cfq-iosched.c revision 5eb46851de3904cd1be9192fdacb8d34deadc1fc
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 "cfq.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 int cfq_group_idle = HZ / 125; 34static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 35static const int cfq_hist_divisor = 4; 36 37/* 38 * offset from end of service tree 39 */ 40#define CFQ_IDLE_DELAY (HZ / 5) 41 42/* 43 * below this threshold, we consider thinktime immediate 44 */ 45#define CFQ_MIN_TT (2) 46 47#define CFQ_SLICE_SCALE (5) 48#define CFQ_HW_QUEUE_MIN (5) 49#define CFQ_SERVICE_SHIFT 12 50 51#define CFQQ_SEEK_THR (sector_t)(8 * 100) 52#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 53#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 54#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 55 56#define RQ_CIC(rq) \ 57 ((struct cfq_io_context *) (rq)->elevator_private[0]) 58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1]) 59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2]) 60 61static struct kmem_cache *cfq_pool; 62static struct kmem_cache *cfq_ioc_pool; 63 64static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); 65static struct completion *ioc_gone; 66static DEFINE_SPINLOCK(ioc_gone_lock); 67 68static DEFINE_SPINLOCK(cic_index_lock); 69static DEFINE_IDA(cic_index_ida); 70 71#define CFQ_PRIO_LISTS IOPRIO_BE_NR 72#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 73#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 74 75#define sample_valid(samples) ((samples) > 80) 76#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 77 78/* 79 * Most of our rbtree usage is for sorting with min extraction, so 80 * if we cache the leftmost node we don't have to walk down the tree 81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 82 * move this into the elevator for the rq sorting as well. 83 */ 84struct cfq_rb_root { 85 struct rb_root rb; 86 struct rb_node *left; 87 unsigned count; 88 unsigned total_weight; 89 u64 min_vdisktime; 90 struct cfq_ttime ttime; 91}; 92#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \ 93 .ttime = {.last_end_request = jiffies,},} 94 95/* 96 * Per process-grouping structure 97 */ 98struct cfq_queue { 99 /* reference count */ 100 int ref; 101 /* various state flags, see below */ 102 unsigned int flags; 103 /* parent cfq_data */ 104 struct cfq_data *cfqd; 105 /* service_tree member */ 106 struct rb_node rb_node; 107 /* service_tree key */ 108 unsigned long rb_key; 109 /* prio tree member */ 110 struct rb_node p_node; 111 /* prio tree root we belong to, if any */ 112 struct rb_root *p_root; 113 /* sorted list of pending requests */ 114 struct rb_root sort_list; 115 /* if fifo isn't expired, next request to serve */ 116 struct request *next_rq; 117 /* requests queued in sort_list */ 118 int queued[2]; 119 /* currently allocated requests */ 120 int allocated[2]; 121 /* fifo list of requests in sort_list */ 122 struct list_head fifo; 123 124 /* time when queue got scheduled in to dispatch first request. */ 125 unsigned long dispatch_start; 126 unsigned int allocated_slice; 127 unsigned int slice_dispatch; 128 /* time when first request from queue completed and slice started. */ 129 unsigned long slice_start; 130 unsigned long slice_end; 131 long slice_resid; 132 133 /* pending priority requests */ 134 int prio_pending; 135 /* number of requests that are on the dispatch list or inside driver */ 136 int dispatched; 137 138 /* io prio of this group */ 139 unsigned short ioprio, org_ioprio; 140 unsigned short ioprio_class; 141 142 pid_t pid; 143 144 u32 seek_history; 145 sector_t last_request_pos; 146 147 struct cfq_rb_root *service_tree; 148 struct cfq_queue *new_cfqq; 149 struct cfq_group *cfqg; 150 /* Number of sectors dispatched from queue in single dispatch round */ 151 unsigned long nr_sectors; 152}; 153 154/* 155 * First index in the service_trees. 156 * IDLE is handled separately, so it has negative index 157 */ 158enum wl_prio_t { 159 BE_WORKLOAD = 0, 160 RT_WORKLOAD = 1, 161 IDLE_WORKLOAD = 2, 162 CFQ_PRIO_NR, 163}; 164 165/* 166 * Second index in the service_trees. 167 */ 168enum wl_type_t { 169 ASYNC_WORKLOAD = 0, 170 SYNC_NOIDLE_WORKLOAD = 1, 171 SYNC_WORKLOAD = 2 172}; 173 174/* This is per cgroup per device grouping structure */ 175struct cfq_group { 176 /* group service_tree member */ 177 struct rb_node rb_node; 178 179 /* group service_tree key */ 180 u64 vdisktime; 181 unsigned int weight; 182 unsigned int new_weight; 183 bool needs_update; 184 185 /* number of cfqq currently on this group */ 186 int nr_cfqq; 187 188 /* 189 * Per group busy queues average. Useful for workload slice calc. We 190 * create the array for each prio class but at run time it is used 191 * only for RT and BE class and slot for IDLE class remains unused. 192 * This is primarily done to avoid confusion and a gcc warning. 193 */ 194 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 195 /* 196 * rr lists of queues with requests. We maintain service trees for 197 * RT and BE classes. These trees are subdivided in subclasses 198 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 199 * class there is no subclassification and all the cfq queues go on 200 * a single tree service_tree_idle. 201 * Counts are embedded in the cfq_rb_root 202 */ 203 struct cfq_rb_root service_trees[2][3]; 204 struct cfq_rb_root service_tree_idle; 205 206 unsigned long saved_workload_slice; 207 enum wl_type_t saved_workload; 208 enum wl_prio_t saved_serving_prio; 209 struct blkio_group blkg; 210#ifdef CONFIG_CFQ_GROUP_IOSCHED 211 struct hlist_node cfqd_node; 212 int ref; 213#endif 214 /* number of requests that are on the dispatch list or inside driver */ 215 int dispatched; 216 struct cfq_ttime ttime; 217}; 218 219/* 220 * Per block device queue structure 221 */ 222struct cfq_data { 223 struct request_queue *queue; 224 /* Root service tree for cfq_groups */ 225 struct cfq_rb_root grp_service_tree; 226 struct cfq_group root_group; 227 228 /* 229 * The priority currently being served 230 */ 231 enum wl_prio_t serving_prio; 232 enum wl_type_t serving_type; 233 unsigned long workload_expires; 234 struct cfq_group *serving_group; 235 236 /* 237 * Each priority tree is sorted by next_request position. These 238 * trees are used when determining if two or more queues are 239 * interleaving requests (see cfq_close_cooperator). 240 */ 241 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 242 243 unsigned int busy_queues; 244 unsigned int busy_sync_queues; 245 246 int rq_in_driver; 247 int rq_in_flight[2]; 248 249 /* 250 * queue-depth detection 251 */ 252 int rq_queued; 253 int hw_tag; 254 /* 255 * hw_tag can be 256 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 257 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 258 * 0 => no NCQ 259 */ 260 int hw_tag_est_depth; 261 unsigned int hw_tag_samples; 262 263 /* 264 * idle window management 265 */ 266 struct timer_list idle_slice_timer; 267 struct work_struct unplug_work; 268 269 struct cfq_queue *active_queue; 270 struct cfq_io_context *active_cic; 271 272 /* 273 * async queue for each priority case 274 */ 275 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 276 struct cfq_queue *async_idle_cfqq; 277 278 sector_t last_position; 279 280 /* 281 * tunables, see top of file 282 */ 283 unsigned int cfq_quantum; 284 unsigned int cfq_fifo_expire[2]; 285 unsigned int cfq_back_penalty; 286 unsigned int cfq_back_max; 287 unsigned int cfq_slice[2]; 288 unsigned int cfq_slice_async_rq; 289 unsigned int cfq_slice_idle; 290 unsigned int cfq_group_idle; 291 unsigned int cfq_latency; 292 293 unsigned int cic_index; 294 struct list_head cic_list; 295 296 /* 297 * Fallback dummy cfqq for extreme OOM conditions 298 */ 299 struct cfq_queue oom_cfqq; 300 301 unsigned long last_delayed_sync; 302 303 /* List of cfq groups being managed on this device*/ 304 struct hlist_head cfqg_list; 305 306 /* Number of groups which are on blkcg->blkg_list */ 307 unsigned int nr_blkcg_linked_grps; 308}; 309 310static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 311 312static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 313 enum wl_prio_t prio, 314 enum wl_type_t type) 315{ 316 if (!cfqg) 317 return NULL; 318 319 if (prio == IDLE_WORKLOAD) 320 return &cfqg->service_tree_idle; 321 322 return &cfqg->service_trees[prio][type]; 323} 324 325enum cfqq_state_flags { 326 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 327 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 328 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 329 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 330 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 331 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 332 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 333 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 334 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 335 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 336 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 337 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 338 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 339}; 340 341#define CFQ_CFQQ_FNS(name) \ 342static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 343{ \ 344 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 345} \ 346static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 347{ \ 348 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 349} \ 350static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 351{ \ 352 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 353} 354 355CFQ_CFQQ_FNS(on_rr); 356CFQ_CFQQ_FNS(wait_request); 357CFQ_CFQQ_FNS(must_dispatch); 358CFQ_CFQQ_FNS(must_alloc_slice); 359CFQ_CFQQ_FNS(fifo_expire); 360CFQ_CFQQ_FNS(idle_window); 361CFQ_CFQQ_FNS(prio_changed); 362CFQ_CFQQ_FNS(slice_new); 363CFQ_CFQQ_FNS(sync); 364CFQ_CFQQ_FNS(coop); 365CFQ_CFQQ_FNS(split_coop); 366CFQ_CFQQ_FNS(deep); 367CFQ_CFQQ_FNS(wait_busy); 368#undef CFQ_CFQQ_FNS 369 370#ifdef CONFIG_CFQ_GROUP_IOSCHED 371#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 372 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 373 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 374 blkg_path(&(cfqq)->cfqg->blkg), ##args) 375 376#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 377 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 378 blkg_path(&(cfqg)->blkg), ##args) \ 379 380#else 381#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 382 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 383#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 384#endif 385#define cfq_log(cfqd, fmt, args...) \ 386 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 387 388/* Traverses through cfq group service trees */ 389#define for_each_cfqg_st(cfqg, i, j, st) \ 390 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 391 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 392 : &cfqg->service_tree_idle; \ 393 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 394 (i == IDLE_WORKLOAD && j == 0); \ 395 j++, st = i < IDLE_WORKLOAD ? \ 396 &cfqg->service_trees[i][j]: NULL) \ 397 398static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, 399 struct cfq_ttime *ttime, bool group_idle) 400{ 401 unsigned long slice; 402 if (!sample_valid(ttime->ttime_samples)) 403 return false; 404 if (group_idle) 405 slice = cfqd->cfq_group_idle; 406 else 407 slice = cfqd->cfq_slice_idle; 408 return ttime->ttime_mean > slice; 409} 410 411static inline bool iops_mode(struct cfq_data *cfqd) 412{ 413 /* 414 * If we are not idling on queues and it is a NCQ drive, parallel 415 * execution of requests is on and measuring time is not possible 416 * in most of the cases until and unless we drive shallower queue 417 * depths and that becomes a performance bottleneck. In such cases 418 * switch to start providing fairness in terms of number of IOs. 419 */ 420 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 421 return true; 422 else 423 return false; 424} 425 426static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 427{ 428 if (cfq_class_idle(cfqq)) 429 return IDLE_WORKLOAD; 430 if (cfq_class_rt(cfqq)) 431 return RT_WORKLOAD; 432 return BE_WORKLOAD; 433} 434 435 436static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 437{ 438 if (!cfq_cfqq_sync(cfqq)) 439 return ASYNC_WORKLOAD; 440 if (!cfq_cfqq_idle_window(cfqq)) 441 return SYNC_NOIDLE_WORKLOAD; 442 return SYNC_WORKLOAD; 443} 444 445static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 446 struct cfq_data *cfqd, 447 struct cfq_group *cfqg) 448{ 449 if (wl == IDLE_WORKLOAD) 450 return cfqg->service_tree_idle.count; 451 452 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 453 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 454 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 455} 456 457static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 458 struct cfq_group *cfqg) 459{ 460 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 461 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 462} 463 464static void cfq_dispatch_insert(struct request_queue *, struct request *); 465static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, 466 struct io_context *, gfp_t); 467static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, 468 struct io_context *); 469 470static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, 471 bool is_sync) 472{ 473 return cic->cfqq[is_sync]; 474} 475 476static inline void cic_set_cfqq(struct cfq_io_context *cic, 477 struct cfq_queue *cfqq, bool is_sync) 478{ 479 cic->cfqq[is_sync] = cfqq; 480} 481 482#define CIC_DEAD_KEY 1ul 483#define CIC_DEAD_INDEX_SHIFT 1 484 485static inline void *cfqd_dead_key(struct cfq_data *cfqd) 486{ 487 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); 488} 489 490static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) 491{ 492 struct cfq_data *cfqd = cic->key; 493 494 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY)) 495 return NULL; 496 497 return cfqd; 498} 499 500/* 501 * We regard a request as SYNC, if it's either a read or has the SYNC bit 502 * set (in which case it could also be direct WRITE). 503 */ 504static inline bool cfq_bio_sync(struct bio *bio) 505{ 506 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 507} 508 509/* 510 * scheduler run of queue, if there are requests pending and no one in the 511 * driver that will restart queueing 512 */ 513static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 514{ 515 if (cfqd->busy_queues) { 516 cfq_log(cfqd, "schedule dispatch"); 517 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 518 } 519} 520 521/* 522 * Scale schedule slice based on io priority. Use the sync time slice only 523 * if a queue is marked sync and has sync io queued. A sync queue with async 524 * io only, should not get full sync slice length. 525 */ 526static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 527 unsigned short prio) 528{ 529 const int base_slice = cfqd->cfq_slice[sync]; 530 531 WARN_ON(prio >= IOPRIO_BE_NR); 532 533 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 534} 535 536static inline int 537cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 538{ 539 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 540} 541 542static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 543{ 544 u64 d = delta << CFQ_SERVICE_SHIFT; 545 546 d = d * BLKIO_WEIGHT_DEFAULT; 547 do_div(d, cfqg->weight); 548 return d; 549} 550 551static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 552{ 553 s64 delta = (s64)(vdisktime - min_vdisktime); 554 if (delta > 0) 555 min_vdisktime = vdisktime; 556 557 return min_vdisktime; 558} 559 560static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 561{ 562 s64 delta = (s64)(vdisktime - min_vdisktime); 563 if (delta < 0) 564 min_vdisktime = vdisktime; 565 566 return min_vdisktime; 567} 568 569static void update_min_vdisktime(struct cfq_rb_root *st) 570{ 571 struct cfq_group *cfqg; 572 573 if (st->left) { 574 cfqg = rb_entry_cfqg(st->left); 575 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 576 cfqg->vdisktime); 577 } 578} 579 580/* 581 * get averaged number of queues of RT/BE priority. 582 * average is updated, with a formula that gives more weight to higher numbers, 583 * to quickly follows sudden increases and decrease slowly 584 */ 585 586static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 587 struct cfq_group *cfqg, bool rt) 588{ 589 unsigned min_q, max_q; 590 unsigned mult = cfq_hist_divisor - 1; 591 unsigned round = cfq_hist_divisor / 2; 592 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 593 594 min_q = min(cfqg->busy_queues_avg[rt], busy); 595 max_q = max(cfqg->busy_queues_avg[rt], busy); 596 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 597 cfq_hist_divisor; 598 return cfqg->busy_queues_avg[rt]; 599} 600 601static inline unsigned 602cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 603{ 604 struct cfq_rb_root *st = &cfqd->grp_service_tree; 605 606 return cfq_target_latency * cfqg->weight / st->total_weight; 607} 608 609static inline unsigned 610cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 611{ 612 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 613 if (cfqd->cfq_latency) { 614 /* 615 * interested queues (we consider only the ones with the same 616 * priority class in the cfq group) 617 */ 618 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 619 cfq_class_rt(cfqq)); 620 unsigned sync_slice = cfqd->cfq_slice[1]; 621 unsigned expect_latency = sync_slice * iq; 622 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 623 624 if (expect_latency > group_slice) { 625 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 626 /* scale low_slice according to IO priority 627 * and sync vs async */ 628 unsigned low_slice = 629 min(slice, base_low_slice * slice / sync_slice); 630 /* the adapted slice value is scaled to fit all iqs 631 * into the target latency */ 632 slice = max(slice * group_slice / expect_latency, 633 low_slice); 634 } 635 } 636 return slice; 637} 638 639static inline void 640cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 641{ 642 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 643 644 cfqq->slice_start = jiffies; 645 cfqq->slice_end = jiffies + slice; 646 cfqq->allocated_slice = slice; 647 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 648} 649 650/* 651 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 652 * isn't valid until the first request from the dispatch is activated 653 * and the slice time set. 654 */ 655static inline bool cfq_slice_used(struct cfq_queue *cfqq) 656{ 657 if (cfq_cfqq_slice_new(cfqq)) 658 return false; 659 if (time_before(jiffies, cfqq->slice_end)) 660 return false; 661 662 return true; 663} 664 665/* 666 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 667 * We choose the request that is closest to the head right now. Distance 668 * behind the head is penalized and only allowed to a certain extent. 669 */ 670static struct request * 671cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 672{ 673 sector_t s1, s2, d1 = 0, d2 = 0; 674 unsigned long back_max; 675#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 676#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 677 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 678 679 if (rq1 == NULL || rq1 == rq2) 680 return rq2; 681 if (rq2 == NULL) 682 return rq1; 683 684 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 685 return rq_is_sync(rq1) ? rq1 : rq2; 686 687 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) 688 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; 689 690 s1 = blk_rq_pos(rq1); 691 s2 = blk_rq_pos(rq2); 692 693 /* 694 * by definition, 1KiB is 2 sectors 695 */ 696 back_max = cfqd->cfq_back_max * 2; 697 698 /* 699 * Strict one way elevator _except_ in the case where we allow 700 * short backward seeks which are biased as twice the cost of a 701 * similar forward seek. 702 */ 703 if (s1 >= last) 704 d1 = s1 - last; 705 else if (s1 + back_max >= last) 706 d1 = (last - s1) * cfqd->cfq_back_penalty; 707 else 708 wrap |= CFQ_RQ1_WRAP; 709 710 if (s2 >= last) 711 d2 = s2 - last; 712 else if (s2 + back_max >= last) 713 d2 = (last - s2) * cfqd->cfq_back_penalty; 714 else 715 wrap |= CFQ_RQ2_WRAP; 716 717 /* Found required data */ 718 719 /* 720 * By doing switch() on the bit mask "wrap" we avoid having to 721 * check two variables for all permutations: --> faster! 722 */ 723 switch (wrap) { 724 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 725 if (d1 < d2) 726 return rq1; 727 else if (d2 < d1) 728 return rq2; 729 else { 730 if (s1 >= s2) 731 return rq1; 732 else 733 return rq2; 734 } 735 736 case CFQ_RQ2_WRAP: 737 return rq1; 738 case CFQ_RQ1_WRAP: 739 return rq2; 740 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 741 default: 742 /* 743 * Since both rqs are wrapped, 744 * start with the one that's further behind head 745 * (--> only *one* back seek required), 746 * since back seek takes more time than forward. 747 */ 748 if (s1 <= s2) 749 return rq1; 750 else 751 return rq2; 752 } 753} 754 755/* 756 * The below is leftmost cache rbtree addon 757 */ 758static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 759{ 760 /* Service tree is empty */ 761 if (!root->count) 762 return NULL; 763 764 if (!root->left) 765 root->left = rb_first(&root->rb); 766 767 if (root->left) 768 return rb_entry(root->left, struct cfq_queue, rb_node); 769 770 return NULL; 771} 772 773static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 774{ 775 if (!root->left) 776 root->left = rb_first(&root->rb); 777 778 if (root->left) 779 return rb_entry_cfqg(root->left); 780 781 return NULL; 782} 783 784static void rb_erase_init(struct rb_node *n, struct rb_root *root) 785{ 786 rb_erase(n, root); 787 RB_CLEAR_NODE(n); 788} 789 790static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 791{ 792 if (root->left == n) 793 root->left = NULL; 794 rb_erase_init(n, &root->rb); 795 --root->count; 796} 797 798/* 799 * would be nice to take fifo expire time into account as well 800 */ 801static struct request * 802cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 803 struct request *last) 804{ 805 struct rb_node *rbnext = rb_next(&last->rb_node); 806 struct rb_node *rbprev = rb_prev(&last->rb_node); 807 struct request *next = NULL, *prev = NULL; 808 809 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 810 811 if (rbprev) 812 prev = rb_entry_rq(rbprev); 813 814 if (rbnext) 815 next = rb_entry_rq(rbnext); 816 else { 817 rbnext = rb_first(&cfqq->sort_list); 818 if (rbnext && rbnext != &last->rb_node) 819 next = rb_entry_rq(rbnext); 820 } 821 822 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 823} 824 825static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 826 struct cfq_queue *cfqq) 827{ 828 /* 829 * just an approximation, should be ok. 830 */ 831 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 832 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 833} 834 835static inline s64 836cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 837{ 838 return cfqg->vdisktime - st->min_vdisktime; 839} 840 841static void 842__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 843{ 844 struct rb_node **node = &st->rb.rb_node; 845 struct rb_node *parent = NULL; 846 struct cfq_group *__cfqg; 847 s64 key = cfqg_key(st, cfqg); 848 int left = 1; 849 850 while (*node != NULL) { 851 parent = *node; 852 __cfqg = rb_entry_cfqg(parent); 853 854 if (key < cfqg_key(st, __cfqg)) 855 node = &parent->rb_left; 856 else { 857 node = &parent->rb_right; 858 left = 0; 859 } 860 } 861 862 if (left) 863 st->left = &cfqg->rb_node; 864 865 rb_link_node(&cfqg->rb_node, parent, node); 866 rb_insert_color(&cfqg->rb_node, &st->rb); 867} 868 869static void 870cfq_update_group_weight(struct cfq_group *cfqg) 871{ 872 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 873 if (cfqg->needs_update) { 874 cfqg->weight = cfqg->new_weight; 875 cfqg->needs_update = false; 876 } 877} 878 879static void 880cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 881{ 882 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 883 884 cfq_update_group_weight(cfqg); 885 __cfq_group_service_tree_add(st, cfqg); 886 st->total_weight += cfqg->weight; 887} 888 889static void 890cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 891{ 892 struct cfq_rb_root *st = &cfqd->grp_service_tree; 893 struct cfq_group *__cfqg; 894 struct rb_node *n; 895 896 cfqg->nr_cfqq++; 897 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 898 return; 899 900 /* 901 * Currently put the group at the end. Later implement something 902 * so that groups get lesser vtime based on their weights, so that 903 * if group does not loose all if it was not continuously backlogged. 904 */ 905 n = rb_last(&st->rb); 906 if (n) { 907 __cfqg = rb_entry_cfqg(n); 908 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 909 } else 910 cfqg->vdisktime = st->min_vdisktime; 911 cfq_group_service_tree_add(st, cfqg); 912} 913 914static void 915cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 916{ 917 st->total_weight -= cfqg->weight; 918 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 919 cfq_rb_erase(&cfqg->rb_node, st); 920} 921 922static void 923cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 924{ 925 struct cfq_rb_root *st = &cfqd->grp_service_tree; 926 927 BUG_ON(cfqg->nr_cfqq < 1); 928 cfqg->nr_cfqq--; 929 930 /* If there are other cfq queues under this group, don't delete it */ 931 if (cfqg->nr_cfqq) 932 return; 933 934 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 935 cfq_group_service_tree_del(st, cfqg); 936 cfqg->saved_workload_slice = 0; 937 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); 938} 939 940static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 941 unsigned int *unaccounted_time) 942{ 943 unsigned int slice_used; 944 945 /* 946 * Queue got expired before even a single request completed or 947 * got expired immediately after first request completion. 948 */ 949 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 950 /* 951 * Also charge the seek time incurred to the group, otherwise 952 * if there are mutiple queues in the group, each can dispatch 953 * a single request on seeky media and cause lots of seek time 954 * and group will never know it. 955 */ 956 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 957 1); 958 } else { 959 slice_used = jiffies - cfqq->slice_start; 960 if (slice_used > cfqq->allocated_slice) { 961 *unaccounted_time = slice_used - cfqq->allocated_slice; 962 slice_used = cfqq->allocated_slice; 963 } 964 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 965 *unaccounted_time += cfqq->slice_start - 966 cfqq->dispatch_start; 967 } 968 969 return slice_used; 970} 971 972static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 973 struct cfq_queue *cfqq) 974{ 975 struct cfq_rb_root *st = &cfqd->grp_service_tree; 976 unsigned int used_sl, charge, unaccounted_sl = 0; 977 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 978 - cfqg->service_tree_idle.count; 979 980 BUG_ON(nr_sync < 0); 981 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 982 983 if (iops_mode(cfqd)) 984 charge = cfqq->slice_dispatch; 985 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 986 charge = cfqq->allocated_slice; 987 988 /* Can't update vdisktime while group is on service tree */ 989 cfq_group_service_tree_del(st, cfqg); 990 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 991 /* If a new weight was requested, update now, off tree */ 992 cfq_group_service_tree_add(st, cfqg); 993 994 /* This group is being expired. Save the context */ 995 if (time_after(cfqd->workload_expires, jiffies)) { 996 cfqg->saved_workload_slice = cfqd->workload_expires 997 - jiffies; 998 cfqg->saved_workload = cfqd->serving_type; 999 cfqg->saved_serving_prio = cfqd->serving_prio; 1000 } else 1001 cfqg->saved_workload_slice = 0; 1002 1003 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 1004 st->min_vdisktime); 1005 cfq_log_cfqq(cfqq->cfqd, cfqq, 1006 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 1007 used_sl, cfqq->slice_dispatch, charge, 1008 iops_mode(cfqd), cfqq->nr_sectors); 1009 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, 1010 unaccounted_sl); 1011 cfq_blkiocg_set_start_empty_time(&cfqg->blkg); 1012} 1013 1014#ifdef CONFIG_CFQ_GROUP_IOSCHED 1015static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 1016{ 1017 if (blkg) 1018 return container_of(blkg, struct cfq_group, blkg); 1019 return NULL; 1020} 1021 1022static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, 1023 unsigned int weight) 1024{ 1025 struct cfq_group *cfqg = cfqg_of_blkg(blkg); 1026 cfqg->new_weight = weight; 1027 cfqg->needs_update = true; 1028} 1029 1030static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, 1031 struct cfq_group *cfqg, struct blkio_cgroup *blkcg) 1032{ 1033 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1034 unsigned int major, minor; 1035 1036 /* 1037 * Add group onto cgroup list. It might happen that bdi->dev is 1038 * not initialized yet. Initialize this new group without major 1039 * and minor info and this info will be filled in once a new thread 1040 * comes for IO. 1041 */ 1042 if (bdi->dev) { 1043 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1044 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1045 (void *)cfqd, MKDEV(major, minor)); 1046 } else 1047 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1048 (void *)cfqd, 0); 1049 1050 cfqd->nr_blkcg_linked_grps++; 1051 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); 1052 1053 /* Add group on cfqd list */ 1054 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 1055} 1056 1057/* 1058 * Should be called from sleepable context. No request queue lock as per 1059 * cpu stats are allocated dynamically and alloc_percpu needs to be called 1060 * from sleepable context. 1061 */ 1062static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) 1063{ 1064 struct cfq_group *cfqg = NULL; 1065 int i, j, ret; 1066 struct cfq_rb_root *st; 1067 1068 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 1069 if (!cfqg) 1070 return NULL; 1071 1072 for_each_cfqg_st(cfqg, i, j, st) 1073 *st = CFQ_RB_ROOT; 1074 RB_CLEAR_NODE(&cfqg->rb_node); 1075 1076 cfqg->ttime.last_end_request = jiffies; 1077 1078 /* 1079 * Take the initial reference that will be released on destroy 1080 * This can be thought of a joint reference by cgroup and 1081 * elevator which will be dropped by either elevator exit 1082 * or cgroup deletion path depending on who is exiting first. 1083 */ 1084 cfqg->ref = 1; 1085 1086 ret = blkio_alloc_blkg_stats(&cfqg->blkg); 1087 if (ret) { 1088 kfree(cfqg); 1089 return NULL; 1090 } 1091 1092 return cfqg; 1093} 1094 1095static struct cfq_group * 1096cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) 1097{ 1098 struct cfq_group *cfqg = NULL; 1099 void *key = cfqd; 1100 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1101 unsigned int major, minor; 1102 1103 /* 1104 * This is the common case when there are no blkio cgroups. 1105 * Avoid lookup in this case 1106 */ 1107 if (blkcg == &blkio_root_cgroup) 1108 cfqg = &cfqd->root_group; 1109 else 1110 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); 1111 1112 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { 1113 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1114 cfqg->blkg.dev = MKDEV(major, minor); 1115 } 1116 1117 return cfqg; 1118} 1119 1120/* 1121 * Search for the cfq group current task belongs to. request_queue lock must 1122 * be held. 1123 */ 1124static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1125{ 1126 struct blkio_cgroup *blkcg; 1127 struct cfq_group *cfqg = NULL, *__cfqg = NULL; 1128 struct request_queue *q = cfqd->queue; 1129 1130 rcu_read_lock(); 1131 blkcg = task_blkio_cgroup(current); 1132 cfqg = cfq_find_cfqg(cfqd, blkcg); 1133 if (cfqg) { 1134 rcu_read_unlock(); 1135 return cfqg; 1136 } 1137 1138 /* 1139 * Need to allocate a group. Allocation of group also needs allocation 1140 * of per cpu stats which in-turn takes a mutex() and can block. Hence 1141 * we need to drop rcu lock and queue_lock before we call alloc. 1142 * 1143 * Not taking any queue reference here and assuming that queue is 1144 * around by the time we return. CFQ queue allocation code does 1145 * the same. It might be racy though. 1146 */ 1147 1148 rcu_read_unlock(); 1149 spin_unlock_irq(q->queue_lock); 1150 1151 cfqg = cfq_alloc_cfqg(cfqd); 1152 1153 spin_lock_irq(q->queue_lock); 1154 1155 rcu_read_lock(); 1156 blkcg = task_blkio_cgroup(current); 1157 1158 /* 1159 * If some other thread already allocated the group while we were 1160 * not holding queue lock, free up the group 1161 */ 1162 __cfqg = cfq_find_cfqg(cfqd, blkcg); 1163 1164 if (__cfqg) { 1165 kfree(cfqg); 1166 rcu_read_unlock(); 1167 return __cfqg; 1168 } 1169 1170 if (!cfqg) 1171 cfqg = &cfqd->root_group; 1172 1173 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); 1174 rcu_read_unlock(); 1175 return cfqg; 1176} 1177 1178static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1179{ 1180 cfqg->ref++; 1181 return cfqg; 1182} 1183 1184static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1185{ 1186 /* Currently, all async queues are mapped to root group */ 1187 if (!cfq_cfqq_sync(cfqq)) 1188 cfqg = &cfqq->cfqd->root_group; 1189 1190 cfqq->cfqg = cfqg; 1191 /* cfqq reference on cfqg */ 1192 cfqq->cfqg->ref++; 1193} 1194 1195static void cfq_put_cfqg(struct cfq_group *cfqg) 1196{ 1197 struct cfq_rb_root *st; 1198 int i, j; 1199 1200 BUG_ON(cfqg->ref <= 0); 1201 cfqg->ref--; 1202 if (cfqg->ref) 1203 return; 1204 for_each_cfqg_st(cfqg, i, j, st) 1205 BUG_ON(!RB_EMPTY_ROOT(&st->rb)); 1206 free_percpu(cfqg->blkg.stats_cpu); 1207 kfree(cfqg); 1208} 1209 1210static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1211{ 1212 /* Something wrong if we are trying to remove same group twice */ 1213 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1214 1215 hlist_del_init(&cfqg->cfqd_node); 1216 1217 BUG_ON(cfqd->nr_blkcg_linked_grps <= 0); 1218 cfqd->nr_blkcg_linked_grps--; 1219 1220 /* 1221 * Put the reference taken at the time of creation so that when all 1222 * queues are gone, group can be destroyed. 1223 */ 1224 cfq_put_cfqg(cfqg); 1225} 1226 1227static void cfq_release_cfq_groups(struct cfq_data *cfqd) 1228{ 1229 struct hlist_node *pos, *n; 1230 struct cfq_group *cfqg; 1231 1232 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1233 /* 1234 * If cgroup removal path got to blk_group first and removed 1235 * it from cgroup list, then it will take care of destroying 1236 * cfqg also. 1237 */ 1238 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) 1239 cfq_destroy_cfqg(cfqd, cfqg); 1240 } 1241} 1242 1243/* 1244 * Blk cgroup controller notification saying that blkio_group object is being 1245 * delinked as associated cgroup object is going away. That also means that 1246 * no new IO will come in this group. So get rid of this group as soon as 1247 * any pending IO in the group is finished. 1248 * 1249 * This function is called under rcu_read_lock(). key is the rcu protected 1250 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu 1251 * read lock. 1252 * 1253 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means 1254 * it should not be NULL as even if elevator was exiting, cgroup deltion 1255 * path got to it first. 1256 */ 1257static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) 1258{ 1259 unsigned long flags; 1260 struct cfq_data *cfqd = key; 1261 1262 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 1263 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1264 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 1265} 1266 1267#else /* GROUP_IOSCHED */ 1268static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1269{ 1270 return &cfqd->root_group; 1271} 1272 1273static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1274{ 1275 return cfqg; 1276} 1277 1278static inline void 1279cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1280 cfqq->cfqg = cfqg; 1281} 1282 1283static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1284static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1285 1286#endif /* GROUP_IOSCHED */ 1287 1288/* 1289 * The cfqd->service_trees holds all pending cfq_queue's that have 1290 * requests waiting to be processed. It is sorted in the order that 1291 * we will service the queues. 1292 */ 1293static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1294 bool add_front) 1295{ 1296 struct rb_node **p, *parent; 1297 struct cfq_queue *__cfqq; 1298 unsigned long rb_key; 1299 struct cfq_rb_root *service_tree; 1300 int left; 1301 int new_cfqq = 1; 1302 1303 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1304 cfqq_type(cfqq)); 1305 if (cfq_class_idle(cfqq)) { 1306 rb_key = CFQ_IDLE_DELAY; 1307 parent = rb_last(&service_tree->rb); 1308 if (parent && parent != &cfqq->rb_node) { 1309 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1310 rb_key += __cfqq->rb_key; 1311 } else 1312 rb_key += jiffies; 1313 } else if (!add_front) { 1314 /* 1315 * Get our rb key offset. Subtract any residual slice 1316 * value carried from last service. A negative resid 1317 * count indicates slice overrun, and this should position 1318 * the next service time further away in the tree. 1319 */ 1320 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1321 rb_key -= cfqq->slice_resid; 1322 cfqq->slice_resid = 0; 1323 } else { 1324 rb_key = -HZ; 1325 __cfqq = cfq_rb_first(service_tree); 1326 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1327 } 1328 1329 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1330 new_cfqq = 0; 1331 /* 1332 * same position, nothing more to do 1333 */ 1334 if (rb_key == cfqq->rb_key && 1335 cfqq->service_tree == service_tree) 1336 return; 1337 1338 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1339 cfqq->service_tree = NULL; 1340 } 1341 1342 left = 1; 1343 parent = NULL; 1344 cfqq->service_tree = service_tree; 1345 p = &service_tree->rb.rb_node; 1346 while (*p) { 1347 struct rb_node **n; 1348 1349 parent = *p; 1350 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1351 1352 /* 1353 * sort by key, that represents service time. 1354 */ 1355 if (time_before(rb_key, __cfqq->rb_key)) 1356 n = &(*p)->rb_left; 1357 else { 1358 n = &(*p)->rb_right; 1359 left = 0; 1360 } 1361 1362 p = n; 1363 } 1364 1365 if (left) 1366 service_tree->left = &cfqq->rb_node; 1367 1368 cfqq->rb_key = rb_key; 1369 rb_link_node(&cfqq->rb_node, parent, p); 1370 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1371 service_tree->count++; 1372 if (add_front || !new_cfqq) 1373 return; 1374 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1375} 1376 1377static struct cfq_queue * 1378cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1379 sector_t sector, struct rb_node **ret_parent, 1380 struct rb_node ***rb_link) 1381{ 1382 struct rb_node **p, *parent; 1383 struct cfq_queue *cfqq = NULL; 1384 1385 parent = NULL; 1386 p = &root->rb_node; 1387 while (*p) { 1388 struct rb_node **n; 1389 1390 parent = *p; 1391 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1392 1393 /* 1394 * Sort strictly based on sector. Smallest to the left, 1395 * largest to the right. 1396 */ 1397 if (sector > blk_rq_pos(cfqq->next_rq)) 1398 n = &(*p)->rb_right; 1399 else if (sector < blk_rq_pos(cfqq->next_rq)) 1400 n = &(*p)->rb_left; 1401 else 1402 break; 1403 p = n; 1404 cfqq = NULL; 1405 } 1406 1407 *ret_parent = parent; 1408 if (rb_link) 1409 *rb_link = p; 1410 return cfqq; 1411} 1412 1413static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1414{ 1415 struct rb_node **p, *parent; 1416 struct cfq_queue *__cfqq; 1417 1418 if (cfqq->p_root) { 1419 rb_erase(&cfqq->p_node, cfqq->p_root); 1420 cfqq->p_root = NULL; 1421 } 1422 1423 if (cfq_class_idle(cfqq)) 1424 return; 1425 if (!cfqq->next_rq) 1426 return; 1427 1428 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1429 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1430 blk_rq_pos(cfqq->next_rq), &parent, &p); 1431 if (!__cfqq) { 1432 rb_link_node(&cfqq->p_node, parent, p); 1433 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1434 } else 1435 cfqq->p_root = NULL; 1436} 1437 1438/* 1439 * Update cfqq's position in the service tree. 1440 */ 1441static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1442{ 1443 /* 1444 * Resorting requires the cfqq to be on the RR list already. 1445 */ 1446 if (cfq_cfqq_on_rr(cfqq)) { 1447 cfq_service_tree_add(cfqd, cfqq, 0); 1448 cfq_prio_tree_add(cfqd, cfqq); 1449 } 1450} 1451 1452/* 1453 * add to busy list of queues for service, trying to be fair in ordering 1454 * the pending list according to last request service 1455 */ 1456static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1457{ 1458 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1459 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1460 cfq_mark_cfqq_on_rr(cfqq); 1461 cfqd->busy_queues++; 1462 if (cfq_cfqq_sync(cfqq)) 1463 cfqd->busy_sync_queues++; 1464 1465 cfq_resort_rr_list(cfqd, cfqq); 1466} 1467 1468/* 1469 * Called when the cfqq no longer has requests pending, remove it from 1470 * the service tree. 1471 */ 1472static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1473{ 1474 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1475 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1476 cfq_clear_cfqq_on_rr(cfqq); 1477 1478 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1479 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1480 cfqq->service_tree = NULL; 1481 } 1482 if (cfqq->p_root) { 1483 rb_erase(&cfqq->p_node, cfqq->p_root); 1484 cfqq->p_root = NULL; 1485 } 1486 1487 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1488 BUG_ON(!cfqd->busy_queues); 1489 cfqd->busy_queues--; 1490 if (cfq_cfqq_sync(cfqq)) 1491 cfqd->busy_sync_queues--; 1492} 1493 1494/* 1495 * rb tree support functions 1496 */ 1497static void cfq_del_rq_rb(struct request *rq) 1498{ 1499 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1500 const int sync = rq_is_sync(rq); 1501 1502 BUG_ON(!cfqq->queued[sync]); 1503 cfqq->queued[sync]--; 1504 1505 elv_rb_del(&cfqq->sort_list, rq); 1506 1507 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1508 /* 1509 * Queue will be deleted from service tree when we actually 1510 * expire it later. Right now just remove it from prio tree 1511 * as it is empty. 1512 */ 1513 if (cfqq->p_root) { 1514 rb_erase(&cfqq->p_node, cfqq->p_root); 1515 cfqq->p_root = NULL; 1516 } 1517 } 1518} 1519 1520static void cfq_add_rq_rb(struct request *rq) 1521{ 1522 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1523 struct cfq_data *cfqd = cfqq->cfqd; 1524 struct request *prev; 1525 1526 cfqq->queued[rq_is_sync(rq)]++; 1527 1528 elv_rb_add(&cfqq->sort_list, rq); 1529 1530 if (!cfq_cfqq_on_rr(cfqq)) 1531 cfq_add_cfqq_rr(cfqd, cfqq); 1532 1533 /* 1534 * check if this request is a better next-serve candidate 1535 */ 1536 prev = cfqq->next_rq; 1537 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1538 1539 /* 1540 * adjust priority tree position, if ->next_rq changes 1541 */ 1542 if (prev != cfqq->next_rq) 1543 cfq_prio_tree_add(cfqd, cfqq); 1544 1545 BUG_ON(!cfqq->next_rq); 1546} 1547 1548static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1549{ 1550 elv_rb_del(&cfqq->sort_list, rq); 1551 cfqq->queued[rq_is_sync(rq)]--; 1552 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1553 rq_data_dir(rq), rq_is_sync(rq)); 1554 cfq_add_rq_rb(rq); 1555 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 1556 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), 1557 rq_is_sync(rq)); 1558} 1559 1560static struct request * 1561cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1562{ 1563 struct task_struct *tsk = current; 1564 struct cfq_io_context *cic; 1565 struct cfq_queue *cfqq; 1566 1567 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1568 if (!cic) 1569 return NULL; 1570 1571 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1572 if (cfqq) { 1573 sector_t sector = bio->bi_sector + bio_sectors(bio); 1574 1575 return elv_rb_find(&cfqq->sort_list, sector); 1576 } 1577 1578 return NULL; 1579} 1580 1581static void cfq_activate_request(struct request_queue *q, struct request *rq) 1582{ 1583 struct cfq_data *cfqd = q->elevator->elevator_data; 1584 1585 cfqd->rq_in_driver++; 1586 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1587 cfqd->rq_in_driver); 1588 1589 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1590} 1591 1592static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1593{ 1594 struct cfq_data *cfqd = q->elevator->elevator_data; 1595 1596 WARN_ON(!cfqd->rq_in_driver); 1597 cfqd->rq_in_driver--; 1598 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1599 cfqd->rq_in_driver); 1600} 1601 1602static void cfq_remove_request(struct request *rq) 1603{ 1604 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1605 1606 if (cfqq->next_rq == rq) 1607 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1608 1609 list_del_init(&rq->queuelist); 1610 cfq_del_rq_rb(rq); 1611 1612 cfqq->cfqd->rq_queued--; 1613 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1614 rq_data_dir(rq), rq_is_sync(rq)); 1615 if (rq->cmd_flags & REQ_PRIO) { 1616 WARN_ON(!cfqq->prio_pending); 1617 cfqq->prio_pending--; 1618 } 1619} 1620 1621static int cfq_merge(struct request_queue *q, struct request **req, 1622 struct bio *bio) 1623{ 1624 struct cfq_data *cfqd = q->elevator->elevator_data; 1625 struct request *__rq; 1626 1627 __rq = cfq_find_rq_fmerge(cfqd, bio); 1628 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1629 *req = __rq; 1630 return ELEVATOR_FRONT_MERGE; 1631 } 1632 1633 return ELEVATOR_NO_MERGE; 1634} 1635 1636static void cfq_merged_request(struct request_queue *q, struct request *req, 1637 int type) 1638{ 1639 if (type == ELEVATOR_FRONT_MERGE) { 1640 struct cfq_queue *cfqq = RQ_CFQQ(req); 1641 1642 cfq_reposition_rq_rb(cfqq, req); 1643 } 1644} 1645 1646static void cfq_bio_merged(struct request_queue *q, struct request *req, 1647 struct bio *bio) 1648{ 1649 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, 1650 bio_data_dir(bio), cfq_bio_sync(bio)); 1651} 1652 1653static void 1654cfq_merged_requests(struct request_queue *q, struct request *rq, 1655 struct request *next) 1656{ 1657 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1658 /* 1659 * reposition in fifo if next is older than rq 1660 */ 1661 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1662 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1663 list_move(&rq->queuelist, &next->queuelist); 1664 rq_set_fifo_time(rq, rq_fifo_time(next)); 1665 } 1666 1667 if (cfqq->next_rq == next) 1668 cfqq->next_rq = rq; 1669 cfq_remove_request(next); 1670 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, 1671 rq_data_dir(next), rq_is_sync(next)); 1672} 1673 1674static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1675 struct bio *bio) 1676{ 1677 struct cfq_data *cfqd = q->elevator->elevator_data; 1678 struct cfq_io_context *cic; 1679 struct cfq_queue *cfqq; 1680 1681 /* 1682 * Disallow merge of a sync bio into an async request. 1683 */ 1684 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1685 return false; 1686 1687 /* 1688 * Lookup the cfqq that this bio will be queued with. Allow 1689 * merge only if rq is queued there. 1690 */ 1691 cic = cfq_cic_lookup(cfqd, current->io_context); 1692 if (!cic) 1693 return false; 1694 1695 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1696 return cfqq == RQ_CFQQ(rq); 1697} 1698 1699static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1700{ 1701 del_timer(&cfqd->idle_slice_timer); 1702 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); 1703} 1704 1705static void __cfq_set_active_queue(struct cfq_data *cfqd, 1706 struct cfq_queue *cfqq) 1707{ 1708 if (cfqq) { 1709 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1710 cfqd->serving_prio, cfqd->serving_type); 1711 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); 1712 cfqq->slice_start = 0; 1713 cfqq->dispatch_start = jiffies; 1714 cfqq->allocated_slice = 0; 1715 cfqq->slice_end = 0; 1716 cfqq->slice_dispatch = 0; 1717 cfqq->nr_sectors = 0; 1718 1719 cfq_clear_cfqq_wait_request(cfqq); 1720 cfq_clear_cfqq_must_dispatch(cfqq); 1721 cfq_clear_cfqq_must_alloc_slice(cfqq); 1722 cfq_clear_cfqq_fifo_expire(cfqq); 1723 cfq_mark_cfqq_slice_new(cfqq); 1724 1725 cfq_del_timer(cfqd, cfqq); 1726 } 1727 1728 cfqd->active_queue = cfqq; 1729} 1730 1731/* 1732 * current cfqq expired its slice (or was too idle), select new one 1733 */ 1734static void 1735__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1736 bool timed_out) 1737{ 1738 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1739 1740 if (cfq_cfqq_wait_request(cfqq)) 1741 cfq_del_timer(cfqd, cfqq); 1742 1743 cfq_clear_cfqq_wait_request(cfqq); 1744 cfq_clear_cfqq_wait_busy(cfqq); 1745 1746 /* 1747 * If this cfqq is shared between multiple processes, check to 1748 * make sure that those processes are still issuing I/Os within 1749 * the mean seek distance. If not, it may be time to break the 1750 * queues apart again. 1751 */ 1752 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1753 cfq_mark_cfqq_split_coop(cfqq); 1754 1755 /* 1756 * store what was left of this slice, if the queue idled/timed out 1757 */ 1758 if (timed_out) { 1759 if (cfq_cfqq_slice_new(cfqq)) 1760 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 1761 else 1762 cfqq->slice_resid = cfqq->slice_end - jiffies; 1763 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1764 } 1765 1766 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1767 1768 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1769 cfq_del_cfqq_rr(cfqd, cfqq); 1770 1771 cfq_resort_rr_list(cfqd, cfqq); 1772 1773 if (cfqq == cfqd->active_queue) 1774 cfqd->active_queue = NULL; 1775 1776 if (cfqd->active_cic) { 1777 put_io_context(cfqd->active_cic->ioc); 1778 cfqd->active_cic = NULL; 1779 } 1780} 1781 1782static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1783{ 1784 struct cfq_queue *cfqq = cfqd->active_queue; 1785 1786 if (cfqq) 1787 __cfq_slice_expired(cfqd, cfqq, timed_out); 1788} 1789 1790/* 1791 * Get next queue for service. Unless we have a queue preemption, 1792 * we'll simply select the first cfqq in the service tree. 1793 */ 1794static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1795{ 1796 struct cfq_rb_root *service_tree = 1797 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1798 cfqd->serving_type); 1799 1800 if (!cfqd->rq_queued) 1801 return NULL; 1802 1803 /* There is nothing to dispatch */ 1804 if (!service_tree) 1805 return NULL; 1806 if (RB_EMPTY_ROOT(&service_tree->rb)) 1807 return NULL; 1808 return cfq_rb_first(service_tree); 1809} 1810 1811static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1812{ 1813 struct cfq_group *cfqg; 1814 struct cfq_queue *cfqq; 1815 int i, j; 1816 struct cfq_rb_root *st; 1817 1818 if (!cfqd->rq_queued) 1819 return NULL; 1820 1821 cfqg = cfq_get_next_cfqg(cfqd); 1822 if (!cfqg) 1823 return NULL; 1824 1825 for_each_cfqg_st(cfqg, i, j, st) 1826 if ((cfqq = cfq_rb_first(st)) != NULL) 1827 return cfqq; 1828 return NULL; 1829} 1830 1831/* 1832 * Get and set a new active queue for service. 1833 */ 1834static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1835 struct cfq_queue *cfqq) 1836{ 1837 if (!cfqq) 1838 cfqq = cfq_get_next_queue(cfqd); 1839 1840 __cfq_set_active_queue(cfqd, cfqq); 1841 return cfqq; 1842} 1843 1844static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1845 struct request *rq) 1846{ 1847 if (blk_rq_pos(rq) >= cfqd->last_position) 1848 return blk_rq_pos(rq) - cfqd->last_position; 1849 else 1850 return cfqd->last_position - blk_rq_pos(rq); 1851} 1852 1853static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1854 struct request *rq) 1855{ 1856 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1857} 1858 1859static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1860 struct cfq_queue *cur_cfqq) 1861{ 1862 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1863 struct rb_node *parent, *node; 1864 struct cfq_queue *__cfqq; 1865 sector_t sector = cfqd->last_position; 1866 1867 if (RB_EMPTY_ROOT(root)) 1868 return NULL; 1869 1870 /* 1871 * First, if we find a request starting at the end of the last 1872 * request, choose it. 1873 */ 1874 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1875 if (__cfqq) 1876 return __cfqq; 1877 1878 /* 1879 * If the exact sector wasn't found, the parent of the NULL leaf 1880 * will contain the closest sector. 1881 */ 1882 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1883 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1884 return __cfqq; 1885 1886 if (blk_rq_pos(__cfqq->next_rq) < sector) 1887 node = rb_next(&__cfqq->p_node); 1888 else 1889 node = rb_prev(&__cfqq->p_node); 1890 if (!node) 1891 return NULL; 1892 1893 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1894 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1895 return __cfqq; 1896 1897 return NULL; 1898} 1899 1900/* 1901 * cfqd - obvious 1902 * cur_cfqq - passed in so that we don't decide that the current queue is 1903 * closely cooperating with itself. 1904 * 1905 * So, basically we're assuming that that cur_cfqq has dispatched at least 1906 * one request, and that cfqd->last_position reflects a position on the disk 1907 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1908 * assumption. 1909 */ 1910static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1911 struct cfq_queue *cur_cfqq) 1912{ 1913 struct cfq_queue *cfqq; 1914 1915 if (cfq_class_idle(cur_cfqq)) 1916 return NULL; 1917 if (!cfq_cfqq_sync(cur_cfqq)) 1918 return NULL; 1919 if (CFQQ_SEEKY(cur_cfqq)) 1920 return NULL; 1921 1922 /* 1923 * Don't search priority tree if it's the only queue in the group. 1924 */ 1925 if (cur_cfqq->cfqg->nr_cfqq == 1) 1926 return NULL; 1927 1928 /* 1929 * We should notice if some of the queues are cooperating, eg 1930 * working closely on the same area of the disk. In that case, 1931 * we can group them together and don't waste time idling. 1932 */ 1933 cfqq = cfqq_close(cfqd, cur_cfqq); 1934 if (!cfqq) 1935 return NULL; 1936 1937 /* If new queue belongs to different cfq_group, don't choose it */ 1938 if (cur_cfqq->cfqg != cfqq->cfqg) 1939 return NULL; 1940 1941 /* 1942 * It only makes sense to merge sync queues. 1943 */ 1944 if (!cfq_cfqq_sync(cfqq)) 1945 return NULL; 1946 if (CFQQ_SEEKY(cfqq)) 1947 return NULL; 1948 1949 /* 1950 * Do not merge queues of different priority classes 1951 */ 1952 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1953 return NULL; 1954 1955 return cfqq; 1956} 1957 1958/* 1959 * Determine whether we should enforce idle window for this queue. 1960 */ 1961 1962static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1963{ 1964 enum wl_prio_t prio = cfqq_prio(cfqq); 1965 struct cfq_rb_root *service_tree = cfqq->service_tree; 1966 1967 BUG_ON(!service_tree); 1968 BUG_ON(!service_tree->count); 1969 1970 if (!cfqd->cfq_slice_idle) 1971 return false; 1972 1973 /* We never do for idle class queues. */ 1974 if (prio == IDLE_WORKLOAD) 1975 return false; 1976 1977 /* We do for queues that were marked with idle window flag. */ 1978 if (cfq_cfqq_idle_window(cfqq) && 1979 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 1980 return true; 1981 1982 /* 1983 * Otherwise, we do only if they are the last ones 1984 * in their service tree. 1985 */ 1986 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) && 1987 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false)) 1988 return true; 1989 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 1990 service_tree->count); 1991 return false; 1992} 1993 1994static void cfq_arm_slice_timer(struct cfq_data *cfqd) 1995{ 1996 struct cfq_queue *cfqq = cfqd->active_queue; 1997 struct cfq_io_context *cic; 1998 unsigned long sl, group_idle = 0; 1999 2000 /* 2001 * SSD device without seek penalty, disable idling. But only do so 2002 * for devices that support queuing, otherwise we still have a problem 2003 * with sync vs async workloads. 2004 */ 2005 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 2006 return; 2007 2008 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 2009 WARN_ON(cfq_cfqq_slice_new(cfqq)); 2010 2011 /* 2012 * idle is disabled, either manually or by past process history 2013 */ 2014 if (!cfq_should_idle(cfqd, cfqq)) { 2015 /* no queue idling. Check for group idling */ 2016 if (cfqd->cfq_group_idle) 2017 group_idle = cfqd->cfq_group_idle; 2018 else 2019 return; 2020 } 2021 2022 /* 2023 * still active requests from this queue, don't idle 2024 */ 2025 if (cfqq->dispatched) 2026 return; 2027 2028 /* 2029 * task has exited, don't wait 2030 */ 2031 cic = cfqd->active_cic; 2032 if (!cic || !atomic_read(&cic->ioc->nr_tasks)) 2033 return; 2034 2035 /* 2036 * If our average think time is larger than the remaining time 2037 * slice, then don't idle. This avoids overrunning the allotted 2038 * time slice. 2039 */ 2040 if (sample_valid(cic->ttime.ttime_samples) && 2041 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { 2042 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2043 cic->ttime.ttime_mean); 2044 return; 2045 } 2046 2047 /* There are other queues in the group, don't do group idle */ 2048 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2049 return; 2050 2051 cfq_mark_cfqq_wait_request(cfqq); 2052 2053 if (group_idle) 2054 sl = cfqd->cfq_group_idle; 2055 else 2056 sl = cfqd->cfq_slice_idle; 2057 2058 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2059 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); 2060 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2061 group_idle ? 1 : 0); 2062} 2063 2064/* 2065 * Move request from internal lists to the request queue dispatch list. 2066 */ 2067static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2068{ 2069 struct cfq_data *cfqd = q->elevator->elevator_data; 2070 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2071 2072 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2073 2074 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2075 cfq_remove_request(rq); 2076 cfqq->dispatched++; 2077 (RQ_CFQG(rq))->dispatched++; 2078 elv_dispatch_sort(q, rq); 2079 2080 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2081 cfqq->nr_sectors += blk_rq_sectors(rq); 2082 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), 2083 rq_data_dir(rq), rq_is_sync(rq)); 2084} 2085 2086/* 2087 * return expired entry, or NULL to just start from scratch in rbtree 2088 */ 2089static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2090{ 2091 struct request *rq = NULL; 2092 2093 if (cfq_cfqq_fifo_expire(cfqq)) 2094 return NULL; 2095 2096 cfq_mark_cfqq_fifo_expire(cfqq); 2097 2098 if (list_empty(&cfqq->fifo)) 2099 return NULL; 2100 2101 rq = rq_entry_fifo(cfqq->fifo.next); 2102 if (time_before(jiffies, rq_fifo_time(rq))) 2103 rq = NULL; 2104 2105 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2106 return rq; 2107} 2108 2109static inline int 2110cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2111{ 2112 const int base_rq = cfqd->cfq_slice_async_rq; 2113 2114 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2115 2116 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2117} 2118 2119/* 2120 * Must be called with the queue_lock held. 2121 */ 2122static int cfqq_process_refs(struct cfq_queue *cfqq) 2123{ 2124 int process_refs, io_refs; 2125 2126 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2127 process_refs = cfqq->ref - io_refs; 2128 BUG_ON(process_refs < 0); 2129 return process_refs; 2130} 2131 2132static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2133{ 2134 int process_refs, new_process_refs; 2135 struct cfq_queue *__cfqq; 2136 2137 /* 2138 * If there are no process references on the new_cfqq, then it is 2139 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2140 * chain may have dropped their last reference (not just their 2141 * last process reference). 2142 */ 2143 if (!cfqq_process_refs(new_cfqq)) 2144 return; 2145 2146 /* Avoid a circular list and skip interim queue merges */ 2147 while ((__cfqq = new_cfqq->new_cfqq)) { 2148 if (__cfqq == cfqq) 2149 return; 2150 new_cfqq = __cfqq; 2151 } 2152 2153 process_refs = cfqq_process_refs(cfqq); 2154 new_process_refs = cfqq_process_refs(new_cfqq); 2155 /* 2156 * If the process for the cfqq has gone away, there is no 2157 * sense in merging the queues. 2158 */ 2159 if (process_refs == 0 || new_process_refs == 0) 2160 return; 2161 2162 /* 2163 * Merge in the direction of the lesser amount of work. 2164 */ 2165 if (new_process_refs >= process_refs) { 2166 cfqq->new_cfqq = new_cfqq; 2167 new_cfqq->ref += process_refs; 2168 } else { 2169 new_cfqq->new_cfqq = cfqq; 2170 cfqq->ref += new_process_refs; 2171 } 2172} 2173 2174static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 2175 struct cfq_group *cfqg, enum wl_prio_t prio) 2176{ 2177 struct cfq_queue *queue; 2178 int i; 2179 bool key_valid = false; 2180 unsigned long lowest_key = 0; 2181 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2182 2183 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2184 /* select the one with lowest rb_key */ 2185 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2186 if (queue && 2187 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2188 lowest_key = queue->rb_key; 2189 cur_best = i; 2190 key_valid = true; 2191 } 2192 } 2193 2194 return cur_best; 2195} 2196 2197static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2198{ 2199 unsigned slice; 2200 unsigned count; 2201 struct cfq_rb_root *st; 2202 unsigned group_slice; 2203 enum wl_prio_t original_prio = cfqd->serving_prio; 2204 2205 /* Choose next priority. RT > BE > IDLE */ 2206 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2207 cfqd->serving_prio = RT_WORKLOAD; 2208 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2209 cfqd->serving_prio = BE_WORKLOAD; 2210 else { 2211 cfqd->serving_prio = IDLE_WORKLOAD; 2212 cfqd->workload_expires = jiffies + 1; 2213 return; 2214 } 2215 2216 if (original_prio != cfqd->serving_prio) 2217 goto new_workload; 2218 2219 /* 2220 * For RT and BE, we have to choose also the type 2221 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2222 * expiration time 2223 */ 2224 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2225 count = st->count; 2226 2227 /* 2228 * check workload expiration, and that we still have other queues ready 2229 */ 2230 if (count && !time_after(jiffies, cfqd->workload_expires)) 2231 return; 2232 2233new_workload: 2234 /* otherwise select new workload type */ 2235 cfqd->serving_type = 2236 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2237 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2238 count = st->count; 2239 2240 /* 2241 * the workload slice is computed as a fraction of target latency 2242 * proportional to the number of queues in that workload, over 2243 * all the queues in the same priority class 2244 */ 2245 group_slice = cfq_group_slice(cfqd, cfqg); 2246 2247 slice = group_slice * count / 2248 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2249 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2250 2251 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2252 unsigned int tmp; 2253 2254 /* 2255 * Async queues are currently system wide. Just taking 2256 * proportion of queues with-in same group will lead to higher 2257 * async ratio system wide as generally root group is going 2258 * to have higher weight. A more accurate thing would be to 2259 * calculate system wide asnc/sync ratio. 2260 */ 2261 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2262 tmp = tmp/cfqd->busy_queues; 2263 slice = min_t(unsigned, slice, tmp); 2264 2265 /* async workload slice is scaled down according to 2266 * the sync/async slice ratio. */ 2267 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2268 } else 2269 /* sync workload slice is at least 2 * cfq_slice_idle */ 2270 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2271 2272 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2273 cfq_log(cfqd, "workload slice:%d", slice); 2274 cfqd->workload_expires = jiffies + slice; 2275} 2276 2277static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2278{ 2279 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2280 struct cfq_group *cfqg; 2281 2282 if (RB_EMPTY_ROOT(&st->rb)) 2283 return NULL; 2284 cfqg = cfq_rb_first_group(st); 2285 update_min_vdisktime(st); 2286 return cfqg; 2287} 2288 2289static void cfq_choose_cfqg(struct cfq_data *cfqd) 2290{ 2291 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2292 2293 cfqd->serving_group = cfqg; 2294 2295 /* Restore the workload type data */ 2296 if (cfqg->saved_workload_slice) { 2297 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2298 cfqd->serving_type = cfqg->saved_workload; 2299 cfqd->serving_prio = cfqg->saved_serving_prio; 2300 } else 2301 cfqd->workload_expires = jiffies - 1; 2302 2303 choose_service_tree(cfqd, cfqg); 2304} 2305 2306/* 2307 * Select a queue for service. If we have a current active queue, 2308 * check whether to continue servicing it, or retrieve and set a new one. 2309 */ 2310static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2311{ 2312 struct cfq_queue *cfqq, *new_cfqq = NULL; 2313 2314 cfqq = cfqd->active_queue; 2315 if (!cfqq) 2316 goto new_queue; 2317 2318 if (!cfqd->rq_queued) 2319 return NULL; 2320 2321 /* 2322 * We were waiting for group to get backlogged. Expire the queue 2323 */ 2324 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2325 goto expire; 2326 2327 /* 2328 * The active queue has run out of time, expire it and select new. 2329 */ 2330 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2331 /* 2332 * If slice had not expired at the completion of last request 2333 * we might not have turned on wait_busy flag. Don't expire 2334 * the queue yet. Allow the group to get backlogged. 2335 * 2336 * The very fact that we have used the slice, that means we 2337 * have been idling all along on this queue and it should be 2338 * ok to wait for this request to complete. 2339 */ 2340 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2341 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2342 cfqq = NULL; 2343 goto keep_queue; 2344 } else 2345 goto check_group_idle; 2346 } 2347 2348 /* 2349 * The active queue has requests and isn't expired, allow it to 2350 * dispatch. 2351 */ 2352 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2353 goto keep_queue; 2354 2355 /* 2356 * If another queue has a request waiting within our mean seek 2357 * distance, let it run. The expire code will check for close 2358 * cooperators and put the close queue at the front of the service 2359 * tree. If possible, merge the expiring queue with the new cfqq. 2360 */ 2361 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2362 if (new_cfqq) { 2363 if (!cfqq->new_cfqq) 2364 cfq_setup_merge(cfqq, new_cfqq); 2365 goto expire; 2366 } 2367 2368 /* 2369 * No requests pending. If the active queue still has requests in 2370 * flight or is idling for a new request, allow either of these 2371 * conditions to happen (or time out) before selecting a new queue. 2372 */ 2373 if (timer_pending(&cfqd->idle_slice_timer)) { 2374 cfqq = NULL; 2375 goto keep_queue; 2376 } 2377 2378 /* 2379 * This is a deep seek queue, but the device is much faster than 2380 * the queue can deliver, don't idle 2381 **/ 2382 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2383 (cfq_cfqq_slice_new(cfqq) || 2384 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2385 cfq_clear_cfqq_deep(cfqq); 2386 cfq_clear_cfqq_idle_window(cfqq); 2387 } 2388 2389 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2390 cfqq = NULL; 2391 goto keep_queue; 2392 } 2393 2394 /* 2395 * If group idle is enabled and there are requests dispatched from 2396 * this group, wait for requests to complete. 2397 */ 2398check_group_idle: 2399 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && 2400 cfqq->cfqg->dispatched && 2401 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { 2402 cfqq = NULL; 2403 goto keep_queue; 2404 } 2405 2406expire: 2407 cfq_slice_expired(cfqd, 0); 2408new_queue: 2409 /* 2410 * Current queue expired. Check if we have to switch to a new 2411 * service tree 2412 */ 2413 if (!new_cfqq) 2414 cfq_choose_cfqg(cfqd); 2415 2416 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2417keep_queue: 2418 return cfqq; 2419} 2420 2421static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2422{ 2423 int dispatched = 0; 2424 2425 while (cfqq->next_rq) { 2426 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2427 dispatched++; 2428 } 2429 2430 BUG_ON(!list_empty(&cfqq->fifo)); 2431 2432 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2433 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2434 return dispatched; 2435} 2436 2437/* 2438 * Drain our current requests. Used for barriers and when switching 2439 * io schedulers on-the-fly. 2440 */ 2441static int cfq_forced_dispatch(struct cfq_data *cfqd) 2442{ 2443 struct cfq_queue *cfqq; 2444 int dispatched = 0; 2445 2446 /* Expire the timeslice of the current active queue first */ 2447 cfq_slice_expired(cfqd, 0); 2448 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2449 __cfq_set_active_queue(cfqd, cfqq); 2450 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2451 } 2452 2453 BUG_ON(cfqd->busy_queues); 2454 2455 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2456 return dispatched; 2457} 2458 2459static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2460 struct cfq_queue *cfqq) 2461{ 2462 /* the queue hasn't finished any request, can't estimate */ 2463 if (cfq_cfqq_slice_new(cfqq)) 2464 return true; 2465 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2466 cfqq->slice_end)) 2467 return true; 2468 2469 return false; 2470} 2471 2472static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2473{ 2474 unsigned int max_dispatch; 2475 2476 /* 2477 * Drain async requests before we start sync IO 2478 */ 2479 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2480 return false; 2481 2482 /* 2483 * If this is an async queue and we have sync IO in flight, let it wait 2484 */ 2485 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2486 return false; 2487 2488 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2489 if (cfq_class_idle(cfqq)) 2490 max_dispatch = 1; 2491 2492 /* 2493 * Does this cfqq already have too much IO in flight? 2494 */ 2495 if (cfqq->dispatched >= max_dispatch) { 2496 bool promote_sync = false; 2497 /* 2498 * idle queue must always only have a single IO in flight 2499 */ 2500 if (cfq_class_idle(cfqq)) 2501 return false; 2502 2503 /* 2504 * If there is only one sync queue 2505 * we can ignore async queue here and give the sync 2506 * queue no dispatch limit. The reason is a sync queue can 2507 * preempt async queue, limiting the sync queue doesn't make 2508 * sense. This is useful for aiostress test. 2509 */ 2510 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2511 promote_sync = true; 2512 2513 /* 2514 * We have other queues, don't allow more IO from this one 2515 */ 2516 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2517 !promote_sync) 2518 return false; 2519 2520 /* 2521 * Sole queue user, no limit 2522 */ 2523 if (cfqd->busy_queues == 1 || promote_sync) 2524 max_dispatch = -1; 2525 else 2526 /* 2527 * Normally we start throttling cfqq when cfq_quantum/2 2528 * requests have been dispatched. But we can drive 2529 * deeper queue depths at the beginning of slice 2530 * subjected to upper limit of cfq_quantum. 2531 * */ 2532 max_dispatch = cfqd->cfq_quantum; 2533 } 2534 2535 /* 2536 * Async queues must wait a bit before being allowed dispatch. 2537 * We also ramp up the dispatch depth gradually for async IO, 2538 * based on the last sync IO we serviced 2539 */ 2540 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2541 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2542 unsigned int depth; 2543 2544 depth = last_sync / cfqd->cfq_slice[1]; 2545 if (!depth && !cfqq->dispatched) 2546 depth = 1; 2547 if (depth < max_dispatch) 2548 max_dispatch = depth; 2549 } 2550 2551 /* 2552 * If we're below the current max, allow a dispatch 2553 */ 2554 return cfqq->dispatched < max_dispatch; 2555} 2556 2557/* 2558 * Dispatch a request from cfqq, moving them to the request queue 2559 * dispatch list. 2560 */ 2561static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2562{ 2563 struct request *rq; 2564 2565 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2566 2567 if (!cfq_may_dispatch(cfqd, cfqq)) 2568 return false; 2569 2570 /* 2571 * follow expired path, else get first next available 2572 */ 2573 rq = cfq_check_fifo(cfqq); 2574 if (!rq) 2575 rq = cfqq->next_rq; 2576 2577 /* 2578 * insert request into driver dispatch list 2579 */ 2580 cfq_dispatch_insert(cfqd->queue, rq); 2581 2582 if (!cfqd->active_cic) { 2583 struct cfq_io_context *cic = RQ_CIC(rq); 2584 2585 atomic_long_inc(&cic->ioc->refcount); 2586 cfqd->active_cic = cic; 2587 } 2588 2589 return true; 2590} 2591 2592/* 2593 * Find the cfqq that we need to service and move a request from that to the 2594 * dispatch list 2595 */ 2596static int cfq_dispatch_requests(struct request_queue *q, int force) 2597{ 2598 struct cfq_data *cfqd = q->elevator->elevator_data; 2599 struct cfq_queue *cfqq; 2600 2601 if (!cfqd->busy_queues) 2602 return 0; 2603 2604 if (unlikely(force)) 2605 return cfq_forced_dispatch(cfqd); 2606 2607 cfqq = cfq_select_queue(cfqd); 2608 if (!cfqq) 2609 return 0; 2610 2611 /* 2612 * Dispatch a request from this cfqq, if it is allowed 2613 */ 2614 if (!cfq_dispatch_request(cfqd, cfqq)) 2615 return 0; 2616 2617 cfqq->slice_dispatch++; 2618 cfq_clear_cfqq_must_dispatch(cfqq); 2619 2620 /* 2621 * expire an async queue immediately if it has used up its slice. idle 2622 * queue always expire after 1 dispatch round. 2623 */ 2624 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2625 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2626 cfq_class_idle(cfqq))) { 2627 cfqq->slice_end = jiffies + 1; 2628 cfq_slice_expired(cfqd, 0); 2629 } 2630 2631 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2632 return 1; 2633} 2634 2635/* 2636 * task holds one reference to the queue, dropped when task exits. each rq 2637 * in-flight on this queue also holds a reference, dropped when rq is freed. 2638 * 2639 * Each cfq queue took a reference on the parent group. Drop it now. 2640 * queue lock must be held here. 2641 */ 2642static void cfq_put_queue(struct cfq_queue *cfqq) 2643{ 2644 struct cfq_data *cfqd = cfqq->cfqd; 2645 struct cfq_group *cfqg; 2646 2647 BUG_ON(cfqq->ref <= 0); 2648 2649 cfqq->ref--; 2650 if (cfqq->ref) 2651 return; 2652 2653 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2654 BUG_ON(rb_first(&cfqq->sort_list)); 2655 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2656 cfqg = cfqq->cfqg; 2657 2658 if (unlikely(cfqd->active_queue == cfqq)) { 2659 __cfq_slice_expired(cfqd, cfqq, 0); 2660 cfq_schedule_dispatch(cfqd); 2661 } 2662 2663 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2664 kmem_cache_free(cfq_pool, cfqq); 2665 cfq_put_cfqg(cfqg); 2666} 2667 2668/* 2669 * Call func for each cic attached to this ioc. 2670 */ 2671static void 2672call_for_each_cic(struct io_context *ioc, 2673 void (*func)(struct io_context *, struct cfq_io_context *)) 2674{ 2675 struct cfq_io_context *cic; 2676 struct hlist_node *n; 2677 2678 rcu_read_lock(); 2679 2680 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) 2681 func(ioc, cic); 2682 2683 rcu_read_unlock(); 2684} 2685 2686static void cfq_cic_free_rcu(struct rcu_head *head) 2687{ 2688 struct cfq_io_context *cic; 2689 2690 cic = container_of(head, struct cfq_io_context, rcu_head); 2691 2692 kmem_cache_free(cfq_ioc_pool, cic); 2693 elv_ioc_count_dec(cfq_ioc_count); 2694 2695 if (ioc_gone) { 2696 /* 2697 * CFQ scheduler is exiting, grab exit lock and check 2698 * the pending io context count. If it hits zero, 2699 * complete ioc_gone and set it back to NULL 2700 */ 2701 spin_lock(&ioc_gone_lock); 2702 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { 2703 complete(ioc_gone); 2704 ioc_gone = NULL; 2705 } 2706 spin_unlock(&ioc_gone_lock); 2707 } 2708} 2709 2710static void cfq_cic_free(struct cfq_io_context *cic) 2711{ 2712 call_rcu(&cic->rcu_head, cfq_cic_free_rcu); 2713} 2714 2715static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) 2716{ 2717 unsigned long flags; 2718 unsigned long dead_key = (unsigned long) cic->key; 2719 2720 BUG_ON(!(dead_key & CIC_DEAD_KEY)); 2721 2722 spin_lock_irqsave(&ioc->lock, flags); 2723 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); 2724 hlist_del_rcu(&cic->cic_list); 2725 spin_unlock_irqrestore(&ioc->lock, flags); 2726 2727 cfq_cic_free(cic); 2728} 2729 2730/* 2731 * Must be called with rcu_read_lock() held or preemption otherwise disabled. 2732 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), 2733 * and ->trim() which is called with the task lock held 2734 */ 2735static void cfq_free_io_context(struct io_context *ioc) 2736{ 2737 /* 2738 * ioc->refcount is zero here, or we are called from elv_unregister(), 2739 * so no more cic's are allowed to be linked into this ioc. So it 2740 * should be ok to iterate over the known list, we will see all cic's 2741 * since no new ones are added. 2742 */ 2743 call_for_each_cic(ioc, cic_free_func); 2744} 2745 2746static void cfq_put_cooperator(struct cfq_queue *cfqq) 2747{ 2748 struct cfq_queue *__cfqq, *next; 2749 2750 /* 2751 * If this queue was scheduled to merge with another queue, be 2752 * sure to drop the reference taken on that queue (and others in 2753 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2754 */ 2755 __cfqq = cfqq->new_cfqq; 2756 while (__cfqq) { 2757 if (__cfqq == cfqq) { 2758 WARN(1, "cfqq->new_cfqq loop detected\n"); 2759 break; 2760 } 2761 next = __cfqq->new_cfqq; 2762 cfq_put_queue(__cfqq); 2763 __cfqq = next; 2764 } 2765} 2766 2767static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2768{ 2769 if (unlikely(cfqq == cfqd->active_queue)) { 2770 __cfq_slice_expired(cfqd, cfqq, 0); 2771 cfq_schedule_dispatch(cfqd); 2772 } 2773 2774 cfq_put_cooperator(cfqq); 2775 2776 cfq_put_queue(cfqq); 2777} 2778 2779static void __cfq_exit_single_io_context(struct cfq_data *cfqd, 2780 struct cfq_io_context *cic) 2781{ 2782 struct io_context *ioc = cic->ioc; 2783 2784 list_del_init(&cic->queue_list); 2785 2786 /* 2787 * Make sure dead mark is seen for dead queues 2788 */ 2789 smp_wmb(); 2790 cic->key = cfqd_dead_key(cfqd); 2791 2792 rcu_read_lock(); 2793 if (rcu_dereference(ioc->ioc_data) == cic) { 2794 rcu_read_unlock(); 2795 spin_lock(&ioc->lock); 2796 rcu_assign_pointer(ioc->ioc_data, NULL); 2797 spin_unlock(&ioc->lock); 2798 } else 2799 rcu_read_unlock(); 2800 2801 if (cic->cfqq[BLK_RW_ASYNC]) { 2802 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2803 cic->cfqq[BLK_RW_ASYNC] = NULL; 2804 } 2805 2806 if (cic->cfqq[BLK_RW_SYNC]) { 2807 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2808 cic->cfqq[BLK_RW_SYNC] = NULL; 2809 } 2810} 2811 2812static void cfq_exit_single_io_context(struct io_context *ioc, 2813 struct cfq_io_context *cic) 2814{ 2815 struct cfq_data *cfqd = cic_to_cfqd(cic); 2816 2817 if (cfqd) { 2818 struct request_queue *q = cfqd->queue; 2819 unsigned long flags; 2820 2821 spin_lock_irqsave(q->queue_lock, flags); 2822 2823 /* 2824 * Ensure we get a fresh copy of the ->key to prevent 2825 * race between exiting task and queue 2826 */ 2827 smp_read_barrier_depends(); 2828 if (cic->key == cfqd) 2829 __cfq_exit_single_io_context(cfqd, cic); 2830 2831 spin_unlock_irqrestore(q->queue_lock, flags); 2832 } 2833} 2834 2835/* 2836 * The process that ioc belongs to has exited, we need to clean up 2837 * and put the internal structures we have that belongs to that process. 2838 */ 2839static void cfq_exit_io_context(struct io_context *ioc) 2840{ 2841 call_for_each_cic(ioc, cfq_exit_single_io_context); 2842} 2843 2844static struct cfq_io_context * 2845cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2846{ 2847 struct cfq_io_context *cic; 2848 2849 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, 2850 cfqd->queue->node); 2851 if (cic) { 2852 cic->ttime.last_end_request = jiffies; 2853 INIT_LIST_HEAD(&cic->queue_list); 2854 INIT_HLIST_NODE(&cic->cic_list); 2855 cic->dtor = cfq_free_io_context; 2856 cic->exit = cfq_exit_io_context; 2857 elv_ioc_count_inc(cfq_ioc_count); 2858 } 2859 2860 return cic; 2861} 2862 2863static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2864{ 2865 struct task_struct *tsk = current; 2866 int ioprio_class; 2867 2868 if (!cfq_cfqq_prio_changed(cfqq)) 2869 return; 2870 2871 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2872 switch (ioprio_class) { 2873 default: 2874 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2875 case IOPRIO_CLASS_NONE: 2876 /* 2877 * no prio set, inherit CPU scheduling settings 2878 */ 2879 cfqq->ioprio = task_nice_ioprio(tsk); 2880 cfqq->ioprio_class = task_nice_ioclass(tsk); 2881 break; 2882 case IOPRIO_CLASS_RT: 2883 cfqq->ioprio = task_ioprio(ioc); 2884 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2885 break; 2886 case IOPRIO_CLASS_BE: 2887 cfqq->ioprio = task_ioprio(ioc); 2888 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2889 break; 2890 case IOPRIO_CLASS_IDLE: 2891 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2892 cfqq->ioprio = 7; 2893 cfq_clear_cfqq_idle_window(cfqq); 2894 break; 2895 } 2896 2897 /* 2898 * keep track of original prio settings in case we have to temporarily 2899 * elevate the priority of this queue 2900 */ 2901 cfqq->org_ioprio = cfqq->ioprio; 2902 cfq_clear_cfqq_prio_changed(cfqq); 2903} 2904 2905static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) 2906{ 2907 struct cfq_data *cfqd = cic_to_cfqd(cic); 2908 struct cfq_queue *cfqq; 2909 unsigned long flags; 2910 2911 if (unlikely(!cfqd)) 2912 return; 2913 2914 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2915 2916 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2917 if (cfqq) { 2918 struct cfq_queue *new_cfqq; 2919 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, 2920 GFP_ATOMIC); 2921 if (new_cfqq) { 2922 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2923 cfq_put_queue(cfqq); 2924 } 2925 } 2926 2927 cfqq = cic->cfqq[BLK_RW_SYNC]; 2928 if (cfqq) 2929 cfq_mark_cfqq_prio_changed(cfqq); 2930 2931 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2932} 2933 2934static void cfq_ioc_set_ioprio(struct io_context *ioc) 2935{ 2936 call_for_each_cic(ioc, changed_ioprio); 2937 ioc->ioprio_changed = 0; 2938} 2939 2940static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2941 pid_t pid, bool is_sync) 2942{ 2943 RB_CLEAR_NODE(&cfqq->rb_node); 2944 RB_CLEAR_NODE(&cfqq->p_node); 2945 INIT_LIST_HEAD(&cfqq->fifo); 2946 2947 cfqq->ref = 0; 2948 cfqq->cfqd = cfqd; 2949 2950 cfq_mark_cfqq_prio_changed(cfqq); 2951 2952 if (is_sync) { 2953 if (!cfq_class_idle(cfqq)) 2954 cfq_mark_cfqq_idle_window(cfqq); 2955 cfq_mark_cfqq_sync(cfqq); 2956 } 2957 cfqq->pid = pid; 2958} 2959 2960#ifdef CONFIG_CFQ_GROUP_IOSCHED 2961static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) 2962{ 2963 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2964 struct cfq_data *cfqd = cic_to_cfqd(cic); 2965 unsigned long flags; 2966 struct request_queue *q; 2967 2968 if (unlikely(!cfqd)) 2969 return; 2970 2971 q = cfqd->queue; 2972 2973 spin_lock_irqsave(q->queue_lock, flags); 2974 2975 if (sync_cfqq) { 2976 /* 2977 * Drop reference to sync queue. A new sync queue will be 2978 * assigned in new group upon arrival of a fresh request. 2979 */ 2980 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2981 cic_set_cfqq(cic, NULL, 1); 2982 cfq_put_queue(sync_cfqq); 2983 } 2984 2985 spin_unlock_irqrestore(q->queue_lock, flags); 2986} 2987 2988static void cfq_ioc_set_cgroup(struct io_context *ioc) 2989{ 2990 call_for_each_cic(ioc, changed_cgroup); 2991 ioc->cgroup_changed = 0; 2992} 2993#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2994 2995static struct cfq_queue * 2996cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2997 struct io_context *ioc, gfp_t gfp_mask) 2998{ 2999 struct cfq_queue *cfqq, *new_cfqq = NULL; 3000 struct cfq_io_context *cic; 3001 struct cfq_group *cfqg; 3002 3003retry: 3004 cfqg = cfq_get_cfqg(cfqd); 3005 cic = cfq_cic_lookup(cfqd, ioc); 3006 /* cic always exists here */ 3007 cfqq = cic_to_cfqq(cic, is_sync); 3008 3009 /* 3010 * Always try a new alloc if we fell back to the OOM cfqq 3011 * originally, since it should just be a temporary situation. 3012 */ 3013 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3014 cfqq = NULL; 3015 if (new_cfqq) { 3016 cfqq = new_cfqq; 3017 new_cfqq = NULL; 3018 } else if (gfp_mask & __GFP_WAIT) { 3019 spin_unlock_irq(cfqd->queue->queue_lock); 3020 new_cfqq = kmem_cache_alloc_node(cfq_pool, 3021 gfp_mask | __GFP_ZERO, 3022 cfqd->queue->node); 3023 spin_lock_irq(cfqd->queue->queue_lock); 3024 if (new_cfqq) 3025 goto retry; 3026 } else { 3027 cfqq = kmem_cache_alloc_node(cfq_pool, 3028 gfp_mask | __GFP_ZERO, 3029 cfqd->queue->node); 3030 } 3031 3032 if (cfqq) { 3033 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3034 cfq_init_prio_data(cfqq, ioc); 3035 cfq_link_cfqq_cfqg(cfqq, cfqg); 3036 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3037 } else 3038 cfqq = &cfqd->oom_cfqq; 3039 } 3040 3041 if (new_cfqq) 3042 kmem_cache_free(cfq_pool, new_cfqq); 3043 3044 return cfqq; 3045} 3046 3047static struct cfq_queue ** 3048cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3049{ 3050 switch (ioprio_class) { 3051 case IOPRIO_CLASS_RT: 3052 return &cfqd->async_cfqq[0][ioprio]; 3053 case IOPRIO_CLASS_BE: 3054 return &cfqd->async_cfqq[1][ioprio]; 3055 case IOPRIO_CLASS_IDLE: 3056 return &cfqd->async_idle_cfqq; 3057 default: 3058 BUG(); 3059 } 3060} 3061 3062static struct cfq_queue * 3063cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 3064 gfp_t gfp_mask) 3065{ 3066 const int ioprio = task_ioprio(ioc); 3067 const int ioprio_class = task_ioprio_class(ioc); 3068 struct cfq_queue **async_cfqq = NULL; 3069 struct cfq_queue *cfqq = NULL; 3070 3071 if (!is_sync) { 3072 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3073 cfqq = *async_cfqq; 3074 } 3075 3076 if (!cfqq) 3077 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 3078 3079 /* 3080 * pin the queue now that it's allocated, scheduler exit will prune it 3081 */ 3082 if (!is_sync && !(*async_cfqq)) { 3083 cfqq->ref++; 3084 *async_cfqq = cfqq; 3085 } 3086 3087 cfqq->ref++; 3088 return cfqq; 3089} 3090 3091/* 3092 * We drop cfq io contexts lazily, so we may find a dead one. 3093 */ 3094static void 3095cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, 3096 struct cfq_io_context *cic) 3097{ 3098 unsigned long flags; 3099 3100 WARN_ON(!list_empty(&cic->queue_list)); 3101 BUG_ON(cic->key != cfqd_dead_key(cfqd)); 3102 3103 spin_lock_irqsave(&ioc->lock, flags); 3104 3105 BUG_ON(rcu_dereference_check(ioc->ioc_data, 3106 lockdep_is_held(&ioc->lock)) == cic); 3107 3108 radix_tree_delete(&ioc->radix_root, cfqd->cic_index); 3109 hlist_del_rcu(&cic->cic_list); 3110 spin_unlock_irqrestore(&ioc->lock, flags); 3111 3112 cfq_cic_free(cic); 3113} 3114 3115static struct cfq_io_context * 3116cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) 3117{ 3118 struct cfq_io_context *cic; 3119 unsigned long flags; 3120 3121 if (unlikely(!ioc)) 3122 return NULL; 3123 3124 rcu_read_lock(); 3125 3126 /* 3127 * we maintain a last-hit cache, to avoid browsing over the tree 3128 */ 3129 cic = rcu_dereference(ioc->ioc_data); 3130 if (cic && cic->key == cfqd) { 3131 rcu_read_unlock(); 3132 return cic; 3133 } 3134 3135 do { 3136 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); 3137 rcu_read_unlock(); 3138 if (!cic) 3139 break; 3140 if (unlikely(cic->key != cfqd)) { 3141 cfq_drop_dead_cic(cfqd, ioc, cic); 3142 rcu_read_lock(); 3143 continue; 3144 } 3145 3146 spin_lock_irqsave(&ioc->lock, flags); 3147 rcu_assign_pointer(ioc->ioc_data, cic); 3148 spin_unlock_irqrestore(&ioc->lock, flags); 3149 break; 3150 } while (1); 3151 3152 return cic; 3153} 3154 3155/* 3156 * Add cic into ioc, using cfqd as the search key. This enables us to lookup 3157 * the process specific cfq io context when entered from the block layer. 3158 * Also adds the cic to a per-cfqd list, used when this queue is removed. 3159 */ 3160static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, 3161 struct cfq_io_context *cic, gfp_t gfp_mask) 3162{ 3163 unsigned long flags; 3164 int ret; 3165 3166 ret = radix_tree_preload(gfp_mask); 3167 if (!ret) { 3168 cic->ioc = ioc; 3169 cic->key = cfqd; 3170 3171 spin_lock_irqsave(&ioc->lock, flags); 3172 ret = radix_tree_insert(&ioc->radix_root, 3173 cfqd->cic_index, cic); 3174 if (!ret) 3175 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); 3176 spin_unlock_irqrestore(&ioc->lock, flags); 3177 3178 radix_tree_preload_end(); 3179 3180 if (!ret) { 3181 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3182 list_add(&cic->queue_list, &cfqd->cic_list); 3183 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3184 } 3185 } 3186 3187 if (ret && ret != -EEXIST) 3188 printk(KERN_ERR "cfq: cic link failed!\n"); 3189 3190 return ret; 3191} 3192 3193/* 3194 * Setup general io context and cfq io context. There can be several cfq 3195 * io contexts per general io context, if this process is doing io to more 3196 * than one device managed by cfq. 3197 */ 3198static struct cfq_io_context * 3199cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 3200{ 3201 struct io_context *ioc = NULL; 3202 struct cfq_io_context *cic; 3203 int ret; 3204 3205 might_sleep_if(gfp_mask & __GFP_WAIT); 3206 3207 ioc = get_io_context(gfp_mask, cfqd->queue->node); 3208 if (!ioc) 3209 return NULL; 3210 3211retry: 3212 cic = cfq_cic_lookup(cfqd, ioc); 3213 if (cic) 3214 goto out; 3215 3216 cic = cfq_alloc_io_context(cfqd, gfp_mask); 3217 if (cic == NULL) 3218 goto err; 3219 3220 ret = cfq_cic_link(cfqd, ioc, cic, gfp_mask); 3221 if (ret == -EEXIST) { 3222 /* someone has linked cic to ioc already */ 3223 cfq_cic_free(cic); 3224 goto retry; 3225 } else if (ret) 3226 goto err_free; 3227 3228out: 3229 smp_read_barrier_depends(); 3230 if (unlikely(ioc->ioprio_changed)) 3231 cfq_ioc_set_ioprio(ioc); 3232 3233#ifdef CONFIG_CFQ_GROUP_IOSCHED 3234 if (unlikely(ioc->cgroup_changed)) 3235 cfq_ioc_set_cgroup(ioc); 3236#endif 3237 return cic; 3238err_free: 3239 cfq_cic_free(cic); 3240err: 3241 put_io_context(ioc); 3242 return NULL; 3243} 3244 3245static void 3246__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) 3247{ 3248 unsigned long elapsed = jiffies - ttime->last_end_request; 3249 elapsed = min(elapsed, 2UL * slice_idle); 3250 3251 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; 3252 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; 3253 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; 3254} 3255 3256static void 3257cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3258 struct cfq_io_context *cic) 3259{ 3260 if (cfq_cfqq_sync(cfqq)) { 3261 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); 3262 __cfq_update_io_thinktime(&cfqq->service_tree->ttime, 3263 cfqd->cfq_slice_idle); 3264 } 3265#ifdef CONFIG_CFQ_GROUP_IOSCHED 3266 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); 3267#endif 3268} 3269 3270static void 3271cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3272 struct request *rq) 3273{ 3274 sector_t sdist = 0; 3275 sector_t n_sec = blk_rq_sectors(rq); 3276 if (cfqq->last_request_pos) { 3277 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3278 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3279 else 3280 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3281 } 3282 3283 cfqq->seek_history <<= 1; 3284 if (blk_queue_nonrot(cfqd->queue)) 3285 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3286 else 3287 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3288} 3289 3290/* 3291 * Disable idle window if the process thinks too long or seeks so much that 3292 * it doesn't matter 3293 */ 3294static void 3295cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3296 struct cfq_io_context *cic) 3297{ 3298 int old_idle, enable_idle; 3299 3300 /* 3301 * Don't idle for async or idle io prio class 3302 */ 3303 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3304 return; 3305 3306 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3307 3308 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3309 cfq_mark_cfqq_deep(cfqq); 3310 3311 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3312 enable_idle = 0; 3313 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || 3314 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3315 enable_idle = 0; 3316 else if (sample_valid(cic->ttime.ttime_samples)) { 3317 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) 3318 enable_idle = 0; 3319 else 3320 enable_idle = 1; 3321 } 3322 3323 if (old_idle != enable_idle) { 3324 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3325 if (enable_idle) 3326 cfq_mark_cfqq_idle_window(cfqq); 3327 else 3328 cfq_clear_cfqq_idle_window(cfqq); 3329 } 3330} 3331 3332/* 3333 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3334 * no or if we aren't sure, a 1 will cause a preempt. 3335 */ 3336static bool 3337cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3338 struct request *rq) 3339{ 3340 struct cfq_queue *cfqq; 3341 3342 cfqq = cfqd->active_queue; 3343 if (!cfqq) 3344 return false; 3345 3346 if (cfq_class_idle(new_cfqq)) 3347 return false; 3348 3349 if (cfq_class_idle(cfqq)) 3350 return true; 3351 3352 /* 3353 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3354 */ 3355 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3356 return false; 3357 3358 /* 3359 * if the new request is sync, but the currently running queue is 3360 * not, let the sync request have priority. 3361 */ 3362 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3363 return true; 3364 3365 if (new_cfqq->cfqg != cfqq->cfqg) 3366 return false; 3367 3368 if (cfq_slice_used(cfqq)) 3369 return true; 3370 3371 /* Allow preemption only if we are idling on sync-noidle tree */ 3372 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3373 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3374 new_cfqq->service_tree->count == 2 && 3375 RB_EMPTY_ROOT(&cfqq->sort_list)) 3376 return true; 3377 3378 /* 3379 * So both queues are sync. Let the new request get disk time if 3380 * it's a metadata request and the current queue is doing regular IO. 3381 */ 3382 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) 3383 return true; 3384 3385 /* 3386 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3387 */ 3388 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3389 return true; 3390 3391 /* An idle queue should not be idle now for some reason */ 3392 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3393 return true; 3394 3395 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3396 return false; 3397 3398 /* 3399 * if this request is as-good as one we would expect from the 3400 * current cfqq, let it preempt 3401 */ 3402 if (cfq_rq_close(cfqd, cfqq, rq)) 3403 return true; 3404 3405 return false; 3406} 3407 3408/* 3409 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3410 * let it have half of its nominal slice. 3411 */ 3412static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3413{ 3414 struct cfq_queue *old_cfqq = cfqd->active_queue; 3415 3416 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3417 cfq_slice_expired(cfqd, 1); 3418 3419 /* 3420 * workload type is changed, don't save slice, otherwise preempt 3421 * doesn't happen 3422 */ 3423 if (cfqq_type(old_cfqq) != cfqq_type(cfqq)) 3424 cfqq->cfqg->saved_workload_slice = 0; 3425 3426 /* 3427 * Put the new queue at the front of the of the current list, 3428 * so we know that it will be selected next. 3429 */ 3430 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3431 3432 cfq_service_tree_add(cfqd, cfqq, 1); 3433 3434 cfqq->slice_end = 0; 3435 cfq_mark_cfqq_slice_new(cfqq); 3436} 3437 3438/* 3439 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3440 * something we should do about it 3441 */ 3442static void 3443cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3444 struct request *rq) 3445{ 3446 struct cfq_io_context *cic = RQ_CIC(rq); 3447 3448 cfqd->rq_queued++; 3449 if (rq->cmd_flags & REQ_PRIO) 3450 cfqq->prio_pending++; 3451 3452 cfq_update_io_thinktime(cfqd, cfqq, cic); 3453 cfq_update_io_seektime(cfqd, cfqq, rq); 3454 cfq_update_idle_window(cfqd, cfqq, cic); 3455 3456 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3457 3458 if (cfqq == cfqd->active_queue) { 3459 /* 3460 * Remember that we saw a request from this process, but 3461 * don't start queuing just yet. Otherwise we risk seeing lots 3462 * of tiny requests, because we disrupt the normal plugging 3463 * and merging. If the request is already larger than a single 3464 * page, let it rip immediately. For that case we assume that 3465 * merging is already done. Ditto for a busy system that 3466 * has other work pending, don't risk delaying until the 3467 * idle timer unplug to continue working. 3468 */ 3469 if (cfq_cfqq_wait_request(cfqq)) { 3470 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3471 cfqd->busy_queues > 1) { 3472 cfq_del_timer(cfqd, cfqq); 3473 cfq_clear_cfqq_wait_request(cfqq); 3474 __blk_run_queue(cfqd->queue); 3475 } else { 3476 cfq_blkiocg_update_idle_time_stats( 3477 &cfqq->cfqg->blkg); 3478 cfq_mark_cfqq_must_dispatch(cfqq); 3479 } 3480 } 3481 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3482 /* 3483 * not the active queue - expire current slice if it is 3484 * idle and has expired it's mean thinktime or this new queue 3485 * has some old slice time left and is of higher priority or 3486 * this new queue is RT and the current one is BE 3487 */ 3488 cfq_preempt_queue(cfqd, cfqq); 3489 __blk_run_queue(cfqd->queue); 3490 } 3491} 3492 3493static void cfq_insert_request(struct request_queue *q, struct request *rq) 3494{ 3495 struct cfq_data *cfqd = q->elevator->elevator_data; 3496 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3497 3498 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3499 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); 3500 3501 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3502 list_add_tail(&rq->queuelist, &cfqq->fifo); 3503 cfq_add_rq_rb(rq); 3504 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 3505 &cfqd->serving_group->blkg, rq_data_dir(rq), 3506 rq_is_sync(rq)); 3507 cfq_rq_enqueued(cfqd, cfqq, rq); 3508} 3509 3510/* 3511 * Update hw_tag based on peak queue depth over 50 samples under 3512 * sufficient load. 3513 */ 3514static void cfq_update_hw_tag(struct cfq_data *cfqd) 3515{ 3516 struct cfq_queue *cfqq = cfqd->active_queue; 3517 3518 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3519 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3520 3521 if (cfqd->hw_tag == 1) 3522 return; 3523 3524 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3525 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3526 return; 3527 3528 /* 3529 * If active queue hasn't enough requests and can idle, cfq might not 3530 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3531 * case 3532 */ 3533 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3534 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3535 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3536 return; 3537 3538 if (cfqd->hw_tag_samples++ < 50) 3539 return; 3540 3541 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3542 cfqd->hw_tag = 1; 3543 else 3544 cfqd->hw_tag = 0; 3545} 3546 3547static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3548{ 3549 struct cfq_io_context *cic = cfqd->active_cic; 3550 3551 /* If the queue already has requests, don't wait */ 3552 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3553 return false; 3554 3555 /* If there are other queues in the group, don't wait */ 3556 if (cfqq->cfqg->nr_cfqq > 1) 3557 return false; 3558 3559 /* the only queue in the group, but think time is big */ 3560 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) 3561 return false; 3562 3563 if (cfq_slice_used(cfqq)) 3564 return true; 3565 3566 /* if slice left is less than think time, wait busy */ 3567 if (cic && sample_valid(cic->ttime.ttime_samples) 3568 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) 3569 return true; 3570 3571 /* 3572 * If think times is less than a jiffy than ttime_mean=0 and above 3573 * will not be true. It might happen that slice has not expired yet 3574 * but will expire soon (4-5 ns) during select_queue(). To cover the 3575 * case where think time is less than a jiffy, mark the queue wait 3576 * busy if only 1 jiffy is left in the slice. 3577 */ 3578 if (cfqq->slice_end - jiffies == 1) 3579 return true; 3580 3581 return false; 3582} 3583 3584static void cfq_completed_request(struct request_queue *q, struct request *rq) 3585{ 3586 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3587 struct cfq_data *cfqd = cfqq->cfqd; 3588 const int sync = rq_is_sync(rq); 3589 unsigned long now; 3590 3591 now = jiffies; 3592 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3593 !!(rq->cmd_flags & REQ_NOIDLE)); 3594 3595 cfq_update_hw_tag(cfqd); 3596 3597 WARN_ON(!cfqd->rq_in_driver); 3598 WARN_ON(!cfqq->dispatched); 3599 cfqd->rq_in_driver--; 3600 cfqq->dispatched--; 3601 (RQ_CFQG(rq))->dispatched--; 3602 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, 3603 rq_start_time_ns(rq), rq_io_start_time_ns(rq), 3604 rq_data_dir(rq), rq_is_sync(rq)); 3605 3606 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3607 3608 if (sync) { 3609 struct cfq_rb_root *service_tree; 3610 3611 RQ_CIC(rq)->ttime.last_end_request = now; 3612 3613 if (cfq_cfqq_on_rr(cfqq)) 3614 service_tree = cfqq->service_tree; 3615 else 3616 service_tree = service_tree_for(cfqq->cfqg, 3617 cfqq_prio(cfqq), cfqq_type(cfqq)); 3618 service_tree->ttime.last_end_request = now; 3619 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3620 cfqd->last_delayed_sync = now; 3621 } 3622 3623#ifdef CONFIG_CFQ_GROUP_IOSCHED 3624 cfqq->cfqg->ttime.last_end_request = now; 3625#endif 3626 3627 /* 3628 * If this is the active queue, check if it needs to be expired, 3629 * or if we want to idle in case it has no pending requests. 3630 */ 3631 if (cfqd->active_queue == cfqq) { 3632 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3633 3634 if (cfq_cfqq_slice_new(cfqq)) { 3635 cfq_set_prio_slice(cfqd, cfqq); 3636 cfq_clear_cfqq_slice_new(cfqq); 3637 } 3638 3639 /* 3640 * Should we wait for next request to come in before we expire 3641 * the queue. 3642 */ 3643 if (cfq_should_wait_busy(cfqd, cfqq)) { 3644 unsigned long extend_sl = cfqd->cfq_slice_idle; 3645 if (!cfqd->cfq_slice_idle) 3646 extend_sl = cfqd->cfq_group_idle; 3647 cfqq->slice_end = jiffies + extend_sl; 3648 cfq_mark_cfqq_wait_busy(cfqq); 3649 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3650 } 3651 3652 /* 3653 * Idling is not enabled on: 3654 * - expired queues 3655 * - idle-priority queues 3656 * - async queues 3657 * - queues with still some requests queued 3658 * - when there is a close cooperator 3659 */ 3660 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3661 cfq_slice_expired(cfqd, 1); 3662 else if (sync && cfqq_empty && 3663 !cfq_close_cooperator(cfqd, cfqq)) { 3664 cfq_arm_slice_timer(cfqd); 3665 } 3666 } 3667 3668 if (!cfqd->rq_in_driver) 3669 cfq_schedule_dispatch(cfqd); 3670} 3671 3672static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3673{ 3674 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3675 cfq_mark_cfqq_must_alloc_slice(cfqq); 3676 return ELV_MQUEUE_MUST; 3677 } 3678 3679 return ELV_MQUEUE_MAY; 3680} 3681 3682static int cfq_may_queue(struct request_queue *q, int rw) 3683{ 3684 struct cfq_data *cfqd = q->elevator->elevator_data; 3685 struct task_struct *tsk = current; 3686 struct cfq_io_context *cic; 3687 struct cfq_queue *cfqq; 3688 3689 /* 3690 * don't force setup of a queue from here, as a call to may_queue 3691 * does not necessarily imply that a request actually will be queued. 3692 * so just lookup a possibly existing queue, or return 'may queue' 3693 * if that fails 3694 */ 3695 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3696 if (!cic) 3697 return ELV_MQUEUE_MAY; 3698 3699 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3700 if (cfqq) { 3701 cfq_init_prio_data(cfqq, cic->ioc); 3702 3703 return __cfq_may_queue(cfqq); 3704 } 3705 3706 return ELV_MQUEUE_MAY; 3707} 3708 3709/* 3710 * queue lock held here 3711 */ 3712static void cfq_put_request(struct request *rq) 3713{ 3714 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3715 3716 if (cfqq) { 3717 const int rw = rq_data_dir(rq); 3718 3719 BUG_ON(!cfqq->allocated[rw]); 3720 cfqq->allocated[rw]--; 3721 3722 put_io_context(RQ_CIC(rq)->ioc); 3723 3724 rq->elevator_private[0] = NULL; 3725 rq->elevator_private[1] = NULL; 3726 3727 /* Put down rq reference on cfqg */ 3728 cfq_put_cfqg(RQ_CFQG(rq)); 3729 rq->elevator_private[2] = NULL; 3730 3731 cfq_put_queue(cfqq); 3732 } 3733} 3734 3735static struct cfq_queue * 3736cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, 3737 struct cfq_queue *cfqq) 3738{ 3739 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3740 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3741 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3742 cfq_put_queue(cfqq); 3743 return cic_to_cfqq(cic, 1); 3744} 3745 3746/* 3747 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3748 * was the last process referring to said cfqq. 3749 */ 3750static struct cfq_queue * 3751split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) 3752{ 3753 if (cfqq_process_refs(cfqq) == 1) { 3754 cfqq->pid = current->pid; 3755 cfq_clear_cfqq_coop(cfqq); 3756 cfq_clear_cfqq_split_coop(cfqq); 3757 return cfqq; 3758 } 3759 3760 cic_set_cfqq(cic, NULL, 1); 3761 3762 cfq_put_cooperator(cfqq); 3763 3764 cfq_put_queue(cfqq); 3765 return NULL; 3766} 3767/* 3768 * Allocate cfq data structures associated with this request. 3769 */ 3770static int 3771cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3772{ 3773 struct cfq_data *cfqd = q->elevator->elevator_data; 3774 struct cfq_io_context *cic; 3775 const int rw = rq_data_dir(rq); 3776 const bool is_sync = rq_is_sync(rq); 3777 struct cfq_queue *cfqq; 3778 unsigned long flags; 3779 3780 might_sleep_if(gfp_mask & __GFP_WAIT); 3781 3782 cic = cfq_get_io_context(cfqd, gfp_mask); 3783 3784 spin_lock_irqsave(q->queue_lock, flags); 3785 3786 if (!cic) 3787 goto queue_fail; 3788 3789new_queue: 3790 cfqq = cic_to_cfqq(cic, is_sync); 3791 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3792 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); 3793 cic_set_cfqq(cic, cfqq, is_sync); 3794 } else { 3795 /* 3796 * If the queue was seeky for too long, break it apart. 3797 */ 3798 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3799 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3800 cfqq = split_cfqq(cic, cfqq); 3801 if (!cfqq) 3802 goto new_queue; 3803 } 3804 3805 /* 3806 * Check to see if this queue is scheduled to merge with 3807 * another, closely cooperating queue. The merging of 3808 * queues happens here as it must be done in process context. 3809 * The reference on new_cfqq was taken in merge_cfqqs. 3810 */ 3811 if (cfqq->new_cfqq) 3812 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3813 } 3814 3815 cfqq->allocated[rw]++; 3816 3817 cfqq->ref++; 3818 rq->elevator_private[0] = cic; 3819 rq->elevator_private[1] = cfqq; 3820 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); 3821 spin_unlock_irqrestore(q->queue_lock, flags); 3822 return 0; 3823 3824queue_fail: 3825 cfq_schedule_dispatch(cfqd); 3826 spin_unlock_irqrestore(q->queue_lock, flags); 3827 cfq_log(cfqd, "set_request fail"); 3828 return 1; 3829} 3830 3831static void cfq_kick_queue(struct work_struct *work) 3832{ 3833 struct cfq_data *cfqd = 3834 container_of(work, struct cfq_data, unplug_work); 3835 struct request_queue *q = cfqd->queue; 3836 3837 spin_lock_irq(q->queue_lock); 3838 __blk_run_queue(cfqd->queue); 3839 spin_unlock_irq(q->queue_lock); 3840} 3841 3842/* 3843 * Timer running if the active_queue is currently idling inside its time slice 3844 */ 3845static void cfq_idle_slice_timer(unsigned long data) 3846{ 3847 struct cfq_data *cfqd = (struct cfq_data *) data; 3848 struct cfq_queue *cfqq; 3849 unsigned long flags; 3850 int timed_out = 1; 3851 3852 cfq_log(cfqd, "idle timer fired"); 3853 3854 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3855 3856 cfqq = cfqd->active_queue; 3857 if (cfqq) { 3858 timed_out = 0; 3859 3860 /* 3861 * We saw a request before the queue expired, let it through 3862 */ 3863 if (cfq_cfqq_must_dispatch(cfqq)) 3864 goto out_kick; 3865 3866 /* 3867 * expired 3868 */ 3869 if (cfq_slice_used(cfqq)) 3870 goto expire; 3871 3872 /* 3873 * only expire and reinvoke request handler, if there are 3874 * other queues with pending requests 3875 */ 3876 if (!cfqd->busy_queues) 3877 goto out_cont; 3878 3879 /* 3880 * not expired and it has a request pending, let it dispatch 3881 */ 3882 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3883 goto out_kick; 3884 3885 /* 3886 * Queue depth flag is reset only when the idle didn't succeed 3887 */ 3888 cfq_clear_cfqq_deep(cfqq); 3889 } 3890expire: 3891 cfq_slice_expired(cfqd, timed_out); 3892out_kick: 3893 cfq_schedule_dispatch(cfqd); 3894out_cont: 3895 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3896} 3897 3898static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3899{ 3900 del_timer_sync(&cfqd->idle_slice_timer); 3901 cancel_work_sync(&cfqd->unplug_work); 3902} 3903 3904static void cfq_put_async_queues(struct cfq_data *cfqd) 3905{ 3906 int i; 3907 3908 for (i = 0; i < IOPRIO_BE_NR; i++) { 3909 if (cfqd->async_cfqq[0][i]) 3910 cfq_put_queue(cfqd->async_cfqq[0][i]); 3911 if (cfqd->async_cfqq[1][i]) 3912 cfq_put_queue(cfqd->async_cfqq[1][i]); 3913 } 3914 3915 if (cfqd->async_idle_cfqq) 3916 cfq_put_queue(cfqd->async_idle_cfqq); 3917} 3918 3919static void cfq_exit_queue(struct elevator_queue *e) 3920{ 3921 struct cfq_data *cfqd = e->elevator_data; 3922 struct request_queue *q = cfqd->queue; 3923 bool wait = false; 3924 3925 cfq_shutdown_timer_wq(cfqd); 3926 3927 spin_lock_irq(q->queue_lock); 3928 3929 if (cfqd->active_queue) 3930 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3931 3932 while (!list_empty(&cfqd->cic_list)) { 3933 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, 3934 struct cfq_io_context, 3935 queue_list); 3936 3937 __cfq_exit_single_io_context(cfqd, cic); 3938 } 3939 3940 cfq_put_async_queues(cfqd); 3941 cfq_release_cfq_groups(cfqd); 3942 3943 /* 3944 * If there are groups which we could not unlink from blkcg list, 3945 * wait for a rcu period for them to be freed. 3946 */ 3947 if (cfqd->nr_blkcg_linked_grps) 3948 wait = true; 3949 3950 spin_unlock_irq(q->queue_lock); 3951 3952 cfq_shutdown_timer_wq(cfqd); 3953 3954 spin_lock(&cic_index_lock); 3955 ida_remove(&cic_index_ida, cfqd->cic_index); 3956 spin_unlock(&cic_index_lock); 3957 3958 /* 3959 * Wait for cfqg->blkg->key accessors to exit their grace periods. 3960 * Do this wait only if there are other unlinked groups out 3961 * there. This can happen if cgroup deletion path claimed the 3962 * responsibility of cleaning up a group before queue cleanup code 3963 * get to the group. 3964 * 3965 * Do not call synchronize_rcu() unconditionally as there are drivers 3966 * which create/delete request queue hundreds of times during scan/boot 3967 * and synchronize_rcu() can take significant time and slow down boot. 3968 */ 3969 if (wait) 3970 synchronize_rcu(); 3971 3972#ifdef CONFIG_CFQ_GROUP_IOSCHED 3973 /* Free up per cpu stats for root group */ 3974 free_percpu(cfqd->root_group.blkg.stats_cpu); 3975#endif 3976 kfree(cfqd); 3977} 3978 3979static int cfq_alloc_cic_index(void) 3980{ 3981 int index, error; 3982 3983 do { 3984 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) 3985 return -ENOMEM; 3986 3987 spin_lock(&cic_index_lock); 3988 error = ida_get_new(&cic_index_ida, &index); 3989 spin_unlock(&cic_index_lock); 3990 if (error && error != -EAGAIN) 3991 return error; 3992 } while (error); 3993 3994 return index; 3995} 3996 3997static void *cfq_init_queue(struct request_queue *q) 3998{ 3999 struct cfq_data *cfqd; 4000 int i, j; 4001 struct cfq_group *cfqg; 4002 struct cfq_rb_root *st; 4003 4004 i = cfq_alloc_cic_index(); 4005 if (i < 0) 4006 return NULL; 4007 4008 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 4009 if (!cfqd) { 4010 spin_lock(&cic_index_lock); 4011 ida_remove(&cic_index_ida, i); 4012 spin_unlock(&cic_index_lock); 4013 return NULL; 4014 } 4015 4016 /* 4017 * Don't need take queue_lock in the routine, since we are 4018 * initializing the ioscheduler, and nobody is using cfqd 4019 */ 4020 cfqd->cic_index = i; 4021 4022 /* Init root service tree */ 4023 cfqd->grp_service_tree = CFQ_RB_ROOT; 4024 4025 /* Init root group */ 4026 cfqg = &cfqd->root_group; 4027 for_each_cfqg_st(cfqg, i, j, st) 4028 *st = CFQ_RB_ROOT; 4029 RB_CLEAR_NODE(&cfqg->rb_node); 4030 4031 /* Give preference to root group over other groups */ 4032 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 4033 4034#ifdef CONFIG_CFQ_GROUP_IOSCHED 4035 /* 4036 * Set root group reference to 2. One reference will be dropped when 4037 * all groups on cfqd->cfqg_list are being deleted during queue exit. 4038 * Other reference will remain there as we don't want to delete this 4039 * group as it is statically allocated and gets destroyed when 4040 * throtl_data goes away. 4041 */ 4042 cfqg->ref = 2; 4043 4044 if (blkio_alloc_blkg_stats(&cfqg->blkg)) { 4045 kfree(cfqg); 4046 4047 spin_lock(&cic_index_lock); 4048 ida_remove(&cic_index_ida, cfqd->cic_index); 4049 spin_unlock(&cic_index_lock); 4050 4051 kfree(cfqd); 4052 return NULL; 4053 } 4054 4055 rcu_read_lock(); 4056 4057 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, 4058 (void *)cfqd, 0); 4059 rcu_read_unlock(); 4060 cfqd->nr_blkcg_linked_grps++; 4061 4062 /* Add group on cfqd->cfqg_list */ 4063 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 4064#endif 4065 /* 4066 * Not strictly needed (since RB_ROOT just clears the node and we 4067 * zeroed cfqd on alloc), but better be safe in case someone decides 4068 * to add magic to the rb code 4069 */ 4070 for (i = 0; i < CFQ_PRIO_LISTS; i++) 4071 cfqd->prio_trees[i] = RB_ROOT; 4072 4073 /* 4074 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 4075 * Grab a permanent reference to it, so that the normal code flow 4076 * will not attempt to free it. 4077 */ 4078 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 4079 cfqd->oom_cfqq.ref++; 4080 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 4081 4082 INIT_LIST_HEAD(&cfqd->cic_list); 4083 4084 cfqd->queue = q; 4085 4086 init_timer(&cfqd->idle_slice_timer); 4087 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4088 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4089 4090 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4091 4092 cfqd->cfq_quantum = cfq_quantum; 4093 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4094 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4095 cfqd->cfq_back_max = cfq_back_max; 4096 cfqd->cfq_back_penalty = cfq_back_penalty; 4097 cfqd->cfq_slice[0] = cfq_slice_async; 4098 cfqd->cfq_slice[1] = cfq_slice_sync; 4099 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4100 cfqd->cfq_slice_idle = cfq_slice_idle; 4101 cfqd->cfq_group_idle = cfq_group_idle; 4102 cfqd->cfq_latency = 1; 4103 cfqd->hw_tag = -1; 4104 /* 4105 * we optimistically start assuming sync ops weren't delayed in last 4106 * second, in order to have larger depth for async operations. 4107 */ 4108 cfqd->last_delayed_sync = jiffies - HZ; 4109 return cfqd; 4110} 4111 4112static void cfq_slab_kill(void) 4113{ 4114 /* 4115 * Caller already ensured that pending RCU callbacks are completed, 4116 * so we should have no busy allocations at this point. 4117 */ 4118 if (cfq_pool) 4119 kmem_cache_destroy(cfq_pool); 4120 if (cfq_ioc_pool) 4121 kmem_cache_destroy(cfq_ioc_pool); 4122} 4123 4124static int __init cfq_slab_setup(void) 4125{ 4126 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4127 if (!cfq_pool) 4128 goto fail; 4129 4130 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); 4131 if (!cfq_ioc_pool) 4132 goto fail; 4133 4134 return 0; 4135fail: 4136 cfq_slab_kill(); 4137 return -ENOMEM; 4138} 4139 4140/* 4141 * sysfs parts below --> 4142 */ 4143static ssize_t 4144cfq_var_show(unsigned int var, char *page) 4145{ 4146 return sprintf(page, "%d\n", var); 4147} 4148 4149static ssize_t 4150cfq_var_store(unsigned int *var, const char *page, size_t count) 4151{ 4152 char *p = (char *) page; 4153 4154 *var = simple_strtoul(p, &p, 10); 4155 return count; 4156} 4157 4158#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4159static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4160{ \ 4161 struct cfq_data *cfqd = e->elevator_data; \ 4162 unsigned int __data = __VAR; \ 4163 if (__CONV) \ 4164 __data = jiffies_to_msecs(__data); \ 4165 return cfq_var_show(__data, (page)); \ 4166} 4167SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4168SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4169SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4170SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4171SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4172SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4173SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4174SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4175SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4176SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4177SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4178#undef SHOW_FUNCTION 4179 4180#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4181static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4182{ \ 4183 struct cfq_data *cfqd = e->elevator_data; \ 4184 unsigned int __data; \ 4185 int ret = cfq_var_store(&__data, (page), count); \ 4186 if (__data < (MIN)) \ 4187 __data = (MIN); \ 4188 else if (__data > (MAX)) \ 4189 __data = (MAX); \ 4190 if (__CONV) \ 4191 *(__PTR) = msecs_to_jiffies(__data); \ 4192 else \ 4193 *(__PTR) = __data; \ 4194 return ret; \ 4195} 4196STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4197STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4198 UINT_MAX, 1); 4199STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4200 UINT_MAX, 1); 4201STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4202STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4203 UINT_MAX, 0); 4204STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4205STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4206STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4207STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4208STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4209 UINT_MAX, 0); 4210STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4211#undef STORE_FUNCTION 4212 4213#define CFQ_ATTR(name) \ 4214 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4215 4216static struct elv_fs_entry cfq_attrs[] = { 4217 CFQ_ATTR(quantum), 4218 CFQ_ATTR(fifo_expire_sync), 4219 CFQ_ATTR(fifo_expire_async), 4220 CFQ_ATTR(back_seek_max), 4221 CFQ_ATTR(back_seek_penalty), 4222 CFQ_ATTR(slice_sync), 4223 CFQ_ATTR(slice_async), 4224 CFQ_ATTR(slice_async_rq), 4225 CFQ_ATTR(slice_idle), 4226 CFQ_ATTR(group_idle), 4227 CFQ_ATTR(low_latency), 4228 __ATTR_NULL 4229}; 4230 4231static struct elevator_type iosched_cfq = { 4232 .ops = { 4233 .elevator_merge_fn = cfq_merge, 4234 .elevator_merged_fn = cfq_merged_request, 4235 .elevator_merge_req_fn = cfq_merged_requests, 4236 .elevator_allow_merge_fn = cfq_allow_merge, 4237 .elevator_bio_merged_fn = cfq_bio_merged, 4238 .elevator_dispatch_fn = cfq_dispatch_requests, 4239 .elevator_add_req_fn = cfq_insert_request, 4240 .elevator_activate_req_fn = cfq_activate_request, 4241 .elevator_deactivate_req_fn = cfq_deactivate_request, 4242 .elevator_completed_req_fn = cfq_completed_request, 4243 .elevator_former_req_fn = elv_rb_former_request, 4244 .elevator_latter_req_fn = elv_rb_latter_request, 4245 .elevator_set_req_fn = cfq_set_request, 4246 .elevator_put_req_fn = cfq_put_request, 4247 .elevator_may_queue_fn = cfq_may_queue, 4248 .elevator_init_fn = cfq_init_queue, 4249 .elevator_exit_fn = cfq_exit_queue, 4250 .trim = cfq_free_io_context, 4251 }, 4252 .elevator_attrs = cfq_attrs, 4253 .elevator_name = "cfq", 4254 .elevator_owner = THIS_MODULE, 4255}; 4256 4257#ifdef CONFIG_CFQ_GROUP_IOSCHED 4258static struct blkio_policy_type blkio_policy_cfq = { 4259 .ops = { 4260 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 4261 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 4262 }, 4263 .plid = BLKIO_POLICY_PROP, 4264}; 4265#else 4266static struct blkio_policy_type blkio_policy_cfq; 4267#endif 4268 4269static int __init cfq_init(void) 4270{ 4271 /* 4272 * could be 0 on HZ < 1000 setups 4273 */ 4274 if (!cfq_slice_async) 4275 cfq_slice_async = 1; 4276 if (!cfq_slice_idle) 4277 cfq_slice_idle = 1; 4278 4279#ifdef CONFIG_CFQ_GROUP_IOSCHED 4280 if (!cfq_group_idle) 4281 cfq_group_idle = 1; 4282#else 4283 cfq_group_idle = 0; 4284#endif 4285 if (cfq_slab_setup()) 4286 return -ENOMEM; 4287 4288 elv_register(&iosched_cfq); 4289 blkio_policy_register(&blkio_policy_cfq); 4290 4291 return 0; 4292} 4293 4294static void __exit cfq_exit(void) 4295{ 4296 DECLARE_COMPLETION_ONSTACK(all_gone); 4297 blkio_policy_unregister(&blkio_policy_cfq); 4298 elv_unregister(&iosched_cfq); 4299 ioc_gone = &all_gone; 4300 /* ioc_gone's update must be visible before reading ioc_count */ 4301 smp_wmb(); 4302 4303 /* 4304 * this also protects us from entering cfq_slab_kill() with 4305 * pending RCU callbacks 4306 */ 4307 if (elv_ioc_count_read(cfq_ioc_count)) 4308 wait_for_completion(&all_gone); 4309 ida_destroy(&cic_index_ida); 4310 cfq_slab_kill(); 4311} 4312 4313module_init(cfq_init); 4314module_exit(cfq_exit); 4315 4316MODULE_AUTHOR("Jens Axboe"); 4317MODULE_LICENSE("GPL"); 4318MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4319