cfq-iosched.c revision 6d816ec7c83871da7c2472af7479d2438e641052
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 20/* 21 * tunables 22 */ 23/* max queue in one round of service */ 24static const int cfq_quantum = 8; 25static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 26/* maximum backwards seek, in KiB */ 27static const int cfq_back_max = 16 * 1024; 28/* penalty of a backwards seek */ 29static const int cfq_back_penalty = 2; 30static const int cfq_slice_sync = HZ / 10; 31static int cfq_slice_async = HZ / 25; 32static const int cfq_slice_async_rq = 2; 33static int cfq_slice_idle = HZ / 125; 34static int cfq_group_idle = HZ / 125; 35static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 36static const int cfq_hist_divisor = 4; 37 38/* 39 * offset from end of service tree 40 */ 41#define CFQ_IDLE_DELAY (HZ / 5) 42 43/* 44 * below this threshold, we consider thinktime immediate 45 */ 46#define CFQ_MIN_TT (2) 47 48#define CFQ_SLICE_SCALE (5) 49#define CFQ_HW_QUEUE_MIN (5) 50#define CFQ_SERVICE_SHIFT 12 51 52#define CFQQ_SEEK_THR (sector_t)(8 * 100) 53#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 54#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 55#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 56 57#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq) 58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0]) 59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1]) 60 61static struct kmem_cache *cfq_pool; 62 63#define CFQ_PRIO_LISTS IOPRIO_BE_NR 64#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 65#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 66 67#define sample_valid(samples) ((samples) > 80) 68#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 69 70struct cfq_ttime { 71 unsigned long last_end_request; 72 73 unsigned long ttime_total; 74 unsigned long ttime_samples; 75 unsigned long ttime_mean; 76}; 77 78/* 79 * Most of our rbtree usage is for sorting with min extraction, so 80 * if we cache the leftmost node we don't have to walk down the tree 81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 82 * move this into the elevator for the rq sorting as well. 83 */ 84struct cfq_rb_root { 85 struct rb_root rb; 86 struct rb_node *left; 87 unsigned count; 88 unsigned total_weight; 89 u64 min_vdisktime; 90 struct cfq_ttime ttime; 91}; 92#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \ 93 .ttime = {.last_end_request = jiffies,},} 94 95/* 96 * Per process-grouping structure 97 */ 98struct cfq_queue { 99 /* reference count */ 100 int ref; 101 /* various state flags, see below */ 102 unsigned int flags; 103 /* parent cfq_data */ 104 struct cfq_data *cfqd; 105 /* service_tree member */ 106 struct rb_node rb_node; 107 /* service_tree key */ 108 unsigned long rb_key; 109 /* prio tree member */ 110 struct rb_node p_node; 111 /* prio tree root we belong to, if any */ 112 struct rb_root *p_root; 113 /* sorted list of pending requests */ 114 struct rb_root sort_list; 115 /* if fifo isn't expired, next request to serve */ 116 struct request *next_rq; 117 /* requests queued in sort_list */ 118 int queued[2]; 119 /* currently allocated requests */ 120 int allocated[2]; 121 /* fifo list of requests in sort_list */ 122 struct list_head fifo; 123 124 /* time when queue got scheduled in to dispatch first request. */ 125 unsigned long dispatch_start; 126 unsigned int allocated_slice; 127 unsigned int slice_dispatch; 128 /* time when first request from queue completed and slice started. */ 129 unsigned long slice_start; 130 unsigned long slice_end; 131 long slice_resid; 132 133 /* pending priority requests */ 134 int prio_pending; 135 /* number of requests that are on the dispatch list or inside driver */ 136 int dispatched; 137 138 /* io prio of this group */ 139 unsigned short ioprio, org_ioprio; 140 unsigned short ioprio_class; 141 142 pid_t pid; 143 144 u32 seek_history; 145 sector_t last_request_pos; 146 147 struct cfq_rb_root *service_tree; 148 struct cfq_queue *new_cfqq; 149 struct cfq_group *cfqg; 150 /* Number of sectors dispatched from queue in single dispatch round */ 151 unsigned long nr_sectors; 152}; 153 154/* 155 * First index in the service_trees. 156 * IDLE is handled separately, so it has negative index 157 */ 158enum wl_class_t { 159 BE_WORKLOAD = 0, 160 RT_WORKLOAD = 1, 161 IDLE_WORKLOAD = 2, 162 CFQ_PRIO_NR, 163}; 164 165/* 166 * Second index in the service_trees. 167 */ 168enum wl_type_t { 169 ASYNC_WORKLOAD = 0, 170 SYNC_NOIDLE_WORKLOAD = 1, 171 SYNC_WORKLOAD = 2 172}; 173 174struct cfqg_stats { 175#ifdef CONFIG_CFQ_GROUP_IOSCHED 176 /* total bytes transferred */ 177 struct blkg_rwstat service_bytes; 178 /* total IOs serviced, post merge */ 179 struct blkg_rwstat serviced; 180 /* number of ios merged */ 181 struct blkg_rwstat merged; 182 /* total time spent on device in ns, may not be accurate w/ queueing */ 183 struct blkg_rwstat service_time; 184 /* total time spent waiting in scheduler queue in ns */ 185 struct blkg_rwstat wait_time; 186 /* number of IOs queued up */ 187 struct blkg_rwstat queued; 188 /* total sectors transferred */ 189 struct blkg_stat sectors; 190 /* total disk time and nr sectors dispatched by this group */ 191 struct blkg_stat time; 192#ifdef CONFIG_DEBUG_BLK_CGROUP 193 /* time not charged to this cgroup */ 194 struct blkg_stat unaccounted_time; 195 /* sum of number of ios queued across all samples */ 196 struct blkg_stat avg_queue_size_sum; 197 /* count of samples taken for average */ 198 struct blkg_stat avg_queue_size_samples; 199 /* how many times this group has been removed from service tree */ 200 struct blkg_stat dequeue; 201 /* total time spent waiting for it to be assigned a timeslice. */ 202 struct blkg_stat group_wait_time; 203 /* time spent idling for this blkcg_gq */ 204 struct blkg_stat idle_time; 205 /* total time with empty current active q with other requests queued */ 206 struct blkg_stat empty_time; 207 /* fields after this shouldn't be cleared on stat reset */ 208 uint64_t start_group_wait_time; 209 uint64_t start_idle_time; 210 uint64_t start_empty_time; 211 uint16_t flags; 212#endif /* CONFIG_DEBUG_BLK_CGROUP */ 213#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 214}; 215 216/* This is per cgroup per device grouping structure */ 217struct cfq_group { 218 /* must be the first member */ 219 struct blkg_policy_data pd; 220 221 /* group service_tree member */ 222 struct rb_node rb_node; 223 224 /* group service_tree key */ 225 u64 vdisktime; 226 unsigned int weight; 227 unsigned int new_weight; 228 unsigned int dev_weight; 229 230 /* number of cfqq currently on this group */ 231 int nr_cfqq; 232 233 /* 234 * Per group busy queues average. Useful for workload slice calc. We 235 * create the array for each prio class but at run time it is used 236 * only for RT and BE class and slot for IDLE class remains unused. 237 * This is primarily done to avoid confusion and a gcc warning. 238 */ 239 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 240 /* 241 * rr lists of queues with requests. We maintain service trees for 242 * RT and BE classes. These trees are subdivided in subclasses 243 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 244 * class there is no subclassification and all the cfq queues go on 245 * a single tree service_tree_idle. 246 * Counts are embedded in the cfq_rb_root 247 */ 248 struct cfq_rb_root service_trees[2][3]; 249 struct cfq_rb_root service_tree_idle; 250 251 unsigned long saved_wl_slice; 252 enum wl_type_t saved_wl_type; 253 enum wl_class_t saved_wl_class; 254 255 /* number of requests that are on the dispatch list or inside driver */ 256 int dispatched; 257 struct cfq_ttime ttime; 258 struct cfqg_stats stats; 259}; 260 261struct cfq_io_cq { 262 struct io_cq icq; /* must be the first member */ 263 struct cfq_queue *cfqq[2]; 264 struct cfq_ttime ttime; 265 int ioprio; /* the current ioprio */ 266#ifdef CONFIG_CFQ_GROUP_IOSCHED 267 uint64_t blkcg_id; /* the current blkcg ID */ 268#endif 269}; 270 271/* 272 * Per block device queue structure 273 */ 274struct cfq_data { 275 struct request_queue *queue; 276 /* Root service tree for cfq_groups */ 277 struct cfq_rb_root grp_service_tree; 278 struct cfq_group *root_group; 279 280 /* 281 * The priority currently being served 282 */ 283 enum wl_class_t serving_wl_class; 284 enum wl_type_t serving_wl_type; 285 unsigned long workload_expires; 286 struct cfq_group *serving_group; 287 288 /* 289 * Each priority tree is sorted by next_request position. These 290 * trees are used when determining if two or more queues are 291 * interleaving requests (see cfq_close_cooperator). 292 */ 293 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 294 295 unsigned int busy_queues; 296 unsigned int busy_sync_queues; 297 298 int rq_in_driver; 299 int rq_in_flight[2]; 300 301 /* 302 * queue-depth detection 303 */ 304 int rq_queued; 305 int hw_tag; 306 /* 307 * hw_tag can be 308 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 309 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 310 * 0 => no NCQ 311 */ 312 int hw_tag_est_depth; 313 unsigned int hw_tag_samples; 314 315 /* 316 * idle window management 317 */ 318 struct timer_list idle_slice_timer; 319 struct work_struct unplug_work; 320 321 struct cfq_queue *active_queue; 322 struct cfq_io_cq *active_cic; 323 324 /* 325 * async queue for each priority case 326 */ 327 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 328 struct cfq_queue *async_idle_cfqq; 329 330 sector_t last_position; 331 332 /* 333 * tunables, see top of file 334 */ 335 unsigned int cfq_quantum; 336 unsigned int cfq_fifo_expire[2]; 337 unsigned int cfq_back_penalty; 338 unsigned int cfq_back_max; 339 unsigned int cfq_slice[2]; 340 unsigned int cfq_slice_async_rq; 341 unsigned int cfq_slice_idle; 342 unsigned int cfq_group_idle; 343 unsigned int cfq_latency; 344 unsigned int cfq_target_latency; 345 346 /* 347 * Fallback dummy cfqq for extreme OOM conditions 348 */ 349 struct cfq_queue oom_cfqq; 350 351 unsigned long last_delayed_sync; 352}; 353 354static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 355 356static struct cfq_rb_root *st_for(struct cfq_group *cfqg, 357 enum wl_class_t class, 358 enum wl_type_t type) 359{ 360 if (!cfqg) 361 return NULL; 362 363 if (class == IDLE_WORKLOAD) 364 return &cfqg->service_tree_idle; 365 366 return &cfqg->service_trees[class][type]; 367} 368 369enum cfqq_state_flags { 370 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 371 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 372 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 373 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 374 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 375 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 376 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 377 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 378 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 379 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 380 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 381 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 382 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 383}; 384 385#define CFQ_CFQQ_FNS(name) \ 386static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 387{ \ 388 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 389} \ 390static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 391{ \ 392 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 393} \ 394static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 395{ \ 396 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 397} 398 399CFQ_CFQQ_FNS(on_rr); 400CFQ_CFQQ_FNS(wait_request); 401CFQ_CFQQ_FNS(must_dispatch); 402CFQ_CFQQ_FNS(must_alloc_slice); 403CFQ_CFQQ_FNS(fifo_expire); 404CFQ_CFQQ_FNS(idle_window); 405CFQ_CFQQ_FNS(prio_changed); 406CFQ_CFQQ_FNS(slice_new); 407CFQ_CFQQ_FNS(sync); 408CFQ_CFQQ_FNS(coop); 409CFQ_CFQQ_FNS(split_coop); 410CFQ_CFQQ_FNS(deep); 411CFQ_CFQQ_FNS(wait_busy); 412#undef CFQ_CFQQ_FNS 413 414static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd) 415{ 416 return pd ? container_of(pd, struct cfq_group, pd) : NULL; 417} 418 419static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg) 420{ 421 return pd_to_blkg(&cfqg->pd); 422} 423 424#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP) 425 426/* cfqg stats flags */ 427enum cfqg_stats_flags { 428 CFQG_stats_waiting = 0, 429 CFQG_stats_idling, 430 CFQG_stats_empty, 431}; 432 433#define CFQG_FLAG_FNS(name) \ 434static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \ 435{ \ 436 stats->flags |= (1 << CFQG_stats_##name); \ 437} \ 438static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \ 439{ \ 440 stats->flags &= ~(1 << CFQG_stats_##name); \ 441} \ 442static inline int cfqg_stats_##name(struct cfqg_stats *stats) \ 443{ \ 444 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \ 445} \ 446 447CFQG_FLAG_FNS(waiting) 448CFQG_FLAG_FNS(idling) 449CFQG_FLAG_FNS(empty) 450#undef CFQG_FLAG_FNS 451 452/* This should be called with the queue_lock held. */ 453static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats) 454{ 455 unsigned long long now; 456 457 if (!cfqg_stats_waiting(stats)) 458 return; 459 460 now = sched_clock(); 461 if (time_after64(now, stats->start_group_wait_time)) 462 blkg_stat_add(&stats->group_wait_time, 463 now - stats->start_group_wait_time); 464 cfqg_stats_clear_waiting(stats); 465} 466 467/* This should be called with the queue_lock held. */ 468static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, 469 struct cfq_group *curr_cfqg) 470{ 471 struct cfqg_stats *stats = &cfqg->stats; 472 473 if (cfqg_stats_waiting(stats)) 474 return; 475 if (cfqg == curr_cfqg) 476 return; 477 stats->start_group_wait_time = sched_clock(); 478 cfqg_stats_mark_waiting(stats); 479} 480 481/* This should be called with the queue_lock held. */ 482static void cfqg_stats_end_empty_time(struct cfqg_stats *stats) 483{ 484 unsigned long long now; 485 486 if (!cfqg_stats_empty(stats)) 487 return; 488 489 now = sched_clock(); 490 if (time_after64(now, stats->start_empty_time)) 491 blkg_stat_add(&stats->empty_time, 492 now - stats->start_empty_time); 493 cfqg_stats_clear_empty(stats); 494} 495 496static void cfqg_stats_update_dequeue(struct cfq_group *cfqg) 497{ 498 blkg_stat_add(&cfqg->stats.dequeue, 1); 499} 500 501static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) 502{ 503 struct cfqg_stats *stats = &cfqg->stats; 504 505 if (blkg_rwstat_sum(&stats->queued)) 506 return; 507 508 /* 509 * group is already marked empty. This can happen if cfqq got new 510 * request in parent group and moved to this group while being added 511 * to service tree. Just ignore the event and move on. 512 */ 513 if (cfqg_stats_empty(stats)) 514 return; 515 516 stats->start_empty_time = sched_clock(); 517 cfqg_stats_mark_empty(stats); 518} 519 520static void cfqg_stats_update_idle_time(struct cfq_group *cfqg) 521{ 522 struct cfqg_stats *stats = &cfqg->stats; 523 524 if (cfqg_stats_idling(stats)) { 525 unsigned long long now = sched_clock(); 526 527 if (time_after64(now, stats->start_idle_time)) 528 blkg_stat_add(&stats->idle_time, 529 now - stats->start_idle_time); 530 cfqg_stats_clear_idling(stats); 531 } 532} 533 534static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) 535{ 536 struct cfqg_stats *stats = &cfqg->stats; 537 538 BUG_ON(cfqg_stats_idling(stats)); 539 540 stats->start_idle_time = sched_clock(); 541 cfqg_stats_mark_idling(stats); 542} 543 544static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) 545{ 546 struct cfqg_stats *stats = &cfqg->stats; 547 548 blkg_stat_add(&stats->avg_queue_size_sum, 549 blkg_rwstat_sum(&stats->queued)); 550 blkg_stat_add(&stats->avg_queue_size_samples, 1); 551 cfqg_stats_update_group_wait_time(stats); 552} 553 554#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 555 556static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { } 557static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { } 558static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { } 559static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { } 560static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { } 561static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { } 562static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { } 563 564#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 565 566#ifdef CONFIG_CFQ_GROUP_IOSCHED 567 568static struct blkcg_policy blkcg_policy_cfq; 569 570static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg) 571{ 572 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq)); 573} 574 575static inline void cfqg_get(struct cfq_group *cfqg) 576{ 577 return blkg_get(cfqg_to_blkg(cfqg)); 578} 579 580static inline void cfqg_put(struct cfq_group *cfqg) 581{ 582 return blkg_put(cfqg_to_blkg(cfqg)); 583} 584 585#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \ 586 char __pbuf[128]; \ 587 \ 588 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \ 589 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 590 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 591 __pbuf, ##args); \ 592} while (0) 593 594#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \ 595 char __pbuf[128]; \ 596 \ 597 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \ 598 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \ 599} while (0) 600 601static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 602 struct cfq_group *curr_cfqg, int rw) 603{ 604 blkg_rwstat_add(&cfqg->stats.queued, rw, 1); 605 cfqg_stats_end_empty_time(&cfqg->stats); 606 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg); 607} 608 609static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 610 unsigned long time, unsigned long unaccounted_time) 611{ 612 blkg_stat_add(&cfqg->stats.time, time); 613#ifdef CONFIG_DEBUG_BLK_CGROUP 614 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time); 615#endif 616} 617 618static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) 619{ 620 blkg_rwstat_add(&cfqg->stats.queued, rw, -1); 621} 622 623static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) 624{ 625 blkg_rwstat_add(&cfqg->stats.merged, rw, 1); 626} 627 628static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 629 uint64_t bytes, int rw) 630{ 631 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9); 632 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1); 633 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes); 634} 635 636static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 637 uint64_t start_time, uint64_t io_start_time, int rw) 638{ 639 struct cfqg_stats *stats = &cfqg->stats; 640 unsigned long long now = sched_clock(); 641 642 if (time_after64(now, io_start_time)) 643 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time); 644 if (time_after64(io_start_time, start_time)) 645 blkg_rwstat_add(&stats->wait_time, rw, 646 io_start_time - start_time); 647} 648 649static void cfq_pd_reset_stats(struct blkcg_gq *blkg) 650{ 651 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 652 struct cfqg_stats *stats = &cfqg->stats; 653 654 /* queued stats shouldn't be cleared */ 655 blkg_rwstat_reset(&stats->service_bytes); 656 blkg_rwstat_reset(&stats->serviced); 657 blkg_rwstat_reset(&stats->merged); 658 blkg_rwstat_reset(&stats->service_time); 659 blkg_rwstat_reset(&stats->wait_time); 660 blkg_stat_reset(&stats->time); 661#ifdef CONFIG_DEBUG_BLK_CGROUP 662 blkg_stat_reset(&stats->unaccounted_time); 663 blkg_stat_reset(&stats->avg_queue_size_sum); 664 blkg_stat_reset(&stats->avg_queue_size_samples); 665 blkg_stat_reset(&stats->dequeue); 666 blkg_stat_reset(&stats->group_wait_time); 667 blkg_stat_reset(&stats->idle_time); 668 blkg_stat_reset(&stats->empty_time); 669#endif 670} 671 672#else /* CONFIG_CFQ_GROUP_IOSCHED */ 673 674static inline void cfqg_get(struct cfq_group *cfqg) { } 675static inline void cfqg_put(struct cfq_group *cfqg) { } 676 677#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 678 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 679#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 680 681static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 682 struct cfq_group *curr_cfqg, int rw) { } 683static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 684 unsigned long time, unsigned long unaccounted_time) { } 685static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { } 686static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { } 687static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 688 uint64_t bytes, int rw) { } 689static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 690 uint64_t start_time, uint64_t io_start_time, int rw) { } 691 692#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 693 694#define cfq_log(cfqd, fmt, args...) \ 695 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 696 697/* Traverses through cfq group service trees */ 698#define for_each_cfqg_st(cfqg, i, j, st) \ 699 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 700 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 701 : &cfqg->service_tree_idle; \ 702 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 703 (i == IDLE_WORKLOAD && j == 0); \ 704 j++, st = i < IDLE_WORKLOAD ? \ 705 &cfqg->service_trees[i][j]: NULL) \ 706 707static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, 708 struct cfq_ttime *ttime, bool group_idle) 709{ 710 unsigned long slice; 711 if (!sample_valid(ttime->ttime_samples)) 712 return false; 713 if (group_idle) 714 slice = cfqd->cfq_group_idle; 715 else 716 slice = cfqd->cfq_slice_idle; 717 return ttime->ttime_mean > slice; 718} 719 720static inline bool iops_mode(struct cfq_data *cfqd) 721{ 722 /* 723 * If we are not idling on queues and it is a NCQ drive, parallel 724 * execution of requests is on and measuring time is not possible 725 * in most of the cases until and unless we drive shallower queue 726 * depths and that becomes a performance bottleneck. In such cases 727 * switch to start providing fairness in terms of number of IOs. 728 */ 729 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 730 return true; 731 else 732 return false; 733} 734 735static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq) 736{ 737 if (cfq_class_idle(cfqq)) 738 return IDLE_WORKLOAD; 739 if (cfq_class_rt(cfqq)) 740 return RT_WORKLOAD; 741 return BE_WORKLOAD; 742} 743 744 745static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 746{ 747 if (!cfq_cfqq_sync(cfqq)) 748 return ASYNC_WORKLOAD; 749 if (!cfq_cfqq_idle_window(cfqq)) 750 return SYNC_NOIDLE_WORKLOAD; 751 return SYNC_WORKLOAD; 752} 753 754static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class, 755 struct cfq_data *cfqd, 756 struct cfq_group *cfqg) 757{ 758 if (wl_class == IDLE_WORKLOAD) 759 return cfqg->service_tree_idle.count; 760 761 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count + 762 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count + 763 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count; 764} 765 766static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 767 struct cfq_group *cfqg) 768{ 769 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count + 770 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 771} 772 773static void cfq_dispatch_insert(struct request_queue *, struct request *); 774static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync, 775 struct cfq_io_cq *cic, struct bio *bio, 776 gfp_t gfp_mask); 777 778static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq) 779{ 780 /* cic->icq is the first member, %NULL will convert to %NULL */ 781 return container_of(icq, struct cfq_io_cq, icq); 782} 783 784static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd, 785 struct io_context *ioc) 786{ 787 if (ioc) 788 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue)); 789 return NULL; 790} 791 792static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync) 793{ 794 return cic->cfqq[is_sync]; 795} 796 797static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq, 798 bool is_sync) 799{ 800 cic->cfqq[is_sync] = cfqq; 801} 802 803static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic) 804{ 805 return cic->icq.q->elevator->elevator_data; 806} 807 808/* 809 * We regard a request as SYNC, if it's either a read or has the SYNC bit 810 * set (in which case it could also be direct WRITE). 811 */ 812static inline bool cfq_bio_sync(struct bio *bio) 813{ 814 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 815} 816 817/* 818 * scheduler run of queue, if there are requests pending and no one in the 819 * driver that will restart queueing 820 */ 821static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 822{ 823 if (cfqd->busy_queues) { 824 cfq_log(cfqd, "schedule dispatch"); 825 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 826 } 827} 828 829/* 830 * Scale schedule slice based on io priority. Use the sync time slice only 831 * if a queue is marked sync and has sync io queued. A sync queue with async 832 * io only, should not get full sync slice length. 833 */ 834static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 835 unsigned short prio) 836{ 837 const int base_slice = cfqd->cfq_slice[sync]; 838 839 WARN_ON(prio >= IOPRIO_BE_NR); 840 841 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 842} 843 844static inline int 845cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 846{ 847 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 848} 849 850static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 851{ 852 u64 d = delta << CFQ_SERVICE_SHIFT; 853 854 d = d * CFQ_WEIGHT_DEFAULT; 855 do_div(d, cfqg->weight); 856 return d; 857} 858 859static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 860{ 861 s64 delta = (s64)(vdisktime - min_vdisktime); 862 if (delta > 0) 863 min_vdisktime = vdisktime; 864 865 return min_vdisktime; 866} 867 868static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 869{ 870 s64 delta = (s64)(vdisktime - min_vdisktime); 871 if (delta < 0) 872 min_vdisktime = vdisktime; 873 874 return min_vdisktime; 875} 876 877static void update_min_vdisktime(struct cfq_rb_root *st) 878{ 879 struct cfq_group *cfqg; 880 881 if (st->left) { 882 cfqg = rb_entry_cfqg(st->left); 883 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 884 cfqg->vdisktime); 885 } 886} 887 888/* 889 * get averaged number of queues of RT/BE priority. 890 * average is updated, with a formula that gives more weight to higher numbers, 891 * to quickly follows sudden increases and decrease slowly 892 */ 893 894static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 895 struct cfq_group *cfqg, bool rt) 896{ 897 unsigned min_q, max_q; 898 unsigned mult = cfq_hist_divisor - 1; 899 unsigned round = cfq_hist_divisor / 2; 900 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 901 902 min_q = min(cfqg->busy_queues_avg[rt], busy); 903 max_q = max(cfqg->busy_queues_avg[rt], busy); 904 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 905 cfq_hist_divisor; 906 return cfqg->busy_queues_avg[rt]; 907} 908 909static inline unsigned 910cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 911{ 912 struct cfq_rb_root *st = &cfqd->grp_service_tree; 913 914 return cfqd->cfq_target_latency * cfqg->weight / st->total_weight; 915} 916 917static inline unsigned 918cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 919{ 920 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 921 if (cfqd->cfq_latency) { 922 /* 923 * interested queues (we consider only the ones with the same 924 * priority class in the cfq group) 925 */ 926 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 927 cfq_class_rt(cfqq)); 928 unsigned sync_slice = cfqd->cfq_slice[1]; 929 unsigned expect_latency = sync_slice * iq; 930 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 931 932 if (expect_latency > group_slice) { 933 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 934 /* scale low_slice according to IO priority 935 * and sync vs async */ 936 unsigned low_slice = 937 min(slice, base_low_slice * slice / sync_slice); 938 /* the adapted slice value is scaled to fit all iqs 939 * into the target latency */ 940 slice = max(slice * group_slice / expect_latency, 941 low_slice); 942 } 943 } 944 return slice; 945} 946 947static inline void 948cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 949{ 950 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 951 952 cfqq->slice_start = jiffies; 953 cfqq->slice_end = jiffies + slice; 954 cfqq->allocated_slice = slice; 955 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 956} 957 958/* 959 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 960 * isn't valid until the first request from the dispatch is activated 961 * and the slice time set. 962 */ 963static inline bool cfq_slice_used(struct cfq_queue *cfqq) 964{ 965 if (cfq_cfqq_slice_new(cfqq)) 966 return false; 967 if (time_before(jiffies, cfqq->slice_end)) 968 return false; 969 970 return true; 971} 972 973/* 974 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 975 * We choose the request that is closest to the head right now. Distance 976 * behind the head is penalized and only allowed to a certain extent. 977 */ 978static struct request * 979cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 980{ 981 sector_t s1, s2, d1 = 0, d2 = 0; 982 unsigned long back_max; 983#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 984#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 985 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 986 987 if (rq1 == NULL || rq1 == rq2) 988 return rq2; 989 if (rq2 == NULL) 990 return rq1; 991 992 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 993 return rq_is_sync(rq1) ? rq1 : rq2; 994 995 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) 996 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; 997 998 s1 = blk_rq_pos(rq1); 999 s2 = blk_rq_pos(rq2); 1000 1001 /* 1002 * by definition, 1KiB is 2 sectors 1003 */ 1004 back_max = cfqd->cfq_back_max * 2; 1005 1006 /* 1007 * Strict one way elevator _except_ in the case where we allow 1008 * short backward seeks which are biased as twice the cost of a 1009 * similar forward seek. 1010 */ 1011 if (s1 >= last) 1012 d1 = s1 - last; 1013 else if (s1 + back_max >= last) 1014 d1 = (last - s1) * cfqd->cfq_back_penalty; 1015 else 1016 wrap |= CFQ_RQ1_WRAP; 1017 1018 if (s2 >= last) 1019 d2 = s2 - last; 1020 else if (s2 + back_max >= last) 1021 d2 = (last - s2) * cfqd->cfq_back_penalty; 1022 else 1023 wrap |= CFQ_RQ2_WRAP; 1024 1025 /* Found required data */ 1026 1027 /* 1028 * By doing switch() on the bit mask "wrap" we avoid having to 1029 * check two variables for all permutations: --> faster! 1030 */ 1031 switch (wrap) { 1032 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 1033 if (d1 < d2) 1034 return rq1; 1035 else if (d2 < d1) 1036 return rq2; 1037 else { 1038 if (s1 >= s2) 1039 return rq1; 1040 else 1041 return rq2; 1042 } 1043 1044 case CFQ_RQ2_WRAP: 1045 return rq1; 1046 case CFQ_RQ1_WRAP: 1047 return rq2; 1048 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 1049 default: 1050 /* 1051 * Since both rqs are wrapped, 1052 * start with the one that's further behind head 1053 * (--> only *one* back seek required), 1054 * since back seek takes more time than forward. 1055 */ 1056 if (s1 <= s2) 1057 return rq1; 1058 else 1059 return rq2; 1060 } 1061} 1062 1063/* 1064 * The below is leftmost cache rbtree addon 1065 */ 1066static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 1067{ 1068 /* Service tree is empty */ 1069 if (!root->count) 1070 return NULL; 1071 1072 if (!root->left) 1073 root->left = rb_first(&root->rb); 1074 1075 if (root->left) 1076 return rb_entry(root->left, struct cfq_queue, rb_node); 1077 1078 return NULL; 1079} 1080 1081static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 1082{ 1083 if (!root->left) 1084 root->left = rb_first(&root->rb); 1085 1086 if (root->left) 1087 return rb_entry_cfqg(root->left); 1088 1089 return NULL; 1090} 1091 1092static void rb_erase_init(struct rb_node *n, struct rb_root *root) 1093{ 1094 rb_erase(n, root); 1095 RB_CLEAR_NODE(n); 1096} 1097 1098static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 1099{ 1100 if (root->left == n) 1101 root->left = NULL; 1102 rb_erase_init(n, &root->rb); 1103 --root->count; 1104} 1105 1106/* 1107 * would be nice to take fifo expire time into account as well 1108 */ 1109static struct request * 1110cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1111 struct request *last) 1112{ 1113 struct rb_node *rbnext = rb_next(&last->rb_node); 1114 struct rb_node *rbprev = rb_prev(&last->rb_node); 1115 struct request *next = NULL, *prev = NULL; 1116 1117 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 1118 1119 if (rbprev) 1120 prev = rb_entry_rq(rbprev); 1121 1122 if (rbnext) 1123 next = rb_entry_rq(rbnext); 1124 else { 1125 rbnext = rb_first(&cfqq->sort_list); 1126 if (rbnext && rbnext != &last->rb_node) 1127 next = rb_entry_rq(rbnext); 1128 } 1129 1130 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 1131} 1132 1133static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 1134 struct cfq_queue *cfqq) 1135{ 1136 /* 1137 * just an approximation, should be ok. 1138 */ 1139 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 1140 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 1141} 1142 1143static inline s64 1144cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 1145{ 1146 return cfqg->vdisktime - st->min_vdisktime; 1147} 1148 1149static void 1150__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1151{ 1152 struct rb_node **node = &st->rb.rb_node; 1153 struct rb_node *parent = NULL; 1154 struct cfq_group *__cfqg; 1155 s64 key = cfqg_key(st, cfqg); 1156 int left = 1; 1157 1158 while (*node != NULL) { 1159 parent = *node; 1160 __cfqg = rb_entry_cfqg(parent); 1161 1162 if (key < cfqg_key(st, __cfqg)) 1163 node = &parent->rb_left; 1164 else { 1165 node = &parent->rb_right; 1166 left = 0; 1167 } 1168 } 1169 1170 if (left) 1171 st->left = &cfqg->rb_node; 1172 1173 rb_link_node(&cfqg->rb_node, parent, node); 1174 rb_insert_color(&cfqg->rb_node, &st->rb); 1175} 1176 1177static void 1178cfq_update_group_weight(struct cfq_group *cfqg) 1179{ 1180 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1181 if (cfqg->new_weight) { 1182 cfqg->weight = cfqg->new_weight; 1183 cfqg->new_weight = 0; 1184 } 1185} 1186 1187static void 1188cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1189{ 1190 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1191 1192 cfq_update_group_weight(cfqg); 1193 __cfq_group_service_tree_add(st, cfqg); 1194 st->total_weight += cfqg->weight; 1195} 1196 1197static void 1198cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 1199{ 1200 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1201 struct cfq_group *__cfqg; 1202 struct rb_node *n; 1203 1204 cfqg->nr_cfqq++; 1205 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1206 return; 1207 1208 /* 1209 * Currently put the group at the end. Later implement something 1210 * so that groups get lesser vtime based on their weights, so that 1211 * if group does not loose all if it was not continuously backlogged. 1212 */ 1213 n = rb_last(&st->rb); 1214 if (n) { 1215 __cfqg = rb_entry_cfqg(n); 1216 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 1217 } else 1218 cfqg->vdisktime = st->min_vdisktime; 1219 cfq_group_service_tree_add(st, cfqg); 1220} 1221 1222static void 1223cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 1224{ 1225 st->total_weight -= cfqg->weight; 1226 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1227 cfq_rb_erase(&cfqg->rb_node, st); 1228} 1229 1230static void 1231cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 1232{ 1233 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1234 1235 BUG_ON(cfqg->nr_cfqq < 1); 1236 cfqg->nr_cfqq--; 1237 1238 /* If there are other cfq queues under this group, don't delete it */ 1239 if (cfqg->nr_cfqq) 1240 return; 1241 1242 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 1243 cfq_group_service_tree_del(st, cfqg); 1244 cfqg->saved_wl_slice = 0; 1245 cfqg_stats_update_dequeue(cfqg); 1246} 1247 1248static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 1249 unsigned int *unaccounted_time) 1250{ 1251 unsigned int slice_used; 1252 1253 /* 1254 * Queue got expired before even a single request completed or 1255 * got expired immediately after first request completion. 1256 */ 1257 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 1258 /* 1259 * Also charge the seek time incurred to the group, otherwise 1260 * if there are mutiple queues in the group, each can dispatch 1261 * a single request on seeky media and cause lots of seek time 1262 * and group will never know it. 1263 */ 1264 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 1265 1); 1266 } else { 1267 slice_used = jiffies - cfqq->slice_start; 1268 if (slice_used > cfqq->allocated_slice) { 1269 *unaccounted_time = slice_used - cfqq->allocated_slice; 1270 slice_used = cfqq->allocated_slice; 1271 } 1272 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 1273 *unaccounted_time += cfqq->slice_start - 1274 cfqq->dispatch_start; 1275 } 1276 1277 return slice_used; 1278} 1279 1280static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 1281 struct cfq_queue *cfqq) 1282{ 1283 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1284 unsigned int used_sl, charge, unaccounted_sl = 0; 1285 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 1286 - cfqg->service_tree_idle.count; 1287 1288 BUG_ON(nr_sync < 0); 1289 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 1290 1291 if (iops_mode(cfqd)) 1292 charge = cfqq->slice_dispatch; 1293 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 1294 charge = cfqq->allocated_slice; 1295 1296 /* Can't update vdisktime while group is on service tree */ 1297 cfq_group_service_tree_del(st, cfqg); 1298 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 1299 /* If a new weight was requested, update now, off tree */ 1300 cfq_group_service_tree_add(st, cfqg); 1301 1302 /* This group is being expired. Save the context */ 1303 if (time_after(cfqd->workload_expires, jiffies)) { 1304 cfqg->saved_wl_slice = cfqd->workload_expires 1305 - jiffies; 1306 cfqg->saved_wl_type = cfqd->serving_wl_type; 1307 cfqg->saved_wl_class = cfqd->serving_wl_class; 1308 } else 1309 cfqg->saved_wl_slice = 0; 1310 1311 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 1312 st->min_vdisktime); 1313 cfq_log_cfqq(cfqq->cfqd, cfqq, 1314 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 1315 used_sl, cfqq->slice_dispatch, charge, 1316 iops_mode(cfqd), cfqq->nr_sectors); 1317 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl); 1318 cfqg_stats_set_start_empty_time(cfqg); 1319} 1320 1321/** 1322 * cfq_init_cfqg_base - initialize base part of a cfq_group 1323 * @cfqg: cfq_group to initialize 1324 * 1325 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED 1326 * is enabled or not. 1327 */ 1328static void cfq_init_cfqg_base(struct cfq_group *cfqg) 1329{ 1330 struct cfq_rb_root *st; 1331 int i, j; 1332 1333 for_each_cfqg_st(cfqg, i, j, st) 1334 *st = CFQ_RB_ROOT; 1335 RB_CLEAR_NODE(&cfqg->rb_node); 1336 1337 cfqg->ttime.last_end_request = jiffies; 1338} 1339 1340#ifdef CONFIG_CFQ_GROUP_IOSCHED 1341static void cfq_pd_init(struct blkcg_gq *blkg) 1342{ 1343 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1344 1345 cfq_init_cfqg_base(cfqg); 1346 cfqg->weight = blkg->blkcg->cfq_weight; 1347} 1348 1349/* 1350 * Search for the cfq group current task belongs to. request_queue lock must 1351 * be held. 1352 */ 1353static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1354 struct blkcg *blkcg) 1355{ 1356 struct request_queue *q = cfqd->queue; 1357 struct cfq_group *cfqg = NULL; 1358 1359 /* avoid lookup for the common case where there's no blkcg */ 1360 if (blkcg == &blkcg_root) { 1361 cfqg = cfqd->root_group; 1362 } else { 1363 struct blkcg_gq *blkg; 1364 1365 blkg = blkg_lookup_create(blkcg, q); 1366 if (!IS_ERR(blkg)) 1367 cfqg = blkg_to_cfqg(blkg); 1368 } 1369 1370 return cfqg; 1371} 1372 1373static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1374{ 1375 /* Currently, all async queues are mapped to root group */ 1376 if (!cfq_cfqq_sync(cfqq)) 1377 cfqg = cfqq->cfqd->root_group; 1378 1379 cfqq->cfqg = cfqg; 1380 /* cfqq reference on cfqg */ 1381 cfqg_get(cfqg); 1382} 1383 1384static u64 cfqg_prfill_weight_device(struct seq_file *sf, 1385 struct blkg_policy_data *pd, int off) 1386{ 1387 struct cfq_group *cfqg = pd_to_cfqg(pd); 1388 1389 if (!cfqg->dev_weight) 1390 return 0; 1391 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight); 1392} 1393 1394static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft, 1395 struct seq_file *sf) 1396{ 1397 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), 1398 cfqg_prfill_weight_device, &blkcg_policy_cfq, 0, 1399 false); 1400 return 0; 1401} 1402 1403static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft, 1404 struct seq_file *sf) 1405{ 1406 seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight); 1407 return 0; 1408} 1409 1410static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft, 1411 const char *buf) 1412{ 1413 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1414 struct blkg_conf_ctx ctx; 1415 struct cfq_group *cfqg; 1416 int ret; 1417 1418 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx); 1419 if (ret) 1420 return ret; 1421 1422 ret = -EINVAL; 1423 cfqg = blkg_to_cfqg(ctx.blkg); 1424 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) { 1425 cfqg->dev_weight = ctx.v; 1426 cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight; 1427 ret = 0; 1428 } 1429 1430 blkg_conf_finish(&ctx); 1431 return ret; 1432} 1433 1434static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val) 1435{ 1436 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1437 struct blkcg_gq *blkg; 1438 struct hlist_node *n; 1439 1440 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX) 1441 return -EINVAL; 1442 1443 spin_lock_irq(&blkcg->lock); 1444 blkcg->cfq_weight = (unsigned int)val; 1445 1446 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { 1447 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1448 1449 if (cfqg && !cfqg->dev_weight) 1450 cfqg->new_weight = blkcg->cfq_weight; 1451 } 1452 1453 spin_unlock_irq(&blkcg->lock); 1454 return 0; 1455} 1456 1457static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft, 1458 struct seq_file *sf) 1459{ 1460 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1461 1462 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq, 1463 cft->private, false); 1464 return 0; 1465} 1466 1467static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft, 1468 struct seq_file *sf) 1469{ 1470 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1471 1472 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq, 1473 cft->private, true); 1474 return 0; 1475} 1476 1477#ifdef CONFIG_DEBUG_BLK_CGROUP 1478static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, 1479 struct blkg_policy_data *pd, int off) 1480{ 1481 struct cfq_group *cfqg = pd_to_cfqg(pd); 1482 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples); 1483 u64 v = 0; 1484 1485 if (samples) { 1486 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum); 1487 do_div(v, samples); 1488 } 1489 __blkg_prfill_u64(sf, pd, v); 1490 return 0; 1491} 1492 1493/* print avg_queue_size */ 1494static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft, 1495 struct seq_file *sf) 1496{ 1497 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1498 1499 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size, 1500 &blkcg_policy_cfq, 0, false); 1501 return 0; 1502} 1503#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1504 1505static struct cftype cfq_blkcg_files[] = { 1506 { 1507 .name = "weight_device", 1508 .read_seq_string = cfqg_print_weight_device, 1509 .write_string = cfqg_set_weight_device, 1510 .max_write_len = 256, 1511 }, 1512 { 1513 .name = "weight", 1514 .read_seq_string = cfq_print_weight, 1515 .write_u64 = cfq_set_weight, 1516 }, 1517 { 1518 .name = "time", 1519 .private = offsetof(struct cfq_group, stats.time), 1520 .read_seq_string = cfqg_print_stat, 1521 }, 1522 { 1523 .name = "sectors", 1524 .private = offsetof(struct cfq_group, stats.sectors), 1525 .read_seq_string = cfqg_print_stat, 1526 }, 1527 { 1528 .name = "io_service_bytes", 1529 .private = offsetof(struct cfq_group, stats.service_bytes), 1530 .read_seq_string = cfqg_print_rwstat, 1531 }, 1532 { 1533 .name = "io_serviced", 1534 .private = offsetof(struct cfq_group, stats.serviced), 1535 .read_seq_string = cfqg_print_rwstat, 1536 }, 1537 { 1538 .name = "io_service_time", 1539 .private = offsetof(struct cfq_group, stats.service_time), 1540 .read_seq_string = cfqg_print_rwstat, 1541 }, 1542 { 1543 .name = "io_wait_time", 1544 .private = offsetof(struct cfq_group, stats.wait_time), 1545 .read_seq_string = cfqg_print_rwstat, 1546 }, 1547 { 1548 .name = "io_merged", 1549 .private = offsetof(struct cfq_group, stats.merged), 1550 .read_seq_string = cfqg_print_rwstat, 1551 }, 1552 { 1553 .name = "io_queued", 1554 .private = offsetof(struct cfq_group, stats.queued), 1555 .read_seq_string = cfqg_print_rwstat, 1556 }, 1557#ifdef CONFIG_DEBUG_BLK_CGROUP 1558 { 1559 .name = "avg_queue_size", 1560 .read_seq_string = cfqg_print_avg_queue_size, 1561 }, 1562 { 1563 .name = "group_wait_time", 1564 .private = offsetof(struct cfq_group, stats.group_wait_time), 1565 .read_seq_string = cfqg_print_stat, 1566 }, 1567 { 1568 .name = "idle_time", 1569 .private = offsetof(struct cfq_group, stats.idle_time), 1570 .read_seq_string = cfqg_print_stat, 1571 }, 1572 { 1573 .name = "empty_time", 1574 .private = offsetof(struct cfq_group, stats.empty_time), 1575 .read_seq_string = cfqg_print_stat, 1576 }, 1577 { 1578 .name = "dequeue", 1579 .private = offsetof(struct cfq_group, stats.dequeue), 1580 .read_seq_string = cfqg_print_stat, 1581 }, 1582 { 1583 .name = "unaccounted_time", 1584 .private = offsetof(struct cfq_group, stats.unaccounted_time), 1585 .read_seq_string = cfqg_print_stat, 1586 }, 1587#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1588 { } /* terminate */ 1589}; 1590#else /* GROUP_IOSCHED */ 1591static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1592 struct blkcg *blkcg) 1593{ 1594 return cfqd->root_group; 1595} 1596 1597static inline void 1598cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1599 cfqq->cfqg = cfqg; 1600} 1601 1602#endif /* GROUP_IOSCHED */ 1603 1604/* 1605 * The cfqd->service_trees holds all pending cfq_queue's that have 1606 * requests waiting to be processed. It is sorted in the order that 1607 * we will service the queues. 1608 */ 1609static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1610 bool add_front) 1611{ 1612 struct rb_node **p, *parent; 1613 struct cfq_queue *__cfqq; 1614 unsigned long rb_key; 1615 struct cfq_rb_root *st; 1616 int left; 1617 int new_cfqq = 1; 1618 1619 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq)); 1620 if (cfq_class_idle(cfqq)) { 1621 rb_key = CFQ_IDLE_DELAY; 1622 parent = rb_last(&st->rb); 1623 if (parent && parent != &cfqq->rb_node) { 1624 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1625 rb_key += __cfqq->rb_key; 1626 } else 1627 rb_key += jiffies; 1628 } else if (!add_front) { 1629 /* 1630 * Get our rb key offset. Subtract any residual slice 1631 * value carried from last service. A negative resid 1632 * count indicates slice overrun, and this should position 1633 * the next service time further away in the tree. 1634 */ 1635 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1636 rb_key -= cfqq->slice_resid; 1637 cfqq->slice_resid = 0; 1638 } else { 1639 rb_key = -HZ; 1640 __cfqq = cfq_rb_first(st); 1641 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1642 } 1643 1644 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1645 new_cfqq = 0; 1646 /* 1647 * same position, nothing more to do 1648 */ 1649 if (rb_key == cfqq->rb_key && cfqq->service_tree == st) 1650 return; 1651 1652 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1653 cfqq->service_tree = NULL; 1654 } 1655 1656 left = 1; 1657 parent = NULL; 1658 cfqq->service_tree = st; 1659 p = &st->rb.rb_node; 1660 while (*p) { 1661 struct rb_node **n; 1662 1663 parent = *p; 1664 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1665 1666 /* 1667 * sort by key, that represents service time. 1668 */ 1669 if (time_before(rb_key, __cfqq->rb_key)) 1670 n = &(*p)->rb_left; 1671 else { 1672 n = &(*p)->rb_right; 1673 left = 0; 1674 } 1675 1676 p = n; 1677 } 1678 1679 if (left) 1680 st->left = &cfqq->rb_node; 1681 1682 cfqq->rb_key = rb_key; 1683 rb_link_node(&cfqq->rb_node, parent, p); 1684 rb_insert_color(&cfqq->rb_node, &st->rb); 1685 st->count++; 1686 if (add_front || !new_cfqq) 1687 return; 1688 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1689} 1690 1691static struct cfq_queue * 1692cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1693 sector_t sector, struct rb_node **ret_parent, 1694 struct rb_node ***rb_link) 1695{ 1696 struct rb_node **p, *parent; 1697 struct cfq_queue *cfqq = NULL; 1698 1699 parent = NULL; 1700 p = &root->rb_node; 1701 while (*p) { 1702 struct rb_node **n; 1703 1704 parent = *p; 1705 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1706 1707 /* 1708 * Sort strictly based on sector. Smallest to the left, 1709 * largest to the right. 1710 */ 1711 if (sector > blk_rq_pos(cfqq->next_rq)) 1712 n = &(*p)->rb_right; 1713 else if (sector < blk_rq_pos(cfqq->next_rq)) 1714 n = &(*p)->rb_left; 1715 else 1716 break; 1717 p = n; 1718 cfqq = NULL; 1719 } 1720 1721 *ret_parent = parent; 1722 if (rb_link) 1723 *rb_link = p; 1724 return cfqq; 1725} 1726 1727static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1728{ 1729 struct rb_node **p, *parent; 1730 struct cfq_queue *__cfqq; 1731 1732 if (cfqq->p_root) { 1733 rb_erase(&cfqq->p_node, cfqq->p_root); 1734 cfqq->p_root = NULL; 1735 } 1736 1737 if (cfq_class_idle(cfqq)) 1738 return; 1739 if (!cfqq->next_rq) 1740 return; 1741 1742 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1743 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1744 blk_rq_pos(cfqq->next_rq), &parent, &p); 1745 if (!__cfqq) { 1746 rb_link_node(&cfqq->p_node, parent, p); 1747 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1748 } else 1749 cfqq->p_root = NULL; 1750} 1751 1752/* 1753 * Update cfqq's position in the service tree. 1754 */ 1755static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1756{ 1757 /* 1758 * Resorting requires the cfqq to be on the RR list already. 1759 */ 1760 if (cfq_cfqq_on_rr(cfqq)) { 1761 cfq_service_tree_add(cfqd, cfqq, 0); 1762 cfq_prio_tree_add(cfqd, cfqq); 1763 } 1764} 1765 1766/* 1767 * add to busy list of queues for service, trying to be fair in ordering 1768 * the pending list according to last request service 1769 */ 1770static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1771{ 1772 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1773 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1774 cfq_mark_cfqq_on_rr(cfqq); 1775 cfqd->busy_queues++; 1776 if (cfq_cfqq_sync(cfqq)) 1777 cfqd->busy_sync_queues++; 1778 1779 cfq_resort_rr_list(cfqd, cfqq); 1780} 1781 1782/* 1783 * Called when the cfqq no longer has requests pending, remove it from 1784 * the service tree. 1785 */ 1786static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1787{ 1788 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1789 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1790 cfq_clear_cfqq_on_rr(cfqq); 1791 1792 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1793 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1794 cfqq->service_tree = NULL; 1795 } 1796 if (cfqq->p_root) { 1797 rb_erase(&cfqq->p_node, cfqq->p_root); 1798 cfqq->p_root = NULL; 1799 } 1800 1801 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1802 BUG_ON(!cfqd->busy_queues); 1803 cfqd->busy_queues--; 1804 if (cfq_cfqq_sync(cfqq)) 1805 cfqd->busy_sync_queues--; 1806} 1807 1808/* 1809 * rb tree support functions 1810 */ 1811static void cfq_del_rq_rb(struct request *rq) 1812{ 1813 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1814 const int sync = rq_is_sync(rq); 1815 1816 BUG_ON(!cfqq->queued[sync]); 1817 cfqq->queued[sync]--; 1818 1819 elv_rb_del(&cfqq->sort_list, rq); 1820 1821 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1822 /* 1823 * Queue will be deleted from service tree when we actually 1824 * expire it later. Right now just remove it from prio tree 1825 * as it is empty. 1826 */ 1827 if (cfqq->p_root) { 1828 rb_erase(&cfqq->p_node, cfqq->p_root); 1829 cfqq->p_root = NULL; 1830 } 1831 } 1832} 1833 1834static void cfq_add_rq_rb(struct request *rq) 1835{ 1836 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1837 struct cfq_data *cfqd = cfqq->cfqd; 1838 struct request *prev; 1839 1840 cfqq->queued[rq_is_sync(rq)]++; 1841 1842 elv_rb_add(&cfqq->sort_list, rq); 1843 1844 if (!cfq_cfqq_on_rr(cfqq)) 1845 cfq_add_cfqq_rr(cfqd, cfqq); 1846 1847 /* 1848 * check if this request is a better next-serve candidate 1849 */ 1850 prev = cfqq->next_rq; 1851 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1852 1853 /* 1854 * adjust priority tree position, if ->next_rq changes 1855 */ 1856 if (prev != cfqq->next_rq) 1857 cfq_prio_tree_add(cfqd, cfqq); 1858 1859 BUG_ON(!cfqq->next_rq); 1860} 1861 1862static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1863{ 1864 elv_rb_del(&cfqq->sort_list, rq); 1865 cfqq->queued[rq_is_sync(rq)]--; 1866 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 1867 cfq_add_rq_rb(rq); 1868 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group, 1869 rq->cmd_flags); 1870} 1871 1872static struct request * 1873cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1874{ 1875 struct task_struct *tsk = current; 1876 struct cfq_io_cq *cic; 1877 struct cfq_queue *cfqq; 1878 1879 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1880 if (!cic) 1881 return NULL; 1882 1883 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1884 if (cfqq) { 1885 sector_t sector = bio->bi_sector + bio_sectors(bio); 1886 1887 return elv_rb_find(&cfqq->sort_list, sector); 1888 } 1889 1890 return NULL; 1891} 1892 1893static void cfq_activate_request(struct request_queue *q, struct request *rq) 1894{ 1895 struct cfq_data *cfqd = q->elevator->elevator_data; 1896 1897 cfqd->rq_in_driver++; 1898 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1899 cfqd->rq_in_driver); 1900 1901 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1902} 1903 1904static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1905{ 1906 struct cfq_data *cfqd = q->elevator->elevator_data; 1907 1908 WARN_ON(!cfqd->rq_in_driver); 1909 cfqd->rq_in_driver--; 1910 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1911 cfqd->rq_in_driver); 1912} 1913 1914static void cfq_remove_request(struct request *rq) 1915{ 1916 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1917 1918 if (cfqq->next_rq == rq) 1919 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1920 1921 list_del_init(&rq->queuelist); 1922 cfq_del_rq_rb(rq); 1923 1924 cfqq->cfqd->rq_queued--; 1925 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 1926 if (rq->cmd_flags & REQ_PRIO) { 1927 WARN_ON(!cfqq->prio_pending); 1928 cfqq->prio_pending--; 1929 } 1930} 1931 1932static int cfq_merge(struct request_queue *q, struct request **req, 1933 struct bio *bio) 1934{ 1935 struct cfq_data *cfqd = q->elevator->elevator_data; 1936 struct request *__rq; 1937 1938 __rq = cfq_find_rq_fmerge(cfqd, bio); 1939 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1940 *req = __rq; 1941 return ELEVATOR_FRONT_MERGE; 1942 } 1943 1944 return ELEVATOR_NO_MERGE; 1945} 1946 1947static void cfq_merged_request(struct request_queue *q, struct request *req, 1948 int type) 1949{ 1950 if (type == ELEVATOR_FRONT_MERGE) { 1951 struct cfq_queue *cfqq = RQ_CFQQ(req); 1952 1953 cfq_reposition_rq_rb(cfqq, req); 1954 } 1955} 1956 1957static void cfq_bio_merged(struct request_queue *q, struct request *req, 1958 struct bio *bio) 1959{ 1960 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw); 1961} 1962 1963static void 1964cfq_merged_requests(struct request_queue *q, struct request *rq, 1965 struct request *next) 1966{ 1967 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1968 struct cfq_data *cfqd = q->elevator->elevator_data; 1969 1970 /* 1971 * reposition in fifo if next is older than rq 1972 */ 1973 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1974 time_before(rq_fifo_time(next), rq_fifo_time(rq)) && 1975 cfqq == RQ_CFQQ(next)) { 1976 list_move(&rq->queuelist, &next->queuelist); 1977 rq_set_fifo_time(rq, rq_fifo_time(next)); 1978 } 1979 1980 if (cfqq->next_rq == next) 1981 cfqq->next_rq = rq; 1982 cfq_remove_request(next); 1983 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags); 1984 1985 cfqq = RQ_CFQQ(next); 1986 /* 1987 * all requests of this queue are merged to other queues, delete it 1988 * from the service tree. If it's the active_queue, 1989 * cfq_dispatch_requests() will choose to expire it or do idle 1990 */ 1991 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && 1992 cfqq != cfqd->active_queue) 1993 cfq_del_cfqq_rr(cfqd, cfqq); 1994} 1995 1996static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1997 struct bio *bio) 1998{ 1999 struct cfq_data *cfqd = q->elevator->elevator_data; 2000 struct cfq_io_cq *cic; 2001 struct cfq_queue *cfqq; 2002 2003 /* 2004 * Disallow merge of a sync bio into an async request. 2005 */ 2006 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 2007 return false; 2008 2009 /* 2010 * Lookup the cfqq that this bio will be queued with and allow 2011 * merge only if rq is queued there. 2012 */ 2013 cic = cfq_cic_lookup(cfqd, current->io_context); 2014 if (!cic) 2015 return false; 2016 2017 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 2018 return cfqq == RQ_CFQQ(rq); 2019} 2020 2021static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2022{ 2023 del_timer(&cfqd->idle_slice_timer); 2024 cfqg_stats_update_idle_time(cfqq->cfqg); 2025} 2026 2027static void __cfq_set_active_queue(struct cfq_data *cfqd, 2028 struct cfq_queue *cfqq) 2029{ 2030 if (cfqq) { 2031 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d", 2032 cfqd->serving_wl_class, cfqd->serving_wl_type); 2033 cfqg_stats_update_avg_queue_size(cfqq->cfqg); 2034 cfqq->slice_start = 0; 2035 cfqq->dispatch_start = jiffies; 2036 cfqq->allocated_slice = 0; 2037 cfqq->slice_end = 0; 2038 cfqq->slice_dispatch = 0; 2039 cfqq->nr_sectors = 0; 2040 2041 cfq_clear_cfqq_wait_request(cfqq); 2042 cfq_clear_cfqq_must_dispatch(cfqq); 2043 cfq_clear_cfqq_must_alloc_slice(cfqq); 2044 cfq_clear_cfqq_fifo_expire(cfqq); 2045 cfq_mark_cfqq_slice_new(cfqq); 2046 2047 cfq_del_timer(cfqd, cfqq); 2048 } 2049 2050 cfqd->active_queue = cfqq; 2051} 2052 2053/* 2054 * current cfqq expired its slice (or was too idle), select new one 2055 */ 2056static void 2057__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2058 bool timed_out) 2059{ 2060 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 2061 2062 if (cfq_cfqq_wait_request(cfqq)) 2063 cfq_del_timer(cfqd, cfqq); 2064 2065 cfq_clear_cfqq_wait_request(cfqq); 2066 cfq_clear_cfqq_wait_busy(cfqq); 2067 2068 /* 2069 * If this cfqq is shared between multiple processes, check to 2070 * make sure that those processes are still issuing I/Os within 2071 * the mean seek distance. If not, it may be time to break the 2072 * queues apart again. 2073 */ 2074 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 2075 cfq_mark_cfqq_split_coop(cfqq); 2076 2077 /* 2078 * store what was left of this slice, if the queue idled/timed out 2079 */ 2080 if (timed_out) { 2081 if (cfq_cfqq_slice_new(cfqq)) 2082 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 2083 else 2084 cfqq->slice_resid = cfqq->slice_end - jiffies; 2085 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 2086 } 2087 2088 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 2089 2090 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 2091 cfq_del_cfqq_rr(cfqd, cfqq); 2092 2093 cfq_resort_rr_list(cfqd, cfqq); 2094 2095 if (cfqq == cfqd->active_queue) 2096 cfqd->active_queue = NULL; 2097 2098 if (cfqd->active_cic) { 2099 put_io_context(cfqd->active_cic->icq.ioc); 2100 cfqd->active_cic = NULL; 2101 } 2102} 2103 2104static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 2105{ 2106 struct cfq_queue *cfqq = cfqd->active_queue; 2107 2108 if (cfqq) 2109 __cfq_slice_expired(cfqd, cfqq, timed_out); 2110} 2111 2112/* 2113 * Get next queue for service. Unless we have a queue preemption, 2114 * we'll simply select the first cfqq in the service tree. 2115 */ 2116static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 2117{ 2118 struct cfq_rb_root *st = st_for(cfqd->serving_group, 2119 cfqd->serving_wl_class, cfqd->serving_wl_type); 2120 2121 if (!cfqd->rq_queued) 2122 return NULL; 2123 2124 /* There is nothing to dispatch */ 2125 if (!st) 2126 return NULL; 2127 if (RB_EMPTY_ROOT(&st->rb)) 2128 return NULL; 2129 return cfq_rb_first(st); 2130} 2131 2132static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 2133{ 2134 struct cfq_group *cfqg; 2135 struct cfq_queue *cfqq; 2136 int i, j; 2137 struct cfq_rb_root *st; 2138 2139 if (!cfqd->rq_queued) 2140 return NULL; 2141 2142 cfqg = cfq_get_next_cfqg(cfqd); 2143 if (!cfqg) 2144 return NULL; 2145 2146 for_each_cfqg_st(cfqg, i, j, st) 2147 if ((cfqq = cfq_rb_first(st)) != NULL) 2148 return cfqq; 2149 return NULL; 2150} 2151 2152/* 2153 * Get and set a new active queue for service. 2154 */ 2155static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 2156 struct cfq_queue *cfqq) 2157{ 2158 if (!cfqq) 2159 cfqq = cfq_get_next_queue(cfqd); 2160 2161 __cfq_set_active_queue(cfqd, cfqq); 2162 return cfqq; 2163} 2164 2165static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 2166 struct request *rq) 2167{ 2168 if (blk_rq_pos(rq) >= cfqd->last_position) 2169 return blk_rq_pos(rq) - cfqd->last_position; 2170 else 2171 return cfqd->last_position - blk_rq_pos(rq); 2172} 2173 2174static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2175 struct request *rq) 2176{ 2177 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 2178} 2179 2180static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 2181 struct cfq_queue *cur_cfqq) 2182{ 2183 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 2184 struct rb_node *parent, *node; 2185 struct cfq_queue *__cfqq; 2186 sector_t sector = cfqd->last_position; 2187 2188 if (RB_EMPTY_ROOT(root)) 2189 return NULL; 2190 2191 /* 2192 * First, if we find a request starting at the end of the last 2193 * request, choose it. 2194 */ 2195 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 2196 if (__cfqq) 2197 return __cfqq; 2198 2199 /* 2200 * If the exact sector wasn't found, the parent of the NULL leaf 2201 * will contain the closest sector. 2202 */ 2203 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 2204 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2205 return __cfqq; 2206 2207 if (blk_rq_pos(__cfqq->next_rq) < sector) 2208 node = rb_next(&__cfqq->p_node); 2209 else 2210 node = rb_prev(&__cfqq->p_node); 2211 if (!node) 2212 return NULL; 2213 2214 __cfqq = rb_entry(node, struct cfq_queue, p_node); 2215 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2216 return __cfqq; 2217 2218 return NULL; 2219} 2220 2221/* 2222 * cfqd - obvious 2223 * cur_cfqq - passed in so that we don't decide that the current queue is 2224 * closely cooperating with itself. 2225 * 2226 * So, basically we're assuming that that cur_cfqq has dispatched at least 2227 * one request, and that cfqd->last_position reflects a position on the disk 2228 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 2229 * assumption. 2230 */ 2231static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 2232 struct cfq_queue *cur_cfqq) 2233{ 2234 struct cfq_queue *cfqq; 2235 2236 if (cfq_class_idle(cur_cfqq)) 2237 return NULL; 2238 if (!cfq_cfqq_sync(cur_cfqq)) 2239 return NULL; 2240 if (CFQQ_SEEKY(cur_cfqq)) 2241 return NULL; 2242 2243 /* 2244 * Don't search priority tree if it's the only queue in the group. 2245 */ 2246 if (cur_cfqq->cfqg->nr_cfqq == 1) 2247 return NULL; 2248 2249 /* 2250 * We should notice if some of the queues are cooperating, eg 2251 * working closely on the same area of the disk. In that case, 2252 * we can group them together and don't waste time idling. 2253 */ 2254 cfqq = cfqq_close(cfqd, cur_cfqq); 2255 if (!cfqq) 2256 return NULL; 2257 2258 /* If new queue belongs to different cfq_group, don't choose it */ 2259 if (cur_cfqq->cfqg != cfqq->cfqg) 2260 return NULL; 2261 2262 /* 2263 * It only makes sense to merge sync queues. 2264 */ 2265 if (!cfq_cfqq_sync(cfqq)) 2266 return NULL; 2267 if (CFQQ_SEEKY(cfqq)) 2268 return NULL; 2269 2270 /* 2271 * Do not merge queues of different priority classes 2272 */ 2273 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 2274 return NULL; 2275 2276 return cfqq; 2277} 2278 2279/* 2280 * Determine whether we should enforce idle window for this queue. 2281 */ 2282 2283static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2284{ 2285 enum wl_class_t wl_class = cfqq_class(cfqq); 2286 struct cfq_rb_root *st = cfqq->service_tree; 2287 2288 BUG_ON(!st); 2289 BUG_ON(!st->count); 2290 2291 if (!cfqd->cfq_slice_idle) 2292 return false; 2293 2294 /* We never do for idle class queues. */ 2295 if (wl_class == IDLE_WORKLOAD) 2296 return false; 2297 2298 /* We do for queues that were marked with idle window flag. */ 2299 if (cfq_cfqq_idle_window(cfqq) && 2300 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 2301 return true; 2302 2303 /* 2304 * Otherwise, we do only if they are the last ones 2305 * in their service tree. 2306 */ 2307 if (st->count == 1 && cfq_cfqq_sync(cfqq) && 2308 !cfq_io_thinktime_big(cfqd, &st->ttime, false)) 2309 return true; 2310 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count); 2311 return false; 2312} 2313 2314static void cfq_arm_slice_timer(struct cfq_data *cfqd) 2315{ 2316 struct cfq_queue *cfqq = cfqd->active_queue; 2317 struct cfq_io_cq *cic; 2318 unsigned long sl, group_idle = 0; 2319 2320 /* 2321 * SSD device without seek penalty, disable idling. But only do so 2322 * for devices that support queuing, otherwise we still have a problem 2323 * with sync vs async workloads. 2324 */ 2325 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 2326 return; 2327 2328 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 2329 WARN_ON(cfq_cfqq_slice_new(cfqq)); 2330 2331 /* 2332 * idle is disabled, either manually or by past process history 2333 */ 2334 if (!cfq_should_idle(cfqd, cfqq)) { 2335 /* no queue idling. Check for group idling */ 2336 if (cfqd->cfq_group_idle) 2337 group_idle = cfqd->cfq_group_idle; 2338 else 2339 return; 2340 } 2341 2342 /* 2343 * still active requests from this queue, don't idle 2344 */ 2345 if (cfqq->dispatched) 2346 return; 2347 2348 /* 2349 * task has exited, don't wait 2350 */ 2351 cic = cfqd->active_cic; 2352 if (!cic || !atomic_read(&cic->icq.ioc->active_ref)) 2353 return; 2354 2355 /* 2356 * If our average think time is larger than the remaining time 2357 * slice, then don't idle. This avoids overrunning the allotted 2358 * time slice. 2359 */ 2360 if (sample_valid(cic->ttime.ttime_samples) && 2361 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { 2362 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2363 cic->ttime.ttime_mean); 2364 return; 2365 } 2366 2367 /* There are other queues in the group, don't do group idle */ 2368 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2369 return; 2370 2371 cfq_mark_cfqq_wait_request(cfqq); 2372 2373 if (group_idle) 2374 sl = cfqd->cfq_group_idle; 2375 else 2376 sl = cfqd->cfq_slice_idle; 2377 2378 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2379 cfqg_stats_set_start_idle_time(cfqq->cfqg); 2380 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2381 group_idle ? 1 : 0); 2382} 2383 2384/* 2385 * Move request from internal lists to the request queue dispatch list. 2386 */ 2387static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2388{ 2389 struct cfq_data *cfqd = q->elevator->elevator_data; 2390 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2391 2392 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2393 2394 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2395 cfq_remove_request(rq); 2396 cfqq->dispatched++; 2397 (RQ_CFQG(rq))->dispatched++; 2398 elv_dispatch_sort(q, rq); 2399 2400 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2401 cfqq->nr_sectors += blk_rq_sectors(rq); 2402 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags); 2403} 2404 2405/* 2406 * return expired entry, or NULL to just start from scratch in rbtree 2407 */ 2408static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2409{ 2410 struct request *rq = NULL; 2411 2412 if (cfq_cfqq_fifo_expire(cfqq)) 2413 return NULL; 2414 2415 cfq_mark_cfqq_fifo_expire(cfqq); 2416 2417 if (list_empty(&cfqq->fifo)) 2418 return NULL; 2419 2420 rq = rq_entry_fifo(cfqq->fifo.next); 2421 if (time_before(jiffies, rq_fifo_time(rq))) 2422 rq = NULL; 2423 2424 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2425 return rq; 2426} 2427 2428static inline int 2429cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2430{ 2431 const int base_rq = cfqd->cfq_slice_async_rq; 2432 2433 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2434 2435 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2436} 2437 2438/* 2439 * Must be called with the queue_lock held. 2440 */ 2441static int cfqq_process_refs(struct cfq_queue *cfqq) 2442{ 2443 int process_refs, io_refs; 2444 2445 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2446 process_refs = cfqq->ref - io_refs; 2447 BUG_ON(process_refs < 0); 2448 return process_refs; 2449} 2450 2451static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2452{ 2453 int process_refs, new_process_refs; 2454 struct cfq_queue *__cfqq; 2455 2456 /* 2457 * If there are no process references on the new_cfqq, then it is 2458 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2459 * chain may have dropped their last reference (not just their 2460 * last process reference). 2461 */ 2462 if (!cfqq_process_refs(new_cfqq)) 2463 return; 2464 2465 /* Avoid a circular list and skip interim queue merges */ 2466 while ((__cfqq = new_cfqq->new_cfqq)) { 2467 if (__cfqq == cfqq) 2468 return; 2469 new_cfqq = __cfqq; 2470 } 2471 2472 process_refs = cfqq_process_refs(cfqq); 2473 new_process_refs = cfqq_process_refs(new_cfqq); 2474 /* 2475 * If the process for the cfqq has gone away, there is no 2476 * sense in merging the queues. 2477 */ 2478 if (process_refs == 0 || new_process_refs == 0) 2479 return; 2480 2481 /* 2482 * Merge in the direction of the lesser amount of work. 2483 */ 2484 if (new_process_refs >= process_refs) { 2485 cfqq->new_cfqq = new_cfqq; 2486 new_cfqq->ref += process_refs; 2487 } else { 2488 new_cfqq->new_cfqq = cfqq; 2489 cfqq->ref += new_process_refs; 2490 } 2491} 2492 2493static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd, 2494 struct cfq_group *cfqg, enum wl_class_t wl_class) 2495{ 2496 struct cfq_queue *queue; 2497 int i; 2498 bool key_valid = false; 2499 unsigned long lowest_key = 0; 2500 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2501 2502 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2503 /* select the one with lowest rb_key */ 2504 queue = cfq_rb_first(st_for(cfqg, wl_class, i)); 2505 if (queue && 2506 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2507 lowest_key = queue->rb_key; 2508 cur_best = i; 2509 key_valid = true; 2510 } 2511 } 2512 2513 return cur_best; 2514} 2515 2516static void 2517choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg) 2518{ 2519 unsigned slice; 2520 unsigned count; 2521 struct cfq_rb_root *st; 2522 unsigned group_slice; 2523 enum wl_class_t original_class = cfqd->serving_wl_class; 2524 2525 /* Choose next priority. RT > BE > IDLE */ 2526 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2527 cfqd->serving_wl_class = RT_WORKLOAD; 2528 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2529 cfqd->serving_wl_class = BE_WORKLOAD; 2530 else { 2531 cfqd->serving_wl_class = IDLE_WORKLOAD; 2532 cfqd->workload_expires = jiffies + 1; 2533 return; 2534 } 2535 2536 if (original_class != cfqd->serving_wl_class) 2537 goto new_workload; 2538 2539 /* 2540 * For RT and BE, we have to choose also the type 2541 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2542 * expiration time 2543 */ 2544 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type); 2545 count = st->count; 2546 2547 /* 2548 * check workload expiration, and that we still have other queues ready 2549 */ 2550 if (count && !time_after(jiffies, cfqd->workload_expires)) 2551 return; 2552 2553new_workload: 2554 /* otherwise select new workload type */ 2555 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg, 2556 cfqd->serving_wl_class); 2557 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type); 2558 count = st->count; 2559 2560 /* 2561 * the workload slice is computed as a fraction of target latency 2562 * proportional to the number of queues in that workload, over 2563 * all the queues in the same priority class 2564 */ 2565 group_slice = cfq_group_slice(cfqd, cfqg); 2566 2567 slice = group_slice * count / 2568 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class], 2569 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd, 2570 cfqg)); 2571 2572 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) { 2573 unsigned int tmp; 2574 2575 /* 2576 * Async queues are currently system wide. Just taking 2577 * proportion of queues with-in same group will lead to higher 2578 * async ratio system wide as generally root group is going 2579 * to have higher weight. A more accurate thing would be to 2580 * calculate system wide asnc/sync ratio. 2581 */ 2582 tmp = cfqd->cfq_target_latency * 2583 cfqg_busy_async_queues(cfqd, cfqg); 2584 tmp = tmp/cfqd->busy_queues; 2585 slice = min_t(unsigned, slice, tmp); 2586 2587 /* async workload slice is scaled down according to 2588 * the sync/async slice ratio. */ 2589 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2590 } else 2591 /* sync workload slice is at least 2 * cfq_slice_idle */ 2592 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2593 2594 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2595 cfq_log(cfqd, "workload slice:%d", slice); 2596 cfqd->workload_expires = jiffies + slice; 2597} 2598 2599static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2600{ 2601 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2602 struct cfq_group *cfqg; 2603 2604 if (RB_EMPTY_ROOT(&st->rb)) 2605 return NULL; 2606 cfqg = cfq_rb_first_group(st); 2607 update_min_vdisktime(st); 2608 return cfqg; 2609} 2610 2611static void cfq_choose_cfqg(struct cfq_data *cfqd) 2612{ 2613 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2614 2615 cfqd->serving_group = cfqg; 2616 2617 /* Restore the workload type data */ 2618 if (cfqg->saved_wl_slice) { 2619 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice; 2620 cfqd->serving_wl_type = cfqg->saved_wl_type; 2621 cfqd->serving_wl_class = cfqg->saved_wl_class; 2622 } else 2623 cfqd->workload_expires = jiffies - 1; 2624 2625 choose_wl_class_and_type(cfqd, cfqg); 2626} 2627 2628/* 2629 * Select a queue for service. If we have a current active queue, 2630 * check whether to continue servicing it, or retrieve and set a new one. 2631 */ 2632static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2633{ 2634 struct cfq_queue *cfqq, *new_cfqq = NULL; 2635 2636 cfqq = cfqd->active_queue; 2637 if (!cfqq) 2638 goto new_queue; 2639 2640 if (!cfqd->rq_queued) 2641 return NULL; 2642 2643 /* 2644 * We were waiting for group to get backlogged. Expire the queue 2645 */ 2646 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2647 goto expire; 2648 2649 /* 2650 * The active queue has run out of time, expire it and select new. 2651 */ 2652 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2653 /* 2654 * If slice had not expired at the completion of last request 2655 * we might not have turned on wait_busy flag. Don't expire 2656 * the queue yet. Allow the group to get backlogged. 2657 * 2658 * The very fact that we have used the slice, that means we 2659 * have been idling all along on this queue and it should be 2660 * ok to wait for this request to complete. 2661 */ 2662 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2663 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2664 cfqq = NULL; 2665 goto keep_queue; 2666 } else 2667 goto check_group_idle; 2668 } 2669 2670 /* 2671 * The active queue has requests and isn't expired, allow it to 2672 * dispatch. 2673 */ 2674 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2675 goto keep_queue; 2676 2677 /* 2678 * If another queue has a request waiting within our mean seek 2679 * distance, let it run. The expire code will check for close 2680 * cooperators and put the close queue at the front of the service 2681 * tree. If possible, merge the expiring queue with the new cfqq. 2682 */ 2683 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2684 if (new_cfqq) { 2685 if (!cfqq->new_cfqq) 2686 cfq_setup_merge(cfqq, new_cfqq); 2687 goto expire; 2688 } 2689 2690 /* 2691 * No requests pending. If the active queue still has requests in 2692 * flight or is idling for a new request, allow either of these 2693 * conditions to happen (or time out) before selecting a new queue. 2694 */ 2695 if (timer_pending(&cfqd->idle_slice_timer)) { 2696 cfqq = NULL; 2697 goto keep_queue; 2698 } 2699 2700 /* 2701 * This is a deep seek queue, but the device is much faster than 2702 * the queue can deliver, don't idle 2703 **/ 2704 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2705 (cfq_cfqq_slice_new(cfqq) || 2706 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2707 cfq_clear_cfqq_deep(cfqq); 2708 cfq_clear_cfqq_idle_window(cfqq); 2709 } 2710 2711 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2712 cfqq = NULL; 2713 goto keep_queue; 2714 } 2715 2716 /* 2717 * If group idle is enabled and there are requests dispatched from 2718 * this group, wait for requests to complete. 2719 */ 2720check_group_idle: 2721 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && 2722 cfqq->cfqg->dispatched && 2723 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { 2724 cfqq = NULL; 2725 goto keep_queue; 2726 } 2727 2728expire: 2729 cfq_slice_expired(cfqd, 0); 2730new_queue: 2731 /* 2732 * Current queue expired. Check if we have to switch to a new 2733 * service tree 2734 */ 2735 if (!new_cfqq) 2736 cfq_choose_cfqg(cfqd); 2737 2738 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2739keep_queue: 2740 return cfqq; 2741} 2742 2743static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2744{ 2745 int dispatched = 0; 2746 2747 while (cfqq->next_rq) { 2748 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2749 dispatched++; 2750 } 2751 2752 BUG_ON(!list_empty(&cfqq->fifo)); 2753 2754 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2755 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2756 return dispatched; 2757} 2758 2759/* 2760 * Drain our current requests. Used for barriers and when switching 2761 * io schedulers on-the-fly. 2762 */ 2763static int cfq_forced_dispatch(struct cfq_data *cfqd) 2764{ 2765 struct cfq_queue *cfqq; 2766 int dispatched = 0; 2767 2768 /* Expire the timeslice of the current active queue first */ 2769 cfq_slice_expired(cfqd, 0); 2770 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2771 __cfq_set_active_queue(cfqd, cfqq); 2772 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2773 } 2774 2775 BUG_ON(cfqd->busy_queues); 2776 2777 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2778 return dispatched; 2779} 2780 2781static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2782 struct cfq_queue *cfqq) 2783{ 2784 /* the queue hasn't finished any request, can't estimate */ 2785 if (cfq_cfqq_slice_new(cfqq)) 2786 return true; 2787 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2788 cfqq->slice_end)) 2789 return true; 2790 2791 return false; 2792} 2793 2794static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2795{ 2796 unsigned int max_dispatch; 2797 2798 /* 2799 * Drain async requests before we start sync IO 2800 */ 2801 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2802 return false; 2803 2804 /* 2805 * If this is an async queue and we have sync IO in flight, let it wait 2806 */ 2807 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2808 return false; 2809 2810 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2811 if (cfq_class_idle(cfqq)) 2812 max_dispatch = 1; 2813 2814 /* 2815 * Does this cfqq already have too much IO in flight? 2816 */ 2817 if (cfqq->dispatched >= max_dispatch) { 2818 bool promote_sync = false; 2819 /* 2820 * idle queue must always only have a single IO in flight 2821 */ 2822 if (cfq_class_idle(cfqq)) 2823 return false; 2824 2825 /* 2826 * If there is only one sync queue 2827 * we can ignore async queue here and give the sync 2828 * queue no dispatch limit. The reason is a sync queue can 2829 * preempt async queue, limiting the sync queue doesn't make 2830 * sense. This is useful for aiostress test. 2831 */ 2832 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2833 promote_sync = true; 2834 2835 /* 2836 * We have other queues, don't allow more IO from this one 2837 */ 2838 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2839 !promote_sync) 2840 return false; 2841 2842 /* 2843 * Sole queue user, no limit 2844 */ 2845 if (cfqd->busy_queues == 1 || promote_sync) 2846 max_dispatch = -1; 2847 else 2848 /* 2849 * Normally we start throttling cfqq when cfq_quantum/2 2850 * requests have been dispatched. But we can drive 2851 * deeper queue depths at the beginning of slice 2852 * subjected to upper limit of cfq_quantum. 2853 * */ 2854 max_dispatch = cfqd->cfq_quantum; 2855 } 2856 2857 /* 2858 * Async queues must wait a bit before being allowed dispatch. 2859 * We also ramp up the dispatch depth gradually for async IO, 2860 * based on the last sync IO we serviced 2861 */ 2862 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2863 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2864 unsigned int depth; 2865 2866 depth = last_sync / cfqd->cfq_slice[1]; 2867 if (!depth && !cfqq->dispatched) 2868 depth = 1; 2869 if (depth < max_dispatch) 2870 max_dispatch = depth; 2871 } 2872 2873 /* 2874 * If we're below the current max, allow a dispatch 2875 */ 2876 return cfqq->dispatched < max_dispatch; 2877} 2878 2879/* 2880 * Dispatch a request from cfqq, moving them to the request queue 2881 * dispatch list. 2882 */ 2883static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2884{ 2885 struct request *rq; 2886 2887 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2888 2889 if (!cfq_may_dispatch(cfqd, cfqq)) 2890 return false; 2891 2892 /* 2893 * follow expired path, else get first next available 2894 */ 2895 rq = cfq_check_fifo(cfqq); 2896 if (!rq) 2897 rq = cfqq->next_rq; 2898 2899 /* 2900 * insert request into driver dispatch list 2901 */ 2902 cfq_dispatch_insert(cfqd->queue, rq); 2903 2904 if (!cfqd->active_cic) { 2905 struct cfq_io_cq *cic = RQ_CIC(rq); 2906 2907 atomic_long_inc(&cic->icq.ioc->refcount); 2908 cfqd->active_cic = cic; 2909 } 2910 2911 return true; 2912} 2913 2914/* 2915 * Find the cfqq that we need to service and move a request from that to the 2916 * dispatch list 2917 */ 2918static int cfq_dispatch_requests(struct request_queue *q, int force) 2919{ 2920 struct cfq_data *cfqd = q->elevator->elevator_data; 2921 struct cfq_queue *cfqq; 2922 2923 if (!cfqd->busy_queues) 2924 return 0; 2925 2926 if (unlikely(force)) 2927 return cfq_forced_dispatch(cfqd); 2928 2929 cfqq = cfq_select_queue(cfqd); 2930 if (!cfqq) 2931 return 0; 2932 2933 /* 2934 * Dispatch a request from this cfqq, if it is allowed 2935 */ 2936 if (!cfq_dispatch_request(cfqd, cfqq)) 2937 return 0; 2938 2939 cfqq->slice_dispatch++; 2940 cfq_clear_cfqq_must_dispatch(cfqq); 2941 2942 /* 2943 * expire an async queue immediately if it has used up its slice. idle 2944 * queue always expire after 1 dispatch round. 2945 */ 2946 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2947 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2948 cfq_class_idle(cfqq))) { 2949 cfqq->slice_end = jiffies + 1; 2950 cfq_slice_expired(cfqd, 0); 2951 } 2952 2953 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2954 return 1; 2955} 2956 2957/* 2958 * task holds one reference to the queue, dropped when task exits. each rq 2959 * in-flight on this queue also holds a reference, dropped when rq is freed. 2960 * 2961 * Each cfq queue took a reference on the parent group. Drop it now. 2962 * queue lock must be held here. 2963 */ 2964static void cfq_put_queue(struct cfq_queue *cfqq) 2965{ 2966 struct cfq_data *cfqd = cfqq->cfqd; 2967 struct cfq_group *cfqg; 2968 2969 BUG_ON(cfqq->ref <= 0); 2970 2971 cfqq->ref--; 2972 if (cfqq->ref) 2973 return; 2974 2975 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2976 BUG_ON(rb_first(&cfqq->sort_list)); 2977 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2978 cfqg = cfqq->cfqg; 2979 2980 if (unlikely(cfqd->active_queue == cfqq)) { 2981 __cfq_slice_expired(cfqd, cfqq, 0); 2982 cfq_schedule_dispatch(cfqd); 2983 } 2984 2985 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2986 kmem_cache_free(cfq_pool, cfqq); 2987 cfqg_put(cfqg); 2988} 2989 2990static void cfq_put_cooperator(struct cfq_queue *cfqq) 2991{ 2992 struct cfq_queue *__cfqq, *next; 2993 2994 /* 2995 * If this queue was scheduled to merge with another queue, be 2996 * sure to drop the reference taken on that queue (and others in 2997 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2998 */ 2999 __cfqq = cfqq->new_cfqq; 3000 while (__cfqq) { 3001 if (__cfqq == cfqq) { 3002 WARN(1, "cfqq->new_cfqq loop detected\n"); 3003 break; 3004 } 3005 next = __cfqq->new_cfqq; 3006 cfq_put_queue(__cfqq); 3007 __cfqq = next; 3008 } 3009} 3010 3011static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3012{ 3013 if (unlikely(cfqq == cfqd->active_queue)) { 3014 __cfq_slice_expired(cfqd, cfqq, 0); 3015 cfq_schedule_dispatch(cfqd); 3016 } 3017 3018 cfq_put_cooperator(cfqq); 3019 3020 cfq_put_queue(cfqq); 3021} 3022 3023static void cfq_init_icq(struct io_cq *icq) 3024{ 3025 struct cfq_io_cq *cic = icq_to_cic(icq); 3026 3027 cic->ttime.last_end_request = jiffies; 3028} 3029 3030static void cfq_exit_icq(struct io_cq *icq) 3031{ 3032 struct cfq_io_cq *cic = icq_to_cic(icq); 3033 struct cfq_data *cfqd = cic_to_cfqd(cic); 3034 3035 if (cic->cfqq[BLK_RW_ASYNC]) { 3036 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 3037 cic->cfqq[BLK_RW_ASYNC] = NULL; 3038 } 3039 3040 if (cic->cfqq[BLK_RW_SYNC]) { 3041 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 3042 cic->cfqq[BLK_RW_SYNC] = NULL; 3043 } 3044} 3045 3046static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) 3047{ 3048 struct task_struct *tsk = current; 3049 int ioprio_class; 3050 3051 if (!cfq_cfqq_prio_changed(cfqq)) 3052 return; 3053 3054 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3055 switch (ioprio_class) { 3056 default: 3057 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 3058 case IOPRIO_CLASS_NONE: 3059 /* 3060 * no prio set, inherit CPU scheduling settings 3061 */ 3062 cfqq->ioprio = task_nice_ioprio(tsk); 3063 cfqq->ioprio_class = task_nice_ioclass(tsk); 3064 break; 3065 case IOPRIO_CLASS_RT: 3066 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3067 cfqq->ioprio_class = IOPRIO_CLASS_RT; 3068 break; 3069 case IOPRIO_CLASS_BE: 3070 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3071 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3072 break; 3073 case IOPRIO_CLASS_IDLE: 3074 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 3075 cfqq->ioprio = 7; 3076 cfq_clear_cfqq_idle_window(cfqq); 3077 break; 3078 } 3079 3080 /* 3081 * keep track of original prio settings in case we have to temporarily 3082 * elevate the priority of this queue 3083 */ 3084 cfqq->org_ioprio = cfqq->ioprio; 3085 cfq_clear_cfqq_prio_changed(cfqq); 3086} 3087 3088static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio) 3089{ 3090 int ioprio = cic->icq.ioc->ioprio; 3091 struct cfq_data *cfqd = cic_to_cfqd(cic); 3092 struct cfq_queue *cfqq; 3093 3094 /* 3095 * Check whether ioprio has changed. The condition may trigger 3096 * spuriously on a newly created cic but there's no harm. 3097 */ 3098 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio)) 3099 return; 3100 3101 cfqq = cic->cfqq[BLK_RW_ASYNC]; 3102 if (cfqq) { 3103 struct cfq_queue *new_cfqq; 3104 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio, 3105 GFP_ATOMIC); 3106 if (new_cfqq) { 3107 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 3108 cfq_put_queue(cfqq); 3109 } 3110 } 3111 3112 cfqq = cic->cfqq[BLK_RW_SYNC]; 3113 if (cfqq) 3114 cfq_mark_cfqq_prio_changed(cfqq); 3115 3116 cic->ioprio = ioprio; 3117} 3118 3119static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3120 pid_t pid, bool is_sync) 3121{ 3122 RB_CLEAR_NODE(&cfqq->rb_node); 3123 RB_CLEAR_NODE(&cfqq->p_node); 3124 INIT_LIST_HEAD(&cfqq->fifo); 3125 3126 cfqq->ref = 0; 3127 cfqq->cfqd = cfqd; 3128 3129 cfq_mark_cfqq_prio_changed(cfqq); 3130 3131 if (is_sync) { 3132 if (!cfq_class_idle(cfqq)) 3133 cfq_mark_cfqq_idle_window(cfqq); 3134 cfq_mark_cfqq_sync(cfqq); 3135 } 3136 cfqq->pid = pid; 3137} 3138 3139#ifdef CONFIG_CFQ_GROUP_IOSCHED 3140static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) 3141{ 3142 struct cfq_data *cfqd = cic_to_cfqd(cic); 3143 struct cfq_queue *sync_cfqq; 3144 uint64_t id; 3145 3146 rcu_read_lock(); 3147 id = bio_blkcg(bio)->id; 3148 rcu_read_unlock(); 3149 3150 /* 3151 * Check whether blkcg has changed. The condition may trigger 3152 * spuriously on a newly created cic but there's no harm. 3153 */ 3154 if (unlikely(!cfqd) || likely(cic->blkcg_id == id)) 3155 return; 3156 3157 sync_cfqq = cic_to_cfqq(cic, 1); 3158 if (sync_cfqq) { 3159 /* 3160 * Drop reference to sync queue. A new sync queue will be 3161 * assigned in new group upon arrival of a fresh request. 3162 */ 3163 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 3164 cic_set_cfqq(cic, NULL, 1); 3165 cfq_put_queue(sync_cfqq); 3166 } 3167 3168 cic->blkcg_id = id; 3169} 3170#else 3171static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { } 3172#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 3173 3174static struct cfq_queue * 3175cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3176 struct bio *bio, gfp_t gfp_mask) 3177{ 3178 struct blkcg *blkcg; 3179 struct cfq_queue *cfqq, *new_cfqq = NULL; 3180 struct cfq_group *cfqg; 3181 3182retry: 3183 rcu_read_lock(); 3184 3185 blkcg = bio_blkcg(bio); 3186 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg); 3187 cfqq = cic_to_cfqq(cic, is_sync); 3188 3189 /* 3190 * Always try a new alloc if we fell back to the OOM cfqq 3191 * originally, since it should just be a temporary situation. 3192 */ 3193 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3194 cfqq = NULL; 3195 if (new_cfqq) { 3196 cfqq = new_cfqq; 3197 new_cfqq = NULL; 3198 } else if (gfp_mask & __GFP_WAIT) { 3199 rcu_read_unlock(); 3200 spin_unlock_irq(cfqd->queue->queue_lock); 3201 new_cfqq = kmem_cache_alloc_node(cfq_pool, 3202 gfp_mask | __GFP_ZERO, 3203 cfqd->queue->node); 3204 spin_lock_irq(cfqd->queue->queue_lock); 3205 if (new_cfqq) 3206 goto retry; 3207 } else { 3208 cfqq = kmem_cache_alloc_node(cfq_pool, 3209 gfp_mask | __GFP_ZERO, 3210 cfqd->queue->node); 3211 } 3212 3213 if (cfqq) { 3214 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3215 cfq_init_prio_data(cfqq, cic); 3216 cfq_link_cfqq_cfqg(cfqq, cfqg); 3217 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3218 } else 3219 cfqq = &cfqd->oom_cfqq; 3220 } 3221 3222 if (new_cfqq) 3223 kmem_cache_free(cfq_pool, new_cfqq); 3224 3225 rcu_read_unlock(); 3226 return cfqq; 3227} 3228 3229static struct cfq_queue ** 3230cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3231{ 3232 switch (ioprio_class) { 3233 case IOPRIO_CLASS_RT: 3234 return &cfqd->async_cfqq[0][ioprio]; 3235 case IOPRIO_CLASS_NONE: 3236 ioprio = IOPRIO_NORM; 3237 /* fall through */ 3238 case IOPRIO_CLASS_BE: 3239 return &cfqd->async_cfqq[1][ioprio]; 3240 case IOPRIO_CLASS_IDLE: 3241 return &cfqd->async_idle_cfqq; 3242 default: 3243 BUG(); 3244 } 3245} 3246 3247static struct cfq_queue * 3248cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3249 struct bio *bio, gfp_t gfp_mask) 3250{ 3251 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3252 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3253 struct cfq_queue **async_cfqq = NULL; 3254 struct cfq_queue *cfqq = NULL; 3255 3256 if (!is_sync) { 3257 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3258 cfqq = *async_cfqq; 3259 } 3260 3261 if (!cfqq) 3262 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask); 3263 3264 /* 3265 * pin the queue now that it's allocated, scheduler exit will prune it 3266 */ 3267 if (!is_sync && !(*async_cfqq)) { 3268 cfqq->ref++; 3269 *async_cfqq = cfqq; 3270 } 3271 3272 cfqq->ref++; 3273 return cfqq; 3274} 3275 3276static void 3277__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) 3278{ 3279 unsigned long elapsed = jiffies - ttime->last_end_request; 3280 elapsed = min(elapsed, 2UL * slice_idle); 3281 3282 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; 3283 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; 3284 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; 3285} 3286 3287static void 3288cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3289 struct cfq_io_cq *cic) 3290{ 3291 if (cfq_cfqq_sync(cfqq)) { 3292 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); 3293 __cfq_update_io_thinktime(&cfqq->service_tree->ttime, 3294 cfqd->cfq_slice_idle); 3295 } 3296#ifdef CONFIG_CFQ_GROUP_IOSCHED 3297 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); 3298#endif 3299} 3300 3301static void 3302cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3303 struct request *rq) 3304{ 3305 sector_t sdist = 0; 3306 sector_t n_sec = blk_rq_sectors(rq); 3307 if (cfqq->last_request_pos) { 3308 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3309 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3310 else 3311 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3312 } 3313 3314 cfqq->seek_history <<= 1; 3315 if (blk_queue_nonrot(cfqd->queue)) 3316 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3317 else 3318 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3319} 3320 3321/* 3322 * Disable idle window if the process thinks too long or seeks so much that 3323 * it doesn't matter 3324 */ 3325static void 3326cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3327 struct cfq_io_cq *cic) 3328{ 3329 int old_idle, enable_idle; 3330 3331 /* 3332 * Don't idle for async or idle io prio class 3333 */ 3334 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3335 return; 3336 3337 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3338 3339 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3340 cfq_mark_cfqq_deep(cfqq); 3341 3342 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3343 enable_idle = 0; 3344 else if (!atomic_read(&cic->icq.ioc->active_ref) || 3345 !cfqd->cfq_slice_idle || 3346 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3347 enable_idle = 0; 3348 else if (sample_valid(cic->ttime.ttime_samples)) { 3349 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) 3350 enable_idle = 0; 3351 else 3352 enable_idle = 1; 3353 } 3354 3355 if (old_idle != enable_idle) { 3356 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3357 if (enable_idle) 3358 cfq_mark_cfqq_idle_window(cfqq); 3359 else 3360 cfq_clear_cfqq_idle_window(cfqq); 3361 } 3362} 3363 3364/* 3365 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3366 * no or if we aren't sure, a 1 will cause a preempt. 3367 */ 3368static bool 3369cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3370 struct request *rq) 3371{ 3372 struct cfq_queue *cfqq; 3373 3374 cfqq = cfqd->active_queue; 3375 if (!cfqq) 3376 return false; 3377 3378 if (cfq_class_idle(new_cfqq)) 3379 return false; 3380 3381 if (cfq_class_idle(cfqq)) 3382 return true; 3383 3384 /* 3385 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3386 */ 3387 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3388 return false; 3389 3390 /* 3391 * if the new request is sync, but the currently running queue is 3392 * not, let the sync request have priority. 3393 */ 3394 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3395 return true; 3396 3397 if (new_cfqq->cfqg != cfqq->cfqg) 3398 return false; 3399 3400 if (cfq_slice_used(cfqq)) 3401 return true; 3402 3403 /* Allow preemption only if we are idling on sync-noidle tree */ 3404 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD && 3405 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3406 new_cfqq->service_tree->count == 2 && 3407 RB_EMPTY_ROOT(&cfqq->sort_list)) 3408 return true; 3409 3410 /* 3411 * So both queues are sync. Let the new request get disk time if 3412 * it's a metadata request and the current queue is doing regular IO. 3413 */ 3414 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) 3415 return true; 3416 3417 /* 3418 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3419 */ 3420 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3421 return true; 3422 3423 /* An idle queue should not be idle now for some reason */ 3424 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3425 return true; 3426 3427 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3428 return false; 3429 3430 /* 3431 * if this request is as-good as one we would expect from the 3432 * current cfqq, let it preempt 3433 */ 3434 if (cfq_rq_close(cfqd, cfqq, rq)) 3435 return true; 3436 3437 return false; 3438} 3439 3440/* 3441 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3442 * let it have half of its nominal slice. 3443 */ 3444static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3445{ 3446 enum wl_type_t old_type = cfqq_type(cfqd->active_queue); 3447 3448 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3449 cfq_slice_expired(cfqd, 1); 3450 3451 /* 3452 * workload type is changed, don't save slice, otherwise preempt 3453 * doesn't happen 3454 */ 3455 if (old_type != cfqq_type(cfqq)) 3456 cfqq->cfqg->saved_wl_slice = 0; 3457 3458 /* 3459 * Put the new queue at the front of the of the current list, 3460 * so we know that it will be selected next. 3461 */ 3462 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3463 3464 cfq_service_tree_add(cfqd, cfqq, 1); 3465 3466 cfqq->slice_end = 0; 3467 cfq_mark_cfqq_slice_new(cfqq); 3468} 3469 3470/* 3471 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3472 * something we should do about it 3473 */ 3474static void 3475cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3476 struct request *rq) 3477{ 3478 struct cfq_io_cq *cic = RQ_CIC(rq); 3479 3480 cfqd->rq_queued++; 3481 if (rq->cmd_flags & REQ_PRIO) 3482 cfqq->prio_pending++; 3483 3484 cfq_update_io_thinktime(cfqd, cfqq, cic); 3485 cfq_update_io_seektime(cfqd, cfqq, rq); 3486 cfq_update_idle_window(cfqd, cfqq, cic); 3487 3488 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3489 3490 if (cfqq == cfqd->active_queue) { 3491 /* 3492 * Remember that we saw a request from this process, but 3493 * don't start queuing just yet. Otherwise we risk seeing lots 3494 * of tiny requests, because we disrupt the normal plugging 3495 * and merging. If the request is already larger than a single 3496 * page, let it rip immediately. For that case we assume that 3497 * merging is already done. Ditto for a busy system that 3498 * has other work pending, don't risk delaying until the 3499 * idle timer unplug to continue working. 3500 */ 3501 if (cfq_cfqq_wait_request(cfqq)) { 3502 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3503 cfqd->busy_queues > 1) { 3504 cfq_del_timer(cfqd, cfqq); 3505 cfq_clear_cfqq_wait_request(cfqq); 3506 __blk_run_queue(cfqd->queue); 3507 } else { 3508 cfqg_stats_update_idle_time(cfqq->cfqg); 3509 cfq_mark_cfqq_must_dispatch(cfqq); 3510 } 3511 } 3512 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3513 /* 3514 * not the active queue - expire current slice if it is 3515 * idle and has expired it's mean thinktime or this new queue 3516 * has some old slice time left and is of higher priority or 3517 * this new queue is RT and the current one is BE 3518 */ 3519 cfq_preempt_queue(cfqd, cfqq); 3520 __blk_run_queue(cfqd->queue); 3521 } 3522} 3523 3524static void cfq_insert_request(struct request_queue *q, struct request *rq) 3525{ 3526 struct cfq_data *cfqd = q->elevator->elevator_data; 3527 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3528 3529 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3530 cfq_init_prio_data(cfqq, RQ_CIC(rq)); 3531 3532 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3533 list_add_tail(&rq->queuelist, &cfqq->fifo); 3534 cfq_add_rq_rb(rq); 3535 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group, 3536 rq->cmd_flags); 3537 cfq_rq_enqueued(cfqd, cfqq, rq); 3538} 3539 3540/* 3541 * Update hw_tag based on peak queue depth over 50 samples under 3542 * sufficient load. 3543 */ 3544static void cfq_update_hw_tag(struct cfq_data *cfqd) 3545{ 3546 struct cfq_queue *cfqq = cfqd->active_queue; 3547 3548 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3549 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3550 3551 if (cfqd->hw_tag == 1) 3552 return; 3553 3554 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3555 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3556 return; 3557 3558 /* 3559 * If active queue hasn't enough requests and can idle, cfq might not 3560 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3561 * case 3562 */ 3563 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3564 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3565 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3566 return; 3567 3568 if (cfqd->hw_tag_samples++ < 50) 3569 return; 3570 3571 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3572 cfqd->hw_tag = 1; 3573 else 3574 cfqd->hw_tag = 0; 3575} 3576 3577static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3578{ 3579 struct cfq_io_cq *cic = cfqd->active_cic; 3580 3581 /* If the queue already has requests, don't wait */ 3582 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3583 return false; 3584 3585 /* If there are other queues in the group, don't wait */ 3586 if (cfqq->cfqg->nr_cfqq > 1) 3587 return false; 3588 3589 /* the only queue in the group, but think time is big */ 3590 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) 3591 return false; 3592 3593 if (cfq_slice_used(cfqq)) 3594 return true; 3595 3596 /* if slice left is less than think time, wait busy */ 3597 if (cic && sample_valid(cic->ttime.ttime_samples) 3598 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) 3599 return true; 3600 3601 /* 3602 * If think times is less than a jiffy than ttime_mean=0 and above 3603 * will not be true. It might happen that slice has not expired yet 3604 * but will expire soon (4-5 ns) during select_queue(). To cover the 3605 * case where think time is less than a jiffy, mark the queue wait 3606 * busy if only 1 jiffy is left in the slice. 3607 */ 3608 if (cfqq->slice_end - jiffies == 1) 3609 return true; 3610 3611 return false; 3612} 3613 3614static void cfq_completed_request(struct request_queue *q, struct request *rq) 3615{ 3616 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3617 struct cfq_data *cfqd = cfqq->cfqd; 3618 const int sync = rq_is_sync(rq); 3619 unsigned long now; 3620 3621 now = jiffies; 3622 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3623 !!(rq->cmd_flags & REQ_NOIDLE)); 3624 3625 cfq_update_hw_tag(cfqd); 3626 3627 WARN_ON(!cfqd->rq_in_driver); 3628 WARN_ON(!cfqq->dispatched); 3629 cfqd->rq_in_driver--; 3630 cfqq->dispatched--; 3631 (RQ_CFQG(rq))->dispatched--; 3632 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq), 3633 rq_io_start_time_ns(rq), rq->cmd_flags); 3634 3635 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3636 3637 if (sync) { 3638 struct cfq_rb_root *st; 3639 3640 RQ_CIC(rq)->ttime.last_end_request = now; 3641 3642 if (cfq_cfqq_on_rr(cfqq)) 3643 st = cfqq->service_tree; 3644 else 3645 st = st_for(cfqq->cfqg, cfqq_class(cfqq), 3646 cfqq_type(cfqq)); 3647 3648 st->ttime.last_end_request = now; 3649 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3650 cfqd->last_delayed_sync = now; 3651 } 3652 3653#ifdef CONFIG_CFQ_GROUP_IOSCHED 3654 cfqq->cfqg->ttime.last_end_request = now; 3655#endif 3656 3657 /* 3658 * If this is the active queue, check if it needs to be expired, 3659 * or if we want to idle in case it has no pending requests. 3660 */ 3661 if (cfqd->active_queue == cfqq) { 3662 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3663 3664 if (cfq_cfqq_slice_new(cfqq)) { 3665 cfq_set_prio_slice(cfqd, cfqq); 3666 cfq_clear_cfqq_slice_new(cfqq); 3667 } 3668 3669 /* 3670 * Should we wait for next request to come in before we expire 3671 * the queue. 3672 */ 3673 if (cfq_should_wait_busy(cfqd, cfqq)) { 3674 unsigned long extend_sl = cfqd->cfq_slice_idle; 3675 if (!cfqd->cfq_slice_idle) 3676 extend_sl = cfqd->cfq_group_idle; 3677 cfqq->slice_end = jiffies + extend_sl; 3678 cfq_mark_cfqq_wait_busy(cfqq); 3679 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3680 } 3681 3682 /* 3683 * Idling is not enabled on: 3684 * - expired queues 3685 * - idle-priority queues 3686 * - async queues 3687 * - queues with still some requests queued 3688 * - when there is a close cooperator 3689 */ 3690 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3691 cfq_slice_expired(cfqd, 1); 3692 else if (sync && cfqq_empty && 3693 !cfq_close_cooperator(cfqd, cfqq)) { 3694 cfq_arm_slice_timer(cfqd); 3695 } 3696 } 3697 3698 if (!cfqd->rq_in_driver) 3699 cfq_schedule_dispatch(cfqd); 3700} 3701 3702static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3703{ 3704 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3705 cfq_mark_cfqq_must_alloc_slice(cfqq); 3706 return ELV_MQUEUE_MUST; 3707 } 3708 3709 return ELV_MQUEUE_MAY; 3710} 3711 3712static int cfq_may_queue(struct request_queue *q, int rw) 3713{ 3714 struct cfq_data *cfqd = q->elevator->elevator_data; 3715 struct task_struct *tsk = current; 3716 struct cfq_io_cq *cic; 3717 struct cfq_queue *cfqq; 3718 3719 /* 3720 * don't force setup of a queue from here, as a call to may_queue 3721 * does not necessarily imply that a request actually will be queued. 3722 * so just lookup a possibly existing queue, or return 'may queue' 3723 * if that fails 3724 */ 3725 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3726 if (!cic) 3727 return ELV_MQUEUE_MAY; 3728 3729 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3730 if (cfqq) { 3731 cfq_init_prio_data(cfqq, cic); 3732 3733 return __cfq_may_queue(cfqq); 3734 } 3735 3736 return ELV_MQUEUE_MAY; 3737} 3738 3739/* 3740 * queue lock held here 3741 */ 3742static void cfq_put_request(struct request *rq) 3743{ 3744 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3745 3746 if (cfqq) { 3747 const int rw = rq_data_dir(rq); 3748 3749 BUG_ON(!cfqq->allocated[rw]); 3750 cfqq->allocated[rw]--; 3751 3752 /* Put down rq reference on cfqg */ 3753 cfqg_put(RQ_CFQG(rq)); 3754 rq->elv.priv[0] = NULL; 3755 rq->elv.priv[1] = NULL; 3756 3757 cfq_put_queue(cfqq); 3758 } 3759} 3760 3761static struct cfq_queue * 3762cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic, 3763 struct cfq_queue *cfqq) 3764{ 3765 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3766 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3767 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3768 cfq_put_queue(cfqq); 3769 return cic_to_cfqq(cic, 1); 3770} 3771 3772/* 3773 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3774 * was the last process referring to said cfqq. 3775 */ 3776static struct cfq_queue * 3777split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq) 3778{ 3779 if (cfqq_process_refs(cfqq) == 1) { 3780 cfqq->pid = current->pid; 3781 cfq_clear_cfqq_coop(cfqq); 3782 cfq_clear_cfqq_split_coop(cfqq); 3783 return cfqq; 3784 } 3785 3786 cic_set_cfqq(cic, NULL, 1); 3787 3788 cfq_put_cooperator(cfqq); 3789 3790 cfq_put_queue(cfqq); 3791 return NULL; 3792} 3793/* 3794 * Allocate cfq data structures associated with this request. 3795 */ 3796static int 3797cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, 3798 gfp_t gfp_mask) 3799{ 3800 struct cfq_data *cfqd = q->elevator->elevator_data; 3801 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq); 3802 const int rw = rq_data_dir(rq); 3803 const bool is_sync = rq_is_sync(rq); 3804 struct cfq_queue *cfqq; 3805 3806 might_sleep_if(gfp_mask & __GFP_WAIT); 3807 3808 spin_lock_irq(q->queue_lock); 3809 3810 check_ioprio_changed(cic, bio); 3811 check_blkcg_changed(cic, bio); 3812new_queue: 3813 cfqq = cic_to_cfqq(cic, is_sync); 3814 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3815 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask); 3816 cic_set_cfqq(cic, cfqq, is_sync); 3817 } else { 3818 /* 3819 * If the queue was seeky for too long, break it apart. 3820 */ 3821 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3822 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3823 cfqq = split_cfqq(cic, cfqq); 3824 if (!cfqq) 3825 goto new_queue; 3826 } 3827 3828 /* 3829 * Check to see if this queue is scheduled to merge with 3830 * another, closely cooperating queue. The merging of 3831 * queues happens here as it must be done in process context. 3832 * The reference on new_cfqq was taken in merge_cfqqs. 3833 */ 3834 if (cfqq->new_cfqq) 3835 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3836 } 3837 3838 cfqq->allocated[rw]++; 3839 3840 cfqq->ref++; 3841 cfqg_get(cfqq->cfqg); 3842 rq->elv.priv[0] = cfqq; 3843 rq->elv.priv[1] = cfqq->cfqg; 3844 spin_unlock_irq(q->queue_lock); 3845 return 0; 3846} 3847 3848static void cfq_kick_queue(struct work_struct *work) 3849{ 3850 struct cfq_data *cfqd = 3851 container_of(work, struct cfq_data, unplug_work); 3852 struct request_queue *q = cfqd->queue; 3853 3854 spin_lock_irq(q->queue_lock); 3855 __blk_run_queue(cfqd->queue); 3856 spin_unlock_irq(q->queue_lock); 3857} 3858 3859/* 3860 * Timer running if the active_queue is currently idling inside its time slice 3861 */ 3862static void cfq_idle_slice_timer(unsigned long data) 3863{ 3864 struct cfq_data *cfqd = (struct cfq_data *) data; 3865 struct cfq_queue *cfqq; 3866 unsigned long flags; 3867 int timed_out = 1; 3868 3869 cfq_log(cfqd, "idle timer fired"); 3870 3871 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3872 3873 cfqq = cfqd->active_queue; 3874 if (cfqq) { 3875 timed_out = 0; 3876 3877 /* 3878 * We saw a request before the queue expired, let it through 3879 */ 3880 if (cfq_cfqq_must_dispatch(cfqq)) 3881 goto out_kick; 3882 3883 /* 3884 * expired 3885 */ 3886 if (cfq_slice_used(cfqq)) 3887 goto expire; 3888 3889 /* 3890 * only expire and reinvoke request handler, if there are 3891 * other queues with pending requests 3892 */ 3893 if (!cfqd->busy_queues) 3894 goto out_cont; 3895 3896 /* 3897 * not expired and it has a request pending, let it dispatch 3898 */ 3899 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3900 goto out_kick; 3901 3902 /* 3903 * Queue depth flag is reset only when the idle didn't succeed 3904 */ 3905 cfq_clear_cfqq_deep(cfqq); 3906 } 3907expire: 3908 cfq_slice_expired(cfqd, timed_out); 3909out_kick: 3910 cfq_schedule_dispatch(cfqd); 3911out_cont: 3912 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3913} 3914 3915static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3916{ 3917 del_timer_sync(&cfqd->idle_slice_timer); 3918 cancel_work_sync(&cfqd->unplug_work); 3919} 3920 3921static void cfq_put_async_queues(struct cfq_data *cfqd) 3922{ 3923 int i; 3924 3925 for (i = 0; i < IOPRIO_BE_NR; i++) { 3926 if (cfqd->async_cfqq[0][i]) 3927 cfq_put_queue(cfqd->async_cfqq[0][i]); 3928 if (cfqd->async_cfqq[1][i]) 3929 cfq_put_queue(cfqd->async_cfqq[1][i]); 3930 } 3931 3932 if (cfqd->async_idle_cfqq) 3933 cfq_put_queue(cfqd->async_idle_cfqq); 3934} 3935 3936static void cfq_exit_queue(struct elevator_queue *e) 3937{ 3938 struct cfq_data *cfqd = e->elevator_data; 3939 struct request_queue *q = cfqd->queue; 3940 3941 cfq_shutdown_timer_wq(cfqd); 3942 3943 spin_lock_irq(q->queue_lock); 3944 3945 if (cfqd->active_queue) 3946 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3947 3948 cfq_put_async_queues(cfqd); 3949 3950 spin_unlock_irq(q->queue_lock); 3951 3952 cfq_shutdown_timer_wq(cfqd); 3953 3954#ifdef CONFIG_CFQ_GROUP_IOSCHED 3955 blkcg_deactivate_policy(q, &blkcg_policy_cfq); 3956#else 3957 kfree(cfqd->root_group); 3958#endif 3959 kfree(cfqd); 3960} 3961 3962static int cfq_init_queue(struct request_queue *q) 3963{ 3964 struct cfq_data *cfqd; 3965 struct blkcg_gq *blkg __maybe_unused; 3966 int i, ret; 3967 3968 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3969 if (!cfqd) 3970 return -ENOMEM; 3971 3972 cfqd->queue = q; 3973 q->elevator->elevator_data = cfqd; 3974 3975 /* Init root service tree */ 3976 cfqd->grp_service_tree = CFQ_RB_ROOT; 3977 3978 /* Init root group and prefer root group over other groups by default */ 3979#ifdef CONFIG_CFQ_GROUP_IOSCHED 3980 ret = blkcg_activate_policy(q, &blkcg_policy_cfq); 3981 if (ret) 3982 goto out_free; 3983 3984 cfqd->root_group = blkg_to_cfqg(q->root_blkg); 3985#else 3986 ret = -ENOMEM; 3987 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group), 3988 GFP_KERNEL, cfqd->queue->node); 3989 if (!cfqd->root_group) 3990 goto out_free; 3991 3992 cfq_init_cfqg_base(cfqd->root_group); 3993#endif 3994 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT; 3995 3996 /* 3997 * Not strictly needed (since RB_ROOT just clears the node and we 3998 * zeroed cfqd on alloc), but better be safe in case someone decides 3999 * to add magic to the rb code 4000 */ 4001 for (i = 0; i < CFQ_PRIO_LISTS; i++) 4002 cfqd->prio_trees[i] = RB_ROOT; 4003 4004 /* 4005 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 4006 * Grab a permanent reference to it, so that the normal code flow 4007 * will not attempt to free it. oom_cfqq is linked to root_group 4008 * but shouldn't hold a reference as it'll never be unlinked. Lose 4009 * the reference from linking right away. 4010 */ 4011 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 4012 cfqd->oom_cfqq.ref++; 4013 4014 spin_lock_irq(q->queue_lock); 4015 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group); 4016 cfqg_put(cfqd->root_group); 4017 spin_unlock_irq(q->queue_lock); 4018 4019 init_timer(&cfqd->idle_slice_timer); 4020 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4021 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4022 4023 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4024 4025 cfqd->cfq_quantum = cfq_quantum; 4026 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4027 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4028 cfqd->cfq_back_max = cfq_back_max; 4029 cfqd->cfq_back_penalty = cfq_back_penalty; 4030 cfqd->cfq_slice[0] = cfq_slice_async; 4031 cfqd->cfq_slice[1] = cfq_slice_sync; 4032 cfqd->cfq_target_latency = cfq_target_latency; 4033 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4034 cfqd->cfq_slice_idle = cfq_slice_idle; 4035 cfqd->cfq_group_idle = cfq_group_idle; 4036 cfqd->cfq_latency = 1; 4037 cfqd->hw_tag = -1; 4038 /* 4039 * we optimistically start assuming sync ops weren't delayed in last 4040 * second, in order to have larger depth for async operations. 4041 */ 4042 cfqd->last_delayed_sync = jiffies - HZ; 4043 return 0; 4044 4045out_free: 4046 kfree(cfqd); 4047 return ret; 4048} 4049 4050/* 4051 * sysfs parts below --> 4052 */ 4053static ssize_t 4054cfq_var_show(unsigned int var, char *page) 4055{ 4056 return sprintf(page, "%d\n", var); 4057} 4058 4059static ssize_t 4060cfq_var_store(unsigned int *var, const char *page, size_t count) 4061{ 4062 char *p = (char *) page; 4063 4064 *var = simple_strtoul(p, &p, 10); 4065 return count; 4066} 4067 4068#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4069static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4070{ \ 4071 struct cfq_data *cfqd = e->elevator_data; \ 4072 unsigned int __data = __VAR; \ 4073 if (__CONV) \ 4074 __data = jiffies_to_msecs(__data); \ 4075 return cfq_var_show(__data, (page)); \ 4076} 4077SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4078SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4079SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4080SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4081SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4082SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4083SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4084SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4085SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4086SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4087SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4088SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1); 4089#undef SHOW_FUNCTION 4090 4091#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4092static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4093{ \ 4094 struct cfq_data *cfqd = e->elevator_data; \ 4095 unsigned int __data; \ 4096 int ret = cfq_var_store(&__data, (page), count); \ 4097 if (__data < (MIN)) \ 4098 __data = (MIN); \ 4099 else if (__data > (MAX)) \ 4100 __data = (MAX); \ 4101 if (__CONV) \ 4102 *(__PTR) = msecs_to_jiffies(__data); \ 4103 else \ 4104 *(__PTR) = __data; \ 4105 return ret; \ 4106} 4107STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4108STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4109 UINT_MAX, 1); 4110STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4111 UINT_MAX, 1); 4112STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4113STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4114 UINT_MAX, 0); 4115STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4116STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4117STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4118STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4119STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4120 UINT_MAX, 0); 4121STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4122STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1); 4123#undef STORE_FUNCTION 4124 4125#define CFQ_ATTR(name) \ 4126 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4127 4128static struct elv_fs_entry cfq_attrs[] = { 4129 CFQ_ATTR(quantum), 4130 CFQ_ATTR(fifo_expire_sync), 4131 CFQ_ATTR(fifo_expire_async), 4132 CFQ_ATTR(back_seek_max), 4133 CFQ_ATTR(back_seek_penalty), 4134 CFQ_ATTR(slice_sync), 4135 CFQ_ATTR(slice_async), 4136 CFQ_ATTR(slice_async_rq), 4137 CFQ_ATTR(slice_idle), 4138 CFQ_ATTR(group_idle), 4139 CFQ_ATTR(low_latency), 4140 CFQ_ATTR(target_latency), 4141 __ATTR_NULL 4142}; 4143 4144static struct elevator_type iosched_cfq = { 4145 .ops = { 4146 .elevator_merge_fn = cfq_merge, 4147 .elevator_merged_fn = cfq_merged_request, 4148 .elevator_merge_req_fn = cfq_merged_requests, 4149 .elevator_allow_merge_fn = cfq_allow_merge, 4150 .elevator_bio_merged_fn = cfq_bio_merged, 4151 .elevator_dispatch_fn = cfq_dispatch_requests, 4152 .elevator_add_req_fn = cfq_insert_request, 4153 .elevator_activate_req_fn = cfq_activate_request, 4154 .elevator_deactivate_req_fn = cfq_deactivate_request, 4155 .elevator_completed_req_fn = cfq_completed_request, 4156 .elevator_former_req_fn = elv_rb_former_request, 4157 .elevator_latter_req_fn = elv_rb_latter_request, 4158 .elevator_init_icq_fn = cfq_init_icq, 4159 .elevator_exit_icq_fn = cfq_exit_icq, 4160 .elevator_set_req_fn = cfq_set_request, 4161 .elevator_put_req_fn = cfq_put_request, 4162 .elevator_may_queue_fn = cfq_may_queue, 4163 .elevator_init_fn = cfq_init_queue, 4164 .elevator_exit_fn = cfq_exit_queue, 4165 }, 4166 .icq_size = sizeof(struct cfq_io_cq), 4167 .icq_align = __alignof__(struct cfq_io_cq), 4168 .elevator_attrs = cfq_attrs, 4169 .elevator_name = "cfq", 4170 .elevator_owner = THIS_MODULE, 4171}; 4172 4173#ifdef CONFIG_CFQ_GROUP_IOSCHED 4174static struct blkcg_policy blkcg_policy_cfq = { 4175 .pd_size = sizeof(struct cfq_group), 4176 .cftypes = cfq_blkcg_files, 4177 4178 .pd_init_fn = cfq_pd_init, 4179 .pd_reset_stats_fn = cfq_pd_reset_stats, 4180}; 4181#endif 4182 4183static int __init cfq_init(void) 4184{ 4185 int ret; 4186 4187 /* 4188 * could be 0 on HZ < 1000 setups 4189 */ 4190 if (!cfq_slice_async) 4191 cfq_slice_async = 1; 4192 if (!cfq_slice_idle) 4193 cfq_slice_idle = 1; 4194 4195#ifdef CONFIG_CFQ_GROUP_IOSCHED 4196 if (!cfq_group_idle) 4197 cfq_group_idle = 1; 4198 4199 ret = blkcg_policy_register(&blkcg_policy_cfq); 4200 if (ret) 4201 return ret; 4202#else 4203 cfq_group_idle = 0; 4204#endif 4205 4206 ret = -ENOMEM; 4207 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4208 if (!cfq_pool) 4209 goto err_pol_unreg; 4210 4211 ret = elv_register(&iosched_cfq); 4212 if (ret) 4213 goto err_free_pool; 4214 4215 return 0; 4216 4217err_free_pool: 4218 kmem_cache_destroy(cfq_pool); 4219err_pol_unreg: 4220#ifdef CONFIG_CFQ_GROUP_IOSCHED 4221 blkcg_policy_unregister(&blkcg_policy_cfq); 4222#endif 4223 return ret; 4224} 4225 4226static void __exit cfq_exit(void) 4227{ 4228#ifdef CONFIG_CFQ_GROUP_IOSCHED 4229 blkcg_policy_unregister(&blkcg_policy_cfq); 4230#endif 4231 elv_unregister(&iosched_cfq); 4232 kmem_cache_destroy(cfq_pool); 4233} 4234 4235module_init(cfq_init); 4236module_exit(cfq_exit); 4237 4238MODULE_AUTHOR("Jens Axboe"); 4239MODULE_LICENSE("GPL"); 4240MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4241