| 1 | /* |
| 2 | * CFQ, or complete fairness queueing, disk scheduler. |
| 3 | * |
| 4 | * Based on ideas from a previously unfinished io |
| 5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. |
| 6 | * |
| 7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
| 8 | */ |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/blkdev.h> |
| 11 | #include <linux/elevator.h> |
| 12 | #include <linux/jiffies.h> |
| 13 | #include <linux/rbtree.h> |
| 14 | #include <linux/ioprio.h> |
| 15 | #include <linux/blktrace_api.h> |
| 16 | |
| 17 | /* |
| 18 | * tunables |
| 19 | */ |
| 20 | /* max queue in one round of service */ |
| 21 | static const int cfq_quantum = 4; |
| 22 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
| 23 | /* maximum backwards seek, in KiB */ |
| 24 | static const int cfq_back_max = 16 * 1024; |
| 25 | /* penalty of a backwards seek */ |
| 26 | static const int cfq_back_penalty = 2; |
| 27 | static const int cfq_slice_sync = HZ / 10; |
| 28 | static int cfq_slice_async = HZ / 25; |
| 29 | static const int cfq_slice_async_rq = 2; |
| 30 | static int cfq_slice_idle = HZ / 125; |
| 31 | static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ |
| 32 | static const int cfq_hist_divisor = 4; |
| 33 | |
| 34 | /* |
| 35 | * offset from end of service tree |
| 36 | */ |
| 37 | #define CFQ_IDLE_DELAY (HZ / 5) |
| 38 | |
| 39 | /* |
| 40 | * below this threshold, we consider thinktime immediate |
| 41 | */ |
| 42 | #define CFQ_MIN_TT (2) |
| 43 | |
| 44 | /* |
| 45 | * Allow merged cfqqs to perform this amount of seeky I/O before |
| 46 | * deciding to break the queues up again. |
| 47 | */ |
| 48 | #define CFQQ_COOP_TOUT (HZ) |
| 49 | |
| 50 | #define CFQ_SLICE_SCALE (5) |
| 51 | #define CFQ_HW_QUEUE_MIN (5) |
| 52 | |
| 53 | #define RQ_CIC(rq) \ |
| 54 | ((struct cfq_io_context *) (rq)->elevator_private) |
| 55 | #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) |
| 56 | |
| 57 | static struct kmem_cache *cfq_pool; |
| 58 | static struct kmem_cache *cfq_ioc_pool; |
| 59 | |
| 60 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
| 61 | static struct completion *ioc_gone; |
| 62 | static DEFINE_SPINLOCK(ioc_gone_lock); |
| 63 | |
| 64 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
| 65 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) |
| 66 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
| 67 | |
| 68 | #define sample_valid(samples) ((samples) > 80) |
| 69 | |
| 70 | /* |
| 71 | * Most of our rbtree usage is for sorting with min extraction, so |
| 72 | * if we cache the leftmost node we don't have to walk down the tree |
| 73 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should |
| 74 | * move this into the elevator for the rq sorting as well. |
| 75 | */ |
| 76 | struct cfq_rb_root { |
| 77 | struct rb_root rb; |
| 78 | struct rb_node *left; |
| 79 | unsigned count; |
| 80 | }; |
| 81 | #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, } |
| 82 | |
| 83 | /* |
| 84 | * Per process-grouping structure |
| 85 | */ |
| 86 | struct cfq_queue { |
| 87 | /* reference count */ |
| 88 | atomic_t ref; |
| 89 | /* various state flags, see below */ |
| 90 | unsigned int flags; |
| 91 | /* parent cfq_data */ |
| 92 | struct cfq_data *cfqd; |
| 93 | /* service_tree member */ |
| 94 | struct rb_node rb_node; |
| 95 | /* service_tree key */ |
| 96 | unsigned long rb_key; |
| 97 | /* prio tree member */ |
| 98 | struct rb_node p_node; |
| 99 | /* prio tree root we belong to, if any */ |
| 100 | struct rb_root *p_root; |
| 101 | /* sorted list of pending requests */ |
| 102 | struct rb_root sort_list; |
| 103 | /* if fifo isn't expired, next request to serve */ |
| 104 | struct request *next_rq; |
| 105 | /* requests queued in sort_list */ |
| 106 | int queued[2]; |
| 107 | /* currently allocated requests */ |
| 108 | int allocated[2]; |
| 109 | /* fifo list of requests in sort_list */ |
| 110 | struct list_head fifo; |
| 111 | |
| 112 | unsigned long slice_end; |
| 113 | long slice_resid; |
| 114 | unsigned int slice_dispatch; |
| 115 | |
| 116 | /* pending metadata requests */ |
| 117 | int meta_pending; |
| 118 | /* number of requests that are on the dispatch list or inside driver */ |
| 119 | int dispatched; |
| 120 | |
| 121 | /* io prio of this group */ |
| 122 | unsigned short ioprio, org_ioprio; |
| 123 | unsigned short ioprio_class, org_ioprio_class; |
| 124 | |
| 125 | unsigned int seek_samples; |
| 126 | u64 seek_total; |
| 127 | sector_t seek_mean; |
| 128 | sector_t last_request_pos; |
| 129 | unsigned long seeky_start; |
| 130 | |
| 131 | pid_t pid; |
| 132 | |
| 133 | struct cfq_rb_root *service_tree; |
| 134 | struct cfq_queue *new_cfqq; |
| 135 | }; |
| 136 | |
| 137 | /* |
| 138 | * First index in the service_trees. |
| 139 | * IDLE is handled separately, so it has negative index |
| 140 | */ |
| 141 | enum wl_prio_t { |
| 142 | IDLE_WORKLOAD = -1, |
| 143 | BE_WORKLOAD = 0, |
| 144 | RT_WORKLOAD = 1 |
| 145 | }; |
| 146 | |
| 147 | /* |
| 148 | * Second index in the service_trees. |
| 149 | */ |
| 150 | enum wl_type_t { |
| 151 | ASYNC_WORKLOAD = 0, |
| 152 | SYNC_NOIDLE_WORKLOAD = 1, |
| 153 | SYNC_WORKLOAD = 2 |
| 154 | }; |
| 155 | |
| 156 | |
| 157 | /* |
| 158 | * Per block device queue structure |
| 159 | */ |
| 160 | struct cfq_data { |
| 161 | struct request_queue *queue; |
| 162 | |
| 163 | /* |
| 164 | * rr lists of queues with requests, onle rr for each priority class. |
| 165 | * Counts are embedded in the cfq_rb_root |
| 166 | */ |
| 167 | struct cfq_rb_root service_trees[2][3]; |
| 168 | struct cfq_rb_root service_tree_idle; |
| 169 | /* |
| 170 | * The priority currently being served |
| 171 | */ |
| 172 | enum wl_prio_t serving_prio; |
| 173 | enum wl_type_t serving_type; |
| 174 | unsigned long workload_expires; |
| 175 | bool noidle_tree_requires_idle; |
| 176 | |
| 177 | /* |
| 178 | * Each priority tree is sorted by next_request position. These |
| 179 | * trees are used when determining if two or more queues are |
| 180 | * interleaving requests (see cfq_close_cooperator). |
| 181 | */ |
| 182 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; |
| 183 | |
| 184 | unsigned int busy_queues; |
| 185 | unsigned int busy_queues_avg[2]; |
| 186 | |
| 187 | int rq_in_driver[2]; |
| 188 | int sync_flight; |
| 189 | |
| 190 | /* |
| 191 | * queue-depth detection |
| 192 | */ |
| 193 | int rq_queued; |
| 194 | int hw_tag; |
| 195 | /* |
| 196 | * hw_tag can be |
| 197 | * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) |
| 198 | * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) |
| 199 | * 0 => no NCQ |
| 200 | */ |
| 201 | int hw_tag_est_depth; |
| 202 | unsigned int hw_tag_samples; |
| 203 | |
| 204 | /* |
| 205 | * idle window management |
| 206 | */ |
| 207 | struct timer_list idle_slice_timer; |
| 208 | struct work_struct unplug_work; |
| 209 | |
| 210 | struct cfq_queue *active_queue; |
| 211 | struct cfq_io_context *active_cic; |
| 212 | |
| 213 | /* |
| 214 | * async queue for each priority case |
| 215 | */ |
| 216 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; |
| 217 | struct cfq_queue *async_idle_cfqq; |
| 218 | |
| 219 | sector_t last_position; |
| 220 | |
| 221 | /* |
| 222 | * tunables, see top of file |
| 223 | */ |
| 224 | unsigned int cfq_quantum; |
| 225 | unsigned int cfq_fifo_expire[2]; |
| 226 | unsigned int cfq_back_penalty; |
| 227 | unsigned int cfq_back_max; |
| 228 | unsigned int cfq_slice[2]; |
| 229 | unsigned int cfq_slice_async_rq; |
| 230 | unsigned int cfq_slice_idle; |
| 231 | unsigned int cfq_latency; |
| 232 | |
| 233 | struct list_head cic_list; |
| 234 | |
| 235 | /* |
| 236 | * Fallback dummy cfqq for extreme OOM conditions |
| 237 | */ |
| 238 | struct cfq_queue oom_cfqq; |
| 239 | |
| 240 | unsigned long last_end_sync_rq; |
| 241 | }; |
| 242 | |
| 243 | static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio, |
| 244 | enum wl_type_t type, |
| 245 | struct cfq_data *cfqd) |
| 246 | { |
| 247 | if (prio == IDLE_WORKLOAD) |
| 248 | return &cfqd->service_tree_idle; |
| 249 | |
| 250 | return &cfqd->service_trees[prio][type]; |
| 251 | } |
| 252 | |
| 253 | enum cfqq_state_flags { |
| 254 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
| 255 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ |
| 256 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
| 257 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
| 258 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
| 259 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ |
| 260 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ |
| 261 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
| 262 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
| 263 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
| 264 | CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ |
| 265 | }; |
| 266 | |
| 267 | #define CFQ_CFQQ_FNS(name) \ |
| 268 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ |
| 269 | { \ |
| 270 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
| 271 | } \ |
| 272 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ |
| 273 | { \ |
| 274 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
| 275 | } \ |
| 276 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ |
| 277 | { \ |
| 278 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
| 279 | } |
| 280 | |
| 281 | CFQ_CFQQ_FNS(on_rr); |
| 282 | CFQ_CFQQ_FNS(wait_request); |
| 283 | CFQ_CFQQ_FNS(must_dispatch); |
| 284 | CFQ_CFQQ_FNS(must_alloc_slice); |
| 285 | CFQ_CFQQ_FNS(fifo_expire); |
| 286 | CFQ_CFQQ_FNS(idle_window); |
| 287 | CFQ_CFQQ_FNS(prio_changed); |
| 288 | CFQ_CFQQ_FNS(slice_new); |
| 289 | CFQ_CFQQ_FNS(sync); |
| 290 | CFQ_CFQQ_FNS(coop); |
| 291 | CFQ_CFQQ_FNS(deep); |
| 292 | #undef CFQ_CFQQ_FNS |
| 293 | |
| 294 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
| 295 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) |
| 296 | #define cfq_log(cfqd, fmt, args...) \ |
| 297 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) |
| 298 | |
| 299 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
| 300 | { |
| 301 | if (cfq_class_idle(cfqq)) |
| 302 | return IDLE_WORKLOAD; |
| 303 | if (cfq_class_rt(cfqq)) |
| 304 | return RT_WORKLOAD; |
| 305 | return BE_WORKLOAD; |
| 306 | } |
| 307 | |
| 308 | |
| 309 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) |
| 310 | { |
| 311 | if (!cfq_cfqq_sync(cfqq)) |
| 312 | return ASYNC_WORKLOAD; |
| 313 | if (!cfq_cfqq_idle_window(cfqq)) |
| 314 | return SYNC_NOIDLE_WORKLOAD; |
| 315 | return SYNC_WORKLOAD; |
| 316 | } |
| 317 | |
| 318 | static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd) |
| 319 | { |
| 320 | if (wl == IDLE_WORKLOAD) |
| 321 | return cfqd->service_tree_idle.count; |
| 322 | |
| 323 | return cfqd->service_trees[wl][ASYNC_WORKLOAD].count |
| 324 | + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count |
| 325 | + cfqd->service_trees[wl][SYNC_WORKLOAD].count; |
| 326 | } |
| 327 | |
| 328 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
| 329 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
| 330 | struct io_context *, gfp_t); |
| 331 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
| 332 | struct io_context *); |
| 333 | |
| 334 | static inline int rq_in_driver(struct cfq_data *cfqd) |
| 335 | { |
| 336 | return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; |
| 337 | } |
| 338 | |
| 339 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
| 340 | bool is_sync) |
| 341 | { |
| 342 | return cic->cfqq[is_sync]; |
| 343 | } |
| 344 | |
| 345 | static inline void cic_set_cfqq(struct cfq_io_context *cic, |
| 346 | struct cfq_queue *cfqq, bool is_sync) |
| 347 | { |
| 348 | cic->cfqq[is_sync] = cfqq; |
| 349 | } |
| 350 | |
| 351 | /* |
| 352 | * We regard a request as SYNC, if it's either a read or has the SYNC bit |
| 353 | * set (in which case it could also be direct WRITE). |
| 354 | */ |
| 355 | static inline bool cfq_bio_sync(struct bio *bio) |
| 356 | { |
| 357 | return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); |
| 358 | } |
| 359 | |
| 360 | /* |
| 361 | * scheduler run of queue, if there are requests pending and no one in the |
| 362 | * driver that will restart queueing |
| 363 | */ |
| 364 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
| 365 | { |
| 366 | if (cfqd->busy_queues) { |
| 367 | cfq_log(cfqd, "schedule dispatch"); |
| 368 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
| 369 | } |
| 370 | } |
| 371 | |
| 372 | static int cfq_queue_empty(struct request_queue *q) |
| 373 | { |
| 374 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 375 | |
| 376 | return !cfqd->busy_queues; |
| 377 | } |
| 378 | |
| 379 | /* |
| 380 | * Scale schedule slice based on io priority. Use the sync time slice only |
| 381 | * if a queue is marked sync and has sync io queued. A sync queue with async |
| 382 | * io only, should not get full sync slice length. |
| 383 | */ |
| 384 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
| 385 | unsigned short prio) |
| 386 | { |
| 387 | const int base_slice = cfqd->cfq_slice[sync]; |
| 388 | |
| 389 | WARN_ON(prio >= IOPRIO_BE_NR); |
| 390 | |
| 391 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); |
| 392 | } |
| 393 | |
| 394 | static inline int |
| 395 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 396 | { |
| 397 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); |
| 398 | } |
| 399 | |
| 400 | /* |
| 401 | * get averaged number of queues of RT/BE priority. |
| 402 | * average is updated, with a formula that gives more weight to higher numbers, |
| 403 | * to quickly follows sudden increases and decrease slowly |
| 404 | */ |
| 405 | |
| 406 | static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt) |
| 407 | { |
| 408 | unsigned min_q, max_q; |
| 409 | unsigned mult = cfq_hist_divisor - 1; |
| 410 | unsigned round = cfq_hist_divisor / 2; |
| 411 | unsigned busy = cfq_busy_queues_wl(rt, cfqd); |
| 412 | |
| 413 | min_q = min(cfqd->busy_queues_avg[rt], busy); |
| 414 | max_q = max(cfqd->busy_queues_avg[rt], busy); |
| 415 | cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) / |
| 416 | cfq_hist_divisor; |
| 417 | return cfqd->busy_queues_avg[rt]; |
| 418 | } |
| 419 | |
| 420 | static inline void |
| 421 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 422 | { |
| 423 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
| 424 | if (cfqd->cfq_latency) { |
| 425 | /* interested queues (we consider only the ones with the same |
| 426 | * priority class) */ |
| 427 | unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); |
| 428 | unsigned sync_slice = cfqd->cfq_slice[1]; |
| 429 | unsigned expect_latency = sync_slice * iq; |
| 430 | if (expect_latency > cfq_target_latency) { |
| 431 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; |
| 432 | /* scale low_slice according to IO priority |
| 433 | * and sync vs async */ |
| 434 | unsigned low_slice = |
| 435 | min(slice, base_low_slice * slice / sync_slice); |
| 436 | /* the adapted slice value is scaled to fit all iqs |
| 437 | * into the target latency */ |
| 438 | slice = max(slice * cfq_target_latency / expect_latency, |
| 439 | low_slice); |
| 440 | } |
| 441 | } |
| 442 | cfqq->slice_end = jiffies + slice; |
| 443 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
| 444 | } |
| 445 | |
| 446 | /* |
| 447 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end |
| 448 | * isn't valid until the first request from the dispatch is activated |
| 449 | * and the slice time set. |
| 450 | */ |
| 451 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
| 452 | { |
| 453 | if (cfq_cfqq_slice_new(cfqq)) |
| 454 | return 0; |
| 455 | if (time_before(jiffies, cfqq->slice_end)) |
| 456 | return 0; |
| 457 | |
| 458 | return 1; |
| 459 | } |
| 460 | |
| 461 | /* |
| 462 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
| 463 | * We choose the request that is closest to the head right now. Distance |
| 464 | * behind the head is penalized and only allowed to a certain extent. |
| 465 | */ |
| 466 | static struct request * |
| 467 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
| 468 | { |
| 469 | sector_t s1, s2, d1 = 0, d2 = 0; |
| 470 | unsigned long back_max; |
| 471 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
| 472 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ |
| 473 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ |
| 474 | |
| 475 | if (rq1 == NULL || rq1 == rq2) |
| 476 | return rq2; |
| 477 | if (rq2 == NULL) |
| 478 | return rq1; |
| 479 | |
| 480 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
| 481 | return rq1; |
| 482 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) |
| 483 | return rq2; |
| 484 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
| 485 | return rq1; |
| 486 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) |
| 487 | return rq2; |
| 488 | |
| 489 | s1 = blk_rq_pos(rq1); |
| 490 | s2 = blk_rq_pos(rq2); |
| 491 | |
| 492 | /* |
| 493 | * by definition, 1KiB is 2 sectors |
| 494 | */ |
| 495 | back_max = cfqd->cfq_back_max * 2; |
| 496 | |
| 497 | /* |
| 498 | * Strict one way elevator _except_ in the case where we allow |
| 499 | * short backward seeks which are biased as twice the cost of a |
| 500 | * similar forward seek. |
| 501 | */ |
| 502 | if (s1 >= last) |
| 503 | d1 = s1 - last; |
| 504 | else if (s1 + back_max >= last) |
| 505 | d1 = (last - s1) * cfqd->cfq_back_penalty; |
| 506 | else |
| 507 | wrap |= CFQ_RQ1_WRAP; |
| 508 | |
| 509 | if (s2 >= last) |
| 510 | d2 = s2 - last; |
| 511 | else if (s2 + back_max >= last) |
| 512 | d2 = (last - s2) * cfqd->cfq_back_penalty; |
| 513 | else |
| 514 | wrap |= CFQ_RQ2_WRAP; |
| 515 | |
| 516 | /* Found required data */ |
| 517 | |
| 518 | /* |
| 519 | * By doing switch() on the bit mask "wrap" we avoid having to |
| 520 | * check two variables for all permutations: --> faster! |
| 521 | */ |
| 522 | switch (wrap) { |
| 523 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
| 524 | if (d1 < d2) |
| 525 | return rq1; |
| 526 | else if (d2 < d1) |
| 527 | return rq2; |
| 528 | else { |
| 529 | if (s1 >= s2) |
| 530 | return rq1; |
| 531 | else |
| 532 | return rq2; |
| 533 | } |
| 534 | |
| 535 | case CFQ_RQ2_WRAP: |
| 536 | return rq1; |
| 537 | case CFQ_RQ1_WRAP: |
| 538 | return rq2; |
| 539 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ |
| 540 | default: |
| 541 | /* |
| 542 | * Since both rqs are wrapped, |
| 543 | * start with the one that's further behind head |
| 544 | * (--> only *one* back seek required), |
| 545 | * since back seek takes more time than forward. |
| 546 | */ |
| 547 | if (s1 <= s2) |
| 548 | return rq1; |
| 549 | else |
| 550 | return rq2; |
| 551 | } |
| 552 | } |
| 553 | |
| 554 | /* |
| 555 | * The below is leftmost cache rbtree addon |
| 556 | */ |
| 557 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
| 558 | { |
| 559 | if (!root->left) |
| 560 | root->left = rb_first(&root->rb); |
| 561 | |
| 562 | if (root->left) |
| 563 | return rb_entry(root->left, struct cfq_queue, rb_node); |
| 564 | |
| 565 | return NULL; |
| 566 | } |
| 567 | |
| 568 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
| 569 | { |
| 570 | rb_erase(n, root); |
| 571 | RB_CLEAR_NODE(n); |
| 572 | } |
| 573 | |
| 574 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
| 575 | { |
| 576 | if (root->left == n) |
| 577 | root->left = NULL; |
| 578 | rb_erase_init(n, &root->rb); |
| 579 | --root->count; |
| 580 | } |
| 581 | |
| 582 | /* |
| 583 | * would be nice to take fifo expire time into account as well |
| 584 | */ |
| 585 | static struct request * |
| 586 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 587 | struct request *last) |
| 588 | { |
| 589 | struct rb_node *rbnext = rb_next(&last->rb_node); |
| 590 | struct rb_node *rbprev = rb_prev(&last->rb_node); |
| 591 | struct request *next = NULL, *prev = NULL; |
| 592 | |
| 593 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
| 594 | |
| 595 | if (rbprev) |
| 596 | prev = rb_entry_rq(rbprev); |
| 597 | |
| 598 | if (rbnext) |
| 599 | next = rb_entry_rq(rbnext); |
| 600 | else { |
| 601 | rbnext = rb_first(&cfqq->sort_list); |
| 602 | if (rbnext && rbnext != &last->rb_node) |
| 603 | next = rb_entry_rq(rbnext); |
| 604 | } |
| 605 | |
| 606 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
| 607 | } |
| 608 | |
| 609 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
| 610 | struct cfq_queue *cfqq) |
| 611 | { |
| 612 | /* |
| 613 | * just an approximation, should be ok. |
| 614 | */ |
| 615 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
| 616 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); |
| 617 | } |
| 618 | |
| 619 | /* |
| 620 | * The cfqd->service_trees holds all pending cfq_queue's that have |
| 621 | * requests waiting to be processed. It is sorted in the order that |
| 622 | * we will service the queues. |
| 623 | */ |
| 624 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 625 | bool add_front) |
| 626 | { |
| 627 | struct rb_node **p, *parent; |
| 628 | struct cfq_queue *__cfqq; |
| 629 | unsigned long rb_key; |
| 630 | struct cfq_rb_root *service_tree; |
| 631 | int left; |
| 632 | |
| 633 | service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd); |
| 634 | if (cfq_class_idle(cfqq)) { |
| 635 | rb_key = CFQ_IDLE_DELAY; |
| 636 | parent = rb_last(&service_tree->rb); |
| 637 | if (parent && parent != &cfqq->rb_node) { |
| 638 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| 639 | rb_key += __cfqq->rb_key; |
| 640 | } else |
| 641 | rb_key += jiffies; |
| 642 | } else if (!add_front) { |
| 643 | /* |
| 644 | * Get our rb key offset. Subtract any residual slice |
| 645 | * value carried from last service. A negative resid |
| 646 | * count indicates slice overrun, and this should position |
| 647 | * the next service time further away in the tree. |
| 648 | */ |
| 649 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
| 650 | rb_key -= cfqq->slice_resid; |
| 651 | cfqq->slice_resid = 0; |
| 652 | } else { |
| 653 | rb_key = -HZ; |
| 654 | __cfqq = cfq_rb_first(service_tree); |
| 655 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
| 656 | } |
| 657 | |
| 658 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
| 659 | /* |
| 660 | * same position, nothing more to do |
| 661 | */ |
| 662 | if (rb_key == cfqq->rb_key && |
| 663 | cfqq->service_tree == service_tree) |
| 664 | return; |
| 665 | |
| 666 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
| 667 | cfqq->service_tree = NULL; |
| 668 | } |
| 669 | |
| 670 | left = 1; |
| 671 | parent = NULL; |
| 672 | cfqq->service_tree = service_tree; |
| 673 | p = &service_tree->rb.rb_node; |
| 674 | while (*p) { |
| 675 | struct rb_node **n; |
| 676 | |
| 677 | parent = *p; |
| 678 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| 679 | |
| 680 | /* |
| 681 | * sort by key, that represents service time. |
| 682 | */ |
| 683 | if (time_before(rb_key, __cfqq->rb_key)) |
| 684 | n = &(*p)->rb_left; |
| 685 | else { |
| 686 | n = &(*p)->rb_right; |
| 687 | left = 0; |
| 688 | } |
| 689 | |
| 690 | p = n; |
| 691 | } |
| 692 | |
| 693 | if (left) |
| 694 | service_tree->left = &cfqq->rb_node; |
| 695 | |
| 696 | cfqq->rb_key = rb_key; |
| 697 | rb_link_node(&cfqq->rb_node, parent, p); |
| 698 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
| 699 | service_tree->count++; |
| 700 | } |
| 701 | |
| 702 | static struct cfq_queue * |
| 703 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
| 704 | sector_t sector, struct rb_node **ret_parent, |
| 705 | struct rb_node ***rb_link) |
| 706 | { |
| 707 | struct rb_node **p, *parent; |
| 708 | struct cfq_queue *cfqq = NULL; |
| 709 | |
| 710 | parent = NULL; |
| 711 | p = &root->rb_node; |
| 712 | while (*p) { |
| 713 | struct rb_node **n; |
| 714 | |
| 715 | parent = *p; |
| 716 | cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| 717 | |
| 718 | /* |
| 719 | * Sort strictly based on sector. Smallest to the left, |
| 720 | * largest to the right. |
| 721 | */ |
| 722 | if (sector > blk_rq_pos(cfqq->next_rq)) |
| 723 | n = &(*p)->rb_right; |
| 724 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
| 725 | n = &(*p)->rb_left; |
| 726 | else |
| 727 | break; |
| 728 | p = n; |
| 729 | cfqq = NULL; |
| 730 | } |
| 731 | |
| 732 | *ret_parent = parent; |
| 733 | if (rb_link) |
| 734 | *rb_link = p; |
| 735 | return cfqq; |
| 736 | } |
| 737 | |
| 738 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 739 | { |
| 740 | struct rb_node **p, *parent; |
| 741 | struct cfq_queue *__cfqq; |
| 742 | |
| 743 | if (cfqq->p_root) { |
| 744 | rb_erase(&cfqq->p_node, cfqq->p_root); |
| 745 | cfqq->p_root = NULL; |
| 746 | } |
| 747 | |
| 748 | if (cfq_class_idle(cfqq)) |
| 749 | return; |
| 750 | if (!cfqq->next_rq) |
| 751 | return; |
| 752 | |
| 753 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
| 754 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
| 755 | blk_rq_pos(cfqq->next_rq), &parent, &p); |
| 756 | if (!__cfqq) { |
| 757 | rb_link_node(&cfqq->p_node, parent, p); |
| 758 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
| 759 | } else |
| 760 | cfqq->p_root = NULL; |
| 761 | } |
| 762 | |
| 763 | /* |
| 764 | * Update cfqq's position in the service tree. |
| 765 | */ |
| 766 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 767 | { |
| 768 | /* |
| 769 | * Resorting requires the cfqq to be on the RR list already. |
| 770 | */ |
| 771 | if (cfq_cfqq_on_rr(cfqq)) { |
| 772 | cfq_service_tree_add(cfqd, cfqq, 0); |
| 773 | cfq_prio_tree_add(cfqd, cfqq); |
| 774 | } |
| 775 | } |
| 776 | |
| 777 | /* |
| 778 | * add to busy list of queues for service, trying to be fair in ordering |
| 779 | * the pending list according to last request service |
| 780 | */ |
| 781 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 782 | { |
| 783 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
| 784 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| 785 | cfq_mark_cfqq_on_rr(cfqq); |
| 786 | cfqd->busy_queues++; |
| 787 | |
| 788 | cfq_resort_rr_list(cfqd, cfqq); |
| 789 | } |
| 790 | |
| 791 | /* |
| 792 | * Called when the cfqq no longer has requests pending, remove it from |
| 793 | * the service tree. |
| 794 | */ |
| 795 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 796 | { |
| 797 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
| 798 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| 799 | cfq_clear_cfqq_on_rr(cfqq); |
| 800 | |
| 801 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
| 802 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
| 803 | cfqq->service_tree = NULL; |
| 804 | } |
| 805 | if (cfqq->p_root) { |
| 806 | rb_erase(&cfqq->p_node, cfqq->p_root); |
| 807 | cfqq->p_root = NULL; |
| 808 | } |
| 809 | |
| 810 | BUG_ON(!cfqd->busy_queues); |
| 811 | cfqd->busy_queues--; |
| 812 | } |
| 813 | |
| 814 | /* |
| 815 | * rb tree support functions |
| 816 | */ |
| 817 | static void cfq_del_rq_rb(struct request *rq) |
| 818 | { |
| 819 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 820 | struct cfq_data *cfqd = cfqq->cfqd; |
| 821 | const int sync = rq_is_sync(rq); |
| 822 | |
| 823 | BUG_ON(!cfqq->queued[sync]); |
| 824 | cfqq->queued[sync]--; |
| 825 | |
| 826 | elv_rb_del(&cfqq->sort_list, rq); |
| 827 | |
| 828 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
| 829 | cfq_del_cfqq_rr(cfqd, cfqq); |
| 830 | } |
| 831 | |
| 832 | static void cfq_add_rq_rb(struct request *rq) |
| 833 | { |
| 834 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 835 | struct cfq_data *cfqd = cfqq->cfqd; |
| 836 | struct request *__alias, *prev; |
| 837 | |
| 838 | cfqq->queued[rq_is_sync(rq)]++; |
| 839 | |
| 840 | /* |
| 841 | * looks a little odd, but the first insert might return an alias. |
| 842 | * if that happens, put the alias on the dispatch list |
| 843 | */ |
| 844 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
| 845 | cfq_dispatch_insert(cfqd->queue, __alias); |
| 846 | |
| 847 | if (!cfq_cfqq_on_rr(cfqq)) |
| 848 | cfq_add_cfqq_rr(cfqd, cfqq); |
| 849 | |
| 850 | /* |
| 851 | * check if this request is a better next-serve candidate |
| 852 | */ |
| 853 | prev = cfqq->next_rq; |
| 854 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
| 855 | |
| 856 | /* |
| 857 | * adjust priority tree position, if ->next_rq changes |
| 858 | */ |
| 859 | if (prev != cfqq->next_rq) |
| 860 | cfq_prio_tree_add(cfqd, cfqq); |
| 861 | |
| 862 | BUG_ON(!cfqq->next_rq); |
| 863 | } |
| 864 | |
| 865 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
| 866 | { |
| 867 | elv_rb_del(&cfqq->sort_list, rq); |
| 868 | cfqq->queued[rq_is_sync(rq)]--; |
| 869 | cfq_add_rq_rb(rq); |
| 870 | } |
| 871 | |
| 872 | static struct request * |
| 873 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) |
| 874 | { |
| 875 | struct task_struct *tsk = current; |
| 876 | struct cfq_io_context *cic; |
| 877 | struct cfq_queue *cfqq; |
| 878 | |
| 879 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
| 880 | if (!cic) |
| 881 | return NULL; |
| 882 | |
| 883 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| 884 | if (cfqq) { |
| 885 | sector_t sector = bio->bi_sector + bio_sectors(bio); |
| 886 | |
| 887 | return elv_rb_find(&cfqq->sort_list, sector); |
| 888 | } |
| 889 | |
| 890 | return NULL; |
| 891 | } |
| 892 | |
| 893 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
| 894 | { |
| 895 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 896 | |
| 897 | cfqd->rq_in_driver[rq_is_sync(rq)]++; |
| 898 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
| 899 | rq_in_driver(cfqd)); |
| 900 | |
| 901 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| 902 | } |
| 903 | |
| 904 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
| 905 | { |
| 906 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 907 | const int sync = rq_is_sync(rq); |
| 908 | |
| 909 | WARN_ON(!cfqd->rq_in_driver[sync]); |
| 910 | cfqd->rq_in_driver[sync]--; |
| 911 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
| 912 | rq_in_driver(cfqd)); |
| 913 | } |
| 914 | |
| 915 | static void cfq_remove_request(struct request *rq) |
| 916 | { |
| 917 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 918 | |
| 919 | if (cfqq->next_rq == rq) |
| 920 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); |
| 921 | |
| 922 | list_del_init(&rq->queuelist); |
| 923 | cfq_del_rq_rb(rq); |
| 924 | |
| 925 | cfqq->cfqd->rq_queued--; |
| 926 | if (rq_is_meta(rq)) { |
| 927 | WARN_ON(!cfqq->meta_pending); |
| 928 | cfqq->meta_pending--; |
| 929 | } |
| 930 | } |
| 931 | |
| 932 | static int cfq_merge(struct request_queue *q, struct request **req, |
| 933 | struct bio *bio) |
| 934 | { |
| 935 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 936 | struct request *__rq; |
| 937 | |
| 938 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
| 939 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
| 940 | *req = __rq; |
| 941 | return ELEVATOR_FRONT_MERGE; |
| 942 | } |
| 943 | |
| 944 | return ELEVATOR_NO_MERGE; |
| 945 | } |
| 946 | |
| 947 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
| 948 | int type) |
| 949 | { |
| 950 | if (type == ELEVATOR_FRONT_MERGE) { |
| 951 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
| 952 | |
| 953 | cfq_reposition_rq_rb(cfqq, req); |
| 954 | } |
| 955 | } |
| 956 | |
| 957 | static void |
| 958 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
| 959 | struct request *next) |
| 960 | { |
| 961 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 962 | /* |
| 963 | * reposition in fifo if next is older than rq |
| 964 | */ |
| 965 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && |
| 966 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
| 967 | list_move(&rq->queuelist, &next->queuelist); |
| 968 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
| 969 | } |
| 970 | |
| 971 | if (cfqq->next_rq == next) |
| 972 | cfqq->next_rq = rq; |
| 973 | cfq_remove_request(next); |
| 974 | } |
| 975 | |
| 976 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
| 977 | struct bio *bio) |
| 978 | { |
| 979 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 980 | struct cfq_io_context *cic; |
| 981 | struct cfq_queue *cfqq; |
| 982 | |
| 983 | /* |
| 984 | * Disallow merge of a sync bio into an async request. |
| 985 | */ |
| 986 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
| 987 | return false; |
| 988 | |
| 989 | /* |
| 990 | * Lookup the cfqq that this bio will be queued with. Allow |
| 991 | * merge only if rq is queued there. |
| 992 | */ |
| 993 | cic = cfq_cic_lookup(cfqd, current->io_context); |
| 994 | if (!cic) |
| 995 | return false; |
| 996 | |
| 997 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| 998 | return cfqq == RQ_CFQQ(rq); |
| 999 | } |
| 1000 | |
| 1001 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
| 1002 | struct cfq_queue *cfqq) |
| 1003 | { |
| 1004 | if (cfqq) { |
| 1005 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
| 1006 | cfqq->slice_end = 0; |
| 1007 | cfqq->slice_dispatch = 0; |
| 1008 | |
| 1009 | cfq_clear_cfqq_wait_request(cfqq); |
| 1010 | cfq_clear_cfqq_must_dispatch(cfqq); |
| 1011 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
| 1012 | cfq_clear_cfqq_fifo_expire(cfqq); |
| 1013 | cfq_mark_cfqq_slice_new(cfqq); |
| 1014 | |
| 1015 | del_timer(&cfqd->idle_slice_timer); |
| 1016 | } |
| 1017 | |
| 1018 | cfqd->active_queue = cfqq; |
| 1019 | } |
| 1020 | |
| 1021 | /* |
| 1022 | * current cfqq expired its slice (or was too idle), select new one |
| 1023 | */ |
| 1024 | static void |
| 1025 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 1026 | bool timed_out) |
| 1027 | { |
| 1028 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
| 1029 | |
| 1030 | if (cfq_cfqq_wait_request(cfqq)) |
| 1031 | del_timer(&cfqd->idle_slice_timer); |
| 1032 | |
| 1033 | cfq_clear_cfqq_wait_request(cfqq); |
| 1034 | |
| 1035 | /* |
| 1036 | * store what was left of this slice, if the queue idled/timed out |
| 1037 | */ |
| 1038 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
| 1039 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
| 1040 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
| 1041 | } |
| 1042 | |
| 1043 | cfq_resort_rr_list(cfqd, cfqq); |
| 1044 | |
| 1045 | if (cfqq == cfqd->active_queue) |
| 1046 | cfqd->active_queue = NULL; |
| 1047 | |
| 1048 | if (cfqd->active_cic) { |
| 1049 | put_io_context(cfqd->active_cic->ioc); |
| 1050 | cfqd->active_cic = NULL; |
| 1051 | } |
| 1052 | } |
| 1053 | |
| 1054 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
| 1055 | { |
| 1056 | struct cfq_queue *cfqq = cfqd->active_queue; |
| 1057 | |
| 1058 | if (cfqq) |
| 1059 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
| 1060 | } |
| 1061 | |
| 1062 | /* |
| 1063 | * Get next queue for service. Unless we have a queue preemption, |
| 1064 | * we'll simply select the first cfqq in the service tree. |
| 1065 | */ |
| 1066 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
| 1067 | { |
| 1068 | struct cfq_rb_root *service_tree = |
| 1069 | service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd); |
| 1070 | |
| 1071 | if (RB_EMPTY_ROOT(&service_tree->rb)) |
| 1072 | return NULL; |
| 1073 | return cfq_rb_first(service_tree); |
| 1074 | } |
| 1075 | |
| 1076 | /* |
| 1077 | * Get and set a new active queue for service. |
| 1078 | */ |
| 1079 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
| 1080 | struct cfq_queue *cfqq) |
| 1081 | { |
| 1082 | if (!cfqq) |
| 1083 | cfqq = cfq_get_next_queue(cfqd); |
| 1084 | |
| 1085 | __cfq_set_active_queue(cfqd, cfqq); |
| 1086 | return cfqq; |
| 1087 | } |
| 1088 | |
| 1089 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
| 1090 | struct request *rq) |
| 1091 | { |
| 1092 | if (blk_rq_pos(rq) >= cfqd->last_position) |
| 1093 | return blk_rq_pos(rq) - cfqd->last_position; |
| 1094 | else |
| 1095 | return cfqd->last_position - blk_rq_pos(rq); |
| 1096 | } |
| 1097 | |
| 1098 | #define CFQQ_SEEK_THR 8 * 1024 |
| 1099 | #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR) |
| 1100 | |
| 1101 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 1102 | struct request *rq) |
| 1103 | { |
| 1104 | sector_t sdist = cfqq->seek_mean; |
| 1105 | |
| 1106 | if (!sample_valid(cfqq->seek_samples)) |
| 1107 | sdist = CFQQ_SEEK_THR; |
| 1108 | |
| 1109 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
| 1110 | } |
| 1111 | |
| 1112 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
| 1113 | struct cfq_queue *cur_cfqq) |
| 1114 | { |
| 1115 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
| 1116 | struct rb_node *parent, *node; |
| 1117 | struct cfq_queue *__cfqq; |
| 1118 | sector_t sector = cfqd->last_position; |
| 1119 | |
| 1120 | if (RB_EMPTY_ROOT(root)) |
| 1121 | return NULL; |
| 1122 | |
| 1123 | /* |
| 1124 | * First, if we find a request starting at the end of the last |
| 1125 | * request, choose it. |
| 1126 | */ |
| 1127 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
| 1128 | if (__cfqq) |
| 1129 | return __cfqq; |
| 1130 | |
| 1131 | /* |
| 1132 | * If the exact sector wasn't found, the parent of the NULL leaf |
| 1133 | * will contain the closest sector. |
| 1134 | */ |
| 1135 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| 1136 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
| 1137 | return __cfqq; |
| 1138 | |
| 1139 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
| 1140 | node = rb_next(&__cfqq->p_node); |
| 1141 | else |
| 1142 | node = rb_prev(&__cfqq->p_node); |
| 1143 | if (!node) |
| 1144 | return NULL; |
| 1145 | |
| 1146 | __cfqq = rb_entry(node, struct cfq_queue, p_node); |
| 1147 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
| 1148 | return __cfqq; |
| 1149 | |
| 1150 | return NULL; |
| 1151 | } |
| 1152 | |
| 1153 | /* |
| 1154 | * cfqd - obvious |
| 1155 | * cur_cfqq - passed in so that we don't decide that the current queue is |
| 1156 | * closely cooperating with itself. |
| 1157 | * |
| 1158 | * So, basically we're assuming that that cur_cfqq has dispatched at least |
| 1159 | * one request, and that cfqd->last_position reflects a position on the disk |
| 1160 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid |
| 1161 | * assumption. |
| 1162 | */ |
| 1163 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, |
| 1164 | struct cfq_queue *cur_cfqq) |
| 1165 | { |
| 1166 | struct cfq_queue *cfqq; |
| 1167 | |
| 1168 | if (!cfq_cfqq_sync(cur_cfqq)) |
| 1169 | return NULL; |
| 1170 | if (CFQQ_SEEKY(cur_cfqq)) |
| 1171 | return NULL; |
| 1172 | |
| 1173 | /* |
| 1174 | * We should notice if some of the queues are cooperating, eg |
| 1175 | * working closely on the same area of the disk. In that case, |
| 1176 | * we can group them together and don't waste time idling. |
| 1177 | */ |
| 1178 | cfqq = cfqq_close(cfqd, cur_cfqq); |
| 1179 | if (!cfqq) |
| 1180 | return NULL; |
| 1181 | |
| 1182 | /* |
| 1183 | * It only makes sense to merge sync queues. |
| 1184 | */ |
| 1185 | if (!cfq_cfqq_sync(cfqq)) |
| 1186 | return NULL; |
| 1187 | if (CFQQ_SEEKY(cfqq)) |
| 1188 | return NULL; |
| 1189 | |
| 1190 | /* |
| 1191 | * Do not merge queues of different priority classes |
| 1192 | */ |
| 1193 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) |
| 1194 | return NULL; |
| 1195 | |
| 1196 | return cfqq; |
| 1197 | } |
| 1198 | |
| 1199 | /* |
| 1200 | * Determine whether we should enforce idle window for this queue. |
| 1201 | */ |
| 1202 | |
| 1203 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 1204 | { |
| 1205 | enum wl_prio_t prio = cfqq_prio(cfqq); |
| 1206 | struct cfq_rb_root *service_tree = cfqq->service_tree; |
| 1207 | |
| 1208 | /* We never do for idle class queues. */ |
| 1209 | if (prio == IDLE_WORKLOAD) |
| 1210 | return false; |
| 1211 | |
| 1212 | /* We do for queues that were marked with idle window flag. */ |
| 1213 | if (cfq_cfqq_idle_window(cfqq)) |
| 1214 | return true; |
| 1215 | |
| 1216 | /* |
| 1217 | * Otherwise, we do only if they are the last ones |
| 1218 | * in their service tree. |
| 1219 | */ |
| 1220 | if (!service_tree) |
| 1221 | service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd); |
| 1222 | |
| 1223 | if (service_tree->count == 0) |
| 1224 | return true; |
| 1225 | |
| 1226 | return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq); |
| 1227 | } |
| 1228 | |
| 1229 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
| 1230 | { |
| 1231 | struct cfq_queue *cfqq = cfqd->active_queue; |
| 1232 | struct cfq_io_context *cic; |
| 1233 | unsigned long sl; |
| 1234 | |
| 1235 | /* |
| 1236 | * SSD device without seek penalty, disable idling. But only do so |
| 1237 | * for devices that support queuing, otherwise we still have a problem |
| 1238 | * with sync vs async workloads. |
| 1239 | */ |
| 1240 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
| 1241 | return; |
| 1242 | |
| 1243 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
| 1244 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
| 1245 | |
| 1246 | /* |
| 1247 | * idle is disabled, either manually or by past process history |
| 1248 | */ |
| 1249 | if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) |
| 1250 | return; |
| 1251 | |
| 1252 | /* |
| 1253 | * still active requests from this queue, don't idle |
| 1254 | */ |
| 1255 | if (cfqq->dispatched) |
| 1256 | return; |
| 1257 | |
| 1258 | /* |
| 1259 | * task has exited, don't wait |
| 1260 | */ |
| 1261 | cic = cfqd->active_cic; |
| 1262 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
| 1263 | return; |
| 1264 | |
| 1265 | /* |
| 1266 | * If our average think time is larger than the remaining time |
| 1267 | * slice, then don't idle. This avoids overrunning the allotted |
| 1268 | * time slice. |
| 1269 | */ |
| 1270 | if (sample_valid(cic->ttime_samples) && |
| 1271 | (cfqq->slice_end - jiffies < cic->ttime_mean)) |
| 1272 | return; |
| 1273 | |
| 1274 | cfq_mark_cfqq_wait_request(cfqq); |
| 1275 | |
| 1276 | sl = cfqd->cfq_slice_idle; |
| 1277 | |
| 1278 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
| 1279 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
| 1280 | } |
| 1281 | |
| 1282 | /* |
| 1283 | * Move request from internal lists to the request queue dispatch list. |
| 1284 | */ |
| 1285 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
| 1286 | { |
| 1287 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 1288 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 1289 | |
| 1290 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
| 1291 | |
| 1292 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
| 1293 | cfq_remove_request(rq); |
| 1294 | cfqq->dispatched++; |
| 1295 | elv_dispatch_sort(q, rq); |
| 1296 | |
| 1297 | if (cfq_cfqq_sync(cfqq)) |
| 1298 | cfqd->sync_flight++; |
| 1299 | } |
| 1300 | |
| 1301 | /* |
| 1302 | * return expired entry, or NULL to just start from scratch in rbtree |
| 1303 | */ |
| 1304 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
| 1305 | { |
| 1306 | struct request *rq = NULL; |
| 1307 | |
| 1308 | if (cfq_cfqq_fifo_expire(cfqq)) |
| 1309 | return NULL; |
| 1310 | |
| 1311 | cfq_mark_cfqq_fifo_expire(cfqq); |
| 1312 | |
| 1313 | if (list_empty(&cfqq->fifo)) |
| 1314 | return NULL; |
| 1315 | |
| 1316 | rq = rq_entry_fifo(cfqq->fifo.next); |
| 1317 | if (time_before(jiffies, rq_fifo_time(rq))) |
| 1318 | rq = NULL; |
| 1319 | |
| 1320 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
| 1321 | return rq; |
| 1322 | } |
| 1323 | |
| 1324 | static inline int |
| 1325 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 1326 | { |
| 1327 | const int base_rq = cfqd->cfq_slice_async_rq; |
| 1328 | |
| 1329 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
| 1330 | |
| 1331 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
| 1332 | } |
| 1333 | |
| 1334 | /* |
| 1335 | * Must be called with the queue_lock held. |
| 1336 | */ |
| 1337 | static int cfqq_process_refs(struct cfq_queue *cfqq) |
| 1338 | { |
| 1339 | int process_refs, io_refs; |
| 1340 | |
| 1341 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; |
| 1342 | process_refs = atomic_read(&cfqq->ref) - io_refs; |
| 1343 | BUG_ON(process_refs < 0); |
| 1344 | return process_refs; |
| 1345 | } |
| 1346 | |
| 1347 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) |
| 1348 | { |
| 1349 | int process_refs, new_process_refs; |
| 1350 | struct cfq_queue *__cfqq; |
| 1351 | |
| 1352 | /* Avoid a circular list and skip interim queue merges */ |
| 1353 | while ((__cfqq = new_cfqq->new_cfqq)) { |
| 1354 | if (__cfqq == cfqq) |
| 1355 | return; |
| 1356 | new_cfqq = __cfqq; |
| 1357 | } |
| 1358 | |
| 1359 | process_refs = cfqq_process_refs(cfqq); |
| 1360 | /* |
| 1361 | * If the process for the cfqq has gone away, there is no |
| 1362 | * sense in merging the queues. |
| 1363 | */ |
| 1364 | if (process_refs == 0) |
| 1365 | return; |
| 1366 | |
| 1367 | /* |
| 1368 | * Merge in the direction of the lesser amount of work. |
| 1369 | */ |
| 1370 | new_process_refs = cfqq_process_refs(new_cfqq); |
| 1371 | if (new_process_refs >= process_refs) { |
| 1372 | cfqq->new_cfqq = new_cfqq; |
| 1373 | atomic_add(process_refs, &new_cfqq->ref); |
| 1374 | } else { |
| 1375 | new_cfqq->new_cfqq = cfqq; |
| 1376 | atomic_add(new_process_refs, &cfqq->ref); |
| 1377 | } |
| 1378 | } |
| 1379 | |
| 1380 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio, |
| 1381 | bool prio_changed) |
| 1382 | { |
| 1383 | struct cfq_queue *queue; |
| 1384 | int i; |
| 1385 | bool key_valid = false; |
| 1386 | unsigned long lowest_key = 0; |
| 1387 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; |
| 1388 | |
| 1389 | if (prio_changed) { |
| 1390 | /* |
| 1391 | * When priorities switched, we prefer starting |
| 1392 | * from SYNC_NOIDLE (first choice), or just SYNC |
| 1393 | * over ASYNC |
| 1394 | */ |
| 1395 | if (service_tree_for(prio, cur_best, cfqd)->count) |
| 1396 | return cur_best; |
| 1397 | cur_best = SYNC_WORKLOAD; |
| 1398 | if (service_tree_for(prio, cur_best, cfqd)->count) |
| 1399 | return cur_best; |
| 1400 | |
| 1401 | return ASYNC_WORKLOAD; |
| 1402 | } |
| 1403 | |
| 1404 | for (i = 0; i < 3; ++i) { |
| 1405 | /* otherwise, select the one with lowest rb_key */ |
| 1406 | queue = cfq_rb_first(service_tree_for(prio, i, cfqd)); |
| 1407 | if (queue && |
| 1408 | (!key_valid || time_before(queue->rb_key, lowest_key))) { |
| 1409 | lowest_key = queue->rb_key; |
| 1410 | cur_best = i; |
| 1411 | key_valid = true; |
| 1412 | } |
| 1413 | } |
| 1414 | |
| 1415 | return cur_best; |
| 1416 | } |
| 1417 | |
| 1418 | static void choose_service_tree(struct cfq_data *cfqd) |
| 1419 | { |
| 1420 | enum wl_prio_t previous_prio = cfqd->serving_prio; |
| 1421 | bool prio_changed; |
| 1422 | unsigned slice; |
| 1423 | unsigned count; |
| 1424 | |
| 1425 | /* Choose next priority. RT > BE > IDLE */ |
| 1426 | if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd)) |
| 1427 | cfqd->serving_prio = RT_WORKLOAD; |
| 1428 | else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd)) |
| 1429 | cfqd->serving_prio = BE_WORKLOAD; |
| 1430 | else { |
| 1431 | cfqd->serving_prio = IDLE_WORKLOAD; |
| 1432 | cfqd->workload_expires = jiffies + 1; |
| 1433 | return; |
| 1434 | } |
| 1435 | |
| 1436 | /* |
| 1437 | * For RT and BE, we have to choose also the type |
| 1438 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload |
| 1439 | * expiration time |
| 1440 | */ |
| 1441 | prio_changed = (cfqd->serving_prio != previous_prio); |
| 1442 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) |
| 1443 | ->count; |
| 1444 | |
| 1445 | /* |
| 1446 | * If priority didn't change, check workload expiration, |
| 1447 | * and that we still have other queues ready |
| 1448 | */ |
| 1449 | if (!prio_changed && count && |
| 1450 | !time_after(jiffies, cfqd->workload_expires)) |
| 1451 | return; |
| 1452 | |
| 1453 | /* otherwise select new workload type */ |
| 1454 | cfqd->serving_type = |
| 1455 | cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed); |
| 1456 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) |
| 1457 | ->count; |
| 1458 | |
| 1459 | /* |
| 1460 | * the workload slice is computed as a fraction of target latency |
| 1461 | * proportional to the number of queues in that workload, over |
| 1462 | * all the queues in the same priority class |
| 1463 | */ |
| 1464 | slice = cfq_target_latency * count / |
| 1465 | max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio], |
| 1466 | cfq_busy_queues_wl(cfqd->serving_prio, cfqd)); |
| 1467 | |
| 1468 | if (cfqd->serving_type == ASYNC_WORKLOAD) |
| 1469 | /* async workload slice is scaled down according to |
| 1470 | * the sync/async slice ratio. */ |
| 1471 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; |
| 1472 | else |
| 1473 | /* sync workload slice is at least 2 * cfq_slice_idle */ |
| 1474 | slice = max(slice, 2 * cfqd->cfq_slice_idle); |
| 1475 | |
| 1476 | slice = max_t(unsigned, slice, CFQ_MIN_TT); |
| 1477 | cfqd->workload_expires = jiffies + slice; |
| 1478 | cfqd->noidle_tree_requires_idle = false; |
| 1479 | } |
| 1480 | |
| 1481 | /* |
| 1482 | * Select a queue for service. If we have a current active queue, |
| 1483 | * check whether to continue servicing it, or retrieve and set a new one. |
| 1484 | */ |
| 1485 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
| 1486 | { |
| 1487 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
| 1488 | |
| 1489 | cfqq = cfqd->active_queue; |
| 1490 | if (!cfqq) |
| 1491 | goto new_queue; |
| 1492 | |
| 1493 | /* |
| 1494 | * The active queue has run out of time, expire it and select new. |
| 1495 | */ |
| 1496 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
| 1497 | goto expire; |
| 1498 | |
| 1499 | /* |
| 1500 | * The active queue has requests and isn't expired, allow it to |
| 1501 | * dispatch. |
| 1502 | */ |
| 1503 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
| 1504 | goto keep_queue; |
| 1505 | |
| 1506 | /* |
| 1507 | * If another queue has a request waiting within our mean seek |
| 1508 | * distance, let it run. The expire code will check for close |
| 1509 | * cooperators and put the close queue at the front of the service |
| 1510 | * tree. If possible, merge the expiring queue with the new cfqq. |
| 1511 | */ |
| 1512 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
| 1513 | if (new_cfqq) { |
| 1514 | if (!cfqq->new_cfqq) |
| 1515 | cfq_setup_merge(cfqq, new_cfqq); |
| 1516 | goto expire; |
| 1517 | } |
| 1518 | |
| 1519 | /* |
| 1520 | * No requests pending. If the active queue still has requests in |
| 1521 | * flight or is idling for a new request, allow either of these |
| 1522 | * conditions to happen (or time out) before selecting a new queue. |
| 1523 | */ |
| 1524 | if (timer_pending(&cfqd->idle_slice_timer) || |
| 1525 | (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { |
| 1526 | cfqq = NULL; |
| 1527 | goto keep_queue; |
| 1528 | } |
| 1529 | |
| 1530 | expire: |
| 1531 | cfq_slice_expired(cfqd, 0); |
| 1532 | new_queue: |
| 1533 | /* |
| 1534 | * Current queue expired. Check if we have to switch to a new |
| 1535 | * service tree |
| 1536 | */ |
| 1537 | if (!new_cfqq) |
| 1538 | choose_service_tree(cfqd); |
| 1539 | |
| 1540 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
| 1541 | keep_queue: |
| 1542 | return cfqq; |
| 1543 | } |
| 1544 | |
| 1545 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
| 1546 | { |
| 1547 | int dispatched = 0; |
| 1548 | |
| 1549 | while (cfqq->next_rq) { |
| 1550 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); |
| 1551 | dispatched++; |
| 1552 | } |
| 1553 | |
| 1554 | BUG_ON(!list_empty(&cfqq->fifo)); |
| 1555 | return dispatched; |
| 1556 | } |
| 1557 | |
| 1558 | /* |
| 1559 | * Drain our current requests. Used for barriers and when switching |
| 1560 | * io schedulers on-the-fly. |
| 1561 | */ |
| 1562 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
| 1563 | { |
| 1564 | struct cfq_queue *cfqq; |
| 1565 | int dispatched = 0; |
| 1566 | int i, j; |
| 1567 | for (i = 0; i < 2; ++i) |
| 1568 | for (j = 0; j < 3; ++j) |
| 1569 | while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j])) |
| 1570 | != NULL) |
| 1571 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
| 1572 | |
| 1573 | while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL) |
| 1574 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
| 1575 | |
| 1576 | cfq_slice_expired(cfqd, 0); |
| 1577 | |
| 1578 | BUG_ON(cfqd->busy_queues); |
| 1579 | |
| 1580 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
| 1581 | return dispatched; |
| 1582 | } |
| 1583 | |
| 1584 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 1585 | { |
| 1586 | unsigned int max_dispatch; |
| 1587 | |
| 1588 | /* |
| 1589 | * Drain async requests before we start sync IO |
| 1590 | */ |
| 1591 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) |
| 1592 | return false; |
| 1593 | |
| 1594 | /* |
| 1595 | * If this is an async queue and we have sync IO in flight, let it wait |
| 1596 | */ |
| 1597 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) |
| 1598 | return false; |
| 1599 | |
| 1600 | max_dispatch = cfqd->cfq_quantum; |
| 1601 | if (cfq_class_idle(cfqq)) |
| 1602 | max_dispatch = 1; |
| 1603 | |
| 1604 | /* |
| 1605 | * Does this cfqq already have too much IO in flight? |
| 1606 | */ |
| 1607 | if (cfqq->dispatched >= max_dispatch) { |
| 1608 | /* |
| 1609 | * idle queue must always only have a single IO in flight |
| 1610 | */ |
| 1611 | if (cfq_class_idle(cfqq)) |
| 1612 | return false; |
| 1613 | |
| 1614 | /* |
| 1615 | * We have other queues, don't allow more IO from this one |
| 1616 | */ |
| 1617 | if (cfqd->busy_queues > 1) |
| 1618 | return false; |
| 1619 | |
| 1620 | /* |
| 1621 | * Sole queue user, allow bigger slice |
| 1622 | */ |
| 1623 | max_dispatch *= 4; |
| 1624 | } |
| 1625 | |
| 1626 | /* |
| 1627 | * Async queues must wait a bit before being allowed dispatch. |
| 1628 | * We also ramp up the dispatch depth gradually for async IO, |
| 1629 | * based on the last sync IO we serviced |
| 1630 | */ |
| 1631 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
| 1632 | unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
| 1633 | unsigned int depth; |
| 1634 | |
| 1635 | depth = last_sync / cfqd->cfq_slice[1]; |
| 1636 | if (!depth && !cfqq->dispatched) |
| 1637 | depth = 1; |
| 1638 | if (depth < max_dispatch) |
| 1639 | max_dispatch = depth; |
| 1640 | } |
| 1641 | |
| 1642 | /* |
| 1643 | * If we're below the current max, allow a dispatch |
| 1644 | */ |
| 1645 | return cfqq->dispatched < max_dispatch; |
| 1646 | } |
| 1647 | |
| 1648 | /* |
| 1649 | * Dispatch a request from cfqq, moving them to the request queue |
| 1650 | * dispatch list. |
| 1651 | */ |
| 1652 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 1653 | { |
| 1654 | struct request *rq; |
| 1655 | |
| 1656 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
| 1657 | |
| 1658 | if (!cfq_may_dispatch(cfqd, cfqq)) |
| 1659 | return false; |
| 1660 | |
| 1661 | /* |
| 1662 | * follow expired path, else get first next available |
| 1663 | */ |
| 1664 | rq = cfq_check_fifo(cfqq); |
| 1665 | if (!rq) |
| 1666 | rq = cfqq->next_rq; |
| 1667 | |
| 1668 | /* |
| 1669 | * insert request into driver dispatch list |
| 1670 | */ |
| 1671 | cfq_dispatch_insert(cfqd->queue, rq); |
| 1672 | |
| 1673 | if (!cfqd->active_cic) { |
| 1674 | struct cfq_io_context *cic = RQ_CIC(rq); |
| 1675 | |
| 1676 | atomic_long_inc(&cic->ioc->refcount); |
| 1677 | cfqd->active_cic = cic; |
| 1678 | } |
| 1679 | |
| 1680 | return true; |
| 1681 | } |
| 1682 | |
| 1683 | /* |
| 1684 | * Find the cfqq that we need to service and move a request from that to the |
| 1685 | * dispatch list |
| 1686 | */ |
| 1687 | static int cfq_dispatch_requests(struct request_queue *q, int force) |
| 1688 | { |
| 1689 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 1690 | struct cfq_queue *cfqq; |
| 1691 | |
| 1692 | if (!cfqd->busy_queues) |
| 1693 | return 0; |
| 1694 | |
| 1695 | if (unlikely(force)) |
| 1696 | return cfq_forced_dispatch(cfqd); |
| 1697 | |
| 1698 | cfqq = cfq_select_queue(cfqd); |
| 1699 | if (!cfqq) |
| 1700 | return 0; |
| 1701 | |
| 1702 | /* |
| 1703 | * Dispatch a request from this cfqq, if it is allowed |
| 1704 | */ |
| 1705 | if (!cfq_dispatch_request(cfqd, cfqq)) |
| 1706 | return 0; |
| 1707 | |
| 1708 | cfqq->slice_dispatch++; |
| 1709 | cfq_clear_cfqq_must_dispatch(cfqq); |
| 1710 | |
| 1711 | /* |
| 1712 | * expire an async queue immediately if it has used up its slice. idle |
| 1713 | * queue always expire after 1 dispatch round. |
| 1714 | */ |
| 1715 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
| 1716 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
| 1717 | cfq_class_idle(cfqq))) { |
| 1718 | cfqq->slice_end = jiffies + 1; |
| 1719 | cfq_slice_expired(cfqd, 0); |
| 1720 | } |
| 1721 | |
| 1722 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
| 1723 | return 1; |
| 1724 | } |
| 1725 | |
| 1726 | /* |
| 1727 | * task holds one reference to the queue, dropped when task exits. each rq |
| 1728 | * in-flight on this queue also holds a reference, dropped when rq is freed. |
| 1729 | * |
| 1730 | * queue lock must be held here. |
| 1731 | */ |
| 1732 | static void cfq_put_queue(struct cfq_queue *cfqq) |
| 1733 | { |
| 1734 | struct cfq_data *cfqd = cfqq->cfqd; |
| 1735 | |
| 1736 | BUG_ON(atomic_read(&cfqq->ref) <= 0); |
| 1737 | |
| 1738 | if (!atomic_dec_and_test(&cfqq->ref)) |
| 1739 | return; |
| 1740 | |
| 1741 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
| 1742 | BUG_ON(rb_first(&cfqq->sort_list)); |
| 1743 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
| 1744 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| 1745 | |
| 1746 | if (unlikely(cfqd->active_queue == cfqq)) { |
| 1747 | __cfq_slice_expired(cfqd, cfqq, 0); |
| 1748 | cfq_schedule_dispatch(cfqd); |
| 1749 | } |
| 1750 | |
| 1751 | kmem_cache_free(cfq_pool, cfqq); |
| 1752 | } |
| 1753 | |
| 1754 | /* |
| 1755 | * Must always be called with the rcu_read_lock() held |
| 1756 | */ |
| 1757 | static void |
| 1758 | __call_for_each_cic(struct io_context *ioc, |
| 1759 | void (*func)(struct io_context *, struct cfq_io_context *)) |
| 1760 | { |
| 1761 | struct cfq_io_context *cic; |
| 1762 | struct hlist_node *n; |
| 1763 | |
| 1764 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) |
| 1765 | func(ioc, cic); |
| 1766 | } |
| 1767 | |
| 1768 | /* |
| 1769 | * Call func for each cic attached to this ioc. |
| 1770 | */ |
| 1771 | static void |
| 1772 | call_for_each_cic(struct io_context *ioc, |
| 1773 | void (*func)(struct io_context *, struct cfq_io_context *)) |
| 1774 | { |
| 1775 | rcu_read_lock(); |
| 1776 | __call_for_each_cic(ioc, func); |
| 1777 | rcu_read_unlock(); |
| 1778 | } |
| 1779 | |
| 1780 | static void cfq_cic_free_rcu(struct rcu_head *head) |
| 1781 | { |
| 1782 | struct cfq_io_context *cic; |
| 1783 | |
| 1784 | cic = container_of(head, struct cfq_io_context, rcu_head); |
| 1785 | |
| 1786 | kmem_cache_free(cfq_ioc_pool, cic); |
| 1787 | elv_ioc_count_dec(cfq_ioc_count); |
| 1788 | |
| 1789 | if (ioc_gone) { |
| 1790 | /* |
| 1791 | * CFQ scheduler is exiting, grab exit lock and check |
| 1792 | * the pending io context count. If it hits zero, |
| 1793 | * complete ioc_gone and set it back to NULL |
| 1794 | */ |
| 1795 | spin_lock(&ioc_gone_lock); |
| 1796 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
| 1797 | complete(ioc_gone); |
| 1798 | ioc_gone = NULL; |
| 1799 | } |
| 1800 | spin_unlock(&ioc_gone_lock); |
| 1801 | } |
| 1802 | } |
| 1803 | |
| 1804 | static void cfq_cic_free(struct cfq_io_context *cic) |
| 1805 | { |
| 1806 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); |
| 1807 | } |
| 1808 | |
| 1809 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) |
| 1810 | { |
| 1811 | unsigned long flags; |
| 1812 | |
| 1813 | BUG_ON(!cic->dead_key); |
| 1814 | |
| 1815 | spin_lock_irqsave(&ioc->lock, flags); |
| 1816 | radix_tree_delete(&ioc->radix_root, cic->dead_key); |
| 1817 | hlist_del_rcu(&cic->cic_list); |
| 1818 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 1819 | |
| 1820 | cfq_cic_free(cic); |
| 1821 | } |
| 1822 | |
| 1823 | /* |
| 1824 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. |
| 1825 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), |
| 1826 | * and ->trim() which is called with the task lock held |
| 1827 | */ |
| 1828 | static void cfq_free_io_context(struct io_context *ioc) |
| 1829 | { |
| 1830 | /* |
| 1831 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
| 1832 | * so no more cic's are allowed to be linked into this ioc. So it |
| 1833 | * should be ok to iterate over the known list, we will see all cic's |
| 1834 | * since no new ones are added. |
| 1835 | */ |
| 1836 | __call_for_each_cic(ioc, cic_free_func); |
| 1837 | } |
| 1838 | |
| 1839 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 1840 | { |
| 1841 | struct cfq_queue *__cfqq, *next; |
| 1842 | |
| 1843 | if (unlikely(cfqq == cfqd->active_queue)) { |
| 1844 | __cfq_slice_expired(cfqd, cfqq, 0); |
| 1845 | cfq_schedule_dispatch(cfqd); |
| 1846 | } |
| 1847 | |
| 1848 | /* |
| 1849 | * If this queue was scheduled to merge with another queue, be |
| 1850 | * sure to drop the reference taken on that queue (and others in |
| 1851 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. |
| 1852 | */ |
| 1853 | __cfqq = cfqq->new_cfqq; |
| 1854 | while (__cfqq) { |
| 1855 | if (__cfqq == cfqq) { |
| 1856 | WARN(1, "cfqq->new_cfqq loop detected\n"); |
| 1857 | break; |
| 1858 | } |
| 1859 | next = __cfqq->new_cfqq; |
| 1860 | cfq_put_queue(__cfqq); |
| 1861 | __cfqq = next; |
| 1862 | } |
| 1863 | |
| 1864 | cfq_put_queue(cfqq); |
| 1865 | } |
| 1866 | |
| 1867 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
| 1868 | struct cfq_io_context *cic) |
| 1869 | { |
| 1870 | struct io_context *ioc = cic->ioc; |
| 1871 | |
| 1872 | list_del_init(&cic->queue_list); |
| 1873 | |
| 1874 | /* |
| 1875 | * Make sure key == NULL is seen for dead queues |
| 1876 | */ |
| 1877 | smp_wmb(); |
| 1878 | cic->dead_key = (unsigned long) cic->key; |
| 1879 | cic->key = NULL; |
| 1880 | |
| 1881 | if (ioc->ioc_data == cic) |
| 1882 | rcu_assign_pointer(ioc->ioc_data, NULL); |
| 1883 | |
| 1884 | if (cic->cfqq[BLK_RW_ASYNC]) { |
| 1885 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); |
| 1886 | cic->cfqq[BLK_RW_ASYNC] = NULL; |
| 1887 | } |
| 1888 | |
| 1889 | if (cic->cfqq[BLK_RW_SYNC]) { |
| 1890 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); |
| 1891 | cic->cfqq[BLK_RW_SYNC] = NULL; |
| 1892 | } |
| 1893 | } |
| 1894 | |
| 1895 | static void cfq_exit_single_io_context(struct io_context *ioc, |
| 1896 | struct cfq_io_context *cic) |
| 1897 | { |
| 1898 | struct cfq_data *cfqd = cic->key; |
| 1899 | |
| 1900 | if (cfqd) { |
| 1901 | struct request_queue *q = cfqd->queue; |
| 1902 | unsigned long flags; |
| 1903 | |
| 1904 | spin_lock_irqsave(q->queue_lock, flags); |
| 1905 | |
| 1906 | /* |
| 1907 | * Ensure we get a fresh copy of the ->key to prevent |
| 1908 | * race between exiting task and queue |
| 1909 | */ |
| 1910 | smp_read_barrier_depends(); |
| 1911 | if (cic->key) |
| 1912 | __cfq_exit_single_io_context(cfqd, cic); |
| 1913 | |
| 1914 | spin_unlock_irqrestore(q->queue_lock, flags); |
| 1915 | } |
| 1916 | } |
| 1917 | |
| 1918 | /* |
| 1919 | * The process that ioc belongs to has exited, we need to clean up |
| 1920 | * and put the internal structures we have that belongs to that process. |
| 1921 | */ |
| 1922 | static void cfq_exit_io_context(struct io_context *ioc) |
| 1923 | { |
| 1924 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
| 1925 | } |
| 1926 | |
| 1927 | static struct cfq_io_context * |
| 1928 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
| 1929 | { |
| 1930 | struct cfq_io_context *cic; |
| 1931 | |
| 1932 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
| 1933 | cfqd->queue->node); |
| 1934 | if (cic) { |
| 1935 | cic->last_end_request = jiffies; |
| 1936 | INIT_LIST_HEAD(&cic->queue_list); |
| 1937 | INIT_HLIST_NODE(&cic->cic_list); |
| 1938 | cic->dtor = cfq_free_io_context; |
| 1939 | cic->exit = cfq_exit_io_context; |
| 1940 | elv_ioc_count_inc(cfq_ioc_count); |
| 1941 | } |
| 1942 | |
| 1943 | return cic; |
| 1944 | } |
| 1945 | |
| 1946 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
| 1947 | { |
| 1948 | struct task_struct *tsk = current; |
| 1949 | int ioprio_class; |
| 1950 | |
| 1951 | if (!cfq_cfqq_prio_changed(cfqq)) |
| 1952 | return; |
| 1953 | |
| 1954 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
| 1955 | switch (ioprio_class) { |
| 1956 | default: |
| 1957 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); |
| 1958 | case IOPRIO_CLASS_NONE: |
| 1959 | /* |
| 1960 | * no prio set, inherit CPU scheduling settings |
| 1961 | */ |
| 1962 | cfqq->ioprio = task_nice_ioprio(tsk); |
| 1963 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
| 1964 | break; |
| 1965 | case IOPRIO_CLASS_RT: |
| 1966 | cfqq->ioprio = task_ioprio(ioc); |
| 1967 | cfqq->ioprio_class = IOPRIO_CLASS_RT; |
| 1968 | break; |
| 1969 | case IOPRIO_CLASS_BE: |
| 1970 | cfqq->ioprio = task_ioprio(ioc); |
| 1971 | cfqq->ioprio_class = IOPRIO_CLASS_BE; |
| 1972 | break; |
| 1973 | case IOPRIO_CLASS_IDLE: |
| 1974 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; |
| 1975 | cfqq->ioprio = 7; |
| 1976 | cfq_clear_cfqq_idle_window(cfqq); |
| 1977 | break; |
| 1978 | } |
| 1979 | |
| 1980 | /* |
| 1981 | * keep track of original prio settings in case we have to temporarily |
| 1982 | * elevate the priority of this queue |
| 1983 | */ |
| 1984 | cfqq->org_ioprio = cfqq->ioprio; |
| 1985 | cfqq->org_ioprio_class = cfqq->ioprio_class; |
| 1986 | cfq_clear_cfqq_prio_changed(cfqq); |
| 1987 | } |
| 1988 | |
| 1989 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
| 1990 | { |
| 1991 | struct cfq_data *cfqd = cic->key; |
| 1992 | struct cfq_queue *cfqq; |
| 1993 | unsigned long flags; |
| 1994 | |
| 1995 | if (unlikely(!cfqd)) |
| 1996 | return; |
| 1997 | |
| 1998 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| 1999 | |
| 2000 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
| 2001 | if (cfqq) { |
| 2002 | struct cfq_queue *new_cfqq; |
| 2003 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
| 2004 | GFP_ATOMIC); |
| 2005 | if (new_cfqq) { |
| 2006 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
| 2007 | cfq_put_queue(cfqq); |
| 2008 | } |
| 2009 | } |
| 2010 | |
| 2011 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
| 2012 | if (cfqq) |
| 2013 | cfq_mark_cfqq_prio_changed(cfqq); |
| 2014 | |
| 2015 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| 2016 | } |
| 2017 | |
| 2018 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
| 2019 | { |
| 2020 | call_for_each_cic(ioc, changed_ioprio); |
| 2021 | ioc->ioprio_changed = 0; |
| 2022 | } |
| 2023 | |
| 2024 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 2025 | pid_t pid, bool is_sync) |
| 2026 | { |
| 2027 | RB_CLEAR_NODE(&cfqq->rb_node); |
| 2028 | RB_CLEAR_NODE(&cfqq->p_node); |
| 2029 | INIT_LIST_HEAD(&cfqq->fifo); |
| 2030 | |
| 2031 | atomic_set(&cfqq->ref, 0); |
| 2032 | cfqq->cfqd = cfqd; |
| 2033 | |
| 2034 | cfq_mark_cfqq_prio_changed(cfqq); |
| 2035 | |
| 2036 | if (is_sync) { |
| 2037 | if (!cfq_class_idle(cfqq)) |
| 2038 | cfq_mark_cfqq_idle_window(cfqq); |
| 2039 | cfq_mark_cfqq_sync(cfqq); |
| 2040 | } |
| 2041 | cfqq->pid = pid; |
| 2042 | } |
| 2043 | |
| 2044 | static struct cfq_queue * |
| 2045 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
| 2046 | struct io_context *ioc, gfp_t gfp_mask) |
| 2047 | { |
| 2048 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
| 2049 | struct cfq_io_context *cic; |
| 2050 | |
| 2051 | retry: |
| 2052 | cic = cfq_cic_lookup(cfqd, ioc); |
| 2053 | /* cic always exists here */ |
| 2054 | cfqq = cic_to_cfqq(cic, is_sync); |
| 2055 | |
| 2056 | /* |
| 2057 | * Always try a new alloc if we fell back to the OOM cfqq |
| 2058 | * originally, since it should just be a temporary situation. |
| 2059 | */ |
| 2060 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
| 2061 | cfqq = NULL; |
| 2062 | if (new_cfqq) { |
| 2063 | cfqq = new_cfqq; |
| 2064 | new_cfqq = NULL; |
| 2065 | } else if (gfp_mask & __GFP_WAIT) { |
| 2066 | spin_unlock_irq(cfqd->queue->queue_lock); |
| 2067 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
| 2068 | gfp_mask | __GFP_ZERO, |
| 2069 | cfqd->queue->node); |
| 2070 | spin_lock_irq(cfqd->queue->queue_lock); |
| 2071 | if (new_cfqq) |
| 2072 | goto retry; |
| 2073 | } else { |
| 2074 | cfqq = kmem_cache_alloc_node(cfq_pool, |
| 2075 | gfp_mask | __GFP_ZERO, |
| 2076 | cfqd->queue->node); |
| 2077 | } |
| 2078 | |
| 2079 | if (cfqq) { |
| 2080 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); |
| 2081 | cfq_init_prio_data(cfqq, ioc); |
| 2082 | cfq_log_cfqq(cfqd, cfqq, "alloced"); |
| 2083 | } else |
| 2084 | cfqq = &cfqd->oom_cfqq; |
| 2085 | } |
| 2086 | |
| 2087 | if (new_cfqq) |
| 2088 | kmem_cache_free(cfq_pool, new_cfqq); |
| 2089 | |
| 2090 | return cfqq; |
| 2091 | } |
| 2092 | |
| 2093 | static struct cfq_queue ** |
| 2094 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) |
| 2095 | { |
| 2096 | switch (ioprio_class) { |
| 2097 | case IOPRIO_CLASS_RT: |
| 2098 | return &cfqd->async_cfqq[0][ioprio]; |
| 2099 | case IOPRIO_CLASS_BE: |
| 2100 | return &cfqd->async_cfqq[1][ioprio]; |
| 2101 | case IOPRIO_CLASS_IDLE: |
| 2102 | return &cfqd->async_idle_cfqq; |
| 2103 | default: |
| 2104 | BUG(); |
| 2105 | } |
| 2106 | } |
| 2107 | |
| 2108 | static struct cfq_queue * |
| 2109 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
| 2110 | gfp_t gfp_mask) |
| 2111 | { |
| 2112 | const int ioprio = task_ioprio(ioc); |
| 2113 | const int ioprio_class = task_ioprio_class(ioc); |
| 2114 | struct cfq_queue **async_cfqq = NULL; |
| 2115 | struct cfq_queue *cfqq = NULL; |
| 2116 | |
| 2117 | if (!is_sync) { |
| 2118 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); |
| 2119 | cfqq = *async_cfqq; |
| 2120 | } |
| 2121 | |
| 2122 | if (!cfqq) |
| 2123 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
| 2124 | |
| 2125 | /* |
| 2126 | * pin the queue now that it's allocated, scheduler exit will prune it |
| 2127 | */ |
| 2128 | if (!is_sync && !(*async_cfqq)) { |
| 2129 | atomic_inc(&cfqq->ref); |
| 2130 | *async_cfqq = cfqq; |
| 2131 | } |
| 2132 | |
| 2133 | atomic_inc(&cfqq->ref); |
| 2134 | return cfqq; |
| 2135 | } |
| 2136 | |
| 2137 | /* |
| 2138 | * We drop cfq io contexts lazily, so we may find a dead one. |
| 2139 | */ |
| 2140 | static void |
| 2141 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
| 2142 | struct cfq_io_context *cic) |
| 2143 | { |
| 2144 | unsigned long flags; |
| 2145 | |
| 2146 | WARN_ON(!list_empty(&cic->queue_list)); |
| 2147 | |
| 2148 | spin_lock_irqsave(&ioc->lock, flags); |
| 2149 | |
| 2150 | BUG_ON(ioc->ioc_data == cic); |
| 2151 | |
| 2152 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
| 2153 | hlist_del_rcu(&cic->cic_list); |
| 2154 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 2155 | |
| 2156 | cfq_cic_free(cic); |
| 2157 | } |
| 2158 | |
| 2159 | static struct cfq_io_context * |
| 2160 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
| 2161 | { |
| 2162 | struct cfq_io_context *cic; |
| 2163 | unsigned long flags; |
| 2164 | void *k; |
| 2165 | |
| 2166 | if (unlikely(!ioc)) |
| 2167 | return NULL; |
| 2168 | |
| 2169 | rcu_read_lock(); |
| 2170 | |
| 2171 | /* |
| 2172 | * we maintain a last-hit cache, to avoid browsing over the tree |
| 2173 | */ |
| 2174 | cic = rcu_dereference(ioc->ioc_data); |
| 2175 | if (cic && cic->key == cfqd) { |
| 2176 | rcu_read_unlock(); |
| 2177 | return cic; |
| 2178 | } |
| 2179 | |
| 2180 | do { |
| 2181 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
| 2182 | rcu_read_unlock(); |
| 2183 | if (!cic) |
| 2184 | break; |
| 2185 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
| 2186 | k = cic->key; |
| 2187 | if (unlikely(!k)) { |
| 2188 | cfq_drop_dead_cic(cfqd, ioc, cic); |
| 2189 | rcu_read_lock(); |
| 2190 | continue; |
| 2191 | } |
| 2192 | |
| 2193 | spin_lock_irqsave(&ioc->lock, flags); |
| 2194 | rcu_assign_pointer(ioc->ioc_data, cic); |
| 2195 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 2196 | break; |
| 2197 | } while (1); |
| 2198 | |
| 2199 | return cic; |
| 2200 | } |
| 2201 | |
| 2202 | /* |
| 2203 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup |
| 2204 | * the process specific cfq io context when entered from the block layer. |
| 2205 | * Also adds the cic to a per-cfqd list, used when this queue is removed. |
| 2206 | */ |
| 2207 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
| 2208 | struct cfq_io_context *cic, gfp_t gfp_mask) |
| 2209 | { |
| 2210 | unsigned long flags; |
| 2211 | int ret; |
| 2212 | |
| 2213 | ret = radix_tree_preload(gfp_mask); |
| 2214 | if (!ret) { |
| 2215 | cic->ioc = ioc; |
| 2216 | cic->key = cfqd; |
| 2217 | |
| 2218 | spin_lock_irqsave(&ioc->lock, flags); |
| 2219 | ret = radix_tree_insert(&ioc->radix_root, |
| 2220 | (unsigned long) cfqd, cic); |
| 2221 | if (!ret) |
| 2222 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); |
| 2223 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 2224 | |
| 2225 | radix_tree_preload_end(); |
| 2226 | |
| 2227 | if (!ret) { |
| 2228 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| 2229 | list_add(&cic->queue_list, &cfqd->cic_list); |
| 2230 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| 2231 | } |
| 2232 | } |
| 2233 | |
| 2234 | if (ret) |
| 2235 | printk(KERN_ERR "cfq: cic link failed!\n"); |
| 2236 | |
| 2237 | return ret; |
| 2238 | } |
| 2239 | |
| 2240 | /* |
| 2241 | * Setup general io context and cfq io context. There can be several cfq |
| 2242 | * io contexts per general io context, if this process is doing io to more |
| 2243 | * than one device managed by cfq. |
| 2244 | */ |
| 2245 | static struct cfq_io_context * |
| 2246 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
| 2247 | { |
| 2248 | struct io_context *ioc = NULL; |
| 2249 | struct cfq_io_context *cic; |
| 2250 | |
| 2251 | might_sleep_if(gfp_mask & __GFP_WAIT); |
| 2252 | |
| 2253 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
| 2254 | if (!ioc) |
| 2255 | return NULL; |
| 2256 | |
| 2257 | cic = cfq_cic_lookup(cfqd, ioc); |
| 2258 | if (cic) |
| 2259 | goto out; |
| 2260 | |
| 2261 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
| 2262 | if (cic == NULL) |
| 2263 | goto err; |
| 2264 | |
| 2265 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
| 2266 | goto err_free; |
| 2267 | |
| 2268 | out: |
| 2269 | smp_read_barrier_depends(); |
| 2270 | if (unlikely(ioc->ioprio_changed)) |
| 2271 | cfq_ioc_set_ioprio(ioc); |
| 2272 | |
| 2273 | return cic; |
| 2274 | err_free: |
| 2275 | cfq_cic_free(cic); |
| 2276 | err: |
| 2277 | put_io_context(ioc); |
| 2278 | return NULL; |
| 2279 | } |
| 2280 | |
| 2281 | static void |
| 2282 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) |
| 2283 | { |
| 2284 | unsigned long elapsed = jiffies - cic->last_end_request; |
| 2285 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
| 2286 | |
| 2287 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
| 2288 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; |
| 2289 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; |
| 2290 | } |
| 2291 | |
| 2292 | static void |
| 2293 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 2294 | struct request *rq) |
| 2295 | { |
| 2296 | sector_t sdist; |
| 2297 | u64 total; |
| 2298 | |
| 2299 | if (!cfqq->last_request_pos) |
| 2300 | sdist = 0; |
| 2301 | else if (cfqq->last_request_pos < blk_rq_pos(rq)) |
| 2302 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; |
| 2303 | else |
| 2304 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
| 2305 | |
| 2306 | /* |
| 2307 | * Don't allow the seek distance to get too large from the |
| 2308 | * odd fragment, pagein, etc |
| 2309 | */ |
| 2310 | if (cfqq->seek_samples <= 60) /* second&third seek */ |
| 2311 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024); |
| 2312 | else |
| 2313 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64); |
| 2314 | |
| 2315 | cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8; |
| 2316 | cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8; |
| 2317 | total = cfqq->seek_total + (cfqq->seek_samples/2); |
| 2318 | do_div(total, cfqq->seek_samples); |
| 2319 | cfqq->seek_mean = (sector_t)total; |
| 2320 | |
| 2321 | /* |
| 2322 | * If this cfqq is shared between multiple processes, check to |
| 2323 | * make sure that those processes are still issuing I/Os within |
| 2324 | * the mean seek distance. If not, it may be time to break the |
| 2325 | * queues apart again. |
| 2326 | */ |
| 2327 | if (cfq_cfqq_coop(cfqq)) { |
| 2328 | if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start) |
| 2329 | cfqq->seeky_start = jiffies; |
| 2330 | else if (!CFQQ_SEEKY(cfqq)) |
| 2331 | cfqq->seeky_start = 0; |
| 2332 | } |
| 2333 | } |
| 2334 | |
| 2335 | /* |
| 2336 | * Disable idle window if the process thinks too long or seeks so much that |
| 2337 | * it doesn't matter |
| 2338 | */ |
| 2339 | static void |
| 2340 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 2341 | struct cfq_io_context *cic) |
| 2342 | { |
| 2343 | int old_idle, enable_idle; |
| 2344 | |
| 2345 | /* |
| 2346 | * Don't idle for async or idle io prio class |
| 2347 | */ |
| 2348 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) |
| 2349 | return; |
| 2350 | |
| 2351 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
| 2352 | |
| 2353 | if (cfqq->queued[0] + cfqq->queued[1] >= 4) |
| 2354 | cfq_mark_cfqq_deep(cfqq); |
| 2355 | |
| 2356 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
| 2357 | (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples) |
| 2358 | && CFQQ_SEEKY(cfqq))) |
| 2359 | enable_idle = 0; |
| 2360 | else if (sample_valid(cic->ttime_samples)) { |
| 2361 | if (cic->ttime_mean > cfqd->cfq_slice_idle) |
| 2362 | enable_idle = 0; |
| 2363 | else |
| 2364 | enable_idle = 1; |
| 2365 | } |
| 2366 | |
| 2367 | if (old_idle != enable_idle) { |
| 2368 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); |
| 2369 | if (enable_idle) |
| 2370 | cfq_mark_cfqq_idle_window(cfqq); |
| 2371 | else |
| 2372 | cfq_clear_cfqq_idle_window(cfqq); |
| 2373 | } |
| 2374 | } |
| 2375 | |
| 2376 | /* |
| 2377 | * Check if new_cfqq should preempt the currently active queue. Return 0 for |
| 2378 | * no or if we aren't sure, a 1 will cause a preempt. |
| 2379 | */ |
| 2380 | static bool |
| 2381 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
| 2382 | struct request *rq) |
| 2383 | { |
| 2384 | struct cfq_queue *cfqq; |
| 2385 | |
| 2386 | cfqq = cfqd->active_queue; |
| 2387 | if (!cfqq) |
| 2388 | return false; |
| 2389 | |
| 2390 | if (cfq_slice_used(cfqq)) |
| 2391 | return true; |
| 2392 | |
| 2393 | if (cfq_class_idle(new_cfqq)) |
| 2394 | return false; |
| 2395 | |
| 2396 | if (cfq_class_idle(cfqq)) |
| 2397 | return true; |
| 2398 | |
| 2399 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && |
| 2400 | cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && |
| 2401 | new_cfqq->service_tree->count == 1) |
| 2402 | return true; |
| 2403 | |
| 2404 | /* |
| 2405 | * if the new request is sync, but the currently running queue is |
| 2406 | * not, let the sync request have priority. |
| 2407 | */ |
| 2408 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
| 2409 | return true; |
| 2410 | |
| 2411 | /* |
| 2412 | * So both queues are sync. Let the new request get disk time if |
| 2413 | * it's a metadata request and the current queue is doing regular IO. |
| 2414 | */ |
| 2415 | if (rq_is_meta(rq) && !cfqq->meta_pending) |
| 2416 | return true; |
| 2417 | |
| 2418 | /* |
| 2419 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. |
| 2420 | */ |
| 2421 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) |
| 2422 | return true; |
| 2423 | |
| 2424 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
| 2425 | return false; |
| 2426 | |
| 2427 | /* |
| 2428 | * if this request is as-good as one we would expect from the |
| 2429 | * current cfqq, let it preempt |
| 2430 | */ |
| 2431 | if (cfq_rq_close(cfqd, cfqq, rq)) |
| 2432 | return true; |
| 2433 | |
| 2434 | return false; |
| 2435 | } |
| 2436 | |
| 2437 | /* |
| 2438 | * cfqq preempts the active queue. if we allowed preempt with no slice left, |
| 2439 | * let it have half of its nominal slice. |
| 2440 | */ |
| 2441 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| 2442 | { |
| 2443 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
| 2444 | cfq_slice_expired(cfqd, 1); |
| 2445 | |
| 2446 | /* |
| 2447 | * Put the new queue at the front of the of the current list, |
| 2448 | * so we know that it will be selected next. |
| 2449 | */ |
| 2450 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| 2451 | |
| 2452 | cfq_service_tree_add(cfqd, cfqq, 1); |
| 2453 | |
| 2454 | cfqq->slice_end = 0; |
| 2455 | cfq_mark_cfqq_slice_new(cfqq); |
| 2456 | } |
| 2457 | |
| 2458 | /* |
| 2459 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
| 2460 | * something we should do about it |
| 2461 | */ |
| 2462 | static void |
| 2463 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| 2464 | struct request *rq) |
| 2465 | { |
| 2466 | struct cfq_io_context *cic = RQ_CIC(rq); |
| 2467 | |
| 2468 | cfqd->rq_queued++; |
| 2469 | if (rq_is_meta(rq)) |
| 2470 | cfqq->meta_pending++; |
| 2471 | |
| 2472 | cfq_update_io_thinktime(cfqd, cic); |
| 2473 | cfq_update_io_seektime(cfqd, cfqq, rq); |
| 2474 | cfq_update_idle_window(cfqd, cfqq, cic); |
| 2475 | |
| 2476 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| 2477 | |
| 2478 | if (cfqq == cfqd->active_queue) { |
| 2479 | /* |
| 2480 | * Remember that we saw a request from this process, but |
| 2481 | * don't start queuing just yet. Otherwise we risk seeing lots |
| 2482 | * of tiny requests, because we disrupt the normal plugging |
| 2483 | * and merging. If the request is already larger than a single |
| 2484 | * page, let it rip immediately. For that case we assume that |
| 2485 | * merging is already done. Ditto for a busy system that |
| 2486 | * has other work pending, don't risk delaying until the |
| 2487 | * idle timer unplug to continue working. |
| 2488 | */ |
| 2489 | if (cfq_cfqq_wait_request(cfqq)) { |
| 2490 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
| 2491 | cfqd->busy_queues > 1) { |
| 2492 | del_timer(&cfqd->idle_slice_timer); |
| 2493 | __blk_run_queue(cfqd->queue); |
| 2494 | } |
| 2495 | cfq_mark_cfqq_must_dispatch(cfqq); |
| 2496 | } |
| 2497 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
| 2498 | /* |
| 2499 | * not the active queue - expire current slice if it is |
| 2500 | * idle and has expired it's mean thinktime or this new queue |
| 2501 | * has some old slice time left and is of higher priority or |
| 2502 | * this new queue is RT and the current one is BE |
| 2503 | */ |
| 2504 | cfq_preempt_queue(cfqd, cfqq); |
| 2505 | __blk_run_queue(cfqd->queue); |
| 2506 | } |
| 2507 | } |
| 2508 | |
| 2509 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
| 2510 | { |
| 2511 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 2512 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 2513 | |
| 2514 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
| 2515 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
| 2516 | |
| 2517 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
| 2518 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
| 2519 | cfq_add_rq_rb(rq); |
| 2520 | |
| 2521 | cfq_rq_enqueued(cfqd, cfqq, rq); |
| 2522 | } |
| 2523 | |
| 2524 | /* |
| 2525 | * Update hw_tag based on peak queue depth over 50 samples under |
| 2526 | * sufficient load. |
| 2527 | */ |
| 2528 | static void cfq_update_hw_tag(struct cfq_data *cfqd) |
| 2529 | { |
| 2530 | struct cfq_queue *cfqq = cfqd->active_queue; |
| 2531 | |
| 2532 | if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth) |
| 2533 | cfqd->hw_tag_est_depth = rq_in_driver(cfqd); |
| 2534 | |
| 2535 | if (cfqd->hw_tag == 1) |
| 2536 | return; |
| 2537 | |
| 2538 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && |
| 2539 | rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
| 2540 | return; |
| 2541 | |
| 2542 | /* |
| 2543 | * If active queue hasn't enough requests and can idle, cfq might not |
| 2544 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this |
| 2545 | * case |
| 2546 | */ |
| 2547 | if (cfqq && cfq_cfqq_idle_window(cfqq) && |
| 2548 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < |
| 2549 | CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN) |
| 2550 | return; |
| 2551 | |
| 2552 | if (cfqd->hw_tag_samples++ < 50) |
| 2553 | return; |
| 2554 | |
| 2555 | if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) |
| 2556 | cfqd->hw_tag = 1; |
| 2557 | else |
| 2558 | cfqd->hw_tag = 0; |
| 2559 | } |
| 2560 | |
| 2561 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
| 2562 | { |
| 2563 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 2564 | struct cfq_data *cfqd = cfqq->cfqd; |
| 2565 | const int sync = rq_is_sync(rq); |
| 2566 | unsigned long now; |
| 2567 | |
| 2568 | now = jiffies; |
| 2569 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
| 2570 | |
| 2571 | cfq_update_hw_tag(cfqd); |
| 2572 | |
| 2573 | WARN_ON(!cfqd->rq_in_driver[sync]); |
| 2574 | WARN_ON(!cfqq->dispatched); |
| 2575 | cfqd->rq_in_driver[sync]--; |
| 2576 | cfqq->dispatched--; |
| 2577 | |
| 2578 | if (cfq_cfqq_sync(cfqq)) |
| 2579 | cfqd->sync_flight--; |
| 2580 | |
| 2581 | if (sync) { |
| 2582 | RQ_CIC(rq)->last_end_request = now; |
| 2583 | cfqd->last_end_sync_rq = now; |
| 2584 | } |
| 2585 | |
| 2586 | /* |
| 2587 | * If this is the active queue, check if it needs to be expired, |
| 2588 | * or if we want to idle in case it has no pending requests. |
| 2589 | */ |
| 2590 | if (cfqd->active_queue == cfqq) { |
| 2591 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
| 2592 | |
| 2593 | if (cfq_cfqq_slice_new(cfqq)) { |
| 2594 | cfq_set_prio_slice(cfqd, cfqq); |
| 2595 | cfq_clear_cfqq_slice_new(cfqq); |
| 2596 | } |
| 2597 | /* |
| 2598 | * Idling is not enabled on: |
| 2599 | * - expired queues |
| 2600 | * - idle-priority queues |
| 2601 | * - async queues |
| 2602 | * - queues with still some requests queued |
| 2603 | * - when there is a close cooperator |
| 2604 | */ |
| 2605 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
| 2606 | cfq_slice_expired(cfqd, 1); |
| 2607 | else if (sync && cfqq_empty && |
| 2608 | !cfq_close_cooperator(cfqd, cfqq)) { |
| 2609 | cfqd->noidle_tree_requires_idle |= !rq_noidle(rq); |
| 2610 | /* |
| 2611 | * Idling is enabled for SYNC_WORKLOAD. |
| 2612 | * SYNC_NOIDLE_WORKLOAD idles at the end of the tree |
| 2613 | * only if we processed at least one !rq_noidle request |
| 2614 | */ |
| 2615 | if (cfqd->serving_type == SYNC_WORKLOAD |
| 2616 | || cfqd->noidle_tree_requires_idle) |
| 2617 | cfq_arm_slice_timer(cfqd); |
| 2618 | } |
| 2619 | } |
| 2620 | |
| 2621 | if (!rq_in_driver(cfqd)) |
| 2622 | cfq_schedule_dispatch(cfqd); |
| 2623 | } |
| 2624 | |
| 2625 | /* |
| 2626 | * we temporarily boost lower priority queues if they are holding fs exclusive |
| 2627 | * resources. they are boosted to normal prio (CLASS_BE/4) |
| 2628 | */ |
| 2629 | static void cfq_prio_boost(struct cfq_queue *cfqq) |
| 2630 | { |
| 2631 | if (has_fs_excl()) { |
| 2632 | /* |
| 2633 | * boost idle prio on transactions that would lock out other |
| 2634 | * users of the filesystem |
| 2635 | */ |
| 2636 | if (cfq_class_idle(cfqq)) |
| 2637 | cfqq->ioprio_class = IOPRIO_CLASS_BE; |
| 2638 | if (cfqq->ioprio > IOPRIO_NORM) |
| 2639 | cfqq->ioprio = IOPRIO_NORM; |
| 2640 | } else { |
| 2641 | /* |
| 2642 | * unboost the queue (if needed) |
| 2643 | */ |
| 2644 | cfqq->ioprio_class = cfqq->org_ioprio_class; |
| 2645 | cfqq->ioprio = cfqq->org_ioprio; |
| 2646 | } |
| 2647 | } |
| 2648 | |
| 2649 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
| 2650 | { |
| 2651 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
| 2652 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
| 2653 | return ELV_MQUEUE_MUST; |
| 2654 | } |
| 2655 | |
| 2656 | return ELV_MQUEUE_MAY; |
| 2657 | } |
| 2658 | |
| 2659 | static int cfq_may_queue(struct request_queue *q, int rw) |
| 2660 | { |
| 2661 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 2662 | struct task_struct *tsk = current; |
| 2663 | struct cfq_io_context *cic; |
| 2664 | struct cfq_queue *cfqq; |
| 2665 | |
| 2666 | /* |
| 2667 | * don't force setup of a queue from here, as a call to may_queue |
| 2668 | * does not necessarily imply that a request actually will be queued. |
| 2669 | * so just lookup a possibly existing queue, or return 'may queue' |
| 2670 | * if that fails |
| 2671 | */ |
| 2672 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
| 2673 | if (!cic) |
| 2674 | return ELV_MQUEUE_MAY; |
| 2675 | |
| 2676 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
| 2677 | if (cfqq) { |
| 2678 | cfq_init_prio_data(cfqq, cic->ioc); |
| 2679 | cfq_prio_boost(cfqq); |
| 2680 | |
| 2681 | return __cfq_may_queue(cfqq); |
| 2682 | } |
| 2683 | |
| 2684 | return ELV_MQUEUE_MAY; |
| 2685 | } |
| 2686 | |
| 2687 | /* |
| 2688 | * queue lock held here |
| 2689 | */ |
| 2690 | static void cfq_put_request(struct request *rq) |
| 2691 | { |
| 2692 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| 2693 | |
| 2694 | if (cfqq) { |
| 2695 | const int rw = rq_data_dir(rq); |
| 2696 | |
| 2697 | BUG_ON(!cfqq->allocated[rw]); |
| 2698 | cfqq->allocated[rw]--; |
| 2699 | |
| 2700 | put_io_context(RQ_CIC(rq)->ioc); |
| 2701 | |
| 2702 | rq->elevator_private = NULL; |
| 2703 | rq->elevator_private2 = NULL; |
| 2704 | |
| 2705 | cfq_put_queue(cfqq); |
| 2706 | } |
| 2707 | } |
| 2708 | |
| 2709 | static struct cfq_queue * |
| 2710 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, |
| 2711 | struct cfq_queue *cfqq) |
| 2712 | { |
| 2713 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); |
| 2714 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); |
| 2715 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
| 2716 | cfq_put_queue(cfqq); |
| 2717 | return cic_to_cfqq(cic, 1); |
| 2718 | } |
| 2719 | |
| 2720 | static int should_split_cfqq(struct cfq_queue *cfqq) |
| 2721 | { |
| 2722 | if (cfqq->seeky_start && |
| 2723 | time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT)) |
| 2724 | return 1; |
| 2725 | return 0; |
| 2726 | } |
| 2727 | |
| 2728 | /* |
| 2729 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this |
| 2730 | * was the last process referring to said cfqq. |
| 2731 | */ |
| 2732 | static struct cfq_queue * |
| 2733 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) |
| 2734 | { |
| 2735 | if (cfqq_process_refs(cfqq) == 1) { |
| 2736 | cfqq->seeky_start = 0; |
| 2737 | cfqq->pid = current->pid; |
| 2738 | cfq_clear_cfqq_coop(cfqq); |
| 2739 | return cfqq; |
| 2740 | } |
| 2741 | |
| 2742 | cic_set_cfqq(cic, NULL, 1); |
| 2743 | cfq_put_queue(cfqq); |
| 2744 | return NULL; |
| 2745 | } |
| 2746 | /* |
| 2747 | * Allocate cfq data structures associated with this request. |
| 2748 | */ |
| 2749 | static int |
| 2750 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
| 2751 | { |
| 2752 | struct cfq_data *cfqd = q->elevator->elevator_data; |
| 2753 | struct cfq_io_context *cic; |
| 2754 | const int rw = rq_data_dir(rq); |
| 2755 | const bool is_sync = rq_is_sync(rq); |
| 2756 | struct cfq_queue *cfqq; |
| 2757 | unsigned long flags; |
| 2758 | |
| 2759 | might_sleep_if(gfp_mask & __GFP_WAIT); |
| 2760 | |
| 2761 | cic = cfq_get_io_context(cfqd, gfp_mask); |
| 2762 | |
| 2763 | spin_lock_irqsave(q->queue_lock, flags); |
| 2764 | |
| 2765 | if (!cic) |
| 2766 | goto queue_fail; |
| 2767 | |
| 2768 | new_queue: |
| 2769 | cfqq = cic_to_cfqq(cic, is_sync); |
| 2770 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
| 2771 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
| 2772 | cic_set_cfqq(cic, cfqq, is_sync); |
| 2773 | } else { |
| 2774 | /* |
| 2775 | * If the queue was seeky for too long, break it apart. |
| 2776 | */ |
| 2777 | if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) { |
| 2778 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); |
| 2779 | cfqq = split_cfqq(cic, cfqq); |
| 2780 | if (!cfqq) |
| 2781 | goto new_queue; |
| 2782 | } |
| 2783 | |
| 2784 | /* |
| 2785 | * Check to see if this queue is scheduled to merge with |
| 2786 | * another, closely cooperating queue. The merging of |
| 2787 | * queues happens here as it must be done in process context. |
| 2788 | * The reference on new_cfqq was taken in merge_cfqqs. |
| 2789 | */ |
| 2790 | if (cfqq->new_cfqq) |
| 2791 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); |
| 2792 | } |
| 2793 | |
| 2794 | cfqq->allocated[rw]++; |
| 2795 | atomic_inc(&cfqq->ref); |
| 2796 | |
| 2797 | spin_unlock_irqrestore(q->queue_lock, flags); |
| 2798 | |
| 2799 | rq->elevator_private = cic; |
| 2800 | rq->elevator_private2 = cfqq; |
| 2801 | return 0; |
| 2802 | |
| 2803 | queue_fail: |
| 2804 | if (cic) |
| 2805 | put_io_context(cic->ioc); |
| 2806 | |
| 2807 | cfq_schedule_dispatch(cfqd); |
| 2808 | spin_unlock_irqrestore(q->queue_lock, flags); |
| 2809 | cfq_log(cfqd, "set_request fail"); |
| 2810 | return 1; |
| 2811 | } |
| 2812 | |
| 2813 | static void cfq_kick_queue(struct work_struct *work) |
| 2814 | { |
| 2815 | struct cfq_data *cfqd = |
| 2816 | container_of(work, struct cfq_data, unplug_work); |
| 2817 | struct request_queue *q = cfqd->queue; |
| 2818 | |
| 2819 | spin_lock_irq(q->queue_lock); |
| 2820 | __blk_run_queue(cfqd->queue); |
| 2821 | spin_unlock_irq(q->queue_lock); |
| 2822 | } |
| 2823 | |
| 2824 | /* |
| 2825 | * Timer running if the active_queue is currently idling inside its time slice |
| 2826 | */ |
| 2827 | static void cfq_idle_slice_timer(unsigned long data) |
| 2828 | { |
| 2829 | struct cfq_data *cfqd = (struct cfq_data *) data; |
| 2830 | struct cfq_queue *cfqq; |
| 2831 | unsigned long flags; |
| 2832 | int timed_out = 1; |
| 2833 | |
| 2834 | cfq_log(cfqd, "idle timer fired"); |
| 2835 | |
| 2836 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| 2837 | |
| 2838 | cfqq = cfqd->active_queue; |
| 2839 | if (cfqq) { |
| 2840 | timed_out = 0; |
| 2841 | |
| 2842 | /* |
| 2843 | * We saw a request before the queue expired, let it through |
| 2844 | */ |
| 2845 | if (cfq_cfqq_must_dispatch(cfqq)) |
| 2846 | goto out_kick; |
| 2847 | |
| 2848 | /* |
| 2849 | * expired |
| 2850 | */ |
| 2851 | if (cfq_slice_used(cfqq)) |
| 2852 | goto expire; |
| 2853 | |
| 2854 | /* |
| 2855 | * only expire and reinvoke request handler, if there are |
| 2856 | * other queues with pending requests |
| 2857 | */ |
| 2858 | if (!cfqd->busy_queues) |
| 2859 | goto out_cont; |
| 2860 | |
| 2861 | /* |
| 2862 | * not expired and it has a request pending, let it dispatch |
| 2863 | */ |
| 2864 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
| 2865 | goto out_kick; |
| 2866 | |
| 2867 | /* |
| 2868 | * Queue depth flag is reset only when the idle didn't succeed |
| 2869 | */ |
| 2870 | cfq_clear_cfqq_deep(cfqq); |
| 2871 | } |
| 2872 | expire: |
| 2873 | cfq_slice_expired(cfqd, timed_out); |
| 2874 | out_kick: |
| 2875 | cfq_schedule_dispatch(cfqd); |
| 2876 | out_cont: |
| 2877 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| 2878 | } |
| 2879 | |
| 2880 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
| 2881 | { |
| 2882 | del_timer_sync(&cfqd->idle_slice_timer); |
| 2883 | cancel_work_sync(&cfqd->unplug_work); |
| 2884 | } |
| 2885 | |
| 2886 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
| 2887 | { |
| 2888 | int i; |
| 2889 | |
| 2890 | for (i = 0; i < IOPRIO_BE_NR; i++) { |
| 2891 | if (cfqd->async_cfqq[0][i]) |
| 2892 | cfq_put_queue(cfqd->async_cfqq[0][i]); |
| 2893 | if (cfqd->async_cfqq[1][i]) |
| 2894 | cfq_put_queue(cfqd->async_cfqq[1][i]); |
| 2895 | } |
| 2896 | |
| 2897 | if (cfqd->async_idle_cfqq) |
| 2898 | cfq_put_queue(cfqd->async_idle_cfqq); |
| 2899 | } |
| 2900 | |
| 2901 | static void cfq_exit_queue(struct elevator_queue *e) |
| 2902 | { |
| 2903 | struct cfq_data *cfqd = e->elevator_data; |
| 2904 | struct request_queue *q = cfqd->queue; |
| 2905 | |
| 2906 | cfq_shutdown_timer_wq(cfqd); |
| 2907 | |
| 2908 | spin_lock_irq(q->queue_lock); |
| 2909 | |
| 2910 | if (cfqd->active_queue) |
| 2911 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
| 2912 | |
| 2913 | while (!list_empty(&cfqd->cic_list)) { |
| 2914 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
| 2915 | struct cfq_io_context, |
| 2916 | queue_list); |
| 2917 | |
| 2918 | __cfq_exit_single_io_context(cfqd, cic); |
| 2919 | } |
| 2920 | |
| 2921 | cfq_put_async_queues(cfqd); |
| 2922 | |
| 2923 | spin_unlock_irq(q->queue_lock); |
| 2924 | |
| 2925 | cfq_shutdown_timer_wq(cfqd); |
| 2926 | |
| 2927 | kfree(cfqd); |
| 2928 | } |
| 2929 | |
| 2930 | static void *cfq_init_queue(struct request_queue *q) |
| 2931 | { |
| 2932 | struct cfq_data *cfqd; |
| 2933 | int i, j; |
| 2934 | |
| 2935 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
| 2936 | if (!cfqd) |
| 2937 | return NULL; |
| 2938 | |
| 2939 | for (i = 0; i < 2; ++i) |
| 2940 | for (j = 0; j < 3; ++j) |
| 2941 | cfqd->service_trees[i][j] = CFQ_RB_ROOT; |
| 2942 | cfqd->service_tree_idle = CFQ_RB_ROOT; |
| 2943 | |
| 2944 | /* |
| 2945 | * Not strictly needed (since RB_ROOT just clears the node and we |
| 2946 | * zeroed cfqd on alloc), but better be safe in case someone decides |
| 2947 | * to add magic to the rb code |
| 2948 | */ |
| 2949 | for (i = 0; i < CFQ_PRIO_LISTS; i++) |
| 2950 | cfqd->prio_trees[i] = RB_ROOT; |
| 2951 | |
| 2952 | /* |
| 2953 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. |
| 2954 | * Grab a permanent reference to it, so that the normal code flow |
| 2955 | * will not attempt to free it. |
| 2956 | */ |
| 2957 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); |
| 2958 | atomic_inc(&cfqd->oom_cfqq.ref); |
| 2959 | |
| 2960 | INIT_LIST_HEAD(&cfqd->cic_list); |
| 2961 | |
| 2962 | cfqd->queue = q; |
| 2963 | |
| 2964 | init_timer(&cfqd->idle_slice_timer); |
| 2965 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; |
| 2966 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; |
| 2967 | |
| 2968 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
| 2969 | |
| 2970 | cfqd->cfq_quantum = cfq_quantum; |
| 2971 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
| 2972 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; |
| 2973 | cfqd->cfq_back_max = cfq_back_max; |
| 2974 | cfqd->cfq_back_penalty = cfq_back_penalty; |
| 2975 | cfqd->cfq_slice[0] = cfq_slice_async; |
| 2976 | cfqd->cfq_slice[1] = cfq_slice_sync; |
| 2977 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; |
| 2978 | cfqd->cfq_slice_idle = cfq_slice_idle; |
| 2979 | cfqd->cfq_latency = 1; |
| 2980 | cfqd->hw_tag = -1; |
| 2981 | cfqd->last_end_sync_rq = jiffies; |
| 2982 | return cfqd; |
| 2983 | } |
| 2984 | |
| 2985 | static void cfq_slab_kill(void) |
| 2986 | { |
| 2987 | /* |
| 2988 | * Caller already ensured that pending RCU callbacks are completed, |
| 2989 | * so we should have no busy allocations at this point. |
| 2990 | */ |
| 2991 | if (cfq_pool) |
| 2992 | kmem_cache_destroy(cfq_pool); |
| 2993 | if (cfq_ioc_pool) |
| 2994 | kmem_cache_destroy(cfq_ioc_pool); |
| 2995 | } |
| 2996 | |
| 2997 | static int __init cfq_slab_setup(void) |
| 2998 | { |
| 2999 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
| 3000 | if (!cfq_pool) |
| 3001 | goto fail; |
| 3002 | |
| 3003 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
| 3004 | if (!cfq_ioc_pool) |
| 3005 | goto fail; |
| 3006 | |
| 3007 | return 0; |
| 3008 | fail: |
| 3009 | cfq_slab_kill(); |
| 3010 | return -ENOMEM; |
| 3011 | } |
| 3012 | |
| 3013 | /* |
| 3014 | * sysfs parts below --> |
| 3015 | */ |
| 3016 | static ssize_t |
| 3017 | cfq_var_show(unsigned int var, char *page) |
| 3018 | { |
| 3019 | return sprintf(page, "%d\n", var); |
| 3020 | } |
| 3021 | |
| 3022 | static ssize_t |
| 3023 | cfq_var_store(unsigned int *var, const char *page, size_t count) |
| 3024 | { |
| 3025 | char *p = (char *) page; |
| 3026 | |
| 3027 | *var = simple_strtoul(p, &p, 10); |
| 3028 | return count; |
| 3029 | } |
| 3030 | |
| 3031 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
| 3032 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
| 3033 | { \ |
| 3034 | struct cfq_data *cfqd = e->elevator_data; \ |
| 3035 | unsigned int __data = __VAR; \ |
| 3036 | if (__CONV) \ |
| 3037 | __data = jiffies_to_msecs(__data); \ |
| 3038 | return cfq_var_show(__data, (page)); \ |
| 3039 | } |
| 3040 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); |
| 3041 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
| 3042 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); |
| 3043 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
| 3044 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); |
| 3045 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
| 3046 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); |
| 3047 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); |
| 3048 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); |
| 3049 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
| 3050 | #undef SHOW_FUNCTION |
| 3051 | |
| 3052 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ |
| 3053 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
| 3054 | { \ |
| 3055 | struct cfq_data *cfqd = e->elevator_data; \ |
| 3056 | unsigned int __data; \ |
| 3057 | int ret = cfq_var_store(&__data, (page), count); \ |
| 3058 | if (__data < (MIN)) \ |
| 3059 | __data = (MIN); \ |
| 3060 | else if (__data > (MAX)) \ |
| 3061 | __data = (MAX); \ |
| 3062 | if (__CONV) \ |
| 3063 | *(__PTR) = msecs_to_jiffies(__data); \ |
| 3064 | else \ |
| 3065 | *(__PTR) = __data; \ |
| 3066 | return ret; \ |
| 3067 | } |
| 3068 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); |
| 3069 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
| 3070 | UINT_MAX, 1); |
| 3071 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, |
| 3072 | UINT_MAX, 1); |
| 3073 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
| 3074 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
| 3075 | UINT_MAX, 0); |
| 3076 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
| 3077 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); |
| 3078 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); |
| 3079 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
| 3080 | UINT_MAX, 0); |
| 3081 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
| 3082 | #undef STORE_FUNCTION |
| 3083 | |
| 3084 | #define CFQ_ATTR(name) \ |
| 3085 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) |
| 3086 | |
| 3087 | static struct elv_fs_entry cfq_attrs[] = { |
| 3088 | CFQ_ATTR(quantum), |
| 3089 | CFQ_ATTR(fifo_expire_sync), |
| 3090 | CFQ_ATTR(fifo_expire_async), |
| 3091 | CFQ_ATTR(back_seek_max), |
| 3092 | CFQ_ATTR(back_seek_penalty), |
| 3093 | CFQ_ATTR(slice_sync), |
| 3094 | CFQ_ATTR(slice_async), |
| 3095 | CFQ_ATTR(slice_async_rq), |
| 3096 | CFQ_ATTR(slice_idle), |
| 3097 | CFQ_ATTR(low_latency), |
| 3098 | __ATTR_NULL |
| 3099 | }; |
| 3100 | |
| 3101 | static struct elevator_type iosched_cfq = { |
| 3102 | .ops = { |
| 3103 | .elevator_merge_fn = cfq_merge, |
| 3104 | .elevator_merged_fn = cfq_merged_request, |
| 3105 | .elevator_merge_req_fn = cfq_merged_requests, |
| 3106 | .elevator_allow_merge_fn = cfq_allow_merge, |
| 3107 | .elevator_dispatch_fn = cfq_dispatch_requests, |
| 3108 | .elevator_add_req_fn = cfq_insert_request, |
| 3109 | .elevator_activate_req_fn = cfq_activate_request, |
| 3110 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
| 3111 | .elevator_queue_empty_fn = cfq_queue_empty, |
| 3112 | .elevator_completed_req_fn = cfq_completed_request, |
| 3113 | .elevator_former_req_fn = elv_rb_former_request, |
| 3114 | .elevator_latter_req_fn = elv_rb_latter_request, |
| 3115 | .elevator_set_req_fn = cfq_set_request, |
| 3116 | .elevator_put_req_fn = cfq_put_request, |
| 3117 | .elevator_may_queue_fn = cfq_may_queue, |
| 3118 | .elevator_init_fn = cfq_init_queue, |
| 3119 | .elevator_exit_fn = cfq_exit_queue, |
| 3120 | .trim = cfq_free_io_context, |
| 3121 | }, |
| 3122 | .elevator_attrs = cfq_attrs, |
| 3123 | .elevator_name = "cfq", |
| 3124 | .elevator_owner = THIS_MODULE, |
| 3125 | }; |
| 3126 | |
| 3127 | static int __init cfq_init(void) |
| 3128 | { |
| 3129 | /* |
| 3130 | * could be 0 on HZ < 1000 setups |
| 3131 | */ |
| 3132 | if (!cfq_slice_async) |
| 3133 | cfq_slice_async = 1; |
| 3134 | if (!cfq_slice_idle) |
| 3135 | cfq_slice_idle = 1; |
| 3136 | |
| 3137 | if (cfq_slab_setup()) |
| 3138 | return -ENOMEM; |
| 3139 | |
| 3140 | elv_register(&iosched_cfq); |
| 3141 | |
| 3142 | return 0; |
| 3143 | } |
| 3144 | |
| 3145 | static void __exit cfq_exit(void) |
| 3146 | { |
| 3147 | DECLARE_COMPLETION_ONSTACK(all_gone); |
| 3148 | elv_unregister(&iosched_cfq); |
| 3149 | ioc_gone = &all_gone; |
| 3150 | /* ioc_gone's update must be visible before reading ioc_count */ |
| 3151 | smp_wmb(); |
| 3152 | |
| 3153 | /* |
| 3154 | * this also protects us from entering cfq_slab_kill() with |
| 3155 | * pending RCU callbacks |
| 3156 | */ |
| 3157 | if (elv_ioc_count_read(cfq_ioc_count)) |
| 3158 | wait_for_completion(&all_gone); |
| 3159 | cfq_slab_kill(); |
| 3160 | } |
| 3161 | |
| 3162 | module_init(cfq_init); |
| 3163 | module_exit(cfq_exit); |
| 3164 | |
| 3165 | MODULE_AUTHOR("Jens Axboe"); |
| 3166 | MODULE_LICENSE("GPL"); |
| 3167 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |