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Commit | Line | Data |
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1 | /* | |
2 | * CFQ, or complete fairness queueing, disk scheduler. | |
3 | * | |
4 | * Based on ideas from a previously unfinished io | |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
6 | * | |
7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
8 | */ | |
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> | |
15 | ||
16 | /* | |
17 | * tunables | |
18 | */ | |
19 | static const int cfq_quantum = 4; /* max queue in one round of service */ | |
20 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; | |
21 | static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ | |
22 | static const int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
23 | ||
24 | static const int cfq_slice_sync = HZ / 10; | |
25 | static int cfq_slice_async = HZ / 25; | |
26 | static const int cfq_slice_async_rq = 2; | |
27 | static int cfq_slice_idle = HZ / 125; | |
28 | ||
29 | #define CFQ_IDLE_GRACE (HZ / 10) | |
30 | #define CFQ_SLICE_SCALE (5) | |
31 | ||
32 | #define CFQ_KEY_ASYNC (0) | |
33 | ||
34 | /* | |
35 | * for the hash of cfqq inside the cfqd | |
36 | */ | |
37 | #define CFQ_QHASH_SHIFT 6 | |
38 | #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) | |
39 | #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) | |
40 | ||
41 | #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) | |
42 | ||
43 | #define RQ_CIC(rq) ((struct cfq_io_context*)(rq)->elevator_private) | |
44 | #define RQ_CFQQ(rq) ((rq)->elevator_private2) | |
45 | ||
46 | static struct kmem_cache *cfq_pool; | |
47 | static struct kmem_cache *cfq_ioc_pool; | |
48 | ||
49 | static DEFINE_PER_CPU(unsigned long, ioc_count); | |
50 | static struct completion *ioc_gone; | |
51 | ||
52 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR | |
53 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
54 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
55 | ||
56 | #define ASYNC (0) | |
57 | #define SYNC (1) | |
58 | ||
59 | #define cfq_cfqq_dispatched(cfqq) \ | |
60 | ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) | |
61 | ||
62 | #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) | |
63 | ||
64 | #define cfq_cfqq_sync(cfqq) \ | |
65 | (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) | |
66 | ||
67 | #define sample_valid(samples) ((samples) > 80) | |
68 | ||
69 | /* | |
70 | * Per block device queue structure | |
71 | */ | |
72 | struct cfq_data { | |
73 | request_queue_t *queue; | |
74 | ||
75 | /* | |
76 | * rr list of queues with requests and the count of them | |
77 | */ | |
78 | struct list_head rr_list[CFQ_PRIO_LISTS]; | |
79 | struct list_head busy_rr; | |
80 | struct list_head cur_rr; | |
81 | struct list_head idle_rr; | |
82 | unsigned int busy_queues; | |
83 | ||
84 | /* | |
85 | * cfqq lookup hash | |
86 | */ | |
87 | struct hlist_head *cfq_hash; | |
88 | ||
89 | int rq_in_driver; | |
90 | int hw_tag; | |
91 | ||
92 | /* | |
93 | * idle window management | |
94 | */ | |
95 | struct timer_list idle_slice_timer; | |
96 | struct work_struct unplug_work; | |
97 | ||
98 | struct cfq_queue *active_queue; | |
99 | struct cfq_io_context *active_cic; | |
100 | int cur_prio, cur_end_prio; | |
101 | unsigned int dispatch_slice; | |
102 | ||
103 | struct timer_list idle_class_timer; | |
104 | ||
105 | sector_t last_sector; | |
106 | unsigned long last_end_request; | |
107 | ||
108 | /* | |
109 | * tunables, see top of file | |
110 | */ | |
111 | unsigned int cfq_quantum; | |
112 | unsigned int cfq_fifo_expire[2]; | |
113 | unsigned int cfq_back_penalty; | |
114 | unsigned int cfq_back_max; | |
115 | unsigned int cfq_slice[2]; | |
116 | unsigned int cfq_slice_async_rq; | |
117 | unsigned int cfq_slice_idle; | |
118 | ||
119 | struct list_head cic_list; | |
120 | }; | |
121 | ||
122 | /* | |
123 | * Per process-grouping structure | |
124 | */ | |
125 | struct cfq_queue { | |
126 | /* reference count */ | |
127 | atomic_t ref; | |
128 | /* parent cfq_data */ | |
129 | struct cfq_data *cfqd; | |
130 | /* cfqq lookup hash */ | |
131 | struct hlist_node cfq_hash; | |
132 | /* hash key */ | |
133 | unsigned int key; | |
134 | /* member of the rr/busy/cur/idle cfqd list */ | |
135 | struct list_head cfq_list; | |
136 | /* sorted list of pending requests */ | |
137 | struct rb_root sort_list; | |
138 | /* if fifo isn't expired, next request to serve */ | |
139 | struct request *next_rq; | |
140 | /* requests queued in sort_list */ | |
141 | int queued[2]; | |
142 | /* currently allocated requests */ | |
143 | int allocated[2]; | |
144 | /* pending metadata requests */ | |
145 | int meta_pending; | |
146 | /* fifo list of requests in sort_list */ | |
147 | struct list_head fifo; | |
148 | ||
149 | unsigned long slice_start; | |
150 | unsigned long slice_end; | |
151 | unsigned long slice_left; | |
152 | ||
153 | /* number of requests that are on the dispatch list */ | |
154 | int on_dispatch[2]; | |
155 | ||
156 | /* io prio of this group */ | |
157 | unsigned short ioprio, org_ioprio; | |
158 | unsigned short ioprio_class, org_ioprio_class; | |
159 | ||
160 | /* various state flags, see below */ | |
161 | unsigned int flags; | |
162 | }; | |
163 | ||
164 | enum cfqq_state_flags { | |
165 | CFQ_CFQQ_FLAG_on_rr = 0, | |
166 | CFQ_CFQQ_FLAG_wait_request, | |
167 | CFQ_CFQQ_FLAG_must_alloc, | |
168 | CFQ_CFQQ_FLAG_must_alloc_slice, | |
169 | CFQ_CFQQ_FLAG_must_dispatch, | |
170 | CFQ_CFQQ_FLAG_fifo_expire, | |
171 | CFQ_CFQQ_FLAG_idle_window, | |
172 | CFQ_CFQQ_FLAG_prio_changed, | |
173 | CFQ_CFQQ_FLAG_queue_new, | |
174 | }; | |
175 | ||
176 | #define CFQ_CFQQ_FNS(name) \ | |
177 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
178 | { \ | |
179 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
180 | } \ | |
181 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
182 | { \ | |
183 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
184 | } \ | |
185 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
186 | { \ | |
187 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
188 | } | |
189 | ||
190 | CFQ_CFQQ_FNS(on_rr); | |
191 | CFQ_CFQQ_FNS(wait_request); | |
192 | CFQ_CFQQ_FNS(must_alloc); | |
193 | CFQ_CFQQ_FNS(must_alloc_slice); | |
194 | CFQ_CFQQ_FNS(must_dispatch); | |
195 | CFQ_CFQQ_FNS(fifo_expire); | |
196 | CFQ_CFQQ_FNS(idle_window); | |
197 | CFQ_CFQQ_FNS(prio_changed); | |
198 | CFQ_CFQQ_FNS(queue_new); | |
199 | #undef CFQ_CFQQ_FNS | |
200 | ||
201 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); | |
202 | static void cfq_dispatch_insert(request_queue_t *, struct request *); | |
203 | static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); | |
204 | ||
205 | /* | |
206 | * scheduler run of queue, if there are requests pending and no one in the | |
207 | * driver that will restart queueing | |
208 | */ | |
209 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
210 | { | |
211 | if (cfqd->busy_queues) | |
212 | kblockd_schedule_work(&cfqd->unplug_work); | |
213 | } | |
214 | ||
215 | static int cfq_queue_empty(request_queue_t *q) | |
216 | { | |
217 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
218 | ||
219 | return !cfqd->busy_queues; | |
220 | } | |
221 | ||
222 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw, int is_sync) | |
223 | { | |
224 | /* | |
225 | * Use the per-process queue, for read requests and syncronous writes | |
226 | */ | |
227 | if (!(rw & REQ_RW) || is_sync) | |
228 | return task->pid; | |
229 | ||
230 | return CFQ_KEY_ASYNC; | |
231 | } | |
232 | ||
233 | /* | |
234 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. | |
235 | * We choose the request that is closest to the head right now. Distance | |
236 | * behind the head is penalized and only allowed to a certain extent. | |
237 | */ | |
238 | static struct request * | |
239 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
240 | { | |
241 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
242 | unsigned long back_max; | |
243 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ | |
244 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
245 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
246 | ||
247 | if (rq1 == NULL || rq1 == rq2) | |
248 | return rq2; | |
249 | if (rq2 == NULL) | |
250 | return rq1; | |
251 | ||
252 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) | |
253 | return rq1; | |
254 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
255 | return rq2; | |
256 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) | |
257 | return rq1; | |
258 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
259 | return rq2; | |
260 | ||
261 | s1 = rq1->sector; | |
262 | s2 = rq2->sector; | |
263 | ||
264 | last = cfqd->last_sector; | |
265 | ||
266 | /* | |
267 | * by definition, 1KiB is 2 sectors | |
268 | */ | |
269 | back_max = cfqd->cfq_back_max * 2; | |
270 | ||
271 | /* | |
272 | * Strict one way elevator _except_ in the case where we allow | |
273 | * short backward seeks which are biased as twice the cost of a | |
274 | * similar forward seek. | |
275 | */ | |
276 | if (s1 >= last) | |
277 | d1 = s1 - last; | |
278 | else if (s1 + back_max >= last) | |
279 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
280 | else | |
281 | wrap |= CFQ_RQ1_WRAP; | |
282 | ||
283 | if (s2 >= last) | |
284 | d2 = s2 - last; | |
285 | else if (s2 + back_max >= last) | |
286 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
287 | else | |
288 | wrap |= CFQ_RQ2_WRAP; | |
289 | ||
290 | /* Found required data */ | |
291 | ||
292 | /* | |
293 | * By doing switch() on the bit mask "wrap" we avoid having to | |
294 | * check two variables for all permutations: --> faster! | |
295 | */ | |
296 | switch (wrap) { | |
297 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ | |
298 | if (d1 < d2) | |
299 | return rq1; | |
300 | else if (d2 < d1) | |
301 | return rq2; | |
302 | else { | |
303 | if (s1 >= s2) | |
304 | return rq1; | |
305 | else | |
306 | return rq2; | |
307 | } | |
308 | ||
309 | case CFQ_RQ2_WRAP: | |
310 | return rq1; | |
311 | case CFQ_RQ1_WRAP: | |
312 | return rq2; | |
313 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
314 | default: | |
315 | /* | |
316 | * Since both rqs are wrapped, | |
317 | * start with the one that's further behind head | |
318 | * (--> only *one* back seek required), | |
319 | * since back seek takes more time than forward. | |
320 | */ | |
321 | if (s1 <= s2) | |
322 | return rq1; | |
323 | else | |
324 | return rq2; | |
325 | } | |
326 | } | |
327 | ||
328 | /* | |
329 | * would be nice to take fifo expire time into account as well | |
330 | */ | |
331 | static struct request * | |
332 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
333 | struct request *last) | |
334 | { | |
335 | struct rb_node *rbnext = rb_next(&last->rb_node); | |
336 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
337 | struct request *next = NULL, *prev = NULL; | |
338 | ||
339 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); | |
340 | ||
341 | if (rbprev) | |
342 | prev = rb_entry_rq(rbprev); | |
343 | ||
344 | if (rbnext) | |
345 | next = rb_entry_rq(rbnext); | |
346 | else { | |
347 | rbnext = rb_first(&cfqq->sort_list); | |
348 | if (rbnext && rbnext != &last->rb_node) | |
349 | next = rb_entry_rq(rbnext); | |
350 | } | |
351 | ||
352 | return cfq_choose_req(cfqd, next, prev); | |
353 | } | |
354 | ||
355 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) | |
356 | { | |
357 | struct cfq_data *cfqd = cfqq->cfqd; | |
358 | struct list_head *list; | |
359 | ||
360 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
361 | ||
362 | list_del(&cfqq->cfq_list); | |
363 | ||
364 | if (cfq_class_rt(cfqq)) | |
365 | list = &cfqd->cur_rr; | |
366 | else if (cfq_class_idle(cfqq)) | |
367 | list = &cfqd->idle_rr; | |
368 | else { | |
369 | /* | |
370 | * if cfqq has requests in flight, don't allow it to be | |
371 | * found in cfq_set_active_queue before it has finished them. | |
372 | * this is done to increase fairness between a process that | |
373 | * has lots of io pending vs one that only generates one | |
374 | * sporadically or synchronously | |
375 | */ | |
376 | if (cfq_cfqq_dispatched(cfqq)) | |
377 | list = &cfqd->busy_rr; | |
378 | else | |
379 | list = &cfqd->rr_list[cfqq->ioprio]; | |
380 | } | |
381 | ||
382 | /* | |
383 | * If this queue was preempted or is new (never been serviced), let | |
384 | * it be added first for fairness but beind other new queues. | |
385 | * Otherwise, just add to the back of the list. | |
386 | */ | |
387 | if (preempted || cfq_cfqq_queue_new(cfqq)) { | |
388 | struct list_head *n = list; | |
389 | struct cfq_queue *__cfqq; | |
390 | ||
391 | while (n->next != list) { | |
392 | __cfqq = list_entry_cfqq(n->next); | |
393 | if (!cfq_cfqq_queue_new(__cfqq)) | |
394 | break; | |
395 | ||
396 | n = n->next; | |
397 | } | |
398 | ||
399 | list = n; | |
400 | } | |
401 | ||
402 | list_add_tail(&cfqq->cfq_list, list); | |
403 | } | |
404 | ||
405 | /* | |
406 | * add to busy list of queues for service, trying to be fair in ordering | |
407 | * the pending list according to last request service | |
408 | */ | |
409 | static inline void | |
410 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
411 | { | |
412 | BUG_ON(cfq_cfqq_on_rr(cfqq)); | |
413 | cfq_mark_cfqq_on_rr(cfqq); | |
414 | cfqd->busy_queues++; | |
415 | ||
416 | cfq_resort_rr_list(cfqq, 0); | |
417 | } | |
418 | ||
419 | static inline void | |
420 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
421 | { | |
422 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
423 | cfq_clear_cfqq_on_rr(cfqq); | |
424 | list_del_init(&cfqq->cfq_list); | |
425 | ||
426 | BUG_ON(!cfqd->busy_queues); | |
427 | cfqd->busy_queues--; | |
428 | } | |
429 | ||
430 | /* | |
431 | * rb tree support functions | |
432 | */ | |
433 | static inline void cfq_del_rq_rb(struct request *rq) | |
434 | { | |
435 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
436 | struct cfq_data *cfqd = cfqq->cfqd; | |
437 | const int sync = rq_is_sync(rq); | |
438 | ||
439 | BUG_ON(!cfqq->queued[sync]); | |
440 | cfqq->queued[sync]--; | |
441 | ||
442 | elv_rb_del(&cfqq->sort_list, rq); | |
443 | ||
444 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) | |
445 | cfq_del_cfqq_rr(cfqd, cfqq); | |
446 | } | |
447 | ||
448 | static void cfq_add_rq_rb(struct request *rq) | |
449 | { | |
450 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
451 | struct cfq_data *cfqd = cfqq->cfqd; | |
452 | struct request *__alias; | |
453 | ||
454 | cfqq->queued[rq_is_sync(rq)]++; | |
455 | ||
456 | /* | |
457 | * looks a little odd, but the first insert might return an alias. | |
458 | * if that happens, put the alias on the dispatch list | |
459 | */ | |
460 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) | |
461 | cfq_dispatch_insert(cfqd->queue, __alias); | |
462 | ||
463 | if (!cfq_cfqq_on_rr(cfqq)) | |
464 | cfq_add_cfqq_rr(cfqd, cfqq); | |
465 | } | |
466 | ||
467 | static inline void | |
468 | cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) | |
469 | { | |
470 | elv_rb_del(&cfqq->sort_list, rq); | |
471 | cfqq->queued[rq_is_sync(rq)]--; | |
472 | cfq_add_rq_rb(rq); | |
473 | } | |
474 | ||
475 | static struct request * | |
476 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
477 | { | |
478 | struct task_struct *tsk = current; | |
479 | pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio), bio_sync(bio)); | |
480 | struct cfq_queue *cfqq; | |
481 | ||
482 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); | |
483 | if (cfqq) { | |
484 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
485 | ||
486 | return elv_rb_find(&cfqq->sort_list, sector); | |
487 | } | |
488 | ||
489 | return NULL; | |
490 | } | |
491 | ||
492 | static void cfq_activate_request(request_queue_t *q, struct request *rq) | |
493 | { | |
494 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
495 | ||
496 | cfqd->rq_in_driver++; | |
497 | ||
498 | /* | |
499 | * If the depth is larger 1, it really could be queueing. But lets | |
500 | * make the mark a little higher - idling could still be good for | |
501 | * low queueing, and a low queueing number could also just indicate | |
502 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
503 | */ | |
504 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
505 | cfqd->hw_tag = 1; | |
506 | } | |
507 | ||
508 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) | |
509 | { | |
510 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
511 | ||
512 | WARN_ON(!cfqd->rq_in_driver); | |
513 | cfqd->rq_in_driver--; | |
514 | } | |
515 | ||
516 | static void cfq_remove_request(struct request *rq) | |
517 | { | |
518 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
519 | ||
520 | if (cfqq->next_rq == rq) | |
521 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
522 | ||
523 | list_del_init(&rq->queuelist); | |
524 | cfq_del_rq_rb(rq); | |
525 | ||
526 | if (rq_is_meta(rq)) { | |
527 | WARN_ON(!cfqq->meta_pending); | |
528 | cfqq->meta_pending--; | |
529 | } | |
530 | } | |
531 | ||
532 | static int | |
533 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
534 | { | |
535 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
536 | struct request *__rq; | |
537 | ||
538 | __rq = cfq_find_rq_fmerge(cfqd, bio); | |
539 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
540 | *req = __rq; | |
541 | return ELEVATOR_FRONT_MERGE; | |
542 | } | |
543 | ||
544 | return ELEVATOR_NO_MERGE; | |
545 | } | |
546 | ||
547 | static void cfq_merged_request(request_queue_t *q, struct request *req, | |
548 | int type) | |
549 | { | |
550 | if (type == ELEVATOR_FRONT_MERGE) { | |
551 | struct cfq_queue *cfqq = RQ_CFQQ(req); | |
552 | ||
553 | cfq_reposition_rq_rb(cfqq, req); | |
554 | } | |
555 | } | |
556 | ||
557 | static void | |
558 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
559 | struct request *next) | |
560 | { | |
561 | /* | |
562 | * reposition in fifo if next is older than rq | |
563 | */ | |
564 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
565 | time_before(next->start_time, rq->start_time)) | |
566 | list_move(&rq->queuelist, &next->queuelist); | |
567 | ||
568 | cfq_remove_request(next); | |
569 | } | |
570 | ||
571 | static int cfq_allow_merge(request_queue_t *q, struct request *rq, | |
572 | struct bio *bio) | |
573 | { | |
574 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
575 | const int rw = bio_data_dir(bio); | |
576 | struct cfq_queue *cfqq; | |
577 | pid_t key; | |
578 | ||
579 | /* | |
580 | * If bio is async or a write, always allow merge | |
581 | */ | |
582 | if (!bio_sync(bio) || rw == WRITE) | |
583 | return 1; | |
584 | ||
585 | /* | |
586 | * bio is sync. if request is not, disallow. | |
587 | */ | |
588 | if (!rq_is_sync(rq)) | |
589 | return 0; | |
590 | ||
591 | /* | |
592 | * Ok, both bio and request are sync. Allow merge if they are | |
593 | * from the same queue. | |
594 | */ | |
595 | key = cfq_queue_pid(current, rw, 1); | |
596 | cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio); | |
597 | if (cfqq != RQ_CFQQ(rq)) | |
598 | return 0; | |
599 | ||
600 | return 1; | |
601 | } | |
602 | ||
603 | static inline void | |
604 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
605 | { | |
606 | if (cfqq) { | |
607 | /* | |
608 | * stop potential idle class queues waiting service | |
609 | */ | |
610 | del_timer(&cfqd->idle_class_timer); | |
611 | ||
612 | cfqq->slice_start = jiffies; | |
613 | cfqq->slice_end = 0; | |
614 | cfqq->slice_left = 0; | |
615 | cfq_clear_cfqq_must_alloc_slice(cfqq); | |
616 | cfq_clear_cfqq_fifo_expire(cfqq); | |
617 | } | |
618 | ||
619 | cfqd->active_queue = cfqq; | |
620 | } | |
621 | ||
622 | /* | |
623 | * current cfqq expired its slice (or was too idle), select new one | |
624 | */ | |
625 | static void | |
626 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
627 | int preempted) | |
628 | { | |
629 | unsigned long now = jiffies; | |
630 | ||
631 | if (cfq_cfqq_wait_request(cfqq)) | |
632 | del_timer(&cfqd->idle_slice_timer); | |
633 | ||
634 | if (!preempted && !cfq_cfqq_dispatched(cfqq)) | |
635 | cfq_schedule_dispatch(cfqd); | |
636 | ||
637 | cfq_clear_cfqq_must_dispatch(cfqq); | |
638 | cfq_clear_cfqq_wait_request(cfqq); | |
639 | cfq_clear_cfqq_queue_new(cfqq); | |
640 | ||
641 | /* | |
642 | * store what was left of this slice, if the queue idled out | |
643 | * or was preempted | |
644 | */ | |
645 | if (time_after(cfqq->slice_end, now)) | |
646 | cfqq->slice_left = cfqq->slice_end - now; | |
647 | else | |
648 | cfqq->slice_left = 0; | |
649 | ||
650 | if (cfq_cfqq_on_rr(cfqq)) | |
651 | cfq_resort_rr_list(cfqq, preempted); | |
652 | ||
653 | if (cfqq == cfqd->active_queue) | |
654 | cfqd->active_queue = NULL; | |
655 | ||
656 | if (cfqd->active_cic) { | |
657 | put_io_context(cfqd->active_cic->ioc); | |
658 | cfqd->active_cic = NULL; | |
659 | } | |
660 | ||
661 | cfqd->dispatch_slice = 0; | |
662 | } | |
663 | ||
664 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
665 | { | |
666 | struct cfq_queue *cfqq = cfqd->active_queue; | |
667 | ||
668 | if (cfqq) | |
669 | __cfq_slice_expired(cfqd, cfqq, preempted); | |
670 | } | |
671 | ||
672 | /* | |
673 | * 0 | |
674 | * 0,1 | |
675 | * 0,1,2 | |
676 | * 0,1,2,3 | |
677 | * 0,1,2,3,4 | |
678 | * 0,1,2,3,4,5 | |
679 | * 0,1,2,3,4,5,6 | |
680 | * 0,1,2,3,4,5,6,7 | |
681 | */ | |
682 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
683 | { | |
684 | int prio, wrap; | |
685 | ||
686 | prio = -1; | |
687 | wrap = 0; | |
688 | do { | |
689 | int p; | |
690 | ||
691 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
692 | if (!list_empty(&cfqd->rr_list[p])) { | |
693 | prio = p; | |
694 | break; | |
695 | } | |
696 | } | |
697 | ||
698 | if (prio != -1) | |
699 | break; | |
700 | cfqd->cur_prio = 0; | |
701 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
702 | cfqd->cur_end_prio = 0; | |
703 | if (wrap) | |
704 | break; | |
705 | wrap = 1; | |
706 | } | |
707 | } while (1); | |
708 | ||
709 | if (unlikely(prio == -1)) | |
710 | return -1; | |
711 | ||
712 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
713 | ||
714 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
715 | ||
716 | cfqd->cur_prio = prio + 1; | |
717 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
718 | cfqd->cur_end_prio = cfqd->cur_prio; | |
719 | cfqd->cur_prio = 0; | |
720 | } | |
721 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
722 | cfqd->cur_prio = 0; | |
723 | cfqd->cur_end_prio = 0; | |
724 | } | |
725 | ||
726 | return prio; | |
727 | } | |
728 | ||
729 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) | |
730 | { | |
731 | struct cfq_queue *cfqq = NULL; | |
732 | ||
733 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) { | |
734 | /* | |
735 | * if current list is non-empty, grab first entry. if it is | |
736 | * empty, get next prio level and grab first entry then if any | |
737 | * are spliced | |
738 | */ | |
739 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
740 | } else if (!list_empty(&cfqd->busy_rr)) { | |
741 | /* | |
742 | * If no new queues are available, check if the busy list has | |
743 | * some before falling back to idle io. | |
744 | */ | |
745 | cfqq = list_entry_cfqq(cfqd->busy_rr.next); | |
746 | } else if (!list_empty(&cfqd->idle_rr)) { | |
747 | /* | |
748 | * if we have idle queues and no rt or be queues had pending | |
749 | * requests, either allow immediate service if the grace period | |
750 | * has passed or arm the idle grace timer | |
751 | */ | |
752 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
753 | ||
754 | if (time_after_eq(jiffies, end)) | |
755 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
756 | else | |
757 | mod_timer(&cfqd->idle_class_timer, end); | |
758 | } | |
759 | ||
760 | __cfq_set_active_queue(cfqd, cfqq); | |
761 | return cfqq; | |
762 | } | |
763 | ||
764 | #define CIC_SEEKY(cic) ((cic)->seek_mean > (128 * 1024)) | |
765 | ||
766 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
767 | ||
768 | { | |
769 | struct cfq_io_context *cic; | |
770 | unsigned long sl; | |
771 | ||
772 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); | |
773 | WARN_ON(cfqq != cfqd->active_queue); | |
774 | ||
775 | /* | |
776 | * idle is disabled, either manually or by past process history | |
777 | */ | |
778 | if (!cfqd->cfq_slice_idle) | |
779 | return 0; | |
780 | if (!cfq_cfqq_idle_window(cfqq)) | |
781 | return 0; | |
782 | /* | |
783 | * task has exited, don't wait | |
784 | */ | |
785 | cic = cfqd->active_cic; | |
786 | if (!cic || !cic->ioc->task) | |
787 | return 0; | |
788 | ||
789 | cfq_mark_cfqq_must_dispatch(cfqq); | |
790 | cfq_mark_cfqq_wait_request(cfqq); | |
791 | ||
792 | sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); | |
793 | ||
794 | /* | |
795 | * we don't want to idle for seeks, but we do want to allow | |
796 | * fair distribution of slice time for a process doing back-to-back | |
797 | * seeks. so allow a little bit of time for him to submit a new rq | |
798 | */ | |
799 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) | |
800 | sl = min(sl, msecs_to_jiffies(2)); | |
801 | ||
802 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); | |
803 | return 1; | |
804 | } | |
805 | ||
806 | static void cfq_dispatch_insert(request_queue_t *q, struct request *rq) | |
807 | { | |
808 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
809 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
810 | ||
811 | cfq_remove_request(rq); | |
812 | cfqq->on_dispatch[rq_is_sync(rq)]++; | |
813 | elv_dispatch_sort(q, rq); | |
814 | ||
815 | rq = list_entry(q->queue_head.prev, struct request, queuelist); | |
816 | cfqd->last_sector = rq->sector + rq->nr_sectors; | |
817 | } | |
818 | ||
819 | /* | |
820 | * return expired entry, or NULL to just start from scratch in rbtree | |
821 | */ | |
822 | static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq) | |
823 | { | |
824 | struct cfq_data *cfqd = cfqq->cfqd; | |
825 | struct request *rq; | |
826 | int fifo; | |
827 | ||
828 | if (cfq_cfqq_fifo_expire(cfqq)) | |
829 | return NULL; | |
830 | if (list_empty(&cfqq->fifo)) | |
831 | return NULL; | |
832 | ||
833 | fifo = cfq_cfqq_class_sync(cfqq); | |
834 | rq = rq_entry_fifo(cfqq->fifo.next); | |
835 | ||
836 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
837 | cfq_mark_cfqq_fifo_expire(cfqq); | |
838 | return rq; | |
839 | } | |
840 | ||
841 | return NULL; | |
842 | } | |
843 | ||
844 | /* | |
845 | * Scale schedule slice based on io priority. Use the sync time slice only | |
846 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
847 | * io only, should not get full sync slice length. | |
848 | */ | |
849 | static inline int | |
850 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
851 | { | |
852 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
853 | ||
854 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
855 | ||
856 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
857 | } | |
858 | ||
859 | static inline void | |
860 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
861 | { | |
862 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
863 | } | |
864 | ||
865 | static inline int | |
866 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
867 | { | |
868 | const int base_rq = cfqd->cfq_slice_async_rq; | |
869 | ||
870 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
871 | ||
872 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); | |
873 | } | |
874 | ||
875 | /* | |
876 | * get next queue for service | |
877 | */ | |
878 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) | |
879 | { | |
880 | unsigned long now = jiffies; | |
881 | struct cfq_queue *cfqq; | |
882 | ||
883 | cfqq = cfqd->active_queue; | |
884 | if (!cfqq) | |
885 | goto new_queue; | |
886 | ||
887 | /* | |
888 | * slice has expired | |
889 | */ | |
890 | if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) | |
891 | goto expire; | |
892 | ||
893 | /* | |
894 | * if queue has requests, dispatch one. if not, check if | |
895 | * enough slice is left to wait for one | |
896 | */ | |
897 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) | |
898 | goto keep_queue; | |
899 | else if (cfq_cfqq_dispatched(cfqq)) { | |
900 | cfqq = NULL; | |
901 | goto keep_queue; | |
902 | } else if (cfq_cfqq_class_sync(cfqq)) { | |
903 | if (cfq_arm_slice_timer(cfqd, cfqq)) | |
904 | return NULL; | |
905 | } | |
906 | ||
907 | expire: | |
908 | cfq_slice_expired(cfqd, 0); | |
909 | new_queue: | |
910 | cfqq = cfq_set_active_queue(cfqd); | |
911 | keep_queue: | |
912 | return cfqq; | |
913 | } | |
914 | ||
915 | static int | |
916 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
917 | int max_dispatch) | |
918 | { | |
919 | int dispatched = 0; | |
920 | ||
921 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
922 | ||
923 | do { | |
924 | struct request *rq; | |
925 | ||
926 | /* | |
927 | * follow expired path, else get first next available | |
928 | */ | |
929 | if ((rq = cfq_check_fifo(cfqq)) == NULL) | |
930 | rq = cfqq->next_rq; | |
931 | ||
932 | /* | |
933 | * finally, insert request into driver dispatch list | |
934 | */ | |
935 | cfq_dispatch_insert(cfqd->queue, rq); | |
936 | ||
937 | cfqd->dispatch_slice++; | |
938 | dispatched++; | |
939 | ||
940 | if (!cfqd->active_cic) { | |
941 | atomic_inc(&RQ_CIC(rq)->ioc->refcount); | |
942 | cfqd->active_cic = RQ_CIC(rq); | |
943 | } | |
944 | ||
945 | if (RB_EMPTY_ROOT(&cfqq->sort_list)) | |
946 | break; | |
947 | ||
948 | } while (dispatched < max_dispatch); | |
949 | ||
950 | /* | |
951 | * if slice end isn't set yet, set it. | |
952 | */ | |
953 | if (!cfqq->slice_end) | |
954 | cfq_set_prio_slice(cfqd, cfqq); | |
955 | ||
956 | /* | |
957 | * expire an async queue immediately if it has used up its slice. idle | |
958 | * queue always expire after 1 dispatch round. | |
959 | */ | |
960 | if ((!cfq_cfqq_sync(cfqq) && | |
961 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
962 | cfq_class_idle(cfqq) || | |
963 | !cfq_cfqq_idle_window(cfqq)) | |
964 | cfq_slice_expired(cfqd, 0); | |
965 | ||
966 | return dispatched; | |
967 | } | |
968 | ||
969 | static int | |
970 | cfq_forced_dispatch_cfqqs(struct list_head *list) | |
971 | { | |
972 | struct cfq_queue *cfqq, *next; | |
973 | int dispatched; | |
974 | ||
975 | dispatched = 0; | |
976 | list_for_each_entry_safe(cfqq, next, list, cfq_list) { | |
977 | while (cfqq->next_rq) { | |
978 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
979 | dispatched++; | |
980 | } | |
981 | BUG_ON(!list_empty(&cfqq->fifo)); | |
982 | } | |
983 | ||
984 | return dispatched; | |
985 | } | |
986 | ||
987 | static int | |
988 | cfq_forced_dispatch(struct cfq_data *cfqd) | |
989 | { | |
990 | int i, dispatched = 0; | |
991 | ||
992 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
993 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]); | |
994 | ||
995 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr); | |
996 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); | |
997 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
998 | ||
999 | cfq_slice_expired(cfqd, 0); | |
1000 | ||
1001 | BUG_ON(cfqd->busy_queues); | |
1002 | ||
1003 | return dispatched; | |
1004 | } | |
1005 | ||
1006 | static int | |
1007 | cfq_dispatch_requests(request_queue_t *q, int force) | |
1008 | { | |
1009 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1010 | struct cfq_queue *cfqq, *prev_cfqq; | |
1011 | int dispatched; | |
1012 | ||
1013 | if (!cfqd->busy_queues) | |
1014 | return 0; | |
1015 | ||
1016 | if (unlikely(force)) | |
1017 | return cfq_forced_dispatch(cfqd); | |
1018 | ||
1019 | dispatched = 0; | |
1020 | prev_cfqq = NULL; | |
1021 | while ((cfqq = cfq_select_queue(cfqd)) != NULL) { | |
1022 | int max_dispatch; | |
1023 | ||
1024 | /* | |
1025 | * Don't repeat dispatch from the previous queue. | |
1026 | */ | |
1027 | if (prev_cfqq == cfqq) | |
1028 | break; | |
1029 | ||
1030 | cfq_clear_cfqq_must_dispatch(cfqq); | |
1031 | cfq_clear_cfqq_wait_request(cfqq); | |
1032 | del_timer(&cfqd->idle_slice_timer); | |
1033 | ||
1034 | max_dispatch = cfqd->cfq_quantum; | |
1035 | if (cfq_class_idle(cfqq)) | |
1036 | max_dispatch = 1; | |
1037 | ||
1038 | dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); | |
1039 | ||
1040 | /* | |
1041 | * If the dispatch cfqq has idling enabled and is still | |
1042 | * the active queue, break out. | |
1043 | */ | |
1044 | if (cfq_cfqq_idle_window(cfqq) && cfqd->active_queue) | |
1045 | break; | |
1046 | ||
1047 | prev_cfqq = cfqq; | |
1048 | } | |
1049 | ||
1050 | return dispatched; | |
1051 | } | |
1052 | ||
1053 | /* | |
1054 | * task holds one reference to the queue, dropped when task exits. each rq | |
1055 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1056 | * | |
1057 | * queue lock must be held here. | |
1058 | */ | |
1059 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1060 | { | |
1061 | struct cfq_data *cfqd = cfqq->cfqd; | |
1062 | ||
1063 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1064 | ||
1065 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1066 | return; | |
1067 | ||
1068 | BUG_ON(rb_first(&cfqq->sort_list)); | |
1069 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); | |
1070 | BUG_ON(cfq_cfqq_on_rr(cfqq)); | |
1071 | ||
1072 | if (unlikely(cfqd->active_queue == cfqq)) | |
1073 | __cfq_slice_expired(cfqd, cfqq, 0); | |
1074 | ||
1075 | /* | |
1076 | * it's on the empty list and still hashed | |
1077 | */ | |
1078 | list_del(&cfqq->cfq_list); | |
1079 | hlist_del(&cfqq->cfq_hash); | |
1080 | kmem_cache_free(cfq_pool, cfqq); | |
1081 | } | |
1082 | ||
1083 | static struct cfq_queue * | |
1084 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, | |
1085 | const int hashval) | |
1086 | { | |
1087 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
1088 | struct hlist_node *entry; | |
1089 | struct cfq_queue *__cfqq; | |
1090 | ||
1091 | hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) { | |
1092 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); | |
1093 | ||
1094 | if (__cfqq->key == key && (__p == prio || !prio)) | |
1095 | return __cfqq; | |
1096 | } | |
1097 | ||
1098 | return NULL; | |
1099 | } | |
1100 | ||
1101 | static struct cfq_queue * | |
1102 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) | |
1103 | { | |
1104 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); | |
1105 | } | |
1106 | ||
1107 | static void cfq_free_io_context(struct io_context *ioc) | |
1108 | { | |
1109 | struct cfq_io_context *__cic; | |
1110 | struct rb_node *n; | |
1111 | int freed = 0; | |
1112 | ||
1113 | while ((n = rb_first(&ioc->cic_root)) != NULL) { | |
1114 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1115 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
1116 | kmem_cache_free(cfq_ioc_pool, __cic); | |
1117 | freed++; | |
1118 | } | |
1119 | ||
1120 | elv_ioc_count_mod(ioc_count, -freed); | |
1121 | ||
1122 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) | |
1123 | complete(ioc_gone); | |
1124 | } | |
1125 | ||
1126 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1127 | { | |
1128 | if (unlikely(cfqq == cfqd->active_queue)) | |
1129 | __cfq_slice_expired(cfqd, cfqq, 0); | |
1130 | ||
1131 | cfq_put_queue(cfqq); | |
1132 | } | |
1133 | ||
1134 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, | |
1135 | struct cfq_io_context *cic) | |
1136 | { | |
1137 | list_del_init(&cic->queue_list); | |
1138 | smp_wmb(); | |
1139 | cic->key = NULL; | |
1140 | ||
1141 | if (cic->cfqq[ASYNC]) { | |
1142 | cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]); | |
1143 | cic->cfqq[ASYNC] = NULL; | |
1144 | } | |
1145 | ||
1146 | if (cic->cfqq[SYNC]) { | |
1147 | cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]); | |
1148 | cic->cfqq[SYNC] = NULL; | |
1149 | } | |
1150 | } | |
1151 | ||
1152 | ||
1153 | /* | |
1154 | * Called with interrupts disabled | |
1155 | */ | |
1156 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1157 | { | |
1158 | struct cfq_data *cfqd = cic->key; | |
1159 | ||
1160 | if (cfqd) { | |
1161 | request_queue_t *q = cfqd->queue; | |
1162 | ||
1163 | spin_lock_irq(q->queue_lock); | |
1164 | __cfq_exit_single_io_context(cfqd, cic); | |
1165 | spin_unlock_irq(q->queue_lock); | |
1166 | } | |
1167 | } | |
1168 | ||
1169 | static void cfq_exit_io_context(struct io_context *ioc) | |
1170 | { | |
1171 | struct cfq_io_context *__cic; | |
1172 | struct rb_node *n; | |
1173 | ||
1174 | /* | |
1175 | * put the reference this task is holding to the various queues | |
1176 | */ | |
1177 | ||
1178 | n = rb_first(&ioc->cic_root); | |
1179 | while (n != NULL) { | |
1180 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1181 | ||
1182 | cfq_exit_single_io_context(__cic); | |
1183 | n = rb_next(n); | |
1184 | } | |
1185 | } | |
1186 | ||
1187 | static struct cfq_io_context * | |
1188 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) | |
1189 | { | |
1190 | struct cfq_io_context *cic; | |
1191 | ||
1192 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask, cfqd->queue->node); | |
1193 | if (cic) { | |
1194 | memset(cic, 0, sizeof(*cic)); | |
1195 | cic->last_end_request = jiffies; | |
1196 | INIT_LIST_HEAD(&cic->queue_list); | |
1197 | cic->dtor = cfq_free_io_context; | |
1198 | cic->exit = cfq_exit_io_context; | |
1199 | elv_ioc_count_inc(ioc_count); | |
1200 | } | |
1201 | ||
1202 | return cic; | |
1203 | } | |
1204 | ||
1205 | static void cfq_init_prio_data(struct cfq_queue *cfqq) | |
1206 | { | |
1207 | struct task_struct *tsk = current; | |
1208 | int ioprio_class; | |
1209 | ||
1210 | if (!cfq_cfqq_prio_changed(cfqq)) | |
1211 | return; | |
1212 | ||
1213 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1214 | switch (ioprio_class) { | |
1215 | default: | |
1216 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1217 | case IOPRIO_CLASS_NONE: | |
1218 | /* | |
1219 | * no prio set, place us in the middle of the BE classes | |
1220 | */ | |
1221 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1222 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1223 | break; | |
1224 | case IOPRIO_CLASS_RT: | |
1225 | cfqq->ioprio = task_ioprio(tsk); | |
1226 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1227 | break; | |
1228 | case IOPRIO_CLASS_BE: | |
1229 | cfqq->ioprio = task_ioprio(tsk); | |
1230 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1231 | break; | |
1232 | case IOPRIO_CLASS_IDLE: | |
1233 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1234 | cfqq->ioprio = 7; | |
1235 | cfq_clear_cfqq_idle_window(cfqq); | |
1236 | break; | |
1237 | } | |
1238 | ||
1239 | /* | |
1240 | * keep track of original prio settings in case we have to temporarily | |
1241 | * elevate the priority of this queue | |
1242 | */ | |
1243 | cfqq->org_ioprio = cfqq->ioprio; | |
1244 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1245 | ||
1246 | if (cfq_cfqq_on_rr(cfqq)) | |
1247 | cfq_resort_rr_list(cfqq, 0); | |
1248 | ||
1249 | cfq_clear_cfqq_prio_changed(cfqq); | |
1250 | } | |
1251 | ||
1252 | static inline void changed_ioprio(struct cfq_io_context *cic) | |
1253 | { | |
1254 | struct cfq_data *cfqd = cic->key; | |
1255 | struct cfq_queue *cfqq; | |
1256 | unsigned long flags; | |
1257 | ||
1258 | if (unlikely(!cfqd)) | |
1259 | return; | |
1260 | ||
1261 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1262 | ||
1263 | cfqq = cic->cfqq[ASYNC]; | |
1264 | if (cfqq) { | |
1265 | struct cfq_queue *new_cfqq; | |
1266 | new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC, cic->ioc->task, | |
1267 | GFP_ATOMIC); | |
1268 | if (new_cfqq) { | |
1269 | cic->cfqq[ASYNC] = new_cfqq; | |
1270 | cfq_put_queue(cfqq); | |
1271 | } | |
1272 | } | |
1273 | ||
1274 | cfqq = cic->cfqq[SYNC]; | |
1275 | if (cfqq) | |
1276 | cfq_mark_cfqq_prio_changed(cfqq); | |
1277 | ||
1278 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1279 | } | |
1280 | ||
1281 | static void cfq_ioc_set_ioprio(struct io_context *ioc) | |
1282 | { | |
1283 | struct cfq_io_context *cic; | |
1284 | struct rb_node *n; | |
1285 | ||
1286 | ioc->ioprio_changed = 0; | |
1287 | ||
1288 | n = rb_first(&ioc->cic_root); | |
1289 | while (n != NULL) { | |
1290 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1291 | ||
1292 | changed_ioprio(cic); | |
1293 | n = rb_next(n); | |
1294 | } | |
1295 | } | |
1296 | ||
1297 | static struct cfq_queue * | |
1298 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, | |
1299 | gfp_t gfp_mask) | |
1300 | { | |
1301 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1302 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
1303 | unsigned short ioprio; | |
1304 | ||
1305 | retry: | |
1306 | ioprio = tsk->ioprio; | |
1307 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); | |
1308 | ||
1309 | if (!cfqq) { | |
1310 | if (new_cfqq) { | |
1311 | cfqq = new_cfqq; | |
1312 | new_cfqq = NULL; | |
1313 | } else if (gfp_mask & __GFP_WAIT) { | |
1314 | /* | |
1315 | * Inform the allocator of the fact that we will | |
1316 | * just repeat this allocation if it fails, to allow | |
1317 | * the allocator to do whatever it needs to attempt to | |
1318 | * free memory. | |
1319 | */ | |
1320 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1321 | new_cfqq = kmem_cache_alloc_node(cfq_pool, gfp_mask|__GFP_NOFAIL, cfqd->queue->node); | |
1322 | spin_lock_irq(cfqd->queue->queue_lock); | |
1323 | goto retry; | |
1324 | } else { | |
1325 | cfqq = kmem_cache_alloc_node(cfq_pool, gfp_mask, cfqd->queue->node); | |
1326 | if (!cfqq) | |
1327 | goto out; | |
1328 | } | |
1329 | ||
1330 | memset(cfqq, 0, sizeof(*cfqq)); | |
1331 | ||
1332 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1333 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
1334 | INIT_LIST_HEAD(&cfqq->fifo); | |
1335 | ||
1336 | cfqq->key = key; | |
1337 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1338 | atomic_set(&cfqq->ref, 0); | |
1339 | cfqq->cfqd = cfqd; | |
1340 | /* | |
1341 | * set ->slice_left to allow preemption for a new process | |
1342 | */ | |
1343 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
1344 | cfq_mark_cfqq_idle_window(cfqq); | |
1345 | cfq_mark_cfqq_prio_changed(cfqq); | |
1346 | cfq_mark_cfqq_queue_new(cfqq); | |
1347 | cfq_init_prio_data(cfqq); | |
1348 | } | |
1349 | ||
1350 | if (new_cfqq) | |
1351 | kmem_cache_free(cfq_pool, new_cfqq); | |
1352 | ||
1353 | atomic_inc(&cfqq->ref); | |
1354 | out: | |
1355 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1356 | return cfqq; | |
1357 | } | |
1358 | ||
1359 | static void | |
1360 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1361 | { | |
1362 | WARN_ON(!list_empty(&cic->queue_list)); | |
1363 | rb_erase(&cic->rb_node, &ioc->cic_root); | |
1364 | kmem_cache_free(cfq_ioc_pool, cic); | |
1365 | elv_ioc_count_dec(ioc_count); | |
1366 | } | |
1367 | ||
1368 | static struct cfq_io_context * | |
1369 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1370 | { | |
1371 | struct rb_node *n; | |
1372 | struct cfq_io_context *cic; | |
1373 | void *k, *key = cfqd; | |
1374 | ||
1375 | restart: | |
1376 | n = ioc->cic_root.rb_node; | |
1377 | while (n) { | |
1378 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1379 | /* ->key must be copied to avoid race with cfq_exit_queue() */ | |
1380 | k = cic->key; | |
1381 | if (unlikely(!k)) { | |
1382 | cfq_drop_dead_cic(ioc, cic); | |
1383 | goto restart; | |
1384 | } | |
1385 | ||
1386 | if (key < k) | |
1387 | n = n->rb_left; | |
1388 | else if (key > k) | |
1389 | n = n->rb_right; | |
1390 | else | |
1391 | return cic; | |
1392 | } | |
1393 | ||
1394 | return NULL; | |
1395 | } | |
1396 | ||
1397 | static inline void | |
1398 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1399 | struct cfq_io_context *cic) | |
1400 | { | |
1401 | struct rb_node **p; | |
1402 | struct rb_node *parent; | |
1403 | struct cfq_io_context *__cic; | |
1404 | unsigned long flags; | |
1405 | void *k; | |
1406 | ||
1407 | cic->ioc = ioc; | |
1408 | cic->key = cfqd; | |
1409 | ||
1410 | restart: | |
1411 | parent = NULL; | |
1412 | p = &ioc->cic_root.rb_node; | |
1413 | while (*p) { | |
1414 | parent = *p; | |
1415 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
1416 | /* ->key must be copied to avoid race with cfq_exit_queue() */ | |
1417 | k = __cic->key; | |
1418 | if (unlikely(!k)) { | |
1419 | cfq_drop_dead_cic(ioc, __cic); | |
1420 | goto restart; | |
1421 | } | |
1422 | ||
1423 | if (cic->key < k) | |
1424 | p = &(*p)->rb_left; | |
1425 | else if (cic->key > k) | |
1426 | p = &(*p)->rb_right; | |
1427 | else | |
1428 | BUG(); | |
1429 | } | |
1430 | ||
1431 | rb_link_node(&cic->rb_node, parent, p); | |
1432 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
1433 | ||
1434 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1435 | list_add(&cic->queue_list, &cfqd->cic_list); | |
1436 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1437 | } | |
1438 | ||
1439 | /* | |
1440 | * Setup general io context and cfq io context. There can be several cfq | |
1441 | * io contexts per general io context, if this process is doing io to more | |
1442 | * than one device managed by cfq. | |
1443 | */ | |
1444 | static struct cfq_io_context * | |
1445 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) | |
1446 | { | |
1447 | struct io_context *ioc = NULL; | |
1448 | struct cfq_io_context *cic; | |
1449 | ||
1450 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1451 | ||
1452 | ioc = get_io_context(gfp_mask, cfqd->queue->node); | |
1453 | if (!ioc) | |
1454 | return NULL; | |
1455 | ||
1456 | cic = cfq_cic_rb_lookup(cfqd, ioc); | |
1457 | if (cic) | |
1458 | goto out; | |
1459 | ||
1460 | cic = cfq_alloc_io_context(cfqd, gfp_mask); | |
1461 | if (cic == NULL) | |
1462 | goto err; | |
1463 | ||
1464 | cfq_cic_link(cfqd, ioc, cic); | |
1465 | out: | |
1466 | smp_read_barrier_depends(); | |
1467 | if (unlikely(ioc->ioprio_changed)) | |
1468 | cfq_ioc_set_ioprio(ioc); | |
1469 | ||
1470 | return cic; | |
1471 | err: | |
1472 | put_io_context(ioc); | |
1473 | return NULL; | |
1474 | } | |
1475 | ||
1476 | static void | |
1477 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1478 | { | |
1479 | unsigned long elapsed, ttime; | |
1480 | ||
1481 | /* | |
1482 | * if this context already has stuff queued, thinktime is from | |
1483 | * last queue not last end | |
1484 | */ | |
1485 | #if 0 | |
1486 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1487 | elapsed = jiffies - cic->last_end_request; | |
1488 | else | |
1489 | elapsed = jiffies - cic->last_queue; | |
1490 | #else | |
1491 | elapsed = jiffies - cic->last_end_request; | |
1492 | #endif | |
1493 | ||
1494 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
1495 | ||
1496 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; | |
1497 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1498 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1499 | } | |
1500 | ||
1501 | static void | |
1502 | cfq_update_io_seektime(struct cfq_io_context *cic, struct request *rq) | |
1503 | { | |
1504 | sector_t sdist; | |
1505 | u64 total; | |
1506 | ||
1507 | if (cic->last_request_pos < rq->sector) | |
1508 | sdist = rq->sector - cic->last_request_pos; | |
1509 | else | |
1510 | sdist = cic->last_request_pos - rq->sector; | |
1511 | ||
1512 | /* | |
1513 | * Don't allow the seek distance to get too large from the | |
1514 | * odd fragment, pagein, etc | |
1515 | */ | |
1516 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1517 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1518 | else | |
1519 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1520 | ||
1521 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1522 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1523 | total = cic->seek_total + (cic->seek_samples/2); | |
1524 | do_div(total, cic->seek_samples); | |
1525 | cic->seek_mean = (sector_t)total; | |
1526 | } | |
1527 | ||
1528 | /* | |
1529 | * Disable idle window if the process thinks too long or seeks so much that | |
1530 | * it doesn't matter | |
1531 | */ | |
1532 | static void | |
1533 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1534 | struct cfq_io_context *cic) | |
1535 | { | |
1536 | int enable_idle = cfq_cfqq_idle_window(cfqq); | |
1537 | ||
1538 | if (!cic->ioc->task || !cfqd->cfq_slice_idle || | |
1539 | (cfqd->hw_tag && CIC_SEEKY(cic))) | |
1540 | enable_idle = 0; | |
1541 | else if (sample_valid(cic->ttime_samples)) { | |
1542 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1543 | enable_idle = 0; | |
1544 | else | |
1545 | enable_idle = 1; | |
1546 | } | |
1547 | ||
1548 | if (enable_idle) | |
1549 | cfq_mark_cfqq_idle_window(cfqq); | |
1550 | else | |
1551 | cfq_clear_cfqq_idle_window(cfqq); | |
1552 | } | |
1553 | ||
1554 | ||
1555 | /* | |
1556 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1557 | * no or if we aren't sure, a 1 will cause a preempt. | |
1558 | */ | |
1559 | static int | |
1560 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1561 | struct request *rq) | |
1562 | { | |
1563 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1564 | ||
1565 | if (cfq_class_idle(new_cfqq)) | |
1566 | return 0; | |
1567 | ||
1568 | if (!cfqq) | |
1569 | return 0; | |
1570 | ||
1571 | if (cfq_class_idle(cfqq)) | |
1572 | return 1; | |
1573 | if (!cfq_cfqq_wait_request(new_cfqq)) | |
1574 | return 0; | |
1575 | /* | |
1576 | * if it doesn't have slice left, forget it | |
1577 | */ | |
1578 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1579 | return 0; | |
1580 | /* | |
1581 | * if the new request is sync, but the currently running queue is | |
1582 | * not, let the sync request have priority. | |
1583 | */ | |
1584 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) | |
1585 | return 1; | |
1586 | /* | |
1587 | * So both queues are sync. Let the new request get disk time if | |
1588 | * it's a metadata request and the current queue is doing regular IO. | |
1589 | */ | |
1590 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
1591 | return 1; | |
1592 | ||
1593 | return 0; | |
1594 | } | |
1595 | ||
1596 | /* | |
1597 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1598 | * let it have half of its nominal slice. | |
1599 | */ | |
1600 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1601 | { | |
1602 | cfq_slice_expired(cfqd, 1); | |
1603 | ||
1604 | if (!cfqq->slice_left) | |
1605 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1606 | ||
1607 | /* | |
1608 | * Put the new queue at the front of the of the current list, | |
1609 | * so we know that it will be selected next. | |
1610 | */ | |
1611 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
1612 | list_move(&cfqq->cfq_list, &cfqd->cur_rr); | |
1613 | ||
1614 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
1615 | } | |
1616 | ||
1617 | /* | |
1618 | * Called when a new fs request (rq) is added (to cfqq). Check if there's | |
1619 | * something we should do about it | |
1620 | */ | |
1621 | static void | |
1622 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1623 | struct request *rq) | |
1624 | { | |
1625 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1626 | ||
1627 | if (rq_is_meta(rq)) | |
1628 | cfqq->meta_pending++; | |
1629 | ||
1630 | /* | |
1631 | * check if this request is a better next-serve candidate)) { | |
1632 | */ | |
1633 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); | |
1634 | BUG_ON(!cfqq->next_rq); | |
1635 | ||
1636 | /* | |
1637 | * we never wait for an async request and we don't allow preemption | |
1638 | * of an async request. so just return early | |
1639 | */ | |
1640 | if (!rq_is_sync(rq)) { | |
1641 | /* | |
1642 | * sync process issued an async request, if it's waiting | |
1643 | * then expire it and kick rq handling. | |
1644 | */ | |
1645 | if (cic == cfqd->active_cic && | |
1646 | del_timer(&cfqd->idle_slice_timer)) { | |
1647 | cfq_slice_expired(cfqd, 0); | |
1648 | blk_start_queueing(cfqd->queue); | |
1649 | } | |
1650 | return; | |
1651 | } | |
1652 | ||
1653 | cfq_update_io_thinktime(cfqd, cic); | |
1654 | cfq_update_io_seektime(cic, rq); | |
1655 | cfq_update_idle_window(cfqd, cfqq, cic); | |
1656 | ||
1657 | cic->last_queue = jiffies; | |
1658 | cic->last_request_pos = rq->sector + rq->nr_sectors; | |
1659 | ||
1660 | if (cfqq == cfqd->active_queue) { | |
1661 | /* | |
1662 | * if we are waiting for a request for this queue, let it rip | |
1663 | * immediately and flag that we must not expire this queue | |
1664 | * just now | |
1665 | */ | |
1666 | if (cfq_cfqq_wait_request(cfqq)) { | |
1667 | cfq_mark_cfqq_must_dispatch(cfqq); | |
1668 | del_timer(&cfqd->idle_slice_timer); | |
1669 | blk_start_queueing(cfqd->queue); | |
1670 | } | |
1671 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { | |
1672 | /* | |
1673 | * not the active queue - expire current slice if it is | |
1674 | * idle and has expired it's mean thinktime or this new queue | |
1675 | * has some old slice time left and is of higher priority | |
1676 | */ | |
1677 | cfq_preempt_queue(cfqd, cfqq); | |
1678 | cfq_mark_cfqq_must_dispatch(cfqq); | |
1679 | blk_start_queueing(cfqd->queue); | |
1680 | } | |
1681 | } | |
1682 | ||
1683 | static void cfq_insert_request(request_queue_t *q, struct request *rq) | |
1684 | { | |
1685 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1686 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1687 | ||
1688 | cfq_init_prio_data(cfqq); | |
1689 | ||
1690 | cfq_add_rq_rb(rq); | |
1691 | ||
1692 | list_add_tail(&rq->queuelist, &cfqq->fifo); | |
1693 | ||
1694 | cfq_rq_enqueued(cfqd, cfqq, rq); | |
1695 | } | |
1696 | ||
1697 | static void cfq_completed_request(request_queue_t *q, struct request *rq) | |
1698 | { | |
1699 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1700 | struct cfq_data *cfqd = cfqq->cfqd; | |
1701 | const int sync = rq_is_sync(rq); | |
1702 | unsigned long now; | |
1703 | ||
1704 | now = jiffies; | |
1705 | ||
1706 | WARN_ON(!cfqd->rq_in_driver); | |
1707 | WARN_ON(!cfqq->on_dispatch[sync]); | |
1708 | cfqd->rq_in_driver--; | |
1709 | cfqq->on_dispatch[sync]--; | |
1710 | ||
1711 | if (!cfq_class_idle(cfqq)) | |
1712 | cfqd->last_end_request = now; | |
1713 | ||
1714 | if (!cfq_cfqq_dispatched(cfqq) && cfq_cfqq_on_rr(cfqq)) | |
1715 | cfq_resort_rr_list(cfqq, 0); | |
1716 | ||
1717 | if (sync) | |
1718 | RQ_CIC(rq)->last_end_request = now; | |
1719 | ||
1720 | /* | |
1721 | * If this is the active queue, check if it needs to be expired, | |
1722 | * or if we want to idle in case it has no pending requests. | |
1723 | */ | |
1724 | if (cfqd->active_queue == cfqq) { | |
1725 | if (time_after(now, cfqq->slice_end)) | |
1726 | cfq_slice_expired(cfqd, 0); | |
1727 | else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) { | |
1728 | if (!cfq_arm_slice_timer(cfqd, cfqq)) | |
1729 | cfq_schedule_dispatch(cfqd); | |
1730 | } | |
1731 | } | |
1732 | } | |
1733 | ||
1734 | /* | |
1735 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1736 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1737 | */ | |
1738 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1739 | { | |
1740 | const int ioprio_class = cfqq->ioprio_class; | |
1741 | const int ioprio = cfqq->ioprio; | |
1742 | ||
1743 | if (has_fs_excl()) { | |
1744 | /* | |
1745 | * boost idle prio on transactions that would lock out other | |
1746 | * users of the filesystem | |
1747 | */ | |
1748 | if (cfq_class_idle(cfqq)) | |
1749 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1750 | if (cfqq->ioprio > IOPRIO_NORM) | |
1751 | cfqq->ioprio = IOPRIO_NORM; | |
1752 | } else { | |
1753 | /* | |
1754 | * check if we need to unboost the queue | |
1755 | */ | |
1756 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1757 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1758 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1759 | cfqq->ioprio = cfqq->org_ioprio; | |
1760 | } | |
1761 | ||
1762 | /* | |
1763 | * refile between round-robin lists if we moved the priority class | |
1764 | */ | |
1765 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
1766 | cfq_cfqq_on_rr(cfqq)) | |
1767 | cfq_resort_rr_list(cfqq, 0); | |
1768 | } | |
1769 | ||
1770 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) | |
1771 | { | |
1772 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && | |
1773 | !cfq_cfqq_must_alloc_slice(cfqq)) { | |
1774 | cfq_mark_cfqq_must_alloc_slice(cfqq); | |
1775 | return ELV_MQUEUE_MUST; | |
1776 | } | |
1777 | ||
1778 | return ELV_MQUEUE_MAY; | |
1779 | } | |
1780 | ||
1781 | static int cfq_may_queue(request_queue_t *q, int rw) | |
1782 | { | |
1783 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1784 | struct task_struct *tsk = current; | |
1785 | struct cfq_queue *cfqq; | |
1786 | unsigned int key; | |
1787 | ||
1788 | key = cfq_queue_pid(tsk, rw, rw & REQ_RW_SYNC); | |
1789 | ||
1790 | /* | |
1791 | * don't force setup of a queue from here, as a call to may_queue | |
1792 | * does not necessarily imply that a request actually will be queued. | |
1793 | * so just lookup a possibly existing queue, or return 'may queue' | |
1794 | * if that fails | |
1795 | */ | |
1796 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); | |
1797 | if (cfqq) { | |
1798 | cfq_init_prio_data(cfqq); | |
1799 | cfq_prio_boost(cfqq); | |
1800 | ||
1801 | return __cfq_may_queue(cfqq); | |
1802 | } | |
1803 | ||
1804 | return ELV_MQUEUE_MAY; | |
1805 | } | |
1806 | ||
1807 | /* | |
1808 | * queue lock held here | |
1809 | */ | |
1810 | static void cfq_put_request(struct request *rq) | |
1811 | { | |
1812 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1813 | ||
1814 | if (cfqq) { | |
1815 | const int rw = rq_data_dir(rq); | |
1816 | ||
1817 | BUG_ON(!cfqq->allocated[rw]); | |
1818 | cfqq->allocated[rw]--; | |
1819 | ||
1820 | put_io_context(RQ_CIC(rq)->ioc); | |
1821 | ||
1822 | rq->elevator_private = NULL; | |
1823 | rq->elevator_private2 = NULL; | |
1824 | ||
1825 | cfq_put_queue(cfqq); | |
1826 | } | |
1827 | } | |
1828 | ||
1829 | /* | |
1830 | * Allocate cfq data structures associated with this request. | |
1831 | */ | |
1832 | static int | |
1833 | cfq_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) | |
1834 | { | |
1835 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1836 | struct task_struct *tsk = current; | |
1837 | struct cfq_io_context *cic; | |
1838 | const int rw = rq_data_dir(rq); | |
1839 | const int is_sync = rq_is_sync(rq); | |
1840 | pid_t key = cfq_queue_pid(tsk, rw, is_sync); | |
1841 | struct cfq_queue *cfqq; | |
1842 | unsigned long flags; | |
1843 | ||
1844 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1845 | ||
1846 | cic = cfq_get_io_context(cfqd, gfp_mask); | |
1847 | ||
1848 | spin_lock_irqsave(q->queue_lock, flags); | |
1849 | ||
1850 | if (!cic) | |
1851 | goto queue_fail; | |
1852 | ||
1853 | if (!cic->cfqq[is_sync]) { | |
1854 | cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask); | |
1855 | if (!cfqq) | |
1856 | goto queue_fail; | |
1857 | ||
1858 | cic->cfqq[is_sync] = cfqq; | |
1859 | } else | |
1860 | cfqq = cic->cfqq[is_sync]; | |
1861 | ||
1862 | cfqq->allocated[rw]++; | |
1863 | cfq_clear_cfqq_must_alloc(cfqq); | |
1864 | atomic_inc(&cfqq->ref); | |
1865 | ||
1866 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1867 | ||
1868 | rq->elevator_private = cic; | |
1869 | rq->elevator_private2 = cfqq; | |
1870 | return 0; | |
1871 | ||
1872 | queue_fail: | |
1873 | if (cic) | |
1874 | put_io_context(cic->ioc); | |
1875 | ||
1876 | cfq_schedule_dispatch(cfqd); | |
1877 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1878 | return 1; | |
1879 | } | |
1880 | ||
1881 | static void cfq_kick_queue(struct work_struct *work) | |
1882 | { | |
1883 | struct cfq_data *cfqd = | |
1884 | container_of(work, struct cfq_data, unplug_work); | |
1885 | request_queue_t *q = cfqd->queue; | |
1886 | unsigned long flags; | |
1887 | ||
1888 | spin_lock_irqsave(q->queue_lock, flags); | |
1889 | blk_start_queueing(q); | |
1890 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1891 | } | |
1892 | ||
1893 | /* | |
1894 | * Timer running if the active_queue is currently idling inside its time slice | |
1895 | */ | |
1896 | static void cfq_idle_slice_timer(unsigned long data) | |
1897 | { | |
1898 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
1899 | struct cfq_queue *cfqq; | |
1900 | unsigned long flags; | |
1901 | ||
1902 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1903 | ||
1904 | if ((cfqq = cfqd->active_queue) != NULL) { | |
1905 | unsigned long now = jiffies; | |
1906 | ||
1907 | /* | |
1908 | * expired | |
1909 | */ | |
1910 | if (time_after(now, cfqq->slice_end)) | |
1911 | goto expire; | |
1912 | ||
1913 | /* | |
1914 | * only expire and reinvoke request handler, if there are | |
1915 | * other queues with pending requests | |
1916 | */ | |
1917 | if (!cfqd->busy_queues) | |
1918 | goto out_cont; | |
1919 | ||
1920 | /* | |
1921 | * not expired and it has a request pending, let it dispatch | |
1922 | */ | |
1923 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) { | |
1924 | cfq_mark_cfqq_must_dispatch(cfqq); | |
1925 | goto out_kick; | |
1926 | } | |
1927 | } | |
1928 | expire: | |
1929 | cfq_slice_expired(cfqd, 0); | |
1930 | out_kick: | |
1931 | cfq_schedule_dispatch(cfqd); | |
1932 | out_cont: | |
1933 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1934 | } | |
1935 | ||
1936 | /* | |
1937 | * Timer running if an idle class queue is waiting for service | |
1938 | */ | |
1939 | static void cfq_idle_class_timer(unsigned long data) | |
1940 | { | |
1941 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
1942 | unsigned long flags, end; | |
1943 | ||
1944 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1945 | ||
1946 | /* | |
1947 | * race with a non-idle queue, reset timer | |
1948 | */ | |
1949 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
1950 | if (!time_after_eq(jiffies, end)) | |
1951 | mod_timer(&cfqd->idle_class_timer, end); | |
1952 | else | |
1953 | cfq_schedule_dispatch(cfqd); | |
1954 | ||
1955 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1956 | } | |
1957 | ||
1958 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) | |
1959 | { | |
1960 | del_timer_sync(&cfqd->idle_slice_timer); | |
1961 | del_timer_sync(&cfqd->idle_class_timer); | |
1962 | blk_sync_queue(cfqd->queue); | |
1963 | } | |
1964 | ||
1965 | static void cfq_exit_queue(elevator_t *e) | |
1966 | { | |
1967 | struct cfq_data *cfqd = e->elevator_data; | |
1968 | request_queue_t *q = cfqd->queue; | |
1969 | ||
1970 | cfq_shutdown_timer_wq(cfqd); | |
1971 | ||
1972 | spin_lock_irq(q->queue_lock); | |
1973 | ||
1974 | if (cfqd->active_queue) | |
1975 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); | |
1976 | ||
1977 | while (!list_empty(&cfqd->cic_list)) { | |
1978 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, | |
1979 | struct cfq_io_context, | |
1980 | queue_list); | |
1981 | ||
1982 | __cfq_exit_single_io_context(cfqd, cic); | |
1983 | } | |
1984 | ||
1985 | spin_unlock_irq(q->queue_lock); | |
1986 | ||
1987 | cfq_shutdown_timer_wq(cfqd); | |
1988 | ||
1989 | kfree(cfqd->cfq_hash); | |
1990 | kfree(cfqd); | |
1991 | } | |
1992 | ||
1993 | static void *cfq_init_queue(request_queue_t *q) | |
1994 | { | |
1995 | struct cfq_data *cfqd; | |
1996 | int i; | |
1997 | ||
1998 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node); | |
1999 | if (!cfqd) | |
2000 | return NULL; | |
2001 | ||
2002 | memset(cfqd, 0, sizeof(*cfqd)); | |
2003 | ||
2004 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2005 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2006 | ||
2007 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2008 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2009 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
2010 | INIT_LIST_HEAD(&cfqd->cic_list); | |
2011 | ||
2012 | cfqd->cfq_hash = kmalloc_node(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL, q->node); | |
2013 | if (!cfqd->cfq_hash) | |
2014 | goto out_free; | |
2015 | ||
2016 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2017 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2018 | ||
2019 | cfqd->queue = q; | |
2020 | ||
2021 | init_timer(&cfqd->idle_slice_timer); | |
2022 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2023 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2024 | ||
2025 | init_timer(&cfqd->idle_class_timer); | |
2026 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2027 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2028 | ||
2029 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); | |
2030 | ||
2031 | cfqd->cfq_quantum = cfq_quantum; | |
2032 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; | |
2033 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
2034 | cfqd->cfq_back_max = cfq_back_max; | |
2035 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
2036 | cfqd->cfq_slice[0] = cfq_slice_async; | |
2037 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2038 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2039 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
2040 | ||
2041 | return cfqd; | |
2042 | out_free: | |
2043 | kfree(cfqd); | |
2044 | return NULL; | |
2045 | } | |
2046 | ||
2047 | static void cfq_slab_kill(void) | |
2048 | { | |
2049 | if (cfq_pool) | |
2050 | kmem_cache_destroy(cfq_pool); | |
2051 | if (cfq_ioc_pool) | |
2052 | kmem_cache_destroy(cfq_ioc_pool); | |
2053 | } | |
2054 | ||
2055 | static int __init cfq_slab_setup(void) | |
2056 | { | |
2057 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2058 | NULL, NULL); | |
2059 | if (!cfq_pool) | |
2060 | goto fail; | |
2061 | ||
2062 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2063 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2064 | if (!cfq_ioc_pool) | |
2065 | goto fail; | |
2066 | ||
2067 | return 0; | |
2068 | fail: | |
2069 | cfq_slab_kill(); | |
2070 | return -ENOMEM; | |
2071 | } | |
2072 | ||
2073 | /* | |
2074 | * sysfs parts below --> | |
2075 | */ | |
2076 | ||
2077 | static ssize_t | |
2078 | cfq_var_show(unsigned int var, char *page) | |
2079 | { | |
2080 | return sprintf(page, "%d\n", var); | |
2081 | } | |
2082 | ||
2083 | static ssize_t | |
2084 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2085 | { | |
2086 | char *p = (char *) page; | |
2087 | ||
2088 | *var = simple_strtoul(p, &p, 10); | |
2089 | return count; | |
2090 | } | |
2091 | ||
2092 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
2093 | static ssize_t __FUNC(elevator_t *e, char *page) \ | |
2094 | { \ | |
2095 | struct cfq_data *cfqd = e->elevator_data; \ | |
2096 | unsigned int __data = __VAR; \ | |
2097 | if (__CONV) \ | |
2098 | __data = jiffies_to_msecs(__data); \ | |
2099 | return cfq_var_show(__data, (page)); \ | |
2100 | } | |
2101 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2102 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); | |
2103 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
2104 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); | |
2105 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
2106 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); | |
2107 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2108 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2109 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
2110 | #undef SHOW_FUNCTION | |
2111 | ||
2112 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
2113 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ | |
2114 | { \ | |
2115 | struct cfq_data *cfqd = e->elevator_data; \ | |
2116 | unsigned int __data; \ | |
2117 | int ret = cfq_var_store(&__data, (page), count); \ | |
2118 | if (__data < (MIN)) \ | |
2119 | __data = (MIN); \ | |
2120 | else if (__data > (MAX)) \ | |
2121 | __data = (MAX); \ | |
2122 | if (__CONV) \ | |
2123 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2124 | else \ | |
2125 | *(__PTR) = __data; \ | |
2126 | return ret; \ | |
2127 | } | |
2128 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2129 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); | |
2130 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
2131 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); | |
2132 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
2133 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); | |
2134 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2135 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2136 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
2137 | #undef STORE_FUNCTION | |
2138 | ||
2139 | #define CFQ_ATTR(name) \ | |
2140 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2141 | ||
2142 | static struct elv_fs_entry cfq_attrs[] = { | |
2143 | CFQ_ATTR(quantum), | |
2144 | CFQ_ATTR(fifo_expire_sync), | |
2145 | CFQ_ATTR(fifo_expire_async), | |
2146 | CFQ_ATTR(back_seek_max), | |
2147 | CFQ_ATTR(back_seek_penalty), | |
2148 | CFQ_ATTR(slice_sync), | |
2149 | CFQ_ATTR(slice_async), | |
2150 | CFQ_ATTR(slice_async_rq), | |
2151 | CFQ_ATTR(slice_idle), | |
2152 | __ATTR_NULL | |
2153 | }; | |
2154 | ||
2155 | static struct elevator_type iosched_cfq = { | |
2156 | .ops = { | |
2157 | .elevator_merge_fn = cfq_merge, | |
2158 | .elevator_merged_fn = cfq_merged_request, | |
2159 | .elevator_merge_req_fn = cfq_merged_requests, | |
2160 | .elevator_allow_merge_fn = cfq_allow_merge, | |
2161 | .elevator_dispatch_fn = cfq_dispatch_requests, | |
2162 | .elevator_add_req_fn = cfq_insert_request, | |
2163 | .elevator_activate_req_fn = cfq_activate_request, | |
2164 | .elevator_deactivate_req_fn = cfq_deactivate_request, | |
2165 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2166 | .elevator_completed_req_fn = cfq_completed_request, | |
2167 | .elevator_former_req_fn = elv_rb_former_request, | |
2168 | .elevator_latter_req_fn = elv_rb_latter_request, | |
2169 | .elevator_set_req_fn = cfq_set_request, | |
2170 | .elevator_put_req_fn = cfq_put_request, | |
2171 | .elevator_may_queue_fn = cfq_may_queue, | |
2172 | .elevator_init_fn = cfq_init_queue, | |
2173 | .elevator_exit_fn = cfq_exit_queue, | |
2174 | .trim = cfq_free_io_context, | |
2175 | }, | |
2176 | .elevator_attrs = cfq_attrs, | |
2177 | .elevator_name = "cfq", | |
2178 | .elevator_owner = THIS_MODULE, | |
2179 | }; | |
2180 | ||
2181 | static int __init cfq_init(void) | |
2182 | { | |
2183 | int ret; | |
2184 | ||
2185 | /* | |
2186 | * could be 0 on HZ < 1000 setups | |
2187 | */ | |
2188 | if (!cfq_slice_async) | |
2189 | cfq_slice_async = 1; | |
2190 | if (!cfq_slice_idle) | |
2191 | cfq_slice_idle = 1; | |
2192 | ||
2193 | if (cfq_slab_setup()) | |
2194 | return -ENOMEM; | |
2195 | ||
2196 | ret = elv_register(&iosched_cfq); | |
2197 | if (ret) | |
2198 | cfq_slab_kill(); | |
2199 | ||
2200 | return ret; | |
2201 | } | |
2202 | ||
2203 | static void __exit cfq_exit(void) | |
2204 | { | |
2205 | DECLARE_COMPLETION_ONSTACK(all_gone); | |
2206 | elv_unregister(&iosched_cfq); | |
2207 | ioc_gone = &all_gone; | |
2208 | /* ioc_gone's update must be visible before reading ioc_count */ | |
2209 | smp_wmb(); | |
2210 | if (elv_ioc_count_read(ioc_count)) | |
2211 | wait_for_completion(ioc_gone); | |
2212 | synchronize_rcu(); | |
2213 | cfq_slab_kill(); | |
2214 | } | |
2215 | ||
2216 | module_init(cfq_init); | |
2217 | module_exit(cfq_exit); | |
2218 | ||
2219 | MODULE_AUTHOR("Jens Axboe"); | |
2220 | MODULE_LICENSE("GPL"); | |
2221 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |