cfq-iosched.c revision ca32aefc7f2539ed88d42763330d54ee3e61769a
1/* 2 * CFQ, or complete fairness queueing, disk scheduler. 3 * 4 * Based on ideas from a previously unfinished io 5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. 6 * 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> 8 */ 9#include <linux/module.h> 10#include <linux/slab.h> 11#include <linux/blkdev.h> 12#include <linux/elevator.h> 13#include <linux/jiffies.h> 14#include <linux/rbtree.h> 15#include <linux/ioprio.h> 16#include <linux/blktrace_api.h> 17#include "blk.h" 18#include "cfq.h" 19 20/* 21 * tunables 22 */ 23/* max queue in one round of service */ 24static const int cfq_quantum = 8; 25static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 26/* maximum backwards seek, in KiB */ 27static const int cfq_back_max = 16 * 1024; 28/* penalty of a backwards seek */ 29static const int cfq_back_penalty = 2; 30static const int cfq_slice_sync = HZ / 10; 31static int cfq_slice_async = HZ / 25; 32static const int cfq_slice_async_rq = 2; 33static int cfq_slice_idle = HZ / 125; 34static int cfq_group_idle = HZ / 125; 35static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 36static const int cfq_hist_divisor = 4; 37 38/* 39 * offset from end of service tree 40 */ 41#define CFQ_IDLE_DELAY (HZ / 5) 42 43/* 44 * below this threshold, we consider thinktime immediate 45 */ 46#define CFQ_MIN_TT (2) 47 48#define CFQ_SLICE_SCALE (5) 49#define CFQ_HW_QUEUE_MIN (5) 50#define CFQ_SERVICE_SHIFT 12 51 52#define CFQQ_SEEK_THR (sector_t)(8 * 100) 53#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 54#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 55#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 56 57#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq) 58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0]) 59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1]) 60 61static struct kmem_cache *cfq_pool; 62 63#define CFQ_PRIO_LISTS IOPRIO_BE_NR 64#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 65#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 66 67#define sample_valid(samples) ((samples) > 80) 68#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 69 70struct cfq_ttime { 71 unsigned long last_end_request; 72 73 unsigned long ttime_total; 74 unsigned long ttime_samples; 75 unsigned long ttime_mean; 76}; 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 219struct cfq_io_cq { 220 struct io_cq icq; /* must be the first member */ 221 struct cfq_queue *cfqq[2]; 222 struct cfq_ttime ttime; 223}; 224 225/* 226 * Per block device queue structure 227 */ 228struct cfq_data { 229 struct request_queue *queue; 230 /* Root service tree for cfq_groups */ 231 struct cfq_rb_root grp_service_tree; 232 struct cfq_group root_group; 233 234 /* 235 * The priority currently being served 236 */ 237 enum wl_prio_t serving_prio; 238 enum wl_type_t serving_type; 239 unsigned long workload_expires; 240 struct cfq_group *serving_group; 241 242 /* 243 * Each priority tree is sorted by next_request position. These 244 * trees are used when determining if two or more queues are 245 * interleaving requests (see cfq_close_cooperator). 246 */ 247 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 248 249 unsigned int busy_queues; 250 unsigned int busy_sync_queues; 251 252 int rq_in_driver; 253 int rq_in_flight[2]; 254 255 /* 256 * queue-depth detection 257 */ 258 int rq_queued; 259 int hw_tag; 260 /* 261 * hw_tag can be 262 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 263 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 264 * 0 => no NCQ 265 */ 266 int hw_tag_est_depth; 267 unsigned int hw_tag_samples; 268 269 /* 270 * idle window management 271 */ 272 struct timer_list idle_slice_timer; 273 struct work_struct unplug_work; 274 275 struct cfq_queue *active_queue; 276 struct cfq_io_cq *active_cic; 277 278 /* 279 * async queue for each priority case 280 */ 281 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 282 struct cfq_queue *async_idle_cfqq; 283 284 sector_t last_position; 285 286 /* 287 * tunables, see top of file 288 */ 289 unsigned int cfq_quantum; 290 unsigned int cfq_fifo_expire[2]; 291 unsigned int cfq_back_penalty; 292 unsigned int cfq_back_max; 293 unsigned int cfq_slice[2]; 294 unsigned int cfq_slice_async_rq; 295 unsigned int cfq_slice_idle; 296 unsigned int cfq_group_idle; 297 unsigned int cfq_latency; 298 299 /* 300 * Fallback dummy cfqq for extreme OOM conditions 301 */ 302 struct cfq_queue oom_cfqq; 303 304 unsigned long last_delayed_sync; 305 306 /* List of cfq groups being managed on this device*/ 307 struct hlist_head cfqg_list; 308 309 /* Number of groups which are on blkcg->blkg_list */ 310 unsigned int nr_blkcg_linked_grps; 311}; 312 313static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 314 315static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 316 enum wl_prio_t prio, 317 enum wl_type_t type) 318{ 319 if (!cfqg) 320 return NULL; 321 322 if (prio == IDLE_WORKLOAD) 323 return &cfqg->service_tree_idle; 324 325 return &cfqg->service_trees[prio][type]; 326} 327 328enum cfqq_state_flags { 329 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 330 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 331 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 332 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 333 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 334 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 335 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 336 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 337 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 338 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 339 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 340 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 341 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 342}; 343 344#define CFQ_CFQQ_FNS(name) \ 345static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 346{ \ 347 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 348} \ 349static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 350{ \ 351 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 352} \ 353static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 354{ \ 355 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 356} 357 358CFQ_CFQQ_FNS(on_rr); 359CFQ_CFQQ_FNS(wait_request); 360CFQ_CFQQ_FNS(must_dispatch); 361CFQ_CFQQ_FNS(must_alloc_slice); 362CFQ_CFQQ_FNS(fifo_expire); 363CFQ_CFQQ_FNS(idle_window); 364CFQ_CFQQ_FNS(prio_changed); 365CFQ_CFQQ_FNS(slice_new); 366CFQ_CFQQ_FNS(sync); 367CFQ_CFQQ_FNS(coop); 368CFQ_CFQQ_FNS(split_coop); 369CFQ_CFQQ_FNS(deep); 370CFQ_CFQQ_FNS(wait_busy); 371#undef CFQ_CFQQ_FNS 372 373#ifdef CONFIG_CFQ_GROUP_IOSCHED 374#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 375 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 376 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 377 blkg_path(&(cfqq)->cfqg->blkg), ##args) 378 379#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 380 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 381 blkg_path(&(cfqg)->blkg), ##args) \ 382 383#else 384#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 385 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 386#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 387#endif 388#define cfq_log(cfqd, fmt, args...) \ 389 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 390 391/* Traverses through cfq group service trees */ 392#define for_each_cfqg_st(cfqg, i, j, st) \ 393 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 394 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 395 : &cfqg->service_tree_idle; \ 396 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 397 (i == IDLE_WORKLOAD && j == 0); \ 398 j++, st = i < IDLE_WORKLOAD ? \ 399 &cfqg->service_trees[i][j]: NULL) \ 400 401static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, 402 struct cfq_ttime *ttime, bool group_idle) 403{ 404 unsigned long slice; 405 if (!sample_valid(ttime->ttime_samples)) 406 return false; 407 if (group_idle) 408 slice = cfqd->cfq_group_idle; 409 else 410 slice = cfqd->cfq_slice_idle; 411 return ttime->ttime_mean > slice; 412} 413 414static inline bool iops_mode(struct cfq_data *cfqd) 415{ 416 /* 417 * If we are not idling on queues and it is a NCQ drive, parallel 418 * execution of requests is on and measuring time is not possible 419 * in most of the cases until and unless we drive shallower queue 420 * depths and that becomes a performance bottleneck. In such cases 421 * switch to start providing fairness in terms of number of IOs. 422 */ 423 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 424 return true; 425 else 426 return false; 427} 428 429static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 430{ 431 if (cfq_class_idle(cfqq)) 432 return IDLE_WORKLOAD; 433 if (cfq_class_rt(cfqq)) 434 return RT_WORKLOAD; 435 return BE_WORKLOAD; 436} 437 438 439static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 440{ 441 if (!cfq_cfqq_sync(cfqq)) 442 return ASYNC_WORKLOAD; 443 if (!cfq_cfqq_idle_window(cfqq)) 444 return SYNC_NOIDLE_WORKLOAD; 445 return SYNC_WORKLOAD; 446} 447 448static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 449 struct cfq_data *cfqd, 450 struct cfq_group *cfqg) 451{ 452 if (wl == IDLE_WORKLOAD) 453 return cfqg->service_tree_idle.count; 454 455 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 456 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 457 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 458} 459 460static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 461 struct cfq_group *cfqg) 462{ 463 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 464 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 465} 466 467static void cfq_dispatch_insert(struct request_queue *, struct request *); 468static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, 469 struct io_context *, gfp_t); 470 471static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq) 472{ 473 /* cic->icq is the first member, %NULL will convert to %NULL */ 474 return container_of(icq, struct cfq_io_cq, icq); 475} 476 477static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd, 478 struct io_context *ioc) 479{ 480 if (ioc) 481 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue)); 482 return NULL; 483} 484 485static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync) 486{ 487 return cic->cfqq[is_sync]; 488} 489 490static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq, 491 bool is_sync) 492{ 493 cic->cfqq[is_sync] = cfqq; 494} 495 496static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic) 497{ 498 return cic->icq.q->elevator->elevator_data; 499} 500 501/* 502 * We regard a request as SYNC, if it's either a read or has the SYNC bit 503 * set (in which case it could also be direct WRITE). 504 */ 505static inline bool cfq_bio_sync(struct bio *bio) 506{ 507 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 508} 509 510/* 511 * scheduler run of queue, if there are requests pending and no one in the 512 * driver that will restart queueing 513 */ 514static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 515{ 516 if (cfqd->busy_queues) { 517 cfq_log(cfqd, "schedule dispatch"); 518 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 519 } 520} 521 522/* 523 * Scale schedule slice based on io priority. Use the sync time slice only 524 * if a queue is marked sync and has sync io queued. A sync queue with async 525 * io only, should not get full sync slice length. 526 */ 527static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 528 unsigned short prio) 529{ 530 const int base_slice = cfqd->cfq_slice[sync]; 531 532 WARN_ON(prio >= IOPRIO_BE_NR); 533 534 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 535} 536 537static inline int 538cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 539{ 540 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 541} 542 543static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 544{ 545 u64 d = delta << CFQ_SERVICE_SHIFT; 546 547 d = d * BLKIO_WEIGHT_DEFAULT; 548 do_div(d, cfqg->weight); 549 return d; 550} 551 552static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 553{ 554 s64 delta = (s64)(vdisktime - min_vdisktime); 555 if (delta > 0) 556 min_vdisktime = vdisktime; 557 558 return min_vdisktime; 559} 560 561static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 562{ 563 s64 delta = (s64)(vdisktime - min_vdisktime); 564 if (delta < 0) 565 min_vdisktime = vdisktime; 566 567 return min_vdisktime; 568} 569 570static void update_min_vdisktime(struct cfq_rb_root *st) 571{ 572 struct cfq_group *cfqg; 573 574 if (st->left) { 575 cfqg = rb_entry_cfqg(st->left); 576 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 577 cfqg->vdisktime); 578 } 579} 580 581/* 582 * get averaged number of queues of RT/BE priority. 583 * average is updated, with a formula that gives more weight to higher numbers, 584 * to quickly follows sudden increases and decrease slowly 585 */ 586 587static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 588 struct cfq_group *cfqg, bool rt) 589{ 590 unsigned min_q, max_q; 591 unsigned mult = cfq_hist_divisor - 1; 592 unsigned round = cfq_hist_divisor / 2; 593 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 594 595 min_q = min(cfqg->busy_queues_avg[rt], busy); 596 max_q = max(cfqg->busy_queues_avg[rt], busy); 597 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 598 cfq_hist_divisor; 599 return cfqg->busy_queues_avg[rt]; 600} 601 602static inline unsigned 603cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 604{ 605 struct cfq_rb_root *st = &cfqd->grp_service_tree; 606 607 return cfq_target_latency * cfqg->weight / st->total_weight; 608} 609 610static inline unsigned 611cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 612{ 613 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 614 if (cfqd->cfq_latency) { 615 /* 616 * interested queues (we consider only the ones with the same 617 * priority class in the cfq group) 618 */ 619 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 620 cfq_class_rt(cfqq)); 621 unsigned sync_slice = cfqd->cfq_slice[1]; 622 unsigned expect_latency = sync_slice * iq; 623 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 624 625 if (expect_latency > group_slice) { 626 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 627 /* scale low_slice according to IO priority 628 * and sync vs async */ 629 unsigned low_slice = 630 min(slice, base_low_slice * slice / sync_slice); 631 /* the adapted slice value is scaled to fit all iqs 632 * into the target latency */ 633 slice = max(slice * group_slice / expect_latency, 634 low_slice); 635 } 636 } 637 return slice; 638} 639 640static inline void 641cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 642{ 643 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 644 645 cfqq->slice_start = jiffies; 646 cfqq->slice_end = jiffies + slice; 647 cfqq->allocated_slice = slice; 648 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 649} 650 651/* 652 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 653 * isn't valid until the first request from the dispatch is activated 654 * and the slice time set. 655 */ 656static inline bool cfq_slice_used(struct cfq_queue *cfqq) 657{ 658 if (cfq_cfqq_slice_new(cfqq)) 659 return false; 660 if (time_before(jiffies, cfqq->slice_end)) 661 return false; 662 663 return true; 664} 665 666/* 667 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 668 * We choose the request that is closest to the head right now. Distance 669 * behind the head is penalized and only allowed to a certain extent. 670 */ 671static struct request * 672cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 673{ 674 sector_t s1, s2, d1 = 0, d2 = 0; 675 unsigned long back_max; 676#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 677#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 678 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 679 680 if (rq1 == NULL || rq1 == rq2) 681 return rq2; 682 if (rq2 == NULL) 683 return rq1; 684 685 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 686 return rq_is_sync(rq1) ? rq1 : rq2; 687 688 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) 689 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; 690 691 s1 = blk_rq_pos(rq1); 692 s2 = blk_rq_pos(rq2); 693 694 /* 695 * by definition, 1KiB is 2 sectors 696 */ 697 back_max = cfqd->cfq_back_max * 2; 698 699 /* 700 * Strict one way elevator _except_ in the case where we allow 701 * short backward seeks which are biased as twice the cost of a 702 * similar forward seek. 703 */ 704 if (s1 >= last) 705 d1 = s1 - last; 706 else if (s1 + back_max >= last) 707 d1 = (last - s1) * cfqd->cfq_back_penalty; 708 else 709 wrap |= CFQ_RQ1_WRAP; 710 711 if (s2 >= last) 712 d2 = s2 - last; 713 else if (s2 + back_max >= last) 714 d2 = (last - s2) * cfqd->cfq_back_penalty; 715 else 716 wrap |= CFQ_RQ2_WRAP; 717 718 /* Found required data */ 719 720 /* 721 * By doing switch() on the bit mask "wrap" we avoid having to 722 * check two variables for all permutations: --> faster! 723 */ 724 switch (wrap) { 725 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 726 if (d1 < d2) 727 return rq1; 728 else if (d2 < d1) 729 return rq2; 730 else { 731 if (s1 >= s2) 732 return rq1; 733 else 734 return rq2; 735 } 736 737 case CFQ_RQ2_WRAP: 738 return rq1; 739 case CFQ_RQ1_WRAP: 740 return rq2; 741 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 742 default: 743 /* 744 * Since both rqs are wrapped, 745 * start with the one that's further behind head 746 * (--> only *one* back seek required), 747 * since back seek takes more time than forward. 748 */ 749 if (s1 <= s2) 750 return rq1; 751 else 752 return rq2; 753 } 754} 755 756/* 757 * The below is leftmost cache rbtree addon 758 */ 759static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 760{ 761 /* Service tree is empty */ 762 if (!root->count) 763 return NULL; 764 765 if (!root->left) 766 root->left = rb_first(&root->rb); 767 768 if (root->left) 769 return rb_entry(root->left, struct cfq_queue, rb_node); 770 771 return NULL; 772} 773 774static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 775{ 776 if (!root->left) 777 root->left = rb_first(&root->rb); 778 779 if (root->left) 780 return rb_entry_cfqg(root->left); 781 782 return NULL; 783} 784 785static void rb_erase_init(struct rb_node *n, struct rb_root *root) 786{ 787 rb_erase(n, root); 788 RB_CLEAR_NODE(n); 789} 790 791static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 792{ 793 if (root->left == n) 794 root->left = NULL; 795 rb_erase_init(n, &root->rb); 796 --root->count; 797} 798 799/* 800 * would be nice to take fifo expire time into account as well 801 */ 802static struct request * 803cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 804 struct request *last) 805{ 806 struct rb_node *rbnext = rb_next(&last->rb_node); 807 struct rb_node *rbprev = rb_prev(&last->rb_node); 808 struct request *next = NULL, *prev = NULL; 809 810 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 811 812 if (rbprev) 813 prev = rb_entry_rq(rbprev); 814 815 if (rbnext) 816 next = rb_entry_rq(rbnext); 817 else { 818 rbnext = rb_first(&cfqq->sort_list); 819 if (rbnext && rbnext != &last->rb_node) 820 next = rb_entry_rq(rbnext); 821 } 822 823 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 824} 825 826static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 827 struct cfq_queue *cfqq) 828{ 829 /* 830 * just an approximation, should be ok. 831 */ 832 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 833 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 834} 835 836static inline s64 837cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 838{ 839 return cfqg->vdisktime - st->min_vdisktime; 840} 841 842static void 843__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 844{ 845 struct rb_node **node = &st->rb.rb_node; 846 struct rb_node *parent = NULL; 847 struct cfq_group *__cfqg; 848 s64 key = cfqg_key(st, cfqg); 849 int left = 1; 850 851 while (*node != NULL) { 852 parent = *node; 853 __cfqg = rb_entry_cfqg(parent); 854 855 if (key < cfqg_key(st, __cfqg)) 856 node = &parent->rb_left; 857 else { 858 node = &parent->rb_right; 859 left = 0; 860 } 861 } 862 863 if (left) 864 st->left = &cfqg->rb_node; 865 866 rb_link_node(&cfqg->rb_node, parent, node); 867 rb_insert_color(&cfqg->rb_node, &st->rb); 868} 869 870static void 871cfq_update_group_weight(struct cfq_group *cfqg) 872{ 873 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 874 if (cfqg->needs_update) { 875 cfqg->weight = cfqg->new_weight; 876 cfqg->needs_update = false; 877 } 878} 879 880static void 881cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 882{ 883 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 884 885 cfq_update_group_weight(cfqg); 886 __cfq_group_service_tree_add(st, cfqg); 887 st->total_weight += cfqg->weight; 888} 889 890static void 891cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 892{ 893 struct cfq_rb_root *st = &cfqd->grp_service_tree; 894 struct cfq_group *__cfqg; 895 struct rb_node *n; 896 897 cfqg->nr_cfqq++; 898 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 899 return; 900 901 /* 902 * Currently put the group at the end. Later implement something 903 * so that groups get lesser vtime based on their weights, so that 904 * if group does not loose all if it was not continuously backlogged. 905 */ 906 n = rb_last(&st->rb); 907 if (n) { 908 __cfqg = rb_entry_cfqg(n); 909 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 910 } else 911 cfqg->vdisktime = st->min_vdisktime; 912 cfq_group_service_tree_add(st, cfqg); 913} 914 915static void 916cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 917{ 918 st->total_weight -= cfqg->weight; 919 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 920 cfq_rb_erase(&cfqg->rb_node, st); 921} 922 923static void 924cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 925{ 926 struct cfq_rb_root *st = &cfqd->grp_service_tree; 927 928 BUG_ON(cfqg->nr_cfqq < 1); 929 cfqg->nr_cfqq--; 930 931 /* If there are other cfq queues under this group, don't delete it */ 932 if (cfqg->nr_cfqq) 933 return; 934 935 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 936 cfq_group_service_tree_del(st, cfqg); 937 cfqg->saved_workload_slice = 0; 938 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); 939} 940 941static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 942 unsigned int *unaccounted_time) 943{ 944 unsigned int slice_used; 945 946 /* 947 * Queue got expired before even a single request completed or 948 * got expired immediately after first request completion. 949 */ 950 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 951 /* 952 * Also charge the seek time incurred to the group, otherwise 953 * if there are mutiple queues in the group, each can dispatch 954 * a single request on seeky media and cause lots of seek time 955 * and group will never know it. 956 */ 957 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 958 1); 959 } else { 960 slice_used = jiffies - cfqq->slice_start; 961 if (slice_used > cfqq->allocated_slice) { 962 *unaccounted_time = slice_used - cfqq->allocated_slice; 963 slice_used = cfqq->allocated_slice; 964 } 965 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 966 *unaccounted_time += cfqq->slice_start - 967 cfqq->dispatch_start; 968 } 969 970 return slice_used; 971} 972 973static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 974 struct cfq_queue *cfqq) 975{ 976 struct cfq_rb_root *st = &cfqd->grp_service_tree; 977 unsigned int used_sl, charge, unaccounted_sl = 0; 978 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 979 - cfqg->service_tree_idle.count; 980 981 BUG_ON(nr_sync < 0); 982 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 983 984 if (iops_mode(cfqd)) 985 charge = cfqq->slice_dispatch; 986 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 987 charge = cfqq->allocated_slice; 988 989 /* Can't update vdisktime while group is on service tree */ 990 cfq_group_service_tree_del(st, cfqg); 991 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 992 /* If a new weight was requested, update now, off tree */ 993 cfq_group_service_tree_add(st, cfqg); 994 995 /* This group is being expired. Save the context */ 996 if (time_after(cfqd->workload_expires, jiffies)) { 997 cfqg->saved_workload_slice = cfqd->workload_expires 998 - jiffies; 999 cfqg->saved_workload = cfqd->serving_type; 1000 cfqg->saved_serving_prio = cfqd->serving_prio; 1001 } else 1002 cfqg->saved_workload_slice = 0; 1003 1004 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 1005 st->min_vdisktime); 1006 cfq_log_cfqq(cfqq->cfqd, cfqq, 1007 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 1008 used_sl, cfqq->slice_dispatch, charge, 1009 iops_mode(cfqd), cfqq->nr_sectors); 1010 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, 1011 unaccounted_sl); 1012 cfq_blkiocg_set_start_empty_time(&cfqg->blkg); 1013} 1014 1015#ifdef CONFIG_CFQ_GROUP_IOSCHED 1016static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 1017{ 1018 if (blkg) 1019 return container_of(blkg, struct cfq_group, blkg); 1020 return NULL; 1021} 1022 1023static void cfq_update_blkio_group_weight(struct request_queue *q, 1024 struct blkio_group *blkg, 1025 unsigned int weight) 1026{ 1027 struct cfq_group *cfqg = cfqg_of_blkg(blkg); 1028 cfqg->new_weight = weight; 1029 cfqg->needs_update = true; 1030} 1031 1032static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, 1033 struct cfq_group *cfqg, struct blkio_cgroup *blkcg) 1034{ 1035 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1036 unsigned int major, minor; 1037 1038 /* 1039 * Add group onto cgroup list. It might happen that bdi->dev is 1040 * not initialized yet. Initialize this new group without major 1041 * and minor info and this info will be filled in once a new thread 1042 * comes for IO. 1043 */ 1044 if (bdi->dev) { 1045 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1046 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1047 cfqd->queue, MKDEV(major, minor)); 1048 } else 1049 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1050 cfqd->queue, 0); 1051 1052 cfqd->nr_blkcg_linked_grps++; 1053 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); 1054 1055 /* Add group on cfqd list */ 1056 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 1057} 1058 1059/* 1060 * Should be called from sleepable context. No request queue lock as per 1061 * cpu stats are allocated dynamically and alloc_percpu needs to be called 1062 * from sleepable context. 1063 */ 1064static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) 1065{ 1066 struct cfq_group *cfqg = NULL; 1067 int i, j, ret; 1068 struct cfq_rb_root *st; 1069 1070 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 1071 if (!cfqg) 1072 return NULL; 1073 1074 for_each_cfqg_st(cfqg, i, j, st) 1075 *st = CFQ_RB_ROOT; 1076 RB_CLEAR_NODE(&cfqg->rb_node); 1077 1078 cfqg->ttime.last_end_request = jiffies; 1079 1080 /* 1081 * Take the initial reference that will be released on destroy 1082 * This can be thought of a joint reference by cgroup and 1083 * elevator which will be dropped by either elevator exit 1084 * or cgroup deletion path depending on who is exiting first. 1085 */ 1086 cfqg->ref = 1; 1087 1088 ret = blkio_alloc_blkg_stats(&cfqg->blkg); 1089 if (ret) { 1090 kfree(cfqg); 1091 return NULL; 1092 } 1093 1094 return cfqg; 1095} 1096 1097static struct cfq_group * 1098cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) 1099{ 1100 struct cfq_group *cfqg = NULL; 1101 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1102 unsigned int major, minor; 1103 1104 /* 1105 * This is the common case when there are no blkio cgroups. 1106 * Avoid lookup in this case 1107 */ 1108 if (blkcg == &blkio_root_cgroup) 1109 cfqg = &cfqd->root_group; 1110 else 1111 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, cfqd->queue, 1112 BLKIO_POLICY_PROP)); 1113 1114 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { 1115 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1116 cfqg->blkg.dev = MKDEV(major, minor); 1117 } 1118 1119 return cfqg; 1120} 1121 1122/* 1123 * Search for the cfq group current task belongs to. request_queue lock must 1124 * be held. 1125 */ 1126static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, 1127 struct blkio_cgroup *blkcg) 1128{ 1129 struct cfq_group *cfqg = NULL, *__cfqg = NULL; 1130 struct request_queue *q = cfqd->queue; 1131 1132 cfqg = cfq_find_cfqg(cfqd, blkcg); 1133 if (cfqg) 1134 return cfqg; 1135 1136 if (!css_tryget(&blkcg->css)) 1137 return NULL; 1138 1139 /* 1140 * Need to allocate a group. Allocation of group also needs allocation 1141 * of per cpu stats which in-turn takes a mutex() and can block. Hence 1142 * we need to drop rcu lock and queue_lock before we call alloc. 1143 * 1144 * Not taking any queue reference here and assuming that queue is 1145 * around by the time we return. CFQ queue allocation code does 1146 * the same. It might be racy though. 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 rcu_read_lock(); 1155 css_put(&blkcg->css); 1156 1157 /* 1158 * If some other thread already allocated the group while we were 1159 * not holding queue lock, free up the group 1160 */ 1161 __cfqg = cfq_find_cfqg(cfqd, blkcg); 1162 1163 if (__cfqg) { 1164 kfree(cfqg); 1165 return __cfqg; 1166 } 1167 1168 if (!cfqg) 1169 cfqg = &cfqd->root_group; 1170 1171 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); 1172 return cfqg; 1173} 1174 1175static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1176{ 1177 cfqg->ref++; 1178 return cfqg; 1179} 1180 1181static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1182{ 1183 /* Currently, all async queues are mapped to root group */ 1184 if (!cfq_cfqq_sync(cfqq)) 1185 cfqg = &cfqq->cfqd->root_group; 1186 1187 cfqq->cfqg = cfqg; 1188 /* cfqq reference on cfqg */ 1189 cfqq->cfqg->ref++; 1190} 1191 1192static void cfq_put_cfqg(struct cfq_group *cfqg) 1193{ 1194 struct cfq_rb_root *st; 1195 int i, j; 1196 1197 BUG_ON(cfqg->ref <= 0); 1198 cfqg->ref--; 1199 if (cfqg->ref) 1200 return; 1201 for_each_cfqg_st(cfqg, i, j, st) 1202 BUG_ON(!RB_EMPTY_ROOT(&st->rb)); 1203 free_percpu(cfqg->blkg.stats_cpu); 1204 kfree(cfqg); 1205} 1206 1207static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1208{ 1209 /* Something wrong if we are trying to remove same group twice */ 1210 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1211 1212 hlist_del_init(&cfqg->cfqd_node); 1213 1214 BUG_ON(cfqd->nr_blkcg_linked_grps <= 0); 1215 cfqd->nr_blkcg_linked_grps--; 1216 1217 /* 1218 * Put the reference taken at the time of creation so that when all 1219 * queues are gone, group can be destroyed. 1220 */ 1221 cfq_put_cfqg(cfqg); 1222} 1223 1224static bool cfq_release_cfq_groups(struct cfq_data *cfqd) 1225{ 1226 struct hlist_node *pos, *n; 1227 struct cfq_group *cfqg; 1228 bool empty = true; 1229 1230 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1231 /* 1232 * If cgroup removal path got to blk_group first and removed 1233 * it from cgroup list, then it will take care of destroying 1234 * cfqg also. 1235 */ 1236 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) 1237 cfq_destroy_cfqg(cfqd, cfqg); 1238 else 1239 empty = false; 1240 } 1241 return empty; 1242} 1243 1244/* 1245 * Blk cgroup controller notification saying that blkio_group object is being 1246 * delinked as associated cgroup object is going away. That also means that 1247 * no new IO will come in this group. So get rid of this group as soon as 1248 * any pending IO in the group is finished. 1249 * 1250 * This function is called under rcu_read_lock(). key is the rcu protected 1251 * pointer. That means @q is a valid request_queue pointer as long as we 1252 * are rcu read lock. 1253 * 1254 * @q was fetched from blkio_group under blkio_cgroup->lock. That means 1255 * it should not be NULL as even if elevator was exiting, cgroup deltion 1256 * path got to it first. 1257 */ 1258static void cfq_unlink_blkio_group(struct request_queue *q, 1259 struct blkio_group *blkg) 1260{ 1261 struct cfq_data *cfqd = q->elevator->elevator_data; 1262 unsigned long flags; 1263 1264 spin_lock_irqsave(q->queue_lock, flags); 1265 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1266 spin_unlock_irqrestore(q->queue_lock, flags); 1267} 1268 1269static struct elevator_type iosched_cfq; 1270 1271static bool cfq_clear_queue(struct request_queue *q) 1272{ 1273 lockdep_assert_held(q->queue_lock); 1274 1275 /* shoot down blkgs iff the current elevator is cfq */ 1276 if (!q->elevator || q->elevator->type != &iosched_cfq) 1277 return true; 1278 1279 return cfq_release_cfq_groups(q->elevator->elevator_data); 1280} 1281 1282#else /* GROUP_IOSCHED */ 1283static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, 1284 struct blkio_cgroup *blkcg) 1285{ 1286 return &cfqd->root_group; 1287} 1288 1289static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1290{ 1291 return cfqg; 1292} 1293 1294static inline void 1295cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1296 cfqq->cfqg = cfqg; 1297} 1298 1299static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1300static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1301 1302#endif /* GROUP_IOSCHED */ 1303 1304/* 1305 * The cfqd->service_trees holds all pending cfq_queue's that have 1306 * requests waiting to be processed. It is sorted in the order that 1307 * we will service the queues. 1308 */ 1309static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1310 bool add_front) 1311{ 1312 struct rb_node **p, *parent; 1313 struct cfq_queue *__cfqq; 1314 unsigned long rb_key; 1315 struct cfq_rb_root *service_tree; 1316 int left; 1317 int new_cfqq = 1; 1318 1319 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1320 cfqq_type(cfqq)); 1321 if (cfq_class_idle(cfqq)) { 1322 rb_key = CFQ_IDLE_DELAY; 1323 parent = rb_last(&service_tree->rb); 1324 if (parent && parent != &cfqq->rb_node) { 1325 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1326 rb_key += __cfqq->rb_key; 1327 } else 1328 rb_key += jiffies; 1329 } else if (!add_front) { 1330 /* 1331 * Get our rb key offset. Subtract any residual slice 1332 * value carried from last service. A negative resid 1333 * count indicates slice overrun, and this should position 1334 * the next service time further away in the tree. 1335 */ 1336 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1337 rb_key -= cfqq->slice_resid; 1338 cfqq->slice_resid = 0; 1339 } else { 1340 rb_key = -HZ; 1341 __cfqq = cfq_rb_first(service_tree); 1342 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1343 } 1344 1345 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1346 new_cfqq = 0; 1347 /* 1348 * same position, nothing more to do 1349 */ 1350 if (rb_key == cfqq->rb_key && 1351 cfqq->service_tree == service_tree) 1352 return; 1353 1354 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1355 cfqq->service_tree = NULL; 1356 } 1357 1358 left = 1; 1359 parent = NULL; 1360 cfqq->service_tree = service_tree; 1361 p = &service_tree->rb.rb_node; 1362 while (*p) { 1363 struct rb_node **n; 1364 1365 parent = *p; 1366 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1367 1368 /* 1369 * sort by key, that represents service time. 1370 */ 1371 if (time_before(rb_key, __cfqq->rb_key)) 1372 n = &(*p)->rb_left; 1373 else { 1374 n = &(*p)->rb_right; 1375 left = 0; 1376 } 1377 1378 p = n; 1379 } 1380 1381 if (left) 1382 service_tree->left = &cfqq->rb_node; 1383 1384 cfqq->rb_key = rb_key; 1385 rb_link_node(&cfqq->rb_node, parent, p); 1386 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1387 service_tree->count++; 1388 if (add_front || !new_cfqq) 1389 return; 1390 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1391} 1392 1393static struct cfq_queue * 1394cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1395 sector_t sector, struct rb_node **ret_parent, 1396 struct rb_node ***rb_link) 1397{ 1398 struct rb_node **p, *parent; 1399 struct cfq_queue *cfqq = NULL; 1400 1401 parent = NULL; 1402 p = &root->rb_node; 1403 while (*p) { 1404 struct rb_node **n; 1405 1406 parent = *p; 1407 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1408 1409 /* 1410 * Sort strictly based on sector. Smallest to the left, 1411 * largest to the right. 1412 */ 1413 if (sector > blk_rq_pos(cfqq->next_rq)) 1414 n = &(*p)->rb_right; 1415 else if (sector < blk_rq_pos(cfqq->next_rq)) 1416 n = &(*p)->rb_left; 1417 else 1418 break; 1419 p = n; 1420 cfqq = NULL; 1421 } 1422 1423 *ret_parent = parent; 1424 if (rb_link) 1425 *rb_link = p; 1426 return cfqq; 1427} 1428 1429static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1430{ 1431 struct rb_node **p, *parent; 1432 struct cfq_queue *__cfqq; 1433 1434 if (cfqq->p_root) { 1435 rb_erase(&cfqq->p_node, cfqq->p_root); 1436 cfqq->p_root = NULL; 1437 } 1438 1439 if (cfq_class_idle(cfqq)) 1440 return; 1441 if (!cfqq->next_rq) 1442 return; 1443 1444 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1445 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1446 blk_rq_pos(cfqq->next_rq), &parent, &p); 1447 if (!__cfqq) { 1448 rb_link_node(&cfqq->p_node, parent, p); 1449 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1450 } else 1451 cfqq->p_root = NULL; 1452} 1453 1454/* 1455 * Update cfqq's position in the service tree. 1456 */ 1457static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1458{ 1459 /* 1460 * Resorting requires the cfqq to be on the RR list already. 1461 */ 1462 if (cfq_cfqq_on_rr(cfqq)) { 1463 cfq_service_tree_add(cfqd, cfqq, 0); 1464 cfq_prio_tree_add(cfqd, cfqq); 1465 } 1466} 1467 1468/* 1469 * add to busy list of queues for service, trying to be fair in ordering 1470 * the pending list according to last request service 1471 */ 1472static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1473{ 1474 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1475 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1476 cfq_mark_cfqq_on_rr(cfqq); 1477 cfqd->busy_queues++; 1478 if (cfq_cfqq_sync(cfqq)) 1479 cfqd->busy_sync_queues++; 1480 1481 cfq_resort_rr_list(cfqd, cfqq); 1482} 1483 1484/* 1485 * Called when the cfqq no longer has requests pending, remove it from 1486 * the service tree. 1487 */ 1488static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1489{ 1490 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1491 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1492 cfq_clear_cfqq_on_rr(cfqq); 1493 1494 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1495 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1496 cfqq->service_tree = NULL; 1497 } 1498 if (cfqq->p_root) { 1499 rb_erase(&cfqq->p_node, cfqq->p_root); 1500 cfqq->p_root = NULL; 1501 } 1502 1503 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1504 BUG_ON(!cfqd->busy_queues); 1505 cfqd->busy_queues--; 1506 if (cfq_cfqq_sync(cfqq)) 1507 cfqd->busy_sync_queues--; 1508} 1509 1510/* 1511 * rb tree support functions 1512 */ 1513static void cfq_del_rq_rb(struct request *rq) 1514{ 1515 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1516 const int sync = rq_is_sync(rq); 1517 1518 BUG_ON(!cfqq->queued[sync]); 1519 cfqq->queued[sync]--; 1520 1521 elv_rb_del(&cfqq->sort_list, rq); 1522 1523 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1524 /* 1525 * Queue will be deleted from service tree when we actually 1526 * expire it later. Right now just remove it from prio tree 1527 * as it is empty. 1528 */ 1529 if (cfqq->p_root) { 1530 rb_erase(&cfqq->p_node, cfqq->p_root); 1531 cfqq->p_root = NULL; 1532 } 1533 } 1534} 1535 1536static void cfq_add_rq_rb(struct request *rq) 1537{ 1538 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1539 struct cfq_data *cfqd = cfqq->cfqd; 1540 struct request *prev; 1541 1542 cfqq->queued[rq_is_sync(rq)]++; 1543 1544 elv_rb_add(&cfqq->sort_list, rq); 1545 1546 if (!cfq_cfqq_on_rr(cfqq)) 1547 cfq_add_cfqq_rr(cfqd, cfqq); 1548 1549 /* 1550 * check if this request is a better next-serve candidate 1551 */ 1552 prev = cfqq->next_rq; 1553 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1554 1555 /* 1556 * adjust priority tree position, if ->next_rq changes 1557 */ 1558 if (prev != cfqq->next_rq) 1559 cfq_prio_tree_add(cfqd, cfqq); 1560 1561 BUG_ON(!cfqq->next_rq); 1562} 1563 1564static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1565{ 1566 elv_rb_del(&cfqq->sort_list, rq); 1567 cfqq->queued[rq_is_sync(rq)]--; 1568 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1569 rq_data_dir(rq), rq_is_sync(rq)); 1570 cfq_add_rq_rb(rq); 1571 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 1572 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), 1573 rq_is_sync(rq)); 1574} 1575 1576static struct request * 1577cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1578{ 1579 struct task_struct *tsk = current; 1580 struct cfq_io_cq *cic; 1581 struct cfq_queue *cfqq; 1582 1583 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1584 if (!cic) 1585 return NULL; 1586 1587 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1588 if (cfqq) { 1589 sector_t sector = bio->bi_sector + bio_sectors(bio); 1590 1591 return elv_rb_find(&cfqq->sort_list, sector); 1592 } 1593 1594 return NULL; 1595} 1596 1597static void cfq_activate_request(struct request_queue *q, struct request *rq) 1598{ 1599 struct cfq_data *cfqd = q->elevator->elevator_data; 1600 1601 cfqd->rq_in_driver++; 1602 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1603 cfqd->rq_in_driver); 1604 1605 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1606} 1607 1608static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1609{ 1610 struct cfq_data *cfqd = q->elevator->elevator_data; 1611 1612 WARN_ON(!cfqd->rq_in_driver); 1613 cfqd->rq_in_driver--; 1614 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1615 cfqd->rq_in_driver); 1616} 1617 1618static void cfq_remove_request(struct request *rq) 1619{ 1620 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1621 1622 if (cfqq->next_rq == rq) 1623 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1624 1625 list_del_init(&rq->queuelist); 1626 cfq_del_rq_rb(rq); 1627 1628 cfqq->cfqd->rq_queued--; 1629 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1630 rq_data_dir(rq), rq_is_sync(rq)); 1631 if (rq->cmd_flags & REQ_PRIO) { 1632 WARN_ON(!cfqq->prio_pending); 1633 cfqq->prio_pending--; 1634 } 1635} 1636 1637static int cfq_merge(struct request_queue *q, struct request **req, 1638 struct bio *bio) 1639{ 1640 struct cfq_data *cfqd = q->elevator->elevator_data; 1641 struct request *__rq; 1642 1643 __rq = cfq_find_rq_fmerge(cfqd, bio); 1644 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1645 *req = __rq; 1646 return ELEVATOR_FRONT_MERGE; 1647 } 1648 1649 return ELEVATOR_NO_MERGE; 1650} 1651 1652static void cfq_merged_request(struct request_queue *q, struct request *req, 1653 int type) 1654{ 1655 if (type == ELEVATOR_FRONT_MERGE) { 1656 struct cfq_queue *cfqq = RQ_CFQQ(req); 1657 1658 cfq_reposition_rq_rb(cfqq, req); 1659 } 1660} 1661 1662static void cfq_bio_merged(struct request_queue *q, struct request *req, 1663 struct bio *bio) 1664{ 1665 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, 1666 bio_data_dir(bio), cfq_bio_sync(bio)); 1667} 1668 1669static void 1670cfq_merged_requests(struct request_queue *q, struct request *rq, 1671 struct request *next) 1672{ 1673 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1674 struct cfq_data *cfqd = q->elevator->elevator_data; 1675 1676 /* 1677 * reposition in fifo if next is older than rq 1678 */ 1679 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1680 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1681 list_move(&rq->queuelist, &next->queuelist); 1682 rq_set_fifo_time(rq, rq_fifo_time(next)); 1683 } 1684 1685 if (cfqq->next_rq == next) 1686 cfqq->next_rq = rq; 1687 cfq_remove_request(next); 1688 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, 1689 rq_data_dir(next), rq_is_sync(next)); 1690 1691 cfqq = RQ_CFQQ(next); 1692 /* 1693 * all requests of this queue are merged to other queues, delete it 1694 * from the service tree. If it's the active_queue, 1695 * cfq_dispatch_requests() will choose to expire it or do idle 1696 */ 1697 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && 1698 cfqq != cfqd->active_queue) 1699 cfq_del_cfqq_rr(cfqd, cfqq); 1700} 1701 1702static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1703 struct bio *bio) 1704{ 1705 struct cfq_data *cfqd = q->elevator->elevator_data; 1706 struct cfq_io_cq *cic; 1707 struct cfq_queue *cfqq; 1708 1709 /* 1710 * Disallow merge of a sync bio into an async request. 1711 */ 1712 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1713 return false; 1714 1715 /* 1716 * Lookup the cfqq that this bio will be queued with and allow 1717 * merge only if rq is queued there. 1718 */ 1719 cic = cfq_cic_lookup(cfqd, current->io_context); 1720 if (!cic) 1721 return false; 1722 1723 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1724 return cfqq == RQ_CFQQ(rq); 1725} 1726 1727static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1728{ 1729 del_timer(&cfqd->idle_slice_timer); 1730 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); 1731} 1732 1733static void __cfq_set_active_queue(struct cfq_data *cfqd, 1734 struct cfq_queue *cfqq) 1735{ 1736 if (cfqq) { 1737 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1738 cfqd->serving_prio, cfqd->serving_type); 1739 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); 1740 cfqq->slice_start = 0; 1741 cfqq->dispatch_start = jiffies; 1742 cfqq->allocated_slice = 0; 1743 cfqq->slice_end = 0; 1744 cfqq->slice_dispatch = 0; 1745 cfqq->nr_sectors = 0; 1746 1747 cfq_clear_cfqq_wait_request(cfqq); 1748 cfq_clear_cfqq_must_dispatch(cfqq); 1749 cfq_clear_cfqq_must_alloc_slice(cfqq); 1750 cfq_clear_cfqq_fifo_expire(cfqq); 1751 cfq_mark_cfqq_slice_new(cfqq); 1752 1753 cfq_del_timer(cfqd, cfqq); 1754 } 1755 1756 cfqd->active_queue = cfqq; 1757} 1758 1759/* 1760 * current cfqq expired its slice (or was too idle), select new one 1761 */ 1762static void 1763__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1764 bool timed_out) 1765{ 1766 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1767 1768 if (cfq_cfqq_wait_request(cfqq)) 1769 cfq_del_timer(cfqd, cfqq); 1770 1771 cfq_clear_cfqq_wait_request(cfqq); 1772 cfq_clear_cfqq_wait_busy(cfqq); 1773 1774 /* 1775 * If this cfqq is shared between multiple processes, check to 1776 * make sure that those processes are still issuing I/Os within 1777 * the mean seek distance. If not, it may be time to break the 1778 * queues apart again. 1779 */ 1780 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1781 cfq_mark_cfqq_split_coop(cfqq); 1782 1783 /* 1784 * store what was left of this slice, if the queue idled/timed out 1785 */ 1786 if (timed_out) { 1787 if (cfq_cfqq_slice_new(cfqq)) 1788 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 1789 else 1790 cfqq->slice_resid = cfqq->slice_end - jiffies; 1791 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1792 } 1793 1794 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1795 1796 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1797 cfq_del_cfqq_rr(cfqd, cfqq); 1798 1799 cfq_resort_rr_list(cfqd, cfqq); 1800 1801 if (cfqq == cfqd->active_queue) 1802 cfqd->active_queue = NULL; 1803 1804 if (cfqd->active_cic) { 1805 put_io_context(cfqd->active_cic->icq.ioc); 1806 cfqd->active_cic = NULL; 1807 } 1808} 1809 1810static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1811{ 1812 struct cfq_queue *cfqq = cfqd->active_queue; 1813 1814 if (cfqq) 1815 __cfq_slice_expired(cfqd, cfqq, timed_out); 1816} 1817 1818/* 1819 * Get next queue for service. Unless we have a queue preemption, 1820 * we'll simply select the first cfqq in the service tree. 1821 */ 1822static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1823{ 1824 struct cfq_rb_root *service_tree = 1825 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1826 cfqd->serving_type); 1827 1828 if (!cfqd->rq_queued) 1829 return NULL; 1830 1831 /* There is nothing to dispatch */ 1832 if (!service_tree) 1833 return NULL; 1834 if (RB_EMPTY_ROOT(&service_tree->rb)) 1835 return NULL; 1836 return cfq_rb_first(service_tree); 1837} 1838 1839static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1840{ 1841 struct cfq_group *cfqg; 1842 struct cfq_queue *cfqq; 1843 int i, j; 1844 struct cfq_rb_root *st; 1845 1846 if (!cfqd->rq_queued) 1847 return NULL; 1848 1849 cfqg = cfq_get_next_cfqg(cfqd); 1850 if (!cfqg) 1851 return NULL; 1852 1853 for_each_cfqg_st(cfqg, i, j, st) 1854 if ((cfqq = cfq_rb_first(st)) != NULL) 1855 return cfqq; 1856 return NULL; 1857} 1858 1859/* 1860 * Get and set a new active queue for service. 1861 */ 1862static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1863 struct cfq_queue *cfqq) 1864{ 1865 if (!cfqq) 1866 cfqq = cfq_get_next_queue(cfqd); 1867 1868 __cfq_set_active_queue(cfqd, cfqq); 1869 return cfqq; 1870} 1871 1872static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1873 struct request *rq) 1874{ 1875 if (blk_rq_pos(rq) >= cfqd->last_position) 1876 return blk_rq_pos(rq) - cfqd->last_position; 1877 else 1878 return cfqd->last_position - blk_rq_pos(rq); 1879} 1880 1881static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1882 struct request *rq) 1883{ 1884 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1885} 1886 1887static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1888 struct cfq_queue *cur_cfqq) 1889{ 1890 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1891 struct rb_node *parent, *node; 1892 struct cfq_queue *__cfqq; 1893 sector_t sector = cfqd->last_position; 1894 1895 if (RB_EMPTY_ROOT(root)) 1896 return NULL; 1897 1898 /* 1899 * First, if we find a request starting at the end of the last 1900 * request, choose it. 1901 */ 1902 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1903 if (__cfqq) 1904 return __cfqq; 1905 1906 /* 1907 * If the exact sector wasn't found, the parent of the NULL leaf 1908 * will contain the closest sector. 1909 */ 1910 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1911 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1912 return __cfqq; 1913 1914 if (blk_rq_pos(__cfqq->next_rq) < sector) 1915 node = rb_next(&__cfqq->p_node); 1916 else 1917 node = rb_prev(&__cfqq->p_node); 1918 if (!node) 1919 return NULL; 1920 1921 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1922 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1923 return __cfqq; 1924 1925 return NULL; 1926} 1927 1928/* 1929 * cfqd - obvious 1930 * cur_cfqq - passed in so that we don't decide that the current queue is 1931 * closely cooperating with itself. 1932 * 1933 * So, basically we're assuming that that cur_cfqq has dispatched at least 1934 * one request, and that cfqd->last_position reflects a position on the disk 1935 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1936 * assumption. 1937 */ 1938static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1939 struct cfq_queue *cur_cfqq) 1940{ 1941 struct cfq_queue *cfqq; 1942 1943 if (cfq_class_idle(cur_cfqq)) 1944 return NULL; 1945 if (!cfq_cfqq_sync(cur_cfqq)) 1946 return NULL; 1947 if (CFQQ_SEEKY(cur_cfqq)) 1948 return NULL; 1949 1950 /* 1951 * Don't search priority tree if it's the only queue in the group. 1952 */ 1953 if (cur_cfqq->cfqg->nr_cfqq == 1) 1954 return NULL; 1955 1956 /* 1957 * We should notice if some of the queues are cooperating, eg 1958 * working closely on the same area of the disk. In that case, 1959 * we can group them together and don't waste time idling. 1960 */ 1961 cfqq = cfqq_close(cfqd, cur_cfqq); 1962 if (!cfqq) 1963 return NULL; 1964 1965 /* If new queue belongs to different cfq_group, don't choose it */ 1966 if (cur_cfqq->cfqg != cfqq->cfqg) 1967 return NULL; 1968 1969 /* 1970 * It only makes sense to merge sync queues. 1971 */ 1972 if (!cfq_cfqq_sync(cfqq)) 1973 return NULL; 1974 if (CFQQ_SEEKY(cfqq)) 1975 return NULL; 1976 1977 /* 1978 * Do not merge queues of different priority classes 1979 */ 1980 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1981 return NULL; 1982 1983 return cfqq; 1984} 1985 1986/* 1987 * Determine whether we should enforce idle window for this queue. 1988 */ 1989 1990static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1991{ 1992 enum wl_prio_t prio = cfqq_prio(cfqq); 1993 struct cfq_rb_root *service_tree = cfqq->service_tree; 1994 1995 BUG_ON(!service_tree); 1996 BUG_ON(!service_tree->count); 1997 1998 if (!cfqd->cfq_slice_idle) 1999 return false; 2000 2001 /* We never do for idle class queues. */ 2002 if (prio == IDLE_WORKLOAD) 2003 return false; 2004 2005 /* We do for queues that were marked with idle window flag. */ 2006 if (cfq_cfqq_idle_window(cfqq) && 2007 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 2008 return true; 2009 2010 /* 2011 * Otherwise, we do only if they are the last ones 2012 * in their service tree. 2013 */ 2014 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) && 2015 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false)) 2016 return true; 2017 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 2018 service_tree->count); 2019 return false; 2020} 2021 2022static void cfq_arm_slice_timer(struct cfq_data *cfqd) 2023{ 2024 struct cfq_queue *cfqq = cfqd->active_queue; 2025 struct cfq_io_cq *cic; 2026 unsigned long sl, group_idle = 0; 2027 2028 /* 2029 * SSD device without seek penalty, disable idling. But only do so 2030 * for devices that support queuing, otherwise we still have a problem 2031 * with sync vs async workloads. 2032 */ 2033 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 2034 return; 2035 2036 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 2037 WARN_ON(cfq_cfqq_slice_new(cfqq)); 2038 2039 /* 2040 * idle is disabled, either manually or by past process history 2041 */ 2042 if (!cfq_should_idle(cfqd, cfqq)) { 2043 /* no queue idling. Check for group idling */ 2044 if (cfqd->cfq_group_idle) 2045 group_idle = cfqd->cfq_group_idle; 2046 else 2047 return; 2048 } 2049 2050 /* 2051 * still active requests from this queue, don't idle 2052 */ 2053 if (cfqq->dispatched) 2054 return; 2055 2056 /* 2057 * task has exited, don't wait 2058 */ 2059 cic = cfqd->active_cic; 2060 if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks)) 2061 return; 2062 2063 /* 2064 * If our average think time is larger than the remaining time 2065 * slice, then don't idle. This avoids overrunning the allotted 2066 * time slice. 2067 */ 2068 if (sample_valid(cic->ttime.ttime_samples) && 2069 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { 2070 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2071 cic->ttime.ttime_mean); 2072 return; 2073 } 2074 2075 /* There are other queues in the group, don't do group idle */ 2076 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2077 return; 2078 2079 cfq_mark_cfqq_wait_request(cfqq); 2080 2081 if (group_idle) 2082 sl = cfqd->cfq_group_idle; 2083 else 2084 sl = cfqd->cfq_slice_idle; 2085 2086 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2087 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); 2088 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2089 group_idle ? 1 : 0); 2090} 2091 2092/* 2093 * Move request from internal lists to the request queue dispatch list. 2094 */ 2095static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2096{ 2097 struct cfq_data *cfqd = q->elevator->elevator_data; 2098 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2099 2100 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2101 2102 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2103 cfq_remove_request(rq); 2104 cfqq->dispatched++; 2105 (RQ_CFQG(rq))->dispatched++; 2106 elv_dispatch_sort(q, rq); 2107 2108 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2109 cfqq->nr_sectors += blk_rq_sectors(rq); 2110 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), 2111 rq_data_dir(rq), rq_is_sync(rq)); 2112} 2113 2114/* 2115 * return expired entry, or NULL to just start from scratch in rbtree 2116 */ 2117static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2118{ 2119 struct request *rq = NULL; 2120 2121 if (cfq_cfqq_fifo_expire(cfqq)) 2122 return NULL; 2123 2124 cfq_mark_cfqq_fifo_expire(cfqq); 2125 2126 if (list_empty(&cfqq->fifo)) 2127 return NULL; 2128 2129 rq = rq_entry_fifo(cfqq->fifo.next); 2130 if (time_before(jiffies, rq_fifo_time(rq))) 2131 rq = NULL; 2132 2133 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2134 return rq; 2135} 2136 2137static inline int 2138cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2139{ 2140 const int base_rq = cfqd->cfq_slice_async_rq; 2141 2142 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2143 2144 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2145} 2146 2147/* 2148 * Must be called with the queue_lock held. 2149 */ 2150static int cfqq_process_refs(struct cfq_queue *cfqq) 2151{ 2152 int process_refs, io_refs; 2153 2154 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2155 process_refs = cfqq->ref - io_refs; 2156 BUG_ON(process_refs < 0); 2157 return process_refs; 2158} 2159 2160static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2161{ 2162 int process_refs, new_process_refs; 2163 struct cfq_queue *__cfqq; 2164 2165 /* 2166 * If there are no process references on the new_cfqq, then it is 2167 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2168 * chain may have dropped their last reference (not just their 2169 * last process reference). 2170 */ 2171 if (!cfqq_process_refs(new_cfqq)) 2172 return; 2173 2174 /* Avoid a circular list and skip interim queue merges */ 2175 while ((__cfqq = new_cfqq->new_cfqq)) { 2176 if (__cfqq == cfqq) 2177 return; 2178 new_cfqq = __cfqq; 2179 } 2180 2181 process_refs = cfqq_process_refs(cfqq); 2182 new_process_refs = cfqq_process_refs(new_cfqq); 2183 /* 2184 * If the process for the cfqq has gone away, there is no 2185 * sense in merging the queues. 2186 */ 2187 if (process_refs == 0 || new_process_refs == 0) 2188 return; 2189 2190 /* 2191 * Merge in the direction of the lesser amount of work. 2192 */ 2193 if (new_process_refs >= process_refs) { 2194 cfqq->new_cfqq = new_cfqq; 2195 new_cfqq->ref += process_refs; 2196 } else { 2197 new_cfqq->new_cfqq = cfqq; 2198 cfqq->ref += new_process_refs; 2199 } 2200} 2201 2202static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 2203 struct cfq_group *cfqg, enum wl_prio_t prio) 2204{ 2205 struct cfq_queue *queue; 2206 int i; 2207 bool key_valid = false; 2208 unsigned long lowest_key = 0; 2209 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2210 2211 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2212 /* select the one with lowest rb_key */ 2213 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2214 if (queue && 2215 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2216 lowest_key = queue->rb_key; 2217 cur_best = i; 2218 key_valid = true; 2219 } 2220 } 2221 2222 return cur_best; 2223} 2224 2225static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2226{ 2227 unsigned slice; 2228 unsigned count; 2229 struct cfq_rb_root *st; 2230 unsigned group_slice; 2231 enum wl_prio_t original_prio = cfqd->serving_prio; 2232 2233 /* Choose next priority. RT > BE > IDLE */ 2234 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2235 cfqd->serving_prio = RT_WORKLOAD; 2236 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2237 cfqd->serving_prio = BE_WORKLOAD; 2238 else { 2239 cfqd->serving_prio = IDLE_WORKLOAD; 2240 cfqd->workload_expires = jiffies + 1; 2241 return; 2242 } 2243 2244 if (original_prio != cfqd->serving_prio) 2245 goto new_workload; 2246 2247 /* 2248 * For RT and BE, we have to choose also the type 2249 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2250 * expiration time 2251 */ 2252 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2253 count = st->count; 2254 2255 /* 2256 * check workload expiration, and that we still have other queues ready 2257 */ 2258 if (count && !time_after(jiffies, cfqd->workload_expires)) 2259 return; 2260 2261new_workload: 2262 /* otherwise select new workload type */ 2263 cfqd->serving_type = 2264 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2265 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2266 count = st->count; 2267 2268 /* 2269 * the workload slice is computed as a fraction of target latency 2270 * proportional to the number of queues in that workload, over 2271 * all the queues in the same priority class 2272 */ 2273 group_slice = cfq_group_slice(cfqd, cfqg); 2274 2275 slice = group_slice * count / 2276 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2277 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2278 2279 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2280 unsigned int tmp; 2281 2282 /* 2283 * Async queues are currently system wide. Just taking 2284 * proportion of queues with-in same group will lead to higher 2285 * async ratio system wide as generally root group is going 2286 * to have higher weight. A more accurate thing would be to 2287 * calculate system wide asnc/sync ratio. 2288 */ 2289 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2290 tmp = tmp/cfqd->busy_queues; 2291 slice = min_t(unsigned, slice, tmp); 2292 2293 /* async workload slice is scaled down according to 2294 * the sync/async slice ratio. */ 2295 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2296 } else 2297 /* sync workload slice is at least 2 * cfq_slice_idle */ 2298 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2299 2300 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2301 cfq_log(cfqd, "workload slice:%d", slice); 2302 cfqd->workload_expires = jiffies + slice; 2303} 2304 2305static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2306{ 2307 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2308 struct cfq_group *cfqg; 2309 2310 if (RB_EMPTY_ROOT(&st->rb)) 2311 return NULL; 2312 cfqg = cfq_rb_first_group(st); 2313 update_min_vdisktime(st); 2314 return cfqg; 2315} 2316 2317static void cfq_choose_cfqg(struct cfq_data *cfqd) 2318{ 2319 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2320 2321 cfqd->serving_group = cfqg; 2322 2323 /* Restore the workload type data */ 2324 if (cfqg->saved_workload_slice) { 2325 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2326 cfqd->serving_type = cfqg->saved_workload; 2327 cfqd->serving_prio = cfqg->saved_serving_prio; 2328 } else 2329 cfqd->workload_expires = jiffies - 1; 2330 2331 choose_service_tree(cfqd, cfqg); 2332} 2333 2334/* 2335 * Select a queue for service. If we have a current active queue, 2336 * check whether to continue servicing it, or retrieve and set a new one. 2337 */ 2338static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2339{ 2340 struct cfq_queue *cfqq, *new_cfqq = NULL; 2341 2342 cfqq = cfqd->active_queue; 2343 if (!cfqq) 2344 goto new_queue; 2345 2346 if (!cfqd->rq_queued) 2347 return NULL; 2348 2349 /* 2350 * We were waiting for group to get backlogged. Expire the queue 2351 */ 2352 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2353 goto expire; 2354 2355 /* 2356 * The active queue has run out of time, expire it and select new. 2357 */ 2358 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2359 /* 2360 * If slice had not expired at the completion of last request 2361 * we might not have turned on wait_busy flag. Don't expire 2362 * the queue yet. Allow the group to get backlogged. 2363 * 2364 * The very fact that we have used the slice, that means we 2365 * have been idling all along on this queue and it should be 2366 * ok to wait for this request to complete. 2367 */ 2368 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2369 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2370 cfqq = NULL; 2371 goto keep_queue; 2372 } else 2373 goto check_group_idle; 2374 } 2375 2376 /* 2377 * The active queue has requests and isn't expired, allow it to 2378 * dispatch. 2379 */ 2380 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2381 goto keep_queue; 2382 2383 /* 2384 * If another queue has a request waiting within our mean seek 2385 * distance, let it run. The expire code will check for close 2386 * cooperators and put the close queue at the front of the service 2387 * tree. If possible, merge the expiring queue with the new cfqq. 2388 */ 2389 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2390 if (new_cfqq) { 2391 if (!cfqq->new_cfqq) 2392 cfq_setup_merge(cfqq, new_cfqq); 2393 goto expire; 2394 } 2395 2396 /* 2397 * No requests pending. If the active queue still has requests in 2398 * flight or is idling for a new request, allow either of these 2399 * conditions to happen (or time out) before selecting a new queue. 2400 */ 2401 if (timer_pending(&cfqd->idle_slice_timer)) { 2402 cfqq = NULL; 2403 goto keep_queue; 2404 } 2405 2406 /* 2407 * This is a deep seek queue, but the device is much faster than 2408 * the queue can deliver, don't idle 2409 **/ 2410 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2411 (cfq_cfqq_slice_new(cfqq) || 2412 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2413 cfq_clear_cfqq_deep(cfqq); 2414 cfq_clear_cfqq_idle_window(cfqq); 2415 } 2416 2417 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2418 cfqq = NULL; 2419 goto keep_queue; 2420 } 2421 2422 /* 2423 * If group idle is enabled and there are requests dispatched from 2424 * this group, wait for requests to complete. 2425 */ 2426check_group_idle: 2427 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && 2428 cfqq->cfqg->dispatched && 2429 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { 2430 cfqq = NULL; 2431 goto keep_queue; 2432 } 2433 2434expire: 2435 cfq_slice_expired(cfqd, 0); 2436new_queue: 2437 /* 2438 * Current queue expired. Check if we have to switch to a new 2439 * service tree 2440 */ 2441 if (!new_cfqq) 2442 cfq_choose_cfqg(cfqd); 2443 2444 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2445keep_queue: 2446 return cfqq; 2447} 2448 2449static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2450{ 2451 int dispatched = 0; 2452 2453 while (cfqq->next_rq) { 2454 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2455 dispatched++; 2456 } 2457 2458 BUG_ON(!list_empty(&cfqq->fifo)); 2459 2460 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2461 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2462 return dispatched; 2463} 2464 2465/* 2466 * Drain our current requests. Used for barriers and when switching 2467 * io schedulers on-the-fly. 2468 */ 2469static int cfq_forced_dispatch(struct cfq_data *cfqd) 2470{ 2471 struct cfq_queue *cfqq; 2472 int dispatched = 0; 2473 2474 /* Expire the timeslice of the current active queue first */ 2475 cfq_slice_expired(cfqd, 0); 2476 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2477 __cfq_set_active_queue(cfqd, cfqq); 2478 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2479 } 2480 2481 BUG_ON(cfqd->busy_queues); 2482 2483 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2484 return dispatched; 2485} 2486 2487static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2488 struct cfq_queue *cfqq) 2489{ 2490 /* the queue hasn't finished any request, can't estimate */ 2491 if (cfq_cfqq_slice_new(cfqq)) 2492 return true; 2493 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2494 cfqq->slice_end)) 2495 return true; 2496 2497 return false; 2498} 2499 2500static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2501{ 2502 unsigned int max_dispatch; 2503 2504 /* 2505 * Drain async requests before we start sync IO 2506 */ 2507 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2508 return false; 2509 2510 /* 2511 * If this is an async queue and we have sync IO in flight, let it wait 2512 */ 2513 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2514 return false; 2515 2516 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2517 if (cfq_class_idle(cfqq)) 2518 max_dispatch = 1; 2519 2520 /* 2521 * Does this cfqq already have too much IO in flight? 2522 */ 2523 if (cfqq->dispatched >= max_dispatch) { 2524 bool promote_sync = false; 2525 /* 2526 * idle queue must always only have a single IO in flight 2527 */ 2528 if (cfq_class_idle(cfqq)) 2529 return false; 2530 2531 /* 2532 * If there is only one sync queue 2533 * we can ignore async queue here and give the sync 2534 * queue no dispatch limit. The reason is a sync queue can 2535 * preempt async queue, limiting the sync queue doesn't make 2536 * sense. This is useful for aiostress test. 2537 */ 2538 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2539 promote_sync = true; 2540 2541 /* 2542 * We have other queues, don't allow more IO from this one 2543 */ 2544 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2545 !promote_sync) 2546 return false; 2547 2548 /* 2549 * Sole queue user, no limit 2550 */ 2551 if (cfqd->busy_queues == 1 || promote_sync) 2552 max_dispatch = -1; 2553 else 2554 /* 2555 * Normally we start throttling cfqq when cfq_quantum/2 2556 * requests have been dispatched. But we can drive 2557 * deeper queue depths at the beginning of slice 2558 * subjected to upper limit of cfq_quantum. 2559 * */ 2560 max_dispatch = cfqd->cfq_quantum; 2561 } 2562 2563 /* 2564 * Async queues must wait a bit before being allowed dispatch. 2565 * We also ramp up the dispatch depth gradually for async IO, 2566 * based on the last sync IO we serviced 2567 */ 2568 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2569 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2570 unsigned int depth; 2571 2572 depth = last_sync / cfqd->cfq_slice[1]; 2573 if (!depth && !cfqq->dispatched) 2574 depth = 1; 2575 if (depth < max_dispatch) 2576 max_dispatch = depth; 2577 } 2578 2579 /* 2580 * If we're below the current max, allow a dispatch 2581 */ 2582 return cfqq->dispatched < max_dispatch; 2583} 2584 2585/* 2586 * Dispatch a request from cfqq, moving them to the request queue 2587 * dispatch list. 2588 */ 2589static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2590{ 2591 struct request *rq; 2592 2593 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2594 2595 if (!cfq_may_dispatch(cfqd, cfqq)) 2596 return false; 2597 2598 /* 2599 * follow expired path, else get first next available 2600 */ 2601 rq = cfq_check_fifo(cfqq); 2602 if (!rq) 2603 rq = cfqq->next_rq; 2604 2605 /* 2606 * insert request into driver dispatch list 2607 */ 2608 cfq_dispatch_insert(cfqd->queue, rq); 2609 2610 if (!cfqd->active_cic) { 2611 struct cfq_io_cq *cic = RQ_CIC(rq); 2612 2613 atomic_long_inc(&cic->icq.ioc->refcount); 2614 cfqd->active_cic = cic; 2615 } 2616 2617 return true; 2618} 2619 2620/* 2621 * Find the cfqq that we need to service and move a request from that to the 2622 * dispatch list 2623 */ 2624static int cfq_dispatch_requests(struct request_queue *q, int force) 2625{ 2626 struct cfq_data *cfqd = q->elevator->elevator_data; 2627 struct cfq_queue *cfqq; 2628 2629 if (!cfqd->busy_queues) 2630 return 0; 2631 2632 if (unlikely(force)) 2633 return cfq_forced_dispatch(cfqd); 2634 2635 cfqq = cfq_select_queue(cfqd); 2636 if (!cfqq) 2637 return 0; 2638 2639 /* 2640 * Dispatch a request from this cfqq, if it is allowed 2641 */ 2642 if (!cfq_dispatch_request(cfqd, cfqq)) 2643 return 0; 2644 2645 cfqq->slice_dispatch++; 2646 cfq_clear_cfqq_must_dispatch(cfqq); 2647 2648 /* 2649 * expire an async queue immediately if it has used up its slice. idle 2650 * queue always expire after 1 dispatch round. 2651 */ 2652 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2653 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2654 cfq_class_idle(cfqq))) { 2655 cfqq->slice_end = jiffies + 1; 2656 cfq_slice_expired(cfqd, 0); 2657 } 2658 2659 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2660 return 1; 2661} 2662 2663/* 2664 * task holds one reference to the queue, dropped when task exits. each rq 2665 * in-flight on this queue also holds a reference, dropped when rq is freed. 2666 * 2667 * Each cfq queue took a reference on the parent group. Drop it now. 2668 * queue lock must be held here. 2669 */ 2670static void cfq_put_queue(struct cfq_queue *cfqq) 2671{ 2672 struct cfq_data *cfqd = cfqq->cfqd; 2673 struct cfq_group *cfqg; 2674 2675 BUG_ON(cfqq->ref <= 0); 2676 2677 cfqq->ref--; 2678 if (cfqq->ref) 2679 return; 2680 2681 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2682 BUG_ON(rb_first(&cfqq->sort_list)); 2683 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2684 cfqg = cfqq->cfqg; 2685 2686 if (unlikely(cfqd->active_queue == cfqq)) { 2687 __cfq_slice_expired(cfqd, cfqq, 0); 2688 cfq_schedule_dispatch(cfqd); 2689 } 2690 2691 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2692 kmem_cache_free(cfq_pool, cfqq); 2693 cfq_put_cfqg(cfqg); 2694} 2695 2696static void cfq_put_cooperator(struct cfq_queue *cfqq) 2697{ 2698 struct cfq_queue *__cfqq, *next; 2699 2700 /* 2701 * If this queue was scheduled to merge with another queue, be 2702 * sure to drop the reference taken on that queue (and others in 2703 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2704 */ 2705 __cfqq = cfqq->new_cfqq; 2706 while (__cfqq) { 2707 if (__cfqq == cfqq) { 2708 WARN(1, "cfqq->new_cfqq loop detected\n"); 2709 break; 2710 } 2711 next = __cfqq->new_cfqq; 2712 cfq_put_queue(__cfqq); 2713 __cfqq = next; 2714 } 2715} 2716 2717static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2718{ 2719 if (unlikely(cfqq == cfqd->active_queue)) { 2720 __cfq_slice_expired(cfqd, cfqq, 0); 2721 cfq_schedule_dispatch(cfqd); 2722 } 2723 2724 cfq_put_cooperator(cfqq); 2725 2726 cfq_put_queue(cfqq); 2727} 2728 2729static void cfq_init_icq(struct io_cq *icq) 2730{ 2731 struct cfq_io_cq *cic = icq_to_cic(icq); 2732 2733 cic->ttime.last_end_request = jiffies; 2734} 2735 2736static void cfq_exit_icq(struct io_cq *icq) 2737{ 2738 struct cfq_io_cq *cic = icq_to_cic(icq); 2739 struct cfq_data *cfqd = cic_to_cfqd(cic); 2740 2741 if (cic->cfqq[BLK_RW_ASYNC]) { 2742 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2743 cic->cfqq[BLK_RW_ASYNC] = NULL; 2744 } 2745 2746 if (cic->cfqq[BLK_RW_SYNC]) { 2747 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2748 cic->cfqq[BLK_RW_SYNC] = NULL; 2749 } 2750} 2751 2752static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2753{ 2754 struct task_struct *tsk = current; 2755 int ioprio_class; 2756 2757 if (!cfq_cfqq_prio_changed(cfqq)) 2758 return; 2759 2760 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2761 switch (ioprio_class) { 2762 default: 2763 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2764 case IOPRIO_CLASS_NONE: 2765 /* 2766 * no prio set, inherit CPU scheduling settings 2767 */ 2768 cfqq->ioprio = task_nice_ioprio(tsk); 2769 cfqq->ioprio_class = task_nice_ioclass(tsk); 2770 break; 2771 case IOPRIO_CLASS_RT: 2772 cfqq->ioprio = task_ioprio(ioc); 2773 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2774 break; 2775 case IOPRIO_CLASS_BE: 2776 cfqq->ioprio = task_ioprio(ioc); 2777 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2778 break; 2779 case IOPRIO_CLASS_IDLE: 2780 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2781 cfqq->ioprio = 7; 2782 cfq_clear_cfqq_idle_window(cfqq); 2783 break; 2784 } 2785 2786 /* 2787 * keep track of original prio settings in case we have to temporarily 2788 * elevate the priority of this queue 2789 */ 2790 cfqq->org_ioprio = cfqq->ioprio; 2791 cfq_clear_cfqq_prio_changed(cfqq); 2792} 2793 2794static void changed_ioprio(struct cfq_io_cq *cic) 2795{ 2796 struct cfq_data *cfqd = cic_to_cfqd(cic); 2797 struct cfq_queue *cfqq; 2798 2799 if (unlikely(!cfqd)) 2800 return; 2801 2802 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2803 if (cfqq) { 2804 struct cfq_queue *new_cfqq; 2805 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc, 2806 GFP_ATOMIC); 2807 if (new_cfqq) { 2808 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2809 cfq_put_queue(cfqq); 2810 } 2811 } 2812 2813 cfqq = cic->cfqq[BLK_RW_SYNC]; 2814 if (cfqq) 2815 cfq_mark_cfqq_prio_changed(cfqq); 2816} 2817 2818static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2819 pid_t pid, bool is_sync) 2820{ 2821 RB_CLEAR_NODE(&cfqq->rb_node); 2822 RB_CLEAR_NODE(&cfqq->p_node); 2823 INIT_LIST_HEAD(&cfqq->fifo); 2824 2825 cfqq->ref = 0; 2826 cfqq->cfqd = cfqd; 2827 2828 cfq_mark_cfqq_prio_changed(cfqq); 2829 2830 if (is_sync) { 2831 if (!cfq_class_idle(cfqq)) 2832 cfq_mark_cfqq_idle_window(cfqq); 2833 cfq_mark_cfqq_sync(cfqq); 2834 } 2835 cfqq->pid = pid; 2836} 2837 2838#ifdef CONFIG_CFQ_GROUP_IOSCHED 2839static void changed_cgroup(struct cfq_io_cq *cic) 2840{ 2841 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2842 struct cfq_data *cfqd = cic_to_cfqd(cic); 2843 struct request_queue *q; 2844 2845 if (unlikely(!cfqd)) 2846 return; 2847 2848 q = cfqd->queue; 2849 2850 if (sync_cfqq) { 2851 /* 2852 * Drop reference to sync queue. A new sync queue will be 2853 * assigned in new group upon arrival of a fresh request. 2854 */ 2855 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2856 cic_set_cfqq(cic, NULL, 1); 2857 cfq_put_queue(sync_cfqq); 2858 } 2859} 2860#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2861 2862static struct cfq_queue * 2863cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2864 struct io_context *ioc, gfp_t gfp_mask) 2865{ 2866 struct blkio_cgroup *blkcg; 2867 struct cfq_queue *cfqq, *new_cfqq = NULL; 2868 struct cfq_io_cq *cic; 2869 struct cfq_group *cfqg; 2870 2871retry: 2872 rcu_read_lock(); 2873 2874 blkcg = task_blkio_cgroup(current); 2875 2876 cfqg = cfq_get_cfqg(cfqd, blkcg); 2877 cic = cfq_cic_lookup(cfqd, ioc); 2878 /* cic always exists here */ 2879 cfqq = cic_to_cfqq(cic, is_sync); 2880 2881 /* 2882 * Always try a new alloc if we fell back to the OOM cfqq 2883 * originally, since it should just be a temporary situation. 2884 */ 2885 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 2886 cfqq = NULL; 2887 if (new_cfqq) { 2888 cfqq = new_cfqq; 2889 new_cfqq = NULL; 2890 } else if (gfp_mask & __GFP_WAIT) { 2891 rcu_read_unlock(); 2892 spin_unlock_irq(cfqd->queue->queue_lock); 2893 new_cfqq = kmem_cache_alloc_node(cfq_pool, 2894 gfp_mask | __GFP_ZERO, 2895 cfqd->queue->node); 2896 spin_lock_irq(cfqd->queue->queue_lock); 2897 if (new_cfqq) 2898 goto retry; 2899 } else { 2900 cfqq = kmem_cache_alloc_node(cfq_pool, 2901 gfp_mask | __GFP_ZERO, 2902 cfqd->queue->node); 2903 } 2904 2905 if (cfqq) { 2906 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 2907 cfq_init_prio_data(cfqq, ioc); 2908 cfq_link_cfqq_cfqg(cfqq, cfqg); 2909 cfq_log_cfqq(cfqd, cfqq, "alloced"); 2910 } else 2911 cfqq = &cfqd->oom_cfqq; 2912 } 2913 2914 if (new_cfqq) 2915 kmem_cache_free(cfq_pool, new_cfqq); 2916 2917 rcu_read_unlock(); 2918 return cfqq; 2919} 2920 2921static struct cfq_queue ** 2922cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 2923{ 2924 switch (ioprio_class) { 2925 case IOPRIO_CLASS_RT: 2926 return &cfqd->async_cfqq[0][ioprio]; 2927 case IOPRIO_CLASS_BE: 2928 return &cfqd->async_cfqq[1][ioprio]; 2929 case IOPRIO_CLASS_IDLE: 2930 return &cfqd->async_idle_cfqq; 2931 default: 2932 BUG(); 2933 } 2934} 2935 2936static struct cfq_queue * 2937cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 2938 gfp_t gfp_mask) 2939{ 2940 const int ioprio = task_ioprio(ioc); 2941 const int ioprio_class = task_ioprio_class(ioc); 2942 struct cfq_queue **async_cfqq = NULL; 2943 struct cfq_queue *cfqq = NULL; 2944 2945 if (!is_sync) { 2946 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 2947 cfqq = *async_cfqq; 2948 } 2949 2950 if (!cfqq) 2951 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 2952 2953 /* 2954 * pin the queue now that it's allocated, scheduler exit will prune it 2955 */ 2956 if (!is_sync && !(*async_cfqq)) { 2957 cfqq->ref++; 2958 *async_cfqq = cfqq; 2959 } 2960 2961 cfqq->ref++; 2962 return cfqq; 2963} 2964 2965static void 2966__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) 2967{ 2968 unsigned long elapsed = jiffies - ttime->last_end_request; 2969 elapsed = min(elapsed, 2UL * slice_idle); 2970 2971 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; 2972 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; 2973 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; 2974} 2975 2976static void 2977cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2978 struct cfq_io_cq *cic) 2979{ 2980 if (cfq_cfqq_sync(cfqq)) { 2981 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); 2982 __cfq_update_io_thinktime(&cfqq->service_tree->ttime, 2983 cfqd->cfq_slice_idle); 2984 } 2985#ifdef CONFIG_CFQ_GROUP_IOSCHED 2986 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); 2987#endif 2988} 2989 2990static void 2991cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2992 struct request *rq) 2993{ 2994 sector_t sdist = 0; 2995 sector_t n_sec = blk_rq_sectors(rq); 2996 if (cfqq->last_request_pos) { 2997 if (cfqq->last_request_pos < blk_rq_pos(rq)) 2998 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 2999 else 3000 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3001 } 3002 3003 cfqq->seek_history <<= 1; 3004 if (blk_queue_nonrot(cfqd->queue)) 3005 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3006 else 3007 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3008} 3009 3010/* 3011 * Disable idle window if the process thinks too long or seeks so much that 3012 * it doesn't matter 3013 */ 3014static void 3015cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3016 struct cfq_io_cq *cic) 3017{ 3018 int old_idle, enable_idle; 3019 3020 /* 3021 * Don't idle for async or idle io prio class 3022 */ 3023 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3024 return; 3025 3026 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3027 3028 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3029 cfq_mark_cfqq_deep(cfqq); 3030 3031 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3032 enable_idle = 0; 3033 else if (!atomic_read(&cic->icq.ioc->nr_tasks) || 3034 !cfqd->cfq_slice_idle || 3035 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3036 enable_idle = 0; 3037 else if (sample_valid(cic->ttime.ttime_samples)) { 3038 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) 3039 enable_idle = 0; 3040 else 3041 enable_idle = 1; 3042 } 3043 3044 if (old_idle != enable_idle) { 3045 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3046 if (enable_idle) 3047 cfq_mark_cfqq_idle_window(cfqq); 3048 else 3049 cfq_clear_cfqq_idle_window(cfqq); 3050 } 3051} 3052 3053/* 3054 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3055 * no or if we aren't sure, a 1 will cause a preempt. 3056 */ 3057static bool 3058cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3059 struct request *rq) 3060{ 3061 struct cfq_queue *cfqq; 3062 3063 cfqq = cfqd->active_queue; 3064 if (!cfqq) 3065 return false; 3066 3067 if (cfq_class_idle(new_cfqq)) 3068 return false; 3069 3070 if (cfq_class_idle(cfqq)) 3071 return true; 3072 3073 /* 3074 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3075 */ 3076 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3077 return false; 3078 3079 /* 3080 * if the new request is sync, but the currently running queue is 3081 * not, let the sync request have priority. 3082 */ 3083 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3084 return true; 3085 3086 if (new_cfqq->cfqg != cfqq->cfqg) 3087 return false; 3088 3089 if (cfq_slice_used(cfqq)) 3090 return true; 3091 3092 /* Allow preemption only if we are idling on sync-noidle tree */ 3093 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3094 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3095 new_cfqq->service_tree->count == 2 && 3096 RB_EMPTY_ROOT(&cfqq->sort_list)) 3097 return true; 3098 3099 /* 3100 * So both queues are sync. Let the new request get disk time if 3101 * it's a metadata request and the current queue is doing regular IO. 3102 */ 3103 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) 3104 return true; 3105 3106 /* 3107 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3108 */ 3109 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3110 return true; 3111 3112 /* An idle queue should not be idle now for some reason */ 3113 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3114 return true; 3115 3116 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3117 return false; 3118 3119 /* 3120 * if this request is as-good as one we would expect from the 3121 * current cfqq, let it preempt 3122 */ 3123 if (cfq_rq_close(cfqd, cfqq, rq)) 3124 return true; 3125 3126 return false; 3127} 3128 3129/* 3130 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3131 * let it have half of its nominal slice. 3132 */ 3133static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3134{ 3135 enum wl_type_t old_type = cfqq_type(cfqd->active_queue); 3136 3137 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3138 cfq_slice_expired(cfqd, 1); 3139 3140 /* 3141 * workload type is changed, don't save slice, otherwise preempt 3142 * doesn't happen 3143 */ 3144 if (old_type != cfqq_type(cfqq)) 3145 cfqq->cfqg->saved_workload_slice = 0; 3146 3147 /* 3148 * Put the new queue at the front of the of the current list, 3149 * so we know that it will be selected next. 3150 */ 3151 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3152 3153 cfq_service_tree_add(cfqd, cfqq, 1); 3154 3155 cfqq->slice_end = 0; 3156 cfq_mark_cfqq_slice_new(cfqq); 3157} 3158 3159/* 3160 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3161 * something we should do about it 3162 */ 3163static void 3164cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3165 struct request *rq) 3166{ 3167 struct cfq_io_cq *cic = RQ_CIC(rq); 3168 3169 cfqd->rq_queued++; 3170 if (rq->cmd_flags & REQ_PRIO) 3171 cfqq->prio_pending++; 3172 3173 cfq_update_io_thinktime(cfqd, cfqq, cic); 3174 cfq_update_io_seektime(cfqd, cfqq, rq); 3175 cfq_update_idle_window(cfqd, cfqq, cic); 3176 3177 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3178 3179 if (cfqq == cfqd->active_queue) { 3180 /* 3181 * Remember that we saw a request from this process, but 3182 * don't start queuing just yet. Otherwise we risk seeing lots 3183 * of tiny requests, because we disrupt the normal plugging 3184 * and merging. If the request is already larger than a single 3185 * page, let it rip immediately. For that case we assume that 3186 * merging is already done. Ditto for a busy system that 3187 * has other work pending, don't risk delaying until the 3188 * idle timer unplug to continue working. 3189 */ 3190 if (cfq_cfqq_wait_request(cfqq)) { 3191 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3192 cfqd->busy_queues > 1) { 3193 cfq_del_timer(cfqd, cfqq); 3194 cfq_clear_cfqq_wait_request(cfqq); 3195 __blk_run_queue(cfqd->queue); 3196 } else { 3197 cfq_blkiocg_update_idle_time_stats( 3198 &cfqq->cfqg->blkg); 3199 cfq_mark_cfqq_must_dispatch(cfqq); 3200 } 3201 } 3202 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3203 /* 3204 * not the active queue - expire current slice if it is 3205 * idle and has expired it's mean thinktime or this new queue 3206 * has some old slice time left and is of higher priority or 3207 * this new queue is RT and the current one is BE 3208 */ 3209 cfq_preempt_queue(cfqd, cfqq); 3210 __blk_run_queue(cfqd->queue); 3211 } 3212} 3213 3214static void cfq_insert_request(struct request_queue *q, struct request *rq) 3215{ 3216 struct cfq_data *cfqd = q->elevator->elevator_data; 3217 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3218 3219 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3220 cfq_init_prio_data(cfqq, RQ_CIC(rq)->icq.ioc); 3221 3222 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3223 list_add_tail(&rq->queuelist, &cfqq->fifo); 3224 cfq_add_rq_rb(rq); 3225 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 3226 &cfqd->serving_group->blkg, rq_data_dir(rq), 3227 rq_is_sync(rq)); 3228 cfq_rq_enqueued(cfqd, cfqq, rq); 3229} 3230 3231/* 3232 * Update hw_tag based on peak queue depth over 50 samples under 3233 * sufficient load. 3234 */ 3235static void cfq_update_hw_tag(struct cfq_data *cfqd) 3236{ 3237 struct cfq_queue *cfqq = cfqd->active_queue; 3238 3239 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3240 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3241 3242 if (cfqd->hw_tag == 1) 3243 return; 3244 3245 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3246 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3247 return; 3248 3249 /* 3250 * If active queue hasn't enough requests and can idle, cfq might not 3251 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3252 * case 3253 */ 3254 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3255 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3256 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3257 return; 3258 3259 if (cfqd->hw_tag_samples++ < 50) 3260 return; 3261 3262 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3263 cfqd->hw_tag = 1; 3264 else 3265 cfqd->hw_tag = 0; 3266} 3267 3268static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3269{ 3270 struct cfq_io_cq *cic = cfqd->active_cic; 3271 3272 /* If the queue already has requests, don't wait */ 3273 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3274 return false; 3275 3276 /* If there are other queues in the group, don't wait */ 3277 if (cfqq->cfqg->nr_cfqq > 1) 3278 return false; 3279 3280 /* the only queue in the group, but think time is big */ 3281 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) 3282 return false; 3283 3284 if (cfq_slice_used(cfqq)) 3285 return true; 3286 3287 /* if slice left is less than think time, wait busy */ 3288 if (cic && sample_valid(cic->ttime.ttime_samples) 3289 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) 3290 return true; 3291 3292 /* 3293 * If think times is less than a jiffy than ttime_mean=0 and above 3294 * will not be true. It might happen that slice has not expired yet 3295 * but will expire soon (4-5 ns) during select_queue(). To cover the 3296 * case where think time is less than a jiffy, mark the queue wait 3297 * busy if only 1 jiffy is left in the slice. 3298 */ 3299 if (cfqq->slice_end - jiffies == 1) 3300 return true; 3301 3302 return false; 3303} 3304 3305static void cfq_completed_request(struct request_queue *q, struct request *rq) 3306{ 3307 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3308 struct cfq_data *cfqd = cfqq->cfqd; 3309 const int sync = rq_is_sync(rq); 3310 unsigned long now; 3311 3312 now = jiffies; 3313 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3314 !!(rq->cmd_flags & REQ_NOIDLE)); 3315 3316 cfq_update_hw_tag(cfqd); 3317 3318 WARN_ON(!cfqd->rq_in_driver); 3319 WARN_ON(!cfqq->dispatched); 3320 cfqd->rq_in_driver--; 3321 cfqq->dispatched--; 3322 (RQ_CFQG(rq))->dispatched--; 3323 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, 3324 rq_start_time_ns(rq), rq_io_start_time_ns(rq), 3325 rq_data_dir(rq), rq_is_sync(rq)); 3326 3327 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3328 3329 if (sync) { 3330 struct cfq_rb_root *service_tree; 3331 3332 RQ_CIC(rq)->ttime.last_end_request = now; 3333 3334 if (cfq_cfqq_on_rr(cfqq)) 3335 service_tree = cfqq->service_tree; 3336 else 3337 service_tree = service_tree_for(cfqq->cfqg, 3338 cfqq_prio(cfqq), cfqq_type(cfqq)); 3339 service_tree->ttime.last_end_request = now; 3340 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3341 cfqd->last_delayed_sync = now; 3342 } 3343 3344#ifdef CONFIG_CFQ_GROUP_IOSCHED 3345 cfqq->cfqg->ttime.last_end_request = now; 3346#endif 3347 3348 /* 3349 * If this is the active queue, check if it needs to be expired, 3350 * or if we want to idle in case it has no pending requests. 3351 */ 3352 if (cfqd->active_queue == cfqq) { 3353 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3354 3355 if (cfq_cfqq_slice_new(cfqq)) { 3356 cfq_set_prio_slice(cfqd, cfqq); 3357 cfq_clear_cfqq_slice_new(cfqq); 3358 } 3359 3360 /* 3361 * Should we wait for next request to come in before we expire 3362 * the queue. 3363 */ 3364 if (cfq_should_wait_busy(cfqd, cfqq)) { 3365 unsigned long extend_sl = cfqd->cfq_slice_idle; 3366 if (!cfqd->cfq_slice_idle) 3367 extend_sl = cfqd->cfq_group_idle; 3368 cfqq->slice_end = jiffies + extend_sl; 3369 cfq_mark_cfqq_wait_busy(cfqq); 3370 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3371 } 3372 3373 /* 3374 * Idling is not enabled on: 3375 * - expired queues 3376 * - idle-priority queues 3377 * - async queues 3378 * - queues with still some requests queued 3379 * - when there is a close cooperator 3380 */ 3381 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3382 cfq_slice_expired(cfqd, 1); 3383 else if (sync && cfqq_empty && 3384 !cfq_close_cooperator(cfqd, cfqq)) { 3385 cfq_arm_slice_timer(cfqd); 3386 } 3387 } 3388 3389 if (!cfqd->rq_in_driver) 3390 cfq_schedule_dispatch(cfqd); 3391} 3392 3393static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3394{ 3395 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3396 cfq_mark_cfqq_must_alloc_slice(cfqq); 3397 return ELV_MQUEUE_MUST; 3398 } 3399 3400 return ELV_MQUEUE_MAY; 3401} 3402 3403static int cfq_may_queue(struct request_queue *q, int rw) 3404{ 3405 struct cfq_data *cfqd = q->elevator->elevator_data; 3406 struct task_struct *tsk = current; 3407 struct cfq_io_cq *cic; 3408 struct cfq_queue *cfqq; 3409 3410 /* 3411 * don't force setup of a queue from here, as a call to may_queue 3412 * does not necessarily imply that a request actually will be queued. 3413 * so just lookup a possibly existing queue, or return 'may queue' 3414 * if that fails 3415 */ 3416 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3417 if (!cic) 3418 return ELV_MQUEUE_MAY; 3419 3420 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3421 if (cfqq) { 3422 cfq_init_prio_data(cfqq, cic->icq.ioc); 3423 3424 return __cfq_may_queue(cfqq); 3425 } 3426 3427 return ELV_MQUEUE_MAY; 3428} 3429 3430/* 3431 * queue lock held here 3432 */ 3433static void cfq_put_request(struct request *rq) 3434{ 3435 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3436 3437 if (cfqq) { 3438 const int rw = rq_data_dir(rq); 3439 3440 BUG_ON(!cfqq->allocated[rw]); 3441 cfqq->allocated[rw]--; 3442 3443 /* Put down rq reference on cfqg */ 3444 cfq_put_cfqg(RQ_CFQG(rq)); 3445 rq->elv.priv[0] = NULL; 3446 rq->elv.priv[1] = NULL; 3447 3448 cfq_put_queue(cfqq); 3449 } 3450} 3451 3452static struct cfq_queue * 3453cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic, 3454 struct cfq_queue *cfqq) 3455{ 3456 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3457 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3458 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3459 cfq_put_queue(cfqq); 3460 return cic_to_cfqq(cic, 1); 3461} 3462 3463/* 3464 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3465 * was the last process referring to said cfqq. 3466 */ 3467static struct cfq_queue * 3468split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq) 3469{ 3470 if (cfqq_process_refs(cfqq) == 1) { 3471 cfqq->pid = current->pid; 3472 cfq_clear_cfqq_coop(cfqq); 3473 cfq_clear_cfqq_split_coop(cfqq); 3474 return cfqq; 3475 } 3476 3477 cic_set_cfqq(cic, NULL, 1); 3478 3479 cfq_put_cooperator(cfqq); 3480 3481 cfq_put_queue(cfqq); 3482 return NULL; 3483} 3484/* 3485 * Allocate cfq data structures associated with this request. 3486 */ 3487static int 3488cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3489{ 3490 struct cfq_data *cfqd = q->elevator->elevator_data; 3491 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq); 3492 const int rw = rq_data_dir(rq); 3493 const bool is_sync = rq_is_sync(rq); 3494 struct cfq_queue *cfqq; 3495 unsigned int changed; 3496 3497 might_sleep_if(gfp_mask & __GFP_WAIT); 3498 3499 spin_lock_irq(q->queue_lock); 3500 3501 /* handle changed notifications */ 3502 changed = icq_get_changed(&cic->icq); 3503 if (unlikely(changed & ICQ_IOPRIO_CHANGED)) 3504 changed_ioprio(cic); 3505#ifdef CONFIG_CFQ_GROUP_IOSCHED 3506 if (unlikely(changed & ICQ_CGROUP_CHANGED)) 3507 changed_cgroup(cic); 3508#endif 3509 3510new_queue: 3511 cfqq = cic_to_cfqq(cic, is_sync); 3512 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3513 cfqq = cfq_get_queue(cfqd, is_sync, cic->icq.ioc, gfp_mask); 3514 cic_set_cfqq(cic, cfqq, is_sync); 3515 } else { 3516 /* 3517 * If the queue was seeky for too long, break it apart. 3518 */ 3519 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3520 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3521 cfqq = split_cfqq(cic, cfqq); 3522 if (!cfqq) 3523 goto new_queue; 3524 } 3525 3526 /* 3527 * Check to see if this queue is scheduled to merge with 3528 * another, closely cooperating queue. The merging of 3529 * queues happens here as it must be done in process context. 3530 * The reference on new_cfqq was taken in merge_cfqqs. 3531 */ 3532 if (cfqq->new_cfqq) 3533 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3534 } 3535 3536 cfqq->allocated[rw]++; 3537 3538 cfqq->ref++; 3539 rq->elv.priv[0] = cfqq; 3540 rq->elv.priv[1] = cfq_ref_get_cfqg(cfqq->cfqg); 3541 spin_unlock_irq(q->queue_lock); 3542 return 0; 3543} 3544 3545static void cfq_kick_queue(struct work_struct *work) 3546{ 3547 struct cfq_data *cfqd = 3548 container_of(work, struct cfq_data, unplug_work); 3549 struct request_queue *q = cfqd->queue; 3550 3551 spin_lock_irq(q->queue_lock); 3552 __blk_run_queue(cfqd->queue); 3553 spin_unlock_irq(q->queue_lock); 3554} 3555 3556/* 3557 * Timer running if the active_queue is currently idling inside its time slice 3558 */ 3559static void cfq_idle_slice_timer(unsigned long data) 3560{ 3561 struct cfq_data *cfqd = (struct cfq_data *) data; 3562 struct cfq_queue *cfqq; 3563 unsigned long flags; 3564 int timed_out = 1; 3565 3566 cfq_log(cfqd, "idle timer fired"); 3567 3568 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3569 3570 cfqq = cfqd->active_queue; 3571 if (cfqq) { 3572 timed_out = 0; 3573 3574 /* 3575 * We saw a request before the queue expired, let it through 3576 */ 3577 if (cfq_cfqq_must_dispatch(cfqq)) 3578 goto out_kick; 3579 3580 /* 3581 * expired 3582 */ 3583 if (cfq_slice_used(cfqq)) 3584 goto expire; 3585 3586 /* 3587 * only expire and reinvoke request handler, if there are 3588 * other queues with pending requests 3589 */ 3590 if (!cfqd->busy_queues) 3591 goto out_cont; 3592 3593 /* 3594 * not expired and it has a request pending, let it dispatch 3595 */ 3596 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3597 goto out_kick; 3598 3599 /* 3600 * Queue depth flag is reset only when the idle didn't succeed 3601 */ 3602 cfq_clear_cfqq_deep(cfqq); 3603 } 3604expire: 3605 cfq_slice_expired(cfqd, timed_out); 3606out_kick: 3607 cfq_schedule_dispatch(cfqd); 3608out_cont: 3609 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3610} 3611 3612static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3613{ 3614 del_timer_sync(&cfqd->idle_slice_timer); 3615 cancel_work_sync(&cfqd->unplug_work); 3616} 3617 3618static void cfq_put_async_queues(struct cfq_data *cfqd) 3619{ 3620 int i; 3621 3622 for (i = 0; i < IOPRIO_BE_NR; i++) { 3623 if (cfqd->async_cfqq[0][i]) 3624 cfq_put_queue(cfqd->async_cfqq[0][i]); 3625 if (cfqd->async_cfqq[1][i]) 3626 cfq_put_queue(cfqd->async_cfqq[1][i]); 3627 } 3628 3629 if (cfqd->async_idle_cfqq) 3630 cfq_put_queue(cfqd->async_idle_cfqq); 3631} 3632 3633static void cfq_exit_queue(struct elevator_queue *e) 3634{ 3635 struct cfq_data *cfqd = e->elevator_data; 3636 struct request_queue *q = cfqd->queue; 3637 bool wait = false; 3638 3639 cfq_shutdown_timer_wq(cfqd); 3640 3641 spin_lock_irq(q->queue_lock); 3642 3643 if (cfqd->active_queue) 3644 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3645 3646 cfq_put_async_queues(cfqd); 3647 cfq_release_cfq_groups(cfqd); 3648 3649 /* 3650 * If there are groups which we could not unlink from blkcg list, 3651 * wait for a rcu period for them to be freed. 3652 */ 3653 if (cfqd->nr_blkcg_linked_grps) 3654 wait = true; 3655 3656 spin_unlock_irq(q->queue_lock); 3657 3658 cfq_shutdown_timer_wq(cfqd); 3659 3660 /* 3661 * Wait for cfqg->blkg->key accessors to exit their grace periods. 3662 * Do this wait only if there are other unlinked groups out 3663 * there. This can happen if cgroup deletion path claimed the 3664 * responsibility of cleaning up a group before queue cleanup code 3665 * get to the group. 3666 * 3667 * Do not call synchronize_rcu() unconditionally as there are drivers 3668 * which create/delete request queue hundreds of times during scan/boot 3669 * and synchronize_rcu() can take significant time and slow down boot. 3670 */ 3671 if (wait) 3672 synchronize_rcu(); 3673 3674#ifdef CONFIG_CFQ_GROUP_IOSCHED 3675 /* Free up per cpu stats for root group */ 3676 free_percpu(cfqd->root_group.blkg.stats_cpu); 3677#endif 3678 kfree(cfqd); 3679} 3680 3681static int cfq_init_queue(struct request_queue *q) 3682{ 3683 struct cfq_data *cfqd; 3684 int i, j; 3685 struct cfq_group *cfqg; 3686 struct cfq_rb_root *st; 3687 3688 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3689 if (!cfqd) 3690 return -ENOMEM; 3691 3692 /* Init root service tree */ 3693 cfqd->grp_service_tree = CFQ_RB_ROOT; 3694 3695 /* Init root group */ 3696 cfqg = &cfqd->root_group; 3697 for_each_cfqg_st(cfqg, i, j, st) 3698 *st = CFQ_RB_ROOT; 3699 RB_CLEAR_NODE(&cfqg->rb_node); 3700 3701 /* Give preference to root group over other groups */ 3702 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 3703 3704#ifdef CONFIG_CFQ_GROUP_IOSCHED 3705 /* 3706 * Set root group reference to 2. One reference will be dropped when 3707 * all groups on cfqd->cfqg_list are being deleted during queue exit. 3708 * Other reference will remain there as we don't want to delete this 3709 * group as it is statically allocated and gets destroyed when 3710 * throtl_data goes away. 3711 */ 3712 cfqg->ref = 2; 3713 3714 if (blkio_alloc_blkg_stats(&cfqg->blkg)) { 3715 kfree(cfqg); 3716 kfree(cfqd); 3717 return -ENOMEM; 3718 } 3719 3720 rcu_read_lock(); 3721 3722 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, 3723 cfqd->queue, 0); 3724 rcu_read_unlock(); 3725 cfqd->nr_blkcg_linked_grps++; 3726 3727 /* Add group on cfqd->cfqg_list */ 3728 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 3729#endif 3730 /* 3731 * Not strictly needed (since RB_ROOT just clears the node and we 3732 * zeroed cfqd on alloc), but better be safe in case someone decides 3733 * to add magic to the rb code 3734 */ 3735 for (i = 0; i < CFQ_PRIO_LISTS; i++) 3736 cfqd->prio_trees[i] = RB_ROOT; 3737 3738 /* 3739 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 3740 * Grab a permanent reference to it, so that the normal code flow 3741 * will not attempt to free it. 3742 */ 3743 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 3744 cfqd->oom_cfqq.ref++; 3745 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 3746 3747 cfqd->queue = q; 3748 q->elevator->elevator_data = cfqd; 3749 3750 init_timer(&cfqd->idle_slice_timer); 3751 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 3752 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 3753 3754 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 3755 3756 cfqd->cfq_quantum = cfq_quantum; 3757 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 3758 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 3759 cfqd->cfq_back_max = cfq_back_max; 3760 cfqd->cfq_back_penalty = cfq_back_penalty; 3761 cfqd->cfq_slice[0] = cfq_slice_async; 3762 cfqd->cfq_slice[1] = cfq_slice_sync; 3763 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 3764 cfqd->cfq_slice_idle = cfq_slice_idle; 3765 cfqd->cfq_group_idle = cfq_group_idle; 3766 cfqd->cfq_latency = 1; 3767 cfqd->hw_tag = -1; 3768 /* 3769 * we optimistically start assuming sync ops weren't delayed in last 3770 * second, in order to have larger depth for async operations. 3771 */ 3772 cfqd->last_delayed_sync = jiffies - HZ; 3773 return 0; 3774} 3775 3776/* 3777 * sysfs parts below --> 3778 */ 3779static ssize_t 3780cfq_var_show(unsigned int var, char *page) 3781{ 3782 return sprintf(page, "%d\n", var); 3783} 3784 3785static ssize_t 3786cfq_var_store(unsigned int *var, const char *page, size_t count) 3787{ 3788 char *p = (char *) page; 3789 3790 *var = simple_strtoul(p, &p, 10); 3791 return count; 3792} 3793 3794#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 3795static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 3796{ \ 3797 struct cfq_data *cfqd = e->elevator_data; \ 3798 unsigned int __data = __VAR; \ 3799 if (__CONV) \ 3800 __data = jiffies_to_msecs(__data); \ 3801 return cfq_var_show(__data, (page)); \ 3802} 3803SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 3804SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 3805SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 3806SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 3807SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 3808SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 3809SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 3810SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 3811SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 3812SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 3813SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 3814#undef SHOW_FUNCTION 3815 3816#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 3817static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 3818{ \ 3819 struct cfq_data *cfqd = e->elevator_data; \ 3820 unsigned int __data; \ 3821 int ret = cfq_var_store(&__data, (page), count); \ 3822 if (__data < (MIN)) \ 3823 __data = (MIN); \ 3824 else if (__data > (MAX)) \ 3825 __data = (MAX); \ 3826 if (__CONV) \ 3827 *(__PTR) = msecs_to_jiffies(__data); \ 3828 else \ 3829 *(__PTR) = __data; \ 3830 return ret; \ 3831} 3832STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 3833STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 3834 UINT_MAX, 1); 3835STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 3836 UINT_MAX, 1); 3837STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 3838STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 3839 UINT_MAX, 0); 3840STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 3841STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 3842STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 3843STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 3844STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 3845 UINT_MAX, 0); 3846STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 3847#undef STORE_FUNCTION 3848 3849#define CFQ_ATTR(name) \ 3850 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 3851 3852static struct elv_fs_entry cfq_attrs[] = { 3853 CFQ_ATTR(quantum), 3854 CFQ_ATTR(fifo_expire_sync), 3855 CFQ_ATTR(fifo_expire_async), 3856 CFQ_ATTR(back_seek_max), 3857 CFQ_ATTR(back_seek_penalty), 3858 CFQ_ATTR(slice_sync), 3859 CFQ_ATTR(slice_async), 3860 CFQ_ATTR(slice_async_rq), 3861 CFQ_ATTR(slice_idle), 3862 CFQ_ATTR(group_idle), 3863 CFQ_ATTR(low_latency), 3864 __ATTR_NULL 3865}; 3866 3867static struct elevator_type iosched_cfq = { 3868 .ops = { 3869 .elevator_merge_fn = cfq_merge, 3870 .elevator_merged_fn = cfq_merged_request, 3871 .elevator_merge_req_fn = cfq_merged_requests, 3872 .elevator_allow_merge_fn = cfq_allow_merge, 3873 .elevator_bio_merged_fn = cfq_bio_merged, 3874 .elevator_dispatch_fn = cfq_dispatch_requests, 3875 .elevator_add_req_fn = cfq_insert_request, 3876 .elevator_activate_req_fn = cfq_activate_request, 3877 .elevator_deactivate_req_fn = cfq_deactivate_request, 3878 .elevator_completed_req_fn = cfq_completed_request, 3879 .elevator_former_req_fn = elv_rb_former_request, 3880 .elevator_latter_req_fn = elv_rb_latter_request, 3881 .elevator_init_icq_fn = cfq_init_icq, 3882 .elevator_exit_icq_fn = cfq_exit_icq, 3883 .elevator_set_req_fn = cfq_set_request, 3884 .elevator_put_req_fn = cfq_put_request, 3885 .elevator_may_queue_fn = cfq_may_queue, 3886 .elevator_init_fn = cfq_init_queue, 3887 .elevator_exit_fn = cfq_exit_queue, 3888 }, 3889 .icq_size = sizeof(struct cfq_io_cq), 3890 .icq_align = __alignof__(struct cfq_io_cq), 3891 .elevator_attrs = cfq_attrs, 3892 .elevator_name = "cfq", 3893 .elevator_owner = THIS_MODULE, 3894}; 3895 3896#ifdef CONFIG_CFQ_GROUP_IOSCHED 3897static struct blkio_policy_type blkio_policy_cfq = { 3898 .ops = { 3899 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 3900 .blkio_clear_queue_fn = cfq_clear_queue, 3901 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 3902 }, 3903 .plid = BLKIO_POLICY_PROP, 3904}; 3905#endif 3906 3907static int __init cfq_init(void) 3908{ 3909 int ret; 3910 3911 /* 3912 * could be 0 on HZ < 1000 setups 3913 */ 3914 if (!cfq_slice_async) 3915 cfq_slice_async = 1; 3916 if (!cfq_slice_idle) 3917 cfq_slice_idle = 1; 3918 3919#ifdef CONFIG_CFQ_GROUP_IOSCHED 3920 if (!cfq_group_idle) 3921 cfq_group_idle = 1; 3922#else 3923 cfq_group_idle = 0; 3924#endif 3925 cfq_pool = KMEM_CACHE(cfq_queue, 0); 3926 if (!cfq_pool) 3927 return -ENOMEM; 3928 3929 ret = elv_register(&iosched_cfq); 3930 if (ret) { 3931 kmem_cache_destroy(cfq_pool); 3932 return ret; 3933 } 3934 3935#ifdef CONFIG_CFQ_GROUP_IOSCHED 3936 blkio_policy_register(&blkio_policy_cfq); 3937#endif 3938 return 0; 3939} 3940 3941static void __exit cfq_exit(void) 3942{ 3943#ifdef CONFIG_CFQ_GROUP_IOSCHED 3944 blkio_policy_unregister(&blkio_policy_cfq); 3945#endif 3946 elv_unregister(&iosched_cfq); 3947 kmem_cache_destroy(cfq_pool); 3948} 3949 3950module_init(cfq_init); 3951module_exit(cfq_exit); 3952 3953MODULE_AUTHOR("Jens Axboe"); 3954MODULE_LICENSE("GPL"); 3955MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 3956