Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | * Deadline i/o scheduler. |
| 3 | * |
Jens Axboe | 0fe2347 | 2006-09-04 15:41:16 +0200 | [diff] [blame] | 4 | * Copyright (C) 2002 Jens Axboe <axboe@kernel.dk> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/module.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/compiler.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/rbtree.h> |
| 16 | |
| 17 | /* |
| 18 | * See Documentation/block/deadline-iosched.txt |
| 19 | */ |
Arjan van de Ven | 6410009 | 2006-01-06 09:46:02 +0100 | [diff] [blame] | 20 | static const int read_expire = HZ / 2; /* max time before a read is submitted. */ |
| 21 | static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ |
| 22 | static const int writes_starved = 2; /* max times reads can starve a write */ |
| 23 | static const int fifo_batch = 16; /* # of sequential requests treated as one |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | by the above parameters. For throughput. */ |
| 25 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | struct 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 Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 40 | struct request *next_rq[2]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | 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 Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | }; |
| 53 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 54 | static void deadline_move_request(struct deadline_data *, struct request *); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 56 | #define RQ_RB_ROOT(dd, rq) (&(dd)->sort_list[rq_data_dir((rq))]) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | |
| 58 | static void |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 59 | deadline_add_rq_rb(struct deadline_data *dd, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 61 | struct rb_root *root = RQ_RB_ROOT(dd, rq); |
| 62 | struct request *__alias; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | |
| 64 | retry: |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 65 | __alias = elv_rb_add(root, rq); |
| 66 | if (unlikely(__alias)) { |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 67 | deadline_move_request(dd, __alias); |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 68 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | } |
| 71 | |
| 72 | static inline void |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 73 | deadline_del_rq_rb(struct deadline_data *dd, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 75 | const int data_dir = rq_data_dir(rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 76 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 77 | if (dd->next_rq[data_dir] == rq) { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 78 | struct rb_node *rbnext = rb_next(&rq->rb_node); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 79 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 80 | dd->next_rq[data_dir] = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 81 | if (rbnext) |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 82 | dd->next_rq[data_dir] = rb_entry_rq(rbnext); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | } |
| 84 | |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 85 | elv_rb_del(RQ_RB_ROOT(dd, rq), rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | } |
| 87 | |
| 88 | /* |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 89 | * add rq to rbtree and fifo |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | */ |
Jens Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 91 | static void |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | deadline_add_request(struct request_queue *q, struct request *rq) |
| 93 | { |
| 94 | struct deadline_data *dd = q->elevator->elevator_data; |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 95 | const int data_dir = rq_data_dir(rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 97 | deadline_add_rq_rb(dd, rq); |
Jens Axboe | 9817064 | 2006-07-28 09:23:08 +0200 | [diff] [blame] | 98 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | /* |
| 100 | * set expire time (only used for reads) and add to fifo list |
| 101 | */ |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 102 | rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]); |
| 103 | list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 104 | } |
| 105 | |
| 106 | /* |
Jens Axboe | 9817064 | 2006-07-28 09:23:08 +0200 | [diff] [blame] | 107 | * remove rq from rbtree and fifo. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | */ |
| 109 | static void deadline_remove_request(request_queue_t *q, struct request *rq) |
| 110 | { |
Jens Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 111 | struct deadline_data *dd = q->elevator->elevator_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 113 | rq_fifo_clear(rq); |
| 114 | deadline_del_rq_rb(dd, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | } |
| 116 | |
| 117 | static int |
| 118 | deadline_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 Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | * check for front merge |
| 126 | */ |
| 127 | if (dd->front_merges) { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 128 | sector_t sector = bio->bi_sector + bio_sectors(bio); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 130 | __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | if (__rq) { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 132 | BUG_ON(sector != __rq->sector); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | |
| 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; |
| 142 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | *req = __rq; |
| 144 | return ret; |
| 145 | } |
| 146 | |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 147 | static void deadline_merged_request(request_queue_t *q, struct request *req, |
| 148 | int type) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | { |
| 150 | struct deadline_data *dd = q->elevator->elevator_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | |
| 152 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 153 | * if the merge was a front merge, we need to reposition request |
| 154 | */ |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 155 | if (type == ELEVATOR_FRONT_MERGE) { |
| 156 | elv_rb_del(RQ_RB_ROOT(dd, req), req); |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 157 | deadline_add_rq_rb(dd, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 158 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 159 | } |
| 160 | |
| 161 | static void |
| 162 | deadline_merged_requests(request_queue_t *q, struct request *req, |
| 163 | struct request *next) |
| 164 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | /* |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 166 | * if next expires before rq, assign its expire time to rq |
| 167 | * and move into next position (next will be deleted) in fifo |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 168 | */ |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 169 | 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 Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 173 | } |
| 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 | */ |
| 185 | static inline void |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 186 | deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | { |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 188 | request_queue_t *q = rq->q; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 189 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 190 | deadline_remove_request(q, rq); |
| 191 | elv_dispatch_add_tail(q, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 192 | } |
| 193 | |
| 194 | /* |
| 195 | * move an entry to dispatch queue |
| 196 | */ |
| 197 | static void |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 198 | deadline_move_request(struct deadline_data *dd, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 199 | { |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 200 | const int data_dir = rq_data_dir(rq); |
| 201 | struct rb_node *rbnext = rb_next(&rq->rb_node); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 203 | dd->next_rq[READ] = NULL; |
| 204 | dd->next_rq[WRITE] = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 205 | |
| 206 | if (rbnext) |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 207 | dd->next_rq[data_dir] = rb_entry_rq(rbnext); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 208 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 209 | dd->last_sector = rq->sector + rq->nr_sectors; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | |
| 211 | /* |
| 212 | * take it off the sort and fifo list, move |
| 213 | * to dispatch queue |
| 214 | */ |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 215 | deadline_move_to_dispatch(dd, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 216 | } |
| 217 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | /* |
| 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 | */ |
| 222 | static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) |
| 223 | { |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 224 | struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | |
| 226 | /* |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 227 | * rq is expired! |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 228 | */ |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 229 | if (time_after(jiffies, rq_fifo_time(rq))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | 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 Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 239 | static int deadline_dispatch_requests(request_queue_t *q, int force) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 240 | { |
Jens Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 241 | struct deadline_data *dd = q->elevator->elevator_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | const int reads = !list_empty(&dd->fifo_list[READ]); |
| 243 | const int writes = !list_empty(&dd->fifo_list[WRITE]); |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 244 | struct request *rq; |
Nikita Danilov | 4b0dc07 | 2005-09-06 15:17:20 -0700 | [diff] [blame] | 245 | int data_dir; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | |
| 247 | /* |
| 248 | * batches are currently reads XOR writes |
| 249 | */ |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 250 | if (dd->next_rq[WRITE]) |
| 251 | rq = dd->next_rq[WRITE]; |
Andrew Morton | 9d5c1e1 | 2005-09-09 13:02:12 -0700 | [diff] [blame] | 252 | else |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 253 | rq = dd->next_rq[READ]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 254 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 255 | if (rq) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 256 | /* we have a "next request" */ |
| 257 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 258 | if (dd->last_sector != rq->sector) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 259 | /* 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 Axboe | dd67d05 | 2006-06-21 09:36:18 +0200 | [diff] [blame] | 273 | BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ])); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 274 | |
| 275 | if (writes && (dd->starved++ >= dd->writes_starved)) |
| 276 | goto dispatch_writes; |
| 277 | |
| 278 | data_dir = READ; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 279 | |
| 280 | goto dispatch_find_request; |
| 281 | } |
| 282 | |
| 283 | /* |
| 284 | * there are either no reads or writes have been starved |
| 285 | */ |
| 286 | |
| 287 | if (writes) { |
| 288 | dispatch_writes: |
Jens Axboe | dd67d05 | 2006-06-21 09:36:18 +0200 | [diff] [blame] | 289 | BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE])); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 290 | |
| 291 | dd->starved = 0; |
| 292 | |
| 293 | data_dir = WRITE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 294 | |
| 295 | goto dispatch_find_request; |
| 296 | } |
| 297 | |
| 298 | return 0; |
| 299 | |
| 300 | dispatch_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 Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 307 | rq = rq_entry_fifo(dd->fifo_list[data_dir].next); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 308 | |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 309 | } else if (dd->next_rq[data_dir]) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 310 | /* |
| 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 Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 314 | rq = dd->next_rq[data_dir]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 315 | } else { |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 316 | struct rb_node *node; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 317 | /* |
| 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 Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 323 | node = rb_first(&dd->sort_list[data_dir]); |
| 324 | if (node) |
| 325 | rq = rb_entry_rq(node); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 326 | } |
| 327 | |
| 328 | dispatch_request: |
| 329 | /* |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 330 | * rq is the selected appropriate request. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 331 | */ |
| 332 | dd->batching++; |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 333 | deadline_move_request(dd, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 334 | |
| 335 | return 1; |
| 336 | } |
| 337 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | static int deadline_queue_empty(request_queue_t *q) |
| 339 | { |
| 340 | struct deadline_data *dd = q->elevator->elevator_data; |
| 341 | |
Jens Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 342 | return list_empty(&dd->fifo_list[WRITE]) |
| 343 | && list_empty(&dd->fifo_list[READ]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 344 | } |
| 345 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 346 | static 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 Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 353 | kfree(dd); |
| 354 | } |
| 355 | |
| 356 | /* |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 357 | * initialize elevator private data (deadline_data). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 358 | */ |
Jens Axboe | bb37b94 | 2006-12-01 10:42:33 +0100 | [diff] [blame^] | 359 | static void *deadline_init_queue(request_queue_t *q) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 360 | { |
| 361 | struct deadline_data *dd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 362 | |
Christoph Lameter | 1946089 | 2005-06-23 00:08:19 -0700 | [diff] [blame] | 363 | dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 364 | if (!dd) |
Jens Axboe | bc1c116 | 2006-06-08 08:49:06 +0200 | [diff] [blame] | 365 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 366 | memset(dd, 0, sizeof(*dd)); |
| 367 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 368 | INIT_LIST_HEAD(&dd->fifo_list[READ]); |
| 369 | INIT_LIST_HEAD(&dd->fifo_list[WRITE]); |
| 370 | dd->sort_list[READ] = RB_ROOT; |
| 371 | dd->sort_list[WRITE] = RB_ROOT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 372 | dd->fifo_expire[READ] = read_expire; |
| 373 | dd->fifo_expire[WRITE] = write_expire; |
| 374 | dd->writes_starved = writes_starved; |
| 375 | dd->front_merges = 1; |
| 376 | dd->fifo_batch = fifo_batch; |
Jens Axboe | bc1c116 | 2006-06-08 08:49:06 +0200 | [diff] [blame] | 377 | return dd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 378 | } |
| 379 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | /* |
| 381 | * sysfs parts below |
| 382 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 383 | |
| 384 | static ssize_t |
| 385 | deadline_var_show(int var, char *page) |
| 386 | { |
| 387 | return sprintf(page, "%d\n", var); |
| 388 | } |
| 389 | |
| 390 | static ssize_t |
| 391 | deadline_var_store(int *var, const char *page, size_t count) |
| 392 | { |
| 393 | char *p = (char *) page; |
| 394 | |
| 395 | *var = simple_strtol(p, &p, 10); |
| 396 | return count; |
| 397 | } |
| 398 | |
| 399 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 400 | static ssize_t __FUNC(elevator_t *e, char *page) \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 401 | { \ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 402 | struct deadline_data *dd = e->elevator_data; \ |
| 403 | int __data = __VAR; \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 404 | if (__CONV) \ |
| 405 | __data = jiffies_to_msecs(__data); \ |
| 406 | return deadline_var_show(__data, (page)); \ |
| 407 | } |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 408 | SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1); |
| 409 | SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1); |
| 410 | SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0); |
| 411 | SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0); |
| 412 | SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 413 | #undef SHOW_FUNCTION |
| 414 | |
| 415 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 416 | static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 417 | { \ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 418 | struct deadline_data *dd = e->elevator_data; \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 419 | int __data; \ |
| 420 | int ret = deadline_var_store(&__data, (page), count); \ |
| 421 | if (__data < (MIN)) \ |
| 422 | __data = (MIN); \ |
| 423 | else if (__data > (MAX)) \ |
| 424 | __data = (MAX); \ |
| 425 | if (__CONV) \ |
| 426 | *(__PTR) = msecs_to_jiffies(__data); \ |
| 427 | else \ |
| 428 | *(__PTR) = __data; \ |
| 429 | return ret; \ |
| 430 | } |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 431 | STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); |
| 432 | STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); |
| 433 | STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); |
| 434 | STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0); |
| 435 | STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 436 | #undef STORE_FUNCTION |
| 437 | |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 438 | #define DD_ATTR(name) \ |
| 439 | __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \ |
| 440 | deadline_##name##_store) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 441 | |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 442 | static struct elv_fs_entry deadline_attrs[] = { |
| 443 | DD_ATTR(read_expire), |
| 444 | DD_ATTR(write_expire), |
| 445 | DD_ATTR(writes_starved), |
| 446 | DD_ATTR(front_merges), |
| 447 | DD_ATTR(fifo_batch), |
| 448 | __ATTR_NULL |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 449 | }; |
| 450 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 451 | static struct elevator_type iosched_deadline = { |
| 452 | .ops = { |
| 453 | .elevator_merge_fn = deadline_merge, |
| 454 | .elevator_merged_fn = deadline_merged_request, |
| 455 | .elevator_merge_req_fn = deadline_merged_requests, |
Jens Axboe | b4878f2 | 2005-10-20 16:42:29 +0200 | [diff] [blame] | 456 | .elevator_dispatch_fn = deadline_dispatch_requests, |
| 457 | .elevator_add_req_fn = deadline_add_request, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 458 | .elevator_queue_empty_fn = deadline_queue_empty, |
Jens Axboe | b8aca35 | 2006-07-13 12:34:24 +0200 | [diff] [blame] | 459 | .elevator_former_req_fn = elv_rb_former_request, |
| 460 | .elevator_latter_req_fn = elv_rb_latter_request, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 461 | .elevator_init_fn = deadline_init_queue, |
| 462 | .elevator_exit_fn = deadline_exit_queue, |
| 463 | }, |
| 464 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 465 | .elevator_attrs = deadline_attrs, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 466 | .elevator_name = "deadline", |
| 467 | .elevator_owner = THIS_MODULE, |
| 468 | }; |
| 469 | |
| 470 | static int __init deadline_init(void) |
| 471 | { |
Jens Axboe | 8840faa | 2006-07-13 12:36:41 +0200 | [diff] [blame] | 472 | return elv_register(&iosched_deadline); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 473 | } |
| 474 | |
| 475 | static void __exit deadline_exit(void) |
| 476 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 477 | elv_unregister(&iosched_deadline); |
| 478 | } |
| 479 | |
| 480 | module_init(deadline_init); |
| 481 | module_exit(deadline_exit); |
| 482 | |
| 483 | MODULE_AUTHOR("Jens Axboe"); |
| 484 | MODULE_LICENSE("GPL"); |
| 485 | MODULE_DESCRIPTION("deadline IO scheduler"); |