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