blob: 87ca02ac84cb1d5a6f77f5377c6ec8f4e7492d55 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Deadline i/o scheduler.
3 *
Jens Axboe0fe23472006-09-04 15:41:16 +02004 * Copyright (C) 2002 Jens Axboe <axboe@kernel.dk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 */
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/module.h>
12#include <linux/slab.h>
13#include <linux/init.h>
14#include <linux/compiler.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/rbtree.h>
16
17/*
18 * See Documentation/block/deadline-iosched.txt
19 */
Arjan van de Ven64100092006-01-06 09:46:02 +010020static const int read_expire = HZ / 2; /* max time before a read is submitted. */
21static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
22static const int writes_starved = 2; /* max times reads can starve a write */
23static const int fifo_batch = 16; /* # of sequential requests treated as one
Linus Torvalds1da177e2005-04-16 15:20:36 -070024 by the above parameters. For throughput. */
25
Linus Torvalds1da177e2005-04-16 15:20:36 -070026struct deadline_data {
27 /*
28 * run time data
29 */
30
31 /*
32 * requests (deadline_rq s) are present on both sort_list and fifo_list
33 */
34 struct rb_root sort_list[2];
35 struct list_head fifo_list[2];
36
37 /*
38 * next in sort order. read, write or both are NULL
39 */
Jens Axboe8840faa2006-07-13 12:36:41 +020040 struct request *next_rq[2];
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 unsigned int batching; /* number of sequential requests made */
42 sector_t last_sector; /* head position */
43 unsigned int starved; /* times reads have starved writes */
44
45 /*
46 * settings that change how the i/o scheduler behaves
47 */
48 int fifo_expire[2];
49 int fifo_batch;
50 int writes_starved;
51 int front_merges;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052};
53
Jens Axboe8840faa2006-07-13 12:36:41 +020054static void deadline_move_request(struct deadline_data *, struct request *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
Jens Axboeb8aca352006-07-13 12:34:24 +020056#define RQ_RB_ROOT(dd, rq) (&(dd)->sort_list[rq_data_dir((rq))])
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
58static void
Jens Axboe8840faa2006-07-13 12:36:41 +020059deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070060{
Jens Axboeb8aca352006-07-13 12:34:24 +020061 struct rb_root *root = RQ_RB_ROOT(dd, rq);
62 struct request *__alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
64retry:
Jens Axboeb8aca352006-07-13 12:34:24 +020065 __alias = elv_rb_add(root, rq);
66 if (unlikely(__alias)) {
Jens Axboe8840faa2006-07-13 12:36:41 +020067 deadline_move_request(dd, __alias);
Jens Axboeb8aca352006-07-13 12:34:24 +020068 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070070}
71
72static inline void
Jens Axboe8840faa2006-07-13 12:36:41 +020073deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074{
Jens Axboeb8aca352006-07-13 12:34:24 +020075 const int data_dir = rq_data_dir(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
Jens Axboe8840faa2006-07-13 12:36:41 +020077 if (dd->next_rq[data_dir] == rq) {
Jens Axboeb8aca352006-07-13 12:34:24 +020078 struct rb_node *rbnext = rb_next(&rq->rb_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
Jens Axboe8840faa2006-07-13 12:36:41 +020080 dd->next_rq[data_dir] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 if (rbnext)
Jens Axboe8840faa2006-07-13 12:36:41 +020082 dd->next_rq[data_dir] = rb_entry_rq(rbnext);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 }
84
Jens Axboeb8aca352006-07-13 12:34:24 +020085 elv_rb_del(RQ_RB_ROOT(dd, rq), rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086}
87
88/*
Jens Axboe8840faa2006-07-13 12:36:41 +020089 * add rq to rbtree and fifo
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 */
Jens Axboeb4878f22005-10-20 16:42:29 +020091static void
Linus Torvalds1da177e2005-04-16 15:20:36 -070092deadline_add_request(struct request_queue *q, struct request *rq)
93{
94 struct deadline_data *dd = q->elevator->elevator_data;
Jens Axboe8840faa2006-07-13 12:36:41 +020095 const int data_dir = rq_data_dir(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
Jens Axboe8840faa2006-07-13 12:36:41 +020097 deadline_add_rq_rb(dd, rq);
Jens Axboe98170642006-07-28 09:23:08 +020098
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 /*
100 * set expire time (only used for reads) and add to fifo list
101 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200102 rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
103 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104}
105
106/*
Jens Axboe98170642006-07-28 09:23:08 +0200107 * remove rq from rbtree and fifo.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 */
109static void deadline_remove_request(request_queue_t *q, struct request *rq)
110{
Jens Axboeb4878f22005-10-20 16:42:29 +0200111 struct deadline_data *dd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
Jens Axboe8840faa2006-07-13 12:36:41 +0200113 rq_fifo_clear(rq);
114 deadline_del_rq_rb(dd, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115}
116
117static int
118deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
119{
120 struct deadline_data *dd = q->elevator->elevator_data;
121 struct request *__rq;
122 int ret;
123
124 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 * check for front merge
126 */
127 if (dd->front_merges) {
Jens Axboeb8aca352006-07-13 12:34:24 +0200128 sector_t sector = bio->bi_sector + bio_sectors(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Jens Axboeb8aca352006-07-13 12:34:24 +0200130 __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 if (__rq) {
Jens Axboeb8aca352006-07-13 12:34:24 +0200132 BUG_ON(sector != __rq->sector);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
134 if (elv_rq_merge_ok(__rq, bio)) {
135 ret = ELEVATOR_FRONT_MERGE;
136 goto out;
137 }
138 }
139 }
140
141 return ELEVATOR_NO_MERGE;
142out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 *req = __rq;
144 return ret;
145}
146
Jens Axboeb8aca352006-07-13 12:34:24 +0200147static void deadline_merged_request(request_queue_t *q, struct request *req,
148 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149{
150 struct deadline_data *dd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 * if the merge was a front merge, we need to reposition request
154 */
Jens Axboeb8aca352006-07-13 12:34:24 +0200155 if (type == ELEVATOR_FRONT_MERGE) {
156 elv_rb_del(RQ_RB_ROOT(dd, req), req);
Jens Axboe8840faa2006-07-13 12:36:41 +0200157 deadline_add_rq_rb(dd, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159}
160
161static void
162deadline_merged_requests(request_queue_t *q, struct request *req,
163 struct request *next)
164{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 /*
Jens Axboe8840faa2006-07-13 12:36:41 +0200166 * if next expires before rq, assign its expire time to rq
167 * and move into next position (next will be deleted) in fifo
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200169 if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
170 if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
171 list_move(&req->queuelist, &next->queuelist);
172 rq_set_fifo_time(req, rq_fifo_time(next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 }
174 }
175
176 /*
177 * kill knowledge of next, this one is a goner
178 */
179 deadline_remove_request(q, next);
180}
181
182/*
183 * move request from sort list to dispatch queue.
184 */
185static inline void
Jens Axboe8840faa2006-07-13 12:36:41 +0200186deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187{
Jens Axboe8840faa2006-07-13 12:36:41 +0200188 request_queue_t *q = rq->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
Jens Axboe8840faa2006-07-13 12:36:41 +0200190 deadline_remove_request(q, rq);
191 elv_dispatch_add_tail(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192}
193
194/*
195 * move an entry to dispatch queue
196 */
197static void
Jens Axboe8840faa2006-07-13 12:36:41 +0200198deadline_move_request(struct deadline_data *dd, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199{
Jens Axboeb8aca352006-07-13 12:34:24 +0200200 const int data_dir = rq_data_dir(rq);
201 struct rb_node *rbnext = rb_next(&rq->rb_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
Jens Axboe8840faa2006-07-13 12:36:41 +0200203 dd->next_rq[READ] = NULL;
204 dd->next_rq[WRITE] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205
206 if (rbnext)
Jens Axboe8840faa2006-07-13 12:36:41 +0200207 dd->next_rq[data_dir] = rb_entry_rq(rbnext);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208
Jens Axboe8840faa2006-07-13 12:36:41 +0200209 dd->last_sector = rq->sector + rq->nr_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210
211 /*
212 * take it off the sort and fifo list, move
213 * to dispatch queue
214 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200215 deadline_move_to_dispatch(dd, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216}
217
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218/*
219 * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
220 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
221 */
222static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
223{
Jens Axboe8840faa2006-07-13 12:36:41 +0200224 struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
226 /*
Jens Axboe8840faa2006-07-13 12:36:41 +0200227 * rq is expired!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200229 if (time_after(jiffies, rq_fifo_time(rq)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 return 1;
231
232 return 0;
233}
234
235/*
236 * deadline_dispatch_requests selects the best request according to
237 * read/write expire, fifo_batch, etc
238 */
Jens Axboeb4878f22005-10-20 16:42:29 +0200239static int deadline_dispatch_requests(request_queue_t *q, int force)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240{
Jens Axboeb4878f22005-10-20 16:42:29 +0200241 struct deadline_data *dd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 const int reads = !list_empty(&dd->fifo_list[READ]);
243 const int writes = !list_empty(&dd->fifo_list[WRITE]);
Jens Axboe8840faa2006-07-13 12:36:41 +0200244 struct request *rq;
Nikita Danilov4b0dc072005-09-06 15:17:20 -0700245 int data_dir;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246
247 /*
248 * batches are currently reads XOR writes
249 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200250 if (dd->next_rq[WRITE])
251 rq = dd->next_rq[WRITE];
Andrew Morton9d5c1e12005-09-09 13:02:12 -0700252 else
Jens Axboe8840faa2006-07-13 12:36:41 +0200253 rq = dd->next_rq[READ];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
Jens Axboe8840faa2006-07-13 12:36:41 +0200255 if (rq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 /* we have a "next request" */
257
Jens Axboe8840faa2006-07-13 12:36:41 +0200258 if (dd->last_sector != rq->sector)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 /* end the batch on a non sequential request */
260 dd->batching += dd->fifo_batch;
261
262 if (dd->batching < dd->fifo_batch)
263 /* we are still entitled to batch */
264 goto dispatch_request;
265 }
266
267 /*
268 * at this point we are not running a batch. select the appropriate
269 * data direction (read / write)
270 */
271
272 if (reads) {
Jens Axboedd67d052006-06-21 09:36:18 +0200273 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274
275 if (writes && (dd->starved++ >= dd->writes_starved))
276 goto dispatch_writes;
277
278 data_dir = READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279
280 goto dispatch_find_request;
281 }
282
283 /*
284 * there are either no reads or writes have been starved
285 */
286
287 if (writes) {
288dispatch_writes:
Jens Axboedd67d052006-06-21 09:36:18 +0200289 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290
291 dd->starved = 0;
292
293 data_dir = WRITE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
295 goto dispatch_find_request;
296 }
297
298 return 0;
299
300dispatch_find_request:
301 /*
302 * we are not running a batch, find best request for selected data_dir
303 */
304 if (deadline_check_fifo(dd, data_dir)) {
305 /* An expired request exists - satisfy it */
306 dd->batching = 0;
Jens Axboe8840faa2006-07-13 12:36:41 +0200307 rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
Jens Axboe8840faa2006-07-13 12:36:41 +0200309 } else if (dd->next_rq[data_dir]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 /*
311 * The last req was the same dir and we have a next request in
312 * sort order. No expired requests so continue on from here.
313 */
Jens Axboe8840faa2006-07-13 12:36:41 +0200314 rq = dd->next_rq[data_dir];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 } else {
Jens Axboe8840faa2006-07-13 12:36:41 +0200316 struct rb_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 /*
318 * The last req was the other direction or we have run out of
319 * higher-sectored requests. Go back to the lowest sectored
320 * request (1 way elevator) and start a new batch.
321 */
322 dd->batching = 0;
Jens Axboe8840faa2006-07-13 12:36:41 +0200323 node = rb_first(&dd->sort_list[data_dir]);
324 if (node)
325 rq = rb_entry_rq(node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 }
327
328dispatch_request:
329 /*
Jens Axboe8840faa2006-07-13 12:36:41 +0200330 * rq is the selected appropriate request.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 */
332 dd->batching++;
Jens Axboe8840faa2006-07-13 12:36:41 +0200333 deadline_move_request(dd, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
335 return 1;
336}
337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338static int deadline_queue_empty(request_queue_t *q)
339{
340 struct deadline_data *dd = q->elevator->elevator_data;
341
Jens Axboeb4878f22005-10-20 16:42:29 +0200342 return list_empty(&dd->fifo_list[WRITE])
343 && list_empty(&dd->fifo_list[READ]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344}
345
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346static void deadline_exit_queue(elevator_t *e)
347{
348 struct deadline_data *dd = e->elevator_data;
349
350 BUG_ON(!list_empty(&dd->fifo_list[READ]));
351 BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
352
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 kfree(dd);
354}
355
356/*
Jens Axboe8840faa2006-07-13 12:36:41 +0200357 * initialize elevator private data (deadline_data).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 */
Jens Axboebb37b942006-12-01 10:42:33 +0100359static void *deadline_init_queue(request_queue_t *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360{
361 struct deadline_data *dd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
Christoph Lameter94f60302007-07-17 04:03:29 -0700363 dd = kmalloc_node(sizeof(*dd), GFP_KERNEL | __GFP_ZERO, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 if (!dd)
Jens Axboebc1c1162006-06-08 08:49:06 +0200365 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 INIT_LIST_HEAD(&dd->fifo_list[READ]);
368 INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
369 dd->sort_list[READ] = RB_ROOT;
370 dd->sort_list[WRITE] = RB_ROOT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 dd->fifo_expire[READ] = read_expire;
372 dd->fifo_expire[WRITE] = write_expire;
373 dd->writes_starved = writes_starved;
374 dd->front_merges = 1;
375 dd->fifo_batch = fifo_batch;
Jens Axboebc1c1162006-06-08 08:49:06 +0200376 return dd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377}
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379/*
380 * sysfs parts below
381 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383static ssize_t
384deadline_var_show(int var, char *page)
385{
386 return sprintf(page, "%d\n", var);
387}
388
389static ssize_t
390deadline_var_store(int *var, const char *page, size_t count)
391{
392 char *p = (char *) page;
393
394 *var = simple_strtol(p, &p, 10);
395 return count;
396}
397
398#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
Al Viro3d1ab402006-03-18 18:35:43 -0500399static ssize_t __FUNC(elevator_t *e, char *page) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400{ \
Al Viro3d1ab402006-03-18 18:35:43 -0500401 struct deadline_data *dd = e->elevator_data; \
402 int __data = __VAR; \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 if (__CONV) \
404 __data = jiffies_to_msecs(__data); \
405 return deadline_var_show(__data, (page)); \
406}
Al Viroe572ec72006-03-18 22:27:18 -0500407SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
408SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
409SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
410SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
411SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412#undef SHOW_FUNCTION
413
414#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
Al Viro3d1ab402006-03-18 18:35:43 -0500415static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416{ \
Al Viro3d1ab402006-03-18 18:35:43 -0500417 struct deadline_data *dd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 int __data; \
419 int ret = deadline_var_store(&__data, (page), count); \
420 if (__data < (MIN)) \
421 __data = (MIN); \
422 else if (__data > (MAX)) \
423 __data = (MAX); \
424 if (__CONV) \
425 *(__PTR) = msecs_to_jiffies(__data); \
426 else \
427 *(__PTR) = __data; \
428 return ret; \
429}
Al Viroe572ec72006-03-18 22:27:18 -0500430STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
431STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
432STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
433STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
434STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435#undef STORE_FUNCTION
436
Al Viroe572ec72006-03-18 22:27:18 -0500437#define DD_ATTR(name) \
438 __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
439 deadline_##name##_store)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440
Al Viroe572ec72006-03-18 22:27:18 -0500441static struct elv_fs_entry deadline_attrs[] = {
442 DD_ATTR(read_expire),
443 DD_ATTR(write_expire),
444 DD_ATTR(writes_starved),
445 DD_ATTR(front_merges),
446 DD_ATTR(fifo_batch),
447 __ATTR_NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448};
449
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450static struct elevator_type iosched_deadline = {
451 .ops = {
452 .elevator_merge_fn = deadline_merge,
453 .elevator_merged_fn = deadline_merged_request,
454 .elevator_merge_req_fn = deadline_merged_requests,
Jens Axboeb4878f22005-10-20 16:42:29 +0200455 .elevator_dispatch_fn = deadline_dispatch_requests,
456 .elevator_add_req_fn = deadline_add_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 .elevator_queue_empty_fn = deadline_queue_empty,
Jens Axboeb8aca352006-07-13 12:34:24 +0200458 .elevator_former_req_fn = elv_rb_former_request,
459 .elevator_latter_req_fn = elv_rb_latter_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 .elevator_init_fn = deadline_init_queue,
461 .elevator_exit_fn = deadline_exit_queue,
462 },
463
Al Viro3d1ab402006-03-18 18:35:43 -0500464 .elevator_attrs = deadline_attrs,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 .elevator_name = "deadline",
466 .elevator_owner = THIS_MODULE,
467};
468
469static int __init deadline_init(void)
470{
Jens Axboe8840faa2006-07-13 12:36:41 +0200471 return elv_register(&iosched_deadline);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472}
473
474static void __exit deadline_exit(void)
475{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 elv_unregister(&iosched_deadline);
477}
478
479module_init(deadline_init);
480module_exit(deadline_exit);
481
482MODULE_AUTHOR("Jens Axboe");
483MODULE_LICENSE("GPL");
484MODULE_DESCRIPTION("deadline IO scheduler");