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