2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
18 #include "blk-cgroup.h"
23 /* max queue in one round of service */
24 static const int cfq_quantum
= 8;
25 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max
= 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty
= 2;
30 static const int cfq_slice_sync
= HZ
/ 10;
31 static int cfq_slice_async
= HZ
/ 25;
32 static const int cfq_slice_async_rq
= 2;
33 static int cfq_slice_idle
= HZ
/ 125;
34 static int cfq_group_idle
= HZ
/ 125;
35 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
36 static const int cfq_hist_divisor
= 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache
*cfq_pool
;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
71 unsigned long last_end_request
;
73 unsigned long ttime_total
;
74 unsigned long ttime_samples
;
75 unsigned long ttime_mean
;
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight
;
90 struct cfq_ttime ttime
;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
96 * Per process-grouping structure
101 /* various state flags, see below */
103 /* parent cfq_data */
104 struct cfq_data
*cfqd
;
105 /* service_tree member */
106 struct rb_node rb_node
;
107 /* service_tree key */
108 unsigned long rb_key
;
109 /* prio tree member */
110 struct rb_node p_node
;
111 /* prio tree root we belong to, if any */
112 struct rb_root
*p_root
;
113 /* sorted list of pending requests */
114 struct rb_root sort_list
;
115 /* if fifo isn't expired, next request to serve */
116 struct request
*next_rq
;
117 /* requests queued in sort_list */
119 /* currently allocated requests */
121 /* fifo list of requests in sort_list */
122 struct list_head fifo
;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start
;
126 unsigned int allocated_slice
;
127 unsigned int slice_dispatch
;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start
;
130 unsigned long slice_end
;
133 /* pending priority requests */
135 /* number of requests that are on the dispatch list or inside driver */
138 /* io prio of this group */
139 unsigned short ioprio
, org_ioprio
;
140 unsigned short ioprio_class
;
145 sector_t last_request_pos
;
147 struct cfq_rb_root
*service_tree
;
148 struct cfq_queue
*new_cfqq
;
149 struct cfq_group
*cfqg
;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors
;
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
166 * Second index in the service_trees.
170 SYNC_NOIDLE_WORKLOAD
= 1,
175 #ifdef CONFIG_CFQ_GROUP_IOSCHED
176 /* total bytes transferred */
177 struct blkg_rwstat service_bytes
;
178 /* total IOs serviced, post merge */
179 struct blkg_rwstat serviced
;
180 /* number of ios merged */
181 struct blkg_rwstat merged
;
182 /* total time spent on device in ns, may not be accurate w/ queueing */
183 struct blkg_rwstat service_time
;
184 /* total time spent waiting in scheduler queue in ns */
185 struct blkg_rwstat wait_time
;
186 /* number of IOs queued up */
187 struct blkg_rwstat queued
;
188 /* total sectors transferred */
189 struct blkg_stat sectors
;
190 /* total disk time and nr sectors dispatched by this group */
191 struct blkg_stat time
;
192 #ifdef CONFIG_DEBUG_BLK_CGROUP
193 /* time not charged to this cgroup */
194 struct blkg_stat unaccounted_time
;
195 /* sum of number of ios queued across all samples */
196 struct blkg_stat avg_queue_size_sum
;
197 /* count of samples taken for average */
198 struct blkg_stat avg_queue_size_samples
;
199 /* how many times this group has been removed from service tree */
200 struct blkg_stat dequeue
;
201 /* total time spent waiting for it to be assigned a timeslice. */
202 struct blkg_stat group_wait_time
;
203 /* time spent idling for this blkcg_gq */
204 struct blkg_stat idle_time
;
205 /* total time with empty current active q with other requests queued */
206 struct blkg_stat empty_time
;
207 /* fields after this shouldn't be cleared on stat reset */
208 uint64_t start_group_wait_time
;
209 uint64_t start_idle_time
;
210 uint64_t start_empty_time
;
212 #endif /* CONFIG_DEBUG_BLK_CGROUP */
213 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
216 /* This is per cgroup per device grouping structure */
218 /* must be the first member */
219 struct blkg_policy_data pd
;
221 /* group service_tree member */
222 struct rb_node rb_node
;
224 /* group service_tree key */
227 unsigned int new_weight
;
228 unsigned int dev_weight
;
230 /* number of cfqq currently on this group */
234 * Per group busy queues average. Useful for workload slice calc. We
235 * create the array for each prio class but at run time it is used
236 * only for RT and BE class and slot for IDLE class remains unused.
237 * This is primarily done to avoid confusion and a gcc warning.
239 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
241 * rr lists of queues with requests. We maintain service trees for
242 * RT and BE classes. These trees are subdivided in subclasses
243 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
244 * class there is no subclassification and all the cfq queues go on
245 * a single tree service_tree_idle.
246 * Counts are embedded in the cfq_rb_root
248 struct cfq_rb_root service_trees
[2][3];
249 struct cfq_rb_root service_tree_idle
;
251 unsigned long saved_wl_slice
;
252 enum wl_type_t saved_wl_type
;
253 enum wl_class_t saved_wl_class
;
255 /* number of requests that are on the dispatch list or inside driver */
257 struct cfq_ttime ttime
;
258 struct cfqg_stats stats
;
262 struct io_cq icq
; /* must be the first member */
263 struct cfq_queue
*cfqq
[2];
264 struct cfq_ttime ttime
;
265 int ioprio
; /* the current ioprio */
266 #ifdef CONFIG_CFQ_GROUP_IOSCHED
267 uint64_t blkcg_id
; /* the current blkcg ID */
272 * Per block device queue structure
275 struct request_queue
*queue
;
276 /* Root service tree for cfq_groups */
277 struct cfq_rb_root grp_service_tree
;
278 struct cfq_group
*root_group
;
281 * The priority currently being served
283 enum wl_class_t serving_wl_class
;
284 enum wl_type_t serving_wl_type
;
285 unsigned long workload_expires
;
286 struct cfq_group
*serving_group
;
289 * Each priority tree is sorted by next_request position. These
290 * trees are used when determining if two or more queues are
291 * interleaving requests (see cfq_close_cooperator).
293 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
295 unsigned int busy_queues
;
296 unsigned int busy_sync_queues
;
302 * queue-depth detection
308 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
309 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
312 int hw_tag_est_depth
;
313 unsigned int hw_tag_samples
;
316 * idle window management
318 struct timer_list idle_slice_timer
;
319 struct work_struct unplug_work
;
321 struct cfq_queue
*active_queue
;
322 struct cfq_io_cq
*active_cic
;
325 * async queue for each priority case
327 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
328 struct cfq_queue
*async_idle_cfqq
;
330 sector_t last_position
;
333 * tunables, see top of file
335 unsigned int cfq_quantum
;
336 unsigned int cfq_fifo_expire
[2];
337 unsigned int cfq_back_penalty
;
338 unsigned int cfq_back_max
;
339 unsigned int cfq_slice
[2];
340 unsigned int cfq_slice_async_rq
;
341 unsigned int cfq_slice_idle
;
342 unsigned int cfq_group_idle
;
343 unsigned int cfq_latency
;
344 unsigned int cfq_target_latency
;
347 * Fallback dummy cfqq for extreme OOM conditions
349 struct cfq_queue oom_cfqq
;
351 unsigned long last_delayed_sync
;
354 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
356 static struct cfq_rb_root
*st_for(struct cfq_group
*cfqg
,
357 enum wl_class_t
class,
363 if (class == IDLE_WORKLOAD
)
364 return &cfqg
->service_tree_idle
;
366 return &cfqg
->service_trees
[class][type
];
369 enum cfqq_state_flags
{
370 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
371 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
372 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
373 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
374 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
375 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
376 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
377 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
378 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
379 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
380 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
381 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
382 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
385 #define CFQ_CFQQ_FNS(name) \
386 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
388 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
390 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
392 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
394 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
396 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
400 CFQ_CFQQ_FNS(wait_request
);
401 CFQ_CFQQ_FNS(must_dispatch
);
402 CFQ_CFQQ_FNS(must_alloc_slice
);
403 CFQ_CFQQ_FNS(fifo_expire
);
404 CFQ_CFQQ_FNS(idle_window
);
405 CFQ_CFQQ_FNS(prio_changed
);
406 CFQ_CFQQ_FNS(slice_new
);
409 CFQ_CFQQ_FNS(split_coop
);
411 CFQ_CFQQ_FNS(wait_busy
);
414 static inline struct cfq_group
*pd_to_cfqg(struct blkg_policy_data
*pd
)
416 return pd
? container_of(pd
, struct cfq_group
, pd
) : NULL
;
419 static inline struct blkcg_gq
*cfqg_to_blkg(struct cfq_group
*cfqg
)
421 return pd_to_blkg(&cfqg
->pd
);
424 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
426 /* cfqg stats flags */
427 enum cfqg_stats_flags
{
428 CFQG_stats_waiting
= 0,
433 #define CFQG_FLAG_FNS(name) \
434 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
436 stats->flags |= (1 << CFQG_stats_##name); \
438 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
440 stats->flags &= ~(1 << CFQG_stats_##name); \
442 static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
444 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
447 CFQG_FLAG_FNS(waiting)
448 CFQG_FLAG_FNS(idling
)
452 /* This should be called with the queue_lock held. */
453 static void cfqg_stats_update_group_wait_time(struct cfqg_stats
*stats
)
455 unsigned long long now
;
457 if (!cfqg_stats_waiting(stats
))
461 if (time_after64(now
, stats
->start_group_wait_time
))
462 blkg_stat_add(&stats
->group_wait_time
,
463 now
- stats
->start_group_wait_time
);
464 cfqg_stats_clear_waiting(stats
);
467 /* This should be called with the queue_lock held. */
468 static void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
,
469 struct cfq_group
*curr_cfqg
)
471 struct cfqg_stats
*stats
= &cfqg
->stats
;
473 if (cfqg_stats_waiting(stats
))
475 if (cfqg
== curr_cfqg
)
477 stats
->start_group_wait_time
= sched_clock();
478 cfqg_stats_mark_waiting(stats
);
481 /* This should be called with the queue_lock held. */
482 static void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
)
484 unsigned long long now
;
486 if (!cfqg_stats_empty(stats
))
490 if (time_after64(now
, stats
->start_empty_time
))
491 blkg_stat_add(&stats
->empty_time
,
492 now
- stats
->start_empty_time
);
493 cfqg_stats_clear_empty(stats
);
496 static void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
)
498 blkg_stat_add(&cfqg
->stats
.dequeue
, 1);
501 static void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
)
503 struct cfqg_stats
*stats
= &cfqg
->stats
;
505 if (blkg_rwstat_sum(&stats
->queued
))
509 * group is already marked empty. This can happen if cfqq got new
510 * request in parent group and moved to this group while being added
511 * to service tree. Just ignore the event and move on.
513 if (cfqg_stats_empty(stats
))
516 stats
->start_empty_time
= sched_clock();
517 cfqg_stats_mark_empty(stats
);
520 static void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
)
522 struct cfqg_stats
*stats
= &cfqg
->stats
;
524 if (cfqg_stats_idling(stats
)) {
525 unsigned long long now
= sched_clock();
527 if (time_after64(now
, stats
->start_idle_time
))
528 blkg_stat_add(&stats
->idle_time
,
529 now
- stats
->start_idle_time
);
530 cfqg_stats_clear_idling(stats
);
534 static void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
)
536 struct cfqg_stats
*stats
= &cfqg
->stats
;
538 BUG_ON(cfqg_stats_idling(stats
));
540 stats
->start_idle_time
= sched_clock();
541 cfqg_stats_mark_idling(stats
);
544 static void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
)
546 struct cfqg_stats
*stats
= &cfqg
->stats
;
548 blkg_stat_add(&stats
->avg_queue_size_sum
,
549 blkg_rwstat_sum(&stats
->queued
));
550 blkg_stat_add(&stats
->avg_queue_size_samples
, 1);
551 cfqg_stats_update_group_wait_time(stats
);
554 #else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
556 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group
*cfqg
, struct cfq_group
*curr_cfqg
) { }
557 static inline void cfqg_stats_end_empty_time(struct cfqg_stats
*stats
) { }
558 static inline void cfqg_stats_update_dequeue(struct cfq_group
*cfqg
) { }
559 static inline void cfqg_stats_set_start_empty_time(struct cfq_group
*cfqg
) { }
560 static inline void cfqg_stats_update_idle_time(struct cfq_group
*cfqg
) { }
561 static inline void cfqg_stats_set_start_idle_time(struct cfq_group
*cfqg
) { }
562 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group
*cfqg
) { }
564 #endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
566 #ifdef CONFIG_CFQ_GROUP_IOSCHED
568 static struct blkcg_policy blkcg_policy_cfq
;
570 static inline struct cfq_group
*blkg_to_cfqg(struct blkcg_gq
*blkg
)
572 return pd_to_cfqg(blkg_to_pd(blkg
, &blkcg_policy_cfq
));
575 static inline void cfqg_get(struct cfq_group
*cfqg
)
577 return blkg_get(cfqg_to_blkg(cfqg
));
580 static inline void cfqg_put(struct cfq_group
*cfqg
)
582 return blkg_put(cfqg_to_blkg(cfqg
));
585 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
588 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
589 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
590 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
594 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
597 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
598 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
601 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
602 struct cfq_group
*curr_cfqg
, int rw
)
604 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, 1);
605 cfqg_stats_end_empty_time(&cfqg
->stats
);
606 cfqg_stats_set_start_group_wait_time(cfqg
, curr_cfqg
);
609 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
610 unsigned long time
, unsigned long unaccounted_time
)
612 blkg_stat_add(&cfqg
->stats
.time
, time
);
613 #ifdef CONFIG_DEBUG_BLK_CGROUP
614 blkg_stat_add(&cfqg
->stats
.unaccounted_time
, unaccounted_time
);
618 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
)
620 blkg_rwstat_add(&cfqg
->stats
.queued
, rw
, -1);
623 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
)
625 blkg_rwstat_add(&cfqg
->stats
.merged
, rw
, 1);
628 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
629 uint64_t bytes
, int rw
)
631 blkg_stat_add(&cfqg
->stats
.sectors
, bytes
>> 9);
632 blkg_rwstat_add(&cfqg
->stats
.serviced
, rw
, 1);
633 blkg_rwstat_add(&cfqg
->stats
.service_bytes
, rw
, bytes
);
636 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
637 uint64_t start_time
, uint64_t io_start_time
, int rw
)
639 struct cfqg_stats
*stats
= &cfqg
->stats
;
640 unsigned long long now
= sched_clock();
642 if (time_after64(now
, io_start_time
))
643 blkg_rwstat_add(&stats
->service_time
, rw
, now
- io_start_time
);
644 if (time_after64(io_start_time
, start_time
))
645 blkg_rwstat_add(&stats
->wait_time
, rw
,
646 io_start_time
- start_time
);
649 static void cfq_pd_reset_stats(struct blkcg_gq
*blkg
)
651 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
652 struct cfqg_stats
*stats
= &cfqg
->stats
;
654 /* queued stats shouldn't be cleared */
655 blkg_rwstat_reset(&stats
->service_bytes
);
656 blkg_rwstat_reset(&stats
->serviced
);
657 blkg_rwstat_reset(&stats
->merged
);
658 blkg_rwstat_reset(&stats
->service_time
);
659 blkg_rwstat_reset(&stats
->wait_time
);
660 blkg_stat_reset(&stats
->time
);
661 #ifdef CONFIG_DEBUG_BLK_CGROUP
662 blkg_stat_reset(&stats
->unaccounted_time
);
663 blkg_stat_reset(&stats
->avg_queue_size_sum
);
664 blkg_stat_reset(&stats
->avg_queue_size_samples
);
665 blkg_stat_reset(&stats
->dequeue
);
666 blkg_stat_reset(&stats
->group_wait_time
);
667 blkg_stat_reset(&stats
->idle_time
);
668 blkg_stat_reset(&stats
->empty_time
);
672 #else /* CONFIG_CFQ_GROUP_IOSCHED */
674 static inline void cfqg_get(struct cfq_group
*cfqg
) { }
675 static inline void cfqg_put(struct cfq_group
*cfqg
) { }
677 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
678 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
679 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
681 static inline void cfqg_stats_update_io_add(struct cfq_group
*cfqg
,
682 struct cfq_group
*curr_cfqg
, int rw
) { }
683 static inline void cfqg_stats_update_timeslice_used(struct cfq_group
*cfqg
,
684 unsigned long time
, unsigned long unaccounted_time
) { }
685 static inline void cfqg_stats_update_io_remove(struct cfq_group
*cfqg
, int rw
) { }
686 static inline void cfqg_stats_update_io_merged(struct cfq_group
*cfqg
, int rw
) { }
687 static inline void cfqg_stats_update_dispatch(struct cfq_group
*cfqg
,
688 uint64_t bytes
, int rw
) { }
689 static inline void cfqg_stats_update_completion(struct cfq_group
*cfqg
,
690 uint64_t start_time
, uint64_t io_start_time
, int rw
) { }
692 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
694 #define cfq_log(cfqd, fmt, args...) \
695 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
697 /* Traverses through cfq group service trees */
698 #define for_each_cfqg_st(cfqg, i, j, st) \
699 for (i = 0; i <= IDLE_WORKLOAD; i++) \
700 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
701 : &cfqg->service_tree_idle; \
702 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
703 (i == IDLE_WORKLOAD && j == 0); \
704 j++, st = i < IDLE_WORKLOAD ? \
705 &cfqg->service_trees[i][j]: NULL) \
707 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
708 struct cfq_ttime
*ttime
, bool group_idle
)
711 if (!sample_valid(ttime
->ttime_samples
))
714 slice
= cfqd
->cfq_group_idle
;
716 slice
= cfqd
->cfq_slice_idle
;
717 return ttime
->ttime_mean
> slice
;
720 static inline bool iops_mode(struct cfq_data
*cfqd
)
723 * If we are not idling on queues and it is a NCQ drive, parallel
724 * execution of requests is on and measuring time is not possible
725 * in most of the cases until and unless we drive shallower queue
726 * depths and that becomes a performance bottleneck. In such cases
727 * switch to start providing fairness in terms of number of IOs.
729 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
735 static inline enum wl_class_t
cfqq_class(struct cfq_queue
*cfqq
)
737 if (cfq_class_idle(cfqq
))
738 return IDLE_WORKLOAD
;
739 if (cfq_class_rt(cfqq
))
745 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
747 if (!cfq_cfqq_sync(cfqq
))
748 return ASYNC_WORKLOAD
;
749 if (!cfq_cfqq_idle_window(cfqq
))
750 return SYNC_NOIDLE_WORKLOAD
;
751 return SYNC_WORKLOAD
;
754 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class
,
755 struct cfq_data
*cfqd
,
756 struct cfq_group
*cfqg
)
758 if (wl_class
== IDLE_WORKLOAD
)
759 return cfqg
->service_tree_idle
.count
;
761 return cfqg
->service_trees
[wl_class
][ASYNC_WORKLOAD
].count
+
762 cfqg
->service_trees
[wl_class
][SYNC_NOIDLE_WORKLOAD
].count
+
763 cfqg
->service_trees
[wl_class
][SYNC_WORKLOAD
].count
;
766 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
767 struct cfq_group
*cfqg
)
769 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
+
770 cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
773 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
774 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
,
775 struct cfq_io_cq
*cic
, struct bio
*bio
,
778 static inline struct cfq_io_cq
*icq_to_cic(struct io_cq
*icq
)
780 /* cic->icq is the first member, %NULL will convert to %NULL */
781 return container_of(icq
, struct cfq_io_cq
, icq
);
784 static inline struct cfq_io_cq
*cfq_cic_lookup(struct cfq_data
*cfqd
,
785 struct io_context
*ioc
)
788 return icq_to_cic(ioc_lookup_icq(ioc
, cfqd
->queue
));
792 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_cq
*cic
, bool is_sync
)
794 return cic
->cfqq
[is_sync
];
797 static inline void cic_set_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
,
800 cic
->cfqq
[is_sync
] = cfqq
;
803 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_cq
*cic
)
805 return cic
->icq
.q
->elevator
->elevator_data
;
809 * We regard a request as SYNC, if it's either a read or has the SYNC bit
810 * set (in which case it could also be direct WRITE).
812 static inline bool cfq_bio_sync(struct bio
*bio
)
814 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
818 * scheduler run of queue, if there are requests pending and no one in the
819 * driver that will restart queueing
821 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
823 if (cfqd
->busy_queues
) {
824 cfq_log(cfqd
, "schedule dispatch");
825 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
830 * Scale schedule slice based on io priority. Use the sync time slice only
831 * if a queue is marked sync and has sync io queued. A sync queue with async
832 * io only, should not get full sync slice length.
834 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
837 const int base_slice
= cfqd
->cfq_slice
[sync
];
839 WARN_ON(prio
>= IOPRIO_BE_NR
);
841 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
845 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
847 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
850 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
852 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
854 d
= d
* CFQ_WEIGHT_DEFAULT
;
855 do_div(d
, cfqg
->weight
);
859 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
861 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
863 min_vdisktime
= vdisktime
;
865 return min_vdisktime
;
868 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
870 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
872 min_vdisktime
= vdisktime
;
874 return min_vdisktime
;
877 static void update_min_vdisktime(struct cfq_rb_root
*st
)
879 struct cfq_group
*cfqg
;
882 cfqg
= rb_entry_cfqg(st
->left
);
883 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
889 * get averaged number of queues of RT/BE priority.
890 * average is updated, with a formula that gives more weight to higher numbers,
891 * to quickly follows sudden increases and decrease slowly
894 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
895 struct cfq_group
*cfqg
, bool rt
)
897 unsigned min_q
, max_q
;
898 unsigned mult
= cfq_hist_divisor
- 1;
899 unsigned round
= cfq_hist_divisor
/ 2;
900 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
902 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
903 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
904 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
906 return cfqg
->busy_queues_avg
[rt
];
909 static inline unsigned
910 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
912 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
914 return cfqd
->cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
917 static inline unsigned
918 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
920 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
921 if (cfqd
->cfq_latency
) {
923 * interested queues (we consider only the ones with the same
924 * priority class in the cfq group)
926 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
928 unsigned sync_slice
= cfqd
->cfq_slice
[1];
929 unsigned expect_latency
= sync_slice
* iq
;
930 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
932 if (expect_latency
> group_slice
) {
933 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
934 /* scale low_slice according to IO priority
935 * and sync vs async */
937 min(slice
, base_low_slice
* slice
/ sync_slice
);
938 /* the adapted slice value is scaled to fit all iqs
939 * into the target latency */
940 slice
= max(slice
* group_slice
/ expect_latency
,
948 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
950 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
952 cfqq
->slice_start
= jiffies
;
953 cfqq
->slice_end
= jiffies
+ slice
;
954 cfqq
->allocated_slice
= slice
;
955 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
959 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
960 * isn't valid until the first request from the dispatch is activated
961 * and the slice time set.
963 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
965 if (cfq_cfqq_slice_new(cfqq
))
967 if (time_before(jiffies
, cfqq
->slice_end
))
974 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
975 * We choose the request that is closest to the head right now. Distance
976 * behind the head is penalized and only allowed to a certain extent.
978 static struct request
*
979 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
981 sector_t s1
, s2
, d1
= 0, d2
= 0;
982 unsigned long back_max
;
983 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
984 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
985 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
987 if (rq1
== NULL
|| rq1
== rq2
)
992 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
993 return rq_is_sync(rq1
) ? rq1
: rq2
;
995 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
996 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
998 s1
= blk_rq_pos(rq1
);
999 s2
= blk_rq_pos(rq2
);
1002 * by definition, 1KiB is 2 sectors
1004 back_max
= cfqd
->cfq_back_max
* 2;
1007 * Strict one way elevator _except_ in the case where we allow
1008 * short backward seeks which are biased as twice the cost of a
1009 * similar forward seek.
1013 else if (s1
+ back_max
>= last
)
1014 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
1016 wrap
|= CFQ_RQ1_WRAP
;
1020 else if (s2
+ back_max
>= last
)
1021 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
1023 wrap
|= CFQ_RQ2_WRAP
;
1025 /* Found required data */
1028 * By doing switch() on the bit mask "wrap" we avoid having to
1029 * check two variables for all permutations: --> faster!
1032 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1048 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
1051 * Since both rqs are wrapped,
1052 * start with the one that's further behind head
1053 * (--> only *one* back seek required),
1054 * since back seek takes more time than forward.
1064 * The below is leftmost cache rbtree addon
1066 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
1068 /* Service tree is empty */
1073 root
->left
= rb_first(&root
->rb
);
1076 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
1081 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
1084 root
->left
= rb_first(&root
->rb
);
1087 return rb_entry_cfqg(root
->left
);
1092 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
1098 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
1100 if (root
->left
== n
)
1102 rb_erase_init(n
, &root
->rb
);
1107 * would be nice to take fifo expire time into account as well
1109 static struct request
*
1110 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1111 struct request
*last
)
1113 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
1114 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
1115 struct request
*next
= NULL
, *prev
= NULL
;
1117 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
1120 prev
= rb_entry_rq(rbprev
);
1123 next
= rb_entry_rq(rbnext
);
1125 rbnext
= rb_first(&cfqq
->sort_list
);
1126 if (rbnext
&& rbnext
!= &last
->rb_node
)
1127 next
= rb_entry_rq(rbnext
);
1130 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
1133 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
1134 struct cfq_queue
*cfqq
)
1137 * just an approximation, should be ok.
1139 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
1140 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
1144 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1146 return cfqg
->vdisktime
- st
->min_vdisktime
;
1150 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1152 struct rb_node
**node
= &st
->rb
.rb_node
;
1153 struct rb_node
*parent
= NULL
;
1154 struct cfq_group
*__cfqg
;
1155 s64 key
= cfqg_key(st
, cfqg
);
1158 while (*node
!= NULL
) {
1160 __cfqg
= rb_entry_cfqg(parent
);
1162 if (key
< cfqg_key(st
, __cfqg
))
1163 node
= &parent
->rb_left
;
1165 node
= &parent
->rb_right
;
1171 st
->left
= &cfqg
->rb_node
;
1173 rb_link_node(&cfqg
->rb_node
, parent
, node
);
1174 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
1178 cfq_update_group_weight(struct cfq_group
*cfqg
)
1180 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1181 if (cfqg
->new_weight
) {
1182 cfqg
->weight
= cfqg
->new_weight
;
1183 cfqg
->new_weight
= 0;
1188 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1190 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
1192 cfq_update_group_weight(cfqg
);
1193 __cfq_group_service_tree_add(st
, cfqg
);
1194 st
->total_weight
+= cfqg
->weight
;
1198 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1200 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1201 struct cfq_group
*__cfqg
;
1205 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1209 * Currently put the group at the end. Later implement something
1210 * so that groups get lesser vtime based on their weights, so that
1211 * if group does not loose all if it was not continuously backlogged.
1213 n
= rb_last(&st
->rb
);
1215 __cfqg
= rb_entry_cfqg(n
);
1216 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
1218 cfqg
->vdisktime
= st
->min_vdisktime
;
1219 cfq_group_service_tree_add(st
, cfqg
);
1223 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
1225 st
->total_weight
-= cfqg
->weight
;
1226 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
1227 cfq_rb_erase(&cfqg
->rb_node
, st
);
1231 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1233 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1235 BUG_ON(cfqg
->nr_cfqq
< 1);
1238 /* If there are other cfq queues under this group, don't delete it */
1242 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
1243 cfq_group_service_tree_del(st
, cfqg
);
1244 cfqg
->saved_wl_slice
= 0;
1245 cfqg_stats_update_dequeue(cfqg
);
1248 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
1249 unsigned int *unaccounted_time
)
1251 unsigned int slice_used
;
1254 * Queue got expired before even a single request completed or
1255 * got expired immediately after first request completion.
1257 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
1259 * Also charge the seek time incurred to the group, otherwise
1260 * if there are mutiple queues in the group, each can dispatch
1261 * a single request on seeky media and cause lots of seek time
1262 * and group will never know it.
1264 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
1267 slice_used
= jiffies
- cfqq
->slice_start
;
1268 if (slice_used
> cfqq
->allocated_slice
) {
1269 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
1270 slice_used
= cfqq
->allocated_slice
;
1272 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
1273 *unaccounted_time
+= cfqq
->slice_start
-
1274 cfqq
->dispatch_start
;
1280 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
1281 struct cfq_queue
*cfqq
)
1283 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1284 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
1285 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
1286 - cfqg
->service_tree_idle
.count
;
1288 BUG_ON(nr_sync
< 0);
1289 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
1291 if (iops_mode(cfqd
))
1292 charge
= cfqq
->slice_dispatch
;
1293 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
1294 charge
= cfqq
->allocated_slice
;
1296 /* Can't update vdisktime while group is on service tree */
1297 cfq_group_service_tree_del(st
, cfqg
);
1298 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
1299 /* If a new weight was requested, update now, off tree */
1300 cfq_group_service_tree_add(st
, cfqg
);
1302 /* This group is being expired. Save the context */
1303 if (time_after(cfqd
->workload_expires
, jiffies
)) {
1304 cfqg
->saved_wl_slice
= cfqd
->workload_expires
1306 cfqg
->saved_wl_type
= cfqd
->serving_wl_type
;
1307 cfqg
->saved_wl_class
= cfqd
->serving_wl_class
;
1309 cfqg
->saved_wl_slice
= 0;
1311 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1313 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1314 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1315 used_sl
, cfqq
->slice_dispatch
, charge
,
1316 iops_mode(cfqd
), cfqq
->nr_sectors
);
1317 cfqg_stats_update_timeslice_used(cfqg
, used_sl
, unaccounted_sl
);
1318 cfqg_stats_set_start_empty_time(cfqg
);
1322 * cfq_init_cfqg_base - initialize base part of a cfq_group
1323 * @cfqg: cfq_group to initialize
1325 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1326 * is enabled or not.
1328 static void cfq_init_cfqg_base(struct cfq_group
*cfqg
)
1330 struct cfq_rb_root
*st
;
1333 for_each_cfqg_st(cfqg
, i
, j
, st
)
1335 RB_CLEAR_NODE(&cfqg
->rb_node
);
1337 cfqg
->ttime
.last_end_request
= jiffies
;
1340 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1341 static void cfq_pd_init(struct blkcg_gq
*blkg
)
1343 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1345 cfq_init_cfqg_base(cfqg
);
1346 cfqg
->weight
= blkg
->blkcg
->cfq_weight
;
1350 * Search for the cfq group current task belongs to. request_queue lock must
1353 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1354 struct blkcg
*blkcg
)
1356 struct request_queue
*q
= cfqd
->queue
;
1357 struct cfq_group
*cfqg
= NULL
;
1359 /* avoid lookup for the common case where there's no blkcg */
1360 if (blkcg
== &blkcg_root
) {
1361 cfqg
= cfqd
->root_group
;
1363 struct blkcg_gq
*blkg
;
1365 blkg
= blkg_lookup_create(blkcg
, q
);
1367 cfqg
= blkg_to_cfqg(blkg
);
1373 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1375 /* Currently, all async queues are mapped to root group */
1376 if (!cfq_cfqq_sync(cfqq
))
1377 cfqg
= cfqq
->cfqd
->root_group
;
1380 /* cfqq reference on cfqg */
1384 static u64
cfqg_prfill_weight_device(struct seq_file
*sf
,
1385 struct blkg_policy_data
*pd
, int off
)
1387 struct cfq_group
*cfqg
= pd_to_cfqg(pd
);
1389 if (!cfqg
->dev_weight
)
1391 return __blkg_prfill_u64(sf
, pd
, cfqg
->dev_weight
);
1394 static int cfqg_print_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1395 struct seq_file
*sf
)
1397 blkcg_print_blkgs(sf
, cgroup_to_blkcg(cgrp
),
1398 cfqg_prfill_weight_device
, &blkcg_policy_cfq
, 0,
1403 static int cfq_print_weight(struct cgroup
*cgrp
, struct cftype
*cft
,
1404 struct seq_file
*sf
)
1406 seq_printf(sf
, "%u\n", cgroup_to_blkcg(cgrp
)->cfq_weight
);
1410 static int cfqg_set_weight_device(struct cgroup
*cgrp
, struct cftype
*cft
,
1413 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
1414 struct blkg_conf_ctx ctx
;
1415 struct cfq_group
*cfqg
;
1418 ret
= blkg_conf_prep(blkcg
, &blkcg_policy_cfq
, buf
, &ctx
);
1423 cfqg
= blkg_to_cfqg(ctx
.blkg
);
1424 if (!ctx
.v
|| (ctx
.v
>= CFQ_WEIGHT_MIN
&& ctx
.v
<= CFQ_WEIGHT_MAX
)) {
1425 cfqg
->dev_weight
= ctx
.v
;
1426 cfqg
->new_weight
= cfqg
->dev_weight
?: blkcg
->cfq_weight
;
1430 blkg_conf_finish(&ctx
);
1434 static int cfq_set_weight(struct cgroup
*cgrp
, struct cftype
*cft
, u64 val
)
1436 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
1437 struct blkcg_gq
*blkg
;
1438 struct hlist_node
*n
;
1440 if (val
< CFQ_WEIGHT_MIN
|| val
> CFQ_WEIGHT_MAX
)
1443 spin_lock_irq(&blkcg
->lock
);
1444 blkcg
->cfq_weight
= (unsigned int)val
;
1446 hlist_for_each_entry(blkg
, n
, &blkcg
->blkg_list
, blkcg_node
) {
1447 struct cfq_group
*cfqg
= blkg_to_cfqg(blkg
);
1449 if (cfqg
&& !cfqg
->dev_weight
)
1450 cfqg
->new_weight
= blkcg
->cfq_weight
;
1453 spin_unlock_irq(&blkcg
->lock
);
1457 static int cfqg_print_stat(struct cgroup
*cgrp
, struct cftype
*cft
,
1458 struct seq_file
*sf
)
1460 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
1462 blkcg_print_blkgs(sf
, blkcg
, blkg_prfill_stat
, &blkcg_policy_cfq
,
1463 cft
->private, false);
1467 static int cfqg_print_rwstat(struct cgroup
*cgrp
, struct cftype
*cft
,
1468 struct seq_file
*sf
)
1470 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
1472 blkcg_print_blkgs(sf
, blkcg
, blkg_prfill_rwstat
, &blkcg_policy_cfq
,
1473 cft
->private, true);
1477 #ifdef CONFIG_DEBUG_BLK_CGROUP
1478 static u64
cfqg_prfill_avg_queue_size(struct seq_file
*sf
,
1479 struct blkg_policy_data
*pd
, int off
)
1481 struct cfq_group
*cfqg
= pd_to_cfqg(pd
);
1482 u64 samples
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_samples
);
1486 v
= blkg_stat_read(&cfqg
->stats
.avg_queue_size_sum
);
1489 __blkg_prfill_u64(sf
, pd
, v
);
1493 /* print avg_queue_size */
1494 static int cfqg_print_avg_queue_size(struct cgroup
*cgrp
, struct cftype
*cft
,
1495 struct seq_file
*sf
)
1497 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
1499 blkcg_print_blkgs(sf
, blkcg
, cfqg_prfill_avg_queue_size
,
1500 &blkcg_policy_cfq
, 0, false);
1503 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1505 static struct cftype cfq_blkcg_files
[] = {
1507 .name
= "weight_device",
1508 .read_seq_string
= cfqg_print_weight_device
,
1509 .write_string
= cfqg_set_weight_device
,
1510 .max_write_len
= 256,
1514 .read_seq_string
= cfq_print_weight
,
1515 .write_u64
= cfq_set_weight
,
1519 .private = offsetof(struct cfq_group
, stats
.time
),
1520 .read_seq_string
= cfqg_print_stat
,
1524 .private = offsetof(struct cfq_group
, stats
.sectors
),
1525 .read_seq_string
= cfqg_print_stat
,
1528 .name
= "io_service_bytes",
1529 .private = offsetof(struct cfq_group
, stats
.service_bytes
),
1530 .read_seq_string
= cfqg_print_rwstat
,
1533 .name
= "io_serviced",
1534 .private = offsetof(struct cfq_group
, stats
.serviced
),
1535 .read_seq_string
= cfqg_print_rwstat
,
1538 .name
= "io_service_time",
1539 .private = offsetof(struct cfq_group
, stats
.service_time
),
1540 .read_seq_string
= cfqg_print_rwstat
,
1543 .name
= "io_wait_time",
1544 .private = offsetof(struct cfq_group
, stats
.wait_time
),
1545 .read_seq_string
= cfqg_print_rwstat
,
1548 .name
= "io_merged",
1549 .private = offsetof(struct cfq_group
, stats
.merged
),
1550 .read_seq_string
= cfqg_print_rwstat
,
1553 .name
= "io_queued",
1554 .private = offsetof(struct cfq_group
, stats
.queued
),
1555 .read_seq_string
= cfqg_print_rwstat
,
1557 #ifdef CONFIG_DEBUG_BLK_CGROUP
1559 .name
= "avg_queue_size",
1560 .read_seq_string
= cfqg_print_avg_queue_size
,
1563 .name
= "group_wait_time",
1564 .private = offsetof(struct cfq_group
, stats
.group_wait_time
),
1565 .read_seq_string
= cfqg_print_stat
,
1568 .name
= "idle_time",
1569 .private = offsetof(struct cfq_group
, stats
.idle_time
),
1570 .read_seq_string
= cfqg_print_stat
,
1573 .name
= "empty_time",
1574 .private = offsetof(struct cfq_group
, stats
.empty_time
),
1575 .read_seq_string
= cfqg_print_stat
,
1579 .private = offsetof(struct cfq_group
, stats
.dequeue
),
1580 .read_seq_string
= cfqg_print_stat
,
1583 .name
= "unaccounted_time",
1584 .private = offsetof(struct cfq_group
, stats
.unaccounted_time
),
1585 .read_seq_string
= cfqg_print_stat
,
1587 #endif /* CONFIG_DEBUG_BLK_CGROUP */
1590 #else /* GROUP_IOSCHED */
1591 static struct cfq_group
*cfq_lookup_create_cfqg(struct cfq_data
*cfqd
,
1592 struct blkcg
*blkcg
)
1594 return cfqd
->root_group
;
1598 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1602 #endif /* GROUP_IOSCHED */
1605 * The cfqd->service_trees holds all pending cfq_queue's that have
1606 * requests waiting to be processed. It is sorted in the order that
1607 * we will service the queues.
1609 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1612 struct rb_node
**p
, *parent
;
1613 struct cfq_queue
*__cfqq
;
1614 unsigned long rb_key
;
1615 struct cfq_rb_root
*st
;
1619 st
= st_for(cfqq
->cfqg
, cfqq_class(cfqq
), cfqq_type(cfqq
));
1620 if (cfq_class_idle(cfqq
)) {
1621 rb_key
= CFQ_IDLE_DELAY
;
1622 parent
= rb_last(&st
->rb
);
1623 if (parent
&& parent
!= &cfqq
->rb_node
) {
1624 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1625 rb_key
+= __cfqq
->rb_key
;
1628 } else if (!add_front
) {
1630 * Get our rb key offset. Subtract any residual slice
1631 * value carried from last service. A negative resid
1632 * count indicates slice overrun, and this should position
1633 * the next service time further away in the tree.
1635 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1636 rb_key
-= cfqq
->slice_resid
;
1637 cfqq
->slice_resid
= 0;
1640 __cfqq
= cfq_rb_first(st
);
1641 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1644 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1647 * same position, nothing more to do
1649 if (rb_key
== cfqq
->rb_key
&& cfqq
->service_tree
== st
)
1652 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1653 cfqq
->service_tree
= NULL
;
1658 cfqq
->service_tree
= st
;
1659 p
= &st
->rb
.rb_node
;
1664 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1667 * sort by key, that represents service time.
1669 if (time_before(rb_key
, __cfqq
->rb_key
))
1672 n
= &(*p
)->rb_right
;
1680 st
->left
= &cfqq
->rb_node
;
1682 cfqq
->rb_key
= rb_key
;
1683 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1684 rb_insert_color(&cfqq
->rb_node
, &st
->rb
);
1686 if (add_front
|| !new_cfqq
)
1688 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1691 static struct cfq_queue
*
1692 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1693 sector_t sector
, struct rb_node
**ret_parent
,
1694 struct rb_node
***rb_link
)
1696 struct rb_node
**p
, *parent
;
1697 struct cfq_queue
*cfqq
= NULL
;
1705 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1708 * Sort strictly based on sector. Smallest to the left,
1709 * largest to the right.
1711 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1712 n
= &(*p
)->rb_right
;
1713 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1721 *ret_parent
= parent
;
1727 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1729 struct rb_node
**p
, *parent
;
1730 struct cfq_queue
*__cfqq
;
1733 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1734 cfqq
->p_root
= NULL
;
1737 if (cfq_class_idle(cfqq
))
1742 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1743 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1744 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1746 rb_link_node(&cfqq
->p_node
, parent
, p
);
1747 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1749 cfqq
->p_root
= NULL
;
1753 * Update cfqq's position in the service tree.
1755 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1758 * Resorting requires the cfqq to be on the RR list already.
1760 if (cfq_cfqq_on_rr(cfqq
)) {
1761 cfq_service_tree_add(cfqd
, cfqq
, 0);
1762 cfq_prio_tree_add(cfqd
, cfqq
);
1767 * add to busy list of queues for service, trying to be fair in ordering
1768 * the pending list according to last request service
1770 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1772 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1773 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1774 cfq_mark_cfqq_on_rr(cfqq
);
1775 cfqd
->busy_queues
++;
1776 if (cfq_cfqq_sync(cfqq
))
1777 cfqd
->busy_sync_queues
++;
1779 cfq_resort_rr_list(cfqd
, cfqq
);
1783 * Called when the cfqq no longer has requests pending, remove it from
1786 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1788 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1789 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1790 cfq_clear_cfqq_on_rr(cfqq
);
1792 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1793 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1794 cfqq
->service_tree
= NULL
;
1797 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1798 cfqq
->p_root
= NULL
;
1801 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1802 BUG_ON(!cfqd
->busy_queues
);
1803 cfqd
->busy_queues
--;
1804 if (cfq_cfqq_sync(cfqq
))
1805 cfqd
->busy_sync_queues
--;
1809 * rb tree support functions
1811 static void cfq_del_rq_rb(struct request
*rq
)
1813 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1814 const int sync
= rq_is_sync(rq
);
1816 BUG_ON(!cfqq
->queued
[sync
]);
1817 cfqq
->queued
[sync
]--;
1819 elv_rb_del(&cfqq
->sort_list
, rq
);
1821 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1823 * Queue will be deleted from service tree when we actually
1824 * expire it later. Right now just remove it from prio tree
1828 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1829 cfqq
->p_root
= NULL
;
1834 static void cfq_add_rq_rb(struct request
*rq
)
1836 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1837 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1838 struct request
*prev
;
1840 cfqq
->queued
[rq_is_sync(rq
)]++;
1842 elv_rb_add(&cfqq
->sort_list
, rq
);
1844 if (!cfq_cfqq_on_rr(cfqq
))
1845 cfq_add_cfqq_rr(cfqd
, cfqq
);
1848 * check if this request is a better next-serve candidate
1850 prev
= cfqq
->next_rq
;
1851 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1854 * adjust priority tree position, if ->next_rq changes
1856 if (prev
!= cfqq
->next_rq
)
1857 cfq_prio_tree_add(cfqd
, cfqq
);
1859 BUG_ON(!cfqq
->next_rq
);
1862 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1864 elv_rb_del(&cfqq
->sort_list
, rq
);
1865 cfqq
->queued
[rq_is_sync(rq
)]--;
1866 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1868 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqq
->cfqd
->serving_group
,
1872 static struct request
*
1873 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1875 struct task_struct
*tsk
= current
;
1876 struct cfq_io_cq
*cic
;
1877 struct cfq_queue
*cfqq
;
1879 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1883 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1885 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1887 return elv_rb_find(&cfqq
->sort_list
, sector
);
1893 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1895 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1897 cfqd
->rq_in_driver
++;
1898 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1899 cfqd
->rq_in_driver
);
1901 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1904 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1906 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1908 WARN_ON(!cfqd
->rq_in_driver
);
1909 cfqd
->rq_in_driver
--;
1910 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1911 cfqd
->rq_in_driver
);
1914 static void cfq_remove_request(struct request
*rq
)
1916 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1918 if (cfqq
->next_rq
== rq
)
1919 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1921 list_del_init(&rq
->queuelist
);
1924 cfqq
->cfqd
->rq_queued
--;
1925 cfqg_stats_update_io_remove(RQ_CFQG(rq
), rq
->cmd_flags
);
1926 if (rq
->cmd_flags
& REQ_PRIO
) {
1927 WARN_ON(!cfqq
->prio_pending
);
1928 cfqq
->prio_pending
--;
1932 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1935 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1936 struct request
*__rq
;
1938 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1939 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1941 return ELEVATOR_FRONT_MERGE
;
1944 return ELEVATOR_NO_MERGE
;
1947 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1950 if (type
== ELEVATOR_FRONT_MERGE
) {
1951 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1953 cfq_reposition_rq_rb(cfqq
, req
);
1957 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1960 cfqg_stats_update_io_merged(RQ_CFQG(req
), bio
->bi_rw
);
1964 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1965 struct request
*next
)
1967 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1968 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1971 * reposition in fifo if next is older than rq
1973 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1974 time_before(rq_fifo_time(next
), rq_fifo_time(rq
)) &&
1975 cfqq
== RQ_CFQQ(next
)) {
1976 list_move(&rq
->queuelist
, &next
->queuelist
);
1977 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1980 if (cfqq
->next_rq
== next
)
1982 cfq_remove_request(next
);
1983 cfqg_stats_update_io_merged(RQ_CFQG(rq
), next
->cmd_flags
);
1985 cfqq
= RQ_CFQQ(next
);
1987 * all requests of this queue are merged to other queues, delete it
1988 * from the service tree. If it's the active_queue,
1989 * cfq_dispatch_requests() will choose to expire it or do idle
1991 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
) &&
1992 cfqq
!= cfqd
->active_queue
)
1993 cfq_del_cfqq_rr(cfqd
, cfqq
);
1996 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1999 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2000 struct cfq_io_cq
*cic
;
2001 struct cfq_queue
*cfqq
;
2004 * Disallow merge of a sync bio into an async request.
2006 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
2010 * Lookup the cfqq that this bio will be queued with and allow
2011 * merge only if rq is queued there.
2013 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
2017 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
2018 return cfqq
== RQ_CFQQ(rq
);
2021 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2023 del_timer(&cfqd
->idle_slice_timer
);
2024 cfqg_stats_update_idle_time(cfqq
->cfqg
);
2027 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
2028 struct cfq_queue
*cfqq
)
2031 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_class:%d wl_type:%d",
2032 cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2033 cfqg_stats_update_avg_queue_size(cfqq
->cfqg
);
2034 cfqq
->slice_start
= 0;
2035 cfqq
->dispatch_start
= jiffies
;
2036 cfqq
->allocated_slice
= 0;
2037 cfqq
->slice_end
= 0;
2038 cfqq
->slice_dispatch
= 0;
2039 cfqq
->nr_sectors
= 0;
2041 cfq_clear_cfqq_wait_request(cfqq
);
2042 cfq_clear_cfqq_must_dispatch(cfqq
);
2043 cfq_clear_cfqq_must_alloc_slice(cfqq
);
2044 cfq_clear_cfqq_fifo_expire(cfqq
);
2045 cfq_mark_cfqq_slice_new(cfqq
);
2047 cfq_del_timer(cfqd
, cfqq
);
2050 cfqd
->active_queue
= cfqq
;
2054 * current cfqq expired its slice (or was too idle), select new one
2057 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2060 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
2062 if (cfq_cfqq_wait_request(cfqq
))
2063 cfq_del_timer(cfqd
, cfqq
);
2065 cfq_clear_cfqq_wait_request(cfqq
);
2066 cfq_clear_cfqq_wait_busy(cfqq
);
2069 * If this cfqq is shared between multiple processes, check to
2070 * make sure that those processes are still issuing I/Os within
2071 * the mean seek distance. If not, it may be time to break the
2072 * queues apart again.
2074 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
2075 cfq_mark_cfqq_split_coop(cfqq
);
2078 * store what was left of this slice, if the queue idled/timed out
2081 if (cfq_cfqq_slice_new(cfqq
))
2082 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
2084 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
2085 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
2088 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
2090 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
2091 cfq_del_cfqq_rr(cfqd
, cfqq
);
2093 cfq_resort_rr_list(cfqd
, cfqq
);
2095 if (cfqq
== cfqd
->active_queue
)
2096 cfqd
->active_queue
= NULL
;
2098 if (cfqd
->active_cic
) {
2099 put_io_context(cfqd
->active_cic
->icq
.ioc
);
2100 cfqd
->active_cic
= NULL
;
2104 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
2106 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2109 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
2113 * Get next queue for service. Unless we have a queue preemption,
2114 * we'll simply select the first cfqq in the service tree.
2116 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
2118 struct cfq_rb_root
*st
= st_for(cfqd
->serving_group
,
2119 cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2121 if (!cfqd
->rq_queued
)
2124 /* There is nothing to dispatch */
2127 if (RB_EMPTY_ROOT(&st
->rb
))
2129 return cfq_rb_first(st
);
2132 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
2134 struct cfq_group
*cfqg
;
2135 struct cfq_queue
*cfqq
;
2137 struct cfq_rb_root
*st
;
2139 if (!cfqd
->rq_queued
)
2142 cfqg
= cfq_get_next_cfqg(cfqd
);
2146 for_each_cfqg_st(cfqg
, i
, j
, st
)
2147 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
2153 * Get and set a new active queue for service.
2155 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
2156 struct cfq_queue
*cfqq
)
2159 cfqq
= cfq_get_next_queue(cfqd
);
2161 __cfq_set_active_queue(cfqd
, cfqq
);
2165 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
2168 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
2169 return blk_rq_pos(rq
) - cfqd
->last_position
;
2171 return cfqd
->last_position
- blk_rq_pos(rq
);
2174 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2177 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
2180 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
2181 struct cfq_queue
*cur_cfqq
)
2183 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
2184 struct rb_node
*parent
, *node
;
2185 struct cfq_queue
*__cfqq
;
2186 sector_t sector
= cfqd
->last_position
;
2188 if (RB_EMPTY_ROOT(root
))
2192 * First, if we find a request starting at the end of the last
2193 * request, choose it.
2195 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
2200 * If the exact sector wasn't found, the parent of the NULL leaf
2201 * will contain the closest sector.
2203 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
2204 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2207 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
2208 node
= rb_next(&__cfqq
->p_node
);
2210 node
= rb_prev(&__cfqq
->p_node
);
2214 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
2215 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
2223 * cur_cfqq - passed in so that we don't decide that the current queue is
2224 * closely cooperating with itself.
2226 * So, basically we're assuming that that cur_cfqq has dispatched at least
2227 * one request, and that cfqd->last_position reflects a position on the disk
2228 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
2231 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
2232 struct cfq_queue
*cur_cfqq
)
2234 struct cfq_queue
*cfqq
;
2236 if (cfq_class_idle(cur_cfqq
))
2238 if (!cfq_cfqq_sync(cur_cfqq
))
2240 if (CFQQ_SEEKY(cur_cfqq
))
2244 * Don't search priority tree if it's the only queue in the group.
2246 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
2250 * We should notice if some of the queues are cooperating, eg
2251 * working closely on the same area of the disk. In that case,
2252 * we can group them together and don't waste time idling.
2254 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
2258 /* If new queue belongs to different cfq_group, don't choose it */
2259 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
2263 * It only makes sense to merge sync queues.
2265 if (!cfq_cfqq_sync(cfqq
))
2267 if (CFQQ_SEEKY(cfqq
))
2271 * Do not merge queues of different priority classes
2273 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
2280 * Determine whether we should enforce idle window for this queue.
2283 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2285 enum wl_class_t wl_class
= cfqq_class(cfqq
);
2286 struct cfq_rb_root
*st
= cfqq
->service_tree
;
2291 if (!cfqd
->cfq_slice_idle
)
2294 /* We never do for idle class queues. */
2295 if (wl_class
== IDLE_WORKLOAD
)
2298 /* We do for queues that were marked with idle window flag. */
2299 if (cfq_cfqq_idle_window(cfqq
) &&
2300 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
2304 * Otherwise, we do only if they are the last ones
2305 * in their service tree.
2307 if (st
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
2308 !cfq_io_thinktime_big(cfqd
, &st
->ttime
, false))
2310 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d", st
->count
);
2314 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2316 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2317 struct cfq_io_cq
*cic
;
2318 unsigned long sl
, group_idle
= 0;
2321 * SSD device without seek penalty, disable idling. But only do so
2322 * for devices that support queuing, otherwise we still have a problem
2323 * with sync vs async workloads.
2325 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2328 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2329 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2332 * idle is disabled, either manually or by past process history
2334 if (!cfq_should_idle(cfqd
, cfqq
)) {
2335 /* no queue idling. Check for group idling */
2336 if (cfqd
->cfq_group_idle
)
2337 group_idle
= cfqd
->cfq_group_idle
;
2343 * still active requests from this queue, don't idle
2345 if (cfqq
->dispatched
)
2349 * task has exited, don't wait
2351 cic
= cfqd
->active_cic
;
2352 if (!cic
|| !atomic_read(&cic
->icq
.ioc
->active_ref
))
2356 * If our average think time is larger than the remaining time
2357 * slice, then don't idle. This avoids overrunning the allotted
2360 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2361 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2362 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2363 cic
->ttime
.ttime_mean
);
2367 /* There are other queues in the group, don't do group idle */
2368 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2371 cfq_mark_cfqq_wait_request(cfqq
);
2374 sl
= cfqd
->cfq_group_idle
;
2376 sl
= cfqd
->cfq_slice_idle
;
2378 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2379 cfqg_stats_set_start_idle_time(cfqq
->cfqg
);
2380 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2381 group_idle
? 1 : 0);
2385 * Move request from internal lists to the request queue dispatch list.
2387 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2389 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2390 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2392 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2394 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2395 cfq_remove_request(rq
);
2397 (RQ_CFQG(rq
))->dispatched
++;
2398 elv_dispatch_sort(q
, rq
);
2400 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2401 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2402 cfqg_stats_update_dispatch(cfqq
->cfqg
, blk_rq_bytes(rq
), rq
->cmd_flags
);
2406 * return expired entry, or NULL to just start from scratch in rbtree
2408 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2410 struct request
*rq
= NULL
;
2412 if (cfq_cfqq_fifo_expire(cfqq
))
2415 cfq_mark_cfqq_fifo_expire(cfqq
);
2417 if (list_empty(&cfqq
->fifo
))
2420 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2421 if (time_before(jiffies
, rq_fifo_time(rq
)))
2424 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2429 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2431 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2433 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2435 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2439 * Must be called with the queue_lock held.
2441 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2443 int process_refs
, io_refs
;
2445 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2446 process_refs
= cfqq
->ref
- io_refs
;
2447 BUG_ON(process_refs
< 0);
2448 return process_refs
;
2451 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2453 int process_refs
, new_process_refs
;
2454 struct cfq_queue
*__cfqq
;
2457 * If there are no process references on the new_cfqq, then it is
2458 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2459 * chain may have dropped their last reference (not just their
2460 * last process reference).
2462 if (!cfqq_process_refs(new_cfqq
))
2465 /* Avoid a circular list and skip interim queue merges */
2466 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2472 process_refs
= cfqq_process_refs(cfqq
);
2473 new_process_refs
= cfqq_process_refs(new_cfqq
);
2475 * If the process for the cfqq has gone away, there is no
2476 * sense in merging the queues.
2478 if (process_refs
== 0 || new_process_refs
== 0)
2482 * Merge in the direction of the lesser amount of work.
2484 if (new_process_refs
>= process_refs
) {
2485 cfqq
->new_cfqq
= new_cfqq
;
2486 new_cfqq
->ref
+= process_refs
;
2488 new_cfqq
->new_cfqq
= cfqq
;
2489 cfqq
->ref
+= new_process_refs
;
2493 static enum wl_type_t
cfq_choose_wl_type(struct cfq_data
*cfqd
,
2494 struct cfq_group
*cfqg
, enum wl_class_t wl_class
)
2496 struct cfq_queue
*queue
;
2498 bool key_valid
= false;
2499 unsigned long lowest_key
= 0;
2500 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2502 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2503 /* select the one with lowest rb_key */
2504 queue
= cfq_rb_first(st_for(cfqg
, wl_class
, i
));
2506 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2507 lowest_key
= queue
->rb_key
;
2517 choose_wl_class_and_type(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2521 struct cfq_rb_root
*st
;
2522 unsigned group_slice
;
2523 enum wl_class_t original_class
= cfqd
->serving_wl_class
;
2525 /* Choose next priority. RT > BE > IDLE */
2526 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2527 cfqd
->serving_wl_class
= RT_WORKLOAD
;
2528 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2529 cfqd
->serving_wl_class
= BE_WORKLOAD
;
2531 cfqd
->serving_wl_class
= IDLE_WORKLOAD
;
2532 cfqd
->workload_expires
= jiffies
+ 1;
2536 if (original_class
!= cfqd
->serving_wl_class
)
2540 * For RT and BE, we have to choose also the type
2541 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2544 st
= st_for(cfqg
, cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2548 * check workload expiration, and that we still have other queues ready
2550 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2554 /* otherwise select new workload type */
2555 cfqd
->serving_wl_type
= cfq_choose_wl_type(cfqd
, cfqg
,
2556 cfqd
->serving_wl_class
);
2557 st
= st_for(cfqg
, cfqd
->serving_wl_class
, cfqd
->serving_wl_type
);
2561 * the workload slice is computed as a fraction of target latency
2562 * proportional to the number of queues in that workload, over
2563 * all the queues in the same priority class
2565 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2567 slice
= group_slice
* count
/
2568 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_wl_class
],
2569 cfq_group_busy_queues_wl(cfqd
->serving_wl_class
, cfqd
,
2572 if (cfqd
->serving_wl_type
== ASYNC_WORKLOAD
) {
2576 * Async queues are currently system wide. Just taking
2577 * proportion of queues with-in same group will lead to higher
2578 * async ratio system wide as generally root group is going
2579 * to have higher weight. A more accurate thing would be to
2580 * calculate system wide asnc/sync ratio.
2582 tmp
= cfqd
->cfq_target_latency
*
2583 cfqg_busy_async_queues(cfqd
, cfqg
);
2584 tmp
= tmp
/cfqd
->busy_queues
;
2585 slice
= min_t(unsigned, slice
, tmp
);
2587 /* async workload slice is scaled down according to
2588 * the sync/async slice ratio. */
2589 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2591 /* sync workload slice is at least 2 * cfq_slice_idle */
2592 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2594 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2595 cfq_log(cfqd
, "workload slice:%d", slice
);
2596 cfqd
->workload_expires
= jiffies
+ slice
;
2599 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2601 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2602 struct cfq_group
*cfqg
;
2604 if (RB_EMPTY_ROOT(&st
->rb
))
2606 cfqg
= cfq_rb_first_group(st
);
2607 update_min_vdisktime(st
);
2611 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2613 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2615 cfqd
->serving_group
= cfqg
;
2617 /* Restore the workload type data */
2618 if (cfqg
->saved_wl_slice
) {
2619 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_wl_slice
;
2620 cfqd
->serving_wl_type
= cfqg
->saved_wl_type
;
2621 cfqd
->serving_wl_class
= cfqg
->saved_wl_class
;
2623 cfqd
->workload_expires
= jiffies
- 1;
2625 choose_wl_class_and_type(cfqd
, cfqg
);
2629 * Select a queue for service. If we have a current active queue,
2630 * check whether to continue servicing it, or retrieve and set a new one.
2632 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2634 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2636 cfqq
= cfqd
->active_queue
;
2640 if (!cfqd
->rq_queued
)
2644 * We were waiting for group to get backlogged. Expire the queue
2646 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2650 * The active queue has run out of time, expire it and select new.
2652 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2654 * If slice had not expired at the completion of last request
2655 * we might not have turned on wait_busy flag. Don't expire
2656 * the queue yet. Allow the group to get backlogged.
2658 * The very fact that we have used the slice, that means we
2659 * have been idling all along on this queue and it should be
2660 * ok to wait for this request to complete.
2662 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2663 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2667 goto check_group_idle
;
2671 * The active queue has requests and isn't expired, allow it to
2674 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2678 * If another queue has a request waiting within our mean seek
2679 * distance, let it run. The expire code will check for close
2680 * cooperators and put the close queue at the front of the service
2681 * tree. If possible, merge the expiring queue with the new cfqq.
2683 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2685 if (!cfqq
->new_cfqq
)
2686 cfq_setup_merge(cfqq
, new_cfqq
);
2691 * No requests pending. If the active queue still has requests in
2692 * flight or is idling for a new request, allow either of these
2693 * conditions to happen (or time out) before selecting a new queue.
2695 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2701 * This is a deep seek queue, but the device is much faster than
2702 * the queue can deliver, don't idle
2704 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2705 (cfq_cfqq_slice_new(cfqq
) ||
2706 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2707 cfq_clear_cfqq_deep(cfqq
);
2708 cfq_clear_cfqq_idle_window(cfqq
);
2711 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2717 * If group idle is enabled and there are requests dispatched from
2718 * this group, wait for requests to complete.
2721 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2722 cfqq
->cfqg
->dispatched
&&
2723 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2729 cfq_slice_expired(cfqd
, 0);
2732 * Current queue expired. Check if we have to switch to a new
2736 cfq_choose_cfqg(cfqd
);
2738 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2743 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2747 while (cfqq
->next_rq
) {
2748 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2752 BUG_ON(!list_empty(&cfqq
->fifo
));
2754 /* By default cfqq is not expired if it is empty. Do it explicitly */
2755 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2760 * Drain our current requests. Used for barriers and when switching
2761 * io schedulers on-the-fly.
2763 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2765 struct cfq_queue
*cfqq
;
2768 /* Expire the timeslice of the current active queue first */
2769 cfq_slice_expired(cfqd
, 0);
2770 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2771 __cfq_set_active_queue(cfqd
, cfqq
);
2772 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2775 BUG_ON(cfqd
->busy_queues
);
2777 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2781 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2782 struct cfq_queue
*cfqq
)
2784 /* the queue hasn't finished any request, can't estimate */
2785 if (cfq_cfqq_slice_new(cfqq
))
2787 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2794 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2796 unsigned int max_dispatch
;
2799 * Drain async requests before we start sync IO
2801 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2805 * If this is an async queue and we have sync IO in flight, let it wait
2807 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2810 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2811 if (cfq_class_idle(cfqq
))
2815 * Does this cfqq already have too much IO in flight?
2817 if (cfqq
->dispatched
>= max_dispatch
) {
2818 bool promote_sync
= false;
2820 * idle queue must always only have a single IO in flight
2822 if (cfq_class_idle(cfqq
))
2826 * If there is only one sync queue
2827 * we can ignore async queue here and give the sync
2828 * queue no dispatch limit. The reason is a sync queue can
2829 * preempt async queue, limiting the sync queue doesn't make
2830 * sense. This is useful for aiostress test.
2832 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2833 promote_sync
= true;
2836 * We have other queues, don't allow more IO from this one
2838 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2843 * Sole queue user, no limit
2845 if (cfqd
->busy_queues
== 1 || promote_sync
)
2849 * Normally we start throttling cfqq when cfq_quantum/2
2850 * requests have been dispatched. But we can drive
2851 * deeper queue depths at the beginning of slice
2852 * subjected to upper limit of cfq_quantum.
2854 max_dispatch
= cfqd
->cfq_quantum
;
2858 * Async queues must wait a bit before being allowed dispatch.
2859 * We also ramp up the dispatch depth gradually for async IO,
2860 * based on the last sync IO we serviced
2862 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2863 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2866 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2867 if (!depth
&& !cfqq
->dispatched
)
2869 if (depth
< max_dispatch
)
2870 max_dispatch
= depth
;
2874 * If we're below the current max, allow a dispatch
2876 return cfqq
->dispatched
< max_dispatch
;
2880 * Dispatch a request from cfqq, moving them to the request queue
2883 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2887 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2889 if (!cfq_may_dispatch(cfqd
, cfqq
))
2893 * follow expired path, else get first next available
2895 rq
= cfq_check_fifo(cfqq
);
2900 * insert request into driver dispatch list
2902 cfq_dispatch_insert(cfqd
->queue
, rq
);
2904 if (!cfqd
->active_cic
) {
2905 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
2907 atomic_long_inc(&cic
->icq
.ioc
->refcount
);
2908 cfqd
->active_cic
= cic
;
2915 * Find the cfqq that we need to service and move a request from that to the
2918 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2920 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2921 struct cfq_queue
*cfqq
;
2923 if (!cfqd
->busy_queues
)
2926 if (unlikely(force
))
2927 return cfq_forced_dispatch(cfqd
);
2929 cfqq
= cfq_select_queue(cfqd
);
2934 * Dispatch a request from this cfqq, if it is allowed
2936 if (!cfq_dispatch_request(cfqd
, cfqq
))
2939 cfqq
->slice_dispatch
++;
2940 cfq_clear_cfqq_must_dispatch(cfqq
);
2943 * expire an async queue immediately if it has used up its slice. idle
2944 * queue always expire after 1 dispatch round.
2946 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2947 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2948 cfq_class_idle(cfqq
))) {
2949 cfqq
->slice_end
= jiffies
+ 1;
2950 cfq_slice_expired(cfqd
, 0);
2953 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2958 * task holds one reference to the queue, dropped when task exits. each rq
2959 * in-flight on this queue also holds a reference, dropped when rq is freed.
2961 * Each cfq queue took a reference on the parent group. Drop it now.
2962 * queue lock must be held here.
2964 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2966 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2967 struct cfq_group
*cfqg
;
2969 BUG_ON(cfqq
->ref
<= 0);
2975 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2976 BUG_ON(rb_first(&cfqq
->sort_list
));
2977 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2980 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2981 __cfq_slice_expired(cfqd
, cfqq
, 0);
2982 cfq_schedule_dispatch(cfqd
);
2985 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2986 kmem_cache_free(cfq_pool
, cfqq
);
2990 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2992 struct cfq_queue
*__cfqq
, *next
;
2995 * If this queue was scheduled to merge with another queue, be
2996 * sure to drop the reference taken on that queue (and others in
2997 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2999 __cfqq
= cfqq
->new_cfqq
;
3001 if (__cfqq
== cfqq
) {
3002 WARN(1, "cfqq->new_cfqq loop detected\n");
3005 next
= __cfqq
->new_cfqq
;
3006 cfq_put_queue(__cfqq
);
3011 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3013 if (unlikely(cfqq
== cfqd
->active_queue
)) {
3014 __cfq_slice_expired(cfqd
, cfqq
, 0);
3015 cfq_schedule_dispatch(cfqd
);
3018 cfq_put_cooperator(cfqq
);
3020 cfq_put_queue(cfqq
);
3023 static void cfq_init_icq(struct io_cq
*icq
)
3025 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3027 cic
->ttime
.last_end_request
= jiffies
;
3030 static void cfq_exit_icq(struct io_cq
*icq
)
3032 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
3033 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3035 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
3036 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
3037 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
3040 if (cic
->cfqq
[BLK_RW_SYNC
]) {
3041 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
3042 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
3046 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct cfq_io_cq
*cic
)
3048 struct task_struct
*tsk
= current
;
3051 if (!cfq_cfqq_prio_changed(cfqq
))
3054 ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3055 switch (ioprio_class
) {
3057 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
3058 case IOPRIO_CLASS_NONE
:
3060 * no prio set, inherit CPU scheduling settings
3062 cfqq
->ioprio
= task_nice_ioprio(tsk
);
3063 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
3065 case IOPRIO_CLASS_RT
:
3066 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3067 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
3069 case IOPRIO_CLASS_BE
:
3070 cfqq
->ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3071 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3073 case IOPRIO_CLASS_IDLE
:
3074 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
3076 cfq_clear_cfqq_idle_window(cfqq
);
3081 * keep track of original prio settings in case we have to temporarily
3082 * elevate the priority of this queue
3084 cfqq
->org_ioprio
= cfqq
->ioprio
;
3085 cfq_clear_cfqq_prio_changed(cfqq
);
3088 static void check_ioprio_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3090 int ioprio
= cic
->icq
.ioc
->ioprio
;
3091 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3092 struct cfq_queue
*cfqq
;
3095 * Check whether ioprio has changed. The condition may trigger
3096 * spuriously on a newly created cic but there's no harm.
3098 if (unlikely(!cfqd
) || likely(cic
->ioprio
== ioprio
))
3101 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
3103 struct cfq_queue
*new_cfqq
;
3104 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
, bio
,
3107 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
3108 cfq_put_queue(cfqq
);
3112 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
3114 cfq_mark_cfqq_prio_changed(cfqq
);
3116 cic
->ioprio
= ioprio
;
3119 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3120 pid_t pid
, bool is_sync
)
3122 RB_CLEAR_NODE(&cfqq
->rb_node
);
3123 RB_CLEAR_NODE(&cfqq
->p_node
);
3124 INIT_LIST_HEAD(&cfqq
->fifo
);
3129 cfq_mark_cfqq_prio_changed(cfqq
);
3132 if (!cfq_class_idle(cfqq
))
3133 cfq_mark_cfqq_idle_window(cfqq
);
3134 cfq_mark_cfqq_sync(cfqq
);
3139 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3140 static void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
)
3142 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
3143 struct cfq_queue
*sync_cfqq
;
3147 id
= bio_blkcg(bio
)->id
;
3151 * Check whether blkcg has changed. The condition may trigger
3152 * spuriously on a newly created cic but there's no harm.
3154 if (unlikely(!cfqd
) || likely(cic
->blkcg_id
== id
))
3157 sync_cfqq
= cic_to_cfqq(cic
, 1);
3160 * Drop reference to sync queue. A new sync queue will be
3161 * assigned in new group upon arrival of a fresh request.
3163 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
3164 cic_set_cfqq(cic
, NULL
, 1);
3165 cfq_put_queue(sync_cfqq
);
3171 static inline void check_blkcg_changed(struct cfq_io_cq
*cic
, struct bio
*bio
) { }
3172 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
3174 static struct cfq_queue
*
3175 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3176 struct bio
*bio
, gfp_t gfp_mask
)
3178 struct blkcg
*blkcg
;
3179 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
3180 struct cfq_group
*cfqg
;
3185 blkcg
= bio_blkcg(bio
);
3186 cfqg
= cfq_lookup_create_cfqg(cfqd
, blkcg
);
3187 cfqq
= cic_to_cfqq(cic
, is_sync
);
3190 * Always try a new alloc if we fell back to the OOM cfqq
3191 * originally, since it should just be a temporary situation.
3193 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3198 } else if (gfp_mask
& __GFP_WAIT
) {
3200 spin_unlock_irq(cfqd
->queue
->queue_lock
);
3201 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
3202 gfp_mask
| __GFP_ZERO
,
3204 spin_lock_irq(cfqd
->queue
->queue_lock
);
3208 cfqq
= kmem_cache_alloc_node(cfq_pool
,
3209 gfp_mask
| __GFP_ZERO
,
3214 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
3215 cfq_init_prio_data(cfqq
, cic
);
3216 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
3217 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
3219 cfqq
= &cfqd
->oom_cfqq
;
3223 kmem_cache_free(cfq_pool
, new_cfqq
);
3229 static struct cfq_queue
**
3230 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
3232 switch (ioprio_class
) {
3233 case IOPRIO_CLASS_RT
:
3234 return &cfqd
->async_cfqq
[0][ioprio
];
3235 case IOPRIO_CLASS_NONE
:
3236 ioprio
= IOPRIO_NORM
;
3238 case IOPRIO_CLASS_BE
:
3239 return &cfqd
->async_cfqq
[1][ioprio
];
3240 case IOPRIO_CLASS_IDLE
:
3241 return &cfqd
->async_idle_cfqq
;
3247 static struct cfq_queue
*
3248 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct cfq_io_cq
*cic
,
3249 struct bio
*bio
, gfp_t gfp_mask
)
3251 const int ioprio_class
= IOPRIO_PRIO_CLASS(cic
->ioprio
);
3252 const int ioprio
= IOPRIO_PRIO_DATA(cic
->ioprio
);
3253 struct cfq_queue
**async_cfqq
= NULL
;
3254 struct cfq_queue
*cfqq
= NULL
;
3257 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
3262 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3265 * pin the queue now that it's allocated, scheduler exit will prune it
3267 if (!is_sync
&& !(*async_cfqq
)) {
3277 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3279 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3280 elapsed
= min(elapsed
, 2UL * slice_idle
);
3282 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3283 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3284 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3288 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3289 struct cfq_io_cq
*cic
)
3291 if (cfq_cfqq_sync(cfqq
)) {
3292 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3293 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3294 cfqd
->cfq_slice_idle
);
3296 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3297 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3302 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3306 sector_t n_sec
= blk_rq_sectors(rq
);
3307 if (cfqq
->last_request_pos
) {
3308 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3309 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3311 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3314 cfqq
->seek_history
<<= 1;
3315 if (blk_queue_nonrot(cfqd
->queue
))
3316 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3318 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3322 * Disable idle window if the process thinks too long or seeks so much that
3326 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3327 struct cfq_io_cq
*cic
)
3329 int old_idle
, enable_idle
;
3332 * Don't idle for async or idle io prio class
3334 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3337 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3339 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3340 cfq_mark_cfqq_deep(cfqq
);
3342 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3344 else if (!atomic_read(&cic
->icq
.ioc
->active_ref
) ||
3345 !cfqd
->cfq_slice_idle
||
3346 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3348 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3349 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3355 if (old_idle
!= enable_idle
) {
3356 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3358 cfq_mark_cfqq_idle_window(cfqq
);
3360 cfq_clear_cfqq_idle_window(cfqq
);
3365 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3366 * no or if we aren't sure, a 1 will cause a preempt.
3369 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3372 struct cfq_queue
*cfqq
;
3374 cfqq
= cfqd
->active_queue
;
3378 if (cfq_class_idle(new_cfqq
))
3381 if (cfq_class_idle(cfqq
))
3385 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3387 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3391 * if the new request is sync, but the currently running queue is
3392 * not, let the sync request have priority.
3394 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3397 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3400 if (cfq_slice_used(cfqq
))
3403 /* Allow preemption only if we are idling on sync-noidle tree */
3404 if (cfqd
->serving_wl_type
== SYNC_NOIDLE_WORKLOAD
&&
3405 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3406 new_cfqq
->service_tree
->count
== 2 &&
3407 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3411 * So both queues are sync. Let the new request get disk time if
3412 * it's a metadata request and the current queue is doing regular IO.
3414 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3418 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3420 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3423 /* An idle queue should not be idle now for some reason */
3424 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3427 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3431 * if this request is as-good as one we would expect from the
3432 * current cfqq, let it preempt
3434 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3441 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3442 * let it have half of its nominal slice.
3444 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3446 enum wl_type_t old_type
= cfqq_type(cfqd
->active_queue
);
3448 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3449 cfq_slice_expired(cfqd
, 1);
3452 * workload type is changed, don't save slice, otherwise preempt
3455 if (old_type
!= cfqq_type(cfqq
))
3456 cfqq
->cfqg
->saved_wl_slice
= 0;
3459 * Put the new queue at the front of the of the current list,
3460 * so we know that it will be selected next.
3462 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3464 cfq_service_tree_add(cfqd
, cfqq
, 1);
3466 cfqq
->slice_end
= 0;
3467 cfq_mark_cfqq_slice_new(cfqq
);
3471 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3472 * something we should do about it
3475 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3478 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3481 if (rq
->cmd_flags
& REQ_PRIO
)
3482 cfqq
->prio_pending
++;
3484 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3485 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3486 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3488 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3490 if (cfqq
== cfqd
->active_queue
) {
3492 * Remember that we saw a request from this process, but
3493 * don't start queuing just yet. Otherwise we risk seeing lots
3494 * of tiny requests, because we disrupt the normal plugging
3495 * and merging. If the request is already larger than a single
3496 * page, let it rip immediately. For that case we assume that
3497 * merging is already done. Ditto for a busy system that
3498 * has other work pending, don't risk delaying until the
3499 * idle timer unplug to continue working.
3501 if (cfq_cfqq_wait_request(cfqq
)) {
3502 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3503 cfqd
->busy_queues
> 1) {
3504 cfq_del_timer(cfqd
, cfqq
);
3505 cfq_clear_cfqq_wait_request(cfqq
);
3506 __blk_run_queue(cfqd
->queue
);
3508 cfqg_stats_update_idle_time(cfqq
->cfqg
);
3509 cfq_mark_cfqq_must_dispatch(cfqq
);
3512 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3514 * not the active queue - expire current slice if it is
3515 * idle and has expired it's mean thinktime or this new queue
3516 * has some old slice time left and is of higher priority or
3517 * this new queue is RT and the current one is BE
3519 cfq_preempt_queue(cfqd
, cfqq
);
3520 __blk_run_queue(cfqd
->queue
);
3524 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3526 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3527 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3529 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3530 cfq_init_prio_data(cfqq
, RQ_CIC(rq
));
3532 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3533 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3535 cfqg_stats_update_io_add(RQ_CFQG(rq
), cfqd
->serving_group
,
3537 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3541 * Update hw_tag based on peak queue depth over 50 samples under
3544 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3546 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3548 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3549 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3551 if (cfqd
->hw_tag
== 1)
3554 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3555 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3559 * If active queue hasn't enough requests and can idle, cfq might not
3560 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3563 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3564 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3565 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3568 if (cfqd
->hw_tag_samples
++ < 50)
3571 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3577 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3579 struct cfq_io_cq
*cic
= cfqd
->active_cic
;
3581 /* If the queue already has requests, don't wait */
3582 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3585 /* If there are other queues in the group, don't wait */
3586 if (cfqq
->cfqg
->nr_cfqq
> 1)
3589 /* the only queue in the group, but think time is big */
3590 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3593 if (cfq_slice_used(cfqq
))
3596 /* if slice left is less than think time, wait busy */
3597 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3598 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3602 * If think times is less than a jiffy than ttime_mean=0 and above
3603 * will not be true. It might happen that slice has not expired yet
3604 * but will expire soon (4-5 ns) during select_queue(). To cover the
3605 * case where think time is less than a jiffy, mark the queue wait
3606 * busy if only 1 jiffy is left in the slice.
3608 if (cfqq
->slice_end
- jiffies
== 1)
3614 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3616 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3617 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3618 const int sync
= rq_is_sync(rq
);
3622 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3623 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3625 cfq_update_hw_tag(cfqd
);
3627 WARN_ON(!cfqd
->rq_in_driver
);
3628 WARN_ON(!cfqq
->dispatched
);
3629 cfqd
->rq_in_driver
--;
3631 (RQ_CFQG(rq
))->dispatched
--;
3632 cfqg_stats_update_completion(cfqq
->cfqg
, rq_start_time_ns(rq
),
3633 rq_io_start_time_ns(rq
), rq
->cmd_flags
);
3635 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3638 struct cfq_rb_root
*st
;
3640 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3642 if (cfq_cfqq_on_rr(cfqq
))
3643 st
= cfqq
->service_tree
;
3645 st
= st_for(cfqq
->cfqg
, cfqq_class(cfqq
),
3648 st
->ttime
.last_end_request
= now
;
3649 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3650 cfqd
->last_delayed_sync
= now
;
3653 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3654 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3658 * If this is the active queue, check if it needs to be expired,
3659 * or if we want to idle in case it has no pending requests.
3661 if (cfqd
->active_queue
== cfqq
) {
3662 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3664 if (cfq_cfqq_slice_new(cfqq
)) {
3665 cfq_set_prio_slice(cfqd
, cfqq
);
3666 cfq_clear_cfqq_slice_new(cfqq
);
3670 * Should we wait for next request to come in before we expire
3673 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3674 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3675 if (!cfqd
->cfq_slice_idle
)
3676 extend_sl
= cfqd
->cfq_group_idle
;
3677 cfqq
->slice_end
= jiffies
+ extend_sl
;
3678 cfq_mark_cfqq_wait_busy(cfqq
);
3679 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3683 * Idling is not enabled on:
3685 * - idle-priority queues
3687 * - queues with still some requests queued
3688 * - when there is a close cooperator
3690 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3691 cfq_slice_expired(cfqd
, 1);
3692 else if (sync
&& cfqq_empty
&&
3693 !cfq_close_cooperator(cfqd
, cfqq
)) {
3694 cfq_arm_slice_timer(cfqd
);
3698 if (!cfqd
->rq_in_driver
)
3699 cfq_schedule_dispatch(cfqd
);
3702 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3704 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3705 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3706 return ELV_MQUEUE_MUST
;
3709 return ELV_MQUEUE_MAY
;
3712 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3714 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3715 struct task_struct
*tsk
= current
;
3716 struct cfq_io_cq
*cic
;
3717 struct cfq_queue
*cfqq
;
3720 * don't force setup of a queue from here, as a call to may_queue
3721 * does not necessarily imply that a request actually will be queued.
3722 * so just lookup a possibly existing queue, or return 'may queue'
3725 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3727 return ELV_MQUEUE_MAY
;
3729 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3731 cfq_init_prio_data(cfqq
, cic
);
3733 return __cfq_may_queue(cfqq
);
3736 return ELV_MQUEUE_MAY
;
3740 * queue lock held here
3742 static void cfq_put_request(struct request
*rq
)
3744 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3747 const int rw
= rq_data_dir(rq
);
3749 BUG_ON(!cfqq
->allocated
[rw
]);
3750 cfqq
->allocated
[rw
]--;
3752 /* Put down rq reference on cfqg */
3753 cfqg_put(RQ_CFQG(rq
));
3754 rq
->elv
.priv
[0] = NULL
;
3755 rq
->elv
.priv
[1] = NULL
;
3757 cfq_put_queue(cfqq
);
3761 static struct cfq_queue
*
3762 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_cq
*cic
,
3763 struct cfq_queue
*cfqq
)
3765 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3766 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3767 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3768 cfq_put_queue(cfqq
);
3769 return cic_to_cfqq(cic
, 1);
3773 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3774 * was the last process referring to said cfqq.
3776 static struct cfq_queue
*
3777 split_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
)
3779 if (cfqq_process_refs(cfqq
) == 1) {
3780 cfqq
->pid
= current
->pid
;
3781 cfq_clear_cfqq_coop(cfqq
);
3782 cfq_clear_cfqq_split_coop(cfqq
);
3786 cic_set_cfqq(cic
, NULL
, 1);
3788 cfq_put_cooperator(cfqq
);
3790 cfq_put_queue(cfqq
);
3794 * Allocate cfq data structures associated with this request.
3797 cfq_set_request(struct request_queue
*q
, struct request
*rq
, struct bio
*bio
,
3800 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3801 struct cfq_io_cq
*cic
= icq_to_cic(rq
->elv
.icq
);
3802 const int rw
= rq_data_dir(rq
);
3803 const bool is_sync
= rq_is_sync(rq
);
3804 struct cfq_queue
*cfqq
;
3806 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3808 spin_lock_irq(q
->queue_lock
);
3810 check_ioprio_changed(cic
, bio
);
3811 check_blkcg_changed(cic
, bio
);
3813 cfqq
= cic_to_cfqq(cic
, is_sync
);
3814 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3815 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
, bio
, gfp_mask
);
3816 cic_set_cfqq(cic
, cfqq
, is_sync
);
3819 * If the queue was seeky for too long, break it apart.
3821 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3822 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3823 cfqq
= split_cfqq(cic
, cfqq
);
3829 * Check to see if this queue is scheduled to merge with
3830 * another, closely cooperating queue. The merging of
3831 * queues happens here as it must be done in process context.
3832 * The reference on new_cfqq was taken in merge_cfqqs.
3835 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3838 cfqq
->allocated
[rw
]++;
3841 cfqg_get(cfqq
->cfqg
);
3842 rq
->elv
.priv
[0] = cfqq
;
3843 rq
->elv
.priv
[1] = cfqq
->cfqg
;
3844 spin_unlock_irq(q
->queue_lock
);
3848 static void cfq_kick_queue(struct work_struct
*work
)
3850 struct cfq_data
*cfqd
=
3851 container_of(work
, struct cfq_data
, unplug_work
);
3852 struct request_queue
*q
= cfqd
->queue
;
3854 spin_lock_irq(q
->queue_lock
);
3855 __blk_run_queue(cfqd
->queue
);
3856 spin_unlock_irq(q
->queue_lock
);
3860 * Timer running if the active_queue is currently idling inside its time slice
3862 static void cfq_idle_slice_timer(unsigned long data
)
3864 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3865 struct cfq_queue
*cfqq
;
3866 unsigned long flags
;
3869 cfq_log(cfqd
, "idle timer fired");
3871 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3873 cfqq
= cfqd
->active_queue
;
3878 * We saw a request before the queue expired, let it through
3880 if (cfq_cfqq_must_dispatch(cfqq
))
3886 if (cfq_slice_used(cfqq
))
3890 * only expire and reinvoke request handler, if there are
3891 * other queues with pending requests
3893 if (!cfqd
->busy_queues
)
3897 * not expired and it has a request pending, let it dispatch
3899 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3903 * Queue depth flag is reset only when the idle didn't succeed
3905 cfq_clear_cfqq_deep(cfqq
);
3908 cfq_slice_expired(cfqd
, timed_out
);
3910 cfq_schedule_dispatch(cfqd
);
3912 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3915 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3917 del_timer_sync(&cfqd
->idle_slice_timer
);
3918 cancel_work_sync(&cfqd
->unplug_work
);
3921 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3925 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3926 if (cfqd
->async_cfqq
[0][i
])
3927 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3928 if (cfqd
->async_cfqq
[1][i
])
3929 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3932 if (cfqd
->async_idle_cfqq
)
3933 cfq_put_queue(cfqd
->async_idle_cfqq
);
3936 static void cfq_exit_queue(struct elevator_queue
*e
)
3938 struct cfq_data
*cfqd
= e
->elevator_data
;
3939 struct request_queue
*q
= cfqd
->queue
;
3941 cfq_shutdown_timer_wq(cfqd
);
3943 spin_lock_irq(q
->queue_lock
);
3945 if (cfqd
->active_queue
)
3946 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3948 cfq_put_async_queues(cfqd
);
3950 spin_unlock_irq(q
->queue_lock
);
3952 cfq_shutdown_timer_wq(cfqd
);
3954 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3955 blkcg_deactivate_policy(q
, &blkcg_policy_cfq
);
3957 kfree(cfqd
->root_group
);
3962 static int cfq_init_queue(struct request_queue
*q
)
3964 struct cfq_data
*cfqd
;
3965 struct blkcg_gq
*blkg __maybe_unused
;
3968 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3973 q
->elevator
->elevator_data
= cfqd
;
3975 /* Init root service tree */
3976 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3978 /* Init root group and prefer root group over other groups by default */
3979 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3980 ret
= blkcg_activate_policy(q
, &blkcg_policy_cfq
);
3984 cfqd
->root_group
= blkg_to_cfqg(q
->root_blkg
);
3987 cfqd
->root_group
= kzalloc_node(sizeof(*cfqd
->root_group
),
3988 GFP_KERNEL
, cfqd
->queue
->node
);
3989 if (!cfqd
->root_group
)
3992 cfq_init_cfqg_base(cfqd
->root_group
);
3994 cfqd
->root_group
->weight
= 2 * CFQ_WEIGHT_DEFAULT
;
3997 * Not strictly needed (since RB_ROOT just clears the node and we
3998 * zeroed cfqd on alloc), but better be safe in case someone decides
3999 * to add magic to the rb code
4001 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
4002 cfqd
->prio_trees
[i
] = RB_ROOT
;
4005 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4006 * Grab a permanent reference to it, so that the normal code flow
4007 * will not attempt to free it. oom_cfqq is linked to root_group
4008 * but shouldn't hold a reference as it'll never be unlinked. Lose
4009 * the reference from linking right away.
4011 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
4012 cfqd
->oom_cfqq
.ref
++;
4014 spin_lock_irq(q
->queue_lock
);
4015 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, cfqd
->root_group
);
4016 cfqg_put(cfqd
->root_group
);
4017 spin_unlock_irq(q
->queue_lock
);
4019 init_timer(&cfqd
->idle_slice_timer
);
4020 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
4021 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
4023 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
4025 cfqd
->cfq_quantum
= cfq_quantum
;
4026 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
4027 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
4028 cfqd
->cfq_back_max
= cfq_back_max
;
4029 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
4030 cfqd
->cfq_slice
[0] = cfq_slice_async
;
4031 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
4032 cfqd
->cfq_target_latency
= cfq_target_latency
;
4033 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
4034 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
4035 cfqd
->cfq_group_idle
= cfq_group_idle
;
4036 cfqd
->cfq_latency
= 1;
4039 * we optimistically start assuming sync ops weren't delayed in last
4040 * second, in order to have larger depth for async operations.
4042 cfqd
->last_delayed_sync
= jiffies
- HZ
;
4051 * sysfs parts below -->
4054 cfq_var_show(unsigned int var
, char *page
)
4056 return sprintf(page
, "%d\n", var
);
4060 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4062 char *p
= (char *) page
;
4064 *var
= simple_strtoul(p
, &p
, 10);
4068 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4069 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4071 struct cfq_data *cfqd = e->elevator_data; \
4072 unsigned int __data = __VAR; \
4074 __data = jiffies_to_msecs(__data); \
4075 return cfq_var_show(__data, (page)); \
4077 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4078 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4079 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4080 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4081 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4082 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4083 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4084 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4085 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4086 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4087 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4088 SHOW_FUNCTION(cfq_target_latency_show
, cfqd
->cfq_target_latency
, 1);
4089 #undef SHOW_FUNCTION
4091 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4092 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4094 struct cfq_data *cfqd = e->elevator_data; \
4095 unsigned int __data; \
4096 int ret = cfq_var_store(&__data, (page), count); \
4097 if (__data < (MIN)) \
4099 else if (__data > (MAX)) \
4102 *(__PTR) = msecs_to_jiffies(__data); \
4104 *(__PTR) = __data; \
4107 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4108 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4110 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4112 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4113 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4115 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4116 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4117 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4118 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4119 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4121 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4122 STORE_FUNCTION(cfq_target_latency_store
, &cfqd
->cfq_target_latency
, 1, UINT_MAX
, 1);
4123 #undef STORE_FUNCTION
4125 #define CFQ_ATTR(name) \
4126 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4128 static struct elv_fs_entry cfq_attrs
[] = {
4130 CFQ_ATTR(fifo_expire_sync
),
4131 CFQ_ATTR(fifo_expire_async
),
4132 CFQ_ATTR(back_seek_max
),
4133 CFQ_ATTR(back_seek_penalty
),
4134 CFQ_ATTR(slice_sync
),
4135 CFQ_ATTR(slice_async
),
4136 CFQ_ATTR(slice_async_rq
),
4137 CFQ_ATTR(slice_idle
),
4138 CFQ_ATTR(group_idle
),
4139 CFQ_ATTR(low_latency
),
4140 CFQ_ATTR(target_latency
),
4144 static struct elevator_type iosched_cfq
= {
4146 .elevator_merge_fn
= cfq_merge
,
4147 .elevator_merged_fn
= cfq_merged_request
,
4148 .elevator_merge_req_fn
= cfq_merged_requests
,
4149 .elevator_allow_merge_fn
= cfq_allow_merge
,
4150 .elevator_bio_merged_fn
= cfq_bio_merged
,
4151 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4152 .elevator_add_req_fn
= cfq_insert_request
,
4153 .elevator_activate_req_fn
= cfq_activate_request
,
4154 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4155 .elevator_completed_req_fn
= cfq_completed_request
,
4156 .elevator_former_req_fn
= elv_rb_former_request
,
4157 .elevator_latter_req_fn
= elv_rb_latter_request
,
4158 .elevator_init_icq_fn
= cfq_init_icq
,
4159 .elevator_exit_icq_fn
= cfq_exit_icq
,
4160 .elevator_set_req_fn
= cfq_set_request
,
4161 .elevator_put_req_fn
= cfq_put_request
,
4162 .elevator_may_queue_fn
= cfq_may_queue
,
4163 .elevator_init_fn
= cfq_init_queue
,
4164 .elevator_exit_fn
= cfq_exit_queue
,
4166 .icq_size
= sizeof(struct cfq_io_cq
),
4167 .icq_align
= __alignof__(struct cfq_io_cq
),
4168 .elevator_attrs
= cfq_attrs
,
4169 .elevator_name
= "cfq",
4170 .elevator_owner
= THIS_MODULE
,
4173 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4174 static struct blkcg_policy blkcg_policy_cfq
= {
4175 .pd_size
= sizeof(struct cfq_group
),
4176 .cftypes
= cfq_blkcg_files
,
4178 .pd_init_fn
= cfq_pd_init
,
4179 .pd_reset_stats_fn
= cfq_pd_reset_stats
,
4183 static int __init
cfq_init(void)
4188 * could be 0 on HZ < 1000 setups
4190 if (!cfq_slice_async
)
4191 cfq_slice_async
= 1;
4192 if (!cfq_slice_idle
)
4195 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4196 if (!cfq_group_idle
)
4199 ret
= blkcg_policy_register(&blkcg_policy_cfq
);
4207 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
4211 ret
= elv_register(&iosched_cfq
);
4218 kmem_cache_destroy(cfq_pool
);
4220 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4221 blkcg_policy_unregister(&blkcg_policy_cfq
);
4226 static void __exit
cfq_exit(void)
4228 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4229 blkcg_policy_unregister(&blkcg_policy_cfq
);
4231 elv_unregister(&iosched_cfq
);
4232 kmem_cache_destroy(cfq_pool
);
4235 module_init(cfq_init
);
4236 module_exit(cfq_exit
);
4238 MODULE_AUTHOR("Jens Axboe");
4239 MODULE_LICENSE("GPL");
4240 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");