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 | */ | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/fs.h> | |
11 | #include <linux/blkdev.h> | |
12 | #include <linux/elevator.h> | |
13 | #include <linux/bio.h> | |
14 | #include <linux/config.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/compiler.h> | |
19 | #include <linux/hash.h> | |
20 | #include <linux/rbtree.h> | |
21 | #include <linux/mempool.h> | |
22e2c507 JA |
22 | #include <linux/ioprio.h> |
23 | #include <linux/writeback.h> | |
1da177e4 LT |
24 | |
25 | /* | |
26 | * tunables | |
27 | */ | |
64100099 AV |
28 | static const int cfq_quantum = 4; /* max queue in one round of service */ |
29 | static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ | |
30 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; | |
31 | static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ | |
32 | static const int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
1da177e4 | 33 | |
64100099 | 34 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 35 | static int cfq_slice_async = HZ / 25; |
64100099 | 36 | static const int cfq_slice_async_rq = 2; |
3b18152c | 37 | static int cfq_slice_idle = HZ / 100; |
22e2c507 JA |
38 | |
39 | #define CFQ_IDLE_GRACE (HZ / 10) | |
40 | #define CFQ_SLICE_SCALE (5) | |
41 | ||
42 | #define CFQ_KEY_ASYNC (0) | |
3b18152c | 43 | #define CFQ_KEY_ANY (0xffff) |
22e2c507 JA |
44 | |
45 | /* | |
46 | * disable queueing at the driver/hardware level | |
47 | */ | |
64100099 | 48 | static const int cfq_max_depth = 2; |
22e2c507 | 49 | |
a6a0763a AV |
50 | static DEFINE_RWLOCK(cfq_exit_lock); |
51 | ||
1da177e4 LT |
52 | /* |
53 | * for the hash of cfqq inside the cfqd | |
54 | */ | |
55 | #define CFQ_QHASH_SHIFT 6 | |
56 | #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) | |
57 | #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) | |
58 | ||
59 | /* | |
60 | * for the hash of crq inside the cfqq | |
61 | */ | |
62 | #define CFQ_MHASH_SHIFT 6 | |
63 | #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) | |
64 | #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) | |
65 | #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) | |
66 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
67 | #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) | |
68 | ||
69 | #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) | |
22e2c507 | 70 | #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) |
1da177e4 LT |
71 | |
72 | #define RQ_DATA(rq) (rq)->elevator_private | |
73 | ||
74 | /* | |
75 | * rb-tree defines | |
76 | */ | |
77 | #define RB_NONE (2) | |
78 | #define RB_EMPTY(node) ((node)->rb_node == NULL) | |
79 | #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE | |
80 | #define RB_CLEAR(node) do { \ | |
81 | (node)->rb_parent = NULL; \ | |
82 | RB_CLEAR_COLOR((node)); \ | |
83 | (node)->rb_right = NULL; \ | |
84 | (node)->rb_left = NULL; \ | |
85 | } while (0) | |
86 | #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) | |
1da177e4 LT |
87 | #define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) |
88 | #define rq_rb_key(rq) (rq)->sector | |
89 | ||
1da177e4 LT |
90 | static kmem_cache_t *crq_pool; |
91 | static kmem_cache_t *cfq_pool; | |
92 | static kmem_cache_t *cfq_ioc_pool; | |
93 | ||
22e2c507 JA |
94 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
95 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
96 | #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) | |
97 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
98 | ||
3b18152c JA |
99 | #define ASYNC (0) |
100 | #define SYNC (1) | |
101 | ||
102 | #define cfq_cfqq_dispatched(cfqq) \ | |
103 | ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) | |
104 | ||
105 | #define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) | |
106 | ||
107 | #define cfq_cfqq_sync(cfqq) \ | |
108 | (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) | |
22e2c507 JA |
109 | |
110 | /* | |
111 | * Per block device queue structure | |
112 | */ | |
1da177e4 | 113 | struct cfq_data { |
22e2c507 JA |
114 | atomic_t ref; |
115 | request_queue_t *queue; | |
116 | ||
117 | /* | |
118 | * rr list of queues with requests and the count of them | |
119 | */ | |
120 | struct list_head rr_list[CFQ_PRIO_LISTS]; | |
121 | struct list_head busy_rr; | |
122 | struct list_head cur_rr; | |
123 | struct list_head idle_rr; | |
124 | unsigned int busy_queues; | |
125 | ||
126 | /* | |
127 | * non-ordered list of empty cfqq's | |
128 | */ | |
1da177e4 LT |
129 | struct list_head empty_list; |
130 | ||
22e2c507 JA |
131 | /* |
132 | * cfqq lookup hash | |
133 | */ | |
1da177e4 | 134 | struct hlist_head *cfq_hash; |
1da177e4 | 135 | |
22e2c507 JA |
136 | /* |
137 | * global crq hash for all queues | |
138 | */ | |
139 | struct hlist_head *crq_hash; | |
1da177e4 LT |
140 | |
141 | unsigned int max_queued; | |
142 | ||
22e2c507 | 143 | mempool_t *crq_pool; |
1da177e4 | 144 | |
22e2c507 | 145 | int rq_in_driver; |
1da177e4 | 146 | |
22e2c507 JA |
147 | /* |
148 | * schedule slice state info | |
149 | */ | |
150 | /* | |
151 | * idle window management | |
152 | */ | |
153 | struct timer_list idle_slice_timer; | |
154 | struct work_struct unplug_work; | |
1da177e4 | 155 | |
22e2c507 JA |
156 | struct cfq_queue *active_queue; |
157 | struct cfq_io_context *active_cic; | |
158 | int cur_prio, cur_end_prio; | |
159 | unsigned int dispatch_slice; | |
160 | ||
161 | struct timer_list idle_class_timer; | |
1da177e4 LT |
162 | |
163 | sector_t last_sector; | |
22e2c507 | 164 | unsigned long last_end_request; |
1da177e4 | 165 | |
22e2c507 | 166 | unsigned int rq_starved; |
1da177e4 LT |
167 | |
168 | /* | |
169 | * tunables, see top of file | |
170 | */ | |
171 | unsigned int cfq_quantum; | |
172 | unsigned int cfq_queued; | |
22e2c507 | 173 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
174 | unsigned int cfq_back_penalty; |
175 | unsigned int cfq_back_max; | |
22e2c507 JA |
176 | unsigned int cfq_slice[2]; |
177 | unsigned int cfq_slice_async_rq; | |
178 | unsigned int cfq_slice_idle; | |
179 | unsigned int cfq_max_depth; | |
1da177e4 LT |
180 | }; |
181 | ||
22e2c507 JA |
182 | /* |
183 | * Per process-grouping structure | |
184 | */ | |
1da177e4 LT |
185 | struct cfq_queue { |
186 | /* reference count */ | |
187 | atomic_t ref; | |
188 | /* parent cfq_data */ | |
189 | struct cfq_data *cfqd; | |
22e2c507 | 190 | /* cfqq lookup hash */ |
1da177e4 LT |
191 | struct hlist_node cfq_hash; |
192 | /* hash key */ | |
22e2c507 | 193 | unsigned int key; |
1da177e4 LT |
194 | /* on either rr or empty list of cfqd */ |
195 | struct list_head cfq_list; | |
196 | /* sorted list of pending requests */ | |
197 | struct rb_root sort_list; | |
198 | /* if fifo isn't expired, next request to serve */ | |
199 | struct cfq_rq *next_crq; | |
200 | /* requests queued in sort_list */ | |
201 | int queued[2]; | |
202 | /* currently allocated requests */ | |
203 | int allocated[2]; | |
204 | /* fifo list of requests in sort_list */ | |
22e2c507 | 205 | struct list_head fifo; |
1da177e4 | 206 | |
22e2c507 JA |
207 | unsigned long slice_start; |
208 | unsigned long slice_end; | |
209 | unsigned long slice_left; | |
210 | unsigned long service_last; | |
1da177e4 | 211 | |
3b18152c JA |
212 | /* number of requests that are on the dispatch list */ |
213 | int on_dispatch[2]; | |
22e2c507 JA |
214 | |
215 | /* io prio of this group */ | |
216 | unsigned short ioprio, org_ioprio; | |
217 | unsigned short ioprio_class, org_ioprio_class; | |
218 | ||
3b18152c JA |
219 | /* various state flags, see below */ |
220 | unsigned int flags; | |
1da177e4 LT |
221 | }; |
222 | ||
223 | struct cfq_rq { | |
224 | struct rb_node rb_node; | |
225 | sector_t rb_key; | |
226 | struct request *request; | |
227 | struct hlist_node hash; | |
228 | ||
229 | struct cfq_queue *cfq_queue; | |
230 | struct cfq_io_context *io_context; | |
231 | ||
3b18152c | 232 | unsigned int crq_flags; |
1da177e4 LT |
233 | }; |
234 | ||
3b18152c JA |
235 | enum cfqq_state_flags { |
236 | CFQ_CFQQ_FLAG_on_rr = 0, | |
237 | CFQ_CFQQ_FLAG_wait_request, | |
238 | CFQ_CFQQ_FLAG_must_alloc, | |
239 | CFQ_CFQQ_FLAG_must_alloc_slice, | |
240 | CFQ_CFQQ_FLAG_must_dispatch, | |
241 | CFQ_CFQQ_FLAG_fifo_expire, | |
242 | CFQ_CFQQ_FLAG_idle_window, | |
243 | CFQ_CFQQ_FLAG_prio_changed, | |
3b18152c JA |
244 | }; |
245 | ||
246 | #define CFQ_CFQQ_FNS(name) \ | |
247 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
248 | { \ | |
249 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
250 | } \ | |
251 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
252 | { \ | |
253 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
254 | } \ | |
255 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
256 | { \ | |
257 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
258 | } | |
259 | ||
260 | CFQ_CFQQ_FNS(on_rr); | |
261 | CFQ_CFQQ_FNS(wait_request); | |
262 | CFQ_CFQQ_FNS(must_alloc); | |
263 | CFQ_CFQQ_FNS(must_alloc_slice); | |
264 | CFQ_CFQQ_FNS(must_dispatch); | |
265 | CFQ_CFQQ_FNS(fifo_expire); | |
266 | CFQ_CFQQ_FNS(idle_window); | |
267 | CFQ_CFQQ_FNS(prio_changed); | |
3b18152c JA |
268 | #undef CFQ_CFQQ_FNS |
269 | ||
270 | enum cfq_rq_state_flags { | |
b4878f24 | 271 | CFQ_CRQ_FLAG_is_sync = 0, |
3b18152c JA |
272 | }; |
273 | ||
274 | #define CFQ_CRQ_FNS(name) \ | |
275 | static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ | |
276 | { \ | |
277 | crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ | |
278 | } \ | |
279 | static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ | |
280 | { \ | |
281 | crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ | |
282 | } \ | |
283 | static inline int cfq_crq_##name(const struct cfq_rq *crq) \ | |
284 | { \ | |
285 | return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ | |
286 | } | |
287 | ||
3b18152c | 288 | CFQ_CRQ_FNS(is_sync); |
3b18152c JA |
289 | #undef CFQ_CRQ_FNS |
290 | ||
291 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); | |
b4878f24 | 292 | static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); |
1da177e4 LT |
293 | static void cfq_put_cfqd(struct cfq_data *cfqd); |
294 | ||
22e2c507 | 295 | #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) |
1da177e4 LT |
296 | |
297 | /* | |
298 | * lots of deadline iosched dupes, can be abstracted later... | |
299 | */ | |
300 | static inline void cfq_del_crq_hash(struct cfq_rq *crq) | |
301 | { | |
302 | hlist_del_init(&crq->hash); | |
303 | } | |
304 | ||
1da177e4 LT |
305 | static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) |
306 | { | |
307 | const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); | |
308 | ||
1da177e4 LT |
309 | hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); |
310 | } | |
311 | ||
312 | static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) | |
313 | { | |
314 | struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; | |
315 | struct hlist_node *entry, *next; | |
316 | ||
317 | hlist_for_each_safe(entry, next, hash_list) { | |
318 | struct cfq_rq *crq = list_entry_hash(entry); | |
319 | struct request *__rq = crq->request; | |
320 | ||
1da177e4 LT |
321 | if (!rq_mergeable(__rq)) { |
322 | cfq_del_crq_hash(crq); | |
323 | continue; | |
324 | } | |
325 | ||
326 | if (rq_hash_key(__rq) == offset) | |
327 | return __rq; | |
328 | } | |
329 | ||
330 | return NULL; | |
331 | } | |
332 | ||
99f95e52 AM |
333 | /* |
334 | * scheduler run of queue, if there are requests pending and no one in the | |
335 | * driver that will restart queueing | |
336 | */ | |
337 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
338 | { | |
7b14e3b5 | 339 | if (cfqd->busy_queues) |
99f95e52 AM |
340 | kblockd_schedule_work(&cfqd->unplug_work); |
341 | } | |
342 | ||
343 | static int cfq_queue_empty(request_queue_t *q) | |
344 | { | |
345 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
346 | ||
b4878f24 | 347 | return !cfqd->busy_queues; |
99f95e52 AM |
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 | |
353 | * behind the head are penalized and only allowed to a certain extent. | |
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; | |
359 | int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */ | |
360 | unsigned long back_max; | |
361 | ||
362 | if (crq1 == NULL || crq1 == crq2) | |
363 | return crq2; | |
364 | if (crq2 == NULL) | |
365 | return crq1; | |
9c2c38a1 | 366 | |
9c2c38a1 JA |
367 | if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) |
368 | return crq1; | |
369 | else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) | |
22e2c507 | 370 | return crq2; |
1da177e4 LT |
371 | |
372 | s1 = crq1->request->sector; | |
373 | s2 = crq2->request->sector; | |
374 | ||
375 | last = cfqd->last_sector; | |
376 | ||
1da177e4 LT |
377 | /* |
378 | * by definition, 1KiB is 2 sectors | |
379 | */ | |
380 | back_max = cfqd->cfq_back_max * 2; | |
381 | ||
382 | /* | |
383 | * Strict one way elevator _except_ in the case where we allow | |
384 | * short backward seeks which are biased as twice the cost of a | |
385 | * similar forward seek. | |
386 | */ | |
387 | if (s1 >= last) | |
388 | d1 = s1 - last; | |
389 | else if (s1 + back_max >= last) | |
390 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
391 | else | |
392 | r1_wrap = 1; | |
393 | ||
394 | if (s2 >= last) | |
395 | d2 = s2 - last; | |
396 | else if (s2 + back_max >= last) | |
397 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
398 | else | |
399 | r2_wrap = 1; | |
400 | ||
401 | /* Found required data */ | |
402 | if (!r1_wrap && r2_wrap) | |
403 | return crq1; | |
404 | else if (!r2_wrap && r1_wrap) | |
405 | return crq2; | |
406 | else if (r1_wrap && r2_wrap) { | |
407 | /* both behind the head */ | |
408 | if (s1 <= s2) | |
409 | return crq1; | |
410 | else | |
411 | return crq2; | |
412 | } | |
413 | ||
414 | /* Both requests in front of the head */ | |
415 | if (d1 < d2) | |
416 | return crq1; | |
417 | else if (d2 < d1) | |
418 | return crq2; | |
419 | else { | |
420 | if (s1 >= s2) | |
421 | return crq1; | |
422 | else | |
423 | return crq2; | |
424 | } | |
425 | } | |
426 | ||
427 | /* | |
428 | * would be nice to take fifo expire time into account as well | |
429 | */ | |
430 | static struct cfq_rq * | |
431 | cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
432 | struct cfq_rq *last) | |
433 | { | |
434 | struct cfq_rq *crq_next = NULL, *crq_prev = NULL; | |
435 | struct rb_node *rbnext, *rbprev; | |
436 | ||
b4878f24 | 437 | if (!(rbnext = rb_next(&last->rb_node))) { |
1da177e4 | 438 | rbnext = rb_first(&cfqq->sort_list); |
22e2c507 JA |
439 | if (rbnext == &last->rb_node) |
440 | rbnext = NULL; | |
441 | } | |
1da177e4 LT |
442 | |
443 | rbprev = rb_prev(&last->rb_node); | |
444 | ||
445 | if (rbprev) | |
446 | crq_prev = rb_entry_crq(rbprev); | |
447 | if (rbnext) | |
448 | crq_next = rb_entry_crq(rbnext); | |
449 | ||
450 | return cfq_choose_req(cfqd, crq_next, crq_prev); | |
451 | } | |
452 | ||
453 | static void cfq_update_next_crq(struct cfq_rq *crq) | |
454 | { | |
455 | struct cfq_queue *cfqq = crq->cfq_queue; | |
456 | ||
457 | if (cfqq->next_crq == crq) | |
458 | cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); | |
459 | } | |
460 | ||
22e2c507 | 461 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
1da177e4 | 462 | { |
22e2c507 JA |
463 | struct cfq_data *cfqd = cfqq->cfqd; |
464 | struct list_head *list, *entry; | |
1da177e4 | 465 | |
3b18152c | 466 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 467 | |
22e2c507 | 468 | list_del(&cfqq->cfq_list); |
1da177e4 | 469 | |
22e2c507 JA |
470 | if (cfq_class_rt(cfqq)) |
471 | list = &cfqd->cur_rr; | |
472 | else if (cfq_class_idle(cfqq)) | |
473 | list = &cfqd->idle_rr; | |
474 | else { | |
475 | /* | |
476 | * if cfqq has requests in flight, don't allow it to be | |
477 | * found in cfq_set_active_queue before it has finished them. | |
478 | * this is done to increase fairness between a process that | |
479 | * has lots of io pending vs one that only generates one | |
480 | * sporadically or synchronously | |
481 | */ | |
3b18152c | 482 | if (cfq_cfqq_dispatched(cfqq)) |
22e2c507 JA |
483 | list = &cfqd->busy_rr; |
484 | else | |
485 | list = &cfqd->rr_list[cfqq->ioprio]; | |
1da177e4 LT |
486 | } |
487 | ||
22e2c507 JA |
488 | /* |
489 | * if queue was preempted, just add to front to be fair. busy_rr | |
490 | * isn't sorted. | |
491 | */ | |
492 | if (preempted || list == &cfqd->busy_rr) { | |
493 | list_add(&cfqq->cfq_list, list); | |
1da177e4 | 494 | return; |
22e2c507 | 495 | } |
1da177e4 LT |
496 | |
497 | /* | |
22e2c507 | 498 | * sort by when queue was last serviced |
1da177e4 | 499 | */ |
22e2c507 JA |
500 | entry = list; |
501 | while ((entry = entry->prev) != list) { | |
1da177e4 LT |
502 | struct cfq_queue *__cfqq = list_entry_cfqq(entry); |
503 | ||
22e2c507 JA |
504 | if (!__cfqq->service_last) |
505 | break; | |
506 | if (time_before(__cfqq->service_last, cfqq->service_last)) | |
1da177e4 | 507 | break; |
1da177e4 LT |
508 | } |
509 | ||
510 | list_add(&cfqq->cfq_list, entry); | |
511 | } | |
512 | ||
513 | /* | |
514 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 515 | * the pending list according to last request service |
1da177e4 LT |
516 | */ |
517 | static inline void | |
b4878f24 | 518 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 519 | { |
3b18152c JA |
520 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
521 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
522 | cfqd->busy_queues++; |
523 | ||
b4878f24 | 524 | cfq_resort_rr_list(cfqq, 0); |
1da177e4 LT |
525 | } |
526 | ||
527 | static inline void | |
528 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
529 | { | |
3b18152c JA |
530 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
531 | cfq_clear_cfqq_on_rr(cfqq); | |
22e2c507 | 532 | list_move(&cfqq->cfq_list, &cfqd->empty_list); |
1da177e4 LT |
533 | |
534 | BUG_ON(!cfqd->busy_queues); | |
535 | cfqd->busy_queues--; | |
536 | } | |
537 | ||
538 | /* | |
539 | * rb tree support functions | |
540 | */ | |
541 | static inline void cfq_del_crq_rb(struct cfq_rq *crq) | |
542 | { | |
543 | struct cfq_queue *cfqq = crq->cfq_queue; | |
b4878f24 JA |
544 | struct cfq_data *cfqd = cfqq->cfqd; |
545 | const int sync = cfq_crq_is_sync(crq); | |
1da177e4 | 546 | |
b4878f24 JA |
547 | BUG_ON(!cfqq->queued[sync]); |
548 | cfqq->queued[sync]--; | |
1da177e4 | 549 | |
b4878f24 | 550 | cfq_update_next_crq(crq); |
1da177e4 | 551 | |
b4878f24 JA |
552 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
553 | RB_CLEAR_COLOR(&crq->rb_node); | |
1da177e4 | 554 | |
b4878f24 JA |
555 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list)) |
556 | cfq_del_cfqq_rr(cfqd, cfqq); | |
1da177e4 LT |
557 | } |
558 | ||
559 | static struct cfq_rq * | |
560 | __cfq_add_crq_rb(struct cfq_rq *crq) | |
561 | { | |
562 | struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; | |
563 | struct rb_node *parent = NULL; | |
564 | struct cfq_rq *__crq; | |
565 | ||
566 | while (*p) { | |
567 | parent = *p; | |
568 | __crq = rb_entry_crq(parent); | |
569 | ||
570 | if (crq->rb_key < __crq->rb_key) | |
571 | p = &(*p)->rb_left; | |
572 | else if (crq->rb_key > __crq->rb_key) | |
573 | p = &(*p)->rb_right; | |
574 | else | |
575 | return __crq; | |
576 | } | |
577 | ||
578 | rb_link_node(&crq->rb_node, parent, p); | |
579 | return NULL; | |
580 | } | |
581 | ||
582 | static void cfq_add_crq_rb(struct cfq_rq *crq) | |
583 | { | |
584 | struct cfq_queue *cfqq = crq->cfq_queue; | |
585 | struct cfq_data *cfqd = cfqq->cfqd; | |
586 | struct request *rq = crq->request; | |
587 | struct cfq_rq *__alias; | |
588 | ||
589 | crq->rb_key = rq_rb_key(rq); | |
3b18152c | 590 | cfqq->queued[cfq_crq_is_sync(crq)]++; |
1da177e4 LT |
591 | |
592 | /* | |
593 | * looks a little odd, but the first insert might return an alias. | |
594 | * if that happens, put the alias on the dispatch list | |
595 | */ | |
596 | while ((__alias = __cfq_add_crq_rb(crq)) != NULL) | |
b4878f24 | 597 | cfq_dispatch_insert(cfqd->queue, __alias); |
1da177e4 LT |
598 | |
599 | rb_insert_color(&crq->rb_node, &cfqq->sort_list); | |
600 | ||
3b18152c | 601 | if (!cfq_cfqq_on_rr(cfqq)) |
b4878f24 | 602 | cfq_add_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
603 | |
604 | /* | |
605 | * check if this request is a better next-serve candidate | |
606 | */ | |
607 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
608 | } | |
609 | ||
610 | static inline void | |
611 | cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
612 | { | |
b4878f24 JA |
613 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
614 | cfqq->queued[cfq_crq_is_sync(crq)]--; | |
1da177e4 LT |
615 | |
616 | cfq_add_crq_rb(crq); | |
617 | } | |
618 | ||
22e2c507 JA |
619 | static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector) |
620 | ||
1da177e4 | 621 | { |
3b18152c | 622 | struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY); |
1da177e4 LT |
623 | struct rb_node *n; |
624 | ||
625 | if (!cfqq) | |
626 | goto out; | |
627 | ||
628 | n = cfqq->sort_list.rb_node; | |
629 | while (n) { | |
630 | struct cfq_rq *crq = rb_entry_crq(n); | |
631 | ||
632 | if (sector < crq->rb_key) | |
633 | n = n->rb_left; | |
634 | else if (sector > crq->rb_key) | |
635 | n = n->rb_right; | |
636 | else | |
637 | return crq->request; | |
638 | } | |
639 | ||
640 | out: | |
641 | return NULL; | |
642 | } | |
643 | ||
b4878f24 | 644 | static void cfq_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 645 | { |
22e2c507 | 646 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 647 | |
b4878f24 | 648 | cfqd->rq_in_driver++; |
1da177e4 LT |
649 | } |
650 | ||
b4878f24 | 651 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 652 | { |
b4878f24 JA |
653 | struct cfq_data *cfqd = q->elevator->elevator_data; |
654 | ||
655 | WARN_ON(!cfqd->rq_in_driver); | |
656 | cfqd->rq_in_driver--; | |
1da177e4 LT |
657 | } |
658 | ||
b4878f24 | 659 | static void cfq_remove_request(struct request *rq) |
1da177e4 LT |
660 | { |
661 | struct cfq_rq *crq = RQ_DATA(rq); | |
662 | ||
b4878f24 JA |
663 | list_del_init(&rq->queuelist); |
664 | cfq_del_crq_rb(crq); | |
98b11471 | 665 | cfq_del_crq_hash(crq); |
1da177e4 LT |
666 | } |
667 | ||
668 | static int | |
669 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
670 | { | |
671 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
672 | struct request *__rq; | |
673 | int ret; | |
674 | ||
1da177e4 | 675 | __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); |
22e2c507 JA |
676 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
677 | ret = ELEVATOR_BACK_MERGE; | |
678 | goto out; | |
1da177e4 LT |
679 | } |
680 | ||
681 | __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio)); | |
22e2c507 JA |
682 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
683 | ret = ELEVATOR_FRONT_MERGE; | |
684 | goto out; | |
1da177e4 LT |
685 | } |
686 | ||
687 | return ELEVATOR_NO_MERGE; | |
688 | out: | |
1da177e4 LT |
689 | *req = __rq; |
690 | return ret; | |
691 | } | |
692 | ||
693 | static void cfq_merged_request(request_queue_t *q, struct request *req) | |
694 | { | |
695 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
696 | struct cfq_rq *crq = RQ_DATA(req); | |
697 | ||
698 | cfq_del_crq_hash(crq); | |
699 | cfq_add_crq_hash(cfqd, crq); | |
700 | ||
b4878f24 | 701 | if (rq_rb_key(req) != crq->rb_key) { |
1da177e4 LT |
702 | struct cfq_queue *cfqq = crq->cfq_queue; |
703 | ||
704 | cfq_update_next_crq(crq); | |
705 | cfq_reposition_crq_rb(cfqq, crq); | |
706 | } | |
1da177e4 LT |
707 | } |
708 | ||
709 | static void | |
710 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
711 | struct request *next) | |
712 | { | |
1da177e4 LT |
713 | cfq_merged_request(q, rq); |
714 | ||
22e2c507 JA |
715 | /* |
716 | * reposition in fifo if next is older than rq | |
717 | */ | |
718 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
719 | time_before(next->start_time, rq->start_time)) | |
720 | list_move(&rq->queuelist, &next->queuelist); | |
721 | ||
b4878f24 | 722 | cfq_remove_request(next); |
22e2c507 JA |
723 | } |
724 | ||
725 | static inline void | |
726 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
727 | { | |
728 | if (cfqq) { | |
729 | /* | |
730 | * stop potential idle class queues waiting service | |
731 | */ | |
732 | del_timer(&cfqd->idle_class_timer); | |
733 | ||
734 | cfqq->slice_start = jiffies; | |
735 | cfqq->slice_end = 0; | |
736 | cfqq->slice_left = 0; | |
3b18152c JA |
737 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
738 | cfq_clear_cfqq_fifo_expire(cfqq); | |
22e2c507 JA |
739 | } |
740 | ||
741 | cfqd->active_queue = cfqq; | |
742 | } | |
743 | ||
7b14e3b5 JA |
744 | /* |
745 | * current cfqq expired its slice (or was too idle), select new one | |
746 | */ | |
747 | static void | |
748 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
749 | int preempted) | |
750 | { | |
751 | unsigned long now = jiffies; | |
752 | ||
753 | if (cfq_cfqq_wait_request(cfqq)) | |
754 | del_timer(&cfqd->idle_slice_timer); | |
755 | ||
756 | if (!preempted && !cfq_cfqq_dispatched(cfqq)) { | |
757 | cfqq->service_last = now; | |
758 | cfq_schedule_dispatch(cfqd); | |
759 | } | |
760 | ||
761 | cfq_clear_cfqq_must_dispatch(cfqq); | |
762 | cfq_clear_cfqq_wait_request(cfqq); | |
763 | ||
764 | /* | |
765 | * store what was left of this slice, if the queue idled out | |
766 | * or was preempted | |
767 | */ | |
768 | if (time_after(cfqq->slice_end, now)) | |
769 | cfqq->slice_left = cfqq->slice_end - now; | |
770 | else | |
771 | cfqq->slice_left = 0; | |
772 | ||
773 | if (cfq_cfqq_on_rr(cfqq)) | |
774 | cfq_resort_rr_list(cfqq, preempted); | |
775 | ||
776 | if (cfqq == cfqd->active_queue) | |
777 | cfqd->active_queue = NULL; | |
778 | ||
779 | if (cfqd->active_cic) { | |
780 | put_io_context(cfqd->active_cic->ioc); | |
781 | cfqd->active_cic = NULL; | |
782 | } | |
783 | ||
784 | cfqd->dispatch_slice = 0; | |
785 | } | |
786 | ||
787 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
788 | { | |
789 | struct cfq_queue *cfqq = cfqd->active_queue; | |
790 | ||
791 | if (cfqq) | |
792 | __cfq_slice_expired(cfqd, cfqq, preempted); | |
793 | } | |
794 | ||
22e2c507 JA |
795 | /* |
796 | * 0 | |
797 | * 0,1 | |
798 | * 0,1,2 | |
799 | * 0,1,2,3 | |
800 | * 0,1,2,3,4 | |
801 | * 0,1,2,3,4,5 | |
802 | * 0,1,2,3,4,5,6 | |
803 | * 0,1,2,3,4,5,6,7 | |
804 | */ | |
805 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
806 | { | |
807 | int prio, wrap; | |
808 | ||
809 | prio = -1; | |
810 | wrap = 0; | |
811 | do { | |
812 | int p; | |
813 | ||
814 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
815 | if (!list_empty(&cfqd->rr_list[p])) { | |
816 | prio = p; | |
817 | break; | |
818 | } | |
819 | } | |
820 | ||
821 | if (prio != -1) | |
822 | break; | |
823 | cfqd->cur_prio = 0; | |
824 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
825 | cfqd->cur_end_prio = 0; | |
826 | if (wrap) | |
827 | break; | |
828 | wrap = 1; | |
1da177e4 | 829 | } |
22e2c507 JA |
830 | } while (1); |
831 | ||
832 | if (unlikely(prio == -1)) | |
833 | return -1; | |
834 | ||
835 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
836 | ||
837 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
838 | ||
839 | cfqd->cur_prio = prio + 1; | |
840 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
841 | cfqd->cur_end_prio = cfqd->cur_prio; | |
842 | cfqd->cur_prio = 0; | |
843 | } | |
844 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
845 | cfqd->cur_prio = 0; | |
846 | cfqd->cur_end_prio = 0; | |
1da177e4 LT |
847 | } |
848 | ||
22e2c507 JA |
849 | return prio; |
850 | } | |
851 | ||
3b18152c | 852 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
22e2c507 | 853 | { |
7b14e3b5 | 854 | struct cfq_queue *cfqq = NULL; |
22e2c507 JA |
855 | |
856 | /* | |
857 | * if current list is non-empty, grab first entry. if it is empty, | |
858 | * get next prio level and grab first entry then if any are spliced | |
859 | */ | |
860 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) | |
861 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
862 | ||
863 | /* | |
864 | * if we have idle queues and no rt or be queues had pending | |
865 | * requests, either allow immediate service if the grace period | |
866 | * has passed or arm the idle grace timer | |
867 | */ | |
868 | if (!cfqq && !list_empty(&cfqd->idle_rr)) { | |
869 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
870 | ||
871 | if (time_after_eq(jiffies, end)) | |
872 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
873 | else | |
874 | mod_timer(&cfqd->idle_class_timer, end); | |
875 | } | |
876 | ||
877 | __cfq_set_active_queue(cfqd, cfqq); | |
3b18152c | 878 | return cfqq; |
22e2c507 JA |
879 | } |
880 | ||
22e2c507 JA |
881 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
882 | ||
883 | { | |
7b14e3b5 JA |
884 | unsigned long sl; |
885 | ||
22e2c507 JA |
886 | WARN_ON(!RB_EMPTY(&cfqq->sort_list)); |
887 | WARN_ON(cfqq != cfqd->active_queue); | |
888 | ||
889 | /* | |
890 | * idle is disabled, either manually or by past process history | |
891 | */ | |
892 | if (!cfqd->cfq_slice_idle) | |
893 | return 0; | |
3b18152c | 894 | if (!cfq_cfqq_idle_window(cfqq)) |
22e2c507 JA |
895 | return 0; |
896 | /* | |
897 | * task has exited, don't wait | |
898 | */ | |
899 | if (cfqd->active_cic && !cfqd->active_cic->ioc->task) | |
900 | return 0; | |
901 | ||
3b18152c JA |
902 | cfq_mark_cfqq_must_dispatch(cfqq); |
903 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 904 | |
7b14e3b5 JA |
905 | sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); |
906 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); | |
22e2c507 | 907 | return 1; |
1da177e4 LT |
908 | } |
909 | ||
b4878f24 | 910 | static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) |
1da177e4 LT |
911 | { |
912 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
913 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 JA |
914 | |
915 | cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); | |
b4878f24 | 916 | cfq_remove_request(crq->request); |
3b18152c | 917 | cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; |
b4878f24 | 918 | elv_dispatch_sort(q, crq->request); |
1da177e4 LT |
919 | } |
920 | ||
921 | /* | |
922 | * return expired entry, or NULL to just start from scratch in rbtree | |
923 | */ | |
924 | static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) | |
925 | { | |
926 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 927 | struct request *rq; |
1da177e4 LT |
928 | struct cfq_rq *crq; |
929 | ||
3b18152c | 930 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 LT |
931 | return NULL; |
932 | ||
22e2c507 | 933 | if (!list_empty(&cfqq->fifo)) { |
3b18152c | 934 | int fifo = cfq_cfqq_class_sync(cfqq); |
1da177e4 | 935 | |
22e2c507 JA |
936 | crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); |
937 | rq = crq->request; | |
938 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
3b18152c | 939 | cfq_mark_cfqq_fifo_expire(cfqq); |
22e2c507 JA |
940 | return crq; |
941 | } | |
1da177e4 LT |
942 | } |
943 | ||
944 | return NULL; | |
945 | } | |
946 | ||
947 | /* | |
3b18152c JA |
948 | * Scale schedule slice based on io priority. Use the sync time slice only |
949 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
950 | * io only, should not get full sync slice length. | |
1da177e4 | 951 | */ |
22e2c507 JA |
952 | static inline int |
953 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
954 | { | |
955 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
956 | ||
957 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
958 | ||
959 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
960 | } | |
961 | ||
1da177e4 | 962 | static inline void |
22e2c507 | 963 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 964 | { |
22e2c507 JA |
965 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
966 | } | |
1da177e4 | 967 | |
22e2c507 JA |
968 | static inline int |
969 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
970 | { | |
971 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 972 | |
22e2c507 | 973 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 974 | |
22e2c507 | 975 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
976 | } |
977 | ||
22e2c507 JA |
978 | /* |
979 | * get next queue for service | |
980 | */ | |
1b5ed5e1 | 981 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 982 | { |
22e2c507 | 983 | unsigned long now = jiffies; |
1da177e4 | 984 | struct cfq_queue *cfqq; |
1da177e4 | 985 | |
22e2c507 JA |
986 | cfqq = cfqd->active_queue; |
987 | if (!cfqq) | |
988 | goto new_queue; | |
1da177e4 | 989 | |
22e2c507 JA |
990 | /* |
991 | * slice has expired | |
992 | */ | |
3b18152c JA |
993 | if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) |
994 | goto expire; | |
1da177e4 | 995 | |
22e2c507 JA |
996 | /* |
997 | * if queue has requests, dispatch one. if not, check if | |
998 | * enough slice is left to wait for one | |
999 | */ | |
1000 | if (!RB_EMPTY(&cfqq->sort_list)) | |
1001 | goto keep_queue; | |
1b5ed5e1 | 1002 | else if (cfq_cfqq_class_sync(cfqq) && |
22e2c507 JA |
1003 | time_before(now, cfqq->slice_end)) { |
1004 | if (cfq_arm_slice_timer(cfqd, cfqq)) | |
1005 | return NULL; | |
1006 | } | |
1007 | ||
3b18152c | 1008 | expire: |
22e2c507 | 1009 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
1010 | new_queue: |
1011 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 1012 | keep_queue: |
3b18152c | 1013 | return cfqq; |
22e2c507 JA |
1014 | } |
1015 | ||
1016 | static int | |
1017 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1018 | int max_dispatch) | |
1019 | { | |
1020 | int dispatched = 0; | |
1021 | ||
1022 | BUG_ON(RB_EMPTY(&cfqq->sort_list)); | |
1023 | ||
1024 | do { | |
1025 | struct cfq_rq *crq; | |
1da177e4 LT |
1026 | |
1027 | /* | |
22e2c507 | 1028 | * follow expired path, else get first next available |
1da177e4 | 1029 | */ |
22e2c507 JA |
1030 | if ((crq = cfq_check_fifo(cfqq)) == NULL) |
1031 | crq = cfqq->next_crq; | |
1032 | ||
1033 | /* | |
1034 | * finally, insert request into driver dispatch list | |
1035 | */ | |
b4878f24 | 1036 | cfq_dispatch_insert(cfqd->queue, crq); |
1da177e4 | 1037 | |
22e2c507 JA |
1038 | cfqd->dispatch_slice++; |
1039 | dispatched++; | |
1da177e4 | 1040 | |
22e2c507 JA |
1041 | if (!cfqd->active_cic) { |
1042 | atomic_inc(&crq->io_context->ioc->refcount); | |
1043 | cfqd->active_cic = crq->io_context; | |
1044 | } | |
1da177e4 | 1045 | |
22e2c507 JA |
1046 | if (RB_EMPTY(&cfqq->sort_list)) |
1047 | break; | |
1048 | ||
1049 | } while (dispatched < max_dispatch); | |
1050 | ||
1051 | /* | |
1052 | * if slice end isn't set yet, set it. if at least one request was | |
1053 | * sync, use the sync time slice value | |
1054 | */ | |
1055 | if (!cfqq->slice_end) | |
1056 | cfq_set_prio_slice(cfqd, cfqq); | |
1057 | ||
1058 | /* | |
1059 | * expire an async queue immediately if it has used up its slice. idle | |
1060 | * queue always expire after 1 dispatch round. | |
1061 | */ | |
1062 | if ((!cfq_cfqq_sync(cfqq) && | |
1063 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1064 | cfq_class_idle(cfqq)) | |
1065 | cfq_slice_expired(cfqd, 0); | |
1066 | ||
1067 | return dispatched; | |
1068 | } | |
1069 | ||
1b5ed5e1 TH |
1070 | static int |
1071 | cfq_forced_dispatch_cfqqs(struct list_head *list) | |
1072 | { | |
1073 | int dispatched = 0; | |
1074 | struct cfq_queue *cfqq, *next; | |
1075 | struct cfq_rq *crq; | |
1076 | ||
1077 | list_for_each_entry_safe(cfqq, next, list, cfq_list) { | |
1078 | while ((crq = cfqq->next_crq)) { | |
1079 | cfq_dispatch_insert(cfqq->cfqd->queue, crq); | |
1080 | dispatched++; | |
1081 | } | |
1082 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1083 | } | |
1084 | return dispatched; | |
1085 | } | |
1086 | ||
1087 | static int | |
1088 | cfq_forced_dispatch(struct cfq_data *cfqd) | |
1089 | { | |
1090 | int i, dispatched = 0; | |
1091 | ||
1092 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
1093 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]); | |
1094 | ||
1095 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr); | |
1096 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); | |
1097 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
1098 | ||
1099 | cfq_slice_expired(cfqd, 0); | |
1100 | ||
1101 | BUG_ON(cfqd->busy_queues); | |
1102 | ||
1103 | return dispatched; | |
1104 | } | |
1105 | ||
22e2c507 | 1106 | static int |
b4878f24 | 1107 | cfq_dispatch_requests(request_queue_t *q, int force) |
22e2c507 JA |
1108 | { |
1109 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1110 | struct cfq_queue *cfqq; | |
1111 | ||
1112 | if (!cfqd->busy_queues) | |
1113 | return 0; | |
1114 | ||
1b5ed5e1 TH |
1115 | if (unlikely(force)) |
1116 | return cfq_forced_dispatch(cfqd); | |
1117 | ||
1118 | cfqq = cfq_select_queue(cfqd); | |
22e2c507 | 1119 | if (cfqq) { |
b4878f24 JA |
1120 | int max_dispatch; |
1121 | ||
1122 | /* | |
1123 | * if idle window is disabled, allow queue buildup | |
1124 | */ | |
1125 | if (!cfq_cfqq_idle_window(cfqq) && | |
1126 | cfqd->rq_in_driver >= cfqd->cfq_max_depth) | |
1127 | return 0; | |
1128 | ||
3b18152c JA |
1129 | cfq_clear_cfqq_must_dispatch(cfqq); |
1130 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1131 | del_timer(&cfqd->idle_slice_timer); |
1132 | ||
1b5ed5e1 TH |
1133 | max_dispatch = cfqd->cfq_quantum; |
1134 | if (cfq_class_idle(cfqq)) | |
1135 | max_dispatch = 1; | |
1da177e4 | 1136 | |
22e2c507 | 1137 | return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1138 | } |
1139 | ||
22e2c507 | 1140 | return 0; |
1da177e4 LT |
1141 | } |
1142 | ||
1da177e4 LT |
1143 | /* |
1144 | * task holds one reference to the queue, dropped when task exits. each crq | |
1145 | * in-flight on this queue also holds a reference, dropped when crq is freed. | |
1146 | * | |
1147 | * queue lock must be held here. | |
1148 | */ | |
1149 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1150 | { | |
22e2c507 JA |
1151 | struct cfq_data *cfqd = cfqq->cfqd; |
1152 | ||
1153 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1154 | |
1155 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1156 | return; | |
1157 | ||
1158 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1159 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1160 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1161 | |
7b14e3b5 | 1162 | if (unlikely(cfqd->active_queue == cfqq)) |
3b18152c | 1163 | __cfq_slice_expired(cfqd, cfqq, 0); |
22e2c507 | 1164 | |
1da177e4 LT |
1165 | cfq_put_cfqd(cfqq->cfqd); |
1166 | ||
1167 | /* | |
1168 | * it's on the empty list and still hashed | |
1169 | */ | |
1170 | list_del(&cfqq->cfq_list); | |
1171 | hlist_del(&cfqq->cfq_hash); | |
1172 | kmem_cache_free(cfq_pool, cfqq); | |
1173 | } | |
1174 | ||
1175 | static inline struct cfq_queue * | |
3b18152c JA |
1176 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, |
1177 | const int hashval) | |
1da177e4 LT |
1178 | { |
1179 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
1180 | struct hlist_node *entry, *next; | |
1181 | ||
1182 | hlist_for_each_safe(entry, next, hash_list) { | |
1183 | struct cfq_queue *__cfqq = list_entry_qhash(entry); | |
b0a6916b | 1184 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); |
1da177e4 | 1185 | |
3b18152c | 1186 | if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY)) |
1da177e4 LT |
1187 | return __cfqq; |
1188 | } | |
1189 | ||
1190 | return NULL; | |
1191 | } | |
1192 | ||
1193 | static struct cfq_queue * | |
3b18152c | 1194 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) |
1da177e4 | 1195 | { |
3b18152c | 1196 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); |
1da177e4 LT |
1197 | } |
1198 | ||
22e2c507 | 1199 | static void cfq_free_io_context(struct cfq_io_context *cic) |
1da177e4 | 1200 | { |
22e2c507 JA |
1201 | struct cfq_io_context *__cic; |
1202 | struct list_head *entry, *next; | |
1da177e4 | 1203 | |
22e2c507 JA |
1204 | list_for_each_safe(entry, next, &cic->list) { |
1205 | __cic = list_entry(entry, struct cfq_io_context, list); | |
1206 | kmem_cache_free(cfq_ioc_pool, __cic); | |
1da177e4 LT |
1207 | } |
1208 | ||
22e2c507 | 1209 | kmem_cache_free(cfq_ioc_pool, cic); |
1da177e4 LT |
1210 | } |
1211 | ||
22e2c507 JA |
1212 | /* |
1213 | * Called with interrupts disabled | |
1214 | */ | |
1215 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1da177e4 | 1216 | { |
478a82b0 | 1217 | struct cfq_data *cfqd = cic->key; |
22e2c507 JA |
1218 | request_queue_t *q = cfqd->queue; |
1219 | ||
1220 | WARN_ON(!irqs_disabled()); | |
1221 | ||
1222 | spin_lock(q->queue_lock); | |
1223 | ||
12a05732 AV |
1224 | if (cic->cfqq[ASYNC]) { |
1225 | if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue)) | |
1226 | __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0); | |
1227 | cfq_put_queue(cic->cfqq[ASYNC]); | |
1228 | cic->cfqq[ASYNC] = NULL; | |
1229 | } | |
1230 | ||
1231 | if (cic->cfqq[SYNC]) { | |
1232 | if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue)) | |
1233 | __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0); | |
1234 | cfq_put_queue(cic->cfqq[SYNC]); | |
1235 | cic->cfqq[SYNC] = NULL; | |
1236 | } | |
22e2c507 | 1237 | |
478a82b0 | 1238 | cic->key = NULL; |
22e2c507 | 1239 | spin_unlock(q->queue_lock); |
1da177e4 LT |
1240 | } |
1241 | ||
1242 | /* | |
22e2c507 JA |
1243 | * Another task may update the task cic list, if it is doing a queue lookup |
1244 | * on its behalf. cfq_cic_lock excludes such concurrent updates | |
1da177e4 LT |
1245 | */ |
1246 | static void cfq_exit_io_context(struct cfq_io_context *cic) | |
1247 | { | |
22e2c507 JA |
1248 | struct cfq_io_context *__cic; |
1249 | struct list_head *entry; | |
1da177e4 LT |
1250 | unsigned long flags; |
1251 | ||
22e2c507 JA |
1252 | local_irq_save(flags); |
1253 | ||
1da177e4 LT |
1254 | /* |
1255 | * put the reference this task is holding to the various queues | |
1256 | */ | |
22e2c507 | 1257 | list_for_each(entry, &cic->list) { |
1da177e4 | 1258 | __cic = list_entry(entry, struct cfq_io_context, list); |
22e2c507 | 1259 | cfq_exit_single_io_context(__cic); |
1da177e4 LT |
1260 | } |
1261 | ||
22e2c507 JA |
1262 | cfq_exit_single_io_context(cic); |
1263 | local_irq_restore(flags); | |
1da177e4 LT |
1264 | } |
1265 | ||
22e2c507 | 1266 | static struct cfq_io_context * |
8267e268 | 1267 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1268 | { |
22e2c507 | 1269 | struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); |
1da177e4 LT |
1270 | |
1271 | if (cic) { | |
1da177e4 | 1272 | INIT_LIST_HEAD(&cic->list); |
12a05732 AV |
1273 | cic->cfqq[ASYNC] = NULL; |
1274 | cic->cfqq[SYNC] = NULL; | |
22e2c507 JA |
1275 | cic->key = NULL; |
1276 | cic->last_end_request = jiffies; | |
1277 | cic->ttime_total = 0; | |
1278 | cic->ttime_samples = 0; | |
1279 | cic->ttime_mean = 0; | |
1280 | cic->dtor = cfq_free_io_context; | |
1281 | cic->exit = cfq_exit_io_context; | |
1da177e4 LT |
1282 | } |
1283 | ||
1284 | return cic; | |
1285 | } | |
1286 | ||
22e2c507 JA |
1287 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1288 | { | |
1289 | struct task_struct *tsk = current; | |
1290 | int ioprio_class; | |
1291 | ||
3b18152c | 1292 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1293 | return; |
1294 | ||
1295 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1296 | switch (ioprio_class) { | |
1297 | default: | |
1298 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1299 | case IOPRIO_CLASS_NONE: | |
1300 | /* | |
1301 | * no prio set, place us in the middle of the BE classes | |
1302 | */ | |
1303 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1304 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1305 | break; | |
1306 | case IOPRIO_CLASS_RT: | |
1307 | cfqq->ioprio = task_ioprio(tsk); | |
1308 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1309 | break; | |
1310 | case IOPRIO_CLASS_BE: | |
1311 | cfqq->ioprio = task_ioprio(tsk); | |
1312 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1313 | break; | |
1314 | case IOPRIO_CLASS_IDLE: | |
1315 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1316 | cfqq->ioprio = 7; | |
3b18152c | 1317 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1318 | break; |
1319 | } | |
1320 | ||
1321 | /* | |
1322 | * keep track of original prio settings in case we have to temporarily | |
1323 | * elevate the priority of this queue | |
1324 | */ | |
1325 | cfqq->org_ioprio = cfqq->ioprio; | |
1326 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1327 | ||
3b18152c | 1328 | if (cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1329 | cfq_resort_rr_list(cfqq, 0); |
1330 | ||
3b18152c | 1331 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1332 | } |
1333 | ||
478a82b0 | 1334 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1335 | { |
478a82b0 AV |
1336 | struct cfq_data *cfqd = cic->key; |
1337 | struct cfq_queue *cfqq; | |
1338 | if (cfqd) { | |
22e2c507 | 1339 | spin_lock(cfqd->queue->queue_lock); |
12a05732 AV |
1340 | cfqq = cic->cfqq[ASYNC]; |
1341 | if (cfqq) { | |
1342 | cfq_mark_cfqq_prio_changed(cfqq); | |
1343 | cfq_init_prio_data(cfqq); | |
1344 | } | |
1345 | cfqq = cic->cfqq[SYNC]; | |
478a82b0 AV |
1346 | if (cfqq) { |
1347 | cfq_mark_cfqq_prio_changed(cfqq); | |
1348 | cfq_init_prio_data(cfqq); | |
1349 | } | |
22e2c507 JA |
1350 | spin_unlock(cfqd->queue->queue_lock); |
1351 | } | |
1352 | } | |
1353 | ||
1354 | /* | |
1355 | * callback from sys_ioprio_set, irqs are disabled | |
1356 | */ | |
1357 | static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) | |
1358 | { | |
a6a0763a AV |
1359 | struct cfq_io_context *cic; |
1360 | ||
1361 | write_lock(&cfq_exit_lock); | |
1362 | ||
1363 | cic = ioc->cic; | |
22e2c507 | 1364 | |
478a82b0 | 1365 | changed_ioprio(cic); |
22e2c507 JA |
1366 | |
1367 | list_for_each_entry(cic, &cic->list, list) | |
478a82b0 | 1368 | changed_ioprio(cic); |
22e2c507 | 1369 | |
a6a0763a AV |
1370 | write_unlock(&cfq_exit_lock); |
1371 | ||
22e2c507 JA |
1372 | return 0; |
1373 | } | |
1374 | ||
1375 | static struct cfq_queue * | |
3b18152c | 1376 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio, |
8267e268 | 1377 | gfp_t gfp_mask) |
22e2c507 JA |
1378 | { |
1379 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1380 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
1381 | ||
1382 | retry: | |
3b18152c | 1383 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); |
22e2c507 JA |
1384 | |
1385 | if (!cfqq) { | |
1386 | if (new_cfqq) { | |
1387 | cfqq = new_cfqq; | |
1388 | new_cfqq = NULL; | |
1389 | } else if (gfp_mask & __GFP_WAIT) { | |
1390 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1391 | new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1392 | spin_lock_irq(cfqd->queue->queue_lock); | |
1393 | goto retry; | |
1394 | } else { | |
1395 | cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1396 | if (!cfqq) | |
1397 | goto out; | |
1398 | } | |
1399 | ||
1400 | memset(cfqq, 0, sizeof(*cfqq)); | |
1401 | ||
1402 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1403 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
1404 | RB_CLEAR_ROOT(&cfqq->sort_list); | |
1405 | INIT_LIST_HEAD(&cfqq->fifo); | |
1406 | ||
1407 | cfqq->key = key; | |
1408 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1409 | atomic_set(&cfqq->ref, 0); | |
1410 | cfqq->cfqd = cfqd; | |
1411 | atomic_inc(&cfqd->ref); | |
1412 | cfqq->service_last = 0; | |
1413 | /* | |
1414 | * set ->slice_left to allow preemption for a new process | |
1415 | */ | |
1416 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
3b18152c JA |
1417 | cfq_mark_cfqq_idle_window(cfqq); |
1418 | cfq_mark_cfqq_prio_changed(cfqq); | |
1419 | cfq_init_prio_data(cfqq); | |
22e2c507 JA |
1420 | } |
1421 | ||
1422 | if (new_cfqq) | |
1423 | kmem_cache_free(cfq_pool, new_cfqq); | |
1424 | ||
1425 | atomic_inc(&cfqq->ref); | |
1426 | out: | |
1427 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1428 | return cfqq; | |
1429 | } | |
1430 | ||
1da177e4 LT |
1431 | /* |
1432 | * Setup general io context and cfq io context. There can be several cfq | |
1433 | * io contexts per general io context, if this process is doing io to more | |
1434 | * than one device managed by cfq. Note that caller is holding a reference to | |
1435 | * cfqq, so we don't need to worry about it disappearing | |
1436 | */ | |
1437 | static struct cfq_io_context * | |
8267e268 | 1438 | cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask) |
1da177e4 | 1439 | { |
22e2c507 | 1440 | struct io_context *ioc = NULL; |
1da177e4 | 1441 | struct cfq_io_context *cic; |
1da177e4 | 1442 | |
22e2c507 | 1443 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1444 | |
22e2c507 | 1445 | ioc = get_io_context(gfp_mask); |
1da177e4 LT |
1446 | if (!ioc) |
1447 | return NULL; | |
1448 | ||
1449 | if ((cic = ioc->cic) == NULL) { | |
22e2c507 | 1450 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1da177e4 LT |
1451 | |
1452 | if (cic == NULL) | |
1453 | goto err; | |
1454 | ||
22e2c507 JA |
1455 | /* |
1456 | * manually increment generic io_context usage count, it | |
1457 | * cannot go away since we are already holding one ref to it | |
1458 | */ | |
1da177e4 | 1459 | cic->ioc = ioc; |
22e2c507 | 1460 | cic->key = cfqd; |
a6a0763a | 1461 | read_lock(&cfq_exit_lock); |
478a82b0 AV |
1462 | ioc->set_ioprio = cfq_ioc_set_ioprio; |
1463 | ioc->cic = cic; | |
a6a0763a | 1464 | read_unlock(&cfq_exit_lock); |
1da177e4 LT |
1465 | } else { |
1466 | struct cfq_io_context *__cic; | |
1da177e4 LT |
1467 | |
1468 | /* | |
22e2c507 | 1469 | * the first cic on the list is actually the head itself |
1da177e4 | 1470 | */ |
22e2c507 | 1471 | if (cic->key == cfqd) |
1da177e4 LT |
1472 | goto out; |
1473 | ||
1474 | /* | |
1475 | * cic exists, check if we already are there. linear search | |
1476 | * should be ok here, the list will usually not be more than | |
1477 | * 1 or a few entries long | |
1478 | */ | |
1da177e4 LT |
1479 | list_for_each_entry(__cic, &cic->list, list) { |
1480 | /* | |
1481 | * this process is already holding a reference to | |
1482 | * this queue, so no need to get one more | |
1483 | */ | |
22e2c507 | 1484 | if (__cic->key == cfqd) { |
1da177e4 | 1485 | cic = __cic; |
1da177e4 LT |
1486 | goto out; |
1487 | } | |
1488 | } | |
1da177e4 LT |
1489 | |
1490 | /* | |
1491 | * nope, process doesn't have a cic assoicated with this | |
1492 | * cfqq yet. get a new one and add to list | |
1493 | */ | |
22e2c507 | 1494 | __cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1da177e4 LT |
1495 | if (__cic == NULL) |
1496 | goto err; | |
1497 | ||
1498 | __cic->ioc = ioc; | |
22e2c507 | 1499 | __cic->key = cfqd; |
a6a0763a | 1500 | read_lock(&cfq_exit_lock); |
1da177e4 | 1501 | list_add(&__cic->list, &cic->list); |
a6a0763a | 1502 | read_unlock(&cfq_exit_lock); |
1da177e4 | 1503 | cic = __cic; |
1da177e4 LT |
1504 | } |
1505 | ||
1506 | out: | |
1da177e4 LT |
1507 | return cic; |
1508 | err: | |
1509 | put_io_context(ioc); | |
1510 | return NULL; | |
1511 | } | |
1512 | ||
22e2c507 JA |
1513 | static void |
1514 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1515 | { |
22e2c507 | 1516 | unsigned long elapsed, ttime; |
1da177e4 | 1517 | |
22e2c507 JA |
1518 | /* |
1519 | * if this context already has stuff queued, thinktime is from | |
1520 | * last queue not last end | |
1521 | */ | |
1522 | #if 0 | |
1523 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1524 | elapsed = jiffies - cic->last_end_request; | |
1525 | else | |
1526 | elapsed = jiffies - cic->last_queue; | |
1527 | #else | |
1528 | elapsed = jiffies - cic->last_end_request; | |
1529 | #endif | |
1da177e4 | 1530 | |
22e2c507 | 1531 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
db3b5848 | 1532 | |
22e2c507 JA |
1533 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1534 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1535 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1536 | } | |
1da177e4 | 1537 | |
22e2c507 | 1538 | #define sample_valid(samples) ((samples) > 80) |
1da177e4 | 1539 | |
22e2c507 JA |
1540 | /* |
1541 | * Disable idle window if the process thinks too long or seeks so much that | |
1542 | * it doesn't matter | |
1543 | */ | |
1544 | static void | |
1545 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1546 | struct cfq_io_context *cic) | |
1547 | { | |
3b18152c | 1548 | int enable_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1549 | |
22e2c507 JA |
1550 | if (!cic->ioc->task || !cfqd->cfq_slice_idle) |
1551 | enable_idle = 0; | |
1552 | else if (sample_valid(cic->ttime_samples)) { | |
1553 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1554 | enable_idle = 0; | |
1555 | else | |
1556 | enable_idle = 1; | |
1da177e4 LT |
1557 | } |
1558 | ||
3b18152c JA |
1559 | if (enable_idle) |
1560 | cfq_mark_cfqq_idle_window(cfqq); | |
1561 | else | |
1562 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1563 | } |
1da177e4 | 1564 | |
22e2c507 JA |
1565 | |
1566 | /* | |
1567 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1568 | * no or if we aren't sure, a 1 will cause a preempt. | |
1569 | */ | |
1570 | static int | |
1571 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1572 | struct cfq_rq *crq) | |
1573 | { | |
1574 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1575 | ||
1576 | if (cfq_class_idle(new_cfqq)) | |
1577 | return 0; | |
1578 | ||
1579 | if (!cfqq) | |
1580 | return 1; | |
1581 | ||
1582 | if (cfq_class_idle(cfqq)) | |
1583 | return 1; | |
3b18152c | 1584 | if (!cfq_cfqq_wait_request(new_cfqq)) |
22e2c507 JA |
1585 | return 0; |
1586 | /* | |
1587 | * if it doesn't have slice left, forget it | |
1588 | */ | |
1589 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1590 | return 0; | |
3b18152c | 1591 | if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 JA |
1592 | return 1; |
1593 | ||
1594 | return 0; | |
1595 | } | |
1596 | ||
1597 | /* | |
1598 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1599 | * let it have half of its nominal slice. | |
1600 | */ | |
1601 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1602 | { | |
1603 | struct cfq_queue *__cfqq, *next; | |
1604 | ||
1605 | list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) | |
1606 | cfq_resort_rr_list(__cfqq, 1); | |
1607 | ||
1608 | if (!cfqq->slice_left) | |
1609 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1610 | ||
1611 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
3b18152c | 1612 | __cfq_slice_expired(cfqd, cfqq, 1); |
22e2c507 JA |
1613 | __cfq_set_active_queue(cfqd, cfqq); |
1614 | } | |
1615 | ||
1616 | /* | |
1617 | * should really be a ll_rw_blk.c helper | |
1618 | */ | |
1619 | static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1620 | { | |
1621 | request_queue_t *q = cfqd->queue; | |
1622 | ||
1623 | if (!blk_queue_plugged(q)) | |
1624 | q->request_fn(q); | |
1625 | else | |
1626 | __generic_unplug_device(q); | |
1627 | } | |
1628 | ||
1629 | /* | |
1630 | * Called when a new fs request (crq) is added (to cfqq). Check if there's | |
1631 | * something we should do about it | |
1632 | */ | |
1633 | static void | |
1634 | cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1635 | struct cfq_rq *crq) | |
1636 | { | |
9c2c38a1 | 1637 | struct cfq_io_context *cic; |
22e2c507 JA |
1638 | |
1639 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
1640 | ||
9c2c38a1 JA |
1641 | /* |
1642 | * we never wait for an async request and we don't allow preemption | |
1643 | * of an async request. so just return early | |
1644 | */ | |
1645 | if (!cfq_crq_is_sync(crq)) | |
1646 | return; | |
22e2c507 | 1647 | |
9c2c38a1 | 1648 | cic = crq->io_context; |
22e2c507 | 1649 | |
9c2c38a1 JA |
1650 | cfq_update_io_thinktime(cfqd, cic); |
1651 | cfq_update_idle_window(cfqd, cfqq, cic); | |
1652 | ||
1653 | cic->last_queue = jiffies; | |
22e2c507 JA |
1654 | |
1655 | if (cfqq == cfqd->active_queue) { | |
1656 | /* | |
1657 | * if we are waiting for a request for this queue, let it rip | |
1658 | * immediately and flag that we must not expire this queue | |
1659 | * just now | |
1660 | */ | |
3b18152c JA |
1661 | if (cfq_cfqq_wait_request(cfqq)) { |
1662 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 JA |
1663 | del_timer(&cfqd->idle_slice_timer); |
1664 | cfq_start_queueing(cfqd, cfqq); | |
1665 | } | |
1666 | } else if (cfq_should_preempt(cfqd, cfqq, crq)) { | |
1667 | /* | |
1668 | * not the active queue - expire current slice if it is | |
1669 | * idle and has expired it's mean thinktime or this new queue | |
1670 | * has some old slice time left and is of higher priority | |
1671 | */ | |
1672 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1673 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
1674 | cfq_start_queueing(cfqd, cfqq); |
1675 | } | |
1da177e4 LT |
1676 | } |
1677 | ||
b4878f24 | 1678 | static void cfq_insert_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1679 | { |
b4878f24 | 1680 | struct cfq_data *cfqd = q->elevator->elevator_data; |
22e2c507 JA |
1681 | struct cfq_rq *crq = RQ_DATA(rq); |
1682 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1683 | ||
1684 | cfq_init_prio_data(cfqq); | |
1da177e4 LT |
1685 | |
1686 | cfq_add_crq_rb(crq); | |
1da177e4 | 1687 | |
22e2c507 JA |
1688 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1689 | ||
98b11471 | 1690 | if (rq_mergeable(rq)) |
22e2c507 JA |
1691 | cfq_add_crq_hash(cfqd, crq); |
1692 | ||
22e2c507 | 1693 | cfq_crq_enqueued(cfqd, cfqq, crq); |
1da177e4 LT |
1694 | } |
1695 | ||
1da177e4 LT |
1696 | static void cfq_completed_request(request_queue_t *q, struct request *rq) |
1697 | { | |
1698 | struct cfq_rq *crq = RQ_DATA(rq); | |
b4878f24 JA |
1699 | struct cfq_queue *cfqq = crq->cfq_queue; |
1700 | struct cfq_data *cfqd = cfqq->cfqd; | |
1701 | const int sync = cfq_crq_is_sync(crq); | |
1702 | unsigned long now; | |
1da177e4 | 1703 | |
b4878f24 | 1704 | now = jiffies; |
1da177e4 | 1705 | |
b4878f24 JA |
1706 | WARN_ON(!cfqd->rq_in_driver); |
1707 | WARN_ON(!cfqq->on_dispatch[sync]); | |
1708 | cfqd->rq_in_driver--; | |
1709 | cfqq->on_dispatch[sync]--; | |
1da177e4 | 1710 | |
b4878f24 JA |
1711 | if (!cfq_class_idle(cfqq)) |
1712 | cfqd->last_end_request = now; | |
3b18152c | 1713 | |
b4878f24 JA |
1714 | if (!cfq_cfqq_dispatched(cfqq)) { |
1715 | if (cfq_cfqq_on_rr(cfqq)) { | |
1716 | cfqq->service_last = now; | |
1717 | cfq_resort_rr_list(cfqq, 0); | |
1718 | } | |
7b14e3b5 | 1719 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1720 | } |
1721 | ||
b4878f24 JA |
1722 | if (cfq_crq_is_sync(crq)) |
1723 | crq->io_context->last_end_request = now; | |
1da177e4 LT |
1724 | } |
1725 | ||
1726 | static struct request * | |
1727 | cfq_former_request(request_queue_t *q, struct request *rq) | |
1728 | { | |
1729 | struct cfq_rq *crq = RQ_DATA(rq); | |
1730 | struct rb_node *rbprev = rb_prev(&crq->rb_node); | |
1731 | ||
1732 | if (rbprev) | |
1733 | return rb_entry_crq(rbprev)->request; | |
1734 | ||
1735 | return NULL; | |
1736 | } | |
1737 | ||
1738 | static struct request * | |
1739 | cfq_latter_request(request_queue_t *q, struct request *rq) | |
1740 | { | |
1741 | struct cfq_rq *crq = RQ_DATA(rq); | |
1742 | struct rb_node *rbnext = rb_next(&crq->rb_node); | |
1743 | ||
1744 | if (rbnext) | |
1745 | return rb_entry_crq(rbnext)->request; | |
1746 | ||
1747 | return NULL; | |
1748 | } | |
1749 | ||
22e2c507 JA |
1750 | /* |
1751 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1752 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1753 | */ | |
1754 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1755 | { |
22e2c507 JA |
1756 | const int ioprio_class = cfqq->ioprio_class; |
1757 | const int ioprio = cfqq->ioprio; | |
1da177e4 | 1758 | |
22e2c507 JA |
1759 | if (has_fs_excl()) { |
1760 | /* | |
1761 | * boost idle prio on transactions that would lock out other | |
1762 | * users of the filesystem | |
1763 | */ | |
1764 | if (cfq_class_idle(cfqq)) | |
1765 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1766 | if (cfqq->ioprio > IOPRIO_NORM) | |
1767 | cfqq->ioprio = IOPRIO_NORM; | |
1768 | } else { | |
1769 | /* | |
1770 | * check if we need to unboost the queue | |
1771 | */ | |
1772 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1773 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1774 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1775 | cfqq->ioprio = cfqq->org_ioprio; | |
1776 | } | |
1da177e4 | 1777 | |
22e2c507 JA |
1778 | /* |
1779 | * refile between round-robin lists if we moved the priority class | |
1780 | */ | |
1781 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
3b18152c | 1782 | cfq_cfqq_on_rr(cfqq)) |
22e2c507 JA |
1783 | cfq_resort_rr_list(cfqq, 0); |
1784 | } | |
1da177e4 | 1785 | |
22e2c507 JA |
1786 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) |
1787 | { | |
1788 | if (rw == READ || process_sync(task)) | |
1789 | return task->pid; | |
1da177e4 | 1790 | |
22e2c507 JA |
1791 | return CFQ_KEY_ASYNC; |
1792 | } | |
1da177e4 | 1793 | |
22e2c507 JA |
1794 | static inline int |
1795 | __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1796 | struct task_struct *task, int rw) | |
1797 | { | |
3b18152c JA |
1798 | #if 1 |
1799 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && | |
99f95e52 | 1800 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1801 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1802 | return ELV_MQUEUE_MUST; |
3b18152c | 1803 | } |
1da177e4 | 1804 | |
22e2c507 | 1805 | return ELV_MQUEUE_MAY; |
3b18152c | 1806 | #else |
22e2c507 JA |
1807 | if (!cfqq || task->flags & PF_MEMALLOC) |
1808 | return ELV_MQUEUE_MAY; | |
3b18152c JA |
1809 | if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { |
1810 | if (cfq_cfqq_wait_request(cfqq)) | |
22e2c507 | 1811 | return ELV_MQUEUE_MUST; |
1da177e4 | 1812 | |
22e2c507 JA |
1813 | /* |
1814 | * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we | |
1815 | * can quickly flood the queue with writes from a single task | |
1816 | */ | |
99f95e52 | 1817 | if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1818 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1819 | return ELV_MQUEUE_MUST; |
1da177e4 | 1820 | } |
22e2c507 JA |
1821 | |
1822 | return ELV_MQUEUE_MAY; | |
1da177e4 | 1823 | } |
22e2c507 JA |
1824 | if (cfq_class_idle(cfqq)) |
1825 | return ELV_MQUEUE_NO; | |
1826 | if (cfqq->allocated[rw] >= cfqd->max_queued) { | |
1827 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
1828 | int ret = ELV_MQUEUE_NO; | |
1da177e4 | 1829 | |
22e2c507 JA |
1830 | if (ioc && ioc->nr_batch_requests) |
1831 | ret = ELV_MQUEUE_MAY; | |
1832 | ||
1833 | put_io_context(ioc); | |
1834 | return ret; | |
1835 | } | |
1836 | ||
1837 | return ELV_MQUEUE_MAY; | |
1838 | #endif | |
1839 | } | |
1840 | ||
1841 | static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) | |
1842 | { | |
1843 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1844 | struct task_struct *tsk = current; | |
1845 | struct cfq_queue *cfqq; | |
1846 | ||
1847 | /* | |
1848 | * don't force setup of a queue from here, as a call to may_queue | |
1849 | * does not necessarily imply that a request actually will be queued. | |
1850 | * so just lookup a possibly existing queue, or return 'may queue' | |
1851 | * if that fails | |
1852 | */ | |
3b18152c | 1853 | cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); |
22e2c507 JA |
1854 | if (cfqq) { |
1855 | cfq_init_prio_data(cfqq); | |
1856 | cfq_prio_boost(cfqq); | |
1857 | ||
1858 | return __cfq_may_queue(cfqd, cfqq, tsk, rw); | |
1859 | } | |
1860 | ||
1861 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1862 | } |
1863 | ||
1864 | static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) | |
1865 | { | |
22e2c507 | 1866 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 | 1867 | struct request_list *rl = &q->rq; |
1da177e4 | 1868 | |
22e2c507 JA |
1869 | if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { |
1870 | smp_mb(); | |
1871 | if (waitqueue_active(&rl->wait[READ])) | |
1872 | wake_up(&rl->wait[READ]); | |
1873 | } | |
1874 | ||
1875 | if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { | |
1876 | smp_mb(); | |
1877 | if (waitqueue_active(&rl->wait[WRITE])) | |
1878 | wake_up(&rl->wait[WRITE]); | |
1879 | } | |
1da177e4 LT |
1880 | } |
1881 | ||
1882 | /* | |
1883 | * queue lock held here | |
1884 | */ | |
1885 | static void cfq_put_request(request_queue_t *q, struct request *rq) | |
1886 | { | |
1887 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1888 | struct cfq_rq *crq = RQ_DATA(rq); | |
1889 | ||
1890 | if (crq) { | |
1891 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 | 1892 | const int rw = rq_data_dir(rq); |
1da177e4 | 1893 | |
22e2c507 JA |
1894 | BUG_ON(!cfqq->allocated[rw]); |
1895 | cfqq->allocated[rw]--; | |
1da177e4 | 1896 | |
22e2c507 | 1897 | put_io_context(crq->io_context->ioc); |
1da177e4 LT |
1898 | |
1899 | mempool_free(crq, cfqd->crq_pool); | |
1900 | rq->elevator_private = NULL; | |
1901 | ||
1da177e4 LT |
1902 | cfq_check_waiters(q, cfqq); |
1903 | cfq_put_queue(cfqq); | |
1904 | } | |
1905 | } | |
1906 | ||
1907 | /* | |
22e2c507 | 1908 | * Allocate cfq data structures associated with this request. |
1da177e4 | 1909 | */ |
22e2c507 JA |
1910 | static int |
1911 | cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, | |
8267e268 | 1912 | gfp_t gfp_mask) |
1da177e4 LT |
1913 | { |
1914 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 1915 | struct task_struct *tsk = current; |
1da177e4 LT |
1916 | struct cfq_io_context *cic; |
1917 | const int rw = rq_data_dir(rq); | |
3b18152c | 1918 | pid_t key = cfq_queue_pid(tsk, rw); |
22e2c507 | 1919 | struct cfq_queue *cfqq; |
1da177e4 LT |
1920 | struct cfq_rq *crq; |
1921 | unsigned long flags; | |
12a05732 | 1922 | int is_sync = key != CFQ_KEY_ASYNC; |
1da177e4 LT |
1923 | |
1924 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1925 | ||
3b18152c | 1926 | cic = cfq_get_io_context(cfqd, key, gfp_mask); |
22e2c507 | 1927 | |
1da177e4 LT |
1928 | spin_lock_irqsave(q->queue_lock, flags); |
1929 | ||
22e2c507 JA |
1930 | if (!cic) |
1931 | goto queue_fail; | |
1932 | ||
12a05732 | 1933 | if (!cic->cfqq[is_sync]) { |
3b18152c | 1934 | cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask); |
22e2c507 JA |
1935 | if (!cfqq) |
1936 | goto queue_fail; | |
1da177e4 | 1937 | |
12a05732 | 1938 | cic->cfqq[is_sync] = cfqq; |
22e2c507 | 1939 | } else |
12a05732 | 1940 | cfqq = cic->cfqq[is_sync]; |
1da177e4 LT |
1941 | |
1942 | cfqq->allocated[rw]++; | |
3b18152c | 1943 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 JA |
1944 | cfqd->rq_starved = 0; |
1945 | atomic_inc(&cfqq->ref); | |
1da177e4 LT |
1946 | spin_unlock_irqrestore(q->queue_lock, flags); |
1947 | ||
1da177e4 LT |
1948 | crq = mempool_alloc(cfqd->crq_pool, gfp_mask); |
1949 | if (crq) { | |
1950 | RB_CLEAR(&crq->rb_node); | |
1951 | crq->rb_key = 0; | |
1952 | crq->request = rq; | |
1953 | INIT_HLIST_NODE(&crq->hash); | |
1954 | crq->cfq_queue = cfqq; | |
1955 | crq->io_context = cic; | |
3b18152c | 1956 | |
12a05732 | 1957 | if (is_sync) |
3b18152c JA |
1958 | cfq_mark_crq_is_sync(crq); |
1959 | else | |
1960 | cfq_clear_crq_is_sync(crq); | |
1961 | ||
1da177e4 | 1962 | rq->elevator_private = crq; |
1da177e4 LT |
1963 | return 0; |
1964 | } | |
1965 | ||
1da177e4 LT |
1966 | spin_lock_irqsave(q->queue_lock, flags); |
1967 | cfqq->allocated[rw]--; | |
22e2c507 | 1968 | if (!(cfqq->allocated[0] + cfqq->allocated[1])) |
3b18152c | 1969 | cfq_mark_cfqq_must_alloc(cfqq); |
1da177e4 | 1970 | cfq_put_queue(cfqq); |
22e2c507 JA |
1971 | queue_fail: |
1972 | if (cic) | |
1973 | put_io_context(cic->ioc); | |
1974 | /* | |
1975 | * mark us rq allocation starved. we need to kickstart the process | |
1976 | * ourselves if there are no pending requests that can do it for us. | |
1977 | * that would be an extremely rare OOM situation | |
1978 | */ | |
1979 | cfqd->rq_starved = 1; | |
3b18152c | 1980 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1981 | spin_unlock_irqrestore(q->queue_lock, flags); |
1982 | return 1; | |
1983 | } | |
1984 | ||
22e2c507 JA |
1985 | static void cfq_kick_queue(void *data) |
1986 | { | |
1987 | request_queue_t *q = data; | |
1988 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1989 | unsigned long flags; | |
1990 | ||
1991 | spin_lock_irqsave(q->queue_lock, flags); | |
1992 | ||
1993 | if (cfqd->rq_starved) { | |
1994 | struct request_list *rl = &q->rq; | |
1995 | ||
1996 | /* | |
1997 | * we aren't guaranteed to get a request after this, but we | |
1998 | * have to be opportunistic | |
1999 | */ | |
2000 | smp_mb(); | |
2001 | if (waitqueue_active(&rl->wait[READ])) | |
2002 | wake_up(&rl->wait[READ]); | |
2003 | if (waitqueue_active(&rl->wait[WRITE])) | |
2004 | wake_up(&rl->wait[WRITE]); | |
2005 | } | |
2006 | ||
2007 | blk_remove_plug(q); | |
2008 | q->request_fn(q); | |
2009 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2010 | } | |
2011 | ||
2012 | /* | |
2013 | * Timer running if the active_queue is currently idling inside its time slice | |
2014 | */ | |
2015 | static void cfq_idle_slice_timer(unsigned long data) | |
2016 | { | |
2017 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2018 | struct cfq_queue *cfqq; | |
2019 | unsigned long flags; | |
2020 | ||
2021 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2022 | ||
2023 | if ((cfqq = cfqd->active_queue) != NULL) { | |
2024 | unsigned long now = jiffies; | |
2025 | ||
2026 | /* | |
2027 | * expired | |
2028 | */ | |
2029 | if (time_after(now, cfqq->slice_end)) | |
2030 | goto expire; | |
2031 | ||
2032 | /* | |
2033 | * only expire and reinvoke request handler, if there are | |
2034 | * other queues with pending requests | |
2035 | */ | |
b4878f24 | 2036 | if (!cfqd->busy_queues) { |
22e2c507 JA |
2037 | cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); |
2038 | add_timer(&cfqd->idle_slice_timer); | |
2039 | goto out_cont; | |
2040 | } | |
2041 | ||
2042 | /* | |
2043 | * not expired and it has a request pending, let it dispatch | |
2044 | */ | |
2045 | if (!RB_EMPTY(&cfqq->sort_list)) { | |
3b18152c | 2046 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2047 | goto out_kick; |
2048 | } | |
2049 | } | |
2050 | expire: | |
2051 | cfq_slice_expired(cfqd, 0); | |
2052 | out_kick: | |
3b18152c | 2053 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2054 | out_cont: |
2055 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2056 | } | |
2057 | ||
2058 | /* | |
2059 | * Timer running if an idle class queue is waiting for service | |
2060 | */ | |
2061 | static void cfq_idle_class_timer(unsigned long data) | |
2062 | { | |
2063 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2064 | unsigned long flags, end; | |
2065 | ||
2066 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2067 | ||
2068 | /* | |
2069 | * race with a non-idle queue, reset timer | |
2070 | */ | |
2071 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
2072 | if (!time_after_eq(jiffies, end)) { | |
2073 | cfqd->idle_class_timer.expires = end; | |
2074 | add_timer(&cfqd->idle_class_timer); | |
2075 | } else | |
3b18152c | 2076 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2077 | |
2078 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2079 | } | |
2080 | ||
3b18152c JA |
2081 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2082 | { | |
2083 | del_timer_sync(&cfqd->idle_slice_timer); | |
2084 | del_timer_sync(&cfqd->idle_class_timer); | |
2085 | blk_sync_queue(cfqd->queue); | |
2086 | } | |
22e2c507 | 2087 | |
1da177e4 LT |
2088 | static void cfq_put_cfqd(struct cfq_data *cfqd) |
2089 | { | |
2090 | request_queue_t *q = cfqd->queue; | |
2091 | ||
2092 | if (!atomic_dec_and_test(&cfqd->ref)) | |
2093 | return; | |
2094 | ||
96c51ce9 | 2095 | cfq_shutdown_timer_wq(cfqd); |
4fc20741 | 2096 | blk_put_queue(q); |
96c51ce9 | 2097 | |
1da177e4 LT |
2098 | mempool_destroy(cfqd->crq_pool); |
2099 | kfree(cfqd->crq_hash); | |
2100 | kfree(cfqd->cfq_hash); | |
2101 | kfree(cfqd); | |
2102 | } | |
2103 | ||
2104 | static void cfq_exit_queue(elevator_t *e) | |
2105 | { | |
22e2c507 JA |
2106 | struct cfq_data *cfqd = e->elevator_data; |
2107 | ||
3b18152c | 2108 | cfq_shutdown_timer_wq(cfqd); |
22e2c507 | 2109 | cfq_put_cfqd(cfqd); |
1da177e4 LT |
2110 | } |
2111 | ||
2112 | static int cfq_init_queue(request_queue_t *q, elevator_t *e) | |
2113 | { | |
2114 | struct cfq_data *cfqd; | |
2115 | int i; | |
2116 | ||
2117 | cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); | |
2118 | if (!cfqd) | |
2119 | return -ENOMEM; | |
2120 | ||
2121 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 JA |
2122 | |
2123 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2124 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2125 | ||
2126 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2127 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2128 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
1da177e4 LT |
2129 | INIT_LIST_HEAD(&cfqd->empty_list); |
2130 | ||
2131 | cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); | |
2132 | if (!cfqd->crq_hash) | |
2133 | goto out_crqhash; | |
2134 | ||
2135 | cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); | |
2136 | if (!cfqd->cfq_hash) | |
2137 | goto out_cfqhash; | |
2138 | ||
2139 | cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool); | |
2140 | if (!cfqd->crq_pool) | |
2141 | goto out_crqpool; | |
2142 | ||
2143 | for (i = 0; i < CFQ_MHASH_ENTRIES; i++) | |
2144 | INIT_HLIST_HEAD(&cfqd->crq_hash[i]); | |
2145 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2146 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2147 | ||
2148 | e->elevator_data = cfqd; | |
2149 | ||
2150 | cfqd->queue = q; | |
35797132 | 2151 | atomic_inc(&q->refcnt); |
1da177e4 | 2152 | |
22e2c507 | 2153 | cfqd->max_queued = q->nr_requests / 4; |
1da177e4 | 2154 | q->nr_batching = cfq_queued; |
22e2c507 JA |
2155 | |
2156 | init_timer(&cfqd->idle_slice_timer); | |
2157 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2158 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2159 | ||
2160 | init_timer(&cfqd->idle_class_timer); | |
2161 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2162 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2163 | ||
2164 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); | |
2165 | ||
1da177e4 LT |
2166 | atomic_set(&cfqd->ref, 1); |
2167 | ||
2168 | cfqd->cfq_queued = cfq_queued; | |
2169 | cfqd->cfq_quantum = cfq_quantum; | |
22e2c507 JA |
2170 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2171 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2172 | cfqd->cfq_back_max = cfq_back_max; |
2173 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2174 | cfqd->cfq_slice[0] = cfq_slice_async; |
2175 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2176 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2177 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
2178 | cfqd->cfq_max_depth = cfq_max_depth; | |
3b18152c | 2179 | |
1da177e4 LT |
2180 | return 0; |
2181 | out_crqpool: | |
2182 | kfree(cfqd->cfq_hash); | |
2183 | out_cfqhash: | |
2184 | kfree(cfqd->crq_hash); | |
2185 | out_crqhash: | |
2186 | kfree(cfqd); | |
2187 | return -ENOMEM; | |
2188 | } | |
2189 | ||
2190 | static void cfq_slab_kill(void) | |
2191 | { | |
2192 | if (crq_pool) | |
2193 | kmem_cache_destroy(crq_pool); | |
2194 | if (cfq_pool) | |
2195 | kmem_cache_destroy(cfq_pool); | |
2196 | if (cfq_ioc_pool) | |
2197 | kmem_cache_destroy(cfq_ioc_pool); | |
2198 | } | |
2199 | ||
2200 | static int __init cfq_slab_setup(void) | |
2201 | { | |
2202 | crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, | |
2203 | NULL, NULL); | |
2204 | if (!crq_pool) | |
2205 | goto fail; | |
2206 | ||
2207 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2208 | NULL, NULL); | |
2209 | if (!cfq_pool) | |
2210 | goto fail; | |
2211 | ||
2212 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2213 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2214 | if (!cfq_ioc_pool) | |
2215 | goto fail; | |
2216 | ||
2217 | return 0; | |
2218 | fail: | |
2219 | cfq_slab_kill(); | |
2220 | return -ENOMEM; | |
2221 | } | |
2222 | ||
1da177e4 LT |
2223 | /* |
2224 | * sysfs parts below --> | |
2225 | */ | |
2226 | struct cfq_fs_entry { | |
2227 | struct attribute attr; | |
2228 | ssize_t (*show)(struct cfq_data *, char *); | |
2229 | ssize_t (*store)(struct cfq_data *, const char *, size_t); | |
2230 | }; | |
2231 | ||
2232 | static ssize_t | |
2233 | cfq_var_show(unsigned int var, char *page) | |
2234 | { | |
2235 | return sprintf(page, "%d\n", var); | |
2236 | } | |
2237 | ||
2238 | static ssize_t | |
2239 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2240 | { | |
2241 | char *p = (char *) page; | |
2242 | ||
2243 | *var = simple_strtoul(p, &p, 10); | |
2244 | return count; | |
2245 | } | |
2246 | ||
1da177e4 LT |
2247 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
2248 | static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \ | |
2249 | { \ | |
2250 | unsigned int __data = __VAR; \ | |
2251 | if (__CONV) \ | |
2252 | __data = jiffies_to_msecs(__data); \ | |
2253 | return cfq_var_show(__data, (page)); \ | |
2254 | } | |
2255 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2256 | SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); | |
22e2c507 JA |
2257 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2258 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
1da177e4 LT |
2259 | SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); |
2260 | SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2261 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2262 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2263 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2264 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
2265 | SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0); | |
1da177e4 LT |
2266 | #undef SHOW_FUNCTION |
2267 | ||
2268 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
2269 | static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \ | |
2270 | { \ | |
2271 | unsigned int __data; \ | |
2272 | int ret = cfq_var_store(&__data, (page), count); \ | |
2273 | if (__data < (MIN)) \ | |
2274 | __data = (MIN); \ | |
2275 | else if (__data > (MAX)) \ | |
2276 | __data = (MAX); \ | |
2277 | if (__CONV) \ | |
2278 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2279 | else \ | |
2280 | *(__PTR) = __data; \ | |
2281 | return ret; \ | |
2282 | } | |
2283 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2284 | STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); | |
22e2c507 JA |
2285 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2286 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
1da177e4 LT |
2287 | STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2288 | STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2289 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2290 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2291 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2292 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
2293 | STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0); | |
1da177e4 LT |
2294 | #undef STORE_FUNCTION |
2295 | ||
2296 | static struct cfq_fs_entry cfq_quantum_entry = { | |
2297 | .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR }, | |
2298 | .show = cfq_quantum_show, | |
2299 | .store = cfq_quantum_store, | |
2300 | }; | |
2301 | static struct cfq_fs_entry cfq_queued_entry = { | |
2302 | .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR }, | |
2303 | .show = cfq_queued_show, | |
2304 | .store = cfq_queued_store, | |
2305 | }; | |
22e2c507 | 2306 | static struct cfq_fs_entry cfq_fifo_expire_sync_entry = { |
1da177e4 | 2307 | .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR }, |
22e2c507 JA |
2308 | .show = cfq_fifo_expire_sync_show, |
2309 | .store = cfq_fifo_expire_sync_store, | |
1da177e4 | 2310 | }; |
22e2c507 | 2311 | static struct cfq_fs_entry cfq_fifo_expire_async_entry = { |
1da177e4 | 2312 | .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR }, |
22e2c507 JA |
2313 | .show = cfq_fifo_expire_async_show, |
2314 | .store = cfq_fifo_expire_async_store, | |
1da177e4 LT |
2315 | }; |
2316 | static struct cfq_fs_entry cfq_back_max_entry = { | |
2317 | .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR }, | |
2318 | .show = cfq_back_max_show, | |
2319 | .store = cfq_back_max_store, | |
2320 | }; | |
2321 | static struct cfq_fs_entry cfq_back_penalty_entry = { | |
2322 | .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR }, | |
2323 | .show = cfq_back_penalty_show, | |
2324 | .store = cfq_back_penalty_store, | |
2325 | }; | |
22e2c507 JA |
2326 | static struct cfq_fs_entry cfq_slice_sync_entry = { |
2327 | .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR }, | |
2328 | .show = cfq_slice_sync_show, | |
2329 | .store = cfq_slice_sync_store, | |
1da177e4 | 2330 | }; |
22e2c507 JA |
2331 | static struct cfq_fs_entry cfq_slice_async_entry = { |
2332 | .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR }, | |
2333 | .show = cfq_slice_async_show, | |
2334 | .store = cfq_slice_async_store, | |
2335 | }; | |
2336 | static struct cfq_fs_entry cfq_slice_async_rq_entry = { | |
2337 | .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR }, | |
2338 | .show = cfq_slice_async_rq_show, | |
2339 | .store = cfq_slice_async_rq_store, | |
2340 | }; | |
2341 | static struct cfq_fs_entry cfq_slice_idle_entry = { | |
2342 | .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR }, | |
2343 | .show = cfq_slice_idle_show, | |
2344 | .store = cfq_slice_idle_store, | |
2345 | }; | |
2346 | static struct cfq_fs_entry cfq_max_depth_entry = { | |
2347 | .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR }, | |
2348 | .show = cfq_max_depth_show, | |
2349 | .store = cfq_max_depth_store, | |
1da177e4 | 2350 | }; |
3b18152c | 2351 | |
1da177e4 LT |
2352 | static struct attribute *default_attrs[] = { |
2353 | &cfq_quantum_entry.attr, | |
2354 | &cfq_queued_entry.attr, | |
22e2c507 JA |
2355 | &cfq_fifo_expire_sync_entry.attr, |
2356 | &cfq_fifo_expire_async_entry.attr, | |
1da177e4 LT |
2357 | &cfq_back_max_entry.attr, |
2358 | &cfq_back_penalty_entry.attr, | |
22e2c507 JA |
2359 | &cfq_slice_sync_entry.attr, |
2360 | &cfq_slice_async_entry.attr, | |
2361 | &cfq_slice_async_rq_entry.attr, | |
2362 | &cfq_slice_idle_entry.attr, | |
2363 | &cfq_max_depth_entry.attr, | |
1da177e4 LT |
2364 | NULL, |
2365 | }; | |
2366 | ||
2367 | #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr) | |
2368 | ||
2369 | static ssize_t | |
2370 | cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
2371 | { | |
2372 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
2373 | struct cfq_fs_entry *entry = to_cfq(attr); | |
2374 | ||
2375 | if (!entry->show) | |
6c1852a0 | 2376 | return -EIO; |
1da177e4 LT |
2377 | |
2378 | return entry->show(e->elevator_data, page); | |
2379 | } | |
2380 | ||
2381 | static ssize_t | |
2382 | cfq_attr_store(struct kobject *kobj, struct attribute *attr, | |
2383 | const char *page, size_t length) | |
2384 | { | |
2385 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
2386 | struct cfq_fs_entry *entry = to_cfq(attr); | |
2387 | ||
2388 | if (!entry->store) | |
6c1852a0 | 2389 | return -EIO; |
1da177e4 LT |
2390 | |
2391 | return entry->store(e->elevator_data, page, length); | |
2392 | } | |
2393 | ||
2394 | static struct sysfs_ops cfq_sysfs_ops = { | |
2395 | .show = cfq_attr_show, | |
2396 | .store = cfq_attr_store, | |
2397 | }; | |
2398 | ||
2399 | static struct kobj_type cfq_ktype = { | |
2400 | .sysfs_ops = &cfq_sysfs_ops, | |
2401 | .default_attrs = default_attrs, | |
2402 | }; | |
2403 | ||
2404 | static struct elevator_type iosched_cfq = { | |
2405 | .ops = { | |
2406 | .elevator_merge_fn = cfq_merge, | |
2407 | .elevator_merged_fn = cfq_merged_request, | |
2408 | .elevator_merge_req_fn = cfq_merged_requests, | |
b4878f24 | 2409 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2410 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2411 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2412 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2413 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2414 | .elevator_completed_req_fn = cfq_completed_request, | |
2415 | .elevator_former_req_fn = cfq_former_request, | |
2416 | .elevator_latter_req_fn = cfq_latter_request, | |
2417 | .elevator_set_req_fn = cfq_set_request, | |
2418 | .elevator_put_req_fn = cfq_put_request, | |
2419 | .elevator_may_queue_fn = cfq_may_queue, | |
2420 | .elevator_init_fn = cfq_init_queue, | |
2421 | .elevator_exit_fn = cfq_exit_queue, | |
2422 | }, | |
2423 | .elevator_ktype = &cfq_ktype, | |
2424 | .elevator_name = "cfq", | |
2425 | .elevator_owner = THIS_MODULE, | |
2426 | }; | |
2427 | ||
2428 | static int __init cfq_init(void) | |
2429 | { | |
2430 | int ret; | |
2431 | ||
22e2c507 JA |
2432 | /* |
2433 | * could be 0 on HZ < 1000 setups | |
2434 | */ | |
2435 | if (!cfq_slice_async) | |
2436 | cfq_slice_async = 1; | |
2437 | if (!cfq_slice_idle) | |
2438 | cfq_slice_idle = 1; | |
2439 | ||
1da177e4 LT |
2440 | if (cfq_slab_setup()) |
2441 | return -ENOMEM; | |
2442 | ||
2443 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2444 | if (ret) |
2445 | cfq_slab_kill(); | |
1da177e4 | 2446 | |
1da177e4 LT |
2447 | return ret; |
2448 | } | |
2449 | ||
2450 | static void __exit cfq_exit(void) | |
2451 | { | |
1da177e4 | 2452 | elv_unregister(&iosched_cfq); |
83521d3e | 2453 | cfq_slab_kill(); |
1da177e4 LT |
2454 | } |
2455 | ||
2456 | module_init(cfq_init); | |
2457 | module_exit(cfq_exit); | |
2458 | ||
2459 | MODULE_AUTHOR("Jens Axboe"); | |
2460 | MODULE_LICENSE("GPL"); | |
2461 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |