2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
18 #include "blk-cgroup.h"
20 static struct blkio_policy_type blkio_policy_cfq __maybe_unused
;
25 /* max queue in one round of service */
26 static const int cfq_quantum
= 8;
27 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
28 /* maximum backwards seek, in KiB */
29 static const int cfq_back_max
= 16 * 1024;
30 /* penalty of a backwards seek */
31 static const int cfq_back_penalty
= 2;
32 static const int cfq_slice_sync
= HZ
/ 10;
33 static int cfq_slice_async
= HZ
/ 25;
34 static const int cfq_slice_async_rq
= 2;
35 static int cfq_slice_idle
= HZ
/ 125;
36 static int cfq_group_idle
= HZ
/ 125;
37 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
38 static const int cfq_hist_divisor
= 4;
41 * offset from end of service tree
43 #define CFQ_IDLE_DELAY (HZ / 5)
46 * below this threshold, we consider thinktime immediate
48 #define CFQ_MIN_TT (2)
50 #define CFQ_SLICE_SCALE (5)
51 #define CFQ_HW_QUEUE_MIN (5)
52 #define CFQ_SERVICE_SHIFT 12
54 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
55 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
56 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
57 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
59 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
60 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
61 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
63 static struct kmem_cache
*cfq_pool
;
65 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
66 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
67 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69 #define sample_valid(samples) ((samples) > 80)
70 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73 unsigned long last_end_request
;
75 unsigned long ttime_total
;
76 unsigned long ttime_samples
;
77 unsigned long ttime_mean
;
81 * Most of our rbtree usage is for sorting with min extraction, so
82 * if we cache the leftmost node we don't have to walk down the tree
83 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
84 * move this into the elevator for the rq sorting as well.
90 unsigned total_weight
;
92 struct cfq_ttime ttime
;
94 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
95 .ttime = {.last_end_request = jiffies,},}
98 * Per process-grouping structure
101 /* reference count */
103 /* various state flags, see below */
105 /* parent cfq_data */
106 struct cfq_data
*cfqd
;
107 /* service_tree member */
108 struct rb_node rb_node
;
109 /* service_tree key */
110 unsigned long rb_key
;
111 /* prio tree member */
112 struct rb_node p_node
;
113 /* prio tree root we belong to, if any */
114 struct rb_root
*p_root
;
115 /* sorted list of pending requests */
116 struct rb_root sort_list
;
117 /* if fifo isn't expired, next request to serve */
118 struct request
*next_rq
;
119 /* requests queued in sort_list */
121 /* currently allocated requests */
123 /* fifo list of requests in sort_list */
124 struct list_head fifo
;
126 /* time when queue got scheduled in to dispatch first request. */
127 unsigned long dispatch_start
;
128 unsigned int allocated_slice
;
129 unsigned int slice_dispatch
;
130 /* time when first request from queue completed and slice started. */
131 unsigned long slice_start
;
132 unsigned long slice_end
;
135 /* pending priority requests */
137 /* number of requests that are on the dispatch list or inside driver */
140 /* io prio of this group */
141 unsigned short ioprio
, org_ioprio
;
142 unsigned short ioprio_class
;
147 sector_t last_request_pos
;
149 struct cfq_rb_root
*service_tree
;
150 struct cfq_queue
*new_cfqq
;
151 struct cfq_group
*cfqg
;
152 /* Number of sectors dispatched from queue in single dispatch round */
153 unsigned long nr_sectors
;
157 * First index in the service_trees.
158 * IDLE is handled separately, so it has negative index
168 * Second index in the service_trees.
172 SYNC_NOIDLE_WORKLOAD
= 1,
177 #ifdef CONFIG_CFQ_GROUP_IOSCHED
178 /* total bytes transferred */
179 struct blkg_rwstat service_bytes
;
180 /* total IOs serviced, post merge */
181 struct blkg_rwstat serviced
;
182 /* number of ios merged */
183 struct blkg_rwstat merged
;
184 /* total time spent on device in ns, may not be accurate w/ queueing */
185 struct blkg_rwstat service_time
;
186 /* total time spent waiting in scheduler queue in ns */
187 struct blkg_rwstat wait_time
;
188 /* number of IOs queued up */
189 struct blkg_rwstat queued
;
190 /* total sectors transferred */
191 struct blkg_stat sectors
;
192 /* total disk time and nr sectors dispatched by this group */
193 struct blkg_stat time
;
194 #ifdef CONFIG_DEBUG_BLK_CGROUP
195 /* time not charged to this cgroup */
196 struct blkg_stat unaccounted_time
;
197 /* sum of number of ios queued across all samples */
198 struct blkg_stat avg_queue_size_sum
;
199 /* count of samples taken for average */
200 struct blkg_stat avg_queue_size_samples
;
201 /* how many times this group has been removed from service tree */
202 struct blkg_stat dequeue
;
203 /* total time spent waiting for it to be assigned a timeslice. */
204 struct blkg_stat group_wait_time
;
205 /* time spent idling for this blkio_group */
206 struct blkg_stat idle_time
;
207 /* total time with empty current active q with other requests queued */
208 struct blkg_stat empty_time
;
209 /* fields after this shouldn't be cleared on stat reset */
210 uint64_t start_group_wait_time
;
211 uint64_t start_idle_time
;
212 uint64_t start_empty_time
;
214 #endif /* CONFIG_DEBUG_BLK_CGROUP */
215 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
218 /* This is per cgroup per device grouping structure */
220 /* group service_tree member */
221 struct rb_node rb_node
;
223 /* group service_tree key */
226 unsigned int new_weight
;
227 unsigned int dev_weight
;
229 /* number of cfqq currently on this group */
233 * Per group busy queues average. Useful for workload slice calc. We
234 * create the array for each prio class but at run time it is used
235 * only for RT and BE class and slot for IDLE class remains unused.
236 * This is primarily done to avoid confusion and a gcc warning.
238 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
240 * rr lists of queues with requests. We maintain service trees for
241 * RT and BE classes. These trees are subdivided in subclasses
242 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
243 * class there is no subclassification and all the cfq queues go on
244 * a single tree service_tree_idle.
245 * Counts are embedded in the cfq_rb_root
247 struct cfq_rb_root service_trees
[2][3];
248 struct cfq_rb_root service_tree_idle
;
250 unsigned long saved_workload_slice
;
251 enum wl_type_t saved_workload
;
252 enum wl_prio_t saved_serving_prio
;
254 /* number of requests that are on the dispatch list or inside driver */
256 struct cfq_ttime ttime
;
257 struct cfqg_stats stats
;
261 struct io_cq icq
; /* must be the first member */
262 struct cfq_queue
*cfqq
[2];
263 struct cfq_ttime ttime
;
264 int ioprio
; /* the current ioprio */
265 #ifdef CONFIG_CFQ_GROUP_IOSCHED
266 uint64_t blkcg_id
; /* the current blkcg ID */
271 * Per block device queue structure
274 struct request_queue
*queue
;
275 /* Root service tree for cfq_groups */
276 struct cfq_rb_root grp_service_tree
;
277 struct cfq_group
*root_group
;
280 * The priority currently being served
282 enum wl_prio_t serving_prio
;
283 enum wl_type_t serving_type
;
284 unsigned long workload_expires
;
285 struct cfq_group
*serving_group
;
288 * Each priority tree is sorted by next_request position. These
289 * trees are used when determining if two or more queues are
290 * interleaving requests (see cfq_close_cooperator).
292 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
294 unsigned int busy_queues
;
295 unsigned int busy_sync_queues
;
301 * queue-depth detection
307 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
308 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
311 int hw_tag_est_depth
;
312 unsigned int hw_tag_samples
;
315 * idle window management
317 struct timer_list idle_slice_timer
;
318 struct work_struct unplug_work
;
320 struct cfq_queue
*active_queue
;
321 struct cfq_io_cq
*active_cic
;
324 * async queue for each priority case
326 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
327 struct cfq_queue
*async_idle_cfqq
;
329 sector_t last_position
;
332 * tunables, see top of file
334 unsigned int cfq_quantum
;
335 unsigned int cfq_fifo_expire
[2];
336 unsigned int cfq_back_penalty
;
337 unsigned int cfq_back_max
;
338 unsigned int cfq_slice
[2];
339 unsigned int cfq_slice_async_rq
;
340 unsigned int cfq_slice_idle
;
341 unsigned int cfq_group_idle
;
342 unsigned int cfq_latency
;
345 * Fallback dummy cfqq for extreme OOM conditions
347 struct cfq_queue oom_cfqq
;
349 unsigned long last_delayed_sync
;
352 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
354 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
361 if (prio
== IDLE_WORKLOAD
)
362 return &cfqg
->service_tree_idle
;
364 return &cfqg
->service_trees
[prio
][type
];
367 enum cfqq_state_flags
{
368 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
369 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
370 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
371 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
372 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
373 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
374 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
375 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
376 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
377 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
378 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
379 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
380 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
383 #define CFQ_CFQQ_FNS(name) \
384 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
386 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
388 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
390 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
392 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
394 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
398 CFQ_CFQQ_FNS(wait_request
);
399 CFQ_CFQQ_FNS(must_dispatch
);
400 CFQ_CFQQ_FNS(must_alloc_slice
);
401 CFQ_CFQQ_FNS(fifo_expire
);
402 CFQ_CFQQ_FNS(idle_window
);
403 CFQ_CFQQ_FNS(prio_changed
);
404 CFQ_CFQQ_FNS(slice_new
);
407 CFQ_CFQQ_FNS(split_coop
);
409 CFQ_CFQQ_FNS(wait_busy
);
412 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
414 /* cfqg stats flags */
415 enum cfqg_stats_flags
{
416 CFQG_stats_waiting
= 0,
421 #define CFQG_FLAG_FNS(name) \
422 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
424 stats->flags |= (1 << CFQG_stats_##name); \
426 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
428 stats->flags &= ~(1 << CFQG_stats_##name); \
430 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
432 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
435 CFQG_FLAG_FNS(waiting)
436 CFQG_FLAG_FNS(idling
)
440 /* This should be called with the queue_lock held. */
441 static void cfqg_stats_update_group_wait_time(struct cfqg_stats
*stats
)
443 unsigned long long now
;
445 if (!cfqg_stats_waiting(stats
))
449 if (time_after64(now
, stats
->start_group_wait_time
))
450 blkg_stat_add(&stats
->group_wait_time
,
451 now
- stats
->start_group_wait_time
);
452 cfqg_stats_clear_waiting(stats
);
455 /* This should be called with the queue_lock held. */
456 static void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
,
457 struct cfq_group
*curr_cfqg
)
459 struct cfqg_stats
*stats
= &cfqg
->stats
;
461 if (cfqg_stats_waiting(stats
))
463 if (cfqg
== curr_cfqg
)
465 stats
->start_group_wait_time
= sched_clock();
466 cfqg_stats_mark_waiting(stats
);
469 /* This should be called with the queue_lock held. */
470 static void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
)
472 unsigned long long now
;
474 if (!cfqg_stats_empty(stats
))
478 if (time_after64(now
, stats
->start_empty_time
))
479 blkg_stat_add(&stats
->empty_time
,
480 now
- stats
->start_empty_time
);
481 cfqg_stats_clear_empty(stats
);
484 static void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
)
486 blkg_stat_add(&cfqg
->stats
.dequeue
, 1);
489 static void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
)
491 struct cfqg_stats
*stats
= &cfqg
->stats
;
493 if (blkg_rwstat_sum(&stats
->queued
))
497 * group is already marked empty. This can happen if cfqq got new
498 * request in parent group and moved to this group while being added
499 * to service tree. Just ignore the event and move on.
501 if (cfqg_stats_empty(stats
))
504 stats
->start_empty_time
= sched_clock();
505 cfqg_stats_mark_empty(stats
);
508 static void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
)
510 struct cfqg_stats
*stats
= &cfqg
->stats
;
512 if (cfqg_stats_idling(stats
)) {
513 unsigned long long now
= sched_clock();
515 if (time_after64(now
, stats
->start_idle_time
))
516 blkg_stat_add(&stats
->idle_time
,
517 now
- stats
->start_idle_time
);
518 cfqg_stats_clear_idling(stats
);
522 static void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
)
524 struct cfqg_stats
*stats
= &cfqg
->stats
;
526 BUG_ON(cfqg_stats_idling(stats
));
528 stats
->start_idle_time
= sched_clock();
529 cfqg_stats_mark_idling(stats
);
532 static void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
)
534 struct cfqg_stats
*stats
= &cfqg
->stats
;
536 blkg_stat_add(&stats
->avg_queue_size_sum
,
537 blkg_rwstat_sum(&stats
->queued
));
538 blkg_stat_add(&stats
->avg_queue_size_samples
, 1);
539 cfqg_stats_update_group_wait_time(stats
);
542 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
544 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
, struct cfq_group
*curr_cfqg
) { }
545 static inline void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
) { }
546 static inline void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
) { }
547 static inline void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
) { }
548 static inline void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
) { }
549 static inline void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
) { }
550 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
) { }
552 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
554 #ifdef CONFIG_CFQ_GROUP_IOSCHED
556 static inline struct cfq_group
*blkg_to_cfqg(struct blkio_group
*blkg
)
558 return blkg_to_pdata(blkg
, &blkio_policy_cfq
);
561 static inline struct blkio_group
*cfqg_to_blkg(struct cfq_group
*cfqg
)
563 return pdata_to_blkg(cfqg
);
566 static inline void cfqg_get(struct cfq_group
*cfqg
)
568 return blkg_get(cfqg_to_blkg(cfqg
));
571 static inline void cfqg_put(struct cfq_group
*cfqg
)
573 return blkg_put(cfqg_to_blkg(cfqg
));
576 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
577 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
578 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
579 blkg_path(cfqg_to_blkg((cfqq)->cfqg)), ##args)
581 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
582 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
583 blkg_path(cfqg_to_blkg((cfqg))), ##args) \
585 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
586 struct cfq_group
*curr_cfqg
, int rw
)
588 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, 1);
589 cfqg_stats_end_empty_time(&cfqg
->stats
);
590 cfqg_stats_set_start_group_wait_time(cfqg
, curr_cfqg
);
593 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
594 unsigned long time
, unsigned long unaccounted_time
)
596 blkg_stat_add(&cfqg
->stats
.time
, time
);
597 #ifdef CONFIG_DEBUG_BLK_CGROUP
598 blkg_stat_add(&cfqg
->stats
.unaccounted_time
, unaccounted_time
);
602 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
)
604 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, -1);
607 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
)
609 blkg_rwstat_add(&cfqg
->stats
.merged
, rw
, 1);
612 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
613 uint64_t bytes
, int rw
)
615 blkg_stat_add(&cfqg
->stats
.sectors
, bytes
>> 9);
616 blkg_rwstat_add(&cfqg
->stats
.serviced
, rw
, 1);
617 blkg_rwstat_add(&cfqg
->stats
.service_bytes
, rw
, bytes
);
620 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
621 uint64_t start_time
, uint64_t io_start_time
, int rw
)
623 struct cfqg_stats
*stats
= &cfqg
->stats
;
624 unsigned long long now
= sched_clock();
626 if (time_after64(now
, io_start_time
))
627 blkg_rwstat_add(&stats
->service_time
, rw
, now
- io_start_time
);
628 if (time_after64(io_start_time
, start_time
))
629 blkg_rwstat_add(&stats
->wait_time
, rw
,
630 io_start_time
- start_time
);
633 static void cfqg_stats_reset(struct blkio_group
*blkg
)
635 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
636 struct cfqg_stats
*stats
= &cfqg
->stats
;
638 /* queued stats shouldn't be cleared */
639 blkg_rwstat_reset(&stats
->service_bytes
);
640 blkg_rwstat_reset(&stats
->serviced
);
641 blkg_rwstat_reset(&stats
->merged
);
642 blkg_rwstat_reset(&stats
->service_time
);
643 blkg_rwstat_reset(&stats
->wait_time
);
644 blkg_stat_reset(&stats
->time
);
645 #ifdef CONFIG_DEBUG_BLK_CGROUP
646 blkg_stat_reset(&stats
->unaccounted_time
);
647 blkg_stat_reset(&stats
->avg_queue_size_sum
);
648 blkg_stat_reset(&stats
->avg_queue_size_samples
);
649 blkg_stat_reset(&stats
->dequeue
);
650 blkg_stat_reset(&stats
->group_wait_time
);
651 blkg_stat_reset(&stats
->idle_time
);
652 blkg_stat_reset(&stats
->empty_time
);
656 #else /* CONFIG_CFQ_GROUP_IOSCHED */
658 static inline struct cfq_group
*blkg_to_cfqg(struct blkio_group
*blkg
) { return NULL
; }
659 static inline struct blkio_group
*cfqg_to_blkg(struct cfq_group
*cfqg
) { return NULL
; }
660 static inline void cfqg_get(struct cfq_group
*cfqg
) { }
661 static inline void cfqg_put(struct cfq_group
*cfqg
) { }
663 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
664 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
665 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
667 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
668 struct cfq_group
*curr_cfqg
, int rw
) { }
669 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
670 unsigned long time
, unsigned long unaccounted_time
) { }
671 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
) { }
672 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
) { }
673 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
674 uint64_t bytes
, int rw
) { }
675 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
676 uint64_t start_time
, uint64_t io_start_time
, int rw
) { }
678 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
680 #define cfq_log(cfqd, fmt, args...) \
681 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
683 /* Traverses through cfq group service trees */
684 #define for_each_cfqg_st(cfqg, i, j, st) \
685 for (i = 0; i <= IDLE_WORKLOAD; i++) \
686 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
687 : &cfqg->service_tree_idle; \
688 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
689 (i == IDLE_WORKLOAD && j == 0); \
690 j++, st = i < IDLE_WORKLOAD ? \
691 &cfqg->service_trees[i][j]: NULL) \
693 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
694 struct cfq_ttime
*ttime
, bool group_idle
)
697 if (!sample_valid(ttime
->ttime_samples
))
700 slice
= cfqd
->cfq_group_idle
;
702 slice
= cfqd
->cfq_slice_idle
;
703 return ttime
->ttime_mean
> slice
;
706 static inline bool iops_mode(struct cfq_data
*cfqd
)
709 * If we are not idling on queues and it is a NCQ drive, parallel
710 * execution of requests is on and measuring time is not possible
711 * in most of the cases until and unless we drive shallower queue
712 * depths and that becomes a performance bottleneck. In such cases
713 * switch to start providing fairness in terms of number of IOs.
715 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
721 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
723 if (cfq_class_idle(cfqq
))
724 return IDLE_WORKLOAD
;
725 if (cfq_class_rt(cfqq
))
731 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
733 if (!cfq_cfqq_sync(cfqq
))
734 return ASYNC_WORKLOAD
;
735 if (!cfq_cfqq_idle_window(cfqq
))
736 return SYNC_NOIDLE_WORKLOAD
;
737 return SYNC_WORKLOAD
;
740 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
741 struct cfq_data
*cfqd
,
742 struct cfq_group
*cfqg
)
744 if (wl
== IDLE_WORKLOAD
)
745 return cfqg
->service_tree_idle
.count
;
747 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
748 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
749 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
752 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
753 struct cfq_group
*cfqg
)
755 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
756 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
759 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
760 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
,
761 struct cfq_io_cq
*cic
, struct bio
*bio
,
764 static inline struct cfq_io_cq
*icq_to_cic(struct io_cq
*icq
)
766 /* cic->icq is the first member, %NULL will convert to %NULL */
767 return container_of(icq
, struct cfq_io_cq
, icq
);
770 static inline struct cfq_io_cq
*cfq_cic_lookup(struct cfq_data
*cfqd
,
771 struct io_context
*ioc
)
774 return icq_to_cic(ioc_lookup_icq(ioc
, cfqd
->queue
));
778 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_cq
*cic
, bool is_sync
)
780 return cic
->cfqq
[is_sync
];
783 static inline void cic_set_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
,
786 cic
->cfqq
[is_sync
] = cfqq
;
789 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_cq
*cic
)
791 return cic
->icq
.q
->elevator
->elevator_data
;
795 * We regard a request as SYNC, if it's either a read or has the SYNC bit
796 * set (in which case it could also be direct WRITE).
798 static inline bool cfq_bio_sync(struct bio
*bio
)
800 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
804 * scheduler run of queue, if there are requests pending and no one in the
805 * driver that will restart queueing
807 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
809 if (cfqd
->busy_queues
) {
810 cfq_log(cfqd
, "schedule dispatch");
811 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
816 * Scale schedule slice based on io priority. Use the sync time slice only
817 * if a queue is marked sync and has sync io queued. A sync queue with async
818 * io only, should not get full sync slice length.
820 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
823 const int base_slice
= cfqd
->cfq_slice
[sync
];
825 WARN_ON(prio
>= IOPRIO_BE_NR
);
827 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
831 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
833 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
836 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
838 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
840 d
= d
* CFQ_WEIGHT_DEFAULT
;
841 do_div(d
, cfqg
->weight
);
845 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
847 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
849 min_vdisktime
= vdisktime
;
851 return min_vdisktime
;
854 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
856 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
858 min_vdisktime
= vdisktime
;
860 return min_vdisktime
;
863 static void update_min_vdisktime(struct cfq_rb_root
*st
)
865 struct cfq_group
*cfqg
;
868 cfqg
= rb_entry_cfqg(st
->left
);
869 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
875 * get averaged number of queues of RT/BE priority.
876 * average is updated, with a formula that gives more weight to higher numbers,
877 * to quickly follows sudden increases and decrease slowly
880 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
881 struct cfq_group
*cfqg
, bool rt
)
883 unsigned min_q
, max_q
;
884 unsigned mult
= cfq_hist_divisor
- 1;
885 unsigned round
= cfq_hist_divisor
/ 2;
886 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
888 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
889 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
890 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
892 return cfqg
->busy_queues_avg
[rt
];
895 static inline unsigned
896 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
898 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
900 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
903 static inline unsigned
904 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
906 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
907 if (cfqd
->cfq_latency
) {
909 * interested queues (we consider only the ones with the same
910 * priority class in the cfq group)
912 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
914 unsigned sync_slice
= cfqd
->cfq_slice
[1];
915 unsigned expect_latency
= sync_slice
* iq
;
916 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
918 if (expect_latency
> group_slice
) {
919 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
920 /* scale low_slice according to IO priority
921 * and sync vs async */
923 min(slice
, base_low_slice
* slice
/ sync_slice
);
924 /* the adapted slice value is scaled to fit all iqs
925 * into the target latency */
926 slice
= max(slice
* group_slice
/ expect_latency
,
934 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
936 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
938 cfqq
->slice_start
= jiffies
;
939 cfqq
->slice_end
= jiffies
+ slice
;
940 cfqq
->allocated_slice
= slice
;
941 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
945 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
946 * isn't valid until the first request from the dispatch is activated
947 * and the slice time set.
949 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
951 if (cfq_cfqq_slice_new(cfqq
))
953 if (time_before(jiffies
, cfqq
->slice_end
))
960 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
961 * We choose the request that is closest to the head right now. Distance
962 * behind the head is penalized and only allowed to a certain extent.
964 static struct request
*
965 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
967 sector_t s1
, s2
, d1
= 0, d2
= 0;
968 unsigned long back_max
;
969 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
970 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
971 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
973 if (rq1
== NULL
|| rq1
== rq2
)
978 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
979 return rq_is_sync(rq1
) ? rq1
: rq2
;
981 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
982 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
984 s1
= blk_rq_pos(rq1
);
985 s2
= blk_rq_pos(rq2
);
988 * by definition, 1KiB is 2 sectors
990 back_max
= cfqd
->cfq_back_max
* 2;
993 * Strict one way elevator _except_ in the case where we allow
994 * short backward seeks which are biased as twice the cost of a
995 * similar forward seek.
999 else if (s1
+ back_max
>= last
)
1000 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
1002 wrap
|= CFQ_RQ1_WRAP
;
1006 else if (s2
+ back_max
>= last
)
1007 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
1009 wrap
|= CFQ_RQ2_WRAP
;
1011 /* Found required data */
1014 * By doing switch() on the bit mask "wrap" we avoid having to
1015 * check two variables for all permutations: --> faster!
1018 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1034 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
1037 * Since both rqs are wrapped,
1038 * start with the one that's further behind head
1039 * (--> only *one* back seek required),
1040 * since back seek takes more time than forward.
1050 * The below is leftmost cache rbtree addon
1052 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
1054 /* Service tree is empty */
1059 root
->left
= rb_first(&root
->rb
);
1062 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
1067 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
1070 root
->left
= rb_first(&root
->rb
);
1073 return rb_entry_cfqg(root
->left
);
1078 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
1084 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
1086 if (root
->left
== n
)
1088 rb_erase_init(n
, &root
->rb
);
1093 * would be nice to take fifo expire time into account as well
1095 static struct request
*
1096 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1097 struct request
*last
)
1099 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
1100 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
1101 struct request
*next
= NULL
, *prev
= NULL
;
1103 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
1106 prev
= rb_entry_rq(rbprev
);
1109 next
= rb_entry_rq(rbnext
);
1111 rbnext
= rb_first(&cfqq
->sort_list
);
1112 if (rbnext
&& rbnext
!= &last
->rb_node
)
1113 next
= rb_entry_rq(rbnext
);
1116 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
1119 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
1120 struct cfq_queue
*cfqq
)
1123 * just an approximation, should be ok.
1125 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
1126 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
1130 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1132 return cfqg
->vdisktime
- st
->min_vdisktime
;
1136 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1138 struct rb_node
**node
= &st
->rb
.rb_node
;
1139 struct rb_node
*parent
= NULL
;
1140 struct cfq_group
*__cfqg
;
1141 s64 key
= cfqg_key(st
, cfqg
);
1144 while (*node
!= NULL
) {
1146 __cfqg
= rb_entry_cfqg(parent
);
1148 if (key
< cfqg_key(st
, __cfqg
))
1149 node
= &parent
->rb_left
;
1151 node
= &parent
->rb_right
;
1157 st
->left
= &cfqg
->rb_node
;
1159 rb_link_node(&cfqg
->rb_node
, parent
, node
);
1160 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
1164 cfq_update_group_weight(struct cfq_group
*cfqg
)
1166 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1167 if (cfqg
->new_weight
) {
1168 cfqg
->weight
= cfqg
->new_weight
;
1169 cfqg
->new_weight
= 0;
1174 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1176 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1178 cfq_update_group_weight(cfqg
);
1179 __cfq_group_service_tree_add(st
, cfqg
);
1180 st
->total_weight
+= cfqg
->weight
;
1184 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1186 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1187 struct cfq_group
*__cfqg
;
1191 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1195 * Currently put the group at the end. Later implement something
1196 * so that groups get lesser vtime based on their weights, so that
1197 * if group does not loose all if it was not continuously backlogged.
1199 n
= rb_last(&st
->rb
);
1201 __cfqg
= rb_entry_cfqg(n
);
1202 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
1204 cfqg
->vdisktime
= st
->min_vdisktime
;
1205 cfq_group_service_tree_add(st
, cfqg
);
1209 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1211 st
->total_weight
-= cfqg
->weight
;
1212 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1213 cfq_rb_erase(&cfqg
->rb_node
, st
);
1217 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1219 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1221 BUG_ON(cfqg
->nr_cfqq
< 1);
1224 /* If there are other cfq queues under this group, don't delete it */
1228 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
1229 cfq_group_service_tree_del(st
, cfqg
);
1230 cfqg
->saved_workload_slice
= 0;
1231 cfqg_stats_update_dequeue(cfqg
);
1234 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
1235 unsigned int *unaccounted_time
)
1237 unsigned int slice_used
;
1240 * Queue got expired before even a single request completed or
1241 * got expired immediately after first request completion.
1243 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
1245 * Also charge the seek time incurred to the group, otherwise
1246 * if there are mutiple queues in the group, each can dispatch
1247 * a single request on seeky media and cause lots of seek time
1248 * and group will never know it.
1250 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
1253 slice_used
= jiffies
- cfqq
->slice_start
;
1254 if (slice_used
> cfqq
->allocated_slice
) {
1255 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
1256 slice_used
= cfqq
->allocated_slice
;
1258 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
1259 *unaccounted_time
+= cfqq
->slice_start
-
1260 cfqq
->dispatch_start
;
1266 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
1267 struct cfq_queue
*cfqq
)
1269 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1270 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
1271 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
1272 - cfqg
->service_tree_idle
.count
;
1274 BUG_ON(nr_sync
< 0);
1275 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
1277 if (iops_mode(cfqd
))
1278 charge
= cfqq
->slice_dispatch
;
1279 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
1280 charge
= cfqq
->allocated_slice
;
1282 /* Can't update vdisktime while group is on service tree */
1283 cfq_group_service_tree_del(st
, cfqg
);
1284 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
1285 /* If a new weight was requested, update now, off tree */
1286 cfq_group_service_tree_add(st
, cfqg
);
1288 /* This group is being expired. Save the context */
1289 if (time_after(cfqd
->workload_expires
, jiffies
)) {
1290 cfqg
->saved_workload_slice
= cfqd
->workload_expires
1292 cfqg
->saved_workload
= cfqd
->serving_type
;
1293 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
1295 cfqg
->saved_workload_slice
= 0;
1297 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1299 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1300 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1301 used_sl
, cfqq
->slice_dispatch
, charge
,
1302 iops_mode(cfqd
), cfqq
->nr_sectors
);
1303 cfqg_stats_update_timeslice_used(cfqg
, used_sl
, unaccounted_sl
);
1304 cfqg_stats_set_start_empty_time(cfqg
);
1308 * cfq_init_cfqg_base - initialize base part of a cfq_group
1309 * @cfqg: cfq_group to initialize
1311 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1312 * is enabled or not.
1314 static void cfq_init_cfqg_base(struct cfq_group
*cfqg
)
1316 struct cfq_rb_root
*st
;
1319 for_each_cfqg_st(cfqg
, i
, j
, st
)
1321 RB_CLEAR_NODE(&cfqg
->rb_node
);
1323 cfqg
->ttime
.last_end_request
= jiffies
;
1326 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1327 static void cfq_init_blkio_group(struct blkio_group
*blkg
)
1329 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1331 cfq_init_cfqg_base(cfqg
);
1332 cfqg
->weight
= blkg
->blkcg
->cfq_weight
;
1336 * Search for the cfq group current task belongs to. request_queue lock must
1339 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1340 struct blkio_cgroup
*blkcg
)
1342 struct request_queue
*q
= cfqd
->queue
;
1343 struct cfq_group
*cfqg
= NULL
;
1345 /* avoid lookup for the common case where there's no blkio cgroup */
1346 if (blkcg
== &blkio_root_cgroup
) {
1347 cfqg
= cfqd
->root_group
;
1349 struct blkio_group
*blkg
;
1351 blkg
= blkg_lookup_create(blkcg
, q
, false);
1353 cfqg
= blkg_to_cfqg(blkg
);
1359 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1361 /* Currently, all async queues are mapped to root group */
1362 if (!cfq_cfqq_sync(cfqq
))
1363 cfqg
= cfqq
->cfqd
->root_group
;
1366 /* cfqq reference on cfqg */
1370 static u64
cfqg_prfill_weight_device(struct seq_file
*sf
, void *pdata
, int off
)
1372 struct cfq_group
*cfqg
= pdata
;
1374 if (!cfqg
->dev_weight
)
1376 return __blkg_prfill_u64(sf
, pdata
, cfqg
->dev_weight
);
1379 static int cfqg_print_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1380 struct seq_file
*sf
)
1382 blkcg_print_blkgs(sf
, cgroup_to_blkio_cgroup(cgrp
),
1383 cfqg_prfill_weight_device
, &blkio_policy_cfq
, 0,
1388 static int cfq_print_weight(struct cgroup
*cgrp
, struct cftype
*cft
,
1389 struct seq_file
*sf
)
1391 seq_printf(sf
, "%u\n", cgroup_to_blkio_cgroup(cgrp
)->cfq_weight
);
1395 static int cfqg_set_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1398 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1399 struct blkg_conf_ctx ctx
;
1400 struct cfq_group
*cfqg
;
1403 ret
= blkg_conf_prep(blkcg
, buf
, &ctx
);
1408 cfqg
= blkg_to_cfqg(ctx
.blkg
);
1409 if (cfqg
&& (!ctx
.v
|| (ctx
.v
>= CFQ_WEIGHT_MIN
&&
1410 ctx
.v
<= CFQ_WEIGHT_MAX
))) {
1411 cfqg
->dev_weight
= ctx
.v
;
1412 cfqg
->new_weight
= cfqg
->dev_weight
?: blkcg
->cfq_weight
;
1416 blkg_conf_finish(&ctx
);
1420 static int cfq_set_weight(struct cgroup
*cgrp
, struct cftype
*cft
, u64 val
)
1422 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1423 struct blkio_group
*blkg
;
1424 struct hlist_node
*n
;
1426 if (val
< CFQ_WEIGHT_MIN
|| val
> CFQ_WEIGHT_MAX
)
1429 spin_lock_irq(&blkcg
->lock
);
1430 blkcg
->cfq_weight
= (unsigned int)val
;
1432 hlist_for_each_entry(blkg
, n
, &blkcg
->blkg_list
, blkcg_node
) {
1433 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1435 if (cfqg
&& !cfqg
->dev_weight
)
1436 cfqg
->new_weight
= blkcg
->cfq_weight
;
1439 spin_unlock_irq(&blkcg
->lock
);
1443 static int cfqg_print_stat(struct cgroup
*cgrp
, struct cftype
*cft
,
1444 struct seq_file
*sf
)
1446 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1448 blkcg_print_blkgs(sf
, blkcg
, blkg_prfill_stat
, &blkio_policy_cfq
,
1449 cft
->private, false);
1453 static int cfqg_print_rwstat(struct cgroup
*cgrp
, struct cftype
*cft
,
1454 struct seq_file
*sf
)
1456 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1458 blkcg_print_blkgs(sf
, blkcg
, blkg_prfill_rwstat
, &blkio_policy_cfq
,
1459 cft
->private, true);
1463 #ifdef CONFIG_DEBUG_BLK_CGROUP
1464 static u64
cfqg_prfill_avg_queue_size(struct seq_file
*sf
, void *pdata
, int off
)
1466 struct cfq_group
*cfqg
= pdata
;
1467 u64 samples
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_samples
);
1471 v
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_sum
);
1474 __blkg_prfill_u64(sf
, pdata
, v
);
1478 /* print avg_queue_size */
1479 static int cfqg_print_avg_queue_size(struct cgroup
*cgrp
, struct cftype
*cft
,
1480 struct seq_file
*sf
)
1482 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1484 blkcg_print_blkgs(sf
, blkcg
, cfqg_prfill_avg_queue_size
,
1485 &blkio_policy_cfq
, 0, false);
1488 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1490 static struct cftype cfq_blkcg_files
[] = {
1492 .name
= "weight_device",
1493 .read_seq_string
= cfqg_print_weight_device
,
1494 .write_string
= cfqg_set_weight_device
,
1495 .max_write_len
= 256,
1499 .read_seq_string
= cfq_print_weight
,
1500 .write_u64
= cfq_set_weight
,
1504 .private = offsetof(struct cfq_group
, stats
.time
),
1505 .read_seq_string
= cfqg_print_stat
,
1509 .private = offsetof(struct cfq_group
, stats
.sectors
),
1510 .read_seq_string
= cfqg_print_stat
,
1513 .name
= "io_service_bytes",
1514 .private = offsetof(struct cfq_group
, stats
.service_bytes
),
1515 .read_seq_string
= cfqg_print_rwstat
,
1518 .name
= "io_serviced",
1519 .private = offsetof(struct cfq_group
, stats
.serviced
),
1520 .read_seq_string
= cfqg_print_rwstat
,
1523 .name
= "io_service_time",
1524 .private = offsetof(struct cfq_group
, stats
.service_time
),
1525 .read_seq_string
= cfqg_print_rwstat
,
1528 .name
= "io_wait_time",
1529 .private = offsetof(struct cfq_group
, stats
.wait_time
),
1530 .read_seq_string
= cfqg_print_rwstat
,
1533 .name
= "io_merged",
1534 .private = offsetof(struct cfq_group
, stats
.merged
),
1535 .read_seq_string
= cfqg_print_rwstat
,
1538 .name
= "io_queued",
1539 .private = offsetof(struct cfq_group
, stats
.queued
),
1540 .read_seq_string
= cfqg_print_rwstat
,
1542 #ifdef CONFIG_DEBUG_BLK_CGROUP
1544 .name
= "avg_queue_size",
1545 .read_seq_string
= cfqg_print_avg_queue_size
,
1548 .name
= "group_wait_time",
1549 .private = offsetof(struct cfq_group
, stats
.group_wait_time
),
1550 .read_seq_string
= cfqg_print_stat
,
1553 .name
= "idle_time",
1554 .private = offsetof(struct cfq_group
, stats
.idle_time
),
1555 .read_seq_string
= cfqg_print_stat
,
1558 .name
= "empty_time",
1559 .private = offsetof(struct cfq_group
, stats
.empty_time
),
1560 .read_seq_string
= cfqg_print_stat
,
1564 .private = offsetof(struct cfq_group
, stats
.dequeue
),
1565 .read_seq_string
= cfqg_print_stat
,
1568 .name
= "unaccounted_time",
1569 .private = offsetof(struct cfq_group
, stats
.unaccounted_time
),
1570 .read_seq_string
= cfqg_print_stat
,
1572 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1575 #else /* GROUP_IOSCHED */
1576 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1577 struct blkio_cgroup
*blkcg
)
1579 return cfqd
->root_group
;
1583 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1587 #endif /* GROUP_IOSCHED */
1590 * The cfqd->service_trees holds all pending cfq_queue's that have
1591 * requests waiting to be processed. It is sorted in the order that
1592 * we will service the queues.
1594 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1597 struct rb_node
**p
, *parent
;
1598 struct cfq_queue
*__cfqq
;
1599 unsigned long rb_key
;
1600 struct cfq_rb_root
*service_tree
;
1604 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1606 if (cfq_class_idle(cfqq
)) {
1607 rb_key
= CFQ_IDLE_DELAY
;
1608 parent
= rb_last(&service_tree
->rb
);
1609 if (parent
&& parent
!= &cfqq
->rb_node
) {
1610 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1611 rb_key
+= __cfqq
->rb_key
;
1614 } else if (!add_front
) {
1616 * Get our rb key offset. Subtract any residual slice
1617 * value carried from last service. A negative resid
1618 * count indicates slice overrun, and this should position
1619 * the next service time further away in the tree.
1621 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1622 rb_key
-= cfqq
->slice_resid
;
1623 cfqq
->slice_resid
= 0;
1626 __cfqq
= cfq_rb_first(service_tree
);
1627 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1630 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1633 * same position, nothing more to do
1635 if (rb_key
== cfqq
->rb_key
&&
1636 cfqq
->service_tree
== service_tree
)
1639 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1640 cfqq
->service_tree
= NULL
;
1645 cfqq
->service_tree
= service_tree
;
1646 p
= &service_tree
->rb
.rb_node
;
1651 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1654 * sort by key, that represents service time.
1656 if (time_before(rb_key
, __cfqq
->rb_key
))
1659 n
= &(*p
)->rb_right
;
1667 service_tree
->left
= &cfqq
->rb_node
;
1669 cfqq
->rb_key
= rb_key
;
1670 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1671 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1672 service_tree
->count
++;
1673 if (add_front
|| !new_cfqq
)
1675 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1678 static struct cfq_queue
*
1679 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1680 sector_t sector
, struct rb_node
**ret_parent
,
1681 struct rb_node
***rb_link
)
1683 struct rb_node
**p
, *parent
;
1684 struct cfq_queue
*cfqq
= NULL
;
1692 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1695 * Sort strictly based on sector. Smallest to the left,
1696 * largest to the right.
1698 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1699 n
= &(*p
)->rb_right
;
1700 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1708 *ret_parent
= parent
;
1714 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1716 struct rb_node
**p
, *parent
;
1717 struct cfq_queue
*__cfqq
;
1720 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1721 cfqq
->p_root
= NULL
;
1724 if (cfq_class_idle(cfqq
))
1729 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1730 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1731 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1733 rb_link_node(&cfqq
->p_node
, parent
, p
);
1734 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1736 cfqq
->p_root
= NULL
;
1740 * Update cfqq's position in the service tree.
1742 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1745 * Resorting requires the cfqq to be on the RR list already.
1747 if (cfq_cfqq_on_rr(cfqq
)) {
1748 cfq_service_tree_add(cfqd
, cfqq
, 0);
1749 cfq_prio_tree_add(cfqd
, cfqq
);
1754 * add to busy list of queues for service, trying to be fair in ordering
1755 * the pending list according to last request service
1757 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1759 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1760 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1761 cfq_mark_cfqq_on_rr(cfqq
);
1762 cfqd
->busy_queues
++;
1763 if (cfq_cfqq_sync(cfqq
))
1764 cfqd
->busy_sync_queues
++;
1766 cfq_resort_rr_list(cfqd
, cfqq
);
1770 * Called when the cfqq no longer has requests pending, remove it from
1773 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1775 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1776 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1777 cfq_clear_cfqq_on_rr(cfqq
);
1779 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1780 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1781 cfqq
->service_tree
= NULL
;
1784 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1785 cfqq
->p_root
= NULL
;
1788 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1789 BUG_ON(!cfqd
->busy_queues
);
1790 cfqd
->busy_queues
--;
1791 if (cfq_cfqq_sync(cfqq
))
1792 cfqd
->busy_sync_queues
--;
1796 * rb tree support functions
1798 static void cfq_del_rq_rb(struct request
*rq
)
1800 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1801 const int sync
= rq_is_sync(rq
);
1803 BUG_ON(!cfqq
->queued
[sync
]);
1804 cfqq
->queued
[sync
]--;
1806 elv_rb_del(&cfqq
->sort_list
, rq
);
1808 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1810 * Queue will be deleted from service tree when we actually
1811 * expire it later. Right now just remove it from prio tree
1815 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1816 cfqq
->p_root
= NULL
;
1821 static void cfq_add_rq_rb(struct request
*rq
)
1823 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1824 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1825 struct request
*prev
;
1827 cfqq
->queued
[rq_is_sync(rq
)]++;
1829 elv_rb_add(&cfqq
->sort_list
, rq
);
1831 if (!cfq_cfqq_on_rr(cfqq
))
1832 cfq_add_cfqq_rr(cfqd
, cfqq
);
1835 * check if this request is a better next-serve candidate
1837 prev
= cfqq
->next_rq
;
1838 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1841 * adjust priority tree position, if ->next_rq changes
1843 if (prev
!= cfqq
->next_rq
)
1844 cfq_prio_tree_add(cfqd
, cfqq
);
1846 BUG_ON(!cfqq
->next_rq
);
1849 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1851 elv_rb_del(&cfqq
->sort_list
, rq
);
1852 cfqq
->queued
[rq_is_sync(rq
)]--;
1853 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1855 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqq
->cfqd
->serving_group
,
1859 static struct request
*
1860 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1862 struct task_struct
*tsk
= current
;
1863 struct cfq_io_cq
*cic
;
1864 struct cfq_queue
*cfqq
;
1866 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1870 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1872 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1874 return elv_rb_find(&cfqq
->sort_list
, sector
);
1880 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1882 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1884 cfqd
->rq_in_driver
++;
1885 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1886 cfqd
->rq_in_driver
);
1888 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1891 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1893 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1895 WARN_ON(!cfqd
->rq_in_driver
);
1896 cfqd
->rq_in_driver
--;
1897 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1898 cfqd
->rq_in_driver
);
1901 static void cfq_remove_request(struct request
*rq
)
1903 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1905 if (cfqq
->next_rq
== rq
)
1906 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1908 list_del_init(&rq
->queuelist
);
1911 cfqq
->cfqd
->rq_queued
--;
1912 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1913 if (rq
->cmd_flags
& REQ_PRIO
) {
1914 WARN_ON(!cfqq
->prio_pending
);
1915 cfqq
->prio_pending
--;
1919 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1922 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1923 struct request
*__rq
;
1925 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1926 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1928 return ELEVATOR_FRONT_MERGE
;
1931 return ELEVATOR_NO_MERGE
;
1934 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1937 if (type
== ELEVATOR_FRONT_MERGE
) {
1938 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1940 cfq_reposition_rq_rb(cfqq
, req
);
1944 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1947 cfqg_stats_update_io_merged(RQ_CFQG(req
), bio
->bi_rw
);
1951 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1952 struct request
*next
)
1954 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1955 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1958 * reposition in fifo if next is older than rq
1960 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1961 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1962 list_move(&rq
->queuelist
, &next
->queuelist
);
1963 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1966 if (cfqq
->next_rq
== next
)
1968 cfq_remove_request(next
);
1969 cfqg_stats_update_io_merged(RQ_CFQG(rq
), next
->cmd_flags
);
1971 cfqq
= RQ_CFQQ(next
);
1973 * all requests of this queue are merged to other queues, delete it
1974 * from the service tree. If it's the active_queue,
1975 * cfq_dispatch_requests() will choose to expire it or do idle
1977 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
) &&
1978 cfqq
!= cfqd
->active_queue
)
1979 cfq_del_cfqq_rr(cfqd
, cfqq
);
1982 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1985 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1986 struct cfq_io_cq
*cic
;
1987 struct cfq_queue
*cfqq
;
1990 * Disallow merge of a sync bio into an async request.
1992 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1996 * Lookup the cfqq that this bio will be queued with and allow
1997 * merge only if rq is queued there.
1999 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
2003 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
2004 return cfqq
== RQ_CFQQ(rq
);
2007 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2009 del_timer(&cfqd
->idle_slice_timer
);
2010 cfqg_stats_update_idle_time(cfqq
->cfqg
);
2013 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
2014 struct cfq_queue
*cfqq
)
2017 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
2018 cfqd
->serving_prio
, cfqd
->serving_type
);
2019 cfqg_stats_update_avg_queue_size(cfqq
->cfqg
);
2020 cfqq
->slice_start
= 0;
2021 cfqq
->dispatch_start
= jiffies
;
2022 cfqq
->allocated_slice
= 0;
2023 cfqq
->slice_end
= 0;
2024 cfqq
->slice_dispatch
= 0;
2025 cfqq
->nr_sectors
= 0;
2027 cfq_clear_cfqq_wait_request(cfqq
);
2028 cfq_clear_cfqq_must_dispatch(cfqq
);
2029 cfq_clear_cfqq_must_alloc_slice(cfqq
);
2030 cfq_clear_cfqq_fifo_expire(cfqq
);
2031 cfq_mark_cfqq_slice_new(cfqq
);
2033 cfq_del_timer(cfqd
, cfqq
);
2036 cfqd
->active_queue
= cfqq
;
2040 * current cfqq expired its slice (or was too idle), select new one
2043 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2046 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
2048 if (cfq_cfqq_wait_request(cfqq
))
2049 cfq_del_timer(cfqd
, cfqq
);
2051 cfq_clear_cfqq_wait_request(cfqq
);
2052 cfq_clear_cfqq_wait_busy(cfqq
);
2055 * If this cfqq is shared between multiple processes, check to
2056 * make sure that those processes are still issuing I/Os within
2057 * the mean seek distance. If not, it may be time to break the
2058 * queues apart again.
2060 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
2061 cfq_mark_cfqq_split_coop(cfqq
);
2064 * store what was left of this slice, if the queue idled/timed out
2067 if (cfq_cfqq_slice_new(cfqq
))
2068 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
2070 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
2071 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
2074 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
2076 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
2077 cfq_del_cfqq_rr(cfqd
, cfqq
);
2079 cfq_resort_rr_list(cfqd
, cfqq
);
2081 if (cfqq
== cfqd
->active_queue
)
2082 cfqd
->active_queue
= NULL
;
2084 if (cfqd
->active_cic
) {
2085 put_io_context(cfqd
->active_cic
->icq
.ioc
);
2086 cfqd
->active_cic
= NULL
;
2090 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
2092 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2095 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
2099 * Get next queue for service. Unless we have a queue preemption,
2100 * we'll simply select the first cfqq in the service tree.
2102 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
2104 struct cfq_rb_root
*service_tree
=
2105 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
2106 cfqd
->serving_type
);
2108 if (!cfqd
->rq_queued
)
2111 /* There is nothing to dispatch */
2114 if (RB_EMPTY_ROOT(&service_tree
->rb
))
2116 return cfq_rb_first(service_tree
);
2119 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
2121 struct cfq_group
*cfqg
;
2122 struct cfq_queue
*cfqq
;
2124 struct cfq_rb_root
*st
;
2126 if (!cfqd
->rq_queued
)
2129 cfqg
= cfq_get_next_cfqg(cfqd
);
2133 for_each_cfqg_st(cfqg
, i
, j
, st
)
2134 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
2140 * Get and set a new active queue for service.
2142 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
2143 struct cfq_queue
*cfqq
)
2146 cfqq
= cfq_get_next_queue(cfqd
);
2148 __cfq_set_active_queue(cfqd
, cfqq
);
2152 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
2155 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
2156 return blk_rq_pos(rq
) - cfqd
->last_position
;
2158 return cfqd
->last_position
- blk_rq_pos(rq
);
2161 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2164 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
2167 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
2168 struct cfq_queue
*cur_cfqq
)
2170 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
2171 struct rb_node
*parent
, *node
;
2172 struct cfq_queue
*__cfqq
;
2173 sector_t sector
= cfqd
->last_position
;
2175 if (RB_EMPTY_ROOT(root
))
2179 * First, if we find a request starting at the end of the last
2180 * request, choose it.
2182 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
2187 * If the exact sector wasn't found, the parent of the NULL leaf
2188 * will contain the closest sector.
2190 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
2191 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2194 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
2195 node
= rb_next(&__cfqq
->p_node
);
2197 node
= rb_prev(&__cfqq
->p_node
);
2201 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
2202 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2210 * cur_cfqq - passed in so that we don't decide that the current queue is
2211 * closely cooperating with itself.
2213 * So, basically we're assuming that that cur_cfqq has dispatched at least
2214 * one request, and that cfqd->last_position reflects a position on the disk
2215 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2218 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
2219 struct cfq_queue
*cur_cfqq
)
2221 struct cfq_queue
*cfqq
;
2223 if (cfq_class_idle(cur_cfqq
))
2225 if (!cfq_cfqq_sync(cur_cfqq
))
2227 if (CFQQ_SEEKY(cur_cfqq
))
2231 * Don't search priority tree if it's the only queue in the group.
2233 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
2237 * We should notice if some of the queues are cooperating, eg
2238 * working closely on the same area of the disk. In that case,
2239 * we can group them together and don't waste time idling.
2241 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
2245 /* If new queue belongs to different cfq_group, don't choose it */
2246 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
2250 * It only makes sense to merge sync queues.
2252 if (!cfq_cfqq_sync(cfqq
))
2254 if (CFQQ_SEEKY(cfqq
))
2258 * Do not merge queues of different priority classes
2260 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
2267 * Determine whether we should enforce idle window for this queue.
2270 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2272 enum wl_prio_t prio
= cfqq_prio(cfqq
);
2273 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
2275 BUG_ON(!service_tree
);
2276 BUG_ON(!service_tree
->count
);
2278 if (!cfqd
->cfq_slice_idle
)
2281 /* We never do for idle class queues. */
2282 if (prio
== IDLE_WORKLOAD
)
2285 /* We do for queues that were marked with idle window flag. */
2286 if (cfq_cfqq_idle_window(cfqq
) &&
2287 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
2291 * Otherwise, we do only if they are the last ones
2292 * in their service tree.
2294 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
2295 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
2297 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
2298 service_tree
->count
);
2302 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2304 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2305 struct cfq_io_cq
*cic
;
2306 unsigned long sl
, group_idle
= 0;
2309 * SSD device without seek penalty, disable idling. But only do so
2310 * for devices that support queuing, otherwise we still have a problem
2311 * with sync vs async workloads.
2313 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2316 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2317 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2320 * idle is disabled, either manually or by past process history
2322 if (!cfq_should_idle(cfqd
, cfqq
)) {
2323 /* no queue idling. Check for group idling */
2324 if (cfqd
->cfq_group_idle
)
2325 group_idle
= cfqd
->cfq_group_idle
;
2331 * still active requests from this queue, don't idle
2333 if (cfqq
->dispatched
)
2337 * task has exited, don't wait
2339 cic
= cfqd
->active_cic
;
2340 if (!cic
|| !atomic_read(&cic
->icq
.ioc
->active_ref
))
2344 * If our average think time is larger than the remaining time
2345 * slice, then don't idle. This avoids overrunning the allotted
2348 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2349 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2350 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2351 cic
->ttime
.ttime_mean
);
2355 /* There are other queues in the group, don't do group idle */
2356 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2359 cfq_mark_cfqq_wait_request(cfqq
);
2362 sl
= cfqd
->cfq_group_idle
;
2364 sl
= cfqd
->cfq_slice_idle
;
2366 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2367 cfqg_stats_set_start_idle_time(cfqq
->cfqg
);
2368 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2369 group_idle
? 1 : 0);
2373 * Move request from internal lists to the request queue dispatch list.
2375 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2377 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2378 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2380 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2382 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2383 cfq_remove_request(rq
);
2385 (RQ_CFQG(rq
))->dispatched
++;
2386 elv_dispatch_sort(q
, rq
);
2388 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2389 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2390 cfqg_stats_update_dispatch(cfqq
->cfqg
, blk_rq_bytes(rq
), rq
->cmd_flags
);
2394 * return expired entry, or NULL to just start from scratch in rbtree
2396 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2398 struct request
*rq
= NULL
;
2400 if (cfq_cfqq_fifo_expire(cfqq
))
2403 cfq_mark_cfqq_fifo_expire(cfqq
);
2405 if (list_empty(&cfqq
->fifo
))
2408 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2409 if (time_before(jiffies
, rq_fifo_time(rq
)))
2412 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2417 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2419 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2421 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2423 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2427 * Must be called with the queue_lock held.
2429 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2431 int process_refs
, io_refs
;
2433 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2434 process_refs
= cfqq
->ref
- io_refs
;
2435 BUG_ON(process_refs
< 0);
2436 return process_refs
;
2439 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2441 int process_refs
, new_process_refs
;
2442 struct cfq_queue
*__cfqq
;
2445 * If there are no process references on the new_cfqq, then it is
2446 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2447 * chain may have dropped their last reference (not just their
2448 * last process reference).
2450 if (!cfqq_process_refs(new_cfqq
))
2453 /* Avoid a circular list and skip interim queue merges */
2454 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2460 process_refs
= cfqq_process_refs(cfqq
);
2461 new_process_refs
= cfqq_process_refs(new_cfqq
);
2463 * If the process for the cfqq has gone away, there is no
2464 * sense in merging the queues.
2466 if (process_refs
== 0 || new_process_refs
== 0)
2470 * Merge in the direction of the lesser amount of work.
2472 if (new_process_refs
>= process_refs
) {
2473 cfqq
->new_cfqq
= new_cfqq
;
2474 new_cfqq
->ref
+= process_refs
;
2476 new_cfqq
->new_cfqq
= cfqq
;
2477 cfqq
->ref
+= new_process_refs
;
2481 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2482 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2484 struct cfq_queue
*queue
;
2486 bool key_valid
= false;
2487 unsigned long lowest_key
= 0;
2488 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2490 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2491 /* select the one with lowest rb_key */
2492 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2494 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2495 lowest_key
= queue
->rb_key
;
2504 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2508 struct cfq_rb_root
*st
;
2509 unsigned group_slice
;
2510 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2512 /* Choose next priority. RT > BE > IDLE */
2513 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2514 cfqd
->serving_prio
= RT_WORKLOAD
;
2515 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2516 cfqd
->serving_prio
= BE_WORKLOAD
;
2518 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2519 cfqd
->workload_expires
= jiffies
+ 1;
2523 if (original_prio
!= cfqd
->serving_prio
)
2527 * For RT and BE, we have to choose also the type
2528 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2531 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2535 * check workload expiration, and that we still have other queues ready
2537 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2541 /* otherwise select new workload type */
2542 cfqd
->serving_type
=
2543 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2544 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2548 * the workload slice is computed as a fraction of target latency
2549 * proportional to the number of queues in that workload, over
2550 * all the queues in the same priority class
2552 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2554 slice
= group_slice
* count
/
2555 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2556 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2558 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2562 * Async queues are currently system wide. Just taking
2563 * proportion of queues with-in same group will lead to higher
2564 * async ratio system wide as generally root group is going
2565 * to have higher weight. A more accurate thing would be to
2566 * calculate system wide asnc/sync ratio.
2568 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2569 tmp
= tmp
/cfqd
->busy_queues
;
2570 slice
= min_t(unsigned, slice
, tmp
);
2572 /* async workload slice is scaled down according to
2573 * the sync/async slice ratio. */
2574 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2576 /* sync workload slice is at least 2 * cfq_slice_idle */
2577 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2579 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2580 cfq_log(cfqd
, "workload slice:%d", slice
);
2581 cfqd
->workload_expires
= jiffies
+ slice
;
2584 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2586 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2587 struct cfq_group
*cfqg
;
2589 if (RB_EMPTY_ROOT(&st
->rb
))
2591 cfqg
= cfq_rb_first_group(st
);
2592 update_min_vdisktime(st
);
2596 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2598 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2600 cfqd
->serving_group
= cfqg
;
2602 /* Restore the workload type data */
2603 if (cfqg
->saved_workload_slice
) {
2604 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2605 cfqd
->serving_type
= cfqg
->saved_workload
;
2606 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2608 cfqd
->workload_expires
= jiffies
- 1;
2610 choose_service_tree(cfqd
, cfqg
);
2614 * Select a queue for service. If we have a current active queue,
2615 * check whether to continue servicing it, or retrieve and set a new one.
2617 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2619 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2621 cfqq
= cfqd
->active_queue
;
2625 if (!cfqd
->rq_queued
)
2629 * We were waiting for group to get backlogged. Expire the queue
2631 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2635 * The active queue has run out of time, expire it and select new.
2637 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2639 * If slice had not expired at the completion of last request
2640 * we might not have turned on wait_busy flag. Don't expire
2641 * the queue yet. Allow the group to get backlogged.
2643 * The very fact that we have used the slice, that means we
2644 * have been idling all along on this queue and it should be
2645 * ok to wait for this request to complete.
2647 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2648 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2652 goto check_group_idle
;
2656 * The active queue has requests and isn't expired, allow it to
2659 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2663 * If another queue has a request waiting within our mean seek
2664 * distance, let it run. The expire code will check for close
2665 * cooperators and put the close queue at the front of the service
2666 * tree. If possible, merge the expiring queue with the new cfqq.
2668 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2670 if (!cfqq
->new_cfqq
)
2671 cfq_setup_merge(cfqq
, new_cfqq
);
2676 * No requests pending. If the active queue still has requests in
2677 * flight or is idling for a new request, allow either of these
2678 * conditions to happen (or time out) before selecting a new queue.
2680 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2686 * This is a deep seek queue, but the device is much faster than
2687 * the queue can deliver, don't idle
2689 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2690 (cfq_cfqq_slice_new(cfqq
) ||
2691 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2692 cfq_clear_cfqq_deep(cfqq
);
2693 cfq_clear_cfqq_idle_window(cfqq
);
2696 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2702 * If group idle is enabled and there are requests dispatched from
2703 * this group, wait for requests to complete.
2706 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2707 cfqq
->cfqg
->dispatched
&&
2708 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2714 cfq_slice_expired(cfqd
, 0);
2717 * Current queue expired. Check if we have to switch to a new
2721 cfq_choose_cfqg(cfqd
);
2723 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2728 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2732 while (cfqq
->next_rq
) {
2733 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2737 BUG_ON(!list_empty(&cfqq
->fifo
));
2739 /* By default cfqq is not expired if it is empty. Do it explicitly */
2740 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2745 * Drain our current requests. Used for barriers and when switching
2746 * io schedulers on-the-fly.
2748 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2750 struct cfq_queue
*cfqq
;
2753 /* Expire the timeslice of the current active queue first */
2754 cfq_slice_expired(cfqd
, 0);
2755 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2756 __cfq_set_active_queue(cfqd
, cfqq
);
2757 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2760 BUG_ON(cfqd
->busy_queues
);
2762 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2766 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2767 struct cfq_queue
*cfqq
)
2769 /* the queue hasn't finished any request, can't estimate */
2770 if (cfq_cfqq_slice_new(cfqq
))
2772 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2779 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2781 unsigned int max_dispatch
;
2784 * Drain async requests before we start sync IO
2786 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2790 * If this is an async queue and we have sync IO in flight, let it wait
2792 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2795 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2796 if (cfq_class_idle(cfqq
))
2800 * Does this cfqq already have too much IO in flight?
2802 if (cfqq
->dispatched
>= max_dispatch
) {
2803 bool promote_sync
= false;
2805 * idle queue must always only have a single IO in flight
2807 if (cfq_class_idle(cfqq
))
2811 * If there is only one sync queue
2812 * we can ignore async queue here and give the sync
2813 * queue no dispatch limit. The reason is a sync queue can
2814 * preempt async queue, limiting the sync queue doesn't make
2815 * sense. This is useful for aiostress test.
2817 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2818 promote_sync
= true;
2821 * We have other queues, don't allow more IO from this one
2823 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2828 * Sole queue user, no limit
2830 if (cfqd
->busy_queues
== 1 || promote_sync
)
2834 * Normally we start throttling cfqq when cfq_quantum/2
2835 * requests have been dispatched. But we can drive
2836 * deeper queue depths at the beginning of slice
2837 * subjected to upper limit of cfq_quantum.
2839 max_dispatch
= cfqd
->cfq_quantum
;
2843 * Async queues must wait a bit before being allowed dispatch.
2844 * We also ramp up the dispatch depth gradually for async IO,
2845 * based on the last sync IO we serviced
2847 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2848 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2851 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2852 if (!depth
&& !cfqq
->dispatched
)
2854 if (depth
< max_dispatch
)
2855 max_dispatch
= depth
;
2859 * If we're below the current max, allow a dispatch
2861 return cfqq
->dispatched
< max_dispatch
;
2865 * Dispatch a request from cfqq, moving them to the request queue
2868 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2872 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2874 if (!cfq_may_dispatch(cfqd
, cfqq
))
2878 * follow expired path, else get first next available
2880 rq
= cfq_check_fifo(cfqq
);
2885 * insert request into driver dispatch list
2887 cfq_dispatch_insert(cfqd
->queue
, rq
);
2889 if (!cfqd
->active_cic
) {
2890 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
2892 atomic_long_inc(&cic
->icq
.ioc
->refcount
);
2893 cfqd
->active_cic
= cic
;
2900 * Find the cfqq that we need to service and move a request from that to the
2903 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2905 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2906 struct cfq_queue
*cfqq
;
2908 if (!cfqd
->busy_queues
)
2911 if (unlikely(force
))
2912 return cfq_forced_dispatch(cfqd
);
2914 cfqq
= cfq_select_queue(cfqd
);
2919 * Dispatch a request from this cfqq, if it is allowed
2921 if (!cfq_dispatch_request(cfqd
, cfqq
))
2924 cfqq
->slice_dispatch
++;
2925 cfq_clear_cfqq_must_dispatch(cfqq
);
2928 * expire an async queue immediately if it has used up its slice. idle
2929 * queue always expire after 1 dispatch round.
2931 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2932 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2933 cfq_class_idle(cfqq
))) {
2934 cfqq
->slice_end
= jiffies
+ 1;
2935 cfq_slice_expired(cfqd
, 0);
2938 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2943 * task holds one reference to the queue, dropped when task exits. each rq
2944 * in-flight on this queue also holds a reference, dropped when rq is freed.
2946 * Each cfq queue took a reference on the parent group. Drop it now.
2947 * queue lock must be held here.
2949 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2951 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2952 struct cfq_group
*cfqg
;
2954 BUG_ON(cfqq
->ref
<= 0);
2960 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2961 BUG_ON(rb_first(&cfqq
->sort_list
));
2962 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2965 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2966 __cfq_slice_expired(cfqd
, cfqq
, 0);
2967 cfq_schedule_dispatch(cfqd
);
2970 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2971 kmem_cache_free(cfq_pool
, cfqq
);
2975 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2977 struct cfq_queue
*__cfqq
, *next
;
2980 * If this queue was scheduled to merge with another queue, be
2981 * sure to drop the reference taken on that queue (and others in
2982 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2984 __cfqq
= cfqq
->new_cfqq
;
2986 if (__cfqq
== cfqq
) {
2987 WARN(1, "cfqq->new_cfqq loop detected\n");
2990 next
= __cfqq
->new_cfqq
;
2991 cfq_put_queue(__cfqq
);
2996 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2998 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2999 __cfq_slice_expired(cfqd
, cfqq
, 0);
3000 cfq_schedule_dispatch(cfqd
);
3003 cfq_put_cooperator(cfqq
);
3005 cfq_put_queue(cfqq
);
3008 static void cfq_init_icq(struct io_cq
*icq
)
3010 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3012 cic
->ttime
.last_end_request
= jiffies
;
3015 static void cfq_exit_icq(struct io_cq
*icq
)
3017 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3018 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3020 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
3021 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
3022 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
3025 if (cic
->cfqq
[BLK_RW_SYNC
]) {
3026 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
3027 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
3031 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct cfq_io_cq
*cic
)
3033 struct task_struct
*tsk
= current
;
3036 if (!cfq_cfqq_prio_changed(cfqq
))
3039 ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3040 switch (ioprio_class
) {
3042 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
3043 case IOPRIO_CLASS_NONE
:
3045 * no prio set, inherit CPU scheduling settings
3047 cfqq
->ioprio
= task_nice_ioprio(tsk
);
3048 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
3050 case IOPRIO_CLASS_RT
:
3051 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3052 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
3054 case IOPRIO_CLASS_BE
:
3055 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3056 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3058 case IOPRIO_CLASS_IDLE
:
3059 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
3061 cfq_clear_cfqq_idle_window(cfqq
);
3066 * keep track of original prio settings in case we have to temporarily
3067 * elevate the priority of this queue
3069 cfqq
->org_ioprio
= cfqq
->ioprio
;
3070 cfq_clear_cfqq_prio_changed(cfqq
);
3073 static void check_ioprio_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3075 int ioprio
= cic
->icq
.ioc
->ioprio
;
3076 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3077 struct cfq_queue
*cfqq
;
3080 * Check whether ioprio has changed. The condition may trigger
3081 * spuriously on a newly created cic but there's no harm.
3083 if (unlikely(!cfqd
) || likely(cic
->ioprio
== ioprio
))
3086 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
3088 struct cfq_queue
*new_cfqq
;
3089 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
, bio
,
3092 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
3093 cfq_put_queue(cfqq
);
3097 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
3099 cfq_mark_cfqq_prio_changed(cfqq
);
3101 cic
->ioprio
= ioprio
;
3104 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3105 pid_t pid
, bool is_sync
)
3107 RB_CLEAR_NODE(&cfqq
->rb_node
);
3108 RB_CLEAR_NODE(&cfqq
->p_node
);
3109 INIT_LIST_HEAD(&cfqq
->fifo
);
3114 cfq_mark_cfqq_prio_changed(cfqq
);
3117 if (!cfq_class_idle(cfqq
))
3118 cfq_mark_cfqq_idle_window(cfqq
);
3119 cfq_mark_cfqq_sync(cfqq
);
3124 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3125 static void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3127 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3128 struct cfq_queue
*sync_cfqq
;
3132 id
= bio_blkio_cgroup(bio
)->id
;
3136 * Check whether blkcg has changed. The condition may trigger
3137 * spuriously on a newly created cic but there's no harm.
3139 if (unlikely(!cfqd
) || likely(cic
->blkcg_id
== id
))
3142 sync_cfqq
= cic_to_cfqq(cic
, 1);
3145 * Drop reference to sync queue. A new sync queue will be
3146 * assigned in new group upon arrival of a fresh request.
3148 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
3149 cic_set_cfqq(cic
, NULL
, 1);
3150 cfq_put_queue(sync_cfqq
);
3156 static inline void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
) { }
3157 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3159 static struct cfq_queue
*
3160 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3161 struct bio
*bio
, gfp_t gfp_mask
)
3163 struct blkio_cgroup
*blkcg
;
3164 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
3165 struct cfq_group
*cfqg
;
3170 blkcg
= bio_blkio_cgroup(bio
);
3171 cfqg
= cfq_lookup_create_cfqg(cfqd
, blkcg
);
3172 cfqq
= cic_to_cfqq(cic
, is_sync
);
3175 * Always try a new alloc if we fell back to the OOM cfqq
3176 * originally, since it should just be a temporary situation.
3178 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3183 } else if (gfp_mask
& __GFP_WAIT
) {
3185 spin_unlock_irq(cfqd
->queue
->queue_lock
);
3186 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
3187 gfp_mask
| __GFP_ZERO
,
3189 spin_lock_irq(cfqd
->queue
->queue_lock
);
3193 cfqq
= kmem_cache_alloc_node(cfq_pool
,
3194 gfp_mask
| __GFP_ZERO
,
3199 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
3200 cfq_init_prio_data(cfqq
, cic
);
3201 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
3202 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
3204 cfqq
= &cfqd
->oom_cfqq
;
3208 kmem_cache_free(cfq_pool
, new_cfqq
);
3214 static struct cfq_queue
**
3215 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
3217 switch (ioprio_class
) {
3218 case IOPRIO_CLASS_RT
:
3219 return &cfqd
->async_cfqq
[0][ioprio
];
3220 case IOPRIO_CLASS_NONE
:
3221 ioprio
= IOPRIO_NORM
;
3223 case IOPRIO_CLASS_BE
:
3224 return &cfqd
->async_cfqq
[1][ioprio
];
3225 case IOPRIO_CLASS_IDLE
:
3226 return &cfqd
->async_idle_cfqq
;
3232 static struct cfq_queue
*
3233 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3234 struct bio
*bio
, gfp_t gfp_mask
)
3236 const int ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3237 const int ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3238 struct cfq_queue
**async_cfqq
= NULL
;
3239 struct cfq_queue
*cfqq
= NULL
;
3242 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
3247 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3250 * pin the queue now that it's allocated, scheduler exit will prune it
3252 if (!is_sync
&& !(*async_cfqq
)) {
3262 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3264 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3265 elapsed
= min(elapsed
, 2UL * slice_idle
);
3267 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3268 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3269 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3273 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3274 struct cfq_io_cq
*cic
)
3276 if (cfq_cfqq_sync(cfqq
)) {
3277 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3278 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3279 cfqd
->cfq_slice_idle
);
3281 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3282 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3287 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3291 sector_t n_sec
= blk_rq_sectors(rq
);
3292 if (cfqq
->last_request_pos
) {
3293 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3294 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3296 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3299 cfqq
->seek_history
<<= 1;
3300 if (blk_queue_nonrot(cfqd
->queue
))
3301 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3303 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3307 * Disable idle window if the process thinks too long or seeks so much that
3311 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3312 struct cfq_io_cq
*cic
)
3314 int old_idle
, enable_idle
;
3317 * Don't idle for async or idle io prio class
3319 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3322 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3324 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3325 cfq_mark_cfqq_deep(cfqq
);
3327 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3329 else if (!atomic_read(&cic
->icq
.ioc
->active_ref
) ||
3330 !cfqd
->cfq_slice_idle
||
3331 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3333 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3334 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3340 if (old_idle
!= enable_idle
) {
3341 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3343 cfq_mark_cfqq_idle_window(cfqq
);
3345 cfq_clear_cfqq_idle_window(cfqq
);
3350 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3351 * no or if we aren't sure, a 1 will cause a preempt.
3354 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3357 struct cfq_queue
*cfqq
;
3359 cfqq
= cfqd
->active_queue
;
3363 if (cfq_class_idle(new_cfqq
))
3366 if (cfq_class_idle(cfqq
))
3370 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3372 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3376 * if the new request is sync, but the currently running queue is
3377 * not, let the sync request have priority.
3379 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3382 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3385 if (cfq_slice_used(cfqq
))
3388 /* Allow preemption only if we are idling on sync-noidle tree */
3389 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3390 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3391 new_cfqq
->service_tree
->count
== 2 &&
3392 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3396 * So both queues are sync. Let the new request get disk time if
3397 * it's a metadata request and the current queue is doing regular IO.
3399 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3403 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3405 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3408 /* An idle queue should not be idle now for some reason */
3409 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3412 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3416 * if this request is as-good as one we would expect from the
3417 * current cfqq, let it preempt
3419 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3426 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3427 * let it have half of its nominal slice.
3429 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3431 enum wl_type_t old_type
= cfqq_type(cfqd
->active_queue
);
3433 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3434 cfq_slice_expired(cfqd
, 1);
3437 * workload type is changed, don't save slice, otherwise preempt
3440 if (old_type
!= cfqq_type(cfqq
))
3441 cfqq
->cfqg
->saved_workload_slice
= 0;
3444 * Put the new queue at the front of the of the current list,
3445 * so we know that it will be selected next.
3447 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3449 cfq_service_tree_add(cfqd
, cfqq
, 1);
3451 cfqq
->slice_end
= 0;
3452 cfq_mark_cfqq_slice_new(cfqq
);
3456 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3457 * something we should do about it
3460 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3463 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3466 if (rq
->cmd_flags
& REQ_PRIO
)
3467 cfqq
->prio_pending
++;
3469 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3470 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3471 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3473 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3475 if (cfqq
== cfqd
->active_queue
) {
3477 * Remember that we saw a request from this process, but
3478 * don't start queuing just yet. Otherwise we risk seeing lots
3479 * of tiny requests, because we disrupt the normal plugging
3480 * and merging. If the request is already larger than a single
3481 * page, let it rip immediately. For that case we assume that
3482 * merging is already done. Ditto for a busy system that
3483 * has other work pending, don't risk delaying until the
3484 * idle timer unplug to continue working.
3486 if (cfq_cfqq_wait_request(cfqq
)) {
3487 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3488 cfqd
->busy_queues
> 1) {
3489 cfq_del_timer(cfqd
, cfqq
);
3490 cfq_clear_cfqq_wait_request(cfqq
);
3491 __blk_run_queue(cfqd
->queue
);
3493 cfqg_stats_update_idle_time(cfqq
->cfqg
);
3494 cfq_mark_cfqq_must_dispatch(cfqq
);
3497 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3499 * not the active queue - expire current slice if it is
3500 * idle and has expired it's mean thinktime or this new queue
3501 * has some old slice time left and is of higher priority or
3502 * this new queue is RT and the current one is BE
3504 cfq_preempt_queue(cfqd
, cfqq
);
3505 __blk_run_queue(cfqd
->queue
);
3509 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3511 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3512 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3514 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3515 cfq_init_prio_data(cfqq
, RQ_CIC(rq
));
3517 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3518 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3520 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqd
->serving_group
,
3522 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3526 * Update hw_tag based on peak queue depth over 50 samples under
3529 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3531 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3533 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3534 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3536 if (cfqd
->hw_tag
== 1)
3539 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3540 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3544 * If active queue hasn't enough requests and can idle, cfq might not
3545 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3548 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3549 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3550 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3553 if (cfqd
->hw_tag_samples
++ < 50)
3556 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3562 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3564 struct cfq_io_cq
*cic
= cfqd
->active_cic
;
3566 /* If the queue already has requests, don't wait */
3567 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3570 /* If there are other queues in the group, don't wait */
3571 if (cfqq
->cfqg
->nr_cfqq
> 1)
3574 /* the only queue in the group, but think time is big */
3575 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3578 if (cfq_slice_used(cfqq
))
3581 /* if slice left is less than think time, wait busy */
3582 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3583 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3587 * If think times is less than a jiffy than ttime_mean=0 and above
3588 * will not be true. It might happen that slice has not expired yet
3589 * but will expire soon (4-5 ns) during select_queue(). To cover the
3590 * case where think time is less than a jiffy, mark the queue wait
3591 * busy if only 1 jiffy is left in the slice.
3593 if (cfqq
->slice_end
- jiffies
== 1)
3599 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3601 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3602 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3603 const int sync
= rq_is_sync(rq
);
3607 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3608 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3610 cfq_update_hw_tag(cfqd
);
3612 WARN_ON(!cfqd
->rq_in_driver
);
3613 WARN_ON(!cfqq
->dispatched
);
3614 cfqd
->rq_in_driver
--;
3616 (RQ_CFQG(rq
))->dispatched
--;
3617 cfqg_stats_update_completion(cfqq
->cfqg
, rq_start_time_ns(rq
),
3618 rq_io_start_time_ns(rq
), rq
->cmd_flags
);
3620 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3623 struct cfq_rb_root
*service_tree
;
3625 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3627 if (cfq_cfqq_on_rr(cfqq
))
3628 service_tree
= cfqq
->service_tree
;
3630 service_tree
= service_tree_for(cfqq
->cfqg
,
3631 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3632 service_tree
->ttime
.last_end_request
= now
;
3633 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3634 cfqd
->last_delayed_sync
= now
;
3637 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3638 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3642 * If this is the active queue, check if it needs to be expired,
3643 * or if we want to idle in case it has no pending requests.
3645 if (cfqd
->active_queue
== cfqq
) {
3646 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3648 if (cfq_cfqq_slice_new(cfqq
)) {
3649 cfq_set_prio_slice(cfqd
, cfqq
);
3650 cfq_clear_cfqq_slice_new(cfqq
);
3654 * Should we wait for next request to come in before we expire
3657 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3658 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3659 if (!cfqd
->cfq_slice_idle
)
3660 extend_sl
= cfqd
->cfq_group_idle
;
3661 cfqq
->slice_end
= jiffies
+ extend_sl
;
3662 cfq_mark_cfqq_wait_busy(cfqq
);
3663 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3667 * Idling is not enabled on:
3669 * - idle-priority queues
3671 * - queues with still some requests queued
3672 * - when there is a close cooperator
3674 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3675 cfq_slice_expired(cfqd
, 1);
3676 else if (sync
&& cfqq_empty
&&
3677 !cfq_close_cooperator(cfqd
, cfqq
)) {
3678 cfq_arm_slice_timer(cfqd
);
3682 if (!cfqd
->rq_in_driver
)
3683 cfq_schedule_dispatch(cfqd
);
3686 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3688 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3689 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3690 return ELV_MQUEUE_MUST
;
3693 return ELV_MQUEUE_MAY
;
3696 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3698 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3699 struct task_struct
*tsk
= current
;
3700 struct cfq_io_cq
*cic
;
3701 struct cfq_queue
*cfqq
;
3704 * don't force setup of a queue from here, as a call to may_queue
3705 * does not necessarily imply that a request actually will be queued.
3706 * so just lookup a possibly existing queue, or return 'may queue'
3709 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3711 return ELV_MQUEUE_MAY
;
3713 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3715 cfq_init_prio_data(cfqq
, cic
);
3717 return __cfq_may_queue(cfqq
);
3720 return ELV_MQUEUE_MAY
;
3724 * queue lock held here
3726 static void cfq_put_request(struct request
*rq
)
3728 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3731 const int rw
= rq_data_dir(rq
);
3733 BUG_ON(!cfqq
->allocated
[rw
]);
3734 cfqq
->allocated
[rw
]--;
3736 /* Put down rq reference on cfqg */
3737 cfqg_put(RQ_CFQG(rq
));
3738 rq
->elv
.priv
[0] = NULL
;
3739 rq
->elv
.priv
[1] = NULL
;
3741 cfq_put_queue(cfqq
);
3745 static struct cfq_queue
*
3746 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_cq
*cic
,
3747 struct cfq_queue
*cfqq
)
3749 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3750 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3751 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3752 cfq_put_queue(cfqq
);
3753 return cic_to_cfqq(cic
, 1);
3757 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3758 * was the last process referring to said cfqq.
3760 static struct cfq_queue
*
3761 split_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
)
3763 if (cfqq_process_refs(cfqq
) == 1) {
3764 cfqq
->pid
= current
->pid
;
3765 cfq_clear_cfqq_coop(cfqq
);
3766 cfq_clear_cfqq_split_coop(cfqq
);
3770 cic_set_cfqq(cic
, NULL
, 1);
3772 cfq_put_cooperator(cfqq
);
3774 cfq_put_queue(cfqq
);
3778 * Allocate cfq data structures associated with this request.
3781 cfq_set_request(struct request_queue
*q
, struct request
*rq
, struct bio
*bio
,
3784 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3785 struct cfq_io_cq
*cic
= icq_to_cic(rq
->elv
.icq
);
3786 const int rw
= rq_data_dir(rq
);
3787 const bool is_sync
= rq_is_sync(rq
);
3788 struct cfq_queue
*cfqq
;
3790 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3792 spin_lock_irq(q
->queue_lock
);
3794 check_ioprio_changed(cic
, bio
);
3795 check_blkcg_changed(cic
, bio
);
3797 cfqq
= cic_to_cfqq(cic
, is_sync
);
3798 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3799 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3800 cic_set_cfqq(cic
, cfqq
, is_sync
);
3803 * If the queue was seeky for too long, break it apart.
3805 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3806 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3807 cfqq
= split_cfqq(cic
, cfqq
);
3813 * Check to see if this queue is scheduled to merge with
3814 * another, closely cooperating queue. The merging of
3815 * queues happens here as it must be done in process context.
3816 * The reference on new_cfqq was taken in merge_cfqqs.
3819 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3822 cfqq
->allocated
[rw
]++;
3825 cfqg_get(cfqq
->cfqg
);
3826 rq
->elv
.priv
[0] = cfqq
;
3827 rq
->elv
.priv
[1] = cfqq
->cfqg
;
3828 spin_unlock_irq(q
->queue_lock
);
3832 static void cfq_kick_queue(struct work_struct
*work
)
3834 struct cfq_data
*cfqd
=
3835 container_of(work
, struct cfq_data
, unplug_work
);
3836 struct request_queue
*q
= cfqd
->queue
;
3838 spin_lock_irq(q
->queue_lock
);
3839 __blk_run_queue(cfqd
->queue
);
3840 spin_unlock_irq(q
->queue_lock
);
3844 * Timer running if the active_queue is currently idling inside its time slice
3846 static void cfq_idle_slice_timer(unsigned long data
)
3848 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3849 struct cfq_queue
*cfqq
;
3850 unsigned long flags
;
3853 cfq_log(cfqd
, "idle timer fired");
3855 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3857 cfqq
= cfqd
->active_queue
;
3862 * We saw a request before the queue expired, let it through
3864 if (cfq_cfqq_must_dispatch(cfqq
))
3870 if (cfq_slice_used(cfqq
))
3874 * only expire and reinvoke request handler, if there are
3875 * other queues with pending requests
3877 if (!cfqd
->busy_queues
)
3881 * not expired and it has a request pending, let it dispatch
3883 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3887 * Queue depth flag is reset only when the idle didn't succeed
3889 cfq_clear_cfqq_deep(cfqq
);
3892 cfq_slice_expired(cfqd
, timed_out
);
3894 cfq_schedule_dispatch(cfqd
);
3896 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3899 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3901 del_timer_sync(&cfqd
->idle_slice_timer
);
3902 cancel_work_sync(&cfqd
->unplug_work
);
3905 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3909 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3910 if (cfqd
->async_cfqq
[0][i
])
3911 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3912 if (cfqd
->async_cfqq
[1][i
])
3913 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3916 if (cfqd
->async_idle_cfqq
)
3917 cfq_put_queue(cfqd
->async_idle_cfqq
);
3920 static void cfq_exit_queue(struct elevator_queue
*e
)
3922 struct cfq_data
*cfqd
= e
->elevator_data
;
3923 struct request_queue
*q
= cfqd
->queue
;
3925 cfq_shutdown_timer_wq(cfqd
);
3927 spin_lock_irq(q
->queue_lock
);
3929 if (cfqd
->active_queue
)
3930 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3932 cfq_put_async_queues(cfqd
);
3934 spin_unlock_irq(q
->queue_lock
);
3936 cfq_shutdown_timer_wq(cfqd
);
3938 #ifndef CONFIG_CFQ_GROUP_IOSCHED
3939 kfree(cfqd
->root_group
);
3941 update_root_blkg_pd(q
, &blkio_policy_cfq
);
3945 static int cfq_init_queue(struct request_queue
*q
)
3947 struct cfq_data
*cfqd
;
3948 struct blkio_group
*blkg __maybe_unused
;
3951 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3956 q
->elevator
->elevator_data
= cfqd
;
3958 /* Init root service tree */
3959 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3961 /* Init root group and prefer root group over other groups by default */
3962 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3964 spin_lock_irq(q
->queue_lock
);
3966 blkg
= blkg_lookup_create(&blkio_root_cgroup
, q
, true);
3968 cfqd
->root_group
= blkg_to_cfqg(blkg
);
3970 spin_unlock_irq(q
->queue_lock
);
3973 cfqd
->root_group
= kzalloc_node(sizeof(*cfqd
->root_group
),
3974 GFP_KERNEL
, cfqd
->queue
->node
);
3975 if (cfqd
->root_group
)
3976 cfq_init_cfqg_base(cfqd
->root_group
);
3978 if (!cfqd
->root_group
) {
3983 cfqd
->root_group
->weight
= 2 * CFQ_WEIGHT_DEFAULT
;
3986 * Not strictly needed (since RB_ROOT just clears the node and we
3987 * zeroed cfqd on alloc), but better be safe in case someone decides
3988 * to add magic to the rb code
3990 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3991 cfqd
->prio_trees
[i
] = RB_ROOT
;
3994 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3995 * Grab a permanent reference to it, so that the normal code flow
3996 * will not attempt to free it. oom_cfqq is linked to root_group
3997 * but shouldn't hold a reference as it'll never be unlinked. Lose
3998 * the reference from linking right away.
4000 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
4001 cfqd
->oom_cfqq
.ref
++;
4003 spin_lock_irq(q
->queue_lock
);
4004 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, cfqd
->root_group
);
4005 cfqg_put(cfqd
->root_group
);
4006 spin_unlock_irq(q
->queue_lock
);
4008 init_timer(&cfqd
->idle_slice_timer
);
4009 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
4010 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
4012 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
4014 cfqd
->cfq_quantum
= cfq_quantum
;
4015 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
4016 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
4017 cfqd
->cfq_back_max
= cfq_back_max
;
4018 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
4019 cfqd
->cfq_slice
[0] = cfq_slice_async
;
4020 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
4021 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
4022 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
4023 cfqd
->cfq_group_idle
= cfq_group_idle
;
4024 cfqd
->cfq_latency
= 1;
4027 * we optimistically start assuming sync ops weren't delayed in last
4028 * second, in order to have larger depth for async operations.
4030 cfqd
->last_delayed_sync
= jiffies
- HZ
;
4035 * sysfs parts below -->
4038 cfq_var_show(unsigned int var
, char *page
)
4040 return sprintf(page
, "%d\n", var
);
4044 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4046 char *p
= (char *) page
;
4048 *var
= simple_strtoul(p
, &p
, 10);
4052 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4053 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4055 struct cfq_data *cfqd = e->elevator_data; \
4056 unsigned int __data = __VAR; \
4058 __data = jiffies_to_msecs(__data); \
4059 return cfq_var_show(__data, (page)); \
4061 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4062 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4063 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4064 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4065 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4066 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4067 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4068 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4069 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4070 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4071 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4072 #undef SHOW_FUNCTION
4074 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4075 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4077 struct cfq_data *cfqd = e->elevator_data; \
4078 unsigned int __data; \
4079 int ret = cfq_var_store(&__data, (page), count); \
4080 if (__data < (MIN)) \
4082 else if (__data > (MAX)) \
4085 *(__PTR) = msecs_to_jiffies(__data); \
4087 *(__PTR) = __data; \
4090 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4091 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4093 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4095 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4096 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4098 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4099 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4100 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4101 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4102 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4104 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4105 #undef STORE_FUNCTION
4107 #define CFQ_ATTR(name) \
4108 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4110 static struct elv_fs_entry cfq_attrs
[] = {
4112 CFQ_ATTR(fifo_expire_sync
),
4113 CFQ_ATTR(fifo_expire_async
),
4114 CFQ_ATTR(back_seek_max
),
4115 CFQ_ATTR(back_seek_penalty
),
4116 CFQ_ATTR(slice_sync
),
4117 CFQ_ATTR(slice_async
),
4118 CFQ_ATTR(slice_async_rq
),
4119 CFQ_ATTR(slice_idle
),
4120 CFQ_ATTR(group_idle
),
4121 CFQ_ATTR(low_latency
),
4125 static struct elevator_type iosched_cfq
= {
4127 .elevator_merge_fn
= cfq_merge
,
4128 .elevator_merged_fn
= cfq_merged_request
,
4129 .elevator_merge_req_fn
= cfq_merged_requests
,
4130 .elevator_allow_merge_fn
= cfq_allow_merge
,
4131 .elevator_bio_merged_fn
= cfq_bio_merged
,
4132 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4133 .elevator_add_req_fn
= cfq_insert_request
,
4134 .elevator_activate_req_fn
= cfq_activate_request
,
4135 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4136 .elevator_completed_req_fn
= cfq_completed_request
,
4137 .elevator_former_req_fn
= elv_rb_former_request
,
4138 .elevator_latter_req_fn
= elv_rb_latter_request
,
4139 .elevator_init_icq_fn
= cfq_init_icq
,
4140 .elevator_exit_icq_fn
= cfq_exit_icq
,
4141 .elevator_set_req_fn
= cfq_set_request
,
4142 .elevator_put_req_fn
= cfq_put_request
,
4143 .elevator_may_queue_fn
= cfq_may_queue
,
4144 .elevator_init_fn
= cfq_init_queue
,
4145 .elevator_exit_fn
= cfq_exit_queue
,
4147 .icq_size
= sizeof(struct cfq_io_cq
),
4148 .icq_align
= __alignof__(struct cfq_io_cq
),
4149 .elevator_attrs
= cfq_attrs
,
4150 .elevator_name
= "cfq",
4151 .elevator_owner
= THIS_MODULE
,
4154 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4155 static struct blkio_policy_type blkio_policy_cfq
= {
4157 .blkio_init_group_fn
= cfq_init_blkio_group
,
4158 .blkio_reset_group_stats_fn
= cfqg_stats_reset
,
4160 .pdata_size
= sizeof(struct cfq_group
),
4161 .cftypes
= cfq_blkcg_files
,
4165 static int __init
cfq_init(void)
4170 * could be 0 on HZ < 1000 setups
4172 if (!cfq_slice_async
)
4173 cfq_slice_async
= 1;
4174 if (!cfq_slice_idle
)
4177 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4178 if (!cfq_group_idle
)
4184 ret
= blkio_policy_register(&blkio_policy_cfq
);
4188 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
4192 ret
= elv_register(&iosched_cfq
);
4199 kmem_cache_destroy(cfq_pool
);
4201 blkio_policy_unregister(&blkio_policy_cfq
);
4205 static void __exit
cfq_exit(void)
4207 blkio_policy_unregister(&blkio_policy_cfq
);
4208 elv_unregister(&iosched_cfq
);
4209 kmem_cache_destroy(cfq_pool
);
4212 module_init(cfq_init
);
4213 module_exit(cfq_exit
);
4215 MODULE_AUTHOR("Jens Axboe");
4216 MODULE_LICENSE("GPL");
4217 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");