Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * CFQ, or complete fairness queueing, disk scheduler. |
3 | * | |
4 | * Based on ideas from a previously unfinished io | |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
6 | * | |
0fe23479 | 7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
1da177e4 | 8 | */ |
1da177e4 | 9 | #include <linux/module.h> |
1cc9be68 AV |
10 | #include <linux/blkdev.h> |
11 | #include <linux/elevator.h> | |
1da177e4 LT |
12 | #include <linux/hash.h> |
13 | #include <linux/rbtree.h> | |
22e2c507 | 14 | #include <linux/ioprio.h> |
1da177e4 LT |
15 | |
16 | /* | |
17 | * tunables | |
18 | */ | |
64100099 | 19 | static const int cfq_quantum = 4; /* max queue in one round of service */ |
64100099 AV |
20 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
21 | static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ | |
22 | static const int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
1da177e4 | 23 | |
64100099 | 24 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 25 | static int cfq_slice_async = HZ / 25; |
64100099 | 26 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 27 | static int cfq_slice_idle = HZ / 125; |
22e2c507 | 28 | |
d9e7620e JA |
29 | /* |
30 | * grace period before allowing idle class to get disk access | |
31 | */ | |
22e2c507 | 32 | #define CFQ_IDLE_GRACE (HZ / 10) |
d9e7620e JA |
33 | |
34 | /* | |
35 | * below this threshold, we consider thinktime immediate | |
36 | */ | |
37 | #define CFQ_MIN_TT (2) | |
38 | ||
22e2c507 JA |
39 | #define CFQ_SLICE_SCALE (5) |
40 | ||
41 | #define CFQ_KEY_ASYNC (0) | |
22e2c507 | 42 | |
1da177e4 LT |
43 | /* |
44 | * for the hash of cfqq inside the cfqd | |
45 | */ | |
46 | #define CFQ_QHASH_SHIFT 6 | |
47 | #define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) | |
48 | #define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) | |
49 | ||
1da177e4 LT |
50 | #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) |
51 | ||
5e705374 JA |
52 | #define RQ_CIC(rq) ((struct cfq_io_context*)(rq)->elevator_private) |
53 | #define RQ_CFQQ(rq) ((rq)->elevator_private2) | |
1da177e4 | 54 | |
e18b890b CL |
55 | static struct kmem_cache *cfq_pool; |
56 | static struct kmem_cache *cfq_ioc_pool; | |
1da177e4 | 57 | |
4050cf16 | 58 | static DEFINE_PER_CPU(unsigned long, ioc_count); |
334e94de AV |
59 | static struct completion *ioc_gone; |
60 | ||
22e2c507 JA |
61 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
62 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
22e2c507 JA |
63 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
64 | ||
3b18152c JA |
65 | #define ASYNC (0) |
66 | #define SYNC (1) | |
67 | ||
6d048f53 | 68 | #define cfq_cfqq_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) |
22e2c507 | 69 | |
206dc69b JA |
70 | #define sample_valid(samples) ((samples) > 80) |
71 | ||
22e2c507 JA |
72 | /* |
73 | * Per block device queue structure | |
74 | */ | |
1da177e4 | 75 | struct cfq_data { |
22e2c507 JA |
76 | request_queue_t *queue; |
77 | ||
78 | /* | |
79 | * rr list of queues with requests and the count of them | |
80 | */ | |
d9e7620e | 81 | struct rb_root service_tree; |
22e2c507 JA |
82 | struct list_head cur_rr; |
83 | struct list_head idle_rr; | |
84 | unsigned int busy_queues; | |
85 | ||
22e2c507 JA |
86 | /* |
87 | * cfqq lookup hash | |
88 | */ | |
1da177e4 | 89 | struct hlist_head *cfq_hash; |
1da177e4 | 90 | |
22e2c507 | 91 | int rq_in_driver; |
25776e35 | 92 | int hw_tag; |
1da177e4 | 93 | |
22e2c507 JA |
94 | /* |
95 | * idle window management | |
96 | */ | |
97 | struct timer_list idle_slice_timer; | |
98 | struct work_struct unplug_work; | |
1da177e4 | 99 | |
22e2c507 JA |
100 | struct cfq_queue *active_queue; |
101 | struct cfq_io_context *active_cic; | |
22e2c507 JA |
102 | unsigned int dispatch_slice; |
103 | ||
104 | struct timer_list idle_class_timer; | |
1da177e4 | 105 | |
6d048f53 | 106 | sector_t last_position; |
22e2c507 | 107 | unsigned long last_end_request; |
1da177e4 | 108 | |
1da177e4 LT |
109 | /* |
110 | * tunables, see top of file | |
111 | */ | |
112 | unsigned int cfq_quantum; | |
22e2c507 | 113 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
114 | unsigned int cfq_back_penalty; |
115 | unsigned int cfq_back_max; | |
22e2c507 JA |
116 | unsigned int cfq_slice[2]; |
117 | unsigned int cfq_slice_async_rq; | |
118 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
119 | |
120 | struct list_head cic_list; | |
6d048f53 JA |
121 | |
122 | sector_t new_seek_mean; | |
123 | u64 new_seek_total; | |
1da177e4 LT |
124 | }; |
125 | ||
22e2c507 JA |
126 | /* |
127 | * Per process-grouping structure | |
128 | */ | |
1da177e4 LT |
129 | struct cfq_queue { |
130 | /* reference count */ | |
131 | atomic_t ref; | |
132 | /* parent cfq_data */ | |
133 | struct cfq_data *cfqd; | |
22e2c507 | 134 | /* cfqq lookup hash */ |
1da177e4 LT |
135 | struct hlist_node cfq_hash; |
136 | /* hash key */ | |
22e2c507 | 137 | unsigned int key; |
981a7973 | 138 | /* member of the rr/busy/cur/idle cfqd list */ |
1da177e4 | 139 | struct list_head cfq_list; |
d9e7620e JA |
140 | /* service_tree member */ |
141 | struct rb_node rb_node; | |
142 | /* service_tree key */ | |
143 | unsigned long rb_key; | |
1da177e4 LT |
144 | /* sorted list of pending requests */ |
145 | struct rb_root sort_list; | |
146 | /* if fifo isn't expired, next request to serve */ | |
5e705374 | 147 | struct request *next_rq; |
1da177e4 LT |
148 | /* requests queued in sort_list */ |
149 | int queued[2]; | |
150 | /* currently allocated requests */ | |
151 | int allocated[2]; | |
374f84ac JA |
152 | /* pending metadata requests */ |
153 | int meta_pending; | |
1da177e4 | 154 | /* fifo list of requests in sort_list */ |
22e2c507 | 155 | struct list_head fifo; |
1da177e4 | 156 | |
22e2c507 | 157 | unsigned long slice_end; |
c5b680f3 | 158 | long slice_resid; |
1da177e4 | 159 | |
6d048f53 JA |
160 | /* number of requests that are on the dispatch list or inside driver */ |
161 | int dispatched; | |
22e2c507 JA |
162 | |
163 | /* io prio of this group */ | |
164 | unsigned short ioprio, org_ioprio; | |
165 | unsigned short ioprio_class, org_ioprio_class; | |
166 | ||
3b18152c JA |
167 | /* various state flags, see below */ |
168 | unsigned int flags; | |
6d048f53 JA |
169 | |
170 | sector_t last_request_pos; | |
1da177e4 LT |
171 | }; |
172 | ||
3b18152c | 173 | enum cfqq_state_flags { |
b0b8d749 JA |
174 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
175 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
176 | CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ | |
177 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ | |
178 | CFQ_CFQQ_FLAG_must_dispatch, /* must dispatch, even if expired */ | |
179 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ | |
180 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
181 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
182 | CFQ_CFQQ_FLAG_queue_new, /* queue never been serviced */ | |
44f7c160 | 183 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
3b18152c JA |
184 | }; |
185 | ||
186 | #define CFQ_CFQQ_FNS(name) \ | |
187 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
188 | { \ | |
189 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
190 | } \ | |
191 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
192 | { \ | |
193 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
194 | } \ | |
195 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
196 | { \ | |
197 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
198 | } | |
199 | ||
200 | CFQ_CFQQ_FNS(on_rr); | |
201 | CFQ_CFQQ_FNS(wait_request); | |
202 | CFQ_CFQQ_FNS(must_alloc); | |
203 | CFQ_CFQQ_FNS(must_alloc_slice); | |
204 | CFQ_CFQQ_FNS(must_dispatch); | |
205 | CFQ_CFQQ_FNS(fifo_expire); | |
206 | CFQ_CFQQ_FNS(idle_window); | |
207 | CFQ_CFQQ_FNS(prio_changed); | |
53b03744 | 208 | CFQ_CFQQ_FNS(queue_new); |
44f7c160 | 209 | CFQ_CFQQ_FNS(slice_new); |
3b18152c JA |
210 | #undef CFQ_CFQQ_FNS |
211 | ||
3b18152c | 212 | static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); |
5e705374 | 213 | static void cfq_dispatch_insert(request_queue_t *, struct request *); |
6f325a13 | 214 | static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); |
1da177e4 | 215 | |
99f95e52 AM |
216 | /* |
217 | * scheduler run of queue, if there are requests pending and no one in the | |
218 | * driver that will restart queueing | |
219 | */ | |
220 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
221 | { | |
7b14e3b5 | 222 | if (cfqd->busy_queues) |
99f95e52 AM |
223 | kblockd_schedule_work(&cfqd->unplug_work); |
224 | } | |
225 | ||
226 | static int cfq_queue_empty(request_queue_t *q) | |
227 | { | |
228 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
229 | ||
b4878f24 | 230 | return !cfqd->busy_queues; |
99f95e52 AM |
231 | } |
232 | ||
7749a8d4 | 233 | static inline pid_t cfq_queue_pid(struct task_struct *task, int rw, int is_sync) |
206dc69b | 234 | { |
7749a8d4 JA |
235 | /* |
236 | * Use the per-process queue, for read requests and syncronous writes | |
237 | */ | |
238 | if (!(rw & REQ_RW) || is_sync) | |
206dc69b JA |
239 | return task->pid; |
240 | ||
241 | return CFQ_KEY_ASYNC; | |
242 | } | |
243 | ||
44f7c160 JA |
244 | /* |
245 | * Scale schedule slice based on io priority. Use the sync time slice only | |
246 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
247 | * io only, should not get full sync slice length. | |
248 | */ | |
d9e7620e JA |
249 | static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync, |
250 | unsigned short prio) | |
44f7c160 | 251 | { |
d9e7620e | 252 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 253 | |
d9e7620e JA |
254 | WARN_ON(prio >= IOPRIO_BE_NR); |
255 | ||
256 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
257 | } | |
44f7c160 | 258 | |
d9e7620e JA |
259 | static inline int |
260 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
261 | { | |
262 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
263 | } |
264 | ||
265 | static inline void | |
266 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
267 | { | |
268 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
269 | } | |
270 | ||
271 | /* | |
272 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
273 | * isn't valid until the first request from the dispatch is activated | |
274 | * and the slice time set. | |
275 | */ | |
276 | static inline int cfq_slice_used(struct cfq_queue *cfqq) | |
277 | { | |
278 | if (cfq_cfqq_slice_new(cfqq)) | |
279 | return 0; | |
280 | if (time_before(jiffies, cfqq->slice_end)) | |
281 | return 0; | |
282 | ||
283 | return 1; | |
284 | } | |
285 | ||
1da177e4 | 286 | /* |
5e705374 | 287 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 288 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 289 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 290 | */ |
5e705374 JA |
291 | static struct request * |
292 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
1da177e4 LT |
293 | { |
294 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 295 | unsigned long back_max; |
e8a99053 AM |
296 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
297 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
298 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 299 | |
5e705374 JA |
300 | if (rq1 == NULL || rq1 == rq2) |
301 | return rq2; | |
302 | if (rq2 == NULL) | |
303 | return rq1; | |
9c2c38a1 | 304 | |
5e705374 JA |
305 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
306 | return rq1; | |
307 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
308 | return rq2; | |
374f84ac JA |
309 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
310 | return rq1; | |
311 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
312 | return rq2; | |
1da177e4 | 313 | |
5e705374 JA |
314 | s1 = rq1->sector; |
315 | s2 = rq2->sector; | |
1da177e4 | 316 | |
6d048f53 | 317 | last = cfqd->last_position; |
1da177e4 | 318 | |
1da177e4 LT |
319 | /* |
320 | * by definition, 1KiB is 2 sectors | |
321 | */ | |
322 | back_max = cfqd->cfq_back_max * 2; | |
323 | ||
324 | /* | |
325 | * Strict one way elevator _except_ in the case where we allow | |
326 | * short backward seeks which are biased as twice the cost of a | |
327 | * similar forward seek. | |
328 | */ | |
329 | if (s1 >= last) | |
330 | d1 = s1 - last; | |
331 | else if (s1 + back_max >= last) | |
332 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
333 | else | |
e8a99053 | 334 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
335 | |
336 | if (s2 >= last) | |
337 | d2 = s2 - last; | |
338 | else if (s2 + back_max >= last) | |
339 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
340 | else | |
e8a99053 | 341 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
342 | |
343 | /* Found required data */ | |
e8a99053 AM |
344 | |
345 | /* | |
346 | * By doing switch() on the bit mask "wrap" we avoid having to | |
347 | * check two variables for all permutations: --> faster! | |
348 | */ | |
349 | switch (wrap) { | |
5e705374 | 350 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 351 | if (d1 < d2) |
5e705374 | 352 | return rq1; |
e8a99053 | 353 | else if (d2 < d1) |
5e705374 | 354 | return rq2; |
e8a99053 AM |
355 | else { |
356 | if (s1 >= s2) | |
5e705374 | 357 | return rq1; |
e8a99053 | 358 | else |
5e705374 | 359 | return rq2; |
e8a99053 | 360 | } |
1da177e4 | 361 | |
e8a99053 | 362 | case CFQ_RQ2_WRAP: |
5e705374 | 363 | return rq1; |
e8a99053 | 364 | case CFQ_RQ1_WRAP: |
5e705374 JA |
365 | return rq2; |
366 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
367 | default: |
368 | /* | |
369 | * Since both rqs are wrapped, | |
370 | * start with the one that's further behind head | |
371 | * (--> only *one* back seek required), | |
372 | * since back seek takes more time than forward. | |
373 | */ | |
374 | if (s1 <= s2) | |
5e705374 | 375 | return rq1; |
1da177e4 | 376 | else |
5e705374 | 377 | return rq2; |
1da177e4 LT |
378 | } |
379 | } | |
380 | ||
381 | /* | |
382 | * would be nice to take fifo expire time into account as well | |
383 | */ | |
5e705374 JA |
384 | static struct request * |
385 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
386 | struct request *last) | |
1da177e4 | 387 | { |
21183b07 JA |
388 | struct rb_node *rbnext = rb_next(&last->rb_node); |
389 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 390 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 391 | |
21183b07 | 392 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
393 | |
394 | if (rbprev) | |
5e705374 | 395 | prev = rb_entry_rq(rbprev); |
1da177e4 | 396 | |
21183b07 | 397 | if (rbnext) |
5e705374 | 398 | next = rb_entry_rq(rbnext); |
21183b07 JA |
399 | else { |
400 | rbnext = rb_first(&cfqq->sort_list); | |
401 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 402 | next = rb_entry_rq(rbnext); |
21183b07 | 403 | } |
1da177e4 | 404 | |
21183b07 | 405 | return cfq_choose_req(cfqd, next, prev); |
1da177e4 LT |
406 | } |
407 | ||
d9e7620e JA |
408 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
409 | struct cfq_queue *cfqq) | |
1da177e4 | 410 | { |
d9e7620e JA |
411 | /* |
412 | * just an approximation, should be ok. | |
413 | */ | |
414 | return ((cfqd->busy_queues - 1) * cfq_prio_slice(cfqd, 1, 0)); | |
415 | } | |
416 | ||
417 | static void cfq_service_tree_add(struct cfq_data *cfqd, | |
418 | struct cfq_queue *cfqq) | |
419 | { | |
420 | struct rb_node **p = &cfqd->service_tree.rb_node; | |
421 | struct rb_node *parent = NULL; | |
422 | struct cfq_queue *__cfqq; | |
423 | unsigned long rb_key; | |
424 | ||
425 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; | |
426 | rb_key += cfqq->slice_resid; | |
427 | cfqq->slice_resid = 0; | |
1da177e4 | 428 | |
d9e7620e | 429 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 430 | /* |
d9e7620e | 431 | * same position, nothing more to do |
99f9628a | 432 | */ |
d9e7620e JA |
433 | if (rb_key == cfqq->rb_key) |
434 | return; | |
1da177e4 | 435 | |
d9e7620e | 436 | rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
1da177e4 | 437 | } |
d9e7620e JA |
438 | |
439 | while (*p) { | |
440 | parent = *p; | |
441 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
442 | ||
443 | if (rb_key < __cfqq->rb_key) | |
444 | p = &(*p)->rb_left; | |
445 | else | |
446 | p = &(*p)->rb_right; | |
447 | } | |
448 | ||
449 | cfqq->rb_key = rb_key; | |
450 | rb_link_node(&cfqq->rb_node, parent, p); | |
451 | rb_insert_color(&cfqq->rb_node, &cfqd->service_tree); | |
1da177e4 LT |
452 | } |
453 | ||
6d048f53 JA |
454 | static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) |
455 | { | |
456 | struct cfq_data *cfqd = cfqq->cfqd; | |
457 | struct list_head *n; | |
458 | ||
459 | /* | |
460 | * Resorting requires the cfqq to be on the RR list already. | |
461 | */ | |
462 | if (!cfq_cfqq_on_rr(cfqq)) | |
463 | return; | |
464 | ||
d9e7620e | 465 | list_del_init(&cfqq->cfq_list); |
6d048f53 JA |
466 | |
467 | if (cfq_class_rt(cfqq)) { | |
468 | /* | |
469 | * At to the front of the current list, but behind other | |
470 | * RT queues. | |
471 | */ | |
472 | n = &cfqd->cur_rr; | |
473 | while (n->next != &cfqd->cur_rr) | |
474 | if (!cfq_class_rt(cfqq)) | |
475 | break; | |
476 | ||
477 | list_add(&cfqq->cfq_list, n); | |
478 | } else if (cfq_class_idle(cfqq)) { | |
479 | /* | |
480 | * IDLE goes to the tail of the idle list | |
481 | */ | |
482 | list_add_tail(&cfqq->cfq_list, &cfqd->idle_rr); | |
483 | } else { | |
484 | /* | |
485 | * So we get here, ergo the queue is a regular best-effort queue | |
486 | */ | |
d9e7620e | 487 | cfq_service_tree_add(cfqd, cfqq); |
6d048f53 JA |
488 | } |
489 | } | |
490 | ||
1da177e4 LT |
491 | /* |
492 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 493 | * the pending list according to last request service |
1da177e4 LT |
494 | */ |
495 | static inline void | |
b4878f24 | 496 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 497 | { |
3b18152c JA |
498 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
499 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
500 | cfqd->busy_queues++; |
501 | ||
b4878f24 | 502 | cfq_resort_rr_list(cfqq, 0); |
1da177e4 LT |
503 | } |
504 | ||
505 | static inline void | |
506 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
507 | { | |
3b18152c JA |
508 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
509 | cfq_clear_cfqq_on_rr(cfqq); | |
981a7973 | 510 | list_del_init(&cfqq->cfq_list); |
1da177e4 | 511 | |
d9e7620e JA |
512 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
513 | rb_erase(&cfqq->rb_node, &cfqd->service_tree); | |
514 | RB_CLEAR_NODE(&cfqq->rb_node); | |
515 | } | |
516 | ||
1da177e4 LT |
517 | BUG_ON(!cfqd->busy_queues); |
518 | cfqd->busy_queues--; | |
519 | } | |
520 | ||
521 | /* | |
522 | * rb tree support functions | |
523 | */ | |
5e705374 | 524 | static inline void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 525 | { |
5e705374 | 526 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 527 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 528 | const int sync = rq_is_sync(rq); |
1da177e4 | 529 | |
b4878f24 JA |
530 | BUG_ON(!cfqq->queued[sync]); |
531 | cfqq->queued[sync]--; | |
1da177e4 | 532 | |
5e705374 | 533 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 534 | |
dd67d051 | 535 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 536 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
537 | } |
538 | ||
5e705374 | 539 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 540 | { |
5e705374 | 541 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 542 | struct cfq_data *cfqd = cfqq->cfqd; |
21183b07 | 543 | struct request *__alias; |
1da177e4 | 544 | |
5380a101 | 545 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
546 | |
547 | /* | |
548 | * looks a little odd, but the first insert might return an alias. | |
549 | * if that happens, put the alias on the dispatch list | |
550 | */ | |
21183b07 | 551 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 552 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
553 | |
554 | if (!cfq_cfqq_on_rr(cfqq)) | |
555 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
556 | |
557 | /* | |
558 | * check if this request is a better next-serve candidate | |
559 | */ | |
560 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); | |
561 | BUG_ON(!cfqq->next_rq); | |
1da177e4 LT |
562 | } |
563 | ||
564 | static inline void | |
5e705374 | 565 | cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 566 | { |
5380a101 JA |
567 | elv_rb_del(&cfqq->sort_list, rq); |
568 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 569 | cfq_add_rq_rb(rq); |
1da177e4 LT |
570 | } |
571 | ||
206dc69b JA |
572 | static struct request * |
573 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 574 | { |
206dc69b | 575 | struct task_struct *tsk = current; |
7749a8d4 | 576 | pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio), bio_sync(bio)); |
206dc69b | 577 | struct cfq_queue *cfqq; |
1da177e4 | 578 | |
206dc69b | 579 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); |
89850f7e JA |
580 | if (cfqq) { |
581 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
582 | ||
21183b07 | 583 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 584 | } |
1da177e4 | 585 | |
1da177e4 LT |
586 | return NULL; |
587 | } | |
588 | ||
b4878f24 | 589 | static void cfq_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 590 | { |
22e2c507 | 591 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 592 | |
b4878f24 | 593 | cfqd->rq_in_driver++; |
25776e35 JA |
594 | |
595 | /* | |
596 | * If the depth is larger 1, it really could be queueing. But lets | |
597 | * make the mark a little higher - idling could still be good for | |
598 | * low queueing, and a low queueing number could also just indicate | |
599 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
600 | */ | |
601 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
602 | cfqd->hw_tag = 1; | |
6d048f53 JA |
603 | |
604 | cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors; | |
1da177e4 LT |
605 | } |
606 | ||
b4878f24 | 607 | static void cfq_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 608 | { |
b4878f24 JA |
609 | struct cfq_data *cfqd = q->elevator->elevator_data; |
610 | ||
611 | WARN_ON(!cfqd->rq_in_driver); | |
612 | cfqd->rq_in_driver--; | |
1da177e4 LT |
613 | } |
614 | ||
b4878f24 | 615 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 616 | { |
5e705374 | 617 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 618 | |
5e705374 JA |
619 | if (cfqq->next_rq == rq) |
620 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 621 | |
b4878f24 | 622 | list_del_init(&rq->queuelist); |
5e705374 | 623 | cfq_del_rq_rb(rq); |
374f84ac JA |
624 | |
625 | if (rq_is_meta(rq)) { | |
626 | WARN_ON(!cfqq->meta_pending); | |
627 | cfqq->meta_pending--; | |
628 | } | |
1da177e4 LT |
629 | } |
630 | ||
631 | static int | |
632 | cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
633 | { | |
634 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
635 | struct request *__rq; | |
1da177e4 | 636 | |
206dc69b | 637 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 638 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
639 | *req = __rq; |
640 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
641 | } |
642 | ||
643 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
644 | } |
645 | ||
21183b07 JA |
646 | static void cfq_merged_request(request_queue_t *q, struct request *req, |
647 | int type) | |
1da177e4 | 648 | { |
21183b07 | 649 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 650 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 651 | |
5e705374 | 652 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 653 | } |
1da177e4 LT |
654 | } |
655 | ||
656 | static void | |
657 | cfq_merged_requests(request_queue_t *q, struct request *rq, | |
658 | struct request *next) | |
659 | { | |
22e2c507 JA |
660 | /* |
661 | * reposition in fifo if next is older than rq | |
662 | */ | |
663 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
664 | time_before(next->start_time, rq->start_time)) | |
665 | list_move(&rq->queuelist, &next->queuelist); | |
666 | ||
b4878f24 | 667 | cfq_remove_request(next); |
22e2c507 JA |
668 | } |
669 | ||
da775265 JA |
670 | static int cfq_allow_merge(request_queue_t *q, struct request *rq, |
671 | struct bio *bio) | |
672 | { | |
673 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
674 | const int rw = bio_data_dir(bio); | |
675 | struct cfq_queue *cfqq; | |
676 | pid_t key; | |
677 | ||
678 | /* | |
ec8acb69 | 679 | * Disallow merge of a sync bio into an async request. |
da775265 | 680 | */ |
ec8acb69 | 681 | if ((bio_data_dir(bio) == READ || bio_sync(bio)) && !rq_is_sync(rq)) |
da775265 JA |
682 | return 0; |
683 | ||
684 | /* | |
719d3402 JA |
685 | * Lookup the cfqq that this bio will be queued with. Allow |
686 | * merge only if rq is queued there. | |
da775265 | 687 | */ |
719d3402 | 688 | key = cfq_queue_pid(current, rw, bio_sync(bio)); |
da775265 | 689 | cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio); |
719d3402 JA |
690 | |
691 | if (cfqq == RQ_CFQQ(rq)) | |
692 | return 1; | |
da775265 | 693 | |
ec8acb69 | 694 | return 0; |
da775265 JA |
695 | } |
696 | ||
22e2c507 JA |
697 | static inline void |
698 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
699 | { | |
700 | if (cfqq) { | |
701 | /* | |
702 | * stop potential idle class queues waiting service | |
703 | */ | |
704 | del_timer(&cfqd->idle_class_timer); | |
705 | ||
22e2c507 | 706 | cfqq->slice_end = 0; |
3b18152c JA |
707 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
708 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 709 | cfq_mark_cfqq_slice_new(cfqq); |
1afba045 | 710 | cfq_clear_cfqq_queue_new(cfqq); |
22e2c507 JA |
711 | } |
712 | ||
713 | cfqd->active_queue = cfqq; | |
714 | } | |
715 | ||
7b14e3b5 JA |
716 | /* |
717 | * current cfqq expired its slice (or was too idle), select new one | |
718 | */ | |
719 | static void | |
720 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
3c6bd2f8 | 721 | int preempted, int timed_out) |
7b14e3b5 | 722 | { |
7b14e3b5 JA |
723 | if (cfq_cfqq_wait_request(cfqq)) |
724 | del_timer(&cfqd->idle_slice_timer); | |
725 | ||
7b14e3b5 JA |
726 | cfq_clear_cfqq_must_dispatch(cfqq); |
727 | cfq_clear_cfqq_wait_request(cfqq); | |
728 | ||
729 | /* | |
730 | * store what was left of this slice, if the queue idled out | |
731 | * or was preempted | |
732 | */ | |
3c6bd2f8 | 733 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) |
c5b680f3 | 734 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b14e3b5 | 735 | |
98e41c7d | 736 | cfq_resort_rr_list(cfqq, preempted); |
7b14e3b5 JA |
737 | |
738 | if (cfqq == cfqd->active_queue) | |
739 | cfqd->active_queue = NULL; | |
740 | ||
741 | if (cfqd->active_cic) { | |
742 | put_io_context(cfqd->active_cic->ioc); | |
743 | cfqd->active_cic = NULL; | |
744 | } | |
745 | ||
746 | cfqd->dispatch_slice = 0; | |
747 | } | |
748 | ||
3c6bd2f8 JA |
749 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted, |
750 | int timed_out) | |
7b14e3b5 JA |
751 | { |
752 | struct cfq_queue *cfqq = cfqd->active_queue; | |
753 | ||
754 | if (cfqq) | |
3c6bd2f8 | 755 | __cfq_slice_expired(cfqd, cfqq, preempted, timed_out); |
7b14e3b5 JA |
756 | } |
757 | ||
6d048f53 | 758 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 759 | { |
7b14e3b5 | 760 | struct cfq_queue *cfqq = NULL; |
22e2c507 | 761 | |
d9e7620e | 762 | if (!list_empty(&cfqd->cur_rr)) { |
89850f7e | 763 | /* |
d9e7620e | 764 | * if current list is non-empty, grab first entry. |
89850f7e | 765 | */ |
d9e7620e JA |
766 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); |
767 | } else if (!RB_EMPTY_ROOT(&cfqd->service_tree)) { | |
768 | struct rb_node *n = rb_first(&cfqd->service_tree); | |
769 | ||
770 | cfqq = rb_entry(n, struct cfq_queue, rb_node); | |
89850f7e JA |
771 | } else if (!list_empty(&cfqd->idle_rr)) { |
772 | /* | |
773 | * if we have idle queues and no rt or be queues had pending | |
774 | * requests, either allow immediate service if the grace period | |
775 | * has passed or arm the idle grace timer | |
776 | */ | |
22e2c507 JA |
777 | unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; |
778 | ||
779 | if (time_after_eq(jiffies, end)) | |
780 | cfqq = list_entry_cfqq(cfqd->idle_rr.next); | |
781 | else | |
782 | mod_timer(&cfqd->idle_class_timer, end); | |
783 | } | |
784 | ||
6d048f53 JA |
785 | return cfqq; |
786 | } | |
787 | ||
788 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) | |
789 | { | |
790 | struct cfq_queue *cfqq; | |
791 | ||
d9e7620e | 792 | cfqq = cfq_get_next_queue(cfqd); |
22e2c507 | 793 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 794 | return cfqq; |
22e2c507 JA |
795 | } |
796 | ||
d9e7620e JA |
797 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
798 | struct request *rq) | |
799 | { | |
800 | if (rq->sector >= cfqd->last_position) | |
801 | return rq->sector - cfqd->last_position; | |
802 | else | |
803 | return cfqd->last_position - rq->sector; | |
804 | } | |
805 | ||
6d048f53 JA |
806 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) |
807 | { | |
808 | struct cfq_io_context *cic = cfqd->active_cic; | |
809 | ||
810 | if (!sample_valid(cic->seek_samples)) | |
811 | return 0; | |
812 | ||
813 | return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean; | |
814 | } | |
815 | ||
d9e7620e JA |
816 | static int cfq_close_cooperator(struct cfq_data *cfq_data, |
817 | struct cfq_queue *cfqq) | |
6d048f53 | 818 | { |
6d048f53 | 819 | /* |
d9e7620e JA |
820 | * We should notice if some of the queues are cooperating, eg |
821 | * working closely on the same area of the disk. In that case, | |
822 | * we can group them together and don't waste time idling. | |
6d048f53 | 823 | */ |
d9e7620e | 824 | return 0; |
6d048f53 JA |
825 | } |
826 | ||
827 | #define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024)) | |
caaa5f9f | 828 | |
6d048f53 | 829 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 830 | { |
1792669c | 831 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 832 | struct cfq_io_context *cic; |
7b14e3b5 JA |
833 | unsigned long sl; |
834 | ||
dd67d051 | 835 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 836 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
837 | |
838 | /* | |
839 | * idle is disabled, either manually or by past process history | |
840 | */ | |
6d048f53 JA |
841 | if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
842 | return; | |
843 | ||
22e2c507 JA |
844 | /* |
845 | * task has exited, don't wait | |
846 | */ | |
206dc69b JA |
847 | cic = cfqd->active_cic; |
848 | if (!cic || !cic->ioc->task) | |
6d048f53 JA |
849 | return; |
850 | ||
851 | /* | |
852 | * See if this prio level has a good candidate | |
853 | */ | |
1afba045 JA |
854 | if (cfq_close_cooperator(cfqd, cfqq) && |
855 | (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2)) | |
6d048f53 | 856 | return; |
22e2c507 | 857 | |
3b18152c JA |
858 | cfq_mark_cfqq_must_dispatch(cfqq); |
859 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 860 | |
206dc69b JA |
861 | /* |
862 | * we don't want to idle for seeks, but we do want to allow | |
863 | * fair distribution of slice time for a process doing back-to-back | |
864 | * seeks. so allow a little bit of time for him to submit a new rq | |
865 | */ | |
6d048f53 | 866 | sl = cfqd->cfq_slice_idle; |
caaa5f9f | 867 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
d9e7620e | 868 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
206dc69b | 869 | |
7b14e3b5 | 870 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
1da177e4 LT |
871 | } |
872 | ||
5e705374 | 873 | static void cfq_dispatch_insert(request_queue_t *q, struct request *rq) |
1da177e4 | 874 | { |
5e705374 | 875 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 876 | |
5380a101 | 877 | cfq_remove_request(rq); |
6d048f53 | 878 | cfqq->dispatched++; |
5380a101 | 879 | elv_dispatch_sort(q, rq); |
1da177e4 LT |
880 | } |
881 | ||
882 | /* | |
883 | * return expired entry, or NULL to just start from scratch in rbtree | |
884 | */ | |
5e705374 | 885 | static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 LT |
886 | { |
887 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 888 | struct request *rq; |
89850f7e | 889 | int fifo; |
1da177e4 | 890 | |
3b18152c | 891 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 892 | return NULL; |
cb887411 JA |
893 | |
894 | cfq_mark_cfqq_fifo_expire(cfqq); | |
895 | ||
89850f7e JA |
896 | if (list_empty(&cfqq->fifo)) |
897 | return NULL; | |
1da177e4 | 898 | |
6d048f53 | 899 | fifo = cfq_cfqq_sync(cfqq); |
89850f7e | 900 | rq = rq_entry_fifo(cfqq->fifo.next); |
1da177e4 | 901 | |
6d048f53 JA |
902 | if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) |
903 | return NULL; | |
1da177e4 | 904 | |
6d048f53 | 905 | return rq; |
1da177e4 LT |
906 | } |
907 | ||
22e2c507 JA |
908 | static inline int |
909 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
910 | { | |
911 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 912 | |
22e2c507 | 913 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 914 | |
22e2c507 | 915 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
916 | } |
917 | ||
22e2c507 JA |
918 | /* |
919 | * get next queue for service | |
920 | */ | |
1b5ed5e1 | 921 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 922 | { |
1da177e4 | 923 | struct cfq_queue *cfqq; |
1da177e4 | 924 | |
22e2c507 JA |
925 | cfqq = cfqd->active_queue; |
926 | if (!cfqq) | |
927 | goto new_queue; | |
1da177e4 | 928 | |
22e2c507 | 929 | /* |
6d048f53 | 930 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 931 | */ |
6d048f53 | 932 | if (cfq_slice_used(cfqq)) |
3b18152c | 933 | goto expire; |
1da177e4 | 934 | |
22e2c507 | 935 | /* |
6d048f53 JA |
936 | * The active queue has requests and isn't expired, allow it to |
937 | * dispatch. | |
22e2c507 | 938 | */ |
dd67d051 | 939 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 940 | goto keep_queue; |
6d048f53 JA |
941 | |
942 | /* | |
943 | * No requests pending. If the active queue still has requests in | |
944 | * flight or is idling for a new request, allow either of these | |
945 | * conditions to happen (or time out) before selecting a new queue. | |
946 | */ | |
947 | if (cfqq->dispatched || timer_pending(&cfqd->idle_slice_timer)) { | |
caaa5f9f JA |
948 | cfqq = NULL; |
949 | goto keep_queue; | |
22e2c507 JA |
950 | } |
951 | ||
3b18152c | 952 | expire: |
3c6bd2f8 | 953 | cfq_slice_expired(cfqd, 0, 0); |
3b18152c JA |
954 | new_queue: |
955 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 956 | keep_queue: |
3b18152c | 957 | return cfqq; |
22e2c507 JA |
958 | } |
959 | ||
960 | static int | |
961 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
962 | int max_dispatch) | |
963 | { | |
964 | int dispatched = 0; | |
965 | ||
dd67d051 | 966 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
22e2c507 JA |
967 | |
968 | do { | |
5e705374 | 969 | struct request *rq; |
1da177e4 LT |
970 | |
971 | /* | |
22e2c507 | 972 | * follow expired path, else get first next available |
1da177e4 | 973 | */ |
5e705374 JA |
974 | if ((rq = cfq_check_fifo(cfqq)) == NULL) |
975 | rq = cfqq->next_rq; | |
22e2c507 JA |
976 | |
977 | /* | |
978 | * finally, insert request into driver dispatch list | |
979 | */ | |
5e705374 | 980 | cfq_dispatch_insert(cfqd->queue, rq); |
1da177e4 | 981 | |
22e2c507 JA |
982 | cfqd->dispatch_slice++; |
983 | dispatched++; | |
1da177e4 | 984 | |
22e2c507 | 985 | if (!cfqd->active_cic) { |
5e705374 JA |
986 | atomic_inc(&RQ_CIC(rq)->ioc->refcount); |
987 | cfqd->active_cic = RQ_CIC(rq); | |
22e2c507 | 988 | } |
1da177e4 | 989 | |
dd67d051 | 990 | if (RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 JA |
991 | break; |
992 | ||
993 | } while (dispatched < max_dispatch); | |
994 | ||
22e2c507 JA |
995 | /* |
996 | * expire an async queue immediately if it has used up its slice. idle | |
997 | * queue always expire after 1 dispatch round. | |
998 | */ | |
a9938006 | 999 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
22e2c507 | 1000 | cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
a9938006 | 1001 | cfq_class_idle(cfqq))) { |
44f7c160 | 1002 | cfqq->slice_end = jiffies + 1; |
3c6bd2f8 | 1003 | cfq_slice_expired(cfqd, 0, 0); |
44f7c160 | 1004 | } |
22e2c507 JA |
1005 | |
1006 | return dispatched; | |
1007 | } | |
1008 | ||
d9e7620e JA |
1009 | static inline int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
1010 | { | |
1011 | int dispatched = 0; | |
1012 | ||
1013 | while (cfqq->next_rq) { | |
1014 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1015 | dispatched++; | |
1016 | } | |
1017 | ||
1018 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1019 | return dispatched; | |
1020 | } | |
1021 | ||
1022 | static int cfq_forced_dispatch_cfqqs(struct list_head *list) | |
1b5ed5e1 | 1023 | { |
1b5ed5e1 | 1024 | struct cfq_queue *cfqq, *next; |
caaa5f9f | 1025 | int dispatched; |
1b5ed5e1 | 1026 | |
caaa5f9f | 1027 | dispatched = 0; |
d9e7620e JA |
1028 | list_for_each_entry_safe(cfqq, next, list, cfq_list) |
1029 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); | |
caaa5f9f | 1030 | |
1b5ed5e1 TH |
1031 | return dispatched; |
1032 | } | |
1033 | ||
d9e7620e | 1034 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1035 | { |
d9e7620e JA |
1036 | int dispatched = 0; |
1037 | struct rb_node *n; | |
1038 | ||
1039 | while ((n = rb_first(&cfqd->service_tree)) != NULL) { | |
1040 | struct cfq_queue *cfqq = rb_entry(n, struct cfq_queue, rb_node); | |
1b5ed5e1 | 1041 | |
d9e7620e JA |
1042 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1043 | } | |
1b5ed5e1 | 1044 | |
1b5ed5e1 TH |
1045 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr); |
1046 | dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr); | |
1047 | ||
3c6bd2f8 | 1048 | cfq_slice_expired(cfqd, 0, 0); |
1b5ed5e1 TH |
1049 | |
1050 | BUG_ON(cfqd->busy_queues); | |
1051 | ||
1052 | return dispatched; | |
1053 | } | |
1054 | ||
d9e7620e | 1055 | static int cfq_dispatch_requests(request_queue_t *q, int force) |
22e2c507 JA |
1056 | { |
1057 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
6d048f53 | 1058 | struct cfq_queue *cfqq; |
caaa5f9f | 1059 | int dispatched; |
22e2c507 JA |
1060 | |
1061 | if (!cfqd->busy_queues) | |
1062 | return 0; | |
1063 | ||
1b5ed5e1 TH |
1064 | if (unlikely(force)) |
1065 | return cfq_forced_dispatch(cfqd); | |
1066 | ||
caaa5f9f | 1067 | dispatched = 0; |
caaa5f9f | 1068 | while ((cfqq = cfq_select_queue(cfqd)) != NULL) { |
b4878f24 JA |
1069 | int max_dispatch; |
1070 | ||
a9938006 | 1071 | if (cfqd->busy_queues > 1) { |
a9938006 JA |
1072 | /* |
1073 | * So we have dispatched before in this round, if the | |
1074 | * next queue has idling enabled (must be sync), don't | |
6d048f53 | 1075 | * allow it service until the previous have completed. |
a9938006 | 1076 | */ |
6d048f53 JA |
1077 | if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq) && |
1078 | dispatched) | |
1079 | break; | |
1080 | if (cfqq->dispatched >= cfqd->cfq_quantum) | |
a9938006 JA |
1081 | break; |
1082 | } | |
9ede209e | 1083 | |
3b18152c JA |
1084 | cfq_clear_cfqq_must_dispatch(cfqq); |
1085 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1086 | del_timer(&cfqd->idle_slice_timer); |
1087 | ||
1b5ed5e1 TH |
1088 | max_dispatch = cfqd->cfq_quantum; |
1089 | if (cfq_class_idle(cfqq)) | |
1090 | max_dispatch = 1; | |
1da177e4 | 1091 | |
caaa5f9f | 1092 | dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1093 | } |
1094 | ||
caaa5f9f | 1095 | return dispatched; |
1da177e4 LT |
1096 | } |
1097 | ||
1da177e4 | 1098 | /* |
5e705374 JA |
1099 | * task holds one reference to the queue, dropped when task exits. each rq |
1100 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1101 | * |
1102 | * queue lock must be held here. | |
1103 | */ | |
1104 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1105 | { | |
22e2c507 JA |
1106 | struct cfq_data *cfqd = cfqq->cfqd; |
1107 | ||
1108 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1109 | |
1110 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1111 | return; | |
1112 | ||
1113 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1114 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1115 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1116 | |
28f95cbc | 1117 | if (unlikely(cfqd->active_queue == cfqq)) { |
3c6bd2f8 | 1118 | __cfq_slice_expired(cfqd, cfqq, 0, 0); |
28f95cbc JA |
1119 | cfq_schedule_dispatch(cfqd); |
1120 | } | |
22e2c507 | 1121 | |
1da177e4 LT |
1122 | /* |
1123 | * it's on the empty list and still hashed | |
1124 | */ | |
1da177e4 LT |
1125 | hlist_del(&cfqq->cfq_hash); |
1126 | kmem_cache_free(cfq_pool, cfqq); | |
1127 | } | |
1128 | ||
1ea25ecb | 1129 | static struct cfq_queue * |
3b18152c JA |
1130 | __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, |
1131 | const int hashval) | |
1da177e4 LT |
1132 | { |
1133 | struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; | |
206dc69b JA |
1134 | struct hlist_node *entry; |
1135 | struct cfq_queue *__cfqq; | |
1da177e4 | 1136 | |
206dc69b | 1137 | hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) { |
b0a6916b | 1138 | const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio); |
1da177e4 | 1139 | |
206dc69b | 1140 | if (__cfqq->key == key && (__p == prio || !prio)) |
1da177e4 LT |
1141 | return __cfqq; |
1142 | } | |
1143 | ||
1144 | return NULL; | |
1145 | } | |
1146 | ||
1147 | static struct cfq_queue * | |
3b18152c | 1148 | cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) |
1da177e4 | 1149 | { |
3b18152c | 1150 | return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); |
1da177e4 LT |
1151 | } |
1152 | ||
e2d74ac0 | 1153 | static void cfq_free_io_context(struct io_context *ioc) |
1da177e4 | 1154 | { |
22e2c507 | 1155 | struct cfq_io_context *__cic; |
e2d74ac0 JA |
1156 | struct rb_node *n; |
1157 | int freed = 0; | |
1da177e4 | 1158 | |
e2d74ac0 JA |
1159 | while ((n = rb_first(&ioc->cic_root)) != NULL) { |
1160 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1161 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
22e2c507 | 1162 | kmem_cache_free(cfq_ioc_pool, __cic); |
334e94de | 1163 | freed++; |
1da177e4 LT |
1164 | } |
1165 | ||
4050cf16 JA |
1166 | elv_ioc_count_mod(ioc_count, -freed); |
1167 | ||
1168 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) | |
334e94de | 1169 | complete(ioc_gone); |
1da177e4 LT |
1170 | } |
1171 | ||
89850f7e | 1172 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1173 | { |
28f95cbc | 1174 | if (unlikely(cfqq == cfqd->active_queue)) { |
3c6bd2f8 | 1175 | __cfq_slice_expired(cfqd, cfqq, 0, 0); |
28f95cbc JA |
1176 | cfq_schedule_dispatch(cfqd); |
1177 | } | |
22e2c507 | 1178 | |
89850f7e JA |
1179 | cfq_put_queue(cfqq); |
1180 | } | |
22e2c507 | 1181 | |
89850f7e JA |
1182 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1183 | struct cfq_io_context *cic) | |
1184 | { | |
fc46379d JA |
1185 | list_del_init(&cic->queue_list); |
1186 | smp_wmb(); | |
1187 | cic->key = NULL; | |
1188 | ||
12a05732 | 1189 | if (cic->cfqq[ASYNC]) { |
89850f7e | 1190 | cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]); |
12a05732 AV |
1191 | cic->cfqq[ASYNC] = NULL; |
1192 | } | |
1193 | ||
1194 | if (cic->cfqq[SYNC]) { | |
89850f7e | 1195 | cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]); |
12a05732 AV |
1196 | cic->cfqq[SYNC] = NULL; |
1197 | } | |
89850f7e JA |
1198 | } |
1199 | ||
1200 | ||
1201 | /* | |
1202 | * Called with interrupts disabled | |
1203 | */ | |
1204 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) | |
1205 | { | |
1206 | struct cfq_data *cfqd = cic->key; | |
1207 | ||
89850f7e JA |
1208 | if (cfqd) { |
1209 | request_queue_t *q = cfqd->queue; | |
1210 | ||
fc46379d | 1211 | spin_lock_irq(q->queue_lock); |
89850f7e | 1212 | __cfq_exit_single_io_context(cfqd, cic); |
fc46379d | 1213 | spin_unlock_irq(q->queue_lock); |
89850f7e | 1214 | } |
1da177e4 LT |
1215 | } |
1216 | ||
e2d74ac0 | 1217 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1218 | { |
22e2c507 | 1219 | struct cfq_io_context *__cic; |
e2d74ac0 | 1220 | struct rb_node *n; |
22e2c507 | 1221 | |
1da177e4 LT |
1222 | /* |
1223 | * put the reference this task is holding to the various queues | |
1224 | */ | |
e2d74ac0 JA |
1225 | |
1226 | n = rb_first(&ioc->cic_root); | |
1227 | while (n != NULL) { | |
1228 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1229 | ||
22e2c507 | 1230 | cfq_exit_single_io_context(__cic); |
e2d74ac0 | 1231 | n = rb_next(n); |
1da177e4 | 1232 | } |
1da177e4 LT |
1233 | } |
1234 | ||
22e2c507 | 1235 | static struct cfq_io_context * |
8267e268 | 1236 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1237 | { |
b5deef90 | 1238 | struct cfq_io_context *cic; |
1da177e4 | 1239 | |
b5deef90 | 1240 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask, cfqd->queue->node); |
1da177e4 | 1241 | if (cic) { |
553698f9 | 1242 | memset(cic, 0, sizeof(*cic)); |
22e2c507 | 1243 | cic->last_end_request = jiffies; |
553698f9 | 1244 | INIT_LIST_HEAD(&cic->queue_list); |
22e2c507 JA |
1245 | cic->dtor = cfq_free_io_context; |
1246 | cic->exit = cfq_exit_io_context; | |
4050cf16 | 1247 | elv_ioc_count_inc(ioc_count); |
1da177e4 LT |
1248 | } |
1249 | ||
1250 | return cic; | |
1251 | } | |
1252 | ||
22e2c507 JA |
1253 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1254 | { | |
1255 | struct task_struct *tsk = current; | |
1256 | int ioprio_class; | |
1257 | ||
3b18152c | 1258 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1259 | return; |
1260 | ||
1261 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1262 | switch (ioprio_class) { | |
1263 | default: | |
1264 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1265 | case IOPRIO_CLASS_NONE: | |
1266 | /* | |
1267 | * no prio set, place us in the middle of the BE classes | |
1268 | */ | |
1269 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1270 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1271 | break; | |
1272 | case IOPRIO_CLASS_RT: | |
1273 | cfqq->ioprio = task_ioprio(tsk); | |
1274 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1275 | break; | |
1276 | case IOPRIO_CLASS_BE: | |
1277 | cfqq->ioprio = task_ioprio(tsk); | |
1278 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1279 | break; | |
1280 | case IOPRIO_CLASS_IDLE: | |
1281 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1282 | cfqq->ioprio = 7; | |
3b18152c | 1283 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1284 | break; |
1285 | } | |
1286 | ||
1287 | /* | |
1288 | * keep track of original prio settings in case we have to temporarily | |
1289 | * elevate the priority of this queue | |
1290 | */ | |
1291 | cfqq->org_ioprio = cfqq->ioprio; | |
1292 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1293 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1294 | } |
1295 | ||
478a82b0 | 1296 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1297 | { |
478a82b0 AV |
1298 | struct cfq_data *cfqd = cic->key; |
1299 | struct cfq_queue *cfqq; | |
c1b707d2 | 1300 | unsigned long flags; |
35e6077c | 1301 | |
caaa5f9f JA |
1302 | if (unlikely(!cfqd)) |
1303 | return; | |
1304 | ||
c1b707d2 | 1305 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f JA |
1306 | |
1307 | cfqq = cic->cfqq[ASYNC]; | |
1308 | if (cfqq) { | |
1309 | struct cfq_queue *new_cfqq; | |
1310 | new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC, cic->ioc->task, | |
1311 | GFP_ATOMIC); | |
1312 | if (new_cfqq) { | |
1313 | cic->cfqq[ASYNC] = new_cfqq; | |
1314 | cfq_put_queue(cfqq); | |
1315 | } | |
22e2c507 | 1316 | } |
caaa5f9f JA |
1317 | |
1318 | cfqq = cic->cfqq[SYNC]; | |
1319 | if (cfqq) | |
1320 | cfq_mark_cfqq_prio_changed(cfqq); | |
1321 | ||
c1b707d2 | 1322 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
1323 | } |
1324 | ||
fc46379d | 1325 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 1326 | { |
a6a0763a | 1327 | struct cfq_io_context *cic; |
e2d74ac0 | 1328 | struct rb_node *n; |
a6a0763a | 1329 | |
fc46379d | 1330 | ioc->ioprio_changed = 0; |
a6a0763a | 1331 | |
e2d74ac0 JA |
1332 | n = rb_first(&ioc->cic_root); |
1333 | while (n != NULL) { | |
1334 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
3793c65c | 1335 | |
478a82b0 | 1336 | changed_ioprio(cic); |
e2d74ac0 JA |
1337 | n = rb_next(n); |
1338 | } | |
22e2c507 JA |
1339 | } |
1340 | ||
1341 | static struct cfq_queue * | |
6f325a13 | 1342 | cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, |
8267e268 | 1343 | gfp_t gfp_mask) |
22e2c507 JA |
1344 | { |
1345 | const int hashval = hash_long(key, CFQ_QHASH_SHIFT); | |
1346 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
6f325a13 | 1347 | unsigned short ioprio; |
22e2c507 JA |
1348 | |
1349 | retry: | |
6f325a13 | 1350 | ioprio = tsk->ioprio; |
3b18152c | 1351 | cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); |
22e2c507 JA |
1352 | |
1353 | if (!cfqq) { | |
1354 | if (new_cfqq) { | |
1355 | cfqq = new_cfqq; | |
1356 | new_cfqq = NULL; | |
1357 | } else if (gfp_mask & __GFP_WAIT) { | |
89850f7e JA |
1358 | /* |
1359 | * Inform the allocator of the fact that we will | |
1360 | * just repeat this allocation if it fails, to allow | |
1361 | * the allocator to do whatever it needs to attempt to | |
1362 | * free memory. | |
1363 | */ | |
22e2c507 | 1364 | spin_unlock_irq(cfqd->queue->queue_lock); |
b5deef90 | 1365 | new_cfqq = kmem_cache_alloc_node(cfq_pool, gfp_mask|__GFP_NOFAIL, cfqd->queue->node); |
22e2c507 JA |
1366 | spin_lock_irq(cfqd->queue->queue_lock); |
1367 | goto retry; | |
1368 | } else { | |
b5deef90 | 1369 | cfqq = kmem_cache_alloc_node(cfq_pool, gfp_mask, cfqd->queue->node); |
22e2c507 JA |
1370 | if (!cfqq) |
1371 | goto out; | |
1372 | } | |
1373 | ||
1374 | memset(cfqq, 0, sizeof(*cfqq)); | |
1375 | ||
1376 | INIT_HLIST_NODE(&cfqq->cfq_hash); | |
1377 | INIT_LIST_HEAD(&cfqq->cfq_list); | |
d9e7620e | 1378 | RB_CLEAR_NODE(&cfqq->rb_node); |
22e2c507 JA |
1379 | INIT_LIST_HEAD(&cfqq->fifo); |
1380 | ||
1381 | cfqq->key = key; | |
1382 | hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); | |
1383 | atomic_set(&cfqq->ref, 0); | |
1384 | cfqq->cfqd = cfqd; | |
c5b680f3 | 1385 | |
a9938006 JA |
1386 | if (key != CFQ_KEY_ASYNC) |
1387 | cfq_mark_cfqq_idle_window(cfqq); | |
1388 | ||
3b18152c | 1389 | cfq_mark_cfqq_prio_changed(cfqq); |
53b03744 | 1390 | cfq_mark_cfqq_queue_new(cfqq); |
3b18152c | 1391 | cfq_init_prio_data(cfqq); |
22e2c507 JA |
1392 | } |
1393 | ||
1394 | if (new_cfqq) | |
1395 | kmem_cache_free(cfq_pool, new_cfqq); | |
1396 | ||
1397 | atomic_inc(&cfqq->ref); | |
1398 | out: | |
1399 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1400 | return cfqq; | |
1401 | } | |
1402 | ||
dbecf3ab OH |
1403 | static void |
1404 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1405 | { | |
fc46379d | 1406 | WARN_ON(!list_empty(&cic->queue_list)); |
dbecf3ab | 1407 | rb_erase(&cic->rb_node, &ioc->cic_root); |
dbecf3ab | 1408 | kmem_cache_free(cfq_ioc_pool, cic); |
4050cf16 | 1409 | elv_ioc_count_dec(ioc_count); |
dbecf3ab OH |
1410 | } |
1411 | ||
e2d74ac0 JA |
1412 | static struct cfq_io_context * |
1413 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1414 | { | |
dbecf3ab | 1415 | struct rb_node *n; |
e2d74ac0 | 1416 | struct cfq_io_context *cic; |
be3b0753 | 1417 | void *k, *key = cfqd; |
e2d74ac0 | 1418 | |
dbecf3ab OH |
1419 | restart: |
1420 | n = ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1421 | while (n) { |
1422 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1423 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1424 | k = cic->key; | |
1425 | if (unlikely(!k)) { | |
dbecf3ab OH |
1426 | cfq_drop_dead_cic(ioc, cic); |
1427 | goto restart; | |
1428 | } | |
e2d74ac0 | 1429 | |
be3b0753 | 1430 | if (key < k) |
e2d74ac0 | 1431 | n = n->rb_left; |
be3b0753 | 1432 | else if (key > k) |
e2d74ac0 JA |
1433 | n = n->rb_right; |
1434 | else | |
1435 | return cic; | |
1436 | } | |
1437 | ||
1438 | return NULL; | |
1439 | } | |
1440 | ||
1441 | static inline void | |
1442 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1443 | struct cfq_io_context *cic) | |
1444 | { | |
dbecf3ab OH |
1445 | struct rb_node **p; |
1446 | struct rb_node *parent; | |
e2d74ac0 | 1447 | struct cfq_io_context *__cic; |
0261d688 | 1448 | unsigned long flags; |
be3b0753 | 1449 | void *k; |
e2d74ac0 | 1450 | |
e2d74ac0 JA |
1451 | cic->ioc = ioc; |
1452 | cic->key = cfqd; | |
1453 | ||
dbecf3ab OH |
1454 | restart: |
1455 | parent = NULL; | |
1456 | p = &ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1457 | while (*p) { |
1458 | parent = *p; | |
1459 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1460 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1461 | k = __cic->key; | |
1462 | if (unlikely(!k)) { | |
be33c3a6 | 1463 | cfq_drop_dead_cic(ioc, __cic); |
dbecf3ab OH |
1464 | goto restart; |
1465 | } | |
e2d74ac0 | 1466 | |
be3b0753 | 1467 | if (cic->key < k) |
e2d74ac0 | 1468 | p = &(*p)->rb_left; |
be3b0753 | 1469 | else if (cic->key > k) |
e2d74ac0 JA |
1470 | p = &(*p)->rb_right; |
1471 | else | |
1472 | BUG(); | |
1473 | } | |
1474 | ||
1475 | rb_link_node(&cic->rb_node, parent, p); | |
1476 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
fc46379d | 1477 | |
0261d688 | 1478 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
e2d74ac0 | 1479 | list_add(&cic->queue_list, &cfqd->cic_list); |
0261d688 | 1480 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
e2d74ac0 JA |
1481 | } |
1482 | ||
1da177e4 LT |
1483 | /* |
1484 | * Setup general io context and cfq io context. There can be several cfq | |
1485 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1486 | * than one device managed by cfq. |
1da177e4 LT |
1487 | */ |
1488 | static struct cfq_io_context * | |
e2d74ac0 | 1489 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1490 | { |
22e2c507 | 1491 | struct io_context *ioc = NULL; |
1da177e4 | 1492 | struct cfq_io_context *cic; |
1da177e4 | 1493 | |
22e2c507 | 1494 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1495 | |
b5deef90 | 1496 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
1497 | if (!ioc) |
1498 | return NULL; | |
1499 | ||
e2d74ac0 JA |
1500 | cic = cfq_cic_rb_lookup(cfqd, ioc); |
1501 | if (cic) | |
1502 | goto out; | |
1da177e4 | 1503 | |
e2d74ac0 JA |
1504 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1505 | if (cic == NULL) | |
1506 | goto err; | |
1da177e4 | 1507 | |
e2d74ac0 | 1508 | cfq_cic_link(cfqd, ioc, cic); |
1da177e4 | 1509 | out: |
fc46379d JA |
1510 | smp_read_barrier_depends(); |
1511 | if (unlikely(ioc->ioprio_changed)) | |
1512 | cfq_ioc_set_ioprio(ioc); | |
1513 | ||
1da177e4 LT |
1514 | return cic; |
1515 | err: | |
1516 | put_io_context(ioc); | |
1517 | return NULL; | |
1518 | } | |
1519 | ||
22e2c507 JA |
1520 | static void |
1521 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1522 | { |
aaf1228d JA |
1523 | unsigned long elapsed = jiffies - cic->last_end_request; |
1524 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 1525 | |
22e2c507 JA |
1526 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1527 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1528 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1529 | } | |
1da177e4 | 1530 | |
206dc69b | 1531 | static void |
6d048f53 JA |
1532 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, |
1533 | struct request *rq) | |
206dc69b JA |
1534 | { |
1535 | sector_t sdist; | |
1536 | u64 total; | |
1537 | ||
5e705374 JA |
1538 | if (cic->last_request_pos < rq->sector) |
1539 | sdist = rq->sector - cic->last_request_pos; | |
206dc69b | 1540 | else |
5e705374 | 1541 | sdist = cic->last_request_pos - rq->sector; |
206dc69b | 1542 | |
6d048f53 JA |
1543 | if (!cic->seek_samples) { |
1544 | cfqd->new_seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1545 | cfqd->new_seek_mean = cfqd->new_seek_total / 256; | |
1546 | } | |
1547 | ||
206dc69b JA |
1548 | /* |
1549 | * Don't allow the seek distance to get too large from the | |
1550 | * odd fragment, pagein, etc | |
1551 | */ | |
1552 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1553 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1554 | else | |
1555 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1556 | ||
1557 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1558 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1559 | total = cic->seek_total + (cic->seek_samples/2); | |
1560 | do_div(total, cic->seek_samples); | |
1561 | cic->seek_mean = (sector_t)total; | |
1562 | } | |
1da177e4 | 1563 | |
22e2c507 JA |
1564 | /* |
1565 | * Disable idle window if the process thinks too long or seeks so much that | |
1566 | * it doesn't matter | |
1567 | */ | |
1568 | static void | |
1569 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1570 | struct cfq_io_context *cic) | |
1571 | { | |
3b18152c | 1572 | int enable_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1573 | |
caaa5f9f JA |
1574 | if (!cic->ioc->task || !cfqd->cfq_slice_idle || |
1575 | (cfqd->hw_tag && CIC_SEEKY(cic))) | |
22e2c507 JA |
1576 | enable_idle = 0; |
1577 | else if (sample_valid(cic->ttime_samples)) { | |
1578 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1579 | enable_idle = 0; | |
1580 | else | |
1581 | enable_idle = 1; | |
1da177e4 LT |
1582 | } |
1583 | ||
3b18152c JA |
1584 | if (enable_idle) |
1585 | cfq_mark_cfqq_idle_window(cfqq); | |
1586 | else | |
1587 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1588 | } |
1da177e4 | 1589 | |
22e2c507 JA |
1590 | /* |
1591 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1592 | * no or if we aren't sure, a 1 will cause a preempt. | |
1593 | */ | |
1594 | static int | |
1595 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
5e705374 | 1596 | struct request *rq) |
22e2c507 | 1597 | { |
6d048f53 | 1598 | struct cfq_queue *cfqq; |
22e2c507 | 1599 | |
6d048f53 JA |
1600 | cfqq = cfqd->active_queue; |
1601 | if (!cfqq) | |
22e2c507 JA |
1602 | return 0; |
1603 | ||
6d048f53 JA |
1604 | if (cfq_slice_used(cfqq)) |
1605 | return 1; | |
1606 | ||
1607 | if (cfq_class_idle(new_cfqq)) | |
caaa5f9f | 1608 | return 0; |
22e2c507 JA |
1609 | |
1610 | if (cfq_class_idle(cfqq)) | |
1611 | return 1; | |
1e3335de | 1612 | |
374f84ac JA |
1613 | /* |
1614 | * if the new request is sync, but the currently running queue is | |
1615 | * not, let the sync request have priority. | |
1616 | */ | |
5e705374 | 1617 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 | 1618 | return 1; |
1e3335de | 1619 | |
374f84ac JA |
1620 | /* |
1621 | * So both queues are sync. Let the new request get disk time if | |
1622 | * it's a metadata request and the current queue is doing regular IO. | |
1623 | */ | |
1624 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
1625 | return 1; | |
22e2c507 | 1626 | |
1e3335de JA |
1627 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
1628 | return 0; | |
1629 | ||
1630 | /* | |
1631 | * if this request is as-good as one we would expect from the | |
1632 | * current cfqq, let it preempt | |
1633 | */ | |
6d048f53 | 1634 | if (cfq_rq_close(cfqd, rq)) |
1e3335de JA |
1635 | return 1; |
1636 | ||
22e2c507 JA |
1637 | return 0; |
1638 | } | |
1639 | ||
1640 | /* | |
1641 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1642 | * let it have half of its nominal slice. | |
1643 | */ | |
1644 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1645 | { | |
3c6bd2f8 | 1646 | cfq_slice_expired(cfqd, 1, 1); |
22e2c507 | 1647 | |
bf572256 JA |
1648 | /* |
1649 | * Put the new queue at the front of the of the current list, | |
1650 | * so we know that it will be selected next. | |
1651 | */ | |
1652 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
d9e7620e JA |
1653 | list_del_init(&cfqq->cfq_list); |
1654 | list_add(&cfqq->cfq_list, &cfqd->cur_rr); | |
bf572256 | 1655 | |
44f7c160 JA |
1656 | cfqq->slice_end = 0; |
1657 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
1658 | } |
1659 | ||
22e2c507 | 1660 | /* |
5e705374 | 1661 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
1662 | * something we should do about it |
1663 | */ | |
1664 | static void | |
5e705374 JA |
1665 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1666 | struct request *rq) | |
22e2c507 | 1667 | { |
5e705374 | 1668 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 1669 | |
374f84ac JA |
1670 | if (rq_is_meta(rq)) |
1671 | cfqq->meta_pending++; | |
1672 | ||
9c2c38a1 | 1673 | cfq_update_io_thinktime(cfqd, cic); |
6d048f53 | 1674 | cfq_update_io_seektime(cfqd, cic, rq); |
9c2c38a1 JA |
1675 | cfq_update_idle_window(cfqd, cfqq, cic); |
1676 | ||
5e705374 | 1677 | cic->last_request_pos = rq->sector + rq->nr_sectors; |
6d048f53 | 1678 | cfqq->last_request_pos = cic->last_request_pos; |
22e2c507 JA |
1679 | |
1680 | if (cfqq == cfqd->active_queue) { | |
1681 | /* | |
1682 | * if we are waiting for a request for this queue, let it rip | |
1683 | * immediately and flag that we must not expire this queue | |
1684 | * just now | |
1685 | */ | |
3b18152c JA |
1686 | if (cfq_cfqq_wait_request(cfqq)) { |
1687 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 | 1688 | del_timer(&cfqd->idle_slice_timer); |
dc72ef4a | 1689 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1690 | } |
5e705374 | 1691 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
1692 | /* |
1693 | * not the active queue - expire current slice if it is | |
1694 | * idle and has expired it's mean thinktime or this new queue | |
1695 | * has some old slice time left and is of higher priority | |
1696 | */ | |
1697 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1698 | cfq_mark_cfqq_must_dispatch(cfqq); |
dc72ef4a | 1699 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1700 | } |
1da177e4 LT |
1701 | } |
1702 | ||
b4878f24 | 1703 | static void cfq_insert_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1704 | { |
b4878f24 | 1705 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1706 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 JA |
1707 | |
1708 | cfq_init_prio_data(cfqq); | |
1da177e4 | 1709 | |
5e705374 | 1710 | cfq_add_rq_rb(rq); |
1da177e4 | 1711 | |
22e2c507 JA |
1712 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1713 | ||
5e705374 | 1714 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
1715 | } |
1716 | ||
1da177e4 LT |
1717 | static void cfq_completed_request(request_queue_t *q, struct request *rq) |
1718 | { | |
5e705374 | 1719 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 1720 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 1721 | const int sync = rq_is_sync(rq); |
b4878f24 | 1722 | unsigned long now; |
1da177e4 | 1723 | |
b4878f24 | 1724 | now = jiffies; |
1da177e4 | 1725 | |
b4878f24 | 1726 | WARN_ON(!cfqd->rq_in_driver); |
6d048f53 | 1727 | WARN_ON(!cfqq->dispatched); |
b4878f24 | 1728 | cfqd->rq_in_driver--; |
6d048f53 | 1729 | cfqq->dispatched--; |
1da177e4 | 1730 | |
b4878f24 JA |
1731 | if (!cfq_class_idle(cfqq)) |
1732 | cfqd->last_end_request = now; | |
3b18152c | 1733 | |
caaa5f9f | 1734 | if (sync) |
5e705374 | 1735 | RQ_CIC(rq)->last_end_request = now; |
caaa5f9f JA |
1736 | |
1737 | /* | |
1738 | * If this is the active queue, check if it needs to be expired, | |
1739 | * or if we want to idle in case it has no pending requests. | |
1740 | */ | |
1741 | if (cfqd->active_queue == cfqq) { | |
44f7c160 JA |
1742 | if (cfq_cfqq_slice_new(cfqq)) { |
1743 | cfq_set_prio_slice(cfqd, cfqq); | |
1744 | cfq_clear_cfqq_slice_new(cfqq); | |
1745 | } | |
1746 | if (cfq_slice_used(cfqq)) | |
3c6bd2f8 | 1747 | cfq_slice_expired(cfqd, 0, 1); |
6d048f53 JA |
1748 | else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) |
1749 | cfq_arm_slice_timer(cfqd); | |
caaa5f9f | 1750 | } |
6d048f53 JA |
1751 | |
1752 | if (!cfqd->rq_in_driver) | |
1753 | cfq_schedule_dispatch(cfqd); | |
1da177e4 LT |
1754 | } |
1755 | ||
22e2c507 JA |
1756 | /* |
1757 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1758 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1759 | */ | |
1760 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1761 | { |
22e2c507 JA |
1762 | if (has_fs_excl()) { |
1763 | /* | |
1764 | * boost idle prio on transactions that would lock out other | |
1765 | * users of the filesystem | |
1766 | */ | |
1767 | if (cfq_class_idle(cfqq)) | |
1768 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1769 | if (cfqq->ioprio > IOPRIO_NORM) | |
1770 | cfqq->ioprio = IOPRIO_NORM; | |
1771 | } else { | |
1772 | /* | |
1773 | * check if we need to unboost the queue | |
1774 | */ | |
1775 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1776 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1777 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1778 | cfqq->ioprio = cfqq->org_ioprio; | |
1779 | } | |
22e2c507 | 1780 | } |
1da177e4 | 1781 | |
89850f7e | 1782 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 1783 | { |
3b18152c | 1784 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && |
99f95e52 | 1785 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1786 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1787 | return ELV_MQUEUE_MUST; |
3b18152c | 1788 | } |
1da177e4 | 1789 | |
22e2c507 | 1790 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
1791 | } |
1792 | ||
cb78b285 | 1793 | static int cfq_may_queue(request_queue_t *q, int rw) |
22e2c507 JA |
1794 | { |
1795 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1796 | struct task_struct *tsk = current; | |
1797 | struct cfq_queue *cfqq; | |
7749a8d4 JA |
1798 | unsigned int key; |
1799 | ||
1800 | key = cfq_queue_pid(tsk, rw, rw & REQ_RW_SYNC); | |
22e2c507 JA |
1801 | |
1802 | /* | |
1803 | * don't force setup of a queue from here, as a call to may_queue | |
1804 | * does not necessarily imply that a request actually will be queued. | |
1805 | * so just lookup a possibly existing queue, or return 'may queue' | |
1806 | * if that fails | |
1807 | */ | |
7749a8d4 | 1808 | cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio); |
22e2c507 JA |
1809 | if (cfqq) { |
1810 | cfq_init_prio_data(cfqq); | |
1811 | cfq_prio_boost(cfqq); | |
1812 | ||
89850f7e | 1813 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
1814 | } |
1815 | ||
1816 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1817 | } |
1818 | ||
1da177e4 LT |
1819 | /* |
1820 | * queue lock held here | |
1821 | */ | |
bb37b94c | 1822 | static void cfq_put_request(struct request *rq) |
1da177e4 | 1823 | { |
5e705374 | 1824 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 1825 | |
5e705374 | 1826 | if (cfqq) { |
22e2c507 | 1827 | const int rw = rq_data_dir(rq); |
1da177e4 | 1828 | |
22e2c507 JA |
1829 | BUG_ON(!cfqq->allocated[rw]); |
1830 | cfqq->allocated[rw]--; | |
1da177e4 | 1831 | |
5e705374 | 1832 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 1833 | |
1da177e4 | 1834 | rq->elevator_private = NULL; |
5e705374 | 1835 | rq->elevator_private2 = NULL; |
1da177e4 | 1836 | |
1da177e4 LT |
1837 | cfq_put_queue(cfqq); |
1838 | } | |
1839 | } | |
1840 | ||
1841 | /* | |
22e2c507 | 1842 | * Allocate cfq data structures associated with this request. |
1da177e4 | 1843 | */ |
22e2c507 | 1844 | static int |
cb78b285 | 1845 | cfq_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
1846 | { |
1847 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 1848 | struct task_struct *tsk = current; |
1da177e4 LT |
1849 | struct cfq_io_context *cic; |
1850 | const int rw = rq_data_dir(rq); | |
7749a8d4 JA |
1851 | const int is_sync = rq_is_sync(rq); |
1852 | pid_t key = cfq_queue_pid(tsk, rw, is_sync); | |
22e2c507 | 1853 | struct cfq_queue *cfqq; |
1da177e4 LT |
1854 | unsigned long flags; |
1855 | ||
1856 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1857 | ||
e2d74ac0 | 1858 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 1859 | |
1da177e4 LT |
1860 | spin_lock_irqsave(q->queue_lock, flags); |
1861 | ||
22e2c507 JA |
1862 | if (!cic) |
1863 | goto queue_fail; | |
1864 | ||
12a05732 | 1865 | if (!cic->cfqq[is_sync]) { |
6f325a13 | 1866 | cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask); |
22e2c507 JA |
1867 | if (!cfqq) |
1868 | goto queue_fail; | |
1da177e4 | 1869 | |
12a05732 | 1870 | cic->cfqq[is_sync] = cfqq; |
22e2c507 | 1871 | } else |
12a05732 | 1872 | cfqq = cic->cfqq[is_sync]; |
1da177e4 LT |
1873 | |
1874 | cfqq->allocated[rw]++; | |
3b18152c | 1875 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 | 1876 | atomic_inc(&cfqq->ref); |
1da177e4 | 1877 | |
5e705374 | 1878 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 1879 | |
5e705374 JA |
1880 | rq->elevator_private = cic; |
1881 | rq->elevator_private2 = cfqq; | |
1882 | return 0; | |
1da177e4 | 1883 | |
22e2c507 JA |
1884 | queue_fail: |
1885 | if (cic) | |
1886 | put_io_context(cic->ioc); | |
89850f7e | 1887 | |
3b18152c | 1888 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1889 | spin_unlock_irqrestore(q->queue_lock, flags); |
1890 | return 1; | |
1891 | } | |
1892 | ||
65f27f38 | 1893 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 1894 | { |
65f27f38 DH |
1895 | struct cfq_data *cfqd = |
1896 | container_of(work, struct cfq_data, unplug_work); | |
1897 | request_queue_t *q = cfqd->queue; | |
22e2c507 JA |
1898 | unsigned long flags; |
1899 | ||
1900 | spin_lock_irqsave(q->queue_lock, flags); | |
dc72ef4a | 1901 | blk_start_queueing(q); |
22e2c507 JA |
1902 | spin_unlock_irqrestore(q->queue_lock, flags); |
1903 | } | |
1904 | ||
1905 | /* | |
1906 | * Timer running if the active_queue is currently idling inside its time slice | |
1907 | */ | |
1908 | static void cfq_idle_slice_timer(unsigned long data) | |
1909 | { | |
1910 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
1911 | struct cfq_queue *cfqq; | |
1912 | unsigned long flags; | |
3c6bd2f8 | 1913 | int timed_out = 1; |
22e2c507 JA |
1914 | |
1915 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1916 | ||
1917 | if ((cfqq = cfqd->active_queue) != NULL) { | |
3c6bd2f8 JA |
1918 | timed_out = 0; |
1919 | ||
22e2c507 JA |
1920 | /* |
1921 | * expired | |
1922 | */ | |
44f7c160 | 1923 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
1924 | goto expire; |
1925 | ||
1926 | /* | |
1927 | * only expire and reinvoke request handler, if there are | |
1928 | * other queues with pending requests | |
1929 | */ | |
caaa5f9f | 1930 | if (!cfqd->busy_queues) |
22e2c507 | 1931 | goto out_cont; |
22e2c507 JA |
1932 | |
1933 | /* | |
1934 | * not expired and it has a request pending, let it dispatch | |
1935 | */ | |
dd67d051 | 1936 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) { |
3b18152c | 1937 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
1938 | goto out_kick; |
1939 | } | |
1940 | } | |
1941 | expire: | |
3c6bd2f8 | 1942 | cfq_slice_expired(cfqd, 0, timed_out); |
22e2c507 | 1943 | out_kick: |
3b18152c | 1944 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
1945 | out_cont: |
1946 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1947 | } | |
1948 | ||
1949 | /* | |
1950 | * Timer running if an idle class queue is waiting for service | |
1951 | */ | |
1952 | static void cfq_idle_class_timer(unsigned long data) | |
1953 | { | |
1954 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
1955 | unsigned long flags, end; | |
1956 | ||
1957 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1958 | ||
1959 | /* | |
1960 | * race with a non-idle queue, reset timer | |
1961 | */ | |
1962 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
ae818a38 JA |
1963 | if (!time_after_eq(jiffies, end)) |
1964 | mod_timer(&cfqd->idle_class_timer, end); | |
1965 | else | |
3b18152c | 1966 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
1967 | |
1968 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1969 | } | |
1970 | ||
3b18152c JA |
1971 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
1972 | { | |
1973 | del_timer_sync(&cfqd->idle_slice_timer); | |
1974 | del_timer_sync(&cfqd->idle_class_timer); | |
1975 | blk_sync_queue(cfqd->queue); | |
1976 | } | |
22e2c507 | 1977 | |
1da177e4 LT |
1978 | static void cfq_exit_queue(elevator_t *e) |
1979 | { | |
22e2c507 | 1980 | struct cfq_data *cfqd = e->elevator_data; |
d9ff4187 | 1981 | request_queue_t *q = cfqd->queue; |
22e2c507 | 1982 | |
3b18152c | 1983 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 1984 | |
d9ff4187 | 1985 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 1986 | |
d9ff4187 | 1987 | if (cfqd->active_queue) |
3c6bd2f8 | 1988 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0, 0); |
e2d74ac0 JA |
1989 | |
1990 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
1991 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
1992 | struct cfq_io_context, | |
1993 | queue_list); | |
89850f7e JA |
1994 | |
1995 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 1996 | } |
e2d74ac0 | 1997 | |
d9ff4187 | 1998 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
1999 | |
2000 | cfq_shutdown_timer_wq(cfqd); | |
2001 | ||
a90d742e AV |
2002 | kfree(cfqd->cfq_hash); |
2003 | kfree(cfqd); | |
1da177e4 LT |
2004 | } |
2005 | ||
bb37b94c | 2006 | static void *cfq_init_queue(request_queue_t *q) |
1da177e4 LT |
2007 | { |
2008 | struct cfq_data *cfqd; | |
2009 | int i; | |
2010 | ||
b5deef90 | 2011 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node); |
1da177e4 | 2012 | if (!cfqd) |
bc1c1169 | 2013 | return NULL; |
1da177e4 LT |
2014 | |
2015 | memset(cfqd, 0, sizeof(*cfqd)); | |
22e2c507 | 2016 | |
d9e7620e | 2017 | cfqd->service_tree = RB_ROOT; |
22e2c507 JA |
2018 | INIT_LIST_HEAD(&cfqd->cur_rr); |
2019 | INIT_LIST_HEAD(&cfqd->idle_rr); | |
d9ff4187 | 2020 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2021 | |
b5deef90 | 2022 | cfqd->cfq_hash = kmalloc_node(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL, q->node); |
1da177e4 | 2023 | if (!cfqd->cfq_hash) |
5e705374 | 2024 | goto out_free; |
1da177e4 | 2025 | |
1da177e4 LT |
2026 | for (i = 0; i < CFQ_QHASH_ENTRIES; i++) |
2027 | INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); | |
2028 | ||
1da177e4 | 2029 | cfqd->queue = q; |
1da177e4 | 2030 | |
22e2c507 JA |
2031 | init_timer(&cfqd->idle_slice_timer); |
2032 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2033 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2034 | ||
2035 | init_timer(&cfqd->idle_class_timer); | |
2036 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2037 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2038 | ||
65f27f38 | 2039 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2040 | |
1da177e4 | 2041 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2042 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2043 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2044 | cfqd->cfq_back_max = cfq_back_max; |
2045 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2046 | cfqd->cfq_slice[0] = cfq_slice_async; |
2047 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2048 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2049 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2050 | |
bc1c1169 | 2051 | return cfqd; |
5e705374 | 2052 | out_free: |
1da177e4 | 2053 | kfree(cfqd); |
bc1c1169 | 2054 | return NULL; |
1da177e4 LT |
2055 | } |
2056 | ||
2057 | static void cfq_slab_kill(void) | |
2058 | { | |
1da177e4 LT |
2059 | if (cfq_pool) |
2060 | kmem_cache_destroy(cfq_pool); | |
2061 | if (cfq_ioc_pool) | |
2062 | kmem_cache_destroy(cfq_ioc_pool); | |
2063 | } | |
2064 | ||
2065 | static int __init cfq_slab_setup(void) | |
2066 | { | |
1da177e4 LT |
2067 | cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, |
2068 | NULL, NULL); | |
2069 | if (!cfq_pool) | |
2070 | goto fail; | |
2071 | ||
2072 | cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", | |
2073 | sizeof(struct cfq_io_context), 0, 0, NULL, NULL); | |
2074 | if (!cfq_ioc_pool) | |
2075 | goto fail; | |
2076 | ||
2077 | return 0; | |
2078 | fail: | |
2079 | cfq_slab_kill(); | |
2080 | return -ENOMEM; | |
2081 | } | |
2082 | ||
1da177e4 LT |
2083 | /* |
2084 | * sysfs parts below --> | |
2085 | */ | |
1da177e4 LT |
2086 | static ssize_t |
2087 | cfq_var_show(unsigned int var, char *page) | |
2088 | { | |
2089 | return sprintf(page, "%d\n", var); | |
2090 | } | |
2091 | ||
2092 | static ssize_t | |
2093 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2094 | { | |
2095 | char *p = (char *) page; | |
2096 | ||
2097 | *var = simple_strtoul(p, &p, 10); | |
2098 | return count; | |
2099 | } | |
2100 | ||
1da177e4 | 2101 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2102 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2103 | { \ |
3d1ab40f | 2104 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2105 | unsigned int __data = __VAR; \ |
2106 | if (__CONV) \ | |
2107 | __data = jiffies_to_msecs(__data); \ | |
2108 | return cfq_var_show(__data, (page)); \ | |
2109 | } | |
2110 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
2111 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2112 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2113 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2114 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2115 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2116 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2117 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2118 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2119 | #undef SHOW_FUNCTION |
2120 | ||
2121 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2122 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2123 | { \ |
3d1ab40f | 2124 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2125 | unsigned int __data; \ |
2126 | int ret = cfq_var_store(&__data, (page), count); \ | |
2127 | if (__data < (MIN)) \ | |
2128 | __data = (MIN); \ | |
2129 | else if (__data > (MAX)) \ | |
2130 | __data = (MAX); \ | |
2131 | if (__CONV) \ | |
2132 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2133 | else \ | |
2134 | *(__PTR) = __data; \ | |
2135 | return ret; \ | |
2136 | } | |
2137 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
22e2c507 JA |
2138 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2139 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2140 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2141 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2142 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2143 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2144 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2145 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2146 | #undef STORE_FUNCTION |
2147 | ||
e572ec7e AV |
2148 | #define CFQ_ATTR(name) \ |
2149 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2150 | ||
2151 | static struct elv_fs_entry cfq_attrs[] = { | |
2152 | CFQ_ATTR(quantum), | |
e572ec7e AV |
2153 | CFQ_ATTR(fifo_expire_sync), |
2154 | CFQ_ATTR(fifo_expire_async), | |
2155 | CFQ_ATTR(back_seek_max), | |
2156 | CFQ_ATTR(back_seek_penalty), | |
2157 | CFQ_ATTR(slice_sync), | |
2158 | CFQ_ATTR(slice_async), | |
2159 | CFQ_ATTR(slice_async_rq), | |
2160 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2161 | __ATTR_NULL |
1da177e4 LT |
2162 | }; |
2163 | ||
1da177e4 LT |
2164 | static struct elevator_type iosched_cfq = { |
2165 | .ops = { | |
2166 | .elevator_merge_fn = cfq_merge, | |
2167 | .elevator_merged_fn = cfq_merged_request, | |
2168 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 2169 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 2170 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2171 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2172 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2173 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2174 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2175 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
2176 | .elevator_former_req_fn = elv_rb_former_request, |
2177 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
2178 | .elevator_set_req_fn = cfq_set_request, |
2179 | .elevator_put_req_fn = cfq_put_request, | |
2180 | .elevator_may_queue_fn = cfq_may_queue, | |
2181 | .elevator_init_fn = cfq_init_queue, | |
2182 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 2183 | .trim = cfq_free_io_context, |
1da177e4 | 2184 | }, |
3d1ab40f | 2185 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2186 | .elevator_name = "cfq", |
2187 | .elevator_owner = THIS_MODULE, | |
2188 | }; | |
2189 | ||
2190 | static int __init cfq_init(void) | |
2191 | { | |
2192 | int ret; | |
2193 | ||
22e2c507 JA |
2194 | /* |
2195 | * could be 0 on HZ < 1000 setups | |
2196 | */ | |
2197 | if (!cfq_slice_async) | |
2198 | cfq_slice_async = 1; | |
2199 | if (!cfq_slice_idle) | |
2200 | cfq_slice_idle = 1; | |
2201 | ||
1da177e4 LT |
2202 | if (cfq_slab_setup()) |
2203 | return -ENOMEM; | |
2204 | ||
2205 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2206 | if (ret) |
2207 | cfq_slab_kill(); | |
1da177e4 | 2208 | |
1da177e4 LT |
2209 | return ret; |
2210 | } | |
2211 | ||
2212 | static void __exit cfq_exit(void) | |
2213 | { | |
6e9a4738 | 2214 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 2215 | elv_unregister(&iosched_cfq); |
334e94de | 2216 | ioc_gone = &all_gone; |
fba82272 OH |
2217 | /* ioc_gone's update must be visible before reading ioc_count */ |
2218 | smp_wmb(); | |
4050cf16 | 2219 | if (elv_ioc_count_read(ioc_count)) |
fba82272 | 2220 | wait_for_completion(ioc_gone); |
334e94de | 2221 | synchronize_rcu(); |
83521d3e | 2222 | cfq_slab_kill(); |
1da177e4 LT |
2223 | } |
2224 | ||
2225 | module_init(cfq_init); | |
2226 | module_exit(cfq_exit); | |
2227 | ||
2228 | MODULE_AUTHOR("Jens Axboe"); | |
2229 | MODULE_LICENSE("GPL"); | |
2230 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |