cfq-iosched.c revision b1ffe737f5b743115ee46ffb59e338e580c54902
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#include "blk-cgroup.h" 17 18/* 19 * tunables 20 */ 21/* max queue in one round of service */ 22static const int cfq_quantum = 8; 23static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 24/* maximum backwards seek, in KiB */ 25static const int cfq_back_max = 16 * 1024; 26/* penalty of a backwards seek */ 27static const int cfq_back_penalty = 2; 28static const int cfq_slice_sync = HZ / 10; 29static int cfq_slice_async = HZ / 25; 30static const int cfq_slice_async_rq = 2; 31static int cfq_slice_idle = HZ / 125; 32static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 33static const int cfq_hist_divisor = 4; 34 35/* 36 * offset from end of service tree 37 */ 38#define CFQ_IDLE_DELAY (HZ / 5) 39 40/* 41 * below this threshold, we consider thinktime immediate 42 */ 43#define CFQ_MIN_TT (2) 44 45#define CFQ_SLICE_SCALE (5) 46#define CFQ_HW_QUEUE_MIN (5) 47#define CFQ_SERVICE_SHIFT 12 48 49#define CFQQ_SEEK_THR (sector_t)(8 * 100) 50#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 51#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 52#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 53 54#define RQ_CIC(rq) \ 55 ((struct cfq_io_context *) (rq)->elevator_private) 56#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) 57 58static struct kmem_cache *cfq_pool; 59static struct kmem_cache *cfq_ioc_pool; 60 61static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); 62static struct completion *ioc_gone; 63static DEFINE_SPINLOCK(ioc_gone_lock); 64 65#define CFQ_PRIO_LISTS IOPRIO_BE_NR 66#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 67#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 68 69#define sample_valid(samples) ((samples) > 80) 70#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 71 72/* 73 * Most of our rbtree usage is for sorting with min extraction, so 74 * if we cache the leftmost node we don't have to walk down the tree 75 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 76 * move this into the elevator for the rq sorting as well. 77 */ 78struct cfq_rb_root { 79 struct rb_root rb; 80 struct rb_node *left; 81 unsigned count; 82 unsigned total_weight; 83 u64 min_vdisktime; 84 struct rb_node *active; 85}; 86#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ 87 .count = 0, .min_vdisktime = 0, } 88 89/* 90 * Per process-grouping structure 91 */ 92struct cfq_queue { 93 /* reference count */ 94 atomic_t ref; 95 /* various state flags, see below */ 96 unsigned int flags; 97 /* parent cfq_data */ 98 struct cfq_data *cfqd; 99 /* service_tree member */ 100 struct rb_node rb_node; 101 /* service_tree key */ 102 unsigned long rb_key; 103 /* prio tree member */ 104 struct rb_node p_node; 105 /* prio tree root we belong to, if any */ 106 struct rb_root *p_root; 107 /* sorted list of pending requests */ 108 struct rb_root sort_list; 109 /* if fifo isn't expired, next request to serve */ 110 struct request *next_rq; 111 /* requests queued in sort_list */ 112 int queued[2]; 113 /* currently allocated requests */ 114 int allocated[2]; 115 /* fifo list of requests in sort_list */ 116 struct list_head fifo; 117 118 /* time when queue got scheduled in to dispatch first request. */ 119 unsigned long dispatch_start; 120 unsigned int allocated_slice; 121 unsigned int slice_dispatch; 122 /* time when first request from queue completed and slice started. */ 123 unsigned long slice_start; 124 unsigned long slice_end; 125 long slice_resid; 126 127 /* pending metadata requests */ 128 int meta_pending; 129 /* number of requests that are on the dispatch list or inside driver */ 130 int dispatched; 131 132 /* io prio of this group */ 133 unsigned short ioprio, org_ioprio; 134 unsigned short ioprio_class, org_ioprio_class; 135 136 pid_t pid; 137 138 u32 seek_history; 139 sector_t last_request_pos; 140 141 struct cfq_rb_root *service_tree; 142 struct cfq_queue *new_cfqq; 143 struct cfq_group *cfqg; 144 struct cfq_group *orig_cfqg; 145 /* Sectors dispatched in current dispatch round */ 146 unsigned long nr_sectors; 147}; 148 149/* 150 * First index in the service_trees. 151 * IDLE is handled separately, so it has negative index 152 */ 153enum wl_prio_t { 154 BE_WORKLOAD = 0, 155 RT_WORKLOAD = 1, 156 IDLE_WORKLOAD = 2, 157}; 158 159/* 160 * Second index in the service_trees. 161 */ 162enum wl_type_t { 163 ASYNC_WORKLOAD = 0, 164 SYNC_NOIDLE_WORKLOAD = 1, 165 SYNC_WORKLOAD = 2 166}; 167 168/* This is per cgroup per device grouping structure */ 169struct cfq_group { 170 /* group service_tree member */ 171 struct rb_node rb_node; 172 173 /* group service_tree key */ 174 u64 vdisktime; 175 unsigned int weight; 176 bool on_st; 177 178 /* number of cfqq currently on this group */ 179 int nr_cfqq; 180 181 /* Per group busy queus average. Useful for workload slice calc. */ 182 unsigned int busy_queues_avg[2]; 183 /* 184 * rr lists of queues with requests, onle rr for each priority class. 185 * Counts are embedded in the cfq_rb_root 186 */ 187 struct cfq_rb_root service_trees[2][3]; 188 struct cfq_rb_root service_tree_idle; 189 190 unsigned long saved_workload_slice; 191 enum wl_type_t saved_workload; 192 enum wl_prio_t saved_serving_prio; 193 struct blkio_group blkg; 194#ifdef CONFIG_CFQ_GROUP_IOSCHED 195 struct hlist_node cfqd_node; 196 atomic_t ref; 197#endif 198}; 199 200/* 201 * Per block device queue structure 202 */ 203struct cfq_data { 204 struct request_queue *queue; 205 /* Root service tree for cfq_groups */ 206 struct cfq_rb_root grp_service_tree; 207 struct cfq_group root_group; 208 209 /* 210 * The priority currently being served 211 */ 212 enum wl_prio_t serving_prio; 213 enum wl_type_t serving_type; 214 unsigned long workload_expires; 215 struct cfq_group *serving_group; 216 bool noidle_tree_requires_idle; 217 218 /* 219 * Each priority tree is sorted by next_request position. These 220 * trees are used when determining if two or more queues are 221 * interleaving requests (see cfq_close_cooperator). 222 */ 223 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 224 225 unsigned int busy_queues; 226 227 int rq_in_driver; 228 int rq_in_flight[2]; 229 230 /* 231 * queue-depth detection 232 */ 233 int rq_queued; 234 int hw_tag; 235 /* 236 * hw_tag can be 237 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 238 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 239 * 0 => no NCQ 240 */ 241 int hw_tag_est_depth; 242 unsigned int hw_tag_samples; 243 244 /* 245 * idle window management 246 */ 247 struct timer_list idle_slice_timer; 248 struct work_struct unplug_work; 249 250 struct cfq_queue *active_queue; 251 struct cfq_io_context *active_cic; 252 253 /* 254 * async queue for each priority case 255 */ 256 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 257 struct cfq_queue *async_idle_cfqq; 258 259 sector_t last_position; 260 261 /* 262 * tunables, see top of file 263 */ 264 unsigned int cfq_quantum; 265 unsigned int cfq_fifo_expire[2]; 266 unsigned int cfq_back_penalty; 267 unsigned int cfq_back_max; 268 unsigned int cfq_slice[2]; 269 unsigned int cfq_slice_async_rq; 270 unsigned int cfq_slice_idle; 271 unsigned int cfq_latency; 272 unsigned int cfq_group_isolation; 273 274 struct list_head cic_list; 275 276 /* 277 * Fallback dummy cfqq for extreme OOM conditions 278 */ 279 struct cfq_queue oom_cfqq; 280 281 unsigned long last_delayed_sync; 282 283 /* List of cfq groups being managed on this device*/ 284 struct hlist_head cfqg_list; 285 struct rcu_head rcu; 286}; 287 288static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 289 290static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 291 enum wl_prio_t prio, 292 enum wl_type_t type) 293{ 294 if (!cfqg) 295 return NULL; 296 297 if (prio == IDLE_WORKLOAD) 298 return &cfqg->service_tree_idle; 299 300 return &cfqg->service_trees[prio][type]; 301} 302 303enum cfqq_state_flags { 304 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 305 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 306 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 307 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 308 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 309 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 310 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 311 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 312 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 313 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 314 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 315 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 316 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 317}; 318 319#define CFQ_CFQQ_FNS(name) \ 320static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 321{ \ 322 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 323} \ 324static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 325{ \ 326 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 327} \ 328static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 329{ \ 330 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 331} 332 333CFQ_CFQQ_FNS(on_rr); 334CFQ_CFQQ_FNS(wait_request); 335CFQ_CFQQ_FNS(must_dispatch); 336CFQ_CFQQ_FNS(must_alloc_slice); 337CFQ_CFQQ_FNS(fifo_expire); 338CFQ_CFQQ_FNS(idle_window); 339CFQ_CFQQ_FNS(prio_changed); 340CFQ_CFQQ_FNS(slice_new); 341CFQ_CFQQ_FNS(sync); 342CFQ_CFQQ_FNS(coop); 343CFQ_CFQQ_FNS(split_coop); 344CFQ_CFQQ_FNS(deep); 345CFQ_CFQQ_FNS(wait_busy); 346#undef CFQ_CFQQ_FNS 347 348#ifdef CONFIG_DEBUG_CFQ_IOSCHED 349#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 350 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 351 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 352 blkg_path(&(cfqq)->cfqg->blkg), ##args); 353 354#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 355 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 356 blkg_path(&(cfqg)->blkg), ##args); \ 357 358#else 359#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 360 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 361#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0); 362#endif 363#define cfq_log(cfqd, fmt, args...) \ 364 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 365 366/* Traverses through cfq group service trees */ 367#define for_each_cfqg_st(cfqg, i, j, st) \ 368 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 369 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 370 : &cfqg->service_tree_idle; \ 371 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 372 (i == IDLE_WORKLOAD && j == 0); \ 373 j++, st = i < IDLE_WORKLOAD ? \ 374 &cfqg->service_trees[i][j]: NULL) \ 375 376 377static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 378{ 379 if (cfq_class_idle(cfqq)) 380 return IDLE_WORKLOAD; 381 if (cfq_class_rt(cfqq)) 382 return RT_WORKLOAD; 383 return BE_WORKLOAD; 384} 385 386 387static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 388{ 389 if (!cfq_cfqq_sync(cfqq)) 390 return ASYNC_WORKLOAD; 391 if (!cfq_cfqq_idle_window(cfqq)) 392 return SYNC_NOIDLE_WORKLOAD; 393 return SYNC_WORKLOAD; 394} 395 396static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 397 struct cfq_data *cfqd, 398 struct cfq_group *cfqg) 399{ 400 if (wl == IDLE_WORKLOAD) 401 return cfqg->service_tree_idle.count; 402 403 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 404 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 405 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 406} 407 408static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 409 struct cfq_group *cfqg) 410{ 411 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 412 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 413} 414 415static void cfq_dispatch_insert(struct request_queue *, struct request *); 416static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, 417 struct io_context *, gfp_t); 418static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, 419 struct io_context *); 420 421static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, 422 bool is_sync) 423{ 424 return cic->cfqq[is_sync]; 425} 426 427static inline void cic_set_cfqq(struct cfq_io_context *cic, 428 struct cfq_queue *cfqq, bool is_sync) 429{ 430 cic->cfqq[is_sync] = cfqq; 431} 432 433/* 434 * We regard a request as SYNC, if it's either a read or has the SYNC bit 435 * set (in which case it could also be direct WRITE). 436 */ 437static inline bool cfq_bio_sync(struct bio *bio) 438{ 439 return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); 440} 441 442/* 443 * scheduler run of queue, if there are requests pending and no one in the 444 * driver that will restart queueing 445 */ 446static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 447{ 448 if (cfqd->busy_queues) { 449 cfq_log(cfqd, "schedule dispatch"); 450 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 451 } 452} 453 454static int cfq_queue_empty(struct request_queue *q) 455{ 456 struct cfq_data *cfqd = q->elevator->elevator_data; 457 458 return !cfqd->rq_queued; 459} 460 461/* 462 * Scale schedule slice based on io priority. Use the sync time slice only 463 * if a queue is marked sync and has sync io queued. A sync queue with async 464 * io only, should not get full sync slice length. 465 */ 466static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 467 unsigned short prio) 468{ 469 const int base_slice = cfqd->cfq_slice[sync]; 470 471 WARN_ON(prio >= IOPRIO_BE_NR); 472 473 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 474} 475 476static inline int 477cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 478{ 479 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 480} 481 482static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 483{ 484 u64 d = delta << CFQ_SERVICE_SHIFT; 485 486 d = d * BLKIO_WEIGHT_DEFAULT; 487 do_div(d, cfqg->weight); 488 return d; 489} 490 491static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 492{ 493 s64 delta = (s64)(vdisktime - min_vdisktime); 494 if (delta > 0) 495 min_vdisktime = vdisktime; 496 497 return min_vdisktime; 498} 499 500static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 501{ 502 s64 delta = (s64)(vdisktime - min_vdisktime); 503 if (delta < 0) 504 min_vdisktime = vdisktime; 505 506 return min_vdisktime; 507} 508 509static void update_min_vdisktime(struct cfq_rb_root *st) 510{ 511 u64 vdisktime = st->min_vdisktime; 512 struct cfq_group *cfqg; 513 514 if (st->active) { 515 cfqg = rb_entry_cfqg(st->active); 516 vdisktime = cfqg->vdisktime; 517 } 518 519 if (st->left) { 520 cfqg = rb_entry_cfqg(st->left); 521 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime); 522 } 523 524 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime); 525} 526 527/* 528 * get averaged number of queues of RT/BE priority. 529 * average is updated, with a formula that gives more weight to higher numbers, 530 * to quickly follows sudden increases and decrease slowly 531 */ 532 533static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 534 struct cfq_group *cfqg, bool rt) 535{ 536 unsigned min_q, max_q; 537 unsigned mult = cfq_hist_divisor - 1; 538 unsigned round = cfq_hist_divisor / 2; 539 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 540 541 min_q = min(cfqg->busy_queues_avg[rt], busy); 542 max_q = max(cfqg->busy_queues_avg[rt], busy); 543 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 544 cfq_hist_divisor; 545 return cfqg->busy_queues_avg[rt]; 546} 547 548static inline unsigned 549cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 550{ 551 struct cfq_rb_root *st = &cfqd->grp_service_tree; 552 553 return cfq_target_latency * cfqg->weight / st->total_weight; 554} 555 556static inline void 557cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 558{ 559 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 560 if (cfqd->cfq_latency) { 561 /* 562 * interested queues (we consider only the ones with the same 563 * priority class in the cfq group) 564 */ 565 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 566 cfq_class_rt(cfqq)); 567 unsigned sync_slice = cfqd->cfq_slice[1]; 568 unsigned expect_latency = sync_slice * iq; 569 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 570 571 if (expect_latency > group_slice) { 572 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 573 /* scale low_slice according to IO priority 574 * and sync vs async */ 575 unsigned low_slice = 576 min(slice, base_low_slice * slice / sync_slice); 577 /* the adapted slice value is scaled to fit all iqs 578 * into the target latency */ 579 slice = max(slice * group_slice / expect_latency, 580 low_slice); 581 } 582 } 583 cfqq->slice_start = jiffies; 584 cfqq->slice_end = jiffies + slice; 585 cfqq->allocated_slice = slice; 586 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 587} 588 589/* 590 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 591 * isn't valid until the first request from the dispatch is activated 592 * and the slice time set. 593 */ 594static inline bool cfq_slice_used(struct cfq_queue *cfqq) 595{ 596 if (cfq_cfqq_slice_new(cfqq)) 597 return 0; 598 if (time_before(jiffies, cfqq->slice_end)) 599 return 0; 600 601 return 1; 602} 603 604/* 605 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 606 * We choose the request that is closest to the head right now. Distance 607 * behind the head is penalized and only allowed to a certain extent. 608 */ 609static struct request * 610cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 611{ 612 sector_t s1, s2, d1 = 0, d2 = 0; 613 unsigned long back_max; 614#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 615#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 616 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 617 618 if (rq1 == NULL || rq1 == rq2) 619 return rq2; 620 if (rq2 == NULL) 621 return rq1; 622 623 if (rq_is_sync(rq1) && !rq_is_sync(rq2)) 624 return rq1; 625 else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) 626 return rq2; 627 if (rq_is_meta(rq1) && !rq_is_meta(rq2)) 628 return rq1; 629 else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) 630 return rq2; 631 632 s1 = blk_rq_pos(rq1); 633 s2 = blk_rq_pos(rq2); 634 635 /* 636 * by definition, 1KiB is 2 sectors 637 */ 638 back_max = cfqd->cfq_back_max * 2; 639 640 /* 641 * Strict one way elevator _except_ in the case where we allow 642 * short backward seeks which are biased as twice the cost of a 643 * similar forward seek. 644 */ 645 if (s1 >= last) 646 d1 = s1 - last; 647 else if (s1 + back_max >= last) 648 d1 = (last - s1) * cfqd->cfq_back_penalty; 649 else 650 wrap |= CFQ_RQ1_WRAP; 651 652 if (s2 >= last) 653 d2 = s2 - last; 654 else if (s2 + back_max >= last) 655 d2 = (last - s2) * cfqd->cfq_back_penalty; 656 else 657 wrap |= CFQ_RQ2_WRAP; 658 659 /* Found required data */ 660 661 /* 662 * By doing switch() on the bit mask "wrap" we avoid having to 663 * check two variables for all permutations: --> faster! 664 */ 665 switch (wrap) { 666 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 667 if (d1 < d2) 668 return rq1; 669 else if (d2 < d1) 670 return rq2; 671 else { 672 if (s1 >= s2) 673 return rq1; 674 else 675 return rq2; 676 } 677 678 case CFQ_RQ2_WRAP: 679 return rq1; 680 case CFQ_RQ1_WRAP: 681 return rq2; 682 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 683 default: 684 /* 685 * Since both rqs are wrapped, 686 * start with the one that's further behind head 687 * (--> only *one* back seek required), 688 * since back seek takes more time than forward. 689 */ 690 if (s1 <= s2) 691 return rq1; 692 else 693 return rq2; 694 } 695} 696 697/* 698 * The below is leftmost cache rbtree addon 699 */ 700static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 701{ 702 /* Service tree is empty */ 703 if (!root->count) 704 return NULL; 705 706 if (!root->left) 707 root->left = rb_first(&root->rb); 708 709 if (root->left) 710 return rb_entry(root->left, struct cfq_queue, rb_node); 711 712 return NULL; 713} 714 715static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 716{ 717 if (!root->left) 718 root->left = rb_first(&root->rb); 719 720 if (root->left) 721 return rb_entry_cfqg(root->left); 722 723 return NULL; 724} 725 726static void rb_erase_init(struct rb_node *n, struct rb_root *root) 727{ 728 rb_erase(n, root); 729 RB_CLEAR_NODE(n); 730} 731 732static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 733{ 734 if (root->left == n) 735 root->left = NULL; 736 rb_erase_init(n, &root->rb); 737 --root->count; 738} 739 740/* 741 * would be nice to take fifo expire time into account as well 742 */ 743static struct request * 744cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 745 struct request *last) 746{ 747 struct rb_node *rbnext = rb_next(&last->rb_node); 748 struct rb_node *rbprev = rb_prev(&last->rb_node); 749 struct request *next = NULL, *prev = NULL; 750 751 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 752 753 if (rbprev) 754 prev = rb_entry_rq(rbprev); 755 756 if (rbnext) 757 next = rb_entry_rq(rbnext); 758 else { 759 rbnext = rb_first(&cfqq->sort_list); 760 if (rbnext && rbnext != &last->rb_node) 761 next = rb_entry_rq(rbnext); 762 } 763 764 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 765} 766 767static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 768 struct cfq_queue *cfqq) 769{ 770 /* 771 * just an approximation, should be ok. 772 */ 773 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 774 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 775} 776 777static inline s64 778cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 779{ 780 return cfqg->vdisktime - st->min_vdisktime; 781} 782 783static void 784__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 785{ 786 struct rb_node **node = &st->rb.rb_node; 787 struct rb_node *parent = NULL; 788 struct cfq_group *__cfqg; 789 s64 key = cfqg_key(st, cfqg); 790 int left = 1; 791 792 while (*node != NULL) { 793 parent = *node; 794 __cfqg = rb_entry_cfqg(parent); 795 796 if (key < cfqg_key(st, __cfqg)) 797 node = &parent->rb_left; 798 else { 799 node = &parent->rb_right; 800 left = 0; 801 } 802 } 803 804 if (left) 805 st->left = &cfqg->rb_node; 806 807 rb_link_node(&cfqg->rb_node, parent, node); 808 rb_insert_color(&cfqg->rb_node, &st->rb); 809} 810 811static void 812cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 813{ 814 struct cfq_rb_root *st = &cfqd->grp_service_tree; 815 struct cfq_group *__cfqg; 816 struct rb_node *n; 817 818 cfqg->nr_cfqq++; 819 if (cfqg->on_st) 820 return; 821 822 /* 823 * Currently put the group at the end. Later implement something 824 * so that groups get lesser vtime based on their weights, so that 825 * if group does not loose all if it was not continously backlogged. 826 */ 827 n = rb_last(&st->rb); 828 if (n) { 829 __cfqg = rb_entry_cfqg(n); 830 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 831 } else 832 cfqg->vdisktime = st->min_vdisktime; 833 834 __cfq_group_service_tree_add(st, cfqg); 835 cfqg->on_st = true; 836 st->total_weight += cfqg->weight; 837} 838 839static void 840cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 841{ 842 struct cfq_rb_root *st = &cfqd->grp_service_tree; 843 844 if (st->active == &cfqg->rb_node) 845 st->active = NULL; 846 847 BUG_ON(cfqg->nr_cfqq < 1); 848 cfqg->nr_cfqq--; 849 850 /* If there are other cfq queues under this group, don't delete it */ 851 if (cfqg->nr_cfqq) 852 return; 853 854 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 855 cfqg->on_st = false; 856 st->total_weight -= cfqg->weight; 857 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 858 cfq_rb_erase(&cfqg->rb_node, st); 859 cfqg->saved_workload_slice = 0; 860 blkiocg_update_blkio_group_dequeue_stats(&cfqg->blkg, 1); 861} 862 863static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq) 864{ 865 unsigned int slice_used; 866 867 /* 868 * Queue got expired before even a single request completed or 869 * got expired immediately after first request completion. 870 */ 871 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 872 /* 873 * Also charge the seek time incurred to the group, otherwise 874 * if there are mutiple queues in the group, each can dispatch 875 * a single request on seeky media and cause lots of seek time 876 * and group will never know it. 877 */ 878 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 879 1); 880 } else { 881 slice_used = jiffies - cfqq->slice_start; 882 if (slice_used > cfqq->allocated_slice) 883 slice_used = cfqq->allocated_slice; 884 } 885 886 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u sect=%lu", slice_used, 887 cfqq->nr_sectors); 888 return slice_used; 889} 890 891static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 892 struct cfq_queue *cfqq) 893{ 894 struct cfq_rb_root *st = &cfqd->grp_service_tree; 895 unsigned int used_sl, charge_sl; 896 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 897 - cfqg->service_tree_idle.count; 898 899 BUG_ON(nr_sync < 0); 900 used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq); 901 902 if (!cfq_cfqq_sync(cfqq) && !nr_sync) 903 charge_sl = cfqq->allocated_slice; 904 905 /* Can't update vdisktime while group is on service tree */ 906 cfq_rb_erase(&cfqg->rb_node, st); 907 cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg); 908 __cfq_group_service_tree_add(st, cfqg); 909 910 /* This group is being expired. Save the context */ 911 if (time_after(cfqd->workload_expires, jiffies)) { 912 cfqg->saved_workload_slice = cfqd->workload_expires 913 - jiffies; 914 cfqg->saved_workload = cfqd->serving_type; 915 cfqg->saved_serving_prio = cfqd->serving_prio; 916 } else 917 cfqg->saved_workload_slice = 0; 918 919 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 920 st->min_vdisktime); 921 blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl, 922 cfqq->nr_sectors); 923} 924 925#ifdef CONFIG_CFQ_GROUP_IOSCHED 926static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 927{ 928 if (blkg) 929 return container_of(blkg, struct cfq_group, blkg); 930 return NULL; 931} 932 933void 934cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight) 935{ 936 cfqg_of_blkg(blkg)->weight = weight; 937} 938 939static struct cfq_group * 940cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) 941{ 942 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); 943 struct cfq_group *cfqg = NULL; 944 void *key = cfqd; 945 int i, j; 946 struct cfq_rb_root *st; 947 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 948 unsigned int major, minor; 949 950 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); 951 if (cfqg || !create) 952 goto done; 953 954 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 955 if (!cfqg) 956 goto done; 957 958 cfqg->weight = blkcg->weight; 959 for_each_cfqg_st(cfqg, i, j, st) 960 *st = CFQ_RB_ROOT; 961 RB_CLEAR_NODE(&cfqg->rb_node); 962 963 /* 964 * Take the initial reference that will be released on destroy 965 * This can be thought of a joint reference by cgroup and 966 * elevator which will be dropped by either elevator exit 967 * or cgroup deletion path depending on who is exiting first. 968 */ 969 atomic_set(&cfqg->ref, 1); 970 971 /* Add group onto cgroup list */ 972 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 973 blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, 974 MKDEV(major, minor)); 975 976 /* Add group on cfqd list */ 977 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 978 979done: 980 return cfqg; 981} 982 983/* 984 * Search for the cfq group current task belongs to. If create = 1, then also 985 * create the cfq group if it does not exist. request_queue lock must be held. 986 */ 987static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) 988{ 989 struct cgroup *cgroup; 990 struct cfq_group *cfqg = NULL; 991 992 rcu_read_lock(); 993 cgroup = task_cgroup(current, blkio_subsys_id); 994 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create); 995 if (!cfqg && create) 996 cfqg = &cfqd->root_group; 997 rcu_read_unlock(); 998 return cfqg; 999} 1000 1001static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1002{ 1003 /* Currently, all async queues are mapped to root group */ 1004 if (!cfq_cfqq_sync(cfqq)) 1005 cfqg = &cfqq->cfqd->root_group; 1006 1007 cfqq->cfqg = cfqg; 1008 /* cfqq reference on cfqg */ 1009 atomic_inc(&cfqq->cfqg->ref); 1010} 1011 1012static void cfq_put_cfqg(struct cfq_group *cfqg) 1013{ 1014 struct cfq_rb_root *st; 1015 int i, j; 1016 1017 BUG_ON(atomic_read(&cfqg->ref) <= 0); 1018 if (!atomic_dec_and_test(&cfqg->ref)) 1019 return; 1020 for_each_cfqg_st(cfqg, i, j, st) 1021 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL); 1022 kfree(cfqg); 1023} 1024 1025static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1026{ 1027 /* Something wrong if we are trying to remove same group twice */ 1028 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1029 1030 hlist_del_init(&cfqg->cfqd_node); 1031 1032 /* 1033 * Put the reference taken at the time of creation so that when all 1034 * queues are gone, group can be destroyed. 1035 */ 1036 cfq_put_cfqg(cfqg); 1037} 1038 1039static void cfq_release_cfq_groups(struct cfq_data *cfqd) 1040{ 1041 struct hlist_node *pos, *n; 1042 struct cfq_group *cfqg; 1043 1044 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1045 /* 1046 * If cgroup removal path got to blk_group first and removed 1047 * it from cgroup list, then it will take care of destroying 1048 * cfqg also. 1049 */ 1050 if (!blkiocg_del_blkio_group(&cfqg->blkg)) 1051 cfq_destroy_cfqg(cfqd, cfqg); 1052 } 1053} 1054 1055/* 1056 * Blk cgroup controller notification saying that blkio_group object is being 1057 * delinked as associated cgroup object is going away. That also means that 1058 * no new IO will come in this group. So get rid of this group as soon as 1059 * any pending IO in the group is finished. 1060 * 1061 * This function is called under rcu_read_lock(). key is the rcu protected 1062 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu 1063 * read lock. 1064 * 1065 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means 1066 * it should not be NULL as even if elevator was exiting, cgroup deltion 1067 * path got to it first. 1068 */ 1069void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) 1070{ 1071 unsigned long flags; 1072 struct cfq_data *cfqd = key; 1073 1074 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 1075 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1076 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 1077} 1078 1079#else /* GROUP_IOSCHED */ 1080static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) 1081{ 1082 return &cfqd->root_group; 1083} 1084static inline void 1085cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1086 cfqq->cfqg = cfqg; 1087} 1088 1089static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1090static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1091 1092#endif /* GROUP_IOSCHED */ 1093 1094/* 1095 * The cfqd->service_trees holds all pending cfq_queue's that have 1096 * requests waiting to be processed. It is sorted in the order that 1097 * we will service the queues. 1098 */ 1099static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1100 bool add_front) 1101{ 1102 struct rb_node **p, *parent; 1103 struct cfq_queue *__cfqq; 1104 unsigned long rb_key; 1105 struct cfq_rb_root *service_tree; 1106 int left; 1107 int new_cfqq = 1; 1108 int group_changed = 0; 1109 1110#ifdef CONFIG_CFQ_GROUP_IOSCHED 1111 if (!cfqd->cfq_group_isolation 1112 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD 1113 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) { 1114 /* Move this cfq to root group */ 1115 cfq_log_cfqq(cfqd, cfqq, "moving to root group"); 1116 if (!RB_EMPTY_NODE(&cfqq->rb_node)) 1117 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1118 cfqq->orig_cfqg = cfqq->cfqg; 1119 cfqq->cfqg = &cfqd->root_group; 1120 atomic_inc(&cfqd->root_group.ref); 1121 group_changed = 1; 1122 } else if (!cfqd->cfq_group_isolation 1123 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) { 1124 /* cfqq is sequential now needs to go to its original group */ 1125 BUG_ON(cfqq->cfqg != &cfqd->root_group); 1126 if (!RB_EMPTY_NODE(&cfqq->rb_node)) 1127 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1128 cfq_put_cfqg(cfqq->cfqg); 1129 cfqq->cfqg = cfqq->orig_cfqg; 1130 cfqq->orig_cfqg = NULL; 1131 group_changed = 1; 1132 cfq_log_cfqq(cfqd, cfqq, "moved to origin group"); 1133 } 1134#endif 1135 1136 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1137 cfqq_type(cfqq)); 1138 if (cfq_class_idle(cfqq)) { 1139 rb_key = CFQ_IDLE_DELAY; 1140 parent = rb_last(&service_tree->rb); 1141 if (parent && parent != &cfqq->rb_node) { 1142 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1143 rb_key += __cfqq->rb_key; 1144 } else 1145 rb_key += jiffies; 1146 } else if (!add_front) { 1147 /* 1148 * Get our rb key offset. Subtract any residual slice 1149 * value carried from last service. A negative resid 1150 * count indicates slice overrun, and this should position 1151 * the next service time further away in the tree. 1152 */ 1153 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1154 rb_key -= cfqq->slice_resid; 1155 cfqq->slice_resid = 0; 1156 } else { 1157 rb_key = -HZ; 1158 __cfqq = cfq_rb_first(service_tree); 1159 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1160 } 1161 1162 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1163 new_cfqq = 0; 1164 /* 1165 * same position, nothing more to do 1166 */ 1167 if (rb_key == cfqq->rb_key && 1168 cfqq->service_tree == service_tree) 1169 return; 1170 1171 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1172 cfqq->service_tree = NULL; 1173 } 1174 1175 left = 1; 1176 parent = NULL; 1177 cfqq->service_tree = service_tree; 1178 p = &service_tree->rb.rb_node; 1179 while (*p) { 1180 struct rb_node **n; 1181 1182 parent = *p; 1183 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1184 1185 /* 1186 * sort by key, that represents service time. 1187 */ 1188 if (time_before(rb_key, __cfqq->rb_key)) 1189 n = &(*p)->rb_left; 1190 else { 1191 n = &(*p)->rb_right; 1192 left = 0; 1193 } 1194 1195 p = n; 1196 } 1197 1198 if (left) 1199 service_tree->left = &cfqq->rb_node; 1200 1201 cfqq->rb_key = rb_key; 1202 rb_link_node(&cfqq->rb_node, parent, p); 1203 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1204 service_tree->count++; 1205 if ((add_front || !new_cfqq) && !group_changed) 1206 return; 1207 cfq_group_service_tree_add(cfqd, cfqq->cfqg); 1208} 1209 1210static struct cfq_queue * 1211cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1212 sector_t sector, struct rb_node **ret_parent, 1213 struct rb_node ***rb_link) 1214{ 1215 struct rb_node **p, *parent; 1216 struct cfq_queue *cfqq = NULL; 1217 1218 parent = NULL; 1219 p = &root->rb_node; 1220 while (*p) { 1221 struct rb_node **n; 1222 1223 parent = *p; 1224 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1225 1226 /* 1227 * Sort strictly based on sector. Smallest to the left, 1228 * largest to the right. 1229 */ 1230 if (sector > blk_rq_pos(cfqq->next_rq)) 1231 n = &(*p)->rb_right; 1232 else if (sector < blk_rq_pos(cfqq->next_rq)) 1233 n = &(*p)->rb_left; 1234 else 1235 break; 1236 p = n; 1237 cfqq = NULL; 1238 } 1239 1240 *ret_parent = parent; 1241 if (rb_link) 1242 *rb_link = p; 1243 return cfqq; 1244} 1245 1246static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1247{ 1248 struct rb_node **p, *parent; 1249 struct cfq_queue *__cfqq; 1250 1251 if (cfqq->p_root) { 1252 rb_erase(&cfqq->p_node, cfqq->p_root); 1253 cfqq->p_root = NULL; 1254 } 1255 1256 if (cfq_class_idle(cfqq)) 1257 return; 1258 if (!cfqq->next_rq) 1259 return; 1260 1261 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1262 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1263 blk_rq_pos(cfqq->next_rq), &parent, &p); 1264 if (!__cfqq) { 1265 rb_link_node(&cfqq->p_node, parent, p); 1266 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1267 } else 1268 cfqq->p_root = NULL; 1269} 1270 1271/* 1272 * Update cfqq's position in the service tree. 1273 */ 1274static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1275{ 1276 /* 1277 * Resorting requires the cfqq to be on the RR list already. 1278 */ 1279 if (cfq_cfqq_on_rr(cfqq)) { 1280 cfq_service_tree_add(cfqd, cfqq, 0); 1281 cfq_prio_tree_add(cfqd, cfqq); 1282 } 1283} 1284 1285/* 1286 * add to busy list of queues for service, trying to be fair in ordering 1287 * the pending list according to last request service 1288 */ 1289static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1290{ 1291 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1292 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1293 cfq_mark_cfqq_on_rr(cfqq); 1294 cfqd->busy_queues++; 1295 1296 cfq_resort_rr_list(cfqd, cfqq); 1297} 1298 1299/* 1300 * Called when the cfqq no longer has requests pending, remove it from 1301 * the service tree. 1302 */ 1303static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1304{ 1305 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1306 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1307 cfq_clear_cfqq_on_rr(cfqq); 1308 1309 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1310 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1311 cfqq->service_tree = NULL; 1312 } 1313 if (cfqq->p_root) { 1314 rb_erase(&cfqq->p_node, cfqq->p_root); 1315 cfqq->p_root = NULL; 1316 } 1317 1318 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1319 BUG_ON(!cfqd->busy_queues); 1320 cfqd->busy_queues--; 1321} 1322 1323/* 1324 * rb tree support functions 1325 */ 1326static void cfq_del_rq_rb(struct request *rq) 1327{ 1328 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1329 const int sync = rq_is_sync(rq); 1330 1331 BUG_ON(!cfqq->queued[sync]); 1332 cfqq->queued[sync]--; 1333 1334 elv_rb_del(&cfqq->sort_list, rq); 1335 1336 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1337 /* 1338 * Queue will be deleted from service tree when we actually 1339 * expire it later. Right now just remove it from prio tree 1340 * as it is empty. 1341 */ 1342 if (cfqq->p_root) { 1343 rb_erase(&cfqq->p_node, cfqq->p_root); 1344 cfqq->p_root = NULL; 1345 } 1346 } 1347} 1348 1349static void cfq_add_rq_rb(struct request *rq) 1350{ 1351 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1352 struct cfq_data *cfqd = cfqq->cfqd; 1353 struct request *__alias, *prev; 1354 1355 cfqq->queued[rq_is_sync(rq)]++; 1356 1357 /* 1358 * looks a little odd, but the first insert might return an alias. 1359 * if that happens, put the alias on the dispatch list 1360 */ 1361 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) 1362 cfq_dispatch_insert(cfqd->queue, __alias); 1363 1364 if (!cfq_cfqq_on_rr(cfqq)) 1365 cfq_add_cfqq_rr(cfqd, cfqq); 1366 1367 /* 1368 * check if this request is a better next-serve candidate 1369 */ 1370 prev = cfqq->next_rq; 1371 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1372 1373 /* 1374 * adjust priority tree position, if ->next_rq changes 1375 */ 1376 if (prev != cfqq->next_rq) 1377 cfq_prio_tree_add(cfqd, cfqq); 1378 1379 BUG_ON(!cfqq->next_rq); 1380} 1381 1382static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1383{ 1384 elv_rb_del(&cfqq->sort_list, rq); 1385 cfqq->queued[rq_is_sync(rq)]--; 1386 cfq_add_rq_rb(rq); 1387} 1388 1389static struct request * 1390cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1391{ 1392 struct task_struct *tsk = current; 1393 struct cfq_io_context *cic; 1394 struct cfq_queue *cfqq; 1395 1396 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1397 if (!cic) 1398 return NULL; 1399 1400 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1401 if (cfqq) { 1402 sector_t sector = bio->bi_sector + bio_sectors(bio); 1403 1404 return elv_rb_find(&cfqq->sort_list, sector); 1405 } 1406 1407 return NULL; 1408} 1409 1410static void cfq_activate_request(struct request_queue *q, struct request *rq) 1411{ 1412 struct cfq_data *cfqd = q->elevator->elevator_data; 1413 1414 cfqd->rq_in_driver++; 1415 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1416 cfqd->rq_in_driver); 1417 1418 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1419} 1420 1421static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1422{ 1423 struct cfq_data *cfqd = q->elevator->elevator_data; 1424 1425 WARN_ON(!cfqd->rq_in_driver); 1426 cfqd->rq_in_driver--; 1427 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1428 cfqd->rq_in_driver); 1429} 1430 1431static void cfq_remove_request(struct request *rq) 1432{ 1433 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1434 1435 if (cfqq->next_rq == rq) 1436 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1437 1438 list_del_init(&rq->queuelist); 1439 cfq_del_rq_rb(rq); 1440 1441 cfqq->cfqd->rq_queued--; 1442 if (rq_is_meta(rq)) { 1443 WARN_ON(!cfqq->meta_pending); 1444 cfqq->meta_pending--; 1445 } 1446} 1447 1448static int cfq_merge(struct request_queue *q, struct request **req, 1449 struct bio *bio) 1450{ 1451 struct cfq_data *cfqd = q->elevator->elevator_data; 1452 struct request *__rq; 1453 1454 __rq = cfq_find_rq_fmerge(cfqd, bio); 1455 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1456 *req = __rq; 1457 return ELEVATOR_FRONT_MERGE; 1458 } 1459 1460 return ELEVATOR_NO_MERGE; 1461} 1462 1463static void cfq_merged_request(struct request_queue *q, struct request *req, 1464 int type) 1465{ 1466 if (type == ELEVATOR_FRONT_MERGE) { 1467 struct cfq_queue *cfqq = RQ_CFQQ(req); 1468 1469 cfq_reposition_rq_rb(cfqq, req); 1470 } 1471} 1472 1473static void 1474cfq_merged_requests(struct request_queue *q, struct request *rq, 1475 struct request *next) 1476{ 1477 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1478 /* 1479 * reposition in fifo if next is older than rq 1480 */ 1481 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1482 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1483 list_move(&rq->queuelist, &next->queuelist); 1484 rq_set_fifo_time(rq, rq_fifo_time(next)); 1485 } 1486 1487 if (cfqq->next_rq == next) 1488 cfqq->next_rq = rq; 1489 cfq_remove_request(next); 1490} 1491 1492static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1493 struct bio *bio) 1494{ 1495 struct cfq_data *cfqd = q->elevator->elevator_data; 1496 struct cfq_io_context *cic; 1497 struct cfq_queue *cfqq; 1498 1499 /* 1500 * Disallow merge of a sync bio into an async request. 1501 */ 1502 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1503 return false; 1504 1505 /* 1506 * Lookup the cfqq that this bio will be queued with. Allow 1507 * merge only if rq is queued there. 1508 */ 1509 cic = cfq_cic_lookup(cfqd, current->io_context); 1510 if (!cic) 1511 return false; 1512 1513 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1514 return cfqq == RQ_CFQQ(rq); 1515} 1516 1517static void __cfq_set_active_queue(struct cfq_data *cfqd, 1518 struct cfq_queue *cfqq) 1519{ 1520 if (cfqq) { 1521 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1522 cfqd->serving_prio, cfqd->serving_type); 1523 cfqq->slice_start = 0; 1524 cfqq->dispatch_start = jiffies; 1525 cfqq->allocated_slice = 0; 1526 cfqq->slice_end = 0; 1527 cfqq->slice_dispatch = 0; 1528 cfqq->nr_sectors = 0; 1529 1530 cfq_clear_cfqq_wait_request(cfqq); 1531 cfq_clear_cfqq_must_dispatch(cfqq); 1532 cfq_clear_cfqq_must_alloc_slice(cfqq); 1533 cfq_clear_cfqq_fifo_expire(cfqq); 1534 cfq_mark_cfqq_slice_new(cfqq); 1535 1536 del_timer(&cfqd->idle_slice_timer); 1537 } 1538 1539 cfqd->active_queue = cfqq; 1540} 1541 1542/* 1543 * current cfqq expired its slice (or was too idle), select new one 1544 */ 1545static void 1546__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1547 bool timed_out) 1548{ 1549 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1550 1551 if (cfq_cfqq_wait_request(cfqq)) 1552 del_timer(&cfqd->idle_slice_timer); 1553 1554 cfq_clear_cfqq_wait_request(cfqq); 1555 cfq_clear_cfqq_wait_busy(cfqq); 1556 1557 /* 1558 * If this cfqq is shared between multiple processes, check to 1559 * make sure that those processes are still issuing I/Os within 1560 * the mean seek distance. If not, it may be time to break the 1561 * queues apart again. 1562 */ 1563 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1564 cfq_mark_cfqq_split_coop(cfqq); 1565 1566 /* 1567 * store what was left of this slice, if the queue idled/timed out 1568 */ 1569 if (timed_out && !cfq_cfqq_slice_new(cfqq)) { 1570 cfqq->slice_resid = cfqq->slice_end - jiffies; 1571 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1572 } 1573 1574 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1575 1576 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1577 cfq_del_cfqq_rr(cfqd, cfqq); 1578 1579 cfq_resort_rr_list(cfqd, cfqq); 1580 1581 if (cfqq == cfqd->active_queue) 1582 cfqd->active_queue = NULL; 1583 1584 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active) 1585 cfqd->grp_service_tree.active = NULL; 1586 1587 if (cfqd->active_cic) { 1588 put_io_context(cfqd->active_cic->ioc); 1589 cfqd->active_cic = NULL; 1590 } 1591} 1592 1593static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1594{ 1595 struct cfq_queue *cfqq = cfqd->active_queue; 1596 1597 if (cfqq) 1598 __cfq_slice_expired(cfqd, cfqq, timed_out); 1599} 1600 1601/* 1602 * Get next queue for service. Unless we have a queue preemption, 1603 * we'll simply select the first cfqq in the service tree. 1604 */ 1605static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1606{ 1607 struct cfq_rb_root *service_tree = 1608 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1609 cfqd->serving_type); 1610 1611 if (!cfqd->rq_queued) 1612 return NULL; 1613 1614 /* There is nothing to dispatch */ 1615 if (!service_tree) 1616 return NULL; 1617 if (RB_EMPTY_ROOT(&service_tree->rb)) 1618 return NULL; 1619 return cfq_rb_first(service_tree); 1620} 1621 1622static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1623{ 1624 struct cfq_group *cfqg; 1625 struct cfq_queue *cfqq; 1626 int i, j; 1627 struct cfq_rb_root *st; 1628 1629 if (!cfqd->rq_queued) 1630 return NULL; 1631 1632 cfqg = cfq_get_next_cfqg(cfqd); 1633 if (!cfqg) 1634 return NULL; 1635 1636 for_each_cfqg_st(cfqg, i, j, st) 1637 if ((cfqq = cfq_rb_first(st)) != NULL) 1638 return cfqq; 1639 return NULL; 1640} 1641 1642/* 1643 * Get and set a new active queue for service. 1644 */ 1645static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1646 struct cfq_queue *cfqq) 1647{ 1648 if (!cfqq) 1649 cfqq = cfq_get_next_queue(cfqd); 1650 1651 __cfq_set_active_queue(cfqd, cfqq); 1652 return cfqq; 1653} 1654 1655static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1656 struct request *rq) 1657{ 1658 if (blk_rq_pos(rq) >= cfqd->last_position) 1659 return blk_rq_pos(rq) - cfqd->last_position; 1660 else 1661 return cfqd->last_position - blk_rq_pos(rq); 1662} 1663 1664static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1665 struct request *rq) 1666{ 1667 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1668} 1669 1670static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1671 struct cfq_queue *cur_cfqq) 1672{ 1673 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1674 struct rb_node *parent, *node; 1675 struct cfq_queue *__cfqq; 1676 sector_t sector = cfqd->last_position; 1677 1678 if (RB_EMPTY_ROOT(root)) 1679 return NULL; 1680 1681 /* 1682 * First, if we find a request starting at the end of the last 1683 * request, choose it. 1684 */ 1685 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1686 if (__cfqq) 1687 return __cfqq; 1688 1689 /* 1690 * If the exact sector wasn't found, the parent of the NULL leaf 1691 * will contain the closest sector. 1692 */ 1693 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1694 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1695 return __cfqq; 1696 1697 if (blk_rq_pos(__cfqq->next_rq) < sector) 1698 node = rb_next(&__cfqq->p_node); 1699 else 1700 node = rb_prev(&__cfqq->p_node); 1701 if (!node) 1702 return NULL; 1703 1704 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1705 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1706 return __cfqq; 1707 1708 return NULL; 1709} 1710 1711/* 1712 * cfqd - obvious 1713 * cur_cfqq - passed in so that we don't decide that the current queue is 1714 * closely cooperating with itself. 1715 * 1716 * So, basically we're assuming that that cur_cfqq has dispatched at least 1717 * one request, and that cfqd->last_position reflects a position on the disk 1718 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1719 * assumption. 1720 */ 1721static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1722 struct cfq_queue *cur_cfqq) 1723{ 1724 struct cfq_queue *cfqq; 1725 1726 if (!cfq_cfqq_sync(cur_cfqq)) 1727 return NULL; 1728 if (CFQQ_SEEKY(cur_cfqq)) 1729 return NULL; 1730 1731 /* 1732 * Don't search priority tree if it's the only queue in the group. 1733 */ 1734 if (cur_cfqq->cfqg->nr_cfqq == 1) 1735 return NULL; 1736 1737 /* 1738 * We should notice if some of the queues are cooperating, eg 1739 * working closely on the same area of the disk. In that case, 1740 * we can group them together and don't waste time idling. 1741 */ 1742 cfqq = cfqq_close(cfqd, cur_cfqq); 1743 if (!cfqq) 1744 return NULL; 1745 1746 /* If new queue belongs to different cfq_group, don't choose it */ 1747 if (cur_cfqq->cfqg != cfqq->cfqg) 1748 return NULL; 1749 1750 /* 1751 * It only makes sense to merge sync queues. 1752 */ 1753 if (!cfq_cfqq_sync(cfqq)) 1754 return NULL; 1755 if (CFQQ_SEEKY(cfqq)) 1756 return NULL; 1757 1758 /* 1759 * Do not merge queues of different priority classes 1760 */ 1761 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1762 return NULL; 1763 1764 return cfqq; 1765} 1766 1767/* 1768 * Determine whether we should enforce idle window for this queue. 1769 */ 1770 1771static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1772{ 1773 enum wl_prio_t prio = cfqq_prio(cfqq); 1774 struct cfq_rb_root *service_tree = cfqq->service_tree; 1775 1776 BUG_ON(!service_tree); 1777 BUG_ON(!service_tree->count); 1778 1779 /* We never do for idle class queues. */ 1780 if (prio == IDLE_WORKLOAD) 1781 return false; 1782 1783 /* We do for queues that were marked with idle window flag. */ 1784 if (cfq_cfqq_idle_window(cfqq) && 1785 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 1786 return true; 1787 1788 /* 1789 * Otherwise, we do only if they are the last ones 1790 * in their service tree. 1791 */ 1792 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) 1793 return 1; 1794 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 1795 service_tree->count); 1796 return 0; 1797} 1798 1799static void cfq_arm_slice_timer(struct cfq_data *cfqd) 1800{ 1801 struct cfq_queue *cfqq = cfqd->active_queue; 1802 struct cfq_io_context *cic; 1803 unsigned long sl; 1804 1805 /* 1806 * SSD device without seek penalty, disable idling. But only do so 1807 * for devices that support queuing, otherwise we still have a problem 1808 * with sync vs async workloads. 1809 */ 1810 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 1811 return; 1812 1813 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 1814 WARN_ON(cfq_cfqq_slice_new(cfqq)); 1815 1816 /* 1817 * idle is disabled, either manually or by past process history 1818 */ 1819 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) 1820 return; 1821 1822 /* 1823 * still active requests from this queue, don't idle 1824 */ 1825 if (cfqq->dispatched) 1826 return; 1827 1828 /* 1829 * task has exited, don't wait 1830 */ 1831 cic = cfqd->active_cic; 1832 if (!cic || !atomic_read(&cic->ioc->nr_tasks)) 1833 return; 1834 1835 /* 1836 * If our average think time is larger than the remaining time 1837 * slice, then don't idle. This avoids overrunning the allotted 1838 * time slice. 1839 */ 1840 if (sample_valid(cic->ttime_samples) && 1841 (cfqq->slice_end - jiffies < cic->ttime_mean)) { 1842 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d", 1843 cic->ttime_mean); 1844 return; 1845 } 1846 1847 cfq_mark_cfqq_wait_request(cfqq); 1848 1849 sl = cfqd->cfq_slice_idle; 1850 1851 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 1852 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); 1853} 1854 1855/* 1856 * Move request from internal lists to the request queue dispatch list. 1857 */ 1858static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 1859{ 1860 struct cfq_data *cfqd = q->elevator->elevator_data; 1861 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1862 1863 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 1864 1865 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 1866 cfq_remove_request(rq); 1867 cfqq->dispatched++; 1868 elv_dispatch_sort(q, rq); 1869 1870 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 1871 cfqq->nr_sectors += blk_rq_sectors(rq); 1872} 1873 1874/* 1875 * return expired entry, or NULL to just start from scratch in rbtree 1876 */ 1877static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 1878{ 1879 struct request *rq = NULL; 1880 1881 if (cfq_cfqq_fifo_expire(cfqq)) 1882 return NULL; 1883 1884 cfq_mark_cfqq_fifo_expire(cfqq); 1885 1886 if (list_empty(&cfqq->fifo)) 1887 return NULL; 1888 1889 rq = rq_entry_fifo(cfqq->fifo.next); 1890 if (time_before(jiffies, rq_fifo_time(rq))) 1891 rq = NULL; 1892 1893 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 1894 return rq; 1895} 1896 1897static inline int 1898cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1899{ 1900 const int base_rq = cfqd->cfq_slice_async_rq; 1901 1902 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 1903 1904 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); 1905} 1906 1907/* 1908 * Must be called with the queue_lock held. 1909 */ 1910static int cfqq_process_refs(struct cfq_queue *cfqq) 1911{ 1912 int process_refs, io_refs; 1913 1914 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 1915 process_refs = atomic_read(&cfqq->ref) - io_refs; 1916 BUG_ON(process_refs < 0); 1917 return process_refs; 1918} 1919 1920static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 1921{ 1922 int process_refs, new_process_refs; 1923 struct cfq_queue *__cfqq; 1924 1925 /* Avoid a circular list and skip interim queue merges */ 1926 while ((__cfqq = new_cfqq->new_cfqq)) { 1927 if (__cfqq == cfqq) 1928 return; 1929 new_cfqq = __cfqq; 1930 } 1931 1932 process_refs = cfqq_process_refs(cfqq); 1933 /* 1934 * If the process for the cfqq has gone away, there is no 1935 * sense in merging the queues. 1936 */ 1937 if (process_refs == 0) 1938 return; 1939 1940 /* 1941 * Merge in the direction of the lesser amount of work. 1942 */ 1943 new_process_refs = cfqq_process_refs(new_cfqq); 1944 if (new_process_refs >= process_refs) { 1945 cfqq->new_cfqq = new_cfqq; 1946 atomic_add(process_refs, &new_cfqq->ref); 1947 } else { 1948 new_cfqq->new_cfqq = cfqq; 1949 atomic_add(new_process_refs, &cfqq->ref); 1950 } 1951} 1952 1953static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 1954 struct cfq_group *cfqg, enum wl_prio_t prio) 1955{ 1956 struct cfq_queue *queue; 1957 int i; 1958 bool key_valid = false; 1959 unsigned long lowest_key = 0; 1960 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 1961 1962 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 1963 /* select the one with lowest rb_key */ 1964 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 1965 if (queue && 1966 (!key_valid || time_before(queue->rb_key, lowest_key))) { 1967 lowest_key = queue->rb_key; 1968 cur_best = i; 1969 key_valid = true; 1970 } 1971 } 1972 1973 return cur_best; 1974} 1975 1976static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 1977{ 1978 unsigned slice; 1979 unsigned count; 1980 struct cfq_rb_root *st; 1981 unsigned group_slice; 1982 1983 if (!cfqg) { 1984 cfqd->serving_prio = IDLE_WORKLOAD; 1985 cfqd->workload_expires = jiffies + 1; 1986 return; 1987 } 1988 1989 /* Choose next priority. RT > BE > IDLE */ 1990 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 1991 cfqd->serving_prio = RT_WORKLOAD; 1992 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 1993 cfqd->serving_prio = BE_WORKLOAD; 1994 else { 1995 cfqd->serving_prio = IDLE_WORKLOAD; 1996 cfqd->workload_expires = jiffies + 1; 1997 return; 1998 } 1999 2000 /* 2001 * For RT and BE, we have to choose also the type 2002 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2003 * expiration time 2004 */ 2005 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2006 count = st->count; 2007 2008 /* 2009 * check workload expiration, and that we still have other queues ready 2010 */ 2011 if (count && !time_after(jiffies, cfqd->workload_expires)) 2012 return; 2013 2014 /* otherwise select new workload type */ 2015 cfqd->serving_type = 2016 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2017 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2018 count = st->count; 2019 2020 /* 2021 * the workload slice is computed as a fraction of target latency 2022 * proportional to the number of queues in that workload, over 2023 * all the queues in the same priority class 2024 */ 2025 group_slice = cfq_group_slice(cfqd, cfqg); 2026 2027 slice = group_slice * count / 2028 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2029 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2030 2031 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2032 unsigned int tmp; 2033 2034 /* 2035 * Async queues are currently system wide. Just taking 2036 * proportion of queues with-in same group will lead to higher 2037 * async ratio system wide as generally root group is going 2038 * to have higher weight. A more accurate thing would be to 2039 * calculate system wide asnc/sync ratio. 2040 */ 2041 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2042 tmp = tmp/cfqd->busy_queues; 2043 slice = min_t(unsigned, slice, tmp); 2044 2045 /* async workload slice is scaled down according to 2046 * the sync/async slice ratio. */ 2047 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2048 } else 2049 /* sync workload slice is at least 2 * cfq_slice_idle */ 2050 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2051 2052 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2053 cfq_log(cfqd, "workload slice:%d", slice); 2054 cfqd->workload_expires = jiffies + slice; 2055 cfqd->noidle_tree_requires_idle = false; 2056} 2057 2058static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2059{ 2060 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2061 struct cfq_group *cfqg; 2062 2063 if (RB_EMPTY_ROOT(&st->rb)) 2064 return NULL; 2065 cfqg = cfq_rb_first_group(st); 2066 st->active = &cfqg->rb_node; 2067 update_min_vdisktime(st); 2068 return cfqg; 2069} 2070 2071static void cfq_choose_cfqg(struct cfq_data *cfqd) 2072{ 2073 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2074 2075 cfqd->serving_group = cfqg; 2076 2077 /* Restore the workload type data */ 2078 if (cfqg->saved_workload_slice) { 2079 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2080 cfqd->serving_type = cfqg->saved_workload; 2081 cfqd->serving_prio = cfqg->saved_serving_prio; 2082 } else 2083 cfqd->workload_expires = jiffies - 1; 2084 2085 choose_service_tree(cfqd, cfqg); 2086} 2087 2088/* 2089 * Select a queue for service. If we have a current active queue, 2090 * check whether to continue servicing it, or retrieve and set a new one. 2091 */ 2092static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2093{ 2094 struct cfq_queue *cfqq, *new_cfqq = NULL; 2095 2096 cfqq = cfqd->active_queue; 2097 if (!cfqq) 2098 goto new_queue; 2099 2100 if (!cfqd->rq_queued) 2101 return NULL; 2102 2103 /* 2104 * We were waiting for group to get backlogged. Expire the queue 2105 */ 2106 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2107 goto expire; 2108 2109 /* 2110 * The active queue has run out of time, expire it and select new. 2111 */ 2112 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2113 /* 2114 * If slice had not expired at the completion of last request 2115 * we might not have turned on wait_busy flag. Don't expire 2116 * the queue yet. Allow the group to get backlogged. 2117 * 2118 * The very fact that we have used the slice, that means we 2119 * have been idling all along on this queue and it should be 2120 * ok to wait for this request to complete. 2121 */ 2122 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2123 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2124 cfqq = NULL; 2125 goto keep_queue; 2126 } else 2127 goto expire; 2128 } 2129 2130 /* 2131 * The active queue has requests and isn't expired, allow it to 2132 * dispatch. 2133 */ 2134 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2135 goto keep_queue; 2136 2137 /* 2138 * If another queue has a request waiting within our mean seek 2139 * distance, let it run. The expire code will check for close 2140 * cooperators and put the close queue at the front of the service 2141 * tree. If possible, merge the expiring queue with the new cfqq. 2142 */ 2143 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2144 if (new_cfqq) { 2145 if (!cfqq->new_cfqq) 2146 cfq_setup_merge(cfqq, new_cfqq); 2147 goto expire; 2148 } 2149 2150 /* 2151 * No requests pending. If the active queue still has requests in 2152 * flight or is idling for a new request, allow either of these 2153 * conditions to happen (or time out) before selecting a new queue. 2154 */ 2155 if (timer_pending(&cfqd->idle_slice_timer) || 2156 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { 2157 cfqq = NULL; 2158 goto keep_queue; 2159 } 2160 2161expire: 2162 cfq_slice_expired(cfqd, 0); 2163new_queue: 2164 /* 2165 * Current queue expired. Check if we have to switch to a new 2166 * service tree 2167 */ 2168 if (!new_cfqq) 2169 cfq_choose_cfqg(cfqd); 2170 2171 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2172keep_queue: 2173 return cfqq; 2174} 2175 2176static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2177{ 2178 int dispatched = 0; 2179 2180 while (cfqq->next_rq) { 2181 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2182 dispatched++; 2183 } 2184 2185 BUG_ON(!list_empty(&cfqq->fifo)); 2186 2187 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2188 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2189 return dispatched; 2190} 2191 2192/* 2193 * Drain our current requests. Used for barriers and when switching 2194 * io schedulers on-the-fly. 2195 */ 2196static int cfq_forced_dispatch(struct cfq_data *cfqd) 2197{ 2198 struct cfq_queue *cfqq; 2199 int dispatched = 0; 2200 2201 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) 2202 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2203 2204 cfq_slice_expired(cfqd, 0); 2205 BUG_ON(cfqd->busy_queues); 2206 2207 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2208 return dispatched; 2209} 2210 2211static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2212 struct cfq_queue *cfqq) 2213{ 2214 /* the queue hasn't finished any request, can't estimate */ 2215 if (cfq_cfqq_slice_new(cfqq)) 2216 return 1; 2217 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2218 cfqq->slice_end)) 2219 return 1; 2220 2221 return 0; 2222} 2223 2224static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2225{ 2226 unsigned int max_dispatch; 2227 2228 /* 2229 * Drain async requests before we start sync IO 2230 */ 2231 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2232 return false; 2233 2234 /* 2235 * If this is an async queue and we have sync IO in flight, let it wait 2236 */ 2237 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2238 return false; 2239 2240 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2241 if (cfq_class_idle(cfqq)) 2242 max_dispatch = 1; 2243 2244 /* 2245 * Does this cfqq already have too much IO in flight? 2246 */ 2247 if (cfqq->dispatched >= max_dispatch) { 2248 /* 2249 * idle queue must always only have a single IO in flight 2250 */ 2251 if (cfq_class_idle(cfqq)) 2252 return false; 2253 2254 /* 2255 * We have other queues, don't allow more IO from this one 2256 */ 2257 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq)) 2258 return false; 2259 2260 /* 2261 * Sole queue user, no limit 2262 */ 2263 if (cfqd->busy_queues == 1) 2264 max_dispatch = -1; 2265 else 2266 /* 2267 * Normally we start throttling cfqq when cfq_quantum/2 2268 * requests have been dispatched. But we can drive 2269 * deeper queue depths at the beginning of slice 2270 * subjected to upper limit of cfq_quantum. 2271 * */ 2272 max_dispatch = cfqd->cfq_quantum; 2273 } 2274 2275 /* 2276 * Async queues must wait a bit before being allowed dispatch. 2277 * We also ramp up the dispatch depth gradually for async IO, 2278 * based on the last sync IO we serviced 2279 */ 2280 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2281 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2282 unsigned int depth; 2283 2284 depth = last_sync / cfqd->cfq_slice[1]; 2285 if (!depth && !cfqq->dispatched) 2286 depth = 1; 2287 if (depth < max_dispatch) 2288 max_dispatch = depth; 2289 } 2290 2291 /* 2292 * If we're below the current max, allow a dispatch 2293 */ 2294 return cfqq->dispatched < max_dispatch; 2295} 2296 2297/* 2298 * Dispatch a request from cfqq, moving them to the request queue 2299 * dispatch list. 2300 */ 2301static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2302{ 2303 struct request *rq; 2304 2305 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2306 2307 if (!cfq_may_dispatch(cfqd, cfqq)) 2308 return false; 2309 2310 /* 2311 * follow expired path, else get first next available 2312 */ 2313 rq = cfq_check_fifo(cfqq); 2314 if (!rq) 2315 rq = cfqq->next_rq; 2316 2317 /* 2318 * insert request into driver dispatch list 2319 */ 2320 cfq_dispatch_insert(cfqd->queue, rq); 2321 2322 if (!cfqd->active_cic) { 2323 struct cfq_io_context *cic = RQ_CIC(rq); 2324 2325 atomic_long_inc(&cic->ioc->refcount); 2326 cfqd->active_cic = cic; 2327 } 2328 2329 return true; 2330} 2331 2332/* 2333 * Find the cfqq that we need to service and move a request from that to the 2334 * dispatch list 2335 */ 2336static int cfq_dispatch_requests(struct request_queue *q, int force) 2337{ 2338 struct cfq_data *cfqd = q->elevator->elevator_data; 2339 struct cfq_queue *cfqq; 2340 2341 if (!cfqd->busy_queues) 2342 return 0; 2343 2344 if (unlikely(force)) 2345 return cfq_forced_dispatch(cfqd); 2346 2347 cfqq = cfq_select_queue(cfqd); 2348 if (!cfqq) 2349 return 0; 2350 2351 /* 2352 * Dispatch a request from this cfqq, if it is allowed 2353 */ 2354 if (!cfq_dispatch_request(cfqd, cfqq)) 2355 return 0; 2356 2357 cfqq->slice_dispatch++; 2358 cfq_clear_cfqq_must_dispatch(cfqq); 2359 2360 /* 2361 * expire an async queue immediately if it has used up its slice. idle 2362 * queue always expire after 1 dispatch round. 2363 */ 2364 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2365 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2366 cfq_class_idle(cfqq))) { 2367 cfqq->slice_end = jiffies + 1; 2368 cfq_slice_expired(cfqd, 0); 2369 } 2370 2371 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2372 return 1; 2373} 2374 2375/* 2376 * task holds one reference to the queue, dropped when task exits. each rq 2377 * in-flight on this queue also holds a reference, dropped when rq is freed. 2378 * 2379 * Each cfq queue took a reference on the parent group. Drop it now. 2380 * queue lock must be held here. 2381 */ 2382static void cfq_put_queue(struct cfq_queue *cfqq) 2383{ 2384 struct cfq_data *cfqd = cfqq->cfqd; 2385 struct cfq_group *cfqg, *orig_cfqg; 2386 2387 BUG_ON(atomic_read(&cfqq->ref) <= 0); 2388 2389 if (!atomic_dec_and_test(&cfqq->ref)) 2390 return; 2391 2392 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2393 BUG_ON(rb_first(&cfqq->sort_list)); 2394 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2395 cfqg = cfqq->cfqg; 2396 orig_cfqg = cfqq->orig_cfqg; 2397 2398 if (unlikely(cfqd->active_queue == cfqq)) { 2399 __cfq_slice_expired(cfqd, cfqq, 0); 2400 cfq_schedule_dispatch(cfqd); 2401 } 2402 2403 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2404 kmem_cache_free(cfq_pool, cfqq); 2405 cfq_put_cfqg(cfqg); 2406 if (orig_cfqg) 2407 cfq_put_cfqg(orig_cfqg); 2408} 2409 2410/* 2411 * Must always be called with the rcu_read_lock() held 2412 */ 2413static void 2414__call_for_each_cic(struct io_context *ioc, 2415 void (*func)(struct io_context *, struct cfq_io_context *)) 2416{ 2417 struct cfq_io_context *cic; 2418 struct hlist_node *n; 2419 2420 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) 2421 func(ioc, cic); 2422} 2423 2424/* 2425 * Call func for each cic attached to this ioc. 2426 */ 2427static void 2428call_for_each_cic(struct io_context *ioc, 2429 void (*func)(struct io_context *, struct cfq_io_context *)) 2430{ 2431 rcu_read_lock(); 2432 __call_for_each_cic(ioc, func); 2433 rcu_read_unlock(); 2434} 2435 2436static void cfq_cic_free_rcu(struct rcu_head *head) 2437{ 2438 struct cfq_io_context *cic; 2439 2440 cic = container_of(head, struct cfq_io_context, rcu_head); 2441 2442 kmem_cache_free(cfq_ioc_pool, cic); 2443 elv_ioc_count_dec(cfq_ioc_count); 2444 2445 if (ioc_gone) { 2446 /* 2447 * CFQ scheduler is exiting, grab exit lock and check 2448 * the pending io context count. If it hits zero, 2449 * complete ioc_gone and set it back to NULL 2450 */ 2451 spin_lock(&ioc_gone_lock); 2452 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { 2453 complete(ioc_gone); 2454 ioc_gone = NULL; 2455 } 2456 spin_unlock(&ioc_gone_lock); 2457 } 2458} 2459 2460static void cfq_cic_free(struct cfq_io_context *cic) 2461{ 2462 call_rcu(&cic->rcu_head, cfq_cic_free_rcu); 2463} 2464 2465static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) 2466{ 2467 unsigned long flags; 2468 2469 BUG_ON(!cic->dead_key); 2470 2471 spin_lock_irqsave(&ioc->lock, flags); 2472 radix_tree_delete(&ioc->radix_root, cic->dead_key); 2473 hlist_del_rcu(&cic->cic_list); 2474 spin_unlock_irqrestore(&ioc->lock, flags); 2475 2476 cfq_cic_free(cic); 2477} 2478 2479/* 2480 * Must be called with rcu_read_lock() held or preemption otherwise disabled. 2481 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), 2482 * and ->trim() which is called with the task lock held 2483 */ 2484static void cfq_free_io_context(struct io_context *ioc) 2485{ 2486 /* 2487 * ioc->refcount is zero here, or we are called from elv_unregister(), 2488 * so no more cic's are allowed to be linked into this ioc. So it 2489 * should be ok to iterate over the known list, we will see all cic's 2490 * since no new ones are added. 2491 */ 2492 __call_for_each_cic(ioc, cic_free_func); 2493} 2494 2495static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2496{ 2497 struct cfq_queue *__cfqq, *next; 2498 2499 if (unlikely(cfqq == cfqd->active_queue)) { 2500 __cfq_slice_expired(cfqd, cfqq, 0); 2501 cfq_schedule_dispatch(cfqd); 2502 } 2503 2504 /* 2505 * If this queue was scheduled to merge with another queue, be 2506 * sure to drop the reference taken on that queue (and others in 2507 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2508 */ 2509 __cfqq = cfqq->new_cfqq; 2510 while (__cfqq) { 2511 if (__cfqq == cfqq) { 2512 WARN(1, "cfqq->new_cfqq loop detected\n"); 2513 break; 2514 } 2515 next = __cfqq->new_cfqq; 2516 cfq_put_queue(__cfqq); 2517 __cfqq = next; 2518 } 2519 2520 cfq_put_queue(cfqq); 2521} 2522 2523static void __cfq_exit_single_io_context(struct cfq_data *cfqd, 2524 struct cfq_io_context *cic) 2525{ 2526 struct io_context *ioc = cic->ioc; 2527 2528 list_del_init(&cic->queue_list); 2529 2530 /* 2531 * Make sure key == NULL is seen for dead queues 2532 */ 2533 smp_wmb(); 2534 cic->dead_key = (unsigned long) cic->key; 2535 cic->key = NULL; 2536 2537 if (ioc->ioc_data == cic) 2538 rcu_assign_pointer(ioc->ioc_data, NULL); 2539 2540 if (cic->cfqq[BLK_RW_ASYNC]) { 2541 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2542 cic->cfqq[BLK_RW_ASYNC] = NULL; 2543 } 2544 2545 if (cic->cfqq[BLK_RW_SYNC]) { 2546 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2547 cic->cfqq[BLK_RW_SYNC] = NULL; 2548 } 2549} 2550 2551static void cfq_exit_single_io_context(struct io_context *ioc, 2552 struct cfq_io_context *cic) 2553{ 2554 struct cfq_data *cfqd = cic->key; 2555 2556 if (cfqd) { 2557 struct request_queue *q = cfqd->queue; 2558 unsigned long flags; 2559 2560 spin_lock_irqsave(q->queue_lock, flags); 2561 2562 /* 2563 * Ensure we get a fresh copy of the ->key to prevent 2564 * race between exiting task and queue 2565 */ 2566 smp_read_barrier_depends(); 2567 if (cic->key) 2568 __cfq_exit_single_io_context(cfqd, cic); 2569 2570 spin_unlock_irqrestore(q->queue_lock, flags); 2571 } 2572} 2573 2574/* 2575 * The process that ioc belongs to has exited, we need to clean up 2576 * and put the internal structures we have that belongs to that process. 2577 */ 2578static void cfq_exit_io_context(struct io_context *ioc) 2579{ 2580 call_for_each_cic(ioc, cfq_exit_single_io_context); 2581} 2582 2583static struct cfq_io_context * 2584cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2585{ 2586 struct cfq_io_context *cic; 2587 2588 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, 2589 cfqd->queue->node); 2590 if (cic) { 2591 cic->last_end_request = jiffies; 2592 INIT_LIST_HEAD(&cic->queue_list); 2593 INIT_HLIST_NODE(&cic->cic_list); 2594 cic->dtor = cfq_free_io_context; 2595 cic->exit = cfq_exit_io_context; 2596 elv_ioc_count_inc(cfq_ioc_count); 2597 } 2598 2599 return cic; 2600} 2601 2602static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2603{ 2604 struct task_struct *tsk = current; 2605 int ioprio_class; 2606 2607 if (!cfq_cfqq_prio_changed(cfqq)) 2608 return; 2609 2610 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2611 switch (ioprio_class) { 2612 default: 2613 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2614 case IOPRIO_CLASS_NONE: 2615 /* 2616 * no prio set, inherit CPU scheduling settings 2617 */ 2618 cfqq->ioprio = task_nice_ioprio(tsk); 2619 cfqq->ioprio_class = task_nice_ioclass(tsk); 2620 break; 2621 case IOPRIO_CLASS_RT: 2622 cfqq->ioprio = task_ioprio(ioc); 2623 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2624 break; 2625 case IOPRIO_CLASS_BE: 2626 cfqq->ioprio = task_ioprio(ioc); 2627 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2628 break; 2629 case IOPRIO_CLASS_IDLE: 2630 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2631 cfqq->ioprio = 7; 2632 cfq_clear_cfqq_idle_window(cfqq); 2633 break; 2634 } 2635 2636 /* 2637 * keep track of original prio settings in case we have to temporarily 2638 * elevate the priority of this queue 2639 */ 2640 cfqq->org_ioprio = cfqq->ioprio; 2641 cfqq->org_ioprio_class = cfqq->ioprio_class; 2642 cfq_clear_cfqq_prio_changed(cfqq); 2643} 2644 2645static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) 2646{ 2647 struct cfq_data *cfqd = cic->key; 2648 struct cfq_queue *cfqq; 2649 unsigned long flags; 2650 2651 if (unlikely(!cfqd)) 2652 return; 2653 2654 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2655 2656 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2657 if (cfqq) { 2658 struct cfq_queue *new_cfqq; 2659 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, 2660 GFP_ATOMIC); 2661 if (new_cfqq) { 2662 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2663 cfq_put_queue(cfqq); 2664 } 2665 } 2666 2667 cfqq = cic->cfqq[BLK_RW_SYNC]; 2668 if (cfqq) 2669 cfq_mark_cfqq_prio_changed(cfqq); 2670 2671 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2672} 2673 2674static void cfq_ioc_set_ioprio(struct io_context *ioc) 2675{ 2676 call_for_each_cic(ioc, changed_ioprio); 2677 ioc->ioprio_changed = 0; 2678} 2679 2680static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2681 pid_t pid, bool is_sync) 2682{ 2683 RB_CLEAR_NODE(&cfqq->rb_node); 2684 RB_CLEAR_NODE(&cfqq->p_node); 2685 INIT_LIST_HEAD(&cfqq->fifo); 2686 2687 atomic_set(&cfqq->ref, 0); 2688 cfqq->cfqd = cfqd; 2689 2690 cfq_mark_cfqq_prio_changed(cfqq); 2691 2692 if (is_sync) { 2693 if (!cfq_class_idle(cfqq)) 2694 cfq_mark_cfqq_idle_window(cfqq); 2695 cfq_mark_cfqq_sync(cfqq); 2696 } 2697 cfqq->pid = pid; 2698} 2699 2700#ifdef CONFIG_CFQ_GROUP_IOSCHED 2701static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) 2702{ 2703 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2704 struct cfq_data *cfqd = cic->key; 2705 unsigned long flags; 2706 struct request_queue *q; 2707 2708 if (unlikely(!cfqd)) 2709 return; 2710 2711 q = cfqd->queue; 2712 2713 spin_lock_irqsave(q->queue_lock, flags); 2714 2715 if (sync_cfqq) { 2716 /* 2717 * Drop reference to sync queue. A new sync queue will be 2718 * assigned in new group upon arrival of a fresh request. 2719 */ 2720 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2721 cic_set_cfqq(cic, NULL, 1); 2722 cfq_put_queue(sync_cfqq); 2723 } 2724 2725 spin_unlock_irqrestore(q->queue_lock, flags); 2726} 2727 2728static void cfq_ioc_set_cgroup(struct io_context *ioc) 2729{ 2730 call_for_each_cic(ioc, changed_cgroup); 2731 ioc->cgroup_changed = 0; 2732} 2733#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2734 2735static struct cfq_queue * 2736cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2737 struct io_context *ioc, gfp_t gfp_mask) 2738{ 2739 struct cfq_queue *cfqq, *new_cfqq = NULL; 2740 struct cfq_io_context *cic; 2741 struct cfq_group *cfqg; 2742 2743retry: 2744 cfqg = cfq_get_cfqg(cfqd, 1); 2745 cic = cfq_cic_lookup(cfqd, ioc); 2746 /* cic always exists here */ 2747 cfqq = cic_to_cfqq(cic, is_sync); 2748 2749 /* 2750 * Always try a new alloc if we fell back to the OOM cfqq 2751 * originally, since it should just be a temporary situation. 2752 */ 2753 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 2754 cfqq = NULL; 2755 if (new_cfqq) { 2756 cfqq = new_cfqq; 2757 new_cfqq = NULL; 2758 } else if (gfp_mask & __GFP_WAIT) { 2759 spin_unlock_irq(cfqd->queue->queue_lock); 2760 new_cfqq = kmem_cache_alloc_node(cfq_pool, 2761 gfp_mask | __GFP_ZERO, 2762 cfqd->queue->node); 2763 spin_lock_irq(cfqd->queue->queue_lock); 2764 if (new_cfqq) 2765 goto retry; 2766 } else { 2767 cfqq = kmem_cache_alloc_node(cfq_pool, 2768 gfp_mask | __GFP_ZERO, 2769 cfqd->queue->node); 2770 } 2771 2772 if (cfqq) { 2773 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 2774 cfq_init_prio_data(cfqq, ioc); 2775 cfq_link_cfqq_cfqg(cfqq, cfqg); 2776 cfq_log_cfqq(cfqd, cfqq, "alloced"); 2777 } else 2778 cfqq = &cfqd->oom_cfqq; 2779 } 2780 2781 if (new_cfqq) 2782 kmem_cache_free(cfq_pool, new_cfqq); 2783 2784 return cfqq; 2785} 2786 2787static struct cfq_queue ** 2788cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 2789{ 2790 switch (ioprio_class) { 2791 case IOPRIO_CLASS_RT: 2792 return &cfqd->async_cfqq[0][ioprio]; 2793 case IOPRIO_CLASS_BE: 2794 return &cfqd->async_cfqq[1][ioprio]; 2795 case IOPRIO_CLASS_IDLE: 2796 return &cfqd->async_idle_cfqq; 2797 default: 2798 BUG(); 2799 } 2800} 2801 2802static struct cfq_queue * 2803cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 2804 gfp_t gfp_mask) 2805{ 2806 const int ioprio = task_ioprio(ioc); 2807 const int ioprio_class = task_ioprio_class(ioc); 2808 struct cfq_queue **async_cfqq = NULL; 2809 struct cfq_queue *cfqq = NULL; 2810 2811 if (!is_sync) { 2812 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 2813 cfqq = *async_cfqq; 2814 } 2815 2816 if (!cfqq) 2817 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 2818 2819 /* 2820 * pin the queue now that it's allocated, scheduler exit will prune it 2821 */ 2822 if (!is_sync && !(*async_cfqq)) { 2823 atomic_inc(&cfqq->ref); 2824 *async_cfqq = cfqq; 2825 } 2826 2827 atomic_inc(&cfqq->ref); 2828 return cfqq; 2829} 2830 2831/* 2832 * We drop cfq io contexts lazily, so we may find a dead one. 2833 */ 2834static void 2835cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, 2836 struct cfq_io_context *cic) 2837{ 2838 unsigned long flags; 2839 2840 WARN_ON(!list_empty(&cic->queue_list)); 2841 2842 spin_lock_irqsave(&ioc->lock, flags); 2843 2844 BUG_ON(ioc->ioc_data == cic); 2845 2846 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); 2847 hlist_del_rcu(&cic->cic_list); 2848 spin_unlock_irqrestore(&ioc->lock, flags); 2849 2850 cfq_cic_free(cic); 2851} 2852 2853static struct cfq_io_context * 2854cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) 2855{ 2856 struct cfq_io_context *cic; 2857 unsigned long flags; 2858 void *k; 2859 2860 if (unlikely(!ioc)) 2861 return NULL; 2862 2863 rcu_read_lock(); 2864 2865 /* 2866 * we maintain a last-hit cache, to avoid browsing over the tree 2867 */ 2868 cic = rcu_dereference(ioc->ioc_data); 2869 if (cic && cic->key == cfqd) { 2870 rcu_read_unlock(); 2871 return cic; 2872 } 2873 2874 do { 2875 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); 2876 rcu_read_unlock(); 2877 if (!cic) 2878 break; 2879 /* ->key must be copied to avoid race with cfq_exit_queue() */ 2880 k = cic->key; 2881 if (unlikely(!k)) { 2882 cfq_drop_dead_cic(cfqd, ioc, cic); 2883 rcu_read_lock(); 2884 continue; 2885 } 2886 2887 spin_lock_irqsave(&ioc->lock, flags); 2888 rcu_assign_pointer(ioc->ioc_data, cic); 2889 spin_unlock_irqrestore(&ioc->lock, flags); 2890 break; 2891 } while (1); 2892 2893 return cic; 2894} 2895 2896/* 2897 * Add cic into ioc, using cfqd as the search key. This enables us to lookup 2898 * the process specific cfq io context when entered from the block layer. 2899 * Also adds the cic to a per-cfqd list, used when this queue is removed. 2900 */ 2901static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, 2902 struct cfq_io_context *cic, gfp_t gfp_mask) 2903{ 2904 unsigned long flags; 2905 int ret; 2906 2907 ret = radix_tree_preload(gfp_mask); 2908 if (!ret) { 2909 cic->ioc = ioc; 2910 cic->key = cfqd; 2911 2912 spin_lock_irqsave(&ioc->lock, flags); 2913 ret = radix_tree_insert(&ioc->radix_root, 2914 (unsigned long) cfqd, cic); 2915 if (!ret) 2916 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); 2917 spin_unlock_irqrestore(&ioc->lock, flags); 2918 2919 radix_tree_preload_end(); 2920 2921 if (!ret) { 2922 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2923 list_add(&cic->queue_list, &cfqd->cic_list); 2924 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2925 } 2926 } 2927 2928 if (ret) 2929 printk(KERN_ERR "cfq: cic link failed!\n"); 2930 2931 return ret; 2932} 2933 2934/* 2935 * Setup general io context and cfq io context. There can be several cfq 2936 * io contexts per general io context, if this process is doing io to more 2937 * than one device managed by cfq. 2938 */ 2939static struct cfq_io_context * 2940cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2941{ 2942 struct io_context *ioc = NULL; 2943 struct cfq_io_context *cic; 2944 2945 might_sleep_if(gfp_mask & __GFP_WAIT); 2946 2947 ioc = get_io_context(gfp_mask, cfqd->queue->node); 2948 if (!ioc) 2949 return NULL; 2950 2951 cic = cfq_cic_lookup(cfqd, ioc); 2952 if (cic) 2953 goto out; 2954 2955 cic = cfq_alloc_io_context(cfqd, gfp_mask); 2956 if (cic == NULL) 2957 goto err; 2958 2959 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) 2960 goto err_free; 2961 2962out: 2963 smp_read_barrier_depends(); 2964 if (unlikely(ioc->ioprio_changed)) 2965 cfq_ioc_set_ioprio(ioc); 2966 2967#ifdef CONFIG_CFQ_GROUP_IOSCHED 2968 if (unlikely(ioc->cgroup_changed)) 2969 cfq_ioc_set_cgroup(ioc); 2970#endif 2971 return cic; 2972err_free: 2973 cfq_cic_free(cic); 2974err: 2975 put_io_context(ioc); 2976 return NULL; 2977} 2978 2979static void 2980cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) 2981{ 2982 unsigned long elapsed = jiffies - cic->last_end_request; 2983 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); 2984 2985 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; 2986 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; 2987 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; 2988} 2989 2990static void 2991cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2992 struct request *rq) 2993{ 2994 sector_t sdist = 0; 2995 sector_t n_sec = blk_rq_sectors(rq); 2996 if (cfqq->last_request_pos) { 2997 if (cfqq->last_request_pos < blk_rq_pos(rq)) 2998 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 2999 else 3000 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3001 } 3002 3003 cfqq->seek_history <<= 1; 3004 if (blk_queue_nonrot(cfqd->queue)) 3005 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3006 else 3007 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3008} 3009 3010/* 3011 * Disable idle window if the process thinks too long or seeks so much that 3012 * it doesn't matter 3013 */ 3014static void 3015cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3016 struct cfq_io_context *cic) 3017{ 3018 int old_idle, enable_idle; 3019 3020 /* 3021 * Don't idle for async or idle io prio class 3022 */ 3023 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3024 return; 3025 3026 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3027 3028 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3029 cfq_mark_cfqq_deep(cfqq); 3030 3031 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || 3032 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3033 enable_idle = 0; 3034 else if (sample_valid(cic->ttime_samples)) { 3035 if (cic->ttime_mean > cfqd->cfq_slice_idle) 3036 enable_idle = 0; 3037 else 3038 enable_idle = 1; 3039 } 3040 3041 if (old_idle != enable_idle) { 3042 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3043 if (enable_idle) 3044 cfq_mark_cfqq_idle_window(cfqq); 3045 else 3046 cfq_clear_cfqq_idle_window(cfqq); 3047 } 3048} 3049 3050/* 3051 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3052 * no or if we aren't sure, a 1 will cause a preempt. 3053 */ 3054static bool 3055cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3056 struct request *rq) 3057{ 3058 struct cfq_queue *cfqq; 3059 3060 cfqq = cfqd->active_queue; 3061 if (!cfqq) 3062 return false; 3063 3064 if (cfq_class_idle(new_cfqq)) 3065 return false; 3066 3067 if (cfq_class_idle(cfqq)) 3068 return true; 3069 3070 /* 3071 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3072 */ 3073 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3074 return false; 3075 3076 /* 3077 * if the new request is sync, but the currently running queue is 3078 * not, let the sync request have priority. 3079 */ 3080 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3081 return true; 3082 3083 if (new_cfqq->cfqg != cfqq->cfqg) 3084 return false; 3085 3086 if (cfq_slice_used(cfqq)) 3087 return true; 3088 3089 /* Allow preemption only if we are idling on sync-noidle tree */ 3090 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3091 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3092 new_cfqq->service_tree->count == 2 && 3093 RB_EMPTY_ROOT(&cfqq->sort_list)) 3094 return true; 3095 3096 /* 3097 * So both queues are sync. Let the new request get disk time if 3098 * it's a metadata request and the current queue is doing regular IO. 3099 */ 3100 if (rq_is_meta(rq) && !cfqq->meta_pending) 3101 return true; 3102 3103 /* 3104 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3105 */ 3106 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3107 return true; 3108 3109 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3110 return false; 3111 3112 /* 3113 * if this request is as-good as one we would expect from the 3114 * current cfqq, let it preempt 3115 */ 3116 if (cfq_rq_close(cfqd, cfqq, rq)) 3117 return true; 3118 3119 return false; 3120} 3121 3122/* 3123 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3124 * let it have half of its nominal slice. 3125 */ 3126static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3127{ 3128 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3129 cfq_slice_expired(cfqd, 1); 3130 3131 /* 3132 * Put the new queue at the front of the of the current list, 3133 * so we know that it will be selected next. 3134 */ 3135 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3136 3137 cfq_service_tree_add(cfqd, cfqq, 1); 3138 3139 cfqq->slice_end = 0; 3140 cfq_mark_cfqq_slice_new(cfqq); 3141} 3142 3143/* 3144 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3145 * something we should do about it 3146 */ 3147static void 3148cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3149 struct request *rq) 3150{ 3151 struct cfq_io_context *cic = RQ_CIC(rq); 3152 3153 cfqd->rq_queued++; 3154 if (rq_is_meta(rq)) 3155 cfqq->meta_pending++; 3156 3157 cfq_update_io_thinktime(cfqd, cic); 3158 cfq_update_io_seektime(cfqd, cfqq, rq); 3159 cfq_update_idle_window(cfqd, cfqq, cic); 3160 3161 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3162 3163 if (cfqq == cfqd->active_queue) { 3164 /* 3165 * Remember that we saw a request from this process, but 3166 * don't start queuing just yet. Otherwise we risk seeing lots 3167 * of tiny requests, because we disrupt the normal plugging 3168 * and merging. If the request is already larger than a single 3169 * page, let it rip immediately. For that case we assume that 3170 * merging is already done. Ditto for a busy system that 3171 * has other work pending, don't risk delaying until the 3172 * idle timer unplug to continue working. 3173 */ 3174 if (cfq_cfqq_wait_request(cfqq)) { 3175 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3176 cfqd->busy_queues > 1) { 3177 del_timer(&cfqd->idle_slice_timer); 3178 cfq_clear_cfqq_wait_request(cfqq); 3179 __blk_run_queue(cfqd->queue); 3180 } else 3181 cfq_mark_cfqq_must_dispatch(cfqq); 3182 } 3183 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3184 /* 3185 * not the active queue - expire current slice if it is 3186 * idle and has expired it's mean thinktime or this new queue 3187 * has some old slice time left and is of higher priority or 3188 * this new queue is RT and the current one is BE 3189 */ 3190 cfq_preempt_queue(cfqd, cfqq); 3191 __blk_run_queue(cfqd->queue); 3192 } 3193} 3194 3195static void cfq_insert_request(struct request_queue *q, struct request *rq) 3196{ 3197 struct cfq_data *cfqd = q->elevator->elevator_data; 3198 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3199 3200 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3201 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); 3202 3203 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3204 list_add_tail(&rq->queuelist, &cfqq->fifo); 3205 cfq_add_rq_rb(rq); 3206 3207 cfq_rq_enqueued(cfqd, cfqq, rq); 3208} 3209 3210/* 3211 * Update hw_tag based on peak queue depth over 50 samples under 3212 * sufficient load. 3213 */ 3214static void cfq_update_hw_tag(struct cfq_data *cfqd) 3215{ 3216 struct cfq_queue *cfqq = cfqd->active_queue; 3217 3218 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3219 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3220 3221 if (cfqd->hw_tag == 1) 3222 return; 3223 3224 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3225 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3226 return; 3227 3228 /* 3229 * If active queue hasn't enough requests and can idle, cfq might not 3230 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3231 * case 3232 */ 3233 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3234 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3235 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3236 return; 3237 3238 if (cfqd->hw_tag_samples++ < 50) 3239 return; 3240 3241 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3242 cfqd->hw_tag = 1; 3243 else 3244 cfqd->hw_tag = 0; 3245} 3246 3247static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3248{ 3249 struct cfq_io_context *cic = cfqd->active_cic; 3250 3251 /* If there are other queues in the group, don't wait */ 3252 if (cfqq->cfqg->nr_cfqq > 1) 3253 return false; 3254 3255 if (cfq_slice_used(cfqq)) 3256 return true; 3257 3258 /* if slice left is less than think time, wait busy */ 3259 if (cic && sample_valid(cic->ttime_samples) 3260 && (cfqq->slice_end - jiffies < cic->ttime_mean)) 3261 return true; 3262 3263 /* 3264 * If think times is less than a jiffy than ttime_mean=0 and above 3265 * will not be true. It might happen that slice has not expired yet 3266 * but will expire soon (4-5 ns) during select_queue(). To cover the 3267 * case where think time is less than a jiffy, mark the queue wait 3268 * busy if only 1 jiffy is left in the slice. 3269 */ 3270 if (cfqq->slice_end - jiffies == 1) 3271 return true; 3272 3273 return false; 3274} 3275 3276static void cfq_completed_request(struct request_queue *q, struct request *rq) 3277{ 3278 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3279 struct cfq_data *cfqd = cfqq->cfqd; 3280 const int sync = rq_is_sync(rq); 3281 unsigned long now; 3282 3283 now = jiffies; 3284 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq)); 3285 3286 cfq_update_hw_tag(cfqd); 3287 3288 WARN_ON(!cfqd->rq_in_driver); 3289 WARN_ON(!cfqq->dispatched); 3290 cfqd->rq_in_driver--; 3291 cfqq->dispatched--; 3292 3293 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3294 3295 if (sync) { 3296 RQ_CIC(rq)->last_end_request = now; 3297 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3298 cfqd->last_delayed_sync = now; 3299 } 3300 3301 /* 3302 * If this is the active queue, check if it needs to be expired, 3303 * or if we want to idle in case it has no pending requests. 3304 */ 3305 if (cfqd->active_queue == cfqq) { 3306 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3307 3308 if (cfq_cfqq_slice_new(cfqq)) { 3309 cfq_set_prio_slice(cfqd, cfqq); 3310 cfq_clear_cfqq_slice_new(cfqq); 3311 } 3312 3313 /* 3314 * Should we wait for next request to come in before we expire 3315 * the queue. 3316 */ 3317 if (cfq_should_wait_busy(cfqd, cfqq)) { 3318 cfqq->slice_end = jiffies + cfqd->cfq_slice_idle; 3319 cfq_mark_cfqq_wait_busy(cfqq); 3320 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3321 } 3322 3323 /* 3324 * Idling is not enabled on: 3325 * - expired queues 3326 * - idle-priority queues 3327 * - async queues 3328 * - queues with still some requests queued 3329 * - when there is a close cooperator 3330 */ 3331 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3332 cfq_slice_expired(cfqd, 1); 3333 else if (sync && cfqq_empty && 3334 !cfq_close_cooperator(cfqd, cfqq)) { 3335 cfqd->noidle_tree_requires_idle |= !rq_noidle(rq); 3336 /* 3337 * Idling is enabled for SYNC_WORKLOAD. 3338 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree 3339 * only if we processed at least one !rq_noidle request 3340 */ 3341 if (cfqd->serving_type == SYNC_WORKLOAD 3342 || cfqd->noidle_tree_requires_idle 3343 || cfqq->cfqg->nr_cfqq == 1) 3344 cfq_arm_slice_timer(cfqd); 3345 } 3346 } 3347 3348 if (!cfqd->rq_in_driver) 3349 cfq_schedule_dispatch(cfqd); 3350} 3351 3352/* 3353 * we temporarily boost lower priority queues if they are holding fs exclusive 3354 * resources. they are boosted to normal prio (CLASS_BE/4) 3355 */ 3356static void cfq_prio_boost(struct cfq_queue *cfqq) 3357{ 3358 if (has_fs_excl()) { 3359 /* 3360 * boost idle prio on transactions that would lock out other 3361 * users of the filesystem 3362 */ 3363 if (cfq_class_idle(cfqq)) 3364 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3365 if (cfqq->ioprio > IOPRIO_NORM) 3366 cfqq->ioprio = IOPRIO_NORM; 3367 } else { 3368 /* 3369 * unboost the queue (if needed) 3370 */ 3371 cfqq->ioprio_class = cfqq->org_ioprio_class; 3372 cfqq->ioprio = cfqq->org_ioprio; 3373 } 3374} 3375 3376static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3377{ 3378 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3379 cfq_mark_cfqq_must_alloc_slice(cfqq); 3380 return ELV_MQUEUE_MUST; 3381 } 3382 3383 return ELV_MQUEUE_MAY; 3384} 3385 3386static int cfq_may_queue(struct request_queue *q, int rw) 3387{ 3388 struct cfq_data *cfqd = q->elevator->elevator_data; 3389 struct task_struct *tsk = current; 3390 struct cfq_io_context *cic; 3391 struct cfq_queue *cfqq; 3392 3393 /* 3394 * don't force setup of a queue from here, as a call to may_queue 3395 * does not necessarily imply that a request actually will be queued. 3396 * so just lookup a possibly existing queue, or return 'may queue' 3397 * if that fails 3398 */ 3399 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3400 if (!cic) 3401 return ELV_MQUEUE_MAY; 3402 3403 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3404 if (cfqq) { 3405 cfq_init_prio_data(cfqq, cic->ioc); 3406 cfq_prio_boost(cfqq); 3407 3408 return __cfq_may_queue(cfqq); 3409 } 3410 3411 return ELV_MQUEUE_MAY; 3412} 3413 3414/* 3415 * queue lock held here 3416 */ 3417static void cfq_put_request(struct request *rq) 3418{ 3419 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3420 3421 if (cfqq) { 3422 const int rw = rq_data_dir(rq); 3423 3424 BUG_ON(!cfqq->allocated[rw]); 3425 cfqq->allocated[rw]--; 3426 3427 put_io_context(RQ_CIC(rq)->ioc); 3428 3429 rq->elevator_private = NULL; 3430 rq->elevator_private2 = NULL; 3431 3432 cfq_put_queue(cfqq); 3433 } 3434} 3435 3436static struct cfq_queue * 3437cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, 3438 struct cfq_queue *cfqq) 3439{ 3440 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3441 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3442 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3443 cfq_put_queue(cfqq); 3444 return cic_to_cfqq(cic, 1); 3445} 3446 3447/* 3448 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3449 * was the last process referring to said cfqq. 3450 */ 3451static struct cfq_queue * 3452split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) 3453{ 3454 if (cfqq_process_refs(cfqq) == 1) { 3455 cfqq->pid = current->pid; 3456 cfq_clear_cfqq_coop(cfqq); 3457 cfq_clear_cfqq_split_coop(cfqq); 3458 return cfqq; 3459 } 3460 3461 cic_set_cfqq(cic, NULL, 1); 3462 cfq_put_queue(cfqq); 3463 return NULL; 3464} 3465/* 3466 * Allocate cfq data structures associated with this request. 3467 */ 3468static int 3469cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3470{ 3471 struct cfq_data *cfqd = q->elevator->elevator_data; 3472 struct cfq_io_context *cic; 3473 const int rw = rq_data_dir(rq); 3474 const bool is_sync = rq_is_sync(rq); 3475 struct cfq_queue *cfqq; 3476 unsigned long flags; 3477 3478 might_sleep_if(gfp_mask & __GFP_WAIT); 3479 3480 cic = cfq_get_io_context(cfqd, gfp_mask); 3481 3482 spin_lock_irqsave(q->queue_lock, flags); 3483 3484 if (!cic) 3485 goto queue_fail; 3486 3487new_queue: 3488 cfqq = cic_to_cfqq(cic, is_sync); 3489 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3490 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); 3491 cic_set_cfqq(cic, cfqq, is_sync); 3492 } else { 3493 /* 3494 * If the queue was seeky for too long, break it apart. 3495 */ 3496 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3497 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3498 cfqq = split_cfqq(cic, cfqq); 3499 if (!cfqq) 3500 goto new_queue; 3501 } 3502 3503 /* 3504 * Check to see if this queue is scheduled to merge with 3505 * another, closely cooperating queue. The merging of 3506 * queues happens here as it must be done in process context. 3507 * The reference on new_cfqq was taken in merge_cfqqs. 3508 */ 3509 if (cfqq->new_cfqq) 3510 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3511 } 3512 3513 cfqq->allocated[rw]++; 3514 atomic_inc(&cfqq->ref); 3515 3516 spin_unlock_irqrestore(q->queue_lock, flags); 3517 3518 rq->elevator_private = cic; 3519 rq->elevator_private2 = cfqq; 3520 return 0; 3521 3522queue_fail: 3523 if (cic) 3524 put_io_context(cic->ioc); 3525 3526 cfq_schedule_dispatch(cfqd); 3527 spin_unlock_irqrestore(q->queue_lock, flags); 3528 cfq_log(cfqd, "set_request fail"); 3529 return 1; 3530} 3531 3532static void cfq_kick_queue(struct work_struct *work) 3533{ 3534 struct cfq_data *cfqd = 3535 container_of(work, struct cfq_data, unplug_work); 3536 struct request_queue *q = cfqd->queue; 3537 3538 spin_lock_irq(q->queue_lock); 3539 __blk_run_queue(cfqd->queue); 3540 spin_unlock_irq(q->queue_lock); 3541} 3542 3543/* 3544 * Timer running if the active_queue is currently idling inside its time slice 3545 */ 3546static void cfq_idle_slice_timer(unsigned long data) 3547{ 3548 struct cfq_data *cfqd = (struct cfq_data *) data; 3549 struct cfq_queue *cfqq; 3550 unsigned long flags; 3551 int timed_out = 1; 3552 3553 cfq_log(cfqd, "idle timer fired"); 3554 3555 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3556 3557 cfqq = cfqd->active_queue; 3558 if (cfqq) { 3559 timed_out = 0; 3560 3561 /* 3562 * We saw a request before the queue expired, let it through 3563 */ 3564 if (cfq_cfqq_must_dispatch(cfqq)) 3565 goto out_kick; 3566 3567 /* 3568 * expired 3569 */ 3570 if (cfq_slice_used(cfqq)) 3571 goto expire; 3572 3573 /* 3574 * only expire and reinvoke request handler, if there are 3575 * other queues with pending requests 3576 */ 3577 if (!cfqd->busy_queues) 3578 goto out_cont; 3579 3580 /* 3581 * not expired and it has a request pending, let it dispatch 3582 */ 3583 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3584 goto out_kick; 3585 3586 /* 3587 * Queue depth flag is reset only when the idle didn't succeed 3588 */ 3589 cfq_clear_cfqq_deep(cfqq); 3590 } 3591expire: 3592 cfq_slice_expired(cfqd, timed_out); 3593out_kick: 3594 cfq_schedule_dispatch(cfqd); 3595out_cont: 3596 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3597} 3598 3599static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3600{ 3601 del_timer_sync(&cfqd->idle_slice_timer); 3602 cancel_work_sync(&cfqd->unplug_work); 3603} 3604 3605static void cfq_put_async_queues(struct cfq_data *cfqd) 3606{ 3607 int i; 3608 3609 for (i = 0; i < IOPRIO_BE_NR; i++) { 3610 if (cfqd->async_cfqq[0][i]) 3611 cfq_put_queue(cfqd->async_cfqq[0][i]); 3612 if (cfqd->async_cfqq[1][i]) 3613 cfq_put_queue(cfqd->async_cfqq[1][i]); 3614 } 3615 3616 if (cfqd->async_idle_cfqq) 3617 cfq_put_queue(cfqd->async_idle_cfqq); 3618} 3619 3620static void cfq_cfqd_free(struct rcu_head *head) 3621{ 3622 kfree(container_of(head, struct cfq_data, rcu)); 3623} 3624 3625static void cfq_exit_queue(struct elevator_queue *e) 3626{ 3627 struct cfq_data *cfqd = e->elevator_data; 3628 struct request_queue *q = cfqd->queue; 3629 3630 cfq_shutdown_timer_wq(cfqd); 3631 3632 spin_lock_irq(q->queue_lock); 3633 3634 if (cfqd->active_queue) 3635 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3636 3637 while (!list_empty(&cfqd->cic_list)) { 3638 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, 3639 struct cfq_io_context, 3640 queue_list); 3641 3642 __cfq_exit_single_io_context(cfqd, cic); 3643 } 3644 3645 cfq_put_async_queues(cfqd); 3646 cfq_release_cfq_groups(cfqd); 3647 blkiocg_del_blkio_group(&cfqd->root_group.blkg); 3648 3649 spin_unlock_irq(q->queue_lock); 3650 3651 cfq_shutdown_timer_wq(cfqd); 3652 3653 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */ 3654 call_rcu(&cfqd->rcu, cfq_cfqd_free); 3655} 3656 3657static void *cfq_init_queue(struct request_queue *q) 3658{ 3659 struct cfq_data *cfqd; 3660 int i, j; 3661 struct cfq_group *cfqg; 3662 struct cfq_rb_root *st; 3663 3664 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3665 if (!cfqd) 3666 return NULL; 3667 3668 /* Init root service tree */ 3669 cfqd->grp_service_tree = CFQ_RB_ROOT; 3670 3671 /* Init root group */ 3672 cfqg = &cfqd->root_group; 3673 for_each_cfqg_st(cfqg, i, j, st) 3674 *st = CFQ_RB_ROOT; 3675 RB_CLEAR_NODE(&cfqg->rb_node); 3676 3677 /* Give preference to root group over other groups */ 3678 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 3679 3680#ifdef CONFIG_CFQ_GROUP_IOSCHED 3681 /* 3682 * Take a reference to root group which we never drop. This is just 3683 * to make sure that cfq_put_cfqg() does not try to kfree root group 3684 */ 3685 atomic_set(&cfqg->ref, 1); 3686 blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd, 3687 0); 3688#endif 3689 /* 3690 * Not strictly needed (since RB_ROOT just clears the node and we 3691 * zeroed cfqd on alloc), but better be safe in case someone decides 3692 * to add magic to the rb code 3693 */ 3694 for (i = 0; i < CFQ_PRIO_LISTS; i++) 3695 cfqd->prio_trees[i] = RB_ROOT; 3696 3697 /* 3698 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 3699 * Grab a permanent reference to it, so that the normal code flow 3700 * will not attempt to free it. 3701 */ 3702 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 3703 atomic_inc(&cfqd->oom_cfqq.ref); 3704 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 3705 3706 INIT_LIST_HEAD(&cfqd->cic_list); 3707 3708 cfqd->queue = q; 3709 3710 init_timer(&cfqd->idle_slice_timer); 3711 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 3712 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 3713 3714 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 3715 3716 cfqd->cfq_quantum = cfq_quantum; 3717 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 3718 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 3719 cfqd->cfq_back_max = cfq_back_max; 3720 cfqd->cfq_back_penalty = cfq_back_penalty; 3721 cfqd->cfq_slice[0] = cfq_slice_async; 3722 cfqd->cfq_slice[1] = cfq_slice_sync; 3723 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 3724 cfqd->cfq_slice_idle = cfq_slice_idle; 3725 cfqd->cfq_latency = 1; 3726 cfqd->cfq_group_isolation = 0; 3727 cfqd->hw_tag = -1; 3728 /* 3729 * we optimistically start assuming sync ops weren't delayed in last 3730 * second, in order to have larger depth for async operations. 3731 */ 3732 cfqd->last_delayed_sync = jiffies - HZ; 3733 INIT_RCU_HEAD(&cfqd->rcu); 3734 return cfqd; 3735} 3736 3737static void cfq_slab_kill(void) 3738{ 3739 /* 3740 * Caller already ensured that pending RCU callbacks are completed, 3741 * so we should have no busy allocations at this point. 3742 */ 3743 if (cfq_pool) 3744 kmem_cache_destroy(cfq_pool); 3745 if (cfq_ioc_pool) 3746 kmem_cache_destroy(cfq_ioc_pool); 3747} 3748 3749static int __init cfq_slab_setup(void) 3750{ 3751 cfq_pool = KMEM_CACHE(cfq_queue, 0); 3752 if (!cfq_pool) 3753 goto fail; 3754 3755 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); 3756 if (!cfq_ioc_pool) 3757 goto fail; 3758 3759 return 0; 3760fail: 3761 cfq_slab_kill(); 3762 return -ENOMEM; 3763} 3764 3765/* 3766 * sysfs parts below --> 3767 */ 3768static ssize_t 3769cfq_var_show(unsigned int var, char *page) 3770{ 3771 return sprintf(page, "%d\n", var); 3772} 3773 3774static ssize_t 3775cfq_var_store(unsigned int *var, const char *page, size_t count) 3776{ 3777 char *p = (char *) page; 3778 3779 *var = simple_strtoul(p, &p, 10); 3780 return count; 3781} 3782 3783#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 3784static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 3785{ \ 3786 struct cfq_data *cfqd = e->elevator_data; \ 3787 unsigned int __data = __VAR; \ 3788 if (__CONV) \ 3789 __data = jiffies_to_msecs(__data); \ 3790 return cfq_var_show(__data, (page)); \ 3791} 3792SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 3793SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 3794SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 3795SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 3796SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 3797SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 3798SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 3799SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 3800SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 3801SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 3802SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0); 3803#undef SHOW_FUNCTION 3804 3805#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 3806static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 3807{ \ 3808 struct cfq_data *cfqd = e->elevator_data; \ 3809 unsigned int __data; \ 3810 int ret = cfq_var_store(&__data, (page), count); \ 3811 if (__data < (MIN)) \ 3812 __data = (MIN); \ 3813 else if (__data > (MAX)) \ 3814 __data = (MAX); \ 3815 if (__CONV) \ 3816 *(__PTR) = msecs_to_jiffies(__data); \ 3817 else \ 3818 *(__PTR) = __data; \ 3819 return ret; \ 3820} 3821STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 3822STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 3823 UINT_MAX, 1); 3824STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 3825 UINT_MAX, 1); 3826STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 3827STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 3828 UINT_MAX, 0); 3829STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 3830STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 3831STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 3832STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 3833 UINT_MAX, 0); 3834STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 3835STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0); 3836#undef STORE_FUNCTION 3837 3838#define CFQ_ATTR(name) \ 3839 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 3840 3841static struct elv_fs_entry cfq_attrs[] = { 3842 CFQ_ATTR(quantum), 3843 CFQ_ATTR(fifo_expire_sync), 3844 CFQ_ATTR(fifo_expire_async), 3845 CFQ_ATTR(back_seek_max), 3846 CFQ_ATTR(back_seek_penalty), 3847 CFQ_ATTR(slice_sync), 3848 CFQ_ATTR(slice_async), 3849 CFQ_ATTR(slice_async_rq), 3850 CFQ_ATTR(slice_idle), 3851 CFQ_ATTR(low_latency), 3852 CFQ_ATTR(group_isolation), 3853 __ATTR_NULL 3854}; 3855 3856static struct elevator_type iosched_cfq = { 3857 .ops = { 3858 .elevator_merge_fn = cfq_merge, 3859 .elevator_merged_fn = cfq_merged_request, 3860 .elevator_merge_req_fn = cfq_merged_requests, 3861 .elevator_allow_merge_fn = cfq_allow_merge, 3862 .elevator_dispatch_fn = cfq_dispatch_requests, 3863 .elevator_add_req_fn = cfq_insert_request, 3864 .elevator_activate_req_fn = cfq_activate_request, 3865 .elevator_deactivate_req_fn = cfq_deactivate_request, 3866 .elevator_queue_empty_fn = cfq_queue_empty, 3867 .elevator_completed_req_fn = cfq_completed_request, 3868 .elevator_former_req_fn = elv_rb_former_request, 3869 .elevator_latter_req_fn = elv_rb_latter_request, 3870 .elevator_set_req_fn = cfq_set_request, 3871 .elevator_put_req_fn = cfq_put_request, 3872 .elevator_may_queue_fn = cfq_may_queue, 3873 .elevator_init_fn = cfq_init_queue, 3874 .elevator_exit_fn = cfq_exit_queue, 3875 .trim = cfq_free_io_context, 3876 }, 3877 .elevator_attrs = cfq_attrs, 3878 .elevator_name = "cfq", 3879 .elevator_owner = THIS_MODULE, 3880}; 3881 3882#ifdef CONFIG_CFQ_GROUP_IOSCHED 3883static struct blkio_policy_type blkio_policy_cfq = { 3884 .ops = { 3885 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 3886 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 3887 }, 3888}; 3889#else 3890static struct blkio_policy_type blkio_policy_cfq; 3891#endif 3892 3893static int __init cfq_init(void) 3894{ 3895 /* 3896 * could be 0 on HZ < 1000 setups 3897 */ 3898 if (!cfq_slice_async) 3899 cfq_slice_async = 1; 3900 if (!cfq_slice_idle) 3901 cfq_slice_idle = 1; 3902 3903 if (cfq_slab_setup()) 3904 return -ENOMEM; 3905 3906 elv_register(&iosched_cfq); 3907 blkio_policy_register(&blkio_policy_cfq); 3908 3909 return 0; 3910} 3911 3912static void __exit cfq_exit(void) 3913{ 3914 DECLARE_COMPLETION_ONSTACK(all_gone); 3915 blkio_policy_unregister(&blkio_policy_cfq); 3916 elv_unregister(&iosched_cfq); 3917 ioc_gone = &all_gone; 3918 /* ioc_gone's update must be visible before reading ioc_count */ 3919 smp_wmb(); 3920 3921 /* 3922 * this also protects us from entering cfq_slab_kill() with 3923 * pending RCU callbacks 3924 */ 3925 if (elv_ioc_count_read(cfq_ioc_count)) 3926 wait_for_completion(&all_gone); 3927 cfq_slab_kill(); 3928} 3929 3930module_init(cfq_init); 3931module_exit(cfq_exit); 3932 3933MODULE_AUTHOR("Jens Axboe"); 3934MODULE_LICENSE("GPL"); 3935MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 3936