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-rw-r--r--block/deadline-iosched.c878
1 files changed, 878 insertions, 0 deletions
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
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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 */
24static int read_expire = HZ / 2; /* max time before a read is submitted. */
25static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
26static int writes_starved = 2; /* max times reads can starve a write */
27static int fifo_batch = 16; /* # of sequential requests treated as one
28 by the above parameters. For throughput. */
29
30static 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
38struct 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];
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 */
72struct 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
94static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
95
96static 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 */
103static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
104{
105 drq->on_hash = 0;
106 list_del_init(&drq->hash);
107}
108
109static inline void deadline_del_drq_hash(struct deadline_rq *drq)
110{
111 if (ON_HASH(drq))
112 __deadline_del_drq_hash(drq);
113}
114
115static inline void
116deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
117{
118 struct request *rq = drq->request;
119
120 BUG_ON(ON_HASH(drq));
121
122 drq->on_hash = 1;
123 list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
124}
125
126/*
127 * move hot entry to front of chain
128 */
129static inline void
130deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
131{
132 struct request *rq = drq->request;
133 struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
134
135 if (ON_HASH(drq) && drq->hash.prev != head) {
136 list_del(&drq->hash);
137 list_add(&drq->hash, head);
138 }
139}
140
141static struct request *
142deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
143{
144 struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
145 struct list_head *entry, *next = hash_list->next;
146
147 while ((entry = next) != hash_list) {
148 struct deadline_rq *drq = list_entry_hash(entry);
149 struct request *__rq = drq->request;
150
151 next = entry->next;
152
153 BUG_ON(!ON_HASH(drq));
154
155 if (!rq_mergeable(__rq)) {
156 __deadline_del_drq_hash(drq);
157 continue;
158 }
159
160 if (rq_hash_key(__rq) == offset)
161 return __rq;
162 }
163
164 return NULL;
165}
166
167/*
168 * rb tree support functions
169 */
170#define RB_NONE (2)
171#define RB_EMPTY(root) ((root)->rb_node == NULL)
172#define ON_RB(node) ((node)->rb_color != RB_NONE)
173#define RB_CLEAR(node) ((node)->rb_color = RB_NONE)
174#define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node)
175#define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)])
176#define rq_rb_key(rq) (rq)->sector
177
178static struct deadline_rq *
179__deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
180{
181 struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
182 struct rb_node *parent = NULL;
183 struct deadline_rq *__drq;
184
185 while (*p) {
186 parent = *p;
187 __drq = rb_entry_drq(parent);
188
189 if (drq->rb_key < __drq->rb_key)
190 p = &(*p)->rb_left;
191 else if (drq->rb_key > __drq->rb_key)
192 p = &(*p)->rb_right;
193 else
194 return __drq;
195 }
196
197 rb_link_node(&drq->rb_node, parent, p);
198 return NULL;
199}
200
201static void
202deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
203{
204 struct deadline_rq *__alias;
205
206 drq->rb_key = rq_rb_key(drq->request);
207
208retry:
209 __alias = __deadline_add_drq_rb(dd, drq);
210 if (!__alias) {
211 rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
212 return;
213 }
214
215 deadline_move_request(dd, __alias);
216 goto retry;
217}
218
219static inline void
220deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
221{
222 const int data_dir = rq_data_dir(drq->request);
223
224 if (dd->next_drq[data_dir] == drq) {
225 struct rb_node *rbnext = rb_next(&drq->rb_node);
226
227 dd->next_drq[data_dir] = NULL;
228 if (rbnext)
229 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
230 }
231
232 BUG_ON(!ON_RB(&drq->rb_node));
233 rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
234 RB_CLEAR(&drq->rb_node);
235}
236
237static struct request *
238deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
239{
240 struct rb_node *n = dd->sort_list[data_dir].rb_node;
241 struct deadline_rq *drq;
242
243 while (n) {
244 drq = rb_entry_drq(n);
245
246 if (sector < drq->rb_key)
247 n = n->rb_left;
248 else if (sector > drq->rb_key)
249 n = n->rb_right;
250 else
251 return drq->request;
252 }
253
254 return NULL;
255}
256
257/*
258 * deadline_find_first_drq finds the first (lowest sector numbered) request
259 * for the specified data_dir. Used to sweep back to the start of the disk
260 * (1-way elevator) after we process the last (highest sector) request.
261 */
262static struct deadline_rq *
263deadline_find_first_drq(struct deadline_data *dd, int data_dir)
264{
265 struct rb_node *n = dd->sort_list[data_dir].rb_node;
266
267 for (;;) {
268 if (n->rb_left == NULL)
269 return rb_entry_drq(n);
270
271 n = n->rb_left;
272 }
273}
274
275/*
276 * add drq to rbtree and fifo
277 */
278static void
279deadline_add_request(struct request_queue *q, struct request *rq)
280{
281 struct deadline_data *dd = q->elevator->elevator_data;
282 struct deadline_rq *drq = RQ_DATA(rq);
283
284 const int data_dir = rq_data_dir(drq->request);
285
286 deadline_add_drq_rb(dd, drq);
287 /*
288 * set expire time (only used for reads) and add to fifo list
289 */
290 drq->expires = jiffies + dd->fifo_expire[data_dir];
291 list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
292
293 if (rq_mergeable(rq))
294 deadline_add_drq_hash(dd, drq);
295}
296
297/*
298 * remove rq from rbtree, fifo, and hash
299 */
300static void deadline_remove_request(request_queue_t *q, struct request *rq)
301{
302 struct deadline_rq *drq = RQ_DATA(rq);
303 struct deadline_data *dd = q->elevator->elevator_data;
304
305 list_del_init(&drq->fifo);
306 deadline_del_drq_rb(dd, drq);
307 deadline_del_drq_hash(drq);
308}
309
310static int
311deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
312{
313 struct deadline_data *dd = q->elevator->elevator_data;
314 struct request *__rq;
315 int ret;
316
317 /*
318 * see if the merge hash can satisfy a back merge
319 */
320 __rq = deadline_find_drq_hash(dd, bio->bi_sector);
321 if (__rq) {
322 BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
323
324 if (elv_rq_merge_ok(__rq, bio)) {
325 ret = ELEVATOR_BACK_MERGE;
326 goto out;
327 }
328 }
329
330 /*
331 * check for front merge
332 */
333 if (dd->front_merges) {
334 sector_t rb_key = bio->bi_sector + bio_sectors(bio);
335
336 __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
337 if (__rq) {
338 BUG_ON(rb_key != rq_rb_key(__rq));
339
340 if (elv_rq_merge_ok(__rq, bio)) {
341 ret = ELEVATOR_FRONT_MERGE;
342 goto out;
343 }
344 }
345 }
346
347 return ELEVATOR_NO_MERGE;
348out:
349 if (ret)
350 deadline_hot_drq_hash(dd, RQ_DATA(__rq));
351 *req = __rq;
352 return ret;
353}
354
355static void deadline_merged_request(request_queue_t *q, struct request *req)
356{
357 struct deadline_data *dd = q->elevator->elevator_data;
358 struct deadline_rq *drq = RQ_DATA(req);
359
360 /*
361 * hash always needs to be repositioned, key is end sector
362 */
363 deadline_del_drq_hash(drq);
364 deadline_add_drq_hash(dd, drq);
365
366 /*
367 * if the merge was a front merge, we need to reposition request
368 */
369 if (rq_rb_key(req) != drq->rb_key) {
370 deadline_del_drq_rb(dd, drq);
371 deadline_add_drq_rb(dd, drq);
372 }
373}
374
375static void
376deadline_merged_requests(request_queue_t *q, struct request *req,
377 struct request *next)
378{
379 struct deadline_data *dd = q->elevator->elevator_data;
380 struct deadline_rq *drq = RQ_DATA(req);
381 struct deadline_rq *dnext = RQ_DATA(next);
382
383 BUG_ON(!drq);
384 BUG_ON(!dnext);
385
386 /*
387 * reposition drq (this is the merged request) in hash, and in rbtree
388 * in case of a front merge
389 */
390 deadline_del_drq_hash(drq);
391 deadline_add_drq_hash(dd, drq);
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 /*
399 * if dnext expires before drq, assign its expire time to drq
400 * and move into dnext position (dnext will be deleted) in fifo
401 */
402 if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
403 if (time_before(dnext->expires, drq->expires)) {
404 list_move(&drq->fifo, &dnext->fifo);
405 drq->expires = dnext->expires;
406 }
407 }
408
409 /*
410 * kill knowledge of next, this one is a goner
411 */
412 deadline_remove_request(q, next);
413}
414
415/*
416 * move request from sort list to dispatch queue.
417 */
418static inline void
419deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
420{
421 request_queue_t *q = drq->request->q;
422
423 deadline_remove_request(q, drq->request);
424 elv_dispatch_add_tail(q, drq->request);
425}
426
427/*
428 * move an entry to dispatch queue
429 */
430static void
431deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
432{
433 const int data_dir = rq_data_dir(drq->request);
434 struct rb_node *rbnext = rb_next(&drq->rb_node);
435
436 dd->next_drq[READ] = NULL;
437 dd->next_drq[WRITE] = NULL;
438
439 if (rbnext)
440 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
441
442 dd->last_sector = drq->request->sector + drq->request->nr_sectors;
443
444 /*
445 * take it off the sort and fifo list, move
446 * to dispatch queue
447 */
448 deadline_move_to_dispatch(dd, drq);
449}
450
451#define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo)
452
453/*
454 * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
455 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
456 */
457static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
458{
459 struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
460
461 /*
462 * drq is expired!
463 */
464 if (time_after(jiffies, drq->expires))
465 return 1;
466
467 return 0;
468}
469
470/*
471 * deadline_dispatch_requests selects the best request according to
472 * read/write expire, fifo_batch, etc
473 */
474static int deadline_dispatch_requests(request_queue_t *q, int force)
475{
476 struct deadline_data *dd = q->elevator->elevator_data;
477 const int reads = !list_empty(&dd->fifo_list[READ]);
478 const int writes = !list_empty(&dd->fifo_list[WRITE]);
479 struct deadline_rq *drq;
480 int data_dir;
481
482 /*
483 * batches are currently reads XOR writes
484 */
485 if (dd->next_drq[WRITE])
486 drq = dd->next_drq[WRITE];
487 else
488 drq = dd->next_drq[READ];
489
490 if (drq) {
491 /* we have a "next request" */
492
493 if (dd->last_sector != drq->request->sector)
494 /* end the batch on a non sequential request */
495 dd->batching += dd->fifo_batch;
496
497 if (dd->batching < dd->fifo_batch)
498 /* we are still entitled to batch */
499 goto dispatch_request;
500 }
501
502 /*
503 * at this point we are not running a batch. select the appropriate
504 * data direction (read / write)
505 */
506
507 if (reads) {
508 BUG_ON(RB_EMPTY(&dd->sort_list[READ]));
509
510 if (writes && (dd->starved++ >= dd->writes_starved))
511 goto dispatch_writes;
512
513 data_dir = READ;
514
515 goto dispatch_find_request;
516 }
517
518 /*
519 * there are either no reads or writes have been starved
520 */
521
522 if (writes) {
523dispatch_writes:
524 BUG_ON(RB_EMPTY(&dd->sort_list[WRITE]));
525
526 dd->starved = 0;
527
528 data_dir = WRITE;
529
530 goto dispatch_find_request;
531 }
532
533 return 0;
534
535dispatch_find_request:
536 /*
537 * we are not running a batch, find best request for selected data_dir
538 */
539 if (deadline_check_fifo(dd, data_dir)) {
540 /* An expired request exists - satisfy it */
541 dd->batching = 0;
542 drq = list_entry_fifo(dd->fifo_list[data_dir].next);
543
544 } else if (dd->next_drq[data_dir]) {
545 /*
546 * The last req was the same dir and we have a next request in
547 * sort order. No expired requests so continue on from here.
548 */
549 drq = dd->next_drq[data_dir];
550 } else {
551 /*
552 * The last req was the other direction or we have run out of
553 * higher-sectored requests. Go back to the lowest sectored
554 * request (1 way elevator) and start a new batch.
555 */
556 dd->batching = 0;
557 drq = deadline_find_first_drq(dd, data_dir);
558 }
559
560dispatch_request:
561 /*
562 * drq is the selected appropriate request.
563 */
564 dd->batching++;
565 deadline_move_request(dd, drq);
566
567 return 1;
568}
569
570static int deadline_queue_empty(request_queue_t *q)
571{
572 struct deadline_data *dd = q->elevator->elevator_data;
573
574 return list_empty(&dd->fifo_list[WRITE])
575 && list_empty(&dd->fifo_list[READ]);
576}
577
578static struct request *
579deadline_former_request(request_queue_t *q, struct request *rq)
580{
581 struct deadline_rq *drq = RQ_DATA(rq);
582 struct rb_node *rbprev = rb_prev(&drq->rb_node);
583
584 if (rbprev)
585 return rb_entry_drq(rbprev)->request;
586
587 return NULL;
588}
589
590static struct request *
591deadline_latter_request(request_queue_t *q, struct request *rq)
592{
593 struct deadline_rq *drq = RQ_DATA(rq);
594 struct rb_node *rbnext = rb_next(&drq->rb_node);
595
596 if (rbnext)
597 return rb_entry_drq(rbnext)->request;
598
599 return NULL;
600}
601
602static void deadline_exit_queue(elevator_t *e)
603{
604 struct deadline_data *dd = e->elevator_data;
605
606 BUG_ON(!list_empty(&dd->fifo_list[READ]));
607 BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
608
609 mempool_destroy(dd->drq_pool);
610 kfree(dd->hash);
611 kfree(dd);
612}
613
614/*
615 * initialize elevator private data (deadline_data), and alloc a drq for
616 * each request on the free lists
617 */
618static int deadline_init_queue(request_queue_t *q, elevator_t *e)
619{
620 struct deadline_data *dd;
621 int i;
622
623 if (!drq_pool)
624 return -ENOMEM;
625
626 dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
627 if (!dd)
628 return -ENOMEM;
629 memset(dd, 0, sizeof(*dd));
630
631 dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
632 GFP_KERNEL, q->node);
633 if (!dd->hash) {
634 kfree(dd);
635 return -ENOMEM;
636 }
637
638 dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
639 mempool_free_slab, drq_pool, q->node);
640 if (!dd->drq_pool) {
641 kfree(dd->hash);
642 kfree(dd);
643 return -ENOMEM;
644 }
645
646 for (i = 0; i < DL_HASH_ENTRIES; i++)
647 INIT_LIST_HEAD(&dd->hash[i]);
648
649 INIT_LIST_HEAD(&dd->fifo_list[READ]);
650 INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
651 dd->sort_list[READ] = RB_ROOT;
652 dd->sort_list[WRITE] = RB_ROOT;
653 dd->fifo_expire[READ] = read_expire;
654 dd->fifo_expire[WRITE] = write_expire;
655 dd->writes_starved = writes_starved;
656 dd->front_merges = 1;
657 dd->fifo_batch = fifo_batch;
658 e->elevator_data = dd;
659 return 0;
660}
661
662static void deadline_put_request(request_queue_t *q, struct request *rq)
663{
664 struct deadline_data *dd = q->elevator->elevator_data;
665 struct deadline_rq *drq = RQ_DATA(rq);
666
667 mempool_free(drq, dd->drq_pool);
668 rq->elevator_private = NULL;
669}
670
671static int
672deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
673 gfp_t gfp_mask)
674{
675 struct deadline_data *dd = q->elevator->elevator_data;
676 struct deadline_rq *drq;
677
678 drq = mempool_alloc(dd->drq_pool, gfp_mask);
679 if (drq) {
680 memset(drq, 0, sizeof(*drq));
681 RB_CLEAR(&drq->rb_node);
682 drq->request = rq;
683
684 INIT_LIST_HEAD(&drq->hash);
685 drq->on_hash = 0;
686
687 INIT_LIST_HEAD(&drq->fifo);
688
689 rq->elevator_private = drq;
690 return 0;
691 }
692
693 return 1;
694}
695
696/*
697 * sysfs parts below
698 */
699struct deadline_fs_entry {
700 struct attribute attr;
701 ssize_t (*show)(struct deadline_data *, char *);
702 ssize_t (*store)(struct deadline_data *, const char *, size_t);
703};
704
705static ssize_t
706deadline_var_show(int var, char *page)
707{
708 return sprintf(page, "%d\n", var);
709}
710
711static ssize_t
712deadline_var_store(int *var, const char *page, size_t count)
713{
714 char *p = (char *) page;
715
716 *var = simple_strtol(p, &p, 10);
717 return count;
718}
719
720#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
721static ssize_t __FUNC(struct deadline_data *dd, char *page) \
722{ \
723 int __data = __VAR; \
724 if (__CONV) \
725 __data = jiffies_to_msecs(__data); \
726 return deadline_var_show(__data, (page)); \
727}
728SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1);
729SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1);
730SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0);
731SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0);
732SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0);
733#undef SHOW_FUNCTION
734
735#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
736static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \
737{ \
738 int __data; \
739 int ret = deadline_var_store(&__data, (page), count); \
740 if (__data < (MIN)) \
741 __data = (MIN); \
742 else if (__data > (MAX)) \
743 __data = (MAX); \
744 if (__CONV) \
745 *(__PTR) = msecs_to_jiffies(__data); \
746 else \
747 *(__PTR) = __data; \
748 return ret; \
749}
750STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
751STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
752STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
753STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0);
754STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0);
755#undef STORE_FUNCTION
756
757static struct deadline_fs_entry deadline_readexpire_entry = {
758 .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
759 .show = deadline_readexpire_show,
760 .store = deadline_readexpire_store,
761};
762static struct deadline_fs_entry deadline_writeexpire_entry = {
763 .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
764 .show = deadline_writeexpire_show,
765 .store = deadline_writeexpire_store,
766};
767static struct deadline_fs_entry deadline_writesstarved_entry = {
768 .attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR },
769 .show = deadline_writesstarved_show,
770 .store = deadline_writesstarved_store,
771};
772static struct deadline_fs_entry deadline_frontmerges_entry = {
773 .attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR },
774 .show = deadline_frontmerges_show,
775 .store = deadline_frontmerges_store,
776};
777static struct deadline_fs_entry deadline_fifobatch_entry = {
778 .attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR },
779 .show = deadline_fifobatch_show,
780 .store = deadline_fifobatch_store,
781};
782
783static struct attribute *default_attrs[] = {
784 &deadline_readexpire_entry.attr,
785 &deadline_writeexpire_entry.attr,
786 &deadline_writesstarved_entry.attr,
787 &deadline_frontmerges_entry.attr,
788 &deadline_fifobatch_entry.attr,
789 NULL,
790};
791
792#define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr)
793
794static ssize_t
795deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
796{
797 elevator_t *e = container_of(kobj, elevator_t, kobj);
798 struct deadline_fs_entry *entry = to_deadline(attr);
799
800 if (!entry->show)
801 return -EIO;
802
803 return entry->show(e->elevator_data, page);
804}
805
806static ssize_t
807deadline_attr_store(struct kobject *kobj, struct attribute *attr,
808 const char *page, size_t length)
809{
810 elevator_t *e = container_of(kobj, elevator_t, kobj);
811 struct deadline_fs_entry *entry = to_deadline(attr);
812
813 if (!entry->store)
814 return -EIO;
815
816 return entry->store(e->elevator_data, page, length);
817}
818
819static struct sysfs_ops deadline_sysfs_ops = {
820 .show = deadline_attr_show,
821 .store = deadline_attr_store,
822};
823
824static struct kobj_type deadline_ktype = {
825 .sysfs_ops = &deadline_sysfs_ops,
826 .default_attrs = default_attrs,
827};
828
829static struct elevator_type iosched_deadline = {
830 .ops = {
831 .elevator_merge_fn = deadline_merge,
832 .elevator_merged_fn = deadline_merged_request,
833 .elevator_merge_req_fn = deadline_merged_requests,
834 .elevator_dispatch_fn = deadline_dispatch_requests,
835 .elevator_add_req_fn = deadline_add_request,
836 .elevator_queue_empty_fn = deadline_queue_empty,
837 .elevator_former_req_fn = deadline_former_request,
838 .elevator_latter_req_fn = deadline_latter_request,
839 .elevator_set_req_fn = deadline_set_request,
840 .elevator_put_req_fn = deadline_put_request,
841 .elevator_init_fn = deadline_init_queue,
842 .elevator_exit_fn = deadline_exit_queue,
843 },
844
845 .elevator_ktype = &deadline_ktype,
846 .elevator_name = "deadline",
847 .elevator_owner = THIS_MODULE,
848};
849
850static int __init deadline_init(void)
851{
852 int ret;
853
854 drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
855 0, 0, NULL, NULL);
856
857 if (!drq_pool)
858 return -ENOMEM;
859
860 ret = elv_register(&iosched_deadline);
861 if (ret)
862 kmem_cache_destroy(drq_pool);
863
864 return ret;
865}
866
867static void __exit deadline_exit(void)
868{
869 kmem_cache_destroy(drq_pool);
870 elv_unregister(&iosched_deadline);
871}
872
873module_init(deadline_init);
874module_exit(deadline_exit);
875
876MODULE_AUTHOR("Jens Axboe");
877MODULE_LICENSE("GPL");
878MODULE_DESCRIPTION("deadline IO scheduler");
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-01 03:36:10 -0400