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; |
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 | |
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 | */ | |
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; |
25776e35 | 136 | int hw_tag; |
1da177e4 | 137 | |
22e2c507 JA |
138 | /* |
139 | * schedule slice state info | |
140 | */ | |
141 | /* | |
142 | * idle window management | |
143 | */ | |
144 | struct timer_list idle_slice_timer; | |
145 | struct work_struct unplug_work; | |
1da177e4 | 146 | |
22e2c507 JA |
147 | struct cfq_queue *active_queue; |
148 | struct cfq_io_context *active_cic; | |
149 | int cur_prio, cur_end_prio; | |
150 | unsigned int dispatch_slice; | |
151 | ||
152 | struct timer_list idle_class_timer; | |
1da177e4 LT |
153 | |
154 | sector_t last_sector; | |
22e2c507 | 155 | unsigned long last_end_request; |
1da177e4 | 156 | |
22e2c507 | 157 | unsigned int rq_starved; |
1da177e4 LT |
158 | |
159 | /* | |
160 | * tunables, see top of file | |
161 | */ | |
162 | unsigned int cfq_quantum; | |
163 | unsigned int cfq_queued; | |
22e2c507 | 164 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
165 | unsigned int cfq_back_penalty; |
166 | unsigned int cfq_back_max; | |
22e2c507 JA |
167 | unsigned int cfq_slice[2]; |
168 | unsigned int cfq_slice_async_rq; | |
169 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
170 | |
171 | struct list_head cic_list; | |
1da177e4 LT |
172 | }; |
173 | ||
22e2c507 JA |
174 | /* |
175 | * Per process-grouping structure | |
176 | */ | |
1da177e4 LT |
177 | struct cfq_queue { |
178 | /* reference count */ | |
179 | atomic_t ref; | |
180 | /* parent cfq_data */ | |
181 | struct cfq_data *cfqd; | |
22e2c507 | 182 | /* cfqq lookup hash */ |
1da177e4 LT |
183 | struct hlist_node cfq_hash; |
184 | /* hash key */ | |
22e2c507 | 185 | unsigned int key; |
1da177e4 LT |
186 | /* on either rr or empty list of cfqd */ |
187 | struct list_head cfq_list; | |
188 | /* sorted list of pending requests */ | |
189 | struct rb_root sort_list; | |
190 | /* if fifo isn't expired, next request to serve */ | |
191 | struct cfq_rq *next_crq; | |
192 | /* requests queued in sort_list */ | |
193 | int queued[2]; | |
194 | /* currently allocated requests */ | |
195 | int allocated[2]; | |
196 | /* fifo list of requests in sort_list */ | |
22e2c507 | 197 | struct list_head fifo; |
1da177e4 | 198 | |
22e2c507 JA |
199 | unsigned long slice_start; |
200 | unsigned long slice_end; | |
201 | unsigned long slice_left; | |
202 | unsigned long service_last; | |
1da177e4 | 203 | |
3b18152c JA |
204 | /* number of requests that are on the dispatch list */ |
205 | int on_dispatch[2]; | |
22e2c507 JA |
206 | |
207 | /* io prio of this group */ | |
208 | unsigned short ioprio, org_ioprio; | |
209 | unsigned short ioprio_class, org_ioprio_class; | |
210 | ||
3b18152c JA |
211 | /* various state flags, see below */ |
212 | unsigned int flags; | |
1da177e4 LT |
213 | }; |
214 | ||
215 | struct cfq_rq { | |
216 | struct rb_node rb_node; | |
217 | sector_t rb_key; | |
218 | struct request *request; | |
219 | struct hlist_node hash; | |
220 | ||
221 | struct cfq_queue *cfq_queue; | |
222 | struct cfq_io_context *io_context; | |
223 | ||
3b18152c | 224 | unsigned int crq_flags; |
1da177e4 LT |
225 | }; |
226 | ||
3b18152c JA |
227 | enum cfqq_state_flags { |
228 | CFQ_CFQQ_FLAG_on_rr = 0, | |
229 | CFQ_CFQQ_FLAG_wait_request, | |
230 | CFQ_CFQQ_FLAG_must_alloc, | |
231 | CFQ_CFQQ_FLAG_must_alloc_slice, | |
232 | CFQ_CFQQ_FLAG_must_dispatch, | |
233 | CFQ_CFQQ_FLAG_fifo_expire, | |
234 | CFQ_CFQQ_FLAG_idle_window, | |
235 | CFQ_CFQQ_FLAG_prio_changed, | |
3b18152c JA |
236 | }; |
237 | ||
238 | #define CFQ_CFQQ_FNS(name) \ | |
239 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
240 | { \ | |
241 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
242 | } \ | |
243 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
244 | { \ | |
245 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
246 | } \ | |
247 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
248 | { \ | |
249 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
250 | } | |
251 | ||
252 | CFQ_CFQQ_FNS(on_rr); | |
253 | CFQ_CFQQ_FNS(wait_request); | |
254 | CFQ_CFQQ_FNS(must_alloc); | |
255 | CFQ_CFQQ_FNS(must_alloc_slice); | |
256 | CFQ_CFQQ_FNS(must_dispatch); | |
257 | CFQ_CFQQ_FNS(fifo_expire); | |
258 | CFQ_CFQQ_FNS(idle_window); | |
259 | CFQ_CFQQ_FNS(prio_changed); | |
3b18152c JA |
260 | #undef CFQ_CFQQ_FNS |
261 | ||
262 | enum cfq_rq_state_flags { | |
b4878f24 | 263 | CFQ_CRQ_FLAG_is_sync = 0, |
3b18152c JA |
264 | }; |
265 | ||
266 | #define CFQ_CRQ_FNS(name) \ | |
267 | static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ | |
268 | { \ | |
269 | crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ | |
270 | } \ | |
271 | static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ | |
272 | { \ | |
273 | crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ | |
274 | } \ | |
275 | static inline int cfq_crq_##name(const struct cfq_rq *crq) \ | |
276 | { \ | |
277 | return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ | |
278 | } | |
279 | ||
3b18152c | 280 | CFQ_CRQ_FNS(is_sync); |
3b18152c JA |
281 | #undef CFQ_CRQ_FNS |
282 | ||
283 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); | |
b4878f24 | 284 | static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); |
6f325a13 | 285 | static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); |
1da177e4 | 286 | |
22e2c507 | 287 | #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) |
1da177e4 LT |
288 | |
289 | /* | |
290 | * lots of deadline iosched dupes, can be abstracted later... | |
291 | */ | |
292 | static inline void cfq_del_crq_hash(struct cfq_rq *crq) | |
293 | { | |
294 | hlist_del_init(&crq->hash); | |
295 | } | |
296 | ||
1da177e4 LT |
297 | static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) |
298 | { | |
299 | const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); | |
300 | ||
1da177e4 LT |
301 | hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); |
302 | } | |
303 | ||
304 | static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) | |
305 | { | |
306 | struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; | |
307 | struct hlist_node *entry, *next; | |
308 | ||
309 | hlist_for_each_safe(entry, next, hash_list) { | |
310 | struct cfq_rq *crq = list_entry_hash(entry); | |
311 | struct request *__rq = crq->request; | |
312 | ||
1da177e4 LT |
313 | if (!rq_mergeable(__rq)) { |
314 | cfq_del_crq_hash(crq); | |
315 | continue; | |
316 | } | |
317 | ||
318 | if (rq_hash_key(__rq) == offset) | |
319 | return __rq; | |
320 | } | |
321 | ||
322 | return NULL; | |
323 | } | |
324 | ||
99f95e52 AM |
325 | /* |
326 | * scheduler run of queue, if there are requests pending and no one in the | |
327 | * driver that will restart queueing | |
328 | */ | |
329 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
330 | { | |
7b14e3b5 | 331 | if (cfqd->busy_queues) |
99f95e52 AM |
332 | kblockd_schedule_work(&cfqd->unplug_work); |
333 | } | |
334 | ||
335 | static int cfq_queue_empty(request_queue_t *q) | |
336 | { | |
337 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
338 | ||
b4878f24 | 339 | return !cfqd->busy_queues; |
99f95e52 AM |
340 | } |
341 | ||
206dc69b JA |
342 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) |
343 | { | |
344 | if (rw == READ || process_sync(task)) | |
345 | return task->pid; | |
346 | ||
347 | return CFQ_KEY_ASYNC; | |
348 | } | |
349 | ||
1da177e4 LT |
350 | /* |
351 | * Lifted from AS - choose which of crq1 and crq2 that is best served now. | |
352 | * We choose the request that is closest to the head right now. Distance | |
e8a99053 | 353 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 LT |
354 | */ |
355 | static struct cfq_rq * | |
356 | cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) | |
357 | { | |
358 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 359 | unsigned long back_max; |
e8a99053 AM |
360 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
361 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
362 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 LT |
363 | |
364 | if (crq1 == NULL || crq1 == crq2) | |
365 | return crq2; | |
366 | if (crq2 == NULL) | |
367 | return crq1; | |
9c2c38a1 | 368 | |
9c2c38a1 JA |
369 | if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) |
370 | return crq1; | |
371 | else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) | |
22e2c507 | 372 | return crq2; |
1da177e4 LT |
373 | |
374 | s1 = crq1->request->sector; | |
375 | s2 = crq2->request->sector; | |
376 | ||
377 | last = cfqd->last_sector; | |
378 | ||
1da177e4 LT |
379 | /* |
380 | * by definition, 1KiB is 2 sectors | |
381 | */ | |
382 | back_max = cfqd->cfq_back_max * 2; | |
383 | ||
384 | /* | |
385 | * Strict one way elevator _except_ in the case where we allow | |
386 | * short backward seeks which are biased as twice the cost of a | |
387 | * similar forward seek. | |
388 | */ | |
389 | if (s1 >= last) | |
390 | d1 = s1 - last; | |
391 | else if (s1 + back_max >= last) | |
392 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
393 | else | |
e8a99053 | 394 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
395 | |
396 | if (s2 >= last) | |
397 | d2 = s2 - last; | |
398 | else if (s2 + back_max >= last) | |
399 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
400 | else | |
e8a99053 | 401 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
402 | |
403 | /* Found required data */ | |
e8a99053 AM |
404 | |
405 | /* | |
406 | * By doing switch() on the bit mask "wrap" we avoid having to | |
407 | * check two variables for all permutations: --> faster! | |
408 | */ | |
409 | switch (wrap) { | |
410 | case 0: /* common case for CFQ: crq1 and crq2 not wrapped */ | |
411 | if (d1 < d2) | |
1da177e4 | 412 | return crq1; |
e8a99053 | 413 | else if (d2 < d1) |
1da177e4 | 414 | return crq2; |
e8a99053 AM |
415 | else { |
416 | if (s1 >= s2) | |
417 | return crq1; | |
418 | else | |
419 | return crq2; | |
420 | } | |
1da177e4 | 421 | |
e8a99053 | 422 | case CFQ_RQ2_WRAP: |
1da177e4 | 423 | return crq1; |
e8a99053 | 424 | case CFQ_RQ1_WRAP: |
1da177e4 | 425 | return crq2; |
e8a99053 AM |
426 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both crqs wrapped */ |
427 | default: | |
428 | /* | |
429 | * Since both rqs are wrapped, | |
430 | * start with the one that's further behind head | |
431 | * (--> only *one* back seek required), | |
432 | * since back seek takes more time than forward. | |
433 | */ | |
434 | if (s1 <= s2) | |
1da177e4 LT |
435 | return crq1; |
436 | else | |
437 | return crq2; | |
438 | } | |
439 | } | |
440 | ||
441 | /* | |
442 | * would be nice to take fifo expire time into account as well | |
443 | */ | |
444 | static struct cfq_rq * | |
445 | cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
446 | struct cfq_rq *last) | |
447 | { | |
448 | struct cfq_rq *crq_next = NULL, *crq_prev = NULL; | |
449 | struct rb_node *rbnext, *rbprev; | |
450 | ||
b4878f24 | 451 | if (!(rbnext = rb_next(&last->rb_node))) { |
1da177e4 | 452 | rbnext = rb_first(&cfqq->sort_list); |
22e2c507 JA |
453 | if (rbnext == &last->rb_node) |
454 | rbnext = NULL; | |
455 | } | |
1da177e4 LT |
456 | |
457 | rbprev = rb_prev(&last->rb_node); | |
458 | ||
459 | if (rbprev) | |
460 | crq_prev = rb_entry_crq(rbprev); | |
461 | if (rbnext) | |
462 | crq_next = rb_entry_crq(rbnext); | |
463 | ||
464 | return cfq_choose_req(cfqd, crq_next, crq_prev); | |
465 | } | |
466 | ||
467 | static void cfq_update_next_crq(struct cfq_rq *crq) | |
468 | { | |
469 | struct cfq_queue *cfqq = crq->cfq_queue; | |
470 | ||
471 | if (cfqq->next_crq == crq) | |
472 | cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); | |
473 | } | |
474 | ||
22e2c507 | 475 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
1da177e4 | 476 | { |
22e2c507 JA |
477 | struct cfq_data *cfqd = cfqq->cfqd; |
478 | struct list_head *list, *entry; | |
1da177e4 | 479 | |
3b18152c | 480 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 481 | |
22e2c507 | 482 | list_del(&cfqq->cfq_list); |
1da177e4 | 483 | |
22e2c507 JA |
484 | if (cfq_class_rt(cfqq)) |
485 | list = &cfqd->cur_rr; | |
486 | else if (cfq_class_idle(cfqq)) | |
487 | list = &cfqd->idle_rr; | |
488 | else { | |
489 | /* | |
490 | * if cfqq has requests in flight, don't allow it to be | |
491 | * found in cfq_set_active_queue before it has finished them. | |
492 | * this is done to increase fairness between a process that | |
493 | * has lots of io pending vs one that only generates one | |
494 | * sporadically or synchronously | |
495 | */ | |
3b18152c | 496 | if (cfq_cfqq_dispatched(cfqq)) |
22e2c507 JA |
497 | list = &cfqd->busy_rr; |
498 | else | |
499 | list = &cfqd->rr_list[cfqq->ioprio]; | |
1da177e4 LT |
500 | } |
501 | ||
22e2c507 JA |
502 | /* |
503 | * if queue was preempted, just add to front to be fair. busy_rr | |
504 | * isn't sorted. | |
505 | */ | |
506 | if (preempted || list == &cfqd->busy_rr) { | |
507 | list_add(&cfqq->cfq_list, list); | |
1da177e4 | 508 | return; |
22e2c507 | 509 | } |
1da177e4 LT |
510 | |
511 | /* | |
22e2c507 | 512 | * sort by when queue was last serviced |
1da177e4 | 513 | */ |
22e2c507 JA |
514 | entry = list; |
515 | while ((entry = entry->prev) != list) { | |
1da177e4 LT |
516 | struct cfq_queue *__cfqq = list_entry_cfqq(entry); |
517 | ||
22e2c507 JA |
518 | if (!__cfqq->service_last) |
519 | break; | |
520 | if (time_before(__cfqq->service_last, cfqq->service_last)) | |
1da177e4 | 521 | break; |
1da177e4 LT |
522 | } |
523 | ||
524 | list_add(&cfqq->cfq_list, entry); | |
525 | } | |
526 | ||
527 | /* | |
528 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 529 | * the pending list according to last request service |
1da177e4 LT |
530 | */ |
531 | static inline void | |
b4878f24 | 532 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 533 | { |
3b18152c JA |
534 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
535 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
536 | cfqd->busy_queues++; |
537 | ||
b4878f24 | 538 | cfq_resort_rr_list(cfqq, 0); |
1da177e4 LT |
539 | } |
540 | ||
541 | static inline void | |
542 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
543 | { | |
3b18152c JA |
544 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
545 | cfq_clear_cfqq_on_rr(cfqq); | |
22e2c507 | 546 | list_move(&cfqq->cfq_list, &cfqd->empty_list); |
1da177e4 LT |
547 | |
548 | BUG_ON(!cfqd->busy_queues); | |
549 | cfqd->busy_queues--; | |
550 | } | |
551 | ||
552 | /* | |
553 | * rb tree support functions | |
554 | */ | |
555 | static inline void cfq_del_crq_rb(struct cfq_rq *crq) | |
556 | { | |
557 | struct cfq_queue *cfqq = crq->cfq_queue; | |
b4878f24 JA |
558 | struct cfq_data *cfqd = cfqq->cfqd; |
559 | const int sync = cfq_crq_is_sync(crq); | |
1da177e4 | 560 | |
b4878f24 JA |
561 | BUG_ON(!cfqq->queued[sync]); |
562 | cfqq->queued[sync]--; | |
1da177e4 | 563 | |
b4878f24 | 564 | cfq_update_next_crq(crq); |
1da177e4 | 565 | |
b4878f24 JA |
566 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
567 | RB_CLEAR_COLOR(&crq->rb_node); | |
1da177e4 | 568 | |
b4878f24 JA |
569 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list)) |
570 | cfq_del_cfqq_rr(cfqd, cfqq); | |
1da177e4 LT |
571 | } |
572 | ||
573 | static struct cfq_rq * | |
574 | __cfq_add_crq_rb(struct cfq_rq *crq) | |
575 | { | |
576 | struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; | |
577 | struct rb_node *parent = NULL; | |
578 | struct cfq_rq *__crq; | |
579 | ||
580 | while (*p) { | |
581 | parent = *p; | |
582 | __crq = rb_entry_crq(parent); | |
583 | ||
584 | if (crq->rb_key < __crq->rb_key) | |
585 | p = &(*p)->rb_left; | |
586 | else if (crq->rb_key > __crq->rb_key) | |
587 | p = &(*p)->rb_right; | |
588 | else | |
589 | return __crq; | |
590 | } | |
591 | ||
592 | rb_link_node(&crq->rb_node, parent, p); | |
593 | return NULL; | |
594 | } | |
595 | ||
596 | static void cfq_add_crq_rb(struct cfq_rq *crq) | |
597 | { | |
598 | struct cfq_queue *cfqq = crq->cfq_queue; | |
599 | struct cfq_data *cfqd = cfqq->cfqd; | |
600 | struct request *rq = crq->request; | |
601 | struct cfq_rq *__alias; | |
602 | ||
603 | crq->rb_key = rq_rb_key(rq); | |
3b18152c | 604 | cfqq->queued[cfq_crq_is_sync(crq)]++; |
1da177e4 LT |
605 | |
606 | /* | |
607 | * looks a little odd, but the first insert might return an alias. | |
608 | * if that happens, put the alias on the dispatch list | |
609 | */ | |
610 | while ((__alias = __cfq_add_crq_rb(crq)) != NULL) | |
b4878f24 | 611 | cfq_dispatch_insert(cfqd->queue, __alias); |
1da177e4 LT |
612 | |
613 | rb_insert_color(&crq->rb_node, &cfqq->sort_list); | |
614 | ||
3b18152c | 615 | if (!cfq_cfqq_on_rr(cfqq)) |
b4878f24 | 616 | cfq_add_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
617 | |
618 | /* | |
619 | * check if this request is a better next-serve candidate | |
620 | */ | |
621 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
622 | } | |
623 | ||
624 | static inline void | |
625 | cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
626 | { | |
b4878f24 JA |
627 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
628 | cfqq->queued[cfq_crq_is_sync(crq)]--; | |
1da177e4 LT |
629 | |
630 | cfq_add_crq_rb(crq); | |
631 | } | |
632 | ||
206dc69b JA |
633 | static struct request * |
634 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 635 | { |
206dc69b JA |
636 | struct task_struct *tsk = current; |
637 | pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio)); | |
638 | struct cfq_queue *cfqq; | |
1da177e4 | 639 | struct rb_node *n; |
206dc69b | 640 | sector_t sector; |
1da177e4 | 641 | |
206dc69b | 642 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); |
1da177e4 LT |
643 | if (!cfqq) |
644 | goto out; | |
645 | ||
206dc69b | 646 | sector = bio->bi_sector + bio_sectors(bio); |
1da177e4 LT |
647 | n = cfqq->sort_list.rb_node; |
648 | while (n) { | |
649 | struct cfq_rq *crq = rb_entry_crq(n); | |
650 | ||
651 | if (sector < crq->rb_key) | |
652 | n = n->rb_left; | |
653 | else if (sector > crq->rb_key) | |
654 | n = n->rb_right; | |
655 | else | |
656 | return crq->request; | |
657 | } | |
658 | ||
659 | out: | |
660 | return NULL; | |
661 | } | |
662 | ||
b4878f24 | 663 | static void cfq_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 664 | { |
22e2c507 | 665 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 666 | |
b4878f24 | 667 | cfqd->rq_in_driver++; |
25776e35 JA |
668 | |
669 | /* | |
670 | * If the depth is larger 1, it really could be queueing. But lets | |
671 | * make the mark a little higher - idling could still be good for | |
672 | * low queueing, and a low queueing number could also just indicate | |
673 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
674 | */ | |
675 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
676 | cfqd->hw_tag = 1; | |
1da177e4 LT |
677 | } |
678 | ||
b4878f24 | 679 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 680 | { |
b4878f24 JA |
681 | struct cfq_data *cfqd = q->elevator->elevator_data; |
682 | ||
683 | WARN_ON(!cfqd->rq_in_driver); | |
684 | cfqd->rq_in_driver--; | |
1da177e4 LT |
685 | } |
686 | ||
b4878f24 | 687 | static void cfq_remove_request(struct request *rq) |
1da177e4 LT |
688 | { |
689 | struct cfq_rq *crq = RQ_DATA(rq); | |
690 | ||
b4878f24 JA |
691 | list_del_init(&rq->queuelist); |
692 | cfq_del_crq_rb(crq); | |
98b11471 | 693 | cfq_del_crq_hash(crq); |
1da177e4 LT |
694 | } |
695 | ||
696 | static int | |
697 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
698 | { | |
699 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
700 | struct request *__rq; | |
701 | int ret; | |
702 | ||
1da177e4 | 703 | __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); |
22e2c507 JA |
704 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
705 | ret = ELEVATOR_BACK_MERGE; | |
706 | goto out; | |
1da177e4 LT |
707 | } |
708 | ||
206dc69b | 709 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 JA |
710 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
711 | ret = ELEVATOR_FRONT_MERGE; | |
712 | goto out; | |
1da177e4 LT |
713 | } |
714 | ||
715 | return ELEVATOR_NO_MERGE; | |
716 | out: | |
1da177e4 LT |
717 | *req = __rq; |
718 | return ret; | |
719 | } | |
720 | ||
721 | static void cfq_merged_request(request_queue_t *q, struct request *req) | |
722 | { | |
723 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
724 | struct cfq_rq *crq = RQ_DATA(req); | |
725 | ||
726 | cfq_del_crq_hash(crq); | |
727 | cfq_add_crq_hash(cfqd, crq); | |
728 | ||
b4878f24 | 729 | if (rq_rb_key(req) != crq->rb_key) { |
1da177e4 LT |
730 | struct cfq_queue *cfqq = crq->cfq_queue; |
731 | ||
732 | cfq_update_next_crq(crq); | |
733 | cfq_reposition_crq_rb(cfqq, crq); | |
734 | } | |
1da177e4 LT |
735 | } |
736 | ||
737 | static void | |
738 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
739 | struct request *next) | |
740 | { | |
1da177e4 LT |
741 | cfq_merged_request(q, rq); |
742 | ||
22e2c507 JA |
743 | /* |
744 | * reposition in fifo if next is older than rq | |
745 | */ | |
746 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
747 | time_before(next->start_time, rq->start_time)) | |
748 | list_move(&rq->queuelist, &next->queuelist); | |
749 | ||
b4878f24 | 750 | cfq_remove_request(next); |
22e2c507 JA |
751 | } |
752 | ||
753 | static inline void | |
754 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
755 | { | |
756 | if (cfqq) { | |
757 | /* | |
758 | * stop potential idle class queues waiting service | |
759 | */ | |
760 | del_timer(&cfqd->idle_class_timer); | |
761 | ||
762 | cfqq->slice_start = jiffies; | |
763 | cfqq->slice_end = 0; | |
764 | cfqq->slice_left = 0; | |
3b18152c JA |
765 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
766 | cfq_clear_cfqq_fifo_expire(cfqq); | |
22e2c507 JA |
767 | } |
768 | ||
769 | cfqd->active_queue = cfqq; | |
770 | } | |
771 | ||
7b14e3b5 JA |
772 | /* |
773 | * current cfqq expired its slice (or was too idle), select new one | |
774 | */ | |
775 | static void | |
776 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
777 | int preempted) | |
778 | { | |
779 | unsigned long now = jiffies; | |
780 | ||
781 | if (cfq_cfqq_wait_request(cfqq)) | |
782 | del_timer(&cfqd->idle_slice_timer); | |
783 | ||
784 | if (!preempted && !cfq_cfqq_dispatched(cfqq)) { | |
785 | cfqq->service_last = now; | |
786 | cfq_schedule_dispatch(cfqd); | |
787 | } | |
788 | ||
789 | cfq_clear_cfqq_must_dispatch(cfqq); | |
790 | cfq_clear_cfqq_wait_request(cfqq); | |
791 | ||
792 | /* | |
793 | * store what was left of this slice, if the queue idled out | |
794 | * or was preempted | |
795 | */ | |
796 | if (time_after(cfqq->slice_end, now)) | |
797 | cfqq->slice_left = cfqq->slice_end - now; | |
798 | else | |
799 | cfqq->slice_left = 0; | |
800 | ||
801 | if (cfq_cfqq_on_rr(cfqq)) | |
802 | cfq_resort_rr_list(cfqq, preempted); | |
803 | ||
804 | if (cfqq == cfqd->active_queue) | |
805 | cfqd->active_queue = NULL; | |
806 | ||
807 | if (cfqd->active_cic) { | |
808 | put_io_context(cfqd->active_cic->ioc); | |
809 | cfqd->active_cic = NULL; | |
810 | } | |
811 | ||
812 | cfqd->dispatch_slice = 0; | |
813 | } | |
814 | ||
815 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
816 | { | |
817 | struct cfq_queue *cfqq = cfqd->active_queue; | |
818 | ||
819 | if (cfqq) | |
820 | __cfq_slice_expired(cfqd, cfqq, preempted); | |
821 | } | |
822 | ||
22e2c507 JA |
823 | /* |
824 | * 0 | |
825 | * 0,1 | |
826 | * 0,1,2 | |
827 | * 0,1,2,3 | |
828 | * 0,1,2,3,4 | |
829 | * 0,1,2,3,4,5 | |
830 | * 0,1,2,3,4,5,6 | |
831 | * 0,1,2,3,4,5,6,7 | |
832 | */ | |
833 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
834 | { | |
835 | int prio, wrap; | |
836 | ||
837 | prio = -1; | |
838 | wrap = 0; | |
839 | do { | |
840 | int p; | |
841 | ||
842 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
843 | if (!list_empty(&cfqd->rr_list[p])) { | |
844 | prio = p; | |
845 | break; | |
846 | } | |
847 | } | |
848 | ||
849 | if (prio != -1) | |
850 | break; | |
851 | cfqd->cur_prio = 0; | |
852 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
853 | cfqd->cur_end_prio = 0; | |
854 | if (wrap) | |
855 | break; | |
856 | wrap = 1; | |
1da177e4 | 857 | } |
22e2c507 JA |
858 | } while (1); |
859 | ||
860 | if (unlikely(prio == -1)) | |
861 | return -1; | |
862 | ||
863 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
864 | ||
865 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
866 | ||
867 | cfqd->cur_prio = prio + 1; | |
868 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
869 | cfqd->cur_end_prio = cfqd->cur_prio; | |
870 | cfqd->cur_prio = 0; | |
871 | } | |
872 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
873 | cfqd->cur_prio = 0; | |
874 | cfqd->cur_end_prio = 0; | |
1da177e4 LT |
875 | } |
876 | ||
22e2c507 JA |
877 | return prio; |
878 | } | |
879 | ||
3b18152c | 880 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
22e2c507 | 881 | { |
7b14e3b5 | 882 | struct cfq_queue *cfqq = NULL; |
22e2c507 JA |
883 | |
884 | /* | |
885 | * if current list is non-empty, grab first entry. if it is empty, | |
886 | * get next prio level and grab first entry then if any are spliced | |
887 | */ | |
888 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) | |
889 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
890 | ||
e0de0206 JA |
891 | /* |
892 | * If no new queues are available, check if the busy list has some | |
893 | * before falling back to idle io. | |
894 | */ | |
895 | if (!cfqq && !list_empty(&cfqd->busy_rr)) | |
896 | cfqq = list_entry_cfqq(cfqd->busy_rr.next); | |
897 | ||
22e2c507 JA |
898 | /* |
899 | * if we have idle queues and no rt or be queues had pending | |
900 | * requests, either allow immediate service if the grace period | |
901 | * has passed or arm the idle grace timer | |
902 | */ | |
903 | if (!cfqq && !list_empty(&cfqd->idle_rr)) { | |
904 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
905 | ||
906 | if (time_after_eq(jiffies, end)) | |
907 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
908 | else | |
909 | mod_timer(&cfqd->idle_class_timer, end); | |
910 | } | |
911 | ||
912 | __cfq_set_active_queue(cfqd, cfqq); | |
3b18152c | 913 | return cfqq; |
22e2c507 JA |
914 | } |
915 | ||
22e2c507 JA |
916 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
917 | ||
918 | { | |
206dc69b | 919 | struct cfq_io_context *cic; |
7b14e3b5 JA |
920 | unsigned long sl; |
921 | ||
22e2c507 JA |
922 | WARN_ON(!RB_EMPTY(&cfqq->sort_list)); |
923 | WARN_ON(cfqq != cfqd->active_queue); | |
924 | ||
925 | /* | |
926 | * idle is disabled, either manually or by past process history | |
927 | */ | |
928 | if (!cfqd->cfq_slice_idle) | |
929 | return 0; | |
3b18152c | 930 | if (!cfq_cfqq_idle_window(cfqq)) |
22e2c507 JA |
931 | return 0; |
932 | /* | |
933 | * task has exited, don't wait | |
934 | */ | |
206dc69b JA |
935 | cic = cfqd->active_cic; |
936 | if (!cic || !cic->ioc->task) | |
22e2c507 JA |
937 | return 0; |
938 | ||
3b18152c JA |
939 | cfq_mark_cfqq_must_dispatch(cfqq); |
940 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 941 | |
7b14e3b5 | 942 | sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); |
206dc69b JA |
943 | |
944 | /* | |
945 | * we don't want to idle for seeks, but we do want to allow | |
946 | * fair distribution of slice time for a process doing back-to-back | |
947 | * seeks. so allow a little bit of time for him to submit a new rq | |
948 | */ | |
949 | if (sample_valid(cic->seek_samples) && cic->seek_mean > 131072) | |
950 | sl = 2; | |
951 | ||
7b14e3b5 | 952 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
22e2c507 | 953 | return 1; |
1da177e4 LT |
954 | } |
955 | ||
b4878f24 | 956 | static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) |
1da177e4 LT |
957 | { |
958 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
959 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 JA |
960 | |
961 | cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); | |
b4878f24 | 962 | cfq_remove_request(crq->request); |
3b18152c | 963 | cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; |
b4878f24 | 964 | elv_dispatch_sort(q, crq->request); |
1da177e4 LT |
965 | } |
966 | ||
967 | /* | |
968 | * return expired entry, or NULL to just start from scratch in rbtree | |
969 | */ | |
970 | static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) | |
971 | { | |
972 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 973 | struct request *rq; |
1da177e4 LT |
974 | struct cfq_rq *crq; |
975 | ||
3b18152c | 976 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 LT |
977 | return NULL; |
978 | ||
22e2c507 | 979 | if (!list_empty(&cfqq->fifo)) { |
3b18152c | 980 | int fifo = cfq_cfqq_class_sync(cfqq); |
1da177e4 | 981 | |
22e2c507 JA |
982 | crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); |
983 | rq = crq->request; | |
984 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
3b18152c | 985 | cfq_mark_cfqq_fifo_expire(cfqq); |
22e2c507 JA |
986 | return crq; |
987 | } | |
1da177e4 LT |
988 | } |
989 | ||
990 | return NULL; | |
991 | } | |
992 | ||
993 | /* | |
3b18152c JA |
994 | * Scale schedule slice based on io priority. Use the sync time slice only |
995 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
996 | * io only, should not get full sync slice length. | |
1da177e4 | 997 | */ |
22e2c507 JA |
998 | static inline int |
999 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1000 | { | |
1001 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
1002 | ||
1003 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
1004 | ||
1005 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
1006 | } | |
1007 | ||
1da177e4 | 1008 | static inline void |
22e2c507 | 1009 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1010 | { |
22e2c507 JA |
1011 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
1012 | } | |
1da177e4 | 1013 | |
22e2c507 JA |
1014 | static inline int |
1015 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1016 | { | |
1017 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1018 | |
22e2c507 | 1019 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1020 | |
22e2c507 | 1021 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1022 | } |
1023 | ||
22e2c507 JA |
1024 | /* |
1025 | * get next queue for service | |
1026 | */ | |
1b5ed5e1 | 1027 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1028 | { |
22e2c507 | 1029 | unsigned long now = jiffies; |
1da177e4 | 1030 | struct cfq_queue *cfqq; |
1da177e4 | 1031 | |
22e2c507 JA |
1032 | cfqq = cfqd->active_queue; |
1033 | if (!cfqq) | |
1034 | goto new_queue; | |
1da177e4 | 1035 | |
22e2c507 JA |
1036 | /* |
1037 | * slice has expired | |
1038 | */ | |
3b18152c JA |
1039 | if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) |
1040 | goto expire; | |
1da177e4 | 1041 | |
22e2c507 JA |
1042 | /* |
1043 | * if queue has requests, dispatch one. if not, check if | |
1044 | * enough slice is left to wait for one | |
1045 | */ | |
1046 | if (!RB_EMPTY(&cfqq->sort_list)) | |
1047 | goto keep_queue; | |
1b5ed5e1 | 1048 | else if (cfq_cfqq_class_sync(cfqq) && |
22e2c507 JA |
1049 | time_before(now, cfqq->slice_end)) { |
1050 | if (cfq_arm_slice_timer(cfqd, cfqq)) | |
1051 | return NULL; | |
1052 | } | |
1053 | ||
3b18152c | 1054 | expire: |
22e2c507 | 1055 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
1056 | new_queue: |
1057 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 1058 | keep_queue: |
3b18152c | 1059 | return cfqq; |
22e2c507 JA |
1060 | } |
1061 | ||
1062 | static int | |
1063 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1064 | int max_dispatch) | |
1065 | { | |
1066 | int dispatched = 0; | |
1067 | ||
1068 | BUG_ON(RB_EMPTY(&cfqq->sort_list)); | |
1069 | ||
1070 | do { | |
1071 | struct cfq_rq *crq; | |
1da177e4 LT |
1072 | |
1073 | /* | |
22e2c507 | 1074 | * follow expired path, else get first next available |
1da177e4 | 1075 | */ |
22e2c507 JA |
1076 | if ((crq = cfq_check_fifo(cfqq)) == NULL) |
1077 | crq = cfqq->next_crq; | |
1078 | ||
1079 | /* | |
1080 | * finally, insert request into driver dispatch list | |
1081 | */ | |
b4878f24 | 1082 | cfq_dispatch_insert(cfqd->queue, crq); |
1da177e4 | 1083 | |
22e2c507 JA |
1084 | cfqd->dispatch_slice++; |
1085 | dispatched++; | |
1da177e4 | 1086 | |
22e2c507 JA |
1087 | if (!cfqd->active_cic) { |
1088 | atomic_inc(&crq->io_context->ioc->refcount); | |
1089 | cfqd->active_cic = crq->io_context; | |
1090 | } | |
1da177e4 | 1091 | |
22e2c507 JA |
1092 | if (RB_EMPTY(&cfqq->sort_list)) |
1093 | break; | |
1094 | ||
1095 | } while (dispatched < max_dispatch); | |
1096 | ||
1097 | /* | |
1098 | * if slice end isn't set yet, set it. if at least one request was | |
1099 | * sync, use the sync time slice value | |
1100 | */ | |
1101 | if (!cfqq->slice_end) | |
1102 | cfq_set_prio_slice(cfqd, cfqq); | |
1103 | ||
1104 | /* | |
1105 | * expire an async queue immediately if it has used up its slice. idle | |
1106 | * queue always expire after 1 dispatch round. | |
1107 | */ | |
1108 | if ((!cfq_cfqq_sync(cfqq) && | |
1109 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1110 | cfq_class_idle(cfqq)) | |
1111 | cfq_slice_expired(cfqd, 0); | |
1112 | ||
1113 | return dispatched; | |
1114 | } | |
1115 | ||
1b5ed5e1 TH |
1116 | static int |
1117 | cfq_forced_dispatch_cfqqs(struct list_head *list) | |
1118 | { | |
1119 | int dispatched = 0; | |
1120 | struct cfq_queue *cfqq, *next; | |
1121 | struct cfq_rq *crq; | |
1122 | ||
1123 | list_for_each_entry_safe(cfqq, next, list, cfq_list) { | |
1124 | while ((crq = cfqq->next_crq)) { | |
1125 | cfq_dispatch_insert(cfqq->cfqd->queue, crq); | |
1126 | dispatched++; | |
1127 | } | |
1128 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1129 | } | |
1130 | return dispatched; | |
1131 | } | |
1132 | ||
1133 | static int | |
1134 | cfq_forced_dispatch(struct cfq_data *cfqd) | |
1135 | { | |
1136 | int i, dispatched = 0; | |
1137 | ||
1138 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
1139 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]); | |
1140 | ||
1141 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr); | |
1142 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); | |
1143 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
1144 | ||
1145 | cfq_slice_expired(cfqd, 0); | |
1146 | ||
1147 | BUG_ON(cfqd->busy_queues); | |
1148 | ||
1149 | return dispatched; | |
1150 | } | |
1151 | ||
22e2c507 | 1152 | static int |
b4878f24 | 1153 | cfq_dispatch_requests(request_queue_t *q, int force) |
22e2c507 JA |
1154 | { |
1155 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1156 | struct cfq_queue *cfqq; | |
1157 | ||
1158 | if (!cfqd->busy_queues) | |
1159 | return 0; | |
1160 | ||
1b5ed5e1 TH |
1161 | if (unlikely(force)) |
1162 | return cfq_forced_dispatch(cfqd); | |
1163 | ||
1164 | cfqq = cfq_select_queue(cfqd); | |
22e2c507 | 1165 | if (cfqq) { |
b4878f24 JA |
1166 | int max_dispatch; |
1167 | ||
3b18152c JA |
1168 | cfq_clear_cfqq_must_dispatch(cfqq); |
1169 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1170 | del_timer(&cfqd->idle_slice_timer); |
1171 | ||
1b5ed5e1 TH |
1172 | max_dispatch = cfqd->cfq_quantum; |
1173 | if (cfq_class_idle(cfqq)) | |
1174 | max_dispatch = 1; | |
1da177e4 | 1175 | |
22e2c507 | 1176 | return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1177 | } |
1178 | ||
22e2c507 | 1179 | return 0; |
1da177e4 LT |
1180 | } |
1181 | ||
1da177e4 LT |
1182 | /* |
1183 | * task holds one reference to the queue, dropped when task exits. each crq | |
1184 | * in-flight on this queue also holds a reference, dropped when crq is freed. | |
1185 | * | |
1186 | * queue lock must be held here. | |
1187 | */ | |
1188 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1189 | { | |
22e2c507 JA |
1190 | struct cfq_data *cfqd = cfqq->cfqd; |
1191 | ||
1192 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1193 | |
1194 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1195 | return; | |
1196 | ||
1197 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1198 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1199 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1200 | |
7b14e3b5 | 1201 | if (unlikely(cfqd->active_queue == cfqq)) |
3b18152c | 1202 | __cfq_slice_expired(cfqd, cfqq, 0); |
22e2c507 | 1203 | |
1da177e4 LT |
1204 | /* |
1205 | * it's on the empty list and still hashed | |
1206 | */ | |
1207 | list_del(&cfqq->cfq_list); | |
1208 | hlist_del(&cfqq->cfq_hash); | |
1209 | kmem_cache_free(cfq_pool, cfqq); | |
1210 | } | |
1211 | ||
1212 | static inline struct cfq_queue * | |
3b18152c JA |
1213 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, |
1214 | const int hashval) | |
1da177e4 LT |
1215 | { |
1216 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
206dc69b JA |
1217 | struct hlist_node *entry; |
1218 | struct cfq_queue *__cfqq; | |
1da177e4 | 1219 | |
206dc69b | 1220 | hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) { |
b0a6916b | 1221 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); |
1da177e4 | 1222 | |
206dc69b | 1223 | if (__cfqq->key == key && (__p == prio || !prio)) |
1da177e4 LT |
1224 | return __cfqq; |
1225 | } | |
1226 | ||
1227 | return NULL; | |
1228 | } | |
1229 | ||
1230 | static struct cfq_queue * | |
3b18152c | 1231 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) |
1da177e4 | 1232 | { |
3b18152c | 1233 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); |
1da177e4 LT |
1234 | } |
1235 | ||
e2d74ac0 | 1236 | static void cfq_free_io_context(struct io_context *ioc) |
1da177e4 | 1237 | { |
22e2c507 | 1238 | struct cfq_io_context *__cic; |
e2d74ac0 JA |
1239 | struct rb_node *n; |
1240 | int freed = 0; | |
1da177e4 | 1241 | |
e2d74ac0 JA |
1242 | while ((n = rb_first(&ioc->cic_root)) != NULL) { |
1243 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1244 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
22e2c507 | 1245 | kmem_cache_free(cfq_ioc_pool, __cic); |
334e94de | 1246 | freed++; |
1da177e4 LT |
1247 | } |
1248 | ||
334e94de AV |
1249 | if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone) |
1250 | complete(ioc_gone); | |
1da177e4 LT |
1251 | } |
1252 | ||
e17a9489 AV |
1253 | static void cfq_trim(struct io_context *ioc) |
1254 | { | |
1255 | ioc->set_ioprio = NULL; | |
e2d74ac0 | 1256 | cfq_free_io_context(ioc); |
e17a9489 AV |
1257 | } |
1258 | ||
22e2c507 JA |
1259 | /* |
1260 | * Called with interrupts disabled | |
1261 | */ | |
1262 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1da177e4 | 1263 | { |
478a82b0 | 1264 | struct cfq_data *cfqd = cic->key; |
d9ff4187 AV |
1265 | request_queue_t *q; |
1266 | ||
1267 | if (!cfqd) | |
1268 | return; | |
1269 | ||
1270 | q = cfqd->queue; | |
22e2c507 JA |
1271 | |
1272 | WARN_ON(!irqs_disabled()); | |
1273 | ||
1274 | spin_lock(q->queue_lock); | |
1275 | ||
12a05732 AV |
1276 | if (cic->cfqq[ASYNC]) { |
1277 | if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue)) | |
1278 | __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0); | |
1279 | cfq_put_queue(cic->cfqq[ASYNC]); | |
1280 | cic->cfqq[ASYNC] = NULL; | |
1281 | } | |
1282 | ||
1283 | if (cic->cfqq[SYNC]) { | |
1284 | if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue)) | |
1285 | __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0); | |
1286 | cfq_put_queue(cic->cfqq[SYNC]); | |
1287 | cic->cfqq[SYNC] = NULL; | |
1288 | } | |
22e2c507 | 1289 | |
478a82b0 | 1290 | cic->key = NULL; |
d9ff4187 | 1291 | list_del_init(&cic->queue_list); |
22e2c507 | 1292 | spin_unlock(q->queue_lock); |
1da177e4 LT |
1293 | } |
1294 | ||
e2d74ac0 | 1295 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1296 | { |
22e2c507 | 1297 | struct cfq_io_context *__cic; |
1da177e4 | 1298 | unsigned long flags; |
e2d74ac0 | 1299 | struct rb_node *n; |
22e2c507 | 1300 | |
1da177e4 LT |
1301 | /* |
1302 | * put the reference this task is holding to the various queues | |
1303 | */ | |
3793c65c | 1304 | spin_lock_irqsave(&cfq_exit_lock, flags); |
e2d74ac0 JA |
1305 | |
1306 | n = rb_first(&ioc->cic_root); | |
1307 | while (n != NULL) { | |
1308 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1309 | ||
22e2c507 | 1310 | cfq_exit_single_io_context(__cic); |
e2d74ac0 | 1311 | n = rb_next(n); |
1da177e4 LT |
1312 | } |
1313 | ||
3793c65c | 1314 | spin_unlock_irqrestore(&cfq_exit_lock, flags); |
1da177e4 LT |
1315 | } |
1316 | ||
22e2c507 | 1317 | static struct cfq_io_context * |
8267e268 | 1318 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1319 | { |
22e2c507 | 1320 | struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); |
1da177e4 LT |
1321 | |
1322 | if (cic) { | |
e2d74ac0 JA |
1323 | RB_CLEAR(&cic->rb_node); |
1324 | cic->key = NULL; | |
12a05732 AV |
1325 | cic->cfqq[ASYNC] = NULL; |
1326 | cic->cfqq[SYNC] = NULL; | |
22e2c507 JA |
1327 | cic->last_end_request = jiffies; |
1328 | cic->ttime_total = 0; | |
1329 | cic->ttime_samples = 0; | |
1330 | cic->ttime_mean = 0; | |
1331 | cic->dtor = cfq_free_io_context; | |
1332 | cic->exit = cfq_exit_io_context; | |
d9ff4187 | 1333 | INIT_LIST_HEAD(&cic->queue_list); |
334e94de | 1334 | atomic_inc(&ioc_count); |
1da177e4 LT |
1335 | } |
1336 | ||
1337 | return cic; | |
1338 | } | |
1339 | ||
22e2c507 JA |
1340 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1341 | { | |
1342 | struct task_struct *tsk = current; | |
1343 | int ioprio_class; | |
1344 | ||
3b18152c | 1345 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1346 | return; |
1347 | ||
1348 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1349 | switch (ioprio_class) { | |
1350 | default: | |
1351 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1352 | case IOPRIO_CLASS_NONE: | |
1353 | /* | |
1354 | * no prio set, place us in the middle of the BE classes | |
1355 | */ | |
1356 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1357 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1358 | break; | |
1359 | case IOPRIO_CLASS_RT: | |
1360 | cfqq->ioprio = task_ioprio(tsk); | |
1361 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1362 | break; | |
1363 | case IOPRIO_CLASS_BE: | |
1364 | cfqq->ioprio = task_ioprio(tsk); | |
1365 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1366 | break; | |
1367 | case IOPRIO_CLASS_IDLE: | |
1368 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1369 | cfqq->ioprio = 7; | |
3b18152c | 1370 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1371 | break; |
1372 | } | |
1373 | ||
1374 | /* | |
1375 | * keep track of original prio settings in case we have to temporarily | |
1376 | * elevate the priority of this queue | |
1377 | */ | |
1378 | cfqq->org_ioprio = cfqq->ioprio; | |
1379 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1380 | ||
3b18152c | 1381 | if (cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1382 | cfq_resort_rr_list(cfqq, 0); |
1383 | ||
3b18152c | 1384 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1385 | } |
1386 | ||
478a82b0 | 1387 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1388 | { |
478a82b0 AV |
1389 | struct cfq_data *cfqd = cic->key; |
1390 | struct cfq_queue *cfqq; | |
1391 | if (cfqd) { | |
22e2c507 | 1392 | spin_lock(cfqd->queue->queue_lock); |
12a05732 AV |
1393 | cfqq = cic->cfqq[ASYNC]; |
1394 | if (cfqq) { | |
6f325a13 AV |
1395 | struct cfq_queue *new_cfqq; |
1396 | new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC, | |
1397 | cic->ioc->task, GFP_ATOMIC); | |
1398 | if (new_cfqq) { | |
1399 | cic->cfqq[ASYNC] = new_cfqq; | |
1400 | cfq_put_queue(cfqq); | |
1401 | } | |
12a05732 AV |
1402 | } |
1403 | cfqq = cic->cfqq[SYNC]; | |
478a82b0 AV |
1404 | if (cfqq) { |
1405 | cfq_mark_cfqq_prio_changed(cfqq); | |
1406 | cfq_init_prio_data(cfqq); | |
1407 | } | |
22e2c507 JA |
1408 | spin_unlock(cfqd->queue->queue_lock); |
1409 | } | |
1410 | } | |
1411 | ||
1412 | /* | |
1413 | * callback from sys_ioprio_set, irqs are disabled | |
1414 | */ | |
1415 | static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) | |
1416 | { | |
a6a0763a | 1417 | struct cfq_io_context *cic; |
e2d74ac0 | 1418 | struct rb_node *n; |
a6a0763a | 1419 | |
3793c65c | 1420 | spin_lock(&cfq_exit_lock); |
a6a0763a | 1421 | |
e2d74ac0 JA |
1422 | n = rb_first(&ioc->cic_root); |
1423 | while (n != NULL) { | |
1424 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
3793c65c | 1425 | |
478a82b0 | 1426 | changed_ioprio(cic); |
e2d74ac0 JA |
1427 | n = rb_next(n); |
1428 | } | |
22e2c507 | 1429 | |
3793c65c | 1430 | spin_unlock(&cfq_exit_lock); |
a6a0763a | 1431 | |
22e2c507 JA |
1432 | return 0; |
1433 | } | |
1434 | ||
1435 | static struct cfq_queue * | |
6f325a13 | 1436 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, |
8267e268 | 1437 | gfp_t gfp_mask) |
22e2c507 JA |
1438 | { |
1439 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1440 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
6f325a13 | 1441 | unsigned short ioprio; |
22e2c507 JA |
1442 | |
1443 | retry: | |
6f325a13 | 1444 | ioprio = tsk->ioprio; |
3b18152c | 1445 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); |
22e2c507 JA |
1446 | |
1447 | if (!cfqq) { | |
1448 | if (new_cfqq) { | |
1449 | cfqq = new_cfqq; | |
1450 | new_cfqq = NULL; | |
1451 | } else if (gfp_mask & __GFP_WAIT) { | |
1452 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1453 | new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1454 | spin_lock_irq(cfqd->queue->queue_lock); | |
1455 | goto retry; | |
1456 | } else { | |
1457 | cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1458 | if (!cfqq) | |
1459 | goto out; | |
1460 | } | |
1461 | ||
1462 | memset(cfqq, 0, sizeof(*cfqq)); | |
1463 | ||
1464 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1465 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
1466 | RB_CLEAR_ROOT(&cfqq->sort_list); | |
1467 | INIT_LIST_HEAD(&cfqq->fifo); | |
1468 | ||
1469 | cfqq->key = key; | |
1470 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1471 | atomic_set(&cfqq->ref, 0); | |
1472 | cfqq->cfqd = cfqd; | |
22e2c507 JA |
1473 | cfqq->service_last = 0; |
1474 | /* | |
1475 | * set ->slice_left to allow preemption for a new process | |
1476 | */ | |
1477 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
25776e35 JA |
1478 | if (!cfqd->hw_tag) |
1479 | cfq_mark_cfqq_idle_window(cfqq); | |
3b18152c JA |
1480 | cfq_mark_cfqq_prio_changed(cfqq); |
1481 | cfq_init_prio_data(cfqq); | |
22e2c507 JA |
1482 | } |
1483 | ||
1484 | if (new_cfqq) | |
1485 | kmem_cache_free(cfq_pool, new_cfqq); | |
1486 | ||
1487 | atomic_inc(&cfqq->ref); | |
1488 | out: | |
1489 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1490 | return cfqq; | |
1491 | } | |
1492 | ||
dbecf3ab OH |
1493 | static void |
1494 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1495 | { | |
3793c65c | 1496 | spin_lock(&cfq_exit_lock); |
dbecf3ab | 1497 | rb_erase(&cic->rb_node, &ioc->cic_root); |
3793c65c JA |
1498 | list_del_init(&cic->queue_list); |
1499 | spin_unlock(&cfq_exit_lock); | |
dbecf3ab OH |
1500 | kmem_cache_free(cfq_ioc_pool, cic); |
1501 | atomic_dec(&ioc_count); | |
1502 | } | |
1503 | ||
e2d74ac0 JA |
1504 | static struct cfq_io_context * |
1505 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1506 | { | |
dbecf3ab | 1507 | struct rb_node *n; |
e2d74ac0 | 1508 | struct cfq_io_context *cic; |
be3b0753 | 1509 | void *k, *key = cfqd; |
e2d74ac0 | 1510 | |
dbecf3ab OH |
1511 | restart: |
1512 | n = ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1513 | while (n) { |
1514 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1515 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1516 | k = cic->key; | |
1517 | if (unlikely(!k)) { | |
dbecf3ab OH |
1518 | cfq_drop_dead_cic(ioc, cic); |
1519 | goto restart; | |
1520 | } | |
e2d74ac0 | 1521 | |
be3b0753 | 1522 | if (key < k) |
e2d74ac0 | 1523 | n = n->rb_left; |
be3b0753 | 1524 | else if (key > k) |
e2d74ac0 JA |
1525 | n = n->rb_right; |
1526 | else | |
1527 | return cic; | |
1528 | } | |
1529 | ||
1530 | return NULL; | |
1531 | } | |
1532 | ||
1533 | static inline void | |
1534 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1535 | struct cfq_io_context *cic) | |
1536 | { | |
dbecf3ab OH |
1537 | struct rb_node **p; |
1538 | struct rb_node *parent; | |
e2d74ac0 | 1539 | struct cfq_io_context *__cic; |
be3b0753 | 1540 | void *k; |
e2d74ac0 | 1541 | |
e2d74ac0 JA |
1542 | cic->ioc = ioc; |
1543 | cic->key = cfqd; | |
1544 | ||
1545 | ioc->set_ioprio = cfq_ioc_set_ioprio; | |
dbecf3ab OH |
1546 | restart: |
1547 | parent = NULL; | |
1548 | p = &ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1549 | while (*p) { |
1550 | parent = *p; | |
1551 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1552 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1553 | k = __cic->key; | |
1554 | if (unlikely(!k)) { | |
dbecf3ab OH |
1555 | cfq_drop_dead_cic(ioc, cic); |
1556 | goto restart; | |
1557 | } | |
e2d74ac0 | 1558 | |
be3b0753 | 1559 | if (cic->key < k) |
e2d74ac0 | 1560 | p = &(*p)->rb_left; |
be3b0753 | 1561 | else if (cic->key > k) |
e2d74ac0 JA |
1562 | p = &(*p)->rb_right; |
1563 | else | |
1564 | BUG(); | |
1565 | } | |
1566 | ||
3793c65c | 1567 | spin_lock(&cfq_exit_lock); |
e2d74ac0 JA |
1568 | rb_link_node(&cic->rb_node, parent, p); |
1569 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
1570 | list_add(&cic->queue_list, &cfqd->cic_list); | |
3793c65c | 1571 | spin_unlock(&cfq_exit_lock); |
e2d74ac0 JA |
1572 | } |
1573 | ||
1da177e4 LT |
1574 | /* |
1575 | * Setup general io context and cfq io context. There can be several cfq | |
1576 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1577 | * than one device managed by cfq. |
1da177e4 LT |
1578 | */ |
1579 | static struct cfq_io_context * | |
e2d74ac0 | 1580 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1581 | { |
22e2c507 | 1582 | struct io_context *ioc = NULL; |
1da177e4 | 1583 | struct cfq_io_context *cic; |
1da177e4 | 1584 | |
22e2c507 | 1585 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1586 | |
22e2c507 | 1587 | ioc = get_io_context(gfp_mask); |
1da177e4 LT |
1588 | if (!ioc) |
1589 | return NULL; | |
1590 | ||
e2d74ac0 JA |
1591 | cic = cfq_cic_rb_lookup(cfqd, ioc); |
1592 | if (cic) | |
1593 | goto out; | |
1da177e4 | 1594 | |
e2d74ac0 JA |
1595 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1596 | if (cic == NULL) | |
1597 | goto err; | |
1da177e4 | 1598 | |
e2d74ac0 | 1599 | cfq_cic_link(cfqd, ioc, cic); |
1da177e4 | 1600 | out: |
1da177e4 LT |
1601 | return cic; |
1602 | err: | |
1603 | put_io_context(ioc); | |
1604 | return NULL; | |
1605 | } | |
1606 | ||
22e2c507 JA |
1607 | static void |
1608 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1609 | { |
22e2c507 | 1610 | unsigned long elapsed, ttime; |
1da177e4 | 1611 | |
22e2c507 JA |
1612 | /* |
1613 | * if this context already has stuff queued, thinktime is from | |
1614 | * last queue not last end | |
1615 | */ | |
1616 | #if 0 | |
1617 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1618 | elapsed = jiffies - cic->last_end_request; | |
1619 | else | |
1620 | elapsed = jiffies - cic->last_queue; | |
1621 | #else | |
1622 | elapsed = jiffies - cic->last_end_request; | |
1623 | #endif | |
1da177e4 | 1624 | |
22e2c507 | 1625 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
db3b5848 | 1626 | |
22e2c507 JA |
1627 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1628 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1629 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1630 | } | |
1da177e4 | 1631 | |
206dc69b JA |
1632 | static void |
1633 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
1634 | struct cfq_rq *crq) | |
1635 | { | |
1636 | sector_t sdist; | |
1637 | u64 total; | |
1638 | ||
1639 | if (cic->last_request_pos < crq->request->sector) | |
1640 | sdist = crq->request->sector - cic->last_request_pos; | |
1641 | else | |
1642 | sdist = cic->last_request_pos - crq->request->sector; | |
1643 | ||
1644 | /* | |
1645 | * Don't allow the seek distance to get too large from the | |
1646 | * odd fragment, pagein, etc | |
1647 | */ | |
1648 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1649 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1650 | else | |
1651 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1652 | ||
1653 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1654 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1655 | total = cic->seek_total + (cic->seek_samples/2); | |
1656 | do_div(total, cic->seek_samples); | |
1657 | cic->seek_mean = (sector_t)total; | |
1658 | } | |
1da177e4 | 1659 | |
22e2c507 JA |
1660 | /* |
1661 | * Disable idle window if the process thinks too long or seeks so much that | |
1662 | * it doesn't matter | |
1663 | */ | |
1664 | static void | |
1665 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1666 | struct cfq_io_context *cic) | |
1667 | { | |
3b18152c | 1668 | int enable_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1669 | |
25776e35 | 1670 | if (!cic->ioc->task || !cfqd->cfq_slice_idle || cfqd->hw_tag) |
22e2c507 JA |
1671 | enable_idle = 0; |
1672 | else if (sample_valid(cic->ttime_samples)) { | |
1673 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1674 | enable_idle = 0; | |
1675 | else | |
1676 | enable_idle = 1; | |
1da177e4 LT |
1677 | } |
1678 | ||
3b18152c JA |
1679 | if (enable_idle) |
1680 | cfq_mark_cfqq_idle_window(cfqq); | |
1681 | else | |
1682 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1683 | } |
1da177e4 | 1684 | |
22e2c507 JA |
1685 | |
1686 | /* | |
1687 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1688 | * no or if we aren't sure, a 1 will cause a preempt. | |
1689 | */ | |
1690 | static int | |
1691 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1692 | struct cfq_rq *crq) | |
1693 | { | |
1694 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1695 | ||
1696 | if (cfq_class_idle(new_cfqq)) | |
1697 | return 0; | |
1698 | ||
1699 | if (!cfqq) | |
1700 | return 1; | |
1701 | ||
1702 | if (cfq_class_idle(cfqq)) | |
1703 | return 1; | |
3b18152c | 1704 | if (!cfq_cfqq_wait_request(new_cfqq)) |
22e2c507 JA |
1705 | return 0; |
1706 | /* | |
1707 | * if it doesn't have slice left, forget it | |
1708 | */ | |
1709 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1710 | return 0; | |
3b18152c | 1711 | if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 JA |
1712 | return 1; |
1713 | ||
1714 | return 0; | |
1715 | } | |
1716 | ||
1717 | /* | |
1718 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1719 | * let it have half of its nominal slice. | |
1720 | */ | |
1721 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1722 | { | |
1723 | struct cfq_queue *__cfqq, *next; | |
1724 | ||
1725 | list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) | |
1726 | cfq_resort_rr_list(__cfqq, 1); | |
1727 | ||
1728 | if (!cfqq->slice_left) | |
1729 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1730 | ||
1731 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
3b18152c | 1732 | __cfq_slice_expired(cfqd, cfqq, 1); |
22e2c507 JA |
1733 | __cfq_set_active_queue(cfqd, cfqq); |
1734 | } | |
1735 | ||
1736 | /* | |
1737 | * should really be a ll_rw_blk.c helper | |
1738 | */ | |
1739 | static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1740 | { | |
1741 | request_queue_t *q = cfqd->queue; | |
1742 | ||
1743 | if (!blk_queue_plugged(q)) | |
1744 | q->request_fn(q); | |
1745 | else | |
1746 | __generic_unplug_device(q); | |
1747 | } | |
1748 | ||
1749 | /* | |
1750 | * Called when a new fs request (crq) is added (to cfqq). Check if there's | |
1751 | * something we should do about it | |
1752 | */ | |
1753 | static void | |
1754 | cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1755 | struct cfq_rq *crq) | |
1756 | { | |
9c2c38a1 | 1757 | struct cfq_io_context *cic; |
22e2c507 JA |
1758 | |
1759 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
1760 | ||
12e9fddd JA |
1761 | cic = crq->io_context; |
1762 | ||
9c2c38a1 JA |
1763 | /* |
1764 | * we never wait for an async request and we don't allow preemption | |
1765 | * of an async request. so just return early | |
1766 | */ | |
12e9fddd JA |
1767 | if (!cfq_crq_is_sync(crq)) { |
1768 | /* | |
1769 | * sync process issued an async request, if it's waiting | |
1770 | * then expire it and kick rq handling. | |
1771 | */ | |
1772 | if (cic == cfqd->active_cic && | |
1773 | del_timer(&cfqd->idle_slice_timer)) { | |
1774 | cfq_slice_expired(cfqd, 0); | |
1775 | cfq_start_queueing(cfqd, cfqq); | |
1776 | } | |
9c2c38a1 | 1777 | return; |
12e9fddd | 1778 | } |
22e2c507 | 1779 | |
9c2c38a1 | 1780 | cfq_update_io_thinktime(cfqd, cic); |
206dc69b | 1781 | cfq_update_io_seektime(cfqd, cic, crq); |
9c2c38a1 JA |
1782 | cfq_update_idle_window(cfqd, cfqq, cic); |
1783 | ||
1784 | cic->last_queue = jiffies; | |
206dc69b | 1785 | cic->last_request_pos = crq->request->sector + crq->request->nr_sectors; |
22e2c507 JA |
1786 | |
1787 | if (cfqq == cfqd->active_queue) { | |
1788 | /* | |
1789 | * if we are waiting for a request for this queue, let it rip | |
1790 | * immediately and flag that we must not expire this queue | |
1791 | * just now | |
1792 | */ | |
3b18152c JA |
1793 | if (cfq_cfqq_wait_request(cfqq)) { |
1794 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 JA |
1795 | del_timer(&cfqd->idle_slice_timer); |
1796 | cfq_start_queueing(cfqd, cfqq); | |
1797 | } | |
1798 | } else if (cfq_should_preempt(cfqd, cfqq, crq)) { | |
1799 | /* | |
1800 | * not the active queue - expire current slice if it is | |
1801 | * idle and has expired it's mean thinktime or this new queue | |
1802 | * has some old slice time left and is of higher priority | |
1803 | */ | |
1804 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1805 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
1806 | cfq_start_queueing(cfqd, cfqq); |
1807 | } | |
1da177e4 LT |
1808 | } |
1809 | ||
b4878f24 | 1810 | static void cfq_insert_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1811 | { |
b4878f24 | 1812 | struct cfq_data *cfqd = q->elevator->elevator_data; |
22e2c507 JA |
1813 | struct cfq_rq *crq = RQ_DATA(rq); |
1814 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1815 | ||
1816 | cfq_init_prio_data(cfqq); | |
1da177e4 LT |
1817 | |
1818 | cfq_add_crq_rb(crq); | |
1da177e4 | 1819 | |
22e2c507 JA |
1820 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1821 | ||
98b11471 | 1822 | if (rq_mergeable(rq)) |
22e2c507 JA |
1823 | cfq_add_crq_hash(cfqd, crq); |
1824 | ||
22e2c507 | 1825 | cfq_crq_enqueued(cfqd, cfqq, crq); |
1da177e4 LT |
1826 | } |
1827 | ||
1da177e4 LT |
1828 | static void cfq_completed_request(request_queue_t *q, struct request *rq) |
1829 | { | |
1830 | struct cfq_rq *crq = RQ_DATA(rq); | |
b4878f24 JA |
1831 | struct cfq_queue *cfqq = crq->cfq_queue; |
1832 | struct cfq_data *cfqd = cfqq->cfqd; | |
1833 | const int sync = cfq_crq_is_sync(crq); | |
1834 | unsigned long now; | |
1da177e4 | 1835 | |
b4878f24 | 1836 | now = jiffies; |
1da177e4 | 1837 | |
b4878f24 JA |
1838 | WARN_ON(!cfqd->rq_in_driver); |
1839 | WARN_ON(!cfqq->on_dispatch[sync]); | |
1840 | cfqd->rq_in_driver--; | |
1841 | cfqq->on_dispatch[sync]--; | |
1da177e4 | 1842 | |
b4878f24 JA |
1843 | if (!cfq_class_idle(cfqq)) |
1844 | cfqd->last_end_request = now; | |
3b18152c | 1845 | |
b4878f24 JA |
1846 | if (!cfq_cfqq_dispatched(cfqq)) { |
1847 | if (cfq_cfqq_on_rr(cfqq)) { | |
1848 | cfqq->service_last = now; | |
1849 | cfq_resort_rr_list(cfqq, 0); | |
1850 | } | |
7b14e3b5 | 1851 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1852 | } |
1853 | ||
b4878f24 JA |
1854 | if (cfq_crq_is_sync(crq)) |
1855 | crq->io_context->last_end_request = now; | |
1da177e4 LT |
1856 | } |
1857 | ||
1858 | static struct request * | |
1859 | cfq_former_request(request_queue_t *q, struct request *rq) | |
1860 | { | |
1861 | struct cfq_rq *crq = RQ_DATA(rq); | |
1862 | struct rb_node *rbprev = rb_prev(&crq->rb_node); | |
1863 | ||
1864 | if (rbprev) | |
1865 | return rb_entry_crq(rbprev)->request; | |
1866 | ||
1867 | return NULL; | |
1868 | } | |
1869 | ||
1870 | static struct request * | |
1871 | cfq_latter_request(request_queue_t *q, struct request *rq) | |
1872 | { | |
1873 | struct cfq_rq *crq = RQ_DATA(rq); | |
1874 | struct rb_node *rbnext = rb_next(&crq->rb_node); | |
1875 | ||
1876 | if (rbnext) | |
1877 | return rb_entry_crq(rbnext)->request; | |
1878 | ||
1879 | return NULL; | |
1880 | } | |
1881 | ||
22e2c507 JA |
1882 | /* |
1883 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1884 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1885 | */ | |
1886 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1887 | { |
22e2c507 JA |
1888 | const int ioprio_class = cfqq->ioprio_class; |
1889 | const int ioprio = cfqq->ioprio; | |
1da177e4 | 1890 | |
22e2c507 JA |
1891 | if (has_fs_excl()) { |
1892 | /* | |
1893 | * boost idle prio on transactions that would lock out other | |
1894 | * users of the filesystem | |
1895 | */ | |
1896 | if (cfq_class_idle(cfqq)) | |
1897 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1898 | if (cfqq->ioprio > IOPRIO_NORM) | |
1899 | cfqq->ioprio = IOPRIO_NORM; | |
1900 | } else { | |
1901 | /* | |
1902 | * check if we need to unboost the queue | |
1903 | */ | |
1904 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1905 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1906 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1907 | cfqq->ioprio = cfqq->org_ioprio; | |
1908 | } | |
1da177e4 | 1909 | |
22e2c507 JA |
1910 | /* |
1911 | * refile between round-robin lists if we moved the priority class | |
1912 | */ | |
1913 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
3b18152c | 1914 | cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1915 | cfq_resort_rr_list(cfqq, 0); |
1916 | } | |
1da177e4 | 1917 | |
22e2c507 JA |
1918 | static inline int |
1919 | __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1920 | struct task_struct *task, int rw) | |
1921 | { | |
3b18152c JA |
1922 | #if 1 |
1923 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && | |
99f95e52 | 1924 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1925 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1926 | return ELV_MQUEUE_MUST; |
3b18152c | 1927 | } |
1da177e4 | 1928 | |
22e2c507 | 1929 | return ELV_MQUEUE_MAY; |
3b18152c | 1930 | #else |
22e2c507 JA |
1931 | if (!cfqq || task->flags & PF_MEMALLOC) |
1932 | return ELV_MQUEUE_MAY; | |
3b18152c JA |
1933 | if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { |
1934 | if (cfq_cfqq_wait_request(cfqq)) | |
22e2c507 | 1935 | return ELV_MQUEUE_MUST; |
1da177e4 | 1936 | |
22e2c507 JA |
1937 | /* |
1938 | * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we | |
1939 | * can quickly flood the queue with writes from a single task | |
1940 | */ | |
99f95e52 | 1941 | if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1942 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1943 | return ELV_MQUEUE_MUST; |
1da177e4 | 1944 | } |
22e2c507 JA |
1945 | |
1946 | return ELV_MQUEUE_MAY; | |
1da177e4 | 1947 | } |
22e2c507 JA |
1948 | if (cfq_class_idle(cfqq)) |
1949 | return ELV_MQUEUE_NO; | |
1950 | if (cfqq->allocated[rw] >= cfqd->max_queued) { | |
1951 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
1952 | int ret = ELV_MQUEUE_NO; | |
1da177e4 | 1953 | |
22e2c507 JA |
1954 | if (ioc && ioc->nr_batch_requests) |
1955 | ret = ELV_MQUEUE_MAY; | |
1956 | ||
1957 | put_io_context(ioc); | |
1958 | return ret; | |
1959 | } | |
1960 | ||
1961 | return ELV_MQUEUE_MAY; | |
1962 | #endif | |
1963 | } | |
1964 | ||
1965 | static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) | |
1966 | { | |
1967 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1968 | struct task_struct *tsk = current; | |
1969 | struct cfq_queue *cfqq; | |
1970 | ||
1971 | /* | |
1972 | * don't force setup of a queue from here, as a call to may_queue | |
1973 | * does not necessarily imply that a request actually will be queued. | |
1974 | * so just lookup a possibly existing queue, or return 'may queue' | |
1975 | * if that fails | |
1976 | */ | |
3b18152c | 1977 | cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); |
22e2c507 JA |
1978 | if (cfqq) { |
1979 | cfq_init_prio_data(cfqq); | |
1980 | cfq_prio_boost(cfqq); | |
1981 | ||
1982 | return __cfq_may_queue(cfqd, cfqq, tsk, rw); | |
1983 | } | |
1984 | ||
1985 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1986 | } |
1987 | ||
1988 | static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) | |
1989 | { | |
22e2c507 | 1990 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 | 1991 | struct request_list *rl = &q->rq; |
1da177e4 | 1992 | |
22e2c507 JA |
1993 | if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { |
1994 | smp_mb(); | |
1995 | if (waitqueue_active(&rl->wait[READ])) | |
1996 | wake_up(&rl->wait[READ]); | |
1997 | } | |
1998 | ||
1999 | if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { | |
2000 | smp_mb(); | |
2001 | if (waitqueue_active(&rl->wait[WRITE])) | |
2002 | wake_up(&rl->wait[WRITE]); | |
2003 | } | |
1da177e4 LT |
2004 | } |
2005 | ||
2006 | /* | |
2007 | * queue lock held here | |
2008 | */ | |
2009 | static void cfq_put_request(request_queue_t *q, struct request *rq) | |
2010 | { | |
2011 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2012 | struct cfq_rq *crq = RQ_DATA(rq); | |
2013 | ||
2014 | if (crq) { | |
2015 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 | 2016 | const int rw = rq_data_dir(rq); |
1da177e4 | 2017 | |
22e2c507 JA |
2018 | BUG_ON(!cfqq->allocated[rw]); |
2019 | cfqq->allocated[rw]--; | |
1da177e4 | 2020 | |
22e2c507 | 2021 | put_io_context(crq->io_context->ioc); |
1da177e4 LT |
2022 | |
2023 | mempool_free(crq, cfqd->crq_pool); | |
2024 | rq->elevator_private = NULL; | |
2025 | ||
1da177e4 LT |
2026 | cfq_check_waiters(q, cfqq); |
2027 | cfq_put_queue(cfqq); | |
2028 | } | |
2029 | } | |
2030 | ||
2031 | /* | |
22e2c507 | 2032 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2033 | */ |
22e2c507 JA |
2034 | static int |
2035 | cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, | |
8267e268 | 2036 | gfp_t gfp_mask) |
1da177e4 LT |
2037 | { |
2038 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 2039 | struct task_struct *tsk = current; |
1da177e4 LT |
2040 | struct cfq_io_context *cic; |
2041 | const int rw = rq_data_dir(rq); | |
3b18152c | 2042 | pid_t key = cfq_queue_pid(tsk, rw); |
22e2c507 | 2043 | struct cfq_queue *cfqq; |
1da177e4 LT |
2044 | struct cfq_rq *crq; |
2045 | unsigned long flags; | |
12a05732 | 2046 | int is_sync = key != CFQ_KEY_ASYNC; |
1da177e4 LT |
2047 | |
2048 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2049 | ||
e2d74ac0 | 2050 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2051 | |
1da177e4 LT |
2052 | spin_lock_irqsave(q->queue_lock, flags); |
2053 | ||
22e2c507 JA |
2054 | if (!cic) |
2055 | goto queue_fail; | |
2056 | ||
12a05732 | 2057 | if (!cic->cfqq[is_sync]) { |
6f325a13 | 2058 | cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask); |
22e2c507 JA |
2059 | if (!cfqq) |
2060 | goto queue_fail; | |
1da177e4 | 2061 | |
12a05732 | 2062 | cic->cfqq[is_sync] = cfqq; |
22e2c507 | 2063 | } else |
12a05732 | 2064 | cfqq = cic->cfqq[is_sync]; |
1da177e4 LT |
2065 | |
2066 | cfqq->allocated[rw]++; | |
3b18152c | 2067 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 JA |
2068 | cfqd->rq_starved = 0; |
2069 | atomic_inc(&cfqq->ref); | |
1da177e4 LT |
2070 | spin_unlock_irqrestore(q->queue_lock, flags); |
2071 | ||
1da177e4 LT |
2072 | crq = mempool_alloc(cfqd->crq_pool, gfp_mask); |
2073 | if (crq) { | |
2074 | RB_CLEAR(&crq->rb_node); | |
2075 | crq->rb_key = 0; | |
2076 | crq->request = rq; | |
2077 | INIT_HLIST_NODE(&crq->hash); | |
2078 | crq->cfq_queue = cfqq; | |
2079 | crq->io_context = cic; | |
3b18152c | 2080 | |
12a05732 | 2081 | if (is_sync) |
3b18152c JA |
2082 | cfq_mark_crq_is_sync(crq); |
2083 | else | |
2084 | cfq_clear_crq_is_sync(crq); | |
2085 | ||
1da177e4 | 2086 | rq->elevator_private = crq; |
1da177e4 LT |
2087 | return 0; |
2088 | } | |
2089 | ||
1da177e4 LT |
2090 | spin_lock_irqsave(q->queue_lock, flags); |
2091 | cfqq->allocated[rw]--; | |
22e2c507 | 2092 | if (!(cfqq->allocated[0] + cfqq->allocated[1])) |
3b18152c | 2093 | cfq_mark_cfqq_must_alloc(cfqq); |
1da177e4 | 2094 | cfq_put_queue(cfqq); |
22e2c507 JA |
2095 | queue_fail: |
2096 | if (cic) | |
2097 | put_io_context(cic->ioc); | |
2098 | /* | |
2099 | * mark us rq allocation starved. we need to kickstart the process | |
2100 | * ourselves if there are no pending requests that can do it for us. | |
2101 | * that would be an extremely rare OOM situation | |
2102 | */ | |
2103 | cfqd->rq_starved = 1; | |
3b18152c | 2104 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2105 | spin_unlock_irqrestore(q->queue_lock, flags); |
2106 | return 1; | |
2107 | } | |
2108 | ||
22e2c507 JA |
2109 | static void cfq_kick_queue(void *data) |
2110 | { | |
2111 | request_queue_t *q = data; | |
2112 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2113 | unsigned long flags; | |
2114 | ||
2115 | spin_lock_irqsave(q->queue_lock, flags); | |
2116 | ||
2117 | if (cfqd->rq_starved) { | |
2118 | struct request_list *rl = &q->rq; | |
2119 | ||
2120 | /* | |
2121 | * we aren't guaranteed to get a request after this, but we | |
2122 | * have to be opportunistic | |
2123 | */ | |
2124 | smp_mb(); | |
2125 | if (waitqueue_active(&rl->wait[READ])) | |
2126 | wake_up(&rl->wait[READ]); | |
2127 | if (waitqueue_active(&rl->wait[WRITE])) | |
2128 | wake_up(&rl->wait[WRITE]); | |
2129 | } | |
2130 | ||
2131 | blk_remove_plug(q); | |
2132 | q->request_fn(q); | |
2133 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2134 | } | |
2135 | ||
2136 | /* | |
2137 | * Timer running if the active_queue is currently idling inside its time slice | |
2138 | */ | |
2139 | static void cfq_idle_slice_timer(unsigned long data) | |
2140 | { | |
2141 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2142 | struct cfq_queue *cfqq; | |
2143 | unsigned long flags; | |
2144 | ||
2145 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2146 | ||
2147 | if ((cfqq = cfqd->active_queue) != NULL) { | |
2148 | unsigned long now = jiffies; | |
2149 | ||
2150 | /* | |
2151 | * expired | |
2152 | */ | |
2153 | if (time_after(now, cfqq->slice_end)) | |
2154 | goto expire; | |
2155 | ||
2156 | /* | |
2157 | * only expire and reinvoke request handler, if there are | |
2158 | * other queues with pending requests | |
2159 | */ | |
b4878f24 | 2160 | if (!cfqd->busy_queues) { |
22e2c507 JA |
2161 | cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); |
2162 | add_timer(&cfqd->idle_slice_timer); | |
2163 | goto out_cont; | |
2164 | } | |
2165 | ||
2166 | /* | |
2167 | * not expired and it has a request pending, let it dispatch | |
2168 | */ | |
2169 | if (!RB_EMPTY(&cfqq->sort_list)) { | |
3b18152c | 2170 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2171 | goto out_kick; |
2172 | } | |
2173 | } | |
2174 | expire: | |
2175 | cfq_slice_expired(cfqd, 0); | |
2176 | out_kick: | |
3b18152c | 2177 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2178 | out_cont: |
2179 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2180 | } | |
2181 | ||
2182 | /* | |
2183 | * Timer running if an idle class queue is waiting for service | |
2184 | */ | |
2185 | static void cfq_idle_class_timer(unsigned long data) | |
2186 | { | |
2187 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2188 | unsigned long flags, end; | |
2189 | ||
2190 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2191 | ||
2192 | /* | |
2193 | * race with a non-idle queue, reset timer | |
2194 | */ | |
2195 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
2196 | if (!time_after_eq(jiffies, end)) { | |
2197 | cfqd->idle_class_timer.expires = end; | |
2198 | add_timer(&cfqd->idle_class_timer); | |
2199 | } else | |
3b18152c | 2200 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2201 | |
2202 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2203 | } | |
2204 | ||
3b18152c JA |
2205 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2206 | { | |
2207 | del_timer_sync(&cfqd->idle_slice_timer); | |
2208 | del_timer_sync(&cfqd->idle_class_timer); | |
2209 | blk_sync_queue(cfqd->queue); | |
2210 | } | |
22e2c507 | 2211 | |
1da177e4 LT |
2212 | static void cfq_exit_queue(elevator_t *e) |
2213 | { | |
22e2c507 | 2214 | struct cfq_data *cfqd = e->elevator_data; |
d9ff4187 | 2215 | request_queue_t *q = cfqd->queue; |
22e2c507 | 2216 | |
3b18152c | 2217 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2218 | |
3793c65c | 2219 | spin_lock(&cfq_exit_lock); |
d9ff4187 | 2220 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2221 | |
d9ff4187 AV |
2222 | if (cfqd->active_queue) |
2223 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); | |
e2d74ac0 JA |
2224 | |
2225 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2226 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2227 | struct cfq_io_context, | |
2228 | queue_list); | |
2229 | if (cic->cfqq[ASYNC]) { | |
2230 | cfq_put_queue(cic->cfqq[ASYNC]); | |
2231 | cic->cfqq[ASYNC] = NULL; | |
2232 | } | |
2233 | if (cic->cfqq[SYNC]) { | |
2234 | cfq_put_queue(cic->cfqq[SYNC]); | |
2235 | cic->cfqq[SYNC] = NULL; | |
2236 | } | |
2237 | cic->key = NULL; | |
2238 | list_del_init(&cic->queue_list); | |
2239 | } | |
e2d74ac0 | 2240 | |
d9ff4187 | 2241 | spin_unlock_irq(q->queue_lock); |
3793c65c | 2242 | spin_unlock(&cfq_exit_lock); |
a90d742e AV |
2243 | |
2244 | cfq_shutdown_timer_wq(cfqd); | |
2245 | ||
2246 | mempool_destroy(cfqd->crq_pool); | |
2247 | kfree(cfqd->crq_hash); | |
2248 | kfree(cfqd->cfq_hash); | |
2249 | kfree(cfqd); | |
1da177e4 LT |
2250 | } |
2251 | ||
2252 | static int cfq_init_queue(request_queue_t *q, elevator_t *e) | |
2253 | { | |
2254 | struct cfq_data *cfqd; | |
2255 | int i; | |
2256 | ||
2257 | cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); | |
2258 | if (!cfqd) | |
2259 | return -ENOMEM; | |
2260 | ||
2261 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 JA |
2262 | |
2263 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2264 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2265 | ||
2266 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2267 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2268 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
1da177e4 | 2269 | INIT_LIST_HEAD(&cfqd->empty_list); |
d9ff4187 | 2270 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 LT |
2271 | |
2272 | cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); | |
2273 | if (!cfqd->crq_hash) | |
2274 | goto out_crqhash; | |
2275 | ||
2276 | cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); | |
2277 | if (!cfqd->cfq_hash) | |
2278 | goto out_cfqhash; | |
2279 | ||
93d2341c | 2280 | cfqd->crq_pool = mempool_create_slab_pool(BLKDEV_MIN_RQ, crq_pool); |
1da177e4 LT |
2281 | if (!cfqd->crq_pool) |
2282 | goto out_crqpool; | |
2283 | ||
2284 | for (i = 0; i < CFQ_MHASH_ENTRIES; i++) | |
2285 | INIT_HLIST_HEAD(&cfqd->crq_hash[i]); | |
2286 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2287 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2288 | ||
2289 | e->elevator_data = cfqd; | |
2290 | ||
2291 | cfqd->queue = q; | |
1da177e4 | 2292 | |
22e2c507 | 2293 | cfqd->max_queued = q->nr_requests / 4; |
1da177e4 | 2294 | q->nr_batching = cfq_queued; |
22e2c507 JA |
2295 | |
2296 | init_timer(&cfqd->idle_slice_timer); | |
2297 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2298 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2299 | ||
2300 | init_timer(&cfqd->idle_class_timer); | |
2301 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2302 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2303 | ||
2304 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); | |
2305 | ||
1da177e4 LT |
2306 | cfqd->cfq_queued = cfq_queued; |
2307 | cfqd->cfq_quantum = cfq_quantum; | |
22e2c507 JA |
2308 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2309 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2310 | cfqd->cfq_back_max = cfq_back_max; |
2311 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2312 | cfqd->cfq_slice[0] = cfq_slice_async; |
2313 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2314 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2315 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2316 | |
1da177e4 LT |
2317 | return 0; |
2318 | out_crqpool: | |
2319 | kfree(cfqd->cfq_hash); | |
2320 | out_cfqhash: | |
2321 | kfree(cfqd->crq_hash); | |
2322 | out_crqhash: | |
2323 | kfree(cfqd); | |
2324 | return -ENOMEM; | |
2325 | } | |
2326 | ||
2327 | static void cfq_slab_kill(void) | |
2328 | { | |
2329 | if (crq_pool) | |
2330 | kmem_cache_destroy(crq_pool); | |
2331 | if (cfq_pool) | |
2332 | kmem_cache_destroy(cfq_pool); | |
2333 | if (cfq_ioc_pool) | |
2334 | kmem_cache_destroy(cfq_ioc_pool); | |
2335 | } | |
2336 | ||
2337 | static int __init cfq_slab_setup(void) | |
2338 | { | |
2339 | crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, | |
2340 | NULL, NULL); | |
2341 | if (!crq_pool) | |
2342 | goto fail; | |
2343 | ||
2344 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2345 | NULL, NULL); | |
2346 | if (!cfq_pool) | |
2347 | goto fail; | |
2348 | ||
2349 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2350 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2351 | if (!cfq_ioc_pool) | |
2352 | goto fail; | |
2353 | ||
2354 | return 0; | |
2355 | fail: | |
2356 | cfq_slab_kill(); | |
2357 | return -ENOMEM; | |
2358 | } | |
2359 | ||
1da177e4 LT |
2360 | /* |
2361 | * sysfs parts below --> | |
2362 | */ | |
1da177e4 LT |
2363 | |
2364 | static ssize_t | |
2365 | cfq_var_show(unsigned int var, char *page) | |
2366 | { | |
2367 | return sprintf(page, "%d\n", var); | |
2368 | } | |
2369 | ||
2370 | static ssize_t | |
2371 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2372 | { | |
2373 | char *p = (char *) page; | |
2374 | ||
2375 | *var = simple_strtoul(p, &p, 10); | |
2376 | return count; | |
2377 | } | |
2378 | ||
1da177e4 | 2379 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2380 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2381 | { \ |
3d1ab40f | 2382 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2383 | unsigned int __data = __VAR; \ |
2384 | if (__CONV) \ | |
2385 | __data = jiffies_to_msecs(__data); \ | |
2386 | return cfq_var_show(__data, (page)); \ | |
2387 | } | |
2388 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2389 | SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); | |
22e2c507 JA |
2390 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2391 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2392 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2393 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2394 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2395 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2396 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2397 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2398 | #undef SHOW_FUNCTION |
2399 | ||
2400 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2401 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2402 | { \ |
3d1ab40f | 2403 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2404 | unsigned int __data; \ |
2405 | int ret = cfq_var_store(&__data, (page), count); \ | |
2406 | if (__data < (MIN)) \ | |
2407 | __data = (MIN); \ | |
2408 | else if (__data > (MAX)) \ | |
2409 | __data = (MAX); \ | |
2410 | if (__CONV) \ | |
2411 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2412 | else \ | |
2413 | *(__PTR) = __data; \ | |
2414 | return ret; \ | |
2415 | } | |
2416 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2417 | STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); | |
22e2c507 JA |
2418 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2419 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2420 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2421 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2422 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2423 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2424 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2425 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2426 | #undef STORE_FUNCTION |
2427 | ||
e572ec7e AV |
2428 | #define CFQ_ATTR(name) \ |
2429 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2430 | ||
2431 | static struct elv_fs_entry cfq_attrs[] = { | |
2432 | CFQ_ATTR(quantum), | |
2433 | CFQ_ATTR(queued), | |
2434 | CFQ_ATTR(fifo_expire_sync), | |
2435 | CFQ_ATTR(fifo_expire_async), | |
2436 | CFQ_ATTR(back_seek_max), | |
2437 | CFQ_ATTR(back_seek_penalty), | |
2438 | CFQ_ATTR(slice_sync), | |
2439 | CFQ_ATTR(slice_async), | |
2440 | CFQ_ATTR(slice_async_rq), | |
2441 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2442 | __ATTR_NULL |
1da177e4 LT |
2443 | }; |
2444 | ||
1da177e4 LT |
2445 | static struct elevator_type iosched_cfq = { |
2446 | .ops = { | |
2447 | .elevator_merge_fn = cfq_merge, | |
2448 | .elevator_merged_fn = cfq_merged_request, | |
2449 | .elevator_merge_req_fn = cfq_merged_requests, | |
b4878f24 | 2450 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2451 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2452 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2453 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2454 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2455 | .elevator_completed_req_fn = cfq_completed_request, | |
2456 | .elevator_former_req_fn = cfq_former_request, | |
2457 | .elevator_latter_req_fn = cfq_latter_request, | |
2458 | .elevator_set_req_fn = cfq_set_request, | |
2459 | .elevator_put_req_fn = cfq_put_request, | |
2460 | .elevator_may_queue_fn = cfq_may_queue, | |
2461 | .elevator_init_fn = cfq_init_queue, | |
2462 | .elevator_exit_fn = cfq_exit_queue, | |
e17a9489 | 2463 | .trim = cfq_trim, |
1da177e4 | 2464 | }, |
3d1ab40f | 2465 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2466 | .elevator_name = "cfq", |
2467 | .elevator_owner = THIS_MODULE, | |
2468 | }; | |
2469 | ||
2470 | static int __init cfq_init(void) | |
2471 | { | |
2472 | int ret; | |
2473 | ||
22e2c507 JA |
2474 | /* |
2475 | * could be 0 on HZ < 1000 setups | |
2476 | */ | |
2477 | if (!cfq_slice_async) | |
2478 | cfq_slice_async = 1; | |
2479 | if (!cfq_slice_idle) | |
2480 | cfq_slice_idle = 1; | |
2481 | ||
1da177e4 LT |
2482 | if (cfq_slab_setup()) |
2483 | return -ENOMEM; | |
2484 | ||
2485 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2486 | if (ret) |
2487 | cfq_slab_kill(); | |
1da177e4 | 2488 | |
1da177e4 LT |
2489 | return ret; |
2490 | } | |
2491 | ||
2492 | static void __exit cfq_exit(void) | |
2493 | { | |
334e94de | 2494 | DECLARE_COMPLETION(all_gone); |
1da177e4 | 2495 | elv_unregister(&iosched_cfq); |
334e94de | 2496 | ioc_gone = &all_gone; |
fba82272 OH |
2497 | /* ioc_gone's update must be visible before reading ioc_count */ |
2498 | smp_wmb(); | |
334e94de | 2499 | if (atomic_read(&ioc_count)) |
fba82272 | 2500 | wait_for_completion(ioc_gone); |
334e94de | 2501 | synchronize_rcu(); |
83521d3e | 2502 | cfq_slab_kill(); |
1da177e4 LT |
2503 | } |
2504 | ||
2505 | module_init(cfq_init); | |
2506 | module_exit(cfq_exit); | |
2507 | ||
2508 | MODULE_AUTHOR("Jens Axboe"); | |
2509 | MODULE_LICENSE("GPL"); | |
2510 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |