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-rw-r--r--block/cfq-iosched.c2428
1 files changed, 2428 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
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1/*
2 * linux/drivers/block/cfq-iosched.c
3 *
4 * CFQ, or complete fairness queueing, disk scheduler.
5 *
6 * Based on ideas from a previously unfinished io
7 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
8 *
9 * Copyright (C) 2003 Jens Axboe <axboe@suse.de>
10 */
11#include <linux/kernel.h>
12#include <linux/fs.h>
13#include <linux/blkdev.h>
14#include <linux/elevator.h>
15#include <linux/bio.h>
16#include <linux/config.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/init.h>
20#include <linux/compiler.h>
21#include <linux/hash.h>
22#include <linux/rbtree.h>
23#include <linux/mempool.h>
24#include <linux/ioprio.h>
25#include <linux/writeback.h>
26
27/*
28 * tunables
29 */
30static int cfq_quantum = 4; /* max queue in one round of service */
31static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
32static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
33static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
34static int cfq_back_penalty = 2; /* penalty of a backwards seek */
35
36static int cfq_slice_sync = HZ / 10;
37static int cfq_slice_async = HZ / 25;
38static int cfq_slice_async_rq = 2;
39static int cfq_slice_idle = HZ / 100;
40
41#define CFQ_IDLE_GRACE (HZ / 10)
42#define CFQ_SLICE_SCALE (5)
43
44#define CFQ_KEY_ASYNC (0)
45#define CFQ_KEY_ANY (0xffff)
46
47/*
48 * disable queueing at the driver/hardware level
49 */
50static int cfq_max_depth = 2;
51
52/*
53 * for the hash of cfqq inside the cfqd
54 */
55#define CFQ_QHASH_SHIFT 6
56#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
57#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
58
59/*
60 * for the hash of crq inside the cfqq
61 */
62#define CFQ_MHASH_SHIFT 6
63#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
64#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
65#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
66#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
67#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
68
69#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
70#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
71
72#define RQ_DATA(rq) (rq)->elevator_private
73
74/*
75 * rb-tree defines
76 */
77#define RB_NONE (2)
78#define RB_EMPTY(node) ((node)->rb_node == NULL)
79#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
80#define RB_CLEAR(node) do { \
81 (node)->rb_parent = NULL; \
82 RB_CLEAR_COLOR((node)); \
83 (node)->rb_right = NULL; \
84 (node)->rb_left = NULL; \
85} while (0)
86#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
87#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
88#define rq_rb_key(rq) (rq)->sector
89
90static kmem_cache_t *crq_pool;
91static kmem_cache_t *cfq_pool;
92static kmem_cache_t *cfq_ioc_pool;
93
94#define CFQ_PRIO_LISTS IOPRIO_BE_NR
95#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
96#define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
97#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
98
99#define ASYNC (0)
100#define SYNC (1)
101
102#define cfq_cfqq_dispatched(cfqq) \
103 ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
104
105#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
106
107#define cfq_cfqq_sync(cfqq) \
108 (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
109
110/*
111 * Per block device queue structure
112 */
113struct cfq_data {
114 atomic_t ref;
115 request_queue_t *queue;
116
117 /*
118 * rr list of queues with requests and the count of them
119 */
120 struct list_head rr_list[CFQ_PRIO_LISTS];
121 struct list_head busy_rr;
122 struct list_head cur_rr;
123 struct list_head idle_rr;
124 unsigned int busy_queues;
125
126 /*
127 * non-ordered list of empty cfqq's
128 */
129 struct list_head empty_list;
130
131 /*
132 * cfqq lookup hash
133 */
134 struct hlist_head *cfq_hash;
135
136 /*
137 * global crq hash for all queues
138 */
139 struct hlist_head *crq_hash;
140
141 unsigned int max_queued;
142
143 mempool_t *crq_pool;
144
145 int rq_in_driver;
146
147 /*
148 * schedule slice state info
149 */
150 /*
151 * idle window management
152 */
153 struct timer_list idle_slice_timer;
154 struct work_struct unplug_work;
155
156 struct cfq_queue *active_queue;
157 struct cfq_io_context *active_cic;
158 int cur_prio, cur_end_prio;
159 unsigned int dispatch_slice;
160
161 struct timer_list idle_class_timer;
162
163 sector_t last_sector;
164 unsigned long last_end_request;
165
166 unsigned int rq_starved;
167
168 /*
169 * tunables, see top of file
170 */
171 unsigned int cfq_quantum;
172 unsigned int cfq_queued;
173 unsigned int cfq_fifo_expire[2];
174 unsigned int cfq_back_penalty;
175 unsigned int cfq_back_max;
176 unsigned int cfq_slice[2];
177 unsigned int cfq_slice_async_rq;
178 unsigned int cfq_slice_idle;
179 unsigned int cfq_max_depth;
180};
181
182/*
183 * Per process-grouping structure
184 */
185struct cfq_queue {
186 /* reference count */
187 atomic_t ref;
188 /* parent cfq_data */
189 struct cfq_data *cfqd;
190 /* cfqq lookup hash */
191 struct hlist_node cfq_hash;
192 /* hash key */
193 unsigned int key;
194 /* on either rr or empty list of cfqd */
195 struct list_head cfq_list;
196 /* sorted list of pending requests */
197 struct rb_root sort_list;
198 /* if fifo isn't expired, next request to serve */
199 struct cfq_rq *next_crq;
200 /* requests queued in sort_list */
201 int queued[2];
202 /* currently allocated requests */
203 int allocated[2];
204 /* fifo list of requests in sort_list */
205 struct list_head fifo;
206
207 unsigned long slice_start;
208 unsigned long slice_end;
209 unsigned long slice_left;
210 unsigned long service_last;
211
212 /* number of requests that are on the dispatch list */
213 int on_dispatch[2];
214
215 /* io prio of this group */
216 unsigned short ioprio, org_ioprio;
217 unsigned short ioprio_class, org_ioprio_class;
218
219 /* various state flags, see below */
220 unsigned int flags;
221};
222
223struct cfq_rq {
224 struct rb_node rb_node;
225 sector_t rb_key;
226 struct request *request;
227 struct hlist_node hash;
228
229 struct cfq_queue *cfq_queue;
230 struct cfq_io_context *io_context;
231
232 unsigned int crq_flags;
233};
234
235enum cfqq_state_flags {
236 CFQ_CFQQ_FLAG_on_rr = 0,
237 CFQ_CFQQ_FLAG_wait_request,
238 CFQ_CFQQ_FLAG_must_alloc,
239 CFQ_CFQQ_FLAG_must_alloc_slice,
240 CFQ_CFQQ_FLAG_must_dispatch,
241 CFQ_CFQQ_FLAG_fifo_expire,
242 CFQ_CFQQ_FLAG_idle_window,
243 CFQ_CFQQ_FLAG_prio_changed,
244 CFQ_CFQQ_FLAG_expired,
245};
246
247#define CFQ_CFQQ_FNS(name) \
248static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
249{ \
250 cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
251} \
252static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
253{ \
254 cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
255} \
256static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
257{ \
258 return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
259}
260
261CFQ_CFQQ_FNS(on_rr);
262CFQ_CFQQ_FNS(wait_request);
263CFQ_CFQQ_FNS(must_alloc);
264CFQ_CFQQ_FNS(must_alloc_slice);
265CFQ_CFQQ_FNS(must_dispatch);
266CFQ_CFQQ_FNS(fifo_expire);
267CFQ_CFQQ_FNS(idle_window);
268CFQ_CFQQ_FNS(prio_changed);
269CFQ_CFQQ_FNS(expired);
270#undef CFQ_CFQQ_FNS
271
272enum cfq_rq_state_flags {
273 CFQ_CRQ_FLAG_is_sync = 0,
274};
275
276#define CFQ_CRQ_FNS(name) \
277static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
278{ \
279 crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
280} \
281static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
282{ \
283 crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
284} \
285static inline int cfq_crq_##name(const struct cfq_rq *crq) \
286{ \
287 return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
288}
289
290CFQ_CRQ_FNS(is_sync);
291#undef CFQ_CRQ_FNS
292
293static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
294static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
295static void cfq_put_cfqd(struct cfq_data *cfqd);
296
297#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
298
299/*
300 * lots of deadline iosched dupes, can be abstracted later...
301 */
302static inline void cfq_del_crq_hash(struct cfq_rq *crq)
303{
304 hlist_del_init(&crq->hash);
305}
306
307static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
308{
309 const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
310
311 hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
312}
313
314static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
315{
316 struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
317 struct hlist_node *entry, *next;
318
319 hlist_for_each_safe(entry, next, hash_list) {
320 struct cfq_rq *crq = list_entry_hash(entry);
321 struct request *__rq = crq->request;
322
323 if (!rq_mergeable(__rq)) {
324 cfq_del_crq_hash(crq);
325 continue;
326 }
327
328 if (rq_hash_key(__rq) == offset)
329 return __rq;
330 }
331
332 return NULL;
333}
334
335/*
336 * scheduler run of queue, if there are requests pending and no one in the
337 * driver that will restart queueing
338 */
339static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
340{
341 if (!cfqd->rq_in_driver && cfqd->busy_queues)
342 kblockd_schedule_work(&cfqd->unplug_work);
343}
344
345static int cfq_queue_empty(request_queue_t *q)
346{
347 struct cfq_data *cfqd = q->elevator->elevator_data;
348
349 return !cfqd->busy_queues;
350}
351
352/*
353 * Lifted from AS - choose which of crq1 and crq2 that is best served now.
354 * We choose the request that is closest to the head right now. Distance
355 * behind the head are penalized and only allowed to a certain extent.
356 */
357static struct cfq_rq *
358cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
359{
360 sector_t last, s1, s2, d1 = 0, d2 = 0;
361 int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
362 unsigned long back_max;
363
364 if (crq1 == NULL || crq1 == crq2)
365 return crq2;
366 if (crq2 == NULL)
367 return crq1;
368
369 if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
370 return crq1;
371 else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
372 return crq2;
373
374 s1 = crq1->request->sector;
375 s2 = crq2->request->sector;
376
377 last = cfqd->last_sector;
378
379 /*
380 * by definition, 1KiB is 2 sectors
381 */
382 back_max = cfqd->cfq_back_max * 2;
383
384 /*
385 * Strict one way elevator _except_ in the case where we allow
386 * short backward seeks which are biased as twice the cost of a
387 * similar forward seek.
388 */
389 if (s1 >= last)
390 d1 = s1 - last;
391 else if (s1 + back_max >= last)
392 d1 = (last - s1) * cfqd->cfq_back_penalty;
393 else
394 r1_wrap = 1;
395
396 if (s2 >= last)
397 d2 = s2 - last;
398 else if (s2 + back_max >= last)
399 d2 = (last - s2) * cfqd->cfq_back_penalty;
400 else
401 r2_wrap = 1;
402
403 /* Found required data */
404 if (!r1_wrap && r2_wrap)
405 return crq1;
406 else if (!r2_wrap && r1_wrap)
407 return crq2;
408 else if (r1_wrap && r2_wrap) {
409 /* both behind the head */
410 if (s1 <= s2)
411 return crq1;
412 else
413 return crq2;
414 }
415
416 /* Both requests in front of the head */
417 if (d1 < d2)
418 return crq1;
419 else if (d2 < d1)
420 return crq2;
421 else {
422 if (s1 >= s2)
423 return crq1;
424 else
425 return crq2;
426 }
427}
428
429/*
430 * would be nice to take fifo expire time into account as well
431 */
432static struct cfq_rq *
433cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
434 struct cfq_rq *last)
435{
436 struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
437 struct rb_node *rbnext, *rbprev;
438
439 if (!(rbnext = rb_next(&last->rb_node))) {
440 rbnext = rb_first(&cfqq->sort_list);
441 if (rbnext == &last->rb_node)
442 rbnext = NULL;
443 }
444
445 rbprev = rb_prev(&last->rb_node);
446
447 if (rbprev)
448 crq_prev = rb_entry_crq(rbprev);
449 if (rbnext)
450 crq_next = rb_entry_crq(rbnext);
451
452 return cfq_choose_req(cfqd, crq_next, crq_prev);
453}
454
455static void cfq_update_next_crq(struct cfq_rq *crq)
456{
457 struct cfq_queue *cfqq = crq->cfq_queue;
458
459 if (cfqq->next_crq == crq)
460 cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
461}
462
463static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
464{
465 struct cfq_data *cfqd = cfqq->cfqd;
466 struct list_head *list, *entry;
467
468 BUG_ON(!cfq_cfqq_on_rr(cfqq));
469
470 list_del(&cfqq->cfq_list);
471
472 if (cfq_class_rt(cfqq))
473 list = &cfqd->cur_rr;
474 else if (cfq_class_idle(cfqq))
475 list = &cfqd->idle_rr;
476 else {
477 /*
478 * if cfqq has requests in flight, don't allow it to be
479 * found in cfq_set_active_queue before it has finished them.
480 * this is done to increase fairness between a process that
481 * has lots of io pending vs one that only generates one
482 * sporadically or synchronously
483 */
484 if (cfq_cfqq_dispatched(cfqq))
485 list = &cfqd->busy_rr;
486 else
487 list = &cfqd->rr_list[cfqq->ioprio];
488 }
489
490 /*
491 * if queue was preempted, just add to front to be fair. busy_rr
492 * isn't sorted.
493 */
494 if (preempted || list == &cfqd->busy_rr) {
495 list_add(&cfqq->cfq_list, list);
496 return;
497 }
498
499 /*
500 * sort by when queue was last serviced
501 */
502 entry = list;
503 while ((entry = entry->prev) != list) {
504 struct cfq_queue *__cfqq = list_entry_cfqq(entry);
505
506 if (!__cfqq->service_last)
507 break;
508 if (time_before(__cfqq->service_last, cfqq->service_last))
509 break;
510 }
511
512 list_add(&cfqq->cfq_list, entry);
513}
514
515/*
516 * add to busy list of queues for service, trying to be fair in ordering
517 * the pending list according to last request service
518 */
519static inline void
520cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
521{
522 BUG_ON(cfq_cfqq_on_rr(cfqq));
523 cfq_mark_cfqq_on_rr(cfqq);
524 cfqd->busy_queues++;
525
526 cfq_resort_rr_list(cfqq, 0);
527}
528
529static inline void
530cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
531{
532 BUG_ON(!cfq_cfqq_on_rr(cfqq));
533 cfq_clear_cfqq_on_rr(cfqq);
534 list_move(&cfqq->cfq_list, &cfqd->empty_list);
535
536 BUG_ON(!cfqd->busy_queues);
537 cfqd->busy_queues--;
538}
539
540/*
541 * rb tree support functions
542 */
543static inline void cfq_del_crq_rb(struct cfq_rq *crq)
544{
545 struct cfq_queue *cfqq = crq->cfq_queue;
546 struct cfq_data *cfqd = cfqq->cfqd;
547 const int sync = cfq_crq_is_sync(crq);
548
549 BUG_ON(!cfqq->queued[sync]);
550 cfqq->queued[sync]--;
551
552 cfq_update_next_crq(crq);
553
554 rb_erase(&crq->rb_node, &cfqq->sort_list);
555 RB_CLEAR_COLOR(&crq->rb_node);
556
557 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
558 cfq_del_cfqq_rr(cfqd, cfqq);
559}
560
561static struct cfq_rq *
562__cfq_add_crq_rb(struct cfq_rq *crq)
563{
564 struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
565 struct rb_node *parent = NULL;
566 struct cfq_rq *__crq;
567
568 while (*p) {
569 parent = *p;
570 __crq = rb_entry_crq(parent);
571
572 if (crq->rb_key < __crq->rb_key)
573 p = &(*p)->rb_left;
574 else if (crq->rb_key > __crq->rb_key)
575 p = &(*p)->rb_right;
576 else
577 return __crq;
578 }
579
580 rb_link_node(&crq->rb_node, parent, p);
581 return NULL;
582}
583
584static void cfq_add_crq_rb(struct cfq_rq *crq)
585{
586 struct cfq_queue *cfqq = crq->cfq_queue;
587 struct cfq_data *cfqd = cfqq->cfqd;
588 struct request *rq = crq->request;
589 struct cfq_rq *__alias;
590
591 crq->rb_key = rq_rb_key(rq);
592 cfqq->queued[cfq_crq_is_sync(crq)]++;
593
594 /*
595 * looks a little odd, but the first insert might return an alias.
596 * if that happens, put the alias on the dispatch list
597 */
598 while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
599 cfq_dispatch_insert(cfqd->queue, __alias);
600
601 rb_insert_color(&crq->rb_node, &cfqq->sort_list);
602
603 if (!cfq_cfqq_on_rr(cfqq))
604 cfq_add_cfqq_rr(cfqd, cfqq);
605
606 /*
607 * check if this request is a better next-serve candidate
608 */
609 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
610}
611
612static inline void
613cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
614{
615 rb_erase(&crq->rb_node, &cfqq->sort_list);
616 cfqq->queued[cfq_crq_is_sync(crq)]--;
617
618 cfq_add_crq_rb(crq);
619}
620
621static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
622
623{
624 struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
625 struct rb_node *n;
626
627 if (!cfqq)
628 goto out;
629
630 n = cfqq->sort_list.rb_node;
631 while (n) {
632 struct cfq_rq *crq = rb_entry_crq(n);
633
634 if (sector < crq->rb_key)
635 n = n->rb_left;
636 else if (sector > crq->rb_key)
637 n = n->rb_right;
638 else
639 return crq->request;
640 }
641
642out:
643 return NULL;
644}
645
646static void cfq_activate_request(request_queue_t *q, struct request *rq)
647{
648 struct cfq_data *cfqd = q->elevator->elevator_data;
649
650 cfqd->rq_in_driver++;
651}
652
653static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
654{
655 struct cfq_data *cfqd = q->elevator->elevator_data;
656
657 WARN_ON(!cfqd->rq_in_driver);
658 cfqd->rq_in_driver--;
659}
660
661static void cfq_remove_request(struct request *rq)
662{
663 struct cfq_rq *crq = RQ_DATA(rq);
664
665 list_del_init(&rq->queuelist);
666 cfq_del_crq_rb(crq);
667 cfq_del_crq_hash(crq);
668}
669
670static int
671cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
672{
673 struct cfq_data *cfqd = q->elevator->elevator_data;
674 struct request *__rq;
675 int ret;
676
677 __rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
678 if (__rq && elv_rq_merge_ok(__rq, bio)) {
679 ret = ELEVATOR_BACK_MERGE;
680 goto out;
681 }
682
683 __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
684 if (__rq && elv_rq_merge_ok(__rq, bio)) {
685 ret = ELEVATOR_FRONT_MERGE;
686 goto out;
687 }
688
689 return ELEVATOR_NO_MERGE;
690out:
691 *req = __rq;
692 return ret;
693}
694
695static void cfq_merged_request(request_queue_t *q, struct request *req)
696{
697 struct cfq_data *cfqd = q->elevator->elevator_data;
698 struct cfq_rq *crq = RQ_DATA(req);
699
700 cfq_del_crq_hash(crq);
701 cfq_add_crq_hash(cfqd, crq);
702
703 if (rq_rb_key(req) != crq->rb_key) {
704 struct cfq_queue *cfqq = crq->cfq_queue;
705
706 cfq_update_next_crq(crq);
707 cfq_reposition_crq_rb(cfqq, crq);
708 }
709}
710
711static void
712cfq_merged_requests(request_queue_t *q, struct request *rq,
713 struct request *next)
714{
715 cfq_merged_request(q, rq);
716
717 /*
718 * reposition in fifo if next is older than rq
719 */
720 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
721 time_before(next->start_time, rq->start_time))
722 list_move(&rq->queuelist, &next->queuelist);
723
724 cfq_remove_request(next);
725}
726
727static inline void
728__cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
729{
730 if (cfqq) {
731 /*
732 * stop potential idle class queues waiting service
733 */
734 del_timer(&cfqd->idle_class_timer);
735
736 cfqq->slice_start = jiffies;
737 cfqq->slice_end = 0;
738 cfqq->slice_left = 0;
739 cfq_clear_cfqq_must_alloc_slice(cfqq);
740 cfq_clear_cfqq_fifo_expire(cfqq);
741 cfq_clear_cfqq_expired(cfqq);
742 }
743
744 cfqd->active_queue = cfqq;
745}
746
747/*
748 * 0
749 * 0,1
750 * 0,1,2
751 * 0,1,2,3
752 * 0,1,2,3,4
753 * 0,1,2,3,4,5
754 * 0,1,2,3,4,5,6
755 * 0,1,2,3,4,5,6,7
756 */
757static int cfq_get_next_prio_level(struct cfq_data *cfqd)
758{
759 int prio, wrap;
760
761 prio = -1;
762 wrap = 0;
763 do {
764 int p;
765
766 for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) {
767 if (!list_empty(&cfqd->rr_list[p])) {
768 prio = p;
769 break;
770 }
771 }
772
773 if (prio != -1)
774 break;
775 cfqd->cur_prio = 0;
776 if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
777 cfqd->cur_end_prio = 0;
778 if (wrap)
779 break;
780 wrap = 1;
781 }
782 } while (1);
783
784 if (unlikely(prio == -1))
785 return -1;
786
787 BUG_ON(prio >= CFQ_PRIO_LISTS);
788
789 list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr);
790
791 cfqd->cur_prio = prio + 1;
792 if (cfqd->cur_prio > cfqd->cur_end_prio) {
793 cfqd->cur_end_prio = cfqd->cur_prio;
794 cfqd->cur_prio = 0;
795 }
796 if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
797 cfqd->cur_prio = 0;
798 cfqd->cur_end_prio = 0;
799 }
800
801 return prio;
802}
803
804static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
805{
806 struct cfq_queue *cfqq;
807
808 /*
809 * if current queue is expired but not done with its requests yet,
810 * wait for that to happen
811 */
812 if ((cfqq = cfqd->active_queue) != NULL) {
813 if (cfq_cfqq_expired(cfqq) && cfq_cfqq_dispatched(cfqq))
814 return NULL;
815 }
816
817 /*
818 * if current list is non-empty, grab first entry. if it is empty,
819 * get next prio level and grab first entry then if any are spliced
820 */
821 if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
822 cfqq = list_entry_cfqq(cfqd->cur_rr.next);
823
824 /*
825 * if we have idle queues and no rt or be queues had pending
826 * requests, either allow immediate service if the grace period
827 * has passed or arm the idle grace timer
828 */
829 if (!cfqq && !list_empty(&cfqd->idle_rr)) {
830 unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
831
832 if (time_after_eq(jiffies, end))
833 cfqq = list_entry_cfqq(cfqd->idle_rr.next);
834 else
835 mod_timer(&cfqd->idle_class_timer, end);
836 }
837
838 __cfq_set_active_queue(cfqd, cfqq);
839 return cfqq;
840}
841
842/*
843 * current cfqq expired its slice (or was too idle), select new one
844 */
845static void
846__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
847 int preempted)
848{
849 unsigned long now = jiffies;
850
851 if (cfq_cfqq_wait_request(cfqq))
852 del_timer(&cfqd->idle_slice_timer);
853
854 if (!preempted && !cfq_cfqq_dispatched(cfqq))
855 cfqq->service_last = now;
856
857 cfq_clear_cfqq_must_dispatch(cfqq);
858 cfq_clear_cfqq_wait_request(cfqq);
859
860 /*
861 * store what was left of this slice, if the queue idled out
862 * or was preempted
863 */
864 if (time_after(now, cfqq->slice_end))
865 cfqq->slice_left = now - cfqq->slice_end;
866 else
867 cfqq->slice_left = 0;
868
869 if (cfq_cfqq_on_rr(cfqq))
870 cfq_resort_rr_list(cfqq, preempted);
871
872 if (cfqq == cfqd->active_queue)
873 cfqd->active_queue = NULL;
874
875 if (cfqd->active_cic) {
876 put_io_context(cfqd->active_cic->ioc);
877 cfqd->active_cic = NULL;
878 }
879
880 cfqd->dispatch_slice = 0;
881}
882
883static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
884{
885 struct cfq_queue *cfqq = cfqd->active_queue;
886
887 if (cfqq) {
888 /*
889 * use deferred expiry, if there are requests in progress as
890 * not to disturb the slice of the next queue
891 */
892 if (cfq_cfqq_dispatched(cfqq))
893 cfq_mark_cfqq_expired(cfqq);
894 else
895 __cfq_slice_expired(cfqd, cfqq, preempted);
896 }
897}
898
899static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
900
901{
902 WARN_ON(!RB_EMPTY(&cfqq->sort_list));
903 WARN_ON(cfqq != cfqd->active_queue);
904
905 /*
906 * idle is disabled, either manually or by past process history
907 */
908 if (!cfqd->cfq_slice_idle)
909 return 0;
910 if (!cfq_cfqq_idle_window(cfqq))
911 return 0;
912 /*
913 * task has exited, don't wait
914 */
915 if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
916 return 0;
917
918 cfq_mark_cfqq_must_dispatch(cfqq);
919 cfq_mark_cfqq_wait_request(cfqq);
920
921 if (!timer_pending(&cfqd->idle_slice_timer)) {
922 unsigned long slice_left = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
923
924 cfqd->idle_slice_timer.expires = jiffies + slice_left;
925 add_timer(&cfqd->idle_slice_timer);
926 }
927
928 return 1;
929}
930
931static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
932{
933 struct cfq_data *cfqd = q->elevator->elevator_data;
934 struct cfq_queue *cfqq = crq->cfq_queue;
935
936 cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
937 cfq_remove_request(crq->request);
938 cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
939 elv_dispatch_sort(q, crq->request);
940}
941
942/*
943 * return expired entry, or NULL to just start from scratch in rbtree
944 */
945static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
946{
947 struct cfq_data *cfqd = cfqq->cfqd;
948 struct request *rq;
949 struct cfq_rq *crq;
950
951 if (cfq_cfqq_fifo_expire(cfqq))
952 return NULL;
953
954 if (!list_empty(&cfqq->fifo)) {
955 int fifo = cfq_cfqq_class_sync(cfqq);
956
957 crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next));
958 rq = crq->request;
959 if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
960 cfq_mark_cfqq_fifo_expire(cfqq);
961 return crq;
962 }
963 }
964
965 return NULL;
966}
967
968/*
969 * Scale schedule slice based on io priority. Use the sync time slice only
970 * if a queue is marked sync and has sync io queued. A sync queue with async
971 * io only, should not get full sync slice length.
972 */
973static inline int
974cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
975{
976 const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)];
977
978 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
979
980 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio));
981}
982
983static inline void
984cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
985{
986 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
987}
988
989static inline int
990cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
991{
992 const int base_rq = cfqd->cfq_slice_async_rq;
993
994 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
995
996 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
997}
998
999/*
1000 * get next queue for service
1001 */
1002static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
1003{
1004 unsigned long now = jiffies;
1005 struct cfq_queue *cfqq;
1006
1007 cfqq = cfqd->active_queue;
1008 if (!cfqq)
1009 goto new_queue;
1010
1011 if (cfq_cfqq_expired(cfqq))
1012 goto new_queue;
1013
1014 /*
1015 * slice has expired
1016 */
1017 if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end))
1018 goto expire;
1019
1020 /*
1021 * if queue has requests, dispatch one. if not, check if
1022 * enough slice is left to wait for one
1023 */
1024 if (!RB_EMPTY(&cfqq->sort_list))
1025 goto keep_queue;
1026 else if (!force && cfq_cfqq_class_sync(cfqq) &&
1027 time_before(now, cfqq->slice_end)) {
1028 if (cfq_arm_slice_timer(cfqd, cfqq))
1029 return NULL;
1030 }
1031
1032expire:
1033 cfq_slice_expired(cfqd, 0);
1034new_queue:
1035 cfqq = cfq_set_active_queue(cfqd);
1036keep_queue:
1037 return cfqq;
1038}
1039
1040static int
1041__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1042 int max_dispatch)
1043{
1044 int dispatched = 0;
1045
1046 BUG_ON(RB_EMPTY(&cfqq->sort_list));
1047
1048 do {
1049 struct cfq_rq *crq;
1050
1051 /*
1052 * follow expired path, else get first next available
1053 */
1054 if ((crq = cfq_check_fifo(cfqq)) == NULL)
1055 crq = cfqq->next_crq;
1056
1057 /*
1058 * finally, insert request into driver dispatch list
1059 */
1060 cfq_dispatch_insert(cfqd->queue, crq);
1061
1062 cfqd->dispatch_slice++;
1063 dispatched++;
1064
1065 if (!cfqd->active_cic) {
1066 atomic_inc(&crq->io_context->ioc->refcount);
1067 cfqd->active_cic = crq->io_context;
1068 }
1069
1070 if (RB_EMPTY(&cfqq->sort_list))
1071 break;
1072
1073 } while (dispatched < max_dispatch);
1074
1075 /*
1076 * if slice end isn't set yet, set it. if at least one request was
1077 * sync, use the sync time slice value
1078 */
1079 if (!cfqq->slice_end)
1080 cfq_set_prio_slice(cfqd, cfqq);
1081
1082 /*
1083 * expire an async queue immediately if it has used up its slice. idle
1084 * queue always expire after 1 dispatch round.
1085 */
1086 if ((!cfq_cfqq_sync(cfqq) &&
1087 cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1088 cfq_class_idle(cfqq))
1089 cfq_slice_expired(cfqd, 0);
1090
1091 return dispatched;
1092}
1093
1094static int
1095cfq_dispatch_requests(request_queue_t *q, int force)
1096{
1097 struct cfq_data *cfqd = q->elevator->elevator_data;
1098 struct cfq_queue *cfqq;
1099
1100 if (!cfqd->busy_queues)
1101 return 0;
1102
1103 cfqq = cfq_select_queue(cfqd, force);
1104 if (cfqq) {
1105 int max_dispatch;
1106
1107 /*
1108 * if idle window is disabled, allow queue buildup
1109 */
1110 if (!cfq_cfqq_idle_window(cfqq) &&
1111 cfqd->rq_in_driver >= cfqd->cfq_max_depth)
1112 return 0;
1113
1114 cfq_clear_cfqq_must_dispatch(cfqq);
1115 cfq_clear_cfqq_wait_request(cfqq);
1116 del_timer(&cfqd->idle_slice_timer);
1117
1118 if (!force) {
1119 max_dispatch = cfqd->cfq_quantum;
1120 if (cfq_class_idle(cfqq))
1121 max_dispatch = 1;
1122 } else
1123 max_dispatch = INT_MAX;
1124
1125 return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
1126 }
1127
1128 return 0;
1129}
1130
1131/*
1132 * task holds one reference to the queue, dropped when task exits. each crq
1133 * in-flight on this queue also holds a reference, dropped when crq is freed.
1134 *
1135 * queue lock must be held here.
1136 */
1137static void cfq_put_queue(struct cfq_queue *cfqq)
1138{
1139 struct cfq_data *cfqd = cfqq->cfqd;
1140
1141 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1142
1143 if (!atomic_dec_and_test(&cfqq->ref))
1144 return;
1145
1146 BUG_ON(rb_first(&cfqq->sort_list));
1147 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1148 BUG_ON(cfq_cfqq_on_rr(cfqq));
1149
1150 if (unlikely(cfqd->active_queue == cfqq)) {
1151 __cfq_slice_expired(cfqd, cfqq, 0);
1152 cfq_schedule_dispatch(cfqd);
1153 }
1154
1155 cfq_put_cfqd(cfqq->cfqd);
1156
1157 /*
1158 * it's on the empty list and still hashed
1159 */
1160 list_del(&cfqq->cfq_list);
1161 hlist_del(&cfqq->cfq_hash);
1162 kmem_cache_free(cfq_pool, cfqq);
1163}
1164
1165static inline struct cfq_queue *
1166__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
1167 const int hashval)
1168{
1169 struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
1170 struct hlist_node *entry, *next;
1171
1172 hlist_for_each_safe(entry, next, hash_list) {
1173 struct cfq_queue *__cfqq = list_entry_qhash(entry);
1174 const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->ioprio_class, __cfqq->ioprio);
1175
1176 if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
1177 return __cfqq;
1178 }
1179
1180 return NULL;
1181}
1182
1183static struct cfq_queue *
1184cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
1185{
1186 return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
1187}
1188
1189static void cfq_free_io_context(struct cfq_io_context *cic)
1190{
1191 struct cfq_io_context *__cic;
1192 struct list_head *entry, *next;
1193
1194 list_for_each_safe(entry, next, &cic->list) {
1195 __cic = list_entry(entry, struct cfq_io_context, list);
1196 kmem_cache_free(cfq_ioc_pool, __cic);
1197 }
1198
1199 kmem_cache_free(cfq_ioc_pool, cic);
1200}
1201
1202/*
1203 * Called with interrupts disabled
1204 */
1205static void cfq_exit_single_io_context(struct cfq_io_context *cic)
1206{
1207 struct cfq_data *cfqd = cic->cfqq->cfqd;
1208 request_queue_t *q = cfqd->queue;
1209
1210 WARN_ON(!irqs_disabled());
1211
1212 spin_lock(q->queue_lock);
1213
1214 if (unlikely(cic->cfqq == cfqd->active_queue)) {
1215 __cfq_slice_expired(cfqd, cic->cfqq, 0);
1216 cfq_schedule_dispatch(cfqd);
1217 }
1218
1219 cfq_put_queue(cic->cfqq);
1220 cic->cfqq = NULL;
1221 spin_unlock(q->queue_lock);
1222}
1223
1224/*
1225 * Another task may update the task cic list, if it is doing a queue lookup
1226 * on its behalf. cfq_cic_lock excludes such concurrent updates
1227 */
1228static void cfq_exit_io_context(struct cfq_io_context *cic)
1229{
1230 struct cfq_io_context *__cic;
1231 struct list_head *entry;
1232 unsigned long flags;
1233
1234 local_irq_save(flags);
1235
1236 /*
1237 * put the reference this task is holding to the various queues
1238 */
1239 list_for_each(entry, &cic->list) {
1240 __cic = list_entry(entry, struct cfq_io_context, list);
1241 cfq_exit_single_io_context(__cic);
1242 }
1243
1244 cfq_exit_single_io_context(cic);
1245 local_irq_restore(flags);
1246}
1247
1248static struct cfq_io_context *
1249cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1250{
1251 struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
1252
1253 if (cic) {
1254 INIT_LIST_HEAD(&cic->list);
1255 cic->cfqq = NULL;
1256 cic->key = NULL;
1257 cic->last_end_request = jiffies;
1258 cic->ttime_total = 0;
1259 cic->ttime_samples = 0;
1260 cic->ttime_mean = 0;
1261 cic->dtor = cfq_free_io_context;
1262 cic->exit = cfq_exit_io_context;
1263 }
1264
1265 return cic;
1266}
1267
1268static void cfq_init_prio_data(struct cfq_queue *cfqq)
1269{
1270 struct task_struct *tsk = current;
1271 int ioprio_class;
1272
1273 if (!cfq_cfqq_prio_changed(cfqq))
1274 return;
1275
1276 ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
1277 switch (ioprio_class) {
1278 default:
1279 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1280 case IOPRIO_CLASS_NONE:
1281 /*
1282 * no prio set, place us in the middle of the BE classes
1283 */
1284 cfqq->ioprio = task_nice_ioprio(tsk);
1285 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1286 break;
1287 case IOPRIO_CLASS_RT:
1288 cfqq->ioprio = task_ioprio(tsk);
1289 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1290 break;
1291 case IOPRIO_CLASS_BE:
1292 cfqq->ioprio = task_ioprio(tsk);
1293 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1294 break;
1295 case IOPRIO_CLASS_IDLE:
1296 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1297 cfqq->ioprio = 7;
1298 cfq_clear_cfqq_idle_window(cfqq);
1299 break;
1300 }
1301
1302 /*
1303 * keep track of original prio settings in case we have to temporarily
1304 * elevate the priority of this queue
1305 */
1306 cfqq->org_ioprio = cfqq->ioprio;
1307 cfqq->org_ioprio_class = cfqq->ioprio_class;
1308
1309 if (cfq_cfqq_on_rr(cfqq))
1310 cfq_resort_rr_list(cfqq, 0);
1311
1312 cfq_clear_cfqq_prio_changed(cfqq);
1313}
1314
1315static inline void changed_ioprio(struct cfq_queue *cfqq)
1316{
1317 if (cfqq) {
1318 struct cfq_data *cfqd = cfqq->cfqd;
1319
1320 spin_lock(cfqd->queue->queue_lock);
1321 cfq_mark_cfqq_prio_changed(cfqq);
1322 cfq_init_prio_data(cfqq);
1323 spin_unlock(cfqd->queue->queue_lock);
1324 }
1325}
1326
1327/*
1328 * callback from sys_ioprio_set, irqs are disabled
1329 */
1330static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
1331{
1332 struct cfq_io_context *cic = ioc->cic;
1333
1334 changed_ioprio(cic->cfqq);
1335
1336 list_for_each_entry(cic, &cic->list, list)
1337 changed_ioprio(cic->cfqq);
1338
1339 return 0;
1340}
1341
1342static struct cfq_queue *
1343cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
1344 gfp_t gfp_mask)
1345{
1346 const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
1347 struct cfq_queue *cfqq, *new_cfqq = NULL;
1348
1349retry:
1350 cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
1351
1352 if (!cfqq) {
1353 if (new_cfqq) {
1354 cfqq = new_cfqq;
1355 new_cfqq = NULL;
1356 } else if (gfp_mask & __GFP_WAIT) {
1357 spin_unlock_irq(cfqd->queue->queue_lock);
1358 new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1359 spin_lock_irq(cfqd->queue->queue_lock);
1360 goto retry;
1361 } else {
1362 cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
1363 if (!cfqq)
1364 goto out;
1365 }
1366
1367 memset(cfqq, 0, sizeof(*cfqq));
1368
1369 INIT_HLIST_NODE(&cfqq->cfq_hash);
1370 INIT_LIST_HEAD(&cfqq->cfq_list);
1371 RB_CLEAR_ROOT(&cfqq->sort_list);
1372 INIT_LIST_HEAD(&cfqq->fifo);
1373
1374 cfqq->key = key;
1375 hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
1376 atomic_set(&cfqq->ref, 0);
1377 cfqq->cfqd = cfqd;
1378 atomic_inc(&cfqd->ref);
1379 cfqq->service_last = 0;
1380 /*
1381 * set ->slice_left to allow preemption for a new process
1382 */
1383 cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
1384 cfq_mark_cfqq_idle_window(cfqq);
1385 cfq_mark_cfqq_prio_changed(cfqq);
1386 cfq_init_prio_data(cfqq);
1387 }
1388
1389 if (new_cfqq)
1390 kmem_cache_free(cfq_pool, new_cfqq);
1391
1392 atomic_inc(&cfqq->ref);
1393out:
1394 WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
1395 return cfqq;
1396}
1397
1398/*
1399 * Setup general io context and cfq io context. There can be several cfq
1400 * io contexts per general io context, if this process is doing io to more
1401 * than one device managed by cfq. Note that caller is holding a reference to
1402 * cfqq, so we don't need to worry about it disappearing
1403 */
1404static struct cfq_io_context *
1405cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
1406{
1407 struct io_context *ioc = NULL;
1408 struct cfq_io_context *cic;
1409
1410 might_sleep_if(gfp_mask & __GFP_WAIT);
1411
1412 ioc = get_io_context(gfp_mask);
1413 if (!ioc)
1414 return NULL;
1415
1416 if ((cic = ioc->cic) == NULL) {
1417 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1418
1419 if (cic == NULL)
1420 goto err;
1421
1422 /*
1423 * manually increment generic io_context usage count, it
1424 * cannot go away since we are already holding one ref to it
1425 */
1426 ioc->cic = cic;
1427 ioc->set_ioprio = cfq_ioc_set_ioprio;
1428 cic->ioc = ioc;
1429 cic->key = cfqd;
1430 atomic_inc(&cfqd->ref);
1431 } else {
1432 struct cfq_io_context *__cic;
1433
1434 /*
1435 * the first cic on the list is actually the head itself
1436 */
1437 if (cic->key == cfqd)
1438 goto out;
1439
1440 /*
1441 * cic exists, check if we already are there. linear search
1442 * should be ok here, the list will usually not be more than
1443 * 1 or a few entries long
1444 */
1445 list_for_each_entry(__cic, &cic->list, list) {
1446 /*
1447 * this process is already holding a reference to
1448 * this queue, so no need to get one more
1449 */
1450 if (__cic->key == cfqd) {
1451 cic = __cic;
1452 goto out;
1453 }
1454 }
1455
1456 /*
1457 * nope, process doesn't have a cic assoicated with this
1458 * cfqq yet. get a new one and add to list
1459 */
1460 __cic = cfq_alloc_io_context(cfqd, gfp_mask);
1461 if (__cic == NULL)
1462 goto err;
1463
1464 __cic->ioc = ioc;
1465 __cic->key = cfqd;
1466 atomic_inc(&cfqd->ref);
1467 list_add(&__cic->list, &cic->list);
1468 cic = __cic;
1469 }
1470
1471out:
1472 return cic;
1473err:
1474 put_io_context(ioc);
1475 return NULL;
1476}
1477
1478static void
1479cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1480{
1481 unsigned long elapsed, ttime;
1482
1483 /*
1484 * if this context already has stuff queued, thinktime is from
1485 * last queue not last end
1486 */
1487#if 0
1488 if (time_after(cic->last_end_request, cic->last_queue))
1489 elapsed = jiffies - cic->last_end_request;
1490 else
1491 elapsed = jiffies - cic->last_queue;
1492#else
1493 elapsed = jiffies - cic->last_end_request;
1494#endif
1495
1496 ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1497
1498 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1499 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1500 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1501}
1502
1503#define sample_valid(samples) ((samples) > 80)
1504
1505/*
1506 * Disable idle window if the process thinks too long or seeks so much that
1507 * it doesn't matter
1508 */
1509static void
1510cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1511 struct cfq_io_context *cic)
1512{
1513 int enable_idle = cfq_cfqq_idle_window(cfqq);
1514
1515 if (!cic->ioc->task || !cfqd->cfq_slice_idle)
1516 enable_idle = 0;
1517 else if (sample_valid(cic->ttime_samples)) {
1518 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1519 enable_idle = 0;
1520 else
1521 enable_idle = 1;
1522 }
1523
1524 if (enable_idle)
1525 cfq_mark_cfqq_idle_window(cfqq);
1526 else
1527 cfq_clear_cfqq_idle_window(cfqq);
1528}
1529
1530
1531/*
1532 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1533 * no or if we aren't sure, a 1 will cause a preempt.
1534 */
1535static int
1536cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1537 struct cfq_rq *crq)
1538{
1539 struct cfq_queue *cfqq = cfqd->active_queue;
1540
1541 if (cfq_class_idle(new_cfqq))
1542 return 0;
1543
1544 if (!cfqq)
1545 return 1;
1546
1547 if (cfq_class_idle(cfqq))
1548 return 1;
1549 if (!cfq_cfqq_wait_request(new_cfqq))
1550 return 0;
1551 /*
1552 * if it doesn't have slice left, forget it
1553 */
1554 if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
1555 return 0;
1556 if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
1557 return 1;
1558
1559 return 0;
1560}
1561
1562/*
1563 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1564 * let it have half of its nominal slice.
1565 */
1566static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1567{
1568 struct cfq_queue *__cfqq, *next;
1569
1570 list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
1571 cfq_resort_rr_list(__cfqq, 1);
1572
1573 if (!cfqq->slice_left)
1574 cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
1575
1576 cfqq->slice_end = cfqq->slice_left + jiffies;
1577 __cfq_slice_expired(cfqd, cfqq, 1);
1578 __cfq_set_active_queue(cfqd, cfqq);
1579}
1580
1581/*
1582 * should really be a ll_rw_blk.c helper
1583 */
1584static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1585{
1586 request_queue_t *q = cfqd->queue;
1587
1588 if (!blk_queue_plugged(q))
1589 q->request_fn(q);
1590 else
1591 __generic_unplug_device(q);
1592}
1593
1594/*
1595 * Called when a new fs request (crq) is added (to cfqq). Check if there's
1596 * something we should do about it
1597 */
1598static void
1599cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1600 struct cfq_rq *crq)
1601{
1602 struct cfq_io_context *cic;
1603
1604 cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
1605
1606 /*
1607 * we never wait for an async request and we don't allow preemption
1608 * of an async request. so just return early
1609 */
1610 if (!cfq_crq_is_sync(crq))
1611 return;
1612
1613 cic = crq->io_context;
1614
1615 cfq_update_io_thinktime(cfqd, cic);
1616 cfq_update_idle_window(cfqd, cfqq, cic);
1617
1618 cic->last_queue = jiffies;
1619
1620 if (cfqq == cfqd->active_queue) {
1621 /*
1622 * if we are waiting for a request for this queue, let it rip
1623 * immediately and flag that we must not expire this queue
1624 * just now
1625 */
1626 if (cfq_cfqq_wait_request(cfqq)) {
1627 cfq_mark_cfqq_must_dispatch(cfqq);
1628 del_timer(&cfqd->idle_slice_timer);
1629 cfq_start_queueing(cfqd, cfqq);
1630 }
1631 } else if (cfq_should_preempt(cfqd, cfqq, crq)) {
1632 /*
1633 * not the active queue - expire current slice if it is
1634 * idle and has expired it's mean thinktime or this new queue
1635 * has some old slice time left and is of higher priority
1636 */
1637 cfq_preempt_queue(cfqd, cfqq);
1638 cfq_mark_cfqq_must_dispatch(cfqq);
1639 cfq_start_queueing(cfqd, cfqq);
1640 }
1641}
1642
1643static void cfq_insert_request(request_queue_t *q, struct request *rq)
1644{
1645 struct cfq_data *cfqd = q->elevator->elevator_data;
1646 struct cfq_rq *crq = RQ_DATA(rq);
1647 struct cfq_queue *cfqq = crq->cfq_queue;
1648
1649 cfq_init_prio_data(cfqq);
1650
1651 cfq_add_crq_rb(crq);
1652
1653 list_add_tail(&rq->queuelist, &cfqq->fifo);
1654
1655 if (rq_mergeable(rq))
1656 cfq_add_crq_hash(cfqd, crq);
1657
1658 cfq_crq_enqueued(cfqd, cfqq, crq);
1659}
1660
1661static void cfq_completed_request(request_queue_t *q, struct request *rq)
1662{
1663 struct cfq_rq *crq = RQ_DATA(rq);
1664 struct cfq_queue *cfqq = crq->cfq_queue;
1665 struct cfq_data *cfqd = cfqq->cfqd;
1666 const int sync = cfq_crq_is_sync(crq);
1667 unsigned long now;
1668
1669 now = jiffies;
1670
1671 WARN_ON(!cfqd->rq_in_driver);
1672 WARN_ON(!cfqq->on_dispatch[sync]);
1673 cfqd->rq_in_driver--;
1674 cfqq->on_dispatch[sync]--;
1675
1676 if (!cfq_class_idle(cfqq))
1677 cfqd->last_end_request = now;
1678
1679 if (!cfq_cfqq_dispatched(cfqq)) {
1680 if (cfq_cfqq_on_rr(cfqq)) {
1681 cfqq->service_last = now;
1682 cfq_resort_rr_list(cfqq, 0);
1683 }
1684 if (cfq_cfqq_expired(cfqq)) {
1685 __cfq_slice_expired(cfqd, cfqq, 0);
1686 cfq_schedule_dispatch(cfqd);
1687 }
1688 }
1689
1690 if (cfq_crq_is_sync(crq))
1691 crq->io_context->last_end_request = now;
1692}
1693
1694static struct request *
1695cfq_former_request(request_queue_t *q, struct request *rq)
1696{
1697 struct cfq_rq *crq = RQ_DATA(rq);
1698 struct rb_node *rbprev = rb_prev(&crq->rb_node);
1699
1700 if (rbprev)
1701 return rb_entry_crq(rbprev)->request;
1702
1703 return NULL;
1704}
1705
1706static struct request *
1707cfq_latter_request(request_queue_t *q, struct request *rq)
1708{
1709 struct cfq_rq *crq = RQ_DATA(rq);
1710 struct rb_node *rbnext = rb_next(&crq->rb_node);
1711
1712 if (rbnext)
1713 return rb_entry_crq(rbnext)->request;
1714
1715 return NULL;
1716}
1717
1718/*
1719 * we temporarily boost lower priority queues if they are holding fs exclusive
1720 * resources. they are boosted to normal prio (CLASS_BE/4)
1721 */
1722static void cfq_prio_boost(struct cfq_queue *cfqq)
1723{
1724 const int ioprio_class = cfqq->ioprio_class;
1725 const int ioprio = cfqq->ioprio;
1726
1727 if (has_fs_excl()) {
1728 /*
1729 * boost idle prio on transactions that would lock out other
1730 * users of the filesystem
1731 */
1732 if (cfq_class_idle(cfqq))
1733 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1734 if (cfqq->ioprio > IOPRIO_NORM)
1735 cfqq->ioprio = IOPRIO_NORM;
1736 } else {
1737 /*
1738 * check if we need to unboost the queue
1739 */
1740 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
1741 cfqq->ioprio_class = cfqq->org_ioprio_class;
1742 if (cfqq->ioprio != cfqq->org_ioprio)
1743 cfqq->ioprio = cfqq->org_ioprio;
1744 }
1745
1746 /*
1747 * refile between round-robin lists if we moved the priority class
1748 */
1749 if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) &&
1750 cfq_cfqq_on_rr(cfqq))
1751 cfq_resort_rr_list(cfqq, 0);
1752}
1753
1754static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
1755{
1756 if (rw == READ || process_sync(task))
1757 return task->pid;
1758
1759 return CFQ_KEY_ASYNC;
1760}
1761
1762static inline int
1763__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1764 struct task_struct *task, int rw)
1765{
1766#if 1
1767 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
1768 !cfq_cfqq_must_alloc_slice(cfqq)) {
1769 cfq_mark_cfqq_must_alloc_slice(cfqq);
1770 return ELV_MQUEUE_MUST;
1771 }
1772
1773 return ELV_MQUEUE_MAY;
1774#else
1775 if (!cfqq || task->flags & PF_MEMALLOC)
1776 return ELV_MQUEUE_MAY;
1777 if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) {
1778 if (cfq_cfqq_wait_request(cfqq))
1779 return ELV_MQUEUE_MUST;
1780
1781 /*
1782 * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
1783 * can quickly flood the queue with writes from a single task
1784 */
1785 if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) {
1786 cfq_mark_cfqq_must_alloc_slice(cfqq);
1787 return ELV_MQUEUE_MUST;
1788 }
1789
1790 return ELV_MQUEUE_MAY;
1791 }
1792 if (cfq_class_idle(cfqq))
1793 return ELV_MQUEUE_NO;
1794 if (cfqq->allocated[rw] >= cfqd->max_queued) {
1795 struct io_context *ioc = get_io_context(GFP_ATOMIC);
1796 int ret = ELV_MQUEUE_NO;
1797
1798 if (ioc && ioc->nr_batch_requests)
1799 ret = ELV_MQUEUE_MAY;
1800
1801 put_io_context(ioc);
1802 return ret;
1803 }
1804
1805 return ELV_MQUEUE_MAY;
1806#endif
1807}
1808
1809static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio)
1810{
1811 struct cfq_data *cfqd = q->elevator->elevator_data;
1812 struct task_struct *tsk = current;
1813 struct cfq_queue *cfqq;
1814
1815 /*
1816 * don't force setup of a queue from here, as a call to may_queue
1817 * does not necessarily imply that a request actually will be queued.
1818 * so just lookup a possibly existing queue, or return 'may queue'
1819 * if that fails
1820 */
1821 cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio);
1822 if (cfqq) {
1823 cfq_init_prio_data(cfqq);
1824 cfq_prio_boost(cfqq);
1825
1826 return __cfq_may_queue(cfqd, cfqq, tsk, rw);
1827 }
1828
1829 return ELV_MQUEUE_MAY;
1830}
1831
1832static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
1833{
1834 struct cfq_data *cfqd = q->elevator->elevator_data;
1835 struct request_list *rl = &q->rq;
1836
1837 if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) {
1838 smp_mb();
1839 if (waitqueue_active(&rl->wait[READ]))
1840 wake_up(&rl->wait[READ]);
1841 }
1842
1843 if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) {
1844 smp_mb();
1845 if (waitqueue_active(&rl->wait[WRITE]))
1846 wake_up(&rl->wait[WRITE]);
1847 }
1848}
1849
1850/*
1851 * queue lock held here
1852 */
1853static void cfq_put_request(request_queue_t *q, struct request *rq)
1854{
1855 struct cfq_data *cfqd = q->elevator->elevator_data;
1856 struct cfq_rq *crq = RQ_DATA(rq);
1857
1858 if (crq) {
1859 struct cfq_queue *cfqq = crq->cfq_queue;
1860 const int rw = rq_data_dir(rq);
1861
1862 BUG_ON(!cfqq->allocated[rw]);
1863 cfqq->allocated[rw]--;
1864
1865 put_io_context(crq->io_context->ioc);
1866
1867 mempool_free(crq, cfqd->crq_pool);
1868 rq->elevator_private = NULL;
1869
1870 cfq_check_waiters(q, cfqq);
1871 cfq_put_queue(cfqq);
1872 }
1873}
1874
1875/*
1876 * Allocate cfq data structures associated with this request.
1877 */
1878static int
1879cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
1880 gfp_t gfp_mask)
1881{
1882 struct cfq_data *cfqd = q->elevator->elevator_data;
1883 struct task_struct *tsk = current;
1884 struct cfq_io_context *cic;
1885 const int rw = rq_data_dir(rq);
1886 pid_t key = cfq_queue_pid(tsk, rw);
1887 struct cfq_queue *cfqq;
1888 struct cfq_rq *crq;
1889 unsigned long flags;
1890
1891 might_sleep_if(gfp_mask & __GFP_WAIT);
1892
1893 cic = cfq_get_io_context(cfqd, key, gfp_mask);
1894
1895 spin_lock_irqsave(q->queue_lock, flags);
1896
1897 if (!cic)
1898 goto queue_fail;
1899
1900 if (!cic->cfqq) {
1901 cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
1902 if (!cfqq)
1903 goto queue_fail;
1904
1905 cic->cfqq = cfqq;
1906 } else
1907 cfqq = cic->cfqq;
1908
1909 cfqq->allocated[rw]++;
1910 cfq_clear_cfqq_must_alloc(cfqq);
1911 cfqd->rq_starved = 0;
1912 atomic_inc(&cfqq->ref);
1913 spin_unlock_irqrestore(q->queue_lock, flags);
1914
1915 crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
1916 if (crq) {
1917 RB_CLEAR(&crq->rb_node);
1918 crq->rb_key = 0;
1919 crq->request = rq;
1920 INIT_HLIST_NODE(&crq->hash);
1921 crq->cfq_queue = cfqq;
1922 crq->io_context = cic;
1923
1924 if (rw == READ || process_sync(tsk))
1925 cfq_mark_crq_is_sync(crq);
1926 else
1927 cfq_clear_crq_is_sync(crq);
1928
1929 rq->elevator_private = crq;
1930 return 0;
1931 }
1932
1933 spin_lock_irqsave(q->queue_lock, flags);
1934 cfqq->allocated[rw]--;
1935 if (!(cfqq->allocated[0] + cfqq->allocated[1]))
1936 cfq_mark_cfqq_must_alloc(cfqq);
1937 cfq_put_queue(cfqq);
1938queue_fail:
1939 if (cic)
1940 put_io_context(cic->ioc);
1941 /*
1942 * mark us rq allocation starved. we need to kickstart the process
1943 * ourselves if there are no pending requests that can do it for us.
1944 * that would be an extremely rare OOM situation
1945 */
1946 cfqd->rq_starved = 1;
1947 cfq_schedule_dispatch(cfqd);
1948 spin_unlock_irqrestore(q->queue_lock, flags);
1949 return 1;
1950}
1951
1952static void cfq_kick_queue(void *data)
1953{
1954 request_queue_t *q = data;
1955 struct cfq_data *cfqd = q->elevator->elevator_data;
1956 unsigned long flags;
1957
1958 spin_lock_irqsave(q->queue_lock, flags);
1959
1960 if (cfqd->rq_starved) {
1961 struct request_list *rl = &q->rq;
1962
1963 /*
1964 * we aren't guaranteed to get a request after this, but we
1965 * have to be opportunistic
1966 */
1967 smp_mb();
1968 if (waitqueue_active(&rl->wait[READ]))
1969 wake_up(&rl->wait[READ]);
1970 if (waitqueue_active(&rl->wait[WRITE]))
1971 wake_up(&rl->wait[WRITE]);
1972 }
1973
1974 blk_remove_plug(q);
1975 q->request_fn(q);
1976 spin_unlock_irqrestore(q->queue_lock, flags);
1977}
1978
1979/*
1980 * Timer running if the active_queue is currently idling inside its time slice
1981 */
1982static void cfq_idle_slice_timer(unsigned long data)
1983{
1984 struct cfq_data *cfqd = (struct cfq_data *) data;
1985 struct cfq_queue *cfqq;
1986 unsigned long flags;
1987
1988 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1989
1990 if ((cfqq = cfqd->active_queue) != NULL) {
1991 unsigned long now = jiffies;
1992
1993 /*
1994 * expired
1995 */
1996 if (time_after(now, cfqq->slice_end))
1997 goto expire;
1998
1999 /*
2000 * only expire and reinvoke request handler, if there are
2001 * other queues with pending requests
2002 */
2003 if (!cfqd->busy_queues) {
2004 cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
2005 add_timer(&cfqd->idle_slice_timer);
2006 goto out_cont;
2007 }
2008
2009 /*
2010 * not expired and it has a request pending, let it dispatch
2011 */
2012 if (!RB_EMPTY(&cfqq->sort_list)) {
2013 cfq_mark_cfqq_must_dispatch(cfqq);
2014 goto out_kick;
2015 }
2016 }
2017expire:
2018 cfq_slice_expired(cfqd, 0);
2019out_kick:
2020 cfq_schedule_dispatch(cfqd);
2021out_cont:
2022 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2023}
2024
2025/*
2026 * Timer running if an idle class queue is waiting for service
2027 */
2028static void cfq_idle_class_timer(unsigned long data)
2029{
2030 struct cfq_data *cfqd = (struct cfq_data *) data;
2031 unsigned long flags, end;
2032
2033 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2034
2035 /*
2036 * race with a non-idle queue, reset timer
2037 */
2038 end = cfqd->last_end_request + CFQ_IDLE_GRACE;
2039 if (!time_after_eq(jiffies, end)) {
2040 cfqd->idle_class_timer.expires = end;
2041 add_timer(&cfqd->idle_class_timer);
2042 } else
2043 cfq_schedule_dispatch(cfqd);
2044
2045 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2046}
2047
2048static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2049{
2050 del_timer_sync(&cfqd->idle_slice_timer);
2051 del_timer_sync(&cfqd->idle_class_timer);
2052 blk_sync_queue(cfqd->queue);
2053}
2054
2055static void cfq_put_cfqd(struct cfq_data *cfqd)
2056{
2057 request_queue_t *q = cfqd->queue;
2058
2059 if (!atomic_dec_and_test(&cfqd->ref))
2060 return;
2061
2062 cfq_shutdown_timer_wq(cfqd);
2063 blk_put_queue(q);
2064
2065 mempool_destroy(cfqd->crq_pool);
2066 kfree(cfqd->crq_hash);
2067 kfree(cfqd->cfq_hash);
2068 kfree(cfqd);
2069}
2070
2071static void cfq_exit_queue(elevator_t *e)
2072{
2073 struct cfq_data *cfqd = e->elevator_data;
2074
2075 cfq_shutdown_timer_wq(cfqd);
2076 cfq_put_cfqd(cfqd);
2077}
2078
2079static int cfq_init_queue(request_queue_t *q, elevator_t *e)
2080{
2081 struct cfq_data *cfqd;
2082 int i;
2083
2084 cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
2085 if (!cfqd)
2086 return -ENOMEM;
2087
2088 memset(cfqd, 0, sizeof(*cfqd));
2089
2090 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2091 INIT_LIST_HEAD(&cfqd->rr_list[i]);
2092
2093 INIT_LIST_HEAD(&cfqd->busy_rr);
2094 INIT_LIST_HEAD(&cfqd->cur_rr);
2095 INIT_LIST_HEAD(&cfqd->idle_rr);
2096 INIT_LIST_HEAD(&cfqd->empty_list);
2097
2098 cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
2099 if (!cfqd->crq_hash)
2100 goto out_crqhash;
2101
2102 cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
2103 if (!cfqd->cfq_hash)
2104 goto out_cfqhash;
2105
2106 cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
2107 if (!cfqd->crq_pool)
2108 goto out_crqpool;
2109
2110 for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
2111 INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
2112 for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
2113 INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
2114
2115 e->elevator_data = cfqd;
2116
2117 cfqd->queue = q;
2118 atomic_inc(&q->refcnt);
2119
2120 cfqd->max_queued = q->nr_requests / 4;
2121 q->nr_batching = cfq_queued;
2122
2123 init_timer(&cfqd->idle_slice_timer);
2124 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2125 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2126
2127 init_timer(&cfqd->idle_class_timer);
2128 cfqd->idle_class_timer.function = cfq_idle_class_timer;
2129 cfqd->idle_class_timer.data = (unsigned long) cfqd;
2130
2131 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
2132
2133 atomic_set(&cfqd->ref, 1);
2134
2135 cfqd->cfq_queued = cfq_queued;
2136 cfqd->cfq_quantum = cfq_quantum;
2137 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2138 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2139 cfqd->cfq_back_max = cfq_back_max;
2140 cfqd->cfq_back_penalty = cfq_back_penalty;
2141 cfqd->cfq_slice[0] = cfq_slice_async;
2142 cfqd->cfq_slice[1] = cfq_slice_sync;
2143 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2144 cfqd->cfq_slice_idle = cfq_slice_idle;
2145 cfqd->cfq_max_depth = cfq_max_depth;
2146
2147 return 0;
2148out_crqpool:
2149 kfree(cfqd->cfq_hash);
2150out_cfqhash:
2151 kfree(cfqd->crq_hash);
2152out_crqhash:
2153 kfree(cfqd);
2154 return -ENOMEM;
2155}
2156
2157static void cfq_slab_kill(void)
2158{
2159 if (crq_pool)
2160 kmem_cache_destroy(crq_pool);
2161 if (cfq_pool)
2162 kmem_cache_destroy(cfq_pool);
2163 if (cfq_ioc_pool)
2164 kmem_cache_destroy(cfq_ioc_pool);
2165}
2166
2167static int __init cfq_slab_setup(void)
2168{
2169 crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
2170 NULL, NULL);
2171 if (!crq_pool)
2172 goto fail;
2173
2174 cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
2175 NULL, NULL);
2176 if (!cfq_pool)
2177 goto fail;
2178
2179 cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
2180 sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
2181 if (!cfq_ioc_pool)
2182 goto fail;
2183
2184 return 0;
2185fail:
2186 cfq_slab_kill();
2187 return -ENOMEM;
2188}
2189
2190/*
2191 * sysfs parts below -->
2192 */
2193struct cfq_fs_entry {
2194 struct attribute attr;
2195 ssize_t (*show)(struct cfq_data *, char *);
2196 ssize_t (*store)(struct cfq_data *, const char *, size_t);
2197};
2198
2199static ssize_t
2200cfq_var_show(unsigned int var, char *page)
2201{
2202 return sprintf(page, "%d\n", var);
2203}
2204
2205static ssize_t
2206cfq_var_store(unsigned int *var, const char *page, size_t count)
2207{
2208 char *p = (char *) page;
2209
2210 *var = simple_strtoul(p, &p, 10);
2211 return count;
2212}
2213
2214#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2215static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
2216{ \
2217 unsigned int __data = __VAR; \
2218 if (__CONV) \
2219 __data = jiffies_to_msecs(__data); \
2220 return cfq_var_show(__data, (page)); \
2221}
2222SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2223SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
2224SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2225SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2226SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0);
2227SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0);
2228SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2229SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2230SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2231SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2232SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
2233#undef SHOW_FUNCTION
2234
2235#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2236static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
2237{ \
2238 unsigned int __data; \
2239 int ret = cfq_var_store(&__data, (page), count); \
2240 if (__data < (MIN)) \
2241 __data = (MIN); \
2242 else if (__data > (MAX)) \
2243 __data = (MAX); \
2244 if (__CONV) \
2245 *(__PTR) = msecs_to_jiffies(__data); \
2246 else \
2247 *(__PTR) = __data; \
2248 return ret; \
2249}
2250STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2251STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
2252STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1);
2253STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1);
2254STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2255STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0);
2256STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2257STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2258STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2259STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0);
2260STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
2261#undef STORE_FUNCTION
2262
2263static struct cfq_fs_entry cfq_quantum_entry = {
2264 .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
2265 .show = cfq_quantum_show,
2266 .store = cfq_quantum_store,
2267};
2268static struct cfq_fs_entry cfq_queued_entry = {
2269 .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
2270 .show = cfq_queued_show,
2271 .store = cfq_queued_store,
2272};
2273static struct cfq_fs_entry cfq_fifo_expire_sync_entry = {
2274 .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
2275 .show = cfq_fifo_expire_sync_show,
2276 .store = cfq_fifo_expire_sync_store,
2277};
2278static struct cfq_fs_entry cfq_fifo_expire_async_entry = {
2279 .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
2280 .show = cfq_fifo_expire_async_show,
2281 .store = cfq_fifo_expire_async_store,
2282};
2283static struct cfq_fs_entry cfq_back_max_entry = {
2284 .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
2285 .show = cfq_back_max_show,
2286 .store = cfq_back_max_store,
2287};
2288static struct cfq_fs_entry cfq_back_penalty_entry = {
2289 .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
2290 .show = cfq_back_penalty_show,
2291 .store = cfq_back_penalty_store,
2292};
2293static struct cfq_fs_entry cfq_slice_sync_entry = {
2294 .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR },
2295 .show = cfq_slice_sync_show,
2296 .store = cfq_slice_sync_store,
2297};
2298static struct cfq_fs_entry cfq_slice_async_entry = {
2299 .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR },
2300 .show = cfq_slice_async_show,
2301 .store = cfq_slice_async_store,
2302};
2303static struct cfq_fs_entry cfq_slice_async_rq_entry = {
2304 .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR },
2305 .show = cfq_slice_async_rq_show,
2306 .store = cfq_slice_async_rq_store,
2307};
2308static struct cfq_fs_entry cfq_slice_idle_entry = {
2309 .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR },
2310 .show = cfq_slice_idle_show,
2311 .store = cfq_slice_idle_store,
2312};
2313static struct cfq_fs_entry cfq_max_depth_entry = {
2314 .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR },
2315 .show = cfq_max_depth_show,
2316 .store = cfq_max_depth_store,
2317};
2318
2319static struct attribute *default_attrs[] = {
2320 &cfq_quantum_entry.attr,
2321 &cfq_queued_entry.attr,
2322 &cfq_fifo_expire_sync_entry.attr,
2323 &cfq_fifo_expire_async_entry.attr,
2324 &cfq_back_max_entry.attr,
2325 &cfq_back_penalty_entry.attr,
2326 &cfq_slice_sync_entry.attr,
2327 &cfq_slice_async_entry.attr,
2328 &cfq_slice_async_rq_entry.attr,
2329 &cfq_slice_idle_entry.attr,
2330 &cfq_max_depth_entry.attr,
2331 NULL,
2332};
2333
2334#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
2335
2336static ssize_t
2337cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
2338{
2339 elevator_t *e = container_of(kobj, elevator_t, kobj);
2340 struct cfq_fs_entry *entry = to_cfq(attr);
2341
2342 if (!entry->show)
2343 return -EIO;
2344
2345 return entry->show(e->elevator_data, page);
2346}
2347
2348static ssize_t
2349cfq_attr_store(struct kobject *kobj, struct attribute *attr,
2350 const char *page, size_t length)
2351{
2352 elevator_t *e = container_of(kobj, elevator_t, kobj);
2353 struct cfq_fs_entry *entry = to_cfq(attr);
2354
2355 if (!entry->store)
2356 return -EIO;
2357
2358 return entry->store(e->elevator_data, page, length);
2359}
2360
2361static struct sysfs_ops cfq_sysfs_ops = {
2362 .show = cfq_attr_show,
2363 .store = cfq_attr_store,
2364};
2365
2366static struct kobj_type cfq_ktype = {
2367 .sysfs_ops = &cfq_sysfs_ops,
2368 .default_attrs = default_attrs,
2369};
2370
2371static struct elevator_type iosched_cfq = {
2372 .ops = {
2373 .elevator_merge_fn = cfq_merge,
2374 .elevator_merged_fn = cfq_merged_request,
2375 .elevator_merge_req_fn = cfq_merged_requests,
2376 .elevator_dispatch_fn = cfq_dispatch_requests,
2377 .elevator_add_req_fn = cfq_insert_request,
2378 .elevator_activate_req_fn = cfq_activate_request,
2379 .elevator_deactivate_req_fn = cfq_deactivate_request,
2380 .elevator_queue_empty_fn = cfq_queue_empty,
2381 .elevator_completed_req_fn = cfq_completed_request,
2382 .elevator_former_req_fn = cfq_former_request,
2383 .elevator_latter_req_fn = cfq_latter_request,
2384 .elevator_set_req_fn = cfq_set_request,
2385 .elevator_put_req_fn = cfq_put_request,
2386 .elevator_may_queue_fn = cfq_may_queue,
2387 .elevator_init_fn = cfq_init_queue,
2388 .elevator_exit_fn = cfq_exit_queue,
2389 },
2390 .elevator_ktype = &cfq_ktype,
2391 .elevator_name = "cfq",
2392 .elevator_owner = THIS_MODULE,
2393};
2394
2395static int __init cfq_init(void)
2396{
2397 int ret;
2398
2399 /*
2400 * could be 0 on HZ < 1000 setups
2401 */
2402 if (!cfq_slice_async)
2403 cfq_slice_async = 1;
2404 if (!cfq_slice_idle)
2405 cfq_slice_idle = 1;
2406
2407 if (cfq_slab_setup())
2408 return -ENOMEM;
2409
2410 ret = elv_register(&iosched_cfq);
2411 if (ret)
2412 cfq_slab_kill();
2413
2414 return ret;
2415}
2416
2417static void __exit cfq_exit(void)
2418{
2419 elv_unregister(&iosched_cfq);
2420 cfq_slab_kill();
2421}
2422
2423module_init(cfq_init);
2424module_exit(cfq_exit);
2425
2426MODULE_AUTHOR("Jens Axboe");
2427MODULE_LICENSE("GPL");
2428MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-01 21:43:21 -0500