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 pd;
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 */
307 struct cfqg_stats dead_stats; /* stats pushed from dead children */
311 struct io_cq icq; /* must be the first member */
312 struct cfq_queue *cfqq[2];
313 struct cfq_ttime ttime;
314 int ioprio; /* the current ioprio */
315 #ifdef CONFIG_CFQ_GROUP_IOSCHED
316 uint64_t blkcg_serial_nr; /* the current blkcg serial */
321 * Per block device queue structure
324 struct request_queue *queue;
325 /* Root service tree for cfq_groups */
326 struct cfq_rb_root grp_service_tree;
327 struct cfq_group *root_group;
330 * The priority currently being served
332 enum wl_class_t serving_wl_class;
333 enum wl_type_t serving_wl_type;
334 unsigned long workload_expires;
335 struct cfq_group *serving_group;
338 * Each priority tree is sorted by next_request position. These
339 * trees are used when determining if two or more queues are
340 * interleaving requests (see cfq_close_cooperator).
342 struct rb_root prio_trees[CFQ_PRIO_LISTS];
344 unsigned int busy_queues;
345 unsigned int busy_sync_queues;
351 * queue-depth detection
357 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
358 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
361 int hw_tag_est_depth;
362 unsigned int hw_tag_samples;
365 * idle window management
367 struct timer_list idle_slice_timer;
368 struct work_struct unplug_work;
370 struct cfq_queue *active_queue;
371 struct cfq_io_cq *active_cic;
374 * async queue for each priority case
376 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
377 struct cfq_queue *async_idle_cfqq;
379 sector_t last_position;
382 * tunables, see top of file
384 unsigned int cfq_quantum;
385 unsigned int cfq_fifo_expire[2];
386 unsigned int cfq_back_penalty;
387 unsigned int cfq_back_max;
388 unsigned int cfq_slice[2];
389 unsigned int cfq_slice_async_rq;
390 unsigned int cfq_slice_idle;
391 unsigned int cfq_group_idle;
392 unsigned int cfq_latency;
393 unsigned int cfq_target_latency;
396 * Fallback dummy cfqq for extreme OOM conditions
398 struct cfq_queue oom_cfqq;
400 unsigned long last_delayed_sync;
403 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
405 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
406 enum wl_class_t class,
412 if (class == IDLE_WORKLOAD)
413 return &cfqg->service_tree_idle;
415 return &cfqg->service_trees[class][type];
418 enum cfqq_state_flags {
419 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
420 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
421 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
422 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
423 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
424 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
425 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
426 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
427 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
428 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
429 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
430 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
431 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
434 #define CFQ_CFQQ_FNS(name) \
435 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
437 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
439 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
441 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
443 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
445 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
449 CFQ_CFQQ_FNS(wait_request);
450 CFQ_CFQQ_FNS(must_dispatch);
451 CFQ_CFQQ_FNS(must_alloc_slice);
452 CFQ_CFQQ_FNS(fifo_expire);
453 CFQ_CFQQ_FNS(idle_window);
454 CFQ_CFQQ_FNS(prio_changed);
455 CFQ_CFQQ_FNS(slice_new);
458 CFQ_CFQQ_FNS(split_coop);
460 CFQ_CFQQ_FNS(wait_busy);
463 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
465 /* cfqg stats flags */
466 enum cfqg_stats_flags {
467 CFQG_stats_waiting = 0,
472 #define CFQG_FLAG_FNS(name) \
473 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
475 stats->flags |= (1 << CFQG_stats_##name); \
477 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
479 stats->flags &= ~(1 << CFQG_stats_##name); \
481 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
483 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
486 CFQG_FLAG_FNS(waiting)
487 CFQG_FLAG_FNS(idling)
491 /* This should be called with the queue_lock held. */
492 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
494 unsigned long long now;
496 if (!cfqg_stats_waiting(stats))
500 if (time_after64(now, stats->start_group_wait_time))
501 blkg_stat_add(&stats->group_wait_time,
502 now - stats->start_group_wait_time);
503 cfqg_stats_clear_waiting(stats);
506 /* This should be called with the queue_lock held. */
507 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
508 struct cfq_group *curr_cfqg)
510 struct cfqg_stats *stats = &cfqg->stats;
512 if (cfqg_stats_waiting(stats))
514 if (cfqg == curr_cfqg)
516 stats->start_group_wait_time = sched_clock();
517 cfqg_stats_mark_waiting(stats);
520 /* This should be called with the queue_lock held. */
521 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
523 unsigned long long now;
525 if (!cfqg_stats_empty(stats))
529 if (time_after64(now, stats->start_empty_time))
530 blkg_stat_add(&stats->empty_time,
531 now - stats->start_empty_time);
532 cfqg_stats_clear_empty(stats);
535 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
537 blkg_stat_add(&cfqg->stats.dequeue, 1);
540 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
542 struct cfqg_stats *stats = &cfqg->stats;
544 if (blkg_rwstat_total(&stats->queued))
548 * group is already marked empty. This can happen if cfqq got new
549 * request in parent group and moved to this group while being added
550 * to service tree. Just ignore the event and move on.
552 if (cfqg_stats_empty(stats))
555 stats->start_empty_time = sched_clock();
556 cfqg_stats_mark_empty(stats);
559 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
561 struct cfqg_stats *stats = &cfqg->stats;
563 if (cfqg_stats_idling(stats)) {
564 unsigned long long now = sched_clock();
566 if (time_after64(now, stats->start_idle_time))
567 blkg_stat_add(&stats->idle_time,
568 now - stats->start_idle_time);
569 cfqg_stats_clear_idling(stats);
573 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
575 struct cfqg_stats *stats = &cfqg->stats;
577 BUG_ON(cfqg_stats_idling(stats));
579 stats->start_idle_time = sched_clock();
580 cfqg_stats_mark_idling(stats);
583 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
585 struct cfqg_stats *stats = &cfqg->stats;
587 blkg_stat_add(&stats->avg_queue_size_sum,
588 blkg_rwstat_total(&stats->queued));
589 blkg_stat_add(&stats->avg_queue_size_samples, 1);
590 cfqg_stats_update_group_wait_time(stats);
593 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
595 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
596 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
597 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
598 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
599 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
600 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
601 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
603 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
605 #ifdef CONFIG_CFQ_GROUP_IOSCHED
607 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
609 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
612 static struct cfq_group_data
613 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
615 return cpd ? container_of(cpd, struct cfq_group_data, pd) : NULL;
618 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
620 return pd_to_blkg(&cfqg->pd);
623 static struct blkcg_policy blkcg_policy_cfq;
625 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
627 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
630 static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
632 return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
635 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
637 struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
639 return pblkg ? blkg_to_cfqg(pblkg) : NULL;
642 static inline void cfqg_get(struct cfq_group *cfqg)
644 return blkg_get(cfqg_to_blkg(cfqg));
647 static inline void cfqg_put(struct cfq_group *cfqg)
649 return blkg_put(cfqg_to_blkg(cfqg));
652 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
655 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
656 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
657 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
658 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
662 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
665 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
666 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
669 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
670 struct cfq_group *curr_cfqg, int rw)
672 blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
673 cfqg_stats_end_empty_time(&cfqg->stats);
674 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
677 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
678 unsigned long time, unsigned long unaccounted_time)
680 blkg_stat_add(&cfqg->stats.time, time);
681 #ifdef CONFIG_DEBUG_BLK_CGROUP
682 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
686 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
688 blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
691 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
693 blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
696 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
697 uint64_t bytes, int rw)
699 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
700 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
701 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
704 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
705 uint64_t start_time, uint64_t io_start_time, int rw)
707 struct cfqg_stats *stats = &cfqg->stats;
708 unsigned long long now = sched_clock();
710 if (time_after64(now, io_start_time))
711 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
712 if (time_after64(io_start_time, start_time))
713 blkg_rwstat_add(&stats->wait_time, rw,
714 io_start_time - start_time);
718 static void cfqg_stats_reset(struct cfqg_stats *stats)
720 /* queued stats shouldn't be cleared */
721 blkg_rwstat_reset(&stats->service_bytes);
722 blkg_rwstat_reset(&stats->serviced);
723 blkg_rwstat_reset(&stats->merged);
724 blkg_rwstat_reset(&stats->service_time);
725 blkg_rwstat_reset(&stats->wait_time);
726 blkg_stat_reset(&stats->time);
727 #ifdef CONFIG_DEBUG_BLK_CGROUP
728 blkg_stat_reset(&stats->unaccounted_time);
729 blkg_stat_reset(&stats->avg_queue_size_sum);
730 blkg_stat_reset(&stats->avg_queue_size_samples);
731 blkg_stat_reset(&stats->dequeue);
732 blkg_stat_reset(&stats->group_wait_time);
733 blkg_stat_reset(&stats->idle_time);
734 blkg_stat_reset(&stats->empty_time);
739 static void cfqg_stats_merge(struct cfqg_stats *to, struct cfqg_stats *from)
741 /* queued stats shouldn't be cleared */
742 blkg_rwstat_merge(&to->service_bytes, &from->service_bytes);
743 blkg_rwstat_merge(&to->serviced, &from->serviced);
744 blkg_rwstat_merge(&to->merged, &from->merged);
745 blkg_rwstat_merge(&to->service_time, &from->service_time);
746 blkg_rwstat_merge(&to->wait_time, &from->wait_time);
747 blkg_stat_merge(&from->time, &from->time);
748 #ifdef CONFIG_DEBUG_BLK_CGROUP
749 blkg_stat_merge(&to->unaccounted_time, &from->unaccounted_time);
750 blkg_stat_merge(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
751 blkg_stat_merge(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
752 blkg_stat_merge(&to->dequeue, &from->dequeue);
753 blkg_stat_merge(&to->group_wait_time, &from->group_wait_time);
754 blkg_stat_merge(&to->idle_time, &from->idle_time);
755 blkg_stat_merge(&to->empty_time, &from->empty_time);
760 * Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
761 * recursive stats can still account for the amount used by this cfqg after
764 static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
766 struct cfq_group *parent = cfqg_parent(cfqg);
768 lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
770 if (unlikely(!parent))
773 cfqg_stats_merge(&parent->dead_stats, &cfqg->stats);
774 cfqg_stats_merge(&parent->dead_stats, &cfqg->dead_stats);
775 cfqg_stats_reset(&cfqg->stats);
776 cfqg_stats_reset(&cfqg->dead_stats);
779 #else /* CONFIG_CFQ_GROUP_IOSCHED */
781 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
782 static inline void cfqg_get(struct cfq_group *cfqg) { }
783 static inline void cfqg_put(struct cfq_group *cfqg) { }
785 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
786 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
787 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
788 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
790 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
792 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
793 struct cfq_group *curr_cfqg, int rw) { }
794 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
795 unsigned long time, unsigned long unaccounted_time) { }
796 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
797 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
798 static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
799 uint64_t bytes, int rw) { }
800 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
801 uint64_t start_time, uint64_t io_start_time, int rw) { }
803 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
805 #define cfq_log(cfqd, fmt, args...) \
806 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
808 /* Traverses through cfq group service trees */
809 #define for_each_cfqg_st(cfqg, i, j, st) \
810 for (i = 0; i <= IDLE_WORKLOAD; i++) \
811 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
812 : &cfqg->service_tree_idle; \
813 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
814 (i == IDLE_WORKLOAD && j == 0); \
815 j++, st = i < IDLE_WORKLOAD ? \
816 &cfqg->service_trees[i][j]: NULL) \
818 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
819 struct cfq_ttime *ttime, bool group_idle)
822 if (!sample_valid(ttime->ttime_samples))
825 slice = cfqd->cfq_group_idle;
827 slice = cfqd->cfq_slice_idle;
828 return ttime->ttime_mean > slice;
831 static inline bool iops_mode(struct cfq_data *cfqd)
834 * If we are not idling on queues and it is a NCQ drive, parallel
835 * execution of requests is on and measuring time is not possible
836 * in most of the cases until and unless we drive shallower queue
837 * depths and that becomes a performance bottleneck. In such cases
838 * switch to start providing fairness in terms of number of IOs.
840 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
846 static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
848 if (cfq_class_idle(cfqq))
849 return IDLE_WORKLOAD;
850 if (cfq_class_rt(cfqq))
856 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
858 if (!cfq_cfqq_sync(cfqq))
859 return ASYNC_WORKLOAD;
860 if (!cfq_cfqq_idle_window(cfqq))
861 return SYNC_NOIDLE_WORKLOAD;
862 return SYNC_WORKLOAD;
865 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
866 struct cfq_data *cfqd,
867 struct cfq_group *cfqg)
869 if (wl_class == IDLE_WORKLOAD)
870 return cfqg->service_tree_idle.count;
872 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
873 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
874 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
877 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
878 struct cfq_group *cfqg)
880 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
881 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
884 static void cfq_dispatch_insert(struct request_queue *, struct request *);
885 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
886 struct cfq_io_cq *cic, struct bio *bio);
888 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
890 /* cic->icq is the first member, %NULL will convert to %NULL */
891 return container_of(icq, struct cfq_io_cq, icq);
894 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
895 struct io_context *ioc)
898 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
902 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
904 return cic->cfqq[is_sync];
907 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
910 cic->cfqq[is_sync] = cfqq;
913 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
915 return cic->icq.q->elevator->elevator_data;
919 * We regard a request as SYNC, if it's either a read or has the SYNC bit
920 * set (in which case it could also be direct WRITE).
922 static inline bool cfq_bio_sync(struct bio *bio)
924 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
928 * scheduler run of queue, if there are requests pending and no one in the
929 * driver that will restart queueing
931 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
933 if (cfqd->busy_queues) {
934 cfq_log(cfqd, "schedule dispatch");
935 kblockd_schedule_work(&cfqd->unplug_work);
940 * Scale schedule slice based on io priority. Use the sync time slice only
941 * if a queue is marked sync and has sync io queued. A sync queue with async
942 * io only, should not get full sync slice length.
944 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
947 const int base_slice = cfqd->cfq_slice[sync];
949 WARN_ON(prio >= IOPRIO_BE_NR);
951 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
955 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
957 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
961 * cfqg_scale_charge - scale disk time charge according to cfqg weight
962 * @charge: disk time being charged
963 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
965 * Scale @charge according to @vfraction, which is in range (0, 1]. The
966 * scaling is inversely proportional.
968 * scaled = charge / vfraction
970 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
972 static inline u64 cfqg_scale_charge(unsigned long charge,
973 unsigned int vfraction)
975 u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
977 /* charge / vfraction */
978 c <<= CFQ_SERVICE_SHIFT;
979 do_div(c, vfraction);
983 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
985 s64 delta = (s64)(vdisktime - min_vdisktime);
987 min_vdisktime = vdisktime;
989 return min_vdisktime;
992 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
994 s64 delta = (s64)(vdisktime - min_vdisktime);
996 min_vdisktime = vdisktime;
998 return min_vdisktime;
1001 static void update_min_vdisktime(struct cfq_rb_root *st)
1003 struct cfq_group *cfqg;
1006 cfqg = rb_entry_cfqg(st->left);
1007 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
1013 * get averaged number of queues of RT/BE priority.
1014 * average is updated, with a formula that gives more weight to higher numbers,
1015 * to quickly follows sudden increases and decrease slowly
1018 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1019 struct cfq_group *cfqg, bool rt)
1021 unsigned min_q, max_q;
1022 unsigned mult = cfq_hist_divisor - 1;
1023 unsigned round = cfq_hist_divisor / 2;
1024 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1026 min_q = min(cfqg->busy_queues_avg[rt], busy);
1027 max_q = max(cfqg->busy_queues_avg[rt], busy);
1028 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1030 return cfqg->busy_queues_avg[rt];
1033 static inline unsigned
1034 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1036 return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1039 static inline unsigned
1040 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1042 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
1043 if (cfqd->cfq_latency) {
1045 * interested queues (we consider only the ones with the same
1046 * priority class in the cfq group)
1048 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1049 cfq_class_rt(cfqq));
1050 unsigned sync_slice = cfqd->cfq_slice[1];
1051 unsigned expect_latency = sync_slice * iq;
1052 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1054 if (expect_latency > group_slice) {
1055 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
1056 /* scale low_slice according to IO priority
1057 * and sync vs async */
1058 unsigned low_slice =
1059 min(slice, base_low_slice * slice / sync_slice);
1060 /* the adapted slice value is scaled to fit all iqs
1061 * into the target latency */
1062 slice = max(slice * group_slice / expect_latency,
1070 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1072 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1074 cfqq->slice_start = jiffies;
1075 cfqq->slice_end = jiffies + slice;
1076 cfqq->allocated_slice = slice;
1077 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
1081 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1082 * isn't valid until the first request from the dispatch is activated
1083 * and the slice time set.
1085 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1087 if (cfq_cfqq_slice_new(cfqq))
1089 if (time_before(jiffies, cfqq->slice_end))
1096 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1097 * We choose the request that is closest to the head right now. Distance
1098 * behind the head is penalized and only allowed to a certain extent.
1100 static struct request *
1101 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1103 sector_t s1, s2, d1 = 0, d2 = 0;
1104 unsigned long back_max;
1105 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1106 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1107 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1109 if (rq1 == NULL || rq1 == rq2)
1114 if (rq_is_sync(rq1) != rq_is_sync(rq2))
1115 return rq_is_sync(rq1) ? rq1 : rq2;
1117 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1118 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1120 s1 = blk_rq_pos(rq1);
1121 s2 = blk_rq_pos(rq2);
1124 * by definition, 1KiB is 2 sectors
1126 back_max = cfqd->cfq_back_max * 2;
1129 * Strict one way elevator _except_ in the case where we allow
1130 * short backward seeks which are biased as twice the cost of a
1131 * similar forward seek.
1135 else if (s1 + back_max >= last)
1136 d1 = (last - s1) * cfqd->cfq_back_penalty;
1138 wrap |= CFQ_RQ1_WRAP;
1142 else if (s2 + back_max >= last)
1143 d2 = (last - s2) * cfqd->cfq_back_penalty;
1145 wrap |= CFQ_RQ2_WRAP;
1147 /* Found required data */
1150 * By doing switch() on the bit mask "wrap" we avoid having to
1151 * check two variables for all permutations: --> faster!
1154 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1170 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1173 * Since both rqs are wrapped,
1174 * start with the one that's further behind head
1175 * (--> only *one* back seek required),
1176 * since back seek takes more time than forward.
1186 * The below is leftmost cache rbtree addon
1188 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1190 /* Service tree is empty */
1195 root->left = rb_first(&root->rb);
1198 return rb_entry(root->left, struct cfq_queue, rb_node);
1203 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1206 root->left = rb_first(&root->rb);
1209 return rb_entry_cfqg(root->left);
1214 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1220 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1222 if (root->left == n)
1224 rb_erase_init(n, &root->rb);
1229 * would be nice to take fifo expire time into account as well
1231 static struct request *
1232 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1233 struct request *last)
1235 struct rb_node *rbnext = rb_next(&last->rb_node);
1236 struct rb_node *rbprev = rb_prev(&last->rb_node);
1237 struct request *next = NULL, *prev = NULL;
1239 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1242 prev = rb_entry_rq(rbprev);
1245 next = rb_entry_rq(rbnext);
1247 rbnext = rb_first(&cfqq->sort_list);
1248 if (rbnext && rbnext != &last->rb_node)
1249 next = rb_entry_rq(rbnext);
1252 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1255 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1256 struct cfq_queue *cfqq)
1259 * just an approximation, should be ok.
1261 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1262 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1266 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1268 return cfqg->vdisktime - st->min_vdisktime;
1272 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1274 struct rb_node **node = &st->rb.rb_node;
1275 struct rb_node *parent = NULL;
1276 struct cfq_group *__cfqg;
1277 s64 key = cfqg_key(st, cfqg);
1280 while (*node != NULL) {
1282 __cfqg = rb_entry_cfqg(parent);
1284 if (key < cfqg_key(st, __cfqg))
1285 node = &parent->rb_left;
1287 node = &parent->rb_right;
1293 st->left = &cfqg->rb_node;
1295 rb_link_node(&cfqg->rb_node, parent, node);
1296 rb_insert_color(&cfqg->rb_node, &st->rb);
1300 * This has to be called only on activation of cfqg
1303 cfq_update_group_weight(struct cfq_group *cfqg)
1305 if (cfqg->new_weight) {
1306 cfqg->weight = cfqg->new_weight;
1307 cfqg->new_weight = 0;
1312 cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1314 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1316 if (cfqg->new_leaf_weight) {
1317 cfqg->leaf_weight = cfqg->new_leaf_weight;
1318 cfqg->new_leaf_weight = 0;
1323 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1325 unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
1326 struct cfq_group *pos = cfqg;
1327 struct cfq_group *parent;
1330 /* add to the service tree */
1331 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1334 * Update leaf_weight. We cannot update weight at this point
1335 * because cfqg might already have been activated and is
1336 * contributing its current weight to the parent's child_weight.
1338 cfq_update_group_leaf_weight(cfqg);
1339 __cfq_group_service_tree_add(st, cfqg);
1342 * Activate @cfqg and calculate the portion of vfraction @cfqg is
1343 * entitled to. vfraction is calculated by walking the tree
1344 * towards the root calculating the fraction it has at each level.
1345 * The compounded ratio is how much vfraction @cfqg owns.
1347 * Start with the proportion tasks in this cfqg has against active
1348 * children cfqgs - its leaf_weight against children_weight.
1350 propagate = !pos->nr_active++;
1351 pos->children_weight += pos->leaf_weight;
1352 vfr = vfr * pos->leaf_weight / pos->children_weight;
1355 * Compound ->weight walking up the tree. Both activation and
1356 * vfraction calculation are done in the same loop. Propagation
1357 * stops once an already activated node is met. vfraction
1358 * calculation should always continue to the root.
1360 while ((parent = cfqg_parent(pos))) {
1362 cfq_update_group_weight(pos);
1363 propagate = !parent->nr_active++;
1364 parent->children_weight += pos->weight;
1366 vfr = vfr * pos->weight / parent->children_weight;
1370 cfqg->vfraction = max_t(unsigned, vfr, 1);
1374 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1376 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1377 struct cfq_group *__cfqg;
1381 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1385 * Currently put the group at the end. Later implement something
1386 * so that groups get lesser vtime based on their weights, so that
1387 * if group does not loose all if it was not continuously backlogged.
1389 n = rb_last(&st->rb);
1391 __cfqg = rb_entry_cfqg(n);
1392 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1394 cfqg->vdisktime = st->min_vdisktime;
1395 cfq_group_service_tree_add(st, cfqg);
1399 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1401 struct cfq_group *pos = cfqg;
1405 * Undo activation from cfq_group_service_tree_add(). Deactivate
1406 * @cfqg and propagate deactivation upwards.
1408 propagate = !--pos->nr_active;
1409 pos->children_weight -= pos->leaf_weight;
1412 struct cfq_group *parent = cfqg_parent(pos);
1414 /* @pos has 0 nr_active at this point */
1415 WARN_ON_ONCE(pos->children_weight);
1421 propagate = !--parent->nr_active;
1422 parent->children_weight -= pos->weight;
1426 /* remove from the service tree */
1427 if (!RB_EMPTY_NODE(&cfqg->rb_node))
1428 cfq_rb_erase(&cfqg->rb_node, st);
1432 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1434 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1436 BUG_ON(cfqg->nr_cfqq < 1);
1439 /* If there are other cfq queues under this group, don't delete it */
1443 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1444 cfq_group_service_tree_del(st, cfqg);
1445 cfqg->saved_wl_slice = 0;
1446 cfqg_stats_update_dequeue(cfqg);
1449 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1450 unsigned int *unaccounted_time)
1452 unsigned int slice_used;
1455 * Queue got expired before even a single request completed or
1456 * got expired immediately after first request completion.
1458 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1460 * Also charge the seek time incurred to the group, otherwise
1461 * if there are mutiple queues in the group, each can dispatch
1462 * a single request on seeky media and cause lots of seek time
1463 * and group will never know it.
1465 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1468 slice_used = jiffies - cfqq->slice_start;
1469 if (slice_used > cfqq->allocated_slice) {
1470 *unaccounted_time = slice_used - cfqq->allocated_slice;
1471 slice_used = cfqq->allocated_slice;
1473 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1474 *unaccounted_time += cfqq->slice_start -
1475 cfqq->dispatch_start;
1481 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1482 struct cfq_queue *cfqq)
1484 struct cfq_rb_root *st = &cfqd->grp_service_tree;
1485 unsigned int used_sl, charge, unaccounted_sl = 0;
1486 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1487 - cfqg->service_tree_idle.count;
1490 BUG_ON(nr_sync < 0);
1491 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1493 if (iops_mode(cfqd))
1494 charge = cfqq->slice_dispatch;
1495 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1496 charge = cfqq->allocated_slice;
1499 * Can't update vdisktime while on service tree and cfqg->vfraction
1500 * is valid only while on it. Cache vfr, leave the service tree,
1501 * update vdisktime and go back on. The re-addition to the tree
1502 * will also update the weights as necessary.
1504 vfr = cfqg->vfraction;
1505 cfq_group_service_tree_del(st, cfqg);
1506 cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1507 cfq_group_service_tree_add(st, cfqg);
1509 /* This group is being expired. Save the context */
1510 if (time_after(cfqd->workload_expires, jiffies)) {
1511 cfqg->saved_wl_slice = cfqd->workload_expires
1513 cfqg->saved_wl_type = cfqd->serving_wl_type;
1514 cfqg->saved_wl_class = cfqd->serving_wl_class;
1516 cfqg->saved_wl_slice = 0;
1518 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1520 cfq_log_cfqq(cfqq->cfqd, cfqq,
1521 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1522 used_sl, cfqq->slice_dispatch, charge,
1523 iops_mode(cfqd), cfqq->nr_sectors);
1524 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1525 cfqg_stats_set_start_empty_time(cfqg);
1529 * cfq_init_cfqg_base - initialize base part of a cfq_group
1530 * @cfqg: cfq_group to initialize
1532 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1533 * is enabled or not.
1535 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1537 struct cfq_rb_root *st;
1540 for_each_cfqg_st(cfqg, i, j, st)
1542 RB_CLEAR_NODE(&cfqg->rb_node);
1544 cfqg->ttime.last_end_request = jiffies;
1547 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1548 static void cfqg_stats_init(struct cfqg_stats *stats)
1550 blkg_rwstat_init(&stats->service_bytes);
1551 blkg_rwstat_init(&stats->serviced);
1552 blkg_rwstat_init(&stats->merged);
1553 blkg_rwstat_init(&stats->service_time);
1554 blkg_rwstat_init(&stats->wait_time);
1555 blkg_rwstat_init(&stats->queued);
1557 blkg_stat_init(&stats->sectors);
1558 blkg_stat_init(&stats->time);
1560 #ifdef CONFIG_DEBUG_BLK_CGROUP
1561 blkg_stat_init(&stats->unaccounted_time);
1562 blkg_stat_init(&stats->avg_queue_size_sum);
1563 blkg_stat_init(&stats->avg_queue_size_samples);
1564 blkg_stat_init(&stats->dequeue);
1565 blkg_stat_init(&stats->group_wait_time);
1566 blkg_stat_init(&stats->idle_time);
1567 blkg_stat_init(&stats->empty_time);
1571 static void cfq_cpd_init(const struct blkcg *blkcg)
1573 struct cfq_group_data *cgd =
1574 cpd_to_cfqgd(blkcg->pd[blkcg_policy_cfq.plid]);
1576 if (blkcg == &blkcg_root) {
1577 cgd->weight = 2 * CFQ_WEIGHT_DEFAULT;
1578 cgd->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
1580 cgd->weight = CFQ_WEIGHT_DEFAULT;
1581 cgd->leaf_weight = CFQ_WEIGHT_DEFAULT;
1585 static void cfq_pd_init(struct blkcg_gq *blkg)
1587 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1588 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkg->blkcg);
1590 cfq_init_cfqg_base(cfqg);
1591 cfqg->weight = cgd->weight;
1592 cfqg->leaf_weight = cgd->leaf_weight;
1593 cfqg_stats_init(&cfqg->stats);
1594 cfqg_stats_init(&cfqg->dead_stats);
1597 static void cfq_pd_offline(struct blkcg_gq *blkg)
1600 * @blkg is going offline and will be ignored by
1601 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1602 * that they don't get lost. If IOs complete after this point, the
1603 * stats for them will be lost. Oh well...
1605 cfqg_stats_xfer_dead(blkg_to_cfqg(blkg));
1608 /* offset delta from cfqg->stats to cfqg->dead_stats */
1609 static const int dead_stats_off_delta = offsetof(struct cfq_group, dead_stats) -
1610 offsetof(struct cfq_group, stats);
1612 /* to be used by recursive prfill, sums live and dead stats recursively */
1613 static u64 cfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
1617 sum += blkg_stat_recursive_sum(pd, off);
1618 sum += blkg_stat_recursive_sum(pd, off + dead_stats_off_delta);
1622 /* to be used by recursive prfill, sums live and dead rwstats recursively */
1623 static struct blkg_rwstat cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
1626 struct blkg_rwstat a, b;
1628 a = blkg_rwstat_recursive_sum(pd, off);
1629 b = blkg_rwstat_recursive_sum(pd, off + dead_stats_off_delta);
1630 blkg_rwstat_merge(&a, &b);
1634 static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
1636 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1638 cfqg_stats_reset(&cfqg->stats);
1639 cfqg_stats_reset(&cfqg->dead_stats);
1643 * Search for the cfq group current task belongs to. request_queue lock must
1646 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1647 struct blkcg *blkcg)
1649 struct request_queue *q = cfqd->queue;
1650 struct cfq_group *cfqg = NULL;
1652 /* avoid lookup for the common case where there's no blkcg */
1653 if (blkcg == &blkcg_root) {
1654 cfqg = cfqd->root_group;
1656 struct blkcg_gq *blkg;
1658 blkg = blkg_lookup_create(blkcg, q);
1660 cfqg = blkg_to_cfqg(blkg);
1666 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1668 /* Currently, all async queues are mapped to root group */
1669 if (!cfq_cfqq_sync(cfqq))
1670 cfqg = cfqq->cfqd->root_group;
1673 /* cfqq reference on cfqg */
1677 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1678 struct blkg_policy_data *pd, int off)
1680 struct cfq_group *cfqg = pd_to_cfqg(pd);
1682 if (!cfqg->dev_weight)
1684 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1687 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1689 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1690 cfqg_prfill_weight_device, &blkcg_policy_cfq,
1695 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1696 struct blkg_policy_data *pd, int off)
1698 struct cfq_group *cfqg = pd_to_cfqg(pd);
1700 if (!cfqg->dev_leaf_weight)
1702 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1705 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1707 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1708 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1713 static int cfq_print_weight(struct seq_file *sf, void *v)
1715 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1716 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1717 unsigned int val = 0;
1722 seq_printf(sf, "%u\n", val);
1726 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1728 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1729 struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1730 unsigned int val = 0;
1733 val = cgd->leaf_weight;
1735 seq_printf(sf, "%u\n", val);
1739 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1740 char *buf, size_t nbytes, loff_t off,
1741 bool is_leaf_weight)
1743 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1744 struct blkg_conf_ctx ctx;
1745 struct cfq_group *cfqg;
1746 struct cfq_group_data *cfqgd;
1749 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1754 cfqg = blkg_to_cfqg(ctx.blkg);
1755 cfqgd = blkcg_to_cfqgd(blkcg);
1756 if (!cfqg || !cfqgd)
1759 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1760 if (!is_leaf_weight) {
1761 cfqg->dev_weight = ctx.v;
1762 cfqg->new_weight = ctx.v ?: cfqgd->weight;
1764 cfqg->dev_leaf_weight = ctx.v;
1765 cfqg->new_leaf_weight = ctx.v ?: cfqgd->leaf_weight;
1771 blkg_conf_finish(&ctx);
1772 return ret ?: nbytes;
1775 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1776 char *buf, size_t nbytes, loff_t off)
1778 return __cfqg_set_weight_device(of, buf, nbytes, off, false);
1781 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1782 char *buf, size_t nbytes, loff_t off)
1784 return __cfqg_set_weight_device(of, buf, nbytes, off, true);
1787 static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1788 u64 val, bool is_leaf_weight)
1790 struct blkcg *blkcg = css_to_blkcg(css);
1791 struct blkcg_gq *blkg;
1792 struct cfq_group_data *cfqgd;
1795 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1798 spin_lock_irq(&blkcg->lock);
1799 cfqgd = blkcg_to_cfqgd(blkcg);
1805 if (!is_leaf_weight)
1806 cfqgd->weight = val;
1808 cfqgd->leaf_weight = val;
1810 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1811 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1816 if (!is_leaf_weight) {
1817 if (!cfqg->dev_weight)
1818 cfqg->new_weight = cfqgd->weight;
1820 if (!cfqg->dev_leaf_weight)
1821 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1826 spin_unlock_irq(&blkcg->lock);
1830 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1833 return __cfq_set_weight(css, cft, val, false);
1836 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1837 struct cftype *cft, u64 val)
1839 return __cfq_set_weight(css, cft, val, true);
1842 static int cfqg_print_stat(struct seq_file *sf, void *v)
1844 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1845 &blkcg_policy_cfq, seq_cft(sf)->private, false);
1849 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1851 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1852 &blkcg_policy_cfq, seq_cft(sf)->private, true);
1856 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1857 struct blkg_policy_data *pd, int off)
1859 u64 sum = cfqg_stat_pd_recursive_sum(pd, off);
1861 return __blkg_prfill_u64(sf, pd, sum);
1864 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1865 struct blkg_policy_data *pd, int off)
1867 struct blkg_rwstat sum = cfqg_rwstat_pd_recursive_sum(pd, off);
1869 return __blkg_prfill_rwstat(sf, pd, &sum);
1872 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1874 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1875 cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1876 seq_cft(sf)->private, false);
1880 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1882 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1883 cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1884 seq_cft(sf)->private, true);
1888 #ifdef CONFIG_DEBUG_BLK_CGROUP
1889 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1890 struct blkg_policy_data *pd, int off)
1892 struct cfq_group *cfqg = pd_to_cfqg(pd);
1893 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1897 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1898 v = div64_u64(v, samples);
1900 __blkg_prfill_u64(sf, pd, v);
1904 /* print avg_queue_size */
1905 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1907 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1908 cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1912 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1914 static struct cftype cfq_blkcg_files[] = {
1915 /* on root, weight is mapped to leaf_weight */
1917 .name = "weight_device",
1918 .flags = CFTYPE_ONLY_ON_ROOT,
1919 .seq_show = cfqg_print_leaf_weight_device,
1920 .write = cfqg_set_leaf_weight_device,
1924 .flags = CFTYPE_ONLY_ON_ROOT,
1925 .seq_show = cfq_print_leaf_weight,
1926 .write_u64 = cfq_set_leaf_weight,
1929 /* no such mapping necessary for !roots */
1931 .name = "weight_device",
1932 .flags = CFTYPE_NOT_ON_ROOT,
1933 .seq_show = cfqg_print_weight_device,
1934 .write = cfqg_set_weight_device,
1938 .flags = CFTYPE_NOT_ON_ROOT,
1939 .seq_show = cfq_print_weight,
1940 .write_u64 = cfq_set_weight,
1944 .name = "leaf_weight_device",
1945 .seq_show = cfqg_print_leaf_weight_device,
1946 .write = cfqg_set_leaf_weight_device,
1949 .name = "leaf_weight",
1950 .seq_show = cfq_print_leaf_weight,
1951 .write_u64 = cfq_set_leaf_weight,
1954 /* statistics, covers only the tasks in the cfqg */
1957 .private = offsetof(struct cfq_group, stats.time),
1958 .seq_show = cfqg_print_stat,
1962 .private = offsetof(struct cfq_group, stats.sectors),
1963 .seq_show = cfqg_print_stat,
1966 .name = "io_service_bytes",
1967 .private = offsetof(struct cfq_group, stats.service_bytes),
1968 .seq_show = cfqg_print_rwstat,
1971 .name = "io_serviced",
1972 .private = offsetof(struct cfq_group, stats.serviced),
1973 .seq_show = cfqg_print_rwstat,
1976 .name = "io_service_time",
1977 .private = offsetof(struct cfq_group, stats.service_time),
1978 .seq_show = cfqg_print_rwstat,
1981 .name = "io_wait_time",
1982 .private = offsetof(struct cfq_group, stats.wait_time),
1983 .seq_show = cfqg_print_rwstat,
1986 .name = "io_merged",
1987 .private = offsetof(struct cfq_group, stats.merged),
1988 .seq_show = cfqg_print_rwstat,
1991 .name = "io_queued",
1992 .private = offsetof(struct cfq_group, stats.queued),
1993 .seq_show = cfqg_print_rwstat,
1996 /* the same statictics which cover the cfqg and its descendants */
1998 .name = "time_recursive",
1999 .private = offsetof(struct cfq_group, stats.time),
2000 .seq_show = cfqg_print_stat_recursive,
2003 .name = "sectors_recursive",
2004 .private = offsetof(struct cfq_group, stats.sectors),
2005 .seq_show = cfqg_print_stat_recursive,
2008 .name = "io_service_bytes_recursive",
2009 .private = offsetof(struct cfq_group, stats.service_bytes),
2010 .seq_show = cfqg_print_rwstat_recursive,
2013 .name = "io_serviced_recursive",
2014 .private = offsetof(struct cfq_group, stats.serviced),
2015 .seq_show = cfqg_print_rwstat_recursive,
2018 .name = "io_service_time_recursive",
2019 .private = offsetof(struct cfq_group, stats.service_time),
2020 .seq_show = cfqg_print_rwstat_recursive,
2023 .name = "io_wait_time_recursive",
2024 .private = offsetof(struct cfq_group, stats.wait_time),
2025 .seq_show = cfqg_print_rwstat_recursive,
2028 .name = "io_merged_recursive",
2029 .private = offsetof(struct cfq_group, stats.merged),
2030 .seq_show = cfqg_print_rwstat_recursive,
2033 .name = "io_queued_recursive",
2034 .private = offsetof(struct cfq_group, stats.queued),
2035 .seq_show = cfqg_print_rwstat_recursive,
2037 #ifdef CONFIG_DEBUG_BLK_CGROUP
2039 .name = "avg_queue_size",
2040 .seq_show = cfqg_print_avg_queue_size,
2043 .name = "group_wait_time",
2044 .private = offsetof(struct cfq_group, stats.group_wait_time),
2045 .seq_show = cfqg_print_stat,
2048 .name = "idle_time",
2049 .private = offsetof(struct cfq_group, stats.idle_time),
2050 .seq_show = cfqg_print_stat,
2053 .name = "empty_time",
2054 .private = offsetof(struct cfq_group, stats.empty_time),
2055 .seq_show = cfqg_print_stat,
2059 .private = offsetof(struct cfq_group, stats.dequeue),
2060 .seq_show = cfqg_print_stat,
2063 .name = "unaccounted_time",
2064 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2065 .seq_show = cfqg_print_stat,
2067 #endif /* CONFIG_DEBUG_BLK_CGROUP */
2070 #else /* GROUP_IOSCHED */
2071 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
2072 struct blkcg *blkcg)
2074 return cfqd->root_group;
2078 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2082 #endif /* GROUP_IOSCHED */
2085 * The cfqd->service_trees holds all pending cfq_queue's that have
2086 * requests waiting to be processed. It is sorted in the order that
2087 * we will service the queues.
2089 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2092 struct rb_node **p, *parent;
2093 struct cfq_queue *__cfqq;
2094 unsigned long rb_key;
2095 struct cfq_rb_root *st;
2099 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2100 if (cfq_class_idle(cfqq)) {
2101 rb_key = CFQ_IDLE_DELAY;
2102 parent = rb_last(&st->rb);
2103 if (parent && parent != &cfqq->rb_node) {
2104 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2105 rb_key += __cfqq->rb_key;
2108 } else if (!add_front) {
2110 * Get our rb key offset. Subtract any residual slice
2111 * value carried from last service. A negative resid
2112 * count indicates slice overrun, and this should position
2113 * the next service time further away in the tree.
2115 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
2116 rb_key -= cfqq->slice_resid;
2117 cfqq->slice_resid = 0;
2120 __cfqq = cfq_rb_first(st);
2121 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
2124 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2127 * same position, nothing more to do
2129 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2132 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2133 cfqq->service_tree = NULL;
2138 cfqq->service_tree = st;
2139 p = &st->rb.rb_node;
2142 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2145 * sort by key, that represents service time.
2147 if (time_before(rb_key, __cfqq->rb_key))
2148 p = &parent->rb_left;
2150 p = &parent->rb_right;
2156 st->left = &cfqq->rb_node;
2158 cfqq->rb_key = rb_key;
2159 rb_link_node(&cfqq->rb_node, parent, p);
2160 rb_insert_color(&cfqq->rb_node, &st->rb);
2162 if (add_front || !new_cfqq)
2164 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2167 static struct cfq_queue *
2168 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2169 sector_t sector, struct rb_node **ret_parent,
2170 struct rb_node ***rb_link)
2172 struct rb_node **p, *parent;
2173 struct cfq_queue *cfqq = NULL;
2181 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2184 * Sort strictly based on sector. Smallest to the left,
2185 * largest to the right.
2187 if (sector > blk_rq_pos(cfqq->next_rq))
2188 n = &(*p)->rb_right;
2189 else if (sector < blk_rq_pos(cfqq->next_rq))
2197 *ret_parent = parent;
2203 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2205 struct rb_node **p, *parent;
2206 struct cfq_queue *__cfqq;
2209 rb_erase(&cfqq->p_node, cfqq->p_root);
2210 cfqq->p_root = NULL;
2213 if (cfq_class_idle(cfqq))
2218 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2219 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2220 blk_rq_pos(cfqq->next_rq), &parent, &p);
2222 rb_link_node(&cfqq->p_node, parent, p);
2223 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2225 cfqq->p_root = NULL;
2229 * Update cfqq's position in the service tree.
2231 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2234 * Resorting requires the cfqq to be on the RR list already.
2236 if (cfq_cfqq_on_rr(cfqq)) {
2237 cfq_service_tree_add(cfqd, cfqq, 0);
2238 cfq_prio_tree_add(cfqd, cfqq);
2243 * add to busy list of queues for service, trying to be fair in ordering
2244 * the pending list according to last request service
2246 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2248 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2249 BUG_ON(cfq_cfqq_on_rr(cfqq));
2250 cfq_mark_cfqq_on_rr(cfqq);
2251 cfqd->busy_queues++;
2252 if (cfq_cfqq_sync(cfqq))
2253 cfqd->busy_sync_queues++;
2255 cfq_resort_rr_list(cfqd, cfqq);
2259 * Called when the cfqq no longer has requests pending, remove it from
2262 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2264 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2265 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2266 cfq_clear_cfqq_on_rr(cfqq);
2268 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2269 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2270 cfqq->service_tree = NULL;
2273 rb_erase(&cfqq->p_node, cfqq->p_root);
2274 cfqq->p_root = NULL;
2277 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2278 BUG_ON(!cfqd->busy_queues);
2279 cfqd->busy_queues--;
2280 if (cfq_cfqq_sync(cfqq))
2281 cfqd->busy_sync_queues--;
2285 * rb tree support functions
2287 static void cfq_del_rq_rb(struct request *rq)
2289 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2290 const int sync = rq_is_sync(rq);
2292 BUG_ON(!cfqq->queued[sync]);
2293 cfqq->queued[sync]--;
2295 elv_rb_del(&cfqq->sort_list, rq);
2297 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2299 * Queue will be deleted from service tree when we actually
2300 * expire it later. Right now just remove it from prio tree
2304 rb_erase(&cfqq->p_node, cfqq->p_root);
2305 cfqq->p_root = NULL;
2310 static void cfq_add_rq_rb(struct request *rq)
2312 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2313 struct cfq_data *cfqd = cfqq->cfqd;
2314 struct request *prev;
2316 cfqq->queued[rq_is_sync(rq)]++;
2318 elv_rb_add(&cfqq->sort_list, rq);
2320 if (!cfq_cfqq_on_rr(cfqq))
2321 cfq_add_cfqq_rr(cfqd, cfqq);
2324 * check if this request is a better next-serve candidate
2326 prev = cfqq->next_rq;
2327 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2330 * adjust priority tree position, if ->next_rq changes
2332 if (prev != cfqq->next_rq)
2333 cfq_prio_tree_add(cfqd, cfqq);
2335 BUG_ON(!cfqq->next_rq);
2338 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2340 elv_rb_del(&cfqq->sort_list, rq);
2341 cfqq->queued[rq_is_sync(rq)]--;
2342 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2344 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2348 static struct request *
2349 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2351 struct task_struct *tsk = current;
2352 struct cfq_io_cq *cic;
2353 struct cfq_queue *cfqq;
2355 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2359 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2361 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2366 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2368 struct cfq_data *cfqd = q->elevator->elevator_data;
2370 cfqd->rq_in_driver++;
2371 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2372 cfqd->rq_in_driver);
2374 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2377 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2379 struct cfq_data *cfqd = q->elevator->elevator_data;
2381 WARN_ON(!cfqd->rq_in_driver);
2382 cfqd->rq_in_driver--;
2383 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2384 cfqd->rq_in_driver);
2387 static void cfq_remove_request(struct request *rq)
2389 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2391 if (cfqq->next_rq == rq)
2392 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2394 list_del_init(&rq->queuelist);
2397 cfqq->cfqd->rq_queued--;
2398 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2399 if (rq->cmd_flags & REQ_PRIO) {
2400 WARN_ON(!cfqq->prio_pending);
2401 cfqq->prio_pending--;
2405 static int cfq_merge(struct request_queue *q, struct request **req,
2408 struct cfq_data *cfqd = q->elevator->elevator_data;
2409 struct request *__rq;
2411 __rq = cfq_find_rq_fmerge(cfqd, bio);
2412 if (__rq && elv_rq_merge_ok(__rq, bio)) {
2414 return ELEVATOR_FRONT_MERGE;
2417 return ELEVATOR_NO_MERGE;
2420 static void cfq_merged_request(struct request_queue *q, struct request *req,
2423 if (type == ELEVATOR_FRONT_MERGE) {
2424 struct cfq_queue *cfqq = RQ_CFQQ(req);
2426 cfq_reposition_rq_rb(cfqq, req);
2430 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2433 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
2437 cfq_merged_requests(struct request_queue *q, struct request *rq,
2438 struct request *next)
2440 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2441 struct cfq_data *cfqd = q->elevator->elevator_data;
2444 * reposition in fifo if next is older than rq
2446 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2447 time_before(next->fifo_time, rq->fifo_time) &&
2448 cfqq == RQ_CFQQ(next)) {
2449 list_move(&rq->queuelist, &next->queuelist);
2450 rq->fifo_time = next->fifo_time;
2453 if (cfqq->next_rq == next)
2455 cfq_remove_request(next);
2456 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2458 cfqq = RQ_CFQQ(next);
2460 * all requests of this queue are merged to other queues, delete it
2461 * from the service tree. If it's the active_queue,
2462 * cfq_dispatch_requests() will choose to expire it or do idle
2464 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2465 cfqq != cfqd->active_queue)
2466 cfq_del_cfqq_rr(cfqd, cfqq);
2469 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
2472 struct cfq_data *cfqd = q->elevator->elevator_data;
2473 struct cfq_io_cq *cic;
2474 struct cfq_queue *cfqq;
2477 * Disallow merge of a sync bio into an async request.
2479 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2483 * Lookup the cfqq that this bio will be queued with and allow
2484 * merge only if rq is queued there.
2486 cic = cfq_cic_lookup(cfqd, current->io_context);
2490 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2491 return cfqq == RQ_CFQQ(rq);
2494 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2496 del_timer(&cfqd->idle_slice_timer);
2497 cfqg_stats_update_idle_time(cfqq->cfqg);
2500 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2501 struct cfq_queue *cfqq)
2504 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2505 cfqd->serving_wl_class, cfqd->serving_wl_type);
2506 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2507 cfqq->slice_start = 0;
2508 cfqq->dispatch_start = jiffies;
2509 cfqq->allocated_slice = 0;
2510 cfqq->slice_end = 0;
2511 cfqq->slice_dispatch = 0;
2512 cfqq->nr_sectors = 0;
2514 cfq_clear_cfqq_wait_request(cfqq);
2515 cfq_clear_cfqq_must_dispatch(cfqq);
2516 cfq_clear_cfqq_must_alloc_slice(cfqq);
2517 cfq_clear_cfqq_fifo_expire(cfqq);
2518 cfq_mark_cfqq_slice_new(cfqq);
2520 cfq_del_timer(cfqd, cfqq);
2523 cfqd->active_queue = cfqq;
2527 * current cfqq expired its slice (or was too idle), select new one
2530 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2533 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2535 if (cfq_cfqq_wait_request(cfqq))
2536 cfq_del_timer(cfqd, cfqq);
2538 cfq_clear_cfqq_wait_request(cfqq);
2539 cfq_clear_cfqq_wait_busy(cfqq);
2542 * If this cfqq is shared between multiple processes, check to
2543 * make sure that those processes are still issuing I/Os within
2544 * the mean seek distance. If not, it may be time to break the
2545 * queues apart again.
2547 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2548 cfq_mark_cfqq_split_coop(cfqq);
2551 * store what was left of this slice, if the queue idled/timed out
2554 if (cfq_cfqq_slice_new(cfqq))
2555 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2557 cfqq->slice_resid = cfqq->slice_end - jiffies;
2558 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2561 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2563 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2564 cfq_del_cfqq_rr(cfqd, cfqq);
2566 cfq_resort_rr_list(cfqd, cfqq);
2568 if (cfqq == cfqd->active_queue)
2569 cfqd->active_queue = NULL;
2571 if (cfqd->active_cic) {
2572 put_io_context(cfqd->active_cic->icq.ioc);
2573 cfqd->active_cic = NULL;
2577 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2579 struct cfq_queue *cfqq = cfqd->active_queue;
2582 __cfq_slice_expired(cfqd, cfqq, timed_out);
2586 * Get next queue for service. Unless we have a queue preemption,
2587 * we'll simply select the first cfqq in the service tree.
2589 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2591 struct cfq_rb_root *st = st_for(cfqd->serving_group,
2592 cfqd->serving_wl_class, cfqd->serving_wl_type);
2594 if (!cfqd->rq_queued)
2597 /* There is nothing to dispatch */
2600 if (RB_EMPTY_ROOT(&st->rb))
2602 return cfq_rb_first(st);
2605 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2607 struct cfq_group *cfqg;
2608 struct cfq_queue *cfqq;
2610 struct cfq_rb_root *st;
2612 if (!cfqd->rq_queued)
2615 cfqg = cfq_get_next_cfqg(cfqd);
2619 for_each_cfqg_st(cfqg, i, j, st)
2620 if ((cfqq = cfq_rb_first(st)) != NULL)
2626 * Get and set a new active queue for service.
2628 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2629 struct cfq_queue *cfqq)
2632 cfqq = cfq_get_next_queue(cfqd);
2634 __cfq_set_active_queue(cfqd, cfqq);
2638 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2641 if (blk_rq_pos(rq) >= cfqd->last_position)
2642 return blk_rq_pos(rq) - cfqd->last_position;
2644 return cfqd->last_position - blk_rq_pos(rq);
2647 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2650 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2653 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2654 struct cfq_queue *cur_cfqq)
2656 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2657 struct rb_node *parent, *node;
2658 struct cfq_queue *__cfqq;
2659 sector_t sector = cfqd->last_position;
2661 if (RB_EMPTY_ROOT(root))
2665 * First, if we find a request starting at the end of the last
2666 * request, choose it.
2668 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2673 * If the exact sector wasn't found, the parent of the NULL leaf
2674 * will contain the closest sector.
2676 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2677 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2680 if (blk_rq_pos(__cfqq->next_rq) < sector)
2681 node = rb_next(&__cfqq->p_node);
2683 node = rb_prev(&__cfqq->p_node);
2687 __cfqq = rb_entry(node, struct cfq_queue, p_node);
2688 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2696 * cur_cfqq - passed in so that we don't decide that the current queue is
2697 * closely cooperating with itself.
2699 * So, basically we're assuming that that cur_cfqq has dispatched at least
2700 * one request, and that cfqd->last_position reflects a position on the disk
2701 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2704 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2705 struct cfq_queue *cur_cfqq)
2707 struct cfq_queue *cfqq;
2709 if (cfq_class_idle(cur_cfqq))
2711 if (!cfq_cfqq_sync(cur_cfqq))
2713 if (CFQQ_SEEKY(cur_cfqq))
2717 * Don't search priority tree if it's the only queue in the group.
2719 if (cur_cfqq->cfqg->nr_cfqq == 1)
2723 * We should notice if some of the queues are cooperating, eg
2724 * working closely on the same area of the disk. In that case,
2725 * we can group them together and don't waste time idling.
2727 cfqq = cfqq_close(cfqd, cur_cfqq);
2731 /* If new queue belongs to different cfq_group, don't choose it */
2732 if (cur_cfqq->cfqg != cfqq->cfqg)
2736 * It only makes sense to merge sync queues.
2738 if (!cfq_cfqq_sync(cfqq))
2740 if (CFQQ_SEEKY(cfqq))
2744 * Do not merge queues of different priority classes
2746 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2753 * Determine whether we should enforce idle window for this queue.
2756 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2758 enum wl_class_t wl_class = cfqq_class(cfqq);
2759 struct cfq_rb_root *st = cfqq->service_tree;
2764 if (!cfqd->cfq_slice_idle)
2767 /* We never do for idle class queues. */
2768 if (wl_class == IDLE_WORKLOAD)
2771 /* We do for queues that were marked with idle window flag. */
2772 if (cfq_cfqq_idle_window(cfqq) &&
2773 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2777 * Otherwise, we do only if they are the last ones
2778 * in their service tree.
2780 if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2781 !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2783 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2787 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2789 struct cfq_queue *cfqq = cfqd->active_queue;
2790 struct cfq_io_cq *cic;
2791 unsigned long sl, group_idle = 0;
2794 * SSD device without seek penalty, disable idling. But only do so
2795 * for devices that support queuing, otherwise we still have a problem
2796 * with sync vs async workloads.
2798 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2801 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2802 WARN_ON(cfq_cfqq_slice_new(cfqq));
2805 * idle is disabled, either manually or by past process history
2807 if (!cfq_should_idle(cfqd, cfqq)) {
2808 /* no queue idling. Check for group idling */
2809 if (cfqd->cfq_group_idle)
2810 group_idle = cfqd->cfq_group_idle;
2816 * still active requests from this queue, don't idle
2818 if (cfqq->dispatched)
2822 * task has exited, don't wait
2824 cic = cfqd->active_cic;
2825 if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2829 * If our average think time is larger than the remaining time
2830 * slice, then don't idle. This avoids overrunning the allotted
2833 if (sample_valid(cic->ttime.ttime_samples) &&
2834 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2835 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2836 cic->ttime.ttime_mean);
2840 /* There are other queues in the group, don't do group idle */
2841 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2844 cfq_mark_cfqq_wait_request(cfqq);
2847 sl = cfqd->cfq_group_idle;
2849 sl = cfqd->cfq_slice_idle;
2851 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2852 cfqg_stats_set_start_idle_time(cfqq->cfqg);
2853 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2854 group_idle ? 1 : 0);
2858 * Move request from internal lists to the request queue dispatch list.
2860 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2862 struct cfq_data *cfqd = q->elevator->elevator_data;
2863 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2865 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2867 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2868 cfq_remove_request(rq);
2870 (RQ_CFQG(rq))->dispatched++;
2871 elv_dispatch_sort(q, rq);
2873 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2874 cfqq->nr_sectors += blk_rq_sectors(rq);
2875 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2879 * return expired entry, or NULL to just start from scratch in rbtree
2881 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2883 struct request *rq = NULL;
2885 if (cfq_cfqq_fifo_expire(cfqq))
2888 cfq_mark_cfqq_fifo_expire(cfqq);
2890 if (list_empty(&cfqq->fifo))
2893 rq = rq_entry_fifo(cfqq->fifo.next);
2894 if (time_before(jiffies, rq->fifo_time))
2897 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2902 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2904 const int base_rq = cfqd->cfq_slice_async_rq;
2906 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2908 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2912 * Must be called with the queue_lock held.
2914 static int cfqq_process_refs(struct cfq_queue *cfqq)
2916 int process_refs, io_refs;
2918 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2919 process_refs = cfqq->ref - io_refs;
2920 BUG_ON(process_refs < 0);
2921 return process_refs;
2924 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2926 int process_refs, new_process_refs;
2927 struct cfq_queue *__cfqq;
2930 * If there are no process references on the new_cfqq, then it is
2931 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2932 * chain may have dropped their last reference (not just their
2933 * last process reference).
2935 if (!cfqq_process_refs(new_cfqq))
2938 /* Avoid a circular list and skip interim queue merges */
2939 while ((__cfqq = new_cfqq->new_cfqq)) {
2945 process_refs = cfqq_process_refs(cfqq);
2946 new_process_refs = cfqq_process_refs(new_cfqq);
2948 * If the process for the cfqq has gone away, there is no
2949 * sense in merging the queues.
2951 if (process_refs == 0 || new_process_refs == 0)
2955 * Merge in the direction of the lesser amount of work.
2957 if (new_process_refs >= process_refs) {
2958 cfqq->new_cfqq = new_cfqq;
2959 new_cfqq->ref += process_refs;
2961 new_cfqq->new_cfqq = cfqq;
2962 cfqq->ref += new_process_refs;
2966 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
2967 struct cfq_group *cfqg, enum wl_class_t wl_class)
2969 struct cfq_queue *queue;
2971 bool key_valid = false;
2972 unsigned long lowest_key = 0;
2973 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2975 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2976 /* select the one with lowest rb_key */
2977 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
2979 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2980 lowest_key = queue->rb_key;
2990 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
2994 struct cfq_rb_root *st;
2995 unsigned group_slice;
2996 enum wl_class_t original_class = cfqd->serving_wl_class;
2998 /* Choose next priority. RT > BE > IDLE */
2999 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3000 cfqd->serving_wl_class = RT_WORKLOAD;
3001 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3002 cfqd->serving_wl_class = BE_WORKLOAD;
3004 cfqd->serving_wl_class = IDLE_WORKLOAD;
3005 cfqd->workload_expires = jiffies + 1;
3009 if (original_class != cfqd->serving_wl_class)
3013 * For RT and BE, we have to choose also the type
3014 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3017 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3021 * check workload expiration, and that we still have other queues ready
3023 if (count && !time_after(jiffies, cfqd->workload_expires))
3027 /* otherwise select new workload type */
3028 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3029 cfqd->serving_wl_class);
3030 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3034 * the workload slice is computed as a fraction of target latency
3035 * proportional to the number of queues in that workload, over
3036 * all the queues in the same priority class
3038 group_slice = cfq_group_slice(cfqd, cfqg);
3040 slice = group_slice * count /
3041 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3042 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3045 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3049 * Async queues are currently system wide. Just taking
3050 * proportion of queues with-in same group will lead to higher
3051 * async ratio system wide as generally root group is going
3052 * to have higher weight. A more accurate thing would be to
3053 * calculate system wide asnc/sync ratio.
3055 tmp = cfqd->cfq_target_latency *
3056 cfqg_busy_async_queues(cfqd, cfqg);
3057 tmp = tmp/cfqd->busy_queues;
3058 slice = min_t(unsigned, slice, tmp);
3060 /* async workload slice is scaled down according to
3061 * the sync/async slice ratio. */
3062 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
3064 /* sync workload slice is at least 2 * cfq_slice_idle */
3065 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3067 slice = max_t(unsigned, slice, CFQ_MIN_TT);
3068 cfq_log(cfqd, "workload slice:%d", slice);
3069 cfqd->workload_expires = jiffies + slice;
3072 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3074 struct cfq_rb_root *st = &cfqd->grp_service_tree;
3075 struct cfq_group *cfqg;
3077 if (RB_EMPTY_ROOT(&st->rb))
3079 cfqg = cfq_rb_first_group(st);
3080 update_min_vdisktime(st);
3084 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3086 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3088 cfqd->serving_group = cfqg;
3090 /* Restore the workload type data */
3091 if (cfqg->saved_wl_slice) {
3092 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
3093 cfqd->serving_wl_type = cfqg->saved_wl_type;
3094 cfqd->serving_wl_class = cfqg->saved_wl_class;
3096 cfqd->workload_expires = jiffies - 1;
3098 choose_wl_class_and_type(cfqd, cfqg);
3102 * Select a queue for service. If we have a current active queue,
3103 * check whether to continue servicing it, or retrieve and set a new one.
3105 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3107 struct cfq_queue *cfqq, *new_cfqq = NULL;
3109 cfqq = cfqd->active_queue;
3113 if (!cfqd->rq_queued)
3117 * We were waiting for group to get backlogged. Expire the queue
3119 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3123 * The active queue has run out of time, expire it and select new.
3125 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3127 * If slice had not expired at the completion of last request
3128 * we might not have turned on wait_busy flag. Don't expire
3129 * the queue yet. Allow the group to get backlogged.
3131 * The very fact that we have used the slice, that means we
3132 * have been idling all along on this queue and it should be
3133 * ok to wait for this request to complete.
3135 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3136 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3140 goto check_group_idle;
3144 * The active queue has requests and isn't expired, allow it to
3147 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3151 * If another queue has a request waiting within our mean seek
3152 * distance, let it run. The expire code will check for close
3153 * cooperators and put the close queue at the front of the service
3154 * tree. If possible, merge the expiring queue with the new cfqq.
3156 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3158 if (!cfqq->new_cfqq)
3159 cfq_setup_merge(cfqq, new_cfqq);
3164 * No requests pending. If the active queue still has requests in
3165 * flight or is idling for a new request, allow either of these
3166 * conditions to happen (or time out) before selecting a new queue.
3168 if (timer_pending(&cfqd->idle_slice_timer)) {
3174 * This is a deep seek queue, but the device is much faster than
3175 * the queue can deliver, don't idle
3177 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3178 (cfq_cfqq_slice_new(cfqq) ||
3179 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
3180 cfq_clear_cfqq_deep(cfqq);
3181 cfq_clear_cfqq_idle_window(cfqq);
3184 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3190 * If group idle is enabled and there are requests dispatched from
3191 * this group, wait for requests to complete.
3194 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3195 cfqq->cfqg->dispatched &&
3196 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3202 cfq_slice_expired(cfqd, 0);
3205 * Current queue expired. Check if we have to switch to a new
3209 cfq_choose_cfqg(cfqd);
3211 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3216 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3220 while (cfqq->next_rq) {
3221 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3225 BUG_ON(!list_empty(&cfqq->fifo));
3227 /* By default cfqq is not expired if it is empty. Do it explicitly */
3228 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3233 * Drain our current requests. Used for barriers and when switching
3234 * io schedulers on-the-fly.
3236 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3238 struct cfq_queue *cfqq;
3241 /* Expire the timeslice of the current active queue first */
3242 cfq_slice_expired(cfqd, 0);
3243 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3244 __cfq_set_active_queue(cfqd, cfqq);
3245 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3248 BUG_ON(cfqd->busy_queues);
3250 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3254 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3255 struct cfq_queue *cfqq)
3257 /* the queue hasn't finished any request, can't estimate */
3258 if (cfq_cfqq_slice_new(cfqq))
3260 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
3267 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3269 unsigned int max_dispatch;
3272 * Drain async requests before we start sync IO
3274 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3278 * If this is an async queue and we have sync IO in flight, let it wait
3280 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3283 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3284 if (cfq_class_idle(cfqq))
3288 * Does this cfqq already have too much IO in flight?
3290 if (cfqq->dispatched >= max_dispatch) {
3291 bool promote_sync = false;
3293 * idle queue must always only have a single IO in flight
3295 if (cfq_class_idle(cfqq))
3299 * If there is only one sync queue
3300 * we can ignore async queue here and give the sync
3301 * queue no dispatch limit. The reason is a sync queue can
3302 * preempt async queue, limiting the sync queue doesn't make
3303 * sense. This is useful for aiostress test.
3305 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3306 promote_sync = true;
3309 * We have other queues, don't allow more IO from this one
3311 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3316 * Sole queue user, no limit
3318 if (cfqd->busy_queues == 1 || promote_sync)
3322 * Normally we start throttling cfqq when cfq_quantum/2
3323 * requests have been dispatched. But we can drive
3324 * deeper queue depths at the beginning of slice
3325 * subjected to upper limit of cfq_quantum.
3327 max_dispatch = cfqd->cfq_quantum;
3331 * Async queues must wait a bit before being allowed dispatch.
3332 * We also ramp up the dispatch depth gradually for async IO,
3333 * based on the last sync IO we serviced
3335 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3336 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
3339 depth = last_sync / cfqd->cfq_slice[1];
3340 if (!depth && !cfqq->dispatched)
3342 if (depth < max_dispatch)
3343 max_dispatch = depth;
3347 * If we're below the current max, allow a dispatch
3349 return cfqq->dispatched < max_dispatch;
3353 * Dispatch a request from cfqq, moving them to the request queue
3356 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3360 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3362 if (!cfq_may_dispatch(cfqd, cfqq))
3366 * follow expired path, else get first next available
3368 rq = cfq_check_fifo(cfqq);
3373 * insert request into driver dispatch list
3375 cfq_dispatch_insert(cfqd->queue, rq);
3377 if (!cfqd->active_cic) {
3378 struct cfq_io_cq *cic = RQ_CIC(rq);
3380 atomic_long_inc(&cic->icq.ioc->refcount);
3381 cfqd->active_cic = cic;
3388 * Find the cfqq that we need to service and move a request from that to the
3391 static int cfq_dispatch_requests(struct request_queue *q, int force)
3393 struct cfq_data *cfqd = q->elevator->elevator_data;
3394 struct cfq_queue *cfqq;
3396 if (!cfqd->busy_queues)
3399 if (unlikely(force))
3400 return cfq_forced_dispatch(cfqd);
3402 cfqq = cfq_select_queue(cfqd);
3407 * Dispatch a request from this cfqq, if it is allowed
3409 if (!cfq_dispatch_request(cfqd, cfqq))
3412 cfqq->slice_dispatch++;
3413 cfq_clear_cfqq_must_dispatch(cfqq);
3416 * expire an async queue immediately if it has used up its slice. idle
3417 * queue always expire after 1 dispatch round.
3419 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3420 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3421 cfq_class_idle(cfqq))) {
3422 cfqq->slice_end = jiffies + 1;
3423 cfq_slice_expired(cfqd, 0);
3426 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3431 * task holds one reference to the queue, dropped when task exits. each rq
3432 * in-flight on this queue also holds a reference, dropped when rq is freed.
3434 * Each cfq queue took a reference on the parent group. Drop it now.
3435 * queue lock must be held here.
3437 static void cfq_put_queue(struct cfq_queue *cfqq)
3439 struct cfq_data *cfqd = cfqq->cfqd;
3440 struct cfq_group *cfqg;
3442 BUG_ON(cfqq->ref <= 0);
3448 cfq_log_cfqq(cfqd, cfqq, "put_queue");
3449 BUG_ON(rb_first(&cfqq->sort_list));
3450 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3453 if (unlikely(cfqd->active_queue == cfqq)) {
3454 __cfq_slice_expired(cfqd, cfqq, 0);
3455 cfq_schedule_dispatch(cfqd);
3458 BUG_ON(cfq_cfqq_on_rr(cfqq));
3459 kmem_cache_free(cfq_pool, cfqq);
3463 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3465 struct cfq_queue *__cfqq, *next;
3468 * If this queue was scheduled to merge with another queue, be
3469 * sure to drop the reference taken on that queue (and others in
3470 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3472 __cfqq = cfqq->new_cfqq;
3474 if (__cfqq == cfqq) {
3475 WARN(1, "cfqq->new_cfqq loop detected\n");
3478 next = __cfqq->new_cfqq;
3479 cfq_put_queue(__cfqq);
3484 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3486 if (unlikely(cfqq == cfqd->active_queue)) {
3487 __cfq_slice_expired(cfqd, cfqq, 0);
3488 cfq_schedule_dispatch(cfqd);
3491 cfq_put_cooperator(cfqq);
3493 cfq_put_queue(cfqq);
3496 static void cfq_init_icq(struct io_cq *icq)
3498 struct cfq_io_cq *cic = icq_to_cic(icq);
3500 cic->ttime.last_end_request = jiffies;
3503 static void cfq_exit_icq(struct io_cq *icq)
3505 struct cfq_io_cq *cic = icq_to_cic(icq);
3506 struct cfq_data *cfqd = cic_to_cfqd(cic);
3508 if (cic_to_cfqq(cic, false)) {
3509 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3510 cic_set_cfqq(cic, NULL, false);
3513 if (cic_to_cfqq(cic, true)) {
3514 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3515 cic_set_cfqq(cic, NULL, true);
3519 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3521 struct task_struct *tsk = current;
3524 if (!cfq_cfqq_prio_changed(cfqq))
3527 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3528 switch (ioprio_class) {
3530 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3531 case IOPRIO_CLASS_NONE:
3533 * no prio set, inherit CPU scheduling settings
3535 cfqq->ioprio = task_nice_ioprio(tsk);
3536 cfqq->ioprio_class = task_nice_ioclass(tsk);
3538 case IOPRIO_CLASS_RT:
3539 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3540 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3542 case IOPRIO_CLASS_BE:
3543 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3544 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3546 case IOPRIO_CLASS_IDLE:
3547 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3549 cfq_clear_cfqq_idle_window(cfqq);
3554 * keep track of original prio settings in case we have to temporarily
3555 * elevate the priority of this queue
3557 cfqq->org_ioprio = cfqq->ioprio;
3558 cfq_clear_cfqq_prio_changed(cfqq);
3561 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3563 int ioprio = cic->icq.ioc->ioprio;
3564 struct cfq_data *cfqd = cic_to_cfqd(cic);
3565 struct cfq_queue *cfqq;
3568 * Check whether ioprio has changed. The condition may trigger
3569 * spuriously on a newly created cic but there's no harm.
3571 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3574 cfqq = cic_to_cfqq(cic, false);
3576 cfq_put_queue(cfqq);
3577 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3578 cic_set_cfqq(cic, cfqq, false);
3581 cfqq = cic_to_cfqq(cic, true);
3583 cfq_mark_cfqq_prio_changed(cfqq);
3585 cic->ioprio = ioprio;
3588 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3589 pid_t pid, bool is_sync)
3591 RB_CLEAR_NODE(&cfqq->rb_node);
3592 RB_CLEAR_NODE(&cfqq->p_node);
3593 INIT_LIST_HEAD(&cfqq->fifo);
3598 cfq_mark_cfqq_prio_changed(cfqq);
3601 if (!cfq_class_idle(cfqq))
3602 cfq_mark_cfqq_idle_window(cfqq);
3603 cfq_mark_cfqq_sync(cfqq);
3608 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3609 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3611 struct cfq_data *cfqd = cic_to_cfqd(cic);
3612 struct cfq_queue *sync_cfqq;
3616 serial_nr = bio_blkcg(bio)->css.serial_nr;
3620 * Check whether blkcg has changed. The condition may trigger
3621 * spuriously on a newly created cic but there's no harm.
3623 if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3626 sync_cfqq = cic_to_cfqq(cic, 1);
3629 * Drop reference to sync queue. A new sync queue will be
3630 * assigned in new group upon arrival of a fresh request.
3632 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3633 cic_set_cfqq(cic, NULL, 1);
3634 cfq_put_queue(sync_cfqq);
3637 cic->blkcg_serial_nr = serial_nr;
3640 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3641 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3643 static struct cfq_queue *
3644 cfq_find_alloc_queue(struct cfq_data *cfqd, struct cfq_group *cfqg, bool is_sync,
3645 struct cfq_io_cq *cic, struct bio *bio)
3647 struct cfq_queue *cfqq;
3649 cfqq = cic_to_cfqq(cic, is_sync);
3652 * Always try a new alloc if we fell back to the OOM cfqq
3653 * originally, since it should just be a temporary situation.
3655 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3656 cfqq = kmem_cache_alloc_node(cfq_pool,
3657 GFP_NOWAIT | __GFP_ZERO,
3660 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3661 cfq_init_prio_data(cfqq, cic);
3662 cfq_link_cfqq_cfqg(cfqq, cfqg);
3663 cfq_log_cfqq(cfqd, cfqq, "alloced");
3665 cfqq = &cfqd->oom_cfqq;
3670 static struct cfq_queue **
3671 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3673 switch (ioprio_class) {
3674 case IOPRIO_CLASS_RT:
3675 return &cfqd->async_cfqq[0][ioprio];
3676 case IOPRIO_CLASS_NONE:
3677 ioprio = IOPRIO_NORM;
3679 case IOPRIO_CLASS_BE:
3680 return &cfqd->async_cfqq[1][ioprio];
3681 case IOPRIO_CLASS_IDLE:
3682 return &cfqd->async_idle_cfqq;
3688 static struct cfq_queue *
3689 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3692 int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3693 int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3694 struct cfq_queue **async_cfqq;
3695 struct cfq_queue *cfqq;
3696 struct cfq_group *cfqg;
3699 cfqg = cfq_lookup_create_cfqg(cfqd, bio_blkcg(bio));
3701 cfqq = &cfqd->oom_cfqq;
3706 if (!ioprio_valid(cic->ioprio)) {
3707 struct task_struct *tsk = current;
3708 ioprio = task_nice_ioprio(tsk);
3709 ioprio_class = task_nice_ioclass(tsk);
3711 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3717 cfqq = cfq_find_alloc_queue(cfqd, cfqg, is_sync, cic, bio);
3720 * pin the queue now that it's allocated, scheduler exit will prune it
3722 if (!is_sync && cfqq != &cfqd->oom_cfqq) {
3733 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3735 unsigned long elapsed = jiffies - ttime->last_end_request;
3736 elapsed = min(elapsed, 2UL * slice_idle);
3738 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3739 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3740 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3744 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3745 struct cfq_io_cq *cic)
3747 if (cfq_cfqq_sync(cfqq)) {
3748 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3749 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3750 cfqd->cfq_slice_idle);
3752 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3753 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3758 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3762 sector_t n_sec = blk_rq_sectors(rq);
3763 if (cfqq->last_request_pos) {
3764 if (cfqq->last_request_pos < blk_rq_pos(rq))
3765 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3767 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3770 cfqq->seek_history <<= 1;
3771 if (blk_queue_nonrot(cfqd->queue))
3772 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3774 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3778 * Disable idle window if the process thinks too long or seeks so much that
3782 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3783 struct cfq_io_cq *cic)
3785 int old_idle, enable_idle;
3788 * Don't idle for async or idle io prio class
3790 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3793 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3795 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3796 cfq_mark_cfqq_deep(cfqq);
3798 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3800 else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3801 !cfqd->cfq_slice_idle ||
3802 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3804 else if (sample_valid(cic->ttime.ttime_samples)) {
3805 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3811 if (old_idle != enable_idle) {
3812 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3814 cfq_mark_cfqq_idle_window(cfqq);
3816 cfq_clear_cfqq_idle_window(cfqq);
3821 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3822 * no or if we aren't sure, a 1 will cause a preempt.
3825 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3828 struct cfq_queue *cfqq;
3830 cfqq = cfqd->active_queue;
3834 if (cfq_class_idle(new_cfqq))
3837 if (cfq_class_idle(cfqq))
3841 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3843 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3847 * if the new request is sync, but the currently running queue is
3848 * not, let the sync request have priority.
3850 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3853 if (new_cfqq->cfqg != cfqq->cfqg)
3856 if (cfq_slice_used(cfqq))
3859 /* Allow preemption only if we are idling on sync-noidle tree */
3860 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
3861 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3862 new_cfqq->service_tree->count == 2 &&
3863 RB_EMPTY_ROOT(&cfqq->sort_list))
3867 * So both queues are sync. Let the new request get disk time if
3868 * it's a metadata request and the current queue is doing regular IO.
3870 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3874 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3876 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3879 /* An idle queue should not be idle now for some reason */
3880 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3883 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3887 * if this request is as-good as one we would expect from the
3888 * current cfqq, let it preempt
3890 if (cfq_rq_close(cfqd, cfqq, rq))
3897 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3898 * let it have half of its nominal slice.
3900 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3902 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3904 cfq_log_cfqq(cfqd, cfqq, "preempt");
3905 cfq_slice_expired(cfqd, 1);
3908 * workload type is changed, don't save slice, otherwise preempt
3911 if (old_type != cfqq_type(cfqq))
3912 cfqq->cfqg->saved_wl_slice = 0;
3915 * Put the new queue at the front of the of the current list,
3916 * so we know that it will be selected next.
3918 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3920 cfq_service_tree_add(cfqd, cfqq, 1);
3922 cfqq->slice_end = 0;
3923 cfq_mark_cfqq_slice_new(cfqq);
3927 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3928 * something we should do about it
3931 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3934 struct cfq_io_cq *cic = RQ_CIC(rq);
3937 if (rq->cmd_flags & REQ_PRIO)
3938 cfqq->prio_pending++;
3940 cfq_update_io_thinktime(cfqd, cfqq, cic);
3941 cfq_update_io_seektime(cfqd, cfqq, rq);
3942 cfq_update_idle_window(cfqd, cfqq, cic);
3944 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3946 if (cfqq == cfqd->active_queue) {
3948 * Remember that we saw a request from this process, but
3949 * don't start queuing just yet. Otherwise we risk seeing lots
3950 * of tiny requests, because we disrupt the normal plugging
3951 * and merging. If the request is already larger than a single
3952 * page, let it rip immediately. For that case we assume that
3953 * merging is already done. Ditto for a busy system that
3954 * has other work pending, don't risk delaying until the
3955 * idle timer unplug to continue working.
3957 if (cfq_cfqq_wait_request(cfqq)) {
3958 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3959 cfqd->busy_queues > 1) {
3960 cfq_del_timer(cfqd, cfqq);
3961 cfq_clear_cfqq_wait_request(cfqq);
3962 __blk_run_queue(cfqd->queue);
3964 cfqg_stats_update_idle_time(cfqq->cfqg);
3965 cfq_mark_cfqq_must_dispatch(cfqq);
3968 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3970 * not the active queue - expire current slice if it is
3971 * idle and has expired it's mean thinktime or this new queue
3972 * has some old slice time left and is of higher priority or
3973 * this new queue is RT and the current one is BE
3975 cfq_preempt_queue(cfqd, cfqq);
3976 __blk_run_queue(cfqd->queue);
3980 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3982 struct cfq_data *cfqd = q->elevator->elevator_data;
3983 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3985 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3986 cfq_init_prio_data(cfqq, RQ_CIC(rq));
3988 rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
3989 list_add_tail(&rq->queuelist, &cfqq->fifo);
3991 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3993 cfq_rq_enqueued(cfqd, cfqq, rq);
3997 * Update hw_tag based on peak queue depth over 50 samples under
4000 static void cfq_update_hw_tag(struct cfq_data *cfqd)
4002 struct cfq_queue *cfqq = cfqd->active_queue;
4004 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
4005 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
4007 if (cfqd->hw_tag == 1)
4010 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
4011 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
4015 * If active queue hasn't enough requests and can idle, cfq might not
4016 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4019 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4020 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4021 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4024 if (cfqd->hw_tag_samples++ < 50)
4027 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4033 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4035 struct cfq_io_cq *cic = cfqd->active_cic;
4037 /* If the queue already has requests, don't wait */
4038 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4041 /* If there are other queues in the group, don't wait */
4042 if (cfqq->cfqg->nr_cfqq > 1)
4045 /* the only queue in the group, but think time is big */
4046 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4049 if (cfq_slice_used(cfqq))
4052 /* if slice left is less than think time, wait busy */
4053 if (cic && sample_valid(cic->ttime.ttime_samples)
4054 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
4058 * If think times is less than a jiffy than ttime_mean=0 and above
4059 * will not be true. It might happen that slice has not expired yet
4060 * but will expire soon (4-5 ns) during select_queue(). To cover the
4061 * case where think time is less than a jiffy, mark the queue wait
4062 * busy if only 1 jiffy is left in the slice.
4064 if (cfqq->slice_end - jiffies == 1)
4070 static void cfq_completed_request(struct request_queue *q, struct request *rq)
4072 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4073 struct cfq_data *cfqd = cfqq->cfqd;
4074 const int sync = rq_is_sync(rq);
4078 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4079 !!(rq->cmd_flags & REQ_NOIDLE));
4081 cfq_update_hw_tag(cfqd);
4083 WARN_ON(!cfqd->rq_in_driver);
4084 WARN_ON(!cfqq->dispatched);
4085 cfqd->rq_in_driver--;
4087 (RQ_CFQG(rq))->dispatched--;
4088 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4089 rq_io_start_time_ns(rq), rq->cmd_flags);
4091 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4094 struct cfq_rb_root *st;
4096 RQ_CIC(rq)->ttime.last_end_request = now;
4098 if (cfq_cfqq_on_rr(cfqq))
4099 st = cfqq->service_tree;
4101 st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4104 st->ttime.last_end_request = now;
4105 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
4106 cfqd->last_delayed_sync = now;
4109 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4110 cfqq->cfqg->ttime.last_end_request = now;
4114 * If this is the active queue, check if it needs to be expired,
4115 * or if we want to idle in case it has no pending requests.
4117 if (cfqd->active_queue == cfqq) {
4118 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4120 if (cfq_cfqq_slice_new(cfqq)) {
4121 cfq_set_prio_slice(cfqd, cfqq);
4122 cfq_clear_cfqq_slice_new(cfqq);
4126 * Should we wait for next request to come in before we expire
4129 if (cfq_should_wait_busy(cfqd, cfqq)) {
4130 unsigned long extend_sl = cfqd->cfq_slice_idle;
4131 if (!cfqd->cfq_slice_idle)
4132 extend_sl = cfqd->cfq_group_idle;
4133 cfqq->slice_end = jiffies + extend_sl;
4134 cfq_mark_cfqq_wait_busy(cfqq);
4135 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4139 * Idling is not enabled on:
4141 * - idle-priority queues
4143 * - queues with still some requests queued
4144 * - when there is a close cooperator
4146 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4147 cfq_slice_expired(cfqd, 1);
4148 else if (sync && cfqq_empty &&
4149 !cfq_close_cooperator(cfqd, cfqq)) {
4150 cfq_arm_slice_timer(cfqd);
4154 if (!cfqd->rq_in_driver)
4155 cfq_schedule_dispatch(cfqd);
4158 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4160 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4161 cfq_mark_cfqq_must_alloc_slice(cfqq);
4162 return ELV_MQUEUE_MUST;
4165 return ELV_MQUEUE_MAY;
4168 static int cfq_may_queue(struct request_queue *q, int rw)
4170 struct cfq_data *cfqd = q->elevator->elevator_data;
4171 struct task_struct *tsk = current;
4172 struct cfq_io_cq *cic;
4173 struct cfq_queue *cfqq;
4176 * don't force setup of a queue from here, as a call to may_queue
4177 * does not necessarily imply that a request actually will be queued.
4178 * so just lookup a possibly existing queue, or return 'may queue'
4181 cic = cfq_cic_lookup(cfqd, tsk->io_context);
4183 return ELV_MQUEUE_MAY;
4185 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
4187 cfq_init_prio_data(cfqq, cic);
4189 return __cfq_may_queue(cfqq);
4192 return ELV_MQUEUE_MAY;
4196 * queue lock held here
4198 static void cfq_put_request(struct request *rq)
4200 struct cfq_queue *cfqq = RQ_CFQQ(rq);
4203 const int rw = rq_data_dir(rq);
4205 BUG_ON(!cfqq->allocated[rw]);
4206 cfqq->allocated[rw]--;
4208 /* Put down rq reference on cfqg */
4209 cfqg_put(RQ_CFQG(rq));
4210 rq->elv.priv[0] = NULL;
4211 rq->elv.priv[1] = NULL;
4213 cfq_put_queue(cfqq);
4217 static struct cfq_queue *
4218 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4219 struct cfq_queue *cfqq)
4221 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4222 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4223 cfq_mark_cfqq_coop(cfqq->new_cfqq);
4224 cfq_put_queue(cfqq);
4225 return cic_to_cfqq(cic, 1);
4229 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4230 * was the last process referring to said cfqq.
4232 static struct cfq_queue *
4233 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4235 if (cfqq_process_refs(cfqq) == 1) {
4236 cfqq->pid = current->pid;
4237 cfq_clear_cfqq_coop(cfqq);
4238 cfq_clear_cfqq_split_coop(cfqq);
4242 cic_set_cfqq(cic, NULL, 1);
4244 cfq_put_cooperator(cfqq);
4246 cfq_put_queue(cfqq);
4250 * Allocate cfq data structures associated with this request.
4253 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4256 struct cfq_data *cfqd = q->elevator->elevator_data;
4257 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4258 const int rw = rq_data_dir(rq);
4259 const bool is_sync = rq_is_sync(rq);
4260 struct cfq_queue *cfqq;
4262 spin_lock_irq(q->queue_lock);
4264 check_ioprio_changed(cic, bio);
4265 check_blkcg_changed(cic, bio);
4267 cfqq = cic_to_cfqq(cic, is_sync);
4268 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4270 cfq_put_queue(cfqq);
4271 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4272 cic_set_cfqq(cic, cfqq, is_sync);
4275 * If the queue was seeky for too long, break it apart.
4277 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4278 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4279 cfqq = split_cfqq(cic, cfqq);
4285 * Check to see if this queue is scheduled to merge with
4286 * another, closely cooperating queue. The merging of
4287 * queues happens here as it must be done in process context.
4288 * The reference on new_cfqq was taken in merge_cfqqs.
4291 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4294 cfqq->allocated[rw]++;
4297 cfqg_get(cfqq->cfqg);
4298 rq->elv.priv[0] = cfqq;
4299 rq->elv.priv[1] = cfqq->cfqg;
4300 spin_unlock_irq(q->queue_lock);
4304 static void cfq_kick_queue(struct work_struct *work)
4306 struct cfq_data *cfqd =
4307 container_of(work, struct cfq_data, unplug_work);
4308 struct request_queue *q = cfqd->queue;
4310 spin_lock_irq(q->queue_lock);
4311 __blk_run_queue(cfqd->queue);
4312 spin_unlock_irq(q->queue_lock);
4316 * Timer running if the active_queue is currently idling inside its time slice
4318 static void cfq_idle_slice_timer(unsigned long data)
4320 struct cfq_data *cfqd = (struct cfq_data *) data;
4321 struct cfq_queue *cfqq;
4322 unsigned long flags;
4325 cfq_log(cfqd, "idle timer fired");
4327 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4329 cfqq = cfqd->active_queue;
4334 * We saw a request before the queue expired, let it through
4336 if (cfq_cfqq_must_dispatch(cfqq))
4342 if (cfq_slice_used(cfqq))
4346 * only expire and reinvoke request handler, if there are
4347 * other queues with pending requests
4349 if (!cfqd->busy_queues)
4353 * not expired and it has a request pending, let it dispatch
4355 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4359 * Queue depth flag is reset only when the idle didn't succeed
4361 cfq_clear_cfqq_deep(cfqq);
4364 cfq_slice_expired(cfqd, timed_out);
4366 cfq_schedule_dispatch(cfqd);
4368 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4371 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4373 del_timer_sync(&cfqd->idle_slice_timer);
4374 cancel_work_sync(&cfqd->unplug_work);
4377 static void cfq_put_async_queues(struct cfq_data *cfqd)
4381 for (i = 0; i < IOPRIO_BE_NR; i++) {
4382 if (cfqd->async_cfqq[0][i])
4383 cfq_put_queue(cfqd->async_cfqq[0][i]);
4384 if (cfqd->async_cfqq[1][i])
4385 cfq_put_queue(cfqd->async_cfqq[1][i]);
4388 if (cfqd->async_idle_cfqq)
4389 cfq_put_queue(cfqd->async_idle_cfqq);
4392 static void cfq_exit_queue(struct elevator_queue *e)
4394 struct cfq_data *cfqd = e->elevator_data;
4395 struct request_queue *q = cfqd->queue;
4397 cfq_shutdown_timer_wq(cfqd);
4399 spin_lock_irq(q->queue_lock);
4401 if (cfqd->active_queue)
4402 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4404 cfq_put_async_queues(cfqd);
4406 spin_unlock_irq(q->queue_lock);
4408 cfq_shutdown_timer_wq(cfqd);
4410 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4411 blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4413 kfree(cfqd->root_group);
4418 static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4420 struct cfq_data *cfqd;
4421 struct blkcg_gq *blkg __maybe_unused;
4423 struct elevator_queue *eq;
4425 eq = elevator_alloc(q, e);
4429 cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4431 kobject_put(&eq->kobj);
4434 eq->elevator_data = cfqd;
4437 spin_lock_irq(q->queue_lock);
4439 spin_unlock_irq(q->queue_lock);
4441 /* Init root service tree */
4442 cfqd->grp_service_tree = CFQ_RB_ROOT;
4444 /* Init root group and prefer root group over other groups by default */
4445 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4446 ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4450 cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4453 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4454 GFP_KERNEL, cfqd->queue->node);
4455 if (!cfqd->root_group)
4458 cfq_init_cfqg_base(cfqd->root_group);
4460 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
4461 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
4464 * Not strictly needed (since RB_ROOT just clears the node and we
4465 * zeroed cfqd on alloc), but better be safe in case someone decides
4466 * to add magic to the rb code
4468 for (i = 0; i < CFQ_PRIO_LISTS; i++)
4469 cfqd->prio_trees[i] = RB_ROOT;
4472 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4473 * Grab a permanent reference to it, so that the normal code flow
4474 * will not attempt to free it. oom_cfqq is linked to root_group
4475 * but shouldn't hold a reference as it'll never be unlinked. Lose
4476 * the reference from linking right away.
4478 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4479 cfqd->oom_cfqq.ref++;
4481 spin_lock_irq(q->queue_lock);
4482 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4483 cfqg_put(cfqd->root_group);
4484 spin_unlock_irq(q->queue_lock);
4486 init_timer(&cfqd->idle_slice_timer);
4487 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4488 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4490 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4492 cfqd->cfq_quantum = cfq_quantum;
4493 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4494 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4495 cfqd->cfq_back_max = cfq_back_max;
4496 cfqd->cfq_back_penalty = cfq_back_penalty;
4497 cfqd->cfq_slice[0] = cfq_slice_async;
4498 cfqd->cfq_slice[1] = cfq_slice_sync;
4499 cfqd->cfq_target_latency = cfq_target_latency;
4500 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4501 cfqd->cfq_slice_idle = cfq_slice_idle;
4502 cfqd->cfq_group_idle = cfq_group_idle;
4503 cfqd->cfq_latency = 1;
4506 * we optimistically start assuming sync ops weren't delayed in last
4507 * second, in order to have larger depth for async operations.
4509 cfqd->last_delayed_sync = jiffies - HZ;
4514 kobject_put(&eq->kobj);
4518 static void cfq_registered_queue(struct request_queue *q)
4520 struct elevator_queue *e = q->elevator;
4521 struct cfq_data *cfqd = e->elevator_data;
4524 * Default to IOPS mode with no idling for SSDs
4526 if (blk_queue_nonrot(q))
4527 cfqd->cfq_slice_idle = 0;
4531 * sysfs parts below -->
4534 cfq_var_show(unsigned int var, char *page)
4536 return sprintf(page, "%u\n", var);
4540 cfq_var_store(unsigned int *var, const char *page, size_t count)
4542 char *p = (char *) page;
4544 *var = simple_strtoul(p, &p, 10);
4548 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4549 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4551 struct cfq_data *cfqd = e->elevator_data; \
4552 unsigned int __data = __VAR; \
4554 __data = jiffies_to_msecs(__data); \
4555 return cfq_var_show(__data, (page)); \
4557 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4558 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4559 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4560 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4561 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4562 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4563 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4564 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4565 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4566 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4567 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4568 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4569 #undef SHOW_FUNCTION
4571 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4572 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4574 struct cfq_data *cfqd = e->elevator_data; \
4575 unsigned int __data; \
4576 int ret = cfq_var_store(&__data, (page), count); \
4577 if (__data < (MIN)) \
4579 else if (__data > (MAX)) \
4582 *(__PTR) = msecs_to_jiffies(__data); \
4584 *(__PTR) = __data; \
4587 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4588 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4590 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4592 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4593 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4595 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4596 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4597 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4598 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4599 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4601 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4602 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4603 #undef STORE_FUNCTION
4605 #define CFQ_ATTR(name) \
4606 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4608 static struct elv_fs_entry cfq_attrs[] = {
4610 CFQ_ATTR(fifo_expire_sync),
4611 CFQ_ATTR(fifo_expire_async),
4612 CFQ_ATTR(back_seek_max),
4613 CFQ_ATTR(back_seek_penalty),
4614 CFQ_ATTR(slice_sync),
4615 CFQ_ATTR(slice_async),
4616 CFQ_ATTR(slice_async_rq),
4617 CFQ_ATTR(slice_idle),
4618 CFQ_ATTR(group_idle),
4619 CFQ_ATTR(low_latency),
4620 CFQ_ATTR(target_latency),
4624 static struct elevator_type iosched_cfq = {
4626 .elevator_merge_fn = cfq_merge,
4627 .elevator_merged_fn = cfq_merged_request,
4628 .elevator_merge_req_fn = cfq_merged_requests,
4629 .elevator_allow_merge_fn = cfq_allow_merge,
4630 .elevator_bio_merged_fn = cfq_bio_merged,
4631 .elevator_dispatch_fn = cfq_dispatch_requests,
4632 .elevator_add_req_fn = cfq_insert_request,
4633 .elevator_activate_req_fn = cfq_activate_request,
4634 .elevator_deactivate_req_fn = cfq_deactivate_request,
4635 .elevator_completed_req_fn = cfq_completed_request,
4636 .elevator_former_req_fn = elv_rb_former_request,
4637 .elevator_latter_req_fn = elv_rb_latter_request,
4638 .elevator_init_icq_fn = cfq_init_icq,
4639 .elevator_exit_icq_fn = cfq_exit_icq,
4640 .elevator_set_req_fn = cfq_set_request,
4641 .elevator_put_req_fn = cfq_put_request,
4642 .elevator_may_queue_fn = cfq_may_queue,
4643 .elevator_init_fn = cfq_init_queue,
4644 .elevator_exit_fn = cfq_exit_queue,
4645 .elevator_registered_fn = cfq_registered_queue,
4647 .icq_size = sizeof(struct cfq_io_cq),
4648 .icq_align = __alignof__(struct cfq_io_cq),
4649 .elevator_attrs = cfq_attrs,
4650 .elevator_name = "cfq",
4651 .elevator_owner = THIS_MODULE,
4654 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4655 static struct blkcg_policy blkcg_policy_cfq = {
4656 .pd_size = sizeof(struct cfq_group),
4657 .cpd_size = sizeof(struct cfq_group_data),
4658 .cftypes = cfq_blkcg_files,
4660 .cpd_init_fn = cfq_cpd_init,
4661 .pd_init_fn = cfq_pd_init,
4662 .pd_offline_fn = cfq_pd_offline,
4663 .pd_reset_stats_fn = cfq_pd_reset_stats,
4667 static int __init cfq_init(void)
4672 * could be 0 on HZ < 1000 setups
4674 if (!cfq_slice_async)
4675 cfq_slice_async = 1;
4676 if (!cfq_slice_idle)
4679 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4680 if (!cfq_group_idle)
4683 ret = blkcg_policy_register(&blkcg_policy_cfq);
4691 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4695 ret = elv_register(&iosched_cfq);
4702 kmem_cache_destroy(cfq_pool);
4704 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4705 blkcg_policy_unregister(&blkcg_policy_cfq);
4710 static void __exit cfq_exit(void)
4712 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4713 blkcg_policy_unregister(&blkcg_policy_cfq);
4715 elv_unregister(&iosched_cfq);
4716 kmem_cache_destroy(cfq_pool);
4719 module_init(cfq_init);
4720 module_exit(cfq_exit);
4722 MODULE_AUTHOR("Jens Axboe");
4723 MODULE_LICENSE("GPL");
4724 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");