cfq-iosched.c revision afc24d49c1e5dbeef745c1c1246f5ae6ebd97c71
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/slab.h> 11#include <linux/blkdev.h> 12#include <linux/elevator.h> 13#include <linux/jiffies.h> 14#include <linux/rbtree.h> 15#include <linux/ioprio.h> 16#include <linux/blktrace_api.h> 17#include "blk-cgroup.h" 18 19/* 20 * tunables 21 */ 22/* max queue in one round of service */ 23static const int cfq_quantum = 8; 24static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 25/* maximum backwards seek, in KiB */ 26static const int cfq_back_max = 16 * 1024; 27/* penalty of a backwards seek */ 28static const int cfq_back_penalty = 2; 29static const int cfq_slice_sync = HZ / 10; 30static int cfq_slice_async = HZ / 25; 31static const int cfq_slice_async_rq = 2; 32static int cfq_slice_idle = HZ / 125; 33static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 34static const int cfq_hist_divisor = 4; 35 36/* 37 * offset from end of service tree 38 */ 39#define CFQ_IDLE_DELAY (HZ / 5) 40 41/* 42 * below this threshold, we consider thinktime immediate 43 */ 44#define CFQ_MIN_TT (2) 45 46#define CFQ_SLICE_SCALE (5) 47#define CFQ_HW_QUEUE_MIN (5) 48#define CFQ_SERVICE_SHIFT 12 49 50#define CFQQ_SEEK_THR (sector_t)(8 * 100) 51#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 52#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 53#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 54 55#define RQ_CIC(rq) \ 56 ((struct cfq_io_context *) (rq)->elevator_private) 57#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) 58#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3) 59 60static struct kmem_cache *cfq_pool; 61static struct kmem_cache *cfq_ioc_pool; 62 63static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); 64static struct completion *ioc_gone; 65static DEFINE_SPINLOCK(ioc_gone_lock); 66 67#define CFQ_PRIO_LISTS IOPRIO_BE_NR 68#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 69#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 70 71#define sample_valid(samples) ((samples) > 80) 72#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 73 74/* 75 * Most of our rbtree usage is for sorting with min extraction, so 76 * if we cache the leftmost node we don't have to walk down the tree 77 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 78 * move this into the elevator for the rq sorting as well. 79 */ 80struct cfq_rb_root { 81 struct rb_root rb; 82 struct rb_node *left; 83 unsigned count; 84 unsigned total_weight; 85 u64 min_vdisktime; 86 struct rb_node *active; 87}; 88#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ 89 .count = 0, .min_vdisktime = 0, } 90 91/* 92 * Per process-grouping structure 93 */ 94struct cfq_queue { 95 /* reference count */ 96 atomic_t ref; 97 /* various state flags, see below */ 98 unsigned int flags; 99 /* parent cfq_data */ 100 struct cfq_data *cfqd; 101 /* service_tree member */ 102 struct rb_node rb_node; 103 /* service_tree key */ 104 unsigned long rb_key; 105 /* prio tree member */ 106 struct rb_node p_node; 107 /* prio tree root we belong to, if any */ 108 struct rb_root *p_root; 109 /* sorted list of pending requests */ 110 struct rb_root sort_list; 111 /* if fifo isn't expired, next request to serve */ 112 struct request *next_rq; 113 /* requests queued in sort_list */ 114 int queued[2]; 115 /* currently allocated requests */ 116 int allocated[2]; 117 /* fifo list of requests in sort_list */ 118 struct list_head fifo; 119 120 /* time when queue got scheduled in to dispatch first request. */ 121 unsigned long dispatch_start; 122 unsigned int allocated_slice; 123 unsigned int slice_dispatch; 124 /* time when first request from queue completed and slice started. */ 125 unsigned long slice_start; 126 unsigned long slice_end; 127 long slice_resid; 128 129 /* pending metadata requests */ 130 int meta_pending; 131 /* number of requests that are on the dispatch list or inside driver */ 132 int dispatched; 133 134 /* io prio of this group */ 135 unsigned short ioprio, org_ioprio; 136 unsigned short ioprio_class, org_ioprio_class; 137 138 pid_t pid; 139 140 u32 seek_history; 141 sector_t last_request_pos; 142 143 struct cfq_rb_root *service_tree; 144 struct cfq_queue *new_cfqq; 145 struct cfq_group *cfqg; 146 struct cfq_group *orig_cfqg; 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_CFQ_GROUP_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_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", slice_used); 887 return slice_used; 888} 889 890static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 891 struct cfq_queue *cfqq) 892{ 893 struct cfq_rb_root *st = &cfqd->grp_service_tree; 894 unsigned int used_sl, charge_sl; 895 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 896 - cfqg->service_tree_idle.count; 897 898 BUG_ON(nr_sync < 0); 899 used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq); 900 901 if (!cfq_cfqq_sync(cfqq) && !nr_sync) 902 charge_sl = cfqq->allocated_slice; 903 904 /* Can't update vdisktime while group is on service tree */ 905 cfq_rb_erase(&cfqg->rb_node, st); 906 cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg); 907 __cfq_group_service_tree_add(st, cfqg); 908 909 /* This group is being expired. Save the context */ 910 if (time_after(cfqd->workload_expires, jiffies)) { 911 cfqg->saved_workload_slice = cfqd->workload_expires 912 - jiffies; 913 cfqg->saved_workload = cfqd->serving_type; 914 cfqg->saved_serving_prio = cfqd->serving_prio; 915 } else 916 cfqg->saved_workload_slice = 0; 917 918 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 919 st->min_vdisktime); 920 blkiocg_update_timeslice_used(&cfqg->blkg, used_sl); 921 blkiocg_set_start_empty_time(&cfqg->blkg); 922} 923 924#ifdef CONFIG_CFQ_GROUP_IOSCHED 925static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 926{ 927 if (blkg) 928 return container_of(blkg, struct cfq_group, blkg); 929 return NULL; 930} 931 932void 933cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight) 934{ 935 cfqg_of_blkg(blkg)->weight = weight; 936} 937 938static struct cfq_group * 939cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) 940{ 941 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); 942 struct cfq_group *cfqg = NULL; 943 void *key = cfqd; 944 int i, j; 945 struct cfq_rb_root *st; 946 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 947 unsigned int major, minor; 948 949 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); 950 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { 951 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 952 cfqg->blkg.dev = MKDEV(major, minor); 953 goto done; 954 } 955 if (cfqg || !create) 956 goto done; 957 958 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 959 if (!cfqg) 960 goto done; 961 962 for_each_cfqg_st(cfqg, i, j, st) 963 *st = CFQ_RB_ROOT; 964 RB_CLEAR_NODE(&cfqg->rb_node); 965 966 /* 967 * Take the initial reference that will be released on destroy 968 * This can be thought of a joint reference by cgroup and 969 * elevator which will be dropped by either elevator exit 970 * or cgroup deletion path depending on who is exiting first. 971 */ 972 atomic_set(&cfqg->ref, 1); 973 974 /* Add group onto cgroup list */ 975 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 976 blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, 977 MKDEV(major, minor)); 978 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); 979 980 /* Add group on cfqd list */ 981 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 982 983done: 984 return cfqg; 985} 986 987/* 988 * Search for the cfq group current task belongs to. If create = 1, then also 989 * create the cfq group if it does not exist. request_queue lock must be held. 990 */ 991static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) 992{ 993 struct cgroup *cgroup; 994 struct cfq_group *cfqg = NULL; 995 996 rcu_read_lock(); 997 cgroup = task_cgroup(current, blkio_subsys_id); 998 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create); 999 if (!cfqg && create) 1000 cfqg = &cfqd->root_group; 1001 rcu_read_unlock(); 1002 return cfqg; 1003} 1004 1005static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1006{ 1007 atomic_inc(&cfqg->ref); 1008 return cfqg; 1009} 1010 1011static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1012{ 1013 /* Currently, all async queues are mapped to root group */ 1014 if (!cfq_cfqq_sync(cfqq)) 1015 cfqg = &cfqq->cfqd->root_group; 1016 1017 cfqq->cfqg = cfqg; 1018 /* cfqq reference on cfqg */ 1019 atomic_inc(&cfqq->cfqg->ref); 1020} 1021 1022static void cfq_put_cfqg(struct cfq_group *cfqg) 1023{ 1024 struct cfq_rb_root *st; 1025 int i, j; 1026 1027 BUG_ON(atomic_read(&cfqg->ref) <= 0); 1028 if (!atomic_dec_and_test(&cfqg->ref)) 1029 return; 1030 for_each_cfqg_st(cfqg, i, j, st) 1031 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL); 1032 kfree(cfqg); 1033} 1034 1035static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1036{ 1037 /* Something wrong if we are trying to remove same group twice */ 1038 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1039 1040 hlist_del_init(&cfqg->cfqd_node); 1041 1042 /* 1043 * Put the reference taken at the time of creation so that when all 1044 * queues are gone, group can be destroyed. 1045 */ 1046 cfq_put_cfqg(cfqg); 1047} 1048 1049static void cfq_release_cfq_groups(struct cfq_data *cfqd) 1050{ 1051 struct hlist_node *pos, *n; 1052 struct cfq_group *cfqg; 1053 1054 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1055 /* 1056 * If cgroup removal path got to blk_group first and removed 1057 * it from cgroup list, then it will take care of destroying 1058 * cfqg also. 1059 */ 1060 if (!blkiocg_del_blkio_group(&cfqg->blkg)) 1061 cfq_destroy_cfqg(cfqd, cfqg); 1062 } 1063} 1064 1065/* 1066 * Blk cgroup controller notification saying that blkio_group object is being 1067 * delinked as associated cgroup object is going away. That also means that 1068 * no new IO will come in this group. So get rid of this group as soon as 1069 * any pending IO in the group is finished. 1070 * 1071 * This function is called under rcu_read_lock(). key is the rcu protected 1072 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu 1073 * read lock. 1074 * 1075 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means 1076 * it should not be NULL as even if elevator was exiting, cgroup deltion 1077 * path got to it first. 1078 */ 1079void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) 1080{ 1081 unsigned long flags; 1082 struct cfq_data *cfqd = key; 1083 1084 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 1085 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1086 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 1087} 1088 1089#else /* GROUP_IOSCHED */ 1090static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) 1091{ 1092 return &cfqd->root_group; 1093} 1094 1095static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1096{ 1097 return NULL; 1098} 1099 1100static inline void 1101cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1102 cfqq->cfqg = cfqg; 1103} 1104 1105static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1106static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1107 1108#endif /* GROUP_IOSCHED */ 1109 1110/* 1111 * The cfqd->service_trees holds all pending cfq_queue's that have 1112 * requests waiting to be processed. It is sorted in the order that 1113 * we will service the queues. 1114 */ 1115static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1116 bool add_front) 1117{ 1118 struct rb_node **p, *parent; 1119 struct cfq_queue *__cfqq; 1120 unsigned long rb_key; 1121 struct cfq_rb_root *service_tree; 1122 int left; 1123 int new_cfqq = 1; 1124 int group_changed = 0; 1125 1126#ifdef CONFIG_CFQ_GROUP_IOSCHED 1127 if (!cfqd->cfq_group_isolation 1128 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD 1129 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) { 1130 /* Move this cfq to root group */ 1131 cfq_log_cfqq(cfqd, cfqq, "moving to root group"); 1132 if (!RB_EMPTY_NODE(&cfqq->rb_node)) 1133 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1134 cfqq->orig_cfqg = cfqq->cfqg; 1135 cfqq->cfqg = &cfqd->root_group; 1136 atomic_inc(&cfqd->root_group.ref); 1137 group_changed = 1; 1138 } else if (!cfqd->cfq_group_isolation 1139 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) { 1140 /* cfqq is sequential now needs to go to its original group */ 1141 BUG_ON(cfqq->cfqg != &cfqd->root_group); 1142 if (!RB_EMPTY_NODE(&cfqq->rb_node)) 1143 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1144 cfq_put_cfqg(cfqq->cfqg); 1145 cfqq->cfqg = cfqq->orig_cfqg; 1146 cfqq->orig_cfqg = NULL; 1147 group_changed = 1; 1148 cfq_log_cfqq(cfqd, cfqq, "moved to origin group"); 1149 } 1150#endif 1151 1152 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1153 cfqq_type(cfqq)); 1154 if (cfq_class_idle(cfqq)) { 1155 rb_key = CFQ_IDLE_DELAY; 1156 parent = rb_last(&service_tree->rb); 1157 if (parent && parent != &cfqq->rb_node) { 1158 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1159 rb_key += __cfqq->rb_key; 1160 } else 1161 rb_key += jiffies; 1162 } else if (!add_front) { 1163 /* 1164 * Get our rb key offset. Subtract any residual slice 1165 * value carried from last service. A negative resid 1166 * count indicates slice overrun, and this should position 1167 * the next service time further away in the tree. 1168 */ 1169 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1170 rb_key -= cfqq->slice_resid; 1171 cfqq->slice_resid = 0; 1172 } else { 1173 rb_key = -HZ; 1174 __cfqq = cfq_rb_first(service_tree); 1175 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1176 } 1177 1178 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1179 new_cfqq = 0; 1180 /* 1181 * same position, nothing more to do 1182 */ 1183 if (rb_key == cfqq->rb_key && 1184 cfqq->service_tree == service_tree) 1185 return; 1186 1187 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1188 cfqq->service_tree = NULL; 1189 } 1190 1191 left = 1; 1192 parent = NULL; 1193 cfqq->service_tree = service_tree; 1194 p = &service_tree->rb.rb_node; 1195 while (*p) { 1196 struct rb_node **n; 1197 1198 parent = *p; 1199 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1200 1201 /* 1202 * sort by key, that represents service time. 1203 */ 1204 if (time_before(rb_key, __cfqq->rb_key)) 1205 n = &(*p)->rb_left; 1206 else { 1207 n = &(*p)->rb_right; 1208 left = 0; 1209 } 1210 1211 p = n; 1212 } 1213 1214 if (left) 1215 service_tree->left = &cfqq->rb_node; 1216 1217 cfqq->rb_key = rb_key; 1218 rb_link_node(&cfqq->rb_node, parent, p); 1219 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1220 service_tree->count++; 1221 if ((add_front || !new_cfqq) && !group_changed) 1222 return; 1223 cfq_group_service_tree_add(cfqd, cfqq->cfqg); 1224} 1225 1226static struct cfq_queue * 1227cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1228 sector_t sector, struct rb_node **ret_parent, 1229 struct rb_node ***rb_link) 1230{ 1231 struct rb_node **p, *parent; 1232 struct cfq_queue *cfqq = NULL; 1233 1234 parent = NULL; 1235 p = &root->rb_node; 1236 while (*p) { 1237 struct rb_node **n; 1238 1239 parent = *p; 1240 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1241 1242 /* 1243 * Sort strictly based on sector. Smallest to the left, 1244 * largest to the right. 1245 */ 1246 if (sector > blk_rq_pos(cfqq->next_rq)) 1247 n = &(*p)->rb_right; 1248 else if (sector < blk_rq_pos(cfqq->next_rq)) 1249 n = &(*p)->rb_left; 1250 else 1251 break; 1252 p = n; 1253 cfqq = NULL; 1254 } 1255 1256 *ret_parent = parent; 1257 if (rb_link) 1258 *rb_link = p; 1259 return cfqq; 1260} 1261 1262static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1263{ 1264 struct rb_node **p, *parent; 1265 struct cfq_queue *__cfqq; 1266 1267 if (cfqq->p_root) { 1268 rb_erase(&cfqq->p_node, cfqq->p_root); 1269 cfqq->p_root = NULL; 1270 } 1271 1272 if (cfq_class_idle(cfqq)) 1273 return; 1274 if (!cfqq->next_rq) 1275 return; 1276 1277 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1278 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1279 blk_rq_pos(cfqq->next_rq), &parent, &p); 1280 if (!__cfqq) { 1281 rb_link_node(&cfqq->p_node, parent, p); 1282 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1283 } else 1284 cfqq->p_root = NULL; 1285} 1286 1287/* 1288 * Update cfqq's position in the service tree. 1289 */ 1290static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1291{ 1292 /* 1293 * Resorting requires the cfqq to be on the RR list already. 1294 */ 1295 if (cfq_cfqq_on_rr(cfqq)) { 1296 cfq_service_tree_add(cfqd, cfqq, 0); 1297 cfq_prio_tree_add(cfqd, cfqq); 1298 } 1299} 1300 1301/* 1302 * add to busy list of queues for service, trying to be fair in ordering 1303 * the pending list according to last request service 1304 */ 1305static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1306{ 1307 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1308 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1309 cfq_mark_cfqq_on_rr(cfqq); 1310 cfqd->busy_queues++; 1311 1312 cfq_resort_rr_list(cfqd, cfqq); 1313} 1314 1315/* 1316 * Called when the cfqq no longer has requests pending, remove it from 1317 * the service tree. 1318 */ 1319static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1320{ 1321 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1322 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1323 cfq_clear_cfqq_on_rr(cfqq); 1324 1325 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1326 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1327 cfqq->service_tree = NULL; 1328 } 1329 if (cfqq->p_root) { 1330 rb_erase(&cfqq->p_node, cfqq->p_root); 1331 cfqq->p_root = NULL; 1332 } 1333 1334 cfq_group_service_tree_del(cfqd, cfqq->cfqg); 1335 BUG_ON(!cfqd->busy_queues); 1336 cfqd->busy_queues--; 1337} 1338 1339/* 1340 * rb tree support functions 1341 */ 1342static void cfq_del_rq_rb(struct request *rq) 1343{ 1344 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1345 const int sync = rq_is_sync(rq); 1346 1347 BUG_ON(!cfqq->queued[sync]); 1348 cfqq->queued[sync]--; 1349 1350 elv_rb_del(&cfqq->sort_list, rq); 1351 1352 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1353 /* 1354 * Queue will be deleted from service tree when we actually 1355 * expire it later. Right now just remove it from prio tree 1356 * as it is empty. 1357 */ 1358 if (cfqq->p_root) { 1359 rb_erase(&cfqq->p_node, cfqq->p_root); 1360 cfqq->p_root = NULL; 1361 } 1362 } 1363} 1364 1365static void cfq_add_rq_rb(struct request *rq) 1366{ 1367 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1368 struct cfq_data *cfqd = cfqq->cfqd; 1369 struct request *__alias, *prev; 1370 1371 cfqq->queued[rq_is_sync(rq)]++; 1372 1373 /* 1374 * looks a little odd, but the first insert might return an alias. 1375 * if that happens, put the alias on the dispatch list 1376 */ 1377 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) 1378 cfq_dispatch_insert(cfqd->queue, __alias); 1379 1380 if (!cfq_cfqq_on_rr(cfqq)) 1381 cfq_add_cfqq_rr(cfqd, cfqq); 1382 1383 /* 1384 * check if this request is a better next-serve candidate 1385 */ 1386 prev = cfqq->next_rq; 1387 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1388 1389 /* 1390 * adjust priority tree position, if ->next_rq changes 1391 */ 1392 if (prev != cfqq->next_rq) 1393 cfq_prio_tree_add(cfqd, cfqq); 1394 1395 BUG_ON(!cfqq->next_rq); 1396} 1397 1398static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1399{ 1400 elv_rb_del(&cfqq->sort_list, rq); 1401 cfqq->queued[rq_is_sync(rq)]--; 1402 blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq), 1403 rq_is_sync(rq)); 1404 cfq_add_rq_rb(rq); 1405 blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 1406 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), 1407 rq_is_sync(rq)); 1408} 1409 1410static struct request * 1411cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1412{ 1413 struct task_struct *tsk = current; 1414 struct cfq_io_context *cic; 1415 struct cfq_queue *cfqq; 1416 1417 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1418 if (!cic) 1419 return NULL; 1420 1421 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1422 if (cfqq) { 1423 sector_t sector = bio->bi_sector + bio_sectors(bio); 1424 1425 return elv_rb_find(&cfqq->sort_list, sector); 1426 } 1427 1428 return NULL; 1429} 1430 1431static void cfq_activate_request(struct request_queue *q, struct request *rq) 1432{ 1433 struct cfq_data *cfqd = q->elevator->elevator_data; 1434 1435 cfqd->rq_in_driver++; 1436 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1437 cfqd->rq_in_driver); 1438 1439 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1440} 1441 1442static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1443{ 1444 struct cfq_data *cfqd = q->elevator->elevator_data; 1445 1446 WARN_ON(!cfqd->rq_in_driver); 1447 cfqd->rq_in_driver--; 1448 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1449 cfqd->rq_in_driver); 1450} 1451 1452static void cfq_remove_request(struct request *rq) 1453{ 1454 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1455 1456 if (cfqq->next_rq == rq) 1457 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1458 1459 list_del_init(&rq->queuelist); 1460 cfq_del_rq_rb(rq); 1461 1462 cfqq->cfqd->rq_queued--; 1463 blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq), 1464 rq_is_sync(rq)); 1465 if (rq_is_meta(rq)) { 1466 WARN_ON(!cfqq->meta_pending); 1467 cfqq->meta_pending--; 1468 } 1469} 1470 1471static int cfq_merge(struct request_queue *q, struct request **req, 1472 struct bio *bio) 1473{ 1474 struct cfq_data *cfqd = q->elevator->elevator_data; 1475 struct request *__rq; 1476 1477 __rq = cfq_find_rq_fmerge(cfqd, bio); 1478 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1479 *req = __rq; 1480 return ELEVATOR_FRONT_MERGE; 1481 } 1482 1483 return ELEVATOR_NO_MERGE; 1484} 1485 1486static void cfq_merged_request(struct request_queue *q, struct request *req, 1487 int type) 1488{ 1489 if (type == ELEVATOR_FRONT_MERGE) { 1490 struct cfq_queue *cfqq = RQ_CFQQ(req); 1491 1492 cfq_reposition_rq_rb(cfqq, req); 1493 } 1494} 1495 1496static void cfq_bio_merged(struct request_queue *q, struct request *req, 1497 struct bio *bio) 1498{ 1499 blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, bio_data_dir(bio), 1500 cfq_bio_sync(bio)); 1501} 1502 1503static void 1504cfq_merged_requests(struct request_queue *q, struct request *rq, 1505 struct request *next) 1506{ 1507 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1508 /* 1509 * reposition in fifo if next is older than rq 1510 */ 1511 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1512 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1513 list_move(&rq->queuelist, &next->queuelist); 1514 rq_set_fifo_time(rq, rq_fifo_time(next)); 1515 } 1516 1517 if (cfqq->next_rq == next) 1518 cfqq->next_rq = rq; 1519 cfq_remove_request(next); 1520 blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(next), 1521 rq_is_sync(next)); 1522} 1523 1524static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1525 struct bio *bio) 1526{ 1527 struct cfq_data *cfqd = q->elevator->elevator_data; 1528 struct cfq_io_context *cic; 1529 struct cfq_queue *cfqq; 1530 1531 /* 1532 * Disallow merge of a sync bio into an async request. 1533 */ 1534 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1535 return false; 1536 1537 /* 1538 * Lookup the cfqq that this bio will be queued with. Allow 1539 * merge only if rq is queued there. 1540 */ 1541 cic = cfq_cic_lookup(cfqd, current->io_context); 1542 if (!cic) 1543 return false; 1544 1545 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1546 return cfqq == RQ_CFQQ(rq); 1547} 1548 1549static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1550{ 1551 del_timer(&cfqd->idle_slice_timer); 1552 blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); 1553} 1554 1555static void __cfq_set_active_queue(struct cfq_data *cfqd, 1556 struct cfq_queue *cfqq) 1557{ 1558 if (cfqq) { 1559 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1560 cfqd->serving_prio, cfqd->serving_type); 1561 blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); 1562 cfqq->slice_start = 0; 1563 cfqq->dispatch_start = jiffies; 1564 cfqq->allocated_slice = 0; 1565 cfqq->slice_end = 0; 1566 cfqq->slice_dispatch = 0; 1567 1568 cfq_clear_cfqq_wait_request(cfqq); 1569 cfq_clear_cfqq_must_dispatch(cfqq); 1570 cfq_clear_cfqq_must_alloc_slice(cfqq); 1571 cfq_clear_cfqq_fifo_expire(cfqq); 1572 cfq_mark_cfqq_slice_new(cfqq); 1573 1574 cfq_del_timer(cfqd, cfqq); 1575 } 1576 1577 cfqd->active_queue = cfqq; 1578} 1579 1580/* 1581 * current cfqq expired its slice (or was too idle), select new one 1582 */ 1583static void 1584__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1585 bool timed_out) 1586{ 1587 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1588 1589 if (cfq_cfqq_wait_request(cfqq)) 1590 cfq_del_timer(cfqd, cfqq); 1591 1592 cfq_clear_cfqq_wait_request(cfqq); 1593 cfq_clear_cfqq_wait_busy(cfqq); 1594 1595 /* 1596 * If this cfqq is shared between multiple processes, check to 1597 * make sure that those processes are still issuing I/Os within 1598 * the mean seek distance. If not, it may be time to break the 1599 * queues apart again. 1600 */ 1601 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1602 cfq_mark_cfqq_split_coop(cfqq); 1603 1604 /* 1605 * store what was left of this slice, if the queue idled/timed out 1606 */ 1607 if (timed_out && !cfq_cfqq_slice_new(cfqq)) { 1608 cfqq->slice_resid = cfqq->slice_end - jiffies; 1609 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1610 } 1611 1612 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1613 1614 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1615 cfq_del_cfqq_rr(cfqd, cfqq); 1616 1617 cfq_resort_rr_list(cfqd, cfqq); 1618 1619 if (cfqq == cfqd->active_queue) 1620 cfqd->active_queue = NULL; 1621 1622 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active) 1623 cfqd->grp_service_tree.active = NULL; 1624 1625 if (cfqd->active_cic) { 1626 put_io_context(cfqd->active_cic->ioc); 1627 cfqd->active_cic = NULL; 1628 } 1629} 1630 1631static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1632{ 1633 struct cfq_queue *cfqq = cfqd->active_queue; 1634 1635 if (cfqq) 1636 __cfq_slice_expired(cfqd, cfqq, timed_out); 1637} 1638 1639/* 1640 * Get next queue for service. Unless we have a queue preemption, 1641 * we'll simply select the first cfqq in the service tree. 1642 */ 1643static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1644{ 1645 struct cfq_rb_root *service_tree = 1646 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1647 cfqd->serving_type); 1648 1649 if (!cfqd->rq_queued) 1650 return NULL; 1651 1652 /* There is nothing to dispatch */ 1653 if (!service_tree) 1654 return NULL; 1655 if (RB_EMPTY_ROOT(&service_tree->rb)) 1656 return NULL; 1657 return cfq_rb_first(service_tree); 1658} 1659 1660static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1661{ 1662 struct cfq_group *cfqg; 1663 struct cfq_queue *cfqq; 1664 int i, j; 1665 struct cfq_rb_root *st; 1666 1667 if (!cfqd->rq_queued) 1668 return NULL; 1669 1670 cfqg = cfq_get_next_cfqg(cfqd); 1671 if (!cfqg) 1672 return NULL; 1673 1674 for_each_cfqg_st(cfqg, i, j, st) 1675 if ((cfqq = cfq_rb_first(st)) != NULL) 1676 return cfqq; 1677 return NULL; 1678} 1679 1680/* 1681 * Get and set a new active queue for service. 1682 */ 1683static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1684 struct cfq_queue *cfqq) 1685{ 1686 if (!cfqq) 1687 cfqq = cfq_get_next_queue(cfqd); 1688 1689 __cfq_set_active_queue(cfqd, cfqq); 1690 return cfqq; 1691} 1692 1693static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1694 struct request *rq) 1695{ 1696 if (blk_rq_pos(rq) >= cfqd->last_position) 1697 return blk_rq_pos(rq) - cfqd->last_position; 1698 else 1699 return cfqd->last_position - blk_rq_pos(rq); 1700} 1701 1702static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1703 struct request *rq) 1704{ 1705 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1706} 1707 1708static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1709 struct cfq_queue *cur_cfqq) 1710{ 1711 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1712 struct rb_node *parent, *node; 1713 struct cfq_queue *__cfqq; 1714 sector_t sector = cfqd->last_position; 1715 1716 if (RB_EMPTY_ROOT(root)) 1717 return NULL; 1718 1719 /* 1720 * First, if we find a request starting at the end of the last 1721 * request, choose it. 1722 */ 1723 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1724 if (__cfqq) 1725 return __cfqq; 1726 1727 /* 1728 * If the exact sector wasn't found, the parent of the NULL leaf 1729 * will contain the closest sector. 1730 */ 1731 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1732 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1733 return __cfqq; 1734 1735 if (blk_rq_pos(__cfqq->next_rq) < sector) 1736 node = rb_next(&__cfqq->p_node); 1737 else 1738 node = rb_prev(&__cfqq->p_node); 1739 if (!node) 1740 return NULL; 1741 1742 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1743 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1744 return __cfqq; 1745 1746 return NULL; 1747} 1748 1749/* 1750 * cfqd - obvious 1751 * cur_cfqq - passed in so that we don't decide that the current queue is 1752 * closely cooperating with itself. 1753 * 1754 * So, basically we're assuming that that cur_cfqq has dispatched at least 1755 * one request, and that cfqd->last_position reflects a position on the disk 1756 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1757 * assumption. 1758 */ 1759static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1760 struct cfq_queue *cur_cfqq) 1761{ 1762 struct cfq_queue *cfqq; 1763 1764 if (cfq_class_idle(cur_cfqq)) 1765 return NULL; 1766 if (!cfq_cfqq_sync(cur_cfqq)) 1767 return NULL; 1768 if (CFQQ_SEEKY(cur_cfqq)) 1769 return NULL; 1770 1771 /* 1772 * Don't search priority tree if it's the only queue in the group. 1773 */ 1774 if (cur_cfqq->cfqg->nr_cfqq == 1) 1775 return NULL; 1776 1777 /* 1778 * We should notice if some of the queues are cooperating, eg 1779 * working closely on the same area of the disk. In that case, 1780 * we can group them together and don't waste time idling. 1781 */ 1782 cfqq = cfqq_close(cfqd, cur_cfqq); 1783 if (!cfqq) 1784 return NULL; 1785 1786 /* If new queue belongs to different cfq_group, don't choose it */ 1787 if (cur_cfqq->cfqg != cfqq->cfqg) 1788 return NULL; 1789 1790 /* 1791 * It only makes sense to merge sync queues. 1792 */ 1793 if (!cfq_cfqq_sync(cfqq)) 1794 return NULL; 1795 if (CFQQ_SEEKY(cfqq)) 1796 return NULL; 1797 1798 /* 1799 * Do not merge queues of different priority classes 1800 */ 1801 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1802 return NULL; 1803 1804 return cfqq; 1805} 1806 1807/* 1808 * Determine whether we should enforce idle window for this queue. 1809 */ 1810 1811static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1812{ 1813 enum wl_prio_t prio = cfqq_prio(cfqq); 1814 struct cfq_rb_root *service_tree = cfqq->service_tree; 1815 1816 BUG_ON(!service_tree); 1817 BUG_ON(!service_tree->count); 1818 1819 /* We never do for idle class queues. */ 1820 if (prio == IDLE_WORKLOAD) 1821 return false; 1822 1823 /* We do for queues that were marked with idle window flag. */ 1824 if (cfq_cfqq_idle_window(cfqq) && 1825 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 1826 return true; 1827 1828 /* 1829 * Otherwise, we do only if they are the last ones 1830 * in their service tree. 1831 */ 1832 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) 1833 return 1; 1834 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 1835 service_tree->count); 1836 return 0; 1837} 1838 1839static void cfq_arm_slice_timer(struct cfq_data *cfqd) 1840{ 1841 struct cfq_queue *cfqq = cfqd->active_queue; 1842 struct cfq_io_context *cic; 1843 unsigned long sl; 1844 1845 /* 1846 * SSD device without seek penalty, disable idling. But only do so 1847 * for devices that support queuing, otherwise we still have a problem 1848 * with sync vs async workloads. 1849 */ 1850 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 1851 return; 1852 1853 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 1854 WARN_ON(cfq_cfqq_slice_new(cfqq)); 1855 1856 /* 1857 * idle is disabled, either manually or by past process history 1858 */ 1859 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) 1860 return; 1861 1862 /* 1863 * still active requests from this queue, don't idle 1864 */ 1865 if (cfqq->dispatched) 1866 return; 1867 1868 /* 1869 * task has exited, don't wait 1870 */ 1871 cic = cfqd->active_cic; 1872 if (!cic || !atomic_read(&cic->ioc->nr_tasks)) 1873 return; 1874 1875 /* 1876 * If our average think time is larger than the remaining time 1877 * slice, then don't idle. This avoids overrunning the allotted 1878 * time slice. 1879 */ 1880 if (sample_valid(cic->ttime_samples) && 1881 (cfqq->slice_end - jiffies < cic->ttime_mean)) { 1882 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d", 1883 cic->ttime_mean); 1884 return; 1885 } 1886 1887 cfq_mark_cfqq_wait_request(cfqq); 1888 1889 sl = cfqd->cfq_slice_idle; 1890 1891 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 1892 blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); 1893 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); 1894} 1895 1896/* 1897 * Move request from internal lists to the request queue dispatch list. 1898 */ 1899static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 1900{ 1901 struct cfq_data *cfqd = q->elevator->elevator_data; 1902 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1903 1904 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 1905 1906 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 1907 cfq_remove_request(rq); 1908 cfqq->dispatched++; 1909 elv_dispatch_sort(q, rq); 1910 1911 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 1912 blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), 1913 rq_data_dir(rq), rq_is_sync(rq)); 1914} 1915 1916/* 1917 * return expired entry, or NULL to just start from scratch in rbtree 1918 */ 1919static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 1920{ 1921 struct request *rq = NULL; 1922 1923 if (cfq_cfqq_fifo_expire(cfqq)) 1924 return NULL; 1925 1926 cfq_mark_cfqq_fifo_expire(cfqq); 1927 1928 if (list_empty(&cfqq->fifo)) 1929 return NULL; 1930 1931 rq = rq_entry_fifo(cfqq->fifo.next); 1932 if (time_before(jiffies, rq_fifo_time(rq))) 1933 rq = NULL; 1934 1935 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 1936 return rq; 1937} 1938 1939static inline int 1940cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1941{ 1942 const int base_rq = cfqd->cfq_slice_async_rq; 1943 1944 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 1945 1946 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); 1947} 1948 1949/* 1950 * Must be called with the queue_lock held. 1951 */ 1952static int cfqq_process_refs(struct cfq_queue *cfqq) 1953{ 1954 int process_refs, io_refs; 1955 1956 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 1957 process_refs = atomic_read(&cfqq->ref) - io_refs; 1958 BUG_ON(process_refs < 0); 1959 return process_refs; 1960} 1961 1962static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 1963{ 1964 int process_refs, new_process_refs; 1965 struct cfq_queue *__cfqq; 1966 1967 /* Avoid a circular list and skip interim queue merges */ 1968 while ((__cfqq = new_cfqq->new_cfqq)) { 1969 if (__cfqq == cfqq) 1970 return; 1971 new_cfqq = __cfqq; 1972 } 1973 1974 process_refs = cfqq_process_refs(cfqq); 1975 /* 1976 * If the process for the cfqq has gone away, there is no 1977 * sense in merging the queues. 1978 */ 1979 if (process_refs == 0) 1980 return; 1981 1982 /* 1983 * Merge in the direction of the lesser amount of work. 1984 */ 1985 new_process_refs = cfqq_process_refs(new_cfqq); 1986 if (new_process_refs >= process_refs) { 1987 cfqq->new_cfqq = new_cfqq; 1988 atomic_add(process_refs, &new_cfqq->ref); 1989 } else { 1990 new_cfqq->new_cfqq = cfqq; 1991 atomic_add(new_process_refs, &cfqq->ref); 1992 } 1993} 1994 1995static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 1996 struct cfq_group *cfqg, enum wl_prio_t prio) 1997{ 1998 struct cfq_queue *queue; 1999 int i; 2000 bool key_valid = false; 2001 unsigned long lowest_key = 0; 2002 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2003 2004 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2005 /* select the one with lowest rb_key */ 2006 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2007 if (queue && 2008 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2009 lowest_key = queue->rb_key; 2010 cur_best = i; 2011 key_valid = true; 2012 } 2013 } 2014 2015 return cur_best; 2016} 2017 2018static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2019{ 2020 unsigned slice; 2021 unsigned count; 2022 struct cfq_rb_root *st; 2023 unsigned group_slice; 2024 2025 if (!cfqg) { 2026 cfqd->serving_prio = IDLE_WORKLOAD; 2027 cfqd->workload_expires = jiffies + 1; 2028 return; 2029 } 2030 2031 /* Choose next priority. RT > BE > IDLE */ 2032 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2033 cfqd->serving_prio = RT_WORKLOAD; 2034 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2035 cfqd->serving_prio = BE_WORKLOAD; 2036 else { 2037 cfqd->serving_prio = IDLE_WORKLOAD; 2038 cfqd->workload_expires = jiffies + 1; 2039 return; 2040 } 2041 2042 /* 2043 * For RT and BE, we have to choose also the type 2044 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2045 * expiration time 2046 */ 2047 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2048 count = st->count; 2049 2050 /* 2051 * check workload expiration, and that we still have other queues ready 2052 */ 2053 if (count && !time_after(jiffies, cfqd->workload_expires)) 2054 return; 2055 2056 /* otherwise select new workload type */ 2057 cfqd->serving_type = 2058 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2059 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2060 count = st->count; 2061 2062 /* 2063 * the workload slice is computed as a fraction of target latency 2064 * proportional to the number of queues in that workload, over 2065 * all the queues in the same priority class 2066 */ 2067 group_slice = cfq_group_slice(cfqd, cfqg); 2068 2069 slice = group_slice * count / 2070 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2071 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2072 2073 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2074 unsigned int tmp; 2075 2076 /* 2077 * Async queues are currently system wide. Just taking 2078 * proportion of queues with-in same group will lead to higher 2079 * async ratio system wide as generally root group is going 2080 * to have higher weight. A more accurate thing would be to 2081 * calculate system wide asnc/sync ratio. 2082 */ 2083 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2084 tmp = tmp/cfqd->busy_queues; 2085 slice = min_t(unsigned, slice, tmp); 2086 2087 /* async workload slice is scaled down according to 2088 * the sync/async slice ratio. */ 2089 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2090 } else 2091 /* sync workload slice is at least 2 * cfq_slice_idle */ 2092 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2093 2094 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2095 cfq_log(cfqd, "workload slice:%d", slice); 2096 cfqd->workload_expires = jiffies + slice; 2097 cfqd->noidle_tree_requires_idle = false; 2098} 2099 2100static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2101{ 2102 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2103 struct cfq_group *cfqg; 2104 2105 if (RB_EMPTY_ROOT(&st->rb)) 2106 return NULL; 2107 cfqg = cfq_rb_first_group(st); 2108 st->active = &cfqg->rb_node; 2109 update_min_vdisktime(st); 2110 return cfqg; 2111} 2112 2113static void cfq_choose_cfqg(struct cfq_data *cfqd) 2114{ 2115 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2116 2117 cfqd->serving_group = cfqg; 2118 2119 /* Restore the workload type data */ 2120 if (cfqg->saved_workload_slice) { 2121 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2122 cfqd->serving_type = cfqg->saved_workload; 2123 cfqd->serving_prio = cfqg->saved_serving_prio; 2124 } else 2125 cfqd->workload_expires = jiffies - 1; 2126 2127 choose_service_tree(cfqd, cfqg); 2128} 2129 2130/* 2131 * Select a queue for service. If we have a current active queue, 2132 * check whether to continue servicing it, or retrieve and set a new one. 2133 */ 2134static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2135{ 2136 struct cfq_queue *cfqq, *new_cfqq = NULL; 2137 2138 cfqq = cfqd->active_queue; 2139 if (!cfqq) 2140 goto new_queue; 2141 2142 if (!cfqd->rq_queued) 2143 return NULL; 2144 2145 /* 2146 * We were waiting for group to get backlogged. Expire the queue 2147 */ 2148 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2149 goto expire; 2150 2151 /* 2152 * The active queue has run out of time, expire it and select new. 2153 */ 2154 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2155 /* 2156 * If slice had not expired at the completion of last request 2157 * we might not have turned on wait_busy flag. Don't expire 2158 * the queue yet. Allow the group to get backlogged. 2159 * 2160 * The very fact that we have used the slice, that means we 2161 * have been idling all along on this queue and it should be 2162 * ok to wait for this request to complete. 2163 */ 2164 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2165 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2166 cfqq = NULL; 2167 goto keep_queue; 2168 } else 2169 goto expire; 2170 } 2171 2172 /* 2173 * The active queue has requests and isn't expired, allow it to 2174 * dispatch. 2175 */ 2176 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2177 goto keep_queue; 2178 2179 /* 2180 * If another queue has a request waiting within our mean seek 2181 * distance, let it run. The expire code will check for close 2182 * cooperators and put the close queue at the front of the service 2183 * tree. If possible, merge the expiring queue with the new cfqq. 2184 */ 2185 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2186 if (new_cfqq) { 2187 if (!cfqq->new_cfqq) 2188 cfq_setup_merge(cfqq, new_cfqq); 2189 goto expire; 2190 } 2191 2192 /* 2193 * No requests pending. If the active queue still has requests in 2194 * flight or is idling for a new request, allow either of these 2195 * conditions to happen (or time out) before selecting a new queue. 2196 */ 2197 if (timer_pending(&cfqd->idle_slice_timer) || 2198 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { 2199 cfqq = NULL; 2200 goto keep_queue; 2201 } 2202 2203expire: 2204 cfq_slice_expired(cfqd, 0); 2205new_queue: 2206 /* 2207 * Current queue expired. Check if we have to switch to a new 2208 * service tree 2209 */ 2210 if (!new_cfqq) 2211 cfq_choose_cfqg(cfqd); 2212 2213 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2214keep_queue: 2215 return cfqq; 2216} 2217 2218static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2219{ 2220 int dispatched = 0; 2221 2222 while (cfqq->next_rq) { 2223 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2224 dispatched++; 2225 } 2226 2227 BUG_ON(!list_empty(&cfqq->fifo)); 2228 2229 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2230 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2231 return dispatched; 2232} 2233 2234/* 2235 * Drain our current requests. Used for barriers and when switching 2236 * io schedulers on-the-fly. 2237 */ 2238static int cfq_forced_dispatch(struct cfq_data *cfqd) 2239{ 2240 struct cfq_queue *cfqq; 2241 int dispatched = 0; 2242 2243 /* Expire the timeslice of the current active queue first */ 2244 cfq_slice_expired(cfqd, 0); 2245 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2246 __cfq_set_active_queue(cfqd, cfqq); 2247 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2248 } 2249 2250 BUG_ON(cfqd->busy_queues); 2251 2252 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2253 return dispatched; 2254} 2255 2256static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2257 struct cfq_queue *cfqq) 2258{ 2259 /* the queue hasn't finished any request, can't estimate */ 2260 if (cfq_cfqq_slice_new(cfqq)) 2261 return 1; 2262 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2263 cfqq->slice_end)) 2264 return 1; 2265 2266 return 0; 2267} 2268 2269static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2270{ 2271 unsigned int max_dispatch; 2272 2273 /* 2274 * Drain async requests before we start sync IO 2275 */ 2276 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2277 return false; 2278 2279 /* 2280 * If this is an async queue and we have sync IO in flight, let it wait 2281 */ 2282 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2283 return false; 2284 2285 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2286 if (cfq_class_idle(cfqq)) 2287 max_dispatch = 1; 2288 2289 /* 2290 * Does this cfqq already have too much IO in flight? 2291 */ 2292 if (cfqq->dispatched >= max_dispatch) { 2293 /* 2294 * idle queue must always only have a single IO in flight 2295 */ 2296 if (cfq_class_idle(cfqq)) 2297 return false; 2298 2299 /* 2300 * We have other queues, don't allow more IO from this one 2301 */ 2302 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq)) 2303 return false; 2304 2305 /* 2306 * Sole queue user, no limit 2307 */ 2308 if (cfqd->busy_queues == 1) 2309 max_dispatch = -1; 2310 else 2311 /* 2312 * Normally we start throttling cfqq when cfq_quantum/2 2313 * requests have been dispatched. But we can drive 2314 * deeper queue depths at the beginning of slice 2315 * subjected to upper limit of cfq_quantum. 2316 * */ 2317 max_dispatch = cfqd->cfq_quantum; 2318 } 2319 2320 /* 2321 * Async queues must wait a bit before being allowed dispatch. 2322 * We also ramp up the dispatch depth gradually for async IO, 2323 * based on the last sync IO we serviced 2324 */ 2325 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2326 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2327 unsigned int depth; 2328 2329 depth = last_sync / cfqd->cfq_slice[1]; 2330 if (!depth && !cfqq->dispatched) 2331 depth = 1; 2332 if (depth < max_dispatch) 2333 max_dispatch = depth; 2334 } 2335 2336 /* 2337 * If we're below the current max, allow a dispatch 2338 */ 2339 return cfqq->dispatched < max_dispatch; 2340} 2341 2342/* 2343 * Dispatch a request from cfqq, moving them to the request queue 2344 * dispatch list. 2345 */ 2346static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2347{ 2348 struct request *rq; 2349 2350 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2351 2352 if (!cfq_may_dispatch(cfqd, cfqq)) 2353 return false; 2354 2355 /* 2356 * follow expired path, else get first next available 2357 */ 2358 rq = cfq_check_fifo(cfqq); 2359 if (!rq) 2360 rq = cfqq->next_rq; 2361 2362 /* 2363 * insert request into driver dispatch list 2364 */ 2365 cfq_dispatch_insert(cfqd->queue, rq); 2366 2367 if (!cfqd->active_cic) { 2368 struct cfq_io_context *cic = RQ_CIC(rq); 2369 2370 atomic_long_inc(&cic->ioc->refcount); 2371 cfqd->active_cic = cic; 2372 } 2373 2374 return true; 2375} 2376 2377/* 2378 * Find the cfqq that we need to service and move a request from that to the 2379 * dispatch list 2380 */ 2381static int cfq_dispatch_requests(struct request_queue *q, int force) 2382{ 2383 struct cfq_data *cfqd = q->elevator->elevator_data; 2384 struct cfq_queue *cfqq; 2385 2386 if (!cfqd->busy_queues) 2387 return 0; 2388 2389 if (unlikely(force)) 2390 return cfq_forced_dispatch(cfqd); 2391 2392 cfqq = cfq_select_queue(cfqd); 2393 if (!cfqq) 2394 return 0; 2395 2396 /* 2397 * Dispatch a request from this cfqq, if it is allowed 2398 */ 2399 if (!cfq_dispatch_request(cfqd, cfqq)) 2400 return 0; 2401 2402 cfqq->slice_dispatch++; 2403 cfq_clear_cfqq_must_dispatch(cfqq); 2404 2405 /* 2406 * expire an async queue immediately if it has used up its slice. idle 2407 * queue always expire after 1 dispatch round. 2408 */ 2409 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2410 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2411 cfq_class_idle(cfqq))) { 2412 cfqq->slice_end = jiffies + 1; 2413 cfq_slice_expired(cfqd, 0); 2414 } 2415 2416 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2417 return 1; 2418} 2419 2420/* 2421 * task holds one reference to the queue, dropped when task exits. each rq 2422 * in-flight on this queue also holds a reference, dropped when rq is freed. 2423 * 2424 * Each cfq queue took a reference on the parent group. Drop it now. 2425 * queue lock must be held here. 2426 */ 2427static void cfq_put_queue(struct cfq_queue *cfqq) 2428{ 2429 struct cfq_data *cfqd = cfqq->cfqd; 2430 struct cfq_group *cfqg, *orig_cfqg; 2431 2432 BUG_ON(atomic_read(&cfqq->ref) <= 0); 2433 2434 if (!atomic_dec_and_test(&cfqq->ref)) 2435 return; 2436 2437 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2438 BUG_ON(rb_first(&cfqq->sort_list)); 2439 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2440 cfqg = cfqq->cfqg; 2441 orig_cfqg = cfqq->orig_cfqg; 2442 2443 if (unlikely(cfqd->active_queue == cfqq)) { 2444 __cfq_slice_expired(cfqd, cfqq, 0); 2445 cfq_schedule_dispatch(cfqd); 2446 } 2447 2448 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2449 kmem_cache_free(cfq_pool, cfqq); 2450 cfq_put_cfqg(cfqg); 2451 if (orig_cfqg) 2452 cfq_put_cfqg(orig_cfqg); 2453} 2454 2455/* 2456 * Must always be called with the rcu_read_lock() held 2457 */ 2458static void 2459__call_for_each_cic(struct io_context *ioc, 2460 void (*func)(struct io_context *, struct cfq_io_context *)) 2461{ 2462 struct cfq_io_context *cic; 2463 struct hlist_node *n; 2464 2465 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) 2466 func(ioc, cic); 2467} 2468 2469/* 2470 * Call func for each cic attached to this ioc. 2471 */ 2472static void 2473call_for_each_cic(struct io_context *ioc, 2474 void (*func)(struct io_context *, struct cfq_io_context *)) 2475{ 2476 rcu_read_lock(); 2477 __call_for_each_cic(ioc, func); 2478 rcu_read_unlock(); 2479} 2480 2481static void cfq_cic_free_rcu(struct rcu_head *head) 2482{ 2483 struct cfq_io_context *cic; 2484 2485 cic = container_of(head, struct cfq_io_context, rcu_head); 2486 2487 kmem_cache_free(cfq_ioc_pool, cic); 2488 elv_ioc_count_dec(cfq_ioc_count); 2489 2490 if (ioc_gone) { 2491 /* 2492 * CFQ scheduler is exiting, grab exit lock and check 2493 * the pending io context count. If it hits zero, 2494 * complete ioc_gone and set it back to NULL 2495 */ 2496 spin_lock(&ioc_gone_lock); 2497 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { 2498 complete(ioc_gone); 2499 ioc_gone = NULL; 2500 } 2501 spin_unlock(&ioc_gone_lock); 2502 } 2503} 2504 2505static void cfq_cic_free(struct cfq_io_context *cic) 2506{ 2507 call_rcu(&cic->rcu_head, cfq_cic_free_rcu); 2508} 2509 2510static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) 2511{ 2512 unsigned long flags; 2513 2514 BUG_ON(!cic->dead_key); 2515 2516 spin_lock_irqsave(&ioc->lock, flags); 2517 radix_tree_delete(&ioc->radix_root, cic->dead_key); 2518 hlist_del_rcu(&cic->cic_list); 2519 spin_unlock_irqrestore(&ioc->lock, flags); 2520 2521 cfq_cic_free(cic); 2522} 2523 2524/* 2525 * Must be called with rcu_read_lock() held or preemption otherwise disabled. 2526 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), 2527 * and ->trim() which is called with the task lock held 2528 */ 2529static void cfq_free_io_context(struct io_context *ioc) 2530{ 2531 /* 2532 * ioc->refcount is zero here, or we are called from elv_unregister(), 2533 * so no more cic's are allowed to be linked into this ioc. So it 2534 * should be ok to iterate over the known list, we will see all cic's 2535 * since no new ones are added. 2536 */ 2537 __call_for_each_cic(ioc, cic_free_func); 2538} 2539 2540static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2541{ 2542 struct cfq_queue *__cfqq, *next; 2543 2544 if (unlikely(cfqq == cfqd->active_queue)) { 2545 __cfq_slice_expired(cfqd, cfqq, 0); 2546 cfq_schedule_dispatch(cfqd); 2547 } 2548 2549 /* 2550 * If this queue was scheduled to merge with another queue, be 2551 * sure to drop the reference taken on that queue (and others in 2552 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2553 */ 2554 __cfqq = cfqq->new_cfqq; 2555 while (__cfqq) { 2556 if (__cfqq == cfqq) { 2557 WARN(1, "cfqq->new_cfqq loop detected\n"); 2558 break; 2559 } 2560 next = __cfqq->new_cfqq; 2561 cfq_put_queue(__cfqq); 2562 __cfqq = next; 2563 } 2564 2565 cfq_put_queue(cfqq); 2566} 2567 2568static void __cfq_exit_single_io_context(struct cfq_data *cfqd, 2569 struct cfq_io_context *cic) 2570{ 2571 struct io_context *ioc = cic->ioc; 2572 2573 list_del_init(&cic->queue_list); 2574 2575 /* 2576 * Make sure key == NULL is seen for dead queues 2577 */ 2578 smp_wmb(); 2579 cic->dead_key = (unsigned long) cic->key; 2580 cic->key = NULL; 2581 2582 if (ioc->ioc_data == cic) 2583 rcu_assign_pointer(ioc->ioc_data, NULL); 2584 2585 if (cic->cfqq[BLK_RW_ASYNC]) { 2586 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2587 cic->cfqq[BLK_RW_ASYNC] = NULL; 2588 } 2589 2590 if (cic->cfqq[BLK_RW_SYNC]) { 2591 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2592 cic->cfqq[BLK_RW_SYNC] = NULL; 2593 } 2594} 2595 2596static void cfq_exit_single_io_context(struct io_context *ioc, 2597 struct cfq_io_context *cic) 2598{ 2599 struct cfq_data *cfqd = cic->key; 2600 2601 if (cfqd) { 2602 struct request_queue *q = cfqd->queue; 2603 unsigned long flags; 2604 2605 spin_lock_irqsave(q->queue_lock, flags); 2606 2607 /* 2608 * Ensure we get a fresh copy of the ->key to prevent 2609 * race between exiting task and queue 2610 */ 2611 smp_read_barrier_depends(); 2612 if (cic->key) 2613 __cfq_exit_single_io_context(cfqd, cic); 2614 2615 spin_unlock_irqrestore(q->queue_lock, flags); 2616 } 2617} 2618 2619/* 2620 * The process that ioc belongs to has exited, we need to clean up 2621 * and put the internal structures we have that belongs to that process. 2622 */ 2623static void cfq_exit_io_context(struct io_context *ioc) 2624{ 2625 call_for_each_cic(ioc, cfq_exit_single_io_context); 2626} 2627 2628static struct cfq_io_context * 2629cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2630{ 2631 struct cfq_io_context *cic; 2632 2633 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, 2634 cfqd->queue->node); 2635 if (cic) { 2636 cic->last_end_request = jiffies; 2637 INIT_LIST_HEAD(&cic->queue_list); 2638 INIT_HLIST_NODE(&cic->cic_list); 2639 cic->dtor = cfq_free_io_context; 2640 cic->exit = cfq_exit_io_context; 2641 elv_ioc_count_inc(cfq_ioc_count); 2642 } 2643 2644 return cic; 2645} 2646 2647static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2648{ 2649 struct task_struct *tsk = current; 2650 int ioprio_class; 2651 2652 if (!cfq_cfqq_prio_changed(cfqq)) 2653 return; 2654 2655 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2656 switch (ioprio_class) { 2657 default: 2658 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2659 case IOPRIO_CLASS_NONE: 2660 /* 2661 * no prio set, inherit CPU scheduling settings 2662 */ 2663 cfqq->ioprio = task_nice_ioprio(tsk); 2664 cfqq->ioprio_class = task_nice_ioclass(tsk); 2665 break; 2666 case IOPRIO_CLASS_RT: 2667 cfqq->ioprio = task_ioprio(ioc); 2668 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2669 break; 2670 case IOPRIO_CLASS_BE: 2671 cfqq->ioprio = task_ioprio(ioc); 2672 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2673 break; 2674 case IOPRIO_CLASS_IDLE: 2675 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2676 cfqq->ioprio = 7; 2677 cfq_clear_cfqq_idle_window(cfqq); 2678 break; 2679 } 2680 2681 /* 2682 * keep track of original prio settings in case we have to temporarily 2683 * elevate the priority of this queue 2684 */ 2685 cfqq->org_ioprio = cfqq->ioprio; 2686 cfqq->org_ioprio_class = cfqq->ioprio_class; 2687 cfq_clear_cfqq_prio_changed(cfqq); 2688} 2689 2690static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) 2691{ 2692 struct cfq_data *cfqd = cic->key; 2693 struct cfq_queue *cfqq; 2694 unsigned long flags; 2695 2696 if (unlikely(!cfqd)) 2697 return; 2698 2699 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2700 2701 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2702 if (cfqq) { 2703 struct cfq_queue *new_cfqq; 2704 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, 2705 GFP_ATOMIC); 2706 if (new_cfqq) { 2707 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2708 cfq_put_queue(cfqq); 2709 } 2710 } 2711 2712 cfqq = cic->cfqq[BLK_RW_SYNC]; 2713 if (cfqq) 2714 cfq_mark_cfqq_prio_changed(cfqq); 2715 2716 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2717} 2718 2719static void cfq_ioc_set_ioprio(struct io_context *ioc) 2720{ 2721 call_for_each_cic(ioc, changed_ioprio); 2722 ioc->ioprio_changed = 0; 2723} 2724 2725static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2726 pid_t pid, bool is_sync) 2727{ 2728 RB_CLEAR_NODE(&cfqq->rb_node); 2729 RB_CLEAR_NODE(&cfqq->p_node); 2730 INIT_LIST_HEAD(&cfqq->fifo); 2731 2732 atomic_set(&cfqq->ref, 0); 2733 cfqq->cfqd = cfqd; 2734 2735 cfq_mark_cfqq_prio_changed(cfqq); 2736 2737 if (is_sync) { 2738 if (!cfq_class_idle(cfqq)) 2739 cfq_mark_cfqq_idle_window(cfqq); 2740 cfq_mark_cfqq_sync(cfqq); 2741 } 2742 cfqq->pid = pid; 2743} 2744 2745#ifdef CONFIG_CFQ_GROUP_IOSCHED 2746static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) 2747{ 2748 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2749 struct cfq_data *cfqd = cic->key; 2750 unsigned long flags; 2751 struct request_queue *q; 2752 2753 if (unlikely(!cfqd)) 2754 return; 2755 2756 q = cfqd->queue; 2757 2758 spin_lock_irqsave(q->queue_lock, flags); 2759 2760 if (sync_cfqq) { 2761 /* 2762 * Drop reference to sync queue. A new sync queue will be 2763 * assigned in new group upon arrival of a fresh request. 2764 */ 2765 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2766 cic_set_cfqq(cic, NULL, 1); 2767 cfq_put_queue(sync_cfqq); 2768 } 2769 2770 spin_unlock_irqrestore(q->queue_lock, flags); 2771} 2772 2773static void cfq_ioc_set_cgroup(struct io_context *ioc) 2774{ 2775 call_for_each_cic(ioc, changed_cgroup); 2776 ioc->cgroup_changed = 0; 2777} 2778#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2779 2780static struct cfq_queue * 2781cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2782 struct io_context *ioc, gfp_t gfp_mask) 2783{ 2784 struct cfq_queue *cfqq, *new_cfqq = NULL; 2785 struct cfq_io_context *cic; 2786 struct cfq_group *cfqg; 2787 2788retry: 2789 cfqg = cfq_get_cfqg(cfqd, 1); 2790 cic = cfq_cic_lookup(cfqd, ioc); 2791 /* cic always exists here */ 2792 cfqq = cic_to_cfqq(cic, is_sync); 2793 2794 /* 2795 * Always try a new alloc if we fell back to the OOM cfqq 2796 * originally, since it should just be a temporary situation. 2797 */ 2798 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 2799 cfqq = NULL; 2800 if (new_cfqq) { 2801 cfqq = new_cfqq; 2802 new_cfqq = NULL; 2803 } else if (gfp_mask & __GFP_WAIT) { 2804 spin_unlock_irq(cfqd->queue->queue_lock); 2805 new_cfqq = kmem_cache_alloc_node(cfq_pool, 2806 gfp_mask | __GFP_ZERO, 2807 cfqd->queue->node); 2808 spin_lock_irq(cfqd->queue->queue_lock); 2809 if (new_cfqq) 2810 goto retry; 2811 } else { 2812 cfqq = kmem_cache_alloc_node(cfq_pool, 2813 gfp_mask | __GFP_ZERO, 2814 cfqd->queue->node); 2815 } 2816 2817 if (cfqq) { 2818 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 2819 cfq_init_prio_data(cfqq, ioc); 2820 cfq_link_cfqq_cfqg(cfqq, cfqg); 2821 cfq_log_cfqq(cfqd, cfqq, "alloced"); 2822 } else 2823 cfqq = &cfqd->oom_cfqq; 2824 } 2825 2826 if (new_cfqq) 2827 kmem_cache_free(cfq_pool, new_cfqq); 2828 2829 return cfqq; 2830} 2831 2832static struct cfq_queue ** 2833cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 2834{ 2835 switch (ioprio_class) { 2836 case IOPRIO_CLASS_RT: 2837 return &cfqd->async_cfqq[0][ioprio]; 2838 case IOPRIO_CLASS_BE: 2839 return &cfqd->async_cfqq[1][ioprio]; 2840 case IOPRIO_CLASS_IDLE: 2841 return &cfqd->async_idle_cfqq; 2842 default: 2843 BUG(); 2844 } 2845} 2846 2847static struct cfq_queue * 2848cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 2849 gfp_t gfp_mask) 2850{ 2851 const int ioprio = task_ioprio(ioc); 2852 const int ioprio_class = task_ioprio_class(ioc); 2853 struct cfq_queue **async_cfqq = NULL; 2854 struct cfq_queue *cfqq = NULL; 2855 2856 if (!is_sync) { 2857 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 2858 cfqq = *async_cfqq; 2859 } 2860 2861 if (!cfqq) 2862 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 2863 2864 /* 2865 * pin the queue now that it's allocated, scheduler exit will prune it 2866 */ 2867 if (!is_sync && !(*async_cfqq)) { 2868 atomic_inc(&cfqq->ref); 2869 *async_cfqq = cfqq; 2870 } 2871 2872 atomic_inc(&cfqq->ref); 2873 return cfqq; 2874} 2875 2876/* 2877 * We drop cfq io contexts lazily, so we may find a dead one. 2878 */ 2879static void 2880cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, 2881 struct cfq_io_context *cic) 2882{ 2883 unsigned long flags; 2884 2885 WARN_ON(!list_empty(&cic->queue_list)); 2886 2887 spin_lock_irqsave(&ioc->lock, flags); 2888 2889 BUG_ON(ioc->ioc_data == cic); 2890 2891 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); 2892 hlist_del_rcu(&cic->cic_list); 2893 spin_unlock_irqrestore(&ioc->lock, flags); 2894 2895 cfq_cic_free(cic); 2896} 2897 2898static struct cfq_io_context * 2899cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) 2900{ 2901 struct cfq_io_context *cic; 2902 unsigned long flags; 2903 void *k; 2904 2905 if (unlikely(!ioc)) 2906 return NULL; 2907 2908 rcu_read_lock(); 2909 2910 /* 2911 * we maintain a last-hit cache, to avoid browsing over the tree 2912 */ 2913 cic = rcu_dereference(ioc->ioc_data); 2914 if (cic && cic->key == cfqd) { 2915 rcu_read_unlock(); 2916 return cic; 2917 } 2918 2919 do { 2920 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); 2921 rcu_read_unlock(); 2922 if (!cic) 2923 break; 2924 /* ->key must be copied to avoid race with cfq_exit_queue() */ 2925 k = cic->key; 2926 if (unlikely(!k)) { 2927 cfq_drop_dead_cic(cfqd, ioc, cic); 2928 rcu_read_lock(); 2929 continue; 2930 } 2931 2932 spin_lock_irqsave(&ioc->lock, flags); 2933 rcu_assign_pointer(ioc->ioc_data, cic); 2934 spin_unlock_irqrestore(&ioc->lock, flags); 2935 break; 2936 } while (1); 2937 2938 return cic; 2939} 2940 2941/* 2942 * Add cic into ioc, using cfqd as the search key. This enables us to lookup 2943 * the process specific cfq io context when entered from the block layer. 2944 * Also adds the cic to a per-cfqd list, used when this queue is removed. 2945 */ 2946static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, 2947 struct cfq_io_context *cic, gfp_t gfp_mask) 2948{ 2949 unsigned long flags; 2950 int ret; 2951 2952 ret = radix_tree_preload(gfp_mask); 2953 if (!ret) { 2954 cic->ioc = ioc; 2955 cic->key = cfqd; 2956 2957 spin_lock_irqsave(&ioc->lock, flags); 2958 ret = radix_tree_insert(&ioc->radix_root, 2959 (unsigned long) cfqd, cic); 2960 if (!ret) 2961 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); 2962 spin_unlock_irqrestore(&ioc->lock, flags); 2963 2964 radix_tree_preload_end(); 2965 2966 if (!ret) { 2967 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2968 list_add(&cic->queue_list, &cfqd->cic_list); 2969 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2970 } 2971 } 2972 2973 if (ret) 2974 printk(KERN_ERR "cfq: cic link failed!\n"); 2975 2976 return ret; 2977} 2978 2979/* 2980 * Setup general io context and cfq io context. There can be several cfq 2981 * io contexts per general io context, if this process is doing io to more 2982 * than one device managed by cfq. 2983 */ 2984static struct cfq_io_context * 2985cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2986{ 2987 struct io_context *ioc = NULL; 2988 struct cfq_io_context *cic; 2989 2990 might_sleep_if(gfp_mask & __GFP_WAIT); 2991 2992 ioc = get_io_context(gfp_mask, cfqd->queue->node); 2993 if (!ioc) 2994 return NULL; 2995 2996 cic = cfq_cic_lookup(cfqd, ioc); 2997 if (cic) 2998 goto out; 2999 3000 cic = cfq_alloc_io_context(cfqd, gfp_mask); 3001 if (cic == NULL) 3002 goto err; 3003 3004 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) 3005 goto err_free; 3006 3007out: 3008 smp_read_barrier_depends(); 3009 if (unlikely(ioc->ioprio_changed)) 3010 cfq_ioc_set_ioprio(ioc); 3011 3012#ifdef CONFIG_CFQ_GROUP_IOSCHED 3013 if (unlikely(ioc->cgroup_changed)) 3014 cfq_ioc_set_cgroup(ioc); 3015#endif 3016 return cic; 3017err_free: 3018 cfq_cic_free(cic); 3019err: 3020 put_io_context(ioc); 3021 return NULL; 3022} 3023 3024static void 3025cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) 3026{ 3027 unsigned long elapsed = jiffies - cic->last_end_request; 3028 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); 3029 3030 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; 3031 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; 3032 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; 3033} 3034 3035static void 3036cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3037 struct request *rq) 3038{ 3039 sector_t sdist = 0; 3040 sector_t n_sec = blk_rq_sectors(rq); 3041 if (cfqq->last_request_pos) { 3042 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3043 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3044 else 3045 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3046 } 3047 3048 cfqq->seek_history <<= 1; 3049 if (blk_queue_nonrot(cfqd->queue)) 3050 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3051 else 3052 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3053} 3054 3055/* 3056 * Disable idle window if the process thinks too long or seeks so much that 3057 * it doesn't matter 3058 */ 3059static void 3060cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3061 struct cfq_io_context *cic) 3062{ 3063 int old_idle, enable_idle; 3064 3065 /* 3066 * Don't idle for async or idle io prio class 3067 */ 3068 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3069 return; 3070 3071 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3072 3073 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3074 cfq_mark_cfqq_deep(cfqq); 3075 3076 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || 3077 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3078 enable_idle = 0; 3079 else if (sample_valid(cic->ttime_samples)) { 3080 if (cic->ttime_mean > cfqd->cfq_slice_idle) 3081 enable_idle = 0; 3082 else 3083 enable_idle = 1; 3084 } 3085 3086 if (old_idle != enable_idle) { 3087 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3088 if (enable_idle) 3089 cfq_mark_cfqq_idle_window(cfqq); 3090 else 3091 cfq_clear_cfqq_idle_window(cfqq); 3092 } 3093} 3094 3095/* 3096 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3097 * no or if we aren't sure, a 1 will cause a preempt. 3098 */ 3099static bool 3100cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3101 struct request *rq) 3102{ 3103 struct cfq_queue *cfqq; 3104 3105 cfqq = cfqd->active_queue; 3106 if (!cfqq) 3107 return false; 3108 3109 if (cfq_class_idle(new_cfqq)) 3110 return false; 3111 3112 if (cfq_class_idle(cfqq)) 3113 return true; 3114 3115 /* 3116 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3117 */ 3118 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3119 return false; 3120 3121 /* 3122 * if the new request is sync, but the currently running queue is 3123 * not, let the sync request have priority. 3124 */ 3125 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3126 return true; 3127 3128 if (new_cfqq->cfqg != cfqq->cfqg) 3129 return false; 3130 3131 if (cfq_slice_used(cfqq)) 3132 return true; 3133 3134 /* Allow preemption only if we are idling on sync-noidle tree */ 3135 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3136 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3137 new_cfqq->service_tree->count == 2 && 3138 RB_EMPTY_ROOT(&cfqq->sort_list)) 3139 return true; 3140 3141 /* 3142 * So both queues are sync. Let the new request get disk time if 3143 * it's a metadata request and the current queue is doing regular IO. 3144 */ 3145 if (rq_is_meta(rq) && !cfqq->meta_pending) 3146 return true; 3147 3148 /* 3149 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3150 */ 3151 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3152 return true; 3153 3154 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3155 return false; 3156 3157 /* 3158 * if this request is as-good as one we would expect from the 3159 * current cfqq, let it preempt 3160 */ 3161 if (cfq_rq_close(cfqd, cfqq, rq)) 3162 return true; 3163 3164 return false; 3165} 3166 3167/* 3168 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3169 * let it have half of its nominal slice. 3170 */ 3171static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3172{ 3173 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3174 cfq_slice_expired(cfqd, 1); 3175 3176 /* 3177 * Put the new queue at the front of the of the current list, 3178 * so we know that it will be selected next. 3179 */ 3180 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3181 3182 cfq_service_tree_add(cfqd, cfqq, 1); 3183 3184 cfqq->slice_end = 0; 3185 cfq_mark_cfqq_slice_new(cfqq); 3186} 3187 3188/* 3189 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3190 * something we should do about it 3191 */ 3192static void 3193cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3194 struct request *rq) 3195{ 3196 struct cfq_io_context *cic = RQ_CIC(rq); 3197 3198 cfqd->rq_queued++; 3199 if (rq_is_meta(rq)) 3200 cfqq->meta_pending++; 3201 3202 cfq_update_io_thinktime(cfqd, cic); 3203 cfq_update_io_seektime(cfqd, cfqq, rq); 3204 cfq_update_idle_window(cfqd, cfqq, cic); 3205 3206 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3207 3208 if (cfqq == cfqd->active_queue) { 3209 /* 3210 * Remember that we saw a request from this process, but 3211 * don't start queuing just yet. Otherwise we risk seeing lots 3212 * of tiny requests, because we disrupt the normal plugging 3213 * and merging. If the request is already larger than a single 3214 * page, let it rip immediately. For that case we assume that 3215 * merging is already done. Ditto for a busy system that 3216 * has other work pending, don't risk delaying until the 3217 * idle timer unplug to continue working. 3218 */ 3219 if (cfq_cfqq_wait_request(cfqq)) { 3220 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3221 cfqd->busy_queues > 1) { 3222 cfq_del_timer(cfqd, cfqq); 3223 cfq_clear_cfqq_wait_request(cfqq); 3224 __blk_run_queue(cfqd->queue); 3225 } else { 3226 blkiocg_update_idle_time_stats( 3227 &cfqq->cfqg->blkg); 3228 cfq_mark_cfqq_must_dispatch(cfqq); 3229 } 3230 } 3231 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3232 /* 3233 * not the active queue - expire current slice if it is 3234 * idle and has expired it's mean thinktime or this new queue 3235 * has some old slice time left and is of higher priority or 3236 * this new queue is RT and the current one is BE 3237 */ 3238 cfq_preempt_queue(cfqd, cfqq); 3239 __blk_run_queue(cfqd->queue); 3240 } 3241} 3242 3243static void cfq_insert_request(struct request_queue *q, struct request *rq) 3244{ 3245 struct cfq_data *cfqd = q->elevator->elevator_data; 3246 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3247 3248 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3249 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); 3250 3251 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3252 list_add_tail(&rq->queuelist, &cfqq->fifo); 3253 cfq_add_rq_rb(rq); 3254 blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 3255 &cfqd->serving_group->blkg, rq_data_dir(rq), 3256 rq_is_sync(rq)); 3257 cfq_rq_enqueued(cfqd, cfqq, rq); 3258} 3259 3260/* 3261 * Update hw_tag based on peak queue depth over 50 samples under 3262 * sufficient load. 3263 */ 3264static void cfq_update_hw_tag(struct cfq_data *cfqd) 3265{ 3266 struct cfq_queue *cfqq = cfqd->active_queue; 3267 3268 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3269 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3270 3271 if (cfqd->hw_tag == 1) 3272 return; 3273 3274 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3275 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3276 return; 3277 3278 /* 3279 * If active queue hasn't enough requests and can idle, cfq might not 3280 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3281 * case 3282 */ 3283 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3284 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3285 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3286 return; 3287 3288 if (cfqd->hw_tag_samples++ < 50) 3289 return; 3290 3291 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3292 cfqd->hw_tag = 1; 3293 else 3294 cfqd->hw_tag = 0; 3295} 3296 3297static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3298{ 3299 struct cfq_io_context *cic = cfqd->active_cic; 3300 3301 /* If there are other queues in the group, don't wait */ 3302 if (cfqq->cfqg->nr_cfqq > 1) 3303 return false; 3304 3305 if (cfq_slice_used(cfqq)) 3306 return true; 3307 3308 /* if slice left is less than think time, wait busy */ 3309 if (cic && sample_valid(cic->ttime_samples) 3310 && (cfqq->slice_end - jiffies < cic->ttime_mean)) 3311 return true; 3312 3313 /* 3314 * If think times is less than a jiffy than ttime_mean=0 and above 3315 * will not be true. It might happen that slice has not expired yet 3316 * but will expire soon (4-5 ns) during select_queue(). To cover the 3317 * case where think time is less than a jiffy, mark the queue wait 3318 * busy if only 1 jiffy is left in the slice. 3319 */ 3320 if (cfqq->slice_end - jiffies == 1) 3321 return true; 3322 3323 return false; 3324} 3325 3326static void cfq_completed_request(struct request_queue *q, struct request *rq) 3327{ 3328 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3329 struct cfq_data *cfqd = cfqq->cfqd; 3330 const int sync = rq_is_sync(rq); 3331 unsigned long now; 3332 3333 now = jiffies; 3334 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq)); 3335 3336 cfq_update_hw_tag(cfqd); 3337 3338 WARN_ON(!cfqd->rq_in_driver); 3339 WARN_ON(!cfqq->dispatched); 3340 cfqd->rq_in_driver--; 3341 cfqq->dispatched--; 3342 blkiocg_update_completion_stats(&cfqq->cfqg->blkg, rq_start_time_ns(rq), 3343 rq_io_start_time_ns(rq), rq_data_dir(rq), 3344 rq_is_sync(rq)); 3345 3346 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3347 3348 if (sync) { 3349 RQ_CIC(rq)->last_end_request = now; 3350 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3351 cfqd->last_delayed_sync = now; 3352 } 3353 3354 /* 3355 * If this is the active queue, check if it needs to be expired, 3356 * or if we want to idle in case it has no pending requests. 3357 */ 3358 if (cfqd->active_queue == cfqq) { 3359 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3360 3361 if (cfq_cfqq_slice_new(cfqq)) { 3362 cfq_set_prio_slice(cfqd, cfqq); 3363 cfq_clear_cfqq_slice_new(cfqq); 3364 } 3365 3366 /* 3367 * Should we wait for next request to come in before we expire 3368 * the queue. 3369 */ 3370 if (cfq_should_wait_busy(cfqd, cfqq)) { 3371 cfqq->slice_end = jiffies + cfqd->cfq_slice_idle; 3372 cfq_mark_cfqq_wait_busy(cfqq); 3373 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3374 } 3375 3376 /* 3377 * Idling is not enabled on: 3378 * - expired queues 3379 * - idle-priority queues 3380 * - async queues 3381 * - queues with still some requests queued 3382 * - when there is a close cooperator 3383 */ 3384 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3385 cfq_slice_expired(cfqd, 1); 3386 else if (sync && cfqq_empty && 3387 !cfq_close_cooperator(cfqd, cfqq)) { 3388 cfqd->noidle_tree_requires_idle |= !rq_noidle(rq); 3389 /* 3390 * Idling is enabled for SYNC_WORKLOAD. 3391 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree 3392 * only if we processed at least one !rq_noidle request 3393 */ 3394 if (cfqd->serving_type == SYNC_WORKLOAD 3395 || cfqd->noidle_tree_requires_idle 3396 || cfqq->cfqg->nr_cfqq == 1) 3397 cfq_arm_slice_timer(cfqd); 3398 } 3399 } 3400 3401 if (!cfqd->rq_in_driver) 3402 cfq_schedule_dispatch(cfqd); 3403} 3404 3405/* 3406 * we temporarily boost lower priority queues if they are holding fs exclusive 3407 * resources. they are boosted to normal prio (CLASS_BE/4) 3408 */ 3409static void cfq_prio_boost(struct cfq_queue *cfqq) 3410{ 3411 if (has_fs_excl()) { 3412 /* 3413 * boost idle prio on transactions that would lock out other 3414 * users of the filesystem 3415 */ 3416 if (cfq_class_idle(cfqq)) 3417 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3418 if (cfqq->ioprio > IOPRIO_NORM) 3419 cfqq->ioprio = IOPRIO_NORM; 3420 } else { 3421 /* 3422 * unboost the queue (if needed) 3423 */ 3424 cfqq->ioprio_class = cfqq->org_ioprio_class; 3425 cfqq->ioprio = cfqq->org_ioprio; 3426 } 3427} 3428 3429static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3430{ 3431 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3432 cfq_mark_cfqq_must_alloc_slice(cfqq); 3433 return ELV_MQUEUE_MUST; 3434 } 3435 3436 return ELV_MQUEUE_MAY; 3437} 3438 3439static int cfq_may_queue(struct request_queue *q, int rw) 3440{ 3441 struct cfq_data *cfqd = q->elevator->elevator_data; 3442 struct task_struct *tsk = current; 3443 struct cfq_io_context *cic; 3444 struct cfq_queue *cfqq; 3445 3446 /* 3447 * don't force setup of a queue from here, as a call to may_queue 3448 * does not necessarily imply that a request actually will be queued. 3449 * so just lookup a possibly existing queue, or return 'may queue' 3450 * if that fails 3451 */ 3452 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3453 if (!cic) 3454 return ELV_MQUEUE_MAY; 3455 3456 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3457 if (cfqq) { 3458 cfq_init_prio_data(cfqq, cic->ioc); 3459 cfq_prio_boost(cfqq); 3460 3461 return __cfq_may_queue(cfqq); 3462 } 3463 3464 return ELV_MQUEUE_MAY; 3465} 3466 3467/* 3468 * queue lock held here 3469 */ 3470static void cfq_put_request(struct request *rq) 3471{ 3472 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3473 3474 if (cfqq) { 3475 const int rw = rq_data_dir(rq); 3476 3477 BUG_ON(!cfqq->allocated[rw]); 3478 cfqq->allocated[rw]--; 3479 3480 put_io_context(RQ_CIC(rq)->ioc); 3481 3482 rq->elevator_private = NULL; 3483 rq->elevator_private2 = NULL; 3484 3485 /* Put down rq reference on cfqg */ 3486 cfq_put_cfqg(RQ_CFQG(rq)); 3487 rq->elevator_private3 = NULL; 3488 3489 cfq_put_queue(cfqq); 3490 } 3491} 3492 3493static struct cfq_queue * 3494cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, 3495 struct cfq_queue *cfqq) 3496{ 3497 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3498 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3499 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3500 cfq_put_queue(cfqq); 3501 return cic_to_cfqq(cic, 1); 3502} 3503 3504/* 3505 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3506 * was the last process referring to said cfqq. 3507 */ 3508static struct cfq_queue * 3509split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) 3510{ 3511 if (cfqq_process_refs(cfqq) == 1) { 3512 cfqq->pid = current->pid; 3513 cfq_clear_cfqq_coop(cfqq); 3514 cfq_clear_cfqq_split_coop(cfqq); 3515 return cfqq; 3516 } 3517 3518 cic_set_cfqq(cic, NULL, 1); 3519 cfq_put_queue(cfqq); 3520 return NULL; 3521} 3522/* 3523 * Allocate cfq data structures associated with this request. 3524 */ 3525static int 3526cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3527{ 3528 struct cfq_data *cfqd = q->elevator->elevator_data; 3529 struct cfq_io_context *cic; 3530 const int rw = rq_data_dir(rq); 3531 const bool is_sync = rq_is_sync(rq); 3532 struct cfq_queue *cfqq; 3533 unsigned long flags; 3534 3535 might_sleep_if(gfp_mask & __GFP_WAIT); 3536 3537 cic = cfq_get_io_context(cfqd, gfp_mask); 3538 3539 spin_lock_irqsave(q->queue_lock, flags); 3540 3541 if (!cic) 3542 goto queue_fail; 3543 3544new_queue: 3545 cfqq = cic_to_cfqq(cic, is_sync); 3546 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3547 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); 3548 cic_set_cfqq(cic, cfqq, is_sync); 3549 } else { 3550 /* 3551 * If the queue was seeky for too long, break it apart. 3552 */ 3553 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3554 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3555 cfqq = split_cfqq(cic, cfqq); 3556 if (!cfqq) 3557 goto new_queue; 3558 } 3559 3560 /* 3561 * Check to see if this queue is scheduled to merge with 3562 * another, closely cooperating queue. The merging of 3563 * queues happens here as it must be done in process context. 3564 * The reference on new_cfqq was taken in merge_cfqqs. 3565 */ 3566 if (cfqq->new_cfqq) 3567 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3568 } 3569 3570 cfqq->allocated[rw]++; 3571 atomic_inc(&cfqq->ref); 3572 3573 spin_unlock_irqrestore(q->queue_lock, flags); 3574 3575 rq->elevator_private = cic; 3576 rq->elevator_private2 = cfqq; 3577 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg); 3578 return 0; 3579 3580queue_fail: 3581 if (cic) 3582 put_io_context(cic->ioc); 3583 3584 cfq_schedule_dispatch(cfqd); 3585 spin_unlock_irqrestore(q->queue_lock, flags); 3586 cfq_log(cfqd, "set_request fail"); 3587 return 1; 3588} 3589 3590static void cfq_kick_queue(struct work_struct *work) 3591{ 3592 struct cfq_data *cfqd = 3593 container_of(work, struct cfq_data, unplug_work); 3594 struct request_queue *q = cfqd->queue; 3595 3596 spin_lock_irq(q->queue_lock); 3597 __blk_run_queue(cfqd->queue); 3598 spin_unlock_irq(q->queue_lock); 3599} 3600 3601/* 3602 * Timer running if the active_queue is currently idling inside its time slice 3603 */ 3604static void cfq_idle_slice_timer(unsigned long data) 3605{ 3606 struct cfq_data *cfqd = (struct cfq_data *) data; 3607 struct cfq_queue *cfqq; 3608 unsigned long flags; 3609 int timed_out = 1; 3610 3611 cfq_log(cfqd, "idle timer fired"); 3612 3613 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3614 3615 cfqq = cfqd->active_queue; 3616 if (cfqq) { 3617 timed_out = 0; 3618 3619 /* 3620 * We saw a request before the queue expired, let it through 3621 */ 3622 if (cfq_cfqq_must_dispatch(cfqq)) 3623 goto out_kick; 3624 3625 /* 3626 * expired 3627 */ 3628 if (cfq_slice_used(cfqq)) 3629 goto expire; 3630 3631 /* 3632 * only expire and reinvoke request handler, if there are 3633 * other queues with pending requests 3634 */ 3635 if (!cfqd->busy_queues) 3636 goto out_cont; 3637 3638 /* 3639 * not expired and it has a request pending, let it dispatch 3640 */ 3641 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3642 goto out_kick; 3643 3644 /* 3645 * Queue depth flag is reset only when the idle didn't succeed 3646 */ 3647 cfq_clear_cfqq_deep(cfqq); 3648 } 3649expire: 3650 cfq_slice_expired(cfqd, timed_out); 3651out_kick: 3652 cfq_schedule_dispatch(cfqd); 3653out_cont: 3654 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3655} 3656 3657static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3658{ 3659 del_timer_sync(&cfqd->idle_slice_timer); 3660 cancel_work_sync(&cfqd->unplug_work); 3661} 3662 3663static void cfq_put_async_queues(struct cfq_data *cfqd) 3664{ 3665 int i; 3666 3667 for (i = 0; i < IOPRIO_BE_NR; i++) { 3668 if (cfqd->async_cfqq[0][i]) 3669 cfq_put_queue(cfqd->async_cfqq[0][i]); 3670 if (cfqd->async_cfqq[1][i]) 3671 cfq_put_queue(cfqd->async_cfqq[1][i]); 3672 } 3673 3674 if (cfqd->async_idle_cfqq) 3675 cfq_put_queue(cfqd->async_idle_cfqq); 3676} 3677 3678static void cfq_cfqd_free(struct rcu_head *head) 3679{ 3680 kfree(container_of(head, struct cfq_data, rcu)); 3681} 3682 3683static void cfq_exit_queue(struct elevator_queue *e) 3684{ 3685 struct cfq_data *cfqd = e->elevator_data; 3686 struct request_queue *q = cfqd->queue; 3687 3688 cfq_shutdown_timer_wq(cfqd); 3689 3690 spin_lock_irq(q->queue_lock); 3691 3692 if (cfqd->active_queue) 3693 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3694 3695 while (!list_empty(&cfqd->cic_list)) { 3696 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, 3697 struct cfq_io_context, 3698 queue_list); 3699 3700 __cfq_exit_single_io_context(cfqd, cic); 3701 } 3702 3703 cfq_put_async_queues(cfqd); 3704 cfq_release_cfq_groups(cfqd); 3705 blkiocg_del_blkio_group(&cfqd->root_group.blkg); 3706 3707 spin_unlock_irq(q->queue_lock); 3708 3709 cfq_shutdown_timer_wq(cfqd); 3710 3711 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */ 3712 call_rcu(&cfqd->rcu, cfq_cfqd_free); 3713} 3714 3715static void *cfq_init_queue(struct request_queue *q) 3716{ 3717 struct cfq_data *cfqd; 3718 int i, j; 3719 struct cfq_group *cfqg; 3720 struct cfq_rb_root *st; 3721 3722 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3723 if (!cfqd) 3724 return NULL; 3725 3726 /* Init root service tree */ 3727 cfqd->grp_service_tree = CFQ_RB_ROOT; 3728 3729 /* Init root group */ 3730 cfqg = &cfqd->root_group; 3731 for_each_cfqg_st(cfqg, i, j, st) 3732 *st = CFQ_RB_ROOT; 3733 RB_CLEAR_NODE(&cfqg->rb_node); 3734 3735 /* Give preference to root group over other groups */ 3736 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 3737 3738#ifdef CONFIG_CFQ_GROUP_IOSCHED 3739 /* 3740 * Take a reference to root group which we never drop. This is just 3741 * to make sure that cfq_put_cfqg() does not try to kfree root group 3742 */ 3743 atomic_set(&cfqg->ref, 1); 3744 blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd, 3745 0); 3746#endif 3747 /* 3748 * Not strictly needed (since RB_ROOT just clears the node and we 3749 * zeroed cfqd on alloc), but better be safe in case someone decides 3750 * to add magic to the rb code 3751 */ 3752 for (i = 0; i < CFQ_PRIO_LISTS; i++) 3753 cfqd->prio_trees[i] = RB_ROOT; 3754 3755 /* 3756 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 3757 * Grab a permanent reference to it, so that the normal code flow 3758 * will not attempt to free it. 3759 */ 3760 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 3761 atomic_inc(&cfqd->oom_cfqq.ref); 3762 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 3763 3764 INIT_LIST_HEAD(&cfqd->cic_list); 3765 3766 cfqd->queue = q; 3767 3768 init_timer(&cfqd->idle_slice_timer); 3769 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 3770 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 3771 3772 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 3773 3774 cfqd->cfq_quantum = cfq_quantum; 3775 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 3776 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 3777 cfqd->cfq_back_max = cfq_back_max; 3778 cfqd->cfq_back_penalty = cfq_back_penalty; 3779 cfqd->cfq_slice[0] = cfq_slice_async; 3780 cfqd->cfq_slice[1] = cfq_slice_sync; 3781 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 3782 cfqd->cfq_slice_idle = cfq_slice_idle; 3783 cfqd->cfq_latency = 1; 3784 cfqd->cfq_group_isolation = 0; 3785 cfqd->hw_tag = -1; 3786 /* 3787 * we optimistically start assuming sync ops weren't delayed in last 3788 * second, in order to have larger depth for async operations. 3789 */ 3790 cfqd->last_delayed_sync = jiffies - HZ; 3791 INIT_RCU_HEAD(&cfqd->rcu); 3792 return cfqd; 3793} 3794 3795static void cfq_slab_kill(void) 3796{ 3797 /* 3798 * Caller already ensured that pending RCU callbacks are completed, 3799 * so we should have no busy allocations at this point. 3800 */ 3801 if (cfq_pool) 3802 kmem_cache_destroy(cfq_pool); 3803 if (cfq_ioc_pool) 3804 kmem_cache_destroy(cfq_ioc_pool); 3805} 3806 3807static int __init cfq_slab_setup(void) 3808{ 3809 cfq_pool = KMEM_CACHE(cfq_queue, 0); 3810 if (!cfq_pool) 3811 goto fail; 3812 3813 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); 3814 if (!cfq_ioc_pool) 3815 goto fail; 3816 3817 return 0; 3818fail: 3819 cfq_slab_kill(); 3820 return -ENOMEM; 3821} 3822 3823/* 3824 * sysfs parts below --> 3825 */ 3826static ssize_t 3827cfq_var_show(unsigned int var, char *page) 3828{ 3829 return sprintf(page, "%d\n", var); 3830} 3831 3832static ssize_t 3833cfq_var_store(unsigned int *var, const char *page, size_t count) 3834{ 3835 char *p = (char *) page; 3836 3837 *var = simple_strtoul(p, &p, 10); 3838 return count; 3839} 3840 3841#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 3842static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 3843{ \ 3844 struct cfq_data *cfqd = e->elevator_data; \ 3845 unsigned int __data = __VAR; \ 3846 if (__CONV) \ 3847 __data = jiffies_to_msecs(__data); \ 3848 return cfq_var_show(__data, (page)); \ 3849} 3850SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 3851SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 3852SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 3853SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 3854SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 3855SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 3856SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 3857SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 3858SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 3859SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 3860SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0); 3861#undef SHOW_FUNCTION 3862 3863#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 3864static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 3865{ \ 3866 struct cfq_data *cfqd = e->elevator_data; \ 3867 unsigned int __data; \ 3868 int ret = cfq_var_store(&__data, (page), count); \ 3869 if (__data < (MIN)) \ 3870 __data = (MIN); \ 3871 else if (__data > (MAX)) \ 3872 __data = (MAX); \ 3873 if (__CONV) \ 3874 *(__PTR) = msecs_to_jiffies(__data); \ 3875 else \ 3876 *(__PTR) = __data; \ 3877 return ret; \ 3878} 3879STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 3880STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 3881 UINT_MAX, 1); 3882STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 3883 UINT_MAX, 1); 3884STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 3885STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 3886 UINT_MAX, 0); 3887STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 3888STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 3889STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 3890STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 3891 UINT_MAX, 0); 3892STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 3893STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0); 3894#undef STORE_FUNCTION 3895 3896#define CFQ_ATTR(name) \ 3897 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 3898 3899static struct elv_fs_entry cfq_attrs[] = { 3900 CFQ_ATTR(quantum), 3901 CFQ_ATTR(fifo_expire_sync), 3902 CFQ_ATTR(fifo_expire_async), 3903 CFQ_ATTR(back_seek_max), 3904 CFQ_ATTR(back_seek_penalty), 3905 CFQ_ATTR(slice_sync), 3906 CFQ_ATTR(slice_async), 3907 CFQ_ATTR(slice_async_rq), 3908 CFQ_ATTR(slice_idle), 3909 CFQ_ATTR(low_latency), 3910 CFQ_ATTR(group_isolation), 3911 __ATTR_NULL 3912}; 3913 3914static struct elevator_type iosched_cfq = { 3915 .ops = { 3916 .elevator_merge_fn = cfq_merge, 3917 .elevator_merged_fn = cfq_merged_request, 3918 .elevator_merge_req_fn = cfq_merged_requests, 3919 .elevator_allow_merge_fn = cfq_allow_merge, 3920 .elevator_bio_merged_fn = cfq_bio_merged, 3921 .elevator_dispatch_fn = cfq_dispatch_requests, 3922 .elevator_add_req_fn = cfq_insert_request, 3923 .elevator_activate_req_fn = cfq_activate_request, 3924 .elevator_deactivate_req_fn = cfq_deactivate_request, 3925 .elevator_queue_empty_fn = cfq_queue_empty, 3926 .elevator_completed_req_fn = cfq_completed_request, 3927 .elevator_former_req_fn = elv_rb_former_request, 3928 .elevator_latter_req_fn = elv_rb_latter_request, 3929 .elevator_set_req_fn = cfq_set_request, 3930 .elevator_put_req_fn = cfq_put_request, 3931 .elevator_may_queue_fn = cfq_may_queue, 3932 .elevator_init_fn = cfq_init_queue, 3933 .elevator_exit_fn = cfq_exit_queue, 3934 .trim = cfq_free_io_context, 3935 }, 3936 .elevator_attrs = cfq_attrs, 3937 .elevator_name = "cfq", 3938 .elevator_owner = THIS_MODULE, 3939}; 3940 3941#ifdef CONFIG_CFQ_GROUP_IOSCHED 3942static struct blkio_policy_type blkio_policy_cfq = { 3943 .ops = { 3944 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 3945 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 3946 }, 3947}; 3948#else 3949static struct blkio_policy_type blkio_policy_cfq; 3950#endif 3951 3952static int __init cfq_init(void) 3953{ 3954 /* 3955 * could be 0 on HZ < 1000 setups 3956 */ 3957 if (!cfq_slice_async) 3958 cfq_slice_async = 1; 3959 if (!cfq_slice_idle) 3960 cfq_slice_idle = 1; 3961 3962 if (cfq_slab_setup()) 3963 return -ENOMEM; 3964 3965 elv_register(&iosched_cfq); 3966 blkio_policy_register(&blkio_policy_cfq); 3967 3968 return 0; 3969} 3970 3971static void __exit cfq_exit(void) 3972{ 3973 DECLARE_COMPLETION_ONSTACK(all_gone); 3974 blkio_policy_unregister(&blkio_policy_cfq); 3975 elv_unregister(&iosched_cfq); 3976 ioc_gone = &all_gone; 3977 /* ioc_gone's update must be visible before reading ioc_count */ 3978 smp_wmb(); 3979 3980 /* 3981 * this also protects us from entering cfq_slab_kill() with 3982 * pending RCU callbacks 3983 */ 3984 if (elv_ioc_count_read(cfq_ioc_count)) 3985 wait_for_completion(&all_gone); 3986 cfq_slab_kill(); 3987} 3988 3989module_init(cfq_init); 3990module_exit(cfq_exit); 3991 3992MODULE_AUTHOR("Jens Axboe"); 3993MODULE_LICENSE("GPL"); 3994MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 3995