cfq-iosched.c revision 1d3650f713e7f6392b02fde450c5bae40291e65b
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; 226 227 /* 228 * The number of active cfqgs and sum of their weights under this 229 * cfqg. This covers this cfqg's leaf_weight and all children's 230 * weights, but does not cover weights of further descendants. 231 * 232 * If a cfqg is on the service tree, it's active. An active cfqg 233 * also activates its parent and contributes to the children_weight 234 * of the parent. 235 */ 236 int nr_active; 237 unsigned int children_weight; 238 239 /* 240 * vfraction is the fraction of vdisktime that the tasks in this 241 * cfqg are entitled to. This is determined by compounding the 242 * ratios walking up from this cfqg to the root. 243 * 244 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all 245 * vfractions on a service tree is approximately 1. The sum may 246 * deviate a bit due to rounding errors and fluctuations caused by 247 * cfqgs entering and leaving the service tree. 248 */ 249 unsigned int vfraction; 250 251 /* 252 * There are two weights - (internal) weight is the weight of this 253 * cfqg against the sibling cfqgs. leaf_weight is the wight of 254 * this cfqg against the child cfqgs. For the root cfqg, both 255 * weights are kept in sync for backward compatibility. 256 */ 257 unsigned int weight; 258 unsigned int new_weight; 259 unsigned int dev_weight; 260 261 unsigned int leaf_weight; 262 unsigned int new_leaf_weight; 263 unsigned int dev_leaf_weight; 264 265 /* number of cfqq currently on this group */ 266 int nr_cfqq; 267 268 /* 269 * Per group busy queues average. Useful for workload slice calc. We 270 * create the array for each prio class but at run time it is used 271 * only for RT and BE class and slot for IDLE class remains unused. 272 * This is primarily done to avoid confusion and a gcc warning. 273 */ 274 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 275 /* 276 * rr lists of queues with requests. We maintain service trees for 277 * RT and BE classes. These trees are subdivided in subclasses 278 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 279 * class there is no subclassification and all the cfq queues go on 280 * a single tree service_tree_idle. 281 * Counts are embedded in the cfq_rb_root 282 */ 283 struct cfq_rb_root service_trees[2][3]; 284 struct cfq_rb_root service_tree_idle; 285 286 unsigned long saved_wl_slice; 287 enum wl_type_t saved_wl_type; 288 enum wl_class_t saved_wl_class; 289 290 /* number of requests that are on the dispatch list or inside driver */ 291 int dispatched; 292 struct cfq_ttime ttime; 293 struct cfqg_stats stats; 294}; 295 296struct cfq_io_cq { 297 struct io_cq icq; /* must be the first member */ 298 struct cfq_queue *cfqq[2]; 299 struct cfq_ttime ttime; 300 int ioprio; /* the current ioprio */ 301#ifdef CONFIG_CFQ_GROUP_IOSCHED 302 uint64_t blkcg_id; /* the current blkcg ID */ 303#endif 304}; 305 306/* 307 * Per block device queue structure 308 */ 309struct cfq_data { 310 struct request_queue *queue; 311 /* Root service tree for cfq_groups */ 312 struct cfq_rb_root grp_service_tree; 313 struct cfq_group *root_group; 314 315 /* 316 * The priority currently being served 317 */ 318 enum wl_class_t serving_wl_class; 319 enum wl_type_t serving_wl_type; 320 unsigned long workload_expires; 321 struct cfq_group *serving_group; 322 323 /* 324 * Each priority tree is sorted by next_request position. These 325 * trees are used when determining if two or more queues are 326 * interleaving requests (see cfq_close_cooperator). 327 */ 328 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 329 330 unsigned int busy_queues; 331 unsigned int busy_sync_queues; 332 333 int rq_in_driver; 334 int rq_in_flight[2]; 335 336 /* 337 * queue-depth detection 338 */ 339 int rq_queued; 340 int hw_tag; 341 /* 342 * hw_tag can be 343 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 344 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 345 * 0 => no NCQ 346 */ 347 int hw_tag_est_depth; 348 unsigned int hw_tag_samples; 349 350 /* 351 * idle window management 352 */ 353 struct timer_list idle_slice_timer; 354 struct work_struct unplug_work; 355 356 struct cfq_queue *active_queue; 357 struct cfq_io_cq *active_cic; 358 359 /* 360 * async queue for each priority case 361 */ 362 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 363 struct cfq_queue *async_idle_cfqq; 364 365 sector_t last_position; 366 367 /* 368 * tunables, see top of file 369 */ 370 unsigned int cfq_quantum; 371 unsigned int cfq_fifo_expire[2]; 372 unsigned int cfq_back_penalty; 373 unsigned int cfq_back_max; 374 unsigned int cfq_slice[2]; 375 unsigned int cfq_slice_async_rq; 376 unsigned int cfq_slice_idle; 377 unsigned int cfq_group_idle; 378 unsigned int cfq_latency; 379 unsigned int cfq_target_latency; 380 381 /* 382 * Fallback dummy cfqq for extreme OOM conditions 383 */ 384 struct cfq_queue oom_cfqq; 385 386 unsigned long last_delayed_sync; 387}; 388 389static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 390 391static struct cfq_rb_root *st_for(struct cfq_group *cfqg, 392 enum wl_class_t class, 393 enum wl_type_t type) 394{ 395 if (!cfqg) 396 return NULL; 397 398 if (class == IDLE_WORKLOAD) 399 return &cfqg->service_tree_idle; 400 401 return &cfqg->service_trees[class][type]; 402} 403 404enum cfqq_state_flags { 405 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 406 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 407 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 408 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 409 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 410 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 411 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 412 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 413 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 414 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 415 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 416 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 417 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 418}; 419 420#define CFQ_CFQQ_FNS(name) \ 421static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 422{ \ 423 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 424} \ 425static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 426{ \ 427 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 428} \ 429static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 430{ \ 431 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 432} 433 434CFQ_CFQQ_FNS(on_rr); 435CFQ_CFQQ_FNS(wait_request); 436CFQ_CFQQ_FNS(must_dispatch); 437CFQ_CFQQ_FNS(must_alloc_slice); 438CFQ_CFQQ_FNS(fifo_expire); 439CFQ_CFQQ_FNS(idle_window); 440CFQ_CFQQ_FNS(prio_changed); 441CFQ_CFQQ_FNS(slice_new); 442CFQ_CFQQ_FNS(sync); 443CFQ_CFQQ_FNS(coop); 444CFQ_CFQQ_FNS(split_coop); 445CFQ_CFQQ_FNS(deep); 446CFQ_CFQQ_FNS(wait_busy); 447#undef CFQ_CFQQ_FNS 448 449static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd) 450{ 451 return pd ? container_of(pd, struct cfq_group, pd) : NULL; 452} 453 454static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg) 455{ 456 return pd_to_blkg(&cfqg->pd); 457} 458 459#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP) 460 461/* cfqg stats flags */ 462enum cfqg_stats_flags { 463 CFQG_stats_waiting = 0, 464 CFQG_stats_idling, 465 CFQG_stats_empty, 466}; 467 468#define CFQG_FLAG_FNS(name) \ 469static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \ 470{ \ 471 stats->flags |= (1 << CFQG_stats_##name); \ 472} \ 473static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \ 474{ \ 475 stats->flags &= ~(1 << CFQG_stats_##name); \ 476} \ 477static inline int cfqg_stats_##name(struct cfqg_stats *stats) \ 478{ \ 479 return (stats->flags & (1 << CFQG_stats_##name)) != 0; \ 480} \ 481 482CFQG_FLAG_FNS(waiting) 483CFQG_FLAG_FNS(idling) 484CFQG_FLAG_FNS(empty) 485#undef CFQG_FLAG_FNS 486 487/* This should be called with the queue_lock held. */ 488static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats) 489{ 490 unsigned long long now; 491 492 if (!cfqg_stats_waiting(stats)) 493 return; 494 495 now = sched_clock(); 496 if (time_after64(now, stats->start_group_wait_time)) 497 blkg_stat_add(&stats->group_wait_time, 498 now - stats->start_group_wait_time); 499 cfqg_stats_clear_waiting(stats); 500} 501 502/* This should be called with the queue_lock held. */ 503static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, 504 struct cfq_group *curr_cfqg) 505{ 506 struct cfqg_stats *stats = &cfqg->stats; 507 508 if (cfqg_stats_waiting(stats)) 509 return; 510 if (cfqg == curr_cfqg) 511 return; 512 stats->start_group_wait_time = sched_clock(); 513 cfqg_stats_mark_waiting(stats); 514} 515 516/* This should be called with the queue_lock held. */ 517static void cfqg_stats_end_empty_time(struct cfqg_stats *stats) 518{ 519 unsigned long long now; 520 521 if (!cfqg_stats_empty(stats)) 522 return; 523 524 now = sched_clock(); 525 if (time_after64(now, stats->start_empty_time)) 526 blkg_stat_add(&stats->empty_time, 527 now - stats->start_empty_time); 528 cfqg_stats_clear_empty(stats); 529} 530 531static void cfqg_stats_update_dequeue(struct cfq_group *cfqg) 532{ 533 blkg_stat_add(&cfqg->stats.dequeue, 1); 534} 535 536static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) 537{ 538 struct cfqg_stats *stats = &cfqg->stats; 539 540 if (blkg_rwstat_sum(&stats->queued)) 541 return; 542 543 /* 544 * group is already marked empty. This can happen if cfqq got new 545 * request in parent group and moved to this group while being added 546 * to service tree. Just ignore the event and move on. 547 */ 548 if (cfqg_stats_empty(stats)) 549 return; 550 551 stats->start_empty_time = sched_clock(); 552 cfqg_stats_mark_empty(stats); 553} 554 555static void cfqg_stats_update_idle_time(struct cfq_group *cfqg) 556{ 557 struct cfqg_stats *stats = &cfqg->stats; 558 559 if (cfqg_stats_idling(stats)) { 560 unsigned long long now = sched_clock(); 561 562 if (time_after64(now, stats->start_idle_time)) 563 blkg_stat_add(&stats->idle_time, 564 now - stats->start_idle_time); 565 cfqg_stats_clear_idling(stats); 566 } 567} 568 569static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) 570{ 571 struct cfqg_stats *stats = &cfqg->stats; 572 573 BUG_ON(cfqg_stats_idling(stats)); 574 575 stats->start_idle_time = sched_clock(); 576 cfqg_stats_mark_idling(stats); 577} 578 579static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) 580{ 581 struct cfqg_stats *stats = &cfqg->stats; 582 583 blkg_stat_add(&stats->avg_queue_size_sum, 584 blkg_rwstat_sum(&stats->queued)); 585 blkg_stat_add(&stats->avg_queue_size_samples, 1); 586 cfqg_stats_update_group_wait_time(stats); 587} 588 589#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 590 591static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { } 592static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { } 593static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { } 594static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { } 595static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { } 596static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { } 597static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { } 598 599#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ 600 601#ifdef CONFIG_CFQ_GROUP_IOSCHED 602 603static struct blkcg_policy blkcg_policy_cfq; 604 605static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg) 606{ 607 return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq)); 608} 609 610/* 611 * Determine the parent cfqg for weight calculation. Currently, cfqg 612 * scheduling is flat and the root is the parent of everyone else. 613 */ 614static inline struct cfq_group *cfqg_flat_parent(struct cfq_group *cfqg) 615{ 616 struct blkcg_gq *blkg = cfqg_to_blkg(cfqg); 617 struct cfq_group *root; 618 619 while (blkg->parent) 620 blkg = blkg->parent; 621 root = blkg_to_cfqg(blkg); 622 623 return root != cfqg ? root : NULL; 624} 625 626static inline void cfqg_get(struct cfq_group *cfqg) 627{ 628 return blkg_get(cfqg_to_blkg(cfqg)); 629} 630 631static inline void cfqg_put(struct cfq_group *cfqg) 632{ 633 return blkg_put(cfqg_to_blkg(cfqg)); 634} 635 636#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \ 637 char __pbuf[128]; \ 638 \ 639 blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \ 640 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \ 641 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 642 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\ 643 __pbuf, ##args); \ 644} while (0) 645 646#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \ 647 char __pbuf[128]; \ 648 \ 649 blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \ 650 blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \ 651} while (0) 652 653static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 654 struct cfq_group *curr_cfqg, int rw) 655{ 656 blkg_rwstat_add(&cfqg->stats.queued, rw, 1); 657 cfqg_stats_end_empty_time(&cfqg->stats); 658 cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg); 659} 660 661static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 662 unsigned long time, unsigned long unaccounted_time) 663{ 664 blkg_stat_add(&cfqg->stats.time, time); 665#ifdef CONFIG_DEBUG_BLK_CGROUP 666 blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time); 667#endif 668} 669 670static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) 671{ 672 blkg_rwstat_add(&cfqg->stats.queued, rw, -1); 673} 674 675static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) 676{ 677 blkg_rwstat_add(&cfqg->stats.merged, rw, 1); 678} 679 680static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 681 uint64_t bytes, int rw) 682{ 683 blkg_stat_add(&cfqg->stats.sectors, bytes >> 9); 684 blkg_rwstat_add(&cfqg->stats.serviced, rw, 1); 685 blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes); 686} 687 688static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 689 uint64_t start_time, uint64_t io_start_time, int rw) 690{ 691 struct cfqg_stats *stats = &cfqg->stats; 692 unsigned long long now = sched_clock(); 693 694 if (time_after64(now, io_start_time)) 695 blkg_rwstat_add(&stats->service_time, rw, now - io_start_time); 696 if (time_after64(io_start_time, start_time)) 697 blkg_rwstat_add(&stats->wait_time, rw, 698 io_start_time - start_time); 699} 700 701static void cfq_pd_reset_stats(struct blkcg_gq *blkg) 702{ 703 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 704 struct cfqg_stats *stats = &cfqg->stats; 705 706 /* queued stats shouldn't be cleared */ 707 blkg_rwstat_reset(&stats->service_bytes); 708 blkg_rwstat_reset(&stats->serviced); 709 blkg_rwstat_reset(&stats->merged); 710 blkg_rwstat_reset(&stats->service_time); 711 blkg_rwstat_reset(&stats->wait_time); 712 blkg_stat_reset(&stats->time); 713#ifdef CONFIG_DEBUG_BLK_CGROUP 714 blkg_stat_reset(&stats->unaccounted_time); 715 blkg_stat_reset(&stats->avg_queue_size_sum); 716 blkg_stat_reset(&stats->avg_queue_size_samples); 717 blkg_stat_reset(&stats->dequeue); 718 blkg_stat_reset(&stats->group_wait_time); 719 blkg_stat_reset(&stats->idle_time); 720 blkg_stat_reset(&stats->empty_time); 721#endif 722} 723 724#else /* CONFIG_CFQ_GROUP_IOSCHED */ 725 726static inline struct cfq_group *cfqg_flat_parent(struct cfq_group *cfqg) { return NULL; } 727static inline void cfqg_get(struct cfq_group *cfqg) { } 728static inline void cfqg_put(struct cfq_group *cfqg) { } 729 730#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 731 blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \ 732 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 733 cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\ 734 ##args) 735#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) 736 737static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg, 738 struct cfq_group *curr_cfqg, int rw) { } 739static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg, 740 unsigned long time, unsigned long unaccounted_time) { } 741static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { } 742static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { } 743static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg, 744 uint64_t bytes, int rw) { } 745static inline void cfqg_stats_update_completion(struct cfq_group *cfqg, 746 uint64_t start_time, uint64_t io_start_time, int rw) { } 747 748#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 749 750#define cfq_log(cfqd, fmt, args...) \ 751 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 752 753/* Traverses through cfq group service trees */ 754#define for_each_cfqg_st(cfqg, i, j, st) \ 755 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 756 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 757 : &cfqg->service_tree_idle; \ 758 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 759 (i == IDLE_WORKLOAD && j == 0); \ 760 j++, st = i < IDLE_WORKLOAD ? \ 761 &cfqg->service_trees[i][j]: NULL) \ 762 763static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, 764 struct cfq_ttime *ttime, bool group_idle) 765{ 766 unsigned long slice; 767 if (!sample_valid(ttime->ttime_samples)) 768 return false; 769 if (group_idle) 770 slice = cfqd->cfq_group_idle; 771 else 772 slice = cfqd->cfq_slice_idle; 773 return ttime->ttime_mean > slice; 774} 775 776static inline bool iops_mode(struct cfq_data *cfqd) 777{ 778 /* 779 * If we are not idling on queues and it is a NCQ drive, parallel 780 * execution of requests is on and measuring time is not possible 781 * in most of the cases until and unless we drive shallower queue 782 * depths and that becomes a performance bottleneck. In such cases 783 * switch to start providing fairness in terms of number of IOs. 784 */ 785 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 786 return true; 787 else 788 return false; 789} 790 791static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq) 792{ 793 if (cfq_class_idle(cfqq)) 794 return IDLE_WORKLOAD; 795 if (cfq_class_rt(cfqq)) 796 return RT_WORKLOAD; 797 return BE_WORKLOAD; 798} 799 800 801static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 802{ 803 if (!cfq_cfqq_sync(cfqq)) 804 return ASYNC_WORKLOAD; 805 if (!cfq_cfqq_idle_window(cfqq)) 806 return SYNC_NOIDLE_WORKLOAD; 807 return SYNC_WORKLOAD; 808} 809 810static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class, 811 struct cfq_data *cfqd, 812 struct cfq_group *cfqg) 813{ 814 if (wl_class == IDLE_WORKLOAD) 815 return cfqg->service_tree_idle.count; 816 817 return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count + 818 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count + 819 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count; 820} 821 822static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 823 struct cfq_group *cfqg) 824{ 825 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count + 826 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 827} 828 829static void cfq_dispatch_insert(struct request_queue *, struct request *); 830static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync, 831 struct cfq_io_cq *cic, struct bio *bio, 832 gfp_t gfp_mask); 833 834static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq) 835{ 836 /* cic->icq is the first member, %NULL will convert to %NULL */ 837 return container_of(icq, struct cfq_io_cq, icq); 838} 839 840static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd, 841 struct io_context *ioc) 842{ 843 if (ioc) 844 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue)); 845 return NULL; 846} 847 848static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync) 849{ 850 return cic->cfqq[is_sync]; 851} 852 853static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq, 854 bool is_sync) 855{ 856 cic->cfqq[is_sync] = cfqq; 857} 858 859static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic) 860{ 861 return cic->icq.q->elevator->elevator_data; 862} 863 864/* 865 * We regard a request as SYNC, if it's either a read or has the SYNC bit 866 * set (in which case it could also be direct WRITE). 867 */ 868static inline bool cfq_bio_sync(struct bio *bio) 869{ 870 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 871} 872 873/* 874 * scheduler run of queue, if there are requests pending and no one in the 875 * driver that will restart queueing 876 */ 877static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 878{ 879 if (cfqd->busy_queues) { 880 cfq_log(cfqd, "schedule dispatch"); 881 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 882 } 883} 884 885/* 886 * Scale schedule slice based on io priority. Use the sync time slice only 887 * if a queue is marked sync and has sync io queued. A sync queue with async 888 * io only, should not get full sync slice length. 889 */ 890static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 891 unsigned short prio) 892{ 893 const int base_slice = cfqd->cfq_slice[sync]; 894 895 WARN_ON(prio >= IOPRIO_BE_NR); 896 897 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 898} 899 900static inline int 901cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 902{ 903 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 904} 905 906/** 907 * cfqg_scale_charge - scale disk time charge according to cfqg weight 908 * @charge: disk time being charged 909 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT 910 * 911 * Scale @charge according to @vfraction, which is in range (0, 1]. The 912 * scaling is inversely proportional. 913 * 914 * scaled = charge / vfraction 915 * 916 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT. 917 */ 918static inline u64 cfqg_scale_charge(unsigned long charge, 919 unsigned int vfraction) 920{ 921 u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */ 922 923 /* charge / vfraction */ 924 c <<= CFQ_SERVICE_SHIFT; 925 do_div(c, vfraction); 926 return c; 927} 928 929static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 930{ 931 s64 delta = (s64)(vdisktime - min_vdisktime); 932 if (delta > 0) 933 min_vdisktime = vdisktime; 934 935 return min_vdisktime; 936} 937 938static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 939{ 940 s64 delta = (s64)(vdisktime - min_vdisktime); 941 if (delta < 0) 942 min_vdisktime = vdisktime; 943 944 return min_vdisktime; 945} 946 947static void update_min_vdisktime(struct cfq_rb_root *st) 948{ 949 struct cfq_group *cfqg; 950 951 if (st->left) { 952 cfqg = rb_entry_cfqg(st->left); 953 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 954 cfqg->vdisktime); 955 } 956} 957 958/* 959 * get averaged number of queues of RT/BE priority. 960 * average is updated, with a formula that gives more weight to higher numbers, 961 * to quickly follows sudden increases and decrease slowly 962 */ 963 964static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 965 struct cfq_group *cfqg, bool rt) 966{ 967 unsigned min_q, max_q; 968 unsigned mult = cfq_hist_divisor - 1; 969 unsigned round = cfq_hist_divisor / 2; 970 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 971 972 min_q = min(cfqg->busy_queues_avg[rt], busy); 973 max_q = max(cfqg->busy_queues_avg[rt], busy); 974 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 975 cfq_hist_divisor; 976 return cfqg->busy_queues_avg[rt]; 977} 978 979static inline unsigned 980cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 981{ 982 struct cfq_rb_root *st = &cfqd->grp_service_tree; 983 984 return cfqd->cfq_target_latency * cfqg->weight / st->total_weight; 985} 986 987static inline unsigned 988cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 989{ 990 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 991 if (cfqd->cfq_latency) { 992 /* 993 * interested queues (we consider only the ones with the same 994 * priority class in the cfq group) 995 */ 996 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 997 cfq_class_rt(cfqq)); 998 unsigned sync_slice = cfqd->cfq_slice[1]; 999 unsigned expect_latency = sync_slice * iq; 1000 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 1001 1002 if (expect_latency > group_slice) { 1003 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 1004 /* scale low_slice according to IO priority 1005 * and sync vs async */ 1006 unsigned low_slice = 1007 min(slice, base_low_slice * slice / sync_slice); 1008 /* the adapted slice value is scaled to fit all iqs 1009 * into the target latency */ 1010 slice = max(slice * group_slice / expect_latency, 1011 low_slice); 1012 } 1013 } 1014 return slice; 1015} 1016 1017static inline void 1018cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1019{ 1020 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 1021 1022 cfqq->slice_start = jiffies; 1023 cfqq->slice_end = jiffies + slice; 1024 cfqq->allocated_slice = slice; 1025 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 1026} 1027 1028/* 1029 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 1030 * isn't valid until the first request from the dispatch is activated 1031 * and the slice time set. 1032 */ 1033static inline bool cfq_slice_used(struct cfq_queue *cfqq) 1034{ 1035 if (cfq_cfqq_slice_new(cfqq)) 1036 return false; 1037 if (time_before(jiffies, cfqq->slice_end)) 1038 return false; 1039 1040 return true; 1041} 1042 1043/* 1044 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 1045 * We choose the request that is closest to the head right now. Distance 1046 * behind the head is penalized and only allowed to a certain extent. 1047 */ 1048static struct request * 1049cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 1050{ 1051 sector_t s1, s2, d1 = 0, d2 = 0; 1052 unsigned long back_max; 1053#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 1054#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 1055 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 1056 1057 if (rq1 == NULL || rq1 == rq2) 1058 return rq2; 1059 if (rq2 == NULL) 1060 return rq1; 1061 1062 if (rq_is_sync(rq1) != rq_is_sync(rq2)) 1063 return rq_is_sync(rq1) ? rq1 : rq2; 1064 1065 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) 1066 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; 1067 1068 s1 = blk_rq_pos(rq1); 1069 s2 = blk_rq_pos(rq2); 1070 1071 /* 1072 * by definition, 1KiB is 2 sectors 1073 */ 1074 back_max = cfqd->cfq_back_max * 2; 1075 1076 /* 1077 * Strict one way elevator _except_ in the case where we allow 1078 * short backward seeks which are biased as twice the cost of a 1079 * similar forward seek. 1080 */ 1081 if (s1 >= last) 1082 d1 = s1 - last; 1083 else if (s1 + back_max >= last) 1084 d1 = (last - s1) * cfqd->cfq_back_penalty; 1085 else 1086 wrap |= CFQ_RQ1_WRAP; 1087 1088 if (s2 >= last) 1089 d2 = s2 - last; 1090 else if (s2 + back_max >= last) 1091 d2 = (last - s2) * cfqd->cfq_back_penalty; 1092 else 1093 wrap |= CFQ_RQ2_WRAP; 1094 1095 /* Found required data */ 1096 1097 /* 1098 * By doing switch() on the bit mask "wrap" we avoid having to 1099 * check two variables for all permutations: --> faster! 1100 */ 1101 switch (wrap) { 1102 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 1103 if (d1 < d2) 1104 return rq1; 1105 else if (d2 < d1) 1106 return rq2; 1107 else { 1108 if (s1 >= s2) 1109 return rq1; 1110 else 1111 return rq2; 1112 } 1113 1114 case CFQ_RQ2_WRAP: 1115 return rq1; 1116 case CFQ_RQ1_WRAP: 1117 return rq2; 1118 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 1119 default: 1120 /* 1121 * Since both rqs are wrapped, 1122 * start with the one that's further behind head 1123 * (--> only *one* back seek required), 1124 * since back seek takes more time than forward. 1125 */ 1126 if (s1 <= s2) 1127 return rq1; 1128 else 1129 return rq2; 1130 } 1131} 1132 1133/* 1134 * The below is leftmost cache rbtree addon 1135 */ 1136static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 1137{ 1138 /* Service tree is empty */ 1139 if (!root->count) 1140 return NULL; 1141 1142 if (!root->left) 1143 root->left = rb_first(&root->rb); 1144 1145 if (root->left) 1146 return rb_entry(root->left, struct cfq_queue, rb_node); 1147 1148 return NULL; 1149} 1150 1151static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 1152{ 1153 if (!root->left) 1154 root->left = rb_first(&root->rb); 1155 1156 if (root->left) 1157 return rb_entry_cfqg(root->left); 1158 1159 return NULL; 1160} 1161 1162static void rb_erase_init(struct rb_node *n, struct rb_root *root) 1163{ 1164 rb_erase(n, root); 1165 RB_CLEAR_NODE(n); 1166} 1167 1168static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 1169{ 1170 if (root->left == n) 1171 root->left = NULL; 1172 rb_erase_init(n, &root->rb); 1173 --root->count; 1174} 1175 1176/* 1177 * would be nice to take fifo expire time into account as well 1178 */ 1179static struct request * 1180cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1181 struct request *last) 1182{ 1183 struct rb_node *rbnext = rb_next(&last->rb_node); 1184 struct rb_node *rbprev = rb_prev(&last->rb_node); 1185 struct request *next = NULL, *prev = NULL; 1186 1187 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 1188 1189 if (rbprev) 1190 prev = rb_entry_rq(rbprev); 1191 1192 if (rbnext) 1193 next = rb_entry_rq(rbnext); 1194 else { 1195 rbnext = rb_first(&cfqq->sort_list); 1196 if (rbnext && rbnext != &last->rb_node) 1197 next = rb_entry_rq(rbnext); 1198 } 1199 1200 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 1201} 1202 1203static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 1204 struct cfq_queue *cfqq) 1205{ 1206 /* 1207 * just an approximation, should be ok. 1208 */ 1209 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 1210 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 1211} 1212 1213static inline s64 1214cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 1215{ 1216 return cfqg->vdisktime - st->min_vdisktime; 1217} 1218 1219static void 1220__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1221{ 1222 struct rb_node **node = &st->rb.rb_node; 1223 struct rb_node *parent = NULL; 1224 struct cfq_group *__cfqg; 1225 s64 key = cfqg_key(st, cfqg); 1226 int left = 1; 1227 1228 while (*node != NULL) { 1229 parent = *node; 1230 __cfqg = rb_entry_cfqg(parent); 1231 1232 if (key < cfqg_key(st, __cfqg)) 1233 node = &parent->rb_left; 1234 else { 1235 node = &parent->rb_right; 1236 left = 0; 1237 } 1238 } 1239 1240 if (left) 1241 st->left = &cfqg->rb_node; 1242 1243 rb_link_node(&cfqg->rb_node, parent, node); 1244 rb_insert_color(&cfqg->rb_node, &st->rb); 1245} 1246 1247static void 1248cfq_update_group_weight(struct cfq_group *cfqg) 1249{ 1250 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1251 1252 if (cfqg->new_weight) { 1253 cfqg->weight = cfqg->new_weight; 1254 cfqg->new_weight = 0; 1255 } 1256 1257 if (cfqg->new_leaf_weight) { 1258 cfqg->leaf_weight = cfqg->new_leaf_weight; 1259 cfqg->new_leaf_weight = 0; 1260 } 1261} 1262 1263static void 1264cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 1265{ 1266 unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */ 1267 struct cfq_group *pos = cfqg; 1268 struct cfq_group *parent; 1269 bool propagate; 1270 1271 /* add to the service tree */ 1272 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 1273 1274 cfq_update_group_weight(cfqg); 1275 __cfq_group_service_tree_add(st, cfqg); 1276 st->total_weight += cfqg->weight; 1277 1278 /* 1279 * Activate @cfqg and calculate the portion of vfraction @cfqg is 1280 * entitled to. vfraction is calculated by walking the tree 1281 * towards the root calculating the fraction it has at each level. 1282 * The compounded ratio is how much vfraction @cfqg owns. 1283 * 1284 * Start with the proportion tasks in this cfqg has against active 1285 * children cfqgs - its leaf_weight against children_weight. 1286 */ 1287 propagate = !pos->nr_active++; 1288 pos->children_weight += pos->leaf_weight; 1289 vfr = vfr * pos->leaf_weight / pos->children_weight; 1290 1291 /* 1292 * Compound ->weight walking up the tree. Both activation and 1293 * vfraction calculation are done in the same loop. Propagation 1294 * stops once an already activated node is met. vfraction 1295 * calculation should always continue to the root. 1296 */ 1297 while ((parent = cfqg_flat_parent(pos))) { 1298 if (propagate) { 1299 propagate = !parent->nr_active++; 1300 parent->children_weight += pos->weight; 1301 } 1302 vfr = vfr * pos->weight / parent->children_weight; 1303 pos = parent; 1304 } 1305 1306 cfqg->vfraction = max_t(unsigned, vfr, 1); 1307} 1308 1309static void 1310cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 1311{ 1312 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1313 struct cfq_group *__cfqg; 1314 struct rb_node *n; 1315 1316 cfqg->nr_cfqq++; 1317 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1318 return; 1319 1320 /* 1321 * Currently put the group at the end. Later implement something 1322 * so that groups get lesser vtime based on their weights, so that 1323 * if group does not loose all if it was not continuously backlogged. 1324 */ 1325 n = rb_last(&st->rb); 1326 if (n) { 1327 __cfqg = rb_entry_cfqg(n); 1328 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 1329 } else 1330 cfqg->vdisktime = st->min_vdisktime; 1331 cfq_group_service_tree_add(st, cfqg); 1332} 1333 1334static void 1335cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 1336{ 1337 struct cfq_group *pos = cfqg; 1338 bool propagate; 1339 1340 /* 1341 * Undo activation from cfq_group_service_tree_add(). Deactivate 1342 * @cfqg and propagate deactivation upwards. 1343 */ 1344 propagate = !--pos->nr_active; 1345 pos->children_weight -= pos->leaf_weight; 1346 1347 while (propagate) { 1348 struct cfq_group *parent = cfqg_flat_parent(pos); 1349 1350 /* @pos has 0 nr_active at this point */ 1351 WARN_ON_ONCE(pos->children_weight); 1352 pos->vfraction = 0; 1353 1354 if (!parent) 1355 break; 1356 1357 propagate = !--parent->nr_active; 1358 parent->children_weight -= pos->weight; 1359 pos = parent; 1360 } 1361 1362 /* remove from the service tree */ 1363 st->total_weight -= cfqg->weight; 1364 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 1365 cfq_rb_erase(&cfqg->rb_node, st); 1366} 1367 1368static void 1369cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 1370{ 1371 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1372 1373 BUG_ON(cfqg->nr_cfqq < 1); 1374 cfqg->nr_cfqq--; 1375 1376 /* If there are other cfq queues under this group, don't delete it */ 1377 if (cfqg->nr_cfqq) 1378 return; 1379 1380 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 1381 cfq_group_service_tree_del(st, cfqg); 1382 cfqg->saved_wl_slice = 0; 1383 cfqg_stats_update_dequeue(cfqg); 1384} 1385 1386static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 1387 unsigned int *unaccounted_time) 1388{ 1389 unsigned int slice_used; 1390 1391 /* 1392 * Queue got expired before even a single request completed or 1393 * got expired immediately after first request completion. 1394 */ 1395 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 1396 /* 1397 * Also charge the seek time incurred to the group, otherwise 1398 * if there are mutiple queues in the group, each can dispatch 1399 * a single request on seeky media and cause lots of seek time 1400 * and group will never know it. 1401 */ 1402 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 1403 1); 1404 } else { 1405 slice_used = jiffies - cfqq->slice_start; 1406 if (slice_used > cfqq->allocated_slice) { 1407 *unaccounted_time = slice_used - cfqq->allocated_slice; 1408 slice_used = cfqq->allocated_slice; 1409 } 1410 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 1411 *unaccounted_time += cfqq->slice_start - 1412 cfqq->dispatch_start; 1413 } 1414 1415 return slice_used; 1416} 1417 1418static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 1419 struct cfq_queue *cfqq) 1420{ 1421 struct cfq_rb_root *st = &cfqd->grp_service_tree; 1422 unsigned int used_sl, charge, unaccounted_sl = 0; 1423 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 1424 - cfqg->service_tree_idle.count; 1425 unsigned int vfr; 1426 1427 BUG_ON(nr_sync < 0); 1428 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 1429 1430 if (iops_mode(cfqd)) 1431 charge = cfqq->slice_dispatch; 1432 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 1433 charge = cfqq->allocated_slice; 1434 1435 /* 1436 * Can't update vdisktime while on service tree and cfqg->vfraction 1437 * is valid only while on it. Cache vfr, leave the service tree, 1438 * update vdisktime and go back on. The re-addition to the tree 1439 * will also update the weights as necessary. 1440 */ 1441 vfr = cfqg->vfraction; 1442 cfq_group_service_tree_del(st, cfqg); 1443 cfqg->vdisktime += cfqg_scale_charge(charge, vfr); 1444 cfq_group_service_tree_add(st, cfqg); 1445 1446 /* This group is being expired. Save the context */ 1447 if (time_after(cfqd->workload_expires, jiffies)) { 1448 cfqg->saved_wl_slice = cfqd->workload_expires 1449 - jiffies; 1450 cfqg->saved_wl_type = cfqd->serving_wl_type; 1451 cfqg->saved_wl_class = cfqd->serving_wl_class; 1452 } else 1453 cfqg->saved_wl_slice = 0; 1454 1455 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 1456 st->min_vdisktime); 1457 cfq_log_cfqq(cfqq->cfqd, cfqq, 1458 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", 1459 used_sl, cfqq->slice_dispatch, charge, 1460 iops_mode(cfqd), cfqq->nr_sectors); 1461 cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl); 1462 cfqg_stats_set_start_empty_time(cfqg); 1463} 1464 1465/** 1466 * cfq_init_cfqg_base - initialize base part of a cfq_group 1467 * @cfqg: cfq_group to initialize 1468 * 1469 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED 1470 * is enabled or not. 1471 */ 1472static void cfq_init_cfqg_base(struct cfq_group *cfqg) 1473{ 1474 struct cfq_rb_root *st; 1475 int i, j; 1476 1477 for_each_cfqg_st(cfqg, i, j, st) 1478 *st = CFQ_RB_ROOT; 1479 RB_CLEAR_NODE(&cfqg->rb_node); 1480 1481 cfqg->ttime.last_end_request = jiffies; 1482} 1483 1484#ifdef CONFIG_CFQ_GROUP_IOSCHED 1485static void cfq_pd_init(struct blkcg_gq *blkg) 1486{ 1487 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1488 1489 cfq_init_cfqg_base(cfqg); 1490 cfqg->weight = blkg->blkcg->cfq_weight; 1491 cfqg->leaf_weight = blkg->blkcg->cfq_leaf_weight; 1492} 1493 1494/* 1495 * Search for the cfq group current task belongs to. request_queue lock must 1496 * be held. 1497 */ 1498static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1499 struct blkcg *blkcg) 1500{ 1501 struct request_queue *q = cfqd->queue; 1502 struct cfq_group *cfqg = NULL; 1503 1504 /* avoid lookup for the common case where there's no blkcg */ 1505 if (blkcg == &blkcg_root) { 1506 cfqg = cfqd->root_group; 1507 } else { 1508 struct blkcg_gq *blkg; 1509 1510 blkg = blkg_lookup_create(blkcg, q); 1511 if (!IS_ERR(blkg)) 1512 cfqg = blkg_to_cfqg(blkg); 1513 } 1514 1515 return cfqg; 1516} 1517 1518static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1519{ 1520 /* Currently, all async queues are mapped to root group */ 1521 if (!cfq_cfqq_sync(cfqq)) 1522 cfqg = cfqq->cfqd->root_group; 1523 1524 cfqq->cfqg = cfqg; 1525 /* cfqq reference on cfqg */ 1526 cfqg_get(cfqg); 1527} 1528 1529static u64 cfqg_prfill_weight_device(struct seq_file *sf, 1530 struct blkg_policy_data *pd, int off) 1531{ 1532 struct cfq_group *cfqg = pd_to_cfqg(pd); 1533 1534 if (!cfqg->dev_weight) 1535 return 0; 1536 return __blkg_prfill_u64(sf, pd, cfqg->dev_weight); 1537} 1538 1539static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft, 1540 struct seq_file *sf) 1541{ 1542 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), 1543 cfqg_prfill_weight_device, &blkcg_policy_cfq, 0, 1544 false); 1545 return 0; 1546} 1547 1548static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf, 1549 struct blkg_policy_data *pd, int off) 1550{ 1551 struct cfq_group *cfqg = pd_to_cfqg(pd); 1552 1553 if (!cfqg->dev_leaf_weight) 1554 return 0; 1555 return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight); 1556} 1557 1558static int cfqg_print_leaf_weight_device(struct cgroup *cgrp, 1559 struct cftype *cft, 1560 struct seq_file *sf) 1561{ 1562 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), 1563 cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq, 0, 1564 false); 1565 return 0; 1566} 1567 1568static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft, 1569 struct seq_file *sf) 1570{ 1571 seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight); 1572 return 0; 1573} 1574 1575static int cfq_print_leaf_weight(struct cgroup *cgrp, struct cftype *cft, 1576 struct seq_file *sf) 1577{ 1578 seq_printf(sf, "%u\n", 1579 cgroup_to_blkcg(cgrp)->cfq_leaf_weight); 1580 return 0; 1581} 1582 1583static int __cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft, 1584 const char *buf, bool is_leaf_weight) 1585{ 1586 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1587 struct blkg_conf_ctx ctx; 1588 struct cfq_group *cfqg; 1589 int ret; 1590 1591 ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx); 1592 if (ret) 1593 return ret; 1594 1595 ret = -EINVAL; 1596 cfqg = blkg_to_cfqg(ctx.blkg); 1597 if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) { 1598 if (!is_leaf_weight) { 1599 cfqg->dev_weight = ctx.v; 1600 cfqg->new_weight = ctx.v ?: blkcg->cfq_weight; 1601 } else { 1602 cfqg->dev_leaf_weight = ctx.v; 1603 cfqg->new_leaf_weight = ctx.v ?: blkcg->cfq_leaf_weight; 1604 } 1605 ret = 0; 1606 } 1607 1608 blkg_conf_finish(&ctx); 1609 return ret; 1610} 1611 1612static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft, 1613 const char *buf) 1614{ 1615 return __cfqg_set_weight_device(cgrp, cft, buf, false); 1616} 1617 1618static int cfqg_set_leaf_weight_device(struct cgroup *cgrp, struct cftype *cft, 1619 const char *buf) 1620{ 1621 return __cfqg_set_weight_device(cgrp, cft, buf, true); 1622} 1623 1624static int __cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val, 1625 bool is_leaf_weight) 1626{ 1627 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1628 struct blkcg_gq *blkg; 1629 struct hlist_node *n; 1630 1631 if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX) 1632 return -EINVAL; 1633 1634 spin_lock_irq(&blkcg->lock); 1635 1636 if (!is_leaf_weight) 1637 blkcg->cfq_weight = val; 1638 else 1639 blkcg->cfq_leaf_weight = val; 1640 1641 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { 1642 struct cfq_group *cfqg = blkg_to_cfqg(blkg); 1643 1644 if (!cfqg) 1645 continue; 1646 1647 if (!is_leaf_weight) { 1648 if (!cfqg->dev_weight) 1649 cfqg->new_weight = blkcg->cfq_weight; 1650 } else { 1651 if (!cfqg->dev_leaf_weight) 1652 cfqg->new_leaf_weight = blkcg->cfq_leaf_weight; 1653 } 1654 } 1655 1656 spin_unlock_irq(&blkcg->lock); 1657 return 0; 1658} 1659 1660static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val) 1661{ 1662 return __cfq_set_weight(cgrp, cft, val, false); 1663} 1664 1665static int cfq_set_leaf_weight(struct cgroup *cgrp, struct cftype *cft, u64 val) 1666{ 1667 return __cfq_set_weight(cgrp, cft, val, true); 1668} 1669 1670static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft, 1671 struct seq_file *sf) 1672{ 1673 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1674 1675 blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq, 1676 cft->private, false); 1677 return 0; 1678} 1679 1680static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft, 1681 struct seq_file *sf) 1682{ 1683 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1684 1685 blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq, 1686 cft->private, true); 1687 return 0; 1688} 1689 1690#ifdef CONFIG_DEBUG_BLK_CGROUP 1691static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, 1692 struct blkg_policy_data *pd, int off) 1693{ 1694 struct cfq_group *cfqg = pd_to_cfqg(pd); 1695 u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples); 1696 u64 v = 0; 1697 1698 if (samples) { 1699 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum); 1700 do_div(v, samples); 1701 } 1702 __blkg_prfill_u64(sf, pd, v); 1703 return 0; 1704} 1705 1706/* print avg_queue_size */ 1707static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft, 1708 struct seq_file *sf) 1709{ 1710 struct blkcg *blkcg = cgroup_to_blkcg(cgrp); 1711 1712 blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size, 1713 &blkcg_policy_cfq, 0, false); 1714 return 0; 1715} 1716#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1717 1718static struct cftype cfq_blkcg_files[] = { 1719 /* on root, weight is mapped to leaf_weight */ 1720 { 1721 .name = "weight_device", 1722 .flags = CFTYPE_ONLY_ON_ROOT, 1723 .read_seq_string = cfqg_print_leaf_weight_device, 1724 .write_string = cfqg_set_leaf_weight_device, 1725 .max_write_len = 256, 1726 }, 1727 { 1728 .name = "weight", 1729 .flags = CFTYPE_ONLY_ON_ROOT, 1730 .read_seq_string = cfq_print_leaf_weight, 1731 .write_u64 = cfq_set_leaf_weight, 1732 }, 1733 1734 /* no such mapping necessary for !roots */ 1735 { 1736 .name = "weight_device", 1737 .flags = CFTYPE_NOT_ON_ROOT, 1738 .read_seq_string = cfqg_print_weight_device, 1739 .write_string = cfqg_set_weight_device, 1740 .max_write_len = 256, 1741 }, 1742 { 1743 .name = "weight", 1744 .flags = CFTYPE_NOT_ON_ROOT, 1745 .read_seq_string = cfq_print_weight, 1746 .write_u64 = cfq_set_weight, 1747 }, 1748 1749 { 1750 .name = "leaf_weight_device", 1751 .read_seq_string = cfqg_print_leaf_weight_device, 1752 .write_string = cfqg_set_leaf_weight_device, 1753 .max_write_len = 256, 1754 }, 1755 { 1756 .name = "leaf_weight", 1757 .read_seq_string = cfq_print_leaf_weight, 1758 .write_u64 = cfq_set_leaf_weight, 1759 }, 1760 1761 { 1762 .name = "time", 1763 .private = offsetof(struct cfq_group, stats.time), 1764 .read_seq_string = cfqg_print_stat, 1765 }, 1766 { 1767 .name = "sectors", 1768 .private = offsetof(struct cfq_group, stats.sectors), 1769 .read_seq_string = cfqg_print_stat, 1770 }, 1771 { 1772 .name = "io_service_bytes", 1773 .private = offsetof(struct cfq_group, stats.service_bytes), 1774 .read_seq_string = cfqg_print_rwstat, 1775 }, 1776 { 1777 .name = "io_serviced", 1778 .private = offsetof(struct cfq_group, stats.serviced), 1779 .read_seq_string = cfqg_print_rwstat, 1780 }, 1781 { 1782 .name = "io_service_time", 1783 .private = offsetof(struct cfq_group, stats.service_time), 1784 .read_seq_string = cfqg_print_rwstat, 1785 }, 1786 { 1787 .name = "io_wait_time", 1788 .private = offsetof(struct cfq_group, stats.wait_time), 1789 .read_seq_string = cfqg_print_rwstat, 1790 }, 1791 { 1792 .name = "io_merged", 1793 .private = offsetof(struct cfq_group, stats.merged), 1794 .read_seq_string = cfqg_print_rwstat, 1795 }, 1796 { 1797 .name = "io_queued", 1798 .private = offsetof(struct cfq_group, stats.queued), 1799 .read_seq_string = cfqg_print_rwstat, 1800 }, 1801#ifdef CONFIG_DEBUG_BLK_CGROUP 1802 { 1803 .name = "avg_queue_size", 1804 .read_seq_string = cfqg_print_avg_queue_size, 1805 }, 1806 { 1807 .name = "group_wait_time", 1808 .private = offsetof(struct cfq_group, stats.group_wait_time), 1809 .read_seq_string = cfqg_print_stat, 1810 }, 1811 { 1812 .name = "idle_time", 1813 .private = offsetof(struct cfq_group, stats.idle_time), 1814 .read_seq_string = cfqg_print_stat, 1815 }, 1816 { 1817 .name = "empty_time", 1818 .private = offsetof(struct cfq_group, stats.empty_time), 1819 .read_seq_string = cfqg_print_stat, 1820 }, 1821 { 1822 .name = "dequeue", 1823 .private = offsetof(struct cfq_group, stats.dequeue), 1824 .read_seq_string = cfqg_print_stat, 1825 }, 1826 { 1827 .name = "unaccounted_time", 1828 .private = offsetof(struct cfq_group, stats.unaccounted_time), 1829 .read_seq_string = cfqg_print_stat, 1830 }, 1831#endif /* CONFIG_DEBUG_BLK_CGROUP */ 1832 { } /* terminate */ 1833}; 1834#else /* GROUP_IOSCHED */ 1835static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd, 1836 struct blkcg *blkcg) 1837{ 1838 return cfqd->root_group; 1839} 1840 1841static inline void 1842cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1843 cfqq->cfqg = cfqg; 1844} 1845 1846#endif /* GROUP_IOSCHED */ 1847 1848/* 1849 * The cfqd->service_trees holds all pending cfq_queue's that have 1850 * requests waiting to be processed. It is sorted in the order that 1851 * we will service the queues. 1852 */ 1853static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1854 bool add_front) 1855{ 1856 struct rb_node **p, *parent; 1857 struct cfq_queue *__cfqq; 1858 unsigned long rb_key; 1859 struct cfq_rb_root *st; 1860 int left; 1861 int new_cfqq = 1; 1862 1863 st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq)); 1864 if (cfq_class_idle(cfqq)) { 1865 rb_key = CFQ_IDLE_DELAY; 1866 parent = rb_last(&st->rb); 1867 if (parent && parent != &cfqq->rb_node) { 1868 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1869 rb_key += __cfqq->rb_key; 1870 } else 1871 rb_key += jiffies; 1872 } else if (!add_front) { 1873 /* 1874 * Get our rb key offset. Subtract any residual slice 1875 * value carried from last service. A negative resid 1876 * count indicates slice overrun, and this should position 1877 * the next service time further away in the tree. 1878 */ 1879 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1880 rb_key -= cfqq->slice_resid; 1881 cfqq->slice_resid = 0; 1882 } else { 1883 rb_key = -HZ; 1884 __cfqq = cfq_rb_first(st); 1885 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1886 } 1887 1888 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1889 new_cfqq = 0; 1890 /* 1891 * same position, nothing more to do 1892 */ 1893 if (rb_key == cfqq->rb_key && cfqq->service_tree == st) 1894 return; 1895 1896 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1897 cfqq->service_tree = NULL; 1898 } 1899 1900 left = 1; 1901 parent = NULL; 1902 cfqq->service_tree = st; 1903 p = &st->rb.rb_node; 1904 while (*p) { 1905 parent = *p; 1906 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1907 1908 /* 1909 * sort by key, that represents service time. 1910 */ 1911 if (time_before(rb_key, __cfqq->rb_key)) 1912 p = &parent->rb_left; 1913 else { 1914 p = &parent->rb_right; 1915 left = 0; 1916 } 1917 } 1918 1919 if (left) 1920 st->left = &cfqq->rb_node; 1921 1922 cfqq->rb_key = rb_key; 1923 rb_link_node(&cfqq->rb_node, parent, p); 1924 rb_insert_color(&cfqq->rb_node, &st->rb); 1925 st->count++; 1926 if (add_front || !new_cfqq) 1927 return; 1928 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1929} 1930 1931static struct cfq_queue * 1932cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1933 sector_t sector, struct rb_node **ret_parent, 1934 struct rb_node ***rb_link) 1935{ 1936 struct rb_node **p, *parent; 1937 struct cfq_queue *cfqq = NULL; 1938 1939 parent = NULL; 1940 p = &root->rb_node; 1941 while (*p) { 1942 struct rb_node **n; 1943 1944 parent = *p; 1945 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1946 1947 /* 1948 * Sort strictly based on sector. Smallest to the left, 1949 * largest to the right. 1950 */ 1951 if (sector > blk_rq_pos(cfqq->next_rq)) 1952 n = &(*p)->rb_right; 1953 else if (sector < blk_rq_pos(cfqq->next_rq)) 1954 n = &(*p)->rb_left; 1955 else 1956 break; 1957 p = n; 1958 cfqq = NULL; 1959 } 1960 1961 *ret_parent = parent; 1962 if (rb_link) 1963 *rb_link = p; 1964 return cfqq; 1965} 1966 1967static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1968{ 1969 struct rb_node **p, *parent; 1970 struct cfq_queue *__cfqq; 1971 1972 if (cfqq->p_root) { 1973 rb_erase(&cfqq->p_node, cfqq->p_root); 1974 cfqq->p_root = NULL; 1975 } 1976 1977 if (cfq_class_idle(cfqq)) 1978 return; 1979 if (!cfqq->next_rq) 1980 return; 1981 1982 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1983 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1984 blk_rq_pos(cfqq->next_rq), &parent, &p); 1985 if (!__cfqq) { 1986 rb_link_node(&cfqq->p_node, parent, p); 1987 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1988 } else 1989 cfqq->p_root = NULL; 1990} 1991 1992/* 1993 * Update cfqq's position in the service tree. 1994 */ 1995static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1996{ 1997 /* 1998 * Resorting requires the cfqq to be on the RR list already. 1999 */ 2000 if (cfq_cfqq_on_rr(cfqq)) { 2001 cfq_service_tree_add(cfqd, cfqq, 0); 2002 cfq_prio_tree_add(cfqd, cfqq); 2003 } 2004} 2005 2006/* 2007 * add to busy list of queues for service, trying to be fair in ordering 2008 * the pending list according to last request service 2009 */ 2010static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2011{ 2012 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 2013 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2014 cfq_mark_cfqq_on_rr(cfqq); 2015 cfqd->busy_queues++; 2016 if (cfq_cfqq_sync(cfqq)) 2017 cfqd->busy_sync_queues++; 2018 2019 cfq_resort_rr_list(cfqd, cfqq); 2020} 2021 2022/* 2023 * Called when the cfqq no longer has requests pending, remove it from 2024 * the service tree. 2025 */ 2026static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2027{ 2028 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 2029 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 2030 cfq_clear_cfqq_on_rr(cfqq); 2031 2032 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 2033 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 2034 cfqq->service_tree = NULL; 2035 } 2036 if (cfqq->p_root) { 2037 rb_erase(&cfqq->p_node, cfqq->p_root); 2038 cfqq->p_root = NULL; 2039 } 2040 2041 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 2042 BUG_ON(!cfqd->busy_queues); 2043 cfqd->busy_queues--; 2044 if (cfq_cfqq_sync(cfqq)) 2045 cfqd->busy_sync_queues--; 2046} 2047 2048/* 2049 * rb tree support functions 2050 */ 2051static void cfq_del_rq_rb(struct request *rq) 2052{ 2053 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2054 const int sync = rq_is_sync(rq); 2055 2056 BUG_ON(!cfqq->queued[sync]); 2057 cfqq->queued[sync]--; 2058 2059 elv_rb_del(&cfqq->sort_list, rq); 2060 2061 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 2062 /* 2063 * Queue will be deleted from service tree when we actually 2064 * expire it later. Right now just remove it from prio tree 2065 * as it is empty. 2066 */ 2067 if (cfqq->p_root) { 2068 rb_erase(&cfqq->p_node, cfqq->p_root); 2069 cfqq->p_root = NULL; 2070 } 2071 } 2072} 2073 2074static void cfq_add_rq_rb(struct request *rq) 2075{ 2076 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2077 struct cfq_data *cfqd = cfqq->cfqd; 2078 struct request *prev; 2079 2080 cfqq->queued[rq_is_sync(rq)]++; 2081 2082 elv_rb_add(&cfqq->sort_list, rq); 2083 2084 if (!cfq_cfqq_on_rr(cfqq)) 2085 cfq_add_cfqq_rr(cfqd, cfqq); 2086 2087 /* 2088 * check if this request is a better next-serve candidate 2089 */ 2090 prev = cfqq->next_rq; 2091 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 2092 2093 /* 2094 * adjust priority tree position, if ->next_rq changes 2095 */ 2096 if (prev != cfqq->next_rq) 2097 cfq_prio_tree_add(cfqd, cfqq); 2098 2099 BUG_ON(!cfqq->next_rq); 2100} 2101 2102static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 2103{ 2104 elv_rb_del(&cfqq->sort_list, rq); 2105 cfqq->queued[rq_is_sync(rq)]--; 2106 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 2107 cfq_add_rq_rb(rq); 2108 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group, 2109 rq->cmd_flags); 2110} 2111 2112static struct request * 2113cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 2114{ 2115 struct task_struct *tsk = current; 2116 struct cfq_io_cq *cic; 2117 struct cfq_queue *cfqq; 2118 2119 cic = cfq_cic_lookup(cfqd, tsk->io_context); 2120 if (!cic) 2121 return NULL; 2122 2123 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 2124 if (cfqq) { 2125 sector_t sector = bio->bi_sector + bio_sectors(bio); 2126 2127 return elv_rb_find(&cfqq->sort_list, sector); 2128 } 2129 2130 return NULL; 2131} 2132 2133static void cfq_activate_request(struct request_queue *q, struct request *rq) 2134{ 2135 struct cfq_data *cfqd = q->elevator->elevator_data; 2136 2137 cfqd->rq_in_driver++; 2138 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 2139 cfqd->rq_in_driver); 2140 2141 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 2142} 2143 2144static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 2145{ 2146 struct cfq_data *cfqd = q->elevator->elevator_data; 2147 2148 WARN_ON(!cfqd->rq_in_driver); 2149 cfqd->rq_in_driver--; 2150 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 2151 cfqd->rq_in_driver); 2152} 2153 2154static void cfq_remove_request(struct request *rq) 2155{ 2156 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2157 2158 if (cfqq->next_rq == rq) 2159 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 2160 2161 list_del_init(&rq->queuelist); 2162 cfq_del_rq_rb(rq); 2163 2164 cfqq->cfqd->rq_queued--; 2165 cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags); 2166 if (rq->cmd_flags & REQ_PRIO) { 2167 WARN_ON(!cfqq->prio_pending); 2168 cfqq->prio_pending--; 2169 } 2170} 2171 2172static int cfq_merge(struct request_queue *q, struct request **req, 2173 struct bio *bio) 2174{ 2175 struct cfq_data *cfqd = q->elevator->elevator_data; 2176 struct request *__rq; 2177 2178 __rq = cfq_find_rq_fmerge(cfqd, bio); 2179 if (__rq && elv_rq_merge_ok(__rq, bio)) { 2180 *req = __rq; 2181 return ELEVATOR_FRONT_MERGE; 2182 } 2183 2184 return ELEVATOR_NO_MERGE; 2185} 2186 2187static void cfq_merged_request(struct request_queue *q, struct request *req, 2188 int type) 2189{ 2190 if (type == ELEVATOR_FRONT_MERGE) { 2191 struct cfq_queue *cfqq = RQ_CFQQ(req); 2192 2193 cfq_reposition_rq_rb(cfqq, req); 2194 } 2195} 2196 2197static void cfq_bio_merged(struct request_queue *q, struct request *req, 2198 struct bio *bio) 2199{ 2200 cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw); 2201} 2202 2203static void 2204cfq_merged_requests(struct request_queue *q, struct request *rq, 2205 struct request *next) 2206{ 2207 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2208 struct cfq_data *cfqd = q->elevator->elevator_data; 2209 2210 /* 2211 * reposition in fifo if next is older than rq 2212 */ 2213 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 2214 time_before(rq_fifo_time(next), rq_fifo_time(rq)) && 2215 cfqq == RQ_CFQQ(next)) { 2216 list_move(&rq->queuelist, &next->queuelist); 2217 rq_set_fifo_time(rq, rq_fifo_time(next)); 2218 } 2219 2220 if (cfqq->next_rq == next) 2221 cfqq->next_rq = rq; 2222 cfq_remove_request(next); 2223 cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags); 2224 2225 cfqq = RQ_CFQQ(next); 2226 /* 2227 * all requests of this queue are merged to other queues, delete it 2228 * from the service tree. If it's the active_queue, 2229 * cfq_dispatch_requests() will choose to expire it or do idle 2230 */ 2231 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && 2232 cfqq != cfqd->active_queue) 2233 cfq_del_cfqq_rr(cfqd, cfqq); 2234} 2235 2236static int cfq_allow_merge(struct request_queue *q, struct request *rq, 2237 struct bio *bio) 2238{ 2239 struct cfq_data *cfqd = q->elevator->elevator_data; 2240 struct cfq_io_cq *cic; 2241 struct cfq_queue *cfqq; 2242 2243 /* 2244 * Disallow merge of a sync bio into an async request. 2245 */ 2246 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 2247 return false; 2248 2249 /* 2250 * Lookup the cfqq that this bio will be queued with and allow 2251 * merge only if rq is queued there. 2252 */ 2253 cic = cfq_cic_lookup(cfqd, current->io_context); 2254 if (!cic) 2255 return false; 2256 2257 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 2258 return cfqq == RQ_CFQQ(rq); 2259} 2260 2261static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2262{ 2263 del_timer(&cfqd->idle_slice_timer); 2264 cfqg_stats_update_idle_time(cfqq->cfqg); 2265} 2266 2267static void __cfq_set_active_queue(struct cfq_data *cfqd, 2268 struct cfq_queue *cfqq) 2269{ 2270 if (cfqq) { 2271 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d", 2272 cfqd->serving_wl_class, cfqd->serving_wl_type); 2273 cfqg_stats_update_avg_queue_size(cfqq->cfqg); 2274 cfqq->slice_start = 0; 2275 cfqq->dispatch_start = jiffies; 2276 cfqq->allocated_slice = 0; 2277 cfqq->slice_end = 0; 2278 cfqq->slice_dispatch = 0; 2279 cfqq->nr_sectors = 0; 2280 2281 cfq_clear_cfqq_wait_request(cfqq); 2282 cfq_clear_cfqq_must_dispatch(cfqq); 2283 cfq_clear_cfqq_must_alloc_slice(cfqq); 2284 cfq_clear_cfqq_fifo_expire(cfqq); 2285 cfq_mark_cfqq_slice_new(cfqq); 2286 2287 cfq_del_timer(cfqd, cfqq); 2288 } 2289 2290 cfqd->active_queue = cfqq; 2291} 2292 2293/* 2294 * current cfqq expired its slice (or was too idle), select new one 2295 */ 2296static void 2297__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2298 bool timed_out) 2299{ 2300 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 2301 2302 if (cfq_cfqq_wait_request(cfqq)) 2303 cfq_del_timer(cfqd, cfqq); 2304 2305 cfq_clear_cfqq_wait_request(cfqq); 2306 cfq_clear_cfqq_wait_busy(cfqq); 2307 2308 /* 2309 * If this cfqq is shared between multiple processes, check to 2310 * make sure that those processes are still issuing I/Os within 2311 * the mean seek distance. If not, it may be time to break the 2312 * queues apart again. 2313 */ 2314 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 2315 cfq_mark_cfqq_split_coop(cfqq); 2316 2317 /* 2318 * store what was left of this slice, if the queue idled/timed out 2319 */ 2320 if (timed_out) { 2321 if (cfq_cfqq_slice_new(cfqq)) 2322 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 2323 else 2324 cfqq->slice_resid = cfqq->slice_end - jiffies; 2325 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 2326 } 2327 2328 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 2329 2330 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 2331 cfq_del_cfqq_rr(cfqd, cfqq); 2332 2333 cfq_resort_rr_list(cfqd, cfqq); 2334 2335 if (cfqq == cfqd->active_queue) 2336 cfqd->active_queue = NULL; 2337 2338 if (cfqd->active_cic) { 2339 put_io_context(cfqd->active_cic->icq.ioc); 2340 cfqd->active_cic = NULL; 2341 } 2342} 2343 2344static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 2345{ 2346 struct cfq_queue *cfqq = cfqd->active_queue; 2347 2348 if (cfqq) 2349 __cfq_slice_expired(cfqd, cfqq, timed_out); 2350} 2351 2352/* 2353 * Get next queue for service. Unless we have a queue preemption, 2354 * we'll simply select the first cfqq in the service tree. 2355 */ 2356static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 2357{ 2358 struct cfq_rb_root *st = st_for(cfqd->serving_group, 2359 cfqd->serving_wl_class, cfqd->serving_wl_type); 2360 2361 if (!cfqd->rq_queued) 2362 return NULL; 2363 2364 /* There is nothing to dispatch */ 2365 if (!st) 2366 return NULL; 2367 if (RB_EMPTY_ROOT(&st->rb)) 2368 return NULL; 2369 return cfq_rb_first(st); 2370} 2371 2372static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 2373{ 2374 struct cfq_group *cfqg; 2375 struct cfq_queue *cfqq; 2376 int i, j; 2377 struct cfq_rb_root *st; 2378 2379 if (!cfqd->rq_queued) 2380 return NULL; 2381 2382 cfqg = cfq_get_next_cfqg(cfqd); 2383 if (!cfqg) 2384 return NULL; 2385 2386 for_each_cfqg_st(cfqg, i, j, st) 2387 if ((cfqq = cfq_rb_first(st)) != NULL) 2388 return cfqq; 2389 return NULL; 2390} 2391 2392/* 2393 * Get and set a new active queue for service. 2394 */ 2395static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 2396 struct cfq_queue *cfqq) 2397{ 2398 if (!cfqq) 2399 cfqq = cfq_get_next_queue(cfqd); 2400 2401 __cfq_set_active_queue(cfqd, cfqq); 2402 return cfqq; 2403} 2404 2405static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 2406 struct request *rq) 2407{ 2408 if (blk_rq_pos(rq) >= cfqd->last_position) 2409 return blk_rq_pos(rq) - cfqd->last_position; 2410 else 2411 return cfqd->last_position - blk_rq_pos(rq); 2412} 2413 2414static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2415 struct request *rq) 2416{ 2417 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 2418} 2419 2420static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 2421 struct cfq_queue *cur_cfqq) 2422{ 2423 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 2424 struct rb_node *parent, *node; 2425 struct cfq_queue *__cfqq; 2426 sector_t sector = cfqd->last_position; 2427 2428 if (RB_EMPTY_ROOT(root)) 2429 return NULL; 2430 2431 /* 2432 * First, if we find a request starting at the end of the last 2433 * request, choose it. 2434 */ 2435 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 2436 if (__cfqq) 2437 return __cfqq; 2438 2439 /* 2440 * If the exact sector wasn't found, the parent of the NULL leaf 2441 * will contain the closest sector. 2442 */ 2443 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 2444 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2445 return __cfqq; 2446 2447 if (blk_rq_pos(__cfqq->next_rq) < sector) 2448 node = rb_next(&__cfqq->p_node); 2449 else 2450 node = rb_prev(&__cfqq->p_node); 2451 if (!node) 2452 return NULL; 2453 2454 __cfqq = rb_entry(node, struct cfq_queue, p_node); 2455 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 2456 return __cfqq; 2457 2458 return NULL; 2459} 2460 2461/* 2462 * cfqd - obvious 2463 * cur_cfqq - passed in so that we don't decide that the current queue is 2464 * closely cooperating with itself. 2465 * 2466 * So, basically we're assuming that that cur_cfqq has dispatched at least 2467 * one request, and that cfqd->last_position reflects a position on the disk 2468 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 2469 * assumption. 2470 */ 2471static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 2472 struct cfq_queue *cur_cfqq) 2473{ 2474 struct cfq_queue *cfqq; 2475 2476 if (cfq_class_idle(cur_cfqq)) 2477 return NULL; 2478 if (!cfq_cfqq_sync(cur_cfqq)) 2479 return NULL; 2480 if (CFQQ_SEEKY(cur_cfqq)) 2481 return NULL; 2482 2483 /* 2484 * Don't search priority tree if it's the only queue in the group. 2485 */ 2486 if (cur_cfqq->cfqg->nr_cfqq == 1) 2487 return NULL; 2488 2489 /* 2490 * We should notice if some of the queues are cooperating, eg 2491 * working closely on the same area of the disk. In that case, 2492 * we can group them together and don't waste time idling. 2493 */ 2494 cfqq = cfqq_close(cfqd, cur_cfqq); 2495 if (!cfqq) 2496 return NULL; 2497 2498 /* If new queue belongs to different cfq_group, don't choose it */ 2499 if (cur_cfqq->cfqg != cfqq->cfqg) 2500 return NULL; 2501 2502 /* 2503 * It only makes sense to merge sync queues. 2504 */ 2505 if (!cfq_cfqq_sync(cfqq)) 2506 return NULL; 2507 if (CFQQ_SEEKY(cfqq)) 2508 return NULL; 2509 2510 /* 2511 * Do not merge queues of different priority classes 2512 */ 2513 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 2514 return NULL; 2515 2516 return cfqq; 2517} 2518 2519/* 2520 * Determine whether we should enforce idle window for this queue. 2521 */ 2522 2523static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2524{ 2525 enum wl_class_t wl_class = cfqq_class(cfqq); 2526 struct cfq_rb_root *st = cfqq->service_tree; 2527 2528 BUG_ON(!st); 2529 BUG_ON(!st->count); 2530 2531 if (!cfqd->cfq_slice_idle) 2532 return false; 2533 2534 /* We never do for idle class queues. */ 2535 if (wl_class == IDLE_WORKLOAD) 2536 return false; 2537 2538 /* We do for queues that were marked with idle window flag. */ 2539 if (cfq_cfqq_idle_window(cfqq) && 2540 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 2541 return true; 2542 2543 /* 2544 * Otherwise, we do only if they are the last ones 2545 * in their service tree. 2546 */ 2547 if (st->count == 1 && cfq_cfqq_sync(cfqq) && 2548 !cfq_io_thinktime_big(cfqd, &st->ttime, false)) 2549 return true; 2550 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count); 2551 return false; 2552} 2553 2554static void cfq_arm_slice_timer(struct cfq_data *cfqd) 2555{ 2556 struct cfq_queue *cfqq = cfqd->active_queue; 2557 struct cfq_io_cq *cic; 2558 unsigned long sl, group_idle = 0; 2559 2560 /* 2561 * SSD device without seek penalty, disable idling. But only do so 2562 * for devices that support queuing, otherwise we still have a problem 2563 * with sync vs async workloads. 2564 */ 2565 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 2566 return; 2567 2568 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 2569 WARN_ON(cfq_cfqq_slice_new(cfqq)); 2570 2571 /* 2572 * idle is disabled, either manually or by past process history 2573 */ 2574 if (!cfq_should_idle(cfqd, cfqq)) { 2575 /* no queue idling. Check for group idling */ 2576 if (cfqd->cfq_group_idle) 2577 group_idle = cfqd->cfq_group_idle; 2578 else 2579 return; 2580 } 2581 2582 /* 2583 * still active requests from this queue, don't idle 2584 */ 2585 if (cfqq->dispatched) 2586 return; 2587 2588 /* 2589 * task has exited, don't wait 2590 */ 2591 cic = cfqd->active_cic; 2592 if (!cic || !atomic_read(&cic->icq.ioc->active_ref)) 2593 return; 2594 2595 /* 2596 * If our average think time is larger than the remaining time 2597 * slice, then don't idle. This avoids overrunning the allotted 2598 * time slice. 2599 */ 2600 if (sample_valid(cic->ttime.ttime_samples) && 2601 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { 2602 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", 2603 cic->ttime.ttime_mean); 2604 return; 2605 } 2606 2607 /* There are other queues in the group, don't do group idle */ 2608 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2609 return; 2610 2611 cfq_mark_cfqq_wait_request(cfqq); 2612 2613 if (group_idle) 2614 sl = cfqd->cfq_group_idle; 2615 else 2616 sl = cfqd->cfq_slice_idle; 2617 2618 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2619 cfqg_stats_set_start_idle_time(cfqq->cfqg); 2620 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2621 group_idle ? 1 : 0); 2622} 2623 2624/* 2625 * Move request from internal lists to the request queue dispatch list. 2626 */ 2627static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2628{ 2629 struct cfq_data *cfqd = q->elevator->elevator_data; 2630 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2631 2632 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2633 2634 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2635 cfq_remove_request(rq); 2636 cfqq->dispatched++; 2637 (RQ_CFQG(rq))->dispatched++; 2638 elv_dispatch_sort(q, rq); 2639 2640 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2641 cfqq->nr_sectors += blk_rq_sectors(rq); 2642 cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags); 2643} 2644 2645/* 2646 * return expired entry, or NULL to just start from scratch in rbtree 2647 */ 2648static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2649{ 2650 struct request *rq = NULL; 2651 2652 if (cfq_cfqq_fifo_expire(cfqq)) 2653 return NULL; 2654 2655 cfq_mark_cfqq_fifo_expire(cfqq); 2656 2657 if (list_empty(&cfqq->fifo)) 2658 return NULL; 2659 2660 rq = rq_entry_fifo(cfqq->fifo.next); 2661 if (time_before(jiffies, rq_fifo_time(rq))) 2662 rq = NULL; 2663 2664 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2665 return rq; 2666} 2667 2668static inline int 2669cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2670{ 2671 const int base_rq = cfqd->cfq_slice_async_rq; 2672 2673 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2674 2675 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); 2676} 2677 2678/* 2679 * Must be called with the queue_lock held. 2680 */ 2681static int cfqq_process_refs(struct cfq_queue *cfqq) 2682{ 2683 int process_refs, io_refs; 2684 2685 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2686 process_refs = cfqq->ref - io_refs; 2687 BUG_ON(process_refs < 0); 2688 return process_refs; 2689} 2690 2691static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2692{ 2693 int process_refs, new_process_refs; 2694 struct cfq_queue *__cfqq; 2695 2696 /* 2697 * If there are no process references on the new_cfqq, then it is 2698 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2699 * chain may have dropped their last reference (not just their 2700 * last process reference). 2701 */ 2702 if (!cfqq_process_refs(new_cfqq)) 2703 return; 2704 2705 /* Avoid a circular list and skip interim queue merges */ 2706 while ((__cfqq = new_cfqq->new_cfqq)) { 2707 if (__cfqq == cfqq) 2708 return; 2709 new_cfqq = __cfqq; 2710 } 2711 2712 process_refs = cfqq_process_refs(cfqq); 2713 new_process_refs = cfqq_process_refs(new_cfqq); 2714 /* 2715 * If the process for the cfqq has gone away, there is no 2716 * sense in merging the queues. 2717 */ 2718 if (process_refs == 0 || new_process_refs == 0) 2719 return; 2720 2721 /* 2722 * Merge in the direction of the lesser amount of work. 2723 */ 2724 if (new_process_refs >= process_refs) { 2725 cfqq->new_cfqq = new_cfqq; 2726 new_cfqq->ref += process_refs; 2727 } else { 2728 new_cfqq->new_cfqq = cfqq; 2729 cfqq->ref += new_process_refs; 2730 } 2731} 2732 2733static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd, 2734 struct cfq_group *cfqg, enum wl_class_t wl_class) 2735{ 2736 struct cfq_queue *queue; 2737 int i; 2738 bool key_valid = false; 2739 unsigned long lowest_key = 0; 2740 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2741 2742 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2743 /* select the one with lowest rb_key */ 2744 queue = cfq_rb_first(st_for(cfqg, wl_class, i)); 2745 if (queue && 2746 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2747 lowest_key = queue->rb_key; 2748 cur_best = i; 2749 key_valid = true; 2750 } 2751 } 2752 2753 return cur_best; 2754} 2755 2756static void 2757choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg) 2758{ 2759 unsigned slice; 2760 unsigned count; 2761 struct cfq_rb_root *st; 2762 unsigned group_slice; 2763 enum wl_class_t original_class = cfqd->serving_wl_class; 2764 2765 /* Choose next priority. RT > BE > IDLE */ 2766 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2767 cfqd->serving_wl_class = RT_WORKLOAD; 2768 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2769 cfqd->serving_wl_class = BE_WORKLOAD; 2770 else { 2771 cfqd->serving_wl_class = IDLE_WORKLOAD; 2772 cfqd->workload_expires = jiffies + 1; 2773 return; 2774 } 2775 2776 if (original_class != cfqd->serving_wl_class) 2777 goto new_workload; 2778 2779 /* 2780 * For RT and BE, we have to choose also the type 2781 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2782 * expiration time 2783 */ 2784 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type); 2785 count = st->count; 2786 2787 /* 2788 * check workload expiration, and that we still have other queues ready 2789 */ 2790 if (count && !time_after(jiffies, cfqd->workload_expires)) 2791 return; 2792 2793new_workload: 2794 /* otherwise select new workload type */ 2795 cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg, 2796 cfqd->serving_wl_class); 2797 st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type); 2798 count = st->count; 2799 2800 /* 2801 * the workload slice is computed as a fraction of target latency 2802 * proportional to the number of queues in that workload, over 2803 * all the queues in the same priority class 2804 */ 2805 group_slice = cfq_group_slice(cfqd, cfqg); 2806 2807 slice = group_slice * count / 2808 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class], 2809 cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd, 2810 cfqg)); 2811 2812 if (cfqd->serving_wl_type == ASYNC_WORKLOAD) { 2813 unsigned int tmp; 2814 2815 /* 2816 * Async queues are currently system wide. Just taking 2817 * proportion of queues with-in same group will lead to higher 2818 * async ratio system wide as generally root group is going 2819 * to have higher weight. A more accurate thing would be to 2820 * calculate system wide asnc/sync ratio. 2821 */ 2822 tmp = cfqd->cfq_target_latency * 2823 cfqg_busy_async_queues(cfqd, cfqg); 2824 tmp = tmp/cfqd->busy_queues; 2825 slice = min_t(unsigned, slice, tmp); 2826 2827 /* async workload slice is scaled down according to 2828 * the sync/async slice ratio. */ 2829 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2830 } else 2831 /* sync workload slice is at least 2 * cfq_slice_idle */ 2832 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2833 2834 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2835 cfq_log(cfqd, "workload slice:%d", slice); 2836 cfqd->workload_expires = jiffies + slice; 2837} 2838 2839static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2840{ 2841 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2842 struct cfq_group *cfqg; 2843 2844 if (RB_EMPTY_ROOT(&st->rb)) 2845 return NULL; 2846 cfqg = cfq_rb_first_group(st); 2847 update_min_vdisktime(st); 2848 return cfqg; 2849} 2850 2851static void cfq_choose_cfqg(struct cfq_data *cfqd) 2852{ 2853 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2854 2855 cfqd->serving_group = cfqg; 2856 2857 /* Restore the workload type data */ 2858 if (cfqg->saved_wl_slice) { 2859 cfqd->workload_expires = jiffies + cfqg->saved_wl_slice; 2860 cfqd->serving_wl_type = cfqg->saved_wl_type; 2861 cfqd->serving_wl_class = cfqg->saved_wl_class; 2862 } else 2863 cfqd->workload_expires = jiffies - 1; 2864 2865 choose_wl_class_and_type(cfqd, cfqg); 2866} 2867 2868/* 2869 * Select a queue for service. If we have a current active queue, 2870 * check whether to continue servicing it, or retrieve and set a new one. 2871 */ 2872static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2873{ 2874 struct cfq_queue *cfqq, *new_cfqq = NULL; 2875 2876 cfqq = cfqd->active_queue; 2877 if (!cfqq) 2878 goto new_queue; 2879 2880 if (!cfqd->rq_queued) 2881 return NULL; 2882 2883 /* 2884 * We were waiting for group to get backlogged. Expire the queue 2885 */ 2886 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2887 goto expire; 2888 2889 /* 2890 * The active queue has run out of time, expire it and select new. 2891 */ 2892 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2893 /* 2894 * If slice had not expired at the completion of last request 2895 * we might not have turned on wait_busy flag. Don't expire 2896 * the queue yet. Allow the group to get backlogged. 2897 * 2898 * The very fact that we have used the slice, that means we 2899 * have been idling all along on this queue and it should be 2900 * ok to wait for this request to complete. 2901 */ 2902 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2903 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2904 cfqq = NULL; 2905 goto keep_queue; 2906 } else 2907 goto check_group_idle; 2908 } 2909 2910 /* 2911 * The active queue has requests and isn't expired, allow it to 2912 * dispatch. 2913 */ 2914 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2915 goto keep_queue; 2916 2917 /* 2918 * If another queue has a request waiting within our mean seek 2919 * distance, let it run. The expire code will check for close 2920 * cooperators and put the close queue at the front of the service 2921 * tree. If possible, merge the expiring queue with the new cfqq. 2922 */ 2923 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2924 if (new_cfqq) { 2925 if (!cfqq->new_cfqq) 2926 cfq_setup_merge(cfqq, new_cfqq); 2927 goto expire; 2928 } 2929 2930 /* 2931 * No requests pending. If the active queue still has requests in 2932 * flight or is idling for a new request, allow either of these 2933 * conditions to happen (or time out) before selecting a new queue. 2934 */ 2935 if (timer_pending(&cfqd->idle_slice_timer)) { 2936 cfqq = NULL; 2937 goto keep_queue; 2938 } 2939 2940 /* 2941 * This is a deep seek queue, but the device is much faster than 2942 * the queue can deliver, don't idle 2943 **/ 2944 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2945 (cfq_cfqq_slice_new(cfqq) || 2946 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2947 cfq_clear_cfqq_deep(cfqq); 2948 cfq_clear_cfqq_idle_window(cfqq); 2949 } 2950 2951 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2952 cfqq = NULL; 2953 goto keep_queue; 2954 } 2955 2956 /* 2957 * If group idle is enabled and there are requests dispatched from 2958 * this group, wait for requests to complete. 2959 */ 2960check_group_idle: 2961 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && 2962 cfqq->cfqg->dispatched && 2963 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { 2964 cfqq = NULL; 2965 goto keep_queue; 2966 } 2967 2968expire: 2969 cfq_slice_expired(cfqd, 0); 2970new_queue: 2971 /* 2972 * Current queue expired. Check if we have to switch to a new 2973 * service tree 2974 */ 2975 if (!new_cfqq) 2976 cfq_choose_cfqg(cfqd); 2977 2978 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2979keep_queue: 2980 return cfqq; 2981} 2982 2983static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2984{ 2985 int dispatched = 0; 2986 2987 while (cfqq->next_rq) { 2988 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2989 dispatched++; 2990 } 2991 2992 BUG_ON(!list_empty(&cfqq->fifo)); 2993 2994 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2995 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2996 return dispatched; 2997} 2998 2999/* 3000 * Drain our current requests. Used for barriers and when switching 3001 * io schedulers on-the-fly. 3002 */ 3003static int cfq_forced_dispatch(struct cfq_data *cfqd) 3004{ 3005 struct cfq_queue *cfqq; 3006 int dispatched = 0; 3007 3008 /* Expire the timeslice of the current active queue first */ 3009 cfq_slice_expired(cfqd, 0); 3010 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 3011 __cfq_set_active_queue(cfqd, cfqq); 3012 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 3013 } 3014 3015 BUG_ON(cfqd->busy_queues); 3016 3017 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 3018 return dispatched; 3019} 3020 3021static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 3022 struct cfq_queue *cfqq) 3023{ 3024 /* the queue hasn't finished any request, can't estimate */ 3025 if (cfq_cfqq_slice_new(cfqq)) 3026 return true; 3027 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 3028 cfqq->slice_end)) 3029 return true; 3030 3031 return false; 3032} 3033 3034static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3035{ 3036 unsigned int max_dispatch; 3037 3038 /* 3039 * Drain async requests before we start sync IO 3040 */ 3041 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 3042 return false; 3043 3044 /* 3045 * If this is an async queue and we have sync IO in flight, let it wait 3046 */ 3047 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 3048 return false; 3049 3050 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 3051 if (cfq_class_idle(cfqq)) 3052 max_dispatch = 1; 3053 3054 /* 3055 * Does this cfqq already have too much IO in flight? 3056 */ 3057 if (cfqq->dispatched >= max_dispatch) { 3058 bool promote_sync = false; 3059 /* 3060 * idle queue must always only have a single IO in flight 3061 */ 3062 if (cfq_class_idle(cfqq)) 3063 return false; 3064 3065 /* 3066 * If there is only one sync queue 3067 * we can ignore async queue here and give the sync 3068 * queue no dispatch limit. The reason is a sync queue can 3069 * preempt async queue, limiting the sync queue doesn't make 3070 * sense. This is useful for aiostress test. 3071 */ 3072 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 3073 promote_sync = true; 3074 3075 /* 3076 * We have other queues, don't allow more IO from this one 3077 */ 3078 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 3079 !promote_sync) 3080 return false; 3081 3082 /* 3083 * Sole queue user, no limit 3084 */ 3085 if (cfqd->busy_queues == 1 || promote_sync) 3086 max_dispatch = -1; 3087 else 3088 /* 3089 * Normally we start throttling cfqq when cfq_quantum/2 3090 * requests have been dispatched. But we can drive 3091 * deeper queue depths at the beginning of slice 3092 * subjected to upper limit of cfq_quantum. 3093 * */ 3094 max_dispatch = cfqd->cfq_quantum; 3095 } 3096 3097 /* 3098 * Async queues must wait a bit before being allowed dispatch. 3099 * We also ramp up the dispatch depth gradually for async IO, 3100 * based on the last sync IO we serviced 3101 */ 3102 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 3103 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 3104 unsigned int depth; 3105 3106 depth = last_sync / cfqd->cfq_slice[1]; 3107 if (!depth && !cfqq->dispatched) 3108 depth = 1; 3109 if (depth < max_dispatch) 3110 max_dispatch = depth; 3111 } 3112 3113 /* 3114 * If we're below the current max, allow a dispatch 3115 */ 3116 return cfqq->dispatched < max_dispatch; 3117} 3118 3119/* 3120 * Dispatch a request from cfqq, moving them to the request queue 3121 * dispatch list. 3122 */ 3123static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3124{ 3125 struct request *rq; 3126 3127 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 3128 3129 if (!cfq_may_dispatch(cfqd, cfqq)) 3130 return false; 3131 3132 /* 3133 * follow expired path, else get first next available 3134 */ 3135 rq = cfq_check_fifo(cfqq); 3136 if (!rq) 3137 rq = cfqq->next_rq; 3138 3139 /* 3140 * insert request into driver dispatch list 3141 */ 3142 cfq_dispatch_insert(cfqd->queue, rq); 3143 3144 if (!cfqd->active_cic) { 3145 struct cfq_io_cq *cic = RQ_CIC(rq); 3146 3147 atomic_long_inc(&cic->icq.ioc->refcount); 3148 cfqd->active_cic = cic; 3149 } 3150 3151 return true; 3152} 3153 3154/* 3155 * Find the cfqq that we need to service and move a request from that to the 3156 * dispatch list 3157 */ 3158static int cfq_dispatch_requests(struct request_queue *q, int force) 3159{ 3160 struct cfq_data *cfqd = q->elevator->elevator_data; 3161 struct cfq_queue *cfqq; 3162 3163 if (!cfqd->busy_queues) 3164 return 0; 3165 3166 if (unlikely(force)) 3167 return cfq_forced_dispatch(cfqd); 3168 3169 cfqq = cfq_select_queue(cfqd); 3170 if (!cfqq) 3171 return 0; 3172 3173 /* 3174 * Dispatch a request from this cfqq, if it is allowed 3175 */ 3176 if (!cfq_dispatch_request(cfqd, cfqq)) 3177 return 0; 3178 3179 cfqq->slice_dispatch++; 3180 cfq_clear_cfqq_must_dispatch(cfqq); 3181 3182 /* 3183 * expire an async queue immediately if it has used up its slice. idle 3184 * queue always expire after 1 dispatch round. 3185 */ 3186 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 3187 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 3188 cfq_class_idle(cfqq))) { 3189 cfqq->slice_end = jiffies + 1; 3190 cfq_slice_expired(cfqd, 0); 3191 } 3192 3193 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 3194 return 1; 3195} 3196 3197/* 3198 * task holds one reference to the queue, dropped when task exits. each rq 3199 * in-flight on this queue also holds a reference, dropped when rq is freed. 3200 * 3201 * Each cfq queue took a reference on the parent group. Drop it now. 3202 * queue lock must be held here. 3203 */ 3204static void cfq_put_queue(struct cfq_queue *cfqq) 3205{ 3206 struct cfq_data *cfqd = cfqq->cfqd; 3207 struct cfq_group *cfqg; 3208 3209 BUG_ON(cfqq->ref <= 0); 3210 3211 cfqq->ref--; 3212 if (cfqq->ref) 3213 return; 3214 3215 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 3216 BUG_ON(rb_first(&cfqq->sort_list)); 3217 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 3218 cfqg = cfqq->cfqg; 3219 3220 if (unlikely(cfqd->active_queue == cfqq)) { 3221 __cfq_slice_expired(cfqd, cfqq, 0); 3222 cfq_schedule_dispatch(cfqd); 3223 } 3224 3225 BUG_ON(cfq_cfqq_on_rr(cfqq)); 3226 kmem_cache_free(cfq_pool, cfqq); 3227 cfqg_put(cfqg); 3228} 3229 3230static void cfq_put_cooperator(struct cfq_queue *cfqq) 3231{ 3232 struct cfq_queue *__cfqq, *next; 3233 3234 /* 3235 * If this queue was scheduled to merge with another queue, be 3236 * sure to drop the reference taken on that queue (and others in 3237 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 3238 */ 3239 __cfqq = cfqq->new_cfqq; 3240 while (__cfqq) { 3241 if (__cfqq == cfqq) { 3242 WARN(1, "cfqq->new_cfqq loop detected\n"); 3243 break; 3244 } 3245 next = __cfqq->new_cfqq; 3246 cfq_put_queue(__cfqq); 3247 __cfqq = next; 3248 } 3249} 3250 3251static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3252{ 3253 if (unlikely(cfqq == cfqd->active_queue)) { 3254 __cfq_slice_expired(cfqd, cfqq, 0); 3255 cfq_schedule_dispatch(cfqd); 3256 } 3257 3258 cfq_put_cooperator(cfqq); 3259 3260 cfq_put_queue(cfqq); 3261} 3262 3263static void cfq_init_icq(struct io_cq *icq) 3264{ 3265 struct cfq_io_cq *cic = icq_to_cic(icq); 3266 3267 cic->ttime.last_end_request = jiffies; 3268} 3269 3270static void cfq_exit_icq(struct io_cq *icq) 3271{ 3272 struct cfq_io_cq *cic = icq_to_cic(icq); 3273 struct cfq_data *cfqd = cic_to_cfqd(cic); 3274 3275 if (cic->cfqq[BLK_RW_ASYNC]) { 3276 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 3277 cic->cfqq[BLK_RW_ASYNC] = NULL; 3278 } 3279 3280 if (cic->cfqq[BLK_RW_SYNC]) { 3281 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 3282 cic->cfqq[BLK_RW_SYNC] = NULL; 3283 } 3284} 3285 3286static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic) 3287{ 3288 struct task_struct *tsk = current; 3289 int ioprio_class; 3290 3291 if (!cfq_cfqq_prio_changed(cfqq)) 3292 return; 3293 3294 ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3295 switch (ioprio_class) { 3296 default: 3297 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 3298 case IOPRIO_CLASS_NONE: 3299 /* 3300 * no prio set, inherit CPU scheduling settings 3301 */ 3302 cfqq->ioprio = task_nice_ioprio(tsk); 3303 cfqq->ioprio_class = task_nice_ioclass(tsk); 3304 break; 3305 case IOPRIO_CLASS_RT: 3306 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3307 cfqq->ioprio_class = IOPRIO_CLASS_RT; 3308 break; 3309 case IOPRIO_CLASS_BE: 3310 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3311 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3312 break; 3313 case IOPRIO_CLASS_IDLE: 3314 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 3315 cfqq->ioprio = 7; 3316 cfq_clear_cfqq_idle_window(cfqq); 3317 break; 3318 } 3319 3320 /* 3321 * keep track of original prio settings in case we have to temporarily 3322 * elevate the priority of this queue 3323 */ 3324 cfqq->org_ioprio = cfqq->ioprio; 3325 cfq_clear_cfqq_prio_changed(cfqq); 3326} 3327 3328static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio) 3329{ 3330 int ioprio = cic->icq.ioc->ioprio; 3331 struct cfq_data *cfqd = cic_to_cfqd(cic); 3332 struct cfq_queue *cfqq; 3333 3334 /* 3335 * Check whether ioprio has changed. The condition may trigger 3336 * spuriously on a newly created cic but there's no harm. 3337 */ 3338 if (unlikely(!cfqd) || likely(cic->ioprio == ioprio)) 3339 return; 3340 3341 cfqq = cic->cfqq[BLK_RW_ASYNC]; 3342 if (cfqq) { 3343 struct cfq_queue *new_cfqq; 3344 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio, 3345 GFP_ATOMIC); 3346 if (new_cfqq) { 3347 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 3348 cfq_put_queue(cfqq); 3349 } 3350 } 3351 3352 cfqq = cic->cfqq[BLK_RW_SYNC]; 3353 if (cfqq) 3354 cfq_mark_cfqq_prio_changed(cfqq); 3355 3356 cic->ioprio = ioprio; 3357} 3358 3359static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3360 pid_t pid, bool is_sync) 3361{ 3362 RB_CLEAR_NODE(&cfqq->rb_node); 3363 RB_CLEAR_NODE(&cfqq->p_node); 3364 INIT_LIST_HEAD(&cfqq->fifo); 3365 3366 cfqq->ref = 0; 3367 cfqq->cfqd = cfqd; 3368 3369 cfq_mark_cfqq_prio_changed(cfqq); 3370 3371 if (is_sync) { 3372 if (!cfq_class_idle(cfqq)) 3373 cfq_mark_cfqq_idle_window(cfqq); 3374 cfq_mark_cfqq_sync(cfqq); 3375 } 3376 cfqq->pid = pid; 3377} 3378 3379#ifdef CONFIG_CFQ_GROUP_IOSCHED 3380static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) 3381{ 3382 struct cfq_data *cfqd = cic_to_cfqd(cic); 3383 struct cfq_queue *sync_cfqq; 3384 uint64_t id; 3385 3386 rcu_read_lock(); 3387 id = bio_blkcg(bio)->id; 3388 rcu_read_unlock(); 3389 3390 /* 3391 * Check whether blkcg has changed. The condition may trigger 3392 * spuriously on a newly created cic but there's no harm. 3393 */ 3394 if (unlikely(!cfqd) || likely(cic->blkcg_id == id)) 3395 return; 3396 3397 sync_cfqq = cic_to_cfqq(cic, 1); 3398 if (sync_cfqq) { 3399 /* 3400 * Drop reference to sync queue. A new sync queue will be 3401 * assigned in new group upon arrival of a fresh request. 3402 */ 3403 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 3404 cic_set_cfqq(cic, NULL, 1); 3405 cfq_put_queue(sync_cfqq); 3406 } 3407 3408 cic->blkcg_id = id; 3409} 3410#else 3411static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { } 3412#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 3413 3414static struct cfq_queue * 3415cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3416 struct bio *bio, gfp_t gfp_mask) 3417{ 3418 struct blkcg *blkcg; 3419 struct cfq_queue *cfqq, *new_cfqq = NULL; 3420 struct cfq_group *cfqg; 3421 3422retry: 3423 rcu_read_lock(); 3424 3425 blkcg = bio_blkcg(bio); 3426 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg); 3427 cfqq = cic_to_cfqq(cic, is_sync); 3428 3429 /* 3430 * Always try a new alloc if we fell back to the OOM cfqq 3431 * originally, since it should just be a temporary situation. 3432 */ 3433 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3434 cfqq = NULL; 3435 if (new_cfqq) { 3436 cfqq = new_cfqq; 3437 new_cfqq = NULL; 3438 } else if (gfp_mask & __GFP_WAIT) { 3439 rcu_read_unlock(); 3440 spin_unlock_irq(cfqd->queue->queue_lock); 3441 new_cfqq = kmem_cache_alloc_node(cfq_pool, 3442 gfp_mask | __GFP_ZERO, 3443 cfqd->queue->node); 3444 spin_lock_irq(cfqd->queue->queue_lock); 3445 if (new_cfqq) 3446 goto retry; 3447 } else { 3448 cfqq = kmem_cache_alloc_node(cfq_pool, 3449 gfp_mask | __GFP_ZERO, 3450 cfqd->queue->node); 3451 } 3452 3453 if (cfqq) { 3454 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3455 cfq_init_prio_data(cfqq, cic); 3456 cfq_link_cfqq_cfqg(cfqq, cfqg); 3457 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3458 } else 3459 cfqq = &cfqd->oom_cfqq; 3460 } 3461 3462 if (new_cfqq) 3463 kmem_cache_free(cfq_pool, new_cfqq); 3464 3465 rcu_read_unlock(); 3466 return cfqq; 3467} 3468 3469static struct cfq_queue ** 3470cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3471{ 3472 switch (ioprio_class) { 3473 case IOPRIO_CLASS_RT: 3474 return &cfqd->async_cfqq[0][ioprio]; 3475 case IOPRIO_CLASS_NONE: 3476 ioprio = IOPRIO_NORM; 3477 /* fall through */ 3478 case IOPRIO_CLASS_BE: 3479 return &cfqd->async_cfqq[1][ioprio]; 3480 case IOPRIO_CLASS_IDLE: 3481 return &cfqd->async_idle_cfqq; 3482 default: 3483 BUG(); 3484 } 3485} 3486 3487static struct cfq_queue * 3488cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, 3489 struct bio *bio, gfp_t gfp_mask) 3490{ 3491 const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); 3492 const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); 3493 struct cfq_queue **async_cfqq = NULL; 3494 struct cfq_queue *cfqq = NULL; 3495 3496 if (!is_sync) { 3497 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3498 cfqq = *async_cfqq; 3499 } 3500 3501 if (!cfqq) 3502 cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask); 3503 3504 /* 3505 * pin the queue now that it's allocated, scheduler exit will prune it 3506 */ 3507 if (!is_sync && !(*async_cfqq)) { 3508 cfqq->ref++; 3509 *async_cfqq = cfqq; 3510 } 3511 3512 cfqq->ref++; 3513 return cfqq; 3514} 3515 3516static void 3517__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) 3518{ 3519 unsigned long elapsed = jiffies - ttime->last_end_request; 3520 elapsed = min(elapsed, 2UL * slice_idle); 3521 3522 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; 3523 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; 3524 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; 3525} 3526 3527static void 3528cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3529 struct cfq_io_cq *cic) 3530{ 3531 if (cfq_cfqq_sync(cfqq)) { 3532 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); 3533 __cfq_update_io_thinktime(&cfqq->service_tree->ttime, 3534 cfqd->cfq_slice_idle); 3535 } 3536#ifdef CONFIG_CFQ_GROUP_IOSCHED 3537 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); 3538#endif 3539} 3540 3541static void 3542cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3543 struct request *rq) 3544{ 3545 sector_t sdist = 0; 3546 sector_t n_sec = blk_rq_sectors(rq); 3547 if (cfqq->last_request_pos) { 3548 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3549 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3550 else 3551 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3552 } 3553 3554 cfqq->seek_history <<= 1; 3555 if (blk_queue_nonrot(cfqd->queue)) 3556 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3557 else 3558 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3559} 3560 3561/* 3562 * Disable idle window if the process thinks too long or seeks so much that 3563 * it doesn't matter 3564 */ 3565static void 3566cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3567 struct cfq_io_cq *cic) 3568{ 3569 int old_idle, enable_idle; 3570 3571 /* 3572 * Don't idle for async or idle io prio class 3573 */ 3574 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3575 return; 3576 3577 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3578 3579 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3580 cfq_mark_cfqq_deep(cfqq); 3581 3582 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3583 enable_idle = 0; 3584 else if (!atomic_read(&cic->icq.ioc->active_ref) || 3585 !cfqd->cfq_slice_idle || 3586 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3587 enable_idle = 0; 3588 else if (sample_valid(cic->ttime.ttime_samples)) { 3589 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) 3590 enable_idle = 0; 3591 else 3592 enable_idle = 1; 3593 } 3594 3595 if (old_idle != enable_idle) { 3596 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3597 if (enable_idle) 3598 cfq_mark_cfqq_idle_window(cfqq); 3599 else 3600 cfq_clear_cfqq_idle_window(cfqq); 3601 } 3602} 3603 3604/* 3605 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3606 * no or if we aren't sure, a 1 will cause a preempt. 3607 */ 3608static bool 3609cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3610 struct request *rq) 3611{ 3612 struct cfq_queue *cfqq; 3613 3614 cfqq = cfqd->active_queue; 3615 if (!cfqq) 3616 return false; 3617 3618 if (cfq_class_idle(new_cfqq)) 3619 return false; 3620 3621 if (cfq_class_idle(cfqq)) 3622 return true; 3623 3624 /* 3625 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3626 */ 3627 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3628 return false; 3629 3630 /* 3631 * if the new request is sync, but the currently running queue is 3632 * not, let the sync request have priority. 3633 */ 3634 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3635 return true; 3636 3637 if (new_cfqq->cfqg != cfqq->cfqg) 3638 return false; 3639 3640 if (cfq_slice_used(cfqq)) 3641 return true; 3642 3643 /* Allow preemption only if we are idling on sync-noidle tree */ 3644 if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD && 3645 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3646 new_cfqq->service_tree->count == 2 && 3647 RB_EMPTY_ROOT(&cfqq->sort_list)) 3648 return true; 3649 3650 /* 3651 * So both queues are sync. Let the new request get disk time if 3652 * it's a metadata request and the current queue is doing regular IO. 3653 */ 3654 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) 3655 return true; 3656 3657 /* 3658 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3659 */ 3660 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3661 return true; 3662 3663 /* An idle queue should not be idle now for some reason */ 3664 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3665 return true; 3666 3667 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3668 return false; 3669 3670 /* 3671 * if this request is as-good as one we would expect from the 3672 * current cfqq, let it preempt 3673 */ 3674 if (cfq_rq_close(cfqd, cfqq, rq)) 3675 return true; 3676 3677 return false; 3678} 3679 3680/* 3681 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3682 * let it have half of its nominal slice. 3683 */ 3684static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3685{ 3686 enum wl_type_t old_type = cfqq_type(cfqd->active_queue); 3687 3688 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3689 cfq_slice_expired(cfqd, 1); 3690 3691 /* 3692 * workload type is changed, don't save slice, otherwise preempt 3693 * doesn't happen 3694 */ 3695 if (old_type != cfqq_type(cfqq)) 3696 cfqq->cfqg->saved_wl_slice = 0; 3697 3698 /* 3699 * Put the new queue at the front of the of the current list, 3700 * so we know that it will be selected next. 3701 */ 3702 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3703 3704 cfq_service_tree_add(cfqd, cfqq, 1); 3705 3706 cfqq->slice_end = 0; 3707 cfq_mark_cfqq_slice_new(cfqq); 3708} 3709 3710/* 3711 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3712 * something we should do about it 3713 */ 3714static void 3715cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3716 struct request *rq) 3717{ 3718 struct cfq_io_cq *cic = RQ_CIC(rq); 3719 3720 cfqd->rq_queued++; 3721 if (rq->cmd_flags & REQ_PRIO) 3722 cfqq->prio_pending++; 3723 3724 cfq_update_io_thinktime(cfqd, cfqq, cic); 3725 cfq_update_io_seektime(cfqd, cfqq, rq); 3726 cfq_update_idle_window(cfqd, cfqq, cic); 3727 3728 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3729 3730 if (cfqq == cfqd->active_queue) { 3731 /* 3732 * Remember that we saw a request from this process, but 3733 * don't start queuing just yet. Otherwise we risk seeing lots 3734 * of tiny requests, because we disrupt the normal plugging 3735 * and merging. If the request is already larger than a single 3736 * page, let it rip immediately. For that case we assume that 3737 * merging is already done. Ditto for a busy system that 3738 * has other work pending, don't risk delaying until the 3739 * idle timer unplug to continue working. 3740 */ 3741 if (cfq_cfqq_wait_request(cfqq)) { 3742 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3743 cfqd->busy_queues > 1) { 3744 cfq_del_timer(cfqd, cfqq); 3745 cfq_clear_cfqq_wait_request(cfqq); 3746 __blk_run_queue(cfqd->queue); 3747 } else { 3748 cfqg_stats_update_idle_time(cfqq->cfqg); 3749 cfq_mark_cfqq_must_dispatch(cfqq); 3750 } 3751 } 3752 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3753 /* 3754 * not the active queue - expire current slice if it is 3755 * idle and has expired it's mean thinktime or this new queue 3756 * has some old slice time left and is of higher priority or 3757 * this new queue is RT and the current one is BE 3758 */ 3759 cfq_preempt_queue(cfqd, cfqq); 3760 __blk_run_queue(cfqd->queue); 3761 } 3762} 3763 3764static void cfq_insert_request(struct request_queue *q, struct request *rq) 3765{ 3766 struct cfq_data *cfqd = q->elevator->elevator_data; 3767 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3768 3769 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3770 cfq_init_prio_data(cfqq, RQ_CIC(rq)); 3771 3772 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3773 list_add_tail(&rq->queuelist, &cfqq->fifo); 3774 cfq_add_rq_rb(rq); 3775 cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group, 3776 rq->cmd_flags); 3777 cfq_rq_enqueued(cfqd, cfqq, rq); 3778} 3779 3780/* 3781 * Update hw_tag based on peak queue depth over 50 samples under 3782 * sufficient load. 3783 */ 3784static void cfq_update_hw_tag(struct cfq_data *cfqd) 3785{ 3786 struct cfq_queue *cfqq = cfqd->active_queue; 3787 3788 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3789 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3790 3791 if (cfqd->hw_tag == 1) 3792 return; 3793 3794 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3795 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3796 return; 3797 3798 /* 3799 * If active queue hasn't enough requests and can idle, cfq might not 3800 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3801 * case 3802 */ 3803 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3804 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3805 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3806 return; 3807 3808 if (cfqd->hw_tag_samples++ < 50) 3809 return; 3810 3811 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3812 cfqd->hw_tag = 1; 3813 else 3814 cfqd->hw_tag = 0; 3815} 3816 3817static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3818{ 3819 struct cfq_io_cq *cic = cfqd->active_cic; 3820 3821 /* If the queue already has requests, don't wait */ 3822 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3823 return false; 3824 3825 /* If there are other queues in the group, don't wait */ 3826 if (cfqq->cfqg->nr_cfqq > 1) 3827 return false; 3828 3829 /* the only queue in the group, but think time is big */ 3830 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) 3831 return false; 3832 3833 if (cfq_slice_used(cfqq)) 3834 return true; 3835 3836 /* if slice left is less than think time, wait busy */ 3837 if (cic && sample_valid(cic->ttime.ttime_samples) 3838 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) 3839 return true; 3840 3841 /* 3842 * If think times is less than a jiffy than ttime_mean=0 and above 3843 * will not be true. It might happen that slice has not expired yet 3844 * but will expire soon (4-5 ns) during select_queue(). To cover the 3845 * case where think time is less than a jiffy, mark the queue wait 3846 * busy if only 1 jiffy is left in the slice. 3847 */ 3848 if (cfqq->slice_end - jiffies == 1) 3849 return true; 3850 3851 return false; 3852} 3853 3854static void cfq_completed_request(struct request_queue *q, struct request *rq) 3855{ 3856 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3857 struct cfq_data *cfqd = cfqq->cfqd; 3858 const int sync = rq_is_sync(rq); 3859 unsigned long now; 3860 3861 now = jiffies; 3862 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3863 !!(rq->cmd_flags & REQ_NOIDLE)); 3864 3865 cfq_update_hw_tag(cfqd); 3866 3867 WARN_ON(!cfqd->rq_in_driver); 3868 WARN_ON(!cfqq->dispatched); 3869 cfqd->rq_in_driver--; 3870 cfqq->dispatched--; 3871 (RQ_CFQG(rq))->dispatched--; 3872 cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq), 3873 rq_io_start_time_ns(rq), rq->cmd_flags); 3874 3875 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3876 3877 if (sync) { 3878 struct cfq_rb_root *st; 3879 3880 RQ_CIC(rq)->ttime.last_end_request = now; 3881 3882 if (cfq_cfqq_on_rr(cfqq)) 3883 st = cfqq->service_tree; 3884 else 3885 st = st_for(cfqq->cfqg, cfqq_class(cfqq), 3886 cfqq_type(cfqq)); 3887 3888 st->ttime.last_end_request = now; 3889 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3890 cfqd->last_delayed_sync = now; 3891 } 3892 3893#ifdef CONFIG_CFQ_GROUP_IOSCHED 3894 cfqq->cfqg->ttime.last_end_request = now; 3895#endif 3896 3897 /* 3898 * If this is the active queue, check if it needs to be expired, 3899 * or if we want to idle in case it has no pending requests. 3900 */ 3901 if (cfqd->active_queue == cfqq) { 3902 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3903 3904 if (cfq_cfqq_slice_new(cfqq)) { 3905 cfq_set_prio_slice(cfqd, cfqq); 3906 cfq_clear_cfqq_slice_new(cfqq); 3907 } 3908 3909 /* 3910 * Should we wait for next request to come in before we expire 3911 * the queue. 3912 */ 3913 if (cfq_should_wait_busy(cfqd, cfqq)) { 3914 unsigned long extend_sl = cfqd->cfq_slice_idle; 3915 if (!cfqd->cfq_slice_idle) 3916 extend_sl = cfqd->cfq_group_idle; 3917 cfqq->slice_end = jiffies + extend_sl; 3918 cfq_mark_cfqq_wait_busy(cfqq); 3919 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3920 } 3921 3922 /* 3923 * Idling is not enabled on: 3924 * - expired queues 3925 * - idle-priority queues 3926 * - async queues 3927 * - queues with still some requests queued 3928 * - when there is a close cooperator 3929 */ 3930 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3931 cfq_slice_expired(cfqd, 1); 3932 else if (sync && cfqq_empty && 3933 !cfq_close_cooperator(cfqd, cfqq)) { 3934 cfq_arm_slice_timer(cfqd); 3935 } 3936 } 3937 3938 if (!cfqd->rq_in_driver) 3939 cfq_schedule_dispatch(cfqd); 3940} 3941 3942static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3943{ 3944 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3945 cfq_mark_cfqq_must_alloc_slice(cfqq); 3946 return ELV_MQUEUE_MUST; 3947 } 3948 3949 return ELV_MQUEUE_MAY; 3950} 3951 3952static int cfq_may_queue(struct request_queue *q, int rw) 3953{ 3954 struct cfq_data *cfqd = q->elevator->elevator_data; 3955 struct task_struct *tsk = current; 3956 struct cfq_io_cq *cic; 3957 struct cfq_queue *cfqq; 3958 3959 /* 3960 * don't force setup of a queue from here, as a call to may_queue 3961 * does not necessarily imply that a request actually will be queued. 3962 * so just lookup a possibly existing queue, or return 'may queue' 3963 * if that fails 3964 */ 3965 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3966 if (!cic) 3967 return ELV_MQUEUE_MAY; 3968 3969 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3970 if (cfqq) { 3971 cfq_init_prio_data(cfqq, cic); 3972 3973 return __cfq_may_queue(cfqq); 3974 } 3975 3976 return ELV_MQUEUE_MAY; 3977} 3978 3979/* 3980 * queue lock held here 3981 */ 3982static void cfq_put_request(struct request *rq) 3983{ 3984 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3985 3986 if (cfqq) { 3987 const int rw = rq_data_dir(rq); 3988 3989 BUG_ON(!cfqq->allocated[rw]); 3990 cfqq->allocated[rw]--; 3991 3992 /* Put down rq reference on cfqg */ 3993 cfqg_put(RQ_CFQG(rq)); 3994 rq->elv.priv[0] = NULL; 3995 rq->elv.priv[1] = NULL; 3996 3997 cfq_put_queue(cfqq); 3998 } 3999} 4000 4001static struct cfq_queue * 4002cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic, 4003 struct cfq_queue *cfqq) 4004{ 4005 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 4006 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 4007 cfq_mark_cfqq_coop(cfqq->new_cfqq); 4008 cfq_put_queue(cfqq); 4009 return cic_to_cfqq(cic, 1); 4010} 4011 4012/* 4013 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 4014 * was the last process referring to said cfqq. 4015 */ 4016static struct cfq_queue * 4017split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq) 4018{ 4019 if (cfqq_process_refs(cfqq) == 1) { 4020 cfqq->pid = current->pid; 4021 cfq_clear_cfqq_coop(cfqq); 4022 cfq_clear_cfqq_split_coop(cfqq); 4023 return cfqq; 4024 } 4025 4026 cic_set_cfqq(cic, NULL, 1); 4027 4028 cfq_put_cooperator(cfqq); 4029 4030 cfq_put_queue(cfqq); 4031 return NULL; 4032} 4033/* 4034 * Allocate cfq data structures associated with this request. 4035 */ 4036static int 4037cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, 4038 gfp_t gfp_mask) 4039{ 4040 struct cfq_data *cfqd = q->elevator->elevator_data; 4041 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq); 4042 const int rw = rq_data_dir(rq); 4043 const bool is_sync = rq_is_sync(rq); 4044 struct cfq_queue *cfqq; 4045 4046 might_sleep_if(gfp_mask & __GFP_WAIT); 4047 4048 spin_lock_irq(q->queue_lock); 4049 4050 check_ioprio_changed(cic, bio); 4051 check_blkcg_changed(cic, bio); 4052new_queue: 4053 cfqq = cic_to_cfqq(cic, is_sync); 4054 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 4055 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask); 4056 cic_set_cfqq(cic, cfqq, is_sync); 4057 } else { 4058 /* 4059 * If the queue was seeky for too long, break it apart. 4060 */ 4061 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 4062 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 4063 cfqq = split_cfqq(cic, cfqq); 4064 if (!cfqq) 4065 goto new_queue; 4066 } 4067 4068 /* 4069 * Check to see if this queue is scheduled to merge with 4070 * another, closely cooperating queue. The merging of 4071 * queues happens here as it must be done in process context. 4072 * The reference on new_cfqq was taken in merge_cfqqs. 4073 */ 4074 if (cfqq->new_cfqq) 4075 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 4076 } 4077 4078 cfqq->allocated[rw]++; 4079 4080 cfqq->ref++; 4081 cfqg_get(cfqq->cfqg); 4082 rq->elv.priv[0] = cfqq; 4083 rq->elv.priv[1] = cfqq->cfqg; 4084 spin_unlock_irq(q->queue_lock); 4085 return 0; 4086} 4087 4088static void cfq_kick_queue(struct work_struct *work) 4089{ 4090 struct cfq_data *cfqd = 4091 container_of(work, struct cfq_data, unplug_work); 4092 struct request_queue *q = cfqd->queue; 4093 4094 spin_lock_irq(q->queue_lock); 4095 __blk_run_queue(cfqd->queue); 4096 spin_unlock_irq(q->queue_lock); 4097} 4098 4099/* 4100 * Timer running if the active_queue is currently idling inside its time slice 4101 */ 4102static void cfq_idle_slice_timer(unsigned long data) 4103{ 4104 struct cfq_data *cfqd = (struct cfq_data *) data; 4105 struct cfq_queue *cfqq; 4106 unsigned long flags; 4107 int timed_out = 1; 4108 4109 cfq_log(cfqd, "idle timer fired"); 4110 4111 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 4112 4113 cfqq = cfqd->active_queue; 4114 if (cfqq) { 4115 timed_out = 0; 4116 4117 /* 4118 * We saw a request before the queue expired, let it through 4119 */ 4120 if (cfq_cfqq_must_dispatch(cfqq)) 4121 goto out_kick; 4122 4123 /* 4124 * expired 4125 */ 4126 if (cfq_slice_used(cfqq)) 4127 goto expire; 4128 4129 /* 4130 * only expire and reinvoke request handler, if there are 4131 * other queues with pending requests 4132 */ 4133 if (!cfqd->busy_queues) 4134 goto out_cont; 4135 4136 /* 4137 * not expired and it has a request pending, let it dispatch 4138 */ 4139 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 4140 goto out_kick; 4141 4142 /* 4143 * Queue depth flag is reset only when the idle didn't succeed 4144 */ 4145 cfq_clear_cfqq_deep(cfqq); 4146 } 4147expire: 4148 cfq_slice_expired(cfqd, timed_out); 4149out_kick: 4150 cfq_schedule_dispatch(cfqd); 4151out_cont: 4152 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 4153} 4154 4155static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 4156{ 4157 del_timer_sync(&cfqd->idle_slice_timer); 4158 cancel_work_sync(&cfqd->unplug_work); 4159} 4160 4161static void cfq_put_async_queues(struct cfq_data *cfqd) 4162{ 4163 int i; 4164 4165 for (i = 0; i < IOPRIO_BE_NR; i++) { 4166 if (cfqd->async_cfqq[0][i]) 4167 cfq_put_queue(cfqd->async_cfqq[0][i]); 4168 if (cfqd->async_cfqq[1][i]) 4169 cfq_put_queue(cfqd->async_cfqq[1][i]); 4170 } 4171 4172 if (cfqd->async_idle_cfqq) 4173 cfq_put_queue(cfqd->async_idle_cfqq); 4174} 4175 4176static void cfq_exit_queue(struct elevator_queue *e) 4177{ 4178 struct cfq_data *cfqd = e->elevator_data; 4179 struct request_queue *q = cfqd->queue; 4180 4181 cfq_shutdown_timer_wq(cfqd); 4182 4183 spin_lock_irq(q->queue_lock); 4184 4185 if (cfqd->active_queue) 4186 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 4187 4188 cfq_put_async_queues(cfqd); 4189 4190 spin_unlock_irq(q->queue_lock); 4191 4192 cfq_shutdown_timer_wq(cfqd); 4193 4194#ifdef CONFIG_CFQ_GROUP_IOSCHED 4195 blkcg_deactivate_policy(q, &blkcg_policy_cfq); 4196#else 4197 kfree(cfqd->root_group); 4198#endif 4199 kfree(cfqd); 4200} 4201 4202static int cfq_init_queue(struct request_queue *q) 4203{ 4204 struct cfq_data *cfqd; 4205 struct blkcg_gq *blkg __maybe_unused; 4206 int i, ret; 4207 4208 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 4209 if (!cfqd) 4210 return -ENOMEM; 4211 4212 cfqd->queue = q; 4213 q->elevator->elevator_data = cfqd; 4214 4215 /* Init root service tree */ 4216 cfqd->grp_service_tree = CFQ_RB_ROOT; 4217 4218 /* Init root group and prefer root group over other groups by default */ 4219#ifdef CONFIG_CFQ_GROUP_IOSCHED 4220 ret = blkcg_activate_policy(q, &blkcg_policy_cfq); 4221 if (ret) 4222 goto out_free; 4223 4224 cfqd->root_group = blkg_to_cfqg(q->root_blkg); 4225#else 4226 ret = -ENOMEM; 4227 cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group), 4228 GFP_KERNEL, cfqd->queue->node); 4229 if (!cfqd->root_group) 4230 goto out_free; 4231 4232 cfq_init_cfqg_base(cfqd->root_group); 4233#endif 4234 cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT; 4235 cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT; 4236 4237 /* 4238 * Not strictly needed (since RB_ROOT just clears the node and we 4239 * zeroed cfqd on alloc), but better be safe in case someone decides 4240 * to add magic to the rb code 4241 */ 4242 for (i = 0; i < CFQ_PRIO_LISTS; i++) 4243 cfqd->prio_trees[i] = RB_ROOT; 4244 4245 /* 4246 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 4247 * Grab a permanent reference to it, so that the normal code flow 4248 * will not attempt to free it. oom_cfqq is linked to root_group 4249 * but shouldn't hold a reference as it'll never be unlinked. Lose 4250 * the reference from linking right away. 4251 */ 4252 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 4253 cfqd->oom_cfqq.ref++; 4254 4255 spin_lock_irq(q->queue_lock); 4256 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group); 4257 cfqg_put(cfqd->root_group); 4258 spin_unlock_irq(q->queue_lock); 4259 4260 init_timer(&cfqd->idle_slice_timer); 4261 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4262 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4263 4264 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4265 4266 cfqd->cfq_quantum = cfq_quantum; 4267 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4268 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4269 cfqd->cfq_back_max = cfq_back_max; 4270 cfqd->cfq_back_penalty = cfq_back_penalty; 4271 cfqd->cfq_slice[0] = cfq_slice_async; 4272 cfqd->cfq_slice[1] = cfq_slice_sync; 4273 cfqd->cfq_target_latency = cfq_target_latency; 4274 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4275 cfqd->cfq_slice_idle = cfq_slice_idle; 4276 cfqd->cfq_group_idle = cfq_group_idle; 4277 cfqd->cfq_latency = 1; 4278 cfqd->hw_tag = -1; 4279 /* 4280 * we optimistically start assuming sync ops weren't delayed in last 4281 * second, in order to have larger depth for async operations. 4282 */ 4283 cfqd->last_delayed_sync = jiffies - HZ; 4284 return 0; 4285 4286out_free: 4287 kfree(cfqd); 4288 return ret; 4289} 4290 4291/* 4292 * sysfs parts below --> 4293 */ 4294static ssize_t 4295cfq_var_show(unsigned int var, char *page) 4296{ 4297 return sprintf(page, "%d\n", var); 4298} 4299 4300static ssize_t 4301cfq_var_store(unsigned int *var, const char *page, size_t count) 4302{ 4303 char *p = (char *) page; 4304 4305 *var = simple_strtoul(p, &p, 10); 4306 return count; 4307} 4308 4309#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4310static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4311{ \ 4312 struct cfq_data *cfqd = e->elevator_data; \ 4313 unsigned int __data = __VAR; \ 4314 if (__CONV) \ 4315 __data = jiffies_to_msecs(__data); \ 4316 return cfq_var_show(__data, (page)); \ 4317} 4318SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4319SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4320SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4321SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4322SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4323SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4324SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4325SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4326SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4327SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4328SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4329SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1); 4330#undef SHOW_FUNCTION 4331 4332#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4333static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4334{ \ 4335 struct cfq_data *cfqd = e->elevator_data; \ 4336 unsigned int __data; \ 4337 int ret = cfq_var_store(&__data, (page), count); \ 4338 if (__data < (MIN)) \ 4339 __data = (MIN); \ 4340 else if (__data > (MAX)) \ 4341 __data = (MAX); \ 4342 if (__CONV) \ 4343 *(__PTR) = msecs_to_jiffies(__data); \ 4344 else \ 4345 *(__PTR) = __data; \ 4346 return ret; \ 4347} 4348STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4349STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4350 UINT_MAX, 1); 4351STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4352 UINT_MAX, 1); 4353STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4354STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4355 UINT_MAX, 0); 4356STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4357STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4358STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4359STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4360STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4361 UINT_MAX, 0); 4362STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4363STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1); 4364#undef STORE_FUNCTION 4365 4366#define CFQ_ATTR(name) \ 4367 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4368 4369static struct elv_fs_entry cfq_attrs[] = { 4370 CFQ_ATTR(quantum), 4371 CFQ_ATTR(fifo_expire_sync), 4372 CFQ_ATTR(fifo_expire_async), 4373 CFQ_ATTR(back_seek_max), 4374 CFQ_ATTR(back_seek_penalty), 4375 CFQ_ATTR(slice_sync), 4376 CFQ_ATTR(slice_async), 4377 CFQ_ATTR(slice_async_rq), 4378 CFQ_ATTR(slice_idle), 4379 CFQ_ATTR(group_idle), 4380 CFQ_ATTR(low_latency), 4381 CFQ_ATTR(target_latency), 4382 __ATTR_NULL 4383}; 4384 4385static struct elevator_type iosched_cfq = { 4386 .ops = { 4387 .elevator_merge_fn = cfq_merge, 4388 .elevator_merged_fn = cfq_merged_request, 4389 .elevator_merge_req_fn = cfq_merged_requests, 4390 .elevator_allow_merge_fn = cfq_allow_merge, 4391 .elevator_bio_merged_fn = cfq_bio_merged, 4392 .elevator_dispatch_fn = cfq_dispatch_requests, 4393 .elevator_add_req_fn = cfq_insert_request, 4394 .elevator_activate_req_fn = cfq_activate_request, 4395 .elevator_deactivate_req_fn = cfq_deactivate_request, 4396 .elevator_completed_req_fn = cfq_completed_request, 4397 .elevator_former_req_fn = elv_rb_former_request, 4398 .elevator_latter_req_fn = elv_rb_latter_request, 4399 .elevator_init_icq_fn = cfq_init_icq, 4400 .elevator_exit_icq_fn = cfq_exit_icq, 4401 .elevator_set_req_fn = cfq_set_request, 4402 .elevator_put_req_fn = cfq_put_request, 4403 .elevator_may_queue_fn = cfq_may_queue, 4404 .elevator_init_fn = cfq_init_queue, 4405 .elevator_exit_fn = cfq_exit_queue, 4406 }, 4407 .icq_size = sizeof(struct cfq_io_cq), 4408 .icq_align = __alignof__(struct cfq_io_cq), 4409 .elevator_attrs = cfq_attrs, 4410 .elevator_name = "cfq", 4411 .elevator_owner = THIS_MODULE, 4412}; 4413 4414#ifdef CONFIG_CFQ_GROUP_IOSCHED 4415static struct blkcg_policy blkcg_policy_cfq = { 4416 .pd_size = sizeof(struct cfq_group), 4417 .cftypes = cfq_blkcg_files, 4418 4419 .pd_init_fn = cfq_pd_init, 4420 .pd_reset_stats_fn = cfq_pd_reset_stats, 4421}; 4422#endif 4423 4424static int __init cfq_init(void) 4425{ 4426 int ret; 4427 4428 /* 4429 * could be 0 on HZ < 1000 setups 4430 */ 4431 if (!cfq_slice_async) 4432 cfq_slice_async = 1; 4433 if (!cfq_slice_idle) 4434 cfq_slice_idle = 1; 4435 4436#ifdef CONFIG_CFQ_GROUP_IOSCHED 4437 if (!cfq_group_idle) 4438 cfq_group_idle = 1; 4439 4440 ret = blkcg_policy_register(&blkcg_policy_cfq); 4441 if (ret) 4442 return ret; 4443#else 4444 cfq_group_idle = 0; 4445#endif 4446 4447 ret = -ENOMEM; 4448 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4449 if (!cfq_pool) 4450 goto err_pol_unreg; 4451 4452 ret = elv_register(&iosched_cfq); 4453 if (ret) 4454 goto err_free_pool; 4455 4456 return 0; 4457 4458err_free_pool: 4459 kmem_cache_destroy(cfq_pool); 4460err_pol_unreg: 4461#ifdef CONFIG_CFQ_GROUP_IOSCHED 4462 blkcg_policy_unregister(&blkcg_policy_cfq); 4463#endif 4464 return ret; 4465} 4466 4467static void __exit cfq_exit(void) 4468{ 4469#ifdef CONFIG_CFQ_GROUP_IOSCHED 4470 blkcg_policy_unregister(&blkcg_policy_cfq); 4471#endif 4472 elv_unregister(&iosched_cfq); 4473 kmem_cache_destroy(cfq_pool); 4474} 4475 4476module_init(cfq_init); 4477module_exit(cfq_exit); 4478 4479MODULE_AUTHOR("Jens Axboe"); 4480MODULE_LICENSE("GPL"); 4481MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4482