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> | |
1da177e4 LT |
11 | #include <linux/module.h> |
12 | #include <linux/slab.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/compiler.h> | |
15 | #include <linux/hash.h> | |
16 | #include <linux/rbtree.h> | |
17 | ||
18 | /* | |
19 | * See Documentation/block/deadline-iosched.txt | |
20 | */ | |
64100099 AV |
21 | static const int read_expire = HZ / 2; /* max time before a read is submitted. */ |
22 | static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ | |
23 | static const int writes_starved = 2; /* max times reads can starve a write */ | |
24 | static const int fifo_batch = 16; /* # of sequential requests treated as one | |
1da177e4 LT |
25 | by the above parameters. For throughput. */ |
26 | ||
27 | static const int deadline_hash_shift = 5; | |
28 | #define DL_HASH_BLOCK(sec) ((sec) >> 3) | |
29 | #define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift)) | |
30 | #define DL_HASH_ENTRIES (1 << deadline_hash_shift) | |
31 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
bae386f7 | 32 | #define ON_HASH(drq) (!hlist_unhashed(&(drq)->hash)) |
1da177e4 LT |
33 | |
34 | struct deadline_data { | |
35 | /* | |
36 | * run time data | |
37 | */ | |
38 | ||
39 | /* | |
40 | * requests (deadline_rq s) are present on both sort_list and fifo_list | |
41 | */ | |
42 | struct rb_root sort_list[2]; | |
43 | struct list_head fifo_list[2]; | |
44 | ||
45 | /* | |
46 | * next in sort order. read, write or both are NULL | |
47 | */ | |
48 | struct deadline_rq *next_drq[2]; | |
bae386f7 | 49 | struct hlist_head *hash; /* request hash */ |
1da177e4 LT |
50 | unsigned int batching; /* number of sequential requests made */ |
51 | sector_t last_sector; /* head position */ | |
52 | unsigned int starved; /* times reads have starved writes */ | |
53 | ||
54 | /* | |
55 | * settings that change how the i/o scheduler behaves | |
56 | */ | |
57 | int fifo_expire[2]; | |
58 | int fifo_batch; | |
59 | int writes_starved; | |
60 | int front_merges; | |
61 | ||
62 | mempool_t *drq_pool; | |
63 | }; | |
64 | ||
65 | /* | |
66 | * pre-request data. | |
67 | */ | |
68 | struct deadline_rq { | |
69 | /* | |
70 | * rbtree index, key is the starting offset | |
71 | */ | |
72 | struct rb_node rb_node; | |
73 | sector_t rb_key; | |
74 | ||
75 | struct request *request; | |
76 | ||
77 | /* | |
78 | * request hash, key is the ending offset (for back merge lookup) | |
79 | */ | |
bae386f7 | 80 | struct hlist_node hash; |
1da177e4 LT |
81 | |
82 | /* | |
83 | * expire fifo | |
84 | */ | |
85 | struct list_head fifo; | |
86 | unsigned long expires; | |
87 | }; | |
88 | ||
89 | static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq); | |
90 | ||
91 | static kmem_cache_t *drq_pool; | |
92 | ||
93 | #define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private) | |
94 | ||
95 | /* | |
96 | * the back merge hash support functions | |
97 | */ | |
98 | static inline void __deadline_del_drq_hash(struct deadline_rq *drq) | |
99 | { | |
bae386f7 | 100 | hlist_del_init(&drq->hash); |
1da177e4 LT |
101 | } |
102 | ||
103 | static inline void deadline_del_drq_hash(struct deadline_rq *drq) | |
104 | { | |
105 | if (ON_HASH(drq)) | |
106 | __deadline_del_drq_hash(drq); | |
107 | } | |
108 | ||
1da177e4 LT |
109 | static inline void |
110 | deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
111 | { | |
112 | struct request *rq = drq->request; | |
113 | ||
114 | BUG_ON(ON_HASH(drq)); | |
115 | ||
bae386f7 | 116 | hlist_add_head(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]); |
1da177e4 LT |
117 | } |
118 | ||
119 | /* | |
120 | * move hot entry to front of chain | |
121 | */ | |
122 | static inline void | |
123 | deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq) | |
124 | { | |
125 | struct request *rq = drq->request; | |
bae386f7 | 126 | struct hlist_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))]; |
1da177e4 | 127 | |
bae386f7 AM |
128 | if (ON_HASH(drq) && &drq->hash != head->first) { |
129 | hlist_del(&drq->hash); | |
130 | hlist_add_head(&drq->hash, head); | |
1da177e4 LT |
131 | } |
132 | } | |
133 | ||
134 | static struct request * | |
135 | deadline_find_drq_hash(struct deadline_data *dd, sector_t offset) | |
136 | { | |
bae386f7 AM |
137 | struct hlist_head *hash_list = &dd->hash[DL_HASH_FN(offset)]; |
138 | struct hlist_node *entry, *next; | |
139 | struct deadline_rq *drq; | |
1da177e4 | 140 | |
bae386f7 | 141 | hlist_for_each_entry_safe(drq, entry, next, hash_list, hash) { |
1da177e4 LT |
142 | struct request *__rq = drq->request; |
143 | ||
1da177e4 LT |
144 | BUG_ON(!ON_HASH(drq)); |
145 | ||
146 | if (!rq_mergeable(__rq)) { | |
147 | __deadline_del_drq_hash(drq); | |
148 | continue; | |
149 | } | |
150 | ||
151 | if (rq_hash_key(__rq) == offset) | |
152 | return __rq; | |
153 | } | |
154 | ||
155 | return NULL; | |
156 | } | |
157 | ||
158 | /* | |
159 | * rb tree support functions | |
160 | */ | |
1da177e4 LT |
161 | #define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node) |
162 | #define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)]) | |
163 | #define rq_rb_key(rq) (rq)->sector | |
164 | ||
165 | static struct deadline_rq * | |
166 | __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
167 | { | |
168 | struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node; | |
169 | struct rb_node *parent = NULL; | |
170 | struct deadline_rq *__drq; | |
171 | ||
172 | while (*p) { | |
173 | parent = *p; | |
174 | __drq = rb_entry_drq(parent); | |
175 | ||
176 | if (drq->rb_key < __drq->rb_key) | |
177 | p = &(*p)->rb_left; | |
178 | else if (drq->rb_key > __drq->rb_key) | |
179 | p = &(*p)->rb_right; | |
180 | else | |
181 | return __drq; | |
182 | } | |
183 | ||
184 | rb_link_node(&drq->rb_node, parent, p); | |
185 | return NULL; | |
186 | } | |
187 | ||
188 | static void | |
189 | deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
190 | { | |
191 | struct deadline_rq *__alias; | |
192 | ||
193 | drq->rb_key = rq_rb_key(drq->request); | |
194 | ||
195 | retry: | |
196 | __alias = __deadline_add_drq_rb(dd, drq); | |
197 | if (!__alias) { | |
198 | rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); | |
199 | return; | |
200 | } | |
201 | ||
202 | deadline_move_request(dd, __alias); | |
203 | goto retry; | |
204 | } | |
205 | ||
206 | static inline void | |
207 | deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq) | |
208 | { | |
209 | const int data_dir = rq_data_dir(drq->request); | |
210 | ||
211 | if (dd->next_drq[data_dir] == drq) { | |
212 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
213 | ||
214 | dd->next_drq[data_dir] = NULL; | |
215 | if (rbnext) | |
216 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
217 | } | |
218 | ||
dd67d051 | 219 | BUG_ON(!RB_EMPTY_NODE(&drq->rb_node)); |
b4878f24 | 220 | rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq)); |
dd67d051 | 221 | RB_CLEAR_NODE(&drq->rb_node); |
1da177e4 LT |
222 | } |
223 | ||
224 | static struct request * | |
225 | deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir) | |
226 | { | |
227 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
228 | struct deadline_rq *drq; | |
229 | ||
230 | while (n) { | |
231 | drq = rb_entry_drq(n); | |
232 | ||
233 | if (sector < drq->rb_key) | |
234 | n = n->rb_left; | |
235 | else if (sector > drq->rb_key) | |
236 | n = n->rb_right; | |
237 | else | |
238 | return drq->request; | |
239 | } | |
240 | ||
241 | return NULL; | |
242 | } | |
243 | ||
244 | /* | |
245 | * deadline_find_first_drq finds the first (lowest sector numbered) request | |
246 | * for the specified data_dir. Used to sweep back to the start of the disk | |
247 | * (1-way elevator) after we process the last (highest sector) request. | |
248 | */ | |
249 | static struct deadline_rq * | |
250 | deadline_find_first_drq(struct deadline_data *dd, int data_dir) | |
251 | { | |
252 | struct rb_node *n = dd->sort_list[data_dir].rb_node; | |
253 | ||
254 | for (;;) { | |
255 | if (n->rb_left == NULL) | |
256 | return rb_entry_drq(n); | |
257 | ||
258 | n = n->rb_left; | |
259 | } | |
260 | } | |
261 | ||
262 | /* | |
263 | * add drq to rbtree and fifo | |
264 | */ | |
b4878f24 | 265 | static void |
1da177e4 LT |
266 | deadline_add_request(struct request_queue *q, struct request *rq) |
267 | { | |
268 | struct deadline_data *dd = q->elevator->elevator_data; | |
269 | struct deadline_rq *drq = RQ_DATA(rq); | |
270 | ||
271 | const int data_dir = rq_data_dir(drq->request); | |
272 | ||
273 | deadline_add_drq_rb(dd, drq); | |
274 | /* | |
275 | * set expire time (only used for reads) and add to fifo list | |
276 | */ | |
277 | drq->expires = jiffies + dd->fifo_expire[data_dir]; | |
278 | list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]); | |
279 | ||
98b11471 | 280 | if (rq_mergeable(rq)) |
1da177e4 | 281 | deadline_add_drq_hash(dd, drq); |
1da177e4 LT |
282 | } |
283 | ||
284 | /* | |
285 | * remove rq from rbtree, fifo, and hash | |
286 | */ | |
287 | static void deadline_remove_request(request_queue_t *q, struct request *rq) | |
288 | { | |
289 | struct deadline_rq *drq = RQ_DATA(rq); | |
b4878f24 | 290 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 | 291 | |
b4878f24 | 292 | list_del_init(&drq->fifo); |
b4878f24 | 293 | deadline_del_drq_rb(dd, drq); |
98b11471 | 294 | deadline_del_drq_hash(drq); |
1da177e4 LT |
295 | } |
296 | ||
297 | static int | |
298 | deadline_merge(request_queue_t *q, struct request **req, struct bio *bio) | |
299 | { | |
300 | struct deadline_data *dd = q->elevator->elevator_data; | |
301 | struct request *__rq; | |
302 | int ret; | |
303 | ||
1da177e4 LT |
304 | /* |
305 | * see if the merge hash can satisfy a back merge | |
306 | */ | |
307 | __rq = deadline_find_drq_hash(dd, bio->bi_sector); | |
308 | if (__rq) { | |
309 | BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); | |
310 | ||
311 | if (elv_rq_merge_ok(__rq, bio)) { | |
312 | ret = ELEVATOR_BACK_MERGE; | |
313 | goto out; | |
314 | } | |
315 | } | |
316 | ||
317 | /* | |
318 | * check for front merge | |
319 | */ | |
320 | if (dd->front_merges) { | |
321 | sector_t rb_key = bio->bi_sector + bio_sectors(bio); | |
322 | ||
323 | __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio)); | |
324 | if (__rq) { | |
325 | BUG_ON(rb_key != rq_rb_key(__rq)); | |
326 | ||
327 | if (elv_rq_merge_ok(__rq, bio)) { | |
328 | ret = ELEVATOR_FRONT_MERGE; | |
329 | goto out; | |
330 | } | |
331 | } | |
332 | } | |
333 | ||
334 | return ELEVATOR_NO_MERGE; | |
335 | out: | |
1da177e4 LT |
336 | if (ret) |
337 | deadline_hot_drq_hash(dd, RQ_DATA(__rq)); | |
338 | *req = __rq; | |
339 | return ret; | |
340 | } | |
341 | ||
342 | static void deadline_merged_request(request_queue_t *q, struct request *req) | |
343 | { | |
344 | struct deadline_data *dd = q->elevator->elevator_data; | |
345 | struct deadline_rq *drq = RQ_DATA(req); | |
346 | ||
347 | /* | |
348 | * hash always needs to be repositioned, key is end sector | |
349 | */ | |
350 | deadline_del_drq_hash(drq); | |
351 | deadline_add_drq_hash(dd, drq); | |
352 | ||
353 | /* | |
354 | * if the merge was a front merge, we need to reposition request | |
355 | */ | |
356 | if (rq_rb_key(req) != drq->rb_key) { | |
357 | deadline_del_drq_rb(dd, drq); | |
358 | deadline_add_drq_rb(dd, drq); | |
359 | } | |
1da177e4 LT |
360 | } |
361 | ||
362 | static void | |
363 | deadline_merged_requests(request_queue_t *q, struct request *req, | |
364 | struct request *next) | |
365 | { | |
366 | struct deadline_data *dd = q->elevator->elevator_data; | |
367 | struct deadline_rq *drq = RQ_DATA(req); | |
368 | struct deadline_rq *dnext = RQ_DATA(next); | |
369 | ||
370 | BUG_ON(!drq); | |
371 | BUG_ON(!dnext); | |
372 | ||
373 | /* | |
374 | * reposition drq (this is the merged request) in hash, and in rbtree | |
375 | * in case of a front merge | |
376 | */ | |
377 | deadline_del_drq_hash(drq); | |
378 | deadline_add_drq_hash(dd, drq); | |
379 | ||
380 | if (rq_rb_key(req) != drq->rb_key) { | |
381 | deadline_del_drq_rb(dd, drq); | |
382 | deadline_add_drq_rb(dd, drq); | |
383 | } | |
384 | ||
385 | /* | |
386 | * if dnext expires before drq, assign its expire time to drq | |
387 | * and move into dnext position (dnext will be deleted) in fifo | |
388 | */ | |
389 | if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) { | |
390 | if (time_before(dnext->expires, drq->expires)) { | |
391 | list_move(&drq->fifo, &dnext->fifo); | |
392 | drq->expires = dnext->expires; | |
393 | } | |
394 | } | |
395 | ||
396 | /* | |
397 | * kill knowledge of next, this one is a goner | |
398 | */ | |
399 | deadline_remove_request(q, next); | |
400 | } | |
401 | ||
402 | /* | |
403 | * move request from sort list to dispatch queue. | |
404 | */ | |
405 | static inline void | |
406 | deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq) | |
407 | { | |
408 | request_queue_t *q = drq->request->q; | |
409 | ||
410 | deadline_remove_request(q, drq->request); | |
b4878f24 | 411 | elv_dispatch_add_tail(q, drq->request); |
1da177e4 LT |
412 | } |
413 | ||
414 | /* | |
415 | * move an entry to dispatch queue | |
416 | */ | |
417 | static void | |
418 | deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq) | |
419 | { | |
420 | const int data_dir = rq_data_dir(drq->request); | |
421 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
422 | ||
423 | dd->next_drq[READ] = NULL; | |
424 | dd->next_drq[WRITE] = NULL; | |
425 | ||
426 | if (rbnext) | |
427 | dd->next_drq[data_dir] = rb_entry_drq(rbnext); | |
428 | ||
429 | dd->last_sector = drq->request->sector + drq->request->nr_sectors; | |
430 | ||
431 | /* | |
432 | * take it off the sort and fifo list, move | |
433 | * to dispatch queue | |
434 | */ | |
435 | deadline_move_to_dispatch(dd, drq); | |
436 | } | |
437 | ||
438 | #define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo) | |
439 | ||
440 | /* | |
441 | * deadline_check_fifo returns 0 if there are no expired reads on the fifo, | |
442 | * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) | |
443 | */ | |
444 | static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) | |
445 | { | |
446 | struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next); | |
447 | ||
448 | /* | |
449 | * drq is expired! | |
450 | */ | |
451 | if (time_after(jiffies, drq->expires)) | |
452 | return 1; | |
453 | ||
454 | return 0; | |
455 | } | |
456 | ||
457 | /* | |
458 | * deadline_dispatch_requests selects the best request according to | |
459 | * read/write expire, fifo_batch, etc | |
460 | */ | |
b4878f24 | 461 | static int deadline_dispatch_requests(request_queue_t *q, int force) |
1da177e4 | 462 | { |
b4878f24 | 463 | struct deadline_data *dd = q->elevator->elevator_data; |
1da177e4 LT |
464 | const int reads = !list_empty(&dd->fifo_list[READ]); |
465 | const int writes = !list_empty(&dd->fifo_list[WRITE]); | |
466 | struct deadline_rq *drq; | |
4b0dc07e | 467 | int data_dir; |
1da177e4 LT |
468 | |
469 | /* | |
470 | * batches are currently reads XOR writes | |
471 | */ | |
9d5c1e1b AM |
472 | if (dd->next_drq[WRITE]) |
473 | drq = dd->next_drq[WRITE]; | |
474 | else | |
475 | drq = dd->next_drq[READ]; | |
1da177e4 LT |
476 | |
477 | if (drq) { | |
478 | /* we have a "next request" */ | |
479 | ||
480 | if (dd->last_sector != drq->request->sector) | |
481 | /* end the batch on a non sequential request */ | |
482 | dd->batching += dd->fifo_batch; | |
483 | ||
484 | if (dd->batching < dd->fifo_batch) | |
485 | /* we are still entitled to batch */ | |
486 | goto dispatch_request; | |
487 | } | |
488 | ||
489 | /* | |
490 | * at this point we are not running a batch. select the appropriate | |
491 | * data direction (read / write) | |
492 | */ | |
493 | ||
494 | if (reads) { | |
dd67d051 | 495 | BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ])); |
1da177e4 LT |
496 | |
497 | if (writes && (dd->starved++ >= dd->writes_starved)) | |
498 | goto dispatch_writes; | |
499 | ||
500 | data_dir = READ; | |
1da177e4 LT |
501 | |
502 | goto dispatch_find_request; | |
503 | } | |
504 | ||
505 | /* | |
506 | * there are either no reads or writes have been starved | |
507 | */ | |
508 | ||
509 | if (writes) { | |
510 | dispatch_writes: | |
dd67d051 | 511 | BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE])); |
1da177e4 LT |
512 | |
513 | dd->starved = 0; | |
514 | ||
515 | data_dir = WRITE; | |
1da177e4 LT |
516 | |
517 | goto dispatch_find_request; | |
518 | } | |
519 | ||
520 | return 0; | |
521 | ||
522 | dispatch_find_request: | |
523 | /* | |
524 | * we are not running a batch, find best request for selected data_dir | |
525 | */ | |
526 | if (deadline_check_fifo(dd, data_dir)) { | |
527 | /* An expired request exists - satisfy it */ | |
528 | dd->batching = 0; | |
529 | drq = list_entry_fifo(dd->fifo_list[data_dir].next); | |
530 | ||
531 | } else if (dd->next_drq[data_dir]) { | |
532 | /* | |
533 | * The last req was the same dir and we have a next request in | |
534 | * sort order. No expired requests so continue on from here. | |
535 | */ | |
536 | drq = dd->next_drq[data_dir]; | |
537 | } else { | |
538 | /* | |
539 | * The last req was the other direction or we have run out of | |
540 | * higher-sectored requests. Go back to the lowest sectored | |
541 | * request (1 way elevator) and start a new batch. | |
542 | */ | |
543 | dd->batching = 0; | |
544 | drq = deadline_find_first_drq(dd, data_dir); | |
545 | } | |
546 | ||
547 | dispatch_request: | |
548 | /* | |
549 | * drq is the selected appropriate request. | |
550 | */ | |
551 | dd->batching++; | |
552 | deadline_move_request(dd, drq); | |
553 | ||
554 | return 1; | |
555 | } | |
556 | ||
1da177e4 LT |
557 | static int deadline_queue_empty(request_queue_t *q) |
558 | { | |
559 | struct deadline_data *dd = q->elevator->elevator_data; | |
560 | ||
b4878f24 JA |
561 | return list_empty(&dd->fifo_list[WRITE]) |
562 | && list_empty(&dd->fifo_list[READ]); | |
1da177e4 LT |
563 | } |
564 | ||
565 | static struct request * | |
566 | deadline_former_request(request_queue_t *q, struct request *rq) | |
567 | { | |
568 | struct deadline_rq *drq = RQ_DATA(rq); | |
569 | struct rb_node *rbprev = rb_prev(&drq->rb_node); | |
570 | ||
571 | if (rbprev) | |
572 | return rb_entry_drq(rbprev)->request; | |
573 | ||
574 | return NULL; | |
575 | } | |
576 | ||
577 | static struct request * | |
578 | deadline_latter_request(request_queue_t *q, struct request *rq) | |
579 | { | |
580 | struct deadline_rq *drq = RQ_DATA(rq); | |
581 | struct rb_node *rbnext = rb_next(&drq->rb_node); | |
582 | ||
583 | if (rbnext) | |
584 | return rb_entry_drq(rbnext)->request; | |
585 | ||
586 | return NULL; | |
587 | } | |
588 | ||
589 | static void deadline_exit_queue(elevator_t *e) | |
590 | { | |
591 | struct deadline_data *dd = e->elevator_data; | |
592 | ||
593 | BUG_ON(!list_empty(&dd->fifo_list[READ])); | |
594 | BUG_ON(!list_empty(&dd->fifo_list[WRITE])); | |
595 | ||
596 | mempool_destroy(dd->drq_pool); | |
597 | kfree(dd->hash); | |
598 | kfree(dd); | |
599 | } | |
600 | ||
601 | /* | |
602 | * initialize elevator private data (deadline_data), and alloc a drq for | |
603 | * each request on the free lists | |
604 | */ | |
bc1c1169 | 605 | static void *deadline_init_queue(request_queue_t *q, elevator_t *e) |
1da177e4 LT |
606 | { |
607 | struct deadline_data *dd; | |
608 | int i; | |
609 | ||
610 | if (!drq_pool) | |
bc1c1169 | 611 | return NULL; |
1da177e4 | 612 | |
1946089a | 613 | dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node); |
1da177e4 | 614 | if (!dd) |
bc1c1169 | 615 | return NULL; |
1da177e4 LT |
616 | memset(dd, 0, sizeof(*dd)); |
617 | ||
bae386f7 | 618 | dd->hash = kmalloc_node(sizeof(struct hlist_head)*DL_HASH_ENTRIES, |
1946089a | 619 | GFP_KERNEL, q->node); |
1da177e4 LT |
620 | if (!dd->hash) { |
621 | kfree(dd); | |
bc1c1169 | 622 | return NULL; |
1da177e4 LT |
623 | } |
624 | ||
1946089a CL |
625 | dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
626 | mempool_free_slab, drq_pool, q->node); | |
1da177e4 LT |
627 | if (!dd->drq_pool) { |
628 | kfree(dd->hash); | |
629 | kfree(dd); | |
bc1c1169 | 630 | return NULL; |
1da177e4 LT |
631 | } |
632 | ||
633 | for (i = 0; i < DL_HASH_ENTRIES; i++) | |
bae386f7 | 634 | INIT_HLIST_HEAD(&dd->hash[i]); |
1da177e4 LT |
635 | |
636 | INIT_LIST_HEAD(&dd->fifo_list[READ]); | |
637 | INIT_LIST_HEAD(&dd->fifo_list[WRITE]); | |
638 | dd->sort_list[READ] = RB_ROOT; | |
639 | dd->sort_list[WRITE] = RB_ROOT; | |
1da177e4 LT |
640 | dd->fifo_expire[READ] = read_expire; |
641 | dd->fifo_expire[WRITE] = write_expire; | |
642 | dd->writes_starved = writes_starved; | |
643 | dd->front_merges = 1; | |
644 | dd->fifo_batch = fifo_batch; | |
bc1c1169 | 645 | return dd; |
1da177e4 LT |
646 | } |
647 | ||
648 | static void deadline_put_request(request_queue_t *q, struct request *rq) | |
649 | { | |
650 | struct deadline_data *dd = q->elevator->elevator_data; | |
651 | struct deadline_rq *drq = RQ_DATA(rq); | |
652 | ||
b4878f24 JA |
653 | mempool_free(drq, dd->drq_pool); |
654 | rq->elevator_private = NULL; | |
1da177e4 LT |
655 | } |
656 | ||
657 | static int | |
22e2c507 | 658 | deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 659 | gfp_t gfp_mask) |
1da177e4 LT |
660 | { |
661 | struct deadline_data *dd = q->elevator->elevator_data; | |
662 | struct deadline_rq *drq; | |
663 | ||
664 | drq = mempool_alloc(dd->drq_pool, gfp_mask); | |
665 | if (drq) { | |
666 | memset(drq, 0, sizeof(*drq)); | |
dd67d051 | 667 | RB_CLEAR_NODE(&drq->rb_node); |
1da177e4 LT |
668 | drq->request = rq; |
669 | ||
bae386f7 | 670 | INIT_HLIST_NODE(&drq->hash); |
1da177e4 LT |
671 | |
672 | INIT_LIST_HEAD(&drq->fifo); | |
673 | ||
674 | rq->elevator_private = drq; | |
675 | return 0; | |
676 | } | |
677 | ||
678 | return 1; | |
679 | } | |
680 | ||
681 | /* | |
682 | * sysfs parts below | |
683 | */ | |
1da177e4 LT |
684 | |
685 | static ssize_t | |
686 | deadline_var_show(int var, char *page) | |
687 | { | |
688 | return sprintf(page, "%d\n", var); | |
689 | } | |
690 | ||
691 | static ssize_t | |
692 | deadline_var_store(int *var, const char *page, size_t count) | |
693 | { | |
694 | char *p = (char *) page; | |
695 | ||
696 | *var = simple_strtol(p, &p, 10); | |
697 | return count; | |
698 | } | |
699 | ||
700 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
3d1ab40f | 701 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
1da177e4 | 702 | { \ |
3d1ab40f AV |
703 | struct deadline_data *dd = e->elevator_data; \ |
704 | int __data = __VAR; \ | |
1da177e4 LT |
705 | if (__CONV) \ |
706 | __data = jiffies_to_msecs(__data); \ | |
707 | return deadline_var_show(__data, (page)); \ | |
708 | } | |
e572ec7e AV |
709 | SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1); |
710 | SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1); | |
711 | SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0); | |
712 | SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0); | |
713 | SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0); | |
1da177e4 LT |
714 | #undef SHOW_FUNCTION |
715 | ||
716 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
3d1ab40f | 717 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
1da177e4 | 718 | { \ |
3d1ab40f | 719 | struct deadline_data *dd = e->elevator_data; \ |
1da177e4 LT |
720 | int __data; \ |
721 | int ret = deadline_var_store(&__data, (page), count); \ | |
722 | if (__data < (MIN)) \ | |
723 | __data = (MIN); \ | |
724 | else if (__data > (MAX)) \ | |
725 | __data = (MAX); \ | |
726 | if (__CONV) \ | |
727 | *(__PTR) = msecs_to_jiffies(__data); \ | |
728 | else \ | |
729 | *(__PTR) = __data; \ | |
730 | return ret; \ | |
731 | } | |
e572ec7e AV |
732 | STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); |
733 | STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); | |
734 | STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); | |
735 | STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0); | |
736 | STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0); | |
1da177e4 LT |
737 | #undef STORE_FUNCTION |
738 | ||
e572ec7e AV |
739 | #define DD_ATTR(name) \ |
740 | __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \ | |
741 | deadline_##name##_store) | |
742 | ||
743 | static struct elv_fs_entry deadline_attrs[] = { | |
744 | DD_ATTR(read_expire), | |
745 | DD_ATTR(write_expire), | |
746 | DD_ATTR(writes_starved), | |
747 | DD_ATTR(front_merges), | |
748 | DD_ATTR(fifo_batch), | |
749 | __ATTR_NULL | |
1da177e4 LT |
750 | }; |
751 | ||
1da177e4 LT |
752 | static struct elevator_type iosched_deadline = { |
753 | .ops = { | |
754 | .elevator_merge_fn = deadline_merge, | |
755 | .elevator_merged_fn = deadline_merged_request, | |
756 | .elevator_merge_req_fn = deadline_merged_requests, | |
b4878f24 JA |
757 | .elevator_dispatch_fn = deadline_dispatch_requests, |
758 | .elevator_add_req_fn = deadline_add_request, | |
1da177e4 LT |
759 | .elevator_queue_empty_fn = deadline_queue_empty, |
760 | .elevator_former_req_fn = deadline_former_request, | |
761 | .elevator_latter_req_fn = deadline_latter_request, | |
762 | .elevator_set_req_fn = deadline_set_request, | |
763 | .elevator_put_req_fn = deadline_put_request, | |
764 | .elevator_init_fn = deadline_init_queue, | |
765 | .elevator_exit_fn = deadline_exit_queue, | |
766 | }, | |
767 | ||
3d1ab40f | 768 | .elevator_attrs = deadline_attrs, |
1da177e4 LT |
769 | .elevator_name = "deadline", |
770 | .elevator_owner = THIS_MODULE, | |
771 | }; | |
772 | ||
773 | static int __init deadline_init(void) | |
774 | { | |
775 | int ret; | |
776 | ||
777 | drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq), | |
778 | 0, 0, NULL, NULL); | |
779 | ||
780 | if (!drq_pool) | |
781 | return -ENOMEM; | |
782 | ||
783 | ret = elv_register(&iosched_deadline); | |
784 | if (ret) | |
785 | kmem_cache_destroy(drq_pool); | |
786 | ||
787 | return ret; | |
788 | } | |
789 | ||
790 | static void __exit deadline_exit(void) | |
791 | { | |
792 | kmem_cache_destroy(drq_pool); | |
793 | elv_unregister(&iosched_deadline); | |
794 | } | |
795 | ||
796 | module_init(deadline_init); | |
797 | module_exit(deadline_exit); | |
798 | ||
799 | MODULE_AUTHOR("Jens Axboe"); | |
800 | MODULE_LICENSE("GPL"); | |
801 | MODULE_DESCRIPTION("deadline IO scheduler"); |