Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/drivers/block/deadline-iosched.c | |
3 | * | |
4 | * Deadline i/o scheduler. | |
5 | * | |
6 | * Copyright (C) 2002 Jens Axboe <axboe@suse.de> | |
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 | ||
21 | /* | |
22 | * See Documentation/block/deadline-iosched.txt | |
23 | */ | |
24 | static int read_expire = HZ / 2; /* max time before a read is submitted. */ | |
25 | static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ | |
26 | static int writes_starved = 2; /* max times reads can starve a write */ | |
27 | static int fifo_batch = 16; /* # of sequential requests treated as one | |
28 | by the above parameters. For throughput. */ | |
29 | ||
30 | static const int deadline_hash_shift = 5; | |
31 | #define DL_HASH_BLOCK(sec) ((sec) >> 3) | |
32 | #define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift)) | |
33 | #define DL_HASH_ENTRIES (1 << deadline_hash_shift) | |
34 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
35 | #define list_entry_hash(ptr) list_entry((ptr), struct deadline_rq, hash) | |
36 | #define ON_HASH(drq) (drq)->on_hash | |
37 | ||
38 | struct deadline_data { | |
39 | /* | |
40 | * run time data | |
41 | */ | |
42 | ||
43 | /* | |
44 | * requests (deadline_rq s) are present on both sort_list and fifo_list | |
45 | */ | |
46 | struct rb_root sort_list[2]; | |
47 | struct list_head fifo_list[2]; | |
48 | ||
49 | /* | |
50 | * next in sort order. read, write or both are NULL | |
51 | */ | |
52 | struct deadline_rq *next_drq[2]; | |
1da177e4 LT |
53 | struct list_head *hash; /* request hash */ |
54 | unsigned int batching; /* number of sequential requests made */ | |
55 | sector_t last_sector; /* head position */ | |
56 | unsigned int starved; /* times reads have starved writes */ | |
57 | ||
58 | /* | |
59 | * settings that change how the i/o scheduler behaves | |
60 | */ | |
61 | int fifo_expire[2]; | |
62 | int fifo_batch; | |
63 | int writes_starved; | |
64 | int front_merges; | |
65 | ||
66 | mempool_t *drq_pool; | |
67 | }; | |
68 | ||
69 | /* | |
70 | * pre-request data. | |
71 | */ | |
72 | struct deadline_rq { | |
73 | /* | |
74 | * rbtree index, key is the starting offset | |
75 | */ | |
76 | struct rb_node rb_node; | |
77 | sector_t rb_key; | |
78 | ||
79 | struct request *request; | |
80 | ||
81 | /* | |
82 | * request hash, key is the ending offset (for back merge lookup) | |
83 | */ | |
84 | struct list_head hash; | |
85 | char on_hash; | |
86 | ||
87 | /* | |
88 | * expire fifo | |
89 | */ | |
90 | struct list_head fifo; | |
91 | unsigned long expires; | |
92 | }; | |
93 | ||
94 | static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq); | |
95 | ||
96 | static kmem_cache_t *drq_pool; | |
97 | ||
98 | #define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private) | |
99 | ||
100 | /* | |
101 | * the back merge hash support functions | |
102 | */ | |
103 | static inline void __deadline_del_drq_hash(struct deadline_rq *drq) | |
104 | { | |
105 | drq->on_hash = 0; | |
106 | list_del_init(&drq->hash); | |
107 | } | |
108 | ||
109 | static inline void deadline_del_drq_hash(struct deadline_rq *drq) | |
110 | { | |
111 | if (ON_HASH(drq)) | |
112 | __deadline_del_drq_hash(drq); | |
113 | } | |
114 | ||
115 | static void | |
116 | deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq) | |
117 | { | |
118 | deadline_del_drq_hash(drq); | |
119 | ||
120 | if (q->last_merge == drq->request) | |
121 | q->last_merge = NULL; | |
122 | } | |
123 | ||
124 | static inline void | |
125 | deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
126 | { | |
127 | struct request *rq = drq->request; | |
128 | ||
129 | BUG_ON(ON_HASH(drq)); | |
130 | ||
131 | drq->on_hash = 1; | |
132 | list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]); | |
133 | } | |
134 | ||
135 | /* | |
136 | * move hot entry to front of chain | |
137 | */ | |
138 | static inline void | |
139 | deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
140 | { | |
141 | struct request *rq = drq->request; | |
142 | struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))]; | |
143 | ||
144 | if (ON_HASH(drq) && drq->hash.prev != head) { | |
145 | list_del(&drq->hash); | |
146 | list_add(&drq->hash, head); | |
147 | } | |
148 | } | |
149 | ||
150 | static struct request * | |
151 | deadline_find_drq_hash(struct deadline_data *dd, sector_t offset) | |
152 | { | |
153 | struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)]; | |
154 | struct list_head *entry, *next = hash_list->next; | |
155 | ||
156 | while ((entry = next) != hash_list) { | |
157 | struct deadline_rq *drq = list_entry_hash(entry); | |
158 | struct request *__rq = drq->request; | |
159 | ||
160 | next = entry->next; | |
161 | ||
162 | BUG_ON(!ON_HASH(drq)); | |
163 | ||
164 | if (!rq_mergeable(__rq)) { | |
165 | __deadline_del_drq_hash(drq); | |
166 | continue; | |
167 | } | |
168 | ||
169 | if (rq_hash_key(__rq) == offset) | |
170 | return __rq; | |
171 | } | |
172 | ||
173 | return NULL; | |
174 | } | |
175 | ||
176 | /* | |
177 | * rb tree support functions | |
178 | */ | |
179 | #define RB_NONE (2) | |
180 | #define RB_EMPTY(root) ((root)->rb_node == NULL) | |
181 | #define ON_RB(node) ((node)->rb_color != RB_NONE) | |
182 | #define RB_CLEAR(node) ((node)->rb_color = RB_NONE) | |
183 | #define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node) | |
184 | #define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)]) | |
185 | #define rq_rb_key(rq) (rq)->sector | |
186 | ||
187 | static struct deadline_rq * | |
188 | __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
189 | { | |
190 | struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node; | |
191 | struct rb_node *parent = NULL; | |
192 | struct deadline_rq *__drq; | |
193 | ||
194 | while (*p) { | |
195 | parent = *p; | |
196 | __drq = rb_entry_drq(parent); | |
197 | ||
198 | if (drq->rb_key < __drq->rb_key) | |
199 | p = &(*p)->rb_left; | |
200 | else if (drq->rb_key > __drq->rb_key) | |
201 | p = &(*p)->rb_right; | |
202 | else | |
203 | return __drq; | |
204 | } | |
205 | ||
206 | rb_link_node(&drq->rb_node, parent, p); | |
207 | return NULL; | |
208 | } | |
209 | ||
210 | static void | |
211 | deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
212 | { | |
213 | struct deadline_rq *__alias; | |
214 | ||
215 | drq->rb_key = rq_rb_key(drq->request); | |
216 | ||
217 | retry: | |
218 | __alias = __deadline_add_drq_rb(dd, drq); | |
219 | if (!__alias) { | |
220 | rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); | |
221 | return; | |
222 | } | |
223 | ||
224 | deadline_move_request(dd, __alias); | |
225 | goto retry; | |
226 | } | |
227 | ||
228 | static inline void | |
229 | deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
230 | { | |
231 | const int data_dir = rq_data_dir(drq->request); | |
232 | ||
233 | if (dd->next_drq[data_dir] == drq) { | |
234 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
235 | ||
236 | dd->next_drq[data_dir] = NULL; | |
237 | if (rbnext) | |
238 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
239 | } | |
240 | ||
b4878f24 JA |
241 | BUG_ON(!ON_RB(&drq->rb_node)); |
242 | rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); | |
243 | RB_CLEAR(&drq->rb_node); | |
1da177e4 LT |
244 | } |
245 | ||
246 | static struct request * | |
247 | deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir) | |
248 | { | |
249 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
250 | struct deadline_rq *drq; | |
251 | ||
252 | while (n) { | |
253 | drq = rb_entry_drq(n); | |
254 | ||
255 | if (sector < drq->rb_key) | |
256 | n = n->rb_left; | |
257 | else if (sector > drq->rb_key) | |
258 | n = n->rb_right; | |
259 | else | |
260 | return drq->request; | |
261 | } | |
262 | ||
263 | return NULL; | |
264 | } | |
265 | ||
266 | /* | |
267 | * deadline_find_first_drq finds the first (lowest sector numbered) request | |
268 | * for the specified data_dir. Used to sweep back to the start of the disk | |
269 | * (1-way elevator) after we process the last (highest sector) request. | |
270 | */ | |
271 | static struct deadline_rq * | |
272 | deadline_find_first_drq(struct deadline_data *dd, int data_dir) | |
273 | { | |
274 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
275 | ||
276 | for (;;) { | |
277 | if (n->rb_left == NULL) | |
278 | return rb_entry_drq(n); | |
279 | ||
280 | n = n->rb_left; | |
281 | } | |
282 | } | |
283 | ||
284 | /* | |
285 | * add drq to rbtree and fifo | |
286 | */ | |
b4878f24 | 287 | static void |
1da177e4 LT |
288 | deadline_add_request(struct request_queue *q, struct request *rq) |
289 | { | |
290 | struct deadline_data *dd = q->elevator->elevator_data; | |
291 | struct deadline_rq *drq = RQ_DATA(rq); | |
292 | ||
293 | const int data_dir = rq_data_dir(drq->request); | |
294 | ||
295 | deadline_add_drq_rb(dd, drq); | |
296 | /* | |
297 | * set expire time (only used for reads) and add to fifo list | |
298 | */ | |
299 | drq->expires = jiffies + dd->fifo_expire[data_dir]; | |
300 | list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]); | |
301 | ||
302 | if (rq_mergeable(rq)) { | |
303 | deadline_add_drq_hash(dd, drq); | |
304 | ||
305 | if (!q->last_merge) | |
306 | q->last_merge = rq; | |
307 | } | |
308 | } | |
309 | ||
310 | /* | |
311 | * remove rq from rbtree, fifo, and hash | |
312 | */ | |
313 | static void deadline_remove_request(request_queue_t *q, struct request *rq) | |
314 | { | |
315 | struct deadline_rq *drq = RQ_DATA(rq); | |
b4878f24 | 316 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 | 317 | |
b4878f24 JA |
318 | list_del_init(&drq->fifo); |
319 | deadline_remove_merge_hints(q, drq); | |
320 | deadline_del_drq_rb(dd, drq); | |
1da177e4 LT |
321 | } |
322 | ||
323 | static int | |
324 | deadline_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
325 | { | |
326 | struct deadline_data *dd = q->elevator->elevator_data; | |
327 | struct request *__rq; | |
328 | int ret; | |
329 | ||
330 | /* | |
331 | * try last_merge to avoid going to hash | |
332 | */ | |
333 | ret = elv_try_last_merge(q, bio); | |
334 | if (ret != ELEVATOR_NO_MERGE) { | |
335 | __rq = q->last_merge; | |
336 | goto out_insert; | |
337 | } | |
338 | ||
339 | /* | |
340 | * see if the merge hash can satisfy a back merge | |
341 | */ | |
342 | __rq = deadline_find_drq_hash(dd, bio->bi_sector); | |
343 | if (__rq) { | |
344 | BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); | |
345 | ||
346 | if (elv_rq_merge_ok(__rq, bio)) { | |
347 | ret = ELEVATOR_BACK_MERGE; | |
348 | goto out; | |
349 | } | |
350 | } | |
351 | ||
352 | /* | |
353 | * check for front merge | |
354 | */ | |
355 | if (dd->front_merges) { | |
356 | sector_t rb_key = bio->bi_sector + bio_sectors(bio); | |
357 | ||
358 | __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio)); | |
359 | if (__rq) { | |
360 | BUG_ON(rb_key != rq_rb_key(__rq)); | |
361 | ||
362 | if (elv_rq_merge_ok(__rq, bio)) { | |
363 | ret = ELEVATOR_FRONT_MERGE; | |
364 | goto out; | |
365 | } | |
366 | } | |
367 | } | |
368 | ||
369 | return ELEVATOR_NO_MERGE; | |
370 | out: | |
371 | q->last_merge = __rq; | |
372 | out_insert: | |
373 | if (ret) | |
374 | deadline_hot_drq_hash(dd, RQ_DATA(__rq)); | |
375 | *req = __rq; | |
376 | return ret; | |
377 | } | |
378 | ||
379 | static void deadline_merged_request(request_queue_t *q, struct request *req) | |
380 | { | |
381 | struct deadline_data *dd = q->elevator->elevator_data; | |
382 | struct deadline_rq *drq = RQ_DATA(req); | |
383 | ||
384 | /* | |
385 | * hash always needs to be repositioned, key is end sector | |
386 | */ | |
387 | deadline_del_drq_hash(drq); | |
388 | deadline_add_drq_hash(dd, drq); | |
389 | ||
390 | /* | |
391 | * if the merge was a front merge, we need to reposition request | |
392 | */ | |
393 | if (rq_rb_key(req) != drq->rb_key) { | |
394 | deadline_del_drq_rb(dd, drq); | |
395 | deadline_add_drq_rb(dd, drq); | |
396 | } | |
397 | ||
398 | q->last_merge = req; | |
399 | } | |
400 | ||
401 | static void | |
402 | deadline_merged_requests(request_queue_t *q, struct request *req, | |
403 | struct request *next) | |
404 | { | |
405 | struct deadline_data *dd = q->elevator->elevator_data; | |
406 | struct deadline_rq *drq = RQ_DATA(req); | |
407 | struct deadline_rq *dnext = RQ_DATA(next); | |
408 | ||
409 | BUG_ON(!drq); | |
410 | BUG_ON(!dnext); | |
411 | ||
412 | /* | |
413 | * reposition drq (this is the merged request) in hash, and in rbtree | |
414 | * in case of a front merge | |
415 | */ | |
416 | deadline_del_drq_hash(drq); | |
417 | deadline_add_drq_hash(dd, drq); | |
418 | ||
419 | if (rq_rb_key(req) != drq->rb_key) { | |
420 | deadline_del_drq_rb(dd, drq); | |
421 | deadline_add_drq_rb(dd, drq); | |
422 | } | |
423 | ||
424 | /* | |
425 | * if dnext expires before drq, assign its expire time to drq | |
426 | * and move into dnext position (dnext will be deleted) in fifo | |
427 | */ | |
428 | if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) { | |
429 | if (time_before(dnext->expires, drq->expires)) { | |
430 | list_move(&drq->fifo, &dnext->fifo); | |
431 | drq->expires = dnext->expires; | |
432 | } | |
433 | } | |
434 | ||
435 | /* | |
436 | * kill knowledge of next, this one is a goner | |
437 | */ | |
438 | deadline_remove_request(q, next); | |
439 | } | |
440 | ||
441 | /* | |
442 | * move request from sort list to dispatch queue. | |
443 | */ | |
444 | static inline void | |
445 | deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq) | |
446 | { | |
447 | request_queue_t *q = drq->request->q; | |
448 | ||
449 | deadline_remove_request(q, drq->request); | |
b4878f24 | 450 | elv_dispatch_add_tail(q, drq->request); |
1da177e4 LT |
451 | } |
452 | ||
453 | /* | |
454 | * move an entry to dispatch queue | |
455 | */ | |
456 | static void | |
457 | deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq) | |
458 | { | |
459 | const int data_dir = rq_data_dir(drq->request); | |
460 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
461 | ||
462 | dd->next_drq[READ] = NULL; | |
463 | dd->next_drq[WRITE] = NULL; | |
464 | ||
465 | if (rbnext) | |
466 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
467 | ||
468 | dd->last_sector = drq->request->sector + drq->request->nr_sectors; | |
469 | ||
470 | /* | |
471 | * take it off the sort and fifo list, move | |
472 | * to dispatch queue | |
473 | */ | |
474 | deadline_move_to_dispatch(dd, drq); | |
475 | } | |
476 | ||
477 | #define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo) | |
478 | ||
479 | /* | |
480 | * deadline_check_fifo returns 0 if there are no expired reads on the fifo, | |
481 | * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) | |
482 | */ | |
483 | static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) | |
484 | { | |
485 | struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next); | |
486 | ||
487 | /* | |
488 | * drq is expired! | |
489 | */ | |
490 | if (time_after(jiffies, drq->expires)) | |
491 | return 1; | |
492 | ||
493 | return 0; | |
494 | } | |
495 | ||
496 | /* | |
497 | * deadline_dispatch_requests selects the best request according to | |
498 | * read/write expire, fifo_batch, etc | |
499 | */ | |
b4878f24 | 500 | static int deadline_dispatch_requests(request_queue_t *q, int force) |
1da177e4 | 501 | { |
b4878f24 | 502 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 LT |
503 | const int reads = !list_empty(&dd->fifo_list[READ]); |
504 | const int writes = !list_empty(&dd->fifo_list[WRITE]); | |
505 | struct deadline_rq *drq; | |
4b0dc07e | 506 | int data_dir; |
1da177e4 LT |
507 | |
508 | /* | |
509 | * batches are currently reads XOR writes | |
510 | */ | |
9d5c1e1b AM |
511 | if (dd->next_drq[WRITE]) |
512 | drq = dd->next_drq[WRITE]; | |
513 | else | |
514 | drq = dd->next_drq[READ]; | |
1da177e4 LT |
515 | |
516 | if (drq) { | |
517 | /* we have a "next request" */ | |
518 | ||
519 | if (dd->last_sector != drq->request->sector) | |
520 | /* end the batch on a non sequential request */ | |
521 | dd->batching += dd->fifo_batch; | |
522 | ||
523 | if (dd->batching < dd->fifo_batch) | |
524 | /* we are still entitled to batch */ | |
525 | goto dispatch_request; | |
526 | } | |
527 | ||
528 | /* | |
529 | * at this point we are not running a batch. select the appropriate | |
530 | * data direction (read / write) | |
531 | */ | |
532 | ||
533 | if (reads) { | |
534 | BUG_ON(RB_EMPTY(&dd->sort_list[READ])); | |
535 | ||
536 | if (writes && (dd->starved++ >= dd->writes_starved)) | |
537 | goto dispatch_writes; | |
538 | ||
539 | data_dir = READ; | |
1da177e4 LT |
540 | |
541 | goto dispatch_find_request; | |
542 | } | |
543 | ||
544 | /* | |
545 | * there are either no reads or writes have been starved | |
546 | */ | |
547 | ||
548 | if (writes) { | |
549 | dispatch_writes: | |
550 | BUG_ON(RB_EMPTY(&dd->sort_list[WRITE])); | |
551 | ||
552 | dd->starved = 0; | |
553 | ||
554 | data_dir = WRITE; | |
1da177e4 LT |
555 | |
556 | goto dispatch_find_request; | |
557 | } | |
558 | ||
559 | return 0; | |
560 | ||
561 | dispatch_find_request: | |
562 | /* | |
563 | * we are not running a batch, find best request for selected data_dir | |
564 | */ | |
565 | if (deadline_check_fifo(dd, data_dir)) { | |
566 | /* An expired request exists - satisfy it */ | |
567 | dd->batching = 0; | |
568 | drq = list_entry_fifo(dd->fifo_list[data_dir].next); | |
569 | ||
570 | } else if (dd->next_drq[data_dir]) { | |
571 | /* | |
572 | * The last req was the same dir and we have a next request in | |
573 | * sort order. No expired requests so continue on from here. | |
574 | */ | |
575 | drq = dd->next_drq[data_dir]; | |
576 | } else { | |
577 | /* | |
578 | * The last req was the other direction or we have run out of | |
579 | * higher-sectored requests. Go back to the lowest sectored | |
580 | * request (1 way elevator) and start a new batch. | |
581 | */ | |
582 | dd->batching = 0; | |
583 | drq = deadline_find_first_drq(dd, data_dir); | |
584 | } | |
585 | ||
586 | dispatch_request: | |
587 | /* | |
588 | * drq is the selected appropriate request. | |
589 | */ | |
590 | dd->batching++; | |
591 | deadline_move_request(dd, drq); | |
592 | ||
593 | return 1; | |
594 | } | |
595 | ||
1da177e4 LT |
596 | static int deadline_queue_empty(request_queue_t *q) |
597 | { | |
598 | struct deadline_data *dd = q->elevator->elevator_data; | |
599 | ||
b4878f24 JA |
600 | return list_empty(&dd->fifo_list[WRITE]) |
601 | && list_empty(&dd->fifo_list[READ]); | |
1da177e4 LT |
602 | } |
603 | ||
604 | static struct request * | |
605 | deadline_former_request(request_queue_t *q, struct request *rq) | |
606 | { | |
607 | struct deadline_rq *drq = RQ_DATA(rq); | |
608 | struct rb_node *rbprev = rb_prev(&drq->rb_node); | |
609 | ||
610 | if (rbprev) | |
611 | return rb_entry_drq(rbprev)->request; | |
612 | ||
613 | return NULL; | |
614 | } | |
615 | ||
616 | static struct request * | |
617 | deadline_latter_request(request_queue_t *q, struct request *rq) | |
618 | { | |
619 | struct deadline_rq *drq = RQ_DATA(rq); | |
620 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
621 | ||
622 | if (rbnext) | |
623 | return rb_entry_drq(rbnext)->request; | |
624 | ||
625 | return NULL; | |
626 | } | |
627 | ||
628 | static void deadline_exit_queue(elevator_t *e) | |
629 | { | |
630 | struct deadline_data *dd = e->elevator_data; | |
631 | ||
632 | BUG_ON(!list_empty(&dd->fifo_list[READ])); | |
633 | BUG_ON(!list_empty(&dd->fifo_list[WRITE])); | |
634 | ||
635 | mempool_destroy(dd->drq_pool); | |
636 | kfree(dd->hash); | |
637 | kfree(dd); | |
638 | } | |
639 | ||
640 | /* | |
641 | * initialize elevator private data (deadline_data), and alloc a drq for | |
642 | * each request on the free lists | |
643 | */ | |
644 | static int deadline_init_queue(request_queue_t *q, elevator_t *e) | |
645 | { | |
646 | struct deadline_data *dd; | |
647 | int i; | |
648 | ||
649 | if (!drq_pool) | |
650 | return -ENOMEM; | |
651 | ||
1946089a | 652 | dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node); |
1da177e4 LT |
653 | if (!dd) |
654 | return -ENOMEM; | |
655 | memset(dd, 0, sizeof(*dd)); | |
656 | ||
1946089a CL |
657 | dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES, |
658 | GFP_KERNEL, q->node); | |
1da177e4 LT |
659 | if (!dd->hash) { |
660 | kfree(dd); | |
661 | return -ENOMEM; | |
662 | } | |
663 | ||
1946089a CL |
664 | dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
665 | mempool_free_slab, drq_pool, q->node); | |
1da177e4 LT |
666 | if (!dd->drq_pool) { |
667 | kfree(dd->hash); | |
668 | kfree(dd); | |
669 | return -ENOMEM; | |
670 | } | |
671 | ||
672 | for (i = 0; i < DL_HASH_ENTRIES; i++) | |
673 | INIT_LIST_HEAD(&dd->hash[i]); | |
674 | ||
675 | INIT_LIST_HEAD(&dd->fifo_list[READ]); | |
676 | INIT_LIST_HEAD(&dd->fifo_list[WRITE]); | |
677 | dd->sort_list[READ] = RB_ROOT; | |
678 | dd->sort_list[WRITE] = RB_ROOT; | |
1da177e4 LT |
679 | dd->fifo_expire[READ] = read_expire; |
680 | dd->fifo_expire[WRITE] = write_expire; | |
681 | dd->writes_starved = writes_starved; | |
682 | dd->front_merges = 1; | |
683 | dd->fifo_batch = fifo_batch; | |
684 | e->elevator_data = dd; | |
685 | return 0; | |
686 | } | |
687 | ||
688 | static void deadline_put_request(request_queue_t *q, struct request *rq) | |
689 | { | |
690 | struct deadline_data *dd = q->elevator->elevator_data; | |
691 | struct deadline_rq *drq = RQ_DATA(rq); | |
692 | ||
b4878f24 JA |
693 | mempool_free(drq, dd->drq_pool); |
694 | rq->elevator_private = NULL; | |
1da177e4 LT |
695 | } |
696 | ||
697 | static int | |
22e2c507 JA |
698 | deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
699 | int gfp_mask) | |
1da177e4 LT |
700 | { |
701 | struct deadline_data *dd = q->elevator->elevator_data; | |
702 | struct deadline_rq *drq; | |
703 | ||
704 | drq = mempool_alloc(dd->drq_pool, gfp_mask); | |
705 | if (drq) { | |
706 | memset(drq, 0, sizeof(*drq)); | |
707 | RB_CLEAR(&drq->rb_node); | |
708 | drq->request = rq; | |
709 | ||
710 | INIT_LIST_HEAD(&drq->hash); | |
711 | drq->on_hash = 0; | |
712 | ||
713 | INIT_LIST_HEAD(&drq->fifo); | |
714 | ||
715 | rq->elevator_private = drq; | |
716 | return 0; | |
717 | } | |
718 | ||
719 | return 1; | |
720 | } | |
721 | ||
722 | /* | |
723 | * sysfs parts below | |
724 | */ | |
725 | struct deadline_fs_entry { | |
726 | struct attribute attr; | |
727 | ssize_t (*show)(struct deadline_data *, char *); | |
728 | ssize_t (*store)(struct deadline_data *, const char *, size_t); | |
729 | }; | |
730 | ||
731 | static ssize_t | |
732 | deadline_var_show(int var, char *page) | |
733 | { | |
734 | return sprintf(page, "%d\n", var); | |
735 | } | |
736 | ||
737 | static ssize_t | |
738 | deadline_var_store(int *var, const char *page, size_t count) | |
739 | { | |
740 | char *p = (char *) page; | |
741 | ||
742 | *var = simple_strtol(p, &p, 10); | |
743 | return count; | |
744 | } | |
745 | ||
746 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
747 | static ssize_t __FUNC(struct deadline_data *dd, char *page) \ | |
748 | { \ | |
749 | int __data = __VAR; \ | |
750 | if (__CONV) \ | |
751 | __data = jiffies_to_msecs(__data); \ | |
752 | return deadline_var_show(__data, (page)); \ | |
753 | } | |
754 | SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1); | |
755 | SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1); | |
756 | SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0); | |
757 | SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0); | |
758 | SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0); | |
759 | #undef SHOW_FUNCTION | |
760 | ||
761 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
762 | static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \ | |
763 | { \ | |
764 | int __data; \ | |
765 | int ret = deadline_var_store(&__data, (page), count); \ | |
766 | if (__data < (MIN)) \ | |
767 | __data = (MIN); \ | |
768 | else if (__data > (MAX)) \ | |
769 | __data = (MAX); \ | |
770 | if (__CONV) \ | |
771 | *(__PTR) = msecs_to_jiffies(__data); \ | |
772 | else \ | |
773 | *(__PTR) = __data; \ | |
774 | return ret; \ | |
775 | } | |
776 | STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); | |
777 | STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); | |
778 | STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); | |
779 | STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0); | |
780 | STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0); | |
781 | #undef STORE_FUNCTION | |
782 | ||
783 | static struct deadline_fs_entry deadline_readexpire_entry = { | |
784 | .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR }, | |
785 | .show = deadline_readexpire_show, | |
786 | .store = deadline_readexpire_store, | |
787 | }; | |
788 | static struct deadline_fs_entry deadline_writeexpire_entry = { | |
789 | .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR }, | |
790 | .show = deadline_writeexpire_show, | |
791 | .store = deadline_writeexpire_store, | |
792 | }; | |
793 | static struct deadline_fs_entry deadline_writesstarved_entry = { | |
794 | .attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR }, | |
795 | .show = deadline_writesstarved_show, | |
796 | .store = deadline_writesstarved_store, | |
797 | }; | |
798 | static struct deadline_fs_entry deadline_frontmerges_entry = { | |
799 | .attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR }, | |
800 | .show = deadline_frontmerges_show, | |
801 | .store = deadline_frontmerges_store, | |
802 | }; | |
803 | static struct deadline_fs_entry deadline_fifobatch_entry = { | |
804 | .attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR }, | |
805 | .show = deadline_fifobatch_show, | |
806 | .store = deadline_fifobatch_store, | |
807 | }; | |
808 | ||
809 | static struct attribute *default_attrs[] = { | |
810 | &deadline_readexpire_entry.attr, | |
811 | &deadline_writeexpire_entry.attr, | |
812 | &deadline_writesstarved_entry.attr, | |
813 | &deadline_frontmerges_entry.attr, | |
814 | &deadline_fifobatch_entry.attr, | |
815 | NULL, | |
816 | }; | |
817 | ||
818 | #define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr) | |
819 | ||
820 | static ssize_t | |
821 | deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
822 | { | |
823 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
824 | struct deadline_fs_entry *entry = to_deadline(attr); | |
825 | ||
826 | if (!entry->show) | |
6c1852a0 | 827 | return -EIO; |
1da177e4 LT |
828 | |
829 | return entry->show(e->elevator_data, page); | |
830 | } | |
831 | ||
832 | static ssize_t | |
833 | deadline_attr_store(struct kobject *kobj, struct attribute *attr, | |
834 | const char *page, size_t length) | |
835 | { | |
836 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
837 | struct deadline_fs_entry *entry = to_deadline(attr); | |
838 | ||
839 | if (!entry->store) | |
6c1852a0 | 840 | return -EIO; |
1da177e4 LT |
841 | |
842 | return entry->store(e->elevator_data, page, length); | |
843 | } | |
844 | ||
845 | static struct sysfs_ops deadline_sysfs_ops = { | |
846 | .show = deadline_attr_show, | |
847 | .store = deadline_attr_store, | |
848 | }; | |
849 | ||
850 | static struct kobj_type deadline_ktype = { | |
851 | .sysfs_ops = &deadline_sysfs_ops, | |
852 | .default_attrs = default_attrs, | |
853 | }; | |
854 | ||
855 | static struct elevator_type iosched_deadline = { | |
856 | .ops = { | |
857 | .elevator_merge_fn = deadline_merge, | |
858 | .elevator_merged_fn = deadline_merged_request, | |
859 | .elevator_merge_req_fn = deadline_merged_requests, | |
b4878f24 JA |
860 | .elevator_dispatch_fn = deadline_dispatch_requests, |
861 | .elevator_add_req_fn = deadline_add_request, | |
1da177e4 LT |
862 | .elevator_queue_empty_fn = deadline_queue_empty, |
863 | .elevator_former_req_fn = deadline_former_request, | |
864 | .elevator_latter_req_fn = deadline_latter_request, | |
865 | .elevator_set_req_fn = deadline_set_request, | |
866 | .elevator_put_req_fn = deadline_put_request, | |
867 | .elevator_init_fn = deadline_init_queue, | |
868 | .elevator_exit_fn = deadline_exit_queue, | |
869 | }, | |
870 | ||
871 | .elevator_ktype = &deadline_ktype, | |
872 | .elevator_name = "deadline", | |
873 | .elevator_owner = THIS_MODULE, | |
874 | }; | |
875 | ||
876 | static int __init deadline_init(void) | |
877 | { | |
878 | int ret; | |
879 | ||
880 | drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq), | |
881 | 0, 0, NULL, NULL); | |
882 | ||
883 | if (!drq_pool) | |
884 | return -ENOMEM; | |
885 | ||
886 | ret = elv_register(&iosched_deadline); | |
887 | if (ret) | |
888 | kmem_cache_destroy(drq_pool); | |
889 | ||
890 | return ret; | |
891 | } | |
892 | ||
893 | static void __exit deadline_exit(void) | |
894 | { | |
895 | kmem_cache_destroy(drq_pool); | |
896 | elv_unregister(&iosched_deadline); | |
897 | } | |
898 | ||
899 | module_init(deadline_init); | |
900 | module_exit(deadline_exit); | |
901 | ||
902 | MODULE_AUTHOR("Jens Axboe"); | |
903 | MODULE_LICENSE("GPL"); | |
904 | MODULE_DESCRIPTION("deadline IO scheduler"); |