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/module.h>
10 #include <linux/blkdev.h>
11 #include <linux/elevator.h>
12 #include <linux/hash.h>
13 #include <linux/rbtree.h>
14 #include <linux/ioprio.h>
19 static const int cfq_quantum
= 4; /* max queue in one round of service */
20 static const int cfq_queued
= 8; /* minimum rq allocate limit per-queue*/
21 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
22 static const int cfq_back_max
= 16 * 1024; /* maximum backwards seek, in KiB */
23 static const int cfq_back_penalty
= 2; /* penalty of a backwards seek */
25 static const int cfq_slice_sync
= HZ
/ 10;
26 static int cfq_slice_async
= HZ
/ 25;
27 static const int cfq_slice_async_rq
= 2;
28 static int cfq_slice_idle
= HZ
/ 125;
30 #define CFQ_IDLE_GRACE (HZ / 10)
31 #define CFQ_SLICE_SCALE (5)
33 #define CFQ_KEY_ASYNC (0)
35 static DEFINE_SPINLOCK(cfq_exit_lock
);
38 * for the hash of cfqq inside the cfqd
40 #define CFQ_QHASH_SHIFT 6
41 #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
42 #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
44 #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
45 #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
47 #define RQ_DATA(rq) (rq)->elevator_private
52 #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
53 #define rq_rb_key(rq) (rq)->sector
55 static kmem_cache_t
*crq_pool
;
56 static kmem_cache_t
*cfq_pool
;
57 static kmem_cache_t
*cfq_ioc_pool
;
59 static atomic_t ioc_count
= ATOMIC_INIT(0);
60 static struct completion
*ioc_gone
;
62 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
63 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
64 #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
70 #define cfq_cfqq_dispatched(cfqq) \
71 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
73 #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
75 #define cfq_cfqq_sync(cfqq) \
76 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
78 #define sample_valid(samples) ((samples) > 80)
81 * Per block device queue structure
84 request_queue_t
*queue
;
87 * rr list of queues with requests and the count of them
89 struct list_head rr_list
[CFQ_PRIO_LISTS
];
90 struct list_head busy_rr
;
91 struct list_head cur_rr
;
92 struct list_head idle_rr
;
93 unsigned int busy_queues
;
96 * non-ordered list of empty cfqq's
98 struct list_head empty_list
;
103 struct hlist_head
*cfq_hash
;
111 * schedule slice state info
114 * idle window management
116 struct timer_list idle_slice_timer
;
117 struct work_struct unplug_work
;
119 struct cfq_queue
*active_queue
;
120 struct cfq_io_context
*active_cic
;
121 int cur_prio
, cur_end_prio
;
122 unsigned int dispatch_slice
;
124 struct timer_list idle_class_timer
;
126 sector_t last_sector
;
127 unsigned long last_end_request
;
129 unsigned int rq_starved
;
132 * tunables, see top of file
134 unsigned int cfq_quantum
;
135 unsigned int cfq_queued
;
136 unsigned int cfq_fifo_expire
[2];
137 unsigned int cfq_back_penalty
;
138 unsigned int cfq_back_max
;
139 unsigned int cfq_slice
[2];
140 unsigned int cfq_slice_async_rq
;
141 unsigned int cfq_slice_idle
;
143 struct list_head cic_list
;
147 * Per process-grouping structure
150 /* reference count */
152 /* parent cfq_data */
153 struct cfq_data
*cfqd
;
154 /* cfqq lookup hash */
155 struct hlist_node cfq_hash
;
158 /* on either rr or empty list of cfqd */
159 struct list_head cfq_list
;
160 /* sorted list of pending requests */
161 struct rb_root sort_list
;
162 /* if fifo isn't expired, next request to serve */
163 struct cfq_rq
*next_crq
;
164 /* requests queued in sort_list */
166 /* currently allocated requests */
168 /* fifo list of requests in sort_list */
169 struct list_head fifo
;
171 unsigned long slice_start
;
172 unsigned long slice_end
;
173 unsigned long slice_left
;
174 unsigned long service_last
;
176 /* number of requests that are on the dispatch list */
179 /* io prio of this group */
180 unsigned short ioprio
, org_ioprio
;
181 unsigned short ioprio_class
, org_ioprio_class
;
183 /* various state flags, see below */
188 struct rb_node rb_node
;
190 struct request
*request
;
192 struct cfq_queue
*cfq_queue
;
193 struct cfq_io_context
*io_context
;
195 unsigned int crq_flags
;
198 enum cfqq_state_flags
{
199 CFQ_CFQQ_FLAG_on_rr
= 0,
200 CFQ_CFQQ_FLAG_wait_request
,
201 CFQ_CFQQ_FLAG_must_alloc
,
202 CFQ_CFQQ_FLAG_must_alloc_slice
,
203 CFQ_CFQQ_FLAG_must_dispatch
,
204 CFQ_CFQQ_FLAG_fifo_expire
,
205 CFQ_CFQQ_FLAG_idle_window
,
206 CFQ_CFQQ_FLAG_prio_changed
,
209 #define CFQ_CFQQ_FNS(name) \
210 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
212 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
214 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
216 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
218 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
220 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
224 CFQ_CFQQ_FNS(wait_request
);
225 CFQ_CFQQ_FNS(must_alloc
);
226 CFQ_CFQQ_FNS(must_alloc_slice
);
227 CFQ_CFQQ_FNS(must_dispatch
);
228 CFQ_CFQQ_FNS(fifo_expire
);
229 CFQ_CFQQ_FNS(idle_window
);
230 CFQ_CFQQ_FNS(prio_changed
);
233 enum cfq_rq_state_flags
{
234 CFQ_CRQ_FLAG_is_sync
= 0,
237 #define CFQ_CRQ_FNS(name) \
238 static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
240 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
242 static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
244 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
246 static inline int cfq_crq_##name(const struct cfq_rq *crq) \
248 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
251 CFQ_CRQ_FNS(is_sync
);
254 static struct cfq_queue
*cfq_find_cfq_hash(struct cfq_data
*, unsigned int, unsigned short);
255 static void cfq_dispatch_insert(request_queue_t
*, struct cfq_rq
*);
256 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, struct task_struct
*tsk
, gfp_t gfp_mask
);
259 * scheduler run of queue, if there are requests pending and no one in the
260 * driver that will restart queueing
262 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
264 if (cfqd
->busy_queues
)
265 kblockd_schedule_work(&cfqd
->unplug_work
);
268 static int cfq_queue_empty(request_queue_t
*q
)
270 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
272 return !cfqd
->busy_queues
;
275 static inline pid_t
cfq_queue_pid(struct task_struct
*task
, int rw
)
277 if (rw
== READ
|| rw
== WRITE_SYNC
)
280 return CFQ_KEY_ASYNC
;
284 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
285 * We choose the request that is closest to the head right now. Distance
286 * behind the head is penalized and only allowed to a certain extent.
288 static struct cfq_rq
*
289 cfq_choose_req(struct cfq_data
*cfqd
, struct cfq_rq
*crq1
, struct cfq_rq
*crq2
)
291 sector_t last
, s1
, s2
, d1
= 0, d2
= 0;
292 unsigned long back_max
;
293 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
294 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
295 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
297 if (crq1
== NULL
|| crq1
== crq2
)
302 if (cfq_crq_is_sync(crq1
) && !cfq_crq_is_sync(crq2
))
304 else if (cfq_crq_is_sync(crq2
) && !cfq_crq_is_sync(crq1
))
307 s1
= crq1
->request
->sector
;
308 s2
= crq2
->request
->sector
;
310 last
= cfqd
->last_sector
;
313 * by definition, 1KiB is 2 sectors
315 back_max
= cfqd
->cfq_back_max
* 2;
318 * Strict one way elevator _except_ in the case where we allow
319 * short backward seeks which are biased as twice the cost of a
320 * similar forward seek.
324 else if (s1
+ back_max
>= last
)
325 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
327 wrap
|= CFQ_RQ1_WRAP
;
331 else if (s2
+ back_max
>= last
)
332 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
334 wrap
|= CFQ_RQ2_WRAP
;
336 /* Found required data */
339 * By doing switch() on the bit mask "wrap" we avoid having to
340 * check two variables for all permutations: --> faster!
343 case 0: /* common case for CFQ: crq1 and crq2 not wrapped */
359 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both crqs wrapped */
362 * Since both rqs are wrapped,
363 * start with the one that's further behind head
364 * (--> only *one* back seek required),
365 * since back seek takes more time than forward.
375 * would be nice to take fifo expire time into account as well
377 static struct cfq_rq
*
378 cfq_find_next_crq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
381 struct cfq_rq
*crq_next
= NULL
, *crq_prev
= NULL
;
382 struct rb_node
*rbnext
, *rbprev
;
384 if (!(rbnext
= rb_next(&last
->rb_node
))) {
385 rbnext
= rb_first(&cfqq
->sort_list
);
386 if (rbnext
== &last
->rb_node
)
390 rbprev
= rb_prev(&last
->rb_node
);
393 crq_prev
= rb_entry_crq(rbprev
);
395 crq_next
= rb_entry_crq(rbnext
);
397 return cfq_choose_req(cfqd
, crq_next
, crq_prev
);
400 static void cfq_update_next_crq(struct cfq_rq
*crq
)
402 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
404 if (cfqq
->next_crq
== crq
)
405 cfqq
->next_crq
= cfq_find_next_crq(cfqq
->cfqd
, cfqq
, crq
);
408 static void cfq_resort_rr_list(struct cfq_queue
*cfqq
, int preempted
)
410 struct cfq_data
*cfqd
= cfqq
->cfqd
;
411 struct list_head
*list
, *entry
;
413 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
415 list_del(&cfqq
->cfq_list
);
417 if (cfq_class_rt(cfqq
))
418 list
= &cfqd
->cur_rr
;
419 else if (cfq_class_idle(cfqq
))
420 list
= &cfqd
->idle_rr
;
423 * if cfqq has requests in flight, don't allow it to be
424 * found in cfq_set_active_queue before it has finished them.
425 * this is done to increase fairness between a process that
426 * has lots of io pending vs one that only generates one
427 * sporadically or synchronously
429 if (cfq_cfqq_dispatched(cfqq
))
430 list
= &cfqd
->busy_rr
;
432 list
= &cfqd
->rr_list
[cfqq
->ioprio
];
436 * if queue was preempted, just add to front to be fair. busy_rr
437 * isn't sorted, but insert at the back for fairness.
439 if (preempted
|| list
== &cfqd
->busy_rr
) {
443 list_add_tail(&cfqq
->cfq_list
, list
);
448 * sort by when queue was last serviced
451 while ((entry
= entry
->prev
) != list
) {
452 struct cfq_queue
*__cfqq
= list_entry_cfqq(entry
);
454 if (!__cfqq
->service_last
)
456 if (time_before(__cfqq
->service_last
, cfqq
->service_last
))
460 list_add(&cfqq
->cfq_list
, entry
);
464 * add to busy list of queues for service, trying to be fair in ordering
465 * the pending list according to last request service
468 cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
470 BUG_ON(cfq_cfqq_on_rr(cfqq
));
471 cfq_mark_cfqq_on_rr(cfqq
);
474 cfq_resort_rr_list(cfqq
, 0);
478 cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
480 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
481 cfq_clear_cfqq_on_rr(cfqq
);
482 list_move(&cfqq
->cfq_list
, &cfqd
->empty_list
);
484 BUG_ON(!cfqd
->busy_queues
);
489 * rb tree support functions
491 static inline void cfq_del_crq_rb(struct cfq_rq
*crq
)
493 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
494 struct cfq_data
*cfqd
= cfqq
->cfqd
;
495 const int sync
= cfq_crq_is_sync(crq
);
497 BUG_ON(!cfqq
->queued
[sync
]);
498 cfqq
->queued
[sync
]--;
500 cfq_update_next_crq(crq
);
502 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
504 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
505 cfq_del_cfqq_rr(cfqd
, cfqq
);
508 static struct cfq_rq
*
509 __cfq_add_crq_rb(struct cfq_rq
*crq
)
511 struct rb_node
**p
= &crq
->cfq_queue
->sort_list
.rb_node
;
512 struct rb_node
*parent
= NULL
;
513 struct cfq_rq
*__crq
;
517 __crq
= rb_entry_crq(parent
);
519 if (crq
->rb_key
< __crq
->rb_key
)
521 else if (crq
->rb_key
> __crq
->rb_key
)
527 rb_link_node(&crq
->rb_node
, parent
, p
);
531 static void cfq_add_crq_rb(struct cfq_rq
*crq
)
533 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
534 struct cfq_data
*cfqd
= cfqq
->cfqd
;
535 struct request
*rq
= crq
->request
;
536 struct cfq_rq
*__alias
;
538 crq
->rb_key
= rq_rb_key(rq
);
539 cfqq
->queued
[cfq_crq_is_sync(crq
)]++;
542 * looks a little odd, but the first insert might return an alias.
543 * if that happens, put the alias on the dispatch list
545 while ((__alias
= __cfq_add_crq_rb(crq
)) != NULL
)
546 cfq_dispatch_insert(cfqd
->queue
, __alias
);
548 rb_insert_color(&crq
->rb_node
, &cfqq
->sort_list
);
550 if (!cfq_cfqq_on_rr(cfqq
))
551 cfq_add_cfqq_rr(cfqd
, cfqq
);
554 * check if this request is a better next-serve candidate
556 cfqq
->next_crq
= cfq_choose_req(cfqd
, cfqq
->next_crq
, crq
);
560 cfq_reposition_crq_rb(struct cfq_queue
*cfqq
, struct cfq_rq
*crq
)
562 rb_erase(&crq
->rb_node
, &cfqq
->sort_list
);
563 cfqq
->queued
[cfq_crq_is_sync(crq
)]--;
568 static struct request
*
569 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
571 struct task_struct
*tsk
= current
;
572 pid_t key
= cfq_queue_pid(tsk
, bio_data_dir(bio
));
573 struct cfq_queue
*cfqq
;
577 cfqq
= cfq_find_cfq_hash(cfqd
, key
, tsk
->ioprio
);
581 sector
= bio
->bi_sector
+ bio_sectors(bio
);
582 n
= cfqq
->sort_list
.rb_node
;
584 struct cfq_rq
*crq
= rb_entry_crq(n
);
586 if (sector
< crq
->rb_key
)
588 else if (sector
> crq
->rb_key
)
598 static void cfq_activate_request(request_queue_t
*q
, struct request
*rq
)
600 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
602 cfqd
->rq_in_driver
++;
605 * If the depth is larger 1, it really could be queueing. But lets
606 * make the mark a little higher - idling could still be good for
607 * low queueing, and a low queueing number could also just indicate
608 * a SCSI mid layer like behaviour where limit+1 is often seen.
610 if (!cfqd
->hw_tag
&& cfqd
->rq_in_driver
> 4)
614 static void cfq_deactivate_request(request_queue_t
*q
, struct request
*rq
)
616 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
618 WARN_ON(!cfqd
->rq_in_driver
);
619 cfqd
->rq_in_driver
--;
622 static void cfq_remove_request(struct request
*rq
)
624 struct cfq_rq
*crq
= RQ_DATA(rq
);
626 list_del_init(&rq
->queuelist
);
631 cfq_merge(request_queue_t
*q
, struct request
**req
, struct bio
*bio
)
633 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
634 struct request
*__rq
;
636 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
637 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
639 return ELEVATOR_FRONT_MERGE
;
642 return ELEVATOR_NO_MERGE
;
645 static void cfq_merged_request(request_queue_t
*q
, struct request
*req
)
647 struct cfq_rq
*crq
= RQ_DATA(req
);
649 if (rq_rb_key(req
) != crq
->rb_key
) {
650 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
652 cfq_update_next_crq(crq
);
653 cfq_reposition_crq_rb(cfqq
, crq
);
658 cfq_merged_requests(request_queue_t
*q
, struct request
*rq
,
659 struct request
*next
)
661 cfq_merged_request(q
, rq
);
664 * reposition in fifo if next is older than rq
666 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
667 time_before(next
->start_time
, rq
->start_time
))
668 list_move(&rq
->queuelist
, &next
->queuelist
);
670 cfq_remove_request(next
);
674 __cfq_set_active_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
678 * stop potential idle class queues waiting service
680 del_timer(&cfqd
->idle_class_timer
);
682 cfqq
->slice_start
= jiffies
;
684 cfqq
->slice_left
= 0;
685 cfq_clear_cfqq_must_alloc_slice(cfqq
);
686 cfq_clear_cfqq_fifo_expire(cfqq
);
689 cfqd
->active_queue
= cfqq
;
693 * current cfqq expired its slice (or was too idle), select new one
696 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
699 unsigned long now
= jiffies
;
701 if (cfq_cfqq_wait_request(cfqq
))
702 del_timer(&cfqd
->idle_slice_timer
);
704 if (!preempted
&& !cfq_cfqq_dispatched(cfqq
)) {
705 cfqq
->service_last
= now
;
706 cfq_schedule_dispatch(cfqd
);
709 cfq_clear_cfqq_must_dispatch(cfqq
);
710 cfq_clear_cfqq_wait_request(cfqq
);
713 * store what was left of this slice, if the queue idled out
716 if (time_after(cfqq
->slice_end
, now
))
717 cfqq
->slice_left
= cfqq
->slice_end
- now
;
719 cfqq
->slice_left
= 0;
721 if (cfq_cfqq_on_rr(cfqq
))
722 cfq_resort_rr_list(cfqq
, preempted
);
724 if (cfqq
== cfqd
->active_queue
)
725 cfqd
->active_queue
= NULL
;
727 if (cfqd
->active_cic
) {
728 put_io_context(cfqd
->active_cic
->ioc
);
729 cfqd
->active_cic
= NULL
;
732 cfqd
->dispatch_slice
= 0;
735 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, int preempted
)
737 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
740 __cfq_slice_expired(cfqd
, cfqq
, preempted
);
753 static int cfq_get_next_prio_level(struct cfq_data
*cfqd
)
762 for (p
= cfqd
->cur_prio
; p
<= cfqd
->cur_end_prio
; p
++) {
763 if (!list_empty(&cfqd
->rr_list
[p
])) {
772 if (++cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
773 cfqd
->cur_end_prio
= 0;
780 if (unlikely(prio
== -1))
783 BUG_ON(prio
>= CFQ_PRIO_LISTS
);
785 list_splice_init(&cfqd
->rr_list
[prio
], &cfqd
->cur_rr
);
787 cfqd
->cur_prio
= prio
+ 1;
788 if (cfqd
->cur_prio
> cfqd
->cur_end_prio
) {
789 cfqd
->cur_end_prio
= cfqd
->cur_prio
;
792 if (cfqd
->cur_end_prio
== CFQ_PRIO_LISTS
) {
794 cfqd
->cur_end_prio
= 0;
800 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
)
802 struct cfq_queue
*cfqq
= NULL
;
805 * if current list is non-empty, grab first entry. if it is empty,
806 * get next prio level and grab first entry then if any are spliced
808 if (!list_empty(&cfqd
->cur_rr
) || cfq_get_next_prio_level(cfqd
) != -1)
809 cfqq
= list_entry_cfqq(cfqd
->cur_rr
.next
);
812 * If no new queues are available, check if the busy list has some
813 * before falling back to idle io.
815 if (!cfqq
&& !list_empty(&cfqd
->busy_rr
))
816 cfqq
= list_entry_cfqq(cfqd
->busy_rr
.next
);
819 * if we have idle queues and no rt or be queues had pending
820 * requests, either allow immediate service if the grace period
821 * has passed or arm the idle grace timer
823 if (!cfqq
&& !list_empty(&cfqd
->idle_rr
)) {
824 unsigned long end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
826 if (time_after_eq(jiffies
, end
))
827 cfqq
= list_entry_cfqq(cfqd
->idle_rr
.next
);
829 mod_timer(&cfqd
->idle_class_timer
, end
);
832 __cfq_set_active_queue(cfqd
, cfqq
);
836 #define CIC_SEEKY(cic) ((cic)->seek_mean > (128 * 1024))
838 static int cfq_arm_slice_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
841 struct cfq_io_context
*cic
;
844 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
845 WARN_ON(cfqq
!= cfqd
->active_queue
);
848 * idle is disabled, either manually or by past process history
850 if (!cfqd
->cfq_slice_idle
)
852 if (!cfq_cfqq_idle_window(cfqq
))
855 * task has exited, don't wait
857 cic
= cfqd
->active_cic
;
858 if (!cic
|| !cic
->ioc
->task
)
861 cfq_mark_cfqq_must_dispatch(cfqq
);
862 cfq_mark_cfqq_wait_request(cfqq
);
864 sl
= min(cfqq
->slice_end
- 1, (unsigned long) cfqd
->cfq_slice_idle
);
867 * we don't want to idle for seeks, but we do want to allow
868 * fair distribution of slice time for a process doing back-to-back
869 * seeks. so allow a little bit of time for him to submit a new rq
871 if (sample_valid(cic
->seek_samples
) && CIC_SEEKY(cic
))
872 sl
= min(sl
, msecs_to_jiffies(2));
874 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
878 static void cfq_dispatch_insert(request_queue_t
*q
, struct cfq_rq
*crq
)
880 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
881 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
884 cfqq
->next_crq
= cfq_find_next_crq(cfqd
, cfqq
, crq
);
885 cfq_remove_request(crq
->request
);
886 cfqq
->on_dispatch
[cfq_crq_is_sync(crq
)]++;
887 elv_dispatch_sort(q
, crq
->request
);
889 rq
= list_entry(q
->queue_head
.prev
, struct request
, queuelist
);
890 cfqd
->last_sector
= rq
->sector
+ rq
->nr_sectors
;
894 * return expired entry, or NULL to just start from scratch in rbtree
896 static inline struct cfq_rq
*cfq_check_fifo(struct cfq_queue
*cfqq
)
898 struct cfq_data
*cfqd
= cfqq
->cfqd
;
902 if (cfq_cfqq_fifo_expire(cfqq
))
905 if (!list_empty(&cfqq
->fifo
)) {
906 int fifo
= cfq_cfqq_class_sync(cfqq
);
908 crq
= RQ_DATA(list_entry_fifo(cfqq
->fifo
.next
));
910 if (time_after(jiffies
, rq
->start_time
+ cfqd
->cfq_fifo_expire
[fifo
])) {
911 cfq_mark_cfqq_fifo_expire(cfqq
);
920 * Scale schedule slice based on io priority. Use the sync time slice only
921 * if a queue is marked sync and has sync io queued. A sync queue with async
922 * io only, should not get full sync slice length.
925 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
927 const int base_slice
= cfqd
->cfq_slice
[cfq_cfqq_sync(cfqq
)];
929 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
931 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - cfqq
->ioprio
));
935 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
937 cfqq
->slice_end
= cfq_prio_to_slice(cfqd
, cfqq
) + jiffies
;
941 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
943 const int base_rq
= cfqd
->cfq_slice_async_rq
;
945 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
947 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
951 * get next queue for service
953 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
955 unsigned long now
= jiffies
;
956 struct cfq_queue
*cfqq
;
958 cfqq
= cfqd
->active_queue
;
965 if (!cfq_cfqq_must_dispatch(cfqq
) && time_after(now
, cfqq
->slice_end
))
969 * if queue has requests, dispatch one. if not, check if
970 * enough slice is left to wait for one
972 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
974 else if (cfq_cfqq_dispatched(cfqq
)) {
977 } else if (cfq_cfqq_class_sync(cfqq
)) {
978 if (cfq_arm_slice_timer(cfqd
, cfqq
))
983 cfq_slice_expired(cfqd
, 0);
985 cfqq
= cfq_set_active_queue(cfqd
);
991 __cfq_dispatch_requests(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
996 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
1002 * follow expired path, else get first next available
1004 if ((crq
= cfq_check_fifo(cfqq
)) == NULL
)
1005 crq
= cfqq
->next_crq
;
1008 * finally, insert request into driver dispatch list
1010 cfq_dispatch_insert(cfqd
->queue
, crq
);
1012 cfqd
->dispatch_slice
++;
1015 if (!cfqd
->active_cic
) {
1016 atomic_inc(&crq
->io_context
->ioc
->refcount
);
1017 cfqd
->active_cic
= crq
->io_context
;
1020 if (RB_EMPTY_ROOT(&cfqq
->sort_list
))
1023 } while (dispatched
< max_dispatch
);
1026 * if slice end isn't set yet, set it.
1028 if (!cfqq
->slice_end
)
1029 cfq_set_prio_slice(cfqd
, cfqq
);
1032 * expire an async queue immediately if it has used up its slice. idle
1033 * queue always expire after 1 dispatch round.
1035 if ((!cfq_cfqq_sync(cfqq
) &&
1036 cfqd
->dispatch_slice
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1037 cfq_class_idle(cfqq
) ||
1038 !cfq_cfqq_idle_window(cfqq
))
1039 cfq_slice_expired(cfqd
, 0);
1045 cfq_forced_dispatch_cfqqs(struct list_head
*list
)
1047 struct cfq_queue
*cfqq
, *next
;
1052 list_for_each_entry_safe(cfqq
, next
, list
, cfq_list
) {
1053 while ((crq
= cfqq
->next_crq
)) {
1054 cfq_dispatch_insert(cfqq
->cfqd
->queue
, crq
);
1057 BUG_ON(!list_empty(&cfqq
->fifo
));
1064 cfq_forced_dispatch(struct cfq_data
*cfqd
)
1066 int i
, dispatched
= 0;
1068 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
1069 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->rr_list
[i
]);
1071 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->busy_rr
);
1072 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->cur_rr
);
1073 dispatched
+= cfq_forced_dispatch_cfqqs(&cfqd
->idle_rr
);
1075 cfq_slice_expired(cfqd
, 0);
1077 BUG_ON(cfqd
->busy_queues
);
1083 cfq_dispatch_requests(request_queue_t
*q
, int force
)
1085 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1086 struct cfq_queue
*cfqq
, *prev_cfqq
;
1089 if (!cfqd
->busy_queues
)
1092 if (unlikely(force
))
1093 return cfq_forced_dispatch(cfqd
);
1097 while ((cfqq
= cfq_select_queue(cfqd
)) != NULL
) {
1101 * Don't repeat dispatch from the previous queue.
1103 if (prev_cfqq
== cfqq
)
1106 cfq_clear_cfqq_must_dispatch(cfqq
);
1107 cfq_clear_cfqq_wait_request(cfqq
);
1108 del_timer(&cfqd
->idle_slice_timer
);
1110 max_dispatch
= cfqd
->cfq_quantum
;
1111 if (cfq_class_idle(cfqq
))
1114 dispatched
+= __cfq_dispatch_requests(cfqd
, cfqq
, max_dispatch
);
1117 * If the dispatch cfqq has idling enabled and is still
1118 * the active queue, break out.
1120 if (cfq_cfqq_idle_window(cfqq
) && cfqd
->active_queue
)
1130 * task holds one reference to the queue, dropped when task exits. each crq
1131 * in-flight on this queue also holds a reference, dropped when crq is freed.
1133 * queue lock must be held here.
1135 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1137 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1139 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1141 if (!atomic_dec_and_test(&cfqq
->ref
))
1144 BUG_ON(rb_first(&cfqq
->sort_list
));
1145 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1146 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1148 if (unlikely(cfqd
->active_queue
== cfqq
))
1149 __cfq_slice_expired(cfqd
, cfqq
, 0);
1152 * it's on the empty list and still hashed
1154 list_del(&cfqq
->cfq_list
);
1155 hlist_del(&cfqq
->cfq_hash
);
1156 kmem_cache_free(cfq_pool
, cfqq
);
1159 static inline struct cfq_queue
*
1160 __cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned int prio
,
1163 struct hlist_head
*hash_list
= &cfqd
->cfq_hash
[hashval
];
1164 struct hlist_node
*entry
;
1165 struct cfq_queue
*__cfqq
;
1167 hlist_for_each_entry(__cfqq
, entry
, hash_list
, cfq_hash
) {
1168 const unsigned short __p
= IOPRIO_PRIO_VALUE(__cfqq
->org_ioprio_class
, __cfqq
->org_ioprio
);
1170 if (__cfqq
->key
== key
&& (__p
== prio
|| !prio
))
1177 static struct cfq_queue
*
1178 cfq_find_cfq_hash(struct cfq_data
*cfqd
, unsigned int key
, unsigned short prio
)
1180 return __cfq_find_cfq_hash(cfqd
, key
, prio
, hash_long(key
, CFQ_QHASH_SHIFT
));
1183 static void cfq_free_io_context(struct io_context
*ioc
)
1185 struct cfq_io_context
*__cic
;
1189 while ((n
= rb_first(&ioc
->cic_root
)) != NULL
) {
1190 __cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1191 rb_erase(&__cic
->rb_node
, &ioc
->cic_root
);
1192 kmem_cache_free(cfq_ioc_pool
, __cic
);
1196 if (atomic_sub_and_test(freed
, &ioc_count
) && ioc_gone
)
1200 static void cfq_trim(struct io_context
*ioc
)
1202 ioc
->set_ioprio
= NULL
;
1203 cfq_free_io_context(ioc
);
1207 * Called with interrupts disabled
1209 static void cfq_exit_single_io_context(struct cfq_io_context
*cic
)
1211 struct cfq_data
*cfqd
= cic
->key
;
1219 WARN_ON(!irqs_disabled());
1221 spin_lock(q
->queue_lock
);
1223 if (cic
->cfqq
[ASYNC
]) {
1224 if (unlikely(cic
->cfqq
[ASYNC
] == cfqd
->active_queue
))
1225 __cfq_slice_expired(cfqd
, cic
->cfqq
[ASYNC
], 0);
1226 cfq_put_queue(cic
->cfqq
[ASYNC
]);
1227 cic
->cfqq
[ASYNC
] = NULL
;
1230 if (cic
->cfqq
[SYNC
]) {
1231 if (unlikely(cic
->cfqq
[SYNC
] == cfqd
->active_queue
))
1232 __cfq_slice_expired(cfqd
, cic
->cfqq
[SYNC
], 0);
1233 cfq_put_queue(cic
->cfqq
[SYNC
]);
1234 cic
->cfqq
[SYNC
] = NULL
;
1238 list_del_init(&cic
->queue_list
);
1239 spin_unlock(q
->queue_lock
);
1242 static void cfq_exit_io_context(struct io_context
*ioc
)
1244 struct cfq_io_context
*__cic
;
1245 unsigned long flags
;
1249 * put the reference this task is holding to the various queues
1251 spin_lock_irqsave(&cfq_exit_lock
, flags
);
1253 n
= rb_first(&ioc
->cic_root
);
1255 __cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1257 cfq_exit_single_io_context(__cic
);
1261 spin_unlock_irqrestore(&cfq_exit_lock
, flags
);
1264 static struct cfq_io_context
*
1265 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1267 struct cfq_io_context
*cic
= kmem_cache_alloc(cfq_ioc_pool
, gfp_mask
);
1270 memset(cic
, 0, sizeof(*cic
));
1271 cic
->last_end_request
= jiffies
;
1272 INIT_LIST_HEAD(&cic
->queue_list
);
1273 cic
->dtor
= cfq_free_io_context
;
1274 cic
->exit
= cfq_exit_io_context
;
1275 atomic_inc(&ioc_count
);
1281 static void cfq_init_prio_data(struct cfq_queue
*cfqq
)
1283 struct task_struct
*tsk
= current
;
1286 if (!cfq_cfqq_prio_changed(cfqq
))
1289 ioprio_class
= IOPRIO_PRIO_CLASS(tsk
->ioprio
);
1290 switch (ioprio_class
) {
1292 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1293 case IOPRIO_CLASS_NONE
:
1295 * no prio set, place us in the middle of the BE classes
1297 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1298 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1300 case IOPRIO_CLASS_RT
:
1301 cfqq
->ioprio
= task_ioprio(tsk
);
1302 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1304 case IOPRIO_CLASS_BE
:
1305 cfqq
->ioprio
= task_ioprio(tsk
);
1306 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1308 case IOPRIO_CLASS_IDLE
:
1309 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
1311 cfq_clear_cfqq_idle_window(cfqq
);
1316 * keep track of original prio settings in case we have to temporarily
1317 * elevate the priority of this queue
1319 cfqq
->org_ioprio
= cfqq
->ioprio
;
1320 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
1322 if (cfq_cfqq_on_rr(cfqq
))
1323 cfq_resort_rr_list(cfqq
, 0);
1325 cfq_clear_cfqq_prio_changed(cfqq
);
1328 static inline void changed_ioprio(struct cfq_io_context
*cic
)
1330 struct cfq_data
*cfqd
= cic
->key
;
1331 struct cfq_queue
*cfqq
;
1333 if (unlikely(!cfqd
))
1336 spin_lock(cfqd
->queue
->queue_lock
);
1338 cfqq
= cic
->cfqq
[ASYNC
];
1340 struct cfq_queue
*new_cfqq
;
1341 new_cfqq
= cfq_get_queue(cfqd
, CFQ_KEY_ASYNC
, cic
->ioc
->task
,
1344 cic
->cfqq
[ASYNC
] = new_cfqq
;
1345 cfq_put_queue(cfqq
);
1349 cfqq
= cic
->cfqq
[SYNC
];
1351 cfq_mark_cfqq_prio_changed(cfqq
);
1353 spin_unlock(cfqd
->queue
->queue_lock
);
1357 * callback from sys_ioprio_set, irqs are disabled
1359 static int cfq_ioc_set_ioprio(struct io_context
*ioc
, unsigned int ioprio
)
1361 struct cfq_io_context
*cic
;
1364 spin_lock(&cfq_exit_lock
);
1366 n
= rb_first(&ioc
->cic_root
);
1368 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1370 changed_ioprio(cic
);
1374 spin_unlock(&cfq_exit_lock
);
1379 static struct cfq_queue
*
1380 cfq_get_queue(struct cfq_data
*cfqd
, unsigned int key
, struct task_struct
*tsk
,
1383 const int hashval
= hash_long(key
, CFQ_QHASH_SHIFT
);
1384 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1385 unsigned short ioprio
;
1388 ioprio
= tsk
->ioprio
;
1389 cfqq
= __cfq_find_cfq_hash(cfqd
, key
, ioprio
, hashval
);
1395 } else if (gfp_mask
& __GFP_WAIT
) {
1396 spin_unlock_irq(cfqd
->queue
->queue_lock
);
1397 new_cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1398 spin_lock_irq(cfqd
->queue
->queue_lock
);
1401 cfqq
= kmem_cache_alloc(cfq_pool
, gfp_mask
);
1406 memset(cfqq
, 0, sizeof(*cfqq
));
1408 INIT_HLIST_NODE(&cfqq
->cfq_hash
);
1409 INIT_LIST_HEAD(&cfqq
->cfq_list
);
1410 INIT_LIST_HEAD(&cfqq
->fifo
);
1413 hlist_add_head(&cfqq
->cfq_hash
, &cfqd
->cfq_hash
[hashval
]);
1414 atomic_set(&cfqq
->ref
, 0);
1416 cfqq
->service_last
= 0;
1418 * set ->slice_left to allow preemption for a new process
1420 cfqq
->slice_left
= 2 * cfqd
->cfq_slice_idle
;
1421 cfq_mark_cfqq_idle_window(cfqq
);
1422 cfq_mark_cfqq_prio_changed(cfqq
);
1423 cfq_init_prio_data(cfqq
);
1427 kmem_cache_free(cfq_pool
, new_cfqq
);
1429 atomic_inc(&cfqq
->ref
);
1431 WARN_ON((gfp_mask
& __GFP_WAIT
) && !cfqq
);
1436 cfq_drop_dead_cic(struct io_context
*ioc
, struct cfq_io_context
*cic
)
1438 spin_lock(&cfq_exit_lock
);
1439 rb_erase(&cic
->rb_node
, &ioc
->cic_root
);
1440 list_del_init(&cic
->queue_list
);
1441 spin_unlock(&cfq_exit_lock
);
1442 kmem_cache_free(cfq_ioc_pool
, cic
);
1443 atomic_dec(&ioc_count
);
1446 static struct cfq_io_context
*
1447 cfq_cic_rb_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
1450 struct cfq_io_context
*cic
;
1451 void *k
, *key
= cfqd
;
1454 n
= ioc
->cic_root
.rb_node
;
1456 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
1457 /* ->key must be copied to avoid race with cfq_exit_queue() */
1460 cfq_drop_dead_cic(ioc
, cic
);
1476 cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
1477 struct cfq_io_context
*cic
)
1480 struct rb_node
*parent
;
1481 struct cfq_io_context
*__cic
;
1487 ioc
->set_ioprio
= cfq_ioc_set_ioprio
;
1490 p
= &ioc
->cic_root
.rb_node
;
1493 __cic
= rb_entry(parent
, struct cfq_io_context
, rb_node
);
1494 /* ->key must be copied to avoid race with cfq_exit_queue() */
1497 cfq_drop_dead_cic(ioc
, __cic
);
1503 else if (cic
->key
> k
)
1504 p
= &(*p
)->rb_right
;
1509 spin_lock(&cfq_exit_lock
);
1510 rb_link_node(&cic
->rb_node
, parent
, p
);
1511 rb_insert_color(&cic
->rb_node
, &ioc
->cic_root
);
1512 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
1513 spin_unlock(&cfq_exit_lock
);
1517 * Setup general io context and cfq io context. There can be several cfq
1518 * io contexts per general io context, if this process is doing io to more
1519 * than one device managed by cfq.
1521 static struct cfq_io_context
*
1522 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1524 struct io_context
*ioc
= NULL
;
1525 struct cfq_io_context
*cic
;
1527 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1529 ioc
= get_io_context(gfp_mask
);
1533 cic
= cfq_cic_rb_lookup(cfqd
, ioc
);
1537 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
1541 cfq_cic_link(cfqd
, ioc
, cic
);
1545 put_io_context(ioc
);
1550 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
1552 unsigned long elapsed
, ttime
;
1555 * if this context already has stuff queued, thinktime is from
1556 * last queue not last end
1559 if (time_after(cic
->last_end_request
, cic
->last_queue
))
1560 elapsed
= jiffies
- cic
->last_end_request
;
1562 elapsed
= jiffies
- cic
->last_queue
;
1564 elapsed
= jiffies
- cic
->last_end_request
;
1567 ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
1569 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
1570 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
1571 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
1575 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
1581 if (cic
->last_request_pos
< crq
->request
->sector
)
1582 sdist
= crq
->request
->sector
- cic
->last_request_pos
;
1584 sdist
= cic
->last_request_pos
- crq
->request
->sector
;
1587 * Don't allow the seek distance to get too large from the
1588 * odd fragment, pagein, etc
1590 if (cic
->seek_samples
<= 60) /* second&third seek */
1591 sdist
= min(sdist
, (cic
->seek_mean
* 4) + 2*1024*1024);
1593 sdist
= min(sdist
, (cic
->seek_mean
* 4) + 2*1024*64);
1595 cic
->seek_samples
= (7*cic
->seek_samples
+ 256) / 8;
1596 cic
->seek_total
= (7*cic
->seek_total
+ (u64
)256*sdist
) / 8;
1597 total
= cic
->seek_total
+ (cic
->seek_samples
/2);
1598 do_div(total
, cic
->seek_samples
);
1599 cic
->seek_mean
= (sector_t
)total
;
1603 * Disable idle window if the process thinks too long or seeks so much that
1607 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1608 struct cfq_io_context
*cic
)
1610 int enable_idle
= cfq_cfqq_idle_window(cfqq
);
1612 if (!cic
->ioc
->task
|| !cfqd
->cfq_slice_idle
||
1613 (cfqd
->hw_tag
&& CIC_SEEKY(cic
)))
1615 else if (sample_valid(cic
->ttime_samples
)) {
1616 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
1623 cfq_mark_cfqq_idle_window(cfqq
);
1625 cfq_clear_cfqq_idle_window(cfqq
);
1630 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1631 * no or if we aren't sure, a 1 will cause a preempt.
1634 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
1637 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1639 if (cfq_class_idle(new_cfqq
))
1645 if (cfq_class_idle(cfqq
))
1647 if (!cfq_cfqq_wait_request(new_cfqq
))
1650 * if it doesn't have slice left, forget it
1652 if (new_cfqq
->slice_left
< cfqd
->cfq_slice_idle
)
1654 if (cfq_crq_is_sync(crq
) && !cfq_cfqq_sync(cfqq
))
1661 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1662 * let it have half of its nominal slice.
1664 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1666 struct cfq_queue
*__cfqq
, *next
;
1668 list_for_each_entry_safe(__cfqq
, next
, &cfqd
->cur_rr
, cfq_list
)
1669 cfq_resort_rr_list(__cfqq
, 1);
1671 if (!cfqq
->slice_left
)
1672 cfqq
->slice_left
= cfq_prio_to_slice(cfqd
, cfqq
) / 2;
1674 cfqq
->slice_end
= cfqq
->slice_left
+ jiffies
;
1675 cfq_slice_expired(cfqd
, 1);
1676 __cfq_set_active_queue(cfqd
, cfqq
);
1680 * should really be a ll_rw_blk.c helper
1682 static void cfq_start_queueing(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1684 request_queue_t
*q
= cfqd
->queue
;
1686 if (!blk_queue_plugged(q
))
1689 __generic_unplug_device(q
);
1693 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1694 * something we should do about it
1697 cfq_crq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1700 struct cfq_io_context
*cic
= crq
->io_context
;
1703 * we never wait for an async request and we don't allow preemption
1704 * of an async request. so just return early
1706 if (!cfq_crq_is_sync(crq
)) {
1708 * sync process issued an async request, if it's waiting
1709 * then expire it and kick rq handling.
1711 if (cic
== cfqd
->active_cic
&&
1712 del_timer(&cfqd
->idle_slice_timer
)) {
1713 cfq_slice_expired(cfqd
, 0);
1714 cfq_start_queueing(cfqd
, cfqq
);
1719 cfq_update_io_thinktime(cfqd
, cic
);
1720 cfq_update_io_seektime(cfqd
, cic
, crq
);
1721 cfq_update_idle_window(cfqd
, cfqq
, cic
);
1723 cic
->last_queue
= jiffies
;
1724 cic
->last_request_pos
= crq
->request
->sector
+ crq
->request
->nr_sectors
;
1726 if (cfqq
== cfqd
->active_queue
) {
1728 * if we are waiting for a request for this queue, let it rip
1729 * immediately and flag that we must not expire this queue
1732 if (cfq_cfqq_wait_request(cfqq
)) {
1733 cfq_mark_cfqq_must_dispatch(cfqq
);
1734 del_timer(&cfqd
->idle_slice_timer
);
1735 cfq_start_queueing(cfqd
, cfqq
);
1737 } else if (cfq_should_preempt(cfqd
, cfqq
, crq
)) {
1739 * not the active queue - expire current slice if it is
1740 * idle and has expired it's mean thinktime or this new queue
1741 * has some old slice time left and is of higher priority
1743 cfq_preempt_queue(cfqd
, cfqq
);
1744 cfq_mark_cfqq_must_dispatch(cfqq
);
1745 cfq_start_queueing(cfqd
, cfqq
);
1749 static void cfq_insert_request(request_queue_t
*q
, struct request
*rq
)
1751 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1752 struct cfq_rq
*crq
= RQ_DATA(rq
);
1753 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1755 cfq_init_prio_data(cfqq
);
1757 cfq_add_crq_rb(crq
);
1759 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
1761 cfq_crq_enqueued(cfqd
, cfqq
, crq
);
1764 static void cfq_completed_request(request_queue_t
*q
, struct request
*rq
)
1766 struct cfq_rq
*crq
= RQ_DATA(rq
);
1767 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1768 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1769 const int sync
= cfq_crq_is_sync(crq
);
1774 WARN_ON(!cfqd
->rq_in_driver
);
1775 WARN_ON(!cfqq
->on_dispatch
[sync
]);
1776 cfqd
->rq_in_driver
--;
1777 cfqq
->on_dispatch
[sync
]--;
1779 if (!cfq_class_idle(cfqq
))
1780 cfqd
->last_end_request
= now
;
1782 if (!cfq_cfqq_dispatched(cfqq
)) {
1783 if (cfq_cfqq_on_rr(cfqq
)) {
1784 cfqq
->service_last
= now
;
1785 cfq_resort_rr_list(cfqq
, 0);
1790 crq
->io_context
->last_end_request
= now
;
1793 * If this is the active queue, check if it needs to be expired,
1794 * or if we want to idle in case it has no pending requests.
1796 if (cfqd
->active_queue
== cfqq
) {
1797 if (time_after(now
, cfqq
->slice_end
))
1798 cfq_slice_expired(cfqd
, 0);
1799 else if (sync
&& RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1800 if (!cfq_arm_slice_timer(cfqd
, cfqq
))
1801 cfq_schedule_dispatch(cfqd
);
1806 static struct request
*
1807 cfq_former_request(request_queue_t
*q
, struct request
*rq
)
1809 struct cfq_rq
*crq
= RQ_DATA(rq
);
1810 struct rb_node
*rbprev
= rb_prev(&crq
->rb_node
);
1813 return rb_entry_crq(rbprev
)->request
;
1818 static struct request
*
1819 cfq_latter_request(request_queue_t
*q
, struct request
*rq
)
1821 struct cfq_rq
*crq
= RQ_DATA(rq
);
1822 struct rb_node
*rbnext
= rb_next(&crq
->rb_node
);
1825 return rb_entry_crq(rbnext
)->request
;
1831 * we temporarily boost lower priority queues if they are holding fs exclusive
1832 * resources. they are boosted to normal prio (CLASS_BE/4)
1834 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
1836 const int ioprio_class
= cfqq
->ioprio_class
;
1837 const int ioprio
= cfqq
->ioprio
;
1839 if (has_fs_excl()) {
1841 * boost idle prio on transactions that would lock out other
1842 * users of the filesystem
1844 if (cfq_class_idle(cfqq
))
1845 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1846 if (cfqq
->ioprio
> IOPRIO_NORM
)
1847 cfqq
->ioprio
= IOPRIO_NORM
;
1850 * check if we need to unboost the queue
1852 if (cfqq
->ioprio_class
!= cfqq
->org_ioprio_class
)
1853 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
1854 if (cfqq
->ioprio
!= cfqq
->org_ioprio
)
1855 cfqq
->ioprio
= cfqq
->org_ioprio
;
1859 * refile between round-robin lists if we moved the priority class
1861 if ((ioprio_class
!= cfqq
->ioprio_class
|| ioprio
!= cfqq
->ioprio
) &&
1862 cfq_cfqq_on_rr(cfqq
))
1863 cfq_resort_rr_list(cfqq
, 0);
1867 __cfq_may_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1868 struct task_struct
*task
, int rw
)
1870 if ((cfq_cfqq_wait_request(cfqq
) || cfq_cfqq_must_alloc(cfqq
)) &&
1871 !cfq_cfqq_must_alloc_slice(cfqq
)) {
1872 cfq_mark_cfqq_must_alloc_slice(cfqq
);
1873 return ELV_MQUEUE_MUST
;
1876 return ELV_MQUEUE_MAY
;
1879 static int cfq_may_queue(request_queue_t
*q
, int rw
, struct bio
*bio
)
1881 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1882 struct task_struct
*tsk
= current
;
1883 struct cfq_queue
*cfqq
;
1886 * don't force setup of a queue from here, as a call to may_queue
1887 * does not necessarily imply that a request actually will be queued.
1888 * so just lookup a possibly existing queue, or return 'may queue'
1891 cfqq
= cfq_find_cfq_hash(cfqd
, cfq_queue_pid(tsk
, rw
), tsk
->ioprio
);
1893 cfq_init_prio_data(cfqq
);
1894 cfq_prio_boost(cfqq
);
1896 return __cfq_may_queue(cfqd
, cfqq
, tsk
, rw
);
1899 return ELV_MQUEUE_MAY
;
1902 static void cfq_check_waiters(request_queue_t
*q
, struct cfq_queue
*cfqq
)
1904 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1906 if (unlikely(cfqd
->rq_starved
)) {
1907 struct request_list
*rl
= &q
->rq
;
1910 if (waitqueue_active(&rl
->wait
[READ
]))
1911 wake_up(&rl
->wait
[READ
]);
1912 if (waitqueue_active(&rl
->wait
[WRITE
]))
1913 wake_up(&rl
->wait
[WRITE
]);
1918 * queue lock held here
1920 static void cfq_put_request(request_queue_t
*q
, struct request
*rq
)
1922 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1923 struct cfq_rq
*crq
= RQ_DATA(rq
);
1926 struct cfq_queue
*cfqq
= crq
->cfq_queue
;
1927 const int rw
= rq_data_dir(rq
);
1929 BUG_ON(!cfqq
->allocated
[rw
]);
1930 cfqq
->allocated
[rw
]--;
1932 put_io_context(crq
->io_context
->ioc
);
1934 mempool_free(crq
, cfqd
->crq_pool
);
1935 rq
->elevator_private
= NULL
;
1937 cfq_check_waiters(q
, cfqq
);
1938 cfq_put_queue(cfqq
);
1943 * Allocate cfq data structures associated with this request.
1946 cfq_set_request(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
,
1949 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1950 struct task_struct
*tsk
= current
;
1951 struct cfq_io_context
*cic
;
1952 const int rw
= rq_data_dir(rq
);
1953 pid_t key
= cfq_queue_pid(tsk
, rw
);
1954 struct cfq_queue
*cfqq
;
1956 unsigned long flags
;
1957 int is_sync
= key
!= CFQ_KEY_ASYNC
;
1959 might_sleep_if(gfp_mask
& __GFP_WAIT
);
1961 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
1963 spin_lock_irqsave(q
->queue_lock
, flags
);
1968 if (!cic
->cfqq
[is_sync
]) {
1969 cfqq
= cfq_get_queue(cfqd
, key
, tsk
, gfp_mask
);
1973 cic
->cfqq
[is_sync
] = cfqq
;
1975 cfqq
= cic
->cfqq
[is_sync
];
1977 cfqq
->allocated
[rw
]++;
1978 cfq_clear_cfqq_must_alloc(cfqq
);
1979 cfqd
->rq_starved
= 0;
1980 atomic_inc(&cfqq
->ref
);
1981 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1983 crq
= mempool_alloc(cfqd
->crq_pool
, gfp_mask
);
1985 RB_CLEAR_NODE(&crq
->rb_node
);
1988 crq
->cfq_queue
= cfqq
;
1989 crq
->io_context
= cic
;
1992 cfq_mark_crq_is_sync(crq
);
1994 cfq_clear_crq_is_sync(crq
);
1996 rq
->elevator_private
= crq
;
2000 spin_lock_irqsave(q
->queue_lock
, flags
);
2001 cfqq
->allocated
[rw
]--;
2002 if (!(cfqq
->allocated
[0] + cfqq
->allocated
[1]))
2003 cfq_mark_cfqq_must_alloc(cfqq
);
2004 cfq_put_queue(cfqq
);
2007 put_io_context(cic
->ioc
);
2009 * mark us rq allocation starved. we need to kickstart the process
2010 * ourselves if there are no pending requests that can do it for us.
2011 * that would be an extremely rare OOM situation
2013 cfqd
->rq_starved
= 1;
2014 cfq_schedule_dispatch(cfqd
);
2015 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2019 static void cfq_kick_queue(void *data
)
2021 request_queue_t
*q
= data
;
2022 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2023 unsigned long flags
;
2025 spin_lock_irqsave(q
->queue_lock
, flags
);
2027 if (cfqd
->rq_starved
) {
2028 struct request_list
*rl
= &q
->rq
;
2031 * we aren't guaranteed to get a request after this, but we
2032 * have to be opportunistic
2035 if (waitqueue_active(&rl
->wait
[READ
]))
2036 wake_up(&rl
->wait
[READ
]);
2037 if (waitqueue_active(&rl
->wait
[WRITE
]))
2038 wake_up(&rl
->wait
[WRITE
]);
2043 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2047 * Timer running if the active_queue is currently idling inside its time slice
2049 static void cfq_idle_slice_timer(unsigned long data
)
2051 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2052 struct cfq_queue
*cfqq
;
2053 unsigned long flags
;
2055 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2057 if ((cfqq
= cfqd
->active_queue
) != NULL
) {
2058 unsigned long now
= jiffies
;
2063 if (time_after(now
, cfqq
->slice_end
))
2067 * only expire and reinvoke request handler, if there are
2068 * other queues with pending requests
2070 if (!cfqd
->busy_queues
)
2074 * not expired and it has a request pending, let it dispatch
2076 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
2077 cfq_mark_cfqq_must_dispatch(cfqq
);
2082 cfq_slice_expired(cfqd
, 0);
2084 cfq_schedule_dispatch(cfqd
);
2086 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2090 * Timer running if an idle class queue is waiting for service
2092 static void cfq_idle_class_timer(unsigned long data
)
2094 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2095 unsigned long flags
, end
;
2097 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2100 * race with a non-idle queue, reset timer
2102 end
= cfqd
->last_end_request
+ CFQ_IDLE_GRACE
;
2103 if (!time_after_eq(jiffies
, end
))
2104 mod_timer(&cfqd
->idle_class_timer
, end
);
2106 cfq_schedule_dispatch(cfqd
);
2108 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2111 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2113 del_timer_sync(&cfqd
->idle_slice_timer
);
2114 del_timer_sync(&cfqd
->idle_class_timer
);
2115 blk_sync_queue(cfqd
->queue
);
2118 static void cfq_exit_queue(elevator_t
*e
)
2120 struct cfq_data
*cfqd
= e
->elevator_data
;
2121 request_queue_t
*q
= cfqd
->queue
;
2123 cfq_shutdown_timer_wq(cfqd
);
2125 spin_lock(&cfq_exit_lock
);
2126 spin_lock_irq(q
->queue_lock
);
2128 if (cfqd
->active_queue
)
2129 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
2131 while (!list_empty(&cfqd
->cic_list
)) {
2132 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
2133 struct cfq_io_context
,
2135 if (cic
->cfqq
[ASYNC
]) {
2136 cfq_put_queue(cic
->cfqq
[ASYNC
]);
2137 cic
->cfqq
[ASYNC
] = NULL
;
2139 if (cic
->cfqq
[SYNC
]) {
2140 cfq_put_queue(cic
->cfqq
[SYNC
]);
2141 cic
->cfqq
[SYNC
] = NULL
;
2144 list_del_init(&cic
->queue_list
);
2147 spin_unlock_irq(q
->queue_lock
);
2148 spin_unlock(&cfq_exit_lock
);
2150 cfq_shutdown_timer_wq(cfqd
);
2152 mempool_destroy(cfqd
->crq_pool
);
2153 kfree(cfqd
->cfq_hash
);
2157 static void *cfq_init_queue(request_queue_t
*q
, elevator_t
*e
)
2159 struct cfq_data
*cfqd
;
2162 cfqd
= kmalloc(sizeof(*cfqd
), GFP_KERNEL
);
2166 memset(cfqd
, 0, sizeof(*cfqd
));
2168 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2169 INIT_LIST_HEAD(&cfqd
->rr_list
[i
]);
2171 INIT_LIST_HEAD(&cfqd
->busy_rr
);
2172 INIT_LIST_HEAD(&cfqd
->cur_rr
);
2173 INIT_LIST_HEAD(&cfqd
->idle_rr
);
2174 INIT_LIST_HEAD(&cfqd
->empty_list
);
2175 INIT_LIST_HEAD(&cfqd
->cic_list
);
2177 cfqd
->cfq_hash
= kmalloc(sizeof(struct hlist_head
) * CFQ_QHASH_ENTRIES
, GFP_KERNEL
);
2178 if (!cfqd
->cfq_hash
)
2181 cfqd
->crq_pool
= mempool_create_slab_pool(BLKDEV_MIN_RQ
, crq_pool
);
2182 if (!cfqd
->crq_pool
)
2185 for (i
= 0; i
< CFQ_QHASH_ENTRIES
; i
++)
2186 INIT_HLIST_HEAD(&cfqd
->cfq_hash
[i
]);
2190 init_timer(&cfqd
->idle_slice_timer
);
2191 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
2192 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
2194 init_timer(&cfqd
->idle_class_timer
);
2195 cfqd
->idle_class_timer
.function
= cfq_idle_class_timer
;
2196 cfqd
->idle_class_timer
.data
= (unsigned long) cfqd
;
2198 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
, q
);
2200 cfqd
->cfq_queued
= cfq_queued
;
2201 cfqd
->cfq_quantum
= cfq_quantum
;
2202 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
2203 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
2204 cfqd
->cfq_back_max
= cfq_back_max
;
2205 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
2206 cfqd
->cfq_slice
[0] = cfq_slice_async
;
2207 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
2208 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
2209 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
2213 kfree(cfqd
->cfq_hash
);
2219 static void cfq_slab_kill(void)
2222 kmem_cache_destroy(crq_pool
);
2224 kmem_cache_destroy(cfq_pool
);
2226 kmem_cache_destroy(cfq_ioc_pool
);
2229 static int __init
cfq_slab_setup(void)
2231 crq_pool
= kmem_cache_create("crq_pool", sizeof(struct cfq_rq
), 0, 0,
2236 cfq_pool
= kmem_cache_create("cfq_pool", sizeof(struct cfq_queue
), 0, 0,
2241 cfq_ioc_pool
= kmem_cache_create("cfq_ioc_pool",
2242 sizeof(struct cfq_io_context
), 0, 0, NULL
, NULL
);
2253 * sysfs parts below -->
2257 cfq_var_show(unsigned int var
, char *page
)
2259 return sprintf(page
, "%d\n", var
);
2263 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
2265 char *p
= (char *) page
;
2267 *var
= simple_strtoul(p
, &p
, 10);
2271 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2272 static ssize_t __FUNC(elevator_t *e, char *page) \
2274 struct cfq_data *cfqd = e->elevator_data; \
2275 unsigned int __data = __VAR; \
2277 __data = jiffies_to_msecs(__data); \
2278 return cfq_var_show(__data, (page)); \
2280 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
2281 SHOW_FUNCTION(cfq_queued_show
, cfqd
->cfq_queued
, 0);
2282 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
2283 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
2284 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
2285 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
2286 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
2287 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
2288 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
2289 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
2290 #undef SHOW_FUNCTION
2292 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2293 static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \
2295 struct cfq_data *cfqd = e->elevator_data; \
2296 unsigned int __data; \
2297 int ret = cfq_var_store(&__data, (page), count); \
2298 if (__data < (MIN)) \
2300 else if (__data > (MAX)) \
2303 *(__PTR) = msecs_to_jiffies(__data); \
2305 *(__PTR) = __data; \
2308 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
2309 STORE_FUNCTION(cfq_queued_store
, &cfqd
->cfq_queued
, 1, UINT_MAX
, 0);
2310 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1, UINT_MAX
, 1);
2311 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1, UINT_MAX
, 1);
2312 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
2313 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1, UINT_MAX
, 0);
2314 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
2315 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
2316 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
2317 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1, UINT_MAX
, 0);
2318 #undef STORE_FUNCTION
2320 #define CFQ_ATTR(name) \
2321 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2323 static struct elv_fs_entry cfq_attrs
[] = {
2326 CFQ_ATTR(fifo_expire_sync
),
2327 CFQ_ATTR(fifo_expire_async
),
2328 CFQ_ATTR(back_seek_max
),
2329 CFQ_ATTR(back_seek_penalty
),
2330 CFQ_ATTR(slice_sync
),
2331 CFQ_ATTR(slice_async
),
2332 CFQ_ATTR(slice_async_rq
),
2333 CFQ_ATTR(slice_idle
),
2337 static struct elevator_type iosched_cfq
= {
2339 .elevator_merge_fn
= cfq_merge
,
2340 .elevator_merged_fn
= cfq_merged_request
,
2341 .elevator_merge_req_fn
= cfq_merged_requests
,
2342 .elevator_dispatch_fn
= cfq_dispatch_requests
,
2343 .elevator_add_req_fn
= cfq_insert_request
,
2344 .elevator_activate_req_fn
= cfq_activate_request
,
2345 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
2346 .elevator_queue_empty_fn
= cfq_queue_empty
,
2347 .elevator_completed_req_fn
= cfq_completed_request
,
2348 .elevator_former_req_fn
= cfq_former_request
,
2349 .elevator_latter_req_fn
= cfq_latter_request
,
2350 .elevator_set_req_fn
= cfq_set_request
,
2351 .elevator_put_req_fn
= cfq_put_request
,
2352 .elevator_may_queue_fn
= cfq_may_queue
,
2353 .elevator_init_fn
= cfq_init_queue
,
2354 .elevator_exit_fn
= cfq_exit_queue
,
2357 .elevator_attrs
= cfq_attrs
,
2358 .elevator_name
= "cfq",
2359 .elevator_owner
= THIS_MODULE
,
2362 static int __init
cfq_init(void)
2367 * could be 0 on HZ < 1000 setups
2369 if (!cfq_slice_async
)
2370 cfq_slice_async
= 1;
2371 if (!cfq_slice_idle
)
2374 if (cfq_slab_setup())
2377 ret
= elv_register(&iosched_cfq
);
2384 static void __exit
cfq_exit(void)
2386 DECLARE_COMPLETION(all_gone
);
2387 elv_unregister(&iosched_cfq
);
2388 ioc_gone
= &all_gone
;
2389 /* ioc_gone's update must be visible before reading ioc_count */
2391 if (atomic_read(&ioc_count
))
2392 wait_for_completion(ioc_gone
);
2397 module_init(cfq_init
);
2398 module_exit(cfq_exit
);
2400 MODULE_AUTHOR("Jens Axboe");
2401 MODULE_LICENSE("GPL");
2402 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");