cfq-iosched.c revision 3c96cb32d318f323c1bf972a4c66821f8499e34d
1/* 2 * CFQ, or complete fairness queueing, disk scheduler. 3 * 4 * Based on ideas from a previously unfinished io 5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. 6 * 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> 8 */ 9#include <linux/module.h> 10#include <linux/slab.h> 11#include <linux/blkdev.h> 12#include <linux/elevator.h> 13#include <linux/jiffies.h> 14#include <linux/rbtree.h> 15#include <linux/ioprio.h> 16#include <linux/blktrace_api.h> 17#include "blk.h" 18#include "blk-cgroup.h" 19 20static struct blkio_policy_type blkio_policy_cfq __maybe_unused; 21 22/* 23 * tunables 24 */ 25/* max queue in one round of service */ 26static const int cfq_quantum = 8; 27static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 28/* maximum backwards seek, in KiB */ 29static const int cfq_back_max = 16 * 1024; 30/* penalty of a backwards seek */ 31static const int cfq_back_penalty = 2; 32static const int cfq_slice_sync = HZ / 10; 33static int cfq_slice_async = HZ / 25; 34static const int cfq_slice_async_rq = 2; 35static int cfq_slice_idle = HZ / 125; 36static int cfq_group_idle = HZ / 125; 37static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 38static const int cfq_hist_divisor = 4; 39 40/* 41 * offset from end of service tree 42 */ 43#define CFQ_IDLE_DELAY (HZ / 5) 44 45/* 46 * below this threshold, we consider thinktime immediate 47 */ 48#define CFQ_MIN_TT (2) 49 50#define CFQ_SLICE_SCALE (5) 51#define CFQ_HW_QUEUE_MIN (5) 52#define CFQ_SERVICE_SHIFT 12 53 54#define CFQQ_SEEK_THR (sector_t)(8 * 100) 55#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 56#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 57#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 58 59#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq) 60#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0]) 61#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1]) 62 63static struct kmem_cache *cfq_pool; 64 65#define CFQ_PRIO_LISTS IOPRIO_BE_NR 66#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 67#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 68 69#define sample_valid(samples) ((samples) > 80) 70#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 71 72struct cfq_ttime { 73 unsigned long last_end_request; 74 75 unsigned long ttime_total; 76 unsigned long ttime_samples; 77 unsigned long ttime_mean; 78}; 79 80/* 81 * Most of our rbtree usage is for sorting with min extraction, so 82 * if we cache the leftmost node we don't have to walk down the tree 83 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 84 * move this into the elevator for the rq sorting as well. 85 */ 86struct cfq_rb_root { 87 struct rb_root rb; 88 struct rb_node *left; 89 unsigned count; 90 unsigned total_weight; 91 u64 min_vdisktime; 92 struct cfq_ttime ttime; 93}; 94#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \ 95 .ttime = {.last_end_request = jiffies,},} 96 97/* 98 * Per process-grouping structure 99 */ 100struct cfq_queue { 101 /* reference count */ 102 int ref; 103 /* various state flags, see below */ 104 unsigned int flags; 105 /* parent cfq_data */ 106 struct cfq_data *cfqd; 107 /* service_tree member */ 108 struct rb_node rb_node; 109 /* service_tree key */ 110 unsigned long rb_key; 111 /* prio tree member */ 112 struct rb_node p_node; 113 /* prio tree root we belong to, if any */ 114 struct rb_root *p_root; 115 /* sorted list of pending requests */ 116 struct rb_root sort_list; 117 /* if fifo isn't expired, next request to serve */ 118 struct request *next_rq; 119 /* requests queued in sort_list */ 120 int queued[2]; 121 /* currently allocated requests */ 122 int allocated[2]; 123 /* fifo list of requests in sort_list */ 124 struct list_head fifo; 125 126 /* time when queue got scheduled in to dispatch first request. */ 127 unsigned long dispatch_start; 128 unsigned int allocated_slice; 129 unsigned int slice_dispatch; 130 /* time when first request from queue completed and slice started. */ 131 unsigned long slice_start; 132 unsigned long slice_end; 133 long slice_resid; 134 135 /* pending priority requests */ 136 int prio_pending; 137 /* number of requests that are on the dispatch list or inside driver */ 138 int dispatched; 139 140 /* io prio of this group */ 141 unsigned short ioprio, org_ioprio; 142 unsigned short ioprio_class; 143 144 pid_t pid; 145 146 u32 seek_history; 147 sector_t last_request_pos; 148 149 struct cfq_rb_root *service_tree; 150 struct cfq_queue *new_cfqq; 151 struct cfq_group *cfqg; 152 /* Number of sectors dispatched from queue in single dispatch round */ 153 unsigned long nr_sectors; 154}; 155 156/* 157 * First index in the service_trees. 158 * IDLE is handled separately, so it has negative index 159 */ 160enum wl_prio_t { 161 BE_WORKLOAD = 0, 162 RT_WORKLOAD = 1, 163 IDLE_WORKLOAD = 2, 164 CFQ_PRIO_NR, 165}; 166 167/* 168 * Second index in the service_trees. 169 */ 170enum wl_type_t { 171 ASYNC_WORKLOAD = 0, 172 SYNC_NOIDLE_WORKLOAD = 1, 173 SYNC_WORKLOAD = 2 174}; 175 176struct cfqg_stats { 177#ifdef CONFIG_CFQ_GROUP_IOSCHED 178 /* total bytes transferred */ 179 struct blkg_rwstat service_bytes; 180 /* total IOs serviced, post merge */ 181 struct blkg_rwstat serviced; 182 /* number of ios merged */ 183 struct blkg_rwstat merged; 184 /* total time spent on device in ns, may not be accurate w/ queueing */ 185 struct blkg_rwstat service_time; 186 /* total time spent waiting in scheduler queue in ns */ 187 struct blkg_rwstat wait_time; 188 /* number of IOs queued up */ 189 struct blkg_rwstat queued; 190 /* total sectors transferred */ 191 struct blkg_stat sectors; 192 /* total disk time and nr sectors dispatched by this group */ 193 struct blkg_stat time; 194#ifdef CONFIG_DEBUG_BLK_CGROUP 195 /* time not charged to this cgroup */ 196 struct blkg_stat unaccounted_time; 197 /* sum of number of ios queued across all samples */ 198 struct blkg_stat avg_queue_size_sum; 199 /* count of samples taken for average */ 200 struct blkg_stat avg_queue_size_samples; 201 /* how many times this group has been removed from service tree */ 202 struct blkg_stat dequeue; 203 /* total time spent waiting for it to be assigned a timeslice. */ 204 struct blkg_stat group_wait_time; 205 /* time spent idling for this blkio_group */ 206 struct blkg_stat idle_time; 207 /* total time with empty current active q with other requests queued */ 208 struct blkg_stat empty_time; 209 /* fields after this shouldn't be cleared on stat reset */ 210 uint64_t start_group_wait_time; 211 uint64_t start_idle_time; 212 uint64_t start_empty_time; 213 uint16_t flags; 214#endif /* CONFIG_DEBUG_BLK_CGROUP */ 215#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 216}; 217 218/* This is per cgroup per device grouping structure */ 219struct cfq_group { 220 /* group service_tree member */ 221 struct rb_node rb_node; 222 223 /* group service_tree key */ 224 u64 vdisktime; 225 unsigned int weight; 226 unsigned int new_weight; 227 unsigned int dev_weight; 228 229 /* number of cfqq currently on this group */ 230 int nr_cfqq; 231 232 /* 233 * Per group busy queues average. Useful for workload slice calc. We 234 * create the array for each prio class but at run time it is used 235 * only for RT and BE class and slot for IDLE class remains unused. 236 * This is primarily done to avoid confusion and a gcc warning. 237 */ 238 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 239 /* 240 * rr lists of queues with requests. We maintain service trees for 241 * RT and BE classes. These trees are subdivided in subclasses 242 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 243 * class there is no subclassification and all the cfq queues go on 244 * a single tree service_tree_idle. 245 * Counts are embedded in the cfq_rb_root 246 */ 247 struct cfq_rb_root service_trees[2][3]; 248 struct cfq_rb_root service_tree_idle; 249 250 unsigned long saved_workload_slice; 251 enum wl_type_t saved_workload; 252 enum wl_prio_t saved_serving_prio; 253 254 /* number of requests that are on the dispatch list or inside driver */ 255 int dispatched; 256 struct cfq_ttime ttime; 257 struct cfqg_stats stats; 258}; 259 260struct cfq_io_cq { 261 struct io_cq icq; /* must be the first member */ 262 struct cfq_queue *cfqq[2]; 263 struct cfq_ttime ttime; 264 int ioprio; /* the current ioprio */ 265#ifdef CONFIG_CFQ_GROUP_IOSCHED 266 uint64_t blkcg_id; /* the current blkcg ID */ 267#endif 268}; 269 270/* 271 * Per block device queue structure 272 */ 273struct cfq_data { 274 struct request_queue *queue; 275 /* Root service tree for cfq_groups */ 276 struct cfq_rb_root grp_service_tree; 277 struct cfq_group *root_group; 278 279 /* 280 * The priority currently being served 281 */ 282 enum wl_prio_t serving_prio; 283 enum wl_type_t serving_type; 284 unsigned long workload_expires; 285 struct cfq_group *serving_group; 286 287 /* 288 * Each priority tree is sorted by next_request position. These 289 * trees are used when determining if two or more queues are 290 * interleaving requests (see cfq_close_cooperator). 291 */ 292 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 293 294 unsigned int busy_queues; 295 unsigned int busy_sync_queues; 296 297 int rq_in_driver; 298 int rq_in_flight[2]; 299 300 /* 301 * queue-depth detection 302 */ 303 int rq_queued; 304 int hw_tag; 305 /* 306 * hw_tag can be 307 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 308 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 309 * 0 => no NCQ 310 */ 311 int hw_tag_est_depth; 312 unsigned int hw_tag_samples; 313 314 /* 315 * idle window management 316 */ 317 struct timer_list idle_slice_timer; 318 struct work_struct unplug_work; 319 320 struct cfq_queue *active_queue; 321 struct cfq_io_cq *active_cic; 322 323 /* 324 * async queue for each priority case 325 */ 326 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 327 struct cfq_queue *async_idle_cfqq; 328 329 sector_t last_position; 330 331 /* 332 * tunables, see top of file 333 */ 334 unsigned int cfq_quantum; 335 unsigned int cfq_fifo_expire[2]; 336 unsigned int cfq_back_penalty; 337 unsigned int cfq_back_max; 338 unsigned int cfq_slice[2]; 339 unsigned int cfq_slice_async_rq; 340 unsigned int cfq_slice_idle; 341 unsigned int cfq_group_idle; 342 unsigned int cfq_latency; 343 344 /* 345 * Fallback dummy cfqq for extreme OOM conditions 346 */ 347 struct cfq_queue oom_cfqq; 348 349 unsigned long last_delayed_sync; 350}; 351 352static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 353 354static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 355 enum wl_prio_t prio, 356 enum wl_type_t type) 357{ 358 if (!cfqg) 359 return NULL; 360 361 if (prio == IDLE_WORKLOAD) 362 return &cfqg->service_tree_idle; 363 364 return &cfqg->service_trees[prio][type]; 365} 366 367enum cfqq_state_flags { 368 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 369 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 370 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 371 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 372 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 373 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 374 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 375 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 376 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 377 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 378 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 379 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 380 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 381}; 382 383#define CFQ_CFQQ_FNS(name) \ 384static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 385{ \ 386 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 387} \ 388static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 389{ \ 390 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 391} \ 392static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 393{ \ 394 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 395} 396 397CFQ_CFQQ_FNS(on_rr); 398CFQ_CFQQ_FNS(wait_request); 399CFQ_CFQQ_FNS(must_dispatch); 400CFQ_CFQQ_FNS(must_alloc_slice); 401CFQ_CFQQ_FNS(fifo_expire); 402CFQ_CFQQ_FNS(idle_window); 403CFQ_CFQQ_FNS(prio_changed); 404CFQ_CFQQ_FNS(slice_new); 405CFQ_CFQQ_FNS(sync); 406CFQ_CFQQ_FNS(coop); 407CFQ_CFQQ_FNS(split_coop); 408CFQ_CFQQ_FNS(deep); 409CFQ_CFQQ_FNS(wait_busy); 410#undef CFQ_CFQQ_FNS 411 412#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP) 413 414/* cfqg stats flags */ 415enum cfqg_stats_flags { 416 CFQG_stats_waiting = 0, 417 CFQG_stats_idling, 418 CFQG_stats_empty, 419}; 420 421#define CFQG_FLAG_FNS(name) \ 422static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \ 423{ \ 424 stats->flags |= (1 << CFQG_stats_##name); \ 425} \ 426static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \ 427{ \ 428 stats->flags &= ~(1 << CFQG_stats_##name); \ 429} \ 430static inline int cfqg_stats_##name(struct cfqg_stats *stats) \ 431{ \ 432 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \ 433} \ 434 435CFQG_FLAG_FNS(waiting) 436CFQG_FLAG_FNS(idling) 437CFQG_FLAG_FNS(empty) 438#undef CFQG_FLAG_FNS 439 440/* This should be called with the queue_lock held. */ 441static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats) 442{ 443 unsigned long long now; 444 445 if (!cfqg_stats_waiting(stats)) 446 return; 447 448 now = sched_clock(); 449 if (time_after64(now, stats->start_group_wait_time)) 450 blkg_stat_add(&stats->group_wait_time, 451 now - stats->start_group_wait_time); 452 cfqg_stats_clear_waiting(stats); 453} 454 455/* This should be called with the queue_lock held. */ 456static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, 457 struct cfq_group *curr_cfqg) 458{ 459 struct cfqg_stats *stats = &cfqg->stats; 460 461 if (cfqg_stats_waiting(stats)) 462 return; 463 if (cfqg == curr_cfqg) 464 return; 465 stats->start_group_wait_time = sched_clock(); 466 cfqg_stats_mark_waiting(stats); 467} 468 469/* This should be called with the queue_lock held. */ 470static void cfqg_stats_end_empty_time(struct cfqg_stats *stats) 471{ 472 unsigned long long now; 473 474 if (!cfqg_stats_empty(stats)) 475 return; 476 477 now = sched_clock(); 478 if (time_after64(now, stats->start_empty_time)) 479 blkg_stat_add(&stats->empty_time, 480 now - stats->start_empty_time); 481 cfqg_stats_clear_empty(stats); 482} 483 484static void cfqg_stats_update_dequeue(struct cfq_group *cfqg) 485{ 486 blkg_stat_add(&cfqg->stats.dequeue, 1); 487} 488 489static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) 490{ 491 struct cfqg_stats *stats = &cfqg->stats; 492 493 if (blkg_rwstat_sum(&stats->queued)) 494 return; 495 496 /* 497 * group is already marked empty. This can happen if cfqq got new 498 * request in parent group and moved to this group while being added 499 * to service tree. Just ignore the event and move on. 500 */ 501 if (cfqg_stats_empty(stats)) 502 return; 503 504 stats->start_empty_time = sched_clock(); 505 cfqg_stats_mark_empty(stats); 506} 507 508static void cfqg_stats_update_idle_time(struct cfq_group *cfqg) 509{ 510 struct cfqg_stats *stats = &cfqg->stats; 511 512 if (cfqg_stats_idling(stats)) { 513 unsigned long long now = sched_clock(); 514 515 if (time_after64(now, stats->start_idle_time)) 516 blkg_stat_add(&stats->idle_time, 517 now - stats->start_idle_time); 518 cfqg_stats_clear_idling(stats); 519 } 520} 521 522static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) 523{ 524 struct cfqg_stats *stats = &cfqg->stats; 525 526 BUG_ON(cfqg_stats_idling(stats)); 527 528 stats->start_idle_time = sched_clock(); 529 cfqg_stats_mark_idling(stats); 530} 531 532static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) 533{ 534 struct cfqg_stats *stats = &cfqg->stats; 535 536 blkg_stat_add(&stats->avg_queue_size_sum, 537 blkg_rwstat_sum(&stats->queued)); 538 blkg_stat_add(&stats->avg_queue_size_samples, 1); 539 cfqg_stats_update_group_wait_time(stats); 540} 541 542#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 543 544static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { } 545static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { } 546static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { } 547static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { } 548static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { } 549static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { } 550static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { } 551 552#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 553 554#ifdef CONFIG_CFQ_GROUP_IOSCHED 555 556static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg) 557{ 558 return blkg_to_pdata(blkg, &blkio_policy_cfq); 559} 560 561static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg) 562{ 563 return pdata_to_blkg(cfqg); 564} 565 566static inline void cfqg_get(struct cfq_group *cfqg) 567{ 568 return blkg_get(cfqg_to_blkg(cfqg)); 569} 570 571static inline void cfqg_put(struct cfq_group *cfqg) 572{ 573 return blkg_put(cfqg_to_blkg(cfqg)); 574} 575 576#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 577 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 578 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 579 blkg_path(cfqg_to_blkg((cfqq)->cfqg)), ##args) 580 581#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 582 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 583 blkg_path(cfqg_to_blkg((cfqg))), ##args) \ 584 585static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 586 struct cfq_group *curr_cfqg, int rw) 587{ 588 blkg_rwstat_add(&cfqg->stats.queued, rw, 1); 589 cfqg_stats_end_empty_time(&cfqg->stats); 590 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg); 591} 592 593static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 594 unsigned long time, unsigned long unaccounted_time) 595{ 596 blkg_stat_add(&cfqg->stats.time, time); 597#ifdef CONFIG_DEBUG_BLK_CGROUP 598 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time); 599#endif 600} 601 602static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) 603{ 604 blkg_rwstat_add(&cfqg->stats.queued, rw, -1); 605} 606 607static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) 608{ 609 blkg_rwstat_add(&cfqg->stats.merged, rw, 1); 610} 611 612static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 613 uint64_t bytes, int rw) 614{ 615 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9); 616 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1); 617 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes); 618} 619 620static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 621 uint64_t start_time, uint64_t io_start_time, int rw) 622{ 623 struct cfqg_stats *stats = &cfqg->stats; 624 unsigned long long now = sched_clock(); 625 626 if (time_after64(now, io_start_time)) 627 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time); 628 if (time_after64(io_start_time, start_time)) 629 blkg_rwstat_add(&stats->wait_time, rw, 630 io_start_time - start_time); 631} 632 633static void cfqg_stats_reset(struct blkio_group *blkg) 634{ 635 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 636 struct cfqg_stats *stats = &cfqg->stats; 637 638 /* queued stats shouldn't be cleared */ 639 blkg_rwstat_reset(&stats->service_bytes); 640 blkg_rwstat_reset(&stats->serviced); 641 blkg_rwstat_reset(&stats->merged); 642 blkg_rwstat_reset(&stats->service_time); 643 blkg_rwstat_reset(&stats->wait_time); 644 blkg_stat_reset(&stats->time); 645#ifdef CONFIG_DEBUG_BLK_CGROUP 646 blkg_stat_reset(&stats->unaccounted_time); 647 blkg_stat_reset(&stats->avg_queue_size_sum); 648 blkg_stat_reset(&stats->avg_queue_size_samples); 649 blkg_stat_reset(&stats->dequeue); 650 blkg_stat_reset(&stats->group_wait_time); 651 blkg_stat_reset(&stats->idle_time); 652 blkg_stat_reset(&stats->empty_time); 653#endif 654} 655 656#else /* CONFIG_CFQ_GROUP_IOSCHED */ 657 658static inline struct cfq_group *blkg_to_cfqg(struct blkio_group *blkg) { return NULL; } 659static inline struct blkio_group *cfqg_to_blkg(struct cfq_group *cfqg) { return NULL; } 660static inline void cfqg_get(struct cfq_group *cfqg) { } 661static inline void cfqg_put(struct cfq_group *cfqg) { } 662 663#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 664 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 665#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 666 667static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 668 struct cfq_group *curr_cfqg, int rw) { } 669static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 670 unsigned long time, unsigned long unaccounted_time) { } 671static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { } 672static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { } 673static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 674 uint64_t bytes, int rw) { } 675static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 676 uint64_t start_time, uint64_t io_start_time, int rw) { } 677 678#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 679 680#define cfq_log(cfqd, fmt, args...) \ 681 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 682 683/* Traverses through cfq group service trees */ 684#define for_each_cfqg_st(cfqg, i, j, st) \ 685 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 686 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 687 : &cfqg->service_tree_idle; \ 688 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 689 (i == IDLE_WORKLOAD && j == 0); \ 690 j++, st = i < IDLE_WORKLOAD ? \ 691 &cfqg->service_trees[i][j]: NULL) \ 692 693static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, 694 struct cfq_ttime *ttime, bool group_idle) 695{ 696 unsigned long slice; 697 if (!sample_valid(ttime->ttime_samples)) 698 return false; 699 if (group_idle) 700 slice = cfqd->cfq_group_idle; 701 else 702 slice = cfqd->cfq_slice_idle; 703 return ttime->ttime_mean > slice; 704} 705 706static inline bool iops_mode(struct cfq_data *cfqd) 707{ 708 /* 709 * If we are not idling on queues and it is a NCQ drive, parallel 710 * execution of requests is on and measuring time is not possible 711 * in most of the cases until and unless we drive shallower queue 712 * depths and that becomes a performance bottleneck. In such cases 713 * switch to start providing fairness in terms of number of IOs. 714 */ 715 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 716 return true; 717 else 718 return false; 719} 720 721static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 722{ 723 if (cfq_class_idle(cfqq)) 724 return IDLE_WORKLOAD; 725 if (cfq_class_rt(cfqq)) 726 return RT_WORKLOAD; 727 return BE_WORKLOAD; 728} 729 730 731static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 732{ 733 if (!cfq_cfqq_sync(cfqq)) 734 return ASYNC_WORKLOAD; 735 if (!cfq_cfqq_idle_window(cfqq)) 736 return SYNC_NOIDLE_WORKLOAD; 737 return SYNC_WORKLOAD; 738} 739 740static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 741 struct cfq_data *cfqd, 742 struct cfq_group *cfqg) 743{ 744 if (wl == IDLE_WORKLOAD) 745 return cfqg->service_tree_idle.count; 746 747 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 748 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 749 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 750} 751 752static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 753 struct cfq_group *cfqg) 754{ 755 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 756 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 757} 758 759static void cfq_dispatch_insert(struct request_queue *, struct request *); 760static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync, 761 struct cfq_io_cq *cic, struct bio *bio, 762 gfp_t gfp_mask); 763 764static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq) 765{ 766 /* cic->icq is the first member, %NULL will convert to %NULL */ 767 return container_of(icq, struct cfq_io_cq, icq); 768} 769 770static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd, 771 struct io_context *ioc) 772{ 773 if (ioc) 774 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue)); 775 return NULL; 776} 777 778static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync) 779{ 780 return cic->cfqq[is_sync]; 781} 782 783static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq, 784 bool is_sync) 785{ 786 cic->cfqq[is_sync] = cfqq; 787} 788 789static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic) 790{ 791 return cic->icq.q->elevator->elevator_data; 792} 793 794/* 795 * We regard a request as SYNC, if it's either a read or has the SYNC bit 796 * set (in which case it could also be direct WRITE). 797 */ 798static inline bool cfq_bio_sync(struct bio *bio) 799{ 800 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 801} 802 803/* 804 * scheduler run of queue, if there are requests pending and no one in the 805 * driver that will restart queueing 806 */ 807static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 808{ 809 if (cfqd->busy_queues) { 810 cfq_log(cfqd, "schedule dispatch"); 811 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 812 } 813} 814 815/* 816 * Scale schedule slice based on io priority. Use the sync time slice only 817 * if a queue is marked sync and has sync io queued. A sync queue with async 818 * io only, should not get full sync slice length. 819 */ 820static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 821 unsigned short prio) 822{ 823 const int base_slice = cfqd->cfq_slice[sync]; 824 825 WARN_ON(prio >= IOPRIO_BE_NR); 826 827 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 828} 829 830static inline int 831cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 832{ 833 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 834} 835 836static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 837{ 838 u64 d = delta << CFQ_SERVICE_SHIFT; 839 840 d = d * CFQ_WEIGHT_DEFAULT; 841 do_div(d, cfqg->weight); 842 return d; 843} 844 845static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 846{ 847 s64 delta = (s64)(vdisktime - min_vdisktime); 848 if (delta > 0) 849 min_vdisktime = vdisktime; 850 851 return min_vdisktime; 852} 853 854static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 855{ 856 s64 delta = (s64)(vdisktime - min_vdisktime); 857 if (delta < 0) 858 min_vdisktime = vdisktime; 859 860 return min_vdisktime; 861} 862 863static void update_min_vdisktime(struct cfq_rb_root *st) 864{ 865 struct cfq_group *cfqg; 866 867 if (st->left) { 868 cfqg = rb_entry_cfqg(st->left); 869 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 870 cfqg->vdisktime); 871 } 872} 873 874/* 875 * get averaged number of queues of RT/BE priority. 876 * average is updated, with a formula that gives more weight to higher numbers, 877 * to quickly follows sudden increases and decrease slowly 878 */ 879 880static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 881 struct cfq_group *cfqg, bool rt) 882{ 883 unsigned min_q, max_q; 884 unsigned mult = cfq_hist_divisor - 1; 885 unsigned round = cfq_hist_divisor / 2; 886 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 887 888 min_q = min(cfqg->busy_queues_avg[rt], busy); 889 max_q = max(cfqg->busy_queues_avg[rt], busy); 890 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 891 cfq_hist_divisor; 892 return cfqg->busy_queues_avg[rt]; 893} 894 895static inline unsigned 896cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 897{ 898 struct cfq_rb_root *st = &cfqd->grp_service_tree; 899 900 return cfq_target_latency * cfqg->weight / st->total_weight; 901} 902 903static inline unsigned 904cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 905{ 906 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 907 if (cfqd->cfq_latency) { 908 /* 909 * interested queues (we consider only the ones with the same 910 * priority class in the cfq group) 911 */ 912 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 913 cfq_class_rt(cfqq)); 914 unsigned sync_slice = cfqd->cfq_slice[1]; 915 unsigned expect_latency = sync_slice * iq; 916 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 917 918 if (expect_latency > group_slice) { 919 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 920 /* scale low_slice according to IO priority 921 * and sync vs async */ 922 unsigned low_slice = 923 min(slice, base_low_slice * slice / sync_slice); 924 /* the adapted slice value is scaled to fit all iqs 925 * into the target latency */ 926 slice = max(slice * group_slice / expect_latency, 927 low_slice); 928 } 929 } 930 return slice; 931} 932 933static inline void 934cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 935{ 936 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 937 938 cfqq->slice_start = jiffies; 939 cfqq->slice_end = jiffies + slice; 940 cfqq->allocated_slice = slice; 941 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 942} 943 944/* 945 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 946 * isn't valid until the first request from the dispatch is activated 947 * and the slice time set. 948 */ 949static inline bool cfq_slice_used(struct cfq_queue *cfqq) 950{ 951 if (cfq_cfqq_slice_new(cfqq)) 952 return false; 953 if (time_before(jiffies, cfqq->slice_end)) 954 return false; 955 956 return true; 957} 958 959/* 960 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 961 * We choose the request that is closest to the head right now. Distance 962 * behind the head is penalized and only allowed to a certain extent. 963 */ 964static struct request * 965cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 966{ 967 sector_t s1, s2, d1 = 0, d2 = 0; 968 unsigned long back_max; 969#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 970#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 971 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 972 973 if (rq1 == NULL || rq1 == rq2) 974 return rq2; 975 if (rq2 == NULL) 976 return rq1; 977 978 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 979 return rq_is_sync(rq1) ? rq1 : rq2; 980 981 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) 982 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; 983 984 s1 = blk_rq_pos(rq1); 985 s2 = blk_rq_pos(rq2); 986 987 /* 988 * by definition, 1KiB is 2 sectors 989 */ 990 back_max = cfqd->cfq_back_max * 2; 991 992 /* 993 * Strict one way elevator _except_ in the case where we allow 994 * short backward seeks which are biased as twice the cost of a 995 * similar forward seek. 996 */ 997 if (s1 >= last) 998 d1 = s1 - last; 999 else if (s1 + back_max >= last) 1000 d1 = (last - s1) * cfqd->cfq_back_penalty; 1001 else 1002 wrap |= CFQ_RQ1_WRAP; 1003 1004 if (s2 >= last) 1005 d2 = s2 - last; 1006 else if (s2 + back_max >= last) 1007 d2 = (last - s2) * cfqd->cfq_back_penalty; 1008 else 1009 wrap |= CFQ_RQ2_WRAP; 1010 1011 /* Found required data */ 1012 1013 /* 1014 * By doing switch() on the bit mask "wrap" we avoid having to 1015 * check two variables for all permutations: --> faster! 1016 */ 1017 switch (wrap) { 1018 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 1019 if (d1 < d2) 1020 return rq1; 1021 else if (d2 < d1) 1022 return rq2; 1023 else { 1024 if (s1 >= s2) 1025 return rq1; 1026 else 1027 return rq2; 1028 } 1029 1030 case CFQ_RQ2_WRAP: 1031 return rq1; 1032 case CFQ_RQ1_WRAP: 1033 return rq2; 1034 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 1035 default: 1036 /* 1037 * Since both rqs are wrapped, 1038 * start with the one that's further behind head 1039 * (--> only *one* back seek required), 1040 * since back seek takes more time than forward. 1041 */ 1042 if (s1 <= s2) 1043 return rq1; 1044 else 1045 return rq2; 1046 } 1047} 1048 1049/* 1050 * The below is leftmost cache rbtree addon 1051 */ 1052static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 1053{ 1054 /* Service tree is empty */ 1055 if (!root->count) 1056 return NULL; 1057 1058 if (!root->left) 1059 root->left = rb_first(&root->rb); 1060 1061 if (root->left) 1062 return rb_entry(root->left, struct cfq_queue, rb_node); 1063 1064 return NULL; 1065} 1066 1067static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 1068{ 1069 if (!root->left) 1070 root->left = rb_first(&root->rb); 1071 1072 if (root->left) 1073 return rb_entry_cfqg(root->left); 1074 1075 return NULL; 1076} 1077 1078static void rb_erase_init(struct rb_node *n, struct rb_root *root) 1079{ 1080 rb_erase(n, root); 1081 RB_CLEAR_NODE(n); 1082} 1083 1084static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 1085{ 1086 if (root->left == n) 1087 root->left = NULL; 1088 rb_erase_init(n, &root->rb); 1089 --root->count; 1090} 1091 1092/* 1093 * would be nice to take fifo expire time into account as well 1094 */ 1095static struct request * 1096cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1097 struct request *last) 1098{ 1099 struct rb_node *rbnext = rb_next(&last->rb_node); 1100 struct rb_node *rbprev = rb_prev(&last->rb_node); 1101 struct request *next = NULL, *prev = NULL; 1102 1103 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 1104 1105 if (rbprev) 1106 prev = rb_entry_rq(rbprev); 1107 1108 if (rbnext) 1109 next = rb_entry_rq(rbnext); 1110 else { 1111 rbnext = rb_first(&cfqq->sort_list); 1112 if (rbnext && rbnext != &last->rb_node) 1113 next = rb_entry_rq(rbnext); 1114 } 1115 1116 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 1117} 1118 1119static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 1120 struct cfq_queue *cfqq) 1121{ 1122 /* 1123 * just an approximation, should be ok. 1124 */ 1125 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 1126 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 1127} 1128 1129static inline s64 1130cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 1131{ 1132 return cfqg->vdisktime - st->min_vdisktime; 1133} 1134 1135static void 1136__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1137{ 1138 struct rb_node **node = &st->rb.rb_node; 1139 struct rb_node *parent = NULL; 1140 struct cfq_group *__cfqg; 1141 s64 key = cfqg_key(st, cfqg); 1142 int left = 1; 1143 1144 while (*node != NULL) { 1145 parent = *node; 1146 __cfqg = rb_entry_cfqg(parent); 1147 1148 if (key < cfqg_key(st, __cfqg)) 1149 node = &parent->rb_left; 1150 else { 1151 node = &parent->rb_right; 1152 left = 0; 1153 } 1154 } 1155 1156 if (left) 1157 st->left = &cfqg->rb_node; 1158 1159 rb_link_node(&cfqg->rb_node, parent, node); 1160 rb_insert_color(&cfqg->rb_node, &st->rb); 1161} 1162 1163static void 1164cfq_update_group_weight(struct cfq_group *cfqg) 1165{ 1166 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1167 if (cfqg->new_weight) { 1168 cfqg->weight = cfqg->new_weight; 1169 cfqg->new_weight = 0; 1170 } 1171} 1172 1173static void 1174cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1175{ 1176 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1177 1178 cfq_update_group_weight(cfqg); 1179 __cfq_group_service_tree_add(st, cfqg); 1180 st->total_weight += cfqg->weight; 1181} 1182 1183static void 1184cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 1185{ 1186 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1187 struct cfq_group *__cfqg; 1188 struct rb_node *n; 1189 1190 cfqg->nr_cfqq++; 1191 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1192 return; 1193 1194 /* 1195 * Currently put the group at the end. Later implement something 1196 * so that groups get lesser vtime based on their weights, so that 1197 * if group does not loose all if it was not continuously backlogged. 1198 */ 1199 n = rb_last(&st->rb); 1200 if (n) { 1201 __cfqg = rb_entry_cfqg(n); 1202 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 1203 } else 1204 cfqg->vdisktime = st->min_vdisktime; 1205 cfq_group_service_tree_add(st, cfqg); 1206} 1207 1208static void 1209cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 1210{ 1211 st->total_weight -= cfqg->weight; 1212 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1213 cfq_rb_erase(&cfqg->rb_node, st); 1214} 1215 1216static void 1217cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 1218{ 1219 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1220 1221 BUG_ON(cfqg->nr_cfqq < 1); 1222 cfqg->nr_cfqq--; 1223 1224 /* If there are other cfq queues under this group, don't delete it */ 1225 if (cfqg->nr_cfqq) 1226 return; 1227 1228 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 1229 cfq_group_service_tree_del(st, cfqg); 1230 cfqg->saved_workload_slice = 0; 1231 cfqg_stats_update_dequeue(cfqg); 1232} 1233 1234static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 1235 unsigned int *unaccounted_time) 1236{ 1237 unsigned int slice_used; 1238 1239 /* 1240 * Queue got expired before even a single request completed or 1241 * got expired immediately after first request completion. 1242 */ 1243 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 1244 /* 1245 * Also charge the seek time incurred to the group, otherwise 1246 * if there are mutiple queues in the group, each can dispatch 1247 * a single request on seeky media and cause lots of seek time 1248 * and group will never know it. 1249 */ 1250 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 1251 1); 1252 } else { 1253 slice_used = jiffies - cfqq->slice_start; 1254 if (slice_used > cfqq->allocated_slice) { 1255 *unaccounted_time = slice_used - cfqq->allocated_slice; 1256 slice_used = cfqq->allocated_slice; 1257 } 1258 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 1259 *unaccounted_time += cfqq->slice_start - 1260 cfqq->dispatch_start; 1261 } 1262 1263 return slice_used; 1264} 1265 1266static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 1267 struct cfq_queue *cfqq) 1268{ 1269 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1270 unsigned int used_sl, charge, unaccounted_sl = 0; 1271 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 1272 - cfqg->service_tree_idle.count; 1273 1274 BUG_ON(nr_sync < 0); 1275 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 1276 1277 if (iops_mode(cfqd)) 1278 charge = cfqq->slice_dispatch; 1279 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 1280 charge = cfqq->allocated_slice; 1281 1282 /* Can't update vdisktime while group is on service tree */ 1283 cfq_group_service_tree_del(st, cfqg); 1284 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 1285 /* If a new weight was requested, update now, off tree */ 1286 cfq_group_service_tree_add(st, cfqg); 1287 1288 /* This group is being expired. Save the context */ 1289 if (time_after(cfqd->workload_expires, jiffies)) { 1290 cfqg->saved_workload_slice = cfqd->workload_expires 1291 - jiffies; 1292 cfqg->saved_workload = cfqd->serving_type; 1293 cfqg->saved_serving_prio = cfqd->serving_prio; 1294 } else 1295 cfqg->saved_workload_slice = 0; 1296 1297 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 1298 st->min_vdisktime); 1299 cfq_log_cfqq(cfqq->cfqd, cfqq, 1300 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 1301 used_sl, cfqq->slice_dispatch, charge, 1302 iops_mode(cfqd), cfqq->nr_sectors); 1303 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl); 1304 cfqg_stats_set_start_empty_time(cfqg); 1305} 1306 1307/** 1308 * cfq_init_cfqg_base - initialize base part of a cfq_group 1309 * @cfqg: cfq_group to initialize 1310 * 1311 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED 1312 * is enabled or not. 1313 */ 1314static void cfq_init_cfqg_base(struct cfq_group *cfqg) 1315{ 1316 struct cfq_rb_root *st; 1317 int i, j; 1318 1319 for_each_cfqg_st(cfqg, i, j, st) 1320 *st = CFQ_RB_ROOT; 1321 RB_CLEAR_NODE(&cfqg->rb_node); 1322 1323 cfqg->ttime.last_end_request = jiffies; 1324} 1325 1326#ifdef CONFIG_CFQ_GROUP_IOSCHED 1327static void cfq_init_blkio_group(struct blkio_group *blkg) 1328{ 1329 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1330 1331 cfq_init_cfqg_base(cfqg); 1332 cfqg->weight = blkg->blkcg->cfq_weight; 1333} 1334 1335/* 1336 * Search for the cfq group current task belongs to. request_queue lock must 1337 * be held. 1338 */ 1339static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1340 struct blkio_cgroup *blkcg) 1341{ 1342 struct request_queue *q = cfqd->queue; 1343 struct cfq_group *cfqg = NULL; 1344 1345 /* avoid lookup for the common case where there's no blkio cgroup */ 1346 if (blkcg == &blkio_root_cgroup) { 1347 cfqg = cfqd->root_group; 1348 } else { 1349 struct blkio_group *blkg; 1350 1351 blkg = blkg_lookup_create(blkcg, q); 1352 if (!IS_ERR(blkg)) 1353 cfqg = blkg_to_cfqg(blkg); 1354 } 1355 1356 return cfqg; 1357} 1358 1359static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1360{ 1361 /* Currently, all async queues are mapped to root group */ 1362 if (!cfq_cfqq_sync(cfqq)) 1363 cfqg = cfqq->cfqd->root_group; 1364 1365 cfqq->cfqg = cfqg; 1366 /* cfqq reference on cfqg */ 1367 cfqg_get(cfqg); 1368} 1369 1370static u64 cfqg_prfill_weight_device(struct seq_file *sf, void *pdata, int off) 1371{ 1372 struct cfq_group *cfqg = pdata; 1373 1374 if (!cfqg->dev_weight) 1375 return 0; 1376 return __blkg_prfill_u64(sf, pdata, cfqg->dev_weight); 1377} 1378 1379static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft, 1380 struct seq_file *sf) 1381{ 1382 blkcg_print_blkgs(sf, cgroup_to_blkio_cgroup(cgrp), 1383 cfqg_prfill_weight_device, &blkio_policy_cfq, 0, 1384 false); 1385 return 0; 1386} 1387 1388static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft, 1389 struct seq_file *sf) 1390{ 1391 seq_printf(sf, "%u\n", cgroup_to_blkio_cgroup(cgrp)->cfq_weight); 1392 return 0; 1393} 1394 1395static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft, 1396 const char *buf) 1397{ 1398 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); 1399 struct blkg_conf_ctx ctx; 1400 struct cfq_group *cfqg; 1401 int ret; 1402 1403 ret = blkg_conf_prep(blkcg, &blkio_policy_cfq, buf, &ctx); 1404 if (ret) 1405 return ret; 1406 1407 ret = -EINVAL; 1408 cfqg = blkg_to_cfqg(ctx.blkg); 1409 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) { 1410 cfqg->dev_weight = ctx.v; 1411 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight; 1412 ret = 0; 1413 } 1414 1415 blkg_conf_finish(&ctx); 1416 return ret; 1417} 1418 1419static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val) 1420{ 1421 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); 1422 struct blkio_group *blkg; 1423 struct hlist_node *n; 1424 1425 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX) 1426 return -EINVAL; 1427 1428 spin_lock_irq(&blkcg->lock); 1429 blkcg->cfq_weight = (unsigned int)val; 1430 1431 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { 1432 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1433 1434 if (cfqg && !cfqg->dev_weight) 1435 cfqg->new_weight = blkcg->cfq_weight; 1436 } 1437 1438 spin_unlock_irq(&blkcg->lock); 1439 return 0; 1440} 1441 1442static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft, 1443 struct seq_file *sf) 1444{ 1445 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); 1446 1447 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkio_policy_cfq, 1448 cft->private, false); 1449 return 0; 1450} 1451 1452static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft, 1453 struct seq_file *sf) 1454{ 1455 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); 1456 1457 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkio_policy_cfq, 1458 cft->private, true); 1459 return 0; 1460} 1461 1462#ifdef CONFIG_DEBUG_BLK_CGROUP 1463static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, void *pdata, int off) 1464{ 1465 struct cfq_group *cfqg = pdata; 1466 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples); 1467 u64 v = 0; 1468 1469 if (samples) { 1470 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum); 1471 do_div(v, samples); 1472 } 1473 __blkg_prfill_u64(sf, pdata, v); 1474 return 0; 1475} 1476 1477/* print avg_queue_size */ 1478static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft, 1479 struct seq_file *sf) 1480{ 1481 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); 1482 1483 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size, 1484 &blkio_policy_cfq, 0, false); 1485 return 0; 1486} 1487#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1488 1489static struct cftype cfq_blkcg_files[] = { 1490 { 1491 .name = "weight_device", 1492 .read_seq_string = cfqg_print_weight_device, 1493 .write_string = cfqg_set_weight_device, 1494 .max_write_len = 256, 1495 }, 1496 { 1497 .name = "weight", 1498 .read_seq_string = cfq_print_weight, 1499 .write_u64 = cfq_set_weight, 1500 }, 1501 { 1502 .name = "time", 1503 .private = offsetof(struct cfq_group, stats.time), 1504 .read_seq_string = cfqg_print_stat, 1505 }, 1506 { 1507 .name = "sectors", 1508 .private = offsetof(struct cfq_group, stats.sectors), 1509 .read_seq_string = cfqg_print_stat, 1510 }, 1511 { 1512 .name = "io_service_bytes", 1513 .private = offsetof(struct cfq_group, stats.service_bytes), 1514 .read_seq_string = cfqg_print_rwstat, 1515 }, 1516 { 1517 .name = "io_serviced", 1518 .private = offsetof(struct cfq_group, stats.serviced), 1519 .read_seq_string = cfqg_print_rwstat, 1520 }, 1521 { 1522 .name = "io_service_time", 1523 .private = offsetof(struct cfq_group, stats.service_time), 1524 .read_seq_string = cfqg_print_rwstat, 1525 }, 1526 { 1527 .name = "io_wait_time", 1528 .private = offsetof(struct cfq_group, stats.wait_time), 1529 .read_seq_string = cfqg_print_rwstat, 1530 }, 1531 { 1532 .name = "io_merged", 1533 .private = offsetof(struct cfq_group, stats.merged), 1534 .read_seq_string = cfqg_print_rwstat, 1535 }, 1536 { 1537 .name = "io_queued", 1538 .private = offsetof(struct cfq_group, stats.queued), 1539 .read_seq_string = cfqg_print_rwstat, 1540 }, 1541#ifdef CONFIG_DEBUG_BLK_CGROUP 1542 { 1543 .name = "avg_queue_size", 1544 .read_seq_string = cfqg_print_avg_queue_size, 1545 }, 1546 { 1547 .name = "group_wait_time", 1548 .private = offsetof(struct cfq_group, stats.group_wait_time), 1549 .read_seq_string = cfqg_print_stat, 1550 }, 1551 { 1552 .name = "idle_time", 1553 .private = offsetof(struct cfq_group, stats.idle_time), 1554 .read_seq_string = cfqg_print_stat, 1555 }, 1556 { 1557 .name = "empty_time", 1558 .private = offsetof(struct cfq_group, stats.empty_time), 1559 .read_seq_string = cfqg_print_stat, 1560 }, 1561 { 1562 .name = "dequeue", 1563 .private = offsetof(struct cfq_group, stats.dequeue), 1564 .read_seq_string = cfqg_print_stat, 1565 }, 1566 { 1567 .name = "unaccounted_time", 1568 .private = offsetof(struct cfq_group, stats.unaccounted_time), 1569 .read_seq_string = cfqg_print_stat, 1570 }, 1571#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1572 { } /* terminate */ 1573}; 1574#else /* GROUP_IOSCHED */ 1575static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1576 struct blkio_cgroup *blkcg) 1577{ 1578 return cfqd->root_group; 1579} 1580 1581static inline void 1582cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1583 cfqq->cfqg = cfqg; 1584} 1585 1586#endif /* GROUP_IOSCHED */ 1587 1588/* 1589 * The cfqd->service_trees holds all pending cfq_queue's that have 1590 * requests waiting to be processed. It is sorted in the order that 1591 * we will service the queues. 1592 */ 1593static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1594 bool add_front) 1595{ 1596 struct rb_node **p, *parent; 1597 struct cfq_queue *__cfqq; 1598 unsigned long rb_key; 1599 struct cfq_rb_root *service_tree; 1600 int left; 1601 int new_cfqq = 1; 1602 1603 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1604 cfqq_type(cfqq)); 1605 if (cfq_class_idle(cfqq)) { 1606 rb_key = CFQ_IDLE_DELAY; 1607 parent = rb_last(&service_tree->rb); 1608 if (parent && parent != &cfqq->rb_node) { 1609 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1610 rb_key += __cfqq->rb_key; 1611 } else 1612 rb_key += jiffies; 1613 } else if (!add_front) { 1614 /* 1615 * Get our rb key offset. Subtract any residual slice 1616 * value carried from last service. A negative resid 1617 * count indicates slice overrun, and this should position 1618 * the next service time further away in the tree. 1619 */ 1620 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1621 rb_key -= cfqq->slice_resid; 1622 cfqq->slice_resid = 0; 1623 } else { 1624 rb_key = -HZ; 1625 __cfqq = cfq_rb_first(service_tree); 1626 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1627 } 1628 1629 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1630 new_cfqq = 0; 1631 /* 1632 * same position, nothing more to do 1633 */ 1634 if (rb_key == cfqq->rb_key && 1635 cfqq->service_tree == service_tree) 1636 return; 1637 1638 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1639 cfqq->service_tree = NULL; 1640 } 1641 1642 left = 1; 1643 parent = NULL; 1644 cfqq->service_tree = service_tree; 1645 p = &service_tree->rb.rb_node; 1646 while (*p) { 1647 struct rb_node **n; 1648 1649 parent = *p; 1650 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1651 1652 /* 1653 * sort by key, that represents service time. 1654 */ 1655 if (time_before(rb_key, __cfqq->rb_key)) 1656 n = &(*p)->rb_left; 1657 else { 1658 n = &(*p)->rb_right; 1659 left = 0; 1660 } 1661 1662 p = n; 1663 } 1664 1665 if (left) 1666 service_tree->left = &cfqq->rb_node; 1667 1668 cfqq->rb_key = rb_key; 1669 rb_link_node(&cfqq->rb_node, parent, p); 1670 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1671 service_tree->count++; 1672 if (add_front || !new_cfqq) 1673 return; 1674 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1675} 1676 1677static struct cfq_queue * 1678cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1679 sector_t sector, struct rb_node **ret_parent, 1680 struct rb_node ***rb_link) 1681{ 1682 struct rb_node **p, *parent; 1683 struct cfq_queue *cfqq = NULL; 1684 1685 parent = NULL; 1686 p = &root->rb_node; 1687 while (*p) { 1688 struct rb_node **n; 1689 1690 parent = *p; 1691 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1692 1693 /* 1694 * Sort strictly based on sector. Smallest to the left, 1695 * largest to the right. 1696 */ 1697 if (sector > blk_rq_pos(cfqq->next_rq)) 1698 n = &(*p)->rb_right; 1699 else if (sector < blk_rq_pos(cfqq->next_rq)) 1700 n = &(*p)->rb_left; 1701 else 1702 break; 1703 p = n; 1704 cfqq = NULL; 1705 } 1706 1707 *ret_parent = parent; 1708 if (rb_link) 1709 *rb_link = p; 1710 return cfqq; 1711} 1712 1713static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1714{ 1715 struct rb_node **p, *parent; 1716 struct cfq_queue *__cfqq; 1717 1718 if (cfqq->p_root) { 1719 rb_erase(&cfqq->p_node, cfqq->p_root); 1720 cfqq->p_root = NULL; 1721 } 1722 1723 if (cfq_class_idle(cfqq)) 1724 return; 1725 if (!cfqq->next_rq) 1726 return; 1727 1728 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1729 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1730 blk_rq_pos(cfqq->next_rq), &parent, &p); 1731 if (!__cfqq) { 1732 rb_link_node(&cfqq->p_node, parent, p); 1733 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1734 } else 1735 cfqq->p_root = NULL; 1736} 1737 1738/* 1739 * Update cfqq's position in the service tree. 1740 */ 1741static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1742{ 1743 /* 1744 * Resorting requires the cfqq to be on the RR list already. 1745 */ 1746 if (cfq_cfqq_on_rr(cfqq)) { 1747 cfq_service_tree_add(cfqd, cfqq, 0); 1748 cfq_prio_tree_add(cfqd, cfqq); 1749 } 1750} 1751 1752/* 1753 * add to busy list of queues for service, trying to be fair in ordering 1754 * the pending list according to last request service 1755 */ 1756static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1757{ 1758 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1759 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1760 cfq_mark_cfqq_on_rr(cfqq); 1761 cfqd->busy_queues++; 1762 if (cfq_cfqq_sync(cfqq)) 1763 cfqd->busy_sync_queues++; 1764 1765 cfq_resort_rr_list(cfqd, cfqq); 1766} 1767 1768/* 1769 * Called when the cfqq no longer has requests pending, remove it from 1770 * the service tree. 1771 */ 1772static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1773{ 1774 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1775 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1776 cfq_clear_cfqq_on_rr(cfqq); 1777 1778 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1779 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1780 cfqq->service_tree = NULL; 1781 } 1782 if (cfqq->p_root) { 1783 rb_erase(&cfqq->p_node, cfqq->p_root); 1784 cfqq->p_root = NULL; 1785 } 1786 1787 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1788 BUG_ON(!cfqd->busy_queues); 1789 cfqd->busy_queues--; 1790 if (cfq_cfqq_sync(cfqq)) 1791 cfqd->busy_sync_queues--; 1792} 1793 1794/* 1795 * rb tree support functions 1796 */ 1797static void cfq_del_rq_rb(struct request *rq) 1798{ 1799 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1800 const int sync = rq_is_sync(rq); 1801 1802 BUG_ON(!cfqq->queued[sync]); 1803 cfqq->queued[sync]--; 1804 1805 elv_rb_del(&cfqq->sort_list, rq); 1806 1807 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1808 /* 1809 * Queue will be deleted from service tree when we actually 1810 * expire it later. Right now just remove it from prio tree 1811 * as it is empty. 1812 */ 1813 if (cfqq->p_root) { 1814 rb_erase(&cfqq->p_node, cfqq->p_root); 1815 cfqq->p_root = NULL; 1816 } 1817 } 1818} 1819 1820static void cfq_add_rq_rb(struct request *rq) 1821{ 1822 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1823 struct cfq_data *cfqd = cfqq->cfqd; 1824 struct request *prev; 1825 1826 cfqq->queued[rq_is_sync(rq)]++; 1827 1828 elv_rb_add(&cfqq->sort_list, rq); 1829 1830 if (!cfq_cfqq_on_rr(cfqq)) 1831 cfq_add_cfqq_rr(cfqd, cfqq); 1832 1833 /* 1834 * check if this request is a better next-serve candidate 1835 */ 1836 prev = cfqq->next_rq; 1837 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1838 1839 /* 1840 * adjust priority tree position, if ->next_rq changes 1841 */ 1842 if (prev != cfqq->next_rq) 1843 cfq_prio_tree_add(cfqd, cfqq); 1844 1845 BUG_ON(!cfqq->next_rq); 1846} 1847 1848static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1849{ 1850 elv_rb_del(&cfqq->sort_list, rq); 1851 cfqq->queued[rq_is_sync(rq)]--; 1852 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 1853 cfq_add_rq_rb(rq); 1854 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group, 1855 rq->cmd_flags); 1856} 1857 1858static struct request * 1859cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1860{ 1861 struct task_struct *tsk = current; 1862 struct cfq_io_cq *cic; 1863 struct cfq_queue *cfqq; 1864 1865 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1866 if (!cic) 1867 return NULL; 1868 1869 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1870 if (cfqq) { 1871 sector_t sector = bio->bi_sector + bio_sectors(bio); 1872 1873 return elv_rb_find(&cfqq->sort_list, sector); 1874 } 1875 1876 return NULL; 1877} 1878 1879static void cfq_activate_request(struct request_queue *q, struct request *rq) 1880{ 1881 struct cfq_data *cfqd = q->elevator->elevator_data; 1882 1883 cfqd->rq_in_driver++; 1884 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1885 cfqd->rq_in_driver); 1886 1887 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1888} 1889 1890static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1891{ 1892 struct cfq_data *cfqd = q->elevator->elevator_data; 1893 1894 WARN_ON(!cfqd->rq_in_driver); 1895 cfqd->rq_in_driver--; 1896 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1897 cfqd->rq_in_driver); 1898} 1899 1900static void cfq_remove_request(struct request *rq) 1901{ 1902 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1903 1904 if (cfqq->next_rq == rq) 1905 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1906 1907 list_del_init(&rq->queuelist); 1908 cfq_del_rq_rb(rq); 1909 1910 cfqq->cfqd->rq_queued--; 1911 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 1912 if (rq->cmd_flags & REQ_PRIO) { 1913 WARN_ON(!cfqq->prio_pending); 1914 cfqq->prio_pending--; 1915 } 1916} 1917 1918static int cfq_merge(struct request_queue *q, struct request **req, 1919 struct bio *bio) 1920{ 1921 struct cfq_data *cfqd = q->elevator->elevator_data; 1922 struct request *__rq; 1923 1924 __rq = cfq_find_rq_fmerge(cfqd, bio); 1925 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1926 *req = __rq; 1927 return ELEVATOR_FRONT_MERGE; 1928 } 1929 1930 return ELEVATOR_NO_MERGE; 1931} 1932 1933static void cfq_merged_request(struct request_queue *q, struct request *req, 1934 int type) 1935{ 1936 if (type == ELEVATOR_FRONT_MERGE) { 1937 struct cfq_queue *cfqq = RQ_CFQQ(req); 1938 1939 cfq_reposition_rq_rb(cfqq, req); 1940 } 1941} 1942 1943static void cfq_bio_merged(struct request_queue *q, struct request *req, 1944 struct bio *bio) 1945{ 1946 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw); 1947} 1948 1949static void 1950cfq_merged_requests(struct request_queue *q, struct request *rq, 1951 struct request *next) 1952{ 1953 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1954 struct cfq_data *cfqd = q->elevator->elevator_data; 1955 1956 /* 1957 * reposition in fifo if next is older than rq 1958 */ 1959 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1960 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1961 list_move(&rq->queuelist, &next->queuelist); 1962 rq_set_fifo_time(rq, rq_fifo_time(next)); 1963 } 1964 1965 if (cfqq->next_rq == next) 1966 cfqq->next_rq = rq; 1967 cfq_remove_request(next); 1968 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags); 1969 1970 cfqq = RQ_CFQQ(next); 1971 /* 1972 * all requests of this queue are merged to other queues, delete it 1973 * from the service tree. If it's the active_queue, 1974 * cfq_dispatch_requests() will choose to expire it or do idle 1975 */ 1976 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && 1977 cfqq != cfqd->active_queue) 1978 cfq_del_cfqq_rr(cfqd, cfqq); 1979} 1980 1981static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1982 struct bio *bio) 1983{ 1984 struct cfq_data *cfqd = q->elevator->elevator_data; 1985 struct cfq_io_cq *cic; 1986 struct cfq_queue *cfqq; 1987 1988 /* 1989 * Disallow merge of a sync bio into an async request. 1990 */ 1991 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1992 return false; 1993 1994 /* 1995 * Lookup the cfqq that this bio will be queued with and allow 1996 * merge only if rq is queued there. 1997 */ 1998 cic = cfq_cic_lookup(cfqd, current->io_context); 1999 if (!cic) 2000 return false; 2001 2002 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 2003 return cfqq == RQ_CFQQ(rq); 2004} 2005 2006static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2007{ 2008 del_timer(&cfqd->idle_slice_timer); 2009 cfqg_stats_update_idle_time(cfqq->cfqg); 2010} 2011 2012static void __cfq_set_active_queue(struct cfq_data *cfqd, 2013 struct cfq_queue *cfqq) 2014{ 2015 if (cfqq) { 2016 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 2017 cfqd->serving_prio, cfqd->serving_type); 2018 cfqg_stats_update_avg_queue_size(cfqq->cfqg); 2019 cfqq->slice_start = 0; 2020 cfqq->dispatch_start = jiffies; 2021 cfqq->allocated_slice = 0; 2022 cfqq->slice_end = 0; 2023 cfqq->slice_dispatch = 0; 2024 cfqq->nr_sectors = 0; 2025 2026 cfq_clear_cfqq_wait_request(cfqq); 2027 cfq_clear_cfqq_must_dispatch(cfqq); 2028 cfq_clear_cfqq_must_alloc_slice(cfqq); 2029 cfq_clear_cfqq_fifo_expire(cfqq); 2030 cfq_mark_cfqq_slice_new(cfqq); 2031 2032 cfq_del_timer(cfqd, cfqq); 2033 } 2034 2035 cfqd->active_queue = cfqq; 2036} 2037 2038/* 2039 * current cfqq expired its slice (or was too idle), select new one 2040 */ 2041static void 2042__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2043 bool timed_out) 2044{ 2045 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 2046 2047 if (cfq_cfqq_wait_request(cfqq)) 2048 cfq_del_timer(cfqd, cfqq); 2049 2050 cfq_clear_cfqq_wait_request(cfqq); 2051 cfq_clear_cfqq_wait_busy(cfqq); 2052 2053 /* 2054 * If this cfqq is shared between multiple processes, check to 2055 * make sure that those processes are still issuing I/Os within 2056 * the mean seek distance. If not, it may be time to break the 2057 * queues apart again. 2058 */ 2059 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 2060 cfq_mark_cfqq_split_coop(cfqq); 2061 2062 /* 2063 * store what was left of this slice, if the queue idled/timed out 2064 */ 2065 if (timed_out) { 2066 if (cfq_cfqq_slice_new(cfqq)) 2067 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 2068 else 2069 cfqq->slice_resid = cfqq->slice_end - jiffies; 2070 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 2071 } 2072 2073 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 2074 2075 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 2076 cfq_del_cfqq_rr(cfqd, cfqq); 2077 2078 cfq_resort_rr_list(cfqd, cfqq); 2079 2080 if (cfqq == cfqd->active_queue) 2081 cfqd->active_queue = NULL; 2082 2083 if (cfqd->active_cic) { 2084 put_io_context(cfqd->active_cic->icq.ioc); 2085 cfqd->active_cic = NULL; 2086 } 2087} 2088 2089static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 2090{ 2091 struct cfq_queue *cfqq = cfqd->active_queue; 2092 2093 if (cfqq) 2094 __cfq_slice_expired(cfqd, cfqq, timed_out); 2095} 2096 2097/* 2098 * Get next queue for service. Unless we have a queue preemption, 2099 * we'll simply select the first cfqq in the service tree. 2100 */ 2101static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 2102{ 2103 struct cfq_rb_root *service_tree = 2104 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 2105 cfqd->serving_type); 2106 2107 if (!cfqd->rq_queued) 2108 return NULL; 2109 2110 /* There is nothing to dispatch */ 2111 if (!service_tree) 2112 return NULL; 2113 if (RB_EMPTY_ROOT(&service_tree->rb)) 2114 return NULL; 2115 return cfq_rb_first(service_tree); 2116} 2117 2118static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 2119{ 2120 struct cfq_group *cfqg; 2121 struct cfq_queue *cfqq; 2122 int i, j; 2123 struct cfq_rb_root *st; 2124 2125 if (!cfqd->rq_queued) 2126 return NULL; 2127 2128 cfqg = cfq_get_next_cfqg(cfqd); 2129 if (!cfqg) 2130 return NULL; 2131 2132 for_each_cfqg_st(cfqg, i, j, st) 2133 if ((cfqq = cfq_rb_first(st)) != NULL) 2134 return cfqq; 2135 return NULL; 2136} 2137 2138/* 2139 * Get and set a new active queue for service. 2140 */ 2141static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 2142 struct cfq_queue *cfqq) 2143{ 2144 if (!cfqq) 2145 cfqq = cfq_get_next_queue(cfqd); 2146 2147 __cfq_set_active_queue(cfqd, cfqq); 2148 return cfqq; 2149} 2150 2151static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 2152 struct request *rq) 2153{ 2154 if (blk_rq_pos(rq) >= cfqd->last_position) 2155 return blk_rq_pos(rq) - cfqd->last_position; 2156 else 2157 return cfqd->last_position - blk_rq_pos(rq); 2158} 2159 2160static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2161 struct request *rq) 2162{ 2163 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 2164} 2165 2166static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 2167 struct cfq_queue *cur_cfqq) 2168{ 2169 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 2170 struct rb_node *parent, *node; 2171 struct cfq_queue *__cfqq; 2172 sector_t sector = cfqd->last_position; 2173 2174 if (RB_EMPTY_ROOT(root)) 2175 return NULL; 2176 2177 /* 2178 * First, if we find a request starting at the end of the last 2179 * request, choose it. 2180 */ 2181 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 2182 if (__cfqq) 2183 return __cfqq; 2184 2185 /* 2186 * If the exact sector wasn't found, the parent of the NULL leaf 2187 * will contain the closest sector. 2188 */ 2189 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 2190 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2191 return __cfqq; 2192 2193 if (blk_rq_pos(__cfqq->next_rq) < sector) 2194 node = rb_next(&__cfqq->p_node); 2195 else 2196 node = rb_prev(&__cfqq->p_node); 2197 if (!node) 2198 return NULL; 2199 2200 __cfqq = rb_entry(node, struct cfq_queue, p_node); 2201 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2202 return __cfqq; 2203 2204 return NULL; 2205} 2206 2207/* 2208 * cfqd - obvious 2209 * cur_cfqq - passed in so that we don't decide that the current queue is 2210 * closely cooperating with itself. 2211 * 2212 * So, basically we're assuming that that cur_cfqq has dispatched at least 2213 * one request, and that cfqd->last_position reflects a position on the disk 2214 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 2215 * assumption. 2216 */ 2217static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 2218 struct cfq_queue *cur_cfqq) 2219{ 2220 struct cfq_queue *cfqq; 2221 2222 if (cfq_class_idle(cur_cfqq)) 2223 return NULL; 2224 if (!cfq_cfqq_sync(cur_cfqq)) 2225 return NULL; 2226 if (CFQQ_SEEKY(cur_cfqq)) 2227 return NULL; 2228 2229 /* 2230 * Don't search priority tree if it's the only queue in the group. 2231 */ 2232 if (cur_cfqq->cfqg->nr_cfqq == 1) 2233 return NULL; 2234 2235 /* 2236 * We should notice if some of the queues are cooperating, eg 2237 * working closely on the same area of the disk. In that case, 2238 * we can group them together and don't waste time idling. 2239 */ 2240 cfqq = cfqq_close(cfqd, cur_cfqq); 2241 if (!cfqq) 2242 return NULL; 2243 2244 /* If new queue belongs to different cfq_group, don't choose it */ 2245 if (cur_cfqq->cfqg != cfqq->cfqg) 2246 return NULL; 2247 2248 /* 2249 * It only makes sense to merge sync queues. 2250 */ 2251 if (!cfq_cfqq_sync(cfqq)) 2252 return NULL; 2253 if (CFQQ_SEEKY(cfqq)) 2254 return NULL; 2255 2256 /* 2257 * Do not merge queues of different priority classes 2258 */ 2259 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 2260 return NULL; 2261 2262 return cfqq; 2263} 2264 2265/* 2266 * Determine whether we should enforce idle window for this queue. 2267 */ 2268 2269static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2270{ 2271 enum wl_prio_t prio = cfqq_prio(cfqq); 2272 struct cfq_rb_root *service_tree = cfqq->service_tree; 2273 2274 BUG_ON(!service_tree); 2275 BUG_ON(!service_tree->count); 2276 2277 if (!cfqd->cfq_slice_idle) 2278 return false; 2279 2280 /* We never do for idle class queues. */ 2281 if (prio == IDLE_WORKLOAD) 2282 return false; 2283 2284 /* We do for queues that were marked with idle window flag. */ 2285 if (cfq_cfqq_idle_window(cfqq) && 2286 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 2287 return true; 2288 2289 /* 2290 * Otherwise, we do only if they are the last ones 2291 * in their service tree. 2292 */ 2293 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) && 2294 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false)) 2295 return true; 2296 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 2297 service_tree->count); 2298 return false; 2299} 2300 2301static void cfq_arm_slice_timer(struct cfq_data *cfqd) 2302{ 2303 struct cfq_queue *cfqq = cfqd->active_queue; 2304 struct cfq_io_cq *cic; 2305 unsigned long sl, group_idle = 0; 2306 2307 /* 2308 * SSD device without seek penalty, disable idling. But only do so 2309 * for devices that support queuing, otherwise we still have a problem 2310 * with sync vs async workloads. 2311 */ 2312 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 2313 return; 2314 2315 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 2316 WARN_ON(cfq_cfqq_slice_new(cfqq)); 2317 2318 /* 2319 * idle is disabled, either manually or by past process history 2320 */ 2321 if (!cfq_should_idle(cfqd, cfqq)) { 2322 /* no queue idling. Check for group idling */ 2323 if (cfqd->cfq_group_idle) 2324 group_idle = cfqd->cfq_group_idle; 2325 else 2326 return; 2327 } 2328 2329 /* 2330 * still active requests from this queue, don't idle 2331 */ 2332 if (cfqq->dispatched) 2333 return; 2334 2335 /* 2336 * task has exited, don't wait 2337 */ 2338 cic = cfqd->active_cic; 2339 if (!cic || !atomic_read(&cic->icq.ioc->active_ref)) 2340 return; 2341 2342 /* 2343 * If our average think time is larger than the remaining time 2344 * slice, then don't idle. This avoids overrunning the allotted 2345 * time slice. 2346 */ 2347 if (sample_valid(cic->ttime.ttime_samples) && 2348 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { 2349 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2350 cic->ttime.ttime_mean); 2351 return; 2352 } 2353 2354 /* There are other queues in the group, don't do group idle */ 2355 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2356 return; 2357 2358 cfq_mark_cfqq_wait_request(cfqq); 2359 2360 if (group_idle) 2361 sl = cfqd->cfq_group_idle; 2362 else 2363 sl = cfqd->cfq_slice_idle; 2364 2365 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2366 cfqg_stats_set_start_idle_time(cfqq->cfqg); 2367 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2368 group_idle ? 1 : 0); 2369} 2370 2371/* 2372 * Move request from internal lists to the request queue dispatch list. 2373 */ 2374static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2375{ 2376 struct cfq_data *cfqd = q->elevator->elevator_data; 2377 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2378 2379 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2380 2381 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2382 cfq_remove_request(rq); 2383 cfqq->dispatched++; 2384 (RQ_CFQG(rq))->dispatched++; 2385 elv_dispatch_sort(q, rq); 2386 2387 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2388 cfqq->nr_sectors += blk_rq_sectors(rq); 2389 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags); 2390} 2391 2392/* 2393 * return expired entry, or NULL to just start from scratch in rbtree 2394 */ 2395static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2396{ 2397 struct request *rq = NULL; 2398 2399 if (cfq_cfqq_fifo_expire(cfqq)) 2400 return NULL; 2401 2402 cfq_mark_cfqq_fifo_expire(cfqq); 2403 2404 if (list_empty(&cfqq->fifo)) 2405 return NULL; 2406 2407 rq = rq_entry_fifo(cfqq->fifo.next); 2408 if (time_before(jiffies, rq_fifo_time(rq))) 2409 rq = NULL; 2410 2411 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2412 return rq; 2413} 2414 2415static inline int 2416cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2417{ 2418 const int base_rq = cfqd->cfq_slice_async_rq; 2419 2420 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2421 2422 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2423} 2424 2425/* 2426 * Must be called with the queue_lock held. 2427 */ 2428static int cfqq_process_refs(struct cfq_queue *cfqq) 2429{ 2430 int process_refs, io_refs; 2431 2432 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2433 process_refs = cfqq->ref - io_refs; 2434 BUG_ON(process_refs < 0); 2435 return process_refs; 2436} 2437 2438static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2439{ 2440 int process_refs, new_process_refs; 2441 struct cfq_queue *__cfqq; 2442 2443 /* 2444 * If there are no process references on the new_cfqq, then it is 2445 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2446 * chain may have dropped their last reference (not just their 2447 * last process reference). 2448 */ 2449 if (!cfqq_process_refs(new_cfqq)) 2450 return; 2451 2452 /* Avoid a circular list and skip interim queue merges */ 2453 while ((__cfqq = new_cfqq->new_cfqq)) { 2454 if (__cfqq == cfqq) 2455 return; 2456 new_cfqq = __cfqq; 2457 } 2458 2459 process_refs = cfqq_process_refs(cfqq); 2460 new_process_refs = cfqq_process_refs(new_cfqq); 2461 /* 2462 * If the process for the cfqq has gone away, there is no 2463 * sense in merging the queues. 2464 */ 2465 if (process_refs == 0 || new_process_refs == 0) 2466 return; 2467 2468 /* 2469 * Merge in the direction of the lesser amount of work. 2470 */ 2471 if (new_process_refs >= process_refs) { 2472 cfqq->new_cfqq = new_cfqq; 2473 new_cfqq->ref += process_refs; 2474 } else { 2475 new_cfqq->new_cfqq = cfqq; 2476 cfqq->ref += new_process_refs; 2477 } 2478} 2479 2480static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 2481 struct cfq_group *cfqg, enum wl_prio_t prio) 2482{ 2483 struct cfq_queue *queue; 2484 int i; 2485 bool key_valid = false; 2486 unsigned long lowest_key = 0; 2487 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2488 2489 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2490 /* select the one with lowest rb_key */ 2491 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2492 if (queue && 2493 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2494 lowest_key = queue->rb_key; 2495 cur_best = i; 2496 key_valid = true; 2497 } 2498 } 2499 2500 return cur_best; 2501} 2502 2503static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2504{ 2505 unsigned slice; 2506 unsigned count; 2507 struct cfq_rb_root *st; 2508 unsigned group_slice; 2509 enum wl_prio_t original_prio = cfqd->serving_prio; 2510 2511 /* Choose next priority. RT > BE > IDLE */ 2512 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2513 cfqd->serving_prio = RT_WORKLOAD; 2514 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2515 cfqd->serving_prio = BE_WORKLOAD; 2516 else { 2517 cfqd->serving_prio = IDLE_WORKLOAD; 2518 cfqd->workload_expires = jiffies + 1; 2519 return; 2520 } 2521 2522 if (original_prio != cfqd->serving_prio) 2523 goto new_workload; 2524 2525 /* 2526 * For RT and BE, we have to choose also the type 2527 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2528 * expiration time 2529 */ 2530 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2531 count = st->count; 2532 2533 /* 2534 * check workload expiration, and that we still have other queues ready 2535 */ 2536 if (count && !time_after(jiffies, cfqd->workload_expires)) 2537 return; 2538 2539new_workload: 2540 /* otherwise select new workload type */ 2541 cfqd->serving_type = 2542 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2543 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2544 count = st->count; 2545 2546 /* 2547 * the workload slice is computed as a fraction of target latency 2548 * proportional to the number of queues in that workload, over 2549 * all the queues in the same priority class 2550 */ 2551 group_slice = cfq_group_slice(cfqd, cfqg); 2552 2553 slice = group_slice * count / 2554 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2555 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2556 2557 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2558 unsigned int tmp; 2559 2560 /* 2561 * Async queues are currently system wide. Just taking 2562 * proportion of queues with-in same group will lead to higher 2563 * async ratio system wide as generally root group is going 2564 * to have higher weight. A more accurate thing would be to 2565 * calculate system wide asnc/sync ratio. 2566 */ 2567 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2568 tmp = tmp/cfqd->busy_queues; 2569 slice = min_t(unsigned, slice, tmp); 2570 2571 /* async workload slice is scaled down according to 2572 * the sync/async slice ratio. */ 2573 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2574 } else 2575 /* sync workload slice is at least 2 * cfq_slice_idle */ 2576 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2577 2578 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2579 cfq_log(cfqd, "workload slice:%d", slice); 2580 cfqd->workload_expires = jiffies + slice; 2581} 2582 2583static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2584{ 2585 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2586 struct cfq_group *cfqg; 2587 2588 if (RB_EMPTY_ROOT(&st->rb)) 2589 return NULL; 2590 cfqg = cfq_rb_first_group(st); 2591 update_min_vdisktime(st); 2592 return cfqg; 2593} 2594 2595static void cfq_choose_cfqg(struct cfq_data *cfqd) 2596{ 2597 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2598 2599 cfqd->serving_group = cfqg; 2600 2601 /* Restore the workload type data */ 2602 if (cfqg->saved_workload_slice) { 2603 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2604 cfqd->serving_type = cfqg->saved_workload; 2605 cfqd->serving_prio = cfqg->saved_serving_prio; 2606 } else 2607 cfqd->workload_expires = jiffies - 1; 2608 2609 choose_service_tree(cfqd, cfqg); 2610} 2611 2612/* 2613 * Select a queue for service. If we have a current active queue, 2614 * check whether to continue servicing it, or retrieve and set a new one. 2615 */ 2616static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2617{ 2618 struct cfq_queue *cfqq, *new_cfqq = NULL; 2619 2620 cfqq = cfqd->active_queue; 2621 if (!cfqq) 2622 goto new_queue; 2623 2624 if (!cfqd->rq_queued) 2625 return NULL; 2626 2627 /* 2628 * We were waiting for group to get backlogged. Expire the queue 2629 */ 2630 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2631 goto expire; 2632 2633 /* 2634 * The active queue has run out of time, expire it and select new. 2635 */ 2636 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2637 /* 2638 * If slice had not expired at the completion of last request 2639 * we might not have turned on wait_busy flag. Don't expire 2640 * the queue yet. Allow the group to get backlogged. 2641 * 2642 * The very fact that we have used the slice, that means we 2643 * have been idling all along on this queue and it should be 2644 * ok to wait for this request to complete. 2645 */ 2646 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2647 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2648 cfqq = NULL; 2649 goto keep_queue; 2650 } else 2651 goto check_group_idle; 2652 } 2653 2654 /* 2655 * The active queue has requests and isn't expired, allow it to 2656 * dispatch. 2657 */ 2658 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2659 goto keep_queue; 2660 2661 /* 2662 * If another queue has a request waiting within our mean seek 2663 * distance, let it run. The expire code will check for close 2664 * cooperators and put the close queue at the front of the service 2665 * tree. If possible, merge the expiring queue with the new cfqq. 2666 */ 2667 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2668 if (new_cfqq) { 2669 if (!cfqq->new_cfqq) 2670 cfq_setup_merge(cfqq, new_cfqq); 2671 goto expire; 2672 } 2673 2674 /* 2675 * No requests pending. If the active queue still has requests in 2676 * flight or is idling for a new request, allow either of these 2677 * conditions to happen (or time out) before selecting a new queue. 2678 */ 2679 if (timer_pending(&cfqd->idle_slice_timer)) { 2680 cfqq = NULL; 2681 goto keep_queue; 2682 } 2683 2684 /* 2685 * This is a deep seek queue, but the device is much faster than 2686 * the queue can deliver, don't idle 2687 **/ 2688 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2689 (cfq_cfqq_slice_new(cfqq) || 2690 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2691 cfq_clear_cfqq_deep(cfqq); 2692 cfq_clear_cfqq_idle_window(cfqq); 2693 } 2694 2695 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2696 cfqq = NULL; 2697 goto keep_queue; 2698 } 2699 2700 /* 2701 * If group idle is enabled and there are requests dispatched from 2702 * this group, wait for requests to complete. 2703 */ 2704check_group_idle: 2705 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && 2706 cfqq->cfqg->dispatched && 2707 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { 2708 cfqq = NULL; 2709 goto keep_queue; 2710 } 2711 2712expire: 2713 cfq_slice_expired(cfqd, 0); 2714new_queue: 2715 /* 2716 * Current queue expired. Check if we have to switch to a new 2717 * service tree 2718 */ 2719 if (!new_cfqq) 2720 cfq_choose_cfqg(cfqd); 2721 2722 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2723keep_queue: 2724 return cfqq; 2725} 2726 2727static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2728{ 2729 int dispatched = 0; 2730 2731 while (cfqq->next_rq) { 2732 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2733 dispatched++; 2734 } 2735 2736 BUG_ON(!list_empty(&cfqq->fifo)); 2737 2738 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2739 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2740 return dispatched; 2741} 2742 2743/* 2744 * Drain our current requests. Used for barriers and when switching 2745 * io schedulers on-the-fly. 2746 */ 2747static int cfq_forced_dispatch(struct cfq_data *cfqd) 2748{ 2749 struct cfq_queue *cfqq; 2750 int dispatched = 0; 2751 2752 /* Expire the timeslice of the current active queue first */ 2753 cfq_slice_expired(cfqd, 0); 2754 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2755 __cfq_set_active_queue(cfqd, cfqq); 2756 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2757 } 2758 2759 BUG_ON(cfqd->busy_queues); 2760 2761 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2762 return dispatched; 2763} 2764 2765static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2766 struct cfq_queue *cfqq) 2767{ 2768 /* the queue hasn't finished any request, can't estimate */ 2769 if (cfq_cfqq_slice_new(cfqq)) 2770 return true; 2771 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2772 cfqq->slice_end)) 2773 return true; 2774 2775 return false; 2776} 2777 2778static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2779{ 2780 unsigned int max_dispatch; 2781 2782 /* 2783 * Drain async requests before we start sync IO 2784 */ 2785 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2786 return false; 2787 2788 /* 2789 * If this is an async queue and we have sync IO in flight, let it wait 2790 */ 2791 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2792 return false; 2793 2794 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2795 if (cfq_class_idle(cfqq)) 2796 max_dispatch = 1; 2797 2798 /* 2799 * Does this cfqq already have too much IO in flight? 2800 */ 2801 if (cfqq->dispatched >= max_dispatch) { 2802 bool promote_sync = false; 2803 /* 2804 * idle queue must always only have a single IO in flight 2805 */ 2806 if (cfq_class_idle(cfqq)) 2807 return false; 2808 2809 /* 2810 * If there is only one sync queue 2811 * we can ignore async queue here and give the sync 2812 * queue no dispatch limit. The reason is a sync queue can 2813 * preempt async queue, limiting the sync queue doesn't make 2814 * sense. This is useful for aiostress test. 2815 */ 2816 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2817 promote_sync = true; 2818 2819 /* 2820 * We have other queues, don't allow more IO from this one 2821 */ 2822 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2823 !promote_sync) 2824 return false; 2825 2826 /* 2827 * Sole queue user, no limit 2828 */ 2829 if (cfqd->busy_queues == 1 || promote_sync) 2830 max_dispatch = -1; 2831 else 2832 /* 2833 * Normally we start throttling cfqq when cfq_quantum/2 2834 * requests have been dispatched. But we can drive 2835 * deeper queue depths at the beginning of slice 2836 * subjected to upper limit of cfq_quantum. 2837 * */ 2838 max_dispatch = cfqd->cfq_quantum; 2839 } 2840 2841 /* 2842 * Async queues must wait a bit before being allowed dispatch. 2843 * We also ramp up the dispatch depth gradually for async IO, 2844 * based on the last sync IO we serviced 2845 */ 2846 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2847 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2848 unsigned int depth; 2849 2850 depth = last_sync / cfqd->cfq_slice[1]; 2851 if (!depth && !cfqq->dispatched) 2852 depth = 1; 2853 if (depth < max_dispatch) 2854 max_dispatch = depth; 2855 } 2856 2857 /* 2858 * If we're below the current max, allow a dispatch 2859 */ 2860 return cfqq->dispatched < max_dispatch; 2861} 2862 2863/* 2864 * Dispatch a request from cfqq, moving them to the request queue 2865 * dispatch list. 2866 */ 2867static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2868{ 2869 struct request *rq; 2870 2871 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2872 2873 if (!cfq_may_dispatch(cfqd, cfqq)) 2874 return false; 2875 2876 /* 2877 * follow expired path, else get first next available 2878 */ 2879 rq = cfq_check_fifo(cfqq); 2880 if (!rq) 2881 rq = cfqq->next_rq; 2882 2883 /* 2884 * insert request into driver dispatch list 2885 */ 2886 cfq_dispatch_insert(cfqd->queue, rq); 2887 2888 if (!cfqd->active_cic) { 2889 struct cfq_io_cq *cic = RQ_CIC(rq); 2890 2891 atomic_long_inc(&cic->icq.ioc->refcount); 2892 cfqd->active_cic = cic; 2893 } 2894 2895 return true; 2896} 2897 2898/* 2899 * Find the cfqq that we need to service and move a request from that to the 2900 * dispatch list 2901 */ 2902static int cfq_dispatch_requests(struct request_queue *q, int force) 2903{ 2904 struct cfq_data *cfqd = q->elevator->elevator_data; 2905 struct cfq_queue *cfqq; 2906 2907 if (!cfqd->busy_queues) 2908 return 0; 2909 2910 if (unlikely(force)) 2911 return cfq_forced_dispatch(cfqd); 2912 2913 cfqq = cfq_select_queue(cfqd); 2914 if (!cfqq) 2915 return 0; 2916 2917 /* 2918 * Dispatch a request from this cfqq, if it is allowed 2919 */ 2920 if (!cfq_dispatch_request(cfqd, cfqq)) 2921 return 0; 2922 2923 cfqq->slice_dispatch++; 2924 cfq_clear_cfqq_must_dispatch(cfqq); 2925 2926 /* 2927 * expire an async queue immediately if it has used up its slice. idle 2928 * queue always expire after 1 dispatch round. 2929 */ 2930 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2931 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2932 cfq_class_idle(cfqq))) { 2933 cfqq->slice_end = jiffies + 1; 2934 cfq_slice_expired(cfqd, 0); 2935 } 2936 2937 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2938 return 1; 2939} 2940 2941/* 2942 * task holds one reference to the queue, dropped when task exits. each rq 2943 * in-flight on this queue also holds a reference, dropped when rq is freed. 2944 * 2945 * Each cfq queue took a reference on the parent group. Drop it now. 2946 * queue lock must be held here. 2947 */ 2948static void cfq_put_queue(struct cfq_queue *cfqq) 2949{ 2950 struct cfq_data *cfqd = cfqq->cfqd; 2951 struct cfq_group *cfqg; 2952 2953 BUG_ON(cfqq->ref <= 0); 2954 2955 cfqq->ref--; 2956 if (cfqq->ref) 2957 return; 2958 2959 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2960 BUG_ON(rb_first(&cfqq->sort_list)); 2961 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2962 cfqg = cfqq->cfqg; 2963 2964 if (unlikely(cfqd->active_queue == cfqq)) { 2965 __cfq_slice_expired(cfqd, cfqq, 0); 2966 cfq_schedule_dispatch(cfqd); 2967 } 2968 2969 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2970 kmem_cache_free(cfq_pool, cfqq); 2971 cfqg_put(cfqg); 2972} 2973 2974static void cfq_put_cooperator(struct cfq_queue *cfqq) 2975{ 2976 struct cfq_queue *__cfqq, *next; 2977 2978 /* 2979 * If this queue was scheduled to merge with another queue, be 2980 * sure to drop the reference taken on that queue (and others in 2981 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2982 */ 2983 __cfqq = cfqq->new_cfqq; 2984 while (__cfqq) { 2985 if (__cfqq == cfqq) { 2986 WARN(1, "cfqq->new_cfqq loop detected\n"); 2987 break; 2988 } 2989 next = __cfqq->new_cfqq; 2990 cfq_put_queue(__cfqq); 2991 __cfqq = next; 2992 } 2993} 2994 2995static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2996{ 2997 if (unlikely(cfqq == cfqd->active_queue)) { 2998 __cfq_slice_expired(cfqd, cfqq, 0); 2999 cfq_schedule_dispatch(cfqd); 3000 } 3001 3002 cfq_put_cooperator(cfqq); 3003 3004 cfq_put_queue(cfqq); 3005} 3006 3007static void cfq_init_icq(struct io_cq *icq) 3008{ 3009 struct cfq_io_cq *cic = icq_to_cic(icq); 3010 3011 cic->ttime.last_end_request = jiffies; 3012} 3013 3014static void cfq_exit_icq(struct io_cq *icq) 3015{ 3016 struct cfq_io_cq *cic = icq_to_cic(icq); 3017 struct cfq_data *cfqd = cic_to_cfqd(cic); 3018 3019 if (cic->cfqq[BLK_RW_ASYNC]) { 3020 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 3021 cic->cfqq[BLK_RW_ASYNC] = NULL; 3022 } 3023 3024 if (cic->cfqq[BLK_RW_SYNC]) { 3025 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 3026 cic->cfqq[BLK_RW_SYNC] = NULL; 3027 } 3028} 3029 3030static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) 3031{ 3032 struct task_struct *tsk = current; 3033 int ioprio_class; 3034 3035 if (!cfq_cfqq_prio_changed(cfqq)) 3036 return; 3037 3038 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3039 switch (ioprio_class) { 3040 default: 3041 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 3042 case IOPRIO_CLASS_NONE: 3043 /* 3044 * no prio set, inherit CPU scheduling settings 3045 */ 3046 cfqq->ioprio = task_nice_ioprio(tsk); 3047 cfqq->ioprio_class = task_nice_ioclass(tsk); 3048 break; 3049 case IOPRIO_CLASS_RT: 3050 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3051 cfqq->ioprio_class = IOPRIO_CLASS_RT; 3052 break; 3053 case IOPRIO_CLASS_BE: 3054 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3055 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3056 break; 3057 case IOPRIO_CLASS_IDLE: 3058 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 3059 cfqq->ioprio = 7; 3060 cfq_clear_cfqq_idle_window(cfqq); 3061 break; 3062 } 3063 3064 /* 3065 * keep track of original prio settings in case we have to temporarily 3066 * elevate the priority of this queue 3067 */ 3068 cfqq->org_ioprio = cfqq->ioprio; 3069 cfq_clear_cfqq_prio_changed(cfqq); 3070} 3071 3072static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio) 3073{ 3074 int ioprio = cic->icq.ioc->ioprio; 3075 struct cfq_data *cfqd = cic_to_cfqd(cic); 3076 struct cfq_queue *cfqq; 3077 3078 /* 3079 * Check whether ioprio has changed. The condition may trigger 3080 * spuriously on a newly created cic but there's no harm. 3081 */ 3082 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio)) 3083 return; 3084 3085 cfqq = cic->cfqq[BLK_RW_ASYNC]; 3086 if (cfqq) { 3087 struct cfq_queue *new_cfqq; 3088 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio, 3089 GFP_ATOMIC); 3090 if (new_cfqq) { 3091 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 3092 cfq_put_queue(cfqq); 3093 } 3094 } 3095 3096 cfqq = cic->cfqq[BLK_RW_SYNC]; 3097 if (cfqq) 3098 cfq_mark_cfqq_prio_changed(cfqq); 3099 3100 cic->ioprio = ioprio; 3101} 3102 3103static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3104 pid_t pid, bool is_sync) 3105{ 3106 RB_CLEAR_NODE(&cfqq->rb_node); 3107 RB_CLEAR_NODE(&cfqq->p_node); 3108 INIT_LIST_HEAD(&cfqq->fifo); 3109 3110 cfqq->ref = 0; 3111 cfqq->cfqd = cfqd; 3112 3113 cfq_mark_cfqq_prio_changed(cfqq); 3114 3115 if (is_sync) { 3116 if (!cfq_class_idle(cfqq)) 3117 cfq_mark_cfqq_idle_window(cfqq); 3118 cfq_mark_cfqq_sync(cfqq); 3119 } 3120 cfqq->pid = pid; 3121} 3122 3123#ifdef CONFIG_CFQ_GROUP_IOSCHED 3124static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) 3125{ 3126 struct cfq_data *cfqd = cic_to_cfqd(cic); 3127 struct cfq_queue *sync_cfqq; 3128 uint64_t id; 3129 3130 rcu_read_lock(); 3131 id = bio_blkio_cgroup(bio)->id; 3132 rcu_read_unlock(); 3133 3134 /* 3135 * Check whether blkcg has changed. The condition may trigger 3136 * spuriously on a newly created cic but there's no harm. 3137 */ 3138 if (unlikely(!cfqd) || likely(cic->blkcg_id == id)) 3139 return; 3140 3141 sync_cfqq = cic_to_cfqq(cic, 1); 3142 if (sync_cfqq) { 3143 /* 3144 * Drop reference to sync queue. A new sync queue will be 3145 * assigned in new group upon arrival of a fresh request. 3146 */ 3147 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 3148 cic_set_cfqq(cic, NULL, 1); 3149 cfq_put_queue(sync_cfqq); 3150 } 3151 3152 cic->blkcg_id = id; 3153} 3154#else 3155static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { } 3156#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 3157 3158static struct cfq_queue * 3159cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3160 struct bio *bio, gfp_t gfp_mask) 3161{ 3162 struct blkio_cgroup *blkcg; 3163 struct cfq_queue *cfqq, *new_cfqq = NULL; 3164 struct cfq_group *cfqg; 3165 3166retry: 3167 rcu_read_lock(); 3168 3169 blkcg = bio_blkio_cgroup(bio); 3170 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg); 3171 cfqq = cic_to_cfqq(cic, is_sync); 3172 3173 /* 3174 * Always try a new alloc if we fell back to the OOM cfqq 3175 * originally, since it should just be a temporary situation. 3176 */ 3177 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3178 cfqq = NULL; 3179 if (new_cfqq) { 3180 cfqq = new_cfqq; 3181 new_cfqq = NULL; 3182 } else if (gfp_mask & __GFP_WAIT) { 3183 rcu_read_unlock(); 3184 spin_unlock_irq(cfqd->queue->queue_lock); 3185 new_cfqq = kmem_cache_alloc_node(cfq_pool, 3186 gfp_mask | __GFP_ZERO, 3187 cfqd->queue->node); 3188 spin_lock_irq(cfqd->queue->queue_lock); 3189 if (new_cfqq) 3190 goto retry; 3191 } else { 3192 cfqq = kmem_cache_alloc_node(cfq_pool, 3193 gfp_mask | __GFP_ZERO, 3194 cfqd->queue->node); 3195 } 3196 3197 if (cfqq) { 3198 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3199 cfq_init_prio_data(cfqq, cic); 3200 cfq_link_cfqq_cfqg(cfqq, cfqg); 3201 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3202 } else 3203 cfqq = &cfqd->oom_cfqq; 3204 } 3205 3206 if (new_cfqq) 3207 kmem_cache_free(cfq_pool, new_cfqq); 3208 3209 rcu_read_unlock(); 3210 return cfqq; 3211} 3212 3213static struct cfq_queue ** 3214cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3215{ 3216 switch (ioprio_class) { 3217 case IOPRIO_CLASS_RT: 3218 return &cfqd->async_cfqq[0][ioprio]; 3219 case IOPRIO_CLASS_NONE: 3220 ioprio = IOPRIO_NORM; 3221 /* fall through */ 3222 case IOPRIO_CLASS_BE: 3223 return &cfqd->async_cfqq[1][ioprio]; 3224 case IOPRIO_CLASS_IDLE: 3225 return &cfqd->async_idle_cfqq; 3226 default: 3227 BUG(); 3228 } 3229} 3230 3231static struct cfq_queue * 3232cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3233 struct bio *bio, gfp_t gfp_mask) 3234{ 3235 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3236 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3237 struct cfq_queue **async_cfqq = NULL; 3238 struct cfq_queue *cfqq = NULL; 3239 3240 if (!is_sync) { 3241 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3242 cfqq = *async_cfqq; 3243 } 3244 3245 if (!cfqq) 3246 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask); 3247 3248 /* 3249 * pin the queue now that it's allocated, scheduler exit will prune it 3250 */ 3251 if (!is_sync && !(*async_cfqq)) { 3252 cfqq->ref++; 3253 *async_cfqq = cfqq; 3254 } 3255 3256 cfqq->ref++; 3257 return cfqq; 3258} 3259 3260static void 3261__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) 3262{ 3263 unsigned long elapsed = jiffies - ttime->last_end_request; 3264 elapsed = min(elapsed, 2UL * slice_idle); 3265 3266 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; 3267 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; 3268 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; 3269} 3270 3271static void 3272cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3273 struct cfq_io_cq *cic) 3274{ 3275 if (cfq_cfqq_sync(cfqq)) { 3276 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); 3277 __cfq_update_io_thinktime(&cfqq->service_tree->ttime, 3278 cfqd->cfq_slice_idle); 3279 } 3280#ifdef CONFIG_CFQ_GROUP_IOSCHED 3281 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); 3282#endif 3283} 3284 3285static void 3286cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3287 struct request *rq) 3288{ 3289 sector_t sdist = 0; 3290 sector_t n_sec = blk_rq_sectors(rq); 3291 if (cfqq->last_request_pos) { 3292 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3293 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3294 else 3295 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3296 } 3297 3298 cfqq->seek_history <<= 1; 3299 if (blk_queue_nonrot(cfqd->queue)) 3300 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3301 else 3302 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3303} 3304 3305/* 3306 * Disable idle window if the process thinks too long or seeks so much that 3307 * it doesn't matter 3308 */ 3309static void 3310cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3311 struct cfq_io_cq *cic) 3312{ 3313 int old_idle, enable_idle; 3314 3315 /* 3316 * Don't idle for async or idle io prio class 3317 */ 3318 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3319 return; 3320 3321 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3322 3323 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3324 cfq_mark_cfqq_deep(cfqq); 3325 3326 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3327 enable_idle = 0; 3328 else if (!atomic_read(&cic->icq.ioc->active_ref) || 3329 !cfqd->cfq_slice_idle || 3330 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3331 enable_idle = 0; 3332 else if (sample_valid(cic->ttime.ttime_samples)) { 3333 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) 3334 enable_idle = 0; 3335 else 3336 enable_idle = 1; 3337 } 3338 3339 if (old_idle != enable_idle) { 3340 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3341 if (enable_idle) 3342 cfq_mark_cfqq_idle_window(cfqq); 3343 else 3344 cfq_clear_cfqq_idle_window(cfqq); 3345 } 3346} 3347 3348/* 3349 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3350 * no or if we aren't sure, a 1 will cause a preempt. 3351 */ 3352static bool 3353cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3354 struct request *rq) 3355{ 3356 struct cfq_queue *cfqq; 3357 3358 cfqq = cfqd->active_queue; 3359 if (!cfqq) 3360 return false; 3361 3362 if (cfq_class_idle(new_cfqq)) 3363 return false; 3364 3365 if (cfq_class_idle(cfqq)) 3366 return true; 3367 3368 /* 3369 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3370 */ 3371 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3372 return false; 3373 3374 /* 3375 * if the new request is sync, but the currently running queue is 3376 * not, let the sync request have priority. 3377 */ 3378 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3379 return true; 3380 3381 if (new_cfqq->cfqg != cfqq->cfqg) 3382 return false; 3383 3384 if (cfq_slice_used(cfqq)) 3385 return true; 3386 3387 /* Allow preemption only if we are idling on sync-noidle tree */ 3388 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3389 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3390 new_cfqq->service_tree->count == 2 && 3391 RB_EMPTY_ROOT(&cfqq->sort_list)) 3392 return true; 3393 3394 /* 3395 * So both queues are sync. Let the new request get disk time if 3396 * it's a metadata request and the current queue is doing regular IO. 3397 */ 3398 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) 3399 return true; 3400 3401 /* 3402 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3403 */ 3404 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3405 return true; 3406 3407 /* An idle queue should not be idle now for some reason */ 3408 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3409 return true; 3410 3411 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3412 return false; 3413 3414 /* 3415 * if this request is as-good as one we would expect from the 3416 * current cfqq, let it preempt 3417 */ 3418 if (cfq_rq_close(cfqd, cfqq, rq)) 3419 return true; 3420 3421 return false; 3422} 3423 3424/* 3425 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3426 * let it have half of its nominal slice. 3427 */ 3428static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3429{ 3430 enum wl_type_t old_type = cfqq_type(cfqd->active_queue); 3431 3432 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3433 cfq_slice_expired(cfqd, 1); 3434 3435 /* 3436 * workload type is changed, don't save slice, otherwise preempt 3437 * doesn't happen 3438 */ 3439 if (old_type != cfqq_type(cfqq)) 3440 cfqq->cfqg->saved_workload_slice = 0; 3441 3442 /* 3443 * Put the new queue at the front of the of the current list, 3444 * so we know that it will be selected next. 3445 */ 3446 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3447 3448 cfq_service_tree_add(cfqd, cfqq, 1); 3449 3450 cfqq->slice_end = 0; 3451 cfq_mark_cfqq_slice_new(cfqq); 3452} 3453 3454/* 3455 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3456 * something we should do about it 3457 */ 3458static void 3459cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3460 struct request *rq) 3461{ 3462 struct cfq_io_cq *cic = RQ_CIC(rq); 3463 3464 cfqd->rq_queued++; 3465 if (rq->cmd_flags & REQ_PRIO) 3466 cfqq->prio_pending++; 3467 3468 cfq_update_io_thinktime(cfqd, cfqq, cic); 3469 cfq_update_io_seektime(cfqd, cfqq, rq); 3470 cfq_update_idle_window(cfqd, cfqq, cic); 3471 3472 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3473 3474 if (cfqq == cfqd->active_queue) { 3475 /* 3476 * Remember that we saw a request from this process, but 3477 * don't start queuing just yet. Otherwise we risk seeing lots 3478 * of tiny requests, because we disrupt the normal plugging 3479 * and merging. If the request is already larger than a single 3480 * page, let it rip immediately. For that case we assume that 3481 * merging is already done. Ditto for a busy system that 3482 * has other work pending, don't risk delaying until the 3483 * idle timer unplug to continue working. 3484 */ 3485 if (cfq_cfqq_wait_request(cfqq)) { 3486 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3487 cfqd->busy_queues > 1) { 3488 cfq_del_timer(cfqd, cfqq); 3489 cfq_clear_cfqq_wait_request(cfqq); 3490 __blk_run_queue(cfqd->queue); 3491 } else { 3492 cfqg_stats_update_idle_time(cfqq->cfqg); 3493 cfq_mark_cfqq_must_dispatch(cfqq); 3494 } 3495 } 3496 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3497 /* 3498 * not the active queue - expire current slice if it is 3499 * idle and has expired it's mean thinktime or this new queue 3500 * has some old slice time left and is of higher priority or 3501 * this new queue is RT and the current one is BE 3502 */ 3503 cfq_preempt_queue(cfqd, cfqq); 3504 __blk_run_queue(cfqd->queue); 3505 } 3506} 3507 3508static void cfq_insert_request(struct request_queue *q, struct request *rq) 3509{ 3510 struct cfq_data *cfqd = q->elevator->elevator_data; 3511 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3512 3513 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3514 cfq_init_prio_data(cfqq, RQ_CIC(rq)); 3515 3516 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3517 list_add_tail(&rq->queuelist, &cfqq->fifo); 3518 cfq_add_rq_rb(rq); 3519 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group, 3520 rq->cmd_flags); 3521 cfq_rq_enqueued(cfqd, cfqq, rq); 3522} 3523 3524/* 3525 * Update hw_tag based on peak queue depth over 50 samples under 3526 * sufficient load. 3527 */ 3528static void cfq_update_hw_tag(struct cfq_data *cfqd) 3529{ 3530 struct cfq_queue *cfqq = cfqd->active_queue; 3531 3532 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3533 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3534 3535 if (cfqd->hw_tag == 1) 3536 return; 3537 3538 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3539 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3540 return; 3541 3542 /* 3543 * If active queue hasn't enough requests and can idle, cfq might not 3544 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3545 * case 3546 */ 3547 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3548 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3549 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3550 return; 3551 3552 if (cfqd->hw_tag_samples++ < 50) 3553 return; 3554 3555 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3556 cfqd->hw_tag = 1; 3557 else 3558 cfqd->hw_tag = 0; 3559} 3560 3561static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3562{ 3563 struct cfq_io_cq *cic = cfqd->active_cic; 3564 3565 /* If the queue already has requests, don't wait */ 3566 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3567 return false; 3568 3569 /* If there are other queues in the group, don't wait */ 3570 if (cfqq->cfqg->nr_cfqq > 1) 3571 return false; 3572 3573 /* the only queue in the group, but think time is big */ 3574 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) 3575 return false; 3576 3577 if (cfq_slice_used(cfqq)) 3578 return true; 3579 3580 /* if slice left is less than think time, wait busy */ 3581 if (cic && sample_valid(cic->ttime.ttime_samples) 3582 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) 3583 return true; 3584 3585 /* 3586 * If think times is less than a jiffy than ttime_mean=0 and above 3587 * will not be true. It might happen that slice has not expired yet 3588 * but will expire soon (4-5 ns) during select_queue(). To cover the 3589 * case where think time is less than a jiffy, mark the queue wait 3590 * busy if only 1 jiffy is left in the slice. 3591 */ 3592 if (cfqq->slice_end - jiffies == 1) 3593 return true; 3594 3595 return false; 3596} 3597 3598static void cfq_completed_request(struct request_queue *q, struct request *rq) 3599{ 3600 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3601 struct cfq_data *cfqd = cfqq->cfqd; 3602 const int sync = rq_is_sync(rq); 3603 unsigned long now; 3604 3605 now = jiffies; 3606 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3607 !!(rq->cmd_flags & REQ_NOIDLE)); 3608 3609 cfq_update_hw_tag(cfqd); 3610 3611 WARN_ON(!cfqd->rq_in_driver); 3612 WARN_ON(!cfqq->dispatched); 3613 cfqd->rq_in_driver--; 3614 cfqq->dispatched--; 3615 (RQ_CFQG(rq))->dispatched--; 3616 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq), 3617 rq_io_start_time_ns(rq), rq->cmd_flags); 3618 3619 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3620 3621 if (sync) { 3622 struct cfq_rb_root *service_tree; 3623 3624 RQ_CIC(rq)->ttime.last_end_request = now; 3625 3626 if (cfq_cfqq_on_rr(cfqq)) 3627 service_tree = cfqq->service_tree; 3628 else 3629 service_tree = service_tree_for(cfqq->cfqg, 3630 cfqq_prio(cfqq), cfqq_type(cfqq)); 3631 service_tree->ttime.last_end_request = now; 3632 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3633 cfqd->last_delayed_sync = now; 3634 } 3635 3636#ifdef CONFIG_CFQ_GROUP_IOSCHED 3637 cfqq->cfqg->ttime.last_end_request = now; 3638#endif 3639 3640 /* 3641 * If this is the active queue, check if it needs to be expired, 3642 * or if we want to idle in case it has no pending requests. 3643 */ 3644 if (cfqd->active_queue == cfqq) { 3645 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3646 3647 if (cfq_cfqq_slice_new(cfqq)) { 3648 cfq_set_prio_slice(cfqd, cfqq); 3649 cfq_clear_cfqq_slice_new(cfqq); 3650 } 3651 3652 /* 3653 * Should we wait for next request to come in before we expire 3654 * the queue. 3655 */ 3656 if (cfq_should_wait_busy(cfqd, cfqq)) { 3657 unsigned long extend_sl = cfqd->cfq_slice_idle; 3658 if (!cfqd->cfq_slice_idle) 3659 extend_sl = cfqd->cfq_group_idle; 3660 cfqq->slice_end = jiffies + extend_sl; 3661 cfq_mark_cfqq_wait_busy(cfqq); 3662 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3663 } 3664 3665 /* 3666 * Idling is not enabled on: 3667 * - expired queues 3668 * - idle-priority queues 3669 * - async queues 3670 * - queues with still some requests queued 3671 * - when there is a close cooperator 3672 */ 3673 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3674 cfq_slice_expired(cfqd, 1); 3675 else if (sync && cfqq_empty && 3676 !cfq_close_cooperator(cfqd, cfqq)) { 3677 cfq_arm_slice_timer(cfqd); 3678 } 3679 } 3680 3681 if (!cfqd->rq_in_driver) 3682 cfq_schedule_dispatch(cfqd); 3683} 3684 3685static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3686{ 3687 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3688 cfq_mark_cfqq_must_alloc_slice(cfqq); 3689 return ELV_MQUEUE_MUST; 3690 } 3691 3692 return ELV_MQUEUE_MAY; 3693} 3694 3695static int cfq_may_queue(struct request_queue *q, int rw) 3696{ 3697 struct cfq_data *cfqd = q->elevator->elevator_data; 3698 struct task_struct *tsk = current; 3699 struct cfq_io_cq *cic; 3700 struct cfq_queue *cfqq; 3701 3702 /* 3703 * don't force setup of a queue from here, as a call to may_queue 3704 * does not necessarily imply that a request actually will be queued. 3705 * so just lookup a possibly existing queue, or return 'may queue' 3706 * if that fails 3707 */ 3708 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3709 if (!cic) 3710 return ELV_MQUEUE_MAY; 3711 3712 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3713 if (cfqq) { 3714 cfq_init_prio_data(cfqq, cic); 3715 3716 return __cfq_may_queue(cfqq); 3717 } 3718 3719 return ELV_MQUEUE_MAY; 3720} 3721 3722/* 3723 * queue lock held here 3724 */ 3725static void cfq_put_request(struct request *rq) 3726{ 3727 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3728 3729 if (cfqq) { 3730 const int rw = rq_data_dir(rq); 3731 3732 BUG_ON(!cfqq->allocated[rw]); 3733 cfqq->allocated[rw]--; 3734 3735 /* Put down rq reference on cfqg */ 3736 cfqg_put(RQ_CFQG(rq)); 3737 rq->elv.priv[0] = NULL; 3738 rq->elv.priv[1] = NULL; 3739 3740 cfq_put_queue(cfqq); 3741 } 3742} 3743 3744static struct cfq_queue * 3745cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic, 3746 struct cfq_queue *cfqq) 3747{ 3748 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3749 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3750 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3751 cfq_put_queue(cfqq); 3752 return cic_to_cfqq(cic, 1); 3753} 3754 3755/* 3756 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3757 * was the last process referring to said cfqq. 3758 */ 3759static struct cfq_queue * 3760split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq) 3761{ 3762 if (cfqq_process_refs(cfqq) == 1) { 3763 cfqq->pid = current->pid; 3764 cfq_clear_cfqq_coop(cfqq); 3765 cfq_clear_cfqq_split_coop(cfqq); 3766 return cfqq; 3767 } 3768 3769 cic_set_cfqq(cic, NULL, 1); 3770 3771 cfq_put_cooperator(cfqq); 3772 3773 cfq_put_queue(cfqq); 3774 return NULL; 3775} 3776/* 3777 * Allocate cfq data structures associated with this request. 3778 */ 3779static int 3780cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, 3781 gfp_t gfp_mask) 3782{ 3783 struct cfq_data *cfqd = q->elevator->elevator_data; 3784 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq); 3785 const int rw = rq_data_dir(rq); 3786 const bool is_sync = rq_is_sync(rq); 3787 struct cfq_queue *cfqq; 3788 3789 might_sleep_if(gfp_mask & __GFP_WAIT); 3790 3791 spin_lock_irq(q->queue_lock); 3792 3793 check_ioprio_changed(cic, bio); 3794 check_blkcg_changed(cic, bio); 3795new_queue: 3796 cfqq = cic_to_cfqq(cic, is_sync); 3797 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3798 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask); 3799 cic_set_cfqq(cic, cfqq, is_sync); 3800 } else { 3801 /* 3802 * If the queue was seeky for too long, break it apart. 3803 */ 3804 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3805 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3806 cfqq = split_cfqq(cic, cfqq); 3807 if (!cfqq) 3808 goto new_queue; 3809 } 3810 3811 /* 3812 * Check to see if this queue is scheduled to merge with 3813 * another, closely cooperating queue. The merging of 3814 * queues happens here as it must be done in process context. 3815 * The reference on new_cfqq was taken in merge_cfqqs. 3816 */ 3817 if (cfqq->new_cfqq) 3818 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3819 } 3820 3821 cfqq->allocated[rw]++; 3822 3823 cfqq->ref++; 3824 cfqg_get(cfqq->cfqg); 3825 rq->elv.priv[0] = cfqq; 3826 rq->elv.priv[1] = cfqq->cfqg; 3827 spin_unlock_irq(q->queue_lock); 3828 return 0; 3829} 3830 3831static void cfq_kick_queue(struct work_struct *work) 3832{ 3833 struct cfq_data *cfqd = 3834 container_of(work, struct cfq_data, unplug_work); 3835 struct request_queue *q = cfqd->queue; 3836 3837 spin_lock_irq(q->queue_lock); 3838 __blk_run_queue(cfqd->queue); 3839 spin_unlock_irq(q->queue_lock); 3840} 3841 3842/* 3843 * Timer running if the active_queue is currently idling inside its time slice 3844 */ 3845static void cfq_idle_slice_timer(unsigned long data) 3846{ 3847 struct cfq_data *cfqd = (struct cfq_data *) data; 3848 struct cfq_queue *cfqq; 3849 unsigned long flags; 3850 int timed_out = 1; 3851 3852 cfq_log(cfqd, "idle timer fired"); 3853 3854 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3855 3856 cfqq = cfqd->active_queue; 3857 if (cfqq) { 3858 timed_out = 0; 3859 3860 /* 3861 * We saw a request before the queue expired, let it through 3862 */ 3863 if (cfq_cfqq_must_dispatch(cfqq)) 3864 goto out_kick; 3865 3866 /* 3867 * expired 3868 */ 3869 if (cfq_slice_used(cfqq)) 3870 goto expire; 3871 3872 /* 3873 * only expire and reinvoke request handler, if there are 3874 * other queues with pending requests 3875 */ 3876 if (!cfqd->busy_queues) 3877 goto out_cont; 3878 3879 /* 3880 * not expired and it has a request pending, let it dispatch 3881 */ 3882 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3883 goto out_kick; 3884 3885 /* 3886 * Queue depth flag is reset only when the idle didn't succeed 3887 */ 3888 cfq_clear_cfqq_deep(cfqq); 3889 } 3890expire: 3891 cfq_slice_expired(cfqd, timed_out); 3892out_kick: 3893 cfq_schedule_dispatch(cfqd); 3894out_cont: 3895 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3896} 3897 3898static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3899{ 3900 del_timer_sync(&cfqd->idle_slice_timer); 3901 cancel_work_sync(&cfqd->unplug_work); 3902} 3903 3904static void cfq_put_async_queues(struct cfq_data *cfqd) 3905{ 3906 int i; 3907 3908 for (i = 0; i < IOPRIO_BE_NR; i++) { 3909 if (cfqd->async_cfqq[0][i]) 3910 cfq_put_queue(cfqd->async_cfqq[0][i]); 3911 if (cfqd->async_cfqq[1][i]) 3912 cfq_put_queue(cfqd->async_cfqq[1][i]); 3913 } 3914 3915 if (cfqd->async_idle_cfqq) 3916 cfq_put_queue(cfqd->async_idle_cfqq); 3917} 3918 3919static void cfq_exit_queue(struct elevator_queue *e) 3920{ 3921 struct cfq_data *cfqd = e->elevator_data; 3922 struct request_queue *q = cfqd->queue; 3923 3924 cfq_shutdown_timer_wq(cfqd); 3925 3926 spin_lock_irq(q->queue_lock); 3927 3928 if (cfqd->active_queue) 3929 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3930 3931 cfq_put_async_queues(cfqd); 3932 3933 spin_unlock_irq(q->queue_lock); 3934 3935 cfq_shutdown_timer_wq(cfqd); 3936 3937#ifndef CONFIG_CFQ_GROUP_IOSCHED 3938 kfree(cfqd->root_group); 3939#endif 3940 blkcg_deactivate_policy(q, &blkio_policy_cfq); 3941 kfree(cfqd); 3942} 3943 3944static int cfq_init_queue(struct request_queue *q) 3945{ 3946 struct cfq_data *cfqd; 3947 struct blkio_group *blkg __maybe_unused; 3948 int i, ret; 3949 3950 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3951 if (!cfqd) 3952 return -ENOMEM; 3953 3954 cfqd->queue = q; 3955 q->elevator->elevator_data = cfqd; 3956 3957 /* Init root service tree */ 3958 cfqd->grp_service_tree = CFQ_RB_ROOT; 3959 3960 /* Init root group and prefer root group over other groups by default */ 3961#ifdef CONFIG_CFQ_GROUP_IOSCHED 3962 ret = blkcg_activate_policy(q, &blkio_policy_cfq); 3963 if (ret) 3964 goto out_free; 3965 3966 cfqd->root_group = blkg_to_cfqg(q->root_blkg); 3967#else 3968 ret = -ENOMEM; 3969 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group), 3970 GFP_KERNEL, cfqd->queue->node); 3971 if (!cfqd->root_group) 3972 goto out_free; 3973 3974 cfq_init_cfqg_base(cfqd->root_group); 3975#endif 3976 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT; 3977 3978 /* 3979 * Not strictly needed (since RB_ROOT just clears the node and we 3980 * zeroed cfqd on alloc), but better be safe in case someone decides 3981 * to add magic to the rb code 3982 */ 3983 for (i = 0; i < CFQ_PRIO_LISTS; i++) 3984 cfqd->prio_trees[i] = RB_ROOT; 3985 3986 /* 3987 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 3988 * Grab a permanent reference to it, so that the normal code flow 3989 * will not attempt to free it. oom_cfqq is linked to root_group 3990 * but shouldn't hold a reference as it'll never be unlinked. Lose 3991 * the reference from linking right away. 3992 */ 3993 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 3994 cfqd->oom_cfqq.ref++; 3995 3996 spin_lock_irq(q->queue_lock); 3997 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group); 3998 cfqg_put(cfqd->root_group); 3999 spin_unlock_irq(q->queue_lock); 4000 4001 init_timer(&cfqd->idle_slice_timer); 4002 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4003 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4004 4005 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4006 4007 cfqd->cfq_quantum = cfq_quantum; 4008 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4009 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4010 cfqd->cfq_back_max = cfq_back_max; 4011 cfqd->cfq_back_penalty = cfq_back_penalty; 4012 cfqd->cfq_slice[0] = cfq_slice_async; 4013 cfqd->cfq_slice[1] = cfq_slice_sync; 4014 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4015 cfqd->cfq_slice_idle = cfq_slice_idle; 4016 cfqd->cfq_group_idle = cfq_group_idle; 4017 cfqd->cfq_latency = 1; 4018 cfqd->hw_tag = -1; 4019 /* 4020 * we optimistically start assuming sync ops weren't delayed in last 4021 * second, in order to have larger depth for async operations. 4022 */ 4023 cfqd->last_delayed_sync = jiffies - HZ; 4024 return 0; 4025 4026out_free: 4027 kfree(cfqd); 4028 return ret; 4029} 4030 4031/* 4032 * sysfs parts below --> 4033 */ 4034static ssize_t 4035cfq_var_show(unsigned int var, char *page) 4036{ 4037 return sprintf(page, "%d\n", var); 4038} 4039 4040static ssize_t 4041cfq_var_store(unsigned int *var, const char *page, size_t count) 4042{ 4043 char *p = (char *) page; 4044 4045 *var = simple_strtoul(p, &p, 10); 4046 return count; 4047} 4048 4049#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4050static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4051{ \ 4052 struct cfq_data *cfqd = e->elevator_data; \ 4053 unsigned int __data = __VAR; \ 4054 if (__CONV) \ 4055 __data = jiffies_to_msecs(__data); \ 4056 return cfq_var_show(__data, (page)); \ 4057} 4058SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4059SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4060SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4061SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4062SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4063SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4064SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4065SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4066SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4067SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4068SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4069#undef SHOW_FUNCTION 4070 4071#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4072static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4073{ \ 4074 struct cfq_data *cfqd = e->elevator_data; \ 4075 unsigned int __data; \ 4076 int ret = cfq_var_store(&__data, (page), count); \ 4077 if (__data < (MIN)) \ 4078 __data = (MIN); \ 4079 else if (__data > (MAX)) \ 4080 __data = (MAX); \ 4081 if (__CONV) \ 4082 *(__PTR) = msecs_to_jiffies(__data); \ 4083 else \ 4084 *(__PTR) = __data; \ 4085 return ret; \ 4086} 4087STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4088STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4089 UINT_MAX, 1); 4090STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4091 UINT_MAX, 1); 4092STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4093STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4094 UINT_MAX, 0); 4095STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4096STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4097STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4098STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4099STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4100 UINT_MAX, 0); 4101STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4102#undef STORE_FUNCTION 4103 4104#define CFQ_ATTR(name) \ 4105 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4106 4107static struct elv_fs_entry cfq_attrs[] = { 4108 CFQ_ATTR(quantum), 4109 CFQ_ATTR(fifo_expire_sync), 4110 CFQ_ATTR(fifo_expire_async), 4111 CFQ_ATTR(back_seek_max), 4112 CFQ_ATTR(back_seek_penalty), 4113 CFQ_ATTR(slice_sync), 4114 CFQ_ATTR(slice_async), 4115 CFQ_ATTR(slice_async_rq), 4116 CFQ_ATTR(slice_idle), 4117 CFQ_ATTR(group_idle), 4118 CFQ_ATTR(low_latency), 4119 __ATTR_NULL 4120}; 4121 4122static struct elevator_type iosched_cfq = { 4123 .ops = { 4124 .elevator_merge_fn = cfq_merge, 4125 .elevator_merged_fn = cfq_merged_request, 4126 .elevator_merge_req_fn = cfq_merged_requests, 4127 .elevator_allow_merge_fn = cfq_allow_merge, 4128 .elevator_bio_merged_fn = cfq_bio_merged, 4129 .elevator_dispatch_fn = cfq_dispatch_requests, 4130 .elevator_add_req_fn = cfq_insert_request, 4131 .elevator_activate_req_fn = cfq_activate_request, 4132 .elevator_deactivate_req_fn = cfq_deactivate_request, 4133 .elevator_completed_req_fn = cfq_completed_request, 4134 .elevator_former_req_fn = elv_rb_former_request, 4135 .elevator_latter_req_fn = elv_rb_latter_request, 4136 .elevator_init_icq_fn = cfq_init_icq, 4137 .elevator_exit_icq_fn = cfq_exit_icq, 4138 .elevator_set_req_fn = cfq_set_request, 4139 .elevator_put_req_fn = cfq_put_request, 4140 .elevator_may_queue_fn = cfq_may_queue, 4141 .elevator_init_fn = cfq_init_queue, 4142 .elevator_exit_fn = cfq_exit_queue, 4143 }, 4144 .icq_size = sizeof(struct cfq_io_cq), 4145 .icq_align = __alignof__(struct cfq_io_cq), 4146 .elevator_attrs = cfq_attrs, 4147 .elevator_name = "cfq", 4148 .elevator_owner = THIS_MODULE, 4149}; 4150 4151#ifdef CONFIG_CFQ_GROUP_IOSCHED 4152static struct blkio_policy_type blkio_policy_cfq = { 4153 .ops = { 4154 .blkio_init_group_fn = cfq_init_blkio_group, 4155 .blkio_reset_group_stats_fn = cfqg_stats_reset, 4156 }, 4157 .pdata_size = sizeof(struct cfq_group), 4158 .cftypes = cfq_blkcg_files, 4159}; 4160#endif 4161 4162static int __init cfq_init(void) 4163{ 4164 int ret; 4165 4166 /* 4167 * could be 0 on HZ < 1000 setups 4168 */ 4169 if (!cfq_slice_async) 4170 cfq_slice_async = 1; 4171 if (!cfq_slice_idle) 4172 cfq_slice_idle = 1; 4173 4174#ifdef CONFIG_CFQ_GROUP_IOSCHED 4175 if (!cfq_group_idle) 4176 cfq_group_idle = 1; 4177#else 4178 cfq_group_idle = 0; 4179#endif 4180 4181 ret = blkio_policy_register(&blkio_policy_cfq); 4182 if (ret) 4183 return ret; 4184 4185 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4186 if (!cfq_pool) 4187 goto err_pol_unreg; 4188 4189 ret = elv_register(&iosched_cfq); 4190 if (ret) 4191 goto err_free_pool; 4192 4193 return 0; 4194 4195err_free_pool: 4196 kmem_cache_destroy(cfq_pool); 4197err_pol_unreg: 4198 blkio_policy_unregister(&blkio_policy_cfq); 4199 return ret; 4200} 4201 4202static void __exit cfq_exit(void) 4203{ 4204 blkio_policy_unregister(&blkio_policy_cfq); 4205 elv_unregister(&iosched_cfq); 4206 kmem_cache_destroy(cfq_pool); 4207} 4208 4209module_init(cfq_init); 4210module_exit(cfq_exit); 4211 4212MODULE_AUTHOR("Jens Axboe"); 4213MODULE_LICENSE("GPL"); 4214MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4215