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1da177e4 LT |
1 | /* |
2 | * linux/drivers/block/as-iosched.c | |
3 | * | |
4 | * Anticipatory & deadline i/o scheduler. | |
5 | * | |
6 | * Copyright (C) 2002 Jens Axboe <axboe@suse.de> | |
7 | * Nick Piggin <piggin@cyberone.com.au> | |
8 | * | |
9 | */ | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/fs.h> | |
12 | #include <linux/blkdev.h> | |
13 | #include <linux/elevator.h> | |
14 | #include <linux/bio.h> | |
15 | #include <linux/config.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/slab.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/compiler.h> | |
20 | #include <linux/hash.h> | |
21 | #include <linux/rbtree.h> | |
22 | #include <linux/interrupt.h> | |
23 | ||
24 | #define REQ_SYNC 1 | |
25 | #define REQ_ASYNC 0 | |
26 | ||
27 | /* | |
28 | * See Documentation/block/as-iosched.txt | |
29 | */ | |
30 | ||
31 | /* | |
32 | * max time before a read is submitted. | |
33 | */ | |
34 | #define default_read_expire (HZ / 8) | |
35 | ||
36 | /* | |
37 | * ditto for writes, these limits are not hard, even | |
38 | * if the disk is capable of satisfying them. | |
39 | */ | |
40 | #define default_write_expire (HZ / 4) | |
41 | ||
42 | /* | |
43 | * read_batch_expire describes how long we will allow a stream of reads to | |
44 | * persist before looking to see whether it is time to switch over to writes. | |
45 | */ | |
46 | #define default_read_batch_expire (HZ / 2) | |
47 | ||
48 | /* | |
49 | * write_batch_expire describes how long we want a stream of writes to run for. | |
50 | * This is not a hard limit, but a target we set for the auto-tuning thingy. | |
51 | * See, the problem is: we can send a lot of writes to disk cache / TCQ in | |
52 | * a short amount of time... | |
53 | */ | |
54 | #define default_write_batch_expire (HZ / 8) | |
55 | ||
56 | /* | |
57 | * max time we may wait to anticipate a read (default around 6ms) | |
58 | */ | |
59 | #define default_antic_expire ((HZ / 150) ? HZ / 150 : 1) | |
60 | ||
61 | /* | |
62 | * Keep track of up to 20ms thinktimes. We can go as big as we like here, | |
63 | * however huge values tend to interfere and not decay fast enough. A program | |
64 | * might be in a non-io phase of operation. Waiting on user input for example, | |
65 | * or doing a lengthy computation. A small penalty can be justified there, and | |
66 | * will still catch out those processes that constantly have large thinktimes. | |
67 | */ | |
68 | #define MAX_THINKTIME (HZ/50UL) | |
69 | ||
70 | /* Bits in as_io_context.state */ | |
71 | enum as_io_states { | |
72 | AS_TASK_RUNNING=0, /* Process has not exitted */ | |
73 | AS_TASK_IOSTARTED, /* Process has started some IO */ | |
74 | AS_TASK_IORUNNING, /* Process has completed some IO */ | |
75 | }; | |
76 | ||
77 | enum anticipation_status { | |
78 | ANTIC_OFF=0, /* Not anticipating (normal operation) */ | |
79 | ANTIC_WAIT_REQ, /* The last read has not yet completed */ | |
80 | ANTIC_WAIT_NEXT, /* Currently anticipating a request vs | |
81 | last read (which has completed) */ | |
82 | ANTIC_FINISHED, /* Anticipating but have found a candidate | |
83 | * or timed out */ | |
84 | }; | |
85 | ||
86 | struct as_data { | |
87 | /* | |
88 | * run time data | |
89 | */ | |
90 | ||
91 | struct request_queue *q; /* the "owner" queue */ | |
92 | ||
93 | /* | |
94 | * requests (as_rq s) are present on both sort_list and fifo_list | |
95 | */ | |
96 | struct rb_root sort_list[2]; | |
97 | struct list_head fifo_list[2]; | |
98 | ||
99 | struct as_rq *next_arq[2]; /* next in sort order */ | |
100 | sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */ | |
1da177e4 LT |
101 | struct list_head *hash; /* request hash */ |
102 | ||
103 | unsigned long exit_prob; /* probability a task will exit while | |
104 | being waited on */ | |
105 | unsigned long new_ttime_total; /* mean thinktime on new proc */ | |
106 | unsigned long new_ttime_mean; | |
107 | u64 new_seek_total; /* mean seek on new proc */ | |
108 | sector_t new_seek_mean; | |
109 | ||
110 | unsigned long current_batch_expires; | |
111 | unsigned long last_check_fifo[2]; | |
112 | int changed_batch; /* 1: waiting for old batch to end */ | |
113 | int new_batch; /* 1: waiting on first read complete */ | |
114 | int batch_data_dir; /* current batch REQ_SYNC / REQ_ASYNC */ | |
115 | int write_batch_count; /* max # of reqs in a write batch */ | |
116 | int current_write_count; /* how many requests left this batch */ | |
117 | int write_batch_idled; /* has the write batch gone idle? */ | |
118 | mempool_t *arq_pool; | |
119 | ||
120 | enum anticipation_status antic_status; | |
121 | unsigned long antic_start; /* jiffies: when it started */ | |
122 | struct timer_list antic_timer; /* anticipatory scheduling timer */ | |
123 | struct work_struct antic_work; /* Deferred unplugging */ | |
124 | struct io_context *io_context; /* Identify the expected process */ | |
125 | int ioc_finished; /* IO associated with io_context is finished */ | |
126 | int nr_dispatched; | |
127 | ||
128 | /* | |
129 | * settings that change how the i/o scheduler behaves | |
130 | */ | |
131 | unsigned long fifo_expire[2]; | |
132 | unsigned long batch_expire[2]; | |
133 | unsigned long antic_expire; | |
134 | }; | |
135 | ||
136 | #define list_entry_fifo(ptr) list_entry((ptr), struct as_rq, fifo) | |
137 | ||
138 | /* | |
139 | * per-request data. | |
140 | */ | |
141 | enum arq_state { | |
142 | AS_RQ_NEW=0, /* New - not referenced and not on any lists */ | |
143 | AS_RQ_QUEUED, /* In the request queue. It belongs to the | |
144 | scheduler */ | |
145 | AS_RQ_DISPATCHED, /* On the dispatch list. It belongs to the | |
146 | driver now */ | |
147 | AS_RQ_PRESCHED, /* Debug poisoning for requests being used */ | |
148 | AS_RQ_REMOVED, | |
149 | AS_RQ_MERGED, | |
150 | AS_RQ_POSTSCHED, /* when they shouldn't be */ | |
151 | }; | |
152 | ||
153 | struct as_rq { | |
154 | /* | |
155 | * rbtree index, key is the starting offset | |
156 | */ | |
157 | struct rb_node rb_node; | |
158 | sector_t rb_key; | |
159 | ||
160 | struct request *request; | |
161 | ||
162 | struct io_context *io_context; /* The submitting task */ | |
163 | ||
164 | /* | |
165 | * request hash, key is the ending offset (for back merge lookup) | |
166 | */ | |
167 | struct list_head hash; | |
168 | unsigned int on_hash; | |
169 | ||
170 | /* | |
171 | * expire fifo | |
172 | */ | |
173 | struct list_head fifo; | |
174 | unsigned long expires; | |
175 | ||
176 | unsigned int is_sync; | |
177 | enum arq_state state; | |
178 | }; | |
179 | ||
180 | #define RQ_DATA(rq) ((struct as_rq *) (rq)->elevator_private) | |
181 | ||
182 | static kmem_cache_t *arq_pool; | |
183 | ||
184 | /* | |
185 | * IO Context helper functions | |
186 | */ | |
187 | ||
188 | /* Called to deallocate the as_io_context */ | |
189 | static void free_as_io_context(struct as_io_context *aic) | |
190 | { | |
191 | kfree(aic); | |
192 | } | |
193 | ||
194 | /* Called when the task exits */ | |
195 | static void exit_as_io_context(struct as_io_context *aic) | |
196 | { | |
197 | WARN_ON(!test_bit(AS_TASK_RUNNING, &aic->state)); | |
198 | clear_bit(AS_TASK_RUNNING, &aic->state); | |
199 | } | |
200 | ||
201 | static struct as_io_context *alloc_as_io_context(void) | |
202 | { | |
203 | struct as_io_context *ret; | |
204 | ||
205 | ret = kmalloc(sizeof(*ret), GFP_ATOMIC); | |
206 | if (ret) { | |
207 | ret->dtor = free_as_io_context; | |
208 | ret->exit = exit_as_io_context; | |
209 | ret->state = 1 << AS_TASK_RUNNING; | |
210 | atomic_set(&ret->nr_queued, 0); | |
211 | atomic_set(&ret->nr_dispatched, 0); | |
212 | spin_lock_init(&ret->lock); | |
213 | ret->ttime_total = 0; | |
214 | ret->ttime_samples = 0; | |
215 | ret->ttime_mean = 0; | |
216 | ret->seek_total = 0; | |
217 | ret->seek_samples = 0; | |
218 | ret->seek_mean = 0; | |
219 | } | |
220 | ||
221 | return ret; | |
222 | } | |
223 | ||
224 | /* | |
225 | * If the current task has no AS IO context then create one and initialise it. | |
226 | * Then take a ref on the task's io context and return it. | |
227 | */ | |
228 | static struct io_context *as_get_io_context(void) | |
229 | { | |
230 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
231 | if (ioc && !ioc->aic) { | |
232 | ioc->aic = alloc_as_io_context(); | |
233 | if (!ioc->aic) { | |
234 | put_io_context(ioc); | |
235 | ioc = NULL; | |
236 | } | |
237 | } | |
238 | return ioc; | |
239 | } | |
240 | ||
b4878f24 JA |
241 | static void as_put_io_context(struct as_rq *arq) |
242 | { | |
243 | struct as_io_context *aic; | |
244 | ||
245 | if (unlikely(!arq->io_context)) | |
246 | return; | |
247 | ||
248 | aic = arq->io_context->aic; | |
249 | ||
250 | if (arq->is_sync == REQ_SYNC && aic) { | |
251 | spin_lock(&aic->lock); | |
252 | set_bit(AS_TASK_IORUNNING, &aic->state); | |
253 | aic->last_end_request = jiffies; | |
254 | spin_unlock(&aic->lock); | |
255 | } | |
256 | ||
257 | put_io_context(arq->io_context); | |
258 | } | |
259 | ||
1da177e4 LT |
260 | /* |
261 | * the back merge hash support functions | |
262 | */ | |
263 | static const int as_hash_shift = 6; | |
264 | #define AS_HASH_BLOCK(sec) ((sec) >> 3) | |
265 | #define AS_HASH_FN(sec) (hash_long(AS_HASH_BLOCK((sec)), as_hash_shift)) | |
266 | #define AS_HASH_ENTRIES (1 << as_hash_shift) | |
267 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
268 | #define list_entry_hash(ptr) list_entry((ptr), struct as_rq, hash) | |
269 | ||
270 | static inline void __as_del_arq_hash(struct as_rq *arq) | |
271 | { | |
272 | arq->on_hash = 0; | |
273 | list_del_init(&arq->hash); | |
274 | } | |
275 | ||
276 | static inline void as_del_arq_hash(struct as_rq *arq) | |
277 | { | |
278 | if (arq->on_hash) | |
279 | __as_del_arq_hash(arq); | |
280 | } | |
281 | ||
1da177e4 LT |
282 | static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq) |
283 | { | |
284 | struct request *rq = arq->request; | |
285 | ||
286 | BUG_ON(arq->on_hash); | |
287 | ||
288 | arq->on_hash = 1; | |
289 | list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]); | |
290 | } | |
291 | ||
292 | /* | |
293 | * move hot entry to front of chain | |
294 | */ | |
295 | static inline void as_hot_arq_hash(struct as_data *ad, struct as_rq *arq) | |
296 | { | |
297 | struct request *rq = arq->request; | |
298 | struct list_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))]; | |
299 | ||
300 | if (!arq->on_hash) { | |
301 | WARN_ON(1); | |
302 | return; | |
303 | } | |
304 | ||
305 | if (arq->hash.prev != head) { | |
306 | list_del(&arq->hash); | |
307 | list_add(&arq->hash, head); | |
308 | } | |
309 | } | |
310 | ||
311 | static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset) | |
312 | { | |
313 | struct list_head *hash_list = &ad->hash[AS_HASH_FN(offset)]; | |
314 | struct list_head *entry, *next = hash_list->next; | |
315 | ||
316 | while ((entry = next) != hash_list) { | |
317 | struct as_rq *arq = list_entry_hash(entry); | |
318 | struct request *__rq = arq->request; | |
319 | ||
320 | next = entry->next; | |
321 | ||
322 | BUG_ON(!arq->on_hash); | |
323 | ||
324 | if (!rq_mergeable(__rq)) { | |
98b11471 | 325 | as_del_arq_hash(arq); |
1da177e4 LT |
326 | continue; |
327 | } | |
328 | ||
329 | if (rq_hash_key(__rq) == offset) | |
330 | return __rq; | |
331 | } | |
332 | ||
333 | return NULL; | |
334 | } | |
335 | ||
336 | /* | |
337 | * rb tree support functions | |
338 | */ | |
339 | #define RB_NONE (2) | |
340 | #define RB_EMPTY(root) ((root)->rb_node == NULL) | |
341 | #define ON_RB(node) ((node)->rb_color != RB_NONE) | |
342 | #define RB_CLEAR(node) ((node)->rb_color = RB_NONE) | |
343 | #define rb_entry_arq(node) rb_entry((node), struct as_rq, rb_node) | |
344 | #define ARQ_RB_ROOT(ad, arq) (&(ad)->sort_list[(arq)->is_sync]) | |
345 | #define rq_rb_key(rq) (rq)->sector | |
346 | ||
347 | /* | |
348 | * as_find_first_arq finds the first (lowest sector numbered) request | |
349 | * for the specified data_dir. Used to sweep back to the start of the disk | |
350 | * (1-way elevator) after we process the last (highest sector) request. | |
351 | */ | |
352 | static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir) | |
353 | { | |
354 | struct rb_node *n = ad->sort_list[data_dir].rb_node; | |
355 | ||
356 | if (n == NULL) | |
357 | return NULL; | |
358 | ||
359 | for (;;) { | |
360 | if (n->rb_left == NULL) | |
361 | return rb_entry_arq(n); | |
362 | ||
363 | n = n->rb_left; | |
364 | } | |
365 | } | |
366 | ||
367 | /* | |
368 | * Add the request to the rb tree if it is unique. If there is an alias (an | |
369 | * existing request against the same sector), which can happen when using | |
370 | * direct IO, then return the alias. | |
371 | */ | |
372 | static struct as_rq *as_add_arq_rb(struct as_data *ad, struct as_rq *arq) | |
373 | { | |
374 | struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node; | |
375 | struct rb_node *parent = NULL; | |
376 | struct as_rq *__arq; | |
377 | struct request *rq = arq->request; | |
378 | ||
379 | arq->rb_key = rq_rb_key(rq); | |
380 | ||
381 | while (*p) { | |
382 | parent = *p; | |
383 | __arq = rb_entry_arq(parent); | |
384 | ||
385 | if (arq->rb_key < __arq->rb_key) | |
386 | p = &(*p)->rb_left; | |
387 | else if (arq->rb_key > __arq->rb_key) | |
388 | p = &(*p)->rb_right; | |
389 | else | |
390 | return __arq; | |
391 | } | |
392 | ||
393 | rb_link_node(&arq->rb_node, parent, p); | |
394 | rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); | |
395 | ||
396 | return NULL; | |
397 | } | |
398 | ||
399 | static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq) | |
400 | { | |
401 | if (!ON_RB(&arq->rb_node)) { | |
402 | WARN_ON(1); | |
403 | return; | |
404 | } | |
405 | ||
406 | rb_erase(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); | |
407 | RB_CLEAR(&arq->rb_node); | |
408 | } | |
409 | ||
410 | static struct request * | |
411 | as_find_arq_rb(struct as_data *ad, sector_t sector, int data_dir) | |
412 | { | |
413 | struct rb_node *n = ad->sort_list[data_dir].rb_node; | |
414 | struct as_rq *arq; | |
415 | ||
416 | while (n) { | |
417 | arq = rb_entry_arq(n); | |
418 | ||
419 | if (sector < arq->rb_key) | |
420 | n = n->rb_left; | |
421 | else if (sector > arq->rb_key) | |
422 | n = n->rb_right; | |
423 | else | |
424 | return arq->request; | |
425 | } | |
426 | ||
427 | return NULL; | |
428 | } | |
429 | ||
430 | /* | |
431 | * IO Scheduler proper | |
432 | */ | |
433 | ||
434 | #define MAXBACK (1024 * 1024) /* | |
435 | * Maximum distance the disk will go backward | |
436 | * for a request. | |
437 | */ | |
438 | ||
439 | #define BACK_PENALTY 2 | |
440 | ||
441 | /* | |
442 | * as_choose_req selects the preferred one of two requests of the same data_dir | |
443 | * ignoring time - eg. timeouts, which is the job of as_dispatch_request | |
444 | */ | |
445 | static struct as_rq * | |
446 | as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2) | |
447 | { | |
448 | int data_dir; | |
449 | sector_t last, s1, s2, d1, d2; | |
450 | int r1_wrap=0, r2_wrap=0; /* requests are behind the disk head */ | |
451 | const sector_t maxback = MAXBACK; | |
452 | ||
453 | if (arq1 == NULL || arq1 == arq2) | |
454 | return arq2; | |
455 | if (arq2 == NULL) | |
456 | return arq1; | |
457 | ||
458 | data_dir = arq1->is_sync; | |
459 | ||
460 | last = ad->last_sector[data_dir]; | |
461 | s1 = arq1->request->sector; | |
462 | s2 = arq2->request->sector; | |
463 | ||
464 | BUG_ON(data_dir != arq2->is_sync); | |
465 | ||
466 | /* | |
467 | * Strict one way elevator _except_ in the case where we allow | |
468 | * short backward seeks which are biased as twice the cost of a | |
469 | * similar forward seek. | |
470 | */ | |
471 | if (s1 >= last) | |
472 | d1 = s1 - last; | |
473 | else if (s1+maxback >= last) | |
474 | d1 = (last - s1)*BACK_PENALTY; | |
475 | else { | |
476 | r1_wrap = 1; | |
477 | d1 = 0; /* shut up, gcc */ | |
478 | } | |
479 | ||
480 | if (s2 >= last) | |
481 | d2 = s2 - last; | |
482 | else if (s2+maxback >= last) | |
483 | d2 = (last - s2)*BACK_PENALTY; | |
484 | else { | |
485 | r2_wrap = 1; | |
486 | d2 = 0; | |
487 | } | |
488 | ||
489 | /* Found required data */ | |
490 | if (!r1_wrap && r2_wrap) | |
491 | return arq1; | |
492 | else if (!r2_wrap && r1_wrap) | |
493 | return arq2; | |
494 | else if (r1_wrap && r2_wrap) { | |
495 | /* both behind the head */ | |
496 | if (s1 <= s2) | |
497 | return arq1; | |
498 | else | |
499 | return arq2; | |
500 | } | |
501 | ||
502 | /* Both requests in front of the head */ | |
503 | if (d1 < d2) | |
504 | return arq1; | |
505 | else if (d2 < d1) | |
506 | return arq2; | |
507 | else { | |
508 | if (s1 >= s2) | |
509 | return arq1; | |
510 | else | |
511 | return arq2; | |
512 | } | |
513 | } | |
514 | ||
515 | /* | |
516 | * as_find_next_arq finds the next request after @prev in elevator order. | |
517 | * this with as_choose_req form the basis for how the scheduler chooses | |
518 | * what request to process next. Anticipation works on top of this. | |
519 | */ | |
520 | static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *last) | |
521 | { | |
522 | const int data_dir = last->is_sync; | |
523 | struct as_rq *ret; | |
524 | struct rb_node *rbnext = rb_next(&last->rb_node); | |
525 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
526 | struct as_rq *arq_next, *arq_prev; | |
527 | ||
528 | BUG_ON(!ON_RB(&last->rb_node)); | |
529 | ||
530 | if (rbprev) | |
531 | arq_prev = rb_entry_arq(rbprev); | |
532 | else | |
533 | arq_prev = NULL; | |
534 | ||
535 | if (rbnext) | |
536 | arq_next = rb_entry_arq(rbnext); | |
537 | else { | |
538 | arq_next = as_find_first_arq(ad, data_dir); | |
539 | if (arq_next == last) | |
540 | arq_next = NULL; | |
541 | } | |
542 | ||
543 | ret = as_choose_req(ad, arq_next, arq_prev); | |
544 | ||
545 | return ret; | |
546 | } | |
547 | ||
548 | /* | |
549 | * anticipatory scheduling functions follow | |
550 | */ | |
551 | ||
552 | /* | |
553 | * as_antic_expired tells us when we have anticipated too long. | |
554 | * The funny "absolute difference" math on the elapsed time is to handle | |
555 | * jiffy wraps, and disks which have been idle for 0x80000000 jiffies. | |
556 | */ | |
557 | static int as_antic_expired(struct as_data *ad) | |
558 | { | |
559 | long delta_jif; | |
560 | ||
561 | delta_jif = jiffies - ad->antic_start; | |
562 | if (unlikely(delta_jif < 0)) | |
563 | delta_jif = -delta_jif; | |
564 | if (delta_jif < ad->antic_expire) | |
565 | return 0; | |
566 | ||
567 | return 1; | |
568 | } | |
569 | ||
570 | /* | |
571 | * as_antic_waitnext starts anticipating that a nice request will soon be | |
572 | * submitted. See also as_antic_waitreq | |
573 | */ | |
574 | static void as_antic_waitnext(struct as_data *ad) | |
575 | { | |
576 | unsigned long timeout; | |
577 | ||
578 | BUG_ON(ad->antic_status != ANTIC_OFF | |
579 | && ad->antic_status != ANTIC_WAIT_REQ); | |
580 | ||
581 | timeout = ad->antic_start + ad->antic_expire; | |
582 | ||
583 | mod_timer(&ad->antic_timer, timeout); | |
584 | ||
585 | ad->antic_status = ANTIC_WAIT_NEXT; | |
586 | } | |
587 | ||
588 | /* | |
589 | * as_antic_waitreq starts anticipating. We don't start timing the anticipation | |
590 | * until the request that we're anticipating on has finished. This means we | |
591 | * are timing from when the candidate process wakes up hopefully. | |
592 | */ | |
593 | static void as_antic_waitreq(struct as_data *ad) | |
594 | { | |
595 | BUG_ON(ad->antic_status == ANTIC_FINISHED); | |
596 | if (ad->antic_status == ANTIC_OFF) { | |
597 | if (!ad->io_context || ad->ioc_finished) | |
598 | as_antic_waitnext(ad); | |
599 | else | |
600 | ad->antic_status = ANTIC_WAIT_REQ; | |
601 | } | |
602 | } | |
603 | ||
604 | /* | |
605 | * This is called directly by the functions in this file to stop anticipation. | |
606 | * We kill the timer and schedule a call to the request_fn asap. | |
607 | */ | |
608 | static void as_antic_stop(struct as_data *ad) | |
609 | { | |
610 | int status = ad->antic_status; | |
611 | ||
612 | if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) { | |
613 | if (status == ANTIC_WAIT_NEXT) | |
614 | del_timer(&ad->antic_timer); | |
615 | ad->antic_status = ANTIC_FINISHED; | |
616 | /* see as_work_handler */ | |
617 | kblockd_schedule_work(&ad->antic_work); | |
618 | } | |
619 | } | |
620 | ||
621 | /* | |
622 | * as_antic_timeout is the timer function set by as_antic_waitnext. | |
623 | */ | |
624 | static void as_antic_timeout(unsigned long data) | |
625 | { | |
626 | struct request_queue *q = (struct request_queue *)data; | |
627 | struct as_data *ad = q->elevator->elevator_data; | |
628 | unsigned long flags; | |
629 | ||
630 | spin_lock_irqsave(q->queue_lock, flags); | |
631 | if (ad->antic_status == ANTIC_WAIT_REQ | |
632 | || ad->antic_status == ANTIC_WAIT_NEXT) { | |
633 | struct as_io_context *aic = ad->io_context->aic; | |
634 | ||
635 | ad->antic_status = ANTIC_FINISHED; | |
636 | kblockd_schedule_work(&ad->antic_work); | |
637 | ||
638 | if (aic->ttime_samples == 0) { | |
639 | /* process anticipated on has exitted or timed out*/ | |
640 | ad->exit_prob = (7*ad->exit_prob + 256)/8; | |
641 | } | |
642 | } | |
643 | spin_unlock_irqrestore(q->queue_lock, flags); | |
644 | } | |
645 | ||
646 | /* | |
647 | * as_close_req decides if one request is considered "close" to the | |
648 | * previous one issued. | |
649 | */ | |
650 | static int as_close_req(struct as_data *ad, struct as_rq *arq) | |
651 | { | |
652 | unsigned long delay; /* milliseconds */ | |
653 | sector_t last = ad->last_sector[ad->batch_data_dir]; | |
654 | sector_t next = arq->request->sector; | |
655 | sector_t delta; /* acceptable close offset (in sectors) */ | |
656 | ||
657 | if (ad->antic_status == ANTIC_OFF || !ad->ioc_finished) | |
658 | delay = 0; | |
659 | else | |
660 | delay = ((jiffies - ad->antic_start) * 1000) / HZ; | |
661 | ||
662 | if (delay <= 1) | |
663 | delta = 64; | |
664 | else if (delay <= 20 && delay <= ad->antic_expire) | |
665 | delta = 64 << (delay-1); | |
666 | else | |
667 | return 1; | |
668 | ||
669 | return (last - (delta>>1) <= next) && (next <= last + delta); | |
670 | } | |
671 | ||
672 | /* | |
673 | * as_can_break_anticipation returns true if we have been anticipating this | |
674 | * request. | |
675 | * | |
676 | * It also returns true if the process against which we are anticipating | |
677 | * submits a write - that's presumably an fsync, O_SYNC write, etc. We want to | |
678 | * dispatch it ASAP, because we know that application will not be submitting | |
679 | * any new reads. | |
680 | * | |
681 | * If the task which has submitted the request has exitted, break anticipation. | |
682 | * | |
683 | * If this task has queued some other IO, do not enter enticipation. | |
684 | */ | |
685 | static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq) | |
686 | { | |
687 | struct io_context *ioc; | |
688 | struct as_io_context *aic; | |
689 | sector_t s; | |
690 | ||
691 | ioc = ad->io_context; | |
692 | BUG_ON(!ioc); | |
693 | ||
694 | if (arq && ioc == arq->io_context) { | |
695 | /* request from same process */ | |
696 | return 1; | |
697 | } | |
698 | ||
699 | if (ad->ioc_finished && as_antic_expired(ad)) { | |
700 | /* | |
701 | * In this situation status should really be FINISHED, | |
702 | * however the timer hasn't had the chance to run yet. | |
703 | */ | |
704 | return 1; | |
705 | } | |
706 | ||
707 | aic = ioc->aic; | |
708 | if (!aic) | |
709 | return 0; | |
710 | ||
711 | if (!test_bit(AS_TASK_RUNNING, &aic->state)) { | |
712 | /* process anticipated on has exitted */ | |
713 | if (aic->ttime_samples == 0) | |
714 | ad->exit_prob = (7*ad->exit_prob + 256)/8; | |
715 | return 1; | |
716 | } | |
717 | ||
718 | if (atomic_read(&aic->nr_queued) > 0) { | |
719 | /* process has more requests queued */ | |
720 | return 1; | |
721 | } | |
722 | ||
723 | if (atomic_read(&aic->nr_dispatched) > 0) { | |
724 | /* process has more requests dispatched */ | |
725 | return 1; | |
726 | } | |
727 | ||
728 | if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, arq)) { | |
729 | /* | |
730 | * Found a close request that is not one of ours. | |
731 | * | |
732 | * This makes close requests from another process reset | |
733 | * our thinktime delay. Is generally useful when there are | |
734 | * two or more cooperating processes working in the same | |
735 | * area. | |
736 | */ | |
737 | spin_lock(&aic->lock); | |
738 | aic->last_end_request = jiffies; | |
739 | spin_unlock(&aic->lock); | |
740 | return 1; | |
741 | } | |
742 | ||
743 | ||
744 | if (aic->ttime_samples == 0) { | |
745 | if (ad->new_ttime_mean > ad->antic_expire) | |
746 | return 1; | |
747 | if (ad->exit_prob > 128) | |
748 | return 1; | |
749 | } else if (aic->ttime_mean > ad->antic_expire) { | |
750 | /* the process thinks too much between requests */ | |
751 | return 1; | |
752 | } | |
753 | ||
754 | if (!arq) | |
755 | return 0; | |
756 | ||
757 | if (ad->last_sector[REQ_SYNC] < arq->request->sector) | |
758 | s = arq->request->sector - ad->last_sector[REQ_SYNC]; | |
759 | else | |
760 | s = ad->last_sector[REQ_SYNC] - arq->request->sector; | |
761 | ||
762 | if (aic->seek_samples == 0) { | |
763 | /* | |
764 | * Process has just started IO. Use past statistics to | |
765 | * guage success possibility | |
766 | */ | |
767 | if (ad->new_seek_mean > s) { | |
768 | /* this request is better than what we're expecting */ | |
769 | return 1; | |
770 | } | |
771 | ||
772 | } else { | |
773 | if (aic->seek_mean > s) { | |
774 | /* this request is better than what we're expecting */ | |
775 | return 1; | |
776 | } | |
777 | } | |
778 | ||
779 | return 0; | |
780 | } | |
781 | ||
782 | /* | |
783 | * as_can_anticipate indicates weather we should either run arq | |
784 | * or keep anticipating a better request. | |
785 | */ | |
786 | static int as_can_anticipate(struct as_data *ad, struct as_rq *arq) | |
787 | { | |
788 | if (!ad->io_context) | |
789 | /* | |
790 | * Last request submitted was a write | |
791 | */ | |
792 | return 0; | |
793 | ||
794 | if (ad->antic_status == ANTIC_FINISHED) | |
795 | /* | |
796 | * Don't restart if we have just finished. Run the next request | |
797 | */ | |
798 | return 0; | |
799 | ||
800 | if (as_can_break_anticipation(ad, arq)) | |
801 | /* | |
802 | * This request is a good candidate. Don't keep anticipating, | |
803 | * run it. | |
804 | */ | |
805 | return 0; | |
806 | ||
807 | /* | |
808 | * OK from here, we haven't finished, and don't have a decent request! | |
809 | * Status is either ANTIC_OFF so start waiting, | |
810 | * ANTIC_WAIT_REQ so continue waiting for request to finish | |
811 | * or ANTIC_WAIT_NEXT so continue waiting for an acceptable request. | |
812 | * | |
813 | */ | |
814 | ||
815 | return 1; | |
816 | } | |
817 | ||
818 | static void as_update_thinktime(struct as_data *ad, struct as_io_context *aic, unsigned long ttime) | |
819 | { | |
820 | /* fixed point: 1.0 == 1<<8 */ | |
821 | if (aic->ttime_samples == 0) { | |
822 | ad->new_ttime_total = (7*ad->new_ttime_total + 256*ttime) / 8; | |
823 | ad->new_ttime_mean = ad->new_ttime_total / 256; | |
824 | ||
825 | ad->exit_prob = (7*ad->exit_prob)/8; | |
826 | } | |
827 | aic->ttime_samples = (7*aic->ttime_samples + 256) / 8; | |
828 | aic->ttime_total = (7*aic->ttime_total + 256*ttime) / 8; | |
829 | aic->ttime_mean = (aic->ttime_total + 128) / aic->ttime_samples; | |
830 | } | |
831 | ||
832 | static void as_update_seekdist(struct as_data *ad, struct as_io_context *aic, sector_t sdist) | |
833 | { | |
834 | u64 total; | |
835 | ||
836 | if (aic->seek_samples == 0) { | |
837 | ad->new_seek_total = (7*ad->new_seek_total + 256*(u64)sdist)/8; | |
838 | ad->new_seek_mean = ad->new_seek_total / 256; | |
839 | } | |
840 | ||
841 | /* | |
842 | * Don't allow the seek distance to get too large from the | |
843 | * odd fragment, pagein, etc | |
844 | */ | |
845 | if (aic->seek_samples <= 60) /* second&third seek */ | |
846 | sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*1024); | |
847 | else | |
848 | sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*64); | |
849 | ||
850 | aic->seek_samples = (7*aic->seek_samples + 256) / 8; | |
851 | aic->seek_total = (7*aic->seek_total + (u64)256*sdist) / 8; | |
852 | total = aic->seek_total + (aic->seek_samples/2); | |
853 | do_div(total, aic->seek_samples); | |
854 | aic->seek_mean = (sector_t)total; | |
855 | } | |
856 | ||
857 | /* | |
858 | * as_update_iohist keeps a decaying histogram of IO thinktimes, and | |
859 | * updates @aic->ttime_mean based on that. It is called when a new | |
860 | * request is queued. | |
861 | */ | |
862 | static void as_update_iohist(struct as_data *ad, struct as_io_context *aic, struct request *rq) | |
863 | { | |
864 | struct as_rq *arq = RQ_DATA(rq); | |
865 | int data_dir = arq->is_sync; | |
866 | unsigned long thinktime; | |
867 | sector_t seek_dist; | |
868 | ||
869 | if (aic == NULL) | |
870 | return; | |
871 | ||
872 | if (data_dir == REQ_SYNC) { | |
873 | unsigned long in_flight = atomic_read(&aic->nr_queued) | |
874 | + atomic_read(&aic->nr_dispatched); | |
875 | spin_lock(&aic->lock); | |
876 | if (test_bit(AS_TASK_IORUNNING, &aic->state) || | |
877 | test_bit(AS_TASK_IOSTARTED, &aic->state)) { | |
878 | /* Calculate read -> read thinktime */ | |
879 | if (test_bit(AS_TASK_IORUNNING, &aic->state) | |
880 | && in_flight == 0) { | |
881 | thinktime = jiffies - aic->last_end_request; | |
882 | thinktime = min(thinktime, MAX_THINKTIME-1); | |
883 | } else | |
884 | thinktime = 0; | |
885 | as_update_thinktime(ad, aic, thinktime); | |
886 | ||
887 | /* Calculate read -> read seek distance */ | |
888 | if (aic->last_request_pos < rq->sector) | |
889 | seek_dist = rq->sector - aic->last_request_pos; | |
890 | else | |
891 | seek_dist = aic->last_request_pos - rq->sector; | |
892 | as_update_seekdist(ad, aic, seek_dist); | |
893 | } | |
894 | aic->last_request_pos = rq->sector + rq->nr_sectors; | |
895 | set_bit(AS_TASK_IOSTARTED, &aic->state); | |
896 | spin_unlock(&aic->lock); | |
897 | } | |
898 | } | |
899 | ||
900 | /* | |
901 | * as_update_arq must be called whenever a request (arq) is added to | |
902 | * the sort_list. This function keeps caches up to date, and checks if the | |
903 | * request might be one we are "anticipating" | |
904 | */ | |
905 | static void as_update_arq(struct as_data *ad, struct as_rq *arq) | |
906 | { | |
907 | const int data_dir = arq->is_sync; | |
908 | ||
909 | /* keep the next_arq cache up to date */ | |
910 | ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]); | |
911 | ||
912 | /* | |
913 | * have we been anticipating this request? | |
914 | * or does it come from the same process as the one we are anticipating | |
915 | * for? | |
916 | */ | |
917 | if (ad->antic_status == ANTIC_WAIT_REQ | |
918 | || ad->antic_status == ANTIC_WAIT_NEXT) { | |
919 | if (as_can_break_anticipation(ad, arq)) | |
920 | as_antic_stop(ad); | |
921 | } | |
922 | } | |
923 | ||
924 | /* | |
925 | * Gathers timings and resizes the write batch automatically | |
926 | */ | |
927 | static void update_write_batch(struct as_data *ad) | |
928 | { | |
929 | unsigned long batch = ad->batch_expire[REQ_ASYNC]; | |
930 | long write_time; | |
931 | ||
932 | write_time = (jiffies - ad->current_batch_expires) + batch; | |
933 | if (write_time < 0) | |
934 | write_time = 0; | |
935 | ||
936 | if (write_time > batch && !ad->write_batch_idled) { | |
937 | if (write_time > batch * 3) | |
938 | ad->write_batch_count /= 2; | |
939 | else | |
940 | ad->write_batch_count--; | |
941 | } else if (write_time < batch && ad->current_write_count == 0) { | |
942 | if (batch > write_time * 3) | |
943 | ad->write_batch_count *= 2; | |
944 | else | |
945 | ad->write_batch_count++; | |
946 | } | |
947 | ||
948 | if (ad->write_batch_count < 1) | |
949 | ad->write_batch_count = 1; | |
950 | } | |
951 | ||
952 | /* | |
953 | * as_completed_request is to be called when a request has completed and | |
954 | * returned something to the requesting process, be it an error or data. | |
955 | */ | |
956 | static void as_completed_request(request_queue_t *q, struct request *rq) | |
957 | { | |
958 | struct as_data *ad = q->elevator->elevator_data; | |
959 | struct as_rq *arq = RQ_DATA(rq); | |
960 | ||
961 | WARN_ON(!list_empty(&rq->queuelist)); | |
962 | ||
1da177e4 LT |
963 | if (arq->state != AS_RQ_REMOVED) { |
964 | printk("arq->state %d\n", arq->state); | |
965 | WARN_ON(1); | |
966 | goto out; | |
967 | } | |
968 | ||
1da177e4 LT |
969 | if (ad->changed_batch && ad->nr_dispatched == 1) { |
970 | kblockd_schedule_work(&ad->antic_work); | |
971 | ad->changed_batch = 0; | |
972 | ||
973 | if (ad->batch_data_dir == REQ_SYNC) | |
974 | ad->new_batch = 1; | |
975 | } | |
976 | WARN_ON(ad->nr_dispatched == 0); | |
977 | ad->nr_dispatched--; | |
978 | ||
979 | /* | |
980 | * Start counting the batch from when a request of that direction is | |
981 | * actually serviced. This should help devices with big TCQ windows | |
982 | * and writeback caches | |
983 | */ | |
984 | if (ad->new_batch && ad->batch_data_dir == arq->is_sync) { | |
985 | update_write_batch(ad); | |
986 | ad->current_batch_expires = jiffies + | |
987 | ad->batch_expire[REQ_SYNC]; | |
988 | ad->new_batch = 0; | |
989 | } | |
990 | ||
991 | if (ad->io_context == arq->io_context && ad->io_context) { | |
992 | ad->antic_start = jiffies; | |
993 | ad->ioc_finished = 1; | |
994 | if (ad->antic_status == ANTIC_WAIT_REQ) { | |
995 | /* | |
996 | * We were waiting on this request, now anticipate | |
997 | * the next one | |
998 | */ | |
999 | as_antic_waitnext(ad); | |
1000 | } | |
1001 | } | |
1002 | ||
b4878f24 | 1003 | as_put_io_context(arq); |
1da177e4 LT |
1004 | out: |
1005 | arq->state = AS_RQ_POSTSCHED; | |
1006 | } | |
1007 | ||
1008 | /* | |
1009 | * as_remove_queued_request removes a request from the pre dispatch queue | |
1010 | * without updating refcounts. It is expected the caller will drop the | |
1011 | * reference unless it replaces the request at somepart of the elevator | |
1012 | * (ie. the dispatch queue) | |
1013 | */ | |
1014 | static void as_remove_queued_request(request_queue_t *q, struct request *rq) | |
1015 | { | |
1016 | struct as_rq *arq = RQ_DATA(rq); | |
1017 | const int data_dir = arq->is_sync; | |
1018 | struct as_data *ad = q->elevator->elevator_data; | |
1019 | ||
1020 | WARN_ON(arq->state != AS_RQ_QUEUED); | |
1021 | ||
1022 | if (arq->io_context && arq->io_context->aic) { | |
1023 | BUG_ON(!atomic_read(&arq->io_context->aic->nr_queued)); | |
1024 | atomic_dec(&arq->io_context->aic->nr_queued); | |
1025 | } | |
1026 | ||
1027 | /* | |
1028 | * Update the "next_arq" cache if we are about to remove its | |
1029 | * entry | |
1030 | */ | |
1031 | if (ad->next_arq[data_dir] == arq) | |
1032 | ad->next_arq[data_dir] = as_find_next_arq(ad, arq); | |
1033 | ||
1034 | list_del_init(&arq->fifo); | |
98b11471 | 1035 | as_del_arq_hash(arq); |
1da177e4 LT |
1036 | as_del_arq_rb(ad, arq); |
1037 | } | |
1038 | ||
1da177e4 LT |
1039 | /* |
1040 | * as_fifo_expired returns 0 if there are no expired reads on the fifo, | |
1041 | * 1 otherwise. It is ratelimited so that we only perform the check once per | |
1042 | * `fifo_expire' interval. Otherwise a large number of expired requests | |
1043 | * would create a hopeless seekstorm. | |
1044 | * | |
1045 | * See as_antic_expired comment. | |
1046 | */ | |
1047 | static int as_fifo_expired(struct as_data *ad, int adir) | |
1048 | { | |
1049 | struct as_rq *arq; | |
1050 | long delta_jif; | |
1051 | ||
1052 | delta_jif = jiffies - ad->last_check_fifo[adir]; | |
1053 | if (unlikely(delta_jif < 0)) | |
1054 | delta_jif = -delta_jif; | |
1055 | if (delta_jif < ad->fifo_expire[adir]) | |
1056 | return 0; | |
1057 | ||
1058 | ad->last_check_fifo[adir] = jiffies; | |
1059 | ||
1060 | if (list_empty(&ad->fifo_list[adir])) | |
1061 | return 0; | |
1062 | ||
1063 | arq = list_entry_fifo(ad->fifo_list[adir].next); | |
1064 | ||
1065 | return time_after(jiffies, arq->expires); | |
1066 | } | |
1067 | ||
1068 | /* | |
1069 | * as_batch_expired returns true if the current batch has expired. A batch | |
1070 | * is a set of reads or a set of writes. | |
1071 | */ | |
1072 | static inline int as_batch_expired(struct as_data *ad) | |
1073 | { | |
1074 | if (ad->changed_batch || ad->new_batch) | |
1075 | return 0; | |
1076 | ||
1077 | if (ad->batch_data_dir == REQ_SYNC) | |
1078 | /* TODO! add a check so a complete fifo gets written? */ | |
1079 | return time_after(jiffies, ad->current_batch_expires); | |
1080 | ||
1081 | return time_after(jiffies, ad->current_batch_expires) | |
1082 | || ad->current_write_count == 0; | |
1083 | } | |
1084 | ||
1085 | /* | |
1086 | * move an entry to dispatch queue | |
1087 | */ | |
1088 | static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq) | |
1089 | { | |
1090 | struct request *rq = arq->request; | |
1da177e4 LT |
1091 | const int data_dir = arq->is_sync; |
1092 | ||
1093 | BUG_ON(!ON_RB(&arq->rb_node)); | |
1094 | ||
1095 | as_antic_stop(ad); | |
1096 | ad->antic_status = ANTIC_OFF; | |
1097 | ||
1098 | /* | |
1099 | * This has to be set in order to be correctly updated by | |
1100 | * as_find_next_arq | |
1101 | */ | |
1102 | ad->last_sector[data_dir] = rq->sector + rq->nr_sectors; | |
1103 | ||
1104 | if (data_dir == REQ_SYNC) { | |
1105 | /* In case we have to anticipate after this */ | |
1106 | copy_io_context(&ad->io_context, &arq->io_context); | |
1107 | } else { | |
1108 | if (ad->io_context) { | |
1109 | put_io_context(ad->io_context); | |
1110 | ad->io_context = NULL; | |
1111 | } | |
1112 | ||
1113 | if (ad->current_write_count != 0) | |
1114 | ad->current_write_count--; | |
1115 | } | |
1116 | ad->ioc_finished = 0; | |
1117 | ||
1118 | ad->next_arq[data_dir] = as_find_next_arq(ad, arq); | |
1119 | ||
1120 | /* | |
1121 | * take it off the sort and fifo list, add to dispatch queue | |
1122 | */ | |
1da177e4 LT |
1123 | while (!list_empty(&rq->queuelist)) { |
1124 | struct request *__rq = list_entry_rq(rq->queuelist.next); | |
1125 | struct as_rq *__arq = RQ_DATA(__rq); | |
1126 | ||
b4878f24 JA |
1127 | list_del(&__rq->queuelist); |
1128 | ||
1129 | elv_dispatch_add_tail(ad->q, __rq); | |
1da177e4 LT |
1130 | |
1131 | if (__arq->io_context && __arq->io_context->aic) | |
1132 | atomic_inc(&__arq->io_context->aic->nr_dispatched); | |
1133 | ||
1134 | WARN_ON(__arq->state != AS_RQ_QUEUED); | |
1135 | __arq->state = AS_RQ_DISPATCHED; | |
1136 | ||
1137 | ad->nr_dispatched++; | |
1138 | } | |
1139 | ||
1140 | as_remove_queued_request(ad->q, rq); | |
1141 | WARN_ON(arq->state != AS_RQ_QUEUED); | |
1142 | ||
b4878f24 JA |
1143 | elv_dispatch_sort(ad->q, rq); |
1144 | ||
1da177e4 LT |
1145 | arq->state = AS_RQ_DISPATCHED; |
1146 | if (arq->io_context && arq->io_context->aic) | |
1147 | atomic_inc(&arq->io_context->aic->nr_dispatched); | |
1148 | ad->nr_dispatched++; | |
1149 | } | |
1150 | ||
1151 | /* | |
1152 | * as_dispatch_request selects the best request according to | |
1153 | * read/write expire, batch expire, etc, and moves it to the dispatch | |
1154 | * queue. Returns 1 if a request was found, 0 otherwise. | |
1155 | */ | |
b4878f24 | 1156 | static int as_dispatch_request(request_queue_t *q, int force) |
1da177e4 | 1157 | { |
b4878f24 | 1158 | struct as_data *ad = q->elevator->elevator_data; |
1da177e4 LT |
1159 | struct as_rq *arq; |
1160 | const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]); | |
1161 | const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]); | |
1162 | ||
b4878f24 JA |
1163 | if (unlikely(force)) { |
1164 | /* | |
1165 | * Forced dispatch, accounting is useless. Reset | |
1166 | * accounting states and dump fifo_lists. Note that | |
1167 | * batch_data_dir is reset to REQ_SYNC to avoid | |
1168 | * screwing write batch accounting as write batch | |
1169 | * accounting occurs on W->R transition. | |
1170 | */ | |
1171 | int dispatched = 0; | |
1172 | ||
1173 | ad->batch_data_dir = REQ_SYNC; | |
1174 | ad->changed_batch = 0; | |
1175 | ad->new_batch = 0; | |
1176 | ||
1177 | while (ad->next_arq[REQ_SYNC]) { | |
1178 | as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]); | |
1179 | dispatched++; | |
1180 | } | |
1181 | ad->last_check_fifo[REQ_SYNC] = jiffies; | |
1182 | ||
1183 | while (ad->next_arq[REQ_ASYNC]) { | |
1184 | as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]); | |
1185 | dispatched++; | |
1186 | } | |
1187 | ad->last_check_fifo[REQ_ASYNC] = jiffies; | |
1188 | ||
1189 | return dispatched; | |
1190 | } | |
1191 | ||
1da177e4 LT |
1192 | /* Signal that the write batch was uncontended, so we can't time it */ |
1193 | if (ad->batch_data_dir == REQ_ASYNC && !reads) { | |
1194 | if (ad->current_write_count == 0 || !writes) | |
1195 | ad->write_batch_idled = 1; | |
1196 | } | |
1197 | ||
1198 | if (!(reads || writes) | |
1199 | || ad->antic_status == ANTIC_WAIT_REQ | |
1200 | || ad->antic_status == ANTIC_WAIT_NEXT | |
1201 | || ad->changed_batch) | |
1202 | return 0; | |
1203 | ||
1204 | if (!(reads && writes && as_batch_expired(ad)) ) { | |
1205 | /* | |
1206 | * batch is still running or no reads or no writes | |
1207 | */ | |
1208 | arq = ad->next_arq[ad->batch_data_dir]; | |
1209 | ||
1210 | if (ad->batch_data_dir == REQ_SYNC && ad->antic_expire) { | |
1211 | if (as_fifo_expired(ad, REQ_SYNC)) | |
1212 | goto fifo_expired; | |
1213 | ||
1214 | if (as_can_anticipate(ad, arq)) { | |
1215 | as_antic_waitreq(ad); | |
1216 | return 0; | |
1217 | } | |
1218 | } | |
1219 | ||
1220 | if (arq) { | |
1221 | /* we have a "next request" */ | |
1222 | if (reads && !writes) | |
1223 | ad->current_batch_expires = | |
1224 | jiffies + ad->batch_expire[REQ_SYNC]; | |
1225 | goto dispatch_request; | |
1226 | } | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * at this point we are not running a batch. select the appropriate | |
1231 | * data direction (read / write) | |
1232 | */ | |
1233 | ||
1234 | if (reads) { | |
1235 | BUG_ON(RB_EMPTY(&ad->sort_list[REQ_SYNC])); | |
1236 | ||
1237 | if (writes && ad->batch_data_dir == REQ_SYNC) | |
1238 | /* | |
1239 | * Last batch was a read, switch to writes | |
1240 | */ | |
1241 | goto dispatch_writes; | |
1242 | ||
1243 | if (ad->batch_data_dir == REQ_ASYNC) { | |
1244 | WARN_ON(ad->new_batch); | |
1245 | ad->changed_batch = 1; | |
1246 | } | |
1247 | ad->batch_data_dir = REQ_SYNC; | |
1248 | arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); | |
1249 | ad->last_check_fifo[ad->batch_data_dir] = jiffies; | |
1250 | goto dispatch_request; | |
1251 | } | |
1252 | ||
1253 | /* | |
1254 | * the last batch was a read | |
1255 | */ | |
1256 | ||
1257 | if (writes) { | |
1258 | dispatch_writes: | |
1259 | BUG_ON(RB_EMPTY(&ad->sort_list[REQ_ASYNC])); | |
1260 | ||
1261 | if (ad->batch_data_dir == REQ_SYNC) { | |
1262 | ad->changed_batch = 1; | |
1263 | ||
1264 | /* | |
1265 | * new_batch might be 1 when the queue runs out of | |
1266 | * reads. A subsequent submission of a write might | |
1267 | * cause a change of batch before the read is finished. | |
1268 | */ | |
1269 | ad->new_batch = 0; | |
1270 | } | |
1271 | ad->batch_data_dir = REQ_ASYNC; | |
1272 | ad->current_write_count = ad->write_batch_count; | |
1273 | ad->write_batch_idled = 0; | |
1274 | arq = ad->next_arq[ad->batch_data_dir]; | |
1275 | goto dispatch_request; | |
1276 | } | |
1277 | ||
1278 | BUG(); | |
1279 | return 0; | |
1280 | ||
1281 | dispatch_request: | |
1282 | /* | |
1283 | * If a request has expired, service it. | |
1284 | */ | |
1285 | ||
1286 | if (as_fifo_expired(ad, ad->batch_data_dir)) { | |
1287 | fifo_expired: | |
1288 | arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); | |
1289 | BUG_ON(arq == NULL); | |
1290 | } | |
1291 | ||
1292 | if (ad->changed_batch) { | |
1293 | WARN_ON(ad->new_batch); | |
1294 | ||
1295 | if (ad->nr_dispatched) | |
1296 | return 0; | |
1297 | ||
1298 | if (ad->batch_data_dir == REQ_ASYNC) | |
1299 | ad->current_batch_expires = jiffies + | |
1300 | ad->batch_expire[REQ_ASYNC]; | |
1301 | else | |
1302 | ad->new_batch = 1; | |
1303 | ||
1304 | ad->changed_batch = 0; | |
1305 | } | |
1306 | ||
1307 | /* | |
1308 | * arq is the selected appropriate request. | |
1309 | */ | |
1310 | as_move_to_dispatch(ad, arq); | |
1311 | ||
1312 | return 1; | |
1313 | } | |
1314 | ||
1da177e4 LT |
1315 | /* |
1316 | * Add arq to a list behind alias | |
1317 | */ | |
1318 | static inline void | |
1319 | as_add_aliased_request(struct as_data *ad, struct as_rq *arq, struct as_rq *alias) | |
1320 | { | |
1321 | struct request *req = arq->request; | |
1322 | struct list_head *insert = alias->request->queuelist.prev; | |
1323 | ||
1324 | /* | |
1325 | * Transfer list of aliases | |
1326 | */ | |
1327 | while (!list_empty(&req->queuelist)) { | |
1328 | struct request *__rq = list_entry_rq(req->queuelist.next); | |
1329 | struct as_rq *__arq = RQ_DATA(__rq); | |
1330 | ||
1331 | list_move_tail(&__rq->queuelist, &alias->request->queuelist); | |
1332 | ||
1333 | WARN_ON(__arq->state != AS_RQ_QUEUED); | |
1334 | } | |
1335 | ||
1336 | /* | |
1337 | * Another request with the same start sector on the rbtree. | |
1338 | * Link this request to that sector. They are untangled in | |
1339 | * as_move_to_dispatch | |
1340 | */ | |
1341 | list_add(&arq->request->queuelist, insert); | |
1342 | ||
1343 | /* | |
1344 | * Don't want to have to handle merges. | |
1345 | */ | |
98b11471 | 1346 | as_del_arq_hash(arq); |
47e627ce | 1347 | arq->request->flags |= REQ_NOMERGE; |
1da177e4 LT |
1348 | } |
1349 | ||
1350 | /* | |
1351 | * add arq to rbtree and fifo | |
1352 | */ | |
b4878f24 | 1353 | static void as_add_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1354 | { |
b4878f24 JA |
1355 | struct as_data *ad = q->elevator->elevator_data; |
1356 | struct as_rq *arq = RQ_DATA(rq); | |
1da177e4 LT |
1357 | struct as_rq *alias; |
1358 | int data_dir; | |
1359 | ||
b4878f24 JA |
1360 | if (arq->state != AS_RQ_PRESCHED) { |
1361 | printk("arq->state: %d\n", arq->state); | |
1362 | WARN_ON(1); | |
1363 | } | |
1364 | arq->state = AS_RQ_NEW; | |
1365 | ||
1da177e4 LT |
1366 | if (rq_data_dir(arq->request) == READ |
1367 | || current->flags&PF_SYNCWRITE) | |
1368 | arq->is_sync = 1; | |
1369 | else | |
1370 | arq->is_sync = 0; | |
1371 | data_dir = arq->is_sync; | |
1372 | ||
1373 | arq->io_context = as_get_io_context(); | |
1374 | ||
1375 | if (arq->io_context) { | |
1376 | as_update_iohist(ad, arq->io_context->aic, arq->request); | |
1377 | atomic_inc(&arq->io_context->aic->nr_queued); | |
1378 | } | |
1379 | ||
1380 | alias = as_add_arq_rb(ad, arq); | |
1381 | if (!alias) { | |
1382 | /* | |
1383 | * set expire time (only used for reads) and add to fifo list | |
1384 | */ | |
1385 | arq->expires = jiffies + ad->fifo_expire[data_dir]; | |
1386 | list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]); | |
1387 | ||
98b11471 | 1388 | if (rq_mergeable(arq->request)) |
1da177e4 | 1389 | as_add_arq_hash(ad, arq); |
1da177e4 LT |
1390 | as_update_arq(ad, arq); /* keep state machine up to date */ |
1391 | ||
1392 | } else { | |
1393 | as_add_aliased_request(ad, arq, alias); | |
1394 | ||
1395 | /* | |
1396 | * have we been anticipating this request? | |
1397 | * or does it come from the same process as the one we are | |
1398 | * anticipating for? | |
1399 | */ | |
1400 | if (ad->antic_status == ANTIC_WAIT_REQ | |
1401 | || ad->antic_status == ANTIC_WAIT_NEXT) { | |
1402 | if (as_can_break_anticipation(ad, arq)) | |
1403 | as_antic_stop(ad); | |
1404 | } | |
1405 | } | |
1406 | ||
1407 | arq->state = AS_RQ_QUEUED; | |
1408 | } | |
1409 | ||
b4878f24 | 1410 | static void as_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1411 | { |
1da177e4 LT |
1412 | struct as_rq *arq = RQ_DATA(rq); |
1413 | ||
b4878f24 JA |
1414 | WARN_ON(arq->state != AS_RQ_DISPATCHED); |
1415 | arq->state = AS_RQ_REMOVED; | |
1416 | if (arq->io_context && arq->io_context->aic) | |
1417 | atomic_dec(&arq->io_context->aic->nr_dispatched); | |
1da177e4 LT |
1418 | } |
1419 | ||
b4878f24 | 1420 | static void as_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1421 | { |
1da177e4 LT |
1422 | struct as_rq *arq = RQ_DATA(rq); |
1423 | ||
b4878f24 JA |
1424 | WARN_ON(arq->state != AS_RQ_REMOVED); |
1425 | arq->state = AS_RQ_DISPATCHED; | |
1426 | if (arq->io_context && arq->io_context->aic) | |
1427 | atomic_inc(&arq->io_context->aic->nr_dispatched); | |
1da177e4 LT |
1428 | } |
1429 | ||
1430 | /* | |
1431 | * as_queue_empty tells us if there are requests left in the device. It may | |
1432 | * not be the case that a driver can get the next request even if the queue | |
1433 | * is not empty - it is used in the block layer to check for plugging and | |
1434 | * merging opportunities | |
1435 | */ | |
1436 | static int as_queue_empty(request_queue_t *q) | |
1437 | { | |
1438 | struct as_data *ad = q->elevator->elevator_data; | |
1439 | ||
b4878f24 JA |
1440 | return list_empty(&ad->fifo_list[REQ_ASYNC]) |
1441 | && list_empty(&ad->fifo_list[REQ_SYNC]); | |
1da177e4 LT |
1442 | } |
1443 | ||
1444 | static struct request * | |
1445 | as_former_request(request_queue_t *q, struct request *rq) | |
1446 | { | |
1447 | struct as_rq *arq = RQ_DATA(rq); | |
1448 | struct rb_node *rbprev = rb_prev(&arq->rb_node); | |
1449 | struct request *ret = NULL; | |
1450 | ||
1451 | if (rbprev) | |
1452 | ret = rb_entry_arq(rbprev)->request; | |
1453 | ||
1454 | return ret; | |
1455 | } | |
1456 | ||
1457 | static struct request * | |
1458 | as_latter_request(request_queue_t *q, struct request *rq) | |
1459 | { | |
1460 | struct as_rq *arq = RQ_DATA(rq); | |
1461 | struct rb_node *rbnext = rb_next(&arq->rb_node); | |
1462 | struct request *ret = NULL; | |
1463 | ||
1464 | if (rbnext) | |
1465 | ret = rb_entry_arq(rbnext)->request; | |
1466 | ||
1467 | return ret; | |
1468 | } | |
1469 | ||
1470 | static int | |
1471 | as_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
1472 | { | |
1473 | struct as_data *ad = q->elevator->elevator_data; | |
1474 | sector_t rb_key = bio->bi_sector + bio_sectors(bio); | |
1475 | struct request *__rq; | |
1476 | int ret; | |
1477 | ||
1da177e4 LT |
1478 | /* |
1479 | * see if the merge hash can satisfy a back merge | |
1480 | */ | |
1481 | __rq = as_find_arq_hash(ad, bio->bi_sector); | |
1482 | if (__rq) { | |
1483 | BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); | |
1484 | ||
1485 | if (elv_rq_merge_ok(__rq, bio)) { | |
1486 | ret = ELEVATOR_BACK_MERGE; | |
1487 | goto out; | |
1488 | } | |
1489 | } | |
1490 | ||
1491 | /* | |
1492 | * check for front merge | |
1493 | */ | |
1494 | __rq = as_find_arq_rb(ad, rb_key, bio_data_dir(bio)); | |
1495 | if (__rq) { | |
1496 | BUG_ON(rb_key != rq_rb_key(__rq)); | |
1497 | ||
1498 | if (elv_rq_merge_ok(__rq, bio)) { | |
1499 | ret = ELEVATOR_FRONT_MERGE; | |
1500 | goto out; | |
1501 | } | |
1502 | } | |
1503 | ||
1504 | return ELEVATOR_NO_MERGE; | |
1505 | out: | |
1da177e4 LT |
1506 | if (ret) { |
1507 | if (rq_mergeable(__rq)) | |
1508 | as_hot_arq_hash(ad, RQ_DATA(__rq)); | |
1509 | } | |
1510 | *req = __rq; | |
1511 | return ret; | |
1512 | } | |
1513 | ||
1514 | static void as_merged_request(request_queue_t *q, struct request *req) | |
1515 | { | |
1516 | struct as_data *ad = q->elevator->elevator_data; | |
1517 | struct as_rq *arq = RQ_DATA(req); | |
1518 | ||
1519 | /* | |
1520 | * hash always needs to be repositioned, key is end sector | |
1521 | */ | |
1522 | as_del_arq_hash(arq); | |
1523 | as_add_arq_hash(ad, arq); | |
1524 | ||
1525 | /* | |
1526 | * if the merge was a front merge, we need to reposition request | |
1527 | */ | |
1528 | if (rq_rb_key(req) != arq->rb_key) { | |
1529 | struct as_rq *alias, *next_arq = NULL; | |
1530 | ||
1531 | if (ad->next_arq[arq->is_sync] == arq) | |
1532 | next_arq = as_find_next_arq(ad, arq); | |
1533 | ||
1534 | /* | |
1535 | * Note! We should really be moving any old aliased requests | |
1536 | * off this request and try to insert them into the rbtree. We | |
1537 | * currently don't bother. Ditto the next function. | |
1538 | */ | |
1539 | as_del_arq_rb(ad, arq); | |
1540 | if ((alias = as_add_arq_rb(ad, arq)) ) { | |
1541 | list_del_init(&arq->fifo); | |
1542 | as_add_aliased_request(ad, arq, alias); | |
1543 | if (next_arq) | |
1544 | ad->next_arq[arq->is_sync] = next_arq; | |
1545 | } | |
1546 | /* | |
1547 | * Note! At this stage of this and the next function, our next | |
1548 | * request may not be optimal - eg the request may have "grown" | |
1549 | * behind the disk head. We currently don't bother adjusting. | |
1550 | */ | |
1551 | } | |
1da177e4 LT |
1552 | } |
1553 | ||
1554 | static void | |
1555 | as_merged_requests(request_queue_t *q, struct request *req, | |
1556 | struct request *next) | |
1557 | { | |
1558 | struct as_data *ad = q->elevator->elevator_data; | |
1559 | struct as_rq *arq = RQ_DATA(req); | |
1560 | struct as_rq *anext = RQ_DATA(next); | |
1561 | ||
1562 | BUG_ON(!arq); | |
1563 | BUG_ON(!anext); | |
1564 | ||
1565 | /* | |
1566 | * reposition arq (this is the merged request) in hash, and in rbtree | |
1567 | * in case of a front merge | |
1568 | */ | |
1569 | as_del_arq_hash(arq); | |
1570 | as_add_arq_hash(ad, arq); | |
1571 | ||
1572 | if (rq_rb_key(req) != arq->rb_key) { | |
1573 | struct as_rq *alias, *next_arq = NULL; | |
1574 | ||
1575 | if (ad->next_arq[arq->is_sync] == arq) | |
1576 | next_arq = as_find_next_arq(ad, arq); | |
1577 | ||
1578 | as_del_arq_rb(ad, arq); | |
1579 | if ((alias = as_add_arq_rb(ad, arq)) ) { | |
1580 | list_del_init(&arq->fifo); | |
1581 | as_add_aliased_request(ad, arq, alias); | |
1582 | if (next_arq) | |
1583 | ad->next_arq[arq->is_sync] = next_arq; | |
1584 | } | |
1585 | } | |
1586 | ||
1587 | /* | |
1588 | * if anext expires before arq, assign its expire time to arq | |
1589 | * and move into anext position (anext will be deleted) in fifo | |
1590 | */ | |
1591 | if (!list_empty(&arq->fifo) && !list_empty(&anext->fifo)) { | |
1592 | if (time_before(anext->expires, arq->expires)) { | |
1593 | list_move(&arq->fifo, &anext->fifo); | |
1594 | arq->expires = anext->expires; | |
1595 | /* | |
1596 | * Don't copy here but swap, because when anext is | |
1597 | * removed below, it must contain the unused context | |
1598 | */ | |
1599 | swap_io_context(&arq->io_context, &anext->io_context); | |
1600 | } | |
1601 | } | |
1602 | ||
1603 | /* | |
1604 | * Transfer list of aliases | |
1605 | */ | |
1606 | while (!list_empty(&next->queuelist)) { | |
1607 | struct request *__rq = list_entry_rq(next->queuelist.next); | |
1608 | struct as_rq *__arq = RQ_DATA(__rq); | |
1609 | ||
1610 | list_move_tail(&__rq->queuelist, &req->queuelist); | |
1611 | ||
1612 | WARN_ON(__arq->state != AS_RQ_QUEUED); | |
1613 | } | |
1614 | ||
1615 | /* | |
1616 | * kill knowledge of next, this one is a goner | |
1617 | */ | |
1618 | as_remove_queued_request(q, next); | |
b4878f24 | 1619 | as_put_io_context(anext); |
1da177e4 LT |
1620 | |
1621 | anext->state = AS_RQ_MERGED; | |
1622 | } | |
1623 | ||
1624 | /* | |
1625 | * This is executed in a "deferred" process context, by kblockd. It calls the | |
1626 | * driver's request_fn so the driver can submit that request. | |
1627 | * | |
1628 | * IMPORTANT! This guy will reenter the elevator, so set up all queue global | |
1629 | * state before calling, and don't rely on any state over calls. | |
1630 | * | |
1631 | * FIXME! dispatch queue is not a queue at all! | |
1632 | */ | |
1633 | static void as_work_handler(void *data) | |
1634 | { | |
1635 | struct request_queue *q = data; | |
1636 | unsigned long flags; | |
1637 | ||
1638 | spin_lock_irqsave(q->queue_lock, flags); | |
b4878f24 | 1639 | if (!as_queue_empty(q)) |
1da177e4 LT |
1640 | q->request_fn(q); |
1641 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1642 | } | |
1643 | ||
1644 | static void as_put_request(request_queue_t *q, struct request *rq) | |
1645 | { | |
1646 | struct as_data *ad = q->elevator->elevator_data; | |
1647 | struct as_rq *arq = RQ_DATA(rq); | |
1648 | ||
1649 | if (!arq) { | |
1650 | WARN_ON(1); | |
1651 | return; | |
1652 | } | |
1653 | ||
b4878f24 JA |
1654 | if (unlikely(arq->state != AS_RQ_POSTSCHED && |
1655 | arq->state != AS_RQ_PRESCHED && | |
1656 | arq->state != AS_RQ_MERGED)) { | |
1da177e4 LT |
1657 | printk("arq->state %d\n", arq->state); |
1658 | WARN_ON(1); | |
1659 | } | |
1660 | ||
1661 | mempool_free(arq, ad->arq_pool); | |
1662 | rq->elevator_private = NULL; | |
1663 | } | |
1664 | ||
22e2c507 | 1665 | static int as_set_request(request_queue_t *q, struct request *rq, |
8267e268 | 1666 | struct bio *bio, gfp_t gfp_mask) |
1da177e4 LT |
1667 | { |
1668 | struct as_data *ad = q->elevator->elevator_data; | |
1669 | struct as_rq *arq = mempool_alloc(ad->arq_pool, gfp_mask); | |
1670 | ||
1671 | if (arq) { | |
1672 | memset(arq, 0, sizeof(*arq)); | |
1673 | RB_CLEAR(&arq->rb_node); | |
1674 | arq->request = rq; | |
1675 | arq->state = AS_RQ_PRESCHED; | |
1676 | arq->io_context = NULL; | |
1677 | INIT_LIST_HEAD(&arq->hash); | |
1678 | arq->on_hash = 0; | |
1679 | INIT_LIST_HEAD(&arq->fifo); | |
1680 | rq->elevator_private = arq; | |
1681 | return 0; | |
1682 | } | |
1683 | ||
1684 | return 1; | |
1685 | } | |
1686 | ||
22e2c507 | 1687 | static int as_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
1688 | { |
1689 | int ret = ELV_MQUEUE_MAY; | |
1690 | struct as_data *ad = q->elevator->elevator_data; | |
1691 | struct io_context *ioc; | |
1692 | if (ad->antic_status == ANTIC_WAIT_REQ || | |
1693 | ad->antic_status == ANTIC_WAIT_NEXT) { | |
1694 | ioc = as_get_io_context(); | |
1695 | if (ad->io_context == ioc) | |
1696 | ret = ELV_MQUEUE_MUST; | |
1697 | put_io_context(ioc); | |
1698 | } | |
1699 | ||
1700 | return ret; | |
1701 | } | |
1702 | ||
1703 | static void as_exit_queue(elevator_t *e) | |
1704 | { | |
1705 | struct as_data *ad = e->elevator_data; | |
1706 | ||
1707 | del_timer_sync(&ad->antic_timer); | |
1708 | kblockd_flush(); | |
1709 | ||
1710 | BUG_ON(!list_empty(&ad->fifo_list[REQ_SYNC])); | |
1711 | BUG_ON(!list_empty(&ad->fifo_list[REQ_ASYNC])); | |
1712 | ||
1713 | mempool_destroy(ad->arq_pool); | |
1714 | put_io_context(ad->io_context); | |
1715 | kfree(ad->hash); | |
1716 | kfree(ad); | |
1717 | } | |
1718 | ||
1719 | /* | |
1720 | * initialize elevator private data (as_data), and alloc a arq for | |
1721 | * each request on the free lists | |
1722 | */ | |
1723 | static int as_init_queue(request_queue_t *q, elevator_t *e) | |
1724 | { | |
1725 | struct as_data *ad; | |
1726 | int i; | |
1727 | ||
1728 | if (!arq_pool) | |
1729 | return -ENOMEM; | |
1730 | ||
1946089a | 1731 | ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node); |
1da177e4 LT |
1732 | if (!ad) |
1733 | return -ENOMEM; | |
1734 | memset(ad, 0, sizeof(*ad)); | |
1735 | ||
1736 | ad->q = q; /* Identify what queue the data belongs to */ | |
1737 | ||
1946089a CL |
1738 | ad->hash = kmalloc_node(sizeof(struct list_head)*AS_HASH_ENTRIES, |
1739 | GFP_KERNEL, q->node); | |
1da177e4 LT |
1740 | if (!ad->hash) { |
1741 | kfree(ad); | |
1742 | return -ENOMEM; | |
1743 | } | |
1744 | ||
1946089a CL |
1745 | ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
1746 | mempool_free_slab, arq_pool, q->node); | |
1da177e4 LT |
1747 | if (!ad->arq_pool) { |
1748 | kfree(ad->hash); | |
1749 | kfree(ad); | |
1750 | return -ENOMEM; | |
1751 | } | |
1752 | ||
1753 | /* anticipatory scheduling helpers */ | |
1754 | ad->antic_timer.function = as_antic_timeout; | |
1755 | ad->antic_timer.data = (unsigned long)q; | |
1756 | init_timer(&ad->antic_timer); | |
1757 | INIT_WORK(&ad->antic_work, as_work_handler, q); | |
1758 | ||
1759 | for (i = 0; i < AS_HASH_ENTRIES; i++) | |
1760 | INIT_LIST_HEAD(&ad->hash[i]); | |
1761 | ||
1762 | INIT_LIST_HEAD(&ad->fifo_list[REQ_SYNC]); | |
1763 | INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]); | |
1764 | ad->sort_list[REQ_SYNC] = RB_ROOT; | |
1765 | ad->sort_list[REQ_ASYNC] = RB_ROOT; | |
1da177e4 LT |
1766 | ad->fifo_expire[REQ_SYNC] = default_read_expire; |
1767 | ad->fifo_expire[REQ_ASYNC] = default_write_expire; | |
1768 | ad->antic_expire = default_antic_expire; | |
1769 | ad->batch_expire[REQ_SYNC] = default_read_batch_expire; | |
1770 | ad->batch_expire[REQ_ASYNC] = default_write_batch_expire; | |
1771 | e->elevator_data = ad; | |
1772 | ||
1773 | ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC]; | |
1774 | ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10; | |
1775 | if (ad->write_batch_count < 2) | |
1776 | ad->write_batch_count = 2; | |
1777 | ||
1778 | return 0; | |
1779 | } | |
1780 | ||
1781 | /* | |
1782 | * sysfs parts below | |
1783 | */ | |
1784 | struct as_fs_entry { | |
1785 | struct attribute attr; | |
1786 | ssize_t (*show)(struct as_data *, char *); | |
1787 | ssize_t (*store)(struct as_data *, const char *, size_t); | |
1788 | }; | |
1789 | ||
1790 | static ssize_t | |
1791 | as_var_show(unsigned int var, char *page) | |
1792 | { | |
1da177e4 LT |
1793 | return sprintf(page, "%d\n", var); |
1794 | } | |
1795 | ||
1796 | static ssize_t | |
1797 | as_var_store(unsigned long *var, const char *page, size_t count) | |
1798 | { | |
1da177e4 LT |
1799 | char *p = (char *) page; |
1800 | ||
c9b3ad67 | 1801 | *var = simple_strtoul(p, &p, 10); |
1da177e4 LT |
1802 | return count; |
1803 | } | |
1804 | ||
1805 | static ssize_t as_est_show(struct as_data *ad, char *page) | |
1806 | { | |
1807 | int pos = 0; | |
1808 | ||
1809 | pos += sprintf(page+pos, "%lu %% exit probability\n", 100*ad->exit_prob/256); | |
1810 | pos += sprintf(page+pos, "%lu ms new thinktime\n", ad->new_ttime_mean); | |
1811 | pos += sprintf(page+pos, "%llu sectors new seek distance\n", (unsigned long long)ad->new_seek_mean); | |
1812 | ||
1813 | return pos; | |
1814 | } | |
1815 | ||
1816 | #define SHOW_FUNCTION(__FUNC, __VAR) \ | |
1817 | static ssize_t __FUNC(struct as_data *ad, char *page) \ | |
1818 | { \ | |
1819 | return as_var_show(jiffies_to_msecs((__VAR)), (page)); \ | |
1820 | } | |
1821 | SHOW_FUNCTION(as_readexpire_show, ad->fifo_expire[REQ_SYNC]); | |
1822 | SHOW_FUNCTION(as_writeexpire_show, ad->fifo_expire[REQ_ASYNC]); | |
1823 | SHOW_FUNCTION(as_anticexpire_show, ad->antic_expire); | |
1824 | SHOW_FUNCTION(as_read_batchexpire_show, ad->batch_expire[REQ_SYNC]); | |
1825 | SHOW_FUNCTION(as_write_batchexpire_show, ad->batch_expire[REQ_ASYNC]); | |
1826 | #undef SHOW_FUNCTION | |
1827 | ||
1828 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ | |
1829 | static ssize_t __FUNC(struct as_data *ad, const char *page, size_t count) \ | |
1830 | { \ | |
1831 | int ret = as_var_store(__PTR, (page), count); \ | |
1832 | if (*(__PTR) < (MIN)) \ | |
1833 | *(__PTR) = (MIN); \ | |
1834 | else if (*(__PTR) > (MAX)) \ | |
1835 | *(__PTR) = (MAX); \ | |
1836 | *(__PTR) = msecs_to_jiffies(*(__PTR)); \ | |
1837 | return ret; \ | |
1838 | } | |
1839 | STORE_FUNCTION(as_readexpire_store, &ad->fifo_expire[REQ_SYNC], 0, INT_MAX); | |
1840 | STORE_FUNCTION(as_writeexpire_store, &ad->fifo_expire[REQ_ASYNC], 0, INT_MAX); | |
1841 | STORE_FUNCTION(as_anticexpire_store, &ad->antic_expire, 0, INT_MAX); | |
1842 | STORE_FUNCTION(as_read_batchexpire_store, | |
1843 | &ad->batch_expire[REQ_SYNC], 0, INT_MAX); | |
1844 | STORE_FUNCTION(as_write_batchexpire_store, | |
1845 | &ad->batch_expire[REQ_ASYNC], 0, INT_MAX); | |
1846 | #undef STORE_FUNCTION | |
1847 | ||
1848 | static struct as_fs_entry as_est_entry = { | |
1849 | .attr = {.name = "est_time", .mode = S_IRUGO }, | |
1850 | .show = as_est_show, | |
1851 | }; | |
1852 | static struct as_fs_entry as_readexpire_entry = { | |
1853 | .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR }, | |
1854 | .show = as_readexpire_show, | |
1855 | .store = as_readexpire_store, | |
1856 | }; | |
1857 | static struct as_fs_entry as_writeexpire_entry = { | |
1858 | .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR }, | |
1859 | .show = as_writeexpire_show, | |
1860 | .store = as_writeexpire_store, | |
1861 | }; | |
1862 | static struct as_fs_entry as_anticexpire_entry = { | |
1863 | .attr = {.name = "antic_expire", .mode = S_IRUGO | S_IWUSR }, | |
1864 | .show = as_anticexpire_show, | |
1865 | .store = as_anticexpire_store, | |
1866 | }; | |
1867 | static struct as_fs_entry as_read_batchexpire_entry = { | |
1868 | .attr = {.name = "read_batch_expire", .mode = S_IRUGO | S_IWUSR }, | |
1869 | .show = as_read_batchexpire_show, | |
1870 | .store = as_read_batchexpire_store, | |
1871 | }; | |
1872 | static struct as_fs_entry as_write_batchexpire_entry = { | |
1873 | .attr = {.name = "write_batch_expire", .mode = S_IRUGO | S_IWUSR }, | |
1874 | .show = as_write_batchexpire_show, | |
1875 | .store = as_write_batchexpire_store, | |
1876 | }; | |
1877 | ||
1878 | static struct attribute *default_attrs[] = { | |
1879 | &as_est_entry.attr, | |
1880 | &as_readexpire_entry.attr, | |
1881 | &as_writeexpire_entry.attr, | |
1882 | &as_anticexpire_entry.attr, | |
1883 | &as_read_batchexpire_entry.attr, | |
1884 | &as_write_batchexpire_entry.attr, | |
1885 | NULL, | |
1886 | }; | |
1887 | ||
1888 | #define to_as(atr) container_of((atr), struct as_fs_entry, attr) | |
1889 | ||
1890 | static ssize_t | |
1891 | as_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1892 | { | |
1893 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
1894 | struct as_fs_entry *entry = to_as(attr); | |
1895 | ||
1896 | if (!entry->show) | |
6c1852a0 | 1897 | return -EIO; |
1da177e4 LT |
1898 | |
1899 | return entry->show(e->elevator_data, page); | |
1900 | } | |
1901 | ||
1902 | static ssize_t | |
1903 | as_attr_store(struct kobject *kobj, struct attribute *attr, | |
1904 | const char *page, size_t length) | |
1905 | { | |
1906 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
1907 | struct as_fs_entry *entry = to_as(attr); | |
1908 | ||
1909 | if (!entry->store) | |
6c1852a0 | 1910 | return -EIO; |
1da177e4 LT |
1911 | |
1912 | return entry->store(e->elevator_data, page, length); | |
1913 | } | |
1914 | ||
1915 | static struct sysfs_ops as_sysfs_ops = { | |
1916 | .show = as_attr_show, | |
1917 | .store = as_attr_store, | |
1918 | }; | |
1919 | ||
1920 | static struct kobj_type as_ktype = { | |
1921 | .sysfs_ops = &as_sysfs_ops, | |
1922 | .default_attrs = default_attrs, | |
1923 | }; | |
1924 | ||
1925 | static struct elevator_type iosched_as = { | |
1926 | .ops = { | |
1927 | .elevator_merge_fn = as_merge, | |
1928 | .elevator_merged_fn = as_merged_request, | |
1929 | .elevator_merge_req_fn = as_merged_requests, | |
b4878f24 JA |
1930 | .elevator_dispatch_fn = as_dispatch_request, |
1931 | .elevator_add_req_fn = as_add_request, | |
1932 | .elevator_activate_req_fn = as_activate_request, | |
1da177e4 LT |
1933 | .elevator_deactivate_req_fn = as_deactivate_request, |
1934 | .elevator_queue_empty_fn = as_queue_empty, | |
1935 | .elevator_completed_req_fn = as_completed_request, | |
1936 | .elevator_former_req_fn = as_former_request, | |
1937 | .elevator_latter_req_fn = as_latter_request, | |
1938 | .elevator_set_req_fn = as_set_request, | |
1939 | .elevator_put_req_fn = as_put_request, | |
1940 | .elevator_may_queue_fn = as_may_queue, | |
1941 | .elevator_init_fn = as_init_queue, | |
1942 | .elevator_exit_fn = as_exit_queue, | |
1943 | }, | |
1944 | ||
1945 | .elevator_ktype = &as_ktype, | |
1946 | .elevator_name = "anticipatory", | |
1947 | .elevator_owner = THIS_MODULE, | |
1948 | }; | |
1949 | ||
1950 | static int __init as_init(void) | |
1951 | { | |
1952 | int ret; | |
1953 | ||
1954 | arq_pool = kmem_cache_create("as_arq", sizeof(struct as_rq), | |
1955 | 0, 0, NULL, NULL); | |
1956 | if (!arq_pool) | |
1957 | return -ENOMEM; | |
1958 | ||
1959 | ret = elv_register(&iosched_as); | |
1960 | if (!ret) { | |
1961 | /* | |
1962 | * don't allow AS to get unregistered, since we would have | |
1963 | * to browse all tasks in the system and release their | |
1964 | * as_io_context first | |
1965 | */ | |
1966 | __module_get(THIS_MODULE); | |
1967 | return 0; | |
1968 | } | |
1969 | ||
1970 | kmem_cache_destroy(arq_pool); | |
1971 | return ret; | |
1972 | } | |
1973 | ||
1974 | static void __exit as_exit(void) | |
1975 | { | |
1da177e4 | 1976 | elv_unregister(&iosched_as); |
83521d3e | 1977 | kmem_cache_destroy(arq_pool); |
1da177e4 LT |
1978 | } |
1979 | ||
1980 | module_init(as_init); | |
1981 | module_exit(as_exit); | |
1982 | ||
1983 | MODULE_AUTHOR("Nick Piggin"); | |
1984 | MODULE_LICENSE("GPL"); | |
1985 | MODULE_DESCRIPTION("anticipatory IO scheduler"); |