2 * linux/drivers/block/cfq-iosched.c
4 * CFQ, or complete fairness queueing, disk scheduler.
6 * Based on ideas from a previously unfinished io
7 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
9 * Copyright (C) 2003 Jens Axboe <axboe@suse.de>
11 #include <linux/kernel.h>
13 #include <linux/blkdev.h>
14 #include <linux/elevator.h>
15 #include <linux/bio.h>
16 #include <linux/config.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/init.h>
20 #include <linux/compiler.h>
21 #include <linux/hash.h>
22 #include <linux/rbtree.h>
23 #include <linux/mempool.h>
24 #include <linux/ioprio.h>
25 #include <linux/writeback.h>
30 static int cfq_quantum
= 4; /* max queue in one round of service */
31 static int cfq_queued
= 8; /* minimum rq allocate limit per-queue*/
32 static int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
33 static int cfq_back_max
= 16 * 1024; /* maximum backwards seek, in KiB */
34 static int cfq_back_penalty
= 2; /* penalty of a backwards seek */
36 static int cfq_slice_sync
= HZ
/ 10;
37 static int cfq_slice_async
= HZ
/ 25;
38 static int cfq_slice_async_rq
= 2;
39 static int cfq_slice_idle
= HZ
/ 100;
41 #define CFQ_IDLE_GRACE (HZ / 10)
42 #define CFQ_SLICE_SCALE (5)
44 #define CFQ_KEY_ASYNC (0)
45 #define CFQ_KEY_ANY (0xffff)
48 * disable queueing at the driver/hardware level
50 static int cfq_max_depth
= 2;
53 * for the hash of cfqq inside the cfqd
55 #define CFQ_QHASH_SHIFT 6
56 #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
57 #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
60 * for the hash of crq inside the cfqq
62 #define CFQ_MHASH_SHIFT 6
63 #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
64 #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
65 #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
66 #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
67 #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
69 #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
70 #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
72 #define RQ_DATA(rq) (rq)->elevator_private
78 #define RB_EMPTY(node) ((node)->rb_node == NULL)
79 #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
80 #define RB_CLEAR(node) do { \
81 (node)->rb_parent = NULL; \
82 RB_CLEAR_COLOR((node)); \
83 (node)->rb_right = NULL; \
84 (node)->rb_left = NULL; \
86 #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
87 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
88 #define rq_rb_key(rq) (rq)->sector
90 static kmem_cache_t
*crq_pool
;
91 static kmem_cache_t
*cfq_pool
;
92 static kmem_cache_t
*cfq_ioc_pool
;
94 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
95 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
96 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
97 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
102 #define cfq_cfqq_dispatched(cfqq) \
103 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
105 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
107 #define cfq_cfqq_sync(cfqq) \
108 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
111 * Per block device queue structure
115 request_queue_t
*queue
;
118 * rr list of queues with requests and the count of them
120 struct list_head rr_list
[CFQ_PRIO_LISTS
];
121 struct list_head busy_rr
;
122 struct list_head cur_rr
;
123 struct list_head idle_rr
;
124 unsigned int busy_queues
;
127 * non-ordered list of empty cfqq's
129 struct list_head empty_list
;
134 struct hlist_head
*cfq_hash
;
137 * global crq hash for all queues
139 struct hlist_head
*crq_hash
;
141 unsigned int max_queued
;
148 * schedule slice state info
151 * idle window management
153 struct timer_list idle_slice_timer
;
154 struct work_struct unplug_work
;
156 struct cfq_queue
*active_queue
;
157 struct cfq_io_context
*active_cic
;
158 int cur_prio
, cur_end_prio
;
159 unsigned int dispatch_slice
;
161 struct timer_list idle_class_timer
;
163 sector_t last_sector
;
164 unsigned long last_end_request
;
166 unsigned int rq_starved
;
169 * tunables, see top of file
171 unsigned int cfq_quantum
;
172 unsigned int cfq_queued
;
173 unsigned int cfq_fifo_expire
[2];
174 unsigned int cfq_back_penalty
;
175 unsigned int cfq_back_max
;
176 unsigned int cfq_slice
[2];
177 unsigned int cfq_slice_async_rq
;
178 unsigned int cfq_slice_idle
;
179 unsigned int cfq_max_depth
;
183 * Per process-grouping structure
186 /* reference count */
188 /* parent cfq_data */
189 struct cfq_data
*cfqd
;
190 /* cfqq lookup hash */
191 struct hlist_node cfq_hash
;
194 /* on either rr or empty list of cfqd */
195 struct list_head cfq_list
;
196 /* sorted list of pending requests */
197 struct rb_root sort_list
;
198 /* if fifo isn't expired, next request to serve */
199 struct cfq_rq
*next_crq
;
200 /* requests queued in sort_list */
202 /* currently allocated requests */
204 /* fifo list of requests in sort_list */
205 struct list_head fifo
;
207 unsigned long slice_start
;
208 unsigned long slice_end
;
209 unsigned long slice_left
;
210 unsigned long service_last
;
212 /* number of requests that are on the dispatch list */
215 /* io prio of this group */
216 unsigned short ioprio
, org_ioprio
;
217 unsigned short ioprio_class
, org_ioprio_class
;
219 /* various state flags, see below */
224 struct rb_node rb_node
;
226 struct request
*request
;
227 struct hlist_node hash
;
229 struct cfq_queue
*cfq_queue
;
230 struct cfq_io_context
*io_context
;
232 unsigned int crq_flags
;
235 enum cfqq_state_flags
{
236 CFQ_CFQQ_FLAG_on_rr
= 0,
237 CFQ_CFQQ_FLAG_wait_request
,
238 CFQ_CFQQ_FLAG_must_alloc
,
239 CFQ_CFQQ_FLAG_must_alloc_slice
,
240 CFQ_CFQQ_FLAG_must_dispatch
,
241 CFQ_CFQQ_FLAG_fifo_expire
,
242 CFQ_CFQQ_FLAG_idle_window
,
243 CFQ_CFQQ_FLAG_prio_changed
,
244 CFQ_CFQQ_FLAG_expired
,
247 #define CFQ_CFQQ_FNS(name) \
248 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
250 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
252 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
254 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
256 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
258 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
262 CFQ_CFQQ_FNS(wait_request
);
263 CFQ_CFQQ_FNS(must_alloc
);
264 CFQ_CFQQ_FNS(must_alloc_slice
);
265 CFQ_CFQQ_FNS(must_dispatch
);
266 CFQ_CFQQ_FNS(fifo_expire
);
267 CFQ_CFQQ_FNS(idle_window
);
268 CFQ_CFQQ_FNS(prio_changed
);
269 CFQ_CFQQ_FNS(expired
);
272 enum cfq_rq_state_flags
{
273 CFQ_CRQ_FLAG_is_sync
= 0,
276 #define CFQ_CRQ_FNS(name) \
277 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
279 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
281 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
283 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
285 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
287 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
290 CFQ_CRQ_FNS(is_sync
);
293 static struct cfq_queue
*cfq_find_cfq_hash(struct cfq_data
*, unsigned int, unsigned short);
294 static void cfq_dispatch_insert(request_queue_t
*, struct cfq_rq
*);
295 static void cfq_put_cfqd(struct cfq_data
*cfqd
);
297 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
300 * lots of deadline iosched dupes, can be abstracted later...
302 static inline void cfq_del_crq_hash(struct cfq_rq
*crq
)
304 hlist_del_init(&crq
->hash
);
307 static inline void cfq_add_crq_hash(struct cfq_data
*cfqd
, struct cfq_rq
*crq
)
309 const int hash_idx
= CFQ_MHASH_FN(rq_hash_key(crq
->request
));
311 hlist_add_head(&crq
->hash
, &cfqd
->crq_hash
[hash_idx
]);
314 static struct request
*cfq_find_rq_hash(struct cfq_data
*cfqd
, sector_t offset
)
316 struct hlist_head
*hash_list
= &cfqd
->crq_hash
[CFQ_MHASH_FN(offset
)];
317 struct hlist_node
*entry
, *next
;
319 hlist_for_each_safe(entry
, next
, hash_list
) {
320 struct cfq_rq
*crq
= list_entry_hash(entry
);
321 struct request
*__rq
= crq
->request
;
323 if (!rq_mergeable(__rq
)) {
324 cfq_del_crq_hash(crq
);
328 if (rq_hash_key(__rq
) == offset
)
336 * scheduler run of queue, if there are requests pending and no one in the
337 * driver that will restart queueing
339 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
341 if (!cfqd
->rq_in_driver
&& cfqd
->busy_queues
)
342 kblockd_schedule_work(&cfqd
->unplug_work
);
345 static int cfq_queue_empty(request_queue_t
*q
)
347 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
349 return !cfqd
->busy_queues
;
353 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
354 * We choose the request that is closest to the head right now. Distance
355 * behind the head are penalized and only allowed to a certain extent.
357 static struct cfq_rq
*
358 cfq_choose_req(struct cfq_data
*cfqd
, struct cfq_rq
*crq1
, struct cfq_rq
*crq2
)
360 sector_t last
, s1
, s2
, d1
= 0, d2
= 0;
361 int r1_wrap
= 0, r2_wrap
= 0; /* requests are behind the disk head */
362 unsigned long back_max
;
364 if (crq1
== NULL
|| crq1
== crq2
)
369 if (cfq_crq_is_sync(crq1
) && !cfq_crq_is_sync(crq2
))
371 else if (cfq_crq_is_sync(crq2
) && !cfq_crq_is_sync(crq1
))
374 s1
= crq1
->request
->sector
;
375 s2
= crq2
->request
->sector
;
377 last
= cfqd
->last_sector
;
380 * by definition, 1KiB is 2 sectors
382 back_max
= cfqd
->cfq_back_max
* 2;
385 * Strict one way elevator _except_ in the case where we allow
386 * short backward seeks which are biased as twice the cost of a
387 * similar forward seek.
391 else if (s1
+ back_max
>= last
)
392 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
398 else if (s2
+ back_max
>= last
)
399 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
403 /* Found required data */
404 if (!r1_wrap
&& r2_wrap
)
406 else if (!r2_wrap
&& r1_wrap
)
408 else if (r1_wrap
&& r2_wrap
) {
409 /* both behind the head */
416 /* Both requests in front of the head */
430 * would be nice to take fifo expire time into account as well
432 static struct cfq_rq
*
433 cfq_find_next_crq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
436 struct cfq_rq
*crq_next
= NULL
, *crq_prev
= NULL
;
437 struct rb_node
*rbnext
, *rbprev
;
439 if (!(rbnext
= rb_next(&last
->rb_node
))) {
440 rbnext
= rb_first(&cfqq
->sort_list
);
441 if (rbnext
== &last
->rb_node
)
445 rbprev
= rb_prev(&last
->rb_node
);
448 crq_prev
= rb_entry_crq(rbprev
);
450 crq_next
= rb_entry_crq(rbnext
);
452 return cfq_choose_req(cfqd
, crq_next
, crq_prev
);
455 static void cfq_update_next_crq(struct cfq_rq
*crq
)
457 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
459 if (cfqq
->next_crq
== crq
)
460 cfqq
->next_crq
= cfq_find_next_crq(cfqq
->cfqd
, cfqq
, crq
);
463 static void cfq_resort_rr_list(struct cfq_queue
*cfqq
, int preempted
)
465 struct cfq_data
*cfqd
= cfqq
->cfqd
;
466 struct list_head
*list
, *entry
;
468 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
470 list_del(&cfqq
->cfq_list
);
472 if (cfq_class_rt(cfqq
))
473 list
= &cfqd
->cur_rr
;
474 else if (cfq_class_idle(cfqq
))
475 list
= &cfqd
->idle_rr
;
478 * if cfqq has requests in flight, don't allow it to be
479 * found in cfq_set_active_queue before it has finished them.
480 * this is done to increase fairness between a process that
481 * has lots of io pending vs one that only generates one
482 * sporadically or synchronously
484 if (cfq_cfqq_dispatched(cfqq
))
485 list
= &cfqd
->busy_rr
;
487 list
= &cfqd
->rr_list
[cfqq
->ioprio
];
491 * if queue was preempted, just add to front to be fair. busy_rr
494 if (preempted
|| list
== &cfqd
->busy_rr
) {
495 list_add(&cfqq
->cfq_list
, list
);
500 * sort by when queue was last serviced
503 while ((entry
= entry
->prev
) != list
) {
504 struct cfq_queue
*__cfqq
= list_entry_cfqq(entry
);
506 if (!__cfqq
->service_last
)
508 if (time_before(__cfqq
->service_last
, cfqq
->service_last
))
512 list_add(&cfqq
->cfq_list
, entry
);
516 * add to busy list of queues for service, trying to be fair in ordering
517 * the pending list according to last request service
520 cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
522 BUG_ON(cfq_cfqq_on_rr(cfqq
));
523 cfq_mark_cfqq_on_rr(cfqq
);
526 cfq_resort_rr_list(cfqq
, 0);
530 cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
532 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
533 cfq_clear_cfqq_on_rr(cfqq
);
534 list_move(&cfqq
->cfq_list
, &cfqd
->empty_list
);
536 BUG_ON(!cfqd
->busy_queues
);
541 * rb tree support functions
543 static inline void cfq_del_crq_rb(struct cfq_rq
*crq
)
545 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
546 struct cfq_data
*cfqd
= cfqq
->cfqd
;
547 const int sync
= cfq_crq_is_sync(crq
);
549 BUG_ON(!cfqq
->queued
[sync
]);
550 cfqq
->queued
[sync
]--;
552 cfq_update_next_crq(crq
);
554 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
555 RB_CLEAR_COLOR(&crq
->rb_node
);
557 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY(&cfqq
->sort_list
))
558 cfq_del_cfqq_rr(cfqd
, cfqq
);
561 static struct cfq_rq
*
562 __cfq_add_crq_rb(struct cfq_rq
*crq
)
564 struct rb_node
**p
= &crq
->cfq_queue
->sort_list
.rb_node
;
565 struct rb_node
*parent
= NULL
;
566 struct cfq_rq
*__crq
;
570 __crq
= rb_entry_crq(parent
);
572 if (crq
->rb_key
< __crq
->rb_key
)
574 else if (crq
->rb_key
> __crq
->rb_key
)
580 rb_link_node(&crq
->rb_node
, parent
, p
);
584 static void cfq_add_crq_rb(struct cfq_rq
*crq
)
586 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
587 struct cfq_data
*cfqd
= cfqq
->cfqd
;
588 struct request
*rq
= crq
->request
;
589 struct cfq_rq
*__alias
;
591 crq
->rb_key
= rq_rb_key(rq
);
592 cfqq
->queued
[cfq_crq_is_sync(crq
)]++;
595 * looks a little odd, but the first insert might return an alias.
596 * if that happens, put the alias on the dispatch list
598 while ((__alias
= __cfq_add_crq_rb(crq
)) != NULL
)
599 cfq_dispatch_insert(cfqd
->queue
, __alias
);
601 rb_insert_color(&crq
->rb_node
, &cfqq
->sort_list
);
603 if (!cfq_cfqq_on_rr(cfqq
))
604 cfq_add_cfqq_rr(cfqd
, cfqq
);
607 * check if this request is a better next-serve candidate
609 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
613 cfq_reposition_crq_rb(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
615 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
616 cfqq
->queued
[cfq_crq_is_sync(crq
)]--;
621 static struct request
*cfq_find_rq_rb(struct cfq_data
*cfqd
, sector_t sector
)
624 struct cfq_queue
*cfqq
= cfq_find_cfq_hash(cfqd
, current
->pid
, CFQ_KEY_ANY
);
630 n
= cfqq
->sort_list
.rb_node
;
632 struct cfq_rq
*crq
= rb_entry_crq(n
);
634 if (sector
< crq
->rb_key
)
636 else if (sector
> crq
->rb_key
)
646 static void cfq_activate_request(request_queue_t
*q
, struct request
*rq
)
648 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
650 cfqd
->rq_in_driver
++;
653 static void cfq_deactivate_request(request_queue_t
*q
, struct request
*rq
)
655 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
657 WARN_ON(!cfqd
->rq_in_driver
);
658 cfqd
->rq_in_driver
--;
661 static void cfq_remove_request(struct request
*rq
)
663 struct cfq_rq
*crq
= RQ_DATA(rq
);
665 list_del_init(&rq
->queuelist
);
667 cfq_del_crq_hash(crq
);
671 cfq_merge(request_queue_t
*q
, struct request
**req
, struct bio
*bio
)
673 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
674 struct request
*__rq
;
677 __rq
= cfq_find_rq_hash(cfqd
, bio
->bi_sector
);
678 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
679 ret
= ELEVATOR_BACK_MERGE
;
683 __rq
= cfq_find_rq_rb(cfqd
, bio
->bi_sector
+ bio_sectors(bio
));
684 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
685 ret
= ELEVATOR_FRONT_MERGE
;
689 return ELEVATOR_NO_MERGE
;
695 static void cfq_merged_request(request_queue_t
*q
, struct request
*req
)
697 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
698 struct cfq_rq
*crq
= RQ_DATA(req
);
700 cfq_del_crq_hash(crq
);
701 cfq_add_crq_hash(cfqd
, crq
);
703 if (rq_rb_key(req
) != crq
->rb_key
) {
704 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
706 cfq_update_next_crq(crq
);
707 cfq_reposition_crq_rb(cfqq
, crq
);
712 cfq_merged_requests(request_queue_t
*q
, struct request
*rq
,
713 struct request
*next
)
715 cfq_merged_request(q
, rq
);
718 * reposition in fifo if next is older than rq
720 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
721 time_before(next
->start_time
, rq
->start_time
))
722 list_move(&rq
->queuelist
, &next
->queuelist
);
724 cfq_remove_request(next
);
728 __cfq_set_active_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
732 * stop potential idle class queues waiting service
734 del_timer(&cfqd
->idle_class_timer
);
736 cfqq
->slice_start
= jiffies
;
738 cfqq
->slice_left
= 0;
739 cfq_clear_cfqq_must_alloc_slice(cfqq
);
740 cfq_clear_cfqq_fifo_expire(cfqq
);
741 cfq_clear_cfqq_expired(cfqq
);
744 cfqd
->active_queue
= cfqq
;
757 static int cfq_get_next_prio_level(struct cfq_data
*cfqd
)
766 for (p
= cfqd
->cur_prio
; p
<= cfqd
->cur_end_prio
; p
++) {
767 if (!list_empty(&cfqd
->rr_list
[p
])) {
776 if (++cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
777 cfqd
->cur_end_prio
= 0;
784 if (unlikely(prio
== -1))
787 BUG_ON(prio
>= CFQ_PRIO_LISTS
);
789 list_splice_init(&cfqd
->rr_list
[prio
], &cfqd
->cur_rr
);
791 cfqd
->cur_prio
= prio
+ 1;
792 if (cfqd
->cur_prio
> cfqd
->cur_end_prio
) {
793 cfqd
->cur_end_prio
= cfqd
->cur_prio
;
796 if (cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
798 cfqd
->cur_end_prio
= 0;
804 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
)
806 struct cfq_queue
*cfqq
;
809 * if current queue is expired but not done with its requests yet,
810 * wait for that to happen
812 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
813 if (cfq_cfqq_expired(cfqq
) && cfq_cfqq_dispatched(cfqq
))
818 * if current list is non-empty, grab first entry. if it is empty,
819 * get next prio level and grab first entry then if any are spliced
821 if (!list_empty(&cfqd
->cur_rr
) || cfq_get_next_prio_level(cfqd
) != -1)
822 cfqq
= list_entry_cfqq(cfqd
->cur_rr
.next
);
825 * if we have idle queues and no rt or be queues had pending
826 * requests, either allow immediate service if the grace period
827 * has passed or arm the idle grace timer
829 if (!cfqq
&& !list_empty(&cfqd
->idle_rr
)) {
830 unsigned long end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
832 if (time_after_eq(jiffies
, end
))
833 cfqq
= list_entry_cfqq(cfqd
->idle_rr
.next
);
835 mod_timer(&cfqd
->idle_class_timer
, end
);
838 __cfq_set_active_queue(cfqd
, cfqq
);
843 * current cfqq expired its slice (or was too idle), select new one
846 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
849 unsigned long now
= jiffies
;
851 if (cfq_cfqq_wait_request(cfqq
))
852 del_timer(&cfqd
->idle_slice_timer
);
854 if (!preempted
&& !cfq_cfqq_dispatched(cfqq
))
855 cfqq
->service_last
= now
;
857 cfq_clear_cfqq_must_dispatch(cfqq
);
858 cfq_clear_cfqq_wait_request(cfqq
);
861 * store what was left of this slice, if the queue idled out
864 if (time_after(now
, cfqq
->slice_end
))
865 cfqq
->slice_left
= now
- cfqq
->slice_end
;
867 cfqq
->slice_left
= 0;
869 if (cfq_cfqq_on_rr(cfqq
))
870 cfq_resort_rr_list(cfqq
, preempted
);
872 if (cfqq
== cfqd
->active_queue
)
873 cfqd
->active_queue
= NULL
;
875 if (cfqd
->active_cic
) {
876 put_io_context(cfqd
->active_cic
->ioc
);
877 cfqd
->active_cic
= NULL
;
880 cfqd
->dispatch_slice
= 0;
883 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, int preempted
)
885 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
889 * use deferred expiry, if there are requests in progress as
890 * not to disturb the slice of the next queue
892 if (cfq_cfqq_dispatched(cfqq
))
893 cfq_mark_cfqq_expired(cfqq
);
895 __cfq_slice_expired(cfqd
, cfqq
, preempted
);
899 static int cfq_arm_slice_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
902 WARN_ON(!RB_EMPTY(&cfqq
->sort_list
));
903 WARN_ON(cfqq
!= cfqd
->active_queue
);
906 * idle is disabled, either manually or by past process history
908 if (!cfqd
->cfq_slice_idle
)
910 if (!cfq_cfqq_idle_window(cfqq
))
913 * task has exited, don't wait
915 if (cfqd
->active_cic
&& !cfqd
->active_cic
->ioc
->task
)
918 cfq_mark_cfqq_must_dispatch(cfqq
);
919 cfq_mark_cfqq_wait_request(cfqq
);
921 if (!timer_pending(&cfqd
->idle_slice_timer
)) {
922 unsigned long slice_left
= min(cfqq
->slice_end
- 1, (unsigned long) cfqd
->cfq_slice_idle
);
924 cfqd
->idle_slice_timer
.expires
= jiffies
+ slice_left
;
925 add_timer(&cfqd
->idle_slice_timer
);
931 static void cfq_dispatch_insert(request_queue_t
*q
, struct cfq_rq
*crq
)
933 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
934 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
936 cfqq
->next_crq
= cfq_find_next_crq(cfqd
, cfqq
, crq
);
937 cfq_remove_request(crq
->request
);
938 cfqq
->on_dispatch
[cfq_crq_is_sync(crq
)]++;
939 elv_dispatch_sort(q
, crq
->request
);
943 * return expired entry, or NULL to just start from scratch in rbtree
945 static inline struct cfq_rq
*cfq_check_fifo(struct cfq_queue
*cfqq
)
947 struct cfq_data
*cfqd
= cfqq
->cfqd
;
951 if (cfq_cfqq_fifo_expire(cfqq
))
954 if (!list_empty(&cfqq
->fifo
)) {
955 int fifo
= cfq_cfqq_class_sync(cfqq
);
957 crq
= RQ_DATA(list_entry_fifo(cfqq
->fifo
.next
));
959 if (time_after(jiffies
, rq
->start_time
+ cfqd
->cfq_fifo_expire
[fifo
])) {
960 cfq_mark_cfqq_fifo_expire(cfqq
);
969 * Scale schedule slice based on io priority. Use the sync time slice only
970 * if a queue is marked sync and has sync io queued. A sync queue with async
971 * io only, should not get full sync slice length.
974 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
976 const int base_slice
= cfqd
->cfq_slice
[cfq_cfqq_sync(cfqq
)];
978 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
980 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - cfqq
->ioprio
));
984 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
986 cfqq
->slice_end
= cfq_prio_to_slice(cfqd
, cfqq
) + jiffies
;
990 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
992 const int base_rq
= cfqd
->cfq_slice_async_rq
;
994 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
996 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1000 * get next queue for service
1002 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
, int force
)
1004 unsigned long now
= jiffies
;
1005 struct cfq_queue
*cfqq
;
1007 cfqq
= cfqd
->active_queue
;
1011 if (cfq_cfqq_expired(cfqq
))
1017 if (!cfq_cfqq_must_dispatch(cfqq
) && time_after(now
, cfqq
->slice_end
))
1021 * if queue has requests, dispatch one. if not, check if
1022 * enough slice is left to wait for one
1024 if (!RB_EMPTY(&cfqq
->sort_list
))
1026 else if (!force
&& cfq_cfqq_class_sync(cfqq
) &&
1027 time_before(now
, cfqq
->slice_end
)) {
1028 if (cfq_arm_slice_timer(cfqd
, cfqq
))
1033 cfq_slice_expired(cfqd
, 0);
1035 cfqq
= cfq_set_active_queue(cfqd
);
1041 __cfq_dispatch_requests(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1046 BUG_ON(RB_EMPTY(&cfqq
->sort_list
));
1052 * follow expired path, else get first next available
1054 if ((crq
= cfq_check_fifo(cfqq
)) == NULL
)
1055 crq
= cfqq
->next_crq
;
1058 * finally, insert request into driver dispatch list
1060 cfq_dispatch_insert(cfqd
->queue
, crq
);
1062 cfqd
->dispatch_slice
++;
1065 if (!cfqd
->active_cic
) {
1066 atomic_inc(&crq
->io_context
->ioc
->refcount
);
1067 cfqd
->active_cic
= crq
->io_context
;
1070 if (RB_EMPTY(&cfqq
->sort_list
))
1073 } while (dispatched
< max_dispatch
);
1076 * if slice end isn't set yet, set it. if at least one request was
1077 * sync, use the sync time slice value
1079 if (!cfqq
->slice_end
)
1080 cfq_set_prio_slice(cfqd
, cfqq
);
1083 * expire an async queue immediately if it has used up its slice. idle
1084 * queue always expire after 1 dispatch round.
1086 if ((!cfq_cfqq_sync(cfqq
) &&
1087 cfqd
->dispatch_slice
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1088 cfq_class_idle(cfqq
))
1089 cfq_slice_expired(cfqd
, 0);
1095 cfq_dispatch_requests(request_queue_t
*q
, int force
)
1097 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1098 struct cfq_queue
*cfqq
;
1100 if (!cfqd
->busy_queues
)
1103 cfqq
= cfq_select_queue(cfqd
, force
);
1108 * if idle window is disabled, allow queue buildup
1110 if (!cfq_cfqq_idle_window(cfqq
) &&
1111 cfqd
->rq_in_driver
>= cfqd
->cfq_max_depth
)
1114 cfq_clear_cfqq_must_dispatch(cfqq
);
1115 cfq_clear_cfqq_wait_request(cfqq
);
1116 del_timer(&cfqd
->idle_slice_timer
);
1119 max_dispatch
= cfqd
->cfq_quantum
;
1120 if (cfq_class_idle(cfqq
))
1123 max_dispatch
= INT_MAX
;
1125 return __cfq_dispatch_requests(cfqd
, cfqq
, max_dispatch
);
1132 * task holds one reference to the queue, dropped when task exits. each crq
1133 * in-flight on this queue also holds a reference, dropped when crq is freed.
1135 * queue lock must be held here.
1137 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1139 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1141 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1143 if (!atomic_dec_and_test(&cfqq
->ref
))
1146 BUG_ON(rb_first(&cfqq
->sort_list
));
1147 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1148 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1150 if (unlikely(cfqd
->active_queue
== cfqq
)) {
1151 __cfq_slice_expired(cfqd
, cfqq
, 0);
1152 cfq_schedule_dispatch(cfqd
);
1155 cfq_put_cfqd(cfqq
->cfqd
);
1158 * it's on the empty list and still hashed
1160 list_del(&cfqq
->cfq_list
);
1161 hlist_del(&cfqq
->cfq_hash
);
1162 kmem_cache_free(cfq_pool
, cfqq
);
1165 static inline struct cfq_queue
*
1166 __cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned int prio
,
1169 struct hlist_head
*hash_list
= &cfqd
->cfq_hash
[hashval
];
1170 struct hlist_node
*entry
, *next
;
1172 hlist_for_each_safe(entry
, next
, hash_list
) {
1173 struct cfq_queue
*__cfqq
= list_entry_qhash(entry
);
1174 const unsigned short __p
= IOPRIO_PRIO_VALUE(__cfqq
->ioprio_class
, __cfqq
->ioprio
);
1176 if (__cfqq
->key
== key
&& (__p
== prio
|| prio
== CFQ_KEY_ANY
))
1183 static struct cfq_queue
*
1184 cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned short prio
)
1186 return __cfq_find_cfq_hash(cfqd
, key
, prio
, hash_long(key
, CFQ_QHASH_SHIFT
));
1189 static void cfq_free_io_context(struct cfq_io_context
*cic
)
1191 struct cfq_io_context
*__cic
;
1192 struct list_head
*entry
, *next
;
1194 list_for_each_safe(entry
, next
, &cic
->list
) {
1195 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1196 kmem_cache_free(cfq_ioc_pool
, __cic
);
1199 kmem_cache_free(cfq_ioc_pool
, cic
);
1203 * Called with interrupts disabled
1205 static void cfq_exit_single_io_context(struct cfq_io_context
*cic
)
1207 struct cfq_data
*cfqd
= cic
->cfqq
->cfqd
;
1208 request_queue_t
*q
= cfqd
->queue
;
1210 WARN_ON(!irqs_disabled());
1212 spin_lock(q
->queue_lock
);
1214 if (unlikely(cic
->cfqq
== cfqd
->active_queue
)) {
1215 __cfq_slice_expired(cfqd
, cic
->cfqq
, 0);
1216 cfq_schedule_dispatch(cfqd
);
1219 cfq_put_queue(cic
->cfqq
);
1221 spin_unlock(q
->queue_lock
);
1225 * Another task may update the task cic list, if it is doing a queue lookup
1226 * on its behalf. cfq_cic_lock excludes such concurrent updates
1228 static void cfq_exit_io_context(struct cfq_io_context
*cic
)
1230 struct cfq_io_context
*__cic
;
1231 struct list_head
*entry
;
1232 unsigned long flags
;
1234 local_irq_save(flags
);
1237 * put the reference this task is holding to the various queues
1239 list_for_each(entry
, &cic
->list
) {
1240 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1241 cfq_exit_single_io_context(__cic
);
1244 cfq_exit_single_io_context(cic
);
1245 local_irq_restore(flags
);
1248 static struct cfq_io_context
*
1249 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1251 struct cfq_io_context
*cic
= kmem_cache_alloc(cfq_ioc_pool
, gfp_mask
);
1254 INIT_LIST_HEAD(&cic
->list
);
1257 cic
->last_end_request
= jiffies
;
1258 cic
->ttime_total
= 0;
1259 cic
->ttime_samples
= 0;
1260 cic
->ttime_mean
= 0;
1261 cic
->dtor
= cfq_free_io_context
;
1262 cic
->exit
= cfq_exit_io_context
;
1268 static void cfq_init_prio_data(struct cfq_queue
*cfqq
)
1270 struct task_struct
*tsk
= current
;
1273 if (!cfq_cfqq_prio_changed(cfqq
))
1276 ioprio_class
= IOPRIO_PRIO_CLASS(tsk
->ioprio
);
1277 switch (ioprio_class
) {
1279 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1280 case IOPRIO_CLASS_NONE
:
1282 * no prio set, place us in the middle of the BE classes
1284 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1285 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1287 case IOPRIO_CLASS_RT
:
1288 cfqq
->ioprio
= task_ioprio(tsk
);
1289 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1291 case IOPRIO_CLASS_BE
:
1292 cfqq
->ioprio
= task_ioprio(tsk
);
1293 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1295 case IOPRIO_CLASS_IDLE
:
1296 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
1298 cfq_clear_cfqq_idle_window(cfqq
);
1303 * keep track of original prio settings in case we have to temporarily
1304 * elevate the priority of this queue
1306 cfqq
->org_ioprio
= cfqq
->ioprio
;
1307 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
1309 if (cfq_cfqq_on_rr(cfqq
))
1310 cfq_resort_rr_list(cfqq
, 0);
1312 cfq_clear_cfqq_prio_changed(cfqq
);
1315 static inline void changed_ioprio(struct cfq_queue
*cfqq
)
1318 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1320 spin_lock(cfqd
->queue
->queue_lock
);
1321 cfq_mark_cfqq_prio_changed(cfqq
);
1322 cfq_init_prio_data(cfqq
);
1323 spin_unlock(cfqd
->queue
->queue_lock
);
1328 * callback from sys_ioprio_set, irqs are disabled
1330 static int cfq_ioc_set_ioprio(struct io_context
*ioc
, unsigned int ioprio
)
1332 struct cfq_io_context
*cic
= ioc
->cic
;
1334 changed_ioprio(cic
->cfqq
);
1336 list_for_each_entry(cic
, &cic
->list
, list
)
1337 changed_ioprio(cic
->cfqq
);
1342 static struct cfq_queue
*
1343 cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, unsigned short ioprio
,
1346 const int hashval
= hash_long(key
, CFQ_QHASH_SHIFT
);
1347 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1350 cfqq
= __cfq_find_cfq_hash(cfqd
, key
, ioprio
, hashval
);
1356 } else if (gfp_mask
& __GFP_WAIT
) {
1357 spin_unlock_irq(cfqd
->queue
->queue_lock
);
1358 new_cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1359 spin_lock_irq(cfqd
->queue
->queue_lock
);
1362 cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1367 memset(cfqq
, 0, sizeof(*cfqq
));
1369 INIT_HLIST_NODE(&cfqq
->cfq_hash
);
1370 INIT_LIST_HEAD(&cfqq
->cfq_list
);
1371 RB_CLEAR_ROOT(&cfqq
->sort_list
);
1372 INIT_LIST_HEAD(&cfqq
->fifo
);
1375 hlist_add_head(&cfqq
->cfq_hash
, &cfqd
->cfq_hash
[hashval
]);
1376 atomic_set(&cfqq
->ref
, 0);
1378 atomic_inc(&cfqd
->ref
);
1379 cfqq
->service_last
= 0;
1381 * set ->slice_left to allow preemption for a new process
1383 cfqq
->slice_left
= 2 * cfqd
->cfq_slice_idle
;
1384 cfq_mark_cfqq_idle_window(cfqq
);
1385 cfq_mark_cfqq_prio_changed(cfqq
);
1386 cfq_init_prio_data(cfqq
);
1390 kmem_cache_free(cfq_pool
, new_cfqq
);
1392 atomic_inc(&cfqq
->ref
);
1394 WARN_ON((gfp_mask
& __GFP_WAIT
) && !cfqq
);
1399 * Setup general io context and cfq io context. There can be several cfq
1400 * io contexts per general io context, if this process is doing io to more
1401 * than one device managed by cfq. Note that caller is holding a reference to
1402 * cfqq, so we don't need to worry about it disappearing
1404 static struct cfq_io_context
*
1405 cfq_get_io_context(struct cfq_data
*cfqd
, pid_t pid
, gfp_t gfp_mask
)
1407 struct io_context
*ioc
= NULL
;
1408 struct cfq_io_context
*cic
;
1410 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1412 ioc
= get_io_context(gfp_mask
);
1416 if ((cic
= ioc
->cic
) == NULL
) {
1417 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1423 * manually increment generic io_context usage count, it
1424 * cannot go away since we are already holding one ref to it
1427 ioc
->set_ioprio
= cfq_ioc_set_ioprio
;
1430 atomic_inc(&cfqd
->ref
);
1432 struct cfq_io_context
*__cic
;
1435 * the first cic on the list is actually the head itself
1437 if (cic
->key
== cfqd
)
1441 * cic exists, check if we already are there. linear search
1442 * should be ok here, the list will usually not be more than
1443 * 1 or a few entries long
1445 list_for_each_entry(__cic
, &cic
->list
, list
) {
1447 * this process is already holding a reference to
1448 * this queue, so no need to get one more
1450 if (__cic
->key
== cfqd
) {
1457 * nope, process doesn't have a cic assoicated with this
1458 * cfqq yet. get a new one and add to list
1460 __cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1466 atomic_inc(&cfqd
->ref
);
1467 list_add(&__cic
->list
, &cic
->list
);
1474 put_io_context(ioc
);
1479 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
1481 unsigned long elapsed
, ttime
;
1484 * if this context already has stuff queued, thinktime is from
1485 * last queue not last end
1488 if (time_after(cic
->last_end_request
, cic
->last_queue
))
1489 elapsed
= jiffies
- cic
->last_end_request
;
1491 elapsed
= jiffies
- cic
->last_queue
;
1493 elapsed
= jiffies
- cic
->last_end_request
;
1496 ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
1498 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
1499 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
1500 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
1503 #define sample_valid(samples) ((samples) > 80)
1506 * Disable idle window if the process thinks too long or seeks so much that
1510 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1511 struct cfq_io_context
*cic
)
1513 int enable_idle
= cfq_cfqq_idle_window(cfqq
);
1515 if (!cic
->ioc
->task
|| !cfqd
->cfq_slice_idle
)
1517 else if (sample_valid(cic
->ttime_samples
)) {
1518 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
1525 cfq_mark_cfqq_idle_window(cfqq
);
1527 cfq_clear_cfqq_idle_window(cfqq
);
1532 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1533 * no or if we aren't sure, a 1 will cause a preempt.
1536 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
1539 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1541 if (cfq_class_idle(new_cfqq
))
1547 if (cfq_class_idle(cfqq
))
1549 if (!cfq_cfqq_wait_request(new_cfqq
))
1552 * if it doesn't have slice left, forget it
1554 if (new_cfqq
->slice_left
< cfqd
->cfq_slice_idle
)
1556 if (cfq_crq_is_sync(crq
) && !cfq_cfqq_sync(cfqq
))
1563 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1564 * let it have half of its nominal slice.
1566 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1568 struct cfq_queue
*__cfqq
, *next
;
1570 list_for_each_entry_safe(__cfqq
, next
, &cfqd
->cur_rr
, cfq_list
)
1571 cfq_resort_rr_list(__cfqq
, 1);
1573 if (!cfqq
->slice_left
)
1574 cfqq
->slice_left
= cfq_prio_to_slice(cfqd
, cfqq
) / 2;
1576 cfqq
->slice_end
= cfqq
->slice_left
+ jiffies
;
1577 __cfq_slice_expired(cfqd
, cfqq
, 1);
1578 __cfq_set_active_queue(cfqd
, cfqq
);
1582 * should really be a ll_rw_blk.c helper
1584 static void cfq_start_queueing(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1586 request_queue_t
*q
= cfqd
->queue
;
1588 if (!blk_queue_plugged(q
))
1591 __generic_unplug_device(q
);
1595 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1596 * something we should do about it
1599 cfq_crq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1602 struct cfq_io_context
*cic
;
1604 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
1607 * we never wait for an async request and we don't allow preemption
1608 * of an async request. so just return early
1610 if (!cfq_crq_is_sync(crq
))
1613 cic
= crq
->io_context
;
1615 cfq_update_io_thinktime(cfqd
, cic
);
1616 cfq_update_idle_window(cfqd
, cfqq
, cic
);
1618 cic
->last_queue
= jiffies
;
1620 if (cfqq
== cfqd
->active_queue
) {
1622 * if we are waiting for a request for this queue, let it rip
1623 * immediately and flag that we must not expire this queue
1626 if (cfq_cfqq_wait_request(cfqq
)) {
1627 cfq_mark_cfqq_must_dispatch(cfqq
);
1628 del_timer(&cfqd
->idle_slice_timer
);
1629 cfq_start_queueing(cfqd
, cfqq
);
1631 } else if (cfq_should_preempt(cfqd
, cfqq
, crq
)) {
1633 * not the active queue - expire current slice if it is
1634 * idle and has expired it's mean thinktime or this new queue
1635 * has some old slice time left and is of higher priority
1637 cfq_preempt_queue(cfqd
, cfqq
);
1638 cfq_mark_cfqq_must_dispatch(cfqq
);
1639 cfq_start_queueing(cfqd
, cfqq
);
1643 static void cfq_insert_request(request_queue_t
*q
, struct request
*rq
)
1645 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1646 struct cfq_rq
*crq
= RQ_DATA(rq
);
1647 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1649 cfq_init_prio_data(cfqq
);
1651 cfq_add_crq_rb(crq
);
1653 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
1655 if (rq_mergeable(rq
))
1656 cfq_add_crq_hash(cfqd
, crq
);
1658 cfq_crq_enqueued(cfqd
, cfqq
, crq
);
1661 static void cfq_completed_request(request_queue_t
*q
, struct request
*rq
)
1663 struct cfq_rq
*crq
= RQ_DATA(rq
);
1664 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1665 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1666 const int sync
= cfq_crq_is_sync(crq
);
1671 WARN_ON(!cfqd
->rq_in_driver
);
1672 WARN_ON(!cfqq
->on_dispatch
[sync
]);
1673 cfqd
->rq_in_driver
--;
1674 cfqq
->on_dispatch
[sync
]--;
1676 if (!cfq_class_idle(cfqq
))
1677 cfqd
->last_end_request
= now
;
1679 if (!cfq_cfqq_dispatched(cfqq
)) {
1680 if (cfq_cfqq_on_rr(cfqq
)) {
1681 cfqq
->service_last
= now
;
1682 cfq_resort_rr_list(cfqq
, 0);
1684 if (cfq_cfqq_expired(cfqq
)) {
1685 __cfq_slice_expired(cfqd
, cfqq
, 0);
1686 cfq_schedule_dispatch(cfqd
);
1690 if (cfq_crq_is_sync(crq
))
1691 crq
->io_context
->last_end_request
= now
;
1694 static struct request
*
1695 cfq_former_request(request_queue_t
*q
, struct request
*rq
)
1697 struct cfq_rq
*crq
= RQ_DATA(rq
);
1698 struct rb_node
*rbprev
= rb_prev(&crq
->rb_node
);
1701 return rb_entry_crq(rbprev
)->request
;
1706 static struct request
*
1707 cfq_latter_request(request_queue_t
*q
, struct request
*rq
)
1709 struct cfq_rq
*crq
= RQ_DATA(rq
);
1710 struct rb_node
*rbnext
= rb_next(&crq
->rb_node
);
1713 return rb_entry_crq(rbnext
)->request
;
1719 * we temporarily boost lower priority queues if they are holding fs exclusive
1720 * resources. they are boosted to normal prio (CLASS_BE/4)
1722 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
1724 const int ioprio_class
= cfqq
->ioprio_class
;
1725 const int ioprio
= cfqq
->ioprio
;
1727 if (has_fs_excl()) {
1729 * boost idle prio on transactions that would lock out other
1730 * users of the filesystem
1732 if (cfq_class_idle(cfqq
))
1733 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1734 if (cfqq
->ioprio
> IOPRIO_NORM
)
1735 cfqq
->ioprio
= IOPRIO_NORM
;
1738 * check if we need to unboost the queue
1740 if (cfqq
->ioprio_class
!= cfqq
->org_ioprio_class
)
1741 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
1742 if (cfqq
->ioprio
!= cfqq
->org_ioprio
)
1743 cfqq
->ioprio
= cfqq
->org_ioprio
;
1747 * refile between round-robin lists if we moved the priority class
1749 if ((ioprio_class
!= cfqq
->ioprio_class
|| ioprio
!= cfqq
->ioprio
) &&
1750 cfq_cfqq_on_rr(cfqq
))
1751 cfq_resort_rr_list(cfqq
, 0);
1754 static inline pid_t
cfq_queue_pid(struct task_struct
*task
, int rw
)
1756 if (rw
== READ
|| process_sync(task
))
1759 return CFQ_KEY_ASYNC
;
1763 __cfq_may_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1764 struct task_struct
*task
, int rw
)
1767 if ((cfq_cfqq_wait_request(cfqq
) || cfq_cfqq_must_alloc(cfqq
)) &&
1768 !cfq_cfqq_must_alloc_slice(cfqq
)) {
1769 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1770 return ELV_MQUEUE_MUST
;
1773 return ELV_MQUEUE_MAY
;
1775 if (!cfqq
|| task
->flags
& PF_MEMALLOC
)
1776 return ELV_MQUEUE_MAY
;
1777 if (!cfqq
->allocated
[rw
] || cfq_cfqq_must_alloc(cfqq
)) {
1778 if (cfq_cfqq_wait_request(cfqq
))
1779 return ELV_MQUEUE_MUST
;
1782 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1783 * can quickly flood the queue with writes from a single task
1785 if (rw
== READ
|| !cfq_cfqq_must_alloc_slice(cfqq
)) {
1786 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1787 return ELV_MQUEUE_MUST
;
1790 return ELV_MQUEUE_MAY
;
1792 if (cfq_class_idle(cfqq
))
1793 return ELV_MQUEUE_NO
;
1794 if (cfqq
->allocated
[rw
] >= cfqd
->max_queued
) {
1795 struct io_context
*ioc
= get_io_context(GFP_ATOMIC
);
1796 int ret
= ELV_MQUEUE_NO
;
1798 if (ioc
&& ioc
->nr_batch_requests
)
1799 ret
= ELV_MQUEUE_MAY
;
1801 put_io_context(ioc
);
1805 return ELV_MQUEUE_MAY
;
1809 static int cfq_may_queue(request_queue_t
*q
, int rw
, struct bio
*bio
)
1811 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1812 struct task_struct
*tsk
= current
;
1813 struct cfq_queue
*cfqq
;
1816 * don't force setup of a queue from here, as a call to may_queue
1817 * does not necessarily imply that a request actually will be queued.
1818 * so just lookup a possibly existing queue, or return 'may queue'
1821 cfqq
= cfq_find_cfq_hash(cfqd
, cfq_queue_pid(tsk
, rw
), tsk
->ioprio
);
1823 cfq_init_prio_data(cfqq
);
1824 cfq_prio_boost(cfqq
);
1826 return __cfq_may_queue(cfqd
, cfqq
, tsk
, rw
);
1829 return ELV_MQUEUE_MAY
;
1832 static void cfq_check_waiters(request_queue_t
*q
, struct cfq_queue
*cfqq
)
1834 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1835 struct request_list
*rl
= &q
->rq
;
1837 if (cfqq
->allocated
[READ
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
1839 if (waitqueue_active(&rl
->wait
[READ
]))
1840 wake_up(&rl
->wait
[READ
]);
1843 if (cfqq
->allocated
[WRITE
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
1845 if (waitqueue_active(&rl
->wait
[WRITE
]))
1846 wake_up(&rl
->wait
[WRITE
]);
1851 * queue lock held here
1853 static void cfq_put_request(request_queue_t
*q
, struct request
*rq
)
1855 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1856 struct cfq_rq
*crq
= RQ_DATA(rq
);
1859 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1860 const int rw
= rq_data_dir(rq
);
1862 BUG_ON(!cfqq
->allocated
[rw
]);
1863 cfqq
->allocated
[rw
]--;
1865 put_io_context(crq
->io_context
->ioc
);
1867 mempool_free(crq
, cfqd
->crq_pool
);
1868 rq
->elevator_private
= NULL
;
1870 cfq_check_waiters(q
, cfqq
);
1871 cfq_put_queue(cfqq
);
1876 * Allocate cfq data structures associated with this request.
1879 cfq_set_request(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
,
1882 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1883 struct task_struct
*tsk
= current
;
1884 struct cfq_io_context
*cic
;
1885 const int rw
= rq_data_dir(rq
);
1886 pid_t key
= cfq_queue_pid(tsk
, rw
);
1887 struct cfq_queue
*cfqq
;
1889 unsigned long flags
;
1891 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1893 cic
= cfq_get_io_context(cfqd
, key
, gfp_mask
);
1895 spin_lock_irqsave(q
->queue_lock
, flags
);
1901 cfqq
= cfq_get_queue(cfqd
, key
, tsk
->ioprio
, gfp_mask
);
1909 cfqq
->allocated
[rw
]++;
1910 cfq_clear_cfqq_must_alloc(cfqq
);
1911 cfqd
->rq_starved
= 0;
1912 atomic_inc(&cfqq
->ref
);
1913 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1915 crq
= mempool_alloc(cfqd
->crq_pool
, gfp_mask
);
1917 RB_CLEAR(&crq
->rb_node
);
1920 INIT_HLIST_NODE(&crq
->hash
);
1921 crq
->cfq_queue
= cfqq
;
1922 crq
->io_context
= cic
;
1924 if (rw
== READ
|| process_sync(tsk
))
1925 cfq_mark_crq_is_sync(crq
);
1927 cfq_clear_crq_is_sync(crq
);
1929 rq
->elevator_private
= crq
;
1933 spin_lock_irqsave(q
->queue_lock
, flags
);
1934 cfqq
->allocated
[rw
]--;
1935 if (!(cfqq
->allocated
[0] + cfqq
->allocated
[1]))
1936 cfq_mark_cfqq_must_alloc(cfqq
);
1937 cfq_put_queue(cfqq
);
1940 put_io_context(cic
->ioc
);
1942 * mark us rq allocation starved. we need to kickstart the process
1943 * ourselves if there are no pending requests that can do it for us.
1944 * that would be an extremely rare OOM situation
1946 cfqd
->rq_starved
= 1;
1947 cfq_schedule_dispatch(cfqd
);
1948 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1952 static void cfq_kick_queue(void *data
)
1954 request_queue_t
*q
= data
;
1955 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1956 unsigned long flags
;
1958 spin_lock_irqsave(q
->queue_lock
, flags
);
1960 if (cfqd
->rq_starved
) {
1961 struct request_list
*rl
= &q
->rq
;
1964 * we aren't guaranteed to get a request after this, but we
1965 * have to be opportunistic
1968 if (waitqueue_active(&rl
->wait
[READ
]))
1969 wake_up(&rl
->wait
[READ
]);
1970 if (waitqueue_active(&rl
->wait
[WRITE
]))
1971 wake_up(&rl
->wait
[WRITE
]);
1976 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1980 * Timer running if the active_queue is currently idling inside its time slice
1982 static void cfq_idle_slice_timer(unsigned long data
)
1984 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
1985 struct cfq_queue
*cfqq
;
1986 unsigned long flags
;
1988 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1990 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
1991 unsigned long now
= jiffies
;
1996 if (time_after(now
, cfqq
->slice_end
))
2000 * only expire and reinvoke request handler, if there are
2001 * other queues with pending requests
2003 if (!cfqd
->busy_queues
) {
2004 cfqd
->idle_slice_timer
.expires
= min(now
+ cfqd
->cfq_slice_idle
, cfqq
->slice_end
);
2005 add_timer(&cfqd
->idle_slice_timer
);
2010 * not expired and it has a request pending, let it dispatch
2012 if (!RB_EMPTY(&cfqq
->sort_list
)) {
2013 cfq_mark_cfqq_must_dispatch(cfqq
);
2018 cfq_slice_expired(cfqd
, 0);
2020 cfq_schedule_dispatch(cfqd
);
2022 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2026 * Timer running if an idle class queue is waiting for service
2028 static void cfq_idle_class_timer(unsigned long data
)
2030 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2031 unsigned long flags
, end
;
2033 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2036 * race with a non-idle queue, reset timer
2038 end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
2039 if (!time_after_eq(jiffies
, end
)) {
2040 cfqd
->idle_class_timer
.expires
= end
;
2041 add_timer(&cfqd
->idle_class_timer
);
2043 cfq_schedule_dispatch(cfqd
);
2045 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2048 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2050 del_timer_sync(&cfqd
->idle_slice_timer
);
2051 del_timer_sync(&cfqd
->idle_class_timer
);
2052 blk_sync_queue(cfqd
->queue
);
2055 static void cfq_put_cfqd(struct cfq_data
*cfqd
)
2057 request_queue_t
*q
= cfqd
->queue
;
2059 if (!atomic_dec_and_test(&cfqd
->ref
))
2062 cfq_shutdown_timer_wq(cfqd
);
2065 mempool_destroy(cfqd
->crq_pool
);
2066 kfree(cfqd
->crq_hash
);
2067 kfree(cfqd
->cfq_hash
);
2071 static void cfq_exit_queue(elevator_t
*e
)
2073 struct cfq_data
*cfqd
= e
->elevator_data
;
2075 cfq_shutdown_timer_wq(cfqd
);
2079 static int cfq_init_queue(request_queue_t
*q
, elevator_t
*e
)
2081 struct cfq_data
*cfqd
;
2084 cfqd
= kmalloc(sizeof(*cfqd
), GFP_KERNEL
);
2088 memset(cfqd
, 0, sizeof(*cfqd
));
2090 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2091 INIT_LIST_HEAD(&cfqd
->rr_list
[i
]);
2093 INIT_LIST_HEAD(&cfqd
->busy_rr
);
2094 INIT_LIST_HEAD(&cfqd
->cur_rr
);
2095 INIT_LIST_HEAD(&cfqd
->idle_rr
);
2096 INIT_LIST_HEAD(&cfqd
->empty_list
);
2098 cfqd
->crq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_MHASH_ENTRIES
, GFP_KERNEL
);
2099 if (!cfqd
->crq_hash
)
2102 cfqd
->cfq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_QHASH_ENTRIES
, GFP_KERNEL
);
2103 if (!cfqd
->cfq_hash
)
2106 cfqd
->crq_pool
= mempool_create(BLKDEV_MIN_RQ
, mempool_alloc_slab
, mempool_free_slab
, crq_pool
);
2107 if (!cfqd
->crq_pool
)
2110 for (i
= 0; i
< CFQ_MHASH_ENTRIES
; i
++)
2111 INIT_HLIST_HEAD(&cfqd
->crq_hash
[i
]);
2112 for (i
= 0; i
< CFQ_QHASH_ENTRIES
; i
++)
2113 INIT_HLIST_HEAD(&cfqd
->cfq_hash
[i
]);
2115 e
->elevator_data
= cfqd
;
2118 atomic_inc(&q
->refcnt
);
2120 cfqd
->max_queued
= q
->nr_requests
/ 4;
2121 q
->nr_batching
= cfq_queued
;
2123 init_timer(&cfqd
->idle_slice_timer
);
2124 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
2125 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
2127 init_timer(&cfqd
->idle_class_timer
);
2128 cfqd
->idle_class_timer
.function
= cfq_idle_class_timer
;
2129 cfqd
->idle_class_timer
.data
= (unsigned long) cfqd
;
2131 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
, q
);
2133 atomic_set(&cfqd
->ref
, 1);
2135 cfqd
->cfq_queued
= cfq_queued
;
2136 cfqd
->cfq_quantum
= cfq_quantum
;
2137 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
2138 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
2139 cfqd
->cfq_back_max
= cfq_back_max
;
2140 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
2141 cfqd
->cfq_slice
[0] = cfq_slice_async
;
2142 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
2143 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
2144 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
2145 cfqd
->cfq_max_depth
= cfq_max_depth
;
2149 kfree(cfqd
->cfq_hash
);
2151 kfree(cfqd
->crq_hash
);
2157 static void cfq_slab_kill(void)
2160 kmem_cache_destroy(crq_pool
);
2162 kmem_cache_destroy(cfq_pool
);
2164 kmem_cache_destroy(cfq_ioc_pool
);
2167 static int __init
cfq_slab_setup(void)
2169 crq_pool
= kmem_cache_create("crq_pool", sizeof(struct cfq_rq
), 0, 0,
2174 cfq_pool
= kmem_cache_create("cfq_pool", sizeof(struct cfq_queue
), 0, 0,
2179 cfq_ioc_pool
= kmem_cache_create("cfq_ioc_pool",
2180 sizeof(struct cfq_io_context
), 0, 0, NULL
, NULL
);
2191 * sysfs parts below -->
2193 struct cfq_fs_entry
{
2194 struct attribute attr
;
2195 ssize_t (*show
)(struct cfq_data
*, char *);
2196 ssize_t (*store
)(struct cfq_data
*, const char *, size_t);
2200 cfq_var_show(unsigned int var
, char *page
)
2202 return sprintf(page
, "%d\n", var
);
2206 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
2208 char *p
= (char *) page
;
2210 *var
= simple_strtoul(p
, &p
, 10);
2214 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2215 static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2217 unsigned int __data = __VAR; \
2219 __data = jiffies_to_msecs(__data); \
2220 return cfq_var_show(__data, (page)); \
2222 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
2223 SHOW_FUNCTION(cfq_queued_show
, cfqd
->cfq_queued
, 0);
2224 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
2225 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
2226 SHOW_FUNCTION(cfq_back_max_show
, cfqd
->cfq_back_max
, 0);
2227 SHOW_FUNCTION(cfq_back_penalty_show
, cfqd
->cfq_back_penalty
, 0);
2228 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
2229 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
2230 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
2231 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
2232 SHOW_FUNCTION(cfq_max_depth_show
, cfqd
->cfq_max_depth
, 0);
2233 #undef SHOW_FUNCTION
2235 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2236 static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2238 unsigned int __data; \
2239 int ret = cfq_var_store(&__data, (page), count); \
2240 if (__data < (MIN)) \
2242 else if (__data > (MAX)) \
2245 *(__PTR) = msecs_to_jiffies(__data); \
2247 *(__PTR) = __data; \
2250 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
2251 STORE_FUNCTION(cfq_queued_store
, &cfqd
->cfq_queued
, 1, UINT_MAX
, 0);
2252 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1, UINT_MAX
, 1);
2253 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1, UINT_MAX
, 1);
2254 STORE_FUNCTION(cfq_back_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
2255 STORE_FUNCTION(cfq_back_penalty_store
, &cfqd
->cfq_back_penalty
, 1, UINT_MAX
, 0);
2256 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
2257 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
2258 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
2259 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1, UINT_MAX
, 0);
2260 STORE_FUNCTION(cfq_max_depth_store
, &cfqd
->cfq_max_depth
, 1, UINT_MAX
, 0);
2261 #undef STORE_FUNCTION
2263 static struct cfq_fs_entry cfq_quantum_entry
= {
2264 .attr
= {.name
= "quantum", .mode
= S_IRUGO
| S_IWUSR
},
2265 .show
= cfq_quantum_show
,
2266 .store
= cfq_quantum_store
,
2268 static struct cfq_fs_entry cfq_queued_entry
= {
2269 .attr
= {.name
= "queued", .mode
= S_IRUGO
| S_IWUSR
},
2270 .show
= cfq_queued_show
,
2271 .store
= cfq_queued_store
,
2273 static struct cfq_fs_entry cfq_fifo_expire_sync_entry
= {
2274 .attr
= {.name
= "fifo_expire_sync", .mode
= S_IRUGO
| S_IWUSR
},
2275 .show
= cfq_fifo_expire_sync_show
,
2276 .store
= cfq_fifo_expire_sync_store
,
2278 static struct cfq_fs_entry cfq_fifo_expire_async_entry
= {
2279 .attr
= {.name
= "fifo_expire_async", .mode
= S_IRUGO
| S_IWUSR
},
2280 .show
= cfq_fifo_expire_async_show
,
2281 .store
= cfq_fifo_expire_async_store
,
2283 static struct cfq_fs_entry cfq_back_max_entry
= {
2284 .attr
= {.name
= "back_seek_max", .mode
= S_IRUGO
| S_IWUSR
},
2285 .show
= cfq_back_max_show
,
2286 .store
= cfq_back_max_store
,
2288 static struct cfq_fs_entry cfq_back_penalty_entry
= {
2289 .attr
= {.name
= "back_seek_penalty", .mode
= S_IRUGO
| S_IWUSR
},
2290 .show
= cfq_back_penalty_show
,
2291 .store
= cfq_back_penalty_store
,
2293 static struct cfq_fs_entry cfq_slice_sync_entry
= {
2294 .attr
= {.name
= "slice_sync", .mode
= S_IRUGO
| S_IWUSR
},
2295 .show
= cfq_slice_sync_show
,
2296 .store
= cfq_slice_sync_store
,
2298 static struct cfq_fs_entry cfq_slice_async_entry
= {
2299 .attr
= {.name
= "slice_async", .mode
= S_IRUGO
| S_IWUSR
},
2300 .show
= cfq_slice_async_show
,
2301 .store
= cfq_slice_async_store
,
2303 static struct cfq_fs_entry cfq_slice_async_rq_entry
= {
2304 .attr
= {.name
= "slice_async_rq", .mode
= S_IRUGO
| S_IWUSR
},
2305 .show
= cfq_slice_async_rq_show
,
2306 .store
= cfq_slice_async_rq_store
,
2308 static struct cfq_fs_entry cfq_slice_idle_entry
= {
2309 .attr
= {.name
= "slice_idle", .mode
= S_IRUGO
| S_IWUSR
},
2310 .show
= cfq_slice_idle_show
,
2311 .store
= cfq_slice_idle_store
,
2313 static struct cfq_fs_entry cfq_max_depth_entry
= {
2314 .attr
= {.name
= "max_depth", .mode
= S_IRUGO
| S_IWUSR
},
2315 .show
= cfq_max_depth_show
,
2316 .store
= cfq_max_depth_store
,
2319 static struct attribute
*default_attrs
[] = {
2320 &cfq_quantum_entry
.attr
,
2321 &cfq_queued_entry
.attr
,
2322 &cfq_fifo_expire_sync_entry
.attr
,
2323 &cfq_fifo_expire_async_entry
.attr
,
2324 &cfq_back_max_entry
.attr
,
2325 &cfq_back_penalty_entry
.attr
,
2326 &cfq_slice_sync_entry
.attr
,
2327 &cfq_slice_async_entry
.attr
,
2328 &cfq_slice_async_rq_entry
.attr
,
2329 &cfq_slice_idle_entry
.attr
,
2330 &cfq_max_depth_entry
.attr
,
2334 #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2337 cfq_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
2339 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2340 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2345 return entry
->show(e
->elevator_data
, page
);
2349 cfq_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
2350 const char *page
, size_t length
)
2352 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2353 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2358 return entry
->store(e
->elevator_data
, page
, length
);
2361 static struct sysfs_ops cfq_sysfs_ops
= {
2362 .show
= cfq_attr_show
,
2363 .store
= cfq_attr_store
,
2366 static struct kobj_type cfq_ktype
= {
2367 .sysfs_ops
= &cfq_sysfs_ops
,
2368 .default_attrs
= default_attrs
,
2371 static struct elevator_type iosched_cfq
= {
2373 .elevator_merge_fn
= cfq_merge
,
2374 .elevator_merged_fn
= cfq_merged_request
,
2375 .elevator_merge_req_fn
= cfq_merged_requests
,
2376 .elevator_dispatch_fn
= cfq_dispatch_requests
,
2377 .elevator_add_req_fn
= cfq_insert_request
,
2378 .elevator_activate_req_fn
= cfq_activate_request
,
2379 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
2380 .elevator_queue_empty_fn
= cfq_queue_empty
,
2381 .elevator_completed_req_fn
= cfq_completed_request
,
2382 .elevator_former_req_fn
= cfq_former_request
,
2383 .elevator_latter_req_fn
= cfq_latter_request
,
2384 .elevator_set_req_fn
= cfq_set_request
,
2385 .elevator_put_req_fn
= cfq_put_request
,
2386 .elevator_may_queue_fn
= cfq_may_queue
,
2387 .elevator_init_fn
= cfq_init_queue
,
2388 .elevator_exit_fn
= cfq_exit_queue
,
2390 .elevator_ktype
= &cfq_ktype
,
2391 .elevator_name
= "cfq",
2392 .elevator_owner
= THIS_MODULE
,
2395 static int __init
cfq_init(void)
2400 * could be 0 on HZ < 1000 setups
2402 if (!cfq_slice_async
)
2403 cfq_slice_async
= 1;
2404 if (!cfq_slice_idle
)
2407 if (cfq_slab_setup())
2410 ret
= elv_register(&iosched_cfq
);
2417 static void __exit
cfq_exit(void)
2419 elv_unregister(&iosched_cfq
);
2423 module_init(cfq_init
);
2424 module_exit(cfq_exit
);
2426 MODULE_AUTHOR("Jens Axboe");
2427 MODULE_LICENSE("GPL");
2428 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");