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
= 1;
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 ON_RB(node) ((node)->rb_color != RB_NONE)
88 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
89 #define rq_rb_key(rq) (rq)->sector
91 static kmem_cache_t
*crq_pool
;
92 static kmem_cache_t
*cfq_pool
;
93 static kmem_cache_t
*cfq_ioc_pool
;
95 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
96 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
97 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
98 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
103 #define cfq_cfqq_dispatched(cfqq) \
104 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
106 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
108 #define cfq_cfqq_sync(cfqq) \
109 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
112 * Per block device queue structure
116 request_queue_t
*queue
;
119 * rr list of queues with requests and the count of them
121 struct list_head rr_list
[CFQ_PRIO_LISTS
];
122 struct list_head busy_rr
;
123 struct list_head cur_rr
;
124 struct list_head idle_rr
;
125 unsigned int busy_queues
;
128 * non-ordered list of empty cfqq's
130 struct list_head empty_list
;
135 struct hlist_head
*cfq_hash
;
138 * global crq hash for all queues
140 struct hlist_head
*crq_hash
;
142 unsigned int max_queued
;
149 * schedule slice state info
152 * idle window management
154 struct timer_list idle_slice_timer
;
155 struct work_struct unplug_work
;
157 struct cfq_queue
*active_queue
;
158 struct cfq_io_context
*active_cic
;
159 int cur_prio
, cur_end_prio
;
160 unsigned int dispatch_slice
;
162 struct timer_list idle_class_timer
;
164 sector_t last_sector
;
165 unsigned long last_end_request
;
167 unsigned int rq_starved
;
170 * tunables, see top of file
172 unsigned int cfq_quantum
;
173 unsigned int cfq_queued
;
174 unsigned int cfq_fifo_expire
[2];
175 unsigned int cfq_back_penalty
;
176 unsigned int cfq_back_max
;
177 unsigned int cfq_slice
[2];
178 unsigned int cfq_slice_async_rq
;
179 unsigned int cfq_slice_idle
;
180 unsigned int cfq_max_depth
;
184 * Per process-grouping structure
187 /* reference count */
189 /* parent cfq_data */
190 struct cfq_data
*cfqd
;
191 /* cfqq lookup hash */
192 struct hlist_node cfq_hash
;
195 /* on either rr or empty list of cfqd */
196 struct list_head cfq_list
;
197 /* sorted list of pending requests */
198 struct rb_root sort_list
;
199 /* if fifo isn't expired, next request to serve */
200 struct cfq_rq
*next_crq
;
201 /* requests queued in sort_list */
203 /* currently allocated requests */
205 /* fifo list of requests in sort_list */
206 struct list_head fifo
;
208 unsigned long slice_start
;
209 unsigned long slice_end
;
210 unsigned long slice_left
;
211 unsigned long service_last
;
213 /* number of requests that are on the dispatch list */
216 /* io prio of this group */
217 unsigned short ioprio
, org_ioprio
;
218 unsigned short ioprio_class
, org_ioprio_class
;
220 /* various state flags, see below */
225 struct rb_node rb_node
;
227 struct request
*request
;
228 struct hlist_node hash
;
230 struct cfq_queue
*cfq_queue
;
231 struct cfq_io_context
*io_context
;
233 unsigned int crq_flags
;
236 enum cfqq_state_flags
{
237 CFQ_CFQQ_FLAG_on_rr
= 0,
238 CFQ_CFQQ_FLAG_wait_request
,
239 CFQ_CFQQ_FLAG_must_alloc
,
240 CFQ_CFQQ_FLAG_must_alloc_slice
,
241 CFQ_CFQQ_FLAG_must_dispatch
,
242 CFQ_CFQQ_FLAG_fifo_expire
,
243 CFQ_CFQQ_FLAG_idle_window
,
244 CFQ_CFQQ_FLAG_prio_changed
,
245 CFQ_CFQQ_FLAG_expired
,
248 #define CFQ_CFQQ_FNS(name) \
249 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
251 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
253 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
255 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
257 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
259 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
263 CFQ_CFQQ_FNS(wait_request
);
264 CFQ_CFQQ_FNS(must_alloc
);
265 CFQ_CFQQ_FNS(must_alloc_slice
);
266 CFQ_CFQQ_FNS(must_dispatch
);
267 CFQ_CFQQ_FNS(fifo_expire
);
268 CFQ_CFQQ_FNS(idle_window
);
269 CFQ_CFQQ_FNS(prio_changed
);
270 CFQ_CFQQ_FNS(expired
);
273 enum cfq_rq_state_flags
{
274 CFQ_CRQ_FLAG_in_flight
= 0,
275 CFQ_CRQ_FLAG_in_driver
,
276 CFQ_CRQ_FLAG_is_sync
,
277 CFQ_CRQ_FLAG_requeued
,
280 #define CFQ_CRQ_FNS(name) \
281 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
283 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
285 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
287 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
289 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
291 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
294 CFQ_CRQ_FNS(in_flight
);
295 CFQ_CRQ_FNS(in_driver
);
296 CFQ_CRQ_FNS(is_sync
);
297 CFQ_CRQ_FNS(requeued
);
300 static struct cfq_queue
*cfq_find_cfq_hash(struct cfq_data
*, unsigned int, unsigned short);
301 static void cfq_dispatch_sort(request_queue_t
*, struct cfq_rq
*);
302 static void cfq_put_cfqd(struct cfq_data
*cfqd
);
304 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
307 * lots of deadline iosched dupes, can be abstracted later...
309 static inline void cfq_del_crq_hash(struct cfq_rq
*crq
)
311 hlist_del_init(&crq
->hash
);
314 static void cfq_remove_merge_hints(request_queue_t
*q
, struct cfq_rq
*crq
)
316 cfq_del_crq_hash(crq
);
318 if (q
->last_merge
== crq
->request
)
319 q
->last_merge
= NULL
;
322 static inline void cfq_add_crq_hash(struct cfq_data
*cfqd
, struct cfq_rq
*crq
)
324 const int hash_idx
= CFQ_MHASH_FN(rq_hash_key(crq
->request
));
326 hlist_add_head(&crq
->hash
, &cfqd
->crq_hash
[hash_idx
]);
329 static struct request
*cfq_find_rq_hash(struct cfq_data
*cfqd
, sector_t offset
)
331 struct hlist_head
*hash_list
= &cfqd
->crq_hash
[CFQ_MHASH_FN(offset
)];
332 struct hlist_node
*entry
, *next
;
334 hlist_for_each_safe(entry
, next
, hash_list
) {
335 struct cfq_rq
*crq
= list_entry_hash(entry
);
336 struct request
*__rq
= crq
->request
;
338 if (!rq_mergeable(__rq
)) {
339 cfq_del_crq_hash(crq
);
343 if (rq_hash_key(__rq
) == offset
)
350 static inline int cfq_pending_requests(struct cfq_data
*cfqd
)
352 return !list_empty(&cfqd
->queue
->queue_head
) || cfqd
->busy_queues
;
356 * scheduler run of queue, if there are requests pending and no one in the
357 * driver that will restart queueing
359 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
361 if (!cfqd
->rq_in_driver
&& cfq_pending_requests(cfqd
))
362 kblockd_schedule_work(&cfqd
->unplug_work
);
365 static int cfq_queue_empty(request_queue_t
*q
)
367 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
369 return !cfq_pending_requests(cfqd
);
373 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
374 * We choose the request that is closest to the head right now. Distance
375 * behind the head are penalized and only allowed to a certain extent.
377 static struct cfq_rq
*
378 cfq_choose_req(struct cfq_data
*cfqd
, struct cfq_rq
*crq1
, struct cfq_rq
*crq2
)
380 sector_t last
, s1
, s2
, d1
= 0, d2
= 0;
381 int r1_wrap
= 0, r2_wrap
= 0; /* requests are behind the disk head */
382 unsigned long back_max
;
384 if (crq1
== NULL
|| crq1
== crq2
)
388 if (cfq_crq_requeued(crq1
))
390 if (cfq_crq_requeued(crq2
))
393 s1
= crq1
->request
->sector
;
394 s2
= crq2
->request
->sector
;
396 last
= cfqd
->last_sector
;
399 * by definition, 1KiB is 2 sectors
401 back_max
= cfqd
->cfq_back_max
* 2;
404 * Strict one way elevator _except_ in the case where we allow
405 * short backward seeks which are biased as twice the cost of a
406 * similar forward seek.
410 else if (s1
+ back_max
>= last
)
411 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
417 else if (s2
+ back_max
>= last
)
418 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
422 /* Found required data */
423 if (!r1_wrap
&& r2_wrap
)
425 else if (!r2_wrap
&& r1_wrap
)
427 else if (r1_wrap
&& r2_wrap
) {
428 /* both behind the head */
435 /* Both requests in front of the head */
449 * would be nice to take fifo expire time into account as well
451 static struct cfq_rq
*
452 cfq_find_next_crq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
455 struct cfq_rq
*crq_next
= NULL
, *crq_prev
= NULL
;
456 struct rb_node
*rbnext
, *rbprev
;
459 if (ON_RB(&last
->rb_node
))
460 rbnext
= rb_next(&last
->rb_node
);
462 rbnext
= rb_first(&cfqq
->sort_list
);
463 if (rbnext
== &last
->rb_node
)
467 rbprev
= rb_prev(&last
->rb_node
);
470 crq_prev
= rb_entry_crq(rbprev
);
472 crq_next
= rb_entry_crq(rbnext
);
474 return cfq_choose_req(cfqd
, crq_next
, crq_prev
);
477 static void cfq_update_next_crq(struct cfq_rq
*crq
)
479 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
481 if (cfqq
->next_crq
== crq
)
482 cfqq
->next_crq
= cfq_find_next_crq(cfqq
->cfqd
, cfqq
, crq
);
485 static void cfq_resort_rr_list(struct cfq_queue
*cfqq
, int preempted
)
487 struct cfq_data
*cfqd
= cfqq
->cfqd
;
488 struct list_head
*list
, *entry
;
490 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
492 list_del(&cfqq
->cfq_list
);
494 if (cfq_class_rt(cfqq
))
495 list
= &cfqd
->cur_rr
;
496 else if (cfq_class_idle(cfqq
))
497 list
= &cfqd
->idle_rr
;
500 * if cfqq has requests in flight, don't allow it to be
501 * found in cfq_set_active_queue before it has finished them.
502 * this is done to increase fairness between a process that
503 * has lots of io pending vs one that only generates one
504 * sporadically or synchronously
506 if (cfq_cfqq_dispatched(cfqq
))
507 list
= &cfqd
->busy_rr
;
509 list
= &cfqd
->rr_list
[cfqq
->ioprio
];
513 * if queue was preempted, just add to front to be fair. busy_rr
516 if (preempted
|| list
== &cfqd
->busy_rr
) {
517 list_add(&cfqq
->cfq_list
, list
);
522 * sort by when queue was last serviced
525 while ((entry
= entry
->prev
) != list
) {
526 struct cfq_queue
*__cfqq
= list_entry_cfqq(entry
);
528 if (!__cfqq
->service_last
)
530 if (time_before(__cfqq
->service_last
, cfqq
->service_last
))
534 list_add(&cfqq
->cfq_list
, entry
);
538 * add to busy list of queues for service, trying to be fair in ordering
539 * the pending list according to last request service
542 cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
, int requeue
)
544 BUG_ON(cfq_cfqq_on_rr(cfqq
));
545 cfq_mark_cfqq_on_rr(cfqq
);
548 cfq_resort_rr_list(cfqq
, requeue
);
552 cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
554 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
555 cfq_clear_cfqq_on_rr(cfqq
);
556 list_move(&cfqq
->cfq_list
, &cfqd
->empty_list
);
558 BUG_ON(!cfqd
->busy_queues
);
563 * rb tree support functions
565 static inline void cfq_del_crq_rb(struct cfq_rq
*crq
)
567 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
569 if (ON_RB(&crq
->rb_node
)) {
570 struct cfq_data
*cfqd
= cfqq
->cfqd
;
571 const int sync
= cfq_crq_is_sync(crq
);
573 BUG_ON(!cfqq
->queued
[sync
]);
574 cfqq
->queued
[sync
]--;
576 cfq_update_next_crq(crq
);
578 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
579 RB_CLEAR_COLOR(&crq
->rb_node
);
581 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY(&cfqq
->sort_list
))
582 cfq_del_cfqq_rr(cfqd
, cfqq
);
586 static struct cfq_rq
*
587 __cfq_add_crq_rb(struct cfq_rq
*crq
)
589 struct rb_node
**p
= &crq
->cfq_queue
->sort_list
.rb_node
;
590 struct rb_node
*parent
= NULL
;
591 struct cfq_rq
*__crq
;
595 __crq
= rb_entry_crq(parent
);
597 if (crq
->rb_key
< __crq
->rb_key
)
599 else if (crq
->rb_key
> __crq
->rb_key
)
605 rb_link_node(&crq
->rb_node
, parent
, p
);
609 static void cfq_add_crq_rb(struct cfq_rq
*crq
)
611 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
612 struct cfq_data
*cfqd
= cfqq
->cfqd
;
613 struct request
*rq
= crq
->request
;
614 struct cfq_rq
*__alias
;
616 crq
->rb_key
= rq_rb_key(rq
);
617 cfqq
->queued
[cfq_crq_is_sync(crq
)]++;
620 * looks a little odd, but the first insert might return an alias.
621 * if that happens, put the alias on the dispatch list
623 while ((__alias
= __cfq_add_crq_rb(crq
)) != NULL
)
624 cfq_dispatch_sort(cfqd
->queue
, __alias
);
626 rb_insert_color(&crq
->rb_node
, &cfqq
->sort_list
);
628 if (!cfq_cfqq_on_rr(cfqq
))
629 cfq_add_cfqq_rr(cfqd
, cfqq
, cfq_crq_requeued(crq
));
632 * check if this request is a better next-serve candidate
634 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
638 cfq_reposition_crq_rb(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
640 if (ON_RB(&crq
->rb_node
)) {
641 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
642 cfqq
->queued
[cfq_crq_is_sync(crq
)]--;
648 static struct request
*cfq_find_rq_rb(struct cfq_data
*cfqd
, sector_t sector
)
651 struct cfq_queue
*cfqq
= cfq_find_cfq_hash(cfqd
, current
->pid
, CFQ_KEY_ANY
);
657 n
= cfqq
->sort_list
.rb_node
;
659 struct cfq_rq
*crq
= rb_entry_crq(n
);
661 if (sector
< crq
->rb_key
)
663 else if (sector
> crq
->rb_key
)
673 static void cfq_deactivate_request(request_queue_t
*q
, struct request
*rq
)
675 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
676 struct cfq_rq
*crq
= RQ_DATA(rq
);
679 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
681 if (cfq_crq_in_driver(crq
)) {
682 cfq_clear_crq_in_driver(crq
);
683 WARN_ON(!cfqd
->rq_in_driver
);
684 cfqd
->rq_in_driver
--;
686 if (cfq_crq_in_flight(crq
)) {
687 const int sync
= cfq_crq_is_sync(crq
);
689 cfq_clear_crq_in_flight(crq
);
690 WARN_ON(!cfqq
->on_dispatch
[sync
]);
691 cfqq
->on_dispatch
[sync
]--;
693 cfq_mark_crq_requeued(crq
);
698 * make sure the service time gets corrected on reissue of this request
700 static void cfq_requeue_request(request_queue_t
*q
, struct request
*rq
)
702 cfq_deactivate_request(q
, rq
);
703 list_add(&rq
->queuelist
, &q
->queue_head
);
706 static void cfq_remove_request(request_queue_t
*q
, struct request
*rq
)
708 struct cfq_rq
*crq
= RQ_DATA(rq
);
711 list_del_init(&rq
->queuelist
);
713 cfq_remove_merge_hints(q
, crq
);
719 cfq_merge(request_queue_t
*q
, struct request
**req
, struct bio
*bio
)
721 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
722 struct request
*__rq
;
725 ret
= elv_try_last_merge(q
, bio
);
726 if (ret
!= ELEVATOR_NO_MERGE
) {
727 __rq
= q
->last_merge
;
731 __rq
= cfq_find_rq_hash(cfqd
, bio
->bi_sector
);
732 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
733 ret
= ELEVATOR_BACK_MERGE
;
737 __rq
= cfq_find_rq_rb(cfqd
, bio
->bi_sector
+ bio_sectors(bio
));
738 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
739 ret
= ELEVATOR_FRONT_MERGE
;
743 return ELEVATOR_NO_MERGE
;
745 q
->last_merge
= __rq
;
751 static void cfq_merged_request(request_queue_t
*q
, struct request
*req
)
753 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
754 struct cfq_rq
*crq
= RQ_DATA(req
);
756 cfq_del_crq_hash(crq
);
757 cfq_add_crq_hash(cfqd
, crq
);
759 if (ON_RB(&crq
->rb_node
) && (rq_rb_key(req
) != crq
->rb_key
)) {
760 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
762 cfq_update_next_crq(crq
);
763 cfq_reposition_crq_rb(cfqq
, crq
);
770 cfq_merged_requests(request_queue_t
*q
, struct request
*rq
,
771 struct request
*next
)
773 cfq_merged_request(q
, rq
);
776 * reposition in fifo if next is older than rq
778 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
779 time_before(next
->start_time
, rq
->start_time
))
780 list_move(&rq
->queuelist
, &next
->queuelist
);
782 cfq_remove_request(q
, next
);
786 __cfq_set_active_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
790 * stop potential idle class queues waiting service
792 del_timer(&cfqd
->idle_class_timer
);
794 cfqq
->slice_start
= jiffies
;
796 cfqq
->slice_left
= 0;
797 cfq_clear_cfqq_must_alloc_slice(cfqq
);
798 cfq_clear_cfqq_fifo_expire(cfqq
);
799 cfq_clear_cfqq_expired(cfqq
);
802 cfqd
->active_queue
= cfqq
;
815 static int cfq_get_next_prio_level(struct cfq_data
*cfqd
)
824 for (p
= cfqd
->cur_prio
; p
<= cfqd
->cur_end_prio
; p
++) {
825 if (!list_empty(&cfqd
->rr_list
[p
])) {
834 if (++cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
835 cfqd
->cur_end_prio
= 0;
842 if (unlikely(prio
== -1))
845 BUG_ON(prio
>= CFQ_PRIO_LISTS
);
847 list_splice_init(&cfqd
->rr_list
[prio
], &cfqd
->cur_rr
);
849 cfqd
->cur_prio
= prio
+ 1;
850 if (cfqd
->cur_prio
> cfqd
->cur_end_prio
) {
851 cfqd
->cur_end_prio
= cfqd
->cur_prio
;
854 if (cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
856 cfqd
->cur_end_prio
= 0;
862 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
)
864 struct cfq_queue
*cfqq
;
867 * if current queue is expired but not done with its requests yet,
868 * wait for that to happen
870 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
871 if (cfq_cfqq_expired(cfqq
) && cfq_cfqq_dispatched(cfqq
))
876 * if current list is non-empty, grab first entry. if it is empty,
877 * get next prio level and grab first entry then if any are spliced
879 if (!list_empty(&cfqd
->cur_rr
) || cfq_get_next_prio_level(cfqd
) != -1)
880 cfqq
= list_entry_cfqq(cfqd
->cur_rr
.next
);
883 * if we have idle queues and no rt or be queues had pending
884 * requests, either allow immediate service if the grace period
885 * has passed or arm the idle grace timer
887 if (!cfqq
&& !list_empty(&cfqd
->idle_rr
)) {
888 unsigned long end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
890 if (time_after_eq(jiffies
, end
))
891 cfqq
= list_entry_cfqq(cfqd
->idle_rr
.next
);
893 mod_timer(&cfqd
->idle_class_timer
, end
);
896 __cfq_set_active_queue(cfqd
, cfqq
);
901 * current cfqq expired its slice (or was too idle), select new one
904 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
907 unsigned long now
= jiffies
;
909 if (cfq_cfqq_wait_request(cfqq
))
910 del_timer(&cfqd
->idle_slice_timer
);
912 if (!preempted
&& !cfq_cfqq_dispatched(cfqq
))
913 cfqq
->service_last
= now
;
915 cfq_clear_cfqq_must_dispatch(cfqq
);
916 cfq_clear_cfqq_wait_request(cfqq
);
919 * store what was left of this slice, if the queue idled out
922 if (time_after(now
, cfqq
->slice_end
))
923 cfqq
->slice_left
= now
- cfqq
->slice_end
;
925 cfqq
->slice_left
= 0;
927 if (cfq_cfqq_on_rr(cfqq
))
928 cfq_resort_rr_list(cfqq
, preempted
);
930 if (cfqq
== cfqd
->active_queue
)
931 cfqd
->active_queue
= NULL
;
933 if (cfqd
->active_cic
) {
934 put_io_context(cfqd
->active_cic
->ioc
);
935 cfqd
->active_cic
= NULL
;
938 cfqd
->dispatch_slice
= 0;
941 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, int preempted
)
943 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
947 * use deferred expiry, if there are requests in progress as
948 * not to disturb the slice of the next queue
950 if (cfq_cfqq_dispatched(cfqq
))
951 cfq_mark_cfqq_expired(cfqq
);
953 __cfq_slice_expired(cfqd
, cfqq
, preempted
);
957 static int cfq_arm_slice_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
960 WARN_ON(!RB_EMPTY(&cfqq
->sort_list
));
961 WARN_ON(cfqq
!= cfqd
->active_queue
);
964 * idle is disabled, either manually or by past process history
966 if (!cfqd
->cfq_slice_idle
)
968 if (!cfq_cfqq_idle_window(cfqq
))
971 * task has exited, don't wait
973 if (cfqd
->active_cic
&& !cfqd
->active_cic
->ioc
->task
)
976 cfq_mark_cfqq_must_dispatch(cfqq
);
977 cfq_mark_cfqq_wait_request(cfqq
);
979 if (!timer_pending(&cfqd
->idle_slice_timer
)) {
980 unsigned long slice_left
= min(cfqq
->slice_end
- 1, (unsigned long) cfqd
->cfq_slice_idle
);
982 cfqd
->idle_slice_timer
.expires
= jiffies
+ slice_left
;
983 add_timer(&cfqd
->idle_slice_timer
);
990 * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues,
991 * this function sector sorts the selected request to minimize seeks. we start
992 * at cfqd->last_sector, not 0.
994 static void cfq_dispatch_sort(request_queue_t
*q
, struct cfq_rq
*crq
)
996 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
997 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
998 struct list_head
*head
= &q
->queue_head
, *entry
= head
;
999 struct request
*__rq
;
1002 list_del(&crq
->request
->queuelist
);
1004 last
= cfqd
->last_sector
;
1005 list_for_each_entry_reverse(__rq
, head
, queuelist
) {
1006 struct cfq_rq
*__crq
= RQ_DATA(__rq
);
1008 if (blk_barrier_rq(__rq
))
1010 if (!blk_fs_request(__rq
))
1012 if (cfq_crq_requeued(__crq
))
1015 if (__rq
->sector
<= crq
->request
->sector
)
1017 if (__rq
->sector
> last
&& crq
->request
->sector
< last
) {
1018 last
= crq
->request
->sector
+ crq
->request
->nr_sectors
;
1021 entry
= &__rq
->queuelist
;
1024 cfqd
->last_sector
= last
;
1026 cfqq
->next_crq
= cfq_find_next_crq(cfqd
, cfqq
, crq
);
1028 cfq_del_crq_rb(crq
);
1029 cfq_remove_merge_hints(q
, crq
);
1031 cfq_mark_crq_in_flight(crq
);
1032 cfq_clear_crq_requeued(crq
);
1034 cfqq
->on_dispatch
[cfq_crq_is_sync(crq
)]++;
1035 list_add_tail(&crq
->request
->queuelist
, entry
);
1039 * return expired entry, or NULL to just start from scratch in rbtree
1041 static inline struct cfq_rq
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1043 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1047 if (cfq_cfqq_fifo_expire(cfqq
))
1050 if (!list_empty(&cfqq
->fifo
)) {
1051 int fifo
= cfq_cfqq_class_sync(cfqq
);
1053 crq
= RQ_DATA(list_entry_fifo(cfqq
->fifo
.next
));
1055 if (time_after(jiffies
, rq
->start_time
+ cfqd
->cfq_fifo_expire
[fifo
])) {
1056 cfq_mark_cfqq_fifo_expire(cfqq
);
1065 * Scale schedule slice based on io priority. Use the sync time slice only
1066 * if a queue is marked sync and has sync io queued. A sync queue with async
1067 * io only, should not get full sync slice length.
1070 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1072 const int base_slice
= cfqd
->cfq_slice
[cfq_cfqq_sync(cfqq
)];
1074 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1076 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - cfqq
->ioprio
));
1080 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1082 cfqq
->slice_end
= cfq_prio_to_slice(cfqd
, cfqq
) + jiffies
;
1086 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1088 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1090 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1092 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1096 * get next queue for service
1098 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
, int force
)
1100 unsigned long now
= jiffies
;
1101 struct cfq_queue
*cfqq
;
1103 cfqq
= cfqd
->active_queue
;
1107 if (cfq_cfqq_expired(cfqq
))
1113 if (!cfq_cfqq_must_dispatch(cfqq
) && time_after(now
, cfqq
->slice_end
))
1117 * if queue has requests, dispatch one. if not, check if
1118 * enough slice is left to wait for one
1120 if (!RB_EMPTY(&cfqq
->sort_list
))
1122 else if (!force
&& cfq_cfqq_class_sync(cfqq
) &&
1123 time_before(now
, cfqq
->slice_end
)) {
1124 if (cfq_arm_slice_timer(cfqd
, cfqq
))
1129 cfq_slice_expired(cfqd
, 0);
1131 cfqq
= cfq_set_active_queue(cfqd
);
1137 __cfq_dispatch_requests(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1142 BUG_ON(RB_EMPTY(&cfqq
->sort_list
));
1148 * follow expired path, else get first next available
1150 if ((crq
= cfq_check_fifo(cfqq
)) == NULL
)
1151 crq
= cfqq
->next_crq
;
1154 * finally, insert request into driver dispatch list
1156 cfq_dispatch_sort(cfqd
->queue
, crq
);
1158 cfqd
->dispatch_slice
++;
1161 if (!cfqd
->active_cic
) {
1162 atomic_inc(&crq
->io_context
->ioc
->refcount
);
1163 cfqd
->active_cic
= crq
->io_context
;
1166 if (RB_EMPTY(&cfqq
->sort_list
))
1169 } while (dispatched
< max_dispatch
);
1172 * if slice end isn't set yet, set it. if at least one request was
1173 * sync, use the sync time slice value
1175 if (!cfqq
->slice_end
)
1176 cfq_set_prio_slice(cfqd
, cfqq
);
1179 * expire an async queue immediately if it has used up its slice. idle
1180 * queue always expire after 1 dispatch round.
1182 if ((!cfq_cfqq_sync(cfqq
) &&
1183 cfqd
->dispatch_slice
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1184 cfq_class_idle(cfqq
))
1185 cfq_slice_expired(cfqd
, 0);
1191 cfq_dispatch_requests(request_queue_t
*q
, int max_dispatch
, int force
)
1193 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1194 struct cfq_queue
*cfqq
;
1196 if (!cfqd
->busy_queues
)
1199 cfqq
= cfq_select_queue(cfqd
, force
);
1201 cfq_clear_cfqq_must_dispatch(cfqq
);
1202 cfq_clear_cfqq_wait_request(cfqq
);
1203 del_timer(&cfqd
->idle_slice_timer
);
1205 if (cfq_class_idle(cfqq
))
1208 return __cfq_dispatch_requests(cfqd
, cfqq
, max_dispatch
);
1214 static inline void cfq_account_dispatch(struct cfq_rq
*crq
)
1216 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1217 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1219 if (unlikely(!blk_fs_request(crq
->request
)))
1223 * accounted bit is necessary since some drivers will call
1224 * elv_next_request() many times for the same request (eg ide)
1226 if (cfq_crq_in_driver(crq
))
1229 cfq_mark_crq_in_driver(crq
);
1230 cfqd
->rq_in_driver
++;
1234 cfq_account_completion(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
1236 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1239 if (!cfq_crq_in_driver(crq
))
1244 WARN_ON(!cfqd
->rq_in_driver
);
1245 cfqd
->rq_in_driver
--;
1247 if (!cfq_class_idle(cfqq
))
1248 cfqd
->last_end_request
= now
;
1250 if (!cfq_cfqq_dispatched(cfqq
)) {
1251 if (cfq_cfqq_on_rr(cfqq
)) {
1252 cfqq
->service_last
= now
;
1253 cfq_resort_rr_list(cfqq
, 0);
1255 if (cfq_cfqq_expired(cfqq
)) {
1256 __cfq_slice_expired(cfqd
, cfqq
, 0);
1257 cfq_schedule_dispatch(cfqd
);
1261 if (cfq_crq_is_sync(crq
))
1262 crq
->io_context
->last_end_request
= now
;
1265 static struct request
*cfq_next_request(request_queue_t
*q
)
1267 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1270 if (!list_empty(&q
->queue_head
)) {
1273 rq
= list_entry_rq(q
->queue_head
.next
);
1277 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1280 * if idle window is disabled, allow queue buildup
1282 if (!cfq_crq_in_driver(crq
) &&
1283 !cfq_cfqq_idle_window(cfqq
) &&
1284 !blk_barrier_rq(rq
) &&
1285 cfqd
->rq_in_driver
>= cfqd
->cfq_max_depth
)
1288 cfq_remove_merge_hints(q
, crq
);
1289 cfq_account_dispatch(crq
);
1295 if (cfq_dispatch_requests(q
, cfqd
->cfq_quantum
, 0))
1302 * task holds one reference to the queue, dropped when task exits. each crq
1303 * in-flight on this queue also holds a reference, dropped when crq is freed.
1305 * queue lock must be held here.
1307 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1309 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1311 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1313 if (!atomic_dec_and_test(&cfqq
->ref
))
1316 BUG_ON(rb_first(&cfqq
->sort_list
));
1317 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1318 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1320 if (unlikely(cfqd
->active_queue
== cfqq
)) {
1321 __cfq_slice_expired(cfqd
, cfqq
, 0);
1322 cfq_schedule_dispatch(cfqd
);
1325 cfq_put_cfqd(cfqq
->cfqd
);
1328 * it's on the empty list and still hashed
1330 list_del(&cfqq
->cfq_list
);
1331 hlist_del(&cfqq
->cfq_hash
);
1332 kmem_cache_free(cfq_pool
, cfqq
);
1335 static inline struct cfq_queue
*
1336 __cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned int prio
,
1339 struct hlist_head
*hash_list
= &cfqd
->cfq_hash
[hashval
];
1340 struct hlist_node
*entry
, *next
;
1342 hlist_for_each_safe(entry
, next
, hash_list
) {
1343 struct cfq_queue
*__cfqq
= list_entry_qhash(entry
);
1344 const unsigned short __p
= IOPRIO_PRIO_VALUE(__cfqq
->ioprio_class
, __cfqq
->ioprio
);
1346 if (__cfqq
->key
== key
&& (__p
== prio
|| prio
== CFQ_KEY_ANY
))
1353 static struct cfq_queue
*
1354 cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned short prio
)
1356 return __cfq_find_cfq_hash(cfqd
, key
, prio
, hash_long(key
, CFQ_QHASH_SHIFT
));
1359 static void cfq_free_io_context(struct cfq_io_context
*cic
)
1361 struct cfq_io_context
*__cic
;
1362 struct list_head
*entry
, *next
;
1364 list_for_each_safe(entry
, next
, &cic
->list
) {
1365 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1366 kmem_cache_free(cfq_ioc_pool
, __cic
);
1369 kmem_cache_free(cfq_ioc_pool
, cic
);
1373 * Called with interrupts disabled
1375 static void cfq_exit_single_io_context(struct cfq_io_context
*cic
)
1377 struct cfq_data
*cfqd
= cic
->cfqq
->cfqd
;
1378 request_queue_t
*q
= cfqd
->queue
;
1380 WARN_ON(!irqs_disabled());
1382 spin_lock(q
->queue_lock
);
1384 if (unlikely(cic
->cfqq
== cfqd
->active_queue
)) {
1385 __cfq_slice_expired(cfqd
, cic
->cfqq
, 0);
1386 cfq_schedule_dispatch(cfqd
);
1389 cfq_put_queue(cic
->cfqq
);
1391 spin_unlock(q
->queue_lock
);
1395 * Another task may update the task cic list, if it is doing a queue lookup
1396 * on its behalf. cfq_cic_lock excludes such concurrent updates
1398 static void cfq_exit_io_context(struct cfq_io_context
*cic
)
1400 struct cfq_io_context
*__cic
;
1401 struct list_head
*entry
;
1402 unsigned long flags
;
1404 local_irq_save(flags
);
1407 * put the reference this task is holding to the various queues
1409 list_for_each(entry
, &cic
->list
) {
1410 __cic
= list_entry(entry
, struct cfq_io_context
, list
);
1411 cfq_exit_single_io_context(__cic
);
1414 cfq_exit_single_io_context(cic
);
1415 local_irq_restore(flags
);
1418 static struct cfq_io_context
*
1419 cfq_alloc_io_context(struct cfq_data
*cfqd
, int gfp_mask
)
1421 struct cfq_io_context
*cic
= kmem_cache_alloc(cfq_ioc_pool
, gfp_mask
);
1424 INIT_LIST_HEAD(&cic
->list
);
1427 cic
->last_end_request
= jiffies
;
1428 cic
->ttime_total
= 0;
1429 cic
->ttime_samples
= 0;
1430 cic
->ttime_mean
= 0;
1431 cic
->dtor
= cfq_free_io_context
;
1432 cic
->exit
= cfq_exit_io_context
;
1438 static void cfq_init_prio_data(struct cfq_queue
*cfqq
)
1440 struct task_struct
*tsk
= current
;
1443 if (!cfq_cfqq_prio_changed(cfqq
))
1446 ioprio_class
= IOPRIO_PRIO_CLASS(tsk
->ioprio
);
1447 switch (ioprio_class
) {
1449 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1450 case IOPRIO_CLASS_NONE
:
1452 * no prio set, place us in the middle of the BE classes
1454 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1455 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1457 case IOPRIO_CLASS_RT
:
1458 cfqq
->ioprio
= task_ioprio(tsk
);
1459 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1461 case IOPRIO_CLASS_BE
:
1462 cfqq
->ioprio
= task_ioprio(tsk
);
1463 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1465 case IOPRIO_CLASS_IDLE
:
1466 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
1468 cfq_clear_cfqq_idle_window(cfqq
);
1473 * keep track of original prio settings in case we have to temporarily
1474 * elevate the priority of this queue
1476 cfqq
->org_ioprio
= cfqq
->ioprio
;
1477 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
1479 if (cfq_cfqq_on_rr(cfqq
))
1480 cfq_resort_rr_list(cfqq
, 0);
1482 cfq_clear_cfqq_prio_changed(cfqq
);
1485 static inline void changed_ioprio(struct cfq_queue
*cfqq
)
1488 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1490 spin_lock(cfqd
->queue
->queue_lock
);
1491 cfq_mark_cfqq_prio_changed(cfqq
);
1492 cfq_init_prio_data(cfqq
);
1493 spin_unlock(cfqd
->queue
->queue_lock
);
1498 * callback from sys_ioprio_set, irqs are disabled
1500 static int cfq_ioc_set_ioprio(struct io_context
*ioc
, unsigned int ioprio
)
1502 struct cfq_io_context
*cic
= ioc
->cic
;
1504 changed_ioprio(cic
->cfqq
);
1506 list_for_each_entry(cic
, &cic
->list
, list
)
1507 changed_ioprio(cic
->cfqq
);
1512 static struct cfq_queue
*
1513 cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, unsigned short ioprio
,
1516 const int hashval
= hash_long(key
, CFQ_QHASH_SHIFT
);
1517 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1520 cfqq
= __cfq_find_cfq_hash(cfqd
, key
, ioprio
, hashval
);
1526 } else if (gfp_mask
& __GFP_WAIT
) {
1527 spin_unlock_irq(cfqd
->queue
->queue_lock
);
1528 new_cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1529 spin_lock_irq(cfqd
->queue
->queue_lock
);
1532 cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1537 memset(cfqq
, 0, sizeof(*cfqq
));
1539 INIT_HLIST_NODE(&cfqq
->cfq_hash
);
1540 INIT_LIST_HEAD(&cfqq
->cfq_list
);
1541 RB_CLEAR_ROOT(&cfqq
->sort_list
);
1542 INIT_LIST_HEAD(&cfqq
->fifo
);
1545 hlist_add_head(&cfqq
->cfq_hash
, &cfqd
->cfq_hash
[hashval
]);
1546 atomic_set(&cfqq
->ref
, 0);
1548 atomic_inc(&cfqd
->ref
);
1549 cfqq
->service_last
= 0;
1551 * set ->slice_left to allow preemption for a new process
1553 cfqq
->slice_left
= 2 * cfqd
->cfq_slice_idle
;
1554 cfq_mark_cfqq_idle_window(cfqq
);
1555 cfq_mark_cfqq_prio_changed(cfqq
);
1556 cfq_init_prio_data(cfqq
);
1560 kmem_cache_free(cfq_pool
, new_cfqq
);
1562 atomic_inc(&cfqq
->ref
);
1564 WARN_ON((gfp_mask
& __GFP_WAIT
) && !cfqq
);
1569 * Setup general io context and cfq io context. There can be several cfq
1570 * io contexts per general io context, if this process is doing io to more
1571 * than one device managed by cfq. Note that caller is holding a reference to
1572 * cfqq, so we don't need to worry about it disappearing
1574 static struct cfq_io_context
*
1575 cfq_get_io_context(struct cfq_data
*cfqd
, pid_t pid
, int gfp_mask
)
1577 struct io_context
*ioc
= NULL
;
1578 struct cfq_io_context
*cic
;
1580 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1582 ioc
= get_io_context(gfp_mask
);
1586 if ((cic
= ioc
->cic
) == NULL
) {
1587 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1593 * manually increment generic io_context usage count, it
1594 * cannot go away since we are already holding one ref to it
1597 ioc
->set_ioprio
= cfq_ioc_set_ioprio
;
1600 atomic_inc(&cfqd
->ref
);
1602 struct cfq_io_context
*__cic
;
1605 * the first cic on the list is actually the head itself
1607 if (cic
->key
== cfqd
)
1611 * cic exists, check if we already are there. linear search
1612 * should be ok here, the list will usually not be more than
1613 * 1 or a few entries long
1615 list_for_each_entry(__cic
, &cic
->list
, list
) {
1617 * this process is already holding a reference to
1618 * this queue, so no need to get one more
1620 if (__cic
->key
== cfqd
) {
1627 * nope, process doesn't have a cic assoicated with this
1628 * cfqq yet. get a new one and add to list
1630 __cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1636 atomic_inc(&cfqd
->ref
);
1637 list_add(&__cic
->list
, &cic
->list
);
1644 put_io_context(ioc
);
1649 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
1651 unsigned long elapsed
, ttime
;
1654 * if this context already has stuff queued, thinktime is from
1655 * last queue not last end
1658 if (time_after(cic
->last_end_request
, cic
->last_queue
))
1659 elapsed
= jiffies
- cic
->last_end_request
;
1661 elapsed
= jiffies
- cic
->last_queue
;
1663 elapsed
= jiffies
- cic
->last_end_request
;
1666 ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
1668 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
1669 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
1670 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
1673 #define sample_valid(samples) ((samples) > 80)
1676 * Disable idle window if the process thinks too long or seeks so much that
1680 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1681 struct cfq_io_context
*cic
)
1683 int enable_idle
= cfq_cfqq_idle_window(cfqq
);
1685 if (!cic
->ioc
->task
|| !cfqd
->cfq_slice_idle
)
1687 else if (sample_valid(cic
->ttime_samples
)) {
1688 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
1695 cfq_mark_cfqq_idle_window(cfqq
);
1697 cfq_clear_cfqq_idle_window(cfqq
);
1702 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1703 * no or if we aren't sure, a 1 will cause a preempt.
1706 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
1709 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1711 if (cfq_class_idle(new_cfqq
))
1717 if (cfq_class_idle(cfqq
))
1719 if (!cfq_cfqq_wait_request(new_cfqq
))
1722 * if it doesn't have slice left, forget it
1724 if (new_cfqq
->slice_left
< cfqd
->cfq_slice_idle
)
1726 if (cfq_crq_is_sync(crq
) && !cfq_cfqq_sync(cfqq
))
1733 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1734 * let it have half of its nominal slice.
1736 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1738 struct cfq_queue
*__cfqq
, *next
;
1740 list_for_each_entry_safe(__cfqq
, next
, &cfqd
->cur_rr
, cfq_list
)
1741 cfq_resort_rr_list(__cfqq
, 1);
1743 if (!cfqq
->slice_left
)
1744 cfqq
->slice_left
= cfq_prio_to_slice(cfqd
, cfqq
) / 2;
1746 cfqq
->slice_end
= cfqq
->slice_left
+ jiffies
;
1747 __cfq_slice_expired(cfqd
, cfqq
, 1);
1748 __cfq_set_active_queue(cfqd
, cfqq
);
1752 * should really be a ll_rw_blk.c helper
1754 static void cfq_start_queueing(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1756 request_queue_t
*q
= cfqd
->queue
;
1758 if (!blk_queue_plugged(q
))
1761 __generic_unplug_device(q
);
1765 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1766 * something we should do about it
1769 cfq_crq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1772 const int sync
= cfq_crq_is_sync(crq
);
1774 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
1777 struct cfq_io_context
*cic
= crq
->io_context
;
1779 cfq_update_io_thinktime(cfqd
, cic
);
1780 cfq_update_idle_window(cfqd
, cfqq
, cic
);
1782 cic
->last_queue
= jiffies
;
1785 if (cfqq
== cfqd
->active_queue
) {
1787 * if we are waiting for a request for this queue, let it rip
1788 * immediately and flag that we must not expire this queue
1791 if (cfq_cfqq_wait_request(cfqq
)) {
1792 cfq_mark_cfqq_must_dispatch(cfqq
);
1793 del_timer(&cfqd
->idle_slice_timer
);
1794 cfq_start_queueing(cfqd
, cfqq
);
1796 } else if (cfq_should_preempt(cfqd
, cfqq
, crq
)) {
1798 * not the active queue - expire current slice if it is
1799 * idle and has expired it's mean thinktime or this new queue
1800 * has some old slice time left and is of higher priority
1802 cfq_preempt_queue(cfqd
, cfqq
);
1803 cfq_mark_cfqq_must_dispatch(cfqq
);
1804 cfq_start_queueing(cfqd
, cfqq
);
1808 static void cfq_enqueue(struct cfq_data
*cfqd
, struct request
*rq
)
1810 struct cfq_rq
*crq
= RQ_DATA(rq
);
1811 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1813 cfq_init_prio_data(cfqq
);
1815 cfq_add_crq_rb(crq
);
1817 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
1819 if (rq_mergeable(rq
)) {
1820 cfq_add_crq_hash(cfqd
, crq
);
1822 if (!cfqd
->queue
->last_merge
)
1823 cfqd
->queue
->last_merge
= rq
;
1826 cfq_crq_enqueued(cfqd
, cfqq
, crq
);
1830 cfq_insert_request(request_queue_t
*q
, struct request
*rq
, int where
)
1832 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1835 case ELEVATOR_INSERT_BACK
:
1836 while (cfq_dispatch_requests(q
, INT_MAX
, 1))
1838 list_add_tail(&rq
->queuelist
, &q
->queue_head
);
1840 * If we were idling with pending requests on
1841 * inactive cfqqs, force dispatching will
1842 * remove the idle timer and the queue won't
1843 * be kicked by __make_request() afterward.
1846 cfq_schedule_dispatch(cfqd
);
1848 case ELEVATOR_INSERT_FRONT
:
1849 list_add(&rq
->queuelist
, &q
->queue_head
);
1851 case ELEVATOR_INSERT_SORT
:
1852 BUG_ON(!blk_fs_request(rq
));
1853 cfq_enqueue(cfqd
, rq
);
1856 printk("%s: bad insert point %d\n", __FUNCTION__
,where
);
1861 static void cfq_completed_request(request_queue_t
*q
, struct request
*rq
)
1863 struct cfq_rq
*crq
= RQ_DATA(rq
);
1864 struct cfq_queue
*cfqq
;
1866 if (unlikely(!blk_fs_request(rq
)))
1869 cfqq
= crq
->cfq_queue
;
1871 if (cfq_crq_in_flight(crq
)) {
1872 const int sync
= cfq_crq_is_sync(crq
);
1874 WARN_ON(!cfqq
->on_dispatch
[sync
]);
1875 cfqq
->on_dispatch
[sync
]--;
1878 cfq_account_completion(cfqq
, crq
);
1881 static struct request
*
1882 cfq_former_request(request_queue_t
*q
, struct request
*rq
)
1884 struct cfq_rq
*crq
= RQ_DATA(rq
);
1885 struct rb_node
*rbprev
= rb_prev(&crq
->rb_node
);
1888 return rb_entry_crq(rbprev
)->request
;
1893 static struct request
*
1894 cfq_latter_request(request_queue_t
*q
, struct request
*rq
)
1896 struct cfq_rq
*crq
= RQ_DATA(rq
);
1897 struct rb_node
*rbnext
= rb_next(&crq
->rb_node
);
1900 return rb_entry_crq(rbnext
)->request
;
1906 * we temporarily boost lower priority queues if they are holding fs exclusive
1907 * resources. they are boosted to normal prio (CLASS_BE/4)
1909 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
1911 const int ioprio_class
= cfqq
->ioprio_class
;
1912 const int ioprio
= cfqq
->ioprio
;
1914 if (has_fs_excl()) {
1916 * boost idle prio on transactions that would lock out other
1917 * users of the filesystem
1919 if (cfq_class_idle(cfqq
))
1920 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1921 if (cfqq
->ioprio
> IOPRIO_NORM
)
1922 cfqq
->ioprio
= IOPRIO_NORM
;
1925 * check if we need to unboost the queue
1927 if (cfqq
->ioprio_class
!= cfqq
->org_ioprio_class
)
1928 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
1929 if (cfqq
->ioprio
!= cfqq
->org_ioprio
)
1930 cfqq
->ioprio
= cfqq
->org_ioprio
;
1934 * refile between round-robin lists if we moved the priority class
1936 if ((ioprio_class
!= cfqq
->ioprio_class
|| ioprio
!= cfqq
->ioprio
) &&
1937 cfq_cfqq_on_rr(cfqq
))
1938 cfq_resort_rr_list(cfqq
, 0);
1941 static inline pid_t
cfq_queue_pid(struct task_struct
*task
, int rw
)
1943 if (rw
== READ
|| process_sync(task
))
1946 return CFQ_KEY_ASYNC
;
1950 __cfq_may_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1951 struct task_struct
*task
, int rw
)
1954 if ((cfq_cfqq_wait_request(cfqq
) || cfq_cfqq_must_alloc(cfqq
)) &&
1955 !cfq_cfqq_must_alloc_slice(cfqq
)) {
1956 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1957 return ELV_MQUEUE_MUST
;
1960 return ELV_MQUEUE_MAY
;
1962 if (!cfqq
|| task
->flags
& PF_MEMALLOC
)
1963 return ELV_MQUEUE_MAY
;
1964 if (!cfqq
->allocated
[rw
] || cfq_cfqq_must_alloc(cfqq
)) {
1965 if (cfq_cfqq_wait_request(cfqq
))
1966 return ELV_MQUEUE_MUST
;
1969 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1970 * can quickly flood the queue with writes from a single task
1972 if (rw
== READ
|| !cfq_cfqq_must_alloc_slice(cfqq
)) {
1973 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1974 return ELV_MQUEUE_MUST
;
1977 return ELV_MQUEUE_MAY
;
1979 if (cfq_class_idle(cfqq
))
1980 return ELV_MQUEUE_NO
;
1981 if (cfqq
->allocated
[rw
] >= cfqd
->max_queued
) {
1982 struct io_context
*ioc
= get_io_context(GFP_ATOMIC
);
1983 int ret
= ELV_MQUEUE_NO
;
1985 if (ioc
&& ioc
->nr_batch_requests
)
1986 ret
= ELV_MQUEUE_MAY
;
1988 put_io_context(ioc
);
1992 return ELV_MQUEUE_MAY
;
1996 static int cfq_may_queue(request_queue_t
*q
, int rw
, struct bio
*bio
)
1998 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1999 struct task_struct
*tsk
= current
;
2000 struct cfq_queue
*cfqq
;
2003 * don't force setup of a queue from here, as a call to may_queue
2004 * does not necessarily imply that a request actually will be queued.
2005 * so just lookup a possibly existing queue, or return 'may queue'
2008 cfqq
= cfq_find_cfq_hash(cfqd
, cfq_queue_pid(tsk
, rw
), tsk
->ioprio
);
2010 cfq_init_prio_data(cfqq
);
2011 cfq_prio_boost(cfqq
);
2013 return __cfq_may_queue(cfqd
, cfqq
, tsk
, rw
);
2016 return ELV_MQUEUE_MAY
;
2019 static void cfq_check_waiters(request_queue_t
*q
, struct cfq_queue
*cfqq
)
2021 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2022 struct request_list
*rl
= &q
->rq
;
2024 if (cfqq
->allocated
[READ
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
2026 if (waitqueue_active(&rl
->wait
[READ
]))
2027 wake_up(&rl
->wait
[READ
]);
2030 if (cfqq
->allocated
[WRITE
] <= cfqd
->max_queued
|| cfqd
->rq_starved
) {
2032 if (waitqueue_active(&rl
->wait
[WRITE
]))
2033 wake_up(&rl
->wait
[WRITE
]);
2038 * queue lock held here
2040 static void cfq_put_request(request_queue_t
*q
, struct request
*rq
)
2042 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2043 struct cfq_rq
*crq
= RQ_DATA(rq
);
2046 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
2047 const int rw
= rq_data_dir(rq
);
2049 BUG_ON(!cfqq
->allocated
[rw
]);
2050 cfqq
->allocated
[rw
]--;
2052 put_io_context(crq
->io_context
->ioc
);
2054 mempool_free(crq
, cfqd
->crq_pool
);
2055 rq
->elevator_private
= NULL
;
2057 cfq_check_waiters(q
, cfqq
);
2058 cfq_put_queue(cfqq
);
2063 * Allocate cfq data structures associated with this request.
2066 cfq_set_request(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
,
2069 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2070 struct task_struct
*tsk
= current
;
2071 struct cfq_io_context
*cic
;
2072 const int rw
= rq_data_dir(rq
);
2073 pid_t key
= cfq_queue_pid(tsk
, rw
);
2074 struct cfq_queue
*cfqq
;
2076 unsigned long flags
;
2078 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2080 cic
= cfq_get_io_context(cfqd
, key
, gfp_mask
);
2082 spin_lock_irqsave(q
->queue_lock
, flags
);
2088 cfqq
= cfq_get_queue(cfqd
, key
, tsk
->ioprio
, gfp_mask
);
2096 cfqq
->allocated
[rw
]++;
2097 cfq_clear_cfqq_must_alloc(cfqq
);
2098 cfqd
->rq_starved
= 0;
2099 atomic_inc(&cfqq
->ref
);
2100 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2102 crq
= mempool_alloc(cfqd
->crq_pool
, gfp_mask
);
2104 RB_CLEAR(&crq
->rb_node
);
2107 INIT_HLIST_NODE(&crq
->hash
);
2108 crq
->cfq_queue
= cfqq
;
2109 crq
->io_context
= cic
;
2110 cfq_clear_crq_in_flight(crq
);
2111 cfq_clear_crq_in_driver(crq
);
2112 cfq_clear_crq_requeued(crq
);
2114 if (rw
== READ
|| process_sync(tsk
))
2115 cfq_mark_crq_is_sync(crq
);
2117 cfq_clear_crq_is_sync(crq
);
2119 rq
->elevator_private
= crq
;
2123 spin_lock_irqsave(q
->queue_lock
, flags
);
2124 cfqq
->allocated
[rw
]--;
2125 if (!(cfqq
->allocated
[0] + cfqq
->allocated
[1]))
2126 cfq_mark_cfqq_must_alloc(cfqq
);
2127 cfq_put_queue(cfqq
);
2130 put_io_context(cic
->ioc
);
2132 * mark us rq allocation starved. we need to kickstart the process
2133 * ourselves if there are no pending requests that can do it for us.
2134 * that would be an extremely rare OOM situation
2136 cfqd
->rq_starved
= 1;
2137 cfq_schedule_dispatch(cfqd
);
2138 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2142 static void cfq_kick_queue(void *data
)
2144 request_queue_t
*q
= data
;
2145 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2146 unsigned long flags
;
2148 spin_lock_irqsave(q
->queue_lock
, flags
);
2150 if (cfqd
->rq_starved
) {
2151 struct request_list
*rl
= &q
->rq
;
2154 * we aren't guaranteed to get a request after this, but we
2155 * have to be opportunistic
2158 if (waitqueue_active(&rl
->wait
[READ
]))
2159 wake_up(&rl
->wait
[READ
]);
2160 if (waitqueue_active(&rl
->wait
[WRITE
]))
2161 wake_up(&rl
->wait
[WRITE
]);
2166 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2170 * Timer running if the active_queue is currently idling inside its time slice
2172 static void cfq_idle_slice_timer(unsigned long data
)
2174 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2175 struct cfq_queue
*cfqq
;
2176 unsigned long flags
;
2178 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2180 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
2181 unsigned long now
= jiffies
;
2186 if (time_after(now
, cfqq
->slice_end
))
2190 * only expire and reinvoke request handler, if there are
2191 * other queues with pending requests
2193 if (!cfq_pending_requests(cfqd
)) {
2194 cfqd
->idle_slice_timer
.expires
= min(now
+ cfqd
->cfq_slice_idle
, cfqq
->slice_end
);
2195 add_timer(&cfqd
->idle_slice_timer
);
2200 * not expired and it has a request pending, let it dispatch
2202 if (!RB_EMPTY(&cfqq
->sort_list
)) {
2203 cfq_mark_cfqq_must_dispatch(cfqq
);
2208 cfq_slice_expired(cfqd
, 0);
2210 cfq_schedule_dispatch(cfqd
);
2212 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2216 * Timer running if an idle class queue is waiting for service
2218 static void cfq_idle_class_timer(unsigned long data
)
2220 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2221 unsigned long flags
, end
;
2223 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2226 * race with a non-idle queue, reset timer
2228 end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
2229 if (!time_after_eq(jiffies
, end
)) {
2230 cfqd
->idle_class_timer
.expires
= end
;
2231 add_timer(&cfqd
->idle_class_timer
);
2233 cfq_schedule_dispatch(cfqd
);
2235 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2238 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2240 del_timer_sync(&cfqd
->idle_slice_timer
);
2241 del_timer_sync(&cfqd
->idle_class_timer
);
2242 blk_sync_queue(cfqd
->queue
);
2245 static void cfq_put_cfqd(struct cfq_data
*cfqd
)
2247 request_queue_t
*q
= cfqd
->queue
;
2249 if (!atomic_dec_and_test(&cfqd
->ref
))
2254 cfq_shutdown_timer_wq(cfqd
);
2255 q
->elevator
->elevator_data
= NULL
;
2257 mempool_destroy(cfqd
->crq_pool
);
2258 kfree(cfqd
->crq_hash
);
2259 kfree(cfqd
->cfq_hash
);
2263 static void cfq_exit_queue(elevator_t
*e
)
2265 struct cfq_data
*cfqd
= e
->elevator_data
;
2267 cfq_shutdown_timer_wq(cfqd
);
2271 static int cfq_init_queue(request_queue_t
*q
, elevator_t
*e
)
2273 struct cfq_data
*cfqd
;
2276 cfqd
= kmalloc(sizeof(*cfqd
), GFP_KERNEL
);
2280 memset(cfqd
, 0, sizeof(*cfqd
));
2282 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2283 INIT_LIST_HEAD(&cfqd
->rr_list
[i
]);
2285 INIT_LIST_HEAD(&cfqd
->busy_rr
);
2286 INIT_LIST_HEAD(&cfqd
->cur_rr
);
2287 INIT_LIST_HEAD(&cfqd
->idle_rr
);
2288 INIT_LIST_HEAD(&cfqd
->empty_list
);
2290 cfqd
->crq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_MHASH_ENTRIES
, GFP_KERNEL
);
2291 if (!cfqd
->crq_hash
)
2294 cfqd
->cfq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_QHASH_ENTRIES
, GFP_KERNEL
);
2295 if (!cfqd
->cfq_hash
)
2298 cfqd
->crq_pool
= mempool_create(BLKDEV_MIN_RQ
, mempool_alloc_slab
, mempool_free_slab
, crq_pool
);
2299 if (!cfqd
->crq_pool
)
2302 for (i
= 0; i
< CFQ_MHASH_ENTRIES
; i
++)
2303 INIT_HLIST_HEAD(&cfqd
->crq_hash
[i
]);
2304 for (i
= 0; i
< CFQ_QHASH_ENTRIES
; i
++)
2305 INIT_HLIST_HEAD(&cfqd
->cfq_hash
[i
]);
2307 e
->elevator_data
= cfqd
;
2310 atomic_inc(&q
->refcnt
);
2312 cfqd
->max_queued
= q
->nr_requests
/ 4;
2313 q
->nr_batching
= cfq_queued
;
2315 init_timer(&cfqd
->idle_slice_timer
);
2316 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
2317 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
2319 init_timer(&cfqd
->idle_class_timer
);
2320 cfqd
->idle_class_timer
.function
= cfq_idle_class_timer
;
2321 cfqd
->idle_class_timer
.data
= (unsigned long) cfqd
;
2323 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
, q
);
2325 atomic_set(&cfqd
->ref
, 1);
2327 cfqd
->cfq_queued
= cfq_queued
;
2328 cfqd
->cfq_quantum
= cfq_quantum
;
2329 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
2330 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
2331 cfqd
->cfq_back_max
= cfq_back_max
;
2332 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
2333 cfqd
->cfq_slice
[0] = cfq_slice_async
;
2334 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
2335 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
2336 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
2337 cfqd
->cfq_max_depth
= cfq_max_depth
;
2341 kfree(cfqd
->cfq_hash
);
2343 kfree(cfqd
->crq_hash
);
2349 static void cfq_slab_kill(void)
2352 kmem_cache_destroy(crq_pool
);
2354 kmem_cache_destroy(cfq_pool
);
2356 kmem_cache_destroy(cfq_ioc_pool
);
2359 static int __init
cfq_slab_setup(void)
2361 crq_pool
= kmem_cache_create("crq_pool", sizeof(struct cfq_rq
), 0, 0,
2366 cfq_pool
= kmem_cache_create("cfq_pool", sizeof(struct cfq_queue
), 0, 0,
2371 cfq_ioc_pool
= kmem_cache_create("cfq_ioc_pool",
2372 sizeof(struct cfq_io_context
), 0, 0, NULL
, NULL
);
2383 * sysfs parts below -->
2385 struct cfq_fs_entry
{
2386 struct attribute attr
;
2387 ssize_t (*show
)(struct cfq_data
*, char *);
2388 ssize_t (*store
)(struct cfq_data
*, const char *, size_t);
2392 cfq_var_show(unsigned int var
, char *page
)
2394 return sprintf(page
, "%d\n", var
);
2398 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
2400 char *p
= (char *) page
;
2402 *var
= simple_strtoul(p
, &p
, 10);
2406 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2407 static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2409 unsigned int __data = __VAR; \
2411 __data = jiffies_to_msecs(__data); \
2412 return cfq_var_show(__data, (page)); \
2414 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
2415 SHOW_FUNCTION(cfq_queued_show
, cfqd
->cfq_queued
, 0);
2416 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
2417 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
2418 SHOW_FUNCTION(cfq_back_max_show
, cfqd
->cfq_back_max
, 0);
2419 SHOW_FUNCTION(cfq_back_penalty_show
, cfqd
->cfq_back_penalty
, 0);
2420 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
2421 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
2422 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
2423 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
2424 SHOW_FUNCTION(cfq_max_depth_show
, cfqd
->cfq_max_depth
, 0);
2425 #undef SHOW_FUNCTION
2427 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2428 static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2430 unsigned int __data; \
2431 int ret = cfq_var_store(&__data, (page), count); \
2432 if (__data < (MIN)) \
2434 else if (__data > (MAX)) \
2437 *(__PTR) = msecs_to_jiffies(__data); \
2439 *(__PTR) = __data; \
2442 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
2443 STORE_FUNCTION(cfq_queued_store
, &cfqd
->cfq_queued
, 1, UINT_MAX
, 0);
2444 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1, UINT_MAX
, 1);
2445 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1, UINT_MAX
, 1);
2446 STORE_FUNCTION(cfq_back_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
2447 STORE_FUNCTION(cfq_back_penalty_store
, &cfqd
->cfq_back_penalty
, 1, UINT_MAX
, 0);
2448 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
2449 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
2450 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
2451 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1, UINT_MAX
, 0);
2452 STORE_FUNCTION(cfq_max_depth_store
, &cfqd
->cfq_max_depth
, 1, UINT_MAX
, 0);
2453 #undef STORE_FUNCTION
2455 static struct cfq_fs_entry cfq_quantum_entry
= {
2456 .attr
= {.name
= "quantum", .mode
= S_IRUGO
| S_IWUSR
},
2457 .show
= cfq_quantum_show
,
2458 .store
= cfq_quantum_store
,
2460 static struct cfq_fs_entry cfq_queued_entry
= {
2461 .attr
= {.name
= "queued", .mode
= S_IRUGO
| S_IWUSR
},
2462 .show
= cfq_queued_show
,
2463 .store
= cfq_queued_store
,
2465 static struct cfq_fs_entry cfq_fifo_expire_sync_entry
= {
2466 .attr
= {.name
= "fifo_expire_sync", .mode
= S_IRUGO
| S_IWUSR
},
2467 .show
= cfq_fifo_expire_sync_show
,
2468 .store
= cfq_fifo_expire_sync_store
,
2470 static struct cfq_fs_entry cfq_fifo_expire_async_entry
= {
2471 .attr
= {.name
= "fifo_expire_async", .mode
= S_IRUGO
| S_IWUSR
},
2472 .show
= cfq_fifo_expire_async_show
,
2473 .store
= cfq_fifo_expire_async_store
,
2475 static struct cfq_fs_entry cfq_back_max_entry
= {
2476 .attr
= {.name
= "back_seek_max", .mode
= S_IRUGO
| S_IWUSR
},
2477 .show
= cfq_back_max_show
,
2478 .store
= cfq_back_max_store
,
2480 static struct cfq_fs_entry cfq_back_penalty_entry
= {
2481 .attr
= {.name
= "back_seek_penalty", .mode
= S_IRUGO
| S_IWUSR
},
2482 .show
= cfq_back_penalty_show
,
2483 .store
= cfq_back_penalty_store
,
2485 static struct cfq_fs_entry cfq_slice_sync_entry
= {
2486 .attr
= {.name
= "slice_sync", .mode
= S_IRUGO
| S_IWUSR
},
2487 .show
= cfq_slice_sync_show
,
2488 .store
= cfq_slice_sync_store
,
2490 static struct cfq_fs_entry cfq_slice_async_entry
= {
2491 .attr
= {.name
= "slice_async", .mode
= S_IRUGO
| S_IWUSR
},
2492 .show
= cfq_slice_async_show
,
2493 .store
= cfq_slice_async_store
,
2495 static struct cfq_fs_entry cfq_slice_async_rq_entry
= {
2496 .attr
= {.name
= "slice_async_rq", .mode
= S_IRUGO
| S_IWUSR
},
2497 .show
= cfq_slice_async_rq_show
,
2498 .store
= cfq_slice_async_rq_store
,
2500 static struct cfq_fs_entry cfq_slice_idle_entry
= {
2501 .attr
= {.name
= "slice_idle", .mode
= S_IRUGO
| S_IWUSR
},
2502 .show
= cfq_slice_idle_show
,
2503 .store
= cfq_slice_idle_store
,
2505 static struct cfq_fs_entry cfq_max_depth_entry
= {
2506 .attr
= {.name
= "max_depth", .mode
= S_IRUGO
| S_IWUSR
},
2507 .show
= cfq_max_depth_show
,
2508 .store
= cfq_max_depth_store
,
2511 static struct attribute
*default_attrs
[] = {
2512 &cfq_quantum_entry
.attr
,
2513 &cfq_queued_entry
.attr
,
2514 &cfq_fifo_expire_sync_entry
.attr
,
2515 &cfq_fifo_expire_async_entry
.attr
,
2516 &cfq_back_max_entry
.attr
,
2517 &cfq_back_penalty_entry
.attr
,
2518 &cfq_slice_sync_entry
.attr
,
2519 &cfq_slice_async_entry
.attr
,
2520 &cfq_slice_async_rq_entry
.attr
,
2521 &cfq_slice_idle_entry
.attr
,
2522 &cfq_max_depth_entry
.attr
,
2526 #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2529 cfq_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
2531 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2532 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2537 return entry
->show(e
->elevator_data
, page
);
2541 cfq_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
2542 const char *page
, size_t length
)
2544 elevator_t
*e
= container_of(kobj
, elevator_t
, kobj
);
2545 struct cfq_fs_entry
*entry
= to_cfq(attr
);
2550 return entry
->store(e
->elevator_data
, page
, length
);
2553 static struct sysfs_ops cfq_sysfs_ops
= {
2554 .show
= cfq_attr_show
,
2555 .store
= cfq_attr_store
,
2558 static struct kobj_type cfq_ktype
= {
2559 .sysfs_ops
= &cfq_sysfs_ops
,
2560 .default_attrs
= default_attrs
,
2563 static struct elevator_type iosched_cfq
= {
2565 .elevator_merge_fn
= cfq_merge
,
2566 .elevator_merged_fn
= cfq_merged_request
,
2567 .elevator_merge_req_fn
= cfq_merged_requests
,
2568 .elevator_next_req_fn
= cfq_next_request
,
2569 .elevator_add_req_fn
= cfq_insert_request
,
2570 .elevator_remove_req_fn
= cfq_remove_request
,
2571 .elevator_requeue_req_fn
= cfq_requeue_request
,
2572 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
2573 .elevator_queue_empty_fn
= cfq_queue_empty
,
2574 .elevator_completed_req_fn
= cfq_completed_request
,
2575 .elevator_former_req_fn
= cfq_former_request
,
2576 .elevator_latter_req_fn
= cfq_latter_request
,
2577 .elevator_set_req_fn
= cfq_set_request
,
2578 .elevator_put_req_fn
= cfq_put_request
,
2579 .elevator_may_queue_fn
= cfq_may_queue
,
2580 .elevator_init_fn
= cfq_init_queue
,
2581 .elevator_exit_fn
= cfq_exit_queue
,
2583 .elevator_ktype
= &cfq_ktype
,
2584 .elevator_name
= "cfq",
2585 .elevator_owner
= THIS_MODULE
,
2588 static int __init
cfq_init(void)
2593 * could be 0 on HZ < 1000 setups
2595 if (!cfq_slice_async
)
2596 cfq_slice_async
= 1;
2597 if (!cfq_slice_idle
)
2600 if (cfq_slab_setup())
2603 ret
= elv_register(&iosched_cfq
);
2610 static void __exit
cfq_exit(void)
2612 struct task_struct
*g
, *p
;
2613 unsigned long flags
;
2615 read_lock_irqsave(&tasklist_lock
, flags
);
2618 * iterate each process in the system, removing our io_context
2620 do_each_thread(g
, p
) {
2621 struct io_context
*ioc
= p
->io_context
;
2623 if (ioc
&& ioc
->cic
) {
2624 ioc
->cic
->exit(ioc
->cic
);
2625 cfq_free_io_context(ioc
->cic
);
2628 } while_each_thread(g
, p
);
2630 read_unlock_irqrestore(&tasklist_lock
, flags
);
2633 elv_unregister(&iosched_cfq
);
2636 module_init(cfq_init
);
2637 module_exit(cfq_exit
);
2639 MODULE_AUTHOR("Jens Axboe");
2640 MODULE_LICENSE("GPL");
2641 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");