cfq-iosched.c revision 4aede84b33d6beb401136a3deca0651ae07c5e99
1/* 2 * CFQ, or complete fairness queueing, disk scheduler. 3 * 4 * Based on ideas from a previously unfinished io 5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. 6 * 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> 8 */ 9#include <linux/module.h> 10#include <linux/slab.h> 11#include <linux/blkdev.h> 12#include <linux/elevator.h> 13#include <linux/jiffies.h> 14#include <linux/rbtree.h> 15#include <linux/ioprio.h> 16#include <linux/blktrace_api.h> 17#include "cfq.h" 18 19/* 20 * tunables 21 */ 22/* max queue in one round of service */ 23static const int cfq_quantum = 8; 24static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 25/* maximum backwards seek, in KiB */ 26static const int cfq_back_max = 16 * 1024; 27/* penalty of a backwards seek */ 28static const int cfq_back_penalty = 2; 29static const int cfq_slice_sync = HZ / 10; 30static int cfq_slice_async = HZ / 25; 31static const int cfq_slice_async_rq = 2; 32static int cfq_slice_idle = HZ / 125; 33static int cfq_group_idle = HZ / 125; 34static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 35static const int cfq_hist_divisor = 4; 36 37/* 38 * offset from end of service tree 39 */ 40#define CFQ_IDLE_DELAY (HZ / 5) 41 42/* 43 * below this threshold, we consider thinktime immediate 44 */ 45#define CFQ_MIN_TT (2) 46 47#define CFQ_SLICE_SCALE (5) 48#define CFQ_HW_QUEUE_MIN (5) 49#define CFQ_SERVICE_SHIFT 12 50 51#define CFQQ_SEEK_THR (sector_t)(8 * 100) 52#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 53#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 54#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 55 56#define RQ_CIC(rq) \ 57 ((struct cfq_io_context *) (rq)->elevator_private[0]) 58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1]) 59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2]) 60 61static struct kmem_cache *cfq_pool; 62static struct kmem_cache *cfq_ioc_pool; 63 64static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); 65static struct completion *ioc_gone; 66static DEFINE_SPINLOCK(ioc_gone_lock); 67 68static DEFINE_SPINLOCK(cic_index_lock); 69static DEFINE_IDA(cic_index_ida); 70 71#define CFQ_PRIO_LISTS IOPRIO_BE_NR 72#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 73#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 74 75#define sample_valid(samples) ((samples) > 80) 76#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 77 78/* 79 * Most of our rbtree usage is for sorting with min extraction, so 80 * if we cache the leftmost node we don't have to walk down the tree 81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 82 * move this into the elevator for the rq sorting as well. 83 */ 84struct cfq_rb_root { 85 struct rb_root rb; 86 struct rb_node *left; 87 unsigned count; 88 unsigned total_weight; 89 u64 min_vdisktime; 90}; 91#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ 92 .count = 0, .min_vdisktime = 0, } 93 94/* 95 * Per process-grouping structure 96 */ 97struct cfq_queue { 98 /* reference count */ 99 int ref; 100 /* various state flags, see below */ 101 unsigned int flags; 102 /* parent cfq_data */ 103 struct cfq_data *cfqd; 104 /* service_tree member */ 105 struct rb_node rb_node; 106 /* service_tree key */ 107 unsigned long rb_key; 108 /* prio tree member */ 109 struct rb_node p_node; 110 /* prio tree root we belong to, if any */ 111 struct rb_root *p_root; 112 /* sorted list of pending requests */ 113 struct rb_root sort_list; 114 /* if fifo isn't expired, next request to serve */ 115 struct request *next_rq; 116 /* requests queued in sort_list */ 117 int queued[2]; 118 /* currently allocated requests */ 119 int allocated[2]; 120 /* fifo list of requests in sort_list */ 121 struct list_head fifo; 122 123 /* time when queue got scheduled in to dispatch first request. */ 124 unsigned long dispatch_start; 125 unsigned int allocated_slice; 126 unsigned int slice_dispatch; 127 /* time when first request from queue completed and slice started. */ 128 unsigned long slice_start; 129 unsigned long slice_end; 130 long slice_resid; 131 132 /* number of requests that are on the dispatch list or inside driver */ 133 int dispatched; 134 135 /* io prio of this group */ 136 unsigned short ioprio, org_ioprio; 137 unsigned short ioprio_class; 138 139 pid_t pid; 140 141 u32 seek_history; 142 sector_t last_request_pos; 143 144 struct cfq_rb_root *service_tree; 145 struct cfq_queue *new_cfqq; 146 struct cfq_group *cfqg; 147 /* Number of sectors dispatched from queue in single dispatch round */ 148 unsigned long nr_sectors; 149}; 150 151/* 152 * First index in the service_trees. 153 * IDLE is handled separately, so it has negative index 154 */ 155enum wl_prio_t { 156 BE_WORKLOAD = 0, 157 RT_WORKLOAD = 1, 158 IDLE_WORKLOAD = 2, 159 CFQ_PRIO_NR, 160}; 161 162/* 163 * Second index in the service_trees. 164 */ 165enum wl_type_t { 166 ASYNC_WORKLOAD = 0, 167 SYNC_NOIDLE_WORKLOAD = 1, 168 SYNC_WORKLOAD = 2 169}; 170 171/* This is per cgroup per device grouping structure */ 172struct cfq_group { 173 /* group service_tree member */ 174 struct rb_node rb_node; 175 176 /* group service_tree key */ 177 u64 vdisktime; 178 unsigned int weight; 179 unsigned int new_weight; 180 bool needs_update; 181 182 /* number of cfqq currently on this group */ 183 int nr_cfqq; 184 185 /* 186 * Per group busy queues average. Useful for workload slice calc. We 187 * create the array for each prio class but at run time it is used 188 * only for RT and BE class and slot for IDLE class remains unused. 189 * This is primarily done to avoid confusion and a gcc warning. 190 */ 191 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 192 /* 193 * rr lists of queues with requests. We maintain service trees for 194 * RT and BE classes. These trees are subdivided in subclasses 195 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 196 * class there is no subclassification and all the cfq queues go on 197 * a single tree service_tree_idle. 198 * Counts are embedded in the cfq_rb_root 199 */ 200 struct cfq_rb_root service_trees[2][3]; 201 struct cfq_rb_root service_tree_idle; 202 203 unsigned long saved_workload_slice; 204 enum wl_type_t saved_workload; 205 enum wl_prio_t saved_serving_prio; 206 struct blkio_group blkg; 207#ifdef CONFIG_CFQ_GROUP_IOSCHED 208 struct hlist_node cfqd_node; 209 int ref; 210#endif 211 /* number of requests that are on the dispatch list or inside driver */ 212 int dispatched; 213}; 214 215/* 216 * Per block device queue structure 217 */ 218struct cfq_data { 219 struct request_queue *queue; 220 /* Root service tree for cfq_groups */ 221 struct cfq_rb_root grp_service_tree; 222 struct cfq_group root_group; 223 224 /* 225 * The priority currently being served 226 */ 227 enum wl_prio_t serving_prio; 228 enum wl_type_t serving_type; 229 unsigned long workload_expires; 230 struct cfq_group *serving_group; 231 232 /* 233 * Each priority tree is sorted by next_request position. These 234 * trees are used when determining if two or more queues are 235 * interleaving requests (see cfq_close_cooperator). 236 */ 237 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 238 239 unsigned int busy_queues; 240 unsigned int busy_sync_queues; 241 242 int rq_in_driver; 243 int rq_in_flight[2]; 244 245 /* 246 * queue-depth detection 247 */ 248 int rq_queued; 249 int hw_tag; 250 /* 251 * hw_tag can be 252 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 253 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 254 * 0 => no NCQ 255 */ 256 int hw_tag_est_depth; 257 unsigned int hw_tag_samples; 258 259 /* 260 * idle window management 261 */ 262 struct timer_list idle_slice_timer; 263 struct work_struct unplug_work; 264 265 struct cfq_queue *active_queue; 266 struct cfq_io_context *active_cic; 267 268 /* 269 * async queue for each priority case 270 */ 271 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 272 struct cfq_queue *async_idle_cfqq; 273 274 sector_t last_position; 275 276 /* 277 * tunables, see top of file 278 */ 279 unsigned int cfq_quantum; 280 unsigned int cfq_fifo_expire[2]; 281 unsigned int cfq_back_penalty; 282 unsigned int cfq_back_max; 283 unsigned int cfq_slice[2]; 284 unsigned int cfq_slice_async_rq; 285 unsigned int cfq_slice_idle; 286 unsigned int cfq_group_idle; 287 unsigned int cfq_latency; 288 289 unsigned int cic_index; 290 struct list_head cic_list; 291 292 /* 293 * Fallback dummy cfqq for extreme OOM conditions 294 */ 295 struct cfq_queue oom_cfqq; 296 297 unsigned long last_delayed_sync; 298 299 /* List of cfq groups being managed on this device*/ 300 struct hlist_head cfqg_list; 301 302 /* Number of groups which are on blkcg->blkg_list */ 303 unsigned int nr_blkcg_linked_grps; 304}; 305 306static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 307 308static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 309 enum wl_prio_t prio, 310 enum wl_type_t type) 311{ 312 if (!cfqg) 313 return NULL; 314 315 if (prio == IDLE_WORKLOAD) 316 return &cfqg->service_tree_idle; 317 318 return &cfqg->service_trees[prio][type]; 319} 320 321enum cfqq_state_flags { 322 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 323 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 324 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 325 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 326 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 327 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 328 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 329 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 330 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 331 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 332 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 333 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 334 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 335}; 336 337#define CFQ_CFQQ_FNS(name) \ 338static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 339{ \ 340 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 341} \ 342static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 343{ \ 344 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 345} \ 346static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 347{ \ 348 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 349} 350 351CFQ_CFQQ_FNS(on_rr); 352CFQ_CFQQ_FNS(wait_request); 353CFQ_CFQQ_FNS(must_dispatch); 354CFQ_CFQQ_FNS(must_alloc_slice); 355CFQ_CFQQ_FNS(fifo_expire); 356CFQ_CFQQ_FNS(idle_window); 357CFQ_CFQQ_FNS(prio_changed); 358CFQ_CFQQ_FNS(slice_new); 359CFQ_CFQQ_FNS(sync); 360CFQ_CFQQ_FNS(coop); 361CFQ_CFQQ_FNS(split_coop); 362CFQ_CFQQ_FNS(deep); 363CFQ_CFQQ_FNS(wait_busy); 364#undef CFQ_CFQQ_FNS 365 366#ifdef CONFIG_CFQ_GROUP_IOSCHED 367#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 368 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 369 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 370 blkg_path(&(cfqq)->cfqg->blkg), ##args) 371 372#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 373 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 374 blkg_path(&(cfqg)->blkg), ##args) \ 375 376#else 377#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 378 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 379#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 380#endif 381#define cfq_log(cfqd, fmt, args...) \ 382 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 383 384/* Traverses through cfq group service trees */ 385#define for_each_cfqg_st(cfqg, i, j, st) \ 386 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 387 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 388 : &cfqg->service_tree_idle; \ 389 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 390 (i == IDLE_WORKLOAD && j == 0); \ 391 j++, st = i < IDLE_WORKLOAD ? \ 392 &cfqg->service_trees[i][j]: NULL) \ 393 394 395static inline bool iops_mode(struct cfq_data *cfqd) 396{ 397 /* 398 * If we are not idling on queues and it is a NCQ drive, parallel 399 * execution of requests is on and measuring time is not possible 400 * in most of the cases until and unless we drive shallower queue 401 * depths and that becomes a performance bottleneck. In such cases 402 * switch to start providing fairness in terms of number of IOs. 403 */ 404 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 405 return true; 406 else 407 return false; 408} 409 410static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 411{ 412 if (cfq_class_idle(cfqq)) 413 return IDLE_WORKLOAD; 414 if (cfq_class_rt(cfqq)) 415 return RT_WORKLOAD; 416 return BE_WORKLOAD; 417} 418 419 420static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 421{ 422 if (!cfq_cfqq_sync(cfqq)) 423 return ASYNC_WORKLOAD; 424 if (!cfq_cfqq_idle_window(cfqq)) 425 return SYNC_NOIDLE_WORKLOAD; 426 return SYNC_WORKLOAD; 427} 428 429static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 430 struct cfq_data *cfqd, 431 struct cfq_group *cfqg) 432{ 433 if (wl == IDLE_WORKLOAD) 434 return cfqg->service_tree_idle.count; 435 436 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 437 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 438 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 439} 440 441static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 442 struct cfq_group *cfqg) 443{ 444 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 445 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 446} 447 448static void cfq_dispatch_insert(struct request_queue *, struct request *); 449static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, 450 struct io_context *, gfp_t); 451static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, 452 struct io_context *); 453 454static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, 455 bool is_sync) 456{ 457 return cic->cfqq[is_sync]; 458} 459 460static inline void cic_set_cfqq(struct cfq_io_context *cic, 461 struct cfq_queue *cfqq, bool is_sync) 462{ 463 cic->cfqq[is_sync] = cfqq; 464} 465 466#define CIC_DEAD_KEY 1ul 467#define CIC_DEAD_INDEX_SHIFT 1 468 469static inline void *cfqd_dead_key(struct cfq_data *cfqd) 470{ 471 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); 472} 473 474static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) 475{ 476 struct cfq_data *cfqd = cic->key; 477 478 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY)) 479 return NULL; 480 481 return cfqd; 482} 483 484/* 485 * We regard a request as SYNC, if it's either a read or has the SYNC bit 486 * set (in which case it could also be direct WRITE). 487 */ 488static inline bool cfq_bio_sync(struct bio *bio) 489{ 490 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 491} 492 493/* 494 * scheduler run of queue, if there are requests pending and no one in the 495 * driver that will restart queueing 496 */ 497static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 498{ 499 if (cfqd->busy_queues) { 500 cfq_log(cfqd, "schedule dispatch"); 501 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 502 } 503} 504 505/* 506 * Scale schedule slice based on io priority. Use the sync time slice only 507 * if a queue is marked sync and has sync io queued. A sync queue with async 508 * io only, should not get full sync slice length. 509 */ 510static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 511 unsigned short prio) 512{ 513 const int base_slice = cfqd->cfq_slice[sync]; 514 515 WARN_ON(prio >= IOPRIO_BE_NR); 516 517 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 518} 519 520static inline int 521cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 522{ 523 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 524} 525 526static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 527{ 528 u64 d = delta << CFQ_SERVICE_SHIFT; 529 530 d = d * BLKIO_WEIGHT_DEFAULT; 531 do_div(d, cfqg->weight); 532 return d; 533} 534 535static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 536{ 537 s64 delta = (s64)(vdisktime - min_vdisktime); 538 if (delta > 0) 539 min_vdisktime = vdisktime; 540 541 return min_vdisktime; 542} 543 544static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 545{ 546 s64 delta = (s64)(vdisktime - min_vdisktime); 547 if (delta < 0) 548 min_vdisktime = vdisktime; 549 550 return min_vdisktime; 551} 552 553static void update_min_vdisktime(struct cfq_rb_root *st) 554{ 555 struct cfq_group *cfqg; 556 557 if (st->left) { 558 cfqg = rb_entry_cfqg(st->left); 559 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 560 cfqg->vdisktime); 561 } 562} 563 564/* 565 * get averaged number of queues of RT/BE priority. 566 * average is updated, with a formula that gives more weight to higher numbers, 567 * to quickly follows sudden increases and decrease slowly 568 */ 569 570static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 571 struct cfq_group *cfqg, bool rt) 572{ 573 unsigned min_q, max_q; 574 unsigned mult = cfq_hist_divisor - 1; 575 unsigned round = cfq_hist_divisor / 2; 576 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 577 578 min_q = min(cfqg->busy_queues_avg[rt], busy); 579 max_q = max(cfqg->busy_queues_avg[rt], busy); 580 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 581 cfq_hist_divisor; 582 return cfqg->busy_queues_avg[rt]; 583} 584 585static inline unsigned 586cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 587{ 588 struct cfq_rb_root *st = &cfqd->grp_service_tree; 589 590 return cfq_target_latency * cfqg->weight / st->total_weight; 591} 592 593static inline unsigned 594cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 595{ 596 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 597 if (cfqd->cfq_latency) { 598 /* 599 * interested queues (we consider only the ones with the same 600 * priority class in the cfq group) 601 */ 602 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 603 cfq_class_rt(cfqq)); 604 unsigned sync_slice = cfqd->cfq_slice[1]; 605 unsigned expect_latency = sync_slice * iq; 606 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 607 608 if (expect_latency > group_slice) { 609 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 610 /* scale low_slice according to IO priority 611 * and sync vs async */ 612 unsigned low_slice = 613 min(slice, base_low_slice * slice / sync_slice); 614 /* the adapted slice value is scaled to fit all iqs 615 * into the target latency */ 616 slice = max(slice * group_slice / expect_latency, 617 low_slice); 618 } 619 } 620 return slice; 621} 622 623static inline void 624cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 625{ 626 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 627 628 cfqq->slice_start = jiffies; 629 cfqq->slice_end = jiffies + slice; 630 cfqq->allocated_slice = slice; 631 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 632} 633 634/* 635 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 636 * isn't valid until the first request from the dispatch is activated 637 * and the slice time set. 638 */ 639static inline bool cfq_slice_used(struct cfq_queue *cfqq) 640{ 641 if (cfq_cfqq_slice_new(cfqq)) 642 return false; 643 if (time_before(jiffies, cfqq->slice_end)) 644 return false; 645 646 return true; 647} 648 649/* 650 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 651 * We choose the request that is closest to the head right now. Distance 652 * behind the head is penalized and only allowed to a certain extent. 653 */ 654static struct request * 655cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 656{ 657 sector_t s1, s2, d1 = 0, d2 = 0; 658 unsigned long back_max; 659#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 660#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 661 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 662 663 if (rq1 == NULL || rq1 == rq2) 664 return rq2; 665 if (rq2 == NULL) 666 return rq1; 667 668 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 669 return rq_is_sync(rq1) ? rq1 : rq2; 670 671 s1 = blk_rq_pos(rq1); 672 s2 = blk_rq_pos(rq2); 673 674 /* 675 * by definition, 1KiB is 2 sectors 676 */ 677 back_max = cfqd->cfq_back_max * 2; 678 679 /* 680 * Strict one way elevator _except_ in the case where we allow 681 * short backward seeks which are biased as twice the cost of a 682 * similar forward seek. 683 */ 684 if (s1 >= last) 685 d1 = s1 - last; 686 else if (s1 + back_max >= last) 687 d1 = (last - s1) * cfqd->cfq_back_penalty; 688 else 689 wrap |= CFQ_RQ1_WRAP; 690 691 if (s2 >= last) 692 d2 = s2 - last; 693 else if (s2 + back_max >= last) 694 d2 = (last - s2) * cfqd->cfq_back_penalty; 695 else 696 wrap |= CFQ_RQ2_WRAP; 697 698 /* Found required data */ 699 700 /* 701 * By doing switch() on the bit mask "wrap" we avoid having to 702 * check two variables for all permutations: --> faster! 703 */ 704 switch (wrap) { 705 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 706 if (d1 < d2) 707 return rq1; 708 else if (d2 < d1) 709 return rq2; 710 else { 711 if (s1 >= s2) 712 return rq1; 713 else 714 return rq2; 715 } 716 717 case CFQ_RQ2_WRAP: 718 return rq1; 719 case CFQ_RQ1_WRAP: 720 return rq2; 721 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 722 default: 723 /* 724 * Since both rqs are wrapped, 725 * start with the one that's further behind head 726 * (--> only *one* back seek required), 727 * since back seek takes more time than forward. 728 */ 729 if (s1 <= s2) 730 return rq1; 731 else 732 return rq2; 733 } 734} 735 736/* 737 * The below is leftmost cache rbtree addon 738 */ 739static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 740{ 741 /* Service tree is empty */ 742 if (!root->count) 743 return NULL; 744 745 if (!root->left) 746 root->left = rb_first(&root->rb); 747 748 if (root->left) 749 return rb_entry(root->left, struct cfq_queue, rb_node); 750 751 return NULL; 752} 753 754static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 755{ 756 if (!root->left) 757 root->left = rb_first(&root->rb); 758 759 if (root->left) 760 return rb_entry_cfqg(root->left); 761 762 return NULL; 763} 764 765static void rb_erase_init(struct rb_node *n, struct rb_root *root) 766{ 767 rb_erase(n, root); 768 RB_CLEAR_NODE(n); 769} 770 771static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 772{ 773 if (root->left == n) 774 root->left = NULL; 775 rb_erase_init(n, &root->rb); 776 --root->count; 777} 778 779/* 780 * would be nice to take fifo expire time into account as well 781 */ 782static struct request * 783cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 784 struct request *last) 785{ 786 struct rb_node *rbnext = rb_next(&last->rb_node); 787 struct rb_node *rbprev = rb_prev(&last->rb_node); 788 struct request *next = NULL, *prev = NULL; 789 790 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 791 792 if (rbprev) 793 prev = rb_entry_rq(rbprev); 794 795 if (rbnext) 796 next = rb_entry_rq(rbnext); 797 else { 798 rbnext = rb_first(&cfqq->sort_list); 799 if (rbnext && rbnext != &last->rb_node) 800 next = rb_entry_rq(rbnext); 801 } 802 803 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 804} 805 806static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 807 struct cfq_queue *cfqq) 808{ 809 /* 810 * just an approximation, should be ok. 811 */ 812 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 813 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 814} 815 816static inline s64 817cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 818{ 819 return cfqg->vdisktime - st->min_vdisktime; 820} 821 822static void 823__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 824{ 825 struct rb_node **node = &st->rb.rb_node; 826 struct rb_node *parent = NULL; 827 struct cfq_group *__cfqg; 828 s64 key = cfqg_key(st, cfqg); 829 int left = 1; 830 831 while (*node != NULL) { 832 parent = *node; 833 __cfqg = rb_entry_cfqg(parent); 834 835 if (key < cfqg_key(st, __cfqg)) 836 node = &parent->rb_left; 837 else { 838 node = &parent->rb_right; 839 left = 0; 840 } 841 } 842 843 if (left) 844 st->left = &cfqg->rb_node; 845 846 rb_link_node(&cfqg->rb_node, parent, node); 847 rb_insert_color(&cfqg->rb_node, &st->rb); 848} 849 850static void 851cfq_update_group_weight(struct cfq_group *cfqg) 852{ 853 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 854 if (cfqg->needs_update) { 855 cfqg->weight = cfqg->new_weight; 856 cfqg->needs_update = false; 857 } 858} 859 860static void 861cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 862{ 863 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 864 865 cfq_update_group_weight(cfqg); 866 __cfq_group_service_tree_add(st, cfqg); 867 st->total_weight += cfqg->weight; 868} 869 870static void 871cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 872{ 873 struct cfq_rb_root *st = &cfqd->grp_service_tree; 874 struct cfq_group *__cfqg; 875 struct rb_node *n; 876 877 cfqg->nr_cfqq++; 878 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 879 return; 880 881 /* 882 * Currently put the group at the end. Later implement something 883 * so that groups get lesser vtime based on their weights, so that 884 * if group does not loose all if it was not continuously backlogged. 885 */ 886 n = rb_last(&st->rb); 887 if (n) { 888 __cfqg = rb_entry_cfqg(n); 889 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 890 } else 891 cfqg->vdisktime = st->min_vdisktime; 892 cfq_group_service_tree_add(st, cfqg); 893} 894 895static void 896cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 897{ 898 st->total_weight -= cfqg->weight; 899 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 900 cfq_rb_erase(&cfqg->rb_node, st); 901} 902 903static void 904cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 905{ 906 struct cfq_rb_root *st = &cfqd->grp_service_tree; 907 908 BUG_ON(cfqg->nr_cfqq < 1); 909 cfqg->nr_cfqq--; 910 911 /* If there are other cfq queues under this group, don't delete it */ 912 if (cfqg->nr_cfqq) 913 return; 914 915 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 916 cfq_group_service_tree_del(st, cfqg); 917 cfqg->saved_workload_slice = 0; 918 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); 919} 920 921static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 922 unsigned int *unaccounted_time) 923{ 924 unsigned int slice_used; 925 926 /* 927 * Queue got expired before even a single request completed or 928 * got expired immediately after first request completion. 929 */ 930 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 931 /* 932 * Also charge the seek time incurred to the group, otherwise 933 * if there are mutiple queues in the group, each can dispatch 934 * a single request on seeky media and cause lots of seek time 935 * and group will never know it. 936 */ 937 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 938 1); 939 } else { 940 slice_used = jiffies - cfqq->slice_start; 941 if (slice_used > cfqq->allocated_slice) { 942 *unaccounted_time = slice_used - cfqq->allocated_slice; 943 slice_used = cfqq->allocated_slice; 944 } 945 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 946 *unaccounted_time += cfqq->slice_start - 947 cfqq->dispatch_start; 948 } 949 950 return slice_used; 951} 952 953static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 954 struct cfq_queue *cfqq) 955{ 956 struct cfq_rb_root *st = &cfqd->grp_service_tree; 957 unsigned int used_sl, charge, unaccounted_sl = 0; 958 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 959 - cfqg->service_tree_idle.count; 960 961 BUG_ON(nr_sync < 0); 962 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 963 964 if (iops_mode(cfqd)) 965 charge = cfqq->slice_dispatch; 966 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 967 charge = cfqq->allocated_slice; 968 969 /* Can't update vdisktime while group is on service tree */ 970 cfq_group_service_tree_del(st, cfqg); 971 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 972 /* If a new weight was requested, update now, off tree */ 973 cfq_group_service_tree_add(st, cfqg); 974 975 /* This group is being expired. Save the context */ 976 if (time_after(cfqd->workload_expires, jiffies)) { 977 cfqg->saved_workload_slice = cfqd->workload_expires 978 - jiffies; 979 cfqg->saved_workload = cfqd->serving_type; 980 cfqg->saved_serving_prio = cfqd->serving_prio; 981 } else 982 cfqg->saved_workload_slice = 0; 983 984 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 985 st->min_vdisktime); 986 cfq_log_cfqq(cfqq->cfqd, cfqq, 987 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 988 used_sl, cfqq->slice_dispatch, charge, 989 iops_mode(cfqd), cfqq->nr_sectors); 990 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, 991 unaccounted_sl); 992 cfq_blkiocg_set_start_empty_time(&cfqg->blkg); 993} 994 995#ifdef CONFIG_CFQ_GROUP_IOSCHED 996static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 997{ 998 if (blkg) 999 return container_of(blkg, struct cfq_group, blkg); 1000 return NULL; 1001} 1002 1003static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, 1004 unsigned int weight) 1005{ 1006 struct cfq_group *cfqg = cfqg_of_blkg(blkg); 1007 cfqg->new_weight = weight; 1008 cfqg->needs_update = true; 1009} 1010 1011static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, 1012 struct cfq_group *cfqg, struct blkio_cgroup *blkcg) 1013{ 1014 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1015 unsigned int major, minor; 1016 1017 /* 1018 * Add group onto cgroup list. It might happen that bdi->dev is 1019 * not initialized yet. Initialize this new group without major 1020 * and minor info and this info will be filled in once a new thread 1021 * comes for IO. 1022 */ 1023 if (bdi->dev) { 1024 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1025 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1026 (void *)cfqd, MKDEV(major, minor)); 1027 } else 1028 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1029 (void *)cfqd, 0); 1030 1031 cfqd->nr_blkcg_linked_grps++; 1032 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); 1033 1034 /* Add group on cfqd list */ 1035 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 1036} 1037 1038/* 1039 * Should be called from sleepable context. No request queue lock as per 1040 * cpu stats are allocated dynamically and alloc_percpu needs to be called 1041 * from sleepable context. 1042 */ 1043static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) 1044{ 1045 struct cfq_group *cfqg = NULL; 1046 int i, j, ret; 1047 struct cfq_rb_root *st; 1048 1049 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 1050 if (!cfqg) 1051 return NULL; 1052 1053 for_each_cfqg_st(cfqg, i, j, st) 1054 *st = CFQ_RB_ROOT; 1055 RB_CLEAR_NODE(&cfqg->rb_node); 1056 1057 /* 1058 * Take the initial reference that will be released on destroy 1059 * This can be thought of a joint reference by cgroup and 1060 * elevator which will be dropped by either elevator exit 1061 * or cgroup deletion path depending on who is exiting first. 1062 */ 1063 cfqg->ref = 1; 1064 1065 ret = blkio_alloc_blkg_stats(&cfqg->blkg); 1066 if (ret) { 1067 kfree(cfqg); 1068 return NULL; 1069 } 1070 1071 return cfqg; 1072} 1073 1074static struct cfq_group * 1075cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) 1076{ 1077 struct cfq_group *cfqg = NULL; 1078 void *key = cfqd; 1079 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1080 unsigned int major, minor; 1081 1082 /* 1083 * This is the common case when there are no blkio cgroups. 1084 * Avoid lookup in this case 1085 */ 1086 if (blkcg == &blkio_root_cgroup) 1087 cfqg = &cfqd->root_group; 1088 else 1089 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); 1090 1091 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { 1092 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1093 cfqg->blkg.dev = MKDEV(major, minor); 1094 } 1095 1096 return cfqg; 1097} 1098 1099/* 1100 * Search for the cfq group current task belongs to. request_queue lock must 1101 * be held. 1102 */ 1103static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1104{ 1105 struct blkio_cgroup *blkcg; 1106 struct cfq_group *cfqg = NULL, *__cfqg = NULL; 1107 struct request_queue *q = cfqd->queue; 1108 1109 rcu_read_lock(); 1110 blkcg = task_blkio_cgroup(current); 1111 cfqg = cfq_find_cfqg(cfqd, blkcg); 1112 if (cfqg) { 1113 rcu_read_unlock(); 1114 return cfqg; 1115 } 1116 1117 /* 1118 * Need to allocate a group. Allocation of group also needs allocation 1119 * of per cpu stats which in-turn takes a mutex() and can block. Hence 1120 * we need to drop rcu lock and queue_lock before we call alloc. 1121 * 1122 * Not taking any queue reference here and assuming that queue is 1123 * around by the time we return. CFQ queue allocation code does 1124 * the same. It might be racy though. 1125 */ 1126 1127 rcu_read_unlock(); 1128 spin_unlock_irq(q->queue_lock); 1129 1130 cfqg = cfq_alloc_cfqg(cfqd); 1131 1132 spin_lock_irq(q->queue_lock); 1133 1134 rcu_read_lock(); 1135 blkcg = task_blkio_cgroup(current); 1136 1137 /* 1138 * If some other thread already allocated the group while we were 1139 * not holding queue lock, free up the group 1140 */ 1141 __cfqg = cfq_find_cfqg(cfqd, blkcg); 1142 1143 if (__cfqg) { 1144 kfree(cfqg); 1145 rcu_read_unlock(); 1146 return __cfqg; 1147 } 1148 1149 if (!cfqg) 1150 cfqg = &cfqd->root_group; 1151 1152 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); 1153 rcu_read_unlock(); 1154 return cfqg; 1155} 1156 1157static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1158{ 1159 cfqg->ref++; 1160 return cfqg; 1161} 1162 1163static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1164{ 1165 /* Currently, all async queues are mapped to root group */ 1166 if (!cfq_cfqq_sync(cfqq)) 1167 cfqg = &cfqq->cfqd->root_group; 1168 1169 cfqq->cfqg = cfqg; 1170 /* cfqq reference on cfqg */ 1171 cfqq->cfqg->ref++; 1172} 1173 1174static void cfq_put_cfqg(struct cfq_group *cfqg) 1175{ 1176 struct cfq_rb_root *st; 1177 int i, j; 1178 1179 BUG_ON(cfqg->ref <= 0); 1180 cfqg->ref--; 1181 if (cfqg->ref) 1182 return; 1183 for_each_cfqg_st(cfqg, i, j, st) 1184 BUG_ON(!RB_EMPTY_ROOT(&st->rb)); 1185 free_percpu(cfqg->blkg.stats_cpu); 1186 kfree(cfqg); 1187} 1188 1189static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1190{ 1191 /* Something wrong if we are trying to remove same group twice */ 1192 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1193 1194 hlist_del_init(&cfqg->cfqd_node); 1195 1196 /* 1197 * Put the reference taken at the time of creation so that when all 1198 * queues are gone, group can be destroyed. 1199 */ 1200 cfq_put_cfqg(cfqg); 1201} 1202 1203static void cfq_release_cfq_groups(struct cfq_data *cfqd) 1204{ 1205 struct hlist_node *pos, *n; 1206 struct cfq_group *cfqg; 1207 1208 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1209 /* 1210 * If cgroup removal path got to blk_group first and removed 1211 * it from cgroup list, then it will take care of destroying 1212 * cfqg also. 1213 */ 1214 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) 1215 cfq_destroy_cfqg(cfqd, cfqg); 1216 } 1217} 1218 1219/* 1220 * Blk cgroup controller notification saying that blkio_group object is being 1221 * delinked as associated cgroup object is going away. That also means that 1222 * no new IO will come in this group. So get rid of this group as soon as 1223 * any pending IO in the group is finished. 1224 * 1225 * This function is called under rcu_read_lock(). key is the rcu protected 1226 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu 1227 * read lock. 1228 * 1229 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means 1230 * it should not be NULL as even if elevator was exiting, cgroup deltion 1231 * path got to it first. 1232 */ 1233static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) 1234{ 1235 unsigned long flags; 1236 struct cfq_data *cfqd = key; 1237 1238 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 1239 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1240 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 1241} 1242 1243#else /* GROUP_IOSCHED */ 1244static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1245{ 1246 return &cfqd->root_group; 1247} 1248 1249static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1250{ 1251 return cfqg; 1252} 1253 1254static inline void 1255cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1256 cfqq->cfqg = cfqg; 1257} 1258 1259static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1260static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1261 1262#endif /* GROUP_IOSCHED */ 1263 1264/* 1265 * The cfqd->service_trees holds all pending cfq_queue's that have 1266 * requests waiting to be processed. It is sorted in the order that 1267 * we will service the queues. 1268 */ 1269static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1270 bool add_front) 1271{ 1272 struct rb_node **p, *parent; 1273 struct cfq_queue *__cfqq; 1274 unsigned long rb_key; 1275 struct cfq_rb_root *service_tree; 1276 int left; 1277 int new_cfqq = 1; 1278 1279 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1280 cfqq_type(cfqq)); 1281 if (cfq_class_idle(cfqq)) { 1282 rb_key = CFQ_IDLE_DELAY; 1283 parent = rb_last(&service_tree->rb); 1284 if (parent && parent != &cfqq->rb_node) { 1285 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1286 rb_key += __cfqq->rb_key; 1287 } else 1288 rb_key += jiffies; 1289 } else if (!add_front) { 1290 /* 1291 * Get our rb key offset. Subtract any residual slice 1292 * value carried from last service. A negative resid 1293 * count indicates slice overrun, and this should position 1294 * the next service time further away in the tree. 1295 */ 1296 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1297 rb_key -= cfqq->slice_resid; 1298 cfqq->slice_resid = 0; 1299 } else { 1300 rb_key = -HZ; 1301 __cfqq = cfq_rb_first(service_tree); 1302 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1303 } 1304 1305 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1306 new_cfqq = 0; 1307 /* 1308 * same position, nothing more to do 1309 */ 1310 if (rb_key == cfqq->rb_key && 1311 cfqq->service_tree == service_tree) 1312 return; 1313 1314 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1315 cfqq->service_tree = NULL; 1316 } 1317 1318 left = 1; 1319 parent = NULL; 1320 cfqq->service_tree = service_tree; 1321 p = &service_tree->rb.rb_node; 1322 while (*p) { 1323 struct rb_node **n; 1324 1325 parent = *p; 1326 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1327 1328 /* 1329 * sort by key, that represents service time. 1330 */ 1331 if (time_before(rb_key, __cfqq->rb_key)) 1332 n = &(*p)->rb_left; 1333 else { 1334 n = &(*p)->rb_right; 1335 left = 0; 1336 } 1337 1338 p = n; 1339 } 1340 1341 if (left) 1342 service_tree->left = &cfqq->rb_node; 1343 1344 cfqq->rb_key = rb_key; 1345 rb_link_node(&cfqq->rb_node, parent, p); 1346 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1347 service_tree->count++; 1348 if (add_front || !new_cfqq) 1349 return; 1350 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1351} 1352 1353static struct cfq_queue * 1354cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1355 sector_t sector, struct rb_node **ret_parent, 1356 struct rb_node ***rb_link) 1357{ 1358 struct rb_node **p, *parent; 1359 struct cfq_queue *cfqq = NULL; 1360 1361 parent = NULL; 1362 p = &root->rb_node; 1363 while (*p) { 1364 struct rb_node **n; 1365 1366 parent = *p; 1367 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1368 1369 /* 1370 * Sort strictly based on sector. Smallest to the left, 1371 * largest to the right. 1372 */ 1373 if (sector > blk_rq_pos(cfqq->next_rq)) 1374 n = &(*p)->rb_right; 1375 else if (sector < blk_rq_pos(cfqq->next_rq)) 1376 n = &(*p)->rb_left; 1377 else 1378 break; 1379 p = n; 1380 cfqq = NULL; 1381 } 1382 1383 *ret_parent = parent; 1384 if (rb_link) 1385 *rb_link = p; 1386 return cfqq; 1387} 1388 1389static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1390{ 1391 struct rb_node **p, *parent; 1392 struct cfq_queue *__cfqq; 1393 1394 if (cfqq->p_root) { 1395 rb_erase(&cfqq->p_node, cfqq->p_root); 1396 cfqq->p_root = NULL; 1397 } 1398 1399 if (cfq_class_idle(cfqq)) 1400 return; 1401 if (!cfqq->next_rq) 1402 return; 1403 1404 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1405 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1406 blk_rq_pos(cfqq->next_rq), &parent, &p); 1407 if (!__cfqq) { 1408 rb_link_node(&cfqq->p_node, parent, p); 1409 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1410 } else 1411 cfqq->p_root = NULL; 1412} 1413 1414/* 1415 * Update cfqq's position in the service tree. 1416 */ 1417static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1418{ 1419 /* 1420 * Resorting requires the cfqq to be on the RR list already. 1421 */ 1422 if (cfq_cfqq_on_rr(cfqq)) { 1423 cfq_service_tree_add(cfqd, cfqq, 0); 1424 cfq_prio_tree_add(cfqd, cfqq); 1425 } 1426} 1427 1428/* 1429 * add to busy list of queues for service, trying to be fair in ordering 1430 * the pending list according to last request service 1431 */ 1432static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1433{ 1434 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1435 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1436 cfq_mark_cfqq_on_rr(cfqq); 1437 cfqd->busy_queues++; 1438 if (cfq_cfqq_sync(cfqq)) 1439 cfqd->busy_sync_queues++; 1440 1441 cfq_resort_rr_list(cfqd, cfqq); 1442} 1443 1444/* 1445 * Called when the cfqq no longer has requests pending, remove it from 1446 * the service tree. 1447 */ 1448static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1449{ 1450 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1451 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1452 cfq_clear_cfqq_on_rr(cfqq); 1453 1454 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1455 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1456 cfqq->service_tree = NULL; 1457 } 1458 if (cfqq->p_root) { 1459 rb_erase(&cfqq->p_node, cfqq->p_root); 1460 cfqq->p_root = NULL; 1461 } 1462 1463 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1464 BUG_ON(!cfqd->busy_queues); 1465 cfqd->busy_queues--; 1466 if (cfq_cfqq_sync(cfqq)) 1467 cfqd->busy_sync_queues--; 1468} 1469 1470/* 1471 * rb tree support functions 1472 */ 1473static void cfq_del_rq_rb(struct request *rq) 1474{ 1475 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1476 const int sync = rq_is_sync(rq); 1477 1478 BUG_ON(!cfqq->queued[sync]); 1479 cfqq->queued[sync]--; 1480 1481 elv_rb_del(&cfqq->sort_list, rq); 1482 1483 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1484 /* 1485 * Queue will be deleted from service tree when we actually 1486 * expire it later. Right now just remove it from prio tree 1487 * as it is empty. 1488 */ 1489 if (cfqq->p_root) { 1490 rb_erase(&cfqq->p_node, cfqq->p_root); 1491 cfqq->p_root = NULL; 1492 } 1493 } 1494} 1495 1496static void cfq_add_rq_rb(struct request *rq) 1497{ 1498 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1499 struct cfq_data *cfqd = cfqq->cfqd; 1500 struct request *prev; 1501 1502 cfqq->queued[rq_is_sync(rq)]++; 1503 1504 elv_rb_add(&cfqq->sort_list, rq); 1505 1506 if (!cfq_cfqq_on_rr(cfqq)) 1507 cfq_add_cfqq_rr(cfqd, cfqq); 1508 1509 /* 1510 * check if this request is a better next-serve candidate 1511 */ 1512 prev = cfqq->next_rq; 1513 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1514 1515 /* 1516 * adjust priority tree position, if ->next_rq changes 1517 */ 1518 if (prev != cfqq->next_rq) 1519 cfq_prio_tree_add(cfqd, cfqq); 1520 1521 BUG_ON(!cfqq->next_rq); 1522} 1523 1524static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1525{ 1526 elv_rb_del(&cfqq->sort_list, rq); 1527 cfqq->queued[rq_is_sync(rq)]--; 1528 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1529 rq_data_dir(rq), rq_is_sync(rq)); 1530 cfq_add_rq_rb(rq); 1531 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 1532 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), 1533 rq_is_sync(rq)); 1534} 1535 1536static struct request * 1537cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1538{ 1539 struct task_struct *tsk = current; 1540 struct cfq_io_context *cic; 1541 struct cfq_queue *cfqq; 1542 1543 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1544 if (!cic) 1545 return NULL; 1546 1547 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1548 if (cfqq) { 1549 sector_t sector = bio->bi_sector + bio_sectors(bio); 1550 1551 return elv_rb_find(&cfqq->sort_list, sector); 1552 } 1553 1554 return NULL; 1555} 1556 1557static void cfq_activate_request(struct request_queue *q, struct request *rq) 1558{ 1559 struct cfq_data *cfqd = q->elevator->elevator_data; 1560 1561 cfqd->rq_in_driver++; 1562 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1563 cfqd->rq_in_driver); 1564 1565 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1566} 1567 1568static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1569{ 1570 struct cfq_data *cfqd = q->elevator->elevator_data; 1571 1572 WARN_ON(!cfqd->rq_in_driver); 1573 cfqd->rq_in_driver--; 1574 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1575 cfqd->rq_in_driver); 1576} 1577 1578static void cfq_remove_request(struct request *rq) 1579{ 1580 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1581 1582 if (cfqq->next_rq == rq) 1583 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1584 1585 list_del_init(&rq->queuelist); 1586 cfq_del_rq_rb(rq); 1587 1588 cfqq->cfqd->rq_queued--; 1589 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1590 rq_data_dir(rq), rq_is_sync(rq)); 1591} 1592 1593static int cfq_merge(struct request_queue *q, struct request **req, 1594 struct bio *bio) 1595{ 1596 struct cfq_data *cfqd = q->elevator->elevator_data; 1597 struct request *__rq; 1598 1599 __rq = cfq_find_rq_fmerge(cfqd, bio); 1600 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1601 *req = __rq; 1602 return ELEVATOR_FRONT_MERGE; 1603 } 1604 1605 return ELEVATOR_NO_MERGE; 1606} 1607 1608static void cfq_merged_request(struct request_queue *q, struct request *req, 1609 int type) 1610{ 1611 if (type == ELEVATOR_FRONT_MERGE) { 1612 struct cfq_queue *cfqq = RQ_CFQQ(req); 1613 1614 cfq_reposition_rq_rb(cfqq, req); 1615 } 1616} 1617 1618static void cfq_bio_merged(struct request_queue *q, struct request *req, 1619 struct bio *bio) 1620{ 1621 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, 1622 bio_data_dir(bio), cfq_bio_sync(bio)); 1623} 1624 1625static void 1626cfq_merged_requests(struct request_queue *q, struct request *rq, 1627 struct request *next) 1628{ 1629 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1630 /* 1631 * reposition in fifo if next is older than rq 1632 */ 1633 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1634 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1635 list_move(&rq->queuelist, &next->queuelist); 1636 rq_set_fifo_time(rq, rq_fifo_time(next)); 1637 } 1638 1639 if (cfqq->next_rq == next) 1640 cfqq->next_rq = rq; 1641 cfq_remove_request(next); 1642 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, 1643 rq_data_dir(next), rq_is_sync(next)); 1644} 1645 1646static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1647 struct bio *bio) 1648{ 1649 struct cfq_data *cfqd = q->elevator->elevator_data; 1650 struct cfq_io_context *cic; 1651 struct cfq_queue *cfqq; 1652 1653 /* 1654 * Disallow merge of a sync bio into an async request. 1655 */ 1656 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1657 return false; 1658 1659 /* 1660 * Lookup the cfqq that this bio will be queued with. Allow 1661 * merge only if rq is queued there. 1662 */ 1663 cic = cfq_cic_lookup(cfqd, current->io_context); 1664 if (!cic) 1665 return false; 1666 1667 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1668 return cfqq == RQ_CFQQ(rq); 1669} 1670 1671static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1672{ 1673 del_timer(&cfqd->idle_slice_timer); 1674 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); 1675} 1676 1677static void __cfq_set_active_queue(struct cfq_data *cfqd, 1678 struct cfq_queue *cfqq) 1679{ 1680 if (cfqq) { 1681 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1682 cfqd->serving_prio, cfqd->serving_type); 1683 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); 1684 cfqq->slice_start = 0; 1685 cfqq->dispatch_start = jiffies; 1686 cfqq->allocated_slice = 0; 1687 cfqq->slice_end = 0; 1688 cfqq->slice_dispatch = 0; 1689 cfqq->nr_sectors = 0; 1690 1691 cfq_clear_cfqq_wait_request(cfqq); 1692 cfq_clear_cfqq_must_dispatch(cfqq); 1693 cfq_clear_cfqq_must_alloc_slice(cfqq); 1694 cfq_clear_cfqq_fifo_expire(cfqq); 1695 cfq_mark_cfqq_slice_new(cfqq); 1696 1697 cfq_del_timer(cfqd, cfqq); 1698 } 1699 1700 cfqd->active_queue = cfqq; 1701} 1702 1703/* 1704 * current cfqq expired its slice (or was too idle), select new one 1705 */ 1706static void 1707__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1708 bool timed_out) 1709{ 1710 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1711 1712 if (cfq_cfqq_wait_request(cfqq)) 1713 cfq_del_timer(cfqd, cfqq); 1714 1715 cfq_clear_cfqq_wait_request(cfqq); 1716 cfq_clear_cfqq_wait_busy(cfqq); 1717 1718 /* 1719 * If this cfqq is shared between multiple processes, check to 1720 * make sure that those processes are still issuing I/Os within 1721 * the mean seek distance. If not, it may be time to break the 1722 * queues apart again. 1723 */ 1724 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1725 cfq_mark_cfqq_split_coop(cfqq); 1726 1727 /* 1728 * store what was left of this slice, if the queue idled/timed out 1729 */ 1730 if (timed_out) { 1731 if (cfq_cfqq_slice_new(cfqq)) 1732 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 1733 else 1734 cfqq->slice_resid = cfqq->slice_end - jiffies; 1735 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1736 } 1737 1738 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1739 1740 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1741 cfq_del_cfqq_rr(cfqd, cfqq); 1742 1743 cfq_resort_rr_list(cfqd, cfqq); 1744 1745 if (cfqq == cfqd->active_queue) 1746 cfqd->active_queue = NULL; 1747 1748 if (cfqd->active_cic) { 1749 put_io_context(cfqd->active_cic->ioc); 1750 cfqd->active_cic = NULL; 1751 } 1752} 1753 1754static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1755{ 1756 struct cfq_queue *cfqq = cfqd->active_queue; 1757 1758 if (cfqq) 1759 __cfq_slice_expired(cfqd, cfqq, timed_out); 1760} 1761 1762/* 1763 * Get next queue for service. Unless we have a queue preemption, 1764 * we'll simply select the first cfqq in the service tree. 1765 */ 1766static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1767{ 1768 struct cfq_rb_root *service_tree = 1769 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1770 cfqd->serving_type); 1771 1772 if (!cfqd->rq_queued) 1773 return NULL; 1774 1775 /* There is nothing to dispatch */ 1776 if (!service_tree) 1777 return NULL; 1778 if (RB_EMPTY_ROOT(&service_tree->rb)) 1779 return NULL; 1780 return cfq_rb_first(service_tree); 1781} 1782 1783static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1784{ 1785 struct cfq_group *cfqg; 1786 struct cfq_queue *cfqq; 1787 int i, j; 1788 struct cfq_rb_root *st; 1789 1790 if (!cfqd->rq_queued) 1791 return NULL; 1792 1793 cfqg = cfq_get_next_cfqg(cfqd); 1794 if (!cfqg) 1795 return NULL; 1796 1797 for_each_cfqg_st(cfqg, i, j, st) 1798 if ((cfqq = cfq_rb_first(st)) != NULL) 1799 return cfqq; 1800 return NULL; 1801} 1802 1803/* 1804 * Get and set a new active queue for service. 1805 */ 1806static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1807 struct cfq_queue *cfqq) 1808{ 1809 if (!cfqq) 1810 cfqq = cfq_get_next_queue(cfqd); 1811 1812 __cfq_set_active_queue(cfqd, cfqq); 1813 return cfqq; 1814} 1815 1816static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1817 struct request *rq) 1818{ 1819 if (blk_rq_pos(rq) >= cfqd->last_position) 1820 return blk_rq_pos(rq) - cfqd->last_position; 1821 else 1822 return cfqd->last_position - blk_rq_pos(rq); 1823} 1824 1825static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1826 struct request *rq) 1827{ 1828 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1829} 1830 1831static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1832 struct cfq_queue *cur_cfqq) 1833{ 1834 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1835 struct rb_node *parent, *node; 1836 struct cfq_queue *__cfqq; 1837 sector_t sector = cfqd->last_position; 1838 1839 if (RB_EMPTY_ROOT(root)) 1840 return NULL; 1841 1842 /* 1843 * First, if we find a request starting at the end of the last 1844 * request, choose it. 1845 */ 1846 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1847 if (__cfqq) 1848 return __cfqq; 1849 1850 /* 1851 * If the exact sector wasn't found, the parent of the NULL leaf 1852 * will contain the closest sector. 1853 */ 1854 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1855 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1856 return __cfqq; 1857 1858 if (blk_rq_pos(__cfqq->next_rq) < sector) 1859 node = rb_next(&__cfqq->p_node); 1860 else 1861 node = rb_prev(&__cfqq->p_node); 1862 if (!node) 1863 return NULL; 1864 1865 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1866 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1867 return __cfqq; 1868 1869 return NULL; 1870} 1871 1872/* 1873 * cfqd - obvious 1874 * cur_cfqq - passed in so that we don't decide that the current queue is 1875 * closely cooperating with itself. 1876 * 1877 * So, basically we're assuming that that cur_cfqq has dispatched at least 1878 * one request, and that cfqd->last_position reflects a position on the disk 1879 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1880 * assumption. 1881 */ 1882static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1883 struct cfq_queue *cur_cfqq) 1884{ 1885 struct cfq_queue *cfqq; 1886 1887 if (cfq_class_idle(cur_cfqq)) 1888 return NULL; 1889 if (!cfq_cfqq_sync(cur_cfqq)) 1890 return NULL; 1891 if (CFQQ_SEEKY(cur_cfqq)) 1892 return NULL; 1893 1894 /* 1895 * Don't search priority tree if it's the only queue in the group. 1896 */ 1897 if (cur_cfqq->cfqg->nr_cfqq == 1) 1898 return NULL; 1899 1900 /* 1901 * We should notice if some of the queues are cooperating, eg 1902 * working closely on the same area of the disk. In that case, 1903 * we can group them together and don't waste time idling. 1904 */ 1905 cfqq = cfqq_close(cfqd, cur_cfqq); 1906 if (!cfqq) 1907 return NULL; 1908 1909 /* If new queue belongs to different cfq_group, don't choose it */ 1910 if (cur_cfqq->cfqg != cfqq->cfqg) 1911 return NULL; 1912 1913 /* 1914 * It only makes sense to merge sync queues. 1915 */ 1916 if (!cfq_cfqq_sync(cfqq)) 1917 return NULL; 1918 if (CFQQ_SEEKY(cfqq)) 1919 return NULL; 1920 1921 /* 1922 * Do not merge queues of different priority classes 1923 */ 1924 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1925 return NULL; 1926 1927 return cfqq; 1928} 1929 1930/* 1931 * Determine whether we should enforce idle window for this queue. 1932 */ 1933 1934static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1935{ 1936 enum wl_prio_t prio = cfqq_prio(cfqq); 1937 struct cfq_rb_root *service_tree = cfqq->service_tree; 1938 1939 BUG_ON(!service_tree); 1940 BUG_ON(!service_tree->count); 1941 1942 if (!cfqd->cfq_slice_idle) 1943 return false; 1944 1945 /* We never do for idle class queues. */ 1946 if (prio == IDLE_WORKLOAD) 1947 return false; 1948 1949 /* We do for queues that were marked with idle window flag. */ 1950 if (cfq_cfqq_idle_window(cfqq) && 1951 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 1952 return true; 1953 1954 /* 1955 * Otherwise, we do only if they are the last ones 1956 * in their service tree. 1957 */ 1958 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) 1959 return true; 1960 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 1961 service_tree->count); 1962 return false; 1963} 1964 1965static void cfq_arm_slice_timer(struct cfq_data *cfqd) 1966{ 1967 struct cfq_queue *cfqq = cfqd->active_queue; 1968 struct cfq_io_context *cic; 1969 unsigned long sl, group_idle = 0; 1970 1971 /* 1972 * SSD device without seek penalty, disable idling. But only do so 1973 * for devices that support queuing, otherwise we still have a problem 1974 * with sync vs async workloads. 1975 */ 1976 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 1977 return; 1978 1979 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 1980 WARN_ON(cfq_cfqq_slice_new(cfqq)); 1981 1982 /* 1983 * idle is disabled, either manually or by past process history 1984 */ 1985 if (!cfq_should_idle(cfqd, cfqq)) { 1986 /* no queue idling. Check for group idling */ 1987 if (cfqd->cfq_group_idle) 1988 group_idle = cfqd->cfq_group_idle; 1989 else 1990 return; 1991 } 1992 1993 /* 1994 * still active requests from this queue, don't idle 1995 */ 1996 if (cfqq->dispatched) 1997 return; 1998 1999 /* 2000 * task has exited, don't wait 2001 */ 2002 cic = cfqd->active_cic; 2003 if (!cic || !atomic_read(&cic->ioc->nr_tasks)) 2004 return; 2005 2006 /* 2007 * If our average think time is larger than the remaining time 2008 * slice, then don't idle. This avoids overrunning the allotted 2009 * time slice. 2010 */ 2011 if (sample_valid(cic->ttime_samples) && 2012 (cfqq->slice_end - jiffies < cic->ttime_mean)) { 2013 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2014 cic->ttime_mean); 2015 return; 2016 } 2017 2018 /* There are other queues in the group, don't do group idle */ 2019 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2020 return; 2021 2022 cfq_mark_cfqq_wait_request(cfqq); 2023 2024 if (group_idle) 2025 sl = cfqd->cfq_group_idle; 2026 else 2027 sl = cfqd->cfq_slice_idle; 2028 2029 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2030 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); 2031 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2032 group_idle ? 1 : 0); 2033} 2034 2035/* 2036 * Move request from internal lists to the request queue dispatch list. 2037 */ 2038static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2039{ 2040 struct cfq_data *cfqd = q->elevator->elevator_data; 2041 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2042 2043 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2044 2045 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2046 cfq_remove_request(rq); 2047 cfqq->dispatched++; 2048 (RQ_CFQG(rq))->dispatched++; 2049 elv_dispatch_sort(q, rq); 2050 2051 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2052 cfqq->nr_sectors += blk_rq_sectors(rq); 2053 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), 2054 rq_data_dir(rq), rq_is_sync(rq)); 2055} 2056 2057/* 2058 * return expired entry, or NULL to just start from scratch in rbtree 2059 */ 2060static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2061{ 2062 struct request *rq = NULL; 2063 2064 if (cfq_cfqq_fifo_expire(cfqq)) 2065 return NULL; 2066 2067 cfq_mark_cfqq_fifo_expire(cfqq); 2068 2069 if (list_empty(&cfqq->fifo)) 2070 return NULL; 2071 2072 rq = rq_entry_fifo(cfqq->fifo.next); 2073 if (time_before(jiffies, rq_fifo_time(rq))) 2074 rq = NULL; 2075 2076 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2077 return rq; 2078} 2079 2080static inline int 2081cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2082{ 2083 const int base_rq = cfqd->cfq_slice_async_rq; 2084 2085 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2086 2087 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2088} 2089 2090/* 2091 * Must be called with the queue_lock held. 2092 */ 2093static int cfqq_process_refs(struct cfq_queue *cfqq) 2094{ 2095 int process_refs, io_refs; 2096 2097 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2098 process_refs = cfqq->ref - io_refs; 2099 BUG_ON(process_refs < 0); 2100 return process_refs; 2101} 2102 2103static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2104{ 2105 int process_refs, new_process_refs; 2106 struct cfq_queue *__cfqq; 2107 2108 /* 2109 * If there are no process references on the new_cfqq, then it is 2110 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2111 * chain may have dropped their last reference (not just their 2112 * last process reference). 2113 */ 2114 if (!cfqq_process_refs(new_cfqq)) 2115 return; 2116 2117 /* Avoid a circular list and skip interim queue merges */ 2118 while ((__cfqq = new_cfqq->new_cfqq)) { 2119 if (__cfqq == cfqq) 2120 return; 2121 new_cfqq = __cfqq; 2122 } 2123 2124 process_refs = cfqq_process_refs(cfqq); 2125 new_process_refs = cfqq_process_refs(new_cfqq); 2126 /* 2127 * If the process for the cfqq has gone away, there is no 2128 * sense in merging the queues. 2129 */ 2130 if (process_refs == 0 || new_process_refs == 0) 2131 return; 2132 2133 /* 2134 * Merge in the direction of the lesser amount of work. 2135 */ 2136 if (new_process_refs >= process_refs) { 2137 cfqq->new_cfqq = new_cfqq; 2138 new_cfqq->ref += process_refs; 2139 } else { 2140 new_cfqq->new_cfqq = cfqq; 2141 cfqq->ref += new_process_refs; 2142 } 2143} 2144 2145static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 2146 struct cfq_group *cfqg, enum wl_prio_t prio) 2147{ 2148 struct cfq_queue *queue; 2149 int i; 2150 bool key_valid = false; 2151 unsigned long lowest_key = 0; 2152 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2153 2154 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2155 /* select the one with lowest rb_key */ 2156 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2157 if (queue && 2158 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2159 lowest_key = queue->rb_key; 2160 cur_best = i; 2161 key_valid = true; 2162 } 2163 } 2164 2165 return cur_best; 2166} 2167 2168static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2169{ 2170 unsigned slice; 2171 unsigned count; 2172 struct cfq_rb_root *st; 2173 unsigned group_slice; 2174 enum wl_prio_t original_prio = cfqd->serving_prio; 2175 2176 /* Choose next priority. RT > BE > IDLE */ 2177 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2178 cfqd->serving_prio = RT_WORKLOAD; 2179 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2180 cfqd->serving_prio = BE_WORKLOAD; 2181 else { 2182 cfqd->serving_prio = IDLE_WORKLOAD; 2183 cfqd->workload_expires = jiffies + 1; 2184 return; 2185 } 2186 2187 if (original_prio != cfqd->serving_prio) 2188 goto new_workload; 2189 2190 /* 2191 * For RT and BE, we have to choose also the type 2192 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2193 * expiration time 2194 */ 2195 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2196 count = st->count; 2197 2198 /* 2199 * check workload expiration, and that we still have other queues ready 2200 */ 2201 if (count && !time_after(jiffies, cfqd->workload_expires)) 2202 return; 2203 2204new_workload: 2205 /* otherwise select new workload type */ 2206 cfqd->serving_type = 2207 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2208 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2209 count = st->count; 2210 2211 /* 2212 * the workload slice is computed as a fraction of target latency 2213 * proportional to the number of queues in that workload, over 2214 * all the queues in the same priority class 2215 */ 2216 group_slice = cfq_group_slice(cfqd, cfqg); 2217 2218 slice = group_slice * count / 2219 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2220 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2221 2222 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2223 unsigned int tmp; 2224 2225 /* 2226 * Async queues are currently system wide. Just taking 2227 * proportion of queues with-in same group will lead to higher 2228 * async ratio system wide as generally root group is going 2229 * to have higher weight. A more accurate thing would be to 2230 * calculate system wide asnc/sync ratio. 2231 */ 2232 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2233 tmp = tmp/cfqd->busy_queues; 2234 slice = min_t(unsigned, slice, tmp); 2235 2236 /* async workload slice is scaled down according to 2237 * the sync/async slice ratio. */ 2238 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2239 } else 2240 /* sync workload slice is at least 2 * cfq_slice_idle */ 2241 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2242 2243 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2244 cfq_log(cfqd, "workload slice:%d", slice); 2245 cfqd->workload_expires = jiffies + slice; 2246} 2247 2248static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2249{ 2250 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2251 struct cfq_group *cfqg; 2252 2253 if (RB_EMPTY_ROOT(&st->rb)) 2254 return NULL; 2255 cfqg = cfq_rb_first_group(st); 2256 update_min_vdisktime(st); 2257 return cfqg; 2258} 2259 2260static void cfq_choose_cfqg(struct cfq_data *cfqd) 2261{ 2262 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2263 2264 cfqd->serving_group = cfqg; 2265 2266 /* Restore the workload type data */ 2267 if (cfqg->saved_workload_slice) { 2268 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2269 cfqd->serving_type = cfqg->saved_workload; 2270 cfqd->serving_prio = cfqg->saved_serving_prio; 2271 } else 2272 cfqd->workload_expires = jiffies - 1; 2273 2274 choose_service_tree(cfqd, cfqg); 2275} 2276 2277/* 2278 * Select a queue for service. If we have a current active queue, 2279 * check whether to continue servicing it, or retrieve and set a new one. 2280 */ 2281static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2282{ 2283 struct cfq_queue *cfqq, *new_cfqq = NULL; 2284 2285 cfqq = cfqd->active_queue; 2286 if (!cfqq) 2287 goto new_queue; 2288 2289 if (!cfqd->rq_queued) 2290 return NULL; 2291 2292 /* 2293 * We were waiting for group to get backlogged. Expire the queue 2294 */ 2295 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2296 goto expire; 2297 2298 /* 2299 * The active queue has run out of time, expire it and select new. 2300 */ 2301 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2302 /* 2303 * If slice had not expired at the completion of last request 2304 * we might not have turned on wait_busy flag. Don't expire 2305 * the queue yet. Allow the group to get backlogged. 2306 * 2307 * The very fact that we have used the slice, that means we 2308 * have been idling all along on this queue and it should be 2309 * ok to wait for this request to complete. 2310 */ 2311 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2312 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2313 cfqq = NULL; 2314 goto keep_queue; 2315 } else 2316 goto check_group_idle; 2317 } 2318 2319 /* 2320 * The active queue has requests and isn't expired, allow it to 2321 * dispatch. 2322 */ 2323 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2324 goto keep_queue; 2325 2326 /* 2327 * If another queue has a request waiting within our mean seek 2328 * distance, let it run. The expire code will check for close 2329 * cooperators and put the close queue at the front of the service 2330 * tree. If possible, merge the expiring queue with the new cfqq. 2331 */ 2332 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2333 if (new_cfqq) { 2334 if (!cfqq->new_cfqq) 2335 cfq_setup_merge(cfqq, new_cfqq); 2336 goto expire; 2337 } 2338 2339 /* 2340 * No requests pending. If the active queue still has requests in 2341 * flight or is idling for a new request, allow either of these 2342 * conditions to happen (or time out) before selecting a new queue. 2343 */ 2344 if (timer_pending(&cfqd->idle_slice_timer)) { 2345 cfqq = NULL; 2346 goto keep_queue; 2347 } 2348 2349 /* 2350 * This is a deep seek queue, but the device is much faster than 2351 * the queue can deliver, don't idle 2352 **/ 2353 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2354 (cfq_cfqq_slice_new(cfqq) || 2355 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2356 cfq_clear_cfqq_deep(cfqq); 2357 cfq_clear_cfqq_idle_window(cfqq); 2358 } 2359 2360 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2361 cfqq = NULL; 2362 goto keep_queue; 2363 } 2364 2365 /* 2366 * If group idle is enabled and there are requests dispatched from 2367 * this group, wait for requests to complete. 2368 */ 2369check_group_idle: 2370 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 2371 && cfqq->cfqg->dispatched) { 2372 cfqq = NULL; 2373 goto keep_queue; 2374 } 2375 2376expire: 2377 cfq_slice_expired(cfqd, 0); 2378new_queue: 2379 /* 2380 * Current queue expired. Check if we have to switch to a new 2381 * service tree 2382 */ 2383 if (!new_cfqq) 2384 cfq_choose_cfqg(cfqd); 2385 2386 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2387keep_queue: 2388 return cfqq; 2389} 2390 2391static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2392{ 2393 int dispatched = 0; 2394 2395 while (cfqq->next_rq) { 2396 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2397 dispatched++; 2398 } 2399 2400 BUG_ON(!list_empty(&cfqq->fifo)); 2401 2402 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2403 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2404 return dispatched; 2405} 2406 2407/* 2408 * Drain our current requests. Used for barriers and when switching 2409 * io schedulers on-the-fly. 2410 */ 2411static int cfq_forced_dispatch(struct cfq_data *cfqd) 2412{ 2413 struct cfq_queue *cfqq; 2414 int dispatched = 0; 2415 2416 /* Expire the timeslice of the current active queue first */ 2417 cfq_slice_expired(cfqd, 0); 2418 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2419 __cfq_set_active_queue(cfqd, cfqq); 2420 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2421 } 2422 2423 BUG_ON(cfqd->busy_queues); 2424 2425 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2426 return dispatched; 2427} 2428 2429static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2430 struct cfq_queue *cfqq) 2431{ 2432 /* the queue hasn't finished any request, can't estimate */ 2433 if (cfq_cfqq_slice_new(cfqq)) 2434 return true; 2435 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2436 cfqq->slice_end)) 2437 return true; 2438 2439 return false; 2440} 2441 2442static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2443{ 2444 unsigned int max_dispatch; 2445 2446 /* 2447 * Drain async requests before we start sync IO 2448 */ 2449 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2450 return false; 2451 2452 /* 2453 * If this is an async queue and we have sync IO in flight, let it wait 2454 */ 2455 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2456 return false; 2457 2458 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2459 if (cfq_class_idle(cfqq)) 2460 max_dispatch = 1; 2461 2462 /* 2463 * Does this cfqq already have too much IO in flight? 2464 */ 2465 if (cfqq->dispatched >= max_dispatch) { 2466 bool promote_sync = false; 2467 /* 2468 * idle queue must always only have a single IO in flight 2469 */ 2470 if (cfq_class_idle(cfqq)) 2471 return false; 2472 2473 /* 2474 * If there is only one sync queue 2475 * we can ignore async queue here and give the sync 2476 * queue no dispatch limit. The reason is a sync queue can 2477 * preempt async queue, limiting the sync queue doesn't make 2478 * sense. This is useful for aiostress test. 2479 */ 2480 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2481 promote_sync = true; 2482 2483 /* 2484 * We have other queues, don't allow more IO from this one 2485 */ 2486 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2487 !promote_sync) 2488 return false; 2489 2490 /* 2491 * Sole queue user, no limit 2492 */ 2493 if (cfqd->busy_queues == 1 || promote_sync) 2494 max_dispatch = -1; 2495 else 2496 /* 2497 * Normally we start throttling cfqq when cfq_quantum/2 2498 * requests have been dispatched. But we can drive 2499 * deeper queue depths at the beginning of slice 2500 * subjected to upper limit of cfq_quantum. 2501 * */ 2502 max_dispatch = cfqd->cfq_quantum; 2503 } 2504 2505 /* 2506 * Async queues must wait a bit before being allowed dispatch. 2507 * We also ramp up the dispatch depth gradually for async IO, 2508 * based on the last sync IO we serviced 2509 */ 2510 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2511 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2512 unsigned int depth; 2513 2514 depth = last_sync / cfqd->cfq_slice[1]; 2515 if (!depth && !cfqq->dispatched) 2516 depth = 1; 2517 if (depth < max_dispatch) 2518 max_dispatch = depth; 2519 } 2520 2521 /* 2522 * If we're below the current max, allow a dispatch 2523 */ 2524 return cfqq->dispatched < max_dispatch; 2525} 2526 2527/* 2528 * Dispatch a request from cfqq, moving them to the request queue 2529 * dispatch list. 2530 */ 2531static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2532{ 2533 struct request *rq; 2534 2535 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2536 2537 if (!cfq_may_dispatch(cfqd, cfqq)) 2538 return false; 2539 2540 /* 2541 * follow expired path, else get first next available 2542 */ 2543 rq = cfq_check_fifo(cfqq); 2544 if (!rq) 2545 rq = cfqq->next_rq; 2546 2547 /* 2548 * insert request into driver dispatch list 2549 */ 2550 cfq_dispatch_insert(cfqd->queue, rq); 2551 2552 if (!cfqd->active_cic) { 2553 struct cfq_io_context *cic = RQ_CIC(rq); 2554 2555 atomic_long_inc(&cic->ioc->refcount); 2556 cfqd->active_cic = cic; 2557 } 2558 2559 return true; 2560} 2561 2562/* 2563 * Find the cfqq that we need to service and move a request from that to the 2564 * dispatch list 2565 */ 2566static int cfq_dispatch_requests(struct request_queue *q, int force) 2567{ 2568 struct cfq_data *cfqd = q->elevator->elevator_data; 2569 struct cfq_queue *cfqq; 2570 2571 if (!cfqd->busy_queues) 2572 return 0; 2573 2574 if (unlikely(force)) 2575 return cfq_forced_dispatch(cfqd); 2576 2577 cfqq = cfq_select_queue(cfqd); 2578 if (!cfqq) 2579 return 0; 2580 2581 /* 2582 * Dispatch a request from this cfqq, if it is allowed 2583 */ 2584 if (!cfq_dispatch_request(cfqd, cfqq)) 2585 return 0; 2586 2587 cfqq->slice_dispatch++; 2588 cfq_clear_cfqq_must_dispatch(cfqq); 2589 2590 /* 2591 * expire an async queue immediately if it has used up its slice. idle 2592 * queue always expire after 1 dispatch round. 2593 */ 2594 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2595 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2596 cfq_class_idle(cfqq))) { 2597 cfqq->slice_end = jiffies + 1; 2598 cfq_slice_expired(cfqd, 0); 2599 } 2600 2601 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2602 return 1; 2603} 2604 2605/* 2606 * task holds one reference to the queue, dropped when task exits. each rq 2607 * in-flight on this queue also holds a reference, dropped when rq is freed. 2608 * 2609 * Each cfq queue took a reference on the parent group. Drop it now. 2610 * queue lock must be held here. 2611 */ 2612static void cfq_put_queue(struct cfq_queue *cfqq) 2613{ 2614 struct cfq_data *cfqd = cfqq->cfqd; 2615 struct cfq_group *cfqg; 2616 2617 BUG_ON(cfqq->ref <= 0); 2618 2619 cfqq->ref--; 2620 if (cfqq->ref) 2621 return; 2622 2623 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2624 BUG_ON(rb_first(&cfqq->sort_list)); 2625 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2626 cfqg = cfqq->cfqg; 2627 2628 if (unlikely(cfqd->active_queue == cfqq)) { 2629 __cfq_slice_expired(cfqd, cfqq, 0); 2630 cfq_schedule_dispatch(cfqd); 2631 } 2632 2633 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2634 kmem_cache_free(cfq_pool, cfqq); 2635 cfq_put_cfqg(cfqg); 2636} 2637 2638/* 2639 * Call func for each cic attached to this ioc. 2640 */ 2641static void 2642call_for_each_cic(struct io_context *ioc, 2643 void (*func)(struct io_context *, struct cfq_io_context *)) 2644{ 2645 struct cfq_io_context *cic; 2646 struct hlist_node *n; 2647 2648 rcu_read_lock(); 2649 2650 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) 2651 func(ioc, cic); 2652 2653 rcu_read_unlock(); 2654} 2655 2656static void cfq_cic_free_rcu(struct rcu_head *head) 2657{ 2658 struct cfq_io_context *cic; 2659 2660 cic = container_of(head, struct cfq_io_context, rcu_head); 2661 2662 kmem_cache_free(cfq_ioc_pool, cic); 2663 elv_ioc_count_dec(cfq_ioc_count); 2664 2665 if (ioc_gone) { 2666 /* 2667 * CFQ scheduler is exiting, grab exit lock and check 2668 * the pending io context count. If it hits zero, 2669 * complete ioc_gone and set it back to NULL 2670 */ 2671 spin_lock(&ioc_gone_lock); 2672 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { 2673 complete(ioc_gone); 2674 ioc_gone = NULL; 2675 } 2676 spin_unlock(&ioc_gone_lock); 2677 } 2678} 2679 2680static void cfq_cic_free(struct cfq_io_context *cic) 2681{ 2682 call_rcu(&cic->rcu_head, cfq_cic_free_rcu); 2683} 2684 2685static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) 2686{ 2687 unsigned long flags; 2688 unsigned long dead_key = (unsigned long) cic->key; 2689 2690 BUG_ON(!(dead_key & CIC_DEAD_KEY)); 2691 2692 spin_lock_irqsave(&ioc->lock, flags); 2693 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); 2694 hlist_del_rcu(&cic->cic_list); 2695 spin_unlock_irqrestore(&ioc->lock, flags); 2696 2697 cfq_cic_free(cic); 2698} 2699 2700/* 2701 * Must be called with rcu_read_lock() held or preemption otherwise disabled. 2702 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), 2703 * and ->trim() which is called with the task lock held 2704 */ 2705static void cfq_free_io_context(struct io_context *ioc) 2706{ 2707 /* 2708 * ioc->refcount is zero here, or we are called from elv_unregister(), 2709 * so no more cic's are allowed to be linked into this ioc. So it 2710 * should be ok to iterate over the known list, we will see all cic's 2711 * since no new ones are added. 2712 */ 2713 call_for_each_cic(ioc, cic_free_func); 2714} 2715 2716static void cfq_put_cooperator(struct cfq_queue *cfqq) 2717{ 2718 struct cfq_queue *__cfqq, *next; 2719 2720 /* 2721 * If this queue was scheduled to merge with another queue, be 2722 * sure to drop the reference taken on that queue (and others in 2723 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2724 */ 2725 __cfqq = cfqq->new_cfqq; 2726 while (__cfqq) { 2727 if (__cfqq == cfqq) { 2728 WARN(1, "cfqq->new_cfqq loop detected\n"); 2729 break; 2730 } 2731 next = __cfqq->new_cfqq; 2732 cfq_put_queue(__cfqq); 2733 __cfqq = next; 2734 } 2735} 2736 2737static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2738{ 2739 if (unlikely(cfqq == cfqd->active_queue)) { 2740 __cfq_slice_expired(cfqd, cfqq, 0); 2741 cfq_schedule_dispatch(cfqd); 2742 } 2743 2744 cfq_put_cooperator(cfqq); 2745 2746 cfq_put_queue(cfqq); 2747} 2748 2749static void __cfq_exit_single_io_context(struct cfq_data *cfqd, 2750 struct cfq_io_context *cic) 2751{ 2752 struct io_context *ioc = cic->ioc; 2753 2754 list_del_init(&cic->queue_list); 2755 2756 /* 2757 * Make sure dead mark is seen for dead queues 2758 */ 2759 smp_wmb(); 2760 cic->key = cfqd_dead_key(cfqd); 2761 2762 rcu_read_lock(); 2763 if (rcu_dereference(ioc->ioc_data) == cic) { 2764 rcu_read_unlock(); 2765 spin_lock(&ioc->lock); 2766 rcu_assign_pointer(ioc->ioc_data, NULL); 2767 spin_unlock(&ioc->lock); 2768 } else 2769 rcu_read_unlock(); 2770 2771 if (cic->cfqq[BLK_RW_ASYNC]) { 2772 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2773 cic->cfqq[BLK_RW_ASYNC] = NULL; 2774 } 2775 2776 if (cic->cfqq[BLK_RW_SYNC]) { 2777 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2778 cic->cfqq[BLK_RW_SYNC] = NULL; 2779 } 2780} 2781 2782static void cfq_exit_single_io_context(struct io_context *ioc, 2783 struct cfq_io_context *cic) 2784{ 2785 struct cfq_data *cfqd = cic_to_cfqd(cic); 2786 2787 if (cfqd) { 2788 struct request_queue *q = cfqd->queue; 2789 unsigned long flags; 2790 2791 spin_lock_irqsave(q->queue_lock, flags); 2792 2793 /* 2794 * Ensure we get a fresh copy of the ->key to prevent 2795 * race between exiting task and queue 2796 */ 2797 smp_read_barrier_depends(); 2798 if (cic->key == cfqd) 2799 __cfq_exit_single_io_context(cfqd, cic); 2800 2801 spin_unlock_irqrestore(q->queue_lock, flags); 2802 } 2803} 2804 2805/* 2806 * The process that ioc belongs to has exited, we need to clean up 2807 * and put the internal structures we have that belongs to that process. 2808 */ 2809static void cfq_exit_io_context(struct io_context *ioc) 2810{ 2811 call_for_each_cic(ioc, cfq_exit_single_io_context); 2812} 2813 2814static struct cfq_io_context * 2815cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2816{ 2817 struct cfq_io_context *cic; 2818 2819 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, 2820 cfqd->queue->node); 2821 if (cic) { 2822 cic->last_end_request = jiffies; 2823 INIT_LIST_HEAD(&cic->queue_list); 2824 INIT_HLIST_NODE(&cic->cic_list); 2825 cic->dtor = cfq_free_io_context; 2826 cic->exit = cfq_exit_io_context; 2827 elv_ioc_count_inc(cfq_ioc_count); 2828 } 2829 2830 return cic; 2831} 2832 2833static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2834{ 2835 struct task_struct *tsk = current; 2836 int ioprio_class; 2837 2838 if (!cfq_cfqq_prio_changed(cfqq)) 2839 return; 2840 2841 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2842 switch (ioprio_class) { 2843 default: 2844 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2845 case IOPRIO_CLASS_NONE: 2846 /* 2847 * no prio set, inherit CPU scheduling settings 2848 */ 2849 cfqq->ioprio = task_nice_ioprio(tsk); 2850 cfqq->ioprio_class = task_nice_ioclass(tsk); 2851 break; 2852 case IOPRIO_CLASS_RT: 2853 cfqq->ioprio = task_ioprio(ioc); 2854 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2855 break; 2856 case IOPRIO_CLASS_BE: 2857 cfqq->ioprio = task_ioprio(ioc); 2858 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2859 break; 2860 case IOPRIO_CLASS_IDLE: 2861 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2862 cfqq->ioprio = 7; 2863 cfq_clear_cfqq_idle_window(cfqq); 2864 break; 2865 } 2866 2867 /* 2868 * keep track of original prio settings in case we have to temporarily 2869 * elevate the priority of this queue 2870 */ 2871 cfqq->org_ioprio = cfqq->ioprio; 2872 cfq_clear_cfqq_prio_changed(cfqq); 2873} 2874 2875static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) 2876{ 2877 struct cfq_data *cfqd = cic_to_cfqd(cic); 2878 struct cfq_queue *cfqq; 2879 unsigned long flags; 2880 2881 if (unlikely(!cfqd)) 2882 return; 2883 2884 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2885 2886 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2887 if (cfqq) { 2888 struct cfq_queue *new_cfqq; 2889 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, 2890 GFP_ATOMIC); 2891 if (new_cfqq) { 2892 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2893 cfq_put_queue(cfqq); 2894 } 2895 } 2896 2897 cfqq = cic->cfqq[BLK_RW_SYNC]; 2898 if (cfqq) 2899 cfq_mark_cfqq_prio_changed(cfqq); 2900 2901 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2902} 2903 2904static void cfq_ioc_set_ioprio(struct io_context *ioc) 2905{ 2906 call_for_each_cic(ioc, changed_ioprio); 2907 ioc->ioprio_changed = 0; 2908} 2909 2910static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2911 pid_t pid, bool is_sync) 2912{ 2913 RB_CLEAR_NODE(&cfqq->rb_node); 2914 RB_CLEAR_NODE(&cfqq->p_node); 2915 INIT_LIST_HEAD(&cfqq->fifo); 2916 2917 cfqq->ref = 0; 2918 cfqq->cfqd = cfqd; 2919 2920 cfq_mark_cfqq_prio_changed(cfqq); 2921 2922 if (is_sync) { 2923 if (!cfq_class_idle(cfqq)) 2924 cfq_mark_cfqq_idle_window(cfqq); 2925 cfq_mark_cfqq_sync(cfqq); 2926 } 2927 cfqq->pid = pid; 2928} 2929 2930#ifdef CONFIG_CFQ_GROUP_IOSCHED 2931static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) 2932{ 2933 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2934 struct cfq_data *cfqd = cic_to_cfqd(cic); 2935 unsigned long flags; 2936 struct request_queue *q; 2937 2938 if (unlikely(!cfqd)) 2939 return; 2940 2941 q = cfqd->queue; 2942 2943 spin_lock_irqsave(q->queue_lock, flags); 2944 2945 if (sync_cfqq) { 2946 /* 2947 * Drop reference to sync queue. A new sync queue will be 2948 * assigned in new group upon arrival of a fresh request. 2949 */ 2950 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2951 cic_set_cfqq(cic, NULL, 1); 2952 cfq_put_queue(sync_cfqq); 2953 } 2954 2955 spin_unlock_irqrestore(q->queue_lock, flags); 2956} 2957 2958static void cfq_ioc_set_cgroup(struct io_context *ioc) 2959{ 2960 call_for_each_cic(ioc, changed_cgroup); 2961 ioc->cgroup_changed = 0; 2962} 2963#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2964 2965static struct cfq_queue * 2966cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2967 struct io_context *ioc, gfp_t gfp_mask) 2968{ 2969 struct cfq_queue *cfqq, *new_cfqq = NULL; 2970 struct cfq_io_context *cic; 2971 struct cfq_group *cfqg; 2972 2973retry: 2974 cfqg = cfq_get_cfqg(cfqd); 2975 cic = cfq_cic_lookup(cfqd, ioc); 2976 /* cic always exists here */ 2977 cfqq = cic_to_cfqq(cic, is_sync); 2978 2979 /* 2980 * Always try a new alloc if we fell back to the OOM cfqq 2981 * originally, since it should just be a temporary situation. 2982 */ 2983 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 2984 cfqq = NULL; 2985 if (new_cfqq) { 2986 cfqq = new_cfqq; 2987 new_cfqq = NULL; 2988 } else if (gfp_mask & __GFP_WAIT) { 2989 spin_unlock_irq(cfqd->queue->queue_lock); 2990 new_cfqq = kmem_cache_alloc_node(cfq_pool, 2991 gfp_mask | __GFP_ZERO, 2992 cfqd->queue->node); 2993 spin_lock_irq(cfqd->queue->queue_lock); 2994 if (new_cfqq) 2995 goto retry; 2996 } else { 2997 cfqq = kmem_cache_alloc_node(cfq_pool, 2998 gfp_mask | __GFP_ZERO, 2999 cfqd->queue->node); 3000 } 3001 3002 if (cfqq) { 3003 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3004 cfq_init_prio_data(cfqq, ioc); 3005 cfq_link_cfqq_cfqg(cfqq, cfqg); 3006 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3007 } else 3008 cfqq = &cfqd->oom_cfqq; 3009 } 3010 3011 if (new_cfqq) 3012 kmem_cache_free(cfq_pool, new_cfqq); 3013 3014 return cfqq; 3015} 3016 3017static struct cfq_queue ** 3018cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3019{ 3020 switch (ioprio_class) { 3021 case IOPRIO_CLASS_RT: 3022 return &cfqd->async_cfqq[0][ioprio]; 3023 case IOPRIO_CLASS_BE: 3024 return &cfqd->async_cfqq[1][ioprio]; 3025 case IOPRIO_CLASS_IDLE: 3026 return &cfqd->async_idle_cfqq; 3027 default: 3028 BUG(); 3029 } 3030} 3031 3032static struct cfq_queue * 3033cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 3034 gfp_t gfp_mask) 3035{ 3036 const int ioprio = task_ioprio(ioc); 3037 const int ioprio_class = task_ioprio_class(ioc); 3038 struct cfq_queue **async_cfqq = NULL; 3039 struct cfq_queue *cfqq = NULL; 3040 3041 if (!is_sync) { 3042 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3043 cfqq = *async_cfqq; 3044 } 3045 3046 if (!cfqq) 3047 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 3048 3049 /* 3050 * pin the queue now that it's allocated, scheduler exit will prune it 3051 */ 3052 if (!is_sync && !(*async_cfqq)) { 3053 cfqq->ref++; 3054 *async_cfqq = cfqq; 3055 } 3056 3057 cfqq->ref++; 3058 return cfqq; 3059} 3060 3061/* 3062 * We drop cfq io contexts lazily, so we may find a dead one. 3063 */ 3064static void 3065cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, 3066 struct cfq_io_context *cic) 3067{ 3068 unsigned long flags; 3069 3070 WARN_ON(!list_empty(&cic->queue_list)); 3071 BUG_ON(cic->key != cfqd_dead_key(cfqd)); 3072 3073 spin_lock_irqsave(&ioc->lock, flags); 3074 3075 BUG_ON(rcu_dereference_check(ioc->ioc_data, 3076 lockdep_is_held(&ioc->lock)) == cic); 3077 3078 radix_tree_delete(&ioc->radix_root, cfqd->cic_index); 3079 hlist_del_rcu(&cic->cic_list); 3080 spin_unlock_irqrestore(&ioc->lock, flags); 3081 3082 cfq_cic_free(cic); 3083} 3084 3085static struct cfq_io_context * 3086cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) 3087{ 3088 struct cfq_io_context *cic; 3089 unsigned long flags; 3090 3091 if (unlikely(!ioc)) 3092 return NULL; 3093 3094 rcu_read_lock(); 3095 3096 /* 3097 * we maintain a last-hit cache, to avoid browsing over the tree 3098 */ 3099 cic = rcu_dereference(ioc->ioc_data); 3100 if (cic && cic->key == cfqd) { 3101 rcu_read_unlock(); 3102 return cic; 3103 } 3104 3105 do { 3106 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); 3107 rcu_read_unlock(); 3108 if (!cic) 3109 break; 3110 if (unlikely(cic->key != cfqd)) { 3111 cfq_drop_dead_cic(cfqd, ioc, cic); 3112 rcu_read_lock(); 3113 continue; 3114 } 3115 3116 spin_lock_irqsave(&ioc->lock, flags); 3117 rcu_assign_pointer(ioc->ioc_data, cic); 3118 spin_unlock_irqrestore(&ioc->lock, flags); 3119 break; 3120 } while (1); 3121 3122 return cic; 3123} 3124 3125/* 3126 * Add cic into ioc, using cfqd as the search key. This enables us to lookup 3127 * the process specific cfq io context when entered from the block layer. 3128 * Also adds the cic to a per-cfqd list, used when this queue is removed. 3129 */ 3130static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, 3131 struct cfq_io_context *cic, gfp_t gfp_mask) 3132{ 3133 unsigned long flags; 3134 int ret; 3135 3136 ret = radix_tree_preload(gfp_mask); 3137 if (!ret) { 3138 cic->ioc = ioc; 3139 cic->key = cfqd; 3140 3141 spin_lock_irqsave(&ioc->lock, flags); 3142 ret = radix_tree_insert(&ioc->radix_root, 3143 cfqd->cic_index, cic); 3144 if (!ret) 3145 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); 3146 spin_unlock_irqrestore(&ioc->lock, flags); 3147 3148 radix_tree_preload_end(); 3149 3150 if (!ret) { 3151 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3152 list_add(&cic->queue_list, &cfqd->cic_list); 3153 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3154 } 3155 } 3156 3157 if (ret) 3158 printk(KERN_ERR "cfq: cic link failed!\n"); 3159 3160 return ret; 3161} 3162 3163/* 3164 * Setup general io context and cfq io context. There can be several cfq 3165 * io contexts per general io context, if this process is doing io to more 3166 * than one device managed by cfq. 3167 */ 3168static struct cfq_io_context * 3169cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 3170{ 3171 struct io_context *ioc = NULL; 3172 struct cfq_io_context *cic; 3173 3174 might_sleep_if(gfp_mask & __GFP_WAIT); 3175 3176 ioc = get_io_context(gfp_mask, cfqd->queue->node); 3177 if (!ioc) 3178 return NULL; 3179 3180 cic = cfq_cic_lookup(cfqd, ioc); 3181 if (cic) 3182 goto out; 3183 3184 cic = cfq_alloc_io_context(cfqd, gfp_mask); 3185 if (cic == NULL) 3186 goto err; 3187 3188 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) 3189 goto err_free; 3190 3191out: 3192 smp_read_barrier_depends(); 3193 if (unlikely(ioc->ioprio_changed)) 3194 cfq_ioc_set_ioprio(ioc); 3195 3196#ifdef CONFIG_CFQ_GROUP_IOSCHED 3197 if (unlikely(ioc->cgroup_changed)) 3198 cfq_ioc_set_cgroup(ioc); 3199#endif 3200 return cic; 3201err_free: 3202 cfq_cic_free(cic); 3203err: 3204 put_io_context(ioc); 3205 return NULL; 3206} 3207 3208static void 3209cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) 3210{ 3211 unsigned long elapsed = jiffies - cic->last_end_request; 3212 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); 3213 3214 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; 3215 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; 3216 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; 3217} 3218 3219static void 3220cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3221 struct request *rq) 3222{ 3223 sector_t sdist = 0; 3224 sector_t n_sec = blk_rq_sectors(rq); 3225 if (cfqq->last_request_pos) { 3226 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3227 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3228 else 3229 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3230 } 3231 3232 cfqq->seek_history <<= 1; 3233 if (blk_queue_nonrot(cfqd->queue)) 3234 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3235 else 3236 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3237} 3238 3239/* 3240 * Disable idle window if the process thinks too long or seeks so much that 3241 * it doesn't matter 3242 */ 3243static void 3244cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3245 struct cfq_io_context *cic) 3246{ 3247 int old_idle, enable_idle; 3248 3249 /* 3250 * Don't idle for async or idle io prio class 3251 */ 3252 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3253 return; 3254 3255 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3256 3257 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3258 cfq_mark_cfqq_deep(cfqq); 3259 3260 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3261 enable_idle = 0; 3262 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || 3263 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3264 enable_idle = 0; 3265 else if (sample_valid(cic->ttime_samples)) { 3266 if (cic->ttime_mean > cfqd->cfq_slice_idle) 3267 enable_idle = 0; 3268 else 3269 enable_idle = 1; 3270 } 3271 3272 if (old_idle != enable_idle) { 3273 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3274 if (enable_idle) 3275 cfq_mark_cfqq_idle_window(cfqq); 3276 else 3277 cfq_clear_cfqq_idle_window(cfqq); 3278 } 3279} 3280 3281/* 3282 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3283 * no or if we aren't sure, a 1 will cause a preempt. 3284 */ 3285static bool 3286cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3287 struct request *rq) 3288{ 3289 struct cfq_queue *cfqq; 3290 3291 cfqq = cfqd->active_queue; 3292 if (!cfqq) 3293 return false; 3294 3295 if (cfq_class_idle(new_cfqq)) 3296 return false; 3297 3298 if (cfq_class_idle(cfqq)) 3299 return true; 3300 3301 /* 3302 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3303 */ 3304 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3305 return false; 3306 3307 /* 3308 * if the new request is sync, but the currently running queue is 3309 * not, let the sync request have priority. 3310 */ 3311 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3312 return true; 3313 3314 if (new_cfqq->cfqg != cfqq->cfqg) 3315 return false; 3316 3317 if (cfq_slice_used(cfqq)) 3318 return true; 3319 3320 /* Allow preemption only if we are idling on sync-noidle tree */ 3321 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3322 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3323 new_cfqq->service_tree->count == 2 && 3324 RB_EMPTY_ROOT(&cfqq->sort_list)) 3325 return true; 3326 3327 /* 3328 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3329 */ 3330 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3331 return true; 3332 3333 /* An idle queue should not be idle now for some reason */ 3334 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3335 return true; 3336 3337 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3338 return false; 3339 3340 /* 3341 * if this request is as-good as one we would expect from the 3342 * current cfqq, let it preempt 3343 */ 3344 if (cfq_rq_close(cfqd, cfqq, rq)) 3345 return true; 3346 3347 return false; 3348} 3349 3350/* 3351 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3352 * let it have half of its nominal slice. 3353 */ 3354static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3355{ 3356 struct cfq_queue *old_cfqq = cfqd->active_queue; 3357 3358 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3359 cfq_slice_expired(cfqd, 1); 3360 3361 /* 3362 * workload type is changed, don't save slice, otherwise preempt 3363 * doesn't happen 3364 */ 3365 if (cfqq_type(old_cfqq) != cfqq_type(cfqq)) 3366 cfqq->cfqg->saved_workload_slice = 0; 3367 3368 /* 3369 * Put the new queue at the front of the of the current list, 3370 * so we know that it will be selected next. 3371 */ 3372 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3373 3374 cfq_service_tree_add(cfqd, cfqq, 1); 3375 3376 cfqq->slice_end = 0; 3377 cfq_mark_cfqq_slice_new(cfqq); 3378} 3379 3380/* 3381 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3382 * something we should do about it 3383 */ 3384static void 3385cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3386 struct request *rq) 3387{ 3388 struct cfq_io_context *cic = RQ_CIC(rq); 3389 3390 cfqd->rq_queued++; 3391 3392 cfq_update_io_thinktime(cfqd, cic); 3393 cfq_update_io_seektime(cfqd, cfqq, rq); 3394 cfq_update_idle_window(cfqd, cfqq, cic); 3395 3396 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3397 3398 if (cfqq == cfqd->active_queue) { 3399 /* 3400 * Remember that we saw a request from this process, but 3401 * don't start queuing just yet. Otherwise we risk seeing lots 3402 * of tiny requests, because we disrupt the normal plugging 3403 * and merging. If the request is already larger than a single 3404 * page, let it rip immediately. For that case we assume that 3405 * merging is already done. Ditto for a busy system that 3406 * has other work pending, don't risk delaying until the 3407 * idle timer unplug to continue working. 3408 */ 3409 if (cfq_cfqq_wait_request(cfqq)) { 3410 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3411 cfqd->busy_queues > 1) { 3412 cfq_del_timer(cfqd, cfqq); 3413 cfq_clear_cfqq_wait_request(cfqq); 3414 __blk_run_queue(cfqd->queue); 3415 } else { 3416 cfq_blkiocg_update_idle_time_stats( 3417 &cfqq->cfqg->blkg); 3418 cfq_mark_cfqq_must_dispatch(cfqq); 3419 } 3420 } 3421 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3422 /* 3423 * not the active queue - expire current slice if it is 3424 * idle and has expired it's mean thinktime or this new queue 3425 * has some old slice time left and is of higher priority or 3426 * this new queue is RT and the current one is BE 3427 */ 3428 cfq_preempt_queue(cfqd, cfqq); 3429 __blk_run_queue(cfqd->queue); 3430 } 3431} 3432 3433static void cfq_insert_request(struct request_queue *q, struct request *rq) 3434{ 3435 struct cfq_data *cfqd = q->elevator->elevator_data; 3436 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3437 3438 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3439 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); 3440 3441 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3442 list_add_tail(&rq->queuelist, &cfqq->fifo); 3443 cfq_add_rq_rb(rq); 3444 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 3445 &cfqd->serving_group->blkg, rq_data_dir(rq), 3446 rq_is_sync(rq)); 3447 cfq_rq_enqueued(cfqd, cfqq, rq); 3448} 3449 3450/* 3451 * Update hw_tag based on peak queue depth over 50 samples under 3452 * sufficient load. 3453 */ 3454static void cfq_update_hw_tag(struct cfq_data *cfqd) 3455{ 3456 struct cfq_queue *cfqq = cfqd->active_queue; 3457 3458 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3459 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3460 3461 if (cfqd->hw_tag == 1) 3462 return; 3463 3464 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3465 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3466 return; 3467 3468 /* 3469 * If active queue hasn't enough requests and can idle, cfq might not 3470 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3471 * case 3472 */ 3473 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3474 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3475 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3476 return; 3477 3478 if (cfqd->hw_tag_samples++ < 50) 3479 return; 3480 3481 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3482 cfqd->hw_tag = 1; 3483 else 3484 cfqd->hw_tag = 0; 3485} 3486 3487static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3488{ 3489 struct cfq_io_context *cic = cfqd->active_cic; 3490 3491 /* If the queue already has requests, don't wait */ 3492 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3493 return false; 3494 3495 /* If there are other queues in the group, don't wait */ 3496 if (cfqq->cfqg->nr_cfqq > 1) 3497 return false; 3498 3499 if (cfq_slice_used(cfqq)) 3500 return true; 3501 3502 /* if slice left is less than think time, wait busy */ 3503 if (cic && sample_valid(cic->ttime_samples) 3504 && (cfqq->slice_end - jiffies < cic->ttime_mean)) 3505 return true; 3506 3507 /* 3508 * If think times is less than a jiffy than ttime_mean=0 and above 3509 * will not be true. It might happen that slice has not expired yet 3510 * but will expire soon (4-5 ns) during select_queue(). To cover the 3511 * case where think time is less than a jiffy, mark the queue wait 3512 * busy if only 1 jiffy is left in the slice. 3513 */ 3514 if (cfqq->slice_end - jiffies == 1) 3515 return true; 3516 3517 return false; 3518} 3519 3520static void cfq_completed_request(struct request_queue *q, struct request *rq) 3521{ 3522 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3523 struct cfq_data *cfqd = cfqq->cfqd; 3524 const int sync = rq_is_sync(rq); 3525 unsigned long now; 3526 3527 now = jiffies; 3528 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3529 !!(rq->cmd_flags & REQ_NOIDLE)); 3530 3531 cfq_update_hw_tag(cfqd); 3532 3533 WARN_ON(!cfqd->rq_in_driver); 3534 WARN_ON(!cfqq->dispatched); 3535 cfqd->rq_in_driver--; 3536 cfqq->dispatched--; 3537 (RQ_CFQG(rq))->dispatched--; 3538 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, 3539 rq_start_time_ns(rq), rq_io_start_time_ns(rq), 3540 rq_data_dir(rq), rq_is_sync(rq)); 3541 3542 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3543 3544 if (sync) { 3545 RQ_CIC(rq)->last_end_request = now; 3546 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3547 cfqd->last_delayed_sync = now; 3548 } 3549 3550 /* 3551 * If this is the active queue, check if it needs to be expired, 3552 * or if we want to idle in case it has no pending requests. 3553 */ 3554 if (cfqd->active_queue == cfqq) { 3555 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3556 3557 if (cfq_cfqq_slice_new(cfqq)) { 3558 cfq_set_prio_slice(cfqd, cfqq); 3559 cfq_clear_cfqq_slice_new(cfqq); 3560 } 3561 3562 /* 3563 * Should we wait for next request to come in before we expire 3564 * the queue. 3565 */ 3566 if (cfq_should_wait_busy(cfqd, cfqq)) { 3567 unsigned long extend_sl = cfqd->cfq_slice_idle; 3568 if (!cfqd->cfq_slice_idle) 3569 extend_sl = cfqd->cfq_group_idle; 3570 cfqq->slice_end = jiffies + extend_sl; 3571 cfq_mark_cfqq_wait_busy(cfqq); 3572 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3573 } 3574 3575 /* 3576 * Idling is not enabled on: 3577 * - expired queues 3578 * - idle-priority queues 3579 * - async queues 3580 * - queues with still some requests queued 3581 * - when there is a close cooperator 3582 */ 3583 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3584 cfq_slice_expired(cfqd, 1); 3585 else if (sync && cfqq_empty && 3586 !cfq_close_cooperator(cfqd, cfqq)) { 3587 cfq_arm_slice_timer(cfqd); 3588 } 3589 } 3590 3591 if (!cfqd->rq_in_driver) 3592 cfq_schedule_dispatch(cfqd); 3593} 3594 3595static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3596{ 3597 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3598 cfq_mark_cfqq_must_alloc_slice(cfqq); 3599 return ELV_MQUEUE_MUST; 3600 } 3601 3602 return ELV_MQUEUE_MAY; 3603} 3604 3605static int cfq_may_queue(struct request_queue *q, int rw) 3606{ 3607 struct cfq_data *cfqd = q->elevator->elevator_data; 3608 struct task_struct *tsk = current; 3609 struct cfq_io_context *cic; 3610 struct cfq_queue *cfqq; 3611 3612 /* 3613 * don't force setup of a queue from here, as a call to may_queue 3614 * does not necessarily imply that a request actually will be queued. 3615 * so just lookup a possibly existing queue, or return 'may queue' 3616 * if that fails 3617 */ 3618 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3619 if (!cic) 3620 return ELV_MQUEUE_MAY; 3621 3622 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3623 if (cfqq) { 3624 cfq_init_prio_data(cfqq, cic->ioc); 3625 3626 return __cfq_may_queue(cfqq); 3627 } 3628 3629 return ELV_MQUEUE_MAY; 3630} 3631 3632/* 3633 * queue lock held here 3634 */ 3635static void cfq_put_request(struct request *rq) 3636{ 3637 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3638 3639 if (cfqq) { 3640 const int rw = rq_data_dir(rq); 3641 3642 BUG_ON(!cfqq->allocated[rw]); 3643 cfqq->allocated[rw]--; 3644 3645 put_io_context(RQ_CIC(rq)->ioc); 3646 3647 rq->elevator_private[0] = NULL; 3648 rq->elevator_private[1] = NULL; 3649 3650 /* Put down rq reference on cfqg */ 3651 cfq_put_cfqg(RQ_CFQG(rq)); 3652 rq->elevator_private[2] = NULL; 3653 3654 cfq_put_queue(cfqq); 3655 } 3656} 3657 3658static struct cfq_queue * 3659cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, 3660 struct cfq_queue *cfqq) 3661{ 3662 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3663 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3664 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3665 cfq_put_queue(cfqq); 3666 return cic_to_cfqq(cic, 1); 3667} 3668 3669/* 3670 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3671 * was the last process referring to said cfqq. 3672 */ 3673static struct cfq_queue * 3674split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) 3675{ 3676 if (cfqq_process_refs(cfqq) == 1) { 3677 cfqq->pid = current->pid; 3678 cfq_clear_cfqq_coop(cfqq); 3679 cfq_clear_cfqq_split_coop(cfqq); 3680 return cfqq; 3681 } 3682 3683 cic_set_cfqq(cic, NULL, 1); 3684 3685 cfq_put_cooperator(cfqq); 3686 3687 cfq_put_queue(cfqq); 3688 return NULL; 3689} 3690/* 3691 * Allocate cfq data structures associated with this request. 3692 */ 3693static int 3694cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3695{ 3696 struct cfq_data *cfqd = q->elevator->elevator_data; 3697 struct cfq_io_context *cic; 3698 const int rw = rq_data_dir(rq); 3699 const bool is_sync = rq_is_sync(rq); 3700 struct cfq_queue *cfqq; 3701 unsigned long flags; 3702 3703 might_sleep_if(gfp_mask & __GFP_WAIT); 3704 3705 cic = cfq_get_io_context(cfqd, gfp_mask); 3706 3707 spin_lock_irqsave(q->queue_lock, flags); 3708 3709 if (!cic) 3710 goto queue_fail; 3711 3712new_queue: 3713 cfqq = cic_to_cfqq(cic, is_sync); 3714 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3715 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); 3716 cic_set_cfqq(cic, cfqq, is_sync); 3717 } else { 3718 /* 3719 * If the queue was seeky for too long, break it apart. 3720 */ 3721 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3722 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3723 cfqq = split_cfqq(cic, cfqq); 3724 if (!cfqq) 3725 goto new_queue; 3726 } 3727 3728 /* 3729 * Check to see if this queue is scheduled to merge with 3730 * another, closely cooperating queue. The merging of 3731 * queues happens here as it must be done in process context. 3732 * The reference on new_cfqq was taken in merge_cfqqs. 3733 */ 3734 if (cfqq->new_cfqq) 3735 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3736 } 3737 3738 cfqq->allocated[rw]++; 3739 3740 cfqq->ref++; 3741 rq->elevator_private[0] = cic; 3742 rq->elevator_private[1] = cfqq; 3743 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); 3744 spin_unlock_irqrestore(q->queue_lock, flags); 3745 return 0; 3746 3747queue_fail: 3748 cfq_schedule_dispatch(cfqd); 3749 spin_unlock_irqrestore(q->queue_lock, flags); 3750 cfq_log(cfqd, "set_request fail"); 3751 return 1; 3752} 3753 3754static void cfq_kick_queue(struct work_struct *work) 3755{ 3756 struct cfq_data *cfqd = 3757 container_of(work, struct cfq_data, unplug_work); 3758 struct request_queue *q = cfqd->queue; 3759 3760 spin_lock_irq(q->queue_lock); 3761 __blk_run_queue(cfqd->queue); 3762 spin_unlock_irq(q->queue_lock); 3763} 3764 3765/* 3766 * Timer running if the active_queue is currently idling inside its time slice 3767 */ 3768static void cfq_idle_slice_timer(unsigned long data) 3769{ 3770 struct cfq_data *cfqd = (struct cfq_data *) data; 3771 struct cfq_queue *cfqq; 3772 unsigned long flags; 3773 int timed_out = 1; 3774 3775 cfq_log(cfqd, "idle timer fired"); 3776 3777 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3778 3779 cfqq = cfqd->active_queue; 3780 if (cfqq) { 3781 timed_out = 0; 3782 3783 /* 3784 * We saw a request before the queue expired, let it through 3785 */ 3786 if (cfq_cfqq_must_dispatch(cfqq)) 3787 goto out_kick; 3788 3789 /* 3790 * expired 3791 */ 3792 if (cfq_slice_used(cfqq)) 3793 goto expire; 3794 3795 /* 3796 * only expire and reinvoke request handler, if there are 3797 * other queues with pending requests 3798 */ 3799 if (!cfqd->busy_queues) 3800 goto out_cont; 3801 3802 /* 3803 * not expired and it has a request pending, let it dispatch 3804 */ 3805 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3806 goto out_kick; 3807 3808 /* 3809 * Queue depth flag is reset only when the idle didn't succeed 3810 */ 3811 cfq_clear_cfqq_deep(cfqq); 3812 } 3813expire: 3814 cfq_slice_expired(cfqd, timed_out); 3815out_kick: 3816 cfq_schedule_dispatch(cfqd); 3817out_cont: 3818 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3819} 3820 3821static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3822{ 3823 del_timer_sync(&cfqd->idle_slice_timer); 3824 cancel_work_sync(&cfqd->unplug_work); 3825} 3826 3827static void cfq_put_async_queues(struct cfq_data *cfqd) 3828{ 3829 int i; 3830 3831 for (i = 0; i < IOPRIO_BE_NR; i++) { 3832 if (cfqd->async_cfqq[0][i]) 3833 cfq_put_queue(cfqd->async_cfqq[0][i]); 3834 if (cfqd->async_cfqq[1][i]) 3835 cfq_put_queue(cfqd->async_cfqq[1][i]); 3836 } 3837 3838 if (cfqd->async_idle_cfqq) 3839 cfq_put_queue(cfqd->async_idle_cfqq); 3840} 3841 3842static void cfq_exit_queue(struct elevator_queue *e) 3843{ 3844 struct cfq_data *cfqd = e->elevator_data; 3845 struct request_queue *q = cfqd->queue; 3846 bool wait = false; 3847 3848 cfq_shutdown_timer_wq(cfqd); 3849 3850 spin_lock_irq(q->queue_lock); 3851 3852 if (cfqd->active_queue) 3853 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3854 3855 while (!list_empty(&cfqd->cic_list)) { 3856 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, 3857 struct cfq_io_context, 3858 queue_list); 3859 3860 __cfq_exit_single_io_context(cfqd, cic); 3861 } 3862 3863 cfq_put_async_queues(cfqd); 3864 cfq_release_cfq_groups(cfqd); 3865 3866 /* 3867 * If there are groups which we could not unlink from blkcg list, 3868 * wait for a rcu period for them to be freed. 3869 */ 3870 if (cfqd->nr_blkcg_linked_grps) 3871 wait = true; 3872 3873 spin_unlock_irq(q->queue_lock); 3874 3875 cfq_shutdown_timer_wq(cfqd); 3876 3877 spin_lock(&cic_index_lock); 3878 ida_remove(&cic_index_ida, cfqd->cic_index); 3879 spin_unlock(&cic_index_lock); 3880 3881 /* 3882 * Wait for cfqg->blkg->key accessors to exit their grace periods. 3883 * Do this wait only if there are other unlinked groups out 3884 * there. This can happen if cgroup deletion path claimed the 3885 * responsibility of cleaning up a group before queue cleanup code 3886 * get to the group. 3887 * 3888 * Do not call synchronize_rcu() unconditionally as there are drivers 3889 * which create/delete request queue hundreds of times during scan/boot 3890 * and synchronize_rcu() can take significant time and slow down boot. 3891 */ 3892 if (wait) 3893 synchronize_rcu(); 3894 3895#ifdef CONFIG_CFQ_GROUP_IOSCHED 3896 /* Free up per cpu stats for root group */ 3897 free_percpu(cfqd->root_group.blkg.stats_cpu); 3898#endif 3899 kfree(cfqd); 3900} 3901 3902static int cfq_alloc_cic_index(void) 3903{ 3904 int index, error; 3905 3906 do { 3907 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) 3908 return -ENOMEM; 3909 3910 spin_lock(&cic_index_lock); 3911 error = ida_get_new(&cic_index_ida, &index); 3912 spin_unlock(&cic_index_lock); 3913 if (error && error != -EAGAIN) 3914 return error; 3915 } while (error); 3916 3917 return index; 3918} 3919 3920static void *cfq_init_queue(struct request_queue *q) 3921{ 3922 struct cfq_data *cfqd; 3923 int i, j; 3924 struct cfq_group *cfqg; 3925 struct cfq_rb_root *st; 3926 3927 i = cfq_alloc_cic_index(); 3928 if (i < 0) 3929 return NULL; 3930 3931 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3932 if (!cfqd) { 3933 spin_lock(&cic_index_lock); 3934 ida_remove(&cic_index_ida, i); 3935 spin_unlock(&cic_index_lock); 3936 return NULL; 3937 } 3938 3939 /* 3940 * Don't need take queue_lock in the routine, since we are 3941 * initializing the ioscheduler, and nobody is using cfqd 3942 */ 3943 cfqd->cic_index = i; 3944 3945 /* Init root service tree */ 3946 cfqd->grp_service_tree = CFQ_RB_ROOT; 3947 3948 /* Init root group */ 3949 cfqg = &cfqd->root_group; 3950 for_each_cfqg_st(cfqg, i, j, st) 3951 *st = CFQ_RB_ROOT; 3952 RB_CLEAR_NODE(&cfqg->rb_node); 3953 3954 /* Give preference to root group over other groups */ 3955 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 3956 3957#ifdef CONFIG_CFQ_GROUP_IOSCHED 3958 /* 3959 * Set root group reference to 2. One reference will be dropped when 3960 * all groups on cfqd->cfqg_list are being deleted during queue exit. 3961 * Other reference will remain there as we don't want to delete this 3962 * group as it is statically allocated and gets destroyed when 3963 * throtl_data goes away. 3964 */ 3965 cfqg->ref = 2; 3966 3967 if (blkio_alloc_blkg_stats(&cfqg->blkg)) { 3968 kfree(cfqg); 3969 kfree(cfqd); 3970 return NULL; 3971 } 3972 3973 rcu_read_lock(); 3974 3975 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, 3976 (void *)cfqd, 0); 3977 rcu_read_unlock(); 3978 cfqd->nr_blkcg_linked_grps++; 3979 3980 /* Add group on cfqd->cfqg_list */ 3981 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 3982#endif 3983 /* 3984 * Not strictly needed (since RB_ROOT just clears the node and we 3985 * zeroed cfqd on alloc), but better be safe in case someone decides 3986 * to add magic to the rb code 3987 */ 3988 for (i = 0; i < CFQ_PRIO_LISTS; i++) 3989 cfqd->prio_trees[i] = RB_ROOT; 3990 3991 /* 3992 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 3993 * Grab a permanent reference to it, so that the normal code flow 3994 * will not attempt to free it. 3995 */ 3996 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 3997 cfqd->oom_cfqq.ref++; 3998 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 3999 4000 INIT_LIST_HEAD(&cfqd->cic_list); 4001 4002 cfqd->queue = q; 4003 4004 init_timer(&cfqd->idle_slice_timer); 4005 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4006 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4007 4008 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4009 4010 cfqd->cfq_quantum = cfq_quantum; 4011 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4012 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4013 cfqd->cfq_back_max = cfq_back_max; 4014 cfqd->cfq_back_penalty = cfq_back_penalty; 4015 cfqd->cfq_slice[0] = cfq_slice_async; 4016 cfqd->cfq_slice[1] = cfq_slice_sync; 4017 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4018 cfqd->cfq_slice_idle = cfq_slice_idle; 4019 cfqd->cfq_group_idle = cfq_group_idle; 4020 cfqd->cfq_latency = 1; 4021 cfqd->hw_tag = -1; 4022 /* 4023 * we optimistically start assuming sync ops weren't delayed in last 4024 * second, in order to have larger depth for async operations. 4025 */ 4026 cfqd->last_delayed_sync = jiffies - HZ; 4027 return cfqd; 4028} 4029 4030static void cfq_slab_kill(void) 4031{ 4032 /* 4033 * Caller already ensured that pending RCU callbacks are completed, 4034 * so we should have no busy allocations at this point. 4035 */ 4036 if (cfq_pool) 4037 kmem_cache_destroy(cfq_pool); 4038 if (cfq_ioc_pool) 4039 kmem_cache_destroy(cfq_ioc_pool); 4040} 4041 4042static int __init cfq_slab_setup(void) 4043{ 4044 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4045 if (!cfq_pool) 4046 goto fail; 4047 4048 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); 4049 if (!cfq_ioc_pool) 4050 goto fail; 4051 4052 return 0; 4053fail: 4054 cfq_slab_kill(); 4055 return -ENOMEM; 4056} 4057 4058/* 4059 * sysfs parts below --> 4060 */ 4061static ssize_t 4062cfq_var_show(unsigned int var, char *page) 4063{ 4064 return sprintf(page, "%d\n", var); 4065} 4066 4067static ssize_t 4068cfq_var_store(unsigned int *var, const char *page, size_t count) 4069{ 4070 char *p = (char *) page; 4071 4072 *var = simple_strtoul(p, &p, 10); 4073 return count; 4074} 4075 4076#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4077static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4078{ \ 4079 struct cfq_data *cfqd = e->elevator_data; \ 4080 unsigned int __data = __VAR; \ 4081 if (__CONV) \ 4082 __data = jiffies_to_msecs(__data); \ 4083 return cfq_var_show(__data, (page)); \ 4084} 4085SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4086SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4087SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4088SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4089SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4090SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4091SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4092SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4093SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4094SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4095SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4096#undef SHOW_FUNCTION 4097 4098#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4099static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4100{ \ 4101 struct cfq_data *cfqd = e->elevator_data; \ 4102 unsigned int __data; \ 4103 int ret = cfq_var_store(&__data, (page), count); \ 4104 if (__data < (MIN)) \ 4105 __data = (MIN); \ 4106 else if (__data > (MAX)) \ 4107 __data = (MAX); \ 4108 if (__CONV) \ 4109 *(__PTR) = msecs_to_jiffies(__data); \ 4110 else \ 4111 *(__PTR) = __data; \ 4112 return ret; \ 4113} 4114STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4115STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4116 UINT_MAX, 1); 4117STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4118 UINT_MAX, 1); 4119STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4120STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4121 UINT_MAX, 0); 4122STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4123STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4124STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4125STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4126STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4127 UINT_MAX, 0); 4128STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4129#undef STORE_FUNCTION 4130 4131#define CFQ_ATTR(name) \ 4132 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4133 4134static struct elv_fs_entry cfq_attrs[] = { 4135 CFQ_ATTR(quantum), 4136 CFQ_ATTR(fifo_expire_sync), 4137 CFQ_ATTR(fifo_expire_async), 4138 CFQ_ATTR(back_seek_max), 4139 CFQ_ATTR(back_seek_penalty), 4140 CFQ_ATTR(slice_sync), 4141 CFQ_ATTR(slice_async), 4142 CFQ_ATTR(slice_async_rq), 4143 CFQ_ATTR(slice_idle), 4144 CFQ_ATTR(group_idle), 4145 CFQ_ATTR(low_latency), 4146 __ATTR_NULL 4147}; 4148 4149static struct elevator_type iosched_cfq = { 4150 .ops = { 4151 .elevator_merge_fn = cfq_merge, 4152 .elevator_merged_fn = cfq_merged_request, 4153 .elevator_merge_req_fn = cfq_merged_requests, 4154 .elevator_allow_merge_fn = cfq_allow_merge, 4155 .elevator_bio_merged_fn = cfq_bio_merged, 4156 .elevator_dispatch_fn = cfq_dispatch_requests, 4157 .elevator_add_req_fn = cfq_insert_request, 4158 .elevator_activate_req_fn = cfq_activate_request, 4159 .elevator_deactivate_req_fn = cfq_deactivate_request, 4160 .elevator_completed_req_fn = cfq_completed_request, 4161 .elevator_former_req_fn = elv_rb_former_request, 4162 .elevator_latter_req_fn = elv_rb_latter_request, 4163 .elevator_set_req_fn = cfq_set_request, 4164 .elevator_put_req_fn = cfq_put_request, 4165 .elevator_may_queue_fn = cfq_may_queue, 4166 .elevator_init_fn = cfq_init_queue, 4167 .elevator_exit_fn = cfq_exit_queue, 4168 .trim = cfq_free_io_context, 4169 }, 4170 .elevator_attrs = cfq_attrs, 4171 .elevator_name = "cfq", 4172 .elevator_owner = THIS_MODULE, 4173}; 4174 4175#ifdef CONFIG_CFQ_GROUP_IOSCHED 4176static struct blkio_policy_type blkio_policy_cfq = { 4177 .ops = { 4178 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 4179 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 4180 }, 4181 .plid = BLKIO_POLICY_PROP, 4182}; 4183#else 4184static struct blkio_policy_type blkio_policy_cfq; 4185#endif 4186 4187static int __init cfq_init(void) 4188{ 4189 /* 4190 * could be 0 on HZ < 1000 setups 4191 */ 4192 if (!cfq_slice_async) 4193 cfq_slice_async = 1; 4194 if (!cfq_slice_idle) 4195 cfq_slice_idle = 1; 4196 4197#ifdef CONFIG_CFQ_GROUP_IOSCHED 4198 if (!cfq_group_idle) 4199 cfq_group_idle = 1; 4200#else 4201 cfq_group_idle = 0; 4202#endif 4203 if (cfq_slab_setup()) 4204 return -ENOMEM; 4205 4206 elv_register(&iosched_cfq); 4207 blkio_policy_register(&blkio_policy_cfq); 4208 4209 return 0; 4210} 4211 4212static void __exit cfq_exit(void) 4213{ 4214 DECLARE_COMPLETION_ONSTACK(all_gone); 4215 blkio_policy_unregister(&blkio_policy_cfq); 4216 elv_unregister(&iosched_cfq); 4217 ioc_gone = &all_gone; 4218 /* ioc_gone's update must be visible before reading ioc_count */ 4219 smp_wmb(); 4220 4221 /* 4222 * this also protects us from entering cfq_slab_kill() with 4223 * pending RCU callbacks 4224 */ 4225 if (elv_ioc_count_read(cfq_ioc_count)) 4226 wait_for_completion(&all_gone); 4227 ida_destroy(&cic_index_ida); 4228 cfq_slab_kill(); 4229} 4230 4231module_init(cfq_init); 4232module_exit(cfq_exit); 4233 4234MODULE_AUTHOR("Jens Axboe"); 4235MODULE_LICENSE("GPL"); 4236MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4237