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> |
7b679138 | 14 | #include <linux/blktrace_api.h> |
1da177e4 LT |
15 | |
16 | /* | |
17 | * tunables | |
18 | */ | |
fe094d98 JA |
19 | /* max queue in one round of service */ |
20 | static const int cfq_quantum = 4; | |
64100099 | 21 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
fe094d98 JA |
22 | /* maximum backwards seek, in KiB */ |
23 | static const int cfq_back_max = 16 * 1024; | |
24 | /* penalty of a backwards seek */ | |
25 | static const int cfq_back_penalty = 2; | |
64100099 | 26 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 27 | static int cfq_slice_async = HZ / 25; |
64100099 | 28 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 29 | static int cfq_slice_idle = HZ / 125; |
22e2c507 | 30 | |
d9e7620e | 31 | /* |
0871714e | 32 | * offset from end of service tree |
d9e7620e | 33 | */ |
0871714e | 34 | #define CFQ_IDLE_DELAY (HZ / 5) |
d9e7620e JA |
35 | |
36 | /* | |
37 | * below this threshold, we consider thinktime immediate | |
38 | */ | |
39 | #define CFQ_MIN_TT (2) | |
40 | ||
22e2c507 | 41 | #define CFQ_SLICE_SCALE (5) |
45333d5a | 42 | #define CFQ_HW_QUEUE_MIN (5) |
22e2c507 | 43 | |
fe094d98 JA |
44 | #define RQ_CIC(rq) \ |
45 | ((struct cfq_io_context *) (rq)->elevator_private) | |
7b679138 | 46 | #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) |
1da177e4 | 47 | |
e18b890b CL |
48 | static struct kmem_cache *cfq_pool; |
49 | static struct kmem_cache *cfq_ioc_pool; | |
1da177e4 | 50 | |
245b2e70 | 51 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
334e94de | 52 | static struct completion *ioc_gone; |
9a11b4ed | 53 | static DEFINE_SPINLOCK(ioc_gone_lock); |
334e94de | 54 | |
22e2c507 JA |
55 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
56 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
22e2c507 JA |
57 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
58 | ||
206dc69b JA |
59 | #define sample_valid(samples) ((samples) > 80) |
60 | ||
cc09e299 JA |
61 | /* |
62 | * Most of our rbtree usage is for sorting with min extraction, so | |
63 | * if we cache the leftmost node we don't have to walk down the tree | |
64 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should | |
65 | * move this into the elevator for the rq sorting as well. | |
66 | */ | |
67 | struct cfq_rb_root { | |
68 | struct rb_root rb; | |
69 | struct rb_node *left; | |
70 | }; | |
71 | #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, } | |
72 | ||
6118b70b JA |
73 | /* |
74 | * Per process-grouping structure | |
75 | */ | |
76 | struct cfq_queue { | |
77 | /* reference count */ | |
78 | atomic_t ref; | |
79 | /* various state flags, see below */ | |
80 | unsigned int flags; | |
81 | /* parent cfq_data */ | |
82 | struct cfq_data *cfqd; | |
83 | /* service_tree member */ | |
84 | struct rb_node rb_node; | |
85 | /* service_tree key */ | |
86 | unsigned long rb_key; | |
87 | /* prio tree member */ | |
88 | struct rb_node p_node; | |
89 | /* prio tree root we belong to, if any */ | |
90 | struct rb_root *p_root; | |
91 | /* sorted list of pending requests */ | |
92 | struct rb_root sort_list; | |
93 | /* if fifo isn't expired, next request to serve */ | |
94 | struct request *next_rq; | |
95 | /* requests queued in sort_list */ | |
96 | int queued[2]; | |
97 | /* currently allocated requests */ | |
98 | int allocated[2]; | |
99 | /* fifo list of requests in sort_list */ | |
100 | struct list_head fifo; | |
101 | ||
102 | unsigned long slice_end; | |
103 | long slice_resid; | |
104 | unsigned int slice_dispatch; | |
105 | ||
106 | /* pending metadata requests */ | |
107 | int meta_pending; | |
108 | /* number of requests that are on the dispatch list or inside driver */ | |
109 | int dispatched; | |
110 | ||
111 | /* io prio of this group */ | |
112 | unsigned short ioprio, org_ioprio; | |
113 | unsigned short ioprio_class, org_ioprio_class; | |
114 | ||
b2c18e1e JM |
115 | unsigned int seek_samples; |
116 | u64 seek_total; | |
117 | sector_t seek_mean; | |
118 | sector_t last_request_pos; | |
119 | ||
6118b70b | 120 | pid_t pid; |
df5fe3e8 JM |
121 | |
122 | struct cfq_queue *new_cfqq; | |
6118b70b JA |
123 | }; |
124 | ||
22e2c507 JA |
125 | /* |
126 | * Per block device queue structure | |
127 | */ | |
1da177e4 | 128 | struct cfq_data { |
165125e1 | 129 | struct request_queue *queue; |
22e2c507 JA |
130 | |
131 | /* | |
132 | * rr list of queues with requests and the count of them | |
133 | */ | |
cc09e299 | 134 | struct cfq_rb_root service_tree; |
a36e71f9 JA |
135 | |
136 | /* | |
137 | * Each priority tree is sorted by next_request position. These | |
138 | * trees are used when determining if two or more queues are | |
139 | * interleaving requests (see cfq_close_cooperator). | |
140 | */ | |
141 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
142 | ||
22e2c507 JA |
143 | unsigned int busy_queues; |
144 | ||
5ad531db | 145 | int rq_in_driver[2]; |
3ed9a296 | 146 | int sync_flight; |
45333d5a AC |
147 | |
148 | /* | |
149 | * queue-depth detection | |
150 | */ | |
151 | int rq_queued; | |
25776e35 | 152 | int hw_tag; |
45333d5a AC |
153 | int hw_tag_samples; |
154 | int rq_in_driver_peak; | |
1da177e4 | 155 | |
22e2c507 JA |
156 | /* |
157 | * idle window management | |
158 | */ | |
159 | struct timer_list idle_slice_timer; | |
23e018a1 | 160 | struct work_struct unplug_work; |
1da177e4 | 161 | |
22e2c507 JA |
162 | struct cfq_queue *active_queue; |
163 | struct cfq_io_context *active_cic; | |
22e2c507 | 164 | |
c2dea2d1 VT |
165 | /* |
166 | * async queue for each priority case | |
167 | */ | |
168 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
169 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 170 | |
6d048f53 | 171 | sector_t last_position; |
1da177e4 | 172 | |
1da177e4 LT |
173 | /* |
174 | * tunables, see top of file | |
175 | */ | |
176 | unsigned int cfq_quantum; | |
22e2c507 | 177 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
178 | unsigned int cfq_back_penalty; |
179 | unsigned int cfq_back_max; | |
22e2c507 JA |
180 | unsigned int cfq_slice[2]; |
181 | unsigned int cfq_slice_async_rq; | |
182 | unsigned int cfq_slice_idle; | |
963b72fc | 183 | unsigned int cfq_latency; |
d9ff4187 AV |
184 | |
185 | struct list_head cic_list; | |
1da177e4 | 186 | |
6118b70b JA |
187 | /* |
188 | * Fallback dummy cfqq for extreme OOM conditions | |
189 | */ | |
190 | struct cfq_queue oom_cfqq; | |
365722bb VG |
191 | |
192 | unsigned long last_end_sync_rq; | |
1da177e4 LT |
193 | }; |
194 | ||
3b18152c | 195 | enum cfqq_state_flags { |
b0b8d749 JA |
196 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
197 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
b029195d | 198 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
b0b8d749 | 199 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
b0b8d749 JA |
200 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
201 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
202 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
44f7c160 | 203 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 204 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
b3b6d040 | 205 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
3b18152c JA |
206 | }; |
207 | ||
208 | #define CFQ_CFQQ_FNS(name) \ | |
209 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
210 | { \ | |
fe094d98 | 211 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
212 | } \ |
213 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
214 | { \ | |
fe094d98 | 215 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
216 | } \ |
217 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
218 | { \ | |
fe094d98 | 219 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
3b18152c JA |
220 | } |
221 | ||
222 | CFQ_CFQQ_FNS(on_rr); | |
223 | CFQ_CFQQ_FNS(wait_request); | |
b029195d | 224 | CFQ_CFQQ_FNS(must_dispatch); |
3b18152c | 225 | CFQ_CFQQ_FNS(must_alloc_slice); |
3b18152c JA |
226 | CFQ_CFQQ_FNS(fifo_expire); |
227 | CFQ_CFQQ_FNS(idle_window); | |
228 | CFQ_CFQQ_FNS(prio_changed); | |
44f7c160 | 229 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 230 | CFQ_CFQQ_FNS(sync); |
a36e71f9 | 231 | CFQ_CFQQ_FNS(coop); |
3b18152c JA |
232 | #undef CFQ_CFQQ_FNS |
233 | ||
7b679138 JA |
234 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
235 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
236 | #define cfq_log(cfqd, fmt, args...) \ | |
237 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
238 | ||
165125e1 | 239 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
a6151c3a | 240 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
fd0928df | 241 | struct io_context *, gfp_t); |
4ac845a2 | 242 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
243 | struct io_context *); |
244 | ||
5ad531db JA |
245 | static inline int rq_in_driver(struct cfq_data *cfqd) |
246 | { | |
247 | return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; | |
248 | } | |
249 | ||
91fac317 | 250 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
a6151c3a | 251 | bool is_sync) |
91fac317 | 252 | { |
a6151c3a | 253 | return cic->cfqq[is_sync]; |
91fac317 VT |
254 | } |
255 | ||
256 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
a6151c3a | 257 | struct cfq_queue *cfqq, bool is_sync) |
91fac317 | 258 | { |
a6151c3a | 259 | cic->cfqq[is_sync] = cfqq; |
91fac317 VT |
260 | } |
261 | ||
262 | /* | |
263 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
264 | * set (in which case it could also be direct WRITE). | |
265 | */ | |
a6151c3a | 266 | static inline bool cfq_bio_sync(struct bio *bio) |
91fac317 | 267 | { |
a6151c3a | 268 | return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); |
91fac317 | 269 | } |
1da177e4 | 270 | |
99f95e52 AM |
271 | /* |
272 | * scheduler run of queue, if there are requests pending and no one in the | |
273 | * driver that will restart queueing | |
274 | */ | |
23e018a1 | 275 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
99f95e52 | 276 | { |
7b679138 JA |
277 | if (cfqd->busy_queues) { |
278 | cfq_log(cfqd, "schedule dispatch"); | |
23e018a1 | 279 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
7b679138 | 280 | } |
99f95e52 AM |
281 | } |
282 | ||
165125e1 | 283 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
284 | { |
285 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
286 | ||
b4878f24 | 287 | return !cfqd->busy_queues; |
99f95e52 AM |
288 | } |
289 | ||
44f7c160 JA |
290 | /* |
291 | * Scale schedule slice based on io priority. Use the sync time slice only | |
292 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
293 | * io only, should not get full sync slice length. | |
294 | */ | |
a6151c3a | 295 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
d9e7620e | 296 | unsigned short prio) |
44f7c160 | 297 | { |
d9e7620e | 298 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 299 | |
d9e7620e JA |
300 | WARN_ON(prio >= IOPRIO_BE_NR); |
301 | ||
302 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
303 | } | |
44f7c160 | 304 | |
d9e7620e JA |
305 | static inline int |
306 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
307 | { | |
308 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
309 | } |
310 | ||
311 | static inline void | |
312 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
313 | { | |
314 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
7b679138 | 315 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
44f7c160 JA |
316 | } |
317 | ||
318 | /* | |
319 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
320 | * isn't valid until the first request from the dispatch is activated | |
321 | * and the slice time set. | |
322 | */ | |
a6151c3a | 323 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
44f7c160 JA |
324 | { |
325 | if (cfq_cfqq_slice_new(cfqq)) | |
326 | return 0; | |
327 | if (time_before(jiffies, cfqq->slice_end)) | |
328 | return 0; | |
329 | ||
330 | return 1; | |
331 | } | |
332 | ||
1da177e4 | 333 | /* |
5e705374 | 334 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 335 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 336 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 337 | */ |
5e705374 JA |
338 | static struct request * |
339 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
1da177e4 LT |
340 | { |
341 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 342 | unsigned long back_max; |
e8a99053 AM |
343 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
344 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
345 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 346 | |
5e705374 JA |
347 | if (rq1 == NULL || rq1 == rq2) |
348 | return rq2; | |
349 | if (rq2 == NULL) | |
350 | return rq1; | |
9c2c38a1 | 351 | |
5e705374 JA |
352 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
353 | return rq1; | |
354 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
355 | return rq2; | |
374f84ac JA |
356 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
357 | return rq1; | |
358 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
359 | return rq2; | |
1da177e4 | 360 | |
83096ebf TH |
361 | s1 = blk_rq_pos(rq1); |
362 | s2 = blk_rq_pos(rq2); | |
1da177e4 | 363 | |
6d048f53 | 364 | last = cfqd->last_position; |
1da177e4 | 365 | |
1da177e4 LT |
366 | /* |
367 | * by definition, 1KiB is 2 sectors | |
368 | */ | |
369 | back_max = cfqd->cfq_back_max * 2; | |
370 | ||
371 | /* | |
372 | * Strict one way elevator _except_ in the case where we allow | |
373 | * short backward seeks which are biased as twice the cost of a | |
374 | * similar forward seek. | |
375 | */ | |
376 | if (s1 >= last) | |
377 | d1 = s1 - last; | |
378 | else if (s1 + back_max >= last) | |
379 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
380 | else | |
e8a99053 | 381 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
382 | |
383 | if (s2 >= last) | |
384 | d2 = s2 - last; | |
385 | else if (s2 + back_max >= last) | |
386 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
387 | else | |
e8a99053 | 388 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
389 | |
390 | /* Found required data */ | |
e8a99053 AM |
391 | |
392 | /* | |
393 | * By doing switch() on the bit mask "wrap" we avoid having to | |
394 | * check two variables for all permutations: --> faster! | |
395 | */ | |
396 | switch (wrap) { | |
5e705374 | 397 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 398 | if (d1 < d2) |
5e705374 | 399 | return rq1; |
e8a99053 | 400 | else if (d2 < d1) |
5e705374 | 401 | return rq2; |
e8a99053 AM |
402 | else { |
403 | if (s1 >= s2) | |
5e705374 | 404 | return rq1; |
e8a99053 | 405 | else |
5e705374 | 406 | return rq2; |
e8a99053 | 407 | } |
1da177e4 | 408 | |
e8a99053 | 409 | case CFQ_RQ2_WRAP: |
5e705374 | 410 | return rq1; |
e8a99053 | 411 | case CFQ_RQ1_WRAP: |
5e705374 JA |
412 | return rq2; |
413 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
414 | default: |
415 | /* | |
416 | * Since both rqs are wrapped, | |
417 | * start with the one that's further behind head | |
418 | * (--> only *one* back seek required), | |
419 | * since back seek takes more time than forward. | |
420 | */ | |
421 | if (s1 <= s2) | |
5e705374 | 422 | return rq1; |
1da177e4 | 423 | else |
5e705374 | 424 | return rq2; |
1da177e4 LT |
425 | } |
426 | } | |
427 | ||
498d3aa2 JA |
428 | /* |
429 | * The below is leftmost cache rbtree addon | |
430 | */ | |
0871714e | 431 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 JA |
432 | { |
433 | if (!root->left) | |
434 | root->left = rb_first(&root->rb); | |
435 | ||
0871714e JA |
436 | if (root->left) |
437 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
438 | ||
439 | return NULL; | |
cc09e299 JA |
440 | } |
441 | ||
a36e71f9 JA |
442 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
443 | { | |
444 | rb_erase(n, root); | |
445 | RB_CLEAR_NODE(n); | |
446 | } | |
447 | ||
cc09e299 JA |
448 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
449 | { | |
450 | if (root->left == n) | |
451 | root->left = NULL; | |
a36e71f9 | 452 | rb_erase_init(n, &root->rb); |
cc09e299 JA |
453 | } |
454 | ||
1da177e4 LT |
455 | /* |
456 | * would be nice to take fifo expire time into account as well | |
457 | */ | |
5e705374 JA |
458 | static struct request * |
459 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
460 | struct request *last) | |
1da177e4 | 461 | { |
21183b07 JA |
462 | struct rb_node *rbnext = rb_next(&last->rb_node); |
463 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 464 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 465 | |
21183b07 | 466 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
467 | |
468 | if (rbprev) | |
5e705374 | 469 | prev = rb_entry_rq(rbprev); |
1da177e4 | 470 | |
21183b07 | 471 | if (rbnext) |
5e705374 | 472 | next = rb_entry_rq(rbnext); |
21183b07 JA |
473 | else { |
474 | rbnext = rb_first(&cfqq->sort_list); | |
475 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 476 | next = rb_entry_rq(rbnext); |
21183b07 | 477 | } |
1da177e4 | 478 | |
21183b07 | 479 | return cfq_choose_req(cfqd, next, prev); |
1da177e4 LT |
480 | } |
481 | ||
d9e7620e JA |
482 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
483 | struct cfq_queue *cfqq) | |
1da177e4 | 484 | { |
d9e7620e JA |
485 | /* |
486 | * just an approximation, should be ok. | |
487 | */ | |
67e6b49e JA |
488 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
489 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
490 | } |
491 | ||
498d3aa2 JA |
492 | /* |
493 | * The cfqd->service_tree holds all pending cfq_queue's that have | |
494 | * requests waiting to be processed. It is sorted in the order that | |
495 | * we will service the queues. | |
496 | */ | |
a36e71f9 | 497 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 498 | bool add_front) |
d9e7620e | 499 | { |
0871714e JA |
500 | struct rb_node **p, *parent; |
501 | struct cfq_queue *__cfqq; | |
d9e7620e | 502 | unsigned long rb_key; |
498d3aa2 | 503 | int left; |
d9e7620e | 504 | |
0871714e JA |
505 | if (cfq_class_idle(cfqq)) { |
506 | rb_key = CFQ_IDLE_DELAY; | |
507 | parent = rb_last(&cfqd->service_tree.rb); | |
508 | if (parent && parent != &cfqq->rb_node) { | |
509 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
510 | rb_key += __cfqq->rb_key; | |
511 | } else | |
512 | rb_key += jiffies; | |
513 | } else if (!add_front) { | |
b9c8946b JA |
514 | /* |
515 | * Get our rb key offset. Subtract any residual slice | |
516 | * value carried from last service. A negative resid | |
517 | * count indicates slice overrun, and this should position | |
518 | * the next service time further away in the tree. | |
519 | */ | |
edd75ffd | 520 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
b9c8946b | 521 | rb_key -= cfqq->slice_resid; |
edd75ffd | 522 | cfqq->slice_resid = 0; |
48e025e6 CZ |
523 | } else { |
524 | rb_key = -HZ; | |
525 | __cfqq = cfq_rb_first(&cfqd->service_tree); | |
526 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; | |
527 | } | |
1da177e4 | 528 | |
d9e7620e | 529 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 530 | /* |
d9e7620e | 531 | * same position, nothing more to do |
99f9628a | 532 | */ |
d9e7620e JA |
533 | if (rb_key == cfqq->rb_key) |
534 | return; | |
1da177e4 | 535 | |
cc09e299 | 536 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
1da177e4 | 537 | } |
d9e7620e | 538 | |
498d3aa2 | 539 | left = 1; |
0871714e JA |
540 | parent = NULL; |
541 | p = &cfqd->service_tree.rb.rb_node; | |
d9e7620e | 542 | while (*p) { |
67060e37 | 543 | struct rb_node **n; |
cc09e299 | 544 | |
d9e7620e JA |
545 | parent = *p; |
546 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
547 | ||
0c534e0a JA |
548 | /* |
549 | * sort RT queues first, we always want to give | |
67060e37 JA |
550 | * preference to them. IDLE queues goes to the back. |
551 | * after that, sort on the next service time. | |
0c534e0a JA |
552 | */ |
553 | if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) | |
67060e37 | 554 | n = &(*p)->rb_left; |
0c534e0a | 555 | else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) |
67060e37 JA |
556 | n = &(*p)->rb_right; |
557 | else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) | |
558 | n = &(*p)->rb_left; | |
559 | else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) | |
560 | n = &(*p)->rb_right; | |
48e025e6 | 561 | else if (time_before(rb_key, __cfqq->rb_key)) |
67060e37 JA |
562 | n = &(*p)->rb_left; |
563 | else | |
564 | n = &(*p)->rb_right; | |
565 | ||
566 | if (n == &(*p)->rb_right) | |
cc09e299 | 567 | left = 0; |
67060e37 JA |
568 | |
569 | p = n; | |
d9e7620e JA |
570 | } |
571 | ||
cc09e299 JA |
572 | if (left) |
573 | cfqd->service_tree.left = &cfqq->rb_node; | |
574 | ||
d9e7620e JA |
575 | cfqq->rb_key = rb_key; |
576 | rb_link_node(&cfqq->rb_node, parent, p); | |
cc09e299 | 577 | rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); |
1da177e4 LT |
578 | } |
579 | ||
a36e71f9 | 580 | static struct cfq_queue * |
f2d1f0ae JA |
581 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
582 | sector_t sector, struct rb_node **ret_parent, | |
583 | struct rb_node ***rb_link) | |
a36e71f9 | 584 | { |
a36e71f9 JA |
585 | struct rb_node **p, *parent; |
586 | struct cfq_queue *cfqq = NULL; | |
587 | ||
588 | parent = NULL; | |
589 | p = &root->rb_node; | |
590 | while (*p) { | |
591 | struct rb_node **n; | |
592 | ||
593 | parent = *p; | |
594 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
595 | ||
596 | /* | |
597 | * Sort strictly based on sector. Smallest to the left, | |
598 | * largest to the right. | |
599 | */ | |
2e46e8b2 | 600 | if (sector > blk_rq_pos(cfqq->next_rq)) |
a36e71f9 | 601 | n = &(*p)->rb_right; |
2e46e8b2 | 602 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
a36e71f9 JA |
603 | n = &(*p)->rb_left; |
604 | else | |
605 | break; | |
606 | p = n; | |
3ac6c9f8 | 607 | cfqq = NULL; |
a36e71f9 JA |
608 | } |
609 | ||
610 | *ret_parent = parent; | |
611 | if (rb_link) | |
612 | *rb_link = p; | |
3ac6c9f8 | 613 | return cfqq; |
a36e71f9 JA |
614 | } |
615 | ||
616 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
617 | { | |
a36e71f9 JA |
618 | struct rb_node **p, *parent; |
619 | struct cfq_queue *__cfqq; | |
620 | ||
f2d1f0ae JA |
621 | if (cfqq->p_root) { |
622 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
623 | cfqq->p_root = NULL; | |
624 | } | |
a36e71f9 JA |
625 | |
626 | if (cfq_class_idle(cfqq)) | |
627 | return; | |
628 | if (!cfqq->next_rq) | |
629 | return; | |
630 | ||
f2d1f0ae | 631 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
2e46e8b2 TH |
632 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
633 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
3ac6c9f8 JA |
634 | if (!__cfqq) { |
635 | rb_link_node(&cfqq->p_node, parent, p); | |
f2d1f0ae JA |
636 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
637 | } else | |
638 | cfqq->p_root = NULL; | |
a36e71f9 JA |
639 | } |
640 | ||
498d3aa2 JA |
641 | /* |
642 | * Update cfqq's position in the service tree. | |
643 | */ | |
edd75ffd | 644 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 645 | { |
6d048f53 JA |
646 | /* |
647 | * Resorting requires the cfqq to be on the RR list already. | |
648 | */ | |
a36e71f9 | 649 | if (cfq_cfqq_on_rr(cfqq)) { |
edd75ffd | 650 | cfq_service_tree_add(cfqd, cfqq, 0); |
a36e71f9 JA |
651 | cfq_prio_tree_add(cfqd, cfqq); |
652 | } | |
6d048f53 JA |
653 | } |
654 | ||
1da177e4 LT |
655 | /* |
656 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 657 | * the pending list according to last request service |
1da177e4 | 658 | */ |
febffd61 | 659 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 660 | { |
7b679138 | 661 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
3b18152c JA |
662 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
663 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
664 | cfqd->busy_queues++; |
665 | ||
edd75ffd | 666 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
667 | } |
668 | ||
498d3aa2 JA |
669 | /* |
670 | * Called when the cfqq no longer has requests pending, remove it from | |
671 | * the service tree. | |
672 | */ | |
febffd61 | 673 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 674 | { |
7b679138 | 675 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
3b18152c JA |
676 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
677 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 678 | |
cc09e299 JA |
679 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) |
680 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); | |
f2d1f0ae JA |
681 | if (cfqq->p_root) { |
682 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
683 | cfqq->p_root = NULL; | |
684 | } | |
d9e7620e | 685 | |
1da177e4 LT |
686 | BUG_ON(!cfqd->busy_queues); |
687 | cfqd->busy_queues--; | |
688 | } | |
689 | ||
690 | /* | |
691 | * rb tree support functions | |
692 | */ | |
febffd61 | 693 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 694 | { |
5e705374 | 695 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 696 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 697 | const int sync = rq_is_sync(rq); |
1da177e4 | 698 | |
b4878f24 JA |
699 | BUG_ON(!cfqq->queued[sync]); |
700 | cfqq->queued[sync]--; | |
1da177e4 | 701 | |
5e705374 | 702 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 703 | |
dd67d051 | 704 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 705 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
706 | } |
707 | ||
5e705374 | 708 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 709 | { |
5e705374 | 710 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 711 | struct cfq_data *cfqd = cfqq->cfqd; |
a36e71f9 | 712 | struct request *__alias, *prev; |
1da177e4 | 713 | |
5380a101 | 714 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
715 | |
716 | /* | |
717 | * looks a little odd, but the first insert might return an alias. | |
718 | * if that happens, put the alias on the dispatch list | |
719 | */ | |
21183b07 | 720 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 721 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
722 | |
723 | if (!cfq_cfqq_on_rr(cfqq)) | |
724 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
725 | |
726 | /* | |
727 | * check if this request is a better next-serve candidate | |
728 | */ | |
a36e71f9 | 729 | prev = cfqq->next_rq; |
5044eed4 | 730 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); |
a36e71f9 JA |
731 | |
732 | /* | |
733 | * adjust priority tree position, if ->next_rq changes | |
734 | */ | |
735 | if (prev != cfqq->next_rq) | |
736 | cfq_prio_tree_add(cfqd, cfqq); | |
737 | ||
5044eed4 | 738 | BUG_ON(!cfqq->next_rq); |
1da177e4 LT |
739 | } |
740 | ||
febffd61 | 741 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 742 | { |
5380a101 JA |
743 | elv_rb_del(&cfqq->sort_list, rq); |
744 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 745 | cfq_add_rq_rb(rq); |
1da177e4 LT |
746 | } |
747 | ||
206dc69b JA |
748 | static struct request * |
749 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 750 | { |
206dc69b | 751 | struct task_struct *tsk = current; |
91fac317 | 752 | struct cfq_io_context *cic; |
206dc69b | 753 | struct cfq_queue *cfqq; |
1da177e4 | 754 | |
4ac845a2 | 755 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
756 | if (!cic) |
757 | return NULL; | |
758 | ||
759 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
760 | if (cfqq) { |
761 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
762 | ||
21183b07 | 763 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 764 | } |
1da177e4 | 765 | |
1da177e4 LT |
766 | return NULL; |
767 | } | |
768 | ||
165125e1 | 769 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 770 | { |
22e2c507 | 771 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 772 | |
5ad531db | 773 | cfqd->rq_in_driver[rq_is_sync(rq)]++; |
7b679138 | 774 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
5ad531db | 775 | rq_in_driver(cfqd)); |
25776e35 | 776 | |
5b93629b | 777 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1da177e4 LT |
778 | } |
779 | ||
165125e1 | 780 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 781 | { |
b4878f24 | 782 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5ad531db | 783 | const int sync = rq_is_sync(rq); |
b4878f24 | 784 | |
5ad531db JA |
785 | WARN_ON(!cfqd->rq_in_driver[sync]); |
786 | cfqd->rq_in_driver[sync]--; | |
7b679138 | 787 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
5ad531db | 788 | rq_in_driver(cfqd)); |
1da177e4 LT |
789 | } |
790 | ||
b4878f24 | 791 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 792 | { |
5e705374 | 793 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 794 | |
5e705374 JA |
795 | if (cfqq->next_rq == rq) |
796 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 797 | |
b4878f24 | 798 | list_del_init(&rq->queuelist); |
5e705374 | 799 | cfq_del_rq_rb(rq); |
374f84ac | 800 | |
45333d5a | 801 | cfqq->cfqd->rq_queued--; |
374f84ac JA |
802 | if (rq_is_meta(rq)) { |
803 | WARN_ON(!cfqq->meta_pending); | |
804 | cfqq->meta_pending--; | |
805 | } | |
1da177e4 LT |
806 | } |
807 | ||
165125e1 JA |
808 | static int cfq_merge(struct request_queue *q, struct request **req, |
809 | struct bio *bio) | |
1da177e4 LT |
810 | { |
811 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
812 | struct request *__rq; | |
1da177e4 | 813 | |
206dc69b | 814 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 815 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
816 | *req = __rq; |
817 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
818 | } |
819 | ||
820 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
821 | } |
822 | ||
165125e1 | 823 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 824 | int type) |
1da177e4 | 825 | { |
21183b07 | 826 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 827 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 828 | |
5e705374 | 829 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 830 | } |
1da177e4 LT |
831 | } |
832 | ||
833 | static void | |
165125e1 | 834 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
835 | struct request *next) |
836 | { | |
22e2c507 JA |
837 | /* |
838 | * reposition in fifo if next is older than rq | |
839 | */ | |
840 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
30996f40 | 841 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
22e2c507 | 842 | list_move(&rq->queuelist, &next->queuelist); |
30996f40 JA |
843 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
844 | } | |
22e2c507 | 845 | |
b4878f24 | 846 | cfq_remove_request(next); |
22e2c507 JA |
847 | } |
848 | ||
165125e1 | 849 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
850 | struct bio *bio) |
851 | { | |
852 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 853 | struct cfq_io_context *cic; |
da775265 | 854 | struct cfq_queue *cfqq; |
da775265 JA |
855 | |
856 | /* | |
ec8acb69 | 857 | * Disallow merge of a sync bio into an async request. |
da775265 | 858 | */ |
91fac317 | 859 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
a6151c3a | 860 | return false; |
da775265 JA |
861 | |
862 | /* | |
719d3402 JA |
863 | * Lookup the cfqq that this bio will be queued with. Allow |
864 | * merge only if rq is queued there. | |
da775265 | 865 | */ |
4ac845a2 | 866 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 | 867 | if (!cic) |
a6151c3a | 868 | return false; |
719d3402 | 869 | |
91fac317 | 870 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
a6151c3a | 871 | return cfqq == RQ_CFQQ(rq); |
da775265 JA |
872 | } |
873 | ||
febffd61 JA |
874 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
875 | struct cfq_queue *cfqq) | |
22e2c507 JA |
876 | { |
877 | if (cfqq) { | |
7b679138 | 878 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
22e2c507 | 879 | cfqq->slice_end = 0; |
2f5cb738 JA |
880 | cfqq->slice_dispatch = 0; |
881 | ||
2f5cb738 | 882 | cfq_clear_cfqq_wait_request(cfqq); |
b029195d | 883 | cfq_clear_cfqq_must_dispatch(cfqq); |
3b18152c JA |
884 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
885 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 886 | cfq_mark_cfqq_slice_new(cfqq); |
2f5cb738 JA |
887 | |
888 | del_timer(&cfqd->idle_slice_timer); | |
22e2c507 JA |
889 | } |
890 | ||
891 | cfqd->active_queue = cfqq; | |
892 | } | |
893 | ||
7b14e3b5 JA |
894 | /* |
895 | * current cfqq expired its slice (or was too idle), select new one | |
896 | */ | |
897 | static void | |
898 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
a6151c3a | 899 | bool timed_out) |
7b14e3b5 | 900 | { |
7b679138 JA |
901 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
902 | ||
7b14e3b5 JA |
903 | if (cfq_cfqq_wait_request(cfqq)) |
904 | del_timer(&cfqd->idle_slice_timer); | |
905 | ||
7b14e3b5 JA |
906 | cfq_clear_cfqq_wait_request(cfqq); |
907 | ||
908 | /* | |
6084cdda | 909 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 910 | */ |
7b679138 | 911 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
c5b680f3 | 912 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b679138 JA |
913 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
914 | } | |
7b14e3b5 | 915 | |
edd75ffd | 916 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
917 | |
918 | if (cfqq == cfqd->active_queue) | |
919 | cfqd->active_queue = NULL; | |
920 | ||
921 | if (cfqd->active_cic) { | |
922 | put_io_context(cfqd->active_cic->ioc); | |
923 | cfqd->active_cic = NULL; | |
924 | } | |
7b14e3b5 JA |
925 | } |
926 | ||
a6151c3a | 927 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
7b14e3b5 JA |
928 | { |
929 | struct cfq_queue *cfqq = cfqd->active_queue; | |
930 | ||
931 | if (cfqq) | |
6084cdda | 932 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
933 | } |
934 | ||
498d3aa2 JA |
935 | /* |
936 | * Get next queue for service. Unless we have a queue preemption, | |
937 | * we'll simply select the first cfqq in the service tree. | |
938 | */ | |
6d048f53 | 939 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 940 | { |
edd75ffd JA |
941 | if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) |
942 | return NULL; | |
d9e7620e | 943 | |
0871714e | 944 | return cfq_rb_first(&cfqd->service_tree); |
6d048f53 JA |
945 | } |
946 | ||
498d3aa2 JA |
947 | /* |
948 | * Get and set a new active queue for service. | |
949 | */ | |
a36e71f9 JA |
950 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
951 | struct cfq_queue *cfqq) | |
6d048f53 | 952 | { |
b3b6d040 | 953 | if (!cfqq) |
a36e71f9 | 954 | cfqq = cfq_get_next_queue(cfqd); |
6d048f53 | 955 | |
22e2c507 | 956 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 957 | return cfqq; |
22e2c507 JA |
958 | } |
959 | ||
d9e7620e JA |
960 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
961 | struct request *rq) | |
962 | { | |
83096ebf TH |
963 | if (blk_rq_pos(rq) >= cfqd->last_position) |
964 | return blk_rq_pos(rq) - cfqd->last_position; | |
d9e7620e | 965 | else |
83096ebf | 966 | return cfqd->last_position - blk_rq_pos(rq); |
d9e7620e JA |
967 | } |
968 | ||
b2c18e1e JM |
969 | #define CFQQ_SEEK_THR 8 * 1024 |
970 | #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR) | |
04dc6e71 | 971 | |
b2c18e1e JM |
972 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
973 | struct request *rq) | |
6d048f53 | 974 | { |
b2c18e1e | 975 | sector_t sdist = cfqq->seek_mean; |
6d048f53 | 976 | |
b2c18e1e JM |
977 | if (!sample_valid(cfqq->seek_samples)) |
978 | sdist = CFQQ_SEEK_THR; | |
6d048f53 | 979 | |
04dc6e71 | 980 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
6d048f53 JA |
981 | } |
982 | ||
a36e71f9 JA |
983 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
984 | struct cfq_queue *cur_cfqq) | |
985 | { | |
f2d1f0ae | 986 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
a36e71f9 JA |
987 | struct rb_node *parent, *node; |
988 | struct cfq_queue *__cfqq; | |
989 | sector_t sector = cfqd->last_position; | |
990 | ||
991 | if (RB_EMPTY_ROOT(root)) | |
992 | return NULL; | |
993 | ||
994 | /* | |
995 | * First, if we find a request starting at the end of the last | |
996 | * request, choose it. | |
997 | */ | |
f2d1f0ae | 998 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
a36e71f9 JA |
999 | if (__cfqq) |
1000 | return __cfqq; | |
1001 | ||
1002 | /* | |
1003 | * If the exact sector wasn't found, the parent of the NULL leaf | |
1004 | * will contain the closest sector. | |
1005 | */ | |
1006 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
b2c18e1e | 1007 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1008 | return __cfqq; |
1009 | ||
2e46e8b2 | 1010 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
a36e71f9 JA |
1011 | node = rb_next(&__cfqq->p_node); |
1012 | else | |
1013 | node = rb_prev(&__cfqq->p_node); | |
1014 | if (!node) | |
1015 | return NULL; | |
1016 | ||
1017 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
b2c18e1e | 1018 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1019 | return __cfqq; |
1020 | ||
1021 | return NULL; | |
1022 | } | |
1023 | ||
1024 | /* | |
1025 | * cfqd - obvious | |
1026 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1027 | * closely cooperating with itself. | |
1028 | * | |
1029 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1030 | * one request, and that cfqd->last_position reflects a position on the disk | |
1031 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1032 | * assumption. | |
1033 | */ | |
1034 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
b3b6d040 | 1035 | struct cfq_queue *cur_cfqq) |
6d048f53 | 1036 | { |
a36e71f9 JA |
1037 | struct cfq_queue *cfqq; |
1038 | ||
6d048f53 | 1039 | /* |
d9e7620e JA |
1040 | * We should notice if some of the queues are cooperating, eg |
1041 | * working closely on the same area of the disk. In that case, | |
1042 | * we can group them together and don't waste time idling. | |
6d048f53 | 1043 | */ |
a36e71f9 JA |
1044 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1045 | if (!cfqq) | |
1046 | return NULL; | |
1047 | ||
df5fe3e8 JM |
1048 | /* |
1049 | * It only makes sense to merge sync queues. | |
1050 | */ | |
1051 | if (!cfq_cfqq_sync(cfqq)) | |
1052 | return NULL; | |
1053 | ||
a36e71f9 | 1054 | return cfqq; |
6d048f53 JA |
1055 | } |
1056 | ||
6d048f53 | 1057 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 1058 | { |
1792669c | 1059 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 1060 | struct cfq_io_context *cic; |
7b14e3b5 JA |
1061 | unsigned long sl; |
1062 | ||
a68bbddb | 1063 | /* |
f7d7b7a7 JA |
1064 | * SSD device without seek penalty, disable idling. But only do so |
1065 | * for devices that support queuing, otherwise we still have a problem | |
1066 | * with sync vs async workloads. | |
a68bbddb | 1067 | */ |
f7d7b7a7 | 1068 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
a68bbddb JA |
1069 | return; |
1070 | ||
dd67d051 | 1071 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 1072 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
1073 | |
1074 | /* | |
1075 | * idle is disabled, either manually or by past process history | |
1076 | */ | |
6d048f53 JA |
1077 | if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
1078 | return; | |
1079 | ||
7b679138 JA |
1080 | /* |
1081 | * still requests with the driver, don't idle | |
1082 | */ | |
5ad531db | 1083 | if (rq_in_driver(cfqd)) |
7b679138 JA |
1084 | return; |
1085 | ||
22e2c507 JA |
1086 | /* |
1087 | * task has exited, don't wait | |
1088 | */ | |
206dc69b | 1089 | cic = cfqd->active_cic; |
66dac98e | 1090 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
1091 | return; |
1092 | ||
355b659c CZ |
1093 | /* |
1094 | * If our average think time is larger than the remaining time | |
1095 | * slice, then don't idle. This avoids overrunning the allotted | |
1096 | * time slice. | |
1097 | */ | |
1098 | if (sample_valid(cic->ttime_samples) && | |
1099 | (cfqq->slice_end - jiffies < cic->ttime_mean)) | |
1100 | return; | |
1101 | ||
3b18152c | 1102 | cfq_mark_cfqq_wait_request(cfqq); |
22e2c507 | 1103 | |
206dc69b JA |
1104 | /* |
1105 | * we don't want to idle for seeks, but we do want to allow | |
1106 | * fair distribution of slice time for a process doing back-to-back | |
1107 | * seeks. so allow a little bit of time for him to submit a new rq | |
1108 | */ | |
6d048f53 | 1109 | sl = cfqd->cfq_slice_idle; |
b2c18e1e | 1110 | if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)) |
d9e7620e | 1111 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
206dc69b | 1112 | |
7b14e3b5 | 1113 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
9481ffdc | 1114 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
1da177e4 LT |
1115 | } |
1116 | ||
498d3aa2 JA |
1117 | /* |
1118 | * Move request from internal lists to the request queue dispatch list. | |
1119 | */ | |
165125e1 | 1120 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 1121 | { |
3ed9a296 | 1122 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1123 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1124 | |
7b679138 JA |
1125 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
1126 | ||
06d21886 | 1127 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
5380a101 | 1128 | cfq_remove_request(rq); |
6d048f53 | 1129 | cfqq->dispatched++; |
5380a101 | 1130 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
1131 | |
1132 | if (cfq_cfqq_sync(cfqq)) | |
1133 | cfqd->sync_flight++; | |
1da177e4 LT |
1134 | } |
1135 | ||
1136 | /* | |
1137 | * return expired entry, or NULL to just start from scratch in rbtree | |
1138 | */ | |
febffd61 | 1139 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 | 1140 | { |
30996f40 | 1141 | struct request *rq = NULL; |
1da177e4 | 1142 | |
3b18152c | 1143 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 1144 | return NULL; |
cb887411 JA |
1145 | |
1146 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1147 | ||
89850f7e JA |
1148 | if (list_empty(&cfqq->fifo)) |
1149 | return NULL; | |
1da177e4 | 1150 | |
89850f7e | 1151 | rq = rq_entry_fifo(cfqq->fifo.next); |
30996f40 | 1152 | if (time_before(jiffies, rq_fifo_time(rq))) |
7b679138 | 1153 | rq = NULL; |
1da177e4 | 1154 | |
30996f40 | 1155 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
6d048f53 | 1156 | return rq; |
1da177e4 LT |
1157 | } |
1158 | ||
22e2c507 JA |
1159 | static inline int |
1160 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1161 | { | |
1162 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1163 | |
22e2c507 | 1164 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1165 | |
22e2c507 | 1166 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1167 | } |
1168 | ||
df5fe3e8 JM |
1169 | /* |
1170 | * Must be called with the queue_lock held. | |
1171 | */ | |
1172 | static int cfqq_process_refs(struct cfq_queue *cfqq) | |
1173 | { | |
1174 | int process_refs, io_refs; | |
1175 | ||
1176 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; | |
1177 | process_refs = atomic_read(&cfqq->ref) - io_refs; | |
1178 | BUG_ON(process_refs < 0); | |
1179 | return process_refs; | |
1180 | } | |
1181 | ||
1182 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) | |
1183 | { | |
1184 | int process_refs; | |
1185 | struct cfq_queue *__cfqq; | |
1186 | ||
1187 | /* Avoid a circular list and skip interim queue merges */ | |
1188 | while ((__cfqq = new_cfqq->new_cfqq)) { | |
1189 | if (__cfqq == cfqq) | |
1190 | return; | |
1191 | new_cfqq = __cfqq; | |
1192 | } | |
1193 | ||
1194 | process_refs = cfqq_process_refs(cfqq); | |
1195 | /* | |
1196 | * If the process for the cfqq has gone away, there is no | |
1197 | * sense in merging the queues. | |
1198 | */ | |
1199 | if (process_refs == 0) | |
1200 | return; | |
1201 | ||
1202 | cfqq->new_cfqq = new_cfqq; | |
1203 | atomic_add(process_refs, &new_cfqq->ref); | |
1204 | } | |
1205 | ||
22e2c507 | 1206 | /* |
498d3aa2 JA |
1207 | * Select a queue for service. If we have a current active queue, |
1208 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 1209 | */ |
1b5ed5e1 | 1210 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1211 | { |
a36e71f9 | 1212 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
1da177e4 | 1213 | |
22e2c507 JA |
1214 | cfqq = cfqd->active_queue; |
1215 | if (!cfqq) | |
1216 | goto new_queue; | |
1da177e4 | 1217 | |
22e2c507 | 1218 | /* |
6d048f53 | 1219 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 1220 | */ |
b029195d | 1221 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
3b18152c | 1222 | goto expire; |
1da177e4 | 1223 | |
22e2c507 | 1224 | /* |
6d048f53 JA |
1225 | * The active queue has requests and isn't expired, allow it to |
1226 | * dispatch. | |
22e2c507 | 1227 | */ |
dd67d051 | 1228 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1229 | goto keep_queue; |
6d048f53 | 1230 | |
a36e71f9 JA |
1231 | /* |
1232 | * If another queue has a request waiting within our mean seek | |
1233 | * distance, let it run. The expire code will check for close | |
1234 | * cooperators and put the close queue at the front of the service | |
df5fe3e8 | 1235 | * tree. If possible, merge the expiring queue with the new cfqq. |
a36e71f9 | 1236 | */ |
b3b6d040 | 1237 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
df5fe3e8 JM |
1238 | if (new_cfqq) { |
1239 | if (!cfqq->new_cfqq) | |
1240 | cfq_setup_merge(cfqq, new_cfqq); | |
a36e71f9 | 1241 | goto expire; |
df5fe3e8 | 1242 | } |
a36e71f9 | 1243 | |
6d048f53 JA |
1244 | /* |
1245 | * No requests pending. If the active queue still has requests in | |
1246 | * flight or is idling for a new request, allow either of these | |
1247 | * conditions to happen (or time out) before selecting a new queue. | |
1248 | */ | |
cc197479 JA |
1249 | if (timer_pending(&cfqd->idle_slice_timer) || |
1250 | (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { | |
caaa5f9f JA |
1251 | cfqq = NULL; |
1252 | goto keep_queue; | |
22e2c507 JA |
1253 | } |
1254 | ||
3b18152c | 1255 | expire: |
6084cdda | 1256 | cfq_slice_expired(cfqd, 0); |
3b18152c | 1257 | new_queue: |
a36e71f9 | 1258 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
22e2c507 | 1259 | keep_queue: |
3b18152c | 1260 | return cfqq; |
22e2c507 JA |
1261 | } |
1262 | ||
febffd61 | 1263 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1264 | { |
1265 | int dispatched = 0; | |
1266 | ||
1267 | while (cfqq->next_rq) { | |
1268 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1269 | dispatched++; | |
1270 | } | |
1271 | ||
1272 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1273 | return dispatched; | |
1274 | } | |
1275 | ||
498d3aa2 JA |
1276 | /* |
1277 | * Drain our current requests. Used for barriers and when switching | |
1278 | * io schedulers on-the-fly. | |
1279 | */ | |
d9e7620e | 1280 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1281 | { |
0871714e | 1282 | struct cfq_queue *cfqq; |
d9e7620e | 1283 | int dispatched = 0; |
1b5ed5e1 | 1284 | |
0871714e | 1285 | while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL) |
d9e7620e | 1286 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1b5ed5e1 | 1287 | |
6084cdda | 1288 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1289 | |
1290 | BUG_ON(cfqd->busy_queues); | |
1291 | ||
6923715a | 1292 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
1b5ed5e1 TH |
1293 | return dispatched; |
1294 | } | |
1295 | ||
0b182d61 | 1296 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2f5cb738 | 1297 | { |
2f5cb738 | 1298 | unsigned int max_dispatch; |
22e2c507 | 1299 | |
5ad531db JA |
1300 | /* |
1301 | * Drain async requests before we start sync IO | |
1302 | */ | |
1303 | if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) | |
0b182d61 | 1304 | return false; |
5ad531db | 1305 | |
2f5cb738 JA |
1306 | /* |
1307 | * If this is an async queue and we have sync IO in flight, let it wait | |
1308 | */ | |
1309 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) | |
0b182d61 | 1310 | return false; |
2f5cb738 JA |
1311 | |
1312 | max_dispatch = cfqd->cfq_quantum; | |
1313 | if (cfq_class_idle(cfqq)) | |
1314 | max_dispatch = 1; | |
b4878f24 | 1315 | |
2f5cb738 JA |
1316 | /* |
1317 | * Does this cfqq already have too much IO in flight? | |
1318 | */ | |
1319 | if (cfqq->dispatched >= max_dispatch) { | |
1320 | /* | |
1321 | * idle queue must always only have a single IO in flight | |
1322 | */ | |
3ed9a296 | 1323 | if (cfq_class_idle(cfqq)) |
0b182d61 | 1324 | return false; |
3ed9a296 | 1325 | |
2f5cb738 JA |
1326 | /* |
1327 | * We have other queues, don't allow more IO from this one | |
1328 | */ | |
1329 | if (cfqd->busy_queues > 1) | |
0b182d61 | 1330 | return false; |
9ede209e | 1331 | |
365722bb | 1332 | /* |
8e296755 | 1333 | * Sole queue user, allow bigger slice |
365722bb | 1334 | */ |
8e296755 JA |
1335 | max_dispatch *= 4; |
1336 | } | |
1337 | ||
1338 | /* | |
1339 | * Async queues must wait a bit before being allowed dispatch. | |
1340 | * We also ramp up the dispatch depth gradually for async IO, | |
1341 | * based on the last sync IO we serviced | |
1342 | */ | |
963b72fc | 1343 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
8e296755 JA |
1344 | unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
1345 | unsigned int depth; | |
365722bb | 1346 | |
61f0c1dc | 1347 | depth = last_sync / cfqd->cfq_slice[1]; |
e00c54c3 JA |
1348 | if (!depth && !cfqq->dispatched) |
1349 | depth = 1; | |
8e296755 JA |
1350 | if (depth < max_dispatch) |
1351 | max_dispatch = depth; | |
2f5cb738 | 1352 | } |
3ed9a296 | 1353 | |
0b182d61 JA |
1354 | /* |
1355 | * If we're below the current max, allow a dispatch | |
1356 | */ | |
1357 | return cfqq->dispatched < max_dispatch; | |
1358 | } | |
1359 | ||
1360 | /* | |
1361 | * Dispatch a request from cfqq, moving them to the request queue | |
1362 | * dispatch list. | |
1363 | */ | |
1364 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1365 | { | |
1366 | struct request *rq; | |
1367 | ||
1368 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1369 | ||
1370 | if (!cfq_may_dispatch(cfqd, cfqq)) | |
1371 | return false; | |
1372 | ||
1373 | /* | |
1374 | * follow expired path, else get first next available | |
1375 | */ | |
1376 | rq = cfq_check_fifo(cfqq); | |
1377 | if (!rq) | |
1378 | rq = cfqq->next_rq; | |
1379 | ||
1380 | /* | |
1381 | * insert request into driver dispatch list | |
1382 | */ | |
1383 | cfq_dispatch_insert(cfqd->queue, rq); | |
1384 | ||
1385 | if (!cfqd->active_cic) { | |
1386 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1387 | ||
1388 | atomic_long_inc(&cic->ioc->refcount); | |
1389 | cfqd->active_cic = cic; | |
1390 | } | |
1391 | ||
1392 | return true; | |
1393 | } | |
1394 | ||
1395 | /* | |
1396 | * Find the cfqq that we need to service and move a request from that to the | |
1397 | * dispatch list | |
1398 | */ | |
1399 | static int cfq_dispatch_requests(struct request_queue *q, int force) | |
1400 | { | |
1401 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1402 | struct cfq_queue *cfqq; | |
1403 | ||
1404 | if (!cfqd->busy_queues) | |
1405 | return 0; | |
1406 | ||
1407 | if (unlikely(force)) | |
1408 | return cfq_forced_dispatch(cfqd); | |
1409 | ||
1410 | cfqq = cfq_select_queue(cfqd); | |
1411 | if (!cfqq) | |
8e296755 JA |
1412 | return 0; |
1413 | ||
2f5cb738 | 1414 | /* |
0b182d61 | 1415 | * Dispatch a request from this cfqq, if it is allowed |
2f5cb738 | 1416 | */ |
0b182d61 JA |
1417 | if (!cfq_dispatch_request(cfqd, cfqq)) |
1418 | return 0; | |
1419 | ||
2f5cb738 | 1420 | cfqq->slice_dispatch++; |
b029195d | 1421 | cfq_clear_cfqq_must_dispatch(cfqq); |
22e2c507 | 1422 | |
2f5cb738 JA |
1423 | /* |
1424 | * expire an async queue immediately if it has used up its slice. idle | |
1425 | * queue always expire after 1 dispatch round. | |
1426 | */ | |
1427 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
1428 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1429 | cfq_class_idle(cfqq))) { | |
1430 | cfqq->slice_end = jiffies + 1; | |
1431 | cfq_slice_expired(cfqd, 0); | |
1da177e4 LT |
1432 | } |
1433 | ||
b217a903 | 1434 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
2f5cb738 | 1435 | return 1; |
1da177e4 LT |
1436 | } |
1437 | ||
1da177e4 | 1438 | /* |
5e705374 JA |
1439 | * task holds one reference to the queue, dropped when task exits. each rq |
1440 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1441 | * |
1442 | * queue lock must be held here. | |
1443 | */ | |
1444 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1445 | { | |
22e2c507 JA |
1446 | struct cfq_data *cfqd = cfqq->cfqd; |
1447 | ||
1448 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1449 | |
1450 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1451 | return; | |
1452 | ||
7b679138 | 1453 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
1da177e4 | 1454 | BUG_ON(rb_first(&cfqq->sort_list)); |
22e2c507 | 1455 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1456 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1457 | |
28f95cbc | 1458 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1459 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1460 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1461 | } |
22e2c507 | 1462 | |
1da177e4 LT |
1463 | kmem_cache_free(cfq_pool, cfqq); |
1464 | } | |
1465 | ||
d6de8be7 JA |
1466 | /* |
1467 | * Must always be called with the rcu_read_lock() held | |
1468 | */ | |
07416d29 JA |
1469 | static void |
1470 | __call_for_each_cic(struct io_context *ioc, | |
1471 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1472 | { | |
1473 | struct cfq_io_context *cic; | |
1474 | struct hlist_node *n; | |
1475 | ||
1476 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
1477 | func(ioc, cic); | |
1478 | } | |
1479 | ||
4ac845a2 | 1480 | /* |
34e6bbf2 | 1481 | * Call func for each cic attached to this ioc. |
4ac845a2 | 1482 | */ |
34e6bbf2 | 1483 | static void |
4ac845a2 JA |
1484 | call_for_each_cic(struct io_context *ioc, |
1485 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1486 | { |
4ac845a2 | 1487 | rcu_read_lock(); |
07416d29 | 1488 | __call_for_each_cic(ioc, func); |
4ac845a2 | 1489 | rcu_read_unlock(); |
34e6bbf2 FC |
1490 | } |
1491 | ||
1492 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
1493 | { | |
1494 | struct cfq_io_context *cic; | |
1495 | ||
1496 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
1497 | ||
1498 | kmem_cache_free(cfq_ioc_pool, cic); | |
245b2e70 | 1499 | elv_ioc_count_dec(cfq_ioc_count); |
34e6bbf2 | 1500 | |
9a11b4ed JA |
1501 | if (ioc_gone) { |
1502 | /* | |
1503 | * CFQ scheduler is exiting, grab exit lock and check | |
1504 | * the pending io context count. If it hits zero, | |
1505 | * complete ioc_gone and set it back to NULL | |
1506 | */ | |
1507 | spin_lock(&ioc_gone_lock); | |
245b2e70 | 1508 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
9a11b4ed JA |
1509 | complete(ioc_gone); |
1510 | ioc_gone = NULL; | |
1511 | } | |
1512 | spin_unlock(&ioc_gone_lock); | |
1513 | } | |
34e6bbf2 | 1514 | } |
4ac845a2 | 1515 | |
34e6bbf2 FC |
1516 | static void cfq_cic_free(struct cfq_io_context *cic) |
1517 | { | |
1518 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
4ac845a2 JA |
1519 | } |
1520 | ||
1521 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1522 | { | |
1523 | unsigned long flags; | |
1524 | ||
1525 | BUG_ON(!cic->dead_key); | |
1526 | ||
1527 | spin_lock_irqsave(&ioc->lock, flags); | |
1528 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
ffc4e759 | 1529 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1530 | spin_unlock_irqrestore(&ioc->lock, flags); |
1531 | ||
34e6bbf2 | 1532 | cfq_cic_free(cic); |
4ac845a2 JA |
1533 | } |
1534 | ||
d6de8be7 JA |
1535 | /* |
1536 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
1537 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
1538 | * and ->trim() which is called with the task lock held | |
1539 | */ | |
4ac845a2 JA |
1540 | static void cfq_free_io_context(struct io_context *ioc) |
1541 | { | |
4ac845a2 | 1542 | /* |
34e6bbf2 FC |
1543 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
1544 | * so no more cic's are allowed to be linked into this ioc. So it | |
1545 | * should be ok to iterate over the known list, we will see all cic's | |
1546 | * since no new ones are added. | |
4ac845a2 | 1547 | */ |
07416d29 | 1548 | __call_for_each_cic(ioc, cic_free_func); |
1da177e4 LT |
1549 | } |
1550 | ||
89850f7e | 1551 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1552 | { |
df5fe3e8 JM |
1553 | struct cfq_queue *__cfqq, *next; |
1554 | ||
28f95cbc | 1555 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1556 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1557 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1558 | } |
22e2c507 | 1559 | |
df5fe3e8 JM |
1560 | /* |
1561 | * If this queue was scheduled to merge with another queue, be | |
1562 | * sure to drop the reference taken on that queue (and others in | |
1563 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. | |
1564 | */ | |
1565 | __cfqq = cfqq->new_cfqq; | |
1566 | while (__cfqq) { | |
1567 | if (__cfqq == cfqq) { | |
1568 | WARN(1, "cfqq->new_cfqq loop detected\n"); | |
1569 | break; | |
1570 | } | |
1571 | next = __cfqq->new_cfqq; | |
1572 | cfq_put_queue(__cfqq); | |
1573 | __cfqq = next; | |
1574 | } | |
1575 | ||
89850f7e JA |
1576 | cfq_put_queue(cfqq); |
1577 | } | |
22e2c507 | 1578 | |
89850f7e JA |
1579 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1580 | struct cfq_io_context *cic) | |
1581 | { | |
4faa3c81 FC |
1582 | struct io_context *ioc = cic->ioc; |
1583 | ||
fc46379d | 1584 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1585 | |
1586 | /* | |
1587 | * Make sure key == NULL is seen for dead queues | |
1588 | */ | |
fc46379d | 1589 | smp_wmb(); |
4ac845a2 | 1590 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1591 | cic->key = NULL; |
1592 | ||
4faa3c81 FC |
1593 | if (ioc->ioc_data == cic) |
1594 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
1595 | ||
ff6657c6 JA |
1596 | if (cic->cfqq[BLK_RW_ASYNC]) { |
1597 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
1598 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
12a05732 AV |
1599 | } |
1600 | ||
ff6657c6 JA |
1601 | if (cic->cfqq[BLK_RW_SYNC]) { |
1602 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
1603 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
12a05732 | 1604 | } |
89850f7e JA |
1605 | } |
1606 | ||
4ac845a2 JA |
1607 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1608 | struct cfq_io_context *cic) | |
89850f7e JA |
1609 | { |
1610 | struct cfq_data *cfqd = cic->key; | |
1611 | ||
89850f7e | 1612 | if (cfqd) { |
165125e1 | 1613 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1614 | unsigned long flags; |
89850f7e | 1615 | |
4ac845a2 | 1616 | spin_lock_irqsave(q->queue_lock, flags); |
62c1fe9d JA |
1617 | |
1618 | /* | |
1619 | * Ensure we get a fresh copy of the ->key to prevent | |
1620 | * race between exiting task and queue | |
1621 | */ | |
1622 | smp_read_barrier_depends(); | |
1623 | if (cic->key) | |
1624 | __cfq_exit_single_io_context(cfqd, cic); | |
1625 | ||
4ac845a2 | 1626 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1627 | } |
1da177e4 LT |
1628 | } |
1629 | ||
498d3aa2 JA |
1630 | /* |
1631 | * The process that ioc belongs to has exited, we need to clean up | |
1632 | * and put the internal structures we have that belongs to that process. | |
1633 | */ | |
e2d74ac0 | 1634 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1635 | { |
4ac845a2 | 1636 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
1da177e4 LT |
1637 | } |
1638 | ||
22e2c507 | 1639 | static struct cfq_io_context * |
8267e268 | 1640 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1641 | { |
b5deef90 | 1642 | struct cfq_io_context *cic; |
1da177e4 | 1643 | |
94f6030c CL |
1644 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1645 | cfqd->queue->node); | |
1da177e4 | 1646 | if (cic) { |
22e2c507 | 1647 | cic->last_end_request = jiffies; |
553698f9 | 1648 | INIT_LIST_HEAD(&cic->queue_list); |
ffc4e759 | 1649 | INIT_HLIST_NODE(&cic->cic_list); |
22e2c507 JA |
1650 | cic->dtor = cfq_free_io_context; |
1651 | cic->exit = cfq_exit_io_context; | |
245b2e70 | 1652 | elv_ioc_count_inc(cfq_ioc_count); |
1da177e4 LT |
1653 | } |
1654 | ||
1655 | return cic; | |
1656 | } | |
1657 | ||
fd0928df | 1658 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1659 | { |
1660 | struct task_struct *tsk = current; | |
1661 | int ioprio_class; | |
1662 | ||
3b18152c | 1663 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1664 | return; |
1665 | ||
fd0928df | 1666 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 | 1667 | switch (ioprio_class) { |
fe094d98 JA |
1668 | default: |
1669 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1670 | case IOPRIO_CLASS_NONE: | |
1671 | /* | |
6d63c275 | 1672 | * no prio set, inherit CPU scheduling settings |
fe094d98 JA |
1673 | */ |
1674 | cfqq->ioprio = task_nice_ioprio(tsk); | |
6d63c275 | 1675 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
fe094d98 JA |
1676 | break; |
1677 | case IOPRIO_CLASS_RT: | |
1678 | cfqq->ioprio = task_ioprio(ioc); | |
1679 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1680 | break; | |
1681 | case IOPRIO_CLASS_BE: | |
1682 | cfqq->ioprio = task_ioprio(ioc); | |
1683 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1684 | break; | |
1685 | case IOPRIO_CLASS_IDLE: | |
1686 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1687 | cfqq->ioprio = 7; | |
1688 | cfq_clear_cfqq_idle_window(cfqq); | |
1689 | break; | |
22e2c507 JA |
1690 | } |
1691 | ||
1692 | /* | |
1693 | * keep track of original prio settings in case we have to temporarily | |
1694 | * elevate the priority of this queue | |
1695 | */ | |
1696 | cfqq->org_ioprio = cfqq->ioprio; | |
1697 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1698 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1699 | } |
1700 | ||
febffd61 | 1701 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 1702 | { |
478a82b0 AV |
1703 | struct cfq_data *cfqd = cic->key; |
1704 | struct cfq_queue *cfqq; | |
c1b707d2 | 1705 | unsigned long flags; |
35e6077c | 1706 | |
caaa5f9f JA |
1707 | if (unlikely(!cfqd)) |
1708 | return; | |
1709 | ||
c1b707d2 | 1710 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f | 1711 | |
ff6657c6 | 1712 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
caaa5f9f JA |
1713 | if (cfqq) { |
1714 | struct cfq_queue *new_cfqq; | |
ff6657c6 JA |
1715 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
1716 | GFP_ATOMIC); | |
caaa5f9f | 1717 | if (new_cfqq) { |
ff6657c6 | 1718 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
caaa5f9f JA |
1719 | cfq_put_queue(cfqq); |
1720 | } | |
22e2c507 | 1721 | } |
caaa5f9f | 1722 | |
ff6657c6 | 1723 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
caaa5f9f JA |
1724 | if (cfqq) |
1725 | cfq_mark_cfqq_prio_changed(cfqq); | |
1726 | ||
c1b707d2 | 1727 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
1728 | } |
1729 | ||
fc46379d | 1730 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 1731 | { |
4ac845a2 | 1732 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 1733 | ioc->ioprio_changed = 0; |
22e2c507 JA |
1734 | } |
1735 | ||
d5036d77 | 1736 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 1737 | pid_t pid, bool is_sync) |
d5036d77 JA |
1738 | { |
1739 | RB_CLEAR_NODE(&cfqq->rb_node); | |
1740 | RB_CLEAR_NODE(&cfqq->p_node); | |
1741 | INIT_LIST_HEAD(&cfqq->fifo); | |
1742 | ||
1743 | atomic_set(&cfqq->ref, 0); | |
1744 | cfqq->cfqd = cfqd; | |
1745 | ||
1746 | cfq_mark_cfqq_prio_changed(cfqq); | |
1747 | ||
1748 | if (is_sync) { | |
1749 | if (!cfq_class_idle(cfqq)) | |
1750 | cfq_mark_cfqq_idle_window(cfqq); | |
1751 | cfq_mark_cfqq_sync(cfqq); | |
1752 | } | |
1753 | cfqq->pid = pid; | |
1754 | } | |
1755 | ||
22e2c507 | 1756 | static struct cfq_queue * |
a6151c3a | 1757 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
fd0928df | 1758 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 1759 | { |
22e2c507 | 1760 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 1761 | struct cfq_io_context *cic; |
22e2c507 JA |
1762 | |
1763 | retry: | |
4ac845a2 | 1764 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
1765 | /* cic always exists here */ |
1766 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 | 1767 | |
6118b70b JA |
1768 | /* |
1769 | * Always try a new alloc if we fell back to the OOM cfqq | |
1770 | * originally, since it should just be a temporary situation. | |
1771 | */ | |
1772 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
1773 | cfqq = NULL; | |
22e2c507 JA |
1774 | if (new_cfqq) { |
1775 | cfqq = new_cfqq; | |
1776 | new_cfqq = NULL; | |
1777 | } else if (gfp_mask & __GFP_WAIT) { | |
1778 | spin_unlock_irq(cfqd->queue->queue_lock); | |
94f6030c | 1779 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
6118b70b | 1780 | gfp_mask | __GFP_ZERO, |
94f6030c | 1781 | cfqd->queue->node); |
22e2c507 | 1782 | spin_lock_irq(cfqd->queue->queue_lock); |
6118b70b JA |
1783 | if (new_cfqq) |
1784 | goto retry; | |
22e2c507 | 1785 | } else { |
94f6030c CL |
1786 | cfqq = kmem_cache_alloc_node(cfq_pool, |
1787 | gfp_mask | __GFP_ZERO, | |
1788 | cfqd->queue->node); | |
22e2c507 JA |
1789 | } |
1790 | ||
6118b70b JA |
1791 | if (cfqq) { |
1792 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); | |
1793 | cfq_init_prio_data(cfqq, ioc); | |
1794 | cfq_log_cfqq(cfqd, cfqq, "alloced"); | |
1795 | } else | |
1796 | cfqq = &cfqd->oom_cfqq; | |
22e2c507 JA |
1797 | } |
1798 | ||
1799 | if (new_cfqq) | |
1800 | kmem_cache_free(cfq_pool, new_cfqq); | |
1801 | ||
22e2c507 JA |
1802 | return cfqq; |
1803 | } | |
1804 | ||
c2dea2d1 VT |
1805 | static struct cfq_queue ** |
1806 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
1807 | { | |
fe094d98 | 1808 | switch (ioprio_class) { |
c2dea2d1 VT |
1809 | case IOPRIO_CLASS_RT: |
1810 | return &cfqd->async_cfqq[0][ioprio]; | |
1811 | case IOPRIO_CLASS_BE: | |
1812 | return &cfqd->async_cfqq[1][ioprio]; | |
1813 | case IOPRIO_CLASS_IDLE: | |
1814 | return &cfqd->async_idle_cfqq; | |
1815 | default: | |
1816 | BUG(); | |
1817 | } | |
1818 | } | |
1819 | ||
15c31be4 | 1820 | static struct cfq_queue * |
a6151c3a | 1821 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
15c31be4 JA |
1822 | gfp_t gfp_mask) |
1823 | { | |
fd0928df JA |
1824 | const int ioprio = task_ioprio(ioc); |
1825 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 1826 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
1827 | struct cfq_queue *cfqq = NULL; |
1828 | ||
c2dea2d1 VT |
1829 | if (!is_sync) { |
1830 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
1831 | cfqq = *async_cfqq; | |
1832 | } | |
1833 | ||
6118b70b | 1834 | if (!cfqq) |
fd0928df | 1835 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
15c31be4 JA |
1836 | |
1837 | /* | |
1838 | * pin the queue now that it's allocated, scheduler exit will prune it | |
1839 | */ | |
c2dea2d1 | 1840 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 1841 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 1842 | *async_cfqq = cfqq; |
15c31be4 JA |
1843 | } |
1844 | ||
1845 | atomic_inc(&cfqq->ref); | |
1846 | return cfqq; | |
1847 | } | |
1848 | ||
498d3aa2 JA |
1849 | /* |
1850 | * We drop cfq io contexts lazily, so we may find a dead one. | |
1851 | */ | |
dbecf3ab | 1852 | static void |
4ac845a2 JA |
1853 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
1854 | struct cfq_io_context *cic) | |
dbecf3ab | 1855 | { |
4ac845a2 JA |
1856 | unsigned long flags; |
1857 | ||
fc46379d | 1858 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 1859 | |
4ac845a2 JA |
1860 | spin_lock_irqsave(&ioc->lock, flags); |
1861 | ||
4faa3c81 | 1862 | BUG_ON(ioc->ioc_data == cic); |
597bc485 | 1863 | |
4ac845a2 | 1864 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
ffc4e759 | 1865 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1866 | spin_unlock_irqrestore(&ioc->lock, flags); |
1867 | ||
1868 | cfq_cic_free(cic); | |
dbecf3ab OH |
1869 | } |
1870 | ||
e2d74ac0 | 1871 | static struct cfq_io_context * |
4ac845a2 | 1872 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 1873 | { |
e2d74ac0 | 1874 | struct cfq_io_context *cic; |
d6de8be7 | 1875 | unsigned long flags; |
4ac845a2 | 1876 | void *k; |
e2d74ac0 | 1877 | |
91fac317 VT |
1878 | if (unlikely(!ioc)) |
1879 | return NULL; | |
1880 | ||
d6de8be7 JA |
1881 | rcu_read_lock(); |
1882 | ||
597bc485 JA |
1883 | /* |
1884 | * we maintain a last-hit cache, to avoid browsing over the tree | |
1885 | */ | |
4ac845a2 | 1886 | cic = rcu_dereference(ioc->ioc_data); |
d6de8be7 JA |
1887 | if (cic && cic->key == cfqd) { |
1888 | rcu_read_unlock(); | |
597bc485 | 1889 | return cic; |
d6de8be7 | 1890 | } |
597bc485 | 1891 | |
4ac845a2 | 1892 | do { |
4ac845a2 JA |
1893 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
1894 | rcu_read_unlock(); | |
1895 | if (!cic) | |
1896 | break; | |
be3b0753 OH |
1897 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1898 | k = cic->key; | |
1899 | if (unlikely(!k)) { | |
4ac845a2 | 1900 | cfq_drop_dead_cic(cfqd, ioc, cic); |
d6de8be7 | 1901 | rcu_read_lock(); |
4ac845a2 | 1902 | continue; |
dbecf3ab | 1903 | } |
e2d74ac0 | 1904 | |
d6de8be7 | 1905 | spin_lock_irqsave(&ioc->lock, flags); |
4ac845a2 | 1906 | rcu_assign_pointer(ioc->ioc_data, cic); |
d6de8be7 | 1907 | spin_unlock_irqrestore(&ioc->lock, flags); |
4ac845a2 JA |
1908 | break; |
1909 | } while (1); | |
e2d74ac0 | 1910 | |
4ac845a2 | 1911 | return cic; |
e2d74ac0 JA |
1912 | } |
1913 | ||
4ac845a2 JA |
1914 | /* |
1915 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
1916 | * the process specific cfq io context when entered from the block layer. | |
1917 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
1918 | */ | |
febffd61 JA |
1919 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
1920 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 1921 | { |
0261d688 | 1922 | unsigned long flags; |
4ac845a2 | 1923 | int ret; |
e2d74ac0 | 1924 | |
4ac845a2 JA |
1925 | ret = radix_tree_preload(gfp_mask); |
1926 | if (!ret) { | |
1927 | cic->ioc = ioc; | |
1928 | cic->key = cfqd; | |
e2d74ac0 | 1929 | |
4ac845a2 JA |
1930 | spin_lock_irqsave(&ioc->lock, flags); |
1931 | ret = radix_tree_insert(&ioc->radix_root, | |
1932 | (unsigned long) cfqd, cic); | |
ffc4e759 JA |
1933 | if (!ret) |
1934 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
4ac845a2 | 1935 | spin_unlock_irqrestore(&ioc->lock, flags); |
e2d74ac0 | 1936 | |
4ac845a2 JA |
1937 | radix_tree_preload_end(); |
1938 | ||
1939 | if (!ret) { | |
1940 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1941 | list_add(&cic->queue_list, &cfqd->cic_list); | |
1942 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1943 | } | |
e2d74ac0 JA |
1944 | } |
1945 | ||
4ac845a2 JA |
1946 | if (ret) |
1947 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 1948 | |
4ac845a2 | 1949 | return ret; |
e2d74ac0 JA |
1950 | } |
1951 | ||
1da177e4 LT |
1952 | /* |
1953 | * Setup general io context and cfq io context. There can be several cfq | |
1954 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1955 | * than one device managed by cfq. |
1da177e4 LT |
1956 | */ |
1957 | static struct cfq_io_context * | |
e2d74ac0 | 1958 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1959 | { |
22e2c507 | 1960 | struct io_context *ioc = NULL; |
1da177e4 | 1961 | struct cfq_io_context *cic; |
1da177e4 | 1962 | |
22e2c507 | 1963 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1964 | |
b5deef90 | 1965 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
1966 | if (!ioc) |
1967 | return NULL; | |
1968 | ||
4ac845a2 | 1969 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
1970 | if (cic) |
1971 | goto out; | |
1da177e4 | 1972 | |
e2d74ac0 JA |
1973 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1974 | if (cic == NULL) | |
1975 | goto err; | |
1da177e4 | 1976 | |
4ac845a2 JA |
1977 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
1978 | goto err_free; | |
1979 | ||
1da177e4 | 1980 | out: |
fc46379d JA |
1981 | smp_read_barrier_depends(); |
1982 | if (unlikely(ioc->ioprio_changed)) | |
1983 | cfq_ioc_set_ioprio(ioc); | |
1984 | ||
1da177e4 | 1985 | return cic; |
4ac845a2 JA |
1986 | err_free: |
1987 | cfq_cic_free(cic); | |
1da177e4 LT |
1988 | err: |
1989 | put_io_context(ioc); | |
1990 | return NULL; | |
1991 | } | |
1992 | ||
22e2c507 JA |
1993 | static void |
1994 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1995 | { |
aaf1228d JA |
1996 | unsigned long elapsed = jiffies - cic->last_end_request; |
1997 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 1998 | |
22e2c507 JA |
1999 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
2000 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
2001 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
2002 | } | |
1da177e4 | 2003 | |
206dc69b | 2004 | static void |
b2c18e1e | 2005 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
6d048f53 | 2006 | struct request *rq) |
206dc69b JA |
2007 | { |
2008 | sector_t sdist; | |
2009 | u64 total; | |
2010 | ||
b2c18e1e | 2011 | if (!cfqq->last_request_pos) |
4d00aa47 | 2012 | sdist = 0; |
b2c18e1e JM |
2013 | else if (cfqq->last_request_pos < blk_rq_pos(rq)) |
2014 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; | |
206dc69b | 2015 | else |
b2c18e1e | 2016 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
206dc69b JA |
2017 | |
2018 | /* | |
2019 | * Don't allow the seek distance to get too large from the | |
2020 | * odd fragment, pagein, etc | |
2021 | */ | |
b2c18e1e JM |
2022 | if (cfqq->seek_samples <= 60) /* second&third seek */ |
2023 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024); | |
206dc69b | 2024 | else |
b2c18e1e | 2025 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64); |
206dc69b | 2026 | |
b2c18e1e JM |
2027 | cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8; |
2028 | cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8; | |
2029 | total = cfqq->seek_total + (cfqq->seek_samples/2); | |
2030 | do_div(total, cfqq->seek_samples); | |
2031 | cfqq->seek_mean = (sector_t)total; | |
206dc69b | 2032 | } |
1da177e4 | 2033 | |
22e2c507 JA |
2034 | /* |
2035 | * Disable idle window if the process thinks too long or seeks so much that | |
2036 | * it doesn't matter | |
2037 | */ | |
2038 | static void | |
2039 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
2040 | struct cfq_io_context *cic) | |
2041 | { | |
7b679138 | 2042 | int old_idle, enable_idle; |
1be92f2f | 2043 | |
0871714e JA |
2044 | /* |
2045 | * Don't idle for async or idle io prio class | |
2046 | */ | |
2047 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
2048 | return; |
2049 | ||
c265a7f4 | 2050 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 2051 | |
66dac98e | 2052 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
b2c18e1e | 2053 | (!cfqd->cfq_latency && cfqd->hw_tag && CFQQ_SEEKY(cfqq))) |
22e2c507 JA |
2054 | enable_idle = 0; |
2055 | else if (sample_valid(cic->ttime_samples)) { | |
ec60e4f6 | 2056 | unsigned int slice_idle = cfqd->cfq_slice_idle; |
b2c18e1e | 2057 | if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)) |
ec60e4f6 CZ |
2058 | slice_idle = msecs_to_jiffies(CFQ_MIN_TT); |
2059 | if (cic->ttime_mean > slice_idle) | |
22e2c507 JA |
2060 | enable_idle = 0; |
2061 | else | |
2062 | enable_idle = 1; | |
1da177e4 LT |
2063 | } |
2064 | ||
7b679138 JA |
2065 | if (old_idle != enable_idle) { |
2066 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
2067 | if (enable_idle) | |
2068 | cfq_mark_cfqq_idle_window(cfqq); | |
2069 | else | |
2070 | cfq_clear_cfqq_idle_window(cfqq); | |
2071 | } | |
22e2c507 | 2072 | } |
1da177e4 | 2073 | |
22e2c507 JA |
2074 | /* |
2075 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
2076 | * no or if we aren't sure, a 1 will cause a preempt. | |
2077 | */ | |
a6151c3a | 2078 | static bool |
22e2c507 | 2079 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
5e705374 | 2080 | struct request *rq) |
22e2c507 | 2081 | { |
6d048f53 | 2082 | struct cfq_queue *cfqq; |
22e2c507 | 2083 | |
6d048f53 JA |
2084 | cfqq = cfqd->active_queue; |
2085 | if (!cfqq) | |
a6151c3a | 2086 | return false; |
22e2c507 | 2087 | |
6d048f53 | 2088 | if (cfq_slice_used(cfqq)) |
a6151c3a | 2089 | return true; |
6d048f53 JA |
2090 | |
2091 | if (cfq_class_idle(new_cfqq)) | |
a6151c3a | 2092 | return false; |
22e2c507 JA |
2093 | |
2094 | if (cfq_class_idle(cfqq)) | |
a6151c3a | 2095 | return true; |
1e3335de | 2096 | |
374f84ac JA |
2097 | /* |
2098 | * if the new request is sync, but the currently running queue is | |
2099 | * not, let the sync request have priority. | |
2100 | */ | |
5e705374 | 2101 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
a6151c3a | 2102 | return true; |
1e3335de | 2103 | |
374f84ac JA |
2104 | /* |
2105 | * So both queues are sync. Let the new request get disk time if | |
2106 | * it's a metadata request and the current queue is doing regular IO. | |
2107 | */ | |
2108 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
a6151c3a | 2109 | return false; |
22e2c507 | 2110 | |
3a9a3f6c DS |
2111 | /* |
2112 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
2113 | */ | |
2114 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
a6151c3a | 2115 | return true; |
3a9a3f6c | 2116 | |
1e3335de | 2117 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
a6151c3a | 2118 | return false; |
1e3335de JA |
2119 | |
2120 | /* | |
2121 | * if this request is as-good as one we would expect from the | |
2122 | * current cfqq, let it preempt | |
2123 | */ | |
b2c18e1e | 2124 | if (cfq_rq_close(cfqd, cfqq, rq)) |
a6151c3a | 2125 | return true; |
1e3335de | 2126 | |
a6151c3a | 2127 | return false; |
22e2c507 JA |
2128 | } |
2129 | ||
2130 | /* | |
2131 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
2132 | * let it have half of its nominal slice. | |
2133 | */ | |
2134 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2135 | { | |
7b679138 | 2136 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
6084cdda | 2137 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 2138 | |
bf572256 JA |
2139 | /* |
2140 | * Put the new queue at the front of the of the current list, | |
2141 | * so we know that it will be selected next. | |
2142 | */ | |
2143 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
2144 | |
2145 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 2146 | |
44f7c160 JA |
2147 | cfqq->slice_end = 0; |
2148 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
2149 | } |
2150 | ||
22e2c507 | 2151 | /* |
5e705374 | 2152 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
2153 | * something we should do about it |
2154 | */ | |
2155 | static void | |
5e705374 JA |
2156 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2157 | struct request *rq) | |
22e2c507 | 2158 | { |
5e705374 | 2159 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 2160 | |
45333d5a | 2161 | cfqd->rq_queued++; |
374f84ac JA |
2162 | if (rq_is_meta(rq)) |
2163 | cfqq->meta_pending++; | |
2164 | ||
9c2c38a1 | 2165 | cfq_update_io_thinktime(cfqd, cic); |
b2c18e1e | 2166 | cfq_update_io_seektime(cfqd, cfqq, rq); |
9c2c38a1 JA |
2167 | cfq_update_idle_window(cfqd, cfqq, cic); |
2168 | ||
b2c18e1e | 2169 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
22e2c507 JA |
2170 | |
2171 | if (cfqq == cfqd->active_queue) { | |
2172 | /* | |
b029195d JA |
2173 | * Remember that we saw a request from this process, but |
2174 | * don't start queuing just yet. Otherwise we risk seeing lots | |
2175 | * of tiny requests, because we disrupt the normal plugging | |
d6ceb25e JA |
2176 | * and merging. If the request is already larger than a single |
2177 | * page, let it rip immediately. For that case we assume that | |
2d870722 JA |
2178 | * merging is already done. Ditto for a busy system that |
2179 | * has other work pending, don't risk delaying until the | |
2180 | * idle timer unplug to continue working. | |
22e2c507 | 2181 | */ |
d6ceb25e | 2182 | if (cfq_cfqq_wait_request(cfqq)) { |
2d870722 JA |
2183 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
2184 | cfqd->busy_queues > 1) { | |
d6ceb25e | 2185 | del_timer(&cfqd->idle_slice_timer); |
a7f55792 | 2186 | __blk_run_queue(cfqd->queue); |
d6ceb25e | 2187 | } |
b029195d | 2188 | cfq_mark_cfqq_must_dispatch(cfqq); |
d6ceb25e | 2189 | } |
5e705374 | 2190 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
2191 | /* |
2192 | * not the active queue - expire current slice if it is | |
2193 | * idle and has expired it's mean thinktime or this new queue | |
3a9a3f6c DS |
2194 | * has some old slice time left and is of higher priority or |
2195 | * this new queue is RT and the current one is BE | |
22e2c507 JA |
2196 | */ |
2197 | cfq_preempt_queue(cfqd, cfqq); | |
a7f55792 | 2198 | __blk_run_queue(cfqd->queue); |
22e2c507 | 2199 | } |
1da177e4 LT |
2200 | } |
2201 | ||
165125e1 | 2202 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2203 | { |
b4878f24 | 2204 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 2205 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 2206 | |
7b679138 | 2207 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
fd0928df | 2208 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 2209 | |
5e705374 | 2210 | cfq_add_rq_rb(rq); |
1da177e4 | 2211 | |
30996f40 | 2212 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
22e2c507 JA |
2213 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
2214 | ||
5e705374 | 2215 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
2216 | } |
2217 | ||
45333d5a AC |
2218 | /* |
2219 | * Update hw_tag based on peak queue depth over 50 samples under | |
2220 | * sufficient load. | |
2221 | */ | |
2222 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
2223 | { | |
5ad531db JA |
2224 | if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak) |
2225 | cfqd->rq_in_driver_peak = rq_in_driver(cfqd); | |
45333d5a AC |
2226 | |
2227 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
5ad531db | 2228 | rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2229 | return; |
2230 | ||
2231 | if (cfqd->hw_tag_samples++ < 50) | |
2232 | return; | |
2233 | ||
2234 | if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN) | |
2235 | cfqd->hw_tag = 1; | |
2236 | else | |
2237 | cfqd->hw_tag = 0; | |
2238 | ||
2239 | cfqd->hw_tag_samples = 0; | |
2240 | cfqd->rq_in_driver_peak = 0; | |
2241 | } | |
2242 | ||
165125e1 | 2243 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2244 | { |
5e705374 | 2245 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 2246 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 2247 | const int sync = rq_is_sync(rq); |
b4878f24 | 2248 | unsigned long now; |
1da177e4 | 2249 | |
b4878f24 | 2250 | now = jiffies; |
7b679138 | 2251 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
1da177e4 | 2252 | |
45333d5a AC |
2253 | cfq_update_hw_tag(cfqd); |
2254 | ||
5ad531db | 2255 | WARN_ON(!cfqd->rq_in_driver[sync]); |
6d048f53 | 2256 | WARN_ON(!cfqq->dispatched); |
5ad531db | 2257 | cfqd->rq_in_driver[sync]--; |
6d048f53 | 2258 | cfqq->dispatched--; |
1da177e4 | 2259 | |
3ed9a296 JA |
2260 | if (cfq_cfqq_sync(cfqq)) |
2261 | cfqd->sync_flight--; | |
2262 | ||
365722bb | 2263 | if (sync) { |
5e705374 | 2264 | RQ_CIC(rq)->last_end_request = now; |
365722bb VG |
2265 | cfqd->last_end_sync_rq = now; |
2266 | } | |
caaa5f9f JA |
2267 | |
2268 | /* | |
2269 | * If this is the active queue, check if it needs to be expired, | |
2270 | * or if we want to idle in case it has no pending requests. | |
2271 | */ | |
2272 | if (cfqd->active_queue == cfqq) { | |
a36e71f9 JA |
2273 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
2274 | ||
44f7c160 JA |
2275 | if (cfq_cfqq_slice_new(cfqq)) { |
2276 | cfq_set_prio_slice(cfqd, cfqq); | |
2277 | cfq_clear_cfqq_slice_new(cfqq); | |
2278 | } | |
a36e71f9 JA |
2279 | /* |
2280 | * If there are no requests waiting in this queue, and | |
2281 | * there are other queues ready to issue requests, AND | |
2282 | * those other queues are issuing requests within our | |
2283 | * mean seek distance, give them a chance to run instead | |
2284 | * of idling. | |
2285 | */ | |
0871714e | 2286 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 2287 | cfq_slice_expired(cfqd, 1); |
b3b6d040 | 2288 | else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq) && |
a36e71f9 | 2289 | sync && !rq_noidle(rq)) |
6d048f53 | 2290 | cfq_arm_slice_timer(cfqd); |
caaa5f9f | 2291 | } |
6d048f53 | 2292 | |
5ad531db | 2293 | if (!rq_in_driver(cfqd)) |
23e018a1 | 2294 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2295 | } |
2296 | ||
22e2c507 JA |
2297 | /* |
2298 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
2299 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
2300 | */ | |
2301 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 2302 | { |
22e2c507 JA |
2303 | if (has_fs_excl()) { |
2304 | /* | |
2305 | * boost idle prio on transactions that would lock out other | |
2306 | * users of the filesystem | |
2307 | */ | |
2308 | if (cfq_class_idle(cfqq)) | |
2309 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2310 | if (cfqq->ioprio > IOPRIO_NORM) | |
2311 | cfqq->ioprio = IOPRIO_NORM; | |
2312 | } else { | |
2313 | /* | |
2314 | * check if we need to unboost the queue | |
2315 | */ | |
2316 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
2317 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
2318 | if (cfqq->ioprio != cfqq->org_ioprio) | |
2319 | cfqq->ioprio = cfqq->org_ioprio; | |
2320 | } | |
22e2c507 | 2321 | } |
1da177e4 | 2322 | |
89850f7e | 2323 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 2324 | { |
1b379d8d | 2325 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 2326 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 2327 | return ELV_MQUEUE_MUST; |
3b18152c | 2328 | } |
1da177e4 | 2329 | |
22e2c507 | 2330 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
2331 | } |
2332 | ||
165125e1 | 2333 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
2334 | { |
2335 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2336 | struct task_struct *tsk = current; | |
91fac317 | 2337 | struct cfq_io_context *cic; |
22e2c507 JA |
2338 | struct cfq_queue *cfqq; |
2339 | ||
2340 | /* | |
2341 | * don't force setup of a queue from here, as a call to may_queue | |
2342 | * does not necessarily imply that a request actually will be queued. | |
2343 | * so just lookup a possibly existing queue, or return 'may queue' | |
2344 | * if that fails | |
2345 | */ | |
4ac845a2 | 2346 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
2347 | if (!cic) |
2348 | return ELV_MQUEUE_MAY; | |
2349 | ||
b0b78f81 | 2350 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
22e2c507 | 2351 | if (cfqq) { |
fd0928df | 2352 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
2353 | cfq_prio_boost(cfqq); |
2354 | ||
89850f7e | 2355 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
2356 | } |
2357 | ||
2358 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
2359 | } |
2360 | ||
1da177e4 LT |
2361 | /* |
2362 | * queue lock held here | |
2363 | */ | |
bb37b94c | 2364 | static void cfq_put_request(struct request *rq) |
1da177e4 | 2365 | { |
5e705374 | 2366 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 2367 | |
5e705374 | 2368 | if (cfqq) { |
22e2c507 | 2369 | const int rw = rq_data_dir(rq); |
1da177e4 | 2370 | |
22e2c507 JA |
2371 | BUG_ON(!cfqq->allocated[rw]); |
2372 | cfqq->allocated[rw]--; | |
1da177e4 | 2373 | |
5e705374 | 2374 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 2375 | |
1da177e4 | 2376 | rq->elevator_private = NULL; |
5e705374 | 2377 | rq->elevator_private2 = NULL; |
1da177e4 | 2378 | |
1da177e4 LT |
2379 | cfq_put_queue(cfqq); |
2380 | } | |
2381 | } | |
2382 | ||
df5fe3e8 JM |
2383 | static struct cfq_queue * |
2384 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
2385 | struct cfq_queue *cfqq) | |
2386 | { | |
2387 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); | |
2388 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); | |
b3b6d040 | 2389 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
df5fe3e8 JM |
2390 | cfq_put_queue(cfqq); |
2391 | return cic_to_cfqq(cic, 1); | |
2392 | } | |
2393 | ||
1da177e4 | 2394 | /* |
22e2c507 | 2395 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2396 | */ |
22e2c507 | 2397 | static int |
165125e1 | 2398 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
2399 | { |
2400 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2401 | struct cfq_io_context *cic; | |
2402 | const int rw = rq_data_dir(rq); | |
a6151c3a | 2403 | const bool is_sync = rq_is_sync(rq); |
22e2c507 | 2404 | struct cfq_queue *cfqq; |
1da177e4 LT |
2405 | unsigned long flags; |
2406 | ||
2407 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2408 | ||
e2d74ac0 | 2409 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2410 | |
1da177e4 LT |
2411 | spin_lock_irqsave(q->queue_lock, flags); |
2412 | ||
22e2c507 JA |
2413 | if (!cic) |
2414 | goto queue_fail; | |
2415 | ||
91fac317 | 2416 | cfqq = cic_to_cfqq(cic, is_sync); |
32f2e807 | 2417 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
fd0928df | 2418 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 2419 | cic_set_cfqq(cic, cfqq, is_sync); |
df5fe3e8 JM |
2420 | } else { |
2421 | /* | |
2422 | * Check to see if this queue is scheduled to merge with | |
2423 | * another, closely cooperating queue. The merging of | |
2424 | * queues happens here as it must be done in process context. | |
2425 | * The reference on new_cfqq was taken in merge_cfqqs. | |
2426 | */ | |
2427 | if (cfqq->new_cfqq) | |
2428 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); | |
91fac317 | 2429 | } |
1da177e4 LT |
2430 | |
2431 | cfqq->allocated[rw]++; | |
22e2c507 | 2432 | atomic_inc(&cfqq->ref); |
1da177e4 | 2433 | |
5e705374 | 2434 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 2435 | |
5e705374 JA |
2436 | rq->elevator_private = cic; |
2437 | rq->elevator_private2 = cfqq; | |
2438 | return 0; | |
1da177e4 | 2439 | |
22e2c507 JA |
2440 | queue_fail: |
2441 | if (cic) | |
2442 | put_io_context(cic->ioc); | |
89850f7e | 2443 | |
23e018a1 | 2444 | cfq_schedule_dispatch(cfqd); |
1da177e4 | 2445 | spin_unlock_irqrestore(q->queue_lock, flags); |
7b679138 | 2446 | cfq_log(cfqd, "set_request fail"); |
1da177e4 LT |
2447 | return 1; |
2448 | } | |
2449 | ||
65f27f38 | 2450 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 2451 | { |
65f27f38 | 2452 | struct cfq_data *cfqd = |
23e018a1 | 2453 | container_of(work, struct cfq_data, unplug_work); |
165125e1 | 2454 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2455 | |
40bb54d1 | 2456 | spin_lock_irq(q->queue_lock); |
a7f55792 | 2457 | __blk_run_queue(cfqd->queue); |
40bb54d1 | 2458 | spin_unlock_irq(q->queue_lock); |
22e2c507 JA |
2459 | } |
2460 | ||
2461 | /* | |
2462 | * Timer running if the active_queue is currently idling inside its time slice | |
2463 | */ | |
2464 | static void cfq_idle_slice_timer(unsigned long data) | |
2465 | { | |
2466 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2467 | struct cfq_queue *cfqq; | |
2468 | unsigned long flags; | |
3c6bd2f8 | 2469 | int timed_out = 1; |
22e2c507 | 2470 | |
7b679138 JA |
2471 | cfq_log(cfqd, "idle timer fired"); |
2472 | ||
22e2c507 JA |
2473 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2474 | ||
fe094d98 JA |
2475 | cfqq = cfqd->active_queue; |
2476 | if (cfqq) { | |
3c6bd2f8 JA |
2477 | timed_out = 0; |
2478 | ||
b029195d JA |
2479 | /* |
2480 | * We saw a request before the queue expired, let it through | |
2481 | */ | |
2482 | if (cfq_cfqq_must_dispatch(cfqq)) | |
2483 | goto out_kick; | |
2484 | ||
22e2c507 JA |
2485 | /* |
2486 | * expired | |
2487 | */ | |
44f7c160 | 2488 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2489 | goto expire; |
2490 | ||
2491 | /* | |
2492 | * only expire and reinvoke request handler, if there are | |
2493 | * other queues with pending requests | |
2494 | */ | |
caaa5f9f | 2495 | if (!cfqd->busy_queues) |
22e2c507 | 2496 | goto out_cont; |
22e2c507 JA |
2497 | |
2498 | /* | |
2499 | * not expired and it has a request pending, let it dispatch | |
2500 | */ | |
75e50984 | 2501 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 2502 | goto out_kick; |
22e2c507 JA |
2503 | } |
2504 | expire: | |
6084cdda | 2505 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2506 | out_kick: |
23e018a1 | 2507 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2508 | out_cont: |
2509 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2510 | } | |
2511 | ||
3b18152c JA |
2512 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2513 | { | |
2514 | del_timer_sync(&cfqd->idle_slice_timer); | |
23e018a1 | 2515 | cancel_work_sync(&cfqd->unplug_work); |
3b18152c | 2516 | } |
22e2c507 | 2517 | |
c2dea2d1 VT |
2518 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2519 | { | |
2520 | int i; | |
2521 | ||
2522 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2523 | if (cfqd->async_cfqq[0][i]) | |
2524 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2525 | if (cfqd->async_cfqq[1][i]) | |
2526 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
c2dea2d1 | 2527 | } |
2389d1ef ON |
2528 | |
2529 | if (cfqd->async_idle_cfqq) | |
2530 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2531 | } |
2532 | ||
b374d18a | 2533 | static void cfq_exit_queue(struct elevator_queue *e) |
1da177e4 | 2534 | { |
22e2c507 | 2535 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2536 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2537 | |
3b18152c | 2538 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2539 | |
d9ff4187 | 2540 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2541 | |
d9ff4187 | 2542 | if (cfqd->active_queue) |
6084cdda | 2543 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2544 | |
2545 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2546 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2547 | struct cfq_io_context, | |
2548 | queue_list); | |
89850f7e JA |
2549 | |
2550 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2551 | } |
e2d74ac0 | 2552 | |
c2dea2d1 | 2553 | cfq_put_async_queues(cfqd); |
15c31be4 | 2554 | |
d9ff4187 | 2555 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2556 | |
2557 | cfq_shutdown_timer_wq(cfqd); | |
2558 | ||
a90d742e | 2559 | kfree(cfqd); |
1da177e4 LT |
2560 | } |
2561 | ||
165125e1 | 2562 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2563 | { |
2564 | struct cfq_data *cfqd; | |
26a2ac00 | 2565 | int i; |
1da177e4 | 2566 | |
94f6030c | 2567 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2568 | if (!cfqd) |
bc1c1169 | 2569 | return NULL; |
1da177e4 | 2570 | |
cc09e299 | 2571 | cfqd->service_tree = CFQ_RB_ROOT; |
26a2ac00 JA |
2572 | |
2573 | /* | |
2574 | * Not strictly needed (since RB_ROOT just clears the node and we | |
2575 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
2576 | * to add magic to the rb code | |
2577 | */ | |
2578 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2579 | cfqd->prio_trees[i] = RB_ROOT; | |
2580 | ||
6118b70b JA |
2581 | /* |
2582 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. | |
2583 | * Grab a permanent reference to it, so that the normal code flow | |
2584 | * will not attempt to free it. | |
2585 | */ | |
2586 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); | |
2587 | atomic_inc(&cfqd->oom_cfqq.ref); | |
2588 | ||
d9ff4187 | 2589 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2590 | |
1da177e4 | 2591 | cfqd->queue = q; |
1da177e4 | 2592 | |
22e2c507 JA |
2593 | init_timer(&cfqd->idle_slice_timer); |
2594 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2595 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2596 | ||
23e018a1 | 2597 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2598 | |
1da177e4 | 2599 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2600 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2601 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2602 | cfqd->cfq_back_max = cfq_back_max; |
2603 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2604 | cfqd->cfq_slice[0] = cfq_slice_async; |
2605 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2606 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2607 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
963b72fc | 2608 | cfqd->cfq_latency = 1; |
45333d5a | 2609 | cfqd->hw_tag = 1; |
365722bb | 2610 | cfqd->last_end_sync_rq = jiffies; |
bc1c1169 | 2611 | return cfqd; |
1da177e4 LT |
2612 | } |
2613 | ||
2614 | static void cfq_slab_kill(void) | |
2615 | { | |
d6de8be7 JA |
2616 | /* |
2617 | * Caller already ensured that pending RCU callbacks are completed, | |
2618 | * so we should have no busy allocations at this point. | |
2619 | */ | |
1da177e4 LT |
2620 | if (cfq_pool) |
2621 | kmem_cache_destroy(cfq_pool); | |
2622 | if (cfq_ioc_pool) | |
2623 | kmem_cache_destroy(cfq_ioc_pool); | |
2624 | } | |
2625 | ||
2626 | static int __init cfq_slab_setup(void) | |
2627 | { | |
0a31bd5f | 2628 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
2629 | if (!cfq_pool) |
2630 | goto fail; | |
2631 | ||
34e6bbf2 | 2632 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
2633 | if (!cfq_ioc_pool) |
2634 | goto fail; | |
2635 | ||
2636 | return 0; | |
2637 | fail: | |
2638 | cfq_slab_kill(); | |
2639 | return -ENOMEM; | |
2640 | } | |
2641 | ||
1da177e4 LT |
2642 | /* |
2643 | * sysfs parts below --> | |
2644 | */ | |
1da177e4 LT |
2645 | static ssize_t |
2646 | cfq_var_show(unsigned int var, char *page) | |
2647 | { | |
2648 | return sprintf(page, "%d\n", var); | |
2649 | } | |
2650 | ||
2651 | static ssize_t | |
2652 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2653 | { | |
2654 | char *p = (char *) page; | |
2655 | ||
2656 | *var = simple_strtoul(p, &p, 10); | |
2657 | return count; | |
2658 | } | |
2659 | ||
1da177e4 | 2660 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
b374d18a | 2661 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
1da177e4 | 2662 | { \ |
3d1ab40f | 2663 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2664 | unsigned int __data = __VAR; \ |
2665 | if (__CONV) \ | |
2666 | __data = jiffies_to_msecs(__data); \ | |
2667 | return cfq_var_show(__data, (page)); \ | |
2668 | } | |
2669 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
2670 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2671 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2672 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2673 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2674 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2675 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2676 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2677 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
963b72fc | 2678 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
1da177e4 LT |
2679 | #undef SHOW_FUNCTION |
2680 | ||
2681 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
b374d18a | 2682 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
1da177e4 | 2683 | { \ |
3d1ab40f | 2684 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2685 | unsigned int __data; \ |
2686 | int ret = cfq_var_store(&__data, (page), count); \ | |
2687 | if (__data < (MIN)) \ | |
2688 | __data = (MIN); \ | |
2689 | else if (__data > (MAX)) \ | |
2690 | __data = (MAX); \ | |
2691 | if (__CONV) \ | |
2692 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2693 | else \ | |
2694 | *(__PTR) = __data; \ | |
2695 | return ret; \ | |
2696 | } | |
2697 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
fe094d98 JA |
2698 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
2699 | UINT_MAX, 1); | |
2700 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
2701 | UINT_MAX, 1); | |
e572ec7e | 2702 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
fe094d98 JA |
2703 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
2704 | UINT_MAX, 0); | |
22e2c507 JA |
2705 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2706 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2707 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
fe094d98 JA |
2708 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
2709 | UINT_MAX, 0); | |
963b72fc | 2710 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
1da177e4 LT |
2711 | #undef STORE_FUNCTION |
2712 | ||
e572ec7e AV |
2713 | #define CFQ_ATTR(name) \ |
2714 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2715 | ||
2716 | static struct elv_fs_entry cfq_attrs[] = { | |
2717 | CFQ_ATTR(quantum), | |
e572ec7e AV |
2718 | CFQ_ATTR(fifo_expire_sync), |
2719 | CFQ_ATTR(fifo_expire_async), | |
2720 | CFQ_ATTR(back_seek_max), | |
2721 | CFQ_ATTR(back_seek_penalty), | |
2722 | CFQ_ATTR(slice_sync), | |
2723 | CFQ_ATTR(slice_async), | |
2724 | CFQ_ATTR(slice_async_rq), | |
2725 | CFQ_ATTR(slice_idle), | |
963b72fc | 2726 | CFQ_ATTR(low_latency), |
e572ec7e | 2727 | __ATTR_NULL |
1da177e4 LT |
2728 | }; |
2729 | ||
1da177e4 LT |
2730 | static struct elevator_type iosched_cfq = { |
2731 | .ops = { | |
2732 | .elevator_merge_fn = cfq_merge, | |
2733 | .elevator_merged_fn = cfq_merged_request, | |
2734 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 2735 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 2736 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2737 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2738 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2739 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2740 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2741 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
2742 | .elevator_former_req_fn = elv_rb_former_request, |
2743 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
2744 | .elevator_set_req_fn = cfq_set_request, |
2745 | .elevator_put_req_fn = cfq_put_request, | |
2746 | .elevator_may_queue_fn = cfq_may_queue, | |
2747 | .elevator_init_fn = cfq_init_queue, | |
2748 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 2749 | .trim = cfq_free_io_context, |
1da177e4 | 2750 | }, |
3d1ab40f | 2751 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2752 | .elevator_name = "cfq", |
2753 | .elevator_owner = THIS_MODULE, | |
2754 | }; | |
2755 | ||
2756 | static int __init cfq_init(void) | |
2757 | { | |
22e2c507 JA |
2758 | /* |
2759 | * could be 0 on HZ < 1000 setups | |
2760 | */ | |
2761 | if (!cfq_slice_async) | |
2762 | cfq_slice_async = 1; | |
2763 | if (!cfq_slice_idle) | |
2764 | cfq_slice_idle = 1; | |
2765 | ||
1da177e4 LT |
2766 | if (cfq_slab_setup()) |
2767 | return -ENOMEM; | |
2768 | ||
2fdd82bd | 2769 | elv_register(&iosched_cfq); |
1da177e4 | 2770 | |
2fdd82bd | 2771 | return 0; |
1da177e4 LT |
2772 | } |
2773 | ||
2774 | static void __exit cfq_exit(void) | |
2775 | { | |
6e9a4738 | 2776 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 2777 | elv_unregister(&iosched_cfq); |
334e94de | 2778 | ioc_gone = &all_gone; |
fba82272 OH |
2779 | /* ioc_gone's update must be visible before reading ioc_count */ |
2780 | smp_wmb(); | |
d6de8be7 JA |
2781 | |
2782 | /* | |
2783 | * this also protects us from entering cfq_slab_kill() with | |
2784 | * pending RCU callbacks | |
2785 | */ | |
245b2e70 | 2786 | if (elv_ioc_count_read(cfq_ioc_count)) |
9a11b4ed | 2787 | wait_for_completion(&all_gone); |
83521d3e | 2788 | cfq_slab_kill(); |
1da177e4 LT |
2789 | } |
2790 | ||
2791 | module_init(cfq_init); | |
2792 | module_exit(cfq_exit); | |
2793 | ||
2794 | MODULE_AUTHOR("Jens Axboe"); | |
2795 | MODULE_LICENSE("GPL"); | |
2796 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |