Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * CFQ, or complete fairness queueing, disk scheduler. |
3 | * | |
4 | * Based on ideas from a previously unfinished io | |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
6 | * | |
0fe23479 | 7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
1da177e4 | 8 | */ |
1da177e4 | 9 | #include <linux/module.h> |
1cc9be68 AV |
10 | #include <linux/blkdev.h> |
11 | #include <linux/elevator.h> | |
1da177e4 | 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 | |
4050cf16 | 51 | static DEFINE_PER_CPU(unsigned long, 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 | ||
22e2c507 JA |
73 | /* |
74 | * Per block device queue structure | |
75 | */ | |
1da177e4 | 76 | struct cfq_data { |
165125e1 | 77 | struct request_queue *queue; |
22e2c507 JA |
78 | |
79 | /* | |
80 | * rr list of queues with requests and the count of them | |
81 | */ | |
cc09e299 | 82 | struct cfq_rb_root service_tree; |
a36e71f9 JA |
83 | |
84 | /* | |
85 | * Each priority tree is sorted by next_request position. These | |
86 | * trees are used when determining if two or more queues are | |
87 | * interleaving requests (see cfq_close_cooperator). | |
88 | */ | |
89 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
90 | ||
22e2c507 | 91 | unsigned int busy_queues; |
3a9a3f6c DS |
92 | /* |
93 | * Used to track any pending rt requests so we can pre-empt current | |
94 | * non-RT cfqq in service when this value is non-zero. | |
95 | */ | |
96 | unsigned int busy_rt_queues; | |
22e2c507 | 97 | |
22e2c507 | 98 | int rq_in_driver; |
3ed9a296 | 99 | int sync_flight; |
45333d5a AC |
100 | |
101 | /* | |
102 | * queue-depth detection | |
103 | */ | |
104 | int rq_queued; | |
25776e35 | 105 | int hw_tag; |
45333d5a AC |
106 | int hw_tag_samples; |
107 | int rq_in_driver_peak; | |
1da177e4 | 108 | |
22e2c507 JA |
109 | /* |
110 | * idle window management | |
111 | */ | |
112 | struct timer_list idle_slice_timer; | |
113 | struct work_struct unplug_work; | |
1da177e4 | 114 | |
22e2c507 JA |
115 | struct cfq_queue *active_queue; |
116 | struct cfq_io_context *active_cic; | |
22e2c507 | 117 | |
c2dea2d1 VT |
118 | /* |
119 | * async queue for each priority case | |
120 | */ | |
121 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
122 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 123 | |
6d048f53 | 124 | sector_t last_position; |
1da177e4 | 125 | |
1da177e4 LT |
126 | /* |
127 | * tunables, see top of file | |
128 | */ | |
129 | unsigned int cfq_quantum; | |
22e2c507 | 130 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
131 | unsigned int cfq_back_penalty; |
132 | unsigned int cfq_back_max; | |
22e2c507 JA |
133 | unsigned int cfq_slice[2]; |
134 | unsigned int cfq_slice_async_rq; | |
135 | unsigned int cfq_slice_idle; | |
d9ff4187 AV |
136 | |
137 | struct list_head cic_list; | |
1da177e4 LT |
138 | }; |
139 | ||
22e2c507 JA |
140 | /* |
141 | * Per process-grouping structure | |
142 | */ | |
1da177e4 LT |
143 | struct cfq_queue { |
144 | /* reference count */ | |
145 | atomic_t ref; | |
be754d2c RK |
146 | /* various state flags, see below */ |
147 | unsigned int flags; | |
1da177e4 LT |
148 | /* parent cfq_data */ |
149 | struct cfq_data *cfqd; | |
d9e7620e JA |
150 | /* service_tree member */ |
151 | struct rb_node rb_node; | |
152 | /* service_tree key */ | |
153 | unsigned long rb_key; | |
a36e71f9 JA |
154 | /* prio tree member */ |
155 | struct rb_node p_node; | |
f2d1f0ae JA |
156 | /* prio tree root we belong to, if any */ |
157 | struct rb_root *p_root; | |
1da177e4 LT |
158 | /* sorted list of pending requests */ |
159 | struct rb_root sort_list; | |
160 | /* if fifo isn't expired, next request to serve */ | |
5e705374 | 161 | struct request *next_rq; |
1da177e4 LT |
162 | /* requests queued in sort_list */ |
163 | int queued[2]; | |
164 | /* currently allocated requests */ | |
165 | int allocated[2]; | |
166 | /* fifo list of requests in sort_list */ | |
22e2c507 | 167 | struct list_head fifo; |
1da177e4 | 168 | |
22e2c507 | 169 | unsigned long slice_end; |
c5b680f3 | 170 | long slice_resid; |
2f5cb738 | 171 | unsigned int slice_dispatch; |
1da177e4 | 172 | |
be754d2c RK |
173 | /* pending metadata requests */ |
174 | int meta_pending; | |
6d048f53 JA |
175 | /* number of requests that are on the dispatch list or inside driver */ |
176 | int dispatched; | |
22e2c507 JA |
177 | |
178 | /* io prio of this group */ | |
179 | unsigned short ioprio, org_ioprio; | |
180 | unsigned short ioprio_class, org_ioprio_class; | |
181 | ||
7b679138 | 182 | pid_t pid; |
1da177e4 LT |
183 | }; |
184 | ||
3b18152c | 185 | enum cfqq_state_flags { |
b0b8d749 JA |
186 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
187 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
b029195d | 188 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
b0b8d749 JA |
189 | CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ |
190 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ | |
b0b8d749 JA |
191 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
192 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
193 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
44f7c160 | 194 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 195 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
a36e71f9 | 196 | CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */ |
3b18152c JA |
197 | }; |
198 | ||
199 | #define CFQ_CFQQ_FNS(name) \ | |
200 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
201 | { \ | |
fe094d98 | 202 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
203 | } \ |
204 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
205 | { \ | |
fe094d98 | 206 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
207 | } \ |
208 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
209 | { \ | |
fe094d98 | 210 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
3b18152c JA |
211 | } |
212 | ||
213 | CFQ_CFQQ_FNS(on_rr); | |
214 | CFQ_CFQQ_FNS(wait_request); | |
b029195d | 215 | CFQ_CFQQ_FNS(must_dispatch); |
3b18152c JA |
216 | CFQ_CFQQ_FNS(must_alloc); |
217 | CFQ_CFQQ_FNS(must_alloc_slice); | |
3b18152c JA |
218 | CFQ_CFQQ_FNS(fifo_expire); |
219 | CFQ_CFQQ_FNS(idle_window); | |
220 | CFQ_CFQQ_FNS(prio_changed); | |
44f7c160 | 221 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 222 | CFQ_CFQQ_FNS(sync); |
a36e71f9 | 223 | CFQ_CFQQ_FNS(coop); |
3b18152c JA |
224 | #undef CFQ_CFQQ_FNS |
225 | ||
7b679138 JA |
226 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
227 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
228 | #define cfq_log(cfqd, fmt, args...) \ | |
229 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
230 | ||
165125e1 | 231 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
91fac317 | 232 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, int, |
fd0928df | 233 | struct io_context *, gfp_t); |
4ac845a2 | 234 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
235 | struct io_context *); |
236 | ||
237 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, | |
238 | int is_sync) | |
239 | { | |
240 | return cic->cfqq[!!is_sync]; | |
241 | } | |
242 | ||
243 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
244 | struct cfq_queue *cfqq, int is_sync) | |
245 | { | |
246 | cic->cfqq[!!is_sync] = cfqq; | |
247 | } | |
248 | ||
249 | /* | |
250 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
251 | * set (in which case it could also be direct WRITE). | |
252 | */ | |
253 | static inline int cfq_bio_sync(struct bio *bio) | |
254 | { | |
255 | if (bio_data_dir(bio) == READ || bio_sync(bio)) | |
256 | return 1; | |
257 | ||
258 | return 0; | |
259 | } | |
1da177e4 | 260 | |
99f95e52 AM |
261 | /* |
262 | * scheduler run of queue, if there are requests pending and no one in the | |
263 | * driver that will restart queueing | |
264 | */ | |
265 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
266 | { | |
7b679138 JA |
267 | if (cfqd->busy_queues) { |
268 | cfq_log(cfqd, "schedule dispatch"); | |
18887ad9 | 269 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
7b679138 | 270 | } |
99f95e52 AM |
271 | } |
272 | ||
165125e1 | 273 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
274 | { |
275 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
276 | ||
b4878f24 | 277 | return !cfqd->busy_queues; |
99f95e52 AM |
278 | } |
279 | ||
44f7c160 JA |
280 | /* |
281 | * Scale schedule slice based on io priority. Use the sync time slice only | |
282 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
283 | * io only, should not get full sync slice length. | |
284 | */ | |
d9e7620e JA |
285 | static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync, |
286 | unsigned short prio) | |
44f7c160 | 287 | { |
d9e7620e | 288 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 289 | |
d9e7620e JA |
290 | WARN_ON(prio >= IOPRIO_BE_NR); |
291 | ||
292 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
293 | } | |
44f7c160 | 294 | |
d9e7620e JA |
295 | static inline int |
296 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
297 | { | |
298 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
299 | } |
300 | ||
301 | static inline void | |
302 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
303 | { | |
304 | cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; | |
7b679138 | 305 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
44f7c160 JA |
306 | } |
307 | ||
308 | /* | |
309 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
310 | * isn't valid until the first request from the dispatch is activated | |
311 | * and the slice time set. | |
312 | */ | |
313 | static inline int cfq_slice_used(struct cfq_queue *cfqq) | |
314 | { | |
315 | if (cfq_cfqq_slice_new(cfqq)) | |
316 | return 0; | |
317 | if (time_before(jiffies, cfqq->slice_end)) | |
318 | return 0; | |
319 | ||
320 | return 1; | |
321 | } | |
322 | ||
1da177e4 | 323 | /* |
5e705374 | 324 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 325 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 326 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 327 | */ |
5e705374 JA |
328 | static struct request * |
329 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) | |
1da177e4 LT |
330 | { |
331 | sector_t last, s1, s2, d1 = 0, d2 = 0; | |
1da177e4 | 332 | unsigned long back_max; |
e8a99053 AM |
333 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
334 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
335 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 336 | |
5e705374 JA |
337 | if (rq1 == NULL || rq1 == rq2) |
338 | return rq2; | |
339 | if (rq2 == NULL) | |
340 | return rq1; | |
9c2c38a1 | 341 | |
5e705374 JA |
342 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
343 | return rq1; | |
344 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
345 | return rq2; | |
374f84ac JA |
346 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
347 | return rq1; | |
348 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
349 | return rq2; | |
1da177e4 | 350 | |
83096ebf TH |
351 | s1 = blk_rq_pos(rq1); |
352 | s2 = blk_rq_pos(rq2); | |
1da177e4 | 353 | |
6d048f53 | 354 | last = cfqd->last_position; |
1da177e4 | 355 | |
1da177e4 LT |
356 | /* |
357 | * by definition, 1KiB is 2 sectors | |
358 | */ | |
359 | back_max = cfqd->cfq_back_max * 2; | |
360 | ||
361 | /* | |
362 | * Strict one way elevator _except_ in the case where we allow | |
363 | * short backward seeks which are biased as twice the cost of a | |
364 | * similar forward seek. | |
365 | */ | |
366 | if (s1 >= last) | |
367 | d1 = s1 - last; | |
368 | else if (s1 + back_max >= last) | |
369 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
370 | else | |
e8a99053 | 371 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
372 | |
373 | if (s2 >= last) | |
374 | d2 = s2 - last; | |
375 | else if (s2 + back_max >= last) | |
376 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
377 | else | |
e8a99053 | 378 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
379 | |
380 | /* Found required data */ | |
e8a99053 AM |
381 | |
382 | /* | |
383 | * By doing switch() on the bit mask "wrap" we avoid having to | |
384 | * check two variables for all permutations: --> faster! | |
385 | */ | |
386 | switch (wrap) { | |
5e705374 | 387 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 388 | if (d1 < d2) |
5e705374 | 389 | return rq1; |
e8a99053 | 390 | else if (d2 < d1) |
5e705374 | 391 | return rq2; |
e8a99053 AM |
392 | else { |
393 | if (s1 >= s2) | |
5e705374 | 394 | return rq1; |
e8a99053 | 395 | else |
5e705374 | 396 | return rq2; |
e8a99053 | 397 | } |
1da177e4 | 398 | |
e8a99053 | 399 | case CFQ_RQ2_WRAP: |
5e705374 | 400 | return rq1; |
e8a99053 | 401 | case CFQ_RQ1_WRAP: |
5e705374 JA |
402 | return rq2; |
403 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
404 | default: |
405 | /* | |
406 | * Since both rqs are wrapped, | |
407 | * start with the one that's further behind head | |
408 | * (--> only *one* back seek required), | |
409 | * since back seek takes more time than forward. | |
410 | */ | |
411 | if (s1 <= s2) | |
5e705374 | 412 | return rq1; |
1da177e4 | 413 | else |
5e705374 | 414 | return rq2; |
1da177e4 LT |
415 | } |
416 | } | |
417 | ||
498d3aa2 JA |
418 | /* |
419 | * The below is leftmost cache rbtree addon | |
420 | */ | |
0871714e | 421 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 JA |
422 | { |
423 | if (!root->left) | |
424 | root->left = rb_first(&root->rb); | |
425 | ||
0871714e JA |
426 | if (root->left) |
427 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
428 | ||
429 | return NULL; | |
cc09e299 JA |
430 | } |
431 | ||
a36e71f9 JA |
432 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
433 | { | |
434 | rb_erase(n, root); | |
435 | RB_CLEAR_NODE(n); | |
436 | } | |
437 | ||
cc09e299 JA |
438 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
439 | { | |
440 | if (root->left == n) | |
441 | root->left = NULL; | |
a36e71f9 | 442 | rb_erase_init(n, &root->rb); |
cc09e299 JA |
443 | } |
444 | ||
1da177e4 LT |
445 | /* |
446 | * would be nice to take fifo expire time into account as well | |
447 | */ | |
5e705374 JA |
448 | static struct request * |
449 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
450 | struct request *last) | |
1da177e4 | 451 | { |
21183b07 JA |
452 | struct rb_node *rbnext = rb_next(&last->rb_node); |
453 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 454 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 455 | |
21183b07 | 456 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
457 | |
458 | if (rbprev) | |
5e705374 | 459 | prev = rb_entry_rq(rbprev); |
1da177e4 | 460 | |
21183b07 | 461 | if (rbnext) |
5e705374 | 462 | next = rb_entry_rq(rbnext); |
21183b07 JA |
463 | else { |
464 | rbnext = rb_first(&cfqq->sort_list); | |
465 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 466 | next = rb_entry_rq(rbnext); |
21183b07 | 467 | } |
1da177e4 | 468 | |
21183b07 | 469 | return cfq_choose_req(cfqd, next, prev); |
1da177e4 LT |
470 | } |
471 | ||
d9e7620e JA |
472 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
473 | struct cfq_queue *cfqq) | |
1da177e4 | 474 | { |
d9e7620e JA |
475 | /* |
476 | * just an approximation, should be ok. | |
477 | */ | |
67e6b49e JA |
478 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
479 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
480 | } |
481 | ||
498d3aa2 JA |
482 | /* |
483 | * The cfqd->service_tree holds all pending cfq_queue's that have | |
484 | * requests waiting to be processed. It is sorted in the order that | |
485 | * we will service the queues. | |
486 | */ | |
a36e71f9 JA |
487 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
488 | int add_front) | |
d9e7620e | 489 | { |
0871714e JA |
490 | struct rb_node **p, *parent; |
491 | struct cfq_queue *__cfqq; | |
d9e7620e | 492 | unsigned long rb_key; |
498d3aa2 | 493 | int left; |
d9e7620e | 494 | |
0871714e JA |
495 | if (cfq_class_idle(cfqq)) { |
496 | rb_key = CFQ_IDLE_DELAY; | |
497 | parent = rb_last(&cfqd->service_tree.rb); | |
498 | if (parent && parent != &cfqq->rb_node) { | |
499 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
500 | rb_key += __cfqq->rb_key; | |
501 | } else | |
502 | rb_key += jiffies; | |
503 | } else if (!add_front) { | |
edd75ffd JA |
504 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
505 | rb_key += cfqq->slice_resid; | |
506 | cfqq->slice_resid = 0; | |
507 | } else | |
508 | rb_key = 0; | |
1da177e4 | 509 | |
d9e7620e | 510 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 511 | /* |
d9e7620e | 512 | * same position, nothing more to do |
99f9628a | 513 | */ |
d9e7620e JA |
514 | if (rb_key == cfqq->rb_key) |
515 | return; | |
1da177e4 | 516 | |
cc09e299 | 517 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); |
1da177e4 | 518 | } |
d9e7620e | 519 | |
498d3aa2 | 520 | left = 1; |
0871714e JA |
521 | parent = NULL; |
522 | p = &cfqd->service_tree.rb.rb_node; | |
d9e7620e | 523 | while (*p) { |
67060e37 | 524 | struct rb_node **n; |
cc09e299 | 525 | |
d9e7620e JA |
526 | parent = *p; |
527 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
528 | ||
0c534e0a JA |
529 | /* |
530 | * sort RT queues first, we always want to give | |
67060e37 JA |
531 | * preference to them. IDLE queues goes to the back. |
532 | * after that, sort on the next service time. | |
0c534e0a JA |
533 | */ |
534 | if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) | |
67060e37 | 535 | n = &(*p)->rb_left; |
0c534e0a | 536 | else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) |
67060e37 JA |
537 | n = &(*p)->rb_right; |
538 | else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) | |
539 | n = &(*p)->rb_left; | |
540 | else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) | |
541 | n = &(*p)->rb_right; | |
0c534e0a | 542 | else if (rb_key < __cfqq->rb_key) |
67060e37 JA |
543 | n = &(*p)->rb_left; |
544 | else | |
545 | n = &(*p)->rb_right; | |
546 | ||
547 | if (n == &(*p)->rb_right) | |
cc09e299 | 548 | left = 0; |
67060e37 JA |
549 | |
550 | p = n; | |
d9e7620e JA |
551 | } |
552 | ||
cc09e299 JA |
553 | if (left) |
554 | cfqd->service_tree.left = &cfqq->rb_node; | |
555 | ||
d9e7620e JA |
556 | cfqq->rb_key = rb_key; |
557 | rb_link_node(&cfqq->rb_node, parent, p); | |
cc09e299 | 558 | rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); |
1da177e4 LT |
559 | } |
560 | ||
a36e71f9 | 561 | static struct cfq_queue * |
f2d1f0ae JA |
562 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
563 | sector_t sector, struct rb_node **ret_parent, | |
564 | struct rb_node ***rb_link) | |
a36e71f9 | 565 | { |
a36e71f9 JA |
566 | struct rb_node **p, *parent; |
567 | struct cfq_queue *cfqq = NULL; | |
568 | ||
569 | parent = NULL; | |
570 | p = &root->rb_node; | |
571 | while (*p) { | |
572 | struct rb_node **n; | |
573 | ||
574 | parent = *p; | |
575 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
576 | ||
577 | /* | |
578 | * Sort strictly based on sector. Smallest to the left, | |
579 | * largest to the right. | |
580 | */ | |
2e46e8b2 | 581 | if (sector > blk_rq_pos(cfqq->next_rq)) |
a36e71f9 | 582 | n = &(*p)->rb_right; |
2e46e8b2 | 583 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
a36e71f9 JA |
584 | n = &(*p)->rb_left; |
585 | else | |
586 | break; | |
587 | p = n; | |
3ac6c9f8 | 588 | cfqq = NULL; |
a36e71f9 JA |
589 | } |
590 | ||
591 | *ret_parent = parent; | |
592 | if (rb_link) | |
593 | *rb_link = p; | |
3ac6c9f8 | 594 | return cfqq; |
a36e71f9 JA |
595 | } |
596 | ||
597 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
598 | { | |
a36e71f9 JA |
599 | struct rb_node **p, *parent; |
600 | struct cfq_queue *__cfqq; | |
601 | ||
f2d1f0ae JA |
602 | if (cfqq->p_root) { |
603 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
604 | cfqq->p_root = NULL; | |
605 | } | |
a36e71f9 JA |
606 | |
607 | if (cfq_class_idle(cfqq)) | |
608 | return; | |
609 | if (!cfqq->next_rq) | |
610 | return; | |
611 | ||
f2d1f0ae | 612 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
2e46e8b2 TH |
613 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
614 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
3ac6c9f8 JA |
615 | if (!__cfqq) { |
616 | rb_link_node(&cfqq->p_node, parent, p); | |
f2d1f0ae JA |
617 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
618 | } else | |
619 | cfqq->p_root = NULL; | |
a36e71f9 JA |
620 | } |
621 | ||
498d3aa2 JA |
622 | /* |
623 | * Update cfqq's position in the service tree. | |
624 | */ | |
edd75ffd | 625 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 626 | { |
6d048f53 JA |
627 | /* |
628 | * Resorting requires the cfqq to be on the RR list already. | |
629 | */ | |
a36e71f9 | 630 | if (cfq_cfqq_on_rr(cfqq)) { |
edd75ffd | 631 | cfq_service_tree_add(cfqd, cfqq, 0); |
a36e71f9 JA |
632 | cfq_prio_tree_add(cfqd, cfqq); |
633 | } | |
6d048f53 JA |
634 | } |
635 | ||
1da177e4 LT |
636 | /* |
637 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 638 | * the pending list according to last request service |
1da177e4 | 639 | */ |
febffd61 | 640 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 641 | { |
7b679138 | 642 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
3b18152c JA |
643 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
644 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 | 645 | cfqd->busy_queues++; |
3a9a3f6c DS |
646 | if (cfq_class_rt(cfqq)) |
647 | cfqd->busy_rt_queues++; | |
1da177e4 | 648 | |
edd75ffd | 649 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
650 | } |
651 | ||
498d3aa2 JA |
652 | /* |
653 | * Called when the cfqq no longer has requests pending, remove it from | |
654 | * the service tree. | |
655 | */ | |
febffd61 | 656 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 657 | { |
7b679138 | 658 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
3b18152c JA |
659 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
660 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 661 | |
cc09e299 JA |
662 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) |
663 | cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); | |
f2d1f0ae JA |
664 | if (cfqq->p_root) { |
665 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
666 | cfqq->p_root = NULL; | |
667 | } | |
d9e7620e | 668 | |
1da177e4 LT |
669 | BUG_ON(!cfqd->busy_queues); |
670 | cfqd->busy_queues--; | |
3a9a3f6c DS |
671 | if (cfq_class_rt(cfqq)) |
672 | cfqd->busy_rt_queues--; | |
1da177e4 LT |
673 | } |
674 | ||
675 | /* | |
676 | * rb tree support functions | |
677 | */ | |
febffd61 | 678 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 679 | { |
5e705374 | 680 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 681 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 682 | const int sync = rq_is_sync(rq); |
1da177e4 | 683 | |
b4878f24 JA |
684 | BUG_ON(!cfqq->queued[sync]); |
685 | cfqq->queued[sync]--; | |
1da177e4 | 686 | |
5e705374 | 687 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 688 | |
dd67d051 | 689 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 690 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
691 | } |
692 | ||
5e705374 | 693 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 694 | { |
5e705374 | 695 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 696 | struct cfq_data *cfqd = cfqq->cfqd; |
a36e71f9 | 697 | struct request *__alias, *prev; |
1da177e4 | 698 | |
5380a101 | 699 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
700 | |
701 | /* | |
702 | * looks a little odd, but the first insert might return an alias. | |
703 | * if that happens, put the alias on the dispatch list | |
704 | */ | |
21183b07 | 705 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 706 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
707 | |
708 | if (!cfq_cfqq_on_rr(cfqq)) | |
709 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
710 | |
711 | /* | |
712 | * check if this request is a better next-serve candidate | |
713 | */ | |
a36e71f9 | 714 | prev = cfqq->next_rq; |
5044eed4 | 715 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq); |
a36e71f9 JA |
716 | |
717 | /* | |
718 | * adjust priority tree position, if ->next_rq changes | |
719 | */ | |
720 | if (prev != cfqq->next_rq) | |
721 | cfq_prio_tree_add(cfqd, cfqq); | |
722 | ||
5044eed4 | 723 | BUG_ON(!cfqq->next_rq); |
1da177e4 LT |
724 | } |
725 | ||
febffd61 | 726 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 727 | { |
5380a101 JA |
728 | elv_rb_del(&cfqq->sort_list, rq); |
729 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 730 | cfq_add_rq_rb(rq); |
1da177e4 LT |
731 | } |
732 | ||
206dc69b JA |
733 | static struct request * |
734 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 735 | { |
206dc69b | 736 | struct task_struct *tsk = current; |
91fac317 | 737 | struct cfq_io_context *cic; |
206dc69b | 738 | struct cfq_queue *cfqq; |
1da177e4 | 739 | |
4ac845a2 | 740 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
741 | if (!cic) |
742 | return NULL; | |
743 | ||
744 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
745 | if (cfqq) { |
746 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
747 | ||
21183b07 | 748 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 749 | } |
1da177e4 | 750 | |
1da177e4 LT |
751 | return NULL; |
752 | } | |
753 | ||
165125e1 | 754 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 755 | { |
22e2c507 | 756 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 757 | |
b4878f24 | 758 | cfqd->rq_in_driver++; |
7b679138 JA |
759 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
760 | cfqd->rq_in_driver); | |
25776e35 | 761 | |
5b93629b | 762 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1da177e4 LT |
763 | } |
764 | ||
165125e1 | 765 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 766 | { |
b4878f24 JA |
767 | struct cfq_data *cfqd = q->elevator->elevator_data; |
768 | ||
769 | WARN_ON(!cfqd->rq_in_driver); | |
770 | cfqd->rq_in_driver--; | |
7b679138 JA |
771 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
772 | cfqd->rq_in_driver); | |
1da177e4 LT |
773 | } |
774 | ||
b4878f24 | 775 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 776 | { |
5e705374 | 777 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 778 | |
5e705374 JA |
779 | if (cfqq->next_rq == rq) |
780 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 781 | |
b4878f24 | 782 | list_del_init(&rq->queuelist); |
5e705374 | 783 | cfq_del_rq_rb(rq); |
374f84ac | 784 | |
45333d5a | 785 | cfqq->cfqd->rq_queued--; |
374f84ac JA |
786 | if (rq_is_meta(rq)) { |
787 | WARN_ON(!cfqq->meta_pending); | |
788 | cfqq->meta_pending--; | |
789 | } | |
1da177e4 LT |
790 | } |
791 | ||
165125e1 JA |
792 | static int cfq_merge(struct request_queue *q, struct request **req, |
793 | struct bio *bio) | |
1da177e4 LT |
794 | { |
795 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
796 | struct request *__rq; | |
1da177e4 | 797 | |
206dc69b | 798 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 799 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
800 | *req = __rq; |
801 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
802 | } |
803 | ||
804 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
805 | } |
806 | ||
165125e1 | 807 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 808 | int type) |
1da177e4 | 809 | { |
21183b07 | 810 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 811 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 812 | |
5e705374 | 813 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 814 | } |
1da177e4 LT |
815 | } |
816 | ||
817 | static void | |
165125e1 | 818 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
819 | struct request *next) |
820 | { | |
22e2c507 JA |
821 | /* |
822 | * reposition in fifo if next is older than rq | |
823 | */ | |
824 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
825 | time_before(next->start_time, rq->start_time)) | |
826 | list_move(&rq->queuelist, &next->queuelist); | |
827 | ||
b4878f24 | 828 | cfq_remove_request(next); |
22e2c507 JA |
829 | } |
830 | ||
165125e1 | 831 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
832 | struct bio *bio) |
833 | { | |
834 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 835 | struct cfq_io_context *cic; |
da775265 | 836 | struct cfq_queue *cfqq; |
da775265 JA |
837 | |
838 | /* | |
ec8acb69 | 839 | * Disallow merge of a sync bio into an async request. |
da775265 | 840 | */ |
91fac317 | 841 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
da775265 JA |
842 | return 0; |
843 | ||
844 | /* | |
719d3402 JA |
845 | * Lookup the cfqq that this bio will be queued with. Allow |
846 | * merge only if rq is queued there. | |
da775265 | 847 | */ |
4ac845a2 | 848 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 VT |
849 | if (!cic) |
850 | return 0; | |
719d3402 | 851 | |
91fac317 | 852 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
719d3402 JA |
853 | if (cfqq == RQ_CFQQ(rq)) |
854 | return 1; | |
da775265 | 855 | |
ec8acb69 | 856 | return 0; |
da775265 JA |
857 | } |
858 | ||
febffd61 JA |
859 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
860 | struct cfq_queue *cfqq) | |
22e2c507 JA |
861 | { |
862 | if (cfqq) { | |
7b679138 | 863 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
22e2c507 | 864 | cfqq->slice_end = 0; |
2f5cb738 JA |
865 | cfqq->slice_dispatch = 0; |
866 | ||
2f5cb738 | 867 | cfq_clear_cfqq_wait_request(cfqq); |
b029195d | 868 | cfq_clear_cfqq_must_dispatch(cfqq); |
3b18152c JA |
869 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
870 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 871 | cfq_mark_cfqq_slice_new(cfqq); |
2f5cb738 JA |
872 | |
873 | del_timer(&cfqd->idle_slice_timer); | |
22e2c507 JA |
874 | } |
875 | ||
876 | cfqd->active_queue = cfqq; | |
877 | } | |
878 | ||
7b14e3b5 JA |
879 | /* |
880 | * current cfqq expired its slice (or was too idle), select new one | |
881 | */ | |
882 | static void | |
883 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
6084cdda | 884 | int timed_out) |
7b14e3b5 | 885 | { |
7b679138 JA |
886 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
887 | ||
7b14e3b5 JA |
888 | if (cfq_cfqq_wait_request(cfqq)) |
889 | del_timer(&cfqd->idle_slice_timer); | |
890 | ||
7b14e3b5 JA |
891 | cfq_clear_cfqq_wait_request(cfqq); |
892 | ||
893 | /* | |
6084cdda | 894 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 895 | */ |
7b679138 | 896 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
c5b680f3 | 897 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b679138 JA |
898 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
899 | } | |
7b14e3b5 | 900 | |
edd75ffd | 901 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
902 | |
903 | if (cfqq == cfqd->active_queue) | |
904 | cfqd->active_queue = NULL; | |
905 | ||
906 | if (cfqd->active_cic) { | |
907 | put_io_context(cfqd->active_cic->ioc); | |
908 | cfqd->active_cic = NULL; | |
909 | } | |
7b14e3b5 JA |
910 | } |
911 | ||
6084cdda | 912 | static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out) |
7b14e3b5 JA |
913 | { |
914 | struct cfq_queue *cfqq = cfqd->active_queue; | |
915 | ||
916 | if (cfqq) | |
6084cdda | 917 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
918 | } |
919 | ||
498d3aa2 JA |
920 | /* |
921 | * Get next queue for service. Unless we have a queue preemption, | |
922 | * we'll simply select the first cfqq in the service tree. | |
923 | */ | |
6d048f53 | 924 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 925 | { |
edd75ffd JA |
926 | if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) |
927 | return NULL; | |
d9e7620e | 928 | |
0871714e | 929 | return cfq_rb_first(&cfqd->service_tree); |
6d048f53 JA |
930 | } |
931 | ||
498d3aa2 JA |
932 | /* |
933 | * Get and set a new active queue for service. | |
934 | */ | |
a36e71f9 JA |
935 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
936 | struct cfq_queue *cfqq) | |
6d048f53 | 937 | { |
a36e71f9 JA |
938 | if (!cfqq) { |
939 | cfqq = cfq_get_next_queue(cfqd); | |
940 | if (cfqq) | |
941 | cfq_clear_cfqq_coop(cfqq); | |
942 | } | |
6d048f53 | 943 | |
22e2c507 | 944 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 945 | return cfqq; |
22e2c507 JA |
946 | } |
947 | ||
d9e7620e JA |
948 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
949 | struct request *rq) | |
950 | { | |
83096ebf TH |
951 | if (blk_rq_pos(rq) >= cfqd->last_position) |
952 | return blk_rq_pos(rq) - cfqd->last_position; | |
d9e7620e | 953 | else |
83096ebf | 954 | return cfqd->last_position - blk_rq_pos(rq); |
d9e7620e JA |
955 | } |
956 | ||
04dc6e71 JM |
957 | #define CIC_SEEK_THR 8 * 1024 |
958 | #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR) | |
959 | ||
6d048f53 JA |
960 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) |
961 | { | |
962 | struct cfq_io_context *cic = cfqd->active_cic; | |
04dc6e71 | 963 | sector_t sdist = cic->seek_mean; |
6d048f53 JA |
964 | |
965 | if (!sample_valid(cic->seek_samples)) | |
04dc6e71 | 966 | sdist = CIC_SEEK_THR; |
6d048f53 | 967 | |
04dc6e71 | 968 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
6d048f53 JA |
969 | } |
970 | ||
a36e71f9 JA |
971 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
972 | struct cfq_queue *cur_cfqq) | |
973 | { | |
f2d1f0ae | 974 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
a36e71f9 JA |
975 | struct rb_node *parent, *node; |
976 | struct cfq_queue *__cfqq; | |
977 | sector_t sector = cfqd->last_position; | |
978 | ||
979 | if (RB_EMPTY_ROOT(root)) | |
980 | return NULL; | |
981 | ||
982 | /* | |
983 | * First, if we find a request starting at the end of the last | |
984 | * request, choose it. | |
985 | */ | |
f2d1f0ae | 986 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
a36e71f9 JA |
987 | if (__cfqq) |
988 | return __cfqq; | |
989 | ||
990 | /* | |
991 | * If the exact sector wasn't found, the parent of the NULL leaf | |
992 | * will contain the closest sector. | |
993 | */ | |
994 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
995 | if (cfq_rq_close(cfqd, __cfqq->next_rq)) | |
996 | return __cfqq; | |
997 | ||
2e46e8b2 | 998 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
a36e71f9 JA |
999 | node = rb_next(&__cfqq->p_node); |
1000 | else | |
1001 | node = rb_prev(&__cfqq->p_node); | |
1002 | if (!node) | |
1003 | return NULL; | |
1004 | ||
1005 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
1006 | if (cfq_rq_close(cfqd, __cfqq->next_rq)) | |
1007 | return __cfqq; | |
1008 | ||
1009 | return NULL; | |
1010 | } | |
1011 | ||
1012 | /* | |
1013 | * cfqd - obvious | |
1014 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1015 | * closely cooperating with itself. | |
1016 | * | |
1017 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1018 | * one request, and that cfqd->last_position reflects a position on the disk | |
1019 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1020 | * assumption. | |
1021 | */ | |
1022 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
1023 | struct cfq_queue *cur_cfqq, | |
1024 | int probe) | |
6d048f53 | 1025 | { |
a36e71f9 JA |
1026 | struct cfq_queue *cfqq; |
1027 | ||
1028 | /* | |
1029 | * A valid cfq_io_context is necessary to compare requests against | |
1030 | * the seek_mean of the current cfqq. | |
1031 | */ | |
1032 | if (!cfqd->active_cic) | |
1033 | return NULL; | |
1034 | ||
6d048f53 | 1035 | /* |
d9e7620e JA |
1036 | * We should notice if some of the queues are cooperating, eg |
1037 | * working closely on the same area of the disk. In that case, | |
1038 | * we can group them together and don't waste time idling. | |
6d048f53 | 1039 | */ |
a36e71f9 JA |
1040 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1041 | if (!cfqq) | |
1042 | return NULL; | |
1043 | ||
1044 | if (cfq_cfqq_coop(cfqq)) | |
1045 | return NULL; | |
1046 | ||
1047 | if (!probe) | |
1048 | cfq_mark_cfqq_coop(cfqq); | |
1049 | return cfqq; | |
6d048f53 JA |
1050 | } |
1051 | ||
6d048f53 | 1052 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 1053 | { |
1792669c | 1054 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 1055 | struct cfq_io_context *cic; |
7b14e3b5 JA |
1056 | unsigned long sl; |
1057 | ||
a68bbddb | 1058 | /* |
f7d7b7a7 JA |
1059 | * SSD device without seek penalty, disable idling. But only do so |
1060 | * for devices that support queuing, otherwise we still have a problem | |
1061 | * with sync vs async workloads. | |
a68bbddb | 1062 | */ |
f7d7b7a7 | 1063 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
a68bbddb JA |
1064 | return; |
1065 | ||
dd67d051 | 1066 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 1067 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
1068 | |
1069 | /* | |
1070 | * idle is disabled, either manually or by past process history | |
1071 | */ | |
6d048f53 JA |
1072 | if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) |
1073 | return; | |
1074 | ||
7b679138 JA |
1075 | /* |
1076 | * still requests with the driver, don't idle | |
1077 | */ | |
1078 | if (cfqd->rq_in_driver) | |
1079 | return; | |
1080 | ||
22e2c507 JA |
1081 | /* |
1082 | * task has exited, don't wait | |
1083 | */ | |
206dc69b | 1084 | cic = cfqd->active_cic; |
66dac98e | 1085 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
1086 | return; |
1087 | ||
3b18152c | 1088 | cfq_mark_cfqq_wait_request(cfqq); |
22e2c507 | 1089 | |
206dc69b JA |
1090 | /* |
1091 | * we don't want to idle for seeks, but we do want to allow | |
1092 | * fair distribution of slice time for a process doing back-to-back | |
1093 | * seeks. so allow a little bit of time for him to submit a new rq | |
1094 | */ | |
6d048f53 | 1095 | sl = cfqd->cfq_slice_idle; |
caaa5f9f | 1096 | if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) |
d9e7620e | 1097 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
206dc69b | 1098 | |
7b14e3b5 | 1099 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
9481ffdc | 1100 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
1da177e4 LT |
1101 | } |
1102 | ||
498d3aa2 JA |
1103 | /* |
1104 | * Move request from internal lists to the request queue dispatch list. | |
1105 | */ | |
165125e1 | 1106 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 1107 | { |
3ed9a296 | 1108 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1109 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1110 | |
7b679138 JA |
1111 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
1112 | ||
5380a101 | 1113 | cfq_remove_request(rq); |
6d048f53 | 1114 | cfqq->dispatched++; |
5380a101 | 1115 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
1116 | |
1117 | if (cfq_cfqq_sync(cfqq)) | |
1118 | cfqd->sync_flight++; | |
1da177e4 LT |
1119 | } |
1120 | ||
1121 | /* | |
1122 | * return expired entry, or NULL to just start from scratch in rbtree | |
1123 | */ | |
febffd61 | 1124 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 LT |
1125 | { |
1126 | struct cfq_data *cfqd = cfqq->cfqd; | |
22e2c507 | 1127 | struct request *rq; |
89850f7e | 1128 | int fifo; |
1da177e4 | 1129 | |
3b18152c | 1130 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 1131 | return NULL; |
cb887411 JA |
1132 | |
1133 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1134 | ||
89850f7e JA |
1135 | if (list_empty(&cfqq->fifo)) |
1136 | return NULL; | |
1da177e4 | 1137 | |
6d048f53 | 1138 | fifo = cfq_cfqq_sync(cfqq); |
89850f7e | 1139 | rq = rq_entry_fifo(cfqq->fifo.next); |
1da177e4 | 1140 | |
6d048f53 | 1141 | if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) |
7b679138 | 1142 | rq = NULL; |
1da177e4 | 1143 | |
7b679138 | 1144 | cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq); |
6d048f53 | 1145 | return rq; |
1da177e4 LT |
1146 | } |
1147 | ||
22e2c507 JA |
1148 | static inline int |
1149 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1150 | { | |
1151 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1152 | |
22e2c507 | 1153 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1154 | |
22e2c507 | 1155 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1156 | } |
1157 | ||
22e2c507 | 1158 | /* |
498d3aa2 JA |
1159 | * Select a queue for service. If we have a current active queue, |
1160 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 1161 | */ |
1b5ed5e1 | 1162 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1163 | { |
a36e71f9 | 1164 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
1da177e4 | 1165 | |
22e2c507 JA |
1166 | cfqq = cfqd->active_queue; |
1167 | if (!cfqq) | |
1168 | goto new_queue; | |
1da177e4 | 1169 | |
22e2c507 | 1170 | /* |
6d048f53 | 1171 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 1172 | */ |
b029195d | 1173 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
3b18152c | 1174 | goto expire; |
1da177e4 | 1175 | |
3a9a3f6c DS |
1176 | /* |
1177 | * If we have a RT cfqq waiting, then we pre-empt the current non-rt | |
1178 | * cfqq. | |
1179 | */ | |
1180 | if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) { | |
1181 | /* | |
1182 | * We simulate this as cfqq timed out so that it gets to bank | |
1183 | * the remaining of its time slice. | |
1184 | */ | |
1185 | cfq_log_cfqq(cfqd, cfqq, "preempt"); | |
1186 | cfq_slice_expired(cfqd, 1); | |
1187 | goto new_queue; | |
1188 | } | |
1189 | ||
22e2c507 | 1190 | /* |
6d048f53 JA |
1191 | * The active queue has requests and isn't expired, allow it to |
1192 | * dispatch. | |
22e2c507 | 1193 | */ |
dd67d051 | 1194 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1195 | goto keep_queue; |
6d048f53 | 1196 | |
a36e71f9 JA |
1197 | /* |
1198 | * If another queue has a request waiting within our mean seek | |
1199 | * distance, let it run. The expire code will check for close | |
1200 | * cooperators and put the close queue at the front of the service | |
1201 | * tree. | |
1202 | */ | |
1203 | new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0); | |
1204 | if (new_cfqq) | |
1205 | goto expire; | |
1206 | ||
6d048f53 JA |
1207 | /* |
1208 | * No requests pending. If the active queue still has requests in | |
1209 | * flight or is idling for a new request, allow either of these | |
1210 | * conditions to happen (or time out) before selecting a new queue. | |
1211 | */ | |
cc197479 JA |
1212 | if (timer_pending(&cfqd->idle_slice_timer) || |
1213 | (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { | |
caaa5f9f JA |
1214 | cfqq = NULL; |
1215 | goto keep_queue; | |
22e2c507 JA |
1216 | } |
1217 | ||
3b18152c | 1218 | expire: |
6084cdda | 1219 | cfq_slice_expired(cfqd, 0); |
3b18152c | 1220 | new_queue: |
a36e71f9 | 1221 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
22e2c507 | 1222 | keep_queue: |
3b18152c | 1223 | return cfqq; |
22e2c507 JA |
1224 | } |
1225 | ||
febffd61 | 1226 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1227 | { |
1228 | int dispatched = 0; | |
1229 | ||
1230 | while (cfqq->next_rq) { | |
1231 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1232 | dispatched++; | |
1233 | } | |
1234 | ||
1235 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1236 | return dispatched; | |
1237 | } | |
1238 | ||
498d3aa2 JA |
1239 | /* |
1240 | * Drain our current requests. Used for barriers and when switching | |
1241 | * io schedulers on-the-fly. | |
1242 | */ | |
d9e7620e | 1243 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1244 | { |
0871714e | 1245 | struct cfq_queue *cfqq; |
d9e7620e | 1246 | int dispatched = 0; |
1b5ed5e1 | 1247 | |
0871714e | 1248 | while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL) |
d9e7620e | 1249 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1b5ed5e1 | 1250 | |
6084cdda | 1251 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1252 | |
1253 | BUG_ON(cfqd->busy_queues); | |
1254 | ||
6923715a | 1255 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
1b5ed5e1 TH |
1256 | return dispatched; |
1257 | } | |
1258 | ||
2f5cb738 JA |
1259 | /* |
1260 | * Dispatch a request from cfqq, moving them to the request queue | |
1261 | * dispatch list. | |
1262 | */ | |
1263 | static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1264 | { | |
1265 | struct request *rq; | |
1266 | ||
1267 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1268 | ||
1269 | /* | |
1270 | * follow expired path, else get first next available | |
1271 | */ | |
1272 | rq = cfq_check_fifo(cfqq); | |
1273 | if (!rq) | |
1274 | rq = cfqq->next_rq; | |
1275 | ||
1276 | /* | |
1277 | * insert request into driver dispatch list | |
1278 | */ | |
1279 | cfq_dispatch_insert(cfqd->queue, rq); | |
1280 | ||
1281 | if (!cfqd->active_cic) { | |
1282 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1283 | ||
d9c7d394 | 1284 | atomic_long_inc(&cic->ioc->refcount); |
2f5cb738 JA |
1285 | cfqd->active_cic = cic; |
1286 | } | |
1287 | } | |
1288 | ||
1289 | /* | |
1290 | * Find the cfqq that we need to service and move a request from that to the | |
1291 | * dispatch list | |
1292 | */ | |
165125e1 | 1293 | static int cfq_dispatch_requests(struct request_queue *q, int force) |
22e2c507 JA |
1294 | { |
1295 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
6d048f53 | 1296 | struct cfq_queue *cfqq; |
2f5cb738 | 1297 | unsigned int max_dispatch; |
22e2c507 JA |
1298 | |
1299 | if (!cfqd->busy_queues) | |
1300 | return 0; | |
1301 | ||
1b5ed5e1 TH |
1302 | if (unlikely(force)) |
1303 | return cfq_forced_dispatch(cfqd); | |
1304 | ||
2f5cb738 JA |
1305 | cfqq = cfq_select_queue(cfqd); |
1306 | if (!cfqq) | |
1307 | return 0; | |
1308 | ||
1309 | /* | |
1310 | * If this is an async queue and we have sync IO in flight, let it wait | |
1311 | */ | |
1312 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) | |
1313 | return 0; | |
1314 | ||
1315 | max_dispatch = cfqd->cfq_quantum; | |
1316 | if (cfq_class_idle(cfqq)) | |
1317 | max_dispatch = 1; | |
b4878f24 | 1318 | |
2f5cb738 JA |
1319 | /* |
1320 | * Does this cfqq already have too much IO in flight? | |
1321 | */ | |
1322 | if (cfqq->dispatched >= max_dispatch) { | |
1323 | /* | |
1324 | * idle queue must always only have a single IO in flight | |
1325 | */ | |
3ed9a296 | 1326 | if (cfq_class_idle(cfqq)) |
2f5cb738 | 1327 | return 0; |
3ed9a296 | 1328 | |
2f5cb738 JA |
1329 | /* |
1330 | * We have other queues, don't allow more IO from this one | |
1331 | */ | |
1332 | if (cfqd->busy_queues > 1) | |
1333 | return 0; | |
9ede209e | 1334 | |
2f5cb738 JA |
1335 | /* |
1336 | * we are the only queue, allow up to 4 times of 'quantum' | |
1337 | */ | |
1338 | if (cfqq->dispatched >= 4 * max_dispatch) | |
1339 | return 0; | |
1340 | } | |
3ed9a296 | 1341 | |
2f5cb738 JA |
1342 | /* |
1343 | * Dispatch a request from this cfqq | |
1344 | */ | |
1345 | cfq_dispatch_request(cfqd, cfqq); | |
1346 | cfqq->slice_dispatch++; | |
b029195d | 1347 | cfq_clear_cfqq_must_dispatch(cfqq); |
22e2c507 | 1348 | |
2f5cb738 JA |
1349 | /* |
1350 | * expire an async queue immediately if it has used up its slice. idle | |
1351 | * queue always expire after 1 dispatch round. | |
1352 | */ | |
1353 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
1354 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1355 | cfq_class_idle(cfqq))) { | |
1356 | cfqq->slice_end = jiffies + 1; | |
1357 | cfq_slice_expired(cfqd, 0); | |
1da177e4 LT |
1358 | } |
1359 | ||
2f5cb738 JA |
1360 | cfq_log(cfqd, "dispatched a request"); |
1361 | return 1; | |
1da177e4 LT |
1362 | } |
1363 | ||
1da177e4 | 1364 | /* |
5e705374 JA |
1365 | * task holds one reference to the queue, dropped when task exits. each rq |
1366 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1367 | * |
1368 | * queue lock must be held here. | |
1369 | */ | |
1370 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1371 | { | |
22e2c507 JA |
1372 | struct cfq_data *cfqd = cfqq->cfqd; |
1373 | ||
1374 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1375 | |
1376 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1377 | return; | |
1378 | ||
7b679138 | 1379 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
1da177e4 | 1380 | BUG_ON(rb_first(&cfqq->sort_list)); |
22e2c507 | 1381 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1382 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1383 | |
28f95cbc | 1384 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1385 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1386 | cfq_schedule_dispatch(cfqd); |
1387 | } | |
22e2c507 | 1388 | |
1da177e4 LT |
1389 | kmem_cache_free(cfq_pool, cfqq); |
1390 | } | |
1391 | ||
d6de8be7 JA |
1392 | /* |
1393 | * Must always be called with the rcu_read_lock() held | |
1394 | */ | |
07416d29 JA |
1395 | static void |
1396 | __call_for_each_cic(struct io_context *ioc, | |
1397 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1398 | { | |
1399 | struct cfq_io_context *cic; | |
1400 | struct hlist_node *n; | |
1401 | ||
1402 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
1403 | func(ioc, cic); | |
1404 | } | |
1405 | ||
4ac845a2 | 1406 | /* |
34e6bbf2 | 1407 | * Call func for each cic attached to this ioc. |
4ac845a2 | 1408 | */ |
34e6bbf2 | 1409 | static void |
4ac845a2 JA |
1410 | call_for_each_cic(struct io_context *ioc, |
1411 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1412 | { |
4ac845a2 | 1413 | rcu_read_lock(); |
07416d29 | 1414 | __call_for_each_cic(ioc, func); |
4ac845a2 | 1415 | rcu_read_unlock(); |
34e6bbf2 FC |
1416 | } |
1417 | ||
1418 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
1419 | { | |
1420 | struct cfq_io_context *cic; | |
1421 | ||
1422 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
1423 | ||
1424 | kmem_cache_free(cfq_ioc_pool, cic); | |
1425 | elv_ioc_count_dec(ioc_count); | |
1426 | ||
9a11b4ed JA |
1427 | if (ioc_gone) { |
1428 | /* | |
1429 | * CFQ scheduler is exiting, grab exit lock and check | |
1430 | * the pending io context count. If it hits zero, | |
1431 | * complete ioc_gone and set it back to NULL | |
1432 | */ | |
1433 | spin_lock(&ioc_gone_lock); | |
1434 | if (ioc_gone && !elv_ioc_count_read(ioc_count)) { | |
1435 | complete(ioc_gone); | |
1436 | ioc_gone = NULL; | |
1437 | } | |
1438 | spin_unlock(&ioc_gone_lock); | |
1439 | } | |
34e6bbf2 | 1440 | } |
4ac845a2 | 1441 | |
34e6bbf2 FC |
1442 | static void cfq_cic_free(struct cfq_io_context *cic) |
1443 | { | |
1444 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
4ac845a2 JA |
1445 | } |
1446 | ||
1447 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1448 | { | |
1449 | unsigned long flags; | |
1450 | ||
1451 | BUG_ON(!cic->dead_key); | |
1452 | ||
1453 | spin_lock_irqsave(&ioc->lock, flags); | |
1454 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
ffc4e759 | 1455 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1456 | spin_unlock_irqrestore(&ioc->lock, flags); |
1457 | ||
34e6bbf2 | 1458 | cfq_cic_free(cic); |
4ac845a2 JA |
1459 | } |
1460 | ||
d6de8be7 JA |
1461 | /* |
1462 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
1463 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
1464 | * and ->trim() which is called with the task lock held | |
1465 | */ | |
4ac845a2 JA |
1466 | static void cfq_free_io_context(struct io_context *ioc) |
1467 | { | |
4ac845a2 | 1468 | /* |
34e6bbf2 FC |
1469 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
1470 | * so no more cic's are allowed to be linked into this ioc. So it | |
1471 | * should be ok to iterate over the known list, we will see all cic's | |
1472 | * since no new ones are added. | |
4ac845a2 | 1473 | */ |
07416d29 | 1474 | __call_for_each_cic(ioc, cic_free_func); |
1da177e4 LT |
1475 | } |
1476 | ||
89850f7e | 1477 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1478 | { |
28f95cbc | 1479 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1480 | __cfq_slice_expired(cfqd, cfqq, 0); |
28f95cbc JA |
1481 | cfq_schedule_dispatch(cfqd); |
1482 | } | |
22e2c507 | 1483 | |
89850f7e JA |
1484 | cfq_put_queue(cfqq); |
1485 | } | |
22e2c507 | 1486 | |
89850f7e JA |
1487 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1488 | struct cfq_io_context *cic) | |
1489 | { | |
4faa3c81 FC |
1490 | struct io_context *ioc = cic->ioc; |
1491 | ||
fc46379d | 1492 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1493 | |
1494 | /* | |
1495 | * Make sure key == NULL is seen for dead queues | |
1496 | */ | |
fc46379d | 1497 | smp_wmb(); |
4ac845a2 | 1498 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1499 | cic->key = NULL; |
1500 | ||
4faa3c81 FC |
1501 | if (ioc->ioc_data == cic) |
1502 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
1503 | ||
ff6657c6 JA |
1504 | if (cic->cfqq[BLK_RW_ASYNC]) { |
1505 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
1506 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
12a05732 AV |
1507 | } |
1508 | ||
ff6657c6 JA |
1509 | if (cic->cfqq[BLK_RW_SYNC]) { |
1510 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
1511 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
12a05732 | 1512 | } |
89850f7e JA |
1513 | } |
1514 | ||
4ac845a2 JA |
1515 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1516 | struct cfq_io_context *cic) | |
89850f7e JA |
1517 | { |
1518 | struct cfq_data *cfqd = cic->key; | |
1519 | ||
89850f7e | 1520 | if (cfqd) { |
165125e1 | 1521 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1522 | unsigned long flags; |
89850f7e | 1523 | |
4ac845a2 | 1524 | spin_lock_irqsave(q->queue_lock, flags); |
62c1fe9d JA |
1525 | |
1526 | /* | |
1527 | * Ensure we get a fresh copy of the ->key to prevent | |
1528 | * race between exiting task and queue | |
1529 | */ | |
1530 | smp_read_barrier_depends(); | |
1531 | if (cic->key) | |
1532 | __cfq_exit_single_io_context(cfqd, cic); | |
1533 | ||
4ac845a2 | 1534 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1535 | } |
1da177e4 LT |
1536 | } |
1537 | ||
498d3aa2 JA |
1538 | /* |
1539 | * The process that ioc belongs to has exited, we need to clean up | |
1540 | * and put the internal structures we have that belongs to that process. | |
1541 | */ | |
e2d74ac0 | 1542 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1543 | { |
4ac845a2 | 1544 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
1da177e4 LT |
1545 | } |
1546 | ||
22e2c507 | 1547 | static struct cfq_io_context * |
8267e268 | 1548 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1549 | { |
b5deef90 | 1550 | struct cfq_io_context *cic; |
1da177e4 | 1551 | |
94f6030c CL |
1552 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1553 | cfqd->queue->node); | |
1da177e4 | 1554 | if (cic) { |
22e2c507 | 1555 | cic->last_end_request = jiffies; |
553698f9 | 1556 | INIT_LIST_HEAD(&cic->queue_list); |
ffc4e759 | 1557 | INIT_HLIST_NODE(&cic->cic_list); |
22e2c507 JA |
1558 | cic->dtor = cfq_free_io_context; |
1559 | cic->exit = cfq_exit_io_context; | |
4050cf16 | 1560 | elv_ioc_count_inc(ioc_count); |
1da177e4 LT |
1561 | } |
1562 | ||
1563 | return cic; | |
1564 | } | |
1565 | ||
fd0928df | 1566 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1567 | { |
1568 | struct task_struct *tsk = current; | |
1569 | int ioprio_class; | |
1570 | ||
3b18152c | 1571 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1572 | return; |
1573 | ||
fd0928df | 1574 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 | 1575 | switch (ioprio_class) { |
fe094d98 JA |
1576 | default: |
1577 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1578 | case IOPRIO_CLASS_NONE: | |
1579 | /* | |
6d63c275 | 1580 | * no prio set, inherit CPU scheduling settings |
fe094d98 JA |
1581 | */ |
1582 | cfqq->ioprio = task_nice_ioprio(tsk); | |
6d63c275 | 1583 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
fe094d98 JA |
1584 | break; |
1585 | case IOPRIO_CLASS_RT: | |
1586 | cfqq->ioprio = task_ioprio(ioc); | |
1587 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1588 | break; | |
1589 | case IOPRIO_CLASS_BE: | |
1590 | cfqq->ioprio = task_ioprio(ioc); | |
1591 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1592 | break; | |
1593 | case IOPRIO_CLASS_IDLE: | |
1594 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1595 | cfqq->ioprio = 7; | |
1596 | cfq_clear_cfqq_idle_window(cfqq); | |
1597 | break; | |
22e2c507 JA |
1598 | } |
1599 | ||
1600 | /* | |
1601 | * keep track of original prio settings in case we have to temporarily | |
1602 | * elevate the priority of this queue | |
1603 | */ | |
1604 | cfqq->org_ioprio = cfqq->ioprio; | |
1605 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1606 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1607 | } |
1608 | ||
febffd61 | 1609 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 1610 | { |
478a82b0 AV |
1611 | struct cfq_data *cfqd = cic->key; |
1612 | struct cfq_queue *cfqq; | |
c1b707d2 | 1613 | unsigned long flags; |
35e6077c | 1614 | |
caaa5f9f JA |
1615 | if (unlikely(!cfqd)) |
1616 | return; | |
1617 | ||
c1b707d2 | 1618 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f | 1619 | |
ff6657c6 | 1620 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
caaa5f9f JA |
1621 | if (cfqq) { |
1622 | struct cfq_queue *new_cfqq; | |
ff6657c6 JA |
1623 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
1624 | GFP_ATOMIC); | |
caaa5f9f | 1625 | if (new_cfqq) { |
ff6657c6 | 1626 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
caaa5f9f JA |
1627 | cfq_put_queue(cfqq); |
1628 | } | |
22e2c507 | 1629 | } |
caaa5f9f | 1630 | |
ff6657c6 | 1631 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
caaa5f9f JA |
1632 | if (cfqq) |
1633 | cfq_mark_cfqq_prio_changed(cfqq); | |
1634 | ||
c1b707d2 | 1635 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
1636 | } |
1637 | ||
fc46379d | 1638 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 1639 | { |
4ac845a2 | 1640 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 1641 | ioc->ioprio_changed = 0; |
22e2c507 JA |
1642 | } |
1643 | ||
1644 | static struct cfq_queue * | |
15c31be4 | 1645 | cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync, |
fd0928df | 1646 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 1647 | { |
22e2c507 | 1648 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 1649 | struct cfq_io_context *cic; |
22e2c507 JA |
1650 | |
1651 | retry: | |
4ac845a2 | 1652 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
1653 | /* cic always exists here */ |
1654 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 JA |
1655 | |
1656 | if (!cfqq) { | |
1657 | if (new_cfqq) { | |
1658 | cfqq = new_cfqq; | |
1659 | new_cfqq = NULL; | |
1660 | } else if (gfp_mask & __GFP_WAIT) { | |
89850f7e JA |
1661 | /* |
1662 | * Inform the allocator of the fact that we will | |
1663 | * just repeat this allocation if it fails, to allow | |
1664 | * the allocator to do whatever it needs to attempt to | |
1665 | * free memory. | |
1666 | */ | |
22e2c507 | 1667 | spin_unlock_irq(cfqd->queue->queue_lock); |
94f6030c CL |
1668 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
1669 | gfp_mask | __GFP_NOFAIL | __GFP_ZERO, | |
1670 | cfqd->queue->node); | |
22e2c507 JA |
1671 | spin_lock_irq(cfqd->queue->queue_lock); |
1672 | goto retry; | |
1673 | } else { | |
94f6030c CL |
1674 | cfqq = kmem_cache_alloc_node(cfq_pool, |
1675 | gfp_mask | __GFP_ZERO, | |
1676 | cfqd->queue->node); | |
22e2c507 JA |
1677 | if (!cfqq) |
1678 | goto out; | |
1679 | } | |
1680 | ||
d9e7620e | 1681 | RB_CLEAR_NODE(&cfqq->rb_node); |
a36e71f9 | 1682 | RB_CLEAR_NODE(&cfqq->p_node); |
22e2c507 JA |
1683 | INIT_LIST_HEAD(&cfqq->fifo); |
1684 | ||
22e2c507 JA |
1685 | atomic_set(&cfqq->ref, 0); |
1686 | cfqq->cfqd = cfqd; | |
c5b680f3 | 1687 | |
3b18152c | 1688 | cfq_mark_cfqq_prio_changed(cfqq); |
91fac317 | 1689 | |
fd0928df | 1690 | cfq_init_prio_data(cfqq, ioc); |
0871714e JA |
1691 | |
1692 | if (is_sync) { | |
1693 | if (!cfq_class_idle(cfqq)) | |
1694 | cfq_mark_cfqq_idle_window(cfqq); | |
1695 | cfq_mark_cfqq_sync(cfqq); | |
1696 | } | |
7b679138 JA |
1697 | cfqq->pid = current->pid; |
1698 | cfq_log_cfqq(cfqd, cfqq, "alloced"); | |
22e2c507 JA |
1699 | } |
1700 | ||
1701 | if (new_cfqq) | |
1702 | kmem_cache_free(cfq_pool, new_cfqq); | |
1703 | ||
22e2c507 JA |
1704 | out: |
1705 | WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); | |
1706 | return cfqq; | |
1707 | } | |
1708 | ||
c2dea2d1 VT |
1709 | static struct cfq_queue ** |
1710 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
1711 | { | |
fe094d98 | 1712 | switch (ioprio_class) { |
c2dea2d1 VT |
1713 | case IOPRIO_CLASS_RT: |
1714 | return &cfqd->async_cfqq[0][ioprio]; | |
1715 | case IOPRIO_CLASS_BE: | |
1716 | return &cfqd->async_cfqq[1][ioprio]; | |
1717 | case IOPRIO_CLASS_IDLE: | |
1718 | return &cfqd->async_idle_cfqq; | |
1719 | default: | |
1720 | BUG(); | |
1721 | } | |
1722 | } | |
1723 | ||
15c31be4 | 1724 | static struct cfq_queue * |
fd0928df | 1725 | cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc, |
15c31be4 JA |
1726 | gfp_t gfp_mask) |
1727 | { | |
fd0928df JA |
1728 | const int ioprio = task_ioprio(ioc); |
1729 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 1730 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
1731 | struct cfq_queue *cfqq = NULL; |
1732 | ||
c2dea2d1 VT |
1733 | if (!is_sync) { |
1734 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
1735 | cfqq = *async_cfqq; | |
1736 | } | |
1737 | ||
0a0836a0 | 1738 | if (!cfqq) { |
fd0928df | 1739 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
0a0836a0 ON |
1740 | if (!cfqq) |
1741 | return NULL; | |
1742 | } | |
15c31be4 JA |
1743 | |
1744 | /* | |
1745 | * pin the queue now that it's allocated, scheduler exit will prune it | |
1746 | */ | |
c2dea2d1 | 1747 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 1748 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 1749 | *async_cfqq = cfqq; |
15c31be4 JA |
1750 | } |
1751 | ||
1752 | atomic_inc(&cfqq->ref); | |
1753 | return cfqq; | |
1754 | } | |
1755 | ||
498d3aa2 JA |
1756 | /* |
1757 | * We drop cfq io contexts lazily, so we may find a dead one. | |
1758 | */ | |
dbecf3ab | 1759 | static void |
4ac845a2 JA |
1760 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
1761 | struct cfq_io_context *cic) | |
dbecf3ab | 1762 | { |
4ac845a2 JA |
1763 | unsigned long flags; |
1764 | ||
fc46379d | 1765 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 1766 | |
4ac845a2 JA |
1767 | spin_lock_irqsave(&ioc->lock, flags); |
1768 | ||
4faa3c81 | 1769 | BUG_ON(ioc->ioc_data == cic); |
597bc485 | 1770 | |
4ac845a2 | 1771 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
ffc4e759 | 1772 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1773 | spin_unlock_irqrestore(&ioc->lock, flags); |
1774 | ||
1775 | cfq_cic_free(cic); | |
dbecf3ab OH |
1776 | } |
1777 | ||
e2d74ac0 | 1778 | static struct cfq_io_context * |
4ac845a2 | 1779 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 1780 | { |
e2d74ac0 | 1781 | struct cfq_io_context *cic; |
d6de8be7 | 1782 | unsigned long flags; |
4ac845a2 | 1783 | void *k; |
e2d74ac0 | 1784 | |
91fac317 VT |
1785 | if (unlikely(!ioc)) |
1786 | return NULL; | |
1787 | ||
d6de8be7 JA |
1788 | rcu_read_lock(); |
1789 | ||
597bc485 JA |
1790 | /* |
1791 | * we maintain a last-hit cache, to avoid browsing over the tree | |
1792 | */ | |
4ac845a2 | 1793 | cic = rcu_dereference(ioc->ioc_data); |
d6de8be7 JA |
1794 | if (cic && cic->key == cfqd) { |
1795 | rcu_read_unlock(); | |
597bc485 | 1796 | return cic; |
d6de8be7 | 1797 | } |
597bc485 | 1798 | |
4ac845a2 | 1799 | do { |
4ac845a2 JA |
1800 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
1801 | rcu_read_unlock(); | |
1802 | if (!cic) | |
1803 | break; | |
be3b0753 OH |
1804 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
1805 | k = cic->key; | |
1806 | if (unlikely(!k)) { | |
4ac845a2 | 1807 | cfq_drop_dead_cic(cfqd, ioc, cic); |
d6de8be7 | 1808 | rcu_read_lock(); |
4ac845a2 | 1809 | continue; |
dbecf3ab | 1810 | } |
e2d74ac0 | 1811 | |
d6de8be7 | 1812 | spin_lock_irqsave(&ioc->lock, flags); |
4ac845a2 | 1813 | rcu_assign_pointer(ioc->ioc_data, cic); |
d6de8be7 | 1814 | spin_unlock_irqrestore(&ioc->lock, flags); |
4ac845a2 JA |
1815 | break; |
1816 | } while (1); | |
e2d74ac0 | 1817 | |
4ac845a2 | 1818 | return cic; |
e2d74ac0 JA |
1819 | } |
1820 | ||
4ac845a2 JA |
1821 | /* |
1822 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
1823 | * the process specific cfq io context when entered from the block layer. | |
1824 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
1825 | */ | |
febffd61 JA |
1826 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
1827 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 1828 | { |
0261d688 | 1829 | unsigned long flags; |
4ac845a2 | 1830 | int ret; |
e2d74ac0 | 1831 | |
4ac845a2 JA |
1832 | ret = radix_tree_preload(gfp_mask); |
1833 | if (!ret) { | |
1834 | cic->ioc = ioc; | |
1835 | cic->key = cfqd; | |
e2d74ac0 | 1836 | |
4ac845a2 JA |
1837 | spin_lock_irqsave(&ioc->lock, flags); |
1838 | ret = radix_tree_insert(&ioc->radix_root, | |
1839 | (unsigned long) cfqd, cic); | |
ffc4e759 JA |
1840 | if (!ret) |
1841 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
4ac845a2 | 1842 | spin_unlock_irqrestore(&ioc->lock, flags); |
e2d74ac0 | 1843 | |
4ac845a2 JA |
1844 | radix_tree_preload_end(); |
1845 | ||
1846 | if (!ret) { | |
1847 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1848 | list_add(&cic->queue_list, &cfqd->cic_list); | |
1849 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1850 | } | |
e2d74ac0 JA |
1851 | } |
1852 | ||
4ac845a2 JA |
1853 | if (ret) |
1854 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 1855 | |
4ac845a2 | 1856 | return ret; |
e2d74ac0 JA |
1857 | } |
1858 | ||
1da177e4 LT |
1859 | /* |
1860 | * Setup general io context and cfq io context. There can be several cfq | |
1861 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 1862 | * than one device managed by cfq. |
1da177e4 LT |
1863 | */ |
1864 | static struct cfq_io_context * | |
e2d74ac0 | 1865 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1866 | { |
22e2c507 | 1867 | struct io_context *ioc = NULL; |
1da177e4 | 1868 | struct cfq_io_context *cic; |
1da177e4 | 1869 | |
22e2c507 | 1870 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 1871 | |
b5deef90 | 1872 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
1873 | if (!ioc) |
1874 | return NULL; | |
1875 | ||
4ac845a2 | 1876 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
1877 | if (cic) |
1878 | goto out; | |
1da177e4 | 1879 | |
e2d74ac0 JA |
1880 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
1881 | if (cic == NULL) | |
1882 | goto err; | |
1da177e4 | 1883 | |
4ac845a2 JA |
1884 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
1885 | goto err_free; | |
1886 | ||
1da177e4 | 1887 | out: |
fc46379d JA |
1888 | smp_read_barrier_depends(); |
1889 | if (unlikely(ioc->ioprio_changed)) | |
1890 | cfq_ioc_set_ioprio(ioc); | |
1891 | ||
1da177e4 | 1892 | return cic; |
4ac845a2 JA |
1893 | err_free: |
1894 | cfq_cic_free(cic); | |
1da177e4 LT |
1895 | err: |
1896 | put_io_context(ioc); | |
1897 | return NULL; | |
1898 | } | |
1899 | ||
22e2c507 JA |
1900 | static void |
1901 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 1902 | { |
aaf1228d JA |
1903 | unsigned long elapsed = jiffies - cic->last_end_request; |
1904 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 1905 | |
22e2c507 JA |
1906 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
1907 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
1908 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
1909 | } | |
1da177e4 | 1910 | |
206dc69b | 1911 | static void |
6d048f53 JA |
1912 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, |
1913 | struct request *rq) | |
206dc69b JA |
1914 | { |
1915 | sector_t sdist; | |
1916 | u64 total; | |
1917 | ||
4d00aa47 JM |
1918 | if (!cic->last_request_pos) |
1919 | sdist = 0; | |
83096ebf TH |
1920 | else if (cic->last_request_pos < blk_rq_pos(rq)) |
1921 | sdist = blk_rq_pos(rq) - cic->last_request_pos; | |
206dc69b | 1922 | else |
83096ebf | 1923 | sdist = cic->last_request_pos - blk_rq_pos(rq); |
206dc69b JA |
1924 | |
1925 | /* | |
1926 | * Don't allow the seek distance to get too large from the | |
1927 | * odd fragment, pagein, etc | |
1928 | */ | |
1929 | if (cic->seek_samples <= 60) /* second&third seek */ | |
1930 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024); | |
1931 | else | |
1932 | sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64); | |
1933 | ||
1934 | cic->seek_samples = (7*cic->seek_samples + 256) / 8; | |
1935 | cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; | |
1936 | total = cic->seek_total + (cic->seek_samples/2); | |
1937 | do_div(total, cic->seek_samples); | |
1938 | cic->seek_mean = (sector_t)total; | |
1939 | } | |
1da177e4 | 1940 | |
22e2c507 JA |
1941 | /* |
1942 | * Disable idle window if the process thinks too long or seeks so much that | |
1943 | * it doesn't matter | |
1944 | */ | |
1945 | static void | |
1946 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1947 | struct cfq_io_context *cic) | |
1948 | { | |
7b679138 | 1949 | int old_idle, enable_idle; |
1be92f2f | 1950 | |
0871714e JA |
1951 | /* |
1952 | * Don't idle for async or idle io prio class | |
1953 | */ | |
1954 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
1955 | return; |
1956 | ||
c265a7f4 | 1957 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 1958 | |
66dac98e | 1959 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
caaa5f9f | 1960 | (cfqd->hw_tag && CIC_SEEKY(cic))) |
22e2c507 JA |
1961 | enable_idle = 0; |
1962 | else if (sample_valid(cic->ttime_samples)) { | |
1963 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
1964 | enable_idle = 0; | |
1965 | else | |
1966 | enable_idle = 1; | |
1da177e4 LT |
1967 | } |
1968 | ||
7b679138 JA |
1969 | if (old_idle != enable_idle) { |
1970 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
1971 | if (enable_idle) | |
1972 | cfq_mark_cfqq_idle_window(cfqq); | |
1973 | else | |
1974 | cfq_clear_cfqq_idle_window(cfqq); | |
1975 | } | |
22e2c507 | 1976 | } |
1da177e4 | 1977 | |
22e2c507 JA |
1978 | /* |
1979 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
1980 | * no or if we aren't sure, a 1 will cause a preempt. | |
1981 | */ | |
1982 | static int | |
1983 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
5e705374 | 1984 | struct request *rq) |
22e2c507 | 1985 | { |
6d048f53 | 1986 | struct cfq_queue *cfqq; |
22e2c507 | 1987 | |
6d048f53 JA |
1988 | cfqq = cfqd->active_queue; |
1989 | if (!cfqq) | |
22e2c507 JA |
1990 | return 0; |
1991 | ||
6d048f53 JA |
1992 | if (cfq_slice_used(cfqq)) |
1993 | return 1; | |
1994 | ||
1995 | if (cfq_class_idle(new_cfqq)) | |
caaa5f9f | 1996 | return 0; |
22e2c507 JA |
1997 | |
1998 | if (cfq_class_idle(cfqq)) | |
1999 | return 1; | |
1e3335de | 2000 | |
374f84ac JA |
2001 | /* |
2002 | * if the new request is sync, but the currently running queue is | |
2003 | * not, let the sync request have priority. | |
2004 | */ | |
5e705374 | 2005 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
22e2c507 | 2006 | return 1; |
1e3335de | 2007 | |
374f84ac JA |
2008 | /* |
2009 | * So both queues are sync. Let the new request get disk time if | |
2010 | * it's a metadata request and the current queue is doing regular IO. | |
2011 | */ | |
2012 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
2013 | return 1; | |
22e2c507 | 2014 | |
3a9a3f6c DS |
2015 | /* |
2016 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
2017 | */ | |
2018 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
2019 | return 1; | |
2020 | ||
1e3335de JA |
2021 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
2022 | return 0; | |
2023 | ||
2024 | /* | |
2025 | * if this request is as-good as one we would expect from the | |
2026 | * current cfqq, let it preempt | |
2027 | */ | |
6d048f53 | 2028 | if (cfq_rq_close(cfqd, rq)) |
1e3335de JA |
2029 | return 1; |
2030 | ||
22e2c507 JA |
2031 | return 0; |
2032 | } | |
2033 | ||
2034 | /* | |
2035 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
2036 | * let it have half of its nominal slice. | |
2037 | */ | |
2038 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2039 | { | |
7b679138 | 2040 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
6084cdda | 2041 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 2042 | |
bf572256 JA |
2043 | /* |
2044 | * Put the new queue at the front of the of the current list, | |
2045 | * so we know that it will be selected next. | |
2046 | */ | |
2047 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
2048 | |
2049 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 2050 | |
44f7c160 JA |
2051 | cfqq->slice_end = 0; |
2052 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
2053 | } |
2054 | ||
22e2c507 | 2055 | /* |
5e705374 | 2056 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
2057 | * something we should do about it |
2058 | */ | |
2059 | static void | |
5e705374 JA |
2060 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2061 | struct request *rq) | |
22e2c507 | 2062 | { |
5e705374 | 2063 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 2064 | |
45333d5a | 2065 | cfqd->rq_queued++; |
374f84ac JA |
2066 | if (rq_is_meta(rq)) |
2067 | cfqq->meta_pending++; | |
2068 | ||
9c2c38a1 | 2069 | cfq_update_io_thinktime(cfqd, cic); |
6d048f53 | 2070 | cfq_update_io_seektime(cfqd, cic, rq); |
9c2c38a1 JA |
2071 | cfq_update_idle_window(cfqd, cfqq, cic); |
2072 | ||
83096ebf | 2073 | cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
22e2c507 JA |
2074 | |
2075 | if (cfqq == cfqd->active_queue) { | |
2076 | /* | |
b029195d JA |
2077 | * Remember that we saw a request from this process, but |
2078 | * don't start queuing just yet. Otherwise we risk seeing lots | |
2079 | * of tiny requests, because we disrupt the normal plugging | |
d6ceb25e JA |
2080 | * and merging. If the request is already larger than a single |
2081 | * page, let it rip immediately. For that case we assume that | |
2d870722 JA |
2082 | * merging is already done. Ditto for a busy system that |
2083 | * has other work pending, don't risk delaying until the | |
2084 | * idle timer unplug to continue working. | |
22e2c507 | 2085 | */ |
d6ceb25e | 2086 | if (cfq_cfqq_wait_request(cfqq)) { |
2d870722 JA |
2087 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
2088 | cfqd->busy_queues > 1) { | |
d6ceb25e | 2089 | del_timer(&cfqd->idle_slice_timer); |
a7f55792 | 2090 | __blk_run_queue(cfqd->queue); |
d6ceb25e | 2091 | } |
b029195d | 2092 | cfq_mark_cfqq_must_dispatch(cfqq); |
d6ceb25e | 2093 | } |
5e705374 | 2094 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
2095 | /* |
2096 | * not the active queue - expire current slice if it is | |
2097 | * idle and has expired it's mean thinktime or this new queue | |
3a9a3f6c DS |
2098 | * has some old slice time left and is of higher priority or |
2099 | * this new queue is RT and the current one is BE | |
22e2c507 JA |
2100 | */ |
2101 | cfq_preempt_queue(cfqd, cfqq); | |
a7f55792 | 2102 | __blk_run_queue(cfqd->queue); |
22e2c507 | 2103 | } |
1da177e4 LT |
2104 | } |
2105 | ||
165125e1 | 2106 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2107 | { |
b4878f24 | 2108 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 2109 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 2110 | |
7b679138 | 2111 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
fd0928df | 2112 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 2113 | |
5e705374 | 2114 | cfq_add_rq_rb(rq); |
1da177e4 | 2115 | |
22e2c507 JA |
2116 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
2117 | ||
5e705374 | 2118 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
2119 | } |
2120 | ||
45333d5a AC |
2121 | /* |
2122 | * Update hw_tag based on peak queue depth over 50 samples under | |
2123 | * sufficient load. | |
2124 | */ | |
2125 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
2126 | { | |
2127 | if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak) | |
2128 | cfqd->rq_in_driver_peak = cfqd->rq_in_driver; | |
2129 | ||
2130 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
2131 | cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) | |
2132 | return; | |
2133 | ||
2134 | if (cfqd->hw_tag_samples++ < 50) | |
2135 | return; | |
2136 | ||
2137 | if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN) | |
2138 | cfqd->hw_tag = 1; | |
2139 | else | |
2140 | cfqd->hw_tag = 0; | |
2141 | ||
2142 | cfqd->hw_tag_samples = 0; | |
2143 | cfqd->rq_in_driver_peak = 0; | |
2144 | } | |
2145 | ||
165125e1 | 2146 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2147 | { |
5e705374 | 2148 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 2149 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 2150 | const int sync = rq_is_sync(rq); |
b4878f24 | 2151 | unsigned long now; |
1da177e4 | 2152 | |
b4878f24 | 2153 | now = jiffies; |
7b679138 | 2154 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
1da177e4 | 2155 | |
45333d5a AC |
2156 | cfq_update_hw_tag(cfqd); |
2157 | ||
b4878f24 | 2158 | WARN_ON(!cfqd->rq_in_driver); |
6d048f53 | 2159 | WARN_ON(!cfqq->dispatched); |
b4878f24 | 2160 | cfqd->rq_in_driver--; |
6d048f53 | 2161 | cfqq->dispatched--; |
1da177e4 | 2162 | |
3ed9a296 JA |
2163 | if (cfq_cfqq_sync(cfqq)) |
2164 | cfqd->sync_flight--; | |
2165 | ||
caaa5f9f | 2166 | if (sync) |
5e705374 | 2167 | RQ_CIC(rq)->last_end_request = now; |
caaa5f9f JA |
2168 | |
2169 | /* | |
2170 | * If this is the active queue, check if it needs to be expired, | |
2171 | * or if we want to idle in case it has no pending requests. | |
2172 | */ | |
2173 | if (cfqd->active_queue == cfqq) { | |
a36e71f9 JA |
2174 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
2175 | ||
44f7c160 JA |
2176 | if (cfq_cfqq_slice_new(cfqq)) { |
2177 | cfq_set_prio_slice(cfqd, cfqq); | |
2178 | cfq_clear_cfqq_slice_new(cfqq); | |
2179 | } | |
a36e71f9 JA |
2180 | /* |
2181 | * If there are no requests waiting in this queue, and | |
2182 | * there are other queues ready to issue requests, AND | |
2183 | * those other queues are issuing requests within our | |
2184 | * mean seek distance, give them a chance to run instead | |
2185 | * of idling. | |
2186 | */ | |
0871714e | 2187 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 2188 | cfq_slice_expired(cfqd, 1); |
a36e71f9 JA |
2189 | else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) && |
2190 | sync && !rq_noidle(rq)) | |
6d048f53 | 2191 | cfq_arm_slice_timer(cfqd); |
caaa5f9f | 2192 | } |
6d048f53 JA |
2193 | |
2194 | if (!cfqd->rq_in_driver) | |
2195 | cfq_schedule_dispatch(cfqd); | |
1da177e4 LT |
2196 | } |
2197 | ||
22e2c507 JA |
2198 | /* |
2199 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
2200 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
2201 | */ | |
2202 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 2203 | { |
22e2c507 JA |
2204 | if (has_fs_excl()) { |
2205 | /* | |
2206 | * boost idle prio on transactions that would lock out other | |
2207 | * users of the filesystem | |
2208 | */ | |
2209 | if (cfq_class_idle(cfqq)) | |
2210 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2211 | if (cfqq->ioprio > IOPRIO_NORM) | |
2212 | cfqq->ioprio = IOPRIO_NORM; | |
2213 | } else { | |
2214 | /* | |
2215 | * check if we need to unboost the queue | |
2216 | */ | |
2217 | if (cfqq->ioprio_class != cfqq->org_ioprio_class) | |
2218 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
2219 | if (cfqq->ioprio != cfqq->org_ioprio) | |
2220 | cfqq->ioprio = cfqq->org_ioprio; | |
2221 | } | |
22e2c507 | 2222 | } |
1da177e4 | 2223 | |
89850f7e | 2224 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 2225 | { |
3b18152c | 2226 | if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && |
99f95e52 | 2227 | !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 2228 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 2229 | return ELV_MQUEUE_MUST; |
3b18152c | 2230 | } |
1da177e4 | 2231 | |
22e2c507 | 2232 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
2233 | } |
2234 | ||
165125e1 | 2235 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
2236 | { |
2237 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2238 | struct task_struct *tsk = current; | |
91fac317 | 2239 | struct cfq_io_context *cic; |
22e2c507 JA |
2240 | struct cfq_queue *cfqq; |
2241 | ||
2242 | /* | |
2243 | * don't force setup of a queue from here, as a call to may_queue | |
2244 | * does not necessarily imply that a request actually will be queued. | |
2245 | * so just lookup a possibly existing queue, or return 'may queue' | |
2246 | * if that fails | |
2247 | */ | |
4ac845a2 | 2248 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
2249 | if (!cic) |
2250 | return ELV_MQUEUE_MAY; | |
2251 | ||
b0b78f81 | 2252 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
22e2c507 | 2253 | if (cfqq) { |
fd0928df | 2254 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
2255 | cfq_prio_boost(cfqq); |
2256 | ||
89850f7e | 2257 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
2258 | } |
2259 | ||
2260 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
2261 | } |
2262 | ||
1da177e4 LT |
2263 | /* |
2264 | * queue lock held here | |
2265 | */ | |
bb37b94c | 2266 | static void cfq_put_request(struct request *rq) |
1da177e4 | 2267 | { |
5e705374 | 2268 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 2269 | |
5e705374 | 2270 | if (cfqq) { |
22e2c507 | 2271 | const int rw = rq_data_dir(rq); |
1da177e4 | 2272 | |
22e2c507 JA |
2273 | BUG_ON(!cfqq->allocated[rw]); |
2274 | cfqq->allocated[rw]--; | |
1da177e4 | 2275 | |
5e705374 | 2276 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 2277 | |
1da177e4 | 2278 | rq->elevator_private = NULL; |
5e705374 | 2279 | rq->elevator_private2 = NULL; |
1da177e4 | 2280 | |
1da177e4 LT |
2281 | cfq_put_queue(cfqq); |
2282 | } | |
2283 | } | |
2284 | ||
2285 | /* | |
22e2c507 | 2286 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2287 | */ |
22e2c507 | 2288 | static int |
165125e1 | 2289 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
2290 | { |
2291 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2292 | struct cfq_io_context *cic; | |
2293 | const int rw = rq_data_dir(rq); | |
7749a8d4 | 2294 | const int is_sync = rq_is_sync(rq); |
22e2c507 | 2295 | struct cfq_queue *cfqq; |
1da177e4 LT |
2296 | unsigned long flags; |
2297 | ||
2298 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2299 | ||
e2d74ac0 | 2300 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2301 | |
1da177e4 LT |
2302 | spin_lock_irqsave(q->queue_lock, flags); |
2303 | ||
22e2c507 JA |
2304 | if (!cic) |
2305 | goto queue_fail; | |
2306 | ||
91fac317 VT |
2307 | cfqq = cic_to_cfqq(cic, is_sync); |
2308 | if (!cfqq) { | |
fd0928df | 2309 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 2310 | |
22e2c507 JA |
2311 | if (!cfqq) |
2312 | goto queue_fail; | |
1da177e4 | 2313 | |
91fac317 VT |
2314 | cic_set_cfqq(cic, cfqq, is_sync); |
2315 | } | |
1da177e4 LT |
2316 | |
2317 | cfqq->allocated[rw]++; | |
3b18152c | 2318 | cfq_clear_cfqq_must_alloc(cfqq); |
22e2c507 | 2319 | atomic_inc(&cfqq->ref); |
1da177e4 | 2320 | |
5e705374 | 2321 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 2322 | |
5e705374 JA |
2323 | rq->elevator_private = cic; |
2324 | rq->elevator_private2 = cfqq; | |
2325 | return 0; | |
1da177e4 | 2326 | |
22e2c507 JA |
2327 | queue_fail: |
2328 | if (cic) | |
2329 | put_io_context(cic->ioc); | |
89850f7e | 2330 | |
3b18152c | 2331 | cfq_schedule_dispatch(cfqd); |
1da177e4 | 2332 | spin_unlock_irqrestore(q->queue_lock, flags); |
7b679138 | 2333 | cfq_log(cfqd, "set_request fail"); |
1da177e4 LT |
2334 | return 1; |
2335 | } | |
2336 | ||
65f27f38 | 2337 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 2338 | { |
65f27f38 DH |
2339 | struct cfq_data *cfqd = |
2340 | container_of(work, struct cfq_data, unplug_work); | |
165125e1 | 2341 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2342 | |
40bb54d1 | 2343 | spin_lock_irq(q->queue_lock); |
a7f55792 | 2344 | __blk_run_queue(cfqd->queue); |
40bb54d1 | 2345 | spin_unlock_irq(q->queue_lock); |
22e2c507 JA |
2346 | } |
2347 | ||
2348 | /* | |
2349 | * Timer running if the active_queue is currently idling inside its time slice | |
2350 | */ | |
2351 | static void cfq_idle_slice_timer(unsigned long data) | |
2352 | { | |
2353 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2354 | struct cfq_queue *cfqq; | |
2355 | unsigned long flags; | |
3c6bd2f8 | 2356 | int timed_out = 1; |
22e2c507 | 2357 | |
7b679138 JA |
2358 | cfq_log(cfqd, "idle timer fired"); |
2359 | ||
22e2c507 JA |
2360 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2361 | ||
fe094d98 JA |
2362 | cfqq = cfqd->active_queue; |
2363 | if (cfqq) { | |
3c6bd2f8 JA |
2364 | timed_out = 0; |
2365 | ||
b029195d JA |
2366 | /* |
2367 | * We saw a request before the queue expired, let it through | |
2368 | */ | |
2369 | if (cfq_cfqq_must_dispatch(cfqq)) | |
2370 | goto out_kick; | |
2371 | ||
22e2c507 JA |
2372 | /* |
2373 | * expired | |
2374 | */ | |
44f7c160 | 2375 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2376 | goto expire; |
2377 | ||
2378 | /* | |
2379 | * only expire and reinvoke request handler, if there are | |
2380 | * other queues with pending requests | |
2381 | */ | |
caaa5f9f | 2382 | if (!cfqd->busy_queues) |
22e2c507 | 2383 | goto out_cont; |
22e2c507 JA |
2384 | |
2385 | /* | |
2386 | * not expired and it has a request pending, let it dispatch | |
2387 | */ | |
75e50984 | 2388 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 2389 | goto out_kick; |
22e2c507 JA |
2390 | } |
2391 | expire: | |
6084cdda | 2392 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2393 | out_kick: |
3b18152c | 2394 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2395 | out_cont: |
2396 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2397 | } | |
2398 | ||
3b18152c JA |
2399 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2400 | { | |
2401 | del_timer_sync(&cfqd->idle_slice_timer); | |
64d01dc9 | 2402 | cancel_work_sync(&cfqd->unplug_work); |
3b18152c | 2403 | } |
22e2c507 | 2404 | |
c2dea2d1 VT |
2405 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2406 | { | |
2407 | int i; | |
2408 | ||
2409 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2410 | if (cfqd->async_cfqq[0][i]) | |
2411 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2412 | if (cfqd->async_cfqq[1][i]) | |
2413 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
c2dea2d1 | 2414 | } |
2389d1ef ON |
2415 | |
2416 | if (cfqd->async_idle_cfqq) | |
2417 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2418 | } |
2419 | ||
b374d18a | 2420 | static void cfq_exit_queue(struct elevator_queue *e) |
1da177e4 | 2421 | { |
22e2c507 | 2422 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2423 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2424 | |
3b18152c | 2425 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2426 | |
d9ff4187 | 2427 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2428 | |
d9ff4187 | 2429 | if (cfqd->active_queue) |
6084cdda | 2430 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2431 | |
2432 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2433 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2434 | struct cfq_io_context, | |
2435 | queue_list); | |
89850f7e JA |
2436 | |
2437 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2438 | } |
e2d74ac0 | 2439 | |
c2dea2d1 | 2440 | cfq_put_async_queues(cfqd); |
15c31be4 | 2441 | |
d9ff4187 | 2442 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2443 | |
2444 | cfq_shutdown_timer_wq(cfqd); | |
2445 | ||
a90d742e | 2446 | kfree(cfqd); |
1da177e4 LT |
2447 | } |
2448 | ||
165125e1 | 2449 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2450 | { |
2451 | struct cfq_data *cfqd; | |
26a2ac00 | 2452 | int i; |
1da177e4 | 2453 | |
94f6030c | 2454 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2455 | if (!cfqd) |
bc1c1169 | 2456 | return NULL; |
1da177e4 | 2457 | |
cc09e299 | 2458 | cfqd->service_tree = CFQ_RB_ROOT; |
26a2ac00 JA |
2459 | |
2460 | /* | |
2461 | * Not strictly needed (since RB_ROOT just clears the node and we | |
2462 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
2463 | * to add magic to the rb code | |
2464 | */ | |
2465 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2466 | cfqd->prio_trees[i] = RB_ROOT; | |
2467 | ||
d9ff4187 | 2468 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2469 | |
1da177e4 | 2470 | cfqd->queue = q; |
1da177e4 | 2471 | |
22e2c507 JA |
2472 | init_timer(&cfqd->idle_slice_timer); |
2473 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2474 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2475 | ||
65f27f38 | 2476 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2477 | |
1da177e4 | 2478 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2479 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2480 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2481 | cfqd->cfq_back_max = cfq_back_max; |
2482 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2483 | cfqd->cfq_slice[0] = cfq_slice_async; |
2484 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2485 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2486 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
45333d5a | 2487 | cfqd->hw_tag = 1; |
3b18152c | 2488 | |
bc1c1169 | 2489 | return cfqd; |
1da177e4 LT |
2490 | } |
2491 | ||
2492 | static void cfq_slab_kill(void) | |
2493 | { | |
d6de8be7 JA |
2494 | /* |
2495 | * Caller already ensured that pending RCU callbacks are completed, | |
2496 | * so we should have no busy allocations at this point. | |
2497 | */ | |
1da177e4 LT |
2498 | if (cfq_pool) |
2499 | kmem_cache_destroy(cfq_pool); | |
2500 | if (cfq_ioc_pool) | |
2501 | kmem_cache_destroy(cfq_ioc_pool); | |
2502 | } | |
2503 | ||
2504 | static int __init cfq_slab_setup(void) | |
2505 | { | |
0a31bd5f | 2506 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
2507 | if (!cfq_pool) |
2508 | goto fail; | |
2509 | ||
34e6bbf2 | 2510 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
2511 | if (!cfq_ioc_pool) |
2512 | goto fail; | |
2513 | ||
2514 | return 0; | |
2515 | fail: | |
2516 | cfq_slab_kill(); | |
2517 | return -ENOMEM; | |
2518 | } | |
2519 | ||
1da177e4 LT |
2520 | /* |
2521 | * sysfs parts below --> | |
2522 | */ | |
1da177e4 LT |
2523 | static ssize_t |
2524 | cfq_var_show(unsigned int var, char *page) | |
2525 | { | |
2526 | return sprintf(page, "%d\n", var); | |
2527 | } | |
2528 | ||
2529 | static ssize_t | |
2530 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
2531 | { | |
2532 | char *p = (char *) page; | |
2533 | ||
2534 | *var = simple_strtoul(p, &p, 10); | |
2535 | return count; | |
2536 | } | |
2537 | ||
1da177e4 | 2538 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
b374d18a | 2539 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
1da177e4 | 2540 | { \ |
3d1ab40f | 2541 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2542 | unsigned int __data = __VAR; \ |
2543 | if (__CONV) \ | |
2544 | __data = jiffies_to_msecs(__data); \ | |
2545 | return cfq_var_show(__data, (page)); \ | |
2546 | } | |
2547 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
2548 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
2549 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
2550 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
2551 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
2552 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
2553 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
2554 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
2555 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
1da177e4 LT |
2556 | #undef SHOW_FUNCTION |
2557 | ||
2558 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
b374d18a | 2559 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
1da177e4 | 2560 | { \ |
3d1ab40f | 2561 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
2562 | unsigned int __data; \ |
2563 | int ret = cfq_var_store(&__data, (page), count); \ | |
2564 | if (__data < (MIN)) \ | |
2565 | __data = (MIN); \ | |
2566 | else if (__data > (MAX)) \ | |
2567 | __data = (MAX); \ | |
2568 | if (__CONV) \ | |
2569 | *(__PTR) = msecs_to_jiffies(__data); \ | |
2570 | else \ | |
2571 | *(__PTR) = __data; \ | |
2572 | return ret; \ | |
2573 | } | |
2574 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
fe094d98 JA |
2575 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
2576 | UINT_MAX, 1); | |
2577 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
2578 | UINT_MAX, 1); | |
e572ec7e | 2579 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
fe094d98 JA |
2580 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
2581 | UINT_MAX, 0); | |
22e2c507 JA |
2582 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
2583 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
2584 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
fe094d98 JA |
2585 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
2586 | UINT_MAX, 0); | |
1da177e4 LT |
2587 | #undef STORE_FUNCTION |
2588 | ||
e572ec7e AV |
2589 | #define CFQ_ATTR(name) \ |
2590 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
2591 | ||
2592 | static struct elv_fs_entry cfq_attrs[] = { | |
2593 | CFQ_ATTR(quantum), | |
e572ec7e AV |
2594 | CFQ_ATTR(fifo_expire_sync), |
2595 | CFQ_ATTR(fifo_expire_async), | |
2596 | CFQ_ATTR(back_seek_max), | |
2597 | CFQ_ATTR(back_seek_penalty), | |
2598 | CFQ_ATTR(slice_sync), | |
2599 | CFQ_ATTR(slice_async), | |
2600 | CFQ_ATTR(slice_async_rq), | |
2601 | CFQ_ATTR(slice_idle), | |
e572ec7e | 2602 | __ATTR_NULL |
1da177e4 LT |
2603 | }; |
2604 | ||
1da177e4 LT |
2605 | static struct elevator_type iosched_cfq = { |
2606 | .ops = { | |
2607 | .elevator_merge_fn = cfq_merge, | |
2608 | .elevator_merged_fn = cfq_merged_request, | |
2609 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 2610 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 2611 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 2612 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 2613 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
2614 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
2615 | .elevator_queue_empty_fn = cfq_queue_empty, | |
2616 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
2617 | .elevator_former_req_fn = elv_rb_former_request, |
2618 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
2619 | .elevator_set_req_fn = cfq_set_request, |
2620 | .elevator_put_req_fn = cfq_put_request, | |
2621 | .elevator_may_queue_fn = cfq_may_queue, | |
2622 | .elevator_init_fn = cfq_init_queue, | |
2623 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 2624 | .trim = cfq_free_io_context, |
1da177e4 | 2625 | }, |
3d1ab40f | 2626 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
2627 | .elevator_name = "cfq", |
2628 | .elevator_owner = THIS_MODULE, | |
2629 | }; | |
2630 | ||
2631 | static int __init cfq_init(void) | |
2632 | { | |
22e2c507 JA |
2633 | /* |
2634 | * could be 0 on HZ < 1000 setups | |
2635 | */ | |
2636 | if (!cfq_slice_async) | |
2637 | cfq_slice_async = 1; | |
2638 | if (!cfq_slice_idle) | |
2639 | cfq_slice_idle = 1; | |
2640 | ||
1da177e4 LT |
2641 | if (cfq_slab_setup()) |
2642 | return -ENOMEM; | |
2643 | ||
2fdd82bd | 2644 | elv_register(&iosched_cfq); |
1da177e4 | 2645 | |
2fdd82bd | 2646 | return 0; |
1da177e4 LT |
2647 | } |
2648 | ||
2649 | static void __exit cfq_exit(void) | |
2650 | { | |
6e9a4738 | 2651 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 2652 | elv_unregister(&iosched_cfq); |
334e94de | 2653 | ioc_gone = &all_gone; |
fba82272 OH |
2654 | /* ioc_gone's update must be visible before reading ioc_count */ |
2655 | smp_wmb(); | |
d6de8be7 JA |
2656 | |
2657 | /* | |
2658 | * this also protects us from entering cfq_slab_kill() with | |
2659 | * pending RCU callbacks | |
2660 | */ | |
4050cf16 | 2661 | if (elv_ioc_count_read(ioc_count)) |
9a11b4ed | 2662 | wait_for_completion(&all_gone); |
83521d3e | 2663 | cfq_slab_kill(); |
1da177e4 LT |
2664 | } |
2665 | ||
2666 | module_init(cfq_init); | |
2667 | module_exit(cfq_exit); | |
2668 | ||
2669 | MODULE_AUTHOR("Jens Axboe"); | |
2670 | MODULE_LICENSE("GPL"); | |
2671 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |