2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
18 #include "blk-cgroup.h"
23 /* max queue in one round of service */
24 static const int cfq_quantum
= 8;
25 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max
= 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty
= 2;
30 static const int cfq_slice_sync
= HZ
/ 10;
31 static int cfq_slice_async
= HZ
/ 25;
32 static const int cfq_slice_async_rq
= 2;
33 static int cfq_slice_idle
= HZ
/ 125;
34 static int cfq_group_idle
= HZ
/ 125;
35 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
36 static const int cfq_hist_divisor
= 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache
*cfq_pool
;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
71 unsigned long last_end_request
;
73 unsigned long ttime_total
;
74 unsigned long ttime_samples
;
75 unsigned long ttime_mean
;
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
89 struct cfq_ttime ttime
;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
92 .ttime = {.last_end_request = jiffies,},}
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data
*cfqd
;
104 /* service_tree member */
105 struct rb_node rb_node
;
106 /* service_tree key */
107 unsigned long rb_key
;
108 /* prio tree member */
109 struct rb_node p_node
;
110 /* prio tree root we belong to, if any */
111 struct rb_root
*p_root
;
112 /* sorted list of pending requests */
113 struct rb_root sort_list
;
114 /* if fifo isn't expired, next request to serve */
115 struct request
*next_rq
;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo
;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start
;
125 unsigned int allocated_slice
;
126 unsigned int slice_dispatch
;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start
;
129 unsigned long slice_end
;
132 /* pending priority requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio
, org_ioprio
;
139 unsigned short ioprio_class
;
144 sector_t last_request_pos
;
146 struct cfq_rb_root
*service_tree
;
147 struct cfq_queue
*new_cfqq
;
148 struct cfq_group
*cfqg
;
149 /* Number of sectors dispatched from queue in single dispatch round */
150 unsigned long nr_sectors
;
154 * First index in the service_trees.
155 * IDLE is handled separately, so it has negative index
165 * Second index in the service_trees.
169 SYNC_NOIDLE_WORKLOAD
= 1,
174 #ifdef CONFIG_CFQ_GROUP_IOSCHED
175 /* total bytes transferred */
176 struct blkg_rwstat service_bytes
;
177 /* total IOs serviced, post merge */
178 struct blkg_rwstat serviced
;
179 /* number of ios merged */
180 struct blkg_rwstat merged
;
181 /* total time spent on device in ns, may not be accurate w/ queueing */
182 struct blkg_rwstat service_time
;
183 /* total time spent waiting in scheduler queue in ns */
184 struct blkg_rwstat wait_time
;
185 /* number of IOs queued up */
186 struct blkg_rwstat queued
;
187 /* total sectors transferred */
188 struct blkg_stat sectors
;
189 /* total disk time and nr sectors dispatched by this group */
190 struct blkg_stat time
;
191 #ifdef CONFIG_DEBUG_BLK_CGROUP
192 /* time not charged to this cgroup */
193 struct blkg_stat unaccounted_time
;
194 /* sum of number of ios queued across all samples */
195 struct blkg_stat avg_queue_size_sum
;
196 /* count of samples taken for average */
197 struct blkg_stat avg_queue_size_samples
;
198 /* how many times this group has been removed from service tree */
199 struct blkg_stat dequeue
;
200 /* total time spent waiting for it to be assigned a timeslice. */
201 struct blkg_stat group_wait_time
;
202 /* time spent idling for this blkcg_gq */
203 struct blkg_stat idle_time
;
204 /* total time with empty current active q with other requests queued */
205 struct blkg_stat empty_time
;
206 /* fields after this shouldn't be cleared on stat reset */
207 uint64_t start_group_wait_time
;
208 uint64_t start_idle_time
;
209 uint64_t start_empty_time
;
211 #endif /* CONFIG_DEBUG_BLK_CGROUP */
212 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
215 /* This is per cgroup per device grouping structure */
217 /* must be the first member */
218 struct blkg_policy_data pd
;
220 /* group service_tree member */
221 struct rb_node rb_node
;
223 /* group service_tree key */
227 * The number of active cfqgs and sum of their weights under this
228 * cfqg. This covers this cfqg's leaf_weight and all children's
229 * weights, but does not cover weights of further descendants.
231 * If a cfqg is on the service tree, it's active. An active cfqg
232 * also activates its parent and contributes to the children_weight
236 unsigned int children_weight
;
239 * vfraction is the fraction of vdisktime that the tasks in this
240 * cfqg are entitled to. This is determined by compounding the
241 * ratios walking up from this cfqg to the root.
243 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
244 * vfractions on a service tree is approximately 1. The sum may
245 * deviate a bit due to rounding errors and fluctuations caused by
246 * cfqgs entering and leaving the service tree.
248 unsigned int vfraction
;
251 * There are two weights - (internal) weight is the weight of this
252 * cfqg against the sibling cfqgs. leaf_weight is the wight of
253 * this cfqg against the child cfqgs. For the root cfqg, both
254 * weights are kept in sync for backward compatibility.
257 unsigned int new_weight
;
258 unsigned int dev_weight
;
260 unsigned int leaf_weight
;
261 unsigned int new_leaf_weight
;
262 unsigned int dev_leaf_weight
;
264 /* number of cfqq currently on this group */
268 * Per group busy queues average. Useful for workload slice calc. We
269 * create the array for each prio class but at run time it is used
270 * only for RT and BE class and slot for IDLE class remains unused.
271 * This is primarily done to avoid confusion and a gcc warning.
273 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
275 * rr lists of queues with requests. We maintain service trees for
276 * RT and BE classes. These trees are subdivided in subclasses
277 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
278 * class there is no subclassification and all the cfq queues go on
279 * a single tree service_tree_idle.
280 * Counts are embedded in the cfq_rb_root
282 struct cfq_rb_root service_trees
[2][3];
283 struct cfq_rb_root service_tree_idle
;
285 unsigned long saved_wl_slice
;
286 enum wl_type_t saved_wl_type
;
287 enum wl_class_t saved_wl_class
;
289 /* number of requests that are on the dispatch list or inside driver */
291 struct cfq_ttime ttime
;
292 struct cfqg_stats stats
; /* stats for this cfqg */
293 struct cfqg_stats dead_stats
; /* stats pushed from dead children */
297 struct io_cq icq
; /* must be the first member */
298 struct cfq_queue
*cfqq
[2];
299 struct cfq_ttime ttime
;
300 int ioprio
; /* the current ioprio */
301 #ifdef CONFIG_CFQ_GROUP_IOSCHED
302 uint64_t blkcg_id
; /* the current blkcg ID */
307 * Per block device queue structure
310 struct request_queue
*queue
;
311 /* Root service tree for cfq_groups */
312 struct cfq_rb_root grp_service_tree
;
313 struct cfq_group
*root_group
;
316 * The priority currently being served
318 enum wl_class_t serving_wl_class
;
319 enum wl_type_t serving_wl_type
;
320 unsigned long workload_expires
;
321 struct cfq_group
*serving_group
;
324 * Each priority tree is sorted by next_request position. These
325 * trees are used when determining if two or more queues are
326 * interleaving requests (see cfq_close_cooperator).
328 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
330 unsigned int busy_queues
;
331 unsigned int busy_sync_queues
;
337 * queue-depth detection
343 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
344 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
347 int hw_tag_est_depth
;
348 unsigned int hw_tag_samples
;
351 * idle window management
353 struct timer_list idle_slice_timer
;
354 struct work_struct unplug_work
;
356 struct cfq_queue
*active_queue
;
357 struct cfq_io_cq
*active_cic
;
360 * async queue for each priority case
362 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
363 struct cfq_queue
*async_idle_cfqq
;
365 sector_t last_position
;
368 * tunables, see top of file
370 unsigned int cfq_quantum
;
371 unsigned int cfq_fifo_expire
[2];
372 unsigned int cfq_back_penalty
;
373 unsigned int cfq_back_max
;
374 unsigned int cfq_slice
[2];
375 unsigned int cfq_slice_async_rq
;
376 unsigned int cfq_slice_idle
;
377 unsigned int cfq_group_idle
;
378 unsigned int cfq_latency
;
379 unsigned int cfq_target_latency
;
382 * Fallback dummy cfqq for extreme OOM conditions
384 struct cfq_queue oom_cfqq
;
386 unsigned long last_delayed_sync
;
389 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
391 static struct cfq_rb_root
*st_for(struct cfq_group
*cfqg
,
392 enum wl_class_t
class,
398 if (class == IDLE_WORKLOAD
)
399 return &cfqg
->service_tree_idle
;
401 return &cfqg
->service_trees
[class][type
];
404 enum cfqq_state_flags
{
405 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
406 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
407 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
408 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
409 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
410 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
411 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
412 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
413 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
414 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
415 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
416 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
417 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
420 #define CFQ_CFQQ_FNS(name) \
421 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
423 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
425 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
427 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
429 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
431 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
435 CFQ_CFQQ_FNS(wait_request
);
436 CFQ_CFQQ_FNS(must_dispatch
);
437 CFQ_CFQQ_FNS(must_alloc_slice
);
438 CFQ_CFQQ_FNS(fifo_expire
);
439 CFQ_CFQQ_FNS(idle_window
);
440 CFQ_CFQQ_FNS(prio_changed
);
441 CFQ_CFQQ_FNS(slice_new
);
444 CFQ_CFQQ_FNS(split_coop
);
446 CFQ_CFQQ_FNS(wait_busy
);
449 static inline struct cfq_group
*pd_to_cfqg(struct blkg_policy_data
*pd
)
451 return pd
? container_of(pd
, struct cfq_group
, pd
) : NULL
;
454 static inline struct blkcg_gq
*cfqg_to_blkg(struct cfq_group
*cfqg
)
456 return pd_to_blkg(&cfqg
->pd
);
459 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
461 /* cfqg stats flags */
462 enum cfqg_stats_flags
{
463 CFQG_stats_waiting
= 0,
468 #define CFQG_FLAG_FNS(name) \
469 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
471 stats->flags |= (1 << CFQG_stats_##name); \
473 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
475 stats->flags &= ~(1 << CFQG_stats_##name); \
477 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
479 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
482 CFQG_FLAG_FNS(waiting)
483 CFQG_FLAG_FNS(idling
)
487 /* This should be called with the queue_lock held. */
488 static void cfqg_stats_update_group_wait_time(struct cfqg_stats
*stats
)
490 unsigned long long now
;
492 if (!cfqg_stats_waiting(stats
))
496 if (time_after64(now
, stats
->start_group_wait_time
))
497 blkg_stat_add(&stats
->group_wait_time
,
498 now
- stats
->start_group_wait_time
);
499 cfqg_stats_clear_waiting(stats
);
502 /* This should be called with the queue_lock held. */
503 static void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
,
504 struct cfq_group
*curr_cfqg
)
506 struct cfqg_stats
*stats
= &cfqg
->stats
;
508 if (cfqg_stats_waiting(stats
))
510 if (cfqg
== curr_cfqg
)
512 stats
->start_group_wait_time
= sched_clock();
513 cfqg_stats_mark_waiting(stats
);
516 /* This should be called with the queue_lock held. */
517 static void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
)
519 unsigned long long now
;
521 if (!cfqg_stats_empty(stats
))
525 if (time_after64(now
, stats
->start_empty_time
))
526 blkg_stat_add(&stats
->empty_time
,
527 now
- stats
->start_empty_time
);
528 cfqg_stats_clear_empty(stats
);
531 static void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
)
533 blkg_stat_add(&cfqg
->stats
.dequeue
, 1);
536 static void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
)
538 struct cfqg_stats
*stats
= &cfqg
->stats
;
540 if (blkg_rwstat_total(&stats
->queued
))
544 * group is already marked empty. This can happen if cfqq got new
545 * request in parent group and moved to this group while being added
546 * to service tree. Just ignore the event and move on.
548 if (cfqg_stats_empty(stats
))
551 stats
->start_empty_time
= sched_clock();
552 cfqg_stats_mark_empty(stats
);
555 static void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
)
557 struct cfqg_stats
*stats
= &cfqg
->stats
;
559 if (cfqg_stats_idling(stats
)) {
560 unsigned long long now
= sched_clock();
562 if (time_after64(now
, stats
->start_idle_time
))
563 blkg_stat_add(&stats
->idle_time
,
564 now
- stats
->start_idle_time
);
565 cfqg_stats_clear_idling(stats
);
569 static void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
)
571 struct cfqg_stats
*stats
= &cfqg
->stats
;
573 BUG_ON(cfqg_stats_idling(stats
));
575 stats
->start_idle_time
= sched_clock();
576 cfqg_stats_mark_idling(stats
);
579 static void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
)
581 struct cfqg_stats
*stats
= &cfqg
->stats
;
583 blkg_stat_add(&stats
->avg_queue_size_sum
,
584 blkg_rwstat_total(&stats
->queued
));
585 blkg_stat_add(&stats
->avg_queue_size_samples
, 1);
586 cfqg_stats_update_group_wait_time(stats
);
589 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
591 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
, struct cfq_group
*curr_cfqg
) { }
592 static inline void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
) { }
593 static inline void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
) { }
594 static inline void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
) { }
595 static inline void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
) { }
596 static inline void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
) { }
597 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
) { }
599 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
601 #ifdef CONFIG_CFQ_GROUP_IOSCHED
603 static struct blkcg_policy blkcg_policy_cfq
;
605 static inline struct cfq_group
*blkg_to_cfqg(struct blkcg_gq
*blkg
)
607 return pd_to_cfqg(blkg_to_pd(blkg
, &blkcg_policy_cfq
));
610 static inline struct cfq_group
*cfqg_parent(struct cfq_group
*cfqg
)
612 struct blkcg_gq
*pblkg
= cfqg_to_blkg(cfqg
)->parent
;
614 return pblkg
? blkg_to_cfqg(pblkg
) : NULL
;
617 static inline void cfqg_get(struct cfq_group
*cfqg
)
619 return blkg_get(cfqg_to_blkg(cfqg
));
622 static inline void cfqg_put(struct cfq_group
*cfqg
)
624 return blkg_put(cfqg_to_blkg(cfqg
));
627 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
630 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
631 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
632 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
633 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
637 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
640 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
641 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
644 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
645 struct cfq_group
*curr_cfqg
, int rw
)
647 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, 1);
648 cfqg_stats_end_empty_time(&cfqg
->stats
);
649 cfqg_stats_set_start_group_wait_time(cfqg
, curr_cfqg
);
652 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
653 unsigned long time
, unsigned long unaccounted_time
)
655 blkg_stat_add(&cfqg
->stats
.time
, time
);
656 #ifdef CONFIG_DEBUG_BLK_CGROUP
657 blkg_stat_add(&cfqg
->stats
.unaccounted_time
, unaccounted_time
);
661 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
)
663 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, -1);
666 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
)
668 blkg_rwstat_add(&cfqg
->stats
.merged
, rw
, 1);
671 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
672 uint64_t bytes
, int rw
)
674 blkg_stat_add(&cfqg
->stats
.sectors
, bytes
>> 9);
675 blkg_rwstat_add(&cfqg
->stats
.serviced
, rw
, 1);
676 blkg_rwstat_add(&cfqg
->stats
.service_bytes
, rw
, bytes
);
679 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
680 uint64_t start_time
, uint64_t io_start_time
, int rw
)
682 struct cfqg_stats
*stats
= &cfqg
->stats
;
683 unsigned long long now
= sched_clock();
685 if (time_after64(now
, io_start_time
))
686 blkg_rwstat_add(&stats
->service_time
, rw
, now
- io_start_time
);
687 if (time_after64(io_start_time
, start_time
))
688 blkg_rwstat_add(&stats
->wait_time
, rw
,
689 io_start_time
- start_time
);
693 static void cfqg_stats_reset(struct cfqg_stats
*stats
)
695 /* queued stats shouldn't be cleared */
696 blkg_rwstat_reset(&stats
->service_bytes
);
697 blkg_rwstat_reset(&stats
->serviced
);
698 blkg_rwstat_reset(&stats
->merged
);
699 blkg_rwstat_reset(&stats
->service_time
);
700 blkg_rwstat_reset(&stats
->wait_time
);
701 blkg_stat_reset(&stats
->time
);
702 #ifdef CONFIG_DEBUG_BLK_CGROUP
703 blkg_stat_reset(&stats
->unaccounted_time
);
704 blkg_stat_reset(&stats
->avg_queue_size_sum
);
705 blkg_stat_reset(&stats
->avg_queue_size_samples
);
706 blkg_stat_reset(&stats
->dequeue
);
707 blkg_stat_reset(&stats
->group_wait_time
);
708 blkg_stat_reset(&stats
->idle_time
);
709 blkg_stat_reset(&stats
->empty_time
);
714 static void cfqg_stats_merge(struct cfqg_stats
*to
, struct cfqg_stats
*from
)
716 /* queued stats shouldn't be cleared */
717 blkg_rwstat_merge(&to
->service_bytes
, &from
->service_bytes
);
718 blkg_rwstat_merge(&to
->serviced
, &from
->serviced
);
719 blkg_rwstat_merge(&to
->merged
, &from
->merged
);
720 blkg_rwstat_merge(&to
->service_time
, &from
->service_time
);
721 blkg_rwstat_merge(&to
->wait_time
, &from
->wait_time
);
722 blkg_stat_merge(&from
->time
, &from
->time
);
723 #ifdef CONFIG_DEBUG_BLK_CGROUP
724 blkg_stat_merge(&to
->unaccounted_time
, &from
->unaccounted_time
);
725 blkg_stat_merge(&to
->avg_queue_size_sum
, &from
->avg_queue_size_sum
);
726 blkg_stat_merge(&to
->avg_queue_size_samples
, &from
->avg_queue_size_samples
);
727 blkg_stat_merge(&to
->dequeue
, &from
->dequeue
);
728 blkg_stat_merge(&to
->group_wait_time
, &from
->group_wait_time
);
729 blkg_stat_merge(&to
->idle_time
, &from
->idle_time
);
730 blkg_stat_merge(&to
->empty_time
, &from
->empty_time
);
735 * Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
736 * recursive stats can still account for the amount used by this cfqg after
739 static void cfqg_stats_xfer_dead(struct cfq_group
*cfqg
)
741 struct cfq_group
*parent
= cfqg_parent(cfqg
);
743 lockdep_assert_held(cfqg_to_blkg(cfqg
)->q
->queue_lock
);
745 if (unlikely(!parent
))
748 cfqg_stats_merge(&parent
->dead_stats
, &cfqg
->stats
);
749 cfqg_stats_merge(&parent
->dead_stats
, &cfqg
->dead_stats
);
750 cfqg_stats_reset(&cfqg
->stats
);
751 cfqg_stats_reset(&cfqg
->dead_stats
);
754 #else /* CONFIG_CFQ_GROUP_IOSCHED */
756 static inline struct cfq_group
*cfqg_parent(struct cfq_group
*cfqg
) { return NULL
; }
757 static inline void cfqg_get(struct cfq_group
*cfqg
) { }
758 static inline void cfqg_put(struct cfq_group
*cfqg
) { }
760 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
761 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
762 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
763 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
765 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
767 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
768 struct cfq_group
*curr_cfqg
, int rw
) { }
769 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
770 unsigned long time
, unsigned long unaccounted_time
) { }
771 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
) { }
772 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
) { }
773 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
774 uint64_t bytes
, int rw
) { }
775 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
776 uint64_t start_time
, uint64_t io_start_time
, int rw
) { }
778 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
780 #define cfq_log(cfqd, fmt, args...) \
781 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
783 /* Traverses through cfq group service trees */
784 #define for_each_cfqg_st(cfqg, i, j, st) \
785 for (i = 0; i <= IDLE_WORKLOAD; i++) \
786 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
787 : &cfqg->service_tree_idle; \
788 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
789 (i == IDLE_WORKLOAD && j == 0); \
790 j++, st = i < IDLE_WORKLOAD ? \
791 &cfqg->service_trees[i][j]: NULL) \
793 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
794 struct cfq_ttime
*ttime
, bool group_idle
)
797 if (!sample_valid(ttime
->ttime_samples
))
800 slice
= cfqd
->cfq_group_idle
;
802 slice
= cfqd
->cfq_slice_idle
;
803 return ttime
->ttime_mean
> slice
;
806 static inline bool iops_mode(struct cfq_data
*cfqd
)
809 * If we are not idling on queues and it is a NCQ drive, parallel
810 * execution of requests is on and measuring time is not possible
811 * in most of the cases until and unless we drive shallower queue
812 * depths and that becomes a performance bottleneck. In such cases
813 * switch to start providing fairness in terms of number of IOs.
815 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
821 static inline enum wl_class_t
cfqq_class(struct cfq_queue
*cfqq
)
823 if (cfq_class_idle(cfqq
))
824 return IDLE_WORKLOAD
;
825 if (cfq_class_rt(cfqq
))
831 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
833 if (!cfq_cfqq_sync(cfqq
))
834 return ASYNC_WORKLOAD
;
835 if (!cfq_cfqq_idle_window(cfqq
))
836 return SYNC_NOIDLE_WORKLOAD
;
837 return SYNC_WORKLOAD
;
840 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class
,
841 struct cfq_data
*cfqd
,
842 struct cfq_group
*cfqg
)
844 if (wl_class
== IDLE_WORKLOAD
)
845 return cfqg
->service_tree_idle
.count
;
847 return cfqg
->service_trees
[wl_class
][ASYNC_WORKLOAD
].count
+
848 cfqg
->service_trees
[wl_class
][SYNC_NOIDLE_WORKLOAD
].count
+
849 cfqg
->service_trees
[wl_class
][SYNC_WORKLOAD
].count
;
852 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
853 struct cfq_group
*cfqg
)
855 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
+
856 cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
859 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
860 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
,
861 struct cfq_io_cq
*cic
, struct bio
*bio
,
864 static inline struct cfq_io_cq
*icq_to_cic(struct io_cq
*icq
)
866 /* cic->icq is the first member, %NULL will convert to %NULL */
867 return container_of(icq
, struct cfq_io_cq
, icq
);
870 static inline struct cfq_io_cq
*cfq_cic_lookup(struct cfq_data
*cfqd
,
871 struct io_context
*ioc
)
874 return icq_to_cic(ioc_lookup_icq(ioc
, cfqd
->queue
));
878 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_cq
*cic
, bool is_sync
)
880 return cic
->cfqq
[is_sync
];
883 static inline void cic_set_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
,
886 cic
->cfqq
[is_sync
] = cfqq
;
889 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_cq
*cic
)
891 return cic
->icq
.q
->elevator
->elevator_data
;
895 * We regard a request as SYNC, if it's either a read or has the SYNC bit
896 * set (in which case it could also be direct WRITE).
898 static inline bool cfq_bio_sync(struct bio
*bio
)
900 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
904 * scheduler run of queue, if there are requests pending and no one in the
905 * driver that will restart queueing
907 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
909 if (cfqd
->busy_queues
) {
910 cfq_log(cfqd
, "schedule dispatch");
911 kblockd_schedule_work(&cfqd
->unplug_work
);
916 * Scale schedule slice based on io priority. Use the sync time slice only
917 * if a queue is marked sync and has sync io queued. A sync queue with async
918 * io only, should not get full sync slice length.
920 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
923 const int base_slice
= cfqd
->cfq_slice
[sync
];
925 WARN_ON(prio
>= IOPRIO_BE_NR
);
927 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
931 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
933 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
937 * cfqg_scale_charge - scale disk time charge according to cfqg weight
938 * @charge: disk time being charged
939 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
941 * Scale @charge according to @vfraction, which is in range (0, 1]. The
942 * scaling is inversely proportional.
944 * scaled = charge / vfraction
946 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
948 static inline u64
cfqg_scale_charge(unsigned long charge
,
949 unsigned int vfraction
)
951 u64 c
= charge
<< CFQ_SERVICE_SHIFT
; /* make it fixed point */
953 /* charge / vfraction */
954 c
<<= CFQ_SERVICE_SHIFT
;
955 do_div(c
, vfraction
);
959 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
961 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
963 min_vdisktime
= vdisktime
;
965 return min_vdisktime
;
968 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
970 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
972 min_vdisktime
= vdisktime
;
974 return min_vdisktime
;
977 static void update_min_vdisktime(struct cfq_rb_root
*st
)
979 struct cfq_group
*cfqg
;
982 cfqg
= rb_entry_cfqg(st
->left
);
983 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
989 * get averaged number of queues of RT/BE priority.
990 * average is updated, with a formula that gives more weight to higher numbers,
991 * to quickly follows sudden increases and decrease slowly
994 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
995 struct cfq_group
*cfqg
, bool rt
)
997 unsigned min_q
, max_q
;
998 unsigned mult
= cfq_hist_divisor
- 1;
999 unsigned round
= cfq_hist_divisor
/ 2;
1000 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
1002 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
1003 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
1004 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
1006 return cfqg
->busy_queues_avg
[rt
];
1009 static inline unsigned
1010 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1012 return cfqd
->cfq_target_latency
* cfqg
->vfraction
>> CFQ_SERVICE_SHIFT
;
1015 static inline unsigned
1016 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1018 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
1019 if (cfqd
->cfq_latency
) {
1021 * interested queues (we consider only the ones with the same
1022 * priority class in the cfq group)
1024 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
1025 cfq_class_rt(cfqq
));
1026 unsigned sync_slice
= cfqd
->cfq_slice
[1];
1027 unsigned expect_latency
= sync_slice
* iq
;
1028 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
1030 if (expect_latency
> group_slice
) {
1031 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
1032 /* scale low_slice according to IO priority
1033 * and sync vs async */
1034 unsigned low_slice
=
1035 min(slice
, base_low_slice
* slice
/ sync_slice
);
1036 /* the adapted slice value is scaled to fit all iqs
1037 * into the target latency */
1038 slice
= max(slice
* group_slice
/ expect_latency
,
1046 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1048 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1050 cfqq
->slice_start
= jiffies
;
1051 cfqq
->slice_end
= jiffies
+ slice
;
1052 cfqq
->allocated_slice
= slice
;
1053 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
1057 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1058 * isn't valid until the first request from the dispatch is activated
1059 * and the slice time set.
1061 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
1063 if (cfq_cfqq_slice_new(cfqq
))
1065 if (time_before(jiffies
, cfqq
->slice_end
))
1072 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1073 * We choose the request that is closest to the head right now. Distance
1074 * behind the head is penalized and only allowed to a certain extent.
1076 static struct request
*
1077 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
1079 sector_t s1
, s2
, d1
= 0, d2
= 0;
1080 unsigned long back_max
;
1081 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
1082 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
1083 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
1085 if (rq1
== NULL
|| rq1
== rq2
)
1090 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
1091 return rq_is_sync(rq1
) ? rq1
: rq2
;
1093 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
1094 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
1096 s1
= blk_rq_pos(rq1
);
1097 s2
= blk_rq_pos(rq2
);
1100 * by definition, 1KiB is 2 sectors
1102 back_max
= cfqd
->cfq_back_max
* 2;
1105 * Strict one way elevator _except_ in the case where we allow
1106 * short backward seeks which are biased as twice the cost of a
1107 * similar forward seek.
1111 else if (s1
+ back_max
>= last
)
1112 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
1114 wrap
|= CFQ_RQ1_WRAP
;
1118 else if (s2
+ back_max
>= last
)
1119 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
1121 wrap
|= CFQ_RQ2_WRAP
;
1123 /* Found required data */
1126 * By doing switch() on the bit mask "wrap" we avoid having to
1127 * check two variables for all permutations: --> faster!
1130 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1146 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
1149 * Since both rqs are wrapped,
1150 * start with the one that's further behind head
1151 * (--> only *one* back seek required),
1152 * since back seek takes more time than forward.
1162 * The below is leftmost cache rbtree addon
1164 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
1166 /* Service tree is empty */
1171 root
->left
= rb_first(&root
->rb
);
1174 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
1179 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
1182 root
->left
= rb_first(&root
->rb
);
1185 return rb_entry_cfqg(root
->left
);
1190 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
1196 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
1198 if (root
->left
== n
)
1200 rb_erase_init(n
, &root
->rb
);
1205 * would be nice to take fifo expire time into account as well
1207 static struct request
*
1208 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1209 struct request
*last
)
1211 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
1212 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
1213 struct request
*next
= NULL
, *prev
= NULL
;
1215 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
1218 prev
= rb_entry_rq(rbprev
);
1221 next
= rb_entry_rq(rbnext
);
1223 rbnext
= rb_first(&cfqq
->sort_list
);
1224 if (rbnext
&& rbnext
!= &last
->rb_node
)
1225 next
= rb_entry_rq(rbnext
);
1228 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
1231 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
1232 struct cfq_queue
*cfqq
)
1235 * just an approximation, should be ok.
1237 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
1238 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
1242 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1244 return cfqg
->vdisktime
- st
->min_vdisktime
;
1248 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1250 struct rb_node
**node
= &st
->rb
.rb_node
;
1251 struct rb_node
*parent
= NULL
;
1252 struct cfq_group
*__cfqg
;
1253 s64 key
= cfqg_key(st
, cfqg
);
1256 while (*node
!= NULL
) {
1258 __cfqg
= rb_entry_cfqg(parent
);
1260 if (key
< cfqg_key(st
, __cfqg
))
1261 node
= &parent
->rb_left
;
1263 node
= &parent
->rb_right
;
1269 st
->left
= &cfqg
->rb_node
;
1271 rb_link_node(&cfqg
->rb_node
, parent
, node
);
1272 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
1276 cfq_update_group_weight(struct cfq_group
*cfqg
)
1278 if (cfqg
->new_weight
) {
1279 cfqg
->weight
= cfqg
->new_weight
;
1280 cfqg
->new_weight
= 0;
1285 cfq_update_group_leaf_weight(struct cfq_group
*cfqg
)
1287 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1289 if (cfqg
->new_leaf_weight
) {
1290 cfqg
->leaf_weight
= cfqg
->new_leaf_weight
;
1291 cfqg
->new_leaf_weight
= 0;
1296 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1298 unsigned int vfr
= 1 << CFQ_SERVICE_SHIFT
; /* start with 1 */
1299 struct cfq_group
*pos
= cfqg
;
1300 struct cfq_group
*parent
;
1303 /* add to the service tree */
1304 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1306 cfq_update_group_leaf_weight(cfqg
);
1307 __cfq_group_service_tree_add(st
, cfqg
);
1310 * Activate @cfqg and calculate the portion of vfraction @cfqg is
1311 * entitled to. vfraction is calculated by walking the tree
1312 * towards the root calculating the fraction it has at each level.
1313 * The compounded ratio is how much vfraction @cfqg owns.
1315 * Start with the proportion tasks in this cfqg has against active
1316 * children cfqgs - its leaf_weight against children_weight.
1318 propagate
= !pos
->nr_active
++;
1319 pos
->children_weight
+= pos
->leaf_weight
;
1320 vfr
= vfr
* pos
->leaf_weight
/ pos
->children_weight
;
1323 * Compound ->weight walking up the tree. Both activation and
1324 * vfraction calculation are done in the same loop. Propagation
1325 * stops once an already activated node is met. vfraction
1326 * calculation should always continue to the root.
1328 while ((parent
= cfqg_parent(pos
))) {
1330 cfq_update_group_weight(pos
);
1331 propagate
= !parent
->nr_active
++;
1332 parent
->children_weight
+= pos
->weight
;
1334 vfr
= vfr
* pos
->weight
/ parent
->children_weight
;
1338 cfqg
->vfraction
= max_t(unsigned, vfr
, 1);
1342 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1344 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1345 struct cfq_group
*__cfqg
;
1349 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1353 * Currently put the group at the end. Later implement something
1354 * so that groups get lesser vtime based on their weights, so that
1355 * if group does not loose all if it was not continuously backlogged.
1357 n
= rb_last(&st
->rb
);
1359 __cfqg
= rb_entry_cfqg(n
);
1360 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
1362 cfqg
->vdisktime
= st
->min_vdisktime
;
1363 cfq_group_service_tree_add(st
, cfqg
);
1367 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1369 struct cfq_group
*pos
= cfqg
;
1373 * Undo activation from cfq_group_service_tree_add(). Deactivate
1374 * @cfqg and propagate deactivation upwards.
1376 propagate
= !--pos
->nr_active
;
1377 pos
->children_weight
-= pos
->leaf_weight
;
1380 struct cfq_group
*parent
= cfqg_parent(pos
);
1382 /* @pos has 0 nr_active at this point */
1383 WARN_ON_ONCE(pos
->children_weight
);
1389 propagate
= !--parent
->nr_active
;
1390 parent
->children_weight
-= pos
->weight
;
1394 /* remove from the service tree */
1395 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1396 cfq_rb_erase(&cfqg
->rb_node
, st
);
1400 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1402 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1404 BUG_ON(cfqg
->nr_cfqq
< 1);
1407 /* If there are other cfq queues under this group, don't delete it */
1411 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
1412 cfq_group_service_tree_del(st
, cfqg
);
1413 cfqg
->saved_wl_slice
= 0;
1414 cfqg_stats_update_dequeue(cfqg
);
1417 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
1418 unsigned int *unaccounted_time
)
1420 unsigned int slice_used
;
1423 * Queue got expired before even a single request completed or
1424 * got expired immediately after first request completion.
1426 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
1428 * Also charge the seek time incurred to the group, otherwise
1429 * if there are mutiple queues in the group, each can dispatch
1430 * a single request on seeky media and cause lots of seek time
1431 * and group will never know it.
1433 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
1436 slice_used
= jiffies
- cfqq
->slice_start
;
1437 if (slice_used
> cfqq
->allocated_slice
) {
1438 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
1439 slice_used
= cfqq
->allocated_slice
;
1441 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
1442 *unaccounted_time
+= cfqq
->slice_start
-
1443 cfqq
->dispatch_start
;
1449 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
1450 struct cfq_queue
*cfqq
)
1452 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1453 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
1454 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
1455 - cfqg
->service_tree_idle
.count
;
1458 BUG_ON(nr_sync
< 0);
1459 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
1461 if (iops_mode(cfqd
))
1462 charge
= cfqq
->slice_dispatch
;
1463 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
1464 charge
= cfqq
->allocated_slice
;
1467 * Can't update vdisktime while on service tree and cfqg->vfraction
1468 * is valid only while on it. Cache vfr, leave the service tree,
1469 * update vdisktime and go back on. The re-addition to the tree
1470 * will also update the weights as necessary.
1472 vfr
= cfqg
->vfraction
;
1473 cfq_group_service_tree_del(st
, cfqg
);
1474 cfqg
->vdisktime
+= cfqg_scale_charge(charge
, vfr
);
1475 cfq_group_service_tree_add(st
, cfqg
);
1477 /* This group is being expired. Save the context */
1478 if (time_after(cfqd
->workload_expires
, jiffies
)) {
1479 cfqg
->saved_wl_slice
= cfqd
->workload_expires
1481 cfqg
->saved_wl_type
= cfqd
->serving_wl_type
;
1482 cfqg
->saved_wl_class
= cfqd
->serving_wl_class
;
1484 cfqg
->saved_wl_slice
= 0;
1486 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1488 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1489 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1490 used_sl
, cfqq
->slice_dispatch
, charge
,
1491 iops_mode(cfqd
), cfqq
->nr_sectors
);
1492 cfqg_stats_update_timeslice_used(cfqg
, used_sl
, unaccounted_sl
);
1493 cfqg_stats_set_start_empty_time(cfqg
);
1497 * cfq_init_cfqg_base - initialize base part of a cfq_group
1498 * @cfqg: cfq_group to initialize
1500 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1501 * is enabled or not.
1503 static void cfq_init_cfqg_base(struct cfq_group
*cfqg
)
1505 struct cfq_rb_root
*st
;
1508 for_each_cfqg_st(cfqg
, i
, j
, st
)
1510 RB_CLEAR_NODE(&cfqg
->rb_node
);
1512 cfqg
->ttime
.last_end_request
= jiffies
;
1515 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1516 static void cfqg_stats_init(struct cfqg_stats
*stats
)
1518 blkg_rwstat_init(&stats
->service_bytes
);
1519 blkg_rwstat_init(&stats
->serviced
);
1520 blkg_rwstat_init(&stats
->merged
);
1521 blkg_rwstat_init(&stats
->service_time
);
1522 blkg_rwstat_init(&stats
->wait_time
);
1523 blkg_rwstat_init(&stats
->queued
);
1525 blkg_stat_init(&stats
->sectors
);
1526 blkg_stat_init(&stats
->time
);
1528 #ifdef CONFIG_DEBUG_BLK_CGROUP
1529 blkg_stat_init(&stats
->unaccounted_time
);
1530 blkg_stat_init(&stats
->avg_queue_size_sum
);
1531 blkg_stat_init(&stats
->avg_queue_size_samples
);
1532 blkg_stat_init(&stats
->dequeue
);
1533 blkg_stat_init(&stats
->group_wait_time
);
1534 blkg_stat_init(&stats
->idle_time
);
1535 blkg_stat_init(&stats
->empty_time
);
1539 static void cfq_pd_init(struct blkcg_gq
*blkg
)
1541 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1543 cfq_init_cfqg_base(cfqg
);
1544 cfqg
->weight
= blkg
->blkcg
->cfq_weight
;
1545 cfqg
->leaf_weight
= blkg
->blkcg
->cfq_leaf_weight
;
1546 cfqg_stats_init(&cfqg
->stats
);
1547 cfqg_stats_init(&cfqg
->dead_stats
);
1550 static void cfq_pd_offline(struct blkcg_gq
*blkg
)
1553 * @blkg is going offline and will be ignored by
1554 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
1555 * that they don't get lost. If IOs complete after this point, the
1556 * stats for them will be lost. Oh well...
1558 cfqg_stats_xfer_dead(blkg_to_cfqg(blkg
));
1561 /* offset delta from cfqg->stats to cfqg->dead_stats */
1562 static const int dead_stats_off_delta
= offsetof(struct cfq_group
, dead_stats
) -
1563 offsetof(struct cfq_group
, stats
);
1565 /* to be used by recursive prfill, sums live and dead stats recursively */
1566 static u64
cfqg_stat_pd_recursive_sum(struct blkg_policy_data
*pd
, int off
)
1570 sum
+= blkg_stat_recursive_sum(pd
, off
);
1571 sum
+= blkg_stat_recursive_sum(pd
, off
+ dead_stats_off_delta
);
1575 /* to be used by recursive prfill, sums live and dead rwstats recursively */
1576 static struct blkg_rwstat
cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data
*pd
,
1579 struct blkg_rwstat a
, b
;
1581 a
= blkg_rwstat_recursive_sum(pd
, off
);
1582 b
= blkg_rwstat_recursive_sum(pd
, off
+ dead_stats_off_delta
);
1583 blkg_rwstat_merge(&a
, &b
);
1587 static void cfq_pd_reset_stats(struct blkcg_gq
*blkg
)
1589 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1591 cfqg_stats_reset(&cfqg
->stats
);
1592 cfqg_stats_reset(&cfqg
->dead_stats
);
1596 * Search for the cfq group current task belongs to. request_queue lock must
1599 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1600 struct blkcg
*blkcg
)
1602 struct request_queue
*q
= cfqd
->queue
;
1603 struct cfq_group
*cfqg
= NULL
;
1605 /* avoid lookup for the common case where there's no blkcg */
1606 if (blkcg
== &blkcg_root
) {
1607 cfqg
= cfqd
->root_group
;
1609 struct blkcg_gq
*blkg
;
1611 blkg
= blkg_lookup_create(blkcg
, q
);
1613 cfqg
= blkg_to_cfqg(blkg
);
1619 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1621 /* Currently, all async queues are mapped to root group */
1622 if (!cfq_cfqq_sync(cfqq
))
1623 cfqg
= cfqq
->cfqd
->root_group
;
1626 /* cfqq reference on cfqg */
1630 static u64
cfqg_prfill_weight_device(struct seq_file
*sf
,
1631 struct blkg_policy_data
*pd
, int off
)
1633 struct cfq_group
*cfqg
= pd_to_cfqg(pd
);
1635 if (!cfqg
->dev_weight
)
1637 return __blkg_prfill_u64(sf
, pd
, cfqg
->dev_weight
);
1640 static int cfqg_print_weight_device(struct seq_file
*sf
, void *v
)
1642 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)),
1643 cfqg_prfill_weight_device
, &blkcg_policy_cfq
,
1648 static u64
cfqg_prfill_leaf_weight_device(struct seq_file
*sf
,
1649 struct blkg_policy_data
*pd
, int off
)
1651 struct cfq_group
*cfqg
= pd_to_cfqg(pd
);
1653 if (!cfqg
->dev_leaf_weight
)
1655 return __blkg_prfill_u64(sf
, pd
, cfqg
->dev_leaf_weight
);
1658 static int cfqg_print_leaf_weight_device(struct seq_file
*sf
, void *v
)
1660 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)),
1661 cfqg_prfill_leaf_weight_device
, &blkcg_policy_cfq
,
1666 static int cfq_print_weight(struct seq_file
*sf
, void *v
)
1668 seq_printf(sf
, "%u\n", css_to_blkcg(seq_css(sf
))->cfq_weight
);
1672 static int cfq_print_leaf_weight(struct seq_file
*sf
, void *v
)
1674 seq_printf(sf
, "%u\n", css_to_blkcg(seq_css(sf
))->cfq_leaf_weight
);
1678 static ssize_t
__cfqg_set_weight_device(struct kernfs_open_file
*of
,
1679 char *buf
, size_t nbytes
, loff_t off
,
1680 bool is_leaf_weight
)
1682 struct blkcg
*blkcg
= css_to_blkcg(of_css(of
));
1683 struct blkg_conf_ctx ctx
;
1684 struct cfq_group
*cfqg
;
1687 ret
= blkg_conf_prep(blkcg
, &blkcg_policy_cfq
, buf
, &ctx
);
1692 cfqg
= blkg_to_cfqg(ctx
.blkg
);
1693 if (!ctx
.v
|| (ctx
.v
>= CFQ_WEIGHT_MIN
&& ctx
.v
<= CFQ_WEIGHT_MAX
)) {
1694 if (!is_leaf_weight
) {
1695 cfqg
->dev_weight
= ctx
.v
;
1696 cfqg
->new_weight
= ctx
.v
?: blkcg
->cfq_weight
;
1698 cfqg
->dev_leaf_weight
= ctx
.v
;
1699 cfqg
->new_leaf_weight
= ctx
.v
?: blkcg
->cfq_leaf_weight
;
1704 blkg_conf_finish(&ctx
);
1705 return ret
?: nbytes
;
1708 static ssize_t
cfqg_set_weight_device(struct kernfs_open_file
*of
,
1709 char *buf
, size_t nbytes
, loff_t off
)
1711 return __cfqg_set_weight_device(of
, buf
, nbytes
, off
, false);
1714 static ssize_t
cfqg_set_leaf_weight_device(struct kernfs_open_file
*of
,
1715 char *buf
, size_t nbytes
, loff_t off
)
1717 return __cfqg_set_weight_device(of
, buf
, nbytes
, off
, true);
1720 static int __cfq_set_weight(struct cgroup_subsys_state
*css
, struct cftype
*cft
,
1721 u64 val
, bool is_leaf_weight
)
1723 struct blkcg
*blkcg
= css_to_blkcg(css
);
1724 struct blkcg_gq
*blkg
;
1726 if (val
< CFQ_WEIGHT_MIN
|| val
> CFQ_WEIGHT_MAX
)
1729 spin_lock_irq(&blkcg
->lock
);
1731 if (!is_leaf_weight
)
1732 blkcg
->cfq_weight
= val
;
1734 blkcg
->cfq_leaf_weight
= val
;
1736 hlist_for_each_entry(blkg
, &blkcg
->blkg_list
, blkcg_node
) {
1737 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1742 if (!is_leaf_weight
) {
1743 if (!cfqg
->dev_weight
)
1744 cfqg
->new_weight
= blkcg
->cfq_weight
;
1746 if (!cfqg
->dev_leaf_weight
)
1747 cfqg
->new_leaf_weight
= blkcg
->cfq_leaf_weight
;
1751 spin_unlock_irq(&blkcg
->lock
);
1755 static int cfq_set_weight(struct cgroup_subsys_state
*css
, struct cftype
*cft
,
1758 return __cfq_set_weight(css
, cft
, val
, false);
1761 static int cfq_set_leaf_weight(struct cgroup_subsys_state
*css
,
1762 struct cftype
*cft
, u64 val
)
1764 return __cfq_set_weight(css
, cft
, val
, true);
1767 static int cfqg_print_stat(struct seq_file
*sf
, void *v
)
1769 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)), blkg_prfill_stat
,
1770 &blkcg_policy_cfq
, seq_cft(sf
)->private, false);
1774 static int cfqg_print_rwstat(struct seq_file
*sf
, void *v
)
1776 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)), blkg_prfill_rwstat
,
1777 &blkcg_policy_cfq
, seq_cft(sf
)->private, true);
1781 static u64
cfqg_prfill_stat_recursive(struct seq_file
*sf
,
1782 struct blkg_policy_data
*pd
, int off
)
1784 u64 sum
= cfqg_stat_pd_recursive_sum(pd
, off
);
1786 return __blkg_prfill_u64(sf
, pd
, sum
);
1789 static u64
cfqg_prfill_rwstat_recursive(struct seq_file
*sf
,
1790 struct blkg_policy_data
*pd
, int off
)
1792 struct blkg_rwstat sum
= cfqg_rwstat_pd_recursive_sum(pd
, off
);
1794 return __blkg_prfill_rwstat(sf
, pd
, &sum
);
1797 static int cfqg_print_stat_recursive(struct seq_file
*sf
, void *v
)
1799 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)),
1800 cfqg_prfill_stat_recursive
, &blkcg_policy_cfq
,
1801 seq_cft(sf
)->private, false);
1805 static int cfqg_print_rwstat_recursive(struct seq_file
*sf
, void *v
)
1807 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)),
1808 cfqg_prfill_rwstat_recursive
, &blkcg_policy_cfq
,
1809 seq_cft(sf
)->private, true);
1813 #ifdef CONFIG_DEBUG_BLK_CGROUP
1814 static u64
cfqg_prfill_avg_queue_size(struct seq_file
*sf
,
1815 struct blkg_policy_data
*pd
, int off
)
1817 struct cfq_group
*cfqg
= pd_to_cfqg(pd
);
1818 u64 samples
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_samples
);
1822 v
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_sum
);
1823 v
= div64_u64(v
, samples
);
1825 __blkg_prfill_u64(sf
, pd
, v
);
1829 /* print avg_queue_size */
1830 static int cfqg_print_avg_queue_size(struct seq_file
*sf
, void *v
)
1832 blkcg_print_blkgs(sf
, css_to_blkcg(seq_css(sf
)),
1833 cfqg_prfill_avg_queue_size
, &blkcg_policy_cfq
,
1837 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1839 static struct cftype cfq_blkcg_files
[] = {
1840 /* on root, weight is mapped to leaf_weight */
1842 .name
= "weight_device",
1843 .flags
= CFTYPE_ONLY_ON_ROOT
,
1844 .seq_show
= cfqg_print_leaf_weight_device
,
1845 .write
= cfqg_set_leaf_weight_device
,
1849 .flags
= CFTYPE_ONLY_ON_ROOT
,
1850 .seq_show
= cfq_print_leaf_weight
,
1851 .write_u64
= cfq_set_leaf_weight
,
1854 /* no such mapping necessary for !roots */
1856 .name
= "weight_device",
1857 .flags
= CFTYPE_NOT_ON_ROOT
,
1858 .seq_show
= cfqg_print_weight_device
,
1859 .write
= cfqg_set_weight_device
,
1863 .flags
= CFTYPE_NOT_ON_ROOT
,
1864 .seq_show
= cfq_print_weight
,
1865 .write_u64
= cfq_set_weight
,
1869 .name
= "leaf_weight_device",
1870 .seq_show
= cfqg_print_leaf_weight_device
,
1871 .write
= cfqg_set_leaf_weight_device
,
1874 .name
= "leaf_weight",
1875 .seq_show
= cfq_print_leaf_weight
,
1876 .write_u64
= cfq_set_leaf_weight
,
1879 /* statistics, covers only the tasks in the cfqg */
1882 .private = offsetof(struct cfq_group
, stats
.time
),
1883 .seq_show
= cfqg_print_stat
,
1887 .private = offsetof(struct cfq_group
, stats
.sectors
),
1888 .seq_show
= cfqg_print_stat
,
1891 .name
= "io_service_bytes",
1892 .private = offsetof(struct cfq_group
, stats
.service_bytes
),
1893 .seq_show
= cfqg_print_rwstat
,
1896 .name
= "io_serviced",
1897 .private = offsetof(struct cfq_group
, stats
.serviced
),
1898 .seq_show
= cfqg_print_rwstat
,
1901 .name
= "io_service_time",
1902 .private = offsetof(struct cfq_group
, stats
.service_time
),
1903 .seq_show
= cfqg_print_rwstat
,
1906 .name
= "io_wait_time",
1907 .private = offsetof(struct cfq_group
, stats
.wait_time
),
1908 .seq_show
= cfqg_print_rwstat
,
1911 .name
= "io_merged",
1912 .private = offsetof(struct cfq_group
, stats
.merged
),
1913 .seq_show
= cfqg_print_rwstat
,
1916 .name
= "io_queued",
1917 .private = offsetof(struct cfq_group
, stats
.queued
),
1918 .seq_show
= cfqg_print_rwstat
,
1921 /* the same statictics which cover the cfqg and its descendants */
1923 .name
= "time_recursive",
1924 .private = offsetof(struct cfq_group
, stats
.time
),
1925 .seq_show
= cfqg_print_stat_recursive
,
1928 .name
= "sectors_recursive",
1929 .private = offsetof(struct cfq_group
, stats
.sectors
),
1930 .seq_show
= cfqg_print_stat_recursive
,
1933 .name
= "io_service_bytes_recursive",
1934 .private = offsetof(struct cfq_group
, stats
.service_bytes
),
1935 .seq_show
= cfqg_print_rwstat_recursive
,
1938 .name
= "io_serviced_recursive",
1939 .private = offsetof(struct cfq_group
, stats
.serviced
),
1940 .seq_show
= cfqg_print_rwstat_recursive
,
1943 .name
= "io_service_time_recursive",
1944 .private = offsetof(struct cfq_group
, stats
.service_time
),
1945 .seq_show
= cfqg_print_rwstat_recursive
,
1948 .name
= "io_wait_time_recursive",
1949 .private = offsetof(struct cfq_group
, stats
.wait_time
),
1950 .seq_show
= cfqg_print_rwstat_recursive
,
1953 .name
= "io_merged_recursive",
1954 .private = offsetof(struct cfq_group
, stats
.merged
),
1955 .seq_show
= cfqg_print_rwstat_recursive
,
1958 .name
= "io_queued_recursive",
1959 .private = offsetof(struct cfq_group
, stats
.queued
),
1960 .seq_show
= cfqg_print_rwstat_recursive
,
1962 #ifdef CONFIG_DEBUG_BLK_CGROUP
1964 .name
= "avg_queue_size",
1965 .seq_show
= cfqg_print_avg_queue_size
,
1968 .name
= "group_wait_time",
1969 .private = offsetof(struct cfq_group
, stats
.group_wait_time
),
1970 .seq_show
= cfqg_print_stat
,
1973 .name
= "idle_time",
1974 .private = offsetof(struct cfq_group
, stats
.idle_time
),
1975 .seq_show
= cfqg_print_stat
,
1978 .name
= "empty_time",
1979 .private = offsetof(struct cfq_group
, stats
.empty_time
),
1980 .seq_show
= cfqg_print_stat
,
1984 .private = offsetof(struct cfq_group
, stats
.dequeue
),
1985 .seq_show
= cfqg_print_stat
,
1988 .name
= "unaccounted_time",
1989 .private = offsetof(struct cfq_group
, stats
.unaccounted_time
),
1990 .seq_show
= cfqg_print_stat
,
1992 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1995 #else /* GROUP_IOSCHED */
1996 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1997 struct blkcg
*blkcg
)
1999 return cfqd
->root_group
;
2003 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
2007 #endif /* GROUP_IOSCHED */
2010 * The cfqd->service_trees holds all pending cfq_queue's that have
2011 * requests waiting to be processed. It is sorted in the order that
2012 * we will service the queues.
2014 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2017 struct rb_node
**p
, *parent
;
2018 struct cfq_queue
*__cfqq
;
2019 unsigned long rb_key
;
2020 struct cfq_rb_root
*st
;
2024 st
= st_for(cfqq
->cfqg
, cfqq_class(cfqq
), cfqq_type(cfqq
));
2025 if (cfq_class_idle(cfqq
)) {
2026 rb_key
= CFQ_IDLE_DELAY
;
2027 parent
= rb_last(&st
->rb
);
2028 if (parent
&& parent
!= &cfqq
->rb_node
) {
2029 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
2030 rb_key
+= __cfqq
->rb_key
;
2033 } else if (!add_front
) {
2035 * Get our rb key offset. Subtract any residual slice
2036 * value carried from last service. A negative resid
2037 * count indicates slice overrun, and this should position
2038 * the next service time further away in the tree.
2040 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
2041 rb_key
-= cfqq
->slice_resid
;
2042 cfqq
->slice_resid
= 0;
2045 __cfqq
= cfq_rb_first(st
);
2046 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
2049 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
2052 * same position, nothing more to do
2054 if (rb_key
== cfqq
->rb_key
&& cfqq
->service_tree
== st
)
2057 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
2058 cfqq
->service_tree
= NULL
;
2063 cfqq
->service_tree
= st
;
2064 p
= &st
->rb
.rb_node
;
2067 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
2070 * sort by key, that represents service time.
2072 if (time_before(rb_key
, __cfqq
->rb_key
))
2073 p
= &parent
->rb_left
;
2075 p
= &parent
->rb_right
;
2081 st
->left
= &cfqq
->rb_node
;
2083 cfqq
->rb_key
= rb_key
;
2084 rb_link_node(&cfqq
->rb_node
, parent
, p
);
2085 rb_insert_color(&cfqq
->rb_node
, &st
->rb
);
2087 if (add_front
|| !new_cfqq
)
2089 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
2092 static struct cfq_queue
*
2093 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
2094 sector_t sector
, struct rb_node
**ret_parent
,
2095 struct rb_node
***rb_link
)
2097 struct rb_node
**p
, *parent
;
2098 struct cfq_queue
*cfqq
= NULL
;
2106 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
2109 * Sort strictly based on sector. Smallest to the left,
2110 * largest to the right.
2112 if (sector
> blk_rq_pos(cfqq
->next_rq
))
2113 n
= &(*p
)->rb_right
;
2114 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
2122 *ret_parent
= parent
;
2128 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2130 struct rb_node
**p
, *parent
;
2131 struct cfq_queue
*__cfqq
;
2134 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
2135 cfqq
->p_root
= NULL
;
2138 if (cfq_class_idle(cfqq
))
2143 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
2144 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
2145 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
2147 rb_link_node(&cfqq
->p_node
, parent
, p
);
2148 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
2150 cfqq
->p_root
= NULL
;
2154 * Update cfqq's position in the service tree.
2156 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2159 * Resorting requires the cfqq to be on the RR list already.
2161 if (cfq_cfqq_on_rr(cfqq
)) {
2162 cfq_service_tree_add(cfqd
, cfqq
, 0);
2163 cfq_prio_tree_add(cfqd
, cfqq
);
2168 * add to busy list of queues for service, trying to be fair in ordering
2169 * the pending list according to last request service
2171 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2173 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
2174 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2175 cfq_mark_cfqq_on_rr(cfqq
);
2176 cfqd
->busy_queues
++;
2177 if (cfq_cfqq_sync(cfqq
))
2178 cfqd
->busy_sync_queues
++;
2180 cfq_resort_rr_list(cfqd
, cfqq
);
2184 * Called when the cfqq no longer has requests pending, remove it from
2187 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2189 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
2190 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
2191 cfq_clear_cfqq_on_rr(cfqq
);
2193 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
2194 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
2195 cfqq
->service_tree
= NULL
;
2198 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
2199 cfqq
->p_root
= NULL
;
2202 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
2203 BUG_ON(!cfqd
->busy_queues
);
2204 cfqd
->busy_queues
--;
2205 if (cfq_cfqq_sync(cfqq
))
2206 cfqd
->busy_sync_queues
--;
2210 * rb tree support functions
2212 static void cfq_del_rq_rb(struct request
*rq
)
2214 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2215 const int sync
= rq_is_sync(rq
);
2217 BUG_ON(!cfqq
->queued
[sync
]);
2218 cfqq
->queued
[sync
]--;
2220 elv_rb_del(&cfqq
->sort_list
, rq
);
2222 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
2224 * Queue will be deleted from service tree when we actually
2225 * expire it later. Right now just remove it from prio tree
2229 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
2230 cfqq
->p_root
= NULL
;
2235 static void cfq_add_rq_rb(struct request
*rq
)
2237 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2238 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2239 struct request
*prev
;
2241 cfqq
->queued
[rq_is_sync(rq
)]++;
2243 elv_rb_add(&cfqq
->sort_list
, rq
);
2245 if (!cfq_cfqq_on_rr(cfqq
))
2246 cfq_add_cfqq_rr(cfqd
, cfqq
);
2249 * check if this request is a better next-serve candidate
2251 prev
= cfqq
->next_rq
;
2252 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
2255 * adjust priority tree position, if ->next_rq changes
2257 if (prev
!= cfqq
->next_rq
)
2258 cfq_prio_tree_add(cfqd
, cfqq
);
2260 BUG_ON(!cfqq
->next_rq
);
2263 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
2265 elv_rb_del(&cfqq
->sort_list
, rq
);
2266 cfqq
->queued
[rq_is_sync(rq
)]--;
2267 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
2269 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqq
->cfqd
->serving_group
,
2273 static struct request
*
2274 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
2276 struct task_struct
*tsk
= current
;
2277 struct cfq_io_cq
*cic
;
2278 struct cfq_queue
*cfqq
;
2280 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
2284 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
2286 return elv_rb_find(&cfqq
->sort_list
, bio_end_sector(bio
));
2291 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
2293 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2295 cfqd
->rq_in_driver
++;
2296 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
2297 cfqd
->rq_in_driver
);
2299 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
2302 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
2304 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2306 WARN_ON(!cfqd
->rq_in_driver
);
2307 cfqd
->rq_in_driver
--;
2308 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
2309 cfqd
->rq_in_driver
);
2312 static void cfq_remove_request(struct request
*rq
)
2314 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2316 if (cfqq
->next_rq
== rq
)
2317 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
2319 list_del_init(&rq
->queuelist
);
2322 cfqq
->cfqd
->rq_queued
--;
2323 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
2324 if (rq
->cmd_flags
& REQ_PRIO
) {
2325 WARN_ON(!cfqq
->prio_pending
);
2326 cfqq
->prio_pending
--;
2330 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
2333 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2334 struct request
*__rq
;
2336 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
2337 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
2339 return ELEVATOR_FRONT_MERGE
;
2342 return ELEVATOR_NO_MERGE
;
2345 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
2348 if (type
== ELEVATOR_FRONT_MERGE
) {
2349 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
2351 cfq_reposition_rq_rb(cfqq
, req
);
2355 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
2358 cfqg_stats_update_io_merged(RQ_CFQG(req
), bio
->bi_rw
);
2362 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
2363 struct request
*next
)
2365 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2366 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2369 * reposition in fifo if next is older than rq
2371 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
2372 time_before(next
->fifo_time
, rq
->fifo_time
) &&
2373 cfqq
== RQ_CFQQ(next
)) {
2374 list_move(&rq
->queuelist
, &next
->queuelist
);
2375 rq
->fifo_time
= next
->fifo_time
;
2378 if (cfqq
->next_rq
== next
)
2380 cfq_remove_request(next
);
2381 cfqg_stats_update_io_merged(RQ_CFQG(rq
), next
->cmd_flags
);
2383 cfqq
= RQ_CFQQ(next
);
2385 * all requests of this queue are merged to other queues, delete it
2386 * from the service tree. If it's the active_queue,
2387 * cfq_dispatch_requests() will choose to expire it or do idle
2389 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
) &&
2390 cfqq
!= cfqd
->active_queue
)
2391 cfq_del_cfqq_rr(cfqd
, cfqq
);
2394 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
2397 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2398 struct cfq_io_cq
*cic
;
2399 struct cfq_queue
*cfqq
;
2402 * Disallow merge of a sync bio into an async request.
2404 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
2408 * Lookup the cfqq that this bio will be queued with and allow
2409 * merge only if rq is queued there.
2411 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
2415 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
2416 return cfqq
== RQ_CFQQ(rq
);
2419 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2421 del_timer(&cfqd
->idle_slice_timer
);
2422 cfqg_stats_update_idle_time(cfqq
->cfqg
);
2425 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
2426 struct cfq_queue
*cfqq
)
2429 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_class:%d wl_type:%d",
2430 cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2431 cfqg_stats_update_avg_queue_size(cfqq
->cfqg
);
2432 cfqq
->slice_start
= 0;
2433 cfqq
->dispatch_start
= jiffies
;
2434 cfqq
->allocated_slice
= 0;
2435 cfqq
->slice_end
= 0;
2436 cfqq
->slice_dispatch
= 0;
2437 cfqq
->nr_sectors
= 0;
2439 cfq_clear_cfqq_wait_request(cfqq
);
2440 cfq_clear_cfqq_must_dispatch(cfqq
);
2441 cfq_clear_cfqq_must_alloc_slice(cfqq
);
2442 cfq_clear_cfqq_fifo_expire(cfqq
);
2443 cfq_mark_cfqq_slice_new(cfqq
);
2445 cfq_del_timer(cfqd
, cfqq
);
2448 cfqd
->active_queue
= cfqq
;
2452 * current cfqq expired its slice (or was too idle), select new one
2455 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2458 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
2460 if (cfq_cfqq_wait_request(cfqq
))
2461 cfq_del_timer(cfqd
, cfqq
);
2463 cfq_clear_cfqq_wait_request(cfqq
);
2464 cfq_clear_cfqq_wait_busy(cfqq
);
2467 * If this cfqq is shared between multiple processes, check to
2468 * make sure that those processes are still issuing I/Os within
2469 * the mean seek distance. If not, it may be time to break the
2470 * queues apart again.
2472 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
2473 cfq_mark_cfqq_split_coop(cfqq
);
2476 * store what was left of this slice, if the queue idled/timed out
2479 if (cfq_cfqq_slice_new(cfqq
))
2480 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
2482 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
2483 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
2486 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
2488 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
2489 cfq_del_cfqq_rr(cfqd
, cfqq
);
2491 cfq_resort_rr_list(cfqd
, cfqq
);
2493 if (cfqq
== cfqd
->active_queue
)
2494 cfqd
->active_queue
= NULL
;
2496 if (cfqd
->active_cic
) {
2497 put_io_context(cfqd
->active_cic
->icq
.ioc
);
2498 cfqd
->active_cic
= NULL
;
2502 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
2504 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2507 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
2511 * Get next queue for service. Unless we have a queue preemption,
2512 * we'll simply select the first cfqq in the service tree.
2514 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
2516 struct cfq_rb_root
*st
= st_for(cfqd
->serving_group
,
2517 cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2519 if (!cfqd
->rq_queued
)
2522 /* There is nothing to dispatch */
2525 if (RB_EMPTY_ROOT(&st
->rb
))
2527 return cfq_rb_first(st
);
2530 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
2532 struct cfq_group
*cfqg
;
2533 struct cfq_queue
*cfqq
;
2535 struct cfq_rb_root
*st
;
2537 if (!cfqd
->rq_queued
)
2540 cfqg
= cfq_get_next_cfqg(cfqd
);
2544 for_each_cfqg_st(cfqg
, i
, j
, st
)
2545 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
2551 * Get and set a new active queue for service.
2553 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
2554 struct cfq_queue
*cfqq
)
2557 cfqq
= cfq_get_next_queue(cfqd
);
2559 __cfq_set_active_queue(cfqd
, cfqq
);
2563 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
2566 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
2567 return blk_rq_pos(rq
) - cfqd
->last_position
;
2569 return cfqd
->last_position
- blk_rq_pos(rq
);
2572 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2575 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
2578 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
2579 struct cfq_queue
*cur_cfqq
)
2581 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
2582 struct rb_node
*parent
, *node
;
2583 struct cfq_queue
*__cfqq
;
2584 sector_t sector
= cfqd
->last_position
;
2586 if (RB_EMPTY_ROOT(root
))
2590 * First, if we find a request starting at the end of the last
2591 * request, choose it.
2593 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
2598 * If the exact sector wasn't found, the parent of the NULL leaf
2599 * will contain the closest sector.
2601 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
2602 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2605 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
2606 node
= rb_next(&__cfqq
->p_node
);
2608 node
= rb_prev(&__cfqq
->p_node
);
2612 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
2613 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2621 * cur_cfqq - passed in so that we don't decide that the current queue is
2622 * closely cooperating with itself.
2624 * So, basically we're assuming that that cur_cfqq has dispatched at least
2625 * one request, and that cfqd->last_position reflects a position on the disk
2626 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2629 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
2630 struct cfq_queue
*cur_cfqq
)
2632 struct cfq_queue
*cfqq
;
2634 if (cfq_class_idle(cur_cfqq
))
2636 if (!cfq_cfqq_sync(cur_cfqq
))
2638 if (CFQQ_SEEKY(cur_cfqq
))
2642 * Don't search priority tree if it's the only queue in the group.
2644 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
2648 * We should notice if some of the queues are cooperating, eg
2649 * working closely on the same area of the disk. In that case,
2650 * we can group them together and don't waste time idling.
2652 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
2656 /* If new queue belongs to different cfq_group, don't choose it */
2657 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
2661 * It only makes sense to merge sync queues.
2663 if (!cfq_cfqq_sync(cfqq
))
2665 if (CFQQ_SEEKY(cfqq
))
2669 * Do not merge queues of different priority classes
2671 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
2678 * Determine whether we should enforce idle window for this queue.
2681 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2683 enum wl_class_t wl_class
= cfqq_class(cfqq
);
2684 struct cfq_rb_root
*st
= cfqq
->service_tree
;
2689 if (!cfqd
->cfq_slice_idle
)
2692 /* We never do for idle class queues. */
2693 if (wl_class
== IDLE_WORKLOAD
)
2696 /* We do for queues that were marked with idle window flag. */
2697 if (cfq_cfqq_idle_window(cfqq
) &&
2698 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
2702 * Otherwise, we do only if they are the last ones
2703 * in their service tree.
2705 if (st
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
2706 !cfq_io_thinktime_big(cfqd
, &st
->ttime
, false))
2708 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d", st
->count
);
2712 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2714 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2715 struct cfq_io_cq
*cic
;
2716 unsigned long sl
, group_idle
= 0;
2719 * SSD device without seek penalty, disable idling. But only do so
2720 * for devices that support queuing, otherwise we still have a problem
2721 * with sync vs async workloads.
2723 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2726 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2727 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2730 * idle is disabled, either manually or by past process history
2732 if (!cfq_should_idle(cfqd
, cfqq
)) {
2733 /* no queue idling. Check for group idling */
2734 if (cfqd
->cfq_group_idle
)
2735 group_idle
= cfqd
->cfq_group_idle
;
2741 * still active requests from this queue, don't idle
2743 if (cfqq
->dispatched
)
2747 * task has exited, don't wait
2749 cic
= cfqd
->active_cic
;
2750 if (!cic
|| !atomic_read(&cic
->icq
.ioc
->active_ref
))
2754 * If our average think time is larger than the remaining time
2755 * slice, then don't idle. This avoids overrunning the allotted
2758 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2759 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2760 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2761 cic
->ttime
.ttime_mean
);
2765 /* There are other queues in the group, don't do group idle */
2766 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2769 cfq_mark_cfqq_wait_request(cfqq
);
2772 sl
= cfqd
->cfq_group_idle
;
2774 sl
= cfqd
->cfq_slice_idle
;
2776 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2777 cfqg_stats_set_start_idle_time(cfqq
->cfqg
);
2778 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2779 group_idle
? 1 : 0);
2783 * Move request from internal lists to the request queue dispatch list.
2785 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2787 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2788 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2790 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2792 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2793 cfq_remove_request(rq
);
2795 (RQ_CFQG(rq
))->dispatched
++;
2796 elv_dispatch_sort(q
, rq
);
2798 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2799 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2800 cfqg_stats_update_dispatch(cfqq
->cfqg
, blk_rq_bytes(rq
), rq
->cmd_flags
);
2804 * return expired entry, or NULL to just start from scratch in rbtree
2806 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2808 struct request
*rq
= NULL
;
2810 if (cfq_cfqq_fifo_expire(cfqq
))
2813 cfq_mark_cfqq_fifo_expire(cfqq
);
2815 if (list_empty(&cfqq
->fifo
))
2818 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2819 if (time_before(jiffies
, rq
->fifo_time
))
2822 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2827 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2829 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2831 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2833 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2837 * Must be called with the queue_lock held.
2839 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2841 int process_refs
, io_refs
;
2843 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2844 process_refs
= cfqq
->ref
- io_refs
;
2845 BUG_ON(process_refs
< 0);
2846 return process_refs
;
2849 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2851 int process_refs
, new_process_refs
;
2852 struct cfq_queue
*__cfqq
;
2855 * If there are no process references on the new_cfqq, then it is
2856 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2857 * chain may have dropped their last reference (not just their
2858 * last process reference).
2860 if (!cfqq_process_refs(new_cfqq
))
2863 /* Avoid a circular list and skip interim queue merges */
2864 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2870 process_refs
= cfqq_process_refs(cfqq
);
2871 new_process_refs
= cfqq_process_refs(new_cfqq
);
2873 * If the process for the cfqq has gone away, there is no
2874 * sense in merging the queues.
2876 if (process_refs
== 0 || new_process_refs
== 0)
2880 * Merge in the direction of the lesser amount of work.
2882 if (new_process_refs
>= process_refs
) {
2883 cfqq
->new_cfqq
= new_cfqq
;
2884 new_cfqq
->ref
+= process_refs
;
2886 new_cfqq
->new_cfqq
= cfqq
;
2887 cfqq
->ref
+= new_process_refs
;
2891 static enum wl_type_t
cfq_choose_wl_type(struct cfq_data
*cfqd
,
2892 struct cfq_group
*cfqg
, enum wl_class_t wl_class
)
2894 struct cfq_queue
*queue
;
2896 bool key_valid
= false;
2897 unsigned long lowest_key
= 0;
2898 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2900 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2901 /* select the one with lowest rb_key */
2902 queue
= cfq_rb_first(st_for(cfqg
, wl_class
, i
));
2904 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2905 lowest_key
= queue
->rb_key
;
2915 choose_wl_class_and_type(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2919 struct cfq_rb_root
*st
;
2920 unsigned group_slice
;
2921 enum wl_class_t original_class
= cfqd
->serving_wl_class
;
2923 /* Choose next priority. RT > BE > IDLE */
2924 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2925 cfqd
->serving_wl_class
= RT_WORKLOAD
;
2926 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2927 cfqd
->serving_wl_class
= BE_WORKLOAD
;
2929 cfqd
->serving_wl_class
= IDLE_WORKLOAD
;
2930 cfqd
->workload_expires
= jiffies
+ 1;
2934 if (original_class
!= cfqd
->serving_wl_class
)
2938 * For RT and BE, we have to choose also the type
2939 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2942 st
= st_for(cfqg
, cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2946 * check workload expiration, and that we still have other queues ready
2948 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2952 /* otherwise select new workload type */
2953 cfqd
->serving_wl_type
= cfq_choose_wl_type(cfqd
, cfqg
,
2954 cfqd
->serving_wl_class
);
2955 st
= st_for(cfqg
, cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2959 * the workload slice is computed as a fraction of target latency
2960 * proportional to the number of queues in that workload, over
2961 * all the queues in the same priority class
2963 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2965 slice
= group_slice
* count
/
2966 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_wl_class
],
2967 cfq_group_busy_queues_wl(cfqd
->serving_wl_class
, cfqd
,
2970 if (cfqd
->serving_wl_type
== ASYNC_WORKLOAD
) {
2974 * Async queues are currently system wide. Just taking
2975 * proportion of queues with-in same group will lead to higher
2976 * async ratio system wide as generally root group is going
2977 * to have higher weight. A more accurate thing would be to
2978 * calculate system wide asnc/sync ratio.
2980 tmp
= cfqd
->cfq_target_latency
*
2981 cfqg_busy_async_queues(cfqd
, cfqg
);
2982 tmp
= tmp
/cfqd
->busy_queues
;
2983 slice
= min_t(unsigned, slice
, tmp
);
2985 /* async workload slice is scaled down according to
2986 * the sync/async slice ratio. */
2987 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2989 /* sync workload slice is at least 2 * cfq_slice_idle */
2990 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2992 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2993 cfq_log(cfqd
, "workload slice:%d", slice
);
2994 cfqd
->workload_expires
= jiffies
+ slice
;
2997 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2999 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
3000 struct cfq_group
*cfqg
;
3002 if (RB_EMPTY_ROOT(&st
->rb
))
3004 cfqg
= cfq_rb_first_group(st
);
3005 update_min_vdisktime(st
);
3009 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
3011 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
3013 cfqd
->serving_group
= cfqg
;
3015 /* Restore the workload type data */
3016 if (cfqg
->saved_wl_slice
) {
3017 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_wl_slice
;
3018 cfqd
->serving_wl_type
= cfqg
->saved_wl_type
;
3019 cfqd
->serving_wl_class
= cfqg
->saved_wl_class
;
3021 cfqd
->workload_expires
= jiffies
- 1;
3023 choose_wl_class_and_type(cfqd
, cfqg
);
3027 * Select a queue for service. If we have a current active queue,
3028 * check whether to continue servicing it, or retrieve and set a new one.
3030 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
3032 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
3034 cfqq
= cfqd
->active_queue
;
3038 if (!cfqd
->rq_queued
)
3042 * We were waiting for group to get backlogged. Expire the queue
3044 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
3048 * The active queue has run out of time, expire it and select new.
3050 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
3052 * If slice had not expired at the completion of last request
3053 * we might not have turned on wait_busy flag. Don't expire
3054 * the queue yet. Allow the group to get backlogged.
3056 * The very fact that we have used the slice, that means we
3057 * have been idling all along on this queue and it should be
3058 * ok to wait for this request to complete.
3060 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
3061 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
3065 goto check_group_idle
;
3069 * The active queue has requests and isn't expired, allow it to
3072 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3076 * If another queue has a request waiting within our mean seek
3077 * distance, let it run. The expire code will check for close
3078 * cooperators and put the close queue at the front of the service
3079 * tree. If possible, merge the expiring queue with the new cfqq.
3081 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
3083 if (!cfqq
->new_cfqq
)
3084 cfq_setup_merge(cfqq
, new_cfqq
);
3089 * No requests pending. If the active queue still has requests in
3090 * flight or is idling for a new request, allow either of these
3091 * conditions to happen (or time out) before selecting a new queue.
3093 if (timer_pending(&cfqd
->idle_slice_timer
)) {
3099 * This is a deep seek queue, but the device is much faster than
3100 * the queue can deliver, don't idle
3102 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
3103 (cfq_cfqq_slice_new(cfqq
) ||
3104 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
3105 cfq_clear_cfqq_deep(cfqq
);
3106 cfq_clear_cfqq_idle_window(cfqq
);
3109 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
3115 * If group idle is enabled and there are requests dispatched from
3116 * this group, wait for requests to complete.
3119 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
3120 cfqq
->cfqg
->dispatched
&&
3121 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
3127 cfq_slice_expired(cfqd
, 0);
3130 * Current queue expired. Check if we have to switch to a new
3134 cfq_choose_cfqg(cfqd
);
3136 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
3141 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
3145 while (cfqq
->next_rq
) {
3146 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
3150 BUG_ON(!list_empty(&cfqq
->fifo
));
3152 /* By default cfqq is not expired if it is empty. Do it explicitly */
3153 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
3158 * Drain our current requests. Used for barriers and when switching
3159 * io schedulers on-the-fly.
3161 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
3163 struct cfq_queue
*cfqq
;
3166 /* Expire the timeslice of the current active queue first */
3167 cfq_slice_expired(cfqd
, 0);
3168 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
3169 __cfq_set_active_queue(cfqd
, cfqq
);
3170 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
3173 BUG_ON(cfqd
->busy_queues
);
3175 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
3179 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
3180 struct cfq_queue
*cfqq
)
3182 /* the queue hasn't finished any request, can't estimate */
3183 if (cfq_cfqq_slice_new(cfqq
))
3185 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
3192 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3194 unsigned int max_dispatch
;
3197 * Drain async requests before we start sync IO
3199 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
3203 * If this is an async queue and we have sync IO in flight, let it wait
3205 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
3208 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
3209 if (cfq_class_idle(cfqq
))
3213 * Does this cfqq already have too much IO in flight?
3215 if (cfqq
->dispatched
>= max_dispatch
) {
3216 bool promote_sync
= false;
3218 * idle queue must always only have a single IO in flight
3220 if (cfq_class_idle(cfqq
))
3224 * If there is only one sync queue
3225 * we can ignore async queue here and give the sync
3226 * queue no dispatch limit. The reason is a sync queue can
3227 * preempt async queue, limiting the sync queue doesn't make
3228 * sense. This is useful for aiostress test.
3230 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
3231 promote_sync
= true;
3234 * We have other queues, don't allow more IO from this one
3236 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
3241 * Sole queue user, no limit
3243 if (cfqd
->busy_queues
== 1 || promote_sync
)
3247 * Normally we start throttling cfqq when cfq_quantum/2
3248 * requests have been dispatched. But we can drive
3249 * deeper queue depths at the beginning of slice
3250 * subjected to upper limit of cfq_quantum.
3252 max_dispatch
= cfqd
->cfq_quantum
;
3256 * Async queues must wait a bit before being allowed dispatch.
3257 * We also ramp up the dispatch depth gradually for async IO,
3258 * based on the last sync IO we serviced
3260 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
3261 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
3264 depth
= last_sync
/ cfqd
->cfq_slice
[1];
3265 if (!depth
&& !cfqq
->dispatched
)
3267 if (depth
< max_dispatch
)
3268 max_dispatch
= depth
;
3272 * If we're below the current max, allow a dispatch
3274 return cfqq
->dispatched
< max_dispatch
;
3278 * Dispatch a request from cfqq, moving them to the request queue
3281 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3285 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
3287 if (!cfq_may_dispatch(cfqd
, cfqq
))
3291 * follow expired path, else get first next available
3293 rq
= cfq_check_fifo(cfqq
);
3298 * insert request into driver dispatch list
3300 cfq_dispatch_insert(cfqd
->queue
, rq
);
3302 if (!cfqd
->active_cic
) {
3303 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3305 atomic_long_inc(&cic
->icq
.ioc
->refcount
);
3306 cfqd
->active_cic
= cic
;
3313 * Find the cfqq that we need to service and move a request from that to the
3316 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
3318 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3319 struct cfq_queue
*cfqq
;
3321 if (!cfqd
->busy_queues
)
3324 if (unlikely(force
))
3325 return cfq_forced_dispatch(cfqd
);
3327 cfqq
= cfq_select_queue(cfqd
);
3332 * Dispatch a request from this cfqq, if it is allowed
3334 if (!cfq_dispatch_request(cfqd
, cfqq
))
3337 cfqq
->slice_dispatch
++;
3338 cfq_clear_cfqq_must_dispatch(cfqq
);
3341 * expire an async queue immediately if it has used up its slice. idle
3342 * queue always expire after 1 dispatch round.
3344 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
3345 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
3346 cfq_class_idle(cfqq
))) {
3347 cfqq
->slice_end
= jiffies
+ 1;
3348 cfq_slice_expired(cfqd
, 0);
3351 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
3356 * task holds one reference to the queue, dropped when task exits. each rq
3357 * in-flight on this queue also holds a reference, dropped when rq is freed.
3359 * Each cfq queue took a reference on the parent group. Drop it now.
3360 * queue lock must be held here.
3362 static void cfq_put_queue(struct cfq_queue
*cfqq
)
3364 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3365 struct cfq_group
*cfqg
;
3367 BUG_ON(cfqq
->ref
<= 0);
3373 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
3374 BUG_ON(rb_first(&cfqq
->sort_list
));
3375 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
3378 if (unlikely(cfqd
->active_queue
== cfqq
)) {
3379 __cfq_slice_expired(cfqd
, cfqq
, 0);
3380 cfq_schedule_dispatch(cfqd
);
3383 BUG_ON(cfq_cfqq_on_rr(cfqq
));
3384 kmem_cache_free(cfq_pool
, cfqq
);
3388 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
3390 struct cfq_queue
*__cfqq
, *next
;
3393 * If this queue was scheduled to merge with another queue, be
3394 * sure to drop the reference taken on that queue (and others in
3395 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
3397 __cfqq
= cfqq
->new_cfqq
;
3399 if (__cfqq
== cfqq
) {
3400 WARN(1, "cfqq->new_cfqq loop detected\n");
3403 next
= __cfqq
->new_cfqq
;
3404 cfq_put_queue(__cfqq
);
3409 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3411 if (unlikely(cfqq
== cfqd
->active_queue
)) {
3412 __cfq_slice_expired(cfqd
, cfqq
, 0);
3413 cfq_schedule_dispatch(cfqd
);
3416 cfq_put_cooperator(cfqq
);
3418 cfq_put_queue(cfqq
);
3421 static void cfq_init_icq(struct io_cq
*icq
)
3423 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3425 cic
->ttime
.last_end_request
= jiffies
;
3428 static void cfq_exit_icq(struct io_cq
*icq
)
3430 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3431 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3433 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
3434 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
3435 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
3438 if (cic
->cfqq
[BLK_RW_SYNC
]) {
3439 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
3440 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
3444 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct cfq_io_cq
*cic
)
3446 struct task_struct
*tsk
= current
;
3449 if (!cfq_cfqq_prio_changed(cfqq
))
3452 ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3453 switch (ioprio_class
) {
3455 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
3456 case IOPRIO_CLASS_NONE
:
3458 * no prio set, inherit CPU scheduling settings
3460 cfqq
->ioprio
= task_nice_ioprio(tsk
);
3461 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
3463 case IOPRIO_CLASS_RT
:
3464 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3465 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
3467 case IOPRIO_CLASS_BE
:
3468 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3469 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3471 case IOPRIO_CLASS_IDLE
:
3472 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
3474 cfq_clear_cfqq_idle_window(cfqq
);
3479 * keep track of original prio settings in case we have to temporarily
3480 * elevate the priority of this queue
3482 cfqq
->org_ioprio
= cfqq
->ioprio
;
3483 cfq_clear_cfqq_prio_changed(cfqq
);
3486 static void check_ioprio_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3488 int ioprio
= cic
->icq
.ioc
->ioprio
;
3489 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3490 struct cfq_queue
*cfqq
;
3493 * Check whether ioprio has changed. The condition may trigger
3494 * spuriously on a newly created cic but there's no harm.
3496 if (unlikely(!cfqd
) || likely(cic
->ioprio
== ioprio
))
3499 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
3501 struct cfq_queue
*new_cfqq
;
3502 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
, bio
,
3505 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
3506 cfq_put_queue(cfqq
);
3510 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
3512 cfq_mark_cfqq_prio_changed(cfqq
);
3514 cic
->ioprio
= ioprio
;
3517 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3518 pid_t pid
, bool is_sync
)
3520 RB_CLEAR_NODE(&cfqq
->rb_node
);
3521 RB_CLEAR_NODE(&cfqq
->p_node
);
3522 INIT_LIST_HEAD(&cfqq
->fifo
);
3527 cfq_mark_cfqq_prio_changed(cfqq
);
3530 if (!cfq_class_idle(cfqq
))
3531 cfq_mark_cfqq_idle_window(cfqq
);
3532 cfq_mark_cfqq_sync(cfqq
);
3537 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3538 static void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3540 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3541 struct cfq_queue
*sync_cfqq
;
3545 id
= bio_blkcg(bio
)->id
;
3549 * Check whether blkcg has changed. The condition may trigger
3550 * spuriously on a newly created cic but there's no harm.
3552 if (unlikely(!cfqd
) || likely(cic
->blkcg_id
== id
))
3555 sync_cfqq
= cic_to_cfqq(cic
, 1);
3558 * Drop reference to sync queue. A new sync queue will be
3559 * assigned in new group upon arrival of a fresh request.
3561 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
3562 cic_set_cfqq(cic
, NULL
, 1);
3563 cfq_put_queue(sync_cfqq
);
3569 static inline void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
) { }
3570 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3572 static struct cfq_queue
*
3573 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3574 struct bio
*bio
, gfp_t gfp_mask
)
3576 struct blkcg
*blkcg
;
3577 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
3578 struct cfq_group
*cfqg
;
3583 blkcg
= bio_blkcg(bio
);
3584 cfqg
= cfq_lookup_create_cfqg(cfqd
, blkcg
);
3585 cfqq
= cic_to_cfqq(cic
, is_sync
);
3588 * Always try a new alloc if we fell back to the OOM cfqq
3589 * originally, since it should just be a temporary situation.
3591 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3596 } else if (gfp_mask
& __GFP_WAIT
) {
3598 spin_unlock_irq(cfqd
->queue
->queue_lock
);
3599 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
3600 gfp_mask
| __GFP_ZERO
,
3602 spin_lock_irq(cfqd
->queue
->queue_lock
);
3606 return &cfqd
->oom_cfqq
;
3608 cfqq
= kmem_cache_alloc_node(cfq_pool
,
3609 gfp_mask
| __GFP_ZERO
,
3614 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
3615 cfq_init_prio_data(cfqq
, cic
);
3616 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
3617 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
3619 cfqq
= &cfqd
->oom_cfqq
;
3623 kmem_cache_free(cfq_pool
, new_cfqq
);
3629 static struct cfq_queue
**
3630 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
3632 switch (ioprio_class
) {
3633 case IOPRIO_CLASS_RT
:
3634 return &cfqd
->async_cfqq
[0][ioprio
];
3635 case IOPRIO_CLASS_NONE
:
3636 ioprio
= IOPRIO_NORM
;
3638 case IOPRIO_CLASS_BE
:
3639 return &cfqd
->async_cfqq
[1][ioprio
];
3640 case IOPRIO_CLASS_IDLE
:
3641 return &cfqd
->async_idle_cfqq
;
3647 static struct cfq_queue
*
3648 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3649 struct bio
*bio
, gfp_t gfp_mask
)
3651 const int ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3652 const int ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3653 struct cfq_queue
**async_cfqq
= NULL
;
3654 struct cfq_queue
*cfqq
= NULL
;
3657 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
3662 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3665 * pin the queue now that it's allocated, scheduler exit will prune it
3667 if (!is_sync
&& !(*async_cfqq
)) {
3677 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3679 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3680 elapsed
= min(elapsed
, 2UL * slice_idle
);
3682 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3683 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3684 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3688 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3689 struct cfq_io_cq
*cic
)
3691 if (cfq_cfqq_sync(cfqq
)) {
3692 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3693 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3694 cfqd
->cfq_slice_idle
);
3696 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3697 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3702 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3706 sector_t n_sec
= blk_rq_sectors(rq
);
3707 if (cfqq
->last_request_pos
) {
3708 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3709 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3711 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3714 cfqq
->seek_history
<<= 1;
3715 if (blk_queue_nonrot(cfqd
->queue
))
3716 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3718 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3722 * Disable idle window if the process thinks too long or seeks so much that
3726 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3727 struct cfq_io_cq
*cic
)
3729 int old_idle
, enable_idle
;
3732 * Don't idle for async or idle io prio class
3734 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3737 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3739 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3740 cfq_mark_cfqq_deep(cfqq
);
3742 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3744 else if (!atomic_read(&cic
->icq
.ioc
->active_ref
) ||
3745 !cfqd
->cfq_slice_idle
||
3746 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3748 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3749 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3755 if (old_idle
!= enable_idle
) {
3756 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3758 cfq_mark_cfqq_idle_window(cfqq
);
3760 cfq_clear_cfqq_idle_window(cfqq
);
3765 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3766 * no or if we aren't sure, a 1 will cause a preempt.
3769 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3772 struct cfq_queue
*cfqq
;
3774 cfqq
= cfqd
->active_queue
;
3778 if (cfq_class_idle(new_cfqq
))
3781 if (cfq_class_idle(cfqq
))
3785 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3787 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3791 * if the new request is sync, but the currently running queue is
3792 * not, let the sync request have priority.
3794 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3797 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3800 if (cfq_slice_used(cfqq
))
3803 /* Allow preemption only if we are idling on sync-noidle tree */
3804 if (cfqd
->serving_wl_type
== SYNC_NOIDLE_WORKLOAD
&&
3805 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3806 new_cfqq
->service_tree
->count
== 2 &&
3807 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3811 * So both queues are sync. Let the new request get disk time if
3812 * it's a metadata request and the current queue is doing regular IO.
3814 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3818 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3820 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3823 /* An idle queue should not be idle now for some reason */
3824 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3827 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3831 * if this request is as-good as one we would expect from the
3832 * current cfqq, let it preempt
3834 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3841 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3842 * let it have half of its nominal slice.
3844 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3846 enum wl_type_t old_type
= cfqq_type(cfqd
->active_queue
);
3848 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3849 cfq_slice_expired(cfqd
, 1);
3852 * workload type is changed, don't save slice, otherwise preempt
3855 if (old_type
!= cfqq_type(cfqq
))
3856 cfqq
->cfqg
->saved_wl_slice
= 0;
3859 * Put the new queue at the front of the of the current list,
3860 * so we know that it will be selected next.
3862 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3864 cfq_service_tree_add(cfqd
, cfqq
, 1);
3866 cfqq
->slice_end
= 0;
3867 cfq_mark_cfqq_slice_new(cfqq
);
3871 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3872 * something we should do about it
3875 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3878 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3881 if (rq
->cmd_flags
& REQ_PRIO
)
3882 cfqq
->prio_pending
++;
3884 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3885 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3886 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3888 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3890 if (cfqq
== cfqd
->active_queue
) {
3892 * Remember that we saw a request from this process, but
3893 * don't start queuing just yet. Otherwise we risk seeing lots
3894 * of tiny requests, because we disrupt the normal plugging
3895 * and merging. If the request is already larger than a single
3896 * page, let it rip immediately. For that case we assume that
3897 * merging is already done. Ditto for a busy system that
3898 * has other work pending, don't risk delaying until the
3899 * idle timer unplug to continue working.
3901 if (cfq_cfqq_wait_request(cfqq
)) {
3902 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3903 cfqd
->busy_queues
> 1) {
3904 cfq_del_timer(cfqd
, cfqq
);
3905 cfq_clear_cfqq_wait_request(cfqq
);
3906 __blk_run_queue(cfqd
->queue
);
3908 cfqg_stats_update_idle_time(cfqq
->cfqg
);
3909 cfq_mark_cfqq_must_dispatch(cfqq
);
3912 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3914 * not the active queue - expire current slice if it is
3915 * idle and has expired it's mean thinktime or this new queue
3916 * has some old slice time left and is of higher priority or
3917 * this new queue is RT and the current one is BE
3919 cfq_preempt_queue(cfqd
, cfqq
);
3920 __blk_run_queue(cfqd
->queue
);
3924 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3926 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3927 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3929 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3930 cfq_init_prio_data(cfqq
, RQ_CIC(rq
));
3932 rq
->fifo_time
= jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)];
3933 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3935 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqd
->serving_group
,
3937 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3941 * Update hw_tag based on peak queue depth over 50 samples under
3944 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3946 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3948 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3949 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3951 if (cfqd
->hw_tag
== 1)
3954 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3955 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3959 * If active queue hasn't enough requests and can idle, cfq might not
3960 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3963 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3964 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3965 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3968 if (cfqd
->hw_tag_samples
++ < 50)
3971 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3977 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3979 struct cfq_io_cq
*cic
= cfqd
->active_cic
;
3981 /* If the queue already has requests, don't wait */
3982 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3985 /* If there are other queues in the group, don't wait */
3986 if (cfqq
->cfqg
->nr_cfqq
> 1)
3989 /* the only queue in the group, but think time is big */
3990 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3993 if (cfq_slice_used(cfqq
))
3996 /* if slice left is less than think time, wait busy */
3997 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3998 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
4002 * If think times is less than a jiffy than ttime_mean=0 and above
4003 * will not be true. It might happen that slice has not expired yet
4004 * but will expire soon (4-5 ns) during select_queue(). To cover the
4005 * case where think time is less than a jiffy, mark the queue wait
4006 * busy if only 1 jiffy is left in the slice.
4008 if (cfqq
->slice_end
- jiffies
== 1)
4014 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
4016 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
4017 struct cfq_data
*cfqd
= cfqq
->cfqd
;
4018 const int sync
= rq_is_sync(rq
);
4022 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
4023 !!(rq
->cmd_flags
& REQ_NOIDLE
));
4025 cfq_update_hw_tag(cfqd
);
4027 WARN_ON(!cfqd
->rq_in_driver
);
4028 WARN_ON(!cfqq
->dispatched
);
4029 cfqd
->rq_in_driver
--;
4031 (RQ_CFQG(rq
))->dispatched
--;
4032 cfqg_stats_update_completion(cfqq
->cfqg
, rq_start_time_ns(rq
),
4033 rq_io_start_time_ns(rq
), rq
->cmd_flags
);
4035 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
4038 struct cfq_rb_root
*st
;
4040 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
4042 if (cfq_cfqq_on_rr(cfqq
))
4043 st
= cfqq
->service_tree
;
4045 st
= st_for(cfqq
->cfqg
, cfqq_class(cfqq
),
4048 st
->ttime
.last_end_request
= now
;
4049 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
4050 cfqd
->last_delayed_sync
= now
;
4053 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4054 cfqq
->cfqg
->ttime
.last_end_request
= now
;
4058 * If this is the active queue, check if it needs to be expired,
4059 * or if we want to idle in case it has no pending requests.
4061 if (cfqd
->active_queue
== cfqq
) {
4062 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
4064 if (cfq_cfqq_slice_new(cfqq
)) {
4065 cfq_set_prio_slice(cfqd
, cfqq
);
4066 cfq_clear_cfqq_slice_new(cfqq
);
4070 * Should we wait for next request to come in before we expire
4073 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
4074 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
4075 if (!cfqd
->cfq_slice_idle
)
4076 extend_sl
= cfqd
->cfq_group_idle
;
4077 cfqq
->slice_end
= jiffies
+ extend_sl
;
4078 cfq_mark_cfqq_wait_busy(cfqq
);
4079 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
4083 * Idling is not enabled on:
4085 * - idle-priority queues
4087 * - queues with still some requests queued
4088 * - when there is a close cooperator
4090 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
4091 cfq_slice_expired(cfqd
, 1);
4092 else if (sync
&& cfqq_empty
&&
4093 !cfq_close_cooperator(cfqd
, cfqq
)) {
4094 cfq_arm_slice_timer(cfqd
);
4098 if (!cfqd
->rq_in_driver
)
4099 cfq_schedule_dispatch(cfqd
);
4102 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
4104 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
4105 cfq_mark_cfqq_must_alloc_slice(cfqq
);
4106 return ELV_MQUEUE_MUST
;
4109 return ELV_MQUEUE_MAY
;
4112 static int cfq_may_queue(struct request_queue
*q
, int rw
)
4114 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
4115 struct task_struct
*tsk
= current
;
4116 struct cfq_io_cq
*cic
;
4117 struct cfq_queue
*cfqq
;
4120 * don't force setup of a queue from here, as a call to may_queue
4121 * does not necessarily imply that a request actually will be queued.
4122 * so just lookup a possibly existing queue, or return 'may queue'
4125 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
4127 return ELV_MQUEUE_MAY
;
4129 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
4131 cfq_init_prio_data(cfqq
, cic
);
4133 return __cfq_may_queue(cfqq
);
4136 return ELV_MQUEUE_MAY
;
4140 * queue lock held here
4142 static void cfq_put_request(struct request
*rq
)
4144 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
4147 const int rw
= rq_data_dir(rq
);
4149 BUG_ON(!cfqq
->allocated
[rw
]);
4150 cfqq
->allocated
[rw
]--;
4152 /* Put down rq reference on cfqg */
4153 cfqg_put(RQ_CFQG(rq
));
4154 rq
->elv
.priv
[0] = NULL
;
4155 rq
->elv
.priv
[1] = NULL
;
4157 cfq_put_queue(cfqq
);
4161 static struct cfq_queue
*
4162 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_cq
*cic
,
4163 struct cfq_queue
*cfqq
)
4165 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
4166 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
4167 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
4168 cfq_put_queue(cfqq
);
4169 return cic_to_cfqq(cic
, 1);
4173 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4174 * was the last process referring to said cfqq.
4176 static struct cfq_queue
*
4177 split_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
)
4179 if (cfqq_process_refs(cfqq
) == 1) {
4180 cfqq
->pid
= current
->pid
;
4181 cfq_clear_cfqq_coop(cfqq
);
4182 cfq_clear_cfqq_split_coop(cfqq
);
4186 cic_set_cfqq(cic
, NULL
, 1);
4188 cfq_put_cooperator(cfqq
);
4190 cfq_put_queue(cfqq
);
4194 * Allocate cfq data structures associated with this request.
4197 cfq_set_request(struct request_queue
*q
, struct request
*rq
, struct bio
*bio
,
4200 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
4201 struct cfq_io_cq
*cic
= icq_to_cic(rq
->elv
.icq
);
4202 const int rw
= rq_data_dir(rq
);
4203 const bool is_sync
= rq_is_sync(rq
);
4204 struct cfq_queue
*cfqq
;
4206 might_sleep_if(gfp_mask
& __GFP_WAIT
);
4208 spin_lock_irq(q
->queue_lock
);
4210 check_ioprio_changed(cic
, bio
);
4211 check_blkcg_changed(cic
, bio
);
4213 cfqq
= cic_to_cfqq(cic
, is_sync
);
4214 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
4215 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
4216 cic_set_cfqq(cic
, cfqq
, is_sync
);
4219 * If the queue was seeky for too long, break it apart.
4221 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
4222 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
4223 cfqq
= split_cfqq(cic
, cfqq
);
4229 * Check to see if this queue is scheduled to merge with
4230 * another, closely cooperating queue. The merging of
4231 * queues happens here as it must be done in process context.
4232 * The reference on new_cfqq was taken in merge_cfqqs.
4235 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
4238 cfqq
->allocated
[rw
]++;
4241 cfqg_get(cfqq
->cfqg
);
4242 rq
->elv
.priv
[0] = cfqq
;
4243 rq
->elv
.priv
[1] = cfqq
->cfqg
;
4244 spin_unlock_irq(q
->queue_lock
);
4248 static void cfq_kick_queue(struct work_struct
*work
)
4250 struct cfq_data
*cfqd
=
4251 container_of(work
, struct cfq_data
, unplug_work
);
4252 struct request_queue
*q
= cfqd
->queue
;
4254 spin_lock_irq(q
->queue_lock
);
4255 __blk_run_queue(cfqd
->queue
);
4256 spin_unlock_irq(q
->queue_lock
);
4260 * Timer running if the active_queue is currently idling inside its time slice
4262 static void cfq_idle_slice_timer(unsigned long data
)
4264 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
4265 struct cfq_queue
*cfqq
;
4266 unsigned long flags
;
4269 cfq_log(cfqd
, "idle timer fired");
4271 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
4273 cfqq
= cfqd
->active_queue
;
4278 * We saw a request before the queue expired, let it through
4280 if (cfq_cfqq_must_dispatch(cfqq
))
4286 if (cfq_slice_used(cfqq
))
4290 * only expire and reinvoke request handler, if there are
4291 * other queues with pending requests
4293 if (!cfqd
->busy_queues
)
4297 * not expired and it has a request pending, let it dispatch
4299 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
4303 * Queue depth flag is reset only when the idle didn't succeed
4305 cfq_clear_cfqq_deep(cfqq
);
4308 cfq_slice_expired(cfqd
, timed_out
);
4310 cfq_schedule_dispatch(cfqd
);
4312 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
4315 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
4317 del_timer_sync(&cfqd
->idle_slice_timer
);
4318 cancel_work_sync(&cfqd
->unplug_work
);
4321 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
4325 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
4326 if (cfqd
->async_cfqq
[0][i
])
4327 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
4328 if (cfqd
->async_cfqq
[1][i
])
4329 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
4332 if (cfqd
->async_idle_cfqq
)
4333 cfq_put_queue(cfqd
->async_idle_cfqq
);
4336 static void cfq_exit_queue(struct elevator_queue
*e
)
4338 struct cfq_data
*cfqd
= e
->elevator_data
;
4339 struct request_queue
*q
= cfqd
->queue
;
4341 cfq_shutdown_timer_wq(cfqd
);
4343 spin_lock_irq(q
->queue_lock
);
4345 if (cfqd
->active_queue
)
4346 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
4348 cfq_put_async_queues(cfqd
);
4350 spin_unlock_irq(q
->queue_lock
);
4352 cfq_shutdown_timer_wq(cfqd
);
4354 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4355 blkcg_deactivate_policy(q
, &blkcg_policy_cfq
);
4357 kfree(cfqd
->root_group
);
4362 static int cfq_init_queue(struct request_queue
*q
, struct elevator_type
*e
)
4364 struct cfq_data
*cfqd
;
4365 struct blkcg_gq
*blkg __maybe_unused
;
4367 struct elevator_queue
*eq
;
4369 eq
= elevator_alloc(q
, e
);
4373 cfqd
= kzalloc_node(sizeof(*cfqd
), GFP_KERNEL
, q
->node
);
4375 kobject_put(&eq
->kobj
);
4378 eq
->elevator_data
= cfqd
;
4381 spin_lock_irq(q
->queue_lock
);
4383 spin_unlock_irq(q
->queue_lock
);
4385 /* Init root service tree */
4386 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
4388 /* Init root group and prefer root group over other groups by default */
4389 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4390 ret
= blkcg_activate_policy(q
, &blkcg_policy_cfq
);
4394 cfqd
->root_group
= blkg_to_cfqg(q
->root_blkg
);
4397 cfqd
->root_group
= kzalloc_node(sizeof(*cfqd
->root_group
),
4398 GFP_KERNEL
, cfqd
->queue
->node
);
4399 if (!cfqd
->root_group
)
4402 cfq_init_cfqg_base(cfqd
->root_group
);
4404 cfqd
->root_group
->weight
= 2 * CFQ_WEIGHT_DEFAULT
;
4405 cfqd
->root_group
->leaf_weight
= 2 * CFQ_WEIGHT_DEFAULT
;
4408 * Not strictly needed (since RB_ROOT just clears the node and we
4409 * zeroed cfqd on alloc), but better be safe in case someone decides
4410 * to add magic to the rb code
4412 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
4413 cfqd
->prio_trees
[i
] = RB_ROOT
;
4416 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4417 * Grab a permanent reference to it, so that the normal code flow
4418 * will not attempt to free it. oom_cfqq is linked to root_group
4419 * but shouldn't hold a reference as it'll never be unlinked. Lose
4420 * the reference from linking right away.
4422 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
4423 cfqd
->oom_cfqq
.ref
++;
4425 spin_lock_irq(q
->queue_lock
);
4426 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, cfqd
->root_group
);
4427 cfqg_put(cfqd
->root_group
);
4428 spin_unlock_irq(q
->queue_lock
);
4430 init_timer(&cfqd
->idle_slice_timer
);
4431 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
4432 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
4434 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
4436 cfqd
->cfq_quantum
= cfq_quantum
;
4437 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
4438 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
4439 cfqd
->cfq_back_max
= cfq_back_max
;
4440 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
4441 cfqd
->cfq_slice
[0] = cfq_slice_async
;
4442 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
4443 cfqd
->cfq_target_latency
= cfq_target_latency
;
4444 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
4445 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
4446 cfqd
->cfq_group_idle
= cfq_group_idle
;
4447 cfqd
->cfq_latency
= 1;
4450 * we optimistically start assuming sync ops weren't delayed in last
4451 * second, in order to have larger depth for async operations.
4453 cfqd
->last_delayed_sync
= jiffies
- HZ
;
4458 kobject_put(&eq
->kobj
);
4463 * sysfs parts below -->
4466 cfq_var_show(unsigned int var
, char *page
)
4468 return sprintf(page
, "%u\n", var
);
4472 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4474 char *p
= (char *) page
;
4476 *var
= simple_strtoul(p
, &p
, 10);
4480 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4481 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4483 struct cfq_data *cfqd = e->elevator_data; \
4484 unsigned int __data = __VAR; \
4486 __data = jiffies_to_msecs(__data); \
4487 return cfq_var_show(__data, (page)); \
4489 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4490 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4491 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4492 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4493 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4494 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4495 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4496 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4497 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4498 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4499 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4500 SHOW_FUNCTION(cfq_target_latency_show
, cfqd
->cfq_target_latency
, 1);
4501 #undef SHOW_FUNCTION
4503 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4504 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4506 struct cfq_data *cfqd = e->elevator_data; \
4507 unsigned int __data; \
4508 int ret = cfq_var_store(&__data, (page), count); \
4509 if (__data < (MIN)) \
4511 else if (__data > (MAX)) \
4514 *(__PTR) = msecs_to_jiffies(__data); \
4516 *(__PTR) = __data; \
4519 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4520 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4522 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4524 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4525 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4527 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4528 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4529 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4530 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4531 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4533 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4534 STORE_FUNCTION(cfq_target_latency_store
, &cfqd
->cfq_target_latency
, 1, UINT_MAX
, 1);
4535 #undef STORE_FUNCTION
4537 #define CFQ_ATTR(name) \
4538 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4540 static struct elv_fs_entry cfq_attrs
[] = {
4542 CFQ_ATTR(fifo_expire_sync
),
4543 CFQ_ATTR(fifo_expire_async
),
4544 CFQ_ATTR(back_seek_max
),
4545 CFQ_ATTR(back_seek_penalty
),
4546 CFQ_ATTR(slice_sync
),
4547 CFQ_ATTR(slice_async
),
4548 CFQ_ATTR(slice_async_rq
),
4549 CFQ_ATTR(slice_idle
),
4550 CFQ_ATTR(group_idle
),
4551 CFQ_ATTR(low_latency
),
4552 CFQ_ATTR(target_latency
),
4556 static struct elevator_type iosched_cfq
= {
4558 .elevator_merge_fn
= cfq_merge
,
4559 .elevator_merged_fn
= cfq_merged_request
,
4560 .elevator_merge_req_fn
= cfq_merged_requests
,
4561 .elevator_allow_merge_fn
= cfq_allow_merge
,
4562 .elevator_bio_merged_fn
= cfq_bio_merged
,
4563 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4564 .elevator_add_req_fn
= cfq_insert_request
,
4565 .elevator_activate_req_fn
= cfq_activate_request
,
4566 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4567 .elevator_completed_req_fn
= cfq_completed_request
,
4568 .elevator_former_req_fn
= elv_rb_former_request
,
4569 .elevator_latter_req_fn
= elv_rb_latter_request
,
4570 .elevator_init_icq_fn
= cfq_init_icq
,
4571 .elevator_exit_icq_fn
= cfq_exit_icq
,
4572 .elevator_set_req_fn
= cfq_set_request
,
4573 .elevator_put_req_fn
= cfq_put_request
,
4574 .elevator_may_queue_fn
= cfq_may_queue
,
4575 .elevator_init_fn
= cfq_init_queue
,
4576 .elevator_exit_fn
= cfq_exit_queue
,
4578 .icq_size
= sizeof(struct cfq_io_cq
),
4579 .icq_align
= __alignof__(struct cfq_io_cq
),
4580 .elevator_attrs
= cfq_attrs
,
4581 .elevator_name
= "cfq",
4582 .elevator_owner
= THIS_MODULE
,
4585 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4586 static struct blkcg_policy blkcg_policy_cfq
= {
4587 .pd_size
= sizeof(struct cfq_group
),
4588 .cftypes
= cfq_blkcg_files
,
4590 .pd_init_fn
= cfq_pd_init
,
4591 .pd_offline_fn
= cfq_pd_offline
,
4592 .pd_reset_stats_fn
= cfq_pd_reset_stats
,
4596 static int __init
cfq_init(void)
4601 * could be 0 on HZ < 1000 setups
4603 if (!cfq_slice_async
)
4604 cfq_slice_async
= 1;
4605 if (!cfq_slice_idle
)
4608 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4609 if (!cfq_group_idle
)
4612 ret
= blkcg_policy_register(&blkcg_policy_cfq
);
4620 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
4624 ret
= elv_register(&iosched_cfq
);
4631 kmem_cache_destroy(cfq_pool
);
4633 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4634 blkcg_policy_unregister(&blkcg_policy_cfq
);
4639 static void __exit
cfq_exit(void)
4641 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4642 blkcg_policy_unregister(&blkcg_policy_cfq
);
4644 elv_unregister(&iosched_cfq
);
4645 kmem_cache_destroy(cfq_pool
);
4648 module_init(cfq_init
);
4649 module_exit(cfq_exit
);
4651 MODULE_AUTHOR("Jens Axboe");
4652 MODULE_LICENSE("GPL");
4653 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");