Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Deadline i/o scheduler. |
3 | * | |
4 | * Copyright (C) 2002 Jens Axboe <axboe@suse.de> | |
5 | */ | |
6 | #include <linux/kernel.h> | |
7 | #include <linux/fs.h> | |
8 | #include <linux/blkdev.h> | |
9 | #include <linux/elevator.h> | |
10 | #include <linux/bio.h> | |
11 | #include <linux/config.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/compiler.h> | |
16 | #include <linux/hash.h> | |
17 | #include <linux/rbtree.h> | |
18 | ||
19 | /* | |
20 | * See Documentation/block/deadline-iosched.txt | |
21 | */ | |
64100099 AV |
22 | static const int read_expire = HZ / 2; /* max time before a read is submitted. */ |
23 | static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ | |
24 | static const int writes_starved = 2; /* max times reads can starve a write */ | |
25 | static const int fifo_batch = 16; /* # of sequential requests treated as one | |
1da177e4 LT |
26 | by the above parameters. For throughput. */ |
27 | ||
28 | static const int deadline_hash_shift = 5; | |
29 | #define DL_HASH_BLOCK(sec) ((sec) >> 3) | |
30 | #define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift)) | |
31 | #define DL_HASH_ENTRIES (1 << deadline_hash_shift) | |
32 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
33 | #define list_entry_hash(ptr) list_entry((ptr), struct deadline_rq, hash) | |
34 | #define ON_HASH(drq) (drq)->on_hash | |
35 | ||
36 | struct deadline_data { | |
37 | /* | |
38 | * run time data | |
39 | */ | |
40 | ||
41 | /* | |
42 | * requests (deadline_rq s) are present on both sort_list and fifo_list | |
43 | */ | |
44 | struct rb_root sort_list[2]; | |
45 | struct list_head fifo_list[2]; | |
46 | ||
47 | /* | |
48 | * next in sort order. read, write or both are NULL | |
49 | */ | |
50 | struct deadline_rq *next_drq[2]; | |
1da177e4 LT |
51 | struct list_head *hash; /* request hash */ |
52 | unsigned int batching; /* number of sequential requests made */ | |
53 | sector_t last_sector; /* head position */ | |
54 | unsigned int starved; /* times reads have starved writes */ | |
55 | ||
56 | /* | |
57 | * settings that change how the i/o scheduler behaves | |
58 | */ | |
59 | int fifo_expire[2]; | |
60 | int fifo_batch; | |
61 | int writes_starved; | |
62 | int front_merges; | |
63 | ||
64 | mempool_t *drq_pool; | |
65 | }; | |
66 | ||
67 | /* | |
68 | * pre-request data. | |
69 | */ | |
70 | struct deadline_rq { | |
71 | /* | |
72 | * rbtree index, key is the starting offset | |
73 | */ | |
74 | struct rb_node rb_node; | |
75 | sector_t rb_key; | |
76 | ||
77 | struct request *request; | |
78 | ||
79 | /* | |
80 | * request hash, key is the ending offset (for back merge lookup) | |
81 | */ | |
82 | struct list_head hash; | |
83 | char on_hash; | |
84 | ||
85 | /* | |
86 | * expire fifo | |
87 | */ | |
88 | struct list_head fifo; | |
89 | unsigned long expires; | |
90 | }; | |
91 | ||
92 | static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq); | |
93 | ||
94 | static kmem_cache_t *drq_pool; | |
95 | ||
96 | #define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private) | |
97 | ||
98 | /* | |
99 | * the back merge hash support functions | |
100 | */ | |
101 | static inline void __deadline_del_drq_hash(struct deadline_rq *drq) | |
102 | { | |
103 | drq->on_hash = 0; | |
104 | list_del_init(&drq->hash); | |
105 | } | |
106 | ||
107 | static inline void deadline_del_drq_hash(struct deadline_rq *drq) | |
108 | { | |
109 | if (ON_HASH(drq)) | |
110 | __deadline_del_drq_hash(drq); | |
111 | } | |
112 | ||
1da177e4 LT |
113 | static inline void |
114 | deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
115 | { | |
116 | struct request *rq = drq->request; | |
117 | ||
118 | BUG_ON(ON_HASH(drq)); | |
119 | ||
120 | drq->on_hash = 1; | |
121 | list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]); | |
122 | } | |
123 | ||
124 | /* | |
125 | * move hot entry to front of chain | |
126 | */ | |
127 | static inline void | |
128 | deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
129 | { | |
130 | struct request *rq = drq->request; | |
131 | struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))]; | |
132 | ||
133 | if (ON_HASH(drq) && drq->hash.prev != head) { | |
134 | list_del(&drq->hash); | |
135 | list_add(&drq->hash, head); | |
136 | } | |
137 | } | |
138 | ||
139 | static struct request * | |
140 | deadline_find_drq_hash(struct deadline_data *dd, sector_t offset) | |
141 | { | |
142 | struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)]; | |
143 | struct list_head *entry, *next = hash_list->next; | |
144 | ||
145 | while ((entry = next) != hash_list) { | |
146 | struct deadline_rq *drq = list_entry_hash(entry); | |
147 | struct request *__rq = drq->request; | |
148 | ||
149 | next = entry->next; | |
150 | ||
151 | BUG_ON(!ON_HASH(drq)); | |
152 | ||
153 | if (!rq_mergeable(__rq)) { | |
154 | __deadline_del_drq_hash(drq); | |
155 | continue; | |
156 | } | |
157 | ||
158 | if (rq_hash_key(__rq) == offset) | |
159 | return __rq; | |
160 | } | |
161 | ||
162 | return NULL; | |
163 | } | |
164 | ||
165 | /* | |
166 | * rb tree support functions | |
167 | */ | |
168 | #define RB_NONE (2) | |
169 | #define RB_EMPTY(root) ((root)->rb_node == NULL) | |
170 | #define ON_RB(node) ((node)->rb_color != RB_NONE) | |
171 | #define RB_CLEAR(node) ((node)->rb_color = RB_NONE) | |
172 | #define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node) | |
173 | #define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)]) | |
174 | #define rq_rb_key(rq) (rq)->sector | |
175 | ||
176 | static struct deadline_rq * | |
177 | __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
178 | { | |
179 | struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node; | |
180 | struct rb_node *parent = NULL; | |
181 | struct deadline_rq *__drq; | |
182 | ||
183 | while (*p) { | |
184 | parent = *p; | |
185 | __drq = rb_entry_drq(parent); | |
186 | ||
187 | if (drq->rb_key < __drq->rb_key) | |
188 | p = &(*p)->rb_left; | |
189 | else if (drq->rb_key > __drq->rb_key) | |
190 | p = &(*p)->rb_right; | |
191 | else | |
192 | return __drq; | |
193 | } | |
194 | ||
195 | rb_link_node(&drq->rb_node, parent, p); | |
196 | return NULL; | |
197 | } | |
198 | ||
199 | static void | |
200 | deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
201 | { | |
202 | struct deadline_rq *__alias; | |
203 | ||
204 | drq->rb_key = rq_rb_key(drq->request); | |
205 | ||
206 | retry: | |
207 | __alias = __deadline_add_drq_rb(dd, drq); | |
208 | if (!__alias) { | |
209 | rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); | |
210 | return; | |
211 | } | |
212 | ||
213 | deadline_move_request(dd, __alias); | |
214 | goto retry; | |
215 | } | |
216 | ||
217 | static inline void | |
218 | deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
219 | { | |
220 | const int data_dir = rq_data_dir(drq->request); | |
221 | ||
222 | if (dd->next_drq[data_dir] == drq) { | |
223 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
224 | ||
225 | dd->next_drq[data_dir] = NULL; | |
226 | if (rbnext) | |
227 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
228 | } | |
229 | ||
b4878f24 JA |
230 | BUG_ON(!ON_RB(&drq->rb_node)); |
231 | rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); | |
232 | RB_CLEAR(&drq->rb_node); | |
1da177e4 LT |
233 | } |
234 | ||
235 | static struct request * | |
236 | deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir) | |
237 | { | |
238 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
239 | struct deadline_rq *drq; | |
240 | ||
241 | while (n) { | |
242 | drq = rb_entry_drq(n); | |
243 | ||
244 | if (sector < drq->rb_key) | |
245 | n = n->rb_left; | |
246 | else if (sector > drq->rb_key) | |
247 | n = n->rb_right; | |
248 | else | |
249 | return drq->request; | |
250 | } | |
251 | ||
252 | return NULL; | |
253 | } | |
254 | ||
255 | /* | |
256 | * deadline_find_first_drq finds the first (lowest sector numbered) request | |
257 | * for the specified data_dir. Used to sweep back to the start of the disk | |
258 | * (1-way elevator) after we process the last (highest sector) request. | |
259 | */ | |
260 | static struct deadline_rq * | |
261 | deadline_find_first_drq(struct deadline_data *dd, int data_dir) | |
262 | { | |
263 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
264 | ||
265 | for (;;) { | |
266 | if (n->rb_left == NULL) | |
267 | return rb_entry_drq(n); | |
268 | ||
269 | n = n->rb_left; | |
270 | } | |
271 | } | |
272 | ||
273 | /* | |
274 | * add drq to rbtree and fifo | |
275 | */ | |
b4878f24 | 276 | static void |
1da177e4 LT |
277 | deadline_add_request(struct request_queue *q, struct request *rq) |
278 | { | |
279 | struct deadline_data *dd = q->elevator->elevator_data; | |
280 | struct deadline_rq *drq = RQ_DATA(rq); | |
281 | ||
282 | const int data_dir = rq_data_dir(drq->request); | |
283 | ||
284 | deadline_add_drq_rb(dd, drq); | |
285 | /* | |
286 | * set expire time (only used for reads) and add to fifo list | |
287 | */ | |
288 | drq->expires = jiffies + dd->fifo_expire[data_dir]; | |
289 | list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]); | |
290 | ||
98b11471 | 291 | if (rq_mergeable(rq)) |
1da177e4 | 292 | deadline_add_drq_hash(dd, drq); |
1da177e4 LT |
293 | } |
294 | ||
295 | /* | |
296 | * remove rq from rbtree, fifo, and hash | |
297 | */ | |
298 | static void deadline_remove_request(request_queue_t *q, struct request *rq) | |
299 | { | |
300 | struct deadline_rq *drq = RQ_DATA(rq); | |
b4878f24 | 301 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 | 302 | |
b4878f24 | 303 | list_del_init(&drq->fifo); |
b4878f24 | 304 | deadline_del_drq_rb(dd, drq); |
98b11471 | 305 | deadline_del_drq_hash(drq); |
1da177e4 LT |
306 | } |
307 | ||
308 | static int | |
309 | deadline_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
310 | { | |
311 | struct deadline_data *dd = q->elevator->elevator_data; | |
312 | struct request *__rq; | |
313 | int ret; | |
314 | ||
1da177e4 LT |
315 | /* |
316 | * see if the merge hash can satisfy a back merge | |
317 | */ | |
318 | __rq = deadline_find_drq_hash(dd, bio->bi_sector); | |
319 | if (__rq) { | |
320 | BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); | |
321 | ||
322 | if (elv_rq_merge_ok(__rq, bio)) { | |
323 | ret = ELEVATOR_BACK_MERGE; | |
324 | goto out; | |
325 | } | |
326 | } | |
327 | ||
328 | /* | |
329 | * check for front merge | |
330 | */ | |
331 | if (dd->front_merges) { | |
332 | sector_t rb_key = bio->bi_sector + bio_sectors(bio); | |
333 | ||
334 | __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio)); | |
335 | if (__rq) { | |
336 | BUG_ON(rb_key != rq_rb_key(__rq)); | |
337 | ||
338 | if (elv_rq_merge_ok(__rq, bio)) { | |
339 | ret = ELEVATOR_FRONT_MERGE; | |
340 | goto out; | |
341 | } | |
342 | } | |
343 | } | |
344 | ||
345 | return ELEVATOR_NO_MERGE; | |
346 | out: | |
1da177e4 LT |
347 | if (ret) |
348 | deadline_hot_drq_hash(dd, RQ_DATA(__rq)); | |
349 | *req = __rq; | |
350 | return ret; | |
351 | } | |
352 | ||
353 | static void deadline_merged_request(request_queue_t *q, struct request *req) | |
354 | { | |
355 | struct deadline_data *dd = q->elevator->elevator_data; | |
356 | struct deadline_rq *drq = RQ_DATA(req); | |
357 | ||
358 | /* | |
359 | * hash always needs to be repositioned, key is end sector | |
360 | */ | |
361 | deadline_del_drq_hash(drq); | |
362 | deadline_add_drq_hash(dd, drq); | |
363 | ||
364 | /* | |
365 | * if the merge was a front merge, we need to reposition request | |
366 | */ | |
367 | if (rq_rb_key(req) != drq->rb_key) { | |
368 | deadline_del_drq_rb(dd, drq); | |
369 | deadline_add_drq_rb(dd, drq); | |
370 | } | |
1da177e4 LT |
371 | } |
372 | ||
373 | static void | |
374 | deadline_merged_requests(request_queue_t *q, struct request *req, | |
375 | struct request *next) | |
376 | { | |
377 | struct deadline_data *dd = q->elevator->elevator_data; | |
378 | struct deadline_rq *drq = RQ_DATA(req); | |
379 | struct deadline_rq *dnext = RQ_DATA(next); | |
380 | ||
381 | BUG_ON(!drq); | |
382 | BUG_ON(!dnext); | |
383 | ||
384 | /* | |
385 | * reposition drq (this is the merged request) in hash, and in rbtree | |
386 | * in case of a front merge | |
387 | */ | |
388 | deadline_del_drq_hash(drq); | |
389 | deadline_add_drq_hash(dd, drq); | |
390 | ||
391 | if (rq_rb_key(req) != drq->rb_key) { | |
392 | deadline_del_drq_rb(dd, drq); | |
393 | deadline_add_drq_rb(dd, drq); | |
394 | } | |
395 | ||
396 | /* | |
397 | * if dnext expires before drq, assign its expire time to drq | |
398 | * and move into dnext position (dnext will be deleted) in fifo | |
399 | */ | |
400 | if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) { | |
401 | if (time_before(dnext->expires, drq->expires)) { | |
402 | list_move(&drq->fifo, &dnext->fifo); | |
403 | drq->expires = dnext->expires; | |
404 | } | |
405 | } | |
406 | ||
407 | /* | |
408 | * kill knowledge of next, this one is a goner | |
409 | */ | |
410 | deadline_remove_request(q, next); | |
411 | } | |
412 | ||
413 | /* | |
414 | * move request from sort list to dispatch queue. | |
415 | */ | |
416 | static inline void | |
417 | deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq) | |
418 | { | |
419 | request_queue_t *q = drq->request->q; | |
420 | ||
421 | deadline_remove_request(q, drq->request); | |
b4878f24 | 422 | elv_dispatch_add_tail(q, drq->request); |
1da177e4 LT |
423 | } |
424 | ||
425 | /* | |
426 | * move an entry to dispatch queue | |
427 | */ | |
428 | static void | |
429 | deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq) | |
430 | { | |
431 | const int data_dir = rq_data_dir(drq->request); | |
432 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
433 | ||
434 | dd->next_drq[READ] = NULL; | |
435 | dd->next_drq[WRITE] = NULL; | |
436 | ||
437 | if (rbnext) | |
438 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
439 | ||
440 | dd->last_sector = drq->request->sector + drq->request->nr_sectors; | |
441 | ||
442 | /* | |
443 | * take it off the sort and fifo list, move | |
444 | * to dispatch queue | |
445 | */ | |
446 | deadline_move_to_dispatch(dd, drq); | |
447 | } | |
448 | ||
449 | #define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo) | |
450 | ||
451 | /* | |
452 | * deadline_check_fifo returns 0 if there are no expired reads on the fifo, | |
453 | * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) | |
454 | */ | |
455 | static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) | |
456 | { | |
457 | struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next); | |
458 | ||
459 | /* | |
460 | * drq is expired! | |
461 | */ | |
462 | if (time_after(jiffies, drq->expires)) | |
463 | return 1; | |
464 | ||
465 | return 0; | |
466 | } | |
467 | ||
468 | /* | |
469 | * deadline_dispatch_requests selects the best request according to | |
470 | * read/write expire, fifo_batch, etc | |
471 | */ | |
b4878f24 | 472 | static int deadline_dispatch_requests(request_queue_t *q, int force) |
1da177e4 | 473 | { |
b4878f24 | 474 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 LT |
475 | const int reads = !list_empty(&dd->fifo_list[READ]); |
476 | const int writes = !list_empty(&dd->fifo_list[WRITE]); | |
477 | struct deadline_rq *drq; | |
4b0dc07e | 478 | int data_dir; |
1da177e4 LT |
479 | |
480 | /* | |
481 | * batches are currently reads XOR writes | |
482 | */ | |
9d5c1e1b AM |
483 | if (dd->next_drq[WRITE]) |
484 | drq = dd->next_drq[WRITE]; | |
485 | else | |
486 | drq = dd->next_drq[READ]; | |
1da177e4 LT |
487 | |
488 | if (drq) { | |
489 | /* we have a "next request" */ | |
490 | ||
491 | if (dd->last_sector != drq->request->sector) | |
492 | /* end the batch on a non sequential request */ | |
493 | dd->batching += dd->fifo_batch; | |
494 | ||
495 | if (dd->batching < dd->fifo_batch) | |
496 | /* we are still entitled to batch */ | |
497 | goto dispatch_request; | |
498 | } | |
499 | ||
500 | /* | |
501 | * at this point we are not running a batch. select the appropriate | |
502 | * data direction (read / write) | |
503 | */ | |
504 | ||
505 | if (reads) { | |
506 | BUG_ON(RB_EMPTY(&dd->sort_list[READ])); | |
507 | ||
508 | if (writes && (dd->starved++ >= dd->writes_starved)) | |
509 | goto dispatch_writes; | |
510 | ||
511 | data_dir = READ; | |
1da177e4 LT |
512 | |
513 | goto dispatch_find_request; | |
514 | } | |
515 | ||
516 | /* | |
517 | * there are either no reads or writes have been starved | |
518 | */ | |
519 | ||
520 | if (writes) { | |
521 | dispatch_writes: | |
522 | BUG_ON(RB_EMPTY(&dd->sort_list[WRITE])); | |
523 | ||
524 | dd->starved = 0; | |
525 | ||
526 | data_dir = WRITE; | |
1da177e4 LT |
527 | |
528 | goto dispatch_find_request; | |
529 | } | |
530 | ||
531 | return 0; | |
532 | ||
533 | dispatch_find_request: | |
534 | /* | |
535 | * we are not running a batch, find best request for selected data_dir | |
536 | */ | |
537 | if (deadline_check_fifo(dd, data_dir)) { | |
538 | /* An expired request exists - satisfy it */ | |
539 | dd->batching = 0; | |
540 | drq = list_entry_fifo(dd->fifo_list[data_dir].next); | |
541 | ||
542 | } else if (dd->next_drq[data_dir]) { | |
543 | /* | |
544 | * The last req was the same dir and we have a next request in | |
545 | * sort order. No expired requests so continue on from here. | |
546 | */ | |
547 | drq = dd->next_drq[data_dir]; | |
548 | } else { | |
549 | /* | |
550 | * The last req was the other direction or we have run out of | |
551 | * higher-sectored requests. Go back to the lowest sectored | |
552 | * request (1 way elevator) and start a new batch. | |
553 | */ | |
554 | dd->batching = 0; | |
555 | drq = deadline_find_first_drq(dd, data_dir); | |
556 | } | |
557 | ||
558 | dispatch_request: | |
559 | /* | |
560 | * drq is the selected appropriate request. | |
561 | */ | |
562 | dd->batching++; | |
563 | deadline_move_request(dd, drq); | |
564 | ||
565 | return 1; | |
566 | } | |
567 | ||
1da177e4 LT |
568 | static int deadline_queue_empty(request_queue_t *q) |
569 | { | |
570 | struct deadline_data *dd = q->elevator->elevator_data; | |
571 | ||
b4878f24 JA |
572 | return list_empty(&dd->fifo_list[WRITE]) |
573 | && list_empty(&dd->fifo_list[READ]); | |
1da177e4 LT |
574 | } |
575 | ||
576 | static struct request * | |
577 | deadline_former_request(request_queue_t *q, struct request *rq) | |
578 | { | |
579 | struct deadline_rq *drq = RQ_DATA(rq); | |
580 | struct rb_node *rbprev = rb_prev(&drq->rb_node); | |
581 | ||
582 | if (rbprev) | |
583 | return rb_entry_drq(rbprev)->request; | |
584 | ||
585 | return NULL; | |
586 | } | |
587 | ||
588 | static struct request * | |
589 | deadline_latter_request(request_queue_t *q, struct request *rq) | |
590 | { | |
591 | struct deadline_rq *drq = RQ_DATA(rq); | |
592 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
593 | ||
594 | if (rbnext) | |
595 | return rb_entry_drq(rbnext)->request; | |
596 | ||
597 | return NULL; | |
598 | } | |
599 | ||
600 | static void deadline_exit_queue(elevator_t *e) | |
601 | { | |
602 | struct deadline_data *dd = e->elevator_data; | |
603 | ||
604 | BUG_ON(!list_empty(&dd->fifo_list[READ])); | |
605 | BUG_ON(!list_empty(&dd->fifo_list[WRITE])); | |
606 | ||
607 | mempool_destroy(dd->drq_pool); | |
608 | kfree(dd->hash); | |
609 | kfree(dd); | |
610 | } | |
611 | ||
612 | /* | |
613 | * initialize elevator private data (deadline_data), and alloc a drq for | |
614 | * each request on the free lists | |
615 | */ | |
bc1c1169 | 616 | static void *deadline_init_queue(request_queue_t *q, elevator_t *e) |
1da177e4 LT |
617 | { |
618 | struct deadline_data *dd; | |
619 | int i; | |
620 | ||
621 | if (!drq_pool) | |
bc1c1169 | 622 | return NULL; |
1da177e4 | 623 | |
1946089a | 624 | dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node); |
1da177e4 | 625 | if (!dd) |
bc1c1169 | 626 | return NULL; |
1da177e4 LT |
627 | memset(dd, 0, sizeof(*dd)); |
628 | ||
1946089a CL |
629 | dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES, |
630 | GFP_KERNEL, q->node); | |
1da177e4 LT |
631 | if (!dd->hash) { |
632 | kfree(dd); | |
bc1c1169 | 633 | return NULL; |
1da177e4 LT |
634 | } |
635 | ||
1946089a CL |
636 | dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
637 | mempool_free_slab, drq_pool, q->node); | |
1da177e4 LT |
638 | if (!dd->drq_pool) { |
639 | kfree(dd->hash); | |
640 | kfree(dd); | |
bc1c1169 | 641 | return NULL; |
1da177e4 LT |
642 | } |
643 | ||
644 | for (i = 0; i < DL_HASH_ENTRIES; i++) | |
645 | INIT_LIST_HEAD(&dd->hash[i]); | |
646 | ||
647 | INIT_LIST_HEAD(&dd->fifo_list[READ]); | |
648 | INIT_LIST_HEAD(&dd->fifo_list[WRITE]); | |
649 | dd->sort_list[READ] = RB_ROOT; | |
650 | dd->sort_list[WRITE] = RB_ROOT; | |
1da177e4 LT |
651 | dd->fifo_expire[READ] = read_expire; |
652 | dd->fifo_expire[WRITE] = write_expire; | |
653 | dd->writes_starved = writes_starved; | |
654 | dd->front_merges = 1; | |
655 | dd->fifo_batch = fifo_batch; | |
bc1c1169 | 656 | return dd; |
1da177e4 LT |
657 | } |
658 | ||
659 | static void deadline_put_request(request_queue_t *q, struct request *rq) | |
660 | { | |
661 | struct deadline_data *dd = q->elevator->elevator_data; | |
662 | struct deadline_rq *drq = RQ_DATA(rq); | |
663 | ||
b4878f24 JA |
664 | mempool_free(drq, dd->drq_pool); |
665 | rq->elevator_private = NULL; | |
1da177e4 LT |
666 | } |
667 | ||
668 | static int | |
22e2c507 | 669 | deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 670 | gfp_t gfp_mask) |
1da177e4 LT |
671 | { |
672 | struct deadline_data *dd = q->elevator->elevator_data; | |
673 | struct deadline_rq *drq; | |
674 | ||
675 | drq = mempool_alloc(dd->drq_pool, gfp_mask); | |
676 | if (drq) { | |
677 | memset(drq, 0, sizeof(*drq)); | |
678 | RB_CLEAR(&drq->rb_node); | |
679 | drq->request = rq; | |
680 | ||
681 | INIT_LIST_HEAD(&drq->hash); | |
682 | drq->on_hash = 0; | |
683 | ||
684 | INIT_LIST_HEAD(&drq->fifo); | |
685 | ||
686 | rq->elevator_private = drq; | |
687 | return 0; | |
688 | } | |
689 | ||
690 | return 1; | |
691 | } | |
692 | ||
693 | /* | |
694 | * sysfs parts below | |
695 | */ | |
1da177e4 LT |
696 | |
697 | static ssize_t | |
698 | deadline_var_show(int var, char *page) | |
699 | { | |
700 | return sprintf(page, "%d\n", var); | |
701 | } | |
702 | ||
703 | static ssize_t | |
704 | deadline_var_store(int *var, const char *page, size_t count) | |
705 | { | |
706 | char *p = (char *) page; | |
707 | ||
708 | *var = simple_strtol(p, &p, 10); | |
709 | return count; | |
710 | } | |
711 | ||
712 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
3d1ab40f | 713 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 714 | { \ |
3d1ab40f AV |
715 | struct deadline_data *dd = e->elevator_data; \ |
716 | int __data = __VAR; \ | |
1da177e4 LT |
717 | if (__CONV) \ |
718 | __data = jiffies_to_msecs(__data); \ | |
719 | return deadline_var_show(__data, (page)); \ | |
720 | } | |
e572ec7e AV |
721 | SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1); |
722 | SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1); | |
723 | SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0); | |
724 | SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0); | |
725 | SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0); | |
1da177e4 LT |
726 | #undef SHOW_FUNCTION |
727 | ||
728 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 729 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 730 | { \ |
3d1ab40f | 731 | struct deadline_data *dd = e->elevator_data; \ |
1da177e4 LT |
732 | int __data; \ |
733 | int ret = deadline_var_store(&__data, (page), count); \ | |
734 | if (__data < (MIN)) \ | |
735 | __data = (MIN); \ | |
736 | else if (__data > (MAX)) \ | |
737 | __data = (MAX); \ | |
738 | if (__CONV) \ | |
739 | *(__PTR) = msecs_to_jiffies(__data); \ | |
740 | else \ | |
741 | *(__PTR) = __data; \ | |
742 | return ret; \ | |
743 | } | |
e572ec7e AV |
744 | STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); |
745 | STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); | |
746 | STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); | |
747 | STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0); | |
748 | STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0); | |
1da177e4 LT |
749 | #undef STORE_FUNCTION |
750 | ||
e572ec7e AV |
751 | #define DD_ATTR(name) \ |
752 | __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \ | |
753 | deadline_##name##_store) | |
754 | ||
755 | static struct elv_fs_entry deadline_attrs[] = { | |
756 | DD_ATTR(read_expire), | |
757 | DD_ATTR(write_expire), | |
758 | DD_ATTR(writes_starved), | |
759 | DD_ATTR(front_merges), | |
760 | DD_ATTR(fifo_batch), | |
761 | __ATTR_NULL | |
1da177e4 LT |
762 | }; |
763 | ||
1da177e4 LT |
764 | static struct elevator_type iosched_deadline = { |
765 | .ops = { | |
766 | .elevator_merge_fn = deadline_merge, | |
767 | .elevator_merged_fn = deadline_merged_request, | |
768 | .elevator_merge_req_fn = deadline_merged_requests, | |
b4878f24 JA |
769 | .elevator_dispatch_fn = deadline_dispatch_requests, |
770 | .elevator_add_req_fn = deadline_add_request, | |
1da177e4 LT |
771 | .elevator_queue_empty_fn = deadline_queue_empty, |
772 | .elevator_former_req_fn = deadline_former_request, | |
773 | .elevator_latter_req_fn = deadline_latter_request, | |
774 | .elevator_set_req_fn = deadline_set_request, | |
775 | .elevator_put_req_fn = deadline_put_request, | |
776 | .elevator_init_fn = deadline_init_queue, | |
777 | .elevator_exit_fn = deadline_exit_queue, | |
778 | }, | |
779 | ||
3d1ab40f | 780 | .elevator_attrs = deadline_attrs, |
1da177e4 LT |
781 | .elevator_name = "deadline", |
782 | .elevator_owner = THIS_MODULE, | |
783 | }; | |
784 | ||
785 | static int __init deadline_init(void) | |
786 | { | |
787 | int ret; | |
788 | ||
789 | drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq), | |
790 | 0, 0, NULL, NULL); | |
791 | ||
792 | if (!drq_pool) | |
793 | return -ENOMEM; | |
794 | ||
795 | ret = elv_register(&iosched_deadline); | |
796 | if (ret) | |
797 | kmem_cache_destroy(drq_pool); | |
798 | ||
799 | return ret; | |
800 | } | |
801 | ||
802 | static void __exit deadline_exit(void) | |
803 | { | |
804 | kmem_cache_destroy(drq_pool); | |
805 | elv_unregister(&iosched_deadline); | |
806 | } | |
807 | ||
808 | module_init(deadline_init); | |
809 | module_exit(deadline_exit); | |
810 | ||
811 | MODULE_AUTHOR("Jens Axboe"); | |
812 | MODULE_LICENSE("GPL"); | |
813 | MODULE_DESCRIPTION("deadline IO scheduler"); |