Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Anticipatory & deadline i/o scheduler. |
3 | * | |
4 | * Copyright (C) 2002 Jens Axboe <axboe@suse.de> | |
f5b3db00 | 5 | * Nick Piggin <nickpiggin@yahoo.com.au> |
1da177e4 LT |
6 | * |
7 | */ | |
8 | #include <linux/kernel.h> | |
9 | #include <linux/fs.h> | |
10 | #include <linux/blkdev.h> | |
11 | #include <linux/elevator.h> | |
12 | #include <linux/bio.h> | |
13 | #include <linux/config.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/compiler.h> | |
18 | #include <linux/hash.h> | |
19 | #include <linux/rbtree.h> | |
20 | #include <linux/interrupt.h> | |
21 | ||
22 | #define REQ_SYNC 1 | |
23 | #define REQ_ASYNC 0 | |
24 | ||
25 | /* | |
26 | * See Documentation/block/as-iosched.txt | |
27 | */ | |
28 | ||
29 | /* | |
30 | * max time before a read is submitted. | |
31 | */ | |
32 | #define default_read_expire (HZ / 8) | |
33 | ||
34 | /* | |
35 | * ditto for writes, these limits are not hard, even | |
36 | * if the disk is capable of satisfying them. | |
37 | */ | |
38 | #define default_write_expire (HZ / 4) | |
39 | ||
40 | /* | |
41 | * read_batch_expire describes how long we will allow a stream of reads to | |
42 | * persist before looking to see whether it is time to switch over to writes. | |
43 | */ | |
44 | #define default_read_batch_expire (HZ / 2) | |
45 | ||
46 | /* | |
47 | * write_batch_expire describes how long we want a stream of writes to run for. | |
48 | * This is not a hard limit, but a target we set for the auto-tuning thingy. | |
49 | * See, the problem is: we can send a lot of writes to disk cache / TCQ in | |
50 | * a short amount of time... | |
51 | */ | |
52 | #define default_write_batch_expire (HZ / 8) | |
53 | ||
54 | /* | |
55 | * max time we may wait to anticipate a read (default around 6ms) | |
56 | */ | |
57 | #define default_antic_expire ((HZ / 150) ? HZ / 150 : 1) | |
58 | ||
59 | /* | |
60 | * Keep track of up to 20ms thinktimes. We can go as big as we like here, | |
61 | * however huge values tend to interfere and not decay fast enough. A program | |
62 | * might be in a non-io phase of operation. Waiting on user input for example, | |
63 | * or doing a lengthy computation. A small penalty can be justified there, and | |
64 | * will still catch out those processes that constantly have large thinktimes. | |
65 | */ | |
66 | #define MAX_THINKTIME (HZ/50UL) | |
67 | ||
68 | /* Bits in as_io_context.state */ | |
69 | enum as_io_states { | |
f5b3db00 | 70 | AS_TASK_RUNNING=0, /* Process has not exited */ |
1da177e4 LT |
71 | AS_TASK_IOSTARTED, /* Process has started some IO */ |
72 | AS_TASK_IORUNNING, /* Process has completed some IO */ | |
73 | }; | |
74 | ||
75 | enum anticipation_status { | |
76 | ANTIC_OFF=0, /* Not anticipating (normal operation) */ | |
77 | ANTIC_WAIT_REQ, /* The last read has not yet completed */ | |
78 | ANTIC_WAIT_NEXT, /* Currently anticipating a request vs | |
79 | last read (which has completed) */ | |
80 | ANTIC_FINISHED, /* Anticipating but have found a candidate | |
81 | * or timed out */ | |
82 | }; | |
83 | ||
84 | struct as_data { | |
85 | /* | |
86 | * run time data | |
87 | */ | |
88 | ||
89 | struct request_queue *q; /* the "owner" queue */ | |
90 | ||
91 | /* | |
92 | * requests (as_rq s) are present on both sort_list and fifo_list | |
93 | */ | |
94 | struct rb_root sort_list[2]; | |
95 | struct list_head fifo_list[2]; | |
96 | ||
97 | struct as_rq *next_arq[2]; /* next in sort order */ | |
98 | sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */ | |
1da177e4 LT |
99 | struct list_head *hash; /* request hash */ |
100 | ||
101 | unsigned long exit_prob; /* probability a task will exit while | |
102 | being waited on */ | |
f5b3db00 NP |
103 | unsigned long exit_no_coop; /* probablility an exited task will |
104 | not be part of a later cooperating | |
105 | request */ | |
1da177e4 LT |
106 | unsigned long new_ttime_total; /* mean thinktime on new proc */ |
107 | unsigned long new_ttime_mean; | |
108 | u64 new_seek_total; /* mean seek on new proc */ | |
109 | sector_t new_seek_mean; | |
110 | ||
111 | unsigned long current_batch_expires; | |
112 | unsigned long last_check_fifo[2]; | |
113 | int changed_batch; /* 1: waiting for old batch to end */ | |
114 | int new_batch; /* 1: waiting on first read complete */ | |
115 | int batch_data_dir; /* current batch REQ_SYNC / REQ_ASYNC */ | |
116 | int write_batch_count; /* max # of reqs in a write batch */ | |
117 | int current_write_count; /* how many requests left this batch */ | |
118 | int write_batch_idled; /* has the write batch gone idle? */ | |
119 | mempool_t *arq_pool; | |
120 | ||
121 | enum anticipation_status antic_status; | |
122 | unsigned long antic_start; /* jiffies: when it started */ | |
123 | struct timer_list antic_timer; /* anticipatory scheduling timer */ | |
124 | struct work_struct antic_work; /* Deferred unplugging */ | |
125 | struct io_context *io_context; /* Identify the expected process */ | |
126 | int ioc_finished; /* IO associated with io_context is finished */ | |
127 | int nr_dispatched; | |
128 | ||
129 | /* | |
130 | * settings that change how the i/o scheduler behaves | |
131 | */ | |
132 | unsigned long fifo_expire[2]; | |
133 | unsigned long batch_expire[2]; | |
134 | unsigned long antic_expire; | |
135 | }; | |
136 | ||
137 | #define list_entry_fifo(ptr) list_entry((ptr), struct as_rq, fifo) | |
138 | ||
139 | /* | |
140 | * per-request data. | |
141 | */ | |
142 | enum arq_state { | |
143 | AS_RQ_NEW=0, /* New - not referenced and not on any lists */ | |
144 | AS_RQ_QUEUED, /* In the request queue. It belongs to the | |
145 | scheduler */ | |
146 | AS_RQ_DISPATCHED, /* On the dispatch list. It belongs to the | |
147 | driver now */ | |
148 | AS_RQ_PRESCHED, /* Debug poisoning for requests being used */ | |
149 | AS_RQ_REMOVED, | |
150 | AS_RQ_MERGED, | |
151 | AS_RQ_POSTSCHED, /* when they shouldn't be */ | |
152 | }; | |
153 | ||
154 | struct as_rq { | |
155 | /* | |
156 | * rbtree index, key is the starting offset | |
157 | */ | |
158 | struct rb_node rb_node; | |
159 | sector_t rb_key; | |
160 | ||
161 | struct request *request; | |
162 | ||
163 | struct io_context *io_context; /* The submitting task */ | |
164 | ||
165 | /* | |
166 | * request hash, key is the ending offset (for back merge lookup) | |
167 | */ | |
168 | struct list_head hash; | |
169 | unsigned int on_hash; | |
170 | ||
171 | /* | |
172 | * expire fifo | |
173 | */ | |
174 | struct list_head fifo; | |
175 | unsigned long expires; | |
176 | ||
177 | unsigned int is_sync; | |
178 | enum arq_state state; | |
179 | }; | |
180 | ||
181 | #define RQ_DATA(rq) ((struct as_rq *) (rq)->elevator_private) | |
182 | ||
183 | static kmem_cache_t *arq_pool; | |
184 | ||
334e94de AV |
185 | static atomic_t ioc_count = ATOMIC_INIT(0); |
186 | static struct completion *ioc_gone; | |
187 | ||
ef9be1d3 TH |
188 | static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq); |
189 | static void as_antic_stop(struct as_data *ad); | |
190 | ||
1da177e4 LT |
191 | /* |
192 | * IO Context helper functions | |
193 | */ | |
194 | ||
195 | /* Called to deallocate the as_io_context */ | |
196 | static void free_as_io_context(struct as_io_context *aic) | |
197 | { | |
198 | kfree(aic); | |
334e94de AV |
199 | if (atomic_dec_and_test(&ioc_count) && ioc_gone) |
200 | complete(ioc_gone); | |
1da177e4 LT |
201 | } |
202 | ||
e17a9489 AV |
203 | static void as_trim(struct io_context *ioc) |
204 | { | |
334e94de AV |
205 | if (ioc->aic) |
206 | free_as_io_context(ioc->aic); | |
e17a9489 AV |
207 | ioc->aic = NULL; |
208 | } | |
209 | ||
1da177e4 LT |
210 | /* Called when the task exits */ |
211 | static void exit_as_io_context(struct as_io_context *aic) | |
212 | { | |
213 | WARN_ON(!test_bit(AS_TASK_RUNNING, &aic->state)); | |
214 | clear_bit(AS_TASK_RUNNING, &aic->state); | |
215 | } | |
216 | ||
217 | static struct as_io_context *alloc_as_io_context(void) | |
218 | { | |
219 | struct as_io_context *ret; | |
220 | ||
221 | ret = kmalloc(sizeof(*ret), GFP_ATOMIC); | |
222 | if (ret) { | |
223 | ret->dtor = free_as_io_context; | |
224 | ret->exit = exit_as_io_context; | |
225 | ret->state = 1 << AS_TASK_RUNNING; | |
226 | atomic_set(&ret->nr_queued, 0); | |
227 | atomic_set(&ret->nr_dispatched, 0); | |
228 | spin_lock_init(&ret->lock); | |
229 | ret->ttime_total = 0; | |
230 | ret->ttime_samples = 0; | |
231 | ret->ttime_mean = 0; | |
232 | ret->seek_total = 0; | |
233 | ret->seek_samples = 0; | |
234 | ret->seek_mean = 0; | |
334e94de | 235 | atomic_inc(&ioc_count); |
1da177e4 LT |
236 | } |
237 | ||
238 | return ret; | |
239 | } | |
240 | ||
241 | /* | |
242 | * If the current task has no AS IO context then create one and initialise it. | |
243 | * Then take a ref on the task's io context and return it. | |
244 | */ | |
245 | static struct io_context *as_get_io_context(void) | |
246 | { | |
247 | struct io_context *ioc = get_io_context(GFP_ATOMIC); | |
248 | if (ioc && !ioc->aic) { | |
249 | ioc->aic = alloc_as_io_context(); | |
250 | if (!ioc->aic) { | |
251 | put_io_context(ioc); | |
252 | ioc = NULL; | |
253 | } | |
254 | } | |
255 | return ioc; | |
256 | } | |
257 | ||
b4878f24 JA |
258 | static void as_put_io_context(struct as_rq *arq) |
259 | { | |
260 | struct as_io_context *aic; | |
261 | ||
262 | if (unlikely(!arq->io_context)) | |
263 | return; | |
264 | ||
265 | aic = arq->io_context->aic; | |
266 | ||
267 | if (arq->is_sync == REQ_SYNC && aic) { | |
268 | spin_lock(&aic->lock); | |
269 | set_bit(AS_TASK_IORUNNING, &aic->state); | |
270 | aic->last_end_request = jiffies; | |
271 | spin_unlock(&aic->lock); | |
272 | } | |
273 | ||
274 | put_io_context(arq->io_context); | |
275 | } | |
276 | ||
1da177e4 LT |
277 | /* |
278 | * the back merge hash support functions | |
279 | */ | |
280 | static const int as_hash_shift = 6; | |
281 | #define AS_HASH_BLOCK(sec) ((sec) >> 3) | |
282 | #define AS_HASH_FN(sec) (hash_long(AS_HASH_BLOCK((sec)), as_hash_shift)) | |
283 | #define AS_HASH_ENTRIES (1 << as_hash_shift) | |
284 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
285 | #define list_entry_hash(ptr) list_entry((ptr), struct as_rq, hash) | |
286 | ||
287 | static inline void __as_del_arq_hash(struct as_rq *arq) | |
288 | { | |
289 | arq->on_hash = 0; | |
290 | list_del_init(&arq->hash); | |
291 | } | |
292 | ||
293 | static inline void as_del_arq_hash(struct as_rq *arq) | |
294 | { | |
295 | if (arq->on_hash) | |
296 | __as_del_arq_hash(arq); | |
297 | } | |
298 | ||
1da177e4 LT |
299 | static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq) |
300 | { | |
301 | struct request *rq = arq->request; | |
302 | ||
303 | BUG_ON(arq->on_hash); | |
304 | ||
305 | arq->on_hash = 1; | |
306 | list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]); | |
307 | } | |
308 | ||
309 | /* | |
310 | * move hot entry to front of chain | |
311 | */ | |
312 | static inline void as_hot_arq_hash(struct as_data *ad, struct as_rq *arq) | |
313 | { | |
314 | struct request *rq = arq->request; | |
315 | struct list_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))]; | |
316 | ||
317 | if (!arq->on_hash) { | |
318 | WARN_ON(1); | |
319 | return; | |
320 | } | |
321 | ||
322 | if (arq->hash.prev != head) { | |
323 | list_del(&arq->hash); | |
324 | list_add(&arq->hash, head); | |
325 | } | |
326 | } | |
327 | ||
328 | static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset) | |
329 | { | |
330 | struct list_head *hash_list = &ad->hash[AS_HASH_FN(offset)]; | |
331 | struct list_head *entry, *next = hash_list->next; | |
332 | ||
333 | while ((entry = next) != hash_list) { | |
334 | struct as_rq *arq = list_entry_hash(entry); | |
335 | struct request *__rq = arq->request; | |
336 | ||
337 | next = entry->next; | |
338 | ||
339 | BUG_ON(!arq->on_hash); | |
340 | ||
341 | if (!rq_mergeable(__rq)) { | |
98b11471 | 342 | as_del_arq_hash(arq); |
1da177e4 LT |
343 | continue; |
344 | } | |
345 | ||
346 | if (rq_hash_key(__rq) == offset) | |
347 | return __rq; | |
348 | } | |
349 | ||
350 | return NULL; | |
351 | } | |
352 | ||
353 | /* | |
354 | * rb tree support functions | |
355 | */ | |
356 | #define RB_NONE (2) | |
357 | #define RB_EMPTY(root) ((root)->rb_node == NULL) | |
358 | #define ON_RB(node) ((node)->rb_color != RB_NONE) | |
359 | #define RB_CLEAR(node) ((node)->rb_color = RB_NONE) | |
360 | #define rb_entry_arq(node) rb_entry((node), struct as_rq, rb_node) | |
361 | #define ARQ_RB_ROOT(ad, arq) (&(ad)->sort_list[(arq)->is_sync]) | |
362 | #define rq_rb_key(rq) (rq)->sector | |
363 | ||
364 | /* | |
365 | * as_find_first_arq finds the first (lowest sector numbered) request | |
366 | * for the specified data_dir. Used to sweep back to the start of the disk | |
367 | * (1-way elevator) after we process the last (highest sector) request. | |
368 | */ | |
369 | static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir) | |
370 | { | |
371 | struct rb_node *n = ad->sort_list[data_dir].rb_node; | |
372 | ||
373 | if (n == NULL) | |
374 | return NULL; | |
375 | ||
376 | for (;;) { | |
377 | if (n->rb_left == NULL) | |
378 | return rb_entry_arq(n); | |
379 | ||
380 | n = n->rb_left; | |
381 | } | |
382 | } | |
383 | ||
384 | /* | |
385 | * Add the request to the rb tree if it is unique. If there is an alias (an | |
386 | * existing request against the same sector), which can happen when using | |
387 | * direct IO, then return the alias. | |
388 | */ | |
ef9be1d3 | 389 | static struct as_rq *__as_add_arq_rb(struct as_data *ad, struct as_rq *arq) |
1da177e4 LT |
390 | { |
391 | struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node; | |
392 | struct rb_node *parent = NULL; | |
393 | struct as_rq *__arq; | |
394 | struct request *rq = arq->request; | |
395 | ||
396 | arq->rb_key = rq_rb_key(rq); | |
397 | ||
398 | while (*p) { | |
399 | parent = *p; | |
400 | __arq = rb_entry_arq(parent); | |
401 | ||
402 | if (arq->rb_key < __arq->rb_key) | |
403 | p = &(*p)->rb_left; | |
404 | else if (arq->rb_key > __arq->rb_key) | |
405 | p = &(*p)->rb_right; | |
406 | else | |
407 | return __arq; | |
408 | } | |
409 | ||
410 | rb_link_node(&arq->rb_node, parent, p); | |
411 | rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); | |
412 | ||
413 | return NULL; | |
414 | } | |
415 | ||
ef9be1d3 TH |
416 | static void as_add_arq_rb(struct as_data *ad, struct as_rq *arq) |
417 | { | |
418 | struct as_rq *alias; | |
419 | ||
420 | while ((unlikely(alias = __as_add_arq_rb(ad, arq)))) { | |
421 | as_move_to_dispatch(ad, alias); | |
422 | as_antic_stop(ad); | |
423 | } | |
424 | } | |
425 | ||
1da177e4 LT |
426 | static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq) |
427 | { | |
428 | if (!ON_RB(&arq->rb_node)) { | |
429 | WARN_ON(1); | |
430 | return; | |
431 | } | |
432 | ||
433 | rb_erase(&arq->rb_node, ARQ_RB_ROOT(ad, arq)); | |
434 | RB_CLEAR(&arq->rb_node); | |
435 | } | |
436 | ||
437 | static struct request * | |
438 | as_find_arq_rb(struct as_data *ad, sector_t sector, int data_dir) | |
439 | { | |
440 | struct rb_node *n = ad->sort_list[data_dir].rb_node; | |
441 | struct as_rq *arq; | |
442 | ||
443 | while (n) { | |
444 | arq = rb_entry_arq(n); | |
445 | ||
446 | if (sector < arq->rb_key) | |
447 | n = n->rb_left; | |
448 | else if (sector > arq->rb_key) | |
449 | n = n->rb_right; | |
450 | else | |
451 | return arq->request; | |
452 | } | |
453 | ||
454 | return NULL; | |
455 | } | |
456 | ||
457 | /* | |
458 | * IO Scheduler proper | |
459 | */ | |
460 | ||
461 | #define MAXBACK (1024 * 1024) /* | |
462 | * Maximum distance the disk will go backward | |
463 | * for a request. | |
464 | */ | |
465 | ||
466 | #define BACK_PENALTY 2 | |
467 | ||
468 | /* | |
469 | * as_choose_req selects the preferred one of two requests of the same data_dir | |
470 | * ignoring time - eg. timeouts, which is the job of as_dispatch_request | |
471 | */ | |
472 | static struct as_rq * | |
473 | as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2) | |
474 | { | |
475 | int data_dir; | |
476 | sector_t last, s1, s2, d1, d2; | |
477 | int r1_wrap=0, r2_wrap=0; /* requests are behind the disk head */ | |
478 | const sector_t maxback = MAXBACK; | |
479 | ||
480 | if (arq1 == NULL || arq1 == arq2) | |
481 | return arq2; | |
482 | if (arq2 == NULL) | |
483 | return arq1; | |
484 | ||
485 | data_dir = arq1->is_sync; | |
486 | ||
487 | last = ad->last_sector[data_dir]; | |
488 | s1 = arq1->request->sector; | |
489 | s2 = arq2->request->sector; | |
490 | ||
491 | BUG_ON(data_dir != arq2->is_sync); | |
492 | ||
493 | /* | |
494 | * Strict one way elevator _except_ in the case where we allow | |
495 | * short backward seeks which are biased as twice the cost of a | |
496 | * similar forward seek. | |
497 | */ | |
498 | if (s1 >= last) | |
499 | d1 = s1 - last; | |
500 | else if (s1+maxback >= last) | |
501 | d1 = (last - s1)*BACK_PENALTY; | |
502 | else { | |
503 | r1_wrap = 1; | |
504 | d1 = 0; /* shut up, gcc */ | |
505 | } | |
506 | ||
507 | if (s2 >= last) | |
508 | d2 = s2 - last; | |
509 | else if (s2+maxback >= last) | |
510 | d2 = (last - s2)*BACK_PENALTY; | |
511 | else { | |
512 | r2_wrap = 1; | |
513 | d2 = 0; | |
514 | } | |
515 | ||
516 | /* Found required data */ | |
517 | if (!r1_wrap && r2_wrap) | |
518 | return arq1; | |
519 | else if (!r2_wrap && r1_wrap) | |
520 | return arq2; | |
521 | else if (r1_wrap && r2_wrap) { | |
522 | /* both behind the head */ | |
523 | if (s1 <= s2) | |
524 | return arq1; | |
525 | else | |
526 | return arq2; | |
527 | } | |
528 | ||
529 | /* Both requests in front of the head */ | |
530 | if (d1 < d2) | |
531 | return arq1; | |
532 | else if (d2 < d1) | |
533 | return arq2; | |
534 | else { | |
535 | if (s1 >= s2) | |
536 | return arq1; | |
537 | else | |
538 | return arq2; | |
539 | } | |
540 | } | |
541 | ||
542 | /* | |
543 | * as_find_next_arq finds the next request after @prev in elevator order. | |
544 | * this with as_choose_req form the basis for how the scheduler chooses | |
545 | * what request to process next. Anticipation works on top of this. | |
546 | */ | |
547 | static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *last) | |
548 | { | |
549 | const int data_dir = last->is_sync; | |
550 | struct as_rq *ret; | |
551 | struct rb_node *rbnext = rb_next(&last->rb_node); | |
552 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
553 | struct as_rq *arq_next, *arq_prev; | |
554 | ||
555 | BUG_ON(!ON_RB(&last->rb_node)); | |
556 | ||
557 | if (rbprev) | |
558 | arq_prev = rb_entry_arq(rbprev); | |
559 | else | |
560 | arq_prev = NULL; | |
561 | ||
562 | if (rbnext) | |
563 | arq_next = rb_entry_arq(rbnext); | |
564 | else { | |
565 | arq_next = as_find_first_arq(ad, data_dir); | |
566 | if (arq_next == last) | |
567 | arq_next = NULL; | |
568 | } | |
569 | ||
570 | ret = as_choose_req(ad, arq_next, arq_prev); | |
571 | ||
572 | return ret; | |
573 | } | |
574 | ||
575 | /* | |
576 | * anticipatory scheduling functions follow | |
577 | */ | |
578 | ||
579 | /* | |
580 | * as_antic_expired tells us when we have anticipated too long. | |
581 | * The funny "absolute difference" math on the elapsed time is to handle | |
582 | * jiffy wraps, and disks which have been idle for 0x80000000 jiffies. | |
583 | */ | |
584 | static int as_antic_expired(struct as_data *ad) | |
585 | { | |
586 | long delta_jif; | |
587 | ||
588 | delta_jif = jiffies - ad->antic_start; | |
589 | if (unlikely(delta_jif < 0)) | |
590 | delta_jif = -delta_jif; | |
591 | if (delta_jif < ad->antic_expire) | |
592 | return 0; | |
593 | ||
594 | return 1; | |
595 | } | |
596 | ||
597 | /* | |
598 | * as_antic_waitnext starts anticipating that a nice request will soon be | |
599 | * submitted. See also as_antic_waitreq | |
600 | */ | |
601 | static void as_antic_waitnext(struct as_data *ad) | |
602 | { | |
603 | unsigned long timeout; | |
604 | ||
605 | BUG_ON(ad->antic_status != ANTIC_OFF | |
606 | && ad->antic_status != ANTIC_WAIT_REQ); | |
607 | ||
608 | timeout = ad->antic_start + ad->antic_expire; | |
609 | ||
610 | mod_timer(&ad->antic_timer, timeout); | |
611 | ||
612 | ad->antic_status = ANTIC_WAIT_NEXT; | |
613 | } | |
614 | ||
615 | /* | |
616 | * as_antic_waitreq starts anticipating. We don't start timing the anticipation | |
617 | * until the request that we're anticipating on has finished. This means we | |
618 | * are timing from when the candidate process wakes up hopefully. | |
619 | */ | |
620 | static void as_antic_waitreq(struct as_data *ad) | |
621 | { | |
622 | BUG_ON(ad->antic_status == ANTIC_FINISHED); | |
623 | if (ad->antic_status == ANTIC_OFF) { | |
624 | if (!ad->io_context || ad->ioc_finished) | |
625 | as_antic_waitnext(ad); | |
626 | else | |
627 | ad->antic_status = ANTIC_WAIT_REQ; | |
628 | } | |
629 | } | |
630 | ||
631 | /* | |
632 | * This is called directly by the functions in this file to stop anticipation. | |
633 | * We kill the timer and schedule a call to the request_fn asap. | |
634 | */ | |
635 | static void as_antic_stop(struct as_data *ad) | |
636 | { | |
637 | int status = ad->antic_status; | |
638 | ||
639 | if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) { | |
640 | if (status == ANTIC_WAIT_NEXT) | |
641 | del_timer(&ad->antic_timer); | |
642 | ad->antic_status = ANTIC_FINISHED; | |
643 | /* see as_work_handler */ | |
644 | kblockd_schedule_work(&ad->antic_work); | |
645 | } | |
646 | } | |
647 | ||
648 | /* | |
649 | * as_antic_timeout is the timer function set by as_antic_waitnext. | |
650 | */ | |
651 | static void as_antic_timeout(unsigned long data) | |
652 | { | |
653 | struct request_queue *q = (struct request_queue *)data; | |
654 | struct as_data *ad = q->elevator->elevator_data; | |
655 | unsigned long flags; | |
656 | ||
657 | spin_lock_irqsave(q->queue_lock, flags); | |
658 | if (ad->antic_status == ANTIC_WAIT_REQ | |
659 | || ad->antic_status == ANTIC_WAIT_NEXT) { | |
660 | struct as_io_context *aic = ad->io_context->aic; | |
661 | ||
662 | ad->antic_status = ANTIC_FINISHED; | |
663 | kblockd_schedule_work(&ad->antic_work); | |
664 | ||
665 | if (aic->ttime_samples == 0) { | |
f5b3db00 | 666 | /* process anticipated on has exited or timed out*/ |
1da177e4 LT |
667 | ad->exit_prob = (7*ad->exit_prob + 256)/8; |
668 | } | |
f5b3db00 NP |
669 | if (!test_bit(AS_TASK_RUNNING, &aic->state)) { |
670 | /* process not "saved" by a cooperating request */ | |
671 | ad->exit_no_coop = (7*ad->exit_no_coop + 256)/8; | |
672 | } | |
1da177e4 LT |
673 | } |
674 | spin_unlock_irqrestore(q->queue_lock, flags); | |
675 | } | |
676 | ||
f5b3db00 NP |
677 | static void as_update_thinktime(struct as_data *ad, struct as_io_context *aic, |
678 | unsigned long ttime) | |
679 | { | |
680 | /* fixed point: 1.0 == 1<<8 */ | |
681 | if (aic->ttime_samples == 0) { | |
682 | ad->new_ttime_total = (7*ad->new_ttime_total + 256*ttime) / 8; | |
683 | ad->new_ttime_mean = ad->new_ttime_total / 256; | |
684 | ||
685 | ad->exit_prob = (7*ad->exit_prob)/8; | |
686 | } | |
687 | aic->ttime_samples = (7*aic->ttime_samples + 256) / 8; | |
688 | aic->ttime_total = (7*aic->ttime_total + 256*ttime) / 8; | |
689 | aic->ttime_mean = (aic->ttime_total + 128) / aic->ttime_samples; | |
690 | } | |
691 | ||
692 | static void as_update_seekdist(struct as_data *ad, struct as_io_context *aic, | |
693 | sector_t sdist) | |
694 | { | |
695 | u64 total; | |
696 | ||
697 | if (aic->seek_samples == 0) { | |
698 | ad->new_seek_total = (7*ad->new_seek_total + 256*(u64)sdist)/8; | |
699 | ad->new_seek_mean = ad->new_seek_total / 256; | |
700 | } | |
701 | ||
702 | /* | |
703 | * Don't allow the seek distance to get too large from the | |
704 | * odd fragment, pagein, etc | |
705 | */ | |
706 | if (aic->seek_samples <= 60) /* second&third seek */ | |
707 | sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*1024); | |
708 | else | |
709 | sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*64); | |
710 | ||
711 | aic->seek_samples = (7*aic->seek_samples + 256) / 8; | |
712 | aic->seek_total = (7*aic->seek_total + (u64)256*sdist) / 8; | |
713 | total = aic->seek_total + (aic->seek_samples/2); | |
714 | do_div(total, aic->seek_samples); | |
715 | aic->seek_mean = (sector_t)total; | |
716 | } | |
717 | ||
718 | /* | |
719 | * as_update_iohist keeps a decaying histogram of IO thinktimes, and | |
720 | * updates @aic->ttime_mean based on that. It is called when a new | |
721 | * request is queued. | |
722 | */ | |
723 | static void as_update_iohist(struct as_data *ad, struct as_io_context *aic, | |
724 | struct request *rq) | |
725 | { | |
726 | struct as_rq *arq = RQ_DATA(rq); | |
727 | int data_dir = arq->is_sync; | |
728 | unsigned long thinktime = 0; | |
729 | sector_t seek_dist; | |
730 | ||
731 | if (aic == NULL) | |
732 | return; | |
733 | ||
734 | if (data_dir == REQ_SYNC) { | |
735 | unsigned long in_flight = atomic_read(&aic->nr_queued) | |
736 | + atomic_read(&aic->nr_dispatched); | |
737 | spin_lock(&aic->lock); | |
738 | if (test_bit(AS_TASK_IORUNNING, &aic->state) || | |
739 | test_bit(AS_TASK_IOSTARTED, &aic->state)) { | |
740 | /* Calculate read -> read thinktime */ | |
741 | if (test_bit(AS_TASK_IORUNNING, &aic->state) | |
742 | && in_flight == 0) { | |
743 | thinktime = jiffies - aic->last_end_request; | |
744 | thinktime = min(thinktime, MAX_THINKTIME-1); | |
745 | } | |
746 | as_update_thinktime(ad, aic, thinktime); | |
747 | ||
748 | /* Calculate read -> read seek distance */ | |
749 | if (aic->last_request_pos < rq->sector) | |
750 | seek_dist = rq->sector - aic->last_request_pos; | |
751 | else | |
752 | seek_dist = aic->last_request_pos - rq->sector; | |
753 | as_update_seekdist(ad, aic, seek_dist); | |
754 | } | |
755 | aic->last_request_pos = rq->sector + rq->nr_sectors; | |
756 | set_bit(AS_TASK_IOSTARTED, &aic->state); | |
757 | spin_unlock(&aic->lock); | |
758 | } | |
759 | } | |
760 | ||
1da177e4 LT |
761 | /* |
762 | * as_close_req decides if one request is considered "close" to the | |
763 | * previous one issued. | |
764 | */ | |
f5b3db00 NP |
765 | static int as_close_req(struct as_data *ad, struct as_io_context *aic, |
766 | struct as_rq *arq) | |
1da177e4 LT |
767 | { |
768 | unsigned long delay; /* milliseconds */ | |
769 | sector_t last = ad->last_sector[ad->batch_data_dir]; | |
770 | sector_t next = arq->request->sector; | |
771 | sector_t delta; /* acceptable close offset (in sectors) */ | |
f5b3db00 | 772 | sector_t s; |
1da177e4 LT |
773 | |
774 | if (ad->antic_status == ANTIC_OFF || !ad->ioc_finished) | |
775 | delay = 0; | |
776 | else | |
777 | delay = ((jiffies - ad->antic_start) * 1000) / HZ; | |
778 | ||
f5b3db00 NP |
779 | if (delay == 0) |
780 | delta = 8192; | |
1da177e4 | 781 | else if (delay <= 20 && delay <= ad->antic_expire) |
f5b3db00 | 782 | delta = 8192 << delay; |
1da177e4 LT |
783 | else |
784 | return 1; | |
785 | ||
f5b3db00 NP |
786 | if ((last <= next + (delta>>1)) && (next <= last + delta)) |
787 | return 1; | |
788 | ||
789 | if (last < next) | |
790 | s = next - last; | |
791 | else | |
792 | s = last - next; | |
793 | ||
794 | if (aic->seek_samples == 0) { | |
795 | /* | |
796 | * Process has just started IO. Use past statistics to | |
797 | * gauge success possibility | |
798 | */ | |
799 | if (ad->new_seek_mean > s) { | |
800 | /* this request is better than what we're expecting */ | |
801 | return 1; | |
802 | } | |
803 | ||
804 | } else { | |
805 | if (aic->seek_mean > s) { | |
806 | /* this request is better than what we're expecting */ | |
807 | return 1; | |
808 | } | |
809 | } | |
810 | ||
811 | return 0; | |
1da177e4 LT |
812 | } |
813 | ||
814 | /* | |
815 | * as_can_break_anticipation returns true if we have been anticipating this | |
816 | * request. | |
817 | * | |
818 | * It also returns true if the process against which we are anticipating | |
819 | * submits a write - that's presumably an fsync, O_SYNC write, etc. We want to | |
820 | * dispatch it ASAP, because we know that application will not be submitting | |
821 | * any new reads. | |
822 | * | |
f5b3db00 | 823 | * If the task which has submitted the request has exited, break anticipation. |
1da177e4 LT |
824 | * |
825 | * If this task has queued some other IO, do not enter enticipation. | |
826 | */ | |
827 | static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq) | |
828 | { | |
829 | struct io_context *ioc; | |
830 | struct as_io_context *aic; | |
1da177e4 LT |
831 | |
832 | ioc = ad->io_context; | |
833 | BUG_ON(!ioc); | |
834 | ||
835 | if (arq && ioc == arq->io_context) { | |
836 | /* request from same process */ | |
837 | return 1; | |
838 | } | |
839 | ||
840 | if (ad->ioc_finished && as_antic_expired(ad)) { | |
841 | /* | |
842 | * In this situation status should really be FINISHED, | |
843 | * however the timer hasn't had the chance to run yet. | |
844 | */ | |
845 | return 1; | |
846 | } | |
847 | ||
848 | aic = ioc->aic; | |
849 | if (!aic) | |
850 | return 0; | |
851 | ||
1da177e4 LT |
852 | if (atomic_read(&aic->nr_queued) > 0) { |
853 | /* process has more requests queued */ | |
854 | return 1; | |
855 | } | |
856 | ||
857 | if (atomic_read(&aic->nr_dispatched) > 0) { | |
858 | /* process has more requests dispatched */ | |
859 | return 1; | |
860 | } | |
861 | ||
f5b3db00 | 862 | if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, aic, arq)) { |
1da177e4 LT |
863 | /* |
864 | * Found a close request that is not one of ours. | |
865 | * | |
f5b3db00 NP |
866 | * This makes close requests from another process update |
867 | * our IO history. Is generally useful when there are | |
1da177e4 LT |
868 | * two or more cooperating processes working in the same |
869 | * area. | |
870 | */ | |
f5b3db00 NP |
871 | if (!test_bit(AS_TASK_RUNNING, &aic->state)) { |
872 | if (aic->ttime_samples == 0) | |
873 | ad->exit_prob = (7*ad->exit_prob + 256)/8; | |
874 | ||
875 | ad->exit_no_coop = (7*ad->exit_no_coop)/8; | |
876 | } | |
877 | ||
878 | as_update_iohist(ad, aic, arq->request); | |
1da177e4 LT |
879 | return 1; |
880 | } | |
881 | ||
f5b3db00 NP |
882 | if (!test_bit(AS_TASK_RUNNING, &aic->state)) { |
883 | /* process anticipated on has exited */ | |
884 | if (aic->ttime_samples == 0) | |
885 | ad->exit_prob = (7*ad->exit_prob + 256)/8; | |
886 | ||
887 | if (ad->exit_no_coop > 128) | |
888 | return 1; | |
889 | } | |
1da177e4 LT |
890 | |
891 | if (aic->ttime_samples == 0) { | |
892 | if (ad->new_ttime_mean > ad->antic_expire) | |
893 | return 1; | |
f5b3db00 | 894 | if (ad->exit_prob * ad->exit_no_coop > 128*256) |
1da177e4 LT |
895 | return 1; |
896 | } else if (aic->ttime_mean > ad->antic_expire) { | |
897 | /* the process thinks too much between requests */ | |
898 | return 1; | |
899 | } | |
900 | ||
1da177e4 LT |
901 | return 0; |
902 | } | |
903 | ||
904 | /* | |
905 | * as_can_anticipate indicates weather we should either run arq | |
906 | * or keep anticipating a better request. | |
907 | */ | |
908 | static int as_can_anticipate(struct as_data *ad, struct as_rq *arq) | |
909 | { | |
910 | if (!ad->io_context) | |
911 | /* | |
912 | * Last request submitted was a write | |
913 | */ | |
914 | return 0; | |
915 | ||
916 | if (ad->antic_status == ANTIC_FINISHED) | |
917 | /* | |
918 | * Don't restart if we have just finished. Run the next request | |
919 | */ | |
920 | return 0; | |
921 | ||
922 | if (as_can_break_anticipation(ad, arq)) | |
923 | /* | |
924 | * This request is a good candidate. Don't keep anticipating, | |
925 | * run it. | |
926 | */ | |
927 | return 0; | |
928 | ||
929 | /* | |
930 | * OK from here, we haven't finished, and don't have a decent request! | |
931 | * Status is either ANTIC_OFF so start waiting, | |
932 | * ANTIC_WAIT_REQ so continue waiting for request to finish | |
933 | * or ANTIC_WAIT_NEXT so continue waiting for an acceptable request. | |
1da177e4 LT |
934 | */ |
935 | ||
936 | return 1; | |
937 | } | |
938 | ||
1da177e4 LT |
939 | /* |
940 | * as_update_arq must be called whenever a request (arq) is added to | |
941 | * the sort_list. This function keeps caches up to date, and checks if the | |
942 | * request might be one we are "anticipating" | |
943 | */ | |
944 | static void as_update_arq(struct as_data *ad, struct as_rq *arq) | |
945 | { | |
946 | const int data_dir = arq->is_sync; | |
947 | ||
948 | /* keep the next_arq cache up to date */ | |
949 | ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]); | |
950 | ||
951 | /* | |
952 | * have we been anticipating this request? | |
953 | * or does it come from the same process as the one we are anticipating | |
954 | * for? | |
955 | */ | |
956 | if (ad->antic_status == ANTIC_WAIT_REQ | |
957 | || ad->antic_status == ANTIC_WAIT_NEXT) { | |
958 | if (as_can_break_anticipation(ad, arq)) | |
959 | as_antic_stop(ad); | |
960 | } | |
961 | } | |
962 | ||
963 | /* | |
964 | * Gathers timings and resizes the write batch automatically | |
965 | */ | |
966 | static void update_write_batch(struct as_data *ad) | |
967 | { | |
968 | unsigned long batch = ad->batch_expire[REQ_ASYNC]; | |
969 | long write_time; | |
970 | ||
971 | write_time = (jiffies - ad->current_batch_expires) + batch; | |
972 | if (write_time < 0) | |
973 | write_time = 0; | |
974 | ||
975 | if (write_time > batch && !ad->write_batch_idled) { | |
976 | if (write_time > batch * 3) | |
977 | ad->write_batch_count /= 2; | |
978 | else | |
979 | ad->write_batch_count--; | |
980 | } else if (write_time < batch && ad->current_write_count == 0) { | |
981 | if (batch > write_time * 3) | |
982 | ad->write_batch_count *= 2; | |
983 | else | |
984 | ad->write_batch_count++; | |
985 | } | |
986 | ||
987 | if (ad->write_batch_count < 1) | |
988 | ad->write_batch_count = 1; | |
989 | } | |
990 | ||
991 | /* | |
992 | * as_completed_request is to be called when a request has completed and | |
993 | * returned something to the requesting process, be it an error or data. | |
994 | */ | |
995 | static void as_completed_request(request_queue_t *q, struct request *rq) | |
996 | { | |
997 | struct as_data *ad = q->elevator->elevator_data; | |
998 | struct as_rq *arq = RQ_DATA(rq); | |
999 | ||
1000 | WARN_ON(!list_empty(&rq->queuelist)); | |
1001 | ||
1da177e4 LT |
1002 | if (arq->state != AS_RQ_REMOVED) { |
1003 | printk("arq->state %d\n", arq->state); | |
1004 | WARN_ON(1); | |
1005 | goto out; | |
1006 | } | |
1007 | ||
1da177e4 LT |
1008 | if (ad->changed_batch && ad->nr_dispatched == 1) { |
1009 | kblockd_schedule_work(&ad->antic_work); | |
1010 | ad->changed_batch = 0; | |
1011 | ||
1012 | if (ad->batch_data_dir == REQ_SYNC) | |
1013 | ad->new_batch = 1; | |
1014 | } | |
1015 | WARN_ON(ad->nr_dispatched == 0); | |
1016 | ad->nr_dispatched--; | |
1017 | ||
1018 | /* | |
1019 | * Start counting the batch from when a request of that direction is | |
1020 | * actually serviced. This should help devices with big TCQ windows | |
1021 | * and writeback caches | |
1022 | */ | |
1023 | if (ad->new_batch && ad->batch_data_dir == arq->is_sync) { | |
1024 | update_write_batch(ad); | |
1025 | ad->current_batch_expires = jiffies + | |
1026 | ad->batch_expire[REQ_SYNC]; | |
1027 | ad->new_batch = 0; | |
1028 | } | |
1029 | ||
1030 | if (ad->io_context == arq->io_context && ad->io_context) { | |
1031 | ad->antic_start = jiffies; | |
1032 | ad->ioc_finished = 1; | |
1033 | if (ad->antic_status == ANTIC_WAIT_REQ) { | |
1034 | /* | |
1035 | * We were waiting on this request, now anticipate | |
1036 | * the next one | |
1037 | */ | |
1038 | as_antic_waitnext(ad); | |
1039 | } | |
1040 | } | |
1041 | ||
b4878f24 | 1042 | as_put_io_context(arq); |
1da177e4 LT |
1043 | out: |
1044 | arq->state = AS_RQ_POSTSCHED; | |
1045 | } | |
1046 | ||
1047 | /* | |
1048 | * as_remove_queued_request removes a request from the pre dispatch queue | |
1049 | * without updating refcounts. It is expected the caller will drop the | |
1050 | * reference unless it replaces the request at somepart of the elevator | |
1051 | * (ie. the dispatch queue) | |
1052 | */ | |
1053 | static void as_remove_queued_request(request_queue_t *q, struct request *rq) | |
1054 | { | |
1055 | struct as_rq *arq = RQ_DATA(rq); | |
1056 | const int data_dir = arq->is_sync; | |
1057 | struct as_data *ad = q->elevator->elevator_data; | |
1058 | ||
1059 | WARN_ON(arq->state != AS_RQ_QUEUED); | |
1060 | ||
1061 | if (arq->io_context && arq->io_context->aic) { | |
1062 | BUG_ON(!atomic_read(&arq->io_context->aic->nr_queued)); | |
1063 | atomic_dec(&arq->io_context->aic->nr_queued); | |
1064 | } | |
1065 | ||
1066 | /* | |
1067 | * Update the "next_arq" cache if we are about to remove its | |
1068 | * entry | |
1069 | */ | |
1070 | if (ad->next_arq[data_dir] == arq) | |
1071 | ad->next_arq[data_dir] = as_find_next_arq(ad, arq); | |
1072 | ||
1073 | list_del_init(&arq->fifo); | |
98b11471 | 1074 | as_del_arq_hash(arq); |
1da177e4 LT |
1075 | as_del_arq_rb(ad, arq); |
1076 | } | |
1077 | ||
1da177e4 LT |
1078 | /* |
1079 | * as_fifo_expired returns 0 if there are no expired reads on the fifo, | |
1080 | * 1 otherwise. It is ratelimited so that we only perform the check once per | |
1081 | * `fifo_expire' interval. Otherwise a large number of expired requests | |
1082 | * would create a hopeless seekstorm. | |
1083 | * | |
1084 | * See as_antic_expired comment. | |
1085 | */ | |
1086 | static int as_fifo_expired(struct as_data *ad, int adir) | |
1087 | { | |
1088 | struct as_rq *arq; | |
1089 | long delta_jif; | |
1090 | ||
1091 | delta_jif = jiffies - ad->last_check_fifo[adir]; | |
1092 | if (unlikely(delta_jif < 0)) | |
1093 | delta_jif = -delta_jif; | |
1094 | if (delta_jif < ad->fifo_expire[adir]) | |
1095 | return 0; | |
1096 | ||
1097 | ad->last_check_fifo[adir] = jiffies; | |
1098 | ||
1099 | if (list_empty(&ad->fifo_list[adir])) | |
1100 | return 0; | |
1101 | ||
1102 | arq = list_entry_fifo(ad->fifo_list[adir].next); | |
1103 | ||
1104 | return time_after(jiffies, arq->expires); | |
1105 | } | |
1106 | ||
1107 | /* | |
1108 | * as_batch_expired returns true if the current batch has expired. A batch | |
1109 | * is a set of reads or a set of writes. | |
1110 | */ | |
1111 | static inline int as_batch_expired(struct as_data *ad) | |
1112 | { | |
1113 | if (ad->changed_batch || ad->new_batch) | |
1114 | return 0; | |
1115 | ||
1116 | if (ad->batch_data_dir == REQ_SYNC) | |
1117 | /* TODO! add a check so a complete fifo gets written? */ | |
1118 | return time_after(jiffies, ad->current_batch_expires); | |
1119 | ||
1120 | return time_after(jiffies, ad->current_batch_expires) | |
1121 | || ad->current_write_count == 0; | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * move an entry to dispatch queue | |
1126 | */ | |
1127 | static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq) | |
1128 | { | |
1129 | struct request *rq = arq->request; | |
1da177e4 LT |
1130 | const int data_dir = arq->is_sync; |
1131 | ||
1132 | BUG_ON(!ON_RB(&arq->rb_node)); | |
1133 | ||
1134 | as_antic_stop(ad); | |
1135 | ad->antic_status = ANTIC_OFF; | |
1136 | ||
1137 | /* | |
1138 | * This has to be set in order to be correctly updated by | |
1139 | * as_find_next_arq | |
1140 | */ | |
1141 | ad->last_sector[data_dir] = rq->sector + rq->nr_sectors; | |
1142 | ||
1143 | if (data_dir == REQ_SYNC) { | |
1144 | /* In case we have to anticipate after this */ | |
1145 | copy_io_context(&ad->io_context, &arq->io_context); | |
1146 | } else { | |
1147 | if (ad->io_context) { | |
1148 | put_io_context(ad->io_context); | |
1149 | ad->io_context = NULL; | |
1150 | } | |
1151 | ||
1152 | if (ad->current_write_count != 0) | |
1153 | ad->current_write_count--; | |
1154 | } | |
1155 | ad->ioc_finished = 0; | |
1156 | ||
1157 | ad->next_arq[data_dir] = as_find_next_arq(ad, arq); | |
1158 | ||
1159 | /* | |
1160 | * take it off the sort and fifo list, add to dispatch queue | |
1161 | */ | |
1da177e4 LT |
1162 | as_remove_queued_request(ad->q, rq); |
1163 | WARN_ON(arq->state != AS_RQ_QUEUED); | |
1164 | ||
b4878f24 JA |
1165 | elv_dispatch_sort(ad->q, rq); |
1166 | ||
1da177e4 LT |
1167 | arq->state = AS_RQ_DISPATCHED; |
1168 | if (arq->io_context && arq->io_context->aic) | |
1169 | atomic_inc(&arq->io_context->aic->nr_dispatched); | |
1170 | ad->nr_dispatched++; | |
1171 | } | |
1172 | ||
1173 | /* | |
1174 | * as_dispatch_request selects the best request according to | |
1175 | * read/write expire, batch expire, etc, and moves it to the dispatch | |
1176 | * queue. Returns 1 if a request was found, 0 otherwise. | |
1177 | */ | |
b4878f24 | 1178 | static int as_dispatch_request(request_queue_t *q, int force) |
1da177e4 | 1179 | { |
b4878f24 | 1180 | struct as_data *ad = q->elevator->elevator_data; |
1da177e4 LT |
1181 | struct as_rq *arq; |
1182 | const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]); | |
1183 | const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]); | |
1184 | ||
b4878f24 JA |
1185 | if (unlikely(force)) { |
1186 | /* | |
1187 | * Forced dispatch, accounting is useless. Reset | |
1188 | * accounting states and dump fifo_lists. Note that | |
1189 | * batch_data_dir is reset to REQ_SYNC to avoid | |
1190 | * screwing write batch accounting as write batch | |
1191 | * accounting occurs on W->R transition. | |
1192 | */ | |
1193 | int dispatched = 0; | |
1194 | ||
1195 | ad->batch_data_dir = REQ_SYNC; | |
1196 | ad->changed_batch = 0; | |
1197 | ad->new_batch = 0; | |
1198 | ||
1199 | while (ad->next_arq[REQ_SYNC]) { | |
1200 | as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]); | |
1201 | dispatched++; | |
1202 | } | |
1203 | ad->last_check_fifo[REQ_SYNC] = jiffies; | |
1204 | ||
1205 | while (ad->next_arq[REQ_ASYNC]) { | |
1206 | as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]); | |
1207 | dispatched++; | |
1208 | } | |
1209 | ad->last_check_fifo[REQ_ASYNC] = jiffies; | |
1210 | ||
1211 | return dispatched; | |
1212 | } | |
1213 | ||
1da177e4 LT |
1214 | /* Signal that the write batch was uncontended, so we can't time it */ |
1215 | if (ad->batch_data_dir == REQ_ASYNC && !reads) { | |
1216 | if (ad->current_write_count == 0 || !writes) | |
1217 | ad->write_batch_idled = 1; | |
1218 | } | |
1219 | ||
1220 | if (!(reads || writes) | |
1221 | || ad->antic_status == ANTIC_WAIT_REQ | |
1222 | || ad->antic_status == ANTIC_WAIT_NEXT | |
1223 | || ad->changed_batch) | |
1224 | return 0; | |
1225 | ||
f5b3db00 | 1226 | if (!(reads && writes && as_batch_expired(ad))) { |
1da177e4 LT |
1227 | /* |
1228 | * batch is still running or no reads or no writes | |
1229 | */ | |
1230 | arq = ad->next_arq[ad->batch_data_dir]; | |
1231 | ||
1232 | if (ad->batch_data_dir == REQ_SYNC && ad->antic_expire) { | |
1233 | if (as_fifo_expired(ad, REQ_SYNC)) | |
1234 | goto fifo_expired; | |
1235 | ||
1236 | if (as_can_anticipate(ad, arq)) { | |
1237 | as_antic_waitreq(ad); | |
1238 | return 0; | |
1239 | } | |
1240 | } | |
1241 | ||
1242 | if (arq) { | |
1243 | /* we have a "next request" */ | |
1244 | if (reads && !writes) | |
1245 | ad->current_batch_expires = | |
1246 | jiffies + ad->batch_expire[REQ_SYNC]; | |
1247 | goto dispatch_request; | |
1248 | } | |
1249 | } | |
1250 | ||
1251 | /* | |
1252 | * at this point we are not running a batch. select the appropriate | |
1253 | * data direction (read / write) | |
1254 | */ | |
1255 | ||
1256 | if (reads) { | |
1257 | BUG_ON(RB_EMPTY(&ad->sort_list[REQ_SYNC])); | |
1258 | ||
1259 | if (writes && ad->batch_data_dir == REQ_SYNC) | |
1260 | /* | |
1261 | * Last batch was a read, switch to writes | |
1262 | */ | |
1263 | goto dispatch_writes; | |
1264 | ||
1265 | if (ad->batch_data_dir == REQ_ASYNC) { | |
1266 | WARN_ON(ad->new_batch); | |
1267 | ad->changed_batch = 1; | |
1268 | } | |
1269 | ad->batch_data_dir = REQ_SYNC; | |
1270 | arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); | |
1271 | ad->last_check_fifo[ad->batch_data_dir] = jiffies; | |
1272 | goto dispatch_request; | |
1273 | } | |
1274 | ||
1275 | /* | |
1276 | * the last batch was a read | |
1277 | */ | |
1278 | ||
1279 | if (writes) { | |
1280 | dispatch_writes: | |
1281 | BUG_ON(RB_EMPTY(&ad->sort_list[REQ_ASYNC])); | |
1282 | ||
1283 | if (ad->batch_data_dir == REQ_SYNC) { | |
1284 | ad->changed_batch = 1; | |
1285 | ||
1286 | /* | |
1287 | * new_batch might be 1 when the queue runs out of | |
1288 | * reads. A subsequent submission of a write might | |
1289 | * cause a change of batch before the read is finished. | |
1290 | */ | |
1291 | ad->new_batch = 0; | |
1292 | } | |
1293 | ad->batch_data_dir = REQ_ASYNC; | |
1294 | ad->current_write_count = ad->write_batch_count; | |
1295 | ad->write_batch_idled = 0; | |
1296 | arq = ad->next_arq[ad->batch_data_dir]; | |
1297 | goto dispatch_request; | |
1298 | } | |
1299 | ||
1300 | BUG(); | |
1301 | return 0; | |
1302 | ||
1303 | dispatch_request: | |
1304 | /* | |
1305 | * If a request has expired, service it. | |
1306 | */ | |
1307 | ||
1308 | if (as_fifo_expired(ad, ad->batch_data_dir)) { | |
1309 | fifo_expired: | |
1310 | arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next); | |
1311 | BUG_ON(arq == NULL); | |
1312 | } | |
1313 | ||
1314 | if (ad->changed_batch) { | |
1315 | WARN_ON(ad->new_batch); | |
1316 | ||
1317 | if (ad->nr_dispatched) | |
1318 | return 0; | |
1319 | ||
1320 | if (ad->batch_data_dir == REQ_ASYNC) | |
1321 | ad->current_batch_expires = jiffies + | |
1322 | ad->batch_expire[REQ_ASYNC]; | |
1323 | else | |
1324 | ad->new_batch = 1; | |
1325 | ||
1326 | ad->changed_batch = 0; | |
1327 | } | |
1328 | ||
1329 | /* | |
1330 | * arq is the selected appropriate request. | |
1331 | */ | |
1332 | as_move_to_dispatch(ad, arq); | |
1333 | ||
1334 | return 1; | |
1335 | } | |
1336 | ||
1da177e4 LT |
1337 | /* |
1338 | * add arq to rbtree and fifo | |
1339 | */ | |
b4878f24 | 1340 | static void as_add_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1341 | { |
b4878f24 JA |
1342 | struct as_data *ad = q->elevator->elevator_data; |
1343 | struct as_rq *arq = RQ_DATA(rq); | |
1da177e4 LT |
1344 | int data_dir; |
1345 | ||
b4878f24 JA |
1346 | arq->state = AS_RQ_NEW; |
1347 | ||
1da177e4 LT |
1348 | if (rq_data_dir(arq->request) == READ |
1349 | || current->flags&PF_SYNCWRITE) | |
1350 | arq->is_sync = 1; | |
1351 | else | |
1352 | arq->is_sync = 0; | |
1353 | data_dir = arq->is_sync; | |
1354 | ||
1355 | arq->io_context = as_get_io_context(); | |
1356 | ||
1357 | if (arq->io_context) { | |
1358 | as_update_iohist(ad, arq->io_context->aic, arq->request); | |
1359 | atomic_inc(&arq->io_context->aic->nr_queued); | |
1360 | } | |
1361 | ||
ef9be1d3 TH |
1362 | as_add_arq_rb(ad, arq); |
1363 | if (rq_mergeable(arq->request)) | |
1364 | as_add_arq_hash(ad, arq); | |
1da177e4 | 1365 | |
ef9be1d3 TH |
1366 | /* |
1367 | * set expire time (only used for reads) and add to fifo list | |
1368 | */ | |
1369 | arq->expires = jiffies + ad->fifo_expire[data_dir]; | |
1370 | list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]); | |
1da177e4 | 1371 | |
ef9be1d3 | 1372 | as_update_arq(ad, arq); /* keep state machine up to date */ |
1da177e4 LT |
1373 | arq->state = AS_RQ_QUEUED; |
1374 | } | |
1375 | ||
b4878f24 | 1376 | static void as_activate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1377 | { |
1da177e4 LT |
1378 | struct as_rq *arq = RQ_DATA(rq); |
1379 | ||
b4878f24 JA |
1380 | WARN_ON(arq->state != AS_RQ_DISPATCHED); |
1381 | arq->state = AS_RQ_REMOVED; | |
1382 | if (arq->io_context && arq->io_context->aic) | |
1383 | atomic_dec(&arq->io_context->aic->nr_dispatched); | |
1da177e4 LT |
1384 | } |
1385 | ||
b4878f24 | 1386 | static void as_deactivate_request(request_queue_t *q, struct request *rq) |
1da177e4 | 1387 | { |
1da177e4 LT |
1388 | struct as_rq *arq = RQ_DATA(rq); |
1389 | ||
b4878f24 JA |
1390 | WARN_ON(arq->state != AS_RQ_REMOVED); |
1391 | arq->state = AS_RQ_DISPATCHED; | |
1392 | if (arq->io_context && arq->io_context->aic) | |
1393 | atomic_inc(&arq->io_context->aic->nr_dispatched); | |
1da177e4 LT |
1394 | } |
1395 | ||
1396 | /* | |
1397 | * as_queue_empty tells us if there are requests left in the device. It may | |
1398 | * not be the case that a driver can get the next request even if the queue | |
1399 | * is not empty - it is used in the block layer to check for plugging and | |
1400 | * merging opportunities | |
1401 | */ | |
1402 | static int as_queue_empty(request_queue_t *q) | |
1403 | { | |
1404 | struct as_data *ad = q->elevator->elevator_data; | |
1405 | ||
b4878f24 JA |
1406 | return list_empty(&ad->fifo_list[REQ_ASYNC]) |
1407 | && list_empty(&ad->fifo_list[REQ_SYNC]); | |
1da177e4 LT |
1408 | } |
1409 | ||
f5b3db00 NP |
1410 | static struct request *as_former_request(request_queue_t *q, |
1411 | struct request *rq) | |
1da177e4 LT |
1412 | { |
1413 | struct as_rq *arq = RQ_DATA(rq); | |
1414 | struct rb_node *rbprev = rb_prev(&arq->rb_node); | |
1415 | struct request *ret = NULL; | |
1416 | ||
1417 | if (rbprev) | |
1418 | ret = rb_entry_arq(rbprev)->request; | |
1419 | ||
1420 | return ret; | |
1421 | } | |
1422 | ||
f5b3db00 NP |
1423 | static struct request *as_latter_request(request_queue_t *q, |
1424 | struct request *rq) | |
1da177e4 LT |
1425 | { |
1426 | struct as_rq *arq = RQ_DATA(rq); | |
1427 | struct rb_node *rbnext = rb_next(&arq->rb_node); | |
1428 | struct request *ret = NULL; | |
1429 | ||
1430 | if (rbnext) | |
1431 | ret = rb_entry_arq(rbnext)->request; | |
1432 | ||
1433 | return ret; | |
1434 | } | |
1435 | ||
1436 | static int | |
1437 | as_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
1438 | { | |
1439 | struct as_data *ad = q->elevator->elevator_data; | |
1440 | sector_t rb_key = bio->bi_sector + bio_sectors(bio); | |
1441 | struct request *__rq; | |
1442 | int ret; | |
1443 | ||
1da177e4 LT |
1444 | /* |
1445 | * see if the merge hash can satisfy a back merge | |
1446 | */ | |
1447 | __rq = as_find_arq_hash(ad, bio->bi_sector); | |
1448 | if (__rq) { | |
1449 | BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); | |
1450 | ||
1451 | if (elv_rq_merge_ok(__rq, bio)) { | |
1452 | ret = ELEVATOR_BACK_MERGE; | |
1453 | goto out; | |
1454 | } | |
1455 | } | |
1456 | ||
1457 | /* | |
1458 | * check for front merge | |
1459 | */ | |
1460 | __rq = as_find_arq_rb(ad, rb_key, bio_data_dir(bio)); | |
1461 | if (__rq) { | |
1462 | BUG_ON(rb_key != rq_rb_key(__rq)); | |
1463 | ||
1464 | if (elv_rq_merge_ok(__rq, bio)) { | |
1465 | ret = ELEVATOR_FRONT_MERGE; | |
1466 | goto out; | |
1467 | } | |
1468 | } | |
1469 | ||
1470 | return ELEVATOR_NO_MERGE; | |
1471 | out: | |
1da177e4 LT |
1472 | if (ret) { |
1473 | if (rq_mergeable(__rq)) | |
1474 | as_hot_arq_hash(ad, RQ_DATA(__rq)); | |
1475 | } | |
1476 | *req = __rq; | |
1477 | return ret; | |
1478 | } | |
1479 | ||
1480 | static void as_merged_request(request_queue_t *q, struct request *req) | |
1481 | { | |
1482 | struct as_data *ad = q->elevator->elevator_data; | |
1483 | struct as_rq *arq = RQ_DATA(req); | |
1484 | ||
1485 | /* | |
1486 | * hash always needs to be repositioned, key is end sector | |
1487 | */ | |
1488 | as_del_arq_hash(arq); | |
1489 | as_add_arq_hash(ad, arq); | |
1490 | ||
1491 | /* | |
1492 | * if the merge was a front merge, we need to reposition request | |
1493 | */ | |
1494 | if (rq_rb_key(req) != arq->rb_key) { | |
1da177e4 | 1495 | as_del_arq_rb(ad, arq); |
ef9be1d3 | 1496 | as_add_arq_rb(ad, arq); |
1da177e4 LT |
1497 | /* |
1498 | * Note! At this stage of this and the next function, our next | |
1499 | * request may not be optimal - eg the request may have "grown" | |
1500 | * behind the disk head. We currently don't bother adjusting. | |
1501 | */ | |
1502 | } | |
1da177e4 LT |
1503 | } |
1504 | ||
f5b3db00 NP |
1505 | static void as_merged_requests(request_queue_t *q, struct request *req, |
1506 | struct request *next) | |
1da177e4 LT |
1507 | { |
1508 | struct as_data *ad = q->elevator->elevator_data; | |
1509 | struct as_rq *arq = RQ_DATA(req); | |
1510 | struct as_rq *anext = RQ_DATA(next); | |
1511 | ||
1512 | BUG_ON(!arq); | |
1513 | BUG_ON(!anext); | |
1514 | ||
1515 | /* | |
1516 | * reposition arq (this is the merged request) in hash, and in rbtree | |
1517 | * in case of a front merge | |
1518 | */ | |
1519 | as_del_arq_hash(arq); | |
1520 | as_add_arq_hash(ad, arq); | |
1521 | ||
1522 | if (rq_rb_key(req) != arq->rb_key) { | |
1da177e4 | 1523 | as_del_arq_rb(ad, arq); |
ef9be1d3 | 1524 | as_add_arq_rb(ad, arq); |
1da177e4 LT |
1525 | } |
1526 | ||
1527 | /* | |
1528 | * if anext expires before arq, assign its expire time to arq | |
1529 | * and move into anext position (anext will be deleted) in fifo | |
1530 | */ | |
1531 | if (!list_empty(&arq->fifo) && !list_empty(&anext->fifo)) { | |
1532 | if (time_before(anext->expires, arq->expires)) { | |
1533 | list_move(&arq->fifo, &anext->fifo); | |
1534 | arq->expires = anext->expires; | |
1535 | /* | |
1536 | * Don't copy here but swap, because when anext is | |
1537 | * removed below, it must contain the unused context | |
1538 | */ | |
1539 | swap_io_context(&arq->io_context, &anext->io_context); | |
1540 | } | |
1541 | } | |
1542 | ||
1da177e4 LT |
1543 | /* |
1544 | * kill knowledge of next, this one is a goner | |
1545 | */ | |
1546 | as_remove_queued_request(q, next); | |
b4878f24 | 1547 | as_put_io_context(anext); |
1da177e4 LT |
1548 | |
1549 | anext->state = AS_RQ_MERGED; | |
1550 | } | |
1551 | ||
1552 | /* | |
1553 | * This is executed in a "deferred" process context, by kblockd. It calls the | |
1554 | * driver's request_fn so the driver can submit that request. | |
1555 | * | |
1556 | * IMPORTANT! This guy will reenter the elevator, so set up all queue global | |
1557 | * state before calling, and don't rely on any state over calls. | |
1558 | * | |
1559 | * FIXME! dispatch queue is not a queue at all! | |
1560 | */ | |
1561 | static void as_work_handler(void *data) | |
1562 | { | |
1563 | struct request_queue *q = data; | |
1564 | unsigned long flags; | |
1565 | ||
1566 | spin_lock_irqsave(q->queue_lock, flags); | |
b4878f24 | 1567 | if (!as_queue_empty(q)) |
1da177e4 LT |
1568 | q->request_fn(q); |
1569 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1570 | } | |
1571 | ||
1572 | static void as_put_request(request_queue_t *q, struct request *rq) | |
1573 | { | |
1574 | struct as_data *ad = q->elevator->elevator_data; | |
1575 | struct as_rq *arq = RQ_DATA(rq); | |
1576 | ||
1577 | if (!arq) { | |
1578 | WARN_ON(1); | |
1579 | return; | |
1580 | } | |
1581 | ||
b4878f24 JA |
1582 | if (unlikely(arq->state != AS_RQ_POSTSCHED && |
1583 | arq->state != AS_RQ_PRESCHED && | |
1584 | arq->state != AS_RQ_MERGED)) { | |
1da177e4 LT |
1585 | printk("arq->state %d\n", arq->state); |
1586 | WARN_ON(1); | |
1587 | } | |
1588 | ||
1589 | mempool_free(arq, ad->arq_pool); | |
1590 | rq->elevator_private = NULL; | |
1591 | } | |
1592 | ||
22e2c507 | 1593 | static int as_set_request(request_queue_t *q, struct request *rq, |
8267e268 | 1594 | struct bio *bio, gfp_t gfp_mask) |
1da177e4 LT |
1595 | { |
1596 | struct as_data *ad = q->elevator->elevator_data; | |
1597 | struct as_rq *arq = mempool_alloc(ad->arq_pool, gfp_mask); | |
1598 | ||
1599 | if (arq) { | |
1600 | memset(arq, 0, sizeof(*arq)); | |
1601 | RB_CLEAR(&arq->rb_node); | |
1602 | arq->request = rq; | |
1603 | arq->state = AS_RQ_PRESCHED; | |
1604 | arq->io_context = NULL; | |
1605 | INIT_LIST_HEAD(&arq->hash); | |
1606 | arq->on_hash = 0; | |
1607 | INIT_LIST_HEAD(&arq->fifo); | |
1608 | rq->elevator_private = arq; | |
1609 | return 0; | |
1610 | } | |
1611 | ||
1612 | return 1; | |
1613 | } | |
1614 | ||
22e2c507 | 1615 | static int as_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
1616 | { |
1617 | int ret = ELV_MQUEUE_MAY; | |
1618 | struct as_data *ad = q->elevator->elevator_data; | |
1619 | struct io_context *ioc; | |
1620 | if (ad->antic_status == ANTIC_WAIT_REQ || | |
1621 | ad->antic_status == ANTIC_WAIT_NEXT) { | |
1622 | ioc = as_get_io_context(); | |
1623 | if (ad->io_context == ioc) | |
1624 | ret = ELV_MQUEUE_MUST; | |
1625 | put_io_context(ioc); | |
1626 | } | |
1627 | ||
1628 | return ret; | |
1629 | } | |
1630 | ||
1631 | static void as_exit_queue(elevator_t *e) | |
1632 | { | |
1633 | struct as_data *ad = e->elevator_data; | |
1634 | ||
1635 | del_timer_sync(&ad->antic_timer); | |
1636 | kblockd_flush(); | |
1637 | ||
1638 | BUG_ON(!list_empty(&ad->fifo_list[REQ_SYNC])); | |
1639 | BUG_ON(!list_empty(&ad->fifo_list[REQ_ASYNC])); | |
1640 | ||
1641 | mempool_destroy(ad->arq_pool); | |
1642 | put_io_context(ad->io_context); | |
1643 | kfree(ad->hash); | |
1644 | kfree(ad); | |
1645 | } | |
1646 | ||
1647 | /* | |
1648 | * initialize elevator private data (as_data), and alloc a arq for | |
1649 | * each request on the free lists | |
1650 | */ | |
1651 | static int as_init_queue(request_queue_t *q, elevator_t *e) | |
1652 | { | |
1653 | struct as_data *ad; | |
1654 | int i; | |
1655 | ||
1656 | if (!arq_pool) | |
1657 | return -ENOMEM; | |
1658 | ||
1946089a | 1659 | ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node); |
1da177e4 LT |
1660 | if (!ad) |
1661 | return -ENOMEM; | |
1662 | memset(ad, 0, sizeof(*ad)); | |
1663 | ||
1664 | ad->q = q; /* Identify what queue the data belongs to */ | |
1665 | ||
1946089a CL |
1666 | ad->hash = kmalloc_node(sizeof(struct list_head)*AS_HASH_ENTRIES, |
1667 | GFP_KERNEL, q->node); | |
1da177e4 LT |
1668 | if (!ad->hash) { |
1669 | kfree(ad); | |
1670 | return -ENOMEM; | |
1671 | } | |
1672 | ||
1946089a CL |
1673 | ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
1674 | mempool_free_slab, arq_pool, q->node); | |
1da177e4 LT |
1675 | if (!ad->arq_pool) { |
1676 | kfree(ad->hash); | |
1677 | kfree(ad); | |
1678 | return -ENOMEM; | |
1679 | } | |
1680 | ||
1681 | /* anticipatory scheduling helpers */ | |
1682 | ad->antic_timer.function = as_antic_timeout; | |
1683 | ad->antic_timer.data = (unsigned long)q; | |
1684 | init_timer(&ad->antic_timer); | |
1685 | INIT_WORK(&ad->antic_work, as_work_handler, q); | |
1686 | ||
1687 | for (i = 0; i < AS_HASH_ENTRIES; i++) | |
1688 | INIT_LIST_HEAD(&ad->hash[i]); | |
1689 | ||
1690 | INIT_LIST_HEAD(&ad->fifo_list[REQ_SYNC]); | |
1691 | INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]); | |
1692 | ad->sort_list[REQ_SYNC] = RB_ROOT; | |
1693 | ad->sort_list[REQ_ASYNC] = RB_ROOT; | |
1da177e4 LT |
1694 | ad->fifo_expire[REQ_SYNC] = default_read_expire; |
1695 | ad->fifo_expire[REQ_ASYNC] = default_write_expire; | |
1696 | ad->antic_expire = default_antic_expire; | |
1697 | ad->batch_expire[REQ_SYNC] = default_read_batch_expire; | |
1698 | ad->batch_expire[REQ_ASYNC] = default_write_batch_expire; | |
1699 | e->elevator_data = ad; | |
1700 | ||
1701 | ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC]; | |
1702 | ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10; | |
1703 | if (ad->write_batch_count < 2) | |
1704 | ad->write_batch_count = 2; | |
1705 | ||
1706 | return 0; | |
1707 | } | |
1708 | ||
1709 | /* | |
1710 | * sysfs parts below | |
1711 | */ | |
1da177e4 LT |
1712 | |
1713 | static ssize_t | |
1714 | as_var_show(unsigned int var, char *page) | |
1715 | { | |
1da177e4 LT |
1716 | return sprintf(page, "%d\n", var); |
1717 | } | |
1718 | ||
1719 | static ssize_t | |
1720 | as_var_store(unsigned long *var, const char *page, size_t count) | |
1721 | { | |
1da177e4 LT |
1722 | char *p = (char *) page; |
1723 | ||
c9b3ad67 | 1724 | *var = simple_strtoul(p, &p, 10); |
1da177e4 LT |
1725 | return count; |
1726 | } | |
1727 | ||
e572ec7e | 1728 | static ssize_t est_time_show(elevator_t *e, char *page) |
1da177e4 | 1729 | { |
3d1ab40f | 1730 | struct as_data *ad = e->elevator_data; |
1da177e4 LT |
1731 | int pos = 0; |
1732 | ||
f5b3db00 NP |
1733 | pos += sprintf(page+pos, "%lu %% exit probability\n", |
1734 | 100*ad->exit_prob/256); | |
1735 | pos += sprintf(page+pos, "%lu %% probability of exiting without a " | |
1736 | "cooperating process submitting IO\n", | |
1737 | 100*ad->exit_no_coop/256); | |
1da177e4 | 1738 | pos += sprintf(page+pos, "%lu ms new thinktime\n", ad->new_ttime_mean); |
f5b3db00 NP |
1739 | pos += sprintf(page+pos, "%llu sectors new seek distance\n", |
1740 | (unsigned long long)ad->new_seek_mean); | |
1da177e4 LT |
1741 | |
1742 | return pos; | |
1743 | } | |
1744 | ||
1745 | #define SHOW_FUNCTION(__FUNC, __VAR) \ | |
3d1ab40f | 1746 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 1747 | { \ |
3d1ab40f | 1748 | struct as_data *ad = e->elevator_data; \ |
1da177e4 LT |
1749 | return as_var_show(jiffies_to_msecs((__VAR)), (page)); \ |
1750 | } | |
e572ec7e AV |
1751 | SHOW_FUNCTION(as_read_expire_show, ad->fifo_expire[REQ_SYNC]); |
1752 | SHOW_FUNCTION(as_write_expire_show, ad->fifo_expire[REQ_ASYNC]); | |
1753 | SHOW_FUNCTION(as_antic_expire_show, ad->antic_expire); | |
1754 | SHOW_FUNCTION(as_read_batch_expire_show, ad->batch_expire[REQ_SYNC]); | |
1755 | SHOW_FUNCTION(as_write_batch_expire_show, ad->batch_expire[REQ_ASYNC]); | |
1da177e4 LT |
1756 | #undef SHOW_FUNCTION |
1757 | ||
1758 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ | |
3d1ab40f | 1759 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 1760 | { \ |
3d1ab40f AV |
1761 | struct as_data *ad = e->elevator_data; \ |
1762 | int ret = as_var_store(__PTR, (page), count); \ | |
1da177e4 LT |
1763 | if (*(__PTR) < (MIN)) \ |
1764 | *(__PTR) = (MIN); \ | |
1765 | else if (*(__PTR) > (MAX)) \ | |
1766 | *(__PTR) = (MAX); \ | |
1767 | *(__PTR) = msecs_to_jiffies(*(__PTR)); \ | |
1768 | return ret; \ | |
1769 | } | |
e572ec7e AV |
1770 | STORE_FUNCTION(as_read_expire_store, &ad->fifo_expire[REQ_SYNC], 0, INT_MAX); |
1771 | STORE_FUNCTION(as_write_expire_store, &ad->fifo_expire[REQ_ASYNC], 0, INT_MAX); | |
1772 | STORE_FUNCTION(as_antic_expire_store, &ad->antic_expire, 0, INT_MAX); | |
1773 | STORE_FUNCTION(as_read_batch_expire_store, | |
1da177e4 | 1774 | &ad->batch_expire[REQ_SYNC], 0, INT_MAX); |
e572ec7e | 1775 | STORE_FUNCTION(as_write_batch_expire_store, |
1da177e4 LT |
1776 | &ad->batch_expire[REQ_ASYNC], 0, INT_MAX); |
1777 | #undef STORE_FUNCTION | |
1778 | ||
e572ec7e AV |
1779 | #define AS_ATTR(name) \ |
1780 | __ATTR(name, S_IRUGO|S_IWUSR, as_##name##_show, as_##name##_store) | |
1781 | ||
1782 | static struct elv_fs_entry as_attrs[] = { | |
1783 | __ATTR_RO(est_time), | |
1784 | AS_ATTR(read_expire), | |
1785 | AS_ATTR(write_expire), | |
1786 | AS_ATTR(antic_expire), | |
1787 | AS_ATTR(read_batch_expire), | |
1788 | AS_ATTR(write_batch_expire), | |
1789 | __ATTR_NULL | |
1da177e4 LT |
1790 | }; |
1791 | ||
1da177e4 LT |
1792 | static struct elevator_type iosched_as = { |
1793 | .ops = { | |
1794 | .elevator_merge_fn = as_merge, | |
1795 | .elevator_merged_fn = as_merged_request, | |
1796 | .elevator_merge_req_fn = as_merged_requests, | |
b4878f24 JA |
1797 | .elevator_dispatch_fn = as_dispatch_request, |
1798 | .elevator_add_req_fn = as_add_request, | |
1799 | .elevator_activate_req_fn = as_activate_request, | |
1da177e4 LT |
1800 | .elevator_deactivate_req_fn = as_deactivate_request, |
1801 | .elevator_queue_empty_fn = as_queue_empty, | |
1802 | .elevator_completed_req_fn = as_completed_request, | |
1803 | .elevator_former_req_fn = as_former_request, | |
1804 | .elevator_latter_req_fn = as_latter_request, | |
1805 | .elevator_set_req_fn = as_set_request, | |
1806 | .elevator_put_req_fn = as_put_request, | |
1807 | .elevator_may_queue_fn = as_may_queue, | |
1808 | .elevator_init_fn = as_init_queue, | |
1809 | .elevator_exit_fn = as_exit_queue, | |
e17a9489 | 1810 | .trim = as_trim, |
1da177e4 LT |
1811 | }, |
1812 | ||
3d1ab40f | 1813 | .elevator_attrs = as_attrs, |
1da177e4 LT |
1814 | .elevator_name = "anticipatory", |
1815 | .elevator_owner = THIS_MODULE, | |
1816 | }; | |
1817 | ||
1818 | static int __init as_init(void) | |
1819 | { | |
1820 | int ret; | |
1821 | ||
1822 | arq_pool = kmem_cache_create("as_arq", sizeof(struct as_rq), | |
1823 | 0, 0, NULL, NULL); | |
1824 | if (!arq_pool) | |
1825 | return -ENOMEM; | |
1826 | ||
1827 | ret = elv_register(&iosched_as); | |
1828 | if (!ret) { | |
1829 | /* | |
1830 | * don't allow AS to get unregistered, since we would have | |
1831 | * to browse all tasks in the system and release their | |
1832 | * as_io_context first | |
1833 | */ | |
1834 | __module_get(THIS_MODULE); | |
1835 | return 0; | |
1836 | } | |
1837 | ||
1838 | kmem_cache_destroy(arq_pool); | |
1839 | return ret; | |
1840 | } | |
1841 | ||
1842 | static void __exit as_exit(void) | |
1843 | { | |
334e94de | 1844 | DECLARE_COMPLETION(all_gone); |
1da177e4 | 1845 | elv_unregister(&iosched_as); |
334e94de | 1846 | ioc_gone = &all_gone; |
fba82272 OH |
1847 | /* ioc_gone's update must be visible before reading ioc_count */ |
1848 | smp_wmb(); | |
334e94de | 1849 | if (atomic_read(&ioc_count)) |
fba82272 | 1850 | wait_for_completion(ioc_gone); |
334e94de | 1851 | synchronize_rcu(); |
83521d3e | 1852 | kmem_cache_destroy(arq_pool); |
1da177e4 LT |
1853 | } |
1854 | ||
1855 | module_init(as_init); | |
1856 | module_exit(as_exit); | |
1857 | ||
1858 | MODULE_AUTHOR("Nick Piggin"); | |
1859 | MODULE_LICENSE("GPL"); | |
1860 | MODULE_DESCRIPTION("anticipatory IO scheduler"); |