565 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4566 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4567 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4568 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4569 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4570 #undef SHOW_FUNCTION
4572 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4573 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4575 struct cfq_data *cfqd = e->elevator_data; \
4576 unsigned int __data; \
4577 int ret = cfq_var_store(&__data, (page), count); \
4578 if (__data < (MIN)) \
4580 else if (__data > (MAX)) \
4583 *(__PTR) = msecs_to_jiffies(__data); \
4585 *(__PTR) = __data; \
4588 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4589 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4591 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4593 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4594 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4596 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4597 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4598 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4599 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4600 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4602 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4603 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4604 #undef STORE_FUNCTION
4606 #define CFQ_ATTR(name) \
4607 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4609 static struct elv_fs_entry cfq_attrs[] = {
4611 CFQ_ATTR(fifo_expire_sync),
4612 CFQ_ATTR(fifo_expire_async),
4613 CFQ_ATTR(back_seek_max),
4614 CFQ_ATTR(back_seek_penalty),
4615 CFQ_ATTR(slice_sync),
4616 CFQ_ATTR(slice_async),
4617 CFQ_ATTR(slice_async_rq),
4618 CFQ_ATTR(slice_idle),
4619 CFQ_ATTR(group_idle),
4620 CFQ_ATTR(low_latency),
4621 CFQ_ATTR(target_latency),
4625 static struct elevator_type iosched_cfq = {
4627 .elevator_merge_fn = cfq_merge,
4628 .elevator_merged_fn = cfq_merged_request,
4629 .elevator_merge_req_fn = cfq_merged_requests,
4630 .elevator_allow_merge_fn = cfq_allow_merge,
4631 .elevator_bio_merged_fn = cfq_bio_merged,
4632 .elevator_dispatch_fn = cfq_dispatch_requests,
4633 .elevator_add_req_fn = cfq_insert_request,
4634 .elevator_activate_req_fn = cfq_activate_request,
4635 .elevator_deactivate_req_fn = cfq_deactivate_request,
4636 .elevator_completed_req_fn = cfq_completed_request,
4637 .elevator_former_req_fn = elv_rb_former_request,
4638 .elevator_latter_req_fn = elv_rb_latter_request,
4639 .elevator_init_icq_fn = cfq_init_icq,
4640 .elevator_exit_icq_fn = cfq_exit_icq,
4641 .elevator_set_req_fn = cfq_set_request,
4642 .elevator_put_req_fn = cfq_put_request,
4643 .elevator_may_queue_fn = cfq_may_queue,
4644 .elevator_init_fn = cfq_init_queue,
4645 .elevator_exit_fn = cfq_exit_queue,
4646 .elevator_registered_fn = cfq_registered_queue,
4648 .icq_size = sizeof(struct cfq_io_cq),
4649 .icq_align = __alignof__(struct cfq_io_cq),
4650 .elevator_attrs = cfq_attrs,
4651 .elevator_name = "cfq",
4652 .elevator_owner = THIS_MODULE,
4655 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4656 static struct blkcg_policy blkcg_policy_cfq = {
4657 .cftypes = cfq_blkcg_files,
4659 .cpd_alloc_fn = cfq_cpd_alloc,
4660 .cpd_init_fn = cfq_cpd_init,
4661 .cpd_free_fn = cfq_cpd_free,
4663 .pd_alloc_fn = cfq_pd_alloc,
4664 .pd_init_fn = cfq_pd_init,
4665 .pd_offline_fn = cfq_pd_offline,
4666 .pd_free_fn = cfq_pd_free,
4667 .pd_reset_stats_fn = cfq_pd_reset_stats,
4671 static int __init cfq_init(void)
4676 * could be 0 on HZ < 1000 setups
4678 if (!cfq_slice_async)
4679 cfq_slice_async = 1;
4680 if (!cfq_slice_idle)
4683 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4684 if (!cfq_group_idle)
4687 ret = blkcg_policy_register(&blkcg_policy_cfq);
4695 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4699 ret = elv_register(&iosched_cfq);
4706 kmem_cache_destroy(cfq_pool);
4708 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4709 blkcg_policy_unregister(&blkcg_policy_cfq);
4714 static void __exit cfq_exit(void)
4716 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4717 blkcg_policy_unregister(&blkcg_policy_cfq);
4719 elv_unregister(&iosched_cfq);
4720 kmem_cache_destroy(cfq_pool);
4723 module_init(cfq_init);
4724 module_exit(cfq_exit);
4726 MODULE_AUTHOR("Jens Axboe");
4727 MODULE_LICENSE("GPL");
4728 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");