Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
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@suse.de> | |
8 | */ | |
1da177e4 LT |
9 | #include <linux/config.h> |
10 | #include <linux/module.h> | |
1cc9be68 AV |
11 | #include <linux/blkdev.h> |
12 | #include <linux/elevator.h> | |
1da177e4 LT |
13 | #include <linux/hash.h> |
14 | #include <linux/rbtree.h> | |
22e2c507 | 15 | #include <linux/ioprio.h> |
1da177e4 LT |
16 | |
17 | /* | |
18 | * tunables | |
19 | */ | |
64100099 AV |
20 | static const int cfq_quantum = 4; /* max queue in one round of service */ |
21 | static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ | |
22 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; | |
23 | static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ | |
24 | static const int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
1da177e4 | 25 | |
64100099 | 26 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 27 | static int cfq_slice_async = HZ / 25; |
64100099 | 28 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 29 | static int cfq_slice_idle = HZ / 125; |
22e2c507 JA |
30 | |
31 | #define CFQ_IDLE_GRACE (HZ / 10) | |
32 | #define CFQ_SLICE_SCALE (5) | |
33 | ||
34 | #define CFQ_KEY_ASYNC (0) | |
22e2c507 | 35 | |
3793c65c | 36 | static DEFINE_SPINLOCK(cfq_exit_lock); |
a6a0763a | 37 | |
1da177e4 LT |
38 | /* |
39 | * for the hash of cfqq inside the cfqd | |
40 | */ | |
41 | #define CFQ_QHASH_SHIFT 6 | |
42 | #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) | |
43 | #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) | |
44 | ||
45 | /* | |
46 | * for the hash of crq inside the cfqq | |
47 | */ | |
48 | #define CFQ_MHASH_SHIFT 6 | |
49 | #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) | |
50 | #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) | |
51 | #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) | |
52 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
53 | #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) | |
54 | ||
55 | #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) | |
22e2c507 | 56 | #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) |
1da177e4 LT |
57 | |
58 | #define RQ_DATA(rq) (rq)->elevator_private | |
59 | ||
60 | /* | |
61 | * rb-tree defines | |
62 | */ | |
1da177e4 LT |
63 | #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) |
64 | #define rq_rb_key(rq) (rq)->sector | |
65 | ||
1da177e4 LT |
66 | static kmem_cache_t *crq_pool; |
67 | static kmem_cache_t *cfq_pool; | |
68 | static kmem_cache_t *cfq_ioc_pool; | |
69 | ||
334e94de AV |
70 | static atomic_t ioc_count = ATOMIC_INIT(0); |
71 | static struct completion *ioc_gone; | |
72 | ||
22e2c507 JA |
73 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
74 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
75 | #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) | |
76 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
77 | ||
3b18152c JA |
78 | #define ASYNC (0) |
79 | #define SYNC (1) | |
80 | ||
81 | #define cfq_cfqq_dispatched(cfqq) \ | |
82 | ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) | |
83 | ||
84 | #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) | |
85 | ||
86 | #define cfq_cfqq_sync(cfqq) \ | |
87 | (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) | |
22e2c507 | 88 | |
206dc69b JA |
89 | #define sample_valid(samples) ((samples) > 80) |
90 | ||
22e2c507 JA |
91 | /* |
92 | * Per block device queue structure | |
93 | */ | |
1da177e4 | 94 | struct cfq_data { |
22e2c507 JA |
95 | request_queue_t *queue; |
96 | ||
97 | /* | |
98 | * rr list of queues with requests and the count of them | |
99 | */ | |
100 | struct list_head rr_list[CFQ_PRIO_LISTS]; | |
101 | struct list_head busy_rr; | |
102 | struct list_head cur_rr; | |
103 | struct list_head idle_rr; | |
104 | unsigned int busy_queues; | |
105 | ||
106 | /* | |
107 | * non-ordered list of empty cfqq's | |
108 | */ | |
1da177e4 LT |
109 | struct list_head empty_list; |
110 | ||
22e2c507 JA |
111 | /* |
112 | * cfqq lookup hash | |
113 | */ | |
1da177e4 | 114 | struct hlist_head *cfq_hash; |
1da177e4 | 115 | |
22e2c507 JA |
116 | /* |
117 | * global crq hash for all queues | |
118 | */ | |
119 | struct hlist_head *crq_hash; | |
1da177e4 | 120 | |
22e2c507 | 121 | mempool_t *crq_pool; |
1da177e4 | 122 | |
22e2c507 | 123 | int rq_in_driver; |
25776e35 | 124 | int hw_tag; |
1da177e4 | 125 | |
22e2c507 JA |
126 | /* |
127 | * schedule slice state info | |
128 | */ | |
129 | /* | |
130 | * idle window management | |
131 | */ | |
132 | struct timer_list idle_slice_timer; | |
133 | struct work_struct unplug_work; | |
1da177e4 | 134 | |
22e2c507 JA |
135 | struct cfq_queue *active_queue; |
136 | struct cfq_io_context *active_cic; | |
137 | int cur_prio, cur_end_prio; | |
138 | unsigned int dispatch_slice; | |
139 | ||
140 | struct timer_list idle_class_timer; | |
1da177e4 LT |
141 | |
142 | sector_t last_sector; | |
22e2c507 | 143 | unsigned long last_end_request; |
1da177e4 | 144 | |
22e2c507 | 145 | unsigned int rq_starved; |
1da177e4 LT |
146 | |
147 | /* | |
148 | * tunables, see top of file | |
149 | */ | |
150 | unsigned int cfq_quantum; | |
151 | unsigned int cfq_queued; | |
22e2c507 | 152 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
153 | unsigned int cfq_back_penalty; |
154 | unsigned int cfq_back_max; | |
22e2c507 JA |
155 | unsigned int cfq_slice[2]; |
156 | unsigned int cfq_slice_async_rq; | |
157 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
158 | |
159 | struct list_head cic_list; | |
1da177e4 LT |
160 | }; |
161 | ||
22e2c507 JA |
162 | /* |
163 | * Per process-grouping structure | |
164 | */ | |
1da177e4 LT |
165 | struct cfq_queue { |
166 | /* reference count */ | |
167 | atomic_t ref; | |
168 | /* parent cfq_data */ | |
169 | struct cfq_data *cfqd; | |
22e2c507 | 170 | /* cfqq lookup hash */ |
1da177e4 LT |
171 | struct hlist_node cfq_hash; |
172 | /* hash key */ | |
22e2c507 | 173 | unsigned int key; |
1da177e4 LT |
174 | /* on either rr or empty list of cfqd */ |
175 | struct list_head cfq_list; | |
176 | /* sorted list of pending requests */ | |
177 | struct rb_root sort_list; | |
178 | /* if fifo isn't expired, next request to serve */ | |
179 | struct cfq_rq *next_crq; | |
180 | /* requests queued in sort_list */ | |
181 | int queued[2]; | |
182 | /* currently allocated requests */ | |
183 | int allocated[2]; | |
184 | /* fifo list of requests in sort_list */ | |
22e2c507 | 185 | struct list_head fifo; |
1da177e4 | 186 | |
22e2c507 JA |
187 | unsigned long slice_start; |
188 | unsigned long slice_end; | |
189 | unsigned long slice_left; | |
190 | unsigned long service_last; | |
1da177e4 | 191 | |
3b18152c JA |
192 | /* number of requests that are on the dispatch list */ |
193 | int on_dispatch[2]; | |
22e2c507 JA |
194 | |
195 | /* io prio of this group */ | |
196 | unsigned short ioprio, org_ioprio; | |
197 | unsigned short ioprio_class, org_ioprio_class; | |
198 | ||
3b18152c JA |
199 | /* various state flags, see below */ |
200 | unsigned int flags; | |
1da177e4 LT |
201 | }; |
202 | ||
203 | struct cfq_rq { | |
204 | struct rb_node rb_node; | |
205 | sector_t rb_key; | |
206 | struct request *request; | |
207 | struct hlist_node hash; | |
208 | ||
209 | struct cfq_queue *cfq_queue; | |
210 | struct cfq_io_context *io_context; | |
211 | ||
3b18152c | 212 | unsigned int crq_flags; |
1da177e4 LT |
213 | }; |
214 | ||
3b18152c JA |
215 | enum cfqq_state_flags { |
216 | CFQ_CFQQ_FLAG_on_rr = 0, | |
217 | CFQ_CFQQ_FLAG_wait_request, | |
218 | CFQ_CFQQ_FLAG_must_alloc, | |
219 | CFQ_CFQQ_FLAG_must_alloc_slice, | |
220 | CFQ_CFQQ_FLAG_must_dispatch, | |
221 | CFQ_CFQQ_FLAG_fifo_expire, | |
222 | CFQ_CFQQ_FLAG_idle_window, | |
223 | CFQ_CFQQ_FLAG_prio_changed, | |
3b18152c JA |
224 | }; |
225 | ||
226 | #define CFQ_CFQQ_FNS(name) \ | |
227 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
228 | { \ | |
229 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
230 | } \ | |
231 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
232 | { \ | |
233 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
234 | } \ | |
235 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
236 | { \ | |
237 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
238 | } | |
239 | ||
240 | CFQ_CFQQ_FNS(on_rr); | |
241 | CFQ_CFQQ_FNS(wait_request); | |
242 | CFQ_CFQQ_FNS(must_alloc); | |
243 | CFQ_CFQQ_FNS(must_alloc_slice); | |
244 | CFQ_CFQQ_FNS(must_dispatch); | |
245 | CFQ_CFQQ_FNS(fifo_expire); | |
246 | CFQ_CFQQ_FNS(idle_window); | |
247 | CFQ_CFQQ_FNS(prio_changed); | |
3b18152c JA |
248 | #undef CFQ_CFQQ_FNS |
249 | ||
250 | enum cfq_rq_state_flags { | |
b4878f24 | 251 | CFQ_CRQ_FLAG_is_sync = 0, |
3b18152c JA |
252 | }; |
253 | ||
254 | #define CFQ_CRQ_FNS(name) \ | |
255 | static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ | |
256 | { \ | |
257 | crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ | |
258 | } \ | |
259 | static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ | |
260 | { \ | |
261 | crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ | |
262 | } \ | |
263 | static inline int cfq_crq_##name(const struct cfq_rq *crq) \ | |
264 | { \ | |
265 | return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ | |
266 | } | |
267 | ||
3b18152c | 268 | CFQ_CRQ_FNS(is_sync); |
3b18152c JA |
269 | #undef CFQ_CRQ_FNS |
270 | ||
271 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); | |
b4878f24 | 272 | static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); |
6f325a13 | 273 | static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); |
1da177e4 | 274 | |
1da177e4 LT |
275 | /* |
276 | * lots of deadline iosched dupes, can be abstracted later... | |
277 | */ | |
278 | static inline void cfq_del_crq_hash(struct cfq_rq *crq) | |
279 | { | |
280 | hlist_del_init(&crq->hash); | |
281 | } | |
282 | ||
1da177e4 LT |
283 | static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) |
284 | { | |
285 | const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); | |
286 | ||
1da177e4 LT |
287 | hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); |
288 | } | |
289 | ||
290 | static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) | |
291 | { | |
292 | struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; | |
293 | struct hlist_node *entry, *next; | |
294 | ||
295 | hlist_for_each_safe(entry, next, hash_list) { | |
296 | struct cfq_rq *crq = list_entry_hash(entry); | |
297 | struct request *__rq = crq->request; | |
298 | ||
1da177e4 LT |
299 | if (!rq_mergeable(__rq)) { |
300 | cfq_del_crq_hash(crq); | |
301 | continue; | |
302 | } | |
303 | ||
304 | if (rq_hash_key(__rq) == offset) | |
305 | return __rq; | |
306 | } | |
307 | ||
308 | return NULL; | |
309 | } | |
310 | ||
99f95e52 AM |
311 | /* |
312 | * scheduler run of queue, if there are requests pending and no one in the | |
313 | * driver that will restart queueing | |
314 | */ | |
315 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
316 | { | |
7b14e3b5 | 317 | if (cfqd->busy_queues) |
99f95e52 AM |
318 | kblockd_schedule_work(&cfqd->unplug_work); |
319 | } | |
320 | ||
321 | static int cfq_queue_empty(request_queue_t *q) | |
322 | { | |
323 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
324 | ||
b4878f24 | 325 | return !cfqd->busy_queues; |
99f95e52 AM |
326 | } |
327 | ||
206dc69b JA |
328 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) |
329 | { | |
b31dc66a | 330 | if (rw == READ || rw == WRITE_SYNC) |
206dc69b JA |
331 | return task->pid; |
332 | ||
333 | return CFQ_KEY_ASYNC; | |
334 | } | |
335 | ||
1da177e4 LT |
336 | /* |
337 | * Lifted from AS - choose which of crq1 and crq2 that is best served now. | |
338 | * We choose the request that is closest to the head right now. Distance | |
e8a99053 | 339 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 LT |
340 | */ |
341 | static struct cfq_rq * | |
342 | cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) | |
343 | { | |
344 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 345 | unsigned long back_max; |
e8a99053 AM |
346 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
347 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
348 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 LT |
349 | |
350 | if (crq1 == NULL || crq1 == crq2) | |
351 | return crq2; | |
352 | if (crq2 == NULL) | |
353 | return crq1; | |
9c2c38a1 | 354 | |
9c2c38a1 JA |
355 | if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) |
356 | return crq1; | |
357 | else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) | |
22e2c507 | 358 | return crq2; |
1da177e4 LT |
359 | |
360 | s1 = crq1->request->sector; | |
361 | s2 = crq2->request->sector; | |
362 | ||
363 | last = cfqd->last_sector; | |
364 | ||
1da177e4 LT |
365 | /* |
366 | * by definition, 1KiB is 2 sectors | |
367 | */ | |
368 | back_max = cfqd->cfq_back_max * 2; | |
369 | ||
370 | /* | |
371 | * Strict one way elevator _except_ in the case where we allow | |
372 | * short backward seeks which are biased as twice the cost of a | |
373 | * similar forward seek. | |
374 | */ | |
375 | if (s1 >= last) | |
376 | d1 = s1 - last; | |
377 | else if (s1 + back_max >= last) | |
378 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
379 | else | |
e8a99053 | 380 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
381 | |
382 | if (s2 >= last) | |
383 | d2 = s2 - last; | |
384 | else if (s2 + back_max >= last) | |
385 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
386 | else | |
e8a99053 | 387 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
388 | |
389 | /* Found required data */ | |
e8a99053 AM |
390 | |
391 | /* | |
392 | * By doing switch() on the bit mask "wrap" we avoid having to | |
393 | * check two variables for all permutations: --> faster! | |
394 | */ | |
395 | switch (wrap) { | |
396 | case 0: /* common case for CFQ: crq1 and crq2 not wrapped */ | |
397 | if (d1 < d2) | |
1da177e4 | 398 | return crq1; |
e8a99053 | 399 | else if (d2 < d1) |
1da177e4 | 400 | return crq2; |
e8a99053 AM |
401 | else { |
402 | if (s1 >= s2) | |
403 | return crq1; | |
404 | else | |
405 | return crq2; | |
406 | } | |
1da177e4 | 407 | |
e8a99053 | 408 | case CFQ_RQ2_WRAP: |
1da177e4 | 409 | return crq1; |
e8a99053 | 410 | case CFQ_RQ1_WRAP: |
1da177e4 | 411 | return crq2; |
e8a99053 AM |
412 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both crqs wrapped */ |
413 | default: | |
414 | /* | |
415 | * Since both rqs are wrapped, | |
416 | * start with the one that's further behind head | |
417 | * (--> only *one* back seek required), | |
418 | * since back seek takes more time than forward. | |
419 | */ | |
420 | if (s1 <= s2) | |
1da177e4 LT |
421 | return crq1; |
422 | else | |
423 | return crq2; | |
424 | } | |
425 | } | |
426 | ||
427 | /* | |
428 | * would be nice to take fifo expire time into account as well | |
429 | */ | |
430 | static struct cfq_rq * | |
431 | cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
432 | struct cfq_rq *last) | |
433 | { | |
434 | struct cfq_rq *crq_next = NULL, *crq_prev = NULL; | |
435 | struct rb_node *rbnext, *rbprev; | |
436 | ||
b4878f24 | 437 | if (!(rbnext = rb_next(&last->rb_node))) { |
1da177e4 | 438 | rbnext = rb_first(&cfqq->sort_list); |
22e2c507 JA |
439 | if (rbnext == &last->rb_node) |
440 | rbnext = NULL; | |
441 | } | |
1da177e4 LT |
442 | |
443 | rbprev = rb_prev(&last->rb_node); | |
444 | ||
445 | if (rbprev) | |
446 | crq_prev = rb_entry_crq(rbprev); | |
447 | if (rbnext) | |
448 | crq_next = rb_entry_crq(rbnext); | |
449 | ||
450 | return cfq_choose_req(cfqd, crq_next, crq_prev); | |
451 | } | |
452 | ||
453 | static void cfq_update_next_crq(struct cfq_rq *crq) | |
454 | { | |
455 | struct cfq_queue *cfqq = crq->cfq_queue; | |
456 | ||
457 | if (cfqq->next_crq == crq) | |
458 | cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); | |
459 | } | |
460 | ||
22e2c507 | 461 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
1da177e4 | 462 | { |
22e2c507 JA |
463 | struct cfq_data *cfqd = cfqq->cfqd; |
464 | struct list_head *list, *entry; | |
1da177e4 | 465 | |
3b18152c | 466 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 467 | |
22e2c507 | 468 | list_del(&cfqq->cfq_list); |
1da177e4 | 469 | |
22e2c507 JA |
470 | if (cfq_class_rt(cfqq)) |
471 | list = &cfqd->cur_rr; | |
472 | else if (cfq_class_idle(cfqq)) | |
473 | list = &cfqd->idle_rr; | |
474 | else { | |
475 | /* | |
476 | * if cfqq has requests in flight, don't allow it to be | |
477 | * found in cfq_set_active_queue before it has finished them. | |
478 | * this is done to increase fairness between a process that | |
479 | * has lots of io pending vs one that only generates one | |
480 | * sporadically or synchronously | |
481 | */ | |
3b18152c | 482 | if (cfq_cfqq_dispatched(cfqq)) |
22e2c507 JA |
483 | list = &cfqd->busy_rr; |
484 | else | |
485 | list = &cfqd->rr_list[cfqq->ioprio]; | |
1da177e4 LT |
486 | } |
487 | ||
22e2c507 JA |
488 | /* |
489 | * if queue was preempted, just add to front to be fair. busy_rr | |
b52a8348 | 490 | * isn't sorted, but insert at the back for fairness. |
22e2c507 JA |
491 | */ |
492 | if (preempted || list == &cfqd->busy_rr) { | |
b52a8348 JA |
493 | if (preempted) |
494 | list = list->prev; | |
495 | ||
496 | list_add_tail(&cfqq->cfq_list, list); | |
1da177e4 | 497 | return; |
22e2c507 | 498 | } |
1da177e4 LT |
499 | |
500 | /* | |
22e2c507 | 501 | * sort by when queue was last serviced |
1da177e4 | 502 | */ |
22e2c507 JA |
503 | entry = list; |
504 | while ((entry = entry->prev) != list) { | |
1da177e4 LT |
505 | struct cfq_queue *__cfqq = list_entry_cfqq(entry); |
506 | ||
22e2c507 JA |
507 | if (!__cfqq->service_last) |
508 | break; | |
509 | if (time_before(__cfqq->service_last, cfqq->service_last)) | |
1da177e4 | 510 | break; |
1da177e4 LT |
511 | } |
512 | ||
513 | list_add(&cfqq->cfq_list, entry); | |
514 | } | |
515 | ||
516 | /* | |
517 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 518 | * the pending list according to last request service |
1da177e4 LT |
519 | */ |
520 | static inline void | |
b4878f24 | 521 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 522 | { |
3b18152c JA |
523 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
524 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
525 | cfqd->busy_queues++; |
526 | ||
b4878f24 | 527 | cfq_resort_rr_list(cfqq, 0); |
1da177e4 LT |
528 | } |
529 | ||
530 | static inline void | |
531 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
532 | { | |
3b18152c JA |
533 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
534 | cfq_clear_cfqq_on_rr(cfqq); | |
22e2c507 | 535 | list_move(&cfqq->cfq_list, &cfqd->empty_list); |
1da177e4 LT |
536 | |
537 | BUG_ON(!cfqd->busy_queues); | |
538 | cfqd->busy_queues--; | |
539 | } | |
540 | ||
541 | /* | |
542 | * rb tree support functions | |
543 | */ | |
544 | static inline void cfq_del_crq_rb(struct cfq_rq *crq) | |
545 | { | |
546 | struct cfq_queue *cfqq = crq->cfq_queue; | |
b4878f24 JA |
547 | struct cfq_data *cfqd = cfqq->cfqd; |
548 | const int sync = cfq_crq_is_sync(crq); | |
1da177e4 | 549 | |
b4878f24 JA |
550 | BUG_ON(!cfqq->queued[sync]); |
551 | cfqq->queued[sync]--; | |
1da177e4 | 552 | |
b4878f24 | 553 | cfq_update_next_crq(crq); |
1da177e4 | 554 | |
b4878f24 | 555 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
1da177e4 | 556 | |
dd67d051 | 557 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 558 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
559 | } |
560 | ||
561 | static 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 | ||
584 | static 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); | |
3b18152c | 592 | cfqq->queued[cfq_crq_is_sync(crq)]++; |
1da177e4 LT |
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) | |
b4878f24 | 599 | cfq_dispatch_insert(cfqd->queue, __alias); |
1da177e4 LT |
600 | |
601 | rb_insert_color(&crq->rb_node, &cfqq->sort_list); | |
602 | ||
3b18152c | 603 | if (!cfq_cfqq_on_rr(cfqq)) |
b4878f24 | 604 | cfq_add_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
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 | ||
612 | static inline void | |
613 | cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
614 | { | |
b4878f24 JA |
615 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
616 | cfqq->queued[cfq_crq_is_sync(crq)]--; | |
1da177e4 LT |
617 | |
618 | cfq_add_crq_rb(crq); | |
619 | } | |
620 | ||
206dc69b JA |
621 | static struct request * |
622 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 623 | { |
206dc69b JA |
624 | struct task_struct *tsk = current; |
625 | pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio)); | |
626 | struct cfq_queue *cfqq; | |
1da177e4 | 627 | struct rb_node *n; |
206dc69b | 628 | sector_t sector; |
1da177e4 | 629 | |
206dc69b | 630 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); |
1da177e4 LT |
631 | if (!cfqq) |
632 | goto out; | |
633 | ||
206dc69b | 634 | sector = bio->bi_sector + bio_sectors(bio); |
1da177e4 LT |
635 | n = cfqq->sort_list.rb_node; |
636 | while (n) { | |
637 | struct cfq_rq *crq = rb_entry_crq(n); | |
638 | ||
639 | if (sector < crq->rb_key) | |
640 | n = n->rb_left; | |
641 | else if (sector > crq->rb_key) | |
642 | n = n->rb_right; | |
643 | else | |
644 | return crq->request; | |
645 | } | |
646 | ||
647 | out: | |
648 | return NULL; | |
649 | } | |
650 | ||
b4878f24 | 651 | static void cfq_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 652 | { |
22e2c507 | 653 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 654 | |
b4878f24 | 655 | cfqd->rq_in_driver++; |
25776e35 JA |
656 | |
657 | /* | |
658 | * If the depth is larger 1, it really could be queueing. But lets | |
659 | * make the mark a little higher - idling could still be good for | |
660 | * low queueing, and a low queueing number could also just indicate | |
661 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
662 | */ | |
663 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
664 | cfqd->hw_tag = 1; | |
1da177e4 LT |
665 | } |
666 | ||
b4878f24 | 667 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 668 | { |
b4878f24 JA |
669 | struct cfq_data *cfqd = q->elevator->elevator_data; |
670 | ||
671 | WARN_ON(!cfqd->rq_in_driver); | |
672 | cfqd->rq_in_driver--; | |
1da177e4 LT |
673 | } |
674 | ||
b4878f24 | 675 | static void cfq_remove_request(struct request *rq) |
1da177e4 LT |
676 | { |
677 | struct cfq_rq *crq = RQ_DATA(rq); | |
678 | ||
b4878f24 JA |
679 | list_del_init(&rq->queuelist); |
680 | cfq_del_crq_rb(crq); | |
98b11471 | 681 | cfq_del_crq_hash(crq); |
1da177e4 LT |
682 | } |
683 | ||
684 | static int | |
685 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
686 | { | |
687 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
688 | struct request *__rq; | |
689 | int ret; | |
690 | ||
1da177e4 | 691 | __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); |
22e2c507 JA |
692 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
693 | ret = ELEVATOR_BACK_MERGE; | |
694 | goto out; | |
1da177e4 LT |
695 | } |
696 | ||
206dc69b | 697 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 JA |
698 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
699 | ret = ELEVATOR_FRONT_MERGE; | |
700 | goto out; | |
1da177e4 LT |
701 | } |
702 | ||
703 | return ELEVATOR_NO_MERGE; | |
704 | out: | |
1da177e4 LT |
705 | *req = __rq; |
706 | return ret; | |
707 | } | |
708 | ||
709 | static void cfq_merged_request(request_queue_t *q, struct request *req) | |
710 | { | |
711 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
712 | struct cfq_rq *crq = RQ_DATA(req); | |
713 | ||
714 | cfq_del_crq_hash(crq); | |
715 | cfq_add_crq_hash(cfqd, crq); | |
716 | ||
b4878f24 | 717 | if (rq_rb_key(req) != crq->rb_key) { |
1da177e4 LT |
718 | struct cfq_queue *cfqq = crq->cfq_queue; |
719 | ||
720 | cfq_update_next_crq(crq); | |
721 | cfq_reposition_crq_rb(cfqq, crq); | |
722 | } | |
1da177e4 LT |
723 | } |
724 | ||
725 | static void | |
726 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
727 | struct request *next) | |
728 | { | |
1da177e4 LT |
729 | cfq_merged_request(q, rq); |
730 | ||
22e2c507 JA |
731 | /* |
732 | * reposition in fifo if next is older than rq | |
733 | */ | |
734 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
735 | time_before(next->start_time, rq->start_time)) | |
736 | list_move(&rq->queuelist, &next->queuelist); | |
737 | ||
b4878f24 | 738 | cfq_remove_request(next); |
22e2c507 JA |
739 | } |
740 | ||
741 | static inline void | |
742 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
743 | { | |
744 | if (cfqq) { | |
745 | /* | |
746 | * stop potential idle class queues waiting service | |
747 | */ | |
748 | del_timer(&cfqd->idle_class_timer); | |
749 | ||
750 | cfqq->slice_start = jiffies; | |
751 | cfqq->slice_end = 0; | |
752 | cfqq->slice_left = 0; | |
3b18152c JA |
753 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
754 | cfq_clear_cfqq_fifo_expire(cfqq); | |
22e2c507 JA |
755 | } |
756 | ||
757 | cfqd->active_queue = cfqq; | |
758 | } | |
759 | ||
7b14e3b5 JA |
760 | /* |
761 | * current cfqq expired its slice (or was too idle), select new one | |
762 | */ | |
763 | static void | |
764 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
765 | int preempted) | |
766 | { | |
767 | unsigned long now = jiffies; | |
768 | ||
769 | if (cfq_cfqq_wait_request(cfqq)) | |
770 | del_timer(&cfqd->idle_slice_timer); | |
771 | ||
772 | if (!preempted && !cfq_cfqq_dispatched(cfqq)) { | |
773 | cfqq->service_last = now; | |
774 | cfq_schedule_dispatch(cfqd); | |
775 | } | |
776 | ||
777 | cfq_clear_cfqq_must_dispatch(cfqq); | |
778 | cfq_clear_cfqq_wait_request(cfqq); | |
779 | ||
780 | /* | |
781 | * store what was left of this slice, if the queue idled out | |
782 | * or was preempted | |
783 | */ | |
784 | if (time_after(cfqq->slice_end, now)) | |
785 | cfqq->slice_left = cfqq->slice_end - now; | |
786 | else | |
787 | cfqq->slice_left = 0; | |
788 | ||
789 | if (cfq_cfqq_on_rr(cfqq)) | |
790 | cfq_resort_rr_list(cfqq, preempted); | |
791 | ||
792 | if (cfqq == cfqd->active_queue) | |
793 | cfqd->active_queue = NULL; | |
794 | ||
795 | if (cfqd->active_cic) { | |
796 | put_io_context(cfqd->active_cic->ioc); | |
797 | cfqd->active_cic = NULL; | |
798 | } | |
799 | ||
800 | cfqd->dispatch_slice = 0; | |
801 | } | |
802 | ||
803 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
804 | { | |
805 | struct cfq_queue *cfqq = cfqd->active_queue; | |
806 | ||
807 | if (cfqq) | |
808 | __cfq_slice_expired(cfqd, cfqq, preempted); | |
809 | } | |
810 | ||
22e2c507 JA |
811 | /* |
812 | * 0 | |
813 | * 0,1 | |
814 | * 0,1,2 | |
815 | * 0,1,2,3 | |
816 | * 0,1,2,3,4 | |
817 | * 0,1,2,3,4,5 | |
818 | * 0,1,2,3,4,5,6 | |
819 | * 0,1,2,3,4,5,6,7 | |
820 | */ | |
821 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
822 | { | |
823 | int prio, wrap; | |
824 | ||
825 | prio = -1; | |
826 | wrap = 0; | |
827 | do { | |
828 | int p; | |
829 | ||
830 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
831 | if (!list_empty(&cfqd->rr_list[p])) { | |
832 | prio = p; | |
833 | break; | |
834 | } | |
835 | } | |
836 | ||
837 | if (prio != -1) | |
838 | break; | |
839 | cfqd->cur_prio = 0; | |
840 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
841 | cfqd->cur_end_prio = 0; | |
842 | if (wrap) | |
843 | break; | |
844 | wrap = 1; | |
1da177e4 | 845 | } |
22e2c507 JA |
846 | } while (1); |
847 | ||
848 | if (unlikely(prio == -1)) | |
849 | return -1; | |
850 | ||
851 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
852 | ||
853 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
854 | ||
855 | cfqd->cur_prio = prio + 1; | |
856 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
857 | cfqd->cur_end_prio = cfqd->cur_prio; | |
858 | cfqd->cur_prio = 0; | |
859 | } | |
860 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
861 | cfqd->cur_prio = 0; | |
862 | cfqd->cur_end_prio = 0; | |
1da177e4 LT |
863 | } |
864 | ||
22e2c507 JA |
865 | return prio; |
866 | } | |
867 | ||
3b18152c | 868 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
22e2c507 | 869 | { |
7b14e3b5 | 870 | struct cfq_queue *cfqq = NULL; |
22e2c507 JA |
871 | |
872 | /* | |
873 | * if current list is non-empty, grab first entry. if it is empty, | |
874 | * get next prio level and grab first entry then if any are spliced | |
875 | */ | |
876 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) | |
877 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
878 | ||
e0de0206 JA |
879 | /* |
880 | * If no new queues are available, check if the busy list has some | |
881 | * before falling back to idle io. | |
882 | */ | |
883 | if (!cfqq && !list_empty(&cfqd->busy_rr)) | |
884 | cfqq = list_entry_cfqq(cfqd->busy_rr.next); | |
885 | ||
22e2c507 JA |
886 | /* |
887 | * if we have idle queues and no rt or be queues had pending | |
888 | * requests, either allow immediate service if the grace period | |
889 | * has passed or arm the idle grace timer | |
890 | */ | |
891 | if (!cfqq && !list_empty(&cfqd->idle_rr)) { | |
892 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
893 | ||
894 | if (time_after_eq(jiffies, end)) | |
895 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
896 | else | |
897 | mod_timer(&cfqd->idle_class_timer, end); | |
898 | } | |
899 | ||
900 | __cfq_set_active_queue(cfqd, cfqq); | |
3b18152c | 901 | return cfqq; |
22e2c507 JA |
902 | } |
903 | ||
caaa5f9f JA |
904 | #define CIC_SEEKY(cic) ((cic)->seek_mean > (128 * 1024)) |
905 | ||
22e2c507 JA |
906 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
907 | ||
908 | { | |
206dc69b | 909 | struct cfq_io_context *cic; |
7b14e3b5 JA |
910 | unsigned long sl; |
911 | ||
dd67d051 | 912 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
22e2c507 JA |
913 | WARN_ON(cfqq != cfqd->active_queue); |
914 | ||
915 | /* | |
916 | * idle is disabled, either manually or by past process history | |
917 | */ | |
918 | if (!cfqd->cfq_slice_idle) | |
919 | return 0; | |
3b18152c | 920 | if (!cfq_cfqq_idle_window(cfqq)) |
22e2c507 JA |
921 | return 0; |
922 | /* | |
923 | * task has exited, don't wait | |
924 | */ | |
206dc69b JA |
925 | cic = cfqd->active_cic; |
926 | if (!cic || !cic->ioc->task) | |
22e2c507 JA |
927 | return 0; |
928 | ||
3b18152c JA |
929 | cfq_mark_cfqq_must_dispatch(cfqq); |
930 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 931 | |
7b14e3b5 | 932 | sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); |
206dc69b JA |
933 | |
934 | /* | |
935 | * we don't want to idle for seeks, but we do want to allow | |
936 | * fair distribution of slice time for a process doing back-to-back | |
937 | * seeks. so allow a little bit of time for him to submit a new rq | |
938 | */ | |
caaa5f9f | 939 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
206dc69b JA |
940 | sl = 2; |
941 | ||
7b14e3b5 | 942 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
22e2c507 | 943 | return 1; |
1da177e4 LT |
944 | } |
945 | ||
b4878f24 | 946 | static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) |
1da177e4 LT |
947 | { |
948 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
949 | struct cfq_queue *cfqq = crq->cfq_queue; | |
fd61af03 | 950 | struct request *rq; |
22e2c507 JA |
951 | |
952 | cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); | |
b4878f24 | 953 | cfq_remove_request(crq->request); |
3b18152c | 954 | cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; |
b4878f24 | 955 | elv_dispatch_sort(q, crq->request); |
fd61af03 JA |
956 | |
957 | rq = list_entry(q->queue_head.prev, struct request, queuelist); | |
958 | cfqd->last_sector = rq->sector + rq->nr_sectors; | |
1da177e4 LT |
959 | } |
960 | ||
961 | /* | |
962 | * return expired entry, or NULL to just start from scratch in rbtree | |
963 | */ | |
964 | static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) | |
965 | { | |
966 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 967 | struct request *rq; |
1da177e4 LT |
968 | struct cfq_rq *crq; |
969 | ||
3b18152c | 970 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 LT |
971 | return NULL; |
972 | ||
22e2c507 | 973 | if (!list_empty(&cfqq->fifo)) { |
3b18152c | 974 | int fifo = cfq_cfqq_class_sync(cfqq); |
1da177e4 | 975 | |
22e2c507 JA |
976 | crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); |
977 | rq = crq->request; | |
978 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
3b18152c | 979 | cfq_mark_cfqq_fifo_expire(cfqq); |
22e2c507 JA |
980 | return crq; |
981 | } | |
1da177e4 LT |
982 | } |
983 | ||
984 | return NULL; | |
985 | } | |
986 | ||
987 | /* | |
3b18152c JA |
988 | * Scale schedule slice based on io priority. Use the sync time slice only |
989 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
990 | * io only, should not get full sync slice length. | |
1da177e4 | 991 | */ |
22e2c507 JA |
992 | static inline int |
993 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
994 | { | |
995 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
996 | ||
997 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
998 | ||
999 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
1000 | } | |
1001 | ||
1da177e4 | 1002 | static inline void |
22e2c507 | 1003 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1004 | { |
22e2c507 JA |
1005 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
1006 | } | |
1da177e4 | 1007 | |
22e2c507 JA |
1008 | static inline int |
1009 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1010 | { | |
1011 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1012 | |
22e2c507 | 1013 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1014 | |
22e2c507 | 1015 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1016 | } |
1017 | ||
22e2c507 JA |
1018 | /* |
1019 | * get next queue for service | |
1020 | */ | |
1b5ed5e1 | 1021 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1022 | { |
22e2c507 | 1023 | unsigned long now = jiffies; |
1da177e4 | 1024 | struct cfq_queue *cfqq; |
1da177e4 | 1025 | |
22e2c507 JA |
1026 | cfqq = cfqd->active_queue; |
1027 | if (!cfqq) | |
1028 | goto new_queue; | |
1da177e4 | 1029 | |
22e2c507 JA |
1030 | /* |
1031 | * slice has expired | |
1032 | */ | |
3b18152c JA |
1033 | if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) |
1034 | goto expire; | |
1da177e4 | 1035 | |
22e2c507 JA |
1036 | /* |
1037 | * if queue has requests, dispatch one. if not, check if | |
1038 | * enough slice is left to wait for one | |
1039 | */ | |
dd67d051 | 1040 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1041 | goto keep_queue; |
caaa5f9f JA |
1042 | else if (cfq_cfqq_dispatched(cfqq)) { |
1043 | cfqq = NULL; | |
1044 | goto keep_queue; | |
1045 | } else if (cfq_cfqq_class_sync(cfqq)) { | |
22e2c507 JA |
1046 | if (cfq_arm_slice_timer(cfqd, cfqq)) |
1047 | return NULL; | |
1048 | } | |
1049 | ||
3b18152c | 1050 | expire: |
22e2c507 | 1051 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
1052 | new_queue: |
1053 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 1054 | keep_queue: |
3b18152c | 1055 | return cfqq; |
22e2c507 JA |
1056 | } |
1057 | ||
1058 | static int | |
1059 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1060 | int max_dispatch) | |
1061 | { | |
1062 | int dispatched = 0; | |
1063 | ||
dd67d051 | 1064 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
22e2c507 JA |
1065 | |
1066 | do { | |
1067 | struct cfq_rq *crq; | |
1da177e4 LT |
1068 | |
1069 | /* | |
22e2c507 | 1070 | * follow expired path, else get first next available |
1da177e4 | 1071 | */ |
22e2c507 JA |
1072 | if ((crq = cfq_check_fifo(cfqq)) == NULL) |
1073 | crq = cfqq->next_crq; | |
1074 | ||
1075 | /* | |
1076 | * finally, insert request into driver dispatch list | |
1077 | */ | |
b4878f24 | 1078 | cfq_dispatch_insert(cfqd->queue, crq); |
1da177e4 | 1079 | |
22e2c507 JA |
1080 | cfqd->dispatch_slice++; |
1081 | dispatched++; | |
1da177e4 | 1082 | |
22e2c507 JA |
1083 | if (!cfqd->active_cic) { |
1084 | atomic_inc(&crq->io_context->ioc->refcount); | |
1085 | cfqd->active_cic = crq->io_context; | |
1086 | } | |
1da177e4 | 1087 | |
dd67d051 | 1088 | if (RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 JA |
1089 | break; |
1090 | ||
1091 | } while (dispatched < max_dispatch); | |
1092 | ||
1093 | /* | |
caaa5f9f | 1094 | * if slice end isn't set yet, set it. |
22e2c507 JA |
1095 | */ |
1096 | if (!cfqq->slice_end) | |
1097 | cfq_set_prio_slice(cfqd, cfqq); | |
1098 | ||
1099 | /* | |
1100 | * expire an async queue immediately if it has used up its slice. idle | |
1101 | * queue always expire after 1 dispatch round. | |
1102 | */ | |
1103 | if ((!cfq_cfqq_sync(cfqq) && | |
1104 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
caaa5f9f JA |
1105 | cfq_class_idle(cfqq) || |
1106 | !cfq_cfqq_idle_window(cfqq)) | |
22e2c507 JA |
1107 | cfq_slice_expired(cfqd, 0); |
1108 | ||
1109 | return dispatched; | |
1110 | } | |
1111 | ||
1b5ed5e1 TH |
1112 | static int |
1113 | cfq_forced_dispatch_cfqqs(struct list_head *list) | |
1114 | { | |
1b5ed5e1 TH |
1115 | struct cfq_queue *cfqq, *next; |
1116 | struct cfq_rq *crq; | |
caaa5f9f | 1117 | int dispatched; |
1b5ed5e1 | 1118 | |
caaa5f9f | 1119 | dispatched = 0; |
1b5ed5e1 TH |
1120 | list_for_each_entry_safe(cfqq, next, list, cfq_list) { |
1121 | while ((crq = cfqq->next_crq)) { | |
1122 | cfq_dispatch_insert(cfqq->cfqd->queue, crq); | |
1123 | dispatched++; | |
1124 | } | |
1125 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1126 | } | |
caaa5f9f | 1127 | |
1b5ed5e1 TH |
1128 | return dispatched; |
1129 | } | |
1130 | ||
1131 | static int | |
1132 | cfq_forced_dispatch(struct cfq_data *cfqd) | |
1133 | { | |
1134 | int i, dispatched = 0; | |
1135 | ||
1136 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
1137 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]); | |
1138 | ||
1139 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr); | |
1140 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); | |
1141 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
1142 | ||
1143 | cfq_slice_expired(cfqd, 0); | |
1144 | ||
1145 | BUG_ON(cfqd->busy_queues); | |
1146 | ||
1147 | return dispatched; | |
1148 | } | |
1149 | ||
22e2c507 | 1150 | static int |
b4878f24 | 1151 | cfq_dispatch_requests(request_queue_t *q, int force) |
22e2c507 JA |
1152 | { |
1153 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
caaa5f9f JA |
1154 | struct cfq_queue *cfqq, *prev_cfqq; |
1155 | int dispatched; | |
22e2c507 JA |
1156 | |
1157 | if (!cfqd->busy_queues) | |
1158 | return 0; | |
1159 | ||
1b5ed5e1 TH |
1160 | if (unlikely(force)) |
1161 | return cfq_forced_dispatch(cfqd); | |
1162 | ||
caaa5f9f JA |
1163 | dispatched = 0; |
1164 | prev_cfqq = NULL; | |
1165 | while ((cfqq = cfq_select_queue(cfqd)) != NULL) { | |
b4878f24 JA |
1166 | int max_dispatch; |
1167 | ||
caaa5f9f JA |
1168 | /* |
1169 | * Don't repeat dispatch from the previous queue. | |
1170 | */ | |
1171 | if (prev_cfqq == cfqq) | |
1172 | break; | |
1173 | ||
3b18152c JA |
1174 | cfq_clear_cfqq_must_dispatch(cfqq); |
1175 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1176 | del_timer(&cfqd->idle_slice_timer); |
1177 | ||
1b5ed5e1 TH |
1178 | max_dispatch = cfqd->cfq_quantum; |
1179 | if (cfq_class_idle(cfqq)) | |
1180 | max_dispatch = 1; | |
1da177e4 | 1181 | |
caaa5f9f JA |
1182 | dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1183 | ||
1184 | /* | |
1185 | * If the dispatch cfqq has idling enabled and is still | |
1186 | * the active queue, break out. | |
1187 | */ | |
1188 | if (cfq_cfqq_idle_window(cfqq) && cfqd->active_queue) | |
1189 | break; | |
1190 | ||
1191 | prev_cfqq = cfqq; | |
1da177e4 LT |
1192 | } |
1193 | ||
caaa5f9f | 1194 | return dispatched; |
1da177e4 LT |
1195 | } |
1196 | ||
1da177e4 LT |
1197 | /* |
1198 | * task holds one reference to the queue, dropped when task exits. each crq | |
1199 | * in-flight on this queue also holds a reference, dropped when crq is freed. | |
1200 | * | |
1201 | * queue lock must be held here. | |
1202 | */ | |
1203 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1204 | { | |
22e2c507 JA |
1205 | struct cfq_data *cfqd = cfqq->cfqd; |
1206 | ||
1207 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1208 | |
1209 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1210 | return; | |
1211 | ||
1212 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1213 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1214 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1215 | |
7b14e3b5 | 1216 | if (unlikely(cfqd->active_queue == cfqq)) |
3b18152c | 1217 | __cfq_slice_expired(cfqd, cfqq, 0); |
22e2c507 | 1218 | |
1da177e4 LT |
1219 | /* |
1220 | * it's on the empty list and still hashed | |
1221 | */ | |
1222 | list_del(&cfqq->cfq_list); | |
1223 | hlist_del(&cfqq->cfq_hash); | |
1224 | kmem_cache_free(cfq_pool, cfqq); | |
1225 | } | |
1226 | ||
1227 | static inline struct cfq_queue * | |
3b18152c JA |
1228 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, |
1229 | const int hashval) | |
1da177e4 LT |
1230 | { |
1231 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
206dc69b JA |
1232 | struct hlist_node *entry; |
1233 | struct cfq_queue *__cfqq; | |
1da177e4 | 1234 | |
206dc69b | 1235 | hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) { |
b0a6916b | 1236 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); |
1da177e4 | 1237 | |
206dc69b | 1238 | if (__cfqq->key == key && (__p == prio || !prio)) |
1da177e4 LT |
1239 | return __cfqq; |
1240 | } | |
1241 | ||
1242 | return NULL; | |
1243 | } | |
1244 | ||
1245 | static struct cfq_queue * | |
3b18152c | 1246 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) |
1da177e4 | 1247 | { |
3b18152c | 1248 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); |
1da177e4 LT |
1249 | } |
1250 | ||
e2d74ac0 | 1251 | static void cfq_free_io_context(struct io_context *ioc) |
1da177e4 | 1252 | { |
22e2c507 | 1253 | struct cfq_io_context *__cic; |
e2d74ac0 JA |
1254 | struct rb_node *n; |
1255 | int freed = 0; | |
1da177e4 | 1256 | |
e2d74ac0 JA |
1257 | while ((n = rb_first(&ioc->cic_root)) != NULL) { |
1258 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1259 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
22e2c507 | 1260 | kmem_cache_free(cfq_ioc_pool, __cic); |
334e94de | 1261 | freed++; |
1da177e4 LT |
1262 | } |
1263 | ||
334e94de AV |
1264 | if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone) |
1265 | complete(ioc_gone); | |
1da177e4 LT |
1266 | } |
1267 | ||
e17a9489 AV |
1268 | static void cfq_trim(struct io_context *ioc) |
1269 | { | |
1270 | ioc->set_ioprio = NULL; | |
e2d74ac0 | 1271 | cfq_free_io_context(ioc); |
e17a9489 AV |
1272 | } |
1273 | ||
22e2c507 JA |
1274 | /* |
1275 | * Called with interrupts disabled | |
1276 | */ | |
1277 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1da177e4 | 1278 | { |
478a82b0 | 1279 | struct cfq_data *cfqd = cic->key; |
d9ff4187 AV |
1280 | request_queue_t *q; |
1281 | ||
1282 | if (!cfqd) | |
1283 | return; | |
1284 | ||
1285 | q = cfqd->queue; | |
22e2c507 JA |
1286 | |
1287 | WARN_ON(!irqs_disabled()); | |
1288 | ||
1289 | spin_lock(q->queue_lock); | |
1290 | ||
12a05732 AV |
1291 | if (cic->cfqq[ASYNC]) { |
1292 | if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue)) | |
1293 | __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0); | |
1294 | cfq_put_queue(cic->cfqq[ASYNC]); | |
1295 | cic->cfqq[ASYNC] = NULL; | |
1296 | } | |
1297 | ||
1298 | if (cic->cfqq[SYNC]) { | |
1299 | if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue)) | |
1300 | __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0); | |
1301 | cfq_put_queue(cic->cfqq[SYNC]); | |
1302 | cic->cfqq[SYNC] = NULL; | |
1303 | } | |
22e2c507 | 1304 | |
478a82b0 | 1305 | cic->key = NULL; |
d9ff4187 | 1306 | list_del_init(&cic->queue_list); |
22e2c507 | 1307 | spin_unlock(q->queue_lock); |
1da177e4 LT |
1308 | } |
1309 | ||
e2d74ac0 | 1310 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1311 | { |
22e2c507 | 1312 | struct cfq_io_context *__cic; |
1da177e4 | 1313 | unsigned long flags; |
e2d74ac0 | 1314 | struct rb_node *n; |
22e2c507 | 1315 | |
1da177e4 LT |
1316 | /* |
1317 | * put the reference this task is holding to the various queues | |
1318 | */ | |
3793c65c | 1319 | spin_lock_irqsave(&cfq_exit_lock, flags); |
e2d74ac0 JA |
1320 | |
1321 | n = rb_first(&ioc->cic_root); | |
1322 | while (n != NULL) { | |
1323 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1324 | ||
22e2c507 | 1325 | cfq_exit_single_io_context(__cic); |
e2d74ac0 | 1326 | n = rb_next(n); |
1da177e4 LT |
1327 | } |
1328 | ||
3793c65c | 1329 | spin_unlock_irqrestore(&cfq_exit_lock, flags); |
1da177e4 LT |
1330 | } |
1331 | ||
22e2c507 | 1332 | static struct cfq_io_context * |
8267e268 | 1333 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1334 | { |
22e2c507 | 1335 | struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); |
1da177e4 LT |
1336 | |
1337 | if (cic) { | |
553698f9 | 1338 | memset(cic, 0, sizeof(*cic)); |
22e2c507 | 1339 | cic->last_end_request = jiffies; |
553698f9 | 1340 | INIT_LIST_HEAD(&cic->queue_list); |
22e2c507 JA |
1341 | cic->dtor = cfq_free_io_context; |
1342 | cic->exit = cfq_exit_io_context; | |
334e94de | 1343 | atomic_inc(&ioc_count); |
1da177e4 LT |
1344 | } |
1345 | ||
1346 | return cic; | |
1347 | } | |
1348 | ||
22e2c507 JA |
1349 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1350 | { | |
1351 | struct task_struct *tsk = current; | |
1352 | int ioprio_class; | |
1353 | ||
3b18152c | 1354 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1355 | return; |
1356 | ||
1357 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1358 | switch (ioprio_class) { | |
1359 | default: | |
1360 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1361 | case IOPRIO_CLASS_NONE: | |
1362 | /* | |
1363 | * no prio set, place us in the middle of the BE classes | |
1364 | */ | |
1365 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1366 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1367 | break; | |
1368 | case IOPRIO_CLASS_RT: | |
1369 | cfqq->ioprio = task_ioprio(tsk); | |
1370 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1371 | break; | |
1372 | case IOPRIO_CLASS_BE: | |
1373 | cfqq->ioprio = task_ioprio(tsk); | |
1374 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1375 | break; | |
1376 | case IOPRIO_CLASS_IDLE: | |
1377 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1378 | cfqq->ioprio = 7; | |
3b18152c | 1379 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1380 | break; |
1381 | } | |
1382 | ||
1383 | /* | |
1384 | * keep track of original prio settings in case we have to temporarily | |
1385 | * elevate the priority of this queue | |
1386 | */ | |
1387 | cfqq->org_ioprio = cfqq->ioprio; | |
1388 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1389 | ||
3b18152c | 1390 | if (cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1391 | cfq_resort_rr_list(cfqq, 0); |
1392 | ||
3b18152c | 1393 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1394 | } |
1395 | ||
478a82b0 | 1396 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1397 | { |
478a82b0 AV |
1398 | struct cfq_data *cfqd = cic->key; |
1399 | struct cfq_queue *cfqq; | |
35e6077c | 1400 | |
caaa5f9f JA |
1401 | if (unlikely(!cfqd)) |
1402 | return; | |
1403 | ||
1404 | spin_lock(cfqd->queue->queue_lock); | |
1405 | ||
1406 | cfqq = cic->cfqq[ASYNC]; | |
1407 | if (cfqq) { | |
1408 | struct cfq_queue *new_cfqq; | |
1409 | new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC, cic->ioc->task, | |
1410 | GFP_ATOMIC); | |
1411 | if (new_cfqq) { | |
1412 | cic->cfqq[ASYNC] = new_cfqq; | |
1413 | cfq_put_queue(cfqq); | |
1414 | } | |
22e2c507 | 1415 | } |
caaa5f9f JA |
1416 | |
1417 | cfqq = cic->cfqq[SYNC]; | |
1418 | if (cfqq) | |
1419 | cfq_mark_cfqq_prio_changed(cfqq); | |
1420 | ||
1421 | spin_unlock(cfqd->queue->queue_lock); | |
22e2c507 JA |
1422 | } |
1423 | ||
1424 | /* | |
1425 | * callback from sys_ioprio_set, irqs are disabled | |
1426 | */ | |
1427 | static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) | |
1428 | { | |
a6a0763a | 1429 | struct cfq_io_context *cic; |
e2d74ac0 | 1430 | struct rb_node *n; |
a6a0763a | 1431 | |
3793c65c | 1432 | spin_lock(&cfq_exit_lock); |
a6a0763a | 1433 | |
e2d74ac0 JA |
1434 | n = rb_first(&ioc->cic_root); |
1435 | while (n != NULL) { | |
1436 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
3793c65c | 1437 | |
478a82b0 | 1438 | changed_ioprio(cic); |
e2d74ac0 JA |
1439 | n = rb_next(n); |
1440 | } | |
22e2c507 | 1441 | |
3793c65c | 1442 | spin_unlock(&cfq_exit_lock); |
a6a0763a | 1443 | |
22e2c507 JA |
1444 | return 0; |
1445 | } | |
1446 | ||
1447 | static struct cfq_queue * | |
6f325a13 | 1448 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, |
8267e268 | 1449 | gfp_t gfp_mask) |
22e2c507 JA |
1450 | { |
1451 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1452 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
6f325a13 | 1453 | unsigned short ioprio; |
22e2c507 JA |
1454 | |
1455 | retry: | |
6f325a13 | 1456 | ioprio = tsk->ioprio; |
3b18152c | 1457 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); |
22e2c507 JA |
1458 | |
1459 | if (!cfqq) { | |
1460 | if (new_cfqq) { | |
1461 | cfqq = new_cfqq; | |
1462 | new_cfqq = NULL; | |
1463 | } else if (gfp_mask & __GFP_WAIT) { | |
1464 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1465 | new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1466 | spin_lock_irq(cfqd->queue->queue_lock); | |
1467 | goto retry; | |
1468 | } else { | |
1469 | cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1470 | if (!cfqq) | |
1471 | goto out; | |
1472 | } | |
1473 | ||
1474 | memset(cfqq, 0, sizeof(*cfqq)); | |
1475 | ||
1476 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1477 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
22e2c507 JA |
1478 | INIT_LIST_HEAD(&cfqq->fifo); |
1479 | ||
1480 | cfqq->key = key; | |
1481 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1482 | atomic_set(&cfqq->ref, 0); | |
1483 | cfqq->cfqd = cfqd; | |
22e2c507 JA |
1484 | cfqq->service_last = 0; |
1485 | /* | |
1486 | * set ->slice_left to allow preemption for a new process | |
1487 | */ | |
1488 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
caaa5f9f | 1489 | cfq_mark_cfqq_idle_window(cfqq); |
3b18152c JA |
1490 | cfq_mark_cfqq_prio_changed(cfqq); |
1491 | cfq_init_prio_data(cfqq); | |
22e2c507 JA |
1492 | } |
1493 | ||
1494 | if (new_cfqq) | |
1495 | kmem_cache_free(cfq_pool, new_cfqq); | |
1496 | ||
1497 | atomic_inc(&cfqq->ref); | |
1498 | out: | |
1499 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1500 | return cfqq; | |
1501 | } | |
1502 | ||
dbecf3ab OH |
1503 | static void |
1504 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1505 | { | |
3793c65c | 1506 | spin_lock(&cfq_exit_lock); |
dbecf3ab | 1507 | rb_erase(&cic->rb_node, &ioc->cic_root); |
3793c65c JA |
1508 | list_del_init(&cic->queue_list); |
1509 | spin_unlock(&cfq_exit_lock); | |
dbecf3ab OH |
1510 | kmem_cache_free(cfq_ioc_pool, cic); |
1511 | atomic_dec(&ioc_count); | |
1512 | } | |
1513 | ||
e2d74ac0 JA |
1514 | static struct cfq_io_context * |
1515 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1516 | { | |
dbecf3ab | 1517 | struct rb_node *n; |
e2d74ac0 | 1518 | struct cfq_io_context *cic; |
be3b0753 | 1519 | void *k, *key = cfqd; |
e2d74ac0 | 1520 | |
dbecf3ab OH |
1521 | restart: |
1522 | n = ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1523 | while (n) { |
1524 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1525 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1526 | k = cic->key; | |
1527 | if (unlikely(!k)) { | |
dbecf3ab OH |
1528 | cfq_drop_dead_cic(ioc, cic); |
1529 | goto restart; | |
1530 | } | |
e2d74ac0 | 1531 | |
be3b0753 | 1532 | if (key < k) |
e2d74ac0 | 1533 | n = n->rb_left; |
be3b0753 | 1534 | else if (key > k) |
e2d74ac0 JA |
1535 | n = n->rb_right; |
1536 | else | |
1537 | return cic; | |
1538 | } | |
1539 | ||
1540 | return NULL; | |
1541 | } | |
1542 | ||
1543 | static inline void | |
1544 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1545 | struct cfq_io_context *cic) | |
1546 | { | |
dbecf3ab OH |
1547 | struct rb_node **p; |
1548 | struct rb_node *parent; | |
e2d74ac0 | 1549 | struct cfq_io_context *__cic; |
be3b0753 | 1550 | void *k; |
e2d74ac0 | 1551 | |
e2d74ac0 JA |
1552 | cic->ioc = ioc; |
1553 | cic->key = cfqd; | |
1554 | ||
1555 | ioc->set_ioprio = cfq_ioc_set_ioprio; | |
dbecf3ab OH |
1556 | restart: |
1557 | parent = NULL; | |
1558 | p = &ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1559 | while (*p) { |
1560 | parent = *p; | |
1561 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1562 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1563 | k = __cic->key; | |
1564 | if (unlikely(!k)) { | |
dbecf3ab OH |
1565 | cfq_drop_dead_cic(ioc, cic); |
1566 | goto restart; | |
1567 | } | |
e2d74ac0 | 1568 | |
be3b0753 | 1569 | if (cic->key < k) |
e2d74ac0 | 1570 | p = &(*p)->rb_left; |
be3b0753 | 1571 | else if (cic->key > k) |
e2d74ac0 JA |
1572 | p = &(*p)->rb_right; |
1573 | else | |
1574 | BUG(); | |
1575 | } | |
1576 | ||
3793c65c | 1577 | spin_lock(&cfq_exit_lock); |
e2d74ac0 JA |
1578 | rb_link_node(&cic->rb_node, parent, p); |
1579 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
1580 | list_add(&cic->queue_list, &cfqd->cic_list); | |
3793c65c | 1581 | spin_unlock(&cfq_exit_lock); |
e2d74ac0 JA |
1582 | } |
1583 | ||
1da177e4 LT |
1584 | /* |
1585 | * Setup general io context and cfq io context. There can be several cfq | |
1586 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1587 | * than one device managed by cfq. |
1da177e4 LT |
1588 | */ |
1589 | static struct cfq_io_context * | |
e2d74ac0 | 1590 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1591 | { |
22e2c507 | 1592 | struct io_context *ioc = NULL; |
1da177e4 | 1593 | struct cfq_io_context *cic; |
1da177e4 | 1594 | |
22e2c507 | 1595 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1596 | |
22e2c507 | 1597 | ioc = get_io_context(gfp_mask); |
1da177e4 LT |
1598 | if (!ioc) |
1599 | return NULL; | |
1600 | ||
e2d74ac0 JA |
1601 | cic = cfq_cic_rb_lookup(cfqd, ioc); |
1602 | if (cic) | |
1603 | goto out; | |
1da177e4 | 1604 | |
e2d74ac0 JA |
1605 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1606 | if (cic == NULL) | |
1607 | goto err; | |
1da177e4 | 1608 | |
e2d74ac0 | 1609 | cfq_cic_link(cfqd, ioc, cic); |
1da177e4 | 1610 | out: |
1da177e4 LT |
1611 | return cic; |
1612 | err: | |
1613 | put_io_context(ioc); | |
1614 | return NULL; | |
1615 | } | |
1616 | ||
22e2c507 JA |
1617 | static void |
1618 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1619 | { |
22e2c507 | 1620 | unsigned long elapsed, ttime; |
1da177e4 | 1621 | |
22e2c507 JA |
1622 | /* |
1623 | * if this context already has stuff queued, thinktime is from | |
1624 | * last queue not last end | |
1625 | */ | |
1626 | #if 0 | |
1627 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1628 | elapsed = jiffies - cic->last_end_request; | |
1629 | else | |
1630 | elapsed = jiffies - cic->last_queue; | |
1631 | #else | |
1632 | elapsed = jiffies - cic->last_end_request; | |
1633 | #endif | |
1da177e4 | 1634 | |
22e2c507 | 1635 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
db3b5848 | 1636 | |
22e2c507 JA |
1637 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1638 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1639 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1640 | } | |
1da177e4 | 1641 | |
206dc69b JA |
1642 | static void |
1643 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
1644 | struct cfq_rq *crq) | |
1645 | { | |
1646 | sector_t sdist; | |
1647 | u64 total; | |
1648 | ||
1649 | if (cic->last_request_pos < crq->request->sector) | |
1650 | sdist = crq->request->sector - cic->last_request_pos; | |
1651 | else | |
1652 | sdist = cic->last_request_pos - crq->request->sector; | |
1653 | ||
1654 | /* | |
1655 | * Don't allow the seek distance to get too large from the | |
1656 | * odd fragment, pagein, etc | |
1657 | */ | |
1658 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1659 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1660 | else | |
1661 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1662 | ||
1663 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1664 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1665 | total = cic->seek_total + (cic->seek_samples/2); | |
1666 | do_div(total, cic->seek_samples); | |
1667 | cic->seek_mean = (sector_t)total; | |
1668 | } | |
1da177e4 | 1669 | |
22e2c507 JA |
1670 | /* |
1671 | * Disable idle window if the process thinks too long or seeks so much that | |
1672 | * it doesn't matter | |
1673 | */ | |
1674 | static void | |
1675 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1676 | struct cfq_io_context *cic) | |
1677 | { | |
3b18152c | 1678 | int enable_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1679 | |
caaa5f9f JA |
1680 | if (!cic->ioc->task || !cfqd->cfq_slice_idle || |
1681 | (cfqd->hw_tag && CIC_SEEKY(cic))) | |
22e2c507 JA |
1682 | enable_idle = 0; |
1683 | else if (sample_valid(cic->ttime_samples)) { | |
1684 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1685 | enable_idle = 0; | |
1686 | else | |
1687 | enable_idle = 1; | |
1da177e4 LT |
1688 | } |
1689 | ||
3b18152c JA |
1690 | if (enable_idle) |
1691 | cfq_mark_cfqq_idle_window(cfqq); | |
1692 | else | |
1693 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1694 | } |
1da177e4 | 1695 | |
22e2c507 JA |
1696 | |
1697 | /* | |
1698 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1699 | * no or if we aren't sure, a 1 will cause a preempt. | |
1700 | */ | |
1701 | static int | |
1702 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1703 | struct cfq_rq *crq) | |
1704 | { | |
1705 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1706 | ||
1707 | if (cfq_class_idle(new_cfqq)) | |
1708 | return 0; | |
1709 | ||
1710 | if (!cfqq) | |
caaa5f9f | 1711 | return 0; |
22e2c507 JA |
1712 | |
1713 | if (cfq_class_idle(cfqq)) | |
1714 | return 1; | |
3b18152c | 1715 | if (!cfq_cfqq_wait_request(new_cfqq)) |
22e2c507 JA |
1716 | return 0; |
1717 | /* | |
1718 | * if it doesn't have slice left, forget it | |
1719 | */ | |
1720 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1721 | return 0; | |
3b18152c | 1722 | if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 JA |
1723 | return 1; |
1724 | ||
1725 | return 0; | |
1726 | } | |
1727 | ||
1728 | /* | |
1729 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1730 | * let it have half of its nominal slice. | |
1731 | */ | |
1732 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1733 | { | |
1734 | struct cfq_queue *__cfqq, *next; | |
1735 | ||
1736 | list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) | |
1737 | cfq_resort_rr_list(__cfqq, 1); | |
1738 | ||
1739 | if (!cfqq->slice_left) | |
1740 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1741 | ||
1742 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
caaa5f9f | 1743 | cfq_slice_expired(cfqd, 1); |
22e2c507 JA |
1744 | __cfq_set_active_queue(cfqd, cfqq); |
1745 | } | |
1746 | ||
1747 | /* | |
1748 | * should really be a ll_rw_blk.c helper | |
1749 | */ | |
1750 | static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1751 | { | |
1752 | request_queue_t *q = cfqd->queue; | |
1753 | ||
1754 | if (!blk_queue_plugged(q)) | |
1755 | q->request_fn(q); | |
1756 | else | |
1757 | __generic_unplug_device(q); | |
1758 | } | |
1759 | ||
1760 | /* | |
1761 | * Called when a new fs request (crq) is added (to cfqq). Check if there's | |
1762 | * something we should do about it | |
1763 | */ | |
1764 | static void | |
1765 | cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1766 | struct cfq_rq *crq) | |
1767 | { | |
fd61af03 | 1768 | struct cfq_io_context *cic = crq->io_context; |
12e9fddd | 1769 | |
9c2c38a1 JA |
1770 | /* |
1771 | * we never wait for an async request and we don't allow preemption | |
1772 | * of an async request. so just return early | |
1773 | */ | |
12e9fddd JA |
1774 | if (!cfq_crq_is_sync(crq)) { |
1775 | /* | |
1776 | * sync process issued an async request, if it's waiting | |
1777 | * then expire it and kick rq handling. | |
1778 | */ | |
1779 | if (cic == cfqd->active_cic && | |
1780 | del_timer(&cfqd->idle_slice_timer)) { | |
1781 | cfq_slice_expired(cfqd, 0); | |
1782 | cfq_start_queueing(cfqd, cfqq); | |
1783 | } | |
9c2c38a1 | 1784 | return; |
12e9fddd | 1785 | } |
22e2c507 | 1786 | |
9c2c38a1 | 1787 | cfq_update_io_thinktime(cfqd, cic); |
206dc69b | 1788 | cfq_update_io_seektime(cfqd, cic, crq); |
9c2c38a1 JA |
1789 | cfq_update_idle_window(cfqd, cfqq, cic); |
1790 | ||
1791 | cic->last_queue = jiffies; | |
206dc69b | 1792 | cic->last_request_pos = crq->request->sector + crq->request->nr_sectors; |
22e2c507 JA |
1793 | |
1794 | if (cfqq == cfqd->active_queue) { | |
1795 | /* | |
1796 | * if we are waiting for a request for this queue, let it rip | |
1797 | * immediately and flag that we must not expire this queue | |
1798 | * just now | |
1799 | */ | |
3b18152c JA |
1800 | if (cfq_cfqq_wait_request(cfqq)) { |
1801 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 JA |
1802 | del_timer(&cfqd->idle_slice_timer); |
1803 | cfq_start_queueing(cfqd, cfqq); | |
1804 | } | |
1805 | } else if (cfq_should_preempt(cfqd, cfqq, crq)) { | |
1806 | /* | |
1807 | * not the active queue - expire current slice if it is | |
1808 | * idle and has expired it's mean thinktime or this new queue | |
1809 | * has some old slice time left and is of higher priority | |
1810 | */ | |
1811 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1812 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
1813 | cfq_start_queueing(cfqd, cfqq); |
1814 | } | |
1da177e4 LT |
1815 | } |
1816 | ||
b4878f24 | 1817 | static void cfq_insert_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1818 | { |
b4878f24 | 1819 | struct cfq_data *cfqd = q->elevator->elevator_data; |
22e2c507 JA |
1820 | struct cfq_rq *crq = RQ_DATA(rq); |
1821 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1822 | ||
1823 | cfq_init_prio_data(cfqq); | |
1da177e4 LT |
1824 | |
1825 | cfq_add_crq_rb(crq); | |
1da177e4 | 1826 | |
22e2c507 JA |
1827 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1828 | ||
98b11471 | 1829 | if (rq_mergeable(rq)) |
22e2c507 JA |
1830 | cfq_add_crq_hash(cfqd, crq); |
1831 | ||
22e2c507 | 1832 | cfq_crq_enqueued(cfqd, cfqq, crq); |
1da177e4 LT |
1833 | } |
1834 | ||
1da177e4 LT |
1835 | static void cfq_completed_request(request_queue_t *q, struct request *rq) |
1836 | { | |
1837 | struct cfq_rq *crq = RQ_DATA(rq); | |
b4878f24 JA |
1838 | struct cfq_queue *cfqq = crq->cfq_queue; |
1839 | struct cfq_data *cfqd = cfqq->cfqd; | |
1840 | const int sync = cfq_crq_is_sync(crq); | |
1841 | unsigned long now; | |
1da177e4 | 1842 | |
b4878f24 | 1843 | now = jiffies; |
1da177e4 | 1844 | |
b4878f24 JA |
1845 | WARN_ON(!cfqd->rq_in_driver); |
1846 | WARN_ON(!cfqq->on_dispatch[sync]); | |
1847 | cfqd->rq_in_driver--; | |
1848 | cfqq->on_dispatch[sync]--; | |
1da177e4 | 1849 | |
b4878f24 JA |
1850 | if (!cfq_class_idle(cfqq)) |
1851 | cfqd->last_end_request = now; | |
3b18152c | 1852 | |
b4878f24 JA |
1853 | if (!cfq_cfqq_dispatched(cfqq)) { |
1854 | if (cfq_cfqq_on_rr(cfqq)) { | |
1855 | cfqq->service_last = now; | |
1856 | cfq_resort_rr_list(cfqq, 0); | |
1857 | } | |
1da177e4 LT |
1858 | } |
1859 | ||
caaa5f9f | 1860 | if (sync) |
b4878f24 | 1861 | crq->io_context->last_end_request = now; |
caaa5f9f JA |
1862 | |
1863 | /* | |
1864 | * If this is the active queue, check if it needs to be expired, | |
1865 | * or if we want to idle in case it has no pending requests. | |
1866 | */ | |
1867 | if (cfqd->active_queue == cfqq) { | |
1868 | if (time_after(now, cfqq->slice_end)) | |
1869 | cfq_slice_expired(cfqd, 0); | |
dd67d051 | 1870 | else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) { |
caaa5f9f JA |
1871 | if (!cfq_arm_slice_timer(cfqd, cfqq)) |
1872 | cfq_schedule_dispatch(cfqd); | |
1873 | } | |
1874 | } | |
1da177e4 LT |
1875 | } |
1876 | ||
1877 | static struct request * | |
1878 | cfq_former_request(request_queue_t *q, struct request *rq) | |
1879 | { | |
1880 | struct cfq_rq *crq = RQ_DATA(rq); | |
1881 | struct rb_node *rbprev = rb_prev(&crq->rb_node); | |
1882 | ||
1883 | if (rbprev) | |
1884 | return rb_entry_crq(rbprev)->request; | |
1885 | ||
1886 | return NULL; | |
1887 | } | |
1888 | ||
1889 | static struct request * | |
1890 | cfq_latter_request(request_queue_t *q, struct request *rq) | |
1891 | { | |
1892 | struct cfq_rq *crq = RQ_DATA(rq); | |
1893 | struct rb_node *rbnext = rb_next(&crq->rb_node); | |
1894 | ||
1895 | if (rbnext) | |
1896 | return rb_entry_crq(rbnext)->request; | |
1897 | ||
1898 | return NULL; | |
1899 | } | |
1900 | ||
22e2c507 JA |
1901 | /* |
1902 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1903 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1904 | */ | |
1905 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1906 | { |
22e2c507 JA |
1907 | const int ioprio_class = cfqq->ioprio_class; |
1908 | const int ioprio = cfqq->ioprio; | |
1da177e4 | 1909 | |
22e2c507 JA |
1910 | if (has_fs_excl()) { |
1911 | /* | |
1912 | * boost idle prio on transactions that would lock out other | |
1913 | * users of the filesystem | |
1914 | */ | |
1915 | if (cfq_class_idle(cfqq)) | |
1916 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1917 | if (cfqq->ioprio > IOPRIO_NORM) | |
1918 | cfqq->ioprio = IOPRIO_NORM; | |
1919 | } else { | |
1920 | /* | |
1921 | * check if we need to unboost the queue | |
1922 | */ | |
1923 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1924 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1925 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1926 | cfqq->ioprio = cfqq->org_ioprio; | |
1927 | } | |
1da177e4 | 1928 | |
22e2c507 JA |
1929 | /* |
1930 | * refile between round-robin lists if we moved the priority class | |
1931 | */ | |
1932 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
3b18152c | 1933 | cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1934 | cfq_resort_rr_list(cfqq, 0); |
1935 | } | |
1da177e4 | 1936 | |
22e2c507 JA |
1937 | static inline int |
1938 | __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1939 | struct task_struct *task, int rw) | |
1940 | { | |
3b18152c | 1941 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && |
99f95e52 | 1942 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1943 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1944 | return ELV_MQUEUE_MUST; |
3b18152c | 1945 | } |
1da177e4 | 1946 | |
22e2c507 | 1947 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
1948 | } |
1949 | ||
1950 | static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) | |
1951 | { | |
1952 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1953 | struct task_struct *tsk = current; | |
1954 | struct cfq_queue *cfqq; | |
1955 | ||
1956 | /* | |
1957 | * don't force setup of a queue from here, as a call to may_queue | |
1958 | * does not necessarily imply that a request actually will be queued. | |
1959 | * so just lookup a possibly existing queue, or return 'may queue' | |
1960 | * if that fails | |
1961 | */ | |
3b18152c | 1962 | cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); |
22e2c507 JA |
1963 | if (cfqq) { |
1964 | cfq_init_prio_data(cfqq); | |
1965 | cfq_prio_boost(cfqq); | |
1966 | ||
1967 | return __cfq_may_queue(cfqd, cfqq, tsk, rw); | |
1968 | } | |
1969 | ||
1970 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1971 | } |
1972 | ||
1973 | static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) | |
1974 | { | |
22e2c507 | 1975 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 | 1976 | |
271f18f1 JA |
1977 | if (unlikely(cfqd->rq_starved)) { |
1978 | struct request_list *rl = &q->rq; | |
1979 | ||
22e2c507 JA |
1980 | smp_mb(); |
1981 | if (waitqueue_active(&rl->wait[READ])) | |
1982 | wake_up(&rl->wait[READ]); | |
22e2c507 JA |
1983 | if (waitqueue_active(&rl->wait[WRITE])) |
1984 | wake_up(&rl->wait[WRITE]); | |
1985 | } | |
1da177e4 LT |
1986 | } |
1987 | ||
1988 | /* | |
1989 | * queue lock held here | |
1990 | */ | |
1991 | static void cfq_put_request(request_queue_t *q, struct request *rq) | |
1992 | { | |
1993 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1994 | struct cfq_rq *crq = RQ_DATA(rq); | |
1995 | ||
1996 | if (crq) { | |
1997 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 | 1998 | const int rw = rq_data_dir(rq); |
1da177e4 | 1999 | |
22e2c507 JA |
2000 | BUG_ON(!cfqq->allocated[rw]); |
2001 | cfqq->allocated[rw]--; | |
1da177e4 | 2002 | |
22e2c507 | 2003 | put_io_context(crq->io_context->ioc); |
1da177e4 LT |
2004 | |
2005 | mempool_free(crq, cfqd->crq_pool); | |
2006 | rq->elevator_private = NULL; | |
2007 | ||
1da177e4 LT |
2008 | cfq_check_waiters(q, cfqq); |
2009 | cfq_put_queue(cfqq); | |
2010 | } | |
2011 | } | |
2012 | ||
2013 | /* | |
22e2c507 | 2014 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2015 | */ |
22e2c507 JA |
2016 | static int |
2017 | cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, | |
8267e268 | 2018 | gfp_t gfp_mask) |
1da177e4 LT |
2019 | { |
2020 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 2021 | struct task_struct *tsk = current; |
1da177e4 LT |
2022 | struct cfq_io_context *cic; |
2023 | const int rw = rq_data_dir(rq); | |
3b18152c | 2024 | pid_t key = cfq_queue_pid(tsk, rw); |
22e2c507 | 2025 | struct cfq_queue *cfqq; |
1da177e4 LT |
2026 | struct cfq_rq *crq; |
2027 | unsigned long flags; | |
12a05732 | 2028 | int is_sync = key != CFQ_KEY_ASYNC; |
1da177e4 LT |
2029 | |
2030 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2031 | ||
e2d74ac0 | 2032 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2033 | |
1da177e4 LT |
2034 | spin_lock_irqsave(q->queue_lock, flags); |
2035 | ||
22e2c507 JA |
2036 | if (!cic) |
2037 | goto queue_fail; | |
2038 | ||
12a05732 | 2039 | if (!cic->cfqq[is_sync]) { |
6f325a13 | 2040 | cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask); |
22e2c507 JA |
2041 | if (!cfqq) |
2042 | goto queue_fail; | |
1da177e4 | 2043 | |
12a05732 | 2044 | cic->cfqq[is_sync] = cfqq; |
22e2c507 | 2045 | } else |
12a05732 | 2046 | cfqq = cic->cfqq[is_sync]; |
1da177e4 LT |
2047 | |
2048 | cfqq->allocated[rw]++; | |
3b18152c | 2049 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 JA |
2050 | cfqd->rq_starved = 0; |
2051 | atomic_inc(&cfqq->ref); | |
1da177e4 LT |
2052 | spin_unlock_irqrestore(q->queue_lock, flags); |
2053 | ||
1da177e4 LT |
2054 | crq = mempool_alloc(cfqd->crq_pool, gfp_mask); |
2055 | if (crq) { | |
dd67d051 | 2056 | RB_CLEAR_NODE(&crq->rb_node); |
1da177e4 LT |
2057 | crq->rb_key = 0; |
2058 | crq->request = rq; | |
2059 | INIT_HLIST_NODE(&crq->hash); | |
2060 | crq->cfq_queue = cfqq; | |
2061 | crq->io_context = cic; | |
3b18152c | 2062 | |
12a05732 | 2063 | if (is_sync) |
3b18152c JA |
2064 | cfq_mark_crq_is_sync(crq); |
2065 | else | |
2066 | cfq_clear_crq_is_sync(crq); | |
2067 | ||
1da177e4 | 2068 | rq->elevator_private = crq; |
1da177e4 LT |
2069 | return 0; |
2070 | } | |
2071 | ||
1da177e4 LT |
2072 | spin_lock_irqsave(q->queue_lock, flags); |
2073 | cfqq->allocated[rw]--; | |
22e2c507 | 2074 | if (!(cfqq->allocated[0] + cfqq->allocated[1])) |
3b18152c | 2075 | cfq_mark_cfqq_must_alloc(cfqq); |
1da177e4 | 2076 | cfq_put_queue(cfqq); |
22e2c507 JA |
2077 | queue_fail: |
2078 | if (cic) | |
2079 | put_io_context(cic->ioc); | |
2080 | /* | |
2081 | * mark us rq allocation starved. we need to kickstart the process | |
2082 | * ourselves if there are no pending requests that can do it for us. | |
2083 | * that would be an extremely rare OOM situation | |
2084 | */ | |
2085 | cfqd->rq_starved = 1; | |
3b18152c | 2086 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2087 | spin_unlock_irqrestore(q->queue_lock, flags); |
2088 | return 1; | |
2089 | } | |
2090 | ||
22e2c507 JA |
2091 | static void cfq_kick_queue(void *data) |
2092 | { | |
2093 | request_queue_t *q = data; | |
2094 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2095 | unsigned long flags; | |
2096 | ||
2097 | spin_lock_irqsave(q->queue_lock, flags); | |
2098 | ||
2099 | if (cfqd->rq_starved) { | |
2100 | struct request_list *rl = &q->rq; | |
2101 | ||
2102 | /* | |
2103 | * we aren't guaranteed to get a request after this, but we | |
2104 | * have to be opportunistic | |
2105 | */ | |
2106 | smp_mb(); | |
2107 | if (waitqueue_active(&rl->wait[READ])) | |
2108 | wake_up(&rl->wait[READ]); | |
2109 | if (waitqueue_active(&rl->wait[WRITE])) | |
2110 | wake_up(&rl->wait[WRITE]); | |
2111 | } | |
2112 | ||
2113 | blk_remove_plug(q); | |
2114 | q->request_fn(q); | |
2115 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2116 | } | |
2117 | ||
2118 | /* | |
2119 | * Timer running if the active_queue is currently idling inside its time slice | |
2120 | */ | |
2121 | static void cfq_idle_slice_timer(unsigned long data) | |
2122 | { | |
2123 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2124 | struct cfq_queue *cfqq; | |
2125 | unsigned long flags; | |
2126 | ||
2127 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2128 | ||
2129 | if ((cfqq = cfqd->active_queue) != NULL) { | |
2130 | unsigned long now = jiffies; | |
2131 | ||
2132 | /* | |
2133 | * expired | |
2134 | */ | |
2135 | if (time_after(now, cfqq->slice_end)) | |
2136 | goto expire; | |
2137 | ||
2138 | /* | |
2139 | * only expire and reinvoke request handler, if there are | |
2140 | * other queues with pending requests | |
2141 | */ | |
caaa5f9f | 2142 | if (!cfqd->busy_queues) |
22e2c507 | 2143 | goto out_cont; |
22e2c507 JA |
2144 | |
2145 | /* | |
2146 | * not expired and it has a request pending, let it dispatch | |
2147 | */ | |
dd67d051 | 2148 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) { |
3b18152c | 2149 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2150 | goto out_kick; |
2151 | } | |
2152 | } | |
2153 | expire: | |
2154 | cfq_slice_expired(cfqd, 0); | |
2155 | out_kick: | |
3b18152c | 2156 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2157 | out_cont: |
2158 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2159 | } | |
2160 | ||
2161 | /* | |
2162 | * Timer running if an idle class queue is waiting for service | |
2163 | */ | |
2164 | static void cfq_idle_class_timer(unsigned long data) | |
2165 | { | |
2166 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2167 | unsigned long flags, end; | |
2168 | ||
2169 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2170 | ||
2171 | /* | |
2172 | * race with a non-idle queue, reset timer | |
2173 | */ | |
2174 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
ae818a38 JA |
2175 | if (!time_after_eq(jiffies, end)) |
2176 | mod_timer(&cfqd->idle_class_timer, end); | |
2177 | else | |
3b18152c | 2178 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2179 | |
2180 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2181 | } | |
2182 | ||
3b18152c JA |
2183 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2184 | { | |
2185 | del_timer_sync(&cfqd->idle_slice_timer); | |
2186 | del_timer_sync(&cfqd->idle_class_timer); | |
2187 | blk_sync_queue(cfqd->queue); | |
2188 | } | |
22e2c507 | 2189 | |
1da177e4 LT |
2190 | static void cfq_exit_queue(elevator_t *e) |
2191 | { | |
22e2c507 | 2192 | struct cfq_data *cfqd = e->elevator_data; |
d9ff4187 | 2193 | request_queue_t *q = cfqd->queue; |
22e2c507 | 2194 | |
3b18152c | 2195 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2196 | |
3793c65c | 2197 | spin_lock(&cfq_exit_lock); |
d9ff4187 | 2198 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2199 | |
d9ff4187 AV |
2200 | if (cfqd->active_queue) |
2201 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); | |
e2d74ac0 JA |
2202 | |
2203 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2204 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2205 | struct cfq_io_context, | |
2206 | queue_list); | |
2207 | if (cic->cfqq[ASYNC]) { | |
2208 | cfq_put_queue(cic->cfqq[ASYNC]); | |
2209 | cic->cfqq[ASYNC] = NULL; | |
2210 | } | |
2211 | if (cic->cfqq[SYNC]) { | |
2212 | cfq_put_queue(cic->cfqq[SYNC]); | |
2213 | cic->cfqq[SYNC] = NULL; | |
2214 | } | |
2215 | cic->key = NULL; | |
2216 | list_del_init(&cic->queue_list); | |
2217 | } | |
e2d74ac0 | 2218 | |
d9ff4187 | 2219 | spin_unlock_irq(q->queue_lock); |
3793c65c | 2220 | spin_unlock(&cfq_exit_lock); |
a90d742e AV |
2221 | |
2222 | cfq_shutdown_timer_wq(cfqd); | |
2223 | ||
2224 | mempool_destroy(cfqd->crq_pool); | |
2225 | kfree(cfqd->crq_hash); | |
2226 | kfree(cfqd->cfq_hash); | |
2227 | kfree(cfqd); | |
1da177e4 LT |
2228 | } |
2229 | ||
bc1c1169 | 2230 | static void *cfq_init_queue(request_queue_t *q, elevator_t *e) |
1da177e4 LT |
2231 | { |
2232 | struct cfq_data *cfqd; | |
2233 | int i; | |
2234 | ||
2235 | cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); | |
2236 | if (!cfqd) | |
bc1c1169 | 2237 | return NULL; |
1da177e4 LT |
2238 | |
2239 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 JA |
2240 | |
2241 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2242 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2243 | ||
2244 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2245 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2246 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
1da177e4 | 2247 | INIT_LIST_HEAD(&cfqd->empty_list); |
d9ff4187 | 2248 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 LT |
2249 | |
2250 | cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); | |
2251 | if (!cfqd->crq_hash) | |
2252 | goto out_crqhash; | |
2253 | ||
2254 | cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); | |
2255 | if (!cfqd->cfq_hash) | |
2256 | goto out_cfqhash; | |
2257 | ||
93d2341c | 2258 | cfqd->crq_pool = mempool_create_slab_pool(BLKDEV_MIN_RQ, crq_pool); |
1da177e4 LT |
2259 | if (!cfqd->crq_pool) |
2260 | goto out_crqpool; | |
2261 | ||
2262 | for (i = 0; i < CFQ_MHASH_ENTRIES; i++) | |
2263 | INIT_HLIST_HEAD(&cfqd->crq_hash[i]); | |
2264 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2265 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2266 | ||
1da177e4 | 2267 | cfqd->queue = q; |
1da177e4 | 2268 | |
22e2c507 JA |
2269 | init_timer(&cfqd->idle_slice_timer); |
2270 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2271 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2272 | ||
2273 | init_timer(&cfqd->idle_class_timer); | |
2274 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2275 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2276 | ||
2277 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); | |
2278 | ||
1da177e4 LT |
2279 | cfqd->cfq_queued = cfq_queued; |
2280 | cfqd->cfq_quantum = cfq_quantum; | |
22e2c507 JA |
2281 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2282 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2283 | cfqd->cfq_back_max = cfq_back_max; |
2284 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2285 | cfqd->cfq_slice[0] = cfq_slice_async; |
2286 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2287 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2288 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2289 | |
bc1c1169 | 2290 | return cfqd; |
1da177e4 LT |
2291 | out_crqpool: |
2292 | kfree(cfqd->cfq_hash); | |
2293 | out_cfqhash: | |
2294 | kfree(cfqd->crq_hash); | |
2295 | out_crqhash: | |
2296 | kfree(cfqd); | |
bc1c1169 | 2297 | return NULL; |
1da177e4 LT |
2298 | } |
2299 | ||
2300 | static void cfq_slab_kill(void) | |
2301 | { | |
2302 | if (crq_pool) | |
2303 | kmem_cache_destroy(crq_pool); | |
2304 | if (cfq_pool) | |
2305 | kmem_cache_destroy(cfq_pool); | |
2306 | if (cfq_ioc_pool) | |
2307 | kmem_cache_destroy(cfq_ioc_pool); | |
2308 | } | |
2309 | ||
2310 | static int __init cfq_slab_setup(void) | |
2311 | { | |
2312 | crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, | |
2313 | NULL, NULL); | |
2314 | if (!crq_pool) | |
2315 | goto fail; | |
2316 | ||
2317 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2318 | NULL, NULL); | |
2319 | if (!cfq_pool) | |
2320 | goto fail; | |
2321 | ||
2322 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2323 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2324 | if (!cfq_ioc_pool) | |
2325 | goto fail; | |
2326 | ||
2327 | return 0; | |
2328 | fail: | |
2329 | cfq_slab_kill(); | |
2330 | return -ENOMEM; | |
2331 | } | |
2332 | ||
1da177e4 LT |
2333 | /* |
2334 | * sysfs parts below --> | |
2335 | */ | |
1da177e4 LT |
2336 | |
2337 | static ssize_t | |
2338 | cfq_var_show(unsigned int var, char *page) | |
2339 | { | |
2340 | return sprintf(page, "%d\n", var); | |
2341 | } | |
2342 | ||
2343 | static ssize_t | |
2344 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2345 | { | |
2346 | char *p = (char *) page; | |
2347 | ||
2348 | *var = simple_strtoul(p, &p, 10); | |
2349 | return count; | |
2350 | } | |
2351 | ||
1da177e4 | 2352 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2353 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2354 | { \ |
3d1ab40f | 2355 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2356 | unsigned int __data = __VAR; \ |
2357 | if (__CONV) \ | |
2358 | __data = jiffies_to_msecs(__data); \ | |
2359 | return cfq_var_show(__data, (page)); \ | |
2360 | } | |
2361 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2362 | SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); | |
22e2c507 JA |
2363 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2364 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2365 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2366 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2367 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2368 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2369 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2370 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2371 | #undef SHOW_FUNCTION |
2372 | ||
2373 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2374 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2375 | { \ |
3d1ab40f | 2376 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2377 | unsigned int __data; \ |
2378 | int ret = cfq_var_store(&__data, (page), count); \ | |
2379 | if (__data < (MIN)) \ | |
2380 | __data = (MIN); \ | |
2381 | else if (__data > (MAX)) \ | |
2382 | __data = (MAX); \ | |
2383 | if (__CONV) \ | |
2384 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2385 | else \ | |
2386 | *(__PTR) = __data; \ | |
2387 | return ret; \ | |
2388 | } | |
2389 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2390 | STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); | |
22e2c507 JA |
2391 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2392 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2393 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2394 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2395 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2396 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2397 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2398 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2399 | #undef STORE_FUNCTION |
2400 | ||
e572ec7e AV |
2401 | #define CFQ_ATTR(name) \ |
2402 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2403 | ||
2404 | static struct elv_fs_entry cfq_attrs[] = { | |
2405 | CFQ_ATTR(quantum), | |
2406 | CFQ_ATTR(queued), | |
2407 | CFQ_ATTR(fifo_expire_sync), | |
2408 | CFQ_ATTR(fifo_expire_async), | |
2409 | CFQ_ATTR(back_seek_max), | |
2410 | CFQ_ATTR(back_seek_penalty), | |
2411 | CFQ_ATTR(slice_sync), | |
2412 | CFQ_ATTR(slice_async), | |
2413 | CFQ_ATTR(slice_async_rq), | |
2414 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2415 | __ATTR_NULL |
1da177e4 LT |
2416 | }; |
2417 | ||
1da177e4 LT |
2418 | static struct elevator_type iosched_cfq = { |
2419 | .ops = { | |
2420 | .elevator_merge_fn = cfq_merge, | |
2421 | .elevator_merged_fn = cfq_merged_request, | |
2422 | .elevator_merge_req_fn = cfq_merged_requests, | |
b4878f24 | 2423 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2424 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2425 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2426 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2427 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2428 | .elevator_completed_req_fn = cfq_completed_request, | |
2429 | .elevator_former_req_fn = cfq_former_request, | |
2430 | .elevator_latter_req_fn = cfq_latter_request, | |
2431 | .elevator_set_req_fn = cfq_set_request, | |
2432 | .elevator_put_req_fn = cfq_put_request, | |
2433 | .elevator_may_queue_fn = cfq_may_queue, | |
2434 | .elevator_init_fn = cfq_init_queue, | |
2435 | .elevator_exit_fn = cfq_exit_queue, | |
e17a9489 | 2436 | .trim = cfq_trim, |
1da177e4 | 2437 | }, |
3d1ab40f | 2438 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2439 | .elevator_name = "cfq", |
2440 | .elevator_owner = THIS_MODULE, | |
2441 | }; | |
2442 | ||
2443 | static int __init cfq_init(void) | |
2444 | { | |
2445 | int ret; | |
2446 | ||
22e2c507 JA |
2447 | /* |
2448 | * could be 0 on HZ < 1000 setups | |
2449 | */ | |
2450 | if (!cfq_slice_async) | |
2451 | cfq_slice_async = 1; | |
2452 | if (!cfq_slice_idle) | |
2453 | cfq_slice_idle = 1; | |
2454 | ||
1da177e4 LT |
2455 | if (cfq_slab_setup()) |
2456 | return -ENOMEM; | |
2457 | ||
2458 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2459 | if (ret) |
2460 | cfq_slab_kill(); | |
1da177e4 | 2461 | |
1da177e4 LT |
2462 | return ret; |
2463 | } | |
2464 | ||
2465 | static void __exit cfq_exit(void) | |
2466 | { | |
334e94de | 2467 | DECLARE_COMPLETION(all_gone); |
1da177e4 | 2468 | elv_unregister(&iosched_cfq); |
334e94de | 2469 | ioc_gone = &all_gone; |
fba82272 OH |
2470 | /* ioc_gone's update must be visible before reading ioc_count */ |
2471 | smp_wmb(); | |
334e94de | 2472 | if (atomic_read(&ioc_count)) |
fba82272 | 2473 | wait_for_completion(ioc_gone); |
334e94de | 2474 | synchronize_rcu(); |
83521d3e | 2475 | cfq_slab_kill(); |
1da177e4 LT |
2476 | } |
2477 | ||
2478 | module_init(cfq_init); | |
2479 | module_exit(cfq_exit); | |
2480 | ||
2481 | MODULE_AUTHOR("Jens Axboe"); | |
2482 | MODULE_LICENSE("GPL"); | |
2483 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |