Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/drivers/block/cfq-iosched.c | |
3 | * | |
4 | * CFQ, or complete fairness queueing, disk scheduler. | |
5 | * | |
6 | * Based on ideas from a previously unfinished io | |
7 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
8 | * | |
9 | * Copyright (C) 2003 Jens Axboe <axboe@suse.de> | |
10 | */ | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/fs.h> | |
13 | #include <linux/blkdev.h> | |
14 | #include <linux/elevator.h> | |
15 | #include <linux/bio.h> | |
16 | #include <linux/config.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/compiler.h> | |
21 | #include <linux/hash.h> | |
22 | #include <linux/rbtree.h> | |
23 | #include <linux/mempool.h> | |
22e2c507 JA |
24 | #include <linux/ioprio.h> |
25 | #include <linux/writeback.h> | |
1da177e4 LT |
26 | |
27 | /* | |
28 | * tunables | |
29 | */ | |
30 | static int cfq_quantum = 4; /* max queue in one round of service */ | |
31 | static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ | |
22e2c507 | 32 | static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
1da177e4 LT |
33 | static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ |
34 | static int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
35 | ||
22e2c507 JA |
36 | static int cfq_slice_sync = HZ / 10; |
37 | static int cfq_slice_async = HZ / 50; | |
38 | static int cfq_slice_async_rq = 2; | |
39 | static int cfq_slice_idle = HZ / 50; | |
40 | ||
41 | #define CFQ_IDLE_GRACE (HZ / 10) | |
42 | #define CFQ_SLICE_SCALE (5) | |
43 | ||
44 | #define CFQ_KEY_ASYNC (0) | |
45 | ||
46 | /* | |
47 | * disable queueing at the driver/hardware level | |
48 | */ | |
49 | static int cfq_max_depth = 1; | |
50 | ||
1da177e4 LT |
51 | /* |
52 | * for the hash of cfqq inside the cfqd | |
53 | */ | |
54 | #define CFQ_QHASH_SHIFT 6 | |
55 | #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) | |
56 | #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) | |
57 | ||
58 | /* | |
59 | * for the hash of crq inside the cfqq | |
60 | */ | |
61 | #define CFQ_MHASH_SHIFT 6 | |
62 | #define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) | |
63 | #define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) | |
64 | #define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) | |
65 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
66 | #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) | |
67 | ||
68 | #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) | |
22e2c507 | 69 | #define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) |
1da177e4 LT |
70 | |
71 | #define RQ_DATA(rq) (rq)->elevator_private | |
72 | ||
73 | /* | |
74 | * rb-tree defines | |
75 | */ | |
76 | #define RB_NONE (2) | |
77 | #define RB_EMPTY(node) ((node)->rb_node == NULL) | |
78 | #define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE | |
79 | #define RB_CLEAR(node) do { \ | |
80 | (node)->rb_parent = NULL; \ | |
81 | RB_CLEAR_COLOR((node)); \ | |
82 | (node)->rb_right = NULL; \ | |
83 | (node)->rb_left = NULL; \ | |
84 | } while (0) | |
85 | #define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) | |
86 | #define ON_RB(node) ((node)->rb_color != RB_NONE) | |
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 | ||
99 | #define cfq_cfqq_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) | |
100 | ||
101 | /* | |
102 | * Per block device queue structure | |
103 | */ | |
1da177e4 | 104 | struct cfq_data { |
22e2c507 JA |
105 | atomic_t ref; |
106 | request_queue_t *queue; | |
107 | ||
108 | /* | |
109 | * rr list of queues with requests and the count of them | |
110 | */ | |
111 | struct list_head rr_list[CFQ_PRIO_LISTS]; | |
112 | struct list_head busy_rr; | |
113 | struct list_head cur_rr; | |
114 | struct list_head idle_rr; | |
115 | unsigned int busy_queues; | |
116 | ||
117 | /* | |
118 | * non-ordered list of empty cfqq's | |
119 | */ | |
1da177e4 LT |
120 | struct list_head empty_list; |
121 | ||
22e2c507 JA |
122 | /* |
123 | * cfqq lookup hash | |
124 | */ | |
1da177e4 | 125 | struct hlist_head *cfq_hash; |
1da177e4 | 126 | |
22e2c507 JA |
127 | /* |
128 | * global crq hash for all queues | |
129 | */ | |
130 | struct hlist_head *crq_hash; | |
1da177e4 LT |
131 | |
132 | unsigned int max_queued; | |
133 | ||
22e2c507 | 134 | mempool_t *crq_pool; |
1da177e4 | 135 | |
22e2c507 | 136 | int rq_in_driver; |
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; | |
170 | unsigned int cfq_max_depth; | |
1da177e4 LT |
171 | }; |
172 | ||
22e2c507 JA |
173 | /* |
174 | * Per process-grouping structure | |
175 | */ | |
1da177e4 LT |
176 | struct cfq_queue { |
177 | /* reference count */ | |
178 | atomic_t ref; | |
179 | /* parent cfq_data */ | |
180 | struct cfq_data *cfqd; | |
22e2c507 | 181 | /* cfqq lookup hash */ |
1da177e4 LT |
182 | struct hlist_node cfq_hash; |
183 | /* hash key */ | |
22e2c507 | 184 | unsigned int key; |
1da177e4 LT |
185 | /* on either rr or empty list of cfqd */ |
186 | struct list_head cfq_list; | |
187 | /* sorted list of pending requests */ | |
188 | struct rb_root sort_list; | |
189 | /* if fifo isn't expired, next request to serve */ | |
190 | struct cfq_rq *next_crq; | |
191 | /* requests queued in sort_list */ | |
192 | int queued[2]; | |
193 | /* currently allocated requests */ | |
194 | int allocated[2]; | |
195 | /* fifo list of requests in sort_list */ | |
22e2c507 | 196 | struct list_head fifo; |
1da177e4 | 197 | |
22e2c507 JA |
198 | unsigned long slice_start; |
199 | unsigned long slice_end; | |
200 | unsigned long slice_left; | |
201 | unsigned long service_last; | |
1da177e4 LT |
202 | |
203 | /* number of requests that have been handed to the driver */ | |
204 | int in_flight; | |
22e2c507 JA |
205 | |
206 | /* io prio of this group */ | |
207 | unsigned short ioprio, org_ioprio; | |
208 | unsigned short ioprio_class, org_ioprio_class; | |
209 | ||
210 | /* whether queue is on rr (or empty) list */ | |
211 | unsigned on_rr : 1; | |
212 | /* idle slice, waiting for new request submission */ | |
213 | unsigned wait_request : 1; | |
214 | /* set when wait_request gets set, reset on first rq alloc */ | |
215 | unsigned must_alloc : 1; | |
216 | /* only gets one must_alloc per slice */ | |
217 | unsigned must_alloc_slice : 1; | |
218 | /* idle slice, request added, now waiting to dispatch it */ | |
219 | unsigned must_dispatch : 1; | |
220 | /* fifo expire per-slice */ | |
221 | unsigned fifo_expire : 1; | |
222 | ||
223 | unsigned idle_window : 1; | |
224 | unsigned prio_changed : 1; | |
1da177e4 LT |
225 | }; |
226 | ||
227 | struct cfq_rq { | |
228 | struct rb_node rb_node; | |
229 | sector_t rb_key; | |
230 | struct request *request; | |
231 | struct hlist_node hash; | |
232 | ||
233 | struct cfq_queue *cfq_queue; | |
234 | struct cfq_io_context *io_context; | |
235 | ||
22e2c507 JA |
236 | unsigned in_flight : 1; |
237 | unsigned accounted : 1; | |
238 | unsigned is_sync : 1; | |
239 | unsigned requeued : 1; | |
1da177e4 LT |
240 | }; |
241 | ||
22e2c507 | 242 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int); |
1da177e4 | 243 | static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *); |
1da177e4 LT |
244 | static void cfq_put_cfqd(struct cfq_data *cfqd); |
245 | ||
22e2c507 | 246 | #define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) |
1da177e4 LT |
247 | |
248 | /* | |
249 | * lots of deadline iosched dupes, can be abstracted later... | |
250 | */ | |
251 | static inline void cfq_del_crq_hash(struct cfq_rq *crq) | |
252 | { | |
253 | hlist_del_init(&crq->hash); | |
254 | } | |
255 | ||
256 | static void cfq_remove_merge_hints(request_queue_t *q, struct cfq_rq *crq) | |
257 | { | |
258 | cfq_del_crq_hash(crq); | |
259 | ||
260 | if (q->last_merge == crq->request) | |
261 | q->last_merge = NULL; | |
1da177e4 LT |
262 | } |
263 | ||
264 | static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) | |
265 | { | |
266 | const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); | |
267 | ||
1da177e4 LT |
268 | hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); |
269 | } | |
270 | ||
271 | static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) | |
272 | { | |
273 | struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; | |
274 | struct hlist_node *entry, *next; | |
275 | ||
276 | hlist_for_each_safe(entry, next, hash_list) { | |
277 | struct cfq_rq *crq = list_entry_hash(entry); | |
278 | struct request *__rq = crq->request; | |
279 | ||
1da177e4 LT |
280 | if (!rq_mergeable(__rq)) { |
281 | cfq_del_crq_hash(crq); | |
282 | continue; | |
283 | } | |
284 | ||
285 | if (rq_hash_key(__rq) == offset) | |
286 | return __rq; | |
287 | } | |
288 | ||
289 | return NULL; | |
290 | } | |
291 | ||
292 | /* | |
293 | * Lifted from AS - choose which of crq1 and crq2 that is best served now. | |
294 | * We choose the request that is closest to the head right now. Distance | |
295 | * behind the head are penalized and only allowed to a certain extent. | |
296 | */ | |
297 | static struct cfq_rq * | |
298 | cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) | |
299 | { | |
300 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
301 | int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */ | |
302 | unsigned long back_max; | |
303 | ||
304 | if (crq1 == NULL || crq1 == crq2) | |
305 | return crq2; | |
306 | if (crq2 == NULL) | |
307 | return crq1; | |
22e2c507 JA |
308 | if (crq1->requeued) |
309 | return crq1; | |
310 | if (crq2->requeued) | |
311 | return crq2; | |
1da177e4 LT |
312 | |
313 | s1 = crq1->request->sector; | |
314 | s2 = crq2->request->sector; | |
315 | ||
316 | last = cfqd->last_sector; | |
317 | ||
1da177e4 LT |
318 | /* |
319 | * by definition, 1KiB is 2 sectors | |
320 | */ | |
321 | back_max = cfqd->cfq_back_max * 2; | |
322 | ||
323 | /* | |
324 | * Strict one way elevator _except_ in the case where we allow | |
325 | * short backward seeks which are biased as twice the cost of a | |
326 | * similar forward seek. | |
327 | */ | |
328 | if (s1 >= last) | |
329 | d1 = s1 - last; | |
330 | else if (s1 + back_max >= last) | |
331 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
332 | else | |
333 | r1_wrap = 1; | |
334 | ||
335 | if (s2 >= last) | |
336 | d2 = s2 - last; | |
337 | else if (s2 + back_max >= last) | |
338 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
339 | else | |
340 | r2_wrap = 1; | |
341 | ||
342 | /* Found required data */ | |
343 | if (!r1_wrap && r2_wrap) | |
344 | return crq1; | |
345 | else if (!r2_wrap && r1_wrap) | |
346 | return crq2; | |
347 | else if (r1_wrap && r2_wrap) { | |
348 | /* both behind the head */ | |
349 | if (s1 <= s2) | |
350 | return crq1; | |
351 | else | |
352 | return crq2; | |
353 | } | |
354 | ||
355 | /* Both requests in front of the head */ | |
356 | if (d1 < d2) | |
357 | return crq1; | |
358 | else if (d2 < d1) | |
359 | return crq2; | |
360 | else { | |
361 | if (s1 >= s2) | |
362 | return crq1; | |
363 | else | |
364 | return crq2; | |
365 | } | |
366 | } | |
367 | ||
368 | /* | |
369 | * would be nice to take fifo expire time into account as well | |
370 | */ | |
371 | static struct cfq_rq * | |
372 | cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
373 | struct cfq_rq *last) | |
374 | { | |
375 | struct cfq_rq *crq_next = NULL, *crq_prev = NULL; | |
376 | struct rb_node *rbnext, *rbprev; | |
377 | ||
3d25f356 | 378 | rbnext = NULL; |
22e2c507 JA |
379 | if (ON_RB(&last->rb_node)) |
380 | rbnext = rb_next(&last->rb_node); | |
3d25f356 | 381 | if (!rbnext) { |
1da177e4 | 382 | rbnext = rb_first(&cfqq->sort_list); |
22e2c507 JA |
383 | if (rbnext == &last->rb_node) |
384 | rbnext = NULL; | |
385 | } | |
1da177e4 LT |
386 | |
387 | rbprev = rb_prev(&last->rb_node); | |
388 | ||
389 | if (rbprev) | |
390 | crq_prev = rb_entry_crq(rbprev); | |
391 | if (rbnext) | |
392 | crq_next = rb_entry_crq(rbnext); | |
393 | ||
394 | return cfq_choose_req(cfqd, crq_next, crq_prev); | |
395 | } | |
396 | ||
397 | static void cfq_update_next_crq(struct cfq_rq *crq) | |
398 | { | |
399 | struct cfq_queue *cfqq = crq->cfq_queue; | |
400 | ||
401 | if (cfqq->next_crq == crq) | |
402 | cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); | |
403 | } | |
404 | ||
22e2c507 | 405 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
1da177e4 | 406 | { |
22e2c507 JA |
407 | struct cfq_data *cfqd = cfqq->cfqd; |
408 | struct list_head *list, *entry; | |
1da177e4 | 409 | |
22e2c507 | 410 | BUG_ON(!cfqq->on_rr); |
1da177e4 | 411 | |
22e2c507 | 412 | list_del(&cfqq->cfq_list); |
1da177e4 | 413 | |
22e2c507 JA |
414 | if (cfq_class_rt(cfqq)) |
415 | list = &cfqd->cur_rr; | |
416 | else if (cfq_class_idle(cfqq)) | |
417 | list = &cfqd->idle_rr; | |
418 | else { | |
419 | /* | |
420 | * if cfqq has requests in flight, don't allow it to be | |
421 | * found in cfq_set_active_queue before it has finished them. | |
422 | * this is done to increase fairness between a process that | |
423 | * has lots of io pending vs one that only generates one | |
424 | * sporadically or synchronously | |
425 | */ | |
426 | if (cfqq->in_flight) | |
427 | list = &cfqd->busy_rr; | |
428 | else | |
429 | list = &cfqd->rr_list[cfqq->ioprio]; | |
1da177e4 LT |
430 | } |
431 | ||
22e2c507 JA |
432 | /* |
433 | * if queue was preempted, just add to front to be fair. busy_rr | |
434 | * isn't sorted. | |
435 | */ | |
436 | if (preempted || list == &cfqd->busy_rr) { | |
437 | list_add(&cfqq->cfq_list, list); | |
1da177e4 | 438 | return; |
22e2c507 | 439 | } |
1da177e4 LT |
440 | |
441 | /* | |
22e2c507 | 442 | * sort by when queue was last serviced |
1da177e4 | 443 | */ |
22e2c507 JA |
444 | entry = list; |
445 | while ((entry = entry->prev) != list) { | |
1da177e4 LT |
446 | struct cfq_queue *__cfqq = list_entry_cfqq(entry); |
447 | ||
22e2c507 JA |
448 | if (!__cfqq->service_last) |
449 | break; | |
450 | if (time_before(__cfqq->service_last, cfqq->service_last)) | |
1da177e4 | 451 | break; |
1da177e4 LT |
452 | } |
453 | ||
454 | list_add(&cfqq->cfq_list, entry); | |
455 | } | |
456 | ||
457 | /* | |
458 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 459 | * the pending list according to last request service |
1da177e4 LT |
460 | */ |
461 | static inline void | |
22e2c507 | 462 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq, int requeue) |
1da177e4 | 463 | { |
22e2c507 | 464 | BUG_ON(cfqq->on_rr); |
1da177e4 LT |
465 | cfqq->on_rr = 1; |
466 | cfqd->busy_queues++; | |
467 | ||
22e2c507 | 468 | cfq_resort_rr_list(cfqq, requeue); |
1da177e4 LT |
469 | } |
470 | ||
471 | static inline void | |
472 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
473 | { | |
22e2c507 | 474 | BUG_ON(!cfqq->on_rr); |
1da177e4 | 475 | cfqq->on_rr = 0; |
22e2c507 | 476 | list_move(&cfqq->cfq_list, &cfqd->empty_list); |
1da177e4 LT |
477 | |
478 | BUG_ON(!cfqd->busy_queues); | |
479 | cfqd->busy_queues--; | |
480 | } | |
481 | ||
482 | /* | |
483 | * rb tree support functions | |
484 | */ | |
485 | static inline void cfq_del_crq_rb(struct cfq_rq *crq) | |
486 | { | |
487 | struct cfq_queue *cfqq = crq->cfq_queue; | |
488 | ||
489 | if (ON_RB(&crq->rb_node)) { | |
490 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 491 | const int sync = crq->is_sync; |
1da177e4 | 492 | |
22e2c507 JA |
493 | BUG_ON(!cfqq->queued[sync]); |
494 | cfqq->queued[sync]--; | |
1da177e4 LT |
495 | |
496 | cfq_update_next_crq(crq); | |
497 | ||
1da177e4 LT |
498 | rb_erase(&crq->rb_node, &cfqq->sort_list); |
499 | RB_CLEAR_COLOR(&crq->rb_node); | |
500 | ||
22e2c507 | 501 | if (cfqq->on_rr && RB_EMPTY(&cfqq->sort_list)) |
1da177e4 LT |
502 | cfq_del_cfqq_rr(cfqd, cfqq); |
503 | } | |
504 | } | |
505 | ||
506 | static struct cfq_rq * | |
507 | __cfq_add_crq_rb(struct cfq_rq *crq) | |
508 | { | |
509 | struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; | |
510 | struct rb_node *parent = NULL; | |
511 | struct cfq_rq *__crq; | |
512 | ||
513 | while (*p) { | |
514 | parent = *p; | |
515 | __crq = rb_entry_crq(parent); | |
516 | ||
517 | if (crq->rb_key < __crq->rb_key) | |
518 | p = &(*p)->rb_left; | |
519 | else if (crq->rb_key > __crq->rb_key) | |
520 | p = &(*p)->rb_right; | |
521 | else | |
522 | return __crq; | |
523 | } | |
524 | ||
525 | rb_link_node(&crq->rb_node, parent, p); | |
526 | return NULL; | |
527 | } | |
528 | ||
529 | static void cfq_add_crq_rb(struct cfq_rq *crq) | |
530 | { | |
531 | struct cfq_queue *cfqq = crq->cfq_queue; | |
532 | struct cfq_data *cfqd = cfqq->cfqd; | |
533 | struct request *rq = crq->request; | |
534 | struct cfq_rq *__alias; | |
535 | ||
536 | crq->rb_key = rq_rb_key(rq); | |
537 | cfqq->queued[crq->is_sync]++; | |
538 | ||
539 | /* | |
540 | * looks a little odd, but the first insert might return an alias. | |
541 | * if that happens, put the alias on the dispatch list | |
542 | */ | |
543 | while ((__alias = __cfq_add_crq_rb(crq)) != NULL) | |
544 | cfq_dispatch_sort(cfqd->queue, __alias); | |
545 | ||
546 | rb_insert_color(&crq->rb_node, &cfqq->sort_list); | |
547 | ||
548 | if (!cfqq->on_rr) | |
22e2c507 | 549 | cfq_add_cfqq_rr(cfqd, cfqq, crq->requeued); |
1da177e4 LT |
550 | |
551 | /* | |
552 | * check if this request is a better next-serve candidate | |
553 | */ | |
554 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
555 | } | |
556 | ||
557 | static inline void | |
558 | cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
559 | { | |
560 | if (ON_RB(&crq->rb_node)) { | |
561 | rb_erase(&crq->rb_node, &cfqq->sort_list); | |
562 | cfqq->queued[crq->is_sync]--; | |
563 | } | |
564 | ||
565 | cfq_add_crq_rb(crq); | |
566 | } | |
567 | ||
22e2c507 JA |
568 | static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector) |
569 | ||
1da177e4 | 570 | { |
22e2c507 | 571 | struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid); |
1da177e4 LT |
572 | struct rb_node *n; |
573 | ||
574 | if (!cfqq) | |
575 | goto out; | |
576 | ||
577 | n = cfqq->sort_list.rb_node; | |
578 | while (n) { | |
579 | struct cfq_rq *crq = rb_entry_crq(n); | |
580 | ||
581 | if (sector < crq->rb_key) | |
582 | n = n->rb_left; | |
583 | else if (sector > crq->rb_key) | |
584 | n = n->rb_right; | |
585 | else | |
586 | return crq->request; | |
587 | } | |
588 | ||
589 | out: | |
590 | return NULL; | |
591 | } | |
592 | ||
593 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) | |
594 | { | |
22e2c507 | 595 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 LT |
596 | struct cfq_rq *crq = RQ_DATA(rq); |
597 | ||
598 | if (crq) { | |
599 | struct cfq_queue *cfqq = crq->cfq_queue; | |
600 | ||
1da177e4 LT |
601 | if (crq->accounted) { |
602 | crq->accounted = 0; | |
22e2c507 JA |
603 | WARN_ON(!cfqd->rq_in_driver); |
604 | cfqd->rq_in_driver--; | |
1da177e4 | 605 | } |
22e2c507 JA |
606 | if (crq->in_flight) { |
607 | crq->in_flight = 0; | |
608 | WARN_ON(!cfqq->in_flight); | |
609 | cfqq->in_flight--; | |
610 | } | |
611 | crq->requeued = 1; | |
1da177e4 LT |
612 | } |
613 | } | |
614 | ||
615 | /* | |
616 | * make sure the service time gets corrected on reissue of this request | |
617 | */ | |
618 | static void cfq_requeue_request(request_queue_t *q, struct request *rq) | |
619 | { | |
620 | cfq_deactivate_request(q, rq); | |
621 | list_add(&rq->queuelist, &q->queue_head); | |
622 | } | |
623 | ||
624 | static void cfq_remove_request(request_queue_t *q, struct request *rq) | |
625 | { | |
626 | struct cfq_rq *crq = RQ_DATA(rq); | |
627 | ||
628 | if (crq) { | |
1da177e4 | 629 | list_del_init(&rq->queuelist); |
22e2c507 JA |
630 | cfq_del_crq_rb(crq); |
631 | cfq_remove_merge_hints(q, crq); | |
1da177e4 | 632 | |
1da177e4 LT |
633 | } |
634 | } | |
635 | ||
636 | static int | |
637 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
638 | { | |
639 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
640 | struct request *__rq; | |
641 | int ret; | |
642 | ||
643 | ret = elv_try_last_merge(q, bio); | |
644 | if (ret != ELEVATOR_NO_MERGE) { | |
645 | __rq = q->last_merge; | |
646 | goto out_insert; | |
647 | } | |
648 | ||
649 | __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); | |
22e2c507 JA |
650 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
651 | ret = ELEVATOR_BACK_MERGE; | |
652 | goto out; | |
1da177e4 LT |
653 | } |
654 | ||
655 | __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio)); | |
22e2c507 JA |
656 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
657 | ret = ELEVATOR_FRONT_MERGE; | |
658 | goto out; | |
1da177e4 LT |
659 | } |
660 | ||
661 | return ELEVATOR_NO_MERGE; | |
662 | out: | |
663 | q->last_merge = __rq; | |
664 | out_insert: | |
665 | *req = __rq; | |
666 | return ret; | |
667 | } | |
668 | ||
669 | static void cfq_merged_request(request_queue_t *q, struct request *req) | |
670 | { | |
671 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
672 | struct cfq_rq *crq = RQ_DATA(req); | |
673 | ||
674 | cfq_del_crq_hash(crq); | |
675 | cfq_add_crq_hash(cfqd, crq); | |
676 | ||
677 | if (ON_RB(&crq->rb_node) && (rq_rb_key(req) != crq->rb_key)) { | |
678 | struct cfq_queue *cfqq = crq->cfq_queue; | |
679 | ||
680 | cfq_update_next_crq(crq); | |
681 | cfq_reposition_crq_rb(cfqq, crq); | |
682 | } | |
683 | ||
684 | q->last_merge = req; | |
685 | } | |
686 | ||
687 | static void | |
688 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
689 | struct request *next) | |
690 | { | |
1da177e4 LT |
691 | cfq_merged_request(q, rq); |
692 | ||
22e2c507 JA |
693 | /* |
694 | * reposition in fifo if next is older than rq | |
695 | */ | |
696 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
697 | time_before(next->start_time, rq->start_time)) | |
698 | list_move(&rq->queuelist, &next->queuelist); | |
699 | ||
700 | cfq_remove_request(q, next); | |
701 | } | |
702 | ||
703 | static inline void | |
704 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
705 | { | |
706 | if (cfqq) { | |
707 | /* | |
708 | * stop potential idle class queues waiting service | |
709 | */ | |
710 | del_timer(&cfqd->idle_class_timer); | |
711 | ||
712 | cfqq->slice_start = jiffies; | |
713 | cfqq->slice_end = 0; | |
714 | cfqq->slice_left = 0; | |
715 | cfqq->must_alloc_slice = 0; | |
716 | cfqq->fifo_expire = 0; | |
717 | } | |
718 | ||
719 | cfqd->active_queue = cfqq; | |
720 | } | |
721 | ||
722 | /* | |
723 | * 0 | |
724 | * 0,1 | |
725 | * 0,1,2 | |
726 | * 0,1,2,3 | |
727 | * 0,1,2,3,4 | |
728 | * 0,1,2,3,4,5 | |
729 | * 0,1,2,3,4,5,6 | |
730 | * 0,1,2,3,4,5,6,7 | |
731 | */ | |
732 | static int cfq_get_next_prio_level(struct cfq_data *cfqd) | |
733 | { | |
734 | int prio, wrap; | |
735 | ||
736 | prio = -1; | |
737 | wrap = 0; | |
738 | do { | |
739 | int p; | |
740 | ||
741 | for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { | |
742 | if (!list_empty(&cfqd->rr_list[p])) { | |
743 | prio = p; | |
744 | break; | |
745 | } | |
746 | } | |
747 | ||
748 | if (prio != -1) | |
749 | break; | |
750 | cfqd->cur_prio = 0; | |
751 | if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
752 | cfqd->cur_end_prio = 0; | |
753 | if (wrap) | |
754 | break; | |
755 | wrap = 1; | |
1da177e4 | 756 | } |
22e2c507 JA |
757 | } while (1); |
758 | ||
759 | if (unlikely(prio == -1)) | |
760 | return -1; | |
761 | ||
762 | BUG_ON(prio >= CFQ_PRIO_LISTS); | |
763 | ||
764 | list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); | |
765 | ||
766 | cfqd->cur_prio = prio + 1; | |
767 | if (cfqd->cur_prio > cfqd->cur_end_prio) { | |
768 | cfqd->cur_end_prio = cfqd->cur_prio; | |
769 | cfqd->cur_prio = 0; | |
770 | } | |
771 | if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { | |
772 | cfqd->cur_prio = 0; | |
773 | cfqd->cur_end_prio = 0; | |
1da177e4 LT |
774 | } |
775 | ||
22e2c507 JA |
776 | return prio; |
777 | } | |
778 | ||
779 | static void cfq_set_active_queue(struct cfq_data *cfqd) | |
780 | { | |
781 | struct cfq_queue *cfqq = NULL; | |
782 | ||
783 | /* | |
784 | * if current list is non-empty, grab first entry. if it is empty, | |
785 | * get next prio level and grab first entry then if any are spliced | |
786 | */ | |
787 | if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) | |
788 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); | |
789 | ||
790 | /* | |
791 | * if we have idle queues and no rt or be queues had pending | |
792 | * requests, either allow immediate service if the grace period | |
793 | * has passed or arm the idle grace timer | |
794 | */ | |
795 | if (!cfqq && !list_empty(&cfqd->idle_rr)) { | |
796 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
797 | ||
798 | if (time_after_eq(jiffies, end)) | |
799 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
800 | else | |
801 | mod_timer(&cfqd->idle_class_timer, end); | |
802 | } | |
803 | ||
804 | __cfq_set_active_queue(cfqd, cfqq); | |
805 | } | |
806 | ||
807 | /* | |
808 | * current cfqq expired its slice (or was too idle), select new one | |
809 | */ | |
810 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) | |
811 | { | |
812 | struct cfq_queue *cfqq = cfqd->active_queue; | |
813 | ||
814 | if (cfqq) { | |
815 | unsigned long now = jiffies; | |
816 | ||
817 | if (cfqq->wait_request) | |
818 | del_timer(&cfqd->idle_slice_timer); | |
819 | ||
820 | if (!preempted && !cfqq->in_flight) | |
821 | cfqq->service_last = now; | |
822 | ||
823 | cfqq->must_dispatch = 0; | |
824 | cfqq->wait_request = 0; | |
825 | ||
826 | /* | |
827 | * store what was left of this slice, if the queue idled out | |
828 | * or was preempted | |
829 | */ | |
830 | if (time_after(now, cfqq->slice_end)) | |
831 | cfqq->slice_left = now - cfqq->slice_end; | |
832 | else | |
833 | cfqq->slice_left = 0; | |
834 | ||
835 | if (cfqq->on_rr) | |
836 | cfq_resort_rr_list(cfqq, preempted); | |
837 | ||
838 | cfqd->active_queue = NULL; | |
839 | ||
840 | if (cfqd->active_cic) { | |
841 | put_io_context(cfqd->active_cic->ioc); | |
842 | cfqd->active_cic = NULL; | |
843 | } | |
844 | } | |
845 | ||
846 | cfqd->dispatch_slice = 0; | |
847 | } | |
848 | ||
849 | static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
850 | ||
851 | { | |
852 | WARN_ON(!RB_EMPTY(&cfqq->sort_list)); | |
853 | WARN_ON(cfqq != cfqd->active_queue); | |
854 | ||
855 | /* | |
856 | * idle is disabled, either manually or by past process history | |
857 | */ | |
858 | if (!cfqd->cfq_slice_idle) | |
859 | return 0; | |
860 | if (!cfqq->idle_window) | |
861 | return 0; | |
862 | /* | |
863 | * task has exited, don't wait | |
864 | */ | |
865 | if (cfqd->active_cic && !cfqd->active_cic->ioc->task) | |
866 | return 0; | |
867 | ||
868 | cfqq->wait_request = 1; | |
869 | cfqq->must_alloc = 1; | |
870 | ||
871 | if (!timer_pending(&cfqd->idle_slice_timer)) { | |
872 | unsigned long slice_left = cfqq->slice_end - 1; | |
873 | ||
874 | cfqd->idle_slice_timer.expires = min(jiffies + cfqd->cfq_slice_idle, slice_left); | |
875 | add_timer(&cfqd->idle_slice_timer); | |
876 | } | |
877 | ||
878 | return 1; | |
1da177e4 LT |
879 | } |
880 | ||
881 | /* | |
882 | * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues, | |
883 | * this function sector sorts the selected request to minimize seeks. we start | |
884 | * at cfqd->last_sector, not 0. | |
885 | */ | |
886 | static void cfq_dispatch_sort(request_queue_t *q, struct cfq_rq *crq) | |
887 | { | |
888 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
889 | struct cfq_queue *cfqq = crq->cfq_queue; | |
890 | struct list_head *head = &q->queue_head, *entry = head; | |
891 | struct request *__rq; | |
892 | sector_t last; | |
893 | ||
1da177e4 LT |
894 | list_del(&crq->request->queuelist); |
895 | ||
896 | last = cfqd->last_sector; | |
22e2c507 JA |
897 | list_for_each_entry_reverse(__rq, head, queuelist) { |
898 | struct cfq_rq *__crq = RQ_DATA(__rq); | |
1da177e4 | 899 | |
22e2c507 JA |
900 | if (blk_barrier_rq(__rq)) |
901 | break; | |
902 | if (!blk_fs_request(__rq)) | |
1da177e4 | 903 | break; |
22e2c507 | 904 | if (__crq->requeued) |
1da177e4 LT |
905 | break; |
906 | ||
22e2c507 | 907 | if (__rq->sector <= crq->request->sector) |
1da177e4 LT |
908 | break; |
909 | if (__rq->sector > last && crq->request->sector < last) { | |
22e2c507 | 910 | last = crq->request->sector + crq->request->nr_sectors; |
1da177e4 LT |
911 | break; |
912 | } | |
22e2c507 | 913 | entry = &__rq->queuelist; |
1da177e4 LT |
914 | } |
915 | ||
916 | cfqd->last_sector = last; | |
22e2c507 JA |
917 | |
918 | cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); | |
919 | ||
920 | cfq_del_crq_rb(crq); | |
921 | cfq_remove_merge_hints(q, crq); | |
922 | ||
1da177e4 | 923 | crq->in_flight = 1; |
22e2c507 | 924 | crq->requeued = 0; |
1da177e4 | 925 | cfqq->in_flight++; |
22e2c507 | 926 | list_add_tail(&crq->request->queuelist, entry); |
1da177e4 LT |
927 | } |
928 | ||
929 | /* | |
930 | * return expired entry, or NULL to just start from scratch in rbtree | |
931 | */ | |
932 | static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) | |
933 | { | |
934 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 935 | struct request *rq; |
1da177e4 LT |
936 | struct cfq_rq *crq; |
937 | ||
22e2c507 | 938 | if (cfqq->fifo_expire) |
1da177e4 LT |
939 | return NULL; |
940 | ||
22e2c507 JA |
941 | if (!list_empty(&cfqq->fifo)) { |
942 | int fifo = cfq_cfqq_sync(cfqq); | |
1da177e4 | 943 | |
22e2c507 JA |
944 | crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); |
945 | rq = crq->request; | |
946 | if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { | |
947 | cfqq->fifo_expire = 1; | |
948 | return crq; | |
949 | } | |
1da177e4 LT |
950 | } |
951 | ||
952 | return NULL; | |
953 | } | |
954 | ||
955 | /* | |
22e2c507 | 956 | * Scale schedule slice based on io priority |
1da177e4 | 957 | */ |
22e2c507 JA |
958 | static inline int |
959 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
960 | { | |
961 | const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; | |
962 | ||
963 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
964 | ||
965 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); | |
966 | } | |
967 | ||
1da177e4 | 968 | static inline void |
22e2c507 | 969 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 970 | { |
22e2c507 JA |
971 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; |
972 | } | |
1da177e4 | 973 | |
22e2c507 JA |
974 | static inline int |
975 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
976 | { | |
977 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 978 | |
22e2c507 | 979 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 980 | |
22e2c507 | 981 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
982 | } |
983 | ||
22e2c507 JA |
984 | /* |
985 | * get next queue for service | |
986 | */ | |
987 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force) | |
1da177e4 | 988 | { |
22e2c507 | 989 | unsigned long now = jiffies; |
1da177e4 | 990 | struct cfq_queue *cfqq; |
1da177e4 | 991 | |
22e2c507 JA |
992 | cfqq = cfqd->active_queue; |
993 | if (!cfqq) | |
994 | goto new_queue; | |
1da177e4 | 995 | |
22e2c507 JA |
996 | /* |
997 | * slice has expired | |
998 | */ | |
999 | if (!cfqq->must_dispatch && time_after(jiffies, cfqq->slice_end)) | |
1000 | goto new_queue; | |
1da177e4 | 1001 | |
22e2c507 JA |
1002 | /* |
1003 | * if queue has requests, dispatch one. if not, check if | |
1004 | * enough slice is left to wait for one | |
1005 | */ | |
1006 | if (!RB_EMPTY(&cfqq->sort_list)) | |
1007 | goto keep_queue; | |
1008 | else if (!force && cfq_cfqq_sync(cfqq) && | |
1009 | time_before(now, cfqq->slice_end)) { | |
1010 | if (cfq_arm_slice_timer(cfqd, cfqq)) | |
1011 | return NULL; | |
1012 | } | |
1013 | ||
1014 | new_queue: | |
1015 | cfq_slice_expired(cfqd, 0); | |
1016 | cfq_set_active_queue(cfqd); | |
1017 | keep_queue: | |
1018 | return cfqd->active_queue; | |
1019 | } | |
1020 | ||
1021 | static int | |
1022 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1023 | int max_dispatch) | |
1024 | { | |
1025 | int dispatched = 0; | |
1026 | ||
1027 | BUG_ON(RB_EMPTY(&cfqq->sort_list)); | |
1028 | ||
1029 | do { | |
1030 | struct cfq_rq *crq; | |
1da177e4 LT |
1031 | |
1032 | /* | |
22e2c507 | 1033 | * follow expired path, else get first next available |
1da177e4 | 1034 | */ |
22e2c507 JA |
1035 | if ((crq = cfq_check_fifo(cfqq)) == NULL) |
1036 | crq = cfqq->next_crq; | |
1037 | ||
1038 | /* | |
1039 | * finally, insert request into driver dispatch list | |
1040 | */ | |
1041 | cfq_dispatch_sort(cfqd->queue, crq); | |
1da177e4 | 1042 | |
22e2c507 JA |
1043 | cfqd->dispatch_slice++; |
1044 | dispatched++; | |
1da177e4 | 1045 | |
22e2c507 JA |
1046 | if (!cfqd->active_cic) { |
1047 | atomic_inc(&crq->io_context->ioc->refcount); | |
1048 | cfqd->active_cic = crq->io_context; | |
1049 | } | |
1da177e4 | 1050 | |
22e2c507 JA |
1051 | if (RB_EMPTY(&cfqq->sort_list)) |
1052 | break; | |
1053 | ||
1054 | } while (dispatched < max_dispatch); | |
1055 | ||
1056 | /* | |
1057 | * if slice end isn't set yet, set it. if at least one request was | |
1058 | * sync, use the sync time slice value | |
1059 | */ | |
1060 | if (!cfqq->slice_end) | |
1061 | cfq_set_prio_slice(cfqd, cfqq); | |
1062 | ||
1063 | /* | |
1064 | * expire an async queue immediately if it has used up its slice. idle | |
1065 | * queue always expire after 1 dispatch round. | |
1066 | */ | |
1067 | if ((!cfq_cfqq_sync(cfqq) && | |
1068 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1069 | cfq_class_idle(cfqq)) | |
1070 | cfq_slice_expired(cfqd, 0); | |
1071 | ||
1072 | return dispatched; | |
1073 | } | |
1074 | ||
1075 | static int | |
1076 | cfq_dispatch_requests(request_queue_t *q, int max_dispatch, int force) | |
1077 | { | |
1078 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1079 | struct cfq_queue *cfqq; | |
1080 | ||
1081 | if (!cfqd->busy_queues) | |
1082 | return 0; | |
1083 | ||
1084 | cfqq = cfq_select_queue(cfqd, force); | |
1085 | if (cfqq) { | |
1086 | cfqq->wait_request = 0; | |
1087 | cfqq->must_dispatch = 0; | |
1088 | del_timer(&cfqd->idle_slice_timer); | |
1089 | ||
1090 | if (cfq_class_idle(cfqq)) | |
1091 | max_dispatch = 1; | |
1da177e4 | 1092 | |
22e2c507 | 1093 | return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1094 | } |
1095 | ||
22e2c507 | 1096 | return 0; |
1da177e4 LT |
1097 | } |
1098 | ||
1099 | static inline void cfq_account_dispatch(struct cfq_rq *crq) | |
1100 | { | |
1101 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1102 | struct cfq_data *cfqd = cfqq->cfqd; | |
1da177e4 | 1103 | |
22e2c507 | 1104 | if (unlikely(!blk_fs_request(crq->request))) |
1da177e4 LT |
1105 | return; |
1106 | ||
1107 | /* | |
1108 | * accounted bit is necessary since some drivers will call | |
1109 | * elv_next_request() many times for the same request (eg ide) | |
1110 | */ | |
1111 | if (crq->accounted) | |
1112 | return; | |
1113 | ||
1da177e4 | 1114 | crq->accounted = 1; |
22e2c507 | 1115 | cfqd->rq_in_driver++; |
1da177e4 LT |
1116 | } |
1117 | ||
1118 | static inline void | |
1119 | cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq) | |
1120 | { | |
1121 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 1122 | unsigned long now; |
1da177e4 LT |
1123 | |
1124 | if (!crq->accounted) | |
1125 | return; | |
1126 | ||
22e2c507 JA |
1127 | now = jiffies; |
1128 | ||
1da177e4 LT |
1129 | WARN_ON(!cfqd->rq_in_driver); |
1130 | cfqd->rq_in_driver--; | |
1131 | ||
22e2c507 JA |
1132 | if (!cfq_class_idle(cfqq)) |
1133 | cfqd->last_end_request = now; | |
1da177e4 | 1134 | |
22e2c507 JA |
1135 | if (!cfqq->in_flight && cfqq->on_rr) { |
1136 | cfqq->service_last = now; | |
1137 | cfq_resort_rr_list(cfqq, 0); | |
1da177e4 | 1138 | } |
22e2c507 JA |
1139 | |
1140 | if (crq->is_sync) | |
1141 | crq->io_context->last_end_request = now; | |
1da177e4 LT |
1142 | } |
1143 | ||
1144 | static struct request *cfq_next_request(request_queue_t *q) | |
1145 | { | |
1146 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1147 | struct request *rq; | |
1148 | ||
1149 | if (!list_empty(&q->queue_head)) { | |
1150 | struct cfq_rq *crq; | |
1151 | dispatch: | |
1152 | rq = list_entry_rq(q->queue_head.next); | |
1153 | ||
22e2c507 JA |
1154 | crq = RQ_DATA(rq); |
1155 | if (crq) { | |
1156 | /* | |
1157 | * if idle window is disabled, allow queue buildup | |
1158 | */ | |
1159 | if (!crq->in_flight && !crq->cfq_queue->idle_window && | |
1160 | cfqd->rq_in_driver >= cfqd->cfq_max_depth) | |
1161 | return NULL; | |
1162 | ||
1da177e4 LT |
1163 | cfq_remove_merge_hints(q, crq); |
1164 | cfq_account_dispatch(crq); | |
1165 | } | |
1166 | ||
1167 | return rq; | |
1168 | } | |
1169 | ||
22e2c507 | 1170 | if (cfq_dispatch_requests(q, cfqd->cfq_quantum, 0)) |
1da177e4 LT |
1171 | goto dispatch; |
1172 | ||
1173 | return NULL; | |
1174 | } | |
1175 | ||
1176 | /* | |
1177 | * task holds one reference to the queue, dropped when task exits. each crq | |
1178 | * in-flight on this queue also holds a reference, dropped when crq is freed. | |
1179 | * | |
1180 | * queue lock must be held here. | |
1181 | */ | |
1182 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1183 | { | |
22e2c507 JA |
1184 | struct cfq_data *cfqd = cfqq->cfqd; |
1185 | ||
1186 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1187 | |
1188 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1189 | return; | |
1190 | ||
1191 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1192 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
1da177e4 LT |
1193 | BUG_ON(cfqq->on_rr); |
1194 | ||
22e2c507 JA |
1195 | if (unlikely(cfqd->active_queue == cfqq)) { |
1196 | cfq_slice_expired(cfqd, 0); | |
1197 | kblockd_schedule_work(&cfqd->unplug_work); | |
1198 | } | |
1199 | ||
1da177e4 LT |
1200 | cfq_put_cfqd(cfqq->cfqd); |
1201 | ||
1202 | /* | |
1203 | * it's on the empty list and still hashed | |
1204 | */ | |
1205 | list_del(&cfqq->cfq_list); | |
1206 | hlist_del(&cfqq->cfq_hash); | |
1207 | kmem_cache_free(cfq_pool, cfqq); | |
1208 | } | |
1209 | ||
1210 | static inline struct cfq_queue * | |
22e2c507 | 1211 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, const int hashval) |
1da177e4 LT |
1212 | { |
1213 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
1214 | struct hlist_node *entry, *next; | |
1215 | ||
1216 | hlist_for_each_safe(entry, next, hash_list) { | |
1217 | struct cfq_queue *__cfqq = list_entry_qhash(entry); | |
1218 | ||
1219 | if (__cfqq->key == key) | |
1220 | return __cfqq; | |
1221 | } | |
1222 | ||
1223 | return NULL; | |
1224 | } | |
1225 | ||
1226 | static struct cfq_queue * | |
22e2c507 | 1227 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key) |
1da177e4 LT |
1228 | { |
1229 | return __cfq_find_cfq_hash(cfqd, key, hash_long(key, CFQ_QHASH_SHIFT)); | |
1230 | } | |
1231 | ||
22e2c507 | 1232 | static void cfq_free_io_context(struct cfq_io_context *cic) |
1da177e4 | 1233 | { |
22e2c507 JA |
1234 | struct cfq_io_context *__cic; |
1235 | struct list_head *entry, *next; | |
1da177e4 | 1236 | |
22e2c507 JA |
1237 | list_for_each_safe(entry, next, &cic->list) { |
1238 | __cic = list_entry(entry, struct cfq_io_context, list); | |
1239 | kmem_cache_free(cfq_ioc_pool, __cic); | |
1da177e4 LT |
1240 | } |
1241 | ||
22e2c507 | 1242 | kmem_cache_free(cfq_ioc_pool, cic); |
1da177e4 LT |
1243 | } |
1244 | ||
22e2c507 JA |
1245 | /* |
1246 | * Called with interrupts disabled | |
1247 | */ | |
1248 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1da177e4 | 1249 | { |
22e2c507 JA |
1250 | struct cfq_data *cfqd = cic->cfqq->cfqd; |
1251 | request_queue_t *q = cfqd->queue; | |
1252 | ||
1253 | WARN_ON(!irqs_disabled()); | |
1254 | ||
1255 | spin_lock(q->queue_lock); | |
1256 | ||
1257 | if (unlikely(cic->cfqq == cfqd->active_queue)) { | |
1258 | cfq_slice_expired(cfqd, 0); | |
1259 | kblockd_schedule_work(&cfqd->unplug_work); | |
1260 | } | |
1261 | ||
1262 | cfq_put_queue(cic->cfqq); | |
1263 | cic->cfqq = NULL; | |
1264 | spin_unlock(q->queue_lock); | |
1da177e4 LT |
1265 | } |
1266 | ||
1267 | /* | |
22e2c507 JA |
1268 | * Another task may update the task cic list, if it is doing a queue lookup |
1269 | * on its behalf. cfq_cic_lock excludes such concurrent updates | |
1da177e4 LT |
1270 | */ |
1271 | static void cfq_exit_io_context(struct cfq_io_context *cic) | |
1272 | { | |
22e2c507 JA |
1273 | struct cfq_io_context *__cic; |
1274 | struct list_head *entry; | |
1da177e4 LT |
1275 | unsigned long flags; |
1276 | ||
22e2c507 JA |
1277 | local_irq_save(flags); |
1278 | ||
1da177e4 LT |
1279 | /* |
1280 | * put the reference this task is holding to the various queues | |
1281 | */ | |
22e2c507 | 1282 | list_for_each(entry, &cic->list) { |
1da177e4 | 1283 | __cic = list_entry(entry, struct cfq_io_context, list); |
22e2c507 | 1284 | cfq_exit_single_io_context(__cic); |
1da177e4 LT |
1285 | } |
1286 | ||
22e2c507 JA |
1287 | cfq_exit_single_io_context(cic); |
1288 | local_irq_restore(flags); | |
1da177e4 LT |
1289 | } |
1290 | ||
22e2c507 JA |
1291 | static struct cfq_io_context * |
1292 | cfq_alloc_io_context(struct cfq_data *cfqd, int gfp_mask) | |
1da177e4 | 1293 | { |
22e2c507 | 1294 | struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); |
1da177e4 LT |
1295 | |
1296 | if (cic) { | |
1da177e4 LT |
1297 | INIT_LIST_HEAD(&cic->list); |
1298 | cic->cfqq = NULL; | |
22e2c507 JA |
1299 | cic->key = NULL; |
1300 | cic->last_end_request = jiffies; | |
1301 | cic->ttime_total = 0; | |
1302 | cic->ttime_samples = 0; | |
1303 | cic->ttime_mean = 0; | |
1304 | cic->dtor = cfq_free_io_context; | |
1305 | cic->exit = cfq_exit_io_context; | |
1da177e4 LT |
1306 | } |
1307 | ||
1308 | return cic; | |
1309 | } | |
1310 | ||
22e2c507 JA |
1311 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1312 | { | |
1313 | struct task_struct *tsk = current; | |
1314 | int ioprio_class; | |
1315 | ||
1316 | if (!cfqq->prio_changed) | |
1317 | return; | |
1318 | ||
1319 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1320 | switch (ioprio_class) { | |
1321 | default: | |
1322 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1323 | case IOPRIO_CLASS_NONE: | |
1324 | /* | |
1325 | * no prio set, place us in the middle of the BE classes | |
1326 | */ | |
1327 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1328 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1329 | break; | |
1330 | case IOPRIO_CLASS_RT: | |
1331 | cfqq->ioprio = task_ioprio(tsk); | |
1332 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1333 | break; | |
1334 | case IOPRIO_CLASS_BE: | |
1335 | cfqq->ioprio = task_ioprio(tsk); | |
1336 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1337 | break; | |
1338 | case IOPRIO_CLASS_IDLE: | |
1339 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1340 | cfqq->ioprio = 7; | |
1341 | cfqq->idle_window = 0; | |
1342 | break; | |
1343 | } | |
1344 | ||
1345 | /* | |
1346 | * keep track of original prio settings in case we have to temporarily | |
1347 | * elevate the priority of this queue | |
1348 | */ | |
1349 | cfqq->org_ioprio = cfqq->ioprio; | |
1350 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
1351 | ||
1352 | if (cfqq->on_rr) | |
1353 | cfq_resort_rr_list(cfqq, 0); | |
1354 | ||
1355 | cfqq->prio_changed = 0; | |
1356 | } | |
1357 | ||
1358 | static inline void changed_ioprio(struct cfq_queue *cfqq) | |
1359 | { | |
1360 | if (cfqq) { | |
1361 | struct cfq_data *cfqd = cfqq->cfqd; | |
1362 | ||
1363 | spin_lock(cfqd->queue->queue_lock); | |
1364 | cfqq->prio_changed = 1; | |
1365 | cfq_init_prio_data(cfqq); | |
1366 | spin_unlock(cfqd->queue->queue_lock); | |
1367 | } | |
1368 | } | |
1369 | ||
1370 | /* | |
1371 | * callback from sys_ioprio_set, irqs are disabled | |
1372 | */ | |
1373 | static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) | |
1374 | { | |
1375 | struct cfq_io_context *cic = ioc->cic; | |
1376 | ||
1377 | changed_ioprio(cic->cfqq); | |
1378 | ||
1379 | list_for_each_entry(cic, &cic->list, list) | |
1380 | changed_ioprio(cic->cfqq); | |
1381 | ||
1382 | return 0; | |
1383 | } | |
1384 | ||
1385 | static struct cfq_queue * | |
1386 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, int gfp_mask) | |
1387 | { | |
1388 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1389 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
1390 | ||
1391 | retry: | |
1392 | cfqq = __cfq_find_cfq_hash(cfqd, key, hashval); | |
1393 | ||
1394 | if (!cfqq) { | |
1395 | if (new_cfqq) { | |
1396 | cfqq = new_cfqq; | |
1397 | new_cfqq = NULL; | |
1398 | } else if (gfp_mask & __GFP_WAIT) { | |
1399 | spin_unlock_irq(cfqd->queue->queue_lock); | |
1400 | new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1401 | spin_lock_irq(cfqd->queue->queue_lock); | |
1402 | goto retry; | |
1403 | } else { | |
1404 | cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); | |
1405 | if (!cfqq) | |
1406 | goto out; | |
1407 | } | |
1408 | ||
1409 | memset(cfqq, 0, sizeof(*cfqq)); | |
1410 | ||
1411 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1412 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
1413 | RB_CLEAR_ROOT(&cfqq->sort_list); | |
1414 | INIT_LIST_HEAD(&cfqq->fifo); | |
1415 | ||
1416 | cfqq->key = key; | |
1417 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1418 | atomic_set(&cfqq->ref, 0); | |
1419 | cfqq->cfqd = cfqd; | |
1420 | atomic_inc(&cfqd->ref); | |
1421 | cfqq->service_last = 0; | |
1422 | /* | |
1423 | * set ->slice_left to allow preemption for a new process | |
1424 | */ | |
1425 | cfqq->slice_left = 2 * cfqd->cfq_slice_idle; | |
1426 | cfqq->idle_window = 1; | |
1427 | cfqq->ioprio = -1; | |
1428 | cfqq->ioprio_class = -1; | |
1429 | cfqq->prio_changed = 1; | |
1430 | } | |
1431 | ||
1432 | if (new_cfqq) | |
1433 | kmem_cache_free(cfq_pool, new_cfqq); | |
1434 | ||
1435 | atomic_inc(&cfqq->ref); | |
1436 | out: | |
1437 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1438 | return cfqq; | |
1439 | } | |
1440 | ||
1da177e4 LT |
1441 | /* |
1442 | * Setup general io context and cfq io context. There can be several cfq | |
1443 | * io contexts per general io context, if this process is doing io to more | |
1444 | * than one device managed by cfq. Note that caller is holding a reference to | |
1445 | * cfqq, so we don't need to worry about it disappearing | |
1446 | */ | |
1447 | static struct cfq_io_context * | |
22e2c507 | 1448 | cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, int gfp_mask) |
1da177e4 | 1449 | { |
22e2c507 | 1450 | struct io_context *ioc = NULL; |
1da177e4 | 1451 | struct cfq_io_context *cic; |
1da177e4 | 1452 | |
22e2c507 | 1453 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1454 | |
22e2c507 | 1455 | ioc = get_io_context(gfp_mask); |
1da177e4 LT |
1456 | if (!ioc) |
1457 | return NULL; | |
1458 | ||
1459 | if ((cic = ioc->cic) == NULL) { | |
22e2c507 | 1460 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1da177e4 LT |
1461 | |
1462 | if (cic == NULL) | |
1463 | goto err; | |
1464 | ||
22e2c507 JA |
1465 | /* |
1466 | * manually increment generic io_context usage count, it | |
1467 | * cannot go away since we are already holding one ref to it | |
1468 | */ | |
1da177e4 | 1469 | ioc->cic = cic; |
22e2c507 | 1470 | ioc->set_ioprio = cfq_ioc_set_ioprio; |
1da177e4 | 1471 | cic->ioc = ioc; |
22e2c507 JA |
1472 | cic->key = cfqd; |
1473 | atomic_inc(&cfqd->ref); | |
1da177e4 LT |
1474 | } else { |
1475 | struct cfq_io_context *__cic; | |
1da177e4 LT |
1476 | |
1477 | /* | |
22e2c507 | 1478 | * the first cic on the list is actually the head itself |
1da177e4 | 1479 | */ |
22e2c507 | 1480 | if (cic->key == cfqd) |
1da177e4 LT |
1481 | goto out; |
1482 | ||
1483 | /* | |
1484 | * cic exists, check if we already are there. linear search | |
1485 | * should be ok here, the list will usually not be more than | |
1486 | * 1 or a few entries long | |
1487 | */ | |
1da177e4 LT |
1488 | list_for_each_entry(__cic, &cic->list, list) { |
1489 | /* | |
1490 | * this process is already holding a reference to | |
1491 | * this queue, so no need to get one more | |
1492 | */ | |
22e2c507 | 1493 | if (__cic->key == cfqd) { |
1da177e4 | 1494 | cic = __cic; |
1da177e4 LT |
1495 | goto out; |
1496 | } | |
1497 | } | |
1da177e4 LT |
1498 | |
1499 | /* | |
1500 | * nope, process doesn't have a cic assoicated with this | |
1501 | * cfqq yet. get a new one and add to list | |
1502 | */ | |
22e2c507 | 1503 | __cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1da177e4 LT |
1504 | if (__cic == NULL) |
1505 | goto err; | |
1506 | ||
1507 | __cic->ioc = ioc; | |
22e2c507 JA |
1508 | __cic->key = cfqd; |
1509 | atomic_inc(&cfqd->ref); | |
1da177e4 | 1510 | list_add(&__cic->list, &cic->list); |
1da177e4 | 1511 | cic = __cic; |
1da177e4 LT |
1512 | } |
1513 | ||
1514 | out: | |
1da177e4 LT |
1515 | return cic; |
1516 | err: | |
1517 | put_io_context(ioc); | |
1518 | return NULL; | |
1519 | } | |
1520 | ||
22e2c507 JA |
1521 | static void |
1522 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1523 | { |
22e2c507 | 1524 | unsigned long elapsed, ttime; |
1da177e4 | 1525 | |
22e2c507 JA |
1526 | /* |
1527 | * if this context already has stuff queued, thinktime is from | |
1528 | * last queue not last end | |
1529 | */ | |
1530 | #if 0 | |
1531 | if (time_after(cic->last_end_request, cic->last_queue)) | |
1532 | elapsed = jiffies - cic->last_end_request; | |
1533 | else | |
1534 | elapsed = jiffies - cic->last_queue; | |
1535 | #else | |
1536 | elapsed = jiffies - cic->last_end_request; | |
1537 | #endif | |
1da177e4 | 1538 | |
22e2c507 | 1539 | ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
db3b5848 | 1540 | |
22e2c507 JA |
1541 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1542 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1543 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1544 | } | |
1da177e4 | 1545 | |
22e2c507 | 1546 | #define sample_valid(samples) ((samples) > 80) |
1da177e4 | 1547 | |
22e2c507 JA |
1548 | /* |
1549 | * Disable idle window if the process thinks too long or seeks so much that | |
1550 | * it doesn't matter | |
1551 | */ | |
1552 | static void | |
1553 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1554 | struct cfq_io_context *cic) | |
1555 | { | |
1556 | int enable_idle = cfqq->idle_window; | |
1da177e4 | 1557 | |
22e2c507 JA |
1558 | if (!cic->ioc->task || !cfqd->cfq_slice_idle) |
1559 | enable_idle = 0; | |
1560 | else if (sample_valid(cic->ttime_samples)) { | |
1561 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1562 | enable_idle = 0; | |
1563 | else | |
1564 | enable_idle = 1; | |
1da177e4 LT |
1565 | } |
1566 | ||
22e2c507 JA |
1567 | cfqq->idle_window = enable_idle; |
1568 | } | |
1da177e4 | 1569 | |
22e2c507 JA |
1570 | |
1571 | /* | |
1572 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1573 | * no or if we aren't sure, a 1 will cause a preempt. | |
1574 | */ | |
1575 | static int | |
1576 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
1577 | struct cfq_rq *crq) | |
1578 | { | |
1579 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1580 | ||
1581 | if (cfq_class_idle(new_cfqq)) | |
1582 | return 0; | |
1583 | ||
1584 | if (!cfqq) | |
1585 | return 1; | |
1586 | ||
1587 | if (cfq_class_idle(cfqq)) | |
1588 | return 1; | |
1589 | if (!new_cfqq->wait_request) | |
1590 | return 0; | |
1591 | /* | |
1592 | * if it doesn't have slice left, forget it | |
1593 | */ | |
1594 | if (new_cfqq->slice_left < cfqd->cfq_slice_idle) | |
1595 | return 0; | |
1596 | if (crq->is_sync && !cfq_cfqq_sync(cfqq)) | |
1597 | return 1; | |
1598 | ||
1599 | return 0; | |
1600 | } | |
1601 | ||
1602 | /* | |
1603 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1604 | * let it have half of its nominal slice. | |
1605 | */ | |
1606 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1607 | { | |
1608 | struct cfq_queue *__cfqq, *next; | |
1609 | ||
1610 | list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) | |
1611 | cfq_resort_rr_list(__cfqq, 1); | |
1612 | ||
1613 | if (!cfqq->slice_left) | |
1614 | cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; | |
1615 | ||
1616 | cfqq->slice_end = cfqq->slice_left + jiffies; | |
1617 | cfq_slice_expired(cfqd, 1); | |
1618 | __cfq_set_active_queue(cfqd, cfqq); | |
1619 | } | |
1620 | ||
1621 | /* | |
1622 | * should really be a ll_rw_blk.c helper | |
1623 | */ | |
1624 | static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1625 | { | |
1626 | request_queue_t *q = cfqd->queue; | |
1627 | ||
1628 | if (!blk_queue_plugged(q)) | |
1629 | q->request_fn(q); | |
1630 | else | |
1631 | __generic_unplug_device(q); | |
1632 | } | |
1633 | ||
1634 | /* | |
1635 | * Called when a new fs request (crq) is added (to cfqq). Check if there's | |
1636 | * something we should do about it | |
1637 | */ | |
1638 | static void | |
1639 | cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1640 | struct cfq_rq *crq) | |
1641 | { | |
1642 | const int sync = crq->is_sync; | |
1643 | ||
1644 | cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); | |
1645 | ||
1646 | if (sync) { | |
1647 | struct cfq_io_context *cic = crq->io_context; | |
1648 | ||
1649 | cfq_update_io_thinktime(cfqd, cic); | |
1650 | cfq_update_idle_window(cfqd, cfqq, cic); | |
1651 | ||
1652 | cic->last_queue = jiffies; | |
1653 | } | |
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 | */ | |
1661 | if (cfqq->wait_request) { | |
1662 | cfqq->must_dispatch = 1; | |
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); | |
1673 | cfqq->must_dispatch = 1; | |
1674 | cfq_start_queueing(cfqd, cfqq); | |
1675 | } | |
1da177e4 LT |
1676 | } |
1677 | ||
22e2c507 | 1678 | static void cfq_enqueue(struct cfq_data *cfqd, struct request *rq) |
1da177e4 | 1679 | { |
22e2c507 JA |
1680 | struct cfq_rq *crq = RQ_DATA(rq); |
1681 | struct cfq_queue *cfqq = crq->cfq_queue; | |
1682 | ||
1683 | cfq_init_prio_data(cfqq); | |
1da177e4 LT |
1684 | |
1685 | cfq_add_crq_rb(crq); | |
1da177e4 | 1686 | |
22e2c507 JA |
1687 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1688 | ||
1689 | if (rq_mergeable(rq)) { | |
1690 | cfq_add_crq_hash(cfqd, crq); | |
1691 | ||
1692 | if (!cfqd->queue->last_merge) | |
1693 | cfqd->queue->last_merge = rq; | |
1694 | } | |
1695 | ||
1696 | cfq_crq_enqueued(cfqd, cfqq, crq); | |
1da177e4 LT |
1697 | } |
1698 | ||
1699 | static void | |
1700 | cfq_insert_request(request_queue_t *q, struct request *rq, int where) | |
1701 | { | |
1702 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1da177e4 LT |
1703 | |
1704 | switch (where) { | |
1705 | case ELEVATOR_INSERT_BACK: | |
22e2c507 | 1706 | while (cfq_dispatch_requests(q, INT_MAX, 1)) |
1da177e4 LT |
1707 | ; |
1708 | list_add_tail(&rq->queuelist, &q->queue_head); | |
22e2c507 JA |
1709 | /* |
1710 | * If we were idling with pending requests on | |
1711 | * inactive cfqqs, force dispatching will | |
1712 | * remove the idle timer and the queue won't | |
1713 | * be kicked by __make_request() afterward. | |
1714 | * Kick it here. | |
1715 | */ | |
1716 | kblockd_schedule_work(&cfqd->unplug_work); | |
1da177e4 LT |
1717 | break; |
1718 | case ELEVATOR_INSERT_FRONT: | |
1719 | list_add(&rq->queuelist, &q->queue_head); | |
1720 | break; | |
1721 | case ELEVATOR_INSERT_SORT: | |
1722 | BUG_ON(!blk_fs_request(rq)); | |
22e2c507 | 1723 | cfq_enqueue(cfqd, rq); |
1da177e4 LT |
1724 | break; |
1725 | default: | |
1726 | printk("%s: bad insert point %d\n", __FUNCTION__,where); | |
1727 | return; | |
1728 | } | |
22e2c507 | 1729 | } |
1da177e4 | 1730 | |
22e2c507 JA |
1731 | static inline int cfq_pending_requests(struct cfq_data *cfqd) |
1732 | { | |
1733 | return !list_empty(&cfqd->queue->queue_head) || cfqd->busy_queues; | |
1da177e4 LT |
1734 | } |
1735 | ||
1736 | static int cfq_queue_empty(request_queue_t *q) | |
1737 | { | |
1738 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1739 | ||
22e2c507 | 1740 | return !cfq_pending_requests(cfqd); |
1da177e4 LT |
1741 | } |
1742 | ||
1743 | static void cfq_completed_request(request_queue_t *q, struct request *rq) | |
1744 | { | |
1745 | struct cfq_rq *crq = RQ_DATA(rq); | |
1746 | struct cfq_queue *cfqq; | |
1747 | ||
1748 | if (unlikely(!blk_fs_request(rq))) | |
1749 | return; | |
1750 | ||
1751 | cfqq = crq->cfq_queue; | |
1752 | ||
1753 | if (crq->in_flight) { | |
1754 | WARN_ON(!cfqq->in_flight); | |
1755 | cfqq->in_flight--; | |
1756 | } | |
1757 | ||
1758 | cfq_account_completion(cfqq, crq); | |
1759 | } | |
1760 | ||
1761 | static struct request * | |
1762 | cfq_former_request(request_queue_t *q, struct request *rq) | |
1763 | { | |
1764 | struct cfq_rq *crq = RQ_DATA(rq); | |
1765 | struct rb_node *rbprev = rb_prev(&crq->rb_node); | |
1766 | ||
1767 | if (rbprev) | |
1768 | return rb_entry_crq(rbprev)->request; | |
1769 | ||
1770 | return NULL; | |
1771 | } | |
1772 | ||
1773 | static struct request * | |
1774 | cfq_latter_request(request_queue_t *q, struct request *rq) | |
1775 | { | |
1776 | struct cfq_rq *crq = RQ_DATA(rq); | |
1777 | struct rb_node *rbnext = rb_next(&crq->rb_node); | |
1778 | ||
1779 | if (rbnext) | |
1780 | return rb_entry_crq(rbnext)->request; | |
1781 | ||
1782 | return NULL; | |
1783 | } | |
1784 | ||
22e2c507 JA |
1785 | /* |
1786 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1787 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1788 | */ | |
1789 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1790 | { |
22e2c507 JA |
1791 | const int ioprio_class = cfqq->ioprio_class; |
1792 | const int ioprio = cfqq->ioprio; | |
1da177e4 | 1793 | |
22e2c507 JA |
1794 | if (has_fs_excl()) { |
1795 | /* | |
1796 | * boost idle prio on transactions that would lock out other | |
1797 | * users of the filesystem | |
1798 | */ | |
1799 | if (cfq_class_idle(cfqq)) | |
1800 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1801 | if (cfqq->ioprio > IOPRIO_NORM) | |
1802 | cfqq->ioprio = IOPRIO_NORM; | |
1803 | } else { | |
1804 | /* | |
1805 | * check if we need to unboost the queue | |
1806 | */ | |
1807 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1808 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1809 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1810 | cfqq->ioprio = cfqq->org_ioprio; | |
1811 | } | |
1da177e4 | 1812 | |
22e2c507 JA |
1813 | /* |
1814 | * refile between round-robin lists if we moved the priority class | |
1815 | */ | |
1816 | if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && | |
1817 | cfqq->on_rr) | |
1818 | cfq_resort_rr_list(cfqq, 0); | |
1819 | } | |
1da177e4 | 1820 | |
22e2c507 JA |
1821 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) |
1822 | { | |
1823 | if (rw == READ || process_sync(task)) | |
1824 | return task->pid; | |
1da177e4 | 1825 | |
22e2c507 JA |
1826 | return CFQ_KEY_ASYNC; |
1827 | } | |
1da177e4 | 1828 | |
22e2c507 JA |
1829 | static inline int |
1830 | __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1831 | struct task_struct *task, int rw) | |
1832 | { | |
1833 | if (cfqq->wait_request && cfqq->must_alloc) | |
1834 | return ELV_MQUEUE_MUST; | |
1da177e4 | 1835 | |
22e2c507 JA |
1836 | return ELV_MQUEUE_MAY; |
1837 | #if 0 | |
1838 | if (!cfqq || task->flags & PF_MEMALLOC) | |
1839 | return ELV_MQUEUE_MAY; | |
1840 | if (!cfqq->allocated[rw] || cfqq->must_alloc) { | |
1841 | if (cfqq->wait_request) | |
1842 | return ELV_MQUEUE_MUST; | |
1da177e4 | 1843 | |
22e2c507 JA |
1844 | /* |
1845 | * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we | |
1846 | * can quickly flood the queue with writes from a single task | |
1847 | */ | |
1848 | if (rw == READ || !cfqq->must_alloc_slice) { | |
1849 | cfqq->must_alloc_slice = 1; | |
1850 | return ELV_MQUEUE_MUST; | |
1da177e4 | 1851 | } |
22e2c507 JA |
1852 | |
1853 | return ELV_MQUEUE_MAY; | |
1da177e4 | 1854 | } |
22e2c507 JA |
1855 | if (cfq_class_idle(cfqq)) |
1856 | return ELV_MQUEUE_NO; | |
1857 | if (cfqq->allocated[rw] >= cfqd->max_queued) { | |
1858 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
1859 | int ret = ELV_MQUEUE_NO; | |
1da177e4 | 1860 | |
22e2c507 JA |
1861 | if (ioc && ioc->nr_batch_requests) |
1862 | ret = ELV_MQUEUE_MAY; | |
1863 | ||
1864 | put_io_context(ioc); | |
1865 | return ret; | |
1866 | } | |
1867 | ||
1868 | return ELV_MQUEUE_MAY; | |
1869 | #endif | |
1870 | } | |
1871 | ||
1872 | static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) | |
1873 | { | |
1874 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1875 | struct task_struct *tsk = current; | |
1876 | struct cfq_queue *cfqq; | |
1877 | ||
1878 | /* | |
1879 | * don't force setup of a queue from here, as a call to may_queue | |
1880 | * does not necessarily imply that a request actually will be queued. | |
1881 | * so just lookup a possibly existing queue, or return 'may queue' | |
1882 | * if that fails | |
1883 | */ | |
1884 | cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw)); | |
1885 | if (cfqq) { | |
1886 | cfq_init_prio_data(cfqq); | |
1887 | cfq_prio_boost(cfqq); | |
1888 | ||
1889 | return __cfq_may_queue(cfqd, cfqq, tsk, rw); | |
1890 | } | |
1891 | ||
1892 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1893 | } |
1894 | ||
1895 | static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) | |
1896 | { | |
22e2c507 | 1897 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1da177e4 | 1898 | struct request_list *rl = &q->rq; |
1da177e4 | 1899 | |
22e2c507 JA |
1900 | if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { |
1901 | smp_mb(); | |
1902 | if (waitqueue_active(&rl->wait[READ])) | |
1903 | wake_up(&rl->wait[READ]); | |
1904 | } | |
1905 | ||
1906 | if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { | |
1907 | smp_mb(); | |
1908 | if (waitqueue_active(&rl->wait[WRITE])) | |
1909 | wake_up(&rl->wait[WRITE]); | |
1910 | } | |
1da177e4 LT |
1911 | } |
1912 | ||
1913 | /* | |
1914 | * queue lock held here | |
1915 | */ | |
1916 | static void cfq_put_request(request_queue_t *q, struct request *rq) | |
1917 | { | |
1918 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1919 | struct cfq_rq *crq = RQ_DATA(rq); | |
1920 | ||
1921 | if (crq) { | |
1922 | struct cfq_queue *cfqq = crq->cfq_queue; | |
22e2c507 | 1923 | const int rw = rq_data_dir(rq); |
1da177e4 | 1924 | |
22e2c507 JA |
1925 | BUG_ON(!cfqq->allocated[rw]); |
1926 | cfqq->allocated[rw]--; | |
1da177e4 | 1927 | |
22e2c507 | 1928 | put_io_context(crq->io_context->ioc); |
1da177e4 LT |
1929 | |
1930 | mempool_free(crq, cfqd->crq_pool); | |
1931 | rq->elevator_private = NULL; | |
1932 | ||
1da177e4 LT |
1933 | cfq_check_waiters(q, cfqq); |
1934 | cfq_put_queue(cfqq); | |
1935 | } | |
1936 | } | |
1937 | ||
1938 | /* | |
22e2c507 | 1939 | * Allocate cfq data structures associated with this request. |
1da177e4 | 1940 | */ |
22e2c507 JA |
1941 | static int |
1942 | cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, | |
1943 | int gfp_mask) | |
1da177e4 LT |
1944 | { |
1945 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1946 | struct cfq_io_context *cic; | |
1947 | const int rw = rq_data_dir(rq); | |
22e2c507 | 1948 | struct cfq_queue *cfqq; |
1da177e4 LT |
1949 | struct cfq_rq *crq; |
1950 | unsigned long flags; | |
1951 | ||
1952 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1953 | ||
22e2c507 JA |
1954 | cic = cfq_get_io_context(cfqd, cfq_queue_pid(current, rw), gfp_mask); |
1955 | ||
1da177e4 LT |
1956 | spin_lock_irqsave(q->queue_lock, flags); |
1957 | ||
22e2c507 JA |
1958 | if (!cic) |
1959 | goto queue_fail; | |
1960 | ||
1961 | if (!cic->cfqq) { | |
1962 | cfqq = cfq_get_queue(cfqd, current->pid, gfp_mask); | |
1963 | if (!cfqq) | |
1964 | goto queue_fail; | |
1da177e4 | 1965 | |
22e2c507 JA |
1966 | cic->cfqq = cfqq; |
1967 | } else | |
1968 | cfqq = cic->cfqq; | |
1da177e4 LT |
1969 | |
1970 | cfqq->allocated[rw]++; | |
22e2c507 JA |
1971 | cfqq->must_alloc = 0; |
1972 | cfqd->rq_starved = 0; | |
1973 | atomic_inc(&cfqq->ref); | |
1da177e4 LT |
1974 | spin_unlock_irqrestore(q->queue_lock, flags); |
1975 | ||
1da177e4 LT |
1976 | crq = mempool_alloc(cfqd->crq_pool, gfp_mask); |
1977 | if (crq) { | |
1978 | RB_CLEAR(&crq->rb_node); | |
1979 | crq->rb_key = 0; | |
1980 | crq->request = rq; | |
1981 | INIT_HLIST_NODE(&crq->hash); | |
1982 | crq->cfq_queue = cfqq; | |
1983 | crq->io_context = cic; | |
22e2c507 JA |
1984 | crq->in_flight = crq->accounted = 0; |
1985 | crq->is_sync = (rw == READ || process_sync(current)); | |
1986 | crq->requeued = 0; | |
1da177e4 | 1987 | rq->elevator_private = crq; |
1da177e4 LT |
1988 | return 0; |
1989 | } | |
1990 | ||
1da177e4 LT |
1991 | spin_lock_irqsave(q->queue_lock, flags); |
1992 | cfqq->allocated[rw]--; | |
22e2c507 JA |
1993 | if (!(cfqq->allocated[0] + cfqq->allocated[1])) |
1994 | cfqq->must_alloc = 1; | |
1da177e4 | 1995 | cfq_put_queue(cfqq); |
22e2c507 JA |
1996 | queue_fail: |
1997 | if (cic) | |
1998 | put_io_context(cic->ioc); | |
1999 | /* | |
2000 | * mark us rq allocation starved. we need to kickstart the process | |
2001 | * ourselves if there are no pending requests that can do it for us. | |
2002 | * that would be an extremely rare OOM situation | |
2003 | */ | |
2004 | cfqd->rq_starved = 1; | |
2005 | kblockd_schedule_work(&cfqd->unplug_work); | |
1da177e4 LT |
2006 | spin_unlock_irqrestore(q->queue_lock, flags); |
2007 | return 1; | |
2008 | } | |
2009 | ||
22e2c507 JA |
2010 | static void cfq_kick_queue(void *data) |
2011 | { | |
2012 | request_queue_t *q = data; | |
2013 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2014 | unsigned long flags; | |
2015 | ||
2016 | spin_lock_irqsave(q->queue_lock, flags); | |
2017 | ||
2018 | if (cfqd->rq_starved) { | |
2019 | struct request_list *rl = &q->rq; | |
2020 | ||
2021 | /* | |
2022 | * we aren't guaranteed to get a request after this, but we | |
2023 | * have to be opportunistic | |
2024 | */ | |
2025 | smp_mb(); | |
2026 | if (waitqueue_active(&rl->wait[READ])) | |
2027 | wake_up(&rl->wait[READ]); | |
2028 | if (waitqueue_active(&rl->wait[WRITE])) | |
2029 | wake_up(&rl->wait[WRITE]); | |
2030 | } | |
2031 | ||
2032 | blk_remove_plug(q); | |
2033 | q->request_fn(q); | |
2034 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2035 | } | |
2036 | ||
2037 | /* | |
2038 | * Timer running if the active_queue is currently idling inside its time slice | |
2039 | */ | |
2040 | static void cfq_idle_slice_timer(unsigned long data) | |
2041 | { | |
2042 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2043 | struct cfq_queue *cfqq; | |
2044 | unsigned long flags; | |
2045 | ||
2046 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2047 | ||
2048 | if ((cfqq = cfqd->active_queue) != NULL) { | |
2049 | unsigned long now = jiffies; | |
2050 | ||
2051 | /* | |
2052 | * expired | |
2053 | */ | |
2054 | if (time_after(now, cfqq->slice_end)) | |
2055 | goto expire; | |
2056 | ||
2057 | /* | |
2058 | * only expire and reinvoke request handler, if there are | |
2059 | * other queues with pending requests | |
2060 | */ | |
2061 | if (!cfq_pending_requests(cfqd)) { | |
2062 | cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); | |
2063 | add_timer(&cfqd->idle_slice_timer); | |
2064 | goto out_cont; | |
2065 | } | |
2066 | ||
2067 | /* | |
2068 | * not expired and it has a request pending, let it dispatch | |
2069 | */ | |
2070 | if (!RB_EMPTY(&cfqq->sort_list)) { | |
2071 | cfqq->must_dispatch = 1; | |
2072 | goto out_kick; | |
2073 | } | |
2074 | } | |
2075 | expire: | |
2076 | cfq_slice_expired(cfqd, 0); | |
2077 | out_kick: | |
2078 | if (cfq_pending_requests(cfqd)) | |
2079 | kblockd_schedule_work(&cfqd->unplug_work); | |
2080 | out_cont: | |
2081 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2082 | } | |
2083 | ||
2084 | /* | |
2085 | * Timer running if an idle class queue is waiting for service | |
2086 | */ | |
2087 | static void cfq_idle_class_timer(unsigned long data) | |
2088 | { | |
2089 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2090 | unsigned long flags, end; | |
2091 | ||
2092 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2093 | ||
2094 | /* | |
2095 | * race with a non-idle queue, reset timer | |
2096 | */ | |
2097 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
2098 | if (!time_after_eq(jiffies, end)) { | |
2099 | cfqd->idle_class_timer.expires = end; | |
2100 | add_timer(&cfqd->idle_class_timer); | |
2101 | } else | |
2102 | kblockd_schedule_work(&cfqd->unplug_work); | |
2103 | ||
2104 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2105 | } | |
2106 | ||
2107 | ||
1da177e4 LT |
2108 | static void cfq_put_cfqd(struct cfq_data *cfqd) |
2109 | { | |
2110 | request_queue_t *q = cfqd->queue; | |
2111 | ||
2112 | if (!atomic_dec_and_test(&cfqd->ref)) | |
2113 | return; | |
2114 | ||
22e2c507 JA |
2115 | blk_sync_queue(q); |
2116 | ||
1da177e4 LT |
2117 | blk_put_queue(q); |
2118 | ||
2119 | mempool_destroy(cfqd->crq_pool); | |
2120 | kfree(cfqd->crq_hash); | |
2121 | kfree(cfqd->cfq_hash); | |
2122 | kfree(cfqd); | |
2123 | } | |
2124 | ||
2125 | static void cfq_exit_queue(elevator_t *e) | |
2126 | { | |
22e2c507 JA |
2127 | struct cfq_data *cfqd = e->elevator_data; |
2128 | ||
2129 | del_timer_sync(&cfqd->idle_slice_timer); | |
2130 | del_timer_sync(&cfqd->idle_class_timer); | |
2131 | cfq_put_cfqd(cfqd); | |
1da177e4 LT |
2132 | } |
2133 | ||
2134 | static int cfq_init_queue(request_queue_t *q, elevator_t *e) | |
2135 | { | |
2136 | struct cfq_data *cfqd; | |
2137 | int i; | |
2138 | ||
2139 | cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); | |
2140 | if (!cfqd) | |
2141 | return -ENOMEM; | |
2142 | ||
2143 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 JA |
2144 | |
2145 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2146 | INIT_LIST_HEAD(&cfqd->rr_list[i]); | |
2147 | ||
2148 | INIT_LIST_HEAD(&cfqd->busy_rr); | |
2149 | INIT_LIST_HEAD(&cfqd->cur_rr); | |
2150 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
1da177e4 LT |
2151 | INIT_LIST_HEAD(&cfqd->empty_list); |
2152 | ||
2153 | cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); | |
2154 | if (!cfqd->crq_hash) | |
2155 | goto out_crqhash; | |
2156 | ||
2157 | cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); | |
2158 | if (!cfqd->cfq_hash) | |
2159 | goto out_cfqhash; | |
2160 | ||
2161 | cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool); | |
2162 | if (!cfqd->crq_pool) | |
2163 | goto out_crqpool; | |
2164 | ||
2165 | for (i = 0; i < CFQ_MHASH_ENTRIES; i++) | |
2166 | INIT_HLIST_HEAD(&cfqd->crq_hash[i]); | |
2167 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) | |
2168 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2169 | ||
2170 | e->elevator_data = cfqd; | |
2171 | ||
2172 | cfqd->queue = q; | |
2173 | atomic_inc(&q->refcnt); | |
2174 | ||
22e2c507 | 2175 | cfqd->max_queued = q->nr_requests / 4; |
1da177e4 | 2176 | q->nr_batching = cfq_queued; |
22e2c507 JA |
2177 | |
2178 | init_timer(&cfqd->idle_slice_timer); | |
2179 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2180 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2181 | ||
2182 | init_timer(&cfqd->idle_class_timer); | |
2183 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2184 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2185 | ||
2186 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); | |
2187 | ||
1da177e4 LT |
2188 | atomic_set(&cfqd->ref, 1); |
2189 | ||
2190 | cfqd->cfq_queued = cfq_queued; | |
2191 | cfqd->cfq_quantum = cfq_quantum; | |
22e2c507 JA |
2192 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2193 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2194 | cfqd->cfq_back_max = cfq_back_max; |
2195 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2196 | cfqd->cfq_slice[0] = cfq_slice_async; |
2197 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2198 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2199 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
2200 | cfqd->cfq_max_depth = cfq_max_depth; | |
1da177e4 LT |
2201 | return 0; |
2202 | out_crqpool: | |
2203 | kfree(cfqd->cfq_hash); | |
2204 | out_cfqhash: | |
2205 | kfree(cfqd->crq_hash); | |
2206 | out_crqhash: | |
2207 | kfree(cfqd); | |
2208 | return -ENOMEM; | |
2209 | } | |
2210 | ||
2211 | static void cfq_slab_kill(void) | |
2212 | { | |
2213 | if (crq_pool) | |
2214 | kmem_cache_destroy(crq_pool); | |
2215 | if (cfq_pool) | |
2216 | kmem_cache_destroy(cfq_pool); | |
2217 | if (cfq_ioc_pool) | |
2218 | kmem_cache_destroy(cfq_ioc_pool); | |
2219 | } | |
2220 | ||
2221 | static int __init cfq_slab_setup(void) | |
2222 | { | |
2223 | crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, | |
2224 | NULL, NULL); | |
2225 | if (!crq_pool) | |
2226 | goto fail; | |
2227 | ||
2228 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, | |
2229 | NULL, NULL); | |
2230 | if (!cfq_pool) | |
2231 | goto fail; | |
2232 | ||
2233 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2234 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2235 | if (!cfq_ioc_pool) | |
2236 | goto fail; | |
2237 | ||
2238 | return 0; | |
2239 | fail: | |
2240 | cfq_slab_kill(); | |
2241 | return -ENOMEM; | |
2242 | } | |
2243 | ||
1da177e4 LT |
2244 | /* |
2245 | * sysfs parts below --> | |
2246 | */ | |
2247 | struct cfq_fs_entry { | |
2248 | struct attribute attr; | |
2249 | ssize_t (*show)(struct cfq_data *, char *); | |
2250 | ssize_t (*store)(struct cfq_data *, const char *, size_t); | |
2251 | }; | |
2252 | ||
2253 | static ssize_t | |
2254 | cfq_var_show(unsigned int var, char *page) | |
2255 | { | |
2256 | return sprintf(page, "%d\n", var); | |
2257 | } | |
2258 | ||
2259 | static ssize_t | |
2260 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2261 | { | |
2262 | char *p = (char *) page; | |
2263 | ||
2264 | *var = simple_strtoul(p, &p, 10); | |
2265 | return count; | |
2266 | } | |
2267 | ||
1da177e4 LT |
2268 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
2269 | static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \ | |
2270 | { \ | |
2271 | unsigned int __data = __VAR; \ | |
2272 | if (__CONV) \ | |
2273 | __data = jiffies_to_msecs(__data); \ | |
2274 | return cfq_var_show(__data, (page)); \ | |
2275 | } | |
2276 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
2277 | SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); | |
22e2c507 JA |
2278 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2279 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
1da177e4 LT |
2280 | SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); |
2281 | SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2282 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2283 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2284 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2285 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
2286 | SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0); | |
1da177e4 LT |
2287 | #undef SHOW_FUNCTION |
2288 | ||
2289 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
2290 | static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \ | |
2291 | { \ | |
2292 | unsigned int __data; \ | |
2293 | int ret = cfq_var_store(&__data, (page), count); \ | |
2294 | if (__data < (MIN)) \ | |
2295 | __data = (MIN); \ | |
2296 | else if (__data > (MAX)) \ | |
2297 | __data = (MAX); \ | |
2298 | if (__CONV) \ | |
2299 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2300 | else \ | |
2301 | *(__PTR) = __data; \ | |
2302 | return ret; \ | |
2303 | } | |
2304 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
2305 | STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); | |
22e2c507 JA |
2306 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2307 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
1da177e4 LT |
2308 | STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2309 | STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2310 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2311 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2312 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2313 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
2314 | STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0); | |
1da177e4 LT |
2315 | #undef STORE_FUNCTION |
2316 | ||
2317 | static struct cfq_fs_entry cfq_quantum_entry = { | |
2318 | .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR }, | |
2319 | .show = cfq_quantum_show, | |
2320 | .store = cfq_quantum_store, | |
2321 | }; | |
2322 | static struct cfq_fs_entry cfq_queued_entry = { | |
2323 | .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR }, | |
2324 | .show = cfq_queued_show, | |
2325 | .store = cfq_queued_store, | |
2326 | }; | |
22e2c507 | 2327 | static struct cfq_fs_entry cfq_fifo_expire_sync_entry = { |
1da177e4 | 2328 | .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR }, |
22e2c507 JA |
2329 | .show = cfq_fifo_expire_sync_show, |
2330 | .store = cfq_fifo_expire_sync_store, | |
1da177e4 | 2331 | }; |
22e2c507 | 2332 | static struct cfq_fs_entry cfq_fifo_expire_async_entry = { |
1da177e4 | 2333 | .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR }, |
22e2c507 JA |
2334 | .show = cfq_fifo_expire_async_show, |
2335 | .store = cfq_fifo_expire_async_store, | |
1da177e4 LT |
2336 | }; |
2337 | static struct cfq_fs_entry cfq_back_max_entry = { | |
2338 | .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR }, | |
2339 | .show = cfq_back_max_show, | |
2340 | .store = cfq_back_max_store, | |
2341 | }; | |
2342 | static struct cfq_fs_entry cfq_back_penalty_entry = { | |
2343 | .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR }, | |
2344 | .show = cfq_back_penalty_show, | |
2345 | .store = cfq_back_penalty_store, | |
2346 | }; | |
22e2c507 JA |
2347 | static struct cfq_fs_entry cfq_slice_sync_entry = { |
2348 | .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR }, | |
2349 | .show = cfq_slice_sync_show, | |
2350 | .store = cfq_slice_sync_store, | |
1da177e4 | 2351 | }; |
22e2c507 JA |
2352 | static struct cfq_fs_entry cfq_slice_async_entry = { |
2353 | .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR }, | |
2354 | .show = cfq_slice_async_show, | |
2355 | .store = cfq_slice_async_store, | |
2356 | }; | |
2357 | static struct cfq_fs_entry cfq_slice_async_rq_entry = { | |
2358 | .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR }, | |
2359 | .show = cfq_slice_async_rq_show, | |
2360 | .store = cfq_slice_async_rq_store, | |
2361 | }; | |
2362 | static struct cfq_fs_entry cfq_slice_idle_entry = { | |
2363 | .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR }, | |
2364 | .show = cfq_slice_idle_show, | |
2365 | .store = cfq_slice_idle_store, | |
2366 | }; | |
2367 | static struct cfq_fs_entry cfq_max_depth_entry = { | |
2368 | .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR }, | |
2369 | .show = cfq_max_depth_show, | |
2370 | .store = cfq_max_depth_store, | |
1da177e4 | 2371 | }; |
1da177e4 LT |
2372 | static struct attribute *default_attrs[] = { |
2373 | &cfq_quantum_entry.attr, | |
2374 | &cfq_queued_entry.attr, | |
22e2c507 JA |
2375 | &cfq_fifo_expire_sync_entry.attr, |
2376 | &cfq_fifo_expire_async_entry.attr, | |
1da177e4 LT |
2377 | &cfq_back_max_entry.attr, |
2378 | &cfq_back_penalty_entry.attr, | |
22e2c507 JA |
2379 | &cfq_slice_sync_entry.attr, |
2380 | &cfq_slice_async_entry.attr, | |
2381 | &cfq_slice_async_rq_entry.attr, | |
2382 | &cfq_slice_idle_entry.attr, | |
2383 | &cfq_max_depth_entry.attr, | |
1da177e4 LT |
2384 | NULL, |
2385 | }; | |
2386 | ||
2387 | #define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr) | |
2388 | ||
2389 | static ssize_t | |
2390 | cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
2391 | { | |
2392 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
2393 | struct cfq_fs_entry *entry = to_cfq(attr); | |
2394 | ||
2395 | if (!entry->show) | |
6c1852a0 | 2396 | return -EIO; |
1da177e4 LT |
2397 | |
2398 | return entry->show(e->elevator_data, page); | |
2399 | } | |
2400 | ||
2401 | static ssize_t | |
2402 | cfq_attr_store(struct kobject *kobj, struct attribute *attr, | |
2403 | const char *page, size_t length) | |
2404 | { | |
2405 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
2406 | struct cfq_fs_entry *entry = to_cfq(attr); | |
2407 | ||
2408 | if (!entry->store) | |
6c1852a0 | 2409 | return -EIO; |
1da177e4 LT |
2410 | |
2411 | return entry->store(e->elevator_data, page, length); | |
2412 | } | |
2413 | ||
2414 | static struct sysfs_ops cfq_sysfs_ops = { | |
2415 | .show = cfq_attr_show, | |
2416 | .store = cfq_attr_store, | |
2417 | }; | |
2418 | ||
2419 | static struct kobj_type cfq_ktype = { | |
2420 | .sysfs_ops = &cfq_sysfs_ops, | |
2421 | .default_attrs = default_attrs, | |
2422 | }; | |
2423 | ||
2424 | static struct elevator_type iosched_cfq = { | |
2425 | .ops = { | |
2426 | .elevator_merge_fn = cfq_merge, | |
2427 | .elevator_merged_fn = cfq_merged_request, | |
2428 | .elevator_merge_req_fn = cfq_merged_requests, | |
2429 | .elevator_next_req_fn = cfq_next_request, | |
2430 | .elevator_add_req_fn = cfq_insert_request, | |
2431 | .elevator_remove_req_fn = cfq_remove_request, | |
2432 | .elevator_requeue_req_fn = cfq_requeue_request, | |
2433 | .elevator_deactivate_req_fn = cfq_deactivate_request, | |
2434 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2435 | .elevator_completed_req_fn = cfq_completed_request, | |
2436 | .elevator_former_req_fn = cfq_former_request, | |
2437 | .elevator_latter_req_fn = cfq_latter_request, | |
2438 | .elevator_set_req_fn = cfq_set_request, | |
2439 | .elevator_put_req_fn = cfq_put_request, | |
2440 | .elevator_may_queue_fn = cfq_may_queue, | |
2441 | .elevator_init_fn = cfq_init_queue, | |
2442 | .elevator_exit_fn = cfq_exit_queue, | |
2443 | }, | |
2444 | .elevator_ktype = &cfq_ktype, | |
2445 | .elevator_name = "cfq", | |
2446 | .elevator_owner = THIS_MODULE, | |
2447 | }; | |
2448 | ||
2449 | static int __init cfq_init(void) | |
2450 | { | |
2451 | int ret; | |
2452 | ||
22e2c507 JA |
2453 | /* |
2454 | * could be 0 on HZ < 1000 setups | |
2455 | */ | |
2456 | if (!cfq_slice_async) | |
2457 | cfq_slice_async = 1; | |
2458 | if (!cfq_slice_idle) | |
2459 | cfq_slice_idle = 1; | |
2460 | ||
1da177e4 LT |
2461 | if (cfq_slab_setup()) |
2462 | return -ENOMEM; | |
2463 | ||
2464 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2465 | if (ret) |
2466 | cfq_slab_kill(); | |
1da177e4 | 2467 | |
1da177e4 LT |
2468 | return ret; |
2469 | } | |
2470 | ||
2471 | static void __exit cfq_exit(void) | |
2472 | { | |
22e2c507 JA |
2473 | struct task_struct *g, *p; |
2474 | unsigned long flags; | |
2475 | ||
2476 | read_lock_irqsave(&tasklist_lock, flags); | |
2477 | ||
2478 | /* | |
2479 | * iterate each process in the system, removing our io_context | |
2480 | */ | |
2481 | do_each_thread(g, p) { | |
2482 | struct io_context *ioc = p->io_context; | |
2483 | ||
2484 | if (ioc && ioc->cic) { | |
2485 | ioc->cic->exit(ioc->cic); | |
2486 | cfq_free_io_context(ioc->cic); | |
2487 | ioc->cic = NULL; | |
2488 | } | |
2489 | } while_each_thread(g, p); | |
2490 | ||
2491 | read_unlock_irqrestore(&tasklist_lock, flags); | |
2492 | ||
1da177e4 LT |
2493 | cfq_slab_kill(); |
2494 | elv_unregister(&iosched_cfq); | |
2495 | } | |
2496 | ||
2497 | module_init(cfq_init); | |
2498 | module_exit(cfq_exit); | |
2499 | ||
2500 | MODULE_AUTHOR("Jens Axboe"); | |
2501 | MODULE_LICENSE("GPL"); | |
2502 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |