2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@suse.de>
9 #include <linux/config.h>
10 #include <linux/module.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/hash.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
20 static const int cfq_quantum
= 4; /* max queue in one round of service */
21 static const int cfq_queued
= 8; /* minimum rq allocate limit per-queue*/
22 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
23 static const int cfq_back_max
= 16 * 1024; /* maximum backwards seek, in KiB */
24 static const int cfq_back_penalty
= 2; /* penalty of a backwards seek */
26 static const int cfq_slice_sync
= HZ
/ 10;
27 static int cfq_slice_async
= HZ
/ 25;
28 static const int cfq_slice_async_rq
= 2;
29 static int cfq_slice_idle
= HZ
/ 70;
31 #define CFQ_IDLE_GRACE (HZ / 10)
32 #define CFQ_SLICE_SCALE (5)
34 #define CFQ_KEY_ASYNC (0)
36 static DEFINE_SPINLOCK(cfq_exit_lock
);
39 * for the hash of cfqq inside the cfqd
41 #define CFQ_QHASH_SHIFT 6
42 #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
43 #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
46 * for the hash of crq inside the cfqq
48 #define CFQ_MHASH_SHIFT 6
49 #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
50 #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
51 #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
52 #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
53 #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
55 #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
56 #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
58 #define RQ_DATA(rq) (rq)->elevator_private
63 #define RB_EMPTY(node) ((node)->rb_node == NULL)
64 #define RB_CLEAR(node) do { \
65 memset(node, 0, sizeof(*node)); \
67 #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
68 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
69 #define rq_rb_key(rq) (rq)->sector
71 static kmem_cache_t
*crq_pool
;
72 static kmem_cache_t
*cfq_pool
;
73 static kmem_cache_t
*cfq_ioc_pool
;
75 static atomic_t ioc_count
= ATOMIC_INIT(0);
76 static struct completion
*ioc_gone
;
78 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
79 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
80 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
81 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
86 #define cfq_cfqq_dispatched(cfqq) \
87 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
89 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
91 #define cfq_cfqq_sync(cfqq) \
92 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
94 #define sample_valid(samples) ((samples) > 80)
97 * Per block device queue structure
100 request_queue_t
*queue
;
103 * rr list of queues with requests and the count of them
105 struct list_head rr_list
[CFQ_PRIO_LISTS
];
106 struct list_head busy_rr
;
107 struct list_head cur_rr
;
108 struct list_head idle_rr
;
109 unsigned int busy_queues
;
112 * non-ordered list of empty cfqq's
114 struct list_head empty_list
;
119 struct hlist_head
*cfq_hash
;
122 * global crq hash for all queues
124 struct hlist_head
*crq_hash
;
132 * schedule slice state info
135 * idle window management
137 struct timer_list idle_slice_timer
;
138 struct work_struct unplug_work
;
140 struct cfq_queue
*active_queue
;
141 struct cfq_io_context
*active_cic
;
142 int cur_prio
, cur_end_prio
;
143 unsigned int dispatch_slice
;
145 struct timer_list idle_class_timer
;
147 sector_t last_sector
;
148 unsigned long last_end_request
;
150 unsigned int rq_starved
;
153 * tunables, see top of file
155 unsigned int cfq_quantum
;
156 unsigned int cfq_queued
;
157 unsigned int cfq_fifo_expire
[2];
158 unsigned int cfq_back_penalty
;
159 unsigned int cfq_back_max
;
160 unsigned int cfq_slice
[2];
161 unsigned int cfq_slice_async_rq
;
162 unsigned int cfq_slice_idle
;
164 struct list_head cic_list
;
168 * Per process-grouping structure
171 /* reference count */
173 /* parent cfq_data */
174 struct cfq_data
*cfqd
;
175 /* cfqq lookup hash */
176 struct hlist_node cfq_hash
;
179 /* on either rr or empty list of cfqd */
180 struct list_head cfq_list
;
181 /* sorted list of pending requests */
182 struct rb_root sort_list
;
183 /* if fifo isn't expired, next request to serve */
184 struct cfq_rq
*next_crq
;
185 /* requests queued in sort_list */
187 /* currently allocated requests */
189 /* fifo list of requests in sort_list */
190 struct list_head fifo
;
192 unsigned long slice_start
;
193 unsigned long slice_end
;
194 unsigned long slice_left
;
195 unsigned long service_last
;
197 /* number of requests that are on the dispatch list */
200 /* io prio of this group */
201 unsigned short ioprio
, org_ioprio
;
202 unsigned short ioprio_class
, org_ioprio_class
;
204 /* various state flags, see below */
209 struct rb_node rb_node
;
211 struct request
*request
;
212 struct hlist_node hash
;
214 struct cfq_queue
*cfq_queue
;
215 struct cfq_io_context
*io_context
;
217 unsigned int crq_flags
;
220 enum cfqq_state_flags
{
221 CFQ_CFQQ_FLAG_on_rr
= 0,
222 CFQ_CFQQ_FLAG_wait_request
,
223 CFQ_CFQQ_FLAG_must_alloc
,
224 CFQ_CFQQ_FLAG_must_alloc_slice
,
225 CFQ_CFQQ_FLAG_must_dispatch
,
226 CFQ_CFQQ_FLAG_fifo_expire
,
227 CFQ_CFQQ_FLAG_idle_window
,
228 CFQ_CFQQ_FLAG_prio_changed
,
231 #define CFQ_CFQQ_FNS(name) \
232 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
234 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
236 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
238 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
240 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
242 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
246 CFQ_CFQQ_FNS(wait_request
);
247 CFQ_CFQQ_FNS(must_alloc
);
248 CFQ_CFQQ_FNS(must_alloc_slice
);
249 CFQ_CFQQ_FNS(must_dispatch
);
250 CFQ_CFQQ_FNS(fifo_expire
);
251 CFQ_CFQQ_FNS(idle_window
);
252 CFQ_CFQQ_FNS(prio_changed
);
255 enum cfq_rq_state_flags
{
256 CFQ_CRQ_FLAG_is_sync
= 0,
259 #define CFQ_CRQ_FNS(name) \
260 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
262 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
264 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
266 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
268 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
270 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
273 CFQ_CRQ_FNS(is_sync
);
276 static struct cfq_queue
*cfq_find_cfq_hash(struct cfq_data
*, unsigned int, unsigned short);
277 static void cfq_dispatch_insert(request_queue_t
*, struct cfq_rq
*);
278 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, struct task_struct
*tsk
, gfp_t gfp_mask
);
280 #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
283 * lots of deadline iosched dupes, can be abstracted later...
285 static inline void cfq_del_crq_hash(struct cfq_rq
*crq
)
287 hlist_del_init(&crq
->hash
);
290 static inline void cfq_add_crq_hash(struct cfq_data
*cfqd
, struct cfq_rq
*crq
)
292 const int hash_idx
= CFQ_MHASH_FN(rq_hash_key(crq
->request
));
294 hlist_add_head(&crq
->hash
, &cfqd
->crq_hash
[hash_idx
]);
297 static struct request
*cfq_find_rq_hash(struct cfq_data
*cfqd
, sector_t offset
)
299 struct hlist_head
*hash_list
= &cfqd
->crq_hash
[CFQ_MHASH_FN(offset
)];
300 struct hlist_node
*entry
, *next
;
302 hlist_for_each_safe(entry
, next
, hash_list
) {
303 struct cfq_rq
*crq
= list_entry_hash(entry
);
304 struct request
*__rq
= crq
->request
;
306 if (!rq_mergeable(__rq
)) {
307 cfq_del_crq_hash(crq
);
311 if (rq_hash_key(__rq
) == offset
)
319 * scheduler run of queue, if there are requests pending and no one in the
320 * driver that will restart queueing
322 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
324 if (cfqd
->busy_queues
)
325 kblockd_schedule_work(&cfqd
->unplug_work
);
328 static int cfq_queue_empty(request_queue_t
*q
)
330 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
332 return !cfqd
->busy_queues
;
335 static inline pid_t
cfq_queue_pid(struct task_struct
*task
, int rw
)
337 if (rw
== READ
|| process_sync(task
))
340 return CFQ_KEY_ASYNC
;
344 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
345 * We choose the request that is closest to the head right now. Distance
346 * behind the head is penalized and only allowed to a certain extent.
348 static struct cfq_rq
*
349 cfq_choose_req(struct cfq_data
*cfqd
, struct cfq_rq
*crq1
, struct cfq_rq
*crq2
)
351 sector_t last
, s1
, s2
, d1
= 0, d2
= 0;
352 unsigned long back_max
;
353 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
354 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
355 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
357 if (crq1
== NULL
|| crq1
== crq2
)
362 if (cfq_crq_is_sync(crq1
) && !cfq_crq_is_sync(crq2
))
364 else if (cfq_crq_is_sync(crq2
) && !cfq_crq_is_sync(crq1
))
367 s1
= crq1
->request
->sector
;
368 s2
= crq2
->request
->sector
;
370 last
= cfqd
->last_sector
;
373 * by definition, 1KiB is 2 sectors
375 back_max
= cfqd
->cfq_back_max
* 2;
378 * Strict one way elevator _except_ in the case where we allow
379 * short backward seeks which are biased as twice the cost of a
380 * similar forward seek.
384 else if (s1
+ back_max
>= last
)
385 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
387 wrap
|= CFQ_RQ1_WRAP
;
391 else if (s2
+ back_max
>= last
)
392 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
394 wrap
|= CFQ_RQ2_WRAP
;
396 /* Found required data */
399 * By doing switch() on the bit mask "wrap" we avoid having to
400 * check two variables for all permutations: --> faster!
403 case 0: /* common case for CFQ: crq1 and crq2 not wrapped */
419 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both crqs wrapped */
422 * Since both rqs are wrapped,
423 * start with the one that's further behind head
424 * (--> only *one* back seek required),
425 * since back seek takes more time than forward.
435 * would be nice to take fifo expire time into account as well
437 static struct cfq_rq
*
438 cfq_find_next_crq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
441 struct cfq_rq
*crq_next
= NULL
, *crq_prev
= NULL
;
442 struct rb_node
*rbnext
, *rbprev
;
444 if (!(rbnext
= rb_next(&last
->rb_node
))) {
445 rbnext
= rb_first(&cfqq
->sort_list
);
446 if (rbnext
== &last
->rb_node
)
450 rbprev
= rb_prev(&last
->rb_node
);
453 crq_prev
= rb_entry_crq(rbprev
);
455 crq_next
= rb_entry_crq(rbnext
);
457 return cfq_choose_req(cfqd
, crq_next
, crq_prev
);
460 static void cfq_update_next_crq(struct cfq_rq
*crq
)
462 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
464 if (cfqq
->next_crq
== crq
)
465 cfqq
->next_crq
= cfq_find_next_crq(cfqq
->cfqd
, cfqq
, crq
);
468 static void cfq_resort_rr_list(struct cfq_queue
*cfqq
, int preempted
)
470 struct cfq_data
*cfqd
= cfqq
->cfqd
;
471 struct list_head
*list
, *entry
;
473 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
475 list_del(&cfqq
->cfq_list
);
477 if (cfq_class_rt(cfqq
))
478 list
= &cfqd
->cur_rr
;
479 else if (cfq_class_idle(cfqq
))
480 list
= &cfqd
->idle_rr
;
483 * if cfqq has requests in flight, don't allow it to be
484 * found in cfq_set_active_queue before it has finished them.
485 * this is done to increase fairness between a process that
486 * has lots of io pending vs one that only generates one
487 * sporadically or synchronously
489 if (cfq_cfqq_dispatched(cfqq
))
490 list
= &cfqd
->busy_rr
;
492 list
= &cfqd
->rr_list
[cfqq
->ioprio
];
496 * if queue was preempted, just add to front to be fair. busy_rr
497 * isn't sorted, but insert at the back for fairness.
499 if (preempted
|| list
== &cfqd
->busy_rr
) {
503 list_add_tail(&cfqq
->cfq_list
, list
);
508 * sort by when queue was last serviced
511 while ((entry
= entry
->prev
) != list
) {
512 struct cfq_queue
*__cfqq
= list_entry_cfqq(entry
);
514 if (!__cfqq
->service_last
)
516 if (time_before(__cfqq
->service_last
, cfqq
->service_last
))
520 list_add(&cfqq
->cfq_list
, entry
);
524 * add to busy list of queues for service, trying to be fair in ordering
525 * the pending list according to last request service
528 cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
530 BUG_ON(cfq_cfqq_on_rr(cfqq
));
531 cfq_mark_cfqq_on_rr(cfqq
);
534 cfq_resort_rr_list(cfqq
, 0);
538 cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
540 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
541 cfq_clear_cfqq_on_rr(cfqq
);
542 list_move(&cfqq
->cfq_list
, &cfqd
->empty_list
);
544 BUG_ON(!cfqd
->busy_queues
);
549 * rb tree support functions
551 static inline void cfq_del_crq_rb(struct cfq_rq
*crq
)
553 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
554 struct cfq_data
*cfqd
= cfqq
->cfqd
;
555 const int sync
= cfq_crq_is_sync(crq
);
557 BUG_ON(!cfqq
->queued
[sync
]);
558 cfqq
->queued
[sync
]--;
560 cfq_update_next_crq(crq
);
562 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
564 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY(&cfqq
->sort_list
))
565 cfq_del_cfqq_rr(cfqd
, cfqq
);
568 static struct cfq_rq
*
569 __cfq_add_crq_rb(struct cfq_rq
*crq
)
571 struct rb_node
**p
= &crq
->cfq_queue
->sort_list
.rb_node
;
572 struct rb_node
*parent
= NULL
;
573 struct cfq_rq
*__crq
;
577 __crq
= rb_entry_crq(parent
);
579 if (crq
->rb_key
< __crq
->rb_key
)
581 else if (crq
->rb_key
> __crq
->rb_key
)
587 rb_link_node(&crq
->rb_node
, parent
, p
);
591 static void cfq_add_crq_rb(struct cfq_rq
*crq
)
593 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
594 struct cfq_data
*cfqd
= cfqq
->cfqd
;
595 struct request
*rq
= crq
->request
;
596 struct cfq_rq
*__alias
;
598 crq
->rb_key
= rq_rb_key(rq
);
599 cfqq
->queued
[cfq_crq_is_sync(crq
)]++;
602 * looks a little odd, but the first insert might return an alias.
603 * if that happens, put the alias on the dispatch list
605 while ((__alias
= __cfq_add_crq_rb(crq
)) != NULL
)
606 cfq_dispatch_insert(cfqd
->queue
, __alias
);
608 rb_insert_color(&crq
->rb_node
, &cfqq
->sort_list
);
610 if (!cfq_cfqq_on_rr(cfqq
))
611 cfq_add_cfqq_rr(cfqd
, cfqq
);
614 * check if this request is a better next-serve candidate
616 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
620 cfq_reposition_crq_rb(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
622 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
623 cfqq
->queued
[cfq_crq_is_sync(crq
)]--;
628 static struct request
*
629 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
631 struct task_struct
*tsk
= current
;
632 pid_t key
= cfq_queue_pid(tsk
, bio_data_dir(bio
));
633 struct cfq_queue
*cfqq
;
637 cfqq
= cfq_find_cfq_hash(cfqd
, key
, tsk
->ioprio
);
641 sector
= bio
->bi_sector
+ bio_sectors(bio
);
642 n
= cfqq
->sort_list
.rb_node
;
644 struct cfq_rq
*crq
= rb_entry_crq(n
);
646 if (sector
< crq
->rb_key
)
648 else if (sector
> crq
->rb_key
)
658 static void cfq_activate_request(request_queue_t
*q
, struct request
*rq
)
660 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
662 cfqd
->rq_in_driver
++;
665 * If the depth is larger 1, it really could be queueing. But lets
666 * make the mark a little higher - idling could still be good for
667 * low queueing, and a low queueing number could also just indicate
668 * a SCSI mid layer like behaviour where limit+1 is often seen.
670 if (!cfqd
->hw_tag
&& cfqd
->rq_in_driver
> 4)
674 static void cfq_deactivate_request(request_queue_t
*q
, struct request
*rq
)
676 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
678 WARN_ON(!cfqd
->rq_in_driver
);
679 cfqd
->rq_in_driver
--;
682 static void cfq_remove_request(struct request
*rq
)
684 struct cfq_rq
*crq
= RQ_DATA(rq
);
686 list_del_init(&rq
->queuelist
);
688 cfq_del_crq_hash(crq
);
692 cfq_merge(request_queue_t
*q
, struct request
**req
, struct bio
*bio
)
694 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
695 struct request
*__rq
;
698 __rq
= cfq_find_rq_hash(cfqd
, bio
->bi_sector
);
699 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
700 ret
= ELEVATOR_BACK_MERGE
;
704 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
705 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
706 ret
= ELEVATOR_FRONT_MERGE
;
710 return ELEVATOR_NO_MERGE
;
716 static void cfq_merged_request(request_queue_t
*q
, struct request
*req
)
718 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
719 struct cfq_rq
*crq
= RQ_DATA(req
);
721 cfq_del_crq_hash(crq
);
722 cfq_add_crq_hash(cfqd
, crq
);
724 if (rq_rb_key(req
) != crq
->rb_key
) {
725 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
727 cfq_update_next_crq(crq
);
728 cfq_reposition_crq_rb(cfqq
, crq
);
733 cfq_merged_requests(request_queue_t
*q
, struct request
*rq
,
734 struct request
*next
)
736 cfq_merged_request(q
, rq
);
739 * reposition in fifo if next is older than rq
741 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
742 time_before(next
->start_time
, rq
->start_time
))
743 list_move(&rq
->queuelist
, &next
->queuelist
);
745 cfq_remove_request(next
);
749 __cfq_set_active_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
753 * stop potential idle class queues waiting service
755 del_timer(&cfqd
->idle_class_timer
);
757 cfqq
->slice_start
= jiffies
;
759 cfqq
->slice_left
= 0;
760 cfq_clear_cfqq_must_alloc_slice(cfqq
);
761 cfq_clear_cfqq_fifo_expire(cfqq
);
764 cfqd
->active_queue
= cfqq
;
768 * current cfqq expired its slice (or was too idle), select new one
771 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
774 unsigned long now
= jiffies
;
776 if (cfq_cfqq_wait_request(cfqq
))
777 del_timer(&cfqd
->idle_slice_timer
);
779 if (!preempted
&& !cfq_cfqq_dispatched(cfqq
)) {
780 cfqq
->service_last
= now
;
781 cfq_schedule_dispatch(cfqd
);
784 cfq_clear_cfqq_must_dispatch(cfqq
);
785 cfq_clear_cfqq_wait_request(cfqq
);
788 * store what was left of this slice, if the queue idled out
791 if (time_after(cfqq
->slice_end
, now
))
792 cfqq
->slice_left
= cfqq
->slice_end
- now
;
794 cfqq
->slice_left
= 0;
796 if (cfq_cfqq_on_rr(cfqq
))
797 cfq_resort_rr_list(cfqq
, preempted
);
799 if (cfqq
== cfqd
->active_queue
)
800 cfqd
->active_queue
= NULL
;
802 if (cfqd
->active_cic
) {
803 put_io_context(cfqd
->active_cic
->ioc
);
804 cfqd
->active_cic
= NULL
;
807 cfqd
->dispatch_slice
= 0;
810 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, int preempted
)
812 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
815 __cfq_slice_expired(cfqd
, cfqq
, preempted
);
828 static int cfq_get_next_prio_level(struct cfq_data
*cfqd
)
837 for (p
= cfqd
->cur_prio
; p
<= cfqd
->cur_end_prio
; p
++) {
838 if (!list_empty(&cfqd
->rr_list
[p
])) {
847 if (++cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
848 cfqd
->cur_end_prio
= 0;
855 if (unlikely(prio
== -1))
858 BUG_ON(prio
>= CFQ_PRIO_LISTS
);
860 list_splice_init(&cfqd
->rr_list
[prio
], &cfqd
->cur_rr
);
862 cfqd
->cur_prio
= prio
+ 1;
863 if (cfqd
->cur_prio
> cfqd
->cur_end_prio
) {
864 cfqd
->cur_end_prio
= cfqd
->cur_prio
;
867 if (cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
869 cfqd
->cur_end_prio
= 0;
875 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
)
877 struct cfq_queue
*cfqq
= NULL
;
880 * if current list is non-empty, grab first entry. if it is empty,
881 * get next prio level and grab first entry then if any are spliced
883 if (!list_empty(&cfqd
->cur_rr
) || cfq_get_next_prio_level(cfqd
) != -1)
884 cfqq
= list_entry_cfqq(cfqd
->cur_rr
.next
);
887 * If no new queues are available, check if the busy list has some
888 * before falling back to idle io.
890 if (!cfqq
&& !list_empty(&cfqd
->busy_rr
))
891 cfqq
= list_entry_cfqq(cfqd
->busy_rr
.next
);
894 * if we have idle queues and no rt or be queues had pending
895 * requests, either allow immediate service if the grace period
896 * has passed or arm the idle grace timer
898 if (!cfqq
&& !list_empty(&cfqd
->idle_rr
)) {
899 unsigned long end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
901 if (time_after_eq(jiffies
, end
))
902 cfqq
= list_entry_cfqq(cfqd
->idle_rr
.next
);
904 mod_timer(&cfqd
->idle_class_timer
, end
);
907 __cfq_set_active_queue(cfqd
, cfqq
);
911 static int cfq_arm_slice_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
914 struct cfq_io_context
*cic
;
917 WARN_ON(!RB_EMPTY(&cfqq
->sort_list
));
918 WARN_ON(cfqq
!= cfqd
->active_queue
);
921 * idle is disabled, either manually or by past process history
923 if (!cfqd
->cfq_slice_idle
)
925 if (!cfq_cfqq_idle_window(cfqq
))
928 * task has exited, don't wait
930 cic
= cfqd
->active_cic
;
931 if (!cic
|| !cic
->ioc
->task
)
934 cfq_mark_cfqq_must_dispatch(cfqq
);
935 cfq_mark_cfqq_wait_request(cfqq
);
937 sl
= min(cfqq
->slice_end
- 1, (unsigned long) cfqd
->cfq_slice_idle
);
940 * we don't want to idle for seeks, but we do want to allow
941 * fair distribution of slice time for a process doing back-to-back
942 * seeks. so allow a little bit of time for him to submit a new rq
944 if (sample_valid(cic
->seek_samples
) && cic
->seek_mean
> 131072)
947 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
951 static void cfq_dispatch_insert(request_queue_t
*q
, struct cfq_rq
*crq
)
953 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
954 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
956 cfqq
->next_crq
= cfq_find_next_crq(cfqd
, cfqq
, crq
);
957 cfq_remove_request(crq
->request
);
958 cfqq
->on_dispatch
[cfq_crq_is_sync(crq
)]++;
959 elv_dispatch_sort(q
, crq
->request
);
963 * return expired entry, or NULL to just start from scratch in rbtree
965 static inline struct cfq_rq
*cfq_check_fifo(struct cfq_queue
*cfqq
)
967 struct cfq_data
*cfqd
= cfqq
->cfqd
;
971 if (cfq_cfqq_fifo_expire(cfqq
))
974 if (!list_empty(&cfqq
->fifo
)) {
975 int fifo
= cfq_cfqq_class_sync(cfqq
);
977 crq
= RQ_DATA(list_entry_fifo(cfqq
->fifo
.next
));
979 if (time_after(jiffies
, rq
->start_time
+ cfqd
->cfq_fifo_expire
[fifo
])) {
980 cfq_mark_cfqq_fifo_expire(cfqq
);
989 * Scale schedule slice based on io priority. Use the sync time slice only
990 * if a queue is marked sync and has sync io queued. A sync queue with async
991 * io only, should not get full sync slice length.
994 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
996 const int base_slice
= cfqd
->cfq_slice
[cfq_cfqq_sync(cfqq
)];
998 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1000 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - cfqq
->ioprio
));
1004 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1006 cfqq
->slice_end
= cfq_prio_to_slice(cfqd
, cfqq
) + jiffies
;
1010 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1012 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1014 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1016 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1020 * get next queue for service
1022 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
1024 unsigned long now
= jiffies
;
1025 struct cfq_queue
*cfqq
;
1027 cfqq
= cfqd
->active_queue
;
1034 if (!cfq_cfqq_must_dispatch(cfqq
) && time_after(now
, cfqq
->slice_end
))
1038 * if queue has requests, dispatch one. if not, check if
1039 * enough slice is left to wait for one
1041 if (!RB_EMPTY(&cfqq
->sort_list
))
1043 else if (cfq_cfqq_class_sync(cfqq
) &&
1044 time_before(now
, cfqq
->slice_end
)) {
1045 if (cfq_arm_slice_timer(cfqd
, cfqq
))
1050 cfq_slice_expired(cfqd
, 0);
1052 cfqq
= cfq_set_active_queue(cfqd
);
1058 __cfq_dispatch_requests(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1063 BUG_ON(RB_EMPTY(&cfqq
->sort_list
));
1069 * follow expired path, else get first next available
1071 if ((crq
= cfq_check_fifo(cfqq
)) == NULL
)
1072 crq
= cfqq
->next_crq
;
1075 * finally, insert request into driver dispatch list
1077 cfq_dispatch_insert(cfqd
->queue
, crq
);
1079 cfqd
->dispatch_slice
++;
1082 if (!cfqd
->active_cic
) {
1083 atomic_inc(&crq
->io_context
->ioc
->refcount
);
1084 cfqd
->active_cic
= crq
->io_context
;
1087 if (RB_EMPTY(&cfqq
->sort_list
))
1090 } while (dispatched
< max_dispatch
);
1093 * if slice end isn't set yet, set it. if at least one request was
1094 * sync, use the sync time slice value
1096 if (!cfqq
->slice_end
)
1097 cfq_set_prio_slice(cfqd
, cfqq
);
1100 * expire an async queue immediately if it has used up its slice. idle
1101 * queue always expire after 1 dispatch round.
1103 if ((!cfq_cfqq_sync(cfqq
) &&
1104 cfqd
->dispatch_slice
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1105 cfq_class_idle(cfqq
))
1106 cfq_slice_expired(cfqd
, 0);
1112 cfq_forced_dispatch_cfqqs(struct list_head
*list
)
1115 struct cfq_queue
*cfqq
, *next
;
1118 list_for_each_entry_safe(cfqq
, next
, list
, cfq_list
) {
1119 while ((crq
= cfqq
->next_crq
)) {
1120 cfq_dispatch_insert(cfqq
->cfqd
->queue
, crq
);
1123 BUG_ON(!list_empty(&cfqq
->fifo
));
1129 cfq_forced_dispatch(struct cfq_data
*cfqd
)
1131 int i
, dispatched
= 0;
1133 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
1134 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->rr_list
[i
]);
1136 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->busy_rr
);
1137 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->cur_rr
);
1138 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->idle_rr
);
1140 cfq_slice_expired(cfqd
, 0);
1142 BUG_ON(cfqd
->busy_queues
);
1148 cfq_dispatch_requests(request_queue_t
*q
, int force
)
1150 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1151 struct cfq_queue
*cfqq
;
1153 if (!cfqd
->busy_queues
)
1156 if (unlikely(force
))
1157 return cfq_forced_dispatch(cfqd
);
1159 cfqq
= cfq_select_queue(cfqd
);
1163 cfq_clear_cfqq_must_dispatch(cfqq
);
1164 cfq_clear_cfqq_wait_request(cfqq
);
1165 del_timer(&cfqd
->idle_slice_timer
);
1167 max_dispatch
= cfqd
->cfq_quantum
;
1168 if (cfq_class_idle(cfqq
))
1171 return __cfq_dispatch_requests(cfqd
, cfqq
, max_dispatch
);
1178 * task holds one reference to the queue, dropped when task exits. each crq
1179 * in-flight on this queue also holds a reference, dropped when crq is freed.
1181 * queue lock must be held here.
1183 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1185 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1187 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1189 if (!atomic_dec_and_test(&cfqq
->ref
))
1192 BUG_ON(rb_first(&cfqq
->sort_list
));
1193 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1194 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1196 if (unlikely(cfqd
->active_queue
== cfqq
))
1197 __cfq_slice_expired(cfqd
, cfqq
, 0);
1200 * it's on the empty list and still hashed
1202 list_del(&cfqq
->cfq_list
);
1203 hlist_del(&cfqq
->cfq_hash
);
1204 kmem_cache_free(cfq_pool
, cfqq
);
1207 static inline struct cfq_queue
*
1208 __cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned int prio
,
1211 struct hlist_head
*hash_list
= &cfqd
->cfq_hash
[hashval
];
1212 struct hlist_node
*entry
;
1213 struct cfq_queue
*__cfqq
;
1215 hlist_for_each_entry(__cfqq
, entry
, hash_list
, cfq_hash
) {
1216 const unsigned short __p
= IOPRIO_PRIO_VALUE(__cfqq
->org_ioprio_class
, __cfqq
->org_ioprio
);
1218 if (__cfqq
->key
== key
&& (__p
== prio
|| !prio
))
1225 static struct cfq_queue
*
1226 cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned short prio
)
1228 return __cfq_find_cfq_hash(cfqd
, key
, prio
, hash_long(key
, CFQ_QHASH_SHIFT
));
1231 static void cfq_free_io_context(struct io_context
*ioc
)
1233 struct cfq_io_context
*__cic
;
1237 while ((n
= rb_first(&ioc
->cic_root
)) != NULL
) {
1238 __cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1239 rb_erase(&__cic
->rb_node
, &ioc
->cic_root
);
1240 kmem_cache_free(cfq_ioc_pool
, __cic
);
1244 if (atomic_sub_and_test(freed
, &ioc_count
) && ioc_gone
)
1248 static void cfq_trim(struct io_context
*ioc
)
1250 ioc
->set_ioprio
= NULL
;
1251 cfq_free_io_context(ioc
);
1255 * Called with interrupts disabled
1257 static void cfq_exit_single_io_context(struct cfq_io_context
*cic
)
1259 struct cfq_data
*cfqd
= cic
->key
;
1267 WARN_ON(!irqs_disabled());
1269 spin_lock(q
->queue_lock
);
1271 if (cic
->cfqq
[ASYNC
]) {
1272 if (unlikely(cic
->cfqq
[ASYNC
] == cfqd
->active_queue
))
1273 __cfq_slice_expired(cfqd
, cic
->cfqq
[ASYNC
], 0);
1274 cfq_put_queue(cic
->cfqq
[ASYNC
]);
1275 cic
->cfqq
[ASYNC
] = NULL
;
1278 if (cic
->cfqq
[SYNC
]) {
1279 if (unlikely(cic
->cfqq
[SYNC
] == cfqd
->active_queue
))
1280 __cfq_slice_expired(cfqd
, cic
->cfqq
[SYNC
], 0);
1281 cfq_put_queue(cic
->cfqq
[SYNC
]);
1282 cic
->cfqq
[SYNC
] = NULL
;
1286 list_del_init(&cic
->queue_list
);
1287 spin_unlock(q
->queue_lock
);
1290 static void cfq_exit_io_context(struct io_context
*ioc
)
1292 struct cfq_io_context
*__cic
;
1293 unsigned long flags
;
1297 * put the reference this task is holding to the various queues
1299 spin_lock_irqsave(&cfq_exit_lock
, flags
);
1301 n
= rb_first(&ioc
->cic_root
);
1303 __cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1305 cfq_exit_single_io_context(__cic
);
1309 spin_unlock_irqrestore(&cfq_exit_lock
, flags
);
1312 static struct cfq_io_context
*
1313 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1315 struct cfq_io_context
*cic
= kmem_cache_alloc(cfq_ioc_pool
, gfp_mask
);
1318 memset(cic
, 0, sizeof(*cic
));
1319 cic
->last_end_request
= jiffies
;
1320 INIT_LIST_HEAD(&cic
->queue_list
);
1321 cic
->dtor
= cfq_free_io_context
;
1322 cic
->exit
= cfq_exit_io_context
;
1323 atomic_inc(&ioc_count
);
1329 static void cfq_init_prio_data(struct cfq_queue
*cfqq
)
1331 struct task_struct
*tsk
= current
;
1334 if (!cfq_cfqq_prio_changed(cfqq
))
1337 ioprio_class
= IOPRIO_PRIO_CLASS(tsk
->ioprio
);
1338 switch (ioprio_class
) {
1340 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1341 case IOPRIO_CLASS_NONE
:
1343 * no prio set, place us in the middle of the BE classes
1345 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1346 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1348 case IOPRIO_CLASS_RT
:
1349 cfqq
->ioprio
= task_ioprio(tsk
);
1350 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1352 case IOPRIO_CLASS_BE
:
1353 cfqq
->ioprio
= task_ioprio(tsk
);
1354 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1356 case IOPRIO_CLASS_IDLE
:
1357 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
1359 cfq_clear_cfqq_idle_window(cfqq
);
1364 * keep track of original prio settings in case we have to temporarily
1365 * elevate the priority of this queue
1367 cfqq
->org_ioprio
= cfqq
->ioprio
;
1368 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
1370 if (cfq_cfqq_on_rr(cfqq
))
1371 cfq_resort_rr_list(cfqq
, 0);
1373 cfq_clear_cfqq_prio_changed(cfqq
);
1376 static inline void changed_ioprio(struct cfq_io_context
*cic
)
1378 struct cfq_data
*cfqd
= cic
->key
;
1379 struct cfq_queue
*cfqq
;
1381 spin_lock(cfqd
->queue
->queue_lock
);
1382 cfqq
= cic
->cfqq
[ASYNC
];
1384 struct cfq_queue
*new_cfqq
;
1385 new_cfqq
= cfq_get_queue(cfqd
, CFQ_KEY_ASYNC
,
1386 cic
->ioc
->task
, GFP_ATOMIC
);
1388 cic
->cfqq
[ASYNC
] = new_cfqq
;
1389 cfq_put_queue(cfqq
);
1392 cfqq
= cic
->cfqq
[SYNC
];
1394 cfq_mark_cfqq_prio_changed(cfqq
);
1395 cfq_init_prio_data(cfqq
);
1397 spin_unlock(cfqd
->queue
->queue_lock
);
1402 * callback from sys_ioprio_set, irqs are disabled
1404 static int cfq_ioc_set_ioprio(struct io_context
*ioc
, unsigned int ioprio
)
1406 struct cfq_io_context
*cic
;
1409 spin_lock(&cfq_exit_lock
);
1411 n
= rb_first(&ioc
->cic_root
);
1413 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1415 changed_ioprio(cic
);
1419 spin_unlock(&cfq_exit_lock
);
1424 static struct cfq_queue
*
1425 cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, struct task_struct
*tsk
,
1428 const int hashval
= hash_long(key
, CFQ_QHASH_SHIFT
);
1429 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1430 unsigned short ioprio
;
1433 ioprio
= tsk
->ioprio
;
1434 cfqq
= __cfq_find_cfq_hash(cfqd
, key
, ioprio
, hashval
);
1440 } else if (gfp_mask
& __GFP_WAIT
) {
1441 spin_unlock_irq(cfqd
->queue
->queue_lock
);
1442 new_cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1443 spin_lock_irq(cfqd
->queue
->queue_lock
);
1446 cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1451 memset(cfqq
, 0, sizeof(*cfqq
));
1453 INIT_HLIST_NODE(&cfqq
->cfq_hash
);
1454 INIT_LIST_HEAD(&cfqq
->cfq_list
);
1455 RB_CLEAR_ROOT(&cfqq
->sort_list
);
1456 INIT_LIST_HEAD(&cfqq
->fifo
);
1459 hlist_add_head(&cfqq
->cfq_hash
, &cfqd
->cfq_hash
[hashval
]);
1460 atomic_set(&cfqq
->ref
, 0);
1462 cfqq
->service_last
= 0;
1464 * set ->slice_left to allow preemption for a new process
1466 cfqq
->slice_left
= 2 * cfqd
->cfq_slice_idle
;
1468 cfq_mark_cfqq_idle_window(cfqq
);
1469 cfq_mark_cfqq_prio_changed(cfqq
);
1470 cfq_init_prio_data(cfqq
);
1474 kmem_cache_free(cfq_pool
, new_cfqq
);
1476 atomic_inc(&cfqq
->ref
);
1478 WARN_ON((gfp_mask
& __GFP_WAIT
) && !cfqq
);
1483 cfq_drop_dead_cic(struct io_context
*ioc
, struct cfq_io_context
*cic
)
1485 spin_lock(&cfq_exit_lock
);
1486 rb_erase(&cic
->rb_node
, &ioc
->cic_root
);
1487 list_del_init(&cic
->queue_list
);
1488 spin_unlock(&cfq_exit_lock
);
1489 kmem_cache_free(cfq_ioc_pool
, cic
);
1490 atomic_dec(&ioc_count
);
1493 static struct cfq_io_context
*
1494 cfq_cic_rb_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
1497 struct cfq_io_context
*cic
;
1498 void *k
, *key
= cfqd
;
1501 n
= ioc
->cic_root
.rb_node
;
1503 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1504 /* ->key must be copied to avoid race with cfq_exit_queue() */
1507 cfq_drop_dead_cic(ioc
, cic
);
1523 cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
1524 struct cfq_io_context
*cic
)
1527 struct rb_node
*parent
;
1528 struct cfq_io_context
*__cic
;
1534 ioc
->set_ioprio
= cfq_ioc_set_ioprio
;
1537 p
= &ioc
->cic_root
.rb_node
;
1540 __cic
= rb_entry(parent
, struct cfq_io_context
, rb_node
);
1541 /* ->key must be copied to avoid race with cfq_exit_queue() */
1544 cfq_drop_dead_cic(ioc
, cic
);
1550 else if (cic
->key
> k
)
1551 p
= &(*p
)->rb_right
;
1556 spin_lock(&cfq_exit_lock
);
1557 rb_link_node(&cic
->rb_node
, parent
, p
);
1558 rb_insert_color(&cic
->rb_node
, &ioc
->cic_root
);
1559 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
1560 spin_unlock(&cfq_exit_lock
);
1564 * Setup general io context and cfq io context. There can be several cfq
1565 * io contexts per general io context, if this process is doing io to more
1566 * than one device managed by cfq.
1568 static struct cfq_io_context
*
1569 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1571 struct io_context
*ioc
= NULL
;
1572 struct cfq_io_context
*cic
;
1574 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1576 ioc
= get_io_context(gfp_mask
);
1580 cic
= cfq_cic_rb_lookup(cfqd
, ioc
);
1584 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1588 cfq_cic_link(cfqd
, ioc
, cic
);
1592 put_io_context(ioc
);
1597 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
1599 unsigned long elapsed
, ttime
;
1602 * if this context already has stuff queued, thinktime is from
1603 * last queue not last end
1606 if (time_after(cic
->last_end_request
, cic
->last_queue
))
1607 elapsed
= jiffies
- cic
->last_end_request
;
1609 elapsed
= jiffies
- cic
->last_queue
;
1611 elapsed
= jiffies
- cic
->last_end_request
;
1614 ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
1616 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
1617 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
1618 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
1622 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
1628 if (cic
->last_request_pos
< crq
->request
->sector
)
1629 sdist
= crq
->request
->sector
- cic
->last_request_pos
;
1631 sdist
= cic
->last_request_pos
- crq
->request
->sector
;
1634 * Don't allow the seek distance to get too large from the
1635 * odd fragment, pagein, etc
1637 if (cic
->seek_samples
<= 60) /* second&third seek */
1638 sdist
= min(sdist
, (cic
->seek_mean
* 4) + 2*1024*1024);
1640 sdist
= min(sdist
, (cic
->seek_mean
* 4) + 2*1024*64);
1642 cic
->seek_samples
= (7*cic
->seek_samples
+ 256) / 8;
1643 cic
->seek_total
= (7*cic
->seek_total
+ (u64
)256*sdist
) / 8;
1644 total
= cic
->seek_total
+ (cic
->seek_samples
/2);
1645 do_div(total
, cic
->seek_samples
);
1646 cic
->seek_mean
= (sector_t
)total
;
1650 * Disable idle window if the process thinks too long or seeks so much that
1654 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1655 struct cfq_io_context
*cic
)
1657 int enable_idle
= cfq_cfqq_idle_window(cfqq
);
1659 if (!cic
->ioc
->task
|| !cfqd
->cfq_slice_idle
|| cfqd
->hw_tag
)
1661 else if (sample_valid(cic
->ttime_samples
)) {
1662 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
1669 cfq_mark_cfqq_idle_window(cfqq
);
1671 cfq_clear_cfqq_idle_window(cfqq
);
1676 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1677 * no or if we aren't sure, a 1 will cause a preempt.
1680 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
1683 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1685 if (cfq_class_idle(new_cfqq
))
1691 if (cfq_class_idle(cfqq
))
1693 if (!cfq_cfqq_wait_request(new_cfqq
))
1696 * if it doesn't have slice left, forget it
1698 if (new_cfqq
->slice_left
< cfqd
->cfq_slice_idle
)
1700 if (cfq_crq_is_sync(crq
) && !cfq_cfqq_sync(cfqq
))
1707 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1708 * let it have half of its nominal slice.
1710 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1712 struct cfq_queue
*__cfqq
, *next
;
1714 list_for_each_entry_safe(__cfqq
, next
, &cfqd
->cur_rr
, cfq_list
)
1715 cfq_resort_rr_list(__cfqq
, 1);
1717 if (!cfqq
->slice_left
)
1718 cfqq
->slice_left
= cfq_prio_to_slice(cfqd
, cfqq
) / 2;
1720 cfqq
->slice_end
= cfqq
->slice_left
+ jiffies
;
1721 __cfq_slice_expired(cfqd
, cfqq
, 1);
1722 __cfq_set_active_queue(cfqd
, cfqq
);
1726 * should really be a ll_rw_blk.c helper
1728 static void cfq_start_queueing(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1730 request_queue_t
*q
= cfqd
->queue
;
1732 if (!blk_queue_plugged(q
))
1735 __generic_unplug_device(q
);
1739 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1740 * something we should do about it
1743 cfq_crq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1746 struct cfq_io_context
*cic
;
1748 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
1750 cic
= crq
->io_context
;
1753 * we never wait for an async request and we don't allow preemption
1754 * of an async request. so just return early
1756 if (!cfq_crq_is_sync(crq
)) {
1758 * sync process issued an async request, if it's waiting
1759 * then expire it and kick rq handling.
1761 if (cic
== cfqd
->active_cic
&&
1762 del_timer(&cfqd
->idle_slice_timer
)) {
1763 cfq_slice_expired(cfqd
, 0);
1764 cfq_start_queueing(cfqd
, cfqq
);
1769 cfq_update_io_thinktime(cfqd
, cic
);
1770 cfq_update_io_seektime(cfqd
, cic
, crq
);
1771 cfq_update_idle_window(cfqd
, cfqq
, cic
);
1773 cic
->last_queue
= jiffies
;
1774 cic
->last_request_pos
= crq
->request
->sector
+ crq
->request
->nr_sectors
;
1776 if (cfqq
== cfqd
->active_queue
) {
1778 * if we are waiting for a request for this queue, let it rip
1779 * immediately and flag that we must not expire this queue
1782 if (cfq_cfqq_wait_request(cfqq
)) {
1783 cfq_mark_cfqq_must_dispatch(cfqq
);
1784 del_timer(&cfqd
->idle_slice_timer
);
1785 cfq_start_queueing(cfqd
, cfqq
);
1787 } else if (cfq_should_preempt(cfqd
, cfqq
, crq
)) {
1789 * not the active queue - expire current slice if it is
1790 * idle and has expired it's mean thinktime or this new queue
1791 * has some old slice time left and is of higher priority
1793 cfq_preempt_queue(cfqd
, cfqq
);
1794 cfq_mark_cfqq_must_dispatch(cfqq
);
1795 cfq_start_queueing(cfqd
, cfqq
);
1799 static void cfq_insert_request(request_queue_t
*q
, struct request
*rq
)
1801 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1802 struct cfq_rq
*crq
= RQ_DATA(rq
);
1803 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1805 cfq_init_prio_data(cfqq
);
1807 cfq_add_crq_rb(crq
);
1809 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
1811 if (rq_mergeable(rq
))
1812 cfq_add_crq_hash(cfqd
, crq
);
1814 cfq_crq_enqueued(cfqd
, cfqq
, crq
);
1817 static void cfq_completed_request(request_queue_t
*q
, struct request
*rq
)
1819 struct cfq_rq
*crq
= RQ_DATA(rq
);
1820 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1821 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1822 const int sync
= cfq_crq_is_sync(crq
);
1827 WARN_ON(!cfqd
->rq_in_driver
);
1828 WARN_ON(!cfqq
->on_dispatch
[sync
]);
1829 cfqd
->rq_in_driver
--;
1830 cfqq
->on_dispatch
[sync
]--;
1832 if (!cfq_class_idle(cfqq
))
1833 cfqd
->last_end_request
= now
;
1835 if (!cfq_cfqq_dispatched(cfqq
)) {
1836 if (cfq_cfqq_on_rr(cfqq
)) {
1837 cfqq
->service_last
= now
;
1838 cfq_resort_rr_list(cfqq
, 0);
1840 cfq_schedule_dispatch(cfqd
);
1843 if (cfq_crq_is_sync(crq
))
1844 crq
->io_context
->last_end_request
= now
;
1847 static struct request
*
1848 cfq_former_request(request_queue_t
*q
, struct request
*rq
)
1850 struct cfq_rq
*crq
= RQ_DATA(rq
);
1851 struct rb_node
*rbprev
= rb_prev(&crq
->rb_node
);
1854 return rb_entry_crq(rbprev
)->request
;
1859 static struct request
*
1860 cfq_latter_request(request_queue_t
*q
, struct request
*rq
)
1862 struct cfq_rq
*crq
= RQ_DATA(rq
);
1863 struct rb_node
*rbnext
= rb_next(&crq
->rb_node
);
1866 return rb_entry_crq(rbnext
)->request
;
1872 * we temporarily boost lower priority queues if they are holding fs exclusive
1873 * resources. they are boosted to normal prio (CLASS_BE/4)
1875 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
1877 const int ioprio_class
= cfqq
->ioprio_class
;
1878 const int ioprio
= cfqq
->ioprio
;
1880 if (has_fs_excl()) {
1882 * boost idle prio on transactions that would lock out other
1883 * users of the filesystem
1885 if (cfq_class_idle(cfqq
))
1886 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1887 if (cfqq
->ioprio
> IOPRIO_NORM
)
1888 cfqq
->ioprio
= IOPRIO_NORM
;
1891 * check if we need to unboost the queue
1893 if (cfqq
->ioprio_class
!= cfqq
->org_ioprio_class
)
1894 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
1895 if (cfqq
->ioprio
!= cfqq
->org_ioprio
)
1896 cfqq
->ioprio
= cfqq
->org_ioprio
;
1900 * refile between round-robin lists if we moved the priority class
1902 if ((ioprio_class
!= cfqq
->ioprio_class
|| ioprio
!= cfqq
->ioprio
) &&
1903 cfq_cfqq_on_rr(cfqq
))
1904 cfq_resort_rr_list(cfqq
, 0);
1908 __cfq_may_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1909 struct task_struct
*task
, int rw
)
1911 if ((cfq_cfqq_wait_request(cfqq
) || cfq_cfqq_must_alloc(cfqq
)) &&
1912 !cfq_cfqq_must_alloc_slice(cfqq
)) {
1913 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1914 return ELV_MQUEUE_MUST
;
1917 return ELV_MQUEUE_MAY
;
1920 static int cfq_may_queue(request_queue_t
*q
, int rw
, struct bio
*bio
)
1922 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1923 struct task_struct
*tsk
= current
;
1924 struct cfq_queue
*cfqq
;
1927 * don't force setup of a queue from here, as a call to may_queue
1928 * does not necessarily imply that a request actually will be queued.
1929 * so just lookup a possibly existing queue, or return 'may queue'
1932 cfqq
= cfq_find_cfq_hash(cfqd
, cfq_queue_pid(tsk
, rw
), tsk
->ioprio
);
1934 cfq_init_prio_data(cfqq
);
1935 cfq_prio_boost(cfqq
);
1937 return __cfq_may_queue(cfqd
, cfqq
, tsk
, rw
);
1940 return ELV_MQUEUE_MAY
;
1943 static void cfq_check_waiters(request_queue_t
*q
, struct cfq_queue
*cfqq
)
1945 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1947 if (unlikely(cfqd
->rq_starved
)) {
1948 struct request_list
*rl
= &q
->rq
;
1951 if (waitqueue_active(&rl
->wait
[READ
]))
1952 wake_up(&rl
->wait
[READ
]);
1953 if (waitqueue_active(&rl
->wait
[WRITE
]))
1954 wake_up(&rl
->wait
[WRITE
]);
1959 * queue lock held here
1961 static void cfq_put_request(request_queue_t
*q
, struct request
*rq
)
1963 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1964 struct cfq_rq
*crq
= RQ_DATA(rq
);
1967 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1968 const int rw
= rq_data_dir(rq
);
1970 BUG_ON(!cfqq
->allocated
[rw
]);
1971 cfqq
->allocated
[rw
]--;
1973 put_io_context(crq
->io_context
->ioc
);
1975 mempool_free(crq
, cfqd
->crq_pool
);
1976 rq
->elevator_private
= NULL
;
1978 cfq_check_waiters(q
, cfqq
);
1979 cfq_put_queue(cfqq
);
1984 * Allocate cfq data structures associated with this request.
1987 cfq_set_request(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
,
1990 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1991 struct task_struct
*tsk
= current
;
1992 struct cfq_io_context
*cic
;
1993 const int rw
= rq_data_dir(rq
);
1994 pid_t key
= cfq_queue_pid(tsk
, rw
);
1995 struct cfq_queue
*cfqq
;
1997 unsigned long flags
;
1998 int is_sync
= key
!= CFQ_KEY_ASYNC
;
2000 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2002 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
2004 spin_lock_irqsave(q
->queue_lock
, flags
);
2009 if (!cic
->cfqq
[is_sync
]) {
2010 cfqq
= cfq_get_queue(cfqd
, key
, tsk
, gfp_mask
);
2014 cic
->cfqq
[is_sync
] = cfqq
;
2016 cfqq
= cic
->cfqq
[is_sync
];
2018 cfqq
->allocated
[rw
]++;
2019 cfq_clear_cfqq_must_alloc(cfqq
);
2020 cfqd
->rq_starved
= 0;
2021 atomic_inc(&cfqq
->ref
);
2022 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2024 crq
= mempool_alloc(cfqd
->crq_pool
, gfp_mask
);
2026 RB_CLEAR(&crq
->rb_node
);
2029 INIT_HLIST_NODE(&crq
->hash
);
2030 crq
->cfq_queue
= cfqq
;
2031 crq
->io_context
= cic
;
2034 cfq_mark_crq_is_sync(crq
);
2036 cfq_clear_crq_is_sync(crq
);
2038 rq
->elevator_private
= crq
;
2042 spin_lock_irqsave(q
->queue_lock
, flags
);
2043 cfqq
->allocated
[rw
]--;
2044 if (!(cfqq
->allocated
[0] + cfqq
->allocated
[1]))
2045 cfq_mark_cfqq_must_alloc(cfqq
);
2046 cfq_put_queue(cfqq
);
2049 put_io_context(cic
->ioc
);
2051 * mark us rq allocation starved. we need to kickstart the process
2052 * ourselves if there are no pending requests that can do it for us.
2053 * that would be an extremely rare OOM situation
2055 cfqd
->rq_starved
= 1;
2056 cfq_schedule_dispatch(cfqd
);
2057 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2061 static void cfq_kick_queue(void *data
)
2063 request_queue_t
*q
= data
;
2064 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2065 unsigned long flags
;
2067 spin_lock_irqsave(q
->queue_lock
, flags
);
2069 if (cfqd
->rq_starved
) {
2070 struct request_list
*rl
= &q
->rq
;
2073 * we aren't guaranteed to get a request after this, but we
2074 * have to be opportunistic
2077 if (waitqueue_active(&rl
->wait
[READ
]))
2078 wake_up(&rl
->wait
[READ
]);
2079 if (waitqueue_active(&rl
->wait
[WRITE
]))
2080 wake_up(&rl
->wait
[WRITE
]);
2085 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2089 * Timer running if the active_queue is currently idling inside its time slice
2091 static void cfq_idle_slice_timer(unsigned long data
)
2093 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2094 struct cfq_queue
*cfqq
;
2095 unsigned long flags
;
2097 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2099 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
2100 unsigned long now
= jiffies
;
2105 if (time_after(now
, cfqq
->slice_end
))
2109 * only expire and reinvoke request handler, if there are
2110 * other queues with pending requests
2112 if (!cfqd
->busy_queues
) {
2113 cfqd
->idle_slice_timer
.expires
= min(now
+ cfqd
->cfq_slice_idle
, cfqq
->slice_end
);
2114 add_timer(&cfqd
->idle_slice_timer
);
2119 * not expired and it has a request pending, let it dispatch
2121 if (!RB_EMPTY(&cfqq
->sort_list
)) {
2122 cfq_mark_cfqq_must_dispatch(cfqq
);
2127 cfq_slice_expired(cfqd
, 0);
2129 cfq_schedule_dispatch(cfqd
);
2131 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2135 * Timer running if an idle class queue is waiting for service
2137 static void cfq_idle_class_timer(unsigned long data
)
2139 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2140 unsigned long flags
, end
;
2142 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2145 * race with a non-idle queue, reset timer
2147 end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
2148 if (!time_after_eq(jiffies
, end
))
2149 mod_timer(&cfqd
->idle_class_timer
, end
);
2151 cfq_schedule_dispatch(cfqd
);
2153 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2156 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2158 del_timer_sync(&cfqd
->idle_slice_timer
);
2159 del_timer_sync(&cfqd
->idle_class_timer
);
2160 blk_sync_queue(cfqd
->queue
);
2163 static void cfq_exit_queue(elevator_t
*e
)
2165 struct cfq_data
*cfqd
= e
->elevator_data
;
2166 request_queue_t
*q
= cfqd
->queue
;
2168 cfq_shutdown_timer_wq(cfqd
);
2170 spin_lock(&cfq_exit_lock
);
2171 spin_lock_irq(q
->queue_lock
);
2173 if (cfqd
->active_queue
)
2174 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
2176 while (!list_empty(&cfqd
->cic_list
)) {
2177 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
2178 struct cfq_io_context
,
2180 if (cic
->cfqq
[ASYNC
]) {
2181 cfq_put_queue(cic
->cfqq
[ASYNC
]);
2182 cic
->cfqq
[ASYNC
] = NULL
;
2184 if (cic
->cfqq
[SYNC
]) {
2185 cfq_put_queue(cic
->cfqq
[SYNC
]);
2186 cic
->cfqq
[SYNC
] = NULL
;
2189 list_del_init(&cic
->queue_list
);
2192 spin_unlock_irq(q
->queue_lock
);
2193 spin_unlock(&cfq_exit_lock
);
2195 cfq_shutdown_timer_wq(cfqd
);
2197 mempool_destroy(cfqd
->crq_pool
);
2198 kfree(cfqd
->crq_hash
);
2199 kfree(cfqd
->cfq_hash
);
2203 static void *cfq_init_queue(request_queue_t
*q
, elevator_t
*e
)
2205 struct cfq_data
*cfqd
;
2208 cfqd
= kmalloc(sizeof(*cfqd
), GFP_KERNEL
);
2212 memset(cfqd
, 0, sizeof(*cfqd
));
2214 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2215 INIT_LIST_HEAD(&cfqd
->rr_list
[i
]);
2217 INIT_LIST_HEAD(&cfqd
->busy_rr
);
2218 INIT_LIST_HEAD(&cfqd
->cur_rr
);
2219 INIT_LIST_HEAD(&cfqd
->idle_rr
);
2220 INIT_LIST_HEAD(&cfqd
->empty_list
);
2221 INIT_LIST_HEAD(&cfqd
->cic_list
);
2223 cfqd
->crq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_MHASH_ENTRIES
, GFP_KERNEL
);
2224 if (!cfqd
->crq_hash
)
2227 cfqd
->cfq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_QHASH_ENTRIES
, GFP_KERNEL
);
2228 if (!cfqd
->cfq_hash
)
2231 cfqd
->crq_pool
= mempool_create_slab_pool(BLKDEV_MIN_RQ
, crq_pool
);
2232 if (!cfqd
->crq_pool
)
2235 for (i
= 0; i
< CFQ_MHASH_ENTRIES
; i
++)
2236 INIT_HLIST_HEAD(&cfqd
->crq_hash
[i
]);
2237 for (i
= 0; i
< CFQ_QHASH_ENTRIES
; i
++)
2238 INIT_HLIST_HEAD(&cfqd
->cfq_hash
[i
]);
2242 init_timer(&cfqd
->idle_slice_timer
);
2243 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
2244 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
2246 init_timer(&cfqd
->idle_class_timer
);
2247 cfqd
->idle_class_timer
.function
= cfq_idle_class_timer
;
2248 cfqd
->idle_class_timer
.data
= (unsigned long) cfqd
;
2250 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
, q
);
2252 cfqd
->cfq_queued
= cfq_queued
;
2253 cfqd
->cfq_quantum
= cfq_quantum
;
2254 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
2255 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
2256 cfqd
->cfq_back_max
= cfq_back_max
;
2257 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
2258 cfqd
->cfq_slice
[0] = cfq_slice_async
;
2259 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
2260 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
2261 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
2265 kfree(cfqd
->cfq_hash
);
2267 kfree(cfqd
->crq_hash
);
2273 static void cfq_slab_kill(void)
2276 kmem_cache_destroy(crq_pool
);
2278 kmem_cache_destroy(cfq_pool
);
2280 kmem_cache_destroy(cfq_ioc_pool
);
2283 static int __init
cfq_slab_setup(void)
2285 crq_pool
= kmem_cache_create("crq_pool", sizeof(struct cfq_rq
), 0, 0,
2290 cfq_pool
= kmem_cache_create("cfq_pool", sizeof(struct cfq_queue
), 0, 0,
2295 cfq_ioc_pool
= kmem_cache_create("cfq_ioc_pool",
2296 sizeof(struct cfq_io_context
), 0, 0, NULL
, NULL
);
2307 * sysfs parts below -->
2311 cfq_var_show(unsigned int var
, char *page
)
2313 return sprintf(page
, "%d\n", var
);
2317 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
2319 char *p
= (char *) page
;
2321 *var
= simple_strtoul(p
, &p
, 10);
2325 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2326 static ssize_t __FUNC(elevator_t *e, char *page) \
2328 struct cfq_data *cfqd = e->elevator_data; \
2329 unsigned int __data = __VAR; \
2331 __data = jiffies_to_msecs(__data); \
2332 return cfq_var_show(__data, (page)); \
2334 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
2335 SHOW_FUNCTION(cfq_queued_show
, cfqd
->cfq_queued
, 0);
2336 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
2337 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
2338 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
2339 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
2340 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
2341 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
2342 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
2343 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
2344 #undef SHOW_FUNCTION
2346 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2347 static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \
2349 struct cfq_data *cfqd = e->elevator_data; \
2350 unsigned int __data; \
2351 int ret = cfq_var_store(&__data, (page), count); \
2352 if (__data < (MIN)) \
2354 else if (__data > (MAX)) \
2357 *(__PTR) = msecs_to_jiffies(__data); \
2359 *(__PTR) = __data; \
2362 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
2363 STORE_FUNCTION(cfq_queued_store
, &cfqd
->cfq_queued
, 1, UINT_MAX
, 0);
2364 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1, UINT_MAX
, 1);
2365 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1, UINT_MAX
, 1);
2366 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
2367 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1, UINT_MAX
, 0);
2368 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
2369 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
2370 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
2371 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1, UINT_MAX
, 0);
2372 #undef STORE_FUNCTION
2374 #define CFQ_ATTR(name) \
2375 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2377 static struct elv_fs_entry cfq_attrs
[] = {
2380 CFQ_ATTR(fifo_expire_sync
),
2381 CFQ_ATTR(fifo_expire_async
),
2382 CFQ_ATTR(back_seek_max
),
2383 CFQ_ATTR(back_seek_penalty
),
2384 CFQ_ATTR(slice_sync
),
2385 CFQ_ATTR(slice_async
),
2386 CFQ_ATTR(slice_async_rq
),
2387 CFQ_ATTR(slice_idle
),
2391 static struct elevator_type iosched_cfq
= {
2393 .elevator_merge_fn
= cfq_merge
,
2394 .elevator_merged_fn
= cfq_merged_request
,
2395 .elevator_merge_req_fn
= cfq_merged_requests
,
2396 .elevator_dispatch_fn
= cfq_dispatch_requests
,
2397 .elevator_add_req_fn
= cfq_insert_request
,
2398 .elevator_activate_req_fn
= cfq_activate_request
,
2399 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
2400 .elevator_queue_empty_fn
= cfq_queue_empty
,
2401 .elevator_completed_req_fn
= cfq_completed_request
,
2402 .elevator_former_req_fn
= cfq_former_request
,
2403 .elevator_latter_req_fn
= cfq_latter_request
,
2404 .elevator_set_req_fn
= cfq_set_request
,
2405 .elevator_put_req_fn
= cfq_put_request
,
2406 .elevator_may_queue_fn
= cfq_may_queue
,
2407 .elevator_init_fn
= cfq_init_queue
,
2408 .elevator_exit_fn
= cfq_exit_queue
,
2411 .elevator_attrs
= cfq_attrs
,
2412 .elevator_name
= "cfq",
2413 .elevator_owner
= THIS_MODULE
,
2416 static int __init
cfq_init(void)
2421 * could be 0 on HZ < 1000 setups
2423 if (!cfq_slice_async
)
2424 cfq_slice_async
= 1;
2425 if (!cfq_slice_idle
)
2428 if (cfq_slab_setup())
2431 ret
= elv_register(&iosched_cfq
);
2438 static void __exit
cfq_exit(void)
2440 DECLARE_COMPLETION(all_gone
);
2441 elv_unregister(&iosched_cfq
);
2442 ioc_gone
= &all_gone
;
2443 /* ioc_gone's update must be visible before reading ioc_count */
2445 if (atomic_read(&ioc_count
))
2446 wait_for_completion(ioc_gone
);
2451 module_init(cfq_init
);
2452 module_exit(cfq_exit
);
2454 MODULE_AUTHOR("Jens Axboe");
2455 MODULE_LICENSE("GPL");
2456 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");