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
;
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
;
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 void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
,
545 struct cfq_group
*curr_cfqg
) { }
546 static void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
) { }
547 static void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
) { }
548 static void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
) { }
549 static void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
) { }
550 static void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
) { }
551 static void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
) { }
553 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
555 #ifdef CONFIG_CFQ_GROUP_IOSCHED
557 static inline struct cfq_group
*blkg_to_cfqg(struct blkio_group
*blkg
)
559 return blkg_to_pdata(blkg
, &blkio_policy_cfq
);
562 static inline struct blkio_group
*cfqg_to_blkg(struct cfq_group
*cfqg
)
564 return pdata_to_blkg(cfqg
);
567 static inline void cfqg_get(struct cfq_group
*cfqg
)
569 return blkg_get(cfqg_to_blkg(cfqg
));
572 static inline void cfqg_put(struct cfq_group
*cfqg
)
574 return blkg_put(cfqg_to_blkg(cfqg
));
577 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
578 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
579 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
580 blkg_path(cfqg_to_blkg((cfqq)->cfqg)), ##args)
582 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
583 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
584 blkg_path(cfqg_to_blkg((cfqg))), ##args) \
586 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
587 struct cfq_group
*curr_cfqg
, int rw
)
589 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, 1);
590 cfqg_stats_end_empty_time(&cfqg
->stats
);
591 cfqg_stats_set_start_group_wait_time(cfqg
, curr_cfqg
);
594 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
595 unsigned long time
, unsigned long unaccounted_time
)
597 blkg_stat_add(&cfqg
->stats
.time
, time
);
598 #ifdef CONFIG_DEBUG_BLK_CGROUP
599 blkg_stat_add(&cfqg
->stats
.unaccounted_time
, unaccounted_time
);
603 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
)
605 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, -1);
608 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
)
610 blkg_rwstat_add(&cfqg
->stats
.merged
, rw
, 1);
613 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
614 uint64_t bytes
, int rw
)
616 blkg_stat_add(&cfqg
->stats
.sectors
, bytes
>> 9);
617 blkg_rwstat_add(&cfqg
->stats
.serviced
, rw
, 1);
618 blkg_rwstat_add(&cfqg
->stats
.service_bytes
, rw
, bytes
);
621 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
622 uint64_t start_time
, uint64_t io_start_time
, int rw
)
624 struct cfqg_stats
*stats
= &cfqg
->stats
;
625 unsigned long long now
= sched_clock();
627 if (time_after64(now
, io_start_time
))
628 blkg_rwstat_add(&stats
->service_time
, rw
, now
- io_start_time
);
629 if (time_after64(io_start_time
, start_time
))
630 blkg_rwstat_add(&stats
->wait_time
, rw
,
631 io_start_time
- start_time
);
634 static void cfqg_stats_reset(struct blkio_group
*blkg
)
636 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
637 struct cfqg_stats
*stats
= &cfqg
->stats
;
639 /* queued stats shouldn't be cleared */
640 blkg_rwstat_reset(&stats
->service_bytes
);
641 blkg_rwstat_reset(&stats
->serviced
);
642 blkg_rwstat_reset(&stats
->merged
);
643 blkg_rwstat_reset(&stats
->service_time
);
644 blkg_rwstat_reset(&stats
->wait_time
);
645 blkg_stat_reset(&stats
->time
);
646 #ifdef CONFIG_DEBUG_BLK_CGROUP
647 blkg_stat_reset(&stats
->unaccounted_time
);
648 blkg_stat_reset(&stats
->avg_queue_size_sum
);
649 blkg_stat_reset(&stats
->avg_queue_size_samples
);
650 blkg_stat_reset(&stats
->dequeue
);
651 blkg_stat_reset(&stats
->group_wait_time
);
652 blkg_stat_reset(&stats
->idle_time
);
653 blkg_stat_reset(&stats
->empty_time
);
657 #else /* CONFIG_CFQ_GROUP_IOSCHED */
659 static inline struct cfq_group
*blkg_to_cfqg(struct blkio_group
*blkg
) { return NULL
; }
660 static inline struct blkio_group
*cfqg_to_blkg(struct cfq_group
*cfqg
) { return NULL
; }
661 static inline void cfqg_get(struct cfq_group
*cfqg
) { }
662 static inline void cfqg_put(struct cfq_group
*cfqg
) { }
664 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
665 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
666 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
668 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
669 struct cfq_group
*curr_cfqg
, int rw
) { }
670 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
671 unsigned long time
, unsigned long unaccounted_time
) { }
672 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
) { }
673 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
) { }
674 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
675 uint64_t bytes
, int rw
) { }
676 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
677 uint64_t start_time
, uint64_t io_start_time
, int rw
) { }
679 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
681 #define cfq_log(cfqd, fmt, args...) \
682 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
684 /* Traverses through cfq group service trees */
685 #define for_each_cfqg_st(cfqg, i, j, st) \
686 for (i = 0; i <= IDLE_WORKLOAD; i++) \
687 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
688 : &cfqg->service_tree_idle; \
689 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
690 (i == IDLE_WORKLOAD && j == 0); \
691 j++, st = i < IDLE_WORKLOAD ? \
692 &cfqg->service_trees[i][j]: NULL) \
694 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
695 struct cfq_ttime
*ttime
, bool group_idle
)
698 if (!sample_valid(ttime
->ttime_samples
))
701 slice
= cfqd
->cfq_group_idle
;
703 slice
= cfqd
->cfq_slice_idle
;
704 return ttime
->ttime_mean
> slice
;
707 static inline bool iops_mode(struct cfq_data
*cfqd
)
710 * If we are not idling on queues and it is a NCQ drive, parallel
711 * execution of requests is on and measuring time is not possible
712 * in most of the cases until and unless we drive shallower queue
713 * depths and that becomes a performance bottleneck. In such cases
714 * switch to start providing fairness in terms of number of IOs.
716 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
722 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
724 if (cfq_class_idle(cfqq
))
725 return IDLE_WORKLOAD
;
726 if (cfq_class_rt(cfqq
))
732 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
734 if (!cfq_cfqq_sync(cfqq
))
735 return ASYNC_WORKLOAD
;
736 if (!cfq_cfqq_idle_window(cfqq
))
737 return SYNC_NOIDLE_WORKLOAD
;
738 return SYNC_WORKLOAD
;
741 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
742 struct cfq_data
*cfqd
,
743 struct cfq_group
*cfqg
)
745 if (wl
== IDLE_WORKLOAD
)
746 return cfqg
->service_tree_idle
.count
;
748 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
749 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
750 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
753 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
754 struct cfq_group
*cfqg
)
756 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
757 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
760 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
761 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
,
762 struct cfq_io_cq
*cic
, struct bio
*bio
,
765 static inline struct cfq_io_cq
*icq_to_cic(struct io_cq
*icq
)
767 /* cic->icq is the first member, %NULL will convert to %NULL */
768 return container_of(icq
, struct cfq_io_cq
, icq
);
771 static inline struct cfq_io_cq
*cfq_cic_lookup(struct cfq_data
*cfqd
,
772 struct io_context
*ioc
)
775 return icq_to_cic(ioc_lookup_icq(ioc
, cfqd
->queue
));
779 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_cq
*cic
, bool is_sync
)
781 return cic
->cfqq
[is_sync
];
784 static inline void cic_set_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
,
787 cic
->cfqq
[is_sync
] = cfqq
;
790 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_cq
*cic
)
792 return cic
->icq
.q
->elevator
->elevator_data
;
796 * We regard a request as SYNC, if it's either a read or has the SYNC bit
797 * set (in which case it could also be direct WRITE).
799 static inline bool cfq_bio_sync(struct bio
*bio
)
801 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
805 * scheduler run of queue, if there are requests pending and no one in the
806 * driver that will restart queueing
808 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
810 if (cfqd
->busy_queues
) {
811 cfq_log(cfqd
, "schedule dispatch");
812 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
817 * Scale schedule slice based on io priority. Use the sync time slice only
818 * if a queue is marked sync and has sync io queued. A sync queue with async
819 * io only, should not get full sync slice length.
821 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
824 const int base_slice
= cfqd
->cfq_slice
[sync
];
826 WARN_ON(prio
>= IOPRIO_BE_NR
);
828 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
832 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
834 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
837 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
839 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
841 d
= d
* BLKIO_WEIGHT_DEFAULT
;
842 do_div(d
, cfqg
->weight
);
846 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
848 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
850 min_vdisktime
= vdisktime
;
852 return min_vdisktime
;
855 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
857 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
859 min_vdisktime
= vdisktime
;
861 return min_vdisktime
;
864 static void update_min_vdisktime(struct cfq_rb_root
*st
)
866 struct cfq_group
*cfqg
;
869 cfqg
= rb_entry_cfqg(st
->left
);
870 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
876 * get averaged number of queues of RT/BE priority.
877 * average is updated, with a formula that gives more weight to higher numbers,
878 * to quickly follows sudden increases and decrease slowly
881 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
882 struct cfq_group
*cfqg
, bool rt
)
884 unsigned min_q
, max_q
;
885 unsigned mult
= cfq_hist_divisor
- 1;
886 unsigned round
= cfq_hist_divisor
/ 2;
887 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
889 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
890 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
891 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
893 return cfqg
->busy_queues_avg
[rt
];
896 static inline unsigned
897 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
899 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
901 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
904 static inline unsigned
905 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
907 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
908 if (cfqd
->cfq_latency
) {
910 * interested queues (we consider only the ones with the same
911 * priority class in the cfq group)
913 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
915 unsigned sync_slice
= cfqd
->cfq_slice
[1];
916 unsigned expect_latency
= sync_slice
* iq
;
917 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
919 if (expect_latency
> group_slice
) {
920 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
921 /* scale low_slice according to IO priority
922 * and sync vs async */
924 min(slice
, base_low_slice
* slice
/ sync_slice
);
925 /* the adapted slice value is scaled to fit all iqs
926 * into the target latency */
927 slice
= max(slice
* group_slice
/ expect_latency
,
935 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
937 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
939 cfqq
->slice_start
= jiffies
;
940 cfqq
->slice_end
= jiffies
+ slice
;
941 cfqq
->allocated_slice
= slice
;
942 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
946 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
947 * isn't valid until the first request from the dispatch is activated
948 * and the slice time set.
950 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
952 if (cfq_cfqq_slice_new(cfqq
))
954 if (time_before(jiffies
, cfqq
->slice_end
))
961 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
962 * We choose the request that is closest to the head right now. Distance
963 * behind the head is penalized and only allowed to a certain extent.
965 static struct request
*
966 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
968 sector_t s1
, s2
, d1
= 0, d2
= 0;
969 unsigned long back_max
;
970 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
971 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
972 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
974 if (rq1
== NULL
|| rq1
== rq2
)
979 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
980 return rq_is_sync(rq1
) ? rq1
: rq2
;
982 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
983 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
985 s1
= blk_rq_pos(rq1
);
986 s2
= blk_rq_pos(rq2
);
989 * by definition, 1KiB is 2 sectors
991 back_max
= cfqd
->cfq_back_max
* 2;
994 * Strict one way elevator _except_ in the case where we allow
995 * short backward seeks which are biased as twice the cost of a
996 * similar forward seek.
1000 else if (s1
+ back_max
>= last
)
1001 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
1003 wrap
|= CFQ_RQ1_WRAP
;
1007 else if (s2
+ back_max
>= last
)
1008 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
1010 wrap
|= CFQ_RQ2_WRAP
;
1012 /* Found required data */
1015 * By doing switch() on the bit mask "wrap" we avoid having to
1016 * check two variables for all permutations: --> faster!
1019 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1035 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
1038 * Since both rqs are wrapped,
1039 * start with the one that's further behind head
1040 * (--> only *one* back seek required),
1041 * since back seek takes more time than forward.
1051 * The below is leftmost cache rbtree addon
1053 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
1055 /* Service tree is empty */
1060 root
->left
= rb_first(&root
->rb
);
1063 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
1068 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
1071 root
->left
= rb_first(&root
->rb
);
1074 return rb_entry_cfqg(root
->left
);
1079 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
1085 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
1087 if (root
->left
== n
)
1089 rb_erase_init(n
, &root
->rb
);
1094 * would be nice to take fifo expire time into account as well
1096 static struct request
*
1097 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1098 struct request
*last
)
1100 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
1101 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
1102 struct request
*next
= NULL
, *prev
= NULL
;
1104 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
1107 prev
= rb_entry_rq(rbprev
);
1110 next
= rb_entry_rq(rbnext
);
1112 rbnext
= rb_first(&cfqq
->sort_list
);
1113 if (rbnext
&& rbnext
!= &last
->rb_node
)
1114 next
= rb_entry_rq(rbnext
);
1117 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
1120 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
1121 struct cfq_queue
*cfqq
)
1124 * just an approximation, should be ok.
1126 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
1127 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
1131 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1133 return cfqg
->vdisktime
- st
->min_vdisktime
;
1137 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1139 struct rb_node
**node
= &st
->rb
.rb_node
;
1140 struct rb_node
*parent
= NULL
;
1141 struct cfq_group
*__cfqg
;
1142 s64 key
= cfqg_key(st
, cfqg
);
1145 while (*node
!= NULL
) {
1147 __cfqg
= rb_entry_cfqg(parent
);
1149 if (key
< cfqg_key(st
, __cfqg
))
1150 node
= &parent
->rb_left
;
1152 node
= &parent
->rb_right
;
1158 st
->left
= &cfqg
->rb_node
;
1160 rb_link_node(&cfqg
->rb_node
, parent
, node
);
1161 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
1165 cfq_update_group_weight(struct cfq_group
*cfqg
)
1167 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1168 if (cfqg
->needs_update
) {
1169 cfqg
->weight
= cfqg
->new_weight
;
1170 cfqg
->needs_update
= false;
1175 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1177 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1179 cfq_update_group_weight(cfqg
);
1180 __cfq_group_service_tree_add(st
, cfqg
);
1181 st
->total_weight
+= cfqg
->weight
;
1185 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1187 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1188 struct cfq_group
*__cfqg
;
1192 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1196 * Currently put the group at the end. Later implement something
1197 * so that groups get lesser vtime based on their weights, so that
1198 * if group does not loose all if it was not continuously backlogged.
1200 n
= rb_last(&st
->rb
);
1202 __cfqg
= rb_entry_cfqg(n
);
1203 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
1205 cfqg
->vdisktime
= st
->min_vdisktime
;
1206 cfq_group_service_tree_add(st
, cfqg
);
1210 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1212 st
->total_weight
-= cfqg
->weight
;
1213 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1214 cfq_rb_erase(&cfqg
->rb_node
, st
);
1218 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1220 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1222 BUG_ON(cfqg
->nr_cfqq
< 1);
1225 /* If there are other cfq queues under this group, don't delete it */
1229 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
1230 cfq_group_service_tree_del(st
, cfqg
);
1231 cfqg
->saved_workload_slice
= 0;
1232 cfqg_stats_update_dequeue(cfqg
);
1235 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
1236 unsigned int *unaccounted_time
)
1238 unsigned int slice_used
;
1241 * Queue got expired before even a single request completed or
1242 * got expired immediately after first request completion.
1244 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
1246 * Also charge the seek time incurred to the group, otherwise
1247 * if there are mutiple queues in the group, each can dispatch
1248 * a single request on seeky media and cause lots of seek time
1249 * and group will never know it.
1251 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
1254 slice_used
= jiffies
- cfqq
->slice_start
;
1255 if (slice_used
> cfqq
->allocated_slice
) {
1256 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
1257 slice_used
= cfqq
->allocated_slice
;
1259 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
1260 *unaccounted_time
+= cfqq
->slice_start
-
1261 cfqq
->dispatch_start
;
1267 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
1268 struct cfq_queue
*cfqq
)
1270 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1271 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
1272 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
1273 - cfqg
->service_tree_idle
.count
;
1275 BUG_ON(nr_sync
< 0);
1276 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
1278 if (iops_mode(cfqd
))
1279 charge
= cfqq
->slice_dispatch
;
1280 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
1281 charge
= cfqq
->allocated_slice
;
1283 /* Can't update vdisktime while group is on service tree */
1284 cfq_group_service_tree_del(st
, cfqg
);
1285 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
1286 /* If a new weight was requested, update now, off tree */
1287 cfq_group_service_tree_add(st
, cfqg
);
1289 /* This group is being expired. Save the context */
1290 if (time_after(cfqd
->workload_expires
, jiffies
)) {
1291 cfqg
->saved_workload_slice
= cfqd
->workload_expires
1293 cfqg
->saved_workload
= cfqd
->serving_type
;
1294 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
1296 cfqg
->saved_workload_slice
= 0;
1298 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1300 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1301 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1302 used_sl
, cfqq
->slice_dispatch
, charge
,
1303 iops_mode(cfqd
), cfqq
->nr_sectors
);
1304 cfqg_stats_update_timeslice_used(cfqg
, used_sl
, unaccounted_sl
);
1305 cfqg_stats_set_start_empty_time(cfqg
);
1309 * cfq_init_cfqg_base - initialize base part of a cfq_group
1310 * @cfqg: cfq_group to initialize
1312 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1313 * is enabled or not.
1315 static void cfq_init_cfqg_base(struct cfq_group
*cfqg
)
1317 struct cfq_rb_root
*st
;
1320 for_each_cfqg_st(cfqg
, i
, j
, st
)
1322 RB_CLEAR_NODE(&cfqg
->rb_node
);
1324 cfqg
->ttime
.last_end_request
= jiffies
;
1327 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1328 static void cfq_update_blkio_group_weight(struct blkio_group
*blkg
,
1329 unsigned int weight
)
1331 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1333 cfqg
->new_weight
= weight
;
1334 cfqg
->needs_update
= true;
1337 static void cfq_init_blkio_group(struct blkio_group
*blkg
)
1339 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1341 cfq_init_cfqg_base(cfqg
);
1342 cfqg
->weight
= blkg
->blkcg
->weight
;
1346 * Search for the cfq group current task belongs to. request_queue lock must
1349 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1350 struct blkio_cgroup
*blkcg
)
1352 struct request_queue
*q
= cfqd
->queue
;
1353 struct cfq_group
*cfqg
= NULL
;
1355 /* avoid lookup for the common case where there's no blkio cgroup */
1356 if (blkcg
== &blkio_root_cgroup
) {
1357 cfqg
= cfqd
->root_group
;
1359 struct blkio_group
*blkg
;
1361 blkg
= blkg_lookup_create(blkcg
, q
, false);
1363 cfqg
= blkg_to_cfqg(blkg
);
1369 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1371 /* Currently, all async queues are mapped to root group */
1372 if (!cfq_cfqq_sync(cfqq
))
1373 cfqg
= cfqq
->cfqd
->root_group
;
1376 /* cfqq reference on cfqg */
1380 static u64
blkg_prfill_weight_device(struct seq_file
*sf
,
1381 struct blkg_policy_data
*pd
, int off
)
1383 if (!pd
->conf
.weight
)
1385 return __blkg_prfill_u64(sf
, pd
, pd
->conf
.weight
);
1388 static int blkcg_print_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1389 struct seq_file
*sf
)
1391 blkcg_print_blkgs(sf
, cgroup_to_blkio_cgroup(cgrp
),
1392 blkg_prfill_weight_device
, BLKIO_POLICY_PROP
, 0,
1397 static int blkcg_print_weight(struct cgroup
*cgrp
, struct cftype
*cft
,
1398 struct seq_file
*sf
)
1400 seq_printf(sf
, "%u\n", cgroup_to_blkio_cgroup(cgrp
)->weight
);
1404 static int blkcg_set_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1407 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1408 struct blkg_policy_data
*pd
;
1409 struct blkg_conf_ctx ctx
;
1412 ret
= blkg_conf_prep(blkcg
, buf
, &ctx
);
1417 pd
= ctx
.blkg
->pd
[BLKIO_POLICY_PROP
];
1418 if (pd
&& (!ctx
.v
|| (ctx
.v
>= BLKIO_WEIGHT_MIN
&&
1419 ctx
.v
<= BLKIO_WEIGHT_MAX
))) {
1420 pd
->conf
.weight
= ctx
.v
;
1421 cfq_update_blkio_group_weight(ctx
.blkg
, ctx
.v
?: blkcg
->weight
);
1425 blkg_conf_finish(&ctx
);
1429 static int blkcg_set_weight(struct cgroup
*cgrp
, struct cftype
*cft
, u64 val
)
1431 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1432 struct blkio_group
*blkg
;
1433 struct hlist_node
*n
;
1435 if (val
< BLKIO_WEIGHT_MIN
|| val
> BLKIO_WEIGHT_MAX
)
1438 spin_lock_irq(&blkcg
->lock
);
1439 blkcg
->weight
= (unsigned int)val
;
1441 hlist_for_each_entry(blkg
, n
, &blkcg
->blkg_list
, blkcg_node
) {
1442 struct blkg_policy_data
*pd
= blkg
->pd
[BLKIO_POLICY_PROP
];
1444 if (pd
&& !pd
->conf
.weight
)
1445 cfq_update_blkio_group_weight(blkg
, blkcg
->weight
);
1448 spin_unlock_irq(&blkcg
->lock
);
1452 #ifdef CONFIG_DEBUG_BLK_CGROUP
1453 static u64
cfqg_prfill_avg_queue_size(struct seq_file
*sf
,
1454 struct blkg_policy_data
*pd
, int off
)
1456 struct cfq_group
*cfqg
= (void *)pd
->pdata
;
1457 u64 samples
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_samples
);
1461 v
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_sum
);
1464 __blkg_prfill_u64(sf
, pd
, v
);
1468 /* print avg_queue_size */
1469 static int cfqg_print_avg_queue_size(struct cgroup
*cgrp
, struct cftype
*cft
,
1470 struct seq_file
*sf
)
1472 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgrp
);
1474 blkcg_print_blkgs(sf
, blkcg
, cfqg_prfill_avg_queue_size
,
1475 BLKIO_POLICY_PROP
, 0, false);
1478 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1480 static struct cftype cfq_blkcg_files
[] = {
1482 .name
= "weight_device",
1483 .read_seq_string
= blkcg_print_weight_device
,
1484 .write_string
= blkcg_set_weight_device
,
1485 .max_write_len
= 256,
1489 .read_seq_string
= blkcg_print_weight
,
1490 .write_u64
= blkcg_set_weight
,
1494 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1495 offsetof(struct cfq_group
, stats
.time
)),
1496 .read_seq_string
= blkcg_print_stat
,
1500 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1501 offsetof(struct cfq_group
, stats
.sectors
)),
1502 .read_seq_string
= blkcg_print_stat
,
1505 .name
= "io_service_bytes",
1506 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1507 offsetof(struct cfq_group
, stats
.service_bytes
)),
1508 .read_seq_string
= blkcg_print_rwstat
,
1511 .name
= "io_serviced",
1512 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1513 offsetof(struct cfq_group
, stats
.serviced
)),
1514 .read_seq_string
= blkcg_print_rwstat
,
1517 .name
= "io_service_time",
1518 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1519 offsetof(struct cfq_group
, stats
.service_time
)),
1520 .read_seq_string
= blkcg_print_rwstat
,
1523 .name
= "io_wait_time",
1524 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1525 offsetof(struct cfq_group
, stats
.wait_time
)),
1526 .read_seq_string
= blkcg_print_rwstat
,
1529 .name
= "io_merged",
1530 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1531 offsetof(struct cfq_group
, stats
.merged
)),
1532 .read_seq_string
= blkcg_print_rwstat
,
1535 .name
= "io_queued",
1536 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1537 offsetof(struct cfq_group
, stats
.queued
)),
1538 .read_seq_string
= blkcg_print_rwstat
,
1540 #ifdef CONFIG_DEBUG_BLK_CGROUP
1542 .name
= "avg_queue_size",
1543 .read_seq_string
= cfqg_print_avg_queue_size
,
1546 .name
= "group_wait_time",
1547 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1548 offsetof(struct cfq_group
, stats
.group_wait_time
)),
1549 .read_seq_string
= blkcg_print_stat
,
1552 .name
= "idle_time",
1553 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1554 offsetof(struct cfq_group
, stats
.idle_time
)),
1555 .read_seq_string
= blkcg_print_stat
,
1558 .name
= "empty_time",
1559 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1560 offsetof(struct cfq_group
, stats
.empty_time
)),
1561 .read_seq_string
= blkcg_print_stat
,
1565 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1566 offsetof(struct cfq_group
, stats
.dequeue
)),
1567 .read_seq_string
= blkcg_print_stat
,
1570 .name
= "unaccounted_time",
1571 .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP
,
1572 offsetof(struct cfq_group
, stats
.unaccounted_time
)),
1573 .read_seq_string
= blkcg_print_stat
,
1575 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1578 #else /* GROUP_IOSCHED */
1579 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1580 struct blkio_cgroup
*blkcg
)
1582 return cfqd
->root_group
;
1586 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1590 #endif /* GROUP_IOSCHED */
1593 * The cfqd->service_trees holds all pending cfq_queue's that have
1594 * requests waiting to be processed. It is sorted in the order that
1595 * we will service the queues.
1597 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1600 struct rb_node
**p
, *parent
;
1601 struct cfq_queue
*__cfqq
;
1602 unsigned long rb_key
;
1603 struct cfq_rb_root
*service_tree
;
1607 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1609 if (cfq_class_idle(cfqq
)) {
1610 rb_key
= CFQ_IDLE_DELAY
;
1611 parent
= rb_last(&service_tree
->rb
);
1612 if (parent
&& parent
!= &cfqq
->rb_node
) {
1613 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1614 rb_key
+= __cfqq
->rb_key
;
1617 } else if (!add_front
) {
1619 * Get our rb key offset. Subtract any residual slice
1620 * value carried from last service. A negative resid
1621 * count indicates slice overrun, and this should position
1622 * the next service time further away in the tree.
1624 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1625 rb_key
-= cfqq
->slice_resid
;
1626 cfqq
->slice_resid
= 0;
1629 __cfqq
= cfq_rb_first(service_tree
);
1630 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1633 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1636 * same position, nothing more to do
1638 if (rb_key
== cfqq
->rb_key
&&
1639 cfqq
->service_tree
== service_tree
)
1642 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1643 cfqq
->service_tree
= NULL
;
1648 cfqq
->service_tree
= service_tree
;
1649 p
= &service_tree
->rb
.rb_node
;
1654 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1657 * sort by key, that represents service time.
1659 if (time_before(rb_key
, __cfqq
->rb_key
))
1662 n
= &(*p
)->rb_right
;
1670 service_tree
->left
= &cfqq
->rb_node
;
1672 cfqq
->rb_key
= rb_key
;
1673 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1674 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1675 service_tree
->count
++;
1676 if (add_front
|| !new_cfqq
)
1678 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1681 static struct cfq_queue
*
1682 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1683 sector_t sector
, struct rb_node
**ret_parent
,
1684 struct rb_node
***rb_link
)
1686 struct rb_node
**p
, *parent
;
1687 struct cfq_queue
*cfqq
= NULL
;
1695 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1698 * Sort strictly based on sector. Smallest to the left,
1699 * largest to the right.
1701 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1702 n
= &(*p
)->rb_right
;
1703 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1711 *ret_parent
= parent
;
1717 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1719 struct rb_node
**p
, *parent
;
1720 struct cfq_queue
*__cfqq
;
1723 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1724 cfqq
->p_root
= NULL
;
1727 if (cfq_class_idle(cfqq
))
1732 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1733 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1734 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1736 rb_link_node(&cfqq
->p_node
, parent
, p
);
1737 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1739 cfqq
->p_root
= NULL
;
1743 * Update cfqq's position in the service tree.
1745 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1748 * Resorting requires the cfqq to be on the RR list already.
1750 if (cfq_cfqq_on_rr(cfqq
)) {
1751 cfq_service_tree_add(cfqd
, cfqq
, 0);
1752 cfq_prio_tree_add(cfqd
, cfqq
);
1757 * add to busy list of queues for service, trying to be fair in ordering
1758 * the pending list according to last request service
1760 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1762 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1763 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1764 cfq_mark_cfqq_on_rr(cfqq
);
1765 cfqd
->busy_queues
++;
1766 if (cfq_cfqq_sync(cfqq
))
1767 cfqd
->busy_sync_queues
++;
1769 cfq_resort_rr_list(cfqd
, cfqq
);
1773 * Called when the cfqq no longer has requests pending, remove it from
1776 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1778 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1779 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1780 cfq_clear_cfqq_on_rr(cfqq
);
1782 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1783 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1784 cfqq
->service_tree
= NULL
;
1787 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1788 cfqq
->p_root
= NULL
;
1791 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1792 BUG_ON(!cfqd
->busy_queues
);
1793 cfqd
->busy_queues
--;
1794 if (cfq_cfqq_sync(cfqq
))
1795 cfqd
->busy_sync_queues
--;
1799 * rb tree support functions
1801 static void cfq_del_rq_rb(struct request
*rq
)
1803 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1804 const int sync
= rq_is_sync(rq
);
1806 BUG_ON(!cfqq
->queued
[sync
]);
1807 cfqq
->queued
[sync
]--;
1809 elv_rb_del(&cfqq
->sort_list
, rq
);
1811 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1813 * Queue will be deleted from service tree when we actually
1814 * expire it later. Right now just remove it from prio tree
1818 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1819 cfqq
->p_root
= NULL
;
1824 static void cfq_add_rq_rb(struct request
*rq
)
1826 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1827 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1828 struct request
*prev
;
1830 cfqq
->queued
[rq_is_sync(rq
)]++;
1832 elv_rb_add(&cfqq
->sort_list
, rq
);
1834 if (!cfq_cfqq_on_rr(cfqq
))
1835 cfq_add_cfqq_rr(cfqd
, cfqq
);
1838 * check if this request is a better next-serve candidate
1840 prev
= cfqq
->next_rq
;
1841 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1844 * adjust priority tree position, if ->next_rq changes
1846 if (prev
!= cfqq
->next_rq
)
1847 cfq_prio_tree_add(cfqd
, cfqq
);
1849 BUG_ON(!cfqq
->next_rq
);
1852 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1854 elv_rb_del(&cfqq
->sort_list
, rq
);
1855 cfqq
->queued
[rq_is_sync(rq
)]--;
1856 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1858 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqq
->cfqd
->serving_group
,
1862 static struct request
*
1863 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1865 struct task_struct
*tsk
= current
;
1866 struct cfq_io_cq
*cic
;
1867 struct cfq_queue
*cfqq
;
1869 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1873 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1875 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1877 return elv_rb_find(&cfqq
->sort_list
, sector
);
1883 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1885 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1887 cfqd
->rq_in_driver
++;
1888 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1889 cfqd
->rq_in_driver
);
1891 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1894 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1896 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1898 WARN_ON(!cfqd
->rq_in_driver
);
1899 cfqd
->rq_in_driver
--;
1900 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1901 cfqd
->rq_in_driver
);
1904 static void cfq_remove_request(struct request
*rq
)
1906 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1908 if (cfqq
->next_rq
== rq
)
1909 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1911 list_del_init(&rq
->queuelist
);
1914 cfqq
->cfqd
->rq_queued
--;
1915 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1916 if (rq
->cmd_flags
& REQ_PRIO
) {
1917 WARN_ON(!cfqq
->prio_pending
);
1918 cfqq
->prio_pending
--;
1922 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1925 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1926 struct request
*__rq
;
1928 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1929 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1931 return ELEVATOR_FRONT_MERGE
;
1934 return ELEVATOR_NO_MERGE
;
1937 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1940 if (type
== ELEVATOR_FRONT_MERGE
) {
1941 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1943 cfq_reposition_rq_rb(cfqq
, req
);
1947 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1950 cfqg_stats_update_io_merged(RQ_CFQG(req
), bio
->bi_rw
);
1954 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1955 struct request
*next
)
1957 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1958 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1961 * reposition in fifo if next is older than rq
1963 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1964 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1965 list_move(&rq
->queuelist
, &next
->queuelist
);
1966 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1969 if (cfqq
->next_rq
== next
)
1971 cfq_remove_request(next
);
1972 cfqg_stats_update_io_merged(RQ_CFQG(rq
), next
->cmd_flags
);
1974 cfqq
= RQ_CFQQ(next
);
1976 * all requests of this queue are merged to other queues, delete it
1977 * from the service tree. If it's the active_queue,
1978 * cfq_dispatch_requests() will choose to expire it or do idle
1980 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
) &&
1981 cfqq
!= cfqd
->active_queue
)
1982 cfq_del_cfqq_rr(cfqd
, cfqq
);
1985 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1988 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1989 struct cfq_io_cq
*cic
;
1990 struct cfq_queue
*cfqq
;
1993 * Disallow merge of a sync bio into an async request.
1995 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1999 * Lookup the cfqq that this bio will be queued with and allow
2000 * merge only if rq is queued there.
2002 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
2006 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
2007 return cfqq
== RQ_CFQQ(rq
);
2010 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2012 del_timer(&cfqd
->idle_slice_timer
);
2013 cfqg_stats_update_idle_time(cfqq
->cfqg
);
2016 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
2017 struct cfq_queue
*cfqq
)
2020 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
2021 cfqd
->serving_prio
, cfqd
->serving_type
);
2022 cfqg_stats_update_avg_queue_size(cfqq
->cfqg
);
2023 cfqq
->slice_start
= 0;
2024 cfqq
->dispatch_start
= jiffies
;
2025 cfqq
->allocated_slice
= 0;
2026 cfqq
->slice_end
= 0;
2027 cfqq
->slice_dispatch
= 0;
2028 cfqq
->nr_sectors
= 0;
2030 cfq_clear_cfqq_wait_request(cfqq
);
2031 cfq_clear_cfqq_must_dispatch(cfqq
);
2032 cfq_clear_cfqq_must_alloc_slice(cfqq
);
2033 cfq_clear_cfqq_fifo_expire(cfqq
);
2034 cfq_mark_cfqq_slice_new(cfqq
);
2036 cfq_del_timer(cfqd
, cfqq
);
2039 cfqd
->active_queue
= cfqq
;
2043 * current cfqq expired its slice (or was too idle), select new one
2046 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2049 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
2051 if (cfq_cfqq_wait_request(cfqq
))
2052 cfq_del_timer(cfqd
, cfqq
);
2054 cfq_clear_cfqq_wait_request(cfqq
);
2055 cfq_clear_cfqq_wait_busy(cfqq
);
2058 * If this cfqq is shared between multiple processes, check to
2059 * make sure that those processes are still issuing I/Os within
2060 * the mean seek distance. If not, it may be time to break the
2061 * queues apart again.
2063 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
2064 cfq_mark_cfqq_split_coop(cfqq
);
2067 * store what was left of this slice, if the queue idled/timed out
2070 if (cfq_cfqq_slice_new(cfqq
))
2071 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
2073 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
2074 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
2077 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
2079 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
2080 cfq_del_cfqq_rr(cfqd
, cfqq
);
2082 cfq_resort_rr_list(cfqd
, cfqq
);
2084 if (cfqq
== cfqd
->active_queue
)
2085 cfqd
->active_queue
= NULL
;
2087 if (cfqd
->active_cic
) {
2088 put_io_context(cfqd
->active_cic
->icq
.ioc
);
2089 cfqd
->active_cic
= NULL
;
2093 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
2095 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2098 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
2102 * Get next queue for service. Unless we have a queue preemption,
2103 * we'll simply select the first cfqq in the service tree.
2105 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
2107 struct cfq_rb_root
*service_tree
=
2108 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
2109 cfqd
->serving_type
);
2111 if (!cfqd
->rq_queued
)
2114 /* There is nothing to dispatch */
2117 if (RB_EMPTY_ROOT(&service_tree
->rb
))
2119 return cfq_rb_first(service_tree
);
2122 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
2124 struct cfq_group
*cfqg
;
2125 struct cfq_queue
*cfqq
;
2127 struct cfq_rb_root
*st
;
2129 if (!cfqd
->rq_queued
)
2132 cfqg
= cfq_get_next_cfqg(cfqd
);
2136 for_each_cfqg_st(cfqg
, i
, j
, st
)
2137 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
2143 * Get and set a new active queue for service.
2145 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
2146 struct cfq_queue
*cfqq
)
2149 cfqq
= cfq_get_next_queue(cfqd
);
2151 __cfq_set_active_queue(cfqd
, cfqq
);
2155 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
2158 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
2159 return blk_rq_pos(rq
) - cfqd
->last_position
;
2161 return cfqd
->last_position
- blk_rq_pos(rq
);
2164 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2167 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
2170 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
2171 struct cfq_queue
*cur_cfqq
)
2173 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
2174 struct rb_node
*parent
, *node
;
2175 struct cfq_queue
*__cfqq
;
2176 sector_t sector
= cfqd
->last_position
;
2178 if (RB_EMPTY_ROOT(root
))
2182 * First, if we find a request starting at the end of the last
2183 * request, choose it.
2185 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
2190 * If the exact sector wasn't found, the parent of the NULL leaf
2191 * will contain the closest sector.
2193 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
2194 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2197 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
2198 node
= rb_next(&__cfqq
->p_node
);
2200 node
= rb_prev(&__cfqq
->p_node
);
2204 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
2205 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2213 * cur_cfqq - passed in so that we don't decide that the current queue is
2214 * closely cooperating with itself.
2216 * So, basically we're assuming that that cur_cfqq has dispatched at least
2217 * one request, and that cfqd->last_position reflects a position on the disk
2218 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2221 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
2222 struct cfq_queue
*cur_cfqq
)
2224 struct cfq_queue
*cfqq
;
2226 if (cfq_class_idle(cur_cfqq
))
2228 if (!cfq_cfqq_sync(cur_cfqq
))
2230 if (CFQQ_SEEKY(cur_cfqq
))
2234 * Don't search priority tree if it's the only queue in the group.
2236 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
2240 * We should notice if some of the queues are cooperating, eg
2241 * working closely on the same area of the disk. In that case,
2242 * we can group them together and don't waste time idling.
2244 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
2248 /* If new queue belongs to different cfq_group, don't choose it */
2249 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
2253 * It only makes sense to merge sync queues.
2255 if (!cfq_cfqq_sync(cfqq
))
2257 if (CFQQ_SEEKY(cfqq
))
2261 * Do not merge queues of different priority classes
2263 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
2270 * Determine whether we should enforce idle window for this queue.
2273 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2275 enum wl_prio_t prio
= cfqq_prio(cfqq
);
2276 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
2278 BUG_ON(!service_tree
);
2279 BUG_ON(!service_tree
->count
);
2281 if (!cfqd
->cfq_slice_idle
)
2284 /* We never do for idle class queues. */
2285 if (prio
== IDLE_WORKLOAD
)
2288 /* We do for queues that were marked with idle window flag. */
2289 if (cfq_cfqq_idle_window(cfqq
) &&
2290 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
2294 * Otherwise, we do only if they are the last ones
2295 * in their service tree.
2297 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
2298 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
2300 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
2301 service_tree
->count
);
2305 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2307 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2308 struct cfq_io_cq
*cic
;
2309 unsigned long sl
, group_idle
= 0;
2312 * SSD device without seek penalty, disable idling. But only do so
2313 * for devices that support queuing, otherwise we still have a problem
2314 * with sync vs async workloads.
2316 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2319 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2320 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2323 * idle is disabled, either manually or by past process history
2325 if (!cfq_should_idle(cfqd
, cfqq
)) {
2326 /* no queue idling. Check for group idling */
2327 if (cfqd
->cfq_group_idle
)
2328 group_idle
= cfqd
->cfq_group_idle
;
2334 * still active requests from this queue, don't idle
2336 if (cfqq
->dispatched
)
2340 * task has exited, don't wait
2342 cic
= cfqd
->active_cic
;
2343 if (!cic
|| !atomic_read(&cic
->icq
.ioc
->active_ref
))
2347 * If our average think time is larger than the remaining time
2348 * slice, then don't idle. This avoids overrunning the allotted
2351 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2352 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2353 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2354 cic
->ttime
.ttime_mean
);
2358 /* There are other queues in the group, don't do group idle */
2359 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2362 cfq_mark_cfqq_wait_request(cfqq
);
2365 sl
= cfqd
->cfq_group_idle
;
2367 sl
= cfqd
->cfq_slice_idle
;
2369 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2370 cfqg_stats_set_start_idle_time(cfqq
->cfqg
);
2371 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2372 group_idle
? 1 : 0);
2376 * Move request from internal lists to the request queue dispatch list.
2378 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2380 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2381 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2383 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2385 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2386 cfq_remove_request(rq
);
2388 (RQ_CFQG(rq
))->dispatched
++;
2389 elv_dispatch_sort(q
, rq
);
2391 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2392 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2393 cfqg_stats_update_dispatch(cfqq
->cfqg
, blk_rq_bytes(rq
), rq
->cmd_flags
);
2397 * return expired entry, or NULL to just start from scratch in rbtree
2399 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2401 struct request
*rq
= NULL
;
2403 if (cfq_cfqq_fifo_expire(cfqq
))
2406 cfq_mark_cfqq_fifo_expire(cfqq
);
2408 if (list_empty(&cfqq
->fifo
))
2411 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2412 if (time_before(jiffies
, rq_fifo_time(rq
)))
2415 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2420 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2422 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2424 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2426 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2430 * Must be called with the queue_lock held.
2432 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2434 int process_refs
, io_refs
;
2436 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2437 process_refs
= cfqq
->ref
- io_refs
;
2438 BUG_ON(process_refs
< 0);
2439 return process_refs
;
2442 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2444 int process_refs
, new_process_refs
;
2445 struct cfq_queue
*__cfqq
;
2448 * If there are no process references on the new_cfqq, then it is
2449 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2450 * chain may have dropped their last reference (not just their
2451 * last process reference).
2453 if (!cfqq_process_refs(new_cfqq
))
2456 /* Avoid a circular list and skip interim queue merges */
2457 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2463 process_refs
= cfqq_process_refs(cfqq
);
2464 new_process_refs
= cfqq_process_refs(new_cfqq
);
2466 * If the process for the cfqq has gone away, there is no
2467 * sense in merging the queues.
2469 if (process_refs
== 0 || new_process_refs
== 0)
2473 * Merge in the direction of the lesser amount of work.
2475 if (new_process_refs
>= process_refs
) {
2476 cfqq
->new_cfqq
= new_cfqq
;
2477 new_cfqq
->ref
+= process_refs
;
2479 new_cfqq
->new_cfqq
= cfqq
;
2480 cfqq
->ref
+= new_process_refs
;
2484 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2485 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2487 struct cfq_queue
*queue
;
2489 bool key_valid
= false;
2490 unsigned long lowest_key
= 0;
2491 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2493 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2494 /* select the one with lowest rb_key */
2495 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2497 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2498 lowest_key
= queue
->rb_key
;
2507 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2511 struct cfq_rb_root
*st
;
2512 unsigned group_slice
;
2513 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2515 /* Choose next priority. RT > BE > IDLE */
2516 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2517 cfqd
->serving_prio
= RT_WORKLOAD
;
2518 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2519 cfqd
->serving_prio
= BE_WORKLOAD
;
2521 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2522 cfqd
->workload_expires
= jiffies
+ 1;
2526 if (original_prio
!= cfqd
->serving_prio
)
2530 * For RT and BE, we have to choose also the type
2531 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2534 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2538 * check workload expiration, and that we still have other queues ready
2540 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2544 /* otherwise select new workload type */
2545 cfqd
->serving_type
=
2546 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2547 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2551 * the workload slice is computed as a fraction of target latency
2552 * proportional to the number of queues in that workload, over
2553 * all the queues in the same priority class
2555 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2557 slice
= group_slice
* count
/
2558 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2559 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2561 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2565 * Async queues are currently system wide. Just taking
2566 * proportion of queues with-in same group will lead to higher
2567 * async ratio system wide as generally root group is going
2568 * to have higher weight. A more accurate thing would be to
2569 * calculate system wide asnc/sync ratio.
2571 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2572 tmp
= tmp
/cfqd
->busy_queues
;
2573 slice
= min_t(unsigned, slice
, tmp
);
2575 /* async workload slice is scaled down according to
2576 * the sync/async slice ratio. */
2577 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2579 /* sync workload slice is at least 2 * cfq_slice_idle */
2580 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2582 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2583 cfq_log(cfqd
, "workload slice:%d", slice
);
2584 cfqd
->workload_expires
= jiffies
+ slice
;
2587 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2589 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2590 struct cfq_group
*cfqg
;
2592 if (RB_EMPTY_ROOT(&st
->rb
))
2594 cfqg
= cfq_rb_first_group(st
);
2595 update_min_vdisktime(st
);
2599 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2601 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2603 cfqd
->serving_group
= cfqg
;
2605 /* Restore the workload type data */
2606 if (cfqg
->saved_workload_slice
) {
2607 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2608 cfqd
->serving_type
= cfqg
->saved_workload
;
2609 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2611 cfqd
->workload_expires
= jiffies
- 1;
2613 choose_service_tree(cfqd
, cfqg
);
2617 * Select a queue for service. If we have a current active queue,
2618 * check whether to continue servicing it, or retrieve and set a new one.
2620 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2622 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2624 cfqq
= cfqd
->active_queue
;
2628 if (!cfqd
->rq_queued
)
2632 * We were waiting for group to get backlogged. Expire the queue
2634 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2638 * The active queue has run out of time, expire it and select new.
2640 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2642 * If slice had not expired at the completion of last request
2643 * we might not have turned on wait_busy flag. Don't expire
2644 * the queue yet. Allow the group to get backlogged.
2646 * The very fact that we have used the slice, that means we
2647 * have been idling all along on this queue and it should be
2648 * ok to wait for this request to complete.
2650 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2651 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2655 goto check_group_idle
;
2659 * The active queue has requests and isn't expired, allow it to
2662 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2666 * If another queue has a request waiting within our mean seek
2667 * distance, let it run. The expire code will check for close
2668 * cooperators and put the close queue at the front of the service
2669 * tree. If possible, merge the expiring queue with the new cfqq.
2671 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2673 if (!cfqq
->new_cfqq
)
2674 cfq_setup_merge(cfqq
, new_cfqq
);
2679 * No requests pending. If the active queue still has requests in
2680 * flight or is idling for a new request, allow either of these
2681 * conditions to happen (or time out) before selecting a new queue.
2683 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2689 * This is a deep seek queue, but the device is much faster than
2690 * the queue can deliver, don't idle
2692 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2693 (cfq_cfqq_slice_new(cfqq
) ||
2694 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2695 cfq_clear_cfqq_deep(cfqq
);
2696 cfq_clear_cfqq_idle_window(cfqq
);
2699 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2705 * If group idle is enabled and there are requests dispatched from
2706 * this group, wait for requests to complete.
2709 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2710 cfqq
->cfqg
->dispatched
&&
2711 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2717 cfq_slice_expired(cfqd
, 0);
2720 * Current queue expired. Check if we have to switch to a new
2724 cfq_choose_cfqg(cfqd
);
2726 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2731 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2735 while (cfqq
->next_rq
) {
2736 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2740 BUG_ON(!list_empty(&cfqq
->fifo
));
2742 /* By default cfqq is not expired if it is empty. Do it explicitly */
2743 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2748 * Drain our current requests. Used for barriers and when switching
2749 * io schedulers on-the-fly.
2751 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2753 struct cfq_queue
*cfqq
;
2756 /* Expire the timeslice of the current active queue first */
2757 cfq_slice_expired(cfqd
, 0);
2758 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2759 __cfq_set_active_queue(cfqd
, cfqq
);
2760 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2763 BUG_ON(cfqd
->busy_queues
);
2765 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2769 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2770 struct cfq_queue
*cfqq
)
2772 /* the queue hasn't finished any request, can't estimate */
2773 if (cfq_cfqq_slice_new(cfqq
))
2775 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2782 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2784 unsigned int max_dispatch
;
2787 * Drain async requests before we start sync IO
2789 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2793 * If this is an async queue and we have sync IO in flight, let it wait
2795 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2798 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2799 if (cfq_class_idle(cfqq
))
2803 * Does this cfqq already have too much IO in flight?
2805 if (cfqq
->dispatched
>= max_dispatch
) {
2806 bool promote_sync
= false;
2808 * idle queue must always only have a single IO in flight
2810 if (cfq_class_idle(cfqq
))
2814 * If there is only one sync queue
2815 * we can ignore async queue here and give the sync
2816 * queue no dispatch limit. The reason is a sync queue can
2817 * preempt async queue, limiting the sync queue doesn't make
2818 * sense. This is useful for aiostress test.
2820 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2821 promote_sync
= true;
2824 * We have other queues, don't allow more IO from this one
2826 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2831 * Sole queue user, no limit
2833 if (cfqd
->busy_queues
== 1 || promote_sync
)
2837 * Normally we start throttling cfqq when cfq_quantum/2
2838 * requests have been dispatched. But we can drive
2839 * deeper queue depths at the beginning of slice
2840 * subjected to upper limit of cfq_quantum.
2842 max_dispatch
= cfqd
->cfq_quantum
;
2846 * Async queues must wait a bit before being allowed dispatch.
2847 * We also ramp up the dispatch depth gradually for async IO,
2848 * based on the last sync IO we serviced
2850 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2851 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2854 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2855 if (!depth
&& !cfqq
->dispatched
)
2857 if (depth
< max_dispatch
)
2858 max_dispatch
= depth
;
2862 * If we're below the current max, allow a dispatch
2864 return cfqq
->dispatched
< max_dispatch
;
2868 * Dispatch a request from cfqq, moving them to the request queue
2871 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2875 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2877 if (!cfq_may_dispatch(cfqd
, cfqq
))
2881 * follow expired path, else get first next available
2883 rq
= cfq_check_fifo(cfqq
);
2888 * insert request into driver dispatch list
2890 cfq_dispatch_insert(cfqd
->queue
, rq
);
2892 if (!cfqd
->active_cic
) {
2893 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
2895 atomic_long_inc(&cic
->icq
.ioc
->refcount
);
2896 cfqd
->active_cic
= cic
;
2903 * Find the cfqq that we need to service and move a request from that to the
2906 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2908 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2909 struct cfq_queue
*cfqq
;
2911 if (!cfqd
->busy_queues
)
2914 if (unlikely(force
))
2915 return cfq_forced_dispatch(cfqd
);
2917 cfqq
= cfq_select_queue(cfqd
);
2922 * Dispatch a request from this cfqq, if it is allowed
2924 if (!cfq_dispatch_request(cfqd
, cfqq
))
2927 cfqq
->slice_dispatch
++;
2928 cfq_clear_cfqq_must_dispatch(cfqq
);
2931 * expire an async queue immediately if it has used up its slice. idle
2932 * queue always expire after 1 dispatch round.
2934 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2935 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2936 cfq_class_idle(cfqq
))) {
2937 cfqq
->slice_end
= jiffies
+ 1;
2938 cfq_slice_expired(cfqd
, 0);
2941 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2946 * task holds one reference to the queue, dropped when task exits. each rq
2947 * in-flight on this queue also holds a reference, dropped when rq is freed.
2949 * Each cfq queue took a reference on the parent group. Drop it now.
2950 * queue lock must be held here.
2952 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2954 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2955 struct cfq_group
*cfqg
;
2957 BUG_ON(cfqq
->ref
<= 0);
2963 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2964 BUG_ON(rb_first(&cfqq
->sort_list
));
2965 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2968 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2969 __cfq_slice_expired(cfqd
, cfqq
, 0);
2970 cfq_schedule_dispatch(cfqd
);
2973 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2974 kmem_cache_free(cfq_pool
, cfqq
);
2978 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2980 struct cfq_queue
*__cfqq
, *next
;
2983 * If this queue was scheduled to merge with another queue, be
2984 * sure to drop the reference taken on that queue (and others in
2985 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2987 __cfqq
= cfqq
->new_cfqq
;
2989 if (__cfqq
== cfqq
) {
2990 WARN(1, "cfqq->new_cfqq loop detected\n");
2993 next
= __cfqq
->new_cfqq
;
2994 cfq_put_queue(__cfqq
);
2999 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3001 if (unlikely(cfqq
== cfqd
->active_queue
)) {
3002 __cfq_slice_expired(cfqd
, cfqq
, 0);
3003 cfq_schedule_dispatch(cfqd
);
3006 cfq_put_cooperator(cfqq
);
3008 cfq_put_queue(cfqq
);
3011 static void cfq_init_icq(struct io_cq
*icq
)
3013 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3015 cic
->ttime
.last_end_request
= jiffies
;
3018 static void cfq_exit_icq(struct io_cq
*icq
)
3020 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3021 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3023 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
3024 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
3025 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
3028 if (cic
->cfqq
[BLK_RW_SYNC
]) {
3029 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
3030 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
3034 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct cfq_io_cq
*cic
)
3036 struct task_struct
*tsk
= current
;
3039 if (!cfq_cfqq_prio_changed(cfqq
))
3042 ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3043 switch (ioprio_class
) {
3045 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
3046 case IOPRIO_CLASS_NONE
:
3048 * no prio set, inherit CPU scheduling settings
3050 cfqq
->ioprio
= task_nice_ioprio(tsk
);
3051 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
3053 case IOPRIO_CLASS_RT
:
3054 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3055 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
3057 case IOPRIO_CLASS_BE
:
3058 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3059 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3061 case IOPRIO_CLASS_IDLE
:
3062 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
3064 cfq_clear_cfqq_idle_window(cfqq
);
3069 * keep track of original prio settings in case we have to temporarily
3070 * elevate the priority of this queue
3072 cfqq
->org_ioprio
= cfqq
->ioprio
;
3073 cfq_clear_cfqq_prio_changed(cfqq
);
3076 static void check_ioprio_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3078 int ioprio
= cic
->icq
.ioc
->ioprio
;
3079 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3080 struct cfq_queue
*cfqq
;
3083 * Check whether ioprio has changed. The condition may trigger
3084 * spuriously on a newly created cic but there's no harm.
3086 if (unlikely(!cfqd
) || likely(cic
->ioprio
== ioprio
))
3089 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
3091 struct cfq_queue
*new_cfqq
;
3092 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
, bio
,
3095 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
3096 cfq_put_queue(cfqq
);
3100 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
3102 cfq_mark_cfqq_prio_changed(cfqq
);
3104 cic
->ioprio
= ioprio
;
3107 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3108 pid_t pid
, bool is_sync
)
3110 RB_CLEAR_NODE(&cfqq
->rb_node
);
3111 RB_CLEAR_NODE(&cfqq
->p_node
);
3112 INIT_LIST_HEAD(&cfqq
->fifo
);
3117 cfq_mark_cfqq_prio_changed(cfqq
);
3120 if (!cfq_class_idle(cfqq
))
3121 cfq_mark_cfqq_idle_window(cfqq
);
3122 cfq_mark_cfqq_sync(cfqq
);
3127 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3128 static void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3130 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3131 struct cfq_queue
*sync_cfqq
;
3135 id
= bio_blkio_cgroup(bio
)->id
;
3139 * Check whether blkcg has changed. The condition may trigger
3140 * spuriously on a newly created cic but there's no harm.
3142 if (unlikely(!cfqd
) || likely(cic
->blkcg_id
== id
))
3145 sync_cfqq
= cic_to_cfqq(cic
, 1);
3148 * Drop reference to sync queue. A new sync queue will be
3149 * assigned in new group upon arrival of a fresh request.
3151 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
3152 cic_set_cfqq(cic
, NULL
, 1);
3153 cfq_put_queue(sync_cfqq
);
3159 static inline void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
) { }
3160 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3162 static struct cfq_queue
*
3163 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3164 struct bio
*bio
, gfp_t gfp_mask
)
3166 struct blkio_cgroup
*blkcg
;
3167 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
3168 struct cfq_group
*cfqg
;
3173 blkcg
= bio_blkio_cgroup(bio
);
3174 cfqg
= cfq_lookup_create_cfqg(cfqd
, blkcg
);
3175 cfqq
= cic_to_cfqq(cic
, is_sync
);
3178 * Always try a new alloc if we fell back to the OOM cfqq
3179 * originally, since it should just be a temporary situation.
3181 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3186 } else if (gfp_mask
& __GFP_WAIT
) {
3188 spin_unlock_irq(cfqd
->queue
->queue_lock
);
3189 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
3190 gfp_mask
| __GFP_ZERO
,
3192 spin_lock_irq(cfqd
->queue
->queue_lock
);
3196 cfqq
= kmem_cache_alloc_node(cfq_pool
,
3197 gfp_mask
| __GFP_ZERO
,
3202 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
3203 cfq_init_prio_data(cfqq
, cic
);
3204 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
3205 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
3207 cfqq
= &cfqd
->oom_cfqq
;
3211 kmem_cache_free(cfq_pool
, new_cfqq
);
3217 static struct cfq_queue
**
3218 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
3220 switch (ioprio_class
) {
3221 case IOPRIO_CLASS_RT
:
3222 return &cfqd
->async_cfqq
[0][ioprio
];
3223 case IOPRIO_CLASS_NONE
:
3224 ioprio
= IOPRIO_NORM
;
3226 case IOPRIO_CLASS_BE
:
3227 return &cfqd
->async_cfqq
[1][ioprio
];
3228 case IOPRIO_CLASS_IDLE
:
3229 return &cfqd
->async_idle_cfqq
;
3235 static struct cfq_queue
*
3236 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3237 struct bio
*bio
, gfp_t gfp_mask
)
3239 const int ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3240 const int ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3241 struct cfq_queue
**async_cfqq
= NULL
;
3242 struct cfq_queue
*cfqq
= NULL
;
3245 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
3250 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3253 * pin the queue now that it's allocated, scheduler exit will prune it
3255 if (!is_sync
&& !(*async_cfqq
)) {
3265 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3267 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3268 elapsed
= min(elapsed
, 2UL * slice_idle
);
3270 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3271 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3272 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3276 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3277 struct cfq_io_cq
*cic
)
3279 if (cfq_cfqq_sync(cfqq
)) {
3280 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3281 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3282 cfqd
->cfq_slice_idle
);
3284 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3285 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3290 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3294 sector_t n_sec
= blk_rq_sectors(rq
);
3295 if (cfqq
->last_request_pos
) {
3296 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3297 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3299 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3302 cfqq
->seek_history
<<= 1;
3303 if (blk_queue_nonrot(cfqd
->queue
))
3304 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3306 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3310 * Disable idle window if the process thinks too long or seeks so much that
3314 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3315 struct cfq_io_cq
*cic
)
3317 int old_idle
, enable_idle
;
3320 * Don't idle for async or idle io prio class
3322 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3325 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3327 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3328 cfq_mark_cfqq_deep(cfqq
);
3330 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3332 else if (!atomic_read(&cic
->icq
.ioc
->active_ref
) ||
3333 !cfqd
->cfq_slice_idle
||
3334 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3336 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3337 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3343 if (old_idle
!= enable_idle
) {
3344 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3346 cfq_mark_cfqq_idle_window(cfqq
);
3348 cfq_clear_cfqq_idle_window(cfqq
);
3353 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3354 * no or if we aren't sure, a 1 will cause a preempt.
3357 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3360 struct cfq_queue
*cfqq
;
3362 cfqq
= cfqd
->active_queue
;
3366 if (cfq_class_idle(new_cfqq
))
3369 if (cfq_class_idle(cfqq
))
3373 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3375 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3379 * if the new request is sync, but the currently running queue is
3380 * not, let the sync request have priority.
3382 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3385 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3388 if (cfq_slice_used(cfqq
))
3391 /* Allow preemption only if we are idling on sync-noidle tree */
3392 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3393 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3394 new_cfqq
->service_tree
->count
== 2 &&
3395 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3399 * So both queues are sync. Let the new request get disk time if
3400 * it's a metadata request and the current queue is doing regular IO.
3402 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3406 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3408 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3411 /* An idle queue should not be idle now for some reason */
3412 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3415 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3419 * if this request is as-good as one we would expect from the
3420 * current cfqq, let it preempt
3422 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3429 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3430 * let it have half of its nominal slice.
3432 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3434 enum wl_type_t old_type
= cfqq_type(cfqd
->active_queue
);
3436 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3437 cfq_slice_expired(cfqd
, 1);
3440 * workload type is changed, don't save slice, otherwise preempt
3443 if (old_type
!= cfqq_type(cfqq
))
3444 cfqq
->cfqg
->saved_workload_slice
= 0;
3447 * Put the new queue at the front of the of the current list,
3448 * so we know that it will be selected next.
3450 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3452 cfq_service_tree_add(cfqd
, cfqq
, 1);
3454 cfqq
->slice_end
= 0;
3455 cfq_mark_cfqq_slice_new(cfqq
);
3459 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3460 * something we should do about it
3463 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3466 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3469 if (rq
->cmd_flags
& REQ_PRIO
)
3470 cfqq
->prio_pending
++;
3472 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3473 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3474 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3476 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3478 if (cfqq
== cfqd
->active_queue
) {
3480 * Remember that we saw a request from this process, but
3481 * don't start queuing just yet. Otherwise we risk seeing lots
3482 * of tiny requests, because we disrupt the normal plugging
3483 * and merging. If the request is already larger than a single
3484 * page, let it rip immediately. For that case we assume that
3485 * merging is already done. Ditto for a busy system that
3486 * has other work pending, don't risk delaying until the
3487 * idle timer unplug to continue working.
3489 if (cfq_cfqq_wait_request(cfqq
)) {
3490 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3491 cfqd
->busy_queues
> 1) {
3492 cfq_del_timer(cfqd
, cfqq
);
3493 cfq_clear_cfqq_wait_request(cfqq
);
3494 __blk_run_queue(cfqd
->queue
);
3496 cfqg_stats_update_idle_time(cfqq
->cfqg
);
3497 cfq_mark_cfqq_must_dispatch(cfqq
);
3500 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3502 * not the active queue - expire current slice if it is
3503 * idle and has expired it's mean thinktime or this new queue
3504 * has some old slice time left and is of higher priority or
3505 * this new queue is RT and the current one is BE
3507 cfq_preempt_queue(cfqd
, cfqq
);
3508 __blk_run_queue(cfqd
->queue
);
3512 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3514 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3515 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3517 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3518 cfq_init_prio_data(cfqq
, RQ_CIC(rq
));
3520 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3521 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3523 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqd
->serving_group
,
3525 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3529 * Update hw_tag based on peak queue depth over 50 samples under
3532 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3534 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3536 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3537 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3539 if (cfqd
->hw_tag
== 1)
3542 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3543 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3547 * If active queue hasn't enough requests and can idle, cfq might not
3548 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3551 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3552 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3553 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3556 if (cfqd
->hw_tag_samples
++ < 50)
3559 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3565 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3567 struct cfq_io_cq
*cic
= cfqd
->active_cic
;
3569 /* If the queue already has requests, don't wait */
3570 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3573 /* If there are other queues in the group, don't wait */
3574 if (cfqq
->cfqg
->nr_cfqq
> 1)
3577 /* the only queue in the group, but think time is big */
3578 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3581 if (cfq_slice_used(cfqq
))
3584 /* if slice left is less than think time, wait busy */
3585 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3586 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3590 * If think times is less than a jiffy than ttime_mean=0 and above
3591 * will not be true. It might happen that slice has not expired yet
3592 * but will expire soon (4-5 ns) during select_queue(). To cover the
3593 * case where think time is less than a jiffy, mark the queue wait
3594 * busy if only 1 jiffy is left in the slice.
3596 if (cfqq
->slice_end
- jiffies
== 1)
3602 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3604 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3605 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3606 const int sync
= rq_is_sync(rq
);
3610 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3611 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3613 cfq_update_hw_tag(cfqd
);
3615 WARN_ON(!cfqd
->rq_in_driver
);
3616 WARN_ON(!cfqq
->dispatched
);
3617 cfqd
->rq_in_driver
--;
3619 (RQ_CFQG(rq
))->dispatched
--;
3620 cfqg_stats_update_completion(cfqq
->cfqg
, rq_start_time_ns(rq
),
3621 rq_io_start_time_ns(rq
), rq
->cmd_flags
);
3623 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3626 struct cfq_rb_root
*service_tree
;
3628 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3630 if (cfq_cfqq_on_rr(cfqq
))
3631 service_tree
= cfqq
->service_tree
;
3633 service_tree
= service_tree_for(cfqq
->cfqg
,
3634 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3635 service_tree
->ttime
.last_end_request
= now
;
3636 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3637 cfqd
->last_delayed_sync
= now
;
3640 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3641 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3645 * If this is the active queue, check if it needs to be expired,
3646 * or if we want to idle in case it has no pending requests.
3648 if (cfqd
->active_queue
== cfqq
) {
3649 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3651 if (cfq_cfqq_slice_new(cfqq
)) {
3652 cfq_set_prio_slice(cfqd
, cfqq
);
3653 cfq_clear_cfqq_slice_new(cfqq
);
3657 * Should we wait for next request to come in before we expire
3660 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3661 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3662 if (!cfqd
->cfq_slice_idle
)
3663 extend_sl
= cfqd
->cfq_group_idle
;
3664 cfqq
->slice_end
= jiffies
+ extend_sl
;
3665 cfq_mark_cfqq_wait_busy(cfqq
);
3666 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3670 * Idling is not enabled on:
3672 * - idle-priority queues
3674 * - queues with still some requests queued
3675 * - when there is a close cooperator
3677 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3678 cfq_slice_expired(cfqd
, 1);
3679 else if (sync
&& cfqq_empty
&&
3680 !cfq_close_cooperator(cfqd
, cfqq
)) {
3681 cfq_arm_slice_timer(cfqd
);
3685 if (!cfqd
->rq_in_driver
)
3686 cfq_schedule_dispatch(cfqd
);
3689 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3691 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3692 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3693 return ELV_MQUEUE_MUST
;
3696 return ELV_MQUEUE_MAY
;
3699 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3701 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3702 struct task_struct
*tsk
= current
;
3703 struct cfq_io_cq
*cic
;
3704 struct cfq_queue
*cfqq
;
3707 * don't force setup of a queue from here, as a call to may_queue
3708 * does not necessarily imply that a request actually will be queued.
3709 * so just lookup a possibly existing queue, or return 'may queue'
3712 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3714 return ELV_MQUEUE_MAY
;
3716 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3718 cfq_init_prio_data(cfqq
, cic
);
3720 return __cfq_may_queue(cfqq
);
3723 return ELV_MQUEUE_MAY
;
3727 * queue lock held here
3729 static void cfq_put_request(struct request
*rq
)
3731 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3734 const int rw
= rq_data_dir(rq
);
3736 BUG_ON(!cfqq
->allocated
[rw
]);
3737 cfqq
->allocated
[rw
]--;
3739 /* Put down rq reference on cfqg */
3740 cfqg_put(RQ_CFQG(rq
));
3741 rq
->elv
.priv
[0] = NULL
;
3742 rq
->elv
.priv
[1] = NULL
;
3744 cfq_put_queue(cfqq
);
3748 static struct cfq_queue
*
3749 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_cq
*cic
,
3750 struct cfq_queue
*cfqq
)
3752 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3753 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3754 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3755 cfq_put_queue(cfqq
);
3756 return cic_to_cfqq(cic
, 1);
3760 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3761 * was the last process referring to said cfqq.
3763 static struct cfq_queue
*
3764 split_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
)
3766 if (cfqq_process_refs(cfqq
) == 1) {
3767 cfqq
->pid
= current
->pid
;
3768 cfq_clear_cfqq_coop(cfqq
);
3769 cfq_clear_cfqq_split_coop(cfqq
);
3773 cic_set_cfqq(cic
, NULL
, 1);
3775 cfq_put_cooperator(cfqq
);
3777 cfq_put_queue(cfqq
);
3781 * Allocate cfq data structures associated with this request.
3784 cfq_set_request(struct request_queue
*q
, struct request
*rq
, struct bio
*bio
,
3787 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3788 struct cfq_io_cq
*cic
= icq_to_cic(rq
->elv
.icq
);
3789 const int rw
= rq_data_dir(rq
);
3790 const bool is_sync
= rq_is_sync(rq
);
3791 struct cfq_queue
*cfqq
;
3793 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3795 spin_lock_irq(q
->queue_lock
);
3797 check_ioprio_changed(cic
, bio
);
3798 check_blkcg_changed(cic
, bio
);
3800 cfqq
= cic_to_cfqq(cic
, is_sync
);
3801 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3802 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3803 cic_set_cfqq(cic
, cfqq
, is_sync
);
3806 * If the queue was seeky for too long, break it apart.
3808 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3809 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3810 cfqq
= split_cfqq(cic
, cfqq
);
3816 * Check to see if this queue is scheduled to merge with
3817 * another, closely cooperating queue. The merging of
3818 * queues happens here as it must be done in process context.
3819 * The reference on new_cfqq was taken in merge_cfqqs.
3822 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3825 cfqq
->allocated
[rw
]++;
3828 cfqg_get(cfqq
->cfqg
);
3829 rq
->elv
.priv
[0] = cfqq
;
3830 rq
->elv
.priv
[1] = cfqq
->cfqg
;
3831 spin_unlock_irq(q
->queue_lock
);
3835 static void cfq_kick_queue(struct work_struct
*work
)
3837 struct cfq_data
*cfqd
=
3838 container_of(work
, struct cfq_data
, unplug_work
);
3839 struct request_queue
*q
= cfqd
->queue
;
3841 spin_lock_irq(q
->queue_lock
);
3842 __blk_run_queue(cfqd
->queue
);
3843 spin_unlock_irq(q
->queue_lock
);
3847 * Timer running if the active_queue is currently idling inside its time slice
3849 static void cfq_idle_slice_timer(unsigned long data
)
3851 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3852 struct cfq_queue
*cfqq
;
3853 unsigned long flags
;
3856 cfq_log(cfqd
, "idle timer fired");
3858 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3860 cfqq
= cfqd
->active_queue
;
3865 * We saw a request before the queue expired, let it through
3867 if (cfq_cfqq_must_dispatch(cfqq
))
3873 if (cfq_slice_used(cfqq
))
3877 * only expire and reinvoke request handler, if there are
3878 * other queues with pending requests
3880 if (!cfqd
->busy_queues
)
3884 * not expired and it has a request pending, let it dispatch
3886 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3890 * Queue depth flag is reset only when the idle didn't succeed
3892 cfq_clear_cfqq_deep(cfqq
);
3895 cfq_slice_expired(cfqd
, timed_out
);
3897 cfq_schedule_dispatch(cfqd
);
3899 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3902 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3904 del_timer_sync(&cfqd
->idle_slice_timer
);
3905 cancel_work_sync(&cfqd
->unplug_work
);
3908 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3912 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3913 if (cfqd
->async_cfqq
[0][i
])
3914 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3915 if (cfqd
->async_cfqq
[1][i
])
3916 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3919 if (cfqd
->async_idle_cfqq
)
3920 cfq_put_queue(cfqd
->async_idle_cfqq
);
3923 static void cfq_exit_queue(struct elevator_queue
*e
)
3925 struct cfq_data
*cfqd
= e
->elevator_data
;
3926 struct request_queue
*q
= cfqd
->queue
;
3928 cfq_shutdown_timer_wq(cfqd
);
3930 spin_lock_irq(q
->queue_lock
);
3932 if (cfqd
->active_queue
)
3933 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3935 cfq_put_async_queues(cfqd
);
3937 spin_unlock_irq(q
->queue_lock
);
3939 cfq_shutdown_timer_wq(cfqd
);
3941 #ifndef CONFIG_CFQ_GROUP_IOSCHED
3942 kfree(cfqd
->root_group
);
3944 update_root_blkg_pd(q
, BLKIO_POLICY_PROP
);
3948 static int cfq_init_queue(struct request_queue
*q
)
3950 struct cfq_data
*cfqd
;
3951 struct blkio_group
*blkg __maybe_unused
;
3954 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3959 q
->elevator
->elevator_data
= cfqd
;
3961 /* Init root service tree */
3962 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3964 /* Init root group and prefer root group over other groups by default */
3965 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3967 spin_lock_irq(q
->queue_lock
);
3969 blkg
= blkg_lookup_create(&blkio_root_cgroup
, q
, true);
3971 cfqd
->root_group
= blkg_to_cfqg(blkg
);
3973 spin_unlock_irq(q
->queue_lock
);
3976 cfqd
->root_group
= kzalloc_node(sizeof(*cfqd
->root_group
),
3977 GFP_KERNEL
, cfqd
->queue
->node
);
3978 if (cfqd
->root_group
)
3979 cfq_init_cfqg_base(cfqd
->root_group
);
3981 if (!cfqd
->root_group
) {
3986 cfqd
->root_group
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3989 * Not strictly needed (since RB_ROOT just clears the node and we
3990 * zeroed cfqd on alloc), but better be safe in case someone decides
3991 * to add magic to the rb code
3993 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3994 cfqd
->prio_trees
[i
] = RB_ROOT
;
3997 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3998 * Grab a permanent reference to it, so that the normal code flow
3999 * will not attempt to free it. oom_cfqq is linked to root_group
4000 * but shouldn't hold a reference as it'll never be unlinked. Lose
4001 * the reference from linking right away.
4003 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
4004 cfqd
->oom_cfqq
.ref
++;
4006 spin_lock_irq(q
->queue_lock
);
4007 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, cfqd
->root_group
);
4008 cfqg_put(cfqd
->root_group
);
4009 spin_unlock_irq(q
->queue_lock
);
4011 init_timer(&cfqd
->idle_slice_timer
);
4012 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
4013 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
4015 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
4017 cfqd
->cfq_quantum
= cfq_quantum
;
4018 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
4019 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
4020 cfqd
->cfq_back_max
= cfq_back_max
;
4021 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
4022 cfqd
->cfq_slice
[0] = cfq_slice_async
;
4023 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
4024 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
4025 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
4026 cfqd
->cfq_group_idle
= cfq_group_idle
;
4027 cfqd
->cfq_latency
= 1;
4030 * we optimistically start assuming sync ops weren't delayed in last
4031 * second, in order to have larger depth for async operations.
4033 cfqd
->last_delayed_sync
= jiffies
- HZ
;
4038 * sysfs parts below -->
4041 cfq_var_show(unsigned int var
, char *page
)
4043 return sprintf(page
, "%d\n", var
);
4047 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4049 char *p
= (char *) page
;
4051 *var
= simple_strtoul(p
, &p
, 10);
4055 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4056 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4058 struct cfq_data *cfqd = e->elevator_data; \
4059 unsigned int __data = __VAR; \
4061 __data = jiffies_to_msecs(__data); \
4062 return cfq_var_show(__data, (page)); \
4064 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4065 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4066 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4067 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4068 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4069 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4070 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4071 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4072 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4073 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4074 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4075 #undef SHOW_FUNCTION
4077 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4078 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4080 struct cfq_data *cfqd = e->elevator_data; \
4081 unsigned int __data; \
4082 int ret = cfq_var_store(&__data, (page), count); \
4083 if (__data < (MIN)) \
4085 else if (__data > (MAX)) \
4088 *(__PTR) = msecs_to_jiffies(__data); \
4090 *(__PTR) = __data; \
4093 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4094 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4096 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4098 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4099 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4101 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4102 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4103 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4104 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4105 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4107 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4108 #undef STORE_FUNCTION
4110 #define CFQ_ATTR(name) \
4111 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4113 static struct elv_fs_entry cfq_attrs
[] = {
4115 CFQ_ATTR(fifo_expire_sync
),
4116 CFQ_ATTR(fifo_expire_async
),
4117 CFQ_ATTR(back_seek_max
),
4118 CFQ_ATTR(back_seek_penalty
),
4119 CFQ_ATTR(slice_sync
),
4120 CFQ_ATTR(slice_async
),
4121 CFQ_ATTR(slice_async_rq
),
4122 CFQ_ATTR(slice_idle
),
4123 CFQ_ATTR(group_idle
),
4124 CFQ_ATTR(low_latency
),
4128 static struct elevator_type iosched_cfq
= {
4130 .elevator_merge_fn
= cfq_merge
,
4131 .elevator_merged_fn
= cfq_merged_request
,
4132 .elevator_merge_req_fn
= cfq_merged_requests
,
4133 .elevator_allow_merge_fn
= cfq_allow_merge
,
4134 .elevator_bio_merged_fn
= cfq_bio_merged
,
4135 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4136 .elevator_add_req_fn
= cfq_insert_request
,
4137 .elevator_activate_req_fn
= cfq_activate_request
,
4138 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4139 .elevator_completed_req_fn
= cfq_completed_request
,
4140 .elevator_former_req_fn
= elv_rb_former_request
,
4141 .elevator_latter_req_fn
= elv_rb_latter_request
,
4142 .elevator_init_icq_fn
= cfq_init_icq
,
4143 .elevator_exit_icq_fn
= cfq_exit_icq
,
4144 .elevator_set_req_fn
= cfq_set_request
,
4145 .elevator_put_req_fn
= cfq_put_request
,
4146 .elevator_may_queue_fn
= cfq_may_queue
,
4147 .elevator_init_fn
= cfq_init_queue
,
4148 .elevator_exit_fn
= cfq_exit_queue
,
4150 .icq_size
= sizeof(struct cfq_io_cq
),
4151 .icq_align
= __alignof__(struct cfq_io_cq
),
4152 .elevator_attrs
= cfq_attrs
,
4153 .elevator_name
= "cfq",
4154 .elevator_owner
= THIS_MODULE
,
4157 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4158 static struct blkio_policy_type blkio_policy_cfq
= {
4160 .blkio_init_group_fn
= cfq_init_blkio_group
,
4161 .blkio_reset_group_stats_fn
= cfqg_stats_reset
,
4163 .plid
= BLKIO_POLICY_PROP
,
4164 .pdata_size
= sizeof(struct cfq_group
),
4165 .cftypes
= cfq_blkcg_files
,
4169 static int __init
cfq_init(void)
4174 * could be 0 on HZ < 1000 setups
4176 if (!cfq_slice_async
)
4177 cfq_slice_async
= 1;
4178 if (!cfq_slice_idle
)
4181 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4182 if (!cfq_group_idle
)
4187 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
4191 ret
= elv_register(&iosched_cfq
);
4193 kmem_cache_destroy(cfq_pool
);
4197 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4198 blkio_policy_register(&blkio_policy_cfq
);
4203 static void __exit
cfq_exit(void)
4205 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4206 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");