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@suse.de>
9 #include <linux/kernel.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/bio.h>
14 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/compiler.h>
19 #include <linux/hash.h>
20 #include <linux/rbtree.h>
21 #include <linux/mempool.h>
22 #include <linux/ioprio.h>
23 #include <linux/writeback.h>
28 static const int cfq_quantum
= 4; /* max queue in one round of service */
29 static const int cfq_queued
= 8; /* minimum rq allocate limit per-queue*/
30 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
31 static const int cfq_back_max
= 16 * 1024; /* maximum backwards seek, in KiB */
32 static const int cfq_back_penalty
= 2; /* penalty of a backwards seek */
34 static const int cfq_slice_sync
= HZ
/ 10;
35 static int cfq_slice_async
= HZ
/ 25;
36 static const int cfq_slice_async_rq
= 2;
37 static int cfq_slice_idle
= HZ
/ 100;
39 #define CFQ_IDLE_GRACE (HZ / 10)
40 #define CFQ_SLICE_SCALE (5)
42 #define CFQ_KEY_ASYNC (0)
43 #define CFQ_KEY_ANY (0xffff)
46 * disable queueing at the driver/hardware level
48 static const int cfq_max_depth
= 2;
51 * for the hash of cfqq inside the cfqd
53 #define CFQ_QHASH_SHIFT 6
54 #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
55 #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
58 * for the hash of crq inside the cfqq
60 #define CFQ_MHASH_SHIFT 6
61 #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
62 #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
63 #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
64 #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
65 #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
67 #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
68 #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
70 #define RQ_DATA(rq) (rq)->elevator_private
76 #define RB_EMPTY(node) ((node)->rb_node == NULL)
77 #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
78 #define RB_CLEAR(node) do { \
79 (node)->rb_parent = NULL; \
80 RB_CLEAR_COLOR((node)); \
81 (node)->rb_right = NULL; \
82 (node)->rb_left = NULL; \
84 #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
85 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
86 #define rq_rb_key(rq) (rq)->sector
88 static kmem_cache_t
*crq_pool
;
89 static kmem_cache_t
*cfq_pool
;
90 static kmem_cache_t
*cfq_ioc_pool
;
92 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
93 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
94 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
95 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
100 #define cfq_cfqq_dispatched(cfqq) \
101 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
103 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
105 #define cfq_cfqq_sync(cfqq) \
106 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
109 * Per block device queue structure
113 request_queue_t
*queue
;
116 * rr list of queues with requests and the count of them
118 struct list_head rr_list
[CFQ_PRIO_LISTS
];
119 struct list_head busy_rr
;
120 struct list_head cur_rr
;
121 struct list_head idle_rr
;
122 unsigned int busy_queues
;
125 * non-ordered list of empty cfqq's
127 struct list_head empty_list
;
132 struct hlist_head
*cfq_hash
;
135 * global crq hash for all queues
137 struct hlist_head
*crq_hash
;
139 unsigned int max_queued
;
146 * schedule slice state info
149 * idle window management
151 struct timer_list idle_slice_timer
;
152 struct work_struct unplug_work
;
154 struct cfq_queue
*active_queue
;
155 struct cfq_io_context
*active_cic
;
156 int cur_prio
, cur_end_prio
;
157 unsigned int dispatch_slice
;
159 struct timer_list idle_class_timer
;
161 sector_t last_sector
;
162 unsigned long last_end_request
;
164 unsigned int rq_starved
;
167 * tunables, see top of file
169 unsigned int cfq_quantum
;
170 unsigned int cfq_queued
;
171 unsigned int cfq_fifo_expire
[2];
172 unsigned int cfq_back_penalty
;
173 unsigned int cfq_back_max
;
174 unsigned int cfq_slice
[2];
175 unsigned int cfq_slice_async_rq
;
176 unsigned int cfq_slice_idle
;
177 unsigned int cfq_max_depth
;
181 * Per process-grouping structure
184 /* reference count */
186 /* parent cfq_data */
187 struct cfq_data
*cfqd
;
188 /* cfqq lookup hash */
189 struct hlist_node cfq_hash
;
192 /* on either rr or empty list of cfqd */
193 struct list_head cfq_list
;
194 /* sorted list of pending requests */
195 struct rb_root sort_list
;
196 /* if fifo isn't expired, next request to serve */
197 struct cfq_rq
*next_crq
;
198 /* requests queued in sort_list */
200 /* currently allocated requests */
202 /* fifo list of requests in sort_list */
203 struct list_head fifo
;
205 unsigned long slice_start
;
206 unsigned long slice_end
;
207 unsigned long slice_left
;
208 unsigned long service_last
;
210 /* number of requests that are on the dispatch list */
213 /* io prio of this group */
214 unsigned short ioprio
, org_ioprio
;
215 unsigned short ioprio_class
, org_ioprio_class
;
217 /* various state flags, see below */
222 struct rb_node rb_node
;
224 struct request
*request
;
225 struct hlist_node hash
;
227 struct cfq_queue
*cfq_queue
;
228 struct cfq_io_context
*io_context
;
230 unsigned int crq_flags
;
233 enum cfqq_state_flags
{
234 CFQ_CFQQ_FLAG_on_rr
= 0,
235 CFQ_CFQQ_FLAG_wait_request
,
236 CFQ_CFQQ_FLAG_must_alloc
,
237 CFQ_CFQQ_FLAG_must_alloc_slice
,
238 CFQ_CFQQ_FLAG_must_dispatch
,
239 CFQ_CFQQ_FLAG_fifo_expire
,
240 CFQ_CFQQ_FLAG_idle_window
,
241 CFQ_CFQQ_FLAG_prio_changed
,
244 #define CFQ_CFQQ_FNS(name) \
245 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
247 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
249 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
251 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
253 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
255 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
259 CFQ_CFQQ_FNS(wait_request
);
260 CFQ_CFQQ_FNS(must_alloc
);
261 CFQ_CFQQ_FNS(must_alloc_slice
);
262 CFQ_CFQQ_FNS(must_dispatch
);
263 CFQ_CFQQ_FNS(fifo_expire
);
264 CFQ_CFQQ_FNS(idle_window
);
265 CFQ_CFQQ_FNS(prio_changed
);
268 enum cfq_rq_state_flags
{
269 CFQ_CRQ_FLAG_is_sync
= 0,
272 #define CFQ_CRQ_FNS(name) \
273 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
275 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
277 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
279 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
281 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
283 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
286 CFQ_CRQ_FNS(is_sync
);
289 static struct cfq_queue
*cfq_find_cfq_hash(struct cfq_data
*, unsigned int, unsigned short);
290 static void cfq_dispatch_insert(request_queue_t
*, struct cfq_rq
*);
291 static void cfq_put_cfqd(struct cfq_data
*cfqd
);
293 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
296 * lots of deadline iosched dupes, can be abstracted later...
298 static inline void cfq_del_crq_hash(struct cfq_rq
*crq
)
300 hlist_del_init(&crq
->hash
);
303 static inline void cfq_add_crq_hash(struct cfq_data
*cfqd
, struct cfq_rq
*crq
)
305 const int hash_idx
= CFQ_MHASH_FN(rq_hash_key(crq
->request
));
307 hlist_add_head(&crq
->hash
, &cfqd
->crq_hash
[hash_idx
]);
310 static struct request
*cfq_find_rq_hash(struct cfq_data
*cfqd
, sector_t offset
)
312 struct hlist_head
*hash_list
= &cfqd
->crq_hash
[CFQ_MHASH_FN(offset
)];
313 struct hlist_node
*entry
, *next
;
315 hlist_for_each_safe(entry
, next
, hash_list
) {
316 struct cfq_rq
*crq
= list_entry_hash(entry
);
317 struct request
*__rq
= crq
->request
;
319 if (!rq_mergeable(__rq
)) {
320 cfq_del_crq_hash(crq
);
324 if (rq_hash_key(__rq
) == offset
)
332 * scheduler run of queue, if there are requests pending and no one in the
333 * driver that will restart queueing
335 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
337 if (cfqd
->busy_queues
)
338 kblockd_schedule_work(&cfqd
->unplug_work
);
341 static int cfq_queue_empty(request_queue_t
*q
)
343 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
345 return !cfqd
->busy_queues
;
349 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
350 * We choose the request that is closest to the head right now. Distance
351 * behind the head are penalized and only allowed to a certain extent.
353 static struct cfq_rq
*
354 cfq_choose_req(struct cfq_data
*cfqd
, struct cfq_rq
*crq1
, struct cfq_rq
*crq2
)
356 sector_t last
, s1
, s2
, d1
= 0, d2
= 0;
357 int r1_wrap
= 0, r2_wrap
= 0; /* requests are behind the disk head */
358 unsigned long back_max
;
360 if (crq1
== NULL
|| crq1
== crq2
)
365 if (cfq_crq_is_sync(crq1
) && !cfq_crq_is_sync(crq2
))
367 else if (cfq_crq_is_sync(crq2
) && !cfq_crq_is_sync(crq1
))
370 s1
= crq1
->request
->sector
;
371 s2
= crq2
->request
->sector
;
373 last
= cfqd
->last_sector
;
376 * by definition, 1KiB is 2 sectors
378 back_max
= cfqd
->cfq_back_max
* 2;
381 * Strict one way elevator _except_ in the case where we allow
382 * short backward seeks which are biased as twice the cost of a
383 * similar forward seek.
387 else if (s1
+ back_max
>= last
)
388 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
394 else if (s2
+ back_max
>= last
)
395 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
399 /* Found required data */
400 if (!r1_wrap
&& r2_wrap
)
402 else if (!r2_wrap
&& r1_wrap
)
404 else if (r1_wrap
&& r2_wrap
) {
405 /* both behind the head */
412 /* Both requests in front of the head */
426 * would be nice to take fifo expire time into account as well
428 static struct cfq_rq
*
429 cfq_find_next_crq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
432 struct cfq_rq
*crq_next
= NULL
, *crq_prev
= NULL
;
433 struct rb_node
*rbnext
, *rbprev
;
435 if (!(rbnext
= rb_next(&last
->rb_node
))) {
436 rbnext
= rb_first(&cfqq
->sort_list
);
437 if (rbnext
== &last
->rb_node
)
441 rbprev
= rb_prev(&last
->rb_node
);
444 crq_prev
= rb_entry_crq(rbprev
);
446 crq_next
= rb_entry_crq(rbnext
);
448 return cfq_choose_req(cfqd
, crq_next
, crq_prev
);
451 static void cfq_update_next_crq(struct cfq_rq
*crq
)
453 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
455 if (cfqq
->next_crq
== crq
)
456 cfqq
->next_crq
= cfq_find_next_crq(cfqq
->cfqd
, cfqq
, crq
);
459 static void cfq_resort_rr_list(struct cfq_queue
*cfqq
, int preempted
)
461 struct cfq_data
*cfqd
= cfqq
->cfqd
;
462 struct list_head
*list
, *entry
;
464 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
466 list_del(&cfqq
->cfq_list
);
468 if (cfq_class_rt(cfqq
))
469 list
= &cfqd
->cur_rr
;
470 else if (cfq_class_idle(cfqq
))
471 list
= &cfqd
->idle_rr
;
474 * if cfqq has requests in flight, don't allow it to be
475 * found in cfq_set_active_queue before it has finished them.
476 * this is done to increase fairness between a process that
477 * has lots of io pending vs one that only generates one
478 * sporadically or synchronously
480 if (cfq_cfqq_dispatched(cfqq
))
481 list
= &cfqd
->busy_rr
;
483 list
= &cfqd
->rr_list
[cfqq
->ioprio
];
487 * if queue was preempted, just add to front to be fair. busy_rr
490 if (preempted
|| list
== &cfqd
->busy_rr
) {
491 list_add(&cfqq
->cfq_list
, list
);
496 * sort by when queue was last serviced
499 while ((entry
= entry
->prev
) != list
) {
500 struct cfq_queue
*__cfqq
= list_entry_cfqq(entry
);
502 if (!__cfqq
->service_last
)
504 if (time_before(__cfqq
->service_last
, cfqq
->service_last
))
508 list_add(&cfqq
->cfq_list
, entry
);
512 * add to busy list of queues for service, trying to be fair in ordering
513 * the pending list according to last request service
516 cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
518 BUG_ON(cfq_cfqq_on_rr(cfqq
));
519 cfq_mark_cfqq_on_rr(cfqq
);
522 cfq_resort_rr_list(cfqq
, 0);
526 cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
528 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
529 cfq_clear_cfqq_on_rr(cfqq
);
530 list_move(&cfqq
->cfq_list
, &cfqd
->empty_list
);
532 BUG_ON(!cfqd
->busy_queues
);
537 * rb tree support functions
539 static inline void cfq_del_crq_rb(struct cfq_rq
*crq
)
541 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
542 struct cfq_data
*cfqd
= cfqq
->cfqd
;
543 const int sync
= cfq_crq_is_sync(crq
);
545 BUG_ON(!cfqq
->queued
[sync
]);
546 cfqq
->queued
[sync
]--;
548 cfq_update_next_crq(crq
);
550 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
551 RB_CLEAR_COLOR(&crq
->rb_node
);
553 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY(&cfqq
->sort_list
))
554 cfq_del_cfqq_rr(cfqd
, cfqq
);
557 static struct cfq_rq
*
558 __cfq_add_crq_rb(struct cfq_rq
*crq
)
560 struct rb_node
**p
= &crq
->cfq_queue
->sort_list
.rb_node
;
561 struct rb_node
*parent
= NULL
;
562 struct cfq_rq
*__crq
;
566 __crq
= rb_entry_crq(parent
);
568 if (crq
->rb_key
< __crq
->rb_key
)
570 else if (crq
->rb_key
> __crq
->rb_key
)
576 rb_link_node(&crq
->rb_node
, parent
, p
);
580 static void cfq_add_crq_rb(struct cfq_rq
*crq
)
582 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
583 struct cfq_data
*cfqd
= cfqq
->cfqd
;
584 struct request
*rq
= crq
->request
;
585 struct cfq_rq
*__alias
;
587 crq
->rb_key
= rq_rb_key(rq
);
588 cfqq
->queued
[cfq_crq_is_sync(crq
)]++;
591 * looks a little odd, but the first insert might return an alias.
592 * if that happens, put the alias on the dispatch list
594 while ((__alias
= __cfq_add_crq_rb(crq
)) != NULL
)
595 cfq_dispatch_insert(cfqd
->queue
, __alias
);
597 rb_insert_color(&crq
->rb_node
, &cfqq
->sort_list
);
599 if (!cfq_cfqq_on_rr(cfqq
))
600 cfq_add_cfqq_rr(cfqd
, cfqq
);
603 * check if this request is a better next-serve candidate
605 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
609 cfq_reposition_crq_rb(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
611 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
612 cfqq
->queued
[cfq_crq_is_sync(crq
)]--;
617 static struct request
*cfq_find_rq_rb(struct cfq_data
*cfqd
, sector_t sector
)
620 struct cfq_queue
*cfqq
= cfq_find_cfq_hash(cfqd
, current
->pid
, CFQ_KEY_ANY
);
626 n
= cfqq
->sort_list
.rb_node
;
628 struct cfq_rq
*crq
= rb_entry_crq(n
);
630 if (sector
< crq
->rb_key
)
632 else if (sector
> crq
->rb_key
)
642 static void cfq_activate_request(request_queue_t
*q
, struct request
*rq
)
644 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
646 cfqd
->rq_in_driver
++;
649 static void cfq_deactivate_request(request_queue_t
*q
, struct request
*rq
)
651 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
653 WARN_ON(!cfqd
->rq_in_driver
);
654 cfqd
->rq_in_driver
--;
657 static void cfq_remove_request(struct request
*rq
)
659 struct cfq_rq
*crq
= RQ_DATA(rq
);
661 list_del_init(&rq
->queuelist
);
663 cfq_del_crq_hash(crq
);
667 cfq_merge(request_queue_t
*q
, struct request
**req
, struct bio
*bio
)
669 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
670 struct request
*__rq
;
673 __rq
= cfq_find_rq_hash(cfqd
, bio
->bi_sector
);
674 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
675 ret
= ELEVATOR_BACK_MERGE
;
679 __rq
= cfq_find_rq_rb(cfqd
, bio
->bi_sector
+ bio_sectors(bio
));
680 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
681 ret
= ELEVATOR_FRONT_MERGE
;
685 return ELEVATOR_NO_MERGE
;
691 static void cfq_merged_request(request_queue_t
*q
, struct request
*req
)
693 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
694 struct cfq_rq
*crq
= RQ_DATA(req
);
696 cfq_del_crq_hash(crq
);
697 cfq_add_crq_hash(cfqd
, crq
);
699 if (rq_rb_key(req
) != crq
->rb_key
) {
700 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
702 cfq_update_next_crq(crq
);
703 cfq_reposition_crq_rb(cfqq
, crq
);
708 cfq_merged_requests(request_queue_t
*q
, struct request
*rq
,
709 struct request
*next
)
711 cfq_merged_request(q
, rq
);
714 * reposition in fifo if next is older than rq
716 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
717 time_before(next
->start_time
, rq
->start_time
))
718 list_move(&rq
->queuelist
, &next
->queuelist
);
720 cfq_remove_request(next
);
724 __cfq_set_active_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
728 * stop potential idle class queues waiting service
730 del_timer(&cfqd
->idle_class_timer
);
732 cfqq
->slice_start
= jiffies
;
734 cfqq
->slice_left
= 0;
735 cfq_clear_cfqq_must_alloc_slice(cfqq
);
736 cfq_clear_cfqq_fifo_expire(cfqq
);
739 cfqd
->active_queue
= cfqq
;
743 * current cfqq expired its slice (or was too idle), select new one
746 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
749 unsigned long now
= jiffies
;
751 if (cfq_cfqq_wait_request(cfqq
))
752 del_timer(&cfqd
->idle_slice_timer
);
754 if (!preempted
&& !cfq_cfqq_dispatched(cfqq
)) {
755 cfqq
->service_last
= now
;
756 cfq_schedule_dispatch(cfqd
);
759 cfq_clear_cfqq_must_dispatch(cfqq
);
760 cfq_clear_cfqq_wait_request(cfqq
);
763 * store what was left of this slice, if the queue idled out
766 if (time_after(cfqq
->slice_end
, now
))
767 cfqq
->slice_left
= cfqq
->slice_end
- now
;
769 cfqq
->slice_left
= 0;
771 if (cfq_cfqq_on_rr(cfqq
))
772 cfq_resort_rr_list(cfqq
, preempted
);
774 if (cfqq
== cfqd
->active_queue
)
775 cfqd
->active_queue
= NULL
;
777 if (cfqd
->active_cic
) {
778 put_io_context(cfqd
->active_cic
->ioc
);
779 cfqd
->active_cic
= NULL
;
782 cfqd
->dispatch_slice
= 0;
785 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, int preempted
)
787 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
790 __cfq_slice_expired(cfqd
, cfqq
, preempted
);
803 static int cfq_get_next_prio_level(struct cfq_data
*cfqd
)
812 for (p
= cfqd
->cur_prio
; p
<= cfqd
->cur_end_prio
; p
++) {
813 if (!list_empty(&cfqd
->rr_list
[p
])) {
822 if (++cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
823 cfqd
->cur_end_prio
= 0;
830 if (unlikely(prio
== -1))
833 BUG_ON(prio
>= CFQ_PRIO_LISTS
);
835 list_splice_init(&cfqd
->rr_list
[prio
], &cfqd
->cur_rr
);
837 cfqd
->cur_prio
= prio
+ 1;
838 if (cfqd
->cur_prio
> cfqd
->cur_end_prio
) {
839 cfqd
->cur_end_prio
= cfqd
->cur_prio
;
842 if (cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
844 cfqd
->cur_end_prio
= 0;
850 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
)
852 struct cfq_queue
*cfqq
= NULL
;
855 * if current list is non-empty, grab first entry. if it is empty,
856 * get next prio level and grab first entry then if any are spliced
858 if (!list_empty(&cfqd
->cur_rr
) || cfq_get_next_prio_level(cfqd
) != -1)
859 cfqq
= list_entry_cfqq(cfqd
->cur_rr
.next
);
862 * if we have idle queues and no rt or be queues had pending
863 * requests, either allow immediate service if the grace period
864 * has passed or arm the idle grace timer
866 if (!cfqq
&& !list_empty(&cfqd
->idle_rr
)) {
867 unsigned long end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
869 if (time_after_eq(jiffies
, end
))
870 cfqq
= list_entry_cfqq(cfqd
->idle_rr
.next
);
872 mod_timer(&cfqd
->idle_class_timer
, end
);
875 __cfq_set_active_queue(cfqd
, cfqq
);
879 static int cfq_arm_slice_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
884 WARN_ON(!RB_EMPTY(&cfqq
->sort_list
));
885 WARN_ON(cfqq
!= cfqd
->active_queue
);
888 * idle is disabled, either manually or by past process history
890 if (!cfqd
->cfq_slice_idle
)
892 if (!cfq_cfqq_idle_window(cfqq
))
895 * task has exited, don't wait
897 if (cfqd
->active_cic
&& !cfqd
->active_cic
->ioc
->task
)
900 cfq_mark_cfqq_must_dispatch(cfqq
);
901 cfq_mark_cfqq_wait_request(cfqq
);
903 sl
= min(cfqq
->slice_end
- 1, (unsigned long) cfqd
->cfq_slice_idle
);
904 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
908 static void cfq_dispatch_insert(request_queue_t
*q
, struct cfq_rq
*crq
)
910 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
911 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
913 cfqq
->next_crq
= cfq_find_next_crq(cfqd
, cfqq
, crq
);
914 cfq_remove_request(crq
->request
);
915 cfqq
->on_dispatch
[cfq_crq_is_sync(crq
)]++;
916 elv_dispatch_sort(q
, crq
->request
);
920 * return expired entry, or NULL to just start from scratch in rbtree
922 static inline struct cfq_rq
*cfq_check_fifo(struct cfq_queue
*cfqq
)
924 struct cfq_data
*cfqd
= cfqq
->cfqd
;
928 if (cfq_cfqq_fifo_expire(cfqq
))
931 if (!list_empty(&cfqq
->fifo
)) {
932 int fifo
= cfq_cfqq_class_sync(cfqq
);
934 crq
= RQ_DATA(list_entry_fifo(cfqq
->fifo
.next
));
936 if (time_after(jiffies
, rq
->start_time
+ cfqd
->cfq_fifo_expire
[fifo
])) {
937 cfq_mark_cfqq_fifo_expire(cfqq
);
946 * Scale schedule slice based on io priority. Use the sync time slice only
947 * if a queue is marked sync and has sync io queued. A sync queue with async
948 * io only, should not get full sync slice length.
951 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
953 const int base_slice
= cfqd
->cfq_slice
[cfq_cfqq_sync(cfqq
)];
955 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
957 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - cfqq
->ioprio
));
961 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
963 cfqq
->slice_end
= cfq_prio_to_slice(cfqd
, cfqq
) + jiffies
;
967 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
969 const int base_rq
= cfqd
->cfq_slice_async_rq
;
971 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
973 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
977 * get next queue for service
979 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
981 unsigned long now
= jiffies
;
982 struct cfq_queue
*cfqq
;
984 cfqq
= cfqd
->active_queue
;
991 if (!cfq_cfqq_must_dispatch(cfqq
) && time_after(now
, cfqq
->slice_end
))
995 * if queue has requests, dispatch one. if not, check if
996 * enough slice is left to wait for one
998 if (!RB_EMPTY(&cfqq
->sort_list
))
1000 else if (cfq_cfqq_class_sync(cfqq
) &&
1001 time_before(now
, cfqq
->slice_end
)) {
1002 if (cfq_arm_slice_timer(cfqd
, cfqq
))
1007 cfq_slice_expired(cfqd
, 0);
1009 cfqq
= cfq_set_active_queue(cfqd
);
1015 __cfq_dispatch_requests(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1020 BUG_ON(RB_EMPTY(&cfqq
->sort_list
));
1026 * follow expired path, else get first next available
1028 if ((crq
= cfq_check_fifo(cfqq
)) == NULL
)
1029 crq
= cfqq
->next_crq
;
1032 * finally, insert request into driver dispatch list
1034 cfq_dispatch_insert(cfqd
->queue
, crq
);
1036 cfqd
->dispatch_slice
++;
1039 if (!cfqd
->active_cic
) {
1040 atomic_inc(&crq
->io_context
->ioc
->refcount
);
1041 cfqd
->active_cic
= crq
->io_context
;
1044 if (RB_EMPTY(&cfqq
->sort_list
))
1047 } while (dispatched
< max_dispatch
);
1050 * if slice end isn't set yet, set it. if at least one request was
1051 * sync, use the sync time slice value
1053 if (!cfqq
->slice_end
)
1054 cfq_set_prio_slice(cfqd
, cfqq
);
1057 * expire an async queue immediately if it has used up its slice. idle
1058 * queue always expire after 1 dispatch round.
1060 if ((!cfq_cfqq_sync(cfqq
) &&
1061 cfqd
->dispatch_slice
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1062 cfq_class_idle(cfqq
))
1063 cfq_slice_expired(cfqd
, 0);
1069 cfq_forced_dispatch_cfqqs(struct list_head
*list
)
1072 struct cfq_queue
*cfqq
, *next
;
1075 list_for_each_entry_safe(cfqq
, next
, list
, cfq_list
) {
1076 while ((crq
= cfqq
->next_crq
)) {
1077 cfq_dispatch_insert(cfqq
->cfqd
->queue
, crq
);
1080 BUG_ON(!list_empty(&cfqq
->fifo
));
1086 cfq_forced_dispatch(struct cfq_data
*cfqd
)
1088 int i
, dispatched
= 0;
1090 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
1091 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->rr_list
[i
]);
1093 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->busy_rr
);
1094 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->cur_rr
);
1095 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->idle_rr
);
1097 cfq_slice_expired(cfqd
, 0);
1099 BUG_ON(cfqd
->busy_queues
);
1105 cfq_dispatch_requests(request_queue_t
*q
, int force
)
1107 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1108 struct cfq_queue
*cfqq
;
1110 if (!cfqd
->busy_queues
)
1113 if (unlikely(force
))
1114 return cfq_forced_dispatch(cfqd
);
1116 cfqq
= cfq_select_queue(cfqd
);
1121 * if idle window is disabled, allow queue buildup
1123 if (!cfq_cfqq_idle_window(cfqq
) &&
1124 cfqd
->rq_in_driver
>= cfqd
->cfq_max_depth
)
1127 cfq_clear_cfqq_must_dispatch(cfqq
);
1128 cfq_clear_cfqq_wait_request(cfqq
);
1129 del_timer(&cfqd
->idle_slice_timer
);
1131 max_dispatch
= cfqd
->cfq_quantum
;
1132 if (cfq_class_idle(cfqq
))
1135 return __cfq_dispatch_requests(cfqd
, cfqq
, max_dispatch
);
1142 * task holds one reference to the queue, dropped when task exits. each crq
1143 * in-flight on this queue also holds a reference, dropped when crq is freed.
1145 * queue lock must be held here.
1147 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1149 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1151 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1153 if (!atomic_dec_and_test(&cfqq
->ref
))
1156 BUG_ON(rb_first(&cfqq
->sort_list
));
1157 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1158 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1160 if (unlikely(cfqd
->active_queue
== cfqq
))
1161 __cfq_slice_expired(cfqd
, cfqq
, 0);
1163 cfq_put_cfqd(cfqq
->cfqd
);
1166 * it's on the empty list and still hashed
1168 list_del(&cfqq
->cfq_list
);
1169 hlist_del(&cfqq
->cfq_hash
);
1170 kmem_cache_free(cfq_pool
, cfqq
);
1173 static inline struct cfq_queue
*
1174 __cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned int prio
,
1177 struct hlist_head
*hash_list
= &cfqd
->cfq_hash
[hashval
];
1178 struct hlist_node
*entry
, *next
;
1180 hlist_for_each_safe(entry
, next
, hash_list
) {
1181 struct cfq_queue
*__cfqq
= list_entry_qhash(entry
);
1182 const unsigned short __p
= IOPRIO_PRIO_VALUE(__cfqq
->org_ioprio_class
, __cfqq
->org_ioprio
);
1184 if (__cfqq
->key
== key
&& (__p
== prio
|| prio
== CFQ_KEY_ANY
))
1191 static struct cfq_queue
*
1192 cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned short prio
)
1194 return __cfq_find_cfq_hash(cfqd
, key
, prio
, hash_long(key
, CFQ_QHASH_SHIFT
));
1197 static void cfq_free_io_context(struct cfq_io_context
*cic
)
1199 struct cfq_io_context
*__cic
;
1200 struct list_head
*entry
, *next
;
1202 list_for_each_safe(entry
, next
, &cic
->list
) {
1203 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1204 kmem_cache_free(cfq_ioc_pool
, __cic
);
1207 kmem_cache_free(cfq_ioc_pool
, cic
);
1211 * Called with interrupts disabled
1213 static void cfq_exit_single_io_context(struct cfq_io_context
*cic
)
1215 struct cfq_data
*cfqd
= cic
->key
;
1216 request_queue_t
*q
= cfqd
->queue
;
1218 WARN_ON(!irqs_disabled());
1220 spin_lock(q
->queue_lock
);
1222 if (unlikely(cic
->cfqq
== cfqd
->active_queue
))
1223 __cfq_slice_expired(cfqd
, cic
->cfqq
, 0);
1225 cfq_put_queue(cic
->cfqq
);
1228 spin_unlock(q
->queue_lock
);
1232 * Another task may update the task cic list, if it is doing a queue lookup
1233 * on its behalf. cfq_cic_lock excludes such concurrent updates
1235 static void cfq_exit_io_context(struct cfq_io_context
*cic
)
1237 struct cfq_io_context
*__cic
;
1238 struct list_head
*entry
;
1239 unsigned long flags
;
1241 local_irq_save(flags
);
1244 * put the reference this task is holding to the various queues
1246 list_for_each(entry
, &cic
->list
) {
1247 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1248 cfq_exit_single_io_context(__cic
);
1251 cfq_exit_single_io_context(cic
);
1252 local_irq_restore(flags
);
1255 static struct cfq_io_context
*
1256 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1258 struct cfq_io_context
*cic
= kmem_cache_alloc(cfq_ioc_pool
, gfp_mask
);
1261 INIT_LIST_HEAD(&cic
->list
);
1264 cic
->last_end_request
= jiffies
;
1265 cic
->ttime_total
= 0;
1266 cic
->ttime_samples
= 0;
1267 cic
->ttime_mean
= 0;
1268 cic
->dtor
= cfq_free_io_context
;
1269 cic
->exit
= cfq_exit_io_context
;
1275 static void cfq_init_prio_data(struct cfq_queue
*cfqq
)
1277 struct task_struct
*tsk
= current
;
1280 if (!cfq_cfqq_prio_changed(cfqq
))
1283 ioprio_class
= IOPRIO_PRIO_CLASS(tsk
->ioprio
);
1284 switch (ioprio_class
) {
1286 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1287 case IOPRIO_CLASS_NONE
:
1289 * no prio set, place us in the middle of the BE classes
1291 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1292 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1294 case IOPRIO_CLASS_RT
:
1295 cfqq
->ioprio
= task_ioprio(tsk
);
1296 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1298 case IOPRIO_CLASS_BE
:
1299 cfqq
->ioprio
= task_ioprio(tsk
);
1300 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1302 case IOPRIO_CLASS_IDLE
:
1303 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
1305 cfq_clear_cfqq_idle_window(cfqq
);
1310 * keep track of original prio settings in case we have to temporarily
1311 * elevate the priority of this queue
1313 cfqq
->org_ioprio
= cfqq
->ioprio
;
1314 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
1316 if (cfq_cfqq_on_rr(cfqq
))
1317 cfq_resort_rr_list(cfqq
, 0);
1319 cfq_clear_cfqq_prio_changed(cfqq
);
1322 static inline void changed_ioprio(struct cfq_io_context
*cic
)
1324 struct cfq_data
*cfqd
= cic
->key
;
1325 struct cfq_queue
*cfqq
;
1327 spin_lock(cfqd
->queue
->queue_lock
);
1330 cfq_mark_cfqq_prio_changed(cfqq
);
1331 cfq_init_prio_data(cfqq
);
1333 spin_unlock(cfqd
->queue
->queue_lock
);
1338 * callback from sys_ioprio_set, irqs are disabled
1340 static int cfq_ioc_set_ioprio(struct io_context
*ioc
, unsigned int ioprio
)
1342 struct cfq_io_context
*cic
= ioc
->cic
;
1344 changed_ioprio(cic
);
1346 list_for_each_entry(cic
, &cic
->list
, list
)
1347 changed_ioprio(cic
);
1352 static struct cfq_queue
*
1353 cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, unsigned short ioprio
,
1356 const int hashval
= hash_long(key
, CFQ_QHASH_SHIFT
);
1357 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1360 cfqq
= __cfq_find_cfq_hash(cfqd
, key
, ioprio
, hashval
);
1366 } else if (gfp_mask
& __GFP_WAIT
) {
1367 spin_unlock_irq(cfqd
->queue
->queue_lock
);
1368 new_cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1369 spin_lock_irq(cfqd
->queue
->queue_lock
);
1372 cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1377 memset(cfqq
, 0, sizeof(*cfqq
));
1379 INIT_HLIST_NODE(&cfqq
->cfq_hash
);
1380 INIT_LIST_HEAD(&cfqq
->cfq_list
);
1381 RB_CLEAR_ROOT(&cfqq
->sort_list
);
1382 INIT_LIST_HEAD(&cfqq
->fifo
);
1385 hlist_add_head(&cfqq
->cfq_hash
, &cfqd
->cfq_hash
[hashval
]);
1386 atomic_set(&cfqq
->ref
, 0);
1388 atomic_inc(&cfqd
->ref
);
1389 cfqq
->service_last
= 0;
1391 * set ->slice_left to allow preemption for a new process
1393 cfqq
->slice_left
= 2 * cfqd
->cfq_slice_idle
;
1394 cfq_mark_cfqq_idle_window(cfqq
);
1395 cfq_mark_cfqq_prio_changed(cfqq
);
1396 cfq_init_prio_data(cfqq
);
1400 kmem_cache_free(cfq_pool
, new_cfqq
);
1402 atomic_inc(&cfqq
->ref
);
1404 WARN_ON((gfp_mask
& __GFP_WAIT
) && !cfqq
);
1409 * Setup general io context and cfq io context. There can be several cfq
1410 * io contexts per general io context, if this process is doing io to more
1411 * than one device managed by cfq. Note that caller is holding a reference to
1412 * cfqq, so we don't need to worry about it disappearing
1414 static struct cfq_io_context
*
1415 cfq_get_io_context(struct cfq_data
*cfqd
, pid_t pid
, gfp_t gfp_mask
)
1417 struct io_context
*ioc
= NULL
;
1418 struct cfq_io_context
*cic
;
1420 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1422 ioc
= get_io_context(gfp_mask
);
1426 if ((cic
= ioc
->cic
) == NULL
) {
1427 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1433 * manually increment generic io_context usage count, it
1434 * cannot go away since we are already holding one ref to it
1438 ioc
->set_ioprio
= cfq_ioc_set_ioprio
;
1441 struct cfq_io_context
*__cic
;
1444 * the first cic on the list is actually the head itself
1446 if (cic
->key
== cfqd
)
1450 * cic exists, check if we already are there. linear search
1451 * should be ok here, the list will usually not be more than
1452 * 1 or a few entries long
1454 list_for_each_entry(__cic
, &cic
->list
, list
) {
1456 * this process is already holding a reference to
1457 * this queue, so no need to get one more
1459 if (__cic
->key
== cfqd
) {
1466 * nope, process doesn't have a cic assoicated with this
1467 * cfqq yet. get a new one and add to list
1469 __cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1475 list_add(&__cic
->list
, &cic
->list
);
1482 put_io_context(ioc
);
1487 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
1489 unsigned long elapsed
, ttime
;
1492 * if this context already has stuff queued, thinktime is from
1493 * last queue not last end
1496 if (time_after(cic
->last_end_request
, cic
->last_queue
))
1497 elapsed
= jiffies
- cic
->last_end_request
;
1499 elapsed
= jiffies
- cic
->last_queue
;
1501 elapsed
= jiffies
- cic
->last_end_request
;
1504 ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
1506 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
1507 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
1508 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
1511 #define sample_valid(samples) ((samples) > 80)
1514 * Disable idle window if the process thinks too long or seeks so much that
1518 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1519 struct cfq_io_context
*cic
)
1521 int enable_idle
= cfq_cfqq_idle_window(cfqq
);
1523 if (!cic
->ioc
->task
|| !cfqd
->cfq_slice_idle
)
1525 else if (sample_valid(cic
->ttime_samples
)) {
1526 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
1533 cfq_mark_cfqq_idle_window(cfqq
);
1535 cfq_clear_cfqq_idle_window(cfqq
);
1540 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1541 * no or if we aren't sure, a 1 will cause a preempt.
1544 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
1547 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1549 if (cfq_class_idle(new_cfqq
))
1555 if (cfq_class_idle(cfqq
))
1557 if (!cfq_cfqq_wait_request(new_cfqq
))
1560 * if it doesn't have slice left, forget it
1562 if (new_cfqq
->slice_left
< cfqd
->cfq_slice_idle
)
1564 if (cfq_crq_is_sync(crq
) && !cfq_cfqq_sync(cfqq
))
1571 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1572 * let it have half of its nominal slice.
1574 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1576 struct cfq_queue
*__cfqq
, *next
;
1578 list_for_each_entry_safe(__cfqq
, next
, &cfqd
->cur_rr
, cfq_list
)
1579 cfq_resort_rr_list(__cfqq
, 1);
1581 if (!cfqq
->slice_left
)
1582 cfqq
->slice_left
= cfq_prio_to_slice(cfqd
, cfqq
) / 2;
1584 cfqq
->slice_end
= cfqq
->slice_left
+ jiffies
;
1585 __cfq_slice_expired(cfqd
, cfqq
, 1);
1586 __cfq_set_active_queue(cfqd
, cfqq
);
1590 * should really be a ll_rw_blk.c helper
1592 static void cfq_start_queueing(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1594 request_queue_t
*q
= cfqd
->queue
;
1596 if (!blk_queue_plugged(q
))
1599 __generic_unplug_device(q
);
1603 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1604 * something we should do about it
1607 cfq_crq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1610 struct cfq_io_context
*cic
;
1612 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
1615 * we never wait for an async request and we don't allow preemption
1616 * of an async request. so just return early
1618 if (!cfq_crq_is_sync(crq
))
1621 cic
= crq
->io_context
;
1623 cfq_update_io_thinktime(cfqd
, cic
);
1624 cfq_update_idle_window(cfqd
, cfqq
, cic
);
1626 cic
->last_queue
= jiffies
;
1628 if (cfqq
== cfqd
->active_queue
) {
1630 * if we are waiting for a request for this queue, let it rip
1631 * immediately and flag that we must not expire this queue
1634 if (cfq_cfqq_wait_request(cfqq
)) {
1635 cfq_mark_cfqq_must_dispatch(cfqq
);
1636 del_timer(&cfqd
->idle_slice_timer
);
1637 cfq_start_queueing(cfqd
, cfqq
);
1639 } else if (cfq_should_preempt(cfqd
, cfqq
, crq
)) {
1641 * not the active queue - expire current slice if it is
1642 * idle and has expired it's mean thinktime or this new queue
1643 * has some old slice time left and is of higher priority
1645 cfq_preempt_queue(cfqd
, cfqq
);
1646 cfq_mark_cfqq_must_dispatch(cfqq
);
1647 cfq_start_queueing(cfqd
, cfqq
);
1651 static void cfq_insert_request(request_queue_t
*q
, struct request
*rq
)
1653 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1654 struct cfq_rq
*crq
= RQ_DATA(rq
);
1655 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1657 cfq_init_prio_data(cfqq
);
1659 cfq_add_crq_rb(crq
);
1661 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
1663 if (rq_mergeable(rq
))
1664 cfq_add_crq_hash(cfqd
, crq
);
1666 cfq_crq_enqueued(cfqd
, cfqq
, crq
);
1669 static void cfq_completed_request(request_queue_t
*q
, struct request
*rq
)
1671 struct cfq_rq
*crq
= RQ_DATA(rq
);
1672 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1673 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1674 const int sync
= cfq_crq_is_sync(crq
);
1679 WARN_ON(!cfqd
->rq_in_driver
);
1680 WARN_ON(!cfqq
->on_dispatch
[sync
]);
1681 cfqd
->rq_in_driver
--;
1682 cfqq
->on_dispatch
[sync
]--;
1684 if (!cfq_class_idle(cfqq
))
1685 cfqd
->last_end_request
= now
;
1687 if (!cfq_cfqq_dispatched(cfqq
)) {
1688 if (cfq_cfqq_on_rr(cfqq
)) {
1689 cfqq
->service_last
= now
;
1690 cfq_resort_rr_list(cfqq
, 0);
1692 cfq_schedule_dispatch(cfqd
);
1695 if (cfq_crq_is_sync(crq
))
1696 crq
->io_context
->last_end_request
= now
;
1699 static struct request
*
1700 cfq_former_request(request_queue_t
*q
, struct request
*rq
)
1702 struct cfq_rq
*crq
= RQ_DATA(rq
);
1703 struct rb_node
*rbprev
= rb_prev(&crq
->rb_node
);
1706 return rb_entry_crq(rbprev
)->request
;
1711 static struct request
*
1712 cfq_latter_request(request_queue_t
*q
, struct request
*rq
)
1714 struct cfq_rq
*crq
= RQ_DATA(rq
);
1715 struct rb_node
*rbnext
= rb_next(&crq
->rb_node
);
1718 return rb_entry_crq(rbnext
)->request
;
1724 * we temporarily boost lower priority queues if they are holding fs exclusive
1725 * resources. they are boosted to normal prio (CLASS_BE/4)
1727 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
1729 const int ioprio_class
= cfqq
->ioprio_class
;
1730 const int ioprio
= cfqq
->ioprio
;
1732 if (has_fs_excl()) {
1734 * boost idle prio on transactions that would lock out other
1735 * users of the filesystem
1737 if (cfq_class_idle(cfqq
))
1738 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1739 if (cfqq
->ioprio
> IOPRIO_NORM
)
1740 cfqq
->ioprio
= IOPRIO_NORM
;
1743 * check if we need to unboost the queue
1745 if (cfqq
->ioprio_class
!= cfqq
->org_ioprio_class
)
1746 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
1747 if (cfqq
->ioprio
!= cfqq
->org_ioprio
)
1748 cfqq
->ioprio
= cfqq
->org_ioprio
;
1752 * refile between round-robin lists if we moved the priority class
1754 if ((ioprio_class
!= cfqq
->ioprio_class
|| ioprio
!= cfqq
->ioprio
) &&
1755 cfq_cfqq_on_rr(cfqq
))
1756 cfq_resort_rr_list(cfqq
, 0);
1759 static inline pid_t
cfq_queue_pid(struct task_struct
*task
, int rw
)
1761 if (rw
== READ
|| process_sync(task
))
1764 return CFQ_KEY_ASYNC
;
1768 __cfq_may_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1769 struct task_struct
*task
, int rw
)
1772 if ((cfq_cfqq_wait_request(cfqq
) || cfq_cfqq_must_alloc(cfqq
)) &&
1773 !cfq_cfqq_must_alloc_slice(cfqq
)) {
1774 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1775 return ELV_MQUEUE_MUST
;
1778 return ELV_MQUEUE_MAY
;
1780 if (!cfqq
|| task
->flags
& PF_MEMALLOC
)
1781 return ELV_MQUEUE_MAY
;
1782 if (!cfqq
->allocated
[rw
] || cfq_cfqq_must_alloc(cfqq
)) {
1783 if (cfq_cfqq_wait_request(cfqq
))
1784 return ELV_MQUEUE_MUST
;
1787 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1788 * can quickly flood the queue with writes from a single task
1790 if (rw
== READ
|| !cfq_cfqq_must_alloc_slice(cfqq
)) {
1791 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1792 return ELV_MQUEUE_MUST
;
1795 return ELV_MQUEUE_MAY
;
1797 if (cfq_class_idle(cfqq
))
1798 return ELV_MQUEUE_NO
;
1799 if (cfqq
->allocated
[rw
] >= cfqd
->max_queued
) {
1800 struct io_context
*ioc
= get_io_context(GFP_ATOMIC
);
1801 int ret
= ELV_MQUEUE_NO
;
1803 if (ioc
&& ioc
->nr_batch_requests
)
1804 ret
= ELV_MQUEUE_MAY
;
1806 put_io_context(ioc
);
1810 return ELV_MQUEUE_MAY
;
1814 static int cfq_may_queue(request_queue_t
*q
, int rw
, struct bio
*bio
)
1816 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1817 struct task_struct
*tsk
= current
;
1818 struct cfq_queue
*cfqq
;
1821 * don't force setup of a queue from here, as a call to may_queue
1822 * does not necessarily imply that a request actually will be queued.
1823 * so just lookup a possibly existing queue, or return 'may queue'
1826 cfqq
= cfq_find_cfq_hash(cfqd
, cfq_queue_pid(tsk
, rw
), tsk
->ioprio
);
1828 cfq_init_prio_data(cfqq
);
1829 cfq_prio_boost(cfqq
);
1831 return __cfq_may_queue(cfqd
, cfqq
, tsk
, rw
);
1834 return ELV_MQUEUE_MAY
;
1837 static void cfq_check_waiters(request_queue_t
*q
, struct cfq_queue
*cfqq
)
1839 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1840 struct request_list
*rl
= &q
->rq
;
1842 if (cfqq
->allocated
[READ
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
1844 if (waitqueue_active(&rl
->wait
[READ
]))
1845 wake_up(&rl
->wait
[READ
]);
1848 if (cfqq
->allocated
[WRITE
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
1850 if (waitqueue_active(&rl
->wait
[WRITE
]))
1851 wake_up(&rl
->wait
[WRITE
]);
1856 * queue lock held here
1858 static void cfq_put_request(request_queue_t
*q
, struct request
*rq
)
1860 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1861 struct cfq_rq
*crq
= RQ_DATA(rq
);
1864 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1865 const int rw
= rq_data_dir(rq
);
1867 BUG_ON(!cfqq
->allocated
[rw
]);
1868 cfqq
->allocated
[rw
]--;
1870 put_io_context(crq
->io_context
->ioc
);
1872 mempool_free(crq
, cfqd
->crq_pool
);
1873 rq
->elevator_private
= NULL
;
1875 cfq_check_waiters(q
, cfqq
);
1876 cfq_put_queue(cfqq
);
1881 * Allocate cfq data structures associated with this request.
1884 cfq_set_request(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
,
1887 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1888 struct task_struct
*tsk
= current
;
1889 struct cfq_io_context
*cic
;
1890 const int rw
= rq_data_dir(rq
);
1891 pid_t key
= cfq_queue_pid(tsk
, rw
);
1892 struct cfq_queue
*cfqq
;
1894 unsigned long flags
;
1896 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1898 cic
= cfq_get_io_context(cfqd
, key
, gfp_mask
);
1900 spin_lock_irqsave(q
->queue_lock
, flags
);
1906 cfqq
= cfq_get_queue(cfqd
, key
, tsk
->ioprio
, gfp_mask
);
1914 cfqq
->allocated
[rw
]++;
1915 cfq_clear_cfqq_must_alloc(cfqq
);
1916 cfqd
->rq_starved
= 0;
1917 atomic_inc(&cfqq
->ref
);
1918 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1920 crq
= mempool_alloc(cfqd
->crq_pool
, gfp_mask
);
1922 RB_CLEAR(&crq
->rb_node
);
1925 INIT_HLIST_NODE(&crq
->hash
);
1926 crq
->cfq_queue
= cfqq
;
1927 crq
->io_context
= cic
;
1929 if (rw
== READ
|| process_sync(tsk
))
1930 cfq_mark_crq_is_sync(crq
);
1932 cfq_clear_crq_is_sync(crq
);
1934 rq
->elevator_private
= crq
;
1938 spin_lock_irqsave(q
->queue_lock
, flags
);
1939 cfqq
->allocated
[rw
]--;
1940 if (!(cfqq
->allocated
[0] + cfqq
->allocated
[1]))
1941 cfq_mark_cfqq_must_alloc(cfqq
);
1942 cfq_put_queue(cfqq
);
1945 put_io_context(cic
->ioc
);
1947 * mark us rq allocation starved. we need to kickstart the process
1948 * ourselves if there are no pending requests that can do it for us.
1949 * that would be an extremely rare OOM situation
1951 cfqd
->rq_starved
= 1;
1952 cfq_schedule_dispatch(cfqd
);
1953 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1957 static void cfq_kick_queue(void *data
)
1959 request_queue_t
*q
= data
;
1960 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1961 unsigned long flags
;
1963 spin_lock_irqsave(q
->queue_lock
, flags
);
1965 if (cfqd
->rq_starved
) {
1966 struct request_list
*rl
= &q
->rq
;
1969 * we aren't guaranteed to get a request after this, but we
1970 * have to be opportunistic
1973 if (waitqueue_active(&rl
->wait
[READ
]))
1974 wake_up(&rl
->wait
[READ
]);
1975 if (waitqueue_active(&rl
->wait
[WRITE
]))
1976 wake_up(&rl
->wait
[WRITE
]);
1981 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1985 * Timer running if the active_queue is currently idling inside its time slice
1987 static void cfq_idle_slice_timer(unsigned long data
)
1989 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
1990 struct cfq_queue
*cfqq
;
1991 unsigned long flags
;
1993 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1995 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
1996 unsigned long now
= jiffies
;
2001 if (time_after(now
, cfqq
->slice_end
))
2005 * only expire and reinvoke request handler, if there are
2006 * other queues with pending requests
2008 if (!cfqd
->busy_queues
) {
2009 cfqd
->idle_slice_timer
.expires
= min(now
+ cfqd
->cfq_slice_idle
, cfqq
->slice_end
);
2010 add_timer(&cfqd
->idle_slice_timer
);
2015 * not expired and it has a request pending, let it dispatch
2017 if (!RB_EMPTY(&cfqq
->sort_list
)) {
2018 cfq_mark_cfqq_must_dispatch(cfqq
);
2023 cfq_slice_expired(cfqd
, 0);
2025 cfq_schedule_dispatch(cfqd
);
2027 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2031 * Timer running if an idle class queue is waiting for service
2033 static void cfq_idle_class_timer(unsigned long data
)
2035 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2036 unsigned long flags
, end
;
2038 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2041 * race with a non-idle queue, reset timer
2043 end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
2044 if (!time_after_eq(jiffies
, end
)) {
2045 cfqd
->idle_class_timer
.expires
= end
;
2046 add_timer(&cfqd
->idle_class_timer
);
2048 cfq_schedule_dispatch(cfqd
);
2050 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2053 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2055 del_timer_sync(&cfqd
->idle_slice_timer
);
2056 del_timer_sync(&cfqd
->idle_class_timer
);
2057 blk_sync_queue(cfqd
->queue
);
2060 static void cfq_put_cfqd(struct cfq_data
*cfqd
)
2062 request_queue_t
*q
= cfqd
->queue
;
2064 if (!atomic_dec_and_test(&cfqd
->ref
))
2067 cfq_shutdown_timer_wq(cfqd
);
2070 mempool_destroy(cfqd
->crq_pool
);
2071 kfree(cfqd
->crq_hash
);
2072 kfree(cfqd
->cfq_hash
);
2076 static void cfq_exit_queue(elevator_t
*e
)
2078 struct cfq_data
*cfqd
= e
->elevator_data
;
2080 cfq_shutdown_timer_wq(cfqd
);
2084 static int cfq_init_queue(request_queue_t
*q
, elevator_t
*e
)
2086 struct cfq_data
*cfqd
;
2089 cfqd
= kmalloc(sizeof(*cfqd
), GFP_KERNEL
);
2093 memset(cfqd
, 0, sizeof(*cfqd
));
2095 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2096 INIT_LIST_HEAD(&cfqd
->rr_list
[i
]);
2098 INIT_LIST_HEAD(&cfqd
->busy_rr
);
2099 INIT_LIST_HEAD(&cfqd
->cur_rr
);
2100 INIT_LIST_HEAD(&cfqd
->idle_rr
);
2101 INIT_LIST_HEAD(&cfqd
->empty_list
);
2103 cfqd
->crq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_MHASH_ENTRIES
, GFP_KERNEL
);
2104 if (!cfqd
->crq_hash
)
2107 cfqd
->cfq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_QHASH_ENTRIES
, GFP_KERNEL
);
2108 if (!cfqd
->cfq_hash
)
2111 cfqd
->crq_pool
= mempool_create(BLKDEV_MIN_RQ
, mempool_alloc_slab
, mempool_free_slab
, crq_pool
);
2112 if (!cfqd
->crq_pool
)
2115 for (i
= 0; i
< CFQ_MHASH_ENTRIES
; i
++)
2116 INIT_HLIST_HEAD(&cfqd
->crq_hash
[i
]);
2117 for (i
= 0; i
< CFQ_QHASH_ENTRIES
; i
++)
2118 INIT_HLIST_HEAD(&cfqd
->cfq_hash
[i
]);
2120 e
->elevator_data
= cfqd
;
2123 atomic_inc(&q
->refcnt
);
2125 cfqd
->max_queued
= q
->nr_requests
/ 4;
2126 q
->nr_batching
= cfq_queued
;
2128 init_timer(&cfqd
->idle_slice_timer
);
2129 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
2130 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
2132 init_timer(&cfqd
->idle_class_timer
);
2133 cfqd
->idle_class_timer
.function
= cfq_idle_class_timer
;
2134 cfqd
->idle_class_timer
.data
= (unsigned long) cfqd
;
2136 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
, q
);
2138 atomic_set(&cfqd
->ref
, 1);
2140 cfqd
->cfq_queued
= cfq_queued
;
2141 cfqd
->cfq_quantum
= cfq_quantum
;
2142 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
2143 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
2144 cfqd
->cfq_back_max
= cfq_back_max
;
2145 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
2146 cfqd
->cfq_slice
[0] = cfq_slice_async
;
2147 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
2148 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
2149 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
2150 cfqd
->cfq_max_depth
= cfq_max_depth
;
2154 kfree(cfqd
->cfq_hash
);
2156 kfree(cfqd
->crq_hash
);
2162 static void cfq_slab_kill(void)
2165 kmem_cache_destroy(crq_pool
);
2167 kmem_cache_destroy(cfq_pool
);
2169 kmem_cache_destroy(cfq_ioc_pool
);
2172 static int __init
cfq_slab_setup(void)
2174 crq_pool
= kmem_cache_create("crq_pool", sizeof(struct cfq_rq
), 0, 0,
2179 cfq_pool
= kmem_cache_create("cfq_pool", sizeof(struct cfq_queue
), 0, 0,
2184 cfq_ioc_pool
= kmem_cache_create("cfq_ioc_pool",
2185 sizeof(struct cfq_io_context
), 0, 0, NULL
, NULL
);
2196 * sysfs parts below -->
2198 struct cfq_fs_entry
{
2199 struct attribute attr
;
2200 ssize_t (*show
)(struct cfq_data
*, char *);
2201 ssize_t (*store
)(struct cfq_data
*, const char *, size_t);
2205 cfq_var_show(unsigned int var
, char *page
)
2207 return sprintf(page
, "%d\n", var
);
2211 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
2213 char *p
= (char *) page
;
2215 *var
= simple_strtoul(p
, &p
, 10);
2219 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2220 static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2222 unsigned int __data = __VAR; \
2224 __data = jiffies_to_msecs(__data); \
2225 return cfq_var_show(__data, (page)); \
2227 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
2228 SHOW_FUNCTION(cfq_queued_show
, cfqd
->cfq_queued
, 0);
2229 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
2230 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
2231 SHOW_FUNCTION(cfq_back_max_show
, cfqd
->cfq_back_max
, 0);
2232 SHOW_FUNCTION(cfq_back_penalty_show
, cfqd
->cfq_back_penalty
, 0);
2233 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
2234 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
2235 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
2236 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
2237 SHOW_FUNCTION(cfq_max_depth_show
, cfqd
->cfq_max_depth
, 0);
2238 #undef SHOW_FUNCTION
2240 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2241 static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2243 unsigned int __data; \
2244 int ret = cfq_var_store(&__data, (page), count); \
2245 if (__data < (MIN)) \
2247 else if (__data > (MAX)) \
2250 *(__PTR) = msecs_to_jiffies(__data); \
2252 *(__PTR) = __data; \
2255 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
2256 STORE_FUNCTION(cfq_queued_store
, &cfqd
->cfq_queued
, 1, UINT_MAX
, 0);
2257 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1, UINT_MAX
, 1);
2258 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1, UINT_MAX
, 1);
2259 STORE_FUNCTION(cfq_back_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
2260 STORE_FUNCTION(cfq_back_penalty_store
, &cfqd
->cfq_back_penalty
, 1, UINT_MAX
, 0);
2261 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
2262 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
2263 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
2264 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1, UINT_MAX
, 0);
2265 STORE_FUNCTION(cfq_max_depth_store
, &cfqd
->cfq_max_depth
, 1, UINT_MAX
, 0);
2266 #undef STORE_FUNCTION
2268 static struct cfq_fs_entry cfq_quantum_entry
= {
2269 .attr
= {.name
= "quantum", .mode
= S_IRUGO
| S_IWUSR
},
2270 .show
= cfq_quantum_show
,
2271 .store
= cfq_quantum_store
,
2273 static struct cfq_fs_entry cfq_queued_entry
= {
2274 .attr
= {.name
= "queued", .mode
= S_IRUGO
| S_IWUSR
},
2275 .show
= cfq_queued_show
,
2276 .store
= cfq_queued_store
,
2278 static struct cfq_fs_entry cfq_fifo_expire_sync_entry
= {
2279 .attr
= {.name
= "fifo_expire_sync", .mode
= S_IRUGO
| S_IWUSR
},
2280 .show
= cfq_fifo_expire_sync_show
,
2281 .store
= cfq_fifo_expire_sync_store
,
2283 static struct cfq_fs_entry cfq_fifo_expire_async_entry
= {
2284 .attr
= {.name
= "fifo_expire_async", .mode
= S_IRUGO
| S_IWUSR
},
2285 .show
= cfq_fifo_expire_async_show
,
2286 .store
= cfq_fifo_expire_async_store
,
2288 static struct cfq_fs_entry cfq_back_max_entry
= {
2289 .attr
= {.name
= "back_seek_max", .mode
= S_IRUGO
| S_IWUSR
},
2290 .show
= cfq_back_max_show
,
2291 .store
= cfq_back_max_store
,
2293 static struct cfq_fs_entry cfq_back_penalty_entry
= {
2294 .attr
= {.name
= "back_seek_penalty", .mode
= S_IRUGO
| S_IWUSR
},
2295 .show
= cfq_back_penalty_show
,
2296 .store
= cfq_back_penalty_store
,
2298 static struct cfq_fs_entry cfq_slice_sync_entry
= {
2299 .attr
= {.name
= "slice_sync", .mode
= S_IRUGO
| S_IWUSR
},
2300 .show
= cfq_slice_sync_show
,
2301 .store
= cfq_slice_sync_store
,
2303 static struct cfq_fs_entry cfq_slice_async_entry
= {
2304 .attr
= {.name
= "slice_async", .mode
= S_IRUGO
| S_IWUSR
},
2305 .show
= cfq_slice_async_show
,
2306 .store
= cfq_slice_async_store
,
2308 static struct cfq_fs_entry cfq_slice_async_rq_entry
= {
2309 .attr
= {.name
= "slice_async_rq", .mode
= S_IRUGO
| S_IWUSR
},
2310 .show
= cfq_slice_async_rq_show
,
2311 .store
= cfq_slice_async_rq_store
,
2313 static struct cfq_fs_entry cfq_slice_idle_entry
= {
2314 .attr
= {.name
= "slice_idle", .mode
= S_IRUGO
| S_IWUSR
},
2315 .show
= cfq_slice_idle_show
,
2316 .store
= cfq_slice_idle_store
,
2318 static struct cfq_fs_entry cfq_max_depth_entry
= {
2319 .attr
= {.name
= "max_depth", .mode
= S_IRUGO
| S_IWUSR
},
2320 .show
= cfq_max_depth_show
,
2321 .store
= cfq_max_depth_store
,
2324 static struct attribute
*default_attrs
[] = {
2325 &cfq_quantum_entry
.attr
,
2326 &cfq_queued_entry
.attr
,
2327 &cfq_fifo_expire_sync_entry
.attr
,
2328 &cfq_fifo_expire_async_entry
.attr
,
2329 &cfq_back_max_entry
.attr
,
2330 &cfq_back_penalty_entry
.attr
,
2331 &cfq_slice_sync_entry
.attr
,
2332 &cfq_slice_async_entry
.attr
,
2333 &cfq_slice_async_rq_entry
.attr
,
2334 &cfq_slice_idle_entry
.attr
,
2335 &cfq_max_depth_entry
.attr
,
2339 #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2342 cfq_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
2344 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2345 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2350 return entry
->show(e
->elevator_data
, page
);
2354 cfq_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
2355 const char *page
, size_t length
)
2357 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2358 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2363 return entry
->store(e
->elevator_data
, page
, length
);
2366 static struct sysfs_ops cfq_sysfs_ops
= {
2367 .show
= cfq_attr_show
,
2368 .store
= cfq_attr_store
,
2371 static struct kobj_type cfq_ktype
= {
2372 .sysfs_ops
= &cfq_sysfs_ops
,
2373 .default_attrs
= default_attrs
,
2376 static struct elevator_type iosched_cfq
= {
2378 .elevator_merge_fn
= cfq_merge
,
2379 .elevator_merged_fn
= cfq_merged_request
,
2380 .elevator_merge_req_fn
= cfq_merged_requests
,
2381 .elevator_dispatch_fn
= cfq_dispatch_requests
,
2382 .elevator_add_req_fn
= cfq_insert_request
,
2383 .elevator_activate_req_fn
= cfq_activate_request
,
2384 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
2385 .elevator_queue_empty_fn
= cfq_queue_empty
,
2386 .elevator_completed_req_fn
= cfq_completed_request
,
2387 .elevator_former_req_fn
= cfq_former_request
,
2388 .elevator_latter_req_fn
= cfq_latter_request
,
2389 .elevator_set_req_fn
= cfq_set_request
,
2390 .elevator_put_req_fn
= cfq_put_request
,
2391 .elevator_may_queue_fn
= cfq_may_queue
,
2392 .elevator_init_fn
= cfq_init_queue
,
2393 .elevator_exit_fn
= cfq_exit_queue
,
2395 .elevator_ktype
= &cfq_ktype
,
2396 .elevator_name
= "cfq",
2397 .elevator_owner
= THIS_MODULE
,
2400 static int __init
cfq_init(void)
2405 * could be 0 on HZ < 1000 setups
2407 if (!cfq_slice_async
)
2408 cfq_slice_async
= 1;
2409 if (!cfq_slice_idle
)
2412 if (cfq_slab_setup())
2415 ret
= elv_register(&iosched_cfq
);
2422 static void __exit
cfq_exit(void)
2424 elv_unregister(&iosched_cfq
);
2428 module_init(cfq_init
);
2429 module_exit(cfq_exit
);
2431 MODULE_AUTHOR("Jens Axboe");
2432 MODULE_LICENSE("GPL");
2433 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");