Commit | Line | Data |
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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; |
206dc69b | 29 | static int cfq_slice_idle = HZ / 70; |
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 | |
a6a0763a AV |
36 | static DEFINE_RWLOCK(cfq_exit_lock); |
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 | */ | |
63 | #define RB_NONE (2) | |
64 | #define RB_EMPTY(node) ((node)->rb_node == NULL) | |
65 | #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE | |
66 | #define RB_CLEAR(node) do { \ | |
67 | (node)->rb_parent = NULL; \ | |
68 | RB_CLEAR_COLOR((node)); \ | |
69 | (node)->rb_right = NULL; \ | |
70 | (node)->rb_left = NULL; \ | |
71 | } while (0) | |
72 | #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) | |
1da177e4 LT |
73 | #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) |
74 | #define rq_rb_key(rq) (rq)->sector | |
75 | ||
1da177e4 LT |
76 | static kmem_cache_t *crq_pool; |
77 | static kmem_cache_t *cfq_pool; | |
78 | static kmem_cache_t *cfq_ioc_pool; | |
79 | ||
334e94de AV |
80 | static atomic_t ioc_count = ATOMIC_INIT(0); |
81 | static struct completion *ioc_gone; | |
82 | ||
22e2c507 JA |
83 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
84 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
85 | #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) | |
86 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
87 | ||
3b18152c JA |
88 | #define ASYNC (0) |
89 | #define SYNC (1) | |
90 | ||
91 | #define cfq_cfqq_dispatched(cfqq) \ | |
92 | ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) | |
93 | ||
94 | #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) | |
95 | ||
96 | #define cfq_cfqq_sync(cfqq) \ | |
97 | (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) | |
22e2c507 | 98 | |
206dc69b JA |
99 | #define sample_valid(samples) ((samples) > 80) |
100 | ||
22e2c507 JA |
101 | /* |
102 | * Per block device queue structure | |
103 | */ | |
1da177e4 | 104 | struct cfq_data { |
22e2c507 JA |
105 | request_queue_t *queue; |
106 | ||
107 | /* | |
108 | * rr list of queues with requests and the count of them | |
109 | */ | |
110 | struct list_head rr_list[CFQ_PRIO_LISTS]; | |
111 | struct list_head busy_rr; | |
112 | struct list_head cur_rr; | |
113 | struct list_head idle_rr; | |
114 | unsigned int busy_queues; | |
115 | ||
116 | /* | |
117 | * non-ordered list of empty cfqq's | |
118 | */ | |
1da177e4 LT |
119 | struct list_head empty_list; |
120 | ||
22e2c507 JA |
121 | /* |
122 | * cfqq lookup hash | |
123 | */ | |
1da177e4 | 124 | struct hlist_head *cfq_hash; |
1da177e4 | 125 | |
22e2c507 JA |
126 | /* |
127 | * global crq hash for all queues | |
128 | */ | |
129 | struct hlist_head *crq_hash; | |
1da177e4 LT |
130 | |
131 | unsigned int max_queued; | |
132 | ||
22e2c507 | 133 | mempool_t *crq_pool; |
1da177e4 | 134 | |
22e2c507 | 135 | int rq_in_driver; |
1da177e4 | 136 | |
22e2c507 JA |
137 | /* |
138 | * schedule slice state info | |
139 | */ | |
140 | /* | |
141 | * idle window management | |
142 | */ | |
143 | struct timer_list idle_slice_timer; | |
144 | struct work_struct unplug_work; | |
1da177e4 | 145 | |
22e2c507 JA |
146 | struct cfq_queue *active_queue; |
147 | struct cfq_io_context *active_cic; | |
148 | int cur_prio, cur_end_prio; | |
149 | unsigned int dispatch_slice; | |
150 | ||
151 | struct timer_list idle_class_timer; | |
1da177e4 LT |
152 | |
153 | sector_t last_sector; | |
22e2c507 | 154 | unsigned long last_end_request; |
1da177e4 | 155 | |
22e2c507 | 156 | unsigned int rq_starved; |
1da177e4 LT |
157 | |
158 | /* | |
159 | * tunables, see top of file | |
160 | */ | |
161 | unsigned int cfq_quantum; | |
162 | unsigned int cfq_queued; | |
22e2c507 | 163 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
164 | unsigned int cfq_back_penalty; |
165 | unsigned int cfq_back_max; | |
22e2c507 JA |
166 | unsigned int cfq_slice[2]; |
167 | unsigned int cfq_slice_async_rq; | |
168 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
169 | |
170 | struct list_head cic_list; | |
1da177e4 LT |
171 | }; |
172 | ||
22e2c507 JA |
173 | /* |
174 | * Per process-grouping structure | |
175 | */ | |
1da177e4 LT |
176 | struct cfq_queue { |
177 | /* reference count */ | |
178 | atomic_t ref; | |
179 | /* parent cfq_data */ | |
180 | struct cfq_data *cfqd; | |
22e2c507 | 181 | /* cfqq lookup hash */ |
1da177e4 LT |
182 | struct hlist_node cfq_hash; |
183 | /* hash key */ | |
22e2c507 | 184 | unsigned int key; |
1da177e4 LT |
185 | /* on either rr or empty list of cfqd */ |
186 | struct list_head cfq_list; | |
187 | /* sorted list of pending requests */ | |
188 | struct rb_root sort_list; | |
189 | /* if fifo isn't expired, next request to serve */ | |
190 | struct cfq_rq *next_crq; | |
191 | /* requests queued in sort_list */ | |
192 | int queued[2]; | |
193 | /* currently allocated requests */ | |
194 | int allocated[2]; | |
195 | /* fifo list of requests in sort_list */ | |
22e2c507 | 196 | struct list_head fifo; |
1da177e4 | 197 | |
22e2c507 JA |
198 | unsigned long slice_start; |
199 | unsigned long slice_end; | |
200 | unsigned long slice_left; | |
201 | unsigned long service_last; | |
1da177e4 | 202 | |
3b18152c JA |
203 | /* number of requests that are on the dispatch list */ |
204 | int on_dispatch[2]; | |
22e2c507 JA |
205 | |
206 | /* io prio of this group */ | |
207 | unsigned short ioprio, org_ioprio; | |
208 | unsigned short ioprio_class, org_ioprio_class; | |
209 | ||
3b18152c JA |
210 | /* various state flags, see below */ |
211 | unsigned int flags; | |
1da177e4 LT |
212 | }; |
213 | ||
214 | struct cfq_rq { | |
215 | struct rb_node rb_node; | |
216 | sector_t rb_key; | |
217 | struct request *request; | |
218 | struct hlist_node hash; | |
219 | ||
220 | struct cfq_queue *cfq_queue; | |
221 | struct cfq_io_context *io_context; | |
222 | ||
3b18152c | 223 | unsigned int crq_flags; |
1da177e4 LT |
224 | }; |
225 | ||
3b18152c JA |
226 | enum cfqq_state_flags { |
227 | CFQ_CFQQ_FLAG_on_rr = 0, | |
228 | CFQ_CFQQ_FLAG_wait_request, | |
229 | CFQ_CFQQ_FLAG_must_alloc, | |
230 | CFQ_CFQQ_FLAG_must_alloc_slice, | |
231 | CFQ_CFQQ_FLAG_must_dispatch, | |
232 | CFQ_CFQQ_FLAG_fifo_expire, | |
233 | CFQ_CFQQ_FLAG_idle_window, | |
234 | CFQ_CFQQ_FLAG_prio_changed, | |
3b18152c JA |
235 | }; |
236 | ||
237 | #define CFQ_CFQQ_FNS(name) \ | |
238 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
239 | { \ | |
240 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
241 | } \ | |
242 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
243 | { \ | |
244 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
245 | } \ | |
246 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
247 | { \ | |
248 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
249 | } | |
250 | ||
251 | CFQ_CFQQ_FNS(on_rr); | |
252 | CFQ_CFQQ_FNS(wait_request); | |
253 | CFQ_CFQQ_FNS(must_alloc); | |
254 | CFQ_CFQQ_FNS(must_alloc_slice); | |
255 | CFQ_CFQQ_FNS(must_dispatch); | |
256 | CFQ_CFQQ_FNS(fifo_expire); | |
257 | CFQ_CFQQ_FNS(idle_window); | |
258 | CFQ_CFQQ_FNS(prio_changed); | |
3b18152c JA |
259 | #undef CFQ_CFQQ_FNS |
260 | ||
261 | enum cfq_rq_state_flags { | |
b4878f24 | 262 | CFQ_CRQ_FLAG_is_sync = 0, |
3b18152c JA |
263 | }; |
264 | ||
265 | #define CFQ_CRQ_FNS(name) \ | |
266 | static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ | |
267 | { \ | |
268 | crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ | |
269 | } \ | |
270 | static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ | |
271 | { \ | |
272 | crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ | |
273 | } \ | |
274 | static inline int cfq_crq_##name(const struct cfq_rq *crq) \ | |
275 | { \ | |
276 | return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ | |
277 | } | |
278 | ||
3b18152c | 279 | CFQ_CRQ_FNS(is_sync); |
3b18152c JA |
280 | #undef CFQ_CRQ_FNS |
281 | ||
282 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); | |
b4878f24 | 283 | static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); |
6f325a13 | 284 | static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); |
1da177e4 | 285 | |
22e2c507 | 286 | #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) |
1da177e4 LT |
287 | |
288 | /* | |
289 | * lots of deadline iosched dupes, can be abstracted later... | |
290 | */ | |
291 | static inline void cfq_del_crq_hash(struct cfq_rq *crq) | |
292 | { | |
293 | hlist_del_init(&crq->hash); | |
294 | } | |
295 | ||
1da177e4 LT |
296 | static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) |
297 | { | |
298 | const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); | |
299 | ||
1da177e4 LT |
300 | hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); |
301 | } | |
302 | ||
303 | static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) | |
304 | { | |
305 | struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; | |
306 | struct hlist_node *entry, *next; | |
307 | ||
308 | hlist_for_each_safe(entry, next, hash_list) { | |
309 | struct cfq_rq *crq = list_entry_hash(entry); | |
310 | struct request *__rq = crq->request; | |
311 | ||
1da177e4 LT |
312 | if (!rq_mergeable(__rq)) { |
313 | cfq_del_crq_hash(crq); | |
314 | continue; | |
315 | } | |
316 | ||
317 | if (rq_hash_key(__rq) == offset) | |
318 | return __rq; | |
319 | } | |
320 | ||
321 | return NULL; | |
322 | } | |
323 | ||
99f95e52 AM |
324 | /* |
325 | * scheduler run of queue, if there are requests pending and no one in the | |
326 | * driver that will restart queueing | |
327 | */ | |
328 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
329 | { | |
7b14e3b5 | 330 | if (cfqd->busy_queues) |
99f95e52 AM |
331 | kblockd_schedule_work(&cfqd->unplug_work); |
332 | } | |
333 | ||
334 | static int cfq_queue_empty(request_queue_t *q) | |
335 | { | |
336 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
337 | ||
b4878f24 | 338 | return !cfqd->busy_queues; |
99f95e52 AM |
339 | } |
340 | ||
206dc69b JA |
341 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) |
342 | { | |
343 | if (rw == READ || process_sync(task)) | |
344 | return task->pid; | |
345 | ||
346 | return CFQ_KEY_ASYNC; | |
347 | } | |
348 | ||
1da177e4 LT |
349 | /* |
350 | * Lifted from AS - choose which of crq1 and crq2 that is best served now. | |
351 | * We choose the request that is closest to the head right now. Distance | |
e8a99053 | 352 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 LT |
353 | */ |
354 | static struct cfq_rq * | |
355 | cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) | |
356 | { | |
357 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 358 | unsigned long back_max; |
e8a99053 AM |
359 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
360 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
361 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 LT |
362 | |
363 | if (crq1 == NULL || crq1 == crq2) | |
364 | return crq2; | |
365 | if (crq2 == NULL) | |
366 | return crq1; | |
9c2c38a1 | 367 | |
9c2c38a1 JA |
368 | if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) |
369 | return crq1; | |
370 | else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) | |
22e2c507 | 371 | return crq2; |
1da177e4 LT |
372 | |
373 | s1 = crq1->request->sector; | |
374 | s2 = crq2->request->sector; | |
375 | ||
376 | last = cfqd->last_sector; | |
377 | ||
1da177e4 LT |
378 | /* |
379 | * by definition, 1KiB is 2 sectors | |
380 | */ | |
381 | back_max = cfqd->cfq_back_max * 2; | |
382 | ||
383 | /* | |
384 | * Strict one way elevator _except_ in the case where we allow | |
385 | * short backward seeks which are biased as twice the cost of a | |
386 | * similar forward seek. | |
387 | */ | |
388 | if (s1 >= last) | |
389 | d1 = s1 - last; | |
390 | else if (s1 + back_max >= last) | |
391 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
392 | else | |
e8a99053 | 393 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
394 | |
395 | if (s2 >= last) | |
396 | d2 = s2 - last; | |
397 | else if (s2 + back_max >= last) | |
398 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
399 | else | |
e8a99053 | 400 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
401 | |
402 | /* Found required data */ | |
e8a99053 AM |
403 | |
404 | /* | |
405 | * By doing switch() on the bit mask "wrap" we avoid having to | |
406 | * check two variables for all permutations: --> faster! | |
407 | */ | |
408 | switch (wrap) { | |
409 | case 0: /* common case for CFQ: crq1 and crq2 not wrapped */ | |
410 | if (d1 < d2) | |
1da177e4 | 411 | return crq1; |
e8a99053 | 412 | else if (d2 < d1) |
1da177e4 | 413 | return crq2; |
e8a99053 AM |
414 | else { |
415 | if (s1 >= s2) | |
416 | return crq1; | |
417 | else | |
418 | return crq2; | |
419 | } | |
1da177e4 | 420 | |
e8a99053 | 421 | case CFQ_RQ2_WRAP: |
1da177e4 | 422 | return crq1; |
e8a99053 | 423 | case CFQ_RQ1_WRAP: |
1da177e4 | 424 | return crq2; |
e8a99053 AM |
425 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both crqs wrapped */ |
426 | default: | |
427 | /* | |
428 | * Since both rqs are wrapped, | |
429 | * start with the one that's further behind head | |
430 | * (--> only *one* back seek required), | |
431 | * since back seek takes more time than forward. | |
432 | */ | |
433 | if (s1 <= s2) | |
1da177e4 LT |
434 | return crq1; |
435 | else | |
436 | return crq2; | |
437 | } | |
438 | } | |
439 | ||
440 | /* | |
441 | * would be nice to take fifo expire time into account as well | |
442 | */ | |
443 | static struct cfq_rq * | |
444 | cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
445 | struct cfq_rq *last) | |
446 | { | |
447 | struct cfq_rq *crq_next = NULL, *crq_prev = NULL; | |
448 | struct rb_node *rbnext, *rbprev; | |
449 | ||
b4878f24 | 450 | if (!(rbnext = rb_next(&last->rb_node))) { |
1da177e4 | 451 | rbnext = rb_first(&cfqq->sort_list); |
22e2c507 JA |
452 | if (rbnext == &last->rb_node) |
453 | rbnext = NULL; | |
454 | } | |
1da177e4 LT |
455 | |
456 | rbprev = rb_prev(&last->rb_node); | |
457 | ||
458 | if (rbprev) | |
459 | crq_prev = rb_entry_crq(rbprev); | |
460 | if (rbnext) | |
461 | crq_next = rb_entry_crq(rbnext); | |
462 | ||
463 | return cfq_choose_req(cfqd, crq_next, crq_prev); | |
464 | } | |
465 | ||
466 | static void cfq_update_next_crq(struct cfq_rq *crq) | |
467 | { | |
468 | struct cfq_queue *cfqq = crq->cfq_queue; | |
469 | ||
470 | if (cfqq->next_crq == crq) | |
471 | cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); | |
472 | } | |
473 | ||
22e2c507 | 474 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
1da177e4 | 475 | { |
22e2c507 JA |
476 | struct cfq_data *cfqd = cfqq->cfqd; |
477 | struct list_head *list, *entry; | |
1da177e4 | 478 | |
3b18152c | 479 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 480 | |
22e2c507 | 481 | list_del(&cfqq->cfq_list); |
1da177e4 | 482 | |
22e2c507 JA |
483 | if (cfq_class_rt(cfqq)) |
484 | list = &cfqd->cur_rr; | |
485 | else if (cfq_class_idle(cfqq)) | |
486 | list = &cfqd->idle_rr; | |
487 | else { | |
488 | /* | |
489 | * if cfqq has requests in flight, don't allow it to be | |
490 | * found in cfq_set_active_queue before it has finished them. | |
491 | * this is done to increase fairness between a process that | |
492 | * has lots of io pending vs one that only generates one | |
493 | * sporadically or synchronously | |
494 | */ | |
3b18152c | 495 | if (cfq_cfqq_dispatched(cfqq)) |
22e2c507 JA |
496 | list = &cfqd->busy_rr; |
497 | else | |
498 | list = &cfqd->rr_list[cfqq->ioprio]; | |
1da177e4 LT |
499 | } |
500 | ||
22e2c507 JA |
501 | /* |
502 | * if queue was preempted, just add to front to be fair. busy_rr | |
503 | * isn't sorted. | |
504 | */ | |
505 | if (preempted || list == &cfqd->busy_rr) { | |
506 | list_add(&cfqq->cfq_list, list); | |
1da177e4 | 507 | return; |
22e2c507 | 508 | } |
1da177e4 LT |
509 | |
510 | /* | |
22e2c507 | 511 | * sort by when queue was last serviced |
1da177e4 | 512 | */ |
22e2c507 JA |
513 | entry = list; |
514 | while ((entry = entry->prev) != list) { | |
1da177e4 LT |
515 | struct cfq_queue *__cfqq = list_entry_cfqq(entry); |
516 | ||
22e2c507 JA |
517 | if (!__cfqq->service_last) |
518 | break; | |
519 | if (time_before(__cfqq->service_last, cfqq->service_last)) | |
1da177e4 | 520 | break; |
1da177e4 LT |
521 | } |
522 | ||
523 | list_add(&cfqq->cfq_list, entry); | |
524 | } | |
525 | ||
526 | /* | |
527 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 528 | * the pending list according to last request service |
1da177e4 LT |
529 | */ |
530 | static inline void | |
b4878f24 | 531 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 532 | { |
3b18152c JA |
533 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
534 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
535 | cfqd->busy_queues++; |
536 | ||
b4878f24 | 537 | cfq_resort_rr_list(cfqq, 0); |
1da177e4 LT |
538 | } |
539 | ||
540 | static inline void | |
541 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
542 | { | |
3b18152c JA |
543 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
544 | cfq_clear_cfqq_on_rr(cfqq); | |
22e2c507 | 545 | list_move(&cfqq->cfq_list, &cfqd->empty_list); |
1da177e4 LT |
546 | |
547 | BUG_ON(!cfqd->busy_queues); | |
548 | cfqd->busy_queues--; | |
549 | } | |
550 | ||
551 | /* | |
552 | * rb tree support functions | |
553 | */ | |
554 | static inline void cfq_del_crq_rb(struct cfq_rq *crq) | |
555 | { | |
556 | struct cfq_queue *cfqq = crq->cfq_queue; | |
b4878f24 JA |
557 | struct cfq_data *cfqd = cfqq->cfqd; |
558 | const int sync = cfq_crq_is_sync(crq); | |
1da177e4 | 559 | |
b4878f24 JA |
560 | BUG_ON(!cfqq->queued[sync]); |
561 | cfqq->queued[sync]--; | |
1da177e4 | 562 | |
b4878f24 | 563 | cfq_update_next_crq(crq); |
1da177e4 | 564 | |
b4878f24 JA |
565 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
566 | RB_CLEAR_COLOR(&crq->rb_node); | |
1da177e4 | 567 | |
b4878f24 JA |
568 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list)) |
569 | cfq_del_cfqq_rr(cfqd, cfqq); | |
1da177e4 LT |
570 | } |
571 | ||
572 | static struct cfq_rq * | |
573 | __cfq_add_crq_rb(struct cfq_rq *crq) | |
574 | { | |
575 | struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; | |
576 | struct rb_node *parent = NULL; | |
577 | struct cfq_rq *__crq; | |
578 | ||
579 | while (*p) { | |
580 | parent = *p; | |
581 | __crq = rb_entry_crq(parent); | |
582 | ||
583 | if (crq->rb_key < __crq->rb_key) | |
584 | p = &(*p)->rb_left; | |
585 | else if (crq->rb_key > __crq->rb_key) | |
586 | p = &(*p)->rb_right; | |
587 | else | |
588 | return __crq; | |
589 | } | |
590 | ||
591 | rb_link_node(&crq->rb_node, parent, p); | |
592 | return NULL; | |
593 | } | |
594 | ||
595 | static void cfq_add_crq_rb(struct cfq_rq *crq) | |
596 | { | |
597 | struct cfq_queue *cfqq = crq->cfq_queue; | |
598 | struct cfq_data *cfqd = cfqq->cfqd; | |
599 | struct request *rq = crq->request; | |
600 | struct cfq_rq *__alias; | |
601 | ||
602 | crq->rb_key = rq_rb_key(rq); | |
3b18152c | 603 | cfqq->queued[cfq_crq_is_sync(crq)]++; |
1da177e4 LT |
604 | |
605 | /* | |
606 | * looks a little odd, but the first insert might return an alias. | |
607 | * if that happens, put the alias on the dispatch list | |
608 | */ | |
609 | while ((__alias = __cfq_add_crq_rb(crq)) != NULL) | |
b4878f24 | 610 | cfq_dispatch_insert(cfqd->queue, __alias); |
1da177e4 LT |
611 | |
612 | rb_insert_color(&crq->rb_node, &cfqq->sort_list); | |
613 | ||
3b18152c | 614 | if (!cfq_cfqq_on_rr(cfqq)) |
b4878f24 | 615 | cfq_add_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
616 | |
617 | /* | |
618 | * check if this request is a better next-serve candidate | |
619 | */ | |
620 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
621 | } | |
622 | ||
623 | static inline void | |
624 | cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
625 | { | |
b4878f24 JA |
626 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
627 | cfqq->queued[cfq_crq_is_sync(crq)]--; | |
1da177e4 LT |
628 | |
629 | cfq_add_crq_rb(crq); | |
630 | } | |
631 | ||
206dc69b JA |
632 | static struct request * |
633 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 634 | { |
206dc69b JA |
635 | struct task_struct *tsk = current; |
636 | pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio)); | |
637 | struct cfq_queue *cfqq; | |
1da177e4 | 638 | struct rb_node *n; |
206dc69b | 639 | sector_t sector; |
1da177e4 | 640 | |
206dc69b | 641 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); |
1da177e4 LT |
642 | if (!cfqq) |
643 | goto out; | |
644 | ||
206dc69b | 645 | sector = bio->bi_sector + bio_sectors(bio); |
1da177e4 LT |
646 | n = cfqq->sort_list.rb_node; |
647 | while (n) { | |
648 | struct cfq_rq *crq = rb_entry_crq(n); | |
649 | ||
650 | if (sector < crq->rb_key) | |
651 | n = n->rb_left; | |
652 | else if (sector > crq->rb_key) | |
653 | n = n->rb_right; | |
654 | else | |
655 | return crq->request; | |
656 | } | |
657 | ||
658 | out: | |
659 | return NULL; | |
660 | } | |
661 | ||
b4878f24 | 662 | static void cfq_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 663 | { |
22e2c507 | 664 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 665 | |
b4878f24 | 666 | cfqd->rq_in_driver++; |
1da177e4 LT |
667 | } |
668 | ||
b4878f24 | 669 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 670 | { |
b4878f24 JA |
671 | struct cfq_data *cfqd = q->elevator->elevator_data; |
672 | ||
673 | WARN_ON(!cfqd->rq_in_driver); | |
674 | cfqd->rq_in_driver--; | |
1da177e4 LT |
675 | } |
676 | ||
b4878f24 | 677 | static void cfq_remove_request(struct request *rq) |
1da177e4 LT |
678 | { |
679 | struct cfq_rq *crq = RQ_DATA(rq); | |
680 | ||
b4878f24 JA |
681 | list_del_init(&rq->queuelist); |
682 | cfq_del_crq_rb(crq); | |
98b11471 | 683 | cfq_del_crq_hash(crq); |
1da177e4 LT |
684 | } |
685 | ||
686 | static int | |
687 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
688 | { | |
689 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
690 | struct request *__rq; | |
691 | int ret; | |
692 | ||
1da177e4 | 693 | __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); |
22e2c507 JA |
694 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
695 | ret = ELEVATOR_BACK_MERGE; | |
696 | goto out; | |
1da177e4 LT |
697 | } |
698 | ||
206dc69b | 699 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 JA |
700 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
701 | ret = ELEVATOR_FRONT_MERGE; | |
702 | goto out; | |
1da177e4 LT |
703 | } |
704 | ||
705 | return ELEVATOR_NO_MERGE; | |
706 | out: | |
1da177e4 LT |
707 | *req = __rq; |
708 | return ret; | |
709 | } | |
710 | ||
711 | static void cfq_merged_request(request_queue_t *q, struct request *req) | |
712 | { | |
713 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
714 | struct cfq_rq *crq = RQ_DATA(req); | |
715 | ||
716 | cfq_del_crq_hash(crq); | |
717 | cfq_add_crq_hash(cfqd, crq); | |
718 | ||
b4878f24 | 719 | if (rq_rb_key(req) != crq->rb_key) { |
1da177e4 LT |
720 | struct cfq_queue *cfqq = crq->cfq_queue; |
721 | ||
722 | cfq_update_next_crq(crq); | |
723 | cfq_reposition_crq_rb(cfqq, crq); | |
724 | } | |
1da177e4 LT |
725 | } |
726 | ||
727 | static void | |
728 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
729 | struct request *next) | |
730 | { | |
1da177e4 LT |
731 | cfq_merged_request(q, rq); |
732 | ||
22e2c507 JA |
733 | /* |
734 | * reposition in fifo if next is older than rq | |
735 | */ | |
736 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
737 | time_before(next->start_time, rq->start_time)) | |
738 | list_move(&rq->queuelist, &next->queuelist); | |
739 | ||
b4878f24 | 740 | cfq_remove_request(next); |
22e2c507 JA |
741 | } |
742 | ||
743 | static inline void | |
744 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
745 | { | |
746 | if (cfqq) { | |
747 | /* | |
748 | * stop potential idle class queues waiting service | |
749 | */ | |
750 | del_timer(&cfqd->idle_class_timer); | |
751 | ||
752 | cfqq->slice_start = jiffies; | |
753 | cfqq->slice_end = 0; | |
754 | cfqq->slice_left = 0; | |
3b18152c JA |
755 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
756 | cfq_clear_cfqq_fifo_expire(cfqq); | |
22e2c507 JA |
757 | } |
758 | ||
759 | cfqd->active_queue = cfqq; | |
760 | } | |
761 | ||
7b14e3b5 JA |
762 | /* |
763 | * current cfqq expired its slice (or was too idle), select new one | |
764 | */ | |
765 | static void | |
766 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
767 | int preempted) | |
768 | { | |
769 | unsigned long now = jiffies; | |
770 | ||
771 | if (cfq_cfqq_wait_request(cfqq)) | |
772 | del_timer(&cfqd->idle_slice_timer); | |
773 | ||
774 | if (!preempted && !cfq_cfqq_dispatched(cfqq)) { | |
775 | cfqq->service_last = now; | |
776 | cfq_schedule_dispatch(cfqd); | |
777 | } | |
778 | ||
779 | cfq_clear_cfqq_must_dispatch(cfqq); | |
780 | cfq_clear_cfqq_wait_request(cfqq); | |
781 | ||
782 | /* | |
783 | * store what was left of this slice, if the queue idled out | |
784 | * or was preempted | |
785 | */ | |
786 | if (time_after(cfqq->slice_end, now)) | |
787 | cfqq->slice_left = cfqq->slice_end - now; | |
788 | else | |
789 | cfqq->slice_left = 0; | |
790 | ||
791 | if (cfq_cfqq_on_rr(cfqq)) | |
792 | cfq_resort_rr_list(cfqq, preempted); | |
793 | ||
794 | if (cfqq == cfqd->active_queue) | |
795 | cfqd->active_queue = NULL; | |
796 | ||
797 | if (cfqd->active_cic) { | |
798 | put_io_context(cfqd->active_cic->ioc); | |
799 | cfqd->active_cic = NULL; | |
800 | } | |
801 | ||
802 | cfqd->dispatch_slice = 0; | |
803 | } | |
804 | ||
805 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
806 | { | |
807 | struct cfq_queue *cfqq = cfqd->active_queue; | |
808 | ||
809 | if (cfqq) | |
810 | __cfq_slice_expired(cfqd, cfqq, preempted); | |
811 | } | |
812 | ||
22e2c507 JA |
813 | /* |
814 | * 0 | |
815 | * 0,1 | |
816 | * 0,1,2 | |
817 | * 0,1,2,3 | |
818 | * 0,1,2,3,4 | |
819 | * 0,1,2,3,4,5 | |
820 | * 0,1,2,3,4,5,6 | |
821 | * 0,1,2,3,4,5,6,7 | |
822 | */ | |
823 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
824 | { | |
825 | int prio, wrap; | |
826 | ||
827 | prio = -1; | |
828 | wrap = 0; | |
829 | do { | |
830 | int p; | |
831 | ||
832 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
833 | if (!list_empty(&cfqd->rr_list[p])) { | |
834 | prio = p; | |
835 | break; | |
836 | } | |
837 | } | |
838 | ||
839 | if (prio != -1) | |
840 | break; | |
841 | cfqd->cur_prio = 0; | |
842 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
843 | cfqd->cur_end_prio = 0; | |
844 | if (wrap) | |
845 | break; | |
846 | wrap = 1; | |
1da177e4 | 847 | } |
22e2c507 JA |
848 | } while (1); |
849 | ||
850 | if (unlikely(prio == -1)) | |
851 | return -1; | |
852 | ||
853 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
854 | ||
855 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
856 | ||
857 | cfqd->cur_prio = prio + 1; | |
858 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
859 | cfqd->cur_end_prio = cfqd->cur_prio; | |
860 | cfqd->cur_prio = 0; | |
861 | } | |
862 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
863 | cfqd->cur_prio = 0; | |
864 | cfqd->cur_end_prio = 0; | |
1da177e4 LT |
865 | } |
866 | ||
22e2c507 JA |
867 | return prio; |
868 | } | |
869 | ||
3b18152c | 870 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
22e2c507 | 871 | { |
7b14e3b5 | 872 | struct cfq_queue *cfqq = NULL; |
22e2c507 JA |
873 | |
874 | /* | |
875 | * if current list is non-empty, grab first entry. if it is empty, | |
876 | * get next prio level and grab first entry then if any are spliced | |
877 | */ | |
878 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) | |
879 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
880 | ||
881 | /* | |
882 | * if we have idle queues and no rt or be queues had pending | |
883 | * requests, either allow immediate service if the grace period | |
884 | * has passed or arm the idle grace timer | |
885 | */ | |
886 | if (!cfqq && !list_empty(&cfqd->idle_rr)) { | |
887 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
888 | ||
889 | if (time_after_eq(jiffies, end)) | |
890 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
891 | else | |
892 | mod_timer(&cfqd->idle_class_timer, end); | |
893 | } | |
894 | ||
895 | __cfq_set_active_queue(cfqd, cfqq); | |
3b18152c | 896 | return cfqq; |
22e2c507 JA |
897 | } |
898 | ||
22e2c507 JA |
899 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
900 | ||
901 | { | |
206dc69b | 902 | struct cfq_io_context *cic; |
7b14e3b5 JA |
903 | unsigned long sl; |
904 | ||
22e2c507 JA |
905 | WARN_ON(!RB_EMPTY(&cfqq->sort_list)); |
906 | WARN_ON(cfqq != cfqd->active_queue); | |
907 | ||
908 | /* | |
909 | * idle is disabled, either manually or by past process history | |
910 | */ | |
911 | if (!cfqd->cfq_slice_idle) | |
912 | return 0; | |
3b18152c | 913 | if (!cfq_cfqq_idle_window(cfqq)) |
22e2c507 JA |
914 | return 0; |
915 | /* | |
916 | * task has exited, don't wait | |
917 | */ | |
206dc69b JA |
918 | cic = cfqd->active_cic; |
919 | if (!cic || !cic->ioc->task) | |
22e2c507 JA |
920 | return 0; |
921 | ||
3b18152c JA |
922 | cfq_mark_cfqq_must_dispatch(cfqq); |
923 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 924 | |
7b14e3b5 | 925 | sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); |
206dc69b JA |
926 | |
927 | /* | |
928 | * we don't want to idle for seeks, but we do want to allow | |
929 | * fair distribution of slice time for a process doing back-to-back | |
930 | * seeks. so allow a little bit of time for him to submit a new rq | |
931 | */ | |
932 | if (sample_valid(cic->seek_samples) && cic->seek_mean > 131072) | |
933 | sl = 2; | |
934 | ||
7b14e3b5 | 935 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
22e2c507 | 936 | return 1; |
1da177e4 LT |
937 | } |
938 | ||
b4878f24 | 939 | static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) |
1da177e4 LT |
940 | { |
941 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
942 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 JA |
943 | |
944 | cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); | |
b4878f24 | 945 | cfq_remove_request(crq->request); |
3b18152c | 946 | cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; |
b4878f24 | 947 | elv_dispatch_sort(q, crq->request); |
1da177e4 LT |
948 | } |
949 | ||
950 | /* | |
951 | * return expired entry, or NULL to just start from scratch in rbtree | |
952 | */ | |
953 | static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) | |
954 | { | |
955 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 956 | struct request *rq; |
1da177e4 LT |
957 | struct cfq_rq *crq; |
958 | ||
3b18152c | 959 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 LT |
960 | return NULL; |
961 | ||
22e2c507 | 962 | if (!list_empty(&cfqq->fifo)) { |
3b18152c | 963 | int fifo = cfq_cfqq_class_sync(cfqq); |
1da177e4 | 964 | |
22e2c507 JA |
965 | crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); |
966 | rq = crq->request; | |
967 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
3b18152c | 968 | cfq_mark_cfqq_fifo_expire(cfqq); |
22e2c507 JA |
969 | return crq; |
970 | } | |
1da177e4 LT |
971 | } |
972 | ||
973 | return NULL; | |
974 | } | |
975 | ||
976 | /* | |
3b18152c JA |
977 | * Scale schedule slice based on io priority. Use the sync time slice only |
978 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
979 | * io only, should not get full sync slice length. | |
1da177e4 | 980 | */ |
22e2c507 JA |
981 | static inline int |
982 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
983 | { | |
984 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
985 | ||
986 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
987 | ||
988 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
989 | } | |
990 | ||
1da177e4 | 991 | static inline void |
22e2c507 | 992 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 993 | { |
22e2c507 JA |
994 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
995 | } | |
1da177e4 | 996 | |
22e2c507 JA |
997 | static inline int |
998 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
999 | { | |
1000 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1001 | |
22e2c507 | 1002 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1003 | |
22e2c507 | 1004 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1005 | } |
1006 | ||
22e2c507 JA |
1007 | /* |
1008 | * get next queue for service | |
1009 | */ | |
1b5ed5e1 | 1010 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1011 | { |
22e2c507 | 1012 | unsigned long now = jiffies; |
1da177e4 | 1013 | struct cfq_queue *cfqq; |
1da177e4 | 1014 | |
22e2c507 JA |
1015 | cfqq = cfqd->active_queue; |
1016 | if (!cfqq) | |
1017 | goto new_queue; | |
1da177e4 | 1018 | |
22e2c507 JA |
1019 | /* |
1020 | * slice has expired | |
1021 | */ | |
3b18152c JA |
1022 | if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) |
1023 | goto expire; | |
1da177e4 | 1024 | |
22e2c507 JA |
1025 | /* |
1026 | * if queue has requests, dispatch one. if not, check if | |
1027 | * enough slice is left to wait for one | |
1028 | */ | |
1029 | if (!RB_EMPTY(&cfqq->sort_list)) | |
1030 | goto keep_queue; | |
1b5ed5e1 | 1031 | else if (cfq_cfqq_class_sync(cfqq) && |
22e2c507 JA |
1032 | time_before(now, cfqq->slice_end)) { |
1033 | if (cfq_arm_slice_timer(cfqd, cfqq)) | |
1034 | return NULL; | |
1035 | } | |
1036 | ||
3b18152c | 1037 | expire: |
22e2c507 | 1038 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
1039 | new_queue: |
1040 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 1041 | keep_queue: |
3b18152c | 1042 | return cfqq; |
22e2c507 JA |
1043 | } |
1044 | ||
1045 | static int | |
1046 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1047 | int max_dispatch) | |
1048 | { | |
1049 | int dispatched = 0; | |
1050 | ||
1051 | BUG_ON(RB_EMPTY(&cfqq->sort_list)); | |
1052 | ||
1053 | do { | |
1054 | struct cfq_rq *crq; | |
1da177e4 LT |
1055 | |
1056 | /* | |
22e2c507 | 1057 | * follow expired path, else get first next available |
1da177e4 | 1058 | */ |
22e2c507 JA |
1059 | if ((crq = cfq_check_fifo(cfqq)) == NULL) |
1060 | crq = cfqq->next_crq; | |
1061 | ||
1062 | /* | |
1063 | * finally, insert request into driver dispatch list | |
1064 | */ | |
b4878f24 | 1065 | cfq_dispatch_insert(cfqd->queue, crq); |
1da177e4 | 1066 | |
22e2c507 JA |
1067 | cfqd->dispatch_slice++; |
1068 | dispatched++; | |
1da177e4 | 1069 | |
22e2c507 JA |
1070 | if (!cfqd->active_cic) { |
1071 | atomic_inc(&crq->io_context->ioc->refcount); | |
1072 | cfqd->active_cic = crq->io_context; | |
1073 | } | |
1da177e4 | 1074 | |
22e2c507 JA |
1075 | if (RB_EMPTY(&cfqq->sort_list)) |
1076 | break; | |
1077 | ||
1078 | } while (dispatched < max_dispatch); | |
1079 | ||
1080 | /* | |
1081 | * if slice end isn't set yet, set it. if at least one request was | |
1082 | * sync, use the sync time slice value | |
1083 | */ | |
1084 | if (!cfqq->slice_end) | |
1085 | cfq_set_prio_slice(cfqd, cfqq); | |
1086 | ||
1087 | /* | |
1088 | * expire an async queue immediately if it has used up its slice. idle | |
1089 | * queue always expire after 1 dispatch round. | |
1090 | */ | |
1091 | if ((!cfq_cfqq_sync(cfqq) && | |
1092 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1093 | cfq_class_idle(cfqq)) | |
1094 | cfq_slice_expired(cfqd, 0); | |
1095 | ||
1096 | return dispatched; | |
1097 | } | |
1098 | ||
1b5ed5e1 TH |
1099 | static int |
1100 | cfq_forced_dispatch_cfqqs(struct list_head *list) | |
1101 | { | |
1102 | int dispatched = 0; | |
1103 | struct cfq_queue *cfqq, *next; | |
1104 | struct cfq_rq *crq; | |
1105 | ||
1106 | list_for_each_entry_safe(cfqq, next, list, cfq_list) { | |
1107 | while ((crq = cfqq->next_crq)) { | |
1108 | cfq_dispatch_insert(cfqq->cfqd->queue, crq); | |
1109 | dispatched++; | |
1110 | } | |
1111 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1112 | } | |
1113 | return dispatched; | |
1114 | } | |
1115 | ||
1116 | static int | |
1117 | cfq_forced_dispatch(struct cfq_data *cfqd) | |
1118 | { | |
1119 | int i, dispatched = 0; | |
1120 | ||
1121 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
1122 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]); | |
1123 | ||
1124 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr); | |
1125 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); | |
1126 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
1127 | ||
1128 | cfq_slice_expired(cfqd, 0); | |
1129 | ||
1130 | BUG_ON(cfqd->busy_queues); | |
1131 | ||
1132 | return dispatched; | |
1133 | } | |
1134 | ||
22e2c507 | 1135 | static int |
b4878f24 | 1136 | cfq_dispatch_requests(request_queue_t *q, int force) |
22e2c507 JA |
1137 | { |
1138 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1139 | struct cfq_queue *cfqq; | |
1140 | ||
1141 | if (!cfqd->busy_queues) | |
1142 | return 0; | |
1143 | ||
1b5ed5e1 TH |
1144 | if (unlikely(force)) |
1145 | return cfq_forced_dispatch(cfqd); | |
1146 | ||
1147 | cfqq = cfq_select_queue(cfqd); | |
22e2c507 | 1148 | if (cfqq) { |
b4878f24 JA |
1149 | int max_dispatch; |
1150 | ||
3b18152c JA |
1151 | cfq_clear_cfqq_must_dispatch(cfqq); |
1152 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1153 | del_timer(&cfqd->idle_slice_timer); |
1154 | ||
1b5ed5e1 TH |
1155 | max_dispatch = cfqd->cfq_quantum; |
1156 | if (cfq_class_idle(cfqq)) | |
1157 | max_dispatch = 1; | |
1da177e4 | 1158 | |
22e2c507 | 1159 | return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1160 | } |
1161 | ||
22e2c507 | 1162 | return 0; |
1da177e4 LT |
1163 | } |
1164 | ||
1da177e4 LT |
1165 | /* |
1166 | * task holds one reference to the queue, dropped when task exits. each crq | |
1167 | * in-flight on this queue also holds a reference, dropped when crq is freed. | |
1168 | * | |
1169 | * queue lock must be held here. | |
1170 | */ | |
1171 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1172 | { | |
22e2c507 JA |
1173 | struct cfq_data *cfqd = cfqq->cfqd; |
1174 | ||
1175 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1176 | |
1177 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1178 | return; | |
1179 | ||
1180 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1181 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1182 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1183 | |
7b14e3b5 | 1184 | if (unlikely(cfqd->active_queue == cfqq)) |
3b18152c | 1185 | __cfq_slice_expired(cfqd, cfqq, 0); |
22e2c507 | 1186 | |
1da177e4 LT |
1187 | /* |
1188 | * it's on the empty list and still hashed | |
1189 | */ | |
1190 | list_del(&cfqq->cfq_list); | |
1191 | hlist_del(&cfqq->cfq_hash); | |
1192 | kmem_cache_free(cfq_pool, cfqq); | |
1193 | } | |
1194 | ||
1195 | static inline struct cfq_queue * | |
3b18152c JA |
1196 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, |
1197 | const int hashval) | |
1da177e4 LT |
1198 | { |
1199 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
206dc69b JA |
1200 | struct hlist_node *entry; |
1201 | struct cfq_queue *__cfqq; | |
1da177e4 | 1202 | |
206dc69b | 1203 | hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) { |
b0a6916b | 1204 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); |
1da177e4 | 1205 | |
206dc69b | 1206 | if (__cfqq->key == key && (__p == prio || !prio)) |
1da177e4 LT |
1207 | return __cfqq; |
1208 | } | |
1209 | ||
1210 | return NULL; | |
1211 | } | |
1212 | ||
1213 | static struct cfq_queue * | |
3b18152c | 1214 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) |
1da177e4 | 1215 | { |
3b18152c | 1216 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); |
1da177e4 LT |
1217 | } |
1218 | ||
e2d74ac0 | 1219 | static void cfq_free_io_context(struct io_context *ioc) |
1da177e4 | 1220 | { |
22e2c507 | 1221 | struct cfq_io_context *__cic; |
e2d74ac0 JA |
1222 | struct rb_node *n; |
1223 | int freed = 0; | |
1da177e4 | 1224 | |
e2d74ac0 JA |
1225 | while ((n = rb_first(&ioc->cic_root)) != NULL) { |
1226 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1227 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
22e2c507 | 1228 | kmem_cache_free(cfq_ioc_pool, __cic); |
334e94de | 1229 | freed++; |
1da177e4 LT |
1230 | } |
1231 | ||
334e94de AV |
1232 | if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone) |
1233 | complete(ioc_gone); | |
1da177e4 LT |
1234 | } |
1235 | ||
e17a9489 AV |
1236 | static void cfq_trim(struct io_context *ioc) |
1237 | { | |
1238 | ioc->set_ioprio = NULL; | |
e2d74ac0 | 1239 | cfq_free_io_context(ioc); |
e17a9489 AV |
1240 | } |
1241 | ||
22e2c507 JA |
1242 | /* |
1243 | * Called with interrupts disabled | |
1244 | */ | |
1245 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1da177e4 | 1246 | { |
478a82b0 | 1247 | struct cfq_data *cfqd = cic->key; |
d9ff4187 AV |
1248 | request_queue_t *q; |
1249 | ||
1250 | if (!cfqd) | |
1251 | return; | |
1252 | ||
1253 | q = cfqd->queue; | |
22e2c507 JA |
1254 | |
1255 | WARN_ON(!irqs_disabled()); | |
1256 | ||
1257 | spin_lock(q->queue_lock); | |
1258 | ||
12a05732 AV |
1259 | if (cic->cfqq[ASYNC]) { |
1260 | if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue)) | |
1261 | __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0); | |
1262 | cfq_put_queue(cic->cfqq[ASYNC]); | |
1263 | cic->cfqq[ASYNC] = NULL; | |
1264 | } | |
1265 | ||
1266 | if (cic->cfqq[SYNC]) { | |
1267 | if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue)) | |
1268 | __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0); | |
1269 | cfq_put_queue(cic->cfqq[SYNC]); | |
1270 | cic->cfqq[SYNC] = NULL; | |
1271 | } | |
22e2c507 | 1272 | |
478a82b0 | 1273 | cic->key = NULL; |
d9ff4187 | 1274 | list_del_init(&cic->queue_list); |
22e2c507 | 1275 | spin_unlock(q->queue_lock); |
1da177e4 LT |
1276 | } |
1277 | ||
e2d74ac0 | 1278 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1279 | { |
22e2c507 | 1280 | struct cfq_io_context *__cic; |
1da177e4 | 1281 | unsigned long flags; |
e2d74ac0 | 1282 | struct rb_node *n; |
22e2c507 | 1283 | |
1da177e4 LT |
1284 | /* |
1285 | * put the reference this task is holding to the various queues | |
1286 | */ | |
e2d74ac0 JA |
1287 | read_lock_irqsave(&cfq_exit_lock, flags); |
1288 | ||
1289 | n = rb_first(&ioc->cic_root); | |
1290 | while (n != NULL) { | |
1291 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1292 | ||
22e2c507 | 1293 | cfq_exit_single_io_context(__cic); |
e2d74ac0 | 1294 | n = rb_next(n); |
1da177e4 LT |
1295 | } |
1296 | ||
e2d74ac0 | 1297 | read_unlock_irqrestore(&cfq_exit_lock, flags); |
1da177e4 LT |
1298 | } |
1299 | ||
22e2c507 | 1300 | static struct cfq_io_context * |
8267e268 | 1301 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1302 | { |
22e2c507 | 1303 | struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); |
1da177e4 LT |
1304 | |
1305 | if (cic) { | |
e2d74ac0 JA |
1306 | RB_CLEAR(&cic->rb_node); |
1307 | cic->key = NULL; | |
12a05732 AV |
1308 | cic->cfqq[ASYNC] = NULL; |
1309 | cic->cfqq[SYNC] = NULL; | |
22e2c507 JA |
1310 | cic->last_end_request = jiffies; |
1311 | cic->ttime_total = 0; | |
1312 | cic->ttime_samples = 0; | |
1313 | cic->ttime_mean = 0; | |
1314 | cic->dtor = cfq_free_io_context; | |
1315 | cic->exit = cfq_exit_io_context; | |
d9ff4187 | 1316 | INIT_LIST_HEAD(&cic->queue_list); |
334e94de | 1317 | atomic_inc(&ioc_count); |
1da177e4 LT |
1318 | } |
1319 | ||
1320 | return cic; | |
1321 | } | |
1322 | ||
22e2c507 JA |
1323 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1324 | { | |
1325 | struct task_struct *tsk = current; | |
1326 | int ioprio_class; | |
1327 | ||
3b18152c | 1328 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1329 | return; |
1330 | ||
1331 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1332 | switch (ioprio_class) { | |
1333 | default: | |
1334 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1335 | case IOPRIO_CLASS_NONE: | |
1336 | /* | |
1337 | * no prio set, place us in the middle of the BE classes | |
1338 | */ | |
1339 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1340 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1341 | break; | |
1342 | case IOPRIO_CLASS_RT: | |
1343 | cfqq->ioprio = task_ioprio(tsk); | |
1344 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1345 | break; | |
1346 | case IOPRIO_CLASS_BE: | |
1347 | cfqq->ioprio = task_ioprio(tsk); | |
1348 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1349 | break; | |
1350 | case IOPRIO_CLASS_IDLE: | |
1351 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1352 | cfqq->ioprio = 7; | |
3b18152c | 1353 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1354 | break; |
1355 | } | |
1356 | ||
1357 | /* | |
1358 | * keep track of original prio settings in case we have to temporarily | |
1359 | * elevate the priority of this queue | |
1360 | */ | |
1361 | cfqq->org_ioprio = cfqq->ioprio; | |
1362 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1363 | ||
3b18152c | 1364 | if (cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1365 | cfq_resort_rr_list(cfqq, 0); |
1366 | ||
3b18152c | 1367 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1368 | } |
1369 | ||
478a82b0 | 1370 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1371 | { |
478a82b0 AV |
1372 | struct cfq_data *cfqd = cic->key; |
1373 | struct cfq_queue *cfqq; | |
1374 | if (cfqd) { | |
22e2c507 | 1375 | spin_lock(cfqd->queue->queue_lock); |
12a05732 AV |
1376 | cfqq = cic->cfqq[ASYNC]; |
1377 | if (cfqq) { | |
6f325a13 AV |
1378 | struct cfq_queue *new_cfqq; |
1379 | new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC, | |
1380 | cic->ioc->task, GFP_ATOMIC); | |
1381 | if (new_cfqq) { | |
1382 | cic->cfqq[ASYNC] = new_cfqq; | |
1383 | cfq_put_queue(cfqq); | |
1384 | } | |
12a05732 AV |
1385 | } |
1386 | cfqq = cic->cfqq[SYNC]; | |
478a82b0 AV |
1387 | if (cfqq) { |
1388 | cfq_mark_cfqq_prio_changed(cfqq); | |
1389 | cfq_init_prio_data(cfqq); | |
1390 | } | |
22e2c507 JA |
1391 | spin_unlock(cfqd->queue->queue_lock); |
1392 | } | |
1393 | } | |
1394 | ||
1395 | /* | |
1396 | * callback from sys_ioprio_set, irqs are disabled | |
1397 | */ | |
1398 | static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) | |
1399 | { | |
a6a0763a | 1400 | struct cfq_io_context *cic; |
e2d74ac0 | 1401 | struct rb_node *n; |
a6a0763a AV |
1402 | |
1403 | write_lock(&cfq_exit_lock); | |
1404 | ||
e2d74ac0 JA |
1405 | n = rb_first(&ioc->cic_root); |
1406 | while (n != NULL) { | |
1407 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1408 | ||
478a82b0 | 1409 | changed_ioprio(cic); |
e2d74ac0 JA |
1410 | n = rb_next(n); |
1411 | } | |
22e2c507 | 1412 | |
a6a0763a AV |
1413 | write_unlock(&cfq_exit_lock); |
1414 | ||
22e2c507 JA |
1415 | return 0; |
1416 | } | |
1417 | ||
1418 | static struct cfq_queue * | |
6f325a13 | 1419 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, |
8267e268 | 1420 | gfp_t gfp_mask) |
22e2c507 JA |
1421 | { |
1422 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1423 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
6f325a13 | 1424 | unsigned short ioprio; |
22e2c507 JA |
1425 | |
1426 | retry: | |
6f325a13 | 1427 | ioprio = tsk->ioprio; |
3b18152c | 1428 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); |
22e2c507 JA |
1429 | |
1430 | if (!cfqq) { | |
1431 | if (new_cfqq) { | |
1432 | cfqq = new_cfqq; | |
1433 | new_cfqq = NULL; | |
1434 | } else if (gfp_mask & __GFP_WAIT) { | |
1435 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1436 | new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1437 | spin_lock_irq(cfqd->queue->queue_lock); | |
1438 | goto retry; | |
1439 | } else { | |
1440 | cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1441 | if (!cfqq) | |
1442 | goto out; | |
1443 | } | |
1444 | ||
1445 | memset(cfqq, 0, sizeof(*cfqq)); | |
1446 | ||
1447 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1448 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
1449 | RB_CLEAR_ROOT(&cfqq->sort_list); | |
1450 | INIT_LIST_HEAD(&cfqq->fifo); | |
1451 | ||
1452 | cfqq->key = key; | |
1453 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1454 | atomic_set(&cfqq->ref, 0); | |
1455 | cfqq->cfqd = cfqd; | |
22e2c507 JA |
1456 | cfqq->service_last = 0; |
1457 | /* | |
1458 | * set ->slice_left to allow preemption for a new process | |
1459 | */ | |
1460 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
3b18152c JA |
1461 | cfq_mark_cfqq_idle_window(cfqq); |
1462 | cfq_mark_cfqq_prio_changed(cfqq); | |
1463 | cfq_init_prio_data(cfqq); | |
22e2c507 JA |
1464 | } |
1465 | ||
1466 | if (new_cfqq) | |
1467 | kmem_cache_free(cfq_pool, new_cfqq); | |
1468 | ||
1469 | atomic_inc(&cfqq->ref); | |
1470 | out: | |
1471 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1472 | return cfqq; | |
1473 | } | |
1474 | ||
dbecf3ab OH |
1475 | static void |
1476 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1477 | { | |
1478 | read_lock(&cfq_exit_lock); | |
1479 | rb_erase(&cic->rb_node, &ioc->cic_root); | |
1480 | read_unlock(&cfq_exit_lock); | |
1481 | kmem_cache_free(cfq_ioc_pool, cic); | |
1482 | atomic_dec(&ioc_count); | |
1483 | } | |
1484 | ||
e2d74ac0 JA |
1485 | static struct cfq_io_context * |
1486 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1487 | { | |
dbecf3ab | 1488 | struct rb_node *n; |
e2d74ac0 | 1489 | struct cfq_io_context *cic; |
be3b0753 | 1490 | void *k, *key = cfqd; |
e2d74ac0 | 1491 | |
dbecf3ab OH |
1492 | restart: |
1493 | n = ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1494 | while (n) { |
1495 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1496 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1497 | k = cic->key; | |
1498 | if (unlikely(!k)) { | |
dbecf3ab OH |
1499 | cfq_drop_dead_cic(ioc, cic); |
1500 | goto restart; | |
1501 | } | |
e2d74ac0 | 1502 | |
be3b0753 | 1503 | if (key < k) |
e2d74ac0 | 1504 | n = n->rb_left; |
be3b0753 | 1505 | else if (key > k) |
e2d74ac0 JA |
1506 | n = n->rb_right; |
1507 | else | |
1508 | return cic; | |
1509 | } | |
1510 | ||
1511 | return NULL; | |
1512 | } | |
1513 | ||
1514 | static inline void | |
1515 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1516 | struct cfq_io_context *cic) | |
1517 | { | |
dbecf3ab OH |
1518 | struct rb_node **p; |
1519 | struct rb_node *parent; | |
e2d74ac0 | 1520 | struct cfq_io_context *__cic; |
be3b0753 | 1521 | void *k; |
e2d74ac0 | 1522 | |
e2d74ac0 JA |
1523 | cic->ioc = ioc; |
1524 | cic->key = cfqd; | |
1525 | ||
1526 | ioc->set_ioprio = cfq_ioc_set_ioprio; | |
dbecf3ab OH |
1527 | restart: |
1528 | parent = NULL; | |
1529 | p = &ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1530 | while (*p) { |
1531 | parent = *p; | |
1532 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1533 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1534 | k = __cic->key; | |
1535 | if (unlikely(!k)) { | |
dbecf3ab OH |
1536 | cfq_drop_dead_cic(ioc, cic); |
1537 | goto restart; | |
1538 | } | |
e2d74ac0 | 1539 | |
be3b0753 | 1540 | if (cic->key < k) |
e2d74ac0 | 1541 | p = &(*p)->rb_left; |
be3b0753 | 1542 | else if (cic->key > k) |
e2d74ac0 JA |
1543 | p = &(*p)->rb_right; |
1544 | else | |
1545 | BUG(); | |
1546 | } | |
1547 | ||
dbecf3ab | 1548 | read_lock(&cfq_exit_lock); |
e2d74ac0 JA |
1549 | rb_link_node(&cic->rb_node, parent, p); |
1550 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
1551 | list_add(&cic->queue_list, &cfqd->cic_list); | |
1552 | read_unlock(&cfq_exit_lock); | |
1553 | } | |
1554 | ||
1da177e4 LT |
1555 | /* |
1556 | * Setup general io context and cfq io context. There can be several cfq | |
1557 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1558 | * than one device managed by cfq. |
1da177e4 LT |
1559 | */ |
1560 | static struct cfq_io_context * | |
e2d74ac0 | 1561 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1562 | { |
22e2c507 | 1563 | struct io_context *ioc = NULL; |
1da177e4 | 1564 | struct cfq_io_context *cic; |
1da177e4 | 1565 | |
22e2c507 | 1566 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1567 | |
22e2c507 | 1568 | ioc = get_io_context(gfp_mask); |
1da177e4 LT |
1569 | if (!ioc) |
1570 | return NULL; | |
1571 | ||
e2d74ac0 JA |
1572 | cic = cfq_cic_rb_lookup(cfqd, ioc); |
1573 | if (cic) | |
1574 | goto out; | |
1da177e4 | 1575 | |
e2d74ac0 JA |
1576 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1577 | if (cic == NULL) | |
1578 | goto err; | |
1da177e4 | 1579 | |
e2d74ac0 | 1580 | cfq_cic_link(cfqd, ioc, cic); |
1da177e4 | 1581 | out: |
1da177e4 LT |
1582 | return cic; |
1583 | err: | |
1584 | put_io_context(ioc); | |
1585 | return NULL; | |
1586 | } | |
1587 | ||
22e2c507 JA |
1588 | static void |
1589 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1590 | { |
22e2c507 | 1591 | unsigned long elapsed, ttime; |
1da177e4 | 1592 | |
22e2c507 JA |
1593 | /* |
1594 | * if this context already has stuff queued, thinktime is from | |
1595 | * last queue not last end | |
1596 | */ | |
1597 | #if 0 | |
1598 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1599 | elapsed = jiffies - cic->last_end_request; | |
1600 | else | |
1601 | elapsed = jiffies - cic->last_queue; | |
1602 | #else | |
1603 | elapsed = jiffies - cic->last_end_request; | |
1604 | #endif | |
1da177e4 | 1605 | |
22e2c507 | 1606 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
db3b5848 | 1607 | |
22e2c507 JA |
1608 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1609 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1610 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1611 | } | |
1da177e4 | 1612 | |
206dc69b JA |
1613 | static void |
1614 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
1615 | struct cfq_rq *crq) | |
1616 | { | |
1617 | sector_t sdist; | |
1618 | u64 total; | |
1619 | ||
1620 | if (cic->last_request_pos < crq->request->sector) | |
1621 | sdist = crq->request->sector - cic->last_request_pos; | |
1622 | else | |
1623 | sdist = cic->last_request_pos - crq->request->sector; | |
1624 | ||
1625 | /* | |
1626 | * Don't allow the seek distance to get too large from the | |
1627 | * odd fragment, pagein, etc | |
1628 | */ | |
1629 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1630 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1631 | else | |
1632 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1633 | ||
1634 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1635 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1636 | total = cic->seek_total + (cic->seek_samples/2); | |
1637 | do_div(total, cic->seek_samples); | |
1638 | cic->seek_mean = (sector_t)total; | |
1639 | } | |
1da177e4 | 1640 | |
22e2c507 JA |
1641 | /* |
1642 | * Disable idle window if the process thinks too long or seeks so much that | |
1643 | * it doesn't matter | |
1644 | */ | |
1645 | static void | |
1646 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1647 | struct cfq_io_context *cic) | |
1648 | { | |
3b18152c | 1649 | int enable_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1650 | |
22e2c507 JA |
1651 | if (!cic->ioc->task || !cfqd->cfq_slice_idle) |
1652 | enable_idle = 0; | |
1653 | else if (sample_valid(cic->ttime_samples)) { | |
1654 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1655 | enable_idle = 0; | |
1656 | else | |
1657 | enable_idle = 1; | |
1da177e4 LT |
1658 | } |
1659 | ||
3b18152c JA |
1660 | if (enable_idle) |
1661 | cfq_mark_cfqq_idle_window(cfqq); | |
1662 | else | |
1663 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1664 | } |
1da177e4 | 1665 | |
22e2c507 JA |
1666 | |
1667 | /* | |
1668 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1669 | * no or if we aren't sure, a 1 will cause a preempt. | |
1670 | */ | |
1671 | static int | |
1672 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1673 | struct cfq_rq *crq) | |
1674 | { | |
1675 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1676 | ||
1677 | if (cfq_class_idle(new_cfqq)) | |
1678 | return 0; | |
1679 | ||
1680 | if (!cfqq) | |
1681 | return 1; | |
1682 | ||
1683 | if (cfq_class_idle(cfqq)) | |
1684 | return 1; | |
3b18152c | 1685 | if (!cfq_cfqq_wait_request(new_cfqq)) |
22e2c507 JA |
1686 | return 0; |
1687 | /* | |
1688 | * if it doesn't have slice left, forget it | |
1689 | */ | |
1690 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1691 | return 0; | |
3b18152c | 1692 | if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 JA |
1693 | return 1; |
1694 | ||
1695 | return 0; | |
1696 | } | |
1697 | ||
1698 | /* | |
1699 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1700 | * let it have half of its nominal slice. | |
1701 | */ | |
1702 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1703 | { | |
1704 | struct cfq_queue *__cfqq, *next; | |
1705 | ||
1706 | list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) | |
1707 | cfq_resort_rr_list(__cfqq, 1); | |
1708 | ||
1709 | if (!cfqq->slice_left) | |
1710 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1711 | ||
1712 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
3b18152c | 1713 | __cfq_slice_expired(cfqd, cfqq, 1); |
22e2c507 JA |
1714 | __cfq_set_active_queue(cfqd, cfqq); |
1715 | } | |
1716 | ||
1717 | /* | |
1718 | * should really be a ll_rw_blk.c helper | |
1719 | */ | |
1720 | static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1721 | { | |
1722 | request_queue_t *q = cfqd->queue; | |
1723 | ||
1724 | if (!blk_queue_plugged(q)) | |
1725 | q->request_fn(q); | |
1726 | else | |
1727 | __generic_unplug_device(q); | |
1728 | } | |
1729 | ||
1730 | /* | |
1731 | * Called when a new fs request (crq) is added (to cfqq). Check if there's | |
1732 | * something we should do about it | |
1733 | */ | |
1734 | static void | |
1735 | cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1736 | struct cfq_rq *crq) | |
1737 | { | |
9c2c38a1 | 1738 | struct cfq_io_context *cic; |
22e2c507 JA |
1739 | |
1740 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
1741 | ||
9c2c38a1 JA |
1742 | /* |
1743 | * we never wait for an async request and we don't allow preemption | |
1744 | * of an async request. so just return early | |
1745 | */ | |
1746 | if (!cfq_crq_is_sync(crq)) | |
1747 | return; | |
22e2c507 | 1748 | |
9c2c38a1 | 1749 | cic = crq->io_context; |
22e2c507 | 1750 | |
9c2c38a1 | 1751 | cfq_update_io_thinktime(cfqd, cic); |
206dc69b | 1752 | cfq_update_io_seektime(cfqd, cic, crq); |
9c2c38a1 JA |
1753 | cfq_update_idle_window(cfqd, cfqq, cic); |
1754 | ||
1755 | cic->last_queue = jiffies; | |
206dc69b | 1756 | cic->last_request_pos = crq->request->sector + crq->request->nr_sectors; |
22e2c507 JA |
1757 | |
1758 | if (cfqq == cfqd->active_queue) { | |
1759 | /* | |
1760 | * if we are waiting for a request for this queue, let it rip | |
1761 | * immediately and flag that we must not expire this queue | |
1762 | * just now | |
1763 | */ | |
3b18152c JA |
1764 | if (cfq_cfqq_wait_request(cfqq)) { |
1765 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 JA |
1766 | del_timer(&cfqd->idle_slice_timer); |
1767 | cfq_start_queueing(cfqd, cfqq); | |
1768 | } | |
1769 | } else if (cfq_should_preempt(cfqd, cfqq, crq)) { | |
1770 | /* | |
1771 | * not the active queue - expire current slice if it is | |
1772 | * idle and has expired it's mean thinktime or this new queue | |
1773 | * has some old slice time left and is of higher priority | |
1774 | */ | |
1775 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1776 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
1777 | cfq_start_queueing(cfqd, cfqq); |
1778 | } | |
1da177e4 LT |
1779 | } |
1780 | ||
b4878f24 | 1781 | static void cfq_insert_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1782 | { |
b4878f24 | 1783 | struct cfq_data *cfqd = q->elevator->elevator_data; |
22e2c507 JA |
1784 | struct cfq_rq *crq = RQ_DATA(rq); |
1785 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1786 | ||
1787 | cfq_init_prio_data(cfqq); | |
1da177e4 LT |
1788 | |
1789 | cfq_add_crq_rb(crq); | |
1da177e4 | 1790 | |
22e2c507 JA |
1791 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1792 | ||
98b11471 | 1793 | if (rq_mergeable(rq)) |
22e2c507 JA |
1794 | cfq_add_crq_hash(cfqd, crq); |
1795 | ||
22e2c507 | 1796 | cfq_crq_enqueued(cfqd, cfqq, crq); |
1da177e4 LT |
1797 | } |
1798 | ||
1da177e4 LT |
1799 | static void cfq_completed_request(request_queue_t *q, struct request *rq) |
1800 | { | |
1801 | struct cfq_rq *crq = RQ_DATA(rq); | |
b4878f24 JA |
1802 | struct cfq_queue *cfqq = crq->cfq_queue; |
1803 | struct cfq_data *cfqd = cfqq->cfqd; | |
1804 | const int sync = cfq_crq_is_sync(crq); | |
1805 | unsigned long now; | |
1da177e4 | 1806 | |
b4878f24 | 1807 | now = jiffies; |
1da177e4 | 1808 | |
b4878f24 JA |
1809 | WARN_ON(!cfqd->rq_in_driver); |
1810 | WARN_ON(!cfqq->on_dispatch[sync]); | |
1811 | cfqd->rq_in_driver--; | |
1812 | cfqq->on_dispatch[sync]--; | |
1da177e4 | 1813 | |
b4878f24 JA |
1814 | if (!cfq_class_idle(cfqq)) |
1815 | cfqd->last_end_request = now; | |
3b18152c | 1816 | |
b4878f24 JA |
1817 | if (!cfq_cfqq_dispatched(cfqq)) { |
1818 | if (cfq_cfqq_on_rr(cfqq)) { | |
1819 | cfqq->service_last = now; | |
1820 | cfq_resort_rr_list(cfqq, 0); | |
1821 | } | |
7b14e3b5 | 1822 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1823 | } |
1824 | ||
b4878f24 JA |
1825 | if (cfq_crq_is_sync(crq)) |
1826 | crq->io_context->last_end_request = now; | |
1da177e4 LT |
1827 | } |
1828 | ||
1829 | static struct request * | |
1830 | cfq_former_request(request_queue_t *q, struct request *rq) | |
1831 | { | |
1832 | struct cfq_rq *crq = RQ_DATA(rq); | |
1833 | struct rb_node *rbprev = rb_prev(&crq->rb_node); | |
1834 | ||
1835 | if (rbprev) | |
1836 | return rb_entry_crq(rbprev)->request; | |
1837 | ||
1838 | return NULL; | |
1839 | } | |
1840 | ||
1841 | static struct request * | |
1842 | cfq_latter_request(request_queue_t *q, struct request *rq) | |
1843 | { | |
1844 | struct cfq_rq *crq = RQ_DATA(rq); | |
1845 | struct rb_node *rbnext = rb_next(&crq->rb_node); | |
1846 | ||
1847 | if (rbnext) | |
1848 | return rb_entry_crq(rbnext)->request; | |
1849 | ||
1850 | return NULL; | |
1851 | } | |
1852 | ||
22e2c507 JA |
1853 | /* |
1854 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1855 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1856 | */ | |
1857 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1858 | { |
22e2c507 JA |
1859 | const int ioprio_class = cfqq->ioprio_class; |
1860 | const int ioprio = cfqq->ioprio; | |
1da177e4 | 1861 | |
22e2c507 JA |
1862 | if (has_fs_excl()) { |
1863 | /* | |
1864 | * boost idle prio on transactions that would lock out other | |
1865 | * users of the filesystem | |
1866 | */ | |
1867 | if (cfq_class_idle(cfqq)) | |
1868 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1869 | if (cfqq->ioprio > IOPRIO_NORM) | |
1870 | cfqq->ioprio = IOPRIO_NORM; | |
1871 | } else { | |
1872 | /* | |
1873 | * check if we need to unboost the queue | |
1874 | */ | |
1875 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1876 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1877 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1878 | cfqq->ioprio = cfqq->org_ioprio; | |
1879 | } | |
1da177e4 | 1880 | |
22e2c507 JA |
1881 | /* |
1882 | * refile between round-robin lists if we moved the priority class | |
1883 | */ | |
1884 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
3b18152c | 1885 | cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1886 | cfq_resort_rr_list(cfqq, 0); |
1887 | } | |
1da177e4 | 1888 | |
22e2c507 JA |
1889 | static inline int |
1890 | __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1891 | struct task_struct *task, int rw) | |
1892 | { | |
3b18152c JA |
1893 | #if 1 |
1894 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && | |
99f95e52 | 1895 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1896 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1897 | return ELV_MQUEUE_MUST; |
3b18152c | 1898 | } |
1da177e4 | 1899 | |
22e2c507 | 1900 | return ELV_MQUEUE_MAY; |
3b18152c | 1901 | #else |
22e2c507 JA |
1902 | if (!cfqq || task->flags & PF_MEMALLOC) |
1903 | return ELV_MQUEUE_MAY; | |
3b18152c JA |
1904 | if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { |
1905 | if (cfq_cfqq_wait_request(cfqq)) | |
22e2c507 | 1906 | return ELV_MQUEUE_MUST; |
1da177e4 | 1907 | |
22e2c507 JA |
1908 | /* |
1909 | * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we | |
1910 | * can quickly flood the queue with writes from a single task | |
1911 | */ | |
99f95e52 | 1912 | if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1913 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1914 | return ELV_MQUEUE_MUST; |
1da177e4 | 1915 | } |
22e2c507 JA |
1916 | |
1917 | return ELV_MQUEUE_MAY; | |
1da177e4 | 1918 | } |
22e2c507 JA |
1919 | if (cfq_class_idle(cfqq)) |
1920 | return ELV_MQUEUE_NO; | |
1921 | if (cfqq->allocated[rw] >= cfqd->max_queued) { | |
1922 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
1923 | int ret = ELV_MQUEUE_NO; | |
1da177e4 | 1924 | |
22e2c507 JA |
1925 | if (ioc && ioc->nr_batch_requests) |
1926 | ret = ELV_MQUEUE_MAY; | |
1927 | ||
1928 | put_io_context(ioc); | |
1929 | return ret; | |
1930 | } | |
1931 | ||
1932 | return ELV_MQUEUE_MAY; | |
1933 | #endif | |
1934 | } | |
1935 | ||
1936 | static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) | |
1937 | { | |
1938 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1939 | struct task_struct *tsk = current; | |
1940 | struct cfq_queue *cfqq; | |
1941 | ||
1942 | /* | |
1943 | * don't force setup of a queue from here, as a call to may_queue | |
1944 | * does not necessarily imply that a request actually will be queued. | |
1945 | * so just lookup a possibly existing queue, or return 'may queue' | |
1946 | * if that fails | |
1947 | */ | |
3b18152c | 1948 | cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); |
22e2c507 JA |
1949 | if (cfqq) { |
1950 | cfq_init_prio_data(cfqq); | |
1951 | cfq_prio_boost(cfqq); | |
1952 | ||
1953 | return __cfq_may_queue(cfqd, cfqq, tsk, rw); | |
1954 | } | |
1955 | ||
1956 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1957 | } |
1958 | ||
1959 | static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) | |
1960 | { | |
22e2c507 | 1961 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 | 1962 | struct request_list *rl = &q->rq; |
1da177e4 | 1963 | |
22e2c507 JA |
1964 | if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { |
1965 | smp_mb(); | |
1966 | if (waitqueue_active(&rl->wait[READ])) | |
1967 | wake_up(&rl->wait[READ]); | |
1968 | } | |
1969 | ||
1970 | if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { | |
1971 | smp_mb(); | |
1972 | if (waitqueue_active(&rl->wait[WRITE])) | |
1973 | wake_up(&rl->wait[WRITE]); | |
1974 | } | |
1da177e4 LT |
1975 | } |
1976 | ||
1977 | /* | |
1978 | * queue lock held here | |
1979 | */ | |
1980 | static void cfq_put_request(request_queue_t *q, struct request *rq) | |
1981 | { | |
1982 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1983 | struct cfq_rq *crq = RQ_DATA(rq); | |
1984 | ||
1985 | if (crq) { | |
1986 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 | 1987 | const int rw = rq_data_dir(rq); |
1da177e4 | 1988 | |
22e2c507 JA |
1989 | BUG_ON(!cfqq->allocated[rw]); |
1990 | cfqq->allocated[rw]--; | |
1da177e4 | 1991 | |
22e2c507 | 1992 | put_io_context(crq->io_context->ioc); |
1da177e4 LT |
1993 | |
1994 | mempool_free(crq, cfqd->crq_pool); | |
1995 | rq->elevator_private = NULL; | |
1996 | ||
1da177e4 LT |
1997 | cfq_check_waiters(q, cfqq); |
1998 | cfq_put_queue(cfqq); | |
1999 | } | |
2000 | } | |
2001 | ||
2002 | /* | |
22e2c507 | 2003 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2004 | */ |
22e2c507 JA |
2005 | static int |
2006 | cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, | |
8267e268 | 2007 | gfp_t gfp_mask) |
1da177e4 LT |
2008 | { |
2009 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 2010 | struct task_struct *tsk = current; |
1da177e4 LT |
2011 | struct cfq_io_context *cic; |
2012 | const int rw = rq_data_dir(rq); | |
3b18152c | 2013 | pid_t key = cfq_queue_pid(tsk, rw); |
22e2c507 | 2014 | struct cfq_queue *cfqq; |
1da177e4 LT |
2015 | struct cfq_rq *crq; |
2016 | unsigned long flags; | |
12a05732 | 2017 | int is_sync = key != CFQ_KEY_ASYNC; |
1da177e4 LT |
2018 | |
2019 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2020 | ||
e2d74ac0 | 2021 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2022 | |
1da177e4 LT |
2023 | spin_lock_irqsave(q->queue_lock, flags); |
2024 | ||
22e2c507 JA |
2025 | if (!cic) |
2026 | goto queue_fail; | |
2027 | ||
12a05732 | 2028 | if (!cic->cfqq[is_sync]) { |
6f325a13 | 2029 | cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask); |
22e2c507 JA |
2030 | if (!cfqq) |
2031 | goto queue_fail; | |
1da177e4 | 2032 | |
12a05732 | 2033 | cic->cfqq[is_sync] = cfqq; |
22e2c507 | 2034 | } else |
12a05732 | 2035 | cfqq = cic->cfqq[is_sync]; |
1da177e4 LT |
2036 | |
2037 | cfqq->allocated[rw]++; | |
3b18152c | 2038 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 JA |
2039 | cfqd->rq_starved = 0; |
2040 | atomic_inc(&cfqq->ref); | |
1da177e4 LT |
2041 | spin_unlock_irqrestore(q->queue_lock, flags); |
2042 | ||
1da177e4 LT |
2043 | crq = mempool_alloc(cfqd->crq_pool, gfp_mask); |
2044 | if (crq) { | |
2045 | RB_CLEAR(&crq->rb_node); | |
2046 | crq->rb_key = 0; | |
2047 | crq->request = rq; | |
2048 | INIT_HLIST_NODE(&crq->hash); | |
2049 | crq->cfq_queue = cfqq; | |
2050 | crq->io_context = cic; | |
3b18152c | 2051 | |
12a05732 | 2052 | if (is_sync) |
3b18152c JA |
2053 | cfq_mark_crq_is_sync(crq); |
2054 | else | |
2055 | cfq_clear_crq_is_sync(crq); | |
2056 | ||
1da177e4 | 2057 | rq->elevator_private = crq; |
1da177e4 LT |
2058 | return 0; |
2059 | } | |
2060 | ||
1da177e4 LT |
2061 | spin_lock_irqsave(q->queue_lock, flags); |
2062 | cfqq->allocated[rw]--; | |
22e2c507 | 2063 | if (!(cfqq->allocated[0] + cfqq->allocated[1])) |
3b18152c | 2064 | cfq_mark_cfqq_must_alloc(cfqq); |
1da177e4 | 2065 | cfq_put_queue(cfqq); |
22e2c507 JA |
2066 | queue_fail: |
2067 | if (cic) | |
2068 | put_io_context(cic->ioc); | |
2069 | /* | |
2070 | * mark us rq allocation starved. we need to kickstart the process | |
2071 | * ourselves if there are no pending requests that can do it for us. | |
2072 | * that would be an extremely rare OOM situation | |
2073 | */ | |
2074 | cfqd->rq_starved = 1; | |
3b18152c | 2075 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2076 | spin_unlock_irqrestore(q->queue_lock, flags); |
2077 | return 1; | |
2078 | } | |
2079 | ||
22e2c507 JA |
2080 | static void cfq_kick_queue(void *data) |
2081 | { | |
2082 | request_queue_t *q = data; | |
2083 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2084 | unsigned long flags; | |
2085 | ||
2086 | spin_lock_irqsave(q->queue_lock, flags); | |
2087 | ||
2088 | if (cfqd->rq_starved) { | |
2089 | struct request_list *rl = &q->rq; | |
2090 | ||
2091 | /* | |
2092 | * we aren't guaranteed to get a request after this, but we | |
2093 | * have to be opportunistic | |
2094 | */ | |
2095 | smp_mb(); | |
2096 | if (waitqueue_active(&rl->wait[READ])) | |
2097 | wake_up(&rl->wait[READ]); | |
2098 | if (waitqueue_active(&rl->wait[WRITE])) | |
2099 | wake_up(&rl->wait[WRITE]); | |
2100 | } | |
2101 | ||
2102 | blk_remove_plug(q); | |
2103 | q->request_fn(q); | |
2104 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2105 | } | |
2106 | ||
2107 | /* | |
2108 | * Timer running if the active_queue is currently idling inside its time slice | |
2109 | */ | |
2110 | static void cfq_idle_slice_timer(unsigned long data) | |
2111 | { | |
2112 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2113 | struct cfq_queue *cfqq; | |
2114 | unsigned long flags; | |
2115 | ||
2116 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2117 | ||
2118 | if ((cfqq = cfqd->active_queue) != NULL) { | |
2119 | unsigned long now = jiffies; | |
2120 | ||
2121 | /* | |
2122 | * expired | |
2123 | */ | |
2124 | if (time_after(now, cfqq->slice_end)) | |
2125 | goto expire; | |
2126 | ||
2127 | /* | |
2128 | * only expire and reinvoke request handler, if there are | |
2129 | * other queues with pending requests | |
2130 | */ | |
b4878f24 | 2131 | if (!cfqd->busy_queues) { |
22e2c507 JA |
2132 | cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); |
2133 | add_timer(&cfqd->idle_slice_timer); | |
2134 | goto out_cont; | |
2135 | } | |
2136 | ||
2137 | /* | |
2138 | * not expired and it has a request pending, let it dispatch | |
2139 | */ | |
2140 | if (!RB_EMPTY(&cfqq->sort_list)) { | |
3b18152c | 2141 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2142 | goto out_kick; |
2143 | } | |
2144 | } | |
2145 | expire: | |
2146 | cfq_slice_expired(cfqd, 0); | |
2147 | out_kick: | |
3b18152c | 2148 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2149 | out_cont: |
2150 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2151 | } | |
2152 | ||
2153 | /* | |
2154 | * Timer running if an idle class queue is waiting for service | |
2155 | */ | |
2156 | static void cfq_idle_class_timer(unsigned long data) | |
2157 | { | |
2158 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2159 | unsigned long flags, end; | |
2160 | ||
2161 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2162 | ||
2163 | /* | |
2164 | * race with a non-idle queue, reset timer | |
2165 | */ | |
2166 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
2167 | if (!time_after_eq(jiffies, end)) { | |
2168 | cfqd->idle_class_timer.expires = end; | |
2169 | add_timer(&cfqd->idle_class_timer); | |
2170 | } else | |
3b18152c | 2171 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2172 | |
2173 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2174 | } | |
2175 | ||
3b18152c JA |
2176 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2177 | { | |
2178 | del_timer_sync(&cfqd->idle_slice_timer); | |
2179 | del_timer_sync(&cfqd->idle_class_timer); | |
2180 | blk_sync_queue(cfqd->queue); | |
2181 | } | |
22e2c507 | 2182 | |
1da177e4 LT |
2183 | static void cfq_exit_queue(elevator_t *e) |
2184 | { | |
22e2c507 | 2185 | struct cfq_data *cfqd = e->elevator_data; |
d9ff4187 | 2186 | request_queue_t *q = cfqd->queue; |
22e2c507 | 2187 | |
3b18152c | 2188 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2189 | |
d9ff4187 AV |
2190 | write_lock(&cfq_exit_lock); |
2191 | spin_lock_irq(q->queue_lock); | |
e2d74ac0 | 2192 | |
d9ff4187 AV |
2193 | if (cfqd->active_queue) |
2194 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); | |
e2d74ac0 JA |
2195 | |
2196 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2197 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2198 | struct cfq_io_context, | |
2199 | queue_list); | |
2200 | if (cic->cfqq[ASYNC]) { | |
2201 | cfq_put_queue(cic->cfqq[ASYNC]); | |
2202 | cic->cfqq[ASYNC] = NULL; | |
2203 | } | |
2204 | if (cic->cfqq[SYNC]) { | |
2205 | cfq_put_queue(cic->cfqq[SYNC]); | |
2206 | cic->cfqq[SYNC] = NULL; | |
2207 | } | |
2208 | cic->key = NULL; | |
2209 | list_del_init(&cic->queue_list); | |
2210 | } | |
e2d74ac0 | 2211 | |
d9ff4187 AV |
2212 | spin_unlock_irq(q->queue_lock); |
2213 | write_unlock(&cfq_exit_lock); | |
a90d742e AV |
2214 | |
2215 | cfq_shutdown_timer_wq(cfqd); | |
2216 | ||
2217 | mempool_destroy(cfqd->crq_pool); | |
2218 | kfree(cfqd->crq_hash); | |
2219 | kfree(cfqd->cfq_hash); | |
2220 | kfree(cfqd); | |
1da177e4 LT |
2221 | } |
2222 | ||
2223 | static int cfq_init_queue(request_queue_t *q, elevator_t *e) | |
2224 | { | |
2225 | struct cfq_data *cfqd; | |
2226 | int i; | |
2227 | ||
2228 | cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); | |
2229 | if (!cfqd) | |
2230 | return -ENOMEM; | |
2231 | ||
2232 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 JA |
2233 | |
2234 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2235 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2236 | ||
2237 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2238 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2239 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
1da177e4 | 2240 | INIT_LIST_HEAD(&cfqd->empty_list); |
d9ff4187 | 2241 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 LT |
2242 | |
2243 | cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); | |
2244 | if (!cfqd->crq_hash) | |
2245 | goto out_crqhash; | |
2246 | ||
2247 | cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); | |
2248 | if (!cfqd->cfq_hash) | |
2249 | goto out_cfqhash; | |
2250 | ||
93d2341c | 2251 | cfqd->crq_pool = mempool_create_slab_pool(BLKDEV_MIN_RQ, crq_pool); |
1da177e4 LT |
2252 | if (!cfqd->crq_pool) |
2253 | goto out_crqpool; | |
2254 | ||
2255 | for (i = 0; i < CFQ_MHASH_ENTRIES; i++) | |
2256 | INIT_HLIST_HEAD(&cfqd->crq_hash[i]); | |
2257 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2258 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2259 | ||
2260 | e->elevator_data = cfqd; | |
2261 | ||
2262 | cfqd->queue = q; | |
1da177e4 | 2263 | |
22e2c507 | 2264 | cfqd->max_queued = q->nr_requests / 4; |
1da177e4 | 2265 | q->nr_batching = cfq_queued; |
22e2c507 JA |
2266 | |
2267 | init_timer(&cfqd->idle_slice_timer); | |
2268 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2269 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2270 | ||
2271 | init_timer(&cfqd->idle_class_timer); | |
2272 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2273 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2274 | ||
2275 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); | |
2276 | ||
1da177e4 LT |
2277 | cfqd->cfq_queued = cfq_queued; |
2278 | cfqd->cfq_quantum = cfq_quantum; | |
22e2c507 JA |
2279 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2280 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2281 | cfqd->cfq_back_max = cfq_back_max; |
2282 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2283 | cfqd->cfq_slice[0] = cfq_slice_async; |
2284 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2285 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2286 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2287 | |
1da177e4 LT |
2288 | return 0; |
2289 | out_crqpool: | |
2290 | kfree(cfqd->cfq_hash); | |
2291 | out_cfqhash: | |
2292 | kfree(cfqd->crq_hash); | |
2293 | out_crqhash: | |
2294 | kfree(cfqd); | |
2295 | return -ENOMEM; | |
2296 | } | |
2297 | ||
2298 | static void cfq_slab_kill(void) | |
2299 | { | |
2300 | if (crq_pool) | |
2301 | kmem_cache_destroy(crq_pool); | |
2302 | if (cfq_pool) | |
2303 | kmem_cache_destroy(cfq_pool); | |
2304 | if (cfq_ioc_pool) | |
2305 | kmem_cache_destroy(cfq_ioc_pool); | |
2306 | } | |
2307 | ||
2308 | static int __init cfq_slab_setup(void) | |
2309 | { | |
2310 | crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, | |
2311 | NULL, NULL); | |
2312 | if (!crq_pool) | |
2313 | goto fail; | |
2314 | ||
2315 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2316 | NULL, NULL); | |
2317 | if (!cfq_pool) | |
2318 | goto fail; | |
2319 | ||
2320 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2321 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2322 | if (!cfq_ioc_pool) | |
2323 | goto fail; | |
2324 | ||
2325 | return 0; | |
2326 | fail: | |
2327 | cfq_slab_kill(); | |
2328 | return -ENOMEM; | |
2329 | } | |
2330 | ||
1da177e4 LT |
2331 | /* |
2332 | * sysfs parts below --> | |
2333 | */ | |
1da177e4 LT |
2334 | |
2335 | static ssize_t | |
2336 | cfq_var_show(unsigned int var, char *page) | |
2337 | { | |
2338 | return sprintf(page, "%d\n", var); | |
2339 | } | |
2340 | ||
2341 | static ssize_t | |
2342 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2343 | { | |
2344 | char *p = (char *) page; | |
2345 | ||
2346 | *var = simple_strtoul(p, &p, 10); | |
2347 | return count; | |
2348 | } | |
2349 | ||
1da177e4 | 2350 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2351 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2352 | { \ |
3d1ab40f | 2353 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2354 | unsigned int __data = __VAR; \ |
2355 | if (__CONV) \ | |
2356 | __data = jiffies_to_msecs(__data); \ | |
2357 | return cfq_var_show(__data, (page)); \ | |
2358 | } | |
2359 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2360 | SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); | |
22e2c507 JA |
2361 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2362 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2363 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2364 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2365 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2366 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2367 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2368 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2369 | #undef SHOW_FUNCTION |
2370 | ||
2371 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2372 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2373 | { \ |
3d1ab40f | 2374 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2375 | unsigned int __data; \ |
2376 | int ret = cfq_var_store(&__data, (page), count); \ | |
2377 | if (__data < (MIN)) \ | |
2378 | __data = (MIN); \ | |
2379 | else if (__data > (MAX)) \ | |
2380 | __data = (MAX); \ | |
2381 | if (__CONV) \ | |
2382 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2383 | else \ | |
2384 | *(__PTR) = __data; \ | |
2385 | return ret; \ | |
2386 | } | |
2387 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2388 | STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); | |
22e2c507 JA |
2389 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2390 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2391 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2392 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2393 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2394 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2395 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2396 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2397 | #undef STORE_FUNCTION |
2398 | ||
e572ec7e AV |
2399 | #define CFQ_ATTR(name) \ |
2400 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2401 | ||
2402 | static struct elv_fs_entry cfq_attrs[] = { | |
2403 | CFQ_ATTR(quantum), | |
2404 | CFQ_ATTR(queued), | |
2405 | CFQ_ATTR(fifo_expire_sync), | |
2406 | CFQ_ATTR(fifo_expire_async), | |
2407 | CFQ_ATTR(back_seek_max), | |
2408 | CFQ_ATTR(back_seek_penalty), | |
2409 | CFQ_ATTR(slice_sync), | |
2410 | CFQ_ATTR(slice_async), | |
2411 | CFQ_ATTR(slice_async_rq), | |
2412 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2413 | __ATTR_NULL |
1da177e4 LT |
2414 | }; |
2415 | ||
1da177e4 LT |
2416 | static struct elevator_type iosched_cfq = { |
2417 | .ops = { | |
2418 | .elevator_merge_fn = cfq_merge, | |
2419 | .elevator_merged_fn = cfq_merged_request, | |
2420 | .elevator_merge_req_fn = cfq_merged_requests, | |
b4878f24 | 2421 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2422 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2423 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2424 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2425 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2426 | .elevator_completed_req_fn = cfq_completed_request, | |
2427 | .elevator_former_req_fn = cfq_former_request, | |
2428 | .elevator_latter_req_fn = cfq_latter_request, | |
2429 | .elevator_set_req_fn = cfq_set_request, | |
2430 | .elevator_put_req_fn = cfq_put_request, | |
2431 | .elevator_may_queue_fn = cfq_may_queue, | |
2432 | .elevator_init_fn = cfq_init_queue, | |
2433 | .elevator_exit_fn = cfq_exit_queue, | |
e17a9489 | 2434 | .trim = cfq_trim, |
1da177e4 | 2435 | }, |
3d1ab40f | 2436 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2437 | .elevator_name = "cfq", |
2438 | .elevator_owner = THIS_MODULE, | |
2439 | }; | |
2440 | ||
2441 | static int __init cfq_init(void) | |
2442 | { | |
2443 | int ret; | |
2444 | ||
22e2c507 JA |
2445 | /* |
2446 | * could be 0 on HZ < 1000 setups | |
2447 | */ | |
2448 | if (!cfq_slice_async) | |
2449 | cfq_slice_async = 1; | |
2450 | if (!cfq_slice_idle) | |
2451 | cfq_slice_idle = 1; | |
2452 | ||
1da177e4 LT |
2453 | if (cfq_slab_setup()) |
2454 | return -ENOMEM; | |
2455 | ||
2456 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2457 | if (ret) |
2458 | cfq_slab_kill(); | |
1da177e4 | 2459 | |
1da177e4 LT |
2460 | return ret; |
2461 | } | |
2462 | ||
2463 | static void __exit cfq_exit(void) | |
2464 | { | |
334e94de | 2465 | DECLARE_COMPLETION(all_gone); |
1da177e4 | 2466 | elv_unregister(&iosched_cfq); |
334e94de | 2467 | ioc_gone = &all_gone; |
fba82272 OH |
2468 | /* ioc_gone's update must be visible before reading ioc_count */ |
2469 | smp_wmb(); | |
334e94de | 2470 | if (atomic_read(&ioc_count)) |
fba82272 | 2471 | wait_for_completion(ioc_gone); |
334e94de | 2472 | synchronize_rcu(); |
83521d3e | 2473 | cfq_slab_kill(); |
1da177e4 LT |
2474 | } |
2475 | ||
2476 | module_init(cfq_init); | |
2477 | module_exit(cfq_exit); | |
2478 | ||
2479 | MODULE_AUTHOR("Jens Axboe"); | |
2480 | MODULE_LICENSE("GPL"); | |
2481 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |