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 | 28 | /* |
0871714e | 29 | * offset from end of service tree |
d9e7620e | 30 | */ |
0871714e | 31 | #define CFQ_IDLE_DELAY (HZ / 5) |
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 | |
6d048f53 | 101 | sector_t last_position; |
22e2c507 | 102 | unsigned long last_end_request; |
1da177e4 | 103 | |
1da177e4 LT |
104 | /* |
105 | * tunables, see top of file | |
106 | */ | |
107 | unsigned int cfq_quantum; | |
22e2c507 | 108 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
109 | unsigned int cfq_back_penalty; |
110 | unsigned int cfq_back_max; | |
22e2c507 JA |
111 | unsigned int cfq_slice[2]; |
112 | unsigned int cfq_slice_async_rq; | |
113 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
114 | |
115 | struct list_head cic_list; | |
1da177e4 LT |
116 | }; |
117 | ||
22e2c507 JA |
118 | /* |
119 | * Per process-grouping structure | |
120 | */ | |
1da177e4 LT |
121 | struct cfq_queue { |
122 | /* reference count */ | |
123 | atomic_t ref; | |
124 | /* parent cfq_data */ | |
125 | struct cfq_data *cfqd; | |
d9e7620e JA |
126 | /* service_tree member */ |
127 | struct rb_node rb_node; | |
128 | /* service_tree key */ | |
129 | unsigned long rb_key; | |
1da177e4 LT |
130 | /* sorted list of pending requests */ |
131 | struct rb_root sort_list; | |
132 | /* if fifo isn't expired, next request to serve */ | |
5e705374 | 133 | struct request *next_rq; |
1da177e4 LT |
134 | /* requests queued in sort_list */ |
135 | int queued[2]; | |
136 | /* currently allocated requests */ | |
137 | int allocated[2]; | |
374f84ac JA |
138 | /* pending metadata requests */ |
139 | int meta_pending; | |
1da177e4 | 140 | /* fifo list of requests in sort_list */ |
22e2c507 | 141 | struct list_head fifo; |
1da177e4 | 142 | |
22e2c507 | 143 | unsigned long slice_end; |
c5b680f3 | 144 | long slice_resid; |
1da177e4 | 145 | |
6d048f53 JA |
146 | /* number of requests that are on the dispatch list or inside driver */ |
147 | int dispatched; | |
22e2c507 JA |
148 | |
149 | /* io prio of this group */ | |
150 | unsigned short ioprio, org_ioprio; | |
151 | unsigned short ioprio_class, org_ioprio_class; | |
152 | ||
3b18152c JA |
153 | /* various state flags, see below */ |
154 | unsigned int flags; | |
1da177e4 LT |
155 | }; |
156 | ||
3b18152c | 157 | enum cfqq_state_flags { |
b0b8d749 JA |
158 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
159 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
160 | CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ | |
161 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ | |
162 | CFQ_CFQQ_FLAG_must_dispatch, /* must dispatch, even if expired */ | |
163 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ | |
164 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
165 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
166 | CFQ_CFQQ_FLAG_queue_new, /* queue never been serviced */ | |
44f7c160 | 167 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 168 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
3b18152c JA |
169 | }; |
170 | ||
171 | #define CFQ_CFQQ_FNS(name) \ | |
172 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
173 | { \ | |
174 | cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
175 | } \ | |
176 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
177 | { \ | |
178 | cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
179 | } \ | |
180 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
181 | { \ | |
182 | return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
183 | } | |
184 | ||
185 | CFQ_CFQQ_FNS(on_rr); | |
186 | CFQ_CFQQ_FNS(wait_request); | |
187 | CFQ_CFQQ_FNS(must_alloc); | |
188 | CFQ_CFQQ_FNS(must_alloc_slice); | |
189 | CFQ_CFQQ_FNS(must_dispatch); | |
190 | CFQ_CFQQ_FNS(fifo_expire); | |
191 | CFQ_CFQQ_FNS(idle_window); | |
192 | CFQ_CFQQ_FNS(prio_changed); | |
53b03744 | 193 | CFQ_CFQQ_FNS(queue_new); |
44f7c160 | 194 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 195 | CFQ_CFQQ_FNS(sync); |
3b18152c JA |
196 | #undef CFQ_CFQQ_FNS |
197 | ||
165125e1 | 198 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
91fac317 | 199 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, int, |
fd0928df | 200 | struct io_context *, gfp_t); |
4ac845a2 | 201 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
202 | struct io_context *); |
203 | ||
204 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, | |
205 | int is_sync) | |
206 | { | |
207 | return cic->cfqq[!!is_sync]; | |
208 | } | |
209 | ||
210 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
211 | struct cfq_queue *cfqq, int is_sync) | |
212 | { | |
213 | cic->cfqq[!!is_sync] = cfqq; | |
214 | } | |
215 | ||
216 | /* | |
217 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
218 | * set (in which case it could also be direct WRITE). | |
219 | */ | |
220 | static inline int cfq_bio_sync(struct bio *bio) | |
221 | { | |
222 | if (bio_data_dir(bio) == READ || bio_sync(bio)) | |
223 | return 1; | |
224 | ||
225 | return 0; | |
226 | } | |
1da177e4 | 227 | |
99f95e52 AM |
228 | /* |
229 | * scheduler run of queue, if there are requests pending and no one in the | |
230 | * driver that will restart queueing | |
231 | */ | |
232 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
233 | { | |
7b14e3b5 | 234 | if (cfqd->busy_queues) |
99f95e52 AM |
235 | kblockd_schedule_work(&cfqd->unplug_work); |
236 | } | |
237 | ||
165125e1 | 238 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
239 | { |
240 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
241 | ||
b4878f24 | 242 | return !cfqd->busy_queues; |
99f95e52 AM |
243 | } |
244 | ||
44f7c160 JA |
245 | /* |
246 | * Scale schedule slice based on io priority. Use the sync time slice only | |
247 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
248 | * io only, should not get full sync slice length. | |
249 | */ | |
d9e7620e JA |
250 | static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync, |
251 | unsigned short prio) | |
44f7c160 | 252 | { |
d9e7620e | 253 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 254 | |
d9e7620e JA |
255 | WARN_ON(prio >= IOPRIO_BE_NR); |
256 | ||
257 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
258 | } | |
44f7c160 | 259 | |
d9e7620e JA |
260 | static inline int |
261 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
262 | { | |
263 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
264 | } |
265 | ||
266 | static inline void | |
267 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
268 | { | |
269 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
270 | } | |
271 | ||
272 | /* | |
273 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
274 | * isn't valid until the first request from the dispatch is activated | |
275 | * and the slice time set. | |
276 | */ | |
277 | static inline int cfq_slice_used(struct cfq_queue *cfqq) | |
278 | { | |
279 | if (cfq_cfqq_slice_new(cfqq)) | |
280 | return 0; | |
281 | if (time_before(jiffies, cfqq->slice_end)) | |
282 | return 0; | |
283 | ||
284 | return 1; | |
285 | } | |
286 | ||
1da177e4 | 287 | /* |
5e705374 | 288 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 289 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 290 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 291 | */ |
5e705374 JA |
292 | static struct request * |
293 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
1da177e4 LT |
294 | { |
295 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 296 | unsigned long back_max; |
e8a99053 AM |
297 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
298 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
299 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 300 | |
5e705374 JA |
301 | if (rq1 == NULL || rq1 == rq2) |
302 | return rq2; | |
303 | if (rq2 == NULL) | |
304 | return rq1; | |
9c2c38a1 | 305 | |
5e705374 JA |
306 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
307 | return rq1; | |
308 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
309 | return rq2; | |
374f84ac JA |
310 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
311 | return rq1; | |
312 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
313 | return rq2; | |
1da177e4 | 314 | |
5e705374 JA |
315 | s1 = rq1->sector; |
316 | s2 = rq2->sector; | |
1da177e4 | 317 | |
6d048f53 | 318 | last = cfqd->last_position; |
1da177e4 | 319 | |
1da177e4 LT |
320 | /* |
321 | * by definition, 1KiB is 2 sectors | |
322 | */ | |
323 | back_max = cfqd->cfq_back_max * 2; | |
324 | ||
325 | /* | |
326 | * Strict one way elevator _except_ in the case where we allow | |
327 | * short backward seeks which are biased as twice the cost of a | |
328 | * similar forward seek. | |
329 | */ | |
330 | if (s1 >= last) | |
331 | d1 = s1 - last; | |
332 | else if (s1 + back_max >= last) | |
333 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
334 | else | |
e8a99053 | 335 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
336 | |
337 | if (s2 >= last) | |
338 | d2 = s2 - last; | |
339 | else if (s2 + back_max >= last) | |
340 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
341 | else | |
e8a99053 | 342 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
343 | |
344 | /* Found required data */ | |
e8a99053 AM |
345 | |
346 | /* | |
347 | * By doing switch() on the bit mask "wrap" we avoid having to | |
348 | * check two variables for all permutations: --> faster! | |
349 | */ | |
350 | switch (wrap) { | |
5e705374 | 351 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 352 | if (d1 < d2) |
5e705374 | 353 | return rq1; |
e8a99053 | 354 | else if (d2 < d1) |
5e705374 | 355 | return rq2; |
e8a99053 AM |
356 | else { |
357 | if (s1 >= s2) | |
5e705374 | 358 | return rq1; |
e8a99053 | 359 | else |
5e705374 | 360 | return rq2; |
e8a99053 | 361 | } |
1da177e4 | 362 | |
e8a99053 | 363 | case CFQ_RQ2_WRAP: |
5e705374 | 364 | return rq1; |
e8a99053 | 365 | case CFQ_RQ1_WRAP: |
5e705374 JA |
366 | return rq2; |
367 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
368 | default: |
369 | /* | |
370 | * Since both rqs are wrapped, | |
371 | * start with the one that's further behind head | |
372 | * (--> only *one* back seek required), | |
373 | * since back seek takes more time than forward. | |
374 | */ | |
375 | if (s1 <= s2) | |
5e705374 | 376 | return rq1; |
1da177e4 | 377 | else |
5e705374 | 378 | return rq2; |
1da177e4 LT |
379 | } |
380 | } | |
381 | ||
498d3aa2 JA |
382 | /* |
383 | * The below is leftmost cache rbtree addon | |
384 | */ | |
0871714e | 385 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 JA |
386 | { |
387 | if (!root->left) | |
388 | root->left = rb_first(&root->rb); | |
389 | ||
0871714e JA |
390 | if (root->left) |
391 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
392 | ||
393 | return NULL; | |
cc09e299 JA |
394 | } |
395 | ||
396 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) | |
397 | { | |
398 | if (root->left == n) | |
399 | root->left = NULL; | |
400 | ||
401 | rb_erase(n, &root->rb); | |
402 | RB_CLEAR_NODE(n); | |
403 | } | |
404 | ||
1da177e4 LT |
405 | /* |
406 | * would be nice to take fifo expire time into account as well | |
407 | */ | |
5e705374 JA |
408 | static struct request * |
409 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
410 | struct request *last) | |
1da177e4 | 411 | { |
21183b07 JA |
412 | struct rb_node *rbnext = rb_next(&last->rb_node); |
413 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 414 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 415 | |
21183b07 | 416 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
417 | |
418 | if (rbprev) | |
5e705374 | 419 | prev = rb_entry_rq(rbprev); |
1da177e4 | 420 | |
21183b07 | 421 | if (rbnext) |
5e705374 | 422 | next = rb_entry_rq(rbnext); |
21183b07 JA |
423 | else { |
424 | rbnext = rb_first(&cfqq->sort_list); | |
425 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 426 | next = rb_entry_rq(rbnext); |
21183b07 | 427 | } |
1da177e4 | 428 | |
21183b07 | 429 | return cfq_choose_req(cfqd, next, prev); |
1da177e4 LT |
430 | } |
431 | ||
d9e7620e JA |
432 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
433 | struct cfq_queue *cfqq) | |
1da177e4 | 434 | { |
d9e7620e JA |
435 | /* |
436 | * just an approximation, should be ok. | |
437 | */ | |
67e6b49e JA |
438 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
439 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
440 | } |
441 | ||
498d3aa2 JA |
442 | /* |
443 | * The cfqd->service_tree holds all pending cfq_queue's that have | |
444 | * requests waiting to be processed. It is sorted in the order that | |
445 | * we will service the queues. | |
446 | */ | |
d9e7620e | 447 | static void cfq_service_tree_add(struct cfq_data *cfqd, |
edd75ffd | 448 | struct cfq_queue *cfqq, int add_front) |
d9e7620e | 449 | { |
0871714e JA |
450 | struct rb_node **p, *parent; |
451 | struct cfq_queue *__cfqq; | |
d9e7620e | 452 | unsigned long rb_key; |
498d3aa2 | 453 | int left; |
d9e7620e | 454 | |
0871714e JA |
455 | if (cfq_class_idle(cfqq)) { |
456 | rb_key = CFQ_IDLE_DELAY; | |
457 | parent = rb_last(&cfqd->service_tree.rb); | |
458 | if (parent && parent != &cfqq->rb_node) { | |
459 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
460 | rb_key += __cfqq->rb_key; | |
461 | } else | |
462 | rb_key += jiffies; | |
463 | } else if (!add_front) { | |
edd75ffd JA |
464 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
465 | rb_key += cfqq->slice_resid; | |
466 | cfqq->slice_resid = 0; | |
467 | } else | |
468 | rb_key = 0; | |
1da177e4 | 469 | |
d9e7620e | 470 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 471 | /* |
d9e7620e | 472 | * same position, nothing more to do |
99f9628a | 473 | */ |
d9e7620e JA |
474 | if (rb_key == cfqq->rb_key) |
475 | return; | |
1da177e4 | 476 | |
cc09e299 | 477 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
1da177e4 | 478 | } |
d9e7620e | 479 | |
498d3aa2 | 480 | left = 1; |
0871714e JA |
481 | parent = NULL; |
482 | p = &cfqd->service_tree.rb.rb_node; | |
d9e7620e | 483 | while (*p) { |
67060e37 | 484 | struct rb_node **n; |
cc09e299 | 485 | |
d9e7620e JA |
486 | parent = *p; |
487 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
488 | ||
0c534e0a JA |
489 | /* |
490 | * sort RT queues first, we always want to give | |
67060e37 JA |
491 | * preference to them. IDLE queues goes to the back. |
492 | * after that, sort on the next service time. | |
0c534e0a JA |
493 | */ |
494 | if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) | |
67060e37 | 495 | n = &(*p)->rb_left; |
0c534e0a | 496 | else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) |
67060e37 JA |
497 | n = &(*p)->rb_right; |
498 | else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) | |
499 | n = &(*p)->rb_left; | |
500 | else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) | |
501 | n = &(*p)->rb_right; | |
0c534e0a | 502 | else if (rb_key < __cfqq->rb_key) |
67060e37 JA |
503 | n = &(*p)->rb_left; |
504 | else | |
505 | n = &(*p)->rb_right; | |
506 | ||
507 | if (n == &(*p)->rb_right) | |
cc09e299 | 508 | left = 0; |
67060e37 JA |
509 | |
510 | p = n; | |
d9e7620e JA |
511 | } |
512 | ||
cc09e299 JA |
513 | if (left) |
514 | cfqd->service_tree.left = &cfqq->rb_node; | |
515 | ||
d9e7620e JA |
516 | cfqq->rb_key = rb_key; |
517 | rb_link_node(&cfqq->rb_node, parent, p); | |
cc09e299 | 518 | rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); |
1da177e4 LT |
519 | } |
520 | ||
498d3aa2 JA |
521 | /* |
522 | * Update cfqq's position in the service tree. | |
523 | */ | |
edd75ffd | 524 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 525 | { |
6d048f53 JA |
526 | /* |
527 | * Resorting requires the cfqq to be on the RR list already. | |
528 | */ | |
498d3aa2 | 529 | if (cfq_cfqq_on_rr(cfqq)) |
edd75ffd | 530 | cfq_service_tree_add(cfqd, cfqq, 0); |
6d048f53 JA |
531 | } |
532 | ||
1da177e4 LT |
533 | /* |
534 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 535 | * the pending list according to last request service |
1da177e4 | 536 | */ |
febffd61 | 537 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 538 | { |
3b18152c JA |
539 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
540 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
541 | cfqd->busy_queues++; |
542 | ||
edd75ffd | 543 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
544 | } |
545 | ||
498d3aa2 JA |
546 | /* |
547 | * Called when the cfqq no longer has requests pending, remove it from | |
548 | * the service tree. | |
549 | */ | |
febffd61 | 550 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 551 | { |
3b18152c JA |
552 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
553 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 554 | |
cc09e299 JA |
555 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) |
556 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); | |
d9e7620e | 557 | |
1da177e4 LT |
558 | BUG_ON(!cfqd->busy_queues); |
559 | cfqd->busy_queues--; | |
560 | } | |
561 | ||
562 | /* | |
563 | * rb tree support functions | |
564 | */ | |
febffd61 | 565 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 566 | { |
5e705374 | 567 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 568 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 569 | const int sync = rq_is_sync(rq); |
1da177e4 | 570 | |
b4878f24 JA |
571 | BUG_ON(!cfqq->queued[sync]); |
572 | cfqq->queued[sync]--; | |
1da177e4 | 573 | |
5e705374 | 574 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 575 | |
dd67d051 | 576 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 577 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
578 | } |
579 | ||
5e705374 | 580 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 581 | { |
5e705374 | 582 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 583 | struct cfq_data *cfqd = cfqq->cfqd; |
21183b07 | 584 | struct request *__alias; |
1da177e4 | 585 | |
5380a101 | 586 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
587 | |
588 | /* | |
589 | * looks a little odd, but the first insert might return an alias. | |
590 | * if that happens, put the alias on the dispatch list | |
591 | */ | |
21183b07 | 592 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 593 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
594 | |
595 | if (!cfq_cfqq_on_rr(cfqq)) | |
596 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
597 | |
598 | /* | |
599 | * check if this request is a better next-serve candidate | |
600 | */ | |
601 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); | |
602 | BUG_ON(!cfqq->next_rq); | |
1da177e4 LT |
603 | } |
604 | ||
febffd61 | 605 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 606 | { |
5380a101 JA |
607 | elv_rb_del(&cfqq->sort_list, rq); |
608 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 609 | cfq_add_rq_rb(rq); |
1da177e4 LT |
610 | } |
611 | ||
206dc69b JA |
612 | static struct request * |
613 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 614 | { |
206dc69b | 615 | struct task_struct *tsk = current; |
91fac317 | 616 | struct cfq_io_context *cic; |
206dc69b | 617 | struct cfq_queue *cfqq; |
1da177e4 | 618 | |
4ac845a2 | 619 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
620 | if (!cic) |
621 | return NULL; | |
622 | ||
623 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
624 | if (cfqq) { |
625 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
626 | ||
21183b07 | 627 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 628 | } |
1da177e4 | 629 | |
1da177e4 LT |
630 | return NULL; |
631 | } | |
632 | ||
165125e1 | 633 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 634 | { |
22e2c507 | 635 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 636 | |
b4878f24 | 637 | cfqd->rq_in_driver++; |
25776e35 JA |
638 | |
639 | /* | |
640 | * If the depth is larger 1, it really could be queueing. But lets | |
641 | * make the mark a little higher - idling could still be good for | |
642 | * low queueing, and a low queueing number could also just indicate | |
643 | * a SCSI mid layer like behaviour where limit+1 is often seen. | |
644 | */ | |
645 | if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) | |
646 | cfqd->hw_tag = 1; | |
6d048f53 JA |
647 | |
648 | cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors; | |
1da177e4 LT |
649 | } |
650 | ||
165125e1 | 651 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 652 | { |
b4878f24 JA |
653 | struct cfq_data *cfqd = q->elevator->elevator_data; |
654 | ||
655 | WARN_ON(!cfqd->rq_in_driver); | |
656 | cfqd->rq_in_driver--; | |
1da177e4 LT |
657 | } |
658 | ||
b4878f24 | 659 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 660 | { |
5e705374 | 661 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 662 | |
5e705374 JA |
663 | if (cfqq->next_rq == rq) |
664 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 665 | |
b4878f24 | 666 | list_del_init(&rq->queuelist); |
5e705374 | 667 | cfq_del_rq_rb(rq); |
374f84ac JA |
668 | |
669 | if (rq_is_meta(rq)) { | |
670 | WARN_ON(!cfqq->meta_pending); | |
671 | cfqq->meta_pending--; | |
672 | } | |
1da177e4 LT |
673 | } |
674 | ||
165125e1 JA |
675 | static int cfq_merge(struct request_queue *q, struct request **req, |
676 | struct bio *bio) | |
1da177e4 LT |
677 | { |
678 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
679 | struct request *__rq; | |
1da177e4 | 680 | |
206dc69b | 681 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 682 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
683 | *req = __rq; |
684 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
685 | } |
686 | ||
687 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
688 | } |
689 | ||
165125e1 | 690 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 691 | int type) |
1da177e4 | 692 | { |
21183b07 | 693 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 694 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 695 | |
5e705374 | 696 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 697 | } |
1da177e4 LT |
698 | } |
699 | ||
700 | static void | |
165125e1 | 701 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
702 | struct request *next) |
703 | { | |
22e2c507 JA |
704 | /* |
705 | * reposition in fifo if next is older than rq | |
706 | */ | |
707 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
708 | time_before(next->start_time, rq->start_time)) | |
709 | list_move(&rq->queuelist, &next->queuelist); | |
710 | ||
b4878f24 | 711 | cfq_remove_request(next); |
22e2c507 JA |
712 | } |
713 | ||
165125e1 | 714 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
715 | struct bio *bio) |
716 | { | |
717 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 718 | struct cfq_io_context *cic; |
da775265 | 719 | struct cfq_queue *cfqq; |
da775265 JA |
720 | |
721 | /* | |
ec8acb69 | 722 | * Disallow merge of a sync bio into an async request. |
da775265 | 723 | */ |
91fac317 | 724 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
da775265 JA |
725 | return 0; |
726 | ||
727 | /* | |
719d3402 JA |
728 | * Lookup the cfqq that this bio will be queued with. Allow |
729 | * merge only if rq is queued there. | |
da775265 | 730 | */ |
4ac845a2 | 731 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 VT |
732 | if (!cic) |
733 | return 0; | |
719d3402 | 734 | |
91fac317 | 735 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
719d3402 JA |
736 | if (cfqq == RQ_CFQQ(rq)) |
737 | return 1; | |
da775265 | 738 | |
ec8acb69 | 739 | return 0; |
da775265 JA |
740 | } |
741 | ||
febffd61 JA |
742 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
743 | struct cfq_queue *cfqq) | |
22e2c507 JA |
744 | { |
745 | if (cfqq) { | |
22e2c507 | 746 | cfqq->slice_end = 0; |
3b18152c JA |
747 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
748 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 749 | cfq_mark_cfqq_slice_new(cfqq); |
1afba045 | 750 | cfq_clear_cfqq_queue_new(cfqq); |
22e2c507 JA |
751 | } |
752 | ||
753 | cfqd->active_queue = cfqq; | |
754 | } | |
755 | ||
7b14e3b5 JA |
756 | /* |
757 | * current cfqq expired its slice (or was too idle), select new one | |
758 | */ | |
759 | static void | |
760 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
6084cdda | 761 | int timed_out) |
7b14e3b5 | 762 | { |
7b14e3b5 JA |
763 | if (cfq_cfqq_wait_request(cfqq)) |
764 | del_timer(&cfqd->idle_slice_timer); | |
765 | ||
7b14e3b5 JA |
766 | cfq_clear_cfqq_must_dispatch(cfqq); |
767 | cfq_clear_cfqq_wait_request(cfqq); | |
768 | ||
769 | /* | |
6084cdda | 770 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 771 | */ |
3c6bd2f8 | 772 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) |
c5b680f3 | 773 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b14e3b5 | 774 | |
edd75ffd | 775 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
776 | |
777 | if (cfqq == cfqd->active_queue) | |
778 | cfqd->active_queue = NULL; | |
779 | ||
780 | if (cfqd->active_cic) { | |
781 | put_io_context(cfqd->active_cic->ioc); | |
782 | cfqd->active_cic = NULL; | |
783 | } | |
7b14e3b5 JA |
784 | } |
785 | ||
6084cdda | 786 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out) |
7b14e3b5 JA |
787 | { |
788 | struct cfq_queue *cfqq = cfqd->active_queue; | |
789 | ||
790 | if (cfqq) | |
6084cdda | 791 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
792 | } |
793 | ||
498d3aa2 JA |
794 | /* |
795 | * Get next queue for service. Unless we have a queue preemption, | |
796 | * we'll simply select the first cfqq in the service tree. | |
797 | */ | |
6d048f53 | 798 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 799 | { |
edd75ffd JA |
800 | if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) |
801 | return NULL; | |
d9e7620e | 802 | |
0871714e | 803 | return cfq_rb_first(&cfqd->service_tree); |
6d048f53 JA |
804 | } |
805 | ||
498d3aa2 JA |
806 | /* |
807 | * Get and set a new active queue for service. | |
808 | */ | |
6d048f53 JA |
809 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) |
810 | { | |
811 | struct cfq_queue *cfqq; | |
812 | ||
d9e7620e | 813 | cfqq = cfq_get_next_queue(cfqd); |
22e2c507 | 814 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 815 | return cfqq; |
22e2c507 JA |
816 | } |
817 | ||
d9e7620e JA |
818 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
819 | struct request *rq) | |
820 | { | |
821 | if (rq->sector >= cfqd->last_position) | |
822 | return rq->sector - cfqd->last_position; | |
823 | else | |
824 | return cfqd->last_position - rq->sector; | |
825 | } | |
826 | ||
6d048f53 JA |
827 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) |
828 | { | |
829 | struct cfq_io_context *cic = cfqd->active_cic; | |
830 | ||
831 | if (!sample_valid(cic->seek_samples)) | |
832 | return 0; | |
833 | ||
834 | return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean; | |
835 | } | |
836 | ||
d9e7620e JA |
837 | static int cfq_close_cooperator(struct cfq_data *cfq_data, |
838 | struct cfq_queue *cfqq) | |
6d048f53 | 839 | { |
6d048f53 | 840 | /* |
d9e7620e JA |
841 | * We should notice if some of the queues are cooperating, eg |
842 | * working closely on the same area of the disk. In that case, | |
843 | * we can group them together and don't waste time idling. | |
6d048f53 | 844 | */ |
d9e7620e | 845 | return 0; |
6d048f53 JA |
846 | } |
847 | ||
848 | #define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024)) | |
caaa5f9f | 849 | |
6d048f53 | 850 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 851 | { |
1792669c | 852 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 853 | struct cfq_io_context *cic; |
7b14e3b5 JA |
854 | unsigned long sl; |
855 | ||
dd67d051 | 856 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 857 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
858 | |
859 | /* | |
860 | * idle is disabled, either manually or by past process history | |
861 | */ | |
6d048f53 JA |
862 | if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
863 | return; | |
864 | ||
22e2c507 JA |
865 | /* |
866 | * task has exited, don't wait | |
867 | */ | |
206dc69b | 868 | cic = cfqd->active_cic; |
66dac98e | 869 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
870 | return; |
871 | ||
872 | /* | |
873 | * See if this prio level has a good candidate | |
874 | */ | |
1afba045 JA |
875 | if (cfq_close_cooperator(cfqd, cfqq) && |
876 | (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2)) | |
6d048f53 | 877 | return; |
22e2c507 | 878 | |
3b18152c JA |
879 | cfq_mark_cfqq_must_dispatch(cfqq); |
880 | cfq_mark_cfqq_wait_request(cfqq); | |
22e2c507 | 881 | |
206dc69b JA |
882 | /* |
883 | * we don't want to idle for seeks, but we do want to allow | |
884 | * fair distribution of slice time for a process doing back-to-back | |
885 | * seeks. so allow a little bit of time for him to submit a new rq | |
886 | */ | |
6d048f53 | 887 | sl = cfqd->cfq_slice_idle; |
caaa5f9f | 888 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
d9e7620e | 889 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
206dc69b | 890 | |
7b14e3b5 | 891 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
1da177e4 LT |
892 | } |
893 | ||
498d3aa2 JA |
894 | /* |
895 | * Move request from internal lists to the request queue dispatch list. | |
896 | */ | |
165125e1 | 897 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 898 | { |
3ed9a296 | 899 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 900 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 901 | |
5380a101 | 902 | cfq_remove_request(rq); |
6d048f53 | 903 | cfqq->dispatched++; |
5380a101 | 904 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
905 | |
906 | if (cfq_cfqq_sync(cfqq)) | |
907 | cfqd->sync_flight++; | |
1da177e4 LT |
908 | } |
909 | ||
910 | /* | |
911 | * return expired entry, or NULL to just start from scratch in rbtree | |
912 | */ | |
febffd61 | 913 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 LT |
914 | { |
915 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 916 | struct request *rq; |
89850f7e | 917 | int fifo; |
1da177e4 | 918 | |
3b18152c | 919 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 920 | return NULL; |
cb887411 JA |
921 | |
922 | cfq_mark_cfqq_fifo_expire(cfqq); | |
923 | ||
89850f7e JA |
924 | if (list_empty(&cfqq->fifo)) |
925 | return NULL; | |
1da177e4 | 926 | |
6d048f53 | 927 | fifo = cfq_cfqq_sync(cfqq); |
89850f7e | 928 | rq = rq_entry_fifo(cfqq->fifo.next); |
1da177e4 | 929 | |
6d048f53 JA |
930 | if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) |
931 | return NULL; | |
1da177e4 | 932 | |
6d048f53 | 933 | return rq; |
1da177e4 LT |
934 | } |
935 | ||
22e2c507 JA |
936 | static inline int |
937 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
938 | { | |
939 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 940 | |
22e2c507 | 941 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 942 | |
22e2c507 | 943 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
944 | } |
945 | ||
22e2c507 | 946 | /* |
498d3aa2 JA |
947 | * Select a queue for service. If we have a current active queue, |
948 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 949 | */ |
1b5ed5e1 | 950 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 951 | { |
1da177e4 | 952 | struct cfq_queue *cfqq; |
1da177e4 | 953 | |
22e2c507 JA |
954 | cfqq = cfqd->active_queue; |
955 | if (!cfqq) | |
956 | goto new_queue; | |
1da177e4 | 957 | |
22e2c507 | 958 | /* |
6d048f53 | 959 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 960 | */ |
6d048f53 | 961 | if (cfq_slice_used(cfqq)) |
3b18152c | 962 | goto expire; |
1da177e4 | 963 | |
22e2c507 | 964 | /* |
6d048f53 JA |
965 | * The active queue has requests and isn't expired, allow it to |
966 | * dispatch. | |
22e2c507 | 967 | */ |
dd67d051 | 968 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 969 | goto keep_queue; |
6d048f53 JA |
970 | |
971 | /* | |
972 | * No requests pending. If the active queue still has requests in | |
973 | * flight or is idling for a new request, allow either of these | |
974 | * conditions to happen (or time out) before selecting a new queue. | |
975 | */ | |
cc197479 JA |
976 | if (timer_pending(&cfqd->idle_slice_timer) || |
977 | (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { | |
caaa5f9f JA |
978 | cfqq = NULL; |
979 | goto keep_queue; | |
22e2c507 JA |
980 | } |
981 | ||
3b18152c | 982 | expire: |
6084cdda | 983 | cfq_slice_expired(cfqd, 0); |
3b18152c JA |
984 | new_queue: |
985 | cfqq = cfq_set_active_queue(cfqd); | |
22e2c507 | 986 | keep_queue: |
3b18152c | 987 | return cfqq; |
22e2c507 JA |
988 | } |
989 | ||
498d3aa2 JA |
990 | /* |
991 | * Dispatch some requests from cfqq, moving them to the request queue | |
992 | * dispatch list. | |
993 | */ | |
22e2c507 JA |
994 | static int |
995 | __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
996 | int max_dispatch) | |
997 | { | |
998 | int dispatched = 0; | |
999 | ||
dd67d051 | 1000 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
22e2c507 JA |
1001 | |
1002 | do { | |
5e705374 | 1003 | struct request *rq; |
1da177e4 LT |
1004 | |
1005 | /* | |
22e2c507 | 1006 | * follow expired path, else get first next available |
1da177e4 | 1007 | */ |
5e705374 JA |
1008 | if ((rq = cfq_check_fifo(cfqq)) == NULL) |
1009 | rq = cfqq->next_rq; | |
22e2c507 JA |
1010 | |
1011 | /* | |
1012 | * finally, insert request into driver dispatch list | |
1013 | */ | |
5e705374 | 1014 | cfq_dispatch_insert(cfqd->queue, rq); |
1da177e4 | 1015 | |
22e2c507 | 1016 | dispatched++; |
1da177e4 | 1017 | |
22e2c507 | 1018 | if (!cfqd->active_cic) { |
5e705374 JA |
1019 | atomic_inc(&RQ_CIC(rq)->ioc->refcount); |
1020 | cfqd->active_cic = RQ_CIC(rq); | |
22e2c507 | 1021 | } |
1da177e4 | 1022 | |
dd67d051 | 1023 | if (RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 JA |
1024 | break; |
1025 | ||
1026 | } while (dispatched < max_dispatch); | |
1027 | ||
22e2c507 JA |
1028 | /* |
1029 | * expire an async queue immediately if it has used up its slice. idle | |
1030 | * queue always expire after 1 dispatch round. | |
1031 | */ | |
a9938006 | 1032 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
20e493a8 | 1033 | dispatched >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
a9938006 | 1034 | cfq_class_idle(cfqq))) { |
44f7c160 | 1035 | cfqq->slice_end = jiffies + 1; |
6084cdda | 1036 | cfq_slice_expired(cfqd, 0); |
44f7c160 | 1037 | } |
22e2c507 JA |
1038 | |
1039 | return dispatched; | |
1040 | } | |
1041 | ||
febffd61 | 1042 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1043 | { |
1044 | int dispatched = 0; | |
1045 | ||
1046 | while (cfqq->next_rq) { | |
1047 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1048 | dispatched++; | |
1049 | } | |
1050 | ||
1051 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1052 | return dispatched; | |
1053 | } | |
1054 | ||
498d3aa2 JA |
1055 | /* |
1056 | * Drain our current requests. Used for barriers and when switching | |
1057 | * io schedulers on-the-fly. | |
1058 | */ | |
d9e7620e | 1059 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1060 | { |
0871714e | 1061 | struct cfq_queue *cfqq; |
d9e7620e | 1062 | int dispatched = 0; |
1b5ed5e1 | 1063 | |
0871714e | 1064 | while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL) |
d9e7620e | 1065 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1b5ed5e1 | 1066 | |
6084cdda | 1067 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1068 | |
1069 | BUG_ON(cfqd->busy_queues); | |
1070 | ||
1071 | return dispatched; | |
1072 | } | |
1073 | ||
165125e1 | 1074 | static int cfq_dispatch_requests(struct request_queue *q, int force) |
22e2c507 JA |
1075 | { |
1076 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
6d048f53 | 1077 | struct cfq_queue *cfqq; |
caaa5f9f | 1078 | int dispatched; |
22e2c507 JA |
1079 | |
1080 | if (!cfqd->busy_queues) | |
1081 | return 0; | |
1082 | ||
1b5ed5e1 TH |
1083 | if (unlikely(force)) |
1084 | return cfq_forced_dispatch(cfqd); | |
1085 | ||
caaa5f9f | 1086 | dispatched = 0; |
caaa5f9f | 1087 | while ((cfqq = cfq_select_queue(cfqd)) != NULL) { |
b4878f24 JA |
1088 | int max_dispatch; |
1089 | ||
3ed9a296 JA |
1090 | max_dispatch = cfqd->cfq_quantum; |
1091 | if (cfq_class_idle(cfqq)) | |
1092 | max_dispatch = 1; | |
1093 | ||
1094 | if (cfqq->dispatched >= max_dispatch) { | |
1095 | if (cfqd->busy_queues > 1) | |
6d048f53 | 1096 | break; |
3ed9a296 | 1097 | if (cfqq->dispatched >= 4 * max_dispatch) |
a9938006 JA |
1098 | break; |
1099 | } | |
9ede209e | 1100 | |
3ed9a296 JA |
1101 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) |
1102 | break; | |
1103 | ||
3b18152c JA |
1104 | cfq_clear_cfqq_must_dispatch(cfqq); |
1105 | cfq_clear_cfqq_wait_request(cfqq); | |
22e2c507 JA |
1106 | del_timer(&cfqd->idle_slice_timer); |
1107 | ||
caaa5f9f | 1108 | dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); |
1da177e4 LT |
1109 | } |
1110 | ||
caaa5f9f | 1111 | return dispatched; |
1da177e4 LT |
1112 | } |
1113 | ||
1da177e4 | 1114 | /* |
5e705374 JA |
1115 | * task holds one reference to the queue, dropped when task exits. each rq |
1116 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1117 | * |
1118 | * queue lock must be held here. | |
1119 | */ | |
1120 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1121 | { | |
22e2c507 JA |
1122 | struct cfq_data *cfqd = cfqq->cfqd; |
1123 | ||
1124 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1125 | |
1126 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1127 | return; | |
1128 | ||
1129 | BUG_ON(rb_first(&cfqq->sort_list)); | |
22e2c507 | 1130 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1131 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1132 | |
28f95cbc | 1133 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1134 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1135 | cfq_schedule_dispatch(cfqd); |
1136 | } | |
22e2c507 | 1137 | |
1da177e4 LT |
1138 | kmem_cache_free(cfq_pool, cfqq); |
1139 | } | |
1140 | ||
4ac845a2 JA |
1141 | /* |
1142 | * Call func for each cic attached to this ioc. Returns number of cic's seen. | |
1143 | */ | |
1144 | #define CIC_GANG_NR 16 | |
1145 | static unsigned int | |
1146 | call_for_each_cic(struct io_context *ioc, | |
1147 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1148 | { |
4ac845a2 JA |
1149 | struct cfq_io_context *cics[CIC_GANG_NR]; |
1150 | unsigned long index = 0; | |
1151 | unsigned int called = 0; | |
1152 | int nr; | |
1da177e4 | 1153 | |
4ac845a2 | 1154 | rcu_read_lock(); |
597bc485 | 1155 | |
4ac845a2 JA |
1156 | do { |
1157 | int i; | |
66dac98e | 1158 | |
4ac845a2 JA |
1159 | /* |
1160 | * Perhaps there's a better way - this just gang lookups from | |
1161 | * 0 to the end, restarting after each CIC_GANG_NR from the | |
1162 | * last key + 1. | |
1163 | */ | |
1164 | nr = radix_tree_gang_lookup(&ioc->radix_root, (void **) cics, | |
1165 | index, CIC_GANG_NR); | |
1166 | if (!nr) | |
1167 | break; | |
1168 | ||
1169 | called += nr; | |
1170 | index = 1 + (unsigned long) cics[nr - 1]->key; | |
1171 | ||
1172 | for (i = 0; i < nr; i++) | |
1173 | func(ioc, cics[i]); | |
1174 | } while (nr == CIC_GANG_NR); | |
1175 | ||
1176 | rcu_read_unlock(); | |
1177 | ||
1178 | return called; | |
1179 | } | |
1180 | ||
1181 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1182 | { | |
1183 | unsigned long flags; | |
1184 | ||
1185 | BUG_ON(!cic->dead_key); | |
1186 | ||
1187 | spin_lock_irqsave(&ioc->lock, flags); | |
1188 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
1189 | spin_unlock_irqrestore(&ioc->lock, flags); | |
1190 | ||
1191 | kmem_cache_free(cfq_ioc_pool, cic); | |
1192 | } | |
1193 | ||
1194 | static void cfq_free_io_context(struct io_context *ioc) | |
1195 | { | |
1196 | int freed; | |
1197 | ||
1198 | /* | |
1199 | * ioc->refcount is zero here, so no more cic's are allowed to be | |
1200 | * linked into this ioc. So it should be ok to iterate over the known | |
1201 | * list, we will see all cic's since no new ones are added. | |
1202 | */ | |
1203 | freed = call_for_each_cic(ioc, cic_free_func); | |
1da177e4 | 1204 | |
4050cf16 JA |
1205 | elv_ioc_count_mod(ioc_count, -freed); |
1206 | ||
1207 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) | |
334e94de | 1208 | complete(ioc_gone); |
1da177e4 LT |
1209 | } |
1210 | ||
89850f7e | 1211 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1212 | { |
28f95cbc | 1213 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1214 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1215 | cfq_schedule_dispatch(cfqd); |
1216 | } | |
22e2c507 | 1217 | |
89850f7e JA |
1218 | cfq_put_queue(cfqq); |
1219 | } | |
22e2c507 | 1220 | |
89850f7e JA |
1221 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1222 | struct cfq_io_context *cic) | |
1223 | { | |
fc46379d | 1224 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1225 | |
1226 | /* | |
1227 | * Make sure key == NULL is seen for dead queues | |
1228 | */ | |
fc46379d | 1229 | smp_wmb(); |
4ac845a2 | 1230 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1231 | cic->key = NULL; |
1232 | ||
12a05732 | 1233 | if (cic->cfqq[ASYNC]) { |
89850f7e | 1234 | cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]); |
12a05732 AV |
1235 | cic->cfqq[ASYNC] = NULL; |
1236 | } | |
1237 | ||
1238 | if (cic->cfqq[SYNC]) { | |
89850f7e | 1239 | cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]); |
12a05732 AV |
1240 | cic->cfqq[SYNC] = NULL; |
1241 | } | |
89850f7e JA |
1242 | } |
1243 | ||
4ac845a2 JA |
1244 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1245 | struct cfq_io_context *cic) | |
89850f7e JA |
1246 | { |
1247 | struct cfq_data *cfqd = cic->key; | |
1248 | ||
89850f7e | 1249 | if (cfqd) { |
165125e1 | 1250 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1251 | unsigned long flags; |
89850f7e | 1252 | |
4ac845a2 | 1253 | spin_lock_irqsave(q->queue_lock, flags); |
89850f7e | 1254 | __cfq_exit_single_io_context(cfqd, cic); |
4ac845a2 | 1255 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1256 | } |
1da177e4 LT |
1257 | } |
1258 | ||
498d3aa2 JA |
1259 | /* |
1260 | * The process that ioc belongs to has exited, we need to clean up | |
1261 | * and put the internal structures we have that belongs to that process. | |
1262 | */ | |
e2d74ac0 | 1263 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1264 | { |
4ac845a2 JA |
1265 | rcu_assign_pointer(ioc->ioc_data, NULL); |
1266 | call_for_each_cic(ioc, cfq_exit_single_io_context); | |
1da177e4 LT |
1267 | } |
1268 | ||
22e2c507 | 1269 | static struct cfq_io_context * |
8267e268 | 1270 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1271 | { |
b5deef90 | 1272 | struct cfq_io_context *cic; |
1da177e4 | 1273 | |
94f6030c CL |
1274 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1275 | cfqd->queue->node); | |
1da177e4 | 1276 | if (cic) { |
22e2c507 | 1277 | cic->last_end_request = jiffies; |
553698f9 | 1278 | INIT_LIST_HEAD(&cic->queue_list); |
22e2c507 JA |
1279 | cic->dtor = cfq_free_io_context; |
1280 | cic->exit = cfq_exit_io_context; | |
4050cf16 | 1281 | elv_ioc_count_inc(ioc_count); |
1da177e4 LT |
1282 | } |
1283 | ||
1284 | return cic; | |
1285 | } | |
1286 | ||
fd0928df | 1287 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1288 | { |
1289 | struct task_struct *tsk = current; | |
1290 | int ioprio_class; | |
1291 | ||
3b18152c | 1292 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1293 | return; |
1294 | ||
fd0928df | 1295 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 JA |
1296 | switch (ioprio_class) { |
1297 | default: | |
1298 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1299 | case IOPRIO_CLASS_NONE: | |
1300 | /* | |
1301 | * no prio set, place us in the middle of the BE classes | |
1302 | */ | |
1303 | cfqq->ioprio = task_nice_ioprio(tsk); | |
1304 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1305 | break; | |
1306 | case IOPRIO_CLASS_RT: | |
fd0928df | 1307 | cfqq->ioprio = task_ioprio(ioc); |
22e2c507 JA |
1308 | cfqq->ioprio_class = IOPRIO_CLASS_RT; |
1309 | break; | |
1310 | case IOPRIO_CLASS_BE: | |
fd0928df | 1311 | cfqq->ioprio = task_ioprio(ioc); |
22e2c507 JA |
1312 | cfqq->ioprio_class = IOPRIO_CLASS_BE; |
1313 | break; | |
1314 | case IOPRIO_CLASS_IDLE: | |
1315 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1316 | cfqq->ioprio = 7; | |
3b18152c | 1317 | cfq_clear_cfqq_idle_window(cfqq); |
22e2c507 JA |
1318 | break; |
1319 | } | |
1320 | ||
1321 | /* | |
1322 | * keep track of original prio settings in case we have to temporarily | |
1323 | * elevate the priority of this queue | |
1324 | */ | |
1325 | cfqq->org_ioprio = cfqq->ioprio; | |
1326 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1327 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1328 | } |
1329 | ||
febffd61 | 1330 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 1331 | { |
478a82b0 AV |
1332 | struct cfq_data *cfqd = cic->key; |
1333 | struct cfq_queue *cfqq; | |
c1b707d2 | 1334 | unsigned long flags; |
35e6077c | 1335 | |
caaa5f9f JA |
1336 | if (unlikely(!cfqd)) |
1337 | return; | |
1338 | ||
c1b707d2 | 1339 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f JA |
1340 | |
1341 | cfqq = cic->cfqq[ASYNC]; | |
1342 | if (cfqq) { | |
1343 | struct cfq_queue *new_cfqq; | |
fd0928df | 1344 | new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc, GFP_ATOMIC); |
caaa5f9f JA |
1345 | if (new_cfqq) { |
1346 | cic->cfqq[ASYNC] = new_cfqq; | |
1347 | cfq_put_queue(cfqq); | |
1348 | } | |
22e2c507 | 1349 | } |
caaa5f9f JA |
1350 | |
1351 | cfqq = cic->cfqq[SYNC]; | |
1352 | if (cfqq) | |
1353 | cfq_mark_cfqq_prio_changed(cfqq); | |
1354 | ||
c1b707d2 | 1355 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
1356 | } |
1357 | ||
fc46379d | 1358 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 1359 | { |
4ac845a2 | 1360 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 1361 | ioc->ioprio_changed = 0; |
22e2c507 JA |
1362 | } |
1363 | ||
1364 | static struct cfq_queue * | |
15c31be4 | 1365 | cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync, |
fd0928df | 1366 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 1367 | { |
22e2c507 | 1368 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 1369 | struct cfq_io_context *cic; |
22e2c507 JA |
1370 | |
1371 | retry: | |
4ac845a2 | 1372 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
1373 | /* cic always exists here */ |
1374 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 JA |
1375 | |
1376 | if (!cfqq) { | |
1377 | if (new_cfqq) { | |
1378 | cfqq = new_cfqq; | |
1379 | new_cfqq = NULL; | |
1380 | } else if (gfp_mask & __GFP_WAIT) { | |
89850f7e JA |
1381 | /* |
1382 | * Inform the allocator of the fact that we will | |
1383 | * just repeat this allocation if it fails, to allow | |
1384 | * the allocator to do whatever it needs to attempt to | |
1385 | * free memory. | |
1386 | */ | |
22e2c507 | 1387 | spin_unlock_irq(cfqd->queue->queue_lock); |
94f6030c CL |
1388 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
1389 | gfp_mask | __GFP_NOFAIL | __GFP_ZERO, | |
1390 | cfqd->queue->node); | |
22e2c507 JA |
1391 | spin_lock_irq(cfqd->queue->queue_lock); |
1392 | goto retry; | |
1393 | } else { | |
94f6030c CL |
1394 | cfqq = kmem_cache_alloc_node(cfq_pool, |
1395 | gfp_mask | __GFP_ZERO, | |
1396 | cfqd->queue->node); | |
22e2c507 JA |
1397 | if (!cfqq) |
1398 | goto out; | |
1399 | } | |
1400 | ||
d9e7620e | 1401 | RB_CLEAR_NODE(&cfqq->rb_node); |
22e2c507 JA |
1402 | INIT_LIST_HEAD(&cfqq->fifo); |
1403 | ||
22e2c507 JA |
1404 | atomic_set(&cfqq->ref, 0); |
1405 | cfqq->cfqd = cfqd; | |
c5b680f3 | 1406 | |
3b18152c | 1407 | cfq_mark_cfqq_prio_changed(cfqq); |
53b03744 | 1408 | cfq_mark_cfqq_queue_new(cfqq); |
91fac317 | 1409 | |
fd0928df | 1410 | cfq_init_prio_data(cfqq, ioc); |
0871714e JA |
1411 | |
1412 | if (is_sync) { | |
1413 | if (!cfq_class_idle(cfqq)) | |
1414 | cfq_mark_cfqq_idle_window(cfqq); | |
1415 | cfq_mark_cfqq_sync(cfqq); | |
1416 | } | |
22e2c507 JA |
1417 | } |
1418 | ||
1419 | if (new_cfqq) | |
1420 | kmem_cache_free(cfq_pool, new_cfqq); | |
1421 | ||
22e2c507 JA |
1422 | out: |
1423 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1424 | return cfqq; | |
1425 | } | |
1426 | ||
c2dea2d1 VT |
1427 | static struct cfq_queue ** |
1428 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
1429 | { | |
1430 | switch(ioprio_class) { | |
1431 | case IOPRIO_CLASS_RT: | |
1432 | return &cfqd->async_cfqq[0][ioprio]; | |
1433 | case IOPRIO_CLASS_BE: | |
1434 | return &cfqd->async_cfqq[1][ioprio]; | |
1435 | case IOPRIO_CLASS_IDLE: | |
1436 | return &cfqd->async_idle_cfqq; | |
1437 | default: | |
1438 | BUG(); | |
1439 | } | |
1440 | } | |
1441 | ||
15c31be4 | 1442 | static struct cfq_queue * |
fd0928df | 1443 | cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc, |
15c31be4 JA |
1444 | gfp_t gfp_mask) |
1445 | { | |
fd0928df JA |
1446 | const int ioprio = task_ioprio(ioc); |
1447 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 1448 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
1449 | struct cfq_queue *cfqq = NULL; |
1450 | ||
c2dea2d1 VT |
1451 | if (!is_sync) { |
1452 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
1453 | cfqq = *async_cfqq; | |
1454 | } | |
1455 | ||
0a0836a0 | 1456 | if (!cfqq) { |
fd0928df | 1457 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
0a0836a0 ON |
1458 | if (!cfqq) |
1459 | return NULL; | |
1460 | } | |
15c31be4 JA |
1461 | |
1462 | /* | |
1463 | * pin the queue now that it's allocated, scheduler exit will prune it | |
1464 | */ | |
c2dea2d1 | 1465 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 1466 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 1467 | *async_cfqq = cfqq; |
15c31be4 JA |
1468 | } |
1469 | ||
1470 | atomic_inc(&cfqq->ref); | |
1471 | return cfqq; | |
1472 | } | |
1473 | ||
4ac845a2 JA |
1474 | static void cfq_cic_free(struct cfq_io_context *cic) |
1475 | { | |
1476 | kmem_cache_free(cfq_ioc_pool, cic); | |
1477 | elv_ioc_count_dec(ioc_count); | |
1478 | ||
1479 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) | |
1480 | complete(ioc_gone); | |
1481 | } | |
1482 | ||
498d3aa2 JA |
1483 | /* |
1484 | * We drop cfq io contexts lazily, so we may find a dead one. | |
1485 | */ | |
dbecf3ab | 1486 | static void |
4ac845a2 JA |
1487 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
1488 | struct cfq_io_context *cic) | |
dbecf3ab | 1489 | { |
4ac845a2 JA |
1490 | unsigned long flags; |
1491 | ||
fc46379d | 1492 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 1493 | |
4ac845a2 JA |
1494 | spin_lock_irqsave(&ioc->lock, flags); |
1495 | ||
597bc485 | 1496 | if (ioc->ioc_data == cic) |
4ac845a2 | 1497 | rcu_assign_pointer(ioc->ioc_data, NULL); |
597bc485 | 1498 | |
4ac845a2 JA |
1499 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
1500 | spin_unlock_irqrestore(&ioc->lock, flags); | |
1501 | ||
1502 | cfq_cic_free(cic); | |
dbecf3ab OH |
1503 | } |
1504 | ||
e2d74ac0 | 1505 | static struct cfq_io_context * |
4ac845a2 | 1506 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 1507 | { |
e2d74ac0 | 1508 | struct cfq_io_context *cic; |
4ac845a2 | 1509 | void *k; |
e2d74ac0 | 1510 | |
91fac317 VT |
1511 | if (unlikely(!ioc)) |
1512 | return NULL; | |
1513 | ||
597bc485 JA |
1514 | /* |
1515 | * we maintain a last-hit cache, to avoid browsing over the tree | |
1516 | */ | |
4ac845a2 | 1517 | cic = rcu_dereference(ioc->ioc_data); |
597bc485 JA |
1518 | if (cic && cic->key == cfqd) |
1519 | return cic; | |
1520 | ||
4ac845a2 JA |
1521 | do { |
1522 | rcu_read_lock(); | |
1523 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); | |
1524 | rcu_read_unlock(); | |
1525 | if (!cic) | |
1526 | break; | |
be3b0753 OH |
1527 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1528 | k = cic->key; | |
1529 | if (unlikely(!k)) { | |
4ac845a2 JA |
1530 | cfq_drop_dead_cic(cfqd, ioc, cic); |
1531 | continue; | |
dbecf3ab | 1532 | } |
e2d74ac0 | 1533 | |
4ac845a2 JA |
1534 | rcu_assign_pointer(ioc->ioc_data, cic); |
1535 | break; | |
1536 | } while (1); | |
e2d74ac0 | 1537 | |
4ac845a2 | 1538 | return cic; |
e2d74ac0 JA |
1539 | } |
1540 | ||
4ac845a2 JA |
1541 | /* |
1542 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
1543 | * the process specific cfq io context when entered from the block layer. | |
1544 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
1545 | */ | |
febffd61 JA |
1546 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
1547 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 1548 | { |
0261d688 | 1549 | unsigned long flags; |
4ac845a2 | 1550 | int ret; |
e2d74ac0 | 1551 | |
4ac845a2 JA |
1552 | ret = radix_tree_preload(gfp_mask); |
1553 | if (!ret) { | |
1554 | cic->ioc = ioc; | |
1555 | cic->key = cfqd; | |
e2d74ac0 | 1556 | |
4ac845a2 JA |
1557 | spin_lock_irqsave(&ioc->lock, flags); |
1558 | ret = radix_tree_insert(&ioc->radix_root, | |
1559 | (unsigned long) cfqd, cic); | |
1560 | spin_unlock_irqrestore(&ioc->lock, flags); | |
e2d74ac0 | 1561 | |
4ac845a2 JA |
1562 | radix_tree_preload_end(); |
1563 | ||
1564 | if (!ret) { | |
1565 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1566 | list_add(&cic->queue_list, &cfqd->cic_list); | |
1567 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1568 | } | |
e2d74ac0 JA |
1569 | } |
1570 | ||
4ac845a2 JA |
1571 | if (ret) |
1572 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 1573 | |
4ac845a2 | 1574 | return ret; |
e2d74ac0 JA |
1575 | } |
1576 | ||
1da177e4 LT |
1577 | /* |
1578 | * Setup general io context and cfq io context. There can be several cfq | |
1579 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1580 | * than one device managed by cfq. |
1da177e4 LT |
1581 | */ |
1582 | static struct cfq_io_context * | |
e2d74ac0 | 1583 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1584 | { |
22e2c507 | 1585 | struct io_context *ioc = NULL; |
1da177e4 | 1586 | struct cfq_io_context *cic; |
1da177e4 | 1587 | |
22e2c507 | 1588 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1589 | |
b5deef90 | 1590 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
1591 | if (!ioc) |
1592 | return NULL; | |
1593 | ||
4ac845a2 | 1594 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
1595 | if (cic) |
1596 | goto out; | |
1da177e4 | 1597 | |
e2d74ac0 JA |
1598 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1599 | if (cic == NULL) | |
1600 | goto err; | |
1da177e4 | 1601 | |
4ac845a2 JA |
1602 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
1603 | goto err_free; | |
1604 | ||
1da177e4 | 1605 | out: |
fc46379d JA |
1606 | smp_read_barrier_depends(); |
1607 | if (unlikely(ioc->ioprio_changed)) | |
1608 | cfq_ioc_set_ioprio(ioc); | |
1609 | ||
1da177e4 | 1610 | return cic; |
4ac845a2 JA |
1611 | err_free: |
1612 | cfq_cic_free(cic); | |
1da177e4 LT |
1613 | err: |
1614 | put_io_context(ioc); | |
1615 | return NULL; | |
1616 | } | |
1617 | ||
22e2c507 JA |
1618 | static void |
1619 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1620 | { |
aaf1228d JA |
1621 | unsigned long elapsed = jiffies - cic->last_end_request; |
1622 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 1623 | |
22e2c507 JA |
1624 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1625 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1626 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1627 | } | |
1da177e4 | 1628 | |
206dc69b | 1629 | static void |
6d048f53 JA |
1630 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, |
1631 | struct request *rq) | |
206dc69b JA |
1632 | { |
1633 | sector_t sdist; | |
1634 | u64 total; | |
1635 | ||
5e705374 JA |
1636 | if (cic->last_request_pos < rq->sector) |
1637 | sdist = rq->sector - cic->last_request_pos; | |
206dc69b | 1638 | else |
5e705374 | 1639 | sdist = cic->last_request_pos - rq->sector; |
206dc69b JA |
1640 | |
1641 | /* | |
1642 | * Don't allow the seek distance to get too large from the | |
1643 | * odd fragment, pagein, etc | |
1644 | */ | |
1645 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1646 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1647 | else | |
1648 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1649 | ||
1650 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1651 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1652 | total = cic->seek_total + (cic->seek_samples/2); | |
1653 | do_div(total, cic->seek_samples); | |
1654 | cic->seek_mean = (sector_t)total; | |
1655 | } | |
1da177e4 | 1656 | |
22e2c507 JA |
1657 | /* |
1658 | * Disable idle window if the process thinks too long or seeks so much that | |
1659 | * it doesn't matter | |
1660 | */ | |
1661 | static void | |
1662 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1663 | struct cfq_io_context *cic) | |
1664 | { | |
1be92f2f JA |
1665 | int enable_idle; |
1666 | ||
0871714e JA |
1667 | /* |
1668 | * Don't idle for async or idle io prio class | |
1669 | */ | |
1670 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
1671 | return; |
1672 | ||
1673 | enable_idle = cfq_cfqq_idle_window(cfqq); | |
1da177e4 | 1674 | |
66dac98e | 1675 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
caaa5f9f | 1676 | (cfqd->hw_tag && CIC_SEEKY(cic))) |
22e2c507 JA |
1677 | enable_idle = 0; |
1678 | else if (sample_valid(cic->ttime_samples)) { | |
1679 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1680 | enable_idle = 0; | |
1681 | else | |
1682 | enable_idle = 1; | |
1da177e4 LT |
1683 | } |
1684 | ||
3b18152c JA |
1685 | if (enable_idle) |
1686 | cfq_mark_cfqq_idle_window(cfqq); | |
1687 | else | |
1688 | cfq_clear_cfqq_idle_window(cfqq); | |
22e2c507 | 1689 | } |
1da177e4 | 1690 | |
22e2c507 JA |
1691 | /* |
1692 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1693 | * no or if we aren't sure, a 1 will cause a preempt. | |
1694 | */ | |
1695 | static int | |
1696 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
5e705374 | 1697 | struct request *rq) |
22e2c507 | 1698 | { |
6d048f53 | 1699 | struct cfq_queue *cfqq; |
22e2c507 | 1700 | |
6d048f53 JA |
1701 | cfqq = cfqd->active_queue; |
1702 | if (!cfqq) | |
22e2c507 JA |
1703 | return 0; |
1704 | ||
6d048f53 JA |
1705 | if (cfq_slice_used(cfqq)) |
1706 | return 1; | |
1707 | ||
1708 | if (cfq_class_idle(new_cfqq)) | |
caaa5f9f | 1709 | return 0; |
22e2c507 JA |
1710 | |
1711 | if (cfq_class_idle(cfqq)) | |
1712 | return 1; | |
1e3335de | 1713 | |
374f84ac JA |
1714 | /* |
1715 | * if the new request is sync, but the currently running queue is | |
1716 | * not, let the sync request have priority. | |
1717 | */ | |
5e705374 | 1718 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 | 1719 | return 1; |
1e3335de | 1720 | |
374f84ac JA |
1721 | /* |
1722 | * So both queues are sync. Let the new request get disk time if | |
1723 | * it's a metadata request and the current queue is doing regular IO. | |
1724 | */ | |
1725 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
1726 | return 1; | |
22e2c507 | 1727 | |
1e3335de JA |
1728 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
1729 | return 0; | |
1730 | ||
1731 | /* | |
1732 | * if this request is as-good as one we would expect from the | |
1733 | * current cfqq, let it preempt | |
1734 | */ | |
6d048f53 | 1735 | if (cfq_rq_close(cfqd, rq)) |
1e3335de JA |
1736 | return 1; |
1737 | ||
22e2c507 JA |
1738 | return 0; |
1739 | } | |
1740 | ||
1741 | /* | |
1742 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
1743 | * let it have half of its nominal slice. | |
1744 | */ | |
1745 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1746 | { | |
6084cdda | 1747 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 1748 | |
bf572256 JA |
1749 | /* |
1750 | * Put the new queue at the front of the of the current list, | |
1751 | * so we know that it will be selected next. | |
1752 | */ | |
1753 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
1754 | |
1755 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 1756 | |
44f7c160 JA |
1757 | cfqq->slice_end = 0; |
1758 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
1759 | } |
1760 | ||
22e2c507 | 1761 | /* |
5e705374 | 1762 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
1763 | * something we should do about it |
1764 | */ | |
1765 | static void | |
5e705374 JA |
1766 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1767 | struct request *rq) | |
22e2c507 | 1768 | { |
5e705374 | 1769 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 1770 | |
374f84ac JA |
1771 | if (rq_is_meta(rq)) |
1772 | cfqq->meta_pending++; | |
1773 | ||
9c2c38a1 | 1774 | cfq_update_io_thinktime(cfqd, cic); |
6d048f53 | 1775 | cfq_update_io_seektime(cfqd, cic, rq); |
9c2c38a1 JA |
1776 | cfq_update_idle_window(cfqd, cfqq, cic); |
1777 | ||
5e705374 | 1778 | cic->last_request_pos = rq->sector + rq->nr_sectors; |
22e2c507 JA |
1779 | |
1780 | if (cfqq == cfqd->active_queue) { | |
1781 | /* | |
1782 | * if we are waiting for a request for this queue, let it rip | |
1783 | * immediately and flag that we must not expire this queue | |
1784 | * just now | |
1785 | */ | |
3b18152c JA |
1786 | if (cfq_cfqq_wait_request(cfqq)) { |
1787 | cfq_mark_cfqq_must_dispatch(cfqq); | |
22e2c507 | 1788 | del_timer(&cfqd->idle_slice_timer); |
dc72ef4a | 1789 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1790 | } |
5e705374 | 1791 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
1792 | /* |
1793 | * not the active queue - expire current slice if it is | |
1794 | * idle and has expired it's mean thinktime or this new queue | |
1795 | * has some old slice time left and is of higher priority | |
1796 | */ | |
1797 | cfq_preempt_queue(cfqd, cfqq); | |
3b18152c | 1798 | cfq_mark_cfqq_must_dispatch(cfqq); |
dc72ef4a | 1799 | blk_start_queueing(cfqd->queue); |
22e2c507 | 1800 | } |
1da177e4 LT |
1801 | } |
1802 | ||
165125e1 | 1803 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 1804 | { |
b4878f24 | 1805 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1806 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1807 | |
fd0928df | 1808 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 1809 | |
5e705374 | 1810 | cfq_add_rq_rb(rq); |
1da177e4 | 1811 | |
22e2c507 JA |
1812 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
1813 | ||
5e705374 | 1814 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
1815 | } |
1816 | ||
165125e1 | 1817 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 1818 | { |
5e705374 | 1819 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 1820 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 1821 | const int sync = rq_is_sync(rq); |
b4878f24 | 1822 | unsigned long now; |
1da177e4 | 1823 | |
b4878f24 | 1824 | now = jiffies; |
1da177e4 | 1825 | |
b4878f24 | 1826 | WARN_ON(!cfqd->rq_in_driver); |
6d048f53 | 1827 | WARN_ON(!cfqq->dispatched); |
b4878f24 | 1828 | cfqd->rq_in_driver--; |
6d048f53 | 1829 | cfqq->dispatched--; |
1da177e4 | 1830 | |
3ed9a296 JA |
1831 | if (cfq_cfqq_sync(cfqq)) |
1832 | cfqd->sync_flight--; | |
1833 | ||
b4878f24 JA |
1834 | if (!cfq_class_idle(cfqq)) |
1835 | cfqd->last_end_request = now; | |
3b18152c | 1836 | |
caaa5f9f | 1837 | if (sync) |
5e705374 | 1838 | RQ_CIC(rq)->last_end_request = now; |
caaa5f9f JA |
1839 | |
1840 | /* | |
1841 | * If this is the active queue, check if it needs to be expired, | |
1842 | * or if we want to idle in case it has no pending requests. | |
1843 | */ | |
1844 | if (cfqd->active_queue == cfqq) { | |
44f7c160 JA |
1845 | if (cfq_cfqq_slice_new(cfqq)) { |
1846 | cfq_set_prio_slice(cfqd, cfqq); | |
1847 | cfq_clear_cfqq_slice_new(cfqq); | |
1848 | } | |
0871714e | 1849 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 1850 | cfq_slice_expired(cfqd, 1); |
6d048f53 JA |
1851 | else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) |
1852 | cfq_arm_slice_timer(cfqd); | |
caaa5f9f | 1853 | } |
6d048f53 JA |
1854 | |
1855 | if (!cfqd->rq_in_driver) | |
1856 | cfq_schedule_dispatch(cfqd); | |
1da177e4 LT |
1857 | } |
1858 | ||
22e2c507 JA |
1859 | /* |
1860 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
1861 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
1862 | */ | |
1863 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 1864 | { |
22e2c507 JA |
1865 | if (has_fs_excl()) { |
1866 | /* | |
1867 | * boost idle prio on transactions that would lock out other | |
1868 | * users of the filesystem | |
1869 | */ | |
1870 | if (cfq_class_idle(cfqq)) | |
1871 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1872 | if (cfqq->ioprio > IOPRIO_NORM) | |
1873 | cfqq->ioprio = IOPRIO_NORM; | |
1874 | } else { | |
1875 | /* | |
1876 | * check if we need to unboost the queue | |
1877 | */ | |
1878 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
1879 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
1880 | if (cfqq->ioprio != cfqq->org_ioprio) | |
1881 | cfqq->ioprio = cfqq->org_ioprio; | |
1882 | } | |
22e2c507 | 1883 | } |
1da177e4 | 1884 | |
89850f7e | 1885 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 1886 | { |
3b18152c | 1887 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && |
99f95e52 | 1888 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 1889 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 1890 | return ELV_MQUEUE_MUST; |
3b18152c | 1891 | } |
1da177e4 | 1892 | |
22e2c507 | 1893 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
1894 | } |
1895 | ||
165125e1 | 1896 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
1897 | { |
1898 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1899 | struct task_struct *tsk = current; | |
91fac317 | 1900 | struct cfq_io_context *cic; |
22e2c507 JA |
1901 | struct cfq_queue *cfqq; |
1902 | ||
1903 | /* | |
1904 | * don't force setup of a queue from here, as a call to may_queue | |
1905 | * does not necessarily imply that a request actually will be queued. | |
1906 | * so just lookup a possibly existing queue, or return 'may queue' | |
1907 | * if that fails | |
1908 | */ | |
4ac845a2 | 1909 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
1910 | if (!cic) |
1911 | return ELV_MQUEUE_MAY; | |
1912 | ||
1913 | cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC); | |
22e2c507 | 1914 | if (cfqq) { |
fd0928df | 1915 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
1916 | cfq_prio_boost(cfqq); |
1917 | ||
89850f7e | 1918 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
1919 | } |
1920 | ||
1921 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
1922 | } |
1923 | ||
1da177e4 LT |
1924 | /* |
1925 | * queue lock held here | |
1926 | */ | |
bb37b94c | 1927 | static void cfq_put_request(struct request *rq) |
1da177e4 | 1928 | { |
5e705374 | 1929 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 1930 | |
5e705374 | 1931 | if (cfqq) { |
22e2c507 | 1932 | const int rw = rq_data_dir(rq); |
1da177e4 | 1933 | |
22e2c507 JA |
1934 | BUG_ON(!cfqq->allocated[rw]); |
1935 | cfqq->allocated[rw]--; | |
1da177e4 | 1936 | |
5e705374 | 1937 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 1938 | |
1da177e4 | 1939 | rq->elevator_private = NULL; |
5e705374 | 1940 | rq->elevator_private2 = NULL; |
1da177e4 | 1941 | |
1da177e4 LT |
1942 | cfq_put_queue(cfqq); |
1943 | } | |
1944 | } | |
1945 | ||
1946 | /* | |
22e2c507 | 1947 | * Allocate cfq data structures associated with this request. |
1da177e4 | 1948 | */ |
22e2c507 | 1949 | static int |
165125e1 | 1950 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
1951 | { |
1952 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1953 | struct cfq_io_context *cic; | |
1954 | const int rw = rq_data_dir(rq); | |
7749a8d4 | 1955 | const int is_sync = rq_is_sync(rq); |
22e2c507 | 1956 | struct cfq_queue *cfqq; |
1da177e4 LT |
1957 | unsigned long flags; |
1958 | ||
1959 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
1960 | ||
e2d74ac0 | 1961 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 1962 | |
1da177e4 LT |
1963 | spin_lock_irqsave(q->queue_lock, flags); |
1964 | ||
22e2c507 JA |
1965 | if (!cic) |
1966 | goto queue_fail; | |
1967 | ||
91fac317 VT |
1968 | cfqq = cic_to_cfqq(cic, is_sync); |
1969 | if (!cfqq) { | |
fd0928df | 1970 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 1971 | |
22e2c507 JA |
1972 | if (!cfqq) |
1973 | goto queue_fail; | |
1da177e4 | 1974 | |
91fac317 VT |
1975 | cic_set_cfqq(cic, cfqq, is_sync); |
1976 | } | |
1da177e4 LT |
1977 | |
1978 | cfqq->allocated[rw]++; | |
3b18152c | 1979 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 | 1980 | atomic_inc(&cfqq->ref); |
1da177e4 | 1981 | |
5e705374 | 1982 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 1983 | |
5e705374 JA |
1984 | rq->elevator_private = cic; |
1985 | rq->elevator_private2 = cfqq; | |
1986 | return 0; | |
1da177e4 | 1987 | |
22e2c507 JA |
1988 | queue_fail: |
1989 | if (cic) | |
1990 | put_io_context(cic->ioc); | |
89850f7e | 1991 | |
3b18152c | 1992 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
1993 | spin_unlock_irqrestore(q->queue_lock, flags); |
1994 | return 1; | |
1995 | } | |
1996 | ||
65f27f38 | 1997 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 1998 | { |
65f27f38 DH |
1999 | struct cfq_data *cfqd = |
2000 | container_of(work, struct cfq_data, unplug_work); | |
165125e1 | 2001 | struct request_queue *q = cfqd->queue; |
22e2c507 JA |
2002 | unsigned long flags; |
2003 | ||
2004 | spin_lock_irqsave(q->queue_lock, flags); | |
dc72ef4a | 2005 | blk_start_queueing(q); |
22e2c507 JA |
2006 | spin_unlock_irqrestore(q->queue_lock, flags); |
2007 | } | |
2008 | ||
2009 | /* | |
2010 | * Timer running if the active_queue is currently idling inside its time slice | |
2011 | */ | |
2012 | static void cfq_idle_slice_timer(unsigned long data) | |
2013 | { | |
2014 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2015 | struct cfq_queue *cfqq; | |
2016 | unsigned long flags; | |
3c6bd2f8 | 2017 | int timed_out = 1; |
22e2c507 JA |
2018 | |
2019 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2020 | ||
2021 | if ((cfqq = cfqd->active_queue) != NULL) { | |
3c6bd2f8 JA |
2022 | timed_out = 0; |
2023 | ||
22e2c507 JA |
2024 | /* |
2025 | * expired | |
2026 | */ | |
44f7c160 | 2027 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2028 | goto expire; |
2029 | ||
2030 | /* | |
2031 | * only expire and reinvoke request handler, if there are | |
2032 | * other queues with pending requests | |
2033 | */ | |
caaa5f9f | 2034 | if (!cfqd->busy_queues) |
22e2c507 | 2035 | goto out_cont; |
22e2c507 JA |
2036 | |
2037 | /* | |
2038 | * not expired and it has a request pending, let it dispatch | |
2039 | */ | |
dd67d051 | 2040 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) { |
3b18152c | 2041 | cfq_mark_cfqq_must_dispatch(cfqq); |
22e2c507 JA |
2042 | goto out_kick; |
2043 | } | |
2044 | } | |
2045 | expire: | |
6084cdda | 2046 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2047 | out_kick: |
3b18152c | 2048 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2049 | out_cont: |
2050 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2051 | } | |
2052 | ||
3b18152c JA |
2053 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2054 | { | |
2055 | del_timer_sync(&cfqd->idle_slice_timer); | |
4310864b | 2056 | kblockd_flush_work(&cfqd->unplug_work); |
3b18152c | 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]); | |
c2dea2d1 | 2068 | } |
2389d1ef ON |
2069 | |
2070 | if (cfqd->async_idle_cfqq) | |
2071 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2072 | } |
2073 | ||
1da177e4 LT |
2074 | static void cfq_exit_queue(elevator_t *e) |
2075 | { | |
22e2c507 | 2076 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2077 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2078 | |
3b18152c | 2079 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2080 | |
d9ff4187 | 2081 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2082 | |
d9ff4187 | 2083 | if (cfqd->active_queue) |
6084cdda | 2084 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2085 | |
2086 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2087 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2088 | struct cfq_io_context, | |
2089 | queue_list); | |
89850f7e JA |
2090 | |
2091 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2092 | } |
e2d74ac0 | 2093 | |
c2dea2d1 | 2094 | cfq_put_async_queues(cfqd); |
15c31be4 | 2095 | |
d9ff4187 | 2096 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2097 | |
2098 | cfq_shutdown_timer_wq(cfqd); | |
2099 | ||
a90d742e | 2100 | kfree(cfqd); |
1da177e4 LT |
2101 | } |
2102 | ||
165125e1 | 2103 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2104 | { |
2105 | struct cfq_data *cfqd; | |
1da177e4 | 2106 | |
94f6030c | 2107 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2108 | if (!cfqd) |
bc1c1169 | 2109 | return NULL; |
1da177e4 | 2110 | |
cc09e299 | 2111 | cfqd->service_tree = CFQ_RB_ROOT; |
d9ff4187 | 2112 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2113 | |
1da177e4 | 2114 | cfqd->queue = q; |
1da177e4 | 2115 | |
22e2c507 JA |
2116 | init_timer(&cfqd->idle_slice_timer); |
2117 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2118 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2119 | ||
65f27f38 | 2120 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2121 | |
b70c864d | 2122 | cfqd->last_end_request = jiffies; |
1da177e4 | 2123 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2124 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2125 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2126 | cfqd->cfq_back_max = cfq_back_max; |
2127 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2128 | cfqd->cfq_slice[0] = cfq_slice_async; |
2129 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2130 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2131 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3b18152c | 2132 | |
bc1c1169 | 2133 | return cfqd; |
1da177e4 LT |
2134 | } |
2135 | ||
2136 | static void cfq_slab_kill(void) | |
2137 | { | |
1da177e4 LT |
2138 | if (cfq_pool) |
2139 | kmem_cache_destroy(cfq_pool); | |
2140 | if (cfq_ioc_pool) | |
2141 | kmem_cache_destroy(cfq_ioc_pool); | |
2142 | } | |
2143 | ||
2144 | static int __init cfq_slab_setup(void) | |
2145 | { | |
0a31bd5f | 2146 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
2147 | if (!cfq_pool) |
2148 | goto fail; | |
2149 | ||
4ac845a2 | 2150 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, SLAB_DESTROY_BY_RCU); |
1da177e4 LT |
2151 | if (!cfq_ioc_pool) |
2152 | goto fail; | |
2153 | ||
2154 | return 0; | |
2155 | fail: | |
2156 | cfq_slab_kill(); | |
2157 | return -ENOMEM; | |
2158 | } | |
2159 | ||
1da177e4 LT |
2160 | /* |
2161 | * sysfs parts below --> | |
2162 | */ | |
1da177e4 LT |
2163 | static ssize_t |
2164 | cfq_var_show(unsigned int var, char *page) | |
2165 | { | |
2166 | return sprintf(page, "%d\n", var); | |
2167 | } | |
2168 | ||
2169 | static ssize_t | |
2170 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2171 | { | |
2172 | char *p = (char *) page; | |
2173 | ||
2174 | *var = simple_strtoul(p, &p, 10); | |
2175 | return count; | |
2176 | } | |
2177 | ||
1da177e4 | 2178 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
3d1ab40f | 2179 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 2180 | { \ |
3d1ab40f | 2181 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2182 | unsigned int __data = __VAR; \ |
2183 | if (__CONV) \ | |
2184 | __data = jiffies_to_msecs(__data); \ | |
2185 | return cfq_var_show(__data, (page)); \ | |
2186 | } | |
2187 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
2188 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2189 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2190 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2191 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2192 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2193 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2194 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2195 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2196 | #undef SHOW_FUNCTION |
2197 | ||
2198 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 2199 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 2200 | { \ |
3d1ab40f | 2201 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2202 | unsigned int __data; \ |
2203 | int ret = cfq_var_store(&__data, (page), count); \ | |
2204 | if (__data < (MIN)) \ | |
2205 | __data = (MIN); \ | |
2206 | else if (__data > (MAX)) \ | |
2207 | __data = (MAX); \ | |
2208 | if (__CONV) \ | |
2209 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2210 | else \ | |
2211 | *(__PTR) = __data; \ | |
2212 | return ret; \ | |
2213 | } | |
2214 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
22e2c507 JA |
2215 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); |
2216 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); | |
e572ec7e AV |
2217 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
2218 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); | |
22e2c507 JA |
2219 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2220 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2221 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
2222 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); | |
1da177e4 LT |
2223 | #undef STORE_FUNCTION |
2224 | ||
e572ec7e AV |
2225 | #define CFQ_ATTR(name) \ |
2226 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2227 | ||
2228 | static struct elv_fs_entry cfq_attrs[] = { | |
2229 | CFQ_ATTR(quantum), | |
e572ec7e AV |
2230 | CFQ_ATTR(fifo_expire_sync), |
2231 | CFQ_ATTR(fifo_expire_async), | |
2232 | CFQ_ATTR(back_seek_max), | |
2233 | CFQ_ATTR(back_seek_penalty), | |
2234 | CFQ_ATTR(slice_sync), | |
2235 | CFQ_ATTR(slice_async), | |
2236 | CFQ_ATTR(slice_async_rq), | |
2237 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2238 | __ATTR_NULL |
1da177e4 LT |
2239 | }; |
2240 | ||
1da177e4 LT |
2241 | static struct elevator_type iosched_cfq = { |
2242 | .ops = { | |
2243 | .elevator_merge_fn = cfq_merge, | |
2244 | .elevator_merged_fn = cfq_merged_request, | |
2245 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 2246 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 2247 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2248 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2249 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2250 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2251 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2252 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
2253 | .elevator_former_req_fn = elv_rb_former_request, |
2254 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
2255 | .elevator_set_req_fn = cfq_set_request, |
2256 | .elevator_put_req_fn = cfq_put_request, | |
2257 | .elevator_may_queue_fn = cfq_may_queue, | |
2258 | .elevator_init_fn = cfq_init_queue, | |
2259 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 2260 | .trim = cfq_free_io_context, |
1da177e4 | 2261 | }, |
3d1ab40f | 2262 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2263 | .elevator_name = "cfq", |
2264 | .elevator_owner = THIS_MODULE, | |
2265 | }; | |
2266 | ||
2267 | static int __init cfq_init(void) | |
2268 | { | |
22e2c507 JA |
2269 | /* |
2270 | * could be 0 on HZ < 1000 setups | |
2271 | */ | |
2272 | if (!cfq_slice_async) | |
2273 | cfq_slice_async = 1; | |
2274 | if (!cfq_slice_idle) | |
2275 | cfq_slice_idle = 1; | |
2276 | ||
1da177e4 LT |
2277 | if (cfq_slab_setup()) |
2278 | return -ENOMEM; | |
2279 | ||
2fdd82bd | 2280 | elv_register(&iosched_cfq); |
1da177e4 | 2281 | |
2fdd82bd | 2282 | return 0; |
1da177e4 LT |
2283 | } |
2284 | ||
2285 | static void __exit cfq_exit(void) | |
2286 | { | |
6e9a4738 | 2287 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 2288 | elv_unregister(&iosched_cfq); |
334e94de | 2289 | ioc_gone = &all_gone; |
fba82272 OH |
2290 | /* ioc_gone's update must be visible before reading ioc_count */ |
2291 | smp_wmb(); | |
4050cf16 | 2292 | if (elv_ioc_count_read(ioc_count)) |
fba82272 | 2293 | wait_for_completion(ioc_gone); |
334e94de | 2294 | synchronize_rcu(); |
83521d3e | 2295 | cfq_slab_kill(); |
1da177e4 LT |
2296 | } |
2297 | ||
2298 | module_init(cfq_init); | |
2299 | module_exit(cfq_exit); | |
2300 | ||
2301 | MODULE_AUTHOR("Jens Axboe"); | |
2302 | MODULE_LICENSE("GPL"); | |
2303 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |