Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * CFQ, or complete fairness queueing, disk scheduler. |
3 | * | |
4 | * Based on ideas from a previously unfinished io | |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
6 | * | |
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 | 12 | #include <linux/rbtree.h> |
22e2c507 | 13 | #include <linux/ioprio.h> |
1da177e4 LT |
14 | |
15 | /* | |
16 | * tunables | |
17 | */ | |
64100099 | 18 | static const int cfq_quantum = 4; /* max queue in one round of service */ |
64100099 AV |
19 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
20 | static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ | |
21 | static const int cfq_back_penalty = 2; /* penalty of a backwards seek */ | |
1da177e4 | 22 | |
64100099 | 23 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 24 | static int cfq_slice_async = HZ / 25; |
64100099 | 25 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 26 | static int cfq_slice_idle = HZ / 125; |
22e2c507 | 27 | |
d9e7620e JA |
28 | /* |
29 | * grace period before allowing idle class to get disk access | |
30 | */ | |
22e2c507 | 31 | #define CFQ_IDLE_GRACE (HZ / 10) |
d9e7620e JA |
32 | |
33 | /* | |
34 | * below this threshold, we consider thinktime immediate | |
35 | */ | |
36 | #define CFQ_MIN_TT (2) | |
37 | ||
22e2c507 JA |
38 | #define CFQ_SLICE_SCALE (5) |
39 | ||
5e705374 JA |
40 | #define RQ_CIC(rq) ((struct cfq_io_context*)(rq)->elevator_private) |
41 | #define RQ_CFQQ(rq) ((rq)->elevator_private2) | |
1da177e4 | 42 | |
e18b890b CL |
43 | static struct kmem_cache *cfq_pool; |
44 | static struct kmem_cache *cfq_ioc_pool; | |
1da177e4 | 45 | |
4050cf16 | 46 | static DEFINE_PER_CPU(unsigned long, ioc_count); |
334e94de AV |
47 | static struct completion *ioc_gone; |
48 | ||
22e2c507 JA |
49 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
50 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
22e2c507 JA |
51 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
52 | ||
3b18152c JA |
53 | #define ASYNC (0) |
54 | #define SYNC (1) | |
55 | ||
206dc69b JA |
56 | #define sample_valid(samples) ((samples) > 80) |
57 | ||
cc09e299 JA |
58 | /* |
59 | * Most of our rbtree usage is for sorting with min extraction, so | |
60 | * if we cache the leftmost node we don't have to walk down the tree | |
61 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should | |
62 | * move this into the elevator for the rq sorting as well. | |
63 | */ | |
64 | struct cfq_rb_root { | |
65 | struct rb_root rb; | |
66 | struct rb_node *left; | |
67 | }; | |
68 | #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, } | |
69 | ||
22e2c507 JA |
70 | /* |
71 | * Per block device queue structure | |
72 | */ | |
1da177e4 | 73 | struct cfq_data { |
165125e1 | 74 | struct request_queue *queue; |
22e2c507 JA |
75 | |
76 | /* | |
77 | * rr list of queues with requests and the count of them | |
78 | */ | |
cc09e299 | 79 | struct cfq_rb_root service_tree; |
22e2c507 JA |
80 | unsigned int busy_queues; |
81 | ||
22e2c507 | 82 | int rq_in_driver; |
3ed9a296 | 83 | int sync_flight; |
25776e35 | 84 | int hw_tag; |
1da177e4 | 85 | |
22e2c507 JA |
86 | /* |
87 | * idle window management | |
88 | */ | |
89 | struct timer_list idle_slice_timer; | |
90 | struct work_struct unplug_work; | |
1da177e4 | 91 | |
22e2c507 JA |
92 | struct cfq_queue *active_queue; |
93 | struct cfq_io_context *active_cic; | |
22e2c507 | 94 | |
c2dea2d1 VT |
95 | /* |
96 | * async queue for each priority case | |
97 | */ | |
98 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
99 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 100 | |
22e2c507 | 101 | struct timer_list idle_class_timer; |
1da177e4 | 102 | |
6d048f53 | 103 | sector_t last_position; |
22e2c507 | 104 | unsigned long last_end_request; |
1da177e4 | 105 | |
1da177e4 LT |
106 | /* |
107 | * tunables, see top of file | |
108 | */ | |
109 | unsigned int cfq_quantum; | |
22e2c507 | 110 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
111 | unsigned int cfq_back_penalty; |
112 | unsigned int cfq_back_max; | |
22e2c507 JA |
113 | unsigned int cfq_slice[2]; |
114 | unsigned int cfq_slice_async_rq; | |
115 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
116 | |
117 | struct list_head cic_list; | |
1da177e4 LT |
118 | }; |
119 | ||
22e2c507 JA |
120 | /* |
121 | * Per process-grouping structure | |
122 | */ | |
1da177e4 LT |
123 | struct cfq_queue { |
124 | /* reference count */ | |
125 | atomic_t ref; | |
126 | /* parent cfq_data */ | |
127 | struct cfq_data *cfqd; | |
d9e7620e JA |
128 | /* service_tree member */ |
129 | struct rb_node rb_node; | |
130 | /* service_tree key */ | |
131 | unsigned long rb_key; | |
1da177e4 LT |
132 | /* sorted list of pending requests */ |
133 | struct rb_root sort_list; | |
134 | /* if fifo isn't expired, next request to serve */ | |
5e705374 | 135 | struct request *next_rq; |
1da177e4 LT |
136 | /* requests queued in sort_list */ |
137 | int queued[2]; | |
138 | /* currently allocated requests */ | |
139 | int allocated[2]; | |
374f84ac JA |
140 | /* pending metadata requests */ |
141 | int meta_pending; | |
1da177e4 | 142 | /* fifo list of requests in sort_list */ |
22e2c507 | 143 | struct list_head fifo; |
1da177e4 | 144 | |
22e2c507 | 145 | unsigned long slice_end; |
c5b680f3 | 146 | long slice_resid; |
1da177e4 | 147 | |
6d048f53 JA |
148 | /* number of requests that are on the dispatch list or inside driver */ |
149 | int dispatched; | |
22e2c507 JA |
150 | |
151 | /* io prio of this group */ | |
152 | unsigned short ioprio, org_ioprio; | |
153 | unsigned short ioprio_class, org_ioprio_class; | |
154 | ||
3b18152c JA |
155 | /* various state flags, see below */ |
156 | unsigned int flags; | |
1da177e4 LT |
157 | }; |
158 | ||
3b18152c | 159 | enum cfqq_state_flags { |
b0b8d749 JA |
160 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
161 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
162 | CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ | |
163 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ | |
164 | CFQ_CFQQ_FLAG_must_dispatch, /* must dispatch, even if expired */ | |
165 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ | |
166 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
167 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
168 | CFQ_CFQQ_FLAG_queue_new, /* queue never been serviced */ | |
44f7c160 | 169 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 170 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
3b18152c JA |
171 | }; |
172 | ||
173 | #define CFQ_CFQQ_FNS(name) \ | |
174 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
175 | { \ | |
176 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
177 | } \ | |
178 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
179 | { \ | |
180 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
181 | } \ | |
182 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
183 | { \ | |
184 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
185 | } | |
186 | ||
187 | CFQ_CFQQ_FNS(on_rr); | |
188 | CFQ_CFQQ_FNS(wait_request); | |
189 | CFQ_CFQQ_FNS(must_alloc); | |
190 | CFQ_CFQQ_FNS(must_alloc_slice); | |
191 | CFQ_CFQQ_FNS(must_dispatch); | |
192 | CFQ_CFQQ_FNS(fifo_expire); | |
193 | CFQ_CFQQ_FNS(idle_window); | |
194 | CFQ_CFQQ_FNS(prio_changed); | |
53b03744 | 195 | CFQ_CFQQ_FNS(queue_new); |
44f7c160 | 196 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 197 | CFQ_CFQQ_FNS(sync); |
3b18152c JA |
198 | #undef CFQ_CFQQ_FNS |
199 | ||
165125e1 | 200 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
91fac317 VT |
201 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, int, |
202 | struct task_struct *, gfp_t); | |
203 | static struct cfq_io_context *cfq_cic_rb_lookup(struct cfq_data *, | |
204 | struct io_context *); | |
205 | ||
206 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, | |
207 | int is_sync) | |
208 | { | |
209 | return cic->cfqq[!!is_sync]; | |
210 | } | |
211 | ||
212 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
213 | struct cfq_queue *cfqq, int is_sync) | |
214 | { | |
215 | cic->cfqq[!!is_sync] = cfqq; | |
216 | } | |
217 | ||
218 | /* | |
219 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
220 | * set (in which case it could also be direct WRITE). | |
221 | */ | |
222 | static inline int cfq_bio_sync(struct bio *bio) | |
223 | { | |
224 | if (bio_data_dir(bio) == READ || bio_sync(bio)) | |
225 | return 1; | |
226 | ||
227 | return 0; | |
228 | } | |
1da177e4 | 229 | |
99f95e52 AM |
230 | /* |
231 | * scheduler run of queue, if there are requests pending and no one in the | |
232 | * driver that will restart queueing | |
233 | */ | |
234 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
235 | { | |
7b14e3b5 | 236 | if (cfqd->busy_queues) |
99f95e52 AM |
237 | kblockd_schedule_work(&cfqd->unplug_work); |
238 | } | |
239 | ||
165125e1 | 240 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
241 | { |
242 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
243 | ||
b4878f24 | 244 | return !cfqd->busy_queues; |
99f95e52 AM |
245 | } |
246 | ||
44f7c160 JA |
247 | /* |
248 | * Scale schedule slice based on io priority. Use the sync time slice only | |
249 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
250 | * io only, should not get full sync slice length. | |
251 | */ | |
d9e7620e JA |
252 | static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync, |
253 | unsigned short prio) | |
44f7c160 | 254 | { |
d9e7620e | 255 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 256 | |
d9e7620e JA |
257 | WARN_ON(prio >= IOPRIO_BE_NR); |
258 | ||
259 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
260 | } | |
44f7c160 | 261 | |
d9e7620e JA |
262 | static inline int |
263 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
264 | { | |
265 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
266 | } |
267 | ||
268 | static inline void | |
269 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
270 | { | |
271 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
272 | } | |
273 | ||
274 | /* | |
275 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
276 | * isn't valid until the first request from the dispatch is activated | |
277 | * and the slice time set. | |
278 | */ | |
279 | static inline int cfq_slice_used(struct cfq_queue *cfqq) | |
280 | { | |
281 | if (cfq_cfqq_slice_new(cfqq)) | |
282 | return 0; | |
283 | if (time_before(jiffies, cfqq->slice_end)) | |
284 | return 0; | |
285 | ||
286 | return 1; | |
287 | } | |
288 | ||
1da177e4 | 289 | /* |
5e705374 | 290 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 291 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 292 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 293 | */ |
5e705374 JA |
294 | static struct request * |
295 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
1da177e4 LT |
296 | { |
297 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 298 | unsigned long back_max; |
e8a99053 AM |
299 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
300 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
301 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 302 | |
5e705374 JA |
303 | if (rq1 == NULL || rq1 == rq2) |
304 | return rq2; | |
305 | if (rq2 == NULL) | |
306 | return rq1; | |
9c2c38a1 | 307 | |
5e705374 JA |
308 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
309 | return rq1; | |
310 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
311 | return rq2; | |
374f84ac JA |
312 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
313 | return rq1; | |
314 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
315 | return rq2; | |
1da177e4 | 316 | |
5e705374 JA |
317 | s1 = rq1->sector; |
318 | s2 = rq2->sector; | |
1da177e4 | 319 | |
6d048f53 | 320 | last = cfqd->last_position; |
1da177e4 | 321 | |
1da177e4 LT |
322 | /* |
323 | * by definition, 1KiB is 2 sectors | |
324 | */ | |
325 | back_max = cfqd->cfq_back_max * 2; | |
326 | ||
327 | /* | |
328 | * Strict one way elevator _except_ in the case where we allow | |
329 | * short backward seeks which are biased as twice the cost of a | |
330 | * similar forward seek. | |
331 | */ | |
332 | if (s1 >= last) | |
333 | d1 = s1 - last; | |
334 | else if (s1 + back_max >= last) | |
335 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
336 | else | |
e8a99053 | 337 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
338 | |
339 | if (s2 >= last) | |
340 | d2 = s2 - last; | |
341 | else if (s2 + back_max >= last) | |
342 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
343 | else | |
e8a99053 | 344 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
345 | |
346 | /* Found required data */ | |
e8a99053 AM |
347 | |
348 | /* | |
349 | * By doing switch() on the bit mask "wrap" we avoid having to | |
350 | * check two variables for all permutations: --> faster! | |
351 | */ | |
352 | switch (wrap) { | |
5e705374 | 353 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 354 | if (d1 < d2) |
5e705374 | 355 | return rq1; |
e8a99053 | 356 | else if (d2 < d1) |
5e705374 | 357 | return rq2; |
e8a99053 AM |
358 | else { |
359 | if (s1 >= s2) | |
5e705374 | 360 | return rq1; |
e8a99053 | 361 | else |
5e705374 | 362 | return rq2; |
e8a99053 | 363 | } |
1da177e4 | 364 | |
e8a99053 | 365 | case CFQ_RQ2_WRAP: |
5e705374 | 366 | return rq1; |
e8a99053 | 367 | case CFQ_RQ1_WRAP: |
5e705374 JA |
368 | return rq2; |
369 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
370 | default: |
371 | /* | |
372 | * Since both rqs are wrapped, | |
373 | * start with the one that's further behind head | |
374 | * (--> only *one* back seek required), | |
375 | * since back seek takes more time than forward. | |
376 | */ | |
377 | if (s1 <= s2) | |
5e705374 | 378 | return rq1; |
1da177e4 | 379 | else |
5e705374 | 380 | return rq2; |
1da177e4 LT |
381 | } |
382 | } | |
383 | ||
498d3aa2 JA |
384 | /* |
385 | * The below is leftmost cache rbtree addon | |
386 | */ | |
cc09e299 JA |
387 | static struct rb_node *cfq_rb_first(struct cfq_rb_root *root) |
388 | { | |
389 | if (!root->left) | |
390 | root->left = rb_first(&root->rb); | |
391 | ||
392 | return root->left; | |
393 | } | |
394 | ||
395 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) | |
396 | { | |
397 | if (root->left == n) | |
398 | root->left = NULL; | |
399 | ||
400 | rb_erase(n, &root->rb); | |
401 | RB_CLEAR_NODE(n); | |
402 | } | |
403 | ||
1da177e4 LT |
404 | /* |
405 | * would be nice to take fifo expire time into account as well | |
406 | */ | |
5e705374 JA |
407 | static struct request * |
408 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
409 | struct request *last) | |
1da177e4 | 410 | { |
21183b07 JA |
411 | struct rb_node *rbnext = rb_next(&last->rb_node); |
412 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 413 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 414 | |
21183b07 | 415 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
416 | |
417 | if (rbprev) | |
5e705374 | 418 | prev = rb_entry_rq(rbprev); |
1da177e4 | 419 | |
21183b07 | 420 | if (rbnext) |
5e705374 | 421 | next = rb_entry_rq(rbnext); |
21183b07 JA |
422 | else { |
423 | rbnext = rb_first(&cfqq->sort_list); | |
424 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 425 | next = rb_entry_rq(rbnext); |
21183b07 | 426 | } |
1da177e4 | 427 | |
21183b07 | 428 | return cfq_choose_req(cfqd, next, prev); |
1da177e4 LT |
429 | } |
430 | ||
d9e7620e JA |
431 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
432 | struct cfq_queue *cfqq) | |
1da177e4 | 433 | { |
d9e7620e JA |
434 | /* |
435 | * just an approximation, should be ok. | |
436 | */ | |
67e6b49e JA |
437 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
438 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
439 | } |
440 | ||
498d3aa2 JA |
441 | /* |
442 | * The cfqd->service_tree holds all pending cfq_queue's that have | |
443 | * requests waiting to be processed. It is sorted in the order that | |
444 | * we will service the queues. | |
445 | */ | |
d9e7620e | 446 | static void cfq_service_tree_add(struct cfq_data *cfqd, |
edd75ffd | 447 | struct cfq_queue *cfqq, int add_front) |
d9e7620e | 448 | { |
cc09e299 | 449 | struct rb_node **p = &cfqd->service_tree.rb.rb_node; |
d9e7620e | 450 | struct rb_node *parent = NULL; |
d9e7620e | 451 | unsigned long rb_key; |
498d3aa2 | 452 | int left; |
d9e7620e | 453 | |
edd75ffd JA |
454 | if (!add_front) { |
455 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; | |
456 | rb_key += cfqq->slice_resid; | |
457 | cfqq->slice_resid = 0; | |
458 | } else | |
459 | rb_key = 0; | |
1da177e4 | 460 | |
d9e7620e | 461 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 462 | /* |
d9e7620e | 463 | * same position, nothing more to do |
99f9628a | 464 | */ |
d9e7620e JA |
465 | if (rb_key == cfqq->rb_key) |
466 | return; | |
1da177e4 | 467 | |
cc09e299 | 468 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
1da177e4 | 469 | } |
d9e7620e | 470 | |
498d3aa2 | 471 | left = 1; |
d9e7620e | 472 | while (*p) { |
cc09e299 | 473 | struct cfq_queue *__cfqq; |
67060e37 | 474 | struct rb_node **n; |
cc09e299 | 475 | |
d9e7620e JA |
476 | parent = *p; |
477 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
478 | ||
0c534e0a JA |
479 | /* |
480 | * sort RT queues first, we always want to give | |
67060e37 JA |
481 | * preference to them. IDLE queues goes to the back. |
482 | * after that, sort on the next service time. | |
0c534e0a JA |
483 | */ |
484 | if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) | |
67060e37 | 485 | n = &(*p)->rb_left; |
0c534e0a | 486 | else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) |
67060e37 JA |
487 | n = &(*p)->rb_right; |
488 | else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) | |
489 | n = &(*p)->rb_left; | |
490 | else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) | |
491 | n = &(*p)->rb_right; | |
0c534e0a | 492 | else if (rb_key < __cfqq->rb_key) |
67060e37 JA |
493 | n = &(*p)->rb_left; |
494 | else | |
495 | n = &(*p)->rb_right; | |
496 | ||
497 | if (n == &(*p)->rb_right) | |
cc09e299 | 498 | left = 0; |
67060e37 JA |
499 | |
500 | p = n; | |
d9e7620e JA |
501 | } |
502 | ||
cc09e299 JA |
503 | if (left) |
504 | cfqd->service_tree.left = &cfqq->rb_node; | |
505 | ||
d9e7620e JA |
506 | cfqq->rb_key = rb_key; |
507 | rb_link_node(&cfqq->rb_node, parent, p); | |
cc09e299 | 508 | rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); |
1da177e4 LT |
509 | } |
510 | ||
498d3aa2 JA |
511 | /* |
512 | * Update cfqq's position in the service tree. | |
513 | */ | |
edd75ffd | 514 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 515 | { |
6d048f53 JA |
516 | /* |
517 | * Resorting requires the cfqq to be on the RR list already. | |
518 | */ | |
498d3aa2 | 519 | if (cfq_cfqq_on_rr(cfqq)) |
edd75ffd | 520 | cfq_service_tree_add(cfqd, cfqq, 0); |
6d048f53 JA |
521 | } |
522 | ||
1da177e4 LT |
523 | /* |
524 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 525 | * the pending list according to last request service |
1da177e4 LT |
526 | */ |
527 | static inline void | |
b4878f24 | 528 | cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 529 | { |
3b18152c JA |
530 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
531 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
532 | cfqd->busy_queues++; |
533 | ||
edd75ffd | 534 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
535 | } |
536 | ||
498d3aa2 JA |
537 | /* |
538 | * Called when the cfqq no longer has requests pending, remove it from | |
539 | * the service tree. | |
540 | */ | |
1da177e4 LT |
541 | static inline void |
542 | cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
543 | { | |
3b18152c JA |
544 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
545 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 546 | |
cc09e299 JA |
547 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) |
548 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); | |
d9e7620e | 549 | |
1da177e4 LT |
550 | BUG_ON(!cfqd->busy_queues); |
551 | cfqd->busy_queues--; | |
552 | } | |
553 | ||
554 | /* | |
555 | * rb tree support functions | |
556 | */ | |
5e705374 | 557 | static inline void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 558 | { |
5e705374 | 559 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 560 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 561 | const int sync = rq_is_sync(rq); |
1da177e4 | 562 | |
b4878f24 JA |
563 | BUG_ON(!cfqq->queued[sync]); |
564 | cfqq->queued[sync]--; | |
1da177e4 | 565 | |
5e705374 | 566 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 567 | |
dd67d051 | 568 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 569 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
570 | } |
571 | ||
5e705374 | 572 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 573 | { |
5e705374 | 574 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 575 | struct cfq_data *cfqd = cfqq->cfqd; |
21183b07 | 576 | struct request *__alias; |
1da177e4 | 577 | |
5380a101 | 578 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
579 | |
580 | /* | |
581 | * looks a little odd, but the first insert might return an alias. | |
582 | * if that happens, put the alias on the dispatch list | |
583 | */ | |
21183b07 | 584 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 585 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
586 | |
587 | if (!cfq_cfqq_on_rr(cfqq)) | |
588 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
589 | |
590 | /* | |
591 | * check if this request is a better next-serve candidate | |
592 | */ | |
593 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); | |
594 | BUG_ON(!cfqq->next_rq); | |
1da177e4 LT |
595 | } |
596 | ||
597 | static inline void | |
5e705374 | 598 | cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 599 | { |
5380a101 JA |
600 | elv_rb_del(&cfqq->sort_list, rq); |
601 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 602 | cfq_add_rq_rb(rq); |
1da177e4 LT |
603 | } |
604 | ||
206dc69b JA |
605 | static struct request * |
606 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 607 | { |
206dc69b | 608 | struct task_struct *tsk = current; |
91fac317 | 609 | struct cfq_io_context *cic; |
206dc69b | 610 | struct cfq_queue *cfqq; |
1da177e4 | 611 | |
91fac317 VT |
612 | cic = cfq_cic_rb_lookup(cfqd, tsk->io_context); |
613 | if (!cic) | |
614 | return NULL; | |
615 | ||
616 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
617 | if (cfqq) { |
618 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
619 | ||
21183b07 | 620 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 621 | } |
1da177e4 | 622 | |
1da177e4 LT |
623 | return NULL; |
624 | } | |
625 | ||
165125e1 | 626 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 627 | { |
22e2c507 | 628 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 629 | |
b4878f24 | 630 | cfqd->rq_in_driver++; |
25776e35 JA |
631 | |
632 | /* | |
633 | * If the depth is larger 1, it really could be queueing. But lets | |
634 | * make the mark a little higher - idling could still be good for | |
635 | * low queueing, and a low queueing number could also just indicate | |
636 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
637 | */ | |
638 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
639 | cfqd->hw_tag = 1; | |
6d048f53 JA |
640 | |
641 | cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors; | |
1da177e4 LT |
642 | } |
643 | ||
165125e1 | 644 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 645 | { |
b4878f24 JA |
646 | struct cfq_data *cfqd = q->elevator->elevator_data; |
647 | ||
648 | WARN_ON(!cfqd->rq_in_driver); | |
649 | cfqd->rq_in_driver--; | |
1da177e4 LT |
650 | } |
651 | ||
b4878f24 | 652 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 653 | { |
5e705374 | 654 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 655 | |
5e705374 JA |
656 | if (cfqq->next_rq == rq) |
657 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 658 | |
b4878f24 | 659 | list_del_init(&rq->queuelist); |
5e705374 | 660 | cfq_del_rq_rb(rq); |
374f84ac JA |
661 | |
662 | if (rq_is_meta(rq)) { | |
663 | WARN_ON(!cfqq->meta_pending); | |
664 | cfqq->meta_pending--; | |
665 | } | |
1da177e4 LT |
666 | } |
667 | ||
165125e1 JA |
668 | static int cfq_merge(struct request_queue *q, struct request **req, |
669 | struct bio *bio) | |
1da177e4 LT |
670 | { |
671 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
672 | struct request *__rq; | |
1da177e4 | 673 | |
206dc69b | 674 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 675 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
676 | *req = __rq; |
677 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
678 | } |
679 | ||
680 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
681 | } |
682 | ||
165125e1 | 683 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 684 | int type) |
1da177e4 | 685 | { |
21183b07 | 686 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 687 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 688 | |
5e705374 | 689 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 690 | } |
1da177e4 LT |
691 | } |
692 | ||
693 | static void | |
165125e1 | 694 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
695 | struct request *next) |
696 | { | |
22e2c507 JA |
697 | /* |
698 | * reposition in fifo if next is older than rq | |
699 | */ | |
700 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
701 | time_before(next->start_time, rq->start_time)) | |
702 | list_move(&rq->queuelist, &next->queuelist); | |
703 | ||
b4878f24 | 704 | cfq_remove_request(next); |
22e2c507 JA |
705 | } |
706 | ||
165125e1 | 707 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
708 | struct bio *bio) |
709 | { | |
710 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 711 | struct cfq_io_context *cic; |
da775265 | 712 | struct cfq_queue *cfqq; |
da775265 JA |
713 | |
714 | /* | |
ec8acb69 | 715 | * Disallow merge of a sync bio into an async request. |
da775265 | 716 | */ |
91fac317 | 717 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
da775265 JA |
718 | return 0; |
719 | ||
720 | /* | |
719d3402 JA |
721 | * Lookup the cfqq that this bio will be queued with. Allow |
722 | * merge only if rq is queued there. | |
da775265 | 723 | */ |
91fac317 VT |
724 | cic = cfq_cic_rb_lookup(cfqd, current->io_context); |
725 | if (!cic) | |
726 | return 0; | |
719d3402 | 727 | |
91fac317 | 728 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
719d3402 JA |
729 | if (cfqq == RQ_CFQQ(rq)) |
730 | return 1; | |
da775265 | 731 | |
ec8acb69 | 732 | return 0; |
da775265 JA |
733 | } |
734 | ||
22e2c507 JA |
735 | static inline void |
736 | __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
737 | { | |
738 | if (cfqq) { | |
739 | /* | |
740 | * stop potential idle class queues waiting service | |
741 | */ | |
742 | del_timer(&cfqd->idle_class_timer); | |
743 | ||
22e2c507 | 744 | cfqq->slice_end = 0; |
3b18152c JA |
745 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
746 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 747 | cfq_mark_cfqq_slice_new(cfqq); |
1afba045 | 748 | cfq_clear_cfqq_queue_new(cfqq); |
22e2c507 JA |
749 | } |
750 | ||
751 | cfqd->active_queue = cfqq; | |
752 | } | |
753 | ||
7b14e3b5 JA |
754 | /* |
755 | * current cfqq expired its slice (or was too idle), select new one | |
756 | */ | |
757 | static void | |
758 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
6084cdda | 759 | int timed_out) |
7b14e3b5 | 760 | { |
7b14e3b5 JA |
761 | if (cfq_cfqq_wait_request(cfqq)) |
762 | del_timer(&cfqd->idle_slice_timer); | |
763 | ||
7b14e3b5 JA |
764 | cfq_clear_cfqq_must_dispatch(cfqq); |
765 | cfq_clear_cfqq_wait_request(cfqq); | |
766 | ||
767 | /* | |
6084cdda | 768 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 769 | */ |
3c6bd2f8 | 770 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) |
c5b680f3 | 771 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b14e3b5 | 772 | |
edd75ffd | 773 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
774 | |
775 | if (cfqq == cfqd->active_queue) | |
776 | cfqd->active_queue = NULL; | |
777 | ||
778 | if (cfqd->active_cic) { | |
779 | put_io_context(cfqd->active_cic->ioc); | |
780 | cfqd->active_cic = NULL; | |
781 | } | |
7b14e3b5 JA |
782 | } |
783 | ||
6084cdda | 784 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out) |
7b14e3b5 JA |
785 | { |
786 | struct cfq_queue *cfqq = cfqd->active_queue; | |
787 | ||
788 | if (cfqq) | |
6084cdda | 789 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
790 | } |
791 | ||
498d3aa2 JA |
792 | /* |
793 | * Get next queue for service. Unless we have a queue preemption, | |
794 | * we'll simply select the first cfqq in the service tree. | |
795 | */ | |
6d048f53 | 796 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 797 | { |
edd75ffd JA |
798 | struct cfq_queue *cfqq; |
799 | struct rb_node *n; | |
22e2c507 | 800 | |
edd75ffd JA |
801 | if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) |
802 | return NULL; | |
d9e7620e | 803 | |
edd75ffd JA |
804 | n = cfq_rb_first(&cfqd->service_tree); |
805 | cfqq = rb_entry(n, struct cfq_queue, rb_node); | |
498d3aa2 | 806 | |
edd75ffd JA |
807 | if (cfq_class_idle(cfqq)) { |
808 | unsigned long end; | |
809 | ||
810 | /* | |
811 | * if we have idle queues and no rt or be queues had | |
812 | * pending requests, either allow immediate service if | |
813 | * the grace period has passed or arm the idle grace | |
814 | * timer | |
815 | */ | |
816 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
817 | if (time_before(jiffies, end)) { | |
818 | mod_timer(&cfqd->idle_class_timer, end); | |
819 | cfqq = NULL; | |
67060e37 | 820 | } |
22e2c507 JA |
821 | } |
822 | ||
6d048f53 JA |
823 | return cfqq; |
824 | } | |
825 | ||
498d3aa2 JA |
826 | /* |
827 | * Get and set a new active queue for service. | |
828 | */ | |
6d048f53 JA |
829 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
830 | { | |
831 | struct cfq_queue *cfqq; | |
832 | ||
d9e7620e | 833 | cfqq = cfq_get_next_queue(cfqd); |
22e2c507 | 834 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 835 | return cfqq; |
22e2c507 JA |
836 | } |
837 | ||
d9e7620e JA |
838 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
839 | struct request *rq) | |
840 | { | |
841 | if (rq->sector >= cfqd->last_position) | |
842 | return rq->sector - cfqd->last_position; | |
843 | else | |
844 | return cfqd->last_position - rq->sector; | |
845 | } | |
846 | ||
6d048f53 JA |
847 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) |
848 | { | |
849 | struct cfq_io_context *cic = cfqd->active_cic; | |
850 | ||
851 | if (!sample_valid(cic->seek_samples)) | |
852 | return 0; | |
853 | ||
854 | return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean; | |
855 | } | |
856 | ||
d9e7620e JA |
857 | static int cfq_close_cooperator(struct cfq_data *cfq_data, |
858 | struct cfq_queue *cfqq) | |
6d048f53 | 859 | { |
6d048f53 | 860 | /* |
d9e7620e JA |
861 | * We should notice if some of the queues are cooperating, eg |
862 | * working closely on the same area of the disk. In that case, | |
863 | * we can group them together and don't waste time idling. | |
6d048f53 | 864 | */ |
d9e7620e | 865 | return 0; |
6d048f53 JA |
866 | } |
867 | ||
868 | #define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024)) | |
caaa5f9f | 869 | |
6d048f53 | 870 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 871 | { |
1792669c | 872 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 873 | struct cfq_io_context *cic; |
7b14e3b5 JA |
874 | unsigned long sl; |
875 | ||
dd67d051 | 876 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 877 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
878 | |
879 | /* | |
880 | * idle is disabled, either manually or by past process history | |
881 | */ | |
6d048f53 JA |
882 | if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
883 | return; | |
884 | ||
22e2c507 JA |
885 | /* |
886 | * task has exited, don't wait | |
887 | */ | |
206dc69b JA |
888 | cic = cfqd->active_cic; |
889 | if (!cic || !cic->ioc->task) | |
6d048f53 JA |
890 | return; |
891 | ||
892 | /* | |
893 | * See if this prio level has a good candidate | |
894 | */ | |
1afba045 JA |
895 | if (cfq_close_cooperator(cfqd, cfqq) && |
896 | (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2)) | |
6d048f53 | 897 | return; |
22e2c507 | 898 | |
3b18152c JA |
899 | cfq_mark_cfqq_must_dispatch(cfqq); |
900 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 901 | |
206dc69b JA |
902 | /* |
903 | * we don't want to idle for seeks, but we do want to allow | |
904 | * fair distribution of slice time for a process doing back-to-back | |
905 | * seeks. so allow a little bit of time for him to submit a new rq | |
906 | */ | |
6d048f53 | 907 | sl = cfqd->cfq_slice_idle; |
caaa5f9f | 908 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
d9e7620e | 909 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
206dc69b | 910 | |
7b14e3b5 | 911 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
1da177e4 LT |
912 | } |
913 | ||
498d3aa2 JA |
914 | /* |
915 | * Move request from internal lists to the request queue dispatch list. | |
916 | */ | |
165125e1 | 917 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 918 | { |
3ed9a296 | 919 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 920 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 921 | |
5380a101 | 922 | cfq_remove_request(rq); |
6d048f53 | 923 | cfqq->dispatched++; |
5380a101 | 924 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
925 | |
926 | if (cfq_cfqq_sync(cfqq)) | |
927 | cfqd->sync_flight++; | |
1da177e4 LT |
928 | } |
929 | ||
930 | /* | |
931 | * return expired entry, or NULL to just start from scratch in rbtree | |
932 | */ | |
5e705374 | 933 | static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 LT |
934 | { |
935 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 936 | struct request *rq; |
89850f7e | 937 | int fifo; |
1da177e4 | 938 | |
3b18152c | 939 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 940 | return NULL; |
cb887411 JA |
941 | |
942 | cfq_mark_cfqq_fifo_expire(cfqq); | |
943 | ||
89850f7e JA |
944 | if (list_empty(&cfqq->fifo)) |
945 | return NULL; | |
1da177e4 | 946 | |
6d048f53 | 947 | fifo = cfq_cfqq_sync(cfqq); |
89850f7e | 948 | rq = rq_entry_fifo(cfqq->fifo.next); |
1da177e4 | 949 | |
6d048f53 JA |
950 | if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) |
951 | return NULL; | |
1da177e4 | 952 | |
6d048f53 | 953 | return rq; |
1da177e4 LT |
954 | } |
955 | ||
22e2c507 JA |
956 | static inline int |
957 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
958 | { | |
959 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 960 | |
22e2c507 | 961 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 962 | |
22e2c507 | 963 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
964 | } |
965 | ||
22e2c507 | 966 | /* |
498d3aa2 JA |
967 | * Select a queue for service. If we have a current active queue, |
968 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 969 | */ |
1b5ed5e1 | 970 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 971 | { |
1da177e4 | 972 | struct cfq_queue *cfqq; |
1da177e4 | 973 | |
22e2c507 JA |
974 | cfqq = cfqd->active_queue; |
975 | if (!cfqq) | |
976 | goto new_queue; | |
1da177e4 | 977 | |
22e2c507 | 978 | /* |
6d048f53 | 979 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 980 | */ |
6d048f53 | 981 | if (cfq_slice_used(cfqq)) |
3b18152c | 982 | goto expire; |
1da177e4 | 983 | |
22e2c507 | 984 | /* |
6d048f53 JA |
985 | * The active queue has requests and isn't expired, allow it to |
986 | * dispatch. | |
22e2c507 | 987 | */ |
dd67d051 | 988 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 989 | goto keep_queue; |
6d048f53 JA |
990 | |
991 | /* | |
992 | * No requests pending. If the active queue still has requests in | |
993 | * flight or is idling for a new request, allow either of these | |
994 | * conditions to happen (or time out) before selecting a new queue. | |
995 | */ | |
cc197479 JA |
996 | if (timer_pending(&cfqd->idle_slice_timer) || |
997 | (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { | |
caaa5f9f JA |
998 | cfqq = NULL; |
999 | goto keep_queue; | |
22e2c507 JA |
1000 | } |
1001 | ||
3b18152c | 1002 | expire: |
6084cdda | 1003 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
1004 | new_queue: |
1005 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 1006 | keep_queue: |
3b18152c | 1007 | return cfqq; |
22e2c507 JA |
1008 | } |
1009 | ||
498d3aa2 JA |
1010 | /* |
1011 | * Dispatch some requests from cfqq, moving them to the request queue | |
1012 | * dispatch list. | |
1013 | */ | |
22e2c507 JA |
1014 | static int |
1015 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1016 | int max_dispatch) | |
1017 | { | |
1018 | int dispatched = 0; | |
1019 | ||
dd67d051 | 1020 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
22e2c507 JA |
1021 | |
1022 | do { | |
5e705374 | 1023 | struct request *rq; |
1da177e4 LT |
1024 | |
1025 | /* | |
22e2c507 | 1026 | * follow expired path, else get first next available |
1da177e4 | 1027 | */ |
5e705374 JA |
1028 | if ((rq = cfq_check_fifo(cfqq)) == NULL) |
1029 | rq = cfqq->next_rq; | |
22e2c507 JA |
1030 | |
1031 | /* | |
1032 | * finally, insert request into driver dispatch list | |
1033 | */ | |
5e705374 | 1034 | cfq_dispatch_insert(cfqd->queue, rq); |
1da177e4 | 1035 | |
22e2c507 | 1036 | dispatched++; |
1da177e4 | 1037 | |
22e2c507 | 1038 | if (!cfqd->active_cic) { |
5e705374 JA |
1039 | atomic_inc(&RQ_CIC(rq)->ioc->refcount); |
1040 | cfqd->active_cic = RQ_CIC(rq); | |
22e2c507 | 1041 | } |
1da177e4 | 1042 | |
dd67d051 | 1043 | if (RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 JA |
1044 | break; |
1045 | ||
1046 | } while (dispatched < max_dispatch); | |
1047 | ||
22e2c507 JA |
1048 | /* |
1049 | * expire an async queue immediately if it has used up its slice. idle | |
1050 | * queue always expire after 1 dispatch round. | |
1051 | */ | |
a9938006 | 1052 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
20e493a8 | 1053 | dispatched >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
a9938006 | 1054 | cfq_class_idle(cfqq))) { |
44f7c160 | 1055 | cfqq->slice_end = jiffies + 1; |
6084cdda | 1056 | cfq_slice_expired(cfqd, 0); |
44f7c160 | 1057 | } |
22e2c507 JA |
1058 | |
1059 | return dispatched; | |
1060 | } | |
1061 | ||
d9e7620e JA |
1062 | static inline int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
1063 | { | |
1064 | int dispatched = 0; | |
1065 | ||
1066 | while (cfqq->next_rq) { | |
1067 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1068 | dispatched++; | |
1069 | } | |
1070 | ||
1071 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1072 | return dispatched; | |
1073 | } | |
1074 | ||
498d3aa2 JA |
1075 | /* |
1076 | * Drain our current requests. Used for barriers and when switching | |
1077 | * io schedulers on-the-fly. | |
1078 | */ | |
d9e7620e | 1079 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1080 | { |
d9e7620e JA |
1081 | int dispatched = 0; |
1082 | struct rb_node *n; | |
1083 | ||
cc09e299 | 1084 | while ((n = cfq_rb_first(&cfqd->service_tree)) != NULL) { |
d9e7620e | 1085 | struct cfq_queue *cfqq = rb_entry(n, struct cfq_queue, rb_node); |
1b5ed5e1 | 1086 | |
d9e7620e JA |
1087 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1088 | } | |
1b5ed5e1 | 1089 | |
6084cdda | 1090 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1091 | |
1092 | BUG_ON(cfqd->busy_queues); | |
1093 | ||
1094 | return dispatched; | |
1095 | } | |
1096 | ||
165125e1 | 1097 | static int cfq_dispatch_requests(struct request_queue *q, int force) |
22e2c507 JA |
1098 | { |
1099 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
6d048f53 | 1100 | struct cfq_queue *cfqq; |
caaa5f9f | 1101 | int dispatched; |
22e2c507 JA |
1102 | |
1103 | if (!cfqd->busy_queues) | |
1104 | return 0; | |
1105 | ||
1b5ed5e1 TH |
1106 | if (unlikely(force)) |
1107 | return cfq_forced_dispatch(cfqd); | |
1108 | ||
caaa5f9f | 1109 | dispatched = 0; |
caaa5f9f | 1110 | while ((cfqq = cfq_select_queue(cfqd)) != NULL) { |
b4878f24 JA |
1111 | int max_dispatch; |
1112 | ||
3ed9a296 JA |
1113 | max_dispatch = cfqd->cfq_quantum; |
1114 | if (cfq_class_idle(cfqq)) | |
1115 | max_dispatch = 1; | |
1116 | ||
1117 | if (cfqq->dispatched >= max_dispatch) { | |
1118 | if (cfqd->busy_queues > 1) | |
6d048f53 | 1119 | break; |
3ed9a296 | 1120 | if (cfqq->dispatched >= 4 * max_dispatch) |
a9938006 JA |
1121 | break; |
1122 | } | |
9ede209e | 1123 | |
3ed9a296 JA |
1124 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) |
1125 | break; | |
1126 | ||
3b18152c JA |
1127 | cfq_clear_cfqq_must_dispatch(cfqq); |
1128 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1129 | del_timer(&cfqd->idle_slice_timer); |
1130 | ||
caaa5f9f | 1131 | dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1132 | } |
1133 | ||
caaa5f9f | 1134 | return dispatched; |
1da177e4 LT |
1135 | } |
1136 | ||
1da177e4 | 1137 | /* |
5e705374 JA |
1138 | * task holds one reference to the queue, dropped when task exits. each rq |
1139 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1140 | * |
1141 | * queue lock must be held here. | |
1142 | */ | |
1143 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1144 | { | |
22e2c507 JA |
1145 | struct cfq_data *cfqd = cfqq->cfqd; |
1146 | ||
1147 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1148 | |
1149 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1150 | return; | |
1151 | ||
1152 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1153 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1154 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1155 | |
28f95cbc | 1156 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1157 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1158 | cfq_schedule_dispatch(cfqd); |
1159 | } | |
22e2c507 | 1160 | |
1da177e4 LT |
1161 | kmem_cache_free(cfq_pool, cfqq); |
1162 | } | |
1163 | ||
e2d74ac0 | 1164 | static void cfq_free_io_context(struct io_context *ioc) |
1da177e4 | 1165 | { |
22e2c507 | 1166 | struct cfq_io_context *__cic; |
e2d74ac0 JA |
1167 | struct rb_node *n; |
1168 | int freed = 0; | |
1da177e4 | 1169 | |
597bc485 JA |
1170 | ioc->ioc_data = NULL; |
1171 | ||
e2d74ac0 JA |
1172 | while ((n = rb_first(&ioc->cic_root)) != NULL) { |
1173 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1174 | rb_erase(&__cic->rb_node, &ioc->cic_root); | |
22e2c507 | 1175 | kmem_cache_free(cfq_ioc_pool, __cic); |
334e94de | 1176 | freed++; |
1da177e4 LT |
1177 | } |
1178 | ||
4050cf16 JA |
1179 | elv_ioc_count_mod(ioc_count, -freed); |
1180 | ||
1181 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) | |
334e94de | 1182 | complete(ioc_gone); |
1da177e4 LT |
1183 | } |
1184 | ||
89850f7e | 1185 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1186 | { |
28f95cbc | 1187 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1188 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1189 | cfq_schedule_dispatch(cfqd); |
1190 | } | |
22e2c507 | 1191 | |
89850f7e JA |
1192 | cfq_put_queue(cfqq); |
1193 | } | |
22e2c507 | 1194 | |
89850f7e JA |
1195 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1196 | struct cfq_io_context *cic) | |
1197 | { | |
fc46379d JA |
1198 | list_del_init(&cic->queue_list); |
1199 | smp_wmb(); | |
1200 | cic->key = NULL; | |
1201 | ||
12a05732 | 1202 | if (cic->cfqq[ASYNC]) { |
89850f7e | 1203 | cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]); |
12a05732 AV |
1204 | cic->cfqq[ASYNC] = NULL; |
1205 | } | |
1206 | ||
1207 | if (cic->cfqq[SYNC]) { | |
89850f7e | 1208 | cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]); |
12a05732 AV |
1209 | cic->cfqq[SYNC] = NULL; |
1210 | } | |
89850f7e JA |
1211 | } |
1212 | ||
89850f7e JA |
1213 | static void cfq_exit_single_io_context(struct cfq_io_context *cic) |
1214 | { | |
1215 | struct cfq_data *cfqd = cic->key; | |
1216 | ||
89850f7e | 1217 | if (cfqd) { |
165125e1 | 1218 | struct request_queue *q = cfqd->queue; |
89850f7e | 1219 | |
fc46379d | 1220 | spin_lock_irq(q->queue_lock); |
89850f7e | 1221 | __cfq_exit_single_io_context(cfqd, cic); |
fc46379d | 1222 | spin_unlock_irq(q->queue_lock); |
89850f7e | 1223 | } |
1da177e4 LT |
1224 | } |
1225 | ||
498d3aa2 JA |
1226 | /* |
1227 | * The process that ioc belongs to has exited, we need to clean up | |
1228 | * and put the internal structures we have that belongs to that process. | |
1229 | */ | |
e2d74ac0 | 1230 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1231 | { |
22e2c507 | 1232 | struct cfq_io_context *__cic; |
e2d74ac0 | 1233 | struct rb_node *n; |
22e2c507 | 1234 | |
597bc485 JA |
1235 | ioc->ioc_data = NULL; |
1236 | ||
1da177e4 LT |
1237 | /* |
1238 | * put the reference this task is holding to the various queues | |
1239 | */ | |
e2d74ac0 JA |
1240 | n = rb_first(&ioc->cic_root); |
1241 | while (n != NULL) { | |
1242 | __cic = rb_entry(n, struct cfq_io_context, rb_node); | |
1243 | ||
22e2c507 | 1244 | cfq_exit_single_io_context(__cic); |
e2d74ac0 | 1245 | n = rb_next(n); |
1da177e4 | 1246 | } |
1da177e4 LT |
1247 | } |
1248 | ||
22e2c507 | 1249 | static struct cfq_io_context * |
8267e268 | 1250 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1251 | { |
b5deef90 | 1252 | struct cfq_io_context *cic; |
1da177e4 | 1253 | |
94f6030c CL |
1254 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1255 | cfqd->queue->node); | |
1da177e4 | 1256 | if (cic) { |
22e2c507 | 1257 | cic->last_end_request = jiffies; |
553698f9 | 1258 | INIT_LIST_HEAD(&cic->queue_list); |
22e2c507 JA |
1259 | cic->dtor = cfq_free_io_context; |
1260 | cic->exit = cfq_exit_io_context; | |
4050cf16 | 1261 | elv_ioc_count_inc(ioc_count); |
1da177e4 LT |
1262 | } |
1263 | ||
1264 | return cic; | |
1265 | } | |
1266 | ||
22e2c507 JA |
1267 | static void cfq_init_prio_data(struct cfq_queue *cfqq) |
1268 | { | |
1269 | struct task_struct *tsk = current; | |
1270 | int ioprio_class; | |
1271 | ||
3b18152c | 1272 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1273 | return; |
1274 | ||
1275 | ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); | |
1276 | switch (ioprio_class) { | |
1277 | default: | |
1278 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1279 | case IOPRIO_CLASS_NONE: | |
1280 | /* | |
1281 | * no prio set, place us in the middle of the BE classes | |
1282 | */ | |
1283 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1284 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1285 | break; | |
1286 | case IOPRIO_CLASS_RT: | |
1287 | cfqq->ioprio = task_ioprio(tsk); | |
1288 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1289 | break; | |
1290 | case IOPRIO_CLASS_BE: | |
1291 | cfqq->ioprio = task_ioprio(tsk); | |
1292 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1293 | break; | |
1294 | case IOPRIO_CLASS_IDLE: | |
1295 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1296 | cfqq->ioprio = 7; | |
3b18152c | 1297 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1298 | break; |
1299 | } | |
1300 | ||
1301 | /* | |
1302 | * keep track of original prio settings in case we have to temporarily | |
1303 | * elevate the priority of this queue | |
1304 | */ | |
1305 | cfqq->org_ioprio = cfqq->ioprio; | |
1306 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1307 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1308 | } |
1309 | ||
478a82b0 | 1310 | static inline void changed_ioprio(struct cfq_io_context *cic) |
22e2c507 | 1311 | { |
478a82b0 AV |
1312 | struct cfq_data *cfqd = cic->key; |
1313 | struct cfq_queue *cfqq; | |
c1b707d2 | 1314 | unsigned long flags; |
35e6077c | 1315 | |
caaa5f9f JA |
1316 | if (unlikely(!cfqd)) |
1317 | return; | |
1318 | ||
c1b707d2 | 1319 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f JA |
1320 | |
1321 | cfqq = cic->cfqq[ASYNC]; | |
1322 | if (cfqq) { | |
1323 | struct cfq_queue *new_cfqq; | |
91fac317 | 1324 | new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc->task, |
caaa5f9f JA |
1325 | GFP_ATOMIC); |
1326 | if (new_cfqq) { | |
1327 | cic->cfqq[ASYNC] = new_cfqq; | |
1328 | cfq_put_queue(cfqq); | |
1329 | } | |
22e2c507 | 1330 | } |
caaa5f9f JA |
1331 | |
1332 | cfqq = cic->cfqq[SYNC]; | |
1333 | if (cfqq) | |
1334 | cfq_mark_cfqq_prio_changed(cfqq); | |
1335 | ||
c1b707d2 | 1336 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
1337 | } |
1338 | ||
fc46379d | 1339 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 1340 | { |
a6a0763a | 1341 | struct cfq_io_context *cic; |
e2d74ac0 | 1342 | struct rb_node *n; |
a6a0763a | 1343 | |
fc46379d | 1344 | ioc->ioprio_changed = 0; |
a6a0763a | 1345 | |
e2d74ac0 JA |
1346 | n = rb_first(&ioc->cic_root); |
1347 | while (n != NULL) { | |
1348 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
3793c65c | 1349 | |
478a82b0 | 1350 | changed_ioprio(cic); |
e2d74ac0 JA |
1351 | n = rb_next(n); |
1352 | } | |
22e2c507 JA |
1353 | } |
1354 | ||
1355 | static struct cfq_queue * | |
15c31be4 JA |
1356 | cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync, |
1357 | struct task_struct *tsk, gfp_t gfp_mask) | |
22e2c507 | 1358 | { |
22e2c507 | 1359 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 1360 | struct cfq_io_context *cic; |
22e2c507 JA |
1361 | |
1362 | retry: | |
91fac317 VT |
1363 | cic = cfq_cic_rb_lookup(cfqd, tsk->io_context); |
1364 | /* cic always exists here */ | |
1365 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 JA |
1366 | |
1367 | if (!cfqq) { | |
1368 | if (new_cfqq) { | |
1369 | cfqq = new_cfqq; | |
1370 | new_cfqq = NULL; | |
1371 | } else if (gfp_mask & __GFP_WAIT) { | |
89850f7e JA |
1372 | /* |
1373 | * Inform the allocator of the fact that we will | |
1374 | * just repeat this allocation if it fails, to allow | |
1375 | * the allocator to do whatever it needs to attempt to | |
1376 | * free memory. | |
1377 | */ | |
22e2c507 | 1378 | spin_unlock_irq(cfqd->queue->queue_lock); |
94f6030c CL |
1379 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
1380 | gfp_mask | __GFP_NOFAIL | __GFP_ZERO, | |
1381 | cfqd->queue->node); | |
22e2c507 JA |
1382 | spin_lock_irq(cfqd->queue->queue_lock); |
1383 | goto retry; | |
1384 | } else { | |
94f6030c CL |
1385 | cfqq = kmem_cache_alloc_node(cfq_pool, |
1386 | gfp_mask | __GFP_ZERO, | |
1387 | cfqd->queue->node); | |
22e2c507 JA |
1388 | if (!cfqq) |
1389 | goto out; | |
1390 | } | |
1391 | ||
d9e7620e | 1392 | RB_CLEAR_NODE(&cfqq->rb_node); |
22e2c507 JA |
1393 | INIT_LIST_HEAD(&cfqq->fifo); |
1394 | ||
22e2c507 JA |
1395 | atomic_set(&cfqq->ref, 0); |
1396 | cfqq->cfqd = cfqd; | |
c5b680f3 | 1397 | |
91fac317 | 1398 | if (is_sync) { |
a9938006 | 1399 | cfq_mark_cfqq_idle_window(cfqq); |
91fac317 VT |
1400 | cfq_mark_cfqq_sync(cfqq); |
1401 | } | |
a9938006 | 1402 | |
3b18152c | 1403 | cfq_mark_cfqq_prio_changed(cfqq); |
53b03744 | 1404 | cfq_mark_cfqq_queue_new(cfqq); |
91fac317 | 1405 | |
3b18152c | 1406 | cfq_init_prio_data(cfqq); |
22e2c507 JA |
1407 | } |
1408 | ||
1409 | if (new_cfqq) | |
1410 | kmem_cache_free(cfq_pool, new_cfqq); | |
1411 | ||
22e2c507 JA |
1412 | out: |
1413 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1414 | return cfqq; | |
1415 | } | |
1416 | ||
c2dea2d1 VT |
1417 | static struct cfq_queue ** |
1418 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
1419 | { | |
1420 | switch(ioprio_class) { | |
1421 | case IOPRIO_CLASS_RT: | |
1422 | return &cfqd->async_cfqq[0][ioprio]; | |
1423 | case IOPRIO_CLASS_BE: | |
1424 | return &cfqd->async_cfqq[1][ioprio]; | |
1425 | case IOPRIO_CLASS_IDLE: | |
1426 | return &cfqd->async_idle_cfqq; | |
1427 | default: | |
1428 | BUG(); | |
1429 | } | |
1430 | } | |
1431 | ||
15c31be4 JA |
1432 | static struct cfq_queue * |
1433 | cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk, | |
1434 | gfp_t gfp_mask) | |
1435 | { | |
1436 | const int ioprio = task_ioprio(tsk); | |
c2dea2d1 VT |
1437 | const int ioprio_class = task_ioprio_class(tsk); |
1438 | struct cfq_queue **async_cfqq = NULL; | |
15c31be4 JA |
1439 | struct cfq_queue *cfqq = NULL; |
1440 | ||
c2dea2d1 VT |
1441 | if (!is_sync) { |
1442 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
1443 | cfqq = *async_cfqq; | |
1444 | } | |
1445 | ||
15c31be4 JA |
1446 | if (!cfqq) |
1447 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, tsk, gfp_mask); | |
1448 | ||
1449 | /* | |
1450 | * pin the queue now that it's allocated, scheduler exit will prune it | |
1451 | */ | |
c2dea2d1 | 1452 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 1453 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 1454 | *async_cfqq = cfqq; |
15c31be4 JA |
1455 | } |
1456 | ||
1457 | atomic_inc(&cfqq->ref); | |
1458 | return cfqq; | |
1459 | } | |
1460 | ||
498d3aa2 JA |
1461 | /* |
1462 | * We drop cfq io contexts lazily, so we may find a dead one. | |
1463 | */ | |
dbecf3ab OH |
1464 | static void |
1465 | cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) | |
1466 | { | |
fc46379d | 1467 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 JA |
1468 | |
1469 | if (ioc->ioc_data == cic) | |
1470 | ioc->ioc_data = NULL; | |
1471 | ||
dbecf3ab | 1472 | rb_erase(&cic->rb_node, &ioc->cic_root); |
dbecf3ab | 1473 | kmem_cache_free(cfq_ioc_pool, cic); |
4050cf16 | 1474 | elv_ioc_count_dec(ioc_count); |
dbecf3ab OH |
1475 | } |
1476 | ||
e2d74ac0 JA |
1477 | static struct cfq_io_context * |
1478 | cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
1479 | { | |
dbecf3ab | 1480 | struct rb_node *n; |
e2d74ac0 | 1481 | struct cfq_io_context *cic; |
be3b0753 | 1482 | void *k, *key = cfqd; |
e2d74ac0 | 1483 | |
91fac317 VT |
1484 | if (unlikely(!ioc)) |
1485 | return NULL; | |
1486 | ||
597bc485 JA |
1487 | /* |
1488 | * we maintain a last-hit cache, to avoid browsing over the tree | |
1489 | */ | |
1490 | cic = ioc->ioc_data; | |
1491 | if (cic && cic->key == cfqd) | |
1492 | return cic; | |
1493 | ||
dbecf3ab OH |
1494 | restart: |
1495 | n = ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1496 | while (n) { |
1497 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1498 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1499 | k = cic->key; | |
1500 | if (unlikely(!k)) { | |
dbecf3ab OH |
1501 | cfq_drop_dead_cic(ioc, cic); |
1502 | goto restart; | |
1503 | } | |
e2d74ac0 | 1504 | |
be3b0753 | 1505 | if (key < k) |
e2d74ac0 | 1506 | n = n->rb_left; |
be3b0753 | 1507 | else if (key > k) |
e2d74ac0 | 1508 | n = n->rb_right; |
597bc485 JA |
1509 | else { |
1510 | ioc->ioc_data = cic; | |
e2d74ac0 | 1511 | return cic; |
597bc485 | 1512 | } |
e2d74ac0 JA |
1513 | } |
1514 | ||
1515 | return NULL; | |
1516 | } | |
1517 | ||
1518 | static inline void | |
1519 | cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
1520 | struct cfq_io_context *cic) | |
1521 | { | |
dbecf3ab OH |
1522 | struct rb_node **p; |
1523 | struct rb_node *parent; | |
e2d74ac0 | 1524 | struct cfq_io_context *__cic; |
0261d688 | 1525 | unsigned long flags; |
be3b0753 | 1526 | void *k; |
e2d74ac0 | 1527 | |
e2d74ac0 JA |
1528 | cic->ioc = ioc; |
1529 | cic->key = cfqd; | |
1530 | ||
dbecf3ab OH |
1531 | restart: |
1532 | parent = NULL; | |
1533 | p = &ioc->cic_root.rb_node; | |
e2d74ac0 JA |
1534 | while (*p) { |
1535 | parent = *p; | |
1536 | __cic = rb_entry(parent, struct cfq_io_context, rb_node); | |
be3b0753 OH |
1537 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1538 | k = __cic->key; | |
1539 | if (unlikely(!k)) { | |
be33c3a6 | 1540 | cfq_drop_dead_cic(ioc, __cic); |
dbecf3ab OH |
1541 | goto restart; |
1542 | } | |
e2d74ac0 | 1543 | |
be3b0753 | 1544 | if (cic->key < k) |
e2d74ac0 | 1545 | p = &(*p)->rb_left; |
be3b0753 | 1546 | else if (cic->key > k) |
e2d74ac0 JA |
1547 | p = &(*p)->rb_right; |
1548 | else | |
1549 | BUG(); | |
1550 | } | |
1551 | ||
1552 | rb_link_node(&cic->rb_node, parent, p); | |
1553 | rb_insert_color(&cic->rb_node, &ioc->cic_root); | |
fc46379d | 1554 | |
0261d688 | 1555 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
e2d74ac0 | 1556 | list_add(&cic->queue_list, &cfqd->cic_list); |
0261d688 | 1557 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
e2d74ac0 JA |
1558 | } |
1559 | ||
1da177e4 LT |
1560 | /* |
1561 | * Setup general io context and cfq io context. There can be several cfq | |
1562 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1563 | * than one device managed by cfq. |
1da177e4 LT |
1564 | */ |
1565 | static struct cfq_io_context * | |
e2d74ac0 | 1566 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1567 | { |
22e2c507 | 1568 | struct io_context *ioc = NULL; |
1da177e4 | 1569 | struct cfq_io_context *cic; |
1da177e4 | 1570 | |
22e2c507 | 1571 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1572 | |
b5deef90 | 1573 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
1574 | if (!ioc) |
1575 | return NULL; | |
1576 | ||
e2d74ac0 JA |
1577 | cic = cfq_cic_rb_lookup(cfqd, ioc); |
1578 | if (cic) | |
1579 | goto out; | |
1da177e4 | 1580 | |
e2d74ac0 JA |
1581 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1582 | if (cic == NULL) | |
1583 | goto err; | |
1da177e4 | 1584 | |
e2d74ac0 | 1585 | cfq_cic_link(cfqd, ioc, cic); |
1da177e4 | 1586 | out: |
fc46379d JA |
1587 | smp_read_barrier_depends(); |
1588 | if (unlikely(ioc->ioprio_changed)) | |
1589 | cfq_ioc_set_ioprio(ioc); | |
1590 | ||
1da177e4 LT |
1591 | return cic; |
1592 | err: | |
1593 | put_io_context(ioc); | |
1594 | return NULL; | |
1595 | } | |
1596 | ||
22e2c507 JA |
1597 | static void |
1598 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1599 | { |
aaf1228d JA |
1600 | unsigned long elapsed = jiffies - cic->last_end_request; |
1601 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 1602 | |
22e2c507 JA |
1603 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1604 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1605 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1606 | } | |
1da177e4 | 1607 | |
206dc69b | 1608 | static void |
6d048f53 JA |
1609 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, |
1610 | struct request *rq) | |
206dc69b JA |
1611 | { |
1612 | sector_t sdist; | |
1613 | u64 total; | |
1614 | ||
5e705374 JA |
1615 | if (cic->last_request_pos < rq->sector) |
1616 | sdist = rq->sector - cic->last_request_pos; | |
206dc69b | 1617 | else |
5e705374 | 1618 | sdist = cic->last_request_pos - rq->sector; |
206dc69b JA |
1619 | |
1620 | /* | |
1621 | * Don't allow the seek distance to get too large from the | |
1622 | * odd fragment, pagein, etc | |
1623 | */ | |
1624 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1625 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1626 | else | |
1627 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1628 | ||
1629 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1630 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1631 | total = cic->seek_total + (cic->seek_samples/2); | |
1632 | do_div(total, cic->seek_samples); | |
1633 | cic->seek_mean = (sector_t)total; | |
1634 | } | |
1da177e4 | 1635 | |
22e2c507 JA |
1636 | /* |
1637 | * Disable idle window if the process thinks too long or seeks so much that | |
1638 | * it doesn't matter | |
1639 | */ | |
1640 | static void | |
1641 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1642 | struct cfq_io_context *cic) | |
1643 | { | |
1be92f2f JA |
1644 | int enable_idle; |
1645 | ||
1646 | if (!cfq_cfqq_sync(cfqq)) | |
1647 | return; | |
1648 | ||
1649 | enable_idle = cfq_cfqq_idle_window(cfqq); | |
1da177e4 | 1650 | |
caaa5f9f JA |
1651 | if (!cic->ioc->task || !cfqd->cfq_slice_idle || |
1652 | (cfqd->hw_tag && CIC_SEEKY(cic))) | |
22e2c507 JA |
1653 | enable_idle = 0; |
1654 | else if (sample_valid(cic->ttime_samples)) { | |
1655 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1656 | enable_idle = 0; | |
1657 | else | |
1658 | enable_idle = 1; | |
1da177e4 LT |
1659 | } |
1660 | ||
3b18152c JA |
1661 | if (enable_idle) |
1662 | cfq_mark_cfqq_idle_window(cfqq); | |
1663 | else | |
1664 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1665 | } |
1da177e4 | 1666 | |
22e2c507 JA |
1667 | /* |
1668 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1669 | * no or if we aren't sure, a 1 will cause a preempt. | |
1670 | */ | |
1671 | static int | |
1672 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
5e705374 | 1673 | struct request *rq) |
22e2c507 | 1674 | { |
6d048f53 | 1675 | struct cfq_queue *cfqq; |
22e2c507 | 1676 | |
6d048f53 JA |
1677 | cfqq = cfqd->active_queue; |
1678 | if (!cfqq) | |
22e2c507 JA |
1679 | return 0; |
1680 | ||
6d048f53 JA |
1681 | if (cfq_slice_used(cfqq)) |
1682 | return 1; | |
1683 | ||
1684 | if (cfq_class_idle(new_cfqq)) | |
caaa5f9f | 1685 | return 0; |
22e2c507 JA |
1686 | |
1687 | if (cfq_class_idle(cfqq)) | |
1688 | return 1; | |
1e3335de | 1689 | |
374f84ac JA |
1690 | /* |
1691 | * if the new request is sync, but the currently running queue is | |
1692 | * not, let the sync request have priority. | |
1693 | */ | |
5e705374 | 1694 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 | 1695 | return 1; |
1e3335de | 1696 | |
374f84ac JA |
1697 | /* |
1698 | * So both queues are sync. Let the new request get disk time if | |
1699 | * it's a metadata request and the current queue is doing regular IO. | |
1700 | */ | |
1701 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
1702 | return 1; | |
22e2c507 | 1703 | |
1e3335de JA |
1704 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
1705 | return 0; | |
1706 | ||
1707 | /* | |
1708 | * if this request is as-good as one we would expect from the | |
1709 | * current cfqq, let it preempt | |
1710 | */ | |
6d048f53 | 1711 | if (cfq_rq_close(cfqd, rq)) |
1e3335de JA |
1712 | return 1; |
1713 | ||
22e2c507 JA |
1714 | return 0; |
1715 | } | |
1716 | ||
1717 | /* | |
1718 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1719 | * let it have half of its nominal slice. | |
1720 | */ | |
1721 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1722 | { | |
6084cdda | 1723 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 1724 | |
bf572256 JA |
1725 | /* |
1726 | * Put the new queue at the front of the of the current list, | |
1727 | * so we know that it will be selected next. | |
1728 | */ | |
1729 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
1730 | |
1731 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 1732 | |
44f7c160 JA |
1733 | cfqq->slice_end = 0; |
1734 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
1735 | } |
1736 | ||
22e2c507 | 1737 | /* |
5e705374 | 1738 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
1739 | * something we should do about it |
1740 | */ | |
1741 | static void | |
5e705374 JA |
1742 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1743 | struct request *rq) | |
22e2c507 | 1744 | { |
5e705374 | 1745 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 1746 | |
374f84ac JA |
1747 | if (rq_is_meta(rq)) |
1748 | cfqq->meta_pending++; | |
1749 | ||
9c2c38a1 | 1750 | cfq_update_io_thinktime(cfqd, cic); |
6d048f53 | 1751 | cfq_update_io_seektime(cfqd, cic, rq); |
9c2c38a1 JA |
1752 | cfq_update_idle_window(cfqd, cfqq, cic); |
1753 | ||
5e705374 | 1754 | cic->last_request_pos = rq->sector + rq->nr_sectors; |
22e2c507 JA |
1755 | |
1756 | if (cfqq == cfqd->active_queue) { | |
1757 | /* | |
1758 | * if we are waiting for a request for this queue, let it rip | |
1759 | * immediately and flag that we must not expire this queue | |
1760 | * just now | |
1761 | */ | |
3b18152c JA |
1762 | if (cfq_cfqq_wait_request(cfqq)) { |
1763 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 | 1764 | del_timer(&cfqd->idle_slice_timer); |
dc72ef4a | 1765 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1766 | } |
5e705374 | 1767 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
1768 | /* |
1769 | * not the active queue - expire current slice if it is | |
1770 | * idle and has expired it's mean thinktime or this new queue | |
1771 | * has some old slice time left and is of higher priority | |
1772 | */ | |
1773 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1774 | cfq_mark_cfqq_must_dispatch(cfqq); |
dc72ef4a | 1775 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1776 | } |
1da177e4 LT |
1777 | } |
1778 | ||
165125e1 | 1779 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 1780 | { |
b4878f24 | 1781 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1782 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 JA |
1783 | |
1784 | cfq_init_prio_data(cfqq); | |
1da177e4 | 1785 | |
5e705374 | 1786 | cfq_add_rq_rb(rq); |
1da177e4 | 1787 | |
22e2c507 JA |
1788 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1789 | ||
5e705374 | 1790 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
1791 | } |
1792 | ||
165125e1 | 1793 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 1794 | { |
5e705374 | 1795 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 1796 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 1797 | const int sync = rq_is_sync(rq); |
b4878f24 | 1798 | unsigned long now; |
1da177e4 | 1799 | |
b4878f24 | 1800 | now = jiffies; |
1da177e4 | 1801 | |
b4878f24 | 1802 | WARN_ON(!cfqd->rq_in_driver); |
6d048f53 | 1803 | WARN_ON(!cfqq->dispatched); |
b4878f24 | 1804 | cfqd->rq_in_driver--; |
6d048f53 | 1805 | cfqq->dispatched--; |
1da177e4 | 1806 | |
3ed9a296 JA |
1807 | if (cfq_cfqq_sync(cfqq)) |
1808 | cfqd->sync_flight--; | |
1809 | ||
b4878f24 JA |
1810 | if (!cfq_class_idle(cfqq)) |
1811 | cfqd->last_end_request = now; | |
3b18152c | 1812 | |
caaa5f9f | 1813 | if (sync) |
5e705374 | 1814 | RQ_CIC(rq)->last_end_request = now; |
caaa5f9f JA |
1815 | |
1816 | /* | |
1817 | * If this is the active queue, check if it needs to be expired, | |
1818 | * or if we want to idle in case it has no pending requests. | |
1819 | */ | |
1820 | if (cfqd->active_queue == cfqq) { | |
44f7c160 JA |
1821 | if (cfq_cfqq_slice_new(cfqq)) { |
1822 | cfq_set_prio_slice(cfqd, cfqq); | |
1823 | cfq_clear_cfqq_slice_new(cfqq); | |
1824 | } | |
1825 | if (cfq_slice_used(cfqq)) | |
6084cdda | 1826 | cfq_slice_expired(cfqd, 1); |
6d048f53 JA |
1827 | else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) |
1828 | cfq_arm_slice_timer(cfqd); | |
caaa5f9f | 1829 | } |
6d048f53 JA |
1830 | |
1831 | if (!cfqd->rq_in_driver) | |
1832 | cfq_schedule_dispatch(cfqd); | |
1da177e4 LT |
1833 | } |
1834 | ||
22e2c507 JA |
1835 | /* |
1836 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1837 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1838 | */ | |
1839 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1840 | { |
22e2c507 JA |
1841 | if (has_fs_excl()) { |
1842 | /* | |
1843 | * boost idle prio on transactions that would lock out other | |
1844 | * users of the filesystem | |
1845 | */ | |
1846 | if (cfq_class_idle(cfqq)) | |
1847 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1848 | if (cfqq->ioprio > IOPRIO_NORM) | |
1849 | cfqq->ioprio = IOPRIO_NORM; | |
1850 | } else { | |
1851 | /* | |
1852 | * check if we need to unboost the queue | |
1853 | */ | |
1854 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1855 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1856 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1857 | cfqq->ioprio = cfqq->org_ioprio; | |
1858 | } | |
22e2c507 | 1859 | } |
1da177e4 | 1860 | |
89850f7e | 1861 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 1862 | { |
3b18152c | 1863 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && |
99f95e52 | 1864 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1865 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1866 | return ELV_MQUEUE_MUST; |
3b18152c | 1867 | } |
1da177e4 | 1868 | |
22e2c507 | 1869 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
1870 | } |
1871 | ||
165125e1 | 1872 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
1873 | { |
1874 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1875 | struct task_struct *tsk = current; | |
91fac317 | 1876 | struct cfq_io_context *cic; |
22e2c507 JA |
1877 | struct cfq_queue *cfqq; |
1878 | ||
1879 | /* | |
1880 | * don't force setup of a queue from here, as a call to may_queue | |
1881 | * does not necessarily imply that a request actually will be queued. | |
1882 | * so just lookup a possibly existing queue, or return 'may queue' | |
1883 | * if that fails | |
1884 | */ | |
91fac317 VT |
1885 | cic = cfq_cic_rb_lookup(cfqd, tsk->io_context); |
1886 | if (!cic) | |
1887 | return ELV_MQUEUE_MAY; | |
1888 | ||
1889 | cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC); | |
22e2c507 JA |
1890 | if (cfqq) { |
1891 | cfq_init_prio_data(cfqq); | |
1892 | cfq_prio_boost(cfqq); | |
1893 | ||
89850f7e | 1894 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
1895 | } |
1896 | ||
1897 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1898 | } |
1899 | ||
1da177e4 LT |
1900 | /* |
1901 | * queue lock held here | |
1902 | */ | |
bb37b94c | 1903 | static void cfq_put_request(struct request *rq) |
1da177e4 | 1904 | { |
5e705374 | 1905 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 1906 | |
5e705374 | 1907 | if (cfqq) { |
22e2c507 | 1908 | const int rw = rq_data_dir(rq); |
1da177e4 | 1909 | |
22e2c507 JA |
1910 | BUG_ON(!cfqq->allocated[rw]); |
1911 | cfqq->allocated[rw]--; | |
1da177e4 | 1912 | |
5e705374 | 1913 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 1914 | |
1da177e4 | 1915 | rq->elevator_private = NULL; |
5e705374 | 1916 | rq->elevator_private2 = NULL; |
1da177e4 | 1917 | |
1da177e4 LT |
1918 | cfq_put_queue(cfqq); |
1919 | } | |
1920 | } | |
1921 | ||
1922 | /* | |
22e2c507 | 1923 | * Allocate cfq data structures associated with this request. |
1da177e4 | 1924 | */ |
22e2c507 | 1925 | static int |
165125e1 | 1926 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
1927 | { |
1928 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3b18152c | 1929 | struct task_struct *tsk = current; |
1da177e4 LT |
1930 | struct cfq_io_context *cic; |
1931 | const int rw = rq_data_dir(rq); | |
7749a8d4 | 1932 | const int is_sync = rq_is_sync(rq); |
22e2c507 | 1933 | struct cfq_queue *cfqq; |
1da177e4 LT |
1934 | unsigned long flags; |
1935 | ||
1936 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1937 | ||
e2d74ac0 | 1938 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 1939 | |
1da177e4 LT |
1940 | spin_lock_irqsave(q->queue_lock, flags); |
1941 | ||
22e2c507 JA |
1942 | if (!cic) |
1943 | goto queue_fail; | |
1944 | ||
91fac317 VT |
1945 | cfqq = cic_to_cfqq(cic, is_sync); |
1946 | if (!cfqq) { | |
1947 | cfqq = cfq_get_queue(cfqd, is_sync, tsk, gfp_mask); | |
1948 | ||
22e2c507 JA |
1949 | if (!cfqq) |
1950 | goto queue_fail; | |
1da177e4 | 1951 | |
91fac317 VT |
1952 | cic_set_cfqq(cic, cfqq, is_sync); |
1953 | } | |
1da177e4 LT |
1954 | |
1955 | cfqq->allocated[rw]++; | |
3b18152c | 1956 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 | 1957 | atomic_inc(&cfqq->ref); |
1da177e4 | 1958 | |
5e705374 | 1959 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 1960 | |
5e705374 JA |
1961 | rq->elevator_private = cic; |
1962 | rq->elevator_private2 = cfqq; | |
1963 | return 0; | |
1da177e4 | 1964 | |
22e2c507 JA |
1965 | queue_fail: |
1966 | if (cic) | |
1967 | put_io_context(cic->ioc); | |
89850f7e | 1968 | |
3b18152c | 1969 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1970 | spin_unlock_irqrestore(q->queue_lock, flags); |
1971 | return 1; | |
1972 | } | |
1973 | ||
65f27f38 | 1974 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 1975 | { |
65f27f38 DH |
1976 | struct cfq_data *cfqd = |
1977 | container_of(work, struct cfq_data, unplug_work); | |
165125e1 | 1978 | struct request_queue *q = cfqd->queue; |
22e2c507 JA |
1979 | unsigned long flags; |
1980 | ||
1981 | spin_lock_irqsave(q->queue_lock, flags); | |
dc72ef4a | 1982 | blk_start_queueing(q); |
22e2c507 JA |
1983 | spin_unlock_irqrestore(q->queue_lock, flags); |
1984 | } | |
1985 | ||
1986 | /* | |
1987 | * Timer running if the active_queue is currently idling inside its time slice | |
1988 | */ | |
1989 | static void cfq_idle_slice_timer(unsigned long data) | |
1990 | { | |
1991 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
1992 | struct cfq_queue *cfqq; | |
1993 | unsigned long flags; | |
3c6bd2f8 | 1994 | int timed_out = 1; |
22e2c507 JA |
1995 | |
1996 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1997 | ||
1998 | if ((cfqq = cfqd->active_queue) != NULL) { | |
3c6bd2f8 JA |
1999 | timed_out = 0; |
2000 | ||
22e2c507 JA |
2001 | /* |
2002 | * expired | |
2003 | */ | |
44f7c160 | 2004 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2005 | goto expire; |
2006 | ||
2007 | /* | |
2008 | * only expire and reinvoke request handler, if there are | |
2009 | * other queues with pending requests | |
2010 | */ | |
caaa5f9f | 2011 | if (!cfqd->busy_queues) |
22e2c507 | 2012 | goto out_cont; |
22e2c507 JA |
2013 | |
2014 | /* | |
2015 | * not expired and it has a request pending, let it dispatch | |
2016 | */ | |
dd67d051 | 2017 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) { |
3b18152c | 2018 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2019 | goto out_kick; |
2020 | } | |
2021 | } | |
2022 | expire: | |
6084cdda | 2023 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2024 | out_kick: |
3b18152c | 2025 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2026 | out_cont: |
2027 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2028 | } | |
2029 | ||
2030 | /* | |
2031 | * Timer running if an idle class queue is waiting for service | |
2032 | */ | |
2033 | static void cfq_idle_class_timer(unsigned long data) | |
2034 | { | |
2035 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2036 | unsigned long flags, end; | |
2037 | ||
2038 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2039 | ||
2040 | /* | |
2041 | * race with a non-idle queue, reset timer | |
2042 | */ | |
2043 | end = cfqd->last_end_request + CFQ_IDLE_GRACE; | |
ae818a38 JA |
2044 | if (!time_after_eq(jiffies, end)) |
2045 | mod_timer(&cfqd->idle_class_timer, end); | |
2046 | else | |
3b18152c | 2047 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2048 | |
2049 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2050 | } | |
2051 | ||
3b18152c JA |
2052 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2053 | { | |
2054 | del_timer_sync(&cfqd->idle_slice_timer); | |
2055 | del_timer_sync(&cfqd->idle_class_timer); | |
2056 | blk_sync_queue(cfqd->queue); | |
2057 | } | |
22e2c507 | 2058 | |
c2dea2d1 VT |
2059 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2060 | { | |
2061 | int i; | |
2062 | ||
2063 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2064 | if (cfqd->async_cfqq[0][i]) | |
2065 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2066 | if (cfqd->async_cfqq[1][i]) | |
2067 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
2068 | if (cfqd->async_idle_cfqq) | |
2069 | cfq_put_queue(cfqd->async_idle_cfqq); | |
2070 | } | |
2071 | } | |
2072 | ||
1da177e4 LT |
2073 | static void cfq_exit_queue(elevator_t *e) |
2074 | { | |
22e2c507 | 2075 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2076 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2077 | |
3b18152c | 2078 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2079 | |
d9ff4187 | 2080 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2081 | |
d9ff4187 | 2082 | if (cfqd->active_queue) |
6084cdda | 2083 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2084 | |
2085 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2086 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2087 | struct cfq_io_context, | |
2088 | queue_list); | |
89850f7e JA |
2089 | |
2090 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2091 | } |
e2d74ac0 | 2092 | |
c2dea2d1 | 2093 | cfq_put_async_queues(cfqd); |
15c31be4 | 2094 | |
d9ff4187 | 2095 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2096 | |
2097 | cfq_shutdown_timer_wq(cfqd); | |
2098 | ||
a90d742e | 2099 | kfree(cfqd); |
1da177e4 LT |
2100 | } |
2101 | ||
165125e1 | 2102 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2103 | { |
2104 | struct cfq_data *cfqd; | |
1da177e4 | 2105 | |
94f6030c | 2106 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2107 | if (!cfqd) |
bc1c1169 | 2108 | return NULL; |
1da177e4 | 2109 | |
cc09e299 | 2110 | cfqd->service_tree = CFQ_RB_ROOT; |
d9ff4187 | 2111 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2112 | |
1da177e4 | 2113 | cfqd->queue = q; |
1da177e4 | 2114 | |
22e2c507 JA |
2115 | init_timer(&cfqd->idle_slice_timer); |
2116 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2117 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2118 | ||
2119 | init_timer(&cfqd->idle_class_timer); | |
2120 | cfqd->idle_class_timer.function = cfq_idle_class_timer; | |
2121 | cfqd->idle_class_timer.data = (unsigned long) cfqd; | |
2122 | ||
65f27f38 | 2123 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2124 | |
1da177e4 | 2125 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2126 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2127 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2128 | cfqd->cfq_back_max = cfq_back_max; |
2129 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2130 | cfqd->cfq_slice[0] = cfq_slice_async; |
2131 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2132 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2133 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2134 | |
bc1c1169 | 2135 | return cfqd; |
1da177e4 LT |
2136 | } |
2137 | ||
2138 | static void cfq_slab_kill(void) | |
2139 | { | |
1da177e4 LT |
2140 | if (cfq_pool) |
2141 | kmem_cache_destroy(cfq_pool); | |
2142 | if (cfq_ioc_pool) | |
2143 | kmem_cache_destroy(cfq_ioc_pool); | |
2144 | } | |
2145 | ||
2146 | static int __init cfq_slab_setup(void) | |
2147 | { | |
0a31bd5f | 2148 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
2149 | if (!cfq_pool) |
2150 | goto fail; | |
2151 | ||
0a31bd5f | 2152 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
2153 | if (!cfq_ioc_pool) |
2154 | goto fail; | |
2155 | ||
2156 | return 0; | |
2157 | fail: | |
2158 | cfq_slab_kill(); | |
2159 | return -ENOMEM; | |
2160 | } | |
2161 | ||
1da177e4 LT |
2162 | /* |
2163 | * sysfs parts below --> | |
2164 | */ | |
1da177e4 LT |
2165 | static ssize_t |
2166 | cfq_var_show(unsigned int var, char *page) | |
2167 | { | |
2168 | return sprintf(page, "%d\n", var); | |
2169 | } | |
2170 | ||
2171 | static ssize_t | |
2172 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2173 | { | |
2174 | char *p = (char *) page; | |
2175 | ||
2176 | *var = simple_strtoul(p, &p, 10); | |
2177 | return count; | |
2178 | } | |
2179 | ||
1da177e4 | 2180 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2181 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2182 | { \ |
3d1ab40f | 2183 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2184 | unsigned int __data = __VAR; \ |
2185 | if (__CONV) \ | |
2186 | __data = jiffies_to_msecs(__data); \ | |
2187 | return cfq_var_show(__data, (page)); \ | |
2188 | } | |
2189 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
2190 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2191 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2192 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2193 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2194 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2195 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2196 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2197 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2198 | #undef SHOW_FUNCTION |
2199 | ||
2200 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2201 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2202 | { \ |
3d1ab40f | 2203 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2204 | unsigned int __data; \ |
2205 | int ret = cfq_var_store(&__data, (page), count); \ | |
2206 | if (__data < (MIN)) \ | |
2207 | __data = (MIN); \ | |
2208 | else if (__data > (MAX)) \ | |
2209 | __data = (MAX); \ | |
2210 | if (__CONV) \ | |
2211 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2212 | else \ | |
2213 | *(__PTR) = __data; \ | |
2214 | return ret; \ | |
2215 | } | |
2216 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
22e2c507 JA |
2217 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2218 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2219 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2220 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2221 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2222 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2223 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2224 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2225 | #undef STORE_FUNCTION |
2226 | ||
e572ec7e AV |
2227 | #define CFQ_ATTR(name) \ |
2228 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2229 | ||
2230 | static struct elv_fs_entry cfq_attrs[] = { | |
2231 | CFQ_ATTR(quantum), | |
e572ec7e AV |
2232 | CFQ_ATTR(fifo_expire_sync), |
2233 | CFQ_ATTR(fifo_expire_async), | |
2234 | CFQ_ATTR(back_seek_max), | |
2235 | CFQ_ATTR(back_seek_penalty), | |
2236 | CFQ_ATTR(slice_sync), | |
2237 | CFQ_ATTR(slice_async), | |
2238 | CFQ_ATTR(slice_async_rq), | |
2239 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2240 | __ATTR_NULL |
1da177e4 LT |
2241 | }; |
2242 | ||
1da177e4 LT |
2243 | static struct elevator_type iosched_cfq = { |
2244 | .ops = { | |
2245 | .elevator_merge_fn = cfq_merge, | |
2246 | .elevator_merged_fn = cfq_merged_request, | |
2247 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 2248 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 2249 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2250 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2251 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2252 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2253 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2254 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
2255 | .elevator_former_req_fn = elv_rb_former_request, |
2256 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
2257 | .elevator_set_req_fn = cfq_set_request, |
2258 | .elevator_put_req_fn = cfq_put_request, | |
2259 | .elevator_may_queue_fn = cfq_may_queue, | |
2260 | .elevator_init_fn = cfq_init_queue, | |
2261 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 2262 | .trim = cfq_free_io_context, |
1da177e4 | 2263 | }, |
3d1ab40f | 2264 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2265 | .elevator_name = "cfq", |
2266 | .elevator_owner = THIS_MODULE, | |
2267 | }; | |
2268 | ||
2269 | static int __init cfq_init(void) | |
2270 | { | |
2271 | int ret; | |
2272 | ||
22e2c507 JA |
2273 | /* |
2274 | * could be 0 on HZ < 1000 setups | |
2275 | */ | |
2276 | if (!cfq_slice_async) | |
2277 | cfq_slice_async = 1; | |
2278 | if (!cfq_slice_idle) | |
2279 | cfq_slice_idle = 1; | |
2280 | ||
1da177e4 LT |
2281 | if (cfq_slab_setup()) |
2282 | return -ENOMEM; | |
2283 | ||
2284 | ret = elv_register(&iosched_cfq); | |
22e2c507 JA |
2285 | if (ret) |
2286 | cfq_slab_kill(); | |
1da177e4 | 2287 | |
1da177e4 LT |
2288 | return ret; |
2289 | } | |
2290 | ||
2291 | static void __exit cfq_exit(void) | |
2292 | { | |
6e9a4738 | 2293 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 2294 | elv_unregister(&iosched_cfq); |
334e94de | 2295 | ioc_gone = &all_gone; |
fba82272 OH |
2296 | /* ioc_gone's update must be visible before reading ioc_count */ |
2297 | smp_wmb(); | |
4050cf16 | 2298 | if (elv_ioc_count_read(ioc_count)) |
fba82272 | 2299 | wait_for_completion(ioc_gone); |
334e94de | 2300 | synchronize_rcu(); |
83521d3e | 2301 | cfq_slab_kill(); |
1da177e4 LT |
2302 | } |
2303 | ||
2304 | module_init(cfq_init); | |
2305 | module_exit(cfq_exit); | |
2306 | ||
2307 | MODULE_AUTHOR("Jens Axboe"); | |
2308 | MODULE_LICENSE("GPL"); | |
2309 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |